Laminated film

Abstract

To provide a process film for manufacturing a ceramic green sheet in which the surface and the back face of a mold release layer have high smoothness and which is excellent in flaw defects and winding properties.SOLUTION: A laminated film having a release layer on one surface of a polyester film and satisfying the following requirements (1) to (3): (1) The polyester film and the release layer contain substantially no particles. (2) SaA is 0. 1nm or more and 6. 0nm or less, where SaA is an arithmetic average roughness of side A of the release layer. (3) SaB is 0. 5nm or more and less than 3. 0nm, where SaB is an arithmetic average roughness of a side B opposite to the side A.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a laminated film used as a processing film for producing ceramic green sheets. [Background technology]

[0002] Polyester films have excellent mechanical properties, electrical properties, dimensional stability, transparency, chemical resistance, etc., and are therefore widely used as substrate films in many applications, such as magnetic recording materials and packaging materials. In particular, they are suitably used as process paper for electronic components, release films for molding green sheets for multilayer ceramic capacitors, separators for liquid crystal polarizers, substrates for dry film resists, and substrates for releasing interlayer insulating resins.

[0003] In recent years, as multilayer ceramic capacitors have become smaller and their capacitance has increased, the thickness of ceramic sheets has also tended to decrease. Accordingly, release films used in the production of ultra-thin ceramic sheets have been required to have highly smooth release layer surfaces to prevent defects such as cissing and pinholes. For this reason, studies have been conducted on the use of release agents that do not contain silicone compounds, which cause cissing of ceramic slurries, as in Patent Document 1, and on improving the smoothness of release layer surfaces, as in Patent Document 2. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-152095 [Patent Document 2] Japanese Patent Application Publication No. 2023-39591 [Patent Document 3] Japanese Patent Application Laid-Open No. 2016-60158 Summary of the Invention [Problem to be solved by the invention]

[0005] However, even if the surface of the release layer is sufficiently smooth, if the back surface of the release film is poorly smooth, after a ceramic sheet is formed on the surface of the release layer and wound up, the back surface of the release film is transferred to the surface of the ceramic sheet, resulting in a decrease in smoothness.To address this issue, release films have been developed that impart high smoothness not only to the surface of the release layer but also to the back surface, as in Patent Document 3.However, if both sides of the release film are too smooth, handling deteriorates during the transport and winding processes when the film is manufactured and processed, so it has been difficult to achieve both high smoothness and handleability on both sides of the release film.

[0006] An object of the present invention is to provide a casting film for producing ceramic green sheets, which has a release layer with high smoothness on the front and back surfaces, and which is excellent in terms of scratch resistance and windability. [Means for solving the problem]

[0007] As a result of extensive research to achieve the above-mentioned objectives, the inventors discovered that by highly controlling the surface properties of both sides of the film, it is possible to provide a laminated film that has a release layer surface and back surface with high smoothness and that is easy to handle during the film manufacturing and processing processes, and thus completed the present invention.

[0008] That is, the present invention has the following configuration. [1] A laminated film having a release layer on one side of a polyester film and satisfying the following requirements (1) to (3): (1) The polyester film and the release layer are substantially free of particles. (2) When the surface of the release layer is designated as surface A and the arithmetic mean surface roughness of surface A is designated as SaA, SaA is 0.1 nm or more and 6.0 nm or less. (3) When the surface of the laminated film opposite to the surface A is surface B and the arithmetic mean surface roughness of surface B is SaB, SaB is 0.5 nm or more and less than 3.0 nm. [2] The laminate film according to [1], wherein the laminate film is substantially free of particles. [3] The laminated film according to [1] or [2], wherein the static friction coefficient μs between the A side and the B side is 0.3 or more and 0.8 or less. [4] The laminated film according to any one of [1] to [3], wherein the tape peel strength of the A-side is 0.1 N / 19 mm or more and 10 N / 19 mm or less. [5] The laminated film according to any one of [1] to [4], wherein SpB is the maximum projection height of the surface B, and SpB is less than 60 nm. [6] A laminated film described in any one of [1] to [5], wherein when the surface of the release layer is analyzed by time-of-flight secondary ion mass spectrometry, the ratio (P / K)[-] of the peak intensity (P) of the fragment derived from polydimethylsiloxane to the peak intensity (K) of the fragment detected at maximum intensity is less than 0.01. [7] The laminated film according to any one of [1] to [6], which does not contain perfluoroalkyl compounds and polyfluoroalkyl compounds (PFAS). [8] The laminated film according to any one of [1] to [7], wherein the surface layer of the side B has a lubricious layer. [9] The laminated film according to any one of [1] to [8], which is used as a process film for producing a ceramic green sheet. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a laminated film to be used as a process film for producing ceramic green sheets, which suppresses defects in the ceramic sheet due to unevenness on the surface of the release layer and backside transfer to the ceramic sheet surface, and has excellent resistance to scratches and defects during the film production and processing process and excellent winding properties. DETAILED DESCRIPTION OF THE INVENTION

[0010] DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a laminated film having a release layer on one side of a polyester film, which satisfies the following requirements (1) to (3). (1) The polyester film and the release layer are substantially free of particles. (2) When the surface of the release layer is designated as surface A and the arithmetic mean surface roughness of surface A is designated as SaA, SaA is 0.1 nm or more and 6.0 nm or less. (3) When the surface of the laminated film opposite to the surface A is surface B and the arithmetic mean surface roughness of surface B is SaB, SaB is 0.5 nm or more and less than 3.0 nm.

[0011] In the present invention, in order to adjust the surface of the laminated film to a predetermined roughness range, it is preferable that the polyester film and the release layer are substantially free of particles. More preferably, the laminated film is substantially free of particles. By making the polyester film and the release layer substantially free of particles, the surface roughness of sides A and B can be set within a preferred range.

[0012] In the laminate film of the present invention, the arithmetic mean roughness SaA of the A-side is preferably 0.1 nm to 6.0 nm, more preferably 0.1 nm to 4.0 nm, and even more preferably 0.1 nm to 2.0 nm. The arithmetic mean roughness is determined by measurement using a scanning white light interference microscope (Vertscan), and detailed measurement methods are described in the Examples. SaA can be controlled by the resin composition of the polyester film and the composition of the release layer. If the arithmetic mean roughness SaA of the A-side is greater than 6.0 nm, the unevenness of the release layer surface is likely to cause defects such as pinholes and thickness unevenness in the ceramic sheet. If the arithmetic mean roughness SaA is less than 0.1 nm, the smooth surface of the release layer increases the contact area with other surfaces, resulting in poor winding properties and concerns about reduced quality due to static electricity and scratches on the film.

[0013] In the laminate film of the present invention, the arithmetic mean roughness SaB of the B side is preferably 0.5 nm or more and less than 3.0 nm. It is more preferably 0.5 nm or more and 2.0 nm or less, and even more preferably 0.5 nm or more and 1.0 nm or less. SaB can be controlled by the resin composition of the polyester film and the manufacturing method of the B side, including surface treatment. If the arithmetic mean roughness SaB of the B side is 3.0 nm or more, after forming a ceramic sheet on the A side and winding it, the unevenness of the B side will be transferred to the ceramic sheet surface, reducing smoothness. If the arithmetic mean roughness SaB is less than 0.5 nm, there is a concern that winding properties will be impaired and quality will be reduced due to static electricity or scratches on the film.

[0014] The laminate film of the present invention preferably has a tape peel strength of 0.1 N / 19 mm to 10 N / 19 mm, more preferably 0.5 N / 19 mm to 6.0 N / 19 mm, and even more preferably 0.5 N / 19 mm to 2.0 N / 19 mm, as measured by the method described below. The tape peel strength can be controlled by the components of the release layer. A tape peel strength of 10 N / 19 mm or less prevents damage and defects when peeling off a mating component, for example, when used in a processing film for manufacturing electronic components, particularly a hydrophilic resin layer such as an epoxy resin that forms an interlayer insulating film when used as a release processing film for an interlayer insulating film in the process of manufacturing wiring boards, or a ceramic green sheet when used as a support film for green sheet molding in the process of manufacturing multilayer ceramic capacitors. A tape peel strength of 0.1 N / 19 mm or more prevents the mating component from accidentally lifting off from the A-side during transport.

