JP2006231658A - Laminated polyester film for optical resin solution film-making - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laminated polyester film for optical resin solution film-making which is excellent in mold-release properties of an optical resin film, luminescent spot fault, and transparency. <P>SOLUTION: In the laminated polyester film for optical resin solution film-making, a laminated film comprising a composition (A) and an acrylic resin (B) having a 12-25C alkyl chain is formed on at least one side of a polyester film. The composition (A) is a composition comprising polythiophene and a polyanion and/or a composition comprising a polythiophene derivative and a polyanion, and the number of internal foreign matter of at least 100 μm contained in the laminated polyester film is below 10/m<SP>2</SP>. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  TECHNICAL FIELD The present invention relates to a laminated polyester film for forming an optical resin solution, and more specifically, an optical resin that is excellent in releasability and transparency of an optical resin film and can reduce bright spot defects. The present invention relates to a laminated polyester film for solution casting.

  Optical films used for liquid crystal display devices and optical disks are required to have characteristics such as high heat resistance and low hygroscopicity in addition to being colorless and transparent and having low birefringence. In recent years, polymethyl methacrylate resins, polycarbonates and alicyclic polyolefins have attracted attention as optical resins. These resins are materials with excellent heat resistance, transparency and low hygroscopicity, and are polymers with a small photoelastic coefficient. Therefore, films using these polymers are less susceptible to retardation unevenness and light weight parts. It is a preferable material for the conversion.

  As a method for forming a film using an optical resin such as polycarbonate or alicyclic polyolefin, a melting method such as a melt extrusion method or a melt injection method has been mainly used. A solution method is known as a film forming method different from the melting method. The solution method is a method in which a resin is dissolved or dispersed in a solvent, and then cast or coated on a support (carrier) and dried to form a film. It is necessary to apply a high temperature to the resin as in the melting method. The film can be molded under mild conditions, and the film being molded is less susceptible to stress, so that there is an advantage that a film molded body with less in-plane variation in optical properties such as retardation can be obtained.

  The solution method is a molding method that is particularly excellent as a method for producing an optical film because a film having a small thickness unevenness and a high surface property can be obtained.

  In the case of forming these resins in solution, a method using toluene as a solvent is known, but since the boiling point of toluene is as high as 100 ° C. or higher, it is a high temperature for industrial production of a final product with few residual volatile components. In this case, the resin may be colored or the flatness may be deteriorated (see Patent Document 1).

  On the other hand, when a solvent having a low boiling point and high volatility is used for dissolution, it is not necessary to dry at high temperature, but the solvent from the solution is likely to volatilize, and the film naturally peels off from the support during drying on the support. There is a problem that it ends up. The natural peeling of the film from the support leads to a problem that continuous production cannot be performed or the film cannot be wound into a roll.

One solution is to adjust the surface roughness of the support so that peeling does not occur easily. However, in order to obtain a highly transparent optical film, the surface of the support is preferably as smooth as possible so that the surface of the casting support is not transferred onto the product film. Is naturally limited (see Patent Document 2).
Japanese Patent Laid-Open No. 9-12001 JP 2002-326240 A

  However, in the above-mentioned technique, the method of dissolving polycarbonate or alicyclic polyolefin in a highly volatile solvent and forming a film by a solution method has a problem in that a highly transparent film is stably obtained. In particular, a method for obtaining a long film has not been established.

  Accordingly, an object of the present invention is to provide a laminated polyester film for forming an optical resin solution, which is excellent in releasability and transparency of an optical resin film and can reduce bright spot defects.

The laminated polyester film for optical resin solution film-forming of the present invention has a laminated film comprising the composition (A) and an acrylic resin (B) having an alkyl chain having 12 to 25 carbon atoms on at least one side of the polyester film. A laminated polyester film provided, wherein the composition (A) is a composition comprising a polythiophene and a polyanion and / or a composition comprising a polythiophene derivative and a polyanion, and in the laminated polyester film It is a laminated polyester film for forming an optical resin solution, wherein the number of contained internal foreign matters having a particle size of 100 μm or more is less than 10 / m ² .

  According to the preferable aspect of the laminated polyester film for optical resin solution casting of the present invention, the three-dimensional centerline average roughness (SRa) of at least one surface of the laminated polyester film is 3 to 20 nm, and the three-dimensional ten-point average The roughness (SRz) is 1000 nm or less.

  Moreover, according to the preferable aspect of the laminated polyester film for optical resin solution casting of the present invention, the laminated film further contains an epoxy-based crosslinking agent and / or a reaction product (C) thereof, and In addition, it is included that the total amount of the epoxy-based crosslinking agent and / or the reaction product (C) thereof is 50 to 95% by weight with respect to the composition (A) in terms of solid content by weight.

  Moreover, according to the preferable aspect of the laminated polyester film for optical resin solution film forming of this invention, the acrylic resin (B) which has a C12-C25 alkyl chain in the said laminated film is a composition ( It is contained in an amount of 10 to 40 parts by weight with respect to a total of 100 parts by weight of A) and the epoxy crosslinking agent and / or reaction product (C) thereof.

  The laminated polyester film for optical resin solution film formation of the present invention is suitably used for solution film formation of polycarbonate or alicyclic polyolefin.

  The laminated polyester film for film formation of an optical resin solution of the present invention is very useful as a laminated polyester film for film formation of an optical resin solution having excellent flatness, transparency and antistatic properties and excellent handling properties.

  The laminated polyester film for optical resin solution film-forming of the present invention comprises a composition comprising a polythiophene and a polyanion and / or a composition comprising a polythiophene derivative and a polyanion (composition (A)) on at least one side of the polyester film. ) And a laminated polyester film provided with a laminated film made of an acrylic resin (B) having an alkyl chain having 12 to 25 carbon atoms.

  The polyester constituting the laminated polyester film used in the present invention is a general term for polymer compounds having an ester bond as the main bond chain, and preferred polyesters are ethylene terephthalate, propylene terephthalate, ethylene-2,6. -At least one component selected from naphthalate, butylene terephthalate, propylene-2,6-naphthalate, ethylene-α, β-bis (2-chlorophenoxy) ethane-4,4'-dicarboxylate, etc. It is the main component. These constituent components may be used singly or in combination of two or more. Among them, it is particularly preferable to use a polyester having ethylene terephthalate as a main constituent component, considering quality and economy in general. . These polyesters may be further partially copolymerized with other dicarboxylic acid components and diol components, preferably 20 mol% or less.

  Further, in this polyester, various additives such as antioxidants, heat stabilizers, weathering stabilizers, ultraviolet absorbers, infrared absorbers, organic lubricants, pigments, dyes, organic or inorganic fine particles, packing An agent, an antistatic agent, a nucleating agent, and the like may be appropriately selected and added.

