JP2015178259A - Laminate polyester film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyester film in which haze is greatly lowered by forming various functional layers such as a hard coat layer, and which can be suitably used in applications where it is desired to easily distinguish between a film with a functional layer processed and a film with a functional layer unprocessed, for example, the polyester film capable of being suitably used as a transparent electrode of a touch panel or the like and a member for a film for molding.SOLUTION: There is provided a laminate polyester film which has a coating layer formed by stretching on at least one surface of a polyester film in at least one direction and in which the content of particles having an average particle diameter of 0.10 to 1.0 μm in the coating layer is over 10 wt.%.

Description

  The present invention relates to a laminated polyester film, for example, in an application for forming a functional layer such as a backlight unit of a liquid crystal display, a hard coat layer, a sticking prevention layer, a light diffusion layer, a prism layer, a microlens layer, The present invention relates to a laminated polyester film suitable for easily distinguishing between processing and unprocessed functional layers.

  In recent years, a polyester film has been used for various applications such as each member of a liquid crystal display, such as a hard coat film, a light diffusion sheet, a prism sheet, a microlens sheet, an antireflection film, and an electromagnetic wave shielding film. The base film used for these members is required to have excellent transparency and visibility.

  Therefore, the film used for these uses generally has high transparency. However, because of its high transparency, it is not easy to distinguish between processed films with various functional layers and unprocessed films before processing. There was a possibility of mistaken goods and raw products.

  Polyester film is generally used as a transparent base film for forming various functional layers such as hard coat layer, anti-sticking layer, light diffusion layer, prism layer and microlens layer, considering transparency and mechanical properties. In order to improve the adhesion between the polyester film of the base material and various functional layers, an easily adhesive coating layer is generally provided as an intermediate layer.

JP 2007-55222 A

  The present invention has been made in view of the above circumstances, and the problem to be solved is, for example, in an application for forming a functional layer such as a hard coat layer, a sticking prevention layer, a light diffusion layer, a prism layer, or a microlens layer. An object of the present invention is to provide an excellent laminated polyester film in order to easily distinguish between functional and processed layers.

  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 that at least one surface of a polyester film has a coating layer formed by stretching in at least one direction, and the average particle size in the coating layer is 0.10 to 1.0 μm. It exists in the laminated polyester film characterized by content of particle | grains exceeding 10 weight%.

  According to the laminated polyester film of the present invention, by forming various functional layers such as a hard coat layer, an anti-sticking layer, a light diffusion layer, a prism layer, a microlens layer, the haze is greatly reduced, The base film which can make a raw distinction easy to be provided 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.

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

  There is no restriction | limiting in particular as a polymerization catalyst of polyester, A conventionally well-known compound can be used, For example, an antimony compound, a titanium compound, a germanium compound, a manganese compound, an aluminum compound, a magnesium compound, a calcium compound etc. are mentioned. Among these, titanium compounds and germanium compounds are preferable because they have high catalytic activity, can be polymerized in a small amount, and the amount of metal remaining in the film is small, so that the brightness of the film becomes high. Furthermore, since a germanium compound is expensive, it is more preferable to use a titanium compound.

  In the case of polyester using a titanium compound, the titanium element content is preferably 50 ppm or less, more preferably 1 to 20 ppm, and still more preferably 2 to 10 ppm. If the content of the titanium compound is too high, the polyester may be deteriorated in the process of melt-extruding the polyester, resulting in a strong yellowish film. If the content is too low, the polymerization efficiency is poor and the cost is low. In some cases, a film having a sufficient strength or a sufficient strength cannot be obtained. Moreover, when using the polyester by a titanium compound, it is preferable to use a phosphorus compound in order to reduce the activity of a titanium compound for the purpose of suppressing deterioration in the step of melt extrusion. As the phosphorus compound, orthophosphoric acid is preferable in view of the productivity and thermal stability of the polyester. The phosphorus element content is preferably in the range of 1 to 300 ppm, more preferably 3 to 200 ppm, and still more preferably 5 to 100 ppm with respect to the amount of polyester to be melt-extruded. If the content of the phosphorus compound is too large, it may cause gelation or foreign matter. If the content is too small, the activity of the titanium compound cannot be lowered sufficiently, and the yellowish It may be a 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.

