KR20240144160A - Laminated polyester film - Google Patents

Abstract

A laminated polyester film comprising a polyester film and a resin layer formed using a resin composition on at least one side of the polyester film, wherein the laminated polyester film satisfies all of the following requirements (1) to (3). (1) The resin layer has a roughened structure. (2) The resin composition contains the following compounds (A) and (B). (A) A low-polarity compound. (B) At least one compound selected from the group consisting of a binder resin and a crosslinking agent. (3) A roughness curve at a cut level of 80% of the surface of the resin layer has a load length ratio (Rmr(80)) of 76% or less as measured with a scanning probe microscope. A laminated polyester film which can form a fine roughened structure even in a thin film and has excellent handleability when winding the film into a roll shape, etc. can be provided.

Description

Laminated polyester film

The present invention relates to a laminated polyester film.

Polyester films, represented by polyethylene terephthalate films and polyethylene naphthalate films, have excellent mechanical properties, dimensional stability, flatness, heat resistance, chemical resistance, optical properties, etc., and are used for various purposes because they have excellent cost performance.

In addition, polyester films are suitably used for various purposes, such as release films for forming green sheets of laminated ceramic capacitors, base materials for interlayer insulating resin release, and base materials for dry film resist, by utilizing the smoothness of the film surface.

For the above-mentioned purposes, a polyester film for sheet forming with excellent surface smoothness is required to be wrinkle-free and have a good roll appearance when wound into a roll.

However, if the surface smoothness is increased, the slipperiness is reduced and air escape when winding or unwinding from a roll is poor, so winding misalignment or blocking occurs and handling is reduced.

In particular, with the recent increase in productivity, the trend toward thinner polyester films has been further progressing, and thus roll appearance quality at a higher level is required.

Therefore, in order to secure handleability, the non-smooth side (back side) is sometimes designed to be rougher than the smooth side due to particle mixing (e.g., patent document 1).

In addition, patent document 2 discloses a back resin layer having a surface in which a concave portion is formed by a sea-level structure as the back surface and an arithmetic mean roughness (Ra) of 10 to 80 nm.

However, patent documents 3 and 4 disclose a laminated film having a roughened layer by phase separation.

Japanese Patent Publication No. 2015-33811 Japanese Patent Publication No. 2013-60555 Japanese Patent Publication No. 2013-10323 Japanese Patent Publication No. 2021-24177

However, with the conventional particle-mixed film manufacturing method disclosed in Patent Document 1, it was difficult to control the formation of irregularities, and thus formation of a fine irregular structure was difficult.

In addition, in the films disclosed in patent documents 2 to 4, there was a problem that it was difficult to say that there was a fine uneven structure, or that the layer having the unevenness was thick.

More specifically, in cases where there was no fine roughness structure, wrinkles were likely to appear when winding into a roll, resulting in damage to the roll's appearance.

In addition, in cases where the layer having the unevenness is thick, there are cases where the flatness is damaged due to curling caused by curing shrinkage, and it is not suitable for thin film elongation of polyester film.

Accordingly, the present invention has been made in consideration of the above circumstances, and the problem to be solved is to provide a laminated polyester film which can form a fine rough structure even in a thin film and has excellent handling properties when winding the film into a roll shape, etc.

The inventors of the present invention, after careful examination, have found that the above problem can be solved by having the following configuration.

The present invention has the following aspects.

[1] A laminated polyester film comprising a polyester film and a resin layer formed by a resin composition on at least one side of the polyester film, wherein the laminated polyester film satisfies all of the requirements of (1) to (3) below.

(1) The above resin layer has a rough structure.

(2) The resin composition comprises the following compounds (A) and (B).

(A) Low polarity compound

(B) At least one selected from the group consisting of a binder resin and a crosslinking agent

(3) The load length ratio (Rmr(80)) of the roughness curve at the cutting level of 80% of the surface of the resin layer as measured by a scanning probe microscope is 76% or less.

[2] A laminated polyester film as described in [1], wherein the load length ratio (Rmr(50)) of the roughness curve at a cut level of 50% of the surface of the resin layer as measured by a scanning probe microscope is 60% or less.

[3] A laminated polyester film as described in [1] or [2], wherein the arithmetic mean roughness (Ra) of the surface of the resin layer is 20 nm or more as measured by a scanning probe microscope.

[4] A laminated polyester film according to any one of [1] to [3], wherein the ten-point average roughness (Rzjis) of the surface of the resin layer as measured by a scanning probe microscope is 70 nm or more.

[5] A laminated polyester film according to any one of [1] to [4] above, having an air leakage index of 130,000 seconds or less.

[6] A laminated polyester film according to any one of [1] to [5], wherein the low-polarity compound comprises at least one selected from the group consisting of wax and long-chain alkyl group-containing compounds.

[7] A laminated polyester film according to any one of [1] to [6], wherein the binder resin comprises at least one selected from the group consisting of (meth)acrylic resin, polyvinyl alcohol, and ion-conductive polymer compounds.

[8] A laminated polyester film according to any one of [1] to [7], wherein the crosslinking agent comprises at least one selected from the group consisting of a melamine compound and an oxazoline compound.

[9] A laminated polyester film according to any one of [1] to [8], wherein the resin composition comprises a crosslinking catalyst as compound (C).

[10] A laminated polyester film according to any one of [1] to [9], wherein the resin composition comprises fine particles as a compound (D).

[11] A laminated polyester film as described in any one of [1] to [10], used as a support for a ceramic green sheet in a manufacturing process of a laminated ceramic capacitor.

According to the present invention, a laminated polyester film is provided which can form a fine rough structure even in a thin film and has excellent handling properties when winding the film into a roll shape, etc.

In addition, since the laminated polyester film of the present invention has a fine uneven structure on the surface of the resin layer, when used for sheet molding, for example, there is an advantage in that even when a very smooth film is wound into a roll, it exhibits good windability and wrinkles are unlikely to occur.

In addition, since the laminated polyester film of the present invention can form a resin layer into a thin film, it can also respond to the thin film elongation of the polyester film, and can contribute to the improvement of productivity by reducing the frequency of product roll switching during processing.

Figure 1 is an image of the resin layer of Example 1-1 observed using a scanning probe microscope.

Next, an example of an embodiment of the present invention will be described. However, the present invention is not limited to the embodiment described below.

In this specification, when the expression "(meth)acryl" is used, "(meth)acryl" means one or both of "acrylic" and "methacrylic". In addition, similarly, "(meth)acrylic acid" means one or both of "acrylic acid" and "methacrylic acid", "(meth)acrylate" means one or both of "acrylate" and "methacrylate", and "(meth)acryloyl" means one or both of "acryloyl" and "methacryloyl". The same applies to other terms as above.

<<<Laminated polyester film>>>

The laminated polyester film of the present invention (hereinafter also referred to as “the laminated polyester film”) comprises a polyester film (hereinafter also referred to as “the polyester film”) and a resin layer formed by a resin composition on at least one side of the polyester film (hereinafter also referred to as “the resin layer”).

As for the laminated configuration of the present laminated polyester film, it may be a configuration in which a resin layer is formed on one side of the polyester film and the other side has the surface of the polyester film as it is, or it may be a configuration in which another layer is formed on the other side.

Additionally, it may be a configuration formed by forming a resin layer on both sides of a polyester film.

Additionally, the resin layer may be formed directly on the polyester film, but another layer may be provided between the polyester film and the resin layer.

<<Polyester film>>

This polyester film serves as a substrate of this laminated polyester film. This polyester film may have a single-layer structure or a multilayer structure. When this polyester film has a multilayer structure, this polyester film may have a two-layer structure, a three-layer structure, etc., and as long as it does not deviate from the gist of the present invention, it may have four or more multilayers, and the number of layers is not particularly limited.

In addition, when the polyester film has a multilayer structure of two or more layers, 2-layer and 3-layer, or 3-layer and 3-layer, is particularly preferable. When the polyester film has a multilayer structure, it is also preferable to have a structure in which surface layers are provided on both sides of the middle layer.

In particular, when utilizing the smoothness of the present laminated polyester film, it is preferable that at least one side of the present polyester film is a side having excellent smoothness. As a method of such design, for example, a method may be given in which the present polyester film is designed to have excellent smoothness on both sides as a single-layer, two-type three-layer, or three-type three-layer structure, or a method in which the present polyester film is designed to have excellent smoothness on one side as a three-type three-layer structure, and the other side as having a different roughness.

In addition, the polyester film may be a non-stretched film (sheet) or a stretched film. Among these, a stretched film stretched in one or two directions is preferable. Among these, a biaxially stretched film is more preferable in terms of excellent balance of mechanical properties and flatness.

<Polyester>

The polyester, which is the raw material of this polyester film, refers to a polymer compound having a continuous ester bond in the main chain, and may be a homopolyester or a copolymer polyester. Specifically, a polyester obtained by polycondensation reaction of a dicarboxylic acid component and a diol component can be mentioned. In addition, when the dicarboxylic acid component is 100 mol%, it is preferable to use a polyester containing more than 50 mol% of an aromatic dicarboxylic acid or an aliphatic dicarboxylic acid.

As the above dicarboxylic acid component, examples thereof include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, 4,4'-diphenyletherdicarboxylic acid, and 4,4'-diphenylsulfonedicarboxylic acid, and aliphatic dicarboxylic acids such as adipic acid, suberic acid, sebacic acid, dimer acid, dodecanedioic acid, cyclohexanedicarboxylic acid, and ester derivatives thereof.

Examples of the above diol component include ethylene glycol, 1,2-propanediol, 1,3-propanediol, neopentyl glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-hexanedimethanol, diethylene glycol, triethylene glycol, polyalkylene glycol, 2,2-bis(4-hydroxyethoxyphenyl)propane, isosorbate, and spiroglycol.

When the above polyester is a homopolyester, it is preferably obtained by condensation of an aromatic dicarboxylic acid and an aliphatic diol. As the aromatic dicarboxylic acid, preferably terephthalic acid, 2,6-naphthalenedicarboxylic acid, etc. can be mentioned, and as the aliphatic diol, preferably ethylene glycol, diethylene glycol, 1,4-cyclohexanedimethanol, etc. can be mentioned. Representative homopolyesters include polyethylene terephthalate (PET), polyethylene-2,6-naphthalenedicarboxylate (PEN), etc., and polyethylene terephthalate is preferable.

Meanwhile, the copolyester is preferably a polycondensation polymer of a dicarboxylic acid component and an aliphatic diol, for example. As the dicarboxylic acid component, preferably one or more kinds of isophthalic acid, phthalic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, adipic acid, sebacic acid, and oxycarboxylic acid (for example, p-oxybenzoic acid, etc.) can be mentioned. In addition, as the aliphatic diol, preferably one or more kinds of ethylene glycol, diethylene glycol, propylene glycol, butanediol, 1,4-cyclohexanedimethanol, and neopentyl glycol can be mentioned. It is more preferable that the copolyester contains terephthalic acid as the dicarboxylic acid component and ethylene glycol as the aliphatic diol.

In the case where the above polyester is a copolymer polyester, it is preferable that it is a copolymer containing 30 mol% or less of a third component. The third component is a component other than a compound that is a main component (i.e., a component with the largest content) of the dicarboxylic acid component constituting the polyester and a compound that is a main component of the diol component, and for example, in copolymerized polyethylene terephthalate, it is a component other than terephthalic acid and ethylene glycol.

In addition, the copolyester may contain a structural unit derived from a difunctional compound other than a dicarboxylic acid component and an aliphatic diol. The structural unit derived from a difunctional compound other than a dicarboxylic acid component and an aliphatic diol is preferably 20 mol% or less, more preferably 10 mol% or less, based on the total moles of all structural units constituting the polyester. Examples of the difunctional compound include various hydroxycarboxylic acids, aromatic diols, and the like.

The content of terephthalic acid among the total dicarboxylic acid components constituting the present polyester film is preferably 50 mol% or more, more preferably 70 mol% or more, and even more preferably 90 mol% or more.

In addition, the ethylene glycol content among the total diol components constituting the present polyester film is preferably 50 mol% or more, more preferably 70 mol% or more, and even more preferably 90 mol% or more.

Additionally, the upper limit of the content of terephthalic acid and ethylene glycol is 100 mol%.

Additionally, the polyester may be a recycled polyester or a polyester derived from biomass.

<Polycondensation catalyst>

There is no particular limitation as to the polycondensation catalyst used when polycondensing the above polyester, and any conventionally known compound can be used, and examples thereof include titanium compounds, germanium compounds, antimony compounds, manganese compounds, aluminum compounds, magnesium compounds, and calcium compounds.

Among these, at least one of a titanium compound and an antimony compound is preferable, and in particular, it is preferable to use a polyester obtained by using a titanium compound.

Therefore, it is preferable that the present polyester film contains at least one of a titanium compound and an antimony compound, and it is more preferable that it contains a titanium compound.

By using the above titanium compound, the amount of antimony compound used can be reduced as a result, so the risk of new protrusion formation due to precipitation of the antimony compound on the film surface is reduced, and a high degree of surface smoothness can be maintained.

Therefore, as a particularly preferable form, when the polyester film has a multilayer structure, it can be mentioned that the polyester constituting at least one surface layer uses a titanium compound.

The content of titanium element derived from the titanium compound in the surface layer is preferably 3 ppm or more and 40 ppm or less, and more preferably 4 ppm or more and 35 ppm or less, on a mass basis. In addition, when the surface layer contains at least one of an antimony compound and a titanium compound, the content of antimony element in the surface layer is preferably 0 ppm or more and 100 ppm or less. Within this range, foreign substances caused by the catalyst can be reduced without lowering the manufacturing efficiency.

In addition, from the viewpoint of productivity and cost, it is also desirable that the polyester constituting the layers other than the surface layer not use titanium compounds.

From the above, since the polyester film contains a titanium compound, it can be made into a polyester film having excellent smoothness. Then, when it is made into a laminated polyester film having the resin layer, the laminated polyester film can be suitably used for sheet forming, etc.

<Intrinsic viscosity>

The intrinsic viscosity (IV) of the polyester constituting the present polyester film is preferably 0.50 dL/g or more, more preferably 0.55 dL/g or more, and even more preferably 0.60 dL/g or more. Within this range, there is an advantage such as increased shear stress during mixing, thereby highly dispersing the particles. In addition, the intrinsic viscosity (IV) of the polyester is, for example, 1.00 dL/g or less.

In addition, the “intrinsic viscosity (IV) of the polyester constituting the polyester film” refers to the intrinsic viscosity (IV) of the mixed polyester when two or more types of polyester having different intrinsic viscosities (IV) are used.

When the polyester film has a multilayer structure, it is preferable that the intrinsic viscosity (IV) of the polyester constituting the surface layer is within the above range.

<Particle>

It is also possible to include particles in this polyester film. By including particles in the polyester film, the film is provided with lubricity, prevents the occurrence of flaws in each process, and improves handling properties.

The type of particles contained in the present polyester film is not particularly limited as long as they are particles capable of imparting activity, and specific examples thereof include inorganic particles such as silica, calcium carbonate, magnesium carbonate, barium carbonate, calcium sulfate, calcium phosphate, magnesium phosphate, kaolin, aluminum oxide, and titanium oxide, as well as crosslinked polymers such as crosslinked silicone resin particles, crosslinked acrylic resin particles, crosslinked styrene-acrylic resin particles, and crosslinked polyester particles, and organic particles such as calcium oxalate and ion exchange resin. Among these, organic particles, silica, and aluminum oxide are preferable. Among these, from the viewpoint of hardening the layer, preventing scratches on the film surface, and maintaining smoothness, it is preferable to contain aluminum oxide.

In addition, during the polyester manufacturing process, precipitated particles in which a portion of a metal compound such as a catalyst is precipitated and finely dispersed may be used.

There is no particular limitation on the shape of the particles used, and any shape such as spherical, blocky, rod-shaped, or flat may be used.

In addition, there are no special restrictions on the hardness, specific gravity, color, etc. These series of particles may be used in combination of two or more types as needed.

In addition, the average particle size of the particles used is usually 5 ㎛ or less, preferably 0.01 to 3 ㎛, more preferably 0.02 to 1 ㎛, and even more preferably 0.03 to 0.5 ㎛. When it is 5 ㎛ or less, the surface roughness of the film does not become too rough, and problems do not occur in cases such as forming a resin layer and various surface functional layers other than the resin layer in a post-process, which is preferable. In addition, when the average particle size is in this range, the haze is suppressed low, and it is easy to secure transparency as the entire laminated polyester film.

In addition, the average particle diameter can be obtained by measuring the diameters of 10 or more particles by observing them with a scanning electron microscope (SEM) and taking the average value. In that case, in the case of non-spherical particles, the average value of the longest diameter and the shortest diameter can be measured as the diameter of each particle.

When containing particles in this polyester film, it is preferable to provide a surface layer and an intermediate layer, for example, and contain particles in the surface layer. Also, when the design is such that the front and back are different by a three-layer structure or the like, it is also possible to contain particles in at least one surface layer.

The particle content, although it depends on the average particle diameter, is usually 5000 ppm or less, preferably 3000 ppm or less, and more preferably 1000 ppm or less, in terms of mass, in the layer containing particles. When no particles are contained or the particle content is small, sufficient slipperiness cannot be imparted, and although the transparency of the polyester film is increased, the slipperiness may be insufficient. Therefore, research is necessary to improve the slipperiness, such as by laminating the resin layer described later. In addition, when it is 5000 ppm or less, the transparency of the polyester film can be sufficiently secured. In addition, in the layer containing particles, the particle content is not particularly limited, and is, for example, 50 ppm or more, preferably 100 ppm or more.

The resin layer described later may be provided on a layer of a polyester film containing particles, or may be provided on a layer that does not substantially contain particles. In addition, the surface (opposite surface) opposite to the surface on which the resin layer is provided in the polyester film may be a layer that does not substantially contain particles, or may be a layer that does contain particles. In the present invention, even if both the surface on which the resin layer is provided and the opposite surface are layers that do not substantially contain particles, the windability, etc. can be improved by the resin layer having the uneven structure described later. In addition, by making one or both of the surface on which the resin layer is provided and the opposite surface a layer containing particles, the windability can be easily improved even further.

When providing excellent smoothness to at least one surface of the polyester film, the surface layer on the smooth surface side may contain particles, or may substantially not contain particles; however, when making a very highly smooth film, it is preferable that it contains substantially no particles.

In addition, "substantially does not contain" means not containing intentionally, and specifically, it refers to a particle content (particle concentration) of less than 50 ppm by mass, more preferably 40 ppm or less, and even more preferably 30 ppm or less.

In this case, by laminating the resin layer on the surface layer of the smooth surface side and/or on the surface layer on the opposite side of the smooth surface side, the handling property when the film is wound into a roll shape can be improved. Among these, from the viewpoint of improving the handling property while maintaining the smoothness of the film, it is preferable to make at least one side smooth and to laminate the resin layer on the opposite side.

There is no particular limitation on the method for adding particles to the polyester film, and any conventionally known method can be adopted. For example, in the case of a multilayer polyester film, the particles can be added at any stage of manufacturing the polyester constituting each layer, but it is preferable to add the particles after the esterification or ester exchange reaction is completed.

<Other>

In order to suppress the amount of precipitation of oligomer components, a film may be manufactured using polyester with a low content of oligomer components as a raw material. Various known methods can be used as a method for manufacturing polyester with a low content of oligomer components, and examples thereof include a method of solid-phase polymerization after polyester manufacturing.

In addition, by forming the polyester film into a composition of three or more layers and forming the surface layer of the polyester film into a layer using a polyester raw material having a low content of oligomer components, the amount of precipitation of oligomer components can be suppressed.

In addition, polyester can be obtained by esterification or ester exchange reaction, and then by melt polycondensation under reduced pressure at a high reaction temperature.

In addition, in addition to the particles described above, conventionally known ultraviolet absorbers, antioxidants, antistatic agents, heat stabilizers, lubricants, dyes, pigments, etc. may be added to the polyester film as needed.

The thickness of the polyester film is not particularly limited as long as it is within a range that can be formed into a film, but from the viewpoints of mechanical strength, handleability, and productivity, it is preferably 1 µm or more, more preferably 10 µm or more, even more preferably 19 µm or more, and particularly preferably 25 µm or more, and preferably 200 µm or less, more preferably 125 µm or less, even more preferably 80 µm or less, and particularly preferably 50 µm or less.

<Method for manufacturing polyester film>

Next, a specific description will be given of manufacturing examples of the polyester film, but the present invention is not limited at all to the following manufacturing examples. For example, when manufacturing a biaxially oriented film, a method is preferably used in which the dried pellets of the polyester raw material described above are extruded as a molten sheet from a die using a melting extrusion device such as an extruder, and then cooled and solidified by a cooling roll such as a rotary cooling drum to obtain an unstretched sheet. In this case, in order to improve the flatness of the sheet, it is preferable to increase the adhesion between the sheet and the cooling roll, and an electrostatically applied adhesion method and/or a liquid application adhesion method are preferably employed.

The unstretched sheet obtained next is stretched in two directions. In this case, the unstretched sheet is first stretched in one direction by a roller or tenter type stretching machine. The stretching temperature is usually 70 to 120°C, preferably 80 to 110°C, and the stretching ratio is usually 2.5 to 7.0 times, preferably 3.0 to 6.0 times.

Next, stretching is performed in a direction orthogonal to the stretching direction of the first stage. In this case, the stretching temperature is usually 70 to 170°C, and the stretching ratio is usually 3.0 to 7.0 times, preferably 3.5 to 6.0 times.

And, continuously, heat treatment is performed at a temperature of usually 180 to 270℃, under tension or under relaxation of 30% or less, to obtain a biaxially stretched film. This heat treatment is also called a heat setting process. The heat treatment may be performed in two or more stages at different temperatures.

In addition, cooling may be performed in a cooling zone after heat treatment. The cooling temperature is preferably higher than the glass transition temperature (Tg) of the polyester constituting the film, and more specifically, it is preferably in the range of 100 to 160°C. This cooling may be performed in two or more stages at different temperatures.

In the above stretching, a method of performing unidirectional stretching in two or more stages may be adopted. In that case, it is preferable that the stretching ratios in the two directions are each within the above range.

In addition, a simultaneous biaxial stretching method can also be employed in the production of the present polyester film. The simultaneous biaxial stretching method is a method of simultaneously stretching and orienting the above-mentioned unstretched sheet in the machine direction (longitudinal direction) and the width direction (horizontal direction) under temperature control at usually 70 to 120°C, preferably 80 to 110°C, and the stretching ratio is preferably 4 to 50 times, more preferably 7 to 35 times, and even more preferably 10 to 25 times, in terms of area magnification.

And, successively, heat treatment is performed at a temperature of usually 170 to 250℃ under tension or under relaxation of 30% or less to obtain a stretched oriented film. With regard to a simultaneous two-axis stretching device employing the above-described stretching method, a conventionally known stretching method such as a screw method, a pantograph method, and a linear drive method can be employed.

<<Resin layer>>

The present laminated polyester film has a resin layer formed from a resin composition on at least one side of the polyester film. The resin layer may be a cured resin layer.

As described above, the present resin layer is formed of a resin composition (hereinafter also referred to as “present composition”) and has a rough structure.

<Uneven Structure>

The uneven structure of this resin layer is a fine shape formed by phase separation. The uneven structure due to phase separation is that the composition containing resins with different compatibility causes phase separation during processes such as application, stretching, drying, curing, and heat treatment, thereby forming an uneven structure on the surface. More specifically, the uneven structure is formed on the surface by forming concave or convex portions by phase separation.

Additionally, the structure can be confirmed by various surface analysis methods, such as atomic force microscopy (scanning probe microscopy).

Here, in the present invention, “resin” refers to a main component involved in film formation. More specifically, “resin” includes compounds (A) and (B) described below.

<Resin composition>

The present composition comprises the following compounds (A) and (B).

(A) Low polarity compound

(B) At least one selected from the group consisting of a binder resin and a crosslinking agent.

The total content of compounds (A) and (B) included in the present composition is preferably 50 mass% or more as a nonvolatile component. More preferably, it is 60 mass% or more, and even more preferably, it is 65 mass% or more. When the total content is in this range, the effect of phase separation is sufficiently exerted, and it becomes easy to obtain the desired fine uneven structure. In addition, the total content of compounds (A) and (B) is not particularly limited with respect to the upper limit, and may be 100 mass% or less.

(((Compound (A))))

The present composition contains (A) a low-polarity compound (compound (A)). As the low-polarity compound (A), there is no particular limitation, and a conventionally known compound can be used, and specifically, a conventionally known compound can be used as a release agent. As the compound (A), examples thereof include wax, a long-chain alkyl group-containing compound, a fluorine compound, a silicone compound, and the like. Among these, at least one of a wax and a long-chain alkyl group-containing compound is preferable, and a wax is more preferable. In the present composition, the compound (A) may be used alone, or two or more may be used in combination.

As described above, the uneven structure of the present resin layer is formed by the phase separation of resins having different compatibility, but since the present composition contains the compound (A), the fine uneven structure can be effectively expressed by the water-repellent and/or oil-repellent effect of the low-polarity compound (A). The mechanism by which the unevenness is formed by the water-repellent and/or oil-repellent effect is not clear, but it is presumed that the fine unevenness is formed more effectively by repelling other resins by the water-repellent and/or oil-repellent effect, and forming convex portions by the repelled resin.

(wax)

Examples of the waxes include natural wax, synthetic wax, and modified wax.

Natural waxes include plant waxes, animal waxes, mineral waxes, and petroleum waxes.

Examples of plant-based waxes include candelilla wax, carnauba wax, rice wax, rose wax, and jojoba oil.

Animal waxes include beeswax, lanolin, and spermaceti.

Mineral waxes include montan wax, ozokerite, and ceresin.

Examples of petroleum waxes include paraffin wax, microcrystalline wax, and petrolatum.

Synthetic waxes include synthetic hydrocarbons, modified waxes, hydrogenated waxes, fatty acids, acid amides, amines, imides, ester waxes, and ketones.

Examples of synthetic waxes include Fischer-Tropsch wax (also known as Sasol wax) and polyethylene wax. In addition, examples thereof include the following polymers, which are low-molecular-weight polymers (specifically, polymers having a number-average molecular weight of 500 to 20,000), namely, polypropylene, ethylene-acrylic acid copolymers, polyethylene glycol, polypropylene glycol, and block or graft bonds of polyethylene glycol and polypropylene glycol.

As modified waxes, examples thereof include montan wax derivatives, paraffin wax derivatives, and microcrystalline wax derivatives. The derivatives herein are compounds obtained by any of refining, oxidation, esterification, and saponification treatments, or a combination thereof. As hydrogenated waxes, examples thereof include hydrogenated castor oil and hydrogenated castor oil derivatives.

Among these, from the viewpoint of having excellent performance in forming irregularities by phase separation, a synthetic wax is preferable as the (A) low-polarity compound, and among these, a polyethylene wax is more preferable, and an oxidized polyethylene wax is even more preferable.

In addition, when the composition is diluted with a solvent such as water to make a coating solution, the wax may be dispersed with a surfactant or the like to make a wax emulsion and then mixed into the coating solution.

The number average molecular weight of the synthetic wax is usually in the range of 500 to 30,000, preferably 1,000 to 15,000, and more preferably 2,000 to 8,000, from the viewpoints of roughness formation performance by phase separation and handleability. In addition, the number average molecular weight is a value converted to polystyrene as measured using gel permeation chromatography (GPC).

