JP5753131B2 - Laminated polyester film - Google Patents

Description

  The present invention relates to a laminated polyester film. For example, after forming a surface functional layer such as a hard coat layer such as a transparent electrode such as a touch panel, it is suitable for applications where reduction of interference unevenness due to reflection of external light and slipperiness are required. The present invention relates to a laminated polyester film.

  In recent years, polyester films are often used for various optical films, transparent electrodes such as touch panels that are members of various displays, antireflection films, prism sheets, light diffusion sheets, electromagnetic wave shielding films, in-mold transfer films, It is used for applications such as in-mold label films. The base film used for these members is required to have excellent transparency and visibility.

  These films are often hard-coated in order to improve performance such as curling prevention, damage prevention, and surface hardness. In order to improve the adhesion between the polyester film used as a substrate and the hard coat layer, an easily adhesive coating layer is generally provided as an intermediate layer. For this reason, interference unevenness occurs unless the refractive index of the three layers of the polyester film, the easily adhesive coating layer, and the hard coat layer is taken into consideration.

  When a film with interference unevenness is used for a display such as a touch panel, the visibility becomes poor and it is difficult to use. Therefore, it is required to take measures against interference unevenness. In general, the refractive index of the coating layer for reducing interference unevenness is considered to be around the geometric mean of the refractive index of the polyester film of the substrate and the refractive index of the hard coat layer, and is adjusted to the refractive index around this. Ideally. Since the refractive index of the polyester film is high, it is generally necessary to design the coating layer with a high refractive index.

  In addition to the suppression of interference unevenness, there is an increasing need for a coating layer having a high refractive index in order to improve the visibility of the display. For example, in recent years, due to the increase in smartphones and the like, capacitive methods with patterned transparent electrodes are becoming mainstream among touch panels, and the refractive index difference of each layer of the display is reduced for the purpose of further improving the visibility of the display. Processing to make the patterning of the transparent electrode invisible is also required (Patent Documents 1 and 2).

  Moreover, in the above-mentioned use, the polyester film and surface functional layer with high transparency are calculated | required. Usually, particles are included in the polyester film for imparting slipperiness (Patent Document 3). In that case, the haze of the film becomes high and the film becomes whitish or under a fluorescent lamp. When observed, there is a drawback in that the graininess due to the particles is seen and the transparency becomes inferior. On the other hand, if the polyester film does not contain particles, the slipperiness is poor and the handling is not excellent. Therefore, there is a demand for a polyester film having high transparency and good slipperiness.

JP 2011-134464 A JP 2011-136562 A JP 2006-169467 A

  The present invention has been made in view of the above circumstances, and the problem to be solved is a laminated polyester that has less interference unevenness due to reflection of external light after forming a surface functional layer such as a hard coat layer and is excellent in slipperiness. To provide a film.

  As a result of intensive studies in view of the above circumstances, the present inventors have found that the use of a laminated polyester film having a specific configuration can easily solve the above-described problems, and have completed the present invention.

That is, the gist of the present invention is a laminated polyester film used for the purpose of making the patterning of the transparent electrode invisible, and is formed from a coating solution containing 20 to 40 % by weight of titanium oxide and a crosslinking agent as a ratio to the total nonvolatile components. Having a coated layer on one side of the polyester film, the minimum absolute reflectance of the coated layer is in the range of 5.7 to 6.3% at an arbitrary wavelength of 400 to 800 nm, It exists in the laminated polyester film characterized by having the coating layer formed from the coating liquid containing a type | mold agent on the other surface.

  According to the laminated polyester film of the present invention, when various surface functional layers such as a hard coat layer are laminated, there is little interference unevenness due to reflection of external light, excellent adhesion with various surface functional layers, and slipperiness. An excellent base film can be provided, and its industrial value is high.

  The polyester film constituting the laminated polyester film in the present invention may have a single layer structure or a multilayer structure, and may have four or more layers as long as it does not exceed the gist of the present invention other than a two-layer or three-layer structure. It may be a multilayer, and is not particularly limited. For example, in order to improve the slipperiness of the polyester film, a polyester film containing particles as described later on the surface layer, a polyester film containing no particles in the intermediate layer to ensure transparency, etc. It is preferable to use a three-layer structure in that the characteristics can be improved.

  The polyester used in the present invention may be a homopolyester or a copolyester. In the case of a homopolyester, those obtained by polycondensation of an aromatic dicarboxylic acid and an aliphatic glycol are preferred. Examples of the aromatic dicarboxylic acid include terephthalic acid and 2,6-naphthalenedicarboxylic acid, and examples of the aliphatic glycol include ethylene glycol, diethylene glycol, and 1,4-cyclohexanedimethanol. Typical polyester includes polyethylene terephthalate and the like. On the other hand, examples of the dicarboxylic acid component of the copolyester include isophthalic acid, phthalic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, adipic acid, sebacic acid, and oxycarboxylic acid (for example, p-oxybenzoic acid). 1 type or 2 types or more are mentioned, As a glycol component, 1 type or 2 types or more, such as ethylene glycol, diethylene glycol, propylene glycol, butanediol, 4-cyclohexane dimethanol, neopentyl glycol, is mentioned.

  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, titanium compounds and germanium compounds are preferable because they have high catalytic activity, can be polymerized in a small amount, and the amount of metal remaining in the film is small, so that the brightness of the film becomes high. Furthermore, since a germanium compound is expensive, it is more preferable to use a titanium compound.

  By the way, when the film is exposed to a high temperature such as a conductive layer forming step of a touch panel or a heat treatment step for molding, oligomers existing in the polyester film of the substrate, particularly ester cyclic trimers, are deposited on the film surface. There is a problem. Precipitation of ester cyclic trimer by heating due to defects such as when there is a large amount of precipitation of ester cyclic trimer, causing contamination in each step, and when it looks whitish and the transparency becomes poor There is a need for a film with a small amount.

In order to suppress the precipitation amount of the ester cyclic trimer after the heat treatment, it is preferable to produce a film from a polyester having a low ester cyclic trimer content. 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.

