JP2008102475A - Polarizing plate and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polarizing plate small in the change of transmittance and polarization degree due to heat or humidity and high in durability and a liquid crystal display device free from causing remarkable color tone change and having high display grade and to provide the polarizing plate and the liquid crystal display device free from being affected by heat or humidity and causing problems such as light leakage, having high display grade and stably and optically compensating a liquid crystal cell. <P>SOLUTION: The polarizing plate is formed by laminating a first protective film, a polarizer and a second protective film in this order. The moisture permeability of the first protective film at 60°C and 95% relative humidity is ≤300 g/m<SP>2</SP>day and the second protective film is a cellulose acylate film. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a polarizing plate and a liquid crystal display device.

Liquid crystal display devices have low power consumption, and their use is expanding year by year as space-saving image display devices.
Conventionally, a large viewing angle dependency of an image has been a major drawback of a liquid crystal display device. However, in recent years, high viewing angle liquid crystal modes such as a VA mode and an IPS mode have been put into practical use. Demand for liquid crystal display devices is rapidly expanding even in markets where demand is high.
Along with this, higher performance has begun to be demanded for polarizing plates used in liquid crystal display devices. In particular, improvement of durability against temperature and humidity is a big problem for polarizing plates.
The polarizing plate is manufactured by adsorbing iodine to a hydrophilic polymer film such as a polyvinyl alcohol film, a partially formalized polyvinyl alcohol, or an ethylene / vinyl acetate copolymer partially saponified film and then stretching the film. Is common.
However, these polarizing plates have a problem that, when used for a long period of time, the transmittance of the entire screen in black display increases, the color changes, and a frame-like light leak occurs.
The increase in the transmittance and the light leakage of the frame shape are due to relaxation of the stretched hydrophilic polymer and decomposition of iodine, and it is known that the amount of moisture permeation from the outside through the protective film greatly affects. It has been.
In addition, as a polarizing plate protective film used on the liquid crystal cell side, a cellulose acylate film is generally used. However, there is a problem that a change in optical properties accompanying a change in humidity of the cellulose acylate film deteriorates display performance. there were.
On the other hand, Patent Document 1 below discloses a method for providing a polarizing plate with small changes in transmittance and polarization degree due to heat and humidity.
Patent Document 2 below discloses a method for producing a polarizing plate by laminating a protective film with low moisture permeability and a polarizer.
However, these methods are not always sufficient in improving the durability.

JP 2005-266222 A JP 2005-309394 A

The present invention aims to solve the above-described problems and achieve the following objects. That is, an object of the present invention is to provide a highly durable polarizing plate with small changes in transmittance and polarization degree due to heat and humidity.
It is another object of the present invention to provide a liquid crystal display device with high display quality without causing a noticeable color change.

  In order to solve the above-mentioned problems, the present inventors have made extensive studies and as a result, obtained the following findings. That is, in order to improve the durability of the polarizing plate at high temperature and high humidity and realize high display quality, the second protective film on the side facing the liquid crystal cell can function as a retardation film. This is a finding that a high display quality can be realized by using an acylate film and setting the moisture permeability of the first protective film installed on the opposite side through the polarizer to a predetermined value or less.

The present invention is based on the above findings by the present inventors, and means for solving the above problems are as follows. That is,
<1> A polarizing plate formed by laminating a first protective film, a polarizer, and a second protective film in this order, and the moisture permeability of the first protective film at 60 ° C. relative humidity of 95% is The polarizing plate is 300 g / m ² · day or less, and the second protective film is a cellulose acylate film.
<2> The polarizing plate according to <1>, wherein the first protective film has a moisture permeability of 50 g / m ² · day or less.
<3> The absolute value of the difference between the in-plane retardation (Re10) of the second protective film at 25 ° C. relative humidity of 10% and the in-plane retardation (Re80) of 25 ° C. relative humidity of 80% The polarizing plate according to any one of <1> to <2>, wherein a value Gr divided by in-plane retardation (Re60) at 60% is 0.06 or more.
<4> The polarizing plate according to any one of <1> to <3>, wherein the second protective film satisfies the following formulas (I) and (II).
2.30 ≦ SA + SB <2.80 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Formula (I)
0 ≦ SB ≦ 1.00 ···································· Formula
In the above formulas (I) and (II), SA and SB represent the substitution degree of the acyl group substituted with the hydroxyl group of cellulose, SA represents the substitution degree of the acetyl group, and SB has 3 to 4 carbon atoms. Represents the substitution degree of the acyl group.
<5> The second protective film is stretched, the retardation value Re in the in-plane direction defined by the following formula (III) is in the range of 20 to 70 nm, and is defined by the following formula (IV). The polarizing plate according to <1> to <4>, wherein the retardation value Rth in the thickness direction is in the range of 30 to 400 nm.
Re = (nx−ny) × d... Formula (III)
Rth = {(nx + ny) / 2−nz} × d... Formula (IV)
In the above formulas (III) and (IV), nx is the refractive index in the slow axis direction in the film plane, ny is the refractive index in the fast axis direction in the film plane, and nz is the film refractive index. It is the refractive index in the thickness direction, and d is the thickness of the film.
<6> The polarizing plate according to any one of <1> to <4>, wherein Re and Rth of the second protective film are cellulose acylate films satisfying the following formulas (V) and (VI): .
｜ Re | ≦ 10 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Formula (V)
｜ Rth | ≦ 25 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Formula (VI)
<7> The polarizing plate according to any one of <1> to <6>, wherein the first protective film is a cycloolefin-based resin film.
<8> The polarizing plate according to any one of <1> to <7>, wherein at least one of a layer having a hard coat property and an antireflection layer is provided on the first protective film.

<9> A liquid crystal display device comprising a liquid crystal cell and two polarizing plates disposed on both sides thereof, wherein at least one polarizing plate is the polarizing plate according to any one of <1> to <8> The liquid crystal display device is characterized in that the second protective film of the polarizing plate is bonded to the side facing the liquid crystal cell.
<10> The liquid crystal display device according to <9>, wherein the liquid crystal cell is at least one of a VA mode and an IPS mode.

According to the present invention, it is possible to provide a highly durable polarizing plate with small changes in transmittance and polarization degree due to heat and humidity.
In addition, according to the present invention, it is possible to provide a liquid crystal display device with high display quality without causing a noticeable color change.

Below, the polarizing plate and liquid crystal display device which concern on this invention are demonstrated in detail.
In the description of the present embodiment, a numerical range expressed using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.
In the description of the present embodiment, “45 °”, “parallel” or “orthogonal” means that the angle is within a range of strictly less than ± 5 °. The error from the exact angle is preferably less than 4 °, more preferably less than 3 °. Regarding the angle, “+” means the clockwise direction, and “−” means the counterclockwise direction. Further, the “slow axis” means a direction in which the refractive index is maximized. The “visible light region” means 380 to 780 nm. Further, the refractive index measurement wavelength is a value in the visible light region (λ = 550 nm) unless otherwise specified.

In the description of the present embodiment, the term “polarizing plate” is used to include both a long polarizing plate and a polarizing plate cut into a size incorporated in a liquid crystal device unless otherwise specified. Yes. The “cutting” here includes “punching” and “cutting out”.
In the description of the present embodiment, “polarizing film” and “polarizing plate” are distinguished from each other. However, “polarizing plate” is a laminate having a transparent protective film that protects the polarizing film on at least one side of “polarizing film”. It shall mean the body.

In the description of the present embodiment, the “molecular symmetry axis” refers to a symmetry axis when the molecule has a rotational symmetry axis, but strictly requires that the molecule is rotationally symmetric. is not.
In general, in a discotic liquid crystalline compound, the molecular symmetry axis coincides with an axis perpendicular to the disc surface passing through the center of the disc surface, and in a rod-like liquid crystalline compound, the molecular symmetry axis is the major axis of the molecule. Match.

In this specification, Re (λ) and Rth (λ) represent in-plane retardation and retardation in the thickness direction at the wavelength λ, respectively. Re (λ) is measured with KOBRA 21ADH or WR (manufactured by Oji Scientific Instruments Co., Ltd.) by making light having a wavelength of λ nm incident in the normal direction of the film.
When the film to be measured is represented by a uniaxial or biaxial refractive index ellipsoid, Rth (λ) is calculated by the following method.
Rth (λ) is the film surface when Re (λ) is used and the in-plane slow axis (determined by KOBRA 21ADH or WR) is the tilt axis (rotation axis) (if there is no slow axis) Measurement is performed at a total of 6 points by injecting light of wavelength λ nm from the inclined direction in steps of 10 degrees from the normal direction to 50 degrees on one side with respect to the film normal direction (with any rotation direction as the rotation axis). Then, KOBRA 21ADH or WR is calculated based on the measured retardation value, the assumed value of the average refractive index, and the input film thickness value.
In the above case, in the case of a film having a direction in which the retardation value is zero at a certain tilt angle with the in-plane slow axis from the normal direction as the rotation axis, retardation at a tilt angle larger than the tilt angle. The value is calculated by KOBRA 21ADH or WR after changing its sign to negative.
The retardation value is measured from two inclined directions with the slow axis as the tilt axis (rotation axis) (if there is no slow axis, the arbitrary direction in the film plane is the rotation axis). Rth can also be calculated from the following formula (A) and formula (B) based on the value, the assumed value of the average refractive index, and the input film thickness value.

・ ・ ・ ・ ・ ・ Formula (A)
Note that Re (θ) represents a retardation value in a direction inclined by an angle θ from the normal direction.
Further, nx in the formula (A) represents the refractive index in the slow axis direction in the plane, ny represents the refractive index in the direction orthogonal to nx in the plane, and nz represents the refraction in the direction orthogonal to nx and ny. Represents a rate.

Rth = ((nx + ny) / 2−nz) × d (Equation (B)
When the film to be measured is a film that cannot be expressed by a uniaxial or biaxial refractive index ellipsoid, that is, a film without a so-called optical axis, Rth (λ) is calculated by the following method.
Rth (λ) is from −50 degrees with respect to the film normal direction, with Re (λ) being the in-plane slow axis (determined by KOBRA 21ADH or WR) as the tilt axis (rotation axis). Measured at 11 points by making light of wavelength λ nm incident from each tilted direction in steps of 10 degrees up to +50 degrees, and based on the measured retardation value, the assumed average refractive index and the input film thickness value. KOBRA 21ADH or WR is calculated.
In the above measurement, as the assumed value of the average refractive index, values in the polymer handbook (John Wiley & Sons, Inc.) and catalogs of various optical films can be used. If the average refractive index is not known, it can be measured with an Abbe refractometer. The average refractive index values of main optical films are exemplified below: cellulose acylate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49), Polystyrene (1.59). The KOBRA 21ADH or WR calculates nx, ny, and nz by inputting the assumed value of the average refractive index and the film thickness. Nz = (nx−nz) / (nx−ny) is further calculated from the calculated nx, ny, and nz.

(Polarizer)
The polarizing plate of the present invention is formed by laminating at least a first protective film, a polarizer, and a second protective film in this order.

<Polarizer>
The polarizer is preferably composed of polyvinyl alcohol (PVA) and a dichroic molecule. However, as described in JP-A-11-248937, PVA and polyvinyl chloride are dehydrated and dechlorinated. A polyvinylene-based polarizer in which a polyene structure is generated and oriented may be used.

  PVA is a polymer material obtained by saponifying polyvinyl acetate, but may contain components copolymerizable with vinyl acetate such as unsaturated carboxylic acid, unsaturated sulfonic acid, olefins, and vinyl ethers. Further, modified PVA containing an acetoacetyl group, a sulfonic acid group, a carboxyl group, an oxyalkylene group, or the like may be used.

There is no restriction | limiting in particular as a saponification degree of PVA, According to the objective, it can select suitably, For example, 80-100 mol% is preferable from viewpoints of solubility etc., and 90-100 mol% is more preferable.
Moreover, there is no restriction | limiting in particular as a polymerization degree of PVA, According to the objective, it can select suitably, For example, 1,000-10,000 are preferable and 1,500-5,000 are more preferable.
The syndiotacticity of PVA is not particularly limited and can be appropriately selected according to the purpose. For example, as described in Japanese Patent No. 2978219, 55% or more is required to improve durability. However, as described in Japanese Patent No. 3317494, 45 to 52.5% can be preferably used. After PVA is formed into a film, it is preferable to introduce a dichroic molecule to constitute a polarizer.
As a method for producing a PVA film, a method of forming a film by casting a stock solution obtained by dissolving a PVA resin in water or an organic solvent is generally preferably used. The concentration of the polyvinyl alcohol-based resin in the stock solution is usually 5 to 20% by mass, and a PVA film having a thickness of 10 to 200 μm can be produced by forming this stock solution by casting.
The PVA film can be produced with reference to the production methods described in Japanese Patent No. 3342516, Japanese Patent Application Laid-Open No. 09-328593, Japanese Patent Application Laid-Open No. 2001-302817, and Japanese Patent Application Laid-Open No. 2002-144401.

There is no restriction | limiting in particular as a crystallinity degree of a PVA film, According to the objective, it can select suitably, For example, the average crystallinity degree (Xc) described in patent 3251073 gazette of 50-75 mass% In order to reduce in-plane hue variation, a PVA film having a crystallinity of 38% or less described in JP-A-2002-236214 may be used.
The birefringence (Δn) of the PVA film is preferably small, and a PVA film having a birefringence of 1.0 × 10 ⁻³ or less described in Japanese Patent No. 3342516 can be preferably used. However, as described in JP-A-2002-228835, in order to obtain a high degree of polarization while avoiding cutting during stretching of the PVA film, the birefringence of the PVA film may be set to 0.02 or more and 0.01 or less. Alternatively, as described in JP-A-2002-060505, the value of (nx + ny) / 2-nz may be set to 0.0003 or more and 0.01 or less.
The in-plane retardation Re of the PVA film is preferably 0 nm or more and 100 nm or less, and more preferably 0 nm or more and 50 nm or less.
The retardation Rth in the (film) thickness direction of the PVA film is preferably 0 nm or more and 500 nm or less, and more preferably 0 nm or more and 300 nm or less.
In addition, as a polarizing plate of the present invention, a PVA film having a 1,2-glycol bond amount of 1.5 mol% or less described in Japanese Patent No. 3021494, and Japanese Patent Application Laid-Open No. 2001-316492. A PVA film having 500 or less optical foreign matters of 5 μm or more per 100 cm ² , and a PVA film having a hot water cutting temperature spot of 1.5 ° C. or less in the TD direction of the film described in JP-A-2002-030163 Further, PVA formed from a solution in which 15 to 10% by mass of a plasticizer described in JP-A 06-289225 is mixed with 1 to 100 parts by mass of a trivalent or hexavalent polyhydric alcohol such as glycerin. A film is preferably used.

The film thickness before stretching of the PVA film is not particularly limited and can be appropriately selected depending on the purpose. For example, from the viewpoint of film holding stability and stretching uniformity, 1 μm to 1 mm is preferable. 20-200 micrometers is more preferable. Further, as described in JP-A-2002-236212, a thin PVA film may be used in which the stress generated when stretching 4 to 6 times in water is 10 N or less.
Dichroic molecule I ₃ ^- or I ₅ ^- higher iodine ion such as, or a dichroic dye is preferably used. Among them, higher-order iodine ions are particularly preferably used in the present invention. Higher-order iodine ions were obtained by dissolving iodine in an aqueous potassium iodide solution as described in “Application of Polarizing Plate” by Nagata Ryo, CMC Publishing and Industrial Materials, Vol. 28, No. 7, p39-p45. PVA can be immersed in a liquid and / or boric acid aqueous solution, and can be produced in a state of being adsorbed and oriented in PVA.
When a dichroic dye is used as the dichroic molecule, an azo dye is preferable, and among them, a bisazo dye and a trisazo dye are more preferable. The dichroic dye is preferably a water-soluble dye. For this reason, a hydrophilic substituent such as a sulfonic acid group, an amino group or a hydroxyl group is introduced into the dichroic molecule, so that a free acid, an alkali metal salt, an ammonium salt or an amine is introduced. It is preferably used as a salt.

Specific examples of such dichroic dyes include C.I. I. DirectRed37, CongoRed (C.I.DirectRed28), C.I. I. DirectViolet 12, C.I. I. DirectBlue90, C.I. I. DirectBlue 22, C.I. I. DirectBlue1, C.I. I. DirectBlue 151, C.I. I. Benzidines such as DirectGreen 1, C.I. I. Direct Yellow 44, C.I. I. DirectRed 23, C.I. I. Diphenylurea series such as DirectRed 79, C.I. I. Stilbene series such as Direct Yellow 12, C.I. I. Dinaphthylamine type such as DirectRed 31, C.I. I. DirectRed 81, C.I. I. DirectViolet 9, C.I. I. Examples include J acid systems such as DirectBlue 78.
In addition, C.I. I. Direct Yellow 8, C.I. I. Direct Yellow 28, C.I. I. Direct Yellow 86, C.I. I. Direct Yellow 87, C.I. I. Direct Yellow 142, C.I. I. Direct Orange 26, C.I. I. Direct Orange 39, C.I. I. Direct Orange 72, C.I. I. Direct Orange 106, C.I. I. Direct Orange 107, C.I. I. DirectRed2, C.I. I. DirectRed 39, C.I. I. DirectRed 83, C.I. I. DirectRed 89, C.I. I. DirectRed 240, C.I. I. DirectRed 242, C.I. I. DirectRed 247, C.I. I. DirectViolet 48, C.I. I. DirectViolet 51, C.I. I. DirectViolet 98, C.I. I. DirectBlue 15, C.I. I. DirectBlue 67, C.I. I. DirectBlue 71, C.I. I. DirectBlue 98, C.I. I. DirectBlue 168, C.I. I. DirectBlue 202, C.I. I. DirectBlue 236, C.I. I. DirectBlue 249, C.I. I. DirectBlue 270, C.I. I. DirectGreen 59, C.I. I. DirectGreen 85, C.I. I. Direct Brown 44, C.I. I. Direct Brown 106, C.I. I. Direct Brown 195, C.I. I. Direct Brown 210, C.I. I. Direct Brown 223, C.I. I. Direct Brown 224, C.I. I. DirectBlack1, C.I. I. DirectBlack17, C.I. I. DirectBlack 19, C.I. I. Direct Black 54 and the like are further disclosed in JP-A-62-70802, JP-A-1-161202, JP-A-1-172906, JP-A-1-172907, JP-A-1-183602, JP-A-1-183602. The dichroic dyes described in Japanese Patent No. 248105, Japanese Patent Application Laid-Open No. 1-265205, and Japanese Patent Application Laid-Open No. 7-261024 are preferably used. In order to produce dichroic molecules having various hues, two or more of these dichroic dyes may be blended. When a dichroic dye is used, the adsorption thickness may be 4 μm or more as described in JP-A-2002-082222.

If the content of the dichroic molecule in the film is too small, the degree of polarization is low, and if it is too large, the single-plate transmittance is lowered. Therefore, the polyvinyl alcohol polymer constituting the film matrix is usually used. On the other hand, it is adjusted to a range of 0.01% by mass to 5% by mass.
As a preferable film thickness of the polarizer, 5 to 40 μm is preferable, and 10 to 30 μm is more preferable. Further, as described in JP-A-2002-174727, the ratio between the thickness of the polarizer and the thickness of the protective film described later is 0.01 ≦ A (polarizer film thickness) / B (protective film thickness). ) ≦ 0.8 is also preferable.

<First protective film>
The first protective film has a moisture permeability of 300 g / m ² · day or less at 60 ° C. and a relative humidity of 95%, more preferably 50 g / m ² · day or less. More preferably, it is 10 g / m ² · day or less.
The first protective film is not particularly limited as long as it satisfies the above moisture permeability conditions and the transmittance is 80% or more, and can be appropriately selected according to the purpose. For example, cycloolefin resin, polyester A transparent film in which a coating layer having low moisture permeability is provided on at least one surface of a transparent substrate film made of a resin, a polycarbonate resin, or cellulose acylates is preferably used. Among these, a cycloolefin resin film is particularly preferable from the viewpoint of moisture permeability.

<< Moisture permeability >>
Here, the measurement method of moisture permeability is “Polymer Physical Properties II” (Polymer Experiment Course 4, Kyoritsu Shuppan), pages 285-294: Measurement of vapor permeation (mass method, thermometer method, vapor pressure method, adsorption) However, in the present invention, the moisture permeability was calculated according to JIS Z-0208, except that the humidity control condition was changed to 60 ° C. and 95% RH. At this time, the operation of taking out and weighing the cup placed in the thermo-hygrostat at an appropriate time interval is repeated, and the increase in mass per unit time is obtained with two successive weighings, and it becomes constant within 5%. The evaluation continued until.
Moreover, in order to exclude the influence by the moisture absorption etc. of a sample, the blank cup which does not put a hygroscopic agent was measured, and the value of moisture permeability was correct | amended.
When measuring the moisture permeability of a polarizing plate protective film having a resin layer containing a vinyl alcohol polymer, set the sample in such a direction that the resin layer provided on the transparent substrate film contacts the measuring cup, The moisture permeability from the transparent base film side was measured by the same method as described above.

<< Coating layer >>
There is no restriction | limiting in particular as a coating layer on the said cellulose acylate base material, According to the objective, it can select suitably, For example, the coating which has a polymer containing the repeating unit induced | guided | derived from a chlorine containing vinyl monomer It contains at least one of a layer, a coating layer made of a vinyl alcohol polymer, a compound made of alkoxysilane, a compound having a functional group that reacts with a hydroxyl group or an alkoxyl group, and a silane coupling agent. Coating layer, coating layer mainly composed of silica formed from a coating composition containing polysilazane, coating layer containing a hydrophobic compound, coating formed by laminating a resin composition comprising a saccharide and a formyl group-containing compound A resin composition comprising a layer, an amino group-containing polymer compound and an aminosilane-reactive functional group-containing silanol group-containing organosilane compound Layers were formed by coating, and the coating layer is preferably used for the particle radius is contained 0.1~10μm of the inorganic layered compound. Among these, a coating layer having a polymer containing a repeating unit derived from a chlorine-containing vinyl monomer, and a coating layer made of a vinyl alcohol polymer are more preferably used.

[Chlorine-containing vinyl monomer]
In general, examples of the chlorine-containing vinyl monomer include vinyl chloride and vinylidene chloride. A chlorine-containing polymer can be obtained by copolymerizing these vinyl chloride or vinylidene chloride monomers with a monomer copolymerizable therewith.

[Monomer copolymerizable with chlorine-containing vinyl monomer]
Monomers copolymerizable with chlorine-containing vinyl monomers include olefins, styrenes, acrylic acid esters, methacrylic acid esters, acrylamides, methacrylamides, itaconic acid diesters, maleic acid esters, Selected from fumaric acid diesters, N-alkylmaleimides, maleic anhydride, acrylonitrile, vinyl ethers, vinyl esters, vinyl ketones, vinyl heterocycles, glycidyl esters, unsaturated nitriles, unsaturated carboxylic acids, etc. Monomer.

Examples of olefins include dicyclopentadiene, ethylene, propylene, 1-butene, 1-pentene, isoprene, chloroprene, butadiene, 2,3-dimethylbutadiene and the like.
Examples of styrenes include styrene, methyl styrene, dimethyl styrene, trimethyl styrene, ethyl styrene, isopropyl styrene, chloromethyl styrene, methoxy styrene, acetoxy styrene, chloro styrene, dichloro styrene, bromo styrene, trifluoromethyl styrene, vinyl. And benzoic acid methyl ester.

  Specific examples of acrylic esters and methacrylic esters include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, amyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, t-octyl acrylate, 2-methoxyethyl acrylate, 2- Butoxyethyl acrylate, 2-phenoxyethyl acrylate, chloroethyl acrylate, cyanoethyl acrylate, dimethylaminoethyl acrylate, benzyl acrylate, methoxybenzyl acrylate, furfuryl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, butyl methacrylate , Amyl methacrylate, Xyl methacrylate, 2-ethylhexyl methacrylate, octyl methacrylate, benzyl methacrylate, cyanoacetoxyethyl methacrylate, chlorobenzyl methacrylate, sulfopropyl methacrylate, N-ethyl-N-phenylaminoethyl methacrylate, 2-methoxyethyl methacrylate, 2- (3-phenylpropiyl) Ruoxy) ethyl methacrylate, dimethylaminophenoxyethyl methacrylate, furfuryl methacrylate, tetrahydrofurfuryl methacrylate, phenyl methacrylate, cresyl methacrylate, naphthyl methacrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, 3-chloro 2-hydroxypropyl methacrylate, 3-chloro-2-hydroxypropyl methacrylate, 2,2-dimethylhydroxypropyl acrylate, 5-hydroxypentyl acrylate, diethylene glycol monoacrylate, trimethylolpropane monoacrylate, pentaerythritol monoacrylate, 2,2- Examples include dimethyl-3-hydroxypropyl methacrylate, 5-hydroxypropyl methacrylate, diethylene glycol monomethacrylate, trimethylolpropane monomethacrylate, and pentaerythritol monomethacrylate.

  Specific examples of vinyl ethers include methyl vinyl ether, butyl vinyl ether, hexyl vinyl ether, octyl vinyl ether, decyl vinyl ether, ethyl hexyl vinyl ether, methoxyethyl vinyl ether, ethoxyethyl vinyl ether, chloroethyl vinyl ether, 1-methyl-2,2-dimethylpropyl. Vinyl ether, 2-ethylbutyl ether, dimethylaminoethyl vinyl ether, diethylaminoethyl vinyl ether, butylaminoethyl vinyl ether, benzyl vinyl ether, tetrahydrofurfuryl vinyl ether, vinyl phenyl ether, vinyl tolyl ether, vinyl chlorophenyl ether, vinyl-2,4-dichloro Phenyl ether, vinyl naphthyl ether, vinyl Such as cement Lani ether, and the like.

  Specific examples of vinyl esters include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl dimethyl propionate, vinyl ethyl butyrate, vinyl valerate, vinyl caproate, vinyl chloro. Acetate, vinyl dichloroacetate, vinyl methoxyacetate, vinyl butoxy acetoacetate, vinyl phenyl acetate, vinyl acetoacetate, vinyl lactate, vinyl-β-phenylbutyrate, vinyl cyclohexyl carboxylate, vinyl benzoate, vinyl salicylate, chlorobenzoic acid Examples include vinyl, vinyl tetrachlorobenzoate, vinyl naphthoate, and the like.

  Acrylamides include acrylamide, methylacrylamide, ethylacrylamide, propylacrylamide, butylacrylamide, t-butylacrylamide, cyclohexylacrylamide, benzylacrylamide, hydroxymethylacrylamide, methoxyethylacrylamide, dimethylaminoethylacrylamide, phenylacrylamide, dimethylacrylamide, and diethyl. Examples include acrylamide, β-cyanoethyl acrylamide, and N- (2-acetoacetoxyethyl) acrylamide.

