TW202408816A - Biaxially oriented multilayer polyester film - Google Patents

Abstract

To provide a biaxially oriented multilayer polyester film that, in comparison with conventional technology, can more effectively prevent the occurrence of pinholes and winding creases in a production process for a resin sheet such as a ceramic green sheet. A biaxially oriented multilayer polyester film having an A layer and a B layer, wherein the A layer contains particles, the surface roughness of the A layer has a maximum peak height (SRp) of 1.0 [mu]m or less, and the relationship between the maximum size Dmax and the minimum size Dmin of the particles within the polyester film satisfies formula 1 (formula 1: 0.5 ≤ (Dmax-Dmin) ≤ 5.5), the biaxially oriented multilayer polyester film being usable in a mold release film for resin sheet formation.

Description

Biaxially aligned laminated polyester film and release film

The present invention relates to a biaxially aligned laminated polyester film used in a release film for forming a resin sheet. In particular, the present invention is used as a base material in a release film for forming a resin sheet.

Release films with polyethylene terephthalate films as the base material are used for the molding of ceramic products such as multilayer ceramic capacitors and ceramic substrates. In recent years, with the progress of miniaturization and high capacity of multilayer ceramic capacitors, the thickness of ceramic green sheets has also gradually tended to be thinner. With the further thinning of green sheets, especially when it is desired to mold thin film green sheets with a thickness of less than 1μm, if there are coarse protrusions on the release surface side of the release film, when the ceramic slurry is applied on the release film, there will be slurry shrinkage (cissing) or pinholes, and defects such as green sheet fracture will occur when the green sheet is peeled off, which sometimes causes the problem of deterioration of the defect rate of multilayer ceramic capacitors.

In order to solve the above problems, a film substantially free of lubricant on the surface coated with a release agent has been reported (e.g., Patent Document 1). [Prior Art Document] [Patent Document]

[Patent Document 1] Japanese Patent Application Publication No. 2003-133170.

[The problem that the invention wants to solve]

However, in recent years, the further thinning of ceramic green sheets, especially when molding thin-film ceramic green sheets with a thickness of less than 1 μm, has caused various problems that have never occurred before. For example, the thin-film ceramic green sheets may have pinhole problems. For example, it is believed that during winding, the coarse protrusions on the side opposite to the release surface are transferred to the release surface side, resulting in pinholes, particles falling off the film surface, and the deterioration of the planarity of the release surface side, resulting in poor formation.

The present invention is based on the above-mentioned prior art. That is, the purpose is to provide a biaxially aligned laminated polyester film which can more effectively suppress the generation of pinholes in the manufacturing step of resin sheets such as ceramic green sheets compared with the prior art.

As a result of actively examining to solve the above-mentioned problem, the inventors found that the above-mentioned purpose can be achieved by a release film having the following structure, thereby completing the present invention. [Means for solving the problem]

That is, the present invention has the following configuration. [1] A biaxially aligned laminated polyester film having an A layer and a B layer; The aforementioned A layer contains particles; The maximum peak height (SRp) of the surface roughness of the aforementioned A layer is 1.0 μm or less; The relationship between the maximum size Dmax and the minimum size Dmin of particles in the polyester film satisfies the following (Formula 1): 0.5μm ≦ (Dmax−Dmin) ≦ 5.5μm (Formula 1) The aforementioned biaxially aligned laminated polyester film is used as a release film for forming resin sheets. [2] Biaxially aligned laminated polyester film as described in [1], wherein The aforementioned B layer does not substantially contain particles with a particle size of 1.0 μm or more; The maximum peak height (SRp) of the surface of the B layer is 1.0 μm or less. [3] The biaxially aligned laminated polyester film as described in [1] or [2], wherein the ratio of the hole size t in the film to the average particle diameter d of the particles satisfies the following (Formula 2): 0.5 ≦ t/d ≦ 3.0 (Equation 2). [4] The biaxially aligned laminated polyester film described in [1], with a film thickness of 12 μm or more and 50 μm or less. [5] A release film with: The biaxially aligned laminated polyester film as described in any one of [1] to [4]; and Functional layer; The functional layer is arranged on the side of the B layer of the biaxially aligned laminated polyester film. [Invention effect]

The present invention provides a biaxially aligned multilayer polyester film, which can reduce the shedding of particles and suppress coarse protrusions, and is used for a release film for forming a resin sheet. For example, the present invention can suppress the formation of pinholes caused by the transfer of coarse protrusions on the opposite release surface to the release surface side, and suppress the shedding of particles from the film surface, thereby suppressing the formation defects caused by the deterioration of the planarity on the release surface side.

The following is a detailed description of the implementation form of the present invention. The present invention is a biaxially aligned laminated polyester film having an A layer and a B layer, wherein the A layer contains particles, the maximum peak height (SRp) of the surface roughness of the aforementioned A layer is less than 1.0 μm, and the relationship between the maximum size Dmax and the minimum size Dmin of the particles in the polyester film satisfies the following (Formula 1): 0.5 μm ≦ (Dmax−Dmin) ≦ 5.5 μm                 (Formula 1). The aforementioned biaxially aligned laminated polyester film is used as a release film for forming a resin sheet.

The biaxially aligned laminated polyester film of the present invention is composed of a laminated structure having at least an A layer and a B layer (hereinafter also referred to as a substrate film). For example, a release film can be obtained by having a release layer on one side of the substrate film of the present invention. It is preferred to configure the functional layer on the B layer side of the polyester film, for example, to laminate the release film on the B layer side of the polyester film. In one embodiment, the polyester film may also have an A layer, a C layer (intermediate layer), and a B layer in sequence, and a functional layer (such as a release layer) is laminated on the surface of the B layer.

