JP2017102368A - Polarizing plate protective film and polarizing plate comprising the same - Google Patents

Abstract

[Problem] To provide a polarizer protective film for IPS applications that is improved in process warpage and thermal warpage and has excellent flatness, surface quality, and viewing angle characteristics, and a polarizer equipped with the same. [Solution] The polarizer protective film contains a norbornene resin having a norbornane skeleton represented by general formula (1) and a matting agent, and has a retardation value Ro defined by formula (i) of 0 to 10 nm, a retardation value Rt defined by formula (ii) of -10 to 10 nm, and a film thickness of 5.0 to 15.0 μm. Formula (i) Ro = (nx - ny) × d, Formula (ii) Rt = {(nx + ny)/2 - nz} × d [Selected Figure] None

Description

  The present invention relates to a polarizing plate protective film and a polarizing plate provided with the same. More specifically, the present invention provides a polarizing plate protective film for use in an IPS (In-Place-Switching) type liquid crystal display device, which improves process warpage and thermal warpage, and is excellent in flatness, surface quality, and viewing angle characteristics. The present invention relates to a polarizing plate provided.

  A polarizing plate provided in a liquid crystal display device, an organic electroluminescence display device, or the like is generally composed of a polarizer and a pair of polarizing plate protective films that sandwich the polarizer.

  Conventionally, a triacetyl cellulose (hereinafter abbreviated as TAC) film has been widely used as a polarizing plate protective film for liquid crystal display devices, but has a drawback of having hygroscopicity and moisture permeability. In particular, when a TAC film having a film thickness of 15.0 μm or less is bonded as a polarizing plate protective film to a liquid crystal cell in which thinning is required, the polarizing plate is caused by the moisture permeability of the TAC film. In particular, a polarizer made of polyvinyl alcohol (PVA) undergoes hygroscopic expansion and the elongation rate of the polarizing plate is larger than the elongation rate of the liquid crystal cell. As a result, the liquid crystal cell is warped. A problem (hereinafter referred to as “process warp”) occurs.

  In addition, when a TAC film is used as a polarizing plate protective film of a polarizing plate, after the polarizing plate is bonded to a liquid crystal cell, for example, when it is treated in a high temperature environment of 85 ° C. for 500 hours, the thermal contraction of polyvinyl alcohol The problem of warping the liquid crystal cell (hereinafter referred to as “thermal warping”) occurs.

  As a method for solving the above-mentioned problems, a study of using a norbornene-based film having excellent properties such as water resistance, heat resistance, transparency and dimensional stability as a polarizing plate protective film has been actively conducted. .

  However, when a norbornene-based film is used as a polarizing plate protective film, there has been a problem in flatness and surface quality, although further thinning is required with the recent reduction in weight of display devices and the expansion of the mobile market. It was. For example, a conventionally used norbornene-based film has a release film bonded from the viewpoint of preventing scratches on the surface, and after the polarizing plate is formed, a heat treatment is performed to improve the flatness. I couldn't do it, so I had a problem with flatness.

  For the above problem, a polarizing plate protective film in which a norbornene-based resin and a norbornene-based resin composition containing silica fine particles are formed by a melt casting method and a knurling is provided at an end of the film is disclosed (for example, a patent Reference 1). According to the method disclosed in Patent Document 1, it has high transparency, and it is said that high handling properties can be obtained by having a knurling portion.

  However, in the method disclosed in Patent Document 1, the film thickness described in Examples and the like is in the range of 28 to 40 μm. With such a thick film configuration, when a polarizing plate is configured, a norbornene-based film is used. Since the elongation rate of the resin is higher than the shrinkage rate of the polyvinyl alcohol which is a polarizer, there is a problem that the thermal warpage increases.

JP 2011-128356 A

  The present invention has been made in view of the above problems and situations, and its solution is to improve process warpage and thermal warpage, and to provide polarization for IPS liquid crystal display devices that are excellent in flatness, surface quality, and viewing angle characteristics. It is providing a board protective film and a polarizing plate provided with the same.

  In order to solve the above problems, the present inventor, in the process of studying the cause of the above problems, etc., a norbornene-based resin having a norbornane skeleton having a specific structure, a matting agent, and a thin film having a specific retardation value The present inventors have found that a polarizing plate protective film can suppress a process warp and a thermal warp and can provide a polarizing plate protective film excellent in flatness, surface quality, and viewing angle characteristics.

  That is, the said subject which concerns on this invention is solved by the following means.

1. Containing a norbornene-based resin having a norbornane skeleton represented by the following general formula (1), and a matting agent;
The retardation value Ro defined by the following formula (i) is within the range of 0 to 10 nm, the retardation value Rt defined by the following formula (ii) is within the range of −10 to 10 nm,
And the film thickness exists in the range of 5.0-15.0 micrometers, The polarizing plate protective film characterized by the above-mentioned.

〔式中、Ｒは、炭素数が１〜３の直鎖又は分岐アルキル基を表す。〕
式（ｉ）
Ｒｏ＝（ｎ_ｘ−ｎ_ｙ）×ｄ
式（ii）
Ｒｔ＝｛（ｎ_ｘ＋ｎ_ｙ）／２−ｎ_ｚ｝×ｄ
〔式中、Ｒｏはフィルムの面内方向のリターデーション値、Ｒｔはフィルムの厚さ方向のリターデーション値、ｎ_ｘはフィルム面内の遅相軸方向の屈折率、ｎ_ｙはフィルム面内の進相軸方向の屈折率、ｎ_ｚはフィルムの厚さ方向の屈折率（屈折率は２３℃、５５％ＲＨの環境下、波長５９０ｎｍで測定）、ｄはフィルムの厚さ（ｎｍ）を表す。〕
２．前記マット剤の含有量が、フィルム全質量の０．１〜０．５質量％の範囲内であることを特徴とする第１項に記載の偏光板保護フィルム。

[In formula, R represents a C1-C3 linear or branched alkyl group. ]
Formula (i)
_{Ro = (n x -n y)} × d
Formula (ii)
Rt = {(n _x + n _y ) / 2−n _z } × d
Wherein, Ro-plane direction of the retardation value of the film, Rt is the thickness direction of the retardation value of the film, n _x is a refractive index in a slow axis direction in the film plane, n _y is in the film plane The refractive index in the fast axis direction, _nz is the refractive index in the thickness direction of the film (the refractive index is measured at a wavelength of 590 nm in an environment of 23 ° C. and 55% RH), and d is the thickness (nm) of the film. . ]
2. 2. The polarizing plate protective film according to item 1, wherein the content of the matting agent is in the range of 0.1 to 0.5% by mass of the total mass of the film.

  3. 3. A polarizing plate protective film according to item 1 or 2, wherein a polyester plasticizer is contained.

4). A polarizing plate having a first protective film T1 on the viewing side and a second protective film T2 on the other surface side with a polarizer in between,
At least one of protective film T1 and protective film T2 is a polarizing plate protective film as described in any one of 1st term | claim to 3rd term | claim, The polarizing plate characterized by the above-mentioned.

  5. The polarizing plate according to item 4, wherein the protective film T1 or the protective film T2 contains an ultraviolet absorber.

  6). Both said protective film T1 and protective film T2 are polarizing plate protective films as described in any one of 1st term | claim to 3rd term | claim, and contain the ultraviolet absorber. 5. A polarizing plate according to item 4.

  By the above means of the present invention, it is possible to provide a polarizing plate protective film excellent in flatness, surface quality and viewing angle characteristics, and a polarizing plate using the same and improved in process warpage and thermal warpage.

  The expression mechanism / action mechanism of the effect of the present invention is not clear, but is presumed as follows.

  The present invention contains a norbornene-based resin having a norbornane skeleton represented by the general formula (1) and a matting agent, the retardation value Ro and the retardation value Rt are within a specific range, and the film thickness is 5 By using a polarizing plate protective film in a range of 0.0 to 15.0 μm, process warpage and thermal warpage are suppressed, and planarity, surface quality, and viewing angle characteristics are improved.

  A matting agent is used in combination with a norbornene-based resin having a norbornane skeleton having a low molecular weight alkyl group having 1 to 3 carbon atoms as a substituent within a thickness range of 5.0 to 15.0 μm as defined in the present invention. As a result, the scratch resistance of the film surface is improved, the release film can be freed, and heat correction treatment after film formation can be made possible. As a result, process warpage resistance and heat warpage resistance are improved. In addition, the planarity and surface quality can be improved at the same time. More specifically, the process warpage can be improved by blocking moisture permeation into the polyvinyl alcohol film as a polarizer by using a norbornene resin film having low moisture permeability. Moreover, with respect to thermal warping, the polarizing plate protective film made of a norbornene-based resin having a property of being elongated by heat treatment can counteract the shrinkage of the polyvinyl alcohol film, thereby suppressing warpage due to heat. In addition, by adding a matting agent to the norbornene-based resin, when a film is formed, an appropriate uneven structure can be formed on the surface, thereby improving the scratch resistance of the film surface. As a result, it is assumed that the release film can be made free.

Schematic diagram showing an example of a solution casting film forming apparatus Schematic sectional view showing an example of the configuration of the polarizing plate of the present invention Schematic sectional view showing an example of a liquid crystal display device comprising the polarizing plate of the present invention

  The polarizing plate protective film of the present invention contains a norbornene resin having a norbornane skeleton represented by the general formula (1) and a matting agent, and the retardation value Ro defined by the formula (i) is 0. The retardation value Rt defined by the formula (ii) is in the range of −10 to 10 nm and the film thickness is in the range of 5.0 to 15.0 μm. It is characterized by. This feature is a technical feature common to or corresponding to the claimed invention.

  In the present invention, the content of the matting agent is within the range of 0.1 to 0.5% by mass of the total mass of the film from the viewpoint that the effects intended by the present invention can be further expressed. It is preferable in that an appropriate uneven structure can be formed and an increase in haze or the like can be suppressed.

  Moreover, it is preferable that a polarizing plate protective film contains a polyester plasticizer at the point which can improve a film elastic modulus, slipperiness, and film film surface hardness, and, as a result, can obtain high quality surface quality.

  Moreover, in the polarizing plate of this invention, it is the structure which has 1st protective film T1 in a visual recognition side, and 2nd protective film T2 in the other surface side on both sides of a polarizer, and protective film T1 and protective film T2 It is possible to obtain a polarizing plate excellent in flatness, surface quality, and viewing angle characteristics by constituting at least one of the polarizing plate protective film of the present invention with improved process warpage and thermal warpage.

  Furthermore, the configuration in which the protective film T1 or the protective film T2 contains an ultraviolet absorber is preferable from the viewpoint of further improving the thermal warpage resistance.

  Hereinafter, the present invention, its components, and modes and modes for carrying out the present invention will be described in detail. In addition, in this application, "-" showing a numerical range is used by the meaning containing the numerical value described before and behind that as a lower limit and an upper limit.

<Polarizing plate protective film>
The polarizing plate protective film of the present invention contains a norbornene-based resin having a norbornane skeleton represented by the following general formula (1) and a matting agent, and the retardation value Ro defined by the following formula (i) is 0. The retardation value Rt defined by the following formula (ii) is in the range of −10 to 10 nm and the film thickness is in the range of 5.0 to 15.0 μm. It is characterized by.

  The polarizing plate protective film of the present invention preferably further contains a polyester plasticizer. Moreover, when applying as a protective film of a polarizing plate, it is a preferable form to contain a ultraviolet absorber.

  Hereinafter, details of each component, characteristic value, manufacturing method, and the like of the polarizing plate protective film of the present invention will be described below.

[Norbornene-based resin having a norbornane skeleton represented by the general formula (1)]
The polarizing plate protective film of the present invention contains a norbornene-based resin having a norbornane skeleton represented by the following general formula (1) as a film constituent material.

  In the general formula (1), R represents a linear or branched alkyl group having 1 to 3 carbon atoms. Specific examples represent a methyl group, an ethyl group, an n-propyl group, or an i-propyl group.

The preferred molecular weight of the norbornene-based resin having a norbornane skeleton represented by the general formula (1) according to the present invention is in the range of 0.2 to ⁵ cm ³ / g in intrinsic viscosity [η] inh, more preferably 0.3. It is in the range of ˜3 cm ³ / g, particularly preferably in the range of 0.4 to 1.5 cm ³ / g.

  The number average molecular weight (Mn) is in the range of 8000 to 100,000, more preferably in the range of 10,000 to 80000, and particularly preferably in the range of 12000 to 50000.

  The weight average molecular weight (Mw) is preferably in the range of 100,000 to 180,000, and more preferably in the range of 110000 to 140000.

  When the intrinsic viscosity [η] inh, number average molecular weight (Mn) and weight average molecular weight (Mw) are within the above ranges, the heat resistance and water resistance of the norbornene resin having a norbornane skeleton represented by the general formula (1) , Chemical resistance, mechanical properties, and moldability as a polarizing plate protective film of the present invention are improved.

  Intrinsic viscosity [η] inh is measured using a Ubbelohde viscometer (measuring temperature 30 ° C.) with a resin solution in which a norbornene resin having a norbornane skeleton represented by the general formula (1) is dissolved in chloroform. Can do.

  The number average molecular weight (Mn) and the weight average molecular weight (Mw) are measured using gel permeation chromatography (HLC8220GPC manufactured by Tosoh Corporation) and column (TSK-GEL G6000HXL-G5000HXL-G5000HXL-G4000HXL-G3000HXL in series) manufactured by Tosoh Corporation. . A 20 mg ± 0.5 mg sample is dissolved in 10 ml of tetrahydrofuran and filtered through a 0.45 mm filter. 100 ml of this solution is injected into a column (temperature: 40 ° C.), measured at a detector RI temperature of 40 ° C., and a value converted to styrene is used.

(Matting agent)
One feature of the polarizing plate protective film of the present invention is that it contains a matting agent.

  The matting agent applicable to the polarizing plate protective film of the present invention is usually used as an additive for the film, and in order to improve the poor slipperiness of the film surface, it is possible to give unevenness to the film surface. It is effective and contains organic fine particles or inorganic fine particles to increase film surface roughness, so-called matting, and is used to reduce adhesion and improve scratch resistance. .

  However, the rougher the surface, the higher the haze and the lower the transparency. Therefore, the average particle size and content of the applicable matting agent are limited. The matting agent used in the present invention preferably has an average particle diameter in the range of 1 to 1000 nm, more preferably in the range of 1 to 100 nm, and particularly preferably in the range of 3 to 50 nm.

