JP2015059190A - Multilayer polyester film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multilayer polyester film from which an oligomer is hardly eluted even after the multilayer polyester film is exposed to, for example, high temperature and which is suitable: as process paper to be used in a molding simultaneous transfer method or when a flexible printed wiring board or a plastic sheet is produced; as a process film to be used in various processes; and in excellent mold releasability-required applications.SOLUTION: The multilayer polyester film has a coating layer, which is formed from a polyvalent aldehyde compound-containing coating liquid, on one surface thereof and another coating layer, which is formed from a mold releasing agent-containing coating liquid, on the other surface thereof.

Description

  The present invention is used in various processes such as transfer for molding simultaneous transfer, process paper for manufacturing flexible printed wiring boards and plastic sheets, etc., with little oligomer precipitation from the film even after exposure to high temperatures. It is related with the laminated polyester film which can be utilized suitably for the use as which the outstanding mold release property is calculated | required like the film for process.

  Polyester films are excellent in transparency, dimensional stability, mechanical properties, heat resistance, electrical properties, etc., and are used in various fields.

  For example, it is used as a process film used in various processes such as process paper for transfer such as simultaneous molding transfer, process paper for manufacturing a flexible printed wiring board, and plastic sheet. Some process films apply heat or pressure to the film during various processes.

  However, as a problem with polyester films, when exposed to high temperature and long time treatment, oligomers contained in the film (low molecular weight components of polyester, especially ester cyclic trimers) precipitate and crystallize on the film surface. Thus, post-processing defects, in-process and component contamination, and the like occur. Therefore, the characteristics of the process film based on the polyester film cannot be said to be sufficiently satisfactory.

  As a measure for preventing the oligomer precipitation, for example, it is proposed to provide a curable resin layer made of a crosslinked product of a silicone resin and an isocyanate resin on a polyester film (Patent Document 1). However, the curable resin layer is formed by thermosetting, requires high-temperature treatment for dissociation of the blocking agent of the isocyanate resin, and is in a situation where curling and sagging are likely to occur during processing. Care must be taken in handling.

  Therefore, when taking measures to reduce the amount of oligomer precipitation by the coating layer, it is necessary to have higher heat resistance than before and the oligomer sealing performance of the coating layer itself must be good. is there.

  Furthermore, when used as a substrate for a process film, release properties for various resins and adhesives are required. When a polyester film is used as a release film, it has a drawback that it is poor in practicality because of its insufficient release properties.

  In addition, to simplify the process, after transfer processing, inspection may be performed with the process film attached, which is higher in transparency than conventional process films, reduced oligomer precipitation, and excellent. Releasability is being demanded.

JP 2007-320144 A

  The present invention has been made in view of the above circumstances, and its solution is to suppress oligomers precipitated from the film when exposed to high temperatures, for example, during storage of the film, use of the film, processing of the film, etc. It is an object of the present invention to provide a laminated polyester film that does not cause problems associated with the above and has excellent releasability.

  As a result of intensive studies on the above problems, the present inventors have found that the above problems can be solved by providing a specific coating layer, and have completed the present invention.

  That is, the gist of the present invention is to have a coating layer formed from a coating solution containing a polyvalent aldehyde compound on one surface of a polyester film, and a coating layer formed from a coating solution containing a release agent. It exists in the laminated polyester film characterized by having on the other surface.

  According to the laminated polyester film of the present invention, the amount of oligomer precipitation due to high-temperature and long-time treatment is small, and in various processes such as transfer for molding simultaneous transfer, for process paper for manufacturing flexible printed wiring boards and plastic sheets, etc. A substrate film having excellent releasability can be provided as a process film to be used, and its industrial utility value is high.

  The base film of the laminated polyester film of the present invention is made of polyester. Such polyesters include dicarboxylic acids such as terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, adipic acid, sebacic acid, 4,4′-diphenyldicarboxylic acid, 1,4-cyclohexyldicarboxylic acid or esters thereof. It is a polyester produced by melt polycondensation with glycols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol, and 1,4-cyclohexanedimethanol. Polyesters composed of these acid components and glycol components can be produced by arbitrarily using a commonly used method.

  For example, a transesterification reaction between a lower alkyl ester of an aromatic dicarboxylic acid and a glycol, or a direct esterification of an aromatic dicarboxylic acid and a glycol, to form a substantially bisglycol of an aromatic dicarboxylic acid A method is employed in which an ester or a low polymer thereof is formed and then polycondensed by heating under reduced pressure. Depending on the purpose, an aliphatic dicarboxylic acid may be copolymerized.

  Typical examples of the polyester of the present invention include polyethylene terephthalate, polyethylene-2,6-naphthalate, poly-1,4-cyclohexanedimethylene terephthalate, and the like. It may be a polymerized polyester and may contain other components and additives as necessary.

  There is no restriction | limiting in particular as a polymerization catalyst of polyester, A conventionally well-known compound can be used, For example, an antimony compound, a titanium compound, a germanium compound, a manganese compound, an aluminum compound, a magnesium compound, a calcium compound etc. are mentioned. Among these, antimony compounds have the advantage of being inexpensive and having high catalytic activity. Titanium compounds and germanium compounds are preferable because they have high catalytic activity and can be polymerized in a small amount, and since the amount of metal remaining in the film is small, the brightness of the film is increased. Furthermore, since a germanium compound is expensive, it is more preferable to use a titanium compound.

  The polyester film in the present invention may have a single layer structure or a multilayer structure. In the case of a multilayer structure, the surface layer and the inner layer, or both the surface layer and each layer can be made of different polyesters depending on purposes.

  In this invention, in order to suppress the precipitation amount of the ester cyclic trimer after heat processing, manufacturing a film from polyester with little content of ester cyclic trimer is mentioned. Various known methods can be used as a method for producing a polyester having a low ester cyclic trimer content. Examples thereof include a method of solid-phase polymerization after polyester production.

  Precipitation of ester cyclic trimer after heat treatment by designing a layer using a polyester raw material with a low content of ester cyclic trimer in the outermost polyester layer of the polyester film, with a polyester film comprising three or more layers A method of reducing the amount is also possible.

  The content of the ester cyclic trimer contained in the polyester film is about 1% by weight in a general production method, but from the viewpoint of preventing precipitation of the ester cyclic trimer, the content of the ester cyclic trimer Is preferably 0.7% by weight or less, more preferably 0.6% by weight or less. When the polyester cyclic trimer content is 0.7% by weight or less, the effect of preventing the precipitation of the ester cyclic trimer on the film surface is particularly high.

  The polyester used for forming the polyester layer can use a polyester raw material with a low ester cyclic trimer content, and the ester cyclic trimer content is preferably 0.7% by weight or less, More preferably, it is 0.6 weight% or less, Most preferably, it is 0.5 weight% or less. When the content of the ester cyclic trimer in the polyester raw material is 0.7% by weight or less, it becomes possible to more effectively suppress the precipitation amount of the ester cyclic trimer after the heat treatment.

  The polyester layer is preferably composed of 70% by weight or more of polyester having an ester cyclic trimer content of 0.7% by weight or less, more preferably 80% by weight or more. When comprised from 70 weight% or more, it becomes possible to exhibit the ester cyclic trimer precipitation prevention effect to the film surface after heat processing highly.

  When making a polyester film into a multilayer structure, it is preferable from the viewpoint of preventing ester cyclic trimer precipitation that at least one layer of the polyester film has a polyester layer having an ester cyclic trimer content of 0.7% by weight or less.

  Moreover, precipitation of the ester cyclic trimer from the polyester film is effectively suppressed when the polyester layer having a polyester film having an ester cyclic trimer content of 0.7% by weight or less is thicker. The thickness of the polyester layer is preferably 1.5 μm or more, more preferably 2.0 μm or more, and particularly preferably 2.5 μm or more. When the film thickness of the polyester layer is 1.5 μm or more, a long-time heat treatment at 150 ° C., a sputtering process under a high tension condition, a durability test under a high temperature and high humidity atmosphere, etc. Even when used in a processing step under severe conditions, it is possible to further suppress an increase in film haze.

  The polyester film in the present invention can contain particles for the purpose of ensuring the film runnability and preventing scratches. Examples of such particles include inorganic particles such as silica, calcium carbonate, magnesium carbonate, calcium phosphate, kaolin, talc, aluminum oxide, titanium oxide, alumina, barium sulfate, calcium fluoride, lithium fluoride, zeolite, and molybdenum sulfide. Further, organic particles such as crosslinked polymer particles and calcium oxalate, and precipitated particles obtained by precipitating and finely dispersing a part of a metal compound such as a catalyst during the polyester production process can also be used.

