JP2006264320A - Biaxial stretching polyester film for solution system film casting of optical resin - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a biaxial stretching polyester film for solution system film casting of an optical resin, which affords excellent planarity and transparency of an optical resin film and is excellent in handling performance. <P>SOLUTION: The biaxial stretching polyester film for solution system film casting is provided with a resin layer, whose weight ratio of a polystyrene sulfonic acid and/or its salt and a polyester resin ranging from 1/99 to 50/50, on at least one side of the polyester film. The polyester resin has 2-15 mole% of a co-polyrmerized monomer bearing sulfonic acid group and/or its salt. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a biaxially stretched polyester film for forming an optical resin solution, and more specifically, an optical resin excellent in flatness and transparency of a film using an optical resin and excellent in handling properties. The present invention relates to a biaxially stretched 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 polymers, polycarbonates and alicyclic polyolefins have attracted attention as polymers constituting films for optical applications. These polymers are materials with excellent heat resistance, transparency, and low hygroscopicity, and are polymers with a small photoelastic coefficient. Therefore, films using such polymers are less susceptible to retardation unevenness and It is a preferable material for weight reduction.

  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. As a film forming method different from the melting method, there is a solution 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 not easily affected by stress, so it is possible to obtain a film molded product with less in-plane variation in optical properties such as retardation. There is. The solution method 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.

  Conventionally, there is a method using a toluene solution when these resins are formed into a solution. However, since the boiling point of toluene is as high as 100 ° C. or higher, a high temperature is required for industrial production of a final product with few residual volatile components. Since it must be dried, it is colored or flatness is deteriorated (see Patent Document 1).

  When a solvent with 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. 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, it is preferable that the surface of the support is as smooth as possible so that the surface of the casting support is not transferred to the product film. Is naturally limited (see Patent Document 2).
Japanese Patent Laid-Open No. 9-12001 JP 2002-326240 A

  However, the method of dissolving a polycarbonate or alicyclic polyolefin as described above in a highly volatile solvent and forming a film by a solution method still has a problem in that a highly transparent film can be stably obtained. There is no industrially established method for obtaining a long film.

  Accordingly, an object of the present invention is to provide a biaxially stretched polyester film for optical resin solution film formation that is excellent in flatness and transparency and excellent in handling properties.

  The present invention employs the following means in order to solve such problems. That is, the biaxially stretched polyester film for forming an optical resin solution of the present invention has a weight ratio of polystyrene sulfonic acid and / or a salt thereof to a polyester resin on at least one side of the polyester film of 1/99 to 50/50. A biaxially stretched polyester film for forming an optical resin solution, wherein a resin layer in a range is formed.

  According to a preferred aspect of the biaxially stretched polyester film for forming an optical resin solution of the present invention, the polyester resin is copolymerized with 2 to 15 mol% of a monomer having a sulfonic acid group and / or its base. Polyester resin.

  According to a preferred embodiment of the biaxially stretched polyester film for forming an optical resin solution of the present invention, a crosslinking agent is added to the resin layer, and the addition amount with respect to the entire resin layer is 0.2 to 20% by weight. It is.

  According to a preferred embodiment of the biaxially stretched polyester film for forming an optical resin solution of the present invention, the surface roughness Ra of the resin layer surface of the polyester film is 3 to 20 nm, and the maximum protrusion height Rmax is 10 to 1000 nm. And the surface free energy of the resin layer surface of the said polyester film is 45-70 mN / m.

  According to a preferred aspect of the biaxially stretched polyester film for forming an optical resin solution of the present invention, the optical resin is a polycarbonate or an alicyclic polyolefin.

  ADVANTAGE OF THE INVENTION According to this invention, the biaxially stretched polyester film for optical resin solution film forming excellent in the planarity and transparency of the film using optical resin, and excellent in handling property can be obtained.

  Hereinafter, the biaxially stretched polyester film for forming an optical resin solution of the present invention will be described in more detail.

  The polyester constituting the 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- Mainly comprises at least one component selected from naphthalate, butylene terephthalate, propylene-2,6-naphthalate, ethylene-α, β-bis (2-chlorophenoxy) ethane-4,4′-dicarboxylate, and the like. It is a constituent component. These constituent components may be used singly or in combination of two or more. However, it is particularly preferable to use a polyester having ethylene terephthalate as the main constituent component, considering quality and economic efficiency. . These polyesters may be further partially copolymerized with other dicarboxylic acid components and other diol components, preferably 20 mol% or less.

