JP2010026295A - Retardation film, polarizing plate and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a retardation film having an optical anisotropic layer comprising a liquid crystal. <P>SOLUTION: The retardation film includes: a cellulose ester film; an optical anisotropic layer provided on one surface thereon, wherein rod-like liquid crystal molecules are vertically aligned and fixed; and a back surface layer provided on the other surface thereon. In the retardation film: the cellulose ester film satisfies both of the following conditions (A1) and (A2); the solvent content is ≤0.01 mass%; and the film has an elastic modulus CE1 of 1.5 to 2.5 kN/mm<SP>2</SP>in a film forming direction and an elastic modulus CE2 of 1.8 to 3.5 kN/mm<SP>2</SP>in a transverse direction at 23°C and 55% RH. The elastic modulus BC in at least one layer of the back surface layer is (elastic modulus CE1+elastic modulus CE2)/2<elastic modulus BC. The conditions are: (A1) 2.0≤X+Y≤3.0; and (A2) 0.1≤Y≤2.5; wherein X represents a substitution degree of acetyl groups in the cellulose ester; and Y represents a substitution degree of propionyl groups or butyryl groups. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a retardation film having an optically anisotropic layer made of liquid crystal, a polarizing plate using the retardation film, and a liquid crystal display device.

  As a liquid crystal display device, a liquid crystal display device using a so-called in-plane switching (IPS) mode in which a lateral electric field excellent in viewing angle characteristics is applied to the liquid crystal, or a liquid crystal having a negative dielectric anisotropy is vertically aligned. A vertical alignment (VA) mode in which alignment is divided by protrusions and slit electrodes formed in the panel has been proposed and put into practical use.

  In recent years, these panels have been developed not only for monitor applications but also for TV applications, and screen brightness has been greatly improved accordingly. For this reason, a slight light leakage in the diagonally oblique incident direction during black display, which has not been considered as a problem in these operation modes, has become apparent as a cause of a decrease in display quality.

  Many of the proposed methods for improving the viewing angle of the color tone and the black display are based on the birefringence anisotropy of the liquid crystal in the liquid crystal cell by using an optical compensation sheet such as a retardation film. Since this is an improved system, there is a problem in that light leakage based on the deviation from the orthogonal crossing angle of the polarization axes when the orthogonal polarizing plate is viewed obliquely cannot be sufficiently solved.

  Therefore, in Patent Document 1, a retardation layer formed by vertically aligning with an optical compensation sheet is provided on a support as an optically anisotropic layer, and by using an additive in the layer, not only a viewing angle but also a retardation is provided. Techniques have also been proposed for improving screen unevenness due to unevenness.

  In patent document 2, the technique which prescribed | regulated the elasticity modulus of the cellulose acylate film used as the support body for providing an anisotropic layer is proposed.

However, these techniques are not sufficient to cope with the environmental variation of the support for providing the optically anisotropic layer, particularly the unevenness of the screen caused by the influence of the heat from the backlight, and the liquid crystal display device. The enlargement of the screen finally revealed uneven alignment of the liquid crystal layer, which is an optically anisotropic layer.
JP 2007-45993 A JP 2007-2216 A

  An object of the present invention is to provide a retardation film that is durable to environmental changes and has little alignment unevenness in a liquid crystal layer, a polarizing plate using the retardation film, and a liquid crystal display device.

The above object of the present invention is achieved by the following configurations.
1. In a retardation film having a cellulose ester film, an optically anisotropic layer in which a rod-like liquid crystal is vertically aligned on one surface thereof and the orientation is fixed, and a back layer on the other surface, the cellulose ester film is represented by the following formula: (A1) and (A2) are satisfied at the same time, the solvent content is 0.01% by mass or less, and the elastic modulus CE1 in the film forming direction at 23 ° C. and 55% RH is 1.5 to 2.5 kN / mm ² , The elastic modulus CE2 in the width direction is 1.8 to 3.5 kN / mm ² , and the elastic modulus BC of at least one layer of the back layer is (elastic modulus CE1 + elastic modulus CE2) / 2 <elastic modulus BC. A retardation film characterized by that.

Formula (A1) 2.0 ≦ X + Y ≦ 3.0
Formula (A2) 0.1 ≦ Y ≦ 2.5
(In the formula, X represents the degree of substitution of the acetyl group of the cellulose ester, and Y represents the degree of substitution of the propionyl group or butyryl group.)
2. The retardation film is selected from an acrylic polymer and an ester compound in which at least one of a pyranose structure or furanose structure is 1 to 12 and all or part of the OH groups of the structure are esterified. 2. The retardation film as described in 1 above, which is a cellulose ester film containing at least one of the above.
3. A polarizing plate comprising a polarizer and two polarizing plate protective films sandwiching the polarizer, wherein at least one of the polarizing plate protective films is the retardation film described in 1 or 2 above.
4). A liquid crystal display device comprising the retardation film according to 1 or 2 above.

  According to the present invention, it is possible to obtain a retardation film having a small alignment unevenness of a liquid crystal layer which is durable to environmental changes, a polarizing plate and a liquid crystal display device using the retardation film.

Hereinafter, the best mode for carrying out the present invention will be described in detail.
<The retardation film of the present invention>
The retardation film of the present invention is a retardation film having a cellulose ester film, an optically anisotropic layer in which a rod-like liquid crystal is vertically aligned on one surface thereof and the orientation is fixed, and a back layer on the other surface. The cellulose ester film simultaneously satisfies the following formulas (A1) and (A2), the solvent content is 0.01% by mass or less, and the film forming direction at 23 ° C. and 55% RH (hereinafter abbreviated as MD) modulus CE1 is 1.5~2.5kN / mm ^2, the width direction (hereinafter, abbreviated to TD) elastic modulus CE2 of a 1.8~3.5kN / mm ^2, the modulus of elasticity of the back surface layer BC is characterized by (elastic modulus CE1 + elastic modulus CE2) / 2 <elastic modulus BC.

  In the present invention, the MD and TD elastic moduli of the cellulose ester film, which is a support for providing the optically anisotropic layer, and the elastic modulus of the back layer are manifested in uneven orientation of the optically anisotropic layer due to environmental changes. Has been found to be suppressed.

  Specifically, when the optically anisotropic layer is applied, the optically anisotropic layer has a structure in which the elastic modulus gradually increases from the surface on which the optically anisotropic layer is applied. It has been found that the unevenness of orientation is suppressed.

  Regarding the relationship between the elastic modulus of MD and TD of the cellulose ester film and the alignment unevenness of the optically anisotropic layer, the optically anisotropic layer is fixed after vertical alignment, but the degree to which this fixed state changes depending on the environment. The direction and the direction and the degree and direction of change depending on the environment of the cellulose ester film that is the support are substantially the same in the range of the elastic modulus of the present invention, and as a result, the effect of suppressing the emergence of orientation unevenness is suppressed. Also has.

The elastic modulus of MD of the present invention is preferably 1.8 to 2.3 kN / mm ² , and the elastic modulus of TD is preferably 2.2 to 3.4 kN / mm ² .

  The relationship between the elastic modulus of MD and TD is 1.0 <elastic modulus in the lateral direction / elastic modulus in the film forming direction ≦ 2.0, and 1.05 ≦ elastic modulus in the lateral direction / film forming direction. It is preferable that the elastic modulus is 1.90.

The elastic modulus BC of at least one layer of the cellulose ester back layer is (elastic modulus CE1 + elastic modulus CE2) / 2 <elastic modulus BC, specifically, 3.0 to 6.5 kN / mm ² is preferable. .

  The elastic modulus was conditioned at 23 ° C. and 55% RH for 24 hours, and in accordance with the method described in JIS K7127, using Tensilon RTA-100 manufactured by Orient Test Co., Ltd. The shape of the test piece was No. 1 type test piece, and the test speed was measured under the condition of 10 mm / min.

  The elastic modulus of the coating layers such as the optically anisotropic layer and the back layer was determined by subtracting the elastic modulus of only the cellulose ester film from the whole cellulose ester film after coating.

  The retardation film of the present invention preferably has a thickness of 20 to 80 μm and has the following characteristics.

0nm ≦ Ro ≦ 330nm
−150 nm ≦ Rt ≦ 150 nm
These Ro and Rt are the total of Ro and Rt of the cellulose anisotropic film, the optically anisotropic layer and the back layer in which the rod-like liquid crystal is vertically aligned and fixed in the alignment, and in some cases other intermediate layers.

  The retardation value was measured by adjusting the humidity to a wavelength of 590 nm and 23 ° C. and 55% RH using an automatic birefringence meter KOBRA-21ADH (Oji Scientific Instruments).

In order to obtain the retardation film of the present invention, the cellulose ester film, vertical alignment liquid crystal layer, and back layer described below are preferable.
<Cellulose ester film>
The cellulose ester film of the present invention preferably has the following characteristics.

Transmittance: 80% or more Film thickness: 20-80 μm
0nm ≦ Ro ≦ 330nm
−100 nm ≦ Rt ≦ 340 nm
Ro = (nx−ny) × d
Rt = ((nx + ny) / 2−nz) × d
(Where nx is the refractive index in the slow axis direction in the plane of the cellulose ester film, ny is the refractive index in the direction perpendicular to the slow axis in the plane, nz is the refractive index in the thickness direction, and d is the refractive index in the thickness direction) (Represents the thickness (nm) of the cellulose ester film. The refractive index is measured at 590 nm.)
The refractive index can be obtained at a wavelength of 590 nm under an environment of 23 ° C. and 55% RH using, for example, KOBRA-21ADH (Oji Scientific Instruments).

  The cellulose ester film of the present invention is characterized in that the solvent content is 0.01% by mass or less.

  In cellulose esters, the deterioration of planarity under high temperature and high humidity strongly depends on the amount of solvent contained, because the structure of the substituents varies within a minute region due to the solvent. It is thought that there is.

  Therefore, the cellulose ester film of the present invention is preferably produced by a melt film forming method. Since this method basically does not use a solvent for dissolving the cellulose ester, the residual solvent amount after film-forming and drying (the amount of the solvent that is finally contained in the film) is set to 0% of the entire cellulose ester film. 0.01 mass%.

  Here, the contained solvent is an organic solvent having a boiling point of 120 ° C. or lower used in casting film formation, and is a solvent remaining in the film even in the film state after film formation.

The cellulose ester film of the present invention is characterized by comprising a cellulose ester and an additive as a basic constitution.
<Cellulose ester>
The cellulose ester used in the present invention is a carboxylic acid ester having about 2 to 22 carbon atoms, may be an aromatic carboxylic acid ester, and is particularly preferably a lower fatty acid ester of cellulose.

  The lower fatty acid in the lower fatty acid ester of cellulose means a fatty acid having 6 or less carbon atoms. The acyl group bonded to the hydroxyl group may be linear or branched or may form a ring. Furthermore, another substituent may be substituted.

  In the case of the same degree of substitution, since the film loses its elasticity when the number of carbon atoms is large, the number of carbon atoms is preferably selected from acyl groups having 2 to 6 carbon atoms.

  The cellulose ester of the present invention is required to satisfy the above (A1) and (A2) at the same time. However, Y is a propionyl group, and 0.5 ≦ Y ≦ 2.0 is preferable. 8 ≦ Y ≦ 1.8 is particularly preferable for light leakage.

  The substitution degree range in the present invention can increase the stretching speed, and the elastic modulus can also achieve the range of the present invention.

  The measuring method of the substitution degree of an acyl group can be measured according to ASTM-D817-96.

  The molecular weight of the cellulose ester is preferably 60000-300000, more preferably 70000-200000 in terms of number average molecular weight (Mn). The ratio of weight average molecular weight (Mw) / number average molecular weight (Mn) is preferably 4.0 or less, more preferably 1.4 to 2.3.

  Since the average molecular weight and molecular weight distribution of cellulose ester can be measured using gel permeation chromatography (GPC), the number average molecular weight (Mn) and the weight average molecular weight (Mw) are calculated using this, and the ratio is calculated. be able to.

  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 = 2,300,000-500 calibration curves with 13 samples were used. The 13 samples are preferably used at approximately equal intervals.

  The residual sulfuric acid content in the cellulose ester of the present invention is preferably in the range of 0.1 to 45 ppm in terms of elemental sulfur. These are considered to be contained in the form of salts. When the residual sulfuric acid content exceeds 45 ppm, there is a tendency that deposits on the die lip portion during heat melting increase.

  In addition, there is a tendency to break easily during slitting at the time of hot drawing or after hot drawing. Therefore, the range of 1-30 ppm is more preferable. The residual sulfuric acid content can be measured by the method prescribed in ASTM D817-96.

