JP2013086496A - Laminated polyester film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyester film that can be favorably utilized in applications requiring excellent adhesion, reduction of unevenness in interference due to reflection of outside light after various surface functional layers such as hard coat layers are formed, and reduction in the amount of precipitation of oligomers due to heating, for example, such as a transparent electrode film member for a touch panel or the like and a member for a molding film or the like.SOLUTION: A laminated polyester film has a coating layer which is formed of coating liquid containing metal oxide and two or more types of cross-linkers and in which the absolute reflectance of the surface of the coating layer has one minimum value in the wavelength range of 400-800 nm and the absolute reflectance at the minimum value is ≥4.0%, on one surface of a polyester film. The laminated polyester film also has a coating layer in which the amount of precipitation of oligomers (cyclic trimers) on the surface when subjected to heat treatment at 180°C and for ten minutes is ≤3.0 mg/m, on another surface.

Description

  TECHNICAL FIELD The present invention relates to a laminated polyester film. For example, adhesion to a surface functional layer such as a transparent electrode such as a touch panel or a film for molding, a hard coat layer, and interference unevenness due to reflection of external light and an oligomer caused by heating. (Cyclic trimer) The present invention relates to a laminated polyester film suitable for applications in which a reduction in the amount of precipitation is required.

  In recent years, polyester films are often used for various optical films and molding films. Transparent electrodes such as touch panels, which are members of various displays, antireflection films, prism sheets, light diffusion sheets, electromagnetic wave shielding films, It is used for applications such as mold transfer films and 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.

  An example of improving interference unevenness by increasing the refractive index of the coating layer is, for example, a method of combining a metal chelate compound having a high refractive index and a resin in the coating layer. In this case, the stability of the coating solution may not be sufficient depending on the combination due to the instability of the metal chelate in the aqueous solution, which may lead to an increase in the liquid exchange work when producing for a long time. . Moreover, when using a metal chelate compound, the adhesiveness with a hard-coat layer may fall if it carries out moisture-proof heat processing (patent document 1). Moreover, since a high refractive index material usually used is inferior in adhesion to a surface functional layer such as a hard coat layer, a coating layer that can effectively improve adhesion even when combined with a high refractive index material is required. Yes.

  In addition, for example, when the film is exposed to a high temperature, such as a touch panel conductive layer forming process or a heat treatment process for molding, oligomers (cyclic trimers) that are present in the polyester film of the substrate are deposited on the film surface. There is a problem of doing. When there is a lot of oligomer precipitation, it causes contamination in each process, and there are disadvantages such as when it looks whitish and the transparency becomes poor, so a film with less oligomer precipitation due to heating has been required. .

JP 2005-97571 A

  The present invention has been made in view of the above circumstances, and the problem to be solved is that the adhesion with a surface functional layer such as a hard coat layer and interference unevenness due to reflection of external light are reduced, and an oligomer (cyclic) by heating is reduced. (Trimer) It is to provide a laminated polyester film with a small amount of precipitation.

  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 coating layer formed from a coating solution containing a metal oxide and two or more kinds of crosslinking agents, and the absolute reflectance of the coating layer surface is minimal within a wavelength range of 400 to 800 nm. One surface of the polyester film having a coating layer having an absolute reflectance of 4.0% or more at the minimum value on one surface of the polyester film and heat-treated at 180 ° C. for 10 minutes. Trimer) The present invention resides in a laminated polyester film characterized by having a coating layer having a deposition amount of 3.0 mg / m ² or less 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 easy handling. 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, the dicarboxylic acid component of the copolyester includes isophthalic acid, phthalic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, adipic acid, sebacic acid, oxycarboxylic acid (for example, p-oxybenzoic acid, etc.), etc. 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, a titanium compound is preferable from the viewpoint of increasing the brightness of the film.

  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 slipperiness and preventing scratches in each step. 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 include inorganic particles such as magnesium, 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.

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 particle | grains is 5 micrometers or less normally, Preferably it is 0.01-3 micrometers, More preferably, it is the range of 0.05-2 micrometers. When the average particle diameter exceeds 5 μm, the surface roughness of the film becomes too rough, and a problem may occur when various surface functional layers are formed in the subsequent process.