  Examples of the ultraviolet absorber include an organic ultraviolet absorber and an inorganic ultraviolet absorber, and 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. 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, zirconium 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. Of these, silica particles are preferred because they are particularly effective in a small amount.

  The average particle diameter of the particles is preferably 5 μm or less, more preferably 0.01 to 3 μm. By using the average particle diameter within the above range, an appropriate surface roughness is imparted to the film, and in the case where various functional layers and the like are formed in a subsequent process, problems are unlikely to occur.

Furthermore, the particle content in the polyester layer is preferably less than 5% by weight, more 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.
Moreover, when there is too much particle content, even if a functional layer is formed, haze will not fully fall, and transparency of a film may be inadequate.

The shape of the particles to be used is not particularly limited, and any of a spherical shape, a block shape, a rod shape, a flat shape, and the like may be used. Moreover, there is no restriction | limiting in particular also about the hardness, specific gravity, a color, etc.
These series of particles may be used in combination of two or more as required.

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

  In addition to the above-mentioned particles, conventionally known antioxidants, antistatic agents, thermal stabilizers, lubricants, dyes, pigments, and the like can be added to the polyester film in the present invention as necessary.

  The thickness of the polyester film in the present invention is not particularly limited as long as it can be formed as a film, but it is preferably 10 to 350 μm, more preferably 20 to 300 μm.

  As a film forming method of the film of the present invention, a generally known film forming method can be adopted, and there is no particular limitation. For example, when producing a biaxially stretched polyester film, the polyester raw material described above is first melt-extruded from a die using an extruder, and the molten sheet is cooled and solidified with a cooling roll to obtain an unstretched sheet. In this case, in order to improve the flatness of the sheet, it is preferable to improve the adhesion between the sheet and the rotary cooling drum, and an electrostatic application adhesion method or a liquid application adhesion method is preferably employed. Next, the obtained 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-stage stretching direction at usually 70 to 170 ° C. and the stretching ratio is usually 2.5 to 7 times, preferably 3.0 to 6 times. Subsequently, a method of obtaining a biaxially oriented film by performing heat treatment at a temperature of 180 to 270 ° C. under tension or under relaxation within 30% can be mentioned. 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. The coating layer of the present invention is formed by stretching in at least one direction, and is preferably provided by in-line coating that treats the film surface during the process of forming a polyester film.

  In-line coating is a method of coating within the process of manufacturing a polyester film, and specifically, a method of coating at any stage from melt extrusion of a polyester to heat setting after stretching and winding up. Usually, coating is performed on either an unstretched sheet obtained by melting and rapid cooling, or a stretched uniaxially stretched film. Although not limited to the following, for example, in sequential biaxial stretching, a method of stretching in the transverse direction after coating a uniaxially stretched film stretched in the longitudinal direction (longitudinal direction) is particularly excellent. According to such a method, film formation and coating layer formation can be performed at the same time, so there is an advantage in manufacturing cost. In addition, in order to perform stretching after coating, the thickness of the coating layer can be changed by the stretching ratio. Compared to offline coating, thin film coating can be performed more easily. Further, by providing the coating layer on the film before stretching, the coating layer can be stretched together with the base film, whereby the coating layer can be firmly adhered to the base film. Furthermore, in the production of a biaxially stretched polyester film, the film can be restrained in the longitudinal and lateral directions by stretching while gripping the film end with a clip, etc. High temperature can be applied while maintaining the properties. Therefore, since the heat treatment performed after coating can be performed at a high temperature that cannot be achieved by other methods, the film forming property of the coating layer can be improved, and the coating layer and the base film can be more firmly adhered to each other. Furthermore, it can be set as a firm coating layer, and performances such as adhesion to various functional layers that can be formed on the coating layer and wet heat resistance can be improved.

  In the present invention, it is an essential requirement to have a coating layer containing more than 10% by weight of particles having an average particle diameter of 0.10 to 1.0 μm.

