JP6485274B2 - Laminated polyester film - Google Patents

Description

  The present invention relates to a laminated polyester film. For example, in an application for forming a functional layer such as a hard coat layer such as a transparent electrode such as a touch panel or a film for molding, it is easy to distinguish between processing and unprocessed functional layers. Therefore, the present invention relates to a laminated polyester film suitable for the purpose.

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

  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 is a possibility of mistaken goods and raw products.

JP 2005-97571 A

  The present invention has been made in view of the above circumstances, and the problem to be solved is that in the application of forming a functional layer such as a hard coat layer, it is possible to easily distinguish between processing and unprocessed functional layers. The object is to provide an excellent laminated polyester film.

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

That is, the gist of the present invention is that a polyester film has a coating layer (excluding those containing organic fine particles having an average primary particle diameter of 250 nm or more) on at least one surface , and the coating layer surface has an arithmetic average roughness (Sa ) is more than 25 nm, exist fine irregularities to be 60nm or less consists in the laminated polyester film reduction amount of haze values according to the following measurement method is characterized in that 1.0% or more.

Measurement method: As functional layer, dipentaerythritol hexaacrylate 80 parts by weight, 2-hydroxy-3-phenoxypropyl acrylate 20 parts by weight, photopolymerization initiator (trade name: Irgacure 184, manufactured by Ciba Specialty Chemicals) 5 parts by weight A mixed coating solution of 200 parts by weight of methyl ethyl ketone was applied on the coating layer so as to have a dry film thickness of 2 μm, and a hard coat layer was formed by irradiating with ultraviolet rays to form a hard coat layer, and haze in accordance with JIS K 7136. The value is measured, and the difference from the haze value of the laminated polyester film before forming the functional layer is calculated.

  According to the laminated polyester film of the present invention, by forming various functional layers such as a hard coat layer, the base film that can greatly distinguish the processed / unprocessed functional layer by greatly reducing haze The 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 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 the present invention, it has a coating layer, and when the functional layer is formed on the coating layer, it has a coating layer in which fine irregularities having a surface arithmetic average roughness (Sa) of 25 nm or more are present, When a functional layer is formed on the coating layer, it is an essential requirement that the haze value be reduced by 1.0% or more.

  The film of the present invention is designed to facilitate the distinction between processing and unprocessed functional layers by reducing haze after forming a functional layer such as a hard coat layer.

  In order to reduce the haze value by 1.0% or more when the functional layer is formed on the coating layer, the surface unevenness formed by the polyester film or coating layer of the base material is reduced by forming the functional layer. The method 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.

  In the present invention, in the three-dimensional roughness parameter, it is essential that the arithmetic average roughness (Sa) of the coating layer surface is in a range of 25 nm or more.

  Specifically, the arithmetic average roughness (Sa) is obtained by expanding two-dimensional Ra to three dimensions, and dividing the volume of the portion surrounded by the surface shape curved surface and the average surface by the measurement area. Yes, it is obtained from the following equation. When the surface is the XY plane and the height direction is the Z-axis, A: defined area (the whole image), Z (x, y): the image point (x, y) from the zero height plane Assuming height, it is shown by the following formula.

  Further, as a preferable form, the surface height distribution and squeeze (Sku) is 12 or less.

  The surface height distribution and curl (Sku) is a measure of the sharpness of the surface shape curved surface and characterizes the spread of the surface height distribution, and is defined by the following equation.

  In the above formula, Sq is an extension of two-dimensional Rq (RMS) to three dimensions, which represents the standard deviation σ in statistics. This is the root mean square deviation obtained by dividing the volume of the surface shape curved surface and the mean surface by the square and the volume of the part sandwiched by the mean surface and dividing the measured area by the square root, and can be obtained from the following equation .

  When Sku is 3, it represents a normal distribution. As this value decreases, the surface height distribution has a gentle shape, and as the value increases, the protrusion becomes sharper. .

  Examples of the method for forming the surface irregularities in which the haze is lowered by the functional layer include a method for forming irregularities on the coating layer itself and a method for containing particles.

  Examples of the method for forming irregularities on the coating layer itself include, for example, a method of forming a coating layer by mixing anionic and cationic polymers, or a film stretching step by applying a polymer having a high glass transition temperature (Tg). The method of forming a coating layer through this is mentioned. A method of forming a coating layer by mixing anionic and cationic polymers is preferable because surface irregularities can be formed effectively.

  In the case of the method of containing particles in the coating layer, since the particles may easily fall off from the coating layer as the amount of contained particles increases, a method of making the coating layer itself uneven is preferable. In addition, since the surface area is increased by providing irregularities on the surface of the coating layer, there is also an effect that it is possible to contribute to improvement in adhesion with the functional layer.

