JP2016030378A - Laminate polyester film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminate polyester film that can highly suppress an oligomer from precipitating through a film surface when, for example, the film is exposed to high temperature, that has suitable water repellency to suppress water from remaining on the film in a cleaning process, and that has excellent adhesiveness to various functional layers.SOLUTION: The laminate polyester film includes a coating layer on at least one surface of a polyester film: the coating layer formed from a coating liquid that contains a crosslinking agent and a release agent and further contains other polymers by 30 wt.% or less as a nonvolatile component.SELECTED DRAWING: None

Description

  The present invention relates to a laminated polyester film, and more specifically, based on a polyester film, for example, less oligomer precipitation even after being exposed to high temperature, moderate water repellency and excellent adhesion to various functional layers It is related with the laminated polyester film which has.

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

  In particular, in recent years, it has been increasingly used instead of glass as a base material for a transparent conductive laminate, which is increasingly used for touch panels and the like. As such a transparent conductive laminate, there is one in which a polyester film is used as a base material and an ITO (indium tin oxide) film is formed by sputtering directly or via an anchor layer. Such a polyester film is generally heat-processed.

  In the manufacturing process of transparent electrodes for touch panels, many heating processes and chemicals, such as ITO crystallization process, resist printing process, edging process process, etc., which anneals transparent conductive film on which transparent conductive film made of ITO is formed It goes through the process. In such a transparent electrode manufacturing process, a surface protective film for a transparent conductive film is bonded to prevent the surface opposite to the surface on which the transparent conductive film is formed of the transparent conductive film from being stained or damaged. The polyester film is also used as the base material of the surface protective film.

  In the manufacturing process, for example, there are treatments such as leaving at 150 ° C. for 1 hour for low heat shrinkage (Patent Document 1) and performing heat treatment at 150 ° C. for ITO crystallization (Patent Document 2). .

  However, as a problem of polyester film, when exposed to such high temperature and long time treatment, oligomers (low molecular weight component of polyester, especially ester cyclic trimer) contained in the film are precipitated and crystallized on the film surface. As a result, deterioration of visibility due to whitening of the external appearance of the film, defects in post-processing, contamination of the process and members, and the like occur. Therefore, the characteristics of the transparent conductive laminate based on the polyester film cannot be said to be sufficiently satisfactory.

  As a measure for preventing oligomer precipitation, for example, it has been proposed to provide a curable resin layer made of a crosslinked product of a silicone resin and an isocyanate-based resin on a polyester film (Patent Document 3). 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 due to the coating layer, it is necessary to have a higher level of heat resistance than before and that the coating layer itself should have good oligomer precipitation prevention performance. is there.

  Furthermore, for example, in a polyester film used for a touch panel, a photoresist is laminated through an ITO film, and after patterning, a cleaning process is required to remove the photoresist, and residual water on the film is removed. May be a problem. Therefore, for the purpose of improving production efficiency, there is a demand for a film that can suppress residual water on the film after washing.

  In addition, polyester films used for touch panels are often hard-coated to prevent curling, improve scratch resistance, and improve performance such as surface hardness. Therefore, a polyester film having a coating layer excellent in adhesion with a hard coat may be required.

  Furthermore, when used as a surface protective film in a manufacturing process such as a touch panel, an adhesive layer or the like may be laminated on the film (Patent Document 3). Moreover, the transparent conductive film with which the transparent electrode pattern was formed on the laminated body by which two polyester films are bonded together is known. When used in a resistive film type touch panel, the two films are bonded via an adhesive layer, and the adhesive has cushioning properties, so pen input durability and surface pressure durability are improved (Patent Literature) 4). Furthermore, when used in a capacitive touch panel, the two films may be bonded together via a cured adhesive layer, which can improve touch sensitivity and suppress waviness (patent) Reference 5). Therefore, the polyester film which has the coating layer excellent in adhesiveness with an adhesive layer and a hardening adhesive bond layer is in the situation required.