  On the other hand, the shape of the particles to be used is not particularly limited, and any of a spherical shape, a block shape, a rod shape, a flat shape, and the like may be used. Moreover, there is no restriction | limiting in particular also about the hardness, specific gravity, a color, etc. These series of particles may be used in combination of two or more as required.

  The particle size and content of the particles to be used are selected according to the use and purpose of the film, but the average particle size (d50) is usually 3 μm or less, preferably 0.02 to 2.8 μm, more preferably 0.8. It is in the range of 03 to 2.5 μm. If the average particle size exceeds 3 μm, the film surface roughness may become too rough, or the particles may easily fall off the film surface.

  About particle | grain content, it is 3 weight% or less normally with respect to the polyester layer containing particle | grains, Preferably it is 0.0003 to 1.0 weight%, More preferably, it is the range of 0.0005 to 0.5 weight%. When there are no or few particles, the transparency of the film becomes high and a good film is obtained, but the slipperiness may be insufficient. In some cases, it is necessary to improve the performance. Further, when the particle content exceeds 3% by weight, the transparency of the film may be insufficient.

  The method for adding particles to the polyester layer is not particularly limited, and a conventionally known method can be adopted. For example, it can be added at any stage for producing the polyester constituting each layer, but it is preferably added after completion of esterification or transesterification.

  In addition to the above-mentioned particles, conventionally known antioxidants, heat stabilizers, lubricants, dyes, pigments, and the like can be added to the polyester film in the present invention as necessary.

  The thickness of the polyester film in the present invention is not particularly limited as long as it can be formed as a film, but is usually 5 to 300 μm, preferably 10 to 280 μm, and more preferably 20 to 250 μm.

  As a film forming method of the film of the present invention, a generally known film forming method can be adopted, and there is no particular limitation. For example, a sheet obtained by melt extrusion is first stretched 2 to 6 times at 70 to 145 ° C. by a roll stretching method to obtain a uniaxially stretched polyester film, and then perpendicular to the previous stretching direction in the tenter. A film is obtained by extending | stretching 2 to 6 times at 80-160 degreeC to the direction, and also heat-processing at 150-250 degreeC for 1 to 600 seconds. Further, at this time, it is preferable to perform relaxation within 20% in the longitudinal direction and / or the transverse direction in the heat treatment zone and / or the cooling zone at the heat treatment outlet.

  The coating layer of the film of the present invention can be provided by any of so-called off-line coating, in which a coating layer is provided later on the formed film, and so-called in-line coating, in which a coating layer is provided during film formation. It is preferably provided by in-line coating, particularly by a coating stretching method in which stretching is performed after coating.

  In-line coating is a method of coating within the process of manufacturing a polyester film, and specifically, a method of coating at any stage from melt extrusion of a polyester to heat setting after stretching and winding up. Usually, it is either a substantially amorphous unstretched sheet obtained by melting and quenching, a stretched uniaxially stretched film, a biaxially stretched film before heat setting, or a film after winding and before winding. Coating. Although not limited to the following, for example, in sequential biaxial stretching, a method of stretching in the transverse direction after coating a uniaxially stretched film stretched in the longitudinal direction (longitudinal direction) is particularly excellent. According to such a method, since film formation and coating layer coating can be performed at the same time, there is a merit in manufacturing cost. Stabilize. Moreover, the polyester film before biaxial stretching is first covered with a resin layer constituting the coating layer, and then the film and the coating layer are stretched at the same time so that the base film and the coating layer are firmly adhered to each other. It will be. In addition, the biaxial stretching of the polyester film is that the film is constrained in the longitudinal / lateral direction by gripping the end of the film with a tenter clip etc. In addition, high temperature can be applied while maintaining flatness. Therefore, since the heat treatment performed after coating can be performed at a high temperature that cannot be achieved by other methods, the film forming property of the coating layer is improved, and the coating layer and the polyester film are firmly adhered. As the polyester film provided with the coating layer, the uniformity of the coating layer, the improvement of the film forming property, and the adhesion between the coating layer and the film often produce preferable characteristics.

  In the case of the coating stretching method, the coating solution to be used is preferably an aqueous solution or an aqueous dispersion for safety reasons in terms of handling, working environment, but water is the main medium and does not exceed the gist of the present invention. If so, an organic solvent may be contained.

  In the present invention, the polyester film has a coating layer (hereinafter sometimes abbreviated as a first coating layer) formed from a coating solution containing a polyvalent aldehyde compound on one surface of the polyester film. It is an essential requirement to have a coating layer (hereinafter sometimes abbreviated as a second coating layer) formed from a coating solution containing a release agent on the surface.

  The first coating layer of the laminated polyester film of the present invention has the purpose of reducing the amount of oligomers precipitated by heating, for example, suppresses the reduction of contamination and whitening of the film in the heating step and each subsequent step, and maintains transparency. It is provided for the purpose. The coating solution may contain other components.

  The polyvalent aldehyde compound in the present invention is a compound having two or more aldehyde groups or a functional group derived from an aldehyde group in one molecule. For example, glyoxal, glutaraldehyde, terephthalaldehyde, cyclohexane Polyaldehyde aldehyde compounds such as dialdehyde, tricyclodecanedialdehyde, norbornane dialdehyde, suberaldehyde, etc., compounds obtained by reaction (protected) of these aldehyde groups to form acetals, thioacetalized compounds, silyl etherification And nitrogenated compounds such as imine, iminium salts and enamines.

  The polyvalent aldehyde compound may be unstable and is preferably used in a form in which an aldehyde group is reacted (protected). In view of stability and reactivity in coating, a form reacted with a hydroxyl group-containing compound, particularly a polyhydric alcohol compound, is preferable, and among them, a type that forms a cyclic structure when reacted with an aldehyde group is more preferable.

  Examples of the polyhydric alcohol compound include polyhydric alcohols such as ethylene glycol, 1,3-propanediol, and glycerin, and saccharides such as glucose and galactose. Among them, saccharides are preferable in consideration of applicability.

  As the polyhydric aldehyde compound, an aliphatic polyhydric aldehyde compound or a derivative thereof is preferable in consideration of the strength of the coating layer and the coating appearance, and among them, glyoxal that increases the amount of aldehyde functional group is more preferable, in particular, the molecular weight. .

  That is, the most preferable form of the polyhydric aldehyde compound in the present invention is a type in which a polyhydric alcohol compound is reacted with glyoxal, and among them, a compound in which a saccharide is reacted with glyoxal.

  For the formation of the first coating layer of the film of the present invention, an ammonium group-containing compound or polyvinyl alcohol is used from the viewpoint of preventing precipitation of the ester cyclic trimer on the film surface by heating, and improving the durability and coating properties of the coating layer. It is preferable to use a crosslinking agent in combination. Among these, from the viewpoint of preventing precipitation of the ester cyclic trimer on the film surface by heating, it is more preferable to use an ammonium group-containing compound or a crosslinking agent, and it is more preferable to use an ammonium group-containing compound in combination.

  That is, a more preferable embodiment of the present invention has a coating layer formed from a coating liquid containing a polyvalent aldehyde compound and at least one compound selected from the group consisting of an ammonium group-containing compound, a crosslinking agent, and polyvinyl alcohol. It is a laminated polyester film.

  The ammonium group-containing compound refers to a polymer compound having an ammonium group in the molecule. For example, a polymer containing a monomer having an ammonium group and an unsaturated double bond as a component can be used.

  Specific examples of such a polymer include a polymer having a constituent represented by the following formula (1) or the following formula (2) as a repeating unit. These homopolymers and copolymers, and other plural components may be copolymerized.

In the above formula (1), R ² is —O— or —NH—, R ³ is an alkylene group, or other structure capable of forming the structure of formula (2), R ¹ , R ⁴ , R ⁵ , R ⁶ Are each a hydrogen atom, an alkyl group, a phenyl group or the like, and these alkyl group and phenyl group may be substituted with the following groups. Substitutable groups include, for example, hydroxy group, amide group, ester group, alkoxy group, phenoxy group, naphthoxy group, thioalkoxy group, thiophenoxy group, cycloalkyl group, trialkylammonium alkyl group, cyano group, halogen, etc. is there.

In said formula (2), R < ¹ >, R < ² > is respectively independently a hydrogen atom, an alkyl group, a phenyl group, etc., These alkyl groups and a phenyl group may be substituted by the group shown below. Substitutable groups include, for example, hydroxyl group, amide group, ester group, alkoxy group, phenoxy group, naphthoxy group, thioalkoxy group, thiophenoxy group, cycloalkyl group, trialkylammonium alkyl group, cyano group, halogen, etc. is there. R ¹ and R ² may be chemically bonded. For example, — (CH ₂ ) _m — (m is an integer of 2 to 5), —CH (CH ₃ ) CH (CH ₃ ) —, -CH = CH-CH = CH - , - CH = CH-CH = N -, - CH = CH-N = C -, - CH 2 OCH 2 -, - (CH 2) 2 O (CH 2) 2 - Etc.

