JP2013045041A - Roll circular polarizer for traverse field switching mode type liquid crystal display device, and traverse field switching mode type 3d liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a roll circular polarizer for traverse field switching mode type liquid crystal display device providing a high contrast image with little irregularity, and having high wet heat durability and high productivity, and a traverse field switching mode type 3D liquid crystal display device using the roll circular polarizer.SOLUTION: The roll circular polarizer for traverse field switching mode type liquid crystal display devices is formed by superposing a first protective film, a polarizer, and a second protective film in this order. The polarizer includes an absorption axis that is oblique to the longitudinal direction of the roll circular polarizer for the traverse field switching mode type liquid crystal display devices. An in-plane-directional retardation value Ro of the first protective film satisfies the following general expression (i), and an angle formed between a slow axis of the first protective film and the absorption axis of the polarizer is 45°±10°. (i) The general expression: 80≤Ro≤200.

Description

  The present invention relates to a roll-shaped circularly polarizing plate for a transverse electric field type switching mode liquid crystal display device using a polarizer having an absorption axis oblique to the longitudinal direction and the width direction, and 3D using the roll-shaped circularly polarizing plate. The present invention relates to a liquid crystal display device.

  In recent years, the liquid crystal display market has been growing rapidly.

  Among various liquid crystal display systems, the horizontal electric field type switching mode type (hereinafter also referred to as in-plane switching (IPS) system) has a fast response speed, a wide viewing angle, and a high contrast in an oblique direction. It is preferably used (see, for example, Patent Documents 1 and 2). Also in the 3D (stereoscopic) display field, the IPS system is preferably used for other systems because of the above-mentioned merit.

  It is known that an active 3D display has an optical element (λ / 4 polarizing plate) in which a polarizer and a λ / 4 retardation plate are combined, so that the 3D viewing area can be expanded. For example, Patent Document 3 discloses a stereoscopic image display device using glasses that use only one polarizing plate in order to suppress flicker of external light and improve the brightness of glasses. In this document, it is possible to suppress crosstalk when the head is tilted by setting the configuration of the circularly polarizing plate and the glasses to the front of the display as (λ / 4 plate) / (liquid crystal cell) / (linear polarizing plate). Disclosure.

  In addition to displays with linearly polarized light, such as liquid crystal displays (LCDs) and organic EL displays that use circularly polarizing plates to prevent reflection, displays that emit non-linearly polarized light, such as plasma displays. An organic EL display that does not use a circularly polarizing plate for preventing reflection can also be used.

  The production method of the λ / 4 polarizing plate is a method in which a retardation film is stretched in an oblique direction and bonded to a polarizer stretched in a longitudinal direction or a transverse direction, or a longitudinal stretched in a longitudinal direction or a transverse direction. A method of laminating a retardation film in a sheet mode with a polarizer is common. Further, for example, as shown in Patent Document 4, a method of obtaining a polarizer having an absorption axis obliquely in the alignment direction of the support film by applying a liquid crystal compound on the support film subjected to the alignment treatment is known. It has been.

  The polarizer has a strong contraction force in the stretching direction of the polarizer and in the direction perpendicular to the stretching depending on the heat when the panel is turned on and the humidity of the usage environment. The shrinkage force to the polarizer increases from the center of the panel bonded to the polarizing plate according to the outside, but when the polarizing plate absorption axis is arranged horizontally or vertically with respect to the liquid crystal panel, it is strongest at the four corners of the liquid crystal screen. Contraction force works.

  Therefore, polarization unevenness occurs at the four corners of the liquid crystal screen due to deformation (extension / contraction) of the polarizing plate. In particular, in the case of 3D panels, the circularly polarized light that should be obtained is elliptically polarized light, and the contrast is lowered and the 3D stereoscopic effect is remarkably impaired. It has become a big problem, and further improvement in contrast and improvement in image unevenness in the IPS system have been problems.

JP 2008-12-02479 A International Publication No. 2008/044463 JP 2002-82307 A JP 2011-22223 A

  The present invention has been made in order to solve such problems, and the problem to be solved is a lateral electric field switching mode liquid crystal display device having high contrast, less image unevenness, excellent wet heat durability and high productivity. An object of the present invention is to provide a roll-shaped circularly polarizing plate for use, and a lateral electric field type switching mode type 3D liquid crystal display device using the roll-shaped circularly polarizing plate.

  The above object of the present invention is achieved by the following configurations.

  1. A roll-shaped circularly polarizing plate for a transverse electric field type switching mode liquid crystal display device, in which a first protective film, a polarizer, and a second protective film are laminated in this order, wherein the polarizer is the transverse electric field type switching mode type It has an absorption axis that is oblique with respect to the longitudinal direction of the roll-shaped circularly polarizing plate for a liquid crystal display device, and the retardation value Ro in the in-plane direction of the first protective film is a temperature of 23 ° C. and a relative humidity of 55% RH. In the measurement at an optical wavelength of 590 nm under the environment, the angle that the slow axis of the first protective film satisfies the following general formula (i) and the absorption axis of the polarizer is 45 ° ± 10 °. A roll-shaped circularly polarizing plate for a horizontal electric field type switching mode type liquid crystal display device characterized by the above.

General formula (i) 80 ≦ Ro ≦ 200
(Wherein, a _{Ro = (n x -n y)} × d, n x is a refractive index in a slow axis direction in a plane of the film, n _y is a refractive in a direction perpendicular to the slow axis in the film plane (Where d represents the thickness of the film (nm))
2. The polarizer has an alignment film in which a lyotropic liquid crystal compound is aligned, the alignment film is aligned on a plastic substrate, and the absorption axis is inclined 45 ° ± 10 ° with respect to the longitudinal direction. 2. A roll-shaped circularly polarizing plate for a transverse electric field type switching mode liquid crystal display device according to 1 above.

  3. 2. The lateral electric field type switching mode liquid crystal display according to 1 above, wherein the polarizer is obtained by performing an alignment treatment on the second protective film and having an absorption axis oblique to the longitudinal direction. Rolled circularly polarizing plate for equipment.

  4). A lateral electric field type switching mode type 3D liquid crystal display device comprising a liquid crystal cell and two polarizing plates sandwiching the liquid crystal cell, wherein the lateral electric field type according to any one of 1 to 3 is provided on a viewing side of the liquid crystal cell. A lateral electric field type switching mode type 3D liquid crystal display device, characterized in that a roll-shaped circularly polarizing plate for a switching mode type liquid crystal display device is arranged so that the second protective film is on the electrode side.

  According to the present invention, a roll circular polarizing plate for a horizontal electric field type switching mode liquid crystal display device having high contrast, little image unevenness, excellent wet heat durability, and high productivity, and a horizontal direction using the roll circular polarizing plate An electric field type switching mode type 3D liquid crystal display device can be provided.

It is a schematic diagram of an example of a roll-shaped polarizing plate in which the polarizer has an absorption axis oblique to the longitudinal direction of the polarizing plate. It is an example of a conceptual diagram of 3D liquid crystal glasses. 1 is a schematic view of a liquid crystal display device according to a preferred embodiment of the present invention.

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

  As a result of intensive studies, the roll-shaped circularly polarizing plate is formed by laminating a roll-shaped circularly polarizing plate first protective film, a polarizer, and a second protective film for a transverse electric field type switching mode liquid crystal display device in this order. The polarizer has an oblique absorption axis with respect to the longitudinal direction of the roll-shaped polarizing plate, the in-plane retardation value Ro of the first protective film satisfies the general formula (i) described below, and The roll-shaped circularly polarizing plate whose angle between the slow axis of the first protective film and the absorption axis of the polarizer is 45 ° ± 10 ° has a high three-dimensional effect, little image unevenness, high contrast, and durability against wet heat It has been found that an IPS 3D display having excellent performance can be provided at low cost.

  The roll-shaped circularly polarizing plate of the present invention is provided on the viewing side of the display for display. The 3D glasses for viewing the display display have a λ / 4 phase difference plate. By combining the 3D glasses and the display for display, a good stereoscopic image with high contrast and little unevenness can be viewed. can do.

<Roll circular polarizing plate>
The roll-shaped circularly polarizing plate of the present invention is a roll-shaped polarizing plate in which a first protective film, a polarizer, and a second protective film are laminated in this order, and the polarizer is oblique to the longitudinal direction of the polarizing plate. It has an absorption axis. This polarizing plate is laminated | stacked on the liquid crystal cell in order of the 2nd protective film, the polarizer, and the 1st protective film. The absorption axis of a polarizer having an oblique absorption axis according to the present invention located on the upper side of the IPS liquid crystal cell is orthogonal to 90 degrees with respect to the absorption axis of the lower polarizing plate located on the lower side of the liquid crystal cell.

  Moreover, the polarizer having an oblique absorption axis according to the present invention may be integrated with the second protective film.

  Hereinafter, the first protective film, the polarizer, and the second protective film will be described.

<Second protective film>
The second protective film is disposed between the liquid crystal cell on the electrode side and the polarizer. In the second protective film, the in-plane direction retardation Ro is preferably 0 nm ≦ Ro ≦ 5 nm, and the thickness direction retardation Rt is preferably −5 nm ≦ Rt ≦ 5 nm. The means for setting Ro and Rt to the desired values is not limited as long as the film is a single sheet, but is preferably a cellulose ester containing a compound having negative orientation birefringence and having a film thickness of 20 ˜60 μm.

  The second protective film is preferably a uniform film. For example, even if a plurality of films are overlapped or a coating layer is provided to have the same Ro and Rt, the second protective film is a single film. In the case, the performance improvement effect is greater.

<Cellulose ester>
The second protective film according to the present invention is not limited as long as the phase difference Ro in the in-plane direction and the phase difference Rt in the thickness direction are within the above ranges, but may be a protective film made of a cellulose ester film. preferable. Cellulose esters include cellulose such as triacetyl cellulose (TAC), diacetyl cellulose (DAC), cellulose acetate propionate (CAP), cellulose acetate butyrate (CAB), cellulose acetate phthalate, cellulose acetate trimellitate, and cellulose nitrate. Examples include esters.

  The cellulose used as a raw material for the cellulose ester used in the present invention is not particularly limited, and examples thereof include cotton linter, wood pulp, and kenaf. Moreover, although the cellulose ester obtained from these can be used individually or in mixture of arbitrary ratios, it is preferable to use 50 mass% or more of cotton linters.

  When the molecular weight of the cellulose ester film is large, the elastic modulus is increased. However, when the molecular weight is excessively increased, the viscosity of the cellulose ester solution becomes too high, and the productivity is lowered. The molecular weight of the cellulose ester is preferably 30000-200000 in terms of number average molecular weight (Mn), more preferably 500000-200000.

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

  The measurement conditions are as follows.

Solvent: Methylene chloride Column: Shodex K806, K805, K803G (Used by connecting three Showa Denko Co., Ltd.)
Column temperature: 25 ° C
Sample concentration: 0.1% by mass
Detector: RI Model 504 (manufactured by GL Sciences)
Pump: L6000 (manufactured by Hitachi, Ltd.)
Flow rate: 1.0ml / min
Calibration curve: Standard polystyrene STK standard polystyrene (manufactured by Tosoh Corporation) Mw = 1,000,000-500 calibration curves with 13 samples were used. The 13 samples are preferably used at approximately equal intervals.

(Compound having negative orientation birefringence)
The compound having negative orientation birefringence that can be used in the present invention means a material exhibiting negative birefringence in the stretching direction of the film in the cellulose ester film, and includes acrylic polymer, polyester, Examples thereof include a compound having a furanose structure or a pyranose structure, a sulfone compound, and the like.

  Whether or not it has negative orientation birefringence can be determined by measuring the birefringence of the film between the system with the compound added and the system without the compound with a birefringence meter and comparing the difference. be able to.

<Acrylic polymer, polyester, compound having furanose structure or pyranose structure>
Next, acrylic polymers, polyesters, and compounds having a furanose structure or a pyranose structure that can be used in the present invention will be described.

<Acrylic polymer>
The cellulose ester film that can be used in the present invention preferably contains an acrylic polymer having a weight-average molecular weight of 500 or more and 30000 or less that exhibits negative orientation birefringence in the stretching direction, and the acrylic polymer is an aromatic ring. Is preferably an acrylic polymer having a side chain or an acryl group having a cyclohexyl group in the side chain.

  By controlling the composition of the polymer so that the weight average molecular weight of the polymer is 500 or more and 30000 or less, the compatibility between the cellulose ester and the polymer can be improved.

  In particular, for an acrylic polymer, an acrylic polymer having an aromatic ring in the side chain, or an acrylic polymer having a cyclohexyl group in the side chain, if the weight average molecular weight is preferably 500 or more and 10,000 or less, in addition to the above, The cellulose ester film has excellent transparency and extremely low moisture permeability, and exhibits excellent performance as a protective film for polarizing plates.

  Since the polymer has a weight average molecular weight of 500 or more and 30000 or less, it is considered to be between the oligomer and the low molecular weight polymer. In order to synthesize such a polymer, it is difficult to control the molecular weight in normal polymerization, and it is desirable to use a method that can align the molecular weight as much as possible without increasing the molecular weight.

  Such polymerization methods include a method using a peroxide polymerization initiator such as cumene peroxide and t-butyl hydroperoxide, a method using a polymerization initiator in a larger amount than normal polymerization, and a mercapto compound in addition to the polymerization initiator. And a method using a chain transfer agent such as carbon tetrachloride, a method using a polymerization terminator such as benzoquinone and dinitrobenzene in addition to the polymerization initiator, and further, JP 2000-128911 A or JP 2000-344823 A Or a bulk polymerization method using a compound having a single thiol group and a secondary hydroxy group, or a polymerization catalyst in which the compound and an organometallic compound are used in combination. In particular, the method described in the publication is preferred.

  Although the monomer as a monomer unit which comprises the polymer useful for this invention is mentioned below, it is not limited to this.

  The ethylenically unsaturated monomer unit constituting the polymer obtained by polymerizing the ethylenically unsaturated monomer is as a vinyl ester, for example, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl valerate, vinyl pivalate, caproic acid. Vinyl, vinyl caprate, vinyl laurate, vinyl myristate, vinyl palmitate, vinyl stearate, vinyl cyclohexanecarboxylate, vinyl octylate, vinyl methacrylate, vinyl crotonate, vinyl sorbate, vinyl benzoate, vinyl cinnamate Etc .; As acrylate ester, for example, 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 (n-, i-), octyl acrylate (n-, i-), nonyl acrylate (n-, i-), myristyl acrylate (n-, i-), acrylic Cyclohexyl acid, acrylic acid (2-ethylhexyl), benzyl acrylate, phenethyl acrylate, acrylic acid (ε-caprolactone), acrylic acid (2-hydroxyethyl), acrylic acid (2-hydroxypropyl), acrylic acid (3- Hydroxypropyl), acrylic acid (4-hydroxybutyl), acrylic acid (2-hydroxybutyl), acrylic acid-p-hydroxymethylphenyl, acrylic acid-p- (2-hydroxyethyl) phenyl, etc .; The above acrylic acid ester is changed to methacrylic acid ester; Examples thereof include acrylic acid, methacrylic acid, maleic anhydride, crotonic acid, itaconic acid and the like.

  The polymer composed of the above monomers may be a copolymer or a homopolymer, and is preferably a vinyl ester homopolymer, a vinyl ester copolymer, or a copolymer of vinyl ester and acrylic acid or methacrylic acid ester.

  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 a cyclohexyl group. An acrylic polymer having an aromatic ring in the side chain is an acrylic polymer that always contains 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 acrylate monomer having no aromatic ring and cyclohexyl group include, for example, 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 (n-, i-), octyl acrylate (n-, i-) , Nonyl acrylate (n-, i-), myristyl acrylate (n-, i-), acrylic acid (2-ethylhexyl), acrylic acid (ε-caprolactone), acrylic acid (2-hydroxyethyl), acrylic acid (2-hydroxypropyl), acrylic acid (3-hydroxypropyl), acrylic acid (4-hydroxybutyl), acrylic acid (2-hydroxybutyl), acrylic acid 2-methoxy-ethyl), acrylic acid (2-ethoxyethyl), or the acrylic acid ester may include those obtained by changing the methacrylic acid ester.

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

  Examples of acrylic acid or methacrylic acid ester monomers having an aromatic ring include phenyl acrylate, phenyl methacrylate, acrylic acid (2 or 4-chlorophenyl), methacrylic acid (2 or 4-chlorophenyl), and acrylic acid (2 or 3 Or 4-ethoxycarbonylphenyl), methacrylic acid (2 or 3 or 4-ethoxycarbonylphenyl), acrylic acid (o or m or p-tolyl), methacrylic acid (o or m or p-tolyl), benzyl acrylate, Benzyl methacrylate, phenethyl acrylate, phenethyl methacrylate, acrylic acid (2-naphthyl) and the like can be mentioned, but benzyl acrylate, benzyl methacrylate, phenethyl acrylate, and phenethyl methacrylate are preferably used. That.