Furthermore, the polyester film is composed of three or more layers, and the outermost polyester layer of the polyester film is designed with a layer using a polyester raw material having a low ester cyclic trimer content. A method for suppressing the amount of precipitation is preferred.

  The content of the ester cyclic trimer contained in the polyester is about 1% by weight in a general production method. In the present invention, it is effective to use a polyester raw material in which the content of the ester cyclic trimer is preferably 0.7% by weight or less, more preferably 0.5% by weight or less by solid phase polymerization or the like. . The polyester raw material having an ester cyclic trimer content of 0.7% by weight or less contained in the outermost polyester layer of the polyester film is preferably 70% by weight or more of the total polyester raw material in the outermost polyester layer. More preferably, the amount of precipitation of the ester cyclic trimer after heating can be effectively suppressed when it is 80% by weight or more.

  Further, the thicker the outermost polyester layer of the polyester film, the more effectively the precipitation of the ester cyclic trimer from the inner polyester layer is effectively suppressed. The film thickness of the outermost polyester layer is preferably 4 μm or more, more preferably 5 μm or more. When the thickness is less than 4 μm, there is a concern that the effect is small, and it may be difficult to reduce the precipitation amount of the ester cyclic trimer by the method of reducing the content of the ester cyclic trimer of the polyester raw material.

  The polyester film of the present invention may contain an ultraviolet absorber in order to improve the weather resistance of the film and to prevent deterioration of the liquid crystal of a liquid crystal display used for a touch panel or the like. The ultraviolet absorber is not particularly limited as long as it is a compound that absorbs ultraviolet rays and can withstand the heat applied in the production process of the polyester film.

  As the ultraviolet absorber, there are an organic ultraviolet absorber and an inorganic ultraviolet absorber. From the viewpoint of transparency, an organic ultraviolet absorber is preferable. Although it does not specifically limit as an organic type ultraviolet absorber, For example, a cyclic imino ester type, a benzotriazole type, a benzophenone type etc. are mentioned. From the viewpoint of durability, a cyclic imino ester type and a benzotriazole type are more preferable. It is also possible to use two or more ultraviolet absorbers in combination.

  In the polyester layer of the film of the present invention, particles can be blended mainly for the purpose of imparting slidability and preventing scratches in each step, but from the viewpoint of transparency, particles are not blended. It is preferable that When the particles are blended, the kind of the particles to be blended is not particularly limited as long as it is a particle capable of imparting slipperiness, and specific examples thereof include, for example, silica, calcium carbonate, magnesium carbonate, barium carbonate, sulfuric acid. Examples thereof include inorganic particles such as calcium, calcium phosphate, magnesium phosphate, kaolin, aluminum oxide, and titanium oxide, and organic particles such as acrylic resin, styrene resin, urea resin, phenol resin, epoxy resin, and benzoguanamine resin. 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.

  Moreover, when mix | blending particle | grains, the average particle diameter of particle | grains is 3 micrometers or less normally, Preferably it is the range of 0.01-1.5 micrometers. When the average particle size exceeds 3 μm, the transparency of the film may be deteriorated, or the graininess due to the particles may be generated and the visibility may be deteriorated.

  The content of the particles depends on the average particle size, but in the polyester film layer containing the particles, it is usually in the range of 1000 ppm or less, preferably in the range of 500 ppm or less, more preferably in the range of 50 ppm or less (intentionally contained). Do not). When it exceeds 1000 ppm, transparency may deteriorate, or graininess due to particles may occur and visibility may deteriorate.

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 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, antistatic agents, thermal stabilizers, lubricants, dyes, pigments, and the like can be added to the polyester film in the present invention as necessary.

  Although the thickness of the polyester film in this invention will not be specifically limited if it can be formed into a film as a film, Usually, 10-300 micrometers, Preferably it is the range of 25-250 micrometers.

  Next, although the manufacture example of the polyester film in this invention is demonstrated concretely, it is not limited to the following manufacture examples at all. That is, a method of extruding pellets obtained by drying the polyester raw material described above from a die using a single screw extruder and cooling and solidifying the obtained molten sheet with a cooling roll to obtain an unstretched sheet is preferable. 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, and an electrostatic application adhesion method or a liquid application adhesion method is preferably employed. Next, the obtained unstretched sheet is stretched in the biaxial direction.

  In that case, first, the unstretched sheet is stretched in one direction by a roll or a tenter type stretching machine. The stretching temperature is usually 70 to 120 ° C., preferably 80 to 110 ° C., and the stretching ratio is usually 2.5 to 7 times, preferably 3.0 to 6 times. Next, the film is stretched in the direction perpendicular to the first stretching direction. In that case, the stretching temperature is usually 70 to 170 ° C., and the stretching ratio is usually 3.0 to 7 times, preferably 3.5 to 6 times. is there. Subsequently, heat treatment is performed at a temperature of 180 to 270 ° C. under tension or under relaxation within 30% to obtain a biaxially oriented film.

  In the above-described stretching, a method in which stretching in one direction is performed in two or more stages can be employed. In that case, it is preferable to carry out so that the draw ratios in the two directions finally fall within the above ranges.

  In the present invention, the simultaneous biaxial stretching method can be adopted for the production of the polyester film constituting the laminated polyester film. The simultaneous biaxial stretching method is a method in which the above-mentioned unstretched sheet is usually stretched and oriented in the machine direction and the width direction at a temperature controlled normally at 70 to 120 ° C., preferably 80 to 110 ° C. Is 4 to 50 times, preferably 7 to 35 times, and more preferably 10 to 25 times in terms of area magnification. Subsequently, heat treatment is performed at a temperature of 170 to 270 ° C. under tension or relaxation within 30% to obtain a stretched oriented film. With respect to the simultaneous biaxial stretching apparatus that employs the above-described stretching method, a conventionally known stretching method such as a screw method, a pantograph method, or a linear driving method can be employed.

  Next, formation of the coating layer which comprises the laminated polyester film in this invention is demonstrated. Regarding the coating layer, it may be provided by in-line coating which treats the film surface during the process of forming a polyester film, or offline coating which is applied outside the system on a once produced film may be adopted. Since the coating can be performed simultaneously with the film formation, the production can be handled at a low cost, and therefore in-line coating is preferably used.