JP 2007-42473 A JP 2007-200823 A JP 2011-63701 A JP 2009-76432 A JP 2013-94984 A

  The present invention has been made in view of the above circumstances, and the problem to be solved is to provide an optical laminated polyester film excellent in optical characteristics and visibility even after being processed as a product for optical members. Specifically, for example, in a severe condition such as a long-time heat treatment at 150 ° C., a sputtering process under a condition where high hearing is applied, and a durability test under a high-temperature and high-humidity atmosphere. Even after passing through the process, the increase in film haze is suppressed to a small level, and in order to suppress residual water on the film due to washing, it has moderate water repellency and is excellent for various functional layers. It is providing the laminated polyester film which has adhesiveness.

  As a result of intensive studies on the above problems, the present inventors have found that the above problems can be solved by a polyester film having a specific configuration, and have completed the present invention.

  That is, the gist of the present invention is that at least one side of a polyester film comprises a coating layer formed from a coating solution containing a crosslinking agent and a release agent and further containing 30% by weight or less of a polymer other than these as a non-volatile component. It exists in the laminated polyester film characterized by having.

  According to the laminated polyester film of the present invention, the oligomer precipitation from the surface is suppressed even after high-temperature and long-time treatment, so that a product having an excellent appearance without haze increase or generation of foreign matter can be obtained. Can do. In addition, it has excellent adhesion to hard coats, pressure-sensitive adhesive layers, and cured adhesive layers, and even when a cleaning process is required, it has moderate water repellency, so it provides a base film that suppresses residual water on the film. 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 the purpose.

  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 a polyester film is effectively suppressed, so that the polyester layer whose polyester cyclic trimer content of a polyester film is 0.7 weight% or less is thick. The film thickness of the polyester layer of 0.7% by weight or less 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 of 0.7% by weight or less is 1.5 μm or more, the heat treatment for a long time at 150 ° C., the sputtering process under high tension, Even when used in a processing step under severe conditions such as a durability test, the ester cyclic trimer is less likely to precipitate on the surface, and the increase in film haze can be further suppressed.

  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 preferably 3 μm or less, more preferably 0.02 μm to 2.8 μm, and even more preferably. It is in the range of 0.03 μm to 2.5 μm. If the average particle size is too large, the surface roughness of the film becomes too rough, or the particles easily fall off from the film surface.

  The particle content is preferably 3% by weight or less, more preferably 0.0003 to 1% by weight, and still more preferably 0.0005 to 0.5% by weight with respect to the polyester layer containing the particles. 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. Moreover, when there is too much particle content, the transparency of a film may be inadequate.

  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, ultraviolet absorbers, 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 preferably 10 to 300 μm, more preferably 15 to 250 μm, and still more preferably 20 to 200 μm. is there.

  In addition, it is preferable that the haze of the laminated polyester film obtained by this invention is 10% or less. More preferably, it is 5% or less, More preferably, it is 4% or less. If the haze of the laminated polyester film exceeds 10%, it may be difficult to use in appearance for optical film applications.

  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 base film and the coating layer are firmly adhered by stretching the film and the coating layer simultaneously. become. 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. 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.

  The coating layer of the present invention is formed from a coating solution containing, on at least one side of a polyester film, a crosslinking agent and a release agent, and a polymer other than these crosslinking agent and release agent as a non-volatile component ratio of 30% by weight or less. It is an essential requirement that The coating solution may contain other components.

  The coating solution containing 30% by weight or less of a polymer other than the crosslinking agent and the release agent is configured so that the crosslinking agent is a main component, although most of the coating solution is occupied by other materials. It is preferable. By occupying most of the crosslinking agent, a coating layer crosslinked at high density is formed, and precipitation of the ester cyclic trimer can be efficiently suppressed.

  As the crosslinking agent in the present invention, various known crosslinking agents can be used, and examples thereof include an oxazoline compound, a melamine compound, an epoxy compound, an isocyanate compound, a carbodiimide compound, and a silane coupling compound. Among these, especially when using for the use which provides a functional layer on a coating layer, an oxazoline compound is used suitably from a viewpoint that durable adhesiveness improves. 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 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 coating solution forming the 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 It is in the range of ˜8 mmol / g. By using it in the above range, the durability of the coating film is improved.