  The addition amount of the matting agent is preferably in the range of 0.1 to 0.5% by mass, regardless of spherical or irregular fine particles, with respect to 100% by mass of the film.

  In the present invention, the preferred haze value of the polarizing plate protective film containing the matting agent is 2.0% or less, more preferably 1.2% or less, and particularly preferably 0.5% or less.

  The preferable static friction coefficient of the polarizing plate protective film to which the matting agent is added is 1.5 or less, and particularly preferably 1.0 or less. If the static friction coefficient is 1.5 or less, the polarizing plate protective film does not cause creases or wrinkles during winding in film formation and processing, and therefore the winding shape is damaged by creases and wrinkles, or due to creases and wrinkles. There is no problem that the non-uniform tension is not applied to the polarizing plate protective film, and unintentional non-uniform optical characteristics appear on the film surface.

  The matting agent applicable in the present invention is not particularly limited as long as it can be used for a general film, and these matting agents can be used in combination of two or more. Examples of the matting agent according to the present invention include inorganic fine particles and organic fine particles containing a polymer compound.

  Examples of the inorganic fine particles include inorganic fine particles such as barium sulfate, manganese colloid, titanium dioxide, strontium barium sulfate, and silicon dioxide. Further, for example, synthetic silica obtained by a wet method or gelation of silicic acid, etc. And titanium dioxide (rutile type or anatase type) produced by silicon dioxide or titanium slug and sulfuric acid. As the inorganic fine particles, those containing silicon are preferable in that turbidity and haze of the film can be reduced. Many of the fine particles such as silicon dioxide are surface-modified with an organic substance, but such one is preferable because the surface haze of the film can be reduced. Preferred organic materials for surface modification include halosilanes, alkoxysilanes, silazanes, siloxanes, and the like.

  In addition, the polymer compound constituting the organic fine particles includes polytetrafluoroethylene, cellulose acetate, polystyrene, polymethyl methacrylate, polypropyl methacrylate, polymethyl acrylate, polyethylene carbonate, starch, etc., and pulverized classifications thereof. Also mentioned. Alternatively, a high molecular compound synthesized by a suspension polymerization method, a high molecular compound made spherical by a spray drying method or a dispersion method, or an inorganic compound can be used.

  Among the above matting agents, silicon dioxide fine particles (silica fine particles) are preferable.

(Organic solvent used for matting agent dispersion)
The organic solvent used in the preparation of the matting agent dispersion is not particularly limited as long as the matting agent is dispersed and the dispersion can be prepared. The organic solvent used in the present invention is, for example, a solvent selected from a chlorinated solvent such as dichloromethane and chloroform, a chain hydrocarbon having 3 to 12 carbon atoms, a cyclic hydrocarbon, an aromatic hydrocarbon, an ester, a ketone, and an ether. Is preferred. The ester, ketone and ether may have a cyclic structure.

  In the present invention, as the organic solvent used in the method for preparing the matting agent dispersion, one type of organic solvent may be used alone, or two or more types of organic solvents may be mixed and used in an arbitrary ratio.

  When dispersing the matting agent, if the amount of the organic solvent is small, sufficient dispersion cannot be achieved, and agglomerates are generated, causing a foreign matter failure. On the contrary, when the amount of the organic solvent is large, although the dispersibility of the fine particles is excellent, a large amount of the dispersion is prepared, which is not preferable in terms of handling in production. Therefore, the amount of the organic solvent used is preferably in the range of 1000 to 100,000 parts by weight, more preferably in the range of 1500 to 40000 parts by weight, with respect to 100 parts by weight of the matting agent. It is particularly preferable that the amount be in the range of 20000 parts by mass.

[Other additives]
Various additives can be applied to the polarizing plate protective film of the present invention as long as the object effects of the present invention are not impaired.

(Polyester plasticizer)
In the polarizing plate protective film of the present invention, it is possible to obtain a high-quality surface quality by applying a polyester plasticizer to improve the film elastic modulus, slipperiness, and film film surface hardness. preferable.

  The polyester plasticizer is obtained by subjecting a diol and a dicarboxylic acid to a dehydration condensation reaction, and then converting the hydroxyl group (derived from the diol) at the molecular end of the resulting reaction product to a carboxy group of a hydroxy group-containing monocarboxylic acid having a ring structure. And a compound obtained by a dehydration condensation reaction.

  The polyester plasticizer has a structure represented by the following general formula (2).

General formula (2)
B- (GA) _n -GB
In the above general formula (2), B represents a group derived from a hydroxy group-containing monocarboxylic acid having a ring structure. The ring structure refers to a structure having an aliphatic hydrocarbon ring, an aliphatic hetero ring, an aromatic hydrocarbon ring or an aromatic hetero ring, preferably a structure having an aliphatic hydrocarbon ring or an aromatic hydrocarbon ring. . The hydroxy group-containing monocarboxylic acid having a ring structure may be an alicyclic monocarboxylic acid having 5 to 20 carbon atoms, an aromatic monocarboxylic acid having 7 to 20 carbon atoms, and a mixture thereof.

  The alicyclic monocarboxylic acid having 5 to 20 carbon atoms may preferably be an alicyclic monocarboxylic acid having 6 to 15 carbon atoms. Examples of alicyclic monocarboxylic acids include 4-hydroxycyclohexyl acetic acid, 3-hydroxycyclohexyl acetic acid, 2-hydroxycyclohexyl acetic acid, 4-hydroxycyclohexyl propionic acid, 4-hydroxycyclohexyl butyric acid, 4-hydroxycyclohexyl glycolic acid, 4 -Hydroxy-o-methylcyclohexylacetic acid, 4-hydroxy-m-methylcyclohexylacetic acid, 4-hydroxy-p-methylcyclohexylacetic acid, 5-hydroxy-m-methylcyclohexylacetic acid, 6-hydroxy-o-methylcyclohexylacetic acid, 2 , 4-dihydroxycyclohexyl acetic acid, 2,5-dihydroxycyclohexyl acetic acid, 2- (hydroxymethyl) cyclohexyl acetic acid, 3- (hydroxymethyl) cyclohexyl acetic acid, 4- (hydroxymethyl) L) cyclohexylacetic acid, 2- (1-hydroxy-1-methylethyl) cyclohexylacetic acid, 3- (1-hydroxy-1-methylethyl) cyclohexylacetic acid, 4- (1-hydroxy-1-methylethyl) cyclohexylacetic acid, etc. Is included.

  The aromatic monocarboxylic acid having 7 to 20 carbon atoms may preferably be an aromatic monocarboxylic acid having 7 to 15 carbon atoms. Examples of aromatic monocarboxylic acids include 4-hydroxybenzoic acid, 3-hydroxybenzoic acid, 2-hydroxybenzoic acid, 4-hydroxy-o-toluic acid, 3-hydroxy-p-toluic acid, 5-hydroxy- m-toluic acid, 6-hydroxy-o-toluic acid, 2,4-dihydroxybenzoic acid, 2,5-dihydroxybenzoic acid, 2- (hydroxymethyl) benzoic acid, 3- (hydroxymethyl) benzoic acid, 4- (Hydroxymethyl) benzoic acid, 2- (1-hydroxy-1-methylethyl) benzoic acid, 3- (1-hydroxy-1-methylethyl) benzoic acid, 4- (1-hydroxy-1-methylethyl) benzoic acid Acid etc. are included.

  Among these, a hydroxy group-containing monocarboxylic acid containing an aromatic ring (an aromatic monocarboxylic acid containing a hydroxy group) from the viewpoint of imparting sufficient hydrophobicity to the polarizing plate protective film and easily suppressing deterioration of the polarizer due to moisture. ) Is preferred.

  In the formula, G is a group consisting of an alkylene diol having 2 to 12 carbon atoms, a cycloalkylene diol having 6 to 12 carbon atoms, an oxyalkylene diol having 4 to 12 carbon atoms, and an arylene diol having 6 to 12 carbon atoms. A group derived from at least one selected from the above.

  Examples of alkylene diols having 2 to 12 carbon atoms include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1,3-butanediol, 1,2-propane. Diol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl-1,3-propanediol (neopentyl glycol), 2,2-diethyl -1,3-propanediol (3,3-dimethylolpentane), 2-n-butyl-2-ethyl-1,3-propanediol (3,3-dimethylolheptane), 3-methyl-1,5- Pentanediol 1,6-hexanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl-1,3-hexanediol , 2-methyl-1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, include 1,12-octadecanediol like.

  Examples of cycloalkylene diols having 6 to 12 carbon atoms include hydrogenated bisphenol A (2,2-bis (4-hydroxycyclohexyl) propane), hydrogenated bisphenol B (2,2-bis (4-hydroxycyclohexyl) Butane and the like are included.

  Examples of the oxyalkylene diol having 4 to 12 carbon atoms include diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol and the like.

  Examples of the arylene diol having 6 to 12 carbon atoms include bisphenol A and bisphenol B.

  The diol is used as one kind or a mixture of two or more kinds. Among these, alkylene glycols having 2 to 12 carbon atoms are preferable in terms of excellent compatibility with cycloolefin resins.

  In the formula, A is at least one selected from the group consisting of alkylene dicarboxylic acids having 4 to 12 carbon atoms, cycloalkylene dicarboxylic acids having 6 to 12 carbon atoms, and arylenedicarboxylic acids having 8 to 16 carbon atoms. Represents a derived group.

  Examples of the alkylene dicarboxylic acid having 4 to 12 carbon atoms include succinic acid, maleic acid, fumaric acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid and the like.

  Examples of the cycloalkylene dicarboxylic acid having 6 to 16 carbon atoms include 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,5-decahydronaphthalenedicarboxylic acid, 1,4-decahydronaphthalenedicarboxylic acid and the like are included.

  Examples of the arylene dicarboxylic acid having 8 to 16 carbon atoms include phthalic acid, terephthalic acid, isophthalic acid, 1,5-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid and the like.

  The dicarboxylic acid is used as one kind or a mixture of two or more kinds. The dicarboxylic acid is preferably a mixture of alkylene dicarboxylic acid and arylene dicarboxylic acid. The content ratio of the alkylene dicarboxylic acid and the arylenedicarboxylic acid is preferably alkylene dicarboxylic acid: arylene dicarboxylic acid = 40: 60 to 99: 1, and more preferably 50:50 to 90:10.

  In the formula, n represents an integer of 0 or more.

  The number average molecular weight of the polyester plasticizer is preferably 300 to 30000, more preferably 300 to 700, and more preferably 300 to 600. If the number average molecular weight is above a certain level, bleeding out is likely to be suppressed. When the number average molecular weight is not more than a certain value, the compatibility with the cycloolefin-based resin is hardly impaired, and haze increase is easily suppressed.

  The number average molecular weight of the polyester plasticizer can be measured by gel permeation chromatography. Specifically, using a gel permeation chromatography (GPC) measuring device (“HLC-8330” manufactured by Tosoh Corporation), the number average molecular weight (Mn) of the ester compound in terms of standard polystyrene is measured under the following measurement conditions. Can be measured.

(Measurement condition)
Column: “TSK gel SuperHZM-M” × 2 and “TSK gel SuperHZ-2000” × 2 Guard column: “TSK superH-H”
Developing solvent: Tetrahydrofuran Flow rate: 0.35 mL / min The number average molecular weight of the polyester plasticizer can be adjusted by the reaction time of condensation or polycondensation.

  The acid value of the polyester plasticizer is preferably 0.5 mgKOH / g or less, more preferably 0.3 mgKOH / g or less. The hydroxyl value of the polyester plasticizer is preferably 25 mgKOH / g or less, more preferably 15 mgKOH / g or less.

  Polyester plasticizers can be synthesized by a conventional method using a hot melt condensation method by esterification or transesterification of dicarboxylic acid, diol, and end-capping monocarboxylic acid, or dicarboxylic acid and end-capping monocarboxylic acid. It can be performed by any of the interfacial condensation methods of acid chloride and diol. The charging ratio of the diol and the dicarboxylic acid is adjusted so that the molecular terminal is a diol.

  It is preferable that the addition amount with respect to the cycloolefin resin of the polyester plasticizer which has a structure represented by General formula (2) exists in the range of 2-10 mass%. More preferably, it exists in the range of 3-7 mass%. The amount added is 2% by mass or more, and an effect of increasing the hardness of the polarizing plate protective film is recognized, and if it is 10% by mass or less, it is preferable from the viewpoint of improving dimensional stability and haze stability in a high temperature environment.

(UV absorber)
When a polarizing plate having the first protective film T1 on the viewing side and the second protective film T2 on the other surface side with the polarizer in between, at least one of the protective film T1 and the protective film T2 is the present invention. One of the preferred embodiments is that the protective film T1 or the protective film T2 further comprises an ultraviolet absorber.

  As an ultraviolet absorber applied to the polarizing plate protective film of the present invention, from the viewpoint of preventing deterioration of a polarizer and a liquid crystal, it has an excellent ability to absorb ultraviolet rays having a wavelength of 370 nm or less, and from the viewpoint of liquid crystal display property, a wavelength of 400 nm or more. It is preferable to have a characteristic that the absorption of visible light is small.

  Although the ultraviolet absorber applicable to the present invention is not particularly limited, for example, oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, triazine compounds, nickel complex compounds, An inorganic powder etc. are mentioned.

  Examples of the ultraviolet absorber applicable to the present invention include 5-chloro-2- (3,5-di-sec-butyl-2-hydroxylphenyl) -2H-benzotriazole, (2-2H-benzotriazole- 2-yl) -6- (linear and side chain dodecyl) -4-methylphenol, 2-hydroxy-4-benzyloxybenzophenone, 2,4-benzyloxybenzophenone, etc., and tinuvin 109, tinuvin 171, There are tinuvins such as tinuvin 234, tinuvin 326, tinuvin 327, tinuvin 328, and tinuvin 928, all of which are commercially available products from BASF Japan and can be preferably used.

  More preferably used ultraviolet absorbers are benzotriazole ultraviolet absorbers, benzophenone ultraviolet absorbers, and triazine ultraviolet absorbers, and particularly preferably benzotriazole ultraviolet absorbers and benzophenone ultraviolet absorbers.

  For example, as the benzotriazole ultraviolet absorber, a compound represented by the following general formula (b) can be used.

In the general formula (b), R ₁ , R ₂ , R ₃ , R ₄ and R ₅ may be the same or different, and are a hydrogen atom, a halogen atom, a nitro group, a hydroxy group, an alkyl group, an alkenyl group, an aryl group. Represents an alkoxy group, an acyloxy group, an aryloxy group, an alkylthio group, an arylthio group, a mono- or dialkylamino group, an acylamino group or a 5- to 6-membered heterocyclic group, and R ₄ and R ₅ are closed to form a 5- to 6-membered ring The carbocyclic ring may be formed. Moreover, these groups described above may have an arbitrary substituent.

