JP2014193998A - Laminated polyester film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyester film which can be suitably used in applications which require reduction of interference unevenness caused by external light reflection after formation of various functional surface layers such as an excellent transparent layer or hard coat layer, the applications including, for example, a film member for a transparent electrode such as a touch panel and a member such as a film for molding.SOLUTION: Provided is a laminated polyester film having a coating layer formed from a coating liquid containing non-heat-resistant particles and a condensed polycyclic aromatic compound on at least one surface of the polyester film.

Description

  The present invention relates to a laminated polyester film, and particularly has excellent transparency, for example, reduction of interference unevenness due to reflection of external light such as a hard coat film used in a transparent electrode such as a touch panel or a film for molding. The present invention relates to a laminated polyester film suitable for applications requiring easy handling.

  Because polyester film has excellent transparency and strength, it is used as a base material for touch panels, prism lens films, microlens films, light diffusion films, antireflection films, hard coat films, electromagnetic shielding films, moldings, etc. Yes. In recent years, especially for films used for forming surface functional layers including hard coat layers, such as display members such as touch panels, in-mold transfer films, in-mold label films, etc., more excellent transparency It is being sought.

  Conventionally, a technique of incorporating particles into a polyester film for the purpose of easy slipping has been common (Patent Documents 1 and 2). However, in the case of the method of incorporating particles in the polyester film, the haze of the film becomes high and becomes whitish, or when observed under a fluorescent lamp, graininess due to the particles is seen and visibility is deteriorated. May end up.

  In order to solve these problems, a film that does not contain particles in a polyester film has also been proposed (Patent Document 3). However, in the case of a film containing no particles, there is a drawback that the slipperiness is poor and the film is easily damaged. A proposal has been made to form a coating layer containing particles on a uniaxially stretched polyester film to impart slipperiness. However, before the coating layer is formed, the slipperiness cannot be improved, and it is applied from film formation by melt extrusion. In the meantime, the slipperiness is poor and scratches are inevitable.

  In order to impart higher performance, various surface functional layers are usually formed on the polyester film. In recent years, clear hard coat processing has been increasingly performed on members of touch panels and molding members. In order to improve the adhesion between the polyester film 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.

  If a film with uneven interference is used for a molding member such as a display such as a touch panel or a casing of a mobile phone that requires a design, the visibility becomes poor and the film becomes 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.

JP 2006-169467 A JP 2006-77148 A JP 2000-229355 A

  The present invention has been made in view of the above circumstances, and the problem to be solved is that it has excellent transparency, good slipperiness, adhesion to various surface functional layers such as a hard coat layer, and the like. An object of the present invention is to provide a laminated polyester film excellent in reducing interference unevenness due to light reflection.

  As a result of intensive studies in view of the above circumstances, the present inventors have found that the use of a 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 characterized by having a coating layer formed from a coating solution containing a compound having non-heat-resistant particles and a condensed polycyclic aromatic compound on at least one side of the polyester film. Exist.

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

  The polyester film constituting the 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 the gist of the present invention is not exceeded other than the two-layer or three-layer structure. It may be a multilayer and is not particularly limited. For example, it is possible to change the raw material of the surface layer and the intermediate layer into a three-layer structure for the purpose of effectively improving various properties using a polyester film with high functionality as the surface layer raw material.

  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, 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.

  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 diameter exceeds 3 μm, the film brightness decreases when the transparency of the film deteriorates, when the graininess due to the particles occurs and the visibility deteriorates, or when light scattering by the particles occurs. There is a case.

  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). If it exceeds 1000 ppm, the transparency may deteriorate, the graininess caused by particles may occur and the visibility may deteriorate, or the brightness of the film may decrease due to light scattering by the particles.

  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.

  The polyester film of the present invention may contain an ultraviolet absorber in order to improve the weather resistance of the film, for example, to prevent deterioration of the liquid crystal or the like 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 film of the present invention, conventionally known antioxidants, antistatic agents, thermal stabilizers, lubricants, dyes, pigments, etc. may be added to the polyester film in the present invention as necessary in addition to the above-mentioned particles and ultraviolet absorbers. Can do.

