TW202321356A - biaxially oriented polyester film - Google Patents

Abstract

To provide a biaxially oriented polyester film that has highly smooth surfaces on both sides, thereby suppressing transfer roughness of a surface shape that is transferred onto a release layer after being wound as a roll, and having a smooth release surface. Provided is a biaxially oriented polyester film in which, among values of maximum protrusion heights in each field of view obtained by the following method on one surface (A surface) and the other surface (B surface), when the values of the maximum protrusion heights corresponding to values of the top 5% are respectively defined as Sp5%A (nm) and Sp5%B (nm), Sp5%A is 110 or lower, and Sp5%B is 150 to 1000. (Maximum protrusion height measurement method) Ten objective lenses are used with a scanning-type white light interference microscope (VertScan) to measure 100 fields of view of a surface image in a 561 [mu]m field of view, the maximum protrusion height Sp value in each field of view is obtained, and values corresponding to the top 5% are defined as the Sp5% values.

Description

biaxially oriented polyester film

The present invention relates to a biaxially oriented polyester film provided with surfaces having specific characteristics on both sides of the film.

Thermoplastic resins are used in various industrial fields due to their good processability. In addition, products obtained by processing these thermoplastic resins into films play an important role in today's daily life such as industrial applications, optical product applications, packaging applications, and magnetic recording tape applications. In recent years, electronic information equipment has progressed toward miniaturization, fineness, and high integration. Along with this, process films used in the manufacturing steps of electronic information equipment are required to be improved in processability. Demand for process films for the production of electronic parts, especially green sheet releases used in the manufacturing process of laminated ceramic capacitors, which has grown significantly in recent years, is increasing. Green sheets are thin-film ceramics obtained by coating and drying ceramic slurry on a release film, and the surface smoothness of the release film becomes important in the peeling process. This is because if the unevenness of the release surface is transferred to the surface of the green sheet, defects due to the unevenness will occur in the subsequent step of laminating the green sheet. However, the surface of the release layer is rough due to the transmission of the concave and convex shape of the substrate film surface, and it is difficult to maintain its surface smoothness because the surface shape of the opposite side of the release surface is transferred to the release surface when the roll is taken up. . Especially for the next-generation green sheet, since the thickness is as thin as 0.5 μm, it is necessary to maintain the smoothness of the release surface before and after roll winding.

Regarding such a problem, for example, Patent Document 1 discloses a method of controlling the surface roughness of both sides by controlling the particle size contained in the film, thereby suppressing the transfer of unevenness to the green sheet. [Prior Art Literature] [Patent Document]

Patent Document 1: Japanese Patent Laid-Open No. 2015-208939

[Problem to be solved by the invention]

However, the content of the particles in Patent Document 1 is high, which is insufficient for the next-generation application.

The object of the present invention is to control the height of the protrusions present on both sides of the film to provide a high smooth surface, which not only has excellent coatability or peelability at the time of sheet formation of the green sheet laminated through the release resin coating layer, but also can Significantly suppress surface defects and sheet cracks caused by transfer of the uneven shape of the green sheet. In addition, by suppressing the particle size and laminated thickness of the particles contained in the film, even when recycled resin raw materials are used as film raw materials, it is maintained. The aforementioned surface smoothness provides a biaxially oriented polyester film excellent in process handling properties (suppression of surface damage defects, surface chipping, and winding properties (winding wrinkles, winding deviation). [Means to solve the problem]

In order to solve the above-mentioned problems, the present invention adopts the following configurations. That is, [I] a biaxially oriented polyester film having a surface (side A) satisfying the following (1), and a surface opposite to the side A (side B) satisfying the following (2); (1) the foregoing A The surface has protrusions. Among the values of the maximum protrusion height in each field of view obtained by the following method, when the value of the maximum protrusion height corresponding to the upper 5% of the value is Sp5%A (nm), Sp5%A 110 or less; (2) The aforementioned surface B has protrusions, and among the values of the maximum protrusion heights in each field of view obtained by the following method, the value of the maximum protrusion height corresponding to the upper 5% value is set as Sp5% When B (nm), Sp5%B is 150 to 1000; (Measurement method of maximum protrusion height) Using a scanning white interference microscope (VertScan) with a 10 objective lens, measure the surface image of a 561 μm field of view in a field of view of 100, and obtain each As for the maximum protrusion height Sp value in the field of view, a value corresponding to the upper 5% thereof was defined as the Sp5% value. [II] The biaxially aligned polyester film as described in [I], wherein protrusions are present on the surface of the A-side, and when the number of protrusions with a height of 80 nm or more is N _80nm A (unit/mm ² ), N _80nm A 0.4 or less. [III] The biaxially oriented polyester film according to [I] or [II], wherein protrusions are present on the surface of the A-side, and when the number of protrusions with a height of 10 nm or more is N _{10 nm} A (unit/mm ² ) , N _10nm A is not less than 300 and not more than 1000. [IV] The biaxially oriented polyester film according to any one of [I] to [III], wherein the polyester resin layer (P1 layer) has the aforementioned A-side. [V] The biaxially oriented polyester film according to any one of [I] to [IV], wherein T _P1 is 2 or more and 10 or less when the thickness of the P1 layer is T _P1 (μm). [VI] The biaxially oriented polyester film according to any one of [I] to [V], wherein the P1 layer contains particles, and when the maximum particle diameter of the particles contained in the P1 layer is _DP1 (μm), T _P1 /D _P1 is not less than 20 and not more than 100. [VII] The biaxially oriented polyester film according to [I], wherein CaR is 100 to 120 when the water contact angle of the surface A is CaR (°). [VIII] The biaxially oriented polyester film as described in [VII], wherein the coating layer (R1 layer) has the aforementioned A surface, and the coating layer (R1 layer) is provided on the layer (P1) mainly composed of the aforementioned polyester resin. layer) above. [IX] The biaxially oriented polyester film as described in [VII] or [VIII], wherein the R1 layer contains at least one of silicone resin, long-chain alkyl resin or acrylic resin as a main component. [X] The biaxially oriented polyester film according to any one of [VII] to [IX], wherein T _R1 is 0.01 to 1.00 when the thickness of the P1 layer is T _R1 (μm). [XI] The biaxially oriented polyester film according to any one of [I] to [X], wherein when the layer having the aforementioned B surface is defined as the P2 layer, the layer containing The composition of P3 layer of particles is at least 3 layers. [XII] The biaxially oriented polyester film according to any one of [I] to [XI], wherein the P2 layer contains at least two types of particles having different average particle diameters. [XIII] The biaxially oriented polyester film according to any one of [I] to [XII], wherein the thickness of the aforementioned P2 layer is T P2 (μm), and the maximum particle diameter of the particles contained in the P2 layer is T _P2 (μm). When D _P2 (μm), T _P2 /D _P2 is 1 or more and 5 or less. [XIV] The biaxially oriented polyester film according to any one of [I] to [XIII], wherein the film thickness is measured in the film width direction (the same direction as the film roll width direction), and the average thickness of the film is set as T _AVE (μm), when the maximum value of the film thickness is T _MAX (μm) and the minimum value is T _MIN (μm), the thickness unevenness ΔT (%) expressed by the following formula (1) is 5.0 or less ; ΔT(%)=100×(T _MAX -T _MIN )/T _AVE・・・Formula (1). [XV] The biaxially oriented polyester film according to any one of [I] to [XIV], wherein the coefficient of static friction between the surface A and the surface B is 0.8 or less. [XVI] The biaxially oriented polyester film according to any one of [I] to [XV], which is used as a support film formed from a green sheet in the step of manufacturing a laminated ceramic capacitor. [Effect of Invention]

Although the biaxially oriented polyester film of the present invention has a highly smooth surface on both sides, the process handling properties (suppression of surface damage, surface chipping) and roll take-up properties (suppression of winding wrinkles, winding deviation) Excellent, since it suppresses the transfer roughness of the surface unevenness of the film wound up as a roll to the release layer, not only the coatability and peelability of the green sheet to be laminated, but also the cracking or surface defects of the green sheet can be suppressed .

In addition, the biaxially oriented polyester film of the present invention has good surface smoothness and mold release properties, and is particularly useful as a support film for green sheet molding in the steps of manufacturing multilayer ceramic capacitors.

[Mode for Carrying Out the Invention]

Hereinafter, the present invention will be described in detail.

This invention relates to biaxially oriented polyester films. The biaxially oriented polyester film of the present invention has a surface (side A) satisfying the following (1), and a surface (side B) opposite to the A side satisfying the following (2). (1) In the above-mentioned A surface, when the value of the maximum protrusion height corresponding to the upper 5% of the value of the maximum protrusion height in each field of view obtained by the following method is Sp5%A (nm), Sp5%A 110 or less. (2) In the above-mentioned B surface, when the value of the maximum protrusion height corresponding to the upper 5% of the value of the maximum protrusion height in each field of view obtained by the following method is Sp5%B (nm), Sp5%B 150 to 1000. (Measurement method of maximum protrusion height) Using a scanning white interference microscope (VertScan) with a 10 objective lens, measure the surface image of 561 μm□ field of view in 100 fields of view, obtain the maximum protrusion height Sp value in each field of view, and set the value corresponding to the upper 5% of them as Sp5% value. The detailed measurement method will be described later. The biaxially oriented polyester film of the present invention is preferably composed of a polyester resin layer (P1) having the aforementioned A side, an intermediate layer (P3) and a layer (P2) having the opposite side (B side) to the aforementioned A side, It adopts 3-layer laminate structure of P1 layer/P3 layer/P2 layer. Also, the biaxially oriented polyester film of the present invention preferably contains a coating layer (R1) having the aforementioned A side, consisting of a polyester resin layer (P1), an intermediate layer (P3) and a side (B side) opposite to the aforementioned A side. ) layer (P2), which is composed of 4 layers of R1 layer/P1 layer/P3 layer/P2 layer.

(surface with protrusions: A surface) In the present invention, the surface A has protrusions, and when the value of the maximum protrusion height of the upper 5% of the maximum protrusion height in each field of view obtained by the method described later is Sp5%A (nm), Sp5% A is 110 or less. When the biaxially oriented polyester film of the present invention is used as a process film for a green sheet in the manufacturing step of a laminated ceramic capacitor, Sp5%A is reflected in the step of coating and forming a green sheet requiring high smoothness. The value of the height of the protrusions whose shape is transferred to the surface affects the number of surface defects of the single green sheet and the number of defects in the step of laminating them to manufacture a ceramic capacitor. In the present invention, the value Sp5%A (nm) of the maximum protrusion height corresponding to the upper 5% of the value of the maximum protrusion height in each field of view obtained by the method described later is based on the software attached to the scanning white interference microscope. According to ISO 25178, the value measured by the measurement method described below. Since the above-mentioned Sp5%A (nm) in the above-mentioned A surface is 110 or less, the number of defects in the surface defects of the green sheet, the cracking of the green sheet, and the steps of laminating the green sheet to produce a ceramic capacitor can be respectively reduced. The more preferable range of the above-mentioned Sp5%A (nm) in the above-mentioned A surface is 100 or less, especially preferably 80 or less.

In the present invention, the number of projections N _80nm A (number/mm ² ) of the above-mentioned surface A with a height of 80nm or more is preferably 0.4 or less. When used as a process film of a green sheet in the manufacturing step of a laminated ceramic capacitor, the reflection will be coarse Concave-convex forms the number of protrusions transferred to the surface of the green sheet. In the present invention, the number of protrusions corresponding to each height is a value measured by the software attached to the scanning white interference microscope in accordance with ISO 25178 and the measurement method described later. Since the number N _80nm A (unit/mm ² ) of protrusions with a height of 80nm or more is set to 0.4 or less, local damage to the target member can be suppressed, and the number of surface defects of the single green sheet and the breakage of the green sheet can be further reduced and the number of defects in the steps of manufacturing ceramic capacitors by laminating them. The range of the number N _80nm A (piece/mm ² ) of protrusions with a height of 80 nm or more is more preferably 0.3 or less, particularly preferably 0.2 or less.

In the present invention, the number N _10nm A (pieces/mm ² ) of protrusions with a height of 10 nm or more on the surface A is preferably 300 to 1000, which is used in the film-forming step of biaxially aligned polyester film or in the manufacture of multilayer ceramic capacitors. In the step, the value of the slipperiness of the aforementioned surface A and the processing roll is reflected. Since the number N _10nm A (unit/mm ² ) of protrusions with a height of 10 nm or more is 300 or less, it is possible to suppress the introduction of flaws on the surface due to friction with the processing roll and decrease in film quality. Furthermore, since the number N _10nm A (number/mm ² ) of protrusions having a height of 10 nm or more is set to 1000 or less, it is possible to suppress occurrence of winding misalignment during roll winding. The preferable range of the number N _10nm A (number/mm ² ) of protrusions having a height of 10 nm or more is 400 to 1000.

(The side opposite to A side: B side) In the present invention, the surface opposite to the A surface (B surface) has protrusions, and the value of the maximum protrusion height corresponding to the value of the upper 5% of the maximum protrusion height in each field of view obtained by the method described later is Sp5% For B (nm), Sp5%B is not less than 150 and not more than 1000. When the biaxially oriented polyester film of the present invention is used as a process film for green sheets in the manufacturing process of laminated ceramic capacitors, Sp5%B reflects the transfer of concave and convex shapes to the release layer for green sheets during roll winding Or the value of the height of the protrusions on the surface of the laminated green sheet that requires high smoothness, not only transfers the concave-convex shape on the surface that is in contact with the green sheet, but also partially presses the green sheet into the demoulding On the side of the resin coating layer, the concave-convex shape of the surface of the release resin coating layer is transferred more significantly, which affects the number of surface defects of the green sheet itself and the number of defects in the step of laminating them to manufacture a ceramic capacitor. The aforementioned Sp5%B (nm) in the present invention is obtained by the software attached to the scanning white interference microscope, and is a value measured by the measurement method described later in accordance with ISO 25178. Since the aforementioned Sp5%B(nm) is 1000 or less, it is possible to reduce the number of defects in the steps of green sheet surface defects, green sheet cracks, and laminated green sheets to produce ceramic capacitors, respectively. The more preferable upper limit of the aforementioned Sp5%B (nm) is 700 or less. Also, since the aforementioned Sp5%B (nm) is set to 150 or more, the slipperiness of both sides of the film of the biaxially oriented polyester film can be improved, and the occurrence of winding wrinkles during roll winding can be suppressed. The lower limit of the aforementioned Sp5%B(nm) is more preferably 180 or more, particularly preferably 200 or more.

(Polyester resin layer: P1 layer) The biaxially oriented polyester film of the present invention has a layer (P1 layer) mainly composed of polyester resin, and when the surface of the P1 layer is the outermost surface of the biaxially oriented polyester film, it becomes The surface of the outermost P1 layer is preferably the aforementioned A surface. Hereinafter, the surface of the P1 layer is the outermost surface of the biaxially oriented polyester film, and the A-side is referred to as the A-side of the P1 layer. Since the surface of the P1 layer is the outermost surface of the biaxially oriented polyester film and is the aforementioned A side, when the coating layer is provided on the surface of the P1 layer, the maximum protrusion height and the number of protrusions on the coating layer surface can be controlled at a relatively low level. good range. In particular, the thickness of the coating layer (R1) described later is defined as T _R1 (μm), and T _R1 is 0.01 to 0.30. Since the surface of the P1 layer satisfies the requirements of the aforementioned A surface, it is easy to control so that the surface of the coating layer satisfies the above A. The essentials of the surface, so it is more appropriate.

(polyester resin) The biaxially oriented polyester film referred to in the present invention means a film mainly composed of polyester resin. The main component mentioned here means a component contained in more than 50% by mass out of 100% by mass of all components of the film.

In addition, the polyester resin referred to in the present invention is obtained by polycondensing dicarboxylic acid constituents and diol constituents. In addition, in this specification, a structural component shows the minimum unit obtained by hydrolyzing polyester.

Examples of dicarboxylic acid components constituting the polyester include terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalene dicarboxylic acid, 1,5-naphthalene dicarboxylic acid, 2, Aromatic dicarboxylic acids or their esters, such as 6-naphthalene dicarboxylic acid, 1,8-naphthalene dicarboxylic acid, 4,4'-diphenyl dicarboxylic acid, 4,4'-diphenyl ether dicarboxylic acid, etc. derivative.

In addition, examples of diol constituents constituting the polyester include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,2-butanediol, 1, Aliphatic diols such as 3-butanediol, alicyclic diols such as cyclohexanedimethanol and spirodiol, and combinations of the above-mentioned diols, etc.

