KR101431292B1 - Ips mode liquid crystal display apparatus and process for manufacturing the same - Google Patents

Abstract

The present invention provides an IPS type liquid crystal display device and a method of manufacturing an IPS type liquid crystal display device in which color shifts over time are improved. This IPS type liquid crystal display device is an IPS type liquid crystal display device having an IPS type liquid crystal glass cell and two polarizing plates bonded on both sides of the liquid crystal glass cell for IPS with an adhesive layer interposed therebetween. At least one of the two polarizing plates The polarizing plate comprises a polarizer and two polarizing plate protective films bonded to both surfaces of the polarizer, and has a total film thickness of 80 to 150 占 퐉 and a stiffness (ST) at 23 占 폚 and 55% RH of 20 to 80 (g) Wherein Ro of the polarizing plate protective film on the side sandwiched between the IPS liquid crystal glass cell and the polarizer of the two polarizing plate protective films of the polarizing plate is 0? Ro? 5 nm, Rt is -5? Rt? 5 nm, And a film thickness of 20 to 60 mu m.

IPS type liquid crystal display, liquid crystal glass cell for IPS, polarizer, polarizer protective film

Description

TECHNICAL FIELD [0001] The present invention relates to an IPS type liquid crystal display device and a method of manufacturing an IPS type liquid crystal display device,

The present invention relates to an IPS type liquid crystal display device and a method of manufacturing an IPS type liquid crystal display device.

In a liquid crystal display device having an in-plane switching (IPS) type liquid crystal cell, liquid crystal molecules aligned in one direction in a substantially horizontal direction in an electric field free state are rotated about 45 degrees by application of an electric field in a lateral direction, Display) and shielding (black display) (refer to Patent Document 1 below).

In a liquid crystal display device provided with an IPS type liquid crystal glass cell, when a screen is viewed in an oblique direction at an angle of 45 degrees with respect to an absorption axis of the polarizing plate (azimuth angle of 45 degrees, 135 degrees, 225 degrees, 315 degrees) (Also referred to as a color shift) in which the display color varies depending on the viewing angle.

For this reason, in the non-patent reference 1, a cellulose ester film in which Ro and Rt are set to zero substantially without using a retardation film is used as the polarizing plate protective film between the polarizers sandwiching the liquid crystal glass cell and the liquid crystal glass cell And a method of making it better by using it.

On the other hand, in the IPS type liquid crystal display apparatus on the large screen, new problems such as color shift due to improvement of the pressure sensitive adhesive used when the polarizing plate is adhered to the liquid crystal glass cell have been caused.

This phenomenon is attributed to the use of a stronger pressure-sensitive adhesive due to the large screen, and as a result, the stress is adhered to the polarizing plate protective film positioned between the glass cell of the polarizing plate and the polarizer, It was found that the change occurred due to the change of the temperature.

Patent Document 1: Japanese Patent No. 2982869

Non-Patent Document 1: Hajime Nakayama et al. (FUJI PHOTO FILM Co., Ltd.) IDW / AD '05 p1317-1320

DISCLOSURE OF THE INVENTION <

[PROBLEMS TO BE SOLVED BY THE INVENTION]

An object of the present invention is to provide an IPS type liquid crystal display device and an IPS type liquid crystal display device with improved color shift over time.

MEANS FOR SOLVING THE PROBLEMS [

Means for Solving the Problems As a result of intensive investigations to solve the above problems, the present inventors have found that the above objects can be achieved by a polarizing plate, a liquid crystal display device and a liquid crystal display device manufacturing method as described below, and accomplished the present invention.

The above object of the present invention can be achieved by the following arrangement.

(1) An IPS type liquid crystal display device having an IPS type liquid crystal glass cell and two polarizing plates adhered to both sides of the liquid crystal glass cell for IPS with an adhesive layer interposed therebetween,

Wherein at least one of the two polarizing plates comprises a polarizer and two polarizing plate protective films joined to both sides of the polarizing element,

The total film thickness is 80 to 150 mu m,

A stiffness (ST) of 20 to 80 (g) at 23 占 폚 and 55% RH,

Wherein Ro of the polarizing plate protective film on the side sandwiched between the IPS liquid crystal glass cell and the polarizer among the two polarizing plate protective films of the polarizing plate is 0? Ro? 5 nm, Rt is -5? Rt? 5 nm, 20 to 60 占 퐉.

Ro = (nx-ny) xd

Rt = {(nx + ny) / 2-nz} xd

(Where nx represents the refractive index in the in-plane slow axis direction, ny represents the refractive index in the direction perpendicular to the slow axis, nz represents the refractive index in the film thickness direction, and d represents the film thickness (nm)

(2) The IPS liquid crystal display device according to (1), wherein the total film thickness of the at least one polarizing plate is 80 to 140 m.

(3) The IPS liquid crystal display device according to (1) or (2), wherein at least one of the two polarizing plate protective films is made of cellulose ester.

(4) The IPS liquid crystal display device according to (3), wherein the polarizing plate protective film made of the cellulose ester is a cellulose ester film containing a compound having negative directional birefringence.

(5) A method of manufacturing an IPS-type liquid crystal display device in which two polarizing plates are bonded to both sides of an IPS-type liquid crystal glass cell via an adhesive layer,

Wherein at least one of the two polarizing plates comprises a polarizer and two polarizing plate protective films joined to both sides of the polarizing element,

The total film thickness is 80 to 150 mu m,

A stiffness (ST) of 20 to 80 (g) at 23 占 폚 and 55% RH,

Wherein Ro of the polarizing plate protective film on the side sandwiched between the IPS liquid crystal glass cell and the polarizer among the two polarizing plate protective films of the polarizing plate is 0? Ro? 5 nm, Rt is -5? Rt? 5 nm, 20 to 60 占 퐉.

&Lt; EMI ID =

Ro = (nx-ny) xd

&Lt; EMI ID =

Rt = {(nx + ny) / 2-nz} xd

(Where nx represents the refractive index in the in-plane slow axis direction, ny represents the refractive index in the direction perpendicular to the slow axis, nz represents the refractive index in the film thickness direction, and d represents the film thickness (nm)

(6) The method of manufacturing an IPS liquid crystal display device according to (5), wherein the total film thickness of the at least one polarizing plate is 80 to 140 m.

EFFECTS OF THE INVENTION [

In the IPS-type liquid crystal display device according to the present invention, it is possible to improve the color shift over time caused by the step of bonding the polarizing plate. A new problem that has not become a problem in the processes up to now is that a large change is caused by the large screen of the liquid crystal display device and the fact that the polarizing plate protective film is used in a region where the original retardations Ro and Rt are substantially zero, I think.

1 is a schematic view of a liquid crystal display device according to a preferred embodiment of the present invention.

Explanation of symbols

1: polarizer protective film

2: Polarizer

3: Protective film for non-polarized polarizing plate

4: Non-electromotive cell glass substrate

5: IPS type liquid crystal layer

6: Electrode-side cell glass substrate (electrode is formed on the substrate)

7: Polarizing plate protective film on the electrode side

8: Polarizer

9: Polarizing plate protective film

10: Non-polarized-side polarizing plate

11: IPS type liquid crystal cell

12: Electrode-side polarizing plate (polarizing plate of the present invention)

13: prism sheet

14:

15: Backlight

BEST MODE FOR CARRYING OUT THE INVENTION [

Hereinafter, the best mode for carrying out the present invention will be described in detail, but the present invention is not limited thereto.

(Stiffness of the polarizer)

At least one of the two polarizers used in the liquid crystal display of the present invention is characterized in that the stiffness (ST) at 23 DEG C and 55% RH is in the range of 20 to 80 (g). Here, the stiffness is an average value in the absorption axis direction and the transmission axis direction of the polarizing plate. When the rigidity is out of the range of 20 g to 80 g, the improvement of the color shift is not sufficient. More preferably in the range of 30 to 80 g, and particularly preferably in the range of 35 to 80 g.

The measurement method of the stiffness of the polarizing plate at 23 DEG C and 55% RH is as follows.

<Measurement of Rigidity>

The polarizing plate is cut into a width of 35 mm and a length of 105 mm, and both ends are fixed with a double-sided tape having a width of 5 mm, and a loop is made in a portion having a length of 100 mm. The load (g) when the ring was pushed in 10 mm was read into the load cell to make the rigidity. At this time, the measurement environment was maintained at 23 DEG C and 55% RH.

<Adjustment of rigidity>

The stiffness of the present invention can be adjusted by adjusting the thickness and the like of the polarizing plate protective film and the polarizer, and can be adjusted depending on the kind, amount, and the like of the specific compound to be contained in the polarizing plate protective film.

Specific compounds include compounds having negative orientation birefringence. The kind and amount of the compound having a negative orientation birefringence are determined in relation to the retardation.

The total film thickness of the polarizing plate is 80 to 150 占 퐉, preferably 80 to 140 占 퐉, and more preferably 90 to 120 占 퐉. The total film thickness of the polarizing plate includes a polarizer, a polarizing plate protective film bonded to both surfaces of the polarizing film, and a pressure sensitive adhesive for bonding the polarizing plate and the polarizing plate protective film.

(Polarizing plate protective film on the side sandwiched between the liquid crystal glass cell and the polarizer)

The polarizing plate protective film on the side sandwiched between the liquid crystal glass cell and the polarizer of the present invention has Ro of 0 to 5 nm and Rt of -5 to 5 nm, preferably Ro of 0 to 2 nm. As a means for reducing the values of Ro and Rt, it is preferable that the cellulose ester film can be adjusted by containing a compound having a negative directional birefringence, and the film thickness of the cellulose ester film is preferably 20 to 60 탆 . It is preferable that the polarizing plate having the film thickness and the retardation (hereinafter referred to as the polarizing plate of the present invention) is disposed on the electrode side of the liquid crystal glass cell.

It is preferable that the polarizing plate protective film at this position is uniform as a film. For example, even if a plurality of films are overlapped or a coating layer is provided to have the same Ro and Rt, Is large.

<Cellulose Ester>

Examples of the cellulose ester forming the polarizing plate protective film used in the present invention include triacetylcellulose (TAC), diacetylcellulose (DAC), cellulose acetate propionate (CAP), cellulose acetate butyrate (CAB), cellulose acetate phthalate, cellulose And cellulose esters such as acetate trimellitate and cellulose nitrate.