  The free acid content in the cell ester of the present invention is preferably 1 to 500 ppm. Within the above range, there is no increase in deposits on the die lip and it is difficult to break.

  Furthermore, about this invention, it is preferable that it is the range of 1-100 ppm, and also it becomes difficult to fracture | rupture. A range of 1 to 70 ppm is particularly preferable. The free acid content can be measured by the method prescribed in ASTM D817-96.

  By washing the synthesized cellulose ester more sufficiently than when used in the solution casting method, the residual alkaline earth metal content, residual sulfuric acid content, and residual acid content are within the above ranges. This is preferable.

  In addition to washing with water, cellulose ester can be washed with a poor solvent such as methanol or ethanol, or as a result, a poor solvent and a mixed solvent of a good solvent can be used. Low molecular organic impurities can be removed.

Moreover, it is preferable that the cellulose ester of this invention has few bright spot foreign materials when it is made into a film. The bright spot foreign matter preferably has a bright spot diameter of 0.01 mm or more and 200 pieces / cm ² or less, more preferably 100 pieces / cm ² or less, and preferably 50 pieces / cm ² or less. 30 / cm ² or less, preferably 10 / cm ² or less, and most preferably none.

Moreover, it is preferable that it is 200 pieces / cm < ² > or less also about a bright spot of 0.005-0.01 mm or less, Furthermore, it is preferable that it is 100 pieces / cm < ² > or less, and it is 50 pieces / cm < ² > or less. The number is preferably 30 pieces / cm ² or less, more preferably 10 pieces / cm ² or less, and most preferably none.
<Additives>
In the present invention, when adjusting the elastic modulus of MD and TD within the range of the present invention, the cellulose ester film has at least one of an acrylic polymer and at least one of a pyranose structure or a furanose structure in a range of 12 or less. It contains at least one selected from ester compounds obtained by esterifying all or part of the OH groups of the structure.

  By containing these compounds in a cellulose ester, desired retardation and elastic modulus can be achieved.

<Sugar ester compound>
The cellulose ester film of the present invention preferably uses a sugar ester compound in which at least one pyranose structure or furanose structure is 1 to 12 and all or part of the OH groups in the structure are esterified.

  Examples of the sugar ester compound used in the present invention include glucose, galactose, mannose, fructose, xylose, arabinose, lactose, sucrose, cellobiose, cellotriose, maltotriose, raffinose, etc., particularly both furanose structure and pyranose structure. What has is preferable. An example is sucrose.

  The sugar ester compound used in the present invention is one in which part or all of the hydroxyl groups of the sugar compound are esterified or a mixture thereof.

The sugar ester compound of the present invention is a compound obtained by condensing 1 or more and 12 or less of at least one pyranose structure or furanose structure represented by the following general formula (A). However, R < ₁₁ > -R < ₁₅ >, R < ₂₁ > -R < ₂₅ > represents a C2-C22 acyl group or a hydrogen atom, m and n represent the integer of 0-12 respectively, and m + n represents the integer of 1-12.

R _{11 to} R ₁₅ and R _{21 to} R ₂₅ are preferably a benzoyl group or a hydrogen atom. The benzoyl group may further have a substituent R ₂₆ (p is 0 to 5), and examples thereof include an alkyl group, an alkenyl group, an alkoxyl group, and a phenyl group, and further, these alkyl groups, alkenyl groups, and phenyl groups. May have a substituent. Oligosaccharides can also be produced by the same method as the ester compound of the present invention.

  As a commercial item, monopet SB (Daiichi Kogyo Seiyaku Co., Ltd. product) etc. are mentioned, for example.

<Acrylic polymer>
In the present invention, an acrylic polymer is added to the cellulose ester film. Here, the acrylic polymer includes a methacrylic polymer.

  As an acrylic polymer used in the present invention, when it is contained in a cellulose ester film, it preferably exhibits negative birefringence as a function of the stretching direction, and the structure is not particularly limited. A polymer having a weight average molecular weight of 500 to 30,000 obtained by polymerizing an ethylenically unsaturated monomer is preferred.

  The acrylic polymer having a weight average molecular weight of 500 or more and 30000 or less used in the present invention may be an acrylic polymer having an aromatic ring in the side chain or an acrylic polymer having a cyclohexyl group in the side chain.

  When the weight average molecular weight of the polymer is 500 or more and 30000 or less and the composition of the polymer is controlled, for example, when the cellulose ester film is a particularly preferable cellulose ester film in the present invention, the cellulose ester and the polymer The compatibility with can be improved.

  As for the acrylic polymer having an aromatic ring in the side chain or the acrylic polymer having a cyclohexyl group in the side chain, if the weight average molecular weight is 500 or more and 10,000 or less, in addition to the above, cellulose after film formation The transparency of the ester film is excellent, the moisture permeability is extremely low, and it 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 by a method that does not increase the molecular weight too much.

  In particular, the acrylic polymer used in the cellulose ester film of the present invention includes an ethylenically unsaturated monomer Xa having no aromatic ring and a hydroxyl group in the molecule, and an ethylene having a hydroxyl group and no aromatic ring in the molecule. Polymer X having a weight average molecular weight of 2,000 to 30,000 obtained by copolymerization of a polymerizable unsaturated monomer Xb and a copolymerizable ethylenically unsaturated monomer excluding Xa and Xb, or ethylene having no aromatic ring The polymer Y is preferably a polymer Y having a weight average molecular weight of 500 or more and 3000 or less, obtained by polymerizing the polymerizable unsaturated monomer Ya and an ethylenically unsaturated monomer copolymerizable with Ya.

[Polymer X, Polymer Y]
The method for adjusting Ro and Rt of the cellulose ester film according to the present invention includes an ethylenically unsaturated monomer Xa having no aromatic ring and a hydroxyl group in the molecule, and ethylene having a hydroxyl group and no aromatic ring in the molecule. High molecular weight polymer X having a weight average molecular weight of 2,000 to 30,000 obtained by copolymerization of the polymerizable unsaturated monomer Xb and a copolymerizable ethylenically unsaturated monomer excluding Xa and Xb, and more preferably, Contains a low molecular weight polymer Y having a weight average molecular weight of 500 to 3,000 obtained by polymerizing an ethylenically unsaturated monomer Ya having no aromatic ring and an ethylenically unsaturated monomer copolymerizable with Ya It is preferable.

  The polymer X used in the present invention includes an ethylenically unsaturated monomer Xa having no aromatic ring and a hydroxyl group in the molecule and an ethylenically unsaturated monomer Xb having no hydroxyl ring in the molecule and having a hydroxyl group, Xa and Xb. Is a polymer having a weight average molecular weight of 2000 or more and 30000 or less obtained by copolymerization with a copolymerizable ethylenically unsaturated monomer other than.

  Preferably, Xa is an acrylic or methacrylic monomer having no aromatic ring and hydroxyl group in the molecule, and Xb is an acrylic or methacrylic monomer having no aromatic ring and having a hydroxyl group in the molecule.

  The polymer X used in the present invention is represented by the following general formula (X).

Formula (X)
-[Xa] m- [Xb] n- [Xc] p-
In the general formula (X), Xa represents an ethylenically unsaturated monomer having no aromatic ring and hydroxyl group in the molecule, and Xb represents an ethylenically unsaturated monomer having no aromatic ring and having a hydroxyl group in the molecule. Xc represents a copolymerizable ethylenically unsaturated monomer excluding Xa and Xb. m, n, and p each represent a molar composition ratio. However, m ≠ 0 and m + n + p = 100.

  Furthermore, the polymer X is preferably a polymer represented by the following general formula (X-1).

Formula (X-1)
_{- [CH 2 -C (-R1)} (- CO 2 R2)] m- [CH 2 -C (-R3) (- CO 2 R4-OH) -] n- [Xc] p-
In the general formula (X-1), R1 and R3 each represent a hydrogen atom or a methyl group. R2 represents an alkyl group having 1 to 12 carbon atoms or a cycloalkyl group. R4 is _{-CH 2 -, - C 2 H} 4 - or _-C 3 _{H 6} - represents a. Xc _{is, [CH 2 -C (-R1)} (- CO 2 R2)] representing the a polymerizable monomer unit or _{[CH 2 -C (-R3) (} - - CO 2 R4-OH)]. m, n, and p represent a molar composition ratio. However, m ≠ 0 and m + n + p = 100.

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

  In X, the hydroxyl group means not only a hydroxyl group but also a group having an ethylene oxide chain.

  Examples of the ethylenically unsaturated monomer Xa having no aromatic ring and hydroxyl 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), etc. The thing changed into acid ester can be mentioned.

  Among these, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, and propyl methacrylate (i-, n-) are preferable.

  The ethylenically unsaturated monomer Xb having no hydroxyl ring in the molecule and having a hydroxyl group is preferably acrylic acid or methacrylic acid ester as a monomer unit having a hydroxyl group, such as 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 these acrylic acids with methacrylic acid. Preferred are acrylic acid (2-hydroxyethyl) and methacrylic acid (2-hydroxyethyl), acrylic acid (2-hydroxypropyl), and acrylic acid (3-hydroxypropyl).

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

  The molar composition ratio m: n of Xa and Xb 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 high molecular weight polymer X, the weight average molecular weight is more preferably from 5,000 to 30,000, and even more preferably from 8,000 to 25,000.

  By setting the weight average molecular weight to 5000 or more, advantages such as little dimensional change under high temperature and high humidity of the cellulose ester film are obtained, which is preferable.

  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 are suppressed.

  The weight average molecular weight of the polymer X according to 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 from room temperature to 130 ° C., preferably from 50 ° C. to 100 ° C., and this temperature or the polymerization reaction time can be adjusted.

  In addition, a weight average molecular weight etc. can be calculated | required according to the above-mentioned method.

  The low molecular weight polymer Y 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 preferred because the residual monomer in the polymer is reduced.

  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 used in the present invention is represented by the following general formula (Y).

General formula (Y)
-[Ya] k- [Yb] q-
In the general formula (Y), Ya represents an ethylenically unsaturated monomer having no aromatic ring, and Yb represents an ethylenically unsaturated monomer copolymerizable with Ya. k and q each represent a molar composition ratio. However, k ≠ 0 and k + q = 100.

  The polymer Y according to the present invention is more preferably a polymer represented by the following general formula (Y-1).

General formula (Y-1)
_{- [CH 2 -C (-R5)} (- CO 2 R6)] k- [Yb] q-
In the general formula (Y-1), R5 represents a hydrogen atom or a methyl group, respectively. R6 represents an alkyl group having 1 to 12 carbon atoms or a cycloalkyl group. Yb represents a monomer unit copolymerizable with [CH ₂ —C (—R 5) (— CO ₂ R 6)]. k and q each represent a molar composition ratio. However, k ≠ 0 and k + q = 100.

Yb is a _{Ya [CH 2 -C (-R5)} (- CO 2 R6)] and is not particularly limited as long as it is copolymerizable ethylenically unsaturated monomers. Yb may be plural. k + q = 100, q is preferably 0-30.

  The ethylenically unsaturated monomer Ya constituting the polymer Y obtained by polymerizing the 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-), acrylic Acid heptyl (n-, i-), octyl acrylate (n-, i-), nonyl acrylate (n-, i-), myristyl acrylate (n-, i-), cyclohexyl acrylate, acrylic acid ( 2-ethylhexyl), 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 weight as uniform as possible by a method that does not increase the molecular weight too much.

  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 disclosed in JP 2000-128911 or 2000-344823 Examples thereof include a compound having one thiol group and a secondary hydroxyl group, or a bulk polymerization method using a polymerization catalyst in which the compound and an organometallic compound are used in combination. Used.

  In particular, the polymer Y is preferably a polymerization method using a compound having a thiol group and a secondary hydroxyl group in the molecule as a chain transfer agent. In this case, the terminal of the polymer Y has a hydroxyl group and a thioether resulting from the polymerization catalyst and the chain transfer agent. The compatibility between Y and cellulose ester can be adjusted by this terminal residue.

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

  The hydroxyl value is measured in accordance with JIS K 0070 (1992). This hydroxyl value is defined as the number of mg of potassium hydroxide required to neutralize acetic acid bonded to a hydroxyl 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 is calculated by the following formula.

Hydroxyl value = {(BC) × f × 28.05 / X} + D
In the formula, B is the amount (ml) of 0.5 mol / L potassium hydroxide ethanol solution used for the blank test, C is the amount (ml) of 0.5 mol / L potassium hydroxide ethanol solution used for titration, f is a factor of a 0.5 mol / L potassium hydroxide ethanol solution, D is an acid value, and 28.05 is 1/2 of 1 mol amount 56.11 of potassium hydroxide.