In addition, when forming the resin layer, considering heating for crosslinking, etc., among the waxes, the melting point or softening point is preferably 80°C or higher, more preferably 110°C or higher. On the other hand, from the viewpoint of controlling phase separation performance after heat treatment, the temperature is preferably 200°C or lower, more preferably 170°C or lower, and even more preferably 150°C or lower. In particular, when the heat treatment process is a trigger for phase separation, although it is not clear, it is presumed that the wax melts and the melted wax repels other resins, thereby forming a convex portion.

Additionally, the melting point of wax can be measured by differential scanning calorimetry (DSC).

(Long-chain alkyl group-containing compound)

A long-chain alkyl group-containing compound is a compound having a straight-chain or branched alkyl group having 6 or more carbon atoms, preferably 8 or more, more preferably 12 or more.

As the alkyl group, examples thereof include alkyl groups having 6 to 30 carbon atoms, such as a hexyl group, an octyl group, a decyl group, a lauryl group, an octadecyl group, and a behenyl group. Examples of the compound having an alkyl group include various long-chain alkyl group-containing polymer compounds, long-chain alkyl group-containing amine compounds, long-chain alkyl group-containing ether compounds, and long-chain alkyl group-containing quaternary ammonium salts. Considering heat resistance, a polymer compound is preferable, and from the viewpoint that a roughening performance by an appropriate phase separation can be effectively obtained at a small content, a polymer compound having a long-chain alkyl group in a side chain is more preferable.

A polymer compound having a long-chain alkyl group in the side chain can be obtained by reacting a polymer having a reactive group with a compound having an alkyl group capable of reacting with the reactive group. Examples of the reactive group include a hydroxyl group, an amino group, a carboxyl group, an acid anhydride, and the like. Examples of the compound having these reactive groups include polyvinyl alcohol, polyethyleneimine, polyethyleneamine, a polyester resin containing a reactive group, a poly(meth)acrylic resin containing a reactive group, and the like. Among these, polyvinyl alcohol is preferable in consideration of ease of handling. The degree of polymerization of the polyvinyl alcohol used is not particularly limited, but is usually 100 or more, preferably 300 to 40,000. In addition, the degree of saponification of polyvinyl alcohol is not particularly limited, but is usually 70 mol% or more, preferably 70 to 99.9 mol%, more preferably 80 to 97 mol%, and even more preferably 86 to 95 mol%.

Examples of the compound having an alkyl group capable of reacting with the above reactive group include long-chain alkyl group-containing isocyanates such as hexyl isocyanate, octyl isocyanate, decyl isocyanate, lauryl isocyanate, octadecyl isocyanate, and behenyl isocyanate; long-chain alkyl group-containing acid chlorides such as hexanoyl chloride, octanoyl chloride, decanoyl chloride, lauroyl chloride, octadecanoyl chloride, and behenoyl chloride; long-chain alkyl group-containing amines; and long-chain alkyl group-containing alcohols. Among these, considering ease of handling, long-chain alkyl group-containing isocyanates are preferable, and octadecyl isocyanate is particularly preferable.

In addition, a polymer compound having a long-chain alkyl group in the side chain can also be obtained by polymerization of a long-chain alkyl (meth)acrylate or copolymerization of a long-chain alkyl (meth)acrylate with another vinyl group-containing monomer. Examples of the long-chain alkyl (meth)acrylate include hexyl (meth)acrylate, octyl (meth)acrylate, decyl (meth)acrylate, lauryl (meth)acrylate, octadecyl (meth)acrylate, and behenyl (meth)acrylate.

(Fluorine compounds)

As the fluorine compound, it is a compound containing a fluorine atom in the compound. From the viewpoint of the appearance of the coating by inline coating, an organic fluorine compound is suitably used, and examples thereof include a perfluoroalkyl group-containing compound, a polymer of an olefin compound containing a fluorine atom, an aromatic fluorine compound such as fluorobenzene, etc. From the viewpoint that the performance of forming irregularities by an appropriate phase separation can be effectively obtained with a small content, a compound having a perfluoroalkyl group is preferable. In addition, as the fluorine compound, a compound containing a long-chain alkyl compound as described above can also be used.

Examples of the compound having a perfluoroalkyl group include perfluoroalkyl (meth)acrylate, perfluoroalkyl methyl (meth)acrylate, 2-perfluoroalkyl ethyl (meth)acrylate, 3-perfluoroalkyl propyl (meth)acrylate, 3-perfluoroalkyl-1-methylpropyl (meth)acrylate, 3-perfluoroalkyl-2-propenyl (meth)acrylate, and other perfluoroalkyl group-containing (meth)acrylates or polymers thereof; perfluoroalkyl methyl vinyl ether, 2-perfluoroalkyl ethyl vinyl ether, 3-perfluoropropyl vinyl ether, 3-perfluoroalkyl-1-methylpropyl vinyl ether, 3-perfluoroalkyl-2-propenyl vinyl ether, and other perfluoroalkyl group-containing vinyl ethers or polymers thereof. Considering heat resistance, a polymer is preferable. The polymer may be a single compound or a polymer of multiple compounds. In addition, from the viewpoint that the performance of forming irregularities by an appropriate phase separation can be effectively obtained with a small content, the perfluoroalkyl group is preferably one having 3 to 11 carbon atoms. In addition, a polymer with a compound containing a long-chain alkyl compound as described above may be used, and from the viewpoint of adhesion to a polyester film as a base material, a polymer with vinyl chloride is also preferably used.

(silicon compound)

A silicone compound is a compound having a silicone structure within the molecule, and examples thereof include silicone emulsion, acrylic graft silicone, silicone graft acrylic, amino-modified silicone, perfluoroalkyl-modified silicone, and alkyl-modified silicone. Considering heat resistance, it is preferable to contain a curable silicone resin.

As for the type of curable silicone resin, it can be used in any type of curing reaction, such as addition type, condensation type, ultraviolet curing type, or electron beam curing type.

The content of compound (A) in the present composition is, as a proportion of the total nonvolatile components in the present composition, preferably in a range of 5 to 90 mass%, more preferably 10 to 80 mass%, and even more preferably 20 to 60 mass%. By setting the content to 5 mass% or more, the uneven structure by phase separation can be sufficiently formed. Furthermore, by setting the content to 90 mass% or less, the content of other resins can be secured, and the unevenness formation performance by phase separation can be appropriately adjusted.

(((Compound (B))))

The present composition contains, as compound (B), at least one selected from a binder resin and a crosslinking agent.

The above compound (B) can also contribute to the formation of a fine rough structure by phase separation, and can also improve the applicability when the composition is used as a coating solution.

((Binder Resin))

The binder resin selected as the compound (B) is defined as a polymer compound having a number average molecular weight (Mn) of 1000 or more as measured by gel permeation chromatography (GPC) in accordance with the “Polymer Compound Safety Evaluation Flow Scheme” (hosted by the Chemical Substances Council, November 1985), and having a film-forming property.

As such (B) binder resin, there is no particular limitation, and a conventionally known binder resin can be used. For example, (meth)acrylic resin, polyvinyl alcohol, polyester resin, ion-conductive polymer compound, polyurethane resin, etc. can be mentioned. Among these, from the viewpoints of high hydrophilicity, maintenance of roughening formation performance by phase separation, and film formation, it is preferable to use at least one of (meth)acrylic resin, polyvinyl alcohol, and ion-conductive polymer compound, and it is more preferable to use at least one of (meth)acrylic resin and polyvinyl alcohol. In the present composition, the binder resin may be used alone, or two or more types may be used in combination.

((meth)acrylic resin)

(Meth)Acrylic resin is a polymer containing a polymerizable monomer including an acrylic or methacrylic monomer. These may be a homopolymer, a copolymer, or a copolymer with a polymerizable monomer other than an acrylic or methacrylic monomer.

The (meth)acrylic polymer is a polymer having a structural unit derived from (meth)acrylic acid or (meth)acrylic acid alkyl esters. The (meth)acrylic polymer may be at least one polymer selected from (meth)acrylic acid and (meth)acrylic acid alkyl esters, or may be a copolymer of at least one selected from these and at least one selected from monomers other than these, for example, styrene or a styrene derivative, a monomer containing a hydroxyl group, etc.

In addition, copolymers of these polymers with other polymers (e.g., polyester, polyurethane, etc.) are also included. For example, block copolymers, graft copolymers. That is, the (meth)acrylic resin may be a (meth)acrylic-modified polyester resin or a (meth)acrylic-modified polyurethane resin.

Alternatively, a polymer (or in some cases a mixture of polymers) obtained by polymerizing a polymerizable monomer in a polyester solution or a polyester dispersion is also included. Similarly, a polymer (or in some cases a mixture of polymers) obtained by polymerizing a polymerizable monomer in a polyurethane solution or a polyurethane dispersion is also included. Likewise, a polymer (or in some cases a mixture of polymers) obtained by polymerizing a polymerizable monomer in another polymer solution or dispersion is also included, and these are also referred to herein as a (meth)acrylic modified polyester resin or a (meth)acrylic modified polyurethane resin. In addition, the polyester or polyurethane used in the (meth)acrylic resin can be appropriately selected and used from those exemplified as the polyester or polyurethane used in the binder resin described below.

In addition, (meth)acrylic resin may contain a hydroxyl group or amino group to further improve adhesion to polyester film.

As the above polymerizable monomer, there is no particular limitation, but particularly representative compounds include, for example, various carboxyl group-containing monomers and salts thereof, such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid, fumaric acid, maleic acid, and citraconic acid; various hydroxyl group-containing monomers, such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, monobutyl hydroxy fumarate, and monobutyl hydroxy itaconate; various alkyl (meth)acrylic acid esters, such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, and lauryl (meth)acrylate; Examples thereof include various nitrogen-containing monomers such as (meth)acrylamide, diacetone acrylamide, or (meth)acrylonitrile; nitrogen-containing monomers containing a hydroxyl group such as N-methylol(meth)acrylamide; various styrene derivatives such as styrene, α-methylstyrene, divinylbenzene, and vinyltoluene; various vinyl esters such as vinyl propionate; various silicon-containing polymerizable monomers such as γ-methacryloxypropyltrimethoxysilane and vinyltrimethoxysilane; phosphorus-containing vinyl monomers; various halogenated vinyls such as vinyl chloride and vinylidene chloride; and various conjugated dienes such as butadiene.

Among the above (meth)acrylic resins, a polymer formed by polymerizing a polymerizable monomer including an acrylic or methacrylic monomer is preferable, and one in which the polymerizable monomer includes an alkyl (meth)acrylic acid ester is more preferable.

In addition, the present composition containing (meth)acrylic resin is preferably diluted with a solvent as described below to make a coating solution, and it is preferable that the solvent to be introduced is water as the main solvent (50 mass% or more). That is, from the viewpoint of making it easy to dissolve or disperse when the coating solution is made of water, it is preferable that the polymerizable monomer has a hydrophilic group such as a hydroxyl group or a carboxyl group. Furthermore, from the viewpoint of effectively obtaining a rough structure by phase separation, it is preferable that the polymerizable monomer has a hydrophilic group such as a hydroxyl group or a carboxyl group.

Therefore, the acrylic resin is preferably a polymer formed by polymerizing a polymerizable monomer including an alkyl (meth)acrylic acid ester and a hydrophilic group-containing monomer such as a hydroxyl group-containing monomer or a carboxyl group-containing monomer.

Additionally, the acrylic resin may be an emulsion polymer, for example, obtained by polymerizing a polymerizable monomer in the presence of a surfactant.

(polyvinyl alcohol)

Polyvinyl alcohol is a compound having a polyvinyl alcohol moiety, and for example, it also includes modified compounds such as partially acetalized or butyralized polyvinyl alcohol, and conventionally known polyvinyl alcohol can be used. The degree of polymerization of polyvinyl alcohol is not particularly limited, but is usually 100 or more, preferably in the range of 300 to 40,000. When the degree of polymerization is 100 or more, it is easy to improve the water resistance of the resin layer. In addition, the degree of saponification of polyvinyl alcohol is not particularly limited, but is usually 70 mol% or more, preferably 70 to 99.9 mol%, more preferably 80 to 97 mol%, and even more preferably 86 to 95 mol%, polyvinyl acetate saponified is practically used.

(polyester resin)

As polyester resins, those containing, as main components, polycarboxylic acids and polyhydroxy compounds, for example, as follows, can be mentioned.

That is, as the polycarboxylic acid, terephthalic acid, isophthalic acid, orthophthalic acid, phthalic acid, 4,4'-diphenyldicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 2-potassium sulfoterephthalic acid, 5-sodium sulfoisophthalic acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, glutaric acid, succinic acid, trimellitic acid, trimesic acid, pyromellitic acid, trimellitic anhydride, phthalic anhydride, p-hydroxybenzoic acid, trimellitic acid monopotassium salt, and their ester-forming derivatives can be used. Examples of the polyhydroxy compounds that can be used include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, 2-methyl-1,5-pentanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, p-xylylene glycol, bisphenol A-ethylene glycol adduct, diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polytetramethylene oxide glycol, dimethylolpropionic acid, glycerin, trimethylolpropane, sodium dimethylol ethyl sulfonate, and potassium dimethylol propionate. One or more of these compounds may be appropriately selected, and a polyester resin may be synthesized by a polycondensation reaction using a conventional method.

In addition, as a part of the above polycarboxylic acid, a copolymerized sulfoisophthalic acid such as 5-sodium sulfoisophthalic acid, a sulfonic acid group is introduced into the polyester skeleton, and a neutralized and hydrophilized water is preferably used. The amount of copolymerization is usually 1 to 13 mol%, preferably 3 to 10 mol%, and more preferably 5 to 9 mol%, based on the total polycarboxylic acid. By introducing an appropriate amount of a sulfonic acid group, the hydrophilicity of the resin can be increased, and it can be made easy to form an uneven structure. In addition, the water dispersion stability can be improved.

(polymer compound with ionic conductivity)

The ionic conductive polymer compound is a polymer compound containing an ionic conductive functional group, and examples thereof include polymer compounds containing ammonium groups, polyether compounds, sulfonic acid compounds, and betaine compounds. Among these, ammonium group-containing compounds are particularly preferable from the viewpoint of having high polarity and effectively forming irregularities.

An ammonium group-containing compound refers to a compound having an ammonium group in the molecule, and is preferably a polymer compound having an ammonium group. For example, a polymer containing a monomer having an ammonium group and an unsaturated double bond as components can be used.

Specific examples of such polymers include polymers having repeating components represented by the following formula (1-1-1) as units. These may be homopolymers or copolymers, or may be copolymerized with other multiple components.

In the above formula (1-1-1), R ¹ and R ² are each independently a hydrogen atom, an alkyl group, a phenyl group, etc., and these alkyl groups and phenyl groups may be substituted with the groups shown below. The substitutable groups include, for example, a hydroxyl group, an amide group, an ester group, an alkoxy group, a phenoxy group, a naphthoxy group, a thioalkoxy group, a thiophenoxy group, a cycloalkyl group, a trialkylammonium alkyl group, a cyano group, a halogen, etc. In addition, R ¹ and R ² may be chemically bonded, and examples thereof include -(CH ₂ ) _m - (m = an integer from 2 to 5), -CH(CH ₃ )CH(CH ₃ )-, -CH=CH-CH=CH-, -CH=CH-CH=N-, -CH=CH-N=C-, -CH ₂ OCH ₂ -, -(CH ₂ ) ₂ O(CH ₂ ) ₂ -, etc.

X ^- in the above formula (1-1-1) can be appropriately selected within a range that does not impair the gist of the present invention. Examples thereof include halogen ions, sulfonates, phosphates, nitrates, alkyl sulfonates, carboxylates, and the like.

Among the above polymers, i.e., polymers containing as components a monomer having an ammonium group and an unsaturated double bond, they may be copolymerized with other monomers from the viewpoint of increasing film formation properties and obtaining a stable film.

Examples of other monomers include alkyl acrylates such as methyl acrylate, ethyl acrylate, propyl acrylate, and butyl acrylate; alkyl methacrylates such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, and butyl methacrylate; and acrylamides such as n-methylolacrylamide.

In addition, from the viewpoint of increasing polarity and effectively forming unevenness, a homopolymer having as repeating units the component represented by the above formula (1-1-1) is preferable.

In addition, the number average molecular weight of the ammonium group-containing compound is preferably 1,000 to 500,000, more preferably 2,000 to 350,000, and even more preferably 5,000 to 200,000. By setting the molecular weight to 1,000 or more, it is possible to prevent the strength of the coating film from weakening, and it becomes easy to improve heat resistance stability. In addition, by setting the molecular weight to 500,000 or less, it is possible to prevent the viscosity of the coating solution from increasing, and it becomes easy to improve handleability and applicability.

(polyurethane resin)

Polyurethane resin is a polymer compound having a urethane bond in the molecule, and is preferably water-dispersible or water-soluble. In the present invention, it may be used alone or in combination of two or more types.

In order to impart water dispersibility or water solubility, it is common and preferable to introduce a hydrophilic group such as a hydroxyl group, a carboxyl group, a sulfonic acid group, a sulfonyl group, a phosphoric acid group, or an ether group into the polyurethane resin. Among the hydrophilic groups, a carboxyl group or a sulfonic acid group is particularly preferable in terms of adhesion between the resin layer and the polyester film.

One of the methods for producing polyurethane resin is by reaction between a hydroxyl-containing compound and an isocyanate. As a hydroxyl-containing compound that can be used as a raw material, polyols are suitably used, and examples thereof include polyether polyols, polyester polyols, polycarbonate polyols, polyolefin polyols, and acrylic polyols. These compounds may be used alone or in combination.

Examples of polyether polyols include polyethylene glycol, polypropylene glycol, polyethylene propylene glycol, polytetramethylene ether glycol, and polyhexamethylene ether glycol.

As polyester polyols, those obtained by the reaction of polyhydric carboxylic acids or their acid anhydrides with polyhydric alcohols can be mentioned. As polyhydric carboxylic acids, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, sebacic acid, fumaric acid, maleic acid, terephthalic acid, isophthalic acid, etc. can be mentioned. As polyhydric alcohols, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 2-methyl-1,3-propanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 2-methyl-2,4-pentanediol, 2-methyl-2-propyl-1,3-propanediol, 1,8-octanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl-1,3-hexanediol, 2,5-dimethyl-2,5-hexanediol, 1,9-nonanediol, 2-methyl-1,8-octanediol, Examples thereof include 2-butyl-2-ethyl-1,3-propanediol, 2-butyl-2-hexyl-1,3-propanediol, cyclohexanediol, bishydroxymethylcyclohexane, dimethanolbenzene, bishydroxyethoxybenzene, alkyldialkanolamines, and lactone diol.

Examples of polycarbonate-based polyols include polycarbonate diols obtained by dealcoholization reaction from polyhydric alcohols and dimethyl carbonate, diethyl carbonate, diphenyl carbonate, ethylene carbonate, etc., such as poly(1,6-hexylene) carbonate and poly(3-methyl-1,5-pentylene) carbonate.

Among the above, polyester polyols are preferable.

As polyisocyanate compounds used for obtaining polyurethane resins, aromatic diisocyanates such as tolylene diisocyanate, xylylene diisocyanate, methylene diphenyl diisocyanate, phenylene diisocyanate, naphthalene diisocyanate, and tolidine diisocyanate; aliphatic diisocyanates having an aromatic ring such as α,α,α',α'-tetramethylxylylene diisocyanate; aliphatic diisocyanates such as methylene diisocyanate, propylene diisocyanate, lysine diisocyanate, trimethylhexamethylene diisocyanate, and hexamethylene diisocyanate; Examples thereof include alicyclic diisocyanates such as cyclohexane diisocyanate, methylcyclohexane diisocyanate, isophorone diisocyanate, dicyclohexyl methane diisocyanate, and isopropylidene dicyclohexyl diisocyanate. These may be used alone or in combination of two or more.

When synthesizing a polyurethane resin, a chain extender may be used. There are no particular restrictions on the chain extender as long as it has two or more active groups that react with isocyanate groups. In general, chain extenders having two hydroxyl groups or amino groups can be mainly used.

Examples of chain extenders having two hydroxyl groups include glycols such as aliphatic glycols such as ethylene glycol, propylene glycol, and butanediol; aromatic glycols such as xylylene glycol and bishydroxyethoxybenzene; and ester glycols such as neopentyl glycol hydroxypivalate.

Examples of chain extenders having two amino groups include aromatic diamines such as tolylenediamine, xylylenediamine, and diphenylmethanediamine; aliphatic diamines such as ethylenediamine, propanediamine, hexanediamine, 2,2-dimethyl-1,3-propanediamine, 2-methyl-1,5-pentanediamine, trimethylhexanediamine, 2-butyl-2-ethyl-1,5-pentanediamine, 1,8-octanediamine, 1,9-nonanediamine, and 1,10-decanediamine; and alicyclic diamines such as 1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane, dicyclohexylmethanediamine, 1,4-diaminocyclohexane, and 1,3-bisaminomethylcyclohexane.

((Bridge))

There is no particular limitation on the crosslinking agent selected as the compound (B), and a conventionally known crosslinking agent can be used. By using a crosslinking agent, the resin layer becomes easy to be a cured resin layer. Examples of the crosslinking agent include a melamine compound, an oxazoline compound, an epoxy compound, a carbodiimide compound, an isocyanate compound, a silane coupling compound, and the like. Among these, from the viewpoint of the ease of adjusting the unevenness formation performance by phase separation, it is preferable to use at least one of a melamine compound and an oxazoline compound as the crosslinking agent. In the present composition, the crosslinking agent may be used alone or in combination of two or more.

(melamine compound)

A melamine compound is a compound having a melamine skeleton among compounds, and examples thereof include alkylated melamine derivatives, compounds partially or completely etherified by reacting an alkylated melamine derivative with alcohol, and mixtures thereof.

Examples of alkylolation include methylolation, ethylolation, isopropylolation, n-butyrolation, and isobutyrolation. Among these, methylolation is preferable from the viewpoint of reactivity.

As alcohols used for etherification, methanol, ethanol, isopropanol, n-butanol and isobutanol are suitably used, and among these, methanol is more preferable.

In addition, as the melamine compound, either a monomer or a polymer of more than a dimer, or a mixture thereof may be used. In addition, a compound in which urea or the like is co-condensed with a portion of melamine may be used, and in order to increase the reactivity of the melamine compound, a catalyst may additionally be used in the present composition.

(Oxazoline compounds)

An oxazoline compound is a compound having an oxazoline group in the molecule, and in particular, a polymer containing an oxazoline group is preferable, and can be produced by polymerization of an addition polymerizable oxazoline group-containing monomer alone or with another monomer. Examples of the addition polymerizable oxazoline group-containing monomer include 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2-isopropenyl-2-oxazoline, 2-isopropenyl-4-methyl-2-oxazoline, and 2-isopropenyl-5-ethyl-2-oxazoline, and one kind or a mixture of two or more kinds thereof can be used. Of these, 2-isopropenyl-2-oxazoline is suitable because it is easy to obtain industrially. Other monomers are not limited as long as they are monomers copolymerizable with the addition polymerizable oxazoline group-containing monomer, and examples thereof include (meth)acrylic acid esters such as alkyl (meth)acrylates (alkyl groups include methyl groups, ethyl groups, n-propyl groups, isopropyl groups, n-butyl groups, isobutyl groups, t-butyl groups, 2-ethylhexyl groups, and cyclohexyl groups); unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, styrenesulfonic acid, and salts thereof (sodium salts, potassium salts, ammonium salts, tertiary amine salts, etc.); unsaturated nitriles such as acrylonitrile and methacrylonitrile; Examples thereof include unsaturated amides such as (meth)acrylamide, N-alkyl (meth)acrylamides, and N,N-dialkyl (meth)acrylamides (alkyl groups including methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, 2-ethylhexyl, and cyclohexyl); vinyl esters such as vinyl acetate and vinyl propionate; vinyl ethers such as methyl vinyl ether and ethyl vinyl ether; α-olefins such as ethylene and propylene; halogen-containing α,β-unsaturated monomers such as vinyl chloride and vinylidene chloride; and α,β-unsaturated aromatic monomers such as styrene and α-methylstyrene, and one or more of these monomers can be used.

In addition, the oxazoline compound may have a polyalkylene oxide chain such as a polyethylene oxide chain, and, for example, a (meth)acrylate having a polyalkylene oxide chain may be used as another monomer.

From the viewpoint of improving the adhesion of the resin layer to the polyester film, the oxazoline group amount of the oxazoline compound is preferably in the range of 0.5 to 10 mmol/g, more preferably 1 to 9 mmol/g, and even more preferably 3 to 8 mmol/g.

(epoxy compound)

Epoxy compounds are compounds having an epoxy group in the molecule, and examples thereof include condensates with hydroxyl groups or amino groups, such as epichlorohydrin, ethylene glycol, polyethylene glycol, glycerin, polyglycerin, and bisphenol A, polyepoxy compounds, diepoxy compounds, monoepoxy compounds, and glycidylamine compounds.

Examples of polyepoxy compounds include sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether, triglycidyl tris(2-hydroxyethyl) isocyanate, glycerol polyglycidyl ether, and trimethylolpropane polyglycidyl ether.

Examples of diepoxy compounds include neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, resorcin diglycidyl ether, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, and polytetramethylene glycol diglycidyl ether.

Examples of the monoepoxy compounds include allyl glycidyl ether, 2-ethylhexyl glycidyl ether, and phenyl glycidyl ether; examples of the glycidyl amine compounds include N,N,N',N'-tetraglycidyl-m-xylylenediamine, 1,3-bis(N,N-diglycidylamino)cyclohexane, and the like. From the viewpoint of improving the adhesion of the resin layer to the polyester film, a polyether-based epoxy compound is preferable.

In addition, in terms of the amount of epoxy groups, a polyepoxy compound that is trifunctional or more than bifunctional is preferable.

(carbodiimide compound)

A carbodiimide compound is a compound having a carbodiimide structure, and is a compound having one or more carbodiimide structures in the molecule. However, for better adhesion between the resin layer and the polyester film, a polycarbodiimide compound having two or more carbodiimide structures in the molecule is more preferable.

Carbodiimide compounds can be synthesized by conventionally known techniques, and generally a condensation reaction of a diisocyanate compound is used. The diisocyanate compound is not particularly limited, and both aromatic and aliphatic compounds can be used, and specific examples thereof include tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, phenylene diisocyanate, naphthalene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, cyclohexane diisocyanate, methylcyclohexane diisocyanate, isophorone diisocyanate, dicyclohexyl diisocyanate, and dicyclohexylmethane 4,4'-diisocyanate.

The content of the carbodiimide group contained in the carbodiimide compound is, in terms of the carbodiimide equivalent (the weight [g] of the carbodiimide compound for providing 1 mol of the carbodiimide group), usually in the range of 100 to 1000, preferably 250 to 800, and more preferably 300 to 700. By using it within the above range, the durability of the resin layer is improved.

In addition, in order to improve the water solubility or water dispersibility of the polycarbodiimide compound within a range that does not impair the subject matter of the present invention, a surfactant may be added, or a hydrophilic monomer such as a polyalkylene oxide, a quaternary ammonium salt of a dialkylamino alcohol, and a hydroxyalkyl sulfonic acid salt may be added and used.