  Further, in these polyesters, various additives such as antioxidants, heat stabilizers, weathering stabilizers, ultraviolet absorbers, infrared absorbers, organic lubricants, pigments, dyes, organic or inorganic fine particles, A filler, 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.

  Although the thickness of the polyester film used by this invention is suitably selected according to a use, from points, such as mechanical strength and handling property, Usually, it is the range of preferably 1-500 micrometers, More preferably, it is 10-300 micrometers. It is a range, Most preferably, it is the range of 50-200 micrometers.

  The biaxially stretched polyester film is generally stretched about 2.5 to 5 times in the longitudinal direction and the width direction of the unstretched polyester sheet or film, and then subjected to heat treatment to complete the crystal orientation. It is a thing which shows a biaxially oriented pattern by wide-angle X-ray diffraction.

  The polyester film for forming an optical resin solution is a polyester film used as a base film used when forming an optical resin in solution, and in the present invention, a specific biaxially stretched polyester film is used. It is preferable. Here, the biaxially stretched polyester film may be one in which a laminated film is formed on the surface of a biaxially stretched film made of polyester, or may not be formed. Thus, in the present invention, including a case where a laminated film is formed, it is generically called a biaxially stretched polyester film.

  In the present invention, polystyrene sulfonic acid and / or a salt thereof constituting the resin layer formed on such a polyester film includes polystyrene sulfonic acid, ammonium salt of polystyrene sulfonic acid, and alkali metal salts (Li, Na, K, etc.). Salt) and alkaline earth metal salts (salts of Mg, Ca, Ba, etc.), but are not limited thereto. Among them, particularly preferred are polystyrenesulfonic acid ammonium salt and alkali metal salt, although not particularly limited, the molecular weight is about 1,000 to 100,000, preferably about 5,000 to 20,000. Moreover, these can also use 2 or more types.

  In the present invention, the polystyrene sulfonic acid and salt constituting the resin layer may be copolymerized with other copolymerization components to the extent that the effects of the present invention are not impaired. Other copolymer components include alkyl acrylate, alkyl methacrylate (the alkyl group is methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, 2-ethylhexyl, Hydroxyl group-containing compounds such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate), lauryl group, stearyl group, cyclohexyl group, phenyl group, benzyl group and phenylethyl group) , Acrylamide, methacrylamide, N-methyl acrylamide, N-methyl methacrylamide, N-methylol acrylamide, N-methylol methacrylamide, N, N-dimethylol acrylamide, N-methyl Amide group-containing compounds such as xymethylacrylamide, N-methoxymethylmethacrylamide and N-phenylacrylamide, amino group-containing compounds such as N, N-diethylaminoethyl acrylate and N, N-diethylaminoethyl methacrylate, glycidyl acrylate and glycidyl methacrylate Epoxy group-containing compounds, acrylic acid, methacrylic acid and their salts (alkali metal salts, alkaline earth metal salts, ammonium salts, etc.) carboxyl groups or compounds containing such salts, allyl glycidyl ethers, etc. Compounds, vinyl sulfonic acid and its salts (such as lithium salt, sodium salt, potassium salt and ammonium salt), crotonic acid, itaconic acid, maleic acid, fumaric acid and their salts (lithium) A compound containing a carboxyl group such as a sodium salt, a sodium salt, a potassium salt and an ammonium salt) or a salt thereof, a compound containing an acid anhydride such as maleic anhydride, itaconic anhydride, vinyl isocyanate, allyl isocyanate, styrene, Use vinyl methyl ether, vinyl ethyl ether, vinyl trisalkoxysilane, alkyl maleic acid monoester, alkyl fumaric acid monoester, acrylonitrile, methacrylonitrile, alkyl itaconic acid monoester, vinylidene chloride, vinyl acetate, vinyl chloride, etc. These are copolymerized using one or two or more kinds, but are not limited thereto.

  In the present invention, the polyester resin constituting the resin layer formed on the polyester film is not particularly limited as long as it has an ester bond in the main chain or the side chain, but is polycondensed from an acid component and a glycol component. Can be obtained.

  Furthermore, the polyester resin is a polyester resin in which a monomer having a sulfonic acid group and its base is copolymerized in an amount of 2 to 15 mol%, preferably 3 to 13 mol%, more preferably 5 to 10 mol%. Is preferred. If the amount of the monomer is too small, sufficient adhesion durability may not be obtained. Moreover, when there is too much quantity of this monomer, it may become impossible to form a resin layer.

