JP2006162748A - Polarizer protection film and polarizing plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polarizer protection film which, is less colored to have a high light transmittance and is superior in optical characteristics to have a small haze, or the like, and has a satisfactory heat resistance and low water absorptivity and is superior in moisture permeability, and a polarizing plate consisting of the polarizer protection film. <P>SOLUTION: The polarizer protection film is formed from fumaric acid diester having ≥50 mol% specific fumaric acid diester residue unit and ≥10000 number-average molecular weight expressed in terms of standard polystyrene, which is obtained by gel permeation chromatography, wherein the thickness is 10 to 250μm and saturated water absorption at 23°C is ≤4% and moisture permeability when measured on condition of 40°C 90%Rh is ≥70g/m<SP>2</SP>24h, and the polarizing plate comprises the polarizer protection film. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention is a fumaric acid diester type that is excellent in optical properties such as little coloring, high light transmittance, low haze, etc., good mechanical strength and heat resistance, low water absorption, and excellent moisture permeability. The present invention relates to a polarizer protective film made of a resin and a polarizing plate.

  The polarizing plate is a material having a function of transmitting only light having a specific vibration direction and shielding other light, and is widely used as one of components constituting a liquid crystal display device, for example. As such a polarizing plate, what has the structure on which the polarizer and the protective film were laminated | stacked is generally used. The polarizer has a function of transmitting only light having a specific vibration direction. For example, a polyvinyl alcohol (hereinafter referred to as PVA) film is stretched and dyed with iodine or a dichroic dye. The film is generally used. Recently, a coating-type polarizer is also used. The protective film has a function of holding a polarizer and imparting practical strength to the entire polarizing plate. For example, a triacetyl cellulose (hereinafter referred to as TAC) film is generally used. ing. TAC film has excellent properties as a polarizer protective film because it has excellent optical uniformity such as good transparency and low birefringence, practical heat resistance and excellent mechanical strength. Yes. In addition, because of its high moisture permeability, it is generally used as a polarizer protective film because it has good processability such as excellent moisture permeability of PVA and adhesive when bonded to a polarizer such as PVA (for example, (See Patent Document 1). However, since the TAC film has high water absorption, there are problems in the performance degradation of the polarizer, dimensional stability due to water absorption, and the like.

  Attempts have been made to improve dimensional stability by using, as a polarizer protective film, a film material having a smaller water absorption rate than a conventional TAC film. However, a polycarbonate film or polyethylene terephthalate film having a small water absorption has a problem that the photoelastic constant is large and the phase difference is changed by the action of external stress, so that the performance as a polarizing plate is deteriorated. Recently, a cyclic polyolefin resin film having a small water absorption and a small photoelastic constant has been used as a polarizer protective film (see, for example, Patent Documents 2 and 3). However, the cyclic polyolefin-based resin film has a low water absorption, but also has a low moisture permeability. Therefore, when sticking a polarizer such as PVA, moisture loss in the PVA is deteriorated, resulting in poor bonding such as swelling and bubbles. There is a problem that occurs. In addition, there are problems such as the film being brittle and being deteriorated by sebum.

  A fumaric acid diester resin was discovered by Otsu et al. In 1981 (see, for example, Non-Patent Document 1). Further, an optical material made of a fumaric acid diester resin is disclosed, and an optical lens, a prism lens, an optical fiber, and the like are described (for example, see Patent Documents 4 and 5). Furthermore, a polymer alignment film substrate for a liquid crystal display using a monomolecular film made of a fumaric acid diester resin (for example, see Patent Document 6) is disclosed, and a method for producing an ultrathin film made of a fumaric acid diester resin is disclosed. Also discloses applications such as electrical elements, patterning, microlithography, and optical elements (optical waveguides, binder resins for nonlinear tertiary elements) (see, for example, Patent Document 7). However, in the prior art, a polarizer protective film and a polarizing plate made of a fumaric acid diester resin having a specific structure and characteristics have not been proposed.

Radical polymerization handbook (page 314), ST Japanese Patent Laid-Open No. 07-120617 Japanese Patent Laid-Open No. 05-212828 Japanese Patent Laid-Open No. 06-0511117 Japanese Patent Laid-Open No. 61-028513 JP 61-034007 A Japanese Patent Laid-Open No. 02-214731 Japanese Patent Laid-Open No. 02-269130

  An object of the present invention is to provide a polarizer protective film having excellent optical properties, good heat resistance and mechanical strength, low water absorption, and excellent moisture permeability, and a polarizing plate comprising the same.

  As a result of intensive studies in view of the above problems, the present inventors have a specific fumaric acid diester residue unit of 50 mol% or more, and the number average molecular weight in terms of standard polystyrene determined by gel permeation chromatography is 10,000. A film made of the above fumaric acid diester resin and having a thickness of 10 to 250 μm is excellent in optical properties, has good mechanical strength and heat resistance, has a low water absorption rate, and has excellent moisture permeability. It discovered that it became a film and a polarizing plate which consists of it, and came to complete this invention.