  Although the specific example of a benzotriazole type ultraviolet absorber is given to the following, this invention is not limited to these.

UV-1: 2- (2'-hydroxy-5'-methylphenyl) benzotriazole UV-2: 2- (2'-hydroxy-3 ', 5'-di-tert-butylphenyl) benzotriazole UV-3 : 2- (2'-hydroxy-3'-tert-butyl-5'-methylphenyl) benzotriazole UV-4: 2- (2'-hydroxy-3 ', 5'-di-tert-butylphenyl)- 5-Chlorobenzotriazole UV-5: 2- (2'-hydroxy-3 '-(3 ", 4", 5 ", 6" -tetrahydrophthalimidomethyl) -5'-methylphenyl) benzotriazole UV-6: 2,2-methylenebis (4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol)
UV-7: 2- (2'-hydroxy-3'-tert-butyl-5'-methylphenyl) -5-chlorobenzotriazole UV-8: 2- (2H-benzotriazol-2-yl) -6 (Linear and side chain dodecyl) -4-methylphenol (TINUVIN171)
UV-9: Octyl-3- [3-tert-butyl-4-hydroxy-5- (chloro-2H-benzotriazol-2-yl) phenyl] propionate and 2-ethylhexyl-3- [3-tert-butyl- 4-Hydroxy-5- (5-chloro-2H-benzotriazol-2-yl) phenyl] propionate mixture (TINUVIN 109)
Furthermore, as the benzophenone ultraviolet absorber, a compound represented by the following general formula (c) is preferably used.

In the general formula (c), Y represents a hydrogen atom, a halogen atom, an alkyl group, an alkenyl group, an alkoxy group, or a phenyl group, and these alkyl group, alkenyl group, and phenyl group may have a substituent. Good. A represents a hydrogen atom, an alkyl group, an alkenyl group, a phenyl group, a cycloalkyl group, an alkylcarbonyl group, an alkylsulfonyl group, or a —CO (NH) _n-1- D group, and D represents an alkyl group, an alkenyl group, or a substituent. Represents a phenyl group which may have m and n represent 1 or 2.

  In the above, the alkyl group represents, for example, a linear or branched aliphatic group having up to 24 carbon atoms, the alkoxy group represents, for example, an alkoxy group having up to 18 carbon atoms, and the alkenyl group has, for example, carbon number An alkenyl group up to 16 represents an allyl group, a 2-butenyl group, or the like. In addition, as substituents for alkyl groups, alkenyl groups, and phenyl groups, halogen atoms such as chlorine atoms, bromine atoms, fluorine atoms, etc., hydroxy groups, phenyl groups (this phenyl group is substituted with alkyl groups or halogen atoms, etc.) May be used).

  Specific examples of the benzophenone-based ultraviolet absorber represented by the general formula (c) are shown below, but the present invention is not limited thereto.

UV-10: 2,4-dihydroxybenzophenone UV-11: 2,2'-dihydroxy-4-methoxybenzophenone UV-12: 2-hydroxy-4-methoxy-5-sulfobenzophenone UV-13: Bis (2-methoxy -4-hydroxy-5-benzoylphenylmethane)
In addition, a discotic compound such as a compound having a 1,3,5 triazine ring is also preferably used as the ultraviolet absorber.

  The polarizing plate protective film which concerns on this invention can also contain 2 or more types of ultraviolet absorbers.

  In the present invention, as the ultraviolet absorber, in particular, “2- (2H-benzotriazol-2-yl) -6- (1-methyl-1-phenylethyl) -4- (1,1, “3,3-tetramethylbutyl) phenol” is preferably used because it can provide a thin film while achieving both the UV absorption and low retardation of the second protective film of the present invention.

  The polarizing plate protective film which concerns on this invention can also contain 2 or more types of ultraviolet absorbers.

  As the UV absorber, a polymer UV absorber can be preferably used, and in particular, a polymer type UV absorber described in JP-A-6-148430 is preferably used.

  The method of adding the UV absorber is to add the dope after dissolving the UV absorber in an alcohol such as methanol, ethanol, butanol, a solvent such as methylene chloride, methyl acetate, acetone, dioxolane, or a mixed solvent thereof, or You may add directly in dope composition. For an inorganic powder that does not dissolve in an organic solvent, a dissolver or a sand mill is used in the organic solvent and cellulose ester to disperse and then added to the dope.

  The amount of the UV absorber used is not uniform depending on the type of UV absorber, the operating conditions, etc., but when the dry film thickness of the polarizing plate protective film is 10 to 100 μm, it is 0.5 with respect to the polarizing plate protective film. -10 mass% is preferable, and 0.6-4 mass% is still more preferable.

(Antioxidant)
An antioxidant can be applied to the polarizing plate protective film of the present invention.

  The antioxidant has a role of delaying or preventing the decomposition of the polarizing plate protective film by, for example, the residual solvent halogen in the polarizing plate protective film or phosphoric acid of the phosphoric acid plasticizer. It is preferable to make it contain.

  In this invention, what is generally known can be used as an antioxidant. In particular, lactone, sulfur, phenol, double bond, hindered amine, and phosphorus compounds can be preferably used.

  For example, “Irgafos XP40, Irgafos XP60” commercially available from BASF Japan Ltd. can be mentioned.

  Examples of the sulfur compound include “Sumilizer TPL-R” and “Sumilizer TP-D” commercially available from Sumitomo Chemical Co., Ltd.

  The phenolic compound preferably has a 2,6-dialkylphenol structure. For example, “Irganox 1076”, “Irganox 1010” commercially available from BASF Japan Ltd., and ADEKA Corporation are commercially available. "Adeka Stub AO-50" can be mentioned.

  The above double bond compounds are commercially available from Sumitomo Chemical Co., Ltd. under the trade names “Sumilizer GM” and “Sumilizer GS”.

  Examples of the hindered amine compound include “Tinvin 144” and “Tinvin 770” commercially available from BASF Japan, and “ADK STAB LA-52” commercially available from ADEKA.

  Examples of the phosphorus compound include “Sumizer GP” commercially available from Sumitomo Chemical Co., Ltd., “ADK STAB PEP-24G”, “ADK STAB PEP-36” and “ADK STAB 3010” commercially available from ADEKA Corporation. "IRGAFOS P-EPQ" commercially available from BASF Japan, and "GSY-P101" commercially available from Sakai Chemical Industry.

(Peeling aid)
Since the polarizing plate protective film of the present invention has high adhesion to the metal support, it is easy to peel off from the metal support, and the film thickness obtained by suppressing the elongation at the time of peeling is made uniform. It is preferable to contain a peeling aid.

  The stripping aid is at least one of acid, alcohol, metal salt, nonionic surfactant or nonreactive quaternary ammonium salt type surfactant having a linear or branched alkyl group having 8 to 22 carbon atoms. It is preferable that they are contained within a range of 0.1 to 1.0% by mass with respect to the total mass of the norbornene-based resin having a norbornane skeleton represented by the general formula (1) contained in the polarizing plate protective film. By doing so, the peelability can be improved.

  Examples of the peeling aid include alkyl sulfonates and alkyl benzene sulfonates. Examples of the salt include sodium salt, potassium salt, amine salt, ammonium salt, phosphonium salt and the like.

  Moreover, as these commercially available products, Clariant Japan Co., Ltd. Hostastat HS-1, Takemoto Yushi Co., Ltd. Elecut S-412-2, Elecut S-418, Kao Corporation Neo-Perex G65, etc. are mentioned. It is done.

  Examples of alcohols include octan-1-ol, nonan-1-ol, decan-1-ol, undecan-1-ol, dodecan-1-ol, tridecan-1-ol, tetradecan-1-ol, pentadecane- 1-ol, hexadecan-1-ol, heptadecan-1-ol, octadecan-1-ol, nonadecan-1-ol, icosan-1-ol, heneicosan-1-ol, docosan-1-ol, etc. Octadecan-1-ol (stearyl alcohol) is preferred.

  It is also useful to use a nonionic surfactant as a peeling aid, for example, polyoxyalkylene glycols such as polyoxyethylene polyoxypropylene glycol, polyoxyalkylene styrenes such as polyoxyethylene styrenated phenyl ether, and the like. Polyoxyalkylene glycols such as conjugated phenyl ether, polyoxyethylene tridecyl ether, polyoxyethylene lauryl ether, polyoxyethylene sorbitan monococoate, polyoxyethylene sorbitan monostearate, polyoxyethylene hydrogenated castor oil Nonionic surfactants, such as ester, are mentioned, These may be used independently and may use 2 or more types together. Examples of these commercially available products include Epan manufactured by Daiichi Kogyo Seiyaku Co., Ltd.

  Furthermore, it is also preferable to use a non-reactive quaternary ammonium salt type surfactant as a peeling aid, and among them, a non-reactive quaternary ammonium salt type surfactant having 2 or less methyl groups is useful. In addition, these surfactants may be used independently and may mix and use 2 or more types.

  As these non-reactive quaternary ammonium salt type surfactants, commercially available products can be used. For example, trade names “ADEKA COAL CC-36”, “ADEKA COAL CC-42” manufactured by ADEK, Daiichi Kogyo Seiyaku Co., Ltd. "Cation L-207", "Cathogen ES-L", "Cathogen ES-O", "Cathogen ES-OW", "Cathogen ES-WS-L-9", "Cathogen ES-P" , “Cathogen DDM-PG”, “Cathogen S”, “Cathogen D2”, “Cathogen BC-50” and the like.

(Impact reinforcement)
The polarizing plate protective film of the present invention preferably contains at least one of core / shell type acrylic fine particles, a styrene-conjugated diene compound, or a butyl acrylate compound as an impact reinforcing material in order to enhance impact resistance. .

  In particular, a core / shell type graft copolymer obtained by grafting a (meth) acrylic resin to a copolymer of a (meth) acrylic rubber and an aromatic vinyl compound described in JP-A-2009-84574, or an international It is preferable to contain an impact reinforcing material such as core-shell type acrylic fine particles described in JP 2009/047924 A and styrene-butadiene-based elastic organic fine particles described in JP 2013-83907 A. .

  For example, core / shell type acrylic fine particles are obtained by polymerizing a mixture of 80 to 98.9% by mass of methyl methacrylate, 1 to 20% by mass of alkyl acrylate and 0.01 to 0.3% by mass of a polyfunctional grafting agent. Obtained by polymerizing a mixture of the innermost hard layer and 75 to 98.5% by mass of an alkyl acrylate, 0.01 to 5% by mass of a polyfunctional crosslinking agent and 0.5 to 5% by mass of a polyfunctional grafting agent. It has a soft layer and an outermost hard layer obtained by polymerizing a mixture of 80 to 99% by weight of methyl methacrylate and 1 to 20% by weight of alkyl acrylate.

  The styrene-conjugated diene compound is preferably a styrene-butadiene copolymer. The copolymer may be a rubber-like elastic body or an elastic organic fine particle. Specifically, the elastic organic fine particle is preferably a core-shell type particle.

  A soft polymer contains the structural unit derived from a conjugated diene monomer, and the structural unit derived from another monomer as needed. Examples of the conjugated diene monomer include 1,3-butadiene (hereinafter sometimes simply referred to as “butadiene”), isoprene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, 2-chloro-1,3-butadiene, myrcene and the like are included, and butadiene and isoprene are preferable. Examples of other monomers include styrene components such as styrene and α-methylstyrene. The content ratio of the structural unit derived from the conjugated diene monomer in the soft polymer is usually 50% by mass or more, preferably 70% by mass or more, and more preferably 90% by mass or more.

  Examples of other polymers include a copolymer of acrylonitrile and styrene, a polymer mainly composed of a methacrylic ester such as methyl methacrylate, and the like.

  Commercially available products include, for example, Metabrene C-140A, C-215A (above, manufactured by Mitsubishi Rayon Co., Ltd.), Toughprene 126, Asaflex 800, Asaflex 825 (above, manufactured by Asahi Kasei Chemicals Co., Ltd.), TR2000, TR2250. (Above, manufactured by JSR Corporation).

  Examples of other rubber-like elastic bodies include acrylate-based rubber-like polymers, and rubber-like polymers containing acrylate-based polymers containing butyl acrylate as the main component are preferred.

[Optical characteristics of polarizing plate protective film]
In the polarizing plate protective film of the present invention, the retardation value Ro defined by the following formula (i) is in the range of 0 to 10 nm, and the retardation value Rt defined by the following formula (ii) is −10. It is in the range of -10 nm.

Formula (i)
_{Ro = (n x -n y)} × d
Formula (ii)
Rt = {(n _x + n _y ) / 2−n _z } × d
In the above formula (i) and (ii), Ro-plane direction of the retardation value of the film, Rt is the thickness direction of the retardation value of the film, n _x is a refractive index in a slow axis direction in the film plane, _ny is the refractive index in the fast axis direction in the film plane, _nz is the refractive index in the thickness direction of the film (the refractive index is measured at a wavelength of 590 nm in an environment of 23 ° C. and 55% RH), and d is the film Represents thickness (nm).

  The retardation value Ro in the in-plane direction and the retardation value Rt in the thickness direction of the film are 23 ° C. and 55% RH using an automatic birefringence meter Axoscan (Axo Scan Mueller Matrix Polarimeter: manufactured by Axometrics). The three-dimensional refractive index measurement can be performed at a wavelength of 590 nm under the above environment, and the refractive indexes nx, ny and nz obtained can be calculated.

  The retardation value Ro defined by the formula (i) defined above is in the range of 0 to 10 nm, and the retardation value Rt represented by the formula (ii) is in the range of −10 to 10 nm means in-plane It means that the retardation value Ro (nm) in the direction and the retardation value Rt (nm) in the thickness direction of the film are substantially zero polarizing plate protective films.

  The liquid crystal obtained when the retardation value Ro in the film plane of the polarizing plate protective film and the retardation value Rt in the thickness direction of the film are set to substantially zero, and bonded to the liquid crystal cell on the polarizing plate protective film side. Light leakage at the time of black display in the display device can be effectively prevented. In addition, since the thickness of the polarizing plate protective film can be reduced, the polarizing plate and the liquid crystal display device can be further reduced in thickness and weight, which is preferable.

  Although there is no restriction | limiting in particular as a method of achieving the said conditions, The method of carrying out aptitude control of the extending | stretching conditions at the time of film film formation is suitable.