  Examples of methacrylamides include methacrylamide, methyl methacrylamide, ethyl methacrylamide, propyl methacrylamide, butyl methacrylamide, tert-butyl methacrylamide, cyclohexyl methacrylamide, benzyl methacrylamide, hydroxymethyl methacrylamide, methoxyethyl methacrylamide , Dimethylaminoethylmethacrylamide, phenylmethacrylamide, dimethylmethacrylamide, diethylmethacrylamide, β-cyanoethylmethacrylamide, N- (2-acetoacetoxyethyl) methacrylamide and the like.

  Further, acrylamides having a hydroxyl group can be used, and examples thereof include N-hydroxymethyl-N- (1,1-dimethyl-3-oxo-butyl) acrylamide, N-methylol acrylamide, N-methylol methacryl. Examples include amide, N-ethyl-N-methylol acrylamide, N, N-dimethylol acrylamide, N-ethanol acrylamide, N-propanol acrylamide, N-methylol acrylamide and the like.

  Examples of the itaconic acid diesters include dimethyl itaconate, diethyl itaconate, and dibutyl itaconate. Examples of maleic acid diesters include diethyl maleate, dimethyl maleate, and dibutyl maleate. Examples of the fumaric acid diesters include diethyl fumarate, dimethyl fumarate, dibutyl fumarate and the like.

  Examples of vinyl ketones include methyl vinyl ketone, phenyl vinyl ketone, methoxyethyl vinyl ketone, and the like. Examples of the vinyl heterocyclic compound include vinyl pyridine, N-vinyl imidazole, N-vinyl oxazolidone, N-vinyl triazole, and N-vinyl pyrrolidone. Examples of glycidyl esters include glycidyl acrylate and glycidyl methacrylate. Examples of unsaturated nitriles include acrylonitrile and methacrylonitrile. Examples of N-alkylmaleimides include N-ethylmaleimide and N-butylmaleimide.

  Examples of the unsaturated carboxylic acids include acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid and the like, and further anhydrides such as fumaric acid, itaconic acid and maleic acid. Two or more of these copolymerizable monomers may be used.

  Examples of the chlorine-containing polymer in the present invention include JP-A-53-58553, JP-A-55-43185, JP-A-57-139109, JP-A-57-139136, JP-A-60. -235818, JP-A 61-108650, JP-A 62-256871, JP-A 62-280207, JP-A 63-256665, and the like.

  The proportion of the chlorine-containing vinyl monomer in the chlorine-containing polymer is preferably from 50 to 99 mass%, more preferably from 60 to 98 mass%, still more preferably from 70 to 97 mass%. If the ratio of the chlorine-containing vinyl monomer is 50% or more, problems such as deterioration in moisture permeability do not occur, and if it is 99% or less, solubility in various solvents is obtained, which is preferable.

  Chlorine-containing polymers are available from Asahi Kasei Chemicals Corporation and Kureha Chemical Corporation. The products available from Asahi Kasei Chemicals Corporation include “Saran Resin R241C”, “Saran Resin F216”, “Saran Resin R204”, “Saran Latex L502”, “Saran Latex L529B”, “Saran Latex L536B”, “Saran Latex L544D”. ”,“ Saran Latex L549B ”,“ Saran Latex L551B ”,“ Saran Latex L557 ”,“ Saran Latex L561A ”,“ Saran Latex L116A ”,“ Saran Latex L411A ”,“ Saran Latex L120 ”,“ Saran Latex L123D ”, “Saran Latex L106C”, “Saran Latex L131A”, “Saran Latex L111”, “Saran Latex L232A”, and “Saran Latex L321B” And the like.

Since the coating layer is often wet coated, the solvent used in the coating composition is an important factor. Requirements include sufficiently dissolving the above solute and being less likely to cause coating unevenness and drying unevenness during the coating to drying process. In addition, the solubility of the transparent base film is not too high (necessary for preventing failure such as deterioration of flatness and whitening), and conversely, the support is dissolved and swollen to the minimum extent (necessary for adhesion) , Etc. are also preferred properties.
One type of solvent may be used, but it is particularly preferable to adjust the solubility of the support, the swelling property, the solubility of the material, the drying property, the aggregation property of the particles, and the like by using two or more types of solvents. By adding a small amount of highly swellable solvent to the low-swelling main solvent of the transparent support, adhesion to the transparent support (transparent substrate film) without deteriorating other performance and surface conditions Can be improved.
The coating solution may contain an organic solvent such as a ketone, alcohol, ester or ether. Preferred organic solvents are tetrahydrofuran, ketones (methyl ethyl ketone, acetone, methyl isobutyl ketone, cyclohexanone, etc.), ethyl acetate, and butyl acetate. BTXs such as toluene are also preferably used.
In the present invention, when the chlorine-containing polymer is vinylidene chloride, it is preferable to use tetrahydrofuran as the main solvent. It is more preferable to use a copolymer of vinylidene chloride so that it can be dissolved in toluene, a ketone solvent, etc., and toluene, a ketone solvent, etc. are used without using tetrahydrofuran. Further, it is also preferable to add the above solvent within a range where the solute dissolves in tetrahydrofuran. When the chlorine-containing polymer is supplied as a latex dispersion, water is preferably used as the main solvent. In the case of a latex dispersion, it is preferable to use a surfactant, a thickener or the like in combination.

When coating a coating layer containing a chlorine-containing polymer on a transparent substrate film, Silicia (made by Fuji Silysia), Mizuka Seal (made by Mizusawa Chemical Co., Ltd.), NipSeal (made by Nippon Silica Industry Co., Ltd.) is used to improve blocking resistance. 0.2 to 1.0 part of silica powder such as) or the like, paraffin wax (manufactured by Nippon Seiwa), behenic acid (manufactured by NOF), stearic acid (manufactured by NOF) It is also preferable to add 0.2 to 5.0 parts of a wax emulsion such as Further, modified waxes are preferably used as described in paragraphs [0012] to [0016] of JP-A-9-143419.
Since the chlorine-containing polymer is decomposed and colored by heat, light, and ultraviolet rays, it is preferable that stearic acid such as lead, zinc, barium, silver salts, magnesium oxide, or the like is used together as a stabilizer. Moreover, you may use antioxidants as described in Paragraph [0013]-[0020] of Unexamined-Japanese-Patent No. 2004-359819.
Furthermore, in order to increase the adhesion between the coating layer containing the chlorine-containing polymer and the transparent substrate film, and other layers, isocyanates such as Coronate L (made by Nippon Polyurethane) and Takenate A-3 (Takeda Pharmaceutical). It is also preferable to add 0.1 to 1.0 part of an adhesive with respect to the chlorine-containing polymer.

  The coating method is not particularly limited, but dip coating method, air knife coating method, curtain coating method, roller coating method, wire bar coating method, gravure coating method and extrusion coating method (die coating method) (see US Pat. No. 2,681,294) ), A known method such as a micro gravure coating method is used, and among them, the micro gravure coating method and the die coating method are preferably used from the viewpoint of high productivity and coating film uniformity.

  Drying is preferably performed under conditions where the concentration of the organic solvent in the applied liquid film is 5% by mass or less after drying, more preferably 2% by mass or less, and even more preferably 1% by mass or less. Although the drying conditions are affected by the thermal strength and transport speed of the transparent substrate film, the length of the drying process, etc., it is preferable that the organic solvent content is as low as possible in terms of film hardness and adhesion prevention. When an organic solvent is not contained, the drying step can be omitted and ultraviolet irradiation can be performed immediately after coating.

1-10 micrometers is preferable, as for the thickness of a coating layer, 2-9 micrometers is more preferable, and 3-8 micrometers is still more preferable. When the thickness is 1 μm or less, the moisture-proof property is inferior, and when the thickness is 10 μm or more, it is not suitable as a polarizing plate protective film because it becomes a brittle film or is easily colored.
Further, the haze of the coating layer is preferably 5% or less, more preferably 3% or less, and still more preferably 1% or less. The ratio between the surface haze and the internal haze is not particularly limited and can be appropriately selected according to the purpose. The surface haze is preferably 1% or less.

[Coating layer made of vinyl alcohol polymer]
Examples of the vinyl alcohol polymer constituting the coating layer include a homopolymer such as polyvinyl alcohol (PVA), an ethylene-vinyl alcohol copolymer (EVOH), and the like.
In addition, these vinyl alcohol polymers may be partially carbonyl-modified, silanol-modified, epoxy-modified, acetoacetyl-modified, amino-modified or ammonium-modified, and a part thereof is a diacetone acrylamide unit. You may use the copolymer containing etc.
Various vinyl alcohol polymers can be used alone or in combination of two or more.

  The saponification degree of the vinyl alcohol polymer can be selected from a range of 80 mol% or more, but is preferably 96 mol% or more, and more preferably 99 mol% or more. The degree of polymerization of the vinyl alcohol polymer is preferably 200 to 5,000, more preferably 400 to 5,000, and still more preferably about 500 to 3,000, from the viewpoint of moisture permeability and coatability.

In order to further reduce the moisture permeability of the vinyl alcohol-based coating layer, it is more preferable to disperse the inorganic layered compound.
The inorganic layered compound in the present invention is an inorganic compound having a structure in which unit crystal layers are laminated and exhibiting a property of swelling or cleaving by coordinating or absorbing a solvent between the layers.
Examples of such inorganic compounds include swellable hydrous silicates such as smectite group clay minerals (montmorillonite, saponite, hectorite, etc.), palm curite group clay minerals, kaolinite group clay minerals, phyllosilicates (mica). Etc.).
In addition, a synthetic inorganic layered compound is also preferably used. Examples of the synthetic inorganic layered compound include synthetic smectite (hectorite, saponite, stevensite, etc.), synthetic mica, etc., preferably smectite, montmorillonite, mica, montmorillonite, mica. Is more preferable, and mica is more preferable. Among these, synthetic mica is particularly preferable from the viewpoint of moisture permeability reduction and tinting suppression. Such inorganic layered compounds may be those obtained by subjecting these inorganic layered compounds to an organic treatment.

The swellable layered inorganic compound is preferably finely divided from the viewpoint of achieving both gas barrier properties and adhesion between the substrate and the gas barrier layer.
The swellable layered inorganic compound that has been microparticulated is usually plate-shaped or flat-shaped, and the planar shape is not particularly limited, and may be an amorphous shape.
The average particle diameter (planar average particle diameter) of the swellable layered inorganic compound that has been microparticulated is preferably, for example, 0.1 to 10 μm, more preferably 0.5 to 8 μm, and even more preferably 0.8 to 6 μm. preferable. If the particle diameter is smaller than this range, the effect of reducing moisture permeability is not sufficient, and if the particle diameter is large, an increase in haze value, an increase in surface roughness, and the like are not preferable.
3-60 mass% is preferable, as for the density | concentration of an inorganic compound, 3-50 mass% is more preferable, and 3-40 mass% is still more preferable. If the concentration of the inorganic compound is less than 3% by mass, the effect of reducing moisture permeability is not sufficient, and if the concentration of the inorganic compound is more than 60% by mass, an increase in haze value and deterioration of brittleness are not preferable.

In the present invention, as a component of the resin composition, a vinyl alcohol polymer crosslinking agent can be further added to the vinyl alcohol polymer and the layered inorganic compound, thereby improving the water resistance of the adhesive layer. it can.
The crosslinking agent is not particularly limited and may be appropriately selected depending on the intended purpose.For example, phenol resin, melamine resin, urea resin, polyamide polyurea, dimethylol urea, dimethylol melamine, polyvalent epoxy compound, divalent epoxy compound, Aldehyde compounds, polyvalent isocyanate resins, aziridine compounds, polyamidoamine epichlorohydrin compounds, activated vinyl compounds, dicarbonate compounds, hydrazino group-containing compounds (other-valent carboxylic acid polyhydrazide compounds), colloidal silica, zirconium salts, polyvalent metal salts, Examples include boric acid, phosphoric acid, polyacrylic acid, dicarboxylic acid, adipic acid anhydride, succinic acid anhydride, titanium compounds such as tetraisopropyl titanate, diisopropoxybis (acetylacetone) titanate, and others. Coupling agents such as propyl trimethoxysilane, the use of such radical generator such as peroxide is also possible. It is also possible to add a catalyst and other additives for promoting the crosslinking reaction.

The addition amount of the crosslinking agent is preferably 0.5% by mass or more, more preferably 1% by mass or more, and particularly preferably 2% by mass or more in terms of (crosslinking agent / (vinyl alcohol polymer + crosslinking agent)). . In the case where the mass ratio of the crosslinking agent to both the PVA polymer and the crosslinking agent is less than 0.5% by mass, the effect is not exhibited by adding the crosslinking agent.
The mass ratio of the crosslinking agent to both the vinyl alcohol polymer and the crosslinking agent is preferably 50% by mass or less, more preferably 40% by mass or less, and still more preferably 30% by mass or less. Since some crosslinking agents such as aldehyde-based compounds turn yellow by heat, it is necessary to reduce the amount of such crosslinking agents to be within an allowable range by reducing the amount of addition.

Formation of a coating layer composed of a vinyl alcohol polymer or a vinyl alcohol polymer and an inorganic layered compound is formed by a dip coating method, an air knife coating method, a curtain coating method, a roller coating method, a wire bar coating method, or a gravure coating method. And known methods such as an extrusion coating method (die coating method) (see US Pat. No. 2,681,294) and a micro gravure coating method. Among them, the micro gravure coating method and the die coating method have high productivity and uniform coating. It is preferably used from the viewpoint of sex. At this time, in order to optimize the viscosity characteristic of the liquid for the coating apparatus during film formation, a method of adjusting the liquid viscosity of the coating liquid by adding a viscosity modifier such as a thickener to the coating liquid is also used. You can also.
In order to further improve the moisture resistance and water resistance of the coating layer, it is preferable to heat-treat the resin layer at 90 ° C. or higher and 150 ° C. or lower for several minutes after applying the coating layer on the cellulose acylate substrate. It is preferable to heat at 130 ° C. or higher and 150 ° C. or lower. The heat treatment time is preferably from 1 minute to 20 minutes, more preferably from 5 minutes to 15 minutes, from the viewpoint of productivity and water resistance. Moreover, it is preferable that the cellulose acylate is previously saponified from the viewpoint of adhesion between the resin layer and the cellulose acylate substrate.

  1-10 micrometers is preferable, as for the thickness of a coating layer, 2-9 micrometers is more preferable, and 3-8 micrometers is still more preferable.

<< Polyester resin >>
There is no restriction | limiting in particular as polyester-type resin, According to the objective, it can select suitably, For example, a polyethylene terephthalate, a polyethylene naphthalate, a polybutylene terephthalate, a polybutylene naphthalate etc. are mentioned. Among these, it is particularly preferable to use polyethylene terephthalate from the viewpoint of cost and mechanical strength. Particularly preferred among these is a resin obtained by condensation polymerization using an aromatic dicarboxylic acid and an aliphatic glycol.

  Aromatic dicarboxylic acids include terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, etc., and use these lower alkyl esters (derivatives capable of forming esters such as anhydrides and lower alkyl esters). Can do.

Examples of the aliphatic glycol include ethylene glycol, propylene glycol, butanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, diethylene glycol, and p-xylylene glycol.
Of these, polyethylene terephthalate obtained by the reaction of terephthalic acid and ethylene glycol is preferred as the main component.

  The main component being polyethylene terephthalate means that it contains 80% by mass or more of a polyethylene terephthalate copolymer or a copolymer having 80% by mol or more of repeating units of polyethylene terephthalate.

  The polyester used for the protective film may be further copolymerized with other components or may be blended with other polymers as long as the effects of the present invention are not impaired.

  The polyester may be one in which at least one of a terminal hydroxyl group and a carboxyl group is blocked with a monofunctional compound such as benzoic acid, benzoylbenzoic acid, benzyloxybenzoic acid, and methoxypolyalkylene glycol, or For example, it may be modified with a very small amount of trifunctional or tetrafunctional ester-forming compound such as glycerin and pentaerythritol within a range in which a substantially linear copolymer is obtained.

Moreover, the polyester used for this invention can be copolymerized with the compound which has a bisphenol type compound, a naphthalene ring, or a cyclohexane ring for the purpose of improving the heat resistance of a film.
The polyester used in the present invention preferably has a glass transition temperature (Tg) of 80 ° C. or higher, more preferably 90 ° C. or higher. If it is less than 80 degreeC, the dimensional stability of the obtained film under high temperature and high humidity may be inferior. Tg was determined from the tan δ peak measured by dynamic viscoelasticity.

  The polyester used in the present invention may contain an antioxidant. The effect is particularly remarkable when the polyester contains a compound having a polyoxyalkylene group. There are no particular limitations on the type of antioxidant to be contained, and various types of antioxidants can be used. Examples thereof include antioxidants such as hindered phenol compounds, phosphite compounds, and thioether compounds. It is done. Among these, an antioxidant of a hindered phenol compound is preferable in terms of transparency. Content of antioxidant is 0.01-2 mass% normally with respect to polyester, Preferably it is 0.1-0.5 mass%.

  If necessary, the polyester film may be provided with easy slipperiness. The slipperiness imparting means is not particularly limited, but the external particle addition method for adding inert inorganic particles to the polyester, the internal particle precipitation method for precipitating the catalyst to be added at the time of polyester synthesis, or a surfactant, etc. A method of applying to the surface is common.

  If necessary, an ultraviolet absorber may be added to the polyester film to prevent deterioration of the polarizer and the liquid crystal.

  From the viewpoint of excellent ultraviolet ray absorption and good liquid crystal display properties, the ultraviolet absorber preferably has a transmittance of 0 to 50% at a wavelength of 380 nm of the polyester film added with the ultraviolet absorber. More preferably, it is -30%, and it is still more preferable that it is 0-10%. Further, the transmittance at 600 nm is preferably 80 to 100%, more preferably 85 to 100%, and still more preferably 90 to 100%.

  The polyester film is preferably a polyester film formed by biaxial stretching. The polyester film can be obtained by a conventionally known method, and is not particularly limited, but can be carried out by the following method. In this case, the longitudinal direction refers to the film forming direction (longitudinal direction) of the film, and the horizontal direction refers to a direction perpendicular to the film forming direction of the film.

  First, the raw material polyester is molded into pellets, dried with hot air or vacuum, melt-extruded, extruded into a sheet from a T-die, brought into close contact with a cooling drum by an electrostatic application method, etc., cooled and solidified, and unstretched Get a sheet. Subsequently, the obtained unstretched sheet is heated within a range of glass transition temperature (Tg) ° C. to (Tg + 100) ° C. of polyester through at least one of a plurality of roll groups and a heating device such as an infrared heater. Or it is the method of carrying out multistage longitudinal stretch.

  Next, the polyester film stretched in the longitudinal direction obtained as described above is transversely stretched and then heat-set within a temperature range of Tg to Tm (melting point).

  The heat-set film is usually cooled to Tg or less, and the clip gripping portions at both ends of the film are cut and wound. Under the present circumstances, it is preferable to perform a 0.1-10% relaxation process to at least any one of a horizontal direction and a vertical direction within the temperature range below the last heat setting temperature and Tg. The means for cooling and relaxation treatment is not particularly limited and can be performed by a conventionally known means. However, it is preferable to perform these treatments while sequentially cooling in a plurality of temperature ranges, from the viewpoint of improving the dimensional stability of the film.

  More optimal conditions of these heat setting conditions, cooling, and relaxation treatment conditions vary depending on the polyester constituting the film, so if the physical properties of the obtained stretched film are measured and appropriately adjusted to have favorable characteristics, Good.

  In the production of the film, a functional layer such as an antistatic layer, a slippery layer, an adhesive layer, or a barrier layer may be coated at least one of before and after stretching. At this time, various surface treatments such as corona discharge treatment, atmospheric pressure plasma treatment, and chemical treatment can be performed as necessary.

  The clip gripping portions at both ends of the cut film are pulverized, or after granulation, depolymerization / repolymerization, etc., if necessary, as a film raw material of the same variety or of different varieties. You may reuse as a raw material for films.

  The thickness of the polyester film is preferably 5 to 200 μm, more preferably 5 to 100 μm, and still more preferably 40 to 100 μm.

[Adhesion with polarizer]
The adhesive surface between the polyester resin and the polarizer may be subjected to a treatment for improving the adhesive force as necessary. Typical examples of such treatment include dry treatment and easy adhesion treatment.
Specific examples of the dry treatment include corona treatment, gas corona treatment, plasma treatment, and low-pressure UV treatment. As a specific example of the easy adhesion treatment, coating of an easy adhesion treatment material can be given.
Examples of the easy adhesion treatment material include cellulose resin, urethane resin, silane coupling agent, silicon primer, PVA, nylon, styrene resin, and the like. Dry treatment and easy adhesion treatment can be used in combination. Alternatively, the adhesive strength can be improved by performing a saponification treatment with an aqueous sodium hydroxide solution. The saponification treatment can be used in combination with the easy adhesion treatment.

<< Polycarbonate resin >>
The polycarbonate resin used in the present invention is a polyester of carbonic acid and glycol or dihydric phenol, and carbonic acid and 2,2′-bis (4-hydroxyphenyl) -propane (commonly called bisphenol-A) are structural units. Of course, the present invention is not limited to this. For example, 1,1-bis (4-hydroxyphenyl) -alkylcycloalkane, 1,1-bis (3-substituted-4) -Hydroxyphenyl) -alkylcycloalkanes, 1,1-bis (3,5-substituted-4-hydroxyphenyl) -alkylcycloalkanes, 9,9-bis (4-hydroxyphenyl) fluorenes A homo- or copolymer polycarbonate comprising at least one dihydric phenol as a monomer component, 2 above Examples thereof include a mixture of a polyhydric phenol and a polycarbonate containing bisphenol A as a monomer component, and a copolymer polycarbonate containing the above dihydric phenol and bisphenol A as monomer components.

  Specific examples of 1,1-bis (4-hydroxyphenyl) -alkylcycloalkane include 1-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane, 1,1-bis (4-hydroxyphenyl) ) -3,3-dimethyl-5,5-dimethylcyclohexane, 1,1-bis (4-hydroxyphenyl) -3,3-dimethyl-5-methylcyclopentane and the like.

  1,1-bis (3-substituted-4-hydroxyphenyl) -alkylcycloalkane includes 1,1-bis (4-hydroxyphenyl) -alkyl substituted with an alkyl group having 1 to 12 carbon atoms or a halogen group. Cycloalkanes such as 1,1-bis (3-methyl-4-hydroxyphenyl) -3,3,5-trimethylcyclohexane, 1,1-bis (3-ethyl-4-hydroxyphenyl) -3,3- Dimethyl-5,5-dimethylcyclohexane, 1,1-bis (3-chloro-4-hydroxyphenyl) -3,3-dimethyl-4-methylcyclohexane, 1,1-bis (3-bromo-4-hydroxyphenyl) ) -3,3-dimethyl-5-methylcyclopentane.

  1,1-bis (3,5-substituted-4-hydroxyphenyl) -alkylcycloalkane includes 1,1-bis (4-hydroxyphenyl) substituted with an alkyl group having 1 to 12 carbon atoms or a halogen group. Alkylcycloalkanes such as 1,1-bis (3-methyl-4-hydroxyphenyl) -3,3,5-trimethylcyclohexane, 1,1-bis (3,5-dichloro-4-hydroxyphenyl)- 3,3-dimethyl-5-methylcyclohexane, 1,1-bis (3-ethyl-5-methyl-4-hydroxyphenyl) -3,3,5-trimethylcyclohexane, 1,1-bis (3,5- Dimethyl-4-hydroxyphenyl) -3,3,5-trimethylcyclohexane, 1,1-bis (3,5-dimethyl-4-hydroxyphenyl) -3,3-di Chill -5-methyl cyclopentane, and the like.

  Examples of 9,9-bis (4-hydroxyphenyl) fluorenes include 9,9-bis (4-hydroxyphenyl) fluorene, 9,9-bis (3-methyl-4-hydroxyphenyl) fluorene, Examples include 9-bis (3-ethyl-4-hydroxyphenyl) fluorene.

  Furthermore, as other bisphenol components, 2,2′-bis (4-hydroxyphenyl) propane (bisphenol-A), 4,4 ′-(α-methylbenzylidene) bisphenol, bis (4-hydroxyphenyl) methane, 2 , 2′-bis (4-hydroxyphenyl) butane, 3,3′-bis (4-hydroxyphenyl) pentane, 4,4′-bis (4-hydroxyphenyl) hebutane, 4,4′-bis (4- Hydroxyphenyl) 2,5-dimethylhebutane, bis (4-hydroxyphenyl) methylphenylmethane, bis (4-hydroxyphenyl) diphenylmethane, 2,2′-bis (4-hydroxyphenyl) octane, bis (4-hydroxy) Phenyl) octane, bis (4-hydroxyphenyl) 4-fluorophenylmethane, 2,2 -Bis (3-fluoro-4-hydroxyphenyl) propane, bis (3,5-dimethyl-4hydroxyphenyl) methane, 2,2'-bis (3,5-dimethyl-4-hydroxyphenyl) propane, bis (3 , 5-dimethyl-4-hydroxyphenyl) phenylethane, bis (3-methyl-4-hydroxyphenyl) diphenylmethane, and the like. These may be used alone or in combination of two or more.

In addition to the bisphenol component, the polycarbonate contains a polyester carbonate using a small amount of aliphatic or aromatic dicarboxylic acid as a comonomer of the acid component.
Examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, p-xylene glycol, bis (4-hydroxyphenyl) -methane, 1,1′-bis (4-hydroxyphenyl) -ethane, and 1,1′-. Bis (4-hydroxyphenyl) -butane, 2,2′-bis (4-hydroxyphenyl) -butane and the like can be mentioned. Of these, terephthalic acid and isophthalic acid are preferred.

The viscosity average molecular weight of the polycarbonate used is preferably from 2,000 to 100,000, more preferably from 5,000 to 70,000, still more preferably from 7,000 to 50,000.
It is preferably 0.07 to 2.70, more preferably 0.15 to 1.80, and more preferably 0.20 to 1.30, expressed as a specific viscosity measured at 20 ° C. in a methylene chloride solution having a concentration of 0.7 g / dL. Is more preferable. A film having a viscosity average molecular weight of less than 2,000 is not suitable because the resulting film becomes brittle, and a film having a viscosity average molecular weight of 100,000 or more is not preferable because processability to the film becomes difficult.

  As in the case of the polyester resin, an ultraviolet absorber can be added to the polycarbonate resin as necessary. Moreover, a dry process and an easy-adhesion process can be performed in order to strengthen adhesiveness with a polarizer.