X ⁻ in the above formulas (1) and (2) can be appropriately selected within a range not impairing the gist of the present invention. Examples include halogen ions, sulfonates, phosphates, nitrates, alkyl sulfonates, and carboxylates.

A polymer having a component represented by the above formula (1) is preferable because of excellent transparency of the resulting coating layer. However, in the coating stretching method, heat resistance may be inferior, and when used in the coating stretching method, X ⁻ is preferably not a halogen.

  A compound represented by the above formula (2) or other ammonium base in the polymer skeleton is excellent in heat resistance and is preferable.

  In addition, the polymer in which the component represented by the above formula (1) or (2) and the polyethylene glycol-containing (meth) acrylate are copolymerized has a flexible structure, and is uniform during coating and stretching. An excellent coating layer is obtained and preferable.

  Alternatively, a coating layer having excellent uniformity can also be obtained by coating a polyethylene glycol-containing (meth) acrylate polymer in a coating solution.

  Specific examples of the polyethylene glycol-containing (meth) acrylate include polyethylene glycol monoacrylate, polypropylene glycol monoacrylate, polyethylene glycol diacrylate (the polymerization degree of polyethylene glycol units is preferably in the range of 4 to 14), and polypropylene glycol diacrylate. Acrylate, polytetramethylene glycol diacrylate, poly (ethylene glycol-tetramethylene glycol) diacrylate, poly (propylene glycol-tetramethylene glycol) diacrylate, polyethylene glycol-polypropylene glycol-polyethylene glycol diacrylate, polypropylene glycol-polybutylene glycol Monomethacrylate, methoxypolyethylene glycol Methacrylate, methoxy polyethylene glycol monoacrylate, octoxy polyethylene glycol-polypropylene glycol monomethacrylate, octoxy polyethylene glycol-polypropylene glycol monoacrylate, lauroxy polyethylene glycol monomethacrylate, lauroxy polyethylene glycol monoacrylate, stearoxy polyethylene glycol monomethacrylate, steer Examples include polymers starting from loxypolyethylene glycol monoacrylate, allyloxypolyethylene glycol monomethacrylate, allyloxypolyethylene glycol monoacrylate and the like.

  Moreover, the number average molecular weight of an ammonium group containing compound is 1000-500000 normally, Preferably it is 2000-350,000, More preferably, it is 5000-200000. When the molecular weight is less than 1000, the strength of the coating film may be weak or the heat resistance stability may be poor. On the other hand, when the molecular weight exceeds 500,000, the viscosity of the coating solution increases, and the handleability and applicability may deteriorate.

  Various known crosslinking agents can be used as the crosslinking agent, and examples thereof include melamine compounds, oxazoline compounds, epoxy compounds, isocyanate compounds, carbodiimide compounds, and silane coupling compounds. Moreover, a melamine compound is used suitably from a viewpoint of prevention of precipitation of the ester cyclic trimer on the film surface by heating and improvement of durability and applicability of the coating layer.

  The melamine compound is a compound having a melamine structure in the compound, for example, an alkylolated melamine derivative, a compound partially or completely etherified by reacting an alcohol with an alkylolated melamine derivative, and these Mixtures can be used. As alcohol used for etherification, methyl alcohol, ethyl alcohol, isopropyl alcohol, n-butanol, isobutanol and the like are preferably used. Moreover, as a melamine compound, either a monomer or a multimer more than a dimer may be sufficient, or a mixture thereof may be used. Further, a product obtained by co-condensing urea or the like with a part of melamine can be used, and a catalyst can be used to increase the reactivity of the melamine compound.

  The oxazoline compound is a compound having an oxazoline group in the molecule, and a polymer containing an oxazoline group is particularly preferable, and can be prepared by polymerization of an addition polymerizable oxazoline group-containing monomer alone or with another monomer. Addition polymerizable oxazoline group-containing monomers 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, 2-isopropenyl-5-ethyl-2-oxazoline, and the like can be mentioned, and one or a mixture of two or more thereof can be used. Among these, 2-isopropenyl-2-oxazoline is preferred because it is easily available industrially. The other monomer is not limited as long as it is a monomer copolymerizable with an addition polymerizable oxazoline group-containing monomer. For example, alkyl (meth) acrylate (the alkyl group includes a methyl group, an ethyl group, an n-propyl group, an isopropyl group, (meth) acrylic acid esters such as n-butyl group, isobutyl group, t-butyl group, 2-ethylhexyl group, cyclohexyl group); acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, styrene Unsaturated carboxylic acids such as sulfonic acid and its salts (sodium salt, potassium salt, ammonium salt, tertiary amine salt, etc.); Unsaturated nitriles such as acrylonitrile, methacrylonitrile; (meth) acrylamide, N-alkyl ( (Meth) acrylamide, N, N-dialkyl (meth) acrylamide, As the alkyl group, unsaturated amides such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, t-butyl group, 2-ethylhexyl group and cyclohexyl group); vinyl acetate Vinyl esters such as vinyl propionate; vinyl ethers such as methyl vinyl ether and ethyl vinyl ether; α-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, and one or more of these monomers can be used.

  The amount of the oxazoline group of the oxazoline compound contained in the first coating layer constituting the laminated polyester film in the present invention is usually 0.5 to 10 mmol / g, preferably 3 to 9 mmol / g, more preferably 5 to 8 mmol / g. The range of g. By using it in the above range, the durability of the coating film is improved.

  The epoxy compound is a compound having an epoxy group in the molecule, and examples thereof include condensates of epichlorohydrin with ethylene glycol, polyethylene glycol, glycerin, polyglycerin, bisphenol A and the like hydroxyl groups and amino groups, There are polyepoxy compounds, diepoxy compounds, monoepoxy compounds, glycidylamine compounds, and the like. Examples of the polyepoxy compound include sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether, triglycidyl tris (2-hydroxyethyl) isocyanate, glycerol polyglycidyl ether, trimethylolpropane. Examples of the polyglycidyl ether and diepoxy compound include neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, resorcin diglycidyl ether, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, and propylene glycol diglycidyl ether. , Polypropylene glycol diglycidyl ether, poly Examples of tetramethylene glycol diglycidyl ether and monoepoxy compounds include allyl glycidyl ether, 2-ethylhexyl glycidyl ether, phenyl glycidyl ether, and glycidyl amine compounds such as N, N, N ′, N′-tetraglycidyl-m-xylyl. Examples include range amine and 1,3-bis (N, N-diglycidylamino) cyclohexane.

  The isocyanate compound is a compound having an isocyanate derivative structure typified by isocyanate or blocked isocyanate. Examples of isocyanate include aromatic isocyanates such as tolylene diisocyanate, xylylene diisocyanate, methylene diphenyl diisocyanate, phenylene diisocyanate, and naphthalene diisocyanate, and aromatic rings such as α, α, α ′, α′-tetramethylxylylene diisocyanate. Aliphatic isocyanates such as aliphatic isocyanate, methylene diisocyanate, propylene diisocyanate, lysine diisocyanate, trimethylhexamethylene diisocyanate, hexamethylene diisocyanate, cyclohexane diisocyanate, methylcyclohexane diisocyanate, isophorone diisocyanate, methylene bis (4-cyclohexyl isocyanate), isopropylidene dicyclohexyl diisocyanate Ne Alicyclic isocyanates such as bets are exemplified. Further, polymers and derivatives such as burettes, isocyanurates, uretdiones, and carbodiimide modified products of these isocyanates are also included. These may be used alone or in combination. Among the above isocyanates, aliphatic isocyanates or alicyclic isocyanates are more preferable than aromatic isocyanates in order to avoid yellowing due to ultraviolet rays.

  When used in the state of blocked isocyanate, the blocking agent includes, for example, bisulfites, phenolic compounds such as phenol, cresol, and ethylphenol, and alcohols such as propylene glycol monomethyl ether, ethylene glycol, benzyl alcohol, methanol, and ethanol. Compounds, active methylene compounds such as methyl isobutanoyl acetate, dimethyl malonate, diethyl malonate, methyl acetoacetate, ethyl acetoacetate, acetylacetone, mercaptan compounds such as butyl mercaptan, dodecyl mercaptan, ε-caprolactam, δ-valerolactam, etc. Lactam compounds, amine compounds such as diphenylaniline, aniline, ethyleneimine, acetanilide, acid amide compounds of acetic acid amide, Examples include oxime compounds such as maldehyde, acetoald oxime, acetone oxime, methyl ethyl ketone oxime, and cyclohexanone oxime, and these may be used alone or in combination of two or more.