As the polyester resin used in the present invention, from the viewpoint of mechanical properties and transparency, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), poly 2 , 6-ethylene naphthalene dicarboxylate (PEN) and isophthalic acid or naphthalene dicarboxylic acid are copolymerized in part of the dicarboxylic acid component of PET, and cyclohexane is copolymerized in part of the diol component of PET Dimethanol, spirodiol, and diethylene glycol polyesters, among which polyethylene terephthalate is particularly preferred.

The polyester film in the biaxially oriented polyester film of the present invention is preferably biaxially oriented. By biaxial alignment, the mechanical strength of the film is increased, wrinkles are less likely to be introduced, and the take-up property can be improved, and by applying uniform stretching stress in the stretching step, the smoothness of the surface can be made uniform in the entire film. The biaxial alignment mentioned here refers to those showing biaxial alignment patterns by wide-angle X-ray diffraction. Polyester film can generally be obtained by stretching an unstretched thermoplastic resin sheet along the length and width directions of the sheet, and then subjecting it to heat treatment to complete crystal alignment. Details will be described later.

In the above-mentioned A surface of the P1 layer of the present invention, as a method for making the above-mentioned Sp5%A (nm) into the above-mentioned range, the coarse particles are reduced by decomposing and removing the deteriorated foreign matter originating from the polyester resin existing on the surface. For the purpose of protrusions, there may be mentioned plasma surface treatment by corona treatment or atmospheric pressure glow discharge. From the viewpoint of suppressing excessive deterioration of the polyester resin constituting the A surface of the P1 layer and generation of foreign matter by surface treatment, it is more preferable to use plasma surface treatment by atmospheric pressure glow discharge.

The plasma surface treatment caused by atmospheric pressure glow discharge can be applied in the state of the extruded unstretched film in the polyester film manufacturing step, and can also be applied to the stretched film, but it can be smoothed From the point of view of imparting properties and slipperiness to the above-mentioned A surface, it is most preferable to apply plasma surface treatment by atmospheric pressure glow discharge in an unstretched film state. This is because the amorphous polyester part is shaved off by the plasma surface treatment caused by the atmospheric pressure glow discharge, and the crystalline polyester part remaining on the surface in the subsequent elongation step is crystallized and grown as a convex part. Fine protrusions are formed.

The atmospheric pressure mentioned here is in the range of 700 Torr to 780 Torr. Atmospheric pressure glow discharge treatment is to guide the film to be treated between the opposite electrode and the ground roller, introduce the plasma excited gas into the device, and apply a high frequency voltage between the electrodes, so that the gas can be excited by plasma. A glow discharge is performed between the electrodes. Thereby, the surface of the film is microfabricated (ashed) to form protrusions.

The so-called plasma-excited gas refers to a gas that can be excited by plasma under the aforementioned conditions. Examples of plasma exciting gases include rare gases such as argon, helium, neon, krypton, and xenon; chlorofluoroalkanes such as nitrogen, carbon dioxide, oxygen, and tetrafluoromethane, and mixtures thereof. Moreover, the plasma excitation gas may be used individually by 1 type, and may use it in combination of 2 or more types by arbitrary mixing ratios. From the viewpoint of high activity when excited by plasma, it is preferable to contain oxygen in addition to at least one of argon, oxygen, and carbon dioxide. In addition, by using a highly active plasma-exciting gas, the number of fine protrusions formed on the surface of the film can be increased, and slipperiness may be further improved.

The frequency of the high-frequency voltage in the plasma treatment is preferably in the range of 1 kHz to 100 kHz. Also, from the viewpoint of protrusion formation, the discharge treatment intensity (E value) obtained by the following method is preferably within the range of 50-2000W·min/ ^m2 , more preferably 150-1000W·min /m ² . By increasing the discharge treatment intensity (E value) to more than 50W·min/ ^m2 , the effect of forming fine protrusions on the surface can be exhibited, and at the same time, the thickness unevenness in the width direction of the biaxially oriented polyester film described later can be reduced. By suppressing the discharge treatment intensity (E value) below 2000W·min/m ² , it is possible to suppress the formation of surface foreign objects with a height of 80nm or more due to excessive damage to the surface of the polyester film.

<Calculation of discharge treatment intensity (E value)> E=Vp×Ip/(S×Wt) E: E value (W·min/m ² ) Vp: Applied voltage (V) Ip: Applied current (A) S: Processing speed (m/min) Wt: processing width (m) In general, the ashing (ashing) of the surface of a polyester film, especially a film having an amorphous part and a crystalline part such as PET or PEN, is performed by atmospheric pressure glow discharge treatment. ), it is ashed from the soft amorphous part. By making the crystalline part and the amorphous part finer, finer protrusions can be formed by atmospheric pressure glow discharge treatment, and by increasing the crystalline part in advance, the soft amorphous part is deeply cut, and the post-stretching step can be further improved. The resulting protrusion height.

When the thickness of the P1 layer in the present invention is defined as T _P1 (μm), T _P1 (μm) is preferably 2 or more and 10 or less. Since the thickness T _P1 (μm) of the P1 layer is set to 2 or more, even when coarse particles are added to the P3 layer and P4 layer described later, the influence of the shape of those particles on the A surface can be minimized. In particular, with regard to the coarse particles added in the P3 layer and P4 layer described later, in the volume-based particle size distribution analysis described later, when the particle diameter showing a very large peak exceeds 800 nm, the influence on the aforementioned A surface changes significantly, Therefore, the thickness T _P1 (μm) of the P1 layer is preferably set to 3 or more, more preferably 5 or more. Also, since the thickness T _P1 (μm) of the P1 layer is set to be 10 or less, it is possible to increase the ratio of the intermediate layer (P3) using recovered raw materials described later while reducing the thickness of the entire film. The upper limit of the thickness T _P1 (μm) of the P1 layer is more preferably in the range of 8 or less.

The P1 layer of the biaxially oriented polyester film of the present invention can be blended with particles and heat-resistant stabilizers, oxidation-resistant stabilizers, antistatic agents, organic/inorganic easily Additives for slip agents, nucleating agents, dyes, dispersants, coupling agents, wavelength conversion materials, etc.

In addition, in the P1 layer of the biaxially oriented polyester film of the present invention, for the purpose of controlling the above-mentioned Sp5%A (nm) in the above-mentioned A surface of the P1 layer, particles may be contained, but those without particles are more preferable. good shape.

The particles to be added are not particularly limited, and either inorganic particles or organic particles may be used, or two or more kinds of particles may be used in combination. Examples of inorganic particles include calcium carbonate, magnesium carbonate, zinc carbonate, titanium oxide, zinc oxide, cerium oxide, magnesium oxide, barium sulfate, zinc sulfide, calcium phosphate, alumina (α alumina, β alumina, γ Alumina, delta alumina), mica (mica), mica, mica titanium, zeolite, talc, clay, kaolin, lithium fluoride, calcium fluoride, montmorillonite, zirconia, wet silica, dry silica Silicon, colloidal silicon dioxide, etc. Examples of organic particles include organic particles comprising acrylic resins, styrene resins, silicone resins, polyimide resins, and the like as constituents, core-shell organic particles, and the like.

The average particle diameter of the particles is preferably not less than 10 nm and not more than 100 nm in order to prevent protrusions of not less than 110 nm from being formed on the surface.

From the viewpoint of suppressing chipping of the coating layer (R1 layer) to be described later during step transfer, it is preferable to use particles having a high Mohs hardness while keeping the average primary particle diameter of the particles contained in the P1 layer at 50 nm or less. Cutting during step conveyance is a sudden load on the surface of the coating layer, and when the P1 layer adjacent to the resin constituting the coating layer is excessively deformed, the coating layer may be cut locally starting from the particles with high hardness. Therefore, since the adjacent P1 layer contains particles having a high Mohs hardness, and the particles are dispersed with an average primary particle diameter of 50 nm or less, the hardness of the P1 layer itself can be apparently increased, and deformation can be suppressed. And inhibit the chipping of the coating layer. Among the particles described above, aluminum oxide (Mohs hardness: 9) is preferably used as particles having a high Mohs hardness. The more preferable range of the average primary particle diameter is 30 nm or less, especially preferably 20 nm or less. When the P1 layer contains alumina having an average primary particle size of 50 nm or less, the amount of particles added to the P1 layer is preferably 0.5% by mass or less. By setting the particle addition amount to 0.5% by mass or less, the sudden formation of coarse particles exceeding 110 nm due to the aggregation of individual particles can be suppressed, and surface defects or chip breakage of the green sheet can be suppressed. The preferable range of the addition amount of the alumina particle whose average primary particle diameter is 50 nm or less is 0.3 mass % or less.

As a more preferable embodiment, when the thickness of the P1 layer is T _P1 (μm) and the maximum particle size contained in the P1 layer is D _P1 (μm), T _P1 /D _P1 is preferably 20 or more and 100 or less. T _P1 /D _P1 is a value that reflects the proportion of particles in the P1 layer. Since T _P1 /D _P1 is set to 20 or more, it is possible to suppress the formation of coarse protrusions on the aforementioned surface. Since T _P1 /D _P1 is set to Below 100, the number of protrusions with a height above 10 nm can be increased to improve the slipperiness of the P1 layer.

Also, the amount of particles contained in the P1 layer of the present invention is not particularly limited, but in order to prevent the formation of protrusions of 110 nm or more on the surface, it is preferably 0.5% by mass or less, more preferably 0.2% by mass or less, especially 0.2% by mass or less. Preferably, it is 0.1% by mass or less.

(The layer having the aforementioned B side: P2 layer) When the layer having the B-side in the biaxially oriented polyester film of the present invention is defined as the P2 layer, the P2 layer is preferably composed of a polyester resin as the main component, similarly to the P1 layer.

The particles contained in the P2 layer of the present invention preferably have an average particle diameter obtained by the method described later, of not less than 100 nm and not more than 900 nm.

In addition, as the average particle diameter of the aforementioned particles (details will be described in the description of the measurement method later), it is preferable to include two or more kinds of particles with different average particle diameters. Since it contains particles with different average particle diameters, it forms a surface with many protrusions with different heights, so the contact area between the films can be efficiently reduced, and at the same time, the biting of air can be suppressed during winding. As a preferable combination of average particle diameters, when the volume-based particle size distribution measurement is performed on the added particles, the particle diameter is plotted on the horizontal axis, and the abundance ratio of the particles is plotted on the vertical axis, the particle diameter is preferably in the region of 30nm or more and less than 1200nm It has two peaks, more preferably one or more peaks in each of the region with a particle diameter of 30 nm to less than 400 nm and the region with a particle diameter of 400 nm to less than 1200 nm.

As a more preferable aspect of the particle size contained in the P2 layer, when the thickness of the P2 layer is defined as T _P2 (μm) and the maximum particle size contained in the P2 layer is defined as D _P2 (μm), the ratio of T _P2 /D _P2 is Better to be 1 or more and 5 or less. T _P2 /D _P2 is a value reflecting the proportion of particles in the P2 layer. Since T _P2 /D _P2 is set to 1 or more, it is possible to suppress the formation of coarse protrusions on the B surface. Since T _P2 /D _P2 When it is set to 5 or less, the air removal when the films overlap each other becomes good, and the generation of wrinkles at the time of roll winding can be suppressed. T _P2 (μm), which is the thickness of the P2 layer, is not particularly limited, but by setting it from 1 to 10, the relationship between the aforementioned particles and the thickness of the laminate can be controlled, and the P3 described later can be increased in the same film thickness. The ratio of layers improves recyclability.

The particles contained in the P2 layer of the biaxially oriented polyester film of the present invention are not limited as in the above-mentioned P1 layer, and either inorganic particles or organic particles can be used. Examples of inorganic particles include calcium carbonate, magnesium carbonate, zinc carbonate, titanium oxide, zinc oxide, cerium oxide, magnesium oxide, barium sulfate, zinc sulfide, calcium phosphate, alumina (α alumina, β alumina, γ Alumina, delta alumina), mica, mica, mica titanium, zeolite, talc, clay, kaolin, lithium fluoride, calcium fluoride, montmorillonite, zirconia, wet silica, dry silica, colloid Silicon dioxide, etc. Examples of organic particles include organic particles comprising acrylic resins, styrene resins, silicone resins, polyimide resins, and the like as constituents, core-shell organic particles, and the like.

The amount of particles added to the P2 layer of the biaxially aligned polyester film of the present invention is not particularly limited, but from the viewpoint of controlling the aforementioned Sp5%B (nm) in the aforementioned B surface within a preferred range, It is preferable to set the content concentration in the P2 layer to be 3% by mass or less. If it exceeds 3% by mass, even if particles having an average particle diameter within the preferred range are used, the film will be partially clouded, and the light transmittance and haze described later may deviate from the preferred range. More preferably, it is 2 mass % or less, especially 1 mass % or less.

Regarding the method of forming the P2 layer in the biaxially oriented polyester film of the present invention, it is possible to use: a method of extruding in a state where the P1 layer and the P3 layer described later are laminated together (co-extrusion method), or other resin layer raw materials The method of putting it into an extruder for melt extrusion and laminating it on the film in the middle of film production while extruding from the metal nozzle, the method of laminating the films after film production through an adhesive layer, etc.

(Middle layer: P3 layer) The biaxially oriented polyester film of the present invention preferably has a P3 layer between the aforementioned P1 layer and P2 layer. The particles and additives contained in the P3 layer can be added as long as they do not affect the smoothness of the surface of the P1 layer (A side) and the surface of the P2 layer (B side). Among them, it is preferable to use the biaxially aligned polyester film of the present invention as a recycled raw material and add it to the P3 layer from the viewpoint of reducing the environmental load as a film product. The recycled raw material of the aforementioned biaxially oriented polyester film can be a recycled raw material composed of the entire biaxially oriented polyester film, or can be made by removing the P1 layer, especially the P1 layer or P2 layer laminated with the coating layer (R1 layer) described later. Recycled raw materials composed of the later parts. As the method of making recovered raw materials, commonly used methods can be used, for example, the method of crushing the scrap film produced in the cutting step in the film forming step, and then compacting it into a scale. A method of melting, extruding, and fragmenting, or recovering waste films used in the manufacturing process of laminated ceramic capacitors, and peeling off the coating layer existing on the polyester film with water or an alkaline solution (alkaline solution) , the method of crushing once and then compacting to form scales, or the method of melting, extruding, and fragmenting after crushing, etc. The content of the recycled raw material component in the P3 layer is preferably 15% by mass or more and 50% by mass or less. Since the content of recycled raw materials is set at 15% by mass or more, the scrap film generated in the film-making step described above can be used as a biaxially oriented polyester film without being discarded. The strength or durability of the stretched film is excessively reduced.

(biaxially oriented polyester film) The polyester film in the biaxially oriented polyester film of the present invention is preferably biaxially oriented. By biaxial alignment, the mechanical strength of the film is increased, wrinkles are less likely to be introduced, and the take-up property can be improved, and by applying uniform stretching stress in the stretching step, the smoothness of the surface can be made uniform in the entire film. The biaxial alignment mentioned here refers to those showing biaxial alignment patterns by wide-angle X-ray diffraction. Polyester film can generally be obtained by stretching an unstretched thermoplastic resin sheet along the length and width directions of the sheet, and then subjecting it to heat treatment to complete crystal alignment. Details will be described later.

In the biaxially oriented polyester film of the present invention, the intrinsic viscosity (IV) of the polyester film is preferably at least 0.50 dl/g, more preferably at least 0.60 dl/g. IV is a number reflecting the length of the molecular chain. The longer the molecular chain is, the easier it is to form the crystalline part and the amorphous part in the same molecular chain, so it is easier to form finer protrusions by atmospheric pressure glow discharge treatment, so it is more suitable. In addition, since the IV is set to 0.50 dl/g or more, the polyester molecular chain is short and can be crystallized, and it is possible to suppress frequent occurrence of breakage in the stretching step and difficulty in film formation.

The biaxially oriented polyester film of the present invention preferably has the above-mentioned P1 layer, P2 layer, and P3 layer, and the above-mentioned surface and its opposite surface are arranged on the outermost surface of at least 3 or more layers (P1 layer/P3 layer/P2 layer).

There is no particular limitation on the method of laminating other resin layers such as the P1 layer, P2 layer, and P3 layer. The co-extrusion method described later can be used, or other resin layer raw materials can be put into the extruder for melt extrusion The method of extruding from the metal mouth and laminating it on the film in the process of film production, the method of laminating the films after film production through the adhesive layer, etc., among them, it is preferable to use the process of forming protrusions and Layered co-extrusion method.

