JP2015202681A - Surface protective film for electroconductive film, and transparent electroconductive base material film laminate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface protective film for electroconductive films, which is stuck to the electroconductive film when the electroconductive film is produced, is used when ITO (indium tin oxide) is crystallized, allows the amount of an oligomer to be deposited to be made smaller even when used in high-temperature treatment such as at an annealing step, and restrains the oligomer from contaminating a working environment or a product, and to provide a transparent electroconductive base material film laminate which is obtained by sticking the surface protective film for electroconductive films to a transparent electroconductive film base material.SOLUTION: The surface protective film for electroconductive films is obtained by forming a coating layer on at least one surface of a laminated polyester film and is characterized in that when the surface protective film for electroconductive films is heated at 150°C for 90 minutes, the amount of an ester cyclic trimer to be deposited on the surface of the coating layer is 1.2 mg/mor smaller. The transparent electroconductive base material film laminate is obtained by sticking the surface protective film for electroconductive films to the transparent electroconductive film base material.

Description

  Even if this invention is used for the heat processing used at the time of manufacturing an electroconductive film at high temperature, there is little precipitation amount of an oligomer and it can suppress that an oligomer contaminates the surrounding work environment and a product. The present invention relates to a surface protective film for a conductive film and a transparent conductive base film laminate.

  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 transparent conductive laminates, which are increasingly used for touch panels, electronic papers, and the like. As such a transparent conductive laminate, there is one in which a biaxially stretched 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. The biaxially stretched polyester film used is generally heat processed.

  In the process of manufacturing a transparent electrode for a touch panel, a transparent conductive film on which a transparent conductive film made of ITO is formed is subjected to many heating processes such as an ITO crystallization process, a resist printing process, and an edging process. Go through the chemical treatment process. In such a transparent electrode manufacturing process, a surface protective film for a transparent conductive film is bonded to prevent the side opposite to the surface on which the transparent conductive film of the transparent conductive film is formed from being stained or damaged. Used.

  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). Therefore, the surface protection film for transparent conductive film is required to have heat resistance.

  However, as a problem of the polyester film used as the base material, when exposed to such high temperature and long time treatment, the oligomer (low molecular weight component of polyester, especially ester cyclic trimer) contained in the film is Precipitation and crystallization cause deterioration of visibility due to whitening of the film appearance, defects in post-processing, contamination of the process and members, and the like. 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.

JP 2007-42473 A JP 2007-200823 A JP 2007-320144 A

  The present invention has been made in view of the above circumstances, and a solution to the problem is that it is used by laminating at the time of producing a conductive film, and further used for crystallization of ITO (indium tin oxide). Even if it is used for heat treatment at a high temperature such as a process, the amount of oligomer precipitation is small, and the surface protective film for a conductive film capable of suppressing the oligomer from contaminating the surrounding work environment and product, and It is providing the laminated transparent conductive base film laminated body.

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

That is, the gist of the present invention is that the laminated polyester film has a coating layer on at least one surface, and when heated at 150 ° C. for 90 minutes, the precipitation amount of ester cyclic trimer on the coating layer surface is 1.2 mg / m ² or less. A surface protective film for a conductive film, and a transparent conductive substrate film laminate comprising a laminate of the surface protective film for a conductive film and a transparent conductive film substrate Exist.

  According to the present invention, it is used for crystallization of ITO (indium tin oxide), and even when used in a heat treatment at a high temperature, for example, an annealing step, the oligomer is prevented from depositing on the surface, and the oligomer Can prevent contamination of the surrounding work environment and product, and the transparent conductive substrate film laminate formed by bonding the surface protective film of the present invention protects from contamination, dents, scratches, etc. Therefore, the workability and the production efficiency can be improved, so that the industrial value of the present invention is high.

  The polyester in the present invention is a conventionally known method, for example, a method of directly obtaining a low-polymerization degree polyester by reaction of a dicarboxylic acid and a diol, or a lower alkyl ester of a dicarboxylic acid and a diol reacted with a conventionally known transesterification catalyst. Then, it can obtain by the method of performing a polymerization reaction in presence of a polymerization catalyst. As the polymerization catalyst, a known catalyst such as an antimony compound, a germanium compound, or a titanium compound may be used. Preferably, the amount of the antimony compound is zero or antimony is reduced to 100 ppm or less to reduce film dullness. .

  The polyester may be converted into chips after melt polymerization, and further subjected to solid phase polymerization as necessary under heating under reduced pressure or in an inert gas stream such as nitrogen. The intrinsic viscosity of the obtained polyester is preferably 0.40 dl / g or more, and preferably 0.40 to 0.90 dl / g.

  You may mix | blend particle | grains in the polyester layer in the film of this invention with the main objective of providing easy slipperiness. The kind of the particle to be blended is not particularly limited as long as it is a particle capable of imparting slipperiness. Specific examples thereof include silica, calcium carbonate, magnesium carbonate, barium carbonate, calcium sulfate, calcium phosphate, and phosphoric acid. Examples thereof include particles of magnesium silicon oxide, kaolin, aluminum oxide, titanium oxide and the like. Further, the heat-resistant organic particles described in JP-B-59-5216, JP-A-59-217755 and the like may be used. Examples of other heat-resistant organic particles include thermosetting urea resins, thermosetting phenol resins, thermosetting epoxy resins, benzoguanamine resins, and the like. Furthermore, 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.

  Moreover, the average particle diameter of the particle | grains to be used is 0.01-5 micrometers normally, Preferably it is the range of 0.03-2.5 micrometers. If the average particle size is less than 0.01 μm, the particles tend to aggregate and the dispersibility may be insufficient. On the other hand, if the average particle size exceeds 5 μm, the surface roughness of the film becomes too rough and transparent. May become inferior, or the particles may easily fall off the film surface.