  The Tg of the polymer used in the coated layer of the polyester film of the present invention is usually 50 ° C. or higher, preferably 60 ° C. to 150 ° C., more preferably 70 ° C. to 130 ° C. By using the polymer in the above range, irregularities are formed in the coating layer itself by the film stretching step, and a film having a high haze can be obtained.

In order to form unevenness on the surface of the coating layer, various polymers can be used, and conventionally known polymers can be used as the polymer. Specific examples of the polymer include polyester resin, acrylic 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 more preferable to use an acrylic resin, a urethane resin, or a polyester resin from the viewpoints of forming irregularities on the surface of the coating layer, improving adhesion with a functional layer such as a hard coat layer, and improving coating appearance. From the viewpoint of good adhesion to various functional layers, it is more preferable to use an acrylic resin or a urethane resin.

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

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

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

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

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

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

  Among the above polyols, polycarbonate polyols and polyester polyols are more preferably used in order to improve 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 polyurethane resin, a carboxyl group from which the neutralizing agent has been removed in the drying step after coating can be used as a crosslinking reaction point by another crosslinking agent. Thereby, it is possible to further improve the durability, solvent resistance, water resistance, blocking resistance, and the like of the obtained coating layer, as well as excellent stability in a liquid state before coating.

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

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

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

  Moreover, in order to improve the intensity | strength of an application layer, it is also possible to use a crosslinking agent together. A conventionally well-known material can be used with a crosslinking agent, For example, an oxazoline compound, an epoxy compound, a melamine compound, an isocyanate type compound, a carbodiimide type compound, a silane coupling compound etc. are mentioned. In addition, two or more kinds of crosslinking agents can be used in combination in order to improve the adhesion to the functional layer. From the viewpoint of good adhesion, among these, oxazoline compounds, epoxy compounds, melamine compounds, isocyanate compounds, and carbodiimide compounds are preferable, and particularly selected from oxazoline compounds, epoxy compounds, melamine compounds, isocyanate compounds, and carbodiimide compounds. It is more preferable to use two or more kinds of cross-linking agents in combination because the adhesion is remarkably improved. Moreover, a melamine compound is more preferable from the viewpoint of increasing the strength of the coating layer.

  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 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.

  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.

  These cross-linking agents are used in a design that improves the performance of the coating layer by reacting in the drying process or film forming process. It can be inferred that unreacted products of these crosslinking agents, compounds after the reaction, or mixtures thereof exist in the finished coating layer.

  In the coating layer of the polyester film of the present invention, it is preferable to use particles in combination with the formation of the coating layer in order to improve slipperiness and blocking. The average particle diameter of the particles is preferably in the range of 0.001 μm to 1.0 μm, more preferably 0.005 μm to 0.5 μm, and still more preferably 0.01 μm to 0.2 μm.

  Examples of the particles used include inorganic particles such as silica, alumina and metal oxide, or organic particles such as crosslinked polymer particles. In particular, silica particles are preferred from the viewpoint of dispersibility in the 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 with respect to all the non-volatile components in the coating liquid which forms the coating layer which comprises the laminated polyester film in this invention, a polymer becomes like this. Preferably it is 97 weight% or less, More preferably, it is the range of 20-95 weight%, More preferably, 30- It is in the range of 90% by weight. By using in the said range, there exists an effect in formation of the unevenness | corrugation of the coating layer surface.

  As a ratio with respect to all the non-volatile components in the coating liquid which forms the coating layer which comprises the laminated polyester film in this invention, Preferably a crosslinking agent is 45 weight% or less, More preferably, it is the range of 3-35 weight%, More preferably It is in the range of 5 to 25% by weight. By using in the said range, in addition to formation of the unevenness | corrugation of the coating layer surface, a firm coating layer can be obtained.

  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. 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 0.03 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 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 decrease in haze value 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, and further preferably 5.0% or more. Especially preferably, it is 8.0% or more, Most preferably, it is 10% or more of range. 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 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.

  The arithmetic average roughness (Sa) of the unevenness formed on the coating layer of the polyester film of the present invention is essential to be 25 nm or more, preferably 35 nm or more, more preferably 42 nm or more, and further preferably 46 nm or more. It is a range. The upper limit of the preferable range is 60 nm. Further, the height (Sku) of the surface height distribution is preferably 12 or less, more preferably 9 or less, still more preferably 6 or less, and particularly preferably 4 or less. As the lower limit of the preferred range, Sku is 1. By setting the above range, a film having a high haze can be obtained by forming irregularities on the surface of the coating layer.