  The above-mentioned polymer X and polymer Y are both excellent in compatibility with cellulose ester, excellent in productivity without evaporation and volatilization, good retention as a protective film for polarizing plates, low moisture permeability, and dimensional stability. Excellent in properties.

The content of the polymer X and the polymer Y in the cellulose ester film is preferably in a range satisfying the following formulas (i) and (ii). When the content of the polymer X is Xg (mass% = (mass of polymer X / mass of cellulose ester) × 100) and the content of 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 (Xg + Yg) in the formula (i) is 10 to 35% by mass. If the polymer X and the polymer Y are 5 mass% or more as a total amount with respect to the total mass of the cellulose ester, the polymer X and the polymer Y have a sufficient effect for adjusting the retardation value Rt.

  The polymer X and the polymer Y are directly added and kneaded as a material constituting the melting described later.

The cellulose ester film in the present invention includes a plasticizer that imparts processability to the film, an antioxidant that prevents deterioration of the film, an ultraviolet absorber that imparts an ultraviolet absorbing function, and fine particles that impart slipperiness to the film (matting agent). ), Additives such as a retardation adjusting agent for adjusting the retardation of the film may be contained.
<Other additives>
As other additives, it is necessary to appropriately select a plasticizer.
<Plasticizer>
In the production of the cellulose ester film according to the present invention, it is preferable that the film forming material contains at least one plasticizer.

  In the present invention, plasticizers can be used alone or in admixture of two or more, but at least one plasticizer has a structure in which an organic acid and a trihydric or higher alcohol are condensed and has a molecular weight of 350 to 1500. It is preferable that it is an agent.

  Other plasticizers that can be used are not particularly limited, but are preferably polyhydric alcohol ester plasticizers, aromatic-terminated polyester plasticizers, glycolate plasticizers, phthalate ester plasticizers, fatty acid esters. It is selected from system plasticizers, polymer plasticizers, sugar ester compounds and the like.

  If the amount of the plasticizer used is less than 1% by mass relative to the cellulose derivative, the effect of reducing the moisture permeability of the film is small, which is not preferable. If the amount exceeds 20% by mass, the physical properties of the film at high temperature durability deteriorate. -20 mass% is preferable. Hereinafter, preferred plasticizers will be described.

(Polyhydric ester plasticizer)
The polyhydric alcohol ester plasticizer of the present invention is an ester of an organic acid and a polyhydric alcohol, and the organic acid is represented by the following general formula (1).

In the formula, R _{1 to} R ₅ represent a hydrogen atom or a cycloalkyl group, an aralkyl group, an alkoxy group, a cycloalkoxy group, an aryloxy group, an aralkyloxy group, an acyl group, a carbonyloxy group, an oxycarbonyl group, or an oxycarbonyloxy group. These may be further substituted. L represents a linking group and represents a substituted or unsubstituted alkylene group, an oxygen atom, or a direct bond.

The cycloalkyl group represented by R ₁ to R _5, preferably a cycloalkyl group having 3 to 8 carbon atoms, specifically cyclopropyl, cyclopentyl, groups such as cyclohexyl. These groups may be substituted, and preferred substituents include halogen atoms such as chlorine atom, bromine atom, fluorine atom, hydroxyl group, alkyl group, alkoxy group, cycloalkoxy group, aralkyl group (this phenyl group). The group may be further substituted with an alkyl group or a halogen atom), an alkenyl group such as a vinyl group or an allyl group, or a phenyl group (this phenyl group may be further substituted with an alkyl group or a halogen atom). Phenoxy group (this phenyl group may be further substituted by an alkyl group or a halogen atom), an acyl group having 2 to 8 carbon atoms such as an acetyl group or a propionyl group, an acetyloxy group, or a propionyloxy group. And an unsubstituted carbonyloxy group having 2 to 8 carbon atoms such as a group.

The aralkyl group represented by R _{1 to} R ₅ represents a group such as a benzyl group, a phenethyl group, and a γ-phenylpropyl group, and these groups may be substituted. Preferred substituents include The group which may be substituted with the said cycloalkyl group can be mentioned similarly.

Examples of the alkoxy group represented by R _{1 to} R ₅ include an alkoxy group having 1 to 8 carbon atoms, specifically, methoxy, ethoxy, n-propoxy, n-butoxy, n-octyloxy, isopropoxy. , Alkoxy groups such as isobutoxy, 2-ethylhexyloxy, or t-butoxy.

  These groups may be substituted, and preferred substituents include halogen atoms such as chlorine atom, bromine atom, fluorine atom, hydroxyl group, alkoxy group, cycloalkoxy group, aralkyl group (this phenyl group). May be substituted with an alkyl group or a halogen atom), an alkenyl group, a phenyl group (this phenyl group may be further substituted with an alkyl group or a halogen atom), an aryloxy group (for example, phenoxy) An acyl group such as an acetyl group or a propionyl group, or an aryl group such as an acetyloxy group or a propionyloxy group (the phenyl group may be further substituted with an alkyl group or a halogen atom). Arylcarbonyl groups such as unsubstituted acyloxy groups and benzoyloxy groups Shi group.

Examples of the cycloalkoxy group represented by R _{1 to} R ₅ include an unsubstituted cycloalkoxy group having 1 to 8 carbon atoms, specifically cyclopropyloxy, cyclopentyloxy, cyclohexyloxy. And the like.

  In addition, these groups may be substituted, and preferred substituents include the same groups that may be substituted with the cycloalkyl group.

Examples of the aryloxy group represented by R _{1 to} R ₅ include a phenoxy group, and the phenyl group includes a substituent that may be substituted with the cycloalkyl group such as an alkyl group or a halogen atom. May be substituted.

Examples of the aralkyloxy group represented by R _{1 to} R ₅ include a benzyloxy group and a phenethyloxy group, and these substituents may be further substituted. Preferred substituents include the above cycloalkyl The group which may be substituted with a group can be mentioned similarly.

Examples of the acyl group represented by R _{1 to} R ₅ include an unsubstituted acyl group having 2 to 8 carbon atoms such as an acetyl group and a propionyl group (the hydrocarbon group of the acyl group includes alkyl, alkenyl, alkynyl). These substituents may be further substituted, and preferred substituents include the same groups that may be substituted with the cycloalkyl group.

As the carbonyloxy group represented by R _{1 to} R ₅ , an unsubstituted acyloxy group having 2 to 8 carbon atoms such as acetyloxy group and propionyloxy group (the hydrocarbon group of the acyl group is alkyl, alkenyl, alkynyl). And arylcarbonyloxy groups such as a benzoyloxy group, and these groups may be further substituted with the same groups as those which may be substituted with the cycloalkyl group.

The oxycarbonyl group represented by R _{1 to} R ₅ represents an alkoxycarbonyl group such as a methoxycarbonyl group, an ethoxycarbonyl group or a propyloxycarbonyl group, or an aryloxycarbonyl group such as a phenoxycarbonyl group.

  These substituents may be further substituted, and preferred examples of the substituent include the same groups that may be substituted with the cycloalkyl group.

The oxycarbonyloxy group represented by R _{1 to} R ₅ represents an alkoxycarbonyloxy group having 1 to 8 carbon atoms such as a methoxycarbonyloxy group, and these substituents may be further substituted and are preferably substituted. Examples of the group include the same groups that may be substituted on the cycloalkyl group.

Any one of R _{1 to} R ₅ may be connected to each other to form a ring structure.

The linking group represented by L represents a substituted or unsubstituted alkylene group, an oxygen atom, or a direct bond, and the alkylene group is a group such as a methylene group, an ethylene group, or a propylene group. These groups may be further substituted with the groups mentioned as groups that may be substituted with the groups represented by R _{1 to} R ₅ .

  Among these, a direct bond and an aromatic carboxylic acid are particularly preferable as the linking group represented by L.

In addition, the organic acid represented by the general formula (1) constituting the ester compound serving as a plasticizer in the present invention includes at least R ₁ or R ₂ having the alkoxy group, acyl group, oxycarbonyl group, carbonyl group. Those having an oxy group or an oxycarbonyloxy group are preferred. A compound having a plurality of substituents is also preferred.

  In the present invention, the organic acid for substituting the hydroxyl group of the trivalent or higher alcohol may be a single type or a plurality of types.

  In the present invention, the trihydric or higher alcohol compound that reacts with the organic acid represented by the general formula (1) to form a polyhydric alcohol ester compound is preferably a 3-20 valent aliphatic polyhydric alcohol. In the present invention, the trihydric or higher alcohol is preferably represented by the following general formula (2).

General formula (2) R '-(OH) m
In the formula, R ′ represents an m-valent organic group, m represents a positive integer of 3 or more, and the OH group represents an alcoholic hydroxyl group. Particularly preferred is a polyhydric alcohol having 3 or 4 as m.

  Examples of preferred polyhydric alcohols include the following, but the present invention is not limited to these.

  Adonitol, arabitol, 1,2,4-butanetriol, 1,2,3-hexanetriol, 1,2,6-hexanetriol, glycerin, diglycerin, erythritol, pentaerythritol, dipentaerythritol, tripentaerythritol, ga Examples include lactitol, inositol, mannitol, 3-methylpentane-1,3,5-triol, pinacol, sorbitol, trimethylolpropane, trimethylolethane, and xylitol.

  In particular, glycerin, trimethylolethane, trimethylolpropane, and pentaerythritol are preferable.

  The ester of the organic acid represented by the general formula (1) and the trihydric or higher polyhydric alcohol represented by the general formula (2) can be synthesized by a known method. Or although the typical synthesis example was shown, the organic acid represented by the said General formula (1) and the polyhydric alcohol represented by General formula (2) are condensed and esterified in presence of an acid, for example, In addition, there are a method in which an organic acid is preliminarily formed as an acid chloride or an acid anhydride and a reaction with a polyhydric alcohol, a method in which a phenyl ester of an organic acid is reacted with a polyhydric alcohol, and the like. It is preferable to select an efficient method.

  As a plasticizer comprising an organic acid represented by the general formula (1) and an ester of a trihydric or higher polyhydric alcohol represented by the general formula (2), a compound represented by the following general formula (3) is preferable. .

In the formula, R _{6 to} R ₂₀ represent a hydrogen atom or a cycloalkyl group, an aralkyl group, an alkoxy group, a cycloalkoxy group, an aryloxy group, an aralkyloxy group, an acyl group, a carbonyloxy group, an oxycarbonyl group, or an oxycarbonyloxy group. These may be further substituted. R ₂₁ represents a hydrogen atom or an alkyl group.

The cycloalkyl group, the aralkyl group, the alkoxy group, the cycloalkoxy group, the aryloxy group, the aralkyloxy group, the acyl group, the carbonyloxy group, the oxycarbonyl group, and the oxycarbonyloxy group of R _{6 to} R ₂₀ are represented by the general formula ( The same group as R < ₁ > -R < ₅ > of 1) is mentioned.

  Below, the specific compound of the polyhydric alcohol ester concerning this invention is illustrated.

<Aromatic terminal polyester plasticizer>
In the present invention, an aromatic terminal polyester plasticizer represented by the following general formula (I) can be used.

General formula (I) B- (GA) n-GB
(In the formula, B is an arylcarboxylic 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 alkylene dicarboxylic acid residue having 4 to 12 carbon atoms or an aryl dicarboxylic acid residue having 6 to 12 carbon atoms, and n represents an integer of 1 or more.)
In general formula (I), an arylcarboxylic acid residue represented by B and an alkylene glycol residue or oxyalkylene glycol residue or arylglycol residue represented by G, an alkylenedicarboxylic acid residue or aryldicarboxylic acid represented by A And is obtained by the same reaction as a normal polyester compound.

  Examples of the arylcarboxylic acid component of the aromatic-terminated polyester plasticizer used in the present invention include benzoic acid, paratertiarybutylbenzoic acid, orthotoluic acid, metatoluic acid, p-toluic acid, dimethylbenzoic acid, ethylbenzoic acid, There are normal propyl benzoic acid, aminobenzoic acid, acetoxybenzoic 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 aromatic terminal polyester plasticizer that can be used in the present invention include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, and 1,2-butanediol. 1,3-butanediol, 1,2-propanediol, 2-methyl 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl-1,3-propane Diol (neopentyl glycol), 2,2-diethyl-1,3-propanediol (3,3-dimethylolpentane), 2-n-butyl-2-ethyl-1,3-propanediol (3,3-di) Methylol heptane), 3-methyl-1,5-pentanediol 1,6-hexanediol, 2,2,4-trimethyl 1, -Pentanediol, 2-ethyl 1,3-hexanediol, 2-methyl 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-octadecanediol, etc. Glycol is used as one or a mixture of two or more.