  Furthermore, the particle content in the polyester is usually 3% by weight or less, preferably 0.0003 to 1.0% by weight, more preferably 0.0005 to 0.5% by weight, based on the total polyester constituting the film. It is a range. When there are no or few particles, the transparency of the film will be high and a good film will be obtained, but the depletion property may be insufficient. In some cases, it is necessary to improve the performance. When the particle content exceeds 3% by weight, the transparency of the film may be insufficient.

  The method for adding particles to the polyester 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, but the polycondensation reaction may proceed preferably after the esterification stage or after the transesterification reaction. Also, a method of blending a slurry of particles dispersed in ethylene glycol or water with a vented kneading extruder and a polyester raw material, or a blending of dried particles and a polyester raw material using a kneading extruder. It is done by methods.

  In addition to the above-mentioned particles, conventionally known antioxidants, heat stabilizers, lubricants, antistatic agents, fluorescent brighteners, dyes, pigments, and the like are added to the polyester film in the present invention as necessary. be able to. Depending on the application, an ultraviolet absorber, particularly a benzoxazinone-based ultraviolet absorber, may be contained.

  For example, the polyester film of the present invention must have a multilayer structure composed of two or three layers or three or three layers. In the case of a single-layer film, since the melt viscosity of the raw material used is high, the amount of extrusion is limited and productivity is lowered. 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, which is an essential condition for the present invention.

  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 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 10 to 250 μm, preferably 23 to 125 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 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 constituting the surface protective film in the present invention has good adhesion to the adhesive layer, and the film haze increases even after heat treatment in a high-temperature atmosphere (for example, 150 ° C., 90 minutes). It is preferable to be as small as possible.

  For the formation of the coating layer of the film of the present invention, a crosslinking agent is used for the purpose of preventing precipitation of the ester cyclic trimer and improving the durability and coating properties of the coating layer. Various known crosslinking agents can be used as the crosslinking agent, and examples thereof include oxazoline compounds, melamine compounds, epoxy compounds, isocyanate compounds, carbodiimide compounds, and silane coupling compounds. Among these, especially when using for the use which provides a functional layer on a coating layer, an oxazoline compound and an epoxy compound are 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 the 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 carbodiimide equivalent (weight of the 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 a functional layer (various top coats such as pressure-sensitive adhesive) and heating have been difficult. It was found that the precipitation prevention property of the subsequent ester cyclic trimer was 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.

  Moreover, in order to improve the adhesiveness with a functional layer more, it discovered that it was effective to combine three types of crosslinking agents. 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 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.

  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. However, when the content increases, the precipitation prevention property of the ester cyclic trimer after heating may deteriorate, and it is usually 30% by weight or less, preferably 20% by weight or less, more preferably 10% by weight or less. When the ratio exceeds the above range, precipitation of the ester cyclic trimer after heating may not be effectively suppressed.

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 0.01 μm or more, more preferably 0.03 μm or more, and particularly preferably a range 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.

  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 non-volatile components in the coating liquid forming the coating layer constituting the laminated polyester film in the present invention, the ratio of the crosslinking agent is usually 70% by weight or more, preferably 80% by weight or more, more preferably 90% by weight. That's it. When the ratio is less than the above range, precipitation of the ester cyclic trimer after heating may not be effectively suppressed.

  From the viewpoint of preventing precipitation of the ester cyclic trimer after heating, when melamine is selected as one of the cross-linking agents, the ratio of melamine is usually 5 as a ratio to the total nonvolatile components in the coating liquid forming the coating layer. It is in the range of -95% by weight, preferably in the range of 15-80% by weight, particularly preferably in the range of 30-65% by weight. When the ratio is less than the above range, precipitation of the ester cyclic trimer after heating may not be effectively suppressed. When the ratio is not less than the above range, the appearance of coating may be deteriorated.

  The thickness of the coating layer is usually in the range of 0.003 μm to 1 μm, preferably 0.005 μm to 0.5 μm, more preferably 0.00 as the thickness of the coating layer on the finally obtained film. It is in the range of 01 μm to 0.2 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 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 0.3% 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.

Moreover, from the viewpoint of the precipitation amount of the ester cyclic trimer, the amount of the ester cyclic trimer extracted from the film surface with dimethylformamide by heat treatment (150 ° C., 90 minutes) is 1. 2 mg / m ² or less, more preferably 1.0 mg / m ² or less. If it exceeds 0.8 mg / m ² , the amount of ester cyclic trimer deposited increases in the subsequent process, for example, with long-term heat treatment at 150 ° C. for 90 minutes, etc., and the film becomes transparent. There is a problem that processability is deteriorated and process contamination.

  Hereinafter, although the manufacturing method of the polyester film of this invention is demonstrated concretely, as long as the summary of this invention is satisfied, this invention is not specifically limited to the following illustrations.

  First, a dried or undried polyester chip by a known method is supplied to a melt extrusion apparatus and heated to a temperature equal to or higher than the melting point of each polymer and melted. Next, the molten polymer is extruded from a die and rapidly cooled and solidified on a rotary cooling drum so that the temperature is equal to or lower than the glass transition temperature to obtain a substantially amorphous unoriented sheet. In this case, in order to improve the flatness of the sheet, it is preferable to improve the adhesion between the sheet and the rotary cooling drum. In the present invention, an electrostatic application adhesion method and / or a liquid application adhesion method is preferably employed.