As the substrate film, for example, there can be listed films composed of polyethylene terephthalate, polybutylene terephthalate, polyethylene 2,6-naphthalate or copolymers of the constituent components of these resins as the main components. Among them, from the viewpoints of mechanical properties, heat resistance, transparency, price, etc., biaxially stretched polyethylene terephthalate films are particularly preferred. Layer A and layer B in the present invention can use different resins as the main components, or the same resin as the main component. When the copolymer is used as the substrate film, as its dicarboxylic acid component, for example, aliphatic dicarboxylic acids such as adipic acid and sebacic acid; aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, and 2,6-naphthalene dicarboxylic acid; polyfunctional carboxylic acids such as trimellitic acid and pyromellitic acid. Furthermore, as diol components, for example, fatty acid diols such as ethylene glycol, diethylene glycol, 1,4-butanediol, propylene glycol, and neopentyl glycol; aromatic diols such as p-xylene glycol; alicyclic diols such as 1,4-cyclohexanedimethanol; and polyethylene glycols with an average molecular weight of 150 to 20,000 can be listed. The weight ratio of the copolymer components of the preferred copolymer is less than 20% by weight. By less than 20% by weight, good film strength, transparency, and heat resistance can be obtained.

The inherent viscosity of the resin particles used for manufacturing the substrate film is preferably in the range of 0.45 dl/g or more and 0.70 dl/g or less. If the inherent viscosity is 0.45 dl/g or more, the tear resistance tends to be improved. On the other hand, if the inherent viscosity is 0.70 dl/g or less, the increase in the filter pressure can be suppressed, and the high-precision filtration described below can be appropriately performed. The inherent viscosity is preferably 0.50 dl/g or more and 0.70 dl/g or less, and more preferably 0.52 dl/g or more and 0.64 dl/g or less.

The thickness of the biaxially aligned laminated polyester film (substrate film) of the present invention is preferably 12 μm to 50 μm, more preferably 15 μm to 38 μm, and more preferably 19 μm to 33 μm. As long as the thickness of the film is 12 μm or more, there is no risk of deformation due to heat during film production or processing steps or molding, so it is preferred. On the other hand, as long as the thickness of the film is 50 μm or less, the amount of film discarded after use will not become extremely large, which reduces the environmental load, so it is preferred.

As for the thickness of each layer, for example, the B layer which can be laminated with a release layer is preferably 5.0 μm or more, and more preferably 10 μm or more. By the thickness of the B layer being in such a range, the smoothness of the B layer can be well maintained. The thickness of the A layer containing particles is a thickness that can maintain the maximum peak height (SRp) of the present invention, for example, 1 μm or more and 10 μm or less.

In one aspect, the surface roughness (SRp) of the A layer is 1.0 μm or less, more preferably 0.6 μm or less, for example, 0.05 μm or less, or 0.01 μm or less. On the other hand, the surface roughness (SRp) of the B layer may be 1 nm or more. For example, it may be 1 nm or more and 0.01 μm or less. By expressing the surface roughness (SRp) of the B layer in such a range, it is possible to prevent the resin sheet such as the ceramic green body from being transferred into a concave shape, and to prevent the ceramic green body from being transferred to the concave shape. shape defects.

In one embodiment, the biaxially aligned laminated polyester film of the present invention has other layers besides the A layer and the B layer, and may also have a laminated structure of more than three layers. For example, the substrate film may have the following laminated structure: the A layer, the C layer (intermediate layer), and the B layer in sequence. In such an embodiment, the C layer as the intermediate layer may also contain particles. However, the particle size of the C layer must be selected within the range that does not damage the surface shape of the B layer. For example, if the C layer contains foreign matter exceeding 20 μm, it will cause the A layer and the B layer to form larger protrusions, so such particles must be removed.

In one embodiment, the layer B of the laminated functional layer (e.g., release layer) does not substantially contain particles with a particle size of 1.0 μm or more. Preferably, the surface layer B does not substantially contain inorganic particles with a particle size of 1.0 μm or more. By the surface layer B not substantially containing inorganic particles with a particle size of 1.0 μm or more, the particle shape in the substrate is prevented from being transferred to the resin sheet to generate defects.

In one embodiment, particles with a particle size of 1 nm or more and less than 1.0 μm may also exist on the surface layer B of the laminated release layer. By containing particles with a particle size of 1 nm or more and less than 1.0 μm (e.g., inorganic particles) in the surface layer B, defects caused by the transfer of particle shapes in the substrate to the resin sheet can be reduced. In addition, in one embodiment, a resin sheet is laminated on the functional layer laminated on the surface layer B.

In one aspect, the surface layer B preferably does not contain particles with a particle size of less than 1.0 μm. This can more effectively prevent the shape of particles in the base material from being transferred to the resin sheet and causing defects.

In one aspect, the polyester film base material is preferably a laminated film having a surface layer B on at least one side, and the surface layer B does not substantially contain inorganic particles. This can more effectively prevent the particle shape in the base material from being transferred to the resin sheet and causing defects.

For example, the surface layer B that does not substantially contain particles having a particle size of less than 1.0 μm preferably does not substantially contain particles having a particle size of 1.0 μm or more.

Here, in the present invention, "substantially does not contain particles" means that, for example, in the case of inorganic particles less than 1.0 μm, when inorganic elements are quantified by fluorescence X-ray analysis, it means 50 ppm or less, preferably 50 ppm or less. Below 10 ppm, preferably below the detection limit. The reason for this is that even if particles are not actively added to the film, contaminants derived from foreign matter, raw material resin, or dirt attached to the production line or equipment in the film manufacturing process may be peeled off and mixed into the film. In addition, "substantially does not contain particles with a particle diameter of 1.0 μm or more" means that particles with a particle diameter of 1.0 μm or more are not actively contained.

The B layer of the laminated release layer is preferably extremely smooth. Desirably, in the B layer, the number of protrusions with a height of 10 nm or more relative to the average height is 5×10 ² /mm ² or less. With such a number of protrusions, the release agent required to form the release layer can be evenly coated including the protrusions, thereby exerting the original release properties of the release agent. Furthermore, when the number of protrusions of the B layer is in the above range, the protrusions on the surface of the release layer can also be reduced, and the resin sheet such as the ceramic green body can be suppressed from being transferred into a concave shape, and the problems caused by the transfer into a concave shape can be suppressed. Shape defects of the concave portion of the ceramic green embryo, etc.

Examples of the types of particles contained in the A layer, the B layer, and the intermediate layer of the base film include inorganic particles such as silicon dioxide, calcium carbonate, kaolin, titanium oxide, and aluminum oxide, but the present invention is not limited to these.