  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 aromatic terminal polyester plasticizer include diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, and tripropylene glycol. 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 aromatic terminal polyester plasticizer include succinic acid, maleic acid, fumaric acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, and dodecanedicarboxylic acid. These are each used as one or a mixture of two or more.

  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.

  In the aromatic terminal polyester plasticizer used in the present invention, n is preferably 1 or more and 100 or less, and the number average molecular weight is preferably 300 to 1500, more preferably 400 to 1000. .

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

  The aromatic terminal polyester plasticizer represented by the general formula (I) of the present invention is preferably contained in an amount of 0.5 to 30% by mass with respect to the cellulose ester.

  Although the specific compound of the aromatic terminal polyester plasticizer which can be used for this invention below is shown, this invention is not limited to this.

(Polymer plasticizer)
The cellulose ester film of the present invention preferably uses a polymer plasticizer other than the acrylic polymer.

  Specifically, aliphatic hydrocarbon polymers, alicyclic hydrocarbon polymers, polyvinyl isobutyl ether, vinyl polymers such as poly N-vinyl pyrrolidone, copolymers of methyl methacrylate and N-vinyl pyrrolidone (for example, Copolymerization ratio (any ratio between 1:99 and 99: 1), polystyrene, styrene-based polymers such as poly-4-hydroxystyrene, polybutylene succinate, polyesters such as polyethylene terephthalate, polyethylene naphthalate, polyethylene oxide, polypropylene Examples include polyethers such as oxides, polyamides, polyurethanes, and polyureas.

  The number average molecular weight is preferably about 1,000 to 500,000, particularly preferably 5,000 to 200,000. If it is 1,000 or less, the volatility becomes large, and if it exceeds 500,000, the plasticizing ability tends to decrease, which may adversely affect the mechanical properties of the cellulose ester retardation film.

  These polymer plasticizers may be a homopolymer composed of one monomer repeating unit or a copolymer having a repeating structure of a plurality of monomers. Two or more of the above polymers may be used in combination.

  Further, the method for measuring the amount of plasticizer on the surface is not particularly limited. For example, a knife or the like is used to quantitatively analyze the surface of the film by cutting it about 20 nm or the amount of plasticizer in the thickness direction of the film is measured by IR or atomic absorption It is quantified using a method such as scanning with the above.

Examples of the acrylic polymer of the present invention include Delpet 60N, 80N (Asahi Kasei Chemicals Corporation), Dianal BR52, BR80, BR83, BR85, BR88 (Mitsubishi Rayon Co., Ltd.), KT75 (Electrochemical Industry ( Etc.).
<Antioxidant>
In this invention, what is generally known can be used as an antioxidant. In particular, lactone, sulfur, phenol, double bond, hindered amine, and phosphorus compounds can be preferably used.

  For example, the thing containing what is marketed by the brand name "IrgafosXP40" and "IrgafosXP60" from Ciba Japan KK is preferable.

  The phenolic compound preferably has a 2,6-dialkylphenol structure. For example, Ciba Japan Co., Ltd., “Irganox 1076”, “Irganox 1010”, ADEKA “ADEKA STAB AO-50” And those commercially available.

  Examples of the phosphorus compound include Sumitizer GP (AO2) from Sumitomo Chemical Co., Ltd., “ADK STAB PEP-24G”, “ADK STAB PEP-36” (AO1) and “ADK STAB 3010” from ADEKA Co., Ltd. What is marketed by the brand name "IRGAFOS P-EPQ" (AO4) from Ciba Japan Co., Ltd. and "GSY-P101" (AO3) from Sakai Chemical Industry Co., Ltd. is preferable.

  As the hindered amine compound, for example, those commercially available from Ciba Japan Co., Ltd. under the trade names of “Tinvin 144 (AO2)” and “Tinvin 770” and ADEKA Co., Ltd. as “ADK STAB LA-52” are preferable.

  The sulfur compound is preferably commercially available from Sumitomo Chemical Co., Ltd. under the trade names “Sumilizer TPL-R” and “Sumilizer TP-D”.

  The above-mentioned double bond type compounds are preferably those commercially available from Sumitomo Chemical Co., Ltd. under the trade names of “Sumilizer GM” (AO5) and “Sumilizer GS” (AO3).

  Furthermore, it is possible to contain a compound having an epoxy group as described in US Pat. No. 4,137,201 as an acid scavenger.

  The amount of these antioxidants and the like to be appropriately added is determined in accordance with the process at the time of recycling, but generally 0.05 to 20% by mass, preferably with respect to the resin as the main raw material of the film Is added in the range of 0.1 to 1% by mass.

These antioxidants can obtain a synergistic effect by using several different types of compounds in combination rather than using only one kind. For example, the combined use of lactone, phosphorus, phenol and double bond compounds is preferred.
<Retardation adjuster>
The cellulose ester film of the present invention may contain a compound for adjusting the retardation.

  As the compound to be added for adjusting the retardation, an aromatic compound having two or more aromatic rings as described in EP 911,656A2 can also be used.

Two or more aromatic compounds may be used in combination. The aromatic ring of the aromatic compound includes an aromatic heterocyclic ring in addition to the aromatic hydrocarbon ring. An aromatic heterocyclic ring is particularly preferred, and the aromatic heterocyclic ring is generally an unsaturated heterocyclic ring. Of these, compounds having a 1,3,5-triazine ring are particularly preferred.
<Colorant>
In the present invention, it is preferable to use a colorant. The colorant means a dye or a pigment. In the present invention, the colorant means an effect of making the color tone of a liquid crystal screen blue, adjusting the yellow index, and reducing haze.

Various dyes and pigments can be used as the colorant, but anthraquinone dyes, azo dyes, phthalocyanine pigments and the like are effective.
<Ultraviolet absorber>
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.
<Matting agent>
In the present invention, it is preferable to add a matting agent in order to impart film slipperiness.

  As the matting agent used in the present invention, any inorganic compound or organic compound may be used as long as it has heat resistance at the time of melting without impairing the transparency of the obtained film. For example, talc, mica, zeolite, diatomaceous earth, Calcined siliceous clay, kaolin, sericite, bentonite, smectite, clay, silica, quartz powder, glass beads, glass powder, glass flakes, milled fiber, wollastonite, boron nitride, boron carbide, titanium boride, magnesium carbonate, Heavy calcium carbonate, light calcium carbonate, calcium silicate, aluminum silicate, magnesium silicate, magnesium aluminosilicate, alumina, silica, zinc oxide, titanium dioxide, iron oxide, magnesium oxide, zirconium oxide, aluminum hydroxide, calcium hydroxide, water Magnesium oxide Beam, calcium sulfate, barium sulfate, silicon carbide, aluminum carbide, titanium carbide, aluminum nitride, silicon nitride, titanium nitride, and white carbon.

  These matting agents can be used alone or in combination of two or more. By using particles having different particle sizes and shapes (for example, acicular and spherical), both transparency and slipperiness can be made highly compatible.

  Among these, silicon dioxide is particularly preferably used since it has a refractive index close to that of cellulose ester and is excellent in transparency (haze). Specific examples of silicon dioxide include Aerosil 200V, Aerosil R972V, Aerosil R972, R974, R812, 200, 300, R202, OX50, TT600 (above Nippon Aerosil Co., Ltd.), Sea Hoster KEP-10, Sea Hoster KEP-30, Commercial products having trade names such as Seahoster KEP-50 (above, made by Nippon Shokubai Co., Ltd.), Silo Hovic 100 (made by Fuji Silysia), Nip Seal E220A (made by Nippon Silica Kogyo), Admafine SO (made by Admatechs), etc. Can be preferably used.

  The shape of the particles can be used without particular limitation, such as indefinite shape, needle shape, flat shape, spherical shape, etc. However, the use of spherical particles is particularly preferable because the transparency of the resulting film can be improved. When the particle size is close to the wavelength of visible light, light is scattered and the transparency is deteriorated. Therefore, the particle size is preferably smaller than the wavelength of visible light, and more preferably ½ or less of the wavelength of visible light. .

  If the size of the particles is too small, the slipperiness may not be improved, so the range of 80 nm to 180 nm is particularly preferable.

The particle size means the size of the aggregate when the particle is an aggregate of primary particles. Moreover, when a particle is not spherical, it means the diameter of a circle corresponding to the projected area.
<Viscosity reducing agent>
In the present invention, a hydrogen bonding solvent can be added for the purpose of reducing the melt viscosity. The hydrogen bonding solvent is J.I. N. As described in Israel Ativili, “Intermolecular Forces and Surface Forces” (Takeshi Kondo, Hiroyuki Oshima, Maglow Hill Publishing, 1991) and electrically negative atoms (oxygen, nitrogen, fluorine, chlorine) An organic solvent capable of producing a hydrogen atom-mediated “bond” between a hydrogen atom covalently bonded to an electronegative atom, ie, a bond having a large bond moment and containing hydrogen, such as O—H (Oxygen hydrogen bond), N—H (nitrogen hydrogen bond), and organic solvent that can arrange adjacent molecules by including F—H (fluorine hydrogen bond).

  These have the ability to form stronger hydrogen bonds with cellulose than intermolecular hydrogen bonds of cellulose resin. In the melt casting method performed in the present invention, the glass transition temperature of the cellulose resin used alone is higher than that. The melting temperature of the cellulose resin composition can be lowered by adding a hydrogen bonding solvent.

  Alternatively, the melt viscosity of the cellulose resin composition containing a hydrogen bonding solvent can be lowered than that of the cellulose resin at the same melting temperature.

  Examples of the hydrogen bonding solvent include alcohols: for example, methanol, ethanol, propanol, isopropanol, n-butanol, sec-butanol, t-butanol, 2-ethylhexanol, heptanol, octanol, nonanol, dodecanol, ethylene glycol, Propylene glycol, hexylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, methyl cellosolve, ethyl cellosolve, butyl cellosolve, hexyl cellosolve, glycerin, etc., ketones: acetone, methyl ethyl ketone, etc., carboxylic acids: eg formic acid, acetic acid, propionic acid, Butyric acid, etc., ethers: eg, diethyl ether, tetrahydrofuran, dioxane, etc., Pyrrolidones: eg, N-methyl Pyrrolidone, etc., amines: for example, can be exemplified trimethylamine, pyridine, etc., and the like.

  These hydrogen bonding solvents can be used alone or in admixture of two or more. Among these, alcohol, ketone, and ether are preferable, and methanol, ethanol, propanol, isopropanol, octanol, dodecanol, ethylene glycol, glycerin, acetone, and tetrahydrofuran are particularly preferable.

  Furthermore, water-soluble solvents such as methanol, ethanol, propanol, isopropanol, ethylene glycol, glycerin, acetone, and tetrahydrofuran are particularly preferable. Here, water-soluble means that the solubility in 100 g of water is 10 g or more.

These solvents are volatilized at the time of melt film formation, and finally the content of the solvent is 0.01% by mass or less.
<Melt casting method>
The melt casting film formation in the present invention is a method in which a composition containing additives such as cellulose ester and a plasticizer is heated and melted to a temperature showing fluidity, and then a melt containing fluid cellulose ester is cast. This is defined as melt film formation.

More specifically, the heating and melting molding method can be classified into a melt extrusion molding method, a press molding method, an induction method, an injection molding method, a blow molding method, a stretch molding method, and the like. Among these, in order to obtain a cellulose ester film excellent in mechanical strength and surface accuracy, the melt extrusion method is excellent.
<Film forming method>
Hereinafter, the film forming method will be described.

(Process for producing molten pellets of cellulose ester and additives)
It is preferable that a plurality of raw materials used for melt extrusion are usually kneaded and pelletized in advance.

  Pelletization may be performed by a known method. For example, dry cellulose ester, plasticizer, and other additives are fed to an extruder using a feeder, kneaded using a single or twin screw extruder, and extruded from a die into a strand. Can be done by water cooling or air cooling and cutting.

  It is important to dry the raw material before extruding to prevent decomposition of the raw material. In particular, since the cellulose ester easily absorbs moisture, it is preferable to dry it at 70 to 140 ° C. for 3 hours or more with a dehumidifying hot air dryer or a vacuum dryer to keep the moisture content at 200 ppm or less, and further 100 ppm or less.

  The additives may be mixed before being supplied to the extruder, or may be supplied by individual feeders. A small amount of additives such as antioxidants are preferably mixed in advance in order to mix more uniformly.

  Mixing of the antioxidants may be performed by mixing solids, and if necessary, the antioxidant may be dissolved in a solvent, impregnated with cellulose ester and mixed, or sprayed and mixed. Also good.

