JP2011215171A - Optical film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the following problems: a resin film including an acrylic polymer has excellent surface smoothness, so that when the resin films come in contact with each other or the film comes in contact with another base material, they are closely adhere to each other and peeling them is difficult.SOLUTION: In an optical film having the resin film including a (meth)acrylic polymer and a urethane resin layer including a urethane resin and fine particles (A), an average particle diameter of the fine particles (A) is set to be 250 nm or greater and the resin film includes fine particles (B). Thereby blocking occurring during winding up is effectively suppressed and the optical film having excellent conveying properties and winding properties is attained.

Description

  The present invention relates to an optical film having a resin film containing a (meth) acrylic polymer.

  Acrylic resin has high optical properties such as low light elastic modulus while having high light transmittance, excellent surface gloss and weather resistance, and balance of mechanical strength, moldability and surface hardness. Therefore, it is widely used for optical applications in automobiles and home appliances.

  In a liquid crystal display device which is a typical image display device, it is indispensable to dispose polarizing plates on both sides of the liquid crystal cell due to the image forming method. The polarizing plate is usually formed by adhering a polarizer protective film on both surfaces of a polarizer using an adhesive. An acrylic resin film has been proposed as a material for forming a polarizer protective film. Moreover, in order to improve the adhesiveness of a polarizer and an acrylic resin film, providing an easily bonding layer between a polarizer and an acrylic resin film is proposed (for example, patent document 1, 2).

JP 2007-127893 A JP 2010-55062 A

  However, since the acrylic resin film is excellent in surface smoothness, it has a property that it is difficult to be peeled off when it comes into contact with films or other base materials. As a method for solving these problems, a method of imparting anti-blocking properties by making irregularities on the surface using fine particles such as silica particles is known.

  The silica particles are known to be 1) coating on the surface layer, 2) a method of adding by kneading to the resin, but in the case of 1), the opposite surface of the film has no anti-blocking property, so that the post-process In the case of 2), there are many fine particles not involved in the anti-blocking property in the case of 2), which makes it difficult to achieve both internal haze and anti-blocking properties. There was a problem of becoming.

  The present invention has been made in order to solve the above-described conventional problems, and a main object thereof is to provide an optical film that is excellent in film transportability and can suppress blocking that occurs during winding.

  The optical film of the present invention is an optical film having a resin film containing a (meth) acrylic polymer and a urethane resin layer containing a urethane resin and fine particles (A), and the average particle of the fine particles (A) The diameter is 250 nm or more, and the resin film contains fine particles (B).

  In the optical film of the present invention, the (meth) acrylic polymer preferably has a ring structure in the main chain.

  In the optical film of the present invention, the resin film preferably contains a styrene polymer.

  In the optical film of the present invention, the content of the fine particles (A) in the urethane resin layer is preferably 0.05% by mass or more and 2.0% by mass or less.

  In the optical film of the present invention, the average particle size of the fine particles (A) is preferably larger than the average particle size of the fine particles (B).

  In the optical film of the present invention, the average particle size of the fine particles (B) is preferably 10 nm or more and 500 nm or less.

  In the optical film of the present invention, the content of fine particles (B) in the resin film is preferably 0.01% by mass or more and 1.0% by mass or less.

  According to the present invention, in an optical film having a urethane resin layer containing a urethane resin and fine particles (A) on a resin film containing a (meth) acrylic polymer, the average particle size of the fine particles (A) is 250 nm or more. In addition, when the resin film contains the fine particles (B), blocking that occurs during winding can be effectively suppressed, and an optical film excellent in winding property can be provided. Specifically, by setting the average particle diameter of the fine particles (A) of the urethane resin layer to 250 nm or more, irregularities are formed on the surface of the urethane resin layer, and the resin film contains the fine particles (B). The frictional force at the contact surface between the film and the urethane resin layer and / or the urethane resin layer can be reduced. As a result, in the process of winding the optical film into a roll, it is possible to effectively prevent the occurrence of defects such as wrinkles and wrinkle marks without using interleaving paper, and excellent transportability and winding properties. An optical film can be provided.

  Hereinafter, although preferable embodiment of this invention is described, this invention is not limited to these embodiment. In the following description, unless otherwise specified, “%” means “% by mass”, “parts” means “parts by mass”, and “A to B” representing a range means “A or more and B or less”. To do.

[Resin film]
The resin film in the optical film of the present invention is not particularly limited as long as it contains a (meth) acrylic polymer and further contains fine particles (B).

  The (meth) acrylic polymer is a polymer having a (meth) acrylic acid ester unit and / or a (meth) acrylic acid unit as a constituent unit, and is a (meth) acrylic acid ester or (meth) acrylic acid. You may have the structural unit derived from a derivative | guide_body. The total of the proportions of the structural units derived from the (meth) acrylic acid ester unit, the (meth) acrylic acid unit and the above derivatives in all structural units of the (meth) acrylic polymer is usually 50% or more, preferably Is 60% or more, more preferably 70% or more.

  (Meth) acrylic acid ester units are, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, t- (meth) acrylic acid t- Butyl, n-hexyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, benzyl (meth) acrylate, dicyclopentanyloxyethyl (meth) acrylate, (meth) acryl Dicyclopentanyl acid, chloromethyl (meth) acrylate, 2-chloroethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, (meth) acrylic acid 2, 3,4,5,6-pentahydroxyhexyl, 2,3,4,5-tetrahydro (meth) acrylic acid Shipenchiru is a structural unit derived from 2- (hydroxymethyl) acrylate, 2- (hydroxymethyl) acrylate, a monomer such as 2- (hydroxyethyl) acrylate.

  The (meth) acrylic acid unit is a structural unit derived from a monomer such as acrylic acid, methacrylic acid, crotonic acid, 2- (hydroxymethyl) acrylic acid, 2- (hydroxyethyl) acrylic acid, and the like.

  The (meth) acrylic polymer may have two or more of these structural units as a (meth) acrylic acid ester unit and a (meth) acrylic acid unit. The (meth) acrylic polymer preferably has a methyl methacrylate unit. In this case, the thermal stability of the resin film containing the (meth) acrylic polymer is improved.

  The (meth) acrylic polymer preferably has a ring structure in the main chain. By including a ring structure in the main chain, the glass transition temperature (Tg) of the (meth) acrylic polymer is increased, and the heat resistance of the resin film is improved. Thus, a resin film containing a (meth) acrylic polymer having a ring structure in the main chain is suitable for use as an optical member because it can be easily placed near a heat generating part such as a light source in an image display device.

  The glass transition temperature (Tg) of the (meth) acrylic polymer is preferably 115 ° C. or higher, more preferably 120 ° C. or higher, and further preferably 130 ° C. or higher because the heat resistance of the optical film of the present invention is improved. The upper limit of Tg of the (meth) acrylic polymer is not particularly limited, but is preferably 180 ° C. or less from the viewpoint of moldability and the like.

  Although the kind of ring structure is not specifically limited, For example, it is at least 1 sort (s) chosen from lactone ring structure, glutaric anhydride structure, glutarimide structure, N-substituted maleimide structure, and maleic anhydride structure.

  The following general formula (1) shows a glutaric anhydride structure and a glutarimide structure.

上記一般式（１）におけるＲ^１、Ｒ^２は互いに独立して水素原子、またはメチル基であり、Ｘ^１は酸素原子または窒素原子である。Ｘ^１が酸素原子であるとき、Ｒ^３は存在せず、Ｘ^１が窒素原子のとき、Ｒ^３は、水素原子、炭素数１から６の直鎖アルキル基、シクロペンチル基、シクロヘキシル基、ベンジル基またはフェニル基である。

In the general formula (1), R ¹ and R ² are each independently a hydrogen atom or a methyl group, and X ¹ is an oxygen atom or a nitrogen atom. When X ¹ is an oxygen atom, R ³ is not present, and when X ¹ is a nitrogen atom, R ³ is a hydrogen atom, a linear alkyl group having 1 to 6 carbon atoms, a cyclopentyl group, a cyclohexyl group, a benzyl group Or it is a phenyl group.

When X ¹ is an oxygen atom, the ring structure represented by the general formula (1) is a glutaric anhydride structure. The glutaric anhydride structure can be formed, for example, by subjecting a copolymer of (meth) acrylic acid ester and (meth) acrylic acid to dealcoholization cyclocondensation in the molecule.

When X ¹ is a nitrogen atom, the ring structure represented by the general formula (1) is a glutarimide structure. The glutarimide structure can be formed, for example, by imidizing a (meth) acrylic acid ester polymer with an imidizing agent such as methylamine.

  The following general formula (2) shows a maleic anhydride structure and an N-substituted maleimide structure.

上記一般式（２）におけるＲ^４、Ｒ^５は互いに独立して水素原子、またはメチル基であり、Ｘ^２は酸素原子または窒素原子である。Ｘ^２が酸素原子であるとき、Ｒ^６は存在せず、Ｘ^２が窒素原子のとき、Ｒ^６は、水素原子、炭素数１から６の直鎖アルキル基、シクロペンチル基、シクロヘキシル基、ベンジル基またはフェニル基である。

In the general formula (2), R ⁴ and R ⁵ are each independently a hydrogen atom or a methyl group, and X ² is an oxygen atom or a nitrogen atom. When X ² is an oxygen atom, R ⁶ is not present, and when X ² is a nitrogen atom, R ⁶ is a hydrogen atom, a linear alkyl group having 1 to 6 carbon atoms, a cyclopentyl group, a cyclohexyl group, a benzyl group. Or it is a phenyl group.

When X ² is an oxygen atom, the ring structure represented by the general formula (2) is a maleic anhydride structure. The maleic anhydride structure can be formed, for example, by copolymerizing maleic anhydride and (meth) acrylic acid ester.

When X ² is a nitrogen atom, the ring structure represented by the general formula (2) is an N-substituted maleimide structure. The N-substituted maleimide structure can be formed, for example, by polymerizing an N-substituted maleimide such as phenylmaleimide and a (meth) acrylic acid ester.

  In each method for forming the ring structure exemplified in the description of the general formulas (1) and (2), all polymers used for forming each ring structure have a (meth) acrylate unit as a single unit. The resin obtained by this method is an acrylic resin.