  The intrinsic viscosity (measured in o-chlorophenol at 25 ° C.) of the polyester described above is preferably in the range of 0.4 to 1.2 dl / g, more preferably 0.5 to 0.8 dl / g. It is a range.

  The thickness of the laminated polyester film is not particularly limited and is appropriately selected depending on the application, but is usually preferably 1 to 500 μm, more preferably 10 to 300 μm from the viewpoint of mechanical strength and handling properties. And most preferably 30 to 200 μm.

  The laminated polyester film for optical resin solution film formation is a film used as a base film used when the optical resin solution is formed into a film, and in the case of the present invention, it consists of a specific polyester film, and is a laminated film. In the state where is provided, it is preferably biaxially oriented. A biaxially oriented polyester film is generally an unstretched polyester sheet or film that is stretched about 2.5 to 5 times in the longitudinal and width directions, and then heat treated to complete crystal orientation. Which is a biaxially oriented pattern by wide-angle X-ray diffraction.

  The polyester film may be a composite film obtained by coextrusion. In particular, when the composite film is composed of two or more layers, for example, easy slipping fine particles are added to the skin layer, and the core layer is made non-particulate. Furthermore, when a three-layer composite film is used, for example, when easy-to-slip fine particles are added to the skin layer and the core layer uses no particles or a recovered raw material, it is easy to achieve both slipperiness and surface roughness. There are advantages such as. On the other hand, the obtained film can be bonded by various methods and used as a composite film.

  In the present invention, the laminated film provided on the polyester film is a laminated film comprising the composition (A) and an acrylic resin (B) having an alkyl chain having 12 to 25 carbon atoms, and the composition (A) Is a composition comprising a polythiophene and a polyanion and / or a composition comprising a polythiophene derivative and a polyanion.

  In the present invention, the composition further contains an epoxy crosslinking agent and / or its reaction product (C), that is, the composition (A) in the laminated film and an alkyl chain having 12 to 25 carbon atoms. The content of the acrylic resin (B) and the epoxy crosslinking agent and / or the reaction product (C) thereof is preferably 50% by weight or more, more preferably 70% by weight or more, and most preferably Preferably it is 80 weight% or more.

  In the present invention, the composition (A) constituting the laminated film preferably comprises polythiophene and a polythiophene derivative.

  In the present invention, the composition (A) that can be used for the laminated film of the laminated polyester film has the following general formula (1):

And / or the following general formula (2)

Can be obtained by polymerizing in the presence of a polyanion.

  In the general formula (1), r1 and r2 each independently represent a hydrogen element, an aliphatic hydrocarbon group having 1 to 12 carbon atoms, an alicyclic hydrocarbon group, or an aromatic hydrocarbon group. Examples thereof include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a cyclohexylene group, and a benzene group. In Chemical Formula 2, n is an integer of 1 to 4.

  In the present invention, it is preferable to use a polythiophene and / or a polythiophene derivative (n is an integer of 1 to 4) having the structural formula represented by the general formula (2), for example, n = 1 (methylene group), n = 2 (ethylene group) and n = 3 (propylene group) are preferred. Among them, a particularly preferable compound is an ethylene group compound with n = 2, that is, poly-3,4-ethylenedioxythiophene.

  In the present invention, examples of the polythiophene and / or polythiophene derivative include compounds having a structure in which the positions of the 3-position and 4-position of the thiophene ring are substituted, and as described above, the 3-position and 4-position carbon atoms And compounds having an oxygen atom bonded thereto. In the case where a hydrogen atom or a carbon atom is bonded directly to the carbon atom, it may be difficult to make the coating liquid aqueous.

  Next, in the present invention, polyanion will be described in the composition (A) used for the laminated film of the laminated polyester film.

  The polyanion used in the composition (A) in the present invention is an acidic polymer in a free acid state, and examples thereof include a high molecular carboxylic acid, a high molecular sulfonic acid, and a polyvinyl sulfonic acid. Examples of the polymer carboxylic acid include polyacrylic acid, polymethacrylic acid, and polymaleic acid. Examples of the polymer sulfonic acid include polystyrene sulfonic acid. In particular, polystyrene sulfonic acid is electrically conductive. Most preferably used. In the present invention, the free acid may take the form of a partially neutralized salt.

  By using these polyanions at the time of polymerization, it is considered that a polythiophene compound that is originally insoluble in water is easily dispersed in water or made water-based, and that the function as an acid also functions as a doping agent for the polythiophene compound. .

  In the present invention, the polymer carboxylic acid and polymer sulfonic acid can be used in the form of copolymerization with other copolymerizable monomers such as acrylic acid ester, methacrylic acid ester and styrene.

  The molecular weight of the polymer carboxylic acid or polymer sulfonic acid used as the polyanion is not particularly limited, but the weight average molecular weight is preferably 1,000 to 1,000,000, more preferably from the viewpoint of the stability and conductivity of the coating agent. 5,000 to 150,000. As long as the properties of the present invention are not impaired, alkali salts such as lithium salts and sodium salts, ammonium salts, and the like may be partially included. Even in the case of neutralized salts, polystyrene sulfonic acid and ammonium salts, which function as very strong acids, are known to shift to the acidic side due to the progress of the equilibrium reaction after neutralization. I think that acts as.

  In the present invention, the poly anion is preferably present in excess of the solid content weight ratio with respect to the polythiophene or polythiophene derivative from the viewpoint of conductivity, and the polythiophene and / or polythiophene derivative is 1 part by weight, The polyanion is more than 1 part by weight, preferably 5 parts by weight or less, more preferably more than 1 part by weight and 3 parts by weight or less. Of course, other components may be used in the composition (A) as long as the effects of the present invention are not impaired.

  The composition (A) described above is, for example, disclosed in JP-A-6-295016, JP-A-7-292081, JP-A-1-135521, JP-A-2000-6324, European Patent EP602713 and Although it can be produced by the method described in US Pat. No. 5,391,472, etc., it may be produced by a method other than these. For example, as an aqueous coating liquid of a composite composed of poly-3,4-ethylenedioxythiophene / polystyrene sulfonic acid, Bayer / H. C. A product sold as “Baytron” P from Starck (Germany) can be used.

  The composition (A) used in the present invention, for example, after obtaining 3,4-ethylenedioxythiophene using an alkali metal salt of 3,4-dihydroxythiophene-2,5-dicarboxyester as a starting material, Potassium peroxodisulfate and iron sulfate and 3,4-ethylenedioxythiophene obtained above are introduced into polystyrene sulfonic acid aqueous solution and reacted to polythiophene such as poly (3,4-ethylenedioxythiophene) and polystyrene. A composition in which polyanions such as sulfonic acid are complexed can be obtained.