The cellulose used as the raw material of the cellulose ester used in the present invention is not particularly limited, but examples thereof include cotton linter, wood pulp and kenaf. Each of the cellulose esters obtained therefrom can be used singly or in any ratio, and it is preferable to use 50 wt% or more of cotton linter.

When the molecular weight of the cellulose ester film is large, the elastic modulus is increased. However, if the molecular weight is excessively increased, the viscosity of the solution of the cellulose ester becomes too high, and the productivity is lowered. The number average molecular weight (Mn) of the cellulose ester is preferably 30,000 to 200,000, more preferably 50,000 to 200,000.

The cellulose ester used in the present invention preferably has an Mw / Mn ratio of 1 to 5, more preferably 1 to 3, and particularly preferably 1.4 to 2.3.

Since the average molecular weight and the molecular weight distribution of the cellulose ester can be measured by high performance liquid chromatography, the number average molecular weight (Mn) and the mass average molecular weight (Mw) can be calculated and the ratio can be calculated.

The measurement conditions are as follows.

Solvent: methylene chloride

Column: Shodex K806, K805, K803G (manufactured by Showa Denko K.K.) were connected and used)

Column temperature: 25 ° C

Sample concentration: 0.1 mass%

Detector: RI Model 504 (manufactured by GL Science)

Pump: L6000 (manufactured by Hitachi Seisakusho Co., Ltd.)

Flow rate: 1.0 ml / min

Calibration curve: Standard polystyrene STK A calibration curve of 13 samples with standard polystyrene (manufactured by Tosoh Corporation) Mw = 1,000,000 to 500 was used. The 13 samples are preferably used at substantially equal intervals.

Particularly preferred cellulose esters are represented by the following formulas (I) and (II) when an acyl group having 2 to 4 carbon atoms is used as a substituent, the substitution degree of the acetyl group is Xac and the substitution degree of the propionyl group or the butyryl group is Ypb At the same time, it is a satisfactory cellulose ester.

2.2? (Xac + Ypb)? 2.95

0 &lt; Xac <

The substitution degree of these acyl groups can be measured according to the method defined in ASTM-D817-96. The part not substituted with an acyl group usually exists as a hydroxyl group. These cellulose esters can be synthesized by a known method.

(Compound having negative orientation birefringence)

In the present invention, the presence of a compound having a negative orientation birefringence is determined in relation to Ro, Rt and rigidity.

The compound having negative oriented birefringence of the present invention means a material exhibiting negative birefringence with respect to the stretching direction of the film in the cellulose ester film and is preferably an acrylic polymer, a polyester, a furanose structure or a pyranose structure , A sulfone compound, and the like.

Whether or not the film has negative orientation birefringence can be found by measuring the birefringence of a film in a system to which the compound is not added by a birefringence meter and comparing the difference.

<Compound Having Acrylic Polymer, Polyester, Furanose Structure or Piranose Structure>

Next, the acrylic polymer, polyester and compounds having a furanose structure or a pyranose structure usable in the present invention will be described.

<Acrylic Polymer>

The cellulose ester film of the present invention preferably contains an acrylic polymer having a weight average molecular weight ranging from 500 to 30000, which exhibits negative directional birefringence with respect to the stretching direction. The acrylic polymer is preferably an acrylic polymer having an aromatic ring in the side chain or a cyclohexyl And is preferably an acrylic polymer having a practical group in its side chain.

The polymer has a weight average molecular weight of 500 or more and 30,000 or less, whereby the compatibility of the cellulose ester and the polymer can be improved by controlling the composition of the polymer.

In particular, when the weight average molecular weight of the acrylic polymer having an aromatic ring on the side chain or the acrylic polymer having a cyclohexyl group on the side chain is preferably 500 or more and 10000 or less, transparency of the cellulose ester film after film formation is preferably And exhibits excellent performance as a protective film for a polarizing plate.

Since the polymer has a weight average molecular weight of 500 or more and 30,000 or less, it is considered that oligomers are present between low molecular weight polymers. In order to synthesize such a polymer, it is preferable to use a method which makes it possible to make the molecular weight as uniform as possible by a method that does not excessively adjust the molecular weight and does not excessively increase the molecular weight.

Examples of such a polymerization method include a method of using a peroxide polymerization initiator such as cumene peroxide or t-butyl hydroperoxide, a method of using a polymerization initiator in a larger amount than usual polymerization, a method of using a mercapto compound or a chain transfer agent such as carbon tetrachloride A method of using a polymerization terminator such as benzoquinone or dinitrobenzene in addition to the polymerization initiator, a method of using a thiol group such as those disclosed in Japanese Patent Application Laid-Open Nos. 2000-128911 or 2000-344823, , Or a method in which bulk polymerization is carried out by using a polymerization catalyst in which the above compound and an organometallic compound are used in combination, and the like are all preferably used in the present invention, but the method described in the above publication is particularly preferable .

Monomers as monomer units constituting the polymer useful in the present invention are illustrated below, but are not limited thereto.

Examples of the ethylenically unsaturated monomer unit constituting the polymer obtained by polymerizing the ethylenically unsaturated monomer include: vinyl esters such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl valerate, vinyl pivalate, vinyl caprate, capric acid But are not limited to, vinyl, vinyl laurate, vinyl myristate, vinyl palmitate, vinyl stearate, vinyl cyclohexanecarboxylate, vinyl octylate, vinyl methacrylate, vinyl crotonate, vinyl sorbate, vinyl benzoate, Vinyl or the like; Examples of the acrylic ester include acrylic acid esters such as methyl acrylate, ethyl acrylate, propyl acrylate (i-, n-), butyl acrylate (n-, i-, s-, t-), pentyl acrylate ), Hexyl acrylate (n- and i-), heptyl acrylate (n- and i-), octyl acrylate (n- and i-), nonyl acrylate (n- and i-) and myristyl acrylate Acrylic acid (2-hydroxypropyl), acrylic acid (2-hydroxypropyl), acrylic acid (2-ethylhexyl acrylate), phenethyl acrylate 3-hydroxypropyl), acrylic acid (4-hydroxybutyl), acrylic acid (2-hydroxybutyl), acrylic acid-p-hydroxymethylphenyl, acrylic acid-p- (2-hydroxyethyl) phenyl and the like; A methacrylic acid ester as the methacrylic acid ester; Examples of the unsaturated acid include acrylic acid, methacrylic acid, maleic anhydride, crotonic acid, itaconic acid, and the like. The polymer composed of the monomer may be a copolymer or a homopolymer, and a homopolymer of a vinyl ester, a copolymer of a vinyl ester, and a copolymer of a vinyl ester and an acrylic acid or a methacrylic acid ester are preferable.

In the present invention, an acrylic polymer (simply referred to as an acrylic polymer) refers to a homopolymer or copolymer of acrylic acid or methacrylic acid alkyl ester having no monomer unit having an aromatic ring or cyclohexyl group. The acrylic polymer having an aromatic ring in the side chain is an acrylic polymer containing an acrylic acid or methacrylic acid ester monomer unit having an aromatic ring.

The acrylic polymer having a cyclohexyl group in the side chain is an acrylic polymer containing an acrylic acid or methacrylic acid ester monomer unit having a cyclohexyl group.

Examples of the acrylic acid ester monomer having no aromatic ring and cyclohexyl group include methyl acrylate, ethyl acrylate, propyl acrylate (i-, n-), butyl acrylate (n-, i-, s-, (N-, i-, and n-butyl acrylate), pentyl (n-, i-, and s-), hexyl Acrylic acid (2-hydroxypropyl), acrylic acid (2-hydroxypropyl), acrylic acid (2-ethylhexyl acrylate) 3-hydroxypropyl), acrylic acid (4-hydroxybutyl), acrylic acid (2-hydroxybutyl), acrylic acid (2-methoxyethyl), acrylic acid (2-ethoxyethyl) Lt; / RTI &gt; ester.

The acrylic polymer is a homopolymer or a copolymer of the above monomers, but preferably contains 30 mass% or more of acrylic acid methyl ester monomer units, and more preferably 40 mass% or more of methacrylic acid methyl ester monomer units. In particular, a homopolymer of methyl acrylate or methyl methacrylate is preferred.

Examples of the acrylic acid or methacrylic acid ester monomer having an aromatic ring include phenyl acrylate, phenyl methacrylate, acrylic acid (2 or 4-chlorophenyl), methacrylic acid (2 or 4-chlorophenyl) (O- or m- or p-tolyl), methacrylic acid (o- or m- or p-tolyl (methoxycarbonylphenyl) Benzyl acrylate, benzyl acrylate, benzyl acrylate, phenethyl acrylate, and phenetyl methacrylate are preferable, although benzyl acrylate, benzyl methacrylate, phenethyl acrylate, phenethyl methacrylate, phenethyl methacrylate and phenethyl acrylate Can be used.

Among the acrylic polymers having an aromatic ring in the side chain, it is preferable to have 20 to 40 mass% of acrylic acid or methacrylic acid ester monomer units having an aromatic ring and 50 to 80 mass% of acrylic acid or methacrylic acid methyl ester monomer units . It is preferable that the polymer contains 2 to 20 mass% of acrylic acid or methacrylic acid ester monomer unit having a hydroxyl group.

Examples of the acrylic ester monomer having a cyclohexyl group include cyclohexyl acrylate, cyclohexyl acrylate, cyclohexyl methacrylate, acrylic acid (4-methylcyclohexyl), methacrylic acid (4-methylcyclohexyl) ), And methacrylic acid (4-ethylcyclohexyl). Of these, cyclohexyl acrylate and cyclohexyl methacrylate can be preferably used.

Among the acrylic polymers having a cyclohexyl group in the side chain, it is preferable to have 20 to 40 mass% and 50 to 80 mass% of acrylic acid or methacrylic acid ester monomer units having a cyclohexyl group. It is also preferable that the polymer contains 2 to 20% by mass of acrylic acid or methacrylic acid ester monomer units having a hydroxyl group.

A polymer obtained by polymerizing the ethylenically unsaturated monomer, an acrylic polymer, an acrylic polymer having an aromatic ring in the side chain, and an acrylic polymer having a cyclohexyl group in the side chain are all excellent in compatibility with a cellulose resin.

