Polyester film

Abstract

The present invention addresses the problem of providing a polyester film that can be used to manufacture a ceramic green sheet with excellent smoothness. A polyester film according to the present invention comprises an antistatic layer, a polyester base material, and a release layer in this order. The polyester base material substantially does not contain particles. The maximum protrusion height Sp of the surface of the release layer is less than 60 nm. The antistatic layer contains particles, and the surface resistance value of the antistatic layer surface is less than 1x1011Ω / □.

Description

polyester film

[0001] This invention relates to a polyester film.

[0002] Polyester films are used in a wide range of applications from the viewpoint of processability, mechanical properties, electrical properties, dimensional stability, transparency, and chemical resistance. One application of polyester films is as a release film. Specifically, this application involves providing a release layer on the surface of a polyester substrate, manufacturing various components on the surface of the release layer, and then peeling off those components. For example, Patent Document 1 discloses a release film having a release layer, a polyester substrate, and a particle-containing layer in that order.

[0003] International Publication No. 2023 / 281972

[0004] If the surface of a polyester film having a release layer is deformed, it may reduce the smoothness of various components peeled off from that surface. In particular, if the surface of the release layer of a polyester film used in the manufacture of ceramic green sheets is deformed, that shape may be transferred to the ceramic green sheet, causing fluctuations in the thickness of the ceramic green sheet and potentially affecting the performance of the manufactured multilayer ceramic capacitor. The inventors of this invention, with reference to the technology described in Patent Document 1, further investigated polyester films having a release layer and found that there is room for further improvement in the smoothness of the surface of the polyester film.

[0005] In view of the above circumstances, the object of the present invention is to provide a polyester film that can be used to manufacture ceramic green sheets with excellent smoothness.

[0006] The inventors of this invention have diligently studied and, as a result, completed the present invention. Specifically, they have found that the above problems can be solved by the following configuration.

[0007] [1] The material comprises an antistatic layer, a polyester substrate, and a release layer in this order, wherein the polyester substrate is substantially free of particles, the maximum protrusion height Sp on the surface of the release layer is less than 60 nm, the antistatic layer contains particles, and the surface resistance of the surface of the antistatic layer is 1.0 × 10⁻⁶１１ [1] A polyester film having a coefficient of gravity less than Ω / □. [2] The polyester film according to [1], wherein the maximum protrusion height Sp on both surfaces of the polyester film is less than 60 nm. [3] The polyester film according to [1] or [2] for use in manufacturing ceramic green sheets. [4] The polyester film according to any one of [1] to [3], wherein the antistatic layer comprises a mixture of polyethylenedioxythiophene and polystyrene sulfonate. [5] The polyester film according to [4], wherein the antistatic layer comprises at least one selected from the group consisting of a binder having a sulfo group, a binder not having an acid group, and a binder having a carboxylic acid group and having an acid value of 10 mg KOH / g or less. [6] The polyester film according to any one of [1] to [5], wherein the indentation modulus of the antistatic layer measured by an atomic force microscope is 1.5 to 8.0 GPa. [7] The polyester film according to any one of [1] to [6], wherein the antistatic layer comprises at least one selected from the group consisting of polyester, polyurethane, or acrylic resin. [8] A polyester film according to any one of [1] to [7], wherein the antistatic layer contains a surfactant. [9] A polyester film according to any one of [1] to [8], wherein the silicon atom content on the surface of the release layer is 1 to 15 atm%.

[10] A polyester film according to any one of [1] to [9], wherein the release layer contains at least one resin selected from the group consisting of acrylic resin having siloxane bonds and urethane resin having siloxane bonds.

[11] The resin is -Si(R) ３The polyester film according to

[10] , having a structure represented by, where R independently represents an alkyl group or an aryl group.

[12] The polyester film according to any one of [1] to

[11] , wherein the antistatic layer is a layer formed by in-line coating.

[13] The polyester film according to any one of [1] to

[12] , wherein the release layer is a layer formed by in-line coating.

[14] The polyester film according to any one of [1] to

[13] , wherein the antistatic layer and the polyester substrate are in contact, and the polyester substrate and the release layer are in contact.

[0008] According to the present invention, a polyester film can be provided that can be used to manufacture ceramic green sheets with excellent smoothness.

[0009] This is a cross-sectional view showing an example of the structure of the polyester film of the present invention.

[0010] The present invention will now be described in detail. The following descriptions of constituent elements may be based on typical embodiments of the present invention, but the present invention is not limited to such embodiments.

[0011] The following definitions are used to express the meaning of each term used in this specification. In this specification, a numerical range expressed using "~" means a range that includes the numbers before and after "~" as the lower and upper limits. In numerical ranges described stepwise in this specification, the upper or lower limit stated in one numerical range may be replaced with the upper or lower limit of another numerical range described stepwise. Also, in numerical ranges described in this specification, the upper or lower limit stated in one numerical range may be replaced with the values ​​shown in the examples. In this specification, the amount of each component in a composition means the total amount of multiple substances present in the composition if there are multiple substances corresponding to each component in the composition, unless otherwise specified. Also, in this specification, the amount of each component in each layer or component means the total amount of multiple substances present in each layer or component if there are multiple substances corresponding to each component in each layer or component, unless otherwise specified. In this specification, the term "process" includes not only independent processes but also processes that cannot be clearly distinguished from other processes, as long as the intended purpose of the process is achieved. In this specification, a combination of two or more preferred embodiments is a more preferred embodiment.

[0012] In this specification, "longitudinal direction" means the longitudinal direction of the polyester film during the manufacturing of the polyester film, and is synonymous with "conveying direction," "MD," and "machine direction." In this specification, "width direction" and "TD" mean the direction perpendicular to the longitudinal direction. In this specification, "orthogonal" is not limited to strictly orthogonal, but includes approximately orthogonal. "Approximately orthogonal" means that the directions intersect at 90° ± 5°, preferably at 90° ± 3°, and more preferably at 90° ± 1°.

[0013] In this specification, "(meth)acrylic" is a general term for acrylic and methacrylic, and means "one or more of acrylic and methacrylic." Similarly, "(meth)acrylate" means "one or more of acrylate and methacrylate," and "(meth)acrylic acid" means "one or more of acrylic acid and methacrylic acid." "Acrylic resin" means a resin containing constituent units derived from (meth)acrylate. In this specification, unless otherwise specified, refractive index means the refractive index for light with a wavelength of 550 nm, measured using an Abbe refractometer (NAR-2T, manufactured by Atago Co., Ltd.). In this specification, unless otherwise specified, the weight-average molecular weight (Mw) and number-average molecular weight (Mn) are determined by gel permeation chromatography (GPC) analysis using columns of TSKgel GMHxL, TSKgel G4000HxL, TSKgel G2000HxL, and / or TSKgel Super HZM-N (all trade names of Tosoh Corporation), using THF (tetrahydrofuran) as the solvent, detection by differential refractometer, and conversion using polystyrene as the standard substance.

[0014] [Polyester Film] The polyester film of the present invention (hereinafter also referred to as "this film") has an antistatic layer, a polyester substrate, and a release layer in this order, wherein the polyester substrate is substantially free of particles, the maximum protrusion height Sp on the surface of the release layer is less than 60 nm, the antistatic layer contains particles, and the surface resistance value of the surface of the antistatic layer is 1 × 10⁻⁶ １１ It is characterized by being less than Ω / □.

[0015] This film, having the above-described structure, provides a polyester film that enables the production of ceramic green sheets with excellent smoothness. Although the details of this reason are not clear, it is generally presumed to be as follows: Polyester films with a release layer may have foreign matter adhering to their surface during or after the manufacturing process. When polyester films are stored stacked or wound into rolls, the foreign matter adhering to the polyester film deforms the surface of the polyester film. It is presumed that such deformation reduces the smoothness of the ceramic green sheet peeled from the surface of the release layer. In this film, the surface resistance value of the antistatic layer surface is 1 × 10⁻⁶. １１ It is presumed that the increase in charge during the transport and delivery process is suppressed, and the adhesion of foreign matter to the film surface is reduced, due to the fact that the Ω / □ value is less than 1 / 2, the antistatic layer contains particles, the surface on the antistatic layer side has good slipperiness, and the maximum protrusion height Sp on the release layer surface is less than 60 nm. As a result, it is presumed that deformation of the film surface is suppressed, and the smoothness of the ceramic green sheet manufactured using this film is improved.

[0016] The structure of this film will be described in detail below. Figure 1 is a cross-sectional view showing an example of the structure of this film. The polyester film 1 has an antistatic layer 2, a polyester substrate 4, and a release layer 6 in this order. In the polyester film 1, the antistatic layer 2 and the polyester substrate 4 are in contact, and the polyester substrate 4 and the release layer 6 are in contact. That is, the polyester film 1 consists of an antistatic layer 2, a polyester substrate 4, and a release layer 6. The polyester film of the present invention is not limited to the embodiment shown in Figure 1, and may have an intermediate layer between the antistatic layer 2 and the polyester substrate 4, and / or between the polyester substrate 4 and the release layer 6.

[0017] One surface 21 of the polyester film 1 is also the surface of the antistatic layer 2. The other surface 61 of the polyester film 1 is also the surface of the release layer 6. In this specification, the exposed surface on the antistatic layer side of the film (corresponding to surface 21 in the figure) may be described as the "antistatic layer surface" or "smooth surface," and the exposed surface on the release layer side of the film (corresponding to surface 61 in the figure) may be described as the "release layer surface" or "release surface," and both may be collectively referred to as "both surfaces."

[0018] <Polyester Substrate> A polyester substrate is a film-like object containing polyester as its main polymer component. Here, "main polymer component" refers to the polymer that has the highest content (mass) among all polymers contained in the film. A polyester substrate may contain only one type of polyester, or it may contain two or more types of polyester.

[0019] The polyester substrate is substantially particle-free. Whether the polyester substrate is substantially particle-free is confirmed by the following procedure. Ten different locations on the cross-section of the polyester substrate are observed using a scanning electron microscope to check for the presence or absence of particles between 10 nm and 10 μm in size in the cross-section of the polyester substrate. The magnification during observation is adjusted to 5,000 to 20,000 times. If particles are observed at any location, it means that particles are present in the release layer. On the other hand, if no particles are found at any location on the cross-section, it means that the polyester substrate does not contain particles. Here, the particles include the particles (inorganic particles and organic particles) contained in the antistatic layer described later.

[0020] As the polyester substrate, a biaxially oriented polyester substrate is preferred. "Biaxial orientation" means the property of having molecular orientation in two axial directions. Molecular orientation is measured using a microwave transmission type molecular orientation meter (e.g., MOA-6004, manufactured by Oji Instruments Co., Ltd.). The angle between the two axial directions is preferably within the range of 90° ± 5°, more preferably within the range of 90° ± 3°, and even more preferably within the range of 90° ± 1°. Molecular orientation changes by stretching, and a biaxially oriented polyester substrate can be manufactured by biaxial stretching. A preferred embodiment of the polyester substrate is the polyester substrate described in paragraphs

[0021] to

[0039] of the specification of International Publication No. 2022 / 019113, and the above content is incorporated into this specification.

[0021] (Polyester) Polyester is a polymer having ester bonds in its main chain. Polyester is usually formed by polycondensation of a dicarboxylic acid compound and a diol compound, as described later. There are no particular limitations on the polyester, and known polyesters can be used. Examples of polyesters include polyethylene terephthalate (PET), polypropylene terephthalate (PPT), polybutylene terephthalate (PBT), polyethylene-2,6-naphthalate (PEN), and copolymers thereof, with PET, PEN, or copolymers thereof being preferred, and PET being more preferred.

[0022] The intrinsic viscosity (IV) of this film is preferably 0.50 dl / g or more and less than 0.80 dl / g, more preferably 0.55 dl / g or more and less than 0.70 dl / g, and even more preferably 0.60 dl / g or more and less than 0.70 dl / g. The intrinsic viscosity (IV) of this film can be determined from the viscosity of the solution at 25°C after obtaining a solution by dissolving this film in a 1,1,2,2-tetrachloroethane / phenol (= 2 / 3 [mass ratio]) mixed solvent. The melting point (Tm) of the polyester is preferably 220 to 270°C, more preferably 245 to 265°C. The glass transition temperature (Tg) of the polyester is preferably 65 to 90°C, more preferably 70 to 85°C.

[0023] The method for producing polyester is not particularly limited, and known methods can be used. For example, polyester can be produced by polycondensation of at least one dicarboxylic acid compound and at least one diol compound in the presence of a catalyst.

[0024] The catalyst used in the production of catalyst polyester is not particularly limited, and any known catalyst usable for polyester synthesis can be used. Examples of catalysts include alkali metal compounds (e.g., potassium compounds, sodium compounds), alkaline earth metal compounds (e.g., calcium compounds, magnesium compounds), zinc compounds, lead compounds, manganese compounds, cobalt compounds, aluminum compounds, antimony compounds, titanium compounds, aluminum compounds, germanium compounds, and phosphorus compounds. Among these, titanium compounds or aluminum compounds are preferred because they are less likely to generate foreign matter in the polyester substrate. Only one type of catalyst may be used, or two or more types may be used in combination. It is also preferable to use at least one metal catalyst selected from potassium compounds, sodium compounds, calcium compounds, magnesium compounds, zinc compounds, lead compounds, manganese compounds, cobalt compounds, aluminum compounds, antimony compounds, titanium compounds, and germanium compounds in combination with a phosphorus compound. When using multiple catalysts, it is preferable to adopt the types and contents of each compound described in paragraphs

[0055] to

[0062] of Japanese Patent No. 5575671. In this film, when the titanium compound content is 5 to 15 ppm by mass in terms of Ti element, the magnesium compound content is preferably 60 to 90 ppm by mass in terms of Mg element, and the phosphorus compound content is preferably 5 to 35 ppm by mass in terms of P element.

[0025] Furthermore, from the viewpoint of reducing environmental impact and adjusting the maximum protrusion height Sp of the smooth surface to a desired range, the antimony compound content is preferably 0 to 1 ppm by mass in terms of Sb element relative to the total mass of the film. By using a titanium compound or an aluminum compound as a catalyst, it is possible to manufacture a film with the desired surface properties without using an antimony compound.

[0026] As the titanium compound, an organic chelate titanium complex is preferred. An organic chelate titanium complex is a titanium compound having an organic acid as a ligand. Examples of organic acids include citric acid, lactic acid, trimellitic acid, and malic acid. As the titanium compound, the titanium compounds described in paragraphs

[0049] to

[0053] of Japanese Patent No. 5575671 can also be used, and the contents of the above publication are incorporated herein by reference. The titanium compound content is preferably 1 to 300 ppm by mass, more preferably 3 to 20 ppm by mass, and even more preferably 5 to 15 ppm by mass, based on the total mass of the film in terms of Ti element. The content of each element can be measured by inductively coupled plasma mass spectrometry (ICP-MS).

[0027] Examples of aluminum compounds include organoaluminum compounds and their partial hydrolysates. Preferred organoaluminum compounds are carboxylates, inorganic acid salts, or chelate compounds, with aluminum acetate, basic aluminum acetate, aluminum lactate, aluminum chloride, aluminum hydroxide, aluminum chloride hydroxide, or aluminum acetylacetonate being more preferred.

[0028] Dicarboxylic acid compounds Examples of dicarboxylic acid compounds include aliphatic dicarboxylic acid compounds, alicyclic dicarboxylic acid compounds, and aromatic dicarboxylic acid compounds, as well as dicarboxylic acid esters such as methyl ester compounds and ethyl ester compounds of these dicarboxylic acids. Among these, aromatic dicarboxylic acids or aromatic dicarboxylic acid methyl are preferred. Examples of aromatic dicarboxylic acid compounds include terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, and 1,8-naphthalenedicarboxylic acid. Dicarboxylic acid compounds may be used individually or in combination of two or more.

