Laminated polyester film

Abstract

This laminated polyester film is obtained by laminating a resin layer Y on at least one side of a polyester film with a resin layer X therebetween, the resin layer X containing at least two kinds of a compound A having a vinyl alcohol residue and a compound B having a thiophene structure.　Provided is a laminated polyester film which has excellent antistatic properties and heat resistance, and is thus suitably used as a process film for various industrial product manufacturing processes.

Description

Laminated Polyester Film

[0001] The present invention relates to a laminated polyester film having excellent antistatic properties and heat resistance.

[0002] Polyester films have excellent properties such as mechanical properties, electrical properties, dimensional stability, transparency, and chemical resistance, and are therefore widely used as magnetic recording materials, optical materials, and industrial materials.

[0003]

[0003] In recent years, there has been an increasing demand for films that have excellent releasability, antistatic properties, and resistance to heat applied during the processing of various industrial products, as protective films for pressure-sensitive adhesive layers in pressure-sensitive adhesive products and process films for various industrial products. Under these circumstances, a film having an antistatic release layer has been disclosed (Patent Document 1). Also, a film having an underlayer provided between a polyester film substrate and an antistatic release film substrate has been disclosed (Patent Document 2).

[0004] JP 2019-66888 A JP 2014-141557 A

[0005] However, in the case of a laminated film in which antistatic properties have been imparted to the release layer, when heat is applied to the film, there is a problem that the antistatic agent contained in the release layer bleeds out, deteriorating the antistatic properties and contaminating the process.

[0006] In order to solve the above problems, the laminated polyester film of the present invention has the following configuration. That is, <1> a laminated polyester film having, on at least one surface of a polyester film, a resin layer X containing at least a compound A having a vinyl alcohol residue and a compound B having a thiophene residue. <2> the laminated polyester film according to <1>, in which the epoxy group content in the solid content of the resin layer X determined from the laminated polyester film under specific extraction and analysis conditions is 5 mg / g or more and 100 mg / g or less. <3> the laminated polyester film according to <1> or <2>, in which, when the converted mass of the resin layer X of the laminated polyester film is taken as 100 mass%, the total amount of organic components in the solid content of the resin layer X extracted under specific extraction conditions is 90 mass% or more. <4> the laminated polyester film according to any one of <1> to <3>, in which, based on 100 mass% of the resin layer X, the total content of the compound A having a vinyl alcohol residue, the compound B having a thiophene residue, and the epoxy compound C is 90 mass% or more. <5> the laminated polyester film according to any one of <1> to <4>, in which the degree of polymerization of the compound A is 50 or more and 1,000 or less. <6> The laminated polyester film according to any one of <1> to <5>, in which the adhesion M(X) of the resin layer X satisfies the following condition:

[0007] [Correction based on Rule 91 27.06.2023] M(X)≧90(%)<7> A method for producing a laminated polyester film according to any one of <1> to <6>, comprising the steps of applying a coating agent for forming the resin layer X to a polyester film and stretching the polyester film, in this order.<8> The laminated polyester film according to any one of <1> to <6>, comprising a polyester film, the resin layer X, and a resin layer Y, in this order.<9> The laminated polyester film according to <8>, in which the surface resistivity of the surface of the resin layer Y satisfies the following formulas (1) and (2): (1) 10 ６ ≦Ω(0)≦10 １０ (2) Omega （１５０） / Ω （０） <50, where Ω(0): surface resistivity (Ω / sq) of the surface of the resin layer Y before heat treatment, Ω （１５０）HYp-HYa|≦100°。 (3) 0°≦HYa≦80° (4) 10°≦|HYp-HYa|≦100° Where, HYp is the water contact angle of the resin layer Y surface of the laminate polyester film, and HYa is the water contact angle of the resin layer Y surface of the laminate polyester film after heat treatment at 150°C for 60 minutes. <10> The laminate polyester film according to <8> or <9>, wherein the surface free energy of the resin layer Y is 30 mN / m or less. <11> The laminate polyester film according to any one of <8> to <10>, wherein the resin layer Y is a resin containing a compound having a siloxane bond as a main component. <12> The laminate polyester film according to any one of <8> to <11>, wherein the water contact angle of the resin layer Y surface satisfies the following formulas (3) and (4): (3) 0°≦HYa≦80° (4) 10°≦|HYp-HYa|≦100°. Here, HYp is the water contact angle of the resin layer Y surface of the laminate polyester film, and HYa is the water contact angle of the resin layer Y surface of the laminate polyester film after immersing the laminate polyester film in pure water at 25°C for 5 minutes. <13> The laminated polyester film according to any one of <8> to <12>, which has a haze change (hereinafter sometimes referred to as "Δ haze") after heat treatment at 150°C for 60 minutes of 10% or less. <14> The laminated polyester film according to any one of <8> to <13>, which has a solvent resistance of the surface of the resin layer Y determined in accordance with JIS L 0849 (2013) (friction tester type II) of 50% or more and 100% or less. <15> The laminated polyester film according to any one of <8> to <14>, which is used as a process film in a product manufacturing process.

[0008] According to the present invention, it is possible to provide a laminated polyester film that has excellent antistatic properties and heat resistance and is suitable for use as a protective film for the pressure-sensitive adhesive layer in pressure-sensitive adhesive products and as a process film in the processing of various industrial products.

[0009] The present invention will be described in detail below with reference to specific examples.

[0010] The present invention relates to a laminated polyester film having one or more layers provided on at least one side of a polyester film. The polyester referred to in the present invention comprises a dicarboxylic acid component and a diol component. In this specification, the term "component" refers to the smallest unit obtainable by hydrolysis of a polyester. Examples of dicarboxylic acid components constituting such polyesters include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, and 4,4'-diphenyletherdicarboxylic acid, as well as ester derivatives thereof.

[0011] Examples of diol components constituting such polyesters include aliphatic diols such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,2-butanediol, and 1,3-butanediol, alicyclic diols such as cyclohexanedimethanol and spiroglycol, and diols in which multiple units of the above-mentioned diols are linked together. Among these, from the viewpoints of mechanical properties and transparency, polyesters that are preferably used are polyethylene terephthalate (PET), polyethylene-2,6-naphthalenedicarboxylate (PEN), and polyesters in which isophthalic acid or naphthalenedicarboxylic acid is copolymerized with a portion of the dicarboxylic acid component of PET, and polyesters in which cyclohexanedimethanol, spiroglycol, or diethylene glycol is copolymerized with a portion of the diol component of PET.

[0012] The laminated polyester film of the present invention preferably has a resin layer X containing at least a compound A having a vinyl alcohol residue and a compound B having a thiophene residue on at least one surface of the polyester film.

[0013] Because the compound B is conductive, the resin layer X containing the compound B can exhibit antistatic properties. Furthermore, because the compound A has a large number of electron-rich hydroxyl groups, it interacts with the π-conjugated electrons of the compound B, improving the fluidity of the rigid compound B and improving the film-forming properties of the resin layer X. As a result of the improved film-forming properties of the resin layer X, the compound B can be uniformly present on the surface of the polyester film, sufficiently reducing the surface resistivity of the laminated polyester film and improving the antistatic properties of the laminated polyester film. Furthermore, as a result of the improved film-forming properties of the resin layer X, the resin layer X can uniformly cover the surface of the polyester film. As a result, when the film is heat-treated, the oligomer contained in the polyester film can be prevented from bleeding out onto the surface of the resin layer X, resulting in a laminated film with little haze change due to heating, i.e., high heat resistance.

[0014] In the film of the present invention, the resin layer X contains compound A and compound B, and the fluidity of compound B is improved, which results in suppressing the occurrence of minute defects in the resin layer X, such as minute coating voids and microcracks, and also suppressing the bleed-out of oligomers contained in the polyester film onto the surface of the resin layer X, resulting in a laminate film with particularly high heat resistance.

[0015] The compound A having a vinyl alcohol residue herein refers to a compound that contains ions generated from polyvinyl alcohol as a generation source when the laminated polyester film is measured by the method described below, and the compound B having a thiophene residue herein refers to a compound that contains ions generated from polythiophene as a generation source when the laminated polyester film is measured by the method described below.

[0016] A polythiophene-based compound can be preferably used as compound B having a thiophene residue. Polythiophene compounds are generally π-electron conjugated compounds and have electrical conductivity, so compound B can impart antistatic properties to resin layer X. Examples of polythiophene-based compounds include compounds having a structure in which the 3rd and 4th positions of the thiophene ring are substituted. Furthermore, compounds in which oxygen atoms are bonded to the 3rd and 4th carbon atoms of the thiophene ring are preferably used. Compounds in which a hydrogen atom or a carbon atom is directly bonded to the carbon atom may not be easily dispersed in water. The above compounds can be produced by, for example, the methods disclosed in JP-A-2000-6324, EP-A-602713, and U.S.-A-5391472, but other methods may also be used.