  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 drying the polyester raw material pellets described above and cooling and solidifying the molten film extruded from the die with a cooling roll using a single screw extruder is preferable. In this case, in order to improve the flatness of the film, it is preferable to improve the adhesion between the film and the rotary cooling drum, and an electrostatic application adhesion method or a liquid application adhesion method is preferably employed. Next, the obtained unstretched film is stretched in the biaxial direction. In that case, first, there is a method in which a coating solution containing non-heat-resistant particles is applied to the unstretched film and dried to form a coating layer. Thereafter, the film is stretched in one direction by a roll or 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 polyester film. In the simultaneous biaxial stretching method, a coating solution containing non-heat-resistant particles is applied to the unstretched film, and the machine direction and the width direction are usually controlled at 70 to 120 ° C., preferably 80 to 110 ° C. The stretching ratio is 4 to 50 times, preferably 7 to 35 times, and more preferably 10 to 25 times. 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.

  In the present invention, it is an essential requirement to have a coating layer formed from a coating solution containing a compound having non-heat-resistant particles and a condensed polycyclic aromatic on at least one surface of a polyester film.

  The present inventors include particles in a polyester film, and as a method for ensuring transparency and slipperiness, a change in the average particle diameter of the particles, a change in the addition amount of the particles, a layer of the polyester film containing the particles ( In the three-layer structure, only the outermost layer contains particles, and while improving the transparency, the method of changing the thickness of the slippery) has been studied, but both ensure high transparency and sufficient slipperiness. It was a difficult result.

  As one of the objects of the present invention, by forming the coating layer at the initial stage of the film production process, in various processes from the formation of the coating layer on the unstretched film formed after the melt extrusion until before the high temperature treatment. It is used to ensure sufficient slipperiness.

  In addition, usually when particles are present, they appear whitish due to light scattering, but when non-heat-resistant particles are used, they can be melted at a high temperature to reduce the particle size, deform, or be eliminated in a later step. In addition, they found that it was possible to reduce whitishness and realized high transparency.

  The formation of the coating layer in the film of the present invention may be provided by in-line coating, which treats the film surface during the process of forming a polyester film, or is applied off-system on a once produced film. Is also possible. In-line coating is preferred because it can be applied at the same time as film formation and the production cost can be kept low. Among these, in order to heat-treat the non-heat resistant particles and make them highly transparent, it is more preferable to carry out at any stage from after the unstretched film formed after melt extrusion to before high temperature treatment. In particular, in order to prevent damage due to the roll, it is preferable to carry out at an initial stage. Moreover, in the method of extending | stretching by making it contact with films, such as a roll, since the damage to a film becomes large, forming in the step before extending | stretching is preferable.

  Furthermore, in order to increase transparency, it is necessary to treat at a temperature higher than the heat-resistant temperature (temperature at which heat is deformed) in order to reduce, deform, or eliminate the particle size by melting the non-heat-resistant particles in the subsequent process. Is preferable.

  The coating layer in the film of the present invention is not limited to the following. For example, in sequential biaxial stretching, after forming an unstretched film, a coating layer is formed at an initial stage, and then the first stretching is performed. A more suitable polyester film can be manufactured by performing high temperature treatment after performing the second stretching. The place where the coating layer is formed is not limited to the above. For example, in the case of sequential biaxial stretching, the coating layer may be formed at the stage after the first stretching and before the second stretching. Also good.

  The coating layer in the film of the present invention may be formed on only one side of the film or may be formed on both sides in order to overcome, for example, a more easily damaged area. Moreover, in the case of both surfaces, the formation location may be the same or different.

  The non-heat resistant particles used in the present invention are particles having low heat resistance, and the particles are deformed at a high temperature. In particular, in the production process of the polyester film, the particles are deformed or dissolved in a process in which the temperature after film formation is high. However, for example, when selecting a method of stretching in contact with a film such as a roll in the first stretching, it is necessary to maintain a sufficient shape as particles in order to exhibit slipperiness in the stretching process. Some heat resistance is necessary.

  That is, the thermal characteristics required for the non-heat resistant particles are preferably those that do not undergo thermal deformation at a temperature of less than 120 ° C. and that undergo thermal deformation at a temperature of 120 ° C. or higher.

  The softening point of the non-heat resistant particles is preferably in the range of 120 to 270 ° C, more preferably in the range of 150 to 250 ° C, and still more preferably in the range of 180 to 230 ° C. When the temperature is lower than 120 ° C., when a method of stretching by contacting with a film such as a roll in the first stretching is selected, depending on the stretching temperature, thermal deformation of the particles may occur, and the slipping property is deteriorated. There are concerns. On the other hand, if the temperature exceeds 270 ° C., the final product may be a film in which the particles are not thermally deformed and remain whitish.

  The non-heat resistant particle is not particularly limited as long as it can maintain the above-mentioned thermal characteristics, but in general, the organic particles, i.e. Heat-resistant organic particles are preferred. In consideration of control of the size and shape of the particles and dispersibility in various solvents including water, the organic particles are more preferably of a high molecular type, that is, non-heat resistant polymer particles.