In the case of these acrylic acid or methacrylic acid ester monomers having a hydroxyl group, it is a constituent unit of a copolymer which is not a homopolymer. In this case, it is preferable that the acrylic acid or methacrylic acid ester monomer unit having a hydroxyl group is contained in an amount of 2 to 20 mass% in the acrylic polymer.

In the present invention, a polymer having a hydroxyl group in the side chain can also be preferably used. The monomer unit having a hydroxyl group is the same as the monomer described above, but acrylic acid or methacrylic acid ester is preferable, and examples thereof include acrylic acid (2-hydroxyethyl), acrylic acid (2-hydroxypropyl) (2-hydroxyethyl) phenyl, or acrylic acid (2-hydroxybutyl), acrylic acid (2-hydroxybutyl), acrylic acid , And preferred examples thereof include 2-hydroxyethyl acrylate and 2-hydroxyethyl methacrylate. The acrylic acid ester or methacrylic acid ester monomer unit having a hydroxyl group in the polymer is preferably contained in the polymer in an amount of 2 to 20 mass%, more preferably 2 to 10 mass%.

The above-mentioned polymer contains not only 2 to 20% by mass of the monomer unit having a hydroxyl group but also excellent compatibility with the cellulose ester, retention property and dimensional stability, and a low moisture permeability, It has an effect that the adhesiveness is particularly excellent and the durability of the polarizing plate is improved.

The method of allowing the acrylic polymer to have a hydroxyl group in at least one end of the main chain is not particularly limited as long as it has a hydroxyl group at the end of the main chain. However, a radical polymerization initiator having a hydroxyl group such as azobis (2-hydroxyethylbutyrate) A method of using a chain transfer agent having a hydroxyl group such as 2-mercaptoethanol, a method of using a polymerization terminator having a hydroxyl group, a method of having a hydroxyl group at a terminal by living ion polymerization, 128911 or 2000-344823, or a method in which bulk polymerization is carried out by using a polymerization catalyst comprising a compound having one thiol group and a secondary hydroxyl group as described in JP-A No. 2000-344823 or a combination of the above compound and an organometallic compound, Particularly, the method described in the above publication is preferable.

The polymer produced by the method related to this publication is commercially available as an Actflow series manufactured by Soken Chemical Industries, Ltd., and can be preferably used. The polymer having a hydroxyl group at the terminal and / or the polymer having a hydroxyl group at the side chain have the effect of significantly improving the compatibility and transparency of the polymer in the present invention.

In addition, a polymer using styrene as the ethylenic unsaturated monomer exhibiting negative orientation birefringence with respect to the stretching direction is preferable because it exhibits negative refractivity. Examples of the styrene include styrene, methylstyrene, dimethylstyrene, trimethylstyrene, ethylstyrene, isopropylstyrene, chloromethylstyrene, methoxystyrene, acetoxystyrene, chlorostyrene, dichlorostyrene, bromostyrene, methyl vinylbenzoate Ester, and the like, but are not limited thereto.

The unsaturated ethylenic monomer may be copolymerized with an exemplary monomer, and two or more kinds of the above polymers may be used in common in cellulose esters for the purpose of controlling birefringence.

The cellulose ester film according to the present invention is a cellulose ester film obtained by copolymerizing an ethylenically unsaturated monomer Xa having no aromatic ring and a hydrophilic group in the molecule with an ethylenically unsaturated monomer Xb having no aromatic ring in the molecule and having a hydrophilic group and having a weight average molecular weight of 5000 to 30000 And polymer Y having a weight-average molecular weight of 500 or more and 3,000 or less, obtained by polymerizing the following polymer X and, more preferably, the ethylenically unsaturated monomer Ya having no aromatic ring.

<Polymer X, Polymer Y>

Polymer X of the present invention is a polymer obtained by copolymerizing an ethylenically unsaturated monomer Xa having no aromatic ring and a hydrophilic group in the molecule with an ethylenically unsaturated monomer Xb having no aromatic ring in the molecule and having a hydrophilic group and having a weight average molecular weight of 5000 to 30000. Preferably, Xa is an acrylic or methacrylic monomer having no aromatic ring and a hydrophilic group in the molecule, and Xb is an acrylic or methacrylic monomer having a hydrophilic group without an aromatic ring in the molecule.

Polymer X of the present invention is represented by the following general formula (1).

- (Xa) m- (Xb) n- (Xc) p-

More preferably, it is a polymer represented by the following formula (1a).

- [CH ₂ -C (-R 1) (-CO ₂ R ₂ )] m- [CH ₂ -C (-R 3) (-CO ₂ R 4 -OH)

(Wherein R 1 and R ₃ represent H or CH ₃ , R ₂ represents an alkyl group or a cycloalkyl group having 1 to 12 carbon atoms, R ⁴ represents -CH ₂ -, -C ₂ H ₄ - or -C ₃ H ₆ - M, n and p represent molar composition ratios, with m ≠ 0, n ≠ 0, and m + n + p = 100), Xc represents a polymerizable monomer unit for Xa and Xb,

Examples of the monomer as the monomer unit constituting the polymer X of the present invention include, but are not limited to, the following.

In X, the hydrophilic group means a group having a hydroxyl group or an ethylene oxide chain.

Examples of the ethylenically unsaturated monomer Xa having no aromatic ring and a hydrophilic group in the molecule include methyl acrylate, ethyl acrylate, propyl acrylate (i-, n-), butyl acrylate (n-, i-, s-, (N-, i-), acrylate (n-, i-, s-), hexyl acrylate (n-, i-), heptyl acrylate -, myristyl acrylate (n-, i-), acrylic acid (2-ethylhexyl), acrylic acid (epsilon -caprolactone), acrylic acid (2-ethoxyethyl), or the above acrylic acid ester as methacrylic acid ester What is changed. Among them, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate and propyl methacrylate (i-, n-) are preferable.

The ethylenically unsaturated monomer Xb which does not have an aromatic ring in the molecule and has a hydrophilic group is preferably acrylic acid or methacrylic acid ester as a monomer unit having a hydroxyl group, and examples thereof include acrylic acid (2-hydroxyethyl), acrylic acid Hydroxypropyl), acrylic acid (4-hydroxybutyl), acrylic acid (2-hydroxybutyl), or those obtained by substituting acrylic acid with methacrylic acid, preferably acrylic acid (2-hydroxyethyl) and methacrylic acid (2-hydroxyethyl), acrylic acid (2-hydroxypropyl), and acrylic acid (3-hydroxypropyl).

Xc is not particularly limited as long as it is an ethylenically unsaturated monomer other than Xa and Xb and copolymerizable therewith, but preferably has no aromatic ring.

The molar composition ratio m: n of Xa, Xb and Xc is preferably in the range of 99: 1 to 65:35, and more preferably in the range of 95: 5 to 75:25. And p in Xc is 0 to 10. Xc may be a plurality of monomer units.

When the molar composition ratio of Xa is large, the compatibility with the cellulose ester is improved, but the retardation value Rt in the film thickness direction is increased. If the molar composition ratio of Xb is large, the compatibility is poor, but the effect of reducing Rt is high. If the molar composition ratio of Xb exceeds the above range, haze tends to be generated at the time of film formation, and it is preferable to determine the molar composition ratio of Xa and Xb by optimizing these.

The polymer X has a weight average molecular weight of 5,000 or more and 30,000 or less, and more preferably 8,000 or more and 25,000 or less.

By setting the weight average molecular weight to 5,000 or more, it is preferable that the cellulose ester film has a small dimensional change under high temperature and high humidity, and the polarizing plate protective film has less curling. When the weight average molecular weight is set to 30,000 or less, compatibility with the cellulose ester is further improved, bleeding out under high temperature and high humidity, and further, generation of haze immediately after the film formation are suppressed.

The weight average molecular weight of the polymer X of the present invention can be adjusted by a known molecular weight control method. Examples of such a molecular weight control method include a method of adding a chain transfer agent such as carbon tetrachloride, lauryl mercaptan, and octyl thioglycolate. The polymerization temperature is usually from room temperature to 130 占 폚, preferably from 50 占 폚 to 100 占 폚, but this can be done by adjusting the temperature or the polymerization reaction time.

The weight average molecular weight can be measured by the following method.

(Method for measuring weight average molecular weight)

The weight average molecular weight Mw was measured by gel permeation chromatography.

The measurement conditions are as follows.

Solvent: methylene chloride

Column: Shodex K806, K805, K803G (manufactured by Showa Denko K.K.) were connected and used)

Column temperature: 25 ° C

Sample concentration: 0.1 mass%

Detector: RI Model 504 (manufactured by GL Science)

Pump: L6000 (manufactured by Hitachi Seisakusho Co., Ltd.)

Flow rate: 1.0 ml / min

Calibration curve: Standard curve of polystyrene STK Standard polystyrene (manufactured by TOSOH CORPORATION) Calibration curves of 13 samples ranging from Mw = 1000000 to 500 were used. 13 samples are used at almost equal intervals.

Polymer Y of the present invention is a polymer obtained by polymerizing an ethylenically unsaturated monomer Ya having no aromatic ring and having a weight average molecular weight of 500 or more and 3000 or less.

When the weight average molecular weight is 500 or more, the residual monomers of the polymer are reduced, which is preferable. Further, it is preferable to set it to 3000 or less because the retardation value Rt lowering performance is maintained.

Ya is preferably an acrylic or methacrylic monomer having no aromatic ring.

Polymer Y of the present invention is represented by the following formula (2).

- (Ya) k- (Yb) q-

More preferably, it is a polymer represented by the following formula (2a).

- [CH ₂ -C (-R 5) (-CO ₂ R 6)] k- [Yb] q-

(Wherein, R5 is H or CH _3, R6 represents an alkyl group or a cycloalkyl group having a carbon number of 1 to 12, Yb denotes the Ya and the copolymerizable monomer units, k and q represent a molar ratio, provided that k 0 &lt; / RTI &gt; and k + q = 100)

Yb is not particularly limited as long as it is an ethylenically unsaturated monomer copolymerizable with Ya. Yb may be plural. k + q = 100, and q is preferably 0 to 30.