  In the present invention, as described above, two or more polyester melt extruders can be used to form a laminated film of two layers or three or more layers by a so-called coextrusion method. As the layer structure, an A / B structure using an A raw material and a B raw material, or an A / B / A structure, and further using a C raw material to form an A / B / C structure or other film. Can do. For example, the surface shape of the A layer can be designed using specific particles as the A raw material, and a film having an A / B or A / B / A structure can be formed using a raw material not containing particles as the B raw material. In this case, since the raw material of B layer can be selected freely, a cost advantage etc. are large. Further, even if the recycled material of the film is blended with the B layer, the surface roughness can be designed by the surface A layer, so that the cost advantage is further increased.

  The coating layer may be formed only on one side of the polyester film or on both sides. When formed only on one side, other characteristics can be imparted by forming a coating layer different from the above-mentioned coating layer on the opposite surface as necessary. In addition, in order to improve the applicability | paintability and adhesiveness to the film of a coating agent, you may give a chemical process and an electrical discharge process to a film before application | coating. Further, in order to further improve the surface characteristics, a discharge treatment may be performed after the coating layer is formed.

  Next, the pressure-sensitive adhesive layer constituting the surface protective film in the present invention will be described below.

  In the surface protective film in the present invention, it is an essential requirement to provide an adhesive layer on one coating layer surface.

  By adopting the above configuration, the characteristics of the coating layer are utilized, and the film surface is protected by the coating layer having high heat resistance even when the film surface is exposed to a severe heat treatment process for a long time. Precipitation can be suppressed.

  The pressure-sensitive adhesive layer in the present invention means a layer composed of an adhesive material, and a conventionally known material such as a silicone pressure-sensitive adhesive or an acrylic pressure-sensitive adhesive is used within a range not impairing the gist of the present invention. it can. In the present invention, as one specific example, the case where an acrylic pressure-sensitive adhesive is used will be described below.

  In the present invention, the acrylic pressure-sensitive adhesive means a pressure-sensitive adhesive layer containing, as a base polymer, an acrylic polymer formed using an acrylic monomer as an essential monomer component. The acrylic polymer has (meth) acrylic acid alkyl ester and / or (meth) acrylic acid alkoxyalkyl ester having a linear or branched alkyl group as an essential monomer component (more preferably as a main monomer component). ) It is preferably an acrylic polymer to be formed. Further, the acrylic polymer is particularly preferably an acrylic polymer formed using (meth) acrylic acid alkyl ester and acrylic acid alkoxyalkyl ester having a linear or branched alkyl group as essential monomer components. That is, the pressure-sensitive adhesive layer of the present invention is an acrylic pressure-sensitive adhesive layer formed using (meth) acrylic acid alkyl ester and acrylic acid alkoxyalkyl ester having a linear or branched alkyl group as essential monomer components. It is particularly preferred.

  In addition, the monomer component forming the acrylic polymer that is the base polymer in the pressure-sensitive adhesive layer of the present invention further contains a polar group-containing monomer, a polyfunctional monomer, and other copolymerizable monomers. It may be contained as a polymerization monomer component.

  In addition, said "(meth) acryl" represents "acryl" and / or "methacryl", and others are the same. Further, although not particularly limited, the content of the acrylic polymer as the base polymer in the pressure-sensitive adhesive layer of the present invention is preferably 60% by weight or more, more preferably based on the total weight (100% by weight) of the pressure-sensitive adhesive layer. 80% by weight or more.

  As an essential monomer component for forming the acrylic polymer, a (meth) acrylic acid alkyl ester having a linear or branched alkyl group (hereinafter simply referred to as “(meth) acrylic acid alkyl ester”) may be used. ) Can be suitably used. Specific examples of the (meth) acrylic acid alkyl ester include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, (meth ) Isobutyl acrylate, s-butyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, isopentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate , Octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, (meth) acrylic acid Isodecyl, undecyl (meth) acrylate, dodecyl (meth) acrylate, (Meth) acrylic acid tridecyl, (meth) acrylic acid tetradecyl, (meth) acrylic acid pentadecyl, (meth) acrylic acid hexadecyl, (meth) acrylic acid heptadecyl, (meth) acrylic acid octadecyl, (meth) acrylic acid nonadecyl, (meta ) (Meth) acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group such as eicosyl acrylate. Moreover, the (meth) acrylic acid alkyl ester may be used alone or in combination of two or more. Among them, (meth) acrylic acid alkyl ester having 2 to 14 carbon atoms in the alkyl group is preferable, and (meth) acrylic acid alkyl ester having 2 to 10 carbon atoms in the alkyl group is more preferable. In particular, 2-ethylhexyl acrylate (2EHA) is preferable.

  Moreover, (meth) acrylic acid alkoxyalkyl ester [alkoxyalkyl (meth) acrylate] can also be suitably used as the essential monomer component (more preferably, the main monomer component) for forming the acrylic polymer. Particularly preferred is an acrylic acid alkoxyalkyl ester [alkoxyalkyl acrylate]. Although it does not specifically limit as (meth) acrylic-acid alkoxyalkylester, For example, (meth) acrylic-acid 2-methoxyethyl, (meth) acrylic-acid 2-ethoxyethyl, (meth) acrylic-acid methoxytriethylene glycol, (meta ) 3-methoxypropyl acrylate, 3-ethoxypropyl (meth) acrylate, 4-methoxybutyl (meth) acrylate, 4-ethoxybutyl (meth) acrylate, and the like. The said (meth) acrylic-acid alkoxyalkylester can be used individually or in combination of 2 or more types. Among these, 2-methoxyethyl acrylate (2MEA) is preferable.