  As the non-heat-resistant polymer particles, cross-linked or non-cross-linked polymer particles can be used as long as the gist of the present invention is not impaired, but in order to make the thermal characteristics more suitable for the purpose of the present invention. More preferably, it is a non-crosslinked type, that is, a non-heat resistant non-crosslinked polymer particle.

  The non-crosslinking in the non-heat resistant non-crosslinked polymer particles is a polymer particle that does not have a three-dimensional structure or has a small number of heat resistance. For example, in the case of particles made of a polymerizable monomer as described later, the crosslinkable polymerizable monomer is preferably less than 5% by weight of the entire polymerizable monomer, and more preferably in the range of less than 1% by weight.

  As the polymer of the non-heat-resistant non-crosslinked polymer particles, conventionally known compounds can be used. For example, acrylic resin, styrene resin, vinyl resin, epoxy resin, urea resin, phenol resin, polyester resin, polyurethane resin , Polycarbonate resin, polyether resin and the like. Among these polymers, an acrylic resin, a styrene resin, and a vinyl resin formed from a polymerizable monomer having a carbon-carbon double bond are more preferable from the viewpoint that a compound having a desired thermal characteristic can be easily produced. In addition, in the case of these resins, since they are thermally deformed by high-temperature treatment, it is possible to prevent the particles from falling off. Furthermore, not only the function as particles, but also, for example, adhesion to various surface functional layers formed thereon It is also possible to develop other performances such as increasing.

  The polymerizable monomer having a carbon-carbon double bond refers to various carboxyl group-containing monomers such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid, fumaric acid, maleic acid, citraconic acid, and salts thereof; 2 -Various hydroxyl group-containing monomers such as hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, monobutylhydroxyfumarate, monobutylhydroxyitaconate; Various (meth) acrylates such as (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, lauryl (meth) acrylate; (meth) acrylamide, diacetone acrylamide, N -Methylol Various nitrogen-containing compounds such as chloramide or (meth) acrylonitrile; various styrene derivatives such as styrene, α-methylstyrene, divinylbenzene, vinyltoluene, various vinyl esters such as vinyl propionate; γ-methacrylic Various silicon-containing polymerizable monomers such as loxypropyltrimethoxysilane, vinyltrimethoxysilane, etc .; phosphorus-containing vinyl monomers; various vinyl halides such as vinyl fluoride, vinyl chloride, and biridene chloride; butadiene And various conjugated dienes.

  Among these, an acrylic resin obtained by polymerizing a (meth) acrylic polymerizable monomer as a main component is optimal. Also, a styrene / acrylic resin having a (meth) acrylic polymerizable monomer as a main component and copolymerized with a styrene derivative can be suitably used.

  That is, in the film of the present invention, the best form of the non-heat-resistant particles used for forming the coating layer is the non-heat-resistant non-crosslinked acrylic resin particles and the non-heat-resistant non-crosslinked styrene / acrylic resin particles as described above. .

  When non-heat resistant non-crosslinked acrylic resin particles are used, the glass transition point of the resin particles is preferably in the range of 0 to 150 ° C, more preferably in the range of 50 to 120 ° C. When the temperature is lower than 0 ° C, there is a concern that the slipperiness cannot be sufficiently exhibited. When the temperature exceeds 150 ° C, there is a concern that the thermal deformation of the particles is not sufficient.

  The average particle diameter of the non-heat-resistant particles depends on the film thickness and cannot be generally specified, but is preferably in the range of 0.01 to 3 μm, more preferably in the range of 0.03 to 1 μm, and still more preferably 0.00. It is the range of 05-0.5 micrometer. When the average particle size is less than 0.01 μm, the slipperiness may not be sufficiently obtained. When the average particle size exceeds 3 μm, the particles are not sufficiently deformed and a whitish film remains. May end up.

  In the present invention, mainly for the purpose of increasing the refractive index of the coating layer in order to reduce interference unevenness due to external light reflection after various surface functional layers such as a hard coat layer are formed. For the formation, a compound having a condensed polycyclic aromatic is used.

  The compound having a condensed polycyclic aromatic is, for example, a compound having a structure such as naphthalene, anthracene, phenanthrene, naphthacene, benzo [a] anthracene, benzo [a] phenanthrene, pyrene, benzo [c] phenanthrene, and perylene. Can be mentioned.