The ethylenically unsaturated monomer Ya constituting the polymer Y obtained by polymerizing an ethylenically unsaturated monomer having no aromatic ring is preferably an acrylic acid ester such as methyl acrylate, ethyl acrylate, propyl acrylate (i-, n-), butyl acrylate (n-, i-, s-, t-), pentyl acrylate (n-, i-, s-), hexyl acrylate (n-, i-), heptyl acrylate acrylic acid (epsilon -caprolactone), acrylic acid (2-ethylhexyl acrylate), acrylic acid (2-ethylhexyl acrylate) (2-hydroxypropyl), acrylic acid (3-hydroxypropyl), acrylic acid (4-hydroxybutyl), acrylic acid (2-hydroxybutyl), methacrylic acid ester With methacrylic acid ester; Examples of the unsaturated acid include acrylic acid, methacrylic acid, maleic anhydride, crotonic acid, itaconic acid, and the like.

Yb is not particularly limited as long as it is an ethylenically unsaturated monomer copolymerizable with Ya, and examples thereof include vinyl acetate such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl valerate, vinyl pivalate, vinyl caprate, Vinyl laurate, vinyl myristate, vinyl palmitate, vinyl stearate, vinyl cyclohexanecarboxylate, vinyl octylate, vinyl methacrylate, vinyl crotonate, vinyl sorbate and vinyl cinnamate are preferable . Yb may be plural.

In order to synthesize the polymers X and Y, it is preferable to use a method which makes it possible to make the molecular weight as uniform as possible by a method which does not adjust the molecular weight normally and does not excessively increase the molecular weight. Examples of such a polymerization method include a method of using a peroxide polymerization initiator such as cumene peroxide or t-butyl hydroperoxide, a method of using a polymerization initiator in a larger amount than usual polymerization, a method of using a mercaptan compound or a chain transfer agent such as carbon tetrachloride , A method of using a polymerization terminator such as benzoquinone or dinitrobenzene in addition to the polymerization initiator, a method of using a thiol group such as that disclosed in Japanese Patent Application Laid-Open Nos. 2000-128911 or 2000-344823, , Or a method in which bulk polymerization is carried out using a polymerization catalyst in which the above compound and an organometallic compound are used in combination, and the like are all preferably used in the present invention. In particular, a method in which a thiol group and a secondary hydroxyl group Is used as a chain transfer agent.

In this case, the ends of the polymer X and the polymer Y have a hydroxyl group and a thioether due to a polymerization catalyst and a chain transfer agent. This terminal residue can adjust the compatibility of the polymers X and Y with the cellulose ester.

The hydroxyl groups of the polymers X and Y are preferably 30 to 150 mgKOH / g.

(Method for measuring hydroxyl value)

This measurement conforms to JIS K 0070 (1992). This hydroxyl value is defined as the number of mg of potassium hydroxide required to neutralize the acetic acid bound to the hydroxyl group when 1 g of the sample is acetylated. Specifically, sample Xg (about 1 g) is accurately weighed into a flask, and 20 ml of an acetylation reagent (prepared by adding pyridine to 20 ml of acetic anhydride to make 400 ml) is added accurately. The flask inlet is equipped with an air cooling tube and heated in a glycerin bath at 95-100 ° C. After 1 hour and 30 minutes, it is cooled, 1 ml of purified water is added from an air cooling tube, and acetic anhydride is decomposed with acetic acid. Next, titration is carried out with a 0.5 mol / L potassium hydroxide ethanol solution using a potentiometric titration apparatus, and the inflection point of the obtained titration curve is set as an end point. Further, as the blank test, the sample is titrated without adding the sample to obtain the inflection point of the titration curve.

The hydroxyl value is calculated by the following formula.

(B-C) x f x 28.05 / X} + D

(B) is the amount (ml) of the 0.5 mol / L potassium hydroxide ethanol solution used in the blank test, C is the amount (ml) of the 0.5 mol / L potassium hydroxide ethanol solution used for titration, f is 0.5 mol / Concentration coefficient of potassium hydroxide ethanol solution, D represents acid value, and 28.05 represents 1/2 of 56.11 of 1 mol of potassium hydroxide)

All of the polymer X and the polymer Y described above are excellent in compatibility with the cellulose ester, are excellent in productivity without evaporation or volatilization, have good retention as a protective film for a polarizing plate, have a low moisture permeability and excellent dimensional stability.

The content of the polymer X and the polymer Y in the cellulose ester film is preferably in a range satisfying the following formulas (i) and (ii). When the content of the polymer X is Xg (mass% = mass of polymer X / mass of cellulose ester 100) and the content of polymer Y is Yg (mass%),

(I) 5? Xg + Yg? 35 (mass%)

(Ii) 0.05? Yg / (Xg + Yg)? 0.4

The preferable range of the formula (i) is 10 to 25 mass%.

When the total amount of the polymer X and the polymer Y is 5% by mass or more, the polymer X and the polymer Y sufficiently function to reduce the retardation value Rt. When the total amount is 35% by mass or less, adhesion with the polarizer PVA is good.

Polymer X and polymer Y can be added directly to a dope prepared by dissolving or directly dissolving cellulose ester in an organic solvent which is used as a material for forming a dope liquid to be described later.

<Polyester>

The cellulose ester film of the present invention preferably contains the following polyester.

(The polyester represented by the general formula (3) or (4)

The cellulose ester film of the present invention preferably contains a polyester represented by the following general formula (3) or (4).

B1- (G-A-) mG-B1

(Wherein B1 represents a monocarboxylic acid, G represents a bivalent alcohol, A represents a dibasic acid, B1, G and A do not all contain an aromatic ring, and m represents a repeating number)

B2- (A-G-) nA-B2

(Wherein B2 represents a monoalcohol, G represents a bivalent alcohol, A represents a dibasic acid, B2, G and A both do not contain an aromatic ring, and n represents a repeating number)

In the formulas (3) and (4), B1 represents a monocarboxylic acid component, B2 represents a monoalcohol component, G represents a bivalent alcohol component, A represents a dibasic acid component, . B1, B2, G, and A do not include an aromatic ring. m and n represent the number of repeats.

The monocarboxylic acid represented by B1 is not particularly limited and known aliphatic monocarboxylic acids and alicyclic monocarboxylic acids can be used.

Examples of preferred monocarboxylic acids include the following, but the present invention is not limited thereto.

As the aliphatic monocarboxylic acid, a linear or branched chain fatty acid having 1 to 32 carbon atoms can be preferably used. More preferably from 1 to 20 carbon atoms, and particularly preferably from 1 to 12 carbon atoms. The addition of acetic acid increases the compatibility with the cellulose ester, and therefore, it is also preferable to use a mixture of acetic acid and other monocarboxylic acids.

Preferred aliphatic monocarboxylic acids include those derived from formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2- ethylhexanecarboxylic acid, undecylic acid, But are not limited to, aliphatic acid, tridecylic acid, tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachic acid, behenic acid, lignoceric acid, Unsaturated fatty acids such as malic acid, melissic acid and lactic acid, and unsaturated fatty acids such as undecylenic acid, oleic acid, sorbic acid, linoleic acid, linolenic acid and arachidonic acid.

The monoalcohol component represented by B2 is not particularly limited and known alcohols can be used. For example, aliphatic saturated alcohols or aliphatic unsaturated alcohols having 1 to 32 carbon atoms and having a straight chain or side chain can be preferably used. More preferably from 1 to 20 carbon atoms, and particularly preferably from 1 to 12 carbon atoms.

Examples of the dihydric alcohol component represented by G include the following, but the present invention is not limited thereto. Examples of the solvent include ethylene glycol, diethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, , Pentanediol, 1,6-hexanediol, 1,5-pentylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol and the like. Of these, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, 1,6-hexanediol, diethylene glycol and triethylene glycol are preferable, and 1 , 3-propylene glycol, 1,4-butylene glycol, 1,6-hexanediol, and diethylene glycol are more preferably used.

The dibasic acid (dicarboxylic acid) component represented by A is preferably an aliphatic dibasic acid or an alicyclic dibasic acid, and examples of the aliphatic dibasic acid include malonic acid, succinic acid, glutaric acid, adipic acid, As the aliphatic dicarboxylic acid, particularly, aliphatic dicarboxylic acids having 4 to 12 carbon atoms and at least one selected from them are used, for example, aliphatic dicarboxylic acids such as malic acid, suberic acid, azelaic acid, sebacic acid, undecandicarboxylic acid and dodecanedicarboxylic acid . That is, two or more kinds of dibasic acids may be used in combination.

m and n represent the number of repeating units, preferably 1 or more and 170 or less.

(The polyester represented by the formula (5) or (6)

The cellulose ester film of the present invention preferably contains a polyester represented by the following general formula (5) or (6).

B1- (G-A-) mG-B1

(Wherein B1 represents a monocarboxylic acid having 1 to 12 carbon atoms, G represents a divalent alcohol having 2 to 12 carbon atoms, A represents a dibasic acid having 2 to 12 carbon atoms, B1, G and A represent All do not include an aromatic ring, and m represents the number of repeats)

B2- (A-G-) nA-B2

(Wherein B2 represents a monohydric alcohol having 1 to 12 carbon atoms, G represents a divalent alcohol having 2 to 12 carbon atoms, A represents a dibasic acid having 2 to 12 carbon atoms, and B2, G, Does not include a ring, and n represents the number of repeats)

In the formulas (5) and (6), B1 represents a monocarboxylic acid component, B2 represents a monoalcohol component, G represents a divalent alcohol component having 2 to 12 carbon atoms, A represents a divalent acid component having 2 to 12 carbon atoms , And shows those synthesized by these. B1, G and A do not all contain an aromatic ring. m and n represent the number of repeats.

B1 and B2 are synonymous with B1 and B2 in the above-described formula (3) or (4).

G and A are an alcohol component or a dibasic acid component having 2 to 12 carbon atoms among G and A in the above-described formula (3) or (4).

The weight average molecular weight of the polyester is preferably 20,000 or less, more preferably 10,000 or less. Particularly, polyester having a weight average molecular weight of 500 to 10000 is preferably used since it has good compatibility with cellulose ester.

The polycondensation of the polyester is carried out by a usual method. For example, a direct reaction between the dibasic acid and a glycol, a dibasic acid or an alkyl ester thereof, for example, a polyester esterification reaction or a ester exchange reaction between a methyl ester of a dibasic acid and a glycol, The condensation can be easily carried out by any one of the condensation method and the dehydrohalogenation reaction of an acid chloride and a glycol of these acids, but it is preferable that the polyester having a weight average molecular weight not so large is obtained by direct reaction.