The biaxially oriented polyester film of the present invention preferably has a static friction coefficient (μs) of not less than 0.3 and not more than 0.8 on both sides of the film (the aforementioned A surface and the aforementioned B surface) from the viewpoint of film roll rewindability. Since the coefficient of static friction (μs) on both sides of the film is set to 0.3 or more, it is possible to suppress excessive sliding of the films and the winding deviation of the roll when the roll is taken up. When it is 0.8 or less, it is possible to suppress the generation of wrinkles due to adhesion of both sides of the film during roll winding. The upper limit of the coefficient of static friction (μs) on both surfaces of the film (the aforementioned A-side and the aforementioned B-side) is more preferably 0.7 or less, particularly preferably 0.6 or less. Moreover, the biaxially oriented polyester film of this invention may provide the coating layer (R1 layer) mentioned later on the outermost surface. When the biaxially oriented polyester film of the present invention has a coating layer, it is preferably composed of the above-mentioned P1 layer, P2 layer, P3 layer and the R1 layer of the coating layer, with the R1 layer and the P2 layer being the outermost form. A configuration of at least four or more layers (R1 layer/P1 layer/P3 layer/P2 layer) is arranged.

When the total layer thickness of the biaxially oriented polyester film of the present invention is T (μm), T is preferably 15 or more and 100 or less. Since the overall layer thickness T (μm) is set to 15 or more, when used as a film for the production step of biaxially oriented polyester film and the film for the production step of laminated ceramic capacitors, the occurrence of stretching or heat treatment in the processing step can be suppressed. If the film is cracked, in addition, since the total layer thickness T (μm) is set to 100 or less, the film rigidity of the biaxially oriented polyester film can be prevented from becoming excessively high, and the processability of the thermal lamination step in the manufacture of electronic parts can be improved. good. A more preferable range of the total layer thickness T (μm) is 20 to 50.

When the thickness variation of the biaxially oriented polyester film of the present invention is defined as ΔT (%), ΔT is preferably 5.0 or less. The aforementioned thickness unevenness ΔT(%) is to measure the film thickness in the width direction of the film roll by the method described later, and set the average thickness of the film thickness as T _AVE (μm), and set the maximum value of the film thickness as T _MAX (μm), when the minimum value is T _MIN (μm), it becomes a value represented by the following formula (1). ΔT(%)=100×(T _MAX -T _MIN )/T _AVE・・・Equation (1) By setting ΔT(%) below 5.0, the surface shape of the above-mentioned surface can be maintained in the entire area of the film roll, preventing The surface shape of the above-mentioned surface changes due to local uneven thickness, and surface defects of the target member occur. In addition, from the viewpoint of the winding property of the film, by setting ΔT(%) to 5.0 or less, it is possible to suppress winding deviation caused by uneven thickness of the film. A more preferable range of ΔT(%) is 3.0 or less.

As a method of controlling ΔT(%) in a preferable range, for example, in order to reduce the thickness unevenness of the polyester film, the method of making the slit width of the T-die during extrusion uniform in the width direction, or In the stretching in the width direction using a tenter described later, the temperature applied to the biaxially oriented polyester film is made uniform in the width direction by reducing the widthwise unevenness of the stretching temperature or making the relaxation treatment an appropriate range, thereby suppressing Methods of uneven thickness due to poor elongation, etc. Furthermore, thickness unevenness can be reduced by applying the aforementioned plasma surface treatment by atmospheric pressure glow discharge. This is due to the plasma surface treatment caused by atmospheric pressure glow discharge. When the roll stretching method in the longitudinal direction described later is used, the adhesion between the film and the roll is improved, so the heating efficiency of the film before stretching is increased. The film can be stretched evenly without sliding on the stretching roller, and the occurrence of thickness unevenness in the width direction can be suppressed. The plasma surface treatment caused by the aforementioned atmospheric pressure glow discharge can also be used as a means to reduce the uneven thickness of the coating layer when the coating layer (R1 layer) is provided. By applying the surface treatment, since the maximum protrusion height on the surface of the P1 layer is controlled within a preferable range, it is possible to suppress the increase of thickness unevenness due to partial coating defects. In addition, since the functional groups generated by the above-mentioned surface treatment also remain on the surface of the P1 layer after the polyester film is formed, the affinity with the coating layer is improved, and the coating property is improved. Occurrence of uneven thickness. These effects are particularly easy to obtain when T _R1 (μm) of the thickness of the coating layer is 0.01 to 0.30.

唑啉化合物、碳二亞胺化合物、丙烯酸樹脂、聚矽氧樹脂的至少1種之樹脂或化合物(B)之塗料組成物而構成。又，R1層較佳為至少以丙烯酸樹脂或聚矽氧樹脂之一者作為主成分。由於成為這樣的構成，將前述R1層最表面之水接觸角設為CaR(°)時，可將CaR(°)控制在100以上120以下，使對象構件之形成與剝離成為良好。由於將前述R1層表面之水接觸角的CaR(°)設為100以上，可展現與生胚薄片的脫模性，由於將前述R1層表面之水接觸角的CaR(°)設為120以下，可在無龜裂(crawling)下塗布生胚薄片。CaR(°)的更佳下限值為105以上。 關於前述P1層所含有的聚矽氧化合物量，測定方法之詳細係如後述，但於飛行時間型2次離子質量分析(GCIB-TOF-SIMS)中，可以源自聚二甲基矽氧烷的片段之波峰強度(P)相對於在最大強度所檢測出的片段之波峰強度(K)之比(P/K)[-]來算出。 (Coating layer: R1 layer) The biaxially oriented polyester film of the present invention may include a coating layer (R1) having the aforementioned A surface on the outermost surface. The aforementioned R1 layer is preferably used to contain a release agent (A) and selected from epoxy resin, melamine resin,

A paint composition comprising at least one resin or compound (B) selected from an oxazoline compound, a carbodiimide compound, an acrylic resin, and a silicone resin. In addition, the R1 layer preferably contains at least one of acrylic resin and silicone resin as a main component. With such a configuration, when the water contact angle of the outermost surface of the R1 layer is CaR (°), CaR (°) can be controlled to 100 to 120, and the formation and peeling of the target member can be made good. Since the CaR(°) of the water contact angle on the surface of the R1 layer is set to 100 or more, the releasability with the green sheet can be exhibited, and since the CaR(°) of the water contact angle on the surface of the R1 layer is set to 120 or less , green flakes can be coated without cracking (crawling). A more preferable lower limit of CaR(°) is 105 or more. As for the amount of polysiloxane contained in the aforementioned P1 layer, the details of the measurement method will be described later, but in time-of-flight secondary ion mass spectrometry (GCIB-TOF-SIMS), it can be derived from polydimethylsiloxane The ratio (P/K) [-] of the peak intensity (P) of the fragment to the peak intensity (K) of the fragment detected at the maximum intensity was calculated.

When using the biaxially oriented polyester film of the present invention as a film for the green sheet release step in the manufacturing step of a laminated ceramic capacitor, the tape peeling force from the surface (A side) of the aforementioned R1 layer obtained by the measurement method described later is set. When it is FA (mN/19mm), FA is preferably from 5 to 50. Since the FA (mN/19mm) is set to 50 or less, green sheets made of thin film ceramics such as barium titanate can be peeled off without damage or defects, and since the FA (mN/19mm) is set to 5 or more, it is possible to prevent The defect that the green sheet floats from the aforementioned surface occurs inadvertently during the step handling. The more preferable range of the tape peeling force FA (mN/19mm) of the said surface is 5-30.

＜Release agent (A)＞ The release agent (A) in the present invention means a compound that imparts release properties to the surface of the coating layer by being contained in the coating composition. Examples of the release agent (A) usable in the present invention include long-chain alkyl group-containing resins, olefin resins, fluorine compounds, wax-based compounds, and the like. Among these, long-chain alkyl group-containing resins are preferable in terms of imparting good releasability.

As long-chain alkyl-containing compounds, commercially available ones can be used. Specifically, the "ASHIO resin" (registered trademark) series of long-chain alkyl-based compounds manufactured by Ashio Sangyo Co., Ltd., and the product manufactured by Lion Specialty Chemicals Co., Ltd. can be used. "Pyroyl" series of long-chain alkyl compounds, "Lisem" series of aqueous dispersions of long-chain alkyl compounds manufactured by Chukyo Oil & Fat Co., Ltd., etc. The release agent (A) preferably has an alkyl group having 12 or more carbon atoms, more preferably an alkyl group having 16 or more carbon atoms. By making the carbon number of an alkyl group into 12 or more, hydrophobicity improves and sufficient mold release performance can be exhibited as a mold release agent (A). When the carbon number of an alkyl group is less than 12, there exists a possibility that mold release performance may become inadequate. The upper limit of the carbon number of the alkyl group is not particularly limited, but it is preferably 25 or less because production is easy.

The aforementioned resin having an alkyl group having 12 or more carbon atoms is more preferably a resin having a side chain of an alkyl group having 12 or more carbon atoms on the polymethylene main chain. Since the main chain is polymethylene, the number of hydrophilic groups in the entire resin decreases, so that the release agent (A) can be made more excellent in the release effect.

In addition, regarding the presence or absence of an alkyl group having 12 carbon atoms, it is also possible to use the corresponding alkyl group in the signal obtained by the laminated film, for example, in TOF-SIMS (TOF-SIMS: time-of-flight secondary ion mass spectrometry). Evaluate the strength of the object. In this case, by using the chipping method by the ion sputtering method in combination, continuous measurement can be performed in the depth direction, and the distribution state of the alkyl group-containing compound can also be evaluated.

唑啉化合物、碳二亞胺化合物、丙烯酸樹脂、聚矽氧樹脂等。其中，三聚氰胺樹脂或丙烯酸樹脂，由於容易控制羥基所致的相互作用，且高溫加熱所致的樹脂層變容易變化而較宜。 <Resin or compound (B)> Examples of the resin or compound (B) usable in the R1 layer of the present invention include epoxy resin, melamine resin,

Azoline compounds, carbodiimide compounds, acrylic resins, silicone resins, etc. Among them, melamine resin or acrylic resin is preferable because it is easy to control the interaction of hydroxyl groups and the resin layer is easily changed by heating at a high temperature.

Among the epoxy resins usable as resin or compound (B), for example, sorbitol polyglycidyl ether crosslinking agent, polyglycerol polyglycidyl ether crosslinking agent, diglycerol polyglycidyl ether crosslinking agent, diglycerol polyepoxy Propyl ether-based crosslinking agents, polyethylene glycol diglycidyl ether-based crosslinking agents, and the like. Commercially available epoxy resins can also be used. For example, Nagase ChemteX Co., Ltd. epoxy compound "Denacol" (registered trademark) EX-611, EX-614, EX-614B, EX-512, EX -521, EX-421, EX-313, EX-810, EX-830, EX-850, etc.), diepoxy and polyepoxy compounds manufactured by Sakamoto Pharmaceutical Co., Ltd. (SR-EG, SR-8EG , SR-GLG, etc.), epoxy crosslinking agent "EPICLON" (registered trademark) EM-85-75W or CR-5L manufactured by Dainippon Ink Industry Co., Ltd., among which water-soluble ones are more suitable.

Melamine resins that can be used as the resin or compound (B) include, for example, melamine, methylolated melamine derivatives obtained by condensing melamine and formaldehyde, and partially or completely etherified by reacting lower alcohols with methylolated melamine. compounds and mixtures thereof. Moreover, as a melamine resin, either monomer or the condensate which consists of a multipolymer of a dimer or more may be sufficient, and these mixtures may be sufficient as it. As the lower alcohol used for etherification, methanol, ethanol, isopropanol, n-butanol, isobutanol, and the like can be used. The functional group is an imino group, a methylol group, or a methoxymethyl group or a butoxymethyl group that has an alkoxymethyl group in one molecule, and the imino group-type methylated melamine resin, methylol group, etc. Type melamine resin, methylol type methylated melamine resin and complete alkyl type methylated melamine resin, etc. Among them, it is most preferable to use a methylolated melamine resin.

唑啉化合物，係在該化合物中具有

唑啉基作為官能基者，較佳為由至包含1種以上的含有

唑啉基的單體，且使至少1種的其它單體共聚合而得之含

唑啉基的共聚物所構成者。Also, available as resin or compound (B)

An oxazoline compound having in the compound

As the functional group, the oxazoline group preferably contains at least one

An oxazoline-based monomer, and copolymerization of at least one other monomer containing

Composed of oxazoline-based copolymers.

唑啉基的單體，可使用2-乙烯基-2-

唑啉、2-乙烯基-4-甲基-2-

唑啉、2-乙烯基-5-甲基-2-

唑啉、2-異丙烯基-2-

唑啉、2-異丙烯基-4-甲基-2-

唑啉及2-異丙烯基-5-乙基-2-

唑啉等，亦可使用此等的1種或2種以上之混合物。其中，2-異丙烯基-2-

唑啉係在工業上亦容易取得到較宜。as containing

Azoline-based monomers, 2-vinyl-2-

Azoline, 2-vinyl-4-methyl-2-

Azoline, 2-vinyl-5-methyl-2-

Azoline, 2-isopropenyl-2-

Azoline, 2-isopropenyl-4-methyl-2-

Azoline and 2-isopropenyl-5-ethyl-2-

An oxazoline and the like can also be used as one or a mixture of two or more of them. Among them, 2-isopropenyl-2-

The oxazolines are also easy to obtain industrially.

唑啉化合物中，對於含有

唑啉基的單體所使用的至少1種其它單體，係與該含有

唑啉基的單體能共聚合的單體，例如可使用丙烯酸甲酯、甲基丙烯酸甲酯、丙烯酸乙酯、甲基丙烯酸乙酯、丙烯酸丁酯、甲基丙烯酸丁酯、丙烯酸-2-乙基己酯、甲基丙烯酸-2-乙基己酯等之丙烯酸酯或甲基丙烯酸酯類、丙烯酸、甲基丙烯酸、伊康酸、馬來酸等之不飽和羧酸類、丙烯腈、甲基丙烯腈等之不飽和腈類、丙烯醯胺、甲基丙烯醯胺、N-羥甲基丙烯醯胺、N-羥甲基甲基丙烯醯胺等之不飽和醯胺類、乙酸乙烯酯、丙酸乙烯酯等之乙烯酯類、甲基乙烯基醚、乙基乙烯基醚等之乙烯基醚類、乙烯、丙烯等之烯烴類、氯乙烯、偏二氯乙烯、氟乙烯等之含鹵素-α,β-不飽和單體類、苯乙烯及α-甲基苯乙烯等之α,β-不飽和芳香族單體類等，此等亦可使用1種或2種以上的混合物。At

Among the oxazoline compounds, for containing

At least one other monomer used in the oxazoline-based monomer is related to the

Azoline-based monomers can be copolymerized monomers, such as methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, acrylate-2- Acrylates or methacrylates such as ethylhexyl and 2-ethylhexyl methacrylate, unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, etc., acrylonitrile, methyl Unsaturated nitriles such as acrylonitrile, acrylamide, methacrylamide, N-methylolacrylamide, unsaturated amides such as N-methylolmethacrylamide, vinyl acetate , vinyl esters such as vinyl propionate, vinyl ethers such as methyl vinyl ether and ethyl vinyl ether, olefins such as ethylene and propylene, vinyl chloride, vinylidene chloride, vinyl fluoride, etc. Halogen-α,β-unsaturated monomers, α,β-unsaturated aromatic monomers such as styrene and α-methylstyrene, and the like can also be used alone or as a mixture of two or more.

Also, the carbodiimide compound that can be used as the resin or compound (B) has one or more carbodiimide groups or cyanamide groups with tautomerism in the molecule of the compound. Compounds as functional groups. Specific examples of such carbodiimide compounds include dicyclohexylmethanecarbodiimide, dicyclohexylcarbodiimide, tetramethylxylylenecarbodiimide, and urea-modified carbodiimide Amine etc., these can also use 1 type or the mixture of 2 or more types.

The coating layer of the biaxially aligned polyester film of the present invention may also contain an isocyanate compound as the resin or the compound (B). Examples of isocyanate compounds include toluene diisocyanate, diphenylmethane-4,4'-diisocyanate, m-xylylene diisocyanate, hexamethylene-1,6-diisocyanate, 1,6-diisocyanate, Isocyanate hexane, adducts of toluene diisocyanate and hexanetriol, adducts of toluene diisocyanate and trimethylolpropane, polyol modified diphenylmethane-4,4'-diisocyanate, carbodiethylene Amine-modified diphenylmethane-4,4'-diisocyanate, isophorone diisocyanate, 1,5-naphthalene diisocyanate, 3,3'-xylenyl-4,4'-diisocyanate, 3,3 'Dimethyldiphenylmethane-4,4'-diisocyanate, m-phenylene diisocyanate, etc.

Furthermore, since the isocyanate group reacts easily with water, it is preferable to use a blocked isocyanate compound in which the isocyanate group is shielded by a blocking agent or the like in terms of the pot-life of the paint. At this time, by heating in the drying step after coating the coating composition on the polyester film, the blocking agent is dissociated to expose the isocyanate group, and as a result, the crosslinking reaction proceeds.