[0015] The static friction coefficient μs between the A side and the B side of the laminate film of the present invention, as measured by the measurement method described below, is preferably 0.3 to 0.8, more preferably 0.4 to 0.7. The static friction coefficient μs can be controlled by the surface shape of the A side and the B side, the manufacturing method, etc. By setting the static friction coefficient μs to 0.8 or less, the transportability is improved and the occurrence of scratches during transport of the film can be suppressed. By setting the static friction coefficient μs to 0.3 or more, the laminate film is less likely to slip when wound up.

[0016] In the laminate film of the present invention, when the maximum protrusion height SpB is defined as the maximum protrusion height SpB on the B side, SpB is preferably less than 60 nm. It is more preferably 40 nm or less. SpB can be controlled by the resin composition of the polyester film and the composition of the release layer. By controlling the maximum protrusion height SpB to be less than 60 nm, it is possible to prevent the irregularities on the B side from being transferred to the ceramic sheet surface, thereby reducing smoothness. When the release layer of the laminate film of the present invention is analyzed by time-of-flight secondary ion mass spectrometry, it is preferable that the ratio (P / K)[-] of the peak intensity (P) of the fragment derived from polydimethylsiloxane to the peak intensity (K) of the fragment detected at the maximum intensity is less than 0.01. As will be described later, when the peak intensity ratio (P / K) is less than 0.01, the release layer contains fewer components derived from polydimethylsiloxane. Therefore, when the laminate film of the present invention is used as a process film for manufacturing electronic components, problems such as poor conductivity, poor insulation, and pinhole defects due to the migration of silicone compounds (particularly polydimethylsiloxane) to the product can be prevented.

[0017] The laminated film of the present invention preferably does not contain perfluoroalkyl compounds and polyfluoroalkyl compounds (PFAS). PFAS are highly stable but persistent, so not containing PFAS can reduce the environmental impact.

[0018] The laminated film of the present invention may have a lubricity layer on side B. By having the lubricity layer, the surface properties of side B can be adjusted within a preferred range.

[0019] The laminated film of the present invention will be described in detail below.

[0020] <Polyester film> The polyester film of the present invention is a film containing a polyester resin as a main component. Here, in the present invention, "main component" means that the proportion of the polyester resin in the polyester film is 50% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and most preferably 99% by mass or more.

[0021] The polyester resin of the present invention is a polyester obtained by polymerization of a monomer or oligomer having as main components a dicarboxylic acid, a diol, and an ester-forming derivative thereof.

[0022] The dicarboxylic acid is preferably an aromatic dicarboxylic acid. Examples of aromatic dicarboxylic acids include terephthalic acid and 2,6-naphthalenedicarboxylic acid, with terephthalic acid being preferred. These acid components may be used alone or in combination of two or more, and may be partially copolymerized with other aromatic dicarboxylic acids such as isophthalic acid or fatty acids.

[0023] Examples of the diol component include fatty acid 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 cyclohexanediol and spiroglycol, and diols in which two or more of the above diols are linked together, with ethylene glycol being preferred. These diol components may be used alone or in combination.

[0024] From the viewpoints of mechanical properties and transparency, preferred polyester resins include polyethylene terephthalate, polyethylene naphthalate, and copolymers thereof, polybutylene terephthalate and copolymers thereof, polybutylene naphthalate and copolymers thereof, polyhexamethylene terephthalate and copolymers thereof, polyhexamethylene naphthalate and copolymers thereof, and the like, with polyethylene terephthalate being particularly preferred.

[0025] The polyester used in the present invention can be produced by a conventionally known method. For example, a method can be used in which an acid component is directly esterified with a diol component, followed by polycondensation while heating the reaction product under reduced pressure to remove excess diol component. Alternatively, a method can be used in which a dialkyl ester is used as the acid component, and the acid component is transesterified with the diol component, followed by polycondensation in the same manner as above. If necessary, conventionally known alkali metals, alkaline earth metals, manganese, cobalt, zinc, antimony, germanium, titanium compounds, etc. can be used as a reaction catalyst. If necessary, the polyester obtained by melt polymerization can be subjected to solid-state polymerization at a temperature below the melting point of the polyester.

[0026] The polyester film in the laminate film of the present invention is preferably biaxially oriented. Biaxially oriented polyester films can be obtained by melt-extruding the above-mentioned raw materials into a sheet and then biaxially stretching the sheet. Biaxial orientation improves the mechanical strength and lubricity of the film. Biaxial orientation here refers to a film that exhibits a biaxially oriented pattern in wide-angle X-ray diffraction. Biaxially oriented polyester films can generally be obtained by biaxially stretching an unstretched polyester resin sheet in the longitudinal and transverse directions of the sheet, followed by heat treatment to complete the crystal orientation. Biaxial stretching can be achieved by any of the following methods: inflation, simultaneous biaxial stretching, and sequential biaxial stretching. Among these, sequential biaxial stretching is preferred in terms of film formation stability, thickness uniformity, and controlling the high rigidity and dimensional stability of the film.

[0027] In the biaxially oriented polyester film, the layer having a release layer on its surface and the layer having the aforementioned side B may be the same layer, or may have a two-layer structure consisting of a layer having side A and a layer having side B, or a three-layer structure with an intermediate layer between the layer having side A and the layer having side B. The biaxially oriented polyester film may contain additives such as heat stabilizers, oxidation stabilizers, antistatic agents, nucleating agents, dyes, dispersants, coupling agents, and wavelength converting materials, as long as the effects of the present invention are not impaired. However, in order to achieve the surface roughness of sides A and B within the above-mentioned ranges, it is preferable that the film does not contain particles. The thickness of the polyester film is not particularly limited and can be selected appropriately depending on the application and type. However, from the viewpoints of mechanical strength, handleability, and prevention of wrinkles during winding, it is usually preferably 10 to 500 μm, more preferably 15 to 125 μm, and most preferably 30 to 75 μm.

[0028] <Release layer (layer with side A)> The release layer in the laminate film of the present invention is provided on one side of the polyester film, and is preferably provided on one surface layer of the laminate film. This layer is necessary for easy peeling in the step of peeling a surface layer such as an adhesive tape or an epoxy resin from the laminate film after laminating the surface layer on the release layer of the laminate film of the present invention.

[0029] <Components of the release layer> Preferred components for forming the release layer of the laminated film of the present invention will now be described.

[0030] The release layer of the laminated film of the present invention is preferably formed from a coating composition containing a release agent (A) and at least one resin or compound (B) selected from epoxy resins, melamine resins, oxazoline compounds, carbodiimide compounds, polyester resins, acrylic resins, and urethane resins. This configuration makes it easy to provide a release layer with a tape peel strength of 0.1 N / 19 mm or more and 2.0 N / 19 mm or less, which can provide good releasability from mating members when used as a processing film for the production of electronic components.

[0031] <Release agent (A)> The release agent (A) in this invention refers to a compound that, when contained in a coating composition, imparts releasability to the surface of the coating layer (i.e., the property of reducing the surface free energy of the resin or reducing the static friction coefficient μs of the resin). Examples of the release agent (A) that can be used in this invention include long-chain alkyl group-containing resins, olefin resins, fluorine compounds, wax-based compounds, etc. Among these, long-chain alkyl group-containing resins are preferred because they can impart good releasability.

[0032] Commercially available long-chain alkyl group-containing compounds may be used. Specific examples include the "Ashio Resin" (registered trademark) series of long-chain alkyl compounds manufactured by Asio Sangyo Co., Ltd., the "Peiroil" (registered trademark) series of long-chain alkyl compounds manufactured by Lion Specialty Chemicals Co., Ltd., and the "Rezem" series of aqueous dispersions of long-chain alkyl compounds manufactured by Chukyo Yushi Co., Ltd. The release agent (A) preferably has an alkyl group having 12 or more carbon atoms, and more preferably an alkyl group having 16 or more carbon atoms. By increasing the carbon number of the alkyl group to 12 or more, hydrophobicity is enhanced, allowing the release agent (A) to exhibit sufficient release performance. If the alkyl group has fewer than 12 carbon atoms, release performance may be insufficient. While there is no particular upper limit on the number of carbon atoms in the alkyl group, a carbon number of 25 or less is preferred for ease of production.