  Further, the content of particles in the polyester layer is usually less than 5% by weight, preferably in the range of 0.0003 to 3% by weight. When there are no or few particles, the transparency of the film becomes high and the film becomes a good film, but the slipperiness may be insufficient. There are cases where improvement is required. Further, when the particle content exceeds 5% by weight, the transparency of the film may be insufficient.

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

  In addition to the above-mentioned particles, conventionally known antioxidants, 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 obtaining an unstretched sheet by cooling and solidifying a molten sheet extruded from a die with a cooling roll using pellets obtained by drying the polyester raw material described above using a single screw extruder 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 this invention, it is a coating layer formed from the coating liquid containing a metal oxide and two or more types of crosslinking agents, and the absolute reflectance of the surface of the coating layer has a minimum value of 1 in the wavelength range of 400 to 800 nm. And having a coating layer having an absolute reflectance of 4.0% or more at the minimum value (hereinafter sometimes abbreviated as a first coating layer) on one surface of the polyester film, and having a coating layer of 10 at 180 ° C. A coating layer (hereinafter sometimes abbreviated as a second coating layer) having an oligomer (cyclic trimer) deposition amount of 3.0 mg / m ² or less on the film surface when heat-treated for a minute is provided on the other surface. It is an essential requirement to have it.

  In the present invention, an oligomer is defined as a cyclic trimer among low molecular weight substances that crystallize and precipitate on the film surface after heat treatment.

  The first coating layer of the film of the present invention is designed to reduce interference unevenness due to external light after the surface functional layer such as a hard coat layer is formed, and is provided to improve the adhesion with the surface functional layer. is there.

  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, since the refractive index of the resin used in the coating layer is low, it is preferable to use a metal oxide having a high refractive index, and it is preferable to use a refractive index of 1.7 or more. 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. In particular, zirconium oxide is more preferably used from the viewpoint of weather resistance.

  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.

  In the present invention, the coating liquid for forming the first coating layer contains two or more kinds of crosslinking agents, but these are in close contact with a surface functional layer such as a hard coat layer provided on the coating layer. Can be improved. We have found that even one type of cross-linking agent can improve the adhesion, but by using two or more types of cross-linking agents together, the adhesion can be further improved, especially the adhesion after the wet heat test. I found what I could do.

  Examples of the crosslinking agent used for forming the first coating layer of the film of the present invention include oxazoline compounds, epoxy compounds, melamine compounds, isocyanate compounds, carbodiimide compounds, and silane coupling compounds. Among these crosslinking agents, from the viewpoint of good adhesion, it is particularly preferable to use an oxazoline compound or an epoxy compound, and it is more preferable to use an oxazoline compound and an epoxy compound in combination.

  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 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 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 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.

  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 the laminated polyester film in the first coating layer of the present invention, the coating appearance is improved, interference unevenness is reduced when various surface functional layers such as a hard coat layer are laminated on the coating surface, and transparency and adhesion are improved. For this reason, it is preferable to use various polymers in combination.

  Specific examples of the polymer include polyester resin, acrylic resin, urethane resin, polyvinyl (polyvinyl alcohol, polyvinyl chloride, vinyl chloride vinyl acetate copolymer, etc.), polyalkylene glycol, polyalkyleneimine, methylcellulose, hydroxycellulose, starches. Etc. 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, and quaternary ammonium salt, and a carboxyl group is preferred. As a method for introducing a carboxyl group into a urethane resin, various methods can be taken in each stage of the polymerization reaction. For example, there are a method of using a carboxyl group-containing resin as a copolymer component during prepolymer synthesis, and a method of using a component having a carboxyl group as one component such as polyol, polyisocyanate, and chain extender. In particular, a method in which a desired amount of carboxyl groups is introduced using a carboxyl group-containing diol depending on the amount of this component charged is preferred. For example, dimethylolpropionic acid, dimethylolbutanoic acid, bis- (2-hydroxyethyl) propionic acid, bis- (2-hydroxyethyl) butanoic acid and the like are copolymerized with a diol used for polymerization of a urethane resin. Can do. The carboxyl group is preferably in the form of a salt neutralized with ammonia, amine, alkali metal, inorganic alkali or the like. Particularly preferred are ammonia, trimethylamine and triethylamine. In such a polyurethane resin, a carboxyl group from which 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 first coating layer for the purpose of improving the adhesion and slipperiness of the coating layer. 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. 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 for the purpose of reducing the amount of oligomers deposited by heating, for example, for reducing the contamination in the heating step and each subsequent step, keeping the film white, and maintaining transparency. Is provided.