  In addition, the isocyanate compound in the present invention may be used alone, or may be used as a mixture or bond with various polymers. In the sense of improving the dispersibility and crosslinkability of the isocyanate compound, it is preferable to use a mixture or a bond with a polyester resin or a urethane resin.

  A carbodiimide-based compound is a compound having a carbodiimide structure, and is a compound having one or more carbodiimide structures in the molecule, but for better adhesion, etc., the polycarbodiimide having two or more in the molecule More preferred are system compounds.

  The carbodiimide compound can be synthesized by a conventionally known technique, and generally a condensation reaction of a diisocyanate compound is used. The diisocyanate compound is not particularly limited, and any of aromatic and aliphatic compounds can be used. Specifically, tolylene diisocyanate, xylene diisocyanate, diphenylmethane diisocyanate, phenylene diisocyanate, naphthalene diisocyanate, hexa Examples include methylene diisocyanate, trimethylhexamethylene diisocyanate, cyclohexane diisocyanate, methylcyclohexane diisocyanate, isophorone diisocyanate, dicyclohexyl diisocyanate, and dicyclohexylmethane diisocyanate.

  The content of the carbodiimide group contained in the carbodiimide-based compound is a carbodiimide equivalent (weight of the carbodiimide compound to give 1 mol of carbodiimide group [g]) and is usually 100 to 1000, preferably 250 to 800, more preferably 300. It is in the range of ~ 700. By using it in the above range, the durability of the coating film is improved.

  Furthermore, in order not to lose the effect of the present invention, in order to improve the water solubility and water dispersibility of the polycarbodiimide compound, adding a surfactant, polyalkylene oxide, quaternary ammonium salt of dialkylamino alcohol, You may add and use hydrophilic monomers, such as a hydroxyalkyl sulfonate.

  These cross-linking agents are used in a design that improves the performance of the coating layer by reacting in the drying process or film forming process. It can be inferred that unreacted products of these crosslinking agents, compounds after the reaction, or mixtures thereof exist in the finished coating layer.

  When such a crosslinking component is contained, a component for accelerating crosslinking, for example, a crosslinking catalyst can be used in combination.

  Polyvinyl alcohol is a compound having a polyvinyl alcohol moiety. For example, conventionally known polyvinyl alcohols including modified compounds partially acetalized or butyralized with respect to polyvinyl alcohol can be used. The degree of polymerization of polyvinyl alcohol is not particularly limited, but is usually 100 or more, preferably in the range of 300 to 40,000. When the degree of polymerization is less than 100, the water resistance of the coating layer may decrease. The saponification degree of polyvinyl alcohol is not particularly limited, but is usually 70 mol% or more, preferably in the range of 70 to 99.9 mol%, more preferably 80 to 97 mol%, and particularly preferably 86 to 97 mol%. A saponified polyvinyl acetate of 95 mol% is practically used.

  In addition, particles can be used in combination for the purpose of blocking and improving slipperiness in the formation of the first coating layer. The average particle diameter is preferably 1.0 μm or less, more preferably 0.5 μm or less, and particularly preferably 0.2 μm or less from the viewpoint of transparency of the film. The lower limit is preferably in the range of 0.005 μm or more, more preferably 0.01 μm or more, and particularly preferably larger than the film thickness of the coating layer in order to improve the slipperiness more effectively. Specific examples of the particles include silica, alumina, kaolin, calcium carbonate, and organic particles. Among these, silica is preferable from the viewpoint of transparency.

  In addition, for the formation of the first coating layer of the film of the present invention, it is also possible to use various polymers used for forming the second coating layer described later for improving the coating appearance.

  The release agent used for forming the second coating layer of the film of the present invention is used to improve the release property of the film, and is not particularly limited, and a conventionally known release agent can be used. Examples thereof include long-chain alkyl compounds, waxes, fluorine compounds, and silicone compounds. Among these, long-chain alkyl compounds, waxes, and fluorine compounds are preferable from the viewpoint of low contamination, and long-chain alkyl compounds are more preferable from the viewpoint of excellent releasability. These release agents may be used alone or in combination.

  The long-chain alkyl compound is a compound having a linear or branched alkyl group having 6 or more, preferably 8 or more, and more preferably 12 or more carbon atoms. Examples of the alkyl group include octyl group, decyl group, lauryl group, octadecyl group, and behenyl group. Examples of the compound having an alkyl group include various long-chain alkyl group-containing polymer compounds, long-chain alkyl group-containing amine compounds, long-chain alkyl group-containing ether compounds, and long-chain alkyl group-containing quaternary ammonium salts. . In view of heat resistance and contamination, a polymer compound is preferable. Further, from the viewpoint that an appropriate release property can be obtained effectively with a small content, a polymer compound having a long-chain alkyl group in the side chain is more preferable.

The polymer compound having a long-chain alkyl group in the side chain can be obtained by reacting a polymer having a reactive group with a compound having an alkyl group capable of reacting with the reactive group. Examples of the reactive group include a hydroxyl group, an amino group, a carboxyl group, and an acid anhydride.
Examples of the compound having such a reactive group include polyvinyl alcohol, polyethyleneimine, polyethyleneamine, a reactive group-containing polyester resin, and a reactive group-containing poly (meth) acrylic resin. Among these, polyvinyl alcohol is preferable in view of releasability and ease of handling.

  Examples of the compound having an alkyl group capable of reacting with the reactive group include, for example, long-chain alkyl group-containing isocyanates such as octyl isocyanate, decyl isocyanate, lauryl isocyanate, octadecyl isocyanate, and behenyl isocyanate, octyl chloride, decyl chloride, and lauryl chloride. Long-chain alkyl group-containing acid chlorides such as octadecyl chloride and behenyl chloride, long-chain alkyl group-containing amines, long-chain alkyl group-containing alcohols, and the like. Among these, in view of releasability and ease of handling, it is preferable to use a long-chain alkyl group-containing isocyanate. The carbon number of the long-chain alkyl moiety of the long-chain alkyl group-containing isocyanate is preferably 8 or more, more preferably 12 or more, and still more preferably 18 or more.

  In addition, a polymer compound having a long-chain alkyl group in the side chain can also be obtained by copolymerization of a long-chain alkyl (meth) acrylate polymer or a long-chain alkyl (meth) acrylate and another vinyl group-containing monomer. . Examples of the long-chain alkyl (meth) acrylate include octyl (meth) acrylate, decyl (meth) acrylate, lauryl (meth) acrylate, octadecyl (meth) acrylate, and behenyl (meth) acrylate.

  The fluorine compound is a compound containing a fluorine atom in the compound. Organic fluorine compounds are preferably used in terms of the appearance of coating by in-line coating, and examples thereof include perfluoroalkyl group-containing compounds, polymers of olefin compounds containing fluorine atoms, and aromatic fluorine compounds such as fluorobenzene. . From the viewpoint that moderate water repellency can be obtained with a small content, a compound having a perfluoroalkyl group is preferred. Furthermore, the compound containing a long-chain alkyl compound as described above can also be used as the fluorine compound.

  Examples of the compound having a perfluoroalkyl group include perfluoroalkyl (meth) acrylate, perfluoroalkylmethyl (meth) acrylate, 2-perfluoroalkylethyl (meth) acrylate, and 3-perfluoroalkylpropyl (meth) acrylate. Perfluoroalkyl group-containing (meth) acrylates such as 3-perfluoroalkyl-1-methylpropyl (meth) acrylate and 3-perfluoroalkyl-2-propenyl (meth) acrylate, and polymers thereof, and perfluoroalkylmethyl vinyl ether 2-perfluoroalkyl ethyl vinyl ether, 3-perfluoropropyl vinyl ether, 3-perfluoroalkyl-1-methylpropyl vinyl ether, 3-perfluoroalkyl-2-propenyl vinyl Perfluoroalkyl group-containing vinyl ether and polymers thereof such as ether, and the like. In view of heat resistance and contamination, a polymer is preferable. The polymer may be a single compound or a polymer of multiple compounds. Moreover, it is preferable that a perfluoroalkyl group has 3-18 carbon atoms from a viewpoint that the residual water on a film can be suppressed with little content. Further, it may be a polymer with a compound containing a long-chain alkyl compound as described above.