[0033] The resin having an alkyl group having 12 or more carbon atoms is more preferably a resin having a side chain of an alkyl group having 12 or more carbon atoms on a polymethylene main chain. When the main chain is polymethylene, the number of hydrophilic groups in the entire resin is reduced, and the release effect of the release agent (A) can be improved.

[0034] The presence or absence of alkyl groups with 12 carbon atoms can also be evaluated from the laminate film, for example, based on the peak intensity corresponding to the alkyl group among the signals obtained by TOF-SIMS (TOF-SIMS: time-of-flight secondary ion mass spectrometry). In this case, by combining it with a cutting method using ion sputtering, it is possible to perform continuous measurements in the depth direction, and the distribution of alkyl group-containing compounds can also be evaluated.

[0035] <Resin or Compound (B)> Examples of the resin or compound (B) that can be used in the release layer of the present invention include epoxy resins, melamine resins, oxazoline compounds, carbodiimide compounds, polyester resins, acrylic resins, urethane resins, etc. Among these, melamine resins and acrylic resins are preferred because they make it easy to control the interaction due to hydroxyl groups and the release layer is easily changed by high-temperature heating.

[0036] Examples of epoxy resins that can be used as resin or compound (B) include sorbitol polyglycidyl ether-based crosslinkers, polyglycerol polyglycidyl ether-based crosslinkers, diglycerol polyglycidyl ether-based crosslinkers, and polyethylene glycol diglycidyl ether-based crosslinkers. Commercially available epoxy resins may be used, such as the epoxy compounds "Denacol" (registered trademark) manufactured by Nagase Chemtec Corporation (EX-611, EX-614, EX-614B, EX-512, EX-521, EX-421, EX-313, EX-810, EX-830, EX-850, etc.), diepoxy / polyepoxy compounds manufactured by Sakamoto Pharmaceutical Co., Ltd. (SR-EG, SR-8EG, SR-GLG, etc.), and epoxy crosslinkers "EPICLON" (registered trademark) EM-85-75W and CR-5L manufactured by Dainippon Ink Mfg. Co., Ltd., among others. Among these, water-soluble epoxy resins are preferred.

[0037] Examples of melamine resins that can be used as resin or compound (B) include melamine, methylolated melamine derivatives obtained by condensing melamine with formaldehyde, compounds obtained by reacting methylolated melamine with a lower alcohol to partially or completely etherify the melamine, and mixtures thereof. Furthermore, the melamine resin may be a condensate of a monomer or a dimer or higher polymer, or a mixture thereof. Examples of lower alcohols that can be used for etherification include methyl alcohol, ethyl alcohol, isopropyl alcohol, n-butanol, and isobutanol. Examples of functional groups that can be used include imino, methylol, or alkoxymethyl groups such as methoxymethyl and butoxymethyl groups per molecule, such as imino-type methylated melamine resins, methylol-type methylated melamine resins, methylol-type methylated melamine resins, and fully alkylated methylated melamine resins. Among these, methylolated melamine resins are the most preferred.

[0038] Furthermore, the oxazoline compound that can be used as the resin or compound (B) has an oxazoline group as a functional group in the compound, and is preferably an oxazoline group-containing copolymer obtained by copolymerizing at least one monomer containing an oxazoline group and at least one other monomer.

[0039] Examples of monomers containing 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-methyl-2-oxazoline, and 2-isopropenyl-5-ethyl-2-oxazoline, and these may be used alone or in combination. Of these, 2-isopropenyl-2-oxazoline is preferred because it is easily available industrially.

[0040] In the oxazoline compound, at least one other monomer used for the monomer containing an oxazoline group is a monomer copolymerizable with the monomer containing an oxazoline group, and examples thereof include acrylic acid esters or methacrylic acid esters such as methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate, and 2-ethylhexyl methacrylate; unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, and maleic acid; acrylonitrile; and methacrylonitrile. Any unsaturated nitriles, unsaturated amides such as acrylamide, methacrylamide, N-methylolacrylamide, N-methylolmethacrylamide, vinyl esters such as vinyl acetate and vinyl propionate, vinyl ethers such as methyl vinyl ether and ethyl vinyl ether, olefins such as ethylene and propylene, halogen-containing α,β-unsaturated monomers such as vinyl chloride, vinylidene chloride, and vinyl fluoride, and α,β-unsaturated aromatic monomers such as styrene and α-methylstyrene, and the like can be used alone or in combination of two or more thereof.

[0041] The carbodiimide compound usable as the resin or compound (B) is a compound having one or more carbodiimide groups or tautomeric cyanamide groups as functional groups in the molecule. Specific examples of such carbodiimide compounds include dicyclohexylmethanecarbodiimide, dicyclohexylcarbodiimide, tetramethylxylylenecarbodiimide, and urea-modified carbodiimide, and these can be used alone or in combination.

[0042] The polyester resin that can be used as the resin or compound (B) preferably has an ester bond in the main chain or side chain and is obtained by polycondensation of a dicarboxylic acid and a diol.

[0043] The dicarboxylic acid raw material for the polyester resin can be aromatic, aliphatic, or alicyclic. Examples of aromatic dicarboxylic acids include terephthalic acid, isophthalic acid, orthophthalic acid, phthalic acid, 2,5-dimethylterephthalic acid, 1,4-naphthalenedicarboxylic acid, biphenyldicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,2-bisphenoxyethane-p-p'-dicarboxylic acid, and phenylindanedicarboxylic acid. Examples of aliphatic and alicyclic dicarboxylic acids include succinic acid, adipic acid, sebacic acid, azelaic acid, dodecanedioic acid, dimer acid, 1,3-cyclopentanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, and 1,4-cyclohexanedicarboxylic acid, as well as their ester-forming derivatives.

[0044] Examples of diol components that can be used as raw materials for the polyester resin include ethylene glycol, diethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 2,4-dimethyl-2-ethylhexane-1,3-diol, neopentyl glycol, 2-ethyl-2-butyl-1,3-propanediol, 2-ethyl-2-isobutyl-1,3-propanediol, 3-methyl-1,5-pentanediol, and 2,2,4-trimethyl- 1,6-hexanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, 4,4'-thiodiphenol, bisphenol A, 4,4'-methylenediphenol, 4,4'-(2-norbornylidene)diphenol, 4,4'-dihydroxybiphenol, o-, m-, and p-dihydroxybenzene, 4,4'-isopropylidenephenol, 4,4'-isopropylidenebindiol, cyclopentane-1,2-diol, cyclohexane-1,2'-diol, cyclohexane-1,2-diol, cyclohexane-1,4-diol, and the like can be used.

[0045] Furthermore, modified polyester copolymers, such as block copolymers and graft copolymers modified with acrylic, urethane, epoxy, etc., can also be used as the polyester resin.

[0046] The acrylic resin that can be used as the resin or compound (B) is not particularly limited, but is preferably composed of alkyl methacrylate and / or alkyl acrylate.

[0047] The alkyl methacrylate and / or alkyl acrylate preferably includes methacrylic acid, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-hexyl methacrylate, lauryl methacrylate, 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate, acrylic acid, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, n-hexyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, hydroxypropyl acrylate, maleic acid, itaconic acid, acrylamide, N-methylolacrylamide, diacetone acrylamide, etc. These may be used alone or in combination of two or more.

[0048] Furthermore, the urethane resin that can be used as the resin or compound (B) is preferably a resin obtained by reacting a polyhydroxy compound with a polyisocyanate compound by a known urethane resin polymerization method such as emulsion polymerization or suspension polymerization.