That is, the present invention comprises a fumaric acid diester residue unit represented by the general formula (1) of 50 mol% or more, and a fumaric acid having a number average molecular weight of 10,000 or more in terms of standard polystyrene determined by gel permeation chromatography. Polarized light comprising an acid diester resin, having a thickness of 10 to 250 μm, a saturated water absorption at 23 ° C. of 4% or less, and a moisture permeability measured at 40 ° C. and 90% Rh of 70 g / m ² · 24 h or more. The present invention relates to a child protective film and a polarizing plate comprising the same.

（１）
（ここで、Ｒ_１、Ｒ_２はそれぞれ独立して炭素数１〜１２の直鎖状アルキル基、分岐状アルキル基、環状アルキル基を示す。）
以下、本発明について詳細に説明する。

(1)
(Here, R ₁ and R ₂ each independently represent a linear alkyl group having 1 to 12 carbon atoms, a branched alkyl group, or a cyclic alkyl group.)
Hereinafter, the present invention will be described in detail.

  The polarizer protective film of the present invention is a polarizer protective film made of a specific fumaric acid diester resin.

The fumaric acid diester resin used in the present invention comprises 50 mol% or more of a fumaric acid diester residue unit represented by the general formula (1), and is a number average molecular weight in terms of standard polystyrene determined by gel permeation chromatography. Is 10,000 or more. Here, R ₁ and R ₂ in the fumaric acid diester residue unit represented by the general formula (1) are each independently a linear alkyl group having 1 to 12 carbon atoms, a branched alkyl group, or a cyclic alkyl group. Group, which may be substituted with a halogen such as fluorine or chlorine, an ether group, an ester group or an amino group. Examples of the linear alkyl group having 1 to 12 carbon atoms include a methyl group, an ethyl group, and a propyl group. , A butyl group, a hexyl group and the like. Examples of the branched alkyl group having 1 to 12 carbon atoms include isopropyl group, s-butyl group, t-butyl group, s-pentyl group, t-pentyl group, s- A hexyl group, a t-hexyl group, etc. are mentioned, As a C1-C12 cyclic alkyl group, a cyclopropyl group, a cyclopentyl group, a cyclohexyl group etc. are mentioned, for example, Among these, resistance is good. Sex, isopropyl group since the polarizer protective film having excellent mechanical properties, s- butyl, t- butyl group, a cyclopentyl group, a cyclohexyl group are preferred, an isopropyl group is preferable. Here, when R ₁ and R ₂ are a linear alkyl group, branched alkyl group or cyclic alkyl group having a carbon number greater than 12, the heat resistance and mechanical properties of the polarizer protective film are lowered. Specific examples of the fumarate diester residue unit represented by the general formula (1) include, for example, dimethyl fumarate residue, diethyl fumarate residue, dipropyl fumarate residue, dibutyl fumarate residue, dihexyl fumarate. Residue, diisopropyl fumarate residue, di-s-butyl fumarate residue, di-t-butyl fumarate residue, di-s-pentyl fumarate residue, di-t-pentyl fumarate residue, fumarate Examples include acid di-s-hexyl residue, di-t-hexyl fumarate residue, dicyclopropyl fumarate residue, dicyclopentyl fumarate residue, dicyclohexyl fumarate residue, among which diisopropyl fumarate residue Group, di-s-butyl fumarate residue, di-t-butyl fumarate residue, dicyclopentyl fumarate residue, dicyclohexyl fumarate residue and the like are preferable. Mar diisopropyl residues are preferred.

  Further, the fumaric acid diester resin is composed of 50 mol% or more of a fumaric acid diester residue unit represented by the general formula (1), and is substantially a fumaric acid diester residue represented by the general formula (1). It consists of 50 mol% or more of units and 50 mol% or less of residue units composed of other monomers, and among them, the fumaric acid diester residue unit is 70 mol because of being a polarizer protective film with excellent heat resistance and mechanical properties. % Or more, preferably 80 mol% or more. When the fumaric acid diester residue unit is less than 50 mol%, the polarizer protective film has low heat resistance and optical properties. Residue units composed of the other monomers include, for example, styrene residues such as styrene residues and α-methylstyrene residues; acrylic acid residues; methyl acrylate residues, ethyl acrylate residues, acrylic Acrylic acid ester residues such as butyl acid residues; methacrylic acid residues; methyl methacrylate residues such as methyl methacrylate residues, ethyl methacrylate residues and butyl methacrylate residues; vinyl acetate residues and propion One type or two or more types of vinyl ester residues such as vinyl acid residues; acrylonitrile residues; methacrylonitrile residues; olefin residues such as ethylene residues and propylene residues;

  Further, the fumaric acid diester resin has a number average molecular weight (Mn) in terms of standard polystyrene determined by gel permeation chromatography (hereinafter referred to as GPC) of 10,000 or more. The film is preferably 20000 or more and 200000 or less because the film is excellent in mechanical properties, heat resistance and molding processability. When Mn is less than 10,000, the optical properties of the polarizer protective film become poor.