  Among acrylic polymers having an aromatic ring in the side chain, the acrylic acid or methacrylic acid ester monomer unit having an aromatic ring has 20 to 40% by mass, and the acrylic acid or methacrylic acid methyl ester monomer unit is 50 to 80% by mass. % Is preferable. The polymer preferably has 2 to 20% by mass of an acrylic acid or methacrylic acid ester monomer unit having a hydroxy group.

  Examples of the acrylate monomer having a cyclohexyl group include cyclohexyl acrylate, cyclohexyl methacrylate, acrylic acid (4-methylcyclohexyl), methacrylic acid (4-methylcyclohexyl), acrylic acid (4-ethylcyclohexyl), and methacrylic acid. (4-ethylcyclohexyl) and the like can be mentioned, but cyclohexyl acrylate and cyclohexyl methacrylate can be preferably used.

  In the acrylic polymer having a cyclohexyl group in the side chain, the acrylic acid or methacrylic acid ester monomer unit having a cyclohexyl group has 20 to 40% by mass and preferably 50 to 80% by mass. Moreover, it is preferable to have 2-20 mass% of acrylic acid or methacrylic acid ester monomer units having a hydroxy group in the polymer.

  A polymer obtained by polymerizing the above 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 the cellulose resin.

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

  In the present invention, a polymer having a hydroxy group in the side chain can also be preferably used. The monomer unit having a hydroxy group is the same as the monomer described above, but acrylic acid or methacrylic acid ester is preferable. For example, acrylic acid (2-hydroxyethyl), acrylic acid (2-hydroxypropyl), acrylic acid ( 3-hydroxypropyl), acrylic acid (4-hydroxybutyl), acrylic acid (2-hydroxybutyl), acrylic acid-p-hydroxymethylphenyl, acrylic acid-p- (2-hydroxyethyl) phenyl, or these acrylic acids May be mentioned in which methacrylic acid is substituted, preferably 2-hydroxyethyl acrylate and 2-hydroxyethyl methacrylate. The acrylic acid ester or methacrylic acid ester monomer unit having a hydroxy group in the polymer is preferably contained in the polymer in an amount of 2 to 20% by mass, more preferably 2 to 10% by mass.

  Those containing 2-20% by mass of the above-mentioned monomer unit having a hydroxy group as described above, of course, have excellent compatibility with cellulose ester, retention, dimensional stability, and low moisture permeability. It is particularly excellent in adhesiveness with a polarizer as a polarizing plate protective film, and has an effect of improving the durability of the polarizing plate.

  The method of having a hydroxy group at at least one terminal of the main chain of the acrylic polymer is not particularly limited as long as it has a hydroxy group at the terminal of the main chain, but azobis (2-hydroxyethylbutyrate) ), A method using a radical polymerization initiator having a hydroxy group, a method using a chain transfer agent having a hydroxy group such as 2-mercaptoethanol, a method using a polymerization terminator having a hydroxy group, and a living ion. A method of having a hydroxy group at the terminal by polymerization, a compound having one thiol group and a secondary hydroxy group as disclosed in JP-A No. 2000-128911 or 2000-344823, or the compound and an organic compound Obtained by a method of bulk polymerization using a polymerization catalyst combined with a metal compound Can, preferably the method described in particular publication.

  The polymer produced by the method related to the description in this publication is commercially available as Act Flow Series manufactured by Soken Chemical Co., Ltd., and can be preferably used. The polymer having a hydroxy group at the terminal and / or the polymer having a hydroxy group at a side chain has an effect of significantly improving the compatibility and transparency of the polymer in the present invention.

  Furthermore, a polymer using styrene as an ethylenically unsaturated monomer exhibiting negative orientation birefringence with respect to the stretching direction is preferred in order to develop negative refraction. Examples of styrenes include styrene, methyl styrene, dimethyl styrene, trimethyl styrene, ethyl styrene, isopropyl styrene, chloromethyl styrene, methoxy styrene, acetoxy styrene, chloro styrene, dichloro styrene, bromo styrene, and vinyl benzoic acid methyl ester. Although it is mentioned, it is not a thing limited to these.

  It may be copolymerized with the exemplified monomers listed as the unsaturated ethylenic monomer, or may be used by being dissolved in a cellulose ester using two or more kinds of the above polymers for the purpose of controlling birefringence.

  Furthermore, the cellulose ester film according to the present invention includes an ethylenically unsaturated monomer Xa that does not have an aromatic ring and a hydrophilic group in the molecule, and an ethylenically unsaturated monomer that does not have an aromatic ring in the molecule and has a hydrophilic group. A weight average molecular weight of 500 to 3,000 obtained by polymerizing a polymer X having a weight average molecular weight of 5,000 to 30,000 obtained by copolymerization with Xb, and more preferably an ethylenically unsaturated monomer Ya having no aromatic ring. It is preferable to contain the following polymer Y.

<Polymer X, Polymer Y>
The polymer X that can be preferably used in the present invention is an ethylenically unsaturated monomer Xa that does not have an aromatic ring and a hydrophilic group in the molecule, and an ethylenically unsaturated monomer that does not have an aromatic ring in the molecule and has a hydrophilic group. It is a polymer having a weight average molecular weight of 5,000 to 30,000 obtained by copolymerization with Xb. Preferably, Xa is an acrylic or methacrylic monomer that does not have an aromatic ring and a hydrophilic group in the molecule, and Xb is an acrylic or methacrylic monomer that does not have an aromatic ring in the molecule and has a hydrophilic group.

  The polymer X that can be preferably used in the present invention is represented by the following general formula (1).

General formula (1)
-(Xa) _m- (Xb) _n- (Xc) _p-
More preferably, it is a polymer represented by the following general formula (1-1).

General formula (1-1)
_{- [CH 2 -C (-R 1} ) (- CO 2 R 2)] m - [CH 2 -C (-R 3) (- CO 2 R 4 -OH) -] n - [Xc] p -
(In the formula, R ₁ , R ₃ and R ₅ represent H or CH _3. R ₂ represents an alkyl group having 1 to 12 carbon atoms or a cycloalkyl group. R ₄ and R ₆ represent —CH ₂ —, -C ₂ H ₄ -or -C ₃ H _6- , Xc represents a monomer unit that can be polymerized to Xa and Xb, m, n, and p represent a molar composition ratio, where m ≠ 0, n ≠ 0, m + n + p = 100.)
Although the monomer as a monomer unit which comprises the polymer X of this invention is mentioned below, it is not limited to this.

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

  Examples of the ethylenically unsaturated monomer Xa having no aromatic ring and no hydrophilic group in the molecule include methyl acrylate, ethyl acrylate, propyl acrylate (i-, n-), and butyl acrylate (n-, i- , S-, t-), pentyl acrylate (n-, i-, s-), hexyl acrylate (n-, i-), heptyl acrylate (n-, i-), octyl acrylate (n- I-), nonyl acrylate (n-, i-), myristyl acrylate (n-, i-), acrylic acid (2-ethylhexyl), acrylic acid (ε-caprolactone), acrylic acid (2-ethoxyethyl) ) Or the like, or those obtained by replacing the acrylic ester with a methacrylic ester. Among these, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, and propyl methacrylate (i-, n-) are preferable.

  The ethylenically unsaturated monomer Xb having no aromatic ring in the molecule and having a hydrophilic group is preferably acrylic acid or methacrylic acid ester as a monomer unit having a hydroxy group. For example, acrylic acid (2-hydroxyethyl) , Acrylic acid (2-hydroxypropyl), acrylic acid (3-hydroxypropyl), acrylic acid (4-hydroxybutyl), acrylic acid (2-hydroxybutyl), or those obtained by replacing acrylic acid with methacrylic acid. Acrylic acid (2-hydroxyethyl) and methacrylic acid (2-hydroxyethyl), acrylic acid (2-hydroxypropyl), and acrylic acid (3-hydroxypropyl) are preferable.

  Xc is not particularly limited as long as it is an ethylenically unsaturated monomer other than Xa and Xb and copolymerizable, 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, more preferably in the range of 95: 5 to 75:25. P of Xc is 0-10. 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. When the molar composition ratio of Xb is large, the compatibility is deteriorated, but the effect of reducing Rt is high. Further, if the molar composition ratio of Xb exceeds the above range, haze tends to occur during film formation, and it is preferable to optimize these and determine the molar composition ratio of Xa and Xb.

  As for the molecular weight of the polymer X, the weight average molecular weight is from 5,000 to 30,000, more preferably from 8,000 to 25,000.

  By setting the weight average molecular weight to 5,000 or more, it is preferable because the cellulose ester film has advantages such as less dimensional change under high temperature and high humidity and less curling as a polarizing plate protective film. When the weight average molecular weight is 30000 or less, the compatibility with the cellulose ester is further improved, and bleeding out under high temperature and high humidity, and further haze generation immediately after film formation is suppressed.

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

  The measuring method of a weight average molecular weight can be based on the following method.

(Weight average molecular weight measurement method)
The weight average molecular weight Mw was measured using gel permeation chromatography.

  The measurement conditions are as follows.

Solvent: Methylene chloride Column: Shodex K806, K805, K803G (Used by connecting three Showa Denko Co., Ltd.)
Column temperature: 25 ° C
Sample concentration: 0.1% by mass
Detector: RI Model 504 (manufactured by GL Sciences)
Pump: L6000 (manufactured by Hitachi, Ltd.)
Flow rate: 1.0ml / min
Calibration curve: Standard polystyrene STK standard polystyrene (manufactured by Tosoh Corp.) Mw = 100000-500 calibration curves with 13 samples were used. Thirteen samples are used at approximately equal intervals.

  The polymer Y that can be preferably used in the present invention is a polymer having a weight average molecular weight of 500 or more and 3000 or less obtained by polymerizing an ethylenically unsaturated monomer Ya having no aromatic ring.

  A weight average molecular weight of 500 or more is preferable because the residual monomer of the polymer decreases. Moreover, it is preferable to set it as 3000 or less in order to maintain retardation value Rt fall performance.

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

  The polymer Y of the present invention is represented by the following general formula (2).

General formula (2)
− (Ya) _k − (Yb) _q −
More preferably, it is a polymer represented by the following general formula (2-1).

General formula (2-1)
_{- [CH 2 -C (-R 5} ) (- CO 2 R 6)] k - [Yb] q -
(In the formula, R ₅ represents H or CH _3. R ₆ represents an alkyl group or a cycloalkyl group having 1 to 12 carbon atoms. Yb represents a monomer unit copolymerizable with Ya. K and q Represents a molar composition ratio, where k ≠ 0 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, q is preferably 0-30.

  The ethylenically unsaturated monomer Ya constituting the polymer Y obtained by polymerizing an ethylenically unsaturated monomer having no aromatic ring is, for example, 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 (N-, i-), octyl acrylate (n-, i-), nonyl acrylate (n-, i-), myristyl acrylate (n-, i-), cyclohexyl acrylate, acrylic acid (2- Ethyl hexyl), acrylic acid (ε-caprolactone), acrylic acid (2-hydroxyethyl), acrylic acid (2-hydroxypropyl), acrylic acid (3-hydroxypropiyl) ), Acrylic acid (4-hydroxybutyl), acrylic acid (2-hydroxybutyl), methacrylic acid ester, the above acrylic acid ester changed to methacrylic acid ester; unsaturated acid, for example, acrylic acid, methacrylic acid And 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. Examples of vinyl esters include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl valerate, vinyl pivalate, and vinyl caproate. Vinyl caprate, vinyl laurate, vinyl myristate, vinyl palmitate, vinyl stearate, vinyl cyclohexanecarboxylate, vinyl octylate, vinyl methacrylate, vinyl crotonate, vinyl sorbate, vinyl cinnamate and the like are preferred. Yb may be plural.

  In order to synthesize the polymers X and Y, it is difficult to control the molecular weight in normal polymerization, and it is desirable to use a method that can make the molecular weights as uniform as possible without increasing the molecular weight. Such polymerization methods include a method using a peroxide polymerization initiator such as cumene peroxide and t-butyl hydroperoxide, a method using a polymerization initiator in a larger amount than normal polymerization, and a mercapto compound in addition to the polymerization initiator. And a method of using a chain transfer agent such as carbon tetrachloride, a method of using a polymerization terminator such as benzoquinone and dinitrobenzene in addition to the polymerization initiator, and further, Japanese Patent Application Laid-Open No. 2000-128911 or 2000-344823. Examples include a compound having one thiol group and a secondary hydroxy group, or a bulk polymerization method using a polymerization catalyst in which the compound and an organometallic compound are used in combination. Although it is preferably used, a compound having a thiol group and a secondary hydroxy group in the molecule is particularly used as a chain transfer agent. The polymerization method of use is preferred.

  In this case, the terminal of the polymer X and the polymer Y has a hydroxy group and a thioether resulting from the polymerization catalyst and the chain transfer agent. By this terminal residue, the compatibility between the polymers X and Y and the cellulose ester can be adjusted.

  The hydroxyl value (hydroxy group value) of the polymers X and Y is preferably 30 to 150 [mgKOH / g].

(Measurement method of hydroxyl value)
This measurement conforms to JIS K 0070 (1992). This hydroxyl value (hydroxy group value) is defined as the number of mg of potassium hydroxide required to neutralize acetic acid bonded to a hydroxy group when 1 g of a sample is acetylated. Specifically, sample Xg (about 1 g) is precisely weighed in a flask, and 20 ml of an acetylating reagent (a solution obtained by adding pyridine to 20 ml of acetic anhydride to 400 ml) is accurately added thereto. An air cooling tube is attached to the mouth of the flask and heated in a glycerin bath at 95-100 ° C.

  After 1 hour and 30 minutes, the mixture is cooled, 1 ml of purified water is added from an air condenser, and acetic anhydride is decomposed into acetic acid. Next, titration is performed with a 0.5 mol / L potassium hydroxide ethanol solution using a potentiometric titrator, and the inflection point of the obtained titration curve is set as the end point. Further, as a blank test, titration is performed without a sample, and an inflection point of the titration curve is obtained.

  The hydroxyl value (hydroxy group value) is calculated by the following formula.

Hydroxyl value (hydroxy group value) = {(BC) × f × 28.05 / X} + D
(Wherein B is the amount of 0.5 mol / L potassium hydroxide ethanol solution used in the blank test (ml), and C is the amount of 0.5 mol / L potassium hydroxide ethanol solution used in the titration (ml). F is a factor of 0.5 mol / L potassium hydroxide ethanol solution, D is an acid value, and 28.05 is 1/2 of 1 mol amount of potassium hydroxide 56.11)
All of the above-mentioned X polymer polymers Y have excellent compatibility with cellulose esters, excellent productivity without evaporation and volatilization, good retention as a protective film for polarizing plates, low moisture permeability, and excellent dimensional stability. ing.

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% = the mass of the polymer X / the mass of the cellulose ester × 100) and the content of the polymer Y is Yg (mass%),
Formula (i) 5 ≦ Xg + Yg ≦ 35 (mass%)
Formula (ii) 0.05 ≦ Yg / (Xg + Yg) ≦ 0.4
A preferable range of the formula (i) is 10 to 25% by mass.

  If 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 act to reduce the retardation value Rt. Moreover, if it is 35 mass% or less as a total amount, adhesiveness with polarizer PVA is favorable.

  The polymer X and the polymer Y can be directly added and dissolved as a material constituting the dope liquid described later, or can be added to the dope liquid after being previously dissolved in an organic solvent for dissolving the cellulose ester.

<polyester>
The cellulose ester film that can be used in the present invention preferably contains the following polyester.

(Polyester represented by 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).

General formula (3) B1- (GA-) _m G-B1
(In the formula, B1 represents a monocarboxylic acid, G represents a divalent alcohol, A represents a dibasic acid, and B1, G, and A do not contain an aromatic ring. M represents the number of repetitions. )
Formula _{(4) B2- (A-G-} ) n A-B2
(In the formula, B2 represents a monoalcohol, G represents a divalent alcohol, A represents a dibasic acid, and B2, G, and A do not contain an aromatic ring. N represents the number of repetitions.)
In the general formulas (3) and (4), B1 represents a monocarboxylic acid component, B2 represents a monoalcohol component, G represents a divalent alcohol component, A represents a dibasic acid component, and these are synthesized. It represents what has been done. B1, B2, G, and A are all characterized by containing no aromatic ring. m and n represent the number of repetitions.

  There is no restriction | limiting in particular as monocarboxylic acid represented by B1, Well-known aliphatic monocarboxylic acid, alicyclic monocarboxylic acid, etc. 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 fatty acid having a straight chain or a side chain having 1 to 32 carbon atoms can be preferably used. The number of carbon atoms is more preferably 1-20, and particularly preferably 1-12. When acetic acid is contained, the compatibility with the cellulose ester is increased, and it is also preferable to use a mixture of acetic acid and another monocarboxylic acid.