(isocyanate compounds)

An isocyanate compound is a compound having an isocyanate derivative structure, represented by an isocyanate or a blocked isocyanate. Examples of the isocyanate include aromatic isocyanates such as tolylene diisocyanate, xylylene diisocyanate, methylene diphenyl diisocyanate, phenylene diisocyanate, and naphthalene diisocyanate; aliphatic isocyanates having an aromatic ring such as α,α,α',α'-tetramethylxylylene diisocyanate; aliphatic isocyanates such as methylene diisocyanate, propylene diisocyanate, lysine diisocyanate, trimethylhexamethylene diisocyanate, and hexamethylene diisocyanate; Examples thereof include alicyclic isocyanates such as cyclohexane diisocyanate, methylcyclohexane diisocyanate, isophorone diisocyanate, methylenebis(4-cyclohexyl isocyanate), and isopropylidenedicyclohexyl diisocyanate.

In addition, polymers or derivatives such as biuret compounds, isocyanurate compounds, uretdione compounds, and carbodiimide modified products of these isocyanates may also be mentioned. These may be used alone or in combination of multiple types. Among the above isocyanates, aliphatic isocyanates or alicyclic isocyanates are more preferable than aromatic isocyanates in order to avoid yellowing due to ultraviolet rays.

When used in the state of blocked isocyanate, examples of the blocking agent include bisulfite salts; phenol compounds such as phenol, cresol and ethylphenol; alcohol compounds such as propylene glycol monomethyl ether, ethylene glycol, benzyl alcohol, methanol and ethanol; active methylene compounds such as methyl isobutanoyl acetate, dimethyl malonate, diethyl malonate, methyl acetoacetate, ethyl acetoacetate and acetylacetone; mercaptan compounds such as butyl mercaptan and dodecyl mercaptan; lactam compounds such as ε-caprolactam and δ-valerolactam; amine compounds such as diphenylaniline, aniline and ethyleneimine; acid amide compounds such as acetanilide and acetic acid amide; Examples of oxime compounds include formaldehyde oxime, acetaldoxime, acetone oxime, methyl ethyl ketone oxime, and cyclohexanone oxime, and these may be used alone or in combination of two or more.

In addition, the isocyanate compound may be used alone or as a mixture or combination with various polymers. In terms of improving the dispersibility or crosslinking property of the isocyanate compound, it is preferable to use a mixture or combination of a polyester resin or a polyurethane resin.

(silane coupling compound)

A silane coupling compound is an organosilicon compound having an organic functional group and a hydrolyzable group such as an alkoxy group in one molecule. Examples thereof include epoxy group-containing compounds such as 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; vinyl group-containing compounds such as vinyltrimethoxysilane and vinyltriethoxysilane; styryl group-containing compounds such as p-styryltrimethoxysilane and p-styryltriethoxysilane; (Meth)acryl group-containing compounds such as 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 3-(meth)acryloxypropylmethyldimethoxysilane, and 3-(meth)acryloxypropylmethyldiethoxysilane; Amino group-containing compounds such as 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldiethoxysilane, 3-triethoxysilyl-N-(1,3-dimethylbutylidene)propylamine, N-phenyl-3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltriethoxysilane; isocyanurate group-containing compounds such as tris(trimethoxysilylpropyl)isocyanurate, tris(triethoxysilylpropyl)isocyanurate; Examples thereof include mercapto group-containing compounds such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, and 3-mercaptopropylmethyldiethoxysilane.

The content of compound (B) in the present composition is, as a proportion of the total nonvolatile components in the present composition, preferably in the range of 5 to 95 mass%, more preferably 10 to 80 mass%, and even more preferably 20 to 60 mass%. By setting the content to 10 mass% or more, it is possible to achieve both formation of a roughened structure by phase separation and improvement of the coatability when the present composition is used as a coating liquid. In addition, by setting the content to 95 mass% or less, the content of one resin can be secured, and the performance of forming roughness by phase separation can be appropriately adjusted.

(((especially desirable form)))

As the compounds (A) and (B) included in the present composition, a combination of (a) a low-polarity compound and a binder resin, (b) a low-polarity compound and a cross-linking agent, and (c) a low-polarity compound, a binder resin, and a cross-linking agent is particularly preferable, and the combination of (c) is particularly preferable.

(((Compound (C))))

When the compound (B) contains a cross-linking agent, the composition may additionally contain a (C) cross-linking catalyst (compound (C)).

The above (C) crosslinking catalyst is used to increase the reactivity of the crosslinking agent, and various known catalysts can be used. For example, amine compounds, salts of amine compounds, organic acids such as aromatic sulfonic acid compounds such as p-toluenesulfonic acid or phosphoric acid compounds and their salts, imine compounds, amidine compounds, guanidine compounds, organometallic compounds, metal salts such as zinc stearate, zinc myristate, aluminum stearate, or calcium stearate, etc. Among these, amine compounds, salts of amine compounds, and p-toluenesulfonic acid are preferable, and amine compounds and salts of amine compounds are more preferable.

When the composition contains a crosslinking catalyst, the content of the crosslinking catalyst (compound (C)) in the composition is preferably in the range of 0.01 to 5 mass%, more preferably 0.1 to 4 mass%, and even more preferably 1 to 3 mass%, as a proportion of the total nonvolatile components in the composition. By setting the content in this range, the reduction in the usable time can be suppressed, and furthermore, the performance of forming irregularities by phase separation becomes sufficient.

(((Compound (D))))

The present composition may contain (D) fine particles (compound (D)). By using fine particles together, it becomes possible to further improve the surface hardness of the convex portion in the resin layer having an uneven structure. By increasing the surface hardness of the convex portion, even when the present laminated polyester film is made into a roll, the convex portion on the surface of the resin layer is less likely to be deformed, so that a good roll appearance can be obtained. In particular, when the present composition is composed of only a resin, since the convex portion is flexible, when made into a roll, the convex portion may be deformed and the air passage may be distorted, so that the original excellent handleability may not be sufficiently exhibited. Therefore, there is also a form in which it is preferable to contain fine particles.

As the above (D) fine particles, for example, in addition to inorganic particles such as silica, calcium carbonate, magnesium carbonate, barium carbonate, calcium sulfate, calcium phosphate, magnesium phosphate, kaolin, aluminum oxide, and titanium oxide, crosslinked polymers such as crosslinked silicone resin particles, crosslinked acrylic resin particles, crosslinked styrene-acrylic resin particles, and crosslinked polyester particles, and organic particles such as calcium oxalate and ion exchange resins can be mentioned. Among these, silica and aluminum oxide are preferable.

The average particle diameter of the above (D) fine particles is preferably 1 to 100 nm, more preferably 2 to 60 nm, and even more preferably 3 to 30 nm. When the average particle diameter is in this range, the occurrence of coarse protrusions due to particle aggregation or contamination of the process due to particle dropout can be suppressed, and it becomes easy to obtain the desired fine uneven structure.

In addition, the method for measuring the average particle diameter of the fine particles includes a method for calculating from the specific surface area and particle density measured by a specific surface area measuring device, a method for calculating the particle diameter by observing with a transmission electron microscope (TEM) or a scanning electron microscope (SEM), and a method for obtaining from measurement by a dynamic light scattering method. The average particle diameter of the fine particles can be measured by a suitable method.

When the composition contains fine particles, the content of the fine particles (compound (D)) in the composition is preferably in the range of 1 to 50 mass%, more preferably 10 to 45 mass%, and even more preferably 22 to 40 mass%, as a proportion of the total nonvolatile components in the composition. By setting the content in this range, the surface hardness of the convex portion can be improved while obtaining the desired fine uneven structure.

(((Other ingredients)))

In addition, in a range that does not impair the subject matter of the present invention, in addition to the above components, additives such as a defoaming agent, a coating improving agent, a surfactant, a thickener, an organic lubricant, an ultraviolet absorber, an antioxidant, a foaming agent, a dye, a pigment, etc. may also be appropriately blended.

(((menstruum)))

The present composition may be diluted with a solvent to form a coating solution. That is, the present composition may be applied as a liquid coating solution to, for example, the present polyester film, and dried or cured as necessary to form a resin layer.

In addition, each component (compounds (A) and (B), optionally added (C) cross-linking catalyst and (D) fine particles, other components, etc.) constituting the present composition may be dissolved in a solvent or dispersed in a solvent.

When used as a coating solution, the concentration of the total nonvolatile components of the composition in the coating solution is preferably 0.1 to 50 mass%. When it is 0.1 mass% or more, a resin layer of a desired thickness can be efficiently formed. On the other hand, when it is 50 mass% or less, the viscosity at the time of coating can be suppressed, thereby improving the appearance of the resin layer, and also increasing the stability in the coating solution.

As the solvent, there is no particular limitation, and both water and organic solvents can be used. From the viewpoint of environmental protection, it is preferable to use water as the main solvent (50 mass% or more of the total solvent) as an aqueous coating solution. Regarding the water content, it is preferably 60 mass% or more, more preferably 70 mass% or more. The aqueous coating solution may contain a small amount of organic solvent. The specific amount of the organic solvent may be equal to or less than the amount of water in mass terms, but for example, it is preferably equal to or less than 50 mass%, preferably equal to or less than 40 mass%, more preferably equal to or less than 30 mass% of the solvent.

Examples of organic solvents to be used in combination with water include alcohols such as ethanol, isopropanol, ethylene glycol, and glycerin; ethers such as ethyl cellosolve, t-butyl cellosolve, propylene glycol monomethyl ether, and tetrahydrofuran; ketones such as acetone and methyl ethyl ketone; esters such as ethyl acetate; and amines such as dimethyl ethanolamine. These can be used singly or in combination. By appropriately selecting and containing these organic solvents in an aqueous coating solution as needed, the stability and coatability of the coating solution can sometimes be improved.

In addition, when only an organic solvent is used as the solvent, examples of the organic solvent include aromatic hydrocarbons such as toluene; aliphatic hydrocarbons such as hexane, heptane, and isooctane; esters such as ethyl acetate and butyl acetate; ketones such as ethyl methyl ketone and isobutyl methyl ketone; alcohols such as ethanol and 2-propanol; ethers such as diisopropyl ether and dibutyl ether, etc. These may be used alone, or multiple types may be mixed and used, taking into consideration solubility, coatability, and boiling point.

It can be assumed that, among the resin layers, unreacted substances, compounds after reaction, or mixtures thereof of each component constituting the composition (compounds (A) and (B), optionally added (C) cross-linking catalyst and (D) fine particles, other components, etc.) are present.

Additionally, analysis of each component in the resin layer can be performed using, for example, TOF-SIMS, ESCA, fluorescence X-ray, etc.

<Hansen solubility parameters>

Each component (compound (A) and (B)) constituting the present composition can also be explained by the Hansen solubility parameter (HSP). More specifically, the uneven structure possessed by the present resin layer is a fine shape formed by phase separation as described above, but it is possible to explain this phase separation using HSP.

The Hansen solubility parameter (HSP) is an index of solubility, which is the degree to which a substance dissolves in another substance. The HSP is a solubility parameter introduced by Hildebrand, which is divided into three components: the dispersion term δd, the polar term δp, and the hydrogen bonding term δh, and expressed in a three-dimensional space.

The dispersion term δd represents the effect due to dispersion force, the polarity term δp represents the effect due to dipole force, and the hydrogen bond term δh represents the effect due to hydrogen bond force, and they are expressed as follows.

Also, each unit is ㎫ ^0.5 .

δd: Energy derived from intermolecular dispersion forces

δp: Energy derived from intermolecular polarity

δh: Energy derived from hydrogen bonding between molecules

The definition and calculation of HSP are described in the following literature.

Charles M. Hansen, Hansen Solubility Parameters: A Users Handbook (CRC Press, 2007).

Each of the dispersion terms reflects the London dispersion force, the polarity term reflects the dipole moment, and the hydrogen bond term reflects the action of water, alcohol, etc.

Also, it can be determined that vectors with similar HSP properties have high solubility, and the similarity of vectors can be determined from the HSP distance (HSP distance).

In the present invention, the HSP [δd, δp, δh] of the resin (corresponding to compounds (A) and (B) as described above) can be used to evaluate the solubility of the HSP in various solvents as a base, and the solvent in which the resin dissolves is a good solvent, and the solvent in which the resin is insoluble or swells is a poor solvent, thereby calculating the interaction sphere and the HSP at the center of the interaction sphere.

For calculation, for example, the commercially available Hansen solubility parameter calculation software HSPiP (Hansen Solubility Parameters in Practice) can be used, and the thresholds for good and poor solvents can be determined so that the fitting value of the calculated interaction sphere is closest to 1. For accurate measurement, it is sufficient that the solvents used for measurement each have various HSPs [δD, δP, δH], and the specific types of solvents are as shown in Table 1. According to Table 1, a solubility test is conducted with 18 or more solvents, and a good solvent or poor solvent judgment is made for each solvent type. In addition, "≥1" in the table means that measurement is performed for 1 or more solvents, and "≥2" means that measurement is performed for 2 or more solvents.

In addition, the HSP[δd, δp, δh] of the resin can be calculated by the Y-MB (Yamamoto Molecular Break) function of HSPiP if the chemical structure is clear, and can be obtained by actual measurement using a conventionally known method if the chemical structure is not clear.

In addition, the resin HSP in the resin layer can be obtained by dissolving the formed resin layer in a suitable solvent, separating each component, and then using the same method as above.

It is preferable that compounds (A) and (B) include at least one selected from compound (A) and at least one selected from compound (B) that satisfy the relationship of the following formula (1-1-2).

HSP distance={4×(δd ₁ -δd ₂ ) ² +(δp ₁ -δp ₂ ) ² +(δh ₁ -δh ₂ ) ² } ^0.5 ≥5.0 … (1-1-2)

Wherein, δd ₁ , δp ₁ and δh ₁ represent δd, δp and δh of compound (A), respectively, in the Hansen solubility parameters [δd, δp, δh], and δd ₂ , δp ₂ and δh ₂ represent δd, δp and δh of compound (B), respectively. In addition, δp ₁ ≤ δp ₂ .

The HSP distance defined by the above formula (1-1-2) is 5.0 or more, preferably 6.0 or more, more preferably 7.0 or more, and even more preferably 8.0 or more. When the HSP distance is in this range, a composition including a resin having different compatibility is likely to cause phase separation, so that even if the resin layer is a thin film, it can have a desired fine uneven structure. The HSP distance defined by the above formula (1-1-2) is not particularly limited, but is preferably 25.0 or less, more preferably 23.0 or less, and even more preferably 21.0 or less.

In order to satisfy the relationship of the above formula (1-1-2), the compounds (resins) used as compounds (A) and (B) are not particularly limited, and in the case where two types of resins are selected, one type each for each compound, at least one combination among the conceivable combinations is sufficient as long as the two types of resins satisfy the relationship of the above formula (1-1-2).

For example, if there are two types of compounds (A) included in the present composition, namely, Resin A-1 and Resin A-2, and if there are two types of compounds (B) included in the present composition, namely, Resin B-1 and Resin B-2, then the possible combinations for selecting two types of resins for compounds (A) and (B) are four types: Resin A-1 and Resin B-1, Resin A-1 and Resin B-2, Resin A-2 and Resin B-1, and Resin A-2 and Resin B-2. Therefore, the meaning above is that at least one of the four types satisfies the relationship of the above formula (1-1-2).

In other words, the combination in which the HSP distance between two of the four resins becomes the longest (the longest distance between two resins) must satisfy the relationship in the above equation (1-1-2).

Next, the HSPs of compounds (A) and (B) exemplified above are each described.

(((HSP of compound (A))))

From the viewpoint of forming a fine roughening structure by phase separation, the polarity term δp ₁ of the compound (A) is preferably 9.0 MPa ^0.5 or less, more preferably 8.0 MPa ^0.5 or less, and even more preferably 7.0 MPa ^0.5 or less. When the value of the polarity term δp ₁ is in this range, the polarity of the compound (A) can be lowered, the relationship of the above formula (1-1-2) can be easily satisfied, and as a result, the desired roughening structure can be easily formed. The value of the polarity term δp ₁ of the compound (A) is not particularly limited, but is preferably 1.0 MPa ^0.5 or more, more preferably 2.0 MPa ^0.5 or more. The polarity term δp ₁ of the compound (A) is usually equal to or less than the polarity term δp ₂ of the compound (B).

In addition, the hydrogen bond term δh ₁ of the compound (A) is preferably 15.0 MPa ^0.5 or less, more preferably 12.0 MPa ^0.5 or less, and even more preferably 9.0 MPa ^0.5 or less. On the other hand, the hydrogen bond term δh ₁ of the compound (A) is preferably 1.0 MPa ^0.5 or more, more preferably 3.0 MPa ^0.5 or more, and even more preferably 5.0 MPa ^0.5 or more. When it is equal to or more than the lower limit, the hydrogen bond term of the compound (A) can be prevented from becoming too low, and therefore, the interaction with the compound (B) can be prevented from becoming low, which can lead to separation of layers or the like, and thus not forming an uneven shape.

In addition, the dispersion term δd ₁ of compound (A) is not particularly limited, but is preferably 6.0 MPa ^0.5 or more, more preferably 8.0 MPa ^0.5 or more, and even more preferably 10.0 MPa ^0.5 or more.

When the values of the hydrogen bond term δh ₁ and/or the dispersion term δd ₁ are within these ranges, it becomes easy to satisfy the relationship of the above formula (1-1-2).

In addition, when the present composition contains two or more compounds (A), at least one compound (A) may have the value of the above-mentioned polar term δp ₁ , but all compounds (A) may have the values of the above-mentioned polar term δp _1. The same applies to the hydrogen bonding term δh ₁ and the dispersion term δd ₁ .

(((HSP of compound (B))))

From the viewpoint of being able to contribute to the formation of a fine uneven structure by phase separation and also improving the applicability when the composition is used as a coating liquid, the hydrogen bond term δh ₂ of the compound (B) is preferably 7.5 MPa ^0.5 or more, more preferably 8.0 MPa ^0.5 or more, and even more preferably 9.0 MPa ^0.5 or more. When the value of the hydrogen bond term δh ₂ is in this range, the hydrophilicity of the compound (B) can be increased, and the applicability can be improved. In addition, it becomes easy to satisfy the relationship (1-1-2) above, and as a result, it becomes easy to form a desired uneven structure.

In addition, the hydrogen bond term δh ₂ of the compound (B) is preferably 25.0 MPa ^0.5 or less, more preferably 23.0 MPa ^0.5 or less, and even more preferably 20.3 MPa ^0.5 or less. By setting the value of the hydrogen bond term δh ₂ to a certain value or less, the hydrophilicity is not increased too much, thereby preventing the coating film from absorbing water and softening, and reducing the roughness strength, and making it easy to improve the slipperiness.

In addition, the polarity term δp ₂ of the compound (B) is preferably 7.0 MPa ^0.5 or more, more preferably 8.0 MPa ^0.5 or more, even more preferably 9.0 MPa ^0.5 or more, and the dispersion term δd ₂ is not particularly limited, but is preferably 6.0 MPa ^0.5 or more, more preferably 8.0 MPa ^0.5 or more, even more preferably 10.0 MPa ^0.5 or more. When the values of the hydrogen bond term δh ₂ and/or the dispersion term δd ₂ are in these ranges, it becomes easy to satisfy the relationship of the above formula (1-1-2).

In addition, when the present composition contains two or more compounds (B), at least one compound (B) may have the value of the hydrogen bonding term δh ₂ described above, but all of the compounds (B) may have the value of the hydrogen bonding term δh ₂ described above. The same applies to the polarity term δp ₂ and the dispersion term δd ₂ .

Although the present resin layer essentially contains at least two kinds of resins, one kind selected from compound (A) and one kind selected from compound (B), it is preferable to contain three or more kinds of resins from the viewpoints of making it easier to adjust the uneven shape and also being able to control the adhesion with the polyester film and the coating strength. In that case, it is preferable to consider not only the maximum distance between the two kinds of resins but also the distance from the resin of the third component. Furthermore, the resin of the third component may be selected from compound (A), may be selected from compound (B), or may be selected from another compound, but it is preferable that it is selected from at least compound (B).

As a more preferable embodiment, when the polarity term δp ₁ of the compound (A) is 9.0 MPa ^0.5 or less, and a resin having an HSP distance of 19.0 or more for the compound (A) is included, a resin having an HSP distance of 15.0 or less can be included. The HSP distance in this case is calculated by the relationship defined in the above formula (1-1-2).

If the above conditions can be satisfied, a fine roughening structure can be expressed more effectively by phase separation. From this viewpoint, it is more preferable to include a resin having an HSP distance of 7.0 or more for a compound (A) having a polarity term δp ₁ of 9.0 MPa ^0.5 or less, and even more preferably, a resin having an HSP distance of 8.0 or more is included. Furthermore, when a resin having an HSP distance of 19.0 or more is included, it is more preferable to further include a resin having an HSP distance of 15.0 or less, and even more preferably, a resin having an HSP distance of 13.0 or less is included.

<Method of forming a resin layer>

Next, a method for forming a resin layer constituting the laminated polyester film is described.

The present resin layer is formed by applying the present composition to a polyester film and, if necessary, performing treatments such as drying, curing, and heat treatment on the applied composition. At least heat treatment is preferably performed. The method for applying the resin composition is not particularly limited, and for example, a conventionally known coating method such as reverse gravure coat, direct gravure coat, roll coat, die coat, bar coat, or curtain coat can be used.

In addition, as a method of forming a resin layer, there are inline coating and offline coating. The method of heat-treating the applied resin composition is not particularly limited, and for example, in the case of forming a resin layer by offline coating, it is preferable to perform heat treatment at 80 to 200°C for 3 to 40 seconds, preferably at 100 to 180°C for 3 to 40 seconds. On the other hand, in the case of forming a resin layer by inline coating, it is preferable to perform heat treatment at 70 to 280°C for 3 to 200 seconds.

In addition, the heat treatment may be performed in two or more stages with different temperatures within the above temperature range. At least part of the heat treatment may be performed by heating during stretching. In addition, drying and curing may be performed simultaneously by heating in the above heat treatment.

In the present invention, it is preferable that the resin layer is formed by inline coating, which treats the film surface during the film forming process of a polyester film.

In-line coating is a method of performing coating within the process of manufacturing polyester film, and specifically, it is a method of performing coating at any stage from melting and extruding polyester to stretching, heat setting, and winding. Typically, coating is performed on any of the following: an unstretched sheet obtained by melting and rapid cooling, a stretched uniaxially stretched film, a biaxially stretched film before heat setting, and a film after heat setting and before winding.

Although not limited thereto, for example, in sequential biaxial stretching, a method of coating a uniaxially stretched film stretched in the longitudinal direction (vertical direction) and then stretching in the transverse direction is excellent. According to this method, since film forming and resin layer formation can be performed simultaneously, there is an advantage in manufacturing cost, and in addition, in order to perform stretching after coating, the thickness of the resin layer can be changed by the stretching ratio, and thin film coating can be performed more easily compared to an offline coating film.

In addition, by providing a resin layer on the film before stretching, the resin layer can be stretched together with the polyester film, thereby firmly adhering the resin layer to the polyester film.

In addition, in the production of a biaxially oriented polyester film, by stretching the film while holding the ends of the film with clips or the like, the film can be restrained in the vertical and horizontal directions, and in the subsequent heat treatment (heat setting process), a high temperature can be applied while maintaining flatness without wrinkles or the like.

For this reason, since the heat treatment performed after application can be performed at a high temperature that cannot be achieved by other methods, the film forming property of the resin layer is improved, and the resin layer and the polyester film can be more firmly adhered. Furthermore, a strong resin layer can be formed, and performances such as migration resistance and moisture resistance to various functional layers that can be formed on the resin layer can be improved.

In addition, regardless of whether it is offline coating or inline coating, heat treatment and active energy ray irradiation such as ultraviolet irradiation may be used in combination as needed. The polyester film constituting the present laminated polyester film may be subjected to surface treatment such as corona treatment or plasma treatment in advance.

The amount of the nonvolatile component applied to the resin layer is preferably 0.005 to 0.95 g/m2, more preferably 0.01 to 0.5 g/m2, and even more preferably 0.02 to 0.2 g/m2. When the amount of application is within this range, a fine rough structure can be formed by phase separation.

In addition, the amount of application can be calculated from the concentration of nonvolatile components of the application liquid, the amount of application before drying derived from the amount of application liquid consumed, the transverse elongation ratio, etc.

In addition, the amount of nonvolatile component applied is the amount applied to the laminated polyester film, and for example, in the case of drying and stretching, it is the amount applied after drying and stretching.

<<<Properties of laminated polyester film>>>

The load length ratio (Rmr(80)) of the roughness curve at the cut level of 80% of the resin layer surface of the present laminated polyester film is 76% or less.

The load length ratio (Rmr(c)) is one of the line roughness parameters (JIS B 0601), and represents the ratio of the load length ML(c) of the contour curve element at the cutting level c (height% or ㎛) to the evaluation length Ln, and is obtained from the following equation (1-1-3).

Here, the inventors of the present invention considered that the load length ratio (Rmr(80)) is effective as an index representing the uneven distribution of the uneven structure. For example, when the concave distribution is large, the load length ratio (Rmr(80)) becomes small, and when the convex distribution is large, the load length ratio (Rmr(80)) becomes large. When the load length ratio (Rmr(80)) is small, the gap between films when the film is wound into a roll shape becomes large, the ease of air escape is improved, and the winding property, etc. can be improved.

The load length ratio (Rmr(80)) of the roughness curve at the cutting level of 80% is, as described above, 76% or less, preferably 70% or less, more preferably 65% or less, and particularly preferably 58% or less. The lower limit is not particularly limited and is about 1%, preferably 4%, and more preferably 6%.

The above load length ratio (Rmr(80)) can be adjusted by the composition or content of the composition.

In addition, the load length ratio (Rmr(50)) of the roughness curve at the cutting level of 50% of the resin layer surface is preferably 60% or less, more preferably 40% or less, and even more preferably 20% or less. The lower limit is not particularly limited and is about 1%, preferably 3%, and more preferably 5%.

Here, the inventors of the present invention thought that considering the load length ratio (Rmr(50)) in addition to the load length ratio (Rmr(80)) is more effective as an index representing the uneven distribution of the uneven structure. For example, even in the case of the same load length ratio (Rmr(80)) value, when the load length ratio (Rmr(50)) value is small, the convex shape is thin, and when the load length ratio (Rmr(50)) value is large, the convex shape is thick. Therefore, when the load length ratio (Rmr(50)) is small, the uneven shape becomes finer, and when the film is wound into a roll, the gap created between the films becomes larger, so that the easiness of air escape is improved, and the winding property, etc. can be improved.

The above load length ratio (Rmr(50)) can also be adjusted by the composition or content of the composition.

In addition, the arithmetic mean roughness (Ra) of the surface of the resin layer is preferably 5 nm or more, more preferably 20 nm or more, further preferably 30 nm or more, and particularly preferably 35 nm or more. The upper limit is not particularly limited, but is preferably 600 nm, more preferably 400 nm, and further preferably 200 nm. When the arithmetic mean roughness (Ra) is 5 nm or more, it can be said that the resin layer has a fine uneven structure, and the handleability of the laminated polyester film becomes good. In addition, when the arithmetic mean roughness (Ra) is 600 nm or less, it can be said that the uneven structure of the resin layer has a sufficiently fine shape.

Arithmetic mean roughness (Ra) is one of the linear roughness parameters (JIS B 0601) and represents the average value of the average elevation difference in the mean plane.

That is, when a portion of the standard length L is extracted, and the average line of this extracted portion is represented as the x-axis and the direction of the vertical magnification is represented as the y-axis, the roughness curve is obtained by the following equation (1-1-4).