[0049] Examples of polyhydroxy compounds include polyethylene glycol, polypropylene glycol, polyethylene propylene glycol, polytetramethylene glycol, hexamethylene glycol, tetramethylene glycol, 1,5-pentanediol, diethylene glycol, triethylene glycol, polycaprolactone, polyhexamethylene adipate, polyhexamethylene sebacate, polytetramethylene adipate, polytetramethylene sebacate, trimethylolpropane, trimethylolethane, pentaerythritol, polycarbonate diol, and glycerin.

[0050] Examples of polyisocyanate compounds that can be used include hexamethylene diisocyanate, diphenylmethane diisocyanate, tolylene diisocyanate, isophorone diisocyanate, an adduct of tolylene diisocyanate and trimethylenepropane, and an adduct of hexamethylene diisocyanate and trimethylolethane.

[0051] Furthermore, the release layer of the laminated film of the present invention may contain an isocyanate compound as the resin or compound (B). Examples of the isocyanate compound include tolylene diisocyanate, diphenylmethane-4,4'-diisocyanate, meta-xylylene diisocyanate, hexamethylene-1,6-diisocyanate, 1,6-diisocyanatehexane, an adduct of tolylene diisocyanate and hexanetriol, an adduct of tolylene diisocyanate and trimethylolpropane, polyol-modified diphenylmethane-4,4'-diisocyanate, carbodiimide-modified diphenylmethane-4,4'-diisocyanate, isophorone diisocyanate, 1,5-naphthalene diisocyanate, 3,3'-bitrylene-4,4'-diisocyanate, 3,3'-dimethyldiphenylmethane-4,4'-diisocyanate, and meta-phenylene diisocyanate.

[0052] Furthermore, since isocyanate groups readily react with water, in terms of the pot life of the coating composition, it is preferable to use blocked isocyanate compounds in which the isocyanate groups are masked with a blocking agent, etc. In this case, when heat is applied in the drying process after the coating composition is applied to the polyester film, the blocking agent dissociates, exposing the isocyanate groups and causing the crosslinking reaction to proceed.

[0053] In the coating composition forming the release layer of the laminated film of the present invention, it is preferable that the mass ratio of the release agent (A) to the resin or compound (B) is in the range of 10 / 90 to 70 / 30. More preferably, it is in the range of 15 / 85 to 65 / 35. By setting the ratio within such a range, a sufficient amount of the release agent (A) in the release layer can be obtained, and the initial tape peeling force and the peeling force from the surface layer after low-temperature heating can be made good. At the same time, since the resin or compound (B) that is likely to change by heating also becomes a sufficient amount, the peeling characteristics before and after heating can be made good.

[0054] From the viewpoint of controlling the arithmetic mean roughness SaA of the A surface within a preferable range, it is preferable that the coating composition forming the release layer of the laminated film of the present invention does not contain a particulate component.

[0055] The method for forming the release layer in the present invention is not particularly limited, but when using the above coating composition components, it is preferable to use either an off-coat method in which coating is performed after the production of the polyester film or an in-line coating method in which coating and drying are performed during the production process of the polyester film. Particularly in the production process of a biaxially stretched polyester film, it is most preferable, from the viewpoint of making the surface smoother by stretching the coating composition uniformly by stretching to form a release layer, to perform in-line coating on the polyester film after longitudinal stretching and then dry the coating composition in the subsequent transverse stretching step.

[0056] <Layer having a B surface> In the layer having a B surface in the laminated film of the present invention, it is preferable to use a polyester resin, an acrylic resin, an epoxy resin, a melamine resin, or a urethane resin as the main component.

[0057] As a method for controlling the arithmetic mean roughness SaB and the maximum protrusion height SpB of the B surface in the present invention within a preferable range, forming a lubricious layer on the polyester film can be mentioned.

[0058] When a lubrication layer is formed on a polyester film, it is preferable that the lubrication layer contains at least a binder resin. The lubrication layer may contain inorganic and organic particles in the coating composition as long as the effects of the present invention are not impaired. However, in order to keep the arithmetic surface roughness SaB and maximum protrusion height SpB of side B within the above-mentioned ranges, it is preferable that the particle content of the coating composition be 0.1% or less, and more preferably that the coating composition contains no particles.

[0059] The method for forming the lubrication layer in the present invention is not particularly limited, but when the above-mentioned coating composition is used, it is preferable to use either an off-coating method in which coating is performed after polyester film production or an in-line coating method in which coating and drying are performed during the polyester film production process. In particular, in the process for producing biaxially stretched polyester films, it is preferable to apply in-line coating to the polyester film after longitudinal stretching and then dry the coating composition during the transverse stretching process from the viewpoint of handleability and winding shape in the polyester film production process.

[0060] <Laminated film manufacturing method> Next, the method for producing the laminated film of the present invention will be explained using a biaxially oriented polyester film as an example, but is not necessarily limited thereto. The method for producing the biaxially oriented polyester film of the present invention comprises the following two steps. (a) Polyester resin is molded into a sheet by melt casting. (b) The obtained sheet is stretched by a roll method or a tenter method. Each step will be described below.

[0061] (a) Sheet formation by melt-casting polyester resin One or more polyester resins are mixed in a predetermined ratio as needed, dried, and then fed to an extruder where they are heated and melted. A single-screw or twin-screw extruder can be used as the extruder for producing the biaxially oriented polyester film of the present invention. A vented extruder equipped with a vacuum line can also be used to eliminate the pellet drying process. When an intermediate layer is provided, the extrusion volume is the highest, so a so-called tandem extruder can be used, in which the function of melting the pellets and the function of maintaining the molten pellets at a constant temperature are shared between the extruders.

[0062] The polymer melted and extruded in the extruder is filtered through a filter. Because even the smallest foreign particles can cause large protrusion defects in the film, it is effective to use a high-precision filter capable of removing 95% or more of foreign particles, for example, 5 μm or larger. The molten polymer is then guided into a slit die and extruded from the die onto a cooled casting drum to form a sheet (melt casting method). When producing a laminated polyester film with two or more layers by the melt casting method, a preferred method is to use an extruder for each layer constituting the laminated polyester film, melt the raw materials for each layer, laminate them in the molten state in a confluence device installed between the extrusion device and the die, then guide them into the die and extrude them through the die onto a casting drum to form a sheet (co-extrusion method). The laminated sheet is then cooled and solidified by static electricity on a drum cooled to a surface temperature of 20°C to 60°C, producing an unstretched sheet. The temperature of the casting drum is preferably 25°C to 60°C, and even more preferably 30°C to 55°C. If the temperature is below 20°C, the formation of protrusions on the film surface after biaxial stretching may be insufficient when the film is subjected to the plasma treatment described below.If the temperature exceeds 60°C, the film may stick to the casting drum, making it difficult to obtain an unstretched sheet.

[0063] (b) Stretching process The resulting laminate sheet is biaxially stretched while simultaneously applying the coating composition by in-line coating and drying to provide a release layer and, in some cases, a lubrication layer. Examples of stretching methods include simultaneous biaxial stretching using a simultaneous biaxial tenter, sequential biaxial stretching using a roll stretcher and tenter, or a combination of a tenter and tenter. When using the simultaneous biaxial stretching method, the coating composition is applied to one or both sides of an unstretched film and dried while stretching to provide a release layer and a lubrication layer. When using the sequential biaxial stretching method, in which the film is first stretched in the longitudinal direction and then stretched in the width direction, the coating composition is applied to one or both sides of the film after stretching in the longitudinal direction, and then stretched in the width direction and dried to provide a release layer and a lubrication layer. From the perspective of further improving adhesion between the polyester film and the release layer and the lubrication layer, it is preferable to provide a release layer and a lubrication layer by in-line coating after longitudinal stretching in sequential biaxial stretching.

