CN107073916A - Double axial orientated polyester film - Google Patents

Abstract

The present invention provides a kind of biaxially oriented polyester film, and described biaxially oriented polyester film is suitable for use as support film, and when described support film transfers transfer film such as electromagnetic wave shielding film to components such as FPC or module, A good matte appearance can be imparted to the surface, and the support film after transfer is excellent in peelability. That is, the present invention can be realized by a biaxially oriented polyester film which is a laminated polyester film having a substrate layer and a particle-containing mat layer, wherein the center of the mat layer surface is The line average roughness is 400-1000 nm, the ten-point average roughness is 4000-8000 nm, the surface gloss (G ₆₀ ) is 6-20, and the porosity of the protrusions on the surface is 20% or less.

Description

biaxially oriented polyester film

technical field

The present invention relates to a biaxially oriented polyester film particularly suitable for use as a support film used when transferring an electromagnetic wave shielding film to a flexible printed circuit, a module, or the like. More specifically, it relates to a matte biaxially oriented polyester film which, while carrying out the above-mentioned transfer, also transfers the concave and convex shape of the surface of the support film, and is suitable for applying to the surface of the electromagnetic wave shielding film. Gives a matte finish.

Background technique

Conventionally, in electronic equipment including office equipment such as personal computers, communication equipment such as mobile phones, medical equipment, and various equipment incorporating the above equipment, in order to absorb electromagnetic waves generated from the near field and suppress malfunctions, contact It is known to use an electromagnetic wave shielding film to cover obstacles such as false contact and noise. film), and press it to the surface of various equipment at high temperature to transfer the electromagnetic wave shielding film. (eg, Patent Documents 1, 2)

In addition, conventional transfer-type electromagnetic wave shielding films have used a flat support film in order to obtain a clear (clear) finished product appearance, but in recent years, attempts have been made to use a The transfer method is applied. Accordingly, there has been a demand for a support film having a matte layer and excellent transferability of a matte appearance.

On the other hand, regarding a film having a mat layer, Patent Document 3 discloses a mat laminated polyester film for molding that is excellent in moldability, thickness unevenness, and heat resistance. However, studies have not been carried out as a support film for transfer of an electromagnetic wave shielding film, etc. Therefore, even if it is sufficient for general molding processing, it is not sufficient as a support film for transfer.

In addition, Patent Document 4 discloses a biaxially stretched co-extruded matte polyester film with good mattness and transparency, and discloses adding 1 to 10% by weight of particles with a particle size of 2 Particles of ~5 μm. However, the glossiness (G ₆₀ ) of the specifically exemplified film is about 50 to 70, and there is no research on its use as a support film for transfer processing;

Patent Document 1: Japanese Patent Laid-Open No. 2004-95566

Patent Document 2: Japanese Patent Laid-Open No. 2009-38278

Patent Document 3: Japanese Patent Application Laid-Open No. 4-110147

Patent Document 4: Japanese Unexamined Patent Publication No. 2002-200723.

Contents of the invention

The problem to be solved by the invention

In recent years, when transferring an electromagnetic wave shielding film to a flexible printed circuit (FPC) or module, transfer processing at higher temperatures and higher speeds has gradually been carried out in order to improve production efficiency. However, under such transfer conditions, in the conventional support film as described above, if the film glossiness is lowered, a problem of peelability such as breakage of the support film at the time of peeling tends to arise. In addition, when the support film is colored white in order to improve the visibility (visibility) of the support film, the base film will be broken more easily.

The present invention has been accomplished in view of the above circumstances, and its object is to provide a kind of biaxially oriented polyester film, which is particularly suitable as a support film for electromagnetic wave shielding film transfer, and for the support film for electromagnetic wave shielding film transfer In other words, when the electromagnetic wave shielding film is transferred to members such as FPC and modules, it can give the surface a better matte appearance than before, and even if the support film is peeled off after the transfer, it is less likely to cause problems such as breakage. Furthermore, it is preferable to provide a biaxially-oriented polyester film with favorable visibility.

means to solve the problem

The inventors of the present invention conducted intensive studies to solve the above-mentioned problems. As a result, they found that when imparting a matte appearance to an electromagnetic wave shielding film by a transfer method, in order to impart a matte appearance that is more matte than conventional When the particle size is increased or the particle content is increased, there will be problems with the peelability of the support film after transfer, and this problem can be improved by suppressing the exposure of the particles used in the mat layer on the surface of the film mat layer. Further studies have been repeated, and the results The present invention has been accomplished.