  The in-line coating is not limited to the following, but for example, in the sequential biaxial stretching, the coating treatment can be performed particularly before the lateral stretching after the longitudinal stretching is finished. When the coating layer is provided on the polyester film by in-line coating, it is possible to apply at the same time as the film formation, and the coating layer can be processed at a high temperature in the heat treatment process of the polyester film after stretching. Performances such as adhesion to various surface functional layers that can be formed on the layer and heat-and-moisture resistance can be improved. Moreover, when coating before extending | stretching, the thickness of an application layer can also be changed with a draw ratio, and compared with offline coating, thin film coating can be performed more easily. That is, a film suitable as a polyester film can be produced by in-line coating, particularly coating before stretching.

  In the present invention, the polyester film has a coating layer formed from a coating solution containing a metal oxide and a crosslinking agent (hereinafter may be abbreviated as a first coating layer) on one surface, and a release agent. It is an essential requirement to have a coating layer (hereinafter sometimes abbreviated as “second coating layer”) formed from a coating solution containing a liquid on the other surface.

  The first coating layer of the film of the present invention has a refractive index designed in the vicinity of the base polyester film. In recent years, due to the increase in the number of smartphones and the like, capacitive touch panels with transparent electrodes patterned are becoming mainstream among touch panels, and in order to further improve the visibility of the screen, the interference unevenness is reduced and the transparent electrodes are not patterned. There is an increasing need for visualization processing, and in such processing, a surface functional layer such as a hard coat layer having a high refractive index is often provided on a polyester film as a base material. Especially when the refractive index of the surface functional layer is the same as that of the film of the base material, the refractive index of the coating layer is also designed to be equivalent to those, so that the interface reflection is achieved by optically eliminating the interface of each layer. The present inventors considered that the present invention can be effectively used for processing that makes the patterning of the transparent electrode invisible, while reducing interference unevenness.

  The metal oxide used for forming the first coating layer of the film of the present invention is mainly used for adjusting the refractive index of the coating layer. In particular, a metal oxide having a high refractive index is preferably used, and a refractive index of 1.7 or more is preferably used. Specific examples of the metal oxide include, for example, zirconium oxide, titanium oxide, tin oxide, yttrium oxide, antimony oxide, indium oxide, zinc oxide, antimontin oxide, indium tin oxide, and the like. You may use 2 or more types. Among these, zirconium oxide and titanium oxide are more preferably used because they are excellent in transparency when used for forming a coating layer, and titanium oxide is most suitable because it has a particularly high refractive index.

  The metal oxide is preferably used in the form of particles because there is a concern that the adhesion may be lowered depending on the use form, and the average particle size is preferably 100 nm or less, more preferably from the viewpoint of transparency. It is 50 nm or less, more preferably 25 nm or less.

  The crosslinking agent used for formation of the 1st application layer of the film of this invention is used for the improvement of the intensity | strength of an application layer, and the adhesiveness with various surface functional layers. Various known crosslinking agents can be used as the crosslinking agent, and examples thereof include oxazoline compounds, epoxy compounds, isocyanate compounds, carbodiimide compounds, melamine compounds, and silane coupling compounds. Of these, oxazoline compounds, epoxy compounds, isocyanate compounds, and carbodiimide compounds are preferably used from the viewpoint of improving adhesion, and melamine from the viewpoint of improving the strength of the coating layer such as solvent resistance. A compound is preferably used.

  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 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 dimethyl malonate, diethyl malonate, methyl acetoacetate, ethyl acetoacetate and acetylacetone, mercaptan compounds such as butyl mercaptan and dodecyl mercaptan, lactam compounds such as ε-caprolactam and δ-valerolactam , Amine compounds such as diphenylaniline, aniline, ethyleneimine, acetanilide, acid amide compounds of acetic acid amide, formaldehyde, acetoald Examples include oxime compounds such as 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.

  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.

  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.

  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.

  In addition, the first coating layer of the film of the present invention is formed by improving the coating appearance, reducing interference unevenness when various surface functional layers such as a hard coat layer are laminated on the coating layer, transparency and adhesion. It is also possible to use a polymer for improving the properties.

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

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

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

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

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

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

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

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

  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, quaternary ammonium salt, and the like, and a carboxyl group is preferable. As a method for introducing a carboxyl group into a urethane resin, various methods can be taken in each stage of the polymerization reaction. For example, there are a method of using a carboxyl group-containing resin as a copolymer component during prepolymer synthesis, and a method of using a component having a carboxyl group as one component such as polyol, polyisocyanate, and chain extender. In particular, a method in which a desired amount of carboxyl groups is introduced using a carboxyl group-containing diol depending on the amount of this component charged is preferred.

For example, dimethylolpropionic acid, dimethylolbutanoic acid, bis- (2-hydroxyethyl) propionic acid, bis- (2-hydroxyethyl) butanoic acid and the like are copolymerized with a diol used for polymerization of a urethane resin. Can do. The carboxyl group is preferably in the form of a salt neutralized with ammonia, amine, alkali metal, inorganic alkali or the like. Particularly preferred are ammonia, trimethylamine and triethylamine.
In such a polyurethane resin, a carboxyl group from which the neutralizing agent has been removed in the 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, polyester resins are particularly preferable from the viewpoint that a large number of aromatic compounds such as benzene rings can be contained in the molecule, thereby increasing the refractive index.

  In addition, in order to make it easier to adjust the refractive index of the coating layer, for example, condensation of naphthalene, anthracene, phenanthrene, naphthacene, benzo [a] anthracene, benzo [a] phenanthrene, pyrene, benzo [c] phenanthrene, perylene, etc. It is preferable to use a compound having a polycyclic aromatic structure in combination.

  In consideration of applicability on the polyester film, the compound having a condensed polycyclic aromatic is preferably a polymer compound such as a polyester resin, an acrylic resin, or a urethane resin. In particular, polyester resins are more preferable because more condensed polycyclic aromatics can be introduced.