[0029] Diol compounds Examples of diol compounds include aliphatic diol compounds, alicyclic diol compounds, and aromatic diol compounds, with aliphatic diol compounds being preferred. Examples of aliphatic diol compounds include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,2-butanediol, 1,3-butanediol, and neopentyl glycol, with ethylene glycol being preferred. Examples of alicyclic diol compounds include cyclohexanedimethanol, spiroglycol, and isosorbide. Diol compounds may be used individually or in combination of two or more.

[0030] - In the manufacture of end-capping polyester, an end-capping agent may be used as needed. By using an end-capping agent, a structure derived from the end-capping agent is introduced to the end of the polyester. As an end-capping agent, refer to paragraphs

[0055] to

[0064] of Japanese Patent Application Publication No. 2014-189002, which are incorporated herein by reference.

[0031] As a method for synthesizing polyester, the method described in paragraphs

[0033] to

[0070] of Japanese Patent No. 5575671 can also be used, and this content is incorporated herein.

[0032] The polyester content in the polyester substrate is preferably 85% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably 98% by mass or more, based on the total mass of the polyester substrate. The upper limit of the polyester content is not limited and can be appropriately set within a range of 100% by mass or less, based on the total mass of the polymer in the polyester substrate.

[0033] When the polyester base material contains PET, the PET content is preferably 90 to 100% by mass, more preferably 95 to 100% by mass, even more preferably 98 to 100% by mass, and particularly preferably 100% by mass, relative to the total mass of polyester in the polyester base material.

[0034] The polyester substrate may contain components other than polyester (for example, catalysts, unreacted raw material components, particles, and water). The polyester substrate may be manufactured using polyester that has been recycled from film scraps, recovered polyester, etc. For example, when recovering from biaxially oriented polyester film, polyester obtained in the process of manufacturing unoriented polyester film, longitudinally oriented polyester film, and biaxially oriented polyester film can be recovered. Film scraps obtained by slitting polyester film can also be recovered. In this film, it is preferable to remove the release layer and re-pelletize it for material recycling, and it is preferable to mix the polyester chipped from the film with the release layer removed with raw material pellets for material recycling. The polyester substrate may also be a polyester substrate manufactured using chemically recycled recycled polyester.

[0035] The thickness of the polyester substrate is preferably 200 μm or less, more preferably 100 μm or less, more preferably 50 μm or less, even more preferably 40 μm or less, and particularly preferably 35 μm or less. There is no particular lower limit to the thickness, but in terms of improving strength and processability, it is preferably 1 μm or more, more preferably 3 μm or more, even more preferably 10 μm or more, and particularly preferably 20 μm or more. The thickness of the polyester substrate is the arithmetic mean of the thicknesses of five points in the polyester substrate in a section prepared having a cross-section perpendicular to the main surface of the polyester film, measured using a scanning electron microscope (SEM) or transmission electron microscope (TEM).

[0036] <Antistatic Layer> This film has an antistatic layer. The antistatic layer contains particles and is not particularly limited as long as the surface resistance value of this film falls within the above range. The antistatic layer may be provided in contact with the polyester substrate without other layers, or it may be provided via other layers. It is preferable that the antistatic layer is in contact with the polyester substrate. It is also preferable that the antistatic layer is the outermost layer of this film. That is, it is preferable that the surface of the antistatic layer is a smooth surface.

[0037] Examples of antistatic layers include layers containing particles and conductive compounds, with layers containing particles, conductive compounds, and binders being preferred.

[0038] (Particles) Examples of particles included in the antistatic layer include inorganic particles and organic particles. Examples of inorganic particles include silica particles (silicon dioxide particles, colloidal silica), titania particles (titanium oxide particles), calcium carbonate, barium sulfate, and alumina particles (aluminum oxide particles). Examples of organic particles include resin particles. Examples of resins that make up the resin particles include acrylic resins such as polymethyl methacrylate (PMMA), polyester resins, silicone resins, styrene resins, urethane resins, and styrene-acrylic resins. The resin particles may or may not have a crosslinked structure. Specifically, examples include non-crosslinked acrylic resin particles, non-crosslinked styrene resin particles, crosslinked acrylic resin particles, crosslinked urethane resin particles, and divinylbenzene crosslinked particles.

[0039] The average particle diameter of the particles contained in the antistatic layer is not particularly limited, but is preferably 1 to 1000 nm, more preferably 1 to 250 nm, more preferably 10 to 200 nm, and even more preferably 20 to 130 nm, in terms of superior transportability. The particles contained in the antistatic layer may be one type alone, or two or more types of particles may be used. When the antistatic layer contains two or more types of particles with different particle diameters, it is preferable that the antistatic layer contains at least one type of particle whose average particle diameter is within the above range, and it is more preferable that all two or more types of particles with different particle diameters have an average particle diameter within the above range.

[0040] The particle content in the antistatic layer is preferably 0.1 to 30% by mass, more preferably 1 to 25% by mass, and even more preferably 1 to 15% by mass, relative to the total mass of the antistatic layer, in terms of superior transportability.

[0041] (Conductive Compound) The antistatic layer preferably contains a conductive compound from the viewpoint of antistatic performance. The conductive compound is not particularly limited as long as it is a conductive compound, and may be a low molecular weight compound with a weight-average molecular weight (Mw) of 1000 or less, or a polymer compound with a weight-average molecular weight (Mw) of more than 1000. As the conductive compound, a conductive polymer compound with a weight-average molecular weight (Mw) of more than 1000 (hereinafter also referred to as "conductive polymer") is preferred in that it has better stretchability.

[0042] As the conductive polymer, any known conductive polymer can be used as appropriate, for example, polythiophene-based conductive polymers, polyaniline-based conductive polymers, and polypyrrole-based conductive polymers.

[0043] Examples of polythiophene-based conductive polymers include polythiophene, poly(3-alkylthiophene), and poly(3-thiophene-β-ethanesulfonic acid) and other polythiophene compounds having sulfonic acid groups, as well as mixtures of polyalkylenedioxythiophene and polystyrene sulfonate. Examples of polyalkylenedioxythiophene include polyethylenedioxythiophene, polypropylenedioxythiophene, and poly(ethylene / propylene)dioxythiophene. Among these, a mixture of polyalkylenedioxythiophene and polystyrene sulfonate is preferred, and a mixture of polyethylenedioxythiophene and polystyrene sulfonate (PEDOT / PSS) is more preferred. Examples of polyaniline-based conductive polymers include polyaniline, polymethylaniline, and polymethoxyaniline. Examples of polypyrrole-based conductive polymers include polypyrrole, poly3-methylpyrrole, and poly3-octylpyrrole.

[0044] The conductive compound may be used alone or in combination of two or more types. The content of the conductive compound is preferably 0.1 to 50% by mass, more preferably 0.3 to 30% by mass, and even more preferably 0.2 to 20% by mass, based on the total mass of the antistatic layer.

[0045] (Binder) The antistatic layer preferably contains a binder. Here, the binder refers to a compound other than the conductive compound. Examples of binders include polyester, polyurethane, acrylic resin, polyolefin, polyvinyl alcohol, and polyacrylonitrile butadiene. Polyester, polyurethane, acrylic resin, or polyolefin are preferred, and polyester, polyurethane, or acrylic resin are more preferred, as they can further reduce deformation due to foreign matter adhesion.

[0046] The binder contained in the antistatic layer may contain acidic groups. The inclusion of acidic groups in the binder of the antistatic layer facilitates the formation of the antistatic layer by a coating method using an aqueous dispersion containing particles. Examples of acidic groups include carboxylic acid groups, sulfo groups, and phosphate groups, with carboxylic acid groups or sulfo groups being preferred. The acidic groups may form acid anhydrides or be neutralized with at least one selected from alkali metals, organic amines, and ammonia.

[0047] Examples of polyesters include those contained in the polyester base material described above. The polyester may have the acid group described above. Preferably, the polyester is a polyester having a carboxylic acid group or a sulfo group, or a polyester without an acid group, more preferably a polyester having a carboxylic acid group or a sulfo group, and even more preferably a polyester having a sulfo group.

[0048] The polyurethane is not limited as long as it is a polymer having urethane bonds in its main chain, and known polyurethanes such as reaction products of polyisocyanate compounds and polyol compounds can be used. By adjusting the structure and flexibility of the polyol compound and polyisocyanate compound used as raw materials, the crosslinking reaction with the organic crosslinking agent can be adjusted, thereby improving the solvent resistance of the antistatic layer. It is preferable that the polyurethane contains a polyester structure in order to have superior solvent resistance of the antistatic layer. The polyurethane may also have the above-mentioned acid groups. Examples of commercially available acid group-containing polyurethanes include Hydran® AP-20, AP-40N and AP-201 (all manufactured by DIC Corporation), Takelac® W-605, W-5030 and W-5920 (all manufactured by Mitsui Chemicals, Inc.), Superflex® 210 and 130, and Elastron® H-3-DF, E-37 and H-15 (all manufactured by Daiichi Kogyo Seiyaku Co., Ltd.).

[0049] The acrylic resin is a resin containing constituent units derived from (meth)acrylate, and may also contain constituent units derived from vinyl monomers such as styrene. The acrylic resin preferably contains constituent units derived from (meth)acrylate having an alkyl group having 1 to 12 carbon atoms, and more preferably contains constituent units derived from (meth)acrylate having an alkyl group having 1 to 8 carbon atoms. The acrylic resin may have the above-mentioned acidic groups. The content of constituent units having acidic groups is preferably 10% by mass or less relative to all constituent units of the acrylic resin. By setting the content of constituent units having acidic groups within the above range, the acid value can be lowered, and the surface free energy can be adjusted to a desired range. The acid value of the acrylic resin is preferably 30 mgKOH / g or less, more preferably 20 mgKOH / g or less, and even more preferably 10 mgKOH / g or less. The acid value of the acrylic resin may be 0 mgKOH / g. Specific examples of acrylic resins include acrylic resins having oxazoline groups, which will be described later, including preferred embodiments.

[0050] Polyolefins are resins that contain olefin-derived structural units in their main chain. While there are no particular limitations on the olefin, alkenes having 2 to 6 carbon atoms are preferred, ethylene, propylene, or hexene are more preferred, and ethylene is even more preferred. The olefin-derived structural units in the polyolefin are preferably 50 to 99 mol%, and more preferably 60 to 98 mol%, relative to the total structural units of the polyolefin.

[0051] Polyolefins may have the above-mentioned acid groups. Examples of acid group-containing polyolefins include copolymers obtained by modifying the above-mentioned polyolefins with an acid-modifying component such as an unsaturated carboxylic acid or its anhydride. Examples of commercially available acid group-containing polyolefins include the Zaixen® series (manufactured by Sumitomo Seika Co., Ltd.), such as Zaixen AC, A, L, NC, and N; the Chemipearl® series (manufactured by Mitsui Chemicals, Inc.), such as Chemipearl S100, S120, S200, S300, S650, and SA100; the Hi-Tec® series (manufactured by Toho Chemical Co., Ltd.), such as Hi-Tec S3121 and S3148K; the Arrowbase® series (manufactured by Unitika Ltd.), such as Arrowbase SE-1013, SE-1010, SB-1200, SD-1200, SD-1200, DA-1010, and DB-4010; Hardlen AP-2, NZ-1004, and NZ-1005 (manufactured by Toyobo Co., Ltd.); and Sepolion G315 and VA407 (manufactured by Sumitomo Seika Co., Ltd.). Furthermore, acid-modified polyolefins described in paragraphs

[0022] to

[0034] of Japanese Patent Application Publication No. 2014-076632 can also be preferably used.

[0052] When the antistatic layer contains a polythiophene-based conductive polymer (more preferably PEDOT / PSS), it is preferable that the antistatic layer contains at least one selected from the group consisting of a binder having a sulfo group, a binder without an acid group, and a binder having a carboxylic acid group and an acid value of 10 mg KOH / g or less, as this facilitates the formation of a smooth surface with a low maximum protrusion height Sp, as described later. It is believed that using these binders prevents aggregation when mixed with the polythiophene-based conductive polymer, thus making the smooth surface even smoother. In particular, in the above case, it is preferable that the antistatic layer contains a binder having a sulfo group or a binder without an acid group, and more preferably a binder having a sulfo group.

[0053] Examples of binders having a carboxylic acid group and an acid value of 10 mg KOH / g or less include polyesters, polyurethanes, acrylic resins, and polyolefins that have a carboxylic acid group and an acid value of 10 mg KOH / g or less. The acid value of a binder having a carboxylic acid group may be 0 mg KOH / g. Examples of binders having a sulfo group include polyesters having a sulfo group, polyurethanes having a sulfo group, acrylic resins having a sulfo group, and polyolefins having a sulfo group. The acid value of a binder having a sulfo group is preferably 0 to 10 mg KOH / g. Examples of binders not having an acid group include polyesters, polyurethanes, acrylic resins, and polyolefins that do not have an acid group.

[0054] The acid value of the binder is determined by neutralization titration using an aqueous sodium hydroxide solution. Specifically, the binder is dissolved in a solvent and titrated with an aqueous sodium hydroxide solution using potentiometric assay to calculate the number of millimoles of acid contained in 1 g of solid binder. This value is then multiplied by the molecular weight of potassium hydroxide (KOH), which is 56.1.

[0055] The binder contained in the antistatic layer may be one type used alone, or two different types may be used in combination. The binder content in the antistatic layer is preferably 30 to 99.8% by mass, and more preferably 50 to 99.5% by mass, relative to the total mass of the antistatic layer.

[0056] (Conductive additive) The antistatic layer may contain a conductive additive, and it is preferable to include a conductive additive together with a conductive compound, as this makes it easier to adjust the surface resistance value of the surface of the antistatic layer. The conductive additive is not particularly limited, and examples include hydrophilic compounds. More specifically, examples include high-boiling point solvents such as dimethyl sulfoxide (boiling point: 189°C), dimethylformamide (boiling point: 153°C), N-methyl-2-pyrrolidone (boiling point: 202°C), and glycerin (boiling point: 290°C); ionic liquids; and alcohol compounds such as glycol compounds (ethylene glycol, diethylene glycol, etc.) and sugar alcohols (sorbitol, adonitol, arabitol, xylitol, etc.). Among these, alcohol compounds are preferred, and sugar alcohols are more preferred.

[0057] The conductive additive may be used alone or in combination of two or more types. When the antistatic layer contains a conductive additive, the content of the conductive additive is preferably 0.1 to 50% by mass, more preferably 0.2 to 30% by mass, and even more preferably 0.3 to 20% by mass, relative to the total mass of the antistatic layer.

[0058] The antistatic layer may contain additives other than particles, conductive compounds, binders, and conductive additives. Examples of additives included in the antistatic layer include surfactants, waxes, antioxidants, ultraviolet absorbers, colorants, strengthening agents, plasticizers, flame retardants, rust inhibitors, and mold inhibitors.

[0059] The antistatic layer preferably contains a surfactant, as this improves the smoothness of areas other than those where protrusions formed by particles are present. By including a surfactant in the antistatic layer, the smoothness of the above-mentioned areas is improved, and the surface roughness is reduced due to factors other than particles, making it easy to control the maximum protrusion height Sp of the smooth surface within a desired range.