The A layer contains particles, and the maximum peak height (SRp) of the surface roughness of the A layer is 1.0 μm or less, for example, 0.3 μm or more and 1.0 μm or less. Preferably, it is 0.5 micrometer or more and 0.8 micrometer or less. By having such conditions for the maximum peak height (SRp) of the surface roughness of the A layer, the coarse protrusions of the A layer can be suppressed. For example, the formation of pinholes caused by the transfer of the coarse protrusions from the anti-release surface to the release surface side can be suppressed. , furthermore, formation defects caused by deterioration of planarity on the release surface side can be suppressed.

In the biaxially aligned laminated polyester film of the present invention, the relationship between the maximum size Dmax and the minimum size Dmin of the particles in the polyester film satisfies the following (Formula 1): 0.5μm ≦ (Dmax−Dmin) ≦ 5.5μm (Formula 1) In one aspect, when the A layer and/or the intermediate layer (C layer) in the biaxially aligned laminated polyester film of the present invention contains particles, the above-mentioned relationship (Formula 1) can be expressed. For example, when the particles contained in the A layer have the relationship of (Formula 1), the thick protrusions of the A layer can be significantly reduced, particle detachment can be suppressed, and the occurrence of pinholes in resin sheets such as ceramic green embryos can be suppressed. Regarding the C layer, it is also desirable that the relationship between the maximum size Dmax and the minimum size Dmin of the particles in the polyester film satisfies the following (Formula 1): 0.5μm ≦ (Dmax−Dmin) ≦ 5.5μm (Formula 1) Here, Dmax and Dmin in 0.5 ≦ (Dmax−Dmin) ≦ 5.5 are expressed in μm units. In the specification, sometimes only the value of (Dmax−Dmin) is expressed. However, the value of (Dmax−Dmin) is also expressed in μm units. Expressed in μm.

In the A layer, since the particles have the relationship represented by (Formula 1), especially when molding a thin film ceramic green embryo with a thickness of 1 μm or less, the rotation of the coarse protrusions caused by the counter-separation surface (A layer) can be suppressed. Pinholes printed on the release surface side are formed, and further prevent particles from falling off the film. Generally, when the base film is bent during the winding step during film production or when it comes into contact with a conveyor roller, the load on the particles increases and the particles tend to fall off the film easily. Although the explanation should not be limited to a specific theory, the inventor of the present invention found that, for example, because the particles in the A layer have the relationship expressed by (Formula 1), in the state where the film is curved as described above, the particles can be dispersed in the A layer. The load of the particles can be reduced, thereby reducing the shedding of particles. Furthermore, according to the present invention, the dropout of particles can be reduced, the winding property can be improved, and pinholes in ceramic green embryos and the like during winding can be suppressed, and the dropout of particles during unwinding can also be reduced. On the other hand, when the particles in the A layer do not show the relationship shown in (Formula 1), the explanation should not be limited to a specific theory, but when the film bends, the load on the particles in the A layer cannot be dispersed. Therefore, there is a risk of particles slipping off.

Furthermore, the particles in layer A can more significantly exert the above-mentioned effects by satisfying various conditions described in this specification. For example, the average particle size of the particles in layer A and/or the relationship between the maximum size Dmax and the minimum size Dmin of the particles in layer A can satisfy the relationship described below.

In one embodiment, in order to make the particles in layer A have the relationship represented by (Formula 1), it is preferred that the average primary particle size of the particles contained in layer A is less than 3.0 μm, for example, less than 1.4 μm, and more preferably less than 1.0 μm. Furthermore, the average primary particle size of the particles contained in layer A is greater than 0.3 μm, for example, greater than 0.35 μm. It is preferably greater than 0.3 μm to less than 3.0 μm. In addition, the above numerical ranges can also be appropriately combined. By having such an average primary particle size, rolling wrinkles can be suppressed, and the generation of coarse protrusions can be suppressed. As a result, pinhole suppression, good roll-up/roll-out properties, and particle shedding suppression can be achieved in a highly balanced manner. Furthermore, the average primary particle size (μm) in the present invention can be obtained by fully dispersing the particle powder in the ethylene glycol slurry by high-speed stirring, and using a light transmission centrifugal sedimentation particle size distribution measuring machine (manufactured by Shimadzu Corporation; trade name "SRA-CP3 type") to measure the particle size distribution in the obtained slurry. The cumulative 50% in the measurement can also be used as the measurement result (sometimes expressed as D50).

The relationship between the maximum size Dmax and the minimum size Dmin of the particles in the film of the present invention satisfies the following (Formula 1): 0.5μm ≦ (Dmax−Dmin) ≦ 5.5μm (Formula 1) (Dmax−Dmin) may range from 1.0 μm to 5.0 μm, for example, from 1.2 μm to 5.0 μm, or from 1.4 μm to 5.0 μm. By setting the range of (Dmax − Dmin) from 0.5 μm to 5.5 μm, it is possible to reduce the increase in load on particles during the winding step of film production, contact with conveyor rollers, etc. Inhibits particle detachment from the membrane. Furthermore, even when the film of the present invention is stored in a roll form after the film is formed until the release layer is formed, particles can be prevented from slipping. Therefore, it is possible to suppress the detached particles of the A layer from adhering to the surface of the B layer that forms the release layer, and maintain the high smoothness of the B layer even when the base film is stored. By maintaining the high smoothness of the B layer, a smoother release layer can be formed, thereby preventing the occurrence of pinholes in ceramic green embryos, etc. This can prevent particles from falling off when the film is bent (when rolled into a roll shape). For example, it is possible to prevent slipping particles from adhering to a resin sheet such as a ceramic green body, thereby preventing the function of the resin sheet from being impaired. Furthermore, in manufacturing and transportation systems, contamination caused by particles can be reduced.

On the other hand, the average particle diameter (D50), the maximum size Dmax and the minimum size Dmin of the particles in the film in any step until the completion of the film production, for example, mean particles added to the resin composition constituting the film. diameter. Furthermore, it means the particle size of the particles present in the film after the film is formed. For example, the average particle diameter (D50) of the particles present in the surface layer A means the particle diameter of the entire particle including a portion covered with the resin and a portion not covered with the resin.