In addition, the ten-point average roughness (Rzjis) of the surface of the resin layer is preferably 28 nm or more, more preferably 70 nm or more, further preferably 90 nm or more, and particularly preferably 120 nm or more. The upper limit is not particularly limited, but is preferably 800 nm, more preferably 600 nm, and further preferably 500 nm. When the ten-point average roughness (Rzjis) is 28 nm or more, it can be said that the resin layer has a sufficient uneven structure. In addition, when the ten-point average roughness (Rzjis) is 800 nm or less, it can be said that the uneven structure of the resin layer has a sufficiently fine shape.

The ten-point average roughness (Rzjis) is one of the line roughness parameters (JIS B 0601), and represents the sum of the average of the fifth from the maximum peak height (Zp) of the contour curve and the average of the fifth from the deepest valley depth (Zv) in the reference length L, and is obtained from the following equation (1-1-5).

The above arithmetic mean roughness (Ra) and ten-point mean roughness (Rzjis) can be adjusted by the composition, content, etc. of the composition.

In addition, the load length ratio (Rmr(80)), load length ratio (Rmr(50)), arithmetic mean roughness (Ra) and ten-point average roughness (Rzjis) of the resin layer surface are measured by the method described in the examples using an atomic force microscope (scanning probe microscope). If the measurement is by an atomic force microscope (scanning probe microscope), it is possible to grasp a finer structure of the surface, and it becomes possible to obtain a value that strongly reflects the effect by the resin layer.

The surface arithmetic mean roughness (Sa) of the surface opposite to the resin layer surface of the present laminated polyester film is preferably 15 nm or less, more preferably 9 nm or less, and even more preferably 5 nm or less. On the other hand, from the viewpoint of film handleability, the arithmetic mean roughness (Sa) is preferably 0.3 nm or more.

The average surface roughness (Sa) is one of the surface roughness parameters (ISO 25178), and is a three-dimensional extension of the two-dimensional Ra (arithmetic mean roughness of a line). It is calculated by dividing the volume of the area surrounded by the surface shape curve and the average plane by the measurement area, and is obtained from the following equation (1-1-6).

When the surface is the XY plane and the height direction is the Z axis, A: defined area (the entire image), Z(x,y): height from the plane of height 0 of the image point (x,y), it is expressed as follows.

In addition, the maximum peak height (Sp) of the surface opposite to the resin layer surface of the present laminated polyester film is preferably 800 nm or less, more preferably 500 nm or less, and even more preferably 100 nm or less. Meanwhile, the lower limit of the maximum peak height (Sp) is not particularly limited, but from the viewpoint of handleability of the film, it is preferably 5 nm or more, more preferably 10 nm or more, and even more preferably 20 nm or more.

The maximum height (Sp) is one of the surface roughness parameters (ISO 25178), and represents the maximum value of the height from the average plane of the surface, and is expressed as in the following equation (1-1-7).

When the present laminated polyester film is used as a release film for forming a green sheet of a laminated ceramic capacitor, a substrate for interlayer insulating resin release, a substrate for dry film resist, etc., processing utilizing the smoothness of the film is performed. At that time, it is preferable that at least one side of the present laminated polyester film is smooth. Furthermore, if the arithmetic mean roughness (Sa) or maximum peak height (Sp) of the surface opposite to the surface on which the resin layer is formed is within the above range, it can be said to be smooth, and since transfer of unevenness or protrusions on the film surface is small, good processing is possible.

In addition, the arithmetic mean roughness (Sa) and maximum protrusion height (Sp) of the surface opposite to the resin layer surface can be measured by a non-contact surface roughness meter utilizing optical interference, and specifically, can be measured by the method described in the examples.

The coefficient of static friction between the surface of the resin layer of the present laminated polyester film and the opposite surface is preferably 1.0 or less, more preferably 0.8 or less, and even more preferably 0.6 or less.

When this laminated polyester film is wound into a roll, the friction coefficient between the surface of the resin layer and the opposite surface is important because the surface and the opposite surface of the resin layer come into contact.

Accordingly, when the static friction coefficient is within this range, the uneven structure of the resin layer improves the slipperiness and the handling properties of the laminated polyester film improve.

In addition, the static friction coefficient can be measured by the method described in the examples.

As an index for evaluating the handling properties such as the windability of the present laminated polyester film, the air leakage index can be used. If the air leakage index is low, when the present laminated polyester film is rolled up, the air that has been rolled up is likely to escape, and defects in the appearance of the roll such as wrinkles or mismatch of the end faces can be prevented. In addition, if the air leakage index is high, the air that has been rolled up escapes after a sufficient period of time, especially during conveyance, and the film may be misaligned in the direction of the winding core, or the misalignment may cause scratches, which can be a problem.

The air leakage index should be, for example, less than 130,000 seconds. If it is less than 130,000 seconds, it can be said to have certain handling properties.

In addition, the air leakage index can be improved not only by the uneven structure of the resin layer, but also by the roughness of the smooth surface of the polyester film. As described above, it is preferable that the arithmetic mean roughness (Sa) of the surface opposite to the surface on which the resin layer is formed (i.e., the smooth surface) satisfies either or both of 15 nm or less and a maximum peak height (Sp) of 800 nm or less, but in this case, the air leakage index is preferably 10,000 seconds or less, more preferably 8,000 seconds or less, and even more preferably 7,000 seconds or less. Here, the opposite surface may be a film surface used for processing when the present laminated polyester film is used for various purposes, such as a release film for forming a green sheet of a laminated ceramic capacitor, a base material for an interlayer insulating resin release, and a base material for a dry film resist, and, for example, as described below, various materials may be applied or laminated thereon.

On the other hand, when more precise processing is required, as described above, it is more preferable that the arithmetic mean roughness (Sa) of the opposite side (i.e., the smooth surface of the film used for processing) is 9 nm or less and the maximum peak height (Sp) is 500 nm or less, or both. In this case, the air leakage index is preferably 130,000 seconds or less, more preferably 100,000 seconds or less, even more preferably 70,000 seconds or less, and particularly preferably 50,000 seconds or less. In this way, when the smooth surface of the film is very highly smooth, more precise processing can be performed by utilizing the smoothness of the film, and in addition, the air leakage index is improved within the above range by the uneven structure of the resin layer, so that the windability becomes good and the handling property of the laminated polyester film becomes good.

In this way, since the air leakage index depends on the degree of smoothness of the surface opposite to the surface on which the resin layer is formed, it is preferable to set it to a numerical range corresponding to each degree of smoothness. More specifically, it is preferable to set the air leakage index to the above numerical range, because the effect of improving the handling property due to the uneven structure of the resin layer is obtained.

Additionally, the air leakage index can be measured by the method described in the examples.

<<<Uses of laminated polyester films>>>

This resin layer is characterized by being composed of a resin composition containing a specific compound and having a specific roughness structure, thereby forming a phase-separated structure even in a thin film, thereby being able to express a fine roughness structure. In addition, it is characterized by focusing on the load length ratio (Rmr(80)) that represents the roughness structure's roughness distribution.

By this design concept, it has become possible to precisely control the fine roughness structure, which is difficult to achieve with conventional particle mixing type film manufacturing methods. In addition, by having a specific roughness structure, it is possible to improve the air permeability even in a thin film, making it possible to provide a laminated polyester film with excellent handling properties.

This laminated polyester film can be used for various purposes for the purpose of improving handling properties, and the uses are not particularly limited.

Among these, as described above, because of its fine uneven structure, when used for sheet molding, it has the advantage of exhibiting good windability and being unlikely to cause wrinkles even when winding a highly smooth film into a roll shape, and can be suitably used as a polyester film for sheet molding. Examples of the polyester film for sheet molding include various release/process uses such as green sheet molding of multi-layer ceramic capacitors (MLCC), interlayer insulating resins, dry film resists (DFRs), and multilayer circuit boards. The present laminated polyester film is used as a support, for example, in release/process uses.

The polyester film for sheet forming may be used, for example, in a process for forming various sheets such as green sheets by applying or laminating various materials on at least one side of the film. When the resin layer is provided on only one side, the various materials are preferably applied or laminated on the film side (opposite side) opposite to the side on which the resin layer is provided, but may be applied or laminated on the film side on which the resin layer is provided. Furthermore, in the polyester film for sheet forming, a release layer or the like may be appropriately provided on the film side opposite to the side on which the resin layer is provided.

<<<Other aspects of laminated polyester film>>>

As another embodiment of the present laminated polyester film, the following composition may be exemplified.

A laminated polyester film comprising a polyester film and a resin layer formed by a resin composition on at least one side of the polyester film,

The above resin layer has a rough structure,

The above resin composition comprises two or more types of resins,

A laminated polyester film in which at least two types of resins among the above two or more types of resins, one of which is a first resin and the other is a second resin, satisfy the relationship of the following formula (1-2-1).

HSP distance={4×(δd ₁ -δd ₂ ) ² +(δp ₁ -δp ₂ ) ² +(δh ₁ -δh ₂ ) ² } ^0.5 ≥5.0 … (1-2-1)

(Wherein, δd ₁ , δp ₁ and δh ₁ represent δd, δp and δh of the first resin, respectively, in the Hansen solubility parameters [δd, δp, δh], and δd ₂ , δp ₂ and δh ₂ represent δd, δp and δh of the second resin, respectively. In addition, δp ₁ ≤ δp ₂ .)

That is, the present resin layer is, in another aspect, a resin composition for forming the present resin layer, which includes two or more kinds of resins, and at least two kinds of resins among the two or more kinds of resins include resins that satisfy the relationship of the following formula (1-2-1) when one side is a first resin and the other side is a second resin.

HSP distance={4×(δd ₁ -δd ₂ ) ² +(δp ₁ -δp ₂ ) ² +(δh ₁ -δh ₂ ) ² } ^0.5 ≥5.0 … (1-2-1)

Here, δd ₁ , δp ₁ and δh ₁ represent δd, δp and δh of the first resin, respectively, in the Hansen solubility parameters [δd, δp, δh], and δd ₂ , δp ₂ and δh ₂ represent δd, δp and δh of the second resin, respectively.

In addition, for the first resin and the second resin, among the two types of resins, the one having a smaller value of the polarity term δp is designated as the first resin, and the one having a larger value of the polarity term δp is designated as the second resin. That is, δp ₁ ≤ δp _2. However, when the values of the polarity terms δp of the two types of resins are the same, the one having a smaller value of the hydrogen bonding term δh is designated as the first resin, and when the values of the hydrogen bonding terms δh are also the same, the one having a smaller value of the dispersion term δd is designated as the first resin.

The two or more resins included in the above resin composition are not particularly limited, and in the case where two resins are selected from all resins included in the resin composition, the two resins by at least one combination among the conceivable combinations may satisfy the relationship of the above formula (1-2-1).

For example, if the total resins included in the present composition are three types, namely, resin A, resin B, and resin C, then the combinations that can be considered when selecting two types of resins from among the total resins are three types, namely, resin A and resin B, resin B and resin C, and resin C and resin A. Therefore, what is meant above is that at least one of the three types satisfies the relationship of the above formula (1-2-1).

In other words, the combination in which the HSP distance between two of the three resins becomes the longest (the longest distance between the two resins) must satisfy the relationship in the above equation (1-2-1).

As described above, in the present invention, when there is one combination satisfying the relationship of the above formula (1-2-1), a composition derived from two resins having different compatibility satisfying the relationship undergoes phase separation, and an uneven structure is formed. That is, even when there is a combination of resins that does not satisfy the relationship of the above formula (1-2-1), a desired uneven structure can be obtained.

The total content of the above two or more resins is preferably 50 mass% or more as a nonvolatile component. More preferably, it is 60 mass% or more, and even more preferably, it is 65 mass% or more. When the total content is in this range, the effect of phase separation is sufficiently exerted, and it becomes easy to obtain the desired fine uneven structure. In addition, the total content of the two or more resins is not particularly limited with respect to the upper limit, and it is sufficient as long as it is 100 mass% or less.

In addition, the above two or more types of resins are not particularly limited, but resins exemplified as the “first resin” or “second resin” described below can be cited as preferable ones.

(((First resin)))

From the viewpoint of forming a fine roughening structure by phase separation, the polarity term δp ₁ of the first resin in the above two types of resins is preferably 9.0 MPa ^0.5 or less, more preferably 8.0 MPa ^0.5 or less, and even more preferably 7.0 MPa ^0.5 or less. When the value of the polarity term δp ₁ is in this range, the polarity of the first resin can be lowered, the relationship of the above formula (1-2-1) can be easily satisfied, and as a result, the desired roughening structure can be easily formed. The value of the polarity term δp ₁ is not particularly limited, but is preferably 1.0 MPa ^0.5 or more, more preferably 2.0 MPa ^0.5 or more.

In addition, the hydrogen bond term δh ₁ of the first resin in the above two types of resins is preferably 15.0 MPa ^0.5 or less, more preferably 12.0 MPa ^0.5 or less, even more preferably 9.0 MPa ^0.5 or less, and the dispersion term δd ₁ is not particularly limited, but is preferably 6.0 MPa ^0.5 or more, more preferably 8.0 MPa ^0.5 or more, even more preferably 10.0 MPa ^0.5 or more. When the values of the hydrogen bond term δh ₁ and/or the dispersion term δd ₁ are in these ranges, it becomes easy to satisfy the relationship of the above formula (1-2-1).

In addition, in the present composition, when there are two or more first resins satisfying the relationship of the above formula (1-2-1), at least one first resin may have the value of the above polar term δp ₁ , but all of the first resins may have the value of the above polar term δp ₁ . The same applies to the hydrogen bonding term δh ₁ and the dispersion term δd ₁ .

The content of the first resin satisfying the relationship of the above formula (1-2-1) in the present composition is, as a proportion of the total nonvolatile components in the present composition, preferably 5 to 90 mass%, more preferably 15 to 85 mass%, and even more preferably 35 to 80 mass%. By setting the content to 5 mass% or more, the uneven structure due to phase separation can be sufficiently formed. Furthermore, by setting the content to 90 mass% or less, the content of the other resin can be secured, and the unevenness formation performance due to phase separation can be appropriately adjusted. Furthermore, in the present invention, when there are two or more first resins satisfying the relationship of the above formula (1-2-1), the content means the total content.

From the viewpoint that the polarity term δp ₁ or the hydrogen bonding term δh ₁ is low and that the roughened structure can be effectively formed, it is preferable to use the above-mentioned release agent as the first resin. However, as the first resin, something other than the release agent can also be used, and for example, the above-mentioned crosslinking agent can be used as the first resin. For example, when the above-mentioned binder is used as the second resin in the above-mentioned two types of resins, the crosslinking agent can be used as the first resin for the binder.

(((Second resin)))

From the viewpoint of being able to contribute to the formation of a fine uneven structure by phase separation and also improving the applicability when the composition is used as a coating liquid, the hydrogen bonding term δh ₂ of the second resin in the two types of resins is preferably 8.0 MPa ^0.5 or more, more preferably 10.0 MPa ^0.5 or more, and even more preferably 12.0 MPa ^0.5 or more. When the value of the hydrogen bonding term δh ₂ is in this range, the hydrophilicity of the second resin can be increased, and the applicability can be improved. In addition, it becomes easy to satisfy the relationship (1-2-1) above, and as a result, it becomes easy to form a desired uneven structure.

The hydrogen bonding term δh ₂ of the second resin in the above two types of resins is preferably 25.0 MPa ^0.5 or less, more preferably 23.0 MPa ^0.5 or less, and even more preferably 20.3 MPa ^0.5 or less. By setting the value of the hydrogen bonding term δh ₂ to a certain value or less, the hydrophilicity is not increased too much, thereby preventing the coating film from absorbing water and softening, reducing the roughness strength, and making it easier to improve the slipperiness.

In addition, the polarity term δp ₂ of the second resin in the above two types of resins is preferably 7.0 MPa ^0.5 or more, more preferably 8.0 MPa ^0.5 or more, even more preferably 9.0 MPa ^0.5 or more, and the dispersion term δd ₂ is not particularly limited, but is preferably 6.0 MPa ^0.5 or more, more preferably 8.0 MPa ^0.5 or more, even more preferably 10.0 MPa ^0.5 or more. When the values of the hydrogen bond term δh ₂ and/or the dispersion term δd ₂ are in these ranges, it becomes easy to satisfy the relationship of the above formula (1-2-1).

In addition, in the present composition, when there are two or more second resins satisfying the relationship of the above formula (1-2-1), at least one second resin may have the value of the above hydrogen bonding term δh ₂ , but all of the second resins may have the value of the above hydrogen bonding term δh ₂ . The same applies to the polarity term δp ₂ and the dispersion term δd ₂ .

The content of the second resin satisfying the relationship of the above formula (1-2-1) in the composition is preferably in the range of 10 to 90 mass%, more preferably 15 to 85 mass%, and even more preferably 20 to 65 mass%, as a proportion of the total nonvolatile components in the composition. By setting the content to 10 mass% or more, it is possible to achieve both formation of a roughened structure by phase separation and improvement of the coatability when the composition is used as a coating liquid. In addition, by setting the content to 90 mass% or less, the content of the first resin can be secured, and the performance of forming roughness by phase separation can be appropriately adjusted. In addition, in the present invention, when there are two or more second resins satisfying the relationship of the above formula (1-2-1), the above content means the total content.

The second resin is not particularly limited, but is preferably one having a film-forming ability. More specifically, the second resin may include the aforementioned binder resin or cross-linking agent.

(((Resin of the third component)))

Although the resin layer must contain at least two types of resin, it is preferable to contain three or more types of resin from the viewpoint of making it easier to adjust the uneven shape and also controlling the adhesion to the polyester film and the strength of the coating film. In that case, it is preferable to consider the distance from the resin of the third component in addition to the maximum distance from the two types of resin.

As a more preferable form, it is possible to satisfies the condition that the polarity term δp ₁ of the first resin in the two types of resins is 9.0 MPa ^0.5 or less, and then the two or more types of resins include a resin having an HSP distance of 6.0 or more with respect to the first resin, and do not include a resin having an HSP distance of 5.5 or less. In this case, the HSP distance is calculated by the relational expression defined by the above formula (1-2-1).

In other words, it is desirable that the nearest distance of another resin to the first resin (low δp resin) having a polarity term δp ₁ of 9.0 MPa ^0.5 or less is greater than 5.5, and that the furthest distance of another resin to the low δp resin is 6.0 or more.

The above conditions are preferably satisfied when three or more types of resins are included, but may be satisfied when the resin composition contains only two types of resins.

If the above conditions can be satisfied, the fine rough structure can be expressed more effectively by phase separation. From this point of view, it is more preferable to include a resin having an HSP distance of 7.0 or more, and even more preferably, it includes a resin having an HSP distance of 8.0 or more. In addition, it is more preferable not to include a resin having an HSP distance of 6.0 or less, and even more preferably, it does not include a resin having an HSP distance of 7.0 or less.

It is preferable that the above two or more types of resins contain a release agent as the first resin.

In addition, as a more preferable form, it can be mentioned that the first resin in the above two types of resins is a release agent, and further, the above two or more types of resins include a resin having an HSP distance of 6.0 or more with respect to the release agent, and do not include a resin having an HSP distance of 5.5 or less. In this case, the HSP distance is calculated by the relational expression defined in the above formula (1-2-1).

In other words, it is desirable that the nearest distance of another resin to the heterozygote is greater than 5.5, and the furthest distance of another resin to the heterozygote is greater than 6.0.

If the above conditions can be satisfied, the fine rough structure can be expressed more effectively by phase separation. From this viewpoint, it is more preferable to include a resin having an HSP distance of 7.0 or more for the release agent, and even more preferably, it includes a resin having an HSP distance of 8.0 or more. In addition, it is more preferable not to include a resin having an HSP distance of 6.0 or less for the release agent, and even more preferably, it does not include a resin having an HSP distance of 7.0 or less.

<<<Laminated polyester film with anti-static performance>>>

Polyester films are prone to generating static electricity due to contact friction or peeling during the processing process or use of the product, and in particular, when the surface smoothness is high, the generation of static electricity increases, and dust or small particles easily adhere to it. Therefore, there is a concern about processing defects due to contamination or foreign matter mixing in during the process. In addition, there is also a problem that uneven processing of the secondary processing layer occurs due to film charging during processing. Therefore, for applications where mixing in foreign matter or charging is avoided, a method of applying and laminating an antistatic agent on the surface of a polyester film has been proposed (for example, Japanese Patent Application Laid-Open No. 7-26223).

The same problem exists in the laminated polyester film of the present invention, and a laminated polyester film is desired that can form a fine rough structure even in a thin film, has excellent handleability when winding the film into a roll shape, and can also suppress charging of the film.

Specifically, it is a laminated polyester film having the composition described below.

That is, it is a laminated polyester film comprising a polyester film and a resin layer (hereinafter also referred to as “resin layer (X)”) formed on at least one side of the polyester film by a resin composition (hereinafter also referred to as “resin composition (x)”), and satisfying all of the requirements of (a) to (c) below.

(a) The surface resistance value of the resin layer is 1×10 ¹³ Ω/□ or less.

(b) The resin composition comprises the following compounds (A-a) and (B).

(A-a) Anti-static agent

(B) At least one selected from the group consisting of a binder resin and a crosslinking agent.

(c) The load length ratio (Rmr(80)) of the roughness curve at the 80% cut level of the surface of the resin layer as measured by a scanning probe microscope is 85% or less.

The resin layer (X) in the laminated polyester film is formed of a resin composition (x) as described above, and has a surface resistance value of 1×10 ¹³ Ω/□ or less. In addition, the resin layer (X) has an uneven structure by being formed of a resin composition (x).

The uneven structure of the resin layer (X) is a fine shape formed by phase separation. The uneven structure due to phase separation is that a composition containing resins with different compatibility causes phase separation during processes such as coating, stretching, drying, curing, and heat treatment, thereby forming an uneven structure on the surface. More specifically, the uneven structure is formed on the surface by forming concave or convex portions by phase separation.

Additionally, the structure can be confirmed by various surface analysis methods, such as atomic force microscopy (scanning probe microscopy).

Here, "resin" refers to the main component involved in film formation. More specifically, it includes at least one selected from the group consisting of the above-mentioned compound (A-a) as an antistatic agent and the compound (B) as a binder resin and a crosslinking agent.

The total content of compounds (A-a) and (B) included in the resin composition (x) is preferably 50 mass% or more as a nonvolatile component. More preferably, it is 60 mass% or more, and even more preferably, it is 65 mass% or more. When the total content is in this range, the effect due to phase separation is sufficiently exerted, and it becomes easy to obtain the desired fine uneven structure. In addition, the total content of compounds (A-a) and (B) is not particularly limited with respect to the upper limit, and may be 100 mass% or less.

(((Compound (A-a))))

The resin composition (x) contains an antistatic agent (compound (A-a)). There is no particular limitation on the antistatic agent (A-a), and a conventionally known compound can be used.

As described above, the resin layer (X) has a surface resistance value of 1×10 ¹³ Ω/□ or less, but the surface resistance value can be lowered by the resin composition (x) containing the compound (Aa). In addition, it is presumed that fine unevenness is formed by also containing a specific compound (B) described later for the (Aa) antistatic agent.

Examples of the compound (A-a) include ion-conductive compounds such as ammonium group-containing compounds, polyether compounds, sulfonic acid compounds, and betaine compounds; and π-electron conjugated compounds such as polyacetylene, polyphenylene, polyaniline, polypyrrole, polyisothianaphthene, and polythiophene. Among these, ion-conductive compounds are preferable, and ammonium group-containing compounds are particularly preferable. In the resin composition (x), the antistatic agent may be used singly or in combination of two or more.

In addition, conductive paints containing compounds of a π-electron conjugated system, such as polythiophene or polyaniline, are generally more expensive than conductive paints containing ion-conductive compounds; therefore, from the viewpoint of manufacturing cost, an antistatic agent containing an ion-conductive compound is suitably used.

In addition, from the viewpoint of preventing electrostatic discharge and electrostatic contamination on the opposite side of the film, it is preferable that the antistatic agent be a polymer compound having a number average molecular weight of 1000 or more.

(ammonium group containing compound)

The above ammonium group-containing compound refers to a compound having an ammonium group in the molecule, and is preferably a polymer compound having an ammonium group. For example, a polymer including a monomer having an ammonium group and an unsaturated double bond as components can be used.

Specific examples of such polymers include polymers having repeating units of components represented by the following formula (2-1-1) or the following formula (2-1-2). These may be homopolymers or copolymers, or may be copolymerized with other multiple components. From the viewpoint of being able to efficiently form a roughened structure by compatibility with other materials, or of the antistatic properties of the resulting resin layer (X), polymers having repeating units of components represented by the following formula (2-1-2) are preferred.

In the above formula (2-1-1), R ² is -O- or -NH-, R ³ is an alkylene group, or other structures capable of forming the structure of formula (2-1-1), and R ¹ , R ⁴ , R ⁵ , and R ⁶ are each a hydrogen atom, an alkyl group, a phenyl group, or the like, and these alkyl groups and phenyl groups may be substituted with the groups shown below. The substitutable groups include, for example, a hydroxy group, an amide group, an ester group, an alkoxy group, a phenoxy group, a naphthoxy group, a thioalkoxy group, a thiophenoxy group, a cycloalkyl group, a trialkylammoniumalkyl group, a cyano group, a halogen, and the like.

In the above formula (2-1-2), R ¹ and R ² are each independently a hydrogen atom, an alkyl group, a phenyl group, etc., and these alkyl groups and phenyl groups may be substituted with the groups shown below. The substitutable groups include, for example, a hydroxyl group, an amide group, an ester group, an alkoxy group, a phenoxy group, a naphthoxy group, a thioalkoxy group, a thiophenoxy group, a cycloalkyl group, a trialkylammonium alkyl group, a cyano group, a halogen, etc. In addition, R ¹ and R ² may be chemically bonded, and examples thereof include -(CH ₂ ) _m - (m = an integer from 2 to 5), -CH(CH ₃ )CH(CH ₃ )-, -CH=CH-CH=CH-, -CH=CH-CH=N-, -CH=CH-N=C-, -CH ₂ OCH ₂ -, - (CH ₂ ) ₂ O(CH ₂ ) ₂ -, etc.

A polymer having a component represented by the above formula (2-1-1) or the above formula (2-1-2) as a repeating unit may be copolymerized with other repeating units from the viewpoint of increasing the film-forming properties, increasing the adhesion to a polyester film substrate, and preventing peeling off of the coating film or transfer of components to the back surface.

From the viewpoint of forming a rough structure more effectively, a homopolymer having as repeating units a component represented by the above formula (2-1-1) or the above formula (2-1-2) is preferable.

Other repeating units include, for example, alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, and acrylamides such as n-methylolacrylamide.

X ^- in the above formulas (2-1-1) and (2-1-2) can be appropriately selected within a range that does not impair the gist of the present invention. Examples thereof include halogen ions, sulfonates, phosphates, nitrates, alkyl sulfonates, carboxylates, and the like.

A compound having a component represented by the above formula (2-1-2) or other ammonium bases in the polymer skeleton is preferable because it has excellent heat resistance.

In addition, a polymer in which the components represented by the above formulas (2-1-1) to (2-1-2) and a (meth)acrylate containing polyethylene glycol are copolymerized is preferable because the structure is flexible and, when applied and stretched, a resin layer (X) with excellent uniformity is obtained.

Alternatively, a resin layer (X) with excellent uniformity can be obtained by including a (meth)acrylate polymer containing polyethylene glycol in the coating solution and applying the same.