  Examples of the method for producing a film from a polycarbonate-based resin include a solution casting method, a melt extrusion method, a calendering method, etc., but excellent in thickness uniformity and no optical defects such as gel, butts, fish eyes, and scratches do not occur. The method is desirable.

<< Cycloolefin resin >>
The cycloolefin-based resin is a thermoplastic resin having a monomer unit composed of a cyclic olefin (cycloolefin) such as norbornene or a polycyclic norbornene-based monomer.
This cycloolefin-based resin can be a hydrogenated product of a ring-opening polymer of cycloolefin or a ring-opening copolymer using two or more kinds of cycloolefins, as well as a cycloolefin and a chain olefin or a vinyl group. An addition copolymer with an aromatic compound having
The norbornene-based resin has a norbornene skeleton in its repeating unit, and examples thereof include known resins disclosed in JP-A-3-14882 and JP-A-3-122137. In the present invention, these conventionally known norbornene resins can be suitably used. For example, a ring-opening polymer hydrogenated product of a norbornene monomer, an addition polymer of a norbornene monomer, a norbornene monomer, ethylene, Addition polymer of olefin monomer such as α-olefin; addition polymer of norbornene monomer and cyclic olefin monomer such as cyclopentene, cyclooctene, 5,6-dihydrodicyclopentadiene, and modification of these polymers Thing etc. are mentioned.

  Examples of the norbornene-based monomer include norbornene, 5-methyl-2-norbornene, 5-ethyl-2-norbornene, 5-butyl-2-norbornene, 5-ethylidene-2-norbornene, and 5-methoxycarbonyl-2- Norbornene, 5,5-dimethyl-2-norbornene, 5-cyano-2-norbornene, 5-methyl-5-methoxycarbonyl-2-norbornene, 5-phenyl-2-norbornene, 5-phenyl-5-methyl-2 -Norbornene, ethylene-tetracyclododecene copolymer, 6-methyl-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-ethyl -1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-ethyl 1,4: 5,8-ethylidene-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-chloro-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-cyano-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6- Pyridyl-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-methoxycarbonyl-1,4: 5,8-dimethano-1,4 , 4a, 5,6,7,8,8a-octahydronaphthalene, 1,4-dimethano-1,4,4a, 4b, 5,8,8a, 9a-octahydrofluorene, 5,8-methano-1 , 2,3,4,4a, 5,8,8a-octahydro-2.3-cyclopentadi Nonaphthalene, 4,9: 5,8-dimethano-3a, 4,4a, 5,8,8a, 9,9a-octahydro-1H-benzoindene, 4,11: 5,10: 6,9-trimethano- 3a, 4, 4a, 5, 5a, 6, 9, 9a, 10, 10a, 11, 11a-dodecahydro-1H-cyclopentanthracene and the like.

The polymerization method of the norbornene-based monomer may be a known method. If necessary, the norbornene-based monomer can be copolymerized with another copolymerizable monomer or hydrogenated to obtain a norbornene-based polymer hydrogenated product.
In addition, polymers and polymer hydrogenated substances are formed by known methods using an α, β-unsaturated carboxylic acid and derivatives thereof, styrene hydrocarbons, olefinic unsaturated bonds, and organic groups having hydrolyzable groups. Modification may be made using a silicon compound, an unsaturated epoxy monomer, or the like.

In the above polymerization, a hydrated salt of Ir, Os, Ru trichloride, MoC ₁₅ , WC ₁₆ , ReCl ₅ , (C ₂ H ₅ ) ₃ Al, (C ₂ H ₅ ) ₃ Al / TiCl ₄ is used as a polymerization medium. , (Π-C ₄ H ₇ ) ₄ Mo / TiCl ₄ , (π-C ₄ H ₇ ) ₄ W / TiCl ₄ , (π-C ₃ H ₅ ) ₃ Cr / WCl _{6 and the} like. .

  Examples of the norbornene-based resin include those manufactured by Nippon Zeon Co., Ltd., trade names “ZEONOR” and “ZEONEX”; manufactured by JSR Corporation, trade name “ARTON”; manufactured by Hitachi Chemical Co., Ltd., trade name “OPTOREZ”; Product names such as “APEL” are commercially available.

  Similarly to the polyester resin, the norbornene resin can be added with an ultraviolet absorber as necessary. Moreover, a dry process and an easy-adhesion process can be performed in order to strengthen adhesiveness with a polarizer.

[Method for producing norbornene-based resin film]
The norbornene resin film can be formed by a melt molding method.
Examples of the melt molding method include a method using a T die, a melt extrusion method such as an inflation method, a calendar method, a heat press method, and an injection molding method. Among them, a melt extrusion method using a T die that has a small thickness unevenness, can be easily processed to a thickness of about 50 to 500 μm, and can reduce the absolute value of retardation and its variation is preferable.

The conditions of the melt molding method are the same as those used for the polycarbonate resin having the same Tg. For example, in the melt extrusion method using a T-die, it is preferable to select conditions under which the resin can be gradually cooled with a resin temperature of about 240 to 300 ° C. and a take-up roll temperature of about 100 to 150 ° C.
Further, in order to reduce surface defects such as a die line, the die needs to have a structure in which the staying portion is reduced as much as possible, and it is preferable to use a die having no damage or the like in the die or the lip.

  Moreover, the surface accuracy of these sheets can be further improved by polishing the surface as necessary.

<Second protective film>
As the second protective film, a cellulose acylate film is used from the viewpoint of productivity at the time of polarizing plate processing. In particular, in-plane retardation (Re10) at 25 ° C. and 10% relative humidity and 25 ° C. and 80% relative humidity are used. A film having a Gr of 0.06 or more obtained by dividing the difference from the in-plane retardation (Re80) by the in-plane retardation (Re60) at 25 ° C. and a relative humidity of 60% can be more preferably used.
Hereinafter, cellulose acylate will be described in detail.

Examples of cellulose as a cellulose acylate raw material used in the present invention include cotton linter and wood pulp. Any cellulose acylate obtained from any raw material cellulose may be used, or a mixture thereof may be used.
Moreover, in this invention, the cellulose acylate with which the substitution degree to the hydroxyl group of a cellulose satisfies all of following formula (I)-(II) is used more preferable.
2.30 ≤ SA + SB <2.80 ... Formula (I)
0 ≦ SB ≦ 1.00 ········································· Formula (II)
Here, in the formulas (I) to (II), SA and SB each represent a substituent of an acyl group substituted with a hydroxyl group of cellulose, SA represents a substitution degree of an acetyl group, and SB represents 3 to 4 carbon atoms. The degree of substitution of the acyl group.

Glucose units having β-1,4 bonds constituting cellulose have free hydroxyl groups at the 2nd, 3rd and 6th positions. Cellulose acylate is a polymer obtained by esterifying some or all of these hydroxyl groups with acyl groups. The degree of acyl substitution means the proportion of cellulose esterified at each of the 2nd, 3rd and 6th positions (100% esterification has a degree of substitution of 1).
In the present invention, from the viewpoint of expression of optical anisotropy, the total sum of substitution degrees of hydroxyl groups SA and SB is preferably 2.30 ≦ SA + SB <2.80, and more preferably 2.30 ≦ SA + SB <2.60. .
In addition, there existed a problem that birefringence became easy to express and moisture permeability became large, so that the sum total of substitution degree was small. Therefore, the present inventors set the moisture permeability of the first protective film to 300 g / m ² · day or less, so that even when a cellulose acylate film of 2.30 ≦ SA + SB <2.80 is used, the optical characteristics It was found that the change in retardation due to the change in humidity was suppressed.

  The basic principle of the method for synthesizing cellulose acylate, which is a cellulose derivative used in the present invention, is described in Ueda et al., Wood Chemistry, 180-190 (Kyoritsu Shuppan, 1968). A typical synthesis method is a liquid phase acetylation method using a carboxylic acid anhydride-acetic acid-sulfuric acid catalyst. The cellulose derivative film used in the present invention is preferably composed of a cellulose derivative in which the polymer component constituting the film substantially has the above definition. “Substantially” means 55% by mass or more (preferably 70% by mass or more, more preferably 80% by mass or more) of the polymer component. As a raw material for film production, it is preferable to use cellulose derivative particles. 90% by mass or more of the particles to be used preferably have a particle diameter of 0.5 to 5 mm. Moreover, it is preferable that 50 mass% or more of the particle | grains to be used have a particle diameter of 1-4 mm. The cellulose derivative particles preferably have a shape as close to a sphere as possible.

The degree of polymerization of the cellulose derivative preferably used in the present invention is preferably a viscosity average degree of polymerization of 200 to 700, more preferably 250 to 550, still more preferably 250 to 400, and particularly preferably 250 to 350.
The average degree of polymerization can be measured by Uda et al.'S intrinsic viscosity method (Kazuo Uda, Hideo Saito, Journal of Textile Society, Vol. 18, No. 1, pages 105-120, 1962). Further, it is described in detail in JP-A-9-95538.
The cellulose acylate used in the present invention preferably has a narrow molecular weight distribution of Mw / Mn (Mw is a mass average molecular weight, Mn is a number average molecular weight) by gel permeation chromatography. The range of Mw / Mn is preferably 1.0 to 1.7, more preferably 1.3 to 1.65, and still more preferably 1.4 to 1.6.

<< Cellulose acylate film with maximum refractive index in film thickness direction >>
From the viewpoint of optical compensation, a cellulose acylate film having a maximum refractive index in the film thickness direction may be used as the second protective film.
The driving mode of the liquid crystal cell is not particularly limited and is appropriately selected according to the purpose. For example, it is preferably used in the IPS mode, ECB mode, and VA mode, and more preferably in the IPS mode.
The substituent linked to the three hydroxyl groups on the β-glucose ring, which is a constituent unit of cellulose acylate, preferably has a substituent having a large polarizability anisotropy. By introducing a substituent having a large polarizability anisotropy into cellulose acylate and adjusting the other substituent and the degree of substitution, an optical compensation film having a maximum refractive index in the film thickness direction can be obtained.

[Distance between substituent ends and polarizability anisotropy]
The end-to-end distance of the substituent of the cellulose derivative having the maximum refractive index in the film thickness direction and the polarizability anisotropy were calculated using Gaussian 03 (Revision B.03, US Gaussian Software).
The end-to-end distance was calculated as the distance between the most distant atoms after structural optimization by calculation of the B3LYP / 6-31G ^* level.
The polarizability anisotropy is calculated using the structure optimized at the B3LYP / 6-31G ^* level, after calculating the polarizability at the 3LYP / 6-311 + G ^** level and diagonalizing the obtained polarizability tensor. Calculated from the diagonal component.
In the calculation of the distance between the terminals of the substituent and the polarizability anisotropy, the substituent linked to the hydroxyl group on the β-glucose ring, which is the structural unit of the cellulose derivative, is calculated with the partial structure including the oxygen atom of the hydroxyl group. And asked.

The polarizability anisotropy of the cellulose derivative having the maximum refractive index in the film thickness direction is defined by the following mathematical formula (A). In the following formula (A), αx, αy, and αz are eigenvalues obtained after diagonalizing the polarizability tensor, and αx ≧ αy ≧ αz.
Δα = αx− (αy + αz) / 2 Equation (A)

The polarizability anisotropy is related to the expression of the refractive index in the direction perpendicular to the stretching during film stretching. That is, when the polarizability anisotropy is small, a slow axis appears in the stretching direction, and when the polarizability anisotropy is large, a slow axis appears in the stretching orthogonal direction.
In order to obtain an optical compensation film having a negative retardation value in the thickness direction, the polarizability anisotropy is preferably as large as possible, more preferably 2.5 × 10 ⁻²⁴ cm ⁻³ or more, More preferably, it is 3.5 × 10 ⁻²⁴ cm ⁻³ or more, and particularly preferably 4.5 × 10 ⁻²⁴ cm ⁻³ or more.

A preferable cellulose derivative having a maximum refractive index in the film thickness direction is preferably a mixed acid ester having a fatty acid acyl group and a substituted or unsubstituted aromatic acyl group.
Here, examples of the substituted or unsubstituted aromatic acyl group include groups represented by the following general formula (A).

First, the general formula (A) will be described. In the general formula (A), X is a substituent. Examples of the substituent include a halogen atom, cyano, alkyl group, alkoxy group, aryl group, aryloxy group, acyl group, carbonamido group, and sulfonamide group. Ureido group, aralkyl group, nitro, alkoxycarbonyl group, aryloxycarbonyl group, aralkyloxycarbonyl group, carbamoyl group, sulfamoyl group, acyloxy group, alkenyl group, alkynyl group, alkylsulfonyl group, arylsulfonyl group, alkyloxysulfonyl group , Aryloxysulfonyl group, alkylsulfonyloxy group, and aryloxysulfonyl group, —S—R, —NH—CO—OR, —PH—R, —P (—R) ₂ , —PH—O—R, — P (—R) (— O—R), —P (—O—R) ₂ , —P H (= O) -R-P (= O) (-R) ₂ , -PH (= O) -O-R, -P (= O) (-R) (-O-R), -P ( ═O) (— O—R) ₂ , —O—PH (═O) —R, —O—P (═O) (— R) ₂ —O—PH (═O) —O—R, —O -P (= O) (-R) (-O-R), -O-P (= O) (-O-R) ₂ , -NH-PH (= O) -R, -NH-P (= O) (— R) (— O—R), —NH—P (═O) (— O—R) ₂ , —SiH ₂ —R, —SiH (—R) ₂ , —Si (—R) ₃ , —O—SiH ₂ —R, —O—SiH (—R) ₂ , and —O—Si (—R) ₃ .

R is an aliphatic group, an aromatic group or a heterocyclic group. The number of substituents is preferably 1 to 5, more preferably 1 to 4, more preferably 1 to 3, and particularly preferably 1 or 2.
As the substituent, a halogen atom, a cyano group, an alkyl group, an alkoxy group, an aryl group, an aryloxy group, an acyl group, a carbonamido group, a sulfonamide group, and a ureido group are preferable. Group, an alkyl group, an alkoxy group, an aryloxy group, an acyl group, and a carbonamido group are more preferable. Among these, a halogen atom, a cyano group, an alkyl group, an alkoxy group, and an aryloxy group are more preferable, and among these, , A halogen atom, an alkyl group, and an alkoxy group are particularly preferable. Among these, an alkyl group is particularly preferable.

The halogen atom includes a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.
Examples of the alkyl group include methyl, ethyl, propyl, isopropyl, butyl, t-butyl, hexyl, cyclohexyl, octyl, and 2-ethylhexyl.
The alkoxy group may have a cyclic structure or a branch. The number of carbon atoms of the alkoxy group is preferably 1 to 20, more preferably 1 to 12, still more preferably 1 to 6, and particularly preferably 1 to 4.
The alkoxy group may be further substituted with another alkoxy group. Examples of alkoxy groups include methoxy, ethoxy, 2-methoxyethoxy, 2-methoxy-2-ethoxyethoxy, butyloxy, hexyloxy, and octyloxy.

The aryl group preferably has 6 to 20 carbon atoms, and more preferably 6 to 12 carbon atoms. Examples of the aryl group include phenyl and naphthyl.
The number of carbon atoms in the aryloxy group is preferably 6 to 20, and more preferably 6 to 12. Examples of the aryloxy group include phenoxy and naphthoxy.
The acyl group preferably has 1 to 20 carbon atoms, and more preferably 1 to 12 carbon atoms. Examples of the acyl group include formyl, acetyl, and benzoyl.
Further, the carbonamide group has preferably 1 to 20 carbon atoms, and more preferably 1 to 12 carbon atoms. Examples of the carbonamido group include acetamide and benzamide.
The number of carbon atoms in the sulfonamide group is preferably 1 to 20, and more preferably 1 to 12. Examples of the sulfonamide group include methanesulfonamide, benzenesulfonamide, and p-toluenesulfonamide.
The number of carbon atoms in the ureido group is preferably 1 to 20, and more preferably 1 to 12. Examples of the ureido group include (unsubstituted) ureido.

The alkyl group may have a cyclic structure or a branch.
The alkyl group preferably has 1 to 20 carbon atoms, more preferably 1 to 12 carbon atoms, still more preferably 1 to 6 carbon atoms, and particularly preferably 1 to 4 carbon atoms.
The number of carbon atoms in the aralkyl group is preferably 7 to 20, and more preferably 7 to 12. Examples of the aralkyl group include benzyl, phenethyl, and naphthylmethyl.
The number of carbon atoms of the alkoxycarbonyl group is preferably 1-20, and more preferably 2-12. Examples of the alkoxycarbonyl group include methoxycarbonyl.
The aryloxycarbonyl group preferably has 7 to 20 carbon atoms, and more preferably 7 to 12 carbon atoms. Examples of the aryloxycarbonyl group include phenoxycarbonyl.
The number of carbon atoms in the aralkyloxycarbonyl group is preferably 8 to 20, and more preferably 8 to 12. Examples of the aralkyloxycarbonyl group include benzyloxycarbonyl.
The carbamoyl group preferably has 1 to 20 carbon atoms, and more preferably 1 to 12 carbon atoms. Examples of the carbamoyl group include (unsubstituted) carbamoyl and N-methylcarbamoyl.
Further, the number of carbon atoms of the sulfamoyl group is preferably 20 or less, and more preferably 12 or less. Examples of the sulfamoyl group include (unsubstituted) sulfamoyl and N-methylsulfamoyl.
The acyloxy group preferably has 1 to 20 carbon atoms, and more preferably 2 to 12 carbon atoms. Examples of the acyloxy group include acetoxy and benzoyloxy.

The alkenyl group has preferably 2 to 20 carbon atoms, and more preferably 2 to 12 carbon atoms. Examples of the alkenyl group include vinyl, allyl, and isopropenyl.
The alkynyl group preferably has 2 to 20 carbon atoms, and more preferably 2 to 12 carbon atoms. Examples of the alkynyl group include thienyl.
The number of carbon atoms in the alkylsulfonyl group is preferably 1-20, and more preferably 1-12.
The number of carbon atoms in the arylsulfonyl group is preferably 6 to 20, and more preferably 6 to 12.
The alkyloxysulfonyl group preferably has 1 to 20 carbon atoms, and more preferably 1 to 12 carbon atoms.
The aryloxysulfonyl group preferably has 6 to 20 carbon atoms, and more preferably 6 to 12 carbon atoms.

Next, in the fatty acid ester residue in the cellulose mixed acid ester, the aliphatic acyl group has 2 to 20 carbon atoms, specifically acetyl, propionyl, butyryl, isobutyryl, valeryl, pivaloyl, hexanoyl, octanoyl, lauroyl, stearoyl. Etc. Among these, acetyl, propionyl, and butyryl are preferable, and among these, acetyl is more preferable.
In the present invention, the aliphatic acyl group is meant to include those further having a substituent, and examples of the substituent include those exemplified as X in the general formula (A).

  In the general formula (A), the number (n) of substituents X substituted on the aromatic ring is preferably 0 or 1 to 5, more preferably 1 to 3. Or it is more preferable that it is two.

  Furthermore, when the number of substituents substituted on the aromatic ring is 2 or more, the substituents may be the same as or different from each other. Further, they may be linked to each other to form a condensed polycyclic compound (for example, naphthalene, indene, indane, phenanthrene, quinoline, isoquinoline, chromene, chroman, phthalazine, acridine, indole, indoline, etc.).

Next, the substitution of the aromatic acyl group to the hydroxyl group of cellulose is generally performed by a method using an aromatic carboxylic acid claloid, a symmetric acid anhydride derived from an aromatic carboxylic acid, or a mixed acid anhydride, etc. As a particularly preferred method, a method using an acid anhydride derived from an aromatic carboxylic acid (described in Journal of Applied Polymer Science, Vol. 29, 3981-3990 (1984)) can be mentioned.
As a manufacturing method of the said cellulose mixed acid ester compound by said method, after manufacturing (1) cellulose fatty acid monoester or diester once, the aromatic acyl group represented by the said General formula (A) is represented by the remaining hydroxyl group. (2) A method of reacting a mixed acid anhydride of an aliphatic carboxylic acid and an aromatic carboxylic acid directly with cellulose, and the like.
In the above method (1), the cellulose fatty acid ester or diester production method itself is a well-known method, but the subsequent reaction of introducing an aromatic acyl group into this further depends on the type of the aromatic acyl group. Although it differs, it is preferable that reaction temperature is 0-100 degreeC, and it is more preferable that it is 20-50 degreeC.
The reaction time is preferably 30 minutes or more, and more preferably 30 to 300 minutes.
In the method using the mixed acid anhydride in (2) above, the reaction conditions vary depending on the type of the mixed acid anhydride, but the reaction temperature is preferably 0 to 100 ° C, more preferably 20 to 50 ° C. preferable.
The reaction time is preferably 30 to 300 minutes, more preferably 60 to 200 minutes.
Any of the reactions (1) to (2) may be carried out either without solvent or in a solvent, but is preferably carried out using a solvent. Examples of the solvent include dichloromethane, chloroform, dioxane and the like.

The degree of substitution is 3.0 when 100% of the hydroxyl groups of cellulose are substituted. The degree of substitution can be determined from the peak intensity of the carbonyl carbon in the acyl group in C ¹³ -NMR.
In the case of a cellulose fatty acid monoester, the substitution degree of the aromatic acyl group is preferably 2.0 or less, more preferably 0.1 to 2.0, more preferably 0.1 to 1.0, relative to the remaining hydroxyl group. More preferably.
In addition, the substitution degree of cellulose fatty acid diester (cellulose diacetate) is preferably 1.0 or less, more preferably 0.1 to 1.0 with respect to the remaining hydroxyl group. Furthermore, the total substitution degree PA of the cellulose acylate is preferably 2.4-3.

  In order to express negative Rth, it is preferable to introduce a substituent having a large polarizability anisotropy at the 2nd and 3rd positions of the β-glucose ring. In the 2nd and 3rd positions, the substituent introduced with a lower degree of freedom than the 6th position where the substituent is introduced from the β-glucose ring via the carbon atom is easily oriented in the film thickness direction. It is presumed that it is easily oriented.

Specific examples of the aromatic acyl group represented by formula (A) are shown below, but the present invention is not limited thereto.
In the present invention, the aromatic acyl group represented by the general formula (A) is preferably 1, 3, 5, 6, 8, 13, 18, and 28 in the numbers in the following specific examples. 1, 3, 6, and 13 are more preferable.

The cellulose acylate having the maximum refractive index in the film thickness direction preferably has a mass average degree of polymerization of 350 to 800, more preferably 370 to 600.
In addition, the cellulose acylate having the maximum refractive index in the film thickness direction preferably has a number average molecular weight of 70,000 to 230,000, and more preferably has a number average molecular weight of 75,000 to 230,000. Preferably, it has a number average molecular weight of 78,000 to 120,000.

As the acylating agent, an acid anhydride or an acid chloride can be used.
When the acylating agent is an acid anhydride, an organic acid (for example, acetic acid) or methylene chloride is used as a reaction solvent. As the catalyst, a protic catalyst such as sulfuric acid is used.
When the acylating agent is an acid chloride, a basic compound is used as a catalyst.
In the most general synthetic method in the industry, cellulose is an organic acid (acetic acid, propionic acid, butyric acid) corresponding to acetyl group and other acyl groups, or an acid anhydride thereof (acetic anhydride, propionic anhydride, butyric anhydride). A method of synthesizing a cellulose ester by esterification with a mixed organic acid component containing) is known.

In this method, cellulose such as cotton linter and wood pulp is activated with an organic acid such as acetic acid, and then esterified using a mixture of organic acid components as described above in the presence of a sulfuric acid catalyst. There are many cases to do.
The organic acid anhydride component is generally used in excess with respect to the amount of hydroxyl groups present in the cellulose.
In this esterification treatment, in addition to the esterification reaction, a hydrolysis reaction (depolymerization reaction) of the cellulose main chain β1 → 4-glycoside bond) proceeds.
When the hydrolysis reaction of the main chain proceeds, the degree of polymerization of the cellulose ester is lowered, and the physical properties of the cellulose ester film to be produced are lowered.
Therefore, the reaction conditions such as the reaction temperature are preferably determined in consideration of the degree of polymerization and molecular weight of the obtained cellulose ester.

In order to obtain a cellulose ester having a high degree of polymerization (high molecular weight), it is important to adjust the maximum temperature in the esterification reaction step to 50 ° C. or lower.
The maximum temperature is preferably adjusted to 35 to 50 ° C, more preferably 37 to 47 ° C. A reaction temperature of 35 ° C. or higher is preferable because the esterification reaction proceeds smoothly. A reaction temperature of 50 ° C. or lower is preferable because inconveniences such as a decrease in the degree of polymerization of the cellulose ester do not occur.

After the esterification reaction, when the reaction is stopped while suppressing a temperature rise, a decrease in the polymerization degree can be further suppressed, and a cellulose ester having a high polymerization degree can be synthesized.
That is, when a reaction terminator (for example, water, acetic acid) is added after completion of the reaction, the excess acid anhydride that has not participated in the esterification reaction is hydrolyzed to form a corresponding organic acid.
This hydrolysis reaction is accompanied by intense heat generation, and the temperature in the reactor rises.
If the rate of addition of the reaction terminator is not too high, heat is rapidly generated exceeding the cooling capacity of the reactor, the hydrolysis reaction of the cellulose main chain proceeds significantly, and the degree of polymerization of the resulting cellulose ester decreases. Such a problem does not occur.
In addition, a part of the catalyst is bonded to the cellulose during the esterification reaction, and most of the catalyst is dissociated from the cellulose during the addition of the reaction terminator.
At this time, if the rate of addition of the reaction terminator is not too high, a sufficient reaction time is ensured for the catalyst to dissociate, and problems such as part of the catalyst remaining in a state of being bound to cellulose are unlikely to occur.
Cellulose esters to which a strong acid catalyst is partially bonded are very poor in stability, and are easily decomposed by heat during drying of the product to lower the degree of polymerization.
For these reasons, after the esterification reaction, the reaction is preferably stopped by adding a reaction terminator over a period of preferably 4 minutes or longer, more preferably 4 to 30 minutes. In addition, it is preferable if the addition time of the reaction terminator is 30 minutes or less because problems such as a decrease in industrial productivity do not occur.

  As the reaction terminator, water or alcohol that decomposes an acid anhydride is generally used. However, in the present invention, a mixture of water and an organic acid is preferably used as a reaction terminator in order not to precipitate triesters having low solubility in various organic solvents. When the esterification reaction is carried out under the above conditions, a high molecular weight cellulose ester having a mass average polymerization degree of 500 or more can be easily synthesized.