  Preferred aliphatic monocarboxylic acids include formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2-ethyl-hexanecarboxylic acid, undecylic acid, lauric acid, tridecyl Acids, myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, melicic acid, and laccelic acid, undecylenic acid And unsaturated fatty acids such as 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, an aliphatic saturated alcohol or aliphatic unsaturated alcohol having a straight chain or a side chain having 1 to 32 carbon atoms can be preferably used. The number of carbon atoms is more preferably 1-20, and particularly preferably 1-12.

  Examples of the divalent alcohol component represented by G include the following, but the present invention is not limited thereto. For example, ethylene glycol, diethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, 1,5-pentanediol, , 6-hexanediol, 1,5-pentylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, etc., among which 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 is more preferable. 1,4-butylene glycol 1,6-hexanediol, are used preferably diethylene glycol.

  The dibasic acid (dicarboxylic acid) component represented by A is preferably an aliphatic dibasic acid or an alicyclic dibasic acid. Examples of the aliphatic dibasic acid include malonic acid, succinic acid, glutaric acid, Adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedicarboxylic acid, dodecanedicarboxylic acid, etc., especially aliphatic dicarboxylic acids having 4 to 12 carbon atoms, at least one selected from these To do. That is, two or more dibasic acids may be used in combination.

  m and n represent the number of repetitions and are preferably 1 or more and 170 or less.

(Polyester represented by 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).

Formula (5) B1- (GA-) _m G-B1
(In the formula, B1 represents a monocarboxylic acid having 1 to 12 carbon atoms, G represents a divalent alcohol having 2 to 12 carbon atoms, and A represents a dibasic acid having 2 to 12 carbon atoms. B1, G , A does not contain an aromatic ring, and m represents the number of repetitions.)
Formula _{(6) B2- (A-G-} ) n A-B2
(In the formula, B2 represents a monoalcohol having 1 to 12 carbon atoms, G represents a divalent alcohol having 2 to 12 carbon atoms, and A represents a dibasic acid having 2 to 12 carbon atoms. B2, G, (A does not contain an aromatic ring. N represents the number of repetitions.)
In the general 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, and A represents 2 to 2 carbon atoms. Twelve dibasic acid components are represented and synthesized by them. B1, G, and A do not contain an aromatic ring. m and n represent the number of repetitions.

  B1 and B2 are synonymous with B1 and B2 in the general formula (3) or (4).

  G and A are alcohol components or dibasic acid components having 2 to 12 carbon atoms in G and A in the above general formula (3) or (4).

  The weight average molecular weight of the polyester is preferably 20000 or less, and more preferably 10,000 or less. In particular, polyesters having a weight average molecular weight of 500 to 10,000 have good compatibility with cellulose esters and are preferably used.

  Polycondensation of polyester is performed by a conventional method. For example, a direct reaction of the above dibasic acid and glycol, the above dibasic acid or an alkyl ester thereof, for example, a polyesterification reaction or transesterification reaction between a dibasic acid methyl ester and a glycol, or a hot melt condensation method, Alternatively, it can be easily synthesized by any method of dehydrohalogenation reaction between acid chloride of these acids and glycol, but polyester having a weight average molecular weight not so large is preferably by direct reaction.

  Polyester having a high distribution on the low molecular weight side has very good compatibility with the cellulose ester, and after forming the film, it is possible to obtain a cellulose ester film having low moisture permeability and high transparency. A conventional method can be used as a method for adjusting the molecular weight without particular limitation. For example, although depending on the polymerization conditions, the amount of these monovalent compounds can be controlled by a method of blocking the molecular ends with a monovalent acid or monovalent alcohol.

  In this case, a monovalent acid is preferable from the viewpoint of polymer stability. For example, acetic acid, propionic acid, butyric acid and the like can be mentioned, but during the polycondensation reaction, they are not distilled out of the system, but are stopped and such monovalent acids are removed out of the reaction system. Those that are easily removed are sometimes selected, but these may be mixed and used. In the case of a direct reaction, the weight average molecular weight can also be adjusted by measuring the timing at which the reaction is stopped by the amount of water distilled off during the reaction. In addition, it can be adjusted by biasing the number of moles of glycol or dibasic acid to be charged or by controlling the reaction temperature.

  The polyester that can be used in the present invention is preferably contained in an amount of 1 to 40% by mass relative to the cellulose ester, and the polyester represented by the general formula (5) or (6) is preferably contained in an amount of 2 to 30% by mass. . It is preferable to contain 5-15 mass% especially.

<Compound with furanose structure or pyranose structure>
The cellulose ester film that can be used in the present invention has at least one furanose structure or pyranose structure, and all or part of OH groups in a compound having 1 to 12 furanose structures or pyranose structures bonded thereto is esterified. And a compound.

  Examples of preferable “compounds 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. It is not limited to these.

  Glucose, galactose, mannose, fructose, xylose, arabinose, lactose, sucrose, cellobiose, cellotriose, maltotriose, raffinose and the like can be mentioned, and those having both a furanose structure and a pyranose structure are particularly preferable. An example is sucrose.

  As the monocarboxylic acid used for a compound having at least one furanose structure or pyranose structure and esterifying all or part of the OH group in the compound having 1 to 12 furanose structures or pyranose structures bonded thereto, There is no restriction | limiting, A well-known aliphatic monocarboxylic acid, alicyclic monocarboxylic acid, aromatic monocarboxylic acid etc. can be used. The carboxylic acid used may be one type or a mixture of two or more types.

  Preferred aliphatic monocarboxylic acids include acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2-ethyl-hexanecarboxylic acid, undecylic acid, lauric acid , Saturated fatty acids such as tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, melicic acid, and laccelic acid, Examples include 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 cyclopentane carboxylic acid, cyclohexane carboxylic acid, cyclooctane carboxylic acid, or derivatives thereof.

  Examples of preferred aromatic monocarboxylic acids include those in which an alkyl group or alkoxy group is introduced into the benzene ring of benzoic acid such as benzoic acid or toluic acid, cinnamic acid, benzylic acid, biphenylcarboxylic acid, naphthalenecarboxylic acid, tetralin An aromatic monocarboxylic acid having two or more benzene rings such as carboxylic acid, or a derivative thereof can be mentioned, and benzoic acid is particularly preferable.

  Details of the production methods of these compounds are described in JP-A Nos. 62-42996 and 10-237084.

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

<Sulfone compound>
In the following 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. Moreover, it is particularly preferable that the total number of carbon atoms of R ¹ , R ² and R ³ is 10 or more.

In the general formula (8), R ⁴ and R ⁵ each independently represents 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 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.

  Further, the alkyl group may be linear, branched or cyclic, and preferably has 1 to 25 carbon atoms, more preferably 6 to 25, and more preferably 6 to 20 (E.g., methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, amyl, isoamyl, t-amyl, hexyl, cyclohexyl, heptyl, octyl, bicyclooctyl, nonyl, adamantyl, decyl, t-octyl, undecyl, Dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, didecyl) are particularly preferred. As the aryl group, those having 6 to 30 carbon atoms are preferable, and those having 6 to 24 carbon atoms (for example, phenyl, biphenyl, terphenyl, naphthyl, binaphthyl, triphenylphenyl) are particularly preferable.

  Although the preferable example of a compound represented by General formula (7) or General formula (8) is shown below, this invention is not limited to these specific examples.

<First protective film>
In the first protective film of the present invention, the retardation value Ro in the in-plane direction satisfies the following general formula (i) in the measurement at an optical wavelength of 590 nm in an environment of a temperature of 23 ° C. and a relative humidity of 55% RH, The angle formed by the slow axis of the protective film 1 and the absorption axis of the polarizer is 45 ° ± 10 °.

General formula (i) 80 ≦ Ro ≦ 200
(Wherein, a _{Ro = (n x -n y)} × d, n x is a refractive index in a slow axis direction in a plane of the film, n _y is a refractive in a direction perpendicular to the slow axis in the film plane (Where d represents the thickness of the film (nm))
The birefringence and retardation value of the film can be measured using an automatic birefringence measuring apparatus (trade name KOBRA-21ADH manufactured by Oji Scientific Instruments), but is not limited thereto.

  Although the 1st protective film which concerns on this invention will not be limited if the phase difference Ro of an in-plane direction is a material in said range, It is preferable that it is a protective film which consists of a cellulose-ester film.

A more preferred cellulose ester has an acyl group having 2 to 4 carbon atoms as a substituent, the substitution degree of acetyl group is _Xac, and the substitution degree of propionyl group or butyryl group is _Ypb . the sum of the substitution degree and Y _pb of the substitution degree X _ac and professional and Pioniru group or butyryl group, a cellulose ester satisfies the following formula (a).

  In addition, it is preferable that the thickness direction retardation Rt is in the range of 100 ≦ Rt ≦ 300 in order to exhibit the effects of the present invention.

Formula (A) 2.2 ≦ (X _ac + Y _pb ) ≦ 2.55
Particularly preferred is a cellulose ester that simultaneously satisfies the above formula (A) and the following formula (B).

Formula (B) 1.0 ≦ X _ac ≦ 2.1, 0.1 ≦ Y _pb ≦ 1.55
The degree of substitution of these acyl groups can be measured according to the method prescribed in ASTM-D817-96. The portion not substituted with an acyl group is usually present as a hydroxy hydroxyl group.

  These cellulose esters can be synthesized by a known method.

  The cellulose which is the raw material of the cellulose ester used in the first protective film according to the present invention can be used in the same manner as the cellulose which is the raw material of the cellulose ester used in the second protective film. The molecular weight, Mw / Mn ratio, and measurement method of the cellulose ester used in the first protective film according to the present invention are the same as those of the second protective film.

  In the present invention, the angle between the slow axis of the first protective film and the absorption axis of the polarizer described later is 45 ° ± 10 °. For this configuration, the slow axis of the first protective film is preferably parallel or perpendicular to the longitudinal direction of the roll-shaped polarizing plate. From the viewpoint of ease of production, etc., it is preferably perpendicular to the longitudinal direction.

  By making the first protective film and the polarizer as described above, linearly polarized light that has passed through the polarizer from the light source side can be made into a circularly polarizing plate by the first protective film (ie, λ / 4 plate). It is. In addition, according to the configuration of the present invention, a roll-shaped polarizer in which the angle between the longitudinal direction and the absorption axis is substantially 45 °, and a roll-shaped λ in which the longitudinal direction and the slow axis are substantially perpendicular. A roll-shaped circularly polarizing plate can be easily produced by simply laminating a / 4 plate with a roll-to-roll.

  A circularly polarizing plate can be easily produced by roll-to-roll.

  In addition, by applying the circularly polarizing plate to the front of the 3D liquid crystal panel and combining it with the λ / 4 retardation plate on the viewing side, crosstalk when the head is tilted can be suppressed, and images with a stereoscopic effect can be obtained over a wide range. Can watch.

  Although the film thickness of a 1st protective film is not specifically limited, 10-200 micrometers is used. Preferably it is 10-100 micrometers, More preferably, it is 30-80 micrometers.

<Phase difference adjusting agent>
In the present invention, a phase difference adjusting agent can be used to adjust the phase difference. Although it does not specifically limit as a phase difference adjusting agent, The following polyester polyol can be used.

  The polyester polyol that can be used in the present invention is a polymer in which the terminal that can be obtained by the condensation reaction of a dibasic acid or an ester-forming derivative thereof and glycol becomes a hydroxy group (hydroxyl group). The ester-forming derivatives referred to here are esterified products of dibasic acids, dibasic acid chlorides, and anhydrides of dibasic acids.

  The polyester polyol is obtained by dehydration condensation reaction of an aromatic dibasic acid and glycol, addition of glycol to an aromatic anhydride dibasic acid and dehydration condensation reaction, or alcohol removal of an esterified product of an aromatic dibasic acid and glycol. It can be obtained by a condensation reaction.

  As the aromatic dibasic acid or an ester-forming derivative thereof, an aromatic dicarboxylic acid having 10 to 16 carbon atoms or an ester-forming derivative thereof can be used. For example, a benzene ring structure, a naphthalene ring structure, Dicarboxylic acids having an aromatic ring structure such as anthracene ring structure and ester-forming derivatives thereof can be used. For example, orthophthalic acid having a substituent, isophthalic acid having a substituent, terephthalic acid having a substituent, substituted Group-containing phthalic anhydride, 1,4-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 2,6 -Anthracene dicarboxylic acid and the like, esterified products thereof, acid chlorides, 1,8-naphtha Etc. can be mentioned acid anhydrides Njikarubon acid, they may have a substituent on the aromatic ring, can be used in combination use of two or more of these alone. 1,4-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid and esterified products thereof, 2,3-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid and esterified products thereof are preferable, and 2,6-naphthalenedicarboxylic acid and esterified products thereof are particularly preferable.

  The average of the carbon number of the dibasic acid of the polyester polyol means the carbon number of the dibasic acid when the polyester polyol is polymerized using a single dibasic acid. When the polyester polyol is polymerized using, it means the sum of the products of the carbon number of each dibasic acid and the molar fraction of the dibasic acid.

  In the present invention, it is important that the average number of carbon atoms of the dibasic acid used as a raw material for the polyester polyol is in the range of 10 to 16. If the average carbon number of the dibasic acid is 10 or more, the retardation is excellent. If the average carbon number is 16 or less, the compatibility with the cellulose ester is remarkably excellent. As a dibasic acid, Preferably the average of carbon number is 10-14, More preferably, the average of carbon number is 10-12.

  If the average carbon number is 10 to 16, the aromatic dibasic acid having 10 to 16 carbon atoms and the other dibasic acid can be used in combination.

  The dibasic acid that can be used in combination is preferably a dicarboxylic acid having 4 to 9 carbon atoms or an ester-forming derivative thereof. For example, succinic acid, glutaric acid, adipic acid, maleic acid, succinic anhydride, maleic anhydride, orthophthalic acid Examples thereof include acids, isophthalic acid, terephthalic acid, phthalic anhydride and the like, esterified products, and acid chlorides thereof.

  Examples of the glycol include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propanediol, 2-methyl 1,3-propanediol, 1,2-butanediol, 1,3- Butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, neopentyl glycol, 1,2-cyclopentanediol, 1,3-cyclopentanediol, 1,4-cyclohexanediol Can be used alone or in combination of two or more, among which ethylene glycol, diethylene glycol, 1,2-propylene glycol, 2-methyl 1,3-propanediol are preferred, more preferably ethylene glycol, diethylene glycol, 1,2- Russia is propylene glycol.

  The polyester polyol according to the present invention comprises the dibasic acid or ester-forming derivative thereof and glycol, if necessary, in the presence of an esterification catalyst, for example, within a temperature range of 180 to 250 ° C., for 10 to 25 hours, It can be produced by an esterification reaction by a known and conventional method.

  In conducting the esterification reaction, a solvent such as toluene or xylene may be used, but a method using no solvent or glycol used as a raw material as a solvent is preferable.

  As the esterification catalyst, for example, tetraisopropyl titanate, tetrabutyl titanate, p-toluenesulfonic acid, dibutyltin oxide and the like can be used. The esterification catalyst is preferably used in an amount of 0.01 to 0.5 parts by mass with respect to 100 parts by mass of the total amount of dibasic acids or their ester-forming derivatives.

  The molar ratio when the dibasic acid or ester-forming derivative thereof is reacted with the glycol must be a molar ratio in which the terminal group of the polyester becomes a hydroxy group (hydroxyl group). The glycol is 1.1 to 10 moles per mole of the functional derivative. Preferably, glycol is 1.5 to 7 moles with respect to 1 mole of dibasic acid or an ester-forming derivative thereof, and more preferably with respect to 1 mole of dibasic acid or an ester-forming derivative thereof. 2-5 moles of glycol.

  On the other hand, the content of the carboxyl group terminal in the polyester polyol is preferably low in order to reduce humidity stability. Specifically, the acid value is preferably 5.0 or less, more preferably 1.0 or less, and particularly preferably 0.5 or less.

  The acid value referred to here means the number of milligrams of potassium hydroxide necessary for neutralizing the acid (carboxy group present in the sample) contained in 1 g of the sample. The acid value is measured according to JIS K0070.

  The polyester polyol preferably has a hydroxy group (hydroxyl group) value (OHV) in the range of 35 mgKOH / g to 220 mgKOH / g. The hydroxy group (hydroxyl group) value referred to here is the number of milligrams of potassium hydroxide required to neutralize acetic acid bonded to the hydroxy group (hydroxyl group) when OH groups contained in 1 g of a sample are acetylated. Say. Acetic anhydride is used to acetylate OH groups in the sample, and unused acetic acid is titrated with a potassium hydroxide solution, and obtained from the difference from the initial titration value of acetic anhydride.