  In the present invention, the acrylic resin (B) having an alkyl chain having 12 to 25 carbon atoms used for the laminated film of the laminated polyester film is, for example, an acrylic having an alkyl group having 12 to 25 carbon atoms in the side chain. And a copolymerized acrylic resin of a monomer and a monomer copolymerizable with the acrylic monomer.

  The copolymerization ratio of the acrylic monomer having an alkyl group having 12 to 25 carbon atoms in the side chain in the copolymerized acrylic resin is preferably 35% by weight or more. The amount of copolymerization is more preferably 35 to 85% by weight, and most preferably 60 to 80% by weight in terms of releasability and copolymerization.

  The acrylic monomer having an alkyl chain having 12 to 25 carbon atoms in the side chain is not particularly limited as long as it satisfies the above requirements. For example, dodecyl acrylate, tridecyl acrylate , Tetradecyl acrylate, pentadecyl acrylate, hexadecyl acrylate, heptadecyl acrylate, octadecyl acrylate, nonadecyl acrylate, eicosyl acrylate, henecosyl acrylate, docosyl acrylate, tricosyl acrylate, tetracosyl acrylate, pentacosyl acrylate, methacrylic acid Long-chain alkyl group-containing acrylic monomers such as dodecyl acid, eicosyl methacrylate, and pentacosyl tacrylate are preferably used. In addition, about what has more than 25 carbon atoms, it is difficult to obtain industrially easily, and the thing with about 25 carbon atoms is an upper limit.

  The long-chain alkyl group-containing acrylic resin used in the present invention is preferably an aqueous coating material from the viewpoint of the environment. For example, in order to emulsify, other copolymerizable monomers include: Acrylic monomers and vinyl monomers can be used. As monomers, acrylic acid, methacrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethoxyethyl acrylate, 2-methoxyethyl acrylate, 2-butoxyethyl acrylate, methyl methacrylate, ethyl methacrylate , Acrylonitrile, methacrylonitrile, vinyl acetate, (meth) acrylic acid, styrene, itaconic acid, (meth) acrylamide, 2-hydroxyethyl (meth) acrylate, diethylene glycol mono (meth) acrylate, N-methylol (meth) acrylamide, Dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, (meth) acryloyloxyethyl phosphate ester, sodium vinyl sulfonate, sodium styrene sulfonate, and maleic anhydride Or the like can be used acid.

  Preferable long chain alkyl group-containing acrylic resins include a copolymer selected from stearyl methacrylate, behenyl methacrylate, behenyl acrylate, 2-hydroxyethyl methacrylate, methacrylic acid, acrylic acid, and methyl methacrylate.

  In the present invention, the epoxy crosslinking agent and / or the reaction product (C) that can be used for the laminated film of the laminated polyester film is not particularly limited, but in the present invention, the molecular weight is preferably 1000 or less. is there. In particular, by making the epoxy-based crosslinking agent and / or its reaction product (C) water-soluble and having a molecular weight of 1000 or less, flexibility and fluidity in the stretching process are expressed, and the mixture that forms the laminated film The stretchable followability after drying is enhanced, the whitening phenomenon due to cracks in the coating film is suppressed, and transparency is imparted. On the other hand, for example, if the molecular weight is too large, a phenomenon such as cracking of the coating film occurs during stretching after coating and drying, and the transparency tends to decrease. Further, by setting the molecular weight to 800 or less, more preferably 600 or less, the composition (A), the long-chain alkyl group-containing acrylic resin (B), the epoxy-based crosslinking agent and / or the reaction product (C) thereof. However, compatibility becomes easier and transparency is improved.

  In the present invention, the epoxy-based cross-linking agent and / or the reaction product (C) thereof is preferably a water-soluble cross-linking agent since transparency and conductivity are improved.

  In the present invention, the water-soluble cross-linking agent means a cross-linking agent having a water content of preferably 80% or more, and the “water content” means 90 parts of a solid content of the cross-linking agent at a temperature of 23 ° C. When dissolved in water, it refers to the proportion of the crosslinking agent dissolved. That is, when the water content is 80%, 80% by weight of 10 parts of the crosslinking agent is dissolved in 90 parts of water at a temperature of 23 ° C., and the remaining 20% by weight of the crosslinking agent remains as an undissolved product. Indicates the state. Further, 100% water content represents a state in which 10 parts of the crosslinking agent used are all dissolved in 90 parts of water. In the present invention, the epoxy crosslinking agent and / or the reaction product (C) thereof preferably has a water content of 90% or more, more preferably a water content of 100%. When the water solubility is high, not only the coating liquid itself can be made water-based but also excellent in terms of transparency and conductivity.

  The epoxy-based crosslinking agent and / or reaction product (C) described above, for example, does not block compared to the addition of a high-boiling solvent such as glycerin, and does not cause contamination inside the tenter that performs the heat treatment process or air pollution. It is preferable because it is not present.

  In the laminated polyester film of the present invention, the type of epoxy-based crosslinking agent and / or reaction product (C) thereof is not particularly limited. For example, sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, diglycerol polyglycidyl ether System, polyethylene glycol diglycidyl ether system and the like can be used. For example, the epoxy compound “Denacol” (registered trademark) manufactured by Nagase Chemtech Co., Ltd. (EX-611, EX-614, EX-614B, EX-512, EX-521, EX-421, EX-313, EX-810, EX-830, EX-850, etc.), diepoxy-polyepoxy compounds (SR-EG, SR-8EG, SR-GLG, etc.) manufactured by Sakamoto Yakuhin Kogyo Co., Ltd., epoxy crosslinking agent “EPICLON” manufactured by Dainippon Ink Industries, Ltd. (Registered trademark) EM-85-75W, CR-5L, or the like can be suitably used. Among them, those having water solubility are preferable.

  The epoxy-based crosslinking agent and / or reaction product (C) thereof preferably has an epoxy equivalent weight of 100 to 300 WPE in terms of reactivity, and more preferably has an epoxy equivalent of 110 to 200 WPE. is there.

  In the present invention, the coating liquid used in the production of the laminated film of the laminated polyester film is preferably an aqueous coating liquid containing water as a main medium. The coating liquid suitably used in the present invention may contain an appropriate amount of an organic solvent to the extent that the effects of the present invention are not impaired for the purpose of improving the coating property and improving the transparency, for example, isopropyl alcohol. , T-butyl cellosolve, n-butyl cellosolve, ethyl cellosolve, acetone, N-methyl-2-pyrrolidone, ethanol, and methanol can be preferably used. Especially, it is especially preferable to use isopropyl alcohol from the point which improves applicability | paintability, The content is 20 weight% or less in a coating liquid, More preferably, it is 10 weight% or less. If a large amount of an organic solvent is contained in the coating liquid, there is a risk of explosion in a tenter that performs preheating, drying, stretching, heat treatment, and the like when applied to a so-called in-line coating method.