A vacuum nauter mixer or the like is preferable because it can be mixed at the same time. Further, if the contact with air, such as the exit from the feeder unit and the die, can be preferably in an atmosphere such as dehumidified air and dehumidified N ₂ gas.

  In addition, it is preferable to keep the supply hopper and the like to the extruder warm because moisture absorption can be prevented.

  Matting agents, UV absorbers, and the like may be applied to the obtained pellets or added in an extruder during film formation.

  The extruder is preferably processed at as low a temperature as possible so as to be able to be pelletized so that the shearing force is suppressed and the resin does not deteriorate (decrease in molecular weight, coloring, gel formation, etc.). For example, in the case of a twin screw extruder, it is preferable to rotate in the same direction using a deep groove type screw. From the uniformity of kneading, the meshing type is preferable.

  Kneader discs can improve kneadability, but care must be taken against shearing heat generation. Mixability is sufficient without using a kneader disk. The suction from the vent hole may be performed as necessary. Since there is almost no volatile component at low temperatures, there may be no vent hole.

  The color of the pellet is preferably such that the b * value, which is an index of yellowness, is in the range of -5 to 10, more preferably in the range of -1 to 8, and in the range of -1 to 5. More preferred.

  The b * value can be measured with a spectrocolorimeter CM-3700d (manufactured by Konica Minolta Sensing Co., Ltd.) with a light source of D65 (color temperature 6504K) and a viewing angle of 10 °.

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

(Process of extruding a melt of cellulose ester and additive from the die)
The polymer dried after dehumidifying hot air, vacuum or reduced pressure was removed using a uniaxial or biaxial extruder, the melting temperature during extrusion was about 200 to 300 ° C, and filtered through a leaf disk type filter to remove foreign matter. Then, it is cast into a film from a T die and solidified on a cooling roll.

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

  The extrusion flow rate is preferably performed stably by introducing a gear pump or the like. Further, a stainless fiber sintered filter is preferably used as a filter used for removing foreign substances.

  The stainless steel fiber sintered filter is a united stainless steel fiber body that is intricately intertwined and compressed, and the contact points are sintered and integrated. The density of the fiber is changed depending on the thickness of the fiber and the amount of compression, and the filtration accuracy is improved. Can be adjusted.

  It is preferable to use a multilayer body in which the filtration accuracy is repeated coarsely and densely multiple times. Further, it is preferable to adopt a configuration in which the filtration accuracy is sequentially increased or a method in which coarse and dense filtration accuracy is repeated, so that the filtration life of the filter can be extended and the accuracy of capturing foreign matters and gels can be improved.

  If flaws or foreign matter adhere to the die, streaky defects may occur. Such defects are also referred to as die lines, but in order to reduce surface defects such as die lines, it is preferable that the piping from the extruder to the die has a structure in which the resin retention portion is minimized. It is preferable to use a die that has as few scratches as possible inside the lip.

  The inner surface that contacts the molten resin such as an extruder or a die is preferably subjected to surface treatment that makes it difficult for the molten resin to adhere to the surface by reducing the surface roughness or using a material having a low surface energy. Specifically, a hard chrome plated or ceramic sprayed material is polished so that the surface roughness is 0.2 S or less.

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

(Process of casting while pressing the melt extruded from the die between the cooling roll and the elastic touch roll)
The film temperature on the touch roll side when the film is nipped between the cooling roll and the elastic touch roll is preferably Tg or more and Tg + 110 ° C. or less of the film. A well-known roll can be used for the roll which has the elastic body surface used for such a purpose.

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

(Stretching process)
In the present invention, the film obtained as described above passes through the step of contacting the cooling roll, and then is further stretched in MD and TD at a stretching speed of 400% / min to 1500% / min, and at least the film is produced. It is preferable to stretch 50% to 200% in either the film direction or the width direction.

  This stretching step determines the elastic modulus of MD and TD of the present invention.

  As a method of stretching, a known roll stretching machine or tenter can be preferably used.

  It is preferable that the stretching temperature is usually performed in a temperature range of Tg to Tg + 60 ° C. of the resin constituting the film.

  The glass transition temperature Tg of the film constituting material can be controlled by varying the material type constituting the film and the ratio of the constituting material. When producing a retardation film, Tg is 110 ° C. or higher, preferably 125 ° C. or higher.

  If the Tg of the film is too high, the temperature is increased when the film constituent material is made into a film, so that the energy consumption for heating is increased, and the material itself may be decomposed when it is made into a film, resulting in coloring. Therefore, Tg is preferably 250 ° C. or lower.

  The stretching step may be carried out by known heat setting conditions, cooling, and relaxation treatment, and may be appropriately adjusted so as to have the characteristics required for the target retardation film.

  The stretching is preferably performed under a uniform temperature distribution controlled in the width direction. The temperature is preferably within ± 2 ° C, more preferably within ± 1 ° C, and particularly preferably within ± 0.5 ° C.

  Prior to winding, the ends may be slit and cut to the width of the product, and knurling (embossing) may be applied to both ends to prevent sticking or scratching during winding. The knurling method can process a metal ring having an uneven pattern on its side surface by heating or pressing.

  In addition, since the film has deform | transformed and cannot use as a product normally, the holding | grip part of the clip of both ends of a film is cut out and reused.

  In the present invention, the draw ratio is at least 1% to 250%, more preferably 2% to 200%, and still more preferably 3% to 150%. Although it may be stretched evenly in the vertical and horizontal directions, it is more preferable to stretch one of the stretch ratios more than the other and stretch the same.

  Either length (MD) or width (TD) may be increased, but the smaller draw ratio is preferably 0% to 30%, more preferably 0% to 25%, and still more preferably 0% to 20%. %. The larger draw ratio is 1% to 250%, more preferably 10% to 200%, and still more preferably 30% to 150%.

Stretch ratio (%) = 100 × {(Length after stretching) − (Length before stretching)} / (Length before stretching)
These longitudinal stretching and lateral stretching may be performed independently (uniaxial stretching) or may be performed in combination (biaxial stretching). In the case of biaxial stretching, it may be carried out in the longitudinal and transverse sequential manners (sequential stretching) or simultaneously (simultaneous stretching).

  Following such stretching, it is preferable to relax 0% to 10% in the longitudinal or transverse direction. Furthermore, it is also preferable to heat-fix at 150-250 degreeC for 1 second-3 minutes following extending | stretching.

  Here, Ro indicates in-plane retardation, the difference between the refractive index in the in-plane film forming direction MD and the refractive index in the width direction TD is multiplied by the thickness, and Rt indicates the thickness direction retardation. The difference between the in-plane refractive index (average of the film forming direction MD and the width direction TD) and the refractive index in the thickness direction is multiplied by the thickness.

  Stretching can be performed sequentially or simultaneously with respect to, for example, the film forming direction and the width direction of the film. At this time, if the stretching ratio in at least one direction is too small, a sufficient phase difference cannot be obtained, and if it is too large, stretching becomes difficult and film breakage may occur.

  Stretching in biaxial directions perpendicular to each other is an effective method for bringing the refractive indexes nx, ny, and nz of the film within a predetermined range.

  Here, nx is the refractive index in the film MD direction, ny is the refractive index in the TD direction, and nz is the refractive index in the thickness direction.

  For example, when stretching in the film forming direction, if the shrinkage in the width direction is too large, the value of nz becomes too large. In this case, the width shrinkage of the film can be suppressed or improved by stretching in the width direction. When stretching in the width direction, the refractive index may be distributed in the width direction.

  This distribution may appear when the tenter method is used, and by stretching the film in the width direction, a shrinkage force is generated in the center of the film, and the phenomenon is caused by the end being fixed, It is thought to be a so-called Boeing phenomenon.

  Even in this case, by stretching in the film forming direction, the bowing phenomenon can be suppressed, and the width direction phase or cloth can be reduced.

  By stretching in biaxial directions perpendicular to each other, film thickness fluctuations of the obtained film can be reduced. If the film thickness variation is too large, the phase difference becomes uneven, and unevenness such as coloring may be a problem when used in a liquid crystal display.

  The film thickness variation of the cellulose ester film of the present invention is preferably in the range of ± 3%, and more preferably ± 1%.

  After stretching, after slitting the end of the film to a product width with a slitter, the film is subjected to knurling (embossing) on both ends of the film by a knurling device consisting of an embossing ring and a back roll, and a winder By taking up with, it prevents the cellulose ester film (original winding) from sticking and the generation of scratches.

(Formation of functional layer)
In producing the cellulose ester film of the present invention, before and / or after stretching, a transparent conductive layer, a hard coat layer, an antireflection layer, a slippery layer, an easy adhesion layer, an antiglare layer, a barrier layer, an optical compensation layer, etc. A functional layer may be applied.

In particular, it is preferable to provide at least one layer selected from a transparent conductive layer, a hard coat layer, an antireflection layer, an easy adhesion layer, an antiglare layer, and an optical compensation layer. At this time, each and surface treatment such as corona discharge treatment, plasma treatment, and chemical treatment can be performed as necessary.
<Back layer>
The back layer of the present invention refers to a layer made of a resin having a film-forming ability provided on the surface opposite to the cellulose ester film with respect to the optically anisotropic layer.

The back layer of the present invention comprises a known thermoplastic resin having a film-forming ability, a thermosetting resin, other reactive resins, a hydrophilic binder and a mixture thereof, and an actinic radiation curable resin. It can be formed by coating.
(Coating of known resin with film-forming ability)
Examples of the thermoplastic resin include vinyl polymers or copolymers, acrylic polymers or copolymers, cellulose derivatives, acetals, polyurethane resins, polyester resins, polyether resins, polyamide resins, rubber resins, silicones. -Based resins, fluorine-based resins, and the like, and cellulose derivatives such as diacetylcellulose are particularly preferable.

  Examples of thermosetting resins and other reactive resins include phenol resins, epoxy resins, polyurethane curable resins, urea resins, alkyd resins, and silicone curable resins.

  Moreover, as a hydrophilic binder, a water-soluble polymer, a cellulose ether, a latex polymer, water-soluble polyester, and a mixture thereof can be used, for example.

  Examples of the water-soluble polymer include gelatin, gelatin derivatives, polyvinyl alcohol, acrylic acid copolymers, and maleic anhydride copolymers. Examples of the cellulose ether include carboxymethyl cellulose and hydroxyethyl cellulose. Examples of latex polymers include latexes such as vinyl chloride copolymers, vinylidene chloride copolymers, acrylic ester copolymers, polyester copolymers, vinyl acetate copolymers, and butadiene copolymers. It is done.

  The binder may be hardened. Examples of hardeners that can be used include aldehyde compounds, ketone compounds, compounds having reactive halogens, compounds having reactive olefins, N-methylol compounds, isocyanates, aziridine compounds, acids Examples include derivatives, epoxy compounds, and halogen carboxaldehydes. Moreover, an inorganic type hardener can also be used and a carboxyl group active type hardener etc. can also be mentioned.

  The hardener is usually used in an amount of 0.01 to 30% by mass, preferably 0.05 to 20% by mass, based on the binder.

  In order to adjust the elastic modulus of the back layer, a plasticizer or inorganic particles can be added.

  Although it does not specifically limit as a plasticizer, For example, a dioctyl phthalic acid (DOP), a dibutyl phthalic acid (DBP), a triphenyl phosphate (TPP), a tricresyl phosphate (TCP) etc. are used preferably. These can be used alone or in combination.

Although it does not specifically limit as an inorganic particle, For example, a metal oxide is used preferably. Examples of the metal oxide include aluminum oxide (Al ₂ O ₃ ), silicon dioxide (SiO ₂₎ , tin oxide (SnO ₂₎ , vanadium pentoxide (V ₂ O ₅ ), iron oxide (Fe ₂ O ₃₎ , chromium oxide ( Cr ₂ O ₃ ), titanium dioxide (Ti ₂ O ₃ ), indium oxide (In ₂ O ₃₎ , or a composite oxide thereof.

  A lubricant may be added to impart lubricity. The lubricant may be applied as an overcoat layer outside the outermost layer without a binder.

  The method of applying the lubricant without a binder is not particularly limited, but there are, for example, a method of applying the lubricant by dissolving it with a solvent, a method of emulsifying the lubricant and applying a dispersion thereof. is there.

  The method of incorporating the lubricant into the back layer is not particularly limited. For example, a method in which both the binder and the lubricant are dissolved in a solvent that is dissolved and then applied together with the binder, or as described in JP-A-7-270983. There is a method in which a suitable wax is dispersed in a solvent and applied in a binder.