  As a material used for suppressing the amount of oligomer deposition on the film surface by heating, a compound having a chemical structure different from that of a polyester resin or a crosslinkable compound is effective. For example, a melamine compound, a quaternary ammonium salt compound, polyvinyl Examples include alcohol and various metal compounds.

  As the melamine compound, a compound that can be used for forming the first coating layer as described above can be used.

  The quaternary ammonium salt compound is a compound containing a quaternary ammonium salt in the molecule, for example, a pyrrolidinium ring, a quaternized alkylamine, and a copolymer of these with acrylic acid or methacrylic acid, Examples thereof include quaternized N-alkylaminoacrylamides, vinylbenzyltrimethylammonium salts, 2-hydroxy-3-methacryloxypropyltrimethylammonium salts, and the like. Further, these may be combined or copolymerized with other resins. In addition, examples of anions that serve as counter ions of these quaternary ammonium salts include ions such as halogen ions, sulfonates, phosphates, nitrates, alkylsulfonates, and carboxylates.

  Among the quaternary ammonium salt compounds, a compound having a pyrrolidinium ring is more preferable in terms of excellent heat stability.

  The compound having a pyrrolidinium ring is, for example, a polymer having a structure of the following formula (1).

In the above formula (1), each R ^1, R ² are independently an alkyl group, a phenyl group, these alkyl groups, a phenyl group may be substituted by the following groups. Substitutable groups are, for example, hydroxyl group, amide group, ester group, alkoxy group, phenoxy group, naphthoxy group, thioalkoxy, thiophenoxy group, cycloalkyl group, trialkylammonium alkyl group, cyano group, and halogen. R ¹ and R ² may be chemically bonded. For example, — (CH ₂ ) _m — (m is an integer of 2 to 5), —CH (CH ₃ ) CH (CH ₃ ) —, -CH = CH-CH = CH - , - CH = CH-CH = N -, - CH = CH-N = C -, - CH 2 OCH 2 -, - (CH 2) 2 O (CH 2) 2 - Etc.
Wherein X ^- represents a halogen ion, sulfonate, phosphate, nitrate, alkyl sulfonate, carboxylate and the like.

  In the present invention, the polymer of the above formula (1) is obtained by cyclopolymerizing a compound represented by the following formula (2) using a radical polymerization catalyst. The polymerization is carried out by using a polymerization initiator such as hydrogen peroxide, benzoyl peroxide, tertiary butyl peroxide in a polar solvent such as water or methanol, ethanol, isopropanol, formamide, dimethylformamide, dioxane, acetonitrile as a solvent. Although it can implement by a method, it is not limited to these. In the present invention, a compound having a polymerizable carbon-carbon unsaturated bond may be used as a copolymerization component.

  Moreover, the number average molecular weight of a quaternary ammonium salt compound is 1000-500000 normally, Preferably it is 2000-100000, More preferably, it is 5000-50000. When the molecular weight is less than 1000, the strength of the coating film may be weak or the heat resistance stability may be poor. On the other hand, when the molecular weight exceeds 500,000, the viscosity of the coating solution increases, and the handleability and applicability may deteriorate.

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

Various metal compounds are compounds containing metals, such as sodium chloride, sodium bromide, sodium carbonate, sodium nitrate, potassium chloride, potassium nitrate, strontium chloride, strontium nitrate, cesium chloride, cesium acetate, magnesium chloride. , Magnesium nitrate, calcium chloride, calcium nitrate, iron chloride (II), iron bromide (II), iron nitrate, potassium hexacyanoferrate (II), potassium hexacyanoferrate (III), cobalt chloride (II), bromide Cobalt (II), cobalt iodide (II), cobalt nitrate (II), cobalt acetate (II), cobalt sulfate (II), nickel chloride (II), nickel bromide (II), nickel nitrate (II), acetic acid Nickel (II), nickel sulfate (II), palladium (II) sodium chloride, copper (II) chloride, copper bromide (II), copper nitrate II), copper sulfate (II), silver nitrate, zinc chloride, zinc nitrate, zinc acetate, aluminum chloride, aluminum nitrate, indium chloride (III), metal salt compounds such as indium nitrate (III), titanium triethanolamate, titanium Examples include titanium chelate compounds such as lactate and titanium acetylacetonate, zirconium chelate compounds such as zirconium acetylacetonate, aluminum chelate compounds such as aluminum acetylacetonate, and metal chelate compounds such as cobalt chelate compounds such as cobalt acetylacetonate. .