Like this, through the present invention, can provide following scheme:

"1. A biaxially oriented polyester film, which is a laminated polyester film having a substrate layer and a matting layer containing particles on at least one surface, wherein the centerline average roughness (center line average roughness) of the matting layer surface is -line averageroughness) (Ra) is 400-1000nm, ten-point average roughness (Rz) is 4000-8000nm, the surface gloss (G ₆₀ ) is 6-20, and the porosity of the protrusions on the surface (ボイドbreakage rate) is below 20%;

2. The biaxially oriented polyester film according to the above 1, wherein the hue L value of the substrate layer is 60 to 80;

3. The biaxially oriented polyester film according to the above-mentioned 1 or 2, wherein the apparent (see かけ) surface energy of the surface of the matting layer is 60 dyn/cm or less;

4. The biaxially oriented polyester film according to any one of the above 1 to 3, wherein the polyester constituting the mat layer is mainly composed of polyethylene terephthalate and contains polyethylene terephthalate selected from polyethylene terephthalate. At least one of propylene glycol diformate, polybutylene terephthalate, and polycyclohexylene dimethyl terephthalate (polycyclohexylene dimethylene terephthalate);

5. The biaxially oriented polyester film according to any one of the above 1 to 4, wherein the average particle diameter of the particles in the matte layer is 2.5 to 5.5 μm, and the content is 5 to 18% by mass;

6. The biaxially oriented polyester film according to any one of the above 1 to 5, wherein the particles in the matting layer are amorphous silica or synthetic zeolite;

7. The biaxially oriented polyester film according to any one of the above 1 to 6, wherein the main component of the polyester constituting the substrate layer is polyethylene terephthalate;

8. The biaxially oriented polyester film according to the above 7, wherein the polyester constituting the substrate layer has an intrinsic viscosity of 0.56 to 0.70 dl/g;

9. The biaxially oriented polyester film according to any one of the above 1 to 8, wherein, based on the mass of the substrate layer, the particle content of the substrate layer is 3.0% by mass or less;

10. The biaxially oriented polyester film according to any one of 1 to 9 above, which is used as a support film for transferring an electromagnetic wave shielding film. ".

The effect of the invention

According to the present invention, it is possible to provide a biaxially oriented polyester film in which good matt can be imparted to the member surface when transferring a transfer film such as an electromagnetic wave shielding film formed on the surface of the mat layer to a member such as an FPC or a module In addition, when the support film is peeled off after transfer, the peelability such as breakage is less likely to decrease. Furthermore, it is preferable to provide a biaxially oriented polyester film with good visibility.

detailed description

Hereinafter, the present invention will be described in detail.

＜Biaxially oriented polyester film＞

The biaxially oriented polyester of the present invention is a laminated polyester film having a substrate layer and a particle-containing mat layer on at least one surface. By having a mat layer and a substrate layer, the surface roughness and glossiness described later can be obtained with stable film forming properties. If there is no substrate layer and only a single layer containing particles is used, it will be difficult to satisfy both surface roughness and glossiness and stable film forming properties.

(matting layer)

The mat layer occupying at least one surface of the laminated polyester film is formed of polyester containing particles (concavity-convex-forming particles) for forming concavo-convex on the surface, and the porosity of protruding from the surface described later is 20% or less In view of this, a copolyester containing particles having good stretchability, and a polyester composition obtained by melt-blending a plurality of polyesters are preferable, and it is particularly preferable that the main component is the same as the polyester used in the base material layer described later. By. That is, for example, when the main component of the polyester in the substrate layer is ethylene terephthalate, the polyester in the matte layer is preferably a polyethylene terephthalate-based copolyester, or polyethylene terephthalate-based copolyester. Polyester composition mainly composed of ethylene glycol ester. Among these, at least one selected from the group consisting of polytrimethylene terephthalate, polybutylene terephthalate, and polycyclohexanedimethylene terephthalate is preferable as the subcomponent of the polyester composition.