  The lubricant is not particularly limited, and examples thereof include silicone oils such as polysiloxane, fine powders such as polyethylene and polytetrafluoroethylene, higher fatty acids, higher fatty acid esters, higher fatty acid derivatives, and fluorocarbons. These can be used alone or in combination.

As a coating method, for example, a known method described in JP-A-10-319536 can be used.
(Coating of actinic radiation curable resin)
The layer obtained by curing the actinic radiation curable resin in the present invention is called a so-called hard coat layer, and is preferably a resin layer formed by polymerizing a component containing an ethylenically unsaturated monomer.

  Here, the actinic radiation curable resin layer refers to a layer mainly composed of a resin that is cured through a crosslinking reaction or the like by irradiation with actinic rays such as an electron beam in addition to ultraviolet rays.

  Typical examples of the actinic radiation curable resin include an ultraviolet curable resin and an electron beam curable resin, but a resin that is cured by irradiation with an actinic ray other than ultraviolet rays or an electron beam may be used.

  Examples of the ultraviolet curable resin include an ultraviolet curable acrylic urethane resin, an ultraviolet curable polyester acrylate resin, an ultraviolet curable epoxy acrylate resin, an ultraviolet curable polyol acrylate resin, and an ultraviolet curable epoxy resin. be able to.

  In general, UV-curable acrylic urethane resins are obtained by reacting polyester polyol with an isocyanate monomer or a prepolymer, and further adding 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate (hereinafter referred to as acrylate, methacrylate). Can be easily obtained by reacting an acrylate monomer having a hydroxyl group such as 2-hydroxypropyl acrylate (see, for example, JP-A-59-151110).

  The UV curable polyester acrylate resin can be easily obtained by reacting a polyester polyol with a 2-hydroxyethyl acrylate or 2-hydroxy acrylate monomer (see, for example, JP-A-59-151112). .

  As polyester acrylates, EBECRYL450, 657, 800, 811, 1830, 845, 884 (manufactured by Daicel-Cytech), Aronix M-6100, M-6200, M-6250, M-7100, M-8030, M -8100 (manufactured by Toagosei Co., Ltd.), Hitaroid (manufactured by Hitachi Chemical Co., Ltd.), Laromar LR8800, LR8907, LR8981, LR9004, PE9024V, PE9032V (manufactured by BASF Corp.) and the like can be obtained as commercial products. .

  Specific examples of ultraviolet curable epoxy acrylate resins include those obtained by reacting epoxy acrylate with an oligomer, a reactive diluent and a photoreaction initiator added thereto (for example, JP-A-1- No. 105738).

  As the photoinitiator, one or more kinds selected from benzoin derivatives, oxime ketone derivatives, benzophenone derivatives, thioxanthone derivatives and the like can be selected and used.

  Specific examples of ultraviolet curable polyol acrylate resins include trimethylolpropane triacrylate, ditrimethylolpropane tetraacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, alkyl-modified dipentaerythritol pentaacrylate. Etc.

  These resins are usually used together with known photosensitizers. Moreover, the said photoinitiator can also be used as a photosensitizer.

  Specific examples include acetophenone, benzophenone, hydroxybenzophenone, Michler's ketone, α-amyloxime ester, thioxanthone, and the like.

  In addition, when using an epoxy acrylate photoreactive agent, a sensitizer such as n-butylamine, triethylamine, tri-n-butylphosphine can be used. The photoreaction initiator or photosensitizer contained in the ultraviolet curable resin composition excluding the solvent component that volatilizes after coating and drying can be added in an amount of usually 1 to 10% by mass of the composition, and 2.5 to 6 It is preferable that it is mass%.

  Examples of the resin monomer include common monomers such as methyl acrylate, ethyl acrylate, butyl acrylate, vinyl acetate, benzyl acrylate, cyclohexyl acrylate, and styrene as monomers having one unsaturated double bond.

  In addition, monomers having two or more unsaturated double bonds include ethylene glycol diacrylate, propylene glycol diacrylate, divinylbenzene, 1,4-cyclohexane diacrylate, 1,4-cyclohexyldimethyl adiacrylate, and the above-mentioned trimethylolpropane. Examples thereof include triacrylate and pentaerythritol tetraacryl ester.

  For example, as an ultraviolet curing resin, Adekaoptomer KR / BY series: KR-400, KR-410, KR-550, KR-566, KR-567, BY-320B (above, manufactured by Asahi Denka Kogyo Co., Ltd.) Or KOHEI HARD A-101-KK, A-101-WS, C-302, C-401-N, C-501, M-101, M-102, T-102, D-102, NS-101, FT -102Q8, MAG-1-P20, AG-106, M-101-C (manufactured by Guangei Chemical Co., Ltd.), or Seika Beam PHC2210 (S), PHC X-9 (K-3), PHC2213, DP- 10, DP-20, DP-30, P1000, P1100, P1200, P1300, P1400, P1500, P1600, SCR900 (above, large Manufactured by Seika Kogyo Co., Ltd.), or KRM7033, KRM7039, KRM7130, KRM7131, UVECRYL29201, UVECRYL29202 (above, Daicel UCB Corporation), or RC-5015, RC-5016, RC-5020, RC-5031, RC- 5100, RC-5102, RC-5120, RC-5122, RC-5152, RC-5171, RC-5180, RC-5181 (manufactured by Dainippon Ink & Chemicals, Inc.) or Aulex No. 340 clear (manufactured by China Paint Co., Ltd.), or Sun Rad H-601 (manufactured by Sanyo Chemical Industries, Ltd.), SP-1509, SP-1507 (manufactured by Showa Polymer Co., Ltd.), or RCC-15C (Grace Japan Co., Ltd.) (Manufactured by company), Aronix M-6100, M-8030, M-8060 (above, manufactured by Toagosei Co., Ltd.) or other commercially available products.

  The ultraviolet curable resin layer can be applied by a known method.

  As the solvent for coating the ultraviolet curable resin layer, for example, it can be appropriately selected from hydrocarbons, alcohols, ketones, esters, glycol ethers, and other solvents, or a mixture thereof can be used. .

  Preferably, propylene glycol mono (alkyl group having 1 to 4 carbon atoms) alkyl ether, preferably propylene glycol mono (alkyl group having 1 to 4 carbon atoms) alkyl ether ester is 5% by mass or more, more preferably 5 to 80% by mass. The solvent contained above is used.

  As a light source for forming a cured film layer by photocuring reaction of an ultraviolet curable resin, any light source that generates ultraviolet rays can be used. For example, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a carbon arc lamp, a metal halide lamp, a xenon lamp, or the like can be used.

The irradiation conditions vary depending on individual lamps, but the amount of light irradiated may be any degree 20~10000mJ / cm ^2, preferably from 50~2000mJ / cm ^2. It can be used by using a sensitizer having an absorption maximum in the near ultraviolet region to the visible light region.

  The UV curable resin composition is applied and dried and then irradiated with UV light from a light source. The irradiation time is preferably 0.5 seconds to 5 minutes, and 3 seconds to 2 in view of curing efficiency and work efficiency of the UV curable resin. Minutes are more preferred.

  It is preferable to add inorganic or organic fine particles to the cured film layer thus obtained in order to prevent blocking and to improve scratch resistance.

  Examples of the inorganic fine particles include silicon oxide, titanium oxide, aluminum oxide, tin oxide, zinc oxide, calcium carbonate, barium sulfate, talc, kaolin, calcium sulfate, and the like, and examples of the organic fine particles include polymethacrylic acid. Methyl acrylate resin powder, acrylic styrene resin powder, polymethyl methacrylate resin powder, silicone resin powder, polystyrene resin powder, polycarbonate resin powder, benzoguanamine resin powder, melamine resin powder, polyolefin resin powder, polyester resin powder Polyamide-based resin powder, polyimide-based resin powder, or polyfluorinated ethylene-based resin powder, and the like can be added to the ultraviolet curable resin composition.

  The average particle diameter of these fine particle powders is preferably 0.005 μm to 1 μm, and particularly preferably 0.01 to 0.1 μm.

  The proportion of the ultraviolet curable resin composition and the fine particle powder is desirably 0.1 to 30 parts by mass, preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of the resin composition.

  The layer obtained by curing the ultraviolet curable resin thus formed is a hard coat layer having a center line average roughness Ra of 1 to 50 nm as defined in JIS B 0601. An antiglare layer of a degree may be used.

  As a method for applying the hard coat layer to the substrate film, a known method such as a gravure coater, spinner coater, wire bar coater, roll coater, reverse coater, extrusion coater, air doctor coater, or the like can be used.

  The liquid film thickness (also referred to as wet film thickness) at the time of application is about 1 to 100 μm, preferably 0.1 to 30 μm, and more preferably 0.5 to 15 μm. The dry film thickness of the hard coat layer is preferably 1 to 20 μm.

The elastic modulus of the diacetylcellulose layer as the back layer of the present invention can achieve 3.0 to 4.0 kN / mm ² , and the hard coat layer can achieve 3.0 to 6.5 kN / mm ^2. Can do.
<Optically anisotropic layer in which rod-like liquid crystal is vertically aligned and fixed in alignment>
The optically anisotropic layer of the present invention preferably has the following characteristics.

0 ≦ Ro ≦ 10
−500 ≦ Rt ≦ −100
The optically anisotropic layer of the present invention is obtained by applying a liquid crystal material or a liquid crystal solution directly on the cellulose ester film or on an intermediate layer, drying and heat treatment (also referred to as orientation treatment), and then curing the liquid crystal by ultraviolet curing or thermal polymerization. It is characterized by having a retardation layer made of rod-like liquid crystals that are fixed in alignment and aligned in the vertical direction.

  Here, “orienting in the vertical direction” means that the rod-like liquid crystal is in the range of 70 to 90 ° (the vertical direction is 90 °) with respect to the film surface serving as the support.

  The rod-like liquid crystal may be oriented obliquely or the orientation angle may be gradually changed. Preferably it is the range of 80-90 degrees.

  The retardation layer of the present invention is a retardation layer made of rod-like liquid crystal aligned in the vertical direction in which Ro is in the range of 0 to 10 nm and Rt is in the range of −500 to −100 nm. Further, Ro is more preferably in the range of 0 to 5 nm. The phase difference of the phase difference of the layer on which the liquid crystal alignment is fixed on these supports can be measured using AxoScan manufactured by Opto Science Co., Ltd.

  When forming a retardation layer by aligning rod-shaped liquid crystals, an alignment film coated with a vertical alignment agent that aligns the so-called liquid crystal material in the vertical direction is used, and the liquid crystal material is vertically aligned and then fixed. be able to.

  When the liquid crystal material itself is aligned in the vertical direction at the air interface, the alignment regulating force extends to the interface opposite to the air interface, and the alignment film is not particularly necessary, and this is also preferable from the viewpoint of simplifying the configuration. preferable.

  As a specific method for vertically aligning the liquid crystal material, an alignment film composed of a cross-linked product of a block polymer composition containing a (meth) acrylic block polymer described in JP-A-2005-148473 and the like is used. Known methods such as a method of using, a method of using a vertical alignment film described in JP 2005-265889 A, and a method of using an air interface vertical alignment agent can be used.

  In order to make the retardation layer in the above range, it is preferable to control the orientation of the rod-like liquid crystal layer, the film thickness control, the temperature during UV curing, the tilt angle control, and the control of the pretilt angle at the support / air interface.

  The liquid crystal layer is formed by curing a liquid crystal material capable of forming a liquid crystal phase at a predetermined temperature with a predetermined liquid crystal regularity. The upper limit of the temperature showing the liquid crystal phase is not particularly limited as long as the cellulose ester film of the base material is not damaged.

  Specifically, a temperature of 120 ° C. or lower is preferable from the viewpoint of easy control of process temperature and maintenance of dimensional accuracy, and a liquid crystal material that becomes a liquid crystal phase at a temperature of 100 ° C. or lower is preferably used. On the other hand, the lower limit of the temperature showing the liquid crystal phase can be said to be a temperature at which the liquid crystal material can maintain the alignment state when used as a polarizing plate.

  As the liquid crystal material used for the retardation layer of the present invention, a polymerizable liquid crystal material is preferably used. The polymerizable liquid crystal material can be used by being polymerized by irradiating with predetermined actinic radiation. In the polymerized state, the vertical alignment state is fixed.

  As the polymerizable liquid crystal material, any of a polymerizable liquid crystal monomer, a polymerizable liquid crystal oligomer, and a polymerizable liquid crystal polymer can be used, and they can also be mixed with each other.

  Of the above, a polymerizable liquid crystal monomer is preferably used as the polymerizable liquid crystal material because of its high sensitivity during alignment and easy vertical alignment.