In addition, the number average molecular weight of the ammonium group-containing compound is usually 1,000 to 500,000, preferably 2,000 to 350,000, more preferably 5,000 to 200,000. By setting the molecular weight to 1,000 or more, the strength of the coating film can be prevented from weakening, and the heat resistance stability can be easily improved. In addition, by setting the molecular weight to 500,000 or less, the viscosity of the coating solution can be prevented from increasing, and the handling property and the application property can be easily improved.

The content of the compound (A-a) in the resin composition (x) is preferably in the range of 5 to 90 mass%, more preferably 10 to 85 mass%, and even more preferably 20 to 75 mass%, as a proportion of the total nonvolatile components in the resin composition (x). By setting the content to 5 mass% or more, not only can a roughened structure be sufficiently formed by phase separation, but also sufficient antistatic performance can be imparted. Furthermore, by setting the content to 90 mass% or less, the content of other resins can be secured, and the performance of forming roughness by phase separation can be appropriately adjusted.

(((Compound (B))))

The resin composition (x) contains, as compound (B), at least one selected from a binder resin and a crosslinking agent.

The above compound (B) can also contribute to the formation of a fine rough structure by phase separation, and can also improve the coatability when the resin composition (x) is used as a coating solution.

((Binder Resin))

The binder resin selected as the compound (B) is defined as a polymer compound having a number average molecular weight (Mn) of 1000 or more as measured by gel permeation chromatography (GPC) in accordance with the “Polymer Compound Safety Evaluation Flow Scheme” (hosted by the Chemical Substances Council, November 1985), and having film-forming properties. In addition, the binder resin excludes the antistatic agent described above and the crosslinking agent described below.

As such a binder resin, there is no particular limitation, and a conventionally known binder resin can be used. For example, a release agent, a (meth)acrylic resin, polyvinyl alcohol, a polyester resin, a polyurethane resin, etc. can be mentioned. Among these, from the viewpoint of easy phase separation with the (A-a) antistatic agent and excellent formation of a fine uneven structure, a release agent is preferable. Furthermore, from the viewpoint of maintaining the unevenness formation performance by phase separation and film formation, a (meth)acrylic resin or polyvinyl alcohol is preferable, and it is more preferable to use at least one of a (meth)acrylic resin and polyvinyl alcohol. That is, the binder resin preferably contains at least one selected from the group consisting of a release agent, a (meth)acrylic resin, and polyvinyl alcohol. In the resin composition (X), the binder resin may be used alone or in combination of two or more.

In addition, the crosslinking agent selected as the compound (B) may be the same as that described for the resin composition described above.

((((especially desirable form))))

As the compounds (A-a) and (B) included in the resin composition (x), a combination of (a) an antistatic agent and a release agent, (b) a binder resin other than an antistatic agent and a release agent, and (c) an antistatic agent, a release agent, and a crosslinking agent is particularly preferable, and the combination of (c) is particularly preferable.

In the case of the combination of the above (c), the content of each component is preferably such that when the content of the antistatic agent as compound (A-a) is 100 parts by mass, the ratio (antistatic agent/release agent/crosslinking agent) of compound (B) is 100/(10 to 500)/(10 to 500), and more preferably 100/(20 to 300)/(20 to 250).

<<<Properties of laminated polyester film with anti-static performance>>>

The load length ratio (Rmr(80)) of the roughness curve at a cut level of 80% of the surface of the resin layer of a laminated polyester film having antistatic performance is 85% or less.

The load length ratio (Rmr(c)) is one of the line roughness parameters (JIS B 0601), and represents the ratio of the load length ML(c) of the contour curve element at the cutting level c (height% or ㎛) to the evaluation length Ln, and is obtained from the following equation (2-1-3).

Here, the inventors of the present invention considered that the load length ratio (Rmr(80)) is effective as an index representing the uneven distribution of the uneven structure. For example, when the concave distribution is large, the load length ratio (Rmr(80)) value becomes small, and when the convex distribution is large, the load length ratio (Rmr(80)) value becomes large. When the load length ratio (Rmr(80)) is small, the gap between films when the film is wound into a roll shape becomes large, the easiness of air escape is improved, and the winding property, etc. can be improved.

The load length ratio (Rmr(80)) of the roughness curve at the cutting level of 80% is, as described above, 85% or less, preferably 70% or less, more preferably 58% or less, and particularly preferably 50% or less. The lower limit is not particularly limited and is about 1%, preferably 4%, and more preferably 6%.

The above load length ratio (Rmr(80)) can be adjusted by the composition or content of the resin composition (X).

In addition, the load length ratio (Rmr(50)) of the roughness curve at the cutting level of 50% of the resin layer surface is preferably 60% or less, more preferably 40% or less, and even more preferably 25% or less. The lower limit is not particularly limited and is about 1%, preferably 3%, and more preferably 5%.

Here, the inventors of the present invention thought that considering the load length ratio (Rmr(50)) in addition to the load length ratio (Rmr(80)) is more effective as an index representing the uneven distribution of the uneven structure. For example, even in the case of the same load length ratio (Rmr(80)) value, when the load length ratio (Rmr(50)) value is small, the convex shape is thin, and when the load length ratio (Rmr(50)) value is large, the convex shape is thick. Therefore, when the load length ratio (Rmr(50)) is small, the uneven shape becomes finer, and when the film is wound into a roll, the gap created between the films becomes larger, so that the easiness of air escape is improved, and the winding property, etc. can be improved.

The above load length ratio (Rmr(50)) can also be adjusted by the composition or content of the resin composition (X).

In addition, the arithmetic mean roughness (Ra) of the surface of the resin layer is preferably 10 nm or more, more preferably 15 nm or more, and even more preferably 20 nm or more. The upper limit is not particularly limited, but is preferably 600 nm, more preferably 400 nm, and even more preferably 200 nm. When the arithmetic mean roughness (Ra) is 10 nm or more, it can be said that the resin layer (X) has a fine uneven structure, and the handleability of the laminated polyester film becomes good. In addition, when the arithmetic mean roughness (Ra) is 600 nm or less, it can be said that the uneven structure of the resin layer (X) has a sufficiently fine shape.

Arithmetic mean roughness (Ra) is one of the linear roughness parameters (JIS B 0601) and represents the average value of the average elevation difference in the mean plane.

That is, when a portion of the standard length L is extracted, and the average line of this extracted portion is represented as the x-axis and the direction of the vertical magnification is represented as the y-axis to form a roughness curve as y = Z(x), it is obtained from the following equation (2-1-4).

In addition, the ten-point average roughness (Rzjis) of the surface of the resin layer is preferably 28 nm or more, more preferably 40 nm or more, further preferably 60 nm or more, and particularly preferably 120 nm or more. The upper limit is not particularly limited, but is preferably 800 nm, more preferably 600 nm, and further preferably 500 nm. When the ten-point average roughness (Rzjis) is 28 nm or more, it can be said that the resin layer (X) has a sufficient uneven structure. In addition, when the ten-point average roughness (Rzjis) is 800 nm or less, it can be said that the uneven structure of the resin layer (X) is a sufficiently fine shape.

The ten-point average roughness (Rzjis) is one of the line roughness parameters (JIS B 0601), and represents the sum of the average of the fifth from the maximum peak height (Zp) of the contour curve and the average of the fifth from the deepest valley depth (Zv) in the reference length L, and is obtained from the following equation (2-1-5).

The above arithmetic mean roughness (Ra) and ten-point average roughness (Rzjis) can be adjusted by the composition or content of the resin composition (X).

In addition, the load length ratio (Rmr(80)), load length ratio (Rmr(50)), arithmetic mean roughness (Ra) and ten-point average roughness (Rzjis) of the resin layer surface are measured by the method described in the examples using an atomic force microscope (scanning probe microscope). If the measurement is by an atomic force microscope (scanning probe microscope), it is possible to grasp a finer structure of the surface, and it becomes possible to obtain a numerical value that strongly reflects the effect by the resin layer (X).

In a laminated polyester film having antistatic performance, the surface resistance value of the surface of the resin layer is 1×10 ¹³ Ω/□ or less, preferably 5×10 ¹¹ Ω/□ or less, more preferably 5×10 ¹⁰ Ω/□ or less. In addition, there is no particular limitation on the lower limit of the surface resistance value, but considering the cost required for manufacturing the laminated polyester film, it is preferably 1×10 ⁴ Ω/□ or more.

When the roll in which the laminated polyester film is wound is re-wound for secondary processing, peeling charging occurs when the resin layer and the opposite surface are peeled off. In addition, charging occurs between the roll, the resin layer, and the opposite surface when the film is returned to the roll. Since the charging that occurs leads to adhesion of foreign substances or uneven processing in the secondary processing layer, it is important to prevent charging by lowering the surface resistance value or to speed up the attenuation.

When the surface resistance value is within this range, it becomes possible to maintain low charge on the film surface, and to suppress adhesion of foreign substances to the laminated polyester film or influence on the secondary processing layer.

The above surface resistance value can be adjusted by the type or content of the antistatic agent compound (A-a) in the resin composition (x), the type of compound (B) to be combined, the amount of the nonvolatile component applied to the resin layer (X), etc.

A laminated polyester film having antistatic properties can be used for various purposes to improve handling properties while suppressing static electricity on the film surface, and its uses are not particularly limited.

Additionally, the surface resistance value can be measured by the method described below.

(Method of measuring surface resistance value)

It can be measured using a high-resistance resistivity meter (Hiresta UX MCP-HT800, manufactured by Mitsubishi Chemical Analytech Co., Ltd.) and a measurement probe (UR-100). As measurement conditions, for example, in a measurement atmosphere of 23°C and 50%RH, after sufficiently humidifying a laminated polyester film (sample), the surface resistance value (Ω/□) of the resin layer after 1 minute at an applied voltage of 100 V can be measured.

<<<Other aspects of laminated polyester film having anti-static properties>>>

There are other aspects of laminated polyester films having antistatic properties. Specifically,

A laminated polyester film comprising a polyester film and a resin layer formed by a resin composition on at least one side of the polyester film,

The surface resistance value of the above resin layer is 1×10 ¹³ Ω/□ or less,

The above resin composition comprises two or more types of resins,

A laminated polyester film in which at least two types of resins among the above two or more types of resins, one of which is a first resin and the other is a second resin, satisfy the relationship of the following formula (2-2-1).

HSP distance={4×(δd ₁ -δd ₂ ) ² +(δp ₁ -δp ₂ ) ² +(δh ₁ -δh ₂ ) ² } ^0.5 ≥5.0 … (2-2-1)

(Wherein, δd ₁ , δp ₁ and δh ₁ represent δd, δp and δh of the first resin, respectively, in the Hansen solubility parameters [δd, δp, δh], and δd ₂ , δp ₂ and δh ₂ represent δd, δp and δh of the second resin, respectively. In addition, δh ₁ ≥ δh ₂ .)

In addition, with respect to the HSP distance, as described above, in the present embodiment, with respect to the first resin and the second resin, the resin having a larger value of the hydrogen bond term δh is designated as the first resin, and the resin having a smaller value of the hydrogen bond term δh is designated as the second resin. That is, δh ₁ ≥ δh ₂ . However, when the values of the hydrogen bond term δh of the two resins are the same, the resin having a larger value of the polar term δp is designated as the first resin, and when the values of the polar terms δp are also the same, the resin having a smaller value of the dispersion term δd is designated as the first resin.

By taking this aspect, a laminated polyester film is provided which can form a fine rough structure even in a thin film and can suppress charging of the film.

In the above aspect, the surface resistance value of the resin layer surface of the laminated polyester film is 1×10 ¹³ Ω/□ or less, preferably 5×10 ¹¹ Ω/□ or less, more preferably 5×10 ¹⁰ Ω/□ or less. In addition, there is no particular limitation on the lower limit of the surface resistance value, but considering the cost required for manufacturing the laminated polyester film, it is preferably 1×10 ⁴ Ω/□ or more.

When the surface resistance value is within this range, it becomes possible to maintain low charge on the film surface, and to suppress adhesion of foreign substances to the laminated polyester film or influence on the secondary processing layer.

(((First resin)))

From the viewpoint of contributing to the formation of a fine roughening structure by phase separation and imparting antistatic properties, the hydrogen bonding term δh ₁ of the first resin in the above two types of resins is preferably 8.0 MPa ^0.5 or more, more preferably 13.0 MPa ^0.5 or more, and even more preferably 16.0 MPa ^0.5 or more. When the value of the hydrogen bonding term δh ₁ is in this range, the hydrophilicity of the first resin can be enhanced, the relationship of the above formula (2-2-1) can be easily satisfied, and as a result, the desired roughening structure can be easily formed. In addition, antistatic performance can also be easily imparted from the height of the hydrophilicity. The upper limit of the hydrogen bonding term δh ₁ is not particularly limited, but is preferably 25.0 MPa ^0.5 or less, more preferably 23.0 MPa ^0.5 or less.

In addition, the polarity term δp ₁ of the first resin in the above two types of resins is preferably 4.0 MPa ^0.5 or more, more preferably 7.0 MPa ^0.5 or more, and even more preferably 10.0 MPa ^0.5 or more, and the dispersion term δd ₁ is not particularly limited, but is preferably 6.0 MPa ^0.5 or more, more preferably 8.0 MPa ^0.5 or more, and even more preferably 10.0 MPa ^0.5 or more. When the values of the polarity term δp ₁ and/or the dispersion term δd ₁ are in these ranges, it becomes easy to satisfy the relationship of the above formula (2-2-1).

In addition, in the resin composition (X), when there are two or more first resins satisfying the relationship of the above formula (2-2-1), at least one first resin may have the value of the above-mentioned hydrogen bonding term δh ₁ , but all of the first resins may have the value of the above-mentioned hydrogen bonding term δh ₁ . The same applies to the polarity term δp ₁ and the dispersion term δd ₁ .

The content of the first resin satisfying the relationship of the above formula (2-2-1) in the resin composition (x) is preferably in the range of 5 to 90 mass%, more preferably 10 to 85 mass%, and even more preferably 20 to 75 mass%, as a proportion of the total nonvolatile components in the resin composition (x). By setting the content to 5 mass% or more, not only can the uneven structure by phase separation be sufficiently formed, but also sufficient antistatic performance can be imparted. Furthermore, by setting the content to 90 mass% or less, the content of the other resin can be secured, and the unevenness formation performance by phase separation can be appropriately adjusted. Furthermore, in a case where there are two or more first resins satisfying the relationship of the above formula (2-2-1), the content means the total content.

From the viewpoints that the hydrogen bonding term δh ₁ or the polarity term δp ₁ is high and that an uneven structure can be effectively formed and that antistatic properties can be imparted, it is preferable to use an antistatic agent described later as the first resin. However, other than an antistatic agent, the first resin can also be used, and for example, a binder or a crosslinking agent described later can be used as the first resin.

(((Second resin)))

From the viewpoint of contributing to the formation of a fine uneven structure by phase separation, the hydrogen bond term δh ₂ of the second resin in the above two types of resins is preferably 14.0 MPa ^0.5 or less, more preferably 10.0 MPa ^0.5 or less, and even more preferably 8.0 MPa ^0.5 or less. When the value of the hydrogen bond term δh ₂ is in this range, the hydrophilicity of the second resin can be lowered, the relationship (2-2-1) above can be easily satisfied, and as a result, the desired uneven structure can be easily formed.

In the above two types of resins, the hydrogen bonding term _δh2 of the second resin is preferably 1.0 MPa ^0.5 or more, more preferably 2.0 MPa ^0.5 or more, and still more preferably 3.0 MPa ^0.5 or more.

In addition, the polarity term δp ₂ of the second resin in the above two types of resins is preferably 16.0 MPa ^0.5 or less, more preferably 10.0 MPa ^0.5 or less, even more preferably 7.0 MPa ^0.5 or less, and the dispersion term δd ₂ is not particularly limited, but is preferably 6.0 MPa ^0.5 or more, more preferably 8.0 MPa ^0.5 or more, even more preferably 10.0 MPa ^0.5 or more. When the values of the polarity term δp ₂ and/or the dispersion term δd ₂ are in these ranges, it becomes easy to satisfy the relationship of the above formula (2-2-1).

In addition, in the resin composition (x), when there are two or more second resins satisfying the relationship of the above formula (2-2-1), at least one second resin may have the value of the above-mentioned hydrogen bond term δh ₂ , but all of the second resins may have the value of the above-mentioned hydrogen bond term δh ₂ . The same applies to the polar term δp ₂ and the dispersion term δd ₂ .

The content of the second resin satisfying the relationship of the above formula (2-2-1) in the resin composition (x) is preferably in the range of 10 to 95 mass%, more preferably 15 to 90 mass%, and even more preferably 20 to 80 mass%, as a proportion of the total nonvolatile components in the resin composition (x). By setting the content to 10 mass% or more, it can contribute to the formation of an uneven structure by phase separation. Furthermore, by setting the content to 95 mass% or less, the content of the first resin can be secured, a desired surface resistance value can be obtained, and the unevenness formation performance by phase separation can be appropriately adjusted. Furthermore, in a case where there are two or more second resins satisfying the relationship of the above formula (2-2-1), the above content means the total content.

The second resin is not particularly limited, but from the viewpoint that it can effectively form a rough structure, a release agent is preferable. In addition, from the viewpoint that it has a film-forming ability, a binder resin or a crosslinking agent is preferable. More specifically, as the second resin, a release agent, a binder resin, a crosslinking agent, etc. described below can be mentioned.

(((Resin of the third component)))

The resin layer (X) must contain at least two types of resins, but from the viewpoint of making it easier to adjust the uneven shape and also being able to control the adhesion to the polyester film and the strength of the coating film, it is preferable to contain three or more types of resins. In that case, in addition to the maximum distance between the two types of resins, it is also preferable to consider the distance from the resin of the third component.

In a preferred form, when three or more types of resins are included, it is preferable that the two or more types of resins do not include a resin having an HSP distance of 3.0 or less, and it is more preferable that the two or more types of resins do not include a resin having an HSP distance of 4.0 or less. In this case, the HSP distance is calculated by the relational expression defined by the above formula (2-2-1).

If the above conditions can be satisfied, the fine rough structure can be expressed more effectively by phase separation, so that the air leakage index can be made good as a result, and when the laminated polyester film is rolled up, the air that has been rolled up can be easily escaped, and it becomes possible to prevent defects in the roll appearance, such as wrinkles or unevenness of the end faces. In addition, the air leakage index will be explained in detail later.

The above surface resistance value can be adjusted by the type or content of the antistatic agent in the resin composition (x), the HSP distance with respect to other resins to be combined, the amount of nonvolatile component applied to the resin layer (X), etc.

<<<Lee Hyung Film>>>

The laminated polyester film of the present invention may be a release film having a release layer on the side opposite to the resin layer of the polyester film. The specific configuration is as follows.

A release film comprising a polyester film, a resin layer formed by a resin composition on one surface of the polyester film, and a release layer on the other surface of the polyester film, and satisfying both of the following requirements (1) and (2).

(1) The resin composition comprises the following compounds (A) and (B).

(A) Low polarity compound

(B) At least one selected from the group consisting of a binder resin and a crosslinking agent.

(2) The load length ratio (Rmr(80)) of the roughness curve at the cutting level of 80% of the surface of the resin layer as measured by a scanning probe microscope is 94% or less.

As a laminated configuration of the release film, as described above, it includes a configuration having a release layer, a polyester film, and a resin layer in that order.

Additionally, the release layer may be formed directly on the polyester film, but another layer may be provided between the polyester film and the release layer.

Additionally, the resin layer may be formed directly on the polyester film, but another layer may be provided between the polyester film and the resin layer.

<<Heterogeneity layer>>

A release film is one that has a release layer on the other surface side of a polyester film.

The above-mentioned heteromorphic layer is laminated directly on the polyester film or by interposing another layer, as described above. As the other layer, in addition to an adhesive-friendly coating layer for improving adhesion to the polyester film, an antistatic layer or an anti-blocking layer may be mentioned.

<Brother Composition>

The above heterogeneous layer is formed from a heterogeneous composition.

Additionally, the dissociative composition contains a dissociative agent.

(((Lee Brother)))

As the above release agent, there is no particular limitation, and conventionally known release agents can be used. For example, silicone compounds, long-chain alkyl group-containing compounds, waxes, fluorine compounds, etc. are exemplified. Among them, at least one of a silicone compound and a long-chain alkyl group-containing compound is preferable. In the release agent composition, the release agent may be used alone, or two or more may be used in combination.

((silicon compound))

A silicone compound is a compound having a silicone structure in its molecule, or in other words, a compound having a main skeleton by siloxane bonds. Examples of the silicone compound or the main skeleton constituting the silicone compound include organopolysiloxane such as polydimethylsiloxane, acrylic graft silicone, silicone graft acrylic, amino-modified silicone, perfluoroalkyl-modified silicone, and alkyl-modified silicone. Among these, from the viewpoint of excellent releasability, organopolysiloxane such as polydimethylsiloxane is preferable.

Among these, a silicone compound having a functional group capable of reacting with a (meth)acryloyl group among the compounds containing a (meth)acryloyl group described below is preferable, and among these, a silicone compound containing a Si-H group is particularly preferable. The Si-H group of the silicone compound has a property of increasing adhesion to the present polyester film. Among these, from the viewpoint of forming a crosslinked structure having a skeleton derived from a silicone compound in the release layer, a silicone compound having a Si-H group and an alkenyl group is preferable.

The molecular weight of the silicone compound is not particularly limited. Among them, from the viewpoint of adhesion between the polyester film and the release layer, the number average molecular weight is preferably 5,000 or more, and more preferably 10,000 or more. The upper limit is not particularly limited, but is usually 1,000,000 or less.

The number average molecular weight of a silicone compound can be measured, for example, by gel permeation chromatography (GPC) and calculated as a polystyrene equivalent.

Among the above, as a silicone compound used in the release agent composition, it is preferable to contain a curable silicone compound, taking heat resistance and contamination resistance into consideration.

As for the type of curable silicone compound, it can be used in any curing reaction type such as addition curing, condensation curing, ultraviolet curing, or electron beam curing. Among them, addition curing silicone compounds are more preferable from the viewpoint of being able to increase the cohesiveness of the coating film.

An addition-curable silicone compound is a silicone compound having an unsaturated hydrocarbon group and a hydrogen group as functional groups in its structure, and an addition-curing reaction is performed by a reaction of these functional groups. That is, it is a mixture of a silicone compound having a Si-H group and a silicone compound containing an alkenyl group, or a silicone compound containing a Si-H group and a vinyl group in the molecule.

It is preferable from the viewpoint of availability that the unsaturated hydrocarbon group and the hydrogen group do not exist in the same molecule, and it is preferable to include the functional group in a separate silicone molecule and use a mixture of them. Therefore, it is preferable to use a silicone compound having an unsaturated hydrocarbon group as a functional group and a silicone compound having a hydrogen group as a functional group in combination.

As the silicone compound having an unsaturated hydrocarbon group as a functional group, an example thereof is polydimethylsiloxane containing an unsaturated hydrocarbon group.

The unsaturated hydrocarbon group must contain at least two in the polydimethylsiloxane molecule. As the unsaturated hydrocarbon group, an alkenyl group having 2 to 8 carbon atoms, such as a vinyl group, a propenyl group, a butenyl group, and a pentenyl group, can be mentioned. Among these, a vinyl group is preferable due to ease of industrial availability.

The alkenyl group containing at least two carbon atoms may contain alkenyl groups having different carbon numbers.

Polydimethylsiloxane containing an unsaturated hydrocarbon group has an alkenyl group and a methyl group as functional groups directly bonded to a silicon atom, and may also have various other functional groups. Examples of functional groups other than a methyl group include alkyl groups such as an ethyl group, a propyl group, and a butyl group, cycloalkyl groups such as a cyclohexyl group, aryl groups such as a phenyl group and a methylphenyl group, and alkoxy groups such as a hydroxy group, a methoxy group, and an ethoxy group. From the viewpoint of adhesion to a polyester film, it is preferable to include a phenyl group or a methoxy group.

Meanwhile, as the silicone compound having a hydrogen group as a functional group, a polydimethylsiloxane containing a hydrogen group can be mentioned. A polydimethylsiloxane containing a hydrogen group is a polydimethylsiloxane having a hydrogen atom bonded to a silicon atom. It is necessary to contain at least two hydrogen atoms bonded to silicon atoms in one molecule, and from the viewpoint of curing characteristics, it is preferable to contain three or more. The hydrogen atom bonded to silicon may be a terminal of a polydimethylsiloxane molecular chain or a side chain.

Polydimethylsiloxane containing hydrogen groups has hydrogen groups and methyl groups as functional groups directly bonded to silicon atoms, but may also have various other functional groups. Examples of functional groups other than methyl groups include alkyl groups such as ethyl, propyl, and butyl groups, cycloalkyl groups such as cyclohexyl groups, aryl groups such as phenyl and methylphenyl groups, hydroxy groups, and alkoxy groups such as methoxy and ethoxy groups.

The polydimethylsiloxane skeleton containing an unsaturated hydrocarbon group and the polydimethylsiloxane skeleton containing a hydrogen group may each be linear or branched.

The blending of unsaturated hydrocarbon-containing polydimethylsiloxane and hydrogen group-containing polydimethylsiloxane is preferably such that the molar ratio of the total Si-H groups to the total alkenyl groups (amount of Si-H groups/amount of alkenyl groups) is 1.0 to 5.0.

If the molar ratio is 1.0 or more, curability can be maintained, and if it is 5.0 or less, the amount of remaining Si-H groups is not too much, and the peeling force for the adhesive does not become too heavy, which is preferable.

From this point of view, it is preferable that it be between 1.0 and 5.0, and among them, it is particularly preferable that it be between 1.6 and 4.8, and among them, it is particularly preferable that it be between 2.0 and 4.6.

The silicone compound used in the release agent composition may be a solvent-based curable silicone or a solventless curable silicone. It is also possible to use a mixture of solvent-based curable silicone and solventless curable silicone.

In addition, in both solvent-curable silicone and non-solvent-curable silicone, it is preferable that the curable silicone has a releasable property and that it includes an addition reaction of a vinyl group and a group having a silicon-hydrogen bond during the curing process (so-called addition-type silicone).

From the viewpoint of safety in terms of working environment, organic solvent explosion, fire, etc., it is preferable to use the aforementioned silicone compound as a silicone emulsion.

When emulsifying a silicone compound, a surfactant component can be used as an emulsion stabilizer.

Surfactants include nonionic surfactants and anionic surfactants.

Examples of nonionic surfactants include polyoxyalkylene alkyl ethers such as polyoxyethylene alkyl ethers, polyoxyalkylene phenyl ethers such as polyoxyethylene phenyl ethers, glycerin alkyl ethers, glycerin fatty acid esters and alkylene glycol adducts thereof, polyglycerin fatty acid esters and alkylene glycol adducts thereof, propylene glycol fatty acid esters and alkylene glycol adducts thereof, and polyalkylene glycol fatty acid esters.

Examples of the anionic surfactant include fatty acid soaps such as sodium stearate or triethanolamine palmitate, alkyl ether carboxylic acids and their salts, alkyl sulfonic acids, alkenyl sulfonates, sulfonates of fatty acid esters, alkyl sulfate ester salts, secondary higher alcohol sulfate ester salts, alkyl and allyl ether sulfate ester salts, fatty acid ester sulfate ester salts, polyoxyethylene alkyl sulfate ester salts, sulfate ester salts such as lotus oil, alkyl phosphates, ether phosphates, alkyl allyl ether phosphates, amide phosphates, and the like. Of these, nonionic surfactants are preferable, and from the viewpoint of the stability of the silicone emulsion, polyoxyalkylene alkyl ethers and polyoxyalkylene phenyl ethers are more preferable.