In addition, the average particle diameter of the particles in the mat layer is preferably 2.5 to 5.5 μm, and the content thereof is preferably 5 to 18% by mass based on the mass of the mat layer. In addition, it is preferable that the maximum particle diameter of the particles contained in the mat layer is 16 μm or less. By adopting such a state, not only a sufficient matte appearance can be obtained, but also it is easy to make the releasability excellent in the transfer process.

When the particle content in the matte layer is less than the lower limit, it tends to be difficult to obtain the above-mentioned glossiness. On the other hand, when it exceeds the upper limit, not only the effect of improving peelability after high-temperature pressure bonding in the transfer process is reduced There is a tendency that the film forming property is lowered, and breakage is likely to occur, etc., and there is a tendency that the production of the film itself becomes difficult. From the above viewpoint, the particle content is preferably 7% by mass or more, more preferably 10% by mass or more, and preferably 16% by mass or less, more preferably 14% by mass or less.

The average particle diameter of the particles is more preferably 3.0 to 5.5 μm, more preferably 3.0 to 5.3 μm. When the average particle size of the particles is less than the lower limit, the effect of reducing the glossiness tends to be reduced, and the addition amount of the particles is further increased in order to reduce the glossiness, which tends to reduce the effect of improving the releasability in the transfer process. On the other hand, when the average particle diameter of the particles exceeds the upper limit, not only the peelability improving effect tends to decrease, but also the film forming property of the film tends to be poor.

In addition, the maximum particle size of the particles is preferably 15 μm or less, more preferably 12 μm or less. It should be noted that the maximum particle size here refers to the particle size (d ₉₈ ) at 98% of the cumulative particle size distribution curve.

For the particles used in the mat layer, the weight change at 300° C. by the TG-DTA method is preferably 3.0% or less, more preferably 1.5 to 3.0%. It should be noted that the weight change of the particles here specifically refers to the measurement of the weight change at 300°C when the temperature is raised from 30°C to 500°C at a heating rate of 10°C/min using a TG-DTA device. value. When this weight change exceeds the upper limit, foaming is caused in the production process of the polyester film and the transfer process of the electromagnetic wave shielding film, or the molecular weight is reduced to reduce the film forming property or heat resistance of the film. When the particles are contained, the film-forming properties and heat resistance of the film may be remarkably lowered.

The type of particles may be either inorganic particles or organic particles, and examples thereof include amorphous silica (colloidal silica), silicon dioxide, talc, calcium carbonate, magnesium carbonate, barium carbonate, calcium sulfate, barium sulfate, Lithium phosphate, calcium phosphate, magnesium phosphate, alumina, carbon black, titanium dioxide, kaolin, synthetic zeolite, cross-linked polystyrene particles, cross-linked acrylate particles, etc. Among these particles, amorphous silica or synthetic zeolite is preferable, and any one of them may be used, or they may be used in combination. In addition, a mixture of particles of the same kind but with different particle diameters can also be used. In addition, in the case of amorphous silica, it is more preferable that the surface is treated with a silane coupling agent to reduce the moisture adsorption.

Particularly preferred particles are synthetic zeolites. In order to reduce the adsorption properties of synthetic zeolites, especially the moisture adsorption properties, synthetic zeolites are preferably treated with an acid having a pH of 5 or higher to such an extent that the shape of the particles is not destroyed. Synthetic zeolite that has been heat-treated above the temperature.

The shape of the particles is not particularly limited, but if the particle is amorphous, the particle size distribution becomes wider, coarse protrusions due to aggregation are likely to occur, and the effect of improving peelability may be reduced, or the film forming property of the film may be reduced. Therefore, the particle shape is preferably spherical or polyhedral. Preferable particles may, for example, be spherical or faceted synthetic zeolites. Especially in the case of polyhedral particles, it is easy to obtain a matting effect. Among polyhedral particles, cubic particles are particularly preferred.