  In consideration of applicability on a polyester film and adhesion to various surface functional layers, 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 manufacturing process, the condensed polycyclic aromatic used for forming the coating layer is preferably a compound having a naphthalene structure in that it is difficult to be colored. In addition, a resin in which a naphthalene skeleton is incorporated as a polyester component 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 skeleton include 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, and the like.

  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.

  Various types of coating layers are used to improve coating appearance, reduce interference unevenness when various surface functional layers such as hard coat layers are formed on the coating surface, and improve transparency and adhesion. It is also possible to use a polymer in combination. Examples of the polymer other than the compound having a condensed polycyclic aromatic as described above, for example, polyester resin, acrylic resin, urethane resin, polyvinyl (polyvinyl alcohol, etc.), polyalkylene glycol, polyalkyleneimine, methylcellulose, hydroxycellulose , Starches and the like. Among these, polyester resin, acrylic resin, and urethane resin are mentioned from the viewpoint of improving adhesion with a surface functional layer such as a hard coat layer and improving the appearance of coating.

  In forming the coating layer, it is preferable to use a cross-linking agent in order to strengthen the coating film of the coating layer, to improve adhesion to various surface functional layers, and to improve wet heat resistance. Examples of the crosslinking agent include oxazoline compounds, isocyanate compounds, carbodiimide compounds, epoxy compounds, melamine compounds, aziridine compounds, and silane coupling compounds. Among these crosslinking agents, an oxazoline compound, an isocyanate compound, a carbodiimide compound, and an epoxy compound are preferable from the viewpoint that adhesion after heat-resistant heat treatment is improved. In order to improve adhesion to various surface functional layers, it may be preferable to use two or more kinds of the above-mentioned crosslinking agents 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 content of the oxazoline group contained in the oxazoline compound is usually 0.5 to 10 mmol / g, preferably 1 to 9 mmol / g, more preferably 3 to 8 mmol / g, and further preferably 4 to 6 mmol in terms of the amount of the oxazoline group. / G. Use within the above range is preferable because adhesion to various surface functional layers is improved.

  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. Compound, methyl isobutanoyl acetate, ethyl isobutanoyl acetate, dimethyl malonate, diethyl malonate, methyl acetoacetate, ethyl acetoacetate, ethyl acetoacetate, mercaptan compounds such as butyl mercaptan, dodecyl mercaptan, ε-caprolactam, δ -Lactam compounds such as valerolactam, amine compounds such as diphenylaniline, aniline, and ethyleneimine, acetanilide, acetic acid acetate Examples include amide acid amide compounds, formaldehyde, acetoaldoxime, acetone oxime, methyl ethyl ketone oxime, oxime compounds such as 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 used for improving adhesion with a surface functional layer such as a hard coat layer that can be formed on a coating layer, and for improving wet heat resistance of the coating layer. It is what The carbodiimide compound is a compound having one or more carbodiimide or carbodiimide derivative structures in the molecule, but a polycarbodiimide compound having two or more in the molecule is more preferable for better adhesion and the like.

  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 content of the carbodiimide group contained in the carbodiimide-based compound is a carbodiimide equivalent (weight of the carbodiimide compound to give 1 mol of carbodiimide group [g]) and is usually 100 to 1000, preferably 250 to 800, more preferably 300. It is -700, More preferably, it is the range of 350-650. Use within the above range is preferable because adhesion to various surface functional layers is improved.

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

  The melamine compound is a compound having a melamine skeleton in the compound. For example, an alkylolized 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 the final film, heat-resistant particles can be used in combination for the purpose of blocking and improving slipperiness. The average particle diameter is preferably in the range of 0.5 μm or less, more preferably in the range of 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, heat-resistant organic particles, and the like.

  Regarding the formation of a coating layer in the film of the present invention, a coating solution prepared by adjusting the above-described series of compounds as a solution or solvent dispersion to a solid content concentration of about 0.1 to 80% by weight as a guide is applied to an unstretched polyester film. It is preferable to produce a polyester film in the manner of application to the substrate. In consideration of being in-line in particular, an aqueous solution or a water dispersion is more preferable, but the coating liquid contains an organic solvent for the purpose of improving the dispersibility in water and improving the film forming property. May be. Moreover, only one type of organic solvent may be used, and two or more types may be used as appropriate.