[0060] The surfactant is not particularly limited, and examples include silicone-based surfactants, fluorine-based surfactants, and hydrocarbon-based surfactants, with hydrocarbon-based surfactants being preferred. Examples of hydrocarbon-based surfactants include anionic surfactants, nonionic surfactants, cationic surfactants, and amphoteric surfactants. Examples of anionic surfactants include alkyl sulfates, alkylbenzene sulfonates, alkyl phosphates, and fatty acid salts. Examples of nonionic surfactants include polyalkylene glycol-based surfactants such as polyalkylene glycol mono- or dialkyl ethers, polyalkylene glycol mono- or dialkyl esters, and polyalkylene glycol monoalkyl esters / monoalkyl ethers, as well as acetylene-based surfactants such as acetylene glycol and ethylene oxide adducts of acetylene glycol. Examples of cationic surfactants include primary to tertiary alkylamine salts and quaternary ammonium compounds. Examples of amphoteric surfactants include surfactants having both anionic and cationic parts in their molecule.

[0061] One type of surfactant may be used, or two or more types may be used in combination. The surfactant content is preferably 0.1 to 10% by mass relative to the total mass of the antistatic layer, and more preferably 0.1 to 5% by mass for superior surface smoothness.

[0062] (Physical properties of the antistatic layer) The thickness of the antistatic layer is preferably 1 to 500 nm, more preferably 10 to 200 nm, and even more preferably 20 to 100 nm, in that it reduces the haze of the film. The thickness of the antistatic layer is measured in accordance with the method for measuring the thickness of the polyester substrate described above.

[0063] - Indentation modulus The indentation modulus of the antistatic layer, as measured by an atomic force microscope (AFM), is preferably 1.0 to 10.0 GPa, more preferably 1.5 to 8.0 GPa, and even more preferably 1.5 GPa or more and less than 3.5 GPa. When the indentation modulus of the antistatic layer is below the above upper limit, deformation due to foreign matter is less likely to occur, and defects in the ceramic green sheet during manufacturing can be suppressed. The indentation modulus of the antistatic layer can be adjusted by the type and content of binders and additives contained in the antistatic layer. The method and measurement conditions for measuring the indentation modulus of the antistatic layer by AFM are described in the examples below.

[0064] - Maximum protrusion height Sp and average surface roughness Sa of the smooth surface The maximum protrusion height Sp of the smooth surface of this film is preferably 150 nm or less, more preferably 100 nm or less, even more preferably less than 60 nm, and particularly preferably 50 nm or less, in terms of reducing the likelihood of winding failures such as winding misalignment when the film is wound. The maximum protrusion height Sp of the smooth surface may be 1 nm or more, and is preferably 5 nm or more, more preferably 10 nm or more, and even more preferably 20 nm or more, in terms of improving transportability and reducing winding failures. The average surface roughness Sa of the smooth surface is preferably 5 nm or less, and more preferably 3 nm or less. The lower limit may be 0 nm or more.

[0065] The maximum protrusion height Sp and average surface roughness Sa of the smooth surface can be adjusted, for example, by the particle size and content of the particles contained in the antistatic layer, the type and content of the binder and surfactant contained in the antistatic layer, and the thickness of the antistatic layer.

[0066] The maximum protrusion height Sp and average surface roughness Sa of the polyester film surface (smooth surface and peel surface) are determined by measuring the surface of the polyester film using an optical interferometer (for example, "Vertscan 3300G Lite" manufactured by Hitachi High-Tech Corporation), and then analyzing the data using the built-in data analysis software. The specific measurement method and conditions are described in the examples below.

[0067] The method for forming the antistatic layer is not particularly limited, but it is preferable that the antistatic layer is formed by in-line coating. More specifically, it is preferable that the layer is formed by curing an antistatic layer-forming composition by in-line coating. The method for forming the antistatic layer will be described in more detail later in the section on [Method for Manufacturing Polyester Film].

[0068] <Release Layer> This film has a release layer. The release layer is formed, for example, as a layer constituting the release surface of a polyester film. After a component such as a ceramic green sheet is formed on the release surface of the polyester film, it is peeled off from the release surface. The release layer may be provided in contact with the polyester substrate without other layers in between, or it may be provided via other layers. It is preferable that the release layer is in contact with the polyester substrate. It is preferable that the release layer is the outermost layer of this film. That is, it is preferable that the surface of the release layer is the release surface.

[0069] The release layer preferably contains a release agent. The release agent is not particularly limited and examples include silicone resins, fluororesins, alkyd resins, acrylic resins, urethane resins, various waxes, and aliphatic olefins. When the polyester film is a release film for manufacturing ceramic green sheets, as described later, silicone resins, acrylic resins, or urethane resins are preferred in terms of the release properties of the ceramic green sheet, and acrylic resins or urethane resins are more preferred.

[0070] (Acrylic resin) The acrylic resin contained in the release layer may or may not be crosslinked. The acrylic resin contained in the release layer is preferably crosslinked in order to have better release properties of the release surface, and is preferably a crosslinked body formed by the reaction of acrylic resin A having a reactive group A and crosslinking agent B having a reactive group B that can react with reactive group A.

[0071] Furthermore, the acrylic resin contained in the release layer is -Si(R) ３ Preferably, it has a structure represented by -Si(R) in the side chain. ３ It is more preferable to have a structure represented by -Si(R)３ In the formula, each R independently represents an alkyl group or an aryl group. Examples of the alkyl group for R include linear alkyl groups having 1 to 10 carbon atoms (preferably 1 to 5 carbon atoms), branched or cyclic alkyl groups having 3 to 12 carbon atoms (preferably 3 to 6 carbon atoms). The number of carbon atoms of the aryl group for R is preferably 6 to 30, more preferably 6 to 20, and even more preferably 6 to 12. Among them, R is preferably an alkyl group, more preferably a linear alkyl group having 1 to 5 carbon atoms, even more preferably a methyl group, an ethyl group, a propyl group, an n-butyl group, an isopropyl group, an isobutyl group, or a tert-butyl group, and particularly preferably a methyl group, an ethyl group, a propyl group, or an n-butyl group, in terms of having better peelability of the peeling surface. A plurality of Rs may be the same or different.

[0072] Further, the acrylic resin contained in the release layer preferably has a siloxane bond. The siloxane bond preferably has a structure represented by -[O-Si(R) ２ -. ２ In -[O-Si(R) ３ , R has the same meaning as R in -Si(R) ２ including preferred embodiments. The acrylic resin more preferably has two or more siloxane bonds. In terms of having better peelability of the peeling surface, the acrylic resin more preferably has a linear polysiloxane structure. The linear polysiloxane structure is a structure represented by -[Si(R) ｍ -O] ３ -. R has the same meaning as R in the structure represented by -Si(R) ３ including preferred embodiments, and m represents an integer of 2 or more. Among them, the acrylic resin particularly preferably has both -Si(R) ３ and a siloxane bond. Structures having both -Si(R) ３ and a siloxane bond include a structure represented by -Si[-O-Si(R) ｎ R ３－ｎ , and a structure represented by -[Si(R) ２ -O]-Si(R) ｍ ３At least one selected from the group consisting of structures represented by -[Si(R) ２ -O] ｍ -Si(R) ３ A linear structure represented by is more preferred. R and m are the same as R and m above, including in preferred embodiments. n is 2 or 3 (preferably 3). As described above, -Si(R) ３ The acrylic resin having at least one (more preferably both) of the siloxane bond may be crosslinked or not, but it is preferable that it be crosslinked, and more preferably that it is a crosslinked product of acrylic resin A and crosslinking agent B.

[0073] The following provides a more detailed explanation of the crosslinked product of acrylic resin A and crosslinking agent B.

[0074] Acrylic resin A Acrylic resin A is a compound that contains constituent units derived from (meth)acrylate and has a reactive group A. Examples of reactive group A in acrylic resin A include a reactive group comprising at least one selected from the group consisting of a carboxyl group, a carboxylic acid anhydride group, a carboxylic acid base, and a hydroxyl group. A carboxyl group or a carboxylic acid base, which is a salt of a carboxyl group, is preferred as the reactive group A because it provides better peelability of the peeled surface.

[0075] Acrylic resin A is -Si(R) ３ Preferably, it has at least one of the siloxane bond, and -Si(R) ３ It is more preferable to have both -Si(R) and siloxane bonds. Acrylic resin A has -Si(R) ３ For specific examples and preferred embodiments of the siloxane bond, please refer to the -Si(R) bond present in the above-mentioned acrylic resin. ３ And it is similar to a siloxane bond.

[0076] The constituent unit acrylic resin A derived from monomer A1 preferably contains constituent units derived from monomer A1, which is an acrylic monomer having a siloxane bond. The above acrylic monomer refers to a concept that includes both (meth)acrylic acid ester and (meth)acrylic acid. (Meth)acrylic acid refers to a concept that includes methacrylic acid and acrylic acid. Monomer A1 is preferably a (meth)acrylic acid ester having a siloxane bond. Also, monomer A1 is -Si(R) ３ It is also preferable that the monomer A1 has a group represented by -Si[-O-Si(R) ３ ] ｎ R ３－ｎ A group represented by -[Si(R) ２ -O] ｍ -Si(R) ３ Preferably, it has at least one group selected from the group consisting of groups represented by -[Si(R) ２ -O] ｍ -Si(R) ３ It is more preferable to have a group represented by . R, n, and m are as described above.

[0077] The molecular weight of monomer A1 is preferably 5000 or less, more preferably 4000 or less, and even more preferably 3000 or less, in terms of superior peelability of the peeled surface. The lower limit is often 100 or more, preferably 500 or more, and more preferably 700 or more. The molecular weight of monomer A1 can be measured by MALDI-MS (matrix-assisted laser desorption / ionization mass spectrometry). Here, if monomer A1 is a mixture of monomers with different molecular weights, the peak with the highest intensity detected by the MS spectrum (mass spectrometry) is read, and that molecular weight is taken as the molecular weight of monomer A1.

[0078] The monomer A1 is preferably a compound represented by the following formula (A1-1): CH ２ = C(R １１ )C(O)O-L １１ -Rh (A1-1)

[0079] In formula (A1-1), R １１This is either a hydrogen atom or a methyl group.

[0080] In formula (A1-1), L １１ L is an alkylene group which may have substituents. １１ The alkylene group in this compound may be linear, branched, or cyclic, but linear or branched is preferred, and linear is more preferred. １１ The number of carbon atoms in the alkylene group is preferably 1 to 10, more preferably 1 to 7, and even more preferably 1 to 5. Specific examples of substituents that the alkylene group may have include halogen atoms, alkoxy groups (preferably with 1 to 5 carbon atoms), and carboxyl groups. Among these, L １１ The alkylene group is preferably one without substituents, and a propylene group, an ethylene group, or a methylene group is more preferable.

[0081] In formula (A1-1), Rh is a substituent having a siloxane bond. Rh is -Si(R) ３ It is also preferable to have one or more groups represented by . In particular, Rh is -Si[-O-Si(R) ３ ] ｎ R ３－ｎ A group represented by, or -[Si(R) ２ -O] ｍ -Si(R) ３ It is preferable that the group is represented by -[Si(R) ２ -O] ｍ -Si(R) ３ It is more preferable that the group be represented by . R, n, and m are as described above.

[0082] Specific examples of monomer A1 include organosilyl group-containing monomers such as (meth)acrylate 3-[tris(trimethylsilyloxy)silyl]propyl, Cyraprene FM-0711 (manufactured by JNC Corporation), Cyraprene FM-0721 (manufactured by JNC Corporation), Cyraprene FM-0725 (manufactured by JNC Corporation), Cyraprene TM-0701T (manufactured by JNC Corporation), X-22-174ASX (manufactured by Shin-Etsu Chemical Co., Ltd.), X-22-174BX (manufactured by Shin-Etsu Chemical Co., Ltd.), KF-2012 (manufactured by Shin-Etsu Chemical Co., Ltd.), X-22-2426 (manufactured by Shin-Etsu Chemical Co., Ltd.), and X-22-2404 (manufactured by Shin-Etsu Chemical Co., Ltd.).

[0083] When acrylic resin A has constituent units derived from monomer A1, the content of constituent units derived from monomer A1 is preferably 10 to 90% by mass, more preferably 15 to 85% by mass, and even more preferably 20 to 80% by mass, relative to the total constituent units (100% by mass) of acrylic resin A. If the content of constituent units derived from monomer A1 is 10% by mass or more, the peelability of the sheet formed on the surface of the release layer is better. Furthermore, if the content of constituent units derived from monomer A1 is 90% by mass or less, the coating properties of the composition containing organic solvents are better.

[0084] The acrylic resin A, which is a constituent unit derived from monomer A2, preferably contains a constituent unit derived from monomer A2 that includes at least one of a carboxyl group, a carboxylic acid anhydride group, and a carboxylic acid base. This improves the water solubility and curability of the resin. It is preferable that monomer A2 does not have a siloxane bond. When acrylic resin A contains a constituent unit derived from monomer A2, a crosslinked product of acrylic resin A and crosslinking agent B can be formed by the reaction of at least one selected from the group consisting of a carboxyl group, a carboxylic acid anhydride group, and a carboxylic acid base with a crosslinking agent B (preferably the reactive group B described later). Examples of carboxylic acid anhydride groups include groups based on acid anhydrides such as maleic anhydride and itaconic anhydride. Examples of carboxylic acid bases include alkali metal salts of carboxyl groups, organic amine salts of carboxyl groups, and ammonium salts of carboxyl groups.

[0085] Examples of monomer A2 include carboxyl group-containing monomers such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, and crotonic acid, and their salts (e.g., sodium salts, potassium salts, ammonium salts, and tertiary amine salts); monomers of acid anhydrides such as maleic anhydride and itaconic anhydride; and (meth)acrylic acid esters having a carboxyl group or a carboxylic acid base.

[0086] Specific examples of (meth)acrylic acid esters having a carboxyl group or a carboxylic acid base include carboxyl group-containing (meth)acrylic acid esters such as 2-methacryloyloxyethyl succinic acid, 2-acryloyloxyethyl hexahydrophthalic acid, and ω-carboxy-polycaprolactone monoacrylate.

[0087] When acrylic resin A has constituent units derived from monomer A2, the content of constituent units derived from monomer A2 is preferably 1 to 40% by mass, more preferably 3 to 35% by mass, and even more preferably 5 to 30% by mass, relative to the total constituent units (100% by mass) of acrylic resin A. If the content of constituent units derived from monomer A2 is 5% by mass or more, the water solubility and curability of the resin are improved. Furthermore, if the content of constituent units derived from monomer A2 is 30% by mass or less, the release properties of the sheet formed on the surface of the release layer are improved.

[0088] The acrylic resin A, which is a constituent unit derived from monomer A3, preferably further contains constituent units derived from monomer A3 having a ClogP value of 0.8 or higher. This results in superior peelability of the peel surface. It is preferable that monomer A3 does not have any siloxane bond, carboxyl group, carboxylic acid anhydride group, or carboxylic acid base.

[0089] The ClogP value of monomer A3 is preferably 1.0 or higher, more preferably 1.2 or higher, in terms of superior peelability of the peeled surface. The ClogP value of monomer A3 is preferably 6.0 or lower, more preferably 5.0 or lower, and even more preferably 4.0 or lower, in terms of suitability for synthesis of acrylic resin A. Here, the ClogP value is the value obtained by calculation of the common logarithm logP of the partition coefficient P to 1-octanol and water. Known methods and software can be used to calculate the ClogP value, but unless otherwise specified, this invention uses the ClogP program incorporated in Cambridge Soft's ChemBioDraw Ultra 13.0.

[0090] Monomer A3 is preferably copolymerizable with monomers A1 and A2, and preferably has polymerizable groups such as a (meth)acryloyloxy group and a vinyl group. The term (meth)acryloyloxy group refers to a concept that includes both an acryloyloxy group and a methacryloyloxy group.