  As a method for producing the fumaric acid diester resin used in the present invention, it may be produced by any method as long as the fumaric acid diester resin is obtained. For example, a method of radical polymerization of monomers of fumaric acid diesters, Or it can manufacture by the method of radical copolymerizing the monomer copolymerizable with fumaric acid diesters. Examples of the fumaric acid diesters include dimethyl fumarate, diethyl fumarate, dipropyl fumarate, dibutyl fumarate, dihexyl fumarate, diisopropyl fumarate, di-s-butyl fumarate, and di-t-butyl fumarate. , Di-s-pentyl fumarate, di-t-pentyl fumarate, di-s-hexyl fumarate, di-t-hexyl fumarate, dicyclopropyl fumarate, dicyclopentyl fumarate, dicyclohexyl fumarate, etc. Examples of monomers copolymerizable with fumaric acid diesters include styrenes such as styrene and α-methylstyrene; acrylic acid; acrylic acid esters such as methyl acrylate, ethyl acrylate, and butyl acrylate; Methacrylic acid; methyl methacrylate, ethyl methacrylate, butyl methacrylate Methacrylic acid esters; vinyl acetate, vinyl esters such as vinyl propionate and the like; acrylonitrile; methacrylonitrile; ethylene, olefins such as propylene, may be mentioned one or two or more such.

  When performing radical polymerization or radical copolymerization, it can be performed by a known polymerization method. For example, any of bulk polymerization method, solution polymerization method, suspension polymerization method, precipitation polymerization method, emulsion polymerization method and the like is adopted. Is possible.

  Examples of the polymerization initiator used in radical polymerization or radical copolymerization include benzoyl peroxide, lauryl peroxide, octanoyl peroxide, acetyl peroxide, di-t-butyl peroxide, t-butylcumyl peroxide, dichloride. Organic peroxides such as milperoxide, t-butylperoxyacetate, t-butylperoxybenzoate, perbutylpivalate; 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′- Azo series such as azobis (2-butyronitrile), 2,2′-azobisisobutyronitrile, dimethyl-2,2′-azobisisobutyrate, 1,1′-azobis (cyclohexane-1-carbonitrile) Initiators are mentioned.

  The solvent that can be used when performing radical polymerization or radical copolymerization is not particularly limited, for example, aromatic solvents such as benzene, toluene, xylene; alcohol solvents such as methanol, ethanol, propyl alcohol, butyl alcohol; Examples include cyclohexane, dioxane, tetrahydrofuran, acetone, methyl ethyl ketone, dimethylformamide, isopropyl acetate, and a mixed solvent thereof.

  The polymerization temperature at the time of performing radical polymerization or radical copolymerization can be appropriately set according to the decomposition temperature of the polymerization initiator, and is generally preferably in the range of 40 to 150 ° C.

  And it becomes the polarizer protective film of this invention by using these fumaric acid diester type-resins as a polarizer protective film.

  The thickness of the polarizer protective film is 10 to 250 μm, more preferably 30 to 100 μm. Here, when the thickness of the film is less than 10 μm, the mechanical properties and supportability of the polarizer protective film are lowered. On the other hand, when the thickness of the film exceeds 250 μm, the moisture permeability of the polarizer protective film is deteriorated, which is not preferable.

The saturated water absorption at 23 ° C. of the polarizer protective film is 4% or less, preferably 2% or less, and particularly preferably 1.5% or less. When the saturated water absorption is larger than 4%, the dimensional stability of the polarizer protective film is deteriorated, which is not preferable. Further, the moisture permeability of the polarizer protective film measured at 40 ° C. and 90% Rh is 70 g / m ² · 24 h or more, preferably 100 g / m ² · 24 h or more, particularly preferably 200 g / m ² · 24 h or more, more preferably Is 300 g / m ² · 24 h or more. When the moisture permeability is less than 70 g / m ² · 24 h, when the polarizer such as PVA is bonded to the polarizer protective film, moisture loss in the PVA is deteriorated, resulting in poor bonding such as swelling and bubbles. Therefore, it is not preferable.

  Moreover, as for a polarizer protective film, the haze measured based on JISK7105 (1981 version) has preferable 2.0 or less, Most preferably, it is 1.0 or less.

  Further, the in-plane retardation of the polarizer protective film is preferably 10 nm or less, particularly preferably 5 nm or less, in order to obtain good display characteristics.

  As a method for producing a polarizer protective film comprising the fumaric acid diester-based resin of the present invention, any method may be used as long as the polarizer protective film can be produced. For example, melt extrusion, solution casting, press molding, etc. It can be molded by a general molding method, and among them, a polarizer protective film having excellent optical properties, heat resistance, surface properties and the like can be obtained.

  Here, the solution casting method is a method in which a resin solution (hereinafter referred to as a dope) is generally cast on a support substrate and then heated to evaporate the solvent to obtain a film. As a casting method, for example, a T-die method, a doctor blade method, a bar coater method, a roll coater method, a lip coater method or the like is used. Among them, a dope is applied from the T die at a temperature of 10 to 50 ° C. by the T die method. A method of continuously extruding to a belt-shaped or drum-shaped support substrate is preferably used. Examples of the support substrate used include a glass substrate; a metal substrate such as stainless steel or a ferrotype; and a plastic substrate such as polyethylene terephthalate. In addition, in order to industrially continuously form a polarizer protective film having high surface properties and optical homogeneity, a metal substrate having a mirror-finished surface is preferably used.