The acrylic resin usable as the resin or the compound (B) is not particularly limited, but is preferably composed of alkyl methacrylate and/or alkyl acrylate.

As the alkyl methacrylate and/or the alkyl acrylate, it is preferable to use methacrylic acid, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, methacrylic acid Isobutyl, n-hexyl methacrylate, lauryl methacrylate, 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate, acrylic acid, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate ester, isobutyl acrylate, n-hexyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, hydroxypropyl acrylate, maleic acid, itaconic acid, acrylamide, N-hydroxy Methacrylamide, diacetoneacrylamide, etc. These can be used 1 type or 2 or more types.

In addition, the urethane resin that can be used as the resin or compound (B) is preferably a polyol compound and a polyisocyanate compound reacted by well-known urethane resin polymerization methods such as emulsion polymerization and suspension polymerization. And get the resin.

Examples of polyols include polyethylene glycol, polypropylene glycol, polyethylene-propylene glycol, polytetramethylene glycol, hexamethylene glycol, tetramethylene glycol, 1,5-pentanediol, alcohol, diethylene glycol, triethylene glycol, polycaprolactone, polyhexamethylene adipate, polyhexamethylene sebacate, polytetramethylene adipate, polytetramethylene Methyl sebacate, trimethylolpropane, trimethylolethane, pentaerythritol, polycarbonate diol, glycerin, etc.

As the polyisocyanate compound, for example, hexamethylene diisocyanate, diphenylmethane diisocyanate, toluene diisocyanate, isophorone diisocyanate, adducts of toluene diisocyanate and trimethylene propane, hexamethylene diisocyanate, Adducts of isocyanate and trimethylolethane, etc.

The silicone resin usable as the resin or the compound (B) may be a type mainly composed of a curable silicone resin or a modified silicone resin as a main component. As the type of curable silicone resin, any curing reaction type such as addition type, condensation type, ultraviolet curing type, electron beam curing type, solvent-free type, heat and ultraviolet curing type, etc. may be used. The modified silicone resin may be a modified silicone resin obtained by graft polymerization with organic resins such as epoxy resins, urethane resins, and alkyl resins.

The coating composition forming the coating layer of the biaxially oriented polyester film of the present invention is preferably in the range of 10/90 to 45/55, more preferably 15/85 ~ 45/55 range. By setting it as this range, the release agent (A) in a resin layer becomes sufficient quantity, and initial stage tape peeling force can be made favorable. Simultaneously with this, since the resin or compound (B) which changes easily by heating also becomes sufficient quantity, the peeling characteristic before and after heating can be made favorable.

In the coating layer (R1) layer of this invention, particle|grains can be contained in the range which does not affect the said Sp5%A (nm) of the said A surface.

When the thickness of the aforementioned R1 layer in the present invention is regarded as T _R1 (μm), T _R1 is preferably 0.01 or more and 1.00 or less. By setting the aforementioned T _R1 (μm) to 0.01 or more, the peeling function for the target member can be exhibited, and by setting it to 1.00 or less, uneven drying of the coating composition can be reduced, and local uneven formation of the coating layer can be suppressed. A more preferable range of the thickness T _R1 of the R1 layer is not less than 0.01 and not more than 0.30.

The method for forming the aforementioned R1 layer in the present invention is not particularly limited, but when using the aforementioned coating composition, an off-line coating method for coating after polyester film production or coating and drying during the polyester film production step can be used. Any of the in-line coating methods.

(object component provided on the aforementioned surface) ＜Ceramic paste＞ When using the biaxially oriented polyester film of the present invention as a film for a support formed by a green sheet in the step of manufacturing a laminated ceramic capacitor, it is preferable to coat the green sheet on the aforementioned surface of the release resin coating layer (R1). ceramic paste.

The raw material of the ceramics constituting the ceramic slurry is not particularly limited, and various dielectric materials can be used. For example, oxides made of metals such as titanium, aluminum, barium, lead, zirconium, silicon, and yttrium, barium titanate, Pb(Mg _1/3 , Nb _2/3 )O ₃ , Pb(Sm _{1 /2} , Nb _1/2 )O ₃ , Pb(Zn _1/3 , Nb _2/3 )O ₃ , PbThO ₃ , PbZrO ₃ , etc. These may be used alone or in combination of two or more.

As the binder resin constituting the ceramic slurry, polyurethane resin, urea resin, melamine resin, epoxy resin, vinyl acetate resin, acrylic resin, polyvinyl alcohol, polyvinyl butyral, etc. can be used. molecules etc. These may be used alone or in combination of two or more.

The solvent of the ceramic slurry may be water or an organic solvent without any problem. In the case of an organic solvent, toluene, ethanol, methyl ethyl ketone, isopropanol, γ-butyl lactone and the like can be used. These may be used alone or in combination of two or more. Moreover, a plasticizer, a dispersant, an antistatic agent, a surfactant, etc. can be added to ceramic slurry as needed.

(Manufacturing method of biaxially oriented polyester film) Next, an example will be given for the production method of the biaxially oriented polyester film of the present invention, but the present invention should not be construed as being limited to what is obtained from this example.

As a method for obtaining the polyester film used in the present invention, a common polymerization method can be used. For example, a dicarboxylic acid component such as terephthalic acid or an ester-forming derivative thereof and a diol component such as ethylene glycol or an ester-forming derivative thereof can be transesterified or esterified by a known method. After the reaction, it is obtained by carrying out a melt polymerization reaction. Also, if necessary, the polyester obtained by melt polymerization may be subjected to solid phase polymerization at a temperature lower than the melting point of the polyester.

The polyester film of the present invention can be obtained by known production methods. Specifically, the polyester film of the present invention can be processed into a thin sheet by heating and melting raw materials that are optionally dried in an extruder, extruded from a metal nozzle onto a cooled casting drum (melt casting) Law). As another method, it is also possible to dissolve the raw material in a solvent, extrude the solution from a metal port onto a support such as a casting drum or an endless belt to form a film, and then dry and remove the solvent from the film layer and process it into a Thin sheet method (solution casting method), etc.

When producing a biaxially oriented polyester film with more than two layers by melt casting, it is advisable to use an extruder to melt the raw materials of each layer for each layer constituting the biaxially oriented polyester film, so that these are placed in the extrusion device The confluence device between the metal nozzle is laminated in a molten state, guided to the metal nozzle, and then extruded from the metal nozzle onto the casting drum to be processed into a thin sheet (co-extrusion method). The laminated sheet is electrostatically adhered to the casting drum whose surface temperature has been cooled to 20°C to 60°C, cooled and solidified to produce an unstretched film. Since the surface temperature of the casting drum is set at 20°C or higher, the crystalline polyester portion on the surface of the unstretched film can be increased, and the effect of forming fine protrusions after stretching by plasma surface treatment caused by atmospheric pressure glow discharge can be obtained. In addition, since the surface temperature of the casting drum is set to 60°C or lower, sticking of the unstretched film to the casting drum can be suppressed, and an unstretched film with little thickness unevenness in the film traveling direction can be obtained. The more preferable range of the surface temperature of the casting drum is not less than 25°C and not more than 55°C.

Next, surface treatment such as plasma surface treatment by atmospheric pressure glow discharge is applied to the unstretched film obtained here. Such surface treatment can be carried out immediately after obtaining the unstretched film, and can also be carried out after stretching in the traveling direction of the film (hereinafter also referred to as the longitudinal direction). However, it is preferable from the viewpoint of promoting the formation of the aforementioned protrusions. In addition, the surface to be subjected to surface treatment may be either a surface in contact with the casting drum (drum surface) or a surface not in contact with the casting drum (non-drum surface).

(sequential biaxial extension) There are no particular restrictions on the stretching conditions when biaxially stretching the unstretched film, but when the polyester film of the present invention is made of polyester as the main component, it is more preferable to stretch the unstretched film in the longitudinal direction. Lead to the group of rollers heated to 70°C or higher, extend in the longitudinal direction (longitudinal direction, that is, the traveling direction of the film), and cool with the group of rollers set at a temperature of not less than 20°C and not more than 50°C. The lower limit of the heating roller temperature during stretching in the longitudinal direction is not particularly limited as long as the stretchability of the sheet is not impaired, but it is preferably higher than the glass transition temperature of the polyester resin used. Moreover, the preferable range of the stretching ratio in a longitudinal direction is 3 times or more and 5 times or less. A more preferable range is not less than 3 times and not more than 4 times. When the stretching ratio in the longitudinal direction is 3 times or more, oriented crystallization progresses and the film strength can be improved. On the other hand, since the stretching ratio is set to 5 times or less, it is possible to suppress excessive alignment and crystallization of the polyester resin accompanying stretching, resulting in brittleness and cracking during film formation.

Regarding the extension in the direction (width direction) at right angles to the longitudinal direction, it is preferable to guide the film to a tenter while holding both ends of the film with clips, and to heat it to a temperature of 70°C or higher and 160°C or lower. , Stretching 3 times to 5 times in the direction perpendicular to the longitudinal direction (width direction), and then heat-treating the stretched film to stabilize the internal alignment structure. Regarding the heat history temperature of the film during heat treatment, it can be confirmed by the temperature of the tiny endothermic peak (also called Tmeta) that appears just below the melting point temperature measured by the differential scanning calorimeter (DSC) described later, but as a tenter device The set temperature is preferably set so that the maximum temperature in the tenter is 200°C to 250°C when polyester (melting point 255°C) is used as the main component, and it is preferably set when other thermoplastic resins are used as the main component The melting point of the resin is above -55°C and the melting point of the resin is below -5°C. Since the heat treatment temperature is set above 200°C, the dimensional stability of the biaxially oriented polyester film can be improved, and since the heat treatment temperature is set below 250°C, the film cracking accompanying the melting of the polyester film can be suppressed, and the productivity well made. A more preferable range is not less than 220°C and not more than 245°C.

The range of Tmeta, which represents the heat history temperature of the film during heat treatment, is preferably 190°C or higher and 245°C or lower for the above-mentioned reason when the polyester resin is used as the main component. A more preferable range is not less than 210°C and not more than 240°C.

In addition, for the purpose of imparting dimensional stability after the heat treatment, relaxation treatment (relaxation treatment) may be performed in the range of 1% to 6%. Since the relaxation treatment is set to 1% or more, the dimensional stability of the biaxially oriented polyester film can be improved when used in a high temperature environment, and since it is set to 6% or less, a moderate tension is continuously applied to the biaxially oriented polyester film, Prevents thickness unevenness from worsening.

The elongation ratio is set to 3 times to 5 times in the longitudinal direction and the width direction, respectively, and the area ratio (stretching ratio in the longitudinal direction×stretching ratio in the width direction) is preferably 9 times to 22 times, more preferably 9 or more 20 times or less. Since the area ratio is set to 9 times or more, the molecular alignment of the obtained biaxially oriented polyester film can be promoted to improve durability, and since the area ratio is set to 22 times or less, cracks during stretching can be suppressed.

(Manufacturing method of biaxially oriented polyester film) An example is given of a production method of providing a release layer on the biaxially aligned polyester film obtained through the above-mentioned production steps by off-line coating, but the present invention should not be construed as being limited to what was obtained in this example.

After the coating composition is coated on the biaxially aligned polyester film of the present invention, it is dried at 60° C. to 110° C. to form a coating layer. The drying time is not particularly limited, but by setting it to 30 seconds or less, productivity in the coating step can be improved. As the coating method of the aforementioned paint composition, well-known coating methods can be used, for example, roll coating methods such as gravure coating or reverse gravure coating, bar coating methods using wire bars, die coating methods, lip coating methods, and spray coating methods. , Air knife coating method, etc.

[Evaluation method of characteristics] A. Evaluation of Scanning White Interference Microscope (VertScan) Sampling of 6 cm x 6 cm was carried out from a biaxially aligned polyester film. For each sample, a scanning white interference microscope (device: Hitachi High-Tech Science Co., Ltd. "VertScan" (registered trademark) VS1540) was used, and a 10-fold objective lens was used to obtain Measurement area 561 μm×561 μm The aforementioned surface in the biaxially aligned polyester film was measured. The sample setting was performed by placing the sample on a stage so that the measurement Y-axis became the longitudinal direction of the sample film (the direction in which the film was wound up). In addition, in the case of a sample whose longitudinal direction is unknown, the measurement is performed so that the Y-axis becomes any one direction of the sample film, and then the measurement is performed in the direction rotated by 120 degrees, and then the measurement is performed in the direction rotated by 120 degrees. The average of the respective measurement results was regarded as the number of protrusions that the sample had. In addition, the sample film to be measured is sandwiched between two metal frames equipped with rubber pads, and the film in the frame is made into a tense state (the state after removing the slack or curl of the sample), and the surface of the sample is measured.

The obtained microscopic image was subjected to image processing with the surface analysis software VS-Viewer Version 10.0.3.0 built into the microscope under the following conditions to obtain the arithmetic mean surface roughness and the number of protrusions at each height.

(image processing conditions) Image processing is performed in the following order. ・Interpolation processing : Fully interpolated ・Filter processing : Median (3×3 pixels) ・Face Correction : 4 times.

(i) The upper 5% of the maximum protrusion height (Sp5%A and Sp5%B) Regarding the above-mentioned surface (A surface) of the biaxially oriented polyester film, use a scanning white interference microscope to measure 100 fields of view, and for each measurement image that has been subjected to the above-mentioned image processing, use the "parameter sheet" window in the surface analysis software. The "Peak [μm]" displayed on the "ISO parameter" label is converted into a value in nm, and the maximum protrusion height Sp (nm) of each 100 field of view is calculated, and the upper 5% value (the case of 100 field of view is the fifth largest value) ) is defined as the upper 5% value Sp5%A (nm) of the maximum protrusion height of the aforementioned surface (A surface). Similarly, for the above-mentioned surface B, a scanning white interference microscope measurement is performed, and for each measurement image that has been subjected to the above-mentioned image processing, the "Peak[ μm]” into nm units, calculate the maximum protrusion height Sp (nm) of each 100 field of view, and set the upper 5% value (the fifth largest value in the case of 100 field of view) as the maximum protrusion height of the aforementioned B surface Upper 5% value Sp5%B(nm). (ISO parameter analysis conditions) The ISO parameter analysis process is performed under the following conditions. ・S-Filter : Automatic ・Regular probability paper Number of divisions : 300 Upper limit of calculation range: 3.000 Calculation range lower limit: -3.000 ・Parameters : Only select "Height Parameters" ・Output: Select "Parameter List" (parameter form output) Select "Height Parameters" in the "ISO Parameters" window displayed through the above-mentioned ISO parameter analysis, perform "Add to Parameter Sheet", and add "Peak [μm]" displayed in the "ISO Parameters" tab of the "Parameter Sheet" window The values were converted into nm units and used.

(ii) The number of protrusions with a height of 80nm or more (N _80nm A) After the microscope image observation and image processing of the above-mentioned surface (A surface) are performed in the same way as in the above (i), use the surface analysis software built in the microscope VS-Viewer Version 10.0.3.0 performs particle analysis processing under the following conditions, and displays the number of particles detected on the "Particle Analysis" screen detected at a height threshold of 80nm (R _80nm , height threshold setting value: 0.08μm) (piece) was divided by the measurement area (561 μm×561 μm) to obtain the number of protrusions (piece/mm ² ) having a height of 80 nm or more. (Particle Analysis Conditions) The protrusion analysis process was performed under the following conditions.・Analysis type: _Protrusion analysis ・Image correction: None : -10000μm≦h≦10000μm Longest Diameter: -10000μm≦d≦10000μm Volume: V≧0.0000μm ³ Aspect Ratio: r≧0.0000 ・Histogram: Number of divisions 50 Perform the same operation on all 100 fields of view measured. The average value thereof was set as the number N _80nm A (number/mm ² ) of protrusions having a height of 80 nm or more on the surface A of the sample. (Reference height: zero surface (average surface)) As the zero surface (average surface) in the above-mentioned reference height setting, the measurement image (561μm×561μm) obtained by observing the microscope image by the above-mentioned method and applying the above-mentioned image processing In , the plane of the average value (Ave) of the heights automatically obtained by the following formula is used.

・lx: The length of the range in the X direction in each measurement image that has undergone image processing ・ly: The length of the range in the Y direction in each measurement image that has undergone image processing (iii) The number of protrusions with a height of 10nm or more (N _10nm A) in each image point (x, y) in the processed measurement image Microscopic image of the above-mentioned surface (A surface) applied in the same way as in (i) above After observation and image processing, use the built-in surface analysis software VS-Viewer Version 10.0.3.0 of the microscope to perform particle analysis processing under the following conditions, and set the height threshold of 10nm (R _10nm , height threshold setting value: 0.01 µm) The number of particles (pieces) displayed on the "Particle Analysis" screen detected was divided by the measurement area (561 μm×561 μm) to obtain the number of protrusions with a height of 10 nm or more (pieces/mm ² ). The same operation was performed on all the measured 100 fields of view, and the average value thereof was defined as the number N _10nm A (number/mm ² ) of protrusions having a height of 10 nm or more on the surface A of the sample.