<< Manufacture of cellulose acylate film >>
The cellulose acylate film is produced by a solvent cast method. In the solvent cast method, a film is produced using a solution (dope) in which cellulose acylate is dissolved in an organic solvent.
Next, the organic solvent in which the cellulose derivative is dissolved will be described.
First, a chlorinated organic solvent that is preferably used in preparing a cellulose derivative solution will be described.
The chlorinated organic solvent is not particularly limited as long as the object can be achieved within the range in which the cellulose derivative can be dissolved, cast and film-formed.
These chlorinated organic solvents are preferably dichloromethane and chloroform. Particularly preferred is dichloromethane.
In addition, there is no particular problem in mixing an organic solvent other than the chlorinated organic solvent. In that case, it is preferable to use at least 50% by mass of dichloromethane.
The non-chlorine organic solvent used in combination is described below. That is, as a preferable non-chlorine organic solvent, a solvent selected from esters, ketones, ethers, alcohols, hydrocarbons and the like having 3 to 12 carbon atoms is preferable. The ester, ketone, ether and alcohol may have a cyclic structure.

In addition, the alcohol used in combination with the chlorinated organic solvent may be linear, branched or cyclic, and is preferably a saturated aliphatic hydrocarbon. The hydroxyl group of the alcohol may be any of primary to tertiary.
Examples of the alcohol include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, t-butanol, 1-pentanol, 2-methyl-2-butanol and cyclohexanol.
In addition, as alcohol, a fluorine-type alcohol is also used. Examples thereof include 2-fluoroethanol, 2,2,2-trifluoroethanol, 2,2,3,3-tetrafluoro-1-propanol and the like.
Furthermore, the hydrocarbon may be linear, branched or cyclic. Either aromatic hydrocarbons or aliphatic hydrocarbons can be used. The aliphatic hydrocarbon may be saturated or unsaturated. Examples of hydrocarbons include cyclohexane, hexane, benzene, toluene, and xylene.

Next, a non-chlorine solvent will be described. In the present invention, the non-chlorine organic solvent is not particularly limited as long as the object can be achieved as long as the cellulose derivative can be dissolved, cast, and formed into a film.
The non-chlorine organic solvent is preferably a solvent selected from esters, ketones and ethers having 3 to 12 carbon atoms. The ester, ketone and ether may have a cyclic structure.
A compound having two or more functional groups of esters, ketones and ethers (that is, —O—, —CO—, and —COO—) can also be used as a main solvent. Such other functional groups may be included.
In the case of the main solvent having two or more kinds of functional groups, the number of carbon atoms may be within the specified range of the compound having any functional group.
Examples of the esters having 3 to 12 carbon atoms include ethyl formate, propyl formate, pentyl formate, methyl acetate, ethyl acetate and pentyl acetate.
Examples of ketones having 3 to 12 carbon atoms include acetone, methyl ethyl ketone, diethyl ketone, diisobutyl ketone, cyclopentanone, cyclohexanone, and methylcyclohexanone.
Examples of ethers having 3 to 12 carbon atoms include diisopropyl ether, dimethoxymethane, dimethoxyethane, 1,4-dioxane, 1,3-dioxolane, tetrahydrofuran, anisole and phenetole.
Examples of the organic solvent having two or more kinds of functional groups include 2-ethoxyethyl acetate, 2-methoxyethanol and 2-butoxyethanol.

  The non-chlorine organic solvent used in the above cellulose derivative is selected from the various viewpoints described above, and is preferably as follows. That is, a preferred solvent for the cellulose derivative is a mixed solvent of three or more different from each other, and the first solvent is at least one selected from methyl acetate, ethyl acetate, methyl formate, ethyl formate, acetone, dioxolane, dioxane, or the like. The second solvent is selected from ketones having 3 to 7 carbon atoms or acetoacetate, and the third solvent is selected from alcohols or hydrocarbons having 1 to 10 carbon atoms, More preferably, it is a C1-C8 alcohol. Note that when the first solvent is a mixed liquid of two or more kinds of solvents, the second solvent may be omitted. The first solvent is more preferably methyl acetate, acetone, methyl formate, ethyl formate, or a mixture thereof, and the second solvent is preferably acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, or methyl acetyl acetate. It may be a mixed liquid.

  Although 10-30 mass% of cellulose derivatives are melt | dissolved in the organic solvent, More preferably, it is 13-27 mass%, It is preferable that it is the cellulose derivative solution which melt | dissolved especially 15-25 mass%. The method of carrying out the cellulose derivative at these concentrations may be carried out so that the cellulose derivative has a predetermined concentration at the stage of dissolution. Alternatively, the cellulose derivative is prepared in advance as a low-concentration solution (for example, 9 to 14% by mass) and then the concentration step is performed. It may be adjusted to a high concentration solution. Furthermore, it is good also as a cellulose derivative solution of a predetermined | prescribed low concentration by adding a various additive later after making a cellulose derivative solution of a high concentration beforehand.

[Additive]
In the cellulose acylate solution, various additives (for example, plasticizers, ultraviolet inhibitors, deterioration inhibitors, optical anisotropy control agents, fine particles, release agents, infrared absorbers) according to applications in each preparation step. , Etc.), which may be solid or oily. That is, the melting point and boiling point are not particularly limited. For example, mixing of ultraviolet absorbing material at 20 ° C. or lower and 20 ° C. or higher, and similarly, mixing of a plasticizer is described in, for example, JP-A-2001-151901. Furthermore, infrared absorbing dyes are described, for example, in JP-A No. 2001-194522. Moreover, the addition time may be added at any time in the dope preparation process, but may be added by adding an additive to the final preparation process of the dope preparation process. Furthermore, the amount of each material added is not particularly limited as long as the function is exhibited. Moreover, when a cellulose acylate film is formed from a multilayer, the kind and addition amount of the additive of each layer may differ. For example, they are described in JP-A No. 2001-151902, and these are conventionally known techniques.
Conventionally proposed materials can be used as materials for reducing moisture permeability.
Japanese Patent Application Laid-Open No. 2002-22956 discloses a method of adding a polymerized plasticizer to cellulose acylate.
Japanese Patent Application Laid-Open No. 2002-146044 discloses a method using a rosin plasticizer.
Japanese Patent Laid-Open No. 2001-343528 discloses a method in which a hydrophobic plasticizer and a deterioration inhibitor are used in combination.
Japanese Patent Laid-Open No. 2002-14230 discloses the use of a compound containing two or more aromatic rings.
Japanese Patent Application Laid-Open No. 9-90101 proposes a method of changing a substituent of cellulose acylate to a hydrophobic one.
More specific materials are exemplified below, but the moisture permeability control agent usable in the present invention is not limited to the following.

[Retardation raising agent]
An aromatic compound having at least two aromatic rings can be used as a retardation increasing agent in order to increase the retardation of the second protective film placed opposite to the liquid crystal cell. Examples of the retardation increasing agent include aromatic compounds having at least two aromatic rings such as triazines (triphenyl-1,3,5-triazine, tri-m-tolyl-1,3,5-triazine, etc.). , Trans-1,4-cyclohexanedicarboxylic acid diesters (p-n-hexylphenol diester, pn-amylphenol diester, etc.).
Other specific examples are described in JP-A Nos. 2000-1111914, 2000-275434, PCT / JP00 / 02619, and the like. Two or more aromatic compounds may be used in combination. The aromatic ring of the aromatic compound includes an aromatic heterocyclic ring in addition to the aromatic hydrocarbon ring.
The molecular weight of the retardation increasing agent is preferably 300 to 800. When using a cellulose acylate film as a cell side protective film, an aromatic compound is used in 0.01-20 mass parts with respect to 100 mass parts of cellulose acylates. The aromatic compound is preferably used in the range of 0.05 to 15 parts by mass and more preferably in the range of 0.1 to 10 parts by mass with respect to 100 parts by mass of the cellulose acylate.

The retardation of the second protective film placed opposite to the liquid crystal cell can be reduced by a conventionally known additive. JP-A-11-246704, JP-A-92574 and JP-A-2000-63560 propose a method for reducing the birefringence by specifying the type of plasticizer added to the cellulose acylate film.
Further, for these details, materials described in detail on pages 16 to 22 in the Japan Institute of Invention Disclosure Bulletin (Public Technical Number 2001-1745, issued on March 15, 2001, Japan Institute of Invention) are preferably used.
The air-side protective film needs to be added with an ultraviolet ray inhibitor, but the cell-side protective film does not necessarily need to be added with an ultraviolet ray-resistant agent.

[Dope preparation]
A cellulose acylate solution can be prepared by a general method comprising treatment at a temperature of 0 ° C. or higher (normal temperature or high temperature). The solution can be prepared by using a dope preparation method and apparatus in a normal solvent cast method. In the case of a general method, it is preferable to use a halogenated hydrocarbon (particularly methylene chloride) as the organic solvent. The amount of cellulose acylate is adjusted so as to be contained in the obtained solution in an amount of 10 to 40% by mass. The amount of cellulose acylate is more preferably 10 to 30% by mass. Arbitrary additives described later may be added to the organic solvent (main solvent).
The solution can be prepared by stirring the cellulose acylate and the organic solvent at room temperature (0 to 40 ° C.). The high concentration solution may be stirred under pressure and heating conditions. Specifically, the cellulose acylate and the organic solvent are placed in a pressure vessel and sealed, and stirred while being heated to a temperature equal to or higher than the boiling point of the solvent at normal temperature and in a range where the solvent does not boil.
The heating temperature is usually preferably 40 ° C. or higher, more preferably 60 to 200 ° C., and still more preferably 80 to 110 ° C.

Each component may be coarsely mixed in advance and then placed in a container. Moreover, you may put into a container sequentially.
The container needs to be configured so that it can be stirred. The container can be pressurized by injecting an inert gas such as nitrogen gas. Moreover, you may utilize the raise of the vapor pressure of the solvent by heating. Or after sealing a container, you may add each component under pressure.
When heating, it is preferable to heat from the outside of the container. For example, a jacket type heating device can be used. The entire container can also be heated by providing a plate heater outside the container and piping to circulate the liquid.
It is preferable to provide a stirring blade inside the container and stir using this. The stirring blade preferably has a length that reaches the vicinity of the wall of the container. A scraping blade is preferably provided at the end of the stirring blade in order to renew the liquid film on the vessel wall.
Instruments such as a pressure gauge and a thermometer may be installed in the container. Each component is dissolved in a solvent in a container. The prepared dope is taken out of the container after cooling, or taken out and then cooled using a heat exchanger or the like.

A solution can also be prepared by a cooling dissolution method. In the cooling dissolution method, cellulose acylate can be dissolved in an organic solvent that is difficult to dissolve by a normal dissolution method. In addition, even if it is a solvent which can melt | dissolve a cellulose acylate with a normal melt | dissolution method, there exists an effect that a uniform solution can be obtained rapidly according to a cooling melt | dissolution method. Therefore, the cooling dissolution method is preferably used when dissolving only with a non-chlorine solvent.
In the cooling dissolution method, first, cellulose acylate is gradually added to an organic solvent at room temperature while stirring. The amount of cellulose acylate is preferably adjusted so as to be contained in the mixture in an amount of 10 to 40% by mass. The amount of cellulose acylate is more preferably 10 to 30% by mass. Furthermore, you may add the arbitrary additive mentioned later in a mixture.

Next, the mixture is cooled to −100 to −10 ° C. (−80 to −10 ° C. is more preferable, −50 to −20 ° C. is further preferable, and −50 to −30 ° C. is particularly preferable). The cooling can be performed, for example, in a dry ice / methanol bath (−75 ° C.) or a cooled diethylene glycol solution (−30 to −20 ° C.). The mixture of cellulose acylate and organic solvent is solidified by cooling.
The cooling rate is preferably 4 ° C./min or more, more preferably 8 ° C./min or more, and further preferably 12 ° C./min or more.
The higher the cooling rate, the better. However, 10,000 ° C./second is the theoretical upper limit, 1,000 ° C./second is the technical upper limit, and 100 ° C./second is the practical upper limit. The cooling rate is a value obtained by dividing the difference between the temperature at the start of cooling and the final cooling temperature by the time from the start of cooling to the final cooling temperature.

Furthermore, when this is heated to 0 to 200 ° C. (0 to 150 ° C. is more preferable, 0 to 120 ° C. is more preferable, and 0 to 50 ° C. is particularly preferable), cellulose acylate is dissolved in the organic solvent. The temperature may be increased by simply leaving it at room temperature or in a warm bath.
The heating rate is preferably 4 ° C./min or more, more preferably 8 ° C./min or more, and further preferably 12 ° C./min or more. The higher the heating rate, the better. However, 10,000 ° C./second is the theoretical upper limit, 1,000 ° C./second is the technical upper limit, and 100 ° C./second is the practical upper limit. .
The heating rate is the value obtained by dividing the difference between the temperature at the start of heating and the final heating temperature by the time from the start of heating until the final heating temperature is reached. is there.
A uniform solution is obtained as described above. If the dissolution is insufficient, the cooling and heating operations may be repeated. Whether or not the dissolution is sufficient can be determined by merely observing the appearance of the solution with the naked eye.

In the cooling dissolution method, it is desirable to use a sealed container in order to avoid moisture mixing due to condensation during cooling. In the cooling and heating operation, when the pressure is applied during cooling and the pressure is reduced during heating, the dissolution time can be shortened. In order to perform pressurization and decompression, it is desirable to use a pressure-resistant container.
A 20% by mass solution of cellulose acylate (acetylation degree: 60.9%, viscosity average polymerization degree: 299) dissolved in methyl acetate by the cooling dissolution method is measured by a differential scanning calorimeter (DSC). In addition, there exists a quasi-phase transition point between the sol state and the gel state in the vicinity of 30 ° C., and a uniform gel state is obtained below this temperature. Therefore, it is necessary to keep this solution at a temperature equal to or higher than the pseudo phase transition temperature, preferably about 10 ° C. plus the gel phase transition temperature. However, this pseudo phase transition temperature varies depending on the acyl group substitution degree, the viscosity average polymerization degree, the solution concentration of the cellulose acylate, and the organic solvent used.

[Casting]
A cellulose acylate film is produced from the prepared cellulose acylate solution (dope) by a solvent cast method. It is preferable to add the above-mentioned retardation increasing agent to the dope.
The dope is cast on a drum or band and the solvent is evaporated to form a film. The concentration of the dope before casting is preferably adjusted so that the solid content is 18 to 35%. The surface of the drum or band is preferably finished in a mirror state. The dope is preferably cast on a drum or band having a surface temperature of 10 ° C. or less.

In the present invention, when the dope (cellulose acylate solution) is cast on the band, it is substantially 10 seconds to 90 seconds, preferably 15 seconds to 90 seconds in the first half of the drying before peeling, and substantially no wind. The process of drying is performed.
In the case of casting on a drum, in the first half of drying before peeling, a step of drying in a substantially windless manner for 1 second to 10 seconds, preferably 2 seconds to 5 seconds is performed.
In the present invention, “drying before peeling” refers to drying from when a dope is applied on a band or drum to when it is peeled off as a film.
In addition, the “first half” refers to a process before half of the total time required from dope application to stripping.
Further, “substantially no wind” means that a wind speed of 0.5 m / s or more is not detected at a distance within 200 mm from the band surface or drum surface.
The first half of the pre-peeling drying is usually about 30 to 300 seconds on the band, but is dried for 10 to 90 seconds, preferably 15 to 90 seconds, without wind.
When it is on the drum, it is usually about 5 to 30 seconds, but it is dried without wind for 1 to 10 seconds, preferably 2 to 5 seconds. The ambient temperature is preferably 0 to 180 ° C, more preferably 40 to 150 ° C. The operation of drying without wind can be carried out at any stage in the first half of the drying before peeling, but it is preferably carried out immediately after casting. If the time for drying with no wind is less than 10 seconds, it is difficult for the additive to be uniformly distributed in the film, and if it exceeds 90 seconds, it will be peeled off due to insufficient drying, and the surface condition of the film will deteriorate. .
Drying can be performed by blowing an inert gas during the time other than drying with no wind in drying before peeling. The air temperature at this time is preferably 0 to 180 ° C, more preferably 40 to 150 ° C.

  Regarding the drying method in the solvent cast method, U.S. Pat. Nos. 45-4554, 49-5614, JP-A-60-176834, JP-A-60-203430, and JP-A-62-115035. Drying on the band or drum can be performed by blowing air or an inert gas such as nitrogen.

The obtained film can be peeled off from the drum or band and further dried with high-temperature air whose temperature is successively changed from 100 to 160 ° C. to evaporate the residual solvent. The above method is described in Japanese Patent Publication No. 5-17844.
According to this method, it is possible to shorten the time from casting to stripping. In order to carry out this method, it is necessary for the dope to gel at the surface temperature of the drum or band during casting.

Two or more layers can be cast using the prepared cellulose acylate solution (dope) to form a film. In this case, it is preferable to produce a cellulose acylate film by a solvent cast method.
The dope is cast on a drum or band and the solvent is evaporated to form a film. It is preferable to adjust the concentration of the dope before casting so that the solid content is in the range of 10 to 40%. The surface of the drum or band is preferably finished in a mirror state.

When casting a plurality of cellulose acylate solutions of two or more layers, it is possible to cast a plurality of cellulose acylate solutions, from a plurality of casting openings provided at intervals in the direction of travel of the support. You may produce a film, casting and laminating the solution containing a cellulose acylate, respectively. For example, the methods described in JP-A-61-158414, JP-A-1-122419, and JP-A-11-198285 can be used.
It can also be formed into a film by casting a cellulose acylate solution from two casting ports. For example, JP-B-60-27562, JP-A-61-94724, JP-A-61-947245, JP-A-61-104413, JP-A-61-158413, and JP-A-6-134933. The method described in each publication can be used.
Further, a cellulose acylate film comprising a flow of a high-viscosity cellulose acylate solution described in JP-A-56-162617 is wrapped with a low-viscosity cellulose acylate solution, and the high- and low-viscosity cellulose acylate solution is simultaneously extruded. A casting method can also be used.

Also, using two casting ports, the film formed on the support by the first casting port is peeled off, and the second casting is performed on the side that was in contact with the support surface to produce a film. You can also For example, the method described in Japanese Patent Publication No. 44-20235 can be mentioned.
As the cellulose acylate solution to be cast, the same solution may be used, or different cellulose acylate solutions may be used. In order to give a function to a plurality of cellulose acylate layers, a cellulose acylate solution corresponding to the function may be extruded from each casting port.
Furthermore, the cellulose acylate solution can be cast simultaneously with other functional layers (for example, an adhesive layer, a dye layer, an antistatic layer, an antihalation layer, an ultraviolet absorption layer, a polarizing layer, etc.).

In the conventional single-layer liquid, it is necessary to extrude a cellulose acylate solution having a high concentration and a high viscosity in order to obtain a necessary film thickness. In that case, the stability of the cellulose acylate solution is poor and solid matter is generated, which often causes problems due to defects or poor flatness.
As a solution to this problem, by casting a plurality of cellulose acylate solutions from a casting port, a highly viscous solution can be extruded onto a support at the same time, and the planarity is improved and the film is excellent. Not only can be produced, but also the use of a concentrated cellulose acylate solution can reduce the drying load and increase the production speed of the film.

In order to improve mechanical properties, the following plasticizers can be used for the cellulose acylate film. As the plasticizer, phosphoric acid ester or carboxylic acid ester is used.
Examples of phosphate esters include triphenyl phosphate (TPP) and tricresyl phosphate (TCP).
Representative examples of the carboxylic acid ester include phthalic acid esters and citric acid esters.
Examples of phthalic acid esters include dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), dioctyl phthalate (DOP), diphenyl phthalate (DPP), and diethyl hexyl phthalate (DEHP).
Examples of citrate esters include triethyl O-acetylcitrate (OACTE) and tributyl O-acetylcitrate (OACTB).
Examples of other carboxylic acid esters include butyl oleate, methylacetyl ricinoleate, dibutyl sebacate, and various trimellitic acid esters. Among these, phthalate ester plasticizers (DMP, DEP, DBP, DOP, DPP, DEHP) are preferably used, and DEP and DPP are particularly preferable.
The addition amount of the plasticizer is preferably 0.1 to 25% by mass of the amount of cellulose acylate, more preferably 1 to 20% by mass, and further preferably 3 to 15% by mass.

A degradation inhibitor (eg, antioxidant, peroxide decomposer, radical inhibitor, metal deactivator, acid scavenger, amine) may be added to the cellulose acylate film. The deterioration preventing agents are described in JP-A-3-199201, JP-A-51907073, JP-A-5-194789, JP-A-5-271471, and JP-A-6-107854.
The addition amount of the deterioration preventing agent is preferably 0.01 to 1% by mass of the solution (dope) to be prepared, and more preferably 0.01 to 0.2% by mass. When the addition amount is less than 0.01% by mass, the effect of the deterioration preventing agent is hardly recognized. When the addition amount exceeds 1% by mass, bleed-out (bleeding) of the deterioration preventing agent to the film surface may be observed. Examples of particularly preferred deterioration preventing agents include butylated hydroxytoluene (BHT) and tribenzylamine (TBA).

The steps from casting and stretching to post-drying may be performed in an air atmosphere or an inert gas atmosphere such as nitrogen gas.
The winder used for the production of the cellulose acylate film used in the present invention may be one generally used, such as a constant tension method, a constant torque method, a taper tension method, a program tension control method with a constant internal stress, etc. It can be wound up by a winding method.

[Surface treatment of cellulose acylate film]
The cellulose acylate film is preferably subjected to a surface treatment. Specific examples include corona discharge treatment, glow discharge treatment, flame treatment, acid treatment, alkali treatment, and ultraviolet irradiation treatment. It is also preferable to provide an undercoat layer as described in JP-A-7-333433.
From the viewpoint of maintaining the flatness of the film, in these treatments, the temperature of the cellulose acylate film is preferably Tg (glass transition temperature) or lower, specifically 150 ° C. or lower.
When used as a transparent protective film for a polarizing plate, it is particularly preferable to carry out acid treatment or alkali treatment, that is, saponification treatment for cellulose acylate, from the viewpoint of adhesion to a polarizer.
The surface energy is preferably 55 mN / m or more, and more preferably 60 mN / m or more and 75 mN / m or less.

Hereinafter, the alkali saponification treatment will be specifically described as an example.
The alkali saponification treatment of the cellulose acylate film is preferably performed in a cycle in which the film surface is immersed in an alkali solution, neutralized with an acidic solution, washed with water and dried.
Examples of the alkaline solution include potassium hydroxide solution and sodium hydroxide solution, and the prescribed concentration of hydroxide ions is preferably in the range of 0.1 to 3.0N, and in the range of 0.5 to 2.0N. More preferably. The alkaline solution temperature is preferably in the range of room temperature to 90 ° C, more preferably in the range of 40 to 70 ° C.

The surface energy of a solid can be determined by a contact angle method, a wet heat method, and an adsorption method as described in “Basics and Applications of Wetting” (Realize 1989.12.10). In the case of the cellulose acylate film of the present invention, it is preferable to use a contact angle method.
Specifically, two kinds of solutions having known surface energies are dropped on the cellulose acylate film, and at the intersection between the surface of the droplet and the film surface, the angle formed between the tangent line drawn on the droplet and the film surface, The surface angle of the film can be calculated by defining the angle containing the droplet as the contact angle.

The retardation Re in the in-plane direction of the film can be adjusted by stretching in the transport direction and / or the width direction during film formation and imparting molecular chain orientation of cellulose acylate.
Stretching can be uniaxial stretching or biaxial stretching. Biaxial stretching includes simultaneous biaxial stretching and sequential biaxial stretching, but sequential biaxial stretching is preferred from the viewpoint of continuous production, and after casting the dope, the film is peeled off from the band or drum, After stretching in the width direction (longitudinal method), the film is stretched in the longitudinal direction (width direction).
Methods for stretching in the width direction are described in, for example, JP-A-62-115035, JP-A-4-152125, 4-284221, 4-298310, and 11-48271. Yes. The film is stretched at room temperature or under heating conditions.
The heating temperature is preferably not higher than the glass transition temperature of the film. The film can be stretched by a treatment during drying, and is particularly effective when the solvent remains.
In the case of stretching in the longitudinal direction, for example, the film is stretched by adjusting the speed of the film transport roller so that the film winding speed is higher than the film peeling speed.
In the case of stretching in the width direction, the film can also be stretched by conveying while holding the width of the film with a tenter and gradually widening the width of the tenter.
After the film is dried, it can be stretched using a stretching machine (preferably uniaxial stretching using a long stretching machine).
The stretching ratio of the film (the ratio of the increase due to stretching relative to the original length) is preferably in the range of 5 to 50%, more preferably in the range of 10 to 40%, and in the range of 15 to 35%. Is more preferable. When stretching mainly in the longitudinal direction, the stretching ratio in the longitudinal direction is 10 to 40%, preferably 15 to 35%, and the stretching ratio in the width direction is −20 to 20%, preferably −10 to 10%.
It is also possible to reduce the water permeability by treating the cellulose acylate film at a high temperature to increase the crystallinity. The treatment needs to be performed at such a temperature and time that the volatilization of the low molecular compound and the thermal decomposition of the cellulose acylate film itself are not a problem. The treatment temperature is preferably from 100 ° C. to 260 ° C., more preferably from 140 ° C. to 240 ° C. The treatment time is preferably from 5 minutes to 2 hours, more preferably from 10 minutes to 1 hour.

[Hygroscopic expansion coefficient]
The hygroscopic expansion coefficient indicates the amount of change in the length of the sample when the relative humidity is changed at a constant temperature. In order to prevent frame-like transmittance increase, the hygroscopic expansion coefficient of the cellulose acylate film is preferably 30 × 10 ⁻⁵ /% RH or less, and is preferably 15 × 10 ⁻⁵ /% RH or less. More preferably, it is more preferably 10 × 10 ⁻⁵ /% RH or less. Moreover, although the one where a hygroscopic expansion coefficient is smaller is preferable, it is a value more than 1.0 * 10 < ^-5 > /% RH normally.
The method for measuring the hygroscopic expansion coefficient is shown below. 5 mm wide from the produced polymer film (retardation plate). A sample with a length of 20 mm was cut out, one end was fixed, and the sample was hung in an atmosphere of 25 ° C. and 20% RH (R ₀ ). A weight of 0.5 g was hung from the other end and left for 10 minutes to measure the length (L ₀ ). Next, with the temperature kept at 25 ° C., the humidity was 80% RH (R ₁ ), and the length (L ₁ ) was measured. The hygroscopic expansion coefficient was calculated by the following equation. The measurement was performed 10 samples for the same sample, and the average value was adopted.
Hygroscopic expansion coefficient [/% RH] = {(L ₁ −L ₀ ) / L ₀ } / (R ₁ −R ₀ )

  In order to reduce the dimensional change due to moisture absorption, it is preferable to reduce the amount of residual solvent during film formation to reduce the free volume in the polymer film. A general method for reducing the residual solvent is to dry at a high temperature for a long time. However, if the time is too long, the productivity is naturally lowered. Therefore, the amount of the residual solvent with respect to the cellulose acylate film is preferably in the range of 0.01 to 1% by mass, more preferably in the range of 0.02 to 0.07% by mass, and 0.03 to 0%. More preferably, it is in the range of 0.05 mass%. By controlling the amount of the residual solvent, a polarizing plate having optical compensation ability can be produced at low cost with high productivity.