  As a method of incorporating the condensed polycyclic aromatic into the polyester resin, for example, two or more hydroxyl groups are introduced into the condensed polycyclic aromatic as a substituent to form a diol component or a polyvalent hydroxyl component, or There is a method in which two or more acid groups are introduced to prepare a dicarboxylic acid component or a polyvalent carboxylic acid component.

  In the laminated polyester film production process, the condensed polycyclic aromatic contained in the coating layer is preferably a compound having a naphthalene structure in that it is difficult to be colored. In addition, a resin incorporating a naphthalene structure as a polyester constituent is suitably used in terms of good adhesion to various surface functional layers formed on the coating layer and transparency. Representative examples of the naphthalene structure include 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, and 2,7-naphthalenedicarboxylic acid.

  In addition to the hydroxyl group and the carboxylic acid group, the condensed polycyclic aromatic has a refractive index of a refractive index by introducing a substituent containing a sulfur element, an aromatic substituent such as a phenyl group, a halogen element group, and the like. Improvements can be expected, and substituents such as alkyl groups, ester groups, amide groups, sulfonic acid groups, carboxylic acid groups, and hydroxyl groups may be introduced from the viewpoint of coating properties and adhesion.

  In the film of the present invention, particles other than the metal oxides described above may be used in combination with the formation of the coating layer for the purpose of blocking the coating layer and improving slipperiness. The average particle size is preferably in the range of 1.0 μm or less, more preferably 0.5 μm or less, particularly preferably 0.2 μm or less from the viewpoint of the transparency of the film. Moreover, since it depends on the film thickness of the coating layer, it is not general, but from the viewpoint of further improving the slipperiness, it is preferably in the range of 0.02 μm or more, more preferably 0.05 μm or more. Specific examples of the particles include silica, alumina, kaolin, calcium carbonate, and organic particles.

  The second coating layer of the film of the present invention is provided to improve the slipperiness of the film and facilitate the handling of the film in the production process of the polyester film and the post-processing process.

  The mold release agent used for forming the second coating layer of the film of the present invention is used for improving the slipperiness of the film, and is not particularly limited, and conventionally known mold release agents can be used. Yes, for example, wax, fluorine compound, long chain alkyl compound, silicone compound and the like. These release agents may be used alone or in combination.

  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 fluorine compound is a compound containing a fluorine atom in the compound. Organic fluorine compounds are preferably used in terms of planarity due to 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. . In view of heat resistance and contamination, a polymer compound is preferable, and a perfluoroalkyl group-containing compound is preferable in order to effectively improve slipperiness.

  The long-chain alkyl compound is a compound having a linear or branched alkyl group having 6 or more, particularly preferably 8 or more carbon atoms. Specific examples include, but are not limited to, long-chain alkyl group-containing polyvinyl resins, long-chain alkyl group-containing acrylic resins, long-chain alkyl group-containing polyester resins, long-chain alkyl group-containing amine compounds, long-chain alkyl groups. And an ether compound, a long-chain alkyl group-containing quaternary ammonium salt, and the like. In view of heat resistance and contamination, a polymer compound is 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.

  These release agents may be used alone or in combination. Further, among these release agents, a wax is more preferably used because good slipperiness can be imparted with a small amount.

  In the formation of the second coating layer of the film of the present invention, it is possible to use a polymer and a crosslinking agent used in the formation of the first coating layer in order to improve the coating appearance, transparency, and control of slipperiness. It is. In particular, it is preferable to use a melamine compound in combination in order to strengthen the coating layer and bring out stable slipperiness.

  Moreover, in the range which does not impair the main point of this invention, it is also possible to use a particle together with the formation of the 2nd coating layer of the film of this invention for the purpose of the blocking property of a coating layer, slipperiness improvement, etc. However, when using particles having a large average particle diameter, the transparency of the film may be deteriorated. Therefore, when using particles, particles having a small average particle diameter are preferable, and 0.3 μm or less, more preferably 0.1 μm or less. It is.

  Furthermore, in the range that does not impair the gist of the present invention, the formation of the first coating layer and the second coating layer, if necessary, defoaming agent, coating property improver, thickener, organic lubricant, antistatic agent, Ultraviolet absorbers, antioxidants, foaming agents, dyes, pigments and the like may be used.

  As a ratio with respect to all the non-volatile components in the coating liquid which forms the 1st coating layer which comprises the laminated polyester film in this invention, a metal oxide is the range of 5 to 50 weight% normally, More preferably, it is 10 to 45 weight%. The range is more preferably 20 to 40% by weight. If it is out of these ranges, due to interference unevenness after the formation of the surface functional layer such as the hard coat layer, if the visibility is not good, the coating appearance deteriorates, the adhesion with the surface functional layer such as the hard coat layer is There may be concerns about the potential for decline.

  As a ratio with respect to all the non-volatile components in the coating liquid which forms the 1st coating layer which comprises the laminated polyester film in this invention, the total amount of a crosslinking agent is the range of 1-50 weight% normally, More preferably, it is 5-40 weight. %, More preferably in the range of 10 to 30% by weight. If it is out of these ranges, there is a concern that the adhesion with the surface functional layer such as the hard coat layer may be lowered, if the coating appearance deteriorates, interference after the formation of the surface functional layer such as the hard coat layer The visibility may not be good due to unevenness.

  In the compound having a condensed polycyclic aromatic that can be used in the first coating layer constituting the laminated polyester film in the present invention, the proportion of the condensed polycyclic aromatic in the compound is preferably 5 to 80% by weight. More preferably, it is the range of 10 to 60% by weight. Moreover, as a ratio with respect to all the non-volatile components in the coating liquid which forms a 1st coating layer, content of the compound which has condensed polycyclic aromatic is normally 90 weight% or less, Preferably it is 10-80 weight%. The range is more preferably 20 to 70% by weight. By using within these ranges, the refractive index of the coating layer can be easily adjusted, and interference unevenness after forming a surface functional layer such as a hard coat layer can be easily reduced. The ratio of the condensed polycyclic aromatic can be determined by, for example, dissolving and extracting the coating layer with an appropriate solvent or warm water, separating by chromatography, analyzing the structure by NMR or IR, and further pyrolyzing GC-MS (gas It can be determined by analyzing by chromatography mass spectrometry) or optical analysis.