  In the formation of the second coating layer of the film of the present invention, various polymers and crosslinking agents used for forming the first coating layer can be used in combination for improving the coating appearance and transparency. is there.

  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.

  Furthermore, as long as the gist of the present invention is not impaired, the first coating layer and the second coating layer have an antifoaming agent, coating property improving agent, thickening agent, organic lubricant, antistatic agent, ultraviolet absorption as necessary. Agents, antioxidants, foaming agents, dyes, pigments and the like may be contained.

  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 3-70 weight% normally, Preferably it is the range of 5-50 weight%. More preferably, it is in the range of 5 to 40% by weight, particularly preferably in the range of 8 to 30% by weight. When the amount of the metal oxide is less than 3% by weight, the refractive index of the coating layer cannot be made sufficiently high, so that interference unevenness may not be reduced. When it exceeds 70% by weight, the coating layer is transparent. Sexuality may worsen.

  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, 2 or more types of crosslinking agents are 2-80 weight% normally, More preferably, it is 4-60. It is in the range of wt%, more preferably in the range of 10-40 wt%. 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.

When an oxazoline compound is used as a crosslinking agent, the content of the oxazoline compound is usually in the range of 1 to 50% by weight, more preferably 1 to 30 as a ratio to the total nonvolatile components in the coating liquid forming the first coating layer. % By weight, more preferably in the range of 3-20% by weight.
If the amount is less than 1% by weight, there is a concern that the adhesion to the surface functional layer such as a hard coat layer may be lowered. If the amount exceeds 50% by weight, the refractive index of the coating layer is lowered, thereby causing a hard coat layer or the like. Visibility may not be good due to interference unevenness after the surface functional layer is formed.

  When using an epoxy compound as a crosslinking agent, the content of the epoxy compound is usually in the range of 1 to 50% by weight, more preferably 3 to 30 as a ratio to the total nonvolatile components in the coating liquid for forming the first coating layer. It is in the range of wt%, more preferably in the range of 5-20 wt%. If it is out of these ranges, there is a possibility that the adhesion with the surface functional layer such as the hard coat layer may be lowered, or the coating appearance may be deteriorated.

  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. Further, the content of the compound having a condensed polycyclic aromatic is preferably in the range of 80% by weight or less, and more preferably in the range of 5 to 70% by weight as a ratio to the total nonvolatile components in the coating liquid for forming the first coating layer. %, More preferably 10 to 50% 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.

  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 first coating layer provided on the polyester film is usually 0.04 to 0.20 μm, preferably 0.05 to 0.16 μm, more preferably 0.07 to 0. The range is 13 μm. When the film thickness is out of the above range, visibility may deteriorate due to interference unevenness after the surface functional layer is laminated.

  Regarding the laminated polyester film in the present invention, the thickness of the second coating layer provided on the polyester film is usually 0.001 to 1.0 μm, preferably 0.01 to 0.3 μm, more preferably 0.02 to 0. .2 μm range. When the film thickness is out of the above range, the oligomer precipitation preventing property and the coating appearance may be deteriorated.

  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 film of the present invention has a refractive index adjusted to suppress the occurrence of interference unevenness, and the refractive index of the surface functional layer such as a polyester film and a hard coat layer as a base material It is designed around the geometric mean. The refractive index of the coating layer and the reflectance of the coating layer are closely related. The absolute reflectance of the film of the present invention is a graph in which the horizontal axis indicates the wavelength and the vertical axis indicates the reflectance, and the minimum value of the reflectance needs to be one in the wavelength range of 400 to 800 nm. Is 4.0% or more. In the range of the absolute reflectance of the present invention, if the minimum value appears at the same wavelength, the reflectance of the minimum value is a high value when the refractive index is high, and a low value when the refractive index is low.

  The absolute reflectance of the first coating layer in the film of the present invention has one minimum value in the wavelength range of 400 to 800 nm, more preferably one minimum value in the wavelength range of 500 to 700 nm. The minimum value is preferably in the range of 4.0 to 6.5%, more preferably 4.5 to 6.2%. If the minimum value in the wavelength range of 400 to 800 nm is not one, and if the absolute reflectance of the minimum value deviates from the above value, interference unevenness occurs after the surface functional layer such as a hard coat layer is formed. The visibility of the film may be reduced.