[0091] Specific examples of monomer A3 include (meth)acrylic acid esters such as 2-methoxyethyl acrylate (MEA), 2-hydroxy-3-phenoxypropyl acrylate (HPPA), ethylene glycol monoacetate monomethacrylate (EGMM), t-butyl acrylate (tBA), benzyl methacrylate (BnMA), phenoxyethyl acrylate (PEA), n-butyl acrylate (nBA), cyclohexyl acrylate (CyHA), tetrahydrofurfuryl methacrylate (THFMA), cyclohexyl methacrylate (CyHMA), methyl methacrylate (MMA), caprolactone-modified methacrylate, 2-acryloyloxyethyl-2-hydroxyethyl phthalic acid, dicyclopentanyl methacrylate, isobornyl methacrylate, etc.; styrene (St), α-methylstyrene; and the like.

[0092] When acrylic resin A has constituent units derived from monomer A3, the content of constituent units derived from monomer A3 is preferably 5 to 30% by mass, more preferably 7 to 25% by mass, and even more preferably 10 to 20% by mass, relative to the total constituent units (100% by mass) of monomer A3. If the content of constituent units derived from monomer A3 is 5% by mass or more, the peelability of the peeled surface is better. Furthermore, if the content of constituent units derived from monomer A3 is 30% by mass or less, the peelability of the peeled surface is better.

[0093] ...The constituent units of acrylic resin A derived from other monomers may have constituent units derived from monomers other than monomers A1 to A3 (hereinafter also referred to as "other monomers").

[0094] Another specific example of a monomer is a (meth)acrylic acid ester containing a polyalkylene oxide chain. Specific examples of polyalkylene oxide chains include polymethylene oxide, polyethylene oxide, polypropylene oxide, and polybutylene oxide. The number of repeating units in the polyalkylene oxide chain is preferably 3 to 100.

[0095] Examples of (meth)acrylic acid esters containing polyalkylene oxide chains include methoxypolyethylene glycol (meth)acrylate, ethoxypolyethylene glycol (meth)acrylate, methoxypolypropylene glycol (meth)acrylate, and ethoxypolypropylene glycol (meth)acrylate.

[0096] Specific examples of monomers other than (meth)acrylic acid esters containing polyalkylene oxide chains include: hydroxyl group-containing monomers such as 2-hydroxymethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, glycerol monomethacrylate, and 4-hydroxybutyl (meth)acrylate; epoxy group-containing monomers such as glycidyl (meth)acrylate and allyl glycidyl ether; sulfonic acid group-containing monomers such as styrene sulfonic acid and their salts; phosphate group-containing monomers such as 2-methchloroyloxyethyl acid phosphate and their salts; Examples of amide group-containing monomers include (meth)acrylamide, N-alkyl(meth)acrylamide, N,N-dialkyl(meth)acrylamide, N,N-dialkyl(meth)acrylate (examples of alkyl groups: methyl group, ethyl group, n-butyl group, isobutyl group, etc.), acryloylmorpholine, N-methylol(meth)acrylamide, N-isopropylacrylamide, diacetone acrylamide, and N-phenyl(meth)acrylamide; vinyl isocyanates, allyl isocyanates, vinyl methyl ethers, vinyl ethyl ethers, vinyl trialkoxysilanes, alkyl maleic acid monoesters, alkyl fumaric acid monoesters, alkyl itaconic acid monoesters, (meth)acrylonitrile vinylidene chloride, ethylene, propylene, vinyl chloride, vinyl acetate, and butadiene.

[0097] When acrylic resin A has constituent units derived from other monomers, the content of constituent units derived from other monomers is preferably 1 to 30% by mass, more preferably 2 to 20% by mass, and even more preferably 5 to 15% by mass, relative to the total constituent units (100% by mass) of acrylic resin A.

[0098] ...Preferred embodiments of acrylic resin A One preferred embodiment of acrylic resin A is an embodiment that includes constituent units derived from monomer A1 and constituent units derived from monomer A2, and one more preferred embodiment is an embodiment that includes constituent units derived from monomer A1, constituent units derived from monomer A2, and constituent units derived from monomer A3.

[0099] The acid value of acrylic resin A is preferably 0.3 to 6.0 mmol / g, more preferably 0.5 to 4.5 mmol / g, even more preferably 0.5 to 3.0 mmol / g, and particularly preferably 0.5 to 2.5 mmol / g. The hydroxyl value of acrylic resin A is preferably 0 to 3.0 mmol / g, more preferably 0 to 2.5 mmol / g, and even more preferably 0 to 2.0 mmol / g. If the acid value or hydroxyl value is above the above lower limit, the water solubility and curability of acrylic resin A are better. If the acid value or hydroxyl value is below the above lower limit, the peelability of the peeled surface is better.

[0100] The weight-average molecular weight (Mw) of acrylic resin A is preferably 5,000 to 100,000, more preferably 7,000 to 80,000, and even more preferably 10,000 to 50,000. If the Mw of acrylic resin A is 5,000 or higher, the suitability for coating and manufacturing the release layer is better. Furthermore, if the Mw of acrylic resin A is 100,000 or lower, the peelability of the release surface is better. The weight-average molecular weight (Mw) of acrylic resin A is measured by gel permeation chromatography (GPC).

[0101] Acrylic resin A may contain only one type or two or more types. The content of acrylic resin A is preferably 20 to 90% by mass, more preferably 30 to 80% by mass, and even more preferably 50 to 80% by mass, based on the total mass of the release layer. When the release layer contains a crosslinked product of acrylic resin A and crosslinking agent B described later, it is preferable that the content of the structure derived from acrylic resin A satisfies the above range.

[0102] Crosslinking agent B Crosslinking agent B is a compound having a reactive group B that can react with the reactive group A of acrylic resin A. Crosslinking agent B is preferably water-soluble in order to easily form a release layer by in-line coating. A crosslinked product of acrylic resin A and crosslinking agent B can be formed, for example, by the reaction between the reactive group A of acrylic resin A and the reactive group B of crosslinking agent B when forming a release layer using a composition containing acrylic resin A and crosslinking agent B.

[0103] When acrylic resin A has a carboxyl group, a carboxylic acid anhydride group, or a carboxylic acid base, the reactive group B is preferably an oxazoline group, a carbodiimide group, an epoxy group, a methylol group, an isocyanate group, or a blocked isocyanate group, in terms of excellent reactivity with the carboxyl group, etc. Among these, the oxazoline group, epoxy group, or carbodiimide group is more preferred in terms of superior peelability of the peeled surface, the oxazoline group or epoxy group is even more preferred, and the oxazoline group is particularly preferred. Here, a blocked isocyanate group means an isocyanate group that has been blocked by a blocking agent (for example, a compound having an active hydrogen group). When acrylic resin A has a hydroxyl group, the reactive group B is preferably an isocyanate group, a methylol group, or a blocked isocyanate group, in terms of excellent reactivity with the hydroxyl group.

[0104] The crosslinking agent B having the reactive group B is not particularly limited, and examples include one or more crosslinking agents selected from the group consisting of oxazoline compounds, isocyanate compounds, carbodiimide compounds, melamine compounds, and epoxy compounds. The isocyanate compound may be a compound having a blocked isocyanate group in which the isocyanate group is blocked by a blocking agent. Among these, oxazoline compounds, epoxy compounds, or carbodiimide compounds are preferred in terms of superior peelability of the peeled surface, oxazoline compounds or epoxy compounds are more preferred, and oxazoline compounds are even more preferred.

[0105] ...Oxazoline compounds The oxazoline compounds are not particularly limited as long as they are compounds having an oxazoline group, and may be low molecular weight compounds with a weight-average molecular weight (Mw) of 1000 or less, or high molecular weight compounds with a weight-average molecular weight (Mw) of more than 1000, but high molecular weight compounds are preferred in that they have superior peelability of the peeled surface.

[0106] Examples of low molecular weight compounds having an oxazoline group include 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2-isopropenyl-2-oxazoline, 2-isopropenyl-4-oxazoline, 2-isopropenyl-4-methyl-2-oxazoline, 2-isopropenyl-5-methyl-2-oxazoline, 2-isopropenyl-5-ethyl-2-oxazoline, 2,2'-bis-(2-oxazoline), 2,2'-methylene-bis-(2-oxazoline), 2,2'-ethylene-bis-(2-oxazoline), and 2,2'-trimethylene-bis- Examples include (2-oxazoline), 2,2'-tetramethylene-bis-(2-oxazoline), 2,2'-hexamethylene-bis-(2-oxazoline), 2,2'-octamethylene-bis-(2-oxazoline), 2,2'-ethylene-bis-(4,4'-dimethyl-2-oxazoline), 2,2'-p-phenylene-bis-(2-oxazoline), 2,2'-m-phenylene-bis-(2-oxazoline), 2,2'-m-phenylene-bis-(4,4'-dimethyl-2-oxazoline), bis-(2-oxazolinylcyclohexane) sulfide, and bis-(2-oxazolinylnorbornane) sulfide.

[0107] When the oxazoline compound is a polymer compound, it can be any polymer compound having an oxazoline group, for example, a copolymer containing the above-mentioned low-molecular-weight compound having an oxazoline group as a constituent unit.

[0108] The polymer compound having an oxazoline group is preferably an acrylic resin having an oxazoline group, and more preferably an acrylic resin containing both an oxazoline group and a polyalkylene oxide chain. The inclusion of a polyalkylene oxide chain in the polymer compound having an oxazoline group improves the water solubility of crosslinking agent B, resulting in superior in-line coating suitability.

[0109] Examples of polyalkylene oxide chains include polymethylene oxide, polyethylene oxide, polypropylene oxide, and polybutylene oxide. The repeating units of the polyalkylene oxide chain are preferably 3 to 100.

[0110] Examples of (meth)acrylic acid esters containing polyalkylene oxide chains include methoxypolyethylene glycol (meth)acrylate, ethoxypolyethylene glycol (meth)acrylate, methoxypolypropylene glycol (meth)acrylate, and ethoxypolypropylene glycol (meth)acrylate.

[0111] The polymer compound having an oxazoline group may also contain structural units derived from the low molecular weight compound having the oxazoline group, and structural units derived from other monomers other than those derived from (meth)acrylic acid esters containing polyalkylene oxide chains.

[0112] Other monomers include, for example, alkyl group-containing monomers such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and cyclohexyl (meth)acrylate; hydroxyl-containing monomers such as 2-hydroxyethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and glycerol monomethacrylate; epoxy group-containing monomers such as glycidyl (meth)acrylate and allyl glycidyl ether; styrene sulfonic acid, potassium 3-sulfopropyl methacrylate, 2-acrylamide Examples include sulfo group-containing monomers such as mido-2-methylpropanesulfonic acid; amide group-containing monomers such as (meth)acrylamide, N-alkyl(meth)acrylamide, N,N-dialkyl(meth)acrylamide, N,N-dialkyl(meth)acrylate (examples of alkyl groups: methyl group, ethyl group, n-butyl group, isobutyl group, etc.), acryloylmorpholine, N-methylol(meth)acrylamide, and N-phenyl(meth)acrylamide; vinyl isocyanate, allyl isocyanate, styrene, α-methylstyrene, vinyl methyl ether, vinyl ethyl ether, vinyl trialkoxysilane, alkyl maleic acid monoester, alkyl fumaric acid monoester, alkyl itaconic acid monoester, (meth)acrylonitrile vinylidene chloride, ethylene, propylene, vinyl chloride, vinyl acetate, butadiene, and the compound represented by the above formula (A1-1). Among these, the compound represented by the above formula (A1-1) is preferred as the other monomer because it exhibits superior peelability of the peeled surface.

[0113] High-molecular-weight compounds containing oxazoline groups are preferably water-soluble from an environmental perspective.

[0114] The weight-average molecular weight (Mw) of the polymer compound having an oxazoline group is not particularly limited, but is preferably 3000 or more, more preferably 5000 to 200000, and even more preferably 7000 to 150000. The weight-average molecular weight (Mw) is measured according to the method for measuring the weight-average molecular weight of acrylic resins.

[0115] The polymer compound having an oxazoline group may be a commercially available product. Examples of commercially available products include Epocross (registered trademark, hereinafter the same) K-2010E, Epocross K-2020E, Epocross K-2030E, Epocross WS-700, and Epocross WS-300 (all manufactured by Nippon Shokubai Co., Ltd.).

[0116] ...Isocyanate compounds Isocyanate compounds are compounds having an isocyanate group or a blocked isocyanate group. Blocked isocyanate compounds (i.e., compounds having a blocked isocyanate group) are preferred. Blocked isocyanate compounds are compounds in which the isocyanate group of a polyisocyanate is protected (i.e., blocked) with a blocking agent, and are included in isocyanate compounds in this specification. Examples of blocking agents in blocked isocyanates include ester compounds, phenol compounds, alcohol compounds, oxime compounds, mercaptan compounds, lactam compounds, amine compounds, acid amide compounds, pyrazole compounds, triazole compounds, and bisulfite compounds.

[0117] Carbodiimide compounds are compounds having a carbodiimide group. Carbodiimide compounds can be synthesized by conventionally known methods. For example, the condensation reaction of diisocyanate compounds is used. The diisocyanate compound is not particularly limited and may be any of aromatic diisocyanates, aliphatic diisocyanates, and alicyclic diisocyanates. Specific examples of aromatic diisocyanates, aliphatic diisocyanates, and alicyclic diisocyanates are the same as the specific examples of diisocyanates described in the section on isocyanate compounds. The carbodiimide equivalent (mass [g] of the carbodiimide compound to give 1 mole of carbodiimide group) is preferably 100 to 1000 g / mol, more preferably 250 to 800 g / mol, and even more preferably 300 to 700 g / mol.

[0118] ...Melamine compounds In this specification, melamine compounds refer to melamine and -NH in melamine. ２ This refers to melamine derivatives in which the hydrogen atom of the base is substituted by a substituent. There are no particular limitations on the melamine-based compound, but it is obtained by condensing melamine and formaldehyde, and the -NH in melamine. ２ One or more hydrogen atoms of the group are methylol groups (-CH ２ Examples include methylolmelamine compounds substituted with OH). Furthermore, etherified methylolmelamine compounds are also included, which are obtained by dehydrating and condensing the above-mentioned methylolmelamine with an alcohol compound to form an ether. Specifically, examples of melamine compounds include trimethylolmelamine, hexamethylolmelamine, trimethoxymethylmelamine, and hexamethoxymethylmelamine.

[0119] Epoxy compounds are not particularly limited as long as they are compounds having epoxy groups. Epoxy compounds preferably have two or more epoxy groups in their molecule. The epoxy groups in the epoxy compound may be epoxy groups contained in a glycidyl group, or epoxy groups contained in an alicyclic epoxy group. An alicyclic epoxy group refers to a group such as a 3,4-epoxycyclohexyl group.

[0120] Commercial epoxy compounds may be used. Examples of commercially available epoxy compounds include Cyclomer® M100, Celoxide® 2000, Celoxide® 2021P, 2081, Epolid® GT401, and EHPE® 3150 (manufactured by Daicel Corporation).

[0121] The epoxy compound is not particularly limited as long as it is a compound having an epoxy group. It may be a low molecular weight compound with a weight-average molecular weight (Mw) of 1000 or less, or a high molecular weight compound with a weight-average molecular weight (Mw) of more than 1000. However, a high molecular weight compound is preferable in that it has superior peelability of the peeled surface.