  The polyester polyol preferably has a hydroxy group (hydroxyl group) content of 70% or more. When the hydroxy group (hydroxyl group) content is low, the compatibility between the polyester polyol and the cellulose ester is lowered. For this reason, the hydroxy group (hydroxyl group) content is preferably 70% or more, more preferably 90% or more, and most preferably 99% or more.

  In the present invention, a compound having a hydroxy group (hydroxyl group) content of 50% or less is not included in the polyester polyol because one of the end groups is substituted with a group other than the hydroxy group (hydroxyl group).

  The hydroxy group (hydroxyl group) content can be determined by the following formula (A).

Formula (A): Y / X × 100 = hydroxy group (hydroxyl group) content (%)
X: Hydroxyl group (hydroxyl group) value (OHV) of the polyester polyol
Y: 1 / (number average molecular weight (Mn)) × 56 × 2 × 1000
The polyester polyol preferably has a number average molecular weight within a range of 300 to 3,000, and more preferably has a number average molecular weight of 350 to 2,000.

  Moreover, it is preferable that the dispersion degree of the molecular weight of the polyester polyol based on this invention is 1.0-3.0, and it is still more preferable that it is 1.0-2.0. If the degree of dispersion is within the above range, a polyester polyol having excellent compatibility with the cellulose ester can be obtained.

  The polyester polyol preferably contains 50% or more of a component having a molecular weight of 300 to 1800. By setting the number average molecular weight within the above range, the compatibility can be greatly improved.

  As a method for controlling the number average molecular weight, the degree of dispersion, and the component content within the above preferred range, 2 to 5 mol of glycol is used per 1 mol of dibasic acid or ester-forming derivative thereof, and unreacted glycol is used. A method of distilling off under reduced pressure is preferred. The temperature at which the solvent is distilled off under reduced pressure is preferably 100 to 200 ° C, more preferably 120 to 180 ° C, and particularly preferably 130 to 170 ° C. The degree of reduced pressure when the solvent is distilled off under reduced pressure is preferably 0.1 to 500 Torr, more preferably 0.5 to 200 Torr, and most preferably 1 to 100 Torr.

  The polyester polyol number average molecular weight (Mn) and dispersity can be measured using gel permeation chromatography (GPC).

  An example of measurement conditions is as follows, but is not limited to this, and an equivalent measurement method can be used.

Solvent: Tetrahydrofuran (THF)
Column: TSKgel G2000HXL (Tosoh Co., Ltd. uses two connected)
Column temperature: 40 ° C
Sample concentration: 0.1% by mass
Apparatus: HLC-8220 (manufactured by Tosoh Corporation)
Flow rate: 1.0ml / min
Calibration curve: A calibration curve by PStQuick F (manufactured by Tosoh Corporation) is used.

    In obtaining the effects of the present invention, the polyester polyol is preferably contained in the film in an amount of 5 to 30% by mass. More preferably, it is 5-20 mass%.

Specific examples of dibasic acids having 10 to 16 carbon atoms are shown below, but the present invention is not limited thereto.
(1) 2,6-naphthalenedicarboxylic acid (2) 2,3-naphthalenedicarboxylic acid (3) 2,6-anthracenedicarboxylic acid (4) 2,6-naphthalenedicarboxylic acid: succinic acid (75: 25-99: 1 molar ratio)
(5) 2,6-naphthalenedicarboxylic acid: terephthalic acid (50:50 to 99: 1 molar ratio)
(6) 2,3-naphthalenedicarboxylic acid: succinic acid (75:25 to 99: 1 molar ratio)
(7) 2,3-naphthalenedicarboxylic acid: terephthalic acid (50:50 to 99: 1 molar ratio)
(8) 2,6-anthracene dicarboxylic acid: succinic acid (50:50 to 99: 1 molar ratio) (9) 2,6-anthracene dicarboxylic acid: terephthalic acid (25:75 to 99: 1 molar ratio)
(10) 2,6-naphthalenedicarboxylic acid: adipic acid (67:33 to 99: 1 molar ratio)
(11) 2,3-naphthalenedicarboxylic acid: adipic acid (67:33 to 99: 1 molar ratio)
(12) 2,6-anthracene dicarboxylic acid: adipic acid (40:60 to 99: 1 molar ratio)
As the phase difference adjusting agent that can be used in the present invention, in addition to the above-mentioned polyester polyol, a compound having an octanol-water partition coefficient (log P) of 0 or more and less than 7 is used from the viewpoint of water solubility and orientation of the compound. Is also preferable.

  As the phase difference adjusting agent, for example, an ester compound represented by the following general formula (9) can be preferably used.

General formula (9) B- (GA) n-GB
(Wherein B is a hydroxy group or carboxylic acid residue, G is an alkylene glycol residue having 2 to 12 carbon atoms, an aryl glycol residue having 6 to 12 carbon atoms, or an oxyalkylene glycol residue having 4 to 12 carbon atoms) A represents an alkylenedicarboxylic acid residue having 4 to 12 carbon atoms or an aryldicarboxylic acid residue having 6 to 12 carbon atoms, and n represents an integer of 1 or more.)
In the general formula (9), a hydroxy group or carboxylic acid residue represented by B, an alkylene glycol residue, an oxyalkylene glycol residue or an aryl glycol residue represented by G, an alkylene dicarboxylic acid residue represented by A or It is composed of an aryl dicarboxylic acid residue and can be obtained by the same reaction as that of a normal ester compound.

  Examples of the carboxylic acid component of the ester compound represented by the general formula (9) include acetic acid, propionic acid, butyric acid, benzoic acid, p-tert-butylbenzoic acid, orthotoluic acid, metatoluic acid, p-toluic acid, and dimethylbenzoic acid. , Ethyl benzoic acid, normal propyl benzoic acid, aminobenzoic acid, acetoxybenzoic acid, aliphatic acid and the like, and these can be used as one kind or a mixture of two or more kinds, respectively.

  Examples of the alkylene glycol component having 2 to 12 carbon atoms of the ester compound represented by the general formula (9) include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, , 3-butanediol, 1,2-propanediol, 2-methyl 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl-1,3-propanediol ( Neopentyl glycol), 2,2-diethyl-1,3-propanediol (3,3-dimethylolpentane), 2-n-butyl-2-ethyl-1,3-propanediol (3,3-dimethylolheptane) ), 3-methyl-1,5-pentanediol 1,6-hexanediol, 2,2,4-trimethyl 1,3-pentanedioe , 2-ethyl 1,3-hexanediol, 2-methyl 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-octadecanediol, and the like. It is used as one kind or a mixture of two or more kinds.

  In particular, an alkylene glycol having 2 to 12 carbon atoms is particularly preferable because of excellent compatibility with a cellulose ester.

  Examples of the oxyalkylene glycol component having 4 to 12 carbon atoms of the ester compound represented by the general formula (9) include diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, and tripropylene glycol. Yes, these glycols can be used as one or a mixture of two or more.

  Examples of the alkylene dicarboxylic acid component having 4 to 12 carbon atoms of the ester compound represented by the general formula (9) include succinic acid, maleic acid, fumaric acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, and dodecane. There exist dicarboxylic acid etc., and these are each used as a 1 type, or 2 or more types of mixture. Examples of the arylene dicarboxylic acid component having 6 to 12 carbon atoms include phthalic acid, terephthalic acid, isophthalic acid, 1,5 naphthalene dicarboxylic acid, and 1,4 naphthalene dicarboxylic acid.

  The ester compound represented by the general formula (9) has a number average molecular weight of preferably 300 to 1500, more preferably 400 to 1000. The acid value is 0.5 mgKOH / g or less, the hydroxy group (hydroxyl group) value is 25 mgKOH / g or less, more preferably the acid value is 0.3 mgKOH / g or less, and the hydroxy group (hydroxyl group) value is 15 mgKOH / g or less. Is.

  Although the specific compound of the ester type compound represented by General formula (9) which can be used for this invention below is shown, this invention is not limited to this.

  The first protective film and the second protective film of the present invention preferably contain a retardation adjusting agent in an amount of 0.1 to 30% by mass of the protective film, and particularly preferably 0.5 to 10% by mass.

(Phase difference agent)
In the present invention, a retardation (also referred to as “retardation”) developing agent may be included. The retardation developing agent can be contained, for example, in a proportion of 0.5 to 10% by mass of the protective film, and is preferably contained in a proportion of 2 to 6% by mass. By employing a phase difference (retardation) developing agent, high retardation expression can be obtained at a low draw ratio. The type of retardation developing agent is not particularly defined, but examples thereof include those made of rod-like or discotic compounds. As the rod-like or discotic compound, a compound having at least two aromatic rings can be preferably used as a retardation developing agent. The addition amount of the retardation developing agent composed of the rod-shaped compound is preferably 0.5 to 10 parts by mass, and 2 to 6 parts by mass with respect to 100 parts by mass of the polymer component containing the cellulose ester. Is more preferable.

  The discotic retardation developing agent is preferably used in a range of 0.5 to 10 parts by mass, and in a range of 1 to 8 parts by mass with respect to 100 parts by mass of the polymer component containing the cellulose ester. It is more preferable to use in the range of 2 to 6 parts by mass.

  Two or more kinds of retardation developing agents may be used in combination.

  The phase difference (retardation) developing agent preferably has maximum absorption in the wavelength region of 250 to 400 nm, and preferably has substantially no absorption in the visible region.

  The discotic compound will be described. As the discotic compound, a compound having at least two aromatic rings can be used.

  Here, the “aromatic ring” includes an aromatic heterocycle in addition to an aromatic hydrocarbon ring.

  The aromatic hydrocarbon ring is particularly preferably a 6-membered ring (that is, a benzene ring).

  The aromatic heterocycle is generally an unsaturated heterocycle. The aromatic heterocycle is preferably a 5-membered ring, 6-membered ring or 7-membered ring, more preferably a 5-membered ring or 6-membered ring. Aromatic heterocycles generally have the most double bonds. As the hetero atom, a nitrogen atom, an oxygen atom and a sulfur atom are preferable, and a nitrogen atom is particularly preferable. Examples of aromatic heterocycles include furan ring, thiophene ring, pyrrole ring, oxazole ring, isoxazole ring, thiazole ring, isothiazole ring, imidazole ring, pyrazole ring, furazane ring, triazole ring, pyran ring, pyridine ring , Pyridazine ring, pyrimidine ring, pyrazine ring and 1,3,5-triazine ring.

  As the aromatic ring, a benzene ring, a condensed benzene ring, and biphenyls are preferable. In particular, a 1,3,5-triazine ring is preferably used. Specifically, for example, compounds disclosed in JP-A No. 2001-166144 are preferably used.

  The number of carbon atoms of the aromatic ring contained in the retardation developing agent is preferably 2-20, more preferably 2-12, further preferably 2-8, and 2-6. Most preferably.

  The bonding relationship between two aromatic rings can be classified into (a) when forming a condensed ring, (b) when directly connecting with a single bond, and (c) when connecting via a linking group (for aromatic rings). , Spiro bonds cannot be formed). The connection relationship may be any of (a) to (c).

  Examples of the condensed ring (a condensed ring of two or more aromatic rings) include an indene ring, a naphthalene ring, an azulene ring, a fluorene ring, a phenanthrene ring, an anthracene ring, an acenaphthylene ring, a biphenylene ring, a naphthacene ring, Pyrene ring, indole ring, isoindole ring, benzofuran ring, benzothiophene ring, indolizine ring, benzoxazole ring, benzothiazole ring, benzimidazole ring, benzotriazole ring, purine ring, indazole ring, chromene ring, quinoline ring, isoquinoline Ring, quinolidine ring, quinazoline ring, cinnoline ring, quinoxaline ring, phthalazine ring, pteridine ring, carbazole ring, acridine ring, phenanthridine ring, xanthene ring, phenazine ring, phenothiazine ring, phenoxathiin ring, phenoxazine ring and thiantole Ring is included. Naphthalene ring, azulene ring, indole ring, benzoxazole ring, benzothiazole ring, benzimidazole ring, benzotriazole ring and quinoline ring are preferred.

  The single bond (b) is preferably a bond between carbon atoms of two aromatic rings. Two aromatic rings may be bonded by two or more single bonds to form an aliphatic ring or a non-aromatic heterocyclic ring between the two aromatic rings.

The linking group in (c) is also preferably bonded to carbon atoms of two aromatic rings. The linking group is preferably an alkylene group, an alkenylene group, an alkynylene group, —CO—, —O—, —NH—, —S—, or a combination thereof. Examples of linking groups composed of combinations are shown below. In addition, the relationship between the left and right in the following examples of the linking group may be reversed.
c1: -CO-O-
c2: —CO—NH—
c3: -alkylene-O-
c4: —NH—CO—NH—
c5: —NH—CO—O—
c6: —O—CO—O—
c7: -O-alkylene-O-
c8: -CO-alkenylene-
c9: -CO-alkenylene-NH-
c10: -CO-alkenylene-O-
c11: -alkylene-CO-O-alkylene-O-CO-alkylene-
c12: -O-alkylene-CO-O-alkylene-O-CO-alkylene-O-
c13: -O-CO-alkylene-CO-O-
c14: -NH-CO-alkenylene-
c15: -O-CO-alkenylene-
The aromatic ring and the linking group may have a substituent.

  Examples of substituents include halogen atoms (F, Cl, Br, I), hydroxy groups, carboxy groups, cyano groups, amino groups, nitro groups, sulfo groups, carbamoyl groups, sulfamoyl groups, ureido groups, alkyl groups, alkenyls. Group, alkynyl group, aliphatic acyl group, aliphatic acyloxy group, alkoxy group, alkoxycarbonyl group, alkoxycarbonylamino group, alkylthio group, alkylsulfonyl group, aliphatic amide group, aliphatic sulfonamido group, aliphatic substituted amino group An aliphatic substituted carbamoyl group, an aliphatic substituted sulfamoyl group, an aliphatic substituted ureido group, and a non-aromatic heterocyclic group.

  It is preferable that the alkyl group has 1 to 8 carbon atoms. A chain alkyl group is preferable to a cyclic alkyl group, and a linear alkyl group is particularly preferable. The alkyl group may further have a substituent (for example, a hydroxy group, a carboxy group, an alkoxy group, an alkyl-substituted amino group). Examples of alkyl groups (including substituted alkyl groups) include methyl, ethyl, n-butyl, n-hexyl, 2-hydroxyethyl, 4-carboxybutyl, 2-methoxyethyl and 2-methoxyethyl. Each group of a diethylaminoethyl group is included.

  The alkenyl group preferably has 2 to 8 carbon atoms. A chain alkenyl group is preferable to a cyclic alkenyl group, and a linear alkenyl group is particularly preferable. The alkenyl group may further have a substituent. Examples of the alkenyl group include a vinyl group, an allyl group, and a 1-hexenyl group.

  The alkynyl group preferably has 2 to 8 carbon atoms. A chain alkynyl group is preferable to a cyclic alkynyl group, and a linear alkynyl group is particularly preferable. The alkynyl group may further have a substituent. Examples of the alkynyl group include ethynyl group, 1-butynyl group and 1-hexynyl group.

  The number of carbon atoms in the aliphatic acyl group is preferably 1-10. Examples of the aliphatic acyl group include an acetyl group, a propanoyl group, and a butanoyl group.

  The number of carbon atoms in the aliphatic acyloxy group is preferably 1-10. Examples of the aliphatic acyloxy group include an acetoxy group.

  The number of carbon atoms of the alkoxy group is preferably 1-8. The alkoxy group may further have a substituent (for example, an alkoxy group). Examples of the alkoxy group (including a substituted alkoxy group) include a methoxy group, an ethoxy group, a butoxy group, and a methoxyethoxy group.

  The number of carbon atoms of the alkoxycarbonyl group is preferably 2-10. Examples of the alkoxycarbonyl group include a methoxycarbonyl group and an ethoxycarbonyl group.

  The number of carbon atoms of the alkoxycarbonylamino group is preferably 2-10. Examples of the alkoxycarbonylamino group include a methoxycarbonylamino group and an ethoxycarbonylamino group.

  The alkylthio group preferably has 1 to 12 carbon atoms. Examples of the alkylthio group include a methylthio group, an ethylthio group, and an octylthio group.

  The alkylsulfonyl group preferably has 1 to 8 carbon atoms. Examples of the alkylsulfonyl group include a methanesulfonyl group and an ethanesulfonyl group.

  The number of carbon atoms in the aliphatic amide group is preferably 1-10. Examples of the aliphatic amide group include acetamide.

  The number of carbon atoms of the aliphatic sulfonamide group is preferably 1-8. Examples of the aliphatic sulfonamido group include a methanesulfonamido group, a butanesulfonamido group, and an n-octanesulfonamido group.