  As a polyester resin, you may use 2 or more types of polyester resins of a different copolymer composition in which the monomer amount which has a sulfonic acid group and its base exists in said range. The monomer in the present invention refers to an acid component and a glycol component that form a polyester resin.

  Moreover, it is preferable to use what melt | dissolves this polyester resin with hot water for the polyester resin which comprises the resin layer concerning this invention. Hot water is 50-100 degreeC water, and the preferable temperature range of hot water is 60-80 degreeC. Any resin that dissolves in hot water in the above temperature range is uniformly dispersed in an aqueous solution.

  Examples of the acid component constituting the polyester resin used in the present invention include terephthalic acid, isophthalic acid, phthalic acid, 2,5-dimethylterephthalic acid, 1,4-naphthalenedicarboxylic acid, biphenyldicarboxylic acid, and 2,6-naphthalenedicarboxylic acid. Acid, 1,2-bisphenoxyethane-p, p'-dicarboxylic acid, phenylindanedicarboxylic acid, 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, and acid components containing a sulfonic acid group and its base include, for example, sulfoterephthalic acid, 5-sulfo Isophthalic acid, 4-sulfoisophthalic acid, 4-sulfur Use of alkali metal salts such as naphthalene-2,7-dicarboxylic acid, sulfo-p-xylylene glycol, 2-sulfo-1,4-bis (hydroxyethoxy) benzene, alkaline earth metal salts, ammonium salts, etc. However, from the viewpoint of the planarity of the optical resin, the acid component containing a sulfonic acid group and its base is preferably a resin copolymerized in an amount of 3 to 25 mol%, more preferably 3 to 20 mol%. It is preferable that the resin is a cured resin.

  In this invention, in order to improve the adhesiveness with the polyester film of a polyester resin, it is also possible to copolymerize the compound containing carboxylate group.

  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 and other alkali metal salts, alkaline earth metal salts, ammonium salts, etc. Although it can be used, it is not limited to these.

  Examples of the glycol component constituting the polyester resin include ethylene glycol, diethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, and 1,5-pentane. Diol, 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-cyclohexanedimethanol, 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, o-, m-, and p-dihydroxybenzene, p, p′-isopropylidenediphenol, cyclopentane-1 , 2-diol, cyclohexane-1,2-diol, cyclohexane-1,4-diol, and the like, but are not limited thereto.

  In addition, as a polyester resin, a polyester resin or a modified polyester copolymer in which a monomer having a sulfonic acid group and its base is outside the above range within a range not impairing the effects of the present invention, for example, acrylic, It is also possible to use a mixture of a block copolymer or a graft copolymer modified with urethane and epoxy.

  In the present invention, when the resin layer is formed, the weight ratio of polystyrene sulfonic acid and / or salt thereof (A) to the polyester resin (B), that is, the solid content weight ratio (A / B) is 1/99 to 50. It is important to be / 50. The solid content weight ratio is preferably 4/96 to 40/60, more preferably 8/92 to 25/75. If the solid content weight ratio is too small, the planarity of the optical resin film deteriorates. If the solid content weight ratio is too large, not only a uniform coating film of the resin layer cannot be formed on the polyester film, but also the resin layer The slip resistance deteriorates. The inventors have not only improved the flatness of the optical resin film by balancing the adhesiveness and peelability with the optical resin by making the solid content weight ratio within a specific range, but also the resistance of the resin layer. It has been found that the slippage is improved, and it is possible to prevent contamination of the process when the optical resin is formed into a solution, and to reduce the defects of the optical resin film.

  In this invention, it is preferable that the crosslinking agent is added to the said resin layer, and the addition amount with respect to the whole resin layer is 0.2 to 20 weight%. The inventors have found that the addition of a crosslinking agent dramatically improves the shear resistance of the resin layer, prevents process contamination when the optical resin is formed into a solution, and the optical resin. It was possible to drastically reduce the defects of the film.

  The crosslinking agent used for the resin layer is not particularly limited as long as it can undergo a crosslinking reaction with a functional group present in the above-described resin, for example, a hydroxyl group, a carboxyl group, a methylol group, an amide group, etc. , Melamine crosslinking agent, oxazoline crosslinking agent, isocyanate crosslinking agent, aziridine crosslinking agent, epoxy crosslinking agent, methylolated or alkylolated urea, acrylamide, polyamide resin, various silane coupling agents, various A titanate coupling agent or the like can be used. In particular, a melamine-based crosslinking agent and an oxazoline-based crosslinking agent can be suitably used from the viewpoint of compatibility with the resin, adhesiveness, and the like.