  In addition, the content of the essential monomer component [(meth) acrylic acid alkyl ester and / or (meth) acrylic acid alkoxyalkyl ester] forming the above acrylic polymer is selected from the viewpoint of adhesiveness of the pressure-sensitive adhesive layer. The amount is preferably 5% by weight or more (for example, 5 to 100% by weight), more preferably 5 to 95% by weight, based on the total amount (100% by weight) of monomer components forming the polymer. In addition, when both (meth) acrylic acid alkyl ester and (meth) acrylic acid alkoxyalkyl ester are used as monomer components, the content of (meth) acrylic acid alkyl ester and (alkyl) alkoxyalkyl (meth) acrylate The total amount of ester content (total content) only needs to satisfy the above range.

  Among the above, it is preferable that both (meth) acrylic acid alkyl ester and acrylic acid alkoxyalkyl ester are used as essential monomer components for forming the acrylic polymer. In that case, the content of the (meth) acrylic acid alkyl ester is preferably 5 to 95% by weight, more preferably 10 to 90% by weight, based on the total amount of monomer components (100% by weight) forming the acrylic polymer. %, More preferably 65-80% by weight, most preferably 65-75% by weight. If the content exceeds 95% by weight, the adhesiveness may decrease, and if it is less than 5% by weight, the elastic modulus of the pressure-sensitive adhesive layer may be too high. Further, the content of the alkoxyalkyl ester of acrylic acid is preferably 10 to 45% by weight, more preferably 10 to 40% by weight, and still more preferably with respect to the total amount (100% by weight) of monomer components forming the acrylic polymer. 20 to 35% by weight. If the content exceeds 45% by weight, the elastic modulus of the pressure-sensitive adhesive layer may be too high, and if it is less than 10% by weight, the adhesiveness may decrease.

  Examples of the polar group-containing monomer include (meth) acrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, isocrotonic acid and other carboxyl group-containing monomers or anhydrides thereof (maleic anhydride, etc. ); Hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and 6-hydroxyhexyl (meth) acrylate Hydroxyl group (hydroxyl group) -containing monomers such as vinyl alcohol and allyl alcohol; (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N-methylol (meth) acrylamide, N-methoxymethyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide, N-hydro Amide group-containing monomers such as ethyl acrylamide; Amino group-containing monomers such as aminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, and t-butylaminoethyl (meth) acrylate; ) Glycidyl group-containing monomers such as glycidyl acrylate and methyl glycidyl (meth) acrylate; Cyano group-containing monomers such as acrylonitrile and methacrylonitrile; N-vinyl-2-pyrrolidone, (meth) acryloylmorpholine , N-vinyl pyridine, N-vinyl piperidone, N-vinyl pyrimidine, N-vinyl piperazine, N-vinyl pyrrole, N-vinyl imidazole, N-vinyl oxazole and other heterocyclic ring-containing vinyl monomers; sodium vinyl sulfonate, etc. Sulfonic acid group-containing monomer of 2-hydroxyethyl Chestnut phosphoric acid group-containing monomers such as acryloyl phosphate; cyclohexyl maleimide, imide group-containing monomers such as isopropyl maleimide; 2-methacryloyloxy such acryloyl isocyanate group-containing monomers such as methacryloyloxyethyl isocyanate. The polar group-containing monomers can be used alone or in combination of two or more. Among the above-mentioned polar group-containing monomers, carboxyl group-containing monomers or acid anhydrides thereof, hydroxyl group-containing monomers, amino group-containing monomers, amide group-containing monomers, heterocyclic-containing vinyls Monomers are preferable, and acrylic acid (AA), 4-hydroxybutyl acrylate (4HBA), N-vinyl-2-pyrrolidone (NVP), and N-hydroxyethylacrylamide (HEAA) are particularly preferable.

  The content of the polar group-containing monomer is preferably 15% by weight or less with respect to 100% by weight of the monomer component forming the acrylic polymer. When it exceeds 15% by weight, the cohesive force of the pressure-sensitive adhesive layer becomes too high. As a result, the storage elastic modulus (23 ° C.) becomes too high, and the stress relaxation property may be lowered. If it is less than 0.01% by weight, the adhesion may be lowered.

  Among the above, the content of the hydroxyl group-containing monomer is preferably 5% by weight or less with respect to 100% by weight of the monomer component forming the acrylic polymer. When the content exceeds 5% by weight, the cohesive force of the pressure-sensitive adhesive layer becomes too high, the storage elastic modulus (23 ° C.) becomes too high, and the stress relaxation property may be lowered. Content of polar group-containing monomers other than hydroxyl group-containing monomers (particularly carboxyl group-containing monomers, amide group-containing monomers, amino group-containing monomers, heterocyclic-containing vinyl monomers) Is preferably 15% by weight or less with respect to 100% by weight of the monomer component forming the acrylic polymer. When the content exceeds 15% by weight, the cohesive force of the pressure-sensitive adhesive layer becomes too high, the storage elastic modulus (23 ° C.) becomes too high, and the stress relaxation property may be lowered.

  Examples of the polyfunctional monomer include hexanediol di (meth) acrylate, butanediol di (meth) acrylate, (poly) ethylene glycol di (meth) acrylate, and (poly) propylene glycol di (meth) acrylate. , Neopentyl glycol di (meth) acrylate, pentaerythritol di (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, trimethylolpropane tri (meth) acrylate, tetramethylol methanetri (meth) ) Acrylate, allyl (meth) acrylate, vinyl (meth) acrylate, divinylbenzene, epoxy acrylate, polyester acrylate, urethane acrylate and the like. The said polyfunctional monomer can be used individually or in combination of 2 or more types. Among the above, as the polyfunctional monomer, trimethylolpropane triacrylate (TMPTA) is preferable.

  The content of the polyfunctional monomer is preferably 0.5% by weight or less with respect to 100% by weight of the total amount of monomer components forming the acrylic polymer. When the content exceeds 0.5% by weight, for example, the cohesive force of the pressure-sensitive adhesive layer becomes too high, and the stress relaxation property may be lowered.