  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 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 compound is a carbodiimide equivalent (weight of carbodiimide compound to give 1 mol of carbodiimide group [g]), and is usually 100 to 1000, preferably 250 to 700, more preferably 300. It is in the range of ~ 500. 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 may be used singly or in combination of two or more types, but by combining two or more types, adhesion to the functional layer, which has been difficult to be compatible, and precipitation of the ester cyclic trimer after heating It has been found that the prevention is improved. Among them, the combination of an oxazoline compound that can improve adhesion to the functional layer and a melamine compound that is excellent in preventing precipitation of the ester cyclic trimer after heating is optimal and preferable.

  In addition, the present inventors have found that it is effective to combine three kinds of crosslinking agents in order to further improve the adhesion to the functional layer. As a combination of three or more kinds of crosslinking agents, it is optimal to select a melamine compound as one of the crosslinking agents. As a combination with the melamine compound, an oxazoline compound and an epoxy compound, a carbodiimide compound and an epoxy compound are used. Particularly preferred.

  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.

  In forming the coating layer of the film of the present invention, it is an essential requirement to use a release agent in combination from the viewpoint of imparting appropriate water repellency.

  The mold release agent used for forming the coating layer is used for improving the mold release property of the film, and is not particularly limited, and a conventionally known mold release agent can be used. For example, a long chain Examples thereof include an alkyl compound, a fluorine compound, a wax, and a silicone compound. Among these, a long-chain alkyl compound and a fluorine compound are preferable from the viewpoint that water repellency can be effectively obtained even in a small amount, and a long-chain alkyl compound is more preferable from the viewpoint of the appearance of the coating layer. 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 moderate water repellency can be effectively obtained 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, long chain alkyl group-containing isocyanates are preferable, and octadecyl isocyanate is particularly preferable in consideration of releasability and ease of handling.

  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 the long-chain alkyl compound which is mentioned later can also be used for a 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 3-11 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 later. Moreover, from a viewpoint of adhesiveness with a base material, it is more preferable that it is a polymer with vinyl chloride.

  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 addition, in the formation of the coating layer of the film of the present invention, a polymer can be used in combination for improving the coating appearance and improving the adhesion when a functional layer is formed on the coating layer. However, when the content is increased, the precipitation prevention property of the ester cyclic trimer after heating may be deteriorated.

  Specific examples of the polymer include polyester resin, acrylic resin, urethane resin, polyvinyl (polyvinyl alcohol, etc.), polyalkylene glycol, polyalkyleneimine, methylcellulose, hydroxycellulose, starches and the like. Among these, it is preferable to use a polyester resin, an acrylic resin, or a urethane resin from the viewpoint of improving adhesion with various surface functional layers.

  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 including acrylic and methacrylic monomers. These may be either homopolymers or copolymers, and copolymers with polymerizable monomers other than acrylic and methacrylic monomers. 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 in a polyester solution or a polyester dispersion is also included. Similarly, a polymer obtained by polymerizing a polymerizable monomer in a polyurethane solution or a polyurethane dispersion (sometimes a mixture of polymers) is also included. Similarly, a polymer (in some cases, a polymer mixture) obtained by polymerizing a polymerizable monomer in another polymer solution or dispersion is also included. Moreover, in order to improve adhesiveness more, it is also possible to contain a hydroxyl group and an amino group.

  The polymerizable monomer is not particularly limited, but particularly representative compounds include, for example, various carboxyl groups such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid, fumaric acid, maleic acid, and citraconic acid. Monomers, and salts thereof; such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, monobutyl hydroxyl fumarate, monobutyl hydroxy itaconate Various hydroxyl group-containing monomers; various (meth) acrylic acid esters such as methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, lauryl (meth) acrylate; (Meth) acrylamide, Various nitrogen-containing compounds such as acetone acrylamide, N-methylol acrylamide or (meth) acrylonitrile; various styrene derivatives such as styrene, α-methylstyrene, divinylbenzene, vinyltoluene, and various vinyls such as vinyl propionate Esters; various silicon-containing polymerizable monomers such as γ-methacryloxypropyltrimethoxysilane, vinyltrimethoxysilane, etc .; phosphorus-containing vinyl monomers; various vinyl halides such as vinyl chloride and biridene chloride 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.

  Among the above polyols, polycarbonate polyols and polyester polyols are more preferably used in order to improve adhesion to various topcoat layers.