  The film of the present invention makes it easy to distinguish between processed and unprocessed functional layers by reducing the haze after forming functional layers such as hard coat layers, anti-sticking layers, light diffusing layers, prism layers, and microlens layers. It is a design to do.

  The coating layer is designed to increase haze by adding more than 10% by weight of particles having an average particle size of 0.10 to 1.0 μm in the coating layer, thereby imparting unevenness of the particles to the coating layer. By forming a functional layer on the coating layer, the functional layer fills the irregularities caused by the particles to eliminate surface irregularities and reduce haze, so that it becomes transparent, and the functional layer is distinguished from processed and unprocessed. It makes things easier.

  As the particles to be contained in the coating layer, various conventionally known particles can be used. For example, silica, calcium carbonate, magnesium carbonate, barium carbonate, calcium sulfate, calcium phosphate, magnesium phosphate, kaolin, aluminum oxide, Examples include inorganic particles such as zirconium oxide and titanium oxide, and organic particles such as acrylic resin, styrene resin, urea resin, phenol resin, epoxy resin, and benzoguanamine resin. Among them, inorganic particles are preferable in that hardness can be imparted, and silica particles are more preferable in consideration of stability in the state of the coating liquid. In addition, a metal oxide is also preferable in that it has a large refractive index difference from the polymer used to hold the particles in the coating layer, thereby increasing light scattering and increasing haze.

  It is essential that the average particle size of the particles used in the coating layer is 0.10 to 1.0 μm, preferably 0.10 to 0.70 μm, more preferably 0.20 to 0.60 μm, still more preferably. It is in the range of 0.25 to 0.50 μm. By using in these ranges, the haze of the coating layer can be made sufficiently high, and it becomes easy to distinguish between processing and non-processing of the functional layer. In addition, there is an advantage that it is possible to prevent the particles from falling off the coating layer.

  In the present invention, it is preferable to contain a polymer in the coating layer. The role of the polymer includes holding the above-described particles in the coating layer and improving adhesion with various functional layers that can be formed on the coating layer.

  A conventionally well-known polymer can be used as a polymer. Specific examples of the polymer include acrylic resin, polyester resin, urethane resin, polyvinyl (polyvinyl alcohol, vinyl chloride vinyl acetate copolymer, etc.), polyalkylene glycol, polyalkyleneimine, methylcellulose, hydroxycellulose, starches and the like. . Among these, it is preferable to use an acrylic resin, a polyester resin, or a urethane resin from the viewpoint of improving adhesion with various functional layers and improving the appearance of coating. In view of compatibility with the polyester film of the base material, a polyester resin is more preferable, and from the viewpoint that adhesion with a functional layer such as a hard coat layer or a prism layer is further improved, an acrylic resin or a urethane resin is used. It is preferable. An acrylic resin is most preferable from the viewpoint that even if the haze is high, the light transmittance can be increased and defect inspection by various defect inspection machines can be facilitated.

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

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

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

  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.) and those having derivative units of lactone compounds such as polycaprolactone.

  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.

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

  Examples of the polyisocyanate compound used for obtaining the urethane resin include aromatic diisocyanates such as tolylene diisocyanate, xylylene diisocyanate, methylene diphenyl diisocyanate, phenylene diisocyanate, naphthalene diisocyanate, and tolidine diisocyanate, α, α, α ′, α ′. -Aliphatic diisocyanates having aromatic rings such as tetramethylxylylene diisocyanate, aliphatic diisocyanates such as methylene diisocyanate, propylene diisocyanate, trimethylhexamethylene diisocyanate, hexamethylene diisocyanate, cyclohexane diisocyanate, methylcyclohexane diisocyanate, isophorone diisocyanate, dicyclohexyl Methanzi Cyanate, alicyclic diisocyanates such as isopropylidene dicyclohexyl diisocyanates. These may be used alone or in combination.

  A chain extender may be used when synthesizing the urethane resin, and the chain extender is not particularly limited as long as it has two or more active groups that react with an isocyanate group. Alternatively, a chain extender having two amino groups can be mainly used.

