JP6440655B2 - Laminated polyester film - Google Patents

Description

  The present invention relates to a laminated polyester film. For example, in a use for forming a functional layer such as a prism layer or a microlens layer, such as a backlight unit of a liquid crystal display, it is easy to distinguish between processed and unprocessed functional layers. Therefore, the present invention relates to a laminated polyester film suitable for the purpose.

  In recent years, polyester films have been used in various applications such as liquid crystal display members such as prism sheets, microlens sheets, hard coat films, antireflection films, light diffusion sheets, and electromagnetic wave shielding films. 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.

  For example, the prism sheet is for improving the optical efficiency of the backlight and improving the luminance. As the transparent base film, a polyester film is generally used in consideration of transparency and mechanical properties. In order to improve the adhesion between the base polyester film and the prism layer, these intermediate layers are easily bonded. In general, a conductive coating layer is provided (Patent Document 1).

  As a method for forming the prism layer, for example, an active energy ray-curable coating material is introduced into a prism type, irradiated with active energy rays while being sandwiched between polyester films, the resin is cured, and the prism type is removed to remove polyester. The method of forming on a film is mentioned. In the case of such a method, it is necessary to use a solventless active energy ray-curable resin in order to form the prism type with precision. However, the solvent-free resin has a problem that the penetration and swelling effects on the easy-adhesion layer laminated on the polyester film are low and the adhesion tends to be insufficient as compared with the solvent-based resin.

JP 2000-229395 A

  The present invention has been made in view of the above circumstances, and the problem to be solved is, for example, a functional layer such as a solventless active energy ray-curable resin layer used for forming a prism layer, a microlens layer, or the like. It is an object of the present invention to provide an excellent laminated polyester film in order to make it easy to distinguish between processing and unprocessed functional 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 a polyester film having on at least one surface a coating layer containing a urethane resin, at the time of forming a functional layer on the coating layer, reduced haze 1.0% or more, the In the laminated polyester film, the functional layer is a layer selected from a prism layer, a microlens layer, a hard coat layer, a light diffusion layer, an ink layer, an adhesive layer, and an adhesive layer.

  According to the laminated polyester film of the present invention, by forming various functional layers such as a solvent-free active energy ray-curable resin layer used for forming a prism layer, a microlens layer, etc., the haze is greatly reduced. In addition, it is possible to provide a base film that can easily distinguish between processing and non-processing of the functional layer, 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, 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 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.

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

  In the polyester layer of the film of the present invention, particles can be blended mainly for the purpose of imparting slipperiness and preventing scratches in each step. 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 usually 5 μm or less, preferably 0.01 to 3 μm. When the average particle diameter exceeds 5 μm, the surface roughness of the film becomes too rough, and a problem may occur when various functional layers are formed in a subsequent process.

  Further, the content of particles in the polyester layer is usually less than 5% by weight, preferably in the range of 0.0003 to 3% by weight. When there are no or few particles, the transparency of the film becomes high and the film becomes a good film, but the slipperiness may be insufficient. There are cases where improvement is required. In addition, when the particle content exceeds 5% by weight, the haze is not sufficiently lowered even when the functional layer is formed, and the transparency of the film may be insufficient.

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

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

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

  Although the thickness of the polyester film in this invention will not be specifically limited if it can be formed into a film as a film, Usually, 10-350 micrometers, Preferably it is the range of 20-300 micrometers.

  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. Regarding the coating layer, it may be provided by in-line coating which treats the film surface during the process of forming a polyester film, or offline coating which is applied outside the system on a once produced film may be adopted. More preferably, it is formed by in-line coating.

  In-line coating is a method of coating within the process of manufacturing a polyester film, and specifically, a method of coating at any stage from melt extrusion of a polyester to heat setting after stretching and winding up. Usually, it is coated on any of an unstretched sheet obtained by melting and quenching, a stretched uniaxially stretched film, a biaxially stretched film before heat setting, and a film after heat setting and before winding. 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 this invention, it has an application layer containing a urethane resin, and when forming a functional layer on the said application layer, it is an essential requirement that haze falls by 1.0% or more.

  The film of the present invention can be used to form a prism layer, a microlens layer, and the like. The functional layer such as a solventless active energy ray-curable resin layer is formed, and the haze is lowered after the functional layer is formed. This design makes it easy to distinguish between processes.