  In the state of the laminated film, the epoxy-based crosslinking agent and / or reaction product (C) used in the present invention may be in a state of being bonded to a functional group contained in a component constituting the laminated film, It may be in an unreacted state or partially formed with a crosslinked structure. In the state of the laminated film, the epoxy-based crosslinking agent and / or reaction product (C) thereof is preferably crosslinked in terms of coating strength, blocking resistance, stickiness, and water resistance. . The crosslinking may be in a state of being bonded to a functional group contained in another component, or may be a self-crosslinking structure of the crosslinking agent itself.

  In the present invention, a combination of a plurality of crosslinking agents is also preferably used. For example, a combination of an epoxy crosslinking agent and a melamine crosslinking agent, or a combination of different types of epoxy crosslinking agents exhibits the characteristics of both. This is a preferred embodiment. Examples of the crosslinking agent used at this time include melamine crosslinking agents, epoxy crosslinking agents, aziridine crosslinking agents, amide epoxy compounds, titanate coupling agents such as titanium chelates, oxazoline crosslinking agents, isocyanate crosslinking agents, A methylolated or alkylolated urea system, an acrylamide system, or the like can be used.

  In the present invention, the laminated film of the laminated polyester film comprises an epoxy-based crosslinking agent and a composition (A) and an epoxy crosslinking agent and / or a reaction product (C) in a weight ratio of solids in the laminated film. It is preferable that the reaction product (C) is 50 to 95% by weight. For example, if the epoxy-based cross-linking agent and / or the reaction product (C) thereof is less than 50% by weight, conductivity may be difficult to develop. Furthermore, when the amount of the epoxy-based crosslinking agent and / or its reaction product (C) is extremely small, for example, less than 10% by weight, the insulation level is the same as that of an untreated polyester film, and the coating film The whitening is large and the transparency is poor. On the other hand, when the epoxy crosslinking agent and / or its reaction product (C) exceeds 95% by weight, the transparency is improved, but the amount of the composition (A) contributing to the conductivity is too small, and the conductivity is low. It becomes difficult to express. According to the study by the present inventors, the epoxy-based crosslinking agent and / or the reaction product (C) thereof is more preferably 50 to 80% by weight from the viewpoint of transparency and conductivity, and further preferably. Is 60 to 80% by weight. By setting the content of the epoxy-based crosslinking agent and / or the reaction product (C) thereof in the laminated film to 50 to 90% by weight, it becomes possible to achieve both transparency and conductivity at a very high level. .

  On the other hand, in the present invention, the laminated film of the laminated polyester film has an alkyl chain having 12 to 25 carbon atoms in addition to the composition (A) and the epoxy-based crosslinking agent and / or the reaction product (C). It is necessary that the acrylic resin (B) is contained, and 5 parts by weight or more with respect to 100 parts by weight in total of the composition (A) and the epoxy-based crosslinking agent and / or reaction product (C) thereof. By adding, releasability is expressed, but by adding further 10 to 40 parts by weight, extremely high releasability can be imparted. More preferably, by setting the content to 15 to 30% by weight, not only can a high level of releasability be imparted, but also the oligomer precipitation inhibiting property during heating can be made to a very high level. This is because a polythiophene-based composition (A), an epoxy-based cross-linking agent and / or a reaction product (C) thereof having hydrophilicity, that is, a substance having a high surface energy, and having 12 to 25 carbon atoms. It is presumed to be due to a phase separation phenomenon between a hydrophobic compound such as an acrylic resin (B) having an alkyl chain, that is, a substance having a low surface energy. In particular, it is estimated that this phenomenon appears more prominently when applied to a process capable of heat treatment at a high temperature such as an in-line coating method.

  In the present invention, the laminated film of the laminated polyester film comprises the composition (A) and an acrylic resin (B) having an alkyl chain having 12 to 25 carbon atoms as essential components, and further an epoxy crosslinking agent and / or reaction thereof. Although it is preferable that the product (C) is contained, at least one other resin, particularly a polyester resin, a urethane resin, and an acrylic resin may be further contained. However, for example, when other resin components such as a polyester resin exceed 20% by weight, the characteristics of the present invention, in particular, the releasability tends to be hardly exhibited. When added, the content is preferably 10% by weight or less. More preferably, the content is 5% by weight or less.

  Furthermore, in this invention, you may provide the layer which consists of at least 1 sort (s) chosen from the polyester resin, the urethane resin, and the crylic resin in the surface on the opposite side to the laminated film provided in at least one side of the polyester film. In this case, the side on which the laminated film is provided has a high level of conductivity, release properties, water resistance, smoothness, and oligomer precipitation suppression without humidity dependence, and the opposite side has adhesion and the like. For example, it is very useful when used in a laminated structure such as a transfer foil application.

  The polyester resin, urethane resin, and acrylic resin used here may be the same as or different from the resin group that can be arbitrarily used in the laminated film. For example, the following are used. be able to.

  In the present invention, a polyester resin that can be suitably used as a constituent of a laminated film of a laminated polyester film or a layer on the opposite side has an ester bond in the main chain or side chain, and is obtained by polycondensation of a dicarboxylic acid and a diol. Is obtained.

  As the carboxylic acid component constituting the polyester resin, aromatic, aliphatic, and alicyclic dicarboxylic acids and trivalent or higher polyvalent carboxylic acids can be used.

  As aromatic dicarboxylic acids, terephthalic acid, isophthalic acid, orthophthalic acid, phthalic acid, 2,5-dimethylterephthalic acid, 1,4-naphthalenedicarboxylic acid, biphenyldicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,2 -Bisphenoxyethane-p, p'-dicarboxylic acid, phenylindanedicarboxylic acid, and the like can be used. From the viewpoint of the strength and heat resistance of the laminated film, these aromatic dicarboxylic acids are preferably polyesters that occupy 30 mol% or more, more preferably 35 mol% or more, and most preferably 40 mol% or more of the total dicarboxylic acid component. It is preferable to use it.

  Examples of the aliphatic and alicyclic dicarboxylic acids include succinic acid, adipic acid, sebacic acid, azelaic acid, dodecanedioic acid, dimer acid, 1,3-cyclopentanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid and the like, and ester-forming derivatives thereof can be used.