  Examples of the chain extender having two hydroxyl groups include aliphatic glycols such as ethylene glycol, propylene glycol and butanediol, aromatic glycols such as xylylene glycol and bishydroxyethoxybenzene, and esters such as neopentyl glycol hydroxypivalate. And glycols such as glycols. Examples of the chain extender having two amino groups include aromatic diamines such as tolylenediamine, xylylenediamine, and diphenylmethanediamine, ethylenediamine, propylenediamine, hexanediamine, 2,2-dimethyl-1,3- Propanediamine, 2-methyl-1,5-pentanediamine, trimethylhexanediamine, 2-butyl-2-ethyl-1,5-pentanediamine, 1,8-octanediamine, 1,9-nonanediamine, 1,10- Aliphatic diamines such as decane diamine, 1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane, dicyclohexylmethanediamine, isoprobilitincyclohexyl-4,4′-diamine, 1,4-diaminocyclohexane, 1 , 3-Bisaminomethylcyclohexa And alicyclic diamines such as

  The urethane resin in the present invention may use a solvent as a medium, but preferably uses water as a medium. In order to disperse or dissolve the urethane resin in water, there are a forced emulsification type using an emulsifier, a self-emulsification type in which a hydrophilic group is introduced into the urethane resin, and a water-soluble type. In particular, a self-emulsification type in which an ionic group is introduced into the structure of a urethane resin to form an ionomer is preferable because of excellent storage stability of the liquid and water resistance, transparency, and adhesion of the resulting coating layer.

Examples of the ionic group to be introduced include various groups such as a carboxyl group, sulfonic acid, phosphoric acid, phosphonic acid, quaternary ammonium salt, and the like, and a carboxyl group is preferable. As a method for introducing a carboxyl group into a urethane resin, various methods can be taken in each stage of the polymerization reaction. For example, there are a method of using a carboxyl group-containing resin as a copolymer component during prepolymer synthesis, and a method of using a component having a carboxyl group as one component such as polyol, polyisocyanate, and chain extender. In particular, a method in which a desired amount of carboxyl groups is introduced using a carboxyl group-containing diol depending on the amount of this component charged is preferred.
For example, dimethylolpropionic acid, dimethylolbutanoic acid, bis- (2-hydroxyethyl) propionic acid, bis- (2-hydroxyethyl) butanoic acid and the like are copolymerized with a diol used for polymerization of a urethane resin. Can do. The carboxyl group is preferably in the form of a salt neutralized with ammonia, amine, alkali metal, inorganic alkali or the like. Particularly preferred are ammonia, trimethylamine and triethylamine. In such a urethane resin, the 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.

  In addition, to form the coating layer, the coating layer of the coating layer is strengthened, and sufficient adhesion to the functional layers such as the hard coat layer, anti-sticking layer, light diffusion layer, prism layer, and microlens layer, and moisture and heat resistance are improved. Therefore, it is preferable to use a crosslinking agent in combination.

  A conventionally well-known material can be used with a crosslinking agent, For example, an oxazoline compound, an epoxy compound, an isocyanate type compound, a carbodiimide type compound, a melamine compound, a silane coupling compound etc. are mentioned. In order to further improve the adhesion with the functional layer, it is preferable to use two or more kinds of crosslinking agents in combination. Among the above, in terms of good adhesion, oxazoline compounds, epoxy compounds, isocyanate compounds, and carbodiimide compounds are more preferable, especially oxazoline compounds and epoxy compounds, oxazoline compounds and isocyanate compounds, oxazoline compounds and carbodiimide compounds, It has been found that the adhesion is markedly improved when used in combination with an isocyanate compound and a carbodiimide compound. In addition, in terms of increasing the strength of the coating layer, it has also been found that it is more preferable to use a melamine compound in combination, especially when the average particle size exceeds 0.2 μm and the particle content exceeds 10% by weight. Proved to be very effective.

  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 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 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. Among these, an active methylene compound is preferable from the viewpoint that adhesion with the functional layer is easily improved.