The polyester having a high distribution on the low molecular weight side has a very good compatibility with the cellulose ester, and after the film formation, the cellulose ester film having a low moisture permeability and a high transparency can be obtained. The method for controlling the molecular weight is not particularly limited and conventional methods can be used. For example, although it depends on the polymerization conditions, it can be adjusted by the amount of these monovalent additions by the method of blocking the molecular terminal with monovalent acid or monovalent alcohol.

In this case, a monovalent acid is preferable in view of the stability of the polymer. For example, acetic acid, propionic acid, butyric acid, and the like can be mentioned. In the polycondensation reaction, however, distillation is not removed from the system but the system is stopped. When the monovalent acid is removed from the reaction system, Can be used. In the case of the direct reaction, the weight average molecular weight can also be controlled by measuring the timing at which the reaction is stopped by the amount of water distilled off during the reaction. In addition, the molar amount of the charged glycol or dibasic acid may be shifted, and the reaction temperature may be adjusted.

The polyester according to the present invention is preferably contained in an amount of 1 to 40 mass% with respect to the cellulose ester, and the polyester represented by the formula (5) or (6) is preferably contained in an amount of 2 to 30 mass%. Particularly preferably 5 to 15% by mass.

&Lt; Compounds having furanose structure or pyranose structure >

The cellulose ester film of the present invention is a cellulose ester film obtained by esterifying all or a part of OH groups in a compound having at least one furanose structure or pyranose structure and having 1 to 12 furanose structures or pyranose structures bound thereto Or a compound thereof.

Examples of the preferable "compound having at least one furanose structure or pyranose structure and having 1 to 12 furanose structures or pyranose structures bound thereto" include, for example, the following compounds The invention is not limited to these.

There may be mentioned, for example, glucose, glucose, mannose, fructose, xylose, arabinose, lactose, sucrose, cellobiose, cellotriose, maltotriose and raffinose. It is preferable to have both the os structure. As an example, sucrose can be mentioned.

The term " compound having at least one furanose structure or pyranose structure of the present invention and esterifying all or part of the OH groups in the compound having 1 to 12 furanose structures or pyranose structures bound thereto " The monocarboxylic acid to be used is not particularly limited, and known aliphatic monocarboxylic acids, alicyclic monocarboxylic acids, aromatic monocarboxylic acids and the like can be used. The carboxylic acid used may be a single kind or a mixture of two or more kinds.

Preferred aliphatic monocarboxylic acids are acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2-ethylhexanecarboxylic acid, But are not limited to, lactic acid, lauric acid, tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachic acid, behenic acid, lignoceric acid, , Unsaturated fatty acids such as melissic acid and lactic acid, and unsaturated fatty acids such as undecylenic acid, oleic acid, sorbic acid, linoleic acid, linolenic acid, arachidonic acid and octenoic acid.

Examples of preferred alicyclic monocarboxylic acids include cyclopentanecarboxylic acid, cyclohexanecarboxylic acid, cyclooctanecarboxylic acid, and derivatives thereof.

Examples of preferred aromatic monocarboxylic acids include those obtained by introducing an alkyl group or an alkoxy group into a benzene ring of a benzoic acid such as benzoic acid or toluic acid, a benzenecarboxylic acid such as cinnamic acid, benzilic acid, biphenylcarboxylic acid, naphthalenecarboxylic acid, An aromatic monocarboxylic acid having two or more benzene rings such as an acid, or derivatives thereof, and benzoic acid is particularly preferable.

Details of methods for producing these compounds are described in Japanese Patent Application Laid-Open Nos. 62-42996 and 10-237084.

Specific examples are given below, but the present invention is not limited thereto.

<Sulfone Compound>

In the general formula (7), R ¹ represents an alkyl group or an aryl group, and R ² and R ³ each independently represent a hydrogen atom, an alkyl group or an aryl group. It is particularly preferable that the total sum of the number of carbon atoms of R ¹ , R ² and R ³ is 10 or more.

In the formula (8), R ⁴ and R ⁵ each independently represent an alkyl group or an aryl group. The total number of carbon atoms of R ⁴ and R ⁵ is 10 or more, and each of the alkyl group and the aryl group may have a substituent. As the substituent, a fluorine atom, an alkyl group, an aryl group, an alkoxy group, a sulfone group and a sulfonamide group are preferable, and an alkyl group, an aryl group, an alkoxy group, a sulfone group and a sulfonamide group are particularly preferable.

The alkyl group may be straight-chain, branched or cyclic, preferably 1 to 25 carbon atoms, more preferably 6 to 25, and 6 to 20 (for example, methyl Isopropyl, isopropyl, butyl, isobutyl, t-butyl, amyl, isoamyl, t-amyl, hexyl, cyclohexyl, heptyl, octyl, bicyclooctyl, nonyl, adamantyl, decyl, , Undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, didecyl) are particularly preferred. As the aryl group, the number of carbon atoms is preferably from 6 to 30, and particularly preferably from 6 to 24 (for example, phenyl, biphenyl, terphenyl, naphthyl, binaphthyl, triphenylphenyl).

Preferable examples of the compound represented by the formula (7) or (8) are shown below, but the present invention is not limited to these specific examples.

(Protective film for non-polarized-side polarizer)

The polarizing plate of the present invention is preferably disposed on the electrode side of the liquid crystal glass cell, but there is no particular limitation on the polarizing plate on the non-polarizing side and the polarizing plate protecting film disposed between the liquid crystal cell and the polarizing plate on the polarizing plate. It is preferable that the polarizing plate protective film has Ro of 0 to 5 nm and Rt of 30 to 80 nm. The thickness of the polarizing plate protective film is preferably 30 to 80 占 퐉, and the total thickness of the polarizing plate is preferably 80 to 180 占 퐉.

The polarizing plate protective film used in the polarizing plate disposed on the non-electrode side of the present invention may be a conventional polarizing plate protective film made of a conventional cellulose ester. It is not always necessary to newly incorporate a phase difference layer and to incorporate a phase difference film. A normally used polarizing plate protective film of 30 to 100 占 퐉 may be used as it is. It is also possible to use the polarizing plate protective film used on the electrode side as it is.

The polarizing plate protective film used in the present invention preferably has a light modulus of elasticity C (590 nm (m ² / N)) of 1.0 × 10 ^-12 to 2.0 × 10 ^-11 .

(Preferable relationship between Ro, Rt and film thickness of the polarizing plate protective film and polarizing plate on the electrode side and the non-polarizing side)

In the polarizing plate protective film on the liquid crystal glass cell side of the polarizing plate used in the present invention, the total of Ro of the protective film on both the electrode side and the non-polarizing side is preferably 0 to 10 nm, more preferably 0 to 5 nm. The total of Rt is preferably from 0 to 85 nm, more preferably from 10 to 60 nm. The thickness of the polarizing plate protective film on the electrode side is preferably 20 to 60 mu m, and the thickness of the polarizing plate protective film on the non-polarizing electrode side is preferably 30 to 100 mu m. In view of the total retardation of the protective films on both the electrode side and the non-positive electrode side, the sum of the film thicknesses of the polarizing plates is preferably 80 to 260 占 퐉, more preferably 50 to 200 占 퐉.

<Other additives>

The cellulose ester film used in the present invention may contain an additive which can be added to a conventional cellulose ester film, in addition to the compound having the negative orientation birefringence.

These additives include plasticizers, ultraviolet absorbers, and fine particles.

The plasticizer that can be used in the present invention is not particularly limited, but it is preferably a polyvalent carboxylic acid ester plasticizer, a glycolate plasticizer, a phthalate ester plasticizer, a fatty acid ester plasticizer and a polyhydric alcohol ester plasticizer, Acrylic plasticizer and the like. Among them, when two or more kinds of plasticizers are used, it is preferable that at least one kind is a polyhydric alcohol ester plasticizer.

The polyhydric alcohol ester plasticizer is preferably a plasticizer containing an ester of a divalent or higher aliphatic polyhydric alcohol and a monocarboxylic acid and having an aromatic ring or a cycloalkyl ring in the molecule. Preferably 2 to 20, aliphatic polyhydric alcohol esters.

The ultraviolet absorber usable in the present invention is intended to improve durability by absorbing ultraviolet rays of 400 nm or less, and particularly preferably has a transmittance at a wavelength of 370 nm of 10% or less, more preferably 5% More preferably, it is 2% or less.

The ultraviolet absorber used in the present invention is not particularly limited, and examples thereof include oxybenzophenone compounds, benzotriazole compounds, salicylic ester compounds, benzophenone compounds, cyanoacrylate compounds, triazine compounds, Based compounds, inorganic powders, and the like. It may be a polymer type ultraviolet absorbent.

Examples of the inorganic particles used in the present invention include inorganic compounds such as silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, Magnesium and calcium phosphate. The fine particles include silicon, which is preferable in that turbidity is low, and silicon dioxide is particularly preferable.

The average particle diameter of the primary particles of the fine particles is preferably from 5 to 50 nm, more preferably from 7 to 20 nm. These are preferably contained mainly as secondary agglomerates having a particle size of 0.05 to 0.3 탆. The content of these fine particles in the cellulose ester film is preferably 0.05 to 1% by mass, more preferably 0.1 to 0.5% by mass. In the case of a multi-layered cellulose ester film by a covalent method, it is preferable that the surface contains fine particles in the added amount.

The fine particles of silicon dioxide are commercially available, for example, under the trade names of Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50 and TT600 (manufactured by Nippon Aerosil Co., Ltd.) , Can be used.

The fine particles of zirconium oxide are commercially available, for example, under the trade names AEROSIL R976 and R811 (manufactured by Nippon Aerosil Co., Ltd.) and can be used.

Examples of the polymer include a silicone resin, a fluororesin, and an acrylic resin. Silicone resins are preferable, and those having a three-dimensional network structure are particularly preferable. For example, Tosal 103, Copper 105, Copper 108, Copper 120, Copper 145, Copper 3120 and Copper 240 (manufactured by Toshiba Silicone Co., Ltd.) It is commercially available under the trade name and can be used.