The amount of residual solvent was measured using a gas chromatograph (GC18A, manufactured by Shimadzu Corporation) after dissolving a certain amount of sample in chloroform. In the solution casting method, a film is produced using a solution (dope) in which a polymer material is dissolved in an organic solvent.
As described later, drying by the solution casting method is largely divided into drying on the drum (or band) surface and drying during film conveyance.
When drying on the drum (or band) surface, it is preferable to dry slowly at a temperature that does not exceed the boiling point of the solvent being used (when the boiling point is exceeded, bubbles are formed).
Moreover, it is preferable to dry at the time of film conveyance at the glass transition point of polymer material ± 30 ° C., more preferably ± 20 ° C.

[Film retardation]
The in-plane retardation value (Re) and thickness direction retardation value (Rth) of the film are defined by the following formulas (I) and (II), respectively.
Re = (nx−ny) × d Expression (I)
Rth = {(nx + ny) / 2−nz} × d (formula (II))
In the formula (I) and the formula (II), nx is a refractive index in the slow axis direction (direction in which the refractive index is maximum) in the film plane.
In the formulas (I) and (II), ny is the refractive index in the fast axis direction (the direction in which the refractive index is minimum) in the film plane.
In formula (II), nz is the refractive index in the thickness direction of the film.
In Formula (I) and Formula (II), d is the thickness of the film whose unit is nm.

  There is no restriction | limiting in particular as said 2nd protective film, According to the objective, it can select suitably, For example, Re is 20-70 nm, Rth is 30-400 nm, Re is 10 nm or less, Rth is Rth It is preferable to use a protective film of 25 nm or less as described later. In order to obtain an optimum retardation value, a retardation film can be laminated on the second protective film.

In addition, it is preferable that the birefringence ((DELTA) n: nx-ny) of a protective film exists in the range of 0.00-0.002 micrometer. Moreover, it is preferable that the birefringence {(nx + ny) / 2−nz} in the thickness direction of the support film and the counter film is in the range of 0.00 to 0.04.
Moreover, the thickness (dry film thickness) of a transparent protective film is 120 micrometers or less, 20-110 micrometers is preferable and 40-100 micrometers is more preferable. The crossing angle between the slow axis of the protective film and the absorption axis of the polarizer may be any value, but is preferably parallel or an azimuth angle of 45 ± 20 °.

[Photoelasticity]
The photoelastic coefficient of the protective film is preferably 60 × 10 ⁻⁸ cm ² / N or less, and more preferably 20 × 10 ⁻⁸ cm ² / N or less. The photoelastic coefficient can be obtained by an ellipsometer.

[Glass-transition temperature]
The glass transition temperature of the protective film is preferably 120 ° C. or higher, and more preferably 140 ° C. or higher. The glass transition temperature is a temperature at which the baseline derived from the glass transition of the film begins to change and a temperature at which the glass returns to the baseline again when measured at a heating rate of 10 ° C./min using a differential scanning calorimeter (DSC). Is obtained as an average value of. The polarizing plate of this invention may have an adhesive layer, a separate film, and a protective film as a component other than the above-mentioned polarizer and protective film.

<Polarizing plate manufacturing process>
Next, the manufacturing process of the polarizing plate of this invention is demonstrated.
The production process of the polarizing plate in the present invention is preferably composed of a swelling process, a dyeing process, a hardening process, a stretching process, a drying process, a protective film bonding process, and a post-bonding drying process. The order of the dyeing step, the hardening step, and the stretching step may be arbitrarily changed, or several steps may be combined and performed simultaneously. Moreover, as described in Japanese Patent No. 3331615, washing with water after the hardening step can be preferably performed.
In the present invention, it is particularly preferable to sequentially perform the swelling process, the dyeing process, the hardening process, the stretching process, the drying process, the protective film bonding process, and the drying process after bonding in the order described. An on-line surface inspection step may be provided during or after the above-described steps.

The swelling step is preferably carried out only with water, but as described in JP-A-10-153709, in order to stabilize optical performance and avoid wrinkling of the polarizing plate substrate in the production line, polarized light is used. It is also possible to manage the degree of swelling of the polarizing plate substrate by swelling the plate substrate with an aqueous boric acid solution.
Moreover, although the temperature and time of a swelling process can be defined arbitrarily, 10 to 60 degreeC and 5 to 2,000 second are preferable.
For the staining step, a method described in JP-A-2002-86554 can be used. Moreover, as a dyeing method, not only immersion but arbitrary means such as application or spraying of iodine or a dye solution are possible. Further, as described in JP-A-2001-290025, a method of dyeing while stirring the concentration of iodine, the dyeing bath temperature, the draw ratio in the bath, and the bath liquid in the bath may be used.
When higher-order iodine ions are used as the dichroic molecule, in order to obtain a high-contrast polarizing plate, it is preferable to use a solution obtained by dissolving iodine in an aqueous potassium iodide solution in the dyeing step. In this case, iodine in the iodine-potassium iodide aqueous solution is preferably 0.05 to 20 g / L, potassium iodide is 3 to 200 g / L, and the mass ratio of iodine and potassium iodide is preferably 1 to 2,000. The dyeing time is preferably 10 to 1,200 seconds, and the liquid temperature is preferably 10 to 60 ° C. More preferably, the iodine is 0.5 to 2 g / L, the potassium iodide is 30 to 120 g / L, the mass ratio of iodine and potassium iodide is 30 to 120, the dyeing time is 30 to 600 seconds, and the liquid temperature is 20-50 degreeC is good. Further, as described in Japanese Patent No. 3145747, boron compounds such as boric acid and borax may be added to the dyeing solution.

In the hardening step, it is preferable to immerse in the crosslinking agent solution or apply the solution to contain the crosslinking agent. Further, as described in JP-A-11-52130, the hardening process can be performed in several steps.
As the cross-linking agent, those described in US Reissue Patent No. 232897 can be used, and as described in Japanese Patent No. 3357109, a polyhydric aldehyde may be used as a cross-linking agent in order to improve dimensional stability. However, boric acids are particularly preferably used. When boric acid is used as the crosslinking agent used in the hardening step, metal ions may be added to the boric acid-potassium iodide aqueous solution. Zinc chloride is preferred as the metal ion, but as described in JP 2000-35512 A, zinc halides such as zinc iodide, zinc sulfates, zinc acetates and the like are used instead of zinc chloride. You can also. In the present invention, it is preferable to prepare a boric acid-potassium iodide aqueous solution to which zinc chloride has been added, and perform dura- tion by immersing the PVA film. Boric acid is preferably 1 to 100 g / L, potassium iodide is 1 to 120 g / L, zinc chloride is preferably 0.01 to 10 g / L, hardening time is preferably 10 to 1,200 seconds, and the liquid temperature is 10 to 60 ° C. Is preferred. More preferably, boric acid is 10 to 80 g / L, potassium iodide is 5 to 100 g / L, zinc chloride is 0.02 to 8 g / L, hardening time is 30 to 600 seconds, and liquid temperature is 20 to 20 g / L. 50 ° C is preferable.

  For the stretching step, a longitudinal uniaxial stretching method as described in US Pat. No. 2,454,515, or a tenter method as described in JP-A-2002-86554 can be preferably used. A preferable draw ratio is 2 times or more and 12 times or less, more preferably 3 times or more and 10 times or less. Further, the relationship between the draw ratio, the thickness of the original fabric and the thickness of the polarizer is described in JP-A No. 2002-040256 (polarizer film thickness after bonding of protective film / raw film thickness) × (total draw ratio) )> 0.17 or the relationship between the width of the polarizer when leaving the final bath and the width of the polarizer when bonding the protective film is 0.80 ≦ (protective film) described in JP-A-2002-040247 The width of the polarizer at the time of bonding / the width of the polarizer at the time of leaving the final bath) ≦ 0.95 can also be preferably set.

  As a drying step, a method known in JP-A-2002-86554 can be used, but a preferable temperature range is 30 to 100 ° C., and a preferable drying time is 30 seconds to 60 minutes. Further, as described in Japanese Patent No. 3148513, heat treatment is performed so that the fading temperature in water is 50 ° C. or higher, or as described in Japanese Patent Application Laid-Open Nos. 07-325215 and 07-325218. Aging in an atmosphere controlled in temperature and humidity is also preferable.

The protective film laminating step is a step of laminating both surfaces of the above-described polarizer that has gone through the drying step with two protective films. A method of bonding with a pair of rolls is preferably used so that the adhesive liquid is supplied immediately before bonding and the polarizer and the protective film are overlapped.
In addition, as described in JP-A-2001-296426 and JP-A-2002-86554, the moisture content of the polarizer at the time of bonding is adjusted in order to suppress the groove-like unevenness of the record due to the stretching of the polarizer. It is preferable to do.
In the present invention, a moisture content of 0.1 to 30% is preferably used. The adhesive between the polarizer and the protective film is not particularly limited, and examples thereof include PVA resins (including modified PVA such as acetoacetyl group, sulfonic acid group, carboxyl group, oxyalkylene group) and boron compound aqueous solution. PVA resin is preferable. The thickness of the adhesive layer is preferably 0.01 to 5 μm, more preferably 0.05 to 3 μm after drying.
Moreover, in order to improve the adhesive force of a polarizer and a protective film, it is preferable to perform adhesion after surface-treating the protective film to make it hydrophilic. The surface treatment method is not particularly limited, and a known method such as a saponification method using an alkaline solution or a corona treatment method can be used.
Further, an easy adhesion layer such as a gelatin undercoat layer may be provided after the surface treatment. As described in JP-A-2002-267839, the contact angle of the protective film surface with water is preferably 50 ° or less. The drying conditions after bonding are in accordance with the method described in JP-A-2002-86554, but the preferable temperature range is 30 to 100 ° C., and the preferable drying time is 30 seconds to 60 minutes. It is also preferable to perform aging in an atmosphere with temperature and humidity control as described in JP-A-07-325220.

Element content in a polarizer is iodine 0.1-3.0 g / m < ² >, boron 0.1-5.0 g / m < ² >, potassium 0.1-2.0 g / m < ² >, zinc 0-2. It is preferably 0 g / m ² .
Further, the potassium content may be 0.2% by mass or less as described in JP-A No. 2001-166143, and the zinc content in the polarizer is described in JP-A No. 2000-035512. It is good also as 0.04-0.5 mass%.
Further, as described in Japanese Patent No. 3323255, in order to increase the dimensional stability of the polarizing plate, at least one of an organic titanium compound and an organic zirconium compound in any of the dyeing process, the stretching process, and the hardening process. Any one of them may be used in addition to contain at least one compound selected from an organic titanium compound and an organic zirconium compound. A dichroic dye may be added to adjust the hue of the polarizing plate.

<Characteristics of polarizing plate>
<< Transmittance and degree of polarization >>
The single plate transmittance of the polarizing plate is preferably 42.5% or more and 49.5% or less, and more preferably 42.8% or more and 49.0% or less.
The range of the degree of polarization defined by the following mathematical formula (1) is preferably 99.900% or more and 99.999% or less, and more preferably 99.940% or more and 99.995% or less.
The range of parallel transmittance is preferably 36% or more and 42% or less, and the range of orthogonal transmittance is preferably 0.001% or more and 0.05% or less.
Furthermore, the range of the dichroic ratio defined by the following mathematical formula (2) is preferably 48 or more and 1215 or less, and more preferably 53 or more and 525 or less.

The iodine concentration and the single plate transmittance may be within the ranges described in JP-A No. 2002-258051.
The parallel transmittance may be small in wavelength dependency as described in JP-A-2001-083328 and JP-A-2002-022950. The optical characteristics when the polarizing plates are arranged in crossed Nicols may be in the range described in Japanese Patent Laid-Open No. 2001-091136, and the relationship between parallel transmittance and orthogonal transmittance is disclosed in Japanese Patent Laid-Open No. 2002-174728. It may be within the range described.
As described in Japanese Patent Application Laid-Open No. 2002-221618, the standard deviation of the parallel transmittance every 10 nm when the light wavelength is between 420 and 700 nm is 3 or less, and the light wavelength is between 420 and 700 nm. The minimum value of (parallel transmittance / orthogonal transmittance) every 10 nm may be 300 or more.
The parallel transmittance and orthogonal transmittance at a wavelength of 440 nm of the polarizing plate, the parallel transmittance, the parallel transmittance and the orthogonal transmittance at a wavelength of 550 nm, and the parallel transmittance and the orthogonal transmittance at a wavelength of 610 nm are disclosed in JP-A No. 2002-258042 and JP-A No. 2002-80442. The range described in 2002-258043 can also be preferably performed.

<< Durability >>
[Damp heat durability]
As described in JP-A No. 2001-116922, when the light transmittance and the degree of polarization change before and after leaving in an atmosphere of 60 ° C. and 90% RH for 500 hours are 3% or less based on absolute values Preferably there is. In particular, the change rate of the light transmittance is preferably 2% or less, and the change rate of the polarization degree is preferably 0.5% or less, more preferably 0.2% or less based on the absolute value. Further, as described in JP-A-07-0777608, it is also preferable that the degree of polarization after standing at 80 ° C., 90% RH and 500 hours is 95% or more and the single transmittance is 38% or more.
(2-2) Dry durability It is preferable that the light transmittance and the change rate of the polarization degree before and after leaving for 500 hours in a dry atmosphere at 80 ° C. are also 3% or less based on absolute values. In particular, the change rate of the light transmittance is preferably 2% or less, and the change rate of the polarization degree is preferably 0.5% or less, more preferably 0.2% or less based on the absolute value.

[Other durability]
Furthermore, as described in JP-A-06-167611, 69 is a polarizing plate laminate in which the shrinkage ratio after standing at 80 ° C. for 2 hours is 0.5% or less, or crossed Nicols are arranged on both surfaces of a glass plate. The x and y values after leaving for 750 hours in an atmosphere of ℃ are within the range described in JP-A-10-068818, or Raman after being left for 200 hours in an atmosphere of 80 ° C. and 90% RH 105 cm ^-1 by spectroscopy, and the change in spectral intensity ratio of 157cm ^-1, can be preferably in the range described in JP-a-08-094834 and JP-a-09-197127.

<< degree of orientation >>
The higher the degree of orientation of PVA, the better the polarization performance. However, the order parameter value calculated by means such as polarized Raman scattering or polarized FT-IR is preferably 0.2 to 1.0.
Also, as described in JP-A-59-133509, the difference between the orientation coefficient of the polymer segment in the entire amorphous region of the polarizer and the orientation coefficient of the occupied molecule (0.75 or more) is at least 0. 15, the orientation coefficient of the amorphous region of the polarizer is 0.65 to 0.85, as described in JP-A No. 04-204907, and the higher iodine ions of I ₃ ⁻ and I ₅ ⁻ It is also preferable to set the degree of orientation to 0.8 to 1.0 as an order parameter value.

<< Other characteristics >>
As described in JP-A No. 2002-006133, the contraction force in the absorption axis direction per unit width when heated at 80 ° C. for 30 minutes is 4.0 N / cm or less, or described in JP-A No. 2002-236213. As shown in the figure, when the polarizing plate is placed under heating at 70 ° C. for 120 hours, the dimensional change rate in the absorption axis direction and the dimensional change rate in the polarization axis direction of the polarizing plate are both within ± 0.6%. Or the moisture content of the polarizing plate is preferably 3% by mass or less as described in JP-A-2002-090546. Further, as described in JP-A No. 2000-249832, the surface roughness in the direction perpendicular to the stretching axis is set to 0.04 μm or less based on the center line average roughness, or described in JP-A No. 10-268294. The refractive index n ₀ in the transmission axis direction is preferably made larger than 1.6, or the relationship between the thickness of the polarizing plate and the thickness of the protective film is preferably within the range described in JP-A-10-111411. be able to.

<Functionalization of polarizing plate>
The polarizing plate includes an LCD viewing angle widening film, a λ / 4 plate for application to a reflective LCD, an antireflection film for improving display visibility, a brightness enhancement film, a hard coat layer, a forward scattering layer, It is preferably used as a functionalized polarizing plate combined with an optical film having a functional layer such as an antiglare (antiglare) layer.
A configuration example in which the polarizing plate and the functional optical film described above are combined is shown in FIG. A functional optical film and a polarizer may be bonded via an adhesive as a protective film on one side of the polarizing plate (see FIG. 1A), or an adhesive is applied to the polarizing plate provided with protective films on both sides of the polarizer. A functional optical film may be adhered via the substrate (see FIG. 1B). In the former case, any transparent protective film can be used for the other protective film. The peel strength between layers such as the functional layer and the protective film is preferably 4.0 N / 25 mm or more described in JP-A No. 2002-311238. The functional optical film is preferably arranged on the liquid crystal module side according to the intended function, or on the side opposite to the liquid crystal module, that is, on the display side or the backlight side.
In FIGS. 1A and 1B, 1, 1a and 1b are protective films, 2 is a polarizer, 3 is a functional optical film, and 4 is an adhesive layer.

The functional optical film used in combination with the polarizing plate of the present invention will be described below.
<< Viewing angle expansion film >>
The polarizing plate includes TN (Twisted Nematic), IPS (In-Plane Switching), OCB (Optically Compensated Bend), VA (Vertically Aligned), ECB (Electrically Controlled View). Can be used in combination with a magnifying film. Among these, when the polarizing plate of the present invention is applied to the VA mode and the IPS mode, the color change due to temperature and humidity is small, and higher display quality can be obtained.

[TN mode]
By applying the polarizing plate to a TN mode liquid crystal display device as follows, a liquid crystal display device with high display quality can be provided without causing problems such as light leakage. As the viewing angle widening film for the TN mode, Journal of the Japan Printing Society, Vol. 36, No. 3 (1999), p. 75115, JP-A-6-214116, JP-A-8-50206, etc. are preferably used in combination with WV film (manufactured by Fuji Film Co., Ltd.). A preferred configuration of the viewing angle widening film for the TN mode has an alignment layer and an optically anisotropic layer in this order on a transparent support. Although a viewing angle expansion film may be used by being bonded to a polarizing plate via an adhesive, SID'00Dig. , P551 (2000), it is particularly preferable from the viewpoint of thinning that it is used also as one of the protective films of the polarizer.

The alignment layer can be provided by means such as a rubbing treatment of an organic compound (preferably a polymer), oblique deposition of an inorganic compound, or formation of a layer having a microgroup.
Furthermore, an alignment layer in which an alignment function is generated by application of an electric field, application of a magnetic field, or light irradiation is also known, but an alignment layer formed by a rubbing treatment of a polymer is particularly preferable. The rubbing treatment is preferably performed by rubbing the surface of the polymer layer several times in a certain direction with paper or cloth. It is preferable that the absorption axis direction and the rubbing direction of the polarizer are substantially parallel. As the polymer used for the alignment layer, polyimide, polyvinyl alcohol, a polymer having a polymerizable group described in JP-A-9-152509, and the like can be preferably used. The thickness of the alignment layer is preferably 0.01 to 5 μm, and more preferably 0.05 to 2 μm.
The optically anisotropic layer preferably contains a liquid crystal compound. The liquid crystal compound used in the present invention particularly preferably has a discotic compound (discotic liquid crystal). The discotic liquid crystal molecules have a disk-like core portion like a triphenylene derivative represented by the following general formula (D-1), and have a structure in which side chains extend radially therefrom.
Further, in order to impart stability over time, it is also preferable to further introduce a group that reacts with heat, light or the like. Preferred examples of the discotic liquid crystal are described in JP-A-8-50206.

The discotic liquid crystal molecules are aligned almost parallel to the film plane with a pretilt angle in the rubbing direction in the vicinity of the alignment layer, and the discotic liquid crystal molecules are oriented so that they are perpendicular to the plane on the opposite air side. is doing. The discotic liquid crystal layer as a whole has a hybrid alignment, and this layer structure can realize a wide viewing angle of a TN mode TFT-LCD.
The optically anisotropic layer is generally formed by applying a solution obtained by dissolving a discotic compound and another compound (for example, a polymerizable monomer, a photopolymerization initiator) in a solvent onto the alignment layer, drying, and then discotic nematic. After heating to the phase formation temperature, it is obtained by polymerizing by irradiation with UV light or the like and further cooling. The discotic nematic liquid crystal phase-solid phase transition temperature of the discotic liquid crystalline compound used in the present invention is preferably 70 to 300 ° C, more preferably 70 to 170 ° C.

  In addition to the discotic compound added to the optically anisotropic layer, the compound has compatibility with the discotic compound and can give a preferable change in tilt angle to the liquid crystalline discotic compound or inhibit the alignment. Any compound can be used as long as it is not. Among these, additives for controlling the orientation on the air interface side such as polymerizable monomers (eg, compounds having vinyl group, vinyloxy group, acryloyl group and methacryloyl group), fluorine-containing triazine compounds, cellulose acetate, cellulose acetate Polymers such as pionate, hydroxypropylcellulose, and cellulose acetate butyrate are listed. These compounds are generally used in an amount of 0.1 to 50% by mass, preferably 0.1 to 30% by mass, based on the discotic compound. The thickness of the optically anisotropic layer is preferably 0.1 to 10 μm, and more preferably 0.5 to 5 μm. The Re of the optically anisotropic layer is preferably 10 to 100 nm, more preferably 20 to 70 nm, and still more preferably 30 to 50 nm. Under the present circumstances, the range of 0-50 nm is preferable and, as for the front retardation value Re of the cellulose acylate base to be used, 2-30 nm is more preferable. The retardation value Rth in the film thickness direction is preferably in the range of 10 to 200 nm, and more preferably 30 to 150 nm.

A preferred embodiment of the viewing angle widening film is composed of a cellulose acylate film as a transparent substrate film, an alignment layer provided thereon, and an optically anisotropic layer comprising a discotic liquid crystal formed on the alignment layer. And the optically anisotropic layer is crosslinked by UV light irradiation.
In addition to the above, when the viewing angle widening film and the polarizing plate of the present invention are combined, for example, as described in JP-A-07-198942, a compound having an optical axis in a direction intersecting the plate surface is used. It is also preferable to laminate with a phase difference plate exhibiting anisotropy in refraction, or to make the dimensional change rate of the protective film and the optically anisotropic layer substantially the same as described in JP-A No. 2002-258052. It can be carried out.
Further, as described in JP-A No. 2000-258632, the moisture content of the polarizing plate bonded to the viewing angle widening film is set to 2.4% or less, or as described in JP-A No. 2002-267839. Further, the contact angle with water on the surface of the viewing angle widening film can be preferably set to 70 ° or less.

[OCB mode]
The polarizing plate can provide a liquid crystal display device with high display quality without causing problems such as light leakage even when applied to an OCB mode liquid crystal display device as described below.
The OCB mode is sometimes called a bend mode or a pi-cell mode because of the alignment state of liquid crystal molecules. The liquid crystal alignment state changes greatly when no electric field is applied, when an OFF electric field is applied, and when an ON electric field is applied. The alignment state of the liquid crystal molecules in the liquid crystal cell when an electric field is applied has a relationship of self-mutual optical compensation, and the viewing angle is wide. Also, the response speed is faster than other display modes. The problem is that since black display is performed in the ON state, the arrangement of the optical compensation layer is essential.
The OCB mode viewing angle widening film for liquid crystal cells is intended to improve the viewing angle characteristics of black display by optically compensating the liquid crystal layer that is vertically aligned at the center of the liquid crystal layer by applying an electric field and tilted near the substrate interface. used.
When the polarizing plate is used in an OCB mode liquid crystal cell, it is preferably used in combination with a viewing angle widening film in which a discotic liquid crystalline compound as described in US Pat. No. 5,805,253 is hybrid-aligned.
In this case, the front retardation value Re (unit: nm) of the cellulose acylate base used is preferably in the range of 10 to 100 nm, more preferably 20 to 70 nm. The retardation value Rth (unit: nm) in the film thickness direction is preferably in the range of 50 to 300 nm, more preferably 100 to 250 nm. Moreover, 10-100 nm is preferable, as for Re of the optically anisotropic layer provided on a 2nd protective film, 20-70 nm is more preferable, and 25-40 nm is still more preferable.

[ECB mode]
The polarizing plate can provide a liquid crystal display device with high display quality without causing problems such as light leakage even when applied to an ECB mode liquid crystal display device as described below.
When used in a transflective liquid crystal display, an optical compensation film that produces circularly polarized light is often used. In this case, a so-called λ / 4 plate having an in-plane retardation of ¼ of the wavelength of light is suitable as the optical compensation film. In order to satisfy this condition in the entire visible light region, there is an example in which the slow axes of the optical compensation film having a retardation of λ / 4 and the optical compensation film of a λ / 2 plate are crossed (see Japanese Patent No. 3236304). ).
The polarizing plate can be used as a circular polarizing plate laminated with a λ / 4 plate.
The λ / 4 plate used in the present invention is a retardation film having a retardation (Re) of approximately ¼ of the wavelength in the visible light wavelength range in order to obtain almost perfect circularly polarized light in the visible light wavelength range. It is preferable that
“Retardation of approximately ¼ in the wavelength range of visible light” means that the longer the wavelength is from 400 to 700 nm, the larger the retardation, and the retardation value (Re450) measured at a wavelength of 450 nm is 80 to 125 nm. And the range which satisfies the relationship whose retardation value (Re590) measured by wavelength 590nm is 120-160 nm is shown. Re590-Re450 ≧ 5 nm is preferable, and Re590-Re450 ≧ 10 nm is more preferable.
The λ / 4 plate used in the present invention is not particularly limited as long as the above conditions are satisfied. For example, in Japanese Patent Laid-Open Nos. 5-27118, 10-68816, and 10-90521 Lambda / 4 plate in which a plurality of polymer films described above are laminated, Lambda / 4 plate obtained by stretching one polymer film described in WO00 / 65384, WO00 / 26705, JP 2000-284126 A A known λ / 4 plate such as a λ / 4 plate in which at least one optically anisotropic layer is provided on a polymer film described in JP-A-2002-31717 can be used. Moreover, the direction of the slow axis of the polymer film and the orientation direction of the optically anisotropic layer can be arranged in any direction according to the liquid crystal cell.