  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.

The amount of oligomer precipitation in the second coating layer in the film of the present invention is a method of extracting from the surface of the second coating layer with dimethylformamide after heat treatment (180 ° C., 10 minutes), and the amount of oligomer is 3.0 mg / m ^2. Or less, preferably 1.5 mg / m ² or less, more preferably 1.0 mg / m ² or less. When the amount of the oligomer exceeds 3.0 mg / m ² , there is a concern about deterioration of transparency and contamination of the process due to whitening of the film in various heating processes.

  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) Method for measuring the intrinsic viscosity of polyester 1 g of polyester from which other polymer components and pigments incompatible with polyester have been removed are precisely weighed, 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 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. .

(3) 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).

(4) 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 wavelength (bottom wavelength) and reflectance at the minimum value were evaluated.

(5) Interference unevenness evaluation method On the first coating layer side of the polyester film, 72 parts by weight of dipentaerythritol hexaacrylate, 18 parts by weight of 2-hydroxy-3-phenoxypropyl acrylate, 10 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. The obtained film is visually observed under a three-wavelength fluorescent lamp, and interference unevenness is observed. If the interference unevenness is not confirmed, ◎, thin sparse interference unevenness is confirmed, thin, linear The case where the interference unevenness was confirmed was indicated by Δ, and the case where clear interference unevenness was confirmed was indicated by ×.

(6) Method for evaluating the adhesion of the first coating layer In order to perform a more stringent evaluation of the adhesion, examination was made with materials obtained by removing antimony pentoxide from the hard coat solution used in the evaluation of (5) above. That is, 80 parts by weight of dipentaerythritol hexaacrylate, 20 parts by weight of 2-hydroxy-3-phenoxypropyl acrylate, 5 parts by weight of a photopolymerization initiator (trade name: Irgacure 184, manufactured by Ciba Specialty Chemicals), 200 parts by weight of methyl ethyl ketone The mixed coating solution was applied so that the dry film thickness was 5 μm, and cured by irradiating with ultraviolet rays to form a hard coat layer. The obtained film was subjected to 10 × 10 cross-cut after 100 hours in an environment of 80 ° C. and 90% RH, and then a 18 mm wide tape (cello tape (registered trademark) CT manufactured by Nichiban Co., Ltd.). -18) is pasted and the peeled surface is observed after being peeled off rapidly at a peeling angle of 180 °. If the peeled area is less than 3%, ◎ if it is 3% 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.

(7) Measuring method of oligomer precipitation amount precipitated on the surface of the second coating layer The polyester film is heated in air at 180 ° C. for 10 minutes. Thereafter, the heat-treated film is formed in a box shape with the second 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 (dimethylformamide) was placed in the box prepared by the above method and allowed to stand for 3 minutes, after which DMF was recovered and subjected to liquid chromatography (manufactured by Shimadzu Corporation: LC-7A, mobile phase A: acetonitrile. , Mobile phase B: 2% aqueous acetic acid solution, column: “MCI GEL ODS 1HU” manufactured by Mitsubishi Chemical Corporation, column temperature: 40 ° C., flow rate: 1 ml / min, detection wavelength: 254 nm) The amount of oligomer was determined, and this value was divided by the film area with which DMF was contacted to obtain the amount of oligomer on the film surface (mg / m ² ). The amount of oligomer 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 an oligomer (cyclic trimer) collected in advance and dissolving it in DMF accurately weighed.

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 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. 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)>
In the production method of polyester (A), polyester (C) is obtained using the same method as the production method of polyester (A), except that 0.3 part by weight of silica particles having an average particle diameter of 2 μm is added before melt polymerization. It was.

Examples of compounds constituting the coating layer are as follows.
(Example compounds)
Metal oxide: (IA) Zirconium oxide particles having an average particle diameter of 15 nm Metal oxide: (IB) Titanium oxide particles having an average particle diameter 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)
・ Oxazoline compounds: (IIB)
Acrylic polymer having oxazoline group and polyalkylene oxide chain Epocros WS-700 (Nippon Shokubai Co., Ltd., VOC free type)

Epoxy compound: (IIIA) Denacol EX-521 (manufactured by Nagase ChemteX Corporation), which is polyglycerol polyglycidyl ether.
Epoxy compound: (IIIB) Denacol EX-1410 (manufactured by Nagase ChemteX Corporation), which is an epoxy resin.