The amount of the non-heat resistant particles constituting the coating layer in the film of the present invention is not particularly limited as long as the object is achieved. Moreover, since it depends on the thermal characteristics, size, and coating layer thickness of the particles to be used, it cannot be said unconditionally, but as a quantity on only one side, it is a film after drying (before stretching), preferably 0.01 to range of 200 mg / ^{m 2,} more preferably from 0.1~150mg / ^{m 2,} more preferably in the range of 1~70mg / ^{m 2.}

The coating amount of the coating layer (after drying and before stretching) is only on one side and depends on the size of the particles, the stretching ratio, the coating position, etc. 5 g / ^{m 2} or less, more preferably in the range 0.4~3g / ^{m 2} range, more preferably in the range of 1.0 to 2.5 g / ^{m 2.} When the coating amount is out of the above range, there is a concern about blocking, deterioration of coating appearance, dropout of particles, and deterioration of interference unevenness due to external light reflection after forming the surface functional layer.

  Regarding the polyester film in the present invention, the final film thickness of the coating layer provided on the polyester film is usually 0.04 to 0.20 μm, preferably 0.05 to 0.16 μm, more preferably as a film after drying and stretching. Is in the range of 0.07 to 0.13 μm. When the film thickness is out of the above range, the visibility may be deteriorated due to interference unevenness due to external light reflection after the surface functional layer is formed.

  In the film of the present invention, as a method for forming the coating layer, for example, gravure coating, reverse roll coating, die coating, air doctor coating, blade coating, rod coating, bar coating, curtain coating, knife coating, transfer roll coating, squeeze Conventionally known coating methods such as coating, impregnation coating, kiss coating, spray coating, calendar coating, extrusion coating, etc. can be used.

  Moreover, when forming a coating layer in a film, you may perform surface treatments, such as a corona treatment and a plasma treatment, as needed.

  Moreover, in this invention, it is also possible to form a coating layer (2 layer structure) further on the coating layer of the film of this invention. For example, after forming the coating layer of the film of the present invention and stretching in at least one direction, the second coating layer can be formed in order to impart various performances. Further, the second coating layer can be formed on the side opposite to the surface on which the coating layer of the film of the present invention is formed. Moreover, you may form only in the single side | surface side of a film, and may form in both surfaces. Furthermore, the second coating layer can be the coating layer of the present invention.

  Furthermore, within the range not impairing the gist of the present invention, the above-mentioned coating layer is formed with heat-resistant particles, antifoaming agent, coating property improving agent, thickener, organic lubricant, antistatic agent, ultraviolet ray as necessary. Absorbers, antioxidants, foaming agents, dyes, pigments and the like can be used.

As a ratio with respect to the total non-volatile components in the coating solution for forming the coating layer, the non-heat-resistant particles cannot be generally described because they depend on the particle size and the film thickness, but are usually in the range of 0.01 to 50% by weight, Preferably it is the range of 0.1-20 weight%, More preferably, it is the range of 0.3-10 weight%. If it is out of the above range, if the sliding property is not sufficient, there is a concern that the transparency is not sufficient, the interference unevenness due to the reflection of external light after forming the surface functional layer due to the low refractive index of the coating layer may deteriorate. is there.

  As a ratio with respect to the total nonvolatile components in the coating solution for forming the coating layer, the compound having a condensed polycyclic aromatic is usually in the range of 10 to 99.99% by weight, preferably in the range of 20 to 98% by weight, more preferably. Is in the range of 30 to 95% by weight. When outside the above range, there may be cases where interference unevenness due to reflection of external light after forming a surface functional layer such as a hard coat layer is not sufficiently reduced.

  As a ratio with respect to all nonvolatile components in the coating solution for forming the coating layer, the crosslinking agent is usually in the range of 80% by weight or less, preferably in the range of 1 to 70% by weight, more preferably in the range of 3 to 50% by weight. . When used within the above range, adhesion to a surface functional layer such as a hard coat layer is improved.

  Analysis of the final form of the non-heat-resistant particles used for forming the coating layer and other components in the coating layer can be performed by, for example, TOF-SIMS, ESCA, fluorescent X-ray, various surface / cross-sectional observations, and the like. it can.

  The polyester film in the present invention can be used for applications requiring excellent transparency, and its internal haze is preferably in the range of 0.0 to 1.0%, more preferably 0.0 to 0.5%. More preferably, it is 0.0 to 0.3% of range. When the internal haze exceeds 1.0%, even if various surface functional layers are provided on the film, the haze cannot be sufficiently lowered, and the whitish color remains as a film. Cannot be achieved.