The method of adding these particles is not particularly limited, for example, a method of adding in the form of a glycol dispersion during polycondensation of polyester; a method of adding to a mat layer via a masterbatch during extrusion; and the like.

The thickness of the mat layer is suitably in the range of 3 to 10 μm, preferably 4 to 9 μm in the case of a two-layer structure, and suitably in the range of 2 to 5 μm in the case of a three-layer structure.

(substrate layer)

The polyester constituting the base layer of the present invention is a linear saturated polyester synthesized from an aromatic dibasic acid or an ester-forming derivative thereof and a diol or an ester-forming derivative thereof. Specific examples of the polyester include polyethylene terephthalate, polybutylene terephthalate, polycyclohexanedimethylene terephthalate, poly-2,6-naphthalene di Ethylene glycol formate and the like may be a copolymer in which a small amount of secondary components are copolymerized or a blend with other resins in a small proportion. Among these, polyethylene terephthalate and polyethylene-2,6-naphthalate are preferable from the viewpoint of heat resistance, and polyethylene terephthalate is The balance between property and moldability is good, so it is particularly preferable.

The particle content of the base material layer is preferably 3.0% by mass or less, more preferably 2.5% by mass or less, and still more preferably 2.0% by mass or less, based on the mass of the base material layer. By being in such a state, excellent film-forming properties are easily obtained.

The type of particles used in the substrate layer is not particularly limited as long as they are particles that can usually be added to a film, and inorganic particles and organic particles may be used. Specifically, amorphous silica (colloidal silica), silica, talc, calcium carbonate, magnesium carbonate, barium carbonate, calcium sulfate, barium sulfate, lithium phosphate, calcium phosphate, magnesium phosphate, oxide Aluminum, carbon black, titanium dioxide, kaolin, synthetic zeolite, cross-linked polystyrene particles, cross-linked acrylate particles, etc. Among these particles, one kind or two or more different kinds of particles may be contained, and a mixture of the same kind of particles having different particle diameters may also be used. Among these particles, in order to improve visibility, it is preferable to contain 0.5% by mass to 2.0% by mass of titanium dioxide. When it is less than the above range, visibility may deteriorate, and when it is more than the above range, it may cause fracture and embrittlement at the time of peeling.

According to need, other resins, colorants, antistatic agents, stabilizers, antioxidants, ultraviolet absorbers, fluorescent whitening agents, etc. other than polyester can also be contained in the base material layer, as long as the purpose of the present invention is not damaged. within the range.

Preferably, the thickness of the substrate layer is preferably 10 to 140 μm, more preferably 20 to 100 μm, particularly preferably 40 to 60 μm.

(Surface roughness)

The center line average roughness (Ra) of the surface of the matte layer of the present invention is 400-1000nm, and the ten-point average roughness (Rz) is 4000-8000nm. By making Ra and Rz within the above range, transfer The matte appearance of the surface of the subsequent electromagnetic wave shielding film and the like becomes good. When at least one of Ra or Rz is less than the lower limit, the effect of improving the matte appearance becomes insufficient. On the other hand, when at least one of Ra or Rz exceeds the upper limit, although the matte appearance is good, the unevenness of the surface is too severe, so the following disadvantages are likely to occur: during film formation, particles fall off; Heavy peeling occurs during the transfer process; etc. From such a viewpoint, the lower limit of Ra is preferably 500 nm, more preferably 600 nm, and the upper limit of Ra is preferably 800 nm, more preferably 750 nm. In addition, the lower limit of Rz is preferably 5000 nm, more preferably 6000 nm, and the upper limit of Rz is preferably 7500 nm, more preferably 7000 nm.

In addition, Ra and Rz can be obtained by using the particle|grains which have the above-mentioned average particle diameter and maximum particle diameter, and adjusting content in a mat layer, for example.