[0017] [Correction based on Rule 91, 27 June 2023] For example, 3,4-ethylenedioxythiophene can be obtained from an alkali metal salt of 3,4-dihydroxythiophene-2,5-dicarboxyester as a starting material. Then, potassium peroxodisulfate, iron sulfate, and the previously obtained 3,4-ethylenedioxythiophene are introduced into an aqueous solution of polystyrene sulfonic acid and reacted to obtain a composition in which a polythiophene such as poly(3,4-ethylenedioxythiophene) is complexed with an acidic polymer such as polystyrene sulfonic acid. By complexing with an acidic polymer, the acidic function of the acidic polymer also functions as a doping agent for the polythiophene, which is preferable because it leads to improved antistatic properties.

[0018] Furthermore, an aqueous coating composition containing poly-3,4-ethylenedioxythiophene and polystyrene sulfonic acid, such as that sold under the trade name "Baytron" P by H. C. Starck GmbH (Germany), can be used.

[0019] On the other hand, examples of acidic polymers include polymeric carboxylic acids, polymeric sulfonic acids, and polyvinyl sulfonic acids. Examples of polymeric carboxylic acids include polyacrylic acid, polymethacrylic acid, and polymaleic acid. Examples of polymeric sulfonic acids include polystyrene sulfonic acid, with polystyrene sulfonic acid being particularly preferred for its antistatic properties. These acidic polymers may be in the form of partially neutralized salts. They may also be used in the form of copolymers with other copolymerizable monomers, such as acrylic acid esters, methacrylic acid esters, and styrene. The molecular weight of the polymeric carboxylic acid or polymeric sulfonic acid is not particularly limited. However, from the viewpoint of coating stability and antistatic properties, the weight-average molecular weight is preferably 1,000 to 1,000,000, and more preferably 5,000 to 150,000. Furthermore, alkali salts such as lithium salts and sodium salts, or ammonium salts, may be included in the polymeric carboxylic acids, as long as they do not impair the properties of the invention. Neutralized salts of polyanions are also believed to function as dopants. This is because polystyrene sulfonic acid and its ammonium salt, which function as very strong acids, shift the equilibrium to the acidic side as the equilibrium reaction progresses after neutralization.

[0020] Polyvinyl alcohol can be suitably used as the compound A having a vinyl alcohol residue. Polyvinyl alcohol has many electronically rich hydroxyl groups, which interact with the π-conjugated electrons of the polythiophene system and improve the fluidity of the rigid polythiophene molecular chains. As a result, when the resin layer X is applied using an in-line coating method during the formation of a polyester film, improved film-forming properties are achieved, such as improved coatability and stretchability of the resin layer X. As a result of this improved film-forming properties, the conductive polythiophene compound is uniformly present on the surface of the polyester film, thereby reducing the surface resistivity of the laminated polyester film and improving the antistatic properties of the laminated polyester film. Furthermore, the improved film-forming properties of the resin layer X allow the resin layer X to uniformly cover the surface of the polyester film when formed using an in-line coating method. As a result, for example, when a laminated polyester film having the resin layer X is heat-treated, oligomers contained in the polyester film are less likely to bleed out onto the surface of the resin layer X, improving heat resistance.

[0021] The degree of saponification of polyvinyl alcohol is preferably 70 to 100, more preferably 80 to 100. Polyvinyl alcohol has hydroxyl groups and acetate groups as side chains, and the higher the degree of saponification, the greater the amount of hydroxyl groups. Therefore, the higher the degree of saponification, the more easily the above-mentioned effects can be obtained.

[0022] The degree of polymerization of compound A is preferably from 50 to 1,000, more preferably from 100 to 800, and even more preferably from 300 to 600. When the degree of polymerization is within the above preferred range, the fluidity of the rigid polythiophene molecular chain can be improved, and the coating property is also good, making lamination easy.

[0023] In addition, it is also a preferred embodiment to use a copolymerized polyvinyl alcohol in which a functional group other than a hydroxyl group or an acetate group is copolymerized as a side chain of the polyvinyl alcohol-based resin used for the resin layer X. In particular, it is also preferable to introduce a hydrophilic functional group, such as a 1,2-ethanediol group, a carboxyl group, or a sodium sulfonate group. The copolymerization amount is preferably 1 mol % or more and 20 mol % or less, and more preferably 3 mol % or more and 10 mol % or less, based on the entire polyvinyl alcohol resin. When the copolymerization amount is within the above preferred range, the coating property is good and lamination becomes easy.

[0024] The laminated polyester film of the present invention preferably has an epoxy group content in the solid content of the resin layer X determined from the laminated polyester film under the following specific extraction and analysis conditions of 5 mg / g or more and 100 mg / g or less. ２ After cutting and cutting, the material is placed in a flask with 80 mL of water and subjected to ultrasonic cleaning at 40 kHz and 360 W for 30 minutes to extract layer X. The resulting aqueous solution is filtered to remove impurities, and then the solvent is removed by freeze-drying to obtain a solid. <Analysis conditions> The resulting solid is extracted with heavy water and freeze-dried under the following conditions. １ H NMR is measured. The epoxy groups are quantified based on the peak area derived from the epoxy groups. Apparatus: ECZ-600R (manufactured by JEOL RESONANCE Co., Ltd.) Measurement method: Single pulse Measurement frequency: 600.17 MHz Pulse width: 5.88 μs Chemical shift reference: TSP (sodium 3-trimethylsilylpropionate-2,2,3,3-d ４ ) (0 ppm) Number of accumulations: 16 Measurement temperature: 20°C Sample rotation speed: 15 Hz When acquiring the spectrum, a known amount of sodium 3-(trimethylsilyl)propionate (TSP) is added as an internal standard substance. From the spectrum obtained, the peak area Ea observed at 2.7 ppm, which is derived from the epoxy group, and the peak area Ta observed at 0 ppm, which is derived from the internal standard substance, are calculated. From the ratio of Ea to Ta and the amount of the added standard sample, the amount of epoxy groups corresponding to Ea is calculated and used as the amount of epoxy groups in layer X.

[0025] Examples of a state in which the epoxy group content in the solid content of the resin layer X obtained by the above method is less than 5 mg / g include a state in which the resin layer X does not contain an epoxy compound, a state in which even if the resin layer X contains an epoxy compound, a state in which the crosslinking reaction by the crosslinking agent or binder has progressed excessively, or a state in which the resin layer X is insoluble in water.

[0026] When the epoxy group content in the solid content of the resin layer X determined by the above method is 5 mg / g or more, the film-forming properties of the resin layer X are improved, compound B can be more uniformly present on the surface layer of the polyester film, the surface resistivity of the laminated polyester film is reduced, and the antistatic properties of the laminated polyester film can be improved. Furthermore, when the polyester film is immersed in water, water can easily penetrate into the resin layer X, making it easy to extract and remove the resin layer X with water and wash the film. Furthermore, when the epoxy group content in the solid content of the resin layer X determined by the above method is 100 mg / g or less, the film-forming properties of the resin layer X can be improved.

[0027] In order to set the epoxy group content in the solid content of the resin layer X of the laminated polyester film of the present invention within the above range, it is a preferred embodiment to contain an epoxy compound (compound C) in addition to compound A and compound B. As compound C, for example, a sorbitol polyglycidyl ether-based compound, a polyglycerol polyglycidyl ether-based compound, a polyethylene glycol diglycidyl ether-based compound, a polyhydroxyalkane polyglycidyl ether-based compound, or the like can be used. For example, epoxy compounds "Denacol" (EX-611, EX-614, EX-614B, EX-512, EX-521, EX-421, EX-313, EX-810, EX-830, EX-850, etc.) manufactured by Nagase ChemteX Corporation, diepoxy / polyepoxy compounds (SR-EG, SR-8EG, SR-GLG, etc.) manufactured by Sakamoto Pharmaceutical Co., Ltd., and epoxy crosslinking agents "EPICLON" (EM-85-75W, CR-5L) manufactured by DIC Corporation can be suitably used, and among these, those having water solubility are preferred.

[0028] Because the epoxy compound has a three-membered ring containing an oxygen atom, the electrons of the oxygen atom easily interact with other molecules. In the film of the present invention, the epoxy compound interacts with compound B having a thiophene residue contained in resin layer X, improving the fluidity of the rigid polythiophene molecular chain. As a result, when resin layer X is applied using an in-line coating method in which resin layer X is formed during the film formation of a polyester film, the improved coatability and stretchability of resin layer X result in improved film-formability of resin layer X. As a result of the improved film-formability of resin layer X, the polythiophene-based compound, which is a conductive resin, is uniformly present on the surface layer of the polyester film, thereby reducing the surface resistivity of the laminated polyester film and improving the antistatic properties of the laminated polyester film.

[0029] Furthermore, as a result of the improved fluidity of the resin layer X, when the polyester film of the present invention is immersed in water, water easily penetrates into the resin layer X. As a result, the compound A having a vinyl alcohol residue contained in the resin layer X is eluted in water, and as a result, the resin layer X can be extracted with water. Since the resin layer X can be extracted with water, it is possible to wash the resin layer X with water or the like and recover only the polyester film, which can be reused.

[0030] In order to improve the fluidity of the resin layer X, the molecular weight of the compound C is 10,000 or less, preferably 5,000 or less, and more preferably 1,000 or less.