[0064] In the case of sequential stretching, the initial longitudinal stretching is performed by the difference in peripheral speed of the rolls, and the stretching temperature is preferably 90°C or higher but lower than 130°C, more preferably 100°C or higher but lower than 125°C. A stretching temperature lower than 90°C is prone to film breakage, while a stretching temperature higher than 130°C is undesirable because the film surface is susceptible to thermal damage. Furthermore, to prevent uneven stretching and scratches, stretching is preferably performed in two or more stages, with a total stretching ratio of preferably 3x or higher but lower than 5x, more preferably 3.5x or higher but lower than 4.5x. A longitudinal stretching ratio of 3x or higher promotes orientation crystallization, improving film strength. On the other hand, a stretching ratio of 5x or lower can prevent excessive orientation crystallization of the polyester resin during stretching, resulting in brittleness or tearing during film formation. The stretching ratio can be selected appropriately to achieve the target film breaking strength. If the temperature and magnification are outside the above ranges, problems such as uneven stretching or film breakage will occur, making it difficult to obtain the film that is characteristic of the present invention, and this is not preferred. After stretching, the rolls are preferably cooled with a group of rolls having a temperature of 20 to 50°C.

[0065] Subsequently, for stretching in the direction perpendicular to the longitudinal direction (width direction), the film is introduced into a tenter while holding both edges with clips, and stretched 3 to 5 times in the direction perpendicular to the longitudinal direction (width direction) in an atmosphere heated to a temperature of 70 to 160°C. At this time, the film stretched in the width direction may be subjected to a cooling treatment in which the film is cooled stepwise to a film temperature of 80 to 100°C in the first stage and 20 to 55°C in the second stage. Examples of cooling methods for polyester films include air-cooling using a tenter where heat treatment is performed, air-cooling using shielding plates such as aluminum plates above and below the heat treatment area to block hot air, and cooling using rolls. The cooling treatment is preferable because it prevents excessive crystal growth in the subsequent heat treatment step and promotes uniform protrusion formation.

[0066] The stretched film is then preferably heat-treated to stabilize the internal orientation structure. The heat treatment is preferably performed at a maximum temperature in the tenter of 200°C to 250°C for a heat treatment time of 0.5 seconds to less than 20 seconds. A heat treatment temperature of 200°C or higher allows the protrusions formed by the atmospheric pressure glow discharge treatment to grow sufficiently, resulting in the formation of protrusions within a preferred range. On the other hand, heat treatment at 250°C or lower can prevent a decrease in film strength and frequent tearing, thereby improving productivity. From the same perspective, a more preferred range is 220°C to 245°C. Furthermore, while local temperature changes within the tenter tend to cause uneven protrusion formation, extending the heat treatment time can promote sufficient protrusion growth and mitigate the effects of local temperature changes. Therefore, a heat treatment time of 0.5 seconds or longer is preferred, more preferably 2 seconds or longer. A heat treatment time of 20 seconds or shorter can prevent a decrease in film strength and frequent tearing, thereby improving productivity, and is more preferably 12 seconds or shorter. Furthermore, after the heat treatment, relaxation treatment may be carried out in the range of 0% to 6% in order to impart dimensional stability.

[0067] The stretching ratio is 3 to 5 times in both the longitudinal and transverse directions, and the area ratio (longitudinal stretching ratio x transverse stretching ratio) is preferably 9 to 22 times, more preferably 9 to 20 times. When the area ratio is 9 times or more, the durability of the resulting biaxially oriented sheet can be improved, and when the area ratio is 22 times or less, the occurrence of tearing during stretching can be reduced.

[0068] The biaxially stretched film thus obtained is cooled in a conveying process, and then the edges are cut and wound up. If necessary, the film is slit into an appropriate width and length in a slitting process and wound up to obtain a laminated film roll of the present invention.

[0069] <Inline court> In the present invention, it is preferable to form a release layer by applying a coating composition to at least one surface of a polyester film and then drying the coating composition.

[0070] The coating composition can be applied to the laminated polyester film of the present invention by any known coating method, such as wire bar coating, reverse coating, gravure coating, die coating, blade coating, dip coating, air knife coating, curtain coating, and roller coating.

[0071] In the present invention, when a solvent is contained in the coating composition, it is preferable to use an aqueous solvent as the solvent. By using an aqueous solvent, it is possible to suppress rapid evaporation of the solvent during the drying step, and not only can a uniform release layer be formed, but also it is excellent in terms of environmental load.

[0072] Here, the aqueous solvent refers to water or a mixture of water and a water-soluble organic solvent, such as an alcohol such as methanol, ethanol, isopropyl alcohol, or butanol, a ketone such as acetone or methyl ethyl ketone, or a glycol such as ethylene glycol, diethylene glycol, or propylene glycol, in any ratio.

[0073] Furthermore, the solid content of the coating composition is preferably 40% by mass or less. By setting the solid content to 40% by mass or less, the coating composition can be given good coatability, and a laminated film having a uniform release layer can be produced.

[0074] The solid content concentration represents the proportion of the mass of the coating composition obtained by subtracting the mass of the solvent from the mass of the coating composition (i.e., [solid content concentration (mass %)] = [(mass of coating composition) - (mass of solvent)] / [mass of coating composition] × 100).

[0075] In the width direction stretching step of the laminated polyester film manufacturing process of the present invention, stretching at a temperature in the range of 70°C to 160°C as described above allows the coating composition to be dried, the solvent to be completely removed, and a uniform release layer to be formed. Furthermore, heat treatment at a temperature in the range of 200°C to 250°C as described above allows the thermal curing of the coating composition to be completed, improving the strength of the release layer.

[0076] <Characteristics evaluation method> (1) Presence or absence of particles The cross section of the laminated film is observed with a scanning electron microscope (SEM), and the image of the foreign matter is processed with an image analyzer. The magnification of the SEM is selected to be 5000 times. 2 The presence or absence of particles was determined by observing 10 randomly selected locations within the range of 0.02 μm or more in equivalent circle diameter. If no particles based on the above definition were observed in this measurement, it was determined that the sample was substantially free of organic and inorganic particles.

[0077] (2) Arithmetic mean surface roughness (SaA, SaB) A 6 cm x 6 cm sample was taken from the biaxially oriented polyester film of the present invention, and for each sample, measurements were performed on the A and B sides of the laminate film of the present invention using a scanning white light interference microscope (device: Hitachi High-Tech Science Corporation's "VertScan" (registered trademark) VS1800) with a 50x objective lens, the measurement mode set to WAVE mode, and a measurement area of ​​113 μm x 113 μm. The sample was set on a stage so that the measurement Y axis was in the longitudinal direction of the sample film (the longitudinal direction is the direction in which the film runs during the film manufacturing process). The sample film to be measured was sandwiched between two metal frames containing rubber packing, so that the film within the frames was taut (removing slack and curl from the sample) and the sample surface was measured.

[0078] The obtained microscopic images were subjected to image processing under the conditions below using the surface analysis software VS-Viewer Version 10.0.3.0 built into the microscope, and then the arithmetic mean surface roughness SaA (nm) and SaB (nm) were determined by selecting the "Height Parameters" along with the analysis conditions below in the "ISO parameter" analysis within the surface analysis software and outputting the obtained group of values ​​into the parameter sheet field. (Image processing conditions) Interpolation: Full interpolation Filtering: Median (3x3 pixels) Surface correction: 4th order (ISO parameter analysis conditions) ISO parameter analysis processing is performed under the following conditions. S-Filter: Automatic Regular probability paper Number of divisions: 300 Calculation range upper limit: 3.000 Lower limit of calculation range: -3.000 Parameters: Select only "Height Parameters" ·Output: Select "Parameter List". (Parameter sheet output) Select "Height Parameters" in the "ISO parameters" window displayed by the ISO parameter analysis above, and then click "Add to parameter sheet." This will use "Sa (nm)" displayed in the "ISO parameters" tab of the "Parameter sheet" window.

[0079] (3) Maximum projection height (SpB) Surface B was measured with a scanning white light interference microscope and image processed in the same manner as in (2) above, and then the maximum protrusion height SpB (nm) was obtained by selecting "Height Parameters" along with the following analysis conditions in the "ISO parameters" analysis within the surface analysis software and outputting the resulting set of values ​​into the parameter sheet field.