  The melamine-based crosslinking agent preferably used in the present invention is not particularly limited, but is partially or completely etherified by reacting melamine, a methylolated melamine derivative obtained by condensing melamine and formaldehyde, or a methylolated melamine with a lower alcohol. Or a mixture thereof can be used. Moreover, as a melamine type crosslinking agent, a monomer, the condensate which consists of a multimer more than a dimer, or a mixture thereof can be used. As the lower alcohol used for etherification, methyl alcohol, ethyl alcohol, isopropyl alcohol, n-butanol, isobutanol and the like can be used. The functional group has an imino group, a methylol group, or an alkoxymethyl group such as a methoxymethyl group or a butoxymethyl group in one molecule, and an imino group type methylated melamine resin, a methylol group type melamine resin, or a methylol group type. Examples include methylated melamine resins and fully alkyl type methylated melamine resins. Among these, an imino group type melamine resin and a methylolated melamine resin are preferable, and an imino group type melamine resin is most preferable. Furthermore, an acidic catalyst such as p-toluenesulfonic acid may be used in order to promote thermal curing of the melamine-based crosslinking agent.

  The oxazoline-based crosslinking agent used in the present invention is not particularly limited as long as it has an oxazoline group as a functional group in the compound, but includes at least one monomer containing an oxazoline group, and What consists of an oxazoline group containing copolymer obtained by copolymerizing at least 1 type of another monomer is preferable.

  Monomers containing an oxazoline group 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 used, and one or a mixture of two or more thereof can also be used. Of these, 2-isopropenyl-2-oxazoline is preferred because it is easily available industrially.

  In the oxazoline-based cross-linking agent, the at least one other monomer used for the monomer containing the oxazoline group is not particularly limited as long as it is a monomer copolymerizable with the monomer containing the oxazoline group. Acrylates or methacrylates such as methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, acrylate-2-ethylhexyl, methacrylate-2-ethylhexyl, etc. Unsaturated carboxylic acids such as acid, methacrylic acid, itaconic acid and maleic acid, unsaturated nitriles such as acrylonitrile and methacrylonitrile, acrylamide, methacrylamide, N-methylolacrylamide, N-methylol methacrylate Contains unsaturated amides such as amides, vinyl esters such as vinyl acetate and vinyl propionate, vinyl ethers such as methyl vinyl ether and ethyl vinyl ether, olefins such as ethylene and propylene, vinyl chloride, vinylidene chloride and vinyl fluoride. Halogen- [alpha], [beta] -unsaturated monomers, [alpha], [beta] -unsaturated aromatic monomers such as styrene and [alpha] -methylstyrene can be used, and these should be used alone or in a mixture of two or more. You can also.

  In the laminated film of the present invention, the resin and the cross-linking agent can be mixed and used at an arbitrary ratio, but the cross-linking agent is added in an amount of 0.2 to 20% by weight based on the entire resin layer. It is preferable in terms of improvement, more preferably 0.5 to 15% by weight, and most preferably 1 to 10% by weight. When the addition amount of the crosslinking agent is less than 0.2% by weight, the effect of addition is small. When the addition amount exceeds 20% by weight, the adhesion tends to decrease.

  In the present invention, the resin layer may have other resin, for example, a polyester resin other than the above-described polyester resin, an acrylic resin, a urethane resin, an epoxy resin, or a polycarbonate resin, as long as the effects of the present invention are not impaired. Silicone resin, alkyd resin, urea resin, phenol resin, and the like may be blended.

  Furthermore, in the present invention, the resin layer has various additives such as an antioxidant, a heat stabilizer, a weather stabilizer, an ultraviolet absorber, a lubricant, and the like within the range where the effects of the present invention are not impaired. Pigments, dyes, organic or inorganic fine particles, fillers, antistatic agents, nucleating agents, and the like may be blended.

  In the present invention, it is optional to add particles to the resin layer, but the addition of these particles improves the slipperiness and handling properties of the polyester film.

  In the present invention, the particles arbitrarily added to the resin layer are not particularly limited, and aggregated silica, colloidal silica, alumina, alumina sol, kaolin, talc, mica, calcium carbonate, and the like can be used. Although the number average particle diameter is not specifically limited, 10 nm-2000 nm are preferable, More preferably, it is 40-1000 nm. Moreover, the mixing ratio with respect to all the resin in a resin layer is although it does not specifically limit, 0.05-8 weight part is preferable by solid content weight ratio, More preferably, it is 0.1-3 weight part.