  The lactone ring structure that the (meth) acrylic polymer may have in the main chain is not particularly limited. For example, it may be a 4- to 8-membered ring, but it is excellent in stability of the ring structure. A membered ring or a 6-membered ring is preferable, and a 6-membered ring is more preferable. The lactone ring structure which is a 6-membered ring is, for example, the structure disclosed in Japanese Patent Application Laid-Open No. 2004-168882, but the lactone ring structure is high due to the high polymerization yield of the precursor and the cyclization condensation reaction of the precursor. A structure represented by the following general formula (3) is obtained because a (meth) acrylic polymer having a ring content can be obtained and a polymer having a methyl methacrylate unit as a constituent unit can be used as a precursor. preferable.

上記一般式（３）において、Ｒ^７、Ｒ^８およびＲ^９は、互いに独立して、水素原子または炭素数１から２０の範囲の有機残基である。当該有機残基は酸素原子を含んでいてもよい。

In the general formula (3), R ⁷ , R ⁸ and R ⁹ are each independently a hydrogen atom or an organic residue having 1 to 20 carbon atoms. The organic residue may contain an oxygen atom.

  The organic residue in the general formula (3) is, for example, an alkyl group having 1 to 20 carbon atoms such as a methyl group, an ethyl group, a propyl group, or a butyl group, an alkyl group having 1 to 20 carbon atoms such as an ethenyl group, or a propenyl group. An aromatic hydrocarbon group having 1 to 20 carbon atoms, such as an unsaturated aliphatic hydrocarbon group, a phenyl group, or a naphthyl group, in the range, the alkyl group, the unsaturated aliphatic hydrocarbon group, and the aromatic carbon group. In the hydrogen group, one or more hydrogen atoms may be substituted with at least one group selected from a hydroxyl group, a carboxyl group, an ether group, and an ester group.

  Although the content rate of the said ring structure except the lactone ring structure in a (meth) acrylic-type polymer is not specifically limited, For example, it is 5-90 mass%, Preferably it is 10-70 mass%, More preferably, it is 10-70 mass%. It is 60 mass%, More preferably, it is 10-50 mass%.

  When the (meth) acrylic polymer has a lactone ring structure in the main chain, the content of the lactone ring structure in the resin is not particularly limited, but is, for example, 5 to 90% by mass, preferably 10 to 80% by mass. More preferably, it is 10-70 mass%, More preferably, it is 20-60 mass%.

  If the content of the ring structure in the (meth) acrylic polymer becomes transiently small, the heat resistance of the film may be lowered, and the solvent resistance and surface hardness may be insufficient. On the other hand, when the above content rate increases transiently, the moldability and mechanical properties of the film deteriorate.

  The (meth) acrylic polymer having a ring structure in the main chain can be produced by a known method. An acrylic resin whose ring structure is a glutaric anhydride structure or a glutarimide structure can be produced, for example, by the method described in WO2007 / 26659 or WO2005 / 108438. An acrylic resin whose ring structure is a maleic anhydride structure or an N-substituted maleimide structure can be produced, for example, by the method described in JP-A-57-153008 and JP-A-2007-31537. An acrylic resin whose ring structure is a lactone ring structure can be produced by, for example, the method described in JP-A-2006-96960, JP-A-2006-171464, or JP-A-2007-63541.

  The (meth) acrylic polymer may have a structural unit other than the (meth) acrylic acid ester unit and the (meth) acrylic acid unit, and such a structural unit includes, for example, styrene, vinyltoluene, α -Methylstyrene, α-hydroxymethylstyrene, α-hydroxyethylstyrene, acrylonitrile, methacrylonitrile, methallyl alcohol, allyl alcohol, ethylene, propylene, 4-methyl-1-pentene, vinyl acetate, 2-hydroxymethyl-1 -A structural unit derived from monomers such as butene, methyl vinyl ketone, N-vinyl pyrrolidone, N-vinyl carbazole. The (meth) acrylic polymer may have two or more of these structural units.

  The weight average molecular weight of the (meth) acrylic polymer is, for example, in the range of 1,000 to 500,000, preferably in the range of 5,000 to 350,000, more preferably in the range of 10,000 to 250,000, and still more preferably in the range of 50,000 to 200,000. It is a range.

  The resin film may have ultraviolet absorbing ability as long as it does not impair heat resistance, physical properties, and optical characteristics. Specifically, a method using an ultraviolet-absorbing monomer and / or an ultraviolet-stable monomer as a monomer component when producing a (meth) acrylic polymer, an ultraviolet absorber and / or an ultraviolet-stable There exists a method of mix | blending an agent with the said (meth) acrylic-type polymer. In addition, these methods may be used in combination as long as the resin film containing the (meth) acrylic polymer is not hindered. In order to maintain the ultraviolet absorbing function, it is preferable to use an ultraviolet absorbing monomer and an ultraviolet stabilizing monomer in combination, or to use an ultraviolet absorber and an ultraviolet stabilizer in combination. It is also preferable to use an ultraviolet absorber and / or an ultraviolet stabilizer in combination with the ultraviolet absorbing monomer and / or the ultraviolet stabilizing monomer.

  Examples of the ultraviolet absorbing monomer include benzotriazole compounds, benzophenone compounds or triazine compounds and acrylic monomers having a polymerizable unsaturated group. Examples of benzotriazole compounds include 2- [2′-hydroxy-5 ′-(meth) acryloyloxymethylphenyl] -2H-benzotriazole, 2- [2′-hydroxy-5 ′-(meth) acryloyloxyethyl. Phenyl] -2H-benzotriazole, 2- [2′-hydroxy-5 ′-(meth) acryloyloxypropylphenyl] -2H-benzotriazole, 2- [2′-hydroxy-5 ′-(meth) acryloyloxyhexyl Phenyl] -2H-benzotriazole, 2- [2′-hydroxy-3′-tert-butyl-5 ′-(meth) acryloyloxyethylphenyl] -2H-benzotriazole, 2- [2′-hydroxy-5 ′ -(Β- (Meth) acryloyloxyethoxy) -3′-tert-butyl Enyl] -5-tert-butyl-2H-benzotriazole, 2- [2′-hydroxy-3′-methacrylaminomethyl-5 ′-(1 ″, 1 ″, 3 ″, 3 ″ -tetramethyl) butylphenyl ] -2H-benzotriazole and the like can be used. Examples of the benzophenone compounds include 2-hydroxy-4- [2- (meth) acryloyloxy] ethoxybenzophenone, 2-hydroxy-4- [2- (meth) acryloyloxy] butoxybenzophenone, 2,2 ′. -Dihydroxy-4- [2- (meth) acryloyloxy] ethoxybenzophenone, 2-hydroxy-4- [2- (meth) acryloyloxy] ethoxy-4 '-(2-hydroxyethoxy) benzophenone, and the like can be used. . Examples of the triazine compound include 4-diphenyl-6- [2-hydroxy-4- (2-acryloyloxyethoxy)]-s-triazine, 2,4-bis (2-methylphenyl) -6- [2-Hydroxy-4- (2-acryloyloxyethoxy)]-s-triazine, 2,4-bis (2-methoxyphenyl) -6- [2-hydroxy-4- (2-acryloyloxyethoxy)]- An s-triazine or the like can be used. When using such an ultraviolet-absorbing monomer, it is preferably copolymerized in an amount of 0.1 to 25% by weight, more preferably 1 to 15% by weight of all monomers. . If the content is small, the contribution to improving the weather resistance is low, and if the content is too large, the hot water resistance and solvent resistance may decrease or yellowing may occur.

  As the UV-stable monomer, a monomer having a polymerizable unsaturated group bonded to a hindered amine compound can be used, and specific examples include 4- (meth) acryloyloxy-2,2,6,6. -Tetramethylpiperidine, 4- (meth) acryloylamino-2,2,6,6-tetramethylpiperidine, 4- (meth) acryloyloxy-1,2,2,6,6-pentamethylpiperidine, 4- ( (Meth) acryloylamino-1,2,2,6,6-pentamethylpiperidine, 4-cyano-4- (meth) acryloylamino-2,2,6,6-tetramethylpiperidine, 4-crotonoyloxy-2 , 2,6,6-tetramethylpiperidine, 4-crotonoylamino-2,2,6,6-tetramethylpiperidine, 1- (meth) acryloyl-4- (me ) Acryloylamino-2,2,6,6-tetramethylpiperidine, 1- (meth) acryloyl-4-cyano-4- (meth) acryloylamino-2,2,6,6-tetramethylpiperidine, 1-crotonoyl -4-crotonoyloxy-2,2,6,6-tetramethylpiperidine and the like. When such an ultraviolet-stable monomer is used, it is preferably copolymerized in an amount of 0.1 to 25% by weight, more preferably 1 to 15% by weight of all monomers. . If the content is small, the contribution to improving the weather resistance is low, and if the content is too large, the hot water resistance and solvent resistance may decrease or yellowing may occur.