In one embodiment, when a film containing particles is extended along a single axis or a double axis, when the hole size generated by the peeling between the resin and the particles is set to t, and the average particle size of the particles in the film is set to d, it is preferably satisfied as follows (Formula 2): 0.5 ≦ t/d ≦ 3.0                 (Formula 2) For example, the relationship of t/d is less than 2.8, less than 2.5, or less than 2.4. On the other hand, the relationship of t/d is greater than 1.0, or greater than 1.2. It is preferred that the relationship of t/d is greater than 1.0 and less than 2.8. By making the relationship between the hole size t and the average particle size d of the particles in the film within the above range, the particle shedding during the film winding step and the release process can be suppressed. Furthermore, the film undulations caused by the holes can be formed appropriately, so that the air exclusion property of the film can be well maintained. Since the present invention can show the good air exclusion property of the film, the rolling wrinkles generated when the film is rolled can be suppressed. By removing the film roll, the planarity can be improved, the release layer is formed uniformly, and the pinholes for the ceramic green body can be prevented. In a preferred embodiment, the average particle size d of the particles in the film means the average particle size d of the particles in the A layer. Furthermore, the hole size t generated by the peeling between the resin and the particles means the hole size existing in the film after the film is stretched. In one embodiment, the hole size t existing in the A layer after stretching can be applied. In addition, the A layer after stretching means the layer corresponding to the A layer before stretching. In one embodiment, holes may be generated in the surface layer A having particles. Although it should not be limited to a specific embodiment, the holes generally exist around the particles, and more specifically, the holes exist in a state of surrounding the particles. Furthermore, when the surface layer B does not contain particles, there are substantially no holes in the surface layer B. However, sometimes contamination components, etc., also cause very few holes to be generated in the surface layer B.

As a surface modification of the particles, it is desirable to modify the surface with commonly used polyacrylic acid, silane coupling agent, or the like. The heat-resistant temperature of the surface treatment agent is preferably 250°C or higher as the 2% weight loss temperature, and more preferably 300°C or higher. By setting the heat-resistant temperature of the surface treatment agent to such a condition, the surface treatment agent can be prevented from disappearing during the heat history of melt extrusion, leading to good dispersion and suppressing particle shedding. The drying temperature of the particles containing particles is preferably 130° C. or higher and within 30 hours, and further preferably within 10 hours. The melt extrusion temperature is preferably within +70°C of the melting peak temperature when the resin is heated with a differential scanning calorimeter (DSC; Differential Scanning Calorimeter) at 20°C/min, and more preferably within +50°C.

The hole size ratio of the unstretched film formed at a shear speed of 50 (1/sec) to 4000 (1/sec) in the T-die in the melt extrusion step is 0, and then holes are formed in the stretching step. The hole is observed by, for example, observing the film cross section with an electron microscope. The extension of the film may be longitudinal and then transverse synchronous extension, or may be gradual extension. In the case of gradual extension, the order of extension may be arbitrary, but depending on the size of the device, etc., the order of vertical and horizontal directions is preferable. Among the stretching ratios, the longitudinal ratio is preferably 2.0 times or more and 5.0 times or less, and further preferably 3.0 times or more and 3.8 times or less. The lateral magnification is preferably 3.5 times or more and 5.0 times or less, and more preferably 4.0 times or more and 4.8 times or less. In one aspect, the stretching ratio in the longitudinal direction is lower than the stretching ratio in the transverse direction. Although the mechanism has not been analyzed, by extending under such conditions, it is possible to suppress the tendency of particles to slip.

The content of particles in the outermost layer, such as layer A, is not particularly limited. In order to stabilize the operability during film formation, the content is preferably 8000 ppm or less, and more preferably 6500 ppm or less. Furthermore, the preferred content is 1000 ppm or more, for example 1500 ppm or more. When the particle content of layer A is within this range, winding wrinkles can be reduced. The term "operability" here refers to the removal of foreign matter in the filter and foreign matter attached to the front nozzle (T film head) of the extruder. The present invention can reduce the occurrence of such foreign matter.

As a method of preparing particles in the base film, a combination of known methods can be used. For example, it can be added at any stage of producing polyester, preferably at the esterification stage, or at the stage from the end of the transesterification reaction to the start of the polycondensation reaction, as a slurry dispersed in ethylene glycol or the like. Just add it to carry out the polycondensation reaction. In addition, it can be carried out by the following methods: using a kneading extruder with vents to mix a slurry of particles dispersed in ethylene glycol, water, etc., and the polyester raw material, or using A method of mixing dried particles and polyester raw materials using a kneading extruder.

Among them, the production method of the present invention is preferably to uniformly disperse the aggregated inorganic particles in a monomer liquid that becomes a part of the polyester raw material, and then add the filtered product before, during, or during the esterification reaction. The method is to use the residual part of the polyester raw material after the esterification reaction. According to this method, since the monomer liquid has a low viscosity, it is easy to uniformly disperse the particles and filter the slurry with high precision, and when added to the remaining part of the raw material, the dispersion of the particles is good and it is difficult to New agglomerates are produced. From this point of view, it is particularly preferable to use the remaining portion of the raw material in a low-temperature state before the esterification reaction.

Furthermore, after obtaining polyester containing particles in advance, the number of protrusions on the surface can be further reduced by mixing and extruding the polyester pellets and pellets without particles (master batch method).

In addition, the base film may contain various additives while maintaining the total light transmittance and the number of protrusions within the range specified in the present invention. Examples of additives include antistatic agents, UV (ultraviolet) absorbers, and stabilizers.

If necessary, an antistatic layer or the like may be provided on the surface opposite to the surface having the release layer, that is, on the surface of the A layer opposite to the release layer side.

(Functional layer) The film of the present invention is preferably provided with a functional layer on the surface of layer B opposite to layer A. For example, the functional layer may be a release layer. The functional layer is not particularly limited and may include resins such as polysilicone resins, cyclic olefin resins, non-cyclic olefin resins, fluorine resins, alkyd resins, acrylic resins, melamine resins, and epoxy resins.