  The wax is a wax selected from natural waxes, synthetic waxes, and blended waxes thereof. Natural waxes are plant waxes, animal waxes, mineral waxes, and petroleum waxes. Examples of plant waxes include candelilla wax, carnauba wax, rice wax, wood wax, and jojoba oil. Animal waxes include beeswax, lanolin, and whale wax. Examples of the mineral wax include montan wax, ozokerite, and ceresin. Examples of petroleum wax include paraffin wax, microcrystalline wax, and petrolatum. Synthetic waxes include synthetic hydrocarbons, modified waxes, hydrogenated waxes, fatty acids, acid amides, amines, imides, esters, and ketones. As synthetic hydrocarbons, Fischer-Tropsch wax (also known as Sazoir wax) and polyethylene wax are famous, but in addition to this, low molecular weight polymers (specifically, polymers having a viscosity number average molecular weight of 500 to 20000) Some of the following polymers are also included. That is, there are polypropylene, ethylene / acrylic acid copolymer, polyethylene glycol, polypropylene glycol, polyethylene glycol and polypropylene glycol block or graft conjugate. Examples of the modified wax include montan wax derivatives, paraffin wax derivatives, and microcrystalline wax derivatives. The derivative herein is a compound obtained by any of purification, oxidation, esterification, saponification treatment, or a combination thereof. Hydrogenated waxes include hardened castor oil and hardened castor oil derivatives. Among these waxes, synthetic hydrocarbons are preferable from the viewpoint of stable performance and easy availability, and oxidized polyethylene wax and oxidized polypropylene wax are more preferable.

The silicone compound is a compound having a silicone structure in the molecule, and examples thereof include silicone emulsion, acrylic graft silicone, silicone graft acrylic, amino-modified silicone, perfluoroalkyl-modified silicone, and alkyl-modified silicone. In view of heat resistance and contamination, it is preferable to contain a curable silicone resin.
As the type of the curable silicone resin, any of the curing reaction types such as an addition type, a condensation type, an ultraviolet curable type, and an electron beam curable type can be used.

  In the formation of the second coating layer of the film of the present invention, it is possible to use a crosslinking agent and various polymers in combination for improving coating film strength, coating coating appearance and transparency, and controlling releasability. It is.

  As the crosslinking agent used for forming the second coating layer of the film of the present invention, various crosslinking agents described in the first coating layer can be used. Among the crosslinking agents, a melamine compound is particularly preferable from the viewpoint of easy release control. In addition, an isocyanate compound is preferably used from the viewpoint that there is little deterioration in releasability due to heat during processing.

  Specific examples of the polymer include polyester resin, acrylic resin, urethane resin, polyvinyl (polyvinyl alcohol, vinyl chloride vinyl acetate copolymer), polyalkylene glycol, polyalkyleneimine, methylcellulose, hydroxycellulose, starches and the like. Among these, polyester resin, acrylic resin, and urethane resin are preferable, and polyester resin is more preferable in terms of easy release control.

  The polyester resin includes, for example, those composed of the following polyvalent carboxylic acid and polyvalent hydroxy compound as main constituent components. That is, as the polyvalent carboxylic acid, terephthalic acid, isophthalic acid, orthophthalic acid, phthalic acid, 4,4′-diphenyldicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, and 2,6 -Naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 2-potassium sulfoterephthalic acid, 5-sodium sulfoisophthalic acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, glutar Acid, succinic acid, trimellitic acid, trimesic acid, pyromellitic acid, trimellitic anhydride, phthalic anhydride, p-hydroxybenzoic acid, trimellitic acid monopotassium salt and ester-forming derivatives thereof can be used. As the polyvalent hydroxy compound, ethylene Recall, 1,2-propylene glycol, 1,3-propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, 2-methyl-1,5-pentanediol , Neopentyl glycol, 1,4-cyclohexanedimethanol, p-xylylene glycol, bisphenol A-ethylene glycol adduct, diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol Polytetramethylene glycol, polytetramethylene oxide glycol, dimethylolpropionic acid, glycerin, trimethylolpropane, sodium dimethylolethylsulfonate, potassium dimethylolpropionate, and the like can be used. One or more compounds may be appropriately selected from these compounds, and a polyester resin may be synthesized by a conventional polycondensation reaction.

  The acrylic resin is a polymer composed of a polymerizable monomer having a carbon-carbon double bond, as typified by acrylic and methacrylic monomers. These may be either a homopolymer or a copolymer. Moreover, the copolymer of these polymers and other polymers (for example, polyester, polyurethane, etc.) is also included. For example, a block copolymer or a graft copolymer. Alternatively, a polymer (possibly a mixture of polymers) obtained by polymerizing a polymerizable monomer having a carbon-carbon double bond in a polyester solution or a polyester dispersion is also included. Similarly, a polymer (in some cases, a mixture of polymers) obtained by polymerizing a polymerizable monomer having a carbon-carbon double bond in a polyurethane solution or polyurethane dispersion is also included. Similarly, a polymer obtained by polymerizing a polymerizable monomer having a carbon-carbon double bond in another polymer solution or dispersion (in some cases, a polymer mixture) is also included. Moreover, it is also possible to contain a hydroxyl group and an amino group.

  The polymerizable monomer having a carbon-carbon double bond is not particularly limited, but particularly representative compounds include, for example, acrylic acid, methacrylic acid, crotonic acid, itaconic acid, fumaric acid, maleic acid, citracone. Various carboxyl group-containing monomers such as acids, and salts thereof; 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, monobutyl hydroxyl fumarate, Various hydroxyl group-containing monomers such as monobutylhydroxy itaconate; various monomers such as methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, lauryl (meth) acrylate ( (Meth) acrylic acid esters; Various nitrogen-containing compounds such as meth) acrylamide, diacetone acrylamide, N-methylolacrylamide or (meth) acrylonitrile; various styrene derivatives such as styrene, α-methylstyrene, divinylbenzene, vinyltoluene, vinyl propionate Various vinyl esters such as: Various silicon-containing polymerizable monomers such as γ-methacryloxypropyltrimethoxysilane, vinyltrimethoxysilane, etc .; Phosphorus-containing vinyl monomers; Various such as vinyl chloride and biridene chloride And various conjugated dienes such as butadiene.

  The urethane resin is a polymer compound having a urethane bond in the molecule. Usually, urethane resin is prepared by reaction of polyol and isocyanate. Examples of the polyol include polycarbonate polyols, polyester polyols, polyether polyols, polyolefin polyols, and acrylic polyols. These compounds may be used alone or in combination.

  Polycarbonate polyols are obtained from a polyhydric alcohol and a carbonate compound by a dealcoholization reaction. Examples of the polyhydric alcohols include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentane. Diol, 1,6-hexanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decane Diol, neopentyl glycol, 3-methyl-1,5-pentanediol, 3,3-dimethylol heptane and the like can be mentioned. Examples of the carbonate compound include dimethyl carbonate, diethyl carbonate, diphenyl carbonate, and ethylene carbonate. Examples of polycarbonate polyols obtained from these reactions include poly (1,6-hexylene) carbonate, poly (3- And methyl-1,5-pentylene) carbonate.

  Polyester polyols include polycarboxylic acids (malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, sebacic acid, fumaric acid, maleic acid, terephthalic acid, isophthalic acid, etc.) or their acid anhydrides. Product and polyhydric alcohol (ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 2-methyl-1,3-propanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 2-methyl-2,4-pentanediol 2-methyl-2-propyl-1 3-propanediol, 1,8-octanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl-1,3-hexanediol, 2,5-dimethyl-2,5-hexanediol 1,9-nonanediol, 2-methyl-1,8-octanediol, 2-butyl-2-ethyl-1,3-propanediol, 2-butyl-2-hexyl-1,3-propanediol, cyclohexane Diol, bishydroxymethylcyclohexane, dimethanolbenzene, bishydroxyethoxybenzene, alkyl dialkanolamine, lactone diol, etc.).

  Examples of polyether polyols include polyethylene glycol, polypropylene glycol, polyethylene propylene glycol, polytetramethylene ether glycol, polyhexamethylene ether glycol, and the like.

  Examples of the polyisocyanate compound used for obtaining the urethane resin include aromatic diisocyanates such as tolylene diisocyanate, xylylene diisocyanate, methylene diphenyl diisocyanate, phenylene diisocyanate, naphthalene diisocyanate, and tolidine diisocyanate, α, α, α ′, α ′. -Aliphatic diisocyanates having aromatic rings such as tetramethylxylylene diisocyanate, aliphatic diisocyanates such as methylene diisocyanate, propylene diisocyanate, trimethylhexamethylene diisocyanate, hexamethylene diisocyanate, cyclohexane diisocyanate, methylcyclohexane diisocyanate, isophorone diisocyanate, dicyclohexyl Methanzi Cyanate, alicyclic diisocyanates such as isopropylidene dicyclohexyl diisocyanates. These may be used alone or in combination.

  A chain extender may be used when synthesizing the urethane resin, and the chain extender is not particularly limited as long as it has two or more active groups that react with an isocyanate group. Alternatively, a chain extender having two amino groups can be mainly used.