  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, isoprobilitincyclohexyl-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, a self-emulsification type in which an ionic group is introduced into the structure of a urethane resin to form an ionomer is preferable because of excellent storage stability of the liquid and water resistance, transparency, and adhesion 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, and quaternary ammonium salt, and a carboxyl group is preferred. 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.

  Among the above-mentioned polymers, an acrylic resin is particularly preferable from the viewpoint of suppressing the precipitation of the ester cyclic trimer and achieving both high adhesion.

  In addition, particles can be used in combination for the purpose of blocking and improving slipperiness in forming the 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. Further, the lower limit is preferably 0.005 μm or more, more preferably 0.01 μm or more, 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.

  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 coating layer which comprises the laminated polyester film in this invention, the ratio of a crosslinking agent becomes like this. Preferably it is the range of 70-99.99 weight%, More preferably, it is 80-99. It is in the range of 5% by weight, more preferably in the range of 90 to 99% by weight. When the ratio is less than or equal to the above range, precipitation of the ester cyclic trimer after heating may not be effectively suppressed or adhesion may be deteriorated.

  The ratio of the release agent is preferably in the range of 0.01 to 30% by weight, more preferably 0.5 as the ratio to the total non-volatile components in the coating solution forming the coating layer constituting the laminated polyester film in the present invention. It is in the range of -15% by weight, more preferably in the range of 1-5% by weight. If the ratio is less than the above range, water repellency may not be sufficient. Moreover, when a ratio is more than the said range, adhesiveness with various topcoats may not be enough.

  As a ratio with respect to all the non-volatile components in the coating liquid which forms the coating layer which comprises the laminated polyester film in this invention, the ratio of polymers other than a crosslinking agent and a mold release agent is 30 weight% or less, Preferably it is 20 weight%. Hereinafter, it is more preferably 10% by weight or less, further preferably 3% by weight or less, and particularly preferably not contained. When a ratio exceeds the said upper limit, precipitation of the ester cyclic trimer after a heating cannot be suppressed effectively.

  From the viewpoint of preventing precipitation of the ester cyclic trimer after heating, when selecting a melamine compound as one of the crosslinking agents, the ratio of the melamine compound as a ratio to the total nonvolatile components in the coating liquid forming the coating layer, Preferably it is the range of 5-95 weight%, More preferably, it is the range of 10-90 weight%, More preferably, it is the range of 30-85 weight%. When the ratio is within the above range, precipitation of the ester cyclic trimer after heating can be effectively suppressed.

  From the viewpoint of coating appearance and adhesion, when an oxazoline compound is selected as one of the crosslinking agents, the ratio of the oxazoline compound is preferably 5 to 95% by weight as the ratio to the total nonvolatile components in the coating liquid forming the coating layer. %, More preferably in the range of 10 to 80% by weight, still more preferably in the range of 20 to 70% by weight. When the ratio is within the above range, when combined with other crosslinking agents, results excellent in coating appearance and adhesion can be obtained.

  The thickness of the coating layer is usually in the range of 0.003 μm to 1 μm, preferably 0.005 μm to 0.6 μm, more preferably 0.00 as the thickness of the coating layer on the finally obtained film. The range is from 01 μm to 0.4 μm. When the thickness is less than 0.003 μm, the amount of ester cyclic trimer precipitated from the film may not be sufficiently reduced. On the other hand, when it is thicker than 1 μm, 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 coating property 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.

  For the laminated polyester film in the present invention, for example, for a touch panel, a high degree of transparency may be required even after being exposed to a high temperature atmosphere for a long time. From this viewpoint, in order to cope with high transparency, the film haze change amount (ΔH) in the heat treatment (180 ° C., 30 minutes) is preferably 1.0% or less, more preferably 0.5% or less, More preferably, it is 0.3% or less. When ΔH exceeds 1.0%, the visibility decreases as the film haze increases due to precipitation of the ester cyclic trimer, and is not suitable for applications that require high visibility, such as for touch panels. It may be appropriate.