The polysilicone compound is a compound having a polysilicone structure in the molecule, and examples thereof include hardened polysilicone, polysilicone graft resin, alkyl-modified and other modified polysilicone resins, and the like. As the reactive hardening polysilicone resin, the reactive hardening polysilicone resin of the addition reaction system, the reactive hardening polysilicone resin of the condensation reaction system, the reactive hardening polysiloxane resin of the ultraviolet or electron beam curing system can be used. wait. Examples of the polysiloxane resin of the addition reaction system include using a platinum catalyst to react polydimethylsiloxane with a vinyl group introduced into the terminal or side chain and hydrogen siloxane. The hardened polysiloxane resin is an addition reaction system. In this case, it is better to use a resin that can be cured at 120°C within 30 seconds because it can be processed at low temperatures. Examples include low-temperature addition curing types (LTC1006L, LTC1056L, LTC300B, LTC303E, LTC310, LTC314, LTC350G, LTC450A, LTC371G, LTC750A, LTC752, LTC755, LTC760A, LTC850, etc.) manufactured by Toray Dow Corning Corporation and thermal UV curing type (LTC851, BY24-510, BY24-561, BY24-562, etc.), solvent addition type (KS-774, KS-882, X62-2825, etc.) manufactured by Shin-Etsu Chemical Co., Ltd., solvent addition + UV curing type (X62 -5040,

Examples of the polysiloxane resin of the condensation reaction system include polydimethylsiloxane having an OH group at the terminal and polydimethylsiloxane having an H group at the terminal using an organotin catalyst. The polysiloxane resin forms a three-dimensional cross-linked structure. Examples of ultraviolet-curable polysilicone resins include: the most basic type of polysilicone resin that utilizes free radical reaction in the same way as normal polysilicone rubber cross-linking; and polysilicone resin that introduces unsaturated groups and is photocured. Oxygen resin; polysiloxane resin that is cross-linked by decomposing onium salts by ultraviolet rays to produce strong acid, thereby cracking the epoxy group and cross-linking; polysiloxane resin that is cross-linked by the reaction of adding thiol to vinyl siloxane Silicone resin, etc. In addition, electron beams may be used instead of the aforementioned ultraviolet rays. Electron beams have stronger energy than ultraviolet rays. Even if an initiator is not used as in the case of ultraviolet curing, the cross-linking reaction caused by free radicals can still be carried out.

Examples of resins used include UV-curable polysiloxane manufactured by Shin-Etsu Chemical Co., Ltd. (X62-7028A/B, , UV curable polysiloxane (TPR6502, TPR6501, TPR6500, UV9300, UV9315, XS56-A2982, UV9430, etc.) manufactured by Momentive Performance Materials, UV curable polysiloxane ( Silcolease UV POLY200, POLY215, POLY201, KF-UV265AM, etc.).

As the above-mentioned ultraviolet curable polysiloxane resin, acrylate-modified or glycidyloxy-modified polydimethylsiloxane, etc. can also be used. These modified polydimethylsiloxanes can also be used by mixing them with multifunctional acrylate resins or epoxy resins in the presence of a initiator.

Cyclic olefin resins contain cyclic olefins as polymerizable components. Cyclic olefins are polymerizable cyclic olefins having ethylenic double bonds in the ring, and can be classified into monocyclic olefins, bicyclic olefins, tricyclic or higher polycyclic olefins, and the like.

Examples of monocyclic olefins include cyclic C4 to C12 cyclic olefins such as cyclobutene, cyclopentene, cycloheptene, and cyclooctene. Examples of bicyclic olefins include: 2-norbornene; 5-methyl-2-norbornene, 5,5-dimethyl-2-norbornene, and 5-ethyl-2-norbornene. Alkenes, 5-butyl-2-norbornene and other norbornenes with alkyl groups (C1 to C4 alkyl); 5-ethylidene-2-norbornene and other norbornenes with alkenyl groups; 5-Methoxycarbonyl-2-norbornene, 5-methyl-5-methoxycarbonyl-2-norbornene and other norbornenes with alkoxycarbonyl groups; 5-cyano-2-norbornene Norbornenes with cyano groups such as bornene; 5-phenyl-2-norbornene, 5-phenyl-5-methyl-2-norbornene and other norbornenes with aryl groups; octahydrogen Naphthalene (octalin); 6-ethyl-octahydronaphthalene and other octahydronaphthalenes with alkyl groups, etc. Examples of polycyclic olefins include: dicyclopentadiene; 2,3-dihydrodicyclopentadiene, methyl-octahydronaphthalene, dimethyl-octahydronaphthalene, dimethyl-cyclopentadiene naphthalene, Derivatives such as methyl-octahydronaphthalene; 6-ethyl-octahydronaphthalene and other derivatives with substituents; adducts of cyclopentadiene and tetrahydroindene, trimerization of cyclopentadiene to tetrapolymers, etc.

Acyclic olefin resins contain acyclic olefins as polymerization components. Examples of acyclic olefins include ethylene, propylene, 1-butene, isobutylene, 1-pentene, 2-methyl-1-butene, 3-methyl-1-butene, 1-hexene, 3-methyl-1-pentene, 4-methyl-1-pentene, 1-heptene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene, and the like. Rubber can also be used as a surface treatment resin. For example, copolymers of butadiene, isoprene, and the like can be cited. Regardless of whether it is a cyclic olefin or acyclic olefin, the olefin resin can be used alone or two or more can be copolymerized. Cyclic olefin resins and non-cyclic olefin resins may also partially have hydroxyl-modified or acid-modified sites, and these functional groups are crosslinked using a crosslinking agent. The crosslinking agent can be appropriately selected according to the modified group. For example, in addition to aromatic diisocyanates such as toluene diisocyanate, 2,4-toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, xylene diisocyanate, polymethylene polyphenyl isocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, etc., lower aliphatic diisocyanates such as diisocyanates can be used. In addition to isocyanate-based crosslinking agents such as cyanate esters, cyclopentyl diisocyanate, cyclohexyl diisocyanate, isophorone diisocyanate, hydrogenated products of the aforementioned aromatic diisocyanates, and other alicyclic isocyanates, melamine-based crosslinking agents such as methyl etherified melamine resin and butyl etherified melamine resin, and epoxy-based crosslinking agents can also be listed.

The fluorine-based compound is not particularly limited as long as it has at least one of a perfluoroalkyl group and a perfluoroalkyl ether group. Fluorine compounds can also be partially denatured by acids, hydroxyl groups, acrylate groups, etc. Cross-linking agents can also be added and cross-linked through denatured sites. Alternatively, a compound having at least one of a perfluoroalkyl group and a perfluoroalkyl ether group may be added to the UV curable resin and polymerized. Alternatively, a compound having a perfluoroalkyl group that does not have a reactive functional group may be used in the form of being added to the binder resin in a small amount.