(Gloss: G ₆₀ )

For the biaxially oriented polyester film of the present invention, it is necessary for the glossiness (G ₆₀ ) of the surface of the mat layer to be 6-20, preferably 9-15. It should be noted that the glossiness (G ₆₀ ) here refers to a value measured with both the incident angle and the light receiving angle being 60° in accordance with JIS standard Z8741. By making glossiness into the said range, a matte surface appearance can be provided suitably to the transfer film surface, such as an electromagnetic wave shielding film. When the glossiness is less than the lower limit, the added amount of particles is increased, the film-forming property is deteriorated, and it is difficult to make the breakage rate of surface protrusions 20% or less, and heavy peeling occurs, which is not preferable. On the other hand, when the glossiness exceeds the upper limit, sufficient matte appearance cannot be provided to the surface of an electromagnetic wave shielding film etc., and it is unpreferable.

(porosity rate)

The porosity rate of the protrusions on the surface of the mat layer of the present invention must be 20% or less. When the value exceeds 20%, when the support film is peeled off after transfer, the protrusions with the perforations will become the cause of fracture during peeling. starting point, which is not ideal. From the above viewpoint, the porosity rate is preferably 15% or less, more preferably 10% or less. The lower limit is not particularly limited, and the lower the better, it is about 5% from the viewpoint of actual production.

It should be noted that the porosity of the surface protrusions can be easily realized by the following method: as mentioned above, the polyester used in the matting layer is a copolyester or a polyester composition that is melt-mixed with other types of polyester, so that A method of improving the stretchability of the polyester containing particles; further, a method of slightly increasing the intrinsic viscosity of the polyester to improve the stretchability of the polyester containing particles; and the like.

It should be noted that the porosity rate of the protrusions is calculated as follows: take a photo of the surface of the matte layer with FE-SEM, count the number of all protrusions, and the number of protrusions with voids around the protrusions (protrusion perforations), Calculated in the form of the ratio (%) of the number of damaged to the total number.

(surface energy)

In addition, the apparent surface tension of the surface of the mat layer of the present invention is preferably 60 dyn/cm or less, more preferably 58 dyn/cm or less, from the viewpoint of releasability. The above-mentioned surface tension can be achieved by reducing the porosity of the above-mentioned protrusions, and using a copolyester or a combination of polyesters containing a more hydrophobic diol component as the diol component of the polyester used in the matting layer. thing.

＜Film manufacturing method＞

When the main component of polyester is polyethylene terephthalate, the polyester film of this invention can be manufactured by the following method, for example. That is, the matting layer and the substrate layer are laminated and extruded by a co-extrusion method, cooled and solidified with a casting drum (castingdrum), and an amorphous unstretched film is made. Hereinafter, it may be called the machine direction, the continuous film production direction, the longitudinal direction or MD) and the transverse direction (the direction perpendicular to the continuous machine direction and the thickness direction. Hereinafter, it may be called the width direction, TD).

For longitudinal stretching, for example, stretching is performed at a temperature of 60 to 130°C, preferably 90 to 125°C, by 2.0 to 3.5 times, preferably 2.5 to 3.0 times. Stretching in the transverse direction is, for example, stretching at a temperature of 100 to 130°C, preferably 90 to 125°C, by 2.0 to 4.0 times, preferably 3.0 to 4.0 times. In addition, stretching in one direction may be carried out in two or more stages, but the final stretching ratio is preferably within the aforementioned range.

Next, heat fixing treatment is performed as necessary. For example, when the matte layer and the substrate layer are made of polyethylene terephthalate, at a temperature of 220 to 240° C., preferably at a temperature of 220 to 235° C., for 2 to 30 seconds, preferably 2 to 20 seconds, and further The thermal fixation is preferably performed within a time range of 3 to 10 seconds. At this time, in order to reduce the thermal shrinkage rate, it may be performed with a limit shrinkage or extension within 20%, or at a fixed length, and may be performed in two or more stages.

＜Other membrane properties＞

(intrinsic viscosity)

It is preferable that the intrinsic viscosity (IV) of the base material layer polyester which comprises the biaxially-oriented polyester film of this invention is the range of 0.50-0.70 dl/g. The above intrinsic viscosity is represented by a measured value in an o-chlorophenol solution at 25°C. The lower limit of the intrinsic viscosity is more preferably 0.56 dl/g, particularly preferably 0.60 dl/g, because peelability becomes better. In addition, the upper limit of the intrinsic viscosity is preferably 0.67 dl/g, more preferably 0.65 dl/g. When the intrinsic viscosity of the film is lower than the lower limit, the mechanical properties tend to be lowered and the handleability tends to become difficult. On the other hand, when the intrinsic viscosity of the film exceeds the upper limit, the viscosity increases excessively, the load in the production process of the film increases, and the productivity decreases.