  Specific examples of the polymerizable liquid crystal monomer include a rod-like liquid crystal compound (I) represented by the following general formula (1) and a rod-like liquid crystal compound (II) represented by the following general formula (2). be able to. As the compound (I), two or more compounds included in the general formula (1) can be mixed and used. Similarly, the compound (II) is included in the general formula (2). Two or more kinds of compounds may be mixed and used. In addition, one or more compounds (I) and one or more compounds (II) may be mixed and used.

  In the general formula (1) representing the compound (I), R1 and R2 each represent hydrogen or a methyl group, but it is preferable that both R1 and R2 are hydrogen because of the wide temperature range showing the liquid crystal phase.

  X may be hydrogen, chlorine, bromine, iodine, an alkyl group having 1 to 4 carbon atoms, a methoxy group, a cyano group, or a nitro group, but is preferably chlorine or a methyl group.

  Moreover, a and b which show the chain length of the alkylene group which is a spacer with the (meth) acryloyloxy group of both ends of the molecular chain of a compound (I), and an aromatic ring are respectively arbitrary integers in the range of 2-12. Although it can take, it is preferable that it is the range of 4-10, and it is more preferable that it is the range of 6-9.

  In addition to the above, in the present invention, conventionally known materials can be appropriately selected and used as the polymerizable liquid crystal oligomer and the polymerizable liquid crystal polymer.

  For example, as a polymerizable rod-like liquid crystalline compound, Makromol. Chem. 190, 2255 (1989), Advanced Materials 5, 107 (1993), US Pat. No. 4,683,327, US Pat. No. 5,622,648, US Pat. No. 5,770,107, International Publication WO95 / 22586. No. 95/24455, No. 97/00600, No. 98/23580, No. 98/52905, JP-A-1-272551, No. 6-16616, and No. 7-110469. 11-80081, JP 2001-328773, JP 2004-240188, JP 2005-99236, JP 2005-99237, JP 2005-121827, JP It is possible to use the compounds described in 2002-30042 wear.

  As commercially available compounds, UCL-018 (Dainippon Ink Chemical Co., Ltd.), Palio Color LC242 (BASF Co., Ltd.), etc. can be used.

  In the present invention, a photopolymerization initiator is used as required in addition to the polymerizable liquid crystal material. When polymerizing a polymerizable liquid crystal material by electron beam irradiation, a photopolymerization initiator may not be necessary. However, in the case of curing by, for example, ultraviolet (UV) irradiation, which is generally used, photopolymerization is usually performed. An initiator is used to promote polymerization.

  Photopolymerization initiators include benzyl (also called bibenzoyl), benzoin isobutyl ether, benzoin isopropyl ether, benzophenone, benzoyl benzoic acid, methyl benzoyl benzoate, 4-benzoyl-4'-methyldiphenyl sulfide, benzyl methyl ketal, dimethylamino Methylbenzoate, 2-n-butoxyethyl-4-dimethylaminobenzoate, isoamyl p-dimethylaminobenzoate, 3,3′-dimethyl-4-methoxybenzophenone, methylobenzoylformate, 2-methyl-1- (4 -(Methylthio) phenyl) -2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butan-1-one, 1- (4-dodecylphenyl) -2- Droxy-2-methylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1- (4-isopropylphenyl) -2-hydroxy-2- Examples include methylpropan-1-one, 2-chlorothioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, or 1-chloro-4-propoxythioxanthone. it can.

  In general, the addition amount of the photopolymerization initiator is preferably 0.01% to 20%, more preferably 0.1% to 10%, and still more preferably 0.5% to 5%. Can be added to the polymerizable liquid crystal material of the present invention.

  In addition to the photopolymerization initiator, a sensitizer can be added as long as the object of the present invention is not impaired.

  The film thickness of the liquid crystal layer in the present invention is preferably in the range of 0.1 μm to 10 μm, and more preferably in the range of 0.2 to 5 μm.

  A polymerizable liquid crystal material is prepared by using a composition for forming a liquid crystal layer by blending a photopolymerization initiator, a sensitizer, etc., if necessary, and coating on a substrate to form a liquid crystal layer forming layer. To do.

  As a method of forming a layer in which the orientation of liquid crystal is fixed, for example, a method in which a dry film or the like is formed in advance and a layer in which the orientation of liquid crystal is fixed is laminated on a substrate, or a liquid crystal composition is dissolved. Alternatively, it is possible to use a method of melting and coating on a substrate, but in the present invention, a liquid crystal composition is added with a solvent and a coating composition in which other components are dissolved is used. It is preferable to form a layer in which the orientation of the liquid crystal is fixed by coating on the substrate and removing the solvent. This is simple in terms of process as compared with other methods.

  The solvent is not particularly limited as long as it is a solvent capable of dissolving the above-described polymerizable liquid crystal material and the like and does not deteriorate the properties of the transparent resin film. Specifically, benzene, Hydrocarbons such as toluene, xylene, n-butylbenzene, diethylbenzene, tetralin; ethers such as methoxybenzene, 1,2-dimethoxybenzene, diethylene glycol dimethyl ether; acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, or 2,4- Ketones such as pentanedione; ethyl acetate, ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, or γ-butyrolactone Amides solvents such as 2-pyrrolidone, N-methyl-2-pyrrolidone, dimethylformamide or dimethylacetamide; chloroform, dichloromethane, carbon tetrachloride, dichloroethane, tetrachloroethane, tritrichloroethylene, tetrachloroethylene, chlorobenzene, or orthodichlorobenzene Halogen solvents such as t-butyl alcohol, diacetone alcohol, glycerin, monoacetin, ethylene glycol, triethylene glycol, hexylene glycol, ethylene glycol monomethyl ether, ethyl cellosolve, or butyl cellosolve; phenols, One or more of phenols such as parachlorophenol can be used.

  If only a single type of solvent is used, the solubility of the polymerizable liquid crystal material or the like may be insufficient, or the substrate may be eroded as described above. However, this inconvenience can be avoided by using a mixture of two or more solvents.

  Of the above-mentioned solvents, preferred as a single solvent are a hydrocarbon solvent and a glycol monoether acetate solvent, and a preferred mixed solvent is a mixed system of ethers or ketones and glycols. It is.

  The concentration of the solution depends on the solubility of the polymerizable liquid crystal material or the like and the film thickness of the liquid crystal layer to be produced, but cannot be defined unconditionally, but is usually preferably 1% to 60%, more preferably 3% to It is adjusted within the range of 40%.

  Compounds other than those described above can be added to the composition for forming a liquid crystal layer used in the present invention within a range not impairing the object of the present invention.

  Examples of compounds that can be added include polyester (meth) acrylate obtained by reacting (meth) acrylic acid with a polyester prepolymer obtained by condensing polyhydric alcohol and monobasic acid or polybasic acid; A polyurethane (meth) acrylate obtained by reacting a compound having two isocyanate groups with each other and then reacting the reaction product with (meth) acrylic acid; bisphenol A type epoxy resin, bisphenol F type epoxy resin, novolak Type epoxy resin, polycarboxylic acid polyglycidyl ester, polyol polyglycidyl ether, aliphatic or cycloaliphatic epoxy resin, amine epoxy resin, triphenolmethane type epoxy resin, dihydroxybenzene type epoxy resin and the like (meth) Ak A photopolymerizable compound such as epoxy (meth) acrylate obtained by reacting phosphoric acid, a photopolymerizable liquid crystal compound having an acrylic group or a methacryl group, an onium salt described in JP-A-2007-45993, and a fluorine compound. Acrylate polymers and the like.

  The amount of these compounds added to the composition for forming a liquid crystal layer of the present invention is selected within a range that does not impair the purpose of the present invention, and is generally 40% or less of the composition for forming a liquid crystal layer of the present invention. Preferably, it is 20% or less.

  Addition of these compounds improves the curability of the liquid crystal material in the present invention, increases the mechanical strength of the resulting liquid crystal layer, and improves its stability.

  In addition, a surfactant or the like can be added to the composition for forming a liquid crystal layer containing a solvent in order to facilitate coating.

  Examples of surfactants that can be added include cationic surfactants such as imidazoline, quaternary ammonium salts, alkylamine oxides and polyamine derivatives; polyoxyethylene-polyoxypropylene condensates, primary or secondary Alcohol ethoxylates, alkylphenol ethoxylates, polyethylene glycol and esters thereof, sodium lauryl sulfate, ammonium lauryl sulfate, lauryl sulfate amines, alkyl-substituted aromatic sulfonates, alkyl phosphates, aliphatic or aromatic sulfonic acid formalin condensates, etc. Anionic surfactants; amphoteric surfactants such as laurylamidopropylbetaine and laurylaminoacetic acid betaine; nonionics such as polyethylene glycol fatty acid esters and polyoxyethylene alkylamine Surfactant: Perfluoroalkyl sulfonate, perfluoroalkyl carboxylate, perfluoroalkyl ethylene oxide adduct, perfluoroalkyl trimethyl ammonium salt, perfluoroalkyl group / hydrophilic group-containing oligomer, perfluoroalkyl / lipophilic group Fluorosurfactants such as containing oligomer perfluoroalkyl group-containing urethanes.

  The amount of surfactant added depends on the type of surfactant, the type of liquid crystal material, the type of solvent, and the type of alignment film on which the solution is applied. 10 ppm to 10% is preferable, more preferably 100 ppm to 5%, and still more preferably 0.1 to 1%.

  As a method for coating the composition for forming a liquid crystal layer, a spin coating method, a roll coating method, a printing method, a dip pulling method, a die coating method, a casting method, a bar coating method, a blade coating method, a spray coating method, a gravure coating method , Reverse coating method or extrusion coating method.

  The method for removing the solvent after coating the composition for forming a liquid crystal layer is performed, for example, by air drying, heat removal, or removal under reduced pressure, or a combination thereof. By removing the solvent, a layer in which the alignment of the liquid crystal is fixed is formed.

  In the step of curing the polymerizable liquid crystal material, energy for curing the polymerizable liquid crystal material is given, and thermal energy may be used, but it is usually performed by irradiation with ionizing radiation capable of causing polymerization.

  If necessary, a polymerization initiator may be contained in the polymerizable liquid crystal material. The ionizing radiation is not particularly limited as long as it is a radiation capable of polymerizing the polymerizable liquid crystal material, but usually ultraviolet light or visible light is used from the viewpoint of the ease of the apparatus, and the wavelength. Is preferably from 150 to 500 nm, more preferably from 250 to 450 nm, and even more preferably from 300 to 400 nm.

  In the present invention, a method of performing radical polymerization by irradiating ultraviolet rays (UV) as actinic radiation and generating radicals from the polymerization initiator with ultraviolet rays is preferable. Since the method using UV as the actinic radiation is an already established technique, it can be easily applied to the present invention including the polymerization initiator to be used.

  As a light source for irradiating ultraviolet rays, a low-pressure mercury lamp (sterilization lamp, fluorescent chemical lamp, black light), a high-pressure discharge lamp (high-pressure mercury lamp, metal halide lamp), or a short arc discharge lamp (ultra-high-pressure mercury lamp, xenon) Lamp, mercury xenon lamp) and the like.

  In particular, the use of metal halide lamps, xenon lamps, high-pressure mercury lamps, etc. is recommended. The irradiation intensity may be appropriately adjusted depending on the composition of the polymerizable liquid crystal material used for forming the layer in which the alignment of the liquid crystal is fixed and the amount of the photopolymerization initiator.

  The alignment fixing step by irradiation with actinic radiation may be performed at the processing temperature in the step of forming the liquid crystal layer forming layer described above, that is, the temperature condition in which the polymerizable liquid crystal material becomes a liquid crystal phase, It may be performed at a lower temperature.

<Intermediate layer>
An intermediate layer can be provided between the optically anisotropic layer in which the cellulose ester film of the present invention and the rod-like liquid crystal are vertically aligned to fix the alignment.

  The intermediate layer of the present invention is made of a transparent resin. The transparent resin is preferably a binder polymer having a saturated hydrocarbon chain or a polyether chain as a main chain, and more preferably a binder polymer having a saturated hydrocarbon chain as a main chain.

  Particularly preferred is a resin that is cured through a crosslinking reaction or the like by irradiation with active rays such as ultraviolet rays or electron beams, or a mixed composition of a crosslinking agent and a resin having a reactive site.

  Examples of the curable resin include UV curable urethane acrylate resins, UV curable polyester acrylate resins, UV curable epoxy acrylate resins, UV curable polyol acrylate resins, and UV curable epoxy resins. A type acrylate resin is preferably used.