In the circularly polarizing plate, the slow axis of the λ / 4 plate and the transmission axis of the polarizer can intersect at an arbitrary angle, but preferably intersect within a range of 45 ° ± 20 °. However, the slow axis of the λ / 4 plate and the transmission axis of the polarizer may intersect within a range other than the above.
When the λ / 4 plate is configured by laminating the λ / 4 plate and the λ / 2 plate, as described in Japanese Patent No. 3236304 and Japanese Patent Laid-Open No. 10-68816, the λ / 4 plate and Bonding is preferably performed so that the angle formed by the slow axis in the plane of the λ / 2 plate and the transmission axis of the polarizing plate is substantially 75 ° and 15 °.

  When used as a transmissive liquid crystal display device, it is preferably used in combination with a viewing angle widening film in which a discotic liquid crystal compound is hybrid-aligned. In this case, Re based on cellulose is preferably 0 to 300 nm, and more preferably 0 to 200 nm. Rth is preferably 0 to 200 nm, and more preferably 0 to 100 nm. 10-100 nm is preferable and, as for Re of an optically anisotropic layer, 10-50 nm is more preferable.

[VA mode]
When the polarizing plate is applied to a VA mode liquid crystal display device as described below, a liquid crystal display device with high display quality can be provided without causing problems such as light leakage.
The VA mode liquid crystal cell optical compensation film improves the viewing angle characteristics of black display in a state in which liquid crystal molecules are vertically aligned with respect to the substrate surface when no electric field is applied.
As such an optical compensation film, a sheet having an in-plane retardation close to 0 and having a retardation in the thickness direction is suitable (Japanese Patent No. 2866372). The liquid crystal molecules are rod-like and vertically aligned, and a disk-like compound is preferably arranged parallel to the substrate for optical compensation. There are examples in which stretched films having the same in-plane retardation value are laminated so that the slow axes are orthogonal to each other, or a disk-like liquid crystalline compound is formed by coating. Furthermore, there is an example in which sheets made of rod-like compounds such as liquid crystal molecules are laminated in order to prevent deterioration of the orthogonal transmittance in the oblique direction of the polarizing plate.
And a polarizing plate is comprised as what laminated | stacked the said polarizing plate protective film on the at least single side | surface side of a polarizer. A VA liquid crystal display device is obtained by providing the polarizing plate thus obtained on one or both sides of a VA (Virtual Alignment) liquid crystal cell.

The second protective film used for the polarizing plate can itself be used as an optically anisotropic film. In this case, the front retardation value Re (unit: nm) is in the range of 20 to 100 nm. Preferably, 30 to 70 nm is more preferable.
The thickness direction retardation value Rth (unit: nm) is preferably 50 to 250 nm, and more preferably 80 to 170 nm.
By using a polarizing plate using an optical film having a thickness direction retardation value (Rth value) in the above range as a polarizing plate protective film, good viewing angle characteristics in a VA liquid crystal display device can be obtained. .
In addition to the second protective film having the optical anisotropy, an arbitrary retardation film can be used between the polarizing plate and the liquid crystal cell. Although not particularly limited, a retardation film formed from a stretched norbornene-based resin film, a polycarbonate-based resin film, or a resin film of polyamide, polyester, or the like can be used.
The above combination is not particularly limited, but a representative combination for obtaining good viewing angle characteristics when realizing optical anisotropy only with the second protective film is the second polarization As the plate protective film, a cellulose acylate film having a thickness of 40 to 100 μm and an acyl substitution degree SA + SB of 2.30 ≦ SA + SB <2.80 and 0 ≦ SB ≦ 1.00 is stretched by 10 to 35% by the above-described method. There is a method in which a polarizing plate having a retardation plate made of cellulose acylate having desired optical characteristics is prepared and bonded to at least one side of a VA mode liquid crystal cell via an adhesive. Among them, a polarizing plate having a second polarizing plate protective film obtained by stretching a cellulose acylate film having an acyl substitution degree of SA + SB of 2.30 ≦ SA + SB <2.60 and 0.50 <SB <0.80 is obtained. A method of laminating on both sides, using a polarizing plate having a second protective film obtained by stretching a cellulose acylate film having an acyl substitution degree of SA + SB of 2.30 ≦ SA + SB <3.00 and SB = 0 on the backlight side of the cell. There are ways to compensate.

  Moreover, as a method of using a retardation plate other than the second protective film, between the VA mode liquid crystal cell and the polarizing plate, polyamide, polyimide, polyester, poly (ether ketone), poly (amide imide) and poly (ester imide) are used. A retardation thin film satisfying a relationship of nx> ny> nz, where nx and ny are refractive indexes in two directions in the plane, and nz is a refractive index in the thickness direction. There are also known methods for compensating by providing the above.

[IPS mode]
When the polarizing plate is applied to an IPS mode liquid crystal display device as described below, a liquid crystal display device with high display quality can be provided without causing problems such as light leakage.
The viewing angle widening film for an IPS mode liquid crystal cell is used for optical compensation of liquid crystal molecules aligned in parallel to the substrate surface and improvement of viewing angle characteristics of the orthogonal transmittance of the polarizing plate during black display in the absence of an electric field.
In the IPS mode, black is displayed when no electric field is applied, and the transmission axes of the pair of upper and lower polarizing plates are orthogonal.
However, when observed from an oblique direction, the crossing angle of the transmission axes is not 90 °, and leakage light is generated and the contrast is lowered.
When the polarizing plate is used in an IPS mode liquid crystal cell, the in-plane retardation as described in JP-A-10-54982 is close to 0 and the retardation in the thickness direction is reduced in order to reduce leakage light. It is preferably used in combination with a viewing angle widening film having
For example, a polarizing plate having a cellulose acylate film having Re of 0 to 100 nm and Rth of 0 to 200 nm as a second protective film, and a retardation of Re of 50 to 300 nm and Rth of 0 to 200 nm When a plate is used in combination, or a polarizing plate having a second protective film in which an optically anisotropic layer is provided on a cellulose acylate film having Re of 0 to 100 nm and Rth of 0 to 200 nm, Re is 50. The case where it uses in combination with a phase difference plate of -300 nm and Rth of 0-200 nm, etc. is mentioned.

Further, the polarizing plate used for optical compensation of the IPS mode liquid crystal display device is not limited to the following, but a retardation film having a maximum refractive index in the film thickness direction can also be suitably used in combination.
By the means as described above, the cellulose acylate film can be used as the second protective film for the polarizing plate by imparting a characteristic that maximizes the refractive index in the film thickness direction.
Although the preferable optical characteristics of the film having the maximum refractive index in the film thickness direction depend on the characteristics of the retardation film to be combined, those having the following characteristics are preferably used. For example, Re is preferably 0 to 50 nm, and more preferably 0 to 10 nm. On the other hand, Rth is preferably -20 to -300 nm, and more preferably -80 to -160 nm.

Further, the polarizing plate used for optical compensation of the IPS mode liquid crystal display device is not limited to the following, but has an additive for reducing the optical anisotropy of the cellulose acylate film, and has a front retardation. | Re | ≦ 10, a polarizing plate including a second protective film having a retardation in the thickness direction of | Rth | ≦ 25, and an acyl substitution degree SA + SB of 2.30 ≦ SA + SB <3.00, 0 ≦ SB <1. 00, a polarizing plate having a second protective film made of a cellulose acylate film having a film thickness of 40 to 80 μm, or a polarizing plate having a second protective film in which the cellulose acylate film is stretched and has optical anisotropy, etc. Can be suitably used.
Moreover, these polarizing plates can also be used in combination with a norbornene-based resin, a polycarbonate-based resin, or a retardation film obtained by coating a liquid crystalline compound on these resins.
As a specific example, a polarizing plate using Z-TAC (manufactured by FUJIFILM Corporation) as a second protective film is bonded to the backlight side of the cell, and the second protection is provided to the viewer side. As the film, 2.30 ≦ SA + SB <2.50, 0.80 <SB <1.00, a cellulose acylate film having a film thickness of 40 μm, or a cellulose acylate film having a maximum refractive index in the film thickness direction. Examples include using a polarizing plate and providing a stretched norbornene-based film or a polycarbonate-based film between the polarizing plate and the liquid crystal cell.
Further, on the backlight side of the cell, as a second protective film, a polarizing plate having a cellulose acylate film having a thickness of 2.30 ≦ SA + SB <2.50, 0.80 <SB <1.00, and a film thickness of 40 μm And a liquid crystal cell, a norbornene-based film having a thickness of 80 to 100 μm is stretched, a retardation plate having Re of 100 to 250 nm and Rth of 50 to 150 nm is provided, and on the viewer side, as a second protective film 2.30 ≦ SA + SB <2.50, 0.80 <SB <1.00, and between a polarizing plate having a cellulose acylate film having a thickness of 40 μm and a liquid crystal cell, the thickness is 50 to 100 μm and the Re is 200 There is a compensation method in which a stretched polycarbonate phase difference plate having a thickness of ˜300 nm and an Rth of 0 to 50 nm is provided.

<< Antireflection Film >>
The polarizing plate can be used in combination with an antireflection film.
For the anti-reflection film, either a film having a reflectance of about 1.5% only by applying a single layer of a low refractive index material such as a fluorine-based polymer, or a film having a reflectance of 1% or less using multilayer interference of a thin film is used. it can.
In the present invention, a structure in which a low refractive index layer and at least one layer having a higher refractive index than that of the low refractive index layer (that is, a high refractive index layer and a middle refractive index layer) is laminated on a transparent support is preferably used. The
In addition, Nitto Technical Report, vol. 38, no. 1, May, 2000, pages 26 to 28, JP-A-2002-301783, and the like can also be preferably used. The refractive index of each layer satisfies the following relationship.
The refractive index of the high refractive index layer> the refractive index of the medium refractive index layer> the refractive index of the transparent support> the transparent support used for the refractive index antireflection film of the low refractive index layer is used for the protective film of the polarizing layer described above. A transparent polymer film can be preferably used.

The refractive index of the low refractive index layer is preferably 1.20 to 1.55, more preferably 1.30 to 1.50.
The low refractive index layer is preferably used as an outermost layer having scratch resistance and antifouling properties. In order to improve the scratch resistance, it is also preferable to impart slipperiness to the surface using a material containing a silicone group or fluorine.
Examples of the fluorine-containing compound include paragraph numbers [0018] to [0026] of JP-A-9-222503, paragraph numbers [0019] to [0030] of JP-A-11-38202, and JP-A-2001-40284. The compounds described in paragraph Nos. [0027] to [0028], JP-A No. 2000-284102 and the like can be preferably used.
The silicone-containing compound is preferably a compound having a polysiloxane structure, but reactive silicone (eg, Silaplane (manufactured by Chisso Corporation), polysiloxane containing silanol groups at both ends (Japanese Patent Laid-Open No. 11-258403), etc. Alternatively, an organometallic compound such as a silane coupling agent and a specific fluorine-containing hydrocarbon group-containing silane coupling agent may be cured by a condensation reaction in the presence of a catalyst (Japanese Patent Laid-Open No. 58-86). 142958, 58-147483, 58-147484, JP-A-9-157582, 11-106704, JP-A-2000-117902, 2001-48590, 2002 -53804 publication etc.).
The low refractive index layer has an average primary particle diameter of 1 to 150 nm such as fillers (for example, silicon dioxide (silica), fluorine-containing particles (magnesium fluoride, calcium fluoride, barium fluoride)) as additives other than the above. And a low refractive index inorganic compound, organic fine particles described in paragraphs [0020] to [0038] of JP-A No. 11-3820), silane coupling agents, slip agents, surfactants, and the like are also preferably included. be able to.

The low refractive index layer may be formed by a vapor phase method (vacuum deposition method, sputtering method, ion plating method, plasma CVD method, etc.), but is preferably formed by a coating method because it can be manufactured at low cost. .
As the coating method, dip coating, air knife coating, curtain coating, roller coating, wire bar coating, gravure coating, and micro gravure can be preferably used.
The film thickness of the low refractive index layer is preferably 30 to 200 nm, more preferably 50 to 150 nm, and still more preferably 60 to 120 nm.
The medium refractive index layer and the high refractive index layer preferably have a structure in which ultrafine particles of high refractive index having an average particle diameter of 100 nm or less are dispersed in a matrix material.
Inorganic compound fine particles having a high refractive index include inorganic compounds having a refractive index of 1.65 or more, for example, oxides such as Ti, Zn, Sb, Sn, Zr, Ce, Ta, La, and In, and metal atoms thereof. A composite oxide or the like can be preferably used.
Such ultrafine particles may be obtained by treating the surface of the particles with a surface treatment agent (silane coupling agent, etc .: JP-A Nos. 11-295503, 11-153703, 2000-9908, anionic compounds or (Organic metal coupling agent: JP-A No. 2001-310432, etc.), core-shell structure with a high refractive index particle as a core (JP-A No. 2001-166104, etc.), or a specific dispersant (eg, JP-A No. 11- No. 153703, Patent No. US62010858B1, Japanese Patent Laid-Open No. 2002-27776069, etc.).
As the matrix material, conventionally known thermoplastic resins, curable resin films, and the like can be used, but JP-A 2000-47004, 2001-315242, 2001-31871, 2001-296401. It is also possible to use a curable film obtained from a polyfunctional material described in a gazette or the like or a metal alkoxide composition described in JP-A-2001-293818 or the like.

The refractive index of the high refractive index layer is preferably 1.70 to 2.20. The thickness of the high refractive index layer is preferably 5 nm to 10 μm, and more preferably 10 nm to 1 μm.
The refractive index of the middle refractive index layer is adjusted to be a value between the refractive index of the low refractive index layer and the refractive index of the high refractive index layer. The refractive index of the middle refractive index layer is preferably 1.50 to 1.70.
The haze of the antireflection film is preferably 5% or less, more preferably 3% or less. The film strength is preferably H or higher, more preferably 2H or higher, and further preferably 3H or higher, in a pencil hardness test according to JIS K5400.

<< Brightness enhancement film >>
The polarizing plate can be used in combination with a brightness enhancement film. The brightness enhancement film has a function of separating circularly polarized light or linearly polarized light, and is disposed between the polarizing plate and the backlight, and reflects or backscatters one circularly polarized light or linearly polarized light to the backlight side.
The re-reflected light from the backlight part partially changes the polarization state and partially transmits when it re-enters the brightness enhancement film and the polarizing plate. By repeating this process, the light utilization rate is improved. The front luminance is improved to about 1.4 times.
As the brightness enhancement film, an anisotropic reflection method and an anisotropic scattering method are known, and both can be combined with the polarizing plate of the present invention.

In the anisotropic reflection system, a brightness enhancement film having anisotropy in reflectance and transmittance is known by laminating a uniaxially stretched film and an unstretched film in multiple layers and increasing the refractive index difference in the stretching direction. Multilayer film systems using the principle of dielectric mirrors (described in the specifications of WO95 / 17691, WO95 / 17692, WO95 / 17699) and cholesteric liquid crystal systems (European Patent No. 606940A2, Japanese Patent Laid-Open No. Hei 8- No. 271731) is known.
DBEF-E, DBEF-D, and DBEF-M (all manufactured by 3M) are used as multilayer-type brightness enhancement films using the principle of dielectric mirrors, and NIPOCS (Nitto Denko ( Co.) is preferably used in the present invention. For NIPOCS, see Nitto Giho, vol. 38, no. 1, may, 2000, pages 19 to 21 and the like.

Further, in the present invention, each of the specifications described in WO97 / 32223, WO97 / 32224, WO97 / 32225, WO97 / 32226 and JP-A-9-274108 and 11-174231 It is also preferable to use a combination of the intrinsic birefringent polymer and the negative intrinsic birefringent polymer in combination with a uniaxially stretched anisotropic scattering type brightness enhancement film.
As the anisotropic scattering system brightness enhancement film, DRPF-H (manufactured by 3M) is preferable. The polarizing plate and the brightness enhancement film of the present invention are preferably used as an integrated type in which one of the protective film of the polarizing plate and the protective film of the polarizing plate is bonded via an adhesive.

<< Other functional optical films >>
The polarizing plate is used in combination with a functional optical film further provided with a hard coat layer, a forward scattering layer, an antiglare (antiglare) layer, a gas barrier layer, a sliding layer, an antistatic layer, an undercoat layer, a protective layer and the like. It is also preferable to do. These functional layers are also preferably used in combination in the same layer as the above-described antireflection layer and optically anisotropic layer.

[Hard coat layer]
In order to impart mechanical strength such as scratch resistance to the polarizing plate, it is preferable to combine a hard coat layer with a functional optical film provided on the surface of the transparent support. When the hard coat layer is applied to the above-described antireflection film, it is particularly preferable to provide it between the transparent support and the high refractive index layer.
The hard coat layer is preferably formed by a crosslinking reaction or a polymerization reaction of the curable compound by at least one of light and heat. The curable functional group is preferably a photopolymerizable functional group, and the hydrous functional group-containing organometallic compound is preferably an organic alkoxysilyl compound.
As specific constituent compositions of the hard coat layer, for example, those described in JP-A Nos. 2002-144913, 2000-9908 and WO00 / 46617 can be preferably used.
The film thickness of the hard coat layer is preferably 0.2 to 100 μm.
The strength of the hard coat layer is preferably H or higher, more preferably 2H or higher, and still more preferably 3H or higher, in a pencil hardness test according to JIS K5400. Moreover, in the Taber test according to JISK5400, the smaller the amount of wear of the test piece before and after the test, the better.

As the material for forming the hard coat layer, a compound containing an ethylenically unsaturated group or a compound containing a ring-opening polymerizable group can be used, and these compounds can be used alone or in combination.
Preferred examples of the compound containing an ethylenically unsaturated group include ethylene glycol diacrylate, trimethylolpropane triacrylate, ditrimethylolpropane tetraacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol. Polyacrylates of polyols such as hexaacrylate; epoxy acrylates such as diacrylate of bisphenol A diglycidyl ether, diacrylate of hexanediol diglycidyl ether; obtained by reaction of polyisocyanate and hydroxyl group-containing acrylate such as hydroxyethyl acrylate Examples of preferred compounds include urethane acrylates.
Moreover, as a commercially available compound, EB-600, EB-40, EB-140, EB-1150, EB-1290K, IRR214, EB-2220, TMPTA, TMPTMA (above, Daicel UCB Co., Ltd. product), UV -6300, UV-1700B (manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) and the like.

Preferred examples of the compound containing a ring-opening polymerizable group include ethylene glycol diglycidyl ether, bisphenol A diglycidyl ether, trimethylol ethane triglycidyl ether, trimethylol propane triglycidyl ether, glycerol triglycidyl ether as glycidyl ethers. Triglycidyl trishydroxyethyl isocyanurate, sorbitol tetraglycidyl ether, pentaerythritol tetraglycyl ether, polyglycidyl ether of cresol novolac resin, polyglycidyl ether of phenol novolac resin, etc. Celoxide 2021P, Celoxide 2081, Epoxide GT-301, Epolide GT-401, EHPE3150CE (above, IXETA 121, OXT-221, OX-SQ, PNOX-1009 (above, manufactured by Toagosei Co., Ltd.) and the like as oxetanes such as polyisocyanate epoxy methyl ether of phenolic novolak resin) Can be mentioned.
In addition, a polymer of glycidyl (meth) acrylate or a copolymer of a monomer that can be copolymerized with glycidyl (meth) acrylate may be used for the hard coat layer.

In the hard coat layer, fine particles of oxide such as silicon, titanium, zirconium, and aluminum are used to reduce curing shrinkage of the hard coat layer, improve adhesion to the base material, and reduce curling of the hard coat treated article of the present invention. It is also preferable to add crosslinked fine particles such as crosslinked fine particles such as polyethylene, polystyrene, poly (meth) acrylic acid esters, polydimethylsiloxane and the like, and fine organic particles such as fine crosslinked rubber fine particles such as SBR and NBR.
The average particle size of these crosslinked fine particles is preferably 1 to 20,000 nm. The shape of the crosslinked fine particles can be used without particular limitation, such as a spherical shape, a rod shape, a needle shape, or a plate shape. The addition amount of the fine particles is preferably 60% by volume or less, more preferably 40% by volume or less of the hard coat layer after curing.
In the case of adding the oxide fine particles described above, since the affinity with the binder polymer is generally poor, it contains a metal such as silicon, aluminum, titanium, and the alkoxide group, carboxylic acid group, sulfonic acid group, phosphonic acid group. It is also preferable to perform a surface treatment using a surface treatment agent having a functional group such as.
The hard coat layer is preferably cured using heat or active energy rays, and among them, it is more preferred to use active energy rays such as radiation, gamma rays, alpha rays, electron rays, ultraviolet rays, etc. for safety and productivity. In view of the above, it is particularly preferable to use an electron beam or an ultraviolet ray. In the case of curing with heat, in consideration of the heat resistance of the plastic itself, the heating temperature is preferably 140 ° C. or lower, more preferably 100 ° C. or lower.

[Forward scattering layer]
The forward scattering layer is used to improve the viewing angle characteristics (hue and luminance distribution) in the vertical and horizontal directions when the polarizing plate of the present invention is applied to a liquid crystal display device.
In the present invention, a configuration in which fine particles having different refractive indexes are dispersed in a binder is preferable. For example, Japanese Patent Application Laid-Open No. 11-38208 in which the forward scattering coefficient is specified, and Japanese Patent Application Laid-Open No. 2000 in which the relative refractive index between the transparent resin and the fine particles is in a specific range. The construction of JP-A No. 199809, JP-A No. 2002-107512 that defines the haze value as 40% or more can be used.
In addition, in order to control the viewing angle characteristics of haze, the polarizing plate of the present invention is also preferably used in combination with “Lumisty” described in Sumitomo Chemical's technical report “Photofunctional Films” on pages 31-39. be able to.

[Anti-glare layer]
The antiglare (antiglare) layer is used to scatter reflected light and prevent reflection.
The antiglare function is obtained by forming irregularities on the outermost surface (display side) of the liquid crystal display device. The haze of the optical film having an antiglare function is preferably 3 to 30%, more preferably 5 to 20%, and still more preferably 7 to 20%.
The method for forming irregularities on the film surface is, for example, a method of forming irregularities on the film surface by adding fine particles (for example, JP-A No. 2000-271878), relatively large particles (particle size 0.05-2 μm). ) Is added in a small amount (0.1 to 50% by mass) (for example, Japanese Patent Application Laid-Open Nos. 2000-281410, 2000-95893, 2001-100004, and 2001). No. 281407, etc.), a method of physically transferring the uneven shape onto the film surface (for example, as an embossing method, JP-A-63-278839, JP-A-11-183710, JP-A-2000-275401) Etc.) can be preferably used.

  These functional layers are preferably provided on one side or both sides of the polarizer side and the opposite side of the polarizer.

(Liquid crystal display device)
Next, a liquid crystal display device in which the polarizing plate of the present invention is used will be described.
FIG. 2 is an example of a liquid crystal display device in which the polarizing plate of the present invention is used.

As shown in FIG. 2, the liquid crystal display device of the present invention includes a liquid crystal cell (15-19), and an upper polarizing plate 11 and a lower polarizing plate 22 arranged with the liquid crystal cell (15-19) interposed therebetween. Have.
The polarizing plate is sandwiched between a polarizer and a pair of transparent protective films, but is shown as an integrated polarizing plate in FIG.
The liquid crystal cell includes a liquid crystal layer formed of an upper substrate 15 and a lower substrate 18 and liquid crystal molecules 17 sandwiched between them. The liquid crystal cell is different in the alignment state of liquid crystal molecules that perform ON / OFF display. However, the polarizing plate of the present invention can be used in any display mode regardless of the transmissive and reflective types.
An alignment film (not shown) is formed on the surface of the substrates 15 and 18 in contact with the liquid crystal molecules 17 (hereinafter, also referred to as “inner surface”), and by a rubbing process or the like applied on the alignment film, The orientation of the liquid crystal molecules 17 in the state where no electric field is applied or in the state where a low voltage is applied is controlled. Further, on the inner surfaces of the substrates 15 and 18, a transparent electrode (not shown) capable of applying an electric field to the liquid crystal layer made of the liquid crystal molecules 17 is formed.

The rubbing direction of the TN mode is applied in directions perpendicular to each other on the upper and lower substrates, and the magnitude of the tilt angle can be controlled by the strength and the number of rubbing times. The alignment film is formed by applying and baking a polyimide film. The magnitude of the twist angle (twist angle) of the liquid crystal layer is determined by the crossing angle of the upper and lower substrates in the rubbing direction and the chiral agent added to the liquid crystal material. Here, a chiral agent having a pitch of about 60 μm was added so that the twist angle was 90 °.
The twist angle is in the vicinity of 90 ° (85 to 95 °) in the case of a notebook computer, a personal computer monitor, and a liquid crystal display device for a television, and is 0 to 70 ° in the case of use as a reflective display device such as a mobile phone. Set. In the IPS mode and the ECB mode, the twist angle is 0 °. In the IPS mode, electrodes are disposed only on the lower substrate 18 and an electric field parallel to the substrate surface is applied. In the OCB mode, there is no twist angle and the tilt angle is increased, and in the VA mode, the liquid crystal molecules 17 are aligned perpendicular to the upper and lower substrates.

Here, the magnitude of the product Δnd of the thickness d of the liquid crystal layer and the refractive index anisotropy Δn changes the brightness during white display. Therefore, in order to obtain the maximum brightness, the range is set for each display mode.
In general, the crossing angle of the absorption axis 12 of the upper polarizing plate 11 and the absorption axis 23 of the lower polarizing plate 22 is generally perpendicular to obtain a high contrast.
The crossing angle between the absorption axis 12 of the upper polarizing plate 11 of the liquid crystal cell and the rubbing direction of the upper substrate 15 varies depending on the liquid crystal display mode, but is generally set to be parallel or vertical in the TN and IPS modes. In OCB and ECB modes, it is often set to 45 °. However, the optimum value differs in each display mode for adjusting the color tone and viewing angle of the display color, and the present invention is not limited to this range.
The liquid crystal display device in which the polarizing plate is used is not limited to the configuration in FIG. 2 and may include other members. For example, a color filter may be disposed between the liquid crystal cell and the polarizer.
In addition, the above-described viewing angle widening films 13 and 20 may be separately disposed between the liquid crystal cell and the polarizing plate. The polarizing plates 11 and 22 and the viewing angle widening films 13 and 20 may be arranged in a laminated form bonded with an adhesive, or a so-called integrated elliptical polarization using one of the liquid crystal cell side protective films for widening the viewing angle. It may be arranged as a plate.