  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 to improve adhesion with various surface functional layers that can be formed on a coating layer and to improve the heat and humidity resistance of the coating layer. is there. 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 functional layers is improved.

  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.

  Further, in the range not impairing the gist of the present invention, an antifoaming agent, a coating property improver, a thickener, an organic lubricant, an antistatic agent, an ultraviolet absorber, and an antioxidant are formed as necessary for forming the coating layer. It is also possible to use a foaming agent, a dye, a pigment and the like in combination.

  As a ratio in the coating layer which the laminated polyester film in the present invention constitutes, the particles are in a range exceeding 10% by weight, preferably 15 to 50% by weight, more preferably 20 to 40% by weight. By using in the above range, it is possible to effectively adjust the haze.

  As a ratio in the coating layer which comprises the laminated polyester film in this invention, a polymer becomes like this. Preferably it is 15 to 80 weight%, More preferably, it is the range of 30 to 70 weight%. By using it in the above range, it is effective for good adhesion and prevention of falling off of particles.

  As a ratio in the coating layer which comprises the laminated polyester film in this invention, the component derived from a crosslinking agent becomes like this. Preferably it is the range of 5-70 weight%, More preferably, it is the range of 10-50 weight%. By using in the said range, it becomes a favorable application | coating external appearance and a firm coating layer. In particular, when it is desired to strengthen the coating layer, it is preferable to use a melamine compound in combination, and a preferable range thereof is 3 to 30% by weight, and more preferably 5 to 20% by weight.

  In the polyester film of the present invention, it is also possible to provide a coating layer on the side of the polyester film opposite to the above-described coating layer. As a constituent component of the coating layer, the above-described polymers and cross-linking agents can be used. The same coating layer may be used on both surfaces, or different coating layers may be used. For example, when different functional layers are provided on both surfaces, when the adhesiveness differs between the functional layers, different coating layers can be used depending on the application.

  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.

  Regarding the formation of the coating layer, the above-described series of compounds is used as a solution or solvent dispersion, and the coating solution adjusted with a solid content concentration of about 0.1 to 80% by weight as a guide is laminated on the polyester film. It is preferred to produce a polyester film. In particular, when the coating layer is provided by in-line coating, an aqueous solution or a water dispersion is more preferable, but a small amount of an organic solvent is added to the coating solution for the purpose of improving the dispersibility in water and improving the film forming property. You may contain. Moreover, only one type of organic solvent may be used, and two or more types may be used as appropriate.

  Regarding the laminated polyester film in the present invention, the thickness of the coating layer provided on the polyester film is usually in the range of 0.001 to 1 μm, preferably 0.01 to 0.5 μm, more preferably 0.02 to 0.2 μm. It is. By making the film thickness within the above range, the appearance of the coating layer, the adhesion with the functional layer, and the prevention of falling off of the particles can be improved. In addition, from the viewpoint that defect inspection by various defect inspection machines can be facilitated, the film thickness is preferably 0.07 to 0.20 μm, more preferably 0 in order to increase the light transmittance. It is good to set it as the range of 0.08-0.15 micrometer.

  In the case of the method of forming surface irregularities on the coating layer using particles, the relationship between the average particle diameter of the particles and the film thickness of the coating layer is preferably 1.0 as the average particle diameter / film thickness of the coating layer. The above range, more preferably in the range of 1.2 to 20, more preferably in the range of 1.5 to 15, particularly preferably in the range of 1.7 to 10. By using in the said range, it can increase in haze as a laminated polyester film provided with the coating layer, and haze reduction after providing a functional layer can be performed effectively. In addition, it is possible to contribute to preventing the particles from falling off the coating layer.

  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.

  In the present invention, the drying and curing conditions for forming the coating layer on the polyester film are not particularly limited. For example, the heat treatment is usually performed at 70 to 270 ° C. for 3 to 200 seconds. good.