[Production method of polarizing plate protective film]
As a method for producing the polarizing plate protective film of the present invention, the usual inflation method, T-die method, calendar method, cutting method, casting method, emulsion method, hot press method and the like can be used. From the standpoint of suppressing foreign matter defects, optical defects such as die lines, etc., a film casting method can be selected from a solution casting film forming method and a melt casting film forming method, and in particular, a solution casting film forming method. In addition to the effect of controlling the distribution state of the norbornene-based resin to suppress panel bend, a uniform and smooth surface can be obtained, and further, from the viewpoint of reducing haze and yellow index (YI).

<Solution casting method>
Hereinafter, the manufacture example by the solution casting method suitable for manufacture of the polarizing plate protective film of this invention is demonstrated.

  The polarizing plate protective film of the present invention is produced by using a norbornene-based resin having a norbornane skeleton represented by the general formula (1) according to the present invention, a matting agent, and, if necessary, a compound such as a polyester-based plasticizer as a solvent. A step of preparing a dope by dissolving and filtering, a step of casting the prepared dope on a belt-like or drum-like metal support to form a web, and peeling the formed web from the metal support to form a film It is performed by a step, a step of stretching and drying the film, and a step of winding the dried film into a roll after cooling.

  Hereinafter, each step will be described.

(1) Dissolution step In a dissolution vessel, the resin, and optionally other compounds are dissolved in an organic solvent mainly containing a good solvent for a norbornene-based resin while stirring to form a dope, or in the resin solution The other compound solution is mixed to form a dope which is a main solution.

  When the polarizing plate protective film of the present invention is produced by the solution casting method, the organic solvent useful for forming the dope can be used without limitation as long as it dissolves the norbornene-based resin and other additives at the same time. it can.

  For example, as the chlorinated organic solvent, methylene chloride, as the non-chlorinated organic solvent, methyl acetate, ethyl acetate, amyl acetate, acetone, tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, cyclohexanone, ethyl formate, 2,2,2-trifluoroethanol, 2,2,3,3-hexafluoro-1-propanol, 1,3-difluoro-2-propanol, 1,1,1,3,3,3-hexafluoro- Examples include 2-methyl-2-propanol, 1,1,1,3,3,3-hexafluoro-2-propanol, 2,2,3,3,3-pentafluoro-1-propanol, and nitroethane. For example, methylene chloride, methyl acetate, ethyl acetate, and acetone can be preferably used as the main solvent. Particularly preferably ethyl acetate.

  In addition to the organic solvent, the dope preferably contains a linear or branched aliphatic alcohol having 1 to 4 carbon atoms in the range of 1 to 40% by mass. When the proportion of alcohol in the dope increases, the web gels and peeling from the metal support becomes easy, and when the proportion of alcohol is small, norbornene resins and other compounds in a non-chlorine organic solvent system There is also a role to promote dissolution. In the film formation of the polarizing plate protective film of the present invention, the film is formed using a dope having an alcohol concentration in the range of 0.5 to 15.0% by mass in order to improve the flatness of the obtained polarizing plate protective film. The method to do can be applied.

  In particular, a dope in which norbornene-based resin and other compounds are dissolved in a total amount of 15 to 45% by mass in a solvent containing methylene chloride and a linear or branched aliphatic alcohol having 1 to 4 carbon atoms. A composition is preferred.

  Examples of the linear or branched aliphatic alcohol having 1 to 4 carbon atoms include methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol, and tert-butanol. Of these, methanol and ethanol are preferred because of the stability of the dope, the boiling point is relatively low, and the drying property is good.

  For dissolving norbornene-based resins or other compounds, a method carried out at normal pressure, a method carried out below the boiling point of the main solvent, a method carried out under pressure above the boiling point of the main solvent, JP-A-9-95544, JP-A-9 It is possible to use various dissolution methods such as a method using a cooling dissolution method as described in JP-A-95557 or JP-A-9-95538, a method using high pressure as described in JP-A-11-21379. In particular, a method in which the pressure is applied above the boiling point of the main solvent is preferable.

  The concentration of the norbornene resin in the dope is preferably in the range of 10 to 40% by mass. After the compound is added to the dope during or after dissolution and dissolved and dispersed, it is filtered through a filter medium, defoamed, and sent to the next step with a liquid feed pump.

  Regarding dope filtration, it is preferable to filter the dope with a filter medium having a 90% collection particle diameter of 10 to 100 times the average particle diameter of fine particles, for example, with a main filter equipped with a leaf disk filter.

  In the present invention, the filter medium used for filtration preferably has a small absolute filtration accuracy, but if the absolute filtration accuracy is too small, the filter medium is likely to be clogged, and the filter medium must be frequently replaced. There is a problem of lowering productivity.

  Therefore, in the present invention, the filter medium used for the dope preferably has an absolute filtration accuracy of 0.008 mm or less, more preferably in the range of 0.001 to 0.008 mm, and in the range of 0.003 to 0.006 mm. The filter medium is more preferable.

  There are no particular restrictions on the material of the filter medium, and normal filter media can be used. However, plastic fiber filter media such as polypropylene and Teflon (registered trademark), and metal filter media such as stainless steel fibers are used to remove fibers. This is preferable.

In the present invention, the flow rate of the dope during filtration, preferably in the range of ^{10~80kg / (h · m 2)} , more preferably ^{20~60kg / (h · m 2)} . Here, if the dope flow rate during filtration is 10 kg / (h · m ² ) or more, efficient productivity is obtained, and the dope flow rate during filtration is 80 kg / (h · m ² ) or less. For example, the pressure applied to the filter medium is appropriate, and the filter medium is preferably not damaged.

  The filtration pressure is preferably 3500 kPa or less, more preferably 3000 kPa or less, and even more preferably 2500 kPa or less. The filtration pressure can be controlled by appropriately selecting the filtration flow rate and the filtration area.

  Next, a specific configuration example for producing the polarizing plate protective film of the present invention by a solution casting method will be described with reference to the drawings. In the following description, the numerals described in parentheses after the components indicate the symbols described in the drawings.

  FIG. 1 is a schematic view showing an example of a solution casting film forming apparatus applicable to the production of a polarizing plate protective film of the present invention.

  Large dough is removed from the dope prepared in the charging kettle (41) by the filter (44), and the dope is fed to the stock kettle (42). Thereafter, various additives are added from the stock kettle (42) to the main dope dissolving kettle (1).

  Thereafter, the main dope is filtered by the main filter (3), and a matting agent dispersion, an ultraviolet absorbent additive, and the like are added in-line through the conduit (16).

  In many cases, the main dope may contain about 10 to 50% by mass of the recycled material.

  The return material is, for example, a product obtained by finely pulverizing the polarizing plate protective film of the present invention, which is generated when the polarizing plate protective film is formed. The raw material for the polarizing plate protective film exceeding the value is used.

  Moreover, as a raw material of norbornene-based resin used for dope preparation, a resin and other compounds previously pelletized can be preferably used.

(2) Casting step (2-1) Casting of dope An endless metal support that feeds the dope to a pressurizing die (30) through a pump (for example, a pressurized metering gear pump) and transfers it indefinitely. (31) A step of casting a dope from a pressure die slit to a casting position on a metal support such as a stainless steel belt or a rotating metal drum.

  The metal support (31) in the casting (casting) step preferably has a mirror-finished surface, and a stainless steel belt or a drum whose surface is plated with a casting is preferably used as the metal support. The cast width can be in the range of 1 to 4 m, preferably in the range of 1.5 to 3 m, and more preferably in the range of 2 to 2.8 m.

  The surface temperature of the metal support (31) in the casting step is set in the range of −50 ° C. to a temperature at which the solvent boils and does not foam, more preferably in the range of −30 to 100 ° C. A higher temperature is preferable because the web drying speed can be increased. However, if the temperature is too high, the web may foam and flatness may deteriorate. As preferable support body temperature, it determines suitably in the range of 0-100 degreeC, and the inside of the range of 5-30 degreeC is still more preferable. Alternatively, it is also a preferable method that the web is gelled by cooling and peeled from the drum in a state containing a large amount of residual solvent.

  Although the method in particular of controlling the temperature of a metal support body (31) is not restrict | limited, There exist the method of spraying warm air or cold air, and the method of making warm water contact the back side of a metal support body. It is preferable to use hot water because heat transfer is performed efficiently, so that the time until the temperature of the metal support (31) becomes constant is short. When using warm air, considering the temperature drop of the web due to the latent heat of vaporization of the solvent, while using warm air above the boiling point of the solvent, there is a case where wind at a temperature higher than the target temperature is used while preventing foaming. is there. In particular, it is preferable to perform drying efficiently by changing the temperature of the support and the temperature of the drying air during the period from casting to peeling.

  As the die, the pressure die (30) is preferable because the slit shape of the die portion of the die can be adjusted and the film thickness can be easily made uniform. The pressure die (30) includes a coat hanger die and a T die, and any of them is preferably used. The surface of the metal support (31) is a mirror surface. In order to increase the deposition rate, two or more pressure dies (30) may be provided on the metal support (31), and the dope amount may be divided and laminated.

(3) Solvent evaporation step The web (the dope is cast on the casting support and the formed dope film is referred to as a web) is heated on the casting support to evaporate the solvent.

  To evaporate the solvent, there are a method in which air is blown from the web side, a method in which heat is transferred from the back surface of the support by liquid, a method in which heat is transferred from the front and back by radiant heat, and the like. Well preferred. A method of combining them is also preferably used. The web on the support after casting is preferably dried on the support in an atmosphere of 40 to 100 ° C. In order to maintain the atmosphere at 40 to 100 ° C., it is preferable to apply hot air at this temperature to the upper surface of the web or to heat by means such as infrared rays.

  From the viewpoint of surface quality, moisture permeability, and peelability, it is preferable to peel the web from the support within a range of 30 to 120 seconds.

(4) Peeling process A peeling process is a process of peeling the web which the solvent evaporated on the metal support body in the peeling position (33). The peeled web is sent to the next process as a film.

  The temperature at the peeling position (33) on the metal support is preferably in the range of 10 to 40 ° C, more preferably in the range of 11 to 30 ° C.

  The amount of residual solvent at the time of peeling of the web on the metal support at the time of peeling is preferably within the range of 50 to 120% by mass depending on the strength of drying conditions, the length of the metal support, etc. When peeling at a higher residual solvent amount, if the web is too soft, the flatness at the time of peeling is impaired, and slippage and vertical stripes are likely to occur due to the peeling tension. The amount of solvent is determined.

  The amount of residual solvent in the web is defined by the following formula (I).

Formula (I)
Residual solvent amount (%) = (mass before web heat treatment−mass after web heat treatment) / (mass after web heat treatment) × 100
Note that the heat treatment for measuring the residual solvent amount represents performing heat treatment at 115 ° C. for 1 hour.

  The peeling tension when peeling the metal support and the film is usually in the range of 196 to 245 N / m. However, if wrinkles are likely to occur during peeling, the peeling may occur with a tension of 190 N / m or less. preferable.

In the present invention, the temperature at the peeling position (33) on the metal support (31) is preferably in the range of −50 to 40 ° C., more preferably in the range of 10 to 40 ° C., and 15 to 30. Most preferably, it is within the range of ° C.
(5) Drying and stretching process (Drying process)
The web obtained by peeling from the metal support is dried. The web may be dried while being transported by a large number of rollers arranged above and below, or may be dried while being transported by fixing both ends of the web with clips like a tenter dryer.

  The means for drying the web is not particularly limited, and can be performed with hot air, infrared rays, a heating roller, microwaves, or the like, but it is preferable to perform with hot air in terms of simplicity.

  The drying temperature in the web drying step is preferably equal to or lower than the glass transition temperature (Tg) of the film, and it is effective to perform a heat treatment within a range of 10 to 60 minutes at a temperature of 100 ° C. or higher. Drying is performed at a drying temperature in the range of 100 to 200 ° C, more preferably in the range of 110 to 160 ° C.

  In addition, a drying process can also be performed by dividing into a preliminary drying process and this drying process.

(Stretching process)
The polarizing plate protective film of the present invention can control the orientation of molecules in the film by being subjected to stretching treatment, and can improve planarity and obtain toughness.

  The polarizing plate protective film of the present invention is preferably stretched in the longitudinal direction (also referred to as MD direction) and / or the width direction (also referred to as TD direction), and at least 1 in the longitudinal direction or the width direction as a stretching ratio. It is preferable to stretch within a range of 0.01 to 10 times.

  The stretching operation may be performed in multiple stages. Moreover, when performing biaxial stretching, you may perform simultaneous biaxial stretching of MD direction and TD direction, and you may implement in steps. In this case, stepwise means that, for example, stretching in different stretching directions can be sequentially performed, stretching in the same direction is divided into multiple stages, and stretching in different directions is added to any one of the stages. Is also possible.

  That is, for example, the following stretching steps are possible.

-Stretch in longitudinal direction-> Stretch in width direction-> Stretch in longitudinal direction-> Stretch in longitudinal direction-Stretch in width direction-> Stretch in width direction-> Stretch in longitudinal direction-> Stretch in longitudinal direction--Stretch in width direction-> Stretching in an oblique direction In addition, simultaneous biaxial stretching includes stretching in one direction and contracting the other while relaxing the tension.

  The amount of residual solvent at the start of stretching is preferably in the range of 2 to 10% by mass.

  If the amount of residual solvent is 2% by mass or more, the film thickness deviation is small, which is preferable from the viewpoint of flatness, and if it is 10% by mass or less, surface unevenness is reduced, and the flatness is improved.

  The polarizing plate protective film of the present invention has a glass transition temperature of Tg (° C.) in the MD direction and / or TD direction, preferably in the TD direction so that the film thickness after stretching is in a desired range. Furthermore, it is preferable to stretch in a temperature range of (Tg + 15) to (Tg + 50) ° C. If it extends in the said temperature range, since a extending | stretching stress can be reduced, a haze will become low. Moreover, generation | occurrence | production of a fracture | rupture is suppressed and the polarizing plate protective film excellent in planarity is obtained. The stretching temperature is preferably within the range of (Tg + 20) to (Tg + 40) ° C.

  The polarizing plate protective film of the present invention preferably stretches the web at least in the MD direction or TD direction within a range of 1.01 to 10 times, but the stretching range is 1.1 to 10 with respect to the original width. It is preferably within the range of double, and more preferably within the range of 1.2 to 8 times. If it is in the said range, a film will become toughness, a film can be thinned, and the planarity of a film can be improved.