On the other hand, in order to make the surface roughness, glossiness (G ₆₀ ) and surface porosity of the matte layer satisfy the above requirements, the matte layer contains a large amount of particles with the above-mentioned large average particle diameter. Therefore, from the viewpoint of operability such as peelability, it is preferable that the intrinsic viscosity of polyester is high, but when it becomes too high, it will interact with the situation that the content of particles is high, so that the film forming property is reduced. The type and content to adjust the intrinsic viscosity.

(film thickness)

The biaxially oriented polyester film of the present invention may have a thickness that can be used as a support film for transfer of an electromagnetic shielding film, etc., and is preferably 10 to 150 μm, more preferably 20 to 100 μm, particularly preferably 45 to 70 μm.

Example

Hereinafter, the present invention will be further described using examples. In addition, each characteristic value was measured by the following method.

1. Gloss (G ₆₀ )

It measured using the gloss meter "VGS-SENSOR" manufactured by Nippon Denshoku Industries Co., Ltd. according to JIS standard (Z8741). The incident angle and the light receiving angle were both measured at 60° (N=5), and the average value was used.

2. Average particle size

The particles were stirred in ethylene glycol with a mixer to a concentration of 3%, and measured using a laser scattering particle size distribution analyzer SALD-7000 manufactured by Shimadzu Corporation. The 50% volume particle diameter (D ₅₀ ) was obtained from the particle size distribution measurement result, and this was taken as the average particle diameter.

3. Particle content

A sample is cut from the layer where the particle content of the film sample is to be measured, and a solvent in which the polyester is dissolved but the particles are not dissolved is selected for dissolution treatment, and then the particles are centrifuged from the solution, and the ratio of the particles to the overall mass (mass % ) as the particle content.

4. The thickness of each layer of the film

Samples were cut out into triangles, fixed in embedding capsules, and embedded with epoxy resin. Then, for the embedded sample, use a microtome (ULTRACUT-S) to cut a section parallel to the longitudinal direction into a 50nm thick film slice, and then use a transmission electron microscope to observe and take pictures at an accelerating voltage of 100kv, and measure the The thickness of each layer was measured at 10 places respectively, and the average thickness was calculated|required about each layer. Regarding the mat layer, the measurement was performed on a portion where no particles were present.

5. Centerline average roughness Ra and ten-point average roughness Rz

According to JIS-B0601 and B0651, use a three-dimensional surface roughness meter (manufactured by Kosaka Laboratory, trade name: SURF CORDERSE-3CK), at the tip of the stylus R2μm, scanning pitch 2μm, scanning length 1mm, number of scanning lines 100, cutoff value Under the conditions of (cut-off) 0.25mm and magnification 5000 times, the center line average roughness Ra and ten-point average roughness Rz were measured.

6. Membrane intrinsic viscosity

Using o-chlorophenol, it measured in 25 degreeC atmosphere. In addition, the intrinsic viscosity of a base material layer shaved off the part of a base material layer from the biaxially-oriented polyester film, and measured it.

7. Protrusion porosity rate

Use FE-SEM to take photos of the surface of the matte layer of the sample film, count the number of protrusions that exist in an area of 0.5 ^mm2 (10 fields of view of 200 μm × 250 μm), and the number of holes that have occurred in it to determine Calculated in the form of the ratio (%) of the number to the total number.

In addition, in the surface photograph, the protrusion with the hole in the periphery was judged as the protrusion which the perforation generate|occur|produced.

8. Hue L value

Using a spectrocolorimeter SE6000 manufactured by Nippon Denshoku Industries Co., Ltd., the measurement of the hue L value was performed by reflection with a black plate on the substrate layer side of the sample film.

9. Apparent Surface Tension

In accordance with JIS K 6768, a wettability index solution was applied to the surface of the matte layer of the sample film to measure the apparent surface tension.