B. Water Contact Angle (CaR) After placing the biaxially oriented polyester film of the present invention in an environment with a room temperature of 23° C. and a humidity of 65% for 24 hours, use a contact angle meter CA-D type (manufactured by Kyowa Interface Science (Stock) Co., Ltd.) in this environment, according to JIS K6768 measures the contact angle of the aforementioned surface (side A) to water. The average value of 3 measurements excluding the maximum value and the minimum value of 5 measurements was set as the water contact angle CaR (°) of the surface A described above.

C. Film thickness (i) Full thickness The thickness of the entire layer of the biaxially oriented polyester film was measured at any five locations in a state where 10 films were stacked in accordance with JIS K7130 (1992) A-2 method using a dial gauge. The average value was divided by 10 to obtain the total film thickness T (μm).

(ii) Lamination thickness (T _P1 , T _P2 ) In a direction parallel to the film width direction, a section of the biaxially aligned polyester film was cut out with a microtome. The cross-section was observed with a scanning electron microscope at a magnification of 5,000 to 20,000 times, and the thickness ratio of each layer of the laminate was determined. The thickness of each layer is calculated from the calculated lamination ratio and the total film thickness obtained in the above item (i).

(iii) Thickness (T _R1 ) of coating layer (R1) Ruthenium tetroxide (RuO ₄ ) and/or osmium tetroxide (OsO ₄ ) were used to dye the biaxially aligned polyester film. Freeze the biaxially oriented polyester film, cut it along the thickness direction of the film, and obtain 10 points (10 pieces) of ultrathin section samples for observation of the cross section of the resin layer. The cross-section of each sample was observed at a magnification of 10,000 to 1,000,000 with a TEM (transmission electron microscope: H7100FA manufactured by Hitachi, Ltd.), and a cross-sectional photograph was obtained. The measured value of the thickness of the release resin coating layer (R1 layer) which has the said surface in 10 points (10 pieces) was averaged, and it was set as the thickness T _R1 (micrometer) of the release resin coating layer.

(iv) Thickness unevenness ΔT in width direction of film roll Using a contact-type continuous thickness meter (KG601B manufactured by ANRITSU Co., Ltd.), measurement of the entire width in the width direction of the film roll of the biaxially oriented polyester film was carried out. In the obtained film thickness, according to the following formula (1), the thickness unevenness obtained by subtracting the minimum value (T _MIN ) from the maximum value (T _MAX ) is divided by the average value (T _AVE ), and the percentage unit conversion is performed. Find ΔT(%). Measurements were performed three times at every 15 m in the film unwinding direction, and ΔT was obtained for each measurement, and the maximum value thereof was defined as the thickness unevenness ΔT (%) of the biaxially oriented polyester film. ΔT(%)=100×(T _MAX -T _MIN )/T _AVE・・・Formula (1) The width direction of the aforementioned film roll refers to the film plane of the biaxially oriented polyester film of the present invention, and the film The unwinding direction is a vertical direction. When a biaxially oriented polyester film of a specific size is cut out and the unwinding direction is unknown, thickness unevenness is measured for the specific direction and the direction inclined by 90° in the film plane from the aforementioned measurement direction. The maximum value of them was set as the thickness unevenness ΔT(%) of the biaxially oriented polyester film.

Similarly, when it is difficult to measure 3 times per 15m in the unwinding direction after cutting out a biaxially oriented polyester film of a specific size, measure the thickness unevenness in the width direction at the third equal point of the full width in the unwinding direction , let their maximum value be the thickness unevenness ΔT(%) of the biaxially oriented polyester film.

D. Tape peel force (FA) The tape peel force was measured as follows. First, stick an acrylic polyester adhesive tape (manufactured by Nitto Denko Co., Ltd., Nitto 31B tape, 19 mm wide) on the coating layer of the biaxially aligned polyester film of the present invention, and move a 2 kgf roller back and forth once from above. , made of adhesive tape lamination film. Then, the adhesive tape laminated film was left to stand for 24 hours in an environment of 25°C and 65%RH, and then was tested at a peeling angle of 180° and a tensile speed of 300mm using a universal testing machine "Autograph AG-1S" manufactured by Shimadzu Co., Ltd. Peel force (N/19mm) was measured per minute. The average value of the peeling force of 5 to 10 sec was calculated from the graph of the peeling force (N/19mm) obtained by the measurement-test time (sec). The same measurement was performed 5 times, and the average of the 3 times after removing the maximum value and the minimum value was regarded as the peeling force FA (mN/19mm) of the laminated film.

E. Static friction coefficient (μs) After adjusting the humidity of the biaxially oriented polyester film of the present invention to 23°C and 65%RH, cut out two strips with a width of 75 mm and a length of 100 mm as samples in such a way that the direction of the film production line becomes the length. The coefficient measurement device (type ST-200, manufactured by TECHNO NEEDS Co., Ltd.) was used for measurement in an environment of 23° C. and 65% RH. On the measurement table of the device, a long sample is set such that the stretching direction of the device is the longitudinal direction of the long sample, and the above-mentioned surface side is set and fixed. Put another strip-shaped sample on it with the above-mentioned surface as the upper side and the stretching direction as the longitudinal direction, make the above-mentioned surface and its opposite surface contact, and at the same time fix the end of the sample to the U meter for weighted detection of this device . Then let the film stand still, place a Teflon (registered trademark) sheet with a sample contact surface of 6.5cm x 6.5cm on it, place a weighing weight with a load of 200g to make the samples adhere to each other, and then measure the film on the upper side under the following conditions Static coefficient of friction when stretched down. The measurement was performed 10 times, and the average value of the 6 measured values after excluding the upper 2 points and the lower 2 points was used as the coefficient of static friction (μs). Measuring distance: 12mm Measuring speed: 210mm/min.

F. Polymer properties (i) Intrinsic viscosity (IV) Dissolve the test sample (polyester resin (raw material), master pellet, or only the P1 layer) in 100ml o-chlorophenol (solution concentration C( Measure sample weight/solution volume) = 1.2g/100ml), use Aoshihua viscometer to measure the viscosity of the solution at 25°C. Also, the viscosity of the solvent was measured in the same manner. Using the obtained solution viscosity and solvent viscosity, calculate [η] according to the following formula (2), and use the obtained value as the intrinsic viscosity (IV). ηsp/C=[η]+K[η] ²・C・・・(2) (here, ηsp=(solution viscosity/solvent viscosity)-1, K is the Huggins constant (set to 0.343)). In addition, when insoluble matter such as inorganic particles exists in the solution in which the measurement sample is dissolved, the following method is used for measurement. (1-1) The measurement sample was dissolved in 100 mL of o-chlorophenol to prepare a solution having a concentration higher than 1.2 g/100 mL. Here, let the weight of the measurement sample for o-chlorophenol be the measurement sample weight. (1-2) Next, the solution containing the insoluble matter is filtered, and the weight measurement of the insoluble matter and the volume measurement of the filtered filtrate are performed. (1-3) Add o-chlorophenol to the filtrate after filtration, as (measurement sample weight (g)-weight of insoluble matter (g))/(volume of filtered filtrate (mL)+additional o-chlorophenol Volume (mL)) was adjusted so that it became 1.2g/100mL. (For example, when making a thick solution with a measurement sample weight of 2.0g/solution volume of 100mL, the weight of insoluble matter when filtering the solution is 0.2g, and the volume of the filtrate after filtration is 99mL, add 51mL of o-chlorophenol to Adjustment is carried out. ((2.0g-0.2g)/(99mL+51mL)=1.2g/ 100mL)) (1-4) Use the solution obtained in (1-3) to measure at 25°C with an Oswald viscometer For the viscosity, [η] is calculated according to the above formula (3) using the obtained solution viscosity and solvent viscosity, and the obtained value is taken as the intrinsic viscosity (IV).

(ii) Amount of terminal carboxyl group (unit: eq/t, recorded as COOH amount in the table) Determination was performed by the method of Maulice. (Document M. J. Maulice, F. Huizinga, Anal. Chem. Acta, 22, 363 (1960)). That is, 0.5 g of the measurement sample (polyester (raw material) or polyester film after separating only the P1 layer) was weighed with an accuracy within 0.001 g. To this sample, 50 ml of a solvent mixed at a mass ratio of o-cresol/chloroform of 7/3 was added, and it was dissolved by heating and stirring for 20 minutes while heating to an internal temperature of 90°C. Also, only the mixed solvent was used as a blank solution, and it was heated separately in the same manner. Cool the solution to room temperature, and titrate with a 1/50N potassium hydroxide methanol solution using a potentiometric titration device. Also, titration was performed in the same manner for a blank solution in which only a solvent was mixed. Let the value calculated by the following formula be the amount of terminal carboxyl groups of a measurement sample. Terminal carboxyl group amount (equivalent/t)={(V1-V0)×N×f}×1000/S Here, V1 is the titrant volume (mL) of the sample solution, V0 is the titrant volume (mL) of the blank solution, N is the equivalent concentration (N) of the titrant, f is the coefficient of the titrant, and S is the polyester composition The mass of the object (g).

G. Contains particle evaluation (i) Average particle size Regarding the biaxially oriented polyester film of the present invention, use a microtome to cut in a direction perpendicular to the surface to make small pieces, and use an electric field emission scanning electron microscope JSM-6700F (manufactured by Japan Electronics Co., Ltd.) for its cross section. Observe the P1 layer, P2 layer or P3 layer with a magnification of 10,000 to 30,000 times and take pictures. The particle size distribution of the particles present in the P1 layer, P2 layer, or P3 layer was obtained from the cross-sectional photos using the image analysis software Image-Pro Plus (Japan ROPER Co., Ltd.). The cross-sectional photos are selected from different arbitrary measurement fields, and the circle-equivalent diameters of more than 400 particles randomly selected from the cross-sectional photos are measured to obtain the volume-based average particle diameter. By the constituent element analysis of the following particles, when two or more kinds of particles are contained, the circle-equivalent diameters of 200 or more particles are measured for each particle, and the average particle diameter is obtained from the average value of the volume-based circle-equivalent diameters.

(ii) Particle size distribution analysis The volume-based particle size distribution analysis was performed on the particle diameter obtained by the method described in (i) above. Here, the particle diameter serving as the abscissa in the volume-based particle size distribution is represented by a rank at every 10 nm interval with 0 nm as the initial point. From the particle size distribution diagram of the obtained particles, the particle diameter showing the largest peak was read.

(iii) Maximum particle size (D _P1 , D _P2 ) Regarding the particle size obtained by the method described in (i) above, the maximum value is defined as the maximum particle size contained in the layer.

(iv) Particle content Put the P1 layer or P2 layer part of the biaxially oriented polyester film of the present invention into 200ml of 1N-KOH methanol solution and heat to reflux to dissolve the polymer. Add 200ml of water to the solution after dissolution, and then use a centrifuge to settle the particles, and remove the supernatant. Water was further added to the particles for washing and centrifugation, and this was repeated twice. The particles obtained in this way were dried, and their mass was weighed to calculate the content (mass %) of the particles contained in each layer. When the added particles include organic particles, select a solvent that dissolves the polymer but does not dissolve the organic particles, dissolves the polymer under reflux without overheating, centrifuges the particles, and calculates the content (mass %) of the particles.

[Evaluation method of use characteristics] H. Surface defects during step handling The biaxially oriented polyester film of the present invention is formed into a film at a film forming speed of 100 m/min or more, and 10 continuous film rolls of 5000 m are collected. The obtained 10 film rolls were unwound, and the defect of the surface damage in the surface (the said surface) of the release resin coating layer was evaluated as follows. AA: Among the 10 rolls, 0 rolls had a surface damage defect.

A: Among the 10 rolls, the number of rolls with surface damage defect is 1 or more and 2 or less.

B: Among the 10 reels, 3 or more and 4 or less reels had surface damage defects. C: Among the 10 reels, 5 or more and 6 or less reels had surface damage defects. D: Out of 10 reels, 7 or more reels had surface damage defects. Among the surface defects during step handling, A to C are good, and AA is the most excellent.

I. Surface machinability during step handling The surface machinability during the process of conveyance was evaluated by the amount of cutting powder attached to the single blade by using the following tape running tester and single-blade test. First, a tape with a width of 12.65 mm and a length of 25 cm was cut out from a biaxially oriented polyester film having a coating layer, and those subjected to humidity conditioning for one day in an environment of 23° C. and 65% RH were used as samples. The tape running tester SFT-700 (manufactured by Yokohama System Research Institute Co., Ltd.) is equipped with the following device configuration. Under the environment of 23°C and 65%RH, a load of 300g is applied to the edge of the tape-shaped sample, and the load is applied in the longitudinal direction. Under tension, make it advance 10cm at a speed of 3.33cm/sec. At this time, the sample was advanced while pressing the following carbon steel razor by 1 mm against the surface (the surface) of the release resin coating layer of the biaxially oriented polyester film having the coating layer. Then, using an optical microscope, the surface side of the single-edged blade through which the film passes was observed at a magnification of 200 times, and the accumulation height of the chips deposited on the blade peak was determined. Cut at any 5 points in the range of 12.65 mm where the single-edged film passes, observe the accumulation height, and evaluate the average value as the surface machinability of the sample at the time of step transportation. A: The accumulation height of chips is 20 μm or less. B: The accumulation height of chips exceeds 20 μm and is 30 μm or less. C: The accumulation height of chips exceeds 30 μm and is 40 μm or less. D: The accumulation height of chips exceeds 40 μm. In surface machinability during step handling, A to C are good, and A is the most excellent. (device configuration) Guide piece diameter: 6mmΦ Guide material: SUS27 (surface roughness 0.2S) Wrapping angle: 90° Single edge: carbon steel razor (manufactured by FEATHER Safety Razor Co., Ltd., FAS-10) Single blade installation direction: The width direction of the single blade is parallel to the width direction of the tape, and the angle formed by the single blade and the surface of the release resin coating layer is set so that it becomes 90°. Single-blade pushing length: press 1mm along the direction of sample thickness (measurement conditions) Travel distance: 10cm Travel speed: 3.33cm/sec.

J. Winding Offset The biaxially oriented polyester film of the present invention is formed into a film at a film forming speed of 100 m/min or more, and taken 10 times of continuous roll winding of 5000 m. The occurrence of winding misalignment of the obtained 10 film rolls was evaluated as follows.

A: Among the 10 reels, there were less than 2 reels with winding deviation. B: Among the 10 reels, there are 3 or more and 4 or less reels with winding deviation. C: Among the 10 reels, 5 or more and 6 or less reels with misaligned winding occurred. D: Among the 10 reels, there were 7 or more reels with misaligned winding. In winding deviation, A to C are good, among which A is the most excellent. In step transportability, A to C are good, and among them, A is the most excellent.

K. Convoluted wrinkles The biaxially oriented polyester film of the present invention is formed into a film at a film forming speed of 100 m/min or more, and taken 10 times by continuous roll winding of 5000 m. The occurrence of winding wrinkles of the obtained 10 film rolls was evaluated as follows.

A: Among the 10 reels, the number of reels having winding wrinkles was 2 or less. B: Among the 10 reels, 3 or more and 4 or less reels have winding wrinkles. C: Among the 10 reels, 5 or more and 6 or less reels have winding wrinkles. D: Among the 10 reels, 7 or more reels had winding wrinkles. Among the convoluted wrinkles, A to C are good, and among them, A is the most excellent.

L. Coating and peeling evaluation of green sheet (i) Preparation of ceramic slurry In 100 parts by mass of barium titanate (trade name HPBT-1 manufactured by Fuji Titanium Industry Co., Ltd.), 10 parts by mass of polyvinyl butyral (trade name BL-1 manufactured by Sekisui Chemical Co., Ltd.), 5 parts by mass of Dibutyl phthalate and 60 parts by mass of toluene-ethanol (mass ratio 30:30), add glass beads with a number average particle diameter of 2 mm, mix and disperse them with a jet mill for 20 hours, and then filter to adjust Pasty ceramic slurry.

(ii) Green flake formation The obtained ceramic slurry was coated on the A-side of the biaxially aligned polyester film of the present invention with a die coater so that the final thickness would be 0.7 μm, and dried to form a green sheet.

(iii) Coatability of ceramic slurry Formation of the green sheet using the ceramic slurry shown in item (ii) above was performed 10 times, and the occurrence of cracks was visually evaluated, and the applicability of the ceramic slurry was evaluated from the number of occurrences.