  In order to stretch in the MD direction, it is preferable to peel at a peeling tension of 130 N / m or more, and it is particularly preferable to peel within a range of 150 to 170 N / m. Since the web after peeling is in a high residual solvent state, stretching in the MD direction can be performed by maintaining the same tension as the peeling tension. As the web dries and the residual solvent amount decreases, the stretch ratio in the MD direction decreases.

  In addition, for the stretching in the MD direction, a roller stretching machine using a difference in peripheral speed of rollers can be used, and the stretching ratio can be calculated from the rotation speed of the belt support and the operation speed of the roller stretching machine.

  In order to stretch in the TD direction, for example, the entire drying process or a part of the process as disclosed in Japanese Patent Application Laid-Open No. 62-46625 is performed while holding the width at both ends of the web with clips or pins in the width direction. A drying method (referred to as a tenter method), among them, a tenter method using clips and a pin tenter method using pins are preferably used.

  In stretching in the TD direction, stretching in the film width direction at a stretching speed of 250 to 500% / min is preferable from the viewpoint of improving the flatness of the film.

  If the stretching speed is 250% / min or more, the planarity is improved and the film can be processed at a high speed, which is preferable from the viewpoint of production aptitude, and if it is 500% / min or less, the film is broken. Can be processed without any problem.

  A preferable stretching speed is in the range of 300 to 400% / min. The stretching speed is defined by the following formula (II).

Formula (II)
Stretching speed (% / min) = [(d ₁ / d ₂ ) −1] × 100 (%) / t
In the formula (II), d ₁ represents the width in the stretching direction of the resin film after stretching. d ₂ represents the width in the stretching direction of the resin film before stretching. t represents the time (min) required for stretching.

The in-plane retardation value Ro and the retardation value Rt in the thickness direction of the polarizing plate protective film of the present invention are 23 ° C. using an automatic birefringence meter Axoscan (Axo Scan Mueller Matrix Polarimeter: manufactured by Axometrics). environment of · 55% RH, at a wavelength of 590 nm, subjected to three-dimensional refractive index measured, resulting refractive indices _{n x,} n y, can be calculated from _{n z.}

  The polarizing plate protective film of the present invention has a retardation value (Ro) defined by the following formula (i) in the range of 0 to 10 nm, and a retardation value (Rt) defined by the following formula (ii). It is preferable when it exists in the range of -10-10nm as a polarizing plate protective film which does not require retardation especially. The polarizing plate protective film can be stretched while adjusting the stretching ratio in at least the MD direction or the TD direction.

Formula (i)
_{Ro = (n x -n y)} × d (nm)
Formula (ii)
Rt = {(n _x + n _y ) / 2−n _z } × d (nm)
Wherein, Ro-plane direction of the retardation value of the film, Rt is the thickness direction of the retardation value of the film, n _x is a refractive index in a slow axis direction in the film plane, n _y is advancing in the film plane refractive index of the axis direction, _{n z} is the thickness direction of the refractive index of the film (refractive index 23 ° C., under an environment of 55% RH, measured at a wavelength 590 nm), d represents the thickness of the film (nm).

(Knurling)
After a predetermined heat treatment or cooling treatment, it is preferable to provide a slitter and cut off the end portion before winding to obtain a good winding shape. Furthermore, it is preferable to knurling both ends of the width.

  The knurling process can be formed by pressing a heated embossing roller. Fine embossing is formed on the embossing roller, and by pressing the embossing roller, unevenness can be formed on the film and the end can be made bulky.

  It is preferable that the height of the knurling of the both width | variety both ends of the polarizing plate protective film of this invention exists in the range of 4-20 micrometers, and the width of 5-20 mm.

  In the present invention, the knurling process is preferably provided after the drying in the film forming step and before the winding.

(6) Winding step The winding step is a step of winding the film as a film after the residual solvent amount in the web is 2% by mass or less. The dimensional stability is achieved by setting the residual solvent amount to 0.4% by mass or less. A film having good properties can be obtained.

  As a winding method, a generally used method may be used, and there are a constant torque method, a constant tension method, a taper tension method, a program tension control method with a constant internal stress, and the like.

<Melt casting method>
The polarizing plate protective film of the present invention can also be formed by a melt casting method. In the melt casting method, a composition containing a norbornene-based resin having a norbornane skeleton represented by the general formula (1) according to the present invention and other compounds is heated and melted to a temperature showing fluidity, and then the fluidity. The casting of a molten material.

  In the melt casting method, the melt extrusion method is preferable from the viewpoint of mechanical strength and surface accuracy. A plurality of raw materials used for melt extrusion are usually preferably kneaded and pelletized in advance.

  The pelletization may be performed by a known method. For example, a norbornene-based resin having a norbornane skeleton represented by the general formula (1) according to the present invention and other compounds are fed to an extruder with a feeder, and are uniaxially or biaxially. It can be kneaded using an extruder, extruded into a strand from a die, water-cooled or air-cooled, and cut.

  The additives may be mixed before being supplied to the extruder, or may be supplied by individual feeders.

  A small amount of additives such as particles and antioxidants are preferably mixed in advance in order to mix uniformly.

  It is preferable to process the extruder at a temperature as low as possible so that the extruder can be pelletized so as to suppress shearing force and prevent the resin from deteriorating (molecular weight reduction, coloring, gel formation, etc.). For example, in the case of a twin screw extruder, it is preferable to rotate in the same direction using a deep groove type screw. From the uniformity of kneading, the meshing type is preferable.

  A film is formed using the pellets obtained as described above. Of course, the raw material powder can be directly supplied to the extruder by a feeder without being pelletized, and a film can be formed as it is.

  Using a single-screw or twin-screw type extruder, the pellets are melted at a temperature of about 200 to 300 ° C., filtered through a leaf disk type filter or the like to remove foreign matters, and then flowed from the T die into a film. Then, the film is nipped with a cooling roller and an elastic touch roller, and solidified on the cooling roller to form a polarizing plate protective film.

  When introducing into the extruder from the supply hopper, it is preferable to prevent oxidative decomposition or the like under vacuum or reduced pressure or in an inert gas atmosphere.

  The extrusion flow rate is preferably adjusted stably by introducing a gear pump or the like. Further, a stainless fiber sintered filter is preferably used as a filter used for removing foreign substances. Stainless steel fiber sintered filter is made by compressing the stainless steel fiber body after creating a complex intertwined state, and sintering and integrating the contact points. The density is changed depending on the thickness of the fiber and the compression amount, and filtration is performed. The accuracy can be adjusted.

  Additives such as antioxidants and particles may be mixed with the resin in advance, or may be kneaded in the middle of the extruder. In order to add uniformly, it is preferable to use a mixing apparatus such as a static mixer.

  The temperature of the polarizing plate protective film on the touch roller side when the polarizing plate protective film is nipped between the cooling roller and the elastic touch roller is preferably in the temperature range of Tg to (Tg + 110) ° C. of the film. A known roller can be used as the roller having an elastic surface used for such purposes.

  The elastic touch roller is also called a pinching rotator. A commercially available one can be used as the elastic touch roller.

  When peeling the film from the cooling roller, it is preferable to control the tension to prevent deformation of the film.

  Moreover, it is preferable that the film obtained as described above is stretched by a stretching operation after passing through the step of contacting the cooling roller.

  As a stretching method, a known roller stretching machine, a tenter or the like can be preferably used. The stretching temperature is preferably performed in the temperature range of Tg to (Tg + 60) ° C. of the norbornene-based resin constituting the film.

  Before winding, the end may be slit and cut to the width to be the product, and knurling (embossing) may be applied to both ends to prevent sticking and scratching during winding. The knurling method can be processed by heating or pressurizing using a metal ring having an uneven pattern on the side surface. In addition, since the polarizing plate protective film has deform | transformed and cannot use as a product, the holding part of the clip of the both ends of a film is normally cut out and reused.

<Physical properties of polarizing plate protective film>
(Wavelength dispersion)
The polarizing plate protective film of the present invention is a value calculated by Ro (450) / Ro (550), where the values of retardation (Ro) at wavelengths of 450 nm and 550 nm are Ro (450) and Ro (550), respectively. Is preferably less than 1.01.

(Haze)
The polarizing plate protective film of the present invention preferably has a haze value of 1.0% or less, and more preferably 0.5% or less. By setting the haze to 1.0% or less, there is an advantage that the transparency of the film becomes higher and it becomes easier to use as a film for optical applications.

  The haze value is measured with a haze meter (turbidimeter) (model: NDH 2000, manufactured by Nippon Denshoku Industries Co., Ltd.) in accordance with JIS K 7136.

(Yellow Index: YI)
In the polarizing plate protective film of the present invention, YI is preferably 1.0 or less, and more preferably 0.5 or less. By setting YI to 1.0 or less, there is an advantage that the transparency of the film becomes higher and it becomes easier to use as a film for optical applications. In particular, manufacturing the polarizing plate protective film of the present invention by a solution casting method is a preferable manufacturing method from the viewpoint of reducing YI.

  The yellow index (YI) referred to in the present invention can be determined by the method described in JIS K 7105-6.3. As a specific method for measuring the yellow index value, the color tristimulus values X, Y, and Z are obtained using a spectrophotometer U-3200 manufactured by Hitachi, Ltd. and the attached saturation calculation program, etc. The yellow index value is obtained.

Yellow index (%) = 100 (1.28X-1.06Z) / Y
(Total light transmittance)
The total light transmittance of the polarizing plate protective film of the present invention is preferably 90% or more, and more preferably 93% or more. The total light transmittance can be measured according to JIS K 7573 “Plastics—How to determine total light transmittance and total light reflectance”.

(Equilibrium moisture content)
In the polarizing plate protective film of the present invention, the equilibrium water content at 25 ° C. and 55% RH is preferably 3% or less, and more preferably 2% or less. By setting the equilibrium moisture content to 3% or less, it is preferable to easily cope with a change in humidity and to hardly change the optical characteristics and dimensions.

(Film length, width, film thickness)
The polarizing plate protective film of the present invention is preferably long, specifically, preferably has a length of about 100 to 10000 m, and is wound into a roll. Moreover, it is preferable that the width | variety of the polarizing plate protective film of this invention is 1 m or more, More preferably, it is 1.4 m or more, and it is especially preferable that it is 1.4-4 m.

  The film thickness of the polarizing plate protective film is preferably in the range of 10 to 100 μm, more preferably in the range of 10 to 40 μm, from the viewpoint of thinning the display device and productivity. If the film thickness is 10 μm or more, a certain level of film strength and retardation can be expressed. When the film thickness is 100 μm or less, the film has a desired retardation and can be applied to make the polarizing plate and the display device thinner.

(Moisture permeability)
The moisture permeability at 40 ° C. and 90% RH of the polarizing plate protective film is preferably 300 g / (m ² · day) or less, more preferably 200 g / (m ² · day) or less, and 10 to 100 g. / (M ² · day) is preferable. This is for suppressing a change in the size of the polarizer due to the transmitted water in a high temperature and high humidity environment. The moisture permeability is measured under the conditions of 40 ° C. and 90% RH in accordance with the method described in JIS Z 0208.

(Tear strength)
The tear strength of the polarizing plate protective film at 23 ° C. and 55% RH is preferably 15 mN or more, more preferably 20 mN or more, and further preferably 30 mN or more. The upper limit of the tear strength is, for example, about 50 mN.

  The tear strength of the polarizing plate protective film can be measured by the following method. That is, the polarizing plate protective film is cut out to obtain a sample film having a width of 50 mm and a length of 64 mm. The sample film is conditioned at 23 ° C. and 55% RH for 24 hours, and then the Elmendorf tear strength is measured according to ISO 6383 / 2-1983. Elmendorf tear strength can be measured using a Toyo Seiki Co., Ltd. light weight tear tester. The tear strength is determined for each of the case of tearing in the film length direction (MD direction) and the film width direction (TD direction) at 23 ° C. and 55% RH. Desired.

  The tear strength of the polarizing plate protective film can be adjusted by, for example, the molecular weight of the norbornene resin. In order to increase the tear strength, for example, the molecular weight of the norbornene resin may be increased.

<Λ / 4 retardation film>
In the polarizing plate of the present invention, a λ / 4 retardation film can be used as necessary.

  The λ / 4 retardation film refers to a film having a function of converting linearly polarized light having a specific wavelength into circularly polarized light or converting circularly polarized light into linearly polarized light. Therefore, in the λ / 4 retardation film, the in-plane retardation value Ro is substantially ¼ with respect to a predetermined wavelength of light (usually in the visible light region).

  The in-plane retardation value Ro is substantially λ / 4 for a predetermined wavelength of light (usually in the visible light region). The wavelength is 550 nm in an environment of a temperature of 23 ° C. and 55% RH. The in-plane retardation value Ro (550) measured in Step 1 is in the range of 120 to 180 nm. Under the same conditions, the in-plane retardation value Ro (550) measured at a wavelength of 450 nm is measured at a wavelength of 450 nm. ) Ratio value (Ro (450) / Ro (550)) is within the range of 0.72 to 1.05.

  Under the same conditions, the ratio of the in-plane retardation value Ro (550) measured at a wavelength of 550 nm to the in-plane retardation value Ro (650) measured at a wavelength of 650 nm (Ro (550) / Ro (650)). Is in the range of 0.83 to 1.05, but since the balance with Ro (450) / Ro (550) is important, Ro (450) / Ro (550) is 0.72-1. When it is in the range of 05, it is preferable that Ro (550) / Ro (650) is in the range of 0.83 to 1.05.

  The in-plane retardation value Ro of the film is defined by the formula (i).

  In the case of increasing the in-plane retardation value Ro (550), it is a simple means to increase the film thickness d, but it is economical, the thickness of the display device is increased, and the light extraction efficiency is decreased due to a decrease in light transmittance. From the viewpoint of

  In the λ / 4 retardation film, the film thickness d is generally in the range of 20 to 100 μm, preferably in the range of 40 to 80 μm, and in the range of 40 to 65 μm, the effect of the present invention. It is particularly preferable from the viewpoint that it can be expressed more.

  A circularly polarizing plate is obtained by laminating so that the angle between the in-plane slow axis of the λ / 4 retardation film and the transmission axis of the polarizer described later is substantially 45 °.

  In the present invention, “substantially 45 °” means within a range of 45 ± 5 °. The angle between the slow axis in the plane of the λ / 4 retardation film and the transmission axis of the polarizer is preferably in the range of 41 to 49 °, and more preferably in the range of 42 to 48 °. More preferably, it is within the range of 43 to 47 °, and most preferably within the range of 44 to 46 °.