  As a ratio with respect to all the non-volatile components in the coating liquid forming the second coating layer constituting the laminated polyester film in the present invention, the release agent is usually in the range of 1% by weight or more, preferably in the range of 3 to 90% by weight, More preferably, it is 5 to 85% by weight. If it is less than 1% by weight, the slipperiness may not be sufficient.

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

  When providing a coating layer by in-line coating, the above-mentioned series of compounds is applied as an aqueous solution or dispersion, and the coating solution adjusted to a solid content concentration of about 0.1 to 50% by weight as a guide is applied onto the polyester film. It is preferable to produce a laminated polyester film. Moreover, in the range which does not impair the main point of this invention, a small amount of organic solvents may be contained in the coating liquid for the purpose of improving dispersibility in water, improving film-forming properties, and the like. Only one type of organic solvent may be used, or two or more types may be used as appropriate.

  Regarding the laminated polyester film in the present invention, the thickness of the coating layer provided on the polyester film is usually in the range of 0.001 to 1 μm, preferably 0.01 to 0.5 μm, more preferably 0.02 to 0.2 μm. It is. When the film thickness is out of the above range, the blocking of the coating layer may deteriorate or the coating appearance may deteriorate.

  In the film of the present invention, the coating layer can be formed by a conventionally known coating method such as reverse gravure coating, direct gravure coating, roll coating, die coating, bar coating, curtain coating, spray coating, or the like.

  In the present invention, the drying and curing conditions for forming the coating layer on the polyester film are not particularly limited. For example, when the coating layer is provided by off-line coating, it is usually 3 to 40 at 80 to 200 ° C. The heat treatment may be performed for 2 seconds, preferably 100 to 180 ° C. for 3 to 40 seconds.

  On the other hand, when the coating layer is provided by in-line coating, heat treatment is usually performed at 70 to 270 ° C. for 3 to 200 seconds as a guide.

  Further, irrespective of off-line coating or in-line coating, heat treatment and active energy ray irradiation such as ultraviolet irradiation may be used in combination as required. The polyester film constituting the laminated polyester film in the present invention may be subjected to surface treatment such as corona treatment or plasma treatment in advance.

  The first coating layer in the present invention has a refractive index adjusted to the same level as that of the base polyester film in order to suppress interference unevenness and the like to a higher degree. For example, in the case of a general biaxially stretched polyethylene terephthalate film including the present invention, the refractive index is about 1.65. In that case, the refractive index of the first coating layer is preferably 1.63-1. .67, more preferably 1.64 to 1.66, and most preferably 1.65.

  Within the scope of the present invention, there is a relationship between the refractive index of the coating layer and the absolute reflectance of the coating layer, and when the refractive index is high, the reflectance is high. That is, the absolute reflectance of the first coating layer in the present invention is usually in the range of 5.5 to 6.5%, preferably 5.6 to 6.4%, at an arbitrary wavelength whose minimum value is 400 to 800 nm. More preferably, it is 5.7 to 6.3%. When the reflectance is out of this range, interference unevenness becomes strong when a surface functional layer such as a hard coat having a high refractive index in the vicinity of the polyester film of the base material is provided on the coating layer, and visibility is reduced. There is a case.

  The polyester film of the present invention is generally provided with a surface functional layer such as a hard coat layer on the first coating layer. Although it does not specifically limit as a material used for a hard-coat layer, For example, hardened | cured materials, such as reactive silicon compounds, such as monofunctional (meth) acrylate, polyfunctional (meth) acrylate, and tetraethoxysilane, are mentioned. Among these, from the viewpoint of achieving both productivity and hardness, a polymerization cured product of a composition containing an active energy ray-curable (meth) acrylate is particularly preferable.

  The composition containing the active energy ray-curable (meth) acrylate is not particularly limited. For example, a mixture of one or more known active energy ray-curable monofunctional (meth) acrylates, bifunctional (meth) acrylates, polyfunctional (meth) acrylates, and commercially available as an active energy ray-curable hard coat resin material In addition, those other than these may be used as long as the object of the present embodiment is not impaired.

  The active energy ray-curable monofunctional (meth) acrylate is not particularly limited. For example, methyl (meth) acrylate, n-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) ) Acrylate, stearyl (meth) acrylate, cyclohexyl (meth) acrylate, alkyl (meth) acrylate such as isobornyl (meth) acrylate, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, etc. Alkyl (meth) acrylate, methoxyethyl (meth) acrylate, ethoxyethyl (meth) acrylate, methoxypropyl (meth) acrylate, ethoxypropyl (meth) acrylate, etc. Amino group-containing (meth) acrylates such as xylalkyl (meth) acrylate, benzyl (meth) acrylate, aromatic (meth) acrylate such as phenoxyethyl (meth) acrylate, diaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, Methoxyethylene glycol (meth) acrylate, phenoxy polyethylene glycol (meth) acrylate, ethylene oxide modified (meth) acrylate such as phenylphenol ethylene oxide modified (meth) acrylate, glycidyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, Examples include (meth) acrylic acid.

  The active energy ray-curable difunctional (meth) acrylate is not particularly limited, and for example, 1,4-butanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, 1,6- Hexanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, alkanediol di (meth) acrylate such as tricyclodecane dimethylol di (meth) acrylate, bisphenol A ethylene oxide modified di (meth) acrylate Bisphenol F ethylene oxide modified di (meth) acrylate and other bisphenol modified di (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, urethane di (meth) acrylate And epoxy di (meth) acrylate.

  The active energy ray-curable polyfunctional (meth) acrylate is not particularly limited, and examples thereof include dipentaerythritol hexa (meth) acrylate, pentaerythritol tetra (meth) acrylate, and ditrimethylolpropane tetra (meth) acrylate. , Pentaerythritol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, isocyanuric acid ethylene oxide modified tri (meth) acrylate, ε-caprolactone modified tris (acryloxyethyl) isocyanurate Acrylate, pentaerythritol triacrylate hexamethylene diisocyanate urethane prepolymer, pentaerythritol triacrylate toluene diisocyanate urea Down prepolymers, urethane acrylates such as dipentaerythritol pentaacrylate hexamethylene diisocyanate urethane prepolymer, and the like.