  The haze of the polyester film in the present invention cannot be generally stated when various surface functional layers are provided on the film because the surface haze can be lowered, but is preferably in the range of 0.0 to 2.0%, more preferably. Is in the range of 0.0 to 1.5%, more preferably in the range of 0.0 to 1.0%. If it exceeds 2.0%, the appearance of the film may be poor, or even if various surface functional layers are provided, the haze cannot be lowered sufficiently, and the visibility may be insufficient.

  The coating layer in the present invention has a refractive index adjusted in order to suppress occurrence of interference unevenness, and the refractive index (1.55 to 1.65) is a base polyester film (1.60 to 1.60). 1.70) and near the geometric mean of the refractive indices (1.45-1.65) of the surface functional layer such as the hard coat layer. The refractive index of the coating layer and the reflectance of the coating layer are closely related. The absolute reflectance of the coating layer of the film of the present invention is a graph showing the wavelength on the horizontal axis and the reflectance on the vertical axis, and the minimum value of the reflectance is one in the wavelength range of 400 to 800 nm. Is preferably 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 coating layer in the present invention is preferably such that one minimum value exists in the wavelength range of 400 to 800 nm, more preferably one minimum value exists 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 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.

  In addition, since the surface functional layer such as the hard coat layer has a high refractive index of the polyester film serving as the base material, it may be preferable to design it high particularly in order to reduce interference unevenness. One method for increasing the refractive index is to use a metal oxide. As the metal oxide, a conventionally known metal oxide can be used. For example, zirconium oxide, titanium oxide, tin oxide, acid value yttrium, antimony oxide, indium oxide, zinc oxide, antimontin oxide, indium tin oxide Etc. Among these, zirconium oxide is preferable in consideration of environmental aspects, weather resistance, and price.

  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 a surface functional layer such as a hard coat layer, a general wet coat method such as a roll coat method or a die coat method is employed when an organic material is used. 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 refractive index of the surface functional layer formed on the coating layer is generally 1.45 to 1.65 as described above.

  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 of particles The film was observed using an electron microscope (S-4500 manufactured by HITACHI), and the average value of the particle diameters of 10 particles was defined as the average particle diameter. The non-heat resistant particles were observed on the film before the high temperature process, that is, after the longitudinal stretching and before the transverse stretching.

(3) Measuring method of internal haze Using haze meter HZ-2 manufactured by Suga Test Instruments Co., Ltd., the film was immersed in ethanol and measured according to JIS K 7136.

(4) Measuring method of haze It measured by JISK7136 using the haze meter HM-150 by Murakami Color Research Laboratory.

(5) Film surface roughness (Sa)
Using a three-dimensional non-contact surface shape measurement system (MN537N-M100, manufactured by Ryoka System Co., Ltd.), the roughness Sa of the film on the cooled and solidified surface side before the high-temperature process, that is, after the longitudinal stretching and before the transverse stretching is determined. It was measured. When the Sa is less than 5 nm, the slipperiness is poor, and there is a concern that scratches may occur when coming into contact with a roll or the like in a stretching process or the like. A more preferable form is 5 nm or more.

(6) Transparency evaluation method When the film is visually observed under a three-wavelength light region type fluorescent lamp, the particle feeling (dots due to 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.

(7) Evaluation method of absolute reflectance from coated layer surface in polyester film A black tape (vinyl tape VT-50 manufactured by Nichiban Co., Ltd.) was previously applied to the measurement back surface of the polyester film, and a spectrophotometer (manufactured by JASCO Corporation). UV-visible 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, scanning The absolute reflectance of the coating layer surface in the wavelength range of 400 to 800 nm was measured at a speed of 1000 m / min, and the wavelength (bottom wavelength) and reflectance at the minimum value were evaluated.

(8) Interference unevenness evaluation method On a polyester film coating layer, 72 parts by weight of dipentaerythritol hexaacrylate, 18 parts by weight of 2-hydroxy-3-phenoxypropyl acrylate, 10 parts by weight of zirconium oxide, a photopolymerization initiator (product) Name: Irgacure 184, manufactured by Ciba Specialty Chemicals Co., Ltd.) 1 part by weight of a mixed coating solution of 200 parts by weight of methyl ethyl ketone was applied so as to have a dry film thickness of 5 μm, and cured by irradiation with ultraviolet rays to form a hard coat layer. . 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 ×.

(9) Adhesiveness evaluation method of coating layer With respect to the film on which the hard coat layer obtained by the evaluation in (8) above was formed, after 10 hours in an environment of 80 ° C. and 90% RH, Cross-cut, paste 18mm wide tape (Cello Tape (registered trademark) CT-18 manufactured by Nichiban Co., Ltd.) on it, observe the peeled surface after peeling off at a 180 degree peel angle, When the peeled area is less than 5%, ◎ is 5% or more and less than 10%, ◯ is 10% or more and less than 50%, and Δ is 50% or more.