[0122] ...Preference embodiment of crosslinking agent B The crosslinking agent B is preferably an acrylic resin having a reactive group B in its side chain, in that it is superior in terms of peelability of the peeled surface. Specific examples of acrylic resins having a reactive group B in its side chain include the above-mentioned polymer compounds having an oxazoline group (specifically, copolymers comprising a structural unit derived from the above-mentioned low-molecular-weight compound having an oxazoline group and a structural unit derived from a (meth)acrylic acid ester containing a polyalkylene oxide chain), and the above-mentioned polymer compounds having an epoxy group (specifically, copolymers comprising a structural unit derived from a compound having an epoxy group and a structural unit derived from a (meth)acrylic acid ester containing a polyalkylene oxide chain). Among these, the acrylic resin having a reactive group B in its side chain is preferably the above-mentioned polymer compound having an oxazoline group, in that it is superior in terms of peelability of the peeled surface.

[0123] The crosslinking agent B may be of one type or of two or more types. The content of crosslinking agent B is preferably 1 to 80% by mass, more preferably 1 to 70% by mass, even more preferably 1 to 60% by mass, and still more preferably 10 to 50% by mass, relative to the total mass of the release layer, in terms of the reactivity of the acrylic resin A. When the release layer contains a crosslinked product of acrylic resin A and crosslinking agent B described later, it is preferable that the content of the structure derived from crosslinking agent B satisfies the above range.

[0124] - Preferred embodiment of the crosslinked body: The release layer preferably contains a crosslinked body of acrylic resin A having siloxane bonds and crosslinking agent B. In particular, it is more preferable that the acrylic resin A having siloxane bonds is in the above preferred embodiment, and that at least one of the above preferred embodiment is the case where the acrylic resin A having siloxane bonds is in the above preferred embodiment and the crosslinking agent B is in the above preferred embodiment.

[0125] When the release layer contains a crosslinked acrylic resin A and crosslinking agent B, the content of the crosslinked acrylic resin A and crosslinking agent B is preferably 98 to 100% by mass, and more preferably 98.5 to 100% by mass, relative to the total mass of the release layer, in terms of having superior release properties of the release surface.

[0126] The presence of cross-linked materials (such as acrylic resin cross-linked materials and urethane resin cross-linked materials described later) in the release layer can be confirmed by measuring the tape peeling force before and after the following abrasion test and observing the change in the measured peeling force. Specifically, if the rate of change in peeling force before and after the following abrasion test is 20% or less, it is determined that the release layer contains resin cross-linked materials. Abrasion test: The surface of the release layer of the polyester film is subjected to a load of 100 g / cm using a cloth soaked in a mixed solution of ethanol and toluene in a mass ratio of 1:1. ２Under these conditions, rub the surface back and forth five times in one direction within the plane, and then rub it back and forth five times in a direction perpendicular to the above direction. Confirmation of peeling force: An adhesive tape (manufactured by Nitto Denko, No. 31B) is attached to the surface of the release layer of the polyester film before the abrasion test. The peeling force when the adhesive tape is peeled off at a peeling angle of 180 degrees and a peeling speed of 300 mm / min is measured and defined as the standard adhesive tape peeling force (f0). Similarly, an adhesive tape is attached to the surface of the release layer of the polyester film after the abrasion test, and the peeling force is measured and defined as the post-abrasion test adhesive tape peeling force (f). From the obtained standard adhesive tape peeling force (f0) and post-abrasion test adhesive tape peeling force (f), the rate of change of peeling force is calculated using the following formula (I). Rate of change of peeling force (%) = [{(f) - (f0)} / (f0)] × 100 ... (I)

[0127] (Urethane resin) The urethane resin included in the release layer is not limited as long as it is a polymer having urethane bonds in its main chain, and known urethane resins such as the reaction products of polyols and polyisocyanates described later can be used.

[0128] The urethane resin preferably has siloxane bonds, and also -Si(R) ３ It is more preferable to have a structure represented by a siloxane bond and -Si(R) ３ It is more preferable to have both of the structures represented by . The siloxane bond in the urethane resin is synonymous with the siloxane bond in the acrylic resin, including in the preferred embodiment. -Si(R) in the urethane resin ３ The structure represented by also includes, in preferred embodiments, the acrylic resin possesses -Si(R) ３ This is synonymous with the structure represented by .

[0129] A urethane resin having siloxane bonds may have siloxane bonds in the main chain of the urethane resin, or it may have siloxane bonds in the side chains of the urethane resin. It is preferable that the siloxane bonds be in the side chains of the urethane resin because the siloxane bonds tend to localize on the surface. Examples of urethane resins having siloxane bonds include reaction products of a polyol, a polyisocyanate, and a compound having a reactive functional group and a siloxane structure (hereinafter also referred to as a "reactive silicone compound").

[0130] Examples of polyols include polyether polyols, polyester polyols, polycaptolactone polyols, polycarbonate polyols, and acrylic polyols. Examples of polyester polyols include polycondensates of dibasic acids such as terephthalic acid, adipic acid, and succinic acid with polyols such as ethylene glycol, polyoxyethylene glycol, and 1,6-hexanediol. Examples of polycaprolactone polyols include compounds obtained by ring-opening polymerization of polyols using captolactones such as ε-caprolactone as initiators. Examples of polycarbonate polyols include reaction products of glycols such as ethylene glycol, 1,6-hexanediol, and bisphenol A with carbonates such as ethylene carbonate and diphenyl carbonate. Examples of acrylic polyols include copolymers of acrylic acid derivatives containing hydroxyl groups, such as hydroxyethyl acrylate, hydroxyethyl methacrylate, and hydroxybutyl acrylate, with acrylic acid, methacrylic acid, and acrylic acid esters.

[0131] Any compound having two or more isocyanate groups in one molecule can be used as the polyisocyanate. Examples include monomers such as hexamethylene diisocyanate, trimethylene diisocyanate, 1,4-cyclohexane diisocyanate, bis(4-isocyanatophenyl)methane, toluene-2,4-diisocyanate, 4,4'-toluene diisocyanate, p-phenylenediisocyanate, m-phenylenediisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, and 4,4'-diphenyl isocyanate. In addition, polymers such as dimers, biuretes, and isocyanurates derived from the above monomers, as well as adducts obtained by adding a polyisocyanate monomer to a low molecular weight polyol such as trimethylolpropane, can also be used. As for the polyisocyanate, compounds having two isocyanate groups in the molecule are preferred because the reaction can be easily controlled.

[0132] The reactive silicone compound used in the synthesis of urethane resins having siloxane bonds is a compound having a reactive functional group and a siloxane structure that reacts with a polyol or polyisocyanate. The siloxane bond in the reactive silicone compound is synonymous with the siloxane bond in acrylic resin, including in preferred embodiments. The reactive silicone compound is -Si(R) ３ It is preferable to further have the structure represented by . The reactive silicone compound has -Si(R) ３ The structure represented by, including preferred embodiments, is a structure in which the acrylic resin possesses -Si(R) ３ This is synonymous with the structure represented by .

[0133] The reactive functional groups of the reactive silicone compound can be those that react with polyols or polyisocyanates, such as amino groups, epoxy groups, hydroxyl groups, and carboxyl groups. The reactive functional groups react with the hydroxyl groups of the polyol or the isocyanate groups of the polyisocyanate to obtain a urethane resin having siloxane bonds.

[0134] Examples of reactive silicone compounds include amino-modified silicones (such as "DOWSILBY16-205" and "DOWSILFZ-3760" from Dow Toray Industries, Inc., and "X-22-161A" and "PAM-E" from Shin-Etsu Chemical Co., Ltd.), and epoxy-modified silicones (such as "DOWSILBY16-839Fluid" and "DOWSILSF8" from Dow Toray Industries, Inc.) Examples include "421 Fluid," "X-22-163" and "KF-105" manufactured by Shin-Etsu Chemical Co., Ltd., and hydroxyl-modified silicones ("DOWSILBY16-201" and "DOWSILSF8427 Fluid" manufactured by Dow Toray Industries, Ltd., "X-22-176DX" and "X-22-176F" manufactured by Shin-Etsu Chemical Co., Ltd., and "Cylaplane® FM DA-26" and "Cylaplane FM DA-11" manufactured by JNC Corporation).

[0135] In a urethane resin having siloxane bonds, the content of the portion constituting the siloxane bonds is preferably 0.1 to 50% by mass, and more preferably 0.1 to 30% by mass, relative to the total mass of the urethane resin having siloxane bonds. The above content is set appropriately in consideration of the peelability of the peel surface and the ease of forming the peel layer.

[0136] The urethane resin can be manufactured by known methods using the above components. Known catalysts such as organometallic compounds and tertiary amine compounds can be used in the manufacture of the urethane resin. The release layer forming composition used in the manufacture of the release layer containing the urethane resin is preferably an aqueous dispersion of the urethane resin. The aqueous dispersion of the urethane resin is preferably further containing neutralizing agents such as amines and ammonia, as this improves the water dispersibility of the urethane resin.

[0137] The urethane resin contained in the release layer may or may not be crosslinked. Preferably, the urethane resin contained in the release layer is a crosslinked body formed by the reaction of a urethane resin C having a reactive group C and a crosslinking agent D having a reactive group D that can react with the reactive group C, in order to have superior release properties of the release surface.

[0138] The urethane resin C is a compound having a urethane bond in its main chain and a reactive group C. The reactive group C of the urethane resin C is, including in preferred embodiments, synonymous with the reactive group A of the acrylic resin A. The urethane resin C is -Si(R) ３ Preferably, it has at least one of the siloxane bond, and -Si(R) ３ It is more preferable to have both and siloxane bonds. The urethane resin C has -Si(R) ３ For specific examples and preferred embodiments of the siloxane bond, please refer to the -Si(R) bond present in the above-mentioned acrylic resin. ３ And it is similar to a siloxane bond.

[0139] The urethane resin C may contain only one type or two or more types. The content of urethane resin C is preferably 20 to 90% by mass, more preferably 30 to 80% by mass, and even more preferably 50 to 80% by mass, based on the total mass of the release layer. When the release layer contains a crosslinked product of urethane resin C and crosslinking agent D, it is preferable that the content of the structure derived from urethane resin C satisfies the above range.

[0140] The crosslinking agent D is a compound having a reactive group D that can react with the reactive group C of the urethane resin C. The crosslinking agent D is preferably water-soluble, as this facilitates the formation of a release layer by in-line coating. A crosslinked product of the urethane resin C and the crosslinking agent D can be formed, for example, by the reaction between the reactive group C of the urethane resin C and the reactive group D of the crosslinking agent D when forming a release layer using a composition containing the urethane resin C and the crosslinking agent D.

[0141] When the urethane resin C has a carboxyl group, a carboxylic acid anhydride group, or a carboxylic acid base, the reactive group D is preferably an oxazoline group, a carbodiimide group, an epoxy group, a methylol group, an isocyanate group, or a blocked isocyanate group, in terms of excellent reactivity with the carboxyl group, etc. Among these, the oxazoline group, epoxy group, or carbodiimide group is more preferred in terms of superior peelability of the peeled surface, the oxazoline group or epoxy group is even more preferred, and the oxazoline group is particularly preferred. When the urethane resin C has a hydroxyl group, the reactive group D is preferably an isocyanate group, a methylol group, or a blocked isocyanate group, in terms of excellent reactivity with the hydroxyl group.

[0142] The crosslinking agent D having the reactive group D is not particularly limited, and examples include one or more crosslinking agents selected from the group consisting of oxazoline compounds, isocyanate compounds, carbodiimide compounds, melamine compounds, and epoxy compounds. The isocyanate compound may be a compound having a blocked isocyanate group. Among these, oxazoline compounds, epoxy compounds, or carbodiimide compounds are preferred in terms of superior peelability of the peeled surface, oxazoline compounds or epoxy compounds are more preferred, and oxazoline compounds are even more preferred.

[0143] The release layer preferably contains a crosslinked product of a urethane resin C having siloxane bonds and a crosslinking agent D as the urethane resin. In particular, it is more preferable that the urethane resin C having siloxane bonds is in the above-mentioned preferred embodiment, and that at least one of the above-mentioned preferred embodiment is met, and it is even more preferable that the urethane resin C having siloxane bonds is in the above-mentioned preferred embodiment and the crosslinking agent D is in the above-mentioned preferred embodiment.

[0144] When the release layer contains a crosslinked urethane resin C and a crosslinking agent D, the content of the crosslinked urethane resin C and crosslinking agent D is preferably 98 to 100% by mass, and more preferably 98.5 to 100% by mass, relative to the total mass of the release layer, in terms of having superior release properties of the release surface.

[0145] (Silicone Resins) Silicone resins refer to resins that have a silicone structure (siloxane bond) in their molecules. However, acrylic resins and urethane resins that have siloxane bonds are not included in silicone resins. Examples of silicone resins include curable silicone resins, silicone graft resins, and modified silicone resins such as alkyl-modified silicone resins, with reactive curable silicone resins being preferred. Examples of reactive curable silicone resins include addition reaction silicone resins, condensation reaction silicone resins, and ultraviolet or electron beam curable silicone resins. Among these, addition reaction silicone resins with low-temperature curing properties, or ultraviolet or electron beam curable silicone resins are preferred because they can form a release layer at low temperatures.

[0146] Addition reaction-type silicone resins include, for example, resins obtained by reacting polydimethylsiloxane with vinyl groups introduced to the terminals or side chains with hydrodienesiloxane using a platinum catalyst and curing the reaction. Condensation reaction-type silicone resins include, for example, resins having a three-dimensional crosslinked structure formed by condensing polydimethylsiloxane having OH groups at the terminals with polydimethylsiloxane having H groups at the terminals using an organotin catalyst. UV-curing-type silicone resins include those that utilize the same radical reaction as silicone rubber crosslinking, those that are photocured by introducing unsaturated groups, those that decompose onium salts with ultraviolet light or electron beams to generate strong acids and cleave epoxy groups to crosslink, and those that are crosslinked by the addition reaction of thiols to vinylsiloxane. More specifically, examples include acrylate-modified polydimethylsiloxane and glycidoxy-modified polydimethylsiloxane.

[0147] The release layer offers superior release properties for the ceramic green sheet, and is made of -Si(R). ３ and an acrylic resin having at least one of the siloxane bonds, and -Si(R) ３Preferably, it contains at least one resin selected from the group consisting of urethane resins having at least one of a siloxane bond, and more preferably, it contains an acrylic resin having a siloxane bond, or a urethane resin having a siloxane bond, and -Si(R) ３ An acrylic resin having both the structure represented by and a siloxane bond, or -Si(R) ３ It is even more preferable to include a urethane resin having both the structure represented by and a siloxane bond.

[0148] The release layer may contain additives other than those listed above. Examples of additives include light and heavy release additives for adjusting the release force, surfactants, adhesion enhancers, conductive compounds, waxes, antioxidants, UV absorbers, colorants, strengthening agents, plasticizers, flame retardants, rust inhibitors, and mold inhibitors. Among these, it is preferable that the release layer contains a surfactant. Specific examples of surfactants are the same as those that may be included in the antistatic layer described above. When the release layer contains additives, the additive content is preferably 0.1 to 3% by mass, and more preferably 0.1 to 2% by mass, relative to the total mass of the release layer. It is preferable that the release layer does not contain conductive compounds in order to easily form a release layer surface with a maximum protrusion height Sp of less than 60 nm. Conductive compounds tend to form aggregates with other components, so when the release layer does not contain conductive compounds, the smoothness and release properties of the release layer surface are superior. On the other hand, it is preferable that the release layer contains conductive compounds in order to reduce the adhesion of foreign matter to the release layer surface by reducing the surface resistance value of the release layer surface.