  The method for forming the resin layer is not particularly limited, but a coating method, a coextrusion method, or the like is usually used. Various coating methods such as a reverse coating method, a gravure coating method, a rod coating method, a bar coating method, a die coating method, and a spray coating method can be used as a method for coating on a polyester film that is a base film. . Preferably, a method of applying a resin dissolved and dispersed in an organic solvent or water is used in the production process of the polyester film.

  In the present invention, the thickness of the resin layer is not particularly limited, but is preferably 0.02 to 5 μm, more preferably 0.03 to 2 μm, and most preferably 0.05 to 0.5 μm. is there. If the thickness of the resin layer is too thin, adhesion durability with the ink receiving layer, antistatic properties and water resistance may be poor.

  A polyester film for polarizing plate release is a polyester film used as a mold release and protective film when manufacturing and inspecting a polarizing plate, and is visually inspected by a crossed Nicol method in a state of being laminated with a polarizing plate and a retardation polarizing plate. A generic term for the polyester film to be implemented.

  In the present invention, the surface roughness Ra of the resin layer of the polyester film is preferably from 3 to 20 nm, more preferably from 5 to 15 nm, from the viewpoint of handling properties of the polyester film and transparency of the optical resin film. On the other hand, the maximum protrusion height Rmax of the resin layer of the polyester film is preferably 10 to 1000 nm, more preferably 20 to 800 nm. In order to set the surface roughness and the maximum protrusion height within the above ranges, a method of setting the number average particle diameter added to the resin layer in the above ranges is preferably used. The slip coefficient of the polyester film is preferably 0.6 or less, more preferably 0.5 or less.

  In the present invention, the surface roughness Ra and the maximum protrusion height are values obtained by measuring the center line average roughness Ra and the maximum protrusion height Rmax using a three-dimensional fine shape measuring instrument (ET-30HK) manufactured by Kosaka Laboratory. To do.

  The thickness unevenness in the width direction of the polyester film in the present invention is preferably 1.0 μm / 30 cm or less, more preferably 0.8 μm / 30 cm, from the viewpoint of visibility during inspection, thermal wrinkles, and the like.

  Moreover, the surface free energy of the resin layer surface of the polyester film used in the present invention is preferably 45 to 70 mN / N, more preferably 45 to 65 mN / N, and an optical resin film with good flatness is obtained. It is done. The surface free energy and its dispersive force component, polar force component, and hydrogen bond component can be determined by the so-called Kaelble method. Polym. Sci, A-2, 9, 363 (1971). In order to make the surface free energy within the above range, the weight ratio of polystyrene sulfonic acid and / or salt thereof to the polyester resin on the polyester film is 1/99 to 50/50, preferably 4/96 to 40/60, More preferably, a method of forming a resin layer of 8/92 to 25/75 is preferably used.

  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 (1) and / or chemical formula (2).

(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 (1) 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 a normal hydrogenation method to produce a polymer having a structural unit represented by the above chemical formula (1).

  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 (2) include one or more of the norbornene monomers and ethylene, and these 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 (2), 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 (1) or (2). 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, although the manufacturing method of the polyester film used by this invention is demonstrated, this invention is not limited to this.

  Polyethylene terephthalate, which is representative of polyester, is usually produced by one of the following processes. (1) A process in which terephthalic acid and ethylene glycol are used as raw materials, a low polymer is obtained by direct esterification reaction, and a high molecular weight polymer is obtained by subsequent polycondensation reaction, and (2) dimethyl terephthalate and ethylene glycol are used as raw materials In this process, a low polymer is obtained by a transesterification reaction, and a high molecular weight polymer is obtained by a subsequent polycondensation reaction. Here, the esterification reaction proceeds even without a catalyst, but in the present invention, a titanium compound may be added as a catalyst. Further, in the transesterification reaction, the reaction is allowed to proceed by using a conventionally known compound such as manganese, calcium, magnesium, zinc and lithium, or a titanium catalyst, and after the transesterification reaction is substantially completed, In order to inactivate the catalyst used, a phosphorus compound is added.

  The method for producing the polyester used in the present invention was obtained at any stage of the series of reactions (1) or (2) above, preferably in the first half of the series of reactions (1) or (2) above. After adding titanium oxide, a cobalt compound, or the like as particles to the low polymer, a titanium compound is added as a polycondensation catalyst and a polycondensation reaction is performed to obtain a high molecular weight polyester.