Release agents such as polyolefin-based release agents, long-chain alkyl-containing resin-based release agents, fluorine-based release agents, and polysilicone-based release agents can be used as the main resin of the release layer of the release film, or can also be used as an additive for the adhesive resin. The adhesive resin is not particularly limited, and for example, a UV-curing resin obtained by curing the functional groups such as acrylic or vinyl, epoxy, etc. by UV irradiation; or a thermoplastic resin such as an ester-based, urethane-based, olefin-based, acrylic-based, etc.; or a thermosetting resin such as an epoxy-based, melamine-based, etc.

(resin sheet) Especially when the functional layer is used as a release layer, the object to be released can be layered on the surface of the release layer. For example, an object to be released includes a resin sheet. In one aspect, the release film of the present invention is not particularly limited as long as it is a resin sheet, and it can also be applied to the production of adhesives and optical films. In one aspect, it is a release film for resin sheet molding containing an inorganic compound. Examples of inorganic particles include metal particles, metal oxides, minerals, and the like, and examples include calcium carbonate, silica particles, alumina particles, and barium titanate particles. Examples of the resin include polyvinyl acetal resin, poly(meth)acrylate resin, and the like. The present invention can have a release layer with high smoothness. Even if the resin sheet contains these inorganic compounds, it can suppress defects that may be caused by the inorganic compounds. For example, it can suppress the damage of the resin sheet and the resin sheet becoming difficult to follow. The problem of peeling off the release layer. The resin component forming the resin sheet can be appropriately selected depending on the intended use. In one aspect, the resin sheet containing the inorganic compound is a ceramic green body, an antistatic laminated body or an antistatic sheet, a solid state battery laminated body or a solid state battery sheet, a film capacitor laminated body or a film capacitor sheet, etc. . In other aspects, the resin sheet can also be a printing layer, a protective layer, an adhesive layer, or a layer with gaps. For example, the ceramic green body can contain barium titanate as the inorganic compound. In one aspect, the thickness of the resin sheet is 0.2 μm or more and 1.0 μm or less. [Example]

The present invention is described based on the following examples, but the present invention is not limited to these examples. The method for measuring the characteristic values and the method for evaluating the efficacy in the present invention are as follows.

(1) Particle size and distribution range in the film The surface of the particle-containing layer (layer A) was subjected to plasma treatment for about 3 hours using a plasma reactor device manufactured by Yamato Corporation at an output of 50W. Then, the film was metal-evaporated, and the particles not covered by the resin component were photographed from the surface of layer A at 1500 times × 10 shots using a scanning electron microscope (SEM), and the long side of the particles was measured to obtain the particle size. 20 particles were measured each time, and the particle size distribution was calculated. Based on the results obtained, the maximum size Dmax and minimum size Dmin of the particles in the polyester film were derived.

(2) Average hole ratio The particle size d observed in the above (1) and the long side t of the void (hole size) around the particle were measured. The obtained ratio of particle size to hole size (t/d) was used as the hole size.

(3) Surface roughness [Measurement method of the number of coarse protrusions SPc (4000)] 1. Use a high-precision micro-shape measuring instrument (3D surface roughness meter) using the stylus method to measure the surface morphology in accordance with JIS-B0601 (1994) using the following conditions. Measuring device: 3D micro-shape measuring instrument (Model ET4000A); manufactured by Kosaka Laboratory Co., Ltd. Analytical device: 3D surface roughness analysis system (Model TDA-31). Stylus: Tip diameter 2 μm; made of diamond. Needle pressure: 300 μN. Measuring direction: Measure once in the film length direction and once in the film width direction and then average. X measuring length: 1250 μm. X conveying speed: 0.1 mm/s (measuring speed). Y measuring length: 300 μm. Y transmission distance: 2μm (measurement interval). Y line number: 151 (measurement line number). Z magnification: 20000 times. Low-pass cutoff: 0.25mm (ripple cutoff value). High-pass cutoff: R+Wmm (roughness cutoff value). (R+W means no cutoff). Filter type: Gaussian spatial type Leveling: Yes (slope correction). Reference area: ^1mm2 .

(4) Particle shedding property: The surface of the particle-containing layer of the film was observed with a scanning electron microscope (SEM) at 600 times, and the number of particles falling off per 15 mm ² was counted. Particle detachment is the number of voids visible from the film surface (≒the number of particles that have detached), and is evaluated based on the following criteria. 〇: Less than 20. △: Less than 50. ×: 50 or more.

(5) Rolling pleats For each product, the number of visible convex wrinkles formed by the intrusion of air from the surface of a roll with a thickness of 18 μm to 50 μm, a width of 200 mm to 3000 mm, and a length of 4000 m to 12000 m was evaluated using the following reference values. 〇: 0 to less than 10 roots. △: 11 to 20 or less. ×: 21 or more.

(6) Pinhole evaluation A solvent (toluene), a ceramic raw material (BaTiO ₃ ; manufactured by Fuji Titanium), a binder, a plasticizer, etc. are mixed to form a paste, which is then dispersed using a ball mill to obtain a ceramic slurry. The surface of the release layer of the release film is coated with the above-mentioned ceramic in a manner such that the thickness becomes 1 μm when dry using a doctor blade method, and dried in an oven at an atmosphere temperature of 100°C for 5 minutes to obtain a ceramic green body. The sheet is illuminated from the opposite side to an area of 10 ^cm2 of the sheet, the occurrence of pinholes is observed, and evaluation is performed using the following criteria. In addition, a release layer is laminated on layer B. The main components contained in the release layer are as described in Example 1 described later. ×: There are multiple pinholes. △: Almost no pinholes. ○: No pinholes.