  As the solvent used in the solution casting method, any solvent can be used as long as the fumaric acid diester resin is soluble, such as chloroform, tetrahydrofuran, methylene chloride, acetone, methyl ethyl ketone, ethyl acetate, butyl acetate and the like. Can be used. In this case, the viscosity of the fumaric acid diester resin solution is preferably 100 to 50000 cps, particularly preferably 500 to 30000 cps, more preferably 1000 to 10000 cps since a polarizer protective film having excellent surface smoothness and thickness accuracy can be obtained. It is. And it becomes what becomes the polarizer protective film of this invention by heat-evaporating this solvent, and the temperature at the time of heat-evaporating has preferable 30-200 degreeC.

  The polarizer protective film made of the 'fumaric acid diester resin of the present invention can be uniaxially or biaxially stretched. Examples of the uniaxial stretching method in this case include a method of stretching by a tenter, a method of rolling by a calender, a method of stretching between rolls, a free width uniaxial stretching method, a constant width uniaxial stretching method, and the like. Examples of the biaxial stretching method include a method of stretching with a tenter, a sequential biaxial stretching method, and a simultaneous biaxial stretching method. Moreover, when performing a extending | stretching process, it is preferable to perform an extending | stretching process within the temperature range of glass transition temperature-20 degreeC-glass transition temperature +30 degreeC of a fumaric acid diester type resin.

  Since the polarizer protective film of the present invention is a polarizer protective film having thermal stability, it is preferably a polarizer protective film obtained by adding an antioxidant to a fumaric acid diester resin. Examples of the agent include hindered phenol antioxidants, phosphorus antioxidants, sulfur antioxidants, lactone antioxidants, amine antioxidants, hydroxylamine antioxidants, vitamin E antioxidants. In addition, other antioxidants may be mentioned, and these antioxidants may be used alone or in combination. The added amount of the antioxidant is 0.01 to 10 parts by weight with respect to 100 parts by weight of the fumaric acid diester resin because it becomes a polarizer protective film excellent in thermal stability and heat-resistant coloring when exposed to high temperatures. Is preferable, and 0.5 to 3.0 parts by weight is particularly preferable.

  Among these antioxidants, it is preferable to use a hindered phenol-based antioxidant and a phosphorus-based antioxidant because a polarizer protective film having particularly excellent thermal stability can be obtained. As addition amount of phosphorus antioxidant, it is preferable to add 0-1000 weight part of phosphorus antioxidant with respect to 100 weight part of hindered phenolic antioxidant, and adding 100-500 weight part especially. Is preferred.

  Examples of the hindered phenol-based antioxidant include pentaerythritol-tetrakis (3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate), thiodiethylene-bis (3- (3,5-dioxy). -T-butyl-4-hydroxyphenyl) propionate), octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, N, N'-hexane-1,6-diylbis (3- (3,5-di-t-butyl-4-hydroxyphenyl) propionamide), diethyl ((3,5-bis (1,1-dimethylethyl) -4-hydroxyphenyl) methyl) phosphate, 3,3 ′, 3 ″, 5,5 ′, 5 ″ -hexa-t-butyl-a, a ′, a ″-(mesitylene-2,4,6-triyl) tri-p-cle , Ethylenebis (oxyethylene) bis (3- (5-t-butyl-4-hydroxy-m-tolyl) propionate), hexamethylene-bis (3- (3,5-di-t-butyl-4) -Hydroxyphenyl) propionate), 1,3,5-tris (3,5-di-t-butyl-4-hydroxybenzyl) -1,3,5-triazine-2,4,6 (1H, 3H, 5H ) -Trione, 1,3,5-tris ((4-tert-butyl-3-hydroxy-2,6-xylyl) methyl) -1,3,5-triazine-2,4,6 (1H, 3H, 5H) -trione, 2,6-di-t-butyl-4- (4,6-bis (octylthio) -1,3,5-triazin-2-ylamino) phenol, 3,9-bis (2- ( 3- (3-t-butyl-4-hydroxy-5-methyl Ruphenyl) propionyloxy) -1,1-dimethylethyl) -2,4,8,10-tetraoxaspiro (5,5) undecane and the like, among which pentaerythritol-tetrakis (3- (3,5- Di-t-butyl-4-hydroxyphenyl) propionate) is preferred.

  Examples of phosphorus antioxidants include tris (2,4-di-t-butylphenyl) phosphite, bis (2,4-bis (1,1-dimethylethyl) -6-methylphenyl) ethyl ester phosphorous Acid, tetrakis (2,4-di-t-butylphenyl) (1,1-biphenyl) -4,4′-diylbisphosphonite, bis (2,4-di-t-butylphenyl) pentaerythritol diphos Phyto, bis (2,6-di-t-butyl-4-methylphenyl) pentaerythritol diphosphite, bis (2,4-dicumylphenyl) pentaerythritol-diphosphite, tetrakis (2,4-t-butylphenyl) ) (1,1-biphenyl) -4,4′-diylbisphosphonite, di-t-butyl-m-cresyl-phosphonite, etc. But tris (2,4-di -t- butyl-phenyl) phosphite is preferred.