"Polarizer"
The polarizing plate of the present invention has a first protective film T1 on the viewing side and a second protective film T2 on the other surface side with at least one of the protective film T1 and the protective film T2 sandwiching the polarizer. The polarizing plate protective film of the present invention described above is characterized. Furthermore, it is a preferable aspect that the protective film T1 or the protective film T2 contains an ultraviolet absorber, and more preferably, the protective film T1 and the protective film T2 are both polarizing plate protective films of the present invention. And an embodiment containing an ultraviolet absorber.

  As another specification, as described above, the polarizing plate protective film of the present invention has polarized light whose retardation value Ro (nm) in the in-plane direction and retardation value Rt (nm) in the thickness direction of the film are almost zero. Since it is a plate protective film, the polarizing plate protective film of the present invention is bonded as the liquid crystal cell side, that is, the second protective film T2, and a conventionally known polarizing plate protective film is bonded to the opposite surface. It can also be set as such a structure.

  As a conventionally known polarizing plate protective film applicable as one film, a commercially available cellulose ester film (for example, Konica Minoltack KC8UX, KC5UX, KC8UCR3, KC8UCR4, KC8UCR5, KC4FR, KC4KR, KC4DR, KC4SR, KC8UY, KC6U, KC6UA, KC4UY, KC4UE, KC8UE, KC8UY-HA, KC8UX-RHA, KC8UXW-RHA-C, KC8UXW-RHA-NC, KC4UXW-RHA-NC, and the like, manufactured by Konica Minolta Co., Ltd.

  FIG. 2 is a schematic cross-sectional view showing an example of the configuration of the polarizing plate of the present invention.

  In FIG. 2, the polarizing plate (101A) has a polarizer (104) sandwiched between the first protective film (T1) on the viewing side and the second protective film (T2) on the liquid crystal cell side. The structure arranged through the layers (103A and 103B) is representative, and at least one of the first protective film (T1) and the second protective film (T2) is the polarizing plate protective film of the present invention. The second protective film (T2) is preferably arranged on the liquid crystal cell side, more preferably the first protective film (T1) and the second protective film (T2). Is a structure which is a polarizing plate protective film of this invention.

  In the polarizing plate of the present invention, the protective film for polarizing plate of the present invention is appropriately surface-treated and bonded using an aqueous adhesive or an active energy ray-curable adhesive.

[Polarizer]
A polarizer is an element that passes only light having a plane of polarization in a certain direction, and a typical polarizer known at present is a polyvinyl alcohol polarizing film. The polyvinyl alcohol polarizing film includes those obtained by dyeing iodine on a polyvinyl alcohol film and those obtained by dyeing a dichroic dye.

  As the polarizer, a polarizer obtained by forming a polyvinyl alcohol aqueous solution into a film and dyeing it by uniaxial stretching or dyeing and then uniaxially stretching and then preferably performing a durability treatment with a boron compound may be used.

  The film thickness of the polarizer is in the range of 5.0 to 15.0 μm, and particularly preferably in the range of 5.0 to 10.0 μm.

  Further, the ethylene unit content described in JP-A-2003-248123, JP-A-2003-342322, etc. is 1 to 4 mol%, the degree of polymerization is 2000 to 4000, and the degree of saponification is 99.0 to 99.99 mol%. The ethylene-modified polyvinyl alcohol is also preferably used. Among these, an ethylene-modified polyvinyl alcohol film having a hot water cutting temperature of 66 to 73 ° C. is preferably used. A polarizer using this ethylene-modified polyvinyl alcohol film is excellent in polarization performance and durability, and has little color unevenness, and is particularly preferably used for a large liquid crystal display device.

  Moreover, since it is preferable to make a polarizing plate into a thin film, it is especially preferable that the thickness of a polarizer exists in the range of 2.0-15.0 micrometers from a viewpoint of making the intensity | strength of a polarizing plate, and thin film formation compatible.

  As such a thin film polarizer, a laminated film type polarizer is produced by the method described in JP2011-1000016, JP4691205, JP4751481, JP48080489. Is preferred.

[Production method of polarizing plate]
(1. Production of polarizing plate using aqueous adhesive)
The polarizing plate of the present invention can be produced by a general method. The polarizer side of the polarizing plate protective film of the present invention is subjected to surface treatment such as corona treatment, plasma treatment or excimer light treatment, and is completely saponified on at least one surface of the polarizer produced by immersion and stretching in an iodine solution. Can be bonded together using an aqueous polyvinyl alcohol solution (aqueous adhesive).

  In that case, it is preferable that the retardation film and the polarizer are similarly bonded by a completely saponified polyvinyl alcohol aqueous solution (aqueous adhesive). When a cellulose ester film is used as the retardation film, the surface is preferably saponified.

  The direction of bonding with the polarizer is preferably bonded so that the absorption axis of the polarizer and the slow axis of the polarizing plate protective film are orthogonal, for example.

(2. Production of polarizing plate using active energy ray-curable adhesive)
In the polarizing plate of this invention, it is a preferable aspect that the polarizing plate protective film of this invention and at least one surface of a polarizer are bonded by the active energy ray hardening-type adhesive agent. In that case, it is preferable that the said retardation film and polarizer are similarly bonded by the active energy ray hardening-type adhesive agent. Furthermore, it is preferable that it is bonded by the same type of active energy ray-curable adhesive.

  In the present invention, by applying an active energy ray-curable adhesive to the bonding between the polarizing plate protective film and the polarizer of the present invention, or the bonding between the other polarizing plate protective film and the polarizer, With productivity, it is easy to suppress the deformation of the polarizing plate, and it is possible to obtain characteristics with excellent flatness.

(Composition of active energy ray-curable adhesive)
Examples of the active energy ray-curable adhesive composition applicable to the production of polarizing plates include a photo radical polymerization composition utilizing photo radical polymerization, a photo cation polymerization composition utilizing photo cation polymerization, and photo radical polymerization. In addition, a hybrid composition using both photocationic polymerization and photocationic polymerization is known.

  As a radical photopolymerization type composition, a radical polymerizable compound containing a polar group such as a hydroxy group or a carboxy group described in JP-A-2008-009329 and a radical polymerizable compound not containing a polar group are contained in a specific ratio. Compositions and the like are known. In particular, the radical polymerizable compound is preferably a compound having a radical polymerizable ethylenically unsaturated bond. Preferable examples of the compound having an ethylenically unsaturated bond capable of radical polymerization include a compound having a (meth) acryloyl group. Examples of the compound having a (meth) acryloyl group include an N-substituted (meth) acrylamide compound and a (meth) acrylate compound. (Meth) acrylamide means acrylamide or methacrylamide.

  Moreover, as a photocationic polymerization type composition, as disclosed in JP 2011-08234 A, (α) a cationic polymerizable compound, (β) a photocationic polymerization initiator, and (γ) a wavelength longer than 380 nm. And an active energy ray-curable adhesive composition containing each of the components of a photosensitizer exhibiting maximum absorption in the light of (δ) and a naphthalene-based photosensitization aid. However, active energy ray-curable adhesives other than these may be used.

  As the actinic radiation curable adhesive used in the present invention, an ultraviolet curable adhesive as described in the above publication is preferably used.

  Hereinafter, an example of the manufacturing method of the polarizing plate using an active energy ray hardening-type adhesive agent is demonstrated.

As a manufacturing process of the polarizing plate of the present invention, mainly,
1) An adhesive application step of applying an active energy ray-curable adhesive to at least one of the adhesive surfaces of the polarizer and the polarizing plate protective film of the present invention;
2) A bonding step in which a polarizer and a polarizing plate protective film are bonded and bonded together via an adhesive layer;
3) A curing step of curing the adhesive layer in a state where the polarizer and the polarizing plate protective film are bonded via the adhesive layer,
Can be mentioned. Moreover, you may have the pre-process process which carries out an easy adhesion process with respect to the surface which adhere | attaches the polarizer of a polarizing plate protective film.

(Pretreatment process)
In the pretreatment step, an easy adhesion treatment is performed on the surface of the polarizing plate protective film adhered to the polarizer. When the polarizing plate protective film and the retardation film are bonded to both surfaces of the polarizer via an active energy ray curable adhesive, an easy adhesion treatment is applied to each bonding surface of the polarizing plate protective film. .

  In the adhesive application step, which is the next step, the surface subjected to the easy adhesion treatment is treated as a bonding surface with the polarizer, and therefore, the both surfaces of the polarizing plate protective film are bonded to the active energy ray-curable resin layer. An easy adhesion treatment is applied to the surface. Examples of the easy adhesion treatment include corona treatment, plasma treatment, and excimer light treatment.

(Adhesive application process)
In the adhesive application step, the active energy ray-curable adhesive is applied to at least one surface side of the adhesive surfaces of the polarizer and the polarizing plate protective film. When applying an active energy ray hardening-type adhesive directly on the surface of a polarizer or a polarizing plate protective film, there is no special limitation in the coating method. For example, various wet coating methods such as a doctor blade, a wire bar, a die coater, a comma coater, and a gravure coater can be used. Moreover, after casting an active energy ray hardening-type adhesive between a polarizer and a polarizing plate protective film, the method of pressurizing with a roller etc. and spreading uniformly can also be utilized.

(Bonding process)
After apply | coating an active energy ray hardening-type adhesive agent by said method, it processes by a bonding process. In this bonding step, for example, when an active energy ray-curable adhesive is applied to the surface of the polarizer in the previous application step, a polarizing plate protective film is superimposed there. When the active energy ray-curable adhesive is applied to the surface of the polarizing plate protective film in the previous application step, a polarizer is superimposed thereon. Moreover, when an active energy ray hardening-type adhesive agent is cast between a polarizer and a polarizing plate protective film, a polarizer and a polarizing plate protective film are piled up in that state. When a polarizing plate protective film and a retardation film are bonded to both sides of a polarizer, and both surfaces use an active energy ray-curable adhesive, an active energy ray-curable adhesive is applied to both sides of the polarizer. A polarizing plate protective film and a retardation film are superimposed on each other. Usually, in this state, both sides (when a polarizing plate protective film is superimposed on one side of the polarizer, the polarizing plate protective film and the retardation film are provided on both sides of the polarizer and the polarizing plate protective film side. In the case of superimposing, pressure is applied between the polarizing plate protective film and the retardation film side of both surfaces with a roller or the like. As the material of the roller, metal, rubber or the like can be used. The rollers arranged on both sides may be made of the same material or different materials.

(Curing process)
In the curing step, an active energy ray curable adhesive is irradiated with active energy rays, and a cationic polymerizable compound (for example, an epoxy compound or an oxetane compound) or a radical polymerizable compound (for example, an acrylate compound or an acrylamide compound). The active energy ray-curable resin layer containing the compound or the like is cured, and the polarizer and the polarizing plate protective film, or the polarizer and the retardation film are overlapped with each other via the active energy ray-curable adhesive. When bonding a polarizing plate protective film to the single side | surface of a polarizer, you may irradiate an active energy ray from either a polarizer side or a polarizing plate protective film side. In addition, when a polarizing plate protective film and a retardation film are bonded to both sides of the polarizer, the polarizing plate protective film and the retardation film are overlaid on both sides of the polarizer via an active energy ray-curable adhesive, respectively. Therefore, it is advantageous to irradiate active energy rays and simultaneously cure the active energy ray-curable adhesive on both sides.

  Visible light, ultraviolet rays, X-rays, electron beams, etc. can be used as the active energy rays applied for curing, but electron beams and ultraviolet rays are generally preferred because they are easy to handle and have a sufficient curing rate. Used.

  As the ultraviolet light source, for example, a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultrahigh-pressure mercury lamp, a carbon arc lamp, a metal halide lamp, a xenon lamp, or the like can be used. Further, an ArF excimer laser, a KrF excimer laser, an excimer lamp, synchrotron radiation, or the like can also be used. Among these, an ultrahigh pressure mercury lamp, a high pressure mercury lamp, a low pressure mercury lamp, a xenon arc, and a metal halide lamp are preferably used.

  Further, as the electron beam, 50 to 1000 keV emitted from various electron beam accelerators such as a cockroft Walton type, a bandegraph type, a resonance transformation type, an insulation core transformation type, a linear type, a dynamitron type, and a high frequency type, preferably 100 Mention may be made of electron beams having an energy in the range of ˜300 keV.

  Any appropriate condition can be adopted as the electron beam irradiation condition as long as the adhesive can be cured. For example, in the electron beam irradiation, the acceleration voltage is preferably in the range of 5 to 300 kV, more preferably in the range of 10 to 250 kV. If the acceleration voltage is 5 kV or more, the electron beam can reach the adhesive sufficiently to obtain the desired curing conditions, and if the acceleration voltage is 300 kV or less, the penetration force through the bonding unit becomes excessively strong. It can suppress that a transparent polarizing plate protective film and a polarizer are damaged.

  As an irradiation dose, it exists in the range of 5-100 kGy, More preferably, it exists in the range of 10-75 kGy. When the irradiation dose is 5 kGy or more, the active energy ray-curable adhesive is sufficiently cured. When the irradiation dose is 100 kGy or less, the polarizing plate protective film and the polarizer are not damaged, and the mechanical strength is reduced. Changes can be prevented, and predetermined optical characteristics can be obtained.

Any appropriate conditions can be adopted as the irradiation condition of the ultraviolet rays as long as the active energy ray-curable adhesive can be cured. The dose of ultraviolet rays is preferably in accumulated light amount is within the range of 50~1500mJ / cm ^2, and even more preferably in the range of 100 to 500 mJ / cm ^2.

  When performing the said manufacturing method by a continuous line, although a line speed is based on the hardening time of an active energy ray hardening-type adhesive agent, Preferably it exists in the range of 1-500 m / min, More preferably, it is the range of 5-300 m / min. Of these, it is more preferably within a range of 10 to 100 m / min. If the line speed is 1 m / min or more, appropriate productivity can be secured, damage to the transparent polarizing plate protective film can be suppressed, and a polarizing plate that can withstand a durability test can be produced. . Moreover, if the line speed is 500 m / min or less, the resulting adhesive is sufficiently cured, and the desired adhesiveness can be obtained.

  In the polarizing plate obtained as described above, the thickness of the active energy ray-curable adhesive layer is not particularly limited, but is usually in the range of 0.01 to 10 μm, preferably 0.5 to 5 μm. Within range.

<Liquid crystal display device>
By using the polarizing plate on which the polarizing plate protective film of the present invention is bonded to a liquid crystal display device, the liquid crystal display device of the present invention excellent in various visibility can be produced.