  Moreover, you may use together heat processing and active energy ray irradiation, such as ultraviolet irradiation, as needed. 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 amount of haze reduction by forming a functional layer on the coated layer of the polyester film of the present invention is preferably 1.0% or more, more preferably 3.0% or more, still more preferably 5.0% or more, particularly preferably. Is in the range of 8.0% or more, most preferably 10% or more. By setting the above range, it becomes easy to distinguish between processing / unprocessed functional layers according to various places such as a conference room, a work room, an inspection room, and a film view. Various studies have revealed that, within the scope of the present invention, even if the haze value is the same, the smaller the average particle size of the particles, the more apparent haze value becomes whitish, and the functional layer is processed / unprocessed. It was found that it was easier to distinguish.

  The haze of the polyester film of the present invention is preferably in the range of 3.0% or more, more preferably 5.0% or more, further preferably 10% or more, and particularly preferably 12% or more. By setting the haze in the above range, it is possible to make it easier to distinguish whether the functional layer is processed or not processed.

  In general, a functional layer is formed on the coating layer of the laminated polyester film of the present invention. As the functional layer, for example, a hard coat layer, an anti-sticking layer, a light diffusion layer, a prism layer, a microlens layer, an ink layer, a pressure-sensitive adhesive layer, an adhesive layer, and the like are provided for imparting various functions. That is. Among these functional layers, the present invention is particularly suitable for forming a hard coat layer, an anti-sticking layer, a light diffusion layer, a prism layer, and a microlens layer. The functional layer is not particularly limited as long as the haze is lowered when formed on the coating layer, but usually the haze is preferably not so high, and the haze of only the functional layer is preferably 8.0% or less, More preferably, it is 3.0% or less, More preferably, it is 1.0% or less of range. Similarly, the thickness of the functional layer is not particularly limited as long as the haze is lowered when formed on the coating layer, but is preferably 0.1 to 500 μm, more preferably 1 to 100 μm, and still more preferably 1 to 1 μm. The range is 50 μm.

  As an example of the functional layer, for example, in the case of a hard coat layer, the material to be used is not particularly limited. For example, reactive silicon compounds such as monofunctional (meth) acrylate, polyfunctional (meth) acrylate, and tetraethoxysilane And the like. 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 aromatic (meth) acrylates such as coxyalkyl (meth) acrylate, benzyl (meth) acrylate, 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 a 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 anti-sticking layer and the light diffusing layer contain particles and a binder. The anti-sticking layer contains the same binder and particles as the light diffusion layer, and the content of the particles is not intended to be light diffusive. Therefore, a method of containing a smaller amount with a smaller particle size is generally used. It is.

  As particles to be included in the anti-sticking layer and the light diffusion layer, conventionally known particles can be used. Organic particles such as acrylic resin, acrylic urethane resin, urethane resin, polyester resin, and polyvinyl resin, silica, metal oxide And inorganic particles such as barium sulfate can be used. Of these, acrylic resins and acrylic urethane resins having good transparency are preferably used. The particle size of these particles is not particularly limited, but is 1 to 50 μm, more preferably 1 to 10 μm as an average particle size.

  The binder contained in the anti-sticking layer or the light diffusion layer is used to fix the particles. For example, polyester resin, acrylic resin, polyurethane resin, fluororesin, silicone resin, epoxy resin, the hard coat layer described above Active energy ray-curable resins used for the formation of. In consideration of processability, a polyol compound is preferably used, and examples thereof include acrylic polyol and polyester polyol.

  When a polyol compound is used as a binder, it is preferable to contain isocyanate as a curing agent. By containing isocyanate, a stronger crosslinked structure can be formed, and the physical properties as a functional layer are improved. Further, when an active energy ray curable resin is used as a binder, an acrylate resin is preferable, which can be used for improving the hardness of the functional layer.

  The mixing ratio of the binder and the particles in the anti-sticking layer and the light diffusion layer can be appropriately set depending on the characteristics to be obtained, and is not particularly limited. For example, the binder / particles are 0.1 to 50 by weight ratio. The range is more preferably 0.5 to 20.

  Analysis of the components of the functional layer can be performed by analysis such as TOF-SIMS, ESCA, fluorescent X-ray, and NMR.

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

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

(2) Measuring method of 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). The film thickness was measured at a location not including the particle portion.