  In order to reduce the haze by 1.0% or more when the functional layer is formed on the coating layer, it is preferable to set the haze of the laminated polyester film having the coating layer before forming the functional layer high. It is possible to adjust both from the haze of the polyester film of the substrate and the haze of the coating layer. In order to increase the haze, for example, there is a method in which particles are contained in a substrate or a coating layer to diffuse light. Since it depends on the refractive index of the particles, it cannot be generally stated, but in general, the larger the particle size and the larger the amount, the higher the haze tends to be. Therefore, it is possible to adjust the haze by changing the particle size or amount according to the purpose.

  In order to reduce haze when a functional layer is formed on the coating layer, a technique of reducing the surface irregularities formed by the polyester film or coating layer of the substrate by forming the functional layer is effective. . Surface irregularities can be formed from both the design of the polyester film of the substrate and the design of the coating layer, as in the adjustment of the film haze. When adjusting with the design of the polyester film of the base material, for example, a method of incorporating particles in the outermost polyester film layer on the coating layer side (side on which the functional layer is formed) rather than the intermediate layer of the polyester film in a multilayer configuration However, it is preferable because surface irregularities are easily formed. In addition, the method of forming the surface irregularities mainly by adjusting the design of the coating layer that is in direct contact with the functional layer, that is, the outermost layer of the laminated polyester film of the present invention, by adjusting the design of the base material formed the functional layer. It is more preferable because the haze reduction at that time becomes efficient.

  Examples of the method for forming the surface unevenness in which the haze is lowered by the functional layer include a method of containing particles and a method of forming unevenness on the coating layer itself. As a method for forming irregularities on the coating layer itself, a method of forming a coating layer by mixing and mixing polymers having poor stability, or a film stretching process by coating a polymer having poor stretching followability The method of forming a coating layer through this is mentioned. Considering the stability of the haze value due to production, the liquid stability of the coating solution, etc., a method of incorporating particles in the coating layer is preferable. In particular, the method of incorporating particles in the coating layer is preferable because blocking and slipperiness can be improved. In addition, an increase in the surface area of the coating layer has an effect of contributing to an improvement in adhesion to the functional layer.

  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.

  The average particle size of the particles used in the coating layer cannot be generally described because it depends on the thickness of the coating layer, but is generally 0.01 to 1.0 μm, preferably 0.05 to 0.8 μm. More preferably, it is 0.1-0.7 micrometer, Most preferably, it is the range of 0.2-0.5 micrometer.

  In the present invention, the coating layer contains a urethane resin. The role of the urethane resin includes holding the above-described particles in the coating layer and improving the adhesion with various functional layers that can be formed on the coating layer.

  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.

  Moreover, it is preferable to introduce | transduce a carbon-carbon double bond in a urethane resin in order to improve adhesiveness. The coating layer contains a carbon-carbon double bond, and the carbon-carbon double compound is a compound used for forming the double bond and a solvent-free active energy ray-curable resin layer such as a prism layer or a microlens layer. It is possible to react with a heavy bond at the time of irradiation with active energy rays to form a covalent bond, thereby improving adhesion.

  A urethane resin containing a carbon-carbon double bond is a urethane resin having a carbon-carbon double bond, and a solvent-free active energy ray-curable resin layer such as a prism layer or a microlens layer. Any conventionally known material can be used as long as it reacts with the carbon-carbon double bond contained in the compound forming the. For example, introduction into a urethane resin in the form of an acrylate group, a methacrylate group, a vinyl group, an allyl group or the like can be mentioned.

  Various substituents can be introduced into the carbon-carbon double bond, such as an alkyl group such as a methyl group or an ethyl group, a phenyl group, a halogen group, an ester group, an amide group, or a conjugated double bond. You may have such a structure. Further, the amount of the substituent is not particularly limited, and any of a 1-substituted product, a 2-substituted product, a 3-substituted product, or a 4-substituted product can be used. A 2-substituted product is preferable, and a 1-substituted product is more preferable.

  Considering the ease of introduction into the urethane resin and the reactivity with the carbon-carbon double bond contained in the compound that forms a solventless active energy ray-curable resin layer, such as a prism layer or a microlens layer, An acrylate group and a methacrylate group are preferable, an acrylate group and a methacrylate group having no substituent are more preferable, and an acrylate group having no substituent is particularly preferable.