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 (180 ° C., 30 minutes) of the laminated polyester film in the present invention is preferably 1.3 mg / m ² or less, more preferably 0.8 mg / m ² or less, and even more preferably 0.6 mg / m ² or less. When the amount exceeds 1.3 mg / m ² , the amount of ester cyclic trimer deposited increases in the subsequent process, for example, with a long-time heat treatment in a high-temperature atmosphere such as 180 ° C. for 30 minutes. There is a concern that the performance may deteriorate or contamination of the process.

  Regarding the laminated polyester film in the present invention, for example, for touch panels, it is necessary to suppress the residual water on the film in the cleaning process for removing the photoresist after laminating the photoresist and patterning the ITO layer. is there. From this point of view, in order to cope with moderate water repellency, the water droplet contact angle is preferably 55 degrees or more, more preferably 65 degrees or more, and further preferably 70 degrees or more. If the water droplet contact angle is less than 55 degrees, residual water on the film cannot be effectively suppressed in the washing step, which may be inappropriate.

  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) Measuring method of contained ester cyclic trimer contained in polyester raw material:
About 200 mg of the polyester raw material is weighed and dissolved in 2 ml of a mixed solvent having a ratio of chloroform / HFIP (hexafluoro-2-isopropanol) of 3: 2. After dissolution, add 20 ml of chloroform, and then add 10 ml of methanol little by little. The precipitate is removed by filtration, and the precipitate is washed with a mixed solvent of chloroform / methanol ratio 2: 1. The filtrate / washing solution is collected, concentrated by an evaporator, and then dried. After the dried product was dissolved in 25 ml of DMF (dimethylformamide), this solution was supplied to liquid chromatography (“LC-7A” manufactured by Shimadzu Corporation) to determine the amount of ester cyclic trimer in DMF. The value is divided by the amount of the polyester raw material dissolved in the chloroform / HFIP mixed solvent to obtain the amount of ester cyclic trimer (weight%). The amount of 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 DMF accurately weighed.

The conditions for the liquid chromatograph were as follows.
Mobile phase A: Acetonitrile Mobile phase B: 2% acetic acid aqueous solution Column: “MCI GEL ODS 1HU” manufactured by Mitsubishi Chemical Corporation
Column temperature: 40 ° C
Flow rate: 1 ml / min Detection wavelength: 254 nm

(4) Calculation method of ester cyclic trimer contained in polyester film:
Calculation was based on the amount of ester cyclic trimer contained in the polyester raw material obtained by the method (3).

(5) 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.

(6) Film heat treatment method The sample measurement surface is exposed and fixed by being overlapped with Kent paper, and then left to stand at 180 ° C. for 30 minutes in a nitrogen atmosphere for heat treatment.

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

(8) Measurement of film haze increase (ΔH) by heat treatment First, a coating film comprising the following coating composition on the surface of the sample film opposite to the surface on which the coating layer of the present invention is provided is cured. Was applied to a thickness of 3 μm and dried in a hot air drying oven set at 80 ° C. for 1 minute. Next, using a high-pressure mercury lamp with an energy of 120 W / cm, irradiation for about 7 seconds at an irradiation distance of 100 mm, curing at 110 mJ / cm ² , and a laminated film provided with an active energy ray-curable resin layer on the film Obtained.
<< Coating composition >>
Nippon Gohsei Kagaku Kogyo Co., Ltd., Shigemitsu 7600B and Ciba Specialty Chemicals Co., Ltd. Irgacure 651 were mixed at a weight ratio of 100/5 and diluted with methyl ethyl ketone to a concentration of 30% by weight.
The haze of the obtained sample was measured by the method of item (7) (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 (6), and then the haze was measured by the method of (7) (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.

(9) Measurement of amount of ester cyclic trimer precipitated on the surface of the laminated polyester film The polyester film is heated in air at 180 ° C. for 30 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) is placed in the box prepared by the above method and left for 3 minutes, and then DMF is recovered. The recovered DMF was supplied to liquid chromatography (manufactured by Shimadzu Corporation: LC-7A) to determine the amount of ester cyclic trimer in DMF, and this value was divided by the film area in contact with DMF. The amount of ester cyclic trimer precipitated on the film surface (mg / m ² ) was used. The amount of ester cyclic trimer in DMF was calculated according to the absolute calibration curve method described in (3) Method for measuring amount of oligomer contained in polyester raw material.