  In the polyester film of the present invention, a functional layer is generally formed on the coating layer. As a functional layer, it is a layer provided in order to provide various functions, such as a hard-coat layer, a light-diffusion layer, a prism layer, a micro lens layer, an ink layer, an adhesive layer, an adhesive bond layer, for example. 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, Most preferably, it is 0.5% or less of range. Similarly, the thickness of the functional layer is not particularly limited as long as the haze decreases when formed on the coating layer, but is preferably 0.1 to 50 μm, more preferably 1 to 15 μm, and still more preferably 1 to 1 μm. The range is 8 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 xylalkyl (meth) acrylate, benzyl (meth) acrylate, aromatic (meth) acrylate such as phenoxyethyl (meth) acrylate, diaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, Methoxyethylene glycol (meth) acrylate, phenoxy polyethylene glycol (meth) acrylate, ethylene oxide modified (meth) acrylate such as phenylphenol ethylene oxide modified (meth) acrylate, glycidyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, Examples include (meth) acrylic acid.

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

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

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

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

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

(1) 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 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 of a mixed coating solution of 200 parts by weight of methyl ethyl ketone was applied so as to have a dry film thickness of 2 μm and hardened by irradiating with ultraviolet rays (the layer concerned) The haze was 0.1%), 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 formation of the functional layer of (5) above was observed. As a method of observation, the difference between the two was confirmed when holding a film without a hard coat layer and a film with a hard coat layer in both hands and observing under a fluorescent lamp. The case where the difference can be discriminated instantaneously is marked as ◎, the case where it can be easily discriminated by observation for 3 seconds, the case where it can be discriminated when looking closely, Δ, and the case where it is difficult or impossible to discriminate.

(7) Arithmetic mean surface roughness (Sa), sharpness of surface height distribution (Sku)
The three-dimensional surface roughness of the surface was measured by measuring the surface shape and surface roughness in a 260 μm × 260 μm region using a laser microscope “LEXT OLS-4000” manufactured by Olympus Corporation.

(8) Evaluation method of adhesion of coating 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. ) A mixed coating solution of 5 parts by weight and 200 parts by weight of methyl ethyl ketone was applied so as to have a dry film thickness of 5 μm and cured by irradiating with ultraviolet rays to form a hard coat layer. The obtained film was subjected to 10 × 10 cross-cut after 50 hours in an environment of 80 ° C. and 90% RH, and a tape of 18 mm width (cello tape (registered trademark) CT manufactured by Nichiban Co., Ltd.) was formed thereon. -18) is attached, and the peeled surface is observed after abrupt peeling at a 180 degree peel angle. If the peeled area is less than 10%, it is ◯ if it is 10% or more and less than 30%, and if it is 30% or more. X.

The polyester used in the examples and comparative examples was prepared as follows.
<Method for producing polyester (A)>
100 parts by weight of dimethyl terephthalate, 60 parts by weight of ethylene glycol, 30 ppm of ethyl acid phosphate with respect to the resulting polyester, and 100 ppm of magnesium acetate tetrahydrate with respect to the resulting polyester as the catalyst at 260 ° C. in a nitrogen atmosphere at 260 ° C. The reaction was allowed to proceed. Subsequently, 50 ppm of tetrabutyl titanate was added to the 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)

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

・ Urethane resin (IB)
Carbonic urethane resin aqueous dispersion formed from hydrogenated diphenylmethane diisocyanate unit: terminal OH-modified polyhexamethylene carbonate unit: dioxyethyldimethylammonium salt unit = 30: 57: 13 (mol%).

・ Oxazoline compounds: (IIA)
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: (IIB) polyglycerol polyglycidyl ether

Melamine compound: (IIC) hexamethoxymethylol melamine

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

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. and then relaxed by 2% in the transverse direction and the coating layer thickness (after drying) is 0.10 μm. A 125 μm polyester film was obtained.

  When the obtained polyester film was evaluated, the haze was as high as 7.2%, the haze reduction amount was 6.6%, and the discriminability between the film in which the functional layer was not formed and the film in which the functional layer was formed was It was good. The properties of this film are shown in Table 2 below.

Examples 2-9:
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, the results were inferior in discriminability between a film in which a functional layer was not formed and a film in which a functional layer was formed.

Comparative Examples 2-3:
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.

  The film of the present invention is suitable for use in forming a functional layer such as a hard coat layer, such as a transparent electrode such as a touch panel or a film for molding, and in an application where it is desired to easily distinguish between processed and unprocessed functional layers. Can be used.

Claims (15)

The polyester film has a coating layer (excluding those containing organic fine particles having an average primary particle size of 250 nm or more) on at least one side, and the coating layer surface has an arithmetic average roughness (Sa) of 25 nm or more and 60 nm or less . fine irregularities composed exists and laminated polyester film reduction amount of haze values according to the following measurement method is characterized in that 1.0% or more.