Among them, Aerosil 200V and Aerosil R972V are particularly preferably used because they have a high effect of lowering the friction coefficient while keeping the turbidity of the cellulose ester film low.

(Rt, Ro measurement method)

In the present invention, Rt and Ro are expressed by Equation (1) and Equation (ii) at a wavelength of 590 nm under 23 캜 and 55% RH.

&Lt; EMI ID =

Ro = (nx-ny) xd

&Lt; EMI ID =

Rt = {(nx + ny) / 2-nz} xd

(Where nx represents the refractive index in the in-plane slow axis direction, ny represents the refractive index in the direction perpendicular to the slow axis, nz represents the refractive index in the film thickness direction, and d represents the film thickness (nm)

The birefringence and retardation value of the film can be measured using an automatic birefringence measurement apparatus (trade name: KOBRA-21ADH, manufactured by Oji Keio Co., Ltd.), but the present invention is not limited thereto.

(Polarizing plate protective film production method)

Next, a method for producing a cellulose ester film for forming a polarizing plate protective film on the electrode side and the non-electrode side of the present invention will be described.

The cellulose ester film according to the present invention is preferably a cellulose ester film produced by a solution casting method or a melt casting method.

The production of the cellulose ester film of the present invention can be carried out by a process comprising the steps of preparing a dope by dissolving a cellulose ester and a compound having a negative orientation birefringence and additives in a solvent, a step of pouring on an endless metal support, A step of drying the dope as a web, a step of peeling off the metal support, a step of stretching or maintaining the width, a step of further drying, and a step of winding the finished film.

The process for producing the dope will be described. The concentration of the cellulose ester in the dope is preferable because the concentration of the cellulose ester in the dope can be reduced to reduce the drying load after being softened to the metal support. However, when the concentration of the cellulose ester is too high, the load during filtration increases and the filtration accuracy deteriorates. The concentration compatible therewith is preferably 10 to 35 mass%, more preferably 15 to 25 mass%.

The solvent to be used in the dope may be used alone or in combination of two or more kinds. However, it is preferable from the viewpoint of production efficiency to use a mixture of a cellulose ester ester and a poor solvent in view of the productivity. In view of solubility of the cellulose ester desirable.

A preferable range of the mixing ratio of the both agent and the poor solvent is 70 to 98% by mass of both the solvent and 2 to 30% by mass of the solvent. As for the two-solvent and the low-solvent, the two solvents in which the cellulose ester to be used is dissolved solely are defined as a poor solvent, and those that are not swollen or dissolved solely are defined as poor solvents.

Therefore, when the average degree of acetalization (substitution degree of acetyl group) of the cellulose ester is changed, the two solvents and the poor solvent are changed. For example, when acetone is used as the solvent, the acetate ester of the cellulose ester (acetyl group substitution degree 2.4) Acetate propionate is a biodegradable agent, and an acetic acid ester of cellulose (acetyl group substitution degree 2.8) becomes a poor solvent.

The two agents used in the present invention are not particularly limited, and examples thereof include organic halogen compounds such as methylene chloride, dioxolanes, acetone, methyl acetate, and methyl acetoacetate. Particularly preferred are methylene chloride or methyl acetate.

In addition, the poor solvent to be used in the present invention is not particularly limited, and for example, methanol, ethanol, n-butanol, cyclohexane, cyclohexanone and the like are preferably used. It is preferable that the dope contains 0.01 to 2% by mass of water. Further, the solvent used for dissolving the cellulose ester is recovered from the film by drying in the film-forming step, and is used by reusing the solvent.

As a method for dissolving cellulose ester in producing the above-described dope, a general method can be used. When heating and pressurization are combined, heating can be performed at a boiling point or more at normal pressure. It is preferable to stir and dissolve the solvent while heating at a temperature in the range where the solvent is not boiled under pressure while the boiling point of the solvent is equal to or higher than the boiling point at the normal pressure to prevent the generation of massive solids called gels or agglomerates. It is also preferable to use a method in which the cellulose ester is mixed with a poor solvent to wet or swell the cellulose ester, followed by further adding a two-component agent to dissolve the cellulose ester. In the present invention, a mixture of two or more of these solvents can be used.

The pressurization can be performed by a method of injecting an inert gas such as nitrogen gas or a method of raising the vapor pressure of the solvent by heating. The heating is preferably performed from the outside, and for example, a jacket type is preferable because the temperature can be easily controlled.

The higher the heating temperature after the addition of the solvent is, the more favorable from the viewpoint of the solubility of the cellulose ester. However, if the heating temperature is too high, the required pressure becomes large and the productivity becomes poor. The heating temperature is preferably 45 to 120 占 폚, more preferably 60 to 110 占 폚, and even more preferably 70 to 105 占 폚. The pressure is also adjusted so that the solvent does not boil at the set temperature.

Alternatively, a cooling dissolution method is also preferably used, whereby the cellulose ester can be dissolved in a solvent such as methyl acetate.

Next, this cellulose ester solution is filtered using a suitable filter medium such as a filter paper. As the filter medium, it is preferable that the absolute filtration accuracy is small in order to remove insolubles and the like. However, if the absolute filtration accuracy is too small, there is a problem that clogging of the filter medium tends to occur. Therefore, a filter material having an absolute filtration accuracy of 0.008 mm or less is preferable, a filter material of 0.001 to 0.008 mm is more preferable, and a filter material of 0.003 to 0.006 mm is more preferable.

The material of the filter medium is not particularly limited and a usual filter material can be used. However, a plastic filter material such as polypropylene or Teflon (registered trademark) or a metal filter material such as stainless steel is preferable because the fibers do not fall off. It is preferable to remove and reduce impurities contained in the raw material cellulose ester, in particular, blotted foreign matter by filtration.

The spots foreign material is a substance in which two polarizing plates are placed in a crossed Nicols state and a roll of cellulose ester is placed therebetween and light is irradiated from the side of one polarizing plate and light from the opposite side leaks when observed from the side of the other polarizing plate (Foreign matter) visible to the user, and it is preferable that the number of wigs having a diameter of 0.01 mm or more is 200 pieces / cm ² or less. More preferably 100 pieces / cm ² or less, still more preferably 50 pieces / m ² or less, and still more preferably 0 to 10 pieces / cm ² or less. It is also preferable that the luminescent viscosity is 0.01 mm or less.

The filtration of the dope can be carried out by a usual method, but a method of filtration while heating the solvent at a temperature within a range in which the solvent is not boiled under pressure at a boiling point of the solvent at normal pressure or more at a normal pressure, It is preferable because the rise is small. The preferred temperature is 45 to 120 占 폚, more preferably 45 to 70 占 폚, and still more preferably 45 to 55 占 폚.

The filtration pressure is preferably small. The filtration pressure is preferably 1.6 MPa or less, more preferably 1.2 MPa or less, and even more preferably 1.0 MPa or less.

Here, the dope flexing will be described.

The metal support in the casting step is preferably mirror finished, and the metal support is preferably a stainless steel belt or a plated drum. The width of the casting can be 1 to 4 m. The surface temperature of the metal support of the flexible process is preferably from -50 DEG C to less than the boiling point of the solvent, while a higher temperature is preferable because it can speed up the drying speed of the web, while too high a value may cause the web to foam or deteriorate in planarity have. The preferred support temperature is 0 to 40 占 폚, more preferably 5 to 30 占 폚.

Alternatively, it is preferable that the web be gelled by cooling to peel off the drum in a state containing a large amount of residual solvent.

The method of controlling the temperature of the metal support is not particularly limited, but there is a method of spraying hot air or cold air, or a method of bringing hot water into contact with the back surface of a metal support. The use of hot water is preferable because the heat transfer is performed efficiently and the time until the temperature of the metal support becomes constant is short. In the case of using warm air, a wind having a temperature higher than the target temperature may be used.

The amount of the residual solvent when peeling the web from the metal support is preferably from 10 to 150% by mass, more preferably from 20 to 40% by mass or from 60 to 130% by mass, in order for the rolled cellulose ester to exhibit good planarity, Particularly preferably 20 to 30% by mass or 70 to 120% by mass.

In the present invention, the amount of the residual solvent is defined by the following formula.

Amount of residual solvent (mass%) = {(M-N) / N} 100

M is the mass of the sample taken from the web or film at any point during or after the production, and N is the mass after heating the M at 115 占 폚 for 1 hour.

Further, in the step of drying the rolled cellulose ester, it is preferable that the web is peeled from the metal support and further dried to make the residual solvent amount not more than 1% by mass, more preferably not more than 0.1% by mass, particularly preferably 0% To 0.01% by mass or less.

In the film drying process, generally, a roll drying method (a method of drying a plurality of rolls disposed at upper and lower sides by alternately passing webs) or a method of drying while conveying the web by a tenter method is employed.

In order to produce the cellulose ester film of the present invention, the cellulose ester film is stretched in the carrying direction (= long direction) at a large amount of the residual solvent of the web immediately after peeling from the metal support, and further, It is particularly preferable to conduct stretching in the width direction.

After the cellulose ester film of the present invention is prepared and saponified, the polarizer of the present invention can be produced by bonding to the polarizer described below.

(Polarizer)

The polarizing plate used in the present invention and the liquid crystal display device of the present invention will be described.

<Polarizer>

The polarizer, which is a principal component of the polarizer, is a device that allows only light of a polarization plane in a certain direction to pass therethrough. A typical polarizer film currently known is a polyvinyl alcohol polarizer film, which is obtained by dyeing a polyvinyl alcohol film with iodine, Some dyes are colored.

In the present invention, it is particularly preferable to use a polarizer having an ethylene-modified polyvinyl alcohol and a thickness of 5 to 20 탆.

The polarizer is formed from an ethylene-denatured polyvinyl alcohol having an ethylene unit content of 1 to 4 mol%, a degree of polymerization of 2000 to 4000 and a saponification degree of 99.0 to 99.99 mol%, an ethylene denatured polyvinyl alcohol having a hydrothermal decomposition temperature of 66 to 73 DEG C It is preferable to be produced from an alcohol film.

In order to produce a polarizer from the ethylene-modified PVA film, for example, the ethylene-modified PVA film may be dyed, uniaxially stretched, fixed and dried, and further heat- There is no particular limitation on the order of operations of the fixed processing. In addition, uniaxial stretching may be performed twice or more.