  In addition, the above reaction is carried out in a batch, semi-batch, or continuous system, but the present invention can be applied to any type of production method.

  Next, the polyester raw material obtained as described above is prepared in the form of pellets, etc., and if necessary, pre-drying is performed in hot air or under vacuum and supplied to the extruder. In the extruder, the resin that has been heated and melted to a temperature equal to or higher than the melting point passes through a heated pipe connecting a filter, a gear pump, and the like in a molten state to remove foreign matters. At this time, by connecting the gear pump, the uniformity of the extrusion amount of the resin is improved, and the effect of reducing the thickness unevenness is high.

  The resin sent to the die from the extruder is formed into a target shape by the die and then discharged. The resin temperature at the time of discharge is usually equal to or higher than the melting end temperature of the polyester used.

  The sheet-like molten resin discharged from the die is cooled and solidified on a casting drum and formed into a film. At this time, a method in which static electricity is applied to the sheet-like molten resin so that the sheet is brought into close contact with the drum and rapidly cooled and solidified is preferably used.

  The unstretched film thus obtained is led to a heated roll group, further heated to a temperature of 80 to 110 ° C. using an infrared heater, and 2 to 4 times in one or more stages in the longitudinal direction of the film. Stretching (longitudinal stretching) and cooling with a roll group having a temperature of 20 to 50 ° C.

  Subsequently, the film is guided to a transverse stretching machine while holding both ends of the film with clips, and is stretched 3 to 5 times in the transverse direction in a hot air atmosphere heated to a temperature of 100 to 150 ° C. The polyester film thus biaxially stretched is heat-set at a temperature of 180 to 240 ° C. in a tenter in order to impart flatness and dimensional stability, and is uniformly cooled and then cooled to room temperature and wound up. . It is possible to suppress the bowing of the polyester film by cooling to near room temperature once between the transverse stretching and heat setting, or by gradually raising the temperature so that the temperature difference is reduced from the transverse stretching to the heat setting. If necessary, the film can be relaxed in the longitudinal direction and the width direction after heat setting.

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

(1) Surface roughness (Ra) and maximum protrusion height (Rmax)
The center line average roughness Ra and the maximum protrusion height Rmax were measured using a three-dimensional fine shape measuring instrument (ET-30HK) manufactured by Kosaka Laboratory. The measurement conditions are as follows. The average value of 20 measurements was taken as the value.
・ Tip tip radius: 2μm
-Stylus load: 16mg
・ Measurement area: 0.3 mm ²
Cut-off: 0.25 mm.

(2) Surface free energy According to a known method, four types of liquids, water, ethylene glycol, formamide, and methylene iodide, were used as measurement liquids, and contact angle meter CA-D manufactured by Kyowa Interface Chemical Co., Ltd. The static contact angle with respect to the film surface of each liquid was calculated | required using the type | mold. Each component of the contact angle and the surface tension of the measurement liquid obtained for each liquid was substituted into the following equation, and simultaneous equations consisting of four equations were solved for γSd, γSp, and γSh.
(ΓSdγLd) 1/2 + (γSpγLp) 1/2 + (γShγLh)
1/2 = γL (1 + COS θ) / 2
However, γS = γSd + γSp + γSh
γL = γLd + γLp + γLh
γS, γSd, γSp, and γSh represent the surface free energy, dispersion force component, polar force component, and hydrogen bond component of the film surface, respectively, and γL, γLd, γLp, and γLh represent the respective measurement solutions used. It represents surface free energy, dispersion force component, polar force component, and hydrogen bond component. Here, as the surface tension of each liquid used, the value proposed by Panzer (J. Panzer, J. Colloid Interface Sci., 44, 142 (1973)) was used.

(3) Planarity After methylene chloride solution in which alicyclic polyolefin (JSR Co., Ltd. Arton G) as an optical resin is dissolved to a concentration of 20% by weight is applied on the obtained polyester film by a die coating method. After passing through an oven and drying at a temperature of 40 ° C. for 3 minutes, it was peeled from the polyester film to obtain an optical resin film. An optical resin film is spread on a cork base, and the surface is smoothed with a non-woven stick to eliminate air between the film and the base. The film state after being allowed to stand for 3 minutes was observed, and the height of the part where the film was lifted from the table was measured. Less than 1 mm was evaluated as ◯, less than 5 mm as Δ, and 5 mm or more as X. ○ is a pass.

(4) Haze The haze of the optical resin film obtained by the above method was measured according to JIS-K-7105 (1981).