  Examples of copolymerizable monomers (other copolymerizable monomers) other than the above polar group-containing monomers and polyfunctional monomers include cyclopentyl (meth) acrylate and cyclohexyl (meth). (Meth) acrylates having an alicyclic hydrocarbon group such as acrylate and isobornyl (meth) acrylate, and (meth) acrylates having an aromatic hydrocarbon group such as phenyl (meth) acrylate and the like (meth ) (Meth) acrylic acid esters other than alkyl acrylates, alkoxyalkyl (meth) acrylates, polar group-containing monomers and polyfunctional monomers; vinyl esters such as vinyl acetate and vinyl propionate; styrene , Aromatic vinyl compounds such as vinyl toluene; ethylene, butadiene, isoprene, isobutylene, etc. Olefins or dienes; vinyl ethers such as vinyl alkyl ethers; and vinyl chloride.

  The acrylic polymer can be prepared by polymerizing the above monomer components by a conventionally known or conventional polymerization method. Examples of the polymerization method of the acrylic polymer include a solution polymerization method, an emulsion polymerization method, a bulk polymerization method, and a polymerization method by active energy ray irradiation (active energy ray polymerization method). Among them, the solution polymerization method and the active energy ray polymerization method are preferable in terms of transparency, water resistance, production cost and the like, and particularly when forming a relatively thick pressure-sensitive adhesive layer, active energy ray polymerization (photopolymerization and Method), and an ultraviolet polymerization method by ultraviolet irradiation is particularly preferable.

  Examples of the active energy rays irradiated in the above active energy ray polymerization (photopolymerization) include ionizing radiation such as α rays, β rays, γ rays, neutron rays, electron rays, and ultraviolet rays, among others. Ultraviolet rays are suitable for the use of the present invention. Further, the irradiation energy, irradiation time, irradiation method, and the like of the active energy ray are not particularly limited as long as they do not impair the gist of the present invention.

  In the solution polymerization, various common solvents can be used. Examples of such solvents include esters such as ethyl acetate and n-butyl acetate; aromatic hydrocarbons such as toluene and benzene; aliphatic hydrocarbons such as n-hexane and n-heptane; cyclohexane and methylcyclohexane Organic solvents such as ketones such as methyl ethyl ketone and methyl isobutyl ketone. A solvent can be used individually or in combination of 2 or more types.

  In preparing the acrylic polymer, a polymerization initiator such as a thermal polymerization initiator or a photopolymerization initiator (photoinitiator) can be used depending on the type of polymerization reaction. A polymerization initiator can be used individually or in combination of 2 or more types.

  The photopolymerization initiator is not particularly limited. For example, benzoin ether photopolymerization initiator, acetophenone photopolymerization initiator, α-ketol photopolymerization initiator, aromatic sulfonyl chloride photopolymerization initiator, photo An active oxime photopolymerization initiator, a benzoin photopolymerization initiator, a benzyl photopolymerization initiator, a benzophenone photopolymerization initiator, a ketal photopolymerization initiator, a thioxanthone photopolymerization initiator, and the like can be used. The amount of the photopolymerization initiator used is not particularly limited, but is preferably in the range of 0.01 to 0.2 parts by weight with respect to 100 parts by weight of the total amount of monomer components forming the acrylic polymer.

Specific examples of the benzoin ether photopolymerization initiator include, for example, benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2,2-dimethoxy-1,2-diphenylethane-1-one. And anisole methyl ether. Examples of the acetophenone photopolymerization initiator include 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexyl phenyl ketone, 4-phenoxydichloroacetophenone, and 4- (t-butyl). Examples include dichloroacetophenone. Examples of the α-ketol photopolymerization initiator include 2-methyl-2-hydroxypropiophenone and 1- [4- (2-hydroxyethyl) phenyl] -2-methylpropan-1-one. . Specific examples of the aromatic sulfonyl chloride photopolymerization initiator include 2-naphthalenesulfonyl chloride. Examples of the photoactive oxime photopolymerization initiator include 1-phenyl-1,1-propanedione-2- (o-ethoxycarbonyl) -oxime. Examples of the benzoin photopolymerization initiator include benzoin. Examples of the benzyl photopolymerization initiator include benzyl.
Specific examples of the benzophenone photopolymerization initiator include benzophenone, benzoylbenzoic acid, 3,3′-dimethyl-4-methoxybenzophenone, polyvinylbenzophenone, α-hydroxycyclohexyl phenyl ketone, and the like. Specific examples of the ketal photopolymerization initiator include benzyldimethyl ketal. Specific examples of the thioxanthone photopolymerization initiator include thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-diisopropylthioxanthone, dodecylthioxanthone, and the like.

Specific examples of the thermal polymerization initiator include azo polymerization initiators [for example, 2,2′-azobisisobutyronitrile, 2,2′-azobis-2-methylbutyronitrile, 2,2′-azobis. (2-methylpropionic acid) dimethyl, 4,4′-azobis-4-cyanovaleric acid, azobisisovaleronitrile, 2,2′-azobis (2-amidinopropane) dihydrochloride, 2,2′-azobis [ 2- (5-methyl-2-imidazolin-2-yl) propane] dihydrochloride, 2,2′-azobis (2-methylpropionamidine) disulfate, 2,2′-azobis (N, N′-di) Methyleneisobutylamidine) dihydrochloride], peroxide-based polymerization initiators (eg, dibenzoyl peroxide, tert-butylpermaleate, etc.), redox Scan type polymerization initiators and the like. The amount of the thermal polymerization initiator used is not particularly limited as long as it does not impair the gist of the present invention, and may be any range that can be conventionally used as a thermal polymerization initiator.