[0080] (4) Static friction coefficient (μs) After conditioning the laminated film of the present invention at 23°C and 65% RH, two strips 75 mm wide and 100 mm long were cut out as samples, with the film production line direction as the longitudinal direction. The slip coefficient was measured using a slip coefficient measuring device (Model ST-200, Techno Needs Corporation) in an atmosphere of 23°C and 65% RH. The strip sample was placed and fixed on the measurement sample stage of the device, with the pulling direction of the device in the longitudinal direction of the strip sample and side A facing up. Another strip sample was placed on top of it, with the surface facing up and the pulling direction in the longitudinal direction. Side A was brought into contact with side B, the opposite side, and the end of the sample was fixed to the load detection U-gauge of the device. The film was then left to stand, and a 200g weight was placed on top of it, with a Teflon (registered trademark) sheet with a sample contact surface of 6.5cm x 6.5cm, to bring the samples into close contact with each other, and the static friction coefficient was measured when the upper film was pulled under the following conditions: 10 measurements were made, and the static friction coefficient (μs) was calculated by averaging the six measurements excluding the top two and bottom two points. Measurement distance: 12mm Measurement speed: 210mm / min.

[0081] (5) Tape peeling strength The tape peeling force was measured as follows. First, an acrylic polyester adhesive tape (Nitto Denko Corporation, Nitto 31B tape, 19 mm wide) was laminated onto the release layer of the laminated polyester film of the present invention, and a 2 kgf roller was rolled back and forth once on top of it to create a tape-laminated laminate film. The tape-laminated laminate film was then left to stand for 24 hours in an environment of 25°C and 65% RH, and the peeling force (N / 19 mm) was measured at a peeling angle of 180° and a pulling speed of 300 mm / min using a Shimadzu Corporation universal testing machine "Autograph AG-1S." The average peeling force over a period of 5 to 10 seconds was calculated from the graph of peeling force (N / 19 mm) vs. test time (sec) obtained by the measurement. Similar measurements were performed five times, and the average of the three measurements, excluding the maximum and minimum values, was used as the peeling force (N / 19 mm) of the laminated film.

[0082] (6) Method for analyzing the composition of the release layer The composition of the release layer of the laminated film was analyzed using GCIB-TOF-SIMS (GCIB: gas cluster ion beam, TOF-SIMS: time-of-flight secondary ion mass spectrometry). The measurement conditions were as follows: <Sputtering conditions> Ion source: Argon gas cluster ion beam <Detection conditions> Primary ion: Bi3 ++ (25 keV) Secondary ion polarity: Negative Mass range: m / z 0~1000 Measurement range: 200 x 200 μm 2 The peak intensity of the fragment detected at the maximum intensity in the measurement is K, and the fragment derived from polydimethylsiloxane (SiCH + The peak intensity of the fragment ion (M / Z=43) was defined as P, and the ratio P / K was calculated. When P / K<0.01, it was determined that the release layer did not substantially contain a silicone compound.

[0083] (7) Analysis method for the composition of laminated films In the same manner as in (6) above, the layer having the release layer and the B-side was analyzed using GCIB-TOF-SIMS, and the fragment (CF2 + The peak intensity of the fragment ion (M / Z = 50) was defined as Pf, and the ratio Pf / K was calculated. If Pf / K was less than 0.01, the laminated film was determined to not contain PFAS.

[0084] (8) Intrinsic viscosity A polyester film was dissolved in 100 ml of orthochlorophenol (solution concentration C (measurement sample mass / solution volume) = 1.2 g / 100 ml), and the viscosity of the solution at 25°C was measured using an Ostwald viscometer. The viscosity of the solvent was also measured in the same manner. Using the obtained solution viscosity and solvent viscosity, [η] was calculated according to the following formula (A), and the obtained value was taken as the intrinsic viscosity. Equation (A) ηsp / C=[η]+K[η] 2 C Here, ηsp = (solution viscosity / solvent viscosity)-1, and K is the Huggins constant (assumed to be 0.343). When the solution containing the measurement sample contained insoluble matter such as inorganic particles, the measurement was carried out using the following method. (8-1) Dissolve the measurement sample in 100 mL of orthochlorophenol to prepare a solution with a concentration of 1.2 g / 100 mL or more. The mass of the measurement sample added to the orthochlorophenol is defined as the measurement sample mass. (8-2) Next, the solution containing the insoluble matter is filtered, and the mass of the insoluble matter and the volume of the filtrate after filtration are measured. (8-3) Add orthochlorophenol to the filtrate after filtration to adjust the result to 1.2 g / 100 mL (mass of the measured sample (g) - mass of the insoluble matter (g)) / (volume of the filtered filtrate (mL) + volume of the added orthochlorophenol (mL)). (For example, when a concentrated solution of 2.0 g of measured sample / 100 mL of solution volume is prepared, if the mass of the insoluble matter when the solution is filtered is 0.2 g and the volume of the filtered filtrate is 99 mL, add 51 mL of orthochlorophenol to adjust the result. ((2.0 g - 0.2 g) / (99 mL + 51 mL) = 1.2 g / 100 mL)) (8-4) Using the solution obtained in (8-3), the viscosity at 25°C is measured using an Ostwald viscometer. Using the obtained solution viscosity and solvent viscosity, [η] is calculated according to the above formula (A), and the obtained value is taken as the intrinsic viscosity.

[0085] <Method for evaluating the application characteristics of laminated films> (9) Scratches and defects The continuously produced laminated film was wound into a 4000 m long roll at a transport speed of 100 m / min. At this time, the number of defects resulting from scratches of 100 μm or more that occurred on the roll surface was counted using a defect detector, and the scratches were evaluated as follows. ◯ and △ were considered pass. Good: The number of defects due to scratches in the roll is 4 or less. △: The number of defects due to scratches in the roll is 5 to 10. ×: The number of defects due to scratches in the roll is 11 or more.

[0086] (10) Winding property Ten rolls each having a length of 4000 m were wound at a conveying speed of 100 m / min, and the winding properties of the resulting rolls were evaluated as follows. ◯ and Δ were evaluated as pass. Good: Out of 10 rolls, 2 or less rolls had wrinkles. △: Of 10 rolls, 3 to 6 rolls had wrinkles. ×: Of 10 rolls, 7 or more rolls had wrinkles from winding.

[0087] (11) Winding misalignment Ten rolls each having a length of 4000 m were wound at a conveying speed of 100 m / min, and the resulting rolls were evaluated for winding misalignment as follows: Good and Fair were evaluated as pass. Good: Out of 10 rolls, there were 2 or fewer rolls with misalignment. △: Of 10 rolls, the number of rolls with misalignment was 3 to 6. ×: Out of 10 rolls, 7 or more rolls had misalignment.

[0088] <Method for evaluating the application characteristics of ceramic green sheets> (12) Forming ceramic green sheets (application of ceramic slurry) Glass beads with a number average particle size of 2 mm were added to 100 parts by weight of barium titanate (manufactured by Fuji Titanium Industries Co., Ltd., product name HPBT-1), 10 parts by weight of polyvinyl butyral (manufactured by Sekisui Chemical Co., Ltd., product name BL-1), 5 parts by weight of dibutyl phthalate, and 60 parts by weight of toluene-ethanol (30:30 weight ratio), and the mixture was mixed and dispersed in a jet mill for 20 hours, followed by filtration to prepare a paste-like ceramic slurry. The resulting ceramic slurry was applied to a release film using a die coater to a dry thickness of 1.0 μm, dried, and wound up to obtain a ceramic green sheet.

[0089] (13) Ceramic green sheet peeling The green sheet wound up in (12) above was unwound by hand and visually observed without being peeled off from the release film, and the ceramic green sheet was evaluated for peeling (floating defects) from the release layer as follows. The observed area was 300 mm wide and 500 mm long. ◯ and △ were evaluated as pass. ◯: No peeling of the ceramic green sheet. △: Peeling of the ceramic green sheet was observed in 1 to 3 places. ×: Peeling of the ceramic green sheet was observed in four or more places.