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

(5) Method of measuring haze reduction when forming functional layer As functional layer, 80 parts by weight of dipentaerythritol hexaacrylate, 20 parts by weight of 2-hydroxy-3-phenoxypropyl acrylate, photopolymerization initiator (trade name) : Irgacure 184, manufactured by Ciba Specialty Chemicals Co., Ltd.) 5 parts by weight and 200 parts by weight of methyl ethyl ketone are applied onto the coating layer so that the dry film thickness is 2 μm, and cured by irradiating with ultraviolet rays to hard coat. A film in which a layer (the haze of the layer is 0.1%) was obtained. The haze was measured by the method according to (4), and the difference from the haze of the laminated polyester film before forming the functional layer was calculated.

(6) Discrimination evaluation method before and after functional layer processing The difference between the 20 cm × 20 cm film before and after the functional layer was formed on the coating layer of (5) was observed. As a method of observation, assuming a conference room, work room, and inspection room, a film and a functional layer on which a functional layer is not formed are formed on a white desk, a green cutter mat, and a black desk, respectively. The difference was observed when the film was placed and observed from directly above and from a location 1 m away at an angle of 30 degrees. 5 points if the difference can be discriminated instantaneously, 4 points if it can be easily discriminated by observation for 3 seconds, 3 points if it can be discriminated if you look carefully, 2 points if it is difficult to discriminate, 1 point if it cannot be discriminated did. A higher score is preferable, and it is ideal that there are three or more points when observed from right above or obliquely under any of the three conditions.

(7) Method for evaluating adhesion of coating layer The film in which the functional layer is formed on the coating layer of (5) is treated at 80 ° C. and 90% RH for 50 hours, and then 10 × 10 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.

(8) Evaluation method of strength of coating layer (strength 1)
The surface of the coating layer was rubbed three times with a finger pad wrapped with ERIEL (registered trademark) Pro Wipe Soft Micro Wiper S220 manufactured by Daio Paper Co., Ltd., and the surface was observed. The case where the scraped area of the coating layer was less than 10% was evaluated as ◯, the case where it was 10% or more and less than 50% was evaluated as Δ, and the case where it was 50% or more was evaluated as ×.

(9) Evaluation method of strength of coating layer (strength 2)
The surface of the coating layer was rubbed with the belly of the finger, and the case where peeling of the coating layer was not observed was marked with ◯, and the case where peeling of the coating layer was seen was marked with x. The evaluation is weaker than the strength (1) of (8). When peeling is observed in this evaluation, the strength is too weak and is not suitable for processing the functional layer.

The polyester used in the examples and comparative examples was prepared as follows.
<Method for producing polyester (A)>
100 parts by weight of dimethyl terephthalate, 60 parts by weight of ethylene glycol, 30 ppm of ethyl acid phosphate with respect to the resulting polyester, and 100 ppm of magnesium acetate tetrahydrate with respect to the resulting polyester as the catalyst at 260 ° C. in a nitrogen atmosphere at 260 ° C. The reaction was allowed to proceed. Subsequently, 50 ppm of tetrabutyl titanate was added to the produced polyester, the temperature was raised to 280 ° C. over 2 hours and 30 minutes, the pressure was reduced to 0.3 kPa in absolute pressure, and melt polycondensation was further performed for 80 minutes to obtain the intrinsic viscosity. 0.63 polyester (A) was obtained.

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

<Method for producing polyester (C)>
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)
・ Particles: (IA) Silica particles with an average particle size of 0.20 μm ・ Particles: (IB) Silica particles with an average particle size of 0.30 μm ・ Particles: (IC) Silica particles with an average particle size of 0.45 μm

Acrylic resin: (IIA) 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)

・ Polyester resin: (IIB)
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: (IIC)
Water of polyester urethane 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.

・ Oxazoline compounds: (IIIA)
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.)