A: Cracks occurred 0 times out of 10 times. B: In 10 times, cracking occurred 1 time or more and 3 times or less. C: Cracks occurred 4 or more times and 5 or less out of 10 times. D: Cracks occurred 6 or more times out of 10 times. In the applicability of ceramic slurry, A to C are good, and A is the most excellent.

(iv) Detachability of green sheet Using a die coater, the ceramic slurry mixed in the same manner as in (ii) above was applied to the surface of the biaxially aligned polyester film of the present invention so that the final thickness would be 0.7 μm, and dried to form a raw material. Embryo flakes. On the green sheet of the green sheet biaxially aligned polyester film, acrylic polyester adhesive tape (manufactured by Nitto Denko Co., Ltd., Nitto 31B tape, 19 mm width) was attached as a support body, and a universal tester made by Shimadzu Co., Ltd. was used. The peeling force (mN/19mm) was measured at a peeling angle of 180° and a tensile speed of 300mm/min using the machine "Autograph AG-1S". From the graph of the measured peel force (mN/19mm)-test time (sec), calculate the average value of the peel force for 5 to 10 sec. This measurement was performed 5 times, and the average of the 3 times excluding the maximum value and the minimum value was defined as the peeling force (mN/19mm) of the biaxially oriented polyester film, and the peeling force of the green sheet was evaluated. A: The peeling force of the green sheet is not less than 5mN/19mm and not more than 20mN/19mm B: The peeling force of the green sheet is greater than 20mN/19mm and less than 30mN/19mm C: The peeling force of the green sheet is greater than 30mN/19mm and less than 50mN/19mm D: The peeling force of the green sheet is greater than 50 mN/19 mm. In the peeling force of the green sheet, A to C are good, and A is the most excellent.

(v) Sheet breakage of green sheet With respect to the 5 samples used for the measurement of the peeling force in the above item (iv), and regarding the green sheet peeled from the biaxially aligned polyester film, the presence or absence of sheet cracking was confirmed, and the green sheet was evaluated for chip cracking. A: No cracking of the flakes can be seen in 5 pieces B: Sheet cracking was observed in 1 of 5 sheets C: Flake cracking was seen in 2 out of 5 pieces D: Sheet cracking was observed in 3 or more out of 5 sheets In the flake breakage of the green flakes, A to C are good, and A is the most excellent.

(vi) Surface defects of the green sheet after peeling Regarding the peeled surface (the surface in contact with the release resin coating layer) of the green sheet peeled from the aforementioned three biaxially oriented polyester films used to obtain the average value of the peeling force in item (iv), use A scanning electron microscope (SEM) was used to observe at 5000 magnifications to confirm the presence or absence of surface defects with an equivalent circle diameter of 1 μm or more and a circle equivalent average diameter of 0.5 μm or more, and to evaluate the surface defects of the green sheet after peeling off. AA: No surface defects with an average diameter of 0.5 μm or more can be seen in the 3 pieces A: No surface defects with a circular equivalent average diameter of 1.0 μm or more can be seen in any of the 3 pieces B: 1 piece out of 3 pieces has a surface defect with a circle equivalent average diameter of 1.0 μm or more C: 2 out of 3 pieces saw surface defects with a circle equivalent average diameter of 1.0 μm or more D: Surface defects with a circle equivalent average diameter of 1.0 μm or more can be seen in all 3 pieces Among the surface defects of the green sheet after peeling, A to C are good, and AA is the most excellent. [Example]

Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited thereto.

[Manufacture of PET-1] To dimethyl terephthalate (DMT), add 1.9 mol of ethylene glycol to 1 mol of DMT and 0.05 parts by weight of magnesium acetate-tetrahydrate per 100 parts by weight of DMT , 0.015 parts by weight of phosphoric acid, for heating transesterification. Next, 0.025 parts by weight of antimony trioxide was added, the temperature was raised, and polycondensation was carried out under vacuum to obtain polyester pellets substantially free of particles. The obtained melt-polymerized PET had a glass transition temperature of 81°C, a melting point of 255°C and an intrinsic viscosity of 0.55.

Then, the obtained polyester pellets were dried at 160° C. for 6 hours and crystallized, and then subjected to solid-phase polymerization at 220° C. and a vacuum degree of 0.3 Torr for 8 hours to obtain solid-phase polymerized PET. The obtained solid phase polymerized PET had a glass transition temperature of 81° C., a melting point of 255° C. and an intrinsic viscosity of 0.63.

[Manufacturing of PET-2] In Example 1 described later, the constituent resin of the intermediate layer (P3 layer) was only PET-1, and the biaxially oriented polyester film formed in the same manner as in Example 1 was pulverized, and then dried at 280°C. It was remelted and extruded to obtain recycled PET-2. The obtained recycled raw material PET-2 had a glass transition temperature of 81°C, a melting point of 255°C, and an intrinsic viscosity of 0.60. [Manufacturing of PET-3] Except in Example 1 described later, the constituent resin of the intermediate layer (P3 layer) is only PET-1, and the constituent resin of the P2 layer is contained so that the silica-6 described later is 1.0% relative to the entire P2 layer. Except that, film formation was performed in the same manner as in Example 1, and a coating layer was provided by in-line coating using a coating composition C described later to obtain a biaxially oriented polyester film having a coating layer. On the surface of the coating layer of the obtained biaxially oriented polyester film with a coating layer (the above-mentioned A side), according to the above-mentioned method of "coating and peeling evaluation of the green sheet", after forming and peeling the green sheet, use alkaline The coating layer of the biaxially oriented polyester film was removed from the solution, and only the remaining biaxially oriented polyester film was pulverized, remelted at 280° C. and extruded to obtain PET-3 as a recycled raw material. The obtained recycled raw material PET-3 had a glass transition temperature of 81°C, a melting point of 255°C, and an intrinsic viscosity of 0.59.

[Manufacturing of MB-A] During the polymerization of PET-1 in the preceding paragraph, silicon dioxide particles (silicon dioxide-1) with an average primary particle diameter of 65 nm dispersed in ethylene glycol were added so that the amount added was 1% by mass relative to PET, Obtain PET base masterbatch MB-A. The obtained melt-polymerized MB-A had a glass transition temperature of 81°C, a melting point of 255°C and an intrinsic viscosity of 0.62. [Manufacture of MB-B～G] MB-B to G were obtained similarly to MB-A except having changed the kind of the added silica particle as described in Table 1. The properties of the obtained MB-B-G are shown in Table 1.

[Table 1] Masterbatch Pellet Composition Shot characteristics Constituent resin Particle content (mass%) particle Average primary particle size when dispersed in ethylene glycol (nm) Glass transition temperature (°C) Melting point (°C) IV (dl/g) MB-A PET 1.0 Silica-1 65 81 255 0.62 MB-B PET 1.0 Silica-2 310 81 255 0.62 MB-C PET 1.0 Silica-3 450 81 255 0.62 MB-D PET 1.0 Silica-4 820 81 255 0.62 MB-E PET 1.0 Silica-5 110 81 255 0.62 MB-F PET 1.0 Silica-6 1000 81 255 0.62 MB-G PET 1.0 Alumina-1 25 81 255 0.62

[Release agent (A)] ・Long-chain alkyl group-containing resin (a-1) 2-Hydroxyethyl acrylate (HEA) (manufactured by Kanto Chemical Co., Ltd.), α,α'-azobisisobutyronitrile (AIBN ) (manufactured by Kanto Chemical Co., Ltd.), cumyl dithiobenzoate (CDB) as a RAFT agent, and toluene as a solvent in the weight of HEA/CDB/AIBN/toluene=0.35/0.03/0.007/2.27 (g) join. Next, the mixed solution in the ampoule was degassed twice by the freezing degassing method, and then the ampoule was sealed and heated in an oil bath at 100° C. for 18 hours to obtain a reaction solution containing a polymer.

In the reaction solution in the ampoule, add behenyl acrylate, AIBN as a polymerization initiator and toluene as a solvent with the weight (g) of behenyl acrylate/AIBN/toluene=4.65/0.003/1.3, After freezing and degassing twice, the ampoule was sealed and heated at 100° C. for 48 hours. Then, the polymerization solution was dropped into 20 times the mass of hexane, and stirred to deposit a solid. The obtained solid was taken out by filtration, and vacuum-dried overnight at 40° C. to obtain a long-chain alkyl group-containing resin (a long-chain alkyl group-containing resin of a block copolymer having an alkyl group having 22 carbon atoms) (a-1).

The long-chain alkyl group-containing resin (a-1) was emulsified as follows to obtain a water-based resin emulsion. Add 375g of water to a homogenizer with a capacity of 1L, add 45g of polyoxyethylene nonylphenyl ether, 30g of polyoxyethylene polyoxypropylene glycol, 200g of long-chain alkyl-containing resin a1, and 150g of toluene, heated to 70°C, and stirred evenly. This mixed solution was transferred to a pressurized homogenizer, and after emulsification, the toluene was distilled off under reduced pressure while warming. ・Polyether modified polydimethylsiloxane Polyether-modified polydimethylsiloxane (TSF4446; solid content concentration 100%) made by MOMENTIVE was used.

[Resin or compound (B)] ・Silicone resin (b-1): Shin-Etsu Chemical Co., Ltd.'s polysiloxane-containing paint model X-62-7655, Shin-Etsu Chemical Co., Ltd.'s polysiloxane-containing paint model X-62-7622 and Shin-Etsu Chemical (Co., Ltd.) catalyst model CAT-7605 was mixed at a mass ratio of 95:5:1.

・Fluorine-containing silicone resin (b-2): Silicone-containing varnish model KR-400 manufactured by Shin-Etsu Silicone Co., Ltd. was used.

・Acrylic resin (b-3) In a stainless steel reaction vessel, methyl methacrylate (α), hydroxyethyl methacrylate (β), urethane acrylate oligomer (manufactured by Negami Industry Co., Ltd., Artresin (registered trademark) UN -3320HA, the number of acryl groups is 6) (γ) is added in a mass ratio of (α)/(β)/(γ)=94/1/5, relative to the total of (α)～(γ) 100 mass 2 parts by mass of sodium dodecylbenzenesulfonate as an emulsifier was added and stirred to prepare a mixed solution 1. Next, prepare a reaction device equipped with a stirrer, a reflux cooling tube, a thermometer, and a dropping funnel. 60 parts by mass of the above mixed solution 1, 200 parts by mass of isopropanol, and 5 parts by mass of potassium persulfate as a polymerization initiator were added to the reaction device, heated to 60° C., and mixed solution 2 was prepared. Mixed solution 2 was kept under heating at 60°C for 20 minutes. Next, a mixed liquid 3 composed of 40 parts by mass of the mixed liquid 1, 50 parts by mass of isopropyl alcohol, and 5 parts by mass of potassium persulfate was prepared. Next, using the dropping funnel, the mixed solution 3 was dropped onto the mixed solution 2 over 2 hours to prepare the mixed solution 4 . Then, the mixed liquid 4 was maintained for 2 hours in a state heated to 60°C. After the obtained mixed solution 4 is cooled to below 50°C, it is moved to a container equipped with a stirrer and a decompression device. Add 60 parts by mass of 25% ammonia water and 900 parts by mass of pure water, and recover isopropanol and unreacted monomers under reduced pressure while heating to 60°C to obtain an acrylic resin dispersed in pure water (b -3).

・Molamine resin (b-4) "Nikalac" (registered trademark) MW-035 (solid content concentration: 70% by mass, solvent: water) manufactured by Sanwa Chemical Co., Ltd. was used. ・Acrylic polyol resin with long chain alkyl group (b-5) In the same manner as described in the aforementioned acrylic resin (b-3), 20 mol% of stearyl (meth)acrylate, 40 mol% of hydroxyethyl (meth)acrylate and 40 mol% The ratio of methyl (meth)acrylate was mixed, diluted with toluene to a solid content concentration of 40% by mass, and 0.5 mol% of azobisisobutyronitrile was added and copolymerized under a nitrogen stream to obtain a resin solution A . ・Hexamethoxymethylolmelamine (b-6) [Preparation of Coating Compositions A~C] The release agent (A), resin or compound (B) obtained as described above were mixed at the solid content mass ratio described in Table 2 to form coating compositions A to C.

[Table 2] Masterbatch Resin Composition Ratio (mass ratio of solid components) Release agent (A) Resin or compound (B) Release agent (A) Resin or compound (B) Coating composition A - (b-1) - 100 Coating composition B - (b-2) - 100 Coating composition C (a-1) (b-3), (b-4) 35 15, 50 Coating composition D (a-2) (b-5), (b-6) 25 70,5

(Example 1) PET-1, PET-2, MB-B, and MB-C were dried under reduced pressure at 180° C. for 2 hours and 30 minutes, and the blending amounts became P1 layer, P2 layer, and Blended in the amount of P3 layers, supplied to 3 separate extruders, melt-extruded, filtered with a filter, and laminated into 3 layers (P1 layer/P3 layer) with a feed block /P2 layer configuration) to make it merge, pass through a T-shaped mold on a cooling casting roll maintained at 42°C, use electrostatic application casting method to wind up, cool and solidify to obtain an unstretched film. Guide the unstretched film between the opposite electrode and the ground roller, introduce nitrogen gas into the device, and perform atmospheric pressure glow discharge on the surface of the P1 layer under the condition that the treatment intensity (E value) becomes 250W·min/ ^m2 caused by plasma treatment.

The treated unstretched film was passed through a static elimination roll whose roll temperature was set at 30° C., and then a sequential biaxial stretching machine was carried out under the conditions described in Table 4. First, it is guided along the length direction to the stretching roller group heated to 60°C to 100°C, stretched to 3.8 times through a three-stage stretching operation, guided to the tenter, and stretched at a stretching temperature of 90°C to 140°C. Stretch in the width direction by 4.4 times, apply heat treatment at 235°C under fixed length, and apply 3% relaxation treatment in the width direction to obtain a biaxially oriented polyester film with a thickness of 35 μm.

[table 3] Composition of Biaxially Aligned Polyester Film P1 layer P3 layer (middle layer) P2 layer (back layer) Constituent resin Resin content (mass%) Add Particle ① Type Particle addition amount (mass%) Constituent resin① Resin content (mass%) Constituent resin① Resin content (mass%) Constituent resin Add Particle② Type Particle addition amount (mass%) Add Particle③ Type Particle addition amount (mass%) Example 1 PET-1 100 - - PET-1 60 PET-2 40 PET-1 Silica-2 0.2 Silica-3 0.05 Example 2 PET-1 99.9 Silica-1 0.1 PET-1 60 PET-2 40 PET-1 Silica-2 0.2 Silica-3 0.05 Example 3 PET-1 100 - - PET-1 60 PET-2 40 PET-1 Silica-2 0.5 Silica-4 0.2 Example 4 PET-1 100 - - PET-1 60 PET-2 40 PET-1 Silica-2 0.1 Silica-3 0.05 Example 5 PET-1 99.9 Silica-1 0.1 PET-1 60 PET-2 40 PET-1 Silica-2 0.2 Silica-3 0.05 Example 6 PET-1 99.9 Silica-1 0.1 PET-1 60 PET-2 40 PET-1 Silica-2 0.2 Silica-3 0.05 Example 7 PET-1 100 - - PET-1 60 PET-2 40 PET-1 Silica-2 0.2 Silica-3 0.05 Example 8 PET-1 100 - - PET-1 60 PET-2 40 PET-1 Silica-2 0.2 Silica-3 0.05 Example 9 PET-1 100 - - PET-1 60 PET-2 40 PET-1 Silica-2 0.2 Silica-3 0.05 Example 10 PET-1 100 - - PET-1 60 PET-2 40 PET-1 Silica-2 0.2 Silica-3 0.05 Example 11 PET-1 100 - - PET-1 60 PET-2 40 PET-1 Silica-2 0.2 Silica-3 0.05 Example 12 PET-1 100 - - PET-1 60 PET-2 40 PET-1 Silica-2 0.2 Silica-3 0.05 Example 12 PET-1 100 - - PET-1 60 PET-2 40 PET-1 Silica-2 0.2 Silica-3 0.05 Example 13 PET-1 99.9 Silica-1 0.1 - - - - PET-1 Silica-2 0.2 Silica-3 0.05 Example 14 PET-1 99.85 Alumina-1 0.15 PET-1 60 PET-2 40 PET-1 Silica-2 0.2 Silica-3 0.05 Example 15 PET-1 99.85 Alumina-1 0.15 PET-1 60 PET-3 40 PET-1 Silica-2 0.2 Silica-3 0.05 Example 16 PET-1 99.85 Alumina-1 0.15 PET-1 60 PET-3 40 PET-1 Silica-2 0.2 Silica-3 0.05 Example 17 PET-1 100 - - PET-1 60 PET-2 40 PET-1 Silica-2 0.05 Silica-3 0.015 Example 18 PET-1 100 - - PET-1 60 PET-2 40 PET-1 Silica-2 0.2 Silica-3 0.05 Comparative example 1 PET-1 99.9 Silica-5 0.1 PET-1 60 PET-2 40 PET-1 Silica-2 0.2 Silica-3 0.05 Comparative example 2 PET-1 100 - - PET-1 60 PET-2 40 PET-1 Silica-2 0.5 Silica-6 0.1 Comparative example 3 PET-1 100 - - PET-1 60 PET-2 40 PET-1 Silica-2 0.2 - - Comparative example 4 PET-1 99.85 Alumina-1 0.7 PET-1 60 PET-2 40 PET-1 Silica-2 0.2 Silica-3 0.05