(10) Measuring method of softening point Using a flow tester CFT-500D manufactured by Shimadzu Corporation, the temperature at which half of the non-heat resistant particles flowed out was measured as the softening point.

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 the polyester (A), the same method as the production method of the polyester (A) is used except that 0.5% by weight of silica particles having an average particle size of 0.1 μm is added to the produced polyester before melt polymerization. Thus, polyester (C) was obtained.

<Method for producing polyester (D)>
In the production method of polyester (A), the same method as the production method of polyester (A) is used except that 0.5% by weight of silica particles having an average particle diameter of 3.2 μm is added to the produced polyester before melt polymerization. Thus, polyester (D) was obtained.

Examples of compounds constituting each coating layer are as follows.
(Example compounds)
Non-heat-resistant particles: (IA) Non-heat-resistant non-crosslinked styrene / acrylic resin having an average particle size of 0.37 μm, a softening point of 220 ° C. and a glass transition point of 110 ° C., copolymerized with a composition of methyl methacrylate / styrene = 70/30 Particles / Non-heat-resistant particles: (IB) Non-heat-resistant, non-crosslinked acrylic particles having an average particle size of 0.09 μm, a softening point of 210 ° C., and a glass transition point of 60 ° C., copolymerized with a composition of methyl methacrylate / butyl acrylate = 80/20 Silica particles: (IC) Silica particles with an average particle size of 0.14 μm Silica particles: (ID) Silica particles with an average particle size of 0.30 μm

・ Polyester resin with condensed polycyclic aromatic: (IIA)
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 with condensed polycyclic aromatic structure: (IIB)
Water dispersion of polyester resin copolymerized with the following composition: Monomer composition: (acid component) 2,6-naphthalenedicarboxylic acid / terephthalic acid / 5-sodium sulfoisophthalic acid // (diol component) ethylene glycol / diethylene glycol = 78/15 / 7 // 90/10 (mol%)

・ Polyester resin: (IIIA)
Water dispersion of polyester resin copolymerized with the following composition: Monomer composition: (acid component) terephthalic acid / isophthalic acid / 5-sodium sulfoisophthalic acid // (diol component) ethylene glycol / 1,4-butanediol / diethylene glycol = 56/40/4 // 70/20/10 (mol%)

-Urethane resin: (IIIB)
Water of polyester polyurethane resin formed from isophorone diisocyanate unit: terephthalic acid unit: isophthalic acid unit: ethylene glycol unit: diethylene glycol unit: dimethylolpropanoic acid unit = 12: 19: 18: 21: 25: 5 (mol%) Dispersion.

Acrylic resin: (IIIC) 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)

・ Oxazoline compounds: (IVA)
Acrylic polymer having an oxazoline group and a polyalkylene oxide chain Epocross (Oxazoline group amount = 4.5 mmol / g, manufactured by Nippon Shokubai Co., Ltd.)

・ Isocyanate compounds: (IVB)
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.

・ Carbodiimide compounds: (IVC)
Polycarbodiimide compound Carbodilite (carbodiimide equivalent = 600, manufactured by Nisshinbo Co., Ltd.)

Epoxy compound: (IVD) polyglycerol polyglycidyl ether

Example 1:
A mixed raw material in which polyesters (A) and (B) are mixed at a ratio of 97% and 3%, respectively, is used as a raw material for the outermost layer (surface layer), and polyesters (A) and (B) are respectively at a ratio of 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 / Coextruded and cooled and solidified with a layer structure of (surface layer = 1: 18: 1 discharge amount) to obtain an unstretched film. Thereafter, an aqueous coating solution A1 shown in Table 1 below was applied to both sides of the unstretched film and dried to obtain a film having a coating layer with a coating amount (after drying) of 1.8 g / m ^{2 on} one side. 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, then led to a tenter, stretched 4.0 times at 120 ° C. in the transverse direction, and heat-treated at 230 ° C. Thereafter, the film was relaxed by 2% in the transverse direction to obtain a polyester film having a thickness of 125 μm. When the obtained polyester film was evaluated, the roughness of the film after longitudinal stretching was sufficient, transparency was good, interference unevenness characteristics, and adhesion were also good. The properties of this film are shown in Tables 2 and 3 below.