  Examples of the chain extender having two hydroxyl groups include aliphatic glycols such as ethylene glycol, propylene glycol and butanediol, aromatic glycols such as xylylene glycol and bishydroxyethoxybenzene, and esters such as neopentyl glycol hydroxypivalate. And glycols such as glycols. Examples of the chain extender having two amino groups include aromatic diamines such as tolylenediamine, xylylenediamine, and diphenylmethanediamine, ethylenediamine, propylenediamine, hexanediamine, 2,2-dimethyl-1,3- Propanediamine, 2-methyl-1,5-pentanediamine, trimethylhexanediamine, 2-butyl-2-ethyl-1,5-pentanediamine, 1,8-octanediamine, 1,9-nonanediamine, 1,10- Aliphatic diamines such as decane diamine, 1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane, dicyclohexylmethanediamine, isopropylidenecyclohexyl-4,4′-diamine, 1,4-diaminocyclohexane, 1, 3-Bisaminomethylcyclohexa And alicyclic diamines such as

  The urethane resin in the present invention may use a solvent as a medium, but preferably uses water as a medium. In order to disperse or dissolve the urethane resin in water, there are a forced emulsification type using an emulsifier, a self-emulsification type in which a hydrophilic group is introduced into the urethane resin, and a water-soluble type. In particular, the self-emulsification type in which an ionic group is introduced into the structure of the urethane resin to form an ionomer is preferable because of excellent storage stability of the liquid and water resistance and transparency of the resulting coating layer. Examples of the ionic group to be introduced include various groups such as a carboxyl group, sulfonic acid, phosphoric acid, phosphonic acid, quaternary ammonium salt, and the like, and a carboxyl group is preferable. As a method for introducing a carboxyl group into a urethane resin, various methods can be taken in each stage of the polymerization reaction. For example, there are a method of using a carboxyl group-containing resin as a copolymer component during prepolymer synthesis, and a method of using a component having a carboxyl group as one component such as polyol, polyisocyanate, and chain extender. In particular, a method in which a desired amount of carboxyl groups is introduced using a carboxyl group-containing diol depending on the amount of this component charged is preferred. For example, dimethylolpropionic acid, dimethylolbutanoic acid, bis- (2-hydroxyethyl) propionic acid, bis- (2-hydroxyethyl) butanoic acid and the like are copolymerized with a diol used for polymerization of a urethane resin. Can do. The carboxyl group is preferably in the form of a salt neutralized with ammonia, amine, alkali metal, inorganic alkali or the like. Particularly preferred are ammonia, trimethylamine and triethylamine. In such a polyurethane resin, a carboxyl group from which a neutralizing agent is removed in a drying step after coating can be used as a crosslinking reaction point by another crosslinking agent. Thereby, it is possible to further improve the durability, solvent resistance, water resistance, blocking resistance, and the like of the obtained coating layer, as well as excellent stability in a liquid state before coating.

  Moreover, in the range which does not impair the main point of this invention, it is also possible to use particle | grains together for the purpose of the formation of the coating layer of the film of this invention for the purpose of the blocking property of a coating layer, slipperiness improvement, etc.

  Further, in the range not impairing the gist of the present invention, an antifoaming agent, a coating property improver, a thickener, an organic lubricant, an antistatic agent, an ultraviolet absorber, and an antioxidant are formed as necessary for forming the coating layer. It is also possible to use a foaming agent, a dye, a pigment and the like in combination.

  As a ratio with respect to all the non-volatile components in the coating liquid which forms the 1st coating layer which comprises the laminated polyester film in this invention, the ratio of a polyvalent aldehyde type compound is the range of 0.01 to 99 weight% normally, Preferably it is 1. It is in the range of ˜50% by weight, more preferably in the range of 3 to 30%. When the ratio is out of the above range, precipitation of the ester cyclic trimer after heating cannot be effectively suppressed or the appearance of coating may be deteriorated.

  From the viewpoint of preventing precipitation of the ester cyclic trimer after heating, when using an ammonium group-containing compound for the formation of the first coating layer, the ratio of the ammonium group-containing compound as a ratio to the total nonvolatile components in the coating solution is: Usually, it is 1 to 99% by weight, preferably 10 to 80% by weight, more preferably 20 to 70% by weight or more. When the ratio is within the above range, precipitation of the ester cyclic trimer after heating can be effectively suppressed.

  From the viewpoint of durability of the coating film and prevention of precipitation of the ester cyclic trimer after heating, when a cross-linking agent is used to form the first coating layer, the ratio of the cross-linking agent as a ratio to the total nonvolatile components in the coating liquid Is usually in the range of 1 to 99% by weight, preferably in the range of 2 to 95% by weight, more preferably in the range of 5 to 90% by weight. When the ratio is within the above range, the durability of the coating film is improved, and the prevention of precipitation of the ester cyclic trimer after heating is also effectively exhibited.

  From the viewpoint of coating appearance and prevention of precipitation of the ester cyclic trimer after heating, when polyvinyl alcohol is used for forming the first coating layer, the proportion of polyvinyl alcohol is usually as a proportion of all nonvolatile components in the coating solution. The range is 1 to 99% by weight, preferably 5 to 90% by weight, and more preferably 10 to 85% by weight. When the ratio is within the above range, a good coating appearance can be obtained, and precipitation of the ester cyclic trimer after heating can be effectively suppressed.

  As a ratio with respect to all the non-volatile components in the coating liquid forming the second coating layer constituting the laminated polyester film in the present invention, the ratio of the release agent is usually 1% by weight or more, preferably in the range of 5 to 95% by weight, More preferably, it is the range of the range of 20 to 90 weight%. When the ratio is out of the above range, sufficient releasability may not be obtained or the coating appearance may be deteriorated.

  From the viewpoint of improving coating film strength, coating appearance and transparency, when a crosslinking agent is used for forming the second coating layer, the crosslinking agent is usually 99% by weight or less, as a proportion of all nonvolatile components in the coating solution, More preferably, it is the range of 5-95 weight%, More preferably, it is the range of 10-80 weight%. Within these ranges, good coating appearance and transparency are easily obtained, and the coating film strength is improved.

  Analysis of various components in the coating layer can be performed by analysis of TOF-SIMS, ESCA, fluorescent X-rays, and the like.

  The film thickness of the coating layer provided on the laminated polyester film in the present invention is usually in the range of 0.001 μm to 1 μm, preferably 0.01 μm to 0, as the thickness of the coating layer on the finally obtained film. 0.5 μm, more preferably in the range of 0.02 to 0.2 μm. When the thickness is thinner than this, the performance may not be sufficiently exhibited. On the other hand, if it is thicker than this, problems such as deterioration of the appearance of the coating layer and easy blocking may occur.

  Examples of methods for applying a coating solution to a polyester film include air doctor coating, blade coating, rod coating, bar coating, knife coating, squeeze coating, impregnation coating, reverse roll coating, transfer roll coating, gravure coating, and kiss roll coating. Conventional coating methods such as cast coating, spray coating, curtain coating, calendar coating, and extrusion coating can be used.

  In order to improve the applicability and adhesion of the coating agent to the film, the film may be subjected to chemical treatment, corona discharge treatment, plasma treatment or the like before coating.

  Regarding the laminated polyester film in the present invention, for example, even after being exposed to a high-temperature atmosphere for a long time, such as a process film, inspection may be performed with the process film attached, and high transparency is required. May be. From this viewpoint, in order to cope with a high degree of transparency, the film haze change amount (ΔH) in heat treatment (150 ° C., 90 minutes) is preferably 1.0% or less, more preferably 0.7% or less. More preferably, it is 0.5% or less. When ΔH exceeds 1.0%, the transparency decreases due to the increase in film haze due to precipitation of ester cyclic trimer, and it is inappropriate when inspection is performed with the process film attached. There is.

Further, from the viewpoint of the precipitation amount of the ester cyclic trimer, the amount of the ester cyclic trimer extracted from the film surface by dimethylformamide by heat treatment (150 ° C., 90 minutes) of the laminated polyester film in the present invention is preferably 1.0 mg / m ² or less, more preferably 0.7 mg / m ² or less, and still more preferably 0.4 mg / m ² or less. In the case where it exceeds 1.0 mg / m ² , in the subsequent step, for example, the precipitation amount of the ester cyclic trimer increases with heat treatment in a high temperature atmosphere such as 150 ° C. for 90 minutes, and the transparency of the film There is a concern that the performance may deteriorate or contamination of the process.

  In the viewpoint of the peeling force of the second coating layer in the present invention, in the evaluation of the peeling force of the second coating layer described later, it is preferably 2200 mN / cm or less, more preferably 1500 mN / cm or less, further preferably 900 mN / cm or less, Particularly preferably, it is 400 mN / cm or less. If it exceeds 2200 mN / cm, the material formed on the second coating layer may not be peeled off successfully.