  Examples of the ultraviolet absorber include benzophenone compounds, salicinate compounds, benzoate compounds, triazole compounds, and triazine compounds. Examples of the benzophenone compounds include 2,4-dihydroxybenzophenone, 4-n-octyloxy-2-hydroxybenzophenone, 2,2′-dihydroxy-4,4′-dimethoxybenzophenone, 2-hydroxy-4-n-octyl. Examples thereof include oxybenzophenone, bis (5-benzoyl-4-hydroxy-2-methoxyphenyl) methane, 1,4-bis (4-benzoyl-3-hydroxyphenone) -butane and the like. Examples of the silicate compound include pt-butylphenyl silicate. Examples of the benzoate compound include 2,4-di-t-butylphenyl-3 ', 5'-di-t-butyl-4'-hydroxybenzoate. Examples of triazole compounds include 2,2′-methylenebis [4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol], 2- (3 , 5-Di-tert-butyl-2-hydroxyphenyl) -5-chlorobenzotriazole, 2- (2H-benzotriazol-2-yl) -p-cresol, 2- (2H-benzotriazol-2-yl) -4,6-bis (1-methyl-1-phenylethyl) phenol, 2-benzotriazol-2-yl-4,6-di-tert-butylphenol, 2- [5-chloro (2H) -benzotriazole- 2-yl] -4-methyl-6-tert-butylphenol, 2- (2H-benzotriazol-2-yl) -4,6-di-tert-butylphenol, 2- 2H-benzotriazol-2-yl) -4- (1,1,3,3-tetramethylbutyl) phenol, 2- (2H-benzotriazol-2-yl) -4-methyl-6- (3,4) , 5,6-tetrahydrophthalimidylmethyl) phenol, methyl 3- (3- (2H-benzotriazol-2-yl) -5-tert-butyl-4-hydroxyphenyl) propionate / polyethylene glycol 300 reaction product 2- (2H-benzotriazol-2-yl) -6- (linear and side chain dodecyl) -4-methylphenol, 2- (5-methyl-2-hydroxyphenyl) benzotriazole, 2- [2- Hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole, 3- (2H-benzotriazol-2-yl ) -5- (1,1-dimethylethyl) -4-hydroxy -C7-9 side chain and straight chain alkyl esters. Further, triazine compounds include 2,4-diphenyl-6- (2-hydroxy-4-methoxyphenyl) -1,3,5-triazine, 2,4-diphenyl-6- (2-hydroxy-4-). Ethoxyphenyl) -1,3,5-triazine, 2,4-diphenyl- (2-hydroxy-4-propoxyphenyl) -1,3,5-triazine, 2,4-diphenyl- (2-hydroxy-4-) Butoxyphenyl) -1,3,5-triazine, 2,4-diphenyl-6- (2-hydroxy-4-butoxyphenyl) -1,3,5-triazine, 2,4-diphenyl-6- (2- Hydroxy-4-hexyloxyphenyl) -1,3,5-triazine, 2,4-diphenyl-6- (2-hydroxy-4-octyloxyphenyl) -1,3,5-tria 2,4-diphenyl-6- (2-hydroxy-4-dodecyloxyphenyl) -1,3,5-triazine, 2,4-diphenyl-6- (2-hydroxy-4-benzyloxyphenyl)- 1,3,5-triazine, 2,4-diphenyl-6- (2-hydroxy-4-butoxyethoxy) -1,3,5-triazine, 2,4-bis (2-hydroxy-4-butoxyphenyl) And -6- (2,4-dibutoxyphenyl) -1,3-5-triazine. Among them, 2,4-bis (2,4-dimethylphenyl) -6- [2-hydroxy-4- (3-) is highly compatible with (meth) acrylic polymers and has excellent absorption characteristics. And an ultraviolet absorber having an alkyloxy-2-hydroxypropyloxy) -5-α-cumylphenyl] -s-triazine skeleton (alkyloxy; a long-chain alkyloxy group such as octyloxy, nonyloxy, decyloxy, etc.). Examples of commercially available products include “Tinuvin 1577”, “Tinuvin 460” and “Tinuvin 477” (manufactured by Ciba Japan) as triazine-based UV absorbers, and “Adeka Stub LA-31” (manufactured by ADEKA) as triazole-based UV absorbers. It is done.

  These can be used alone or in combination of two or more. Although the compounding quantity of the said ultraviolet absorber is not specifically limited, It is preferable that it is 0.01-25 mass% in the film containing a (meth) acrylic-type polymer, More preferably, it is 0.05-10 mass%. . If the amount added is too small, the contribution to improving weather resistance is low, and if it is too large, the mechanical strength may be lowered or yellowing may be caused.

  The resin film may contain other thermoplastic resins in addition to the (meth) acrylic polymer. Examples of other thermoplastic resins include olefin polymers such as polyethylene, polypropylene, ethylene-propylene copolymer, poly (4-methyl-1-pentene); vinyl chloride, vinylidene chloride, chlorinated vinyl resins, and the like. Vinyl halide polymers; acrylic polymers such as polymethyl methacrylate; styrene polymers such as polystyrene, styrene-methyl methacrylate copolymer, styrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene block copolymer Polyesters such as polyethylene terephthalate, polybutylene terephthalate and polyethylene naphthalate; polyamides such as nylon 6, nylon 66 and nylon 610; polyacetals; polycarbonates; polyphenylene oxides; Polyetheretherketone; Polysulfone; Polyethersulfone; Polyoxybenzylene; Polyamideimide; Rubber polymer such as ABS resin and ASA resin blended with polybutadiene rubber and acrylic rubber, and especially styrene-acrylonitrile Styrenic polymers such as ABS resin and ASA resin blended with a copolymer or acrylic rubber are preferred.

  The content ratio of the other thermoplastic resin in the resin film is preferably 0 to 50% by mass, more preferably 0 to 40% by mass, and still more preferably 0 to 35% by mass.

  The resin film may contain an additive. Examples of additives include hindered phenol-based, phosphorus-based and sulfur-based antioxidants; weather-resistant stabilizers, stabilizers such as heat stabilizers; reinforcing materials such as glass fibers and carbon fibers; phenyl salicylates; UV absorbers such as (2,2′-hydroxy-5-methylphenyl) benzotriazole and 2-hydroxybenzophenone; near infrared absorbers; flame retardants such as tris (dibromopropyl) phosphate, triallyl phosphate and antimony oxide; anions -Based, cationic and nonionic surfactants; colorants such as inorganic pigments, organic pigments and dyes; organic fillers and inorganic fillers; resin modifiers; organic fillers and inorganic fillers; plasticizers A lubricant, an antistatic agent, a flame retardant, a phase difference adjusting agent, and the like.

  A known antioxidant can be used as the antioxidant. Examples of phenolic antioxidants include n-octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, n-octadecyl-3- (3,5-di-t-butyl). -4-hydroxyphenyl) acetate, n-octadecyl-3,5-di-t-butyl-4-hydroxybenzoate, n-hexyl-3,5-di-t-butyl-4-hydroxyphenylbenzoate, n-dodecyl 3,5-di-t-butyl-4-hydroxyphenylbenzoate, neododecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, dodecyl-β- (3,5-di- t-butyl-4-hydroxyphenyl) propionate, ethyl-α- (4-hydroxy-3,5-di-t-butylphenyl) isobutyrate Octadecyl-α- (4-hydroxy-3,5-di-t-butylphenyl) isobutyrate, octadecyl-α- (4-hydroxy-3,5-di-t-butyl-4-hydroxyphenyl) propionate, 2- (n-octylthio) ethyl-3,5-di-t-butyl-4-hydroxybenzoate, 2- (n-octylthio) ethyl-3,5-di-t-butyl-4-hydroxyphenyl acetate, 2 -(N-octadecylthio) ethyl-3,5-di-t-butyl-4-hydroxyphenyl acetate, 2- (n-octadecylthio) ethyl-3,5-di-t-butyl-4-hydroxybenzoate, 2- (2-hydroxyethylthio) ethyl-3,5-di-t-butyl-4-hydroxybenzoate, diethyl glycol bis- (3,5 -Di-t-butyl-4-hydroxy-phenyl) propionate, 2- (n-octadecylthio) ethyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, stearamide-N, N -Bis- [ethylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], n-butylimino-N, N-bis- [ethylene-3- (3,5-di-t -Butyl-4-hydroxyphenyl) propionate], 2- (2-stearoyloxyethylthio) ethyl-3,5-di-t-butyl-4-hydroxybenzoate, 2- (2-stearoyloxyethylthio) ethyl- 7- (3-Methyl-5-tert-butyl-4-hydroxyphenyl) heptanoate, 1,2-propylene glycol bis- [3- (3,5 Di-t-butyl-4-hydroxyphenyl) propionate], ethylene glycol bis- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], neopentyl glycol bis- [3- (3 , 5-di-t-butyl-4-hydroxyphenyl) propionate], ethylene glycol bis- (3,5-di-t-butyl-4-hydroxyphenyl acetate), glycerin-1-n-octadecanoate- 2,3-bis- (3,5-di-t-butyl-4-hydroxyphenyl acetate), pentaerythritol tetrakis- [3- (3 ', 5'-di-t-butyl-4'-hydroxyphenyl) Propionate], 1,1,1-trimethylolethanetris- [3- (3,5-di-tert-butyl-4-hydroxypheny ) Propionate], sorbitol hexa- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 2-hydroxyethyl-7- (3-methyl-5-tert-butyl-4-hydroxy Phenyl) propionate, 2-stearoyloxyethyl-7- (3-methyl-5-tert-butyl-4-hydroxyphenyl) heptanoate, 1,6-n-hexanediol bis-[(3 ', 5'-di- t-butyl-4-hydroxyphenyl) propionate], pentaerythritol tetrakis- (3,5-di-t-butyl-4-hydroxyhydrocinnamate), 3,9-bis [1,1-dimethyl-2- [ [beta]-(3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy] ethyl] 2,4,8,10-tetrao Saspiro [5,5] -undecane, 2,4-di-t-amyl-6- [1- (3,5-di-t-amyl-2-hydroxyphenyl) ethyl] phenyl acrylate and 2-t-butyl -6- (3-t-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate.

  Examples of the thioether-based antioxidant include pentaerythrityl tetrakis (3-laurylthiopropionate), dilauryl-3,3′-thiodipropionate, dimyristyl-3,3′-thiodipropionate, distearyl. -3,3'-thiodipropionate.

  Examples of phosphorus antioxidants include tris (2,4-di-t-butylphenyl) phosphite, 2-[[2,4,8,10-tetrakis (1,1-dimethylethyl) dibenzo [d. , F] [1,3,2] dioxaphosphin-6-yl] oxy] -N, N-bis [2-[[2,4,8,10-tetrakis (1,1 dimethylethyl) dibenzo [D, f] [1,3,2] dioxaphosphin-6-yl] oxy] -ethyl] ethanamine, diphenyltridecyl phosphite, triphenyl phosphite, 2,2-methylenebis (4,6- Di-t-butylphenyl) octyl phosphite, bis (2,6-di-t-butyl-4-methylphenyl) pentaerythritol diphosphite, distearyl pentaerythritol diphosphite DOO, cyclic neopentanetetraylbis (2,6-di -t- butyl-4-methylphenyl) phosphite and the like.

  The content of the additive in the resin film is preferably 0 to 5% by mass, more preferably 0 to 2% by mass, and still more preferably 0 to 0.5% by mass.