  The number of carbon atoms of the aliphatic substituted amino group is preferably 1-10. Examples of the aliphatic substituted amino group include a dimethylamino group, a diethylamino group, and a 2-carboxyethylamino group.

  The number of carbon atoms in the aliphatic substituted carbamoyl group is preferably 2-10. Examples of the aliphatic substituted carbamoyl group include a methylcarbamoyl group and a diethylcarbamoyl group.

  The number of carbon atoms in the aliphatic substituted sulfamoyl group is preferably 1-8. Examples of the aliphatic substituted sulfamoyl group include a methylsulfamoyl group and a diethylsulfamoyl group.

  The number of carbon atoms in the aliphatic substituted ureido group is preferably 2-10. Examples of the aliphatic substituted ureido group include a methylureido group.

  Examples of the non-aromatic heterocyclic group include a piperidino group and a morpholino group.

  The molecular weight of the retardation developing agent is preferably 300 to 800.

  It is preferable to use a triazine compound represented by the following general formula (10) as the discotic compound.

In the general formula (10), each R ¹ independently represents an aromatic ring or a heterocyclic ring having a substituent in at least one of the ortho position, the meta position, and the para position.

X represents each independently a single bond or NR < ² >-. Here, each R ² independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, an alkenyl group, an aryl group, or a heterocyclic group.

The aromatic ring represented by R ¹ is preferably phenyl or naphthyl, and particularly preferably phenyl. The aromatic ring represented by R ¹ may have at least one substituent at any substitution position. Examples of the substituent include a halogen atom, hydroxy group, cyano group, nitro group, carboxy group, alkyl group, alkenyl group, aryl group, alkoxy group, alkenyloxy group, aryloxy group, acyloxy group, alkoxycarbonyl group, Alkenyloxycarbonyl group, aryloxycarbonyl group, sulfamoyl group, alkyl-substituted sulfamoyl group, alkenyl-substituted sulfamoyl group, aryl-substituted sulfamoyl group, sulfonamide group, carbamoyl, alkyl-substituted carbamoyl group, alkenyl-substituted carbamoyl group, aryl-substituted carbamoyl group, amide Groups, alkylthio groups, alkenylthio groups, arylthio groups and acyl groups.

The heterocyclic group represented by R ¹ preferably has aromaticity. The heterocycle having aromaticity is generally an unsaturated heterocycle, preferably a heterocycle having the largest number of double bonds. The heterocyclic ring is preferably a 5-membered ring, 6-membered ring or 7-membered ring, more preferably a 5-membered ring or 6-membered ring, and most preferably a 6-membered ring. The hetero atom of the heterocyclic ring is preferably a nitrogen atom, a sulfur atom or an oxygen atom, and particularly preferably a nitrogen atom. As the heterocyclic ring having aromaticity, a pyridine ring (2-pyridyl or 4-pyridyl as the heterocyclic group) is particularly preferable. The heterocyclic group may have a substituent. Examples of the substituent of the heterocyclic group are the same as the examples of the substituent of the aryl moiety.

  When X is a single bond, the heterocyclic group is preferably a heterocyclic group having a free valence on the nitrogen atom. The heterocyclic group having a free valence on the nitrogen atom is preferably a 5-membered ring, 6-membered ring or 7-membered ring, more preferably a 5-membered ring or 6-membered ring, and a 5-membered ring. Is most preferred. The heterocyclic group may have a plurality of nitrogen atoms. Further, the heterocyclic group may have a hetero atom other than the nitrogen atom (for example, O, S). Examples of heterocyclic groups having free valences on nitrogen atoms are shown below.

The alkyl group represented by R ² may be a cyclic alkyl group or a chain alkyl group, but a chain alkyl group is preferable, and a linear alkyl group is more preferable than a branched chain alkyl group. preferable.

  The number of carbon atoms in the alkyl group is preferably 1-30, more preferably 1-20, further preferably 1-10, still more preferably 1-8, and 1-6. Most preferred. The alkyl group may have a substituent. Examples of the substituent include a halogen atom, an alkoxy group (for example, methoxy group, ethoxy group) and an acyloxy group (for example, acryloyloxy group, methacryloyloxy group).

The alkenyl group represented by R ² may be a cyclic alkenyl group or a chain alkenyl group, but preferably represents a chain alkenyl group, and is a straight chain alkenyl group rather than a branched chain alkenyl group. More preferably it represents a group. The number of carbon atoms in the alkenyl group is preferably 2 to 30, more preferably 2 to 20, still more preferably 2 to 10, still more preferably 2 to 8, 6 is most preferred. The alkenyl group may have a substituent. Examples of the substituent are the same as those of the alkyl group described above.

The aromatic ring group and heterocyclic group represented by R ² are the same as the aromatic ring and heterocyclic ring represented by R ¹ , and the preferred range is also the same. The aromatic ring group and the heterocyclic group may further have a substituent, and examples of the substituent are the same as those of the aromatic ring and heterocyclic ring of R ¹ .

  As the discotic compound, a triphenylene compound represented by the following general formula (11) can also be preferably used.

In the general formula (11), R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ each independently represent a hydrogen atom or a substituent.

The substituent represented by each of R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ is an alkyl group (preferably having 1 to 40 carbon atoms, more preferably 1 to 30 carbon atoms, and particularly preferably carbon number). 1-20 alkyl groups, such as methyl, ethyl, isopropyl, tert-butyl, n-octyl, n-decyl, n-hexadecyl, cyclopropyl, cyclopentyl, cyclohexyl, etc. ), An alkenyl group (preferably an alkenyl group having 2 to 40 carbon atoms, more preferably 2 to 30 carbon atoms, particularly preferably 2 to 20 carbon atoms, such as a vinyl group, an allyl group, 2- Butenyl group, 3-pentenyl group and the like), alkynyl group (preferably 2 to 40 carbon atoms, more preferably 2 to 30 carbon atoms, particularly preferably 2 carbon atoms). -20 alkynyl group, for example, propargyl group, 3-pentynyl group, etc., aryl group (preferably 6-30 carbon atoms, more preferably 6-20 carbon atoms, particularly preferably 6-6 carbon atoms). 12 aryl groups, for example, phenyl group, p-methylphenyl group, naphthyl group, etc., substituted or unsubstituted amino group (preferably having 0 to 40 carbon atoms, more preferably 0 to 30 carbon atoms). And particularly preferably an amino group having 0 to 20 carbon atoms, such as an unsubstituted amino group, a methylamino group, a dimethylamino group, a diethylamino group, and an anilino group), an alkoxy group (preferably having a carbon number of 1 to 40, more preferably an alkoxy group having 1 to 30 carbon atoms, particularly preferably 1 to 20 carbon atoms, such as a methoxy group, an ethoxy group, And the like, and an aryloxy group (preferably an aryloxy group having 6 to 40 carbon atoms, more preferably 6 to 30 carbon atoms, particularly preferably 6 to 20 carbon atoms, such as a phenyloxy group, 2-naphthyloxy group and the like), an acyl group (preferably 1 to 40 carbon atoms, more preferably 1 to 30 carbon atoms, particularly preferably an acyl group having 1 to 20 carbon atoms, for example, an acetyl group, A benzoyl group, a formyl group, a pivaloyl group, and the like), an alkoxycarbonyl group (preferably an alkoxycarbonyl group having 2 to 40 carbon atoms, more preferably 2 to 30 carbon atoms, particularly preferably 2 to 20 carbon atoms, For example, methoxycarbonyl group, ethoxycarbonyl group, etc.), aryloxycarbonyl group (preferably carbon An aryloxycarbonyl group having 7 to 40 carbon atoms, more preferably 7 to 30 carbon atoms, particularly preferably 7 to 20 carbon atoms, such as a phenyloxycarbonyl group, and an acyloxy group (preferably 2 to 2 carbon atoms). 40, more preferably an acyloxy group having 2 to 30 carbon atoms, particularly preferably 2 to 20 carbon atoms, such as an acetoxy group and a benzoyloxy group), an acylamino group (preferably having 2 to 40 carbon atoms, More preferably, it is an acylamino group having 2 to 30 carbon atoms, particularly preferably 2 to 20 carbon atoms, and examples thereof include an acetylamino group and a benzoylamino group), an alkoxycarbonylamino group (preferably having 2 to 40 carbon atoms, More preferred is an alkoxycarbonyl group having 2 to 30 carbon atoms, particularly preferably 2 to 20 carbon atoms. A mino group such as a methoxycarbonylamino group), an aryloxycarbonylamino group (preferably having 7 to 40 carbon atoms, more preferably 7 to 30 carbon atoms, particularly preferably 7 to 20 carbon atoms). An oxycarbonylamino group such as a phenyloxycarbonylamino group), a sulfonylamino group (preferably having 1 to 40 carbon atoms, more preferably 1 to 30 carbon atoms, and particularly preferably 1 to 20 carbon atoms). A sulfonylamino group, for example, a methanesulfonylamino group, a benzenesulfonylamino group, and the like; a sulfamoyl group (preferably having 0 to 40 carbon atoms, more preferably 0 to 30 carbon atoms, and particularly preferably 0 to 0 carbon atoms). 20 sulfamoyl groups such as sulfamoyl group, methylsulfur group A moyl group, a dimethylsulfamoyl group, a phenylsulfamoyl group and the like), a carbamoyl group (preferably having 1 to 40 carbon atoms, more preferably 1 to 30 carbon atoms, and particularly preferably 1 to 20 carbon atoms). A non-substituted carbamoyl group, a methylcarbamoyl group, a diethylcarbamoyl group, a phenylcarbamoyl group, etc., an alkylthio group (preferably having 1 to 40 carbon atoms, more preferably 1 to 30 carbon atoms, especially Preferably it is C1-C20, for example, a methylthio group, an ethylthio group, a propylthio group, a butylthio group, a pentylthio group, a hexylthio group, a heptylthio group, an octylthio group etc. are mentioned, An arylthio group (preferably 6 carbon atoms) ~ 40, more preferably 6-30 carbon atoms, especially preferred Is a sulfonyl group having 1 to 20 carbon atoms, such as a phenylthio group, preferably a sulfonyl group (preferably having 1 to 40 carbon atoms, more preferably 1 to 30 carbon atoms, and particularly preferably 1 to 20 carbon atoms). , For example, a mesyl group, a tosyl group, etc.), a sulfinyl group (preferably a sulfinyl group having 1 to 40 carbon atoms, more preferably 1 to 30 carbon atoms, particularly preferably 1 to 20 carbon atoms, A methanesulfinyl group, a benzenesulfinyl group and the like), a ureido group (preferably a ureido group having 1 to 40 carbon atoms, more preferably 1 to 30 carbon atoms, and particularly preferably 1 to 20 carbon atoms). Substituted ureido group, methylureido group, phenylureido group, etc.), phosphoric acid amide group (preferably having 1 to 40 carbon atoms) More preferably, it is a phosphoric acid amide group having 1 to 30 carbon atoms, particularly preferably 1 to 20 carbon atoms, and examples thereof include a diethylphosphoric acid amide group and a phenylphosphoric acid amide group), a hydroxy group, a mercapto group, Halogen atom (for example, fluorine atom, chlorine atom, bromine atom, iodine atom), cyano group, sulfo group, carboxy group, nitro group, hydroxamic acid group, sulfino group, hydrazino group, imino group, heterocyclic group (preferably carbon number) 1-30, more preferably 1-12, for example, a heterocyclic group having a heteroatom such as a nitrogen atom, oxygen atom, sulfur atom, etc., for example, an imidazolyl group, a pyridyl group, a quinolyl group, Furyl group, piperidyl group, morpholino group, benzoxazolyl group, benzimidazolyl group, benzthiazolyl group, 1,3,5- A silyl group (preferably 3 to 40 carbon atoms, more preferably 3 to 30 carbon atoms, and particularly preferably 3 to 24 carbon atoms). A phenylsilyl group, etc.). These substituents may be further substituted with these substituents. Moreover, when it has two or more substituents, they may be the same or different. If possible, they may be bonded to each other to form a ring.

The substituent represented by each of R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ is preferably an alkyl group, an aryl group, a substituted or unsubstituted amino group, an alkoxy group, an alkylthio group or a halogen atom. is there.

  Although the specific example of a compound represented by General formula (11) below is given, it is not limited to this.

  The compound represented by the general formula (10) is, for example, a method described in JP-A No. 2003-344655, and the compound represented by the general formula (11) is, for example, a method described in JP-A-2005-134484. Can be synthesized by a known method.

  In the present invention, rod-like compounds having a linear molecular structure can be preferably used in addition to the above-mentioned discotic compounds. The linear molecular structure means that the molecular structure of the rod-like compound is linear in the most thermodynamically stable structure. The most thermodynamically stable structure can be obtained by crystal structure analysis or molecular orbital calculation. For example, molecular orbital calculation is performed using molecular orbital calculation software (for example, WinMOPAC2000, manufactured by Fujitsu Limited), and a molecular structure that minimizes the heat of formation of a compound can be obtained. The molecular structure being linear means that in the thermodynamically most stable structure obtained by calculation as described above, the angle of the main chain constituting the molecular structure is 140 degrees or more.

  As the rod-shaped compound having at least two aromatic rings, a compound represented by the following general formula (12) is preferable.

Formula (12): Ar ₁ -L ₁ -Ar ₂
In the general formula (12), Ar ₁ and Ar ₂ are each independently an aromatic group. Here, the aromatic group includes an aryl group (aromatic hydrocarbon group), a substituted aryl group, an aromatic heterocyclic group, and a substituted aromatic heterocyclic group.

  An aryl group and a substituted aryl group are more preferable than an aromatic heterocyclic group and a substituted aromatic heterocyclic group. The heterocyclic ring of the aromatic heterocyclic group is generally unsaturated. The aromatic heterocycle is preferably a 5-membered ring, 6-membered ring or 7-membered ring, more preferably a 5-membered ring or 6-membered ring. Aromatic heterocycles generally have the most double bonds. As a hetero atom, a nitrogen atom, an oxygen atom or a sulfur atom is preferable, and a nitrogen atom or a sulfur atom is more preferable.

  As the aromatic ring of the aromatic group, a benzene ring, a furan ring, a thiophene ring, a pyrrole ring, an oxazole ring, a thiazole ring, an imidazole ring, a triazole ring, a pyridine ring, a pyrimidine ring and a pyrazine ring are preferable, and a benzene ring is particularly preferable. .

  Examples of the substituent of the substituted aryl group and the substituted aromatic heterocyclic group include a halogen atom (F, Cl, Br, I), a hydroxy group, a carboxy group, a cyano group, an amino group, an alkylamino group (for example, methyl Amino group, ethylamino group, butylamino group, dimethylamino group), nitro group, sulfo group, carbamoyl group, alkylcarbamoyl group (for example, N-methylcarbamoyl group, N-ethylcarbamoyl group, N, N-) Dimethylcarbamoyl group), sulfamoyl group, alkylsulfamoyl group (eg, N-methylsulfamoyl group, N-ethylsulfamoyl group, N, N-dimethylsulfamoyl group), ureido Group, alkylureido group (for example, N-methylureido group, N, N-dimethylureido group, N, N, N′-trimethyl) Each group of raid group), alkyl group (for example, methyl group, ethyl group, propyl group, butyl group, pentyl group, heptyl group, octyl group, isopropyl group, s-butyl group, tert-amyl group, cyclohexyl group, cyclopentyl) Group), alkenyl group (for example, vinyl group, allyl group, hexenyl group), alkynyl group (for example, ethynyl group, butynyl group), acyl group (for example, formyl group, acetyl group, butyryl group, Hexanoyl group, lauryl group), acyloxy group (for example, acetoxy group, butyryloxy group, hexanoyloxy group, lauryloxy group), alkoxy group (for example, methoxy group, ethoxy group, propoxy group, butoxy group) , Pentyloxy group, heptyloxy group, octyloxy group), aryloxy (For example, phenoxy group), alkoxycarbonyl group (for example, methoxycarbonyl group, ethoxycarbonyl group, propoxycarbonyl group, butoxycarbonyl group, pentyloxycarbonyl group, heptyloxycarbonyl group), aryloxycarbonyl group (for example, Phenoxycarbonyl group), alkoxycarbonylamino group (for example, butoxycarbonylamino group, hexyloxycarbonylamino group), alkylthio group (for example, methylthio group, ethylthio group, propylthio group, butylthio group, pentylthio group, heptylthio group, octylthio group) Each group), arylthio group (for example, phenylthio group), alkylsulfonyl group (for example, methylsulfonyl group, ethylsulfonyl group, propylsulfonyl group, butylsulfonyl group) , Pentylsulfonyl group, heptylsulfonyl group, octylsulfonyl group), amide group (for example, acetamido group, butyramide group, hexylamide group, laurylamide group) and non-aromatic heterocyclic group (for example, Morpholyl group, pyrazinyl group).