As the polyoxyalkylene alkyl ether, examples thereof include polyoxyethylene alkyl ether, polyoxypropylene alkyl ether, and polyoxybutylene alkyl ether. Among these, polyoxyethylene alkyl ether is preferable. In addition, the alkyl group is preferably a straight-chain or branched alkyl group having 8 to 30 carbon atoms, and is more preferably a straight-chain or branched alkyl group having 8 to 16 carbon atoms.

As polyoxyalkylene phenyl ethers, polyoxyethylene phenyl ether, polyoxypropylene phenyl ether, polyoxybutylene phenyl ether, etc. can be mentioned. Among these, polyoxyethylene phenyl ether is preferable. In addition, the phenyl group is an unsubstituted or substituted phenyl group, and it is preferable that it is a styrenated phenyl group in which the hydrogen atom of the phenyl group is substituted with a styryl group.

((Long-chain alkyl group-containing compound))

A long-chain alkyl group-containing compound is a compound having a straight-chain or branched alkyl group having 6 or more carbon atoms, preferably 8 or more, more preferably 12 or more.

As the alkyl group, examples thereof include alkyl groups having 6 to 30 carbon atoms, such as a hexyl group, an octyl group, a decyl group, a lauryl group, an octadecyl group, and a behenyl group. Examples of the compound having an alkyl group include various long-chain alkyl group-containing polymer compounds, long-chain alkyl group-containing amine compounds, long-chain alkyl group-containing ether compounds, and long-chain alkyl group-containing quaternary ammonium salts. Considering heat resistance and contamination resistance, a polymer compound is preferable. Furthermore, from the viewpoint of effectively obtaining releasability, a polymer compound having a long-chain alkyl group in a side chain is more preferable.

A polymer compound having a long-chain alkyl group in the side chain can be obtained by reacting a polymer having a reactive group with a compound having an alkyl group capable of reacting with the reactive group. Examples of the reactive group include a hydroxyl group, an amino group, a carboxyl group, an acid anhydride, and the like. Examples of the compound having these reactive groups include polyvinyl alcohol, polyethyleneimine, polyethyleneamine, a polyester resin containing a reactive group, a poly(meth)acrylic resin containing a reactive group, and the like. Among these, polyvinyl alcohol is preferable in consideration of releasability and ease of handling. The degree of polymerization of the polyvinyl alcohol used is not particularly limited, but is usually 100 or more, preferably 300 to 40,000. In addition, the degree of saponification of polyvinyl alcohol is not particularly limited, but is usually 70 mol% or more, preferably 70 to 99.9 mol%, more preferably 80 to 97 mol%, and even more preferably 86 to 95 mol%.

Examples of the compound having an alkyl group capable of reacting with the above reactive group include long-chain alkyl group-containing isocyanates such as hexyl isocyanate, octyl isocyanate, decyl isocyanate, lauryl isocyanate, octadecyl isocyanate, and behenyl isocyanate; long-chain alkyl group-containing acid chlorides such as hexanoyl chloride, octanoyl chloride, decanoyl chloride, lauroyl chloride, octadecanoyl chloride, and behenoyl chloride; long-chain alkyl group-containing amines; and long-chain alkyl group-containing alcohols. Among these, considering ease of handling, long-chain alkyl group-containing isocyanates are preferable, and octadecyl isocyanate is particularly preferable.

In addition, a polymer compound having a long-chain alkyl group in the side chain can also be obtained by polymerization of a long-chain alkyl (meth)acrylate or copolymerization of a long-chain alkyl (meth)acrylate with another vinyl group-containing monomer. Examples of the long-chain alkyl (meth)acrylate include hexyl (meth)acrylate, octyl (meth)acrylate, decyl (meth)acrylate, lauryl (meth)acrylate, octadecyl (meth)acrylate, and behenyl (meth)acrylate.

When a silicone compound is used as the above-mentioned release agent, the content of the silicone compound in the release agent composition is, as a proportion of the total nonvolatile components in the release agent composition, preferably 50 to 100 mass%, more preferably 70 to 100 mass%, even more preferably 90 to 99 mass%, and particularly preferably 95 to 99 mass%. It is preferable that the silicone compound is contained in the release layer in an amount of 50 mass% or more, because sufficient release properties are obtained. In addition, by setting the content to 99 mass% or less, a compound containing a (meth)acryloyl group described later can be included, so that the adhesion to the present polyester film can be further enhanced.

When a release agent other than a silicone compound (for example, a long-chain alkyl group-containing compound, a wax, a fluorine compound, etc.) is used as the release agent, the content of the release agent other than the silicone compound in the release agent composition is preferably in the range of 10 to 90 mass%, more preferably 20 to 80 mass%, even more preferably 30 to 70 mass%, and particularly preferably 50 to 70 mass%, as a proportion of the total nonvolatile components in the release agent composition. By setting the content to 10 mass% or more, the release property becomes good. In addition, by setting the content to 90 mass% or less, sufficient solvent resistance can be obtained.

(((crosslinker)))

The release agent composition preferably contains a crosslinking agent when a release agent other than a silicone compound is used as the release agent. There is no particular limitation on the crosslinking agent, and any crosslinking agent known in the art can be used. By using a crosslinking agent, the strength of the release layer can be increased, and the layer can be made difficult for deposition of the release component.

As the crosslinking agent, examples thereof include melamine compounds, oxazoline compounds, epoxy compounds, carbodiimide compounds, isocyanate compounds, and silane coupling compounds. Among these, from the viewpoint of enhancing the strength of the release layer and improving adhesion to the polyester film, it is preferable that the crosslinking agent includes a melamine compound. In the release agent composition, the crosslinking agent may be used alone or in combination of two or more.

In addition, the specific aspects and preferred aspects of the crosslinking agent that can be contained in the release agent composition are the same as those of the crosslinking agent that can be contained in the above-described resin composition, and thus, all of them can be cited. That is, the crosslinking agent exemplified in the release agent composition is the same as that exemplified in the above-described resin composition.

When the release agent composition contains a crosslinking agent, the content of the crosslinking agent in the release agent composition is, as a proportion of the total nonvolatile components in the release agent composition, preferably 10 to 90 mass%, more preferably 20 to 80 mass%, even more preferably 30 to 70 mass%, and particularly preferably 30 to 50 mass%. By setting the content to 10 mass% or more, the strength of the release layer can be improved. In addition, by setting the content to 90 mass% or less, sufficient release property can be secured.

((((meth)acryloyl group containing compound)))

The release agent composition may further contain a compound containing a (meth)acryloyl group when a silicone compound is used as the release agent. By containing a compound containing a (meth)acryloyl group, the adhesion to the polyester film can be further enhanced.

As the compound containing the above (meth)acryloyl group, there may be a polymer (meth)acrylate compound or a monomer (meth)acrylate compound, and either may be used. Furthermore, these may be used in combination. Here, the polymer (meth)acrylate compound means a macromonomer.

As the (meth)acrylate compound, examples thereof include urethane (meth)acrylate compounds, epoxy (meth)acrylate compounds, polyester (meth)acrylate compounds, polyalkylene (meth)acrylate compounds, and other (meth)acrylate compounds. Among these, as the compound containing a (meth)acryloyl group, a mixture including a combination of urethane (meth)acrylate or urethane (meth)acrylate and a (meth)acrylate compound other than urethane (meth)acrylate is preferable.

As the urethane (meth)acrylate compound, a conventionally known compound can be used, and is not particularly limited, but examples thereof include a compound obtained by a reaction between a (meth)acrylate compound having a hydroxyl group and an isocyanate compound, a compound obtained by a reaction between a (meth)acrylate compound having a hydroxyl group, a polyol, and an isocyanate compound, and the like. The urethane (meth)acrylate compound may be a polymer or a monomer, but from the viewpoint of adhesion to a polyester film, a polymer is preferable.

As (meth)acrylate compounds having a hydroxyl group, for example, 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, glycerin mono(meth)acrylate, glycerin di(meth)acrylate, diglycerin mono(meth)acrylate, diglycerin tri(meth)acrylate, trimethylolpropane di(meth)acrylate, pentaerythritol mono(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol di(meth)acrylate, dipentaerythritol tri(meth)acrylate, dipentaerythritol tetra(meth)acrylate, Dipentaerythritol penta(meth)acrylate, sorbitol di(meth)acrylate, sorbitol tri(meth)acrylate, sorbitol tetra(meth)acrylate, sorbitol penta(meth)acrylate, sorbitol mono(meth)acrylate diglycerin di(meth)acrylate, an adduct of glycidyl(meth)acrylate and (meth)acrylic acid, a reaction product of two molecules of (meth)acrylic acid and one molecule of 1,6-hexanediol diglycidyl, a reaction product of two molecules of epoxy(meth)acrylic acid and one molecule of neopentylglycol diglycidyl, a reaction product of two molecules of (meth)acrylic acid and one molecule of bisphenol A diglycidyl, a reaction product of two molecules of (meth)acrylic acid and a diglycidyl form of a propylene oxide adduct of bisphenol A, two molecules of Examples thereof include reaction products of (meth)acrylic acid and polyol diglycidyl, such as a reaction product of (meth)acrylic acid and one molecule of diglycidyl phthalate, a reaction product of two molecules of (meth)acrylic acid and one molecule of polyethylene glycol diglycidyl, and a reaction product of two molecules of (meth)acrylic acid and one molecule of polypropylene glycol diglycidyl. These may be used alone or in combination of two or more.

Among these, from the viewpoint of more effectively improving the adhesion between the silicone compound and the polyester film, it is preferable that the number of (meth)acryloyl groups in one molecule of diglycerin tri(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, sorbitol tri(meth)acrylate, sorbitol tetra(meth)acrylate, sorbitol penta(meth)acrylate, etc. is 3 or more, and it is more preferable that the number of (meth)acryloyl groups in one molecule of dipentaerythritol penta(meth)acrylate, sorbitol penta(meth)acrylate, etc. is 5 or more.

An isocyanate compound is a compound having an isocyanate derivative structure, represented by isocyanate or blocked isocyanate. As the isocyanate, for example, aromatic isocyanates such as tolylene diisocyanate, xylylene diisocyanate, methylene diphenyl diisocyanate, phenylene diisocyanate, and naphthalene diisocyanate; aliphatic isocyanates having an aromatic ring such as α,α,α',α'-tetramethylxylylene diisocyanate; aliphatic isocyanates such as methylene diisocyanate, ethylene diisocyanate, propylene diisocyanate, lysine diisocyanate, trimethylhexamethylene diisocyanate, and hexamethylene diisocyanate; cyclohexane diisocyanate, dicyclohexylmethane diisocyanate, methylcyclohexane diisocyanate, isophorone diisocyanate, hydrogenated xylylene diisocyanate, and methylene bis(4-cyclohexyl isocyanate). Alicyclic isocyanates such as isopropylidene dicyclohexyl diisocyanate can be exemplified. These isocyanates may also be reacted with various polymers or compounds. In addition, polymers or derivatives such as biuretized compounds, isocyanurated compounds, uretdione compounds, and carbodiimide-modified compounds of these isocyanates can also be exemplified. These may be used alone or in combination of two or more. Among the above isocyanates, from the viewpoint of improving the adhesion of the release layer to the polyester film, aliphatic isocyanates or alicyclic isocyanates are preferable, and alicyclic isocyanates are more preferable.

Examples of polyols include polycarbonate polyol, polyester polyol, and polyether polyol, and either high molecular weight polyol or low molecular weight polyol can be used.

The high molecular weight polyol is not particularly limited, but is preferably one having a number average molecular weight of 400 to 8,000, more preferably one having a number average molecular weight of 400 to 4,000. When the number average molecular weight is within this range, it is possible to obtain an appropriate viscosity and a good appearance of the release layer.

Examples of high molecular weight polyols include polycarbonate polyol, polyester polyol, and polyether polyol. In order to improve adhesion to polyester films, polycarbonate polyol is preferred.

Polycarbonate polyols are obtained from polyhydric alcohols and carbonate compounds by a dealcoholization reaction. Examples of polyhydric alcohols include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 3,3-dimethylolheptane, 1,4-benzene dimethanol, 1,3-benzene dimethanol, 4,4'-naphthalenedimethanol, and 3,4'-naphthalenedimethanol. Examples of the carbonate compounds include dimethyl carbonate, diethyl carbonate, diphenyl carbonate, and ethylene carbonate, and examples of the polycarbonate polyol obtained from the reaction thereof include polyhexamethylene carbonate diol, polycyclohexylene carbonate diol, and the like. Among these, polyhexamethylene carbonate diol is preferable from the viewpoint of adhesion of the release layer to the polyester film.

As polyester polyols, polycarboxylic acids (malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, sebacic acid, fumaric acid, maleic acid, terephthalic acid, isophthalic acid, etc.) or their acid anhydrides and polyhydric alcohols (ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 2-methyl-1,3-propanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 2-methyl-2,4-pentanediol, 2-methyl-2-propyl-1,3-propanediol, 1,8-octanediol, Examples thereof include those obtained from the reaction of 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl-1,3-hexanediol, 2,5-dimethyl-2,5-hexanediol, 1,9-nonanediol, 2-methyl-1,8-octanediol, 2-butyl-2-ethyl-1,3-propanediol, 2-butyl-2-hexyl-1,3-propanediol, cyclohexanediol, bishydroxymethylcyclohexane, dimethanolbenzene, bishydroxyethoxybenzene, alkyldialkanolamines, lactone diol, etc.), and those having a derivative unit of a lactone compound such as polycaprolactone.

Examples of polyether polyols include polyethylene glycol, polypropylene glycol, polyethylene propylene glycol, polytetramethylene ether glycol, and polyhexamethylene ether glycol.

As low molecular weight polyols, there are no particular limitations, but examples thereof include those having a number average molecular weight of 60 or more and less than 400. For example, aliphatic diols having 2 to 9 carbon atoms, such as ethylene glycol, 1,3-propanediol, 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, 1,9-nonanediol, 2-methyl-1,8-octanediol, diethylene glycol, triethylene glycol, and tetraethylene glycol; Examples thereof include diols having an alicyclic structure having 6 to 12 carbon atoms, such as 1,4-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanediol, 1,4-bis(hydroxyethyl)cyclohexane, 2,7-norbornanediol, tetrahydrofurandimethanol, and 2,5-bis(hydroxymethyl)-1,4-dioxane; dimethylol alkanoic acids such as 2,2-dimethylolpropanoic acid and 2,2-dimethylolbutanoic acid; and low molecular weight polyhydric alcohols such as trimethylolpropane, pentaerythritol, and sorbitol. Among these, dimethylol alkanoic acid is preferable from the viewpoint of improving the stability of the aqueous dispersion of the urethane (meth)acrylate compound.

Examples of (meth)acrylate compounds include monofunctional (meth)acrylates, difunctional (meth)acrylates, and polyfunctional (meth)acrylates. Here, polyfunctional (meth)acrylate refers to a compound having three or more (meth)acrylate groups per molecule.

The (meth)acrylate compound may be a polymer or a monomer. From the viewpoint of reactivity with a silicone compound, a monomer is preferable.

As for monofunctional (meth)acrylates, there is no particular limitation. For example, alkyl (meth)acrylates such as methyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, cyclohexyl (meth)acrylate, and isobornyl (meth)acrylate; hydroxyalkyl (meth)acrylates such as hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, and hydroxybutyl (meth)acrylate; alkoxyalkyl (meth)acrylates such as methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate, methoxypropyl (meth)acrylate, and ethoxypropyl (meth)acrylate; aromatic (meth)acrylates such as benzyl (meth)acrylate and phenoxyethyl (meth)acrylate; Examples thereof include amino group-containing (meth)acrylates such as diaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, etc., ethylene oxide-modified (meth)acrylates such as methoxyethylene glycol (meth)acrylate, phenoxypolyethylene glycol (meth)acrylate, and phenylphenol ethylene oxide-modified (meth)acrylate, glycidyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, and (meth)acrylic acid.

As the bifunctional (meth)acrylate, there may be mentioned, but not limited to, alkanediol di(meth)acrylates such as 1,4-butanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, and tricyclodecanedimethylol di(meth)acrylate, bisphenol-modified di(meth)acrylates such as bisphenol A ethylene oxide-modified di(meth)acrylate and bisphenol F ethylene oxide-modified di(meth)acrylate, glycerin di(meth)acrylate, trimethylolpropane di(meth)acrylate, pentaerythritol di(meth)acrylate, dipentaerythritol di(meth)acrylate, polyethylene glycol di(meth)acrylate, Examples include polypropylene glycol di(meth)acrylate, urethane di(meth)acrylate, and epoxy di(meth)acrylate.

As the multifunctional (meth)acrylate, there may be mentioned, but not limited to, alkylene oxide-modified trimethylolpropane tri(meth)acrylate such as trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, ethylene oxide-modified trimethylolpropane tri(meth)acrylate, and propylene oxide-modified trimethylolpropane tri(meth)acrylate, isocyanuric acid-modified tri(meth)acrylate such as ethylene oxide-modified isocyanuric acid tri(meth)acrylate, and ε-caprolactone-modified tris(acryoxyethyl)isocyanurate, pentaerythritol tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, Examples thereof include alkylene oxide-modified pentaerythritol tetra(meth)acrylates such as dipentaerythritol tetra(meth)acrylate, tetramethylolmethane ethylene oxide-modified tetra(meth)acrylate, and ethylene oxide-modified pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, and dipentaerythritol hexa(meth)acrylate.

Among these, from the viewpoint of forming crosslinks more efficiently, bifunctional (meth)acrylates or polyfunctional (meth)acrylates are preferable, and polyfunctional (meth)acrylates are more preferable. Specifically, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, and dipentaerythritol hexa(meth)acrylate are preferable, and trimethylolpropane tri(meth)acrylate and dipentaerythritol hexa(tri)acrylate are more preferable.

When the release agent composition includes a compound containing a (meth)acryloyl group, the content of the compound containing a (meth)acryloyl group in the release agent composition is preferably in the range of 1 to 50 mass%, more preferably 1 to 40 mass%, even more preferably 2 to 30 mass%, and particularly preferably 2 to 10 mass%, as a proportion of the total nonvolatile components in the release agent composition. By setting the content to 1 mass% or more, the adhesion to the present polyester film can be improved. In addition, by setting the content to 50 mass% or less, sufficient release properties can be secured.

(((especially desirable form)))

From the viewpoint of obtaining excellent release properties, it is preferable that the release layer contain a silicone compound as the release agent.

In addition, from the viewpoint of obtaining excellent adhesion to the polyester film, it is preferable that the release agent composition further includes a compound containing a (meth)acryloyl group when the release agent includes a silicone compound, or that the release agent composition further includes a crosslinking agent when the release agent includes a long-chain alkyl.

In addition, from the viewpoint of further lowering the air leakage index and further improving the handling properties such as the rollability of the release film, it is preferable that the release agent include a long-chain alkyl group-containing compound.

In this way, the above particularly preferable form can be appropriately selected based on the priority characteristic.

(((Other ingredients)))

In addition, in a range that does not impair the gist of the present invention, in addition to the above components, additives such as binder resin, particles, antifoaming agents, coating improvers, surfactants, thickeners, organic lubricants, ultraviolet absorbers, antioxidants, foaming agents, dyes, and pigments may also be appropriately blended. The specific aspects of the binder resin that can be contained in the release agent composition are the same as those of the binder resin that can be contained in the above-described resin composition, and all of them can be used.

In addition, when using a silicone compound as a release agent, a catalytic amount of a platinum group metal catalyst or a reactive release regulator may be appropriately blended.

(((menstruum)))

The release agent composition may be diluted with a solvent to form a coating solution. That is, the release agent composition may be applied as a liquid coating solution to, for example, the polyester film, and dried or cured as necessary to form a release layer.

In addition, each component constituting the release agent composition (release agent, optionally added crosslinking agent and compound containing (meth)acryloyl group, other components, etc.) may be dissolved in a solvent or dispersed in a solvent.

In the case of a coating solution, the concentration of the total nonvolatile components of the release agent composition in the coating solution is preferably 0.1 to 50 mass%. When it is 0.1 mass% or more, a release layer having a desired thickness can be efficiently formed. On the other hand, when it is 50 mass% or less, the appearance of the release layer can be improved by suppressing the viscosity at the time of coating, and the stability in the coating solution can also be increased.

The specific aspects and preferred aspects of the solvent capable of diluting the heterocyclic composition are the same as those of the solvent capable of diluting the above-described resin composition, and all of them can be used.

It can be assumed that, among the release layer, unreacted substances, reacted compounds, or mixtures thereof of each component constituting the release agent composition (release agent, optionally added crosslinking agent and compound containing (meth)acryloyl group, other components, etc.) are present.

Additionally, analysis of each component in the heterogeneous layer can be performed using, for example, TOF-SIMS, ESCA, fluorescence X-ray, etc.

<Method of forming heterogeneous layer>

Next, a method for forming a release layer constituting a release film will be described. However, specific aspects and preferred aspects of the method for forming the release layer are the same as the method for forming the resin layer described above, and all of these can be used.

That is, it is preferable that the heteromorphic layer be formed by inline coating, which treats the film surface during the film forming process of the polyester film.

In addition, but not limited to the following, for example, in sequential biaxial stretching, a method of coating a uniaxially stretched film stretched in the longitudinal direction (vertical direction) and then stretching it in the transverse direction is excellent.

The amount of the nonvolatile component of the release layer applied is preferably 0.001 to 1.0 g/m2, more preferably 0.005 to 0.5 g/m2, and even more preferably 0.01 to 0.2 g/m2. When the amount of application is 0.001 g/m2 or more, sufficient release properties can be obtained. In addition, when the amount of application is 1.0 g/m2 or less, deterioration of the appearance of the coating film or insufficient curing of the coating film can be suppressed.

In addition, the amount of application can be calculated from the concentration of nonvolatile components of the application liquid, the amount of application before drying derived from the amount of application liquid consumed, the transverse elongation ratio, etc.

In addition, the amount of nonvolatile component applied is the amount applied to the release film, and for example, in the case of drying and stretching, it is the amount applied after drying and stretching.

<<<Properties of heteromorphic films>>>

The load length ratio (Rmr(80)) of the roughness curve at the cut level of 80% of the resin layer surface of the heterogeneous film is 94% or less.

The load length ratio (Rmr(c)) is one of the line roughness parameters (JIS B 0601), and represents the ratio of the load length ML(c) of the contour curve element at the cutting level c (height% or ㎛) to the evaluation length Ln, and is obtained from the following equation (3-1-1).

Here, the inventors of the present invention considered that the load length ratio (Rmr(80)) is effective as an index representing the uneven distribution of the uneven structure. For example, when the concave distribution is large, the load length ratio (Rmr(80)) value becomes small, and when the convex distribution is large, the load length ratio (Rmr(80)) value becomes large. When the load length ratio (Rmr(80)) is small, the gap between films when the film is wound into a roll shape becomes large, the easiness of air escape is improved, and the winding property, etc. can be improved.

The load length ratio (Rmr(80)) of the roughness curve at the cutting level of 80% is, as described above, 94% or less, preferably 90% or less, more preferably 76% or less, even more preferably 70% or less, particularly preferably 65% or less, and most preferably 58% or less. The lower limit is not particularly limited and is about 1%, preferably 4%, and more preferably 6%.

The above load length ratio (Rmr(80)) can be adjusted by the composition or content of the resin composition described above.

In addition, the load length ratio (Rmr(50)) of the roughness curve at the cutting level of 50% of the resin layer surface is preferably 60% or less, more preferably 40% or less, and even more preferably 20% or less. The lower limit is not particularly limited and is about 1%, preferably 3%, and more preferably 5%.

Here, the inventors of the present invention considered that, in addition to the load length ratio (Rmr (80)), considering the load length ratio (Rmr (50)) is also effective as an index representing the uneven distribution of the uneven structure. For example, even in the case of the same load length ratio (Rmr (80)) value, when the load length ratio (Rmr (50)) value is small, the convex shape is thin, and when the load length ratio (Rmr (50)) value is large, the convex shape is thick. Therefore, when the load length ratio (Rmr (50)) is small, the uneven shape becomes finer, and when the film is wound into a roll, the gap created between the films becomes larger, so that the easiness of air escape is improved, and the winding property, etc. can be improved.

The above load length ratio (Rmr(50)) can also be adjusted by the composition or content of the resin composition described above.

In addition, the arithmetic mean roughness (Ra) of the surface of the resin layer is preferably 5 nm or more, more preferably 10 nm or more, further preferably 20 nm or more, particularly preferably 30 nm or more, and most preferably 35 nm or more. The upper limit is not particularly limited, but is preferably 600 nm, more preferably 400 nm, and even more preferably 200 nm. When the arithmetic mean roughness (Ra) is 5 nm or more, it can be said that the resin layer has a fine uneven structure, and the handleability of the release film becomes good. In addition, when the arithmetic mean roughness (Ra) is 600 nm or less, it can be said that the uneven structure of the resin layer has a sufficiently fine shape.

Arithmetic mean roughness (Ra) is one of the linear roughness parameters (JIS B 0601) and represents the average value of the average elevation difference in the mean plane.

That is, when a portion of the standard length L is extracted, and the average line of this extracted portion is represented as the x-axis and the direction of the vertical magnification is represented as the y-axis to form a roughness curve as y = Z(x), it is obtained from the following equation (3-1-2).

In addition, the ten-point average roughness (Rzjis) of the surface of the resin layer is preferably 28 nm or more, more preferably 70 nm or more, further preferably 90 nm or more, and particularly preferably 120 nm or more. The upper limit is not particularly limited, but is preferably 800 nm, more preferably 600 nm, and further preferably 500 nm. When the ten-point average roughness (Rzjis) is 28 nm or more, it can be said that the resin layer has a sufficient uneven structure. In addition, when the ten-point average roughness (Rzjis) is 800 nm or less, it can be said that the uneven structure of the resin layer has a sufficiently fine shape.

The ten-point average roughness (Rzjis) is one of the line roughness parameters (JIS B 0601), and represents the sum of the average of the fifth from the maximum peak height (Zp) of the contour curve and the average of the fifth from the deepest valley depth (Zv) in the reference length L, and is obtained from the following equation (3-1-3).

The above arithmetic mean roughness (Ra) and ten-point average roughness (Rzjis) can be adjusted by the composition or content of the resin composition described above.

In addition, the load length ratio (Rmr(80)), load length ratio (Rmr(50)), arithmetic mean roughness (Ra) and ten-point average roughness (Rzjis) of the resin layer surface are measured by the method described in the examples using an atomic force microscope (scanning probe microscope). If the measurement is by an atomic force microscope (scanning probe microscope), it is possible to grasp a finer structure of the surface, and it becomes possible to obtain a value that strongly reflects the effect by the resin layer.

The tape peeling force of the release layer of the release film is preferably 500 mN/cm or less, more preferably 400 mN/cm or less, even more preferably 300 mN/cm or less, and particularly preferably 200 mN/cm or less. If the tape peeling force is 500 mN/cm or less, it can be said that the release film has sufficient releasability. The lower limit is not particularly limited, and is about 0.1 mN/cm.

In addition, the tape peeling force of the above heteromorphic layer can be measured by the method described in the examples.

The coefficient of static friction between the surface of the resin layer of the release film and the surface of the release layer is preferably 1.0 or less, more preferably 0.8 or less, even more preferably 0.6 or less, and particularly preferably 0.4 or less.