  As the glycol component of the polyester resin, ethylene glycol, diethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 2,4-dimethyl-2-ethylhexane-1,3- Diol, neopentyl glycol, 2-ethyl-2-butyl-1,3-propanediol, 2-ethyl-2-isobutyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2,2 , 4-Trimethyl-1,6-hexanediol, 1,2-si Rhohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, 4,4'-thiodiphenol, bisphenol A 4,4′-methylenediphenol, 4,4 ′-(2-norbornylidene) diphenol, 4,4′-dihydroxybiphenol, o-, m-, and p-dihydroxybenzene, 4,4′-isopropylidene Phenol, 4,4′-isopropylidene bin diol, cyclopentane-1,2-diol, cyclohexane-1,2-diol, cyclohexane-1,4-diol and the like can be used.

  When the polyester resin is used as an aqueous coating liquid, it is preferable to copolymerize a compound containing a sulfonate group or a compound containing a carboxylate group in order to facilitate water-solubilization or water-dispersion of the polyester resin. .

  Examples of the compound containing a carboxylate group include trimellitic acid, trimellitic anhydride, pyromellitic acid, pyromellitic anhydride, 4-methylcyclohexene-1,2,3-tricarboxylic acid, trimesic acid, 1,2, 3,4-butanetetracarboxylic acid, 1,2,3,4-pentanetetracarboxylic acid, 3,3 ′, 4,4′-benzophenonetetracarboxylic acid, 5- (2,5-dioxotetrahydrofurfuryl) -3-methyl-3-cyclohexene-1,2-dicarboxylic acid, 5- (2,5-dioxotetrahydrofurfuryl) -3-cyclohexene-1,2-dicarboxylic acid, cyclopentanetetracarboxylic acid, 2,3 , 6,7-Naphthalenetetracarboxylic acid, 1,2,5,6-naphthalenetetracarboxylic acid, ethylene glycol bis trimellitate 2,2 ′, 3,3′-diphenyltetracarboxylic acid, thiophene-2,3,4,5-tetracarboxylic acid, ethylenetetracarboxylic acid, etc., or alkali metal salts, alkaline earth metal salts, ammonium salts thereof However, it is not limited to these.

  Examples of the compound containing a sulfonate group include sulfoterephthalic acid, 5-sulfoisophthalic acid, 4-sulfoisophthalic acid, 4-sulfonaphthalene-2,7-dicarboxylic acid, sulfo-p-xylylene glycol, 2-sulfo -1,4-bis (hydroxyethoxy) benzene or the like, or alkali metal salts, alkaline earth metal salts, and ammonium salts thereof can be used, but the present invention is not limited thereto.

  Preferred polyester resins include terephthalic acid, isophthalic acid, sebacic acid, 5-sodium sulfoisophthalic acid as the acid component, and a copolymer selected from ethylene glycol, diethylene glycol, 1,4-butanediol, and neopentyl glycol as the glycol component. Is mentioned. When water resistance is required, a copolymer having trimellitic acid as its copolymer component can be suitably used instead of 5-sodium sulfoisophthalic acid.

  The glass transition point (hereinafter abbreviated as “Tg”) of the polyester resin is preferably 0 to 130 ° C., more preferably 10 to 85 ° C. When Tg is less than 0 ° C., for example, a blocking phenomenon may occur where the laminated films adhere to each other, and when Tg exceeds 130 ° C., the stability and water dispersibility of the resin may be inferior.

  Furthermore, various additives such as antioxidants, heat stabilizers, weather stabilizers, ultraviolet absorbers, organic lubricants, pigments, dyes, organics are used in the laminated film as long as the effects of the present invention are not impaired. Alternatively, inorganic fine particles, fillers, antistatic agents, nucleating agents, and the like may be blended.

  In particular, when the present invention is carried out, those obtained by adding and blending inorganic particles in the coating liquid and biaxially stretching are more preferable because the lubricity is improved.

  As inorganic particles to be added, typically, silica, colloidal silica, alumina, alumina sol, kaolin, talc, mica, calcium carbonate, and the like can be used. The inorganic particles used may be in a range that does not impair the effects of the present invention. For example, the optical film used in a laminated state as a member or its protective film is peeled off from the transfer film of the present invention. Since the smoothness and glossiness of the member surface after the peeling are very important, such as when the surface roughness of the transfer film, the three-dimensional centerline average roughness (SRa) is 3 to 20 nm It is preferable. Furthermore, in the present invention, SRa is more preferably 3 to 18 nm. The three-dimensional ten-point average roughness (SRz) is preferably 1000 nm or less, more preferably 800 nm or less. If SRa and SRz exceed the above ranges, the surface of the optical resin is partially rough and tends to deteriorate transparency.

  In order to achieve the above, in the present invention, the particles to be added are preferably those having an average particle diameter of 0.01 to 0.3 μm, more preferably 0.02 to 0.2 μm, and the mixing ratio with respect to the solid content Although not particularly limited, the weight ratio is preferably 0.05 to 20 parts by weight, more preferably 0.1 to 10 parts by weight.

Further, it is necessary that the number of internal foreign matters of 100 μm or more in the laminated polyester film is 10 pieces / m ² or less, and preferably 5 pieces / m ² or less.

  The presence of internal foreign matter in the laminated polyester film is not preferable because the obtained optical resin film has many bright spot defects and causes display defects when incorporated into a liquid crystal display device or the like.

  In order to obtain such a polyester film, it is necessary to use a filter having a filtration accuracy of 1 to 20 μm. In order to suppress the generation of filtration life, coarse protrusions and internal foreign matters, a filter having an absolute filtration accuracy of 3 to 10 μm is required. More preferably, it is used.

  In carrying out the present invention, for example, a reverse coating method, a spray coating method, a bar coating method, a gravure coating method, a rod coating method, a die coating method, or the like can be used as a method for applying an aqueous resin.

  Although the thickness of a laminated film is not specifically limited, Usually, the range of 0.005-0.2 micrometer is preferable, More preferably, it is 0.01-0.1 micrometer, Most preferably, it is 0.01 micrometer-0.05 micrometer. If the thickness of the laminated film is too thin, an antistatic property may be deteriorated.

  In producing the laminated polyester film according to the present invention, the preferred method for providing the laminated film is the method of applying during the production process of the polyester film as the base film and stretching with the base film. . For example, the melt-extruded polyester film before crystal orientation is stretched about 2.5 to 5 times in the longitudinal direction, and the coating liquid is continuously applied to the uniaxially stretched polyester film. The applied polyester film is dried while passing through a zone heated stepwise, and is stretched about 2.5 to 5 times in the width direction. Further, it can be obtained by a method (in-line coating method) in which the crystal orientation is continuously led to a heating zone having a temperature of 150 to 250 ° C. The coating solution used in this case is preferably a water-based one in terms of environmental pollution and explosion resistance.