  Examples of the sulfur-based antioxidant include didodecyl-3,3'-thiodipropionate and dioctadecyl-3,3'-thiodipropionate.

  Examples of the lactone antioxidant include a reaction product of 3-hydroxy-5,7-di-t-butyl-furan-2-one and o-xylene.

  The polarizer protective film of the present invention is preferably a polarizer protective film obtained by further adding a UV absorber to a fumaric acid diester resin for the purpose of preventing deterioration of the liquid crystal compound. Examples thereof include UV absorbers such as benzotriazole UV absorbers, benzophenone UV absorbers, triazine UV absorbers, and benzoate UV absorbers.

  Examples of the triazole ultraviolet absorber include 2- (2H-benzotriazol-2-yl) -p-cresol, 2- (2H-benzotriazol-2-yl) -4-6-bis (1-methyl-1) -Phenylethyl) phenol, 2- [5-chloro (2H) -benzotriazol-2-yl] -4-methyl-6- (t-butyl) phenol, 2,4-di-t-butyl-6- (5 -Chlorobenzotriazol-2-yl) phenol, 2- (2H-benzotriazol-2-yl) -4,6-di-t-pentylphenol, 2- (2H-benzotriazol-2-yl) -4- (1,1,3,3-tetramethylbutyl) phenol, 2,2′-methylenebis [6- (2H-benzotriazol-2-yl) -4- (1,1,3,3-tetramethyl) Chill) phenol] compound of one or more selected from the like.

  Examples of benzophenone ultraviolet absorbers include 2,4-di-hydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid, 2-hydroxy-4-n-octate. One kind selected from xylbenzophenone, 2,2-di-hydroxy-4-methoxybenzophenone, 2,2,4,4-tetrahydroxybenzophenone, 2,2-di-hydroxy-4,4-dimethoxybenzophenone, etc. The above compounds are mentioned.

  Examples of the triazine-based ultraviolet absorber include 2- (4,6-di-phenyl-1,3,5-triazin-2-yl) -5-[(hexyl) oxy] -phenol.

  Examples of the benzoate ultraviolet absorber include 2,4-di-t-butylphenyl-3,5-di-t-butyl-4-hydroxybenzoate, 2,4-di-t-pentylphenyl-3,5- Examples include di-t-butyl-4-hydroxybenzoate. One or more of these ultraviolet absorbers can be used in combination.

  These ultraviolet absorbers can be added to the hard coat agent in addition to the resin film.

  Moreover, the polarizer protective film of the present invention may be a polarizer protective film obtained by adding a hindered amine light stabilizer to a fumaric acid diester resin, and the hindered amine light stabilizer has an effect of suppressing thermal coloring. A hindered amine light stabilizer having a molecular weight of 1000 or more is preferable, and a hindered amine light stabilizer having a molecular weight of 1500 or more is particularly preferable because it is an excellent polarizer protective film. Further, the amount of hindered amine light stabilizer added is 0.01 to 1.5 with respect to 100 parts by weight of the fumaric acid diester resin because it becomes a polarizer protective film with excellent thermal coloring prevention effect and light stabilization effect. It is preferably part by weight, particularly preferably 0.05 to 1 part by weight, and more preferably 0.1 to 0.5 part by weight. Examples of such a hindered amine light stabilizer include poly ((6-morpholino-s-triazine-2,4-diyl) ((2,2,6,6-tetramethyl-4-piperidyl) imino) hexamethylene. ((2,2,6,6-tetramethyl-4-piperidyl) imino)), poly ((6- (1,1,3,3-tetramethylbutyl) amino-1,3,5-triazine-2 , 4-diyl) ((2,2,6,6-tetramethyl-4-piperidyl) imino) hexamethylene ((2,2,6,6-tetramethyl-4-piperidyl) imino), dibutylamine-1 , 3,5-triazine-N, N′-bis (2,2,6,6-tetramethyl-4-piperidyl) -1,6-hexamethylenediamine and N- (2,2,6,6-tetra Methyl-4-piperidyl) buty Amine polycondensate, N, N′-bis (3-aminopropyl) ethylenediamine-2,4-bis (N-butyl-N- (1,2,2,6,6-pentamethyl-4-piperidyl) amino ) -6-chloro-1,3,5-triazine condensate, dimethyl succinate-1- (2-hydroxyethyl) -4-hydroxy-2,2,6,6-tetramethylpiperidine condensate, etc. These can be used in one or more kinds.

  Furthermore, the polarizer protective film of the present invention is within the range not impairing the physical properties of the present invention, and other polymers, surfactants, polymer electrolytes, conductive complexes, inorganic fillers, pigments, dyes, antistatic agents, antiblocking agents. A lubricant or the like can be added.

  By sticking these polarizer protective films to at least one surface of the polarizer, the polarizing plate of the present invention is obtained. As a method of pasting at that time, for example, a known pressure-sensitive adhesive, adhesive, or the like can be used. Examples of the adhesive include polyurethane-based adhesives, polyester-based adhesives, polyacrylic adhesives, and the like. Examples of the pressure-sensitive adhesive include polyester-based adhesives, acrylic-based adhesives, silicon-based adhesives, and rubber-based adhesives. Agents and the like. Moreover, as a process before bonding, it is preferable to perform a surface modification process in order to obtain high adhesiveness.