  In the pressure-sensitive adhesive layer used in the present invention, a crosslinking agent, a crosslinking accelerator, a tackifier (for example, rosin derivative resin, polyterpene resin, petroleum resin, oil-soluble phenol resin, etc.), anti-aging agent, and filling are added as necessary. Agents, colorants (pigments, dyes, etc.), UV absorbers, antioxidants, chain transfer agents, plasticizers, softeners, surfactants, antistatic agents, etc., as necessary within the range that does not impair the properties of the present invention. Can be used.

  The said crosslinking agent can control the gel fraction of an adhesive layer by bridge | crosslinking the base polymer of an adhesion layer. As crosslinking agents, isocyanate crosslinking agents, epoxy crosslinking agents, melamine crosslinking agents, peroxide crosslinking agents, urea crosslinking agents, metal alkoxide crosslinking agents, metal chelate crosslinking agents, metal salt crosslinking agents Agents, carbodiimide crosslinking agents, oxazoline crosslinking agents, aziridine crosslinking agents, amine crosslinking agents, and the like, and isocyanate crosslinking agents and epoxy crosslinking agents can be preferably used. A crosslinking agent can be used individually or in combination of 2 or more types.

  The thickness (after drying) of the pressure-sensitive adhesive layer of the surface protective film in the present invention is usually 10 μm to 200 μm, preferably 20 μm to 150 μm, and more preferably 25 μm to 100 μm. When the thickness of the adhesive layer (after drying) is less than 10 μm, it may be difficult to obtain a desired adhesive force. On the other hand, when the pressure-sensitive adhesive layer thickness (after drying) exceeds 200 μm, the pressure-sensitive adhesive layer may be insufficiently cured, resulting in problems such as workability deterioration.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to a following example, unless the summary is exceeded. The measuring method used in the present invention is as follows.

(1) Measurement of Intrinsic Viscosity of Polyester 1 g of polyester was accurately weighed and dissolved by adding 100 ml of a mixed solvent of phenol / tetrachloroethane = 50/50 (weight ratio), and measured at 30 ° C.

(2) Measuring method of average particle diameter (d50: μm) Integration (weight basis) 5 in equivalent spherical distribution measured using centrifugal sedimentation type particle size distribution measuring device (SA-CP3 type manufactured by Shimadzu Corporation) 5

(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) Heat treatment method of film The sample was measured by exposing it to the Kent paper and fixed, and left to stand at 150 ° C. for 90 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 (8), 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 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) 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 After applying an active energy ray-curable resin composed of the following coating composition on the coating film-forming surface of the polyester film with a # 16 wire bar and drying at 80 ° C. for 1 minute to remove the solvent. Then, 180 mJ / cm ^{2 was} irradiated with ultraviolet rays from an ultraviolet irradiator with a metal halide lamp 120W to form a 5 μm thick hard coat layer. 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.

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 0.04 part of ethyl acid phosphate was added to this reaction mixture, 0.03 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 0.68 due to a change in stirring power of the reaction vessel, 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)>
Polyester (A) is used as a starting material, and is continuously fed into a stirring crystallization machine maintained at about 160 ° C. in a nitrogen atmosphere so that the residence time is about 60 minutes. Continuously supplied to a solid phase polycondensation apparatus, and at 215 ° C. in a nitrogen atmosphere, the residence time was adjusted so that the intrinsic viscosity of the resulting polyethylene terephthalate resin was 0.82, and solid phase polycondensation was performed. ) The obtained polyester (B) had an intrinsic viscosity of 0.82 and an ester cyclic trimer content of 0.46% by weight.

<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) is used as a starting material, 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 of polyester (D) was obtained.

<Method for producing polyester (E)>
In the production method of polyester 1, after adding 0.04 part of ethyl acid phosphate, 0.3 part of silica particles having an average particle diameter (d50) of 1.6 μm dispersed in ethylene glycol and 0.03 part of antimony trioxide are added. Polyester (E) was obtained using the same method as the production method of polyester 1 except that the polycondensation reaction was stopped at the time corresponding to the intrinsic viscosity of 0.66. The obtained polyester (E) had an intrinsic viscosity of 0.66 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): Epocros (made by Nippon Shokubai Co., Ltd.) which is an oxazoline compound. Oxazoline group amount 7.7 mmol / g.
(A3): Epocros (made by Nippon Shokubai Co., Ltd.) which is an oxazoline compound. 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 obtained by adding 58.9 parts of n-butanol, maintaining the reaction solution temperature at 80 ° C. for 2 hours, and then adding 0.86 part of 2-ethylhexyl acid phosphate.

(A6): Carbodilite (manufactured by Nisshinbo Chemical Co., Ltd.), which is a polycarbodiimide compound. Carbodiimide equivalent 340.
(B1): Acrylic resin aqueous dispersion polymerized with the following composition and having a glass transition point of 40 ° C. Ethyl acrylate / n-butyl acrylate / methyl methacrylate / N-methylol acrylamide / acrylic acid = 65/21/10/2 / 2 (% by weight) emulsion polymer (emulsifier: anionic surfactant)
(B2): 315 parts by weight of terephthalic acid, 299 parts by weight of isophthalic acid, 74 parts by weight of ethylene glycol, and 265 parts by weight of diethylene glycol as the component (B2a), (B2a) 953 parts by weight, isophorone diisocyanate Polyester polyurethane comprising 267 parts by weight, ethylene glycol 56 parts by weight, and dimethylolpropionic acid 67 parts by weight neutralized with ammonia and dispersed in water (concentration 23%, viscosity at 25 ° C., 30 mPa · s) )
(C1): 2-amino-2-methylpropanol hydrochloride (F1) which is a melamine crosslinking catalyst: silica particles having an average particle diameter of 0.07 μm.