  The content of the (meth) acrylic polymer in the resin film is preferably 50 to 100% by mass, more preferably 50 to 99% by mass, further preferably 60 to 98% by mass, and particularly preferably 65 to 97% by mass. is there. When the content of the (meth) acrylic polymer in the resin film is less than 50% by mass, the high heat resistance and high transparency inherent in the (meth) acrylic polymer may not be sufficiently reflected. .

  The fine particles (B) contained in the resin film have an effect of imparting anti-blocking properties to the film by being contained in the resin film.

  The content of the fine particles (B) in the resin film is preferably 0.01% by mass or more and 1.0% by mass or less, more preferably 0.02% by mass or more and 0.5% by mass or less, and 0.05% by mass. % To 0.2% by mass is more preferable. When the content of the fine particles (B) is less than 0.01% by mass, the anti-blocking property is not sufficiently exhibited, and the transportability and winding property of the optical film may be insufficient. Moreover, there exists a possibility that transparency may be impaired as it is 1.0 mass% or more.

  The type of the fine particles (B) is not particularly limited, and examples thereof include inorganic fine particles, organic fine particles, and organic-inorganic composite fine particles. The organic fine particles are, for example, fine particles made of an organic cross-linked polymer such as a vinyl cross-linked polymer, and when the fine particles (B) are organic cross-linked polymer fine particles or organic-inorganic composite fine particles, the refractive index and average diameter of the fine particles. Is easy to control. On the other hand, when the fine particles (B) are inorganic fine particles, the heat resistance of the optical film of the present invention containing the fine particles is increased, and the anti-blocking property of the optical film of the present invention is high due to the high hardness of the fine particles (B). Will improve.

  The inorganic fine particles are, for example, glass particles, silica particles, and alumina particles.

  The organic crosslinked polymer fine particles include, for example, a monofunctional monomer such as methyl methacrylate and a polyfunctional monomer such as trimethylolpropane tri (meth) acrylate, allyl (meth) acrylate, and ethylene glycol di (meth) acrylate. (Meth) acrylic crosslinked fine particles obtained by suspension polymerization (see Japanese Patent No. 4034157). Styrene- (meth) acryl crosslinked fine particles obtained by further copolymerizing a styrene monomer such as styrene, α-methylstyrene, divinylbenzene or the like at the time of suspension polymerization may be used. Moreover, at least 1 sort (s) chosen from a (meth) acrylic acid monomer, a (meth) acrylic acid ester monomer, and a styrene-type monomer was obtained by carrying out emulsion polymerization, soap free emulsion polymerization, miniemulsion polymerization, dispersion polymerization, or seed polymerization ( It may be meth) acrylic crosslinked fine particles or styrene- (meth) acrylic crosslinked fine particles.

  The organic-inorganic composite fine particles are composed of an organic part and an inorganic part. The content of the inorganic part in the organic-inorganic composite fine particles is, for example, 0.5 to 90% by mass in terms of inorganic oxide, preferably 1 to 70% by mass, and more preferably 2 to 60% by mass. Here, the content in terms of inorganic oxide specifically refers to when the particles are fired at a high temperature (for example, 1000 ° C. or higher) in an oxidizing atmosphere such as in the air with respect to the weight of the organic-inorganic composite fine particles. It is a numerical value represented by the ratio of the weight of the remaining inorganic oxide.

Specific organic-inorganic composite fine particles are not particularly limited. Preferred examples include an organic polymer skeleton described in JP-A-8-81561 and a polysiloxane skeleton having organic silicon in which a silicon atom is directly chemically bonded to at least one carbon atom in the skeleton. In the structure of particles having a content of SiO ₂ constituting the polysiloxane skeleton of 25% by mass or more and polysiloxane particles having a (meth) acryloxy group described in JP-A No. 2003-183337 It is a particle comprising a vinyl polymer.

  The average particle size of the fine particles (B) is preferably 10 to 500 nm, more preferably 10 to 300 nm, and further preferably 10 to 200 nm. When the average particle size of the fine particles (B) is less than 10 nm, it becomes difficult to obtain an optical film having antiblocking properties. When the average particle diameter of the fine particles (B) exceeds 500 nm, it becomes difficult to obtain an optical film having sufficient transparency as an optical film.

  The average particle size of the fine particles (B) is determined by a laser diffraction / scattering particle size distribution measuring device (for example, LA-920, manufactured by Horiba, Ltd.) or a precision particle size distribution measuring device (for example, manufactured by Beckman Coulter, Coulter Multisizer III). ).

  The shape of the fine particles (B) is not particularly limited, and may be any shape such as a spherical shape, a needle shape, a plate shape, a scale shape, a crushed shape, a bowl shape, a bowl shape, and a confetti shape. The shape of the fine particles (B) is preferably spherical. In this case, the anti-blocking uniformity in the obtained optical film is higher.

  When the fine particles (B) are organic fine particles or organic-inorganic composite fine particles, the refractive index of the fine particles (B) is 0.98 times or more and 1.02 times or less based on the refractive index of the (meth) acrylic polymer. It is preferable that the ratio is 0.99 times or more and 1.01 times or less.

  Although it does not specifically limit as a manufacturing method of a resin film, For example, a (meth) acrylic-type polymer and microparticles | fine-particles (B), another polymer, an additive, etc. by arbitrary appropriate mixing methods. It is possible to form a film after thoroughly mixing to obtain a thermoplastic resin composition in advance. Alternatively, the (meth) acrylic polymer, the fine particles (B), and other polymers and additives may be made into separate solutions and mixed to form a uniform mixed solution, and then formed into a film. .

  In order to produce the thermoplastic resin composition, for example, the film raw material is pre-blended with any appropriate mixer such as an omni mixer, and then the obtained mixture is extrusion kneaded. In this case, the mixer used for extrusion kneading is not particularly limited, and for example, any suitable mixer such as an extruder such as a single screw extruder or a twin screw extruder or a pressure kneader may be used. Can do.

  Examples of the film forming method include any appropriate film forming method such as a solution casting method (solution casting method), a melt extrusion method, a calendar method, and a compression molding method. Among these film forming methods, the solution casting method (solution casting method) and the melt extrusion method are preferable.

  Examples of the solvent used in the solution casting method (solution casting method) include aromatic hydrocarbons such as benzene, toluene and xylene; aliphatic hydrocarbons such as cyclohexane and decalin; ethyl acetate and butyl acetate. Esters; ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; alcohols such as methanol, ethanol, isopropanol, butanol, isobutanol, methyl cellosolve, ethyl cellosolve, and butyl cellosolve; ethers such as tetrahydrofuran and dioxane; dichloromethane , Halogenated hydrocarbons such as chloroform and carbon tetrachloride; dimethylformamide; dimethyl sulfoxide and the like. These solvents may be used alone or in combination of two or more.

  Examples of the apparatus for performing the solution casting method (solution casting method) include a drum casting machine, a band casting machine, and a spin coater.

  Examples of the melt extrusion method include a T-die method and an inflation method. The molding temperature is preferably 150 to 350 ° C, more preferably 200 to 300 ° C.

  When film-forming by the above T-die method, a T-die is attached to the tip of a known single-screw extruder or twin-screw extruder, and the film extruded into a film is wound to obtain a roll-shaped film Can do. At this time, it is possible to perform uniaxial stretching by appropriately adjusting the temperature of the winding roll and adding stretching in the extrusion direction. Also, simultaneous biaxial stretching, sequential biaxial stretching, and the like can be performed by stretching the film in a direction perpendicular to the extrusion direction.

  The resin film may be either an unstretched film or a stretched film. In the case of a stretched film, either a uniaxially stretched film or a biaxially stretched film may be used. In the case of a biaxially stretched film, either a simultaneous biaxially stretched film or a sequential biaxially stretched film may be used. In the case of biaxial stretching, the mechanical strength is improved and the film performance is improved.

  The stretching temperature is preferably in the vicinity of the glass transition temperature of the resin film, specifically, preferably (glass transition temperature-30 ° C.) to (glass transition temperature + 100 ° C.), more preferably (glass transition temperature-20). ° C) to (glass transition temperature + 80 ° C). If the stretching temperature is less than (glass transition temperature-30 ° C.), a sufficient stretching ratio may not be obtained. On the other hand, if the stretching temperature exceeds (glass transition temperature + 100 ° C.), the resin composition may flow, and stable stretching may not be performed.

  The draw ratio defined by the area ratio is preferably 1.1 to 25 times, more preferably 1.3 to 10 times. There exists a possibility that it may not lead to the improvement of the toughness accompanying extending | stretching that a draw ratio is less than 1.1 times. When the draw ratio exceeds 25 times, there is a possibility that the effect of increasing the draw ratio is not recognized.

  The stretching speed is unidirectional, preferably 10 to 20,000% / min, more preferably 100 to 10,000% / min. When the stretching speed is less than 10% / min, it takes time to obtain a sufficient stretching ratio, and the production cost may increase. If the stretching speed exceeds 20,000% / min, the stretched film may be broken.

  In order to stabilize the optical isotropy and mechanical properties of the resin film, heat treatment (annealing) or the like can be performed after the stretching treatment. Arbitrary appropriate conditions can be employ | adopted for the conditions of heat processing.

  The thickness of the resin film is preferably 5 to 350 μm, more preferably 10 to 200 μm, and further preferably 20 to 100 μm. When the thickness is less than 5 μm, not only the strength is lowered, but also when the optical film of the present invention is used as a protective film for a polarizing plate, there is a risk that crimping will increase. Moreover, when the thickness exceeds 350 μm, not only the transparency is lowered, but also the moisture permeability is reduced, and when the adhesive is bonded using a water-based adhesive, the drying rate of water as the solvent may be reduced. .

  The surface tension of the resin film is preferably 40 mN / m or more, more preferably 50 mN / m or more, and further preferably 55 mN / m or more. When the surface wetting tension is at least 40 mN / m or more, the adhesive strength between the resin film and the polarizer is further improved. Any suitable surface treatment can be applied to adjust the surface wetting tension. Examples of the surface treatment include corona discharge treatment, plasma treatment, ozone spraying, ultraviolet irradiation, flame treatment, and chemical treatment. Of these, corona discharge treatment and plasma treatment are preferable.