[0149] The content of the release agent (more preferably the resin) in the release layer is preferably 50 to 99% by mass, and more preferably 60 to 98% by mass, based on the total mass of the release layer. The remainder of the release layer other than the resin may be the above-mentioned additives and / or residues of solvents and catalysts contained in the release layer forming composition used to form the release layer.

[0150] (Physical properties of the release layer) The thickness of the release layer can be set according to its intended use and is not particularly limited, but is preferably 0.005 to 2.0 μm, more preferably 0.005 to 1.0 μm, and even more preferably 0.005 to 0.5 μm. Furthermore, in terms of achieving a good balance between release performance and surface smoothness of the release layer, the thickness of the release layer is preferably 2 to 250 nm, more preferably 5 to 100 nm, and even more preferably 5 to 40 nm. The thickness of the release layer is measured in accordance with the method for measuring the thickness of the polyester substrate described above.

[0151] - Maximum protrusion height Sp and average surface roughness Sa In this film, the maximum protrusion height Sp on the surface of the release layer is less than 60 nm. In terms of making the release layer smoother, the maximum protrusion height Sp on the surface of the release layer is preferably 50 nm or less, more preferably 30 nm or less, even more preferably less than 20 nm, particularly preferably 14 nm or less, and most preferably less than 10 nm. The maximum protrusion height Sp on the surface of the release layer may be 1 nm or more, and is preferably 3 nm or more in terms of improving transportability and reducing winding failures. The average surface roughness Sa of the surface of the release layer is, for example, 0 to 5 nm, and is preferably 0 to 2 nm in terms of superior smoothness.

[0152] The maximum protrusion height Sp and average surface roughness Sa of the release layer surface can be adjusted by selecting the type of polyester and additives contained in the polyester substrate (for example, using polyester polymerized with titanium or aluminum compounds), and the type of release agent contained in the release layer.

[0153] - Silicon Atom Content The silicon atom content on the surface of the release layer is preferably 25 atm% or less, more preferably 20 atm% or less, even more preferably 15 atm% or less, particularly preferably 10 atm% or less, and most preferably 8 atm% or less, from the viewpoint of superior coating properties of the ceramic slurry and release properties of the ceramic green sheet formed on the surface of the release layer. Furthermore, the silicon atom content on the surface of the release layer is preferably 1 atm% or more, more preferably 2 atm% or more, and even more preferably 3 atm% or more, from the viewpoint of superior release properties of the ceramic green sheet formed on the surface of the release layer.

[0154] As mentioned above, this film has a surface resistance value of 1 × 10 １１ It is presumed that the increase in charge during the transport and delivery process is suppressed by having an antistatic layer with a charge ratio of less than Ω / □, the inclusion of particles in the antistatic layer, good slipperiness on the surface of the antistatic layer, and the maximum protrusion height Sp on the surface of the release layer being less than 60 nm. Furthermore, it is presumed that suppressing the increase in charge suppresses the phenomenon of the ceramic slurry being repelled by the surface of the release layer, thereby improving the coatability of the ceramic slurry onto the surface of the release layer. Moreover, it is presumed that if the silicon atom content on the surface of the release layer is below the above upper limit, the difference in triboelectric series between the antistatic layer and the release layer becomes smaller, reducing the charge on both the antistatic layer and the surface of the release layer, thus further improving the coatability of the ceramic slurry.

[0155] The silicon atom content on the surface of the release layer refers to the silicon atom content (atm%) relative to the total number of atoms of silicon, carbon, oxygen, nitrogen, and sulfur atoms, as measured by X-ray photoelectron spectroscopy (XPS). The silicon atom content on the surface of the release layer can be adjusted by the composition of the release layer (particularly the structure of the acrylic resin contained in the release layer) and the thickness of the release layer.

[0156] The silicon atom content described above can be measured using an XPS analyzer. More specifically, the content of the following five elements present on the outermost surface of the exfoliated layer is measured using an XPS analyzer under the following conditions, and the silicon atom content (atm%) is calculated when the total amount of atoms measured is set to 100 atm%. The arithmetic mean of the values ​​obtained by performing the above measurement three times is taken as the silicon atom content (atm%) on the surface of the exfoliated layer. (Measurement conditions) Analyst: X-ray photoelectron spectrometer, manufactured by Ulvac-PHI X-ray source: Monochromatic Al-Kα Measured elements: Carbon (C), Nitrogen (N), Oxygen (O), Silicon (Si), Sulfur (S) Measurement area: 300 μm × 300 μm Number of measurements: n = 3 Sputtering irradiation ions: Argon Energy: 94 eV (0.1 eV step)

[0157] • Surface free energy of the peeled layer surface is 60 mJ / m ２It is often less than 35 mJ / m ２ The following is preferable: 30 mJ / m ２ The following is more preferable: 28 mJ / m ２ The following is even more preferable: The surface free energy of the peeled layer surface is 15 mJ / m ２ The above is preferable, and 17 mJ / m ２ The above is more preferable: 20 mJ / m ２ The above is even more preferable. The surface free energy of the delamination layer surface can be adjusted, for example, by the silicon atom content of the delamination layer surface. The method for measuring the surface free energy of the delamination layer surface is as described in the Examples section below.

[0158] The method for forming the release layer is not particularly limited, but it is preferable that the release layer is formed by in-line coating. More specifically, it is preferable that the release layer is formed by curing a release layer-forming composition by in-line coating. The method for forming the release layer will be described in more detail later in the section on [Method for Manufacturing Polyester Film].

[0159] The film may have layers other than the antistatic layer, polyester substrate, and release layer. Examples of other layers include an intermediate layer disposed between the antistatic layer or release layer and the polyester substrate. Preferably, the film does not have the above-mentioned other layers, and the antistatic layer and the polyester substrate are in contact, and the polyester substrate and the release layer are in contact. That is, it is preferable that the film is a multilayer film consisting of an antistatic layer, a polyester substrate, and a release layer.

[0160] <Physical Properties of Polyester Film> Next, we will explain the physical properties of this film.

[0161] (Surface resistance value) The surface resistance value of the antistatic layer surface of this film is 1.0 × 10 １１ It is less than Ω / □. In this film, the surface resistance value of the antistatic layer surface is 5.0 × 10, which can further reduce deformation due to foreign matter adhesion. １０ A value less than Ω / □ is preferred, and 1.0 × 10 １０ A value less than Ω / □ is more preferable. The lower limit of the above surface resistivity is not particularly limited, for example, 1.0 × 10３ It may be Ω / □ or greater, and 1.0 × 10 ４ It may be Ω / □ or greater.

[0162] The surface resistance of the antistatic layer can be adjusted, for example, by the type and content of components (especially conductive compounds) contained in the antistatic layer. Specific measurement methods and conditions for the surface resistance of the antistatic layer are described in the examples below.

[0163] In this film, the maximum protrusion height Sp on both surfaces is preferably less than 60 nm, and more preferably 50 nm or less, in order to reduce deformation due to foreign matter adhesion and to further improve smoothness. The maximum protrusion height Sp on both surfaces is preferably 1 nm or more, and more preferably 3 nm or more, in order to improve transportability.

[0164] In this film, the maximum protrusion height Sp of one surface and the maximum protrusion height Sp of the other surface may be the same or different, but it is preferable that they be different. In particular, it is preferable that the maximum protrusion height Sp of the smooth surface is greater than the maximum protrusion height Sp of the peel surface. This further reduces deformation due to foreign matter adhesion, improves the transportability of the polyester film, and reduces winding failures.

[0165] The thickness of this film is preferably 200 μm or less, more preferably 100 μm or less, even more preferably 40 μm or less, and particularly preferably 35 μm or less, in terms of cost-effectiveness. There is no particular lower limit to the thickness, but in terms of improved strength and processability, it is preferably 1 μm or more, more preferably 3 μm or more, even more preferably 10 μm or more, and particularly preferably 18 μm or more. The thickness of this film is determined by measuring the thickness at five arbitrarily selected different locations using a stylus-type film thickness gauge and taking the arithmetic mean of the obtained measurements.

[0166] [Method for Manufacturing Polyester Film] The method for manufacturing the film is not particularly limited as long as it can produce a polyester film having the above configuration. For example, one method is to produce an unstretched polyester substrate by melt extrusion of polyester, then stretch the unstretched polyester substrate longitudinally, apply an antistatic layer-forming composition to one side of the uniaxially stretched polyester substrate, apply a release layer-forming composition to the other side of the polyester substrate, and then stretch the resulting double-sided coated polyester substrate transversely to produce the film. In other words, one method is to have a longitudinal stretching step of stretching an unstretched polyester substrate longitudinally, an antistatic layer-forming step of forming an antistatic layer, a release layer-forming step of forming a release layer, and a transverse stretching step of stretching the polyester substrate transversely.

[0167] Longitudinal stretching can be performed, for example, by conveying an unstretched polyester substrate in the longitudinal direction while applying tension between two or more stretching rolls installed in the conveying direction. The stretching ratio in the longitudinal stretching process is set appropriately depending on the application, but is preferably 2.0 to 5.0 times, more preferably 2.5 to 4.0 times, and even more preferably 2.8 to 4.0 times.

[0168] The composition for forming the antistatic layer is not particularly limited as long as it is a composition capable of forming the antistatic layer described above. Examples of compositions for forming the antistatic layer include compositions containing particles, conductive compounds, and binders included in the antistatic layer. The composition for forming the antistatic layer may also contain a crosslinking agent. Known crosslinking agents can be used as the crosslinking agent. The composition for forming the antistatic layer may also contain a solvent. Examples of solvents include water and organic solvents such as ethanol.

[0169] The method for applying the antistatic layer-forming composition is not particularly limited, and known methods can be used. Examples of application methods include spray coating, slit coating, roll coating, blade coating, spin coating, bar coating, and dip coating. As an application method, it is preferable to apply an in-line coating method in which the antistatic layer-forming composition is applied to one surface of a longitudinally stretched polyester substrate while the longitudinally stretched polyester substrate is being conveyed. As an application method, an offline coating method may be applied in which the antistatic layer-forming composition is applied to one surface of a biaxially stretched polyester substrate.

[0170] The composition for forming the release layer is not particularly limited as long as it is a composition that can form the release layer described above. Examples of compositions for forming the release layer include compositions containing the release agent described above. The composition for forming the release layer may also contain a solvent.

[0171] Methods for applying the release layer-forming composition are the same as those for applying the antistatic layer-forming composition. Preferably, an in-line coating method is applied, in which the release layer-forming composition is applied to one surface of the longitudinally stretched polyester substrate while the longitudinally stretched polyester substrate is being transported. Alternatively, an off-line coating method may be applied, in which the release layer-forming composition is applied to the surface of the biaxially stretched polyester substrate opposite to the antistatic layer.

[0172] Transverse stretching is a process of stretching a longitudinally stretched polyester substrate in the width direction.

[0173] The above manufacturing method may include other steps in addition to the longitudinal stretching step, the layering step, and the transverse stretching step. For example, the manufacturing method according to this embodiment may include at least one step selected from the group consisting of a heat setting step of heating and heat fixing a biaxially stretched polyester substrate, a heat relaxation step of heating the polyester substrate heat-fixed in the heat setting step at a lower temperature than the heat setting step to relax it, a cooling step of cooling the polyester substrate that has been relaxed in the heat relaxation step, and an expansion step of expanding the polyester substrate that has been relaxed in the cooling step in the width direction. Specifically, the conditions described in paragraphs

[0085] to

[0165] of International Publication No. 2023 / 281972 are preferred.

[0174] In the above-described method for manufacturing the film, an antistatic layer is formed by applying an antistatic layer-forming composition in the antistatic layer formation step. However, the method for forming the antistatic layer is not limited to the above embodiment, and known methods can be applied. For example, one method is to form an unstretched polyester substrate with a laminated antistatic layer by co-extrusion molding.

[0175] [Applications] This film can be applied to a variety of uses. For example, this film is preferably used as a release film (carrier film) for the manufacture of ceramic green sheets. Ceramic green sheets manufactured using this film can be suitably used in the manufacture of ceramic capacitors, where multilayering of internal electrodes is required due to miniaturization and increased capacitance. In particular, this film exhibits less deformation due to foreign matter adhesion and superior smoothness of the release surface. Therefore, when manufacturing ceramic green sheets using this film, variations in the thickness of the ceramic green sheet caused by deformation can be suppressed, and the performance of the multilayer ceramic capacitor manufactured using that ceramic green sheet can be improved.

[0176] The method for producing a ceramic green sheet using this film is not particularly limited and can be carried out by known methods. For example, a method for producing a ceramic green sheet involves applying a prepared ceramic slurry to the release surface of the film and drying off the solvent contained in the ceramic slurry. The method for applying the ceramic slurry is not particularly limited; for example, a known method such as applying a ceramic slurry, which is a dispersion of ceramic powder and a binder agent in a solvent, by a reverse roll method and removing the solvent by heating and drying can be applied. The binder agent is not particularly limited; for example, polyvinyl butyral can be used. The solvent is also not particularly limited; for example, ethanol and toluene can be used.

[0177] The fabricated ceramic green sheet is used to manufacture ceramic capacitors. Known methods can be applied to manufacture ceramic capacitors using ceramic green sheets, for example, the following method. First, internal electrodes are provided on a laminate of the main film and the ceramic green sheet by applying or printing a conductive paste. Next, the main film is removed from the laminate, and ceramic green sheets with internal electrodes are sequentially laminated, and the resulting laminate is pressed to produce an intermediate laminate. After cutting the intermediate laminate into a desired shape, the cut intermediate laminate is fired to obtain a ceramic body. Next, external electrodes that electrically connect to the internal electrodes are formed on the two end faces of the fired intermediate laminate using a conductive paste such as silver, thereby obtaining a ceramic capacitor.

[0178] This film can be used as a protective film for dry film resists, a decorative layer and a film for sheet molding such as resin sheets, a release film for process manufacturing such as semiconductor manufacturing processes, polarizing plate manufacturing processes and battery manufacturing processes, and as a separator for adhesive films such as labels, medical and office supplies.

[0179] The present invention will be described in more detail below based on examples. The materials, amounts used, proportions, processing content, and processing procedures shown in the following examples can be modified as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be interpreted as being limited by the examples shown below. Unless otherwise specified, "parts" and "%" are based on mass.

[0180] [Example 1] An unstretched polyester substrate was prepared with reference to the conditions described in paragraphs

[0160] to

[0169] of International Publication No. 2020 / 158316. The obtained unstretched polyester substrate was longitudinally stretched. The antistatic layer-forming composition B1 described below was applied to one side of the longitudinally stretched polyester substrate, and the release layer-forming composition L2 described below was applied to the opposite side. The respective coated films were dried with hot air at 100°C to form an antistatic layer and a release layer. That is, the antistatic layer-forming composition B1 and the release layer-forming composition L2 were applied in-line. At this time, the amount of coating was adjusted so that the thickness of the antistatic layer was 40 nm and the thickness of the release layer was 15 nm in the prepared biaxially oriented polyester film.

[0181] When preparing each composition, after mixing the components, filtration and membrane degassing (2x6 radial flow superphobic, manufactured by Polypore Co., Ltd.) were performed. When preparing composition L2 for forming the peeling layer, the above filtration treatment was performed using a depth-pleated type filter (SHPH010, manufactured by Rokitechno Co., Ltd.) with a pore size of 1 μm. When preparing composition B1 for forming the antistatic layer, the above filtration treatment was performed by connecting a filter (F20, manufactured by MAHLE Filter Systems Co., Ltd.) with a pore size of 6 μm and a depth-pleated type filter (SHPH010, manufactured by Rokitechno Co., Ltd.) with a pore size of 1 μm in series.