(5) Slip resistance A biaxially stretched polyester film is slit into a tape having a width of 1/2 inch. Using a tape running tester, the resin layer is reciprocated on the guide pin so that the resin layer surface is in contact with the guide pin (material: SUS, surface roughness: 0.3S, diameter: 5 mm). A load of 500 g was applied to one end of the film, and after 10 reciprocations at a holding angle of 140 degrees and a running speed of 6.6 cm / min, the amount of white powder adhering to the film surface and the degree of film slippage were visually evaluated. did. The evaluation criteria are as follows. ◎ and ○ are acceptable.

Guide pin running part is not white powder: ◎
There is a slight amount of white powder at the end of the guide pin running part: ○
A large amount of white powder is attached to the entire guide pin travel part.

  Next, embodiments of the present invention will be described based on examples, but the present invention is not necessarily limited thereto.

Example 1
Polyethylene terephthalate substantially free of particles was dried under reduced pressure (3 Torr) at a temperature of 180 ° C. for 5 hours, then fed to an extruder and melted at a temperature of 280 ° C. After these polymers were filtered with high precision, T Extruded into a sheet from the letter-shaped base. The sheet-like material thus obtained was wound around a casting drum having a surface temperature of 20 ° C. by using an electrostatic application casting method, and solidified by cooling to produce an unstretched film. The unstretched film was stretched 3.3 times in the longitudinal direction at a temperature of 95 ° C., and then a resin layer-forming coating solution a having the following composition kept at a temperature of 25 ° C. was applied onto the uniaxially stretched film. While holding the uniaxially stretched film coated with the resin layer forming coating liquid a with a clip, it is heated to a temperature of 100 ° C., and the moisture content in the resin layer forming coating liquid a on the uniaxially stretched film is 50% by weight or less. Stretch 3.3 times in the width direction and heat-treat for 15 seconds at a temperature of 225 ° C. to obtain a biaxially stretched polyester film having a thickness of 125 μm and a resin layer thickness of 0.15 μm as a base PET film It was.

  Resin layer forming coating solution a: Polyester resin-1 consisting of polystyrene sulfonate ammonium (molecular weight 10,000) and acid component and glycol component shown in Table 1 below is mixed at a weight ratio of 15/85, and the average particle size is 100 nm. An aqueous coating solution containing 0.5% by weight of colloidal silica.

  The results are as shown in Table 7. The flatness, haze, and shear resistance were good.

(Example 2)
A biaxially stretched polyester film was prepared in the same manner as in Example 1 except that the composition of the resin layer forming coating solution a used in Example 1 was changed to the following resin layer forming coating solution b. The obtained biaxially stretched polyester film had good flatness, haze, and shear resistance. The results are shown in Table 7.

  Resin layer-forming coating solution b: Colloidal silica having an average particle size of 150 nm by mixing 5/95 by weight of polyester resin-2 comprising polystyrene sulfonate (molecular weight 20,000) and the acid component and glycol component shown in Table 2 below. Water-based coating liquid with 0.3% added.

(Example 3)
A biaxially stretched polyester film was prepared in the same manner as in Example 1 except that the composition of the resin layer forming coating solution a used in Example 1 was changed to the following resin layer forming coating solution c. This inkjet base film had good adhesion durability, antistatic properties and water resistance. The obtained biaxially stretched polyester film was slightly inferior in flatness but at a satisfactory level, and had good haze and shear resistance. The results are shown in Table 7.

  Resin layer-forming coating solution c: colloidal silica having an average particle size of 150 nm by mixing polystyrene sulfonate (molecular weight 10,000) and polyester resin-3 comprising the acid component and glycol component of Table 3 below in a weight ratio of 3/97 A water-based coating liquid containing 0.3% by weight.

Example 4
Polyethylene terephthalate containing 0.015% aggregated silica having an average particle size of 0.4 μm and 0.005% aggregated silica having an average particle size of 1.5 μm was dried under reduced pressure (3 Torr) at a temperature of 180 ° C. for 5 hours, The polymer was supplied to an extruder and melted at a temperature of 280 ° C., and these polymers were filtered with high precision, and then extruded into a sheet form from a T-shaped die. The sheet-like material thus obtained was wound around a casting drum having a surface temperature of 20 ° C. by using an electrostatic application casting method, and solidified by cooling to produce an unstretched film. The unstretched film was stretched 3.3 times in the longitudinal direction at a temperature of 95 ° C., and then a resin layer forming coating solution d having the following composition kept at a temperature of 25 ° C. was applied onto the uniaxially stretched film. While holding the uniaxially stretched film coated with the resin layer forming coating liquid d with a clip, it is heated to a temperature of 100 ° C., and the moisture content in the resin layer forming coating liquid d on the uniaxially stretched film is 50% by weight or less. Stretch 3.3 times in the width direction and heat-treat for 15 seconds at a temperature of 225 ° C. to obtain a biaxially stretched polyester film having a thickness of 125 μm and a resin layer thickness of 0.15 μm as a base PET film It was.