  Other components contained in the composition containing the active energy ray-curable (meth) acrylate are not particularly limited. Examples thereof include inorganic or organic fine particles, polymerization initiators, polymerization inhibitors, antioxidants, antistatic agents, dispersants, surfactants, light stabilizers, and leveling agents. In addition, when the film is dried after film formation in the wet coating method, an arbitrary amount of solvent can be added.

  As a method for forming the hard coat layer, when an organic material is used, a general wet coat method such as a roll coat method or a die coat method is employed. The formed hard coat layer can be subjected to a curing reaction by heating, irradiation with active energy rays such as ultraviolet rays and electron beams as necessary.

  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 measurement method and evaluation method used in the present invention are as follows.

(1) Measuring method of intrinsic viscosity of polyester 1 g of polyester from which other polymer components and pigments incompatible with polyester have been removed are weighed accurately, and 100 ml of a mixed solvent of phenol / tetrachloroethane = 50/50 (weight ratio) is added. And dissolved at 30 ° C.

(2) Measuring method of amount of 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 chloroform / hexafluoro-2-isopropanol ratio 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 further washed with a mixed solvent having a chloroform / methanol ratio of 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 subjected to liquid chromatography (manufactured by Shimadzu Corporation: LC-7A, mobile phase A: acetonitrile, mobile phase B: 2% acetic acid aqueous solution, column: Mitsubishi Chemical ( Co., Ltd. “MCI GEL ODS 1HU”, column temperature: 40 ° C., flow rate: 1 ml / min, detection wavelength: 254 nm), and the amount of ester cyclic trimer in DMF was determined. Dividing by the amount of the polyester raw material dissolved in the fluoro-2-isopropanol mixed solvent, the amount of the ester cyclic trimer contained (% by weight) was obtained. 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 accurately measured DMF.

(3) Measuring method of average particle diameter The coating layer was observed using TEM (H-7650 manufactured by Hitachi High-Technologies Corporation, acceleration voltage 100V), and the average value of the particle diameters of 10 particles was defined as the average particle diameter. .

(4) Method for measuring film thickness of coating layer The surface of the coating layer was dyed with RuO ₄ and embedded in an epoxy resin. Thereafter, the section prepared by ultramicrotomy stained with RuO _4, a coating layer cross-section was measured by using a TEM (Hitachi High Technologies Corporation H-7650, accelerating voltage 100 V).

(5) Evaluation method of absolute reflectance from the first coating layer surface in the polyester film In advance, a black tape (vinyl tape VT-50 manufactured by Nichiban Co., Ltd.) is pasted on the measurement back surface of the polyester film, and a spectrophotometer (JASCO Corporation) Using UV-Vis spectrophotometer V-570 and automatic absolute reflectance measuring device ARM-500N), synchronous mode, incident angle 5 °, N-polarized light, response Fast, data collection interval 1.0 nm, bandwidth 10 nm The absolute reflectance in the wavelength range of 400 to 800 nm was measured on the coating layer surface at a scanning speed of 1000 m / min, and the reflectance at the minimum value was evaluated.

(6) Interference unevenness evaluation method On the first coating layer side of the polyester film, 60 parts by weight of dipentaerythritol hexaacrylate, 15 parts by weight of 2-hydroxy-3-phenoxypropyl acrylate, 25 parts by weight of antimony pentoxide, photopolymerization start Apply a mixed coating solution of 1 part by weight of agent (trade name: Irgacure 184, manufactured by Ciba Specialty Chemicals Co., Ltd.) and 200 parts by weight of methyl ethyl ketone so that the dry film thickness is 5 μm, and cure by irradiating with ultraviolet rays to hard coat layer Formed. Observe the interference unevenness on the first coating layer side visually under the three-wavelength type fluorescent lamp of the obtained film, ◎ if the interference unevenness is not confirmed, ○ if the thin sparse interference unevenness is confirmed ○ The thin ones where linear interference unevenness can be confirmed are indicated by Δ, and the ones where clear interference unevenness is confirmed are indicated by ×.

(7) Method for evaluating adhesion of first coating layer A hard coat layer was formed in the same manner as in the evaluation in (6) above. The obtained film was subjected to 10 × 10 cross-cut after 50 hours in an environment of 60 ° C. and 90% RH, and a tape of 18 mm width (cello tape (registered trademark) CT manufactured by Nichiban Co., Ltd.) was formed thereon. -18) is attached and the peeled surface is observed after abrupt peeling at a 180 ° peel angle. If the peeled area is less than 5%, ◎ if it is 5% or more but less than 10%, ○, 10% or more and 50%. If it was less than △, it was marked as x if it was 50% or more.

(8) Evaluation method of slipperiness When the film is overlapped so that the first coating layer and the second coating layer face each other and slid with a finger, the case where it slides easily is not good, and the slipping property is not sufficient and there is a catch. △, and when not slipping, ×.

(9) Transparency evaluation method When the film is visually observed under a three-wavelength light region type fluorescent lamp, the particle feeling (the dots resulting from the particles in the film) is not observed, and there is a clear feeling. The case where there was a particle feeling or the case where whitishness was observed was taken as x.

The polyester used in the examples and comparative examples was prepared as follows.
<Method for producing polyester (A)>
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 produced 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 performed for 80 minutes to obtain the intrinsic viscosity. 0.63 polyester (A) was obtained.

<Method for producing polyester (B)>
100 parts by weight of dimethyl terephthalate, 60 parts by weight of ethylene glycol, and magnesium acetate tetrahydrate as a catalyst were subjected to an esterification reaction at 225 ° C. in a nitrogen atmosphere at 900 ppm with respect to the produced polyester. Subsequently, 3500 ppm of orthophosphoric acid was added to the produced polyester, and 70 ppm of germanium dioxide was added to the produced polyester. The temperature was raised to 280 ° C. over 2 hours and 30 minutes, and the pressure was reduced to an absolute pressure of 0.4 kPa. After 85 minutes of melt polycondensation, polyester (B) having an intrinsic viscosity of 0.64 was obtained.