  The polarizer used in the polarizing plate of the present invention may be any polarizer as long as it has a function of transmitting only light having a specific vibration direction. For example, a polyvinyl alcohol film or the like is stretched, and iodine or two-color Polyvinyl alcohol polarizers dyed with reactive dyes; polyene polarizers such as dehydrated polyvinyl alcohol and dehydrochlorinated polyvinyl chloride; reflective polarizers using cholesteric liquid crystals; thin film crystal film polarizers Among them, polyvinyl alcohol polarizers are preferably used. Examples of the polyvinyl alcohol polarizer include hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, ethylene / vinyl acetate copolymer partially saponified films, iodine and dichroic dyes, etc. A dichroic substance is adsorbed and uniaxially stretched. Among these, a polarizer composed of a polyvinyl alcohol film and a dichroic substance such as iodine is preferably used. The thickness of these polarizers is not particularly limited, and is generally about 1 to 100 μm.

  Further, the polarizing plate of the present invention in which the polarizer protective film is bonded to at least one surface of the polarizer, the fumaric acid diester resin or other resin used in the present invention is provided on the other surface of the polarizer as necessary. It is also possible to laminate a film made of Examples of films made of other resins include triacetyl cellulose film, polyether sulfone film, polyarylate film, polyethylene terephthalate film, polynaphthalene terephthalate film, polycarbonate film, cyclic polyolefin film, maleimide resin film, fluorine resin film, etc. Is mentioned. The film made of these other resins may be a retardation film having a specific retardation.

  The polarizing plate of the present invention is preferably a laminate having at least one hard coat layer in order to improve surface properties and scratch resistance. Examples of the hard coat layer include a hard coat layer made of, for example, a silicon resin, an acrylic resin, an acrylic silicon resin, an ultraviolet curable resin, a urethane hard coat agent, etc. Among them, transparency, scratch resistance, From the viewpoint of chemical resistance, a hard coat layer made of an ultraviolet curable resin is preferable. One or more of these hard coat layers can be used. Examples of the ultraviolet curable resin include one or more ultraviolet curable resins selected from ultraviolet curable acrylic urethane, ultraviolet curable epoxy acrylate, ultraviolet curable (poly) ester acrylate, ultraviolet curable oxetane, and the like. As for the thickness of a hard-coat layer, 0.1-100 micrometers is preferable, Especially preferably, it is 1-50 micrometers, More preferably, it is 2-20 micrometers. Further, a primer treatment can be performed between the hard coat layers.

  The polarizing plate of the present invention can be subjected to a known antiglare treatment such as antireflection or low reflection treatment.

  The polarizer protective film and polarizing plate of the present invention can be suitably used for liquid crystal televisions, liquid crystal monitors, notebook computers, mobile phones and the like.

  The polarizer protective film of the present invention is excellent in optical properties such as little coloring, high light transmittance, small haze, small photoelastic constant, small in-plane retardation, and good heat resistance. Furthermore, it has the characteristics of having a low water absorption rate and excellent moisture permeability, and is useful as a polarizer protective film. Furthermore, this polarizer protective film can be used suitably for a polarizing plate.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples. The analysis / evaluation methods used in the examples are shown below. The reagents and films used were commercially available unless otherwise noted.

~ Measurement of number average molecular weight ~
It measured as a standard polystyrene conversion value using the gel permeation chromatography (GPC) (the Tosoh Co., Ltd. make, HLC-802A).

~ Measurement of yellowness ~
It measured based on JISK7105 using the color computer (the Suga Test Instruments make, MOEDL S-6). (Reflection method, tristimulus value of reflector: X = 79.57, Y = 81.79, Z = 94.47).

~ Measurement of haze and light transmittance ~
Measured according to JIS K7105 (1981 edition).

~ Measurement of photoelastic coefficient ~
The photoelastic constant was measured at a tensile rate of 1% / s using an optical rheometer (manufactured by Oak Seisakusho, HRS-100).

~ Measurement of in-plane retardation ~
In-plane retardation using a polarizing microscope (Senarmont interferometry) using a Senarmont compensator described in Introduction to Polarized Light Microscopes of Polymer Materials (Hiroshi Hiroya, Agne Technology Center Edition, Chapter 5, p. 78-82 (2001)) Was measured.

~ Measurement of heat resistance ~
For heat resistance, the obtained film was allowed to stand for 1 hour in an oven set at a predetermined temperature, and the highest temperature at which no deformation or coloring was observed was defined as heat resistance.
~ Measurement of saturated water absorption ~
The saturated water absorption was determined by measuring the amount of water absorbed when the obtained film was immersed in water at 23 ° C.
~ Measurement of moisture permeability ~
The moisture permeability was measured according to JIS Z0208 (conditions: 40 ° C. 90% Rh).