[0031] In order to improve the fluidity of the resin layer X and improve its extractability with water, it is preferable that the total amount of organic components in the solid content of the resin layer X extracted under the following specific extraction conditions be 90% by mass or more, when the converted mass of the resin layer X of the laminated polyester film of the present invention is taken as 100% by mass. ２ After cutting and cutting, the resin layer X is extracted from the resin by ultrasonic cleaning for 30 minutes at 40 kHz and 360 W. The resulting aqueous solution is filtered to remove impurities, and then the solvent is removed by freeze-drying to obtain a solid content.

[0032] The converted mass of the resin layer X is determined by measuring the thickness of the resin layer X by the method described below, calculating the volume of the resin layer X, and then multiplying the result by a density of 1.0, which is the density of the organic component. That is, it is preferable that the percentage of the value obtained by dividing the mass of the solid content of the resin layer X obtained by the specific extraction method by the converted mass of the resin layer X is 90 mass% or more.

[0033] This embodiment makes it possible to extract the resin layer X with water, thereby allowing the resin layer X to be washed with water or the like, and the polyester film alone to be recovered and reused.

[0034] In order to keep the total amount of organic components extracted under the above extraction conditions within the above range, it is preferable that the resin layer X does not contain a resin having crosslinking points with other components, i.e., a binder resin having an N (nitrogen) element or a carbonyl group, such as a urethane resin, a polyester resin, an acrylic resin, etc. If the resin layer does not contain a binder resin having an N element or a carbonyl group having crosslinking points with other components, it is difficult to form a crosslinked structure with, for example, the compound A of the present invention, and the resin layer will not become hydrophobic, making it possible to extract the resin layer X under the above conditions.

[0035] That is, in order to enable extraction of the resin layer X under the above conditions, in the laminated polyester film of the present invention, the total content of the compound A having a vinyl alcohol residue, the compound B having a thiophene residue, and the epoxy compound C is preferably 90% by mass or more, and the total content of the compounds A to C is more preferably 95% by mass or more, further preferably 98% by mass or more, and particularly preferably 99% by mass or more, relative to 100% by mass of the resin layer X.

[0036] The ratio of compound A to compound C contained in resin layer X in the laminated polyester film of the present invention is preferably 10 parts by mass or more and 300 parts by mass or less, more preferably 20 parts by mass or more and 180 parts by mass or less, relative to 100 parts by mass of compound A. When the ratio of compound A to compound C contained in resin layer X is within the above preferred range, the resin layer X has excellent antistatic properties and excellent water extractability.

[0037] The resin layer X in the present invention preferably has an adhesion M(X) that satisfies the following condition.

[0038] M(X)≧90(%) In the present invention, the adhesion M(X) of the resin layer X is measured as follows.

[0039] Cuts are made in a 5 cm square of a film having a resin layer X with a weight of 10 g so that each square is 0.5 cm square. When a 31B tape manufactured by Nitto Denko Corporation is applied to the cut area and then peeled off, the number of squares in which the resin layer X has not migrated to the tape side is counted and expressed as a percentage.

[0040] The adhesion M(X) of the resin layer X satisfying the above range means that the adhesion between the resin layer X and the polyester film is high. This embodiment makes it possible to improve the heat resistance of the laminated polyester film. A preferred method for achieving the adhesion M(X) of the resin layer X within the above range is to incorporate compound A and compound B into the resin layer X to improve film-forming properties. Another preferred embodiment of the method for forming the resin layer X is to use a so-called in-line coating method, which includes, in this order, the steps of applying the coating agent for forming the resin layer X to the polyester film and stretching the polyester film. In the in-line coating method, the resin layer X is formed while stretching the polyester film. As the polyester film is stretched, the contact area between the polyester film and the resin layer X increases, thereby improving adhesion. As a result, it is possible to achieve M(X) within the above range.

[0041] [Correction based on Rule 91, 27 June 2023] The laminated polyester film of the present invention preferably comprises a polyester film, the resin layer X, and the resin layer Y, in this order. The resin layer Y is located at the outermost layer of the laminated polyester film and is a functional layer that exhibits the performance of the laminated polyester film. By laminating the resin layer Y on the outermost layer via the antistatic resin layer X, the resin layer Y exhibits antistatic properties. This not only prevents process contamination due to bleed-out of components contained in the resin layer X, such as components that exhibit antistatic properties, when the laminated film of the present invention is subjected to heat during processing, but also prevents deterioration of the laminate film's functionality. Furthermore, when the polyester film of the present invention is used as a process film, the resin layer Y is preferably composed of a resin with releasability. Examples of resins with releasability include silicone compounds primarily containing a compound with a siloxane bond, compounds with a long-chain alkyl group, and compounds containing fluorine. Here, "resin layer Y primarily containing a compound with a siloxane bond" means that the compound contains 80 mol% or more of a moiety with a siloxane bond. Among these, silicone compounds (organopolysiloxanes) mainly composed of compounds having highly hydrophobic siloxane bonds are preferred, and resins made of curable silicone compounds are particularly suitable. Examples of resins made of curable silicone compounds include an "addition reaction type" in which an organohydrogenpolysiloxane and an organopolysiloxane containing an alkenyl group are heat-cured using a platinum catalyst, a "condensation reaction type" in which an organohydrogenpolysiloxane and an organopolysiloxane containing a terminal hydroxyl group are heat-cured using an organotin catalyst, a "UV curing type" in which a photopolymerization initiator is added to an organopolysiloxane containing an acryloyl group or a methacryloyl group, or an organopolysiloxane containing an alkenyl group and an organopolysiloxane containing a mercapto group, and the resulting resin is cured by irradiating UV light, and a "cationic polymerization type" in which an epoxy group is photo-opened using an onium salt initiator to cause curing.In particular, when a resin having a vinyl alcohol residue is used for the resin layer X, an addition reaction type organopolysiloxane obtained by heat-curing an organohydrogenpolysiloxane and an organopolysiloxane containing an alkenyl group using a platinum catalyst is preferred for the reasons described below. From the viewpoints of hydrophobicity and compound production, dimethylpolysiloxane is preferred as the organopolysiloxane.

[0042] In the laminated polyester film of the present invention, it is preferable that the surface resistivity of the surface of the resin layer Y satisfies the following formulas (1) and (2): ６ ≦Ω(0)≦10 １０ (2) Omega （１５０） / Ω （０） <50 In formula (1) and formula (2), Ω （０） : surface resistivity (Ω / sq) of the surface of the resin layer Y before heat treatment, Ω （１５０） : represents the surface resistivity (Ω / sq) of the surface of the resin layer Y after heat treatment at 150° C. for 60 minutes.

[0043] Ω （０） By satisfying the above formula (1), the laminated polyester film has sufficient antistatic properties, and when used as a film for processing, it is easy to peel off an object to be released from the film. On the other hand, the conductivity is not excessively high, so that it is possible to prevent short circuits when used in various processes.

[0044] Ω （１５０） / Ω （０） When the value of the antistatic property of the surface of the resin layer Y of the laminated polyester film of the present invention is in the above range, the antistatic property of the surface of the resin layer Y of the laminated polyester film of the present invention is less likely to be impaired by heat, and when the laminated polyester film of the present invention is used as a processing film, it is less affected by heating in the processing, which is preferable because the film can be used as a variety of processing films.

[0045] In order to satisfy the above formula (2), the amount of antistatic agent contained in resin layer Y, which is the outermost layer of the laminated polyester film, is preferably 0.1 mass % or less relative to resin layer Y, and particularly preferably, substantially no antistatic agent is contained. The antistatic agent referred to here is a material that exhibits antistatic properties when contained in resin layer Y. Examples of such materials include ion-conductive polymer compounds such as ammonium group-containing compounds, polyether compounds, sulfonic acid compounds, and betaine compounds, and π-electron conjugated polymer compounds such as polyacetylene, polyphenylene, polyaniline, polypyrrole, polyisothianaphthene, and polythiophene. When resin layer Y does not substantially contain an antistatic agent, the antistatic agent is less likely to bleed out to the outermost surface of the laminated polyester film even when heat is applied to the laminated polyester film, thereby maintaining the inherent conductivity of the laminated polyester film and satisfying formula (2).

[0046] Furthermore, in order to satisfy the above formulas (1) and (2), it is preferable that the resin layer Y contains substantially no antistatic agent, and that the layer in contact with the resin layer Y is a layer having antistatic properties. Furthermore, in order to satisfy the above formula (1), the thickness of the resin layer Y is preferably 300 nm or less, more preferably 100 nm or less, and even more preferably 50 nm or less. The thickness of the resin layer Y is preferably 20 nm or more because it serves as a functional layer of the resin layer Y. By setting the thickness of the resin layer Y within the above range, the antistatic properties of the layer in contact with the resin layer Y (resin layer X in the laminated polyester film of the present invention) make it easier to satisfy the above formula (1).