  The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to the following examples unless it exceeds the gist. In addition, the evaluation method in an Example and a comparative example is as follows.

(1) Measuring method of intrinsic viscosity of polyester 1 g of polyester was precisely weighed, 100 ml of a mixed solvent of phenol / tetrachloroethane = 50/50 (weight ratio) was added and dissolved, and the measurement was performed at 30 ° C.

(2) Measuring method of average particle size (d50: μm) Integration (weight basis) 50% in equivalent spherical distribution measured using centrifugal sedimentation type particle size distribution measuring device (SA-CP3 type manufactured by Shimadzu Corporation) Was the average particle size.

(3) Coating layer thickness A film was fixed with an embedding resin, a cross section was cut with a microtome, and a sample was prepared by staining with 2% osmic acid at 60 ° C. for 2 hours. The obtained sample was observed with a transmission electron microscope (JEM2010 manufactured by JEOL Ltd.), and the thickness of the coating layer was measured. A total of 15 points on the film are measured, and an average of 9 points excluding 3 points from the larger value and 3 points from the smaller value is defined as the coating layer thickness.

(4) Heat treatment method of the film The sample is measured with the measurement surface exposed, and is overlapped with the Kent paper and fixed, and left in a nitrogen atmosphere at 150 ° C. for 90 minutes for heat treatment.

(5) Measurement of film haze Film haze was measured for the sample film according to JIS-K-7136 with a haze meter “HM-150” manufactured by Murakami Color Research Laboratory.

(6) Measurement of film haze increase (ΔH) by heat treatment First, after drying the pressure-sensitive adhesive prepared as described below on the surface of the sample film opposite to the surface provided with the coating layer of the present invention. The film was applied to a thickness of 25 μm and dried to obtain a laminated film provided with a pressure-sensitive adhesive layer on the film.
《Adhesive preparation method》
Japan is an isocyanate crosslinking agent for a solution of acrylic polymer having a weight average molecular weight of 2 million consisting of a copolymer of butyl acrylate / acrylic acid / 2-hydroxyethyl acrylate in a weight ratio of 100/6 / 0.1. Coronate L manufactured by Polyurethane Industry Co., Ltd., silane coupling agent KBM403 manufactured by Shin-Etsu Chemical Co., Ltd., and ethyl acetate were added to prepare a pressure-sensitive adhesive solution having a solid content concentration of 10%. In terms of solid content in the solution, acrylic copolymer / coronate L / KBM403 = 100/3 / 0.6.
The haze of the obtained sample was measured by the method of item (5) (haze 1).
Next, using the surface opposite to the active energy ray-curable resin layer of the sample as the measurement surface, the sample was heated by the method of (4), and then the haze was measured by the method of (5) (haze 2).
ΔH = (haze 2) − (haze 1)
The lower ΔH, the lower the amount of oligomer precipitation due to the high temperature treatment, and the better.

(7) Measurement of amount of ester cyclic trimer deposited on the surface of the laminated polyester film The polyester film is heated in air at 150 ° C. for 90 minutes. Thereafter, the heat-treated film is formed into a box shape with the measurement surface (coating layer) as the inner surface so that the upper part is 10 cm in length and width and the height is 3 cm. Next, 4 ml of DMF (dimethylsulfoamide) was placed in the box prepared by the above method and allowed to stand for 3 minutes, and then DMF was recovered and subjected to liquid chromatography (manufactured by Shimadzu Corporation: LC-7A, mobile phase A: Acetonitrile, mobile phase B: 2% aqueous acetic acid, column: “MCI GEL ODS 1HU” manufactured by Mitsubishi Chemical Corporation, column temperature: 40 ° C., flow rate: 1 ml / min, detection wavelength: 254 nm) The amount of oligomer was determined, and this value was divided by the film area with which DMF was contacted to obtain the amount of oligomer on the film surface (mg / m ² ). The ester cyclic trimer in DMF was determined from the peak area ratio between the standard sample peak area and the measured sample peak area (absolute calibration curve method). The standard sample was prepared by accurately weighing the pre-sorted ester cyclic trimer and dissolving it in accurately measured DMF.

(8) Evaluation of peel strength of second coating layer Adhesive tape (“No. 31B” manufactured by Nitto Denko Corporation) was reciprocally pressed with a 2 kg rubber roller on the surface of the release layer of the sample film, and at room temperature for 1 hour. The peel force after standing was measured. For the peeling force, “Ezgraph” manufactured by Shimadzu Corporation was used, and 180 ° peeling was performed under the condition of a tensile speed of 300 mm / min.

The polyester used in the examples and comparative examples was prepared as follows.
<Method for producing polyester (A)>
Using 100 parts by weight of dimethyl terephthalate and 60 parts by weight of ethylene glycol as starting materials, 0.09 parts by weight of magnesium acetate tetrahydrate as a catalyst is placed in the reactor, the reaction start temperature is set to 150 ° C., and the methanol is distilled off gradually. The reaction temperature was raised to 230 ° C. after 3 hours. After 4 hours, the transesterification reaction was substantially terminated. After adding 0.04 part of ethyl acid phosphate to this reaction mixture, 0.04 part of antimony trioxide was added, and a polycondensation reaction was carried out for 4 hours. That is, the temperature was gradually raised from 230 ° C. to 280 ° C. On the other hand, the pressure was gradually reduced from normal pressure, and finally 0.3 mmHg. After the start of the reaction, the reaction was stopped at a time corresponding to an intrinsic viscosity of 0.63 due to a change in stirring power of the reaction tank, and the polymer was discharged under nitrogen pressure. The obtained polyester (A) had an intrinsic viscosity of 0.63 and an ester cyclic trimer content of 0.97% by weight.

<Method for producing polyester (B)>
The polyester (A) is pre-crystallized at 160 ° C. in advance, and then solid-phase polymerized in a nitrogen atmosphere at a temperature of 220 ° C., and has an intrinsic viscosity of 0.75 and an ester cyclic trimer content of 0.46% by weight. Polyester (B) was obtained.

<Method for producing polyester (C)>
100 parts by weight of dimethyl terephthalate, 60 parts by weight of ethylene glycol, 30 ppm of ethyl acid phosphate with respect to the resulting polyester, and 100 ppm of magnesium acetate tetrahydrate with respect to the resulting polyester as the catalyst at 260 ° C. in a nitrogen atmosphere at 260 ° C. The reaction was allowed to proceed. Subsequently, 50 ppm of tetrabutyl titanate was added to the resulting polyester, the temperature was raised to 280 ° C. over 2 hours and 30 minutes, the pressure was reduced to 0.3 kPa in absolute pressure, and melt polycondensation was further carried out for 80 minutes. A polyester (C) having 0.61 and an ester cyclic trimer content of 1.02% by weight was obtained.

<Method for producing polyester (D)>
Polyester (C) was pre-crystallized at 160 ° C. in advance, and then solid-phase polymerized in a nitrogen atmosphere at a temperature of 210 ° C., with an intrinsic viscosity of 0.72 and an ester cyclic trimer content of 0.50% by weight. Polyester (D) was obtained.

<Method for producing polyester (E)>
In the method for producing polyester (A), after adding 0.04 part of ethyl acid phosphate, 0.5 part of silica particles having an average particle diameter (d50) of 1.6 μm dispersed in ethylene glycol were added. Polyester (E) was obtained using the same method as the production method of polyester (A) except that .04 parts was added and the polycondensation reaction was stopped at the time corresponding to the intrinsic viscosity of 0.65. The obtained polyester (E) had an intrinsic viscosity of 0.65 and an ester cyclic trimer content of 0.82% by weight.

Moreover, the following was used as a composition contained in a coating liquid.
(A1): Polyhydric aldehyde compound obtained by reacting glyoxal with anhydrous glucose (B1): Polyvinyl alcohol (B2) having a saponification degree = 88 mol% and a polymerization degree of 500: Water dispersion of a polyester resin copolymerized with the following composition Monomer composition: (acid component) terephthalic acid / isophthalic acid / 5-sodium sulfoisophthalic acid // (diol component) ethylene glycol / 1,4-butanediol / diethylene glycol = 56/40/4 // 70/20 / 10 (mol%)
(E1): Copolymer having a weight ratio of 75/12/15/30 of 2- (trimethylamino) ethyl methacrylate / ethyl methacrylate / butyl methacrylate / polyethylene glycol-containing monoacrylate whose counter ion is methyl sulfonate.