[0090] (14) Surface defects of ceramic green sheets The green sheet wound up in (12) above was unwound by hand and visually inspected without peeling it off from the release film to check for pinholes and the state of coating on the surface and edges of the sheet. The area inspected was 300 mm wide and 500 mm long. The green sheet molded on the release film is illuminated from behind with a 1000 lux backlight unit and observed for pinholes caused by coating voids or dents caused by surface transfer from the back of the release film. ◯ and △ are considered to be pass. ○: No pinholes or dents. △: No pinholes, and 3 or less dents observed. ×: Pinholes are present and 4 or more dents are observed. [Industrial Applicability]

[0091] The laminated film of the present invention has a release layer and a back surface that are highly smooth and have good handleability, and therefore can be suitably used as a processing film for producing electronic parts, such as a ceramic green sheet. [Example]

[0092] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples in any way.

[0093] <Raw materials> (Polyester A) Terephthalic acid and ethylene glycol were polymerized in a conventional manner using antimony trioxide as a catalyst to obtain polyethylene terephthalate pellets (polyester A) which were substantially free of particles and had an intrinsic viscosity of 0.63 dl / g.

[0094] (Polyester B) Polyester B was obtained in the same manner as in the preparation of Polyester A, except that the intrinsic viscosity was set to 0.65 dl / g.

[0095] (Polyester C) An aqueous slurry of divinylbenzene / styrene copolymer crosslinked particles having a volume average particle diameter of 300 nm and a volume shape factor f=0.51, obtained by a monomer adsorption method, was mixed into the above-mentioned homopolyethylene terephthalate pellets containing substantially no particles using a vented twin-screw kneader to obtain polyethylene terephthalate pellets (polyester C) containing 2.0 wt % of divinylbenzene / styrene copolymer crosslinked particles having a volume average particle diameter of 300 nm relative to the polyethylene terephthalate.

[0096] (Polyester D) Polyethylene terephthalate pellets (polyester D) containing 1.0 wt % of divinylbenzene / styrene copolymer crosslinked particles were obtained in the same manner as in the preparation of polyester C, using an aqueous slurry of divinylbenzene / styrene copolymer crosslinked particles with a volume average particle diameter of 450 nm.

[0097] (Polyester E) In producing a polyester in the same manner as in the above polyester A, delta-alumina particles having a volume average particle diameter of 100 nm dispersed in ethylene glycol were added so that the amount added to the polyethylene terephthalate was 1.5 wt %, thereby obtaining delta-alumina-containing polyethylene terephthalate pellets (polyester E).

[0098] <Release agent (A)> (Release agent (A-1): long-chain alkyl group-containing resin) A four-neck flask was charged with 200 parts xylene and 600 parts octadecyl isocyanate and heated with stirring. Once the xylene began to reflux, 100 parts of polyvinyl alcohol with an average degree of polymerization of 500 and a degree of saponification of 88 mol% was added in small increments at 10-minute intervals over approximately 2 hours. After the polyvinyl alcohol addition was completed, the mixture was refluxed for another 2 hours to terminate the reaction. The reaction mixture was cooled to approximately 80°C and then added to methanol. The reaction product precipitated as a white precipitate. This precipitate was then filtered, 140 parts xylene was added, and the mixture was heated to completely dissolve the reaction product. This process was repeated several times, followed by the addition of methanol to precipitate the product. The precipitate was then washed with methanol and dried and pulverized to obtain a long-chain alkyl group-containing resin (A-1: a polymethylene main chain with an alkyl group having 18 carbon atoms in the side chain). This resin was then diluted with water to a concentration of 20% by mass.

[0099] (Release agent (A-2): long-chain alkyl group-containing resin) A 25 mL pressure-resistant glass polymerization ampoule was charged with 2-hydroxyethyl acrylate (HEA) (Kanto Chemical Co., Ltd.), a polymerization initiator α,α'-azobisisobutyronitrile (AIBN) (Kanto Chemical Co., Ltd.), a RAFT agent cumyl dithiobenzoate (CDB), and a solvent toluene in a weight ratio of HEA / CDB / AIBN / toluene = 0.35 / 0.03 / 0.007 / 2.27 (g). Next, the mixed solution in the ampoule was The mixture was degassed twice by freeze-degassing, and the ampoule was sealed and heated in an oil bath at 100°C for 18 hours. After heating for 1 hour, a reaction liquid containing a polymer was obtained.

[0100] The reaction solution in the ampoule contains docosyl acrylate, AIBN as a polymerization initiator, and a solvent. Toluene, the solvent, was added in a weight ratio (g) of docosyl acrylate / AIBN / toluene = 4.65 / 0.003 / 1.3. The mixture was subjected to two cycles of freeze-degassing, after which the ampoule was sealed and heated at 100°C for 48 hours. The polymerized solution was then added dropwise to 20 times the mass of hexane and stirred to precipitate a solid. The resulting solid was filtered and vacuum dried overnight at 40°C to obtain a long-chain alkyl group-containing resin (long-chain alkyl group-containing resin (A-2) which is a block copolymer having an alkyl group with 22 carbon atoms).

[0101] The obtained long-chain alkyl group-containing resin (A-2) was emulsified as follows to obtain an aqueous resin emulsion. A 1-liter homomixer was charged with 375 g of water, and 45 g of polyoxyethylene nonylphenyl ether, 30 g of polyoxyethylene polyoxypropylene glycol, 200 g of long-chain alkyl group-containing resin (A-2), and 150 g of toluene were added in that order, heated to 70°C, and stirred until uniform. This mixture was transferred to a pressure homogenizer and emulsified, after which the pressure was reduced while heating and the toluene was distilled off.

[0102] (Release agent (A-3): silicone-containing resin) Toagosei Co., Ltd.'s "Simac" (registered trademark) US-480 (a silicone graft copolymer with an acrylic backbone, containing hydroxyl and carboxyl groups) was used.

[0103] <Resin or Compound (B)> (Acrylic resin (B-1)) Methyl methacrylate (α), hydroxyethyl methacrylate (β), and a urethane acrylate oligomer (manufactured by Negami Chemical Industrial Co., Ltd., "Art Resin" (registered trademark) UN-3320HA, with 6 acryloyl groups) (γ) were charged into a stainless steel reaction vessel in a mass ratio of (α) / (β) / (γ) = 94 / 1 / 5. Two parts by mass of sodium dodecylbenzenesulfonate as an emulsifier were added per 100 parts by mass of the total of (α) to (γ), and the mixture was stirred to prepare Mixed Solution 1. Next, a reaction apparatus equipped with a stirrer, reflux condenser, thermometer, and dropping funnel was prepared. Sixty parts by weight of Mixed Solution 1, 200 parts by weight of isopropyl alcohol, and 5 parts by weight of potassium persulfate as a polymerization initiator were charged into the reaction apparatus and heated to 60°C to prepare Mixed Solution 2. Mixed Solution 2 was maintained at 60°C for 20 minutes. Next, mixed solution 3 was prepared, consisting of 40 parts by weight of mixed solution 1, 50 parts by weight of isopropyl alcohol, and 5 parts by weight of potassium persulfate. Subsequently, mixed solution 3 was added dropwise to mixed solution 2 over two hours using a dropping funnel to prepare mixed solution 4. Mixed solution 4 was then heated to 60°C and maintained at that temperature for two hours. The resulting mixed solution 4 was cooled to below 50°C and then transferred to a container equipped with a stirrer and pressure-reducing equipment. 60 parts by weight of 25% aqueous ammonia and 900 parts by weight of pure water were added thereto, and the isopropyl alcohol and unreacted monomers were recovered under reduced pressure while heating to 60°C, yielding acrylic resin (B-1) dispersed in pure water.

[0104] (Melamine resin (B-2)) Sanwa Chemical Co., Ltd.'s "Nicalac" (registered trademark) MW-035 (solid content concentration 70 mass %, solvent: water) was used.

[0105] (Polyester resin (B-3)) "Pesresin" (registered trademark) A-640 (solid content concentration 25% by mass, solvent: water) manufactured by Takamatsu Oil & Fats Co., Ltd. was used.