[0047] In the film of the present invention, resin layer X contains compound A having a vinyl alcohol residue and compound B having a thiophene residue, and the interaction between compound A and compound B improves the fluidity of layer X, thereby preventing the occurrence of fine defects in resin layer X, such as fine coating voids and microcracks, and when resin layer Y is provided in contact with resin layer X to form a laminated polyester film, the occurrence of fine defects in resin layer Y, such as fine coating voids and microcracks, can be prevented. As a result, when the laminated polyester film of the present invention is heated, oligomers generated from the polyester film are less likely to bleed out into resin layer Y, improving heat resistance and making it possible to set the above formula (2) within a preferred range.

[0048] Furthermore, from the viewpoint of heat resistance, the compound having antistatic properties contained in the resin layer X is preferably a compound B having a thiophene residue, and is particularly preferably a polythiophene-based compound. In particular, when the resin layer X contains the compound B, which is a high molecular weight compound, the antistatic agent contained in the resin layer X can be prevented from bleeding out into the resin layer Y and reducing heat resistance, as compared with when the resin layer X contains an antistatic agent that is a low molecular weight compound.

[0049] When an addition-reaction-type organopolysiloxane is used for resin layer Y of the laminated polyester film of the present invention, the organopolysiloxane is obtained by addition reaction of a hydrogenorganopolysiloxane with an alkenyl group-containing organopolysiloxane via a platinum catalyst, but it is known that hydrogenorganopolysiloxanes also undergo condensation reactions with compounds having hydroxyl groups via a platinum catalyst (International Publication No. WO 2014 / 099497). When resin layer Y contains a hydrogenorganopolysiloxane and resin layer X in contact with resin layer Y contains polyvinyl alcohol, the hydrogenorganopolysiloxane and polyvinyl alcohol condense, improving adhesion at the interface between resin layer X and resin layer Y, which is preferred. As a result of the improved adhesion between the resin layer X and the resin layer Y, even when heat is applied to a laminated polyester film having the resin layer X and the resin layer Y, the oligomer contained in the polyester film does not precipitate on the surface, and the antistatic properties, transparency, and releasability of the laminated polyester film are not impaired, and it becomes possible to satisfy the above formulas (1) and (2).

[0050] It is preferable that the resin layer X does not contain a resin having a crosslinking point with other components, i.e., a binder resin having an N (nitrogen) element or a carbonyl group, such as a urethane resin, a polyester resin, an acrylic resin, etc. When the resin layer X does not contain a binder resin having an N element or a carbonyl group having a crosslinking point with other components, for example, the compound A of the present invention and the binder resin do not form a crosslinked structure, and therefore, the effect of improving the adhesion at the interface between the resin layer Y and the resin layer X can be obtained.

[0051] The surface free energy of the resin layer Y of the laminate film of the present invention is preferably 30 mN / m or less, more preferably 15 mN / m or less. Although no lower limit is particularly set, it is greater than 0 mN / m based on the method for calculating the surface free energy. When the surface free energy of the resin layer Y is in the above preferred range, when the laminate polyester film is used as a process film, particularly as a process film for releasing an object to be released, the releasability of the object to be released is excellent.

[0052] [Correction based on Rule 91, 27.06.2023] The haze change of the laminate film of the present invention after heat treatment at 150°C for 60 minutes is preferably 10% or less, more preferably 5% or less. While no lower limit is specifically set, it is 0% or more based on the calculation method for haze change. When the haze change after heat treatment at 150°C for 60 minutes is within the above-mentioned preferred range, less oligomer precipitates on the surface of the laminate film, making it easy to control the surface resistivity of the resin layer Y surface to a preferred value. Furthermore, the laminate film exhibits excellent performance when used as a process film in the processing of various industrial products.

[0053] In the laminated polyester film of the present invention, it is preferable that the solvent resistance rate of the surface of the resin layer Y determined in accordance with JIS L 0849 (2013) (friction tester type II) is 50% or more and 100% or less.

[0054] As described above, the adhesion between the resin layer X and the resin layer Y is improved, which improves the abrasion resistance of the resin layer Y and makes it possible to set the solvent resistance rate within a preferred range. The upper limit of the solvent resistance rate is 100%. When the solvent resistance rate is within the above preferred range, the film can be suitably used as a process film.

[0055] In the laminated polyester film of the present invention, the water contact angle on the Y surface of the resin layer preferably satisfies the following formulas (3) and (4): (3) 0°≦HYa≦80° (4) 10°≦HYp−HYa≦100°, where HYp represents the water contact angle on the Y surface of the resin layer of the laminated polyester film, and HYa represents the water contact angle on the Y surface of the resin layer of the laminated polyester film after the laminated polyester film is immersed in pure water at 25° C. for 5 minutes.

[0056] The fact that the laminated polyester film of the present invention satisfies the above formulas (3) and (4) means that the water contact angle of the resin layer Y changes after immersion in pure water at 25° C. for 5 minutes, and also means that the water contact angle after immersion in pure water at 25° C. is not too large, i.e., it can be made close to the water contact angle of a polyester film, and the resin layer Y is in a state where it can be washed with water and peeled off. Satisfying this aspect makes it possible to wash the resin layer Y with water, which is preferable because when the laminated polyester film of the present invention is washed by the method described below, the polyester film as the substrate can be easily removed and reused.

[0057] As a method for making the laminated polyester film of the present invention satisfy the above formula (3), it is also a preferred embodiment to make the resin layer X easily extractable with water. Also from the viewpoint of making the resin layer X easily extractable with water, it is preferred that the epoxy group content in the solid content of the resin layer X is 5 mg / g or more and 100 mg / g or less.

[0058] From the viewpoint of mold releasability, it is more preferable that HYp≧90°.

[0059] The ratio of compound A to compound B contained in resin layer X in the laminated polyester film of the present invention is 10 parts by mass or more and 700 parts by mass or less of compound B relative to 100 parts by mass of compound A, and more preferably 10 parts by mass or more and 300 parts by mass or less. When the ratio of compound A to compound B contained in resin layer X is within the above preferred range, excellent antistatic properties and excellent film-forming properties are obtained, resulting in excellent heat resistance and antistatic properties.

[0060] Next, a method for producing the laminated polyester film of the present invention will be described below, but the present invention is not limited to the laminated polyester film obtained by this method.

[0061] The polyester film used in the present invention can be prepared by a method (melt casting method) in which, if necessary, dried raw materials are heated and melted in an extruder, extruded through a die onto a cooled casting drum, and processed into a sheet. The sheet is then cooled and solidified by static electricity on a drum cooled to a surface temperature of 20°C to 60°C, thereby producing an unstretched sheet. The temperature of the casting drum is preferably 20°C to 40°C, and even more preferably 20°C to 30°C.

[0062] Next, the unstretched sheet is biaxially stretched at a temperature T1n (°C) that satisfies the following formula (i), to a stretching ratio of 3.6 times or more in the longitudinal direction (MD) of the film, 3.9 times or more in the width direction (TD) of the film, and an area stretching ratio of 14.0 times or more and 20.0 times or less.

[0063] The stretching ratio in the film width direction is preferably 3.0 times or more, more preferably 3.5 times or more and 5.0 times or less. By setting the stretching ratio in the film width direction to 3.0 times or more, when the resin layer X is applied to the uniaxially stretched film using the in-line coating method described below, the components constituting the resin layer X are stretched and elongated along with the film, so that the resin layer X can be uniformly provided. When the stretching ratio in the width direction is within the above preferred range, the film has excellent film-forming properties. (i) Tg (°C) ≦ T1n (°C) ≦ Tg + 40 (°C) In the above formula (i), Tg represents the glass transition temperature (°C) of the polyester film.

[0064] A method using a speed difference between rolls is preferably used as a method for stretching the polyester film in the longitudinal direction. In this case, it is also a preferred embodiment to stretch the polyester film in multiple sections while fixing the polyester film with nip rolls to prevent the polyester film from slipping.

[0065] Next, the biaxially stretched polyester film is heat-set for 1 second to 30 seconds at a temperature (Th0 (°C)) that satisfies the following formula (ii), and then cooled uniformly and slowly to room temperature to obtain the polyester film used in the present invention: (ii) Tmf - 35 (°C) ≦ Th0 (°C) ≦ Tmf (°C) In the formula (ii), Tmf represents the melting point of the film (°C).

[0066] By obtaining a biaxially stretched film under the condition (ii), it is possible to impart an appropriate orientation to the film, thereby improving the handling properties when used as a release film.

[0067] Next, a method for providing the resin layer X and the resin layer Y on the polyester film will be described below.

[0068] When the resin layer X contains the compounds A and B as described above, particularly when compound B is obtained as an aqueous dispersion, a preferred method is to dissolve or disperse the compounds A and B forming the resin layer X in water and coat the polyester film of the present invention. Typical coating methods, such as gravure coating, Mayer bar coating, air knife coating, and doctor knife coating, can be used as the coating method. In particular, from the viewpoint of uniformly forming the resin layer X, an in-line coating method is preferably used, in which the resin of the resin layer X is coated on the surface of the polyester film after uniaxial stretching in the longitudinal direction, and the polyester film is stretched in the width direction while simultaneously forming the resin layer X. The thickness of the resin layer X is preferably 50 nm or more and 1,000 nm or less. When the thickness of the resin layer X is within the above preferred range, the resin layer X can uniformly cover the polyester film surface, blocking is less likely to occur, and handling is excellent.