  In the present invention, before applying the coating liquid, the surface of the polyester film as the base film (in the above example, uniaxially stretched polyester film) is subjected to corona discharge treatment, etc., and the wetting tension of the surface is preferably 47 mN / m or more, more preferably 50 mN / m or more can be preferably used because it can improve the adhesion to the polyester film that is the base film of the laminated film. It is also preferable to improve the wettability and the adhesion to the substrate film by adding a slight amount of an organic solvent such as isopropyl alcohol, butyl cellosolve and N-methyl-2-pyrrolidone in the coating liquid.

  Examples of the optical resin for solution film formation in the present invention include polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate and polybutylene terephthalate, alicyclic polyolefins, polyarylate, polycarbonate, polyethersulfone, and polysulfone. Preferred are alicyclic polyolefin, polyarylate, polycarbonate, polyethersulfone and polysulfone, and more preferred are polycarbonate and alicyclic polyolefin in terms of optical properties.

  Specific examples of the alicyclic polyolefin include a polymer having a structural unit represented by the following chemical formula (3) and / or chemical formula (4).

(In the formula, R1, R2, R3, and R4 are hydrogen, a hydrocarbon residue having 1 to 6 carbon atoms, or a polar group such as halogen, ester, nitrile, pyridyl, and may be the same or different, R1, R2 and R3, R4 may form a ring with each other, m is a positive integer, and n, q are 0 or a positive integer.)

(In the formula, R5, R6, R7, and R8 are hydrogen, a hydrocarbon residue having 1 to 6 carbon atoms, or a polar group such as halogen, ester, nitrile, and pyridyl, which may be the same or different, R5, R6 and R7, R8 may form a ring with each other, k is a positive integer, and l, p are 0 or a positive integer.)
Examples of the monomer used in the polymer having the structural unit represented by the chemical formula (3) include norbornene and alkyl and / or alkylidene substituted products thereof (for example, 5-methyl-2-norbornene, 5, 6 Dimethyl-2-norbornene, 5-ethyl-2-norbornene, 5-butyl-2-norbornene, 5-ethylidene-2-norbornene, etc.), dicyclopentadiene, 2,3-dihydrodicyclopentadiene, their methyl, ethyl Alkyl substituents such as propyl, butyl and the like, and polar group substituents such as halogen (eg dimethanooctahydronaphthalene, its alkyl and / or alkylidene substitutes), and halogen isopolar group substitutes (eg 6-methyl -1,4: 5,8-dimethano-1,4,4a, 5,6,7,8 8a-octahydronaphthalene, 6-ethyl-1,4: 5,8-dimethano 1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-ethylidene-1,4: 5,8 Dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-chloro-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8 , 8a-octahydronaphthalene, 6-cyano-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-pyridyl-1,4: 5 , 8-Dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene and 6-methoxycarbonyl-1,4: 5,8-dimethano-1,4,4a, 5,6 , 7,8,8a-octahydronaphthalene, etc.), cyclopentadiene ˜tetramer (eg, 4,9: 5,8-dimethano-3a, 4,4a, 5,8,8a, 9,9a-octahydro-1H-benzoindene, 4,11: 5,10: 6 9-trimethano-3a, 4,4a, 5,5a, 6,9,9a, 10,10a, 11,11a-dodecahydro-1H-cyclopentanthracene, etc.), one or more of these. And polymerized by a known ring-opening polymerization method to obtain a ring-opened polymer. The obtained ring-opening polymer is hydrogenated by an ordinary hydrogenation method to produce a polymer having a structural unit represented by the above chemical formula (3).

  The glass transition temperature of the polymer is preferably 160 ° C. or higher. For this purpose, tetramer or pentamer of norbornene-based monomers are used, or these are used as a main component and bicyclic or 3 It is preferable to use in combination with a monomer of a ring. In particular, from the viewpoint of birefringence, it is preferable to use a tetrameric lower alkyl-substituted product or alkenyl-substituted product as a main component.

  In addition, examples of the monomer used in the polymer having the structural unit represented by the chemical formula (4) include one or more of the norbornene monomers and ethylene, which are subjected to addition polymerization by a known method. To obtain a polymer. The obtained polymer and / or hydrogenated product thereof is used as a polymer having a structural unit represented by the above chemical formula (4), and they are all saturated polymers.

  The alicyclic polyolefin is prepared by adding an α-olefin such as 1-butene, 1-pentene and 1-hexene as a molecular weight regulator in the production process of the structural unit represented by the chemical formula (3) or (4). Or a polymer obtained by copolymerizing a small amount of other monomer components such as cycloolefin such as cyclopropene, cyclobutene, cyclopentene, cycloheptene, cyclooctene and 5,6-dihydrocyclopentadiene.

  Examples of the alicyclic polyolefin include “Arton” (registered trademark) of JSR Corporation, “ZEONOR” (registered trademark) and “ZEONEX” (registered trademark) of Nippon Zeon Corporation, and Mitsui Chemicals, Inc. “Apel” (registered trademark) is preferably used.

  The molecular weight range of these alicyclic polyolefins is preferably 1 to 300,000 in terms of strength, and the number average molecular weight measured by GPC (gel permeation chromatography) analysis using cyclohexane as a solvent. Preferably it is 2 to 200,000.

  Further, when the unsaturated bond remaining in the molecular chain of the alicyclic polyolefin is saturated by hydrogenation (hereinafter referred to as hydrogenation), the hydrogenation rate is preferably 90% or more, more preferably 95% or more. More preferably, it is 99% or more. By being a saturated polymer, weather resistance and light deterioration resistance are improved.

  Only 1 type may be used for the alicyclic polyolefin used by this invention, and 2 or more types may be used for it. Moreover, you may blend the thing from which molecular weight differs also in the same seed | species. Further, an antioxidant, an antistatic agent, a lubricant, a surfactant, an ultraviolet absorber, and the like may be added to the alicyclic polyolefin used in the present invention.

  Next, a method for producing a polyester film used in the present invention will be described in more detail with respect to an example in which polyethylene terephthalate (hereinafter abbreviated as “PET”) is used as a base film, but the method is not limited thereto. Absent.