When a release film is wound into a roll, the friction coefficient between the resin layer surface and the release layer surface is important because the resin layer surface and the release layer surface come into contact.

Accordingly, when the static friction coefficient is within this range, the uneven structure of the resin layer improves the sliding properties and the handling properties of the release film improve.

In addition, the static friction coefficient can be measured by the method described in the examples.

As an index for evaluating the handling properties such as the windability of a release film, the air leakage index can be used. If the air leakage index is low, the air that has been rolled up when the release film is rolled up is likely to escape, and defects in the appearance of the roll such as wrinkles or mismatch of the end faces can be prevented. On the other hand, if the air leakage index is high, the air that has been rolled up escapes after a sufficient period of time, especially during conveyance, and there are cases where the film is misaligned in the direction of the winding core, or the misalignment causes scratches, which can be a problem. Such problems do not occur with release films.

The air leakage index should be, for example, 150,000 seconds or less. More preferably, it should be 100,000 seconds or less, even more preferably 70,000 seconds or less, and particularly preferably 30,000 seconds or less. If it is 150,000 seconds or less, it can be said to have a certain handling property.

In addition to being able to improve the air leakage index by the uneven structure of the resin layer, it is also possible to improve it by the roughness of the smooth surface of the polyester film. Specifically, it is preferable that the arithmetic mean roughness (Sa) of the polyester film surface opposite to the surface on which the resin layer is formed (i.e., the smooth surface) be either or both of 15 nm or less and 800 nm or less. Here, the opposite surface may be a film surface used for processing when the release film is used for various purposes, such as a release film for forming a green sheet of a laminated ceramic capacitor, an interlayer insulating resin release film, and a release film for dry film resist, and for example, various materials may be applied or laminated as described below.

In addition, when more precise processing is required, it is more preferable that the arithmetic mean roughness (Sa) of the polyester film surface on the opposite side (i.e., the smooth surface of the film used for processing) be 9 nm or less and the maximum peak height (Sp) be 500 nm or less, or both. In this way, when the smooth surface of the film is very smooth, more precise processing can be performed by utilizing the smoothness of the film, and in addition, the air leakage index is improved within the above range by the uneven structure of the resin layer, so that the windability is improved and the handling property of the release film is improved.

In this way, the air leakage index depends on the degree of smoothness of the polyester film surface on the opposite side to the surface on which the resin layer is formed. Even when smoothness is required by the polyester film, it becomes possible to obtain an effect of improving the handling properties by the uneven structure of the resin layer.

Additionally, the air leakage index can be measured by the method described in the examples.

<<<Uses of heteromorphic films>>>

The resin layer is characterized by being composed of a resin composition containing a specific compound and having a specific roughness structure, thereby forming a phase-separated structure even in a thin film, thereby being able to express a fine roughness structure. In addition, the resin layer is characterized by focusing on the load length ratio (Rmr(80)) that represents the roughness structure's roughness distribution.

This design concept enables precise control of the fine roughness structure, which is difficult to achieve with conventional particle mixing type film manufacturing methods. In addition, by having a specific roughness structure, the air permeability can be improved even in a thin film, making it possible to provide a release film with excellent handling properties.

The heteromorphic film can be used for various purposes to improve handling properties, and its uses are not particularly limited.

Among these, as described above, because of its fine uneven structure, when used for sheet molding, it has the advantage of exhibiting good windability and being unlikely to cause wrinkles even when winding a highly smooth film into a roll shape, and can be suitably used as a release film for sheet molding. As a release film for sheet molding, examples thereof include various release applications such as green sheet molding of multi-layer ceramic capacitors (MLCC), interlayer insulating resins, dry film resists (DFRs), and multilayer circuit boards. The release film is used as a support for its release application, for example. Among these, the release film can be suitably used as a support for ceramic green sheets in the manufacturing process of multi-layer ceramic capacitors, particularly multi-layer ceramic capacitors for automobiles.

A release film for sheet forming may be used in a process of forming various sheets, such as green sheets, by applying or laminating various materials on at least one surface of the film. It is preferable that the various materials be applied or laminated on the release layer surface.

<<<Polyester film roll>>>

The laminated polyester film of the present invention, as described above, is a laminated polyester film that can form a fine rough structure even in a thin film and has excellent handling properties when winding the film into a roll shape, etc.

As a specific embodiment, the following configuration can be suitably mentioned.

A polyester film roll formed by winding a polyester film and a laminated polyester film having a resin layer, which is a cured resin layer, on one side of the polyester film.

It is preferable that the above laminated polyester film is a polyester film roll that satisfies all of the requirements of (1) to (4) below.

(1) The above resin layer has a rough structure.

(2) The resin layer is a cured product of a cured resin composition containing (A) a release agent, (B) a crosslinking agent, and (D) fine particles.

(3) The average surface roughness (Sa) of the surface of the resin layer is 1 to 9 nm.

(4) The root mean square gradient (Sdq) of the surface of the resin layer is 0.40 to 0.80.

Here, (1) and (2) have already been explained and are the same as described above.

(3) Regarding the requirement, it is preferable that the average surface roughness (Sa) of the polyester film roll in question is 1 to 9 nm. The definition of the average surface roughness (Sa) has already been explained and is as described above.

In the case of a laminated polyester film, if the average surface roughness (Sa) of the resin layer surface is 9 nm or less, the smoothness of the resin layer surface is not lost, and defects such as pinholes due to fine unevenness on the surface of the laminated polyester film are unlikely to occur. In addition, if the average surface roughness (Sa) is 1 nm or more, the film surface becomes too flat, making it difficult for the adverse effect of being easily scratched to occur.

From the viewpoint of thinning of ceramic green sheets or pinhole suppression, the average surface roughness (Sa) of the resin layer surface of the laminated polyester film is more preferably 2 to 7 nm.

In addition, in the laminated polyester film, the surface on which the resin layer is provided is typically, as described later, the surface (opposite surface) opposite to the surface (processing surface) on which various materials are applied and laminated in the manufacture of ceramic layers, etc. However, even on the opposite surface, by lowering the average surface roughness (Sa) as described above, it is possible to prevent the unevenness of the opposite surface from being transferred to the processing surface, thereby preventing pinholes from occurring or the inability to respond to thinning due to the transferred unevenness.

(4) Regarding the requirement, it is preferable that the root mean square gradient (Sdq) of the polyester film roll in question is 0.40 to 0.80.

The inventors of the present invention have found that by making the root mean square gradient (Sdq) a certain value or higher by focusing on the shape of the convex portion of the surface of the resin layer, particularly the inclined structure, good air leakage between films can be exhibited when wound into a roll, thereby improving the windability.

The root mean square gradient (Sdq) is one of the surface roughness parameters obtained by measurement in accordance with ISO25178, and is expressed by the following equation (4-1-1).

The root mean square gradient (Sdq) represents the average size of the local gradient of the surface irregularities, with a larger value indicating a steeper surface.

As described above, the root mean square gradient (Sdq) of the resin layer surface is preferably 0.40 to 0.80. When the root mean square gradient (Sdq) is 0.80 or less, defects such as pin holes are unlikely to occur, so scratch resistance is maintained and it is easy to cope with thinning of the ceramic green sheet. When the root mean square gradient (Sdq) is 0.40 or more, good air leakage occurs between films, so that good windability can be achieved. In addition, since the film surface does not become extremely flat, the slipperiness of the film is maintained and scratches are unlikely to occur, so scratch resistance is maintained. In addition, it is easy to cope with elongation of the polyester film roll.

In addition, by satisfying the above range, even in the elongated roll film, the convex portion of the surface of the resin layer is unlikely to be deformed, so that a good roll appearance can be obtained.

The root mean square gradient (Sdq) is more preferably 0.40 to 0.60 from the viewpoint of improving scratch resistance and responding to the elongation of polyester film rolls and thinning of ceramic green sheets.

In addition, it is presumed that since the resin layer contains fine particles, the slope of the convex portion becomes steep, so that the root mean square gradient (Sdq) easily falls within the above-mentioned predetermined range, and good air leakage between films can be exhibited.

In the laminated polyester film, from the viewpoint of pinhole suppression, the maximum peak height (Sp) on the surface of the resin layer is, for example, 150 nm or less, preferably 100 nm or less, and more preferably 80 nm or less. There is no particular limitation on the lower limit of the maximum peak height (Sp) on the surface of the resin layer, but from the viewpoint of film handleability, it is preferably 10 nm or more, more preferably 15 nm or more, and even more preferably 20 nm or more.

Additionally, the definition of maximum mountain height (Sp) is as described above.

The protruding peak height (Spk) is one of the surface roughness parameters obtained by measurement in accordance with ISO25178. The protruding peak height (Spk) of the resin layer surface is preferably 70 nm or more, more preferably 100 nm or more, even more preferably 150 nm or more, and particularly preferably 200 nm or more.

By meeting the above range, even if the maximum height (Sp) of the unevenness of the surface of the resin layer is small due to the protrusions, the air leakage index is small and good film handling properties can be secured.

The protruding peak height (Spk) is not particularly limited, but is, for example, 500 nm or less.

The ratio (Sp/Sa) of the maximum height of the resin layer surface (Sp) to the average surface roughness (Sa) is preferably 30 or less, more preferably 25 or less. By setting the ratio (Sp/Sa) to 30 or less, there are no large protrusions on the surface of the resin layer, the occurrence of pinholes and the like is suppressed, and it becomes easier to respond to thinning. The ratio (Sp/Sa) is not particularly limited, but may be, for example, 1 or more, or 3 or more.

<<<Explanation of phrase>>>

In the present invention, even when referred to as a “film,” it is considered to include a “sheet,” and even when referred to as a “sheet,” it is considered to include a “film.”

In the present invention, when it is described as “X to Y” (X and Y are arbitrary numbers), unless specifically stated otherwise, it includes the meaning of “more than X and less than Y,” as well as the meaning of “preferably greater than X” or “preferably less than Y.”

Also, when it is written as “X or more” (where X is any number), it includes the meaning “preferably greater than X” unless otherwise stated, and when it is written as “Y or less” (where Y is any number), it also includes the meaning “preferably less than Y” unless otherwise stated.

Example

Hereinafter, the present invention will be described in more detail by examples.

However, the present invention is not limited to the following examples unless it exceeds the gist thereof.

<Evaluation method>

(1-1) Intrinsic viscosity (IV) of polyester

1 g of polyester from which incompatible components were removed was weighed, 100 mL of a mixed solvent of phenol/tetrachloroethane = 50/50 (mass ratio) was added, the solution was dissolved, and the viscosity was measured at 30°C using a viscosity measuring device "VMS-022UPC·F10" (manufactured by Rigosha Co., Ltd.).

(1-2) Average particle diameter

The average particle diameter was measured by observing 10 or more particles with a scanning electron microscope (SEM), and the average value was calculated as the average particle diameter (average primary particle diameter). In the case of non-spherical particles, the average value of the longest and shortest diameters was measured as the diameter of each particle.

(1-3) The uneven structure of the resin layer

Measurements were performed using a scanning probe microscope (SPM-9700 manufactured by Shimadzu Seisakusho Co., Ltd.) under the following conditions.

Probe: Silicon cantilever

Injection Mode: Dynamic Mode

Injection range: 25㎛×25㎛

Scan rate: 0.8㎐

Pixel count: 512×512 data points

From the obtained data, a cross-sectional shape with a width of 25 μm was observed, and if there were multiple convex or concave portions with a step exceeding 10 nm at positions of 80% or more, it was judged that the uneven structure was “present”, and if multiple convex or concave portions could not be confirmed, it was judged that the uneven structure was “absent.”

(1-4) Hansen solubility parameters (HSP) of each resin [δd, δp, δh]

About 0.05 g of the solid of each resin was placed in a 20 mL glass bottle, and the solvent was added so that the solid ratio became 1 mass%, stirred for 20 seconds, and then left to stand in an environment of 23°C. The glass bottle was checked after 24 hours, and if the solid dissolved, the solvent used was judged to be a good solvent, and if the solid was insoluble or swollen, the solvent used was judged to be a poor solvent, and each parameter [δd, δp, δh] of the Hansen solubility parameter (HSP) was calculated. The commercially available Hansen solubility parameter calculation software HSPiP was used to calculate the values. The solvent types used were selected according to Table 1 described above, and a total of 21 solvents were used for evaluation.

(1-5) Hansen solubility parameter (HSP) distance

Using the values of HSP measured by the method of (1-4) above, the HSP distance between each compound (A) and compound (B) was calculated from the following formula for each compound (A) and compound (B).

HSP distance={4×(δd ₁ -δd ₂ ) ² +(δp ₁ -δp ₂ ) ² +(δh ₁ -δh ₂ ) ² } ^0.5

Here, δd ₁ , δp ₁ and δh ₁ represent δd, δp and δh of compound (A), respectively, in the Hansen solubility parameters [δd, δp, δh], and δd ₂ , δp ₂ and δh ₂ represent δd, δp and δh of compound (B), respectively.

Also, δp ₁ ≤δp ₂ .

(1-6) Arithmetic mean roughness (Ra) and ten-point mean roughness (Rzjis) of the resin layer surface

From the data of the scanning probe microscope measured by the method of the above (1-3), a cross-sectional analysis of 25 ㎛ width was performed parallel to the tenter stretching direction (i.e., horizontal direction), and the arithmetic mean roughness (Ra) and the ten-point average roughness (Rzjis) were obtained. The cross-sectional analysis data of ten points were obtained at equal intervals in the film forming direction (i.e., vertical direction), and these were averaged to obtain the result.

(1-7) Load length ratio (Rmr(50)) and load length ratio (Rmr(80)) of the resin layer surface

By performing cross-sectional analysis of the injection probe microscope in the same manner as in the above (1-6), the load length ratio at 50% of the cutting level (Rmr(50)) and the load length ratio at 80% of the cutting level (Rmr(80)) were obtained, respectively. Cross-sectional analysis data of ten points were obtained at equal intervals in the film forming direction (i.e., vertical direction) and the average was obtained.

(1-8) Arithmetic mean roughness (Sa) and maximum height (Sp) of the surface opposite to the resin layer

The film surface was measured in an area of 640 ㎛ × 480 ㎛ using a non-contact surface/layer cross-section shape measurement system, VertScan (registered trademark) R550GML, manufactured by Ryoka Systems, Inc., with a CCD camera: SONY HR-50 1/3', objective lens: x20, optical tube: 1X Body, zoom lens: No Relay, wavelength filter: 530 white, and measurement mode: Wave. The output by fourth-order polynomial correction was used to obtain the arithmetic mean roughness (Sa) and maximum peak height (Sp) as a ten-point average.

(1-9) Coefficient of static friction

The coefficient of static friction between the resin layer surface and the opposite surface of the laminated polyester film was obtained by the following method.

A film was attached onto a smooth glass plate measuring 10 mm in width and 100 mm in length so that the side opposite to the side provided with the resin layer became the upper side. A film cut to 18 mm in width and 120 mm in length was placed thereon so that the side provided with the resin layer became the lower side, and a metal pin measuring 8 mm in diameter was additionally pressed onto the film, and the metal pin was allowed to slide in the length direction of the glass plate at a load of 30 g and 40 mm/min, and the frictional force was measured, and the maximum value immediately after sliding was evaluated as the static friction coefficient. In addition, the measurement was performed in an atmosphere of room temperature 23±1℃ and humidity 50±0.5%RH. In addition, the number of measurements (N) was 10, and the average value was adopted.

Coefficient of static friction (μs) = Fs / weight

(In the above formula, the unit of Fs is g-weight, and the unit of the additional load is g-weight)

(1-10) Air leakage index

The measurement was performed under an atmosphere of 23°C and 50%RH using a Digivac smoothness tester (manufactured by Toyo Seiki Co., Ltd., "DB-2") in accordance with JIS P8119. The pressure of the pressurizing device was 100 kPa, and the vacuum container had a volume of 38 ml. The time for 1 mL of air to flow, i.e. the time (in seconds) until the pressure inside the container changed from 50.7 kPa to 48.0 kPa, was measured, and 10 times the obtained number of seconds was taken as the air leakage index. The sample size of the test film was 70 mm square, and 20 sheets of the test film were laminated so that the front and back surfaces overlapped to obtain a test laminated film.

A hole with a diameter of 5 mm was drilled in the center of the test laminated film, and the air leakage index was measured as described above. The larger the value of this air leakage index, the longer it takes for air to leak from the gap between the films, indicating that the films are in closer contact with each other, and that there is a greater risk of wrinkles when the film is rolled.

<Materials used>

The polyesters used in the examples and comparative examples are as follows.

[Polyester (A)]

100 parts by mass of dimethyl terephthalate and 65 parts by mass of ethylene glycol were placed in an ester exchange reaction vessel equipped with a stirring device, a temperature increasing device, and an effluent separation tower, and heated to 150°C to melt dimethyl terephthalate.

Next, an ethylene glycol solution of magnesium acetate tetrahydrate was added so that the amount of magnesium acetate added to the obtained polyester was 0.09 mass%.

Thereafter, the temperature was raised to 225°C over 3 hours under normal pressure, and the mixture was stirred and maintained at 225°C for an additional 1 hour and 15 minutes while distilling off methanol to carry out an ester exchange reaction, thereby substantially completing the ester exchange reaction and obtaining a polyester oligomer.

Next, the above oligomer was transferred to a polycondensation reactor equipped with a stirrer and an outlet pipe.

An ethylene glycol solution of magnesium acetate tetrahydrate was added to the oligomer after transfer so that the amount of magnesium acetate added to the obtained polyester resin component was 0.09 mass%.

Thereafter, an ethylene glycol solution of phosphoric acid was added as a heat stabilizer so that the amount of phosphoric acid added to the obtained polyester was 0.017 mass%.

Next, an ethylene glycol solution of tetrabutyl titanate as a polycondensation catalyst was added to the oligomer so that the amount of titanium atoms in the obtained polyester was 4.5 mass ppm.

Thereafter, the pressure was reduced from 101.3 kPa to 0.4 kPa over 85 minutes and maintained at 0.4 kPa, the temperature was increased from 225°C to 280°C over 2 hours and maintained at 280°C for 1.5 hours to perform a dissolution condensation reaction, thereby obtaining a polyester (A) having an intrinsic viscosity (IV) of 0.63 dL/g.

[Polyester (B)]

In the method for producing polyester (A), a method similar to the method for producing polyester (A) was used, except that 0.3 mass% of silica particles having an average particle diameter of 2 µm were added to polyester (A) prior to melt polymerization, thereby obtaining polyester (B) having an intrinsic viscosity (IV) of 0.63 dL/g.

[Polyester (C)]

Among polyester (A), 0.75 mass% of alumina particles having an average particle size of 0.05 ㎛ were added and mixed using a vent-type twin-screw mixer, thereby obtaining polyester (C) having an intrinsic viscosity (IV) of 0.63 dL/g.

[Polyester (D)]

Instead of adding tetrabutyl titanate to polyester (A), antimony trioxide was added as a polycondensation catalyst so that the amount of antimony atoms was 300 mass ppm with respect to the obtained polyester resin fraction, and the same procedure as for polyester (A) was performed to obtain a polyester (D) having an intrinsic viscosity (IV) of 0.63 dl/g.

The resin composition obtained by stirring and mixing the composition shown in Table 1-2 below was diluted with water, and coating solutions 1-1 to 1-23 were prepared. The compounds used are as follows.

[Compound (A): Low polarity compound (1-IA)]

A wax emulsion obtained by adding 300 g of oxidized polyethylene wax having a melting point of 105°C, an acid value of 16 mgKOH/g, a density of 0.93 g/mL, and a number average molecular weight of 5000, 650 g of ion-exchanged water, 50 g of decaglycerin monooleate surfactant, and 10 g of 48% potassium hydroxide aqueous solution to a 1.5 L emulsifying facility equipped with a stirrer, a thermometer, and a temperature controller, replacing the mixture with nitrogen, sealing, stirring at high speed at 150°C for 1 hour, cooling to 130°C, and passing the mixture through a high-pressure homogenizer at 400 atm to cool to 40°C.

[Compound (A): Low polarity compound (1-IB)]

A four-necked flask was added with 200 parts by mass of xylene and 600 parts by mass of octadecyl isocyanate, and the mixture was heated with stirring. From the time when the xylene began to reflux, 100 parts by mass of polyvinyl alcohol having an average degree of polymerization of 500 and a degree of saponification of 88 mol% was added in small amounts at 10-minute intervals over a period of about 2 hours. After all of the polyvinyl alcohol had been added, reflux was performed for an additional 2 hours to terminate the reaction. The reaction mixture was cooled to about 80°C and then added into methanol, and the reaction product precipitated as a white precipitate. Therefore, the precipitate was filtered and separated, 140 parts by mass of xylene was added, and after heating to completely dissolve, methanol was added again to precipitate, and this operation of repeating several times, the precipitate was washed with methanol, dried, and pulverized to obtain.

[Compound (B): Binder resin (1-IIA)]

Water dispersion of acrylic resin polymerized with the following composition

Ethyl acrylate/n-butylacrylate/methyl methacrylate/N-methylolacrylamide/acrylic acid = 65/21/10/2/2 (mass %) emulsifying polymer (emulsifier: anionic surfactant)

[Compound (B): Binder resin (1-IIB)]

Polyvinyl alcohol with saponification degree of 88 mol% and polymerization degree of 500

[Compound (B): Binder resin (1-IIC)]

An ammonium group-containing polymer compound having a number average molecular weight of 30,000, which is a polymerization of the structural unit of the following formula (5-1-1)

[Compound (B): Binder resin (1-IID)]

A water dispersion of a polyester resin copolymerized with the following composition

Monomer composition: (acid component) terephthalic acid/isophthalic acid/5-sodium sulfoisophthalic acid//(diol component) ethylene glycol/1,4-butanediol/diethylene glycol = 56/40/4//70/20/10 (mol%)

[Compound (B): Crosslinker (1-IIIA)]

Melamine compound: hexamethoxymethylolmelamine

[Compound (B): Crosslinker (1-IIIB)]

Epocross (made by Nippon Shokubai Co., Ltd.), an oxazoline compound, oxazoline content 7.7 mmol/g

[Compound (C): Crosslinking catalyst (1-IV)]

2-Amino-2-methylpropanol hydrochloride

[Compound (D): Particulate (1-V)]

Silica particles with an average particle size of 0.005 ㎛

The HSP of each resin (1-IA) to (1-IIIB) measured by the method of (1-4) above is shown in Table 1-1.

(Example 1-1)

A mixed raw material in which polyester (A) and (B) were mixed in a ratio of 94 mass% and 6 mass%, respectively, was used as a raw material for the outermost layer (surface layer), and only polyester (A) was used as a raw material for the intermediate layer. Each of the raw materials for the outermost layer and the intermediate layer was supplied to two extruders, and each was melted at 285°C, and then co-extruded on a cooling roll set to 40°C in a layer configuration of 2 types and 3 layers (output amount of surface layer/intermediate layer/surface layer = 1/8/1) and then cooled and solidified to obtain an unstretched sheet.

Next, the film was stretched 3.5 times in the longitudinal direction while passing through a heated roll group at 85°C to obtain a uniaxially stretched film. On one side of the uniaxially stretched film, a coating solution 1-1 having a composition shown in Table 1-2 below was applied so that the coating amount (after dry stretching) was 0.10 g/m2, and then the film was guided to a tenter stretcher and stretched 4.3 times in the width direction at 100°C, and further heat-treated at 235°C, and then relaxation treatment was performed by 2% in the width direction to obtain a laminated polyester film having a thickness of 50 μm. The evaluation results are shown in Table 1-3.

(Examples 1-2 to 1-6)

A laminated polyester film was obtained in the same manner as in Example 1-1, except that the coating solution shown in Table 1-2 was used. The evaluation results are shown in Table 1-3.

(Example 1-7)

A mixed raw material in which polyester (A) and (C) were mixed in a ratio of 87 mass% and 13 mass%, respectively, was used as a raw material for one outermost layer (A layer), only polyester (A) was used as a raw material for the middle layer (B layer), and only polyester (A) was used as a raw material for one outermost layer (C layer). The raw materials for the A layer, the B layer, and the C layer were each supplied to three extruders, respectively, and after each was melted at 280°C, they were coextruded in a layer configuration of 2 types and 3 layers (output amount of surface layer/middle layer/surface layer = 1.6/27.8/1.6) on a cooling roll set to 25°C, and then cooled and solidified to obtain an unstretched sheet.

Next, the film was stretched 3.5 times in the longitudinal direction while passing through a heated roll group at 86°C to obtain a uniaxially stretched film. On one side (the surface of the C layer) of this uniaxially stretched film, a coating solution 1-1 having the composition shown in Table 1-2 below was applied so that the coating amount (after dry stretching) was 0.10 g/m2, and then the film was guided to a tenter stretcher and stretched 4.5 times in the width direction at 105°C, and further heat-treated at 230°C, and then relaxation treatment was performed by 2% in the width direction to obtain a laminated polyester film having a thickness of 31 μm. The evaluation results are shown in Table 1-3.

(Examples 1-8 to 1-25)

A laminated polyester film was obtained in the same manner as in Example 1-7, except that the coating solution shown in Table 1-2 was used and the coating amount (after drying and stretching) was changed to the coating amount shown in Table 1-3. The evaluation results are shown in Table 1-3.

(Example 1-26)

A laminated polyester film was obtained in the same manner as Example 1-10, except that only polyester (A) was used as the raw material for the outermost layer (layer A) on one side and only polyester (D) was used as the raw material for the middle layer. The evaluation results are shown in Table 1-3.

(Examples 1-27 to 1-30)

A laminated polyester film was obtained in the same manner as in Example 1-26, except that the coating solution shown in Table 1-2 was used and the coating amount (after drying and stretching) was changed to the coating amount shown in Table 1-3. The evaluation results are shown in Table 1-3.

(Comparative Example 1-1)

A polyester film was obtained in the same manner as in Example 1-1, except that the resin layer was not provided. The evaluation results are shown in Table 1-3.

(Comparative example 1-2)

A laminated polyester film was obtained in the same manner as in Example 1-1, except that the coating solution shown in Table 1-2 was used. The evaluation results are shown in Table 1-3.

(Comparative Example 1-3)

A polyester film was obtained in the same manner as in Example 1-7, except that the resin layer was not provided. The evaluation results are shown in Table 1-3.

(Comparative examples 1-4 to 1-5)

A laminated polyester film was obtained in the same manner as in Example 1-7, except that the coating solution shown in Table 1-2 was used. The evaluation results are shown in Table 1-3.

(Comparative Example 1-6)

A polyester film was obtained in the same manner as in Example 1-26, except that the resin layer was not provided. The evaluation results are shown in Table 1-3.

(Comparative Example 1-7)

A laminated polyester film was obtained in the same manner as in Example 1-26, except that the coating solution shown in Table 1-2 was used and the coating amount (after drying and stretching) was changed to the coating amount shown in Table 1-3. The evaluation results are shown in Table 1-3.

In addition, in the HSP distances in Table 1-3, for example, 1-I/1-II represents the HSP distances of 1-I and 1-II. More specifically, 1-I/1-II of Example 1-1 is the HSP distance of the low-polarity compound (1-IA) and the binder resin (1-IIA).

In addition, in the above Table 1-3, polyester film A is the polyester film of Example 1-1, polyester film B is the polyester film of Example 1-7, and polyester film C is the polyester film of Example 1-26.