Example 1:
(1) Preparation of polyester film Polyester (B) and (E) blended at a weight ratio of 80/20 as a surface layer, and polyester (A) only as a raw material for an intermediate layer, respectively, to two extruders 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 types / three layers (A / B / A). The film was coextruded to 2.5 / 45 / 2.5, and cooled and solidified while being in close contact with a mirror surface cooling drum having a surface temperature of 40 to 50 ° C. by using an electrostatic contact method to prepare 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 50 μm having a coating layer of 0.04 μm (after drying) was obtained.

(2) Adjustment of adhesive layer Acrylic copolymer having a weight average molecular weight of 600,000 (polystyrene equivalent) by copolymerizing butyl acrylate (100 parts by weight) and 6 parts by weight of acrylic acid in ethyl acetate by a conventional method. Solution (solid content 30% by weight) was obtained. To 100 parts by weight (solid content) of an acrylic copolymer, N, N-dimethylaminoethyl acrylate, 0.2 parts by weight, and 6 parts by weight of Tetrad C (manufactured by Mitsubishi Gas Chemical), which is an epoxy-based crosslinking agent, are added. An adhesive layer composition was obtained.

(3) Preparation of surface protective film The adhesive layer comprised from the said adhesion layer composition was apply | coated so that thickness (after drying) might be set to 25 micrometers on the film surface in which the application layer of the polyester film obtained above was not provided, 100 The surface protection film was obtained by drying at 5 ° C. for 5 minutes.

(4) Production of transparent conductive base film Optical polyester film O300E100 (Diafoil (registered trademark) manufactured by Mitsubishi Plastics, Inc., provided with a coating layer composed of the following coating layer composition example on one side) After applying an anchor layer composed of the following anchor layer composition on the film surface where the coating layer is not provided so that the coating amount (after drying) is 0.1 g / m ² , heat treatment is performed at 100 ° C. for 1 minute. A coated film provided with an anchor layer was obtained.
<Example of coating layer composition>
・ Oxazoline compounds: (I)
Polymer in which oxazoline group is branched to acrylic resin (Epocross WS-500 made by Nippon Shokubai)
・ Epoxy compound: (II) Polyglycerol polyglycidyl ether ・ Polyester resin: (IIIA)
Water dispersion of 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%)

・ Polyester resin: (IIIB)
Water dispersion of polyester resin copolymerized with the following composition: Monomer composition: (acid component) 2,6-naphthalenedicarboxylic acid / 5-sodium sulfoisophthalic acid // (diol component) ethylene glycol / diethylene glycol = 92/8 // 80/20 (mol%)
・ Particles: (IVA) Silica particles with an average particle size of 0.07 μm ・ Particles: (IVB) Zirconium oxide particles with an average particle size of 15 nm

  The above raw materials were blended at a ratio of I: II: IIIA: IIIB: IVA: IVB = 15: 15: 37: 15 :: 3: 15 to obtain a coating agent. The above coating agent was applied so that the coating layer had a dry thickness of 0.09 μm.

<Anchor layer composition>
Colcoat P (manufactured by Colcoat)
A 1% strength solution was prepared using isopropyl alcohol.
Furthermore, in the double-side coated film, the coating film was dried by heating a hard coat layer composition composed of the following hard coat layer composition on the coating layer at 60 ° C. for 1 minute. Thereafter, ultraviolet light with an integrated light quantity of 300 mJ / cm ² was irradiated with a high-pressure mercury lamp to obtain a double-side coated film with a hard coat layer having a coating amount (after drying) of 2 μm (after drying).

<Hard coat layer composition>
Binder (Nippon Paint “Luciferal NAB-007” 100 parts by weight Acrylic fine particles (Sekisui Plastics Co., Ltd. trade name “BMSA-18GN” (average particle size 0.8 μm) 0.1 part by weight) A hard coat layer composition having a solid content of 40% by weight was prepared by dispersing in ketone.

  In the obtained film with a hard coat layer, the transparent conductive base film was obtained by bonding together the adhesive layer of the surface protective film obtained above and the hard coat surface layer of the ITO base film.

  The thickness of the anchor layer by reactive sputtering using a sintered body material of 95% by weight of indium oxide and 5% by weight of tin oxide in an atmosphere of 0.4 Pa composed of 95% argon gas and 5% oxygen gas. A 25 nm thick ITO film (transparent conductive thin film) was formed. The obtained ITO film was crystallized by heat treatment at 180 ° C. for 90 minutes.

(6) Evaluation After crystallization, the surface protective film was peeled off, and the residual amount of the ester cyclic trimer on the hard coat surface was observed with an optical microscope (magnification 20 times). Confirmed.
When there is little or no oligomer remaining (precipitation): ◎
When there is little oligomer remaining (deposition): ○
Many oligomers remain (precipitated): ×
Excessive oligomer residue (precipitation): XX

  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 residual amount of the ester cyclic trimer on the hard coat surface of the obtained transparent conductive substrate film laminate was small and good. The properties of this film are shown in Table 3.

Examples 2 to 23:
In the manufacturing method of Example 1, it manufactured like Example 1 except changing a coating agent composition into the coating agent composition shown in Table 1 and Table 2, and obtained the transparent conductive base film laminated body.
The obtained polyester film and transparent conductive substrate film laminate had the characteristics shown in Table 3, the precipitation amount of the ester cyclic trimer was small, and the adhesion was good.

Example 24:
In the production method of Example 11, the transparent conductive group was prepared in the same manner as in Example 11 except that the thickness component ratio was changed to A / B / A = 1.5 / 20 / 1.5 and the thickness was changed to 23 μm. A material film laminate was obtained. Table 3 shows the characteristics of the obtained polyester film and transparent conductive substrate film laminate.