[0069] Next, a method for providing the resin layer Y will be described. The resin layer Y may be provided simultaneously with the resin layer X, or separately. When providing them simultaneously, examples include a method of simultaneously coating the two layers using a die or the like, or a method of coating using a coating agent in which the components of the resin layer X and the components of the resin layer Y are premixed. To improve the lamination accuracy of the resin layer X and the resin layer Y, it is preferable to provide the resin layer X and the resin layer Y separately. A coating solution containing the components of the resin layer Y dissolved in the coating solution can be applied to the laminated polyester film containing the resin layer X obtained by the above-mentioned method using a common coating method such as gravure coating, Mayer bar coating, air knife coating, or doctor knife coating. The thickness of the resin layer Y is preferably 10 nm or more and 1,000 nm or less. When the thickness of the resin layer Y is within the above preferred range, the function of the resin layer Y is fully exhibited, while the antistatic properties can also be fully exhibited.

[0070] [Correction based on Rule 91 27.06.2023] As described above, the laminated polyester film of the present invention can be suitably used as a release film for processing or as a laminated film with other functional layers by providing a resin layer X containing at least two types of compounds, namely, compound A having a vinyl alcohol residue and compound B having a thiophene residue, on at least one side of the polyester film, and then providing a resin layer Y having a release function.

[0071] Next, a method for washing the laminated polyester film of the present invention with water will be described below, but the method is not limited thereto.

[0072] [Correction based on Rule 91, 27.06.2023] The laminated polyester film of the present invention is preferably subjected to the following steps: unwinding the laminated polyester film; supplying warm water to the surface of the unwound laminated film to peel the surface laminated portion from the laminated film; and winding the peeled polyester film. The warm water temperature is preferably 50°C or higher and 120°C or lower. Within the above preferred temperature range, sufficient cleanability is obtained while not exceeding the glass transition temperature of the polyester film, thereby preventing film transport interference. The time during which the surface of the laminated polyester film is in contact with water is 5 seconds or higher, preferably 10 seconds or higher, and more preferably 30 seconds or higher and 600 seconds or lower. The step of supplying warm water to the surface of the unwound laminated film is preferably carried out in a water tank, with the entire laminated film covered. Covering the entire laminated polyester film with warm water generates water pressure in the film flow direction, improving cleanability. The film transport speed is 5 m / min or higher, preferably 10 m / min or higher, and more preferably 20 m / min or higher and 100 m / min or lower. It is also important to apply tension to the laminated polyester film when transporting it in this process. By applying tension, the surface of the laminated polyester film can be stretched, improving its cleanability. The tension is 5 N / m or more and 1,000 N / m or less, more preferably 20 N / m or more and 800 N / m or less, and more preferably 30 N / m or more and 500 N / m or less. When the tension is within the above preferred range, the surface of the laminated polyester film is stretched, resulting in excellent cleanability, while the film is less likely to wrinkle, resulting in excellent surface stretchability and good cleanability.

[0073] [Method of Evaluating Characteristics] (I) Residues of Compound A and Compound B Residues of the resin layer X or resin layer Y of the laminated polyester film were analyzed in the depth direction from the surface under the following conditions. ４ H ５ O － When ions are detected, it is assumed that the resin layer X contains vinyl alcohol residues, and C ６ H.S. －is detected, it is determined that the resin layer X contains a thiophene residue. <Measurement conditions> Apparatus: TOF.SIMS5 (manufactured by ION-TOF) Pulse width: 100 ns Secondary ion polarity: positive Post-stage acceleration: 9.5 kV Mass range (m / z): 0 to 1,500 Raster size: 40 μm square Number of scans: 64 scans Number of pixels (one side): 256 pixels Primary ion species: Bi Measurement vacuum level (before sample introduction): 4×10 －７ Pa or less Primary ion acceleration voltage: 30 kV Etching ions: Argon gas cluster ions.

[0074] (II) Thickness of each resin layer The thickness of each resin layer of the laminated polyester film is determined by the following method. A cross section of the laminated polyester film is cut out with a microtome in a direction parallel to the width direction of the film. The cross section is observed under a scanning electron microscope at a magnification of 5,000 times, and the thickness of each resin layer of the laminated polyester film is measured.

[0075] [Correction based on Rule 91 27.06.2023] (III) Surface resistivity (Ω / sq) After leaving the sample at 25°C and a relative humidity of 65% for 24 hours, measure the surface resistivity in that atmosphere using an Advantest Digital Ultra-High Resistance / Micro Ammeter R8340A at an applied voltage of 100 V. Five points are randomly selected from the laminated polyester film for measurement, and the average value is calculated to be the surface resistivity.

[0076] (III-1) Surface resistivity after heat treatment at 150°C for 60 minutes The laminated polyester film was cut into a 20 cm square, attached to a metal frame, and left to stand for 1 hour in a hot air oven (PH-302, manufactured by Tabai Espec Co., Ltd.) at 150°C. Thereafter, the laminated polyester film was removed from the metal frame, and the surface resistivity was measured in Ω according to Section C. （１５０） Let's say.

[0077] (IV) Haze change (Δ haze) (%) after heat treatment at 150°C for 60 minutes The laminated polyester film is cut into a 20 cm square piece, and the haze is measured and designated as H(0). The laminated polyester film is attached to a metal frame and left to stand for 1 hour in a hot air oven (PH-302, manufactured by Tabai Espec Co., Ltd.) at 150°C. Thereafter, the laminated polyester film is removed from the metal frame, and the haze is measured and designated as H(0). （１５０） Let's say. H （１５０） From H （０） The difference is subtracted to obtain the haze change (Δ haze) after heat treatment at 150° C. for 60 minutes.

[0078] The haze value is measured in accordance with JIS K 7136 (2000) using an NDH-5000 manufactured by Nippon Denshoku Industries Co., Ltd., at five randomly selected locations on the laminated polyester film, and the average value is calculated.

[0079] [Correction based on Rule 91 27.06.2023] (V) Solvent durability of resin layer Y This is measured using a Gakushin-type testing machine (compliant with JIS L 0849 (2013)) manufactured by Daiei Scientific Instruments Co., Ltd., in the following manner. [Rubbing treatment with solvent-impregnated cloth] The surface of the resin layer Y of the film is rubbed using the following testing machine and friction element. Testing machine: Gakushin-type testing machine (rubbing tester type II described in JIS L 0849 (2013)) Friction element: cotton cloth (golden width No. 3) impregnated with toluene Load: 1.0 kg Number of strokes: 30 back and forth [Peeling Treatment] A polyester adhesive tape (Nitto Denko Corporation No. 31B, width 19 mm) was attached to the portion of the resin layer Y surface that had been subjected to rubbing treatment with a solvent-impregnated cloth while being pressed with a 2.0 kg roller, and then left to stand for 24 hours in an atmosphere of 23 ° C. and 65% RH. After that, using a peel tester VPA-H200 manufactured by Kyowa Interface Science Co., Ltd., the peel force between the sample surface and the polyester adhesive tape was measured at a peel angle of 180 ° and a peel speed of 300 mm / min, and converted to a 50 mm width to determine the peel force F (B) of the resin layer Y surface after rubbing treatment with a solvent-impregnated cloth. The peel force F (A) of the resin layer Y surface before rubbing treatment with a solvent-impregnated cloth was also measured in the same manner, and the solvent durability was measured based on the following formula. Solvent durability (%) = F (A) / F (B) × 100.

[0080] (VI) Amount of copolymerization of compound A (mol %): １３ The copolymerization amount (mol %) is determined from the peak area of ​​the carbon signal of the modified group introduced in the CNMR spectrum and DEPT135 spectrum. Apparatus: ECZ-600R (manufactured by JEOL RESONANCE Co., Ltd.) Measurement method: Single １３ C pulse with inverse gated １ H decoupling Measurement frequency: 150.9 MHz Pulse width: 5.25 μs Lock solvent: D ２ O Chemical shift reference: TSP (0 ppm) Number of accumulations: 10,000 Measurement temperature: 20°C Sample rotation speed: 15 Hz.

[0081] (VII) Degree of Saponification of Compound A: The degree of saponification of Compound A is calculated by quantifying the amount of acetate groups contained in a sample by titration with an aqueous sodium hydroxide solution in accordance with JIS K 6726 (1994) Test Method for Polyvinyl Alcohol.

[0082] [Correction based on Rule 91 27.06.2023] (VIII) Average degree of polymerization of compound A According to JIS K 6726 (1994) Testing method for polyvinyl alcohol, a sample is completely saponified with an aqueous sodium hydroxide solution, and then the viscosity at 25°C is measured using an Ostwald viscometer, and the average degree of polymerization is calculated from the intrinsic viscosity.