Measurement method: As functional layer, dipentaerythritol hexaacrylate 80 parts by weight, 2-hydroxy-3-phenoxypropyl acrylate 20 parts by weight, photopolymerization initiator (trade name: Irgacure 184, manufactured by Ciba Specialty Chemicals) 5 parts by weight A mixed coating solution of 200 parts by weight of methyl ethyl ketone was applied on the coating layer so as to have a dry film thickness of 2 μm, and a hard coat layer was formed by irradiating with ultraviolet rays to form a hard coat layer, and haze in accordance with JIS K 7136. The value is measured, and the difference from the haze value of the laminated polyester film before forming the functional layer is calculated. The polyester film has a coating layer (excluding those containing organic fine particles having an average primary particle size of 250 nm or more) on at least one side, and the coating layer surface has an arithmetic average roughness (Sa) of 25 nm or more and 60 nm or less . fine irregularities composed exists and laminated polyester film reduction amount of haze values according to the following measurement method is characterized in that it comprises by 1.0% or more, the determination function of processing and raw functional layer.

Measurement method: As functional layer, dipentaerythritol hexaacrylate 80 parts by weight, 2-hydroxy-3-phenoxypropyl acrylate 20 parts by weight, photopolymerization initiator (trade name: Irgacure 184, manufactured by Ciba Specialty Chemicals) 5 parts by weight A mixed coating solution of 200 parts by weight of methyl ethyl ketone was applied on the coating layer so as to have a dry film thickness of 2 μm, and a hard coat layer was formed by irradiating with ultraviolet rays to form a hard coat layer, and haze in accordance with JIS K 7136. The value is measured, and the difference from the haze value of the laminated polyester film before forming the functional layer is calculated. At least one surface coating layer of the polyester film, the coating layer surface has an arithmetic mean roughness (Sa) is 25nm or more, exist fine irregularities to be 60nm or less, the amount of decrease in haze value by the following measurement methods Is 1.0% or more, and the point (Sku) of the surface height distribution of the coating layer is 1 or more and 12 or less .

Measurement method: As functional layer, dipentaerythritol hexaacrylate 80 parts by weight, 2-hydroxy-3-phenoxypropyl acrylate 20 parts by weight, photopolymerization initiator (trade name: Irgacure 184, manufactured by Ciba Specialty Chemicals) 5 parts by weight A mixed coating solution of 200 parts by weight of methyl ethyl ketone was applied on the coating layer so as to have a dry film thickness of 2 μm, and a hard coat layer was formed by irradiating with ultraviolet rays to form a hard coat layer, and haze in accordance with JIS K 7136. The value is measured, and the difference from the haze value of the laminated polyester film before forming the functional layer is calculated. The polyester film has a coating layer (excluding those containing organic fine particles having an average primary particle size of 250 nm or more) on at least one side, and the coating layer surface has an arithmetic average roughness (Sa) of 25 nm or more and 60 nm or less . fine irregularities composed exists and has a hard coat layer on the coating layer, when forming the hard coat layer on the coating layer, and wherein the haze value is lowered more than 1.0% Laminated polyester film. The laminated polyester film according to any one of claims 1 to 3, further comprising a functional layer on the coating layer. The laminated polyester film according to claim 5 , wherein the functional layer is a hard coat layer. The laminated polyester film according to claim 6 , wherein the hard coat layer is a polymerized cured product of a composition containing an active energy ray-curable (meth) acrylate. Laminated polyester film according to claim 1 or 2 Kurtosis of surface height distribution of the coating layer (Sku) is 12 or less. The laminated polyester film according to any one of claims 1 to 8 , wherein the coating layer is a layer formed by using a crosslinking agent in combination. Laminated polyester film according to any one of claims 1 to 9, wherein the coating layer contains particles. The coating layer is laminated polyester film according to any one of claims 1 to 10, containing an acrylic resin or urethane resin. A transparent electrode formed by using the laminated polyester film according to any one of claims 1 to 11. Molding a film made by using a laminated polyester film according to any one of claims 1 to 12. At least one side of the polyester film is formed with an in-line coating layer (except for those containing organic fine particles having an average primary particle size of 250 nm or more) by in-line coating in the film manufacturing process, and at least one of the coating layer and the polyester film is formed. and a step of stretching, the said coating layer surface has an arithmetic mean roughness (Sa) is 25nm or more, it exists fine irregularities to be 60nm or less, a hard coat layer as a functional layer on the coating layer When manufacturing, the haze value falls 1.0% or more, The manufacturing method of the laminated polyester film characterized by the above-mentioned. On at least one surface of the polyester film, comprising the step of forming the coating layer through a heat treatment at 100 to 180 ° C. (except those having an average primary particle diameter contains more organic fine particles 250 nm), the coating layer surface has an arithmetic average roughness (Sa) is 25nm or more, exist fine irregularities to be 60nm or less, when forming the hard coat layer as a functional layer on the coating layer, the haze value is lowered more than 1.0% A method for producing a laminated polyester film characterized by the above.