10. Peelability

On the surface of the sample film, a methyl melamine-based release layer (ATOMBOND RP-30-30 manufactured by Miha Research Institute) was formed with a thickness of 0.1 μm, and a UV-curable acrylic resin (Da Nissei Co., Ltd.) was coated thereon. Chemical industry, SEIKABEAM EXF-3005 (NS)) and solidified, thereby forming an insulating protective layer with a thickness of 5 μm, and by applying a conductive paste with the following composition, a conductive layer with a thickness of 15 μm was formed. A transfer film having an electromagnetic wave shielding film on a support film;

Dainichi Seika Co., Ltd., polyurethane resin UD1357: 60 parts by mass

Flake silver powder (average thickness 100nm, average particle size 5μm): 20 parts by mass

Dendritic silver-plated copper powder (average particle size: 5 μm): 20 parts by mass.

Next, the transfer film obtained above was bonded to a flexible printed circuit board (a polyimide layer (12.5 μm), an adhesive layer ( 15μm), copper foil layer (12μm), and polyimide layer (12.5μm) with a four-layer structure) surface, under the conditions of temperature 200°C, pressure 1MPa, and 1 hour. Release the pressure, cool the sample at room temperature to 25 °C, then peel off the support film by hand, and visually observe the surface of the transferred insulating protective layer. Use the following indicators to evaluate,

○: peeling: complete peeling;

△: Transfer: White foreign matter remains on the side of the electromagnetic wave shielding film;

X: Break: The transfer film was broken during peeling.

11. Delustering properties of products

Using the same method as the glossiness in 1 above, measure the glossiness (G ₆₀ ) of the surface of the insulating protective layer for the sample obtained in the above 9 after transfer of the insulating protective layer, and evaluate the results using the following indicators,

◎: Below 15...The matting property of the product is very good

○: More than 15 and 20 or less...The matting property of the product is good

X: More than 20... The matting property of the product is poor.

12. Visibility Evaluation of Membrane Samples

Drop a few drops of water on a black acrylic plate, place the sample film on it so that the matte layer is in contact with the acrylic plate, and check the air quality of the sample film while the air between the sample film and the acrylic plate is removed. Visibility (see ええ方) is evaluated with the following indicators,

◎: White...Good visibility

〇: Translucent... Insufficient visibility

×: Transparent...Visibility is poor.

[Example 1]

Add the particles and resin shown in Table 1 to polyethylene terephthalate (intrinsic viscosity: 0.63dl/g) to prepare the A-layer polymer for forming the mat layer (A-layer). In the same way, particles and resin are added in the content of Table 1 to make the B-layer polymer used to form the base layer (B-layer), and each is supplied to an extruder heated to 280°C, and used to form A/B A two-layer feeder device such as a laminated structure combines the A-layer polymer and the B-layer polymer, maintains the laminated state, melts and extrudes the sheet from the die onto a rotating cooling drum that has been maintained at 20°C, and produces To form an unstretched film, next, stretch the unstretched film 3.2 times in the longitudinal direction, then stretch 3.4 times in the transverse direction at 140°C, and heat-fix at 235°C to obtain a biaxially oriented polyester film (thickness 50 μm ). Table 1 shows the evaluation results of the obtained film.

[Example 2]

Except having set the content of the resin added to the A-layer polymer and the B-layer polymer to the content described in Table 1, it carried out similarly to Example 1, and obtained the biaxially-oriented polyester film. Table 1 shows the evaluation results of the obtained film.

[Example 3]

For the polyethylene terephthalate used in the layer B polymer, two types of intrinsic viscosity of 0.63dl/g and 0.68dl/g were used, and the mixing ratio was 7 parts by mass of the former and 2 parts by mass of the latter parts, except that, it was carried out similarly to Example 2, and the biaxially oriented polyester film was obtained. Table 1 shows the evaluation results of the obtained film.

[Examples 4-9, Comparative Examples 1-2]

As described in Table 1, except having changed the kind and quantity of the particle|grains and resin added to the A layer polymer and B layer polymer, it carried out similarly to Example 1, and obtained the biaxially oriented polyester film. Table 1 shows the evaluation results of the obtained film.