(10) Adhesion evaluation method An active energy ray-curable resin composed of the following coating composition is applied to the coating film-forming surface of the polyester film, dried at 80 ° C for 1 minute to remove the solvent, and then from an ultraviolet irradiator. Ultraviolet rays were irradiated by a metal halide lamp 120W at 180 mJ / cm ² to form a hard coat layer having a thickness of 5 μm. 100 square cuts were made on the obtained film using a cutter guide having a gap interval of 1 mm. Next, an 18 mm wide tape (Cello Tape (registered trademark) CT-18 manufactured by Nichiban Co., Ltd.) was applied to the cut surface on the grid, and the 2.0 kg roller was reciprocated 20 times to completely adhere to it. Observe the peeled surface after abrupt peeling at the peeling angle. If the peeled area is less than 5%, ◎ if it is 5% or more but less than 20%, △ if it is 20% or more but less than 50%, △ if it is 50% or more. did.
<Active energy ray curable resin composition>
A mixed coating solution of 72 parts by weight of dipentaerythritol acrylate, 18 parts by weight of 2-hydroxy-3-phenoxypropyl acrylate, 1 part by weight of a photopolymerization initiator (Irgacure 651, manufactured by Ciba Specialty Chemicals), and 200 parts by weight of methyl ethyl ketone.

(11) Water droplet contact angle The contact angle was determined by the droplet method using a contact angle meter CA-D / A type manufactured by Kyowa Interface Science Co., Ltd. The water used was pure water purified with a MILLI-Q REAGENT-WATER-SYSTEM device manufactured by Nippon Millipore Corporation. The time from the dropping of the droplet to the measurement was about 30 seconds. Measurement was performed 6 times and the average value was adopted.

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 a polyester (A) ester cyclic trimer content of 0.61 and a 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 are added. Polyester (E) was obtained using the same method as the production method of polyester 1 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): Hexamethoxymethylol melamine (A2): Epocross which is an oxazoline compound (manufactured by Nippon Shokubai Co., Ltd.)
Oxazoline group amount 7.7 mmol / g
(A3): Epocross which is an oxazoline compound (manufactured by Nippon Shokubai Co., Ltd.)
Oxazoline group amount 4.5 mmol / g
(A4): Polyglycerol polyglycidyl ether

(A5): 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 (A6) obtained by adding 58.9 parts of n-butanol and maintaining the reaction liquid temperature at 80 ° C. for 2 hours and then adding 0.86 part of 2-ethylhexyl acid phosphate: polycarbodiimide system Carbodilite (Nisshinbo Chemical Co., Ltd.), a compound
Carbodiimide equivalent 340

(B1): 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. Then, after repeating the operation of adding methanol again for precipitation several times, the precipitate was washed with methanol, dried and ground, and then obtained.

(B2): An aqueous dispersion of a fluorine compound polymerized with the following composition: Octadecyl acrylate / perfluorohexyl ethyl methacrylate / vinyl chloride = 66/17/17 (wt%)
(B3): An emulsification facility having an internal capacity of 1.5 L equipped with a stirrer, thermometer, 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 Is passed under 400 atm and cooled to 40 ° C.

(C1): Aqueous dispersion of acrylic resin polymerized with the following composition: Emulsification weight of ethyl acrylate / n-butyl acrylate / methyl methacrylate / N-methylol acrylamide / acrylic acid = 65/21/10/2/2 (% by weight) Combined (emulsifier: anionic surfactant)
(C2): An aqueous dispersion of a polyester-based urethane resin formed from isophorone diisocyanate: terephthalic acid: isophthalic acid: ethylene glycol: diethylene glycol: dimethylolpropanoic acid = 12: 19: 18: 21: 25: 5 (mol%) (D1): 2-amino-2-methylpropanol hydrochloride (E1) which is a melamine crosslinking catalyst: silica particles having an average particle size of 0.07 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 in close contact with a mirror-cooled drum having a surface temperature of 45 ° C. by using an electrostatic contact 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. 1 was applied, led to a tenter stretching machine, stretched 4.0 times in the transverse direction at 100 ° C., heat treated at 230 ° C., and then subjected to a relaxation treatment of 2% in the transverse direction to obtain a film thickness of the coating layer. A biaxially oriented polyethylene terephthalate film having a film thickness of 125 μm having a coating layer of 0.04 μm (after drying) 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. Also, the adhesion was good. Furthermore, the water droplet contact angle was also high, and appropriate water repellency was exhibited. The properties of this film are shown in Table 3 below.