  Among these, preferable substituents include halogen atoms, cyano groups, carboxy groups, hydroxy groups, amino groups, alkylamino groups, acyl groups, acyloxy groups, amide groups, alkoxycarbonyl groups, alkoxy groups, alkylthio groups, and alkyl groups. Can be mentioned.

  The alkyl moiety of the alkylamino group, alkoxycarbonyl group, alkoxy group, and alkylthio group and the alkyl group may further have a substituent. Examples of the alkyl moiety and the substituent of the alkyl group include a halogen atom, hydroxy group, carboxy group, cyano group, amino group, alkylamino group, nitro group, sulfo group, carbamoyl group, alkylcarbamoyl group, sulfamoyl group, alkylsulfur group. Famoyl group, ureido group, alkylureido group, alkenyl group, alkynyl group, acyl group, acyloxy group, alkoxy group, aryloxy group, alkoxycarbonyl group, aryloxycarbonyl group, alkoxycarbonylamino group, alkylthio group, arylthio group, An alkylsulfonyl group, an amide group and a non-aromatic heterocyclic group are included. As the substituent for the alkyl moiety and the alkyl group, a halogen atom, a hydroxy group, an amino group, an alkylamino group, an acyl group, an acyloxy group, an acylamino group, an alkoxycarbonyl group, and an alkoxy group are preferable.

In General Formula (12), L ₁ is a divalent linking group selected from an alkylene group, an alkenylene group, an alkynylene group, —O—, —CO—, and a group thereof.

  The alkylene group may have a cyclic structure. As the cyclic alkylene group, cyclohexylene is preferable, and 1,4-cyclohexylene is particularly preferable. As the chain alkylene group, a linear alkylene group is more preferable than a branched alkylene group.

  The number of carbon atoms of the alkylene group is preferably 1-20, more preferably 1-15, still more preferably 1-10, still more preferably 1-8, and most preferably 1-6. It is.

  The alkenylene group and the alkynylene group preferably have a chain structure rather than a cyclic structure, and more preferably have a linear structure rather than a branched chain structure.

  The alkenylene group and the alkynylene group preferably have 2 to 10 carbon atoms, more preferably 2 to 8, more preferably 2 to 6, still more preferably 2 to 4, and most preferably 2. (Vinylene group or ethynylene group).

  The arylene group preferably has 6 to 20 carbon atoms, more preferably 6 to 16, and still more preferably 6 to 12.

In the molecular structure of the general formula (12), the angle formed by Ar ₁ and Ar ₂ across L ₁ is preferably 140 degrees or more.

  As the rod-like compound, a compound represented by the following formula (13) is more preferable.

Formula _{(13): Ar 1 -L 2} -X-L 3 -Ar 2
In the general formula (13), Ar ₁ and Ar ₂ are each independently an aromatic group. The definition and examples of the aromatic group are the same as those of Ar ₁ and Ar _{2 in} the general formula (12).

In General Formula (13), L ₂ and L ₃ are each independently a divalent linking group selected from an alkylene group, —O—, —CO—, and a group consisting of a combination thereof.

  The alkylene group preferably has a chain structure rather than a cyclic structure, and more preferably has a linear structure rather than a branched chain structure.

  The alkylene group preferably has 1 to 10 carbon atoms, more preferably 1 to 8, more preferably 1 to 6, still more preferably 1 to 4, and 1 or 2 (methylene group). Or an ethylene group) is most preferable.

L ₂ and L ₃ are particularly preferably —O—CO— or CO—O—.

  In General formula (13), X is a 1, 4- cyclohexylene group, vinylene group, or an ethynylene group.

  Specific examples of the compound represented by the general formula (12) or (13) include compounds described in [Chemical Formula 1] to [Chemical Formula 11] of JP-A No. 2004-109657.

  Two or more rod-shaped compounds whose maximum absorption wavelength (λmax) is longer than 250 nm in the ultraviolet absorption spectrum of the solution may be used in combination.

  The rod-like compound can be synthesized with reference to methods described in literature. As literature, Mol. Cryst. Liq. Cryst. 53, 229 (1979), 89, 93 (1982), 145, 111 (1987), 170, 43 (1989), J. Am. Am. Chem. Soc. 113, p. 1349 (1991), p. 118, p. 5346 (1996), p. 92, p. 1582 (1970). Org. Chem. 40, 420 pages (1975), Tetrahedron, Vol. 48, No. 16, page 3437 (1992).

  Moreover, you may use the rod-shaped aromatic compound of the 11-11 pages of Unexamined-Japanese-Patent No. 2004-50516 as said retardation (retardation) developing agent.

  When the optical film is produced by a solvent cast method, the retardation developing agent may be added to the dope. The addition may be performed at any timing. For example, a retardation developing agent may be dissolved in an organic solvent such as alcohol, methylene chloride, dioxolane, etc., and then added to the cellulose ester solution (dope). Or may be added directly into the dope composition.

  In addition, specific examples of preferable compounds of rod-like compounds other than those described in the above-mentioned publications are shown below.

  The specific examples (1) to (34), (41), and (42) have two asymmetric carbon atoms at the 1-position and the 4-position of the cyclohexane ring. However, since the specific examples (1), (4) to (34), (41), and (42) have a symmetrical meso type molecular structure, there are no optical isomers (optical activity), and geometric isomers (trans Type and cis type). The trans type (1-trans) and cis type (1-cis) of specific example (1) are shown below.

  As described above, the rod-like compound preferably has a linear molecular structure. Therefore, the trans type is preferable to the cis type.

  Specific examples (2) and (3) have optical isomers (a total of four isomers) in addition to geometric isomers. As for geometric isomers, the trans type is similarly preferable to the cis type. The optical isomer is not particularly superior or inferior, and may be D, L, or a racemate.

  In specific examples (43) to (45), the central vinylene bond includes a trans type and a cis type. For the same reason as above, the trans type is preferable to the cis type.

<Additives for first protective film and second protective film>
The cellulose ester film preferably used for the first protective film and the second protective film can contain an additive that can be added to a normal cellulose ester film.

  Examples of these additives include plasticizers, ultraviolet absorbers, and fine particles.

  The plasticizer that can be used in the present invention is not particularly limited, but preferably a polycarboxylic acid ester plasticizer, a glycolate plasticizer, a phthalate ester plasticizer, a fatty acid ester plasticizer, and a polyvalent plasticizer. It is selected from alcohol ester plasticizers, polyester plasticizers, acrylic plasticizers and the like. Of these, when two or more plasticizers are used, at least one plasticizer is preferably a polyhydric alcohol ester plasticizer.

  The polyhydric alcohol ester plasticizer is a plasticizer comprising an ester of a dihydric or higher aliphatic polyhydric alcohol and a monocarboxylic acid, and preferably has an aromatic ring or a cycloalkyl ring in the molecule. Preferably it is a 2-20 valent aliphatic polyhydric alcohol ester.

  The ultraviolet absorber that can be used in the present invention aims to improve durability by absorbing ultraviolet rays of 400 nm or less, and preferably has a transmittance of 10% or less at a wavelength of 370 nm. More preferably, it is 5% or less, and further preferably 2% or less.

  Although the ultraviolet absorber used in the present invention is not particularly limited, for example, oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, triazine compounds, nickel complex compounds, inorganic powders Examples include the body. It is good also as a polymer type ultraviolet absorber.

  As fine particles used in the present invention, examples of inorganic compounds include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, and hydrated silicic acid. Mention may be made of calcium, aluminum silicate, magnesium silicate and calcium phosphate. Fine particles containing silicon are preferable in terms of low turbidity, and silicon dioxide is particularly preferable.

  The average primary particle size of the fine particles is preferably 5 to 50 nm, and more preferably 7 to 20 nm. These are preferably contained mainly as secondary aggregates having a particle size of 0.05 to 0.3 μm. The content of these fine particles in the cellulose ester film is preferably 0.05 to 1% by mass, particularly preferably 0.1 to 0.5% by mass. In the case of a cellulose ester film having a multilayer structure by the co-casting method, it is preferable to contain fine particles of this addition amount on the surface.

  Silicon dioxide fine particles are commercially available, for example, under the trade names Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600 (above Nippon Aerosil Co., Ltd.). it can.

  Zirconium oxide fine particles 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 silicone resin, fluororesin, and acrylic resin. Silicone resins are preferable, and those having a three-dimensional network structure are particularly preferable. For example, Tospearl 103, 105, 108, 120, 145, 3120, and 240 (manufactured by Toshiba Silicone Co., Ltd.) It is marketed by name and can be used.

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

(Polarizing plate protective film manufacturing method)
Next, the manufacturing method of the cellulose-ester film which forms preferably the 2nd protective film (electrode side) and 1st protective film (non-electrode side) of this invention is demonstrated.

  The cellulose ester film is preferably a cellulose ester film produced by a solution casting method or a melt casting method.

  The cellulose ester film is produced by dissolving a cellulose ester, a compound having negative orientation birefringence and an additive in a solvent to prepare a dope, and casting the dope on an endless metal support that moves infinitely. It is performed by a step of drying the cast dope as a web, a step of peeling from the metal support, a step of stretching or maintaining the width, a step of further drying, and a step of winding up the finished film.

  The process for preparing the dope will be described. The concentration of cellulose ester in the dope is preferably higher because the drying load after casting on the metal support can be reduced. However, if the concentration of cellulose ester is too high, the load during filtration increases and the filtration accuracy is poor. Become. As a density | concentration which makes these compatible, 10-35 mass% is preferable, More preferably, it is 15-25 mass%.

  The solvent used in the dope may be used alone or in combination of two or more, but it is preferable to use a mixture of a good solvent and a poor solvent of cellulose ester in terms of production efficiency, and there are many good solvents. This is preferable from the viewpoint of the solubility of the cellulose ester.

  The preferable range of the mixing ratio of the good solvent and the poor solvent is 70 to 98% by mass for the good solvent and 2 to 30% by mass for the poor solvent. With a good solvent and a poor solvent, what dissolve | melts the cellulose ester to be used independently is defined as a good solvent, and what poorly swells or does not melt | dissolve is defined as a poor solvent.

  Therefore, depending on the average acetylation degree (acetyl group substitution degree) of the cellulose ester, the good solvent and the poor solvent change. For example, when acetone is used as the solvent, the cellulose ester acetate ester (acetyl group substitution degree 2.4), cellulose Acetate propionate is a good solvent, and cellulose acetate (acetyl group substitution degree 2.8) is a poor solvent.

  Although the good solvent used for this invention is not specifically limited, Organic halogen compounds, such as a methylene chloride, dioxolanes, acetone, methyl acetate, methyl acetoacetate, etc. are mentioned. Particularly preferred is methylene chloride or methyl acetate.

  Moreover, although the poor solvent used for this invention is not specifically limited, For example, methanol, ethanol, n-butanol, cyclohexane, cyclohexanone, etc. are used preferably. Moreover, it is preferable that 0.01-2 mass% of water contains in dope. Moreover, the solvent used for melt | dissolution of a cellulose ester collect | recovers the solvent removed from the film by drying at the film-forming process, and uses this again.

  A general method can be used as a dissolution method of the cellulose ester when preparing the dope described above. When heating and pressurization are combined, it is possible to heat above the boiling point at normal pressure. It is preferable to stir and dissolve while heating at a temperature that is equal to or higher than the boiling point of the solvent at normal pressure and that the solvent does not boil under pressure, in order to prevent the generation of massive undissolved materials called gels and mamaco. Moreover, after mixing a cellulose ester with a poor solvent and making it wet or swell, the method of adding a good solvent and melt | dissolving is also used preferably.

  The pressurization may be performed by a method of injecting an inert gas such as nitrogen gas or a method of increasing the vapor pressure of the solvent by heating. Heating is preferably performed from the outside. For example, a jacket type is preferable because temperature control is easy.

  The heating temperature with the addition of a solvent is preferably higher from the viewpoint of the solubility of the cellulose ester, but if the heating temperature is too high, the required pressure increases and the productivity deteriorates. A preferable heating temperature is 45 to 120 ° C, more preferably 60 to 110 ° C, and still more preferably 70 ° C to 105 ° C. The pressure is 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 filter paper. As the filter medium, it is preferable that the absolute filtration accuracy is small in order to remove insoluble matters and the like, but there is a problem that the filter medium is likely to be clogged if the absolute filtration accuracy is too small. For this reason, a filter medium with an absolute filtration accuracy of 0.008 mm or less is preferable, a filter medium with 0.001 to 0.008 mm is more preferable, and a filter medium with 0.003 to 0.006 mm is still more preferable.

  There are no particular restrictions on the material of the filter medium, and ordinary filter media can be used. However, plastic filter media such as polypropylene and Teflon (registered trademark) and metal filter media such as stainless steel do not drop off fibers. preferable. It is preferable to remove and reduce impurities, particularly bright spot foreign matter, contained in the raw material cellulose ester by filtration.

The bright spot foreign matter was placed in a crossed Nicols state with two polarizing plates, a rolled cellulose ester was placed between them, and light was applied from the side of one polarizing plate, and observed from the side of the other polarizing plate. It is a point (foreign matter) where light from the opposite side sometimes leaks, and the number of bright spots having a diameter of 0.01 mm or more is preferably 200 / cm ² or less. More preferably, it is 100 pieces / cm < ² > or less, More preferably, it is 50 pieces / m < ² > or less, More preferably, it is 0-10 pieces / cm < ² > or less. Further, it is preferable that the number of bright spots of 0.01 mm or less is small.

  The dope can be filtered by a normal method, but the method of filtering while heating at a temperature not lower than the boiling point of the solvent at normal pressure and in a range where the solvent does not boil under pressure is the filtration pressure before and after filtration The increase in the difference (referred to as differential pressure) is small and preferable. A preferred temperature is 45 to 120 ° C, more preferably 45 to 70 ° C, and still more preferably 45 to 55 ° C.

  A smaller filtration pressure is preferred. The filtration pressure is preferably 1.6 MPa or less, more preferably 1.2 MPa or less, and further preferably 1.0 MPa or less.

  Here, the dope casting will be described.

  The metal support in the casting (casting) step preferably has a mirror-finished surface, and a stainless steel belt or a drum whose surface is plated with a casting is preferably used as the metal support. The cast width can be 1 to 4 m. The surface temperature of the metal support in the casting step is −50 ° C. to a temperature lower than the boiling point of the solvent, and a higher temperature is preferable because the web can be dried faster. May deteriorate. A preferable support body temperature is 0-40 degreeC, and 5-30 degreeC is still more preferable.

  Alternatively, it is also a preferable method that the web is gelled by cooling and peeled from the drum in a state containing a large amount of residual solvent.

  The method for controlling the temperature of the metal support is not particularly limited, and there are a method of blowing hot air or cold air, and a method of contacting hot water with the back side of the metal support. It is preferable to use warm water because heat transfer is performed efficiently, so that the time until the temperature of the metal support becomes constant is short. When warm air is used, wind at a temperature higher than the target temperature may be used.

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

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

Residual solvent amount (% by mass) = {(MN) / N} × 100
M is the mass of a sample collected during or after the production of the web or film, and N is the mass after heating M at 115 ° C. for 1 hour.

  In the drying step of the roll cellulose ester, the web is peeled off from the metal support and further dried, and the residual solvent amount is preferably 1% by mass or less, more preferably 0.1% by mass or less. Particularly preferably, it is 0 to 0.01% by mass or less.

  In the film drying process, generally, a roll drying method (a method in which a plurality of rolls arranged on the upper and lower sides are alternately passed through and dried) or a method of drying while transporting the web by a tenter method is adopted.

  In order to produce a cellulose ester film, a tenter method in which the web is stretched in the transport direction (= long direction) where the residual solvent amount of the web immediately after peeling from the metal support is large, and further, both ends of the web are gripped with clips or the like. It is particularly preferable to perform stretching in the width direction.

<Circular polarizer>
The circular polarizer of the present invention has an absorption axis oblique to the longitudinal direction of the roll-shaped polarizing plate, and the angle formed by the slow axis of the first protective film and the absorption axis of the polarizer is 45 ° ± 10 °. By using a polarizer having an oblique absorption axis, the contrast of the four corners of a horizontal electric field type switching mode type large screen or a 3D liquid crystal display device can be improved. In particular, it can be preferably applied to a lateral electric field type switching mode type 3D liquid crystal display device.