Synthesis Example 1 (Production of diisopropyl fumarate homopolymer)
A 3-liter autoclave was charged with 3.68 g of partially saponified polyvinyl alcohol, 1800 g of distilled water, 300 g of diisopropyl fumarate, and 0.35 g of perbutyl pivalate as a polymerization initiator, conditions of a polymerization temperature of 55 ° C. and a polymerization time of 50 hours. Suspension radical polymerization reaction was carried out. The obtained particles were filtered, washed thoroughly with methanol, and dried at 80 ° C. overnight to obtain a diisopropyl fumarate homopolymer. The number average molecular weight of the obtained diisopropyl fumarate homopolymer was 60,000.

Synthesis Example 2 (Production of diisopropyl fumarate copolymer)
In a 3 liter autoclave, 3.68 g of partially saponified polyvinyl alcohol, 1800 g of distilled water, 267 g of diisopropyl fumarate, 13 g of methyl acrylate, and 0.4 g of perbutyl pivalate as a polymerization initiator were charged, polymerization temperature 55 ° C., polymerization Suspension radical polymerization reaction was performed under the conditions of 24 hours. The obtained particles were filtered, washed thoroughly with methanol, and dried overnight at 80 ° C. to obtain a diisopropyl fumarate copolymer. The number average molecular weight of the obtained diisopropyl fumarate copolymer was 65,000. The composition of the obtained copolymer was 82 mol% diisopropyl fumarate residue unit and 18 mol% methyl acrylate residue unit.

Synthesis Example 3 (Production of diisopropyl fumarate copolymer)
In a 3 liter autoclave, 3.68 g of partially saponified polyvinyl alcohol, 1800 g of distilled water, 240 g of diisopropyl fumarate, 35 g of vinyl acetate, and 0.4 g of perbutyl pivalate as a polymerization initiator were charged, polymerization temperature 60 ° C., polymerization time Suspension radical polymerization reaction was performed under conditions of 28 hours. The obtained particles were filtered, washed thoroughly with methanol, and dried overnight at 80 ° C. to obtain a diisopropyl fumarate copolymer. The number average molecular weight of the obtained diisopropyl fumarate copolymer was 87,000. The composition of the obtained copolymer was 74 mol% diisopropyl fumarate residue units and 26 mol% vinyl acetate residue units.

Example 1
The diisopropyl fumarate homopolymer obtained in Synthesis Example 1 is dissolved in chloroform to form a 20% solution (viscosity: 9000 cps), and tris (100% by weight of diisopropyl fumarate homopolymer is used as a phosphorus-based antioxidant. 2,4-di-t-butylphenyl) phosphite 0.35 parts by weight, pentaerythritol-tetrakis (3- (3,5-di-t-butyl-4-hydroxyphenyl) as a hindered phenol antioxidant Propionate) 0.15 parts by weight, 2- (2H-benzotriazol-2-yl) -p-cresol 1 part by weight as an ultraviolet absorber, and then a support substrate of a solution casting apparatus at 30 ° C. by T-die method (Polyethylene terephthalate), dried at 40 ° C., 80 ° C. and 120 ° C. for 1 hour, respectively, and then width 30 mm, to obtain the length 1 m, a film having a thickness of 80 [mu] m.

  Then, the obtained film was cut into a square of 50 mm each, and the light transmittance, haze, yellowness, photoelastic coefficient, in-plane retardation, heat resistance, saturated water absorption rate, and moisture permeability were measured and obtained. The film was suitable for a polarizer protective film. The results are shown in Table 1.

Example 2
A film having a width of 300 mm, a length of 1 m, and a thickness of 40 μm was obtained in the same manner as in Example 1 except that the thickness of the T die was changed. The obtained film was cut into a 50 mm square, and the light transmittance, haze, yellowness, photoelastic coefficient, in-plane retardation, heat resistance, saturated water absorption rate, and moisture permeability were measured. It was suitable for a polarizer protective film. The results are shown in Table 1.

Example 3
The diisopropyl fumarate copolymer obtained in Synthesis Example 2 is dissolved in methylene chloride to form an 18% solution (viscosity: 8000 cps), and tris triphosphoric acid as a phosphorus antioxidant is added to 100 parts by weight of the diisopropyl fumarate copolymer. 0.30 part by weight of (2,4-di-t-butylphenyl) phosphite, pentaerythritol-tetrakis (3- (3,5-di-t-butyl-4-hydroxyphenyl) as a hindered phenol antioxidant ) Propionate) 0.15 parts by weight, 1 part by weight of 2- (2H-benzotriazol-2-yl) -p-cresol was added as a UV absorber. After casting on a support substrate (polyethylene terephthalate) using a bar coater and drying at 40 ° C., 80 ° C. and 120 ° C. for 1 hour, a film having a width of 200 mm, a length of 1 m and a thickness of 90 μm was obtained.

  Then, the obtained film was cut into a square of 50 mm each, and the light transmittance, haze, yellowness, photoelastic coefficient, in-plane retardation, heat resistance, saturated water absorption rate, and moisture permeability were measured and obtained. The film was suitable for a polarizer protective film. The results are shown in Table 1.