(Example 1) (Preparation of polyethylene terephthalate masterbatch particles (a) containing calcium carbonate particles) Measured using a light transmission type particle size distribution measuring device (manufactured by Shimadzu Corporation; SA-CP3) Calcium carbonate particles (manufactured by Maruo Calcium Co., Ltd.) with an average particle diameter of 0.6 μm are placed in ethylene glycol and filtered using a filter made of viscose rayon with a 95% cutoff diameter of 30 μm to obtain calcium carbonate particles. of ethylene glycol slurry. Polyethylene terephthalate masterbatch particles (a) containing calcium carbonate particles were obtained by the following method. The temperature of the esterification reaction tank was raised, and when it reached 200°C, a slurry consisting of 86.4 parts by weight of terephthalic acid and 64.4 parts by weight of ethylene glycol was put in, and 0.03 of antimony trioxide as a catalyst was added while stirring. parts by weight and 0.088 parts by weight of magnesium acetate tetrahydrate and 0.16 parts by weight of triethylamine. Then, the pressure was increased and the temperature was increased, and a pressure esterification reaction was performed under the conditions of gauge pressure (gauge pressure) 3.5 kgf/cm ² and 240°C. Then, the pressure in the esterification reaction tank was returned to normal, and 0.040 parts by weight of trimethyl phosphate was added. Furthermore, the temperature was raised to 260° C., and 15 minutes after adding trimethyl phosphate, the ethylene glycol slurry of the calcium carbonate particles was added so that the content of the resulting polyester would be 20,000 ppm. After 15 minutes, the obtained esterification reaction product was transferred to a polycondensation reaction tank, and a polycondensation reaction was performed under reduced pressure at 280°C. After the polycondensation reaction is completed, a NASLON filter with a 95% cutoff diameter of 28 μm (manufactured by Nippon Seisen Co., Ltd.) is used for filtration to obtain polyterephthalate containing calcium carbonate particles with an intrinsic viscosity of 0.62 dl/g. Ethylene formate masterbatch particles (a).

(Preparation of polyethylene terephthalate particles (b)) As the esterification reaction device, a continuous esterification reaction device composed of a three-stage complete mixing tank with a stirring device, a fractionator, a raw material inlet and a product outlet is used to convert TPA (terephthalic acid; terephthalic acid) Let it be 2 tons/hour, set EG (ethylene glycol; ethylene glycol) to 2 moles per mole of TPA, and set it to 2 moles per mole of PET (polyethylene terephthalate; polyethylene terephthalate) produced. The amount of Sb atoms in antimony trioxide was set to 160 ppm, and the slurry of these components was continuously supplied to the first esterification reaction tank of the esterification reaction device, and reacted under normal pressure with an average residence time of 4 hours and 255°C. . Then, the reaction product in the first esterification reaction tank is continuously taken out of the system and supplied to the second esterification reaction tank. In the second esterification reaction tank, the reaction product relative to the generated polymer ( The produced PET) was 8% by weight of the EG distilled from the first esterification reaction tank, and an EG solution containing magnesium acetate in an amount of 65 ppm containing Mg atoms was added to the produced PET, and to the produced PET To PET, an EG solution of TMPA (trimethyl phosphate; trimethyl phosphate) containing P atoms in an amount of 20 ppm was added, and the reaction was carried out under normal pressure with an average residence time of 1.5 hours and 260°C. Next, the reaction product in the second esterification reaction tank was continuously taken out of the system and supplied to the third esterification reaction tank, and TMPA containing P atoms in an amount of 20 ppm was added to the produced PET. The EG solution was reacted under normal pressure with an average residence time of 0.5 hours and 260°C. The esterification reaction product generated in the third esterification reaction tank is continuously supplied to the three-stage continuous polycondensation reaction device to perform polycondensation, and a filter material of stainless steel sintered body (nominal filtration accuracy of 5 μm particle cutoff 90% ) is filtered to obtain polyethylene terephthalate particles (b) with an ultimate viscosity of 0.620dl/g.

(Manufacturing of polyester film) The polyethylene terephthalate masterbatch particles (a) are diluted at a predetermined ratio using polyethylene terephthalate particles (b) containing no particles, dried under reduced pressure (3 Torr) at 180°C for 8 hours, and then supplied to extruder 1. The polyethylene terephthalate particles (b) containing no particles are supplied to extruder 2, and the intermediate layer is supplied to extruder 3 and melted at 285°C. The three polymers were filtered using a stainless steel sintered body filter material (nominal filter accuracy 95% cutoff for 10μm particles), laminated using a three-layer confluence module with a rectangular lamination section, extruded from a nozzle into a sheet, and then cast using an electrostatic application method. The sheet was rolled up onto a casting drum with a surface temperature of 30°C and cooled to solidify, thereby forming an unstretched film. The unstretched film was stretched to 3.3 times in the longitudinal direction at 85°C, and then stretched 4.0 times in the width direction using a tenter, and heat-treated at 230°C for 5 seconds to obtain a laminated film with a total thickness of 31 μm, in which the ratio of the layer (A) containing calcium carbonate particles was 20%, the ratio of the layer (B layer) containing no particles substantially was 40%, and the ratio of the intermediate layer was 40%. The particle content of the layer (A) containing calcium carbonate particles was 5000 ppm. Next, an ultraviolet cation-curing polysilicone resin (manufactured by Toshiba Silicone Co., Ltd.; UV9315) was dispersed in a solvent (n-hexane) so that the resin solid concentration became 2 wt %, and 1 part by weight of bis(alkylphenyl)iodonium hexafluoroantimonate was added as a curing catalyst to 100 parts by weight of the polysilicone resin to prepare a coating liquid containing the polysilicone resin. The coating liquid containing the silicone resin was applied to the surface of layer B of the laminate film using a wire bar, dried at 100°C for 30 seconds, and then irradiated with ultraviolet light (300 mj/cm ² ) using an ultraviolet irradiation device to obtain a ceramic release polyester film (the amount of the silicone release layer after drying was 0.10 g/m ² ). The evaluation results are shown in Tables 1 and 2.

The particles in the film obtained in Example 1 showed a relationship of 0.5 ≦ (Dmax−Dmin) ≦ 5.5.

(Example 2) A biaxially stretched polyester film was produced in the same manner as in Example 1 except that the average particle diameter of the particles contained in PET was changed to 0.9 μm. The particles in the film obtained in Example 2 showed a relationship of 0.5 ≦ (Dmax−Dmin) ≦ 5.5.

(Example 3) A biaxially stretched polyester film was produced by the same method as Example 1 except that the film thickness was changed to 25 μm using the same composition as Example 2.

(Example 4) A biaxially stretched polyester film was produced by the same method as Example 1 except that the film thickness was changed to 19 μm using the same composition as Example 2.