[Example 10]

Add the particles and resin shown in Table 2 to polyethylene terephthalate (intrinsic viscosity: 0.63dl/g) to make A-layer polymer for forming the matte layer (A-layer). In the same way as layer A, particles and resin are added at the content in Table 2 to make layer B polymers for forming the base material layer (layer B), which are respectively supplied to extruders heated to 280°C and used to form A A 2-layer feeder device such as the laminated structure of /B merges the A-layer polymer and the B-layer polymer, maintains the laminated state, and melts and extrudes the sheet from the die onto a rotating cooling drum maintained at 20°C , to make an unstretched film, next, stretch the unstretched film 3.2 times in the longitudinal direction, then stretch it 3.4 times in the transverse direction at 140°C, and heat fix it at 230°C to obtain a biaxially oriented polyester film ( Thickness 50μm). Table 2 shows the evaluation results of the obtained film.

[Examples 11, 13-15, Comparative Examples 3, 4]

A biaxially oriented polyester film was obtained in the same manner as in Example 10 except that the particles added to the layer A polymer and the layer B polymer, resin, and their contents were as described in Table 2. Table 2 shows the evaluation results of the obtained film.

[Example 12]

For the polyethylene terephthalate used in the layer B polymer, two types of intrinsic viscosity of 0.63dl/g and 0.68dl/g were used, and the mixing ratio was 7 parts by mass of the former and 2 parts by mass of the latter Parts, the particles added to the A-layer polymer and the B-layer polymer, the resin and their content are as described in Table 2, except that, in the same manner as in Example 11, a biaxially oriented polyester film was obtained. . Table 2 shows the evaluation results of the obtained film.

[Table 1]

.

[Table 2]

.

PBT in Table 1 and Table 2 means polybutylene terephthalate, PTMT means polytrimethylene terephthalate, and PCHT means polycyclohexanedimethylene terephthalate.

Industrial availability

For the biaxially oriented film of the present invention, when used as a support film for transfer of electromagnetic wave shielding films, etc., a good matte appearance can be imparted to the surface of the transferred electromagnetic wave shielding film, etc., and the transfer process Since the support film after transfer is excellent in peelability, its industrial utility value is very high.

Claims (10)

1. double axial orientated polyester film, it is the stacking of the extinction layer containing particle with substrate layer and at least one surface Polyester film, it is characterised in that the center line average roughness of the delustring layer surface（Ra）For 400~1000nm, 10 points averagely thick Rugosity（Rz）For 4000~8000nm, the glossiness on the surface（G₆₀）For 6~20, also, the holes rate of the projection on surface is 20% Below.

2. double axial orientated polyester film according to claim 1, wherein, the form and aspect L values of substrate layer are 60~80.

3. double axial orientated polyester film according to claim 1 or 2, wherein, the apparent surface tension force of the delustring layer surface is Below 60dyn/cm.

4. according to double axial orientated polyester film according to any one of claims 1 to 3, wherein, the polyester of extinction layer is constituted with poly- Ethylene glycol terephthalate is main component, and comprising selected from PTT, poly terephthalic acid fourth two It is at least one kind of in alcohol ester and cyclohexanedimethanol's dimethyl ester.

5. according to double axial orientated polyester film according to any one of claims 1 to 4, wherein, particle in extinction layer is averaged Particle diameter is 2.5~5.5 μm, and content is 5~18 mass %.

6. according to double axial orientated polyester film according to any one of claims 1 to 5, wherein, the particle in extinction layer is without fixed Shape silica or synthetic zeolite.

7. according to double axial orientated polyester film according to any one of claims 1 to 6, wherein, constitute the master of the polyester of substrate layer It is polyethylene terephthalate to want composition.

8. double axial orientated polyester film according to claim 7, wherein, the inherent viscosity for constituting the polyester of substrate layer is 0.56 ~0.70dl/g.

9. according to double axial orientated polyester film according to any one of claims 1 to 8, wherein, on the basis of substrate layer quality, base The particle content of material layer is below 3.0 mass %.

10. according to double axial orientated polyester film according to any one of claims 1 to 9, it is used as electromagnetic shielding film transfer Support membrane.