[0182] The obtained film with the coating film was stretched horizontally to produce a biaxially stretched polyester film with a width of 1500 mm, wound up every 7000 m without nailing, and a roll-shaped polyester film was obtained. The thickness of the produced biaxially stretched polyester film (the polyester film of Example 1) was 30 μm. The intrinsic viscosity of the biaxially stretched polyester film (the polyester film of Example 1) was 0.63 dl / g. In the polyester film, the polyester base material substantially does not contain particles, and with respect to the total mass of the polyester film, the Sb content is 0 to 1 mass ppm, the Ti content is 7 ppm, the Mg content is 75 ppm, and the P content is 65 ppm. Table 1 shows the results of measuring the physical properties of the release surface and the antistatic layer surface.

[0183] <Release layer forming composition L2>The following components were mixed to obtain a release layer forming composition L2. ・Acrylic resin A1 (containing structural units derived from SiMA-1 (described later) / structural units derived from methacrylic acid (MAA) / structural units derived from hydroxyethyl methacrylate (HEMA) in a mass ratio of 70 / 20 / 10. Solid content concentration: 20% by mass): 82.5 parts by mass (16.5 parts by mass as solid content) ・Crosslinking agent X2 (a oxazoline compound composed of an acrylic resin containing structural units derived from 2-isopropenyl-2-oxazoline / structural units derived from methoxypolyethylene glycol acrylate / structural units derived from ethyl acrylate / structural units derived from methyl methacrylate in a mol ratio of 48 / 10 / 2 / 40, having no acid groups. Weight average molecular weight Mw: 23000. Oxazoline value = 4.8. Solid content concentration: 25% by mass): 44 parts by mass (11 parts by mass as solid content) ・Water: 873.5 parts by mass

[0184] Acrylic resin A1 was synthesized by the following method. A 1-liter three-necked flask equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas inlet tube was charged with 1-propanol (92.83 g) and heated to 80°C under a nitrogen stream. Here, a mixed solution 1 obtained by mixing 2.16 g of V-601 (radical polymerization initiator; manufactured by Fuji Film Wako Pure Chemical Corporation) and 30.94 g of 1-propanol, 20.00 g of methacrylic acid (MAA), and methacrylic-modified silicone oil (CH ２ =C(CH３ )-(C(O)O)-L １１ -[Si(CH ３ ) ２ -O] ｍ -SiR(CH ３ ) ２ . In the formula, the definition of L １１ is the same as the definition of L in the above formula (A1-1), and the definitions of m and R in the formula are the same as the definitions of m and R in the group represented by the above-[Si(R) １１ -O] ２ -Si(R) ｍ . Molecular weight: about 1000. Denoted as "SiMA-1"). 70.00 g, 10.00 g of hydroxyethyl methacrylate (HEMA), 0.66 g of dodecyl mercaptan, and 30.94 g of 1-propanol were mixed to obtain a mixed solution 2, which was dropped at a constant speed under the dropping conditions where the dropping was completed in 3 hours each. After the dropping of the mixed solution was completed, a mixed solution of 0.32 g of V-601 and 2 g of 1-propanol was added to the obtained reaction mixture, and the mixture was heated and stirred for 6 hours. After adding 49.39 g of ethanol to the obtained reaction mixture, 16.57 g of dimethylaminoethanol (neutralizing agent) (DMAE) was dropped with a dropping funnel, and water was added to adjust the solid content concentration to 20% to obtain a solution of acrylic resin A1.

[0185] <Antistatic layer forming composition B1> The following components were mixed to obtain an antistatic layer forming composition B1. - Composition Y1 ("Orgacon (trademark) ASI-210", manufactured by Nippon Agfa Materials Co., Ltd., a composition containing PEDOT / PSS, solid content concentration 13% by mass): 191.4 parts by mass - Particles P1 ("Snowtex (registered trademark) ZL", manufactured by Nissan Chemical Industries, Ltd., colloidal silica, average particle diameter 85 nm, solid content concentration 40% by mass aqueous dispersion): 10.3 parts by mass - Distilled water: 798.3 parts by mass

[0186] [Example 2] The following components were mixed to obtain an antistatic layer forming composition B2. A biaxially stretched polyester film was produced in the same manner as in Example 1, except that the antistatic layer forming composition B2 was used instead of the antistatic layer forming composition B1 and the thickness of the antistatic layer was changed to the thickness shown in Table 1.

[0187] ​​<Composition B2 for forming an antistatic layer> ・Composition Y1 (solid content concentration 13% by mass): 191.4 parts by mass ・Crossing agent X1 ("Epocross WS-700", an acrylic resin containing constituent units derived from oxazoline compounds and without acid groups, manufactured by Nippon Shokubai Co., Ltd., solid content concentration 25% by mass): 40 parts by mass ・Particles P1 (solid content concentration 40% by mass): 10.3 parts by mass ・Anionic hydrocarbon surfactant S1 ("Rapizol (registered trademark) A-90", manufactured by NOF Corporation, sodium di-2-ethylhexyl sulfosuccinate) diluted with 1% by mass of solid content in water: 55.7 parts by mass ・Acetylene surfactant S2 ("Surfinol (registered trademark) 440", manufactured by Nisshin Chemical Industry Co., Ltd., solid content concentration 100% by mass): 0.5 parts by mass ・Distilled water: 702.2 parts by mass

[0188] [Example 3] Composition B3 for forming an antistatic layer is obtained by mixing the components shown below. A biaxially oriented polyester film is prepared in the same manner as in Example 1, except that composition B3 for forming an antistatic layer is used instead of composition B1 for forming an antistatic layer, and the thickness of the antistatic layer is changed to the thickness shown in Table 1.

[0189] <Composition B3 for forming an antistatic layer> • Composition Y1 (solid content concentration 13% by mass): 191.4 parts by mass • Crosslinking agent X1 (solid content concentration 25% by mass): 30 parts by mass • Particles P1 (Snowtex ZL, solid content concentration 40% by mass): 10.3 parts by mass • Anionic hydrocarbon surfactant S1 (1% by mass water dilution): 55.7 parts by mass • Acetylene surfactant S2 (solid content concentration 100% by mass): 0.5 parts by mass • Distilled water: 712.2 parts by mass

[0190] [Example 4] Composition B4 for forming an antistatic layer is obtained by mixing the components shown below. A biaxially oriented polyester film is prepared in the same manner as in Example 1, except that composition B4 for forming an antistatic layer is used instead of composition B1 for forming an antistatic layer, and the thickness of the antistatic layer is changed to the thickness shown in Table 1.

[0191] <Composition B4 for forming an antistatic layer> • Composition Y1 (solid content concentration 13% by mass): 191.4 parts by mass • Crosslinking agent X1 (solid content concentration 25% by mass): 50 parts by mass • Particles P1 (solid content concentration 40% by mass): 10.3 parts by mass • Anionic hydrocarbon surfactant S1 (solid content concentration 1% by mass diluted with water): 55.7 parts by mass • Acetylene surfactant S2 (solid content concentration 100% by mass): 0.5 parts by mass • Distilled water: 692.2 parts by mass

[0192] [Example 5] Composition B5 for forming an antistatic layer was obtained by mixing the components shown below. A biaxially oriented polyester film was prepared in the same manner as in Example 1, except that composition B5 for forming an antistatic layer was used instead of composition B1 for forming an antistatic layer, and the thickness of the antistatic layer was changed to the thickness shown in Table 1.

[0193] <Composition B5 for forming an antistatic layer> ・Composition Y1 (solid content concentration 13% by mass): 191.4 parts by mass ・Polyester PE1 ("Pluscoat Z880", manufactured by Go-o Chemical Industry Co., Ltd., contains sulfonic acid group, acid value 5 mg KOH / g or less, solid content concentration 25% by mass): 40 parts by mass ・Particle P1 (solid content concentration 40% by mass): 10.3 parts by mass ・Anionic hydrocarbon surfactant S1 (water dilution solution with solid content concentration 1% by mass): 55.7 parts by mass ・Acetylene surfactant S2 (solid content concentration 100% by mass): 0.5 parts by mass ・Distilled water: 702.2 parts by mass

[0194] [Example 6] By mixing the components shown below, a release layer-forming composition L1 is obtained. A biaxially oriented polyester film is prepared in the same manner as in Example 5, except that release layer-forming composition L1 is used instead of release layer-forming composition L2.

[0195] <Composition L1 for forming a release layer> ・Silicone emulsion (DEHESIVE EM480, manufactured by Asahi Kasei Wacker Silicone Co., Ltd.): 200 parts by mass ・Silicone emulsion (CROSSLINKER V72, manufactured by Asahi Kasei Wacker Silicone Co., Ltd.): 30 parts by mass ・Silane coupling agent (KBM403, manufactured by Shin-Etsu Chemical Co., Ltd.): 1 part by mass ・Water: 770 parts by mass

[0196] [Example 7] Acrylic resin A2 was synthesized by adjusting the amount of each monomer added in the synthesis of acrylic resin to contain SiMA-1 derived constituent units, MAA derived constituent units, and HEMA derived constituent units in a mass ratio of 50 / 20 / 30. The obtained acrylic resin A2 was used in place of acrylic resin A1 to prepare a release layer forming composition L3. Next, a biaxially oriented polyester film was prepared in the same manner as in Example 5, except that release layer forming composition L3 was used in place of release layer forming composition L2.

[0197] [Example 8] Acrylic resin A3 was synthesized by adjusting the amount of each monomer added in the synthesis of the acrylic resin to contain SiMA-1 derived constituent units, MAA derived constituent units, and HEMA derived constituent units in a mass ratio of 30 / 40 / 30. The obtained acrylic resin A3 was used in place of acrylic resin A1 to prepare a release layer forming composition L4. Next, a biaxially oriented polyester film was prepared in the same manner as in Example 5, except that release layer forming composition L4 was used in place of release layer forming composition L2.

[0198] [Example 9] 10.00 parts of hydroxyl-modified silicone (FM DA-11, manufactured by JNC Corporation), 50.87 parts of polycarbonate diol (Duranole T5651, manufactured by Asahi Kasei Corporation), 9.25 parts of dimethylolpropionic acid, 66.66 parts of methyl ethyl ketone, and 29.88 parts of isophorone diisocyanate were charged into a flask. The resulting mixture was heated to 70°C, and 0.16 parts of inorganic bismuth catalyst (Neostan U-600, manufactured by Nitto Kasei Co., Ltd.) were added to the mixture and the mixture was reacted for 7 hours. 100.00 parts of methyl ethyl ketone and 70.00 parts of 2-propanol were added to the reaction solution and stirred at 70°C for a further 3 hours to obtain solution U1 (30% solids) containing a urethane resin having siloxane bonds. 0.65 parts of dimethylethanolamine were added to 83.22 parts of the obtained solution U1, and a neutralization reaction was carried out. 74.84 parts of water were added to the mixture after the reaction, and the oil phase component and the aqueous phase component were mixed. The obtained mixture was emulsified by stirring at 7000 rpm for 30 minutes using a homogenizer at room temperature (25°C) to obtain an emulsion. Distilled water (26.82 g) was added to the obtained emulsion, and the resulting liquid was heated to 50°C, and the organic solvent was removed from the liquid while stirring at 50°C for 4 hours. The liquid from which the organic solvent had been removed was diluted with distilled water to a solid content of 25% by mass to obtain a release layer forming composition L5 containing a urethane resin having siloxane bonds. Next, a biaxially oriented polyester film was prepared in the same manner as in Example 5, except that release layer forming composition L5 was used instead of release layer forming composition L2.

[0199] [Example 10] Acrylic resin A4 was synthesized by adjusting the amount of each monomer added in the synthesis of acrylic resin to contain constituent units derived from SiMA-1, MAA, and HEMA in a mass ratio of 80 / 10 / 10. The obtained acrylic resin A4 was used in place of acrylic resin A1 to prepare a release layer forming composition L6. Next, a biaxially oriented polyester film was prepared in the same manner as in Example 5, except that release layer forming composition L6 was used in place of release layer forming composition L2.

[0200] [Example 11] In the preparation of the release layer forming composition L6, the amount of acrylic resin A4 added was changed to 123 parts by mass (24.6 parts by mass in solid content), and the amount of crosslinking agent X2 was changed to 10.5 parts by mass (2.625 parts by mass in solid content) to prepare the release layer forming composition L7. A biaxially oriented polyester film was then prepared in the same manner as in Example 10, except that the obtained release layer forming composition L7 was used in place of the release layer forming composition L6.

[0201] [Example 12] Composition B7 for forming an antistatic layer was obtained by mixing the components shown below. A biaxially oriented polyester film was prepared in the same manner as in Example 1, except that composition B7 for forming an antistatic layer was used instead of composition B1 for forming an antistatic layer, and the thickness of the antistatic layer was changed to the thickness shown in Table 1.

[0202] (Antistatic layer forming composition B7) After mixing the components shown below, the above-described filtration treatment and membrane degassing were performed to obtain antistatic layer forming composition B7. - Binder PU1 (35% by mass aqueous solution of Hydran AP-40N (manufactured by DIC Corporation)): 88.8 parts by mass - Anionic hydrocarbon surfactant S1 ("Rapizol® A-90", manufactured by NOF Corporation) 1% by mass aqueous dilution: 55.7 parts by mass - Particle P1 ("Snowtex® ZL", manufactured by Nissan Chemical Corporation, colloidal silica) 40.5% by mass aqueous dispersion: 10.3 parts by mass - Composition Y2 (CA652, poly(3,4-ethylenedioxythiophene) (PEDOT / PSS) doped with polystyrene sulfonate, a polythiophene-based conductive polymer, as the conductive polymer, manufactured by Chukyo Oil & Fats Co., Ltd.) 1.45% by mass aqueous dispersion: 52.5 parts by mass - Conductive additive (sorbitol) 100% by mass solids: 4.6 parts by mass - Distilled water: 787.7 parts by mass

[0203] [Comparative Example 1] A biaxially oriented polyester film is prepared by referring to paragraphs

[0170] to

[0179] of International Publication No. 2023 / 281972, except that composition A1 is used instead of composition B1 for forming the antistatic layer, and the thickness of the formed particle-containing layer is changed to the thickness shown in Table 1. Composition A1 is obtained by mixing the components shown below, similar to composition B1 for forming the antistatic layer, and then subjecting it to the above-described filtration treatment and membrane degassing.