  The ratio of the carbon-carbon double bond part (C = C part, molecular weight 24) to the whole urethane resin is preferably 0.5% by weight or more, more preferably 1.0% by weight or more, and further preferably 1 .5% by weight or more. When the ratio of the carbon-carbon double bond portion to the entire resin is 0.5% by weight or more, the adhesion to a solvent-free active energy ray-curable resin layer, such as a prism resin or a microlens resin, effectively, In particular, adhesion with a resin having a high refractive index is also improved.

  In forming the coating layer in the film of the present invention, various polymers other than the urethane resin can be used in combination for coating appearance, haze adjustment, particle retention, and the like.

  Conventionally known polymers can be used as the polymer. Specific examples include polyester resins, acrylic resins, polyvinyls (polyvinyl alcohol, polyvinyl chloride, vinyl chloride vinyl acetate copolymers, etc.), polyalkylene glycols, polyalkylenes. Examples include imine, methylcellulose, hydroxycellulose, and starches.

  For coating layer formation, the coating layer of the coating layer is strengthened to improve sufficient adhesion and moisture and heat resistance properties with solventless active energy ray-curable resin layers such as prism layers and microlens layers. In addition, 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. Moreover, in order to improve the adhesiveness with a functional layer more, it is also possible to use 2 or more types of crosslinking agents together. Among the above, in terms of good adhesion, oxazoline compounds, epoxy compounds, isocyanate compounds, and carbodiimide compounds are more preferable, and in particular, oxazoline compounds and epoxy compounds, oxazoline compounds and isocyanate compounds, oxazoline compounds and carbodiimide compounds. It has been found that the adhesion is remarkably improved when used 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 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, 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 comprises the laminated polyester film in this invention, a urethane resin is 20 to 90 weight% normally, Preferably it is 30 to 85 weight%, More preferably, it is the range of 45 to 75 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 constituting the laminated polyester film in the present invention, the particles are usually 3 to 70% by weight, preferably 10 to 60% by weight, more preferably 15 to 45% by weight, and further preferably 20 to 40% by weight. % Range. By using in the above range, it is possible to effectively adjust the haze.

  As a ratio in the coating layer constituting the laminated polyester film in the present invention, the component derived from the crosslinking agent is usually 80% by weight or less, preferably in the range of 5 to 60% by weight, more preferably in the range of 10 to 40% by weight. is there. By using in the said range, it becomes a favorable application | coating external appearance and a firm coating layer.

  In the polyester film of the present invention, a coating layer can also be provided on the surface opposite to the surface on which the coating layer is provided. For example, when a functional layer such as an anti-sticking layer, a light diffusion layer, or a hard coat layer is formed on the opposite side of the prism layer or the microlens layer, it is possible to improve the adhesion with the functional layer. . A conventionally well-known thing can be used as a component of the coating layer formed in the surface on the opposite side. Examples thereof include polymers such as polyester resins, acrylic resins and urethane resins, oxazoline compounds, epoxy compounds, isocyanate compounds, carbodiimide compounds, crosslinkers such as melamine compounds, etc., and these materials may be used alone. A plurality of types may be used in combination.

  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. When the film thickness is out of the above range, the coating appearance may deteriorate and the adhesion with the functional layer may deteriorate.

  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, when the coating layer is provided by off-line coating, it is usually 3 to 40 at 80 to 200 ° C. The heat treatment may be performed for 2 seconds, preferably 100 to 180 ° C. for 3 to 40 seconds.

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

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

  The amount of haze reduction due to the formation of the functional layer on the coated layer of the polyester film of the present invention is essential to be 1.0% or more, preferably 2.0% or more, more preferably 5.0%. More preferably, it is in the range of 8.0% or more, particularly 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.

  The haze of the polyester film of the present invention is not particularly limited, but is preferably 2.0% or more. When adjusting haze with particles, the way the film looks depends on the type and size of the particles used, so it cannot be said unconditionally, but in order to make it easier to distinguish between processed and unprocessed functional layers. Is preferably more than 5.0%, more preferably more than 8.0%, still more preferably more than 10%, particularly preferably more than 12%. In the scope of the present invention, it has been found that even if the haze value is the same, the smaller the average particle diameter of the particles, the more apparent haze value becomes whitish, and the distinction between functional layer processing and unprocessed I found that is easier to put.