[0106] <Binder resin> (Acrylic resin (C-1)) Under a nitrogen gas atmosphere and reduced pressure, 300 parts of water (solvent) were charged into an emulsion polymerization reactor with 1 part by weight of sodium p-dodecylbenzenesulfonate as an emulsifier, 65 parts by weight of methyl methacrylate (MMA), 30 parts by weight of ethyl acrylate (EMA), 3 parts by weight of N-methylolacrylamide (NMAM), and 2 parts by weight of acrylic acid (AA). 100 parts by weight of sodium persulfate (initiator) was added per 1 million parts by weight of the total monomer components. The reaction was carried out at 30-80°C for 10 hours, and then the pH was adjusted to 7.0-9.0 with aqueous ammonia (alkali). The unreacted monomer was then removed and the mixture was concentrated under reduced pressure at 70°C to obtain an aqueous dispersion of acrylic resin (C-1). The average particle size of the aqueous dispersion of acrylic resin (C-1) was 100 nm, and the Tg was 80°C. <Acrylic resin composition> Methyl methacrylate 65 parts by weight Ethyl acrylate 30 parts by weight N-methylolacrylamide 3 parts by weight · 2 parts by weight of acrylic acid.

[0107] (Polyester resin (C-2)) Under a nitrogen gas atmosphere, 44 moles of 2,6-naphthalenedicarboxylic acid as the dicarboxylic acid component, 3 moles of sodium 5-sulfoisophthalate, and 50 moles of ethylene glycol as the glycol component were charged into an ester exchange reactor, and 100 parts by weight of tetrabutyl titanate (catalyst) was added thereto relative to 1 million parts by weight of the total dicarboxylic acid component. An esterification reaction was carried out at 160 to 240°C for 5 hours, and then the distillate was removed.

[0108] Then, 3 moles of trimellitic acid, a trivalent or higher polycarboxylic acid component, and 100 parts by weight of tetrabutyl titanate per 1 million parts by weight of the total dicarboxylic acids were added, and the distillate was removed at 240°C until the reaction mixture became transparent. Then, a polycondensation reaction was carried out under reduced pressure at 220 to 280°C to obtain polyester resin (C-2). The Tg of the polyester resin was 120°C.

[0109] To 100.0 parts by weight of the polyester resin (C-2), 531.6 parts by weight of water, 2.0 parts by weight of 25% by weight ammonia water, and 33.4 parts by weight of butyl cellosolve were added and dissolved at 40° C. Then, the reaction vessel was sealed, and the internal temperature of the vessel was raised to 120° C. and heated for 2 hours to obtain an aqueous dispersion of polyester resin (C-2). <Composition of Polyester Resin (C-2)> The total of all monomers is 100 parts by mole, and the composition is as follows: (Dicarboxylic acid component and polycarboxylic acid component) 2,6-Naphthalenedicarboxylic acid 44 parts by mole Sodium 5-sulfoisophthalate 3 mole parts 1,3,5-Trimellitic acid 3 mole parts (glycol component) Ethylene glycol 50 mole parts (Polyester resin (C-3)) Under a nitrogen gas atmosphere, 42 molar parts of terephthalic acid as a dicarboxylic acid component and 50 molar parts of ethylene glycol as a glycol component were charged into an ester exchange reactor, and 100 parts by weight of tetrabutyl titanate (catalyst) was added thereto relative to 1 million parts by weight of the total dicarboxylic acid components. An esterification reaction was carried out at 160 to 240°C for 5 hours, and then the distillate was removed.

[0110] Next, 8 moles of trimellitic acid, a trivalent or higher polycarboxylic acid component, and 100 moles of tetrabutyl titanate per 1 million weight parts of total dicarboxylic acids were added to the polyester polyol, and the distillate was removed at 240°C until the reaction mixture became transparent. Then, a polycondensation reaction was carried out under reduced pressure at 220 to 280°C to obtain polyester resin (C-3). The Tg of the polyester resin was 75°C.

[0111] To 100.0 parts by weight of the polyester resin (C-3), 531.6 parts by weight of water, 2.0 parts by weight of 25% by weight ammonia water, and 33.4 parts by weight of butyl cellosolve were added and dissolved at 40° C. Then, the reaction vessel was sealed, and the internal temperature of the vessel was raised to 120° C. and heated for 2 hours to obtain an aqueous dispersion of polyester resin (C-3). <Composition of Polyester Resin (C-3)> The total of all monomers is 100 parts by mole, and the composition is as follows: (Dicarboxylic acid component and polycarboxylic acid component) Terephthalic acid 42 mole parts 1,3,5-Trimellitic acid 8 parts by mole (glycol component) Ethylene glycol 50 mole parts <Particle components> (Silica particles (D-1)) "Spherica" ​​(registered trademark) 140 (silica particles, average particle diameter 140 nm) manufactured by JGC Catalysts and Chemicals Co., Ltd. was used.

[0112] (Silica particles (D-2)) Nippon Shokubai Co., Ltd.'s "Seahoster" (registered trademark) KE-W30 (silica particles, average particle diameter 300 nm) was used.

[0113] Example 1 A mixture of raw materials prepared according to the formulation shown in Table 1 was stirred in a blender and dried under reduced pressure at 120-140°C for at least 1 hour, then fed to an extruder. The mixture was melt-extruded at 275°C, filtered, passed through a slit die maintained at 285°C, and wound around a casting drum maintained at a surface temperature of 25°C, where it was cooled and solidified to obtain an unstretched sheet. The surface temperature of the casting drum was kept at 25°C.

[0114] This unstretched sheet was stretched 3.3 times in the longitudinal direction, and then a release layer and a lubrication layer were applied using an in-line coating method according to the specifications in Table 1. The sheet was then introduced into a tenter and stretched 3.9 times in the width direction, after which it was relaxed by 2.9% in the width direction to obtain a 31 μm thick laminate film intermediate product. This intermediate product was slit using a slitter to obtain a 31 μm thick laminate film. The evaluation results of the obtained film are shown in Table 3.

[0115] Examples 2 to 9 Laminated films having a thickness of 31 μm or 25 μm were obtained in the same manner as in Example 1, except that the configurations of the polyester film, release layer, and lubrication layer were changed as shown in Table 1. The evaluation results of the obtained films are shown in Table 3.

[0116] (Comparative Examples 1 to 9) A roll of a laminated film having a thickness of 31 μm was obtained in the same manner as in Example 1, except that the configurations of the polyester film, release layer, and lubrication layer were changed as shown in Table 2. The evaluation results of the obtained film roll are shown in Table 4.

[0117] [Table 1]

[0118] [Table 2]

[0119] [Table 3]

[0120] Table 4

Claims

1. A laminated film having a release layer on one side of a polyester film and satisfying the following requirements (1) to (3). (1) The polyester film and the release layer are substantially free of particles. (2) When the surface of the release layer is defined as surface A and the arithmetic mean surface roughness of surface A is defined as SaA, SaA is 0.1 nm or more and 6.0 nm or less. (3) When the surface of the laminated film opposite to the surface A is surface B and the arithmetic mean surface roughness of surface B is SaB, SaB is 0.5 nm or more and less than 3.0 nm.

2. 10. The laminate film of claim 1, wherein the laminate film is substantially particle-free.

3. 3. The laminated film according to claim 1, wherein the static friction coefficient μs between the A surface and the B surface is 0.3 or more and 0.8 or less.

4. 3. The laminated film according to claim 1, wherein the tape peel strength of the A-side is 0.1 N / 19 mm or more and 10 N / 19 mm or less.

5. 3. The laminate film according to claim 1, wherein the maximum projection height on the B side is defined as SpB, and SpB is less than 60 nm.

6. 3. The laminate film according to claim 1, wherein, when the surface of the release layer is analyzed by time-of-flight secondary ion mass spectrometry, the ratio (P / K) [-] of the peak intensity (P) of the fragment derived from polydimethylsiloxane to the peak intensity (K) of the fragment detected at the maximum intensity is less than 0.

01.

7. 3. The laminate film according to claim 1, which is free of perfluoroalkyl and polyfluoroalkyl compounds (PFAS).

8. The laminated film according to claim 1 or 2, wherein the layer having the side B is a lubricious layer.

9. 3. The laminated film according to claim 1, which is used as a process film for producing a ceramic green sheet.

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