  Resin layer-forming coating solution d: A water-based coating solution obtained by mixing polystyrene resin ammonium having a molecular weight of 10,000 (molecular weight 10,000) and polyester resin-1 composed of an acid component and a glycol component in Table 4 below in a weight ratio of 15/85.

    The results are as shown in Table 7. The flatness, haze, and shear resistance were good.

(Example 5)
A biaxially stretched polyester film was prepared in the same manner as in Example 1 except that the composition of the resin layer forming coating solution a used in Example 1 was changed to the following resin layer forming coating solution b. The obtained biaxially stretched polyester film had good flatness, haze, and slip resistance. The results are shown in Table 7.

  Resin layer forming coating solution b: Colloidal polystyrene sulfonate (molecular weight 10,000) and polyester resin-1 consisting of an acid component and a glycol component shown in Table 1 below in a weight ratio of 10/90, and an average particle size of 150 nm An aqueous coating solution in which 0.3% by weight of silica and 2% by weight of methylolated melamine as a crosslinking agent are added to the resin layer.

(Example 6)
A biaxially stretched polyester film was prepared in the same manner as in Example 1 except that the composition of the resin layer forming coating solution a used in Example 1 was changed to the following resin layer forming coating solution b. The obtained biaxially stretched polyester film was slightly inferior in slip resistance but had no problem and had good flatness and haze. The results are shown in Table 7.

  Resin layer-forming coating solution b: Polystyrene sulfonate (molecular weight 20,000) and polyester resin-2 comprising the acid component and glycol component shown in Table 1 below are mixed at a weight ratio of 40/60, and a colloidal having an average particle size of 150 nm. An aqueous coating liquid containing 0.3% by weight of silica.

(Comparative Example 1)
A biaxially stretched polyester film was prepared in the same manner as in Example 1 except that the composition of the resin layer forming coating solution a used in Example 1 was changed to the following resin layer forming coating solution e. This biaxially stretched polyester film was inferior in flatness and haze. The results are shown in Table 7.

  Resin layer-forming coating solution e: A water-based coating solution composed of polyester resin-4 comprising the acid component and glycol component shown in Table 5 below.

(Comparative Example 2)
A biaxially stretched polyester film was prepared in the same manner as in Example 1 except that the composition of the resin layer forming coating solution a used in Example 1 was changed to the following resin layer forming coating solution f. The film was uneven and partly whitened, and had a very poor surface property. The results are shown in Table 7.

  Resin layer-forming coating solution f: Colloidal silica having an average particle diameter of 100 nm by mixing polystyrene sulfonate (molecular weight 10,000) and polyester resin-5 consisting of an acid component and a glycol component shown in Table 6 below in a weight ratio of 80/20 A water-based coating liquid containing 0.5%.

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

Claims (6)

An optical resin solution, wherein a resin layer having a weight ratio of polystyrene sulfonic acid and / or a salt thereof to a polyester resin in the range of 1/99 to 50/50 is formed on at least one surface of the polyester film. Biaxially stretched polyester film for film production. 2. The biaxial film for forming an optical resin solution according to claim 1, wherein the polyester resin is a polyester resin copolymerized with 2 to 15 mol% of a monomer having a sulfonic acid group and / or a base thereof. Stretched polyester film. 3. A biaxially stretched polyester for forming an optical resin solution according to claim 1, wherein a crosslinking agent is added to the resin layer, and the amount added is 0.2 to 20% by weight based on the entire resin layer. the film. 4. The optical resin solution according to claim 1, wherein the surface roughness Ra of the resin layer surface of the polyester film is 3 to 20 nm, and the maximum protrusion height Rmax is 10 to 1000 nm. Biaxially stretched polyester film for film production. The biaxially stretched polyester film for forming an optical resin solution according to any one of claims 1 to 4, wherein the surface free energy of the resin layer surface of the polyester film is 45 to 70 mN / m. 6. The biaxially stretched polyester film for forming an optical resin solution according to claim 1, wherein the optical resin is polycarbonate or alicyclic polyolefin.