  In general, a functional layer is formed on the coating layer of the laminated polyester film of the present invention. As a functional layer, it is a layer provided in order to provide various functions, such as a prism layer, a micro lens layer, a hard-coat layer, a light-diffusion layer, an ink layer, an adhesive layer, an adhesive bond layer, for example. Among these functional layers, the present invention is particularly suitable for a solventless active energy ray-curable resin layer used for forming a prism layer, a microlens layer, and the like. The solvent-free active energy ray-curable resin layer means that the solvent content is 5% by weight or less, more preferably 3% by weight or less, and more preferably no active solvent rays such as ultraviolet rays or electron beams. It is a functional layer formed from a curable compound. 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.

  In the film of the present invention, it is possible to provide a resin layer having a high refractive index, which is particularly difficult to ensure adhesion, and is necessary for high brightness. In recent years, various shapes have been proposed for the prism layer in order to improve the luminance efficiently. Generally, prism layers are formed by arranging prism rows having a triangular cross section in parallel. Similarly, various shapes of the microlens layer have been proposed, but in general, a large number of hemispherical convex lenses are provided on the film. Any layer can have a conventionally known shape.

  Examples of the shape of the prism layer include a triangular cross section having a thickness of 10 to 500 μm, a pitch of prism rows of 10 to 500 μm, and an apex angle of 40 ° to 100 °. Examples of the shape of the microlens layer include a hemispherical shape having a thickness of 10 to 500 μm and a diameter of 10 to 500 μm, but may have a shape such as a cone or a polygonal pyramid.

As a material used for the active energy ray-curable resin layer, conventionally known materials can be used, and examples thereof include those made of an active energy ray-curable resin, such as monofunctional (meth) acrylate, bifunctional. Examples include (meth) acrylates, polyfunctional (meth) acrylates, polyester resins, epoxy resins, polyester (meth) acrylates, epoxy (meth) acrylates, urethane (meth) acrylates, and other (meth) acrylate resins.

  The composition containing the active energy ray-curable (meth) acrylate is not particularly limited. For example, known active energy ray curable monofunctional (meth) acrylate, bifunctional (meth) acrylate, polyfunctional (meth) acrylate mixed one or more types, active energy ray curable prism and resin for microlenses What is marketed as a material, or what added the other component in the range which does not impair the objective of this embodiment other than these can be used.

  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.

The higher the refractive index of the active energy ray-curable resin layer is, the higher the luminance tends to improve, and it is usually 1.56 to 1.65, preferably 1.57 to 1.64, more preferably 1.58. It is in the range of ~ 1.63. If it is out of the above range, the luminance may not be sufficiently increased.

  Examples of the prescription for increasing the refractive index for increasing the brightness include a method using a compound having a large aromatic structure, a sulfur atom, a halogen atom, and a metal compound in addition to the above general compound. Among them, a method using a compound having a large aromatic structure or a sulfur atom is particularly preferable from the viewpoint of the environment because the refractive index of the prism layer and the microlens layer can be made uniform.

  Examples of the compound having a large aromatic structure include condensed polycyclic aromatic structures such as naphthalene, anthracene, phenanthrene, naphthacene, benzo [a] anthracene, benzo [a] phenanthrene, pyrene, benzo [c] phenanthrene, and perylene. , A compound having a biphenyl structure, a compound having a fluorene structure, and the like.

Various substituents may be introduced into the biphenyl structure, fluorene structure, and condensed polycyclic aromatic structure, and those having a benzene ring-containing substituent such as a phenyl group have a refractive index. Since it can be made higher, it is preferable. It is also possible to introduce atoms that increase the refractive index, such as sulfur atoms and halogen atoms. Furthermore, various functional groups such as an ester group, an amide group, a hydroxyl group, an amino group, and an ether group can be introduced in order to improve the adhesion with the coating layer.

  The total of the biphenyl structure, fluorene structure, condensed polycyclic aromatic structure and aromatic compounds substituted for these structures in the active energy ray-curable resin layer depends on the type and amount of other structures or the curing conditions. Therefore, although it cannot be generally stated, it is preferably in the range of 20 to 80% by weight, more preferably 25 to 70% by weight, and further preferably 30 to 60% by weight with respect to the entire active energy ray-curable resin layer. . If it is out of the above range, the luminance may decrease or the active energy ray-curable resin layer may not be formed successfully.