(C1): Hexamethoxymethylolmelamine (C2): Epocros (made by Nippon Shokubai Co., Ltd.) which is an oxazoline compound. Oxazoline group amount 7.7 mmol / g
(C3): Polyglycerol polyglycidyl ether (C4): Block polyisocyanate synthesized by the following method 1000 parts of hexamethylene diisocyanate was stirred at 60 ° C., and 0.1 part of tetramethylammonium capryate was added as a catalyst. After 4 hours, 0.2 part of phosphoric acid was added to stop the reaction, and an isocyanurate type polyisocyanate composition was obtained. 100 parts of the obtained isocyanurate type polyisocyanate composition, 42.3 parts of methoxypolyethylene glycol having a number average molecular weight of 400, and 29.5 parts of propylene glycol monomethyl ether acetate were charged and maintained at 80 ° C. for 7 hours. Thereafter, the reaction solution temperature was kept at 60 ° C., 35.8 parts of methyl isobutanoyl acetate, 32.2 parts of diethyl malonate, and 0.88 part of 28% methanol solution of sodium methoxide were added and kept for 4 hours. Block polyisocyanate obtained by adding 58.9 parts of n-butanol and maintaining the reaction solution temperature at 80 ° C. for 2 hours, and then adding 0.86 part of 2-ethylhexyl acid phosphate.

(C5): Carbodilite which is a polycarbodiimide compound (Nisshinbo Chemical Co., Ltd.): Carbodiimide equivalent 340
(D1): 200 parts of xylene and 600 parts of octadecyl isocyanate were added to a four-necked flask and heated with stirring. From the time when xylene began to reflux, 100 parts of polyvinyl alcohol having an average degree of polymerization of 500 and a degree of saponification of 88 mol% was added in small portions over a period of about 2 hours. After the addition of polyvinyl alcohol, the reaction was completed by further refluxing for 2 hours. When the reaction mixture was cooled to about 80 ° C. and added to methanol, the reaction product was precipitated as a white precipitate. This precipitate was filtered off, added with 140 parts of xylene, and heated to dissolve completely. After repeating the operation of adding methanol again to precipitate several times, the precipitate was washed with methanol, dried and pulverized to obtain a long-chain alkylated rod (D2): a fluorine compound polymerized with the following composition Water dispersion Octadecyl acrylate / perfluorohexyl ethyl methacrylate / vinyl chloride = 66/17/17 (% by weight)

(D3): An emulsification facility having an internal volume of 1.5 L equipped with a stirrer, a thermometer and a temperature controller, melting point 105 ° C., oxidation 16 mg KOH / g, density 0.93 g / mL, average molecular weight 5000 oxidized polyethylene wax 300 g, ion exchange 650 g of water and 50 g of decaglycerin monooleate surfactant and 10 g of 48% aqueous potassium hydroxide solution were added. After replacing with nitrogen, sealed, stirred at 150 ° C. for 1 hour at high speed, cooled to 130 ° C., and then a high-pressure homogenizer Emulsion (F1): silica particles (F2) having an average particle size of 0.07 μm: alumina-modified silica particles having an average particle size of 0.02 μm

Example 1:
Polyesters (B) and (E) blended at a weight ratio of 80/20 as the surface layer and polyester (A) alone as the raw material for the intermediate layer were each fed to two extruders and heated to 285 ° C. After heating and melting, the layer A is the outermost layer (surface layer), the layer B is the intermediate layer, and the thickness composition ratio is A / B / A = 2.5 / 45/2 with two types and three layers (A / B / A). The film was coextruded so as to be .5 and cooled and solidified while being closely adhered to a mirror surface cooling drum having a surface temperature of 40 to 50 ° C. by using an electrostatic adhesion method, thereby preparing an unstretched polyethylene terephthalate film. The film was stretched 3.4 times in the longitudinal direction using the difference in peripheral speed of the roll while passing through a heated roll group at 85 ° C., and then the aqueous coating solution shown in Table 1 below was formed on one side of the longitudinally stretched film. A1 is applied (formation of the first application layer), and an aqueous coating solution B9 shown in the following Table 2 is applied to the opposite surface (formation of the second application layer), guided to a tenter stretching machine, and laterally at 100 ° C. After 4.0 times stretching and heat treatment at 230 ° C., a 2% relaxation treatment is performed in the transverse direction, the film thickness of the first coating layer (after drying) is 0.02 μm, and the film of the second coating layer A biaxially oriented polyethylene terephthalate film having a thickness of 50 μm and a coating layer having a thickness (after drying) of 0.02 μm was obtained.

  The film haze increase value (ΔH) by heat treatment of the obtained polyester film was small, and the precipitation amount of the ester cyclic trimer was small and good. Moreover, when the peeling force of the 2nd application layer was measured, it was 230 mN / cm and was favorable. The properties of this film are shown in Table 5 below.

Examples 2-24:
In Example 1, it manufactured like Example 1 except having changed an application agent composition into an application agent composition shown in Tables 1-3, and obtained a polyester film. As shown in Table 5, the finished polyester film had good film haze increase value (ΔH) by heat treatment and precipitation amount of ester cyclic trimer. Moreover, the peeling force of the 2nd application layer was also favorable.

Example 25:
Polyester (D) and (E) blended at a weight ratio of 80/20 as the surface layer and polyester (D) alone as the raw material for the intermediate layer were fed to the two extruders, respectively, at 285 ° C. After heating and melting, the layer A is the outermost layer (surface layer), the layer B is the intermediate layer, and the thickness composition ratio is A / B / A = 2.5 / 45/2 with two types and three layers (A / B / A). The film was coextruded so as to be .5 and cooled and solidified while being closely adhered to a mirror surface cooling drum having a surface temperature of 40 to 50 ° C. by using an electrostatic adhesion method, thereby preparing an unstretched polyethylene terephthalate film. The film was stretched 3.4 times in the longitudinal direction using the difference in peripheral speed of the roll while passing through a heated roll group at 85 ° C., and then the aqueous coating solution shown in Table 1 below was formed on one side of the longitudinally stretched film. A2 is applied (formation of the first application layer), and an aqueous coating solution B9 shown in Table 2 below is applied to the opposite surface (formation of the second application layer), and is led to a tenter stretching machine, at 100 ° C. in the transverse direction. After 4.0 times stretching and heat treatment at 230 ° C., a 2% relaxation treatment is performed in the transverse direction, the film thickness of the first coating layer (after drying) is 0.02 μm, and the film of the second coating layer A biaxially oriented polyethylene terephthalate film having a thickness of 50 μm and a coating layer having a thickness (after drying) of 0.02 μm was obtained.

  The film haze increase value (ΔH) by heat treatment of the obtained polyester film was small, and the precipitation amount of the ester cyclic trimer was small and good. Moreover, when the peeling force of the 2nd application layer was measured, it was 230 mN / cm and was favorable. The properties of this film are shown in Table 5 below.

Examples 26-30:
In Example 25, except having changed a coating agent composition into the coating agent composition shown to Tables 1-3, it manufactured like Example 25 and obtained the polyester film. As shown in Table 4, the finished polyester film had good film haze increase value (ΔH) by heat treatment and precipitation amount of ester cyclic trimer. Moreover, the peeling force of the 2nd application layer was favorable.

Comparative Examples 1-7:
In Example 1, except having changed a coating agent composition into the coating agent composition shown in Table 1, 2, and 4, it manufactured like Example 1 and obtained the polyester film. When the completed laminated polyester film was evaluated, as shown in Table 6 below, the film haze due to heat treatment was greatly increased, the ester cyclic trimer was much precipitated, and the peel strength of the second coating layer was poor. there were.

Comparative Example 8:
In Example 1, it manufactured similarly to Example 1 except not providing a 2nd coating layer, and obtained the polyester film. When the finished laminated polyester film was evaluated, the peel strength was poor and the releasability was poor.

Comparative Example 9:
In Example 1, it manufactured similarly to Example 1 except not providing a 1st coating layer, and obtained the polyester film. When the finished laminated polyester film was evaluated,
The film haze due to the heat treatment was greatly increased, and the ester cyclic trimer was often precipitated, and there was a concern about process contamination.

  The film of the present invention is a laminated polyester film having an excellent releasability as the deposition of the ester cyclic trimer is as small as possible even after the film is exposed to a high temperature atmosphere for a long time and undergoes a severe heat treatment step. For example, it can be suitably used as a substrate for process films used in various processes such as transfer for molding simultaneous transfer, process paper for manufacturing flexible printed wiring boards and plastic sheets.

Claims (2)

Having a coating layer formed from a coating solution containing a polyhydric aldehyde compound on one side of the polyester film and having a coating layer formed from a coating solution containing a release agent on the other side A laminated polyester film characterized. The laminated polyester film according to claim 1, wherein the coating liquid containing the polyvalent aldehyde compound contains at least one compound selected from the group consisting of an ammonium group-containing polymer, a crosslinking agent, and polyvinyl alcohol.