  The manufacturing method of the laminated polyester film used by this invention is illustrated and demonstrated more concretely. PET pellets having an intrinsic viscosity of 0.5 to 0.8 dl / g are vacuum-dried and then supplied to an extruder and melted at a temperature of 260 to 300 ° C. At this time, it is preferable to use a filter having an absolute filtration accuracy of 3 to 10 μm. Then, it extrudes in a sheet form from a T-shaped base, is wound around a mirror surface casting drum having a surface temperature of 10 to 60 ° C. using an electrostatic application casting method, and is cooled and solidified to produce an unstretched PET film. This unstretched film is stretched 2.5 to 5 times in the machine direction (film traveling direction) between rolls heated to a temperature of 70 to 120 ° C. At least one surface of the film is subjected to corona discharge treatment, the surface has a wetting tension of 47 mN / m or more, and the aqueous coating liquid according to the present invention is applied to the treated surface. The coated film is held by a clip, guided to a hot air zone heated to 70 to 150 ° C., dried, stretched 2.5 to 5 times in the width direction, and subsequently a heat treatment zone having a temperature of 160 to 250 ° C. Then, heat treatment is performed for 1 to 30 seconds to complete crystal orientation. During this heat treatment step, a relaxation treatment of 1 to 10% may be performed in the width direction or the longitudinal direction as necessary. Biaxial stretching may be either longitudinal, transverse sequential stretching, or simultaneous biaxial stretching, and may be re-stretched in either the longitudinal or transverse direction after longitudinal and transverse stretching. Moreover, although the thickness of a polyester film is not specifically limited, 1-500 micrometers is preferable.

  By adding at least one substance selected from a laminated film forming composition or a reaction product of the laminated film forming composition to a polyester film that is a base film on which the laminated film is provided, Adhesiveness with the polyester film which is a base film can be improved, or slipperiness can be improved. The total amount of the laminated film forming composition or these reaction products is preferably 5 ppm or more and less than 20% by weight from the viewpoint of adhesion and slipperiness. In particular, when environmental protection and productivity are taken into consideration, a method using recycled pellets containing the laminated film forming composition is suitable.

  The laminated polyester film of the present invention thus obtained is excellent in releasability and surface properties and has few bright spot defects, so that it is used as a process film for solution casting of optical resins such as polycarbonate and alicyclic polyolefin. It can be suitably used as a substrate film for the transfer foil used.

[Characteristic measurement method and effect evaluation method]
The characteristic measuring method and the effect evaluating method in the present invention are as follows.

(1) Thickness of laminated film A cross section of a sample, for example, a laminated polyester film, is cut into ultrathin sections, and stained with RuO4 dye, OsO4 dye, or both dyed ultrathin sections by TEM (transmission electron microscope). Observation and photography were performed. The thickness of the laminated film was measured from the cross-sectional photograph.
[Observation method]
-Apparatus: Transmission electron microscope (H-7100FA type, manufactured by Hitachi, Ltd.)
・ Measurement conditions: Acceleration voltage 100kV
・ Sample preparation: Ultrathin section method.

(2) Surface Roughness Three-dimensional centerline average roughness (SRa) and three-dimensional ten-point average roughness (SRz) are obtained by using an optical stylus type three-dimensional roughness meter ET-30HK (manufactured by Kosaka Laboratory Ltd.). It was measured at a measurement length of 0.5 mm, a measurement number of 80, a cutoff of 0.25 mm, a feed pitch of 5 μm, a stylus load of 10 mg, and a speed of 100 μm / sec.

(3) Internal foreign matter of the film The bright spot portion confirmed by visual observation of the film under the crossed Nicols of the polarizing plate is observed with a microscope, the size of the core portion of the foreign matter is measured, and foreign matter having a size of 100 μm or more is measured. Count. The measurement area is 1 m ² .

(4) Releasability On the obtained polyester film, a methylene chloride solution prepared by dissolving alicyclic polyolefin (JSR Corp. Arton G) as an optical resin to a concentration of 20% by weight is applied by a die coating method. Thereafter, it was passed through an oven and dried at a temperature of 40 ° C. for 3 minutes, and then peeled from the polyester film to obtain a thermoplastic resin film. The presence or absence of a peel-off on the surface of the peeled thermoplastic resin film and polyester film was observed. In both cases, the case where there was no peel-off was marked with ◯, and the case where there was no peel-off.

(5) Bright spot defect The optical resin film obtained by the above method was observed for defects that became bright spots that could be visually confirmed by reflection of a three-wavelength fluorescent lamp in a dark room, and the number was counted. The measurement area is 1 m ² .

(6) Haze (transparency)
According to JIS-K-7105 (1981), the haze of the thermoplastic resin film obtained by the above method was measured.

Next, the present invention will be described based on examples.
Example 1
PET pellets (extreme viscosity 0.63 dl / g) substantially free of particles are sufficiently dried in vacuum, then supplied to an extruder and melted at a temperature of 285 ° C. The sheet was extruded from a die die into a sheet shape, wound around a mirror casting drum having a surface temperature of 25 ° C. using an electrostatic application casting method, and cooled and solidified. The unstretched PET film thus obtained was heated to a temperature of 92 ° C. and stretched 3.3 times in the longitudinal direction to obtain a uniaxially stretched PET film. The uniaxially stretched PET film was subjected to corona discharge treatment in air, its wetting tension was 55 mN / m, and the following laminated film forming coating solution was applied to the treated surface. 2. A uniaxially stretched PET film coated with a laminated film forming coating solution is guided to a preheating zone while being gripped with a clip, dried at a temperature of 95 ° C., and then continuously in a heating zone at a temperature of 100 ° C. in the width direction. The film was stretched 5 times and further subjected to heat treatment in a heating zone at a temperature of 225 ° C. to obtain a laminated PET film in which crystal orientation was completed. The thickness of the obtained laminated PET film was 38 μm, and the thickness of the laminated film was 0.025 μm. The results are shown in Table 1. It was excellent in releasability, transparency and bright spot defects.
"Laminated film forming coating solution"
-Liquid A1:
An aqueous coating solution of a composite composed of poly-3,4-ethylenedioxythiophene / polystyrene sulfonic acid (“Baytron” (registered trademark) P manufactured by Bayer / HC Starck (Germany)).
-Coating liquid B1:
As an epoxy crosslinking agent, a polyglycerol polyglycidyl ether type epoxy crosslinking agent (“Denacol” (registered trademark) EX-512 (manufactured by Nagase ChemteX Corporation) EX-512 (molecular weight: about 630, epoxy equivalent: 168, water solubility: 100%)) in water Dissolved aqueous coating solution.
・ Coating liquid C1:
An aqueous coating solution in which a long-chain alkyl group-containing acrylic resin having the following copolymer composition is dissolved in water containing 5% by weight of isopropyl alcohol and 5% by weight of n-butyl cellosolve.
<Copolymerization component>
65% by weight of behenyl methacrylate
(Long chain alkyl chain carbon number 22)
Methacrylic acid 25% by weight
2-hydroxyethyl methacrylate 10% by weight
A mixture of the above coating liquid A1 and coating liquid B1 at a solid content weight ratio of coating liquid A1 / coating liquid B1 = 20/80 was aged at room temperature for 5 days (abbreviated as aging coating liquid 1). . Thereafter, a solution obtained by mixing the aging coating liquid 1 and the coating liquid C3 in a solid weight ratio at an aging coating liquid 1 / coating liquid C3 = 100/20 was used as a laminated film forming coating liquid.