  This is estimated as follows. The polarizer has a strong contraction force in the stretching direction of the polarizer and in the direction perpendicular to the stretching depending on the heat when the panel is turned on and the humidity of the usage environment. The shrinkage force to the polarizer increases from the center of the panel bonded to the polarizing plate according to the outside, but when the polarizing plate absorption axis is arranged horizontally or vertically with respect to the liquid crystal panel, it is strongest at the four corners of the liquid crystal screen. Contraction force works. Therefore, polarization unevenness occurs at the four corners of the liquid crystal screen due to deformation (extension / contraction) of the polarizing plate. In the case of an IPS panel, the contraction force acting on the protective film on the liquid crystal panel side of the polarizing plate develops a phase difference due to the photoelasticity of the protective film, and the contrast and color misregistration performance at the four corners decrease.

  In particular, in the case of a 3D panel, due to the λ / 4 distortion that constitutes a circularly polarizing plate, the circularly polarized light that should originally be obtained becomes elliptically polarized light, resulting in a significant reduction in contrast and 3D stereoscopic effect.

  In this configuration in which the polarizer has an absorption axis that is oblique with respect to the longitudinal direction of the roll-shaped polarizing plate, it is possible to easily arrange the absorption axis in an oblique direction with respect to the liquid crystal panel. In addition, it is possible to eliminate polarization unevenness and improve contrast and 3D stereoscopic effect.

  The polarizer of the present invention is preferably used as a polarizing plate provided with a polarizer in the form of a support.

  A known λ / 4 plate (retardation film) can be used for the circular polarizer.

  The λ / 4 plate used in the present invention means a plate having a function of converting linearly polarized light having a specific wavelength into circularly polarized light (or circularly polarized light into linearly polarized light). The λ / 4 plate has an in-plane retardation value Ro of about ¼ for a predetermined wavelength of light (usually in the visible light region).

  The λ / 4 plate according to the present invention is a retardation plate (film) having a retardation of approximately ¼ of the wavelength in the visible light wavelength range in order to obtain almost perfect circularly polarized light in the visible light wavelength range. It is preferable that Ro, Rt, and θ can be measured using an automatic birefringence meter. Using an automatic birefringence meter KOBRA-21ADH (manufactured by Oji Scientific Instruments), Ro is calculated by birefringence measurement at each wavelength in an environment of 23 ° C. and 55% RH. θ represents an orientation angle, and the longitudinal direction of the film was set as a reference (0 °).

  A circularly polarizing plate is obtained by laminating so that the angle between the slow axis of the λ / 4 plate and the transmission axis of the polarizer described later is substantially 45 °. “Substantially 45 °” means 35 to 55 °. The angle between the slow axis in the plane of the λ / 4 plate and the transmission axis of the polarizer is preferably 41 to 49 °, more preferably 42 to 48 °, and 43 to 47 °. Is more preferable, and it is most preferable that it is 44-46 degrees.

  The Nz coefficient of at least one of the λ / 4 plates is preferably in the range of 1.1 to 4.0, more preferably in the range of 1.3 to 3.5, and 1.5 to Most preferred is a range of 2.5.

  In general, a method for producing a λ / 4 polarizing plate is a method in which a retardation film is stretched in an oblique direction and bonded with a polarizer stretched in a longitudinal direction or a width direction, or stretched in a longitudinal direction or a width direction. It is produced by a method in which a retardation film is bonded to a polarizer in a sheet form. The former has a drawback that it is easy to break at the time of stretching the film, and it is very difficult to obtain a uniform film, and the contrast and display unevenness are remarkably inferior. there were.

  In the present invention, for example, as described in JP2011-22223A, a lyotropic liquid crystal compound is aligned by applying the lyotropic liquid crystal compound onto an alignment-treated plastic substrate (also referred to as a support film). A method of obtaining an alignment film having a polarizer having an absorption axis oblique to the alignment direction of the support film is preferable. This method is advantageous in that a uniform and thin film can be obtained. It is preferable that the absorption axis is inclined 45 ° ± 10 ° with respect to the longitudinal direction.

<Polarizer production method>
A method for producing a polarizing plate by applying a lyotropic liquid crystal compound on an orientation-treated support film to obtain a polarizer having an absorption axis oblique to the orientation direction of the support film will be described below with reference to FIG. .

  FIG. 1 is a schematic diagram of an example of a roll-shaped polarizing plate in which a polarizer has an absorption axis oblique to the longitudinal direction of the polarizing plate.

  This is a method for producing a roll-shaped polarizing plate 10 in which an alignment film 18 having a width direction 19 of the support film 11 and an absorption axis 17 in a different direction is laminated on the support film 11. This manufacturing method includes step A and step B.

  In step A, the surface of the support film 11 is subjected to orientation treatment in two directions. The two directions are the first alignment processing direction 12 and the second alignment processing direction 13.

  In step B, a solution containing the lyotropic liquid crystal compound 14 is applied to the surface of the support film 11. The lyotropic liquid crystal compound 14 forms columnar aggregates 15 in the solution. The columnar aggregate 15 is oriented in the vector sum direction (orientation direction 16) of the first orientation treatment direction 12 and the second orientation treatment direction 13.

  The manufacturing method of the present invention may include other steps in addition to steps A and B. As such a process, for example, after the process B, there is a process of drying the alignment layer (alignment film 18) of the lyotropic liquid crystal compound 14.

[Step A]
In step A, the surface of the support film 11 is subjected to orientation treatment in two directions. The two directions are the first alignment processing direction 12 and the second alignment processing direction 13.

  The support film 11 supports the alignment film 18 from one side. The material of the plastic substrate (support film) 11 is not particularly limited, and examples thereof include polyester resins, cellulose resins, cycloolefin resins, and acrylic resins.

  The support film 11 may be a single layer film or a multilayer film in which a polymer film such as polyimide or polyvinyl alcohol is coated on a single layer film. The total thickness of the support film 11 is preferably 10 μm to 200 μm.

  Examples of the alignment treatment include rubbing treatment, oblique vapor deposition treatment, and plasma treatment. These alignment treatments are described in, for example, Shoichi Matsumoto and Ryoko Kakuda, “Basics and Applications of Liquid Crystals” (Industry Research Committee, published in 1991).

As a method for performing the alignment treatment in two different directions in the plane, for example, there are the following methods.
(A) Rubbing is performed in two different directions.
(A) After the oblique deposition process, a rubbing process is performed in a different direction.
(C) Two rubbing films that have been rubbed in different directions are overlapped so that the rubbed surfaces face each other, and the orientation regulating force of the other rubbing film is transferred to one rubbing film. .

  When the two-direction alignment treatment applied to the support film 11 is the first alignment treatment (direction 12) and the second alignment treatment (direction 13), the first alignment treatment 12 and the second alignment treatment 13 are performed. The angle θ is preferably 30 ° to 150 °.

[Step B]
In step B, the alignment film 18 is formed by applying a solution containing the lyotropic liquid crystal compound 14 to the alignment treatment surface of the support film 11 obtained in step A. The lyotropic liquid crystal compound 14 forms columnar aggregates 15 in the solution. A large number of columnar aggregates 15 are formed into a thin film to form the alignment film 18. The laminated body provided with the support film 11 and the alignment film 18 is the roll-shaped polarizing plate 10 of the present invention.

  In the present invention, the “lyotropic liquid crystal compound” is a liquid crystal compound that dissolves in a solvent to form a liquid crystal compound solution and causes a phase change from the isotropic phase to the liquid crystal phase (or vice versa) due to a concentration change in the solution. .

  The lyotropic liquid crystal compound solution can be aligned in one direction by applying it to the alignment-treated surface in an isotropic phase state or a liquid crystal phase state.

  The lyotropic liquid crystal compound forms a columnar aggregate 15 by stacking with the molecular long axis (absorption axis 17) facing sideways. The length L1 of the columnar aggregate 15 obtained from X-ray diffraction is preferably 4 nm to 9 nm.

  The lyotropic liquid crystal compound 14 is not particularly limited as long as it exhibits the above properties. For example, azo compounds, anthraquinone compounds, perylene compounds, quinophthalone compounds, naphthoquinone compounds, and merocyanine compounds are used. .

  As the lyotropic liquid crystal compound 14 used in the present invention, an azo compound represented by the general formula (14) is suitable. The azo compound represented by the general formula (14) exhibits stable liquid crystallinity in a solution and is excellent in orientation.

In general formula (14), R represents a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, an acetyl group, a benzoyl group, or a phenyl group which may have a substituent. M represents a counter ion, preferably a hydrogen atom, an alkali metal atom, or an alkaline earth metal atom. X represents a hydrogen atom, a halogen atom, a nitro group, a cyano group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or an —SO ₃ M group.

  The azo compound represented by the general formula (14) is obtained by, for example, subjecting an aniline derivative and a naphthalenesulfonic acid derivative to diazotization and coupling reaction by a conventional method to form a monoazo compound, and further diazotizing it to produce aminonaphthol disulfone. It can be obtained by a coupling reaction with an acid derivative.

  The solution used contains the lyotropic liquid crystal compound 14 and a solvent that dissolves it. The concentration of the lyotropic liquid crystal compound 14 is preferably 1% by mass to 15% by mass with respect to the total mass of the solution.

  An arbitrary coater is used for applying the solution. The coater is, for example, a coater having a tension web die, a slot die, a wire bar, or a curtain roll.

  The alignment film 18 obtained by the process B includes the lyotropic liquid crystal compound 14, and the columnar aggregate 15 formed by the lyotropic liquid crystal compound 14 is aligned in one direction.

  Such an alignment film 18 exhibits absorption dichroism in the visible light region (wavelength 380 nm to 780 nm). The thickness of the alignment film 18 is preferably 0.1 μm to 5 μm.

  The alignment film 18 is preferably dried so that the solvent content is 50% by mass or less. The drying means in this case is natural drying, reduced pressure drying, heat drying or the like.

[Rolled polarizing plate]
The roll-shaped polarizing plate 10 obtained by the production method of the present invention includes a support film 11 and an alignment film 18 having an absorption axis 17 in an oblique direction in the width direction 19 of the support film 11. The total thickness of the roll-shaped polarizing plate 10 is preferably more than 10 μm and 250 μm or less.

  In the present invention, the support film can also serve as the second protective film. Such a structure is preferable because the number of layers can be reduced and the contrast is improved.

  This can be achieved by reducing the number of layers, and the optical loss due to the bonding interface can be reduced to improve the contrast. Furthermore, there is no peeling or wrinkle at the interface due to environmental fluctuations such as thermal humidity of the panel, which is preferable in terms of durability of the liquid crystal panel.

<Example of polarizer production>
[Synthesis example]
4-Nitroaniline and 8-amino-2-naphthalenesulfonic acid were subjected to diazotization and coupling reaction according to a conventional method to obtain a monoazo compound. "Regular method" is based on Yutaka Hosoda, "Theoretical Manufacturing, Dye Chemistry 5th Edition," July 15, 1968, published by Gihodo, pages 135-152

  This monoazo compound is similarly diazotized by a conventional method, and further subjected to a coupling reaction with 1-amino-8-naphthol-2,4-disulfonic acid lithium salt to obtain a crude product containing the azo compound of the structural formula (2) Got. This was salted out with lithium chloride to obtain an azo compound of the structural formula (2).

  The azo compound of the structural formula (2) was dissolved in ion exchange water to prepare a 20% by mass aqueous solution. In this aqueous solution, the azo compound forms a columnar aggregate and exhibits a nematic liquid crystal phase at room temperature (23 ° C.).

(Relationship with IPS liquid crystal cell)
In the IPS liquid crystal display device, the liquid crystal layer of the liquid crystal panel is homogeneously aligned in parallel with the substrate surface in the initial state, and the director of the liquid crystal layer on the plane parallel to the substrate is parallel to the electrode wiring direction when no voltage is applied. When the voltage is applied, the direction of the director of the liquid crystal layer shifts to the direction perpendicular to the electrode wiring direction when the voltage is applied, and the direction of the director of the liquid crystal layer is the direction of the director when no voltage is applied. Compared to the 45 ° electrode wiring direction, the liquid crystal layer when the voltage is applied rotates the polarization azimuth by 90 ° like a half-wave plate, and the transmission axis of the emission side light plate and the azimuth of the polarization The corners match and the display is white.

  In general, the thickness of the liquid crystal layer is constant, but since it is driven by a lateral electric field, it is considered that a slight unevenness in the thickness of the liquid crystal layer can increase the response speed to switching. Even if the thickness of the layer is not constant, the effect can be maximized.

  In this invention, there is little influence with respect to the change of the thickness of a liquid crystal layer. The thickness of the liquid crystal layer capable of greatly exerting the effect in the present invention is 2 to 6 μm, and preferably 3 to 5.5 μm.

  The liquid crystal display device of the present invention is used for a large liquid crystal television. As a screen size, it can be used for 17 or more types, preferably 26 to 100 types.

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

(3D liquid crystal display device)
The 3D (stereoscopic) liquid crystal display device of the present invention is a lateral electric field type switching mode liquid crystal display device composed of an IPS liquid crystal cell and two polarizing plates sandwiching the IPS liquid crystal cell. The roll-shaped polarizing plate is arranged and used so that the second protective film is on the electrode side. The display device is provided with a first protective film, a polarizer, and a second protective film in this order from the viewing side. The 3D glasses are provided with a polarizer, a liquid crystal cell, and a λ / 4 plate, and a stereoscopic image can be observed through the 3D glasses.

  This will be described below with reference to the drawings.

  FIG. 2 is an example of a conceptual diagram of 3D liquid crystal glasses. This is a method of wearing 3D glasses (G) and viewing an image on a liquid crystal display. As shown in FIG. 2, the 3D liquid crystal glasses (G) are provided with liquid crystal shutters (S1) and (S2) for the left and right eyes, and a control circuit CC for controlling the liquid crystal shutters (S1) and (S2) is provided. It is connected.

  As in the 3D display device shown in FIG. 3, the image displayed on the liquid crystal display (LCD) has a left-eye image (LI) and a right-eye image (RI) assigned to two fields, respectively. Yes, these are alternately displayed at high speed in time series. The light emitted from the liquid crystal display (LCD) of the present invention is linearly polarized light and circularly polarized light passing through the λ / 4 plate. Further, the left and right switching of the 3D glasses is performed in synchronization with the switching of the left eye image (LI) and the right eye image (RI).

  By providing the 3D glasses with the λ / 4 plate, it is possible to eliminate a decrease in luminance and a change in color when the head is tilted. It is preferable that λ / 4 is used for the surface on the viewing side of the liquid crystal display and the surface on the side far from the eyes of the stereoscopic image viewing glasses, respectively.

  Specifically, the 3D glasses are preferably a cellulose ester, a polarizer, a cellulose ester, a liquid crystal cell, and a λ / 4 plate from the viewing side.

  The liquid crystal display preferably has a configuration in which the backlight, the lower polarizing plate, the IPS liquid crystal panel, and the polarizing plate of the present invention are used from the side far from the visual recognition.

  In the lower polarizing plate, the polarizer of the present invention is located on the opposite side through the IPS liquid crystal panel, and the absorption axis is 90 ° with the polarizer of the present invention.

  Known polarizers and backlights for the lower polarizing plate are used, but the oblique polarizers according to the present invention can also be used for the lower polarizer.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

Example 1
(Preparation of polarizing plate 101)
(Preparation of the first protective film 1)
<Fine particle dispersion 1>
Fine particles (Aerosil R972V manufactured by Nippon Aerosil Co., Ltd.) 11 parts by weight Ethanol 89 parts by weight The above was stirred and mixed with a dissolver for 50 minutes, and then dispersed with Manton Gorin.

<Fine particle addition liquid 1>
The fine particle dispersion 1 was slowly added to the dissolution tank containing methylene chloride with sufficient stirring. Further, the particles were dispersed by an attritor so that the secondary particles had a predetermined particle size. This was filtered through Finemet NF manufactured by Nippon Seisen Co., Ltd. to prepare a fine particle additive solution 1.

Methylene chloride 99 parts by mass Fine particle dispersion 1 5 parts by mass A main dope solution having the following composition was prepared. First, methylene chloride and ethanol were added to the pressure dissolution tank. Cellulose acetate was added to a pressurized dissolution tank containing a solvent while stirring. This is completely dissolved with heating and stirring. This was designated as Azumi Filter Paper No. The main dope solution was prepared by filtration using 244.

<Composition of main dope solution>
Methylene chloride 340 parts by mass Ethanol 64 parts by mass Cellulose acetate with an acetyl group substitution degree of 2.45 (Mn; 53000)
100 parts by mass Sugar ester compound (Exemplary compound; Compound 3) 10.0 parts by mass Polyester (Ester-based exemplary compound; B-15) 2.5 parts by mass Ultraviolet absorber (Tinuvin 928 (manufactured by BASF Japan Ltd.)) 2 .3 parts by mass Particulate additive solution 1 1 part by mass The above was put into a closed container and dissolved while stirring to prepare a dope solution. Next, an endless belt casting apparatus was used to uniformly cast the dope solution on a stainless steel belt support at a temperature of 33 ° C. and a width of 2000 mm. The temperature of the stainless steel belt was controlled at 30 ° C.