[0204] <Composition A1> - Olefin resin O1 ("Zyxene NC", manufactured by Sumitomo Seika Co., Ltd., acid-modified polyolefin, diluted with water to a solid content concentration of 25% by mass): 157 parts by mass - Anionic hydrocarbon surfactant S1 (water-diluted solution with a solid content concentration of 1% by mass): 56 parts by mass - Particles P1 (water-dispersed solution with a solid content concentration of 40% by mass): 11 parts by mass - Water: 776 parts by mass

[0205] [Physical Property Measurement] <Elastic Modulus of the Antistatic Layer> The polyester film obtained in Example 1 was cut to a size of 10 mm x 10 mm. Next, the release layer side of the cut polyester film and the glass plate were bonded and fixed with epoxy adhesive to obtain a test specimen. Measurements were taken in the region of the antistatic layer of the test specimen where no particles were present, using the peak force tapping mode of an AFM (Burker, DimensionIcon), to obtain a force curve, and the indentation modulus was determined. The specific procedure is shown below. First, preliminary measurements were performed to calibrate the cantilever and probe. The cantilever's warp sensitivity was calculated from the slope of the force curve of the quartz substrate. The cantilever's warp sensitivity was 75.57 nm / V. The spring constant was calculated by measuring the thermal fluctuation of the probe. Specifically, it was calculated using the Thermal Tune method included in the software of the Burker AFM. The spring constant was 12.88 N / m. The tip curvature of the probe was calculated by measuring the shape of a tip curvature calibration sample (RM-12M: Ti Roughness Sample) and using the image analysis mode (Tip Qualification) included with the software for Bruker AFM. The tip curvature of the probe was 10.4 nm. Next, the surface shape of the test specimen was obtained by scanning a 3 μm × 3 μm area with a maximum indentation load of 25 nN. Referring to the obtained surface shape, a force curve was obtained by setting the maximum indentation load to 180 nN at one point in the region of the antistatic layer surface (smooth surface) where no particles were present. The elastic modulus was determined using the Hertz contact theory from the slope of the return force curve (in the region of 20-90% of the maximum load). The elastic modulus in the resin layer region was measured until there were five points within the same scanning area. Subsequently, the scanning area was changed, and the elastic modulus was obtained using the same procedure. Measurements were taken in five scanning areas for each test specimen, and the arithmetic mean of the values ​​obtained from a total of 25 elastic modulus measurements was taken to determine the indentation elastic modulus of the antistatic layer. Details of the measurement conditions are shown below.Cantilever: Bruker RTESPA-300 (Manufacturer's catalog specifications: Material: Si, Spring constant K: 40 (N / m), Resonant frequency f: 300 (kHz), Tip curvature R: 8 (nm)) Measurement atmosphere: 23℃, in air Resolution: 256 × 256 Scan Rate: 1.5 Hz.

[0206] <Surface Free Energy> For the polyester film obtained in Example 1, the surface free energy of the release layer surface was measured by the following method. Using a contact angle meter (Kyowa Interface Chemical Co., Ltd., DROPMASTER-501), droplets were dropped onto the release layer surface of the polyester film at 25°C, and the contact angle was measured 1 second after the droplet adhered to the release layer surface. As droplets, 2 μL of purified water, 1 μL of methylene iodide, and 1 μL of ethylene glycol were used, and the surface free energy was determined from the measured contact angles using the Kitazaki-Hata method.

[0207] <Maximum protrusion height Sp, average surface roughness Sa> The maximum protrusion height Sp and average surface roughness Sa were measured on both surfaces of the polyester film obtained in Example 1 using the following method. Both surfaces of the biaxially oriented polyester film were measured using an optical interferometer (Vertscan 3300G Lite, manufactured by Hitachi High-Tech Corporation) under the following conditions, and then analyzed using the built-in data analysis software (VS-Measure 5) to determine the maximum protrusion height Sp and average surface roughness Sa of the release layer surface and the antistatic layer surface. For the measurement of the maximum protrusion height Sp, the maximum value obtained from five measurements taken at different measurement positions was adopted, and for the measurement of the average surface roughness Sa, the average value obtained from five measurements taken at different measurement positions was adopted. (Measurement conditions) ・Measurement mode: WAVE mode ・Objective lens: 50x ・Measurement area: 186 μm × 155 μm

[0208] <Surface Resistance> The surface resistance of the antistatic layer surface of the polyester film was measured by the following method. The polyester film obtained in Example 1 was conditioned for 24 hours under conditions of 23°C and 65% humidity. A voltage of 100V was applied using a digital electrometer (8252, manufactured by ADCMT) and a resistance chamber (12704A, manufactured by ADCMT). The surface resistance was calculated from the current value measured 60 seconds after the start of voltage application.

[0209] <Silicon Atom Content> For the polyester film of Example 1, the silicon atom content (atm%) on the surface of the release layer was calculated using the method described above with an analytical instrument (X-ray photoelectron spectroscopy analyzer, manufactured by Ulvac-PHI) that uses XPS (X-ray photoelectron spectroscopy) as its measurement principle. If the silicon atom content is below the detection limit, it is indicated as "0" in the table.

[0210] [Evaluation] <Roller Charge Amount> A sample for measuring the roller charge amount was prepared by cutting the polyester film obtained in Example 1 to a size of 35 mm x 120 mm. Separately from the sample, a polyester film obtained in Example 1 was prepared and attached to the surface of a rubber roll so that the release layer was in contact with the rubber roll to create a transport roll A. The antistatic layer of the polyester film obtained in Example 1 was exposed on the surface of transport roll A. A transport roll B with a grounded metal surface was also prepared. Under conditions of 25°C and 60% humidity, the sample was placed between transport roll A and transport roll B so that the release layer of the sample was in contact with transport roll A and the antistatic layer of the sample was in contact with transport roll B, and the sample was transported using a nip transport method. The nip transported sample was placed in a Faraday cage and the amount of charge (unit: picocoulons (pC)) charged on the sample was measured.

[0211] <Deformation due to foreign matter> The 1500 mm wide, 7000 m long roll of polyester film obtained in Example 1 was fed at a speed of 60 m / min and a tension of 7.5 kg / m, and the central part was slit to a width of 0.9 m. The slit polyester film was wound onto a 3-inch diameter acrylonitrile-butadiene-styrene rubber core to obtain a 6000 m long slit roll. While winding the polyester film, a contact roll was pressed against the core via the polyester film, while adjusting the pressure so that it changed continuously from 20 kg / m at the start of winding to 35 kg / m at the end of winding. After one day had passed since preparation, a 1 m long film sample was taken from the surface of the slit roll, and the number of locations where minute deformation was observed in the film sample was counted by visual inspection. Furthermore, the slit roll was peeled back several times, and the presence or absence of foreign matter was visually checked at the locations corresponding to the areas where minute deformation was observed inside the roll. In the film samples, minute deformations were observed, and areas where foreign matter was found inside the roll were identified as areas where deformation occurred due to foreign matter, and the number of such deformations was measured.

[0212] Based on the number of deformations caused by foreign matter measured, the deformation due to foreign matter was evaluated according to the following evaluation criteria. The fewer the number of deformations caused by foreign matter, the better the polyester film is evaluated to maintain smoothness when applied as a release film in the manufacture of ceramic green sheets. (Evaluation Criteria) A: Number of deformations caused by foreign matter is 1 / m ２ Below, B: Number of deformations due to foreign matter: 1 / m ２ Super, 5 pieces / m ２ Below, C: Number of deformations due to foreign matter: 5 per meter ２ super

[0213] <Charging during feeding> A slit roll was manufactured according to the method for manufacturing a slit roll used in the evaluation of deformation due to foreign matter adhesion. The obtained slit roll was installed in a feeding device, and polyester film was fed at a speed of 100 m / min and a tension of 7.5 kg / m. Before contact with the first conveyor roller after feeding, the electrostatic potential (unit: kV) of the fed polyester film was measured using a electrostatic meter (SK-050, manufactured by Keyence Corporation). The average value of the measurements taken up to 1 minute after feeding at the above speed and tension was calculated and used as the electrostatic potential.

[0214] <Preparation and Evaluation of Ceramic Green Sheets> (Preparation of Ceramic Slurry) Barium titanate powder (BaTiO) ３ A mixture was prepared by mixing 100 parts by mass of (product name "BT-03" manufactured by Sakai Chemical Industry Co., Ltd.), 8 parts by mass of polyvinyl butyral resin (product name "Eslec® B・K BM-2" manufactured by Sekisui Chemical Co., Ltd.) as a binder, 4 parts by mass of dioctyl phthalate (product name "Kanto Chemical Co., Ltd." dioctyl phthalate, Grade 1) as a plasticizer, and 135 parts by mass of a mixture of toluene and ethanol (mass ratio 5:5). Zirconia beads were added to the above mixture and dispersed in the barium titanate powder mixture using a ball mill to obtain a dispersion. The zirconia beads were removed from the obtained dispersion to obtain a ceramic slurry. The ceramic slurry is a composition containing an organic solvent.

[0215] (Coatingability of ceramic slurry) A ceramic slurry was applied to the surface of the release layer of a polyester film using an applicator so that the thickness of the ceramic green sheet after drying was 0.2 μm, and the ceramic green sheet was formed on the surface of the release layer of the polyester film by drying at 80°C for 1 minute. The condition of the edges of the ceramic green sheet was observed using an optical microscope, and the coatingability of the ceramic slurry was evaluated based on the observed condition of the edges according to the following criteria. The lower the coatingability of the ceramic slurry, the more the applied ceramic slurry is repelled from the surface of the release layer of the polyester film, the more the ceramic slurry overflows at the edges of the ceramic slurry coating, and the greater the unevenness at the edges of the ceramic green sheet. - Coatingability Evaluation Criteria - A: No unevenness is observed at the edges of the ceramic green sheet. B: Slight unevenness is observed at the edges of the ceramic green sheet. C: Clear unevenness is observed at the edges of the ceramic green sheet.

[0216] (Peel strength of ceramic green sheet) A ceramic slurry was applied to the surface of the release layer of a polyester film using an applicator so that the thickness of the ceramic green sheet after drying was 0.2 μm, and the ceramic green sheet was formed on the surface of the release layer of the polyester film by drying at 90°C for 1 minute. Using a peel test machine (VPA-2S, manufactured by Kyowa Interface Chemical Co., Ltd., load cell load 1N), the ceramic green sheet formed on the surface of the release layer was peeled off at a peel angle of 90 degrees, a peel temperature of 25°C, and a peel speed of 0.3 m / min. For peeling, double-sided adhesive tape (No. 535A, manufactured by Nitto Denko Corporation) was attached to a SUS (stainless steel) plate attached to the peel test machine, and the polyester film with the ceramic green sheet attached was fixed on top of it with the ceramic green sheet side adhering to the double-sided tape, and peeled off by pulling the polyester film side. From the obtained measured values, the average value of the peel force for peel distances of 20 to 50 mm was calculated, and this value was defined as the peel force. Five measurements were taken, and the average of these peeling forces was used as the peel strength of the ceramic green sheet. A lower peel strength indicates better peelability of the peeling layer surface.

[0217] The polyester films of Examples 2, 5, and 7-11 were subjected to the same physical property measurements and evaluations as in Example 1, and the results shown in Table 1 were obtained. Similarly, the results obtained for the polyester films of Examples 3, 4, and 6 and Comparative Example 1 are shown in the table below.

[0218] In the table, under the "Release Layer" column, the "Composition Number" column indicates the number of the composition for forming the release layer, and the "Sp [nm]" column indicates the "Surface E [mJ / m]" column. ２ The "Surface Si Ratio [atm%]" column and the "Antistatic Layer (Particle-Containing Layer)" column indicate the maximum protrusion height Sp, surface free energy, and silicon atom content of the peeled surface, respectively. In the "Antistatic Layer (Particle-Containing Layer)" column, the "Composition Number" column indicates the number of the composition used to form the antistatic layer or particle-containing layer, and the "Conductive Compound," "Binder," "Surfactant," and "Particles" columns indicate the above components contained in each composition. The number in parentheses in the "Binder" column indicates the percentage (mass%) of resin or crosslinking agent content relative to the total solids content of each composition. In the "Antistatic Layer (Particle-Containing Layer)" column, the "AFM Modulus [GPa]," "Sa [nm]," and "Sp [nm]" columns indicate the modulus, average surface roughness Sa, and maximum protrusion height Sp of the surface of the antistatic layer or particle-containing layer, measured using AFM, respectively. Taking Example 1 as an example, the value "1.0 × 10^7" listed in the "Surface Resistance (Ω / □)" column of "Physical Properties" means that the surface resistance of the antistatic layer surface is 1.0 × 10^7. ７ This means that the ratio was Ω / □. Furthermore, the average surface roughness Sa of the peel surface of the polyester film in all examples was in the range of 0 to 2 nm.

[0219]

[0220]

[0221] As shown in Table 1, the polyester film of the present invention is evaluated as being applicable as a release film that exhibits little deformation due to foreign matter adhesion and can maintain surface smoothness when applied to the manufacture of ceramic green sheets. On the other hand, the surface resistance value of the antistatic layer surface is 1.0 × 10⁻⁶. １１In Comparative Example 1, the polyester film, with a charge ratio of Ω / □ or higher, exhibits high roller charge and feed charge, resulting in significant deformation due to foreign matter adhesion. Therefore, it is presumed that its smoothness will be inferior when applied to the manufacture of ceramic green sheets.

[0222] Furthermore, a comparison of Examples 1, 2, and 5 confirmed that when the antistatic layer contains polyester, deformation due to foreign matter adhesion is reduced.

[0223] Furthermore, a comparison of Examples 5 and 7-11 confirmed that when the silicon atom content (surface Si ratio) of the release layer is 2-10 atoms, the peel strength of the ceramic green sheet is low and the peelability of the release layer surface is superior.

[0224] [Comparative Example 2] Composition B6 for forming an antistatic layer is obtained by mixing the components shown below. A biaxially oriented polyester film is prepared in the same manner as in Example 6, except that composition B6 for forming an antistatic layer is used instead of composition B5 for forming an antistatic layer, and the thickness of the antistatic layer is set to 40 nm.

[0225] <Composition B6 for forming an antistatic layer> • Composition Y1 (solid content concentration 13% by mass): 191.4 parts by mass • Distilled water: 808.6 parts by mass

[0226] In Comparative Example 2, the prepared biaxially oriented polyester film was too smooth on both sides, making it difficult to wind into a roll, and thus difficult to evaluate deformation due to foreign matter adhesion and feed-through charging. On the other hand, the polyester film in Comparative Example 2 had a roller charge of 70 pC, which is higher than the roller charge of each example, so it is presumed that foreign matter adheres easily to it, and that deformation due to foreign matter adhesion is more likely to occur.

Claims

1. The material comprises an antistatic layer, a polyester substrate, and a release layer in this order, wherein the polyester substrate is substantially particle-free, the maximum protrusion height Sp on the surface of the release layer is less than 60 nm, the antistatic layer contains particles, and the surface resistance of the surface of the antistatic layer is 1.0 × 10⁻⁶. １１ A polyester film with a density of less than Ω / □.

2. The polyester film according to claim 1, wherein the maximum protrusion height Sp on both surfaces of the polyester film is less than 60 nm.

3. The polyester film according to claim 1 or 2, for use in manufacturing ceramic green sheets.

4. The polyester film according to claim 1 or 2, wherein the antistatic layer comprises a mixture of polyethylenedioxythiophene and polystyrene sulfonate.

5. The polyester film according to claim 4, wherein the antistatic layer comprises at least one selected from the group consisting of a binder having a sulfo group, a binder not having an acid group, and a binder having a carboxylic acid group and having an acid value of 10 mg KOH / g or less.

6. The polyester film according to claim 1 or 2, wherein the indentation modulus of the antistatic layer, as measured by an atomic force microscope, is 1.5 to 8.0 GPa.

7. The polyester film according to claim 1 or 2, wherein the antistatic layer comprises at least one selected from the group consisting of polyester, polyurethane, or acrylic resin.

8. The polyester film according to claim 1 or 2, wherein the antistatic layer contains a surfactant.

9. The polyester film according to claim 1 or 2, wherein the silicon atom content on the surface of the release layer is 1 to 15 atm%.

10. The polyester film according to claim 1 or 2, wherein the release layer comprises at least one resin selected from the group consisting of acrylic resin having siloxane bonds and urethane resin having siloxane bonds.

11. The resin is -Si(R) ３ The polyester film according to claim 10, having a structure represented by , wherein R independently represents an alkyl group or an aryl group.

12. The polyester film according to claim 1 or 2, wherein the antistatic layer is a layer formed by in-line coating.

13. The polyester film according to claim 12, wherein the release layer is a layer formed by in-line coating.

14. The polyester film according to claim 1 or 2, wherein the antistatic layer and the polyester substrate are in contact, and the polyester substrate and the release layer are in contact.

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