Epoxy compound: (IIIB) polyglycerol polyglycidyl ether

・ Isocyanate compounds: (IIIC)
1000 parts of hexamethylene diisocyanate was stirred at 60 ° C., and 0.1 part of tetramethylammonium capryate was added as a catalyst. After 4 hours, 0.2 part of phosphoric acid was added to stop the reaction, and an isocyanurate type polyisocyanate composition was obtained. 100 parts of the obtained isocyanurate type polyisocyanate composition, 42.3 parts of methoxypolyethylene glycol having a number average molecular weight of 400, and 29.5 parts of propylene glycol monomethyl ether acetate were charged and maintained at 80 ° C. for 7 hours. Thereafter, the reaction solution temperature was kept at 60 ° C., 35.8 parts of methyl isobutanoyl acetate, 32.2 parts of diethyl malonate, and 0.88 part of 28% methanol solution of sodium methoxide were added and kept for 4 hours. Block polyisocyanate obtained by adding 58.9 parts of n-butanol, maintaining the reaction solution temperature at 80 ° C. for 2 hours, and then adding 0.86 part of 2-ethylhexyl acid phosphate.

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

Melamine compound: (IIIE) hexamethoxymethylol melamine

Example 1:
A mixed raw material in which polyesters (A), (B), and (C) were mixed in proportions of 91%, 3%, and 6%, 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 sheet.
Next, the film was stretched 3.4 times in the longitudinal direction at a film temperature of 85 ° C. using the difference in roll peripheral speed, and then the coating liquid 1 shown in Table 1 below was applied to one side of the longitudinally stretched film with the film thickness (dried) After coating to 0.11 μm, led to a tenter, stretched 4.0 times at 120 ° C. in the transverse direction, heat treated at 225 ° C., relaxed 2% in the transverse direction, and 125 μm thick A polyester film was obtained.

  When the obtained polyester film was evaluated, the haze was 9.0%, the haze reduction amount was 8.4%, and the discrimination between the film without the functional layer and the film with the functional layer was good. Met. Moreover, the adhesiveness with a functional layer and the intensity | strength of the application layer were also favorable. The properties of this film are shown in Table 2 below.

Examples 2 to 19:
In Example 1, it manufactured similarly to Example 1 except having changed the coating agent composition into the coating agent composition shown in Table 1, and obtained the polyester film. As shown in Table 2, the finished polyester film had good discrimination between the film in which the functional layer was not formed and the film in which the functional layer was formed.

Comparative Example 1:
In Example 1, it manufactured similarly to Example 1 except having not provided the application layer, and obtained the polyester film. When the completed polyester film was evaluated, as shown in Table 2 below, it was a result of poor discriminability between a film in which a functional layer was not formed and a film in which a functional layer was formed, and the adhesion was also poor.

Comparative Examples 2 and 3:
In Example 1, it manufactured similarly to Example 1 except having changed the coating agent composition into the coating agent composition shown in Table 1, and obtained the polyester film. When the completed polyester film was evaluated, as shown in Table 2 below, the discriminability between the film in which the functional layer was not formed and the film in which the functional layer was formed was not sufficient.

Comparative Example 4:
On one side of the film obtained in Comparative Example 1, the coating solution A2 shown in Table 1 below was applied so that the thickness of the coating layer (after drying) was 0.11 μm, and dried at 100 ° C. A laminated polyester film was obtained. When the finished polyester film was evaluated, the strength was weaker than that of a coating layer formed by stretching, and it was not suitable for forming a functional layer.

  The film of the present invention can be used to form a functional layer such as a backlight unit of a liquid crystal display, a hard coat layer, an anti-sticking layer, a light diffusion layer, a prism layer, a microlens layer, etc. It can be suitably used for applications where it is desired to easily distinguish between processes.

That is, the gist of the present invention is that at least one surface of a polyester film has a coating layer formed by stretching in at least one direction, and the average particle size in the coating layer is 0.10 to 1.0 μm. It exists in the laminated polyester film characterized by the content of particle | grains exceeding 10 weight%, and the haze of a film being 3.0% or more .

Claims (1)

It has a coating layer formed by stretching in at least one direction on at least one surface of the polyester film, and the content of particles having an average particle size of 0.10 to 1.0 μm in the coating layer is 10% by weight. The laminated polyester film characterized by exceeding.