The uniaxial stretching can be performed by wet stretching or dry heat stretching. The film can be stretched by heating in hot water such as an aqueous boric acid solution (which may be in a solution containing the dye or in a fixing treatment bath described later) or an ethylene- . Although the stretching temperature is not particularly limited, it is preferably 30 to 90 占 폚 in the case of stretching (wet stretching) the ethylene-modified PVA film in hot water, and 50 to 180 占 폚 in case of dry stretching.

The stretching magnification (uniaxial stretching ratio in the case of uniaxial stretching) of uniaxial stretching is preferably 4 times or more, and most preferably 5 times or more, in terms of the polarization performance of the polarizing film. The upper limit of the draw ratio is not particularly limited, but if it is 8 times or less, it is preferable that uniform draw is likely to be obtained.

The thickness of the polarizer after stretching is preferably 2 to 25 占 퐉, more preferably 5 to 20 占 퐉, and particularly preferably 5 to 15 占 퐉.

&Lt; Polarizing plate production method >

The polarizer thus obtained is conventionally used as a polarizing plate by bonding the polarizing plate protective film of the present invention to both sides thereof. As the adhesive for bonding, PVA adhesive, urethane adhesive and the like can be mentioned. Among them, PVA adhesive is preferably used. The polarizing plate protective film is saponified by an alkali solution before being bonded to the polarizer.

(Pressure-sensitive adhesive layer)

The polarizer used in the present invention is adhered to a liquid crystal glass cell through an adhesive layer. In the present invention, it is preferable to produce a pressure-sensitive adhesive layer on a polarizing plate. In preparing the pressure-sensitive adhesive layer, it is preferable that the surface of the polarizing plate is first surface-modified by saponification treatment, corona discharge, plasma irradiation under atmospheric pressure, or the like.

Subsequently, a pressure-sensitive adhesive layer is formed on the surface of the surface-modified polarizing plate by a pressure-sensitive adhesive. As the pressure-sensitive adhesive, various pressure-sensitive adhesives such as a rubber pressure-sensitive adhesive, an acrylic pressure-sensitive adhesive, and a silicone pressure-sensitive adhesive can be used, but an acrylic pressure-sensitive adhesive which is colorless and transparent and has good adhesiveness to a liquid crystal cell is generally used. As the acrylic pressure-sensitive adhesive, it is preferable that the weight average molecular weight of the base polymer is about 300,000 to 2.5 million.

Examples of the monomer used in the acrylic polymer which is the base polymer of the acrylic pressure-sensitive adhesive include alkyl (meth) acrylates {alkyl (meth) acrylate is alkyl acrylate and / or alkyl methacrylate, Can be used. Specific examples of such alkyl (meth) acrylates include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate and 2-ethylhexyl (meth) Can be used. (Meth) acrylic acid, glycidyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, and N-methylol (meth) acrylate may be used in place of a part of the alkyl (meth) acrylate in order to impart polarity to the resulting acrylic polymer. ) Acrylamide can also be used in combination. If desired, other copolymerizable monomers such as vinyl acetate and styrene can be used in combination to the extent that the adhesive property of the acrylic polymer is not impaired.

The acrylic polymer can be prepared by various known methods, and for example, a radical polymerization method such as a bulk polymerization method, a solution polymerization method and a suspension polymerization method can be appropriately selected. As the radical polymerization initiator, various known azo compounds and peroxide compounds can be used. Of these production methods, solution polymerization is preferred, and polar solvents such as ethyl acetate and toluene are generally used as solvents for the acrylic polymer.

As the base polymer of the rubber-based pressure-sensitive adhesive, for example, natural rubber, isoprene rubber, styrene-butadiene rubber, regenerated rubber, polyisobutylene rubber, further styrene-isoprene-styrene rubber, styrene- . Examples of the base polymer of the silicone-based pressure-sensitive adhesive include dimethylpolysiloxane and diphenylpolysiloxane.

The pressure-sensitive adhesive preferably contains a crosslinking agent. Examples of the crosslinking agent include a polyisocyanate compound, a polyamine compound, a melamine resin, a urea resin, an epoxy resin, and a metal chelate. If necessary, a tackifier, a plasticizer, a filler, an antioxidant, an ultraviolet absorber, a silane coupling agent, and the like may be suitably used in the pressure-sensitive adhesive within a range not deviating from the object of the present invention.

Formation of the pressure-sensitive adhesive layer is not particularly limited, and a method of applying a pressure-sensitive adhesive (solution) to the surface of the modified polarizing plate and drying, and a method of transferring the pressure-sensitive adhesive layer onto the surface of the polarizing plate modified with a release sheet.

The thickness of the pressure-sensitive adhesive layer (dry film thickness) is preferably thin in consideration of retardation of the pressure-sensitive adhesive layer itself and dimensional stability, but specifically, it is preferably about 5 to 30 占 퐉.

Examples of the constituent material of the release sheet include synthetic resin films such as paper, polyethylene, polypropylene, and polyethylene terephthalate. The surface of the release sheet may be subjected to a peeling treatment such as a silicone treatment, a long-chain alkyl treatment, or a fluorine treatment, if necessary, in order to improve the peelability from the pressure-sensitive adhesive layer.

&Lt; Bonding of Polarizer to Liquid Crystal Glass Cell >

Normally, an automatic bonding apparatus is used for bonding to a liquid crystal glass cell, but in this apparatus, the polarizing plate is adhered to the glass cell by using a roller while adhering it to the apparatus in order to secure planarity. At this time, when the pressure-sensitive adhesive is strong, the polarizing plate is also subjected to a force, which causes retardation fluctuation of the polarizing plate protective film which causes a color shift with time.

In the present invention, the color shift can be suppressed regardless of the strength of the pressure-sensitive adhesive and the thickness of the pressure-sensitive adhesive layer.

(Relationship with IPS type liquid crystal glass cell)

The liquid crystal layer of the liquid crystal panel in the IPS type liquid crystal display device has a homogeneous alignment in parallel with the substrate surface in the initial state and in a plane parallel to the substrate, the director of the liquid crystal layer is parallel or slightly parallel to the electrode wiring direction The direction of the director of the liquid crystal layer shifts in a direction perpendicular to the direction of the electrode wiring in accordance with the application of the voltage and the director direction of the liquid crystal layer is shifted by 45 deg. When inclined in the direction of the electrode wiring, the liquid crystal layer at the time of applying the voltage turns the azimuth angle of polarization of the polarizing light by 90 degrees like a half wave plate, and the azimuth angle of the polarized light and the transmission axis of the exit- .

The IPS type liquid crystal display device of the present invention is preferably used for a large-sized liquid crystal television. The screen size can be preferably 17 or more, more preferably 26 to 100 or so.

The IPS type liquid crystal display device also includes an FFS (fringe field switching) mode and an FLC (ferroelectric liquid crystal) mode in addition to the so-called IPS mode.

Hereinafter, the present invention will be described in detail by way of examples, but the present invention is not limited thereto.

&Lt; Prescription 1: Preparation of Samples 1 to 6 >

(Prescription of Dope Composition A)

Triacetyl cellulose (acetyl substitution degree: 2.9) 85 parts by mass

· 1.5 parts by mass of 2- (2'-hydroxy-3 ', 5'-di-t-butylphenyl) benzotriazole

Methyl methacrylate-2-hydroxyethyl acrylate copolymer 8 parts by mass

  (80/20 (mass ratio)) Mw; 8000

Methyl acrylate polymer (*) Mw; 1000 5 parts by mass

475 parts by mass of methylene chloride

Ethanol 50 parts by mass (*)

A polymer of Mw 1000 and Mn 700 was obtained by polymerizing a methyl acrylate monomer by the polymerization method described in Example 3 of Japanese Patent Laid-Open No. 2000-128911. The hydroxyl value (OHV; mg / g KOH) of this reaction was 50.

(Matte Solution Composition)

11.0 parts by mass of a silica particle dispersion having an average particle diameter of 16 nm

Methylene chloride (first solvent) 76.1 parts by mass

Ethanol (second solvent) 3.5 parts by mass

Acetylpropionyl cellulose (acetyl substitution degree: 2.06, propionyl substitution degree: 0.79) 1.9 parts by mass

(Preparation of mat agent solution)

20 parts by mass of silica particles having an average particle diameter of 16 nm (AEROSIL R972, manufactured by Nippon Aerosil Co., Ltd.) and 80 parts by mass of methanol were thoroughly stirred and mixed for 30 minutes to obtain a silica particle dispersion. This dispersion was put into a dispersing machine together with the following composition and further stirred for 30 minutes or more to dissolve each component to prepare a matting agent solution.

The prescribed dope composition A was placed in a sealed container, heated to 70 DEG C, and completely dissolved in cellulose triacetate (TAC) while stirring to obtain a dope. The time required for dissolution was 4 hours. After the dope composition A was filtered, 6.5 parts by mass of the matte solution was mixed, and the mixture was uniformly plied on a stainless steel band support at 22 ° C at a dope temperature of 35 ° C by using a belt softener. The temperature of the stainless steel band support was 20 占 폚.

Thereafter, after drying to a releasable range, the dope was peeled off from the stainless steel band support. The residual solvent amount of the dope at this time was 25 mass%. The time required from dope flexing to peeling was 3 minutes. The film was peeled off from the stainless steel band support with a tensile force of 10 kg / m, stretched by 2% in the transverse direction with a tenter under 140 캜, and dried in a drying zone of 120 캜 and 135 캜 while being conveyed by a plurality of rolls. A width of 10 mm and a height of 5 占 퐉 to prepare a cellulose triacetate film sample 1 having a thickness of 40 占 퐉.

The film width was 1500 mm and the winding length was 1000 m. (Measured by a haze meter HM150 manufactured by Murakami Color Research Laboratory Co., Ltd.) was 3%, and a single transmittance (as measured by a spectrophotometer U-4100 equipped with an integrating sphere manufactured by HITACHI SEISAKUSHO Co., Ltd.) %. The initial tension was 10 kg / m and the final tension was 8 kg / m.

Samples 2, 3, 4, 5 and 6 having thicknesses of 20 탆, 30 탆, 50 탆, 60 탆 and 80 탆 were prepared in the same manner. In addition, samples 2 and 3 had a winding length of 1000 m.