As shown in the results in Table 1-3, Examples 1-1 to 1-6, which are laminated polyester films of the present invention, form a roughened structure as shown in Fig. 1 by including compounds (A) and (B), and further, since the load length ratio (Rmr (80)) at a cutting level of 80% is 76% or less, which is an appropriate roughened shape, and since the static friction coefficient is low as 1.0 or less, the slipperiness is good, and the air leakage index is 10,000 seconds or less, which is excellent in air permeability, it can be seen that the film is excellent in productivity such as windability.

On the one hand, since Comparative Example 1-1 does not have a resin layer, it does not have a rough structure. In addition, since Comparative Example 1-2 does not contain a compound (A), a rough structure is not formed. Therefore, these Comparative Examples were films with a high coefficient of friction and an air leakage index, poor slipperiness and air permeability, and poor handling properties.

In addition, Examples 1-7 to 1-30 are films having a low coefficient of static friction and an air leakage index, excellent slipperiness and rollability, and excellent productivity because they have an appropriate roughening structure. In addition, since the arithmetic mean roughness (Sa) and maximum peak height (Sp) of the opposite side of the resin layer are also low, they are excellent films that enable precise processing.

On the other hand, Comparative Examples 1-3 to 1-4 and 1-6 to 1-7, like Comparative Examples 1-1 to 1-2, did not have a resin layer or did not contain the compound (A), had a very high air leakage index, and also had a high static friction coefficient, so that the films had low slipperiness and rollability and low productivity. In addition, Comparative Example 1-5 had a rough structure, but did not have an appropriate rough structure because the load length ratio (Rmr (80)) was high. Therefore, the films had a low static friction coefficient, a high air leakage index, and low handleability.

<Evaluation method>

(2-1) Intrinsic viscosity (IV) of polyester

It was measured in the same way as (1-1) above.

(2-2) Average particle diameter

It was measured in the same way as (1-2) above.

(2-3) The uneven structure of the resin layer

It was measured in the same way as (1-3) above.

(2-4) Arithmetic mean roughness (Ra) and ten-point mean roughness (Rzjis) of the resin layer surface

In the same manner as in (1-6) above, the arithmetic mean roughness (Ra) and the ten-point mean roughness (Rzjis) were obtained.

(2-5) Load length ratio (Rmr(50)) and load length ratio (Rmr(80)) of the resin layer surface

In the same way as (1-7) above, Rmr(50) and Rmr(80) were obtained.

(2-6) Arithmetic mean roughness (Sa) and maximum height (Sp) of the surface opposite to the resin layer

In the same manner as in (1-8) above, the arithmetic mean roughness (Sa) and maximum mountain height (Sp) were obtained.

(2-7) Coefficient of static friction

The coefficient of static friction between the resin layer surface and the opposite surface of the laminated polyester film was obtained by the same method as (1-9) above.

(2-8) Air leakage index

The air leakage index was obtained in the same manner as in (1-10) above.

(2-9) Surface resistance value

Using a high-resistance resistivity meter (Hiresta UX MCP-HT800, manufactured by Mitsubishi Chemical Analytech Co., Ltd.) and a measurement probe (UR-100), the surface resistance value (Ω/□) of the resin layer was measured 1 minute after sufficient humidity control of a laminated polyester film (sample) under a measurement atmosphere of 23°C and 50% RH at an applied voltage of 100 V.

Additionally, “OVER” in Table 2-2 means that the upper measurement limit was exceeded.

(2-10) Surface charge

Two laminated polyester films were placed on a glass plate, with the resin layer side facing down, and pressed together twice with a rubber roller. The upper first film was quickly peeled off in a 90-degree direction, and immediately thereafter, the surface charge of the resin layer surface was measured using a digital electrostatic potential meter KSD-1000 manufactured by Kasuga Denki Co., Ltd.

The surface charge on the opposite side was measured using the same method as above, except that the film was placed on a glass plate with the resin layer side facing upward.

The measurements were performed twice, and the average of the absolute values was calculated.

In addition, the film was charged in advance using a discharger, and the test was conducted after confirming that the surface charge was 0 kV.

The absolute value of the surface charge is preferably 9.0 kV or less, more preferably 3.0 kV or less, and even more preferably 1.0 kV or less.

<Materials used>

The polyester used in the examples and comparative examples is as described above.

The resin composition obtained by stirring and mixing according to the composition shown in Table 2-1 below was diluted with water, and coating solutions 2-1 to 2-13 were adjusted. The compounds used were as follows.

[Compound (A-a): Antistatic agent (2-IA)]

An ammonium group-containing polymer compound having a number average molecular weight of 30,000, which is a polymerization of the structural unit of the following formula (5-2-1)

[Compound (A-a): Antistatic agent (2-IB)]

Antistatic agent having a number average molecular weight of 50,000, comprising a structural unit of the following formula (5-2-2)

[Compound (A-a): Antistatic agent (2-IC)]

A polymer compound having a number average molecular weight of 30,000, wherein the structural unit of the above formula (5-2-1) and the structural unit of the following formula (5-2-3) are copolymerized at a weight ratio of 95/5.

[Compound (B): Binder resin (2-IIA)]

Dissolution agent: A wax emulsion obtained by adding 300 g of oxidized polyethylene wax having a melting point of 105°C, an acid value of 16 mgKOH/g, a density of 0.93 g/mL, and a number average molecular weight of 5000, 650 g of ion-exchanged water, 50 g of decaglycerin monooleate surfactant, and 10 g of 48% potassium hydroxide aqueous solution to a 1.5 L emulsifying facility equipped with a stirrer, a thermometer, and a temperature controller, replacing the mixture with nitrogen, sealing, stirring at high speed at 150°C for 1 hour, cooling to 130°C, and passing the mixture through a high-pressure homogenizer at 400 atm to cool to 40°C.

[Compound (B): Binder resin (2-IIB)]

Hereinafter, the reaction mixture will be described in more detail. Hereinafter, a four-necked flask will be added 200 parts by mass of xylene and 600 parts by mass of octadecyl isocyanate, and the mixture will be heated with stirring. From the time when the xylene began to reflux, 100 parts by mass of polyvinyl alcohol having an average degree of polymerization of 500 and a degree of saponification of 88 mol% was added in small amounts at 10-minute intervals over a period of about 2 hours. After all of the polyvinyl alcohol had been added, reflux was performed for an additional 2 hours to complete the reaction. The reaction mixture was cooled to about 80°C and then added into methanol. The reaction product precipitated as a white precipitate, so the precipitate was filtered off, 140 parts by mass of xylene was added, heated to completely dissolve, and then methanol was added again to precipitate. This procedure was repeated several times, and the precipitate was washed with methanol, dried, and pulverized to obtain a.

[Compound (B): Binder resin (2-IIC)]

Polyvinyl alcohol with saponification degree of 88 mol% and polymerization degree of 500

[Compound (B): Binder resin (2-IID)]

Aqueous dispersion of acrylic resin polymerized with the following composition

An emulsifying polymer of acrylic resin composed mainly of methyl methacrylate, ethyl methacrylate, ethyl acrylate, acrylonitrile, and N-methylolacrylamide (emulsifier: anionic surfactant)

[Compound (B): Binder resin (2-IIE)]

Water dispersion of acrylic resin polymerized with the following composition

Ethyl acrylate/n-butylacrylate/methyl methacrylate/N-methylolacrylamide/acrylic acid = 65/21/10/2/2 (mass %) emulsifying polymer (emulsifier: anionic surfactant)

[Compound (B): Crosslinker (2-III)]

Melamine compound: hexamethoxymethylolmelamine

[Compound (C): Crosslinking catalyst (2-IV)]

2-Amino-2-methylpropanol hydrochloride

(Example 2-1)

A mixed raw material in which polyesters (A) and (B) were mixed in a ratio of 94 mass% and 6 mass%, respectively, was used as a raw material for the outermost layer (surface layer), and only polyester (A) was used as a raw material for the intermediate layer. Each of the raw materials for the outermost layer and the intermediate layer was supplied to two extruders, and each was melted at 285°C, then co-extruded on a cooling roll set to 40°C in a layer configuration of 2 types and 3 layers (output amount of surface layer/intermediate layer/surface layer = 1/8/1) and cooled and solidified to obtain an unstretched sheet.

Next, the film was stretched 3.5 times in the longitudinal direction while passing through a group of heated rolls at 85°C to obtain a uniaxially stretched film. On one side of the uniaxially stretched film, a coating solution 2-1 having a composition shown in Table 2-1 below was applied so that the coating amount (after dry stretching) was 0.06 g/m2, and then the film was guided to a tenter stretcher and stretched 4.3 times in the width direction at 100°C, and further heat-treated at 235°C, and then relaxation treatment was performed by 2% in the width direction to obtain a laminated polyester film having a thickness of 50 μm. The evaluation results are shown in Table 2-2.

(Examples 2-2 to 2-10)

A laminated polyester film was obtained in the same manner as in Example 2-1, except that the coating solution shown in Table 2-1 was used. The evaluation results are shown in Table 2-2.

(Example 2-11)

A mixed raw material in which polyester (A) and (C) were mixed in a ratio of 87 mass% and 13 mass%, respectively, was used as a raw material for one outermost layer (A layer), only polyester (A) was used as a raw material for the middle layer (B layer), and only polyester (A) was used as a raw material for one outermost layer (C layer). The raw materials for the A layer, the B layer, and the C layer were each supplied to three extruders, respectively, and after each was melted at 280°C, they were coextruded in a layer configuration of 2 types and 3 layers (output amount of surface layer/middle layer/surface layer = 1.6/27.8/1.6) on a cooling roll set to 25°C, and then cooled and solidified to obtain an unstretched sheet.

Next, the film was stretched 3.5 times in the longitudinal direction while passing through a heated roll group at 86°C to obtain a uniaxially stretched film. On one side (the surface of the C layer) of this uniaxially stretched film, a coating solution 2-1 having the composition shown in Table 2-1 below was applied so that the coating amount (after dry stretching) was 0.10 g/m2, and then the film was guided to a tenter stretcher and stretched 4.5 times in the width direction at 105°C, and further heat-treated at 230°C, and then relaxation treatment was performed by 2% in the width direction to obtain a laminated polyester film having a thickness of 31 μm. The evaluation results are shown in Table 2-2.

(Example 2-12)

A laminated polyester film was obtained in the same manner as Example 2-11, except that the coating solution shown in Table 2-1 was changed to the coating amount shown in Table 2-2. The evaluation results are shown in Table 2-2.

(Example 2-13)

A laminated polyester film was obtained in the same manner as Example 2-11, except that only polyester (A) was used as the raw material for the outermost layer (surface layer) and only polyester (D) was used as the raw material for the middle layer. The evaluation results are shown in Table 2-2.

(Example 2-14)

A laminated polyester film was obtained in the same manner as Example 2-13, except that the coating solution shown in Table 2-1 was changed to the coating amount shown in Table 2-2. The evaluation results are shown in Table 2-2.

(Comparative Example 2-1)

A polyester film was obtained in the same manner as in Example 2-1, except that the resin layer was not provided. The evaluation results are shown in Table 2-2.

(Comparative examples 2-2 to 2-3)

A laminated polyester film was obtained in the same manner as in Example 2-1, except that the coating solution shown in Table 2-1 was used and the coating amount (after drying and stretching) was changed to the coating amount shown in Table 2-2. The evaluation results are shown in Table 2-2.

(Comparative Example 2-4)

A polyester film was obtained in the same manner as in Example 2-11, except that the resin layer was not provided. The evaluation results are shown in Table 2-2.

(Comparative Example 2-5)

A polyester film was obtained in the same manner as in Example 2-13, except that the resin layer was not provided. The evaluation results are shown in Table 2-2.

(Comparative Example 2-6)

A laminated polyester film was obtained in the same manner as in Example 2-13, except that the coating solution shown in Table 2-1 was used and the coating amount (after drying and stretching) was changed to the coating amount shown in Table 2-2. The evaluation results are shown in Table 2-2.

In addition, in the above Table 2-2, polyester film A is the polyester film of Example 2-1, polyester film B is the polyester film of Example 2-11, and polyester film C is the polyester film of Example 2-13.

As shown in the results in Table 2-2, Examples 2-1 to 2-10, which are laminated polyester films having antistatic performance, form a roughened structure by including compounds (Aa) and (B), and further, the load length ratio (Rmr(80)) at a cutting level of 80% is 85% or less, so that it is an appropriate roughened shape, a low coefficient of static friction of 1.0 or less, good slipperiness, and excellent productivity such as windability. In addition, it can be seen that by setting the surface resistance value to 1×10 ¹³ Ω/□ or less, the film has a low charge amount and low adhesion of foreign substances or influence on a secondary processing layer.

On the one hand, since Comparative Example 2-1 does not have a resin layer, it does not have a rough structure and has a high surface resistance value. In addition, since Comparative Example 2-2 has a high surface resistance value, the amount of charge on the film surface is large. In addition, since Comparative Example 2-3 has a high surface resistance value, the amount of charge on the film surface is high, and furthermore, since the load length ratio (Rmr(80)) at the cutting level 80% is greater than 85%, the rough structure is not formed, so the friction coefficient is high, and the film has poor slipperiness and air permeability and poor handling properties.

In addition, Examples 2-11 to 2-14 are films with excellent productivity, which have a low coefficient of static friction and an air leakage index, excellent slipperiness and rollability, and can also reduce the surface charge of the film because they have an appropriate roughening structure. In addition, since the arithmetic mean roughness (Sa) and maximum peak height (Sp) of the opposite side of the resin layer are also low, they are excellent films that enable precise processing.

On the other hand, Comparative Examples 2-4 to 2-5, like Comparative Example 2-1, did not have a resin layer, so that in some cases, the load length ratio (Rmr(80)) at the cutting level 80% was larger than 85%, the air leakage index was very high, the static friction coefficient was also high, and the surface charge of the film was also high, so that the slipperiness and windability were low and the productivity was low. In addition, Comparative Example 2-6 had a resin layer but did not have an uneven structure, and since the load length ratio (Rmr(80)) was high, it did not have an appropriate uneven structure. Therefore, the static friction coefficient was high, the air leakage index was very high, and the handling properties were low.

<Evaluation method>

(3-1) Intrinsic viscosity (IV) of polyester

It was measured in the same way as (1-1) above.

(3-2) Average particle diameter

It was measured in the same way as (1-2) above.

(3-3) The uneven structure of the resin layer

It was measured in the same way as (1-3) above.

(3-4) Hansen solubility parameters (HSP) of each resin [δd, δp, δh]

It was measured in the same way as (1-4) above.

(3-5) Hansen solubility parameter (HSP) distance

It was measured in the same way as (1-5) above.

(3-6) Arithmetic mean roughness (Ra) and ten-point mean roughness (Rzjis) of the resin layer surface

In the same manner as in (1-6) above, the arithmetic mean roughness (Ra) and the ten-point mean roughness (Rzjis) were obtained.

(3-7) Load length ratio (Rmr(50)) and load length ratio (Rmr(80)) of the resin layer surface

In the same way as (1-7) above, Rmr(50) and Rmr(80) were obtained.

(3-8) Tape peeling force of heterogeneous layer

An adhesive tape (manufactured by Nitto Denko Co., Ltd., “No. 31B”) cut to 5 cm width was pressed once with a 2 kg rubber roller on the surface of the release layer of the release film, and the peeling force was measured after leaving it at room temperature for 1 hour. The peeling force was measured by performing 180° peeling using a small tabletop tester “EZ Graph” (manufactured by Shimadzu Seisakusho Co., Ltd.) under the condition of a tensile speed of 300 mm/min.

(3-9) Adhesion of the coating layer to the heterogeneous layer

The release layer surface of the release film was rubbed five times with a tentacle, and the presence or absence of the release layer peeling off was judged using the following judgment criteria.

《Judging Criteria》

○: No peeling of the coating is visible, or the coating turns white but does not peel off

×: The detachment of the film was confirmed.

(3-10) Coefficient of static friction

The coefficient of static friction between the surface of the resin layer of the release film and the surface of the release layer was obtained by the following method.

A film was attached so that the release layer surface became the upper surface on a smooth metal plate 10 mm in width and 100 mm in length. A film cut to 18 mm in width and 120 mm in length was placed thereon so that the surface provided with the resin layer became the lower surface, and a metal pin having a diameter of 8 mm was additionally pressed on the film, and the metal pin was allowed to slide in the longitudinal direction of the glass plate at a load of 30 g and 40 mm/min, and the frictional force was measured, and the maximum value immediately after sliding was evaluated as the static friction coefficient. In addition, the measurement was performed in an atmosphere of room temperature 23±1℃ and humidity 50±0.5%RH. In addition, the number of measurements (N) was three times, and the average value was adopted.

Coefficient of static friction (μs) = Fs / weight load

(In the above formula, the unit of Fs is g-weight, and the unit of the additional load is g-weight)

(3-11) Air leakage index

The air leakage index was obtained in the same manner as in (1-10) above.

<Materials used>

The polyester used in the examples and comparative examples is as described above.

The resin composition obtained by stirring and mixing the composition shown in Table 3-2 below was diluted with water, and coating solutions 3-A1 to 3-A7 were prepared. The compounds used are as follows.

[Compound (A): Low polarity compound (3-I)]

In a 1.5 L emulsifying facility equipped with a stirrer, a thermometer and a temperature controller, 300 g of oxidized polyethylene wax having a melting point of 105°C, an acid value of 16 mgKOH/g, a density of 0.93 g/mL and a number average molecular weight of 5000, 650 g of ion-exchanged water, 50 g of decaglycerin monooleate surfactant and 10 g of 48% potassium hydroxide aqueous solution were added, replaced with nitrogen, sealed and stirred at high speed at 150°C for 1 hour, cooled to 130°C, passed through a high-pressure homogenizer at 400 atm and cooled to 40°C to obtain a wax emulsion.

[Compound (B): Binder resin (3-IIA)]

Water dispersion of acrylic resin polymerized with the following composition

Ethyl acrylate/n-butylacrylate/methyl methacrylate/N-methylolacrylamide/acrylic acid = 65/21/10/2/2 (mass %) emulsifying polymer (emulsifier: anionic surfactant)

[Compound (B): Binder resin (3-IIB)]

A water dispersion of a polyester resin copolymerized in the following composition

Monomer composition: (acid component) terephthalic acid/isophthalic acid/5-sodium sulfoisophthalic acid//(diol component) ethylene glycol/1,4-butanediol/diethylene glycol = 56/40/4//70/20/10 (mol%)

[Compound (B): Binder resin (3-IIC)]

An ammonium group-containing polymer compound having a number average molecular weight of 30,000, which is a polymerization of the structural unit of the following formula (5-3-1)

[Compound (B): Crosslinker (3-III)]

Melamine compound: hexamethoxymethylolmelamine

[Compound (C): Crosslinking catalyst (3-IV)]

2-Amino-2-methylpropanol hydrochloride

[Compound (D): Particulate (3-V)]

Silica particles with an average particle size of 0.005 ㎛

The HSP of each resin (3-I) to (3-III) measured by the method of (3-4) above is shown in Table 3-1.

The release agent composition obtained by stirring and mixing the composition shown in Table 3-3 below was diluted with water, and coating solutions 3-B1 to 3-B3 were prepared. The compounds used are as follows.

[Lee Brothers (3-VIA)]

Aqueous dispersion of vinyl-containing polydimethylsiloxane having a vinyl group content of 0.16 mmol/g (emulsifier: nonionic surfactant)

[Lee Brothers (3-VIB)]

Aqueous dispersion of hydrogen-containing polydimethylsiloxane having a Si-H group content of 7.8 mmol/g (emulsifier: nonionic surfactant)

[Lee Brothers (3-VIC)]

Long-chain alkyl group-containing compound obtained by adding octadecyl isocyanate to polyvinyl alcohol having an average polymerization degree of 500 and a saponification degree of 88 mol%

[Bridge (3-VII)]

Partially etherified melamine having methylol, methoxy and imino groups

[Compound containing (meth)acryloyl group (3-VIII)]

A water dispersion of a mixture of a polycarbonate-based urethane resin and a (meth)acrylate compound having the following composition

An aqueous dispersion of a mixture of urethane (meth)acrylate and (meth)acrylate compounds excluding urethane (meth)acrylate, wherein 50 parts by mass of a polyurethane (meth)acrylate resin, wherein the polyhexamethylene carbonate diol unit having a molecular weight of 1100: a dimethylol propionic acid unit: a hydrogenated xylylene diisocyanate unit: a dipentaerythritol pentaacrylate unit = 11:7:40:42 (mol%) is mixed, 27 parts by mass of dipentaerythritol hexaacrylate, and 23 parts by mass of trimethylol propane triacrylate, is mixed.

(Example 3-1)

Only polyester (A) was used as the raw material for the outermost layer (surface layer), and only polyester (D) was used as the raw material for the middle layer. The raw materials for the outermost layer and the middle layer were each supplied to two extruders, each melted at 280°C, and then co-extruded on a cooling roll set to 25°C in a layer configuration of 2 types and 3 layers (output amount of surface layer/middle layer/surface layer = 1.6/27.8/1.6), and then cooled and solidified to obtain an unstretched sheet.

Next, the film was stretched 3.5 times in the longitudinal direction while passing through a group of heated rolls at 86°C to obtain a uniaxially stretched film. On one side of the uniaxially stretched film, a coating solution 3-A1 having a composition shown in Table 3-2 below was applied so that the coating amount (after dry stretching) was 0.10 g/m2, and on the opposite side, a coating solution 3-B1 having a composition shown in Table 3-3 below was applied so that the coating amount (after dry stretching) was 0.06 g/m2, and then the film was guided to a tenter stretcher and stretched 4.5 times in the width direction at 105°C, and further heat-treated at 230°C, and then relaxation treatment was performed by 2% in the width direction to obtain a release film having a polyester film thickness of 31 μm. The evaluation results are shown in Table 3-4.

(Examples 3-2 to 3-14)

A release film was obtained in the same manner as in Example 3-1, except that the coating solutions shown in Tables 3-2 and 3-3 were used and the coating amount (after dry stretching) was set to the coating amount shown in Table 3-4. The evaluation results are shown in Table 3-4.

(Comparative Example 3-1)

A polyester film was obtained in the same manner as in Example 3-1, except that the resin layer and release layer were not provided. The evaluation results are shown in Table 3-4.

(Comparative Example 3-2)

A polyester film having a resin layer was obtained in the same manner as Example 3-1, except that the coating solution shown in Table 3-2 was used, the coating amount (after drying and stretching) was set to the coating amount shown in Table 3-4, and no release layer was provided. The evaluation results are shown in Table 3-4.

(Comparative Example 3-3)

A polyester film having a release layer was obtained in the same manner as Example 3-1, except that the coating solution shown in Table 3-3 was used, the coating amount (after drying and stretching) was set to the coating amount shown in Table 3-4, and the resin layer was not provided. The evaluation results are shown in Table 3-4.

In addition, in the HSP distances in Table 3-4, for example, 3-I/3-II represents the HSP distances of 3-I and 3-II. More specifically, 3-I/3-II of Example 3-1 is the HSP distance of the low-polarity compound (3-I) and the binder resin (3-IIA).

As shown in the results in Table 3-4, Examples 3-1 to 3-14, which are heteromorphic films, contain compounds (A) and (B), and have a load length ratio (Rmr (80)) of 94% or less at a cutting level of 80%, an appropriate uneven shape, a low static friction coefficient of 1.0 or less, good slipperiness, and excellent air permeability with an air leakage index of 150,000 seconds or less, so it can be seen that the films are excellent in productivity such as windability.

The laminated polyester film of the present invention has an advantage in that, because the surface of the resin layer has a fine uneven structure, when used for sheet molding, for example, even when a very smooth film is wound into a roll, it exhibits good windability and wrinkles are unlikely to occur.

In addition, since the laminated polyester film of the present invention can form a resin layer into a thin film, it can also respond to the thin film elongation of the polyester film, and can contribute to the improvement of productivity by reducing the frequency of product roll switching during processing.

Therefore, the laminated polyester film of the present invention can be suitably used as a polyester film for sheet forming having excellent surface smoothness, and its industrial utility value is high.

In addition, since the laminated polyester film having antistatic performance of the present invention has a fine uneven structure on the surface of the resin layer, when used for sheet molding, for example, there is an advantage in that even when a very smooth film is wound into a roll, it exhibits good windability and wrinkles are unlikely to occur.

In addition, the laminated polyester film having antistatic performance of the present invention has an advantage in that, since the surface of the resin layer has a fine uneven structure, when used for, for example, sheet molding, the surface resistance value of the resin layer surface is low, so that surface charging of the film can be suppressed, and by preventing the attachment of foreign substances, defects during processing utilizing the high smoothness of the film surface can be prevented.

In addition, since the laminated polyester film having the antistatic performance of the present invention can form a resin layer into a thin film, it can also respond to the thin film elongation of the polyester film, and can contribute to the improvement of productivity by reducing the frequency of product roll switching during processing.

Therefore, the laminated polyester film having antistatic performance of the present invention can be suitably used as a polyester film for sheet forming having excellent surface smoothness, and its industrial utility value is high.

In addition, since the release film of the present invention has a fine uneven structure on the surface of the resin layer, when used for sheet molding, for example, there is an advantage in that even when a very smooth film is wound into a roll, it exhibits good windability and wrinkles are unlikely to occur.

In addition, since the release film of the present invention can form a resin layer into a thin film, it can also respond to the thin film elongation of the release film, and can contribute to the improvement of productivity by reducing the frequency of product roll switching during processing.

Therefore, the release film of the present invention can be suitably used as a release film for sheet molding having excellent surface smoothness, and its industrial utility value is high.

Claims (11)

A laminated polyester film comprising a polyester film and a resin layer formed by a resin composition on at least one side of the polyester film, wherein the laminated polyester film satisfies all of the following requirements (1) to (3).
(1) The above resin layer has a rough structure.
(2) The resin composition comprises the following compounds (A) and (B).
(A) Low polarity compound
(B) At least one selected from the group consisting of a binder resin and a crosslinking agent.
(3) The load length ratio (Rmr(80)) of the roughness curve at the cutting level of 80% of the surface of the resin layer as measured by a scanning probe microscope is 76% or less. A laminated polyester film, wherein in the first paragraph, the load length ratio (Rmr(50)) of the roughness curve at a cut level of 50% of the surface of the resin layer as measured by a scanning probe microscope is 60% or less. A laminated polyester film according to claim 1 or 2, wherein the arithmetic mean roughness (Ra) of the surface of the resin layer as measured by a scanning probe microscope is 20 nm or more. A laminated polyester film according to any one of claims 1 to 3, wherein the ten-point average roughness (Rzjis) of the surface of the resin layer as measured by a scanning probe microscope is 70 nm or more. A laminated polyester film according to any one of claims 1 to 4, having an air leakage index of 130,000 seconds or less. A laminated polyester film according to any one of claims 1 to 5, wherein the low-polarity compound comprises at least one selected from the group consisting of wax and long-chain alkyl group-containing compounds. A laminated polyester film according to any one of claims 1 to 6, wherein the binder resin comprises at least one selected from the group consisting of (meth)acrylic resin, polyvinyl alcohol, and ion-conductive polymer compounds. A laminated polyester film according to any one of claims 1 to 7, wherein the crosslinking agent comprises at least one selected from the group consisting of a melamine compound and an oxazoline compound. A laminated polyester film according to any one of claims 1 to 8, wherein the resin composition contains a crosslinking catalyst as compound (C). A laminated polyester film according to any one of claims 1 to 9, wherein the resin composition contains fine particles as the compound (D). A laminated polyester film used as a support for a ceramic green sheet in a manufacturing process of a laminated ceramic capacitor according to any one of claims 1 to 10.