[Urethane resin layer]
The urethane resin layer includes a urethane resin and fine particles (A). By setting the average particle size of the fine particles (A) in the urethane resin layer to 250 nm or more, blocking that occurs during winding can be effectively suppressed, and an optical film excellent in winding properties can be provided. Moreover, the urethane resin layer excellent in adhesiveness with a resin film is obtained by using a urethane resin.

  The thickness of the urethane resin layer is preferably 0.01 μm to 5 μm, more preferably 0.02 μm to 2 μm, still more preferably 0.05 μm to 1 μm, and particularly preferably 0.05 μm to 0.5 μm. is there.

  The urethane resin layer preferably functions as an easy adhesion layer. When the urethane resin layer functions as an easy-adhesion layer, the adhesiveness between the optical film of the present invention and the polarizer can be improved.

  The urethane resin is typically obtained by reacting a polyol and a polyisocyanate. The polyol is not particularly limited as long as it has two or more hydroxyl groups in the molecule, and any appropriate polyol can be adopted. For example, polyacryl polyol, polyester polyol, polyether polyol and the like can be mentioned. These can be used alone or in combination of two or more.

  The polyacryl polyol is typically obtained by copolymerizing a (meth) acrylic acid ester and a monomer having a hydroxyl group. Examples of the (meth) acrylic acid ester include methyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate, and the like. Examples of the monomer having a hydroxyl group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and 2-hydroxy (meth) acrylate. Hydroxyalkyl esters of (meth) acrylic acid such as butyl, 4-hydroxybutyl (meth) acrylate, 2-hydroxypentyl (meth) acrylate; mono (meth) acrylic acid of polyhydric alcohols such as glycerin and trimethylolpropane Examples of the ester include N-methylol (meth) acrylamide. These can be used alone or in combination of two or more.

  The polyacryl polyol may be copolymerized with other monomers in addition to the monomer components. As the other monomer, any appropriate monomer can be adopted as long as copolymerization is possible. Specifically, unsaturated monocarboxylic acids such as (meth) acrylic acid; unsaturated dicarboxylic acids such as maleic acid and anhydrides and mono- or diesters thereof; unsaturated nitriles such as (meth) acrylonitrile; (meth) Unsaturated amides such as acrylamide and N-methylol (meth) acrylamide; Vinyl esters such as vinyl acetate and vinyl propionate; Vinyl ethers such as methyl vinyl ether; α-olefins such as ethylene and propylene; Vinyl chloride and vinylidene chloride Halogenated α, β-unsaturated aliphatic monomers such as α; β-unsaturated aromatic monomers such as styrene and α-methylstyrene. These can be used alone or in combination of two or more.

  The polyester polyol is typically obtained by reacting a polybasic acid component with a polyol component. Examples of the polybasic acid component include orthophthalic acid, isophthalic acid, terephthalic acid, 1,4-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, biphenyldicarboxylic acid, tetrahydrophthalic acid and the like. Aromatic dicarboxylic acids: oxalic acid, succinic acid, malonic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, decanedicarboxylic acid, dodecanedicarboxylic acid, octadecanedicarboxylic acid, tartaric acid, alkylsuccinic acid Aliphatic dicarboxylic acids such as linolenic acid, maleic acid, fumaric acid, mesaconic acid, citraconic acid, itaconic acid; hexahydrophthalic acid, tetrahydrophthalic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, etc. The alicyclic dicar Phosphate; or acid anhydrides thereof, alkyl esters, reactive derivatives such as acid halides and the like. These can be used alone or in combination of two or more.

  Examples of the polyol component include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, pentanediol, and 1,6-hexanediol. 1,8-octanediol, 1,10-decanediol, 1-methyl-1,3-butylene glycol, 2-methyl-1,3-butylene glycol, 1-methyl-1,4-pentylene glycol, 2 -Methyl-1,4-pentylene glycol, 1,2-dimethyl-neopentyl glycol, 2,3-dimethyl-neopentyl glycol, 1-methyl-1,5-pentylene glycol, 2-methyl-1,5 -Pentylene glycol, 3-methyl-1,5-pentylene glycol, 1,2-dimethylbutylene Recall, 1,3-dimethylbutylene glycol, 2,3-dimethylbutylene glycol, 1,4-dimethylbutylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, dipropylene glycol, polypropylene glycol, 1,4-cyclohexanedimethanol, Examples include 1,4-cyclohexanediol, bisphenol A, bisphenol F, hydrogenated bisphenol A, hydrogenated bisphenol F, and the like. These can be used alone or in combination of two or more.

  The polyether polyol is typically obtained by adding an alkylene oxide to a polyhydric alcohol by ring-opening polymerization. Examples of the polyhydric alcohol include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, glycerin, trimethylolpropane, and the like. Examples of the alkylene oxide include ethylene oxide, propylene oxide, butylene oxide, styrene oxide, and tetrahydrofuran. These can be used alone or in combination of two or more.

  Examples of the polyisocyanate include tetramethylene diisocyanate, dodecamethylene diisocyanate, 1,4-butane diisocyanate, hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, and lysine. Aliphatic diisocyanates such as diisocyanate, 2-methylpentane-1,5-diisocyanate, 3-methylpentane-1,5-diisocyanate; isophorone diisocyanate, hydrogenated xylylene diisocyanate, 4,4'-cyclohexylmethane diisocyanate, 1,4 -Cycloaliphatic diisocyanate, methylcyclohexylene diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane and other alicyclic groups Isocyanate; tolylene diisocyanate, 2,2'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-diphenyldimethylmethane diisocyanate, 4,4'-dibenzyl diisocyanate, 1 , 5-naphthylene diisocyanate, xylylene diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate and other aromatic diisocyanates; dialkyldiphenylmethane diisocyanate, tetraalkyldiphenylmethane diisocyanate, α, α, α, α-tetramethylxylylene Examples include aromatic aliphatic diisocyanates such as range isocyanate. These can be used alone or in combination of two or more.

  The urethane resin preferably has a carboxyl group. By having a carboxyl group, an optical film excellent in adhesiveness with a polarizer (particularly under high temperature and high humidity) can be provided. The urethane resin having a carboxyl group can be obtained, for example, by reacting a chain extender having a free carboxyl group in addition to the polyol and the polyisocyanate. Examples of the chain extender having a free carboxyl group include dihydroxycarboxylic acid and dihydroxysuccinic acid. Examples of the dihydroxycarboxylic acid include dialkylolalkanoic acids such as dimethylolalkanoic acid (for example, dimethylolacetic acid, dimethylolbutanoic acid, dimethylolpropionic acid, dimethylolbutyric acid, dimethylolpentanoic acid). These can be used alone or in combination of two or more.

  In the production of the urethane resin, in addition to the above components, other polyols and other chain extenders can be reacted. Examples of other polyols include sorbitol, 1,2,3,6-hexanetetraol, 1,4-sorbitan, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerin, and trimethylol. Examples thereof include polyols having 3 or more hydroxyl groups such as ethane, trimethylolpropane and pentaerythritol. Examples of other chain extenders include ethylene glycol, diethylene glycol, triethylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, pentanediol, 1,6 -Glycols such as hexanediol and propylene glycol; aliphatic diamines such as ethylenediamine, propylenediamine, hexamethylenediamine, 1,4-butanediamine, and aminoethylethanolamine; isophoronediamine, 4,4'-dicyclohexylmethanediamine, etc. Alicyclic diamines; and aromatic diamines such as xylylenediamine and tolylenediamine.

  Arbitrary appropriate methods can be employ | adopted for the manufacturing method of the said urethane resin. Specific examples include a one-shot method in which the above components are reacted at once and a multi-stage method in which the components are reacted in stages. When the urethane resin has a carboxyl group, it is preferably a multistage method. This is because a carboxyl group can be easily introduced. In the production of the urethane resin, any suitable urethane reaction catalyst can be used.

  The number average molecular weight of the urethane resin is preferably 5,000 to 600,000, and more preferably 10,000 to 400,000. The acid value of the urethane resin is preferably 10 or more, more preferably 10 to 50, and particularly preferably 20 to 45. When the acid value is within such a range, the adhesion between the optical film of the present invention and the polarizer is more excellent.

  The urethane resin layer is preferably formed as a urethane composition containing a urethane resin and fine particles (A). There is no restriction | limiting in particular in the method of forming a urethane composition in a urethane resin layer, You may form by melt film formation and may form by solution film formation, More preferably, you may form by solution film formation. preferable. The urethane composition that can be used for solution casting is more preferably aqueous. The water system is superior to the solvent system in terms of environment and workability.

  When the urethane composition is water-based, a neutralizing agent is preferably used in the production of the urethane resin. By using a neutralizing agent, the stability of the urethane resin in water is improved. Examples of the neutralizing agent include ammonia, N-methylmorpholine, triethylamine, dimethylethanolamine, methyldiethanolamine, triethanolamine, morpholine, tripropylamine, ethanolamine, triisopropanolamine, 2-amino-2-methyl-1 -Propanol etc. are mentioned. These can be used alone or in combination of two or more.

  When the urethane composition is water-based, an organic solvent that is inert to the polyisocyanate and is compatible with water is preferably used in the production of the urethane resin. Examples of the organic solvent include ester solvents such as ethyl acetate, butyl acetate, and ethyl cellosolve acetate; ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; ether solvents such as dioxane, tetrahydrofuran, and propylene glycol monomethyl ether. A solvent etc. are mentioned. These may be used alone or in combination of two or more.

  As the fine particles (A) contained in the urethane resin layer, any appropriate fine particles can be used as long as the average particle diameter is 250 nm or more. Water-dispersible fine particles are preferable. Specifically, both inorganic fine particles and organic fine particles can be used. Examples of the inorganic fine particles include inorganic oxides such as silica, titania, alumina, zirconia, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate, calcium phosphate, and the like. Can be mentioned. Examples of the organic fine particles include silicone resins, fluorine resins, (meth) acrylic resins, and the like. Among these, silica is preferable. It is possible to further improve the blocking inhibition ability, and has excellent transparency, no haze, and no coloration. Therefore, when the optical film of the present invention is used as a polarizer protective film, the optical properties of the obtained polarizing plate are improved. This is because the effect is smaller. Further, since silica has good dispersibility and dispersion stability in the urethane composition, it is more excellent in workability when forming the urethane resin layer. Furthermore, silica is excellent in adhesiveness with the resin film.