  The proportion of the compound having a biphenyl structure, a fluorene structure, or a condensed polycyclic aromatic structure forming the active energy ray-curable resin layer in the film of the present invention is the total non-volatile content of the compound composition forming the active energy ray-curable resin layer. As a ratio with respect to a component, Preferably it is 5 weight% or more, More preferably, it is 10 to 90 weight%, More preferably, it is the range of 20 to 80 weight%. By using in this range, a refractive index becomes high and it becomes easy to obtain high brightness | luminance.

  Other components contained in the composition containing the active energy ray-curable compound 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.

  Analysis of the components of the active energy ray-curable resin 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) Method for measuring the intrinsic viscosity of polyester 1 g of polyester from which other polymer components and pigments incompatible with polyester have been removed are precisely weighed, and 100 ml of a mixed solvent of phenol / tetrachloroethane = 50/50 (weight ratio) is added. And dissolved at 30 ° C.

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

(3) Method for measuring film thickness of coating layer The surface of the coating layer was dyed with RuO ₄ and embedded in an epoxy resin. Thereafter, the section prepared by ultramicrotomy stained with RuO _4, a coating layer cross-section was measured by using a TEM (Hitachi High Technologies Corporation H-7650, accelerating voltage 100 V). The film thickness was measured at a location not including the particle portion.

(4) Measuring method of refractive index The ultraviolet curable resin compound was arrange | positioned flat with a film thickness of 10 micrometers on the application layer side, and it hardened | cured with the ultraviolet-ray, and formed the flat ultraviolet curable resin layer. The refractive index on the ultraviolet curable resin layer side was measured using a refractometer (SL-NA-B manufactured by Atago Co., Ltd.).

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

(6) Method of measuring haze reduction when functional layer is formed As a functional layer, on a flat metal plate, 30 parts by weight of 2-biphenoxyethyl acrylate, 4,4 ′-(9-fluorenylidene) bis (2 -Phenoxyethyl acrylate) 17 parts by weight, ethylene glycol-modified bisphenol A acrylate (ethylene glycol chain = 8) 40 parts by weight, trimethylolpropane triacrylate 10 parts by weight, diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide 3 parts by weight The laminated polyester film was placed in such a direction that the coating layer was in contact with the resin, and the composition was uniformly stretched by a roller, and the resin was cured by irradiating ultraviolet rays from an ultraviolet irradiation device. . Next, the film was peeled off from the metal plate to obtain a film on which a functional layer having a thickness of 2 μm (the refractive index of the layer was 1.59 and the haze was 0.1%) was formed. 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.

(7) Discrimination evaluation method before and after functional layer processing The difference between the 20 cm × 20 cm film before and after forming the functional layer of (6) 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 more than two points.

(8) Method for evaluating adhesion of coating layer: On a flat metal plate, 30 parts by weight of 2-biphenoxyethyl acrylate, 17 parts by weight of 4,4 ′-(9-fluorenylidene) bis (2-phenoxyethyl acrylate), ethylene A composition comprising 40 parts by weight of a glycol-modified bisphenol A acrylate (ethylene glycol chain = 8), 10 parts by weight of trimethylolpropane triacrylate, and 3 parts by weight of diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide is disposed. The laminated polyester film was laminated in the direction in which the coating layer was in contact with the resin from above, the composition was uniformly stretched by a roller, and the resin was cured by irradiating ultraviolet rays from an ultraviolet irradiation device. Subsequently, the film was peeled off from the metal plate to obtain a film on which a functional layer (refractive index = 1.59) having a thickness of 2 μm was formed. Thereafter, the functional layer of the film after being treated for 24 hours in an environment of 60 ° C. and 90% RH was scratched with a cutter knife at an interval of 5 mm, and a 18 mm wide tape (Cello Tape (registered trademark) CT- manufactured by Nichiban Co., Ltd.) 18) was affixed and peeled off rapidly at a peeling angle of 180 degrees. The peeled surface was observed. If the peeled area was less than 5%, ◎ was marked if it was 5% or more but less than 20%, Δ if it was 20% or more and less than 50%, and x if it was 50% or more.