Examples 2-12:
In Example 1, it manufactured like Example 1 except having changed the coating composition into the coating composition shown in Table 1 and Table 2, and obtained the polyester film. The obtained polyester film had the characteristics shown in Table 3, the precipitation amount of the ester cyclic trimer by heat treatment was small, and the adhesion was good. In addition, the water contact angle was high and appropriate water repellency was exhibited.

Example 13:
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 = 1.5 / 22/1 with 2 types and 3 layers (A / B / A). The film was coextruded so as to be .5, and cooled and solidified while being in close contact with a mirror-cooled drum having a surface temperature of 45 ° C. by using an electrostatic contact 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. 9 is applied to a tenter stretching machine, stretched 4.0 times in the transverse direction at 100 ° C., further heat treated at 230 ° C., and then subjected to a relaxation treatment of 2% in the transverse direction to obtain a film thickness of the coating layer. A biaxially oriented polyethylene terephthalate film having a film thickness of 50 μm having a coating layer of 0.04 μm (after drying) was obtained.

  The resulting polyester film had a low film haze increase value (ΔH) due to heat treatment, a small amount of ester cyclic trimer precipitated, and good adhesion. Moreover, the water droplet contact angle was also high, and it showed moderate water repellency and was good. The properties of this film are shown in Table 3 below.

Example 14:
In Example 11, a polyester film was obtained in the same manner as in Example 11 except that the thickness was 125 μm and the thickness component ratio was changed to A / B / A = 5/115/5. Table 3 shows the properties of the obtained polyester film.

Example 15:
In Example 11, a polyester film was obtained in the same manner as in Example 11 except that the thickness was changed to 188 μm and the thickness component ratio was changed to A / B / A = 5/178/5. Table 3 shows the properties of the obtained polyester film.

Examples 16-23:
In Example 1, it manufactured similarly to Example 1 except having changed the coating agent composition into the coating agent composition shown in Table 1, and obtained the polyester film. The obtained polyester film had the characteristics shown in Table 3, the precipitation amount of the ester cyclic trimer by heat treatment was small, and the adhesion was good. Moreover, the water droplet contact angle was also high, moderate water repellency was exhibited, and it was good.

Comparative Examples 1-10:
In Example 1, it manufactured similarly to Example 1 except having changed the coating agent composition into the coating agent composition shown in Table 1, and obtained the polyester film. When the completed laminated polyester film was evaluated, as shown in Table 3, in Comparative Examples 1 to 4, the film haze by heat treatment increased greatly, precipitation of the ester cyclic trimer was large, and adhesion was poor. Comparative Examples 4 to 6 had a low water droplet contact angle and did not exhibit appropriate water repellency. In Comparative Examples 7 to 9, the film haze due to heat treatment is greatly increased, the precipitation of ester cyclic trimer is large, and Comparative Example 10 results in poor adhesion, and none of them can achieve all the performances. It was.

Comparative Example 11:
In Example 1, it manufactured like Example 1 except not providing an application layer, and obtained the polyester film. When the finished laminated polyester film was evaluated, the film haze due to heat treatment was greatly increased, and the precipitation of ester cyclic trimers was also large, and there was a concern about deterioration of visibility due to process contamination and whitening after heating. It was a thing. Also, the adhesion was poor.

  The film of the present invention is less exposed to ester cyclic trimer even after a harsh heat treatment process in which the film is exposed to a high temperature atmosphere for a long time, and has an appropriate water repellency and various top coats. As a laminated polyester film having excellent adhesion, for example, it can be suitably used as a base material of a transparent conductive laminate.

Claims (2)

A laminate characterized by having a coating layer formed from a coating solution containing a crosslinking agent and a release agent and further containing a polymer other than these as a non-volatile component in an amount of 30% by weight or less on at least one surface of the polyester film. Polyester film. The laminated polyester film according to claim 1, wherein the polyester film has at least one polyester layer having an ester cyclic trimer content of 0.7% by weight or less.