<Method for producing polyester (C)>
100 parts by weight of dimethyl terephthalate, 60 parts by weight of ethylene glycol, 0.09 parts by weight of magnesium acetate tetrahydrate as a catalyst are taken in the reactor, the reaction start temperature is 150 ° C., and the reaction temperature is gradually increased as methanol is distilled off. The temperature was 230 ° C. after 3 hours. After 4 hours, the transesterification reaction was substantially terminated. After adding 0.04 part by weight of ethyl acid phosphate to this reaction mixture, 0.04 part by weight of antimony trioxide was added and a polycondensation reaction was carried out for 4 hours. The temperature was gradually raised from 230 ° C. and 280 ° C. It was. On the other hand, the pressure is gradually reduced from normal pressure, and finally 0.3 mmHg. After the start of the reaction, due to the change in stirring power of the reaction vessel, the intrinsic viscosity is 0.65, ester cyclic trimer (ethylene terephthalate cyclic trimer) A polyester (C) having a content of (body) of 0.97% 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 220 ° C., with an intrinsic viscosity of 0.75 and an ester cyclic trimer content of 0.46% by weight. Polyester (D) was obtained.

<Method for producing polyester (E)>
In the production method of polyester (A), polyester (E) is produced using the same method as the production method of polyester (A) except that 0.5 part by weight of silica particles having an average particle diameter of 0.1 μm is added before melt polymerization. Got.

<Method for producing polyester (F)>
In the production method of the polyester (A), the polyester (F) is produced using the same method as the production method of the polyester (A) except that 0.5 part by weight of silica particles having an average particle diameter of 3.2 μm is added before the melt polymerization. Got.

Examples of compounds constituting the coating layer are as follows.
(Example compounds)
Metal oxide: (I) Titanium oxide particles with an average particle size of 15 nm

・ Oxazoline compounds: (IIA)
Acrylic polymer having an oxazoline group and a polyalkylene oxide chain Epocros WS-500 (manufactured by Nippon Shokubai Co., Ltd., containing about 38% by weight of 1-methoxy-2-propanol solvent)
Epoxy compound: (IIB) Polyglycerol polyglycidyl ether.
・ Isocyanate compounds: (IIC)
158 parts by weight of hexamethylene diisocyanate trimer, 26 parts by weight of methoxypolyethylene glycol (OH value = 81 mg KOH / g), 27.8 parts by weight of diethyl diethylene glycol and 0.001 part by weight of dioctyltin laurate were reacted at 85 ° C. Thereafter, the mixture was allowed to cool, and 66 parts by weight of methyl ethyl ketone oxime was added dropwise to react. Subsequently, 115 parts by weight of 1,6-hexamethylenediol-based polycarbonate diol (OH value = 56 mgKOH / g), 1.2 parts by weight of trimethylolpropane (OH value = 1254 mgKOH / g), dimethylolpropionic acid (OH value = 837 mgKOH) / G) 7.6 parts by weight and 50 parts by weight of dimethyldipropylene glycol were added, and after stirring, 40.3 parts by weight of isophorone diisocyanate was added and reacted. After allowing to cool, 8.2 parts by weight of hexamethylene diisocyanate trimer was added, and after stirring, 5.8 parts by weight of triethylamine was added and stirred. A block isocyanate compound obtained by dropping 450 parts by weight of water into this mixed solution and dropping and stirring 21 parts by weight of a 15% aqueous diethylenetriamine solution.
・ Melamine compound: (IID) Hexamethoxymethylmelamine

・ Condensed polycyclic aromatic polyester resin: (IIIA)
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%)
・ Polyester resin (IIIB)
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%)
・ Urethane resin (IIIC)
Hydran AP-40 (manufactured by DIC Corporation), which is a carboxylic acid water-dispersed polyester polyurethane resin
・ Acrylic resin: (IIID)
Aqueous dispersion of acrylic resin polymerized with the following composition: Emulsion polymer of ethyl acrylate / n-butyl acrylate / methyl methacrylate / N-methylol acrylamide / acrylic acid = 65/21/10/2/2 (% by weight) (emulsifier: Anionic surfactant)

・ Releasing agent: (IVA)
An emulsification facility with an internal volume of 1.5 L equipped with a stirrer, thermometer, temperature controller, melting point 105 ° C., acid value 16 mgKOH / g, density 0.93 g / mL, average molecular weight 5000 oxidized polyethylene wax 300 g, ion-exchanged water 650 g 50 g of decaglycerin monooleate surfactant and 10 g of 48% potassium hydroxide aqueous solution were added and replaced with nitrogen, then sealed, stirred at 150 ° C for 1 hour at high speed, cooled to 130 ° C, and passed through a high-pressure homogenizer at 400 atm. A wax emulsion cooled to 40 ° C.
・ Releasing agent (fluorine compound): (IVB)
In a glass reaction vessel, perfluoroalkyl group-containing acrylate CF ₃ (CF ₂ ) _n CH ₂ CH ₂ OCOCH═CH ₂ (n = 5 to 11, n average = 9) 80.0 g, acetoacetoxyethyl 20.0 g of methacrylate, 0.8 g of dodecyl mercaptan, 354.7 g of deoxygenated pure water, 40.0 g of acetone, 1.0 g of C ₁₆ H ₃₃ N (CH ₃ ) ₃ Cl and C ₈ H ₁₇ C ₆ H ₄ O (CH ₂ CH ₂ O) nH (n = 8) (3.0 g) was added, 0.5 g of azobisisobutylamidine dihydrochloride was added, and a copolymerization reaction was carried out at 60 ° C. for 10 hours with stirring under a nitrogen atmosphere. A coalescence emulsion was obtained.

・ Release agent (long chain alkyl compound): (IVC)
To a four-necked flask, 200 parts of xylene and 600 parts of octadecyl isocyanate were added 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, and 140 parts of xylene was added and heated to dissolve completely. After repeating the operation of adding methanol again to precipitate several times, the precipitate was washed with methanol and dried and ground.