  The polarizing plate of the present invention can be used for liquid crystal display devices of various drive systems such as STN, TN, OCB, HAN, VA (MVA, PVA), IPS, OCB and the like. Preferably, the IPS liquid crystal display device requires a thin polarizing plate.

  In the liquid crystal display device, usually two polarizing plates, a polarizing plate on the viewing side and a polarizing plate on the backlight side, are used, but it is also preferable to use the polarizing plate of the present invention as both polarizing plates. It is also preferable to use as.

  The direction of bonding of the polarizing plate in the IPS liquid crystal display device can be performed with reference to JP-A-2005-234431.

  The liquid crystal cell used in the present invention includes a liquid crystal layer and a pair of substrates sandwiching the liquid crystal layer, and the pair of substrates is a glass substrate having a thickness in the range of 0.3 to 0.7 mm. From the viewpoint of reducing the thickness and weight of the liquid crystal display device, it is preferable.

  FIG. 3 is a schematic cross-sectional view showing an example of the configuration of the liquid crystal display device (100) in which the polarizing plates (101A) and (101B) of the present invention described above are arranged on both surfaces of the liquid crystal cell (101C).

  In FIG. 3, both surfaces of the liquid crystal layer (107) are sandwiched between glass substrates (108A and 108B) as transparent substrates to form a liquid crystal cell (101C), and the respective surfaces of the respective glass substrates (108A and 108B). In addition, the polarizing plates (101A and 101B) having the configuration shown in FIG. 2 are arranged via the adhesive layer (106) to constitute the liquid crystal display device (100).

  In the said polarizing plate (101A and 101B), it is preferable that the polarizing plate protective film of this invention is bonded by the position of at least polarizing plate protective film 102A, 102B or 105A, 105B. The polarizing plate protective film is bonded to the polarizers 104A and 104B by ultraviolet curable adhesives 103A to 10D, respectively.

  For example, when the IPS liquid crystal display device is provided, the polarizing plate protective films 105A (T2) and 105B (T3) are preferably the polarizing plate protective films of the present invention.

  The liquid crystal cell (101C) is configured by arranging an alignment film, a transparent electrode, and glass substrates (108A and 108B) on both sides of a liquid crystal substance.

  By providing the liquid crystal display device with the polarizing plate of the present invention excellent in durability, flatness, etc., it is possible to make it difficult for panel bends to occur even if the glass substrate constituting the liquid crystal cell is thinned. A liquid crystal display device in which thinning is achieved can be obtained.

  Examples of the material constituting the glass substrate (108A and 108B) that can be used for the liquid crystal cell (101C) include soda lime glass and silicate glass, and silicate glass is preferable. Specifically, silica glass or borosilicate glass is more preferable.

  The glass constituting the glass substrate is preferably a non-alkali glass that does not substantially contain an alkali component, specifically, a glass having an alkali component content of 1000 ppm or less. The content of the alkali component in the glass substrate is preferably 500 ppm or less, and more preferably 300 ppm or less. In a glass substrate containing an alkali component, substitution of cations occurs on the film surface, and soda blowing phenomenon tends to occur. Thereby, the density of the film surface layer is likely to decrease, and the glass substrate is easily damaged.

  It is preferable that the thickness of the glass substrate (108A and 108B) of the liquid crystal cell which comprises a liquid crystal display device exists in the range of 0.3-0.7 mm. Such a thickness is preferable in that it can contribute to the thinning of the liquid crystal display device.

  The glass substrate can be formed by a known method such as a float method, a down draw method, an overflow down draw method or the like. Of these, the overflow downdraw method is preferred because the surface of the glass substrate does not come into contact with the molded member during molding and the surface of the resulting glass substrate is hardly damaged.

  Such a glass substrate can also be obtained as a commercial product. For example, non-alkali glass AN100 (thickness 500 μm) manufactured by Asahi Glass Co., Ltd., glass substrate EAGLE XG (r) Slim (thickness manufactured by Corning) 300 μm, 400 μm, etc.), a glass substrate (thickness: 100 to 200 μm) manufactured by Nippon Electric Glass Co., Ltd., and the like.

  Further, the polarizing plates (101A, 101B) as shown in FIG. 3 and the glass base materials (108A, 108B) constituting the liquid crystal cell (101C) are bonded via an adhesive layer (106).

  As the adhesive layer, a double-sided tape, for example, a 25 μm-thick double-sided tape manufactured by Lintec (baseless tape MO-3005C) or the like, or a composition used for forming the actinic ray curable resin layer is applied. Can do.

  In addition to the effects of the present invention, the liquid crystal display device using the polarizing plate of the present invention has advantages such as excellent adhesion between layers, excellent resistance to fading, resistance to egg unevenness of display images, and the like.

  Bonding between the surface of the polarizing plate on the side of the retardation film and at least one surface of the liquid crystal cell is performed by a known method. Depending on the case, it may be bonded through an adhesive layer.

  By using the polarizing plate of the present invention, panel bend is suppressed and a liquid crystal display device excellent in visibility such as display unevenness and front contrast is obtained even in the case of a large-screen liquid crystal display device having a screen size of 30 or more. be able to.

<< Use of polarizing plate protective film >>
The polarizing plate protective film of the present invention can be used as a polarizing plate protective film for various display devices such as a liquid crystal display device and an organic electroluminescence display device. The polarizing plate protective film of the present invention can also serve as a retardation film.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.

Example 1
<< Production of polarizing plate protective film >>
(Preparation of polarizing plate protective film 101)
<Preparation of dope (D-1)>
The following composition was put into a mixing tank, heated and stirred to dissolve each component, and then filtered through a filter paper having an average pore size of 34 μm and a sintered metal filter having an average pore size of 10 μm to prepare a dope (D-1).

Norbornene resin 1 (weight average molecular weight: 120,000) 100 parts by mass Dichloromethane 200 parts by mass Ethanol 10 parts by mass

<Web formation>
The dope (D-1) prepared above was cast on a film formation line, dried on a metal support until the dope (D-1) had self-supporting properties, and then peeled off as a web and introduced into a tenter.

<Preparation of polarizing plate protective film>
Next, the film was stretched and conveyed in the width direction (TD) with a tenter at a stretching ratio of 5% and a temperature in the tenter of 140 ° C. Immediately after leaving the tenter, the roller was conveyed at a tension of 100 N / m, and further dried at 140 ° C., and the film was wound up at a winding length of 4000 m to prepare a polarizing plate protective film 101. The dry film thickness of the polarizing plate protective film 101 was 5.0 μm. Note that a release film was applied to the polarizing plate protective film 101. As the peelable peelable film, a polyethylene terephthalate film with adhesive “Mastuck NBO-0424” (manufactured by Fujimori Kogyo Co., Ltd., thickness: 68 μm) was used.

<Measurement of retardation value>
About the produced polarizing plate protective film 101, the retardation value Ro in the film plane and the retardation value Rt in the film thickness direction are measured using an automatic birefringence meter Axoscan (Axo Scan Mueller Matrix Polarimeter: manufactured by Axometrics). using, an environment of 23 ℃ · 55% RH, at a wavelength of 590 nm, subjected to three-dimensional refractive index measured, resulting refractive indices _{n x,} n y, the results calculated from _{n z,} Ro is 5 nm, Rt Was 5 nm.

(Preparation of polarizing plate protective films 102-104)
In producing the polarizing plate protective film 101, polarizing plate protective films 102 to 104 were produced in the same manner except that the dry film thickness was changed from 5.0 μm to 10.0 μm, 15.0 μm, and 20.0 μm, respectively. .

(Preparation of polarizing plate protective films 105-108)
In preparation of the said polarizing plate protective films 101-104, it is the same except having added R812 which is a mat agent so that it may become 0.10 mass% with respect to the norbornene-type resin 1 using the fine particle addition liquid 1 prepared below. Thus, polarizing plate protective films 105 to 108 were produced. Note that the polarizing plate protective film 105 was not provided with a release film.

  The polarizing plate protective films 105 to 108 measured by the above method had Ro of 5 nm and Rt of 5 nm.

<Preparation of fine particle additive solution 1>
(Preparation of fine particle additive solution)
Fine particles (Aerosil R812: manufactured by Nippon Aerosil Co., Ltd., primary average particle diameter: 7 nm, abbreviation: R812) 4 parts by mass Dichloromethane 48 parts by mass Ethanol 48 parts by mass It was.

  Furthermore, after dispersing with an attritor, filtration was performed with Finemet NF manufactured by Nippon Seisen Co., Ltd. to prepare a fine particle additive solution 1.

(Preparation of polarizing plate protective films 109 to 112)
In the production of the polarizing plate protective films 105 to 108, the polarizing plate protective films 109 to 112 were produced in the same manner except that the addition amount of R812 as a matting agent to the norbornene resin 1 was changed to 0.30% by mass. did.

(Preparation of polarizing plate protective films 113 to 116)
In the production of the polarizing plate protective films 105 to 108, the polarizing plate protective films 113 to 116 were produced in the same manner except that the addition amount of R812 as the matting agent to the norbornene resin 1 was changed to 0.50% by mass. did.

(Preparation of polarizing plate protective films 117-128)
In the production of the polarizing plate protective films 105 to 116, the polarizing plate was similarly changed except that the matting agent was changed from R812 to Aerosil R972V (abbreviation: R972V, manufactured by Toshin Kasei Co., Ltd., primary average particle size: 16 nm). Protective films 117 to 128 were produced.

(Preparation of polarizing plate protective films 129 to 132)
In the production of the polarizing plate protective film 110, the Ro value was similarly adjusted except that the uniaxial stretching ratio in the width direction (TD) in the tenter during film formation was appropriately adjusted to be Ro described in Table 2. Polarizing plate protective films 129 to 132 having a thickness of 20 nm, 0 nm, 10 nm, and 15 nm were prepared.

(Preparation of polarizing plate protective films 133-136)
In preparation of the polarizing plate protective film 110, biaxial stretching that simultaneously stretches in the width direction (TD) and the longitudinal direction (MD) instead of the uniaxial stretching method in the width direction (TD) in the tenter during film formation. Polarizing plate protective films 133 to 136 were produced in the same manner except that the Rt values were changed to −15 nm, −10 nm, 10 nm, and 15 nm, respectively, by changing to the method and appropriately adjusting the stretching conditions.

(Preparation of polarizing plate protective films 137 to 140)
In the production of the polarizing plate protective film 122, the Ro value is the same except that the uniaxial stretching ratio in the width direction (TD) in the tenter during film formation is appropriately adjusted and set to Ro described in Table 2. Polarizing plate protective films 137 to 140 having a thickness of 20 nm, 0 nm, 10 nm, and 15 nm were prepared.

(Preparation of polarizing plate protective films 141-144)
In preparation of the polarizing plate protective film 122, biaxial stretching that simultaneously stretches in the width direction (TD) and the longitudinal direction (MD) instead of the uniaxial stretching method in the width direction (TD) in the tenter during film formation. Polarizing plate protective films 141 to 144 were prepared in the same manner except that the Rt values were changed to −15 nm, −10 nm, 10 nm, and 15 nm, respectively, by changing the method and appropriately adjusting the stretching conditions.

(Preparation of polarizing plate protective film 145)
In the production of the polarizing plate protective film 106, a polarizing plate protective film 145 was produced in the same manner except that the amount of R812 as a matting agent added to the norbornene resin 1 was changed to 0.70% by mass.

(Preparation of polarizing plate protective film 146)
In the production of the polarizing plate protective film 118, a polarizing plate protective film 146 was produced in the same manner except that the amount of R972V, which is a matting agent, added to the norbornene resin 1 was changed to 0.70% by mass.

(Preparation of polarizing plate protective film 147)
The production of the polarizing plate protective film 106 is the same except that the norbornene resin 2 in which the alkyl group of the side chain (R) in the norbornene resin 1 is changed from a methyl group to an ethyl group (—C ₂ H ₅ ) is used. Thus, a polarizing plate protective film 147 was produced.

(Preparation of polarizing plate protective film 148)
In the preparation of the polarizing plate protective film 106, except that the alkyl groups of the side chains (R) in the norbornene-based resin 1, was used norbornene resin 3 was changed from methyl n- propyl (-C 3 _{H 7)} In the same manner, a polarizing plate protective film 148 was produced.

(Preparation of polarizing plate protective film 149)
In the preparation of the polarizing plate protective film 106, except that the alkyl groups of the side chains (R) in the norbornene-based resin 1, was used norbornene resin 4 was changed from methyl n- butyl group (-C 4 _{H 9)} In the same manner, a polarizing plate protective film 149 was produced.

<Production of polarizing plate>
Polarizing plates 101 to 149 were prepared according to the following method.

(Production of polarizer)
A 30 μm thick polyvinyl alcohol film having an average polymerization degree of 2400 and a saponification degree of 99.9 mol% was immersed in warm water at 30 ° C. for 60 seconds to swell. Subsequently, the obtained polyvinyl alcohol film was immersed in an aqueous solution of 0.3% by mass of iodine / potassium iodide (mass ratio = 0.5 / 8) and dyed while being stretched up to 3.5 times. Thereafter, the obtained polyvinyl alcohol film was stretched in a boric acid ester aqueous solution at 65 ° C. so that the total stretching ratio was 6.0 times. Thereafter, the obtained polyvinyl alcohol film was dried in an oven at 40 ° C. for 3 minutes to obtain a polarizer having a thickness of 10 μm.

(Preparation of polarizing plate)
On the surface of the polarizing film, 100 parts of an acrylic resin comprising 90% by mass of n-butyl acrylate, 7% by mass of ethyl acrylate, and 3% by mass of acrylic acid, and trimethylolpropane (3 mol) of tolylene diisocyanate (3 mol) 1 mol) Using the pressure-sensitive adhesive obtained by mixing 2 parts of a cross-linking agent composed of a 75% by mass ethyl acetate solution of the adduct, the above-prepared polarizing plate protective film was prepared as T2 (105A) shown in FIG. The commercially available triacetyl cellulose film (thickness 40 μm, manufactured by Konica Minolta Co., Ltd.) is adhered to one side of the polarizer (104) at the position T1 (102A) shown in FIG. Irradiate from the first protective film side so that the integrated light quantity at a wavelength of ˜320 nm is 320 mJ / cm ^2, and cure the adhesive on both sides. Each polarizing plate was obtained.

<< Evaluation of polarizing plate protective film >>
[Evaluation of film surface quality 1]
After cutting the above-mentioned polarizing plate protective film to a size of 1m x 1m, under the fluorescent lamp and the green lamp, there are defects such as foreign matter, scratches, pressed marks, streaks, unevenness, etc. generated on the surface during film formation. The presence or absence was visually observed and ranked according to the following criteria.