  The average particle diameter of the fine particles (A) is preferably 250 nm to 1000 nm, more preferably 280 to 500 nm, and further preferably 280 to 400 nm. By using fine particles with such a particle size, irregularities are appropriately formed on the surface of the urethane resin layer, and the frictional force at the contact surface between the resin film and the urethane resin layer and / or the urethane resin layer is effectively reduced. be able to. If the average particle size is less than 250 nm, the blocking inhibiting ability may be insufficient, and if the average particle size is larger than 1000 nm, the transparency of the optical film may be lowered.

  The average particle diameter of the fine particles (A) can be determined in the same manner as the fine particles (B).

  When the urethane composition is aqueous, the fine particles (A) are preferably blended as an aqueous dispersion. Specifically, when silica is employed as the fine particles (A), it is preferably blended as colloidal silica. A commercial item can be used as it is as colloidal silica. Commercially available products include, for example, Quatron PL series manufactured by Fuso Chemical Industry Co., Ltd., Snowtex series manufactured by Nissan Chemical Industry Co., Ltd., Aeroerosp series and AEROSIL series manufactured by Nippon Aerosil Co., Ltd., manufactured by Nippon Shokubai Co., Ltd. The Sea Hoster series etc. can be mentioned.

  The urethane composition preferably contains a crosslinking agent. Arbitrary appropriate crosslinking agents can be employ | adopted for the said crosslinking agent. Specifically, when the urethane resin has a carboxyl group, the crosslinking agent preferably includes a polymer having a group capable of reacting with the carboxyl group. Examples of the group that can react with a carboxyl group include an organic amino group, an oxazoline group, an epoxy group, and a carbodiimide group. Preferably, the crosslinking agent has an oxazoline group. Among these, the crosslinking agent having an oxazoline group has a long pot life at the time of mixing with the urethane resin, and has a good workability because the crosslinking reaction proceeds by heating.

  Any appropriate polymer can be adopted as the polymer. Examples thereof include acrylic polymers and styrene / acrylic polymers. An acrylic polymer is preferable. By using an acrylic polymer, the adhesion to the polarizer can be further improved. In addition, it is stably compatible with an aqueous urethane composition and can be well crosslinked with the urethane resin.

  The urethane composition can further include any appropriate additive. Examples of the additive include a dispersion stabilizer, a thixotropic agent, an antioxidant, an ultraviolet absorber, an antifoaming agent, a thickener, a dispersant, a surfactant, a catalyst, a filler, a lubricant, and an antistatic agent. It is done.

  As described above, the urethane composition is preferably aqueous. The concentration of the urethane resin in the urethane composition is preferably 1.5 to 15% by mass, and more preferably 2 to 10% by mass. It is because it is excellent in workability | operativity at the time of urethane resin layer formation as it is the said range. The content of the crosslinking agent (solid content) in the urethane composition is preferably 1 to 30 parts by mass, more preferably 3 to 20 parts by mass with respect to 100 parts by mass of the urethane resin (solid content). By setting it as 1 mass part or more, the adhesiveness of the optical film of this invention and a polarizer can be improved. On the other hand, by setting it as 30 mass parts or less, it can suppress that a phase difference expresses in a urethane resin layer. The content of fine particles in the urethane resin layer is preferably 0.1% by mass to 2% by mass, and more preferably 0.2% by mass to 0.5% by mass. By setting in such a range, it is possible to appropriately reduce the frictional force on the contact surface between the resin film and the urethane resin layer and / or the urethane resin layer by appropriately forming irregularities on the surface of the urethane resin layer. it can. As a result, it can be set as the optical film which was further excellent in blocking suppression ability. Moreover, the influence which it has on the optical characteristic of a polarizing plate can be suppressed more.

  The friction coefficient between the resin film and the urethane resin layer is preferably 0.1 to 0.6, and more preferably 0.2 to 0.4.

[Optical film]
The optical film of the present invention is an optical film having a resin film containing a (meth) acrylic polymer and a urethane resin layer containing a urethane resin and fine particles (A), and the average particle of the fine particles (A) The diameter is not particularly limited as long as the diameter is 250 nm or more and the resin film contains fine particles (B).

  The thickness of the optical film of the present invention is preferably 1 μm to 350 μm, more preferably 5 μm to 250 μm, further preferably 10 μm to 150 μm, and particularly preferably 20 μm to 100 μm.

  In the optical film of the present invention, the urethane resin layer may be directly laminated on the resin film, or may be laminated via another layer.

  The internal haze of the optical film of the present invention is preferably 0.5% or less, more preferably 0.2% or less, and further preferably 0.1% or less. If the internal haze is larger than 0.5%, the transmittance is lowered, and therefore it may not be suitable for use in an image display device or the like.

  In the optical film of the present invention, it is preferable that the average particle size of the fine particles (A) contained in the urethane resin layer is larger than the average particle size of the fine particles (B) contained in the resin film. Since the average particle diameter of the fine particles (A) contained in the urethane resin layer is large, the effect of suppressing blocking can be increased. Further, by reducing the average particle diameter of the fine particles (B), the internal haze of the optical film can be reduced, and an optical film having more excellent transparency can be obtained.

  In the optical film of the present invention, since the resin film and the urethane resin layer each contain fine particles, the film is less likely to be damaged at the time of film formation, and the effect of suppressing blocking when formed into a roll shape. Will improve.

  Any appropriate method can be adopted as a method for producing the optical film of the present invention. Hereinafter, one embodiment will be described. For example, the urethane resin layer is formed in advance on one side of the resin film. The urethane resin layer is typically formed by applying the urethane composition to one side of a resin film and drying it. Any appropriate method can be adopted as a method of applying the urethane composition. Examples thereof include a bar coating method, a roll coating method, a gravure coating method, a rod coating method, a slot orifice coating method, a curtain coating method, and a fountain coating method. The drying temperature is typically 50 ° C. or higher, preferably 90 ° C. or higher, more preferably 110 ° C. or higher. By setting the drying temperature in such a range, when the optical film of the present invention is used as a polarizer protective film, a polarizing plate excellent in color resistance (particularly under high temperature and high humidity) can be provided. . The upper limit of the drying temperature is preferably 200 ° C. or lower, more preferably 180 ° C. or lower.

As described above, surface treatment can be performed on at least one side of the resin film (for example, the side on which the urethane resin layer is formed). In this case, it is preferable to perform a surface treatment before forming the urethane resin layer. The surface treatment is preferably corona discharge treatment or plasma treatment. By performing the corona discharge treatment, the adhesion and adhesion between the optical film of the present invention and the polarizer can be further improved. The corona discharge treatment is performed under any appropriate conditions. For example, the corona discharge electron irradiation amount is preferably 50 to 150 W / m ² / min, more preferably 70 to 100 W / m ² / min.

  In addition, when the said resin film is a stretched film, the said extending | stretching process may be performed before formation of a urethane resin layer, and may be performed after formation of a urethane resin layer. Preferably, the urethane composition is applied to a resin film and then stretched. This is because the film stretching process and the urethane composition drying can be carried out simultaneously.

  Various functional coating layers may be formed on the surface of the optical film of the present invention as necessary. Functional coating layers include, for example, antistatic layers, adhesive layers, adhesive layers, antiglare (non-glare) layers, antifouling layers such as photocatalyst layers, antireflection layers, hard coat layers, ultraviolet shielding layers, and heat ray shielding. Layers, electromagnetic wave shielding layers, gas barrier layers, and the like.

  Although the use of the optical film of the present invention is not particularly limited, it can be suitably used as an optical member due to its high transparency and heat resistance. The optical member is, for example, an optical protective film, specifically, a protective film for various optical disk (VD, CD, DVD, MD, LD, etc.) substrates, and a polarized light included in an image display device such as a liquid crystal display (LCD). It is a polarizer protective film used for a board. The optical film of the present invention may be used as an optical film such as a retardation film, a viewing angle compensation film, a light diffusion film, a reflection film, an antireflection film, an antiglare film, a brightness enhancement film, and a conductive film for a touch panel.

Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited to these. In the following description, for convenience, “part by mass” may be simply referred to as “part”, and “liter” may be simply referred to as “L”. The sample for measuring film properties was obtained from the center in the width direction.
For convenience, the following abbreviations are used in the examples.
MMA: Methyl methacrylate MHMA: Methyl 2- (hydroxymethyl) acrylate <Glass transition temperature>
The glass transition temperature (Tg) of each sample was determined in accordance with JIS K7121 regulations. Specifically, using a differential scanning calorimeter (manufactured by Rigaku, DSC-8230), a sample of about 10 mg was heated from a normal temperature to 200 ° C. at a heating rate of 20 ° C./min in a nitrogen gas atmosphere. It calculated by the starting point method from the DSC curve. Α-alumina was used as a reference.

<Weight average molecular weight>
The weight average molecular weight was determined by gel permeation chromatography (GPC) under the following conditions.
System: GPC system HLC-8220 manufactured by Tosoh Corporation
Developing solvent: Chloroform (made by Wako Pure Chemical Industries, special grade), flow rate: 0.6 ml / min Standard sample: TSK standard polystyrene (manufactured by Tosoh Corporation, PS-oligomer kit)
Measurement side column configuration: guard column (manufactured by Tosoh Corp., TSKguardcolumn SuperHZ-L), separation column (manufactured by Tosoh Corp., TSKgel SuperHZM-M) 2 series connection reference side column configuration: reference column (manufactured by Tosoh Corp., TSKgel SuperH-RC) )
<Internal haze>
Using a quartz cell, the film was immersed in decalin and measured using a turbidimeter (NDH 5000, manufactured by Nippon Denshoku Industries Co., Ltd.).
<Average particle size>
The average particle size of the fine particles was measured using a precision particle size distribution measuring device (Beckman Coulter, Coulter Multisizer III).

<Thickness of film>
Measurement was performed using a Digimatic Micrometer (manufactured by Mitutoyo Corporation).