Example 25:
In the production method of Example 11, the transparent conductive base material was prepared in the same manner as in Example 11 except that the thickness component ratio was changed to A / B / A = 5.0 / 115 / 5.0 and the thickness was changed to 125 μm. A film laminate was obtained. Table 3 shows the characteristics of the obtained polyester film and transparent conductive substrate film laminate.

Example 26:
In the production method of Example 11, the transparent conductive base material was prepared in the same manner as in Example 11 except that the thickness component ratio was changed to A / B / A = 3.5 / 43 / 3.5 and the thickness was changed to 50 μm. A film laminate was obtained. Table 3 shows the characteristics of the obtained polyester film and transparent conductive substrate film laminate.

Example 27:
In Example 11, a polyester film and a transparent conductive substrate film laminate were obtained in the same manner as in Example 11 except that the coating solution was changed to coating on both sides of the film and the adhesive layer was provided on the coating layer. . 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. Furthermore, the adhesion between the coating layer and the adhesive layer is also good, and for the obtained transparent conductive substrate film laminate after crystallization, no residual ester cyclic trimer on the surface of the hard coat was observed. Good results.

Example 28:
(1 ') Polyesters (D) and (E) blended at a weight ratio of 80/20 as a surface layer and polyester (D) only as a raw material for an intermediate layer, and fed to two extruders, respectively. After being melted by heating at 285 ° C., 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 with two types and three layers (A / B / A). The film was coextruded so as to be /45/2.5, and cooled and solidified while being in close contact with a mirror-cooled drum having a surface temperature of 40 to 50 ° C. using an electrostatic contact method, to prepare 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. 7 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.
About (2)-(6), it manufactured like Example 1 and obtained the transparent conductive base film. Table 3 shows the characteristics of the obtained polyester film and transparent conductive substrate film laminate.

Comparative Example 1:
(1) Preparation of polyester film Polyester (A) and (E) blended at a weight ratio of 80/20 as a surface layer, and polyester (A) only as a raw material for an intermediate layer, respectively, to two extruders 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 types / three layers (A / B / A). The film was coextruded to 2.5 / 45 / 2.5, and cooled and solidified while being in close contact with a mirror surface cooling drum having a surface temperature of 40 to 50 ° C. by using an electrostatic contact method to prepare 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 50 μm having a coating layer of 0.04 μm (after drying) was obtained. It manufactured like (2)-(6) of Example 1, and obtained the transparent conductive base film.

  The film haze increase value (ΔH) by heat treatment of the obtained polyester film was large, and the amount of ester cyclic trimer precipitated was also large. Moreover, the residual amount of the ester cyclic trimer on the hard coat surface of the obtained transparent conductive substrate film laminate was large, and there was concern that the surrounding work environment and products would be contaminated. The properties of this film are shown in Table 3 below.

Comparative Examples 2-4:
In Comparative Example 1, it was produced in the same manner as in Comparative Example 1 except that the coating composition was changed to the coating composition shown in Tables 1 and 2, and a polyester film and a transparent conductive base film laminate were obtained. The film haze increase value (ΔH) by heat treatment of the obtained polyester film was large, and the amount of ester cyclic trimer precipitated was also large. Moreover, the residual amount of the ester cyclic trimer on the hard coat surface of the obtained transparent conductive substrate film laminate was also large. The properties of this film are shown in Table 3 below.

Comparative Examples 5-7:
In Example 1, it manufactured like Example 1 except changing a coating agent composition into the coating agent composition shown in Table 1 and Table 2, and obtained the polyester film and the transparent conductive base film laminate. The film haze increase value (ΔH) by heat treatment of the obtained polyester film was large, and the amount of ester cyclic trimer precipitated was also large. Moreover, about the residual amount of the ester cyclic trimer of the hard coat surface of the obtained transparent conductive base film laminated body, the result better than the effect of a base material and an adhesive was obtained. The properties of this film are shown in Table 3 below.

Comparative Example 8:
In Example 1, it manufactured like Example 1 except not providing an application layer, and obtained the polyester film and the transparent conductive base film laminate. As in Comparative Examples 5 to 7, the film haze increase value (ΔH) by heat treatment of the obtained polyester film was large, and the precipitation amount of the ester cyclic trimer was also large. Moreover, about the residual amount of the ester cyclic trimer of the hard coat surface of the obtained transparent conductive base film laminated body, the result better than the effect of a base material and an adhesive was obtained. The properties of this film are shown in Table 3 below.

Comparative Example 9:
In Example 11, the polyester film and the transparent conductive substrate film were prepared in the same manner as in Example 11 except that the thickness ratio was changed to A / B / A = 1/48/1 and the thickness was changed to 50 μm. A laminate was obtained. Table 3 shows the characteristics of the obtained polyester film and transparent conductive substrate film laminate.

Comparative Example 10:
In Example 11, the polyester film and transparent in the same manner as in Example 11 except that the thickness component ratio was changed to A / B / A = 1.5 / 47 / 1.5 and the thickness was changed to 50 μm. A conductive substrate film laminate was obtained. Table 3 shows the characteristics of the obtained polyester film and transparent conductive substrate film laminate.

  The film of the present invention is suitably used as a surface protective film for the manufacture and processing of precision electrical and electronic parts including a heat treatment step (for example, touch panels, electronic paper, electromagnetic shielding materials, liquid crystal panels, various sensors, solar cells, etc.). can do.

Claims (2)

A conductive polyester having a coating layer on at least one side of a laminated polyester film and having an ester cyclic trimer precipitation amount of 1.2 mg / m ² or less when heated at 150 ° C. for 90 minutes. Surface protective film for adhesive film. A transparent conductive substrate film laminate comprising the surface protective film for a conductive film according to claim 1 and a transparent conductive film substrate.