[Table 4] surface treatment Membrane conditions method condition Processing surface biaxial extension Extended lengthwise Width direction extension Laminated composition Film thickness (μm) Treatment intensity E value gas type Extension ratio (times) Extension ratio (times) Heat treatment temperature (℃) Relaxation treatment (%) Full layer T (μm) P1 layer T _P1 (μm) P3 layer (μm) P2 layer T _P2 (μm) Example 1 plasma treatment 250 Nitrogen P1 layer surface successively 3.8 4.4 235 3 3 floors (P1 floor/P3 floor/P2 floor) 35 3.5 30 1.5 Example 2 plasma treatment 250 Nitrogen P1 layer surface successively 3.8 4.4 235 3 3 floors (P1 floor/P3 floor/P2 floor) 35 3.5 30 1.5 Example 3 plasma treatment 250 Nitrogen P1 layer surface successively 3.8 4.4 235 3 3 floors (P1 floor/P3 floor/P2 floor) 35 3.5 30.5 1.0 Example 4 plasma treatment 250 Nitrogen P1 layer surface successively 3.8 4.4 235 3 3 floors (P1 floor/P3 floor/P2 floor) 35 3.5 28.5 3.0 Example 5 plasma treatment 250 Nitrogen P1 layer surface successively 3.8 4.4 235 3 3 floors (P1 floor/P3 floor/P2 floor) 35 2.0 31.5 1.5 Example 6 plasma treatment 250 Nitrogen P1 layer surface successively 3.8 4.4 235 3 3 floors (P1 floor/P3 floor/P2 floor) 35 1.2 32.3 1.5 Example 7 plasma treatment 150 Nitrogen P1 layer surface successively 3.8 4.4 235 3 3 floors (P1 floor/P3 floor/P2 floor) 35 3.5 30 1.5 Example 8 plasma treatment 100 Nitrogen P1 layer surface successively 3.8 4.4 235 3 3 floors (P1 floor/P3 floor/P2 floor) 35 3.5 30 1.5 Example 9 plasma treatment 50 Nitrogen P1 layer surface successively 3.8 4.4 235 3 3 floors (P1 floor/P3 floor/P2 floor) 35 3.5 30 1.5 Example 10 plasma treatment 250 Nitrogen P1 layer surface successively 3.8 4.4 235 3 3 floors (P1 floor/P3 floor/P2 floor) 35 3.5 30 1.5 Example 11 plasma treatment 250 Nitrogen P1 layer surface successively 3.8 4.4 235 3 3 floors (P1 floor/P3 floor/P2 floor) 35 3.5 30 1.5 Example 12 plasma treatment 250 Nitrogen P1 layer surface successively 3.8 4.4 235 3 3 floors (P1 floor/P3 floor/P2 floor) 35 3.5 30 1.5 Example 13 plasma treatment 250 Nitrogen P1 layer surface successively 3.8 4.4 235 3 2 floors (P1 floor/P2 floor) 35 33.5 - 1.5 Example 14 plasma treatment 250 Nitrogen P1 layer surface successively 3.8 4.4 235 3 3 floors (P1 floor/P3 floor/P2 floor) 35 3.5 30 1.5 Example 15 plasma treatment 250 Nitrogen P1 layer surface successively 3.8 4.4 235 3 3 floors (P1 floor/P3 floor/P2 floor) 35 3.5 30 1.5 Example 16 plasma treatment 250 Nitrogen P1 layer surface successively 3.8 4.4 235 3 3 floors (P1 floor/P3 floor/P2 floor) 35 6.0 27.5 1.5 Example 17 plasma treatment 250 Nitrogen P1 layer surface successively 3.8 4.4 235 3 3 floors (P1 floor/P3 floor/P2 floor) 35 3.5 30 1.5 Example 18 plasma treatment 250 Nitrogen P1 layer surface successively 3.8 4.4 235 3 3 floors (P1 floor/P3 floor/P2 floor) 35 3.5 30 1.5 Comparative example 1 plasma treatment 250 Nitrogen P1 layer surface successively 3.8 4.4 235 3 3 floors (P1 floor/P3 floor/P2 floor) 35 2.0 31.5 1.5 Comparative example 2 plasma treatment 250 Nitrogen P1 layer surface successively 3.8 4.4 235 3 3 floors (P1 floor/P3 floor/P2 floor) 35 3.5 30.5 1.0 Comparative example 3 plasma treatment 250 Nitrogen P1 layer surface successively 3.8 4.4 235 3 3 floors (P1 floor/P3 floor/P2 floor) 35 3.5 28.5 3.0 Comparative example 4 plasma treatment 250 Nitrogen P1 layer surface successively 3.8 4.4 235 3 3 floors (P1 floor/P3 floor/P2 floor) 35 3.5 27.5 1.5

The composition of the obtained biaxially oriented polyester film, analysis of particles contained in the film, surface properties, and film properties are shown in Tables 5 and 6. In addition, the surface characteristics of the surface of the P1 layer mainly composed of polyester resin are as follows. The upper 5% value of the maximum protrusion height: 75nm The number of protrusions with a height of 80nm or more: 0.1/mm ² The number of protrusions with a height of 10nm or more: 500/mm ²

[table 5] Thin film properties Film Contains Particle Analysis IV (dl/g) Amount of COOH (equivalent/t) Tmeta (°C) P1 layer P2 layer P3 layer (middle layer) Average particle size (nm) Maximum particle size D _P1 (nm) T _P1 /D _P1 (-) Average particle size (nm) Degree distribution peak position Maximum particle size D _P2 (nm) T _P2 /D _P2 (-) Degree distribution peak position The area above 30nm and below 400nm The area above 400nm and below 1200nm The area above 30nm and below 400nm The area above 400nm and below 1200nm Example 1 0.58 41 230°C - - - 390 360 500 600 2.5 360 500 Example 2 0.58 41 230°C 75 80 44 390 360 500 600 2.5 360 500 Example 3 0.58 41 230°C - - - 515 360 900 1000 1.0 360 500 Example 4 0.58 41 230°C - - - 410 360 500 600 5.0 360 500 Example 5 0.58 41 230°C 75 80 25 390 360 500 600 2.5 360 500 Example 6 0.58 41 230°C 75 80 15 390 360 500 600 2.5 360 500 Example 7 0.58 41 230°C - - - 390 360 500 600 2.5 360 500 Example 8 0.58 41 230°C - - - 390 360 500 600 2.5 360 500 Example 9 0.58 41 230°C - - - 390 360 500 600 2.5 360 500 Example 10 0.58 41 230°C - - - 390 360 500 600 2.5 360 500 Example 11 0.58 41 230°C - - - 390 360 500 600 2.5 360 500 Example 12 0.58 41 230°C - - - 390 360 500 600 2.5 360 500 Example 13 0.60 38 230°C 75 80 430 390 360 500 600 2.5 360 500 Example 14 0.58 41 230°C 45 60 58 390 360 500 600 2.5 360 500 Example 15 0.57 41 230°C 45 60 58 390 360 500 600 2.5 360 1100 Example 16 0.57 41 230°C 45 60 100 390 360 500 600 2.5 360 1100 Example 17 0.58 41 230°C - - - 395 360 500 600 2.5 360 500 Example 18 0.58 41 230°C - - - 390 360 500 600 2.5 360 500 Comparative example 1 0.58 41 230°C 130 150 13 390 360 500 600 2.5 360 500 Comparative example 2 0.58 41 230°C - - - 480 360 1100 1200 0.8 360 500 Comparative example 3 0.58 41 230°C - - - 360 360 - 400 7.5 360 500 Comparative example 4 0.58 41 230°C 55 140 25 390 360 500 600 2.5 360 500

[Table 6] Properties of Biaxially Aligned Polyester Film P2 layer surface (B side) surface characteristics Static friction coefficient μs (-) The upper 5% value of the maximum protrusion height Sp5%B(nm) Example 1 230 0.6 Example 2 230 0.5 Example 3 1000 0.4 Example 4 200 0.8 Example 5 230 0.5 Example 6 230 0.5 Example 7 230 0.6 Example 8 230 0.5 Example 9 230 0.5 Example 10 230 0.6 Example 11 230 0.6 Example 12 230 0.6 Example 13 230 0.4 Example 14 230 0.6 Example 15 230 0.5 Example 16 230 0.4 Example 17 180 0.7 Example 18 230 0.6 Comparative example 1 230 0.6 Comparative example 2 1200 0.3 Comparative example 3 100 1.0 Comparative example 4 230 0.4

Then, on the surface of the P1 layer of the obtained biaxially oriented polyester film, in a manner as described in Table 7, the coating composition A was coated by the gravure coating method, and dried at a drying temperature of 100° C. for 30 seconds. A coating layer (R1) having a final thickness of 0.1 μm was formed to obtain a biaxially aligned polyester film. The biaxially oriented polyester film is composed of 4 layers of R1 layer/P1 layer/P3 layer/P2 layer. In addition, the thickness unevenness of the obtained biaxially oriented polyester film with the coating layer is as described in Table 7. The evaluation system of production adaptability and use adaptability is shown in Table 8, which is the step transferability (surface damage defect, surface chipping), winding performance (winding wrinkles, winding deviation), and coating of green sheet. A film with good peelability (coatability (cracks), peelability, flake breakage, and surface defects).

[Table 7] Biaxially oriented polyester film with coating layer constitute Coated layer surface (side A) surface characteristics uneven thickness Coating composition Coated surface Coating layer thickness T _R1 (μm) The upper 5% value of the maximum protrusion height Sp5%A(nm) Number of protrusions with a height of 80nm or more N _80nm A (unit/mm ² ) Water contact angle CaR(°) T _MAX -T _MIN (μm) _TAVE (μm) ΔT (%) Example 1 Coating composition A P1 layer surface 0.10 75 0.1 115 1.0 35.1 2.8 Example 2 Coating composition A P1 layer surface 0.10 110 0.2 115 1.0 35.1 2.8 Example 3 Coating composition A P1 layer surface 0.10 75 0.1 115 1.0 35.1 2.8 Example 4 Coating composition A P1 layer surface 0.10 75 0.1 115 1.0 35.1 2.8 Example 5 Coating composition A P1 layer surface 0.10 90 0.4 115 1.0 35.1 2.8 Example 6 Coating composition A P1 layer surface 0.10 100 0.5 115 1.0 35.1 2.8 Example 7 Coating composition A P1 layer surface 0.10 75 0.1 115 1.0 35.1 2.8 Example 8 Coating composition A P1 layer surface 0.10 100 0.2 115 1.5 35.1 4.3 Example 9 Coating composition A P1 layer surface 0.10 110 0.2 115 1.8 35.1 5.1 Example 10 Coating composition B P1 layer surface 0.10 75 0.1 120 1.0 35.1 2.8 Example 11 Coating composition C P1 layer surface 0.10 75 0.1 100 1.0 35.1 2.8 Example 12 Coating composition A P1 layer surface 0.01 75 0.1 115 1.0 35.0 2.9 Example 13 Coating composition A P1 layer surface 0.10 110 0.4 115 1.0 35.1 2.8 Example 14 Coating composition A P1 layer surface 0.10 85 0.3 115 1.0 35.1 2.8 Example 15 Coating composition A P1 layer surface 0.10 100 0.4 115 1.0 35.1 2.8 Example 16 Coating composition A P1 layer surface 0.10 85 0.3 115 1.0 35.1 2.8 Example 17 Coating composition A P1 layer surface 0.10 75 0.1 115 1.0 35.1 2.8 Example 18 Coating composition D P1 layer surface 0.05 75 0.1 105 1.0 35.1 2.8 Comparative example 1 Coating composition A P1 layer surface 0.10 130 0.5 115 1.0 35.1 2.8 Comparative example 2 Coating composition A P1 layer surface 0.10 75 0.1 115 1.0 35.1 2.8 Comparative example 3 Coating composition A P1 layer surface 0.10 75 0.1 115 1.0 35.1 2.8 Comparative example 4 Coating composition A P1 layer surface 0.10 115 0.6 115 1.0 35.1 2.8

[Table 8] production adaptation Purpose Adaptation Step portability Coilability Coating and peeling properties with green sheet Surface Damage Disadvantages surface cutting winding wrinkles winding offset Coatability (cracks) Stripping flake rupture Surface defects Example 1 A A A A A A A A Example 2 A B A A A A B C Example 3 A A A B A A A C Example 4 A A C A A A A A Example 5 A B A A A A B A Example 6 A B A A A A C B Example 7 C A A A A A A A Example 8 B A A B A A A B Example 9 B A A C A A A C Example 10 A A A A C A A A Example 11 A A A A A C A A Example 12 A A A A A C A A Example 13 A B A A A A C C Example 14 AAA A A A A A B A Example 15 AAA A A A A A C B Example 16 AAA A A A A A B A Example 17 AAA A C A A A A AAA Example 18 A A A A A B A A Comparative example 1 A D. A A A A D. D. Comparative example 2 A A A D. A A A D. Comparative example 3 D. A D. A A A A A Comparative example 4 AAA A A A A A D. D.

(Examples 2 to 4) Except that in Example 2, the P1 layer contains the particles of the concentration listed in Table 3, and in Examples 3 and 4, the particles contained in the P2 layer are changed as shown in Table 3. In Example 1, a biaxially oriented polyester film with a thickness of 35 μm was obtained in the same manner. The composition of the obtained biaxially oriented polyester film, analysis of particles contained in the film, surface properties, and film properties are shown in Tables 5-7. In addition, the surface characteristics of the surface of the P1 layer mainly composed of polyester resin in Examples 2 to 4 are as follows. (Example 2) The upper 5% value of the maximum protrusion height: 110nm The number of protrusions with a height of 80nm or more: 0.3/ ^mm2 The number of protrusions with a height of 10nm or more: 700/ ^mm2 (Examples 3 and 4) Maximum protrusion The upper 5% value of the height: 75nm The number of protrusions with a height of 80nm or more: 0.1/ ^mm2 The number of protrusions with a height of 10nm or more: 500/ ^mm2 The evaluation system of production adaptability and application adaptability is shown in Table 8. In Example 2, the chip cracking and surface defects of the surface cutting and the green sheet are inferior to that of Example 1, but both are within the practical range. The other properties were good as in Example 1. In Example 3, the winding deviation and the surface defect of the green sheet are worse than that of Example 1, but both are within the practical range. The other properties were good as in Example 1. In Example 4, the winding wrinkle is inferior to that of Example 1, but both are within the practical range. The other properties were good as in Example 1.

(Examples 5 and 6) In Examples 5 and 6, a biaxially oriented polyester film having a thickness of 35 μm was obtained in the same manner as in Example 1 except that the laminate thickness of the P1 layer was changed as described in Table 4. The composition of the obtained biaxially oriented polyester film, analysis of particles contained in the film, surface properties, and film properties are shown in Tables 5-7. In addition, the surface characteristics of the surface of the P1 layer mainly composed of polyester resin in Examples 5 and 6 are as follows. (Example 5) The upper 5% value of the maximum protrusion height: 90nm The number of protrusions with a height of 80nm or more: 0.4/ ^mm2 The number of protrusions with a height of 10nm or more: 600/ ^mm2 (Example 6) Between the maximum protrusion height The upper 5% value: 95nm The number of protrusions with a height of 80nm or more: ^0.5 /mm The number of protrusions with a height ^of 10nm or more: 650/mm The surface cutting and chip cracking of 5 are worse than that of Example 1, and the chip cracking of Example 6 is further worsened, and the surface defects are also worse than that of Example 1, but they are all within the practical range. The other properties were good as in Example 1.