<Film transportability>
After applying the urethane resin layer, the scratches on the film surface when passing through the feeding roll in the film transport system were visually confirmed.
○: No scratch ×: Scratch <Film winding property>
The optical film laminated with the urethane resin layer was wound into a roll, and the state of the film after 24 hours was visually observed.
○: Wrinkles, no breakage ×: Wrinkles, breakage <Adhesiveness>
A polyvinyl alcohol resin (average polymerization degree 1200) was dissolved in pure water to obtain an adhesive composition having a solid content of 4%. The obtained adhesive composition was applied to the easy-adhesion layer side of the optical film so that the thickness after drying was 50 nm, and the film was obtained by putting in an 80 ° C. hot air dryer for 5 minutes and drying. It was. The film obtained above was subjected to a cross cut test in accordance with JIS K5400 3.5. Specifically, a 1 mm square grid cut was made with a sharp blade on the adhesive layer surface of the test sample, and then a cellophane tape having a width of 25 mm in accordance with JIS Z1522 was adhered with a wooden spatula. Thereafter, the cellophane tape was peeled off, and the state of the layer was observed. The evaluation criteria are as follows.
○: No peeling was confirmed ×: Peeling was confirmed [Production Example 1]
MMA 40 parts, MHMA 10 parts, toluene 50 parts, ADK STAB 2112 (manufactured by ADEKA) 0.025 part was charged into a reaction kettle equipped with a stirrer, temperature sensor, cooling pipe, and nitrogen introduction pipe, and nitrogen was passed through this at 105 ° C. When the mixture was heated to reflux and refluxed, 0.05 part of tertiary amyl peroxyisonononanoate (manufactured by Atofina Yoshitomi, trade name: Luperox 570) was added as an initiator, and at the same time, tertiary amyl peroxyisonononate 0. While dropping 1 part over 3 hours, solution polymerization was performed under reflux at about 105 to 110 ° C., and further aging was performed for 4 hours.

  To the obtained polymer solution, 0.05 part of 2-ethylhexyl phosphate (manufactured by Sakai Chemicals, trade name: Phoslex A-8) was added, and a cyclization condensation reaction was performed at 90 to 105 ° C. under reflux for 2 hours. It was. Next, the obtained polymer solution was heated to 240 ° C. through a heat exchanger, barrel temperature 240 ° C., degree of vacuum 13.3 to 400 hPa (10 to 300 mmHg), rear vent number 1 and fore vent number 4 A side feeder is provided between the third vent and the fourth vent (referred to as the first, second, third, and fourth vents from the upstream side), and a leaf disk type polymer filter (filtered at the tip) It was introduced into a vent type screw twin screw extruder (φ = 44, L / D = 52) having a precision of 5 μm) at a processing speed of 75 parts / hour in terms of resin amount, and devolatilization was performed. At that time, a separately prepared mixed solution of antioxidant / cyclization catalyst deactivator was added at a rate of 1.13 parts / hour from the back of the first vent, and 1.13 parts / hour of ion-exchanged water. Were charged from the back of the second and third vents, respectively. Antioxidant / cyclization catalyst deactivator mixed solution, antioxidant / cyclization catalyst deactivator mixed solution, 5 parts of antioxidant (manufactured by Ciba Specialty Chemicals, Irganox 1010), A solution in which 46 parts of zinc octylate (manufactured by Nippon Kagaku Sangyo Co., Ltd., 3.6% of Nikka octix zinc) was dissolved in 62 parts of toluene was used as a quencher. Further, from the side feeder, pellets of a styrene-acrylonitrile copolymer (the ratio of styrene / acrylonitrile is 73 mass% / 27 mass%, weight average molecular weight 220,000) are 25 parts / hour, and spherical fine particles (manufactured by Nippon Shokubai Co., Ltd.) Sea Hoster KE-P10, average particle size 100 nm) was charged at a loading speed of 0.10 parts / hour.

By the devolatilization operation, resin pellets containing fine particles and an acrylic polymer were obtained. The pellets had a glass transition temperature of 122 ° C. and a weight average molecular weight of 151,000. The obtained pellets were melt-extruded from a T-die at 280 ° C. using a single screw extruder and discharged onto a 110 ° C. cooling roll to form a film having a thickness of 100 μm. Next, the film formed was stretched in the direction perpendicular to the direction in which the film was stretched so that the stretch ratio was 2.0 times, whereby a stretched film 1 was obtained.
[Production Example 2]
MMA 40 parts, MHMA 10 parts, toluene 50 parts, ADK STAB 2112 (manufactured by ADEKA) 0.025 part was charged into a reaction kettle equipped with a stirrer, temperature sensor, cooling pipe, and nitrogen introduction pipe, and nitrogen was passed through this at 105 ° C. When the mixture was heated to reflux and refluxed, 0.05 part of tertiary amyl peroxyisonononanoate (manufactured by Atofina Yoshitomi, trade name: Luperox 570) was added as an initiator, and at the same time, tertiary amyl peroxyisonononate 0. While dropping 1 part over 3 hours, solution polymerization was performed under reflux at about 105 to 110 ° C., and further aging was performed for 4 hours.

  To the obtained polymer solution, 0.05 part of 2-ethylhexyl phosphate (manufactured by Sakai Chemicals, trade name: Phoslex A-8) was added, and a cyclization condensation reaction was performed at 90 to 105 ° C. under reflux for 2 hours. It was. Next, the obtained polymer solution was heated to 240 ° C. through a heat exchanger, barrel temperature 240 ° C., degree of vacuum 13.3 to 400 hPa (10 to 300 mmHg), rear vent number 1 and fore vent number 4 A side feeder is provided between the third vent and the fourth vent (referred to as the first, second, third, and fourth vents from the upstream side), and a leaf disk type polymer filter (filtered at the tip) It was introduced into a vent type screw twin screw extruder (φ = 44, L / D = 52) having a precision of 5 μm) at a processing speed of 75 parts / hour in terms of resin amount, and devolatilization was performed. At that time, a separately prepared mixed solution of antioxidant / cyclization catalyst deactivator was added at a rate of 1.13 parts / hour from the back of the first vent, and ion exchange water was supplied from the back of the second vent. At a charging speed of 1.13 parts / hour, a fine particle dispersion (manufactured by Nippon Shokubai, Epostor MX-50W, average particle diameter 0.06 μm, solid content 4.8%) is 2.08 parts / from the back of the third vent. Each was loaded at the same loading speed. Antioxidant / cyclization catalyst deactivator mixed solution, antioxidant / cyclization catalyst deactivator mixed solution, 5 parts of antioxidant (manufactured by Ciba Specialty Chemicals, Irganox 1010), A solution in which 46 parts of zinc octylate (manufactured by Nippon Kagaku Sangyo Co., Ltd., 3.6% of Nikka octix zinc) was dissolved in 62 parts of toluene was used as a quencher. Moreover, pellets of a styrene-acrylonitrile copolymer (the ratio of styrene / acrylonitrile is 73% by mass / 27% by mass, weight average molecular weight 220,000) were charged from the side feeder at a rate of 25 parts / hour.

By the devolatilization operation, resin pellets containing fine particles and an acrylic polymer were obtained. The pellets had a glass transition temperature of 122 ° C. and a weight average molecular weight of 151,000. The obtained pellets were melt-extruded from a T-die at 280 ° C. using a single screw extruder and discharged onto a 110 ° C. cooling roll to form a film having a thickness of 100 μm. Next, the film formed was stretched in the direction perpendicular to the direction in which the film was stretched so that the stretch ratio was 2.0 times to obtain a stretched film 2.
[Production Example 3]
MMA 40 parts, MHMA 10 parts, toluene 50 parts, ADK STAB 2112 (manufactured by ADEKA) 0.025 part was charged into a reaction kettle equipped with a stirrer, temperature sensor, cooling pipe, and nitrogen introduction pipe, and nitrogen was passed through this at 105 ° C. When the mixture was heated to reflux and refluxed, 0.05 part of tertiary amyl peroxyisonononanoate (manufactured by Atofina Yoshitomi, trade name: Luperox 570) was added as an initiator, and at the same time, tertiary amyl peroxyisonononate 0. While dropping 1 part over 3 hours, solution polymerization was performed under reflux at about 105 to 110 ° C., and further aging was performed for 4 hours.

  To the obtained polymer solution, 0.05 part of 2-ethylhexyl phosphate (manufactured by Sakai Chemicals, trade name: Phoslex A-8) was added, and a cyclization condensation reaction was performed at 90 to 105 ° C. under reflux for 2 hours. It was. Next, the obtained polymer solution was heated to 240 ° C. through a heat exchanger, barrel temperature 240 ° C., degree of vacuum 13.3 to 400 hPa (10 to 300 mmHg), rear vent number 1 and fore vent number 4 A side feeder is provided between the third vent and the fourth vent (referred to as the first, second, third, and fourth vents from the upstream side), and a leaf disk type polymer filter (filtered at the tip) It was introduced into a vent type screw twin screw extruder (φ = 44, L / D = 52) having a precision of 5 μm) at a processing speed of 75 parts / hour in terms of resin amount, and devolatilization was performed. At that time, a separately prepared mixed solution of antioxidant / cyclization catalyst deactivator was added at a rate of 1.13 parts / hour from the back of the first vent, and 1.13 parts / hour of ion-exchanged water. Were charged from the back of the second and third vents, respectively. Antioxidant / cyclization catalyst deactivator mixed solution, antioxidant / cyclization catalyst deactivator mixed solution, 5 parts of antioxidant (manufactured by Ciba Specialty Chemicals, Irganox 1010), A solution in which 46 parts of zinc octylate (manufactured by Nippon Kagaku Sangyo Co., Ltd., 3.6% of Nikka octix zinc) was dissolved in 62 parts of toluene was used as a quencher. Further, from the side feeder, pellets of a styrene-acrylonitrile copolymer (the ratio of styrene / acrylonitrile is 73 mass% / 27 mass%, weight average molecular weight 220,000) are 25 parts / hour, and spherical fine particles (manufactured by Nippon Shokubai Co., Ltd.) Sea Hoster KE-P30, average particle size of 0.30 μm) was charged at a loading speed of 0.10 parts / hour.