&Lt; Prescription 2: Preparation of sample 7 >

(Composition of additive solution)

P-toluenesulfonanilide 44.3 parts by mass

7.9 parts by mass of 2-hydroxy-4-octanoxybenzophenone

Methylene chloride (first solvent) 58.8 parts by mass

Methanol (second solvent) 8.4 parts by mass

Triacetyl cellulose (acetyl substitution degree: 2.9) 2.2 parts by mass

95.6 parts by mass of the dope composition A, 1.8 parts by mass of the mat agent solution and 6.7 parts by mass of the additive solution were mixed after filtration, respectively, and Sample 7 was prepared in the same manner as Sample 1.

&Lt; Prescription 3: Preparation of sample 8 >

A sample 8 was prepared in the same manner as in the sample 1 except that 13 parts by mass of octaacetyl sucrose was used instead of the methyl methacrylate-2-hydroxyethyl acrylate copolymer and the methyl acrylate polymer of the dope composition A described above.

<Saponification Condition>

Samples 1 to 8 were immersed for 2 minutes in an alkali solution bath in which an aqueous solution of sodium hydroxide of 1.5 was adjusted to 55 캜. The convection rate of the alkali solution was 50 m / min. A partition plate was provided near the outlet of the alkali solution tank, and the portion was adjusted to 58 ° C.

Subsequently, the film subjected to the alkali immersion treatment was washed with water, then immersed in a 0.05 mol / L sulfuric acid aqueous solution for 30 seconds, and further washed with water. Then, dewatering with an air knife was repeated three times and dried in a drying chamber at 70 DEG C for 30 seconds to prepare a saponification-treated polarizing plate protective film.

&Lt; Production of Polarizer A &

100 parts by mass of an ethylene-modified PVA having an ethylene unit content of 2.1 mol%, a degree of saponification of 99.92 mol% and a degree of polymerization of 3000 was melt-kneaded with 10 parts by mass of glycerin and 200 parts by mass of water, and after defoaming, Followed by melt extrusion. The ethylene-modified PVA film obtained after drying and heat treatment had a thickness of 40 占 퐉 and an average value of hot water cutting temperature of the film was 70 占 폚.

Subsequently, the ethylene-modified PVA film was immersed in water at 30 DEG C for 60 seconds to preliminarily swell, and the film was preliminarily swollen in an aqueous solution having a boric acid concentration of 40 g / liter, an iodine concentration of 0.4 g / liter and a potassium iodide concentration of 60 g / Lt; / RTI &gt; Subsequently, uniaxial stretching was carried out in an aqueous solution having a boric acid concentration of 4% at a temperature of 55 ° C in six times, and the resultant was immersed in an aqueous solution of potassium iodide concentration of 60 g / liter, boric acid concentration of 40 g / liter, zinc chloride concentration of 10 g / Immersed and fixed. Thereafter, the ethylene-modified PVA film was taken out and hot-air dried at 40 캜 under a constant length, and further heat treatment was performed at 100 캜 for 5 minutes. The obtained polarizer had an average thickness of 10 탆, a transmittance of 43.0%, a polarization degree of 99.5% and a dichroic ratio of 40.1 for the polarization performance.

&Lt; Production of Polarizer B &

A polyvinyl alcohol film (manufactured by Kuraray Co., Ltd., average polymerization degree: 2400, saponification degree: 99.9 mol%, length: 800 m) having a thickness of 80 탆 and a width of 3100 mm was immersed in pure water at 30 캜 for 60 seconds, Direction (flow direction) to a draw ratio of 2.5 times. Subsequently, the resultant was immersed in an aqueous solution of 0.05% of iodine / potassium iodide (mass ratio = 1/10) at 30 ° C for 60 seconds and at the same time, stretched so as to have a total draw ratio of 2.8, and then a boric acid concentration of 3% by mass at 40 ° C, And then stretched until the total draw ratio became three times in an aqueous solution having a potassium concentration of 2 mass%.

And further stretched to a total draw ratio of 6 in an aqueous solution having a boric acid concentration of 4% by mass at 60 캜 and a potassium iodide concentration of 3% by mass. Thereafter, it was immersed in an aqueous solution of 5% by mass of potassium iodide concentration at 25 캜 for 30 seconds without smoothing. Subsequently, drying was carried out at 40 ° C for 1 minute while maintaining the tension, to obtain a polarizer having a thickness of 20 μm and a width of 1550 mm. Polarizers were produced continuously.

&Lt; Production of polarizing plate &

While the polarizers A and B and the sample film were running in the longitudinal direction, they were bonded to the side of the liquid crystal glass cell of the polarizer with a polyvinyl alcohol adhesive, and on the opposite side of the cell side, Konica Minolta Tact KC4UY (hereinafter abbreviated as 4UY) (Hereinafter abbreviated as 8 UY) Fujitak UZ-TAC 40 um (hereinafter abbreviated as 4 UZ) and 80 um (hereinafter abbreviated as 8 UZ) manufactured by Fuji Shashin Film Co., . In addition, a polarizing plate was produced in a sheet form in which the size was insufficient.

&Lt; Production of sticking type polarizing plate >

A solution of an acrylic pressure-sensitive adhesive (copolymer of butyl acrylate / methacrylic acid / hydroxyethyl acrylate, molecular weight: 2,000,000, containing 0.3% of isocyanate crosslinking agent) was applied onto the surface of the polarizing plate on the side of the liquid crystal glass cell, Lt; RTI ID = 0.0 &gt; g / m. &Lt; / RTI &gt;

<Measurement method of film thickness and thickness>

When the thickness is less than 10 mu m, the thin film spectrophotometer was measured by using "MCPD-2000", "instant multi-photometric system" manufactured by Otsuka Denshi Co., When the thickness is 10 탆 or more, it was measured using a digital micrometer "KC-351C type" manufactured by Anritsu.

&Lt; Method of Measuring Color Shift of Liquid Crystal Display &

A liquid crystal panel was taken out from a liquid crystal display device (Panasonic liquid crystal television VIERA TH-26LX60, manufactured by Matsushita Electric Industries, Ltd.) containing liquid crystal cells of the IPS mode to remove the polarizing plate disposed above and below the liquid crystal cell, Glass surfaces (front and back) were cleaned. Subsequently, the polarizing plate having the pressure-sensitive adhesive layer of the present invention was adhered to the electrode side of the liquid crystal glass cell using a polarizing plate adhering device so that the slow axis of the polarizer was parallel to the long side of the liquid crystal cell (0 ± 0.2 degrees).

Subsequently, a black image was displayed on the liquid crystal display device, and the hue, x value and y value in the 360 DEG direction in the polar angle direction of 60 DEG were measured using the product name "EZ Contrast 160D "

The difference between the maximum value and the minimum value of the x and y values of the omnidirectional x and y values calculated by EZ Contrast at a polar angle of 60 degrees azimuth angle of 45 degrees is expressed by the formula: ) ² + (y (max) -y (min)) ² } ^1/2 .

The azimuth angle of 45 占 indicates the azimuth rotated by 45 占 in the counterclockwise direction when the long side of the panel is set to 0 占. The polar angle of 60 deg. Indicates the azimuth at 60 deg. When the vertical direction to the panel is 0 deg.

This measurement was carried out after adhesion of the polarizing plate to the liquid crystal glass cell, 2 hours at 23 캜 and 55% RH, and 2000 hours at 35 캜 and 80% RH.

As is apparent from Table 1, the IPS type liquid crystal display device of the present invention exhibits an effect of improving the color shift by adjusting the rigidity.

Claims (6)

1. An IPS type liquid crystal display device having an IPS type liquid crystal glass cell and two polarizing plates bonded to both sides of the liquid crystal glass cell for IPS via an adhesive layer, Wherein at least one of the two polarizing plates comprises a polarizer and two polarizing plate protective films joined to both sides of the polarizing element, The total thickness of the polarizing plate is 80 to 150 mu m, A stiffness (ST) of 20 to 80 (g) at 23 占 폚 and 55% RH, Wherein Ro of the polarizing plate protective film on the side of the polarizing plate protective film of the polarizing plate sandwiching the liquid crystal glass cell for IPS and the polarizer among the two polarizing plate protective films of the polarizing plate is 0? Ro? 5 nm, wherein Rt defined by ii is -5? Rt? 5 nm and the film thickness is 20 to 60 占 퐉. &Lt; EMI ID = Ro = (nx-ny) xd &Lt; EMI ID = Rt = {(nx + ny) / 2-nz} xd (Where nx represents the refractive index in the in-plane slow axis direction, ny represents the refractive index in the direction perpendicular to the slow axis, nz represents the refractive index in the film thickness direction, and d represents the film thickness (nm) The IPS liquid crystal display device according to claim 1, wherein the total thickness of the at least one polarizing plate is 80 to 140 탆. The IPS liquid crystal display device according to claim 1 or 2, wherein at least one of the two polarizing plate protective films is made of cellulose ester. 4. The IPS liquid crystal display device according to claim 3, wherein the polarizing plate protective film comprising the cellulose ester is a cellulose ester film containing a compound having negative directional birefringence. A method of manufacturing an IPS liquid crystal display device having a step of adhering two polarizing plates to both sides of an IPS type liquid crystal glass cell via an adhesive layer, Wherein at least one of the two polarizing plates comprises a polarizer and two polarizing plate protective films joined to both sides of the polarizing element, The total thickness of the polarizing plate is 80 to 150 mu m, A stiffness (ST) of 20 to 80 (g) at 23 占 폚 and 55% RH, Wherein Ro of the polarizing plate protective film on the side of the polarizing plate protective film of the polarizing plate sandwiching the liquid crystal glass cell for IPS and the polarizer among the two polarizing plate protective films of the polarizing plate is 0? Ro? 5 nm, wherein Rt defined by ii is -5? Rt? 5 nm and the film thickness is 20 to 60 占 퐉. &Lt; EMI ID = Ro = (nx-ny) xd &Lt; EMI ID = Rt = {(nx + ny) / 2-nz} xd (Where nx represents the refractive index in the in-plane slow axis direction, ny represents the refractive index in the direction perpendicular to the slow axis, nz represents the refractive index in the film thickness direction, and d represents the film thickness (nm) The method for manufacturing an IPS liquid crystal display device according to claim 5, wherein the total film thickness of the at least one polarizing plate is 80 to 140 탆.

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