(Example 2)
A laminated PET film was obtained in the same manner as in Example 1 except that the following laminated film forming coating solution was used instead of the laminated film forming coating solution used in Example 1.
"Laminated film forming coating solution"
The same coating liquid A1 and coating liquid B1 as in Example 1 were used.
・ Coating liquid C2:
An aqueous coating solution in which a long-chain alkyl group-containing acrylic resin having the following copolymer composition is dissolved in water containing 5% by weight of isopropyl alcohol and 5% by weight of n-butyl cellosolve.
<Copolymerization component>
Stearyl methacrylate 65% by weight
(Long chain alkyl chain carbon number 12)
Methacrylic acid 25% by weight
2-hydroxyethyl methacrylate 10% by weight
A mixture of the above coating liquid A1 and coating liquid B1 at a solid content weight ratio of coating liquid A1 / coating liquid B1 = 20/80 was aged at room temperature for 5 days (abbreviated as aging coating liquid 1). . Thereafter, a solution obtained by mixing the aging coating liquid 1 and the coating liquid C2 in a weight ratio of the aging coating liquid 1 / coating liquid C2 = 100/5 was used as a laminated film forming coating liquid. The results are shown in Table 1. It was excellent in releasability, transparency and bright spot defects.

(Example 3)
As PET pellets used in Example 1, PET pellets containing 0.015% agglomerated silica having an average particle diameter of 0.4 μm and 0.005% agglomerated silica having an average particle diameter of 1.5 μm (with an intrinsic viscosity of 0.63 dl / A laminated PET film was obtained in the same manner as in Example 1 except that g) was used, the following laminated film forming coating solution was used, and the thickness of the PET film was 16 μm. The results are shown in Table 1. It was excellent in releasability, transparency and bright spot defects.
"Laminated film forming coating solution"
The same coating liquid A1 and coating liquid B1 as in Example 1 were used.
-Coating liquid C3:
An aqueous coating solution obtained by dissolving a long-chain alkyl group-containing acrylic resin having the following copolymer composition in water containing 10% by weight of isopropyl alcohol and 5% by weight of n-butyl cellosolve.
<Copolymerization component>
65% by weight of behenyl methacrylate
(Long chain alkyl chain carbon number 22)
Methacrylic acid 25% by weight
2-hydroxyethyl methacrylate 10% by weight
A mixture of the above coating liquid A1 and coating liquid B1 at a solid content weight ratio of coating liquid A1 / coating liquid B1 = 25/75 was aged at room temperature for 5 days (abbreviated as aging coating liquid 1). . Thereafter, a solution obtained by mixing the aged coating solution 1 and the coating solution C3 in a solid weight ratio at an aged coating solution 1 / coating solution C3 = 100/5 was used as a laminated film forming coating solution.

(Comparative Example 1)
PET pellets (intrinsic viscosity 0.63 dl / g) containing 0.015% aggregated silica with an average particle size of 0.4 μm and 0.005% aggregated silica with an average particle size of 1.5 μm were sufficiently vacuum dried, A laminated PET film was obtained in the same manner as in Example 1 except that it was supplied to an extruder, melted at a temperature of 285 ° C., and filtered through a filter having an absolute filtration accuracy of 15 μm. The results are shown in Table 1. It was inferior in brightness point defect and transparency.

(Comparative Example 2)
A laminated PET film was prepared in the same manner as in Example 1 except that the following laminated film forming coating liquid was used instead of the laminated film forming coating liquid used in Example 1, and the thickness of the coating layer was 0.08 μm. Got. The results are shown in Table 1. It was inferior to releasability.
"Laminated film forming coating solution"
-Coating liquid D1:
An aqueous coating solution obtained by dissolving polystyrene sulfonate ammonium salt (weight average molecular weight: 65000) in water.
・ Coating liquid E1:
An aqueous coating liquid (emulsion particle diameter is 50 nm) in which an acrylic resin (glass transition temperature: 42 ° C.) having the following copolymer composition is dispersed in water in the form of particles.
<Copolymerization component>
62% by weight methyl methacrylate
(C1 of alkyl chain)
Ethyl acrylate 35% by weight
(Alkyl chain carbon number 2)
Acrylic acid 2% by weight
N-methylolacrylamide 1% by weight
The above-described coating liquid D1 and coating liquid E1 were mixed at a solid content weight ratio of coating liquid D1 / coating liquid E1 = 20/80 to obtain a laminated film forming coating liquid.

  The biaxially stretched polyester film for optical resin solution film formation according to the present invention is useful because it can be used for solution film formation of polycarbonate, alicyclic polyolefin and the like.

Claims (5)

A laminated polyester film in which a laminated film comprising a composition (A) and an acrylic resin (B) having an alkyl chain having 12 to 25 carbon atoms is provided on at least one side of a polyester film, the composition (A ) Is a composition comprising polythiophene and polyanion and / or a composition comprising polythiophene derivative and polyanion, and the number of internal foreign matters having a particle size of 100 μm or more contained in the laminated polyester film is 10 / m ^2. A laminated polyester film for forming an optical resin solution, which is less than   The optical film according to claim 1, wherein the polyester film has a three-dimensional centerline average roughness (SRa) of 3 to 20 nm and a three-dimensional ten-point average roughness (SRz) of 1000 nm or less. Laminated polyester film for resin solution casting.   The laminated film further contains an epoxy-based crosslinking agent and / or a reaction product (C) thereof, and is an epoxy-based crosslinking agent and / or its composition with respect to the composition (A) in a solid weight ratio. 3. The laminated polyester film for forming an optical resin solution according to claim 1, wherein the total amount of the reaction product (C) is 50 to 95% by weight.   In the laminated film, the acrylic resin (B) having an alkyl chain having 12 to 25 carbon atoms is added in a total of 100 parts by weight of the composition (A) and the epoxy crosslinking agent and / or reaction product (C) thereof. The laminated polyester film for optical resin solution film-forming according to any one of claims 1 to 3, wherein 10 to 40 parts by weight are contained.   The laminated polyester film for optical resin solution film formation according to any one of claims 1 to 4, which is used for solution film formation of polycarbonate or alicyclic polyolefin.