By the devolatilization operation, resin pellets containing fine particles and an acrylic polymer were obtained. The pellets had a glass transition temperature of 122 ° C. and a weight average molecular weight of 151,000. The obtained pellets were melt-extruded from a T-die at 280 ° C. using a single screw extruder and discharged onto a 110 ° C. cooling roll to form a film having a thickness of 100 μm. Next, the film formed was stretched in the direction perpendicular to the direction in which the film was stretched so that the stretch ratio was 2.0 times to obtain a stretched film 3.
[Production Example 4]
MMA 40 parts, MHMA 10 parts, toluene 50 parts, ADK STAB 2112 (manufactured by ADEKA) 0.025 part was charged into a reaction kettle equipped with a stirrer, temperature sensor, cooling pipe, and nitrogen introduction pipe, and nitrogen was passed through this at 105 ° C. When the mixture was heated to reflux and refluxed, 0.05 part of tertiary amyl peroxyisonononanoate (manufactured by Atofina Yoshitomi, trade name: Luperox 570) was added as an initiator, and at the same time, tertiary amyl peroxyisonononate 0. While dropping 1 part over 3 hours, solution polymerization was performed under reflux at about 105 to 110 ° C., and further aging was performed for 4 hours.

  To the obtained polymer solution, 0.05 part of 2-ethylhexyl phosphate (manufactured by Sakai Chemicals, trade name: Phoslex A-8) was added, and a cyclization condensation reaction was performed at 90 to 105 ° C. under reflux for 2 hours. It was. Next, the obtained polymer solution was heated to 240 ° C. through a heat exchanger, barrel temperature 240 ° C., degree of vacuum 13.3 to 400 hPa (10 to 300 mmHg), rear vent number 1 and fore vent number 4 A side feeder is provided between the third vent and the fourth vent (referred to as the first, second, third, and fourth vents from the upstream side), and a leaf disk type polymer filter (filtered at the tip) It was introduced into a vent type screw twin screw extruder (φ = 44, L / D = 52) having a precision of 5 μm) at a processing speed of 75 parts / hour in terms of resin amount, and devolatilization was performed. At that time, a separately prepared mixed solution of antioxidant / cyclization catalyst deactivator was added at a rate of 1.13 parts / hour from the back of the first vent, and 1.13 parts / hour of ion-exchanged water. Were charged from the back of the second and third vents, respectively. Antioxidant / cyclization catalyst deactivator mixed solution, antioxidant / cyclization catalyst deactivator mixed solution, 5 parts of antioxidant (manufactured by Ciba Specialty Chemicals, Irganox 1010), A solution in which 46 parts of zinc octylate (manufactured by Nippon Kagaku Sangyo Co., Ltd., 3.6% of Nikka octix zinc) was dissolved in 62 parts of toluene was used as a quencher. Moreover, pellets of a styrene-acrylonitrile copolymer (the ratio of styrene / acrylonitrile is 73% by mass / 27% by mass, weight average molecular weight 220,000) were charged from the side feeder at a rate of 25 parts / hour.

By the devolatilization operation, resin pellets containing an acrylic polymer not containing fine particles were obtained. The pellets had a glass transition temperature of 122 ° C. and a weight average molecular weight of 151,000. The obtained pellets were melt-extruded from a T-die at 280 ° C. using a single screw extruder and discharged onto a 110 ° C. cooling roll to form a film having a thickness of 100 μm. Next, the film formed was stretched in the direction perpendicular to the direction in which the film was stretched so that the stretching ratio was 2.0, whereby a stretched film 4 was obtained.
[Example 1]
(Formation of urethane resin layer)
20 parts urethane resin (Daiichi Kogyo Seiyaku, Superflex 210, solid content 35%), 0.09 part fine particle dispersion (Nippon Shokubai Co., Ltd., Seahoster KE-W30, average particle size 280 nm, solid content 20%) and 80 parts of pure water was mixed to obtain a urethane composition.

The obtained urethane composition was applied to one side of the stretched film 1 obtained in Production Example 1 using a coating tester so that the thickness after drying was 270 nm, and dried at 100 ° C. for 2 minutes, Optical film 1 in which a urethane resin layer was laminated on one side of stretched film 1 was created.
[Example 2]
An optical film 2 was prepared in the same manner as in Example 1 except that Seahoster KE-W30 was changed to Epostor MX-200W (manufactured by Nippon Shokubai, average particle diameter 350 nm, solid content 20%) as a fine particle dispersion.
Example 3
An optical film 3 was prepared in the same manner as in Example 1 except that the stretched film 1 was changed to the stretched film 2 obtained in Production Example 2.
[Comparative Example 1]
The stretched film 1 was changed to the stretched film 3 obtained in Production Example 3, and an optical film 4 was prepared in the same manner as in Example 1 except that the following urethane composition was used when forming the urethane resin layer.
(Preparation of urethane composition)
20 parts of urethane-based resin (Daiichi Kogyo Seiyaku, Superflex 210, solid content 35%) and 80 parts of pure water were mixed to obtain a urethane composition.
[Comparative Example 2]
An optical film 5 was prepared in the same manner as in Example 1 except that the stretched film 1 was changed to the stretched film 4 obtained in Production Example 4.
[Comparative Example 3]
An optical film 6 was prepared in the same manner as in Example 1 except that the following easy-adhesion composition was used in forming the easy-adhesion layer.
(Preparation of easy adhesion composition)
20 parts of urethane resin (Daiichi Kogyo Seiyaku Co., Ltd., Superflex 210, solid content 35%) and 80 parts of pure water were mixed to obtain an easy-adhesive composition.
[Comparative Example 4]
In forming the urethane resin layer, an optical film 7 was prepared in the same manner as in Example 1 except that the following urethane composition was used.
(Preparation of urethane composition)
20 parts urethane resin (Daiichi Kogyo Seiyaku, Superflex 210, solid content 35%), 0.12 part fine particle dispersion (Nippon Shokubai, Seahoster KE-W10, average particle size 110 nm, solid content 15%) and 80 parts of pure water was mixed to obtain a urethane composition.
[Comparative Example 5]
MMA 40 parts, MHMA 10 parts, toluene 50 parts, ADK STAB 2112 (manufactured by ADEKA) 0.025 part was charged into a reaction kettle equipped with a stirrer, temperature sensor, cooling pipe, and nitrogen introduction pipe, and nitrogen was passed through this at 105 ° C. When the mixture was heated to reflux and refluxed, 0.05 part of tertiary amyl peroxyisonononanoate (manufactured by Atofina Yoshitomi, trade name: Luperox 570) was added as an initiator, and at the same time, tertiary amyl peroxyisonononate 0. While dropping 1 part over 3 hours, solution polymerization was performed under reflux at about 105 to 110 ° C., and further aging was performed for 4 hours.

  To the obtained polymer solution, 0.05 part of 2-ethylhexyl phosphate (manufactured by Sakai Chemicals, trade name: Phoslex A-8) was added, and a cyclization condensation reaction was performed at 90 to 105 ° C. under reflux for 2 hours. It was. Next, the obtained polymer solution was heated to 240 ° C. through a heat exchanger, barrel temperature 240 ° C., degree of vacuum 13.3 to 400 hPa (10 to 300 mmHg), rear vent number 1 and fore vent number 4 A side feeder is provided between the third vent and the fourth vent (referred to as the first, second, third, and fourth vents from the upstream side), and a leaf disk type polymer filter (filtered at the tip) It was introduced into a vent type screw twin screw extruder (φ = 44, L / D = 52) having a precision of 5 μm) at a processing speed of 75 parts / hour in terms of resin amount, and devolatilization was performed. At that time, a separately prepared mixed solution of antioxidant / cyclization catalyst deactivator was added at a rate of 1.13 parts / hour from the back of the first vent, and 1.13 parts / hour of ion-exchanged water. Were charged from the back of the second and third vents, respectively. Antioxidant / cyclization catalyst deactivator mixed solution, antioxidant / cyclization catalyst deactivator mixed solution, 5 parts of antioxidant (manufactured by Ciba Specialty Chemicals, Irganox 1010), A solution in which 46 parts of zinc octylate (manufactured by Nippon Kagaku Sangyo Co., Ltd., 3.6% of Nikka octix zinc) was dissolved in 62 parts of toluene was used as a quencher. Further, from the side feeder, pellets of a styrene-acrylonitrile copolymer (the ratio of styrene / acrylonitrile is 73 mass% / 27 mass%, weight average molecular weight 220,000) are 25 parts / hour, and spherical fine particles (manufactured by Nippon Shokubai Co., Ltd.) Seahoster KE-P30, average particle diameter of 300 nm) was charged at a charging speed of 0.30 parts / hour.

  By the devolatilization operation, resin pellets containing fine particles and an acrylic polymer were obtained. The pellets had a glass transition temperature of 122 ° C. and a weight average molecular weight of 151,000. The obtained pellets were melt-extruded from a T-die at 280 ° C. using a single screw extruder and discharged onto a 110 ° C. cooling roll to form a film having a thickness of 100 μm. Next, the film formed was stretched in the direction perpendicular to the direction in which the film was stretched so that the stretch ratio was 2.0 times to obtain an optical film 8.

  Evaluation was performed about the optical film obtained by each Example and the comparative example. The evaluation results are shown in Table 1.

The optical film of the present invention is excellent in transportability and suppression of blocking, and can be suitably used for applications as an optical member such as a liquid crystal display (LCD) and an organic display (OLED).

1 is a schematic cross-sectional view of an optical film according to one preferred embodiment of the present invention.

1: Optical film 11: Resin film 12: Urethane resin layer

Claims (7)

  An optical film having a resin film containing a (meth) acrylic polymer and a urethane resin layer containing a urethane resin and fine particles (A), wherein the average particle size of the fine particles (A) is 250 nm or more, The optical film, wherein the resin film contains fine particles (B).   The optical film according to claim 1, wherein the (meth) acrylic polymer has a ring structure in the main chain.   The optical film according to claim 1, wherein the resin film contains a styrene polymer.   Content of microparticles | fine-particles (A) in the said urethane resin layer is 0.05 mass% or more and 2.0 mass% or less, The optical film of any one of Claim 1 to 3 characterized by the above-mentioned.   5. The optical film according to claim 1, wherein an average particle size of the fine particles (A) is larger than an average particle size of the fine particles (B).   6. The optical film according to claim 1, wherein an average particle size of the fine particles (B) is 10 nm or more and 500 nm or less.   The optical film according to any one of claims 1 to 6, wherein the content of the fine particles (B) in the resin film is 0.01% by mass or more and 1.0% by mass or less.

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