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

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

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

Examples of compounds constituting the coating layer are as follows.
(Example compounds)
・ Urethane resin with carbon-carbon double bond: (IA)
Hydroxyethyl acrylate unit: dicyclohexylmethane diisocyanate unit: hexamethylene diisocyanate trimer unit: caprolactone unit: ethylene glycol unit: dimethylolpropanoic acid unit = 18: 12: 22: 26: 18: 4 (mol%) A urethane resin having a carbon-carbon double bond weight of 2.0% by weight.

-Urethane resin having a carbon-carbon double bond: (IB)
Hydroxyethyl acrylate unit: dicyclohexylmethane diisocyanate unit: hexamethylene diisocyanate trimer unit: caprolactone unit: ethylene glycol unit: dimethylolpropanoic acid unit = 6: 10: 20: 38: 22: 4 (mol%) A urethane resin having a carbon-carbon double bond weight of 0.7% by weight.

-Urethane resin without carbon-carbon double bond: (IC)
80 parts by weight of polycarbonate polyol consisting of 1,6-hexanediol and diethyl carbonate having a number average molecular weight of 2000, 4 parts by weight of polyethylene glycol having a number average molecular weight of 400, 12 parts by weight of methylenebis (4-cyclohexylisocyanate), dimethylolbutanoic acid 4 An aqueous dispersion obtained by neutralizing a urethane resin consisting of parts by weight with triethylamine.

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

Acrylic resin: (IE) Acrylic resin aqueous dispersion 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)

・ Particles: (IIA) Silica particles with an average particle size of 0.15 μm ・ Particles: (IIB) Silica particles with an average particle size of 0.20 μm ・ Particles: (IIC) Silica particles with an average particle size of 0.30 μm ・ Particles: (IID ) Silica particles with an average particle size of 0.45 μm

・ 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.)

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 peripheral speed of the roll, and then the coating solution 1 shown in Table 1 below was applied to one side of the longitudinally stretched film, which was led to a tenter. Thickness having a coating layer in which the film is stretched 4.0 times at 120 ° C. in the transverse direction and heat-treated at 225 ° C., then relaxed by 2% in the transverse direction, and the coating layer thickness (after drying) is 0.06 μm. A 125 μm polyester film was obtained.

  When the obtained polyester film was evaluated, the haze was 2.0% and the haze reduction amount was 1.4%, and it was possible to discriminate between a film without a functional layer and a film with a functional layer formed. there were. Moreover, the adhesiveness with a functional layer was also favorable. The properties of this film are shown in Table 2 below.

Examples 2-24:
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. Moreover, the adhesiveness with a functional layer was also favorable.

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 2-8:
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 finished polyester film was evaluated, as shown in Table 2 below, when the discriminability between the film in which the functional layer is not formed and the film in which the functional layer is formed is not sufficient, or when the adhesion is poor. there were.

  The film of the present invention is used for forming a functional layer such as a solvent-free active energy ray-curable resin layer used for forming a prism layer or a microlens layer, for example. It can be suitably used for applications where it is desired to easily distinguish.

Claims (7)

A polyester film having a coating layer containing a urethane resin on at least one surface. When a functional layer is formed on the coating layer, the haze is reduced by 1.0% or more, and the functional layer is a prism layer, a microlens. A laminated polyester film, which is a layer selected from a layer, a hard coat layer, a light diffusion layer, an ink layer, an adhesive layer and an adhesive layer. The laminated polyester film according to claim 1, wherein the functional layer is composed of a solventless active energy ray-curable resin layer. The member for backlight units which formed the functional layer on the laminated polyester film of Claim 1 or 2. When a coating layer containing a urethane resin is formed on at least one surface of the polyester film, and the functional layer is formed on the coating layer, the haze is reduced by 1.0% or more, so that the functional layer is processed / unprocessed. The determination method to determine. It has a step of forming a coating layer containing a urethane resin by in-line coating on at least one surface of the polyester film, and when a functional layer is formed on the coating layer, the haze is reduced by 1.0% or more. A method for producing a laminated polyester film. The method for producing a laminated polyester film according to claim 5, wherein the coating layer and the polyester film are stretched in at least one direction. The manufacturing method of the laminated polyester film of Claim 5 or 6 which heat-processes on 70-270 degreeC conditions .