(Example 5) A biaxially stretched polyester film was prepared in the same manner as in Example 1 except that the average particle size of the particles contained in PET was changed to 1.2 μm. The distribution of the particle size obtained in Example 5 was from 0.3 μm to 6.0 μm.

(Example 6) A biaxially stretched polyester film was produced by the same method as Example 1 and Example 2 except that the particle addition amount in Example 2 was changed to 3000 ppm.

(Example 7) A biaxially stretched polyester film was prepared by the same method as in Examples 1 and 2 except that the particle addition amount in Example 2 was changed to 8000 ppm.

(Example 8) A biaxially stretched polyester film was prepared in the same manner as in Example 2 except that the intermediate layer contained 400 ppm of calcium carbonate having an average particle size of 0.9 μm.

(Comparative example 1) A biaxially stretched polyester film was produced in the same manner as in Example 1 except that the average particle diameter of the calcium carbonate particles was changed to 0.2 μm. The particles in the obtained film did not show the relationship 0.5 ≦ (Dmax−Dmin) ≦ 5.5.

(Comparative Example 2) A biaxially stretched polyester film was prepared in the same manner as in Example 1 except that the average particle size of the calcium carbonate particles was changed to 1.5 μm. The particles in the obtained film did not show the relationship of 0.5 ≦ (Dmax−Dmin) ≦ 5.5.

(Comparative example 3) A biaxially stretched polyester film was produced in the same manner as in Example 1 except that the average particle diameter of the calcium carbonate particles was changed to 2.0 μm. The particles in the obtained film did not show the relationship 0.5 ≦ (Dmax−Dmin) ≦ 5.5.

(Reference Example 4) (Preparation of polyethylene terephthalate particles containing silica particles) In the same manufacturing method as in Example 8, silica particles with a silica concentration of 5% were obtained using only 1.0 μm silica (manufactured by Nippon Catalyst Co., Ltd.). Furthermore, a biaxially stretched polyester film was prepared using the same film-making method as in Example 1. In addition, in Reference Example 4, the distribution of the particle size contained in the film was extremely small, and the distribution of the particle size was actually concentrated near the average particle size. Reference Example 4 showed a tendency for particles to slide off.

(Reference Example 5) (Preparation of polyethylene terephthalate particles containing silica particles) In the same manufacturing method as in Example 8, silica-containing particles with a silica concentration of 5% were obtained using only 1.2 μm silicon dioxide (manufactured by Nippon Shokubai Co., Ltd.). Furthermore, a biaxially stretched polyester film was produced using the same film production method as in Example 1. Furthermore, in Reference Example 5, the particle size distribution contained in the film was extremely small, and the particle size distribution was substantially concentrated around the average particle diameter. Reference Example 5 showed a tendency for particles to slip.

[Table 1]

[Table 2] Extension ratio Thickness after extension In the membrane Average hole ratio Thick protrusions Particle shedding Curl pleats Ceramic pinhole Particle size distribution range (Formula 1) (Dmax - Dmin) Vertical Horizontal μm μm Embodiment 1 3.4 4.5 31 4.5 2.2 ○ ○ ○ ○ Embodiment 2 3.4 4.5 31 4.5 2.2 ○ ○ ○ ○ Embodiment 3 3.4 4.5 25 4.5 2.2 ○ ○ ○ ○ Embodiment 4 3.4 4.5 19 4.5 2.2 ○ ○ ○ ○ Embodiment 5 3.4 4.5 31 4.5 2.2 ○ ○ ○ ○ Embodiment 6 3.4 4.5 31 4.5 2.2 ○ ○ ○ ○ Embodiment 7 3.4 4.5 31 4.5 2.2 ○ ○ ○ ○ Embodiment 8 3.4 4.5 31 4.5 2.2 ○ ○ ○ ○ Comparison Example 1 3.4 4.5 31 4.5 1.9 ○ ○ × △ Comparison Example 2 3.4 4.5 31 6.0 2.5 × ○ ○ × Comparison Example 3 3.4 4.5 31 6.0 2.7 × ○ ○ × Reference Example 4 3.4 4.5 31 0.4 2.3 ○ △ ○ △ Reference Example 5 3.4 4.5 31 0.4 2.3 ○ △ ○ △

The particle size distribution of Comparative Examples 1 to 3 includes less than 0.3 μm and/or more than 6.0 μm, and it is impossible to suppress the rolling wrinkles and pinholes. On the other hand, in the present invention, for example, coarse protrusions can be suppressed, rolling wrinkles can be suppressed, pinhole formation caused by the transfer of coarse protrusions on the opposite release surface to the release surface side can be suppressed, and particles can be suppressed from falling off the film surface, and further formation defects caused by deterioration of the planarity of the release surface side can be suppressed. [Industrial Applicability]

The present invention provides a biaxially aligned laminated polyester film, which can more effectively suppress the generation of pinholes in the manufacturing step of a resin sheet of a ceramic green sheet, etc., compared with the prior art.

Claims (5)

A biaxially aligned laminated polyester film has an A layer and a B layer; the A layer contains particles; the maximum peak height (SRp) of the surface roughness of the A layer is less than 1.0 μm; the relationship between the maximum size Dmax and the minimum size Dmin of the particles in the polyester film satisfies the following (Formula 1): 0.5 μm ≦ (Dmax−Dmin) ≦ 5.5 μm (Formula 1) The biaxially aligned laminated polyester film is used as a release film for forming a resin sheet. The biaxially aligned laminated polyester film as described in claim 1, wherein The aforementioned B layer substantially does not contain particles with a particle size of 1.0 μm or more; The maximum peak height (SRp) of the surface of the B layer is 1.0 μm or less. The biaxially aligned laminated polyester film as described in Claim 1, wherein the ratio of the hole size t in the film to the average particle size d of the particles satisfies the following (Formula 2): 0.5 ≦ t/d ≦ 3.0 (Equation 2). The biaxially aligned laminated polyester film according to claim 1 has a film thickness of 12 μm or more and 50 μm or less. A release film comprises: A biaxially aligned multilayer polyester film as described in any one of claims 1 to 4; and A functional layer; The functional layer is disposed on the side of the aforementioned layer B of the aforementioned biaxially aligned multilayer polyester film.