[0083] [Correction based on Rule 91, 27.06.2023] (IX) Surface Free Energy (mN / m) Measured using a contact angle meter DM501 manufactured by Kyowa Interface Science Co., Ltd. and the accompanying analysis software FAMAS according to the following method: Using glycerol, ethylene glycol, formamide, and diiodomethane as standard liquids, the static contact angle of each liquid at 25°C was determined for the surface of resin layer Y. The static contact angle for each liquid, along with the dispersion component, polar component, and hydrogen bond component of the surface free energy of each liquid described in Non-Patent Document 1, were then introduced into the "Extended Hawks Equation of Hata and Kitazaki" described in Non-Patent Document (J. Panzer: J. Colloid Interface Sci., 44, 142 (1973)). The dispersion component, polar component, and hydrogen bond component of the surface free energy of layer Y were determined by solving the simultaneous equations, and the sum of these values ​​was taken as the surface free energy.

[0084] The static contact angle is measured by first leaving the sample at rest for 12 hours in an environment of 25°C, and then calculating the static contact angle using an image taken 30 seconds after the time when the droplet contacted the sample surface, based on the time 0 seconds, using the θ / 2 method. Measurement is performed five times at different locations, and the dispersion component, polar component, and hydrogen bond component of the surface free energy of the resin layer X and the resin layer Y are calculated using the average values ​​of the static contact angles.

[0085] (IX) Use as a process film (IX-1) For green sheet molding [Preparation of dielectric paste] Glass beads having a number average particle size of 2 mm are added to 100 parts by mass of barium titanate (manufactured by Fuji Titanium Kogyo Co., Ltd. under the trade name of HPBT-1), 10 parts by mass of polyvinyl butyral (manufactured by Sekisui Chemical Co., Ltd. under the trade name of BL-1), 5 parts by mass of dibutyl phthalate, and 60 parts by mass of toluene-ethanol (mass ratio 30:30), and the mixture is mixed and dispersed in a jet mill for 20 hours, followed by filtration to prepare a paste-like dielectric paste.

[0086] [Correction based on Rule 91 27.06.2023] [Peel Strength (mN / 50 mm)] The dielectric paste is applied to the surface of layer Y of the laminated film using the die coating method so that the dried thickness is 0.1 μm, and the paste is dried and solidified at 100°C for 60 seconds. A polyester adhesive tape (Nitto Denko Corporation No. 31B, width 19 mm) is attached to the surface of the dielectric paste laminated polyester, and the 180° peel strength is measured at a peel rate of 300 mm / min using Kyowa Interface Science Co., Ltd. VPA-H200, and converted to a 50 mm width. The peel strength is evaluated as follows according to the magnitude of the peel strength. Grade A is the best.

[0087] Evaluation A: 35 mN / 50 mm or less Evaluation B: More than 35 mN / 50 mm and 45 mN / 50 mm or less Evaluation C: More than 45 mN / 50 mm and 55 mN / 50 mm or less Evaluation D: More than 55 mN / 50 mm.

[0088] [Correction based on Rule 91, 27.06.2023] [Tear Frequency] A rectangular cut with a width of 50 mm and a length of 150 mm is made in a laminated polyester dielectric paste film, with the long side running in the longitudinal direction of the film. A polyester adhesive tape (Nitto Denko Corporation No. 31B, 19 mm wide) is attached to the center of one of the short sides of the cut, with the adhesive portion extending 10 mm in the longitudinal direction of the cut. The dielectric paste is then peeled off at an angle of 180° at a speed of 300 mm / min using a Kyowa Interface Science VPA-H200. The above measurement is performed 30 times, and the number of times the dielectric paste tears during peeling is used to make a rating as follows: Rating A is the best.

[0089] Rating A: Less than 5 times Rating B: 5 times or more but less than 10 times Rating C: 10 times or more but less than 15 times Rating D: More than 15 times.

[0090] [Evaluation] Peel strength and tear frequency were evaluated according to the above criteria, and the less favorable evaluation was adopted as the evaluation result. (IX-2) For adhesive transfer [Preparation of adhesive] 97 parts by mass of butyl acrylate, 3 parts by mass of acrylic acid, 0.2 parts by mass of azobisisobutyronitrile as a polymerization initiator, and 233 parts by mass of ethyl acetate were added, followed by a nitrogen gas flow and nitrogen substitution for approximately 1 hour while stirring. The flask was then heated to 60°C and reacted for 7 hours to obtain an acrylic polymer with a weight-average molecular weight (Mw) of 1,100,000. To this acrylic polymer solution (solid content: 100 parts by mass), 0.8 parts by mass of trimethylolpropane tolylene diisocyanate (trade name "Coronate" (registered trademark) L, manufactured by Nippon Polyurethane Industry Co., Ltd.) as an isocyanate crosslinking agent, and 0.1 parts by mass of a silane coupling agent (trade name "KBM-403", manufactured by Shin-Etsu Chemical Co., Ltd.) were added to prepare an adhesive composition.

[0091] [Correction based on Rule 91, 27.06.2023] [Peel Force (mN / 50 mm)] The adhesive is applied to the surface of Layer Y of a laminated polyester film using the die coating method to a dry thickness of 10 μm, and dried at 140°C for 60 seconds. A Toray Industries polyester film #50T60 is attached to the adhesive surface of the laminated polyester film, and the film is cut into a 19 mm wide, 300 mm long sample. The peel force at a 180° angle when peeling the laminated film from the sample is measured at a speed of 300 mm / min using a Kyowa Interface Science VPA-H200, and converted to a 50 mm width.

[0092] [Evaluation] Evaluation was made based on the peeling force as follows: Evaluation A is the best.

[0093] Rating A: 120 mN / 50 mm or less Rating B: More than 120 mN / 50 mm and 150 mN / 50 mm or less Rating C: More than 150 mN / 50 mm and 300 mN / 50 mm or less Rating D: More than 300 mN / 50 mm.

[0094] [Correction based on Rule 91, 27.06.2023] (X) Water Contact Angle of Resin Layer Y (HYp, HYa) A 10 cm square piece of laminated polyester film was cut, and the water contact angle of the surface on which layer Y was laminated was measured, designated as HYp. The cut laminated polyester film was then immersed in pure water at 25°C and stirred for 5 minutes. The laminated polyester film was then removed, the water on the surface was wiped off, and the water contact angle of the surface on which resin layer Y was laminated was measured, designated as HYa. The water contact angle was measured using a contact angle meter DM501 manufactured by Kyowa Interface Science Co., Ltd. and the accompanying analysis software FAMAS, measuring the angle of the water droplet 1 second after it landed on the laminated polyester film surface. The values ​​of HYa and |HYp - HYa| were measured, and the removability of resin layer Y was assessed.

[0095] (XI) Epoxy group content (mg / g) of resin layer X <Extraction conditions for resin layer X> A 0.5 m thick laminated polyester film was ２ After cutting and cutting, the material is placed in a flask with 80 ml of water and subjected to ultrasonic waves at a frequency of 40 kHz and an output of 360 W for 30 minutes to extract layer X. The resulting aqueous solution is filtered to remove impurities, and the solvent is then removed by freeze-drying to obtain a solid. <Analysis conditions> The resulting solid is extracted with heavy water and lyophilized under the following conditions. １ H NMR is measured. The epoxy groups are quantified based on the peak area derived from the epoxy groups. Apparatus: ECZ-600R (manufactured by JEOL RESONANCE Co., Ltd.) Measurement method: Single pulse Measurement frequency: 600.17 MHz Pulse width: 5.88 μs Chemical shift reference: TSP (sodium 3-trimethylsilylpropionate-2,2,3,3-d ４ ) (0 ppm) Number of accumulations: 16 Measurement temperature: 20°C Sample rotation speed: 15 Hz When acquiring the spectrum, a known amount of sodium 3-(trimethylsilyl)propionate (TSP) is added as an internal standard substance. From the spectrum obtained, the peak area Ea observed at 2.7 ppm, which is derived from the epoxy group, and the peak area Ta observed at 0 ppm, which is derived from the internal standard substance, are calculated. From the ratio of Ea to Ta and the amount of the added standard sample, the amount of epoxy groups corresponding to Ea is calculated and used as the amount of epoxy groups in layer X.

[0096] (XII) Amount of total organic components in the solid content of the resin layer X (mass %) <Conditions for extracting the resin layer X> A 0.5 m thick laminated polyester film was ２ After cutting and shredding, the resin is placed in a flask with 80 ml of water and subjected to ultrasonic cleaning at a frequency of 40 kHz and an output of 360 W for 30 minutes to extract layer X. The resulting aqueous solution is filtered to remove impurities, and the solvent is then removed by freeze-drying to obtain a solid. <Equivalent Mass of Resin Layer X> The thickness of resin layer X is measured using the above-mentioned method B, the volume of resin layer X is calculated, and this is then multiplied by the density 1.0, which is the density of the organic components. <Amount of Total Organic Components in Resin Layer X Solids> The mass of the solids obtained by the above-mentioned extraction method is measured and divided by the equivalent mass of resin layer X to calculate the percentage.

[0097] (XIII) Adhesion M(X) of Resin Layer X: In a film having a resin layer X, 5 square cm squares are cut with a weight of 10 g so that each square is 0.5 cm square. When a 31B tape manufactured by Nitto Denko Corporation is applied to the cut area and then peeled off, the number of squares in which the resin layer X has not migrated to the tape side is counted and expressed as a percentage.