  When used as a transmission type, a cold cathode or hot cathode fluorescent tube, or a backlight having a light emitting diode, field emission element, or electroluminescent element as a light source can be disposed on the back surface. Further, the liquid crystal display device in which the polarizing plate of the present invention is used may be of a reflective type. In such a case, only one polarizing plate may be disposed on the observation side, and the back of the liquid crystal cell or under the liquid crystal cell. A reflective film is installed on the inner surface of the side substrate. Of course, a front light using the light source may be provided on the liquid crystal cell observation side.

  Hereinafter, the present invention will be described more specifically by way of examples. However, the embodiments of the present invention are not limited to these examples.

<Production of cycloolefin-based resin film A-1>
A pellet of ZEONOR 1420 (hydrogenated ring-opening polymer of norbornenes, manufactured by Nippon Zeon Co., Ltd., Tg 140 ° C.) was used.
The pellet was melt extruded at a barrel temperature of 260 ° C. using a single screw extruder (manufactured by Nippon Steel) with a cylinder inner diameter of 50 mm and a screw L / D of 28, and a width of 650 mm from a coat hanger die with a die temperature of 260 ° C. The molten resin in a sheet form is extruded and brought into intimate contact with the first cooling drum (diameter 200 mm, temperature T1: 135 ° C., peripheral speed R1: 12.50 m / sec), immediately the first cooling drum is then applied by the knife coater, and then the second cooling drum (Diameter 350 mm, temperature T2: 125 ° C., peripheral speed R2: 14.46 m / sec), and then contact with the third cooling drum (diameter 350 mm, temperature T3: 80 ° C., peripheral speed R3: 14.40 m / sec) sequentially. The front and back surfaces are smoothed by sequential cooling and cooling drum surface transfer, and heat transfer is possible with a width of 550 mm (neck-in is 50 mm each on the left and right). Sexual resin film is obtained, after a regulating drum, remove the 30mm from both ends by a cutter as ear, wound into a roll by a winding drum to obtain an optical film of the roll. At this time, the contact time t1 of the sheet-like thermoplastic resin on the first cooling drum is 3.1 (seconds), the resin temperature when leaving the first cooling drum is T1 is 132 (° C.), t1 × (T1-Tg ) Was −12 (unit: second · deg). Thus, a norbornene-based resin film having a thickness of 80 μm was extruded and molded.

(Preparation of polyester resin film A-2)
The polyester chip material was dried to a water content of 50 ppm or less in a Henschel mixer and a paddle dryer dryer, and then melted in an extruder set at a heater temperature of 280 to 300 ° C.
The melted polyester resin was discharged onto a chiller roll electrostatically applied from the die part to obtain an amorphous base.
The amorphous base was stretched in the base flow direction at a stretch ratio of 3.3 times, and then stretched in the base width direction at a stretch ratio of 3.9 times to produce a polyester resin film A-2 having a thickness of 100 μm.

<Preparation of polycarbonate resin film A-3>
Polycarbonate resin (viscosity average molecular weight 40,000, bisphenol A type) 100 parts, 2- (2′hydroxy-3 ′, 5′-di-t-butylphenyl) -benzotriazole 1.0 part, methylene chloride 430 parts, methanol 90 parts were put into an airtight container, kept at 80 ° C. under pressure, and completely dissolved with stirring to obtain a dope composition.
Next, this dope composition A was filtered, cooled and kept at 33 ° C., cast uniformly on a stainless steel band, and dried at 33 ° C. for 5 minutes.
Next, after peeling from the stainless steel band, drying was completed while being conveyed by many rolls to obtain a polycarbonate film having a film thickness of 100 μm.

<Preparation of vinylidene chloride resin film A-4>
<< Preparation of coating solution for coating layer 1 >>
[Composition of coating solution for coating layer 1]
-Chlorine-containing polymer: R204 ... 12g
{"Saran Resin R204" manufactured by Asahi Kasei Life & Living Co., Ltd.}
・ Tetrahydrofuran ... 63g

<< Coating of coating layer 1 >>
Using a coater having a throttle die on an 80 μm thick triacetylcellulose film (TAC-TD80U, manufactured by FUJIFILM Corporation), the coating solution for coating layer 1 is applied to a thickness of 3 μm after drying. did. It apply | coated on conditions with a conveyance speed of 30 m / min, and it dried at 100 degreeC for 5 minute (s) at 60 degreeC, and wound up.

<Preparation of vinyl alcohol-based resin layer coating films A-5 and A-6>
<< Preparation of coating layer 2 made of vinyl alcohol polymer >>

[Preparation of coating solution for coating layer 2]
・ Vinyl alcohol polymer HR-3010 (manufactured by Kuraray Co., Ltd.) ... 5 parts by mass・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 10 parts by mass
・ Water ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 100 parts by mass

  ME-100 was mixed with water so as to have a desired concentration, and then subjected to a high-pressure dispersion treatment at 30 Mpa three times using a high-pressure disperser to be dispersed in water. HR-3010 was dissolved by stirring with 95 ° C. water for 2 hours. Then, both were mixed and the coating liquid of the coating layer 2 was produced.

<< Coating of coating layer 2 >>
The side on which the coating layer of triacetylcellulose (TAC-TD80U, manufactured by FUJIFILM Corporation) was provided was saponified at 50 ° C. with a 1 mol / L alkaline solution.
Thereafter, using a coater having a throttle die on the saponified surface of the triacetylcellulose film, the coating solution for coating layer 2 was applied so that the film thickness after drying was 5 μm. Then, it apply | coated on conditions with a conveyance speed of 30 m / min, dried at 130 degreeC for 5 minute (s), and wound up.

<Production of first protective film>
<< Production of First Protective Film B-1 >>
−Pretreatment−
On both sides of the cycloolefin-based resin film A-1, a high-frequency transmitter (Corona Generator HV05-2, manufactured by Tamtec) is used. Corona discharge treatment was performed for 3 seconds under conditions of a length of 240 mm and a distance between work electrodes of 1.5 mm, and the surface was modified so that the surface tension was 0.072 N / m.

<Coating the undercoat layer>
The undercoat coating solution shown below was applied to both surfaces of the pretreated cycloolefin resin film A-1 so that the dry film thickness was 90 nm.

[Composition of coating solution for undercoat layer]
・ Styrene butadiene latex (solid content: 43%) ... 300g
・ 2,4-Dichloro-6hydroxy-s-triazine sodium salt (8%) ... 49 g
・ Distilled water ... 1,600g

<Coating of hard coat layer>
<< Preparation of Sol Solution 1 >>
In a 1,000 mL reaction vessel equipped with a thermometer, a nitrogen inlet tube, and a dropping funnel, 187 g (0.80 mol) of acryloxyoxypropyltrimethoxysilane, 27.2 g (0.20 mol) of methyltrimethoxysilane, 320 g of methanol ( 10 mol) and 0.06 g (0.001 mol) of KF were charged, and 15.1 g (0.86 mol) of water was slowly added dropwise at room temperature with stirring. After completion of the dropwise addition, the mixture was stirred at room temperature for 3 hours, and then heated and stirred for 2 hours under methanol reflux.
Thereafter, low-boiling components were distilled off under reduced pressure, and further filtered to obtain 120 g of sol solution 1. As a result of GPC measurement of the substance thus obtained, the mass average molecular weight was 1,500, and among the components higher than the oligomer component, the component having a molecular weight of 1,000 to 20,000 was 30%. Moreover, from the measurement result of ¹ H-NMR, the structure of the obtained substance was a structure represented by the following general formula (1).

Furthermore, the condensation rate α as determined by ²⁹ Si-NMR was 0.56. From this analysis result, it was found that most of the silane coupling agent sol was a linear structure portion.
From the gas chromatography analysis, the raw material acryloxypropyltrimethoxysilane had a residual rate of 5% or less.

<< Preparation of coating solution for hard coat layer >>
[Composition of coating liquid for hard coat layer]
・ PET-30 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 40.0g
・ DPHA ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 10.0g
・ Irgacure 184 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 2.0g
-SX-350 (30%) ... 2.0g
・ Cross-linked acrylic-styrene particles (30%) ... 13.0g
・ FP-13 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 0.06g
・ Sol solution 1 ... 11.0g
・ Toluene ... 38.5g

  The coating solution was filtered through a polypropylene filter having a pore size of 30 μm to prepare a coating solution for a hard coat layer.

The compounds used are shown below.
PET-30: A mixture of pentaerythritol triacrylate and pentaerythritol tetraacrylate (manufactured by Nippon Kayaku Co., Ltd.)
・ Irgacure 184: Polymerization initiator (Ciba Specialty Chemicals Co., Ltd.)
SX-350: average particle size 3.5 μm cross-linked polystyrene particles (refractive index 1.60, manufactured by Soken Chemical Co., Ltd., 30% toluene dispersion, used after dispersion for 20 minutes at 10,000 rpm with a Polytron disperser)
Crosslinked acrylic-styrene particles: average particle size 3.5 μm (refractive index 1.55, manufactured by Soken Chemical Co., Ltd., 30% toluene dispersion, used after dispersion for 20 minutes at 10,000 rpm with a Polytron disperser)

The prepared cycloolefin-based resin film A-1 is unwound in a roll form, and a coating liquid for hard coat layer is not provided with a coating layer for a polarizing plate protective film on a backup roll using a coater having a throttle die. It was extruded and applied directly onto the surface. After coating at a transfer speed of 30 m / min, drying at 30 ° C. for 15 seconds and 90 ° C. for 20 seconds, and further using a 160 W / cm air-cooled metal halide lamp (made by Eye Graphics Co., Ltd.) under a nitrogen purge. The coating layer is cured by irradiating ultraviolet rays with an irradiation amount of 90 mJ / cm ² to form an anti-glare layer having an anti-glare property with a thickness of 6 μm, wound up, and hard coated on the cycloolefin resin film A-1. A layer was provided.

<Coating of low refractive index layer>
<< Synthesis of Perfluoroolefin Copolymer (1) >>
A 100 mL stainless steel autoclave with a stirrer was charged with 40 mL of ethyl acetate, 14.7 g of hydroxyethyl vinyl ether, and 0.55 g of dilauroyl peroxide, and the system was degassed and replaced with nitrogen gas.
Furthermore, 25 g of hexafluoropropylene (HFP) was introduced into the autoclave and the temperature was raised to 65 ° C. The pressure when the temperature in the autoclave reached 65 ° C. was 0.53 Mpa (5.4 kg / cm ² ).
The reaction was continued for 8 hours while maintaining the temperature, and when the pressure reached 0.31 MPa (3.2 kg / cm ² ), the heating was stopped and the mixture was allowed to cool.
When the internal temperature decreased to room temperature, unreacted monomers were driven out, the autoclave was opened, and the reaction solution was taken out. The obtained reaction solution was poured into a large excess of hexane, and the polymer was precipitated by removing the solvent by decantation.
Further, this polymer was dissolved in a small amount of ethyl acetate and reprecipitated twice from hexane to completely remove the residual monomer. After drying, 28 g of polymer was obtained.
Next, 20 g of the polymer was dissolved in 100 mL of N, N-dimethylacetamide, and 11.4 g of acrylic acid chloride was added dropwise under ice cooling, followed by stirring at room temperature for 10 hours. Ethyl acetate was added to the reaction solution, washed with water, the organic layer was extracted and concentrated, and the resulting polymer was reprecipitated with hexane to obtain 19 g of a perfluoroolefin copolymer (1) represented by the following general formula (2). It was. The resulting polymer had a refractive index of 1.421.

<< Preparation of Sol Solution 2 >>
A stirrer, a reactor equipped with a reflux condenser, 120 parts of methyl ethyl ketone, 100 parts of acryloyloxypropyltrimethoxysilane (KBM-5103, manufactured by Shin-Etsu Chemical Co., Ltd.), 3 parts of diisopropoxyaluminum ethyl acetoacetate were added and mixed. Thereafter, 30 parts of ion-exchanged water was added and reacted at 60 ° C. for 4 hours, and then cooled to room temperature to obtain a sol solution 2.
The mass average molecular weight was 1,600, and among the components higher than the oligomer component, the component having a molecular weight of 1,000 to 20,000 was 100%. Further, from the gas chromatography analysis, the raw material acryloyloxypropyltrimethoxysilane did not remain at all.

<< Preparation of coating solution for low refractive index layer >>
Thermally crosslinkable fluorine-containing polymer having a refractive index of 1.44 containing polysiloxane and hydroxyl group (JTA113, solid content concentration 6%, manufactured by JSR Corporation) 13 g, colloidal silica dispersion MEK-ST-L (trade name, average) Particle size 45 nm, solid content concentration 30%, manufactured by Nissan Chemical Co., Ltd.) 1.3 g, the sol solution 2 0.65 g, methyl ethyl ketone 4.4 g, cyclohexanone 1.2 g were added, and after stirring, the pore size was 1 μm. It filtered with the filter made from a polypropylene, and the low refractive index layer coating liquid 1 was prepared. The refractive index of the layer formed with this coating solution was 1.45.

The cycloolefin resin film A-1 on which the hard coat layer is formed is unwound in a roll form, and the coating liquid for the low refractive index layer is applied to the polarizing plate protective film on the backup roll using a coater having a throttle die. The hard coat layer was applied directly onto the surface on which the hard coat layer was applied.
After drying at 120 ° C. for 150 seconds and further drying at 140 ° C. for 8 minutes, an air-cooled metal halide lamp (manufactured by Eye Graphics Co., Ltd.) with 240 W / cm in an atmosphere with an oxygen concentration of 0.1% by nitrogen purge is used. Then, an ultraviolet ray having an irradiation amount of 300 mJ / cm ² is irradiated, a low refractive index layer having a thickness of 100 nm is formed, wound, and the cycloolefin resin film A-1 having a hard coat layer formed thereon has a lower refractive index. The 1st protective film B-1 in which the layer was formed was produced.

[Measurement of moisture permeability]
As described above, the moisture permeability was calculated according to JIS Z-0208 except that the humidity control condition was changed to 60 ° C. and 95% RH. At this time, the operation of taking out and weighing the cup placed in the thermo-hygrostat at an appropriate time interval is repeated, and the increase in mass per unit time is obtained with two successive weighings, and it becomes constant within 5%. The evaluation continued until.
Moreover, in order to exclude the influence by the moisture absorption etc. of a sample, the blank cup which does not put a hygroscopic agent was measured, and the value of moisture permeability was correct | amended.
The moisture permeability of the first protective film B-1 thus obtained was 5 g / m ² · day.

<< Production of First Protective Films B-2 to B-13 >>
In the same manner as the first protective film B-1, first protective films B-2 to B-13 were prepared based on Table 1 below. In addition, Table 1 also shows the water vapor transmission rate (g / m ² · day) in each of the first protective films B-2 to B-13.
In the measurement of moisture permeability, when measuring the moisture permeability of a polarizing plate protective film having a resin layer containing a vinyl alcohol polymer, the resin layer provided on the transparent substrate film is in contact with the measuring cup. Samples were set in various directions, and the moisture permeability from the transparent substrate film side was measured by the same method as described above.

<Production of second protective film>
<< Preparation of Optical Compensation Film CF-1 >>
The composition shown in the following Table 2 was put into a mixing tank and stirred while heating to 30 ° C. to dissolve each component to prepare a cellulose acylate solution.
A cellulose acylate having a total acyl substitution degree of 2.83, a total acetyl substitution degree of 2.83, and a 6-position substitution degree of 0.90 was used.

The obtained inner layer dope and outer layer dope were cast on a drum cooled to 0 ° C. using a three-layer co-casting die.
The film having a residual solvent amount of 70% by mass was peeled off from the drum, both ends were fixed with a pin tenter, and the film was dried at 80 ° C. while being transported at a draw ratio of 115% in the transport direction, resulting in a residual solvent amount of 10%. By the way, it was dried at 110 ° C.
Thereafter, it was dried at a temperature of 155 ° C. for 20 minutes to produce a cellulose acetate film (outer layer: 3 μm, inner layer: 74 μm, outer layer: 3 μm) having a residual solvent of 0.3% by mass.
The produced cellulose acetate film was used as a polymer substrate C-1, and the optical properties were measured.
The width of the polymer substrate C-1 was 1,340 mm, and the thickness was 75 μm. When the retardation value (Re) at a wavelength of 630 nm was measured using an ellipsometer (M-150, manufactured by JASCO Corporation), the slow axis was 8 nm, which was in a direction perpendicular to the transport direction. Further, the retardation value (Rth) in the thickness direction at a wavelength of 630 nm was measured and found to be 90 nm.
Moreover, it was 90 nm when the retardation value (Rth) in wavelength 630nm was measured. The polymer substrate C-1 was immersed in a 2.0N potassium hydroxide solution (25 ° C.) for 2 minutes, neutralized with sulfuric acid, washed with pure water and dried.
The surface energy of this polymer substrate C-1 was determined by a contact angle method and found to be 63 mN / m.

<Formation of optically anisotropic layer>
On the polymer substrate C-1 produced above, an alignment film coating solution having the following composition was applied at a coating amount of 28 mL / m ² with a # 16 wire bar coater. Drying was performed with warm air of 60 ° C. for 60 seconds, and further with warm air of 90 ° C. for 150 seconds.

[Alignment film coating solution composition]
・ Modified polyvinyl alcohol represented by the following general formula (4): 10 parts by mass, water: 371 parts by mass, methanol ... 119 parts by mass
・ Glutaraldehyde (crosslinking agent) ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 0.5 parts by mass

  Thereafter, the alignment film was rubbed. The rubbing direction was 45 ° with the slow axis (measured at a wavelength of 632.8 nm) of the polymer substrate C-1.

[Formation of liquid crystal layer]
41.01 parts by mass of a discotic liquid crystalline compound represented by the following general formula (5), 4.06 parts by mass of ethylene oxide-modified trimethylolpropane triacrylate (V # 360, manufactured by Osaka Organic Chemical Co., Ltd.), cellulose acetate butyrate (CAB531-1, manufactured by Eastman Chemical Co., Ltd.) 0.35 parts by mass, photopolymerization initiator (Irgacure 907, manufactured by Ciba Geigy) 1.35 parts by mass, sensitizer (Kayacure DETX, manufactured by Nippon Kayaku Co., Ltd.) ) 0.45 parts by mass, and 0.1 parts by mass of the following fluorine-containing surfactant were dissolved in 102 parts by mass of methyl ethyl ketone to form a coating solution. It apply | coated with the wire bar and heated for 2 minutes in the state of 130 degreeC, and the discotic liquid crystalline compound was orientated.
Next, UV irradiation was performed for 1 minute using a 120 W / cm high-pressure mercury lamp at 100 ° C. to polymerize the discotic liquid crystalline compound. Then, it stood to cool to room temperature.
Thus, the 2nd protective film CF-1 was produced as an optical compensation film in which the optically anisotropic layer was formed. The in-plane retardation value Re of the optically anisotropic layer measured at a wavelength of 546 nm was 38 nm.
Further, the difference between the in-plane retardation (Re10) at 25 ° C. relative humidity of 10% and the in-plane retardation (Re80) at 25 ° C. relative humidity of 80% is 12.1 nm, which is 25 ° C. relative humidity at 60%. The value Gr divided by the in-plane retardation (Re60) was 0.40.

<< Production of Cellulose Acylate Films C-2 to C-10 >>
In the production of the second protective film CF-1, cellulose acylate films C-2 to C-10 are produced in the same manner as the second protective film CF-1, except that an optically anisotropic layer is formed. did.
In producing the cellulose acylate films C-2 to C-10, cellulose acylates CTA-1 to CTA-10 having the characteristics shown in Table 3 and solvents S-1 to S-3 shown in Table 4 were used. Then, as shown in Table 5, dopes D-1 to D-10 were prepared. Each dope was prepared in the following manner for each of the solvent S-1, the solvent S-2, and the solvent S-3.

[In the case of solvent S-1]
The solvent of solution composition 1 is mixed in a 400 L stainless steel dissolution tank having a stirring blade and circulating cooling water around the outer periphery, and then additives other than cellulose acylate are dissolved. Next, the cellulose acylate powder was gradually added while stirring to prepare a total of 300 kg. The solvents dichloromethane, butanol, and methanol were all those having a water content of 0.2% by mass or less.
The tank was sealed, the cooling water around the tank was changed to 60 ° C. and dissolved for 2 hours with stirring to prepare a cellulose acylate solution. Next, the solution was filtered with a filter paper having an absolute filtration accuracy of 0.01 mm (manufactured by Toyo Filter Paper Co., Ltd., # 63), and further filtered with a filter paper having an absolute filtration accuracy of 2.5 μm (manufactured by Pall, FH025).
A liquid having the following second solution composition is prepared in another mixing tank, and 474 parts by mass of the first solution and 25 parts by mass of the second solution are mixed.

[Second solution composition]
・ Fine particles (Silicon dioxide (particle size 20 nm), Mohs hardness approx. 7) 0.5 parts by mass ・ Methylene chloride ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・.... 87 parts by mass
・ Methanol ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 13 parts by mass

[In the case of solvents S-2 and S-3]
A 400L stainless steel dissolution tank having stirring blades and circulating cooling water around its periphery is charged with a solvent so as to have the composition shown in Table 2. Further, the plasticizer / release agent and additives shown in Table 3 are added. In addition, it was dissolved. While stirring, the cellulose acylate powder was gradually added to prepare a total of 200 kg.
The solvents methyl acetate, 1-butanol, acetone, ethanol, and methanol were all those having a water content of 0.2% by mass or less.
First, the powder of cellulose triacylate is charged into a dispersion tank, and the inside of the tank is depressurized to 1,300 Pa. The stirring shear rate is initially 15 m / sec (shear stress 5 × 10 ⁴ kgf / m / sec ² ). Of a dissolver type eccentric stirring shaft that stirs at a peripheral speed of 50 mm, and an anchor blade on the central axis and a stirring speed of 1 m / sec (shear stress 1 × 10 ⁴ kgf / m / sec ² ). Dispersed for minutes. The starting temperature of the dispersion was 25 ° C., and the final temperature reached 35 ° C. by flowing cooling water.
After completion of the dispersion, high-speed stirring was stopped, and the peripheral speed of the anchor blade was set to 0.5 m / sec, and further stirred for 100 minutes to swell the cellulose triacylate flakes. Until the end of swelling, the inside of the tank was pressurized to 0.12 MPa with nitrogen gas. At this time, the oxygen concentration in the tank was less than 2 vol%, so that no problem was found in terms of explosion protection.
Moreover, it confirmed that the moisture content in dope was 0.2 mass% or less. 470 parts by mass of this liquid and 25 parts by mass of the following second solution composition prepared separately were mixed.

[Second solution composition]
・ Fine particles (silicon dioxide (particle size 20 nm), Mohs hardness approx. 7) 0.5 parts by mass ・ Methyl acetate ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・... 85 parts by mass Acetone ... 7 parts by mass
・ Ethanol ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 8 parts by mass

The obtained non-uniform gel solution is fed with a screw pump whose center is heated to 30 ° C., cooled from the outer periphery of the screw, and the cooling portion is set at −75 ° C. for 3 minutes. I let it pass.
Cooling was performed using a -80 ° C refrigerant cooled by a refrigerator.
And the solution obtained by cooling was heated at 35 degreeC during liquid feeding with the screw pump, and was transferred to the stainless steel container.
After stirring at 50 ° C. for 2 hours to obtain a uniform solution, the solution is filtered with a filter paper with absolute filtration accuracy of 0.01 mm (manufactured by Toyo Filter Paper Co., Ltd., # 63), and further with filter paper with absolute filtration accuracy of 2.5 μm (manufactured by Pole, FH025).
The obtained cellulose derivative solution is heated to 110 ° C. and 1 MPa at the heating part pressure part of the liquid feeding pipe, and is released to normal pressure (about 0.1 Mpa) to volatilize the organic solvent and cool. A solution having a solid concentration of about 24% at a temperature of 40 ° C. was obtained.

  In addition, all the plasticizers shown in Table 5 were used by mixing 2 parts by mass of triphenyl phosphate and 1 part by mass of biphenyl diphenyl phosphate. As the release agent, citric acid ethyl ester (a mixture having an ethyl group substitution degree of 0 to 3) was used. Furthermore, dope additives M1 to M4 shown in Table 5 are shown below.

The dopes D-1 to D-10 thus prepared were cast on a mirror surface stainless steel drum support. After peeling the film from the drum while stretching about 5% in the length direction, the film was dried while being stretched in the width direction at the tenter part, and further dried while being conveyed between a large number of rolls and then wound.
The thickness, thickness direction retardation (Rth), and in-plane retardation (Re) of the cellulose acylate films C-1 to C-10 thus obtained were measured. The results and the stretching ratio in the width direction are shown in Table 6. In addition, the width direction extending | stretching rate shown in Table 6 shows the dimension increased by extending | stretching from the width dimension of the film before extending | stretching with the percentage with respect to the width dimension of the film before extending | stretching.

<< Production of Cellulose Acylate Films C11 to C12 >>
[Production of Cellulose Acylate CTA-11]
A 1 L three-necked flask equipped with a mechanical stirrer, thermometer, condenser, and dropping funnel was weighed with 40 g of cellulose acetate (acetyl substitution degree 2.41), 46.0 mL of pyridine, and 300 mL of methylene chloride, and stirred at room temperature. .
To this, 62.4 mL of benzoyl chloride was slowly added dropwise, and after addition, the mixture was further stirred at room temperature.
After the reaction, when the reaction solution was added to 4 L of methanol with vigorous stirring, a white solid was precipitated.
The white solid was separated by suction filtration and washed with a large amount of methanol three times.
The obtained white solid was dried at 60 ° C. overnight and then vacuum dried at 90 ° C. to obtain the target compound (cellulose acylate) CTA-11 as a white powder. The total substitution degree of the acyl group of the compound CTA-11 was 3.0, and the substitution degree of the aromatic acyl group was 0.58.

[Preparation of Cellulose Acylate Film C11]
After the cellulose acylate CTA-11 was dried at 120 ° C. for 2 hours, the composition described below was put into a mixing tank and dissolved by stirring to prepare a cellulose acylate solution.