(Examples 7 to 9) In Examples 7 to 9, except that the treatment intensity of the plasma treatment caused by atmospheric pressure glow discharge was changed to that described in Table 4, a biaxial tube with a thickness of 35 μm was obtained in the same manner as in Example 1. Aligned polyester film. The composition of the obtained biaxially oriented polyester film, analysis of particles contained in the film, surface properties, and film properties are shown in Tables 5-7. In addition, the surface characteristics of the surface of the P1 layer mainly composed of polyester resin in Examples 7 to 9 are as follows. (Example 7) Value of the upper 5% of the maximum protrusion height: 75 nm Number of protrusions with a height of 80 nm or more: 0.06/mm ² Number of protrusions with a height of 10 nm or more: 400/mm ² (Example 8) Between the maximum protrusion height Upper 5% value: 75nm, number of protrusions with a height of 80nm or more: 0.1/ ^mm2 , number of protrusions with a height of 10nm or more: 330/ ^mm2 (Example 9) Upper 5% value of the maximum protrusion height: 75nm, with a height of 80nm or more The number of protrusions: 0.1/ ^mm The number of protrusions with a height of 10nm or more: 300/ ^mm The evaluation system of production adaptability and application adaptability is as shown in Table 8, and the surface damage defect of embodiment 7 is inferior to that of implementation Example 1, Example 8, and Example 9 are inferior to Example 1 in addition to the defects of surface damage, winding deviation and surface defects of the green sheet, but they are all within the practical range. The other properties were good as in Example 1.

(Examples 10-12) Except that in Examples 10 and 11, the coating composition coated on the biaxially aligned polyester film was changed as described in Table 7, the thickness of the coating layer was changed in Example 12 Except as described in Table 7, a biaxially oriented polyester film having a thickness of 35 μm was obtained in the same manner as in Example 1. The composition of the obtained biaxially oriented polyester film, analysis of particles contained in the film, surface properties, and film properties are shown in Tables 5-7. In addition, the surface characteristics of the surface of the P1 layer mainly composed of polyester resin in Examples 10 to 12 are as follows. (Examples 10-12) Upper 5% value of the maximum protrusion height: 75nm Number of protrusions with a height of 80nm or more: 0.1/ ^mm2 Number of protrusions with a height of 10nm or more: 500/ ^mm2 Production suitability and application suitability The evaluation system is as shown in Table 8. The coating property of the green sheet in Example 10 is better than that of Example 1, and the peeling properties of the green sheet in Examples 11 and 12 are respectively better than that of Example 1. The other properties were good as in Example 1.

(Example 13) In Example 13, except that the structure of the biaxially oriented polyester film was changed to a two-layer structure as described in Table 3 and Table 4, a biaxially oriented polyester film with a thickness of 35 μm was obtained in the same manner as in Example 1. Aligned polyester film. The composition of the obtained biaxially oriented polyester film, analysis of particles contained in the film, surface properties, and film properties are shown in Tables 5-7. In addition, the surface characteristics of the surface of the P1 layer mainly composed of polyester resin in Example 13 are as follows. The upper 5% value of the maximum protrusion height: 110nm The number of protrusions with a height of 80nm or more: 0.4/ ^mm2 The number of protrusions with a height of 10nm or more: 600/ ^mm2 The evaluation system of production adaptability and application adaptability is shown in Table 8 It shows that the surface cutting of embodiment 13, the chip cracking and surface defects of the green sheet are inferior to embodiment 1, but they are all within the practical range. The other properties were good as in Example 1.

(Example 14) A biaxially oriented polyester film having a thickness of 35 μm was obtained in the same manner as in Example 1 except that the configuration of the biaxially oriented polyester film was changed to that described in Table 3 and Table 4 in Example 14. The composition of the biaxially oriented polyester film obtained, analysis of particles contained in the film, surface properties, and film properties are shown in Tables 5-7. In addition, the surface characteristics of the surface of the P1 layer mainly composed of polyester resin in Example 14 are as follows. The upper 5% value of the maximum protrusion height: 85nm The number of protrusions with a height of 80nm or more: 0.3/ ^mm2 The number of protrusions with a height of 10nm or more: 550/ ^mm2 The evaluation system of production adaptability and application adaptability is shown in Table 8 Show, the surface cutting of embodiment 14, the flake cracking of green sheet are inferior to embodiment 1, but all are in the scope of practicality. The other characteristics were good films as in Example 1.

(Example 15, 16) Except that in Examples 15 and 16, the composition of the biaxially oriented polyester film is to use PET-3 recycled raw materials in the P3 layer of the middle layer, and change it to be as described in Table 3 and Table 4, the same as in Example 1 Similarly, a biaxially oriented polyester film having a thickness of 35 µm and consisting of three laminated layers was obtained. The composition of the obtained biaxially oriented polyester film, analysis of particles contained in the film, surface properties, and film properties are shown in Tables 5-7. In addition, the surface characteristics of the surface of the P1 layer mainly composed of polyester resin in Example 15 and Example 16 are as follows.

(Example 15) The upper 5% value of the maximum protrusion height: 100 nm The number of protrusions with a height of 80 nm or more: 0.4/mm ^The number of protrusions with a height of 10 nm or ^more : 700/mm (Example 16) The maximum protrusion height The upper 5% value: 85nm The number of protrusions with a height of 80nm or more: ^0.3 /mm The number of protrusions with ^a height of 10nm or more: 600/mm 15 Since the middle layer contains particles with a particle diameter of more than 800nm showing a very large peak in the analysis of the volume-based particle size distribution, the cracking and surface defects of the flakes are inferior to those of Example 1, and the thickness of the P1 layer of Example 16 is compared to that of the implementation. Example 15 is thicker, and the surface defects are improved, but on the other hand, the cracking of the flakes is inferior to that of Example 1, but they are all within the practical range. The other properties were good as in Example 1.

(Example 17) In Example 17, a biaxially oriented polyester film having a thickness of 35 μm was obtained in the same manner as in Example 1, except that the configuration of the biaxially oriented polyester film was changed to that described in Table 3 and Table 4. The composition of the biaxially oriented polyester film obtained, analysis of particles contained in the film, surface properties, and film properties are shown in Tables 5-7. In addition, the surface characteristics of the surface of the P1 layer mainly composed of polyester resin in Example 17 are as follows. The upper 5% value of the maximum protrusion height: 75nm The number of protrusions with a height of 80nm or more: 0.1/ ^mm2 The number of protrusions with a height of 10nm or more: 500/ ^mm2 The evaluation system of production adaptability and application adaptability is shown in Table 8 Show, the winding wrinkle system of embodiment 17 is inferior to embodiment 1, but is in the practical range. The other characteristics were good films as in Example 1.

(Example 18) In Example 18, except that the composition of the biaxially oriented polyester film was changed as described in Table 7, and the coating composition constituting the coating layer and the thickness of the coating layer were changed, the same procedure as in Example 1 was carried out. A biaxially aligned polyester film with a thickness of 35 μm was obtained. The composition of the obtained biaxially oriented polyester film, analysis of particles contained in the film, surface properties, and film properties are shown in Tables 5-7. In addition, the surface characteristics of the surface of the P1 layer mainly composed of polyester resin in Example 18 are as follows. The upper 5% value of the maximum protrusion height: 75nm The number of protrusions with a height of 80nm or more: 0.1/ ^mm2 The number of protrusions with a height of 10nm or more: 500/ ^mm2 The evaluation system of production adaptability and application adaptability is shown in Table 8 It shows that the surface cutting of Example 18 and the release property of the green sheet are inferior to that of Example 1, but both are within the practical range. The other properties were good as in Example 1.

(Comparative Example 1) In Comparative Example 1, except that the particles contained in the P1 layer were changed as described in Table 3, a biaxially aligned polyester film with a thickness of 35 μm was obtained in the same manner as in Example 1. The composition of the obtained biaxially oriented polyester film, analysis of particles contained in the film, surface properties, and film properties are shown in Tables 5-7. In addition, the surface characteristics of the surface of the P1 layer mainly composed of polyester resin in Comparative Example 1 are as follows. The upper 5% value of the maximum protrusion height: 130nm The number of protrusions with a height of 80nm or more: 0.5/ ^mm2 The number of protrusions with a height of 10nm or more: 600/ ^mm2 The evaluation system of production adaptability and application adaptability is shown in Table 8 Show, comparative example 1 is the film of embodiment 1 that the sheet crack and surface defect of green sheet are significantly inferior.

(Comparative Examples 2 and 3) In Comparative Examples 2 and 3, except that the particles contained in the P2 layer were changed as described in Table 3, a biaxially oriented polyester film with a thickness of 35 μm was obtained in the same manner as in Example 1. The composition of the obtained biaxially oriented polyester film, analysis of particles contained in the film, surface properties, and film properties are shown in Tables 5-7. In addition, the surface characteristics of the surface of the P1 layer mainly composed of polyester resin in Comparative Examples 2 and 3 are as follows. The upper 5% value of the maximum protrusion height: 75nm The number of protrusions with a height of 80nm or more: 0.1/ ^mm2 The number of protrusions with a height of 10nm or more: 500/ ^mm2 The evaluation system of production adaptability and application adaptability is shown in Table 8 It shows that in Comparative Example 2, the winding deviation system is significantly worse than that of the film of Example 1, and in Comparative Example 3, the defects of surface damage and winding wrinkles are significantly worse than the film of Example 1.

(Comparative Example 4) In Comparative Example 4, a biaxially aligned polyester film having a thickness of 35 μm was obtained in the same manner as in Example 1, except that the particles contained in the P1 layer were changed as described in Table 3. The composition of the obtained biaxially oriented polyester film, analysis of particles contained in the film, surface properties, and film properties are shown in Tables 5-7. In addition, the surface characteristics of the surface of the P1 layer mainly composed of polyester resin in Comparative Example 4 are as follows. The upper 5% value of the maximum protrusion height: 115nm The number of protrusions with a height of 80nm or more: 0.6/ ^mm2 The number of protrusions with a height of 10nm or more: 850/ ^mm2 The evaluation system of production suitability and application suitability is shown in Table 8 , Comparative Example 4 is a thin film of the green sheet whose cracking and surface defects are significantly inferior to those of the film of Example 1. [Possibility of industrial use]

Since the biaxially oriented polyester film of the present invention has a release coating surface with excellent smoothness and a back surface with excellent smoothness, there is little transfer of irregularities on the surface of the green sheet even after being wound up in a roll, and the coating and peeling properties are improved. It is excellent in properties and does not lose its smoothness even when recycled materials are used for the intermediate layer, so it can be applied as a process film for green sheet release with less environmental load.

1: Layer with A surface (P1 layer or R1 layer) 2: Surface with protrusions (A surface) 3: Zero surface in scanning white interference microscope measurement (average surface; height 0 nm) 4: Line with height 10 nm (R _10nm ) 5: Line with a height of 80nm (R _80nm ) 6: Protrusions present on the A surface 7: Among the values of the maximum protrusion height in each field of view of the A surface, there is a value of the maximum protrusion height corresponding to the value of the upper 5% Protrusion 8: The value of the maximum protrusion height corresponding to the upper 5% of the values of the maximum protrusion height in each field of view on the A surface (Sp5%A) 9: The protrusion 10 with the maximum height existing on the A surface : Layer with B surface (P2 layer) 11: The opposite surface (B surface) of the aforementioned A surface with protrusions 12: The protrusions present on B surface 13: Among the values of the maximum protrusion height in each field of view of B surface, The value of the maximum protrusion height corresponding to the upper 5% of the value of the maximum protrusion height corresponding to the upper 5% of the value of the protrusion 14: B surface in each field of view (Sp5%B ) 15: Protrusion with maximum height present on B side 16: Polyester resin layer (P1 layer) with A side 17: Intermediate layer (P3 layer) 18: Layer with B side (P2 layer) 19: Biaxial Oriented polyester film 20: Coating layer (R1 layer) with A surface 21: Biaxially oriented polyester film with coating layer

Fig. 1 is a conceptual diagram showing Sp5%A measured with a scanning white-color interference microscope. Fig. 2 is a conceptual diagram showing Sp5%B measured with a scanning white interference microscope. Fig. 3 is a three-layer structure diagram of the biaxially oriented polyester film of the present invention. Fig. 4 is a diagram showing the four-layer structure of a biaxially oriented polyester film having the coating layer of the present invention.

1: Layer with A side (P1 layer or R1 layer)

2: Surface with protrusions (A surface)

3: Zero surface (average surface; height 0nm) in scanning white interference microscope measurement

4: Height 10nm line (R _10nm )

5: Height 80nm line (R _80nm )

6:Protrusion existing on A side

7: Among the values of the maximum protrusion height in each field of view of the A surface, the protrusion having a value of the maximum protrusion height corresponding to the upper 5% of the value

8: The value of the maximum protrusion height corresponding to the upper 5% of the values of the maximum protrusion height in each field of view on the A side (Sp5%A)

9: The protrusion with the maximum height exists on the A surface

Claims (16)

A biaxially oriented polyester film, which has a surface (side A) satisfying the following (1), and a surface (side B) opposite to the A side satisfying the following (2); (1) The above-mentioned surface A has protrusions. Among the values of the maximum protrusion height in each field of view obtained by the following method, the value of the maximum protrusion height corresponding to the upper 5% of the value is Sp5%A (nm) , Sp5%A is below 110; (2) The surface B has protrusions, and among the values of the maximum protrusion height in each field of view obtained by the following method, the value of the maximum protrusion height corresponding to the upper 5% value is Sp5%B (nm) , Sp5%B is between 150 and 1000; (Measurement method of maximum protrusion height) Using a scanning white interference microscope (VertScan) with a 10 objective lens, measure the surface image of 561 μm□ field of view in 100 fields of view, obtain the maximum protrusion height Sp value in each field of view, and set the value corresponding to the upper 5% of them as Sp5% value. The biaxially oriented polyester film according to claim 1, wherein protrusions exist on the surface of the A surface, and when the number of protrusions with a height of 80 nm or more is N _80nm A (unit/mm ² ), N _80nm A is 0.4 or less. The biaxially oriented polyester film as claimed in claim 1 or 2, wherein protrusions exist on the surface of the aforementioned A surface, and when the number of protrusions with a height of 10 nm or more is set as N _10nm A (unit/mm ² ), N _10nm A is 300 Above 1000 below. The biaxially oriented polyester film according to any one of claims 1 to 3, wherein the polyester resin layer (layer P1) has the aforementioned A-side. The biaxially oriented polyester film according to any one of claims 1 to 4, wherein when the thickness of the P1 layer is T _P1 (μm), T _P1 is not less than 2 and not more than 10. The biaxially oriented polyester film according to any one of Claims 1 to 5, wherein the aforementioned P1 layer contains particles, and when the maximum particle diameter of the particles contained in the P1 layer is set as D _P1 (μm), T _P1 /D _P1 20 to 100. The biaxially oriented polyester film according to claim 1, wherein CaR is 100 to 120 when the water contact angle of the surface A is CaR (°). The biaxially oriented polyester film according to claim 7, wherein the coating layer (R1 layer) has the aforementioned A surface, and the coating layer (R1 layer) is provided on the layer (P1 layer) mainly composed of the aforementioned polyester resin . The biaxially oriented polyester film according to claim 7 or 8, wherein the aforementioned R1 layer contains at least any one of polysiloxane resin, long-chain alkyl resin or acrylic resin as a main component. The biaxially oriented polyester film according to any one of claims 7 to 9, wherein when the thickness of the P1 layer is T _R1 (μm), T _R1 is not less than 0.01 and not more than 1.00. The biaxially oriented polyester film according to any one of Claims 1 to 10, wherein when the layer having the aforementioned B surface is set as the P2 layer, it has a P3 layer containing particles between the aforementioned P1 layer and the aforementioned P2 layer Composition of at least 3 layers. The biaxially oriented polyester film according to any one of claims 1 to 11, wherein the P2 layer contains at least two kinds of particles with different average particle diameters. As the biaxially oriented polyester film according to any one of claims 1 to 12, wherein the thickness of the aforementioned P2 layer is set as T _P2 (μm), and the maximum particle diameter of the particles contained in the P2 layer is set as D _P2 (μm) ), T _P2 /D _P2 is not less than 1 and not more than 5. The biaxially oriented polyester film according to any one of claims 1 to 13, wherein the film thickness is measured in the film width direction (the same direction as the film roll width direction), and the average thickness of the film is set as T _AVE (μm ), when the maximum value of the film thickness is set as T _MAX (μm), and the minimum value is set as T _MIN (μm), the thickness unevenness ΔT (%) represented by the following formula (1) is 5.0 or less; ΔT (%) =100×(T _MAX -T _MIN )/T _AVE・・・Formula (1). The biaxially oriented polyester film according to any one of claims 1 to 14, wherein the coefficient of static friction between the surface A and the surface B is 0.8 or less. The biaxially oriented polyester film according to any one of claims 1 to 15, which is used as a support film for forming a green sheet in the step of manufacturing a laminated ceramic capacitor.

Images