[0098] The present invention will be described below with reference to examples, but the present invention is not necessarily limited to these examples.

[0099] [Production of PET-1] Terephthalic acid and ethylene glycol were polymerized in a conventional manner using antimony trioxide and magnesium acetate tetrahydrate as catalysts to obtain a melt-polymerized polyester. The resulting melt-polymerized polyester had a glass transition temperature of 81°C, a melting point of 255°C, an intrinsic viscosity of 0.65, and a terminal carboxyl group content of 20 eq. / t.

[0100] [Preparation of Coating Agent M] Coating Agent M was obtained by mixing 100 parts by mass of an addition reaction type silicone resin release agent (manufactured by Toray Dow Corning Silicone Co., Ltd., product name LTC750A) and 2 parts by mass of a platinum catalyst (manufactured by Toray Dow Corning Silicone Co., Ltd., product name SRX212) in toluene as a solvent to give a solids content of 5% by mass.

[0101] [Preparation of Coating Agent N] Polyvinyl alcohol "GL-05" (saponification degree 88, average polymerization degree 500) manufactured by Mitsubishi Chemical Corporation was dissolved in water to give a concentration of 4% by mass as PVA-1, to obtain Coating Agent N.

[0102] [Preparation of Coating Agent O] PVA-2 was prepared with a degree of saponification of 88, an average degree of polymerization of 400, and a copolymerization amount of sodium sulfonate of 1 mol% by referring to JP-A-9-227627. This PVA was dissolved in water to a concentration of 4% by mass, to obtain Coating Agent O.

[0103] [Preparation of Coating Agent P] PVA-3 was prepared with a degree of saponification of 88, an average degree of polymerization of 450, and a copolymerization amount of 1,2-ethanediol of 6 mol% by weight, with reference to JP 2004-285143 A. This PVA was dissolved in water to a concentration of 4% by mass, to obtain Coating Agent P.

[0104] [Coating Agent Q: Preparation of a Mixture Containing Compound B] 49 parts by mass of a 1% by mass aqueous solution of iron (III) sulfate, 8.8 parts by mass of the thiophene compound 3,4-ethylenedioxythiophene, and 117 parts by mass of a 10.9% by mass aqueous solution of peroxodisulfuric acid were added to 1,887 parts by mass of an aqueous solution containing 20.8 parts by mass of the acidic polymer compound polystyrene sulfonic acid. This mixture was stirred at 18 ° C. for 23 hours, and 154 parts by mass of a cation exchange resin ("Lebatit" (registered trademark) Monoplus S100H) and 232 parts by mass of an anion exchange resin ("Lebatit" (registered trademark) Monoplus M800) were added to this mixture. After stirring for 2 hours, the ion exchange resin was filtered off to obtain a mixture of poly(3,4-ethylenedioxythiophene) and polystyrene sulfonic acid (solids concentration 1.3% by mass), which was designated as Coating Agent Q.

[0105] [Correction based on Rule 91 27.06.2023] [Coating Agent R: Compound C (Epoxy Compound)] Coating Agent R was a polyglycerol polyglycidyl ether epoxy crosslinker ("Denacol" (registered trademark) EX-512 (molecular weight approximately 630, epoxy equivalent weight 168, water solubility 100%) manufactured by Nagase Chemtec Corporation.

[0106] [Preparation of Coating Agent S] PVA-4 was prepared with a degree of saponification of 88, an average degree of polymerization of 50, and a copolymerization amount of sodium sulfonate of 1 mol% by weight, with reference to JP-A-9-227627. This PVA was dissolved in water to a concentration of 4% by mass, to obtain Coating Agent S.

[0107] [Preparation of Coating Agent T] Coating Agent T was prepared by weighing out 10 parts by mass, converted into solids, of a long-chain alkyl group-containing polyvinyl resin ("Peeroil" (registered trademark) 1050, manufactured by Lion Specialty Chemicals Co., Ltd.) as a long-chain alkyl group-containing compound, 2.5 parts by mass, converted into solids, of a melamine-based crosslinking agent ("Sumimal" (registered trademark) M-55, manufactured by Sumitomo Chemical Co., Ltd.) as a crosslinking agent, and 1.3 parts by mass, converted into solids, of p-toluenesulfonic acid ("TAYCACURE" AC-700, manufactured by Teika Corporation) as an acid catalyst, and mixing these with 400 parts by mass of toluene and 130 parts by mass of methyl ethyl ketone as a solvent.

[0108] [Preparation of Coating Agent U] Coating agent U was an antistatic agent having a polystyrene sulfonic acid skeleton (antistatic agent "Fujistat" (registered trademark) YE908 manufactured by Fuji Chemical Co., Ltd.).

[0109] Example 1 PET-1 was vacuum dried at 160 ° C for 2 hours and then placed in an extruder, melted at 280 ° C, and extruded through a die onto a casting drum with a surface temperature of 25 ° C to produce an unstretched sheet. The sheet was then preheated with a group of heated rolls, stretched 3.3 times in the longitudinal direction (MD direction) at a temperature of 90 ° C, and then cooled with a group of rolls at a temperature of 25 ° C to obtain a uniaxially stretched polyester film. The resulting uniaxially stretched film was coated by a bar coating method with a coating prepared by mixing coating agent N and coating agent Q and diluting with pure water, so that the mass ratio of compound A to compound B was as shown in Table 1 and the thickness after drying was as shown in Table 1. Subsequently, while holding both ends of the film with clips, the film was stretched 4.0 times in the width direction (TD direction) perpendicular to the longitudinal direction in a heating zone at 100 ° C in a tenter. Subsequently, the film was heat-set for 10 seconds at a temperature of 230 ° C in a heat treatment zone in the tenter. The film was then uniformly cooled in a cooling zone and wound up to obtain a laminated polyester film having a resin layer X. The production conditions and properties of the obtained laminated polyester film are shown in Table 1.

[0110] The resin layer Y was coated to a thickness of 50 nm with coating agent M by gravure coating on the surface of the obtained laminated polyester film opposite to the surface of the resin layer X that was in contact with the polyester film, thereby obtaining a laminated polyester film. The properties of the obtained laminated polyester film are as shown in Table 2.

[0111] The results of using a polyester film laminated with resin layer Y as a process film are shown in Table 3. Since the mass ratio of compound A and compound B was the same, the Δ haze was slightly large, and as a result, the Ω of layer Y was （１５０） / Ω （０） In the green sheet molding application, oligomers were generated as foreign matter when heat was applied during the process, and the antistatic properties were slightly reduced. As a result, the molded green sheet was easily stuck to layer Y when peeled off, and the peel force and frequency of tearing were evaluated as being slightly inferior, but there were no practical problems. In the adhesive transfer application, the peel force F(B) of the resin layer Y surface after rubbing treatment with a solvent-impregnated cloth was slightly large, and the properties of layer Y were deteriorated due to the solvent used in applying the adhesive, and Ω （１５０）Although the peeling force of the adhesive was somewhat large and the antistatic property was poor, this was not a problem in practical use.

[0112]

[0113]

[0114]

[0115] Examples 2 to 10 Polyester films laminated with resin layer X and resin layer Y were obtained in the same manner as in Example 1, except that Coating Agent N, Coating Agent O, Coating Agent P, Coating Agent Q, and Coating Agent S were used as resin layer X so as to achieve the coating thickness, mass ratio of compound A and compound B, and types shown in Tables 1 and 4. The properties of the obtained laminated polyester films are shown in Tables 2 and 5, and the results of using the laminated polyester films as process films are shown in Tables 3 and 6.

[0116]

[0117]

[0118]

[0119] In Examples 2, 3, 7, 8 and 10, the Δ haze was small, and the Ω （１５０） / Ω （０） is in the preferred range, and the solvent durability rate F(A) / F(B) is also in the preferred range, so it has been found that excellent performance is exhibited for green sheet molding applications and adhesive transfer applications.

[0120] In Examples 4 and 9, the ratio of compound A was smaller than that of compound B, and as a result, the Δ haze was slightly larger, and the Ω （１５０） / Ω （０） In particular, in green sheet molding applications, oligomers were generated as foreign matter when heat was applied during the process, and the frequency of tearing when peeling off the molded green sheet was somewhat high, resulting in an inferior evaluation, but this was not a problem in practical use. In adhesive transfer applications, the solvent durability ratio F(A) / F(B) was somewhat large, and the properties of the resin layer Y were inferior due to the solvent used when applying the adhesive, so although the adhesive peel force was somewhat large, this was not a problem in practical use.

[0121] In Example 5, although the ratio of compound A was the same as that of compound B, the thickness of resin layer X was thin and the Δ haze was slightly large, resulting in a decrease in the Ω haze of layer Y. （１５０） / Ω （０） was slightly increased. In green sheet molding applications, oligomers were generated as foreign matter when heat was applied during the process, and antistatic properties were slightly reduced. As a result, the molded green sheet tended to stick to layer Y when peeling it off, and the peel strength and frequency of tearing were evaluated as being slightly inferior, but this did not pose a problem in practical use. In adhesive transfer applications, the peel strength F(B) of the resin layer Y surface after rubbing treatment with a solvent-impregnated cloth was slightly large, and since the properties of resin layer Y were inferior due to the solvent used in applying the adhesive, the peel strength of the adhesive was slightly large, but this did not pose a problem in practical use.