  On the stainless steel belt support, the solvent was evaporated until the residual solvent amount in the cast (cast) film was 75%, and then peeled off from the stainless steel belt support with a peeling tension of 130 N / m.

  After peeling, using the apparatus described in Example 1 of JP-A-2009-214441 (stretching machine A: FIG. 11), the slow axis is 45 ° with the film width direction at a temperature of 170 ° C. and a magnification of 1.35 times. As was done, the film was stretched in an oblique direction.

  Next, drying was terminated while the drying zone was conveyed by a number of rolls. The drying temperature was 130 ° C. and the transport tension was 100 N / m.

  As described above, the first protective film having a width of 1500 mm, a knurling having a width of 1 cm and a height of 8 μm, a dry film thickness of 80 μm, an orientation angle θ = 45 °, Ro = 138 nm, and Rt = 160 nm. 1 was obtained.

(Production of second protective film)
A main dope solution having the following composition was prepared. First, methylene chloride and ethanol were added to the pressure dissolution tank. Cellulose acetate was added to a pressurized dissolution tank containing a solvent while stirring. This was heated to 70 ° C., and while stirring, cellulose triacetate (TAC) was completely dissolved to obtain a dope. The time required for dissolution was 4 hours. This was designated as Azumi Filter Paper No. The main dope solution was prepared by filtration using 244.

(Main dope composition)
Cellulose acetate with an acetyl group substitution degree of 2.87 (Mn; 136000)
85 parts by mass ・ 2- (2′-hydroxy-3 ′, 5′-di-t-butylphenyl) bezotriazole
1.5 parts by mass-Methyl methacrylate-2-hydroxyethyl acrylate copolymer (80/20 (mass ratio)) Mw; 8000 8 parts by mass-Methyl acrylate polymer (*) Mw; 1000 5 parts by mass-Methylene chloride 475 Part by mass-50 parts by mass of ethanol-2 parts by mass of fine particle additive liquid (*) A methyl acrylate monomer was polymerized by the polymerization method described in Example 3 of Japanese Patent Application Laid-Open No. 2000-128911 to obtain polymers of Mw1000 and Mn700. This reaction product had a hydroxyl value (hydroxy group value) (OHV; mgKOH / g) of 50.

  Using a belt casting apparatus, the film was uniformly cast on a stainless steel band support having a dope temperature of 35 ° C. and a temperature of 22 ° C. The temperature of the stainless steel band support was 20 ° C.

  Then, after making it dry to the range which can be peeled, dope was peeled from the stainless steel band support body. The residual solvent amount of the dope at this time was 25% by mass. The time required from casting the dope to peeling was 3 minutes. Peel from the stainless steel band support with a tension of 10 kg / m, stretch 2% in the width direction with a tenter at 140 ° C, and then finish drying in a drying zone at 120 ° C and 135 ° C while transporting with many rolls. I let you. The winding tension was an initial tension of 10 kg / m and a final winding tension of 8 kg / m.

  As described above, a second protective film having a dry film thickness of 40 μm, Ro = 0.2 nm, and Rt = 1 nm having a width of 1500 mm, a width of 1 cm at the end, and a height of 5 μm was obtained.

  In addition, each Ro, Rt, and orientation angle | corner (theta) of the 1st protective film 1 and the 2nd protective film were measured using automatic birefringence meter KOBRA-21ADH (Oji Scientific Instruments Co., Ltd. product). Ro was calculated by measuring the birefringence at each wavelength in an environment of 23 ° C. and 55% RH. θ is based on the longitudinal direction of the film (0 °).

  The number average molecular weight (Mn) of cellulose acetate was measured by the method described above.

(Creating a polarizer)
A 75 μm thick polyvinyl alcohol film was swollen with water at 35 ° C. The obtained film was immersed in an aqueous solution consisting of 0.075 g of iodine, 5 g of potassium iodide and 100 g of water for 60 seconds; and further immersed in an aqueous solution of 45 ° C. consisting of 3 g of potassium iodide, 7.5 g of boric acid and 100 g of water. did. The obtained film was uniaxially stretched under the conditions of a stretching temperature of 55 ° C. and a stretching ratio of 6 times. The uniaxially stretched film was washed with water and dried to obtain a polarizer having a thickness of 20 μm.

  Then, according to the following processes 1-5, the polarizer, the 1st protective film 1, and the 2nd protective film were bonded together on the back surface side, and the polarizing plate was produced.

  Step 1: Soaked in a 2 mol / L sodium hydroxide solution at 60 ° C. for 90 seconds, then washed with water and dried to obtain a first protective film 1 saponified on the side to be bonded to the polarizer.

  Process 2: The said polarizer was immersed in the polyvinyl alcohol adhesive tank of 2 mass% of solid content for 1-2 seconds.

  Step 3: Excess adhesive adhered to the polarizer in Step 2 was lightly wiped off and placed on the first protective film 1 treated in Step 1.

Step 4: the first protective film 1 and the polarizer laminated in step 3, the pressure 20-30 N / cm ² the second protective film, the transport speed was pasted at approximately 2m / min.

  Step 5: The sample prepared in Step 4 was dried in a dryer at 80 ° C. for 2 minutes to prepare a roll-shaped polarizing plate 101.

  In the obtained polarizing plate 101, the angle formed by the slow axis of the first protective film 1 and the absorption axis of the polarizer was 45 °.

(Creation of polarizing plate 102)
In the production of the first protective film 1 of the polarizing plate 101, after peeling, the both ends of the web are gripped by a tenter and stretched so that the stretching ratio in the width (TD) direction is 1.35 times. Is maintained for a few seconds, relaxes the tension in the width direction, releases the width holding, and further transports in the third drying zone set at 125 ° C. for 30 minutes for drying. The 1st protective film 2 was created by the method. The residual solvent at the start of stretching was 30%.

  As described above, a first protective film 2 having a dry film thickness of 66 μm, θ = 90 °, Ro = 136 nm, and Rt = 228 nm was obtained.

(Creating a polarizer)
In the production of the polarizer of the polarizing plate 101, the apparatus described in Example 1 of JP-A-2009-214441 (stretching machine A: FIG. 11) is used, and the absorption axis is a film at a stretching temperature of 55 ° C. and a stretching ratio of 5 times. A polyvinyl alcohol film polarizer was obtained in the same manner except that the film was stretched in an oblique direction so as to form 45 ° with the width direction.

  Next, in accordance with Steps 1 to 5 for producing the polarizing plate 101, the polarizer and the first protective film 2 and the second protective film were bonded to the back surface side to produce the polarizing plate 102.

  In the obtained polarizing plate 102, the angle formed by the slow axis of the first protective film 2 and the absorption axis of the polarizer was 45 °.

(Creation of polarizing plate 103)
(Creating a polarizer)
A support film is obtained by rubbing the surface of a cycloolefin resin film (Zeonor manufactured by Optes Co., Ltd.) having a thickness of 100 μm in two directions with a cotton buff cloth (YA-25-C manufactured by Yoshikawa Chemical Co., Ltd.). It was. The two directions are 125 ° and 145 ° counterclockwise with respect to the width direction of the film.

  An aqueous solution (concentration: 7% by mass) containing a lyotropic liquid crystal compound, which is an azo compound of the structural formula (2), is applied to the treated surface of the orientation-treated support film, oriented, dried, and oriented with a thickness of 0.5 μm. A membrane was prepared. The angle between the absorption axis of the polarizer of the obtained alignment film and the film width direction was 45 °.

  Next, in accordance with Steps 1 to 5 for producing the polarizing plate 101, the polarizer, the first protective film 2, and the second protective film on the back side were bonded together to produce the polarizing plate 103.

  In the obtained polarizing plate 103, the angle formed by the slow axis of the first protective film 2 and the absorption axis of the polarizer was 45 °.

(Polarizing plate 104)
In the production of the polarizing plate 103, a polarizing plate 104 was obtained in the same manner except that a polarizer was produced using a second protective film instead of the cycloolefin-based resin film as a support film for the polarizer.

(Polarizing plate 105-109)
In making the polarizing plate 104, the first protective film was stretched in the width (TD) direction so as to have the retardation and film thickness described in Table 1, and by changing the angle of the absorption axis of the polarizer. As shown in the table, polarizing plates 105 to 109 were prepared in the same manner except that the angle formed by the slow axis of the first protective film and the absorption axis of the polarizer was changed.

(Polarizing plate 110)
(Production of polarizer)
On the second protective film as a support film, an alignment film coating solution having the following composition was applied at a coating amount of 28 ml / m ² with a # 16 wire bar coater. A polyvinyl alcohol layer was formed by drying with warm air of 60 ° C. for 60 seconds and further with warm air of 90 ° C. for 150 seconds.

(Orientation film coating solution composition)
The following modified polyvinyl alcohol 10 parts by weight Water 371 parts by weight Methanol 119 parts by weight Glutaraldehyde (crosslinking agent) 0.5 parts by weight

  The surface of the formed polyvinyl alcohol layer was rubbed in two directions with a cotton buff cloth (Ya-25-C, manufactured by Yoshikawa Chemical Co., Ltd.) and rubbed to obtain a support film with an alignment film. The two directions are 35 ° and 55 ° counterclockwise with respect to the width direction of the film.

  An aqueous solution (concentration: 7% by mass) containing a lyotropic liquid crystal compound, which is an azo compound of the structural formula (2), is applied to the treated surface of the orientation-treated support film, oriented, dried, and oriented with a thickness of 0.5 μm. A membrane was prepared. The angle between the absorption axis of the polarizer of the obtained alignment film and the film width direction was 45 °.

  Next, in accordance with Steps 1 to 5 for producing the polarizing plate 101, the polarizer, the first protective film 2, and the second protective film were bonded to the back surface side to produce the polarizing plate 110.

  In the obtained polarizing plate 110, the angle formed by the slow axis of the first protective film 2 and the absorption axis of the polarizer was 45 °.

(Polarizing plate durability evaluation)
The obtained polarizing plates 101 to 110 are cut into a 42-inch liquid crystal panel size (930 mm * 520 mm), left in a high-temperature and high-humidity atmosphere at 60 ° C. and 90% RH for 300 hours, and then the diagonal center point (ρ0) The wet heat durability was evaluated by classifying the degree of polarization degree variation at the 75% point (ρ75) from the center on the diagonal line as a percentage difference of the degree of polarization C as follows. A smaller value is preferable because there is less unevenness in the image.

  In addition, polarization degree (rho) was computed with the automatic polarizing film measuring apparatus VAP-7070 (made by JASCO Corporation) and a special program.

(Polarity variation ((ρ75)-(ρ0)))
◎: Less than 1% ○: 1% or more and less than 2% △: 2% or more and less than 5% ×: 5% or more In the table, the number of the roll-shaped polarizing plate is abbreviated as polarizing plate No, the orientation angle θ is θ, and the polyvinyl alcohol film is abbreviated as PVA. In the table, it is shown that MD is produced by stretching the polarizer in the longitudinal direction and obliquely in the oblique direction.

  As shown in Table 1, the roll-shaped circularly polarizing plate of the present invention is preferable because the variation in the degree of polarization after the wet heat durability test is small.

Example 2
(Creation of liquid crystal display device):
Take out the liquid crystal panel from the liquid crystal display device [Regza 47ZG2 manufactured by Toshiba Corp.] including the liquid crystal cell of the horizontal electric field type switching mode type (IPS mode type), remove the polarizing plate arranged above and below the liquid crystal cell, The glass surface (front and back) of the liquid crystal cell was washed.

  Subsequently, in the polarizing plate of the present invention, the slow axis of the first protective film is parallel to the long side of the liquid crystal cell in the upper (viewing side) polarizing plate so that the second protective film is on the liquid crystal panel side. (0 ± 0.2 degrees) and the lower (backlight side) polarizing plate is placed on both sides of the liquid crystal cell so as to be parallel (0 ± 0.2 degrees) with the short side of the liquid crystal cell. It stuck using the acrylic adhesive (thickness 20 micrometers).

  By the above method, liquid crystal display devices 201 to 210 were obtained.

(Measurement method of contrast ratio of liquid crystal display device)
The contrast ratio was measured in a dark room at 23 ° C. using the following method, liquid crystal cell, and measuring apparatus.

  A white image and a black image were displayed on the liquid crystal display device, and the Y value of the XYZ display system in the azimuth angle 45 ° direction and polar angle 60 ° direction of the display screen was measured by a product name “EZ Contrast 160D” manufactured by ELDIM. Then, the contrast ratio “YW / YB” in the oblique direction was calculated from the Y value (YW) in the white image and the Y value (YB) in the black image. An azimuth angle of 45 ° represents an azimuth rotated 45 ° counterclockwise when the long side of the panel is 0 °, and a polar angle of 60 ° is when the front direction of the display screen is 0 °. Represents a direction inclined at an angle of 60 °. The measurement was performed in a dark room at a temperature of 23 ° C. and a humidity of 55%. Higher values are preferable because of higher contrast.

(3D stereoscopic evaluation)
A 3D image was played on the created display device, and the 3D stereoscopic effect was sensorially evaluated by 10 researchers using the attached “regza 3D glasses” of the active shutter system.

(3D stereoscopic evaluation criteria)
3 points: 3D effect is very high 2 points: 3D effect is high 1 point: 3D effect is weak 0 points: 3D effect is not felt (image unevenness evaluation)
The liquid crystal display is thermo-treated for 1500 hours at 60 ° C and 90% RH, and after conditioning for 20 hours at 25 ° C and 60% RH, a 3D image is played, the stereoscopic effect at the center of the diagonal, and the center on the diagonal The sensory evaluation by 10 researchers was performed on the difference in stereoscopic effect at the 75% point (edge).

  In the table, 3D stereoscopic effect and image unevenness indicate the average score of all evaluators.

(Image unevenness evaluation criteria)
3 points: There is no difference between the central part and the end part 2 points: There is almost no difference between the central part and the end part 1 point: The difference between the central part and the end part is felt 0 point: The difference between the central part and the end part is felt Very big

  As shown in Table 2, the lateral electric field type switching mode type (IPS mode type) liquid crystal display device using the rolled circularly polarizing plate of the present invention has a high 3D stereoscopic effect, high contrast, and after wet heat durability. It can be seen that the variation in the center and end of the three-dimensional effect is small and preferable.

DESCRIPTION OF SYMBOLS 10 Roll-shaped polarizing plate 11 Support film 12 1st orientation processing direction 13 2nd orientation processing direction 14 Lyotropic liquid crystal compound 15 Column-like aggregate 16 Orientation direction 17 Absorption axis 18 Orientation film 19 Width direction 20 Longitudinal direction G 3D liquid crystal glasses S1 liquid crystal shutter S2 liquid crystal shutter LI image for left eye RI image for right eye

Claims (4)

A roll-shaped circularly polarizing plate for a transverse electric field type switching mode liquid crystal display device, in which a first protective film, a polarizer, and a second protective film are laminated in this order, wherein the polarizer is the transverse electric field type switching mode type It has an absorption axis that is oblique with respect to the longitudinal direction of the roll-shaped circularly polarizing plate for a liquid crystal display device, and the retardation value Ro in the in-plane direction of the first protective film is a temperature of 23 ° C. and a relative humidity of 55% RH. In the measurement at an optical wavelength of 590 nm under the environment, the angle that the slow axis of the first protective film satisfies the following general formula (i) and the absorption axis of the polarizer is 45 ° ± 10 °. A roll-shaped circularly polarizing plate for a horizontal electric field type switching mode type liquid crystal display device characterized by the above.
General formula (i) 80 ≦ Ro ≦ 200
(Wherein, a _{Ro = (n x -n y)} × d, n x is a refractive index in a slow axis direction in a plane of the film, n _y is a refractive in a direction perpendicular to the slow axis in the film plane (Where d represents the thickness of the film (nm))   The polarizer has an alignment film in which a lyotropic liquid crystal compound is aligned, the alignment film is aligned on a plastic substrate, and the absorption axis is inclined 45 ° ± 10 ° with respect to the longitudinal direction. A rolled circularly polarizing plate for a transverse electric field type switching mode type liquid crystal display device according to claim 1.   2. The lateral electric field type switching mode liquid crystal according to claim 1, wherein the polarizer is obtained by performing an alignment treatment on the second protective film and having an absorption axis oblique to the longitudinal direction. Roll-type circularly polarizing plate for display devices.   A lateral electric field type switching mode type 3D liquid crystal display device comprising a liquid crystal cell and two polarizing plates sandwiching the liquid crystal cell, wherein the lateral electric field according to any one of claims 1 to 3 is provided on a viewing side of the liquid crystal cell. A lateral electric field type switching mode type 3D liquid crystal display device, characterized in that a roll-shaped circularly polarizing plate for a flat type switching mode type liquid crystal display device is arranged so that the second protective film is on the electrode side.

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