・ Condensed polycyclic aromatic polyester resin: (IVA)
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: (IVB)
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%)

Acrylic resin: (IVC) Aqueous dispersion of acrylic resin polymerized with the following composition: ethyl acrylate / n-butyl acrylate / methyl methacrylate / N-methylol acrylamide / acrylic acid = 65/21/10/2/2 (% by weight) Emulsion polymer (emulsifier: anionic surfactant)

・ Urethane resin (IVD)
Hydran AP-40 (manufactured by DIC Corporation), which is a carboxylic acid water-dispersed polyester polyurethane resin

・ Hexamethoxymethylmelamine (V)

・ Particles: (VIA) Silica particles with an average particle size of 0.07 μm ・ Particles: (VIB) Silica particles with an average particle size of 0.15 μm ・ Particles: (VIC) Alumina-modified silica particles with an average particle size of 0.02 μm

・ Quaternary ammonium salt compound: (VII)
Polymer polymerized with the following composition having a pyrrolidinium ring in the main chain: Diallyldimethylammonium chloride / dimethylacrylamide / N-methylolacrylamide = 90/5/5 (mol%). Number average molecular weight of about 30,000.
・ Polyvinyl alcohol resin: (VIII)
Polyvinyl alcohol having a saponification degree of 88 mol% and a polymerization degree of 500.

Example 1:
A mixed raw material in which polyesters (A) and (B) 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), (B), and (C) are 89% and 5%, respectively. % And 6% mixed raw materials were used as intermediate layer raw materials, each was supplied to two extruders, melted at 285 ° C., and then on a cooling roll set at 40 ° C. Coextruded with a layer structure of layers (surface layer / intermediate layer / surface layer = 1: 18: 1 discharge amount) and cooled and 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 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 After the heat treatment, the film is relaxed by 2% in the lateral direction, and the coating layer having the first coating layer thickness (after drying) of 0.10 μm and the second coating layer thickness (after drying) of 0.03 μm A polyester film having a thickness of 100 μm was obtained.

  When the obtained polyester film was evaluated, the absolute reflectance of the first coating layer was measured. As a result, the minimum value was 600 nm and the reflectance was 5.0%. There was no clear interference unevenness and good adhesion. Moreover, the oligomer precipitation amount of the 2nd application layer was low and favorable. The properties of this film are shown in Tables 3 and 4 below.

Examples 2-25:
In Example 1, it manufactured like Example 1 except having changed the coating composition into the coating composition shown in Table 1 and Table 2, and obtained the polyester film. As shown in Tables 3 and 4, the finished polyester film had good adhesion and interference unevenness level of the first coating layer, and the oligomer deposition amount of the second coating layer was low and good.

Comparative Examples 1-6:
In Example 1, it manufactured like Example 1 except having changed the coating composition into the coating composition shown in Table 1 and Table 2, and obtained the polyester film. When the finished laminated polyester film was evaluated, as shown in Tables 5 and 6 below, when the adhesion is inferior, there is a concern that clear interference unevenness can be observed, the oligomer precipitation amount is high, and whitening or the like occurs in the heating step. There was something.

Comparative Example 7:
In Example 1, it manufactured similarly to Example 1 except not providing a 2nd coating layer, and obtained the polyester film. When the completed laminated polyester film was evaluated, as shown in Tables 5 and 6 below, the amount of oligomer precipitation was high.

  The film of the present invention requires, for example, adhesion with a surface functional layer such as a hard coat layer such as a transparent electrode such as a touch panel or a molding film, reduction of interference unevenness due to reflection of external light, and reduction of the amount of oligomer precipitation by heating. It can utilize suitably for the use used.

Claims (1)

It is a coating layer formed from a coating liquid containing a metal oxide and two or more kinds of crosslinking agents, and the absolute reflectance of the coating layer surface has one minimum value in the wavelength range of 400 to 800 nm, Having a coating layer having an absolute reflectance of 4.0% or more at the minimum value on one side of the polyester film, the amount of oligomer (cyclic trimer) deposited on the surface when heat-treated at 180 ° C. for 10 minutes is 3 A laminated polyester film having a coating layer on the other side of 0.0 mg / m ² or less.