[0122] In Example 6, the release layer was thick, so Ω （０） and Omega （１５０） Although the characteristics were somewhat inferior for both green sheet molding and adhesive transfer, there were no problems in practical use.

[0123] Example 11 A polyester film laminated with resin layer X was obtained in the same manner as in Example 1, except that coating agent N and coating agent Q were used as resin layer X so as to have the coating thickness, mass ratio of compound A and compound B, and type as shown in Table 4. Coating agent T was applied by gravure coating to the surface of resin layer X of the obtained laminated polyester film opposite the surface that contacts the polyester film as resin layer Y to a thickness of 50 nm, thereby obtaining a laminated polyester film. The properties of the obtained laminated polyester film were as shown in Table 5.

[0124] The results of using a polyester film laminated with resin layer Y as a process film are shown in Table 6. Since a resin different from the resin mainly composed of a compound having a siloxane bond was used for layer Y, the surface free energy was slightly large and the Δ haze was also slightly large. （１５０） / Ω （０）In the green sheet molding application, oligomers were generated as foreign matter when heat was applied in the process, and the antistatic properties were slightly reduced. As a result, the molded green sheet tended to stick to layer Y when peeled off, and the peel force and frequency of tearing were evaluated as being slightly inferior, but this was not a problem in practical use. In the adhesive transfer application, the surface free energy was slightly high, and the peel force F(B) of the resin layer Y surface after rubbing treatment with a solvent-impregnated cloth was slightly high, and the properties of layer Y were deteriorated due to the solvent used in applying the adhesive, and Ω （１５０） Although the peeling force of the adhesive was somewhat large and the antistatic property was poor, this was not a problem in practical use.

[0125]

[0126]

[0127]

[0128] Examples 12, 13, and 15 Polyester films laminated with resin layer X and resin layer Y were obtained in the same manner as in Example 1, except that Coating Agent N, Coating Agent Q, and Coating Agent R were used as resin layer X so as to achieve the coating thickness, mass ratio, and types of Compound A, Compound B, and Compound C shown in Table 7. The properties of the obtained laminated polyester films are shown in Table 8, and the results of using the laminated polyester films as process films are shown in Table 9.

[0129] In Examples 12, 13, and 15, the compound C was used in the resin layer X, and therefore the removability of the resin layer X and the resin layer Y was good.

[0130] In Example 12, the Δ haze was small, and the Ω （１５０） / Ω （０） is in the preferred range, and the solvent durability rate F(A) / F(B) is also in the preferred range, so it has been found that excellent performance is exhibited for green sheet molding applications and adhesive transfer applications.

[0131] In Examples 13 and 15, the mass ratio of Compound C was slightly large, and the Δ haze increased slightly, but there was no practical problem for green sheet molding and adhesive transfer applications.

[0132] Example 14 A coating was prepared as resin layer X using coating N and coating Q so as to achieve the coating thickness, mass ratio of compound A and compound B, and type shown in the table. The coating was applied to a 50 μm-thick T60 (manufactured by Toray Industries, Inc.) to the thickness shown in the table, and dried at 150° C. to obtain a laminated polyester film having layer X. Layer Y was further laminated thereon in the same manner as in Example 1, to obtain a laminated polyester film having layer X and layer Y.

[0133] Since resin layer X was produced by offline coating, the coating had small defects, which resulted in a slightly high Δ haze and low adhesion. When a laminated polyester film having resin layer X and resin layer Y was evaluated as a process film, the results showed that although the Δ haze and other properties increased, there were no practical problems.

[0134] Comparative Example 1 A polyester film having resin layer X and resin layer Y laminated thereon was obtained in the same manner as in Example 1, except that only compound B was used as resin layer X and coating agent Q was used so as to achieve the coating thickness shown in Table 4. The properties of the obtained laminated polyester film are shown in Table 5, and the results of using the laminated polyester film as a process film are shown in Table 6.

[0135] Since compound A is not contained, Δ haze and Ω （１５０） / Ω （０） The solvent resistance ratio F(A) / F(B) was poor, and the film was not suitable for use as a processing film. It is believed that minute coating defects and microcracks occurred.

[0136] Comparative Example 2 A laminated polyester film having resin layer X and resin layer Y laminated thereon was obtained in the same manner as in Example 1, except that coating agent Q and coating agent R were used as resin layer X so as to achieve the mass ratio of compound B and compound B, and the coating thickness shown in Table 4. The properties of the obtained laminated polyester film are shown in Table 5, and the results of using the laminated polyester film as a process film are shown in Table 6.

[0137] Since compound A is not contained, Δ haze and Ω （１５０） / Ω （０）The solvent resistance ratio F(A) / F(B) was poor, and the film was not suitable for use as a processing film. It is believed that minute coating defects and microcracks occurred.

[0138] (Comparative Example 3) As components constituting the resin layer X, coating agent N was used as compound A, and coating agent U was used as a compound having antistatic properties, and a coating agent was prepared so that the solid content of compound A and the compound having antistatic properties were equal. A laminated polyester film having layer X and a laminated polyester film having layer X and layer Y were prepared in the same manner as in Example 1 except that this coating agent was used. Since compound B was not contained, Δ haze and Ω （１５０） / Ω （０） The film was inferior to the above and was not suitable for use as a process film.

[0139] The laminated polyester film of the present invention has excellent antistatic properties and heat resistance, and can be suitably used as a protective film for the pressure-sensitive adhesive layer in pressure-sensitive adhesive products or as a process film in the processing of various industrial products.

Claims

1. A laminated polyester film having a resin layer X containing at least a compound A having a vinyl alcohol residue, a compound B having a thiophene residue, and an epoxy compound C on at least one side of the polyester film.

2. 2. The laminated polyester film according to claim 1, wherein the epoxy group content in the solid content of the resin layer X determined from the laminated polyester film under specific extraction and analysis conditions is 5 mg / g or more and 100 mg / g or less.

3. 3. The laminated polyester film according to claim 1, wherein the total amount of organic components in the solid content of the resin layer X extracted under specific extraction conditions is 90% by mass or more, when the converted mass of the resin layer X of the laminated polyester film is 100% by mass.

4. 3. The laminated polyester film according to claim 1, wherein the total content of the compound A, the compound B, and the epoxy compound C is 90% by mass or more, based on 100% by mass of the resin layer X.

5. The laminated polyester film according to claim 1 or 2, wherein the proportion of the epoxy compound C in the total content of the compound A, the compound B, and the epoxy compound C in 100% by mass of the resin layer X is 16.7% by mass or more and 82.1% by mass or less.

6. 3. The laminated polyester film according to claim 1, wherein the degree of polymerization of the compound A is 50 or more and 1,000 or less.

7. The laminated polyester film according to claim 1 or 2, wherein the adhesiveness M(X) of the resin layer X satisfies the following condition: M(X)≧90(%)

8. 3. The method for producing a laminated polyester film according to claim 1, further comprising the steps of: applying the coating agent for forming the resin layer X to a polyester film; and stretching the polyester film in this order.

9. The laminated polyester film according to claim 1 or 2, comprising a polyester film, the resin layer X, and the resin layer Y in this order.

10. 10. The laminated polyester film according to claim 9, wherein the surface resistivity of the surface of the resin layer Y satisfies the following formulas (1) and (2): (1)10 ６ ≦Ω （０） ≦10 １０ (2) Oh （１５０） / Oh （０） <50 where Ω （０） : surface resistivity (Ω / sq) of the surface of the resin layer Y before heat treatment, Ω （１５０） : represents the surface resistivity (Ω / sq) of the surface of the resin layer Y after heat treatment at 150° C. for 60 minutes.

11. 10. The laminated polyester film according to claim 9, wherein the resin layer Y has a surface free energy of 30 mN / m or less.

12. 10. The laminated polyester film according to claim 9, wherein the resin layer Y is a resin containing a compound having a siloxane bond as a main component.

13. 10. The laminated polyester film according to claim 9, wherein the water contact angle on the Y-side of the resin layer satisfies the following formulas (3) and (4): (3) 0°≦HYa≦80° (4) 10°≦|HYp-HYa|≦100° Here, HYp represents the water contact angle on the Y surface side of the resin layer of the laminated polyester film, and HYa represents the water contact angle on the Y surface side of the resin layer of the laminated polyester film after the laminated polyester film is immersed in pure water at 25°C for 5 minutes.

14. 10. The laminated polyester film according to claim 9, which has a haze change of 10% or less after heat treatment at 150°C for 60 minutes.

15. The laminated polyester film according to claim 9, wherein the solvent resistance of the surface of the resin layer Y determined in accordance with JIS L 0849 (2013) (friction tester type II) is 50% or more and 100% or less.

16. The polyester film according to claim 9, which is used as a process film in a product manufacturing process.