Examples 2 to 22:
A polyester film was obtained in the same manner as in Example 1 except that the coating composition was changed to the coating composition shown in Table 1 and the coating amount was changed to the amount shown in Table 2. As shown in Tables 2 and 3 below, the finished polyester film had sufficient film roughness after longitudinal stretching, good transparency, good interference unevenness characteristics, and good adhesion.

Example 23:
A mixed raw material in which polyesters (A), (B), and (C) were mixed at a ratio of 96%, 3%, and 1%, respectively, was used as a raw material for the outermost layer (surface layer), and polyesters (A) and (B) were each 97 %, 3% of the mixed raw material is used as an intermediate layer raw material, each is 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 film. Thereafter, an aqueous coating solution A3 shown in Table 1 below was applied to both sides of the unstretched film and dried to obtain a film having a coating layer with a coating amount (after drying) of 1.8 g / m ^{2 on} one side. 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, then led to a tenter, stretched 4.0 times at 120 ° C. in the transverse direction, and heat-treated at 230 ° C. Thereafter, the film was relaxed by 2% in the transverse direction to obtain a polyester film having a thickness of 125 μm. When the obtained polyester film was evaluated, the roughness of the film after longitudinal stretching was sufficient, transparency was good, interference unevenness characteristics, and adhesion were also good. The properties of this film are shown in Tables 2 and 3 below.

Example 24:
A mixed raw material in which polyesters (A) and (B) are mixed at a ratio of 97% and 3%, respectively, is used as a raw material for the outermost layer (surface layer), and polyesters (A) and (B) are respectively at a ratio of 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 / Coextruded and cooled and solidified with a layer structure of (surface layer = 1: 18: 1 discharge amount) to obtain an unstretched film. Thereafter, an aqueous coating solution B1 shown in Table 1 below was applied to both sides of the unstretched film and dried to obtain a film having a coating layer with a coating amount (after drying) of 0.2 g / m ² . Next, the film was stretched 3.4 times in the machine direction at a film temperature of 85 ° C. using the roll peripheral speed difference, and then the aqueous coating solution A3 shown in Table 1 below was applied to both surfaces of the longitudinally stretched film. Then, the film was stretched 4.0 times at 120 ° C. in the transverse direction, heat treated at 230 ° C., and then relaxed by 2% in the transverse direction. A polyester film with a thickness of 125 μm having a second coating layer of m ² was obtained. When the obtained polyester film was evaluated, the roughness of the film after longitudinal stretching was sufficient, transparency was good, interference unevenness characteristics, and adhesion were also good. The properties of this film are shown in Tables 2 and 3 below.

Comparative Example 1:
In Example 1, it manufactured like Example 1 except not providing an application layer, and obtained the polyester film. When the finished polyester film was evaluated, as shown in Table 2 below, the film after longitudinal stretching had a small roughness and was likely to be damaged.

Comparative Examples 2-4:
In Example 1, it manufactured like Example 1 except having changed a coating agent composition into the coating agent composition shown in following Table 1, and obtained the polyester film. As shown in Tables 2 and 3, the finished polyester film has a high haze and is whitish as a film, or when the roughness of the film after longitudinal stretching is insufficient, or when the interference unevenness characteristic is poor. It was observed. In Comparative Example 2, the haze was high and an accurate absolute reflectance could not be measured.

Comparative Example 5:
A mixed raw material in which polyesters (A), (B), and (D) were mixed at a ratio of 92%, 3%, and 5%, respectively, was used as a raw material for the outermost layer (surface layer), and polyesters (A) and (B) were each 97 %, 3% of the mixed raw material is used as an intermediate layer raw material, each is 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 film. Thereafter, an aqueous coating solution B3 shown in Table 1 below was applied to both sides of the unstretched film and dried to obtain a film having a coating layer with a coating amount (after drying) of 1.8 g / m ^{2 on} one side. 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, then led to a tenter, stretched 4.0 times at 120 ° C. in the transverse direction, and heat-treated at 230 ° C. Thereafter, the film was relaxed by 2% in the transverse direction to obtain a polyester film having a thickness of 125 μm. When the obtained polyester film was evaluated, a particle feeling was observed and the film was whitish. The properties of this film are shown in Tables 2 and 3 below.

  The film of the present invention, for example, has excellent transparency such as a film member for transparent electrodes such as a touch panel, a film for molding, etc., needs to reduce interference unevenness due to adhesion with various surface functional layers and external light reflection. It can be suitably used for a certain application.

Claims (1)

A laminated polyester film comprising a coating layer formed from a coating solution containing a compound having non-heat resistant particles and a condensed polycyclic aromatic compound on at least one side of the polyester film.