[Composition of cellulose acylate solution]
-Methylene chloride 291 parts by mass-Methanol 44 parts by mass-Cellulose acylate (CTA-11) 100 parts by mass
・ 0.25 parts by mass of silicon dioxide fine particles

The cellulose acylate solution was heated to 30 ° C., and was cast on a mirror surface stainless steel support through a cast Giuser having a width of 800 mm. The casting point was set on a roll set at 22 ° C., and the temperature of the other roll supporting the band was 30 ° C.
Moreover, the space temperature of the whole casting part was set to 70 degreeC. The casting speed was 3 m / min and the coating width was 80 cm.
The cellulose acylate film which had been cast and rotated 50 cm before the cast part was peeled off from the band, and both ends of the film were gripped with a tenter. The tenter part at 110 ° C. was conveyed while keeping the film width constant.
Thereafter, the film was removed from the tenter, the clip traces at both ends of the film were cut off, and the film was dried at 135 ° C. to 145 ° C. consisting of a plurality of pass rolls so that the residual solvent amount was 0.1% or less. .
After drying, it was wound around a winding core to obtain a long cellulose acylate film C11 having a thickness of 80 μm.
Using the automatic birefringence meter (KOBRA-21ADH, manufactured by Oji Scientific Instruments Co., Ltd.) for the obtained cellulose acylate film C11, the dependency of retardation on the light incident angle is measured, and the optical characteristics are measured. As a result of calculation, Re = 4.5 nm and Rth = -141 nm.
Further, the absolute value of the difference between the in-plane retardation (Re10) at 25 ° C. relative humidity of 10% and the in-plane retardation (Re80) at 25 ° C. relative humidity of 80% of the cellulose acylate film C11 is 25 ° C. relative humidity of 60%. The value Gr divided by the in-plane retardation (Re60) in% was 0.16.
Table 6 shows the width direction stretching ratio, thickness, in-plane retardation (Re), thickness direction retardation (Rth), and Gr value of the cellulose acylate film C-11.

[Production of Cellulose Acylate Film C12]
A long cellulose acylate film C12 was obtained in the same manner as the production method of the cellulose acylate film C11 except that the completed thickness was 50 μm.
Using the automatic birefringence meter (KOBRA-21ADH, manufactured by Oji Scientific Instruments Co., Ltd.) for the obtained cellulose acylate film C12, the dependency of retardation on the light incident angle is measured, and the optical characteristics are measured. As a result of calculation, Re = 2 nm and Rth = −90 nm.
The absolute value of the difference between the in-plane retardation (Re10) at 25 ° C. relative humidity of 10% and the in-plane retardation (Re80) at 25 ° C. relative humidity of 80% of the cellulose acylate film C12 is 25 ° C. relative humidity 60 The value Gr divided by the in-plane retardation (Re60) in% was 0.2.
Table 6 shows the width direction stretching ratio, thickness, in-plane retardation (Re), thickness direction retardation (Rth), and Gr value of the cellulose acylate film C-12.

  Thereafter, the produced cellulose acylate films C-1 to C-12 were immersed in a 6% aqueous sodium hydroxide solution at 50 ° C. for 2 minutes, washed with water and dried.

<< Preparation of Optical Compensation Film CF-2 >>
[Coating of optically anisotropic layer]
On the cellulose acylate film C-2 produced above, an optical anisotropic layer was provided in the same manner as the optical compensation film CF-1 to produce an optical compensation film CF-2. The optical compensation film CF-2 thus produced had Re of 28 nm and Rth of 170 nm. The in-plane retardation at 25 ° C. relative humidity of 10% (Re10) and the in-plane retardation at 25 ° C. relative humidity of 80% (Re80). The value Gr obtained by dividing the absolute value of the difference by the in-plane retardation (Re60) at 25 ° C. and a relative humidity of 60% was 0.70.

<< Preparation of Optical Compensation Film CF-3 >>
[Coating of optically anisotropic layer]
On the cellulose acylate film C-3 produced above, an alignment film is applied in the same manner as the optical compensation film CF-1, the film is conveyed at a speed of 20 m / min, and is rubbed at 45 ° with respect to the longitudinal direction. A rubbing roll (300 mm diameter) was set as described above, and the rubbing treatment was performed on the alignment film installation surface by rotating at 650 rpm.
Thereafter, on the alignment film subjected to the rubbing treatment, 41.01 kg of a discotic liquid crystal compound, 4.06 kg of ethylene oxide-modified trimethylolpropane triacrylate (V # 360, manufactured by Osaka Organic Chemical Co., Ltd.), cellulose acetate butyrate ( CAB531-1, manufactured by Eastman Chemical Co., Ltd.) 0.35 Kg, photopolymerization initiator (Irgacure 907, manufactured by Ciba Geigy Co.) 1.35 Kg, sensitizer (Kayacure DETX, manufactured by Nippon Kayaku Co., Ltd.) 0.45 Kg, 0.1 kg of fluoroaliphatic group-containing copolymer (Megafac F780 manufactured by Dainippon Ink, Inc.) was added to a coating solution in which 0.45 kg of citrate ester (AS3 manufactured by Sankyo Chemical Co., Ltd.) was dissolved in 102 kg of methyl ethyl ketone. , # 3.2 wire bar at 391 revolutions, same as film transport direction Rotate the direction was continuously coated on the orientation film surface of the C-3 that is conveyed at 20 m / min.
In the process of continuously heating from room temperature to 100 ° C., the solvent is dried, and then the film surface wind speed of the discotic liquid crystal compound layer is 2.5 m / sec parallel to the film transport direction in the 130 ° C. drying zone. And heated for about 90 seconds to align the discotic liquid crystal compound.
Next, the film is transported to a drying zone at 80 ° C., and an ultraviolet ray with an illuminance of 600 mW is applied by an ultraviolet irradiation device (ultraviolet lamp: output 160 W / cm, emission length 1.6 m) with the surface temperature of the film being about 100 ° C. Irradiation was carried out for 4 seconds to advance the crosslinking reaction, and the discotic liquid crystal compound was fixed to the orientation.
Then, it was allowed to cool to room temperature and wound into a cylindrical shape to form a roll.
In this way, a roll-shaped optical compensation film (CF-3) was produced. The optically anisotropic layer thus prepared had Re of 30 nm and Rth of 90 nm, and the difference between the in-plane retardation (Re10) at 25 ° C. and 10% relative humidity and the in-plane retardation (Re80) at 25 ° C. and 80% relative humidity. The value Gr obtained by dividing the absolute value of n by the in-plane retardation (Re60) at 25 ° C. and a relative humidity of 60% was 0.80.

<< Preparation of Optical Compensation Film CF-4 >>
[Coating of optically anisotropic layer]
On the cellulose acylate film C-4 produced above, an alignment film was applied in the same manner as the optical compensation film CF-1, and an optically anisotropic layer was provided so that Re was 30 nm and Rth was 80 nm. Thus, an optical compensation film (CF-4) was produced. The optical compensation film CF-4 thus produced had Re of 28 nm and Rth of 130 nm. The in-plane retardation (Re10) at 25 ° C. and 10% relative humidity and the in-plane retardation (Re80) at 25 ° C. and 80% relative humidity. A value Gr obtained by dividing the absolute value of the difference by the in-plane retardation (Re60) at 25 ° C. and 60% relative humidity was 0.6.

(Example 1)
(Preparation of polarizing plate)
<Production of polarizer>
A 120 μm-thick polyvinyl alcohol film was immersed in an aqueous solution containing 1 part by mass of iodine, 2 parts by mass of potassium iodide, and 4 parts by mass of boric acid, and stretched 4 times at 50 ° C. to produce a polarizer.

Hydrogenated product of maleic anhydride-modified styrene / butadiene / styrene block copolymer (melt index value is 200 g, 1.0 g / 10 min at 5 kg load, styrene block content is 30% by mass, hydrogenation rate is 80% or more, anhydrous 2 parts by weight of maleic acid added 2%) was dissolved in a mixed solvent of 8 parts by weight of xylene and 40 parts by weight of methyl isobutyl ketone and filtered through a polytetrafluoroethylene filter having a pore size of 1 μm to obtain a primer solution. .
Then, without providing the hard coat layer of the first protective film B-1, the polarizer is applied to the surface subjected to the corona treatment and the surface where the optically anisotropic layer of the saponified WV film is not applied. By bonding the first polarizing plate to the polarizer using the prepared primer solution as an adhesive, and bonding the second protective film CF-1 to the polarizer using a 5% aqueous solution of fully saponified polyvinyl alcohol as an adhesive. A polarizing plate was produced. Similarly, the 1st protective film B-7, the polarizer, and the 2nd protective film CF-1 were bonded together in this order, and the lower side polarizing plate was produced.

<Durability evaluation of polarizing plate>
The degree of polarization after the polarizing plate obtained as described above was allowed to stand for 1,000 hours in an environment of 60 ° C. and 95% RH was measured and evaluated based on the following evaluation criteria. The results are shown in Table 6. In addition, as above-mentioned, the polarization degree was calculated | required from the said Numerical formula (1) in wavelength 550nm.
Thus, as a result of evaluating the durability of the polarizing plate of Example 1, the degree of polarization was 99.5%, which was a satisfactory level.

[Evaluation criteria]
○: No problem in practical use with a polarization degree of 99% or more.
Δ: The degree of polarization is 98% or more and less than 99%, and there is no practical problem.
X: The degree of polarization is less than 98%, which is a practical problem.

(Production of liquid crystal display device)
A pair of polarizing plates (upper polarizing plate and lower polarizing plate) provided in a 20-inch liquid crystal display device (LC-20V1, manufactured by Sharp Corporation) using a TN type liquid crystal cell is peeled off, and this is used instead. The polarizing plates produced in Example 1 were attached to the observer side and the backlight side one by one through an adhesive so that the second protective film was on the liquid crystal cell side. At this time, each polarizing plate was arranged so that the transmission axis of the polarizing plate on the observer side (upper polarizing plate) and the transmission axis of the polarizing plate on the backlight side (lower polarizing plate) were orthogonal to each other. At this time, a polarizing plate using a first protective film having a hard coat layer is disposed on the observer-side polarizing plate (upper polarizing plate), and the backlight-side polarizing plate (lower polarizing plate) is provided. A polarizing plate having no hard coat layer was disposed.

<Evaluation of liquid crystal display device>
Next, a measuring instrument (EZ-Contrast 160D, manufactured by ELDIM) is used to measure the hue when displaying black with an azimuth angle of 45 ° with respect to the horizontal direction of the liquid crystal display screen and a polar angle of 60 ° with respect to the normal direction of the screen surface. ) Was used as an initial value.
Next, this liquid crystal display device was left in a room at normal temperature and normal humidity (no humidity control at about 25 ° C. and 60% RH) for one week, and the color during black display was measured again.
Further, this liquid crystal display device was left at 25 ° C. and 10% RH for 1 day, and the color was measured during black display. Further, the same liquid crystal display device was left at 25 ° C. and 80% RH for 1 day, and the color was measured when displaying black.

  About the obtained color measurement, the color change was evaluated based on the following evaluation criteria.

[Evaluation criteria]
◎: Black color change (ΔE ^* ) is less than 0.1 and practically no problem ○: Black color change (ΔE ^* ) is 0.1 or more and less than 0.3, practically no problem △ : Black color change (ΔE ^* ) is 0.3 or more and less than 0.5, there is a practical problem ×: Black color change (ΔE ^* ) is 0.5 or more, there is a practical problem

  Further, as a result of observing the manufactured liquid crystal display device, neutral black display was realized in the front direction and the viewing angle direction.

(Preparation of polarizing plates in Examples 2 to 15 and Comparative Examples 1 to 13)
In the same manner as in Example 1, using the first protective films B-2 to B-13 produced above and the second protective films CF-1 to CF-4, C-5 to C-10, Polarizing plates were produced with the combinations shown in Table 7. At this time, B4 to B6, B10 to B13, and the second protective film were immersed in a 1.5 mol / L, 55 ° C. NaOH aqueous solution for 2 minutes, then neutralized, washed with water, saponified, Then, a 5% aqueous solution of completely saponified polyvinyl alcohol was bonded to the polarizer as an adhesive. Moreover, the protective film of B2, B3, and B7-B9 was bonded together with the polarizer like Example 1 after the corona treatment.

<Evaluation of polarizing plates of Examples 2 to 5, Comparative Examples 1 to 3, and Comparative Example 12>
<< Evaluation with TN mode liquid crystal cell >>
Except that the polarizing plate to be used was changed as shown in Table 7, the polarizing plates of Examples 2 to 5, Comparative Examples 1 to 3, and Comparative Example 12 were mounted on a liquid crystal display device in the same manner as in Example 1. The color change was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 7.

<Evaluation of Polarizing Plate of Example 6 and Comparative Example 4>
<< Production of OCB Mode Liquid Crystal Cell >>
A polyimide film was provided as an alignment film on a glass substrate with an ITO electrode, and a rubbing treatment was performed.
The rubbing treatment was performed so that the two glass substrates were in opposite directions. Two glass substrates were opposed to each other so that the cell gap (d) was 8 μm. A liquid crystal compound having a Δn of 0.1396 (ZLI1132, manufactured by Merck & Co., Inc.) was injected into the cell gap to produce an OCB mode liquid crystal cell.
In the OCB mode liquid crystal cell, two polarizing plates prepared as described above were arranged so that the liquid crystal cell was sandwiched between the optically anisotropic layer of the optical compensation film and the glass substrate of the liquid crystal cell.
The rubbing direction of the alignment film of the OCB mode liquid crystal cell and the rubbing direction of the alignment film of the optical compensation film were arranged to be antiparallel. Polarizing elements were arranged in crossed Nicols on both sides. At this time, the change in color was evaluated in the same manner as in Example 1 by using the polarizing plates of Example 6 and Comparative Example 4 in the manufactured OCB type liquid crystal display device. The evaluation results are shown in Table 7.

<Evaluation of polarizing plates of Example 7 and Comparative Example 5>
<< Production of ECB Mode Liquid Crystal Cell >>
In the liquid crystal cell, a nematic liquid crystal material having a cell gap of 3.5 μm and a positive dielectric constant anisotropic layer was sealed between the substrates by drop injection, and Δn · d of the liquid crystal layer was 300 nm.
The liquid crystal material has a positive dielectric anisotropy, a refractive index anisotropy, Δn = 0.0854 (589 nm, 20 ° C.), and a nematic liquid crystal of about Δε = + 8.5 (for example, MLC-9100 manufactured by Merck). It was used.
Further, the crossing angle of the alignment axes (rubbing axes) of the upper substrate and the lower substrate is 0 °, and the rubbing direction (alignment control direction) of the upper and lower substrates of the liquid crystal cell is later bonded to the upper and lower polarizing plates. However, it intersects with the slow axis (parallel to the casting direction) of the support of the optically anisotropic layer at 45 °.
The absorption axis of the polarizing film intersected with the alignment direction (rubbing direction) of the liquid crystal cell by approximately 45 °, and the crossing angle of the absorption axes of the upper and lower polarizing films was approximately 90 °.
The color change at the time of using the polarizing plate of Example 7 and Comparative Example 5 was evaluated for the produced ECB type liquid crystal display device. The evaluation results are shown in Table 7.

<Evaluation of polarizing plates of Examples 8 to 9 and Comparative Examples 6 to 7>
The polarizing plate and retardation film provided in the VA liquid crystal display device (LC-26GD3, manufactured by Sharp Corporation) are peeled off, and the polarizing plates of Examples 8 to 9 and Comparative Examples 6 to 7 are used instead of the transmission axes. Was attached to match the polarizing plate attached to the product. Thereafter, the color change was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 7.

<Evaluation of polarizing plates of Examples 10 and 15 and Comparative Example 8>
<< Preparation of first retardation film >>
Polyimide synthesized from 2,2′-bis (3,4-dicarboxyphenyl) hexafluoropropane and 2,2′-bis (trifluoromethyl) -4,4′-diaminobiphenyl was used, and cyclohexanone was used as a solvent. The solution prepared at 15% by mass was applied onto a 50 μm thick triacetylcellulose film.
Thereafter, the film was dried at 100 ° C. for 10 minutes to obtain a thin film having a residual solvent amount of 7% and a thickness of 6 μm.
Thereafter, the thin film formed on the triacetyl cellulose film is stretched uniaxially by 5% at a temperature of 160 ° C. together with the base material (triacetyl cellulose film), peeled off from the triacetyl cellulose film, and the first retardation film is removed. Obtained.
The characteristics of the first retardation film were Δnd = 60 nm, Rth = 250 nm, d = 5.5 μm, Δn = (nx−nz) = 0.045, and nx>ny> nz. .

The polarizing plate and retardation film provided in the VA liquid crystal display device (LC-26GD3, manufactured by Sharp Corporation) are peeled off, and the polarizing axes of Examples 10 and 15 and Comparative Example 8 are used instead. A liquid crystal display device was manufactured by pasting the film so as to coincide with the polarizing plate attached to the film.
It should be noted that the liquid crystal cell side (second protective film side) of the polarizing plate on the backlight side (lower polarizing plate) has the first through a pressure-sensitive adhesive so that the nx direction and the polarizing plate absorption axis are orthogonal to each other. The retardation film of was stuck together. Further, the polarizing plate on the observer side (upper polarizing plate) was bonded to the liquid crystal cell via an adhesive so that the absorption axes of the polarizing plates were orthogonal to each other without using the first retardation film. .
Thereafter, the color change was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 7.

<Evaluation of Polarizing Plate of Example 11 and Comparative Example 9>
<< Production of Second Retardation Film >>
A 135 μm-thick norbornene resin film (manufactured by JSR, Arton) was stretched at 175 ° C. with a tenter stretching machine to have a refractive index characteristic of nx>ny> nz, Re 40 nm, and Rth 200 nm. A second retardation film was produced.
After that, the polarizing plate and retardation film provided in the IPS liquid crystal display device (Th-26LX300, manufactured by Matsushita Electric Industrial Co., Ltd.) are peeled off. Instead, the polarizing plate of the present invention is used as the transmission axis of the polarizing plate. It stuck so that it might correspond with the polarizing plate stuck.
The second retardation film was bonded to the liquid crystal cell side (second protective film side) of the observer-side polarizing plate (upper polarizing plate) via an adhesive. Moreover, the polarizing plate (lower polarizing plate) on the backlight side was bonded to the liquid crystal cell via an adhesive without using the second retardation film.
Thereafter, the color change was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 7.

<Evaluation of polarizing plates of Example 12 and Comparative Example 10>
<< Production of Third Retardation Film >>
A 17% methylene chloride solution of polycarbonate having a weight average molecular weight of 80,000 was cast on a stainless steel band, and after the residual volatile content became 3%, the film was stretched by 15% in a temperature condition of 158 ° C. By uniaxial stretching, a third retardation plate made of a polycarbonate resin having a retardation value (measured with light of 590 nm) of Re = 15 nm and Rth = 270 nm was obtained.

<< Production of Fourth Retardation Film >>
A norbornene resin (trade name “ZEONOR 1420R”; manufactured by Nippon Zeon Co., Ltd.) is stretched with a tenter stretching machine, has a refractive index characteristic of nx>ny> nz, Re is 213 nm, and Rth is 106 nm. A film was prepared.
Thereafter, the polarizing plate and the retardation film provided in the IPS liquid crystal display device (Th-26LX300, manufactured by Matsushita Electric Industrial Co., Ltd.) are peeled off. Instead, as shown in Table 7, the polarizing plate of the present invention is used. Was attached so that the transmission axis of the polarizing plate coincided with the polarizing plate attached to the product.
The third retardation film was bonded to the liquid crystal cell side (second protective film side) of the observer side polarizing plate (upper polarizing plate) via an adhesive. The fourth retardation film was bonded to the backlight side polarizing plate (lower polarizing plate) via an adhesive.
The polarizing plate produced as described above was evaluated for color change using an IPS liquid crystal display device in the same manner as in Example 11.

<Evaluation of Polarizing Plate of Example 13 and Comparative Example 11>
In Example 11, a liquid crystal display device of Example 13 was produced in the same manner as in Example 11 except that the third retardation film was used instead of the first retardation film. Similarly, the color change was evaluated using an IPS liquid crystal display device. The results are shown in Table 7.

  In Comparative Example 9, a liquid crystal display device of Comparative Example 11 was produced in the same manner as Comparative Example 9 except that the third retardation film was used instead of the first retardation film. Similarly, the color change was evaluated using an IPS liquid crystal display device. The results are shown in Table 7.

<Evaluation of Polarizing Plate of Example 14>
In Example 13, except that the first protective film B-12 was used instead of the first protective film B-7 used for the polarizing plate on the backlight side (lower polarizing plate). The liquid crystal display device of Example 14 was produced in the same manner as in Example 13, and the color change was evaluated using the IPS type liquid crystal display device in the same manner as in Example 13. The results are shown in Table 7.

(Preparation of polarizing plate of Comparative Example 13)
In Example 1, the first protective film and the second protective film of the polarizing plate on the viewer side (upper polarizing plate) and the polarizing plate on the backlight side (lower polarizing plate) are all the first protective film. A liquid crystal display device of Comparative Example 13 was produced in the same manner as in Example 1 except that the protective film B-7 (cycloolefin-based resin film A-1 produced in Example 1) was used. In-plane retardation (Re10) at 25 ° C. relative humidity of 10% and surface at 25 ° C. relative humidity of 80% of the first protective film B-7 (cycloolefin resin film A-1 produced in Example 1) The value Gr obtained by dividing the absolute value of the difference from the inner retardation (Re80) by the in-plane retardation (Re60) at 25 ° C. and 60% relative humidity was 0.04. In Comparative Example 13, productivity was remarkably reduced.

<Polarizing plate evaluation of Examples 16-17>
<< Production of Fifth Retardation Film >>
A cast film is prepared from a dope solution prepared by dissolving a polycarbonate-polystyrene copolymer in methylene chloride, and a retardation film having Re = 140 nm and Rth = 70 nm is obtained by uniaxial stretching at a temperature of 175 ° C. It was.
Thereafter, the polarizing plate and the retardation film provided in the IPS liquid crystal display device (Th-26LX300, manufactured by Matsushita Electric Industrial Co., Ltd.) are peeled off. Instead, as shown in Table 7, the polarizing plate of the present invention is used. Was attached so that the transmission axis of the polarizing plate coincided with the polarizing plate attached to the product.
In addition, on the liquid crystal cell side (second protective film side) of the polarizing plate (upper polarizing plate) on the viewer side, the slow axis of the fifth retardation film is the viewer-side polarizing plate via an adhesive. They were pasted so as to be parallel to the absorption axis.
The polarizing plate produced as described above was evaluated for color change using an IPS liquid crystal display device in the same manner as in Example 11. The results are shown in Table 7.

As shown in Table 7, it was recognized that the polarizing plates of Examples 1 to 17 had higher durability than the polarizing plates of Comparative Examples 1 to 12.
In addition, it was confirmed that the liquid crystal display devices of Examples 1 to 17 were superior in productivity to the liquid crystal display devices of Comparative Examples 1 to 12 and the color stability over time was high. In particular, in Examples 8 to 17 using liquid crystal cells of VA mode and IPS mode, the effect is clear, and among them, the substitution degree of the acyl group of the second protective film is within the range specified in the present invention. The remarkable effect was recognized in Example 8 and Example 12 which are the inside.
Furthermore, since Comparative Example 13 provided with a polarizing plate using a film with low moisture permeability on both sides of the polarizer did not allow water to escape from the polarizer after bonding, the time required for subsequent drying was measured in Examples 1 to 17. And it took several times as compared with Comparative Examples 1-11, and was not suitable for practical use in production, resulting in poor productivity.

The polarizing plate of the present invention is excellent in productivity, has little display unevenness, has a temporal stability of color (high durability), and can be suitably used for a liquid crystal display device.
The liquid crystal display device of the present invention is excellent in productivity, has little display unevenness, and has a color stability over time, and should be suitably used for mobile phones, monitors for personal computers, televisions, liquid crystal projectors, and the like. Can do.

FIG. 1A is a cross-sectional view showing the configuration of the polarizing plate of the present invention. FIG. 1B is a cross-sectional view showing the configuration of the polarizing plate of the present invention. FIG. 2 is a perspective view showing the configuration of the liquid crystal display device of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Protective film 1a Protective film 1b Protective film 2 Polarizer 3 Functional optical film 4 Adhesive layer 11 Upper polarizing plate 12 Upper polarizing plate absorption axis 13 Upper optical anisotropic layer 14 Upper optical anisotropic layer orientation control direction 15 Liquid crystal cell Upper substrate 16 Upper substrate alignment control direction 17 Liquid crystal molecule 18 Liquid crystal cell lower substrate 19 Lower substrate alignment control direction 20 Lower optical anisotropic layer 21 Lower optical anisotropic layer alignment control direction 22 Lower side polarizing plate 23 Lower polarization Plate absorption axis

Claims (10)

The polarizing plate formed by laminating the first protective film, the polarizer, and the second protective film in this order, and the moisture permeability of the first protective film at 60 ° C. relative humidity of 95% is 300 g / m ² · day or less, and the second protective film is a cellulose acylate film. The polarizing plate according to claim 1, wherein the moisture permeability of the first protective film is 50 g / m ² · day or less.   The absolute value of the difference between the in-plane direction retardation value (Re10) at 25 ° C. relative humidity of 10% and the in-plane direction retardation value (Re80) at 25 ° C. relative humidity of 80% of the second protective film, The polarizing plate according to claim 1, wherein a value Gr divided by an in-plane retardation value (Re60) at 25 ° C. and a relative humidity of 60% is 0.06 or more. The polarizing plate according to claim 1, wherein the second protective film satisfies the following formulas (I) and (II).
2.30 ≦ SA + SB <2.80 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Formula (I)
0 ≦ SB ≦ 1.00 ···································· Formula
In the above formulas (I) and (II), SA and SB represent the substitution degree of the acyl group substituted with the hydroxyl group of cellulose, SA represents the substitution degree of the acetyl group, and SB has 3 to 4 carbon atoms. Represents the substitution degree of the acyl group. The second protective film is stretched, and the retardation value Re in the in-plane direction defined by the following formula (III) is in the range of 20 to 70 nm, and the thickness direction is defined by the following formula (IV). The retardation value Rth of the polarizing plate according to claim 1, which has a retardation value Rth in the range of 30 to 400 nm.
Re = (nx−ny) × d... Formula (III)
Rth = {(nx + ny) / 2−nz} × d... Formula (IV)
In the above formulas (III) and (IV), nx is the refractive index in the slow axis direction in the film plane, ny is the refractive index in the fast axis direction in the film plane, and nz is the film refractive index. It is the refractive index in the thickness direction, and d is the thickness of the film. The polarizing plate according to claim 1, wherein Re and Rth of the second protective film are cellulose acylate films satisfying the following formulas (V) and (VI).
｜ Re | ≦ 10 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Formula (V)
｜ Rth | ≦ 25 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Formula (VI)   The polarizing plate according to claim 1, wherein the first protective film is a cycloolefin resin film.   The polarizing plate according to claim 1, wherein at least one of a hard coat layer and an antireflection layer is provided on the first protective film.   A liquid crystal display device having a liquid crystal cell and two polarizing plates disposed on both sides thereof, wherein at least one polarizing plate is the polarizing plate according to claim 1, and the polarizing plate A liquid crystal display device, wherein the second protective film is bonded to the side facing the liquid crystal cell.   The liquid crystal display device according to claim 9, wherein the liquid crystal cell is at least one of a VA mode and an IPS mode.