-Particles: (V) Silica particles with an average particle size of 0.07 μm

Example 1:
Polyester (D) is used as a raw material for the outermost layer (surface layer), and mixed raw materials obtained by mixing polyester (A) and (B) at a ratio of 97% and 3%, respectively, are used as raw materials for the intermediate layer. Are melted at 285 ° C. and then coextruded and cooled on a cooling roll set at 40 ° C. in a layer configuration of two types and three layers (surface layer / intermediate layer / surface layer = 1: 6: 1 discharge amount). Solidified to obtain an unstretched sheet. Next, the film was stretched 3.4 times in the longitudinal direction at a film temperature of 85 ° C. using the difference in peripheral speed of the roll, and then an aqueous coating solution A1 shown in Table 1 below was applied to one side of the longitudinally stretched film (first (Formation of coating layer) On the opposite side, an aqueous coating solution B1 shown in Table 2 below was coated (formation of the second coating layer), led to a tenter, stretched 4.0 times at 120 ° C in the transverse direction, and 225 ° C 50% thick polyester film having a first coating layer having a coating layer thickness (after drying) of 0.10 μm and a second coating layer having a thickness of 0.05 μm. Got.

  When the absolute reflectance of the first coating layer of the obtained polyester film was measured, the minimum value was 5.6%, the film after forming the hard coat layer had no strong interference unevenness and good adhesion. there were. Moreover, the slipperiness and transparency of the film were also good. The properties of this film are shown in Table 3 below.

Examples 2-35:
In Example 1, it manufactured like Example 1 except having changed an application agent composition into an application agent composition shown in Table 1 or Table 2, and obtained a polyester film. As shown in Table 3 or Table 4, the finished polyester film had good adhesion, interference unevenness level, slipperiness and transparency of the coating layer.

Example 36:
A mixed raw material in which polyesters (D) and (E) are mixed at a ratio of 99% and 1%, respectively, is used as a raw material for the outermost layer (surface layer), and polyesters (A) and (B) are respectively 97% and 3%. Each of the mixed raw materials is fed to two extruders as a raw material for the intermediate layer, melted at 285 ° C., and then two types and three layers (surface layer / intermediate layer / A non-stretched sheet was obtained by coextrusion and cooling and solidification in a layer configuration of (surface layer = 1: 6: 1 discharge amount). Next, the film was stretched 3.4 times in the longitudinal direction at a film temperature of 85 ° C. using the roll peripheral speed difference, and then an aqueous coating liquid A3 shown in Table 1 below was applied to one side of the longitudinally stretched film (first (Formation of coating layer) On the opposite side, an aqueous coating solution B1 shown in Table 2 below was coated (formation of the second coating layer), led to a tenter, stretched 4.0 times at 120 ° C in the transverse direction, and 225 ° C 50% thick polyester film having a first coating layer having a coating layer thickness (after drying) of 0.03 μm and a second coating layer having a thickness of 0.05 μm. Got. When the obtained polyester film was evaluated, the adhesion, interference unevenness level, slipperiness and transparency of the coating layer were good. The properties of this film are shown in Table 4 below.

Comparative Examples 1-3:
In Example 1, it manufactured like Example 1 except having changed an application agent composition into an application agent composition shown in Table 1 or Table 2, and obtained a polyester film. When the finished laminated polyester film was evaluated, as shown in Table 5 below, there was a case where clear interference unevenness could be observed when the adhesion was poor.

Comparative Example 4:
In Example 1, it manufactured similarly to Example 1 except not providing a 1st coating layer, and obtained the polyester film. When the completed laminated polyester film was evaluated, as shown in Table 5 below, the adhesion was poor.

Comparative Example 5:
In Example 1, it manufactured like Example 1 except having changed an application agent composition into an application agent composition shown in Table 1 or Table 2, and obtained a polyester film. When the completed laminated polyester film was evaluated, as shown in Table 5 below, the slipperiness was poor.

Comparative Example 6:
In Comparative Example 5, a polyester film was obtained in the same manner as in Comparative Example 5 except that the second coating layer was not provided. When the completed laminated polyester film was evaluated, as shown in Table 5 below, the slipperiness was poor.

Comparative Example 7:
A mixed raw material in which polyesters (D) and (F) are mixed at a ratio of 95% and 5%, respectively, is used as a raw material for the outermost layer (surface layer), and polyesters (A) and (B) are respectively 97% and 3%. Each of the mixed raw materials is fed to two extruders as a raw material for the intermediate layer, melted at 285 ° C., and then two types and three layers (surface layer / intermediate layer / A non-stretched sheet was obtained by coextrusion and cooling and solidification in a layer configuration of (surface layer = 1: 6: 1 discharge amount). Next, the film was stretched 3.4 times in the longitudinal direction at a film temperature of 85 ° C. using the roll peripheral speed difference, and then an aqueous coating liquid A3 shown in Table 1 below was applied to one side of the longitudinally stretched film (first Formation of coating layer), led to a tenter, stretched 4.0 times at 120 ° C in the lateral direction, heat-treated at 225 ° C, relaxed by 2% in the lateral direction, and the coating layer thickness (after drying) A 50 μm-thick polyester film having a 0.03 μm first coating layer was obtained. When the obtained polyester film was evaluated, it was inferior in transparency. The properties of this film are shown in Table 5 below.

  The film of the present invention can be suitably used for applications where reduction of interference unevenness due to external light reflection and slipperiness are required after forming a surface functional layer such as a hard coat layer such as a transparent electrode such as a touch panel. .

Claims (3)

A laminated polyester film used for the purpose of invisible patterning of a transparent electrode, and a coating layer formed from a coating solution containing 20 to 40 % by weight of titanium oxide and a crosslinking agent as a ratio to the total nonvolatile components The minimum value of the absolute reflectance of the coating layer on one surface is in the range of 5.7 to 6.3% at an arbitrary wavelength of 400 to 800 nm, and the coating solution containing a release agent A laminated polyester film having a formed coating layer on the other surface. The laminated polyester film according to claim 1, wherein the coating liquid containing titanium oxide and a crosslinking agent contains a compound having a condensed polycyclic aromatic. The laminated polyester film according to claim 1 or 2 , wherein the coating liquid containing a release agent contains 18 to 38% by weight of a melamine compound as a ratio in a nonvolatile component .