○ Defects are not seen at all, and the surface quality is extremely good. × Defects are slightly noticeable on the film surface. Depending on the application field of the film, the quality is a practical problem.
[Preparation of polarizing plate]
Polarizing plates 101 to 149 were prepared according to the following method.

(Production of polarizer)
A 30 μm thick polyvinyl alcohol film having an average polymerization degree of 2400 and a saponification degree of 99.9 mol% was immersed in warm water at 30 ° C. for 60 seconds to swell. Subsequently, the obtained polyvinyl alcohol film was immersed in an aqueous solution of 0.3% by mass of iodine / potassium iodide (mass ratio = 0.5 / 8) and dyed while being stretched up to 3.5 times. Thereafter, the obtained polyvinyl alcohol film was stretched in a boric acid ester aqueous solution at 65 ° C. so that the total stretching ratio was 6.0 times. Thereafter, the obtained polyvinyl alcohol film was dried in an oven at 40 ° C. for 3 minutes to obtain a polarizer having a thickness of 10 μm.

(Preparation of polarizing plate sample)
On the surface of the polarizing film, 100 parts of an acrylic resin comprising 90% by mass of n-butyl acrylate, 7% by mass of ethyl acrylate, and 3% by mass of acrylic acid, and trimethylolpropane (3 mol) of tolylene diisocyanate (3 mol) 1 mol) Using the pressure-sensitive adhesive obtained by mixing 2 parts of a cross-linking agent composed of a 75% by mass ethyl acetate solution of the adduct, the above-prepared polarizing plate protective film was prepared as T2 (105A) shown in FIG. The commercially available triacetyl cellulose film (thickness 40 μm, manufactured by Konica Minolta Co., Ltd.) is adhered to one side of the polarizer (104) at the position T1 (102A) shown in FIG. Irradiate from the first protective film side so that the integrated light quantity at a wavelength of ˜320 nm is 320 mJ / cm ^2, and cure the adhesive on both sides. Each polarizing plate was obtained.

[Evaluation of process warpage 1]
Each of the produced polarizing plates is used in an environment of 23 ° C. and 55% RH so that the polarizing plate protective film T2 (105A) is on the glass plate side by using an adhesive on a glass plate having a thickness of 100 μm and 10 cm × 10 cm. The sample for a measurement was produced.

  Next, the measurement sample was allowed to stand for 24 hours in an environment of 23 ° C. and 80% RH, and then allowed to stand on a flat metal plate, and the height of unevenness due to curling of the sample sample from the metal plate surface was measured. If the sample sample was a convex curl, the maximum height from the metal surface was measured, and if the sample sample was a concave curl, the maximum height from the metal surface at the end was measured. Next, the process warpage 1 was determined according to the following criteria.

◎ The height of the unevenness is less than 5 mm. ○ The height of the unevenness is 5 mm or more and less than 10 mm. × The height of the unevenness is 10 mm or more. [Evaluation of Thermal Warpage 1]
Using a sample for measurement similar to that produced in the evaluation of the process warp, after heat treatment for 500 hours in an environment of 85 ° C., the unevenness of the sample sample is measured in the same manner as in the evaluation for the process warp. The thermal warpage 1 was evaluated according to the following criteria.

◎ The height of the unevenness is less than 5 mm ○ The height of the unevenness is 5 mm or more and less than 10 mm × The height of the unevenness is 10 mm or more [Evaluation of viewing angle characteristics]
(Production of liquid crystal display panel)
The polarizing plate made by LG Electronics (29UM57-P) was peeled off, and each of the prepared polarizing plates was bonded and used. Specifically, as shown in FIG. 3, two polarizing plates (101A, 101B) are bonded to both sides of a 29UM57-P liquid crystal cell (101C), and the above-prepared polarizing plate protective film (FIG. Each liquid crystal display panel was manufactured by pasting through an adhesive layer so that 105A and 105B) in FIG.

(Evaluation)
When a white image was displayed on the liquid crystal display panel, the Y value of the XYZ display system in the azimuth angle 45 ° direction and polar angle 60 ° direction of the display screen was measured by a product name “EZ Contrast 160D” manufactured by ELDIM. Similarly, the Y value of the XYZ display system in the azimuth angle 45 ° direction and polar angle 60 ° direction of the display screen when a black image was displayed on the liquid crystal display panel was measured. Then, the contrast ratio “YW / YB” in the oblique direction was calculated from the Y value (YW) in the white image and the Y value (YB) in the black image. The contrast ratio was measured in a dark room at a temperature of 23 ° C. and a relative humidity of 55%. Based on the measured contrast ratio, viewing angle characteristics were evaluated according to the following criteria.

○ Contrast ratio is 80 or more x Contrast ratio is less than 80 Table 3 shows the results obtained.

  As is clear from the results shown in Table 3, the polarizing plate protective film of the present invention is free from defects and has excellent surface quality as compared to the comparative example, and incorporates the polarizing plate protective film into the polarizing plate. Thus, it can be seen that the process warp resistance and the thermal warp resistance are excellent and the viewing angle characteristics are good.

Example 2
<< Production of polarizing plate protective film >>
(Preparation of polarizing plate protective film 110A)
In preparation of the polarizing plate protective film 106 described in Example 1, the following ultraviolet absorber TINUVIN Ti928 (manufactured by BASF Japan, abbreviation: Ti928) was added to the norbornene-based resin 1 except that 3.5% by mass was added. Similarly, a polarizing plate protective film 110A was produced.

(Preparation of polarizing plate protective film 110B)
In the production of the polarizing plate protective film 106 described in Example 1, except that 7.0% by mass of the ultraviolet absorber TINUVIN Ti928 (manufactured by BASF Japan, abbreviated as Ti928) was added to the norbornene-based resin 1. Similarly, a polarizing plate protective film 110B was produced.

<Production of polarizing plate>
In the production of the polarizing plate 110 described in Example 1, in the same manner except that the configuration of the polarizing plate protective film T1 on the viewing side and the polarizing plate protective film T2 on the liquid crystal cell side was changed to the combination shown in Table 4, Polarizers 201 to 206 were produced.

<< Evaluation of polarizing plate protective film: Evaluation of film surface quality 1 >>
About the upper polarizing plate protective film 110 produced in Example 1 and the produced polarizing plate protective films 110A and 110B, the film surface quality 1 was evaluated in the same manner as in the method described in Example 1.

<< Evaluation of polarizing plate >>
Polarizers 201 to 207 were produced in the same manner as in the production of the polarizing plate of Example 1, with the combination of the polarizing plate protective film T2 (liquid crystal cell side) and the polarizing plate protective film T1 (viewing side) shown in Table 4. .

[Evaluation of process warpage 2]
Each of the produced polarizing plates is used in an environment of 23 ° C. and 55% RH so that the polarizing plate protective film T2 (105A) is on the glass plate side by using an adhesive on a glass plate having a thickness of 100 μm and 10 cm × 10 cm. The sample for a measurement was produced.

  Next, the measurement sample was allowed to stand for 72 hours in an environment of 30 ° C. and 80% RH, and then allowed to stand on a flat metal plate, and the height of the unevenness due to curling of the sample sample from the metal plate surface was measured. If the sample sample was a convex curl, the maximum height from the metal surface was measured, and if the sample sample was a concave curl, the maximum height from the metal surface at the end was measured. Next, the process warpage 2 was determined according to the following criteria. If the rank was Δ or more, it was determined that the quality was acceptable in practice.

◎ The height of the unevenness is less than 3 mm ○ The height of the unevenness is 3 mm or more and less than 6 mm △ The height of the unevenness is 6 mm or more and 10 mm or less × The height of the unevenness is 10 mm or more [Evaluation of thermal warpage 2]
Using a measurement sample similar to that produced in the process warpage evaluation, after performing heat treatment for 600 hours in an environment at 90 ° C., the unevenness of the sample sample is measured in the same manner as in the process warpage evaluation. The thermal warpage 2 was evaluated according to the following criteria.

◎ The height of the unevenness is less than 3 mm ○ The height of the unevenness is 3 mm or more and 6 mm or less △ The height of the unevenness is 6 mm or more and less than 10 mm × The height of the unevenness is 10 mm or more [Evaluation of viewing angle characteristics]
The viewing angle characteristics were evaluated in the same manner as in the method described in Example 1.

  Table 4 shows the results obtained as described above.

  As is clear from the results shown in Table 4, in the polarizing plate protective film of the present invention, an ultraviolet absorber is added to either T2 or T1, more preferably an ultraviolet absorber to both T2 and T1. In particular, it can be seen that the process warpage resistance and the heat warpage resistance are improved.

Example 3
<< Production of polarizing plate protective film >>
[Preparation of Polarizing Plate Protective Film 301]
In the production of the polarizing plate protective film 110 described in Example 1, the following polyester plasticizer A (phthalic acid: adipic acid = 5: 5, terminal = benzoic acid, number average molecular weight: 500) was used as a plasticizer. A polarizing plate protective film 301 was produced in the same manner except that 1.0% by mass was added to the system resin 1.

[Preparation of polarizing plate protective films 302 to 304]
In the production of the polarizing plate protective film 301, the polarizing plate protective film 302 was similarly obtained except that the addition amount of the polyester-based plasticizer A was changed to 3.0% by mass, 5.0% by mass, and 10% by mass, respectively. -304 were made.

[Preparation of polarizing plate protective film 305]
In the production of the polarizing plate protective film 110 described in Example 1, as a plasticizer, the following polyester plasticizer B (terephthalic acid: succinic acid = 7: 3, terminal = p-oxy-benzoic acid, number average molecular weight: 600) The polarizing plate protective film 305 was produced in the same manner except that 1.0 mass% was added to the norbornene-based resin 1.

[Preparation of polarizing plate protective films 306 to 308]
In the production of the polarizing plate protective film 305, the polarizing plate protective film 306 was similarly obtained except that the addition amount of the polyester-based plasticizer B was changed to 3.0% by mass, 5.0% by mass, and 10% by mass, respectively. -308 were produced.

<Production of polarizing plate>
In the production of the polarizing plate 110 described in Example 1, the polarizing plates 301 to 308 were produced in the same manner except that the polarizing plate protective film T2 on the liquid crystal cell side was changed to the produced polarizing plate protective films 301 to 308. did.

<< Evaluation of polarizing plate protective film: Evaluation of film surface quality 1 >>
About the upper polarizing plate protective film 110 produced in Example 1 and the produced polarizing plate protective films 301 to 308 in the same manner as in the method described in Example 1, evaluation of film surface quality 1 and the following are described. The film surface quality 2 was evaluated.

[Evaluation of film surface quality 2]
About the produced polarizing plate protective films 301-308 and the polarizing plate protective film 110 produced in Example 1, each surface is observed with a scanning electron microscope (1000 times), and the uneven | corrugated state of the film surface is observed, The film surface quality 2 (surface smoothness) was evaluated according to the following criteria. In the present invention, if it is Δ or more, it is determined that the quality is practically acceptable.

◎ Very uneven surface with little unevenness ○ Very weak unevenness on the surface, but slightly flat, but good flatness △ Weak unevenness is observed on the surface, but practically acceptable It is a quality × Strong irregularities occur frequently on the surface, and it is a quality that poses a problem with flatness 《Evaluation of polarizing plate》
About the polarizing plate 110 produced in Example 1, and the produced said polarizing plates 301-308, it carried out similarly to the method as described in Example 1, and evaluated the process curvature 1, the thermal curvature 1, and the viewing angle characteristic.

  Table 5 shows the results obtained as described above.

  As is clear from the results shown in Table 5, in the polarizing plate protective film of the present invention, by allowing the polyester plasticizer to coexist, the fine uneven structure on the film surface is further reduced and the polarizing plate has excellent flatness. A protective film can be obtained.

DESCRIPTION OF SYMBOLS 1 Melting pot 3, 6, 12, 15 Filter 4, 13 Stock tank 5, 14 Liquid feed pump 8, 16 Pipe | tube 10 Ultraviolet absorber preparation pot 20 Merge pipe 21 Mixer 30 Pressure die 31 Metal support 32 Web 33 Peeling position 34 Tenter device 35 Roller drying device 41 Feeding pot 42 Stock pot 43 Pump 44 Filter 100 Liquid crystal display device 101A, 101B Polarizing plate 101C Liquid crystal cell 102A Polarizing plate protective film T1
102B Polarizing plate protective film T4
103A, 103B, 103C, 103D UV curable adhesive 104A, 104B Polarizer 105A Polarizing plate protective film T2
105B Polarizing plate protective film T3
106 Adhesive layer 107 Liquid crystal layer 108A, 108B Glass substrate BL Backlight

Claims (6)

Containing a norbornene-based resin having a norbornane skeleton represented by the following general formula (1), and a matting agent;
The retardation value Ro defined by the following formula (i) is within the range of 0 to 10 nm, the retardation value Rt defined by the following formula (ii) is within the range of −10 to 10 nm,
And the film thickness exists in the range of 5.0-15.0 micrometers, The polarizing plate protective film characterized by the above-mentioned.

[In formula, R represents a C1-C3 linear or branched alkyl group. ]
Formula (i)
_{Ro = (n x -n y)} × d
Formula (ii)
Rt = {(n _x + n _y ) / 2−n _z } × d
Wherein, Ro-plane direction of the retardation value of the film, Rt is the thickness direction of the retardation value of the film, n _x is a refractive index in a slow axis direction in the film plane, n _y is in the film plane The refractive index in the fast axis direction, _nz is the refractive index in the thickness direction of the film (the refractive index is measured at a wavelength of 590 nm in an environment of 23 ° C. and 55% RH), and d is the thickness (nm) of the film. . ]   2. The polarizing plate protective film according to claim 1, wherein the content of the matting agent is within a range of 0.1 to 0.5 mass% of the total mass of the film.   The polarizing plate protective film according to claim 1, further comprising a polyester plasticizer. A polarizing plate having a first protective film T1 on the viewing side and a second protective film T2 on the other surface side with a polarizer in between,
At least one of protective film T1 and protective film T2 is a polarizing plate protective film as described in any one of Claim 1- Claim 3. The polarizing plate characterized by the above-mentioned.   The polarizing plate according to claim 4, wherein the protective film T <b> 1 or the protective film T <b> 2 contains an ultraviolet absorber.   The protective film T1 and the protective film T2 are both polarizing plate protective films according to any one of claims 1 to 3, and contain an ultraviolet absorber. Item 5. The polarizing plate according to item 4.

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