Example 4
The diisopropyl fumarate copolymer obtained in Synthesis Example 3 is dissolved in methylene chloride to form an 18% solution (viscosity: 7000 cps). Further, tris as a phosphorus-based antioxidant is added to 100 parts by weight of the diisopropyl fumarate copolymer. 0.30 part by weight of (2,4-di-t-butylphenyl) phosphite, pentaerythritol-tetrakis (3- (3,5-di-t-butyl-4-hydroxyphenyl) as a hindered phenol antioxidant ) Propionate) 0.15 parts by weight, 1 part by weight of 2- (2H-benzotriazol-2-yl) -p-cresol was added as a UV absorber. After casting on a support substrate (polyethylene terephthalate) using a bar coater and drying at 40 ° C., 80 ° C. and 120 ° C. for 1 hour, a film having a width of 200 mm, a length of 1 m and a thickness of 90 μm was obtained.

  Then, the obtained film was cut into a square of 50 mm each, and the light transmittance, haze, yellowness, photoelastic coefficient, in-plane retardation, heat resistance, saturated water absorption rate, and moisture permeability were measured and obtained. The film was suitable for a polarizer protective film. The results are shown in Table 1.

Example 5
The polarizer protective film obtained in Example 1 was bonded to both surfaces of the iodine-dyed PVA stretched film using a polyester-based adhesive (trade name “TM-593” manufactured by Toyo Morton Co., Ltd.). Drying was performed at 60 ° C. and 80 ° C. for 1 hour, respectively. As a result, it was possible to produce a polarizing plate having a good appearance with no defects such as swelling and bubbles.

Comparative Example 1
A polycarbonate resin (manufactured by Aldrich) was obtained in the same manner as in Example 1 to obtain a film having a thickness of 80 μm, light transmittance, haze, yellowness, photoelastic coefficient, in-plane retardation, heat resistance, saturated water absorption, and moisture permeability. Was measured. As a result, the obtained film had a large photoelastic coefficient, a large in-plane retardation, a small moisture permeability, and was not suitable for a polarizer protective film. The results are shown in Table 1.

Comparative Example 2
A cyclic polyolefin resin (polynorbornene having an ester group, manufactured by Aldrich) was obtained in the same manner as in Example 1 to obtain a film having a thickness of 80 μm, light transmittance, haze, yellowness, photoelastic coefficient, in-plane retardation, heat resistance , Saturated water absorption and moisture permeability were measured. As a result, the obtained film had a low moisture permeability and was not suitable for a polarizer protective film. The results are shown in Table 1.

Comparative Example 3
Using a 80 μm thick TAC film (manufactured by Lonza), light transmittance, haze, yellowness, photoelastic coefficient, in-plane retardation, heat resistance, saturated water absorption, and moisture permeability were measured. As a result, the obtained film had a low moisture permeability and was not suitable for a polarizer protective film. The results are shown in Table 1.

Comparative Example 4
A cyclic polyolefin (polynorbornene, manufactured by Nippon Zeon Co., Ltd.) was obtained in the same manner as in Example 1, and a film having a thickness of 80 μm was obtained. Light transmittance, haze, yellowness, photoelastic coefficient, in-plane retardation, heat resistance, saturated water absorption The rate and moisture permeability were measured. As a result, the obtained film had a large saturated water absorption rate, a small moisture permeability, and was not suitable for a polarizer protective film. The results are shown in Table 1.

Comparative Example 5
A polarizing plate was produced using the film of Comparative Example 4 in the same manner as in Example 5. However, it was not possible to obtain a polarizing plate having a good appearance due to poor moisture loss and foaming and swelling.

Claims (7)

It consists of a fumaric acid diester resin having a number average molecular weight of 10,000 or more in terms of standard polystyrene determined by gel permeation chromatography, consisting of 50 mol% or more of the fumaric acid diester residue unit represented by the general formula (1). A polarizer protective film having a thickness of 10 to 250 μm, a saturated water absorption at 23 ° C. of 4% or less, and a moisture permeability measured at 40 ° C. and 90% Rh of 70 g / m ² · 24 h or more.

(1)
(Here, R ₁ and R ₂ each independently represent a linear alkyl group having 1 to 12 carbon atoms, a branched alkyl group, or a cyclic alkyl group.) 0.01 to 10 parts by weight of an antioxidant comprising hindered phenol antioxidant / phosphorus antioxidant = 100/0 to 100/1000 (weight ratio) with respect to 100 parts by weight of the fumaric acid diester resin The polarizer protective film according to claim 1, wherein the polarizer protective film is added. 3. The polarizer protection according to claim 2, wherein the hindered phenol-based antioxidant is pentaerythritol-tetrakis (3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate). the film. The polarizer protective film according to claim 2, wherein the phosphorus-based antioxidant is tris (2,4-di-t-butylphenyl) phosphite. The polarizer protective film obtained by further adding 0.01 to 2 parts by weight of an ultraviolet absorber to 100 parts by weight of the fumaric acid diester resin, according to any one of claims 2 to 4. Polarizer protective film. A polarizer comprising the polarizer protective film according to claim 1 bonded to at least one surface of the polarizer. The polarizing plate according to claim 6, wherein the polarizer is a polyvinyl alcohol-based polarizer.