  The UV curable urethane acrylate resin generally includes a product obtained by reacting a polyester polyol with an isocyanate monomer or a prepolymer, and further includes 2-hydroxyethyl acrylate and 2-hydroxyethyl methacrylate (hereinafter, acrylate includes methacrylate). It can be easily obtained by reacting an acrylate monomer having a hydroxyl group such as 2-hydroxypropyl acrylate.

  For example, those described in JP 59-151110 A can be used. For example, a mixture of 100 parts of purple light UV-7510B (manufactured by Nippon Synthetic Chemical Co., Ltd.), Unidic 17-806 (manufactured by Dainippon Ink Co., Ltd.) and 1 part of coronate L (manufactured by Nippon Polyurethane Co., Ltd.) Preferably used.

  Examples of UV curable polyester acrylate resins include those which are easily formed when 2-hydroxyethyl acrylate and 2-hydroxy acrylate monomers are generally reacted with polyester polyols. JP-A-59-151112 Those described in the publication can be used.

  Specific examples of the ultraviolet curable epoxy acrylate resin include an epoxy acrylate as an oligomer, a reactive diluent and a photopolymerization initiator added thereto, and reacted to form an oligomer. Those described in Japanese Patent No. 105738 can be used.

  Specific examples of UV curable polyol acrylate resins include trimethylolpropane triacrylate, ditrimethylolpropane tetraacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, alkyl-modified dipentaerythritol pentaacrylate, etc. Can be mentioned.

  Specific examples of photopolymerization initiators for these curable resins include benzoin and derivatives thereof, acetophenone, benzophenone, hydroxybenzophenone, Michler's ketone, α-amyloxime ester, thioxanthone, and derivatives thereof. You may use with a photosensitizer.

  In addition, when using an epoxy acrylate photopolymerization initiator, a sensitizer such as n-butylamine, triethylamine, tri-n-butylphosphine can be used.

  The photopolymerization initiator or photosensitizer used in the curable resin composition is 0.1 to 25 parts by mass, preferably 1 to 15 parts by mass with respect to 100 parts by mass of the composition.

  Examples of the mixed composition of the crosslinking agent and the resin having a reactive site according to the present invention include polyvinyl alcohol and glyoxal, gelatin and glyoxal.

  Further, the intermediate layer may contain a fluorine-acrylic copolymer resin. The fluorine-acrylic copolymer resin is a copolymer resin composed of a fluorine monomer and an acrylic monomer, and a block copolymer composed of a fluorine monomer segment and an acrylic monomer segment is particularly preferable.

  The intermediate layer of the present invention may be two or more layers.

<Method for producing intermediate layer>
For the intermediate layer, a coating composition for forming the intermediate layer containing the retardation increasing agent of the present invention is applied using a known method such as a gravure coater, dip coater, reverse coater, wire bar coater, die coater, and ink jet method. It is preferable that after coating on a support, it is dried by heating and UV-cured.

  The coating amount is suitably 0.1 to 40 μm, preferably 0.5 to 30 μm, as the wet film thickness.

  Moreover, as a dry film thickness, it is an average film thickness of 0.01-1 micrometer, Preferably it is 0.02-0.7 micrometer.

  As the light source for the UV curing treatment, any light source that generates ultraviolet rays can be used without limitation. For example, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a carbon arc lamp, a metal halide lamp, a xenon lamp, or the like can be used.

Irradiation conditions vary depending on each lamp, but the irradiation amount of active rays is usually 5 to 500 mJ / cm ² , preferably 5 to 150 mJ / cm ² .

  Moreover, when irradiating actinic radiation, it is preferable to carry out while applying tension | tensile_strength in the conveyance direction of a film, More preferably, it is performing applying tension | tensile_strength also in the width direction. The tension to be applied is preferably 30 to 300 N / m.

  The method for applying tension is not particularly limited, and tension may be applied in the transport direction on the back roll, or tension may be applied in the width direction or biaxial direction by a tenter. This makes it possible to obtain a film having further excellent flatness.

  The coating composition for forming the intermediate layer may contain a solvent. Examples of the organic solvent contained in the coating composition include hydrogen (toluene, xylene), alcohols (methanol, ethanol, isopropanol, butanol, cyclohexanol), and ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone). , Esters (methyl acetate, ethyl acetate, methyl lactate), glycol ethers, and other organic solvents may be appropriately selected or mixed for use.

As the organic solvent, propylene glycol monoalkyl ether (1 to 4 carbon atoms of the alkyl group) or propylene glycol monoalkyl ether acetate (1 to 4 carbon atoms of the alkyl group) is preferable. Moreover, as content of an organic solvent, 5-80 mass% is preferable in a coating composition.
<Polarizing plate>
The polarizing plate of the present invention will be described.

  The polarizing plate can be produced by a general method. The cellulose ester film of the present invention is preferably subjected to alkali saponification treatment, and the treated film is bonded to at least one surface of a polarizer prepared by immersing and stretching in an iodine solution using a completely saponified polyvinyl alcohol aqueous solution. .

  In the case of an optically anisotropic film other than the cellulose ester film, it is preferable to use an acrylic or urethane adhesive.

  The polarizer of the present invention includes a polyvinyl alcohol polarizing film, which is a polyvinyl alcohol film dyed with iodine and a dichroic dye dyed.

  For the polarizer, a polyvinyl alcohol aqueous solution is formed into a film and dyed by uniaxial stretching or dyed or uniaxially stretched and then preferably subjected to a durability treatment with a boron compound.

  On the surface of the polarizer, one side of the cellulose ester film of the present invention is bonded to form a polarizing plate. It is preferably bonded with an aqueous adhesive mainly composed of completely saponified polyvinyl alcohol or the like.

  The long cellulose ester film produced by the melt casting film-forming method according to the present invention can be bonded with a long polarizer (polarizing film) by subjecting it to alkali saponification treatment. The productive effect is obtained with a long length of 1, and the longer the length is 1500 m, 2500 m, and 5000 m, the higher the productive effect of manufacturing the polarizing plate.

Moreover, since the polarizing plate using the cellulose ester film of this invention is excellent in rework property, the effect that a polarizing plate yield improves can also be acquired.
<Liquid crystal display device>
The polarizing plate containing the cellulose ester film of the present invention can exhibit high display quality as compared with a normal polarizing plate.

  The polarizing plate of the present invention includes an MVA (Multi-domain Vertical Alignment) mode, a PVA (Patterned Vertical Alignment) mode, an OCB (Optical Compensated InP) mode, an OCB (Optical Compensation B) mode, and an OCB (Optical Compensation B) mode. Can be used.

  The liquid crystal display device is applied as a device for colorization and moving image display, and the display quality is improved by the present invention, and the contrast is improved and the resistance of the polarizing plate is improved. .

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
<Synthesis of cellulose ester>
With reference to Example B of JP-A-6-501040, the amounts of propionic acid, butyric acid, and acetic acid are adjusted, and the degree of acetyl group substitution, degree of propionyl group substitution, and degree of butyryl group substitution are as shown in Table 1. Five different cellulose esters were synthesized.

The substitution degree of the obtained cellulose ester was calculated based on ASTM-D817-96.
<Production of Polarizing Plate Protective Film A by Melting Method>
(Synthesis of acrylic polymer X1)
Bulk polymerization was performed by the polymerization method described in JP-A No. 2000-344823. That is, the contents were heated to 70 ° C. while introducing the following methyl acrylate and ruthenocene into a flask equipped with a stirrer, a nitrogen gas inlet tube, a thermometer, an inlet, and a reflux condenser.

  Next, half of the following β-mercaptopropionic acid which had been sufficiently purged with nitrogen gas was added to the flask under stirring. After the addition of β-mercaptopropionic acid, the contents in the stirring flask were maintained at 70 ° C. and polymerization was carried out for 2 hours.

  Further, after adding the other half of the β-mercaptopropionic acid substituted with nitrogen gas, the temperature of the content being stirred was maintained at 70 ° C., and polymerization was carried out for 4 hours. The temperature of the reaction product was returned to room temperature, and 20 parts by mass of a 5% by mass benzoquinone tetrahydrofuran solution was added to the reaction product to stop the polymerization.

  While gradually heating the polymer to 80 ° C. under reduced pressure with an evaporator, the tetrahydrofuran, residual monomer and residual thiol compound were removed to obtain an acrylic polymer X1. The weight average molecular weight Mw was 1000.

Methyl acrylate 100 parts by weight Ruthenocene (metal catalyst) 0.05 parts by weight β-mercaptopropionic acid 12 parts by weight Cellulose ester A dried at 80 ° C. for 6 hours (water content 200 ppm), 100 parts by weight, plasticizer (polyhydric alcohol) Ester plasticizer specific example No. 63) 8 parts by mass, monopet SB (sugar ester compound) 4 parts by mass, ultraviolet absorber LA-31 (manufactured by ADEKA) 1.05 parts by mass, Irganox 1010 (Ciba Japan Co., Ltd.) 0.5 parts by mass, Adeka Stub PEP-36 (ADEKA Co., Ltd.) 0.08 parts by mass, Sumilizer GS (Sumitomo Chemical Co., Ltd.) 0.2 parts by mass, Sea Hoster KEP-30 (Japan) 0.1 parts by weight (made by Catalyst Co., Ltd.) was further dried with mixing in a vacuum nauter mixer at 80 ° C. and 1 Torr for 3 hours. It was.

  The obtained mixture was melt-mixed at 235 ° C. using a twin-screw extruder and pelletized.

  The cellulose ester film was produced by the production apparatus shown in FIG.

  Pellets (water content 50 ppm) were melt extruded from a T die onto a first cooling roll having a surface temperature of 100 ° C. at a melting temperature of 245 ° C. using a single-screw extruder, with an initial film thickness of 128 μm and a width of 1.0 m. A cast film of 35 m / min was obtained.

  At this time, the film was pressed on the first cooling roll with an elastic touch roll having a 2 mm thick metal surface.

  The obtained film was first stretched at 195 ° C. in the film-forming direction at a stretching rate of 1000% / min at 195 ° C. at a stretching speed of 1000% / min by a stretching machine using a roll peripheral speed difference to obtain a protective film 101 having a thickness of 40 μm.

  Next, in the same manner as the cellulose ester film 101 of the present invention, except that the cellulose ester, sugar ester compound amount, plasticizer (type, amount), stretching speed, stretching ratio, and initial film thickness were changed as shown in Table 2. The protective films 102 to 118 and 201 to 203 of the present invention and comparative examples were prepared so as to have the film thicknesses shown in Table 2.

  In addition, "BR85" in the table means Dianal BR85 (manufactured by Mitsubishi Rayon Co., Ltd.).

  In Samples 102 and 106, 10 parts by mass of acrylic polymer X1 was added instead of 10 parts by mass of Monopet SB. Sample 110 was added with 5 parts by mass of monopet SB and acrylic polymer X1 instead of 10 parts by mass of monopet SB.

At this time, in the width direction, after stretching in the film forming direction, a preheating zone, a stretching zone, a holding zone, and a cooling zone (a neutral zone for ensuring thermal insulation between the zones is also provided between the zones). The film was obtained in a stretching zone at 165 ° C. in a stretching zone, then cooled to 30 ° C., released from the clip, and the clip gripping part was cut off.
<Preparation of back layer>
After these corona discharges were applied to these protective films, the following back layer coating solution 1 was applied and dried to provide a back layer 1 having a thickness of 1.0 μm.
(Back layer coating solution 1)
Cellulose diacetate 5g
DOP See Table 1 SiO ₂ particles (particle size 0.02 μm) See Table 1 Acetone 500 ml
500 ml of ethyl acetate
In addition, the following back layer coating solution 2 is filtered through a polypropylene filter having a pore size of 0.4 μm to prepare a coating solution. After the corona discharge is applied to the protective film, it is applied, dried at 90 ° C., and then subjected to ultraviolet rays. The functional film was cured using a lamp with an illuminance of the irradiated part of 100 mW / cm ² and an irradiation amount of 0.1 J / cm ² to form a back layer with a thickness of 10 μm.
(Back layer coating solution 2)
Acrylic monomer: KAYARAD DPHA (dipentaerythritol hexaacrylate, manufactured by Nippon Kayaku Co., Ltd.) 225 parts by mass Irgacure 184 (manufactured by Ciba Japan) 20 parts by mass Propylene glycol monomethyl ether 110 parts by mass Ethyl acetate 110 parts by mass < Production of optically anisotropic layer in which rod-like liquid crystal is vertically aligned and fixed in alignment>
On the surface opposite to the back layer of the protective film coated with the back layer, the following intermediate layer coating solution is applied to the transparent film 100 with a wire bar # 3, dried at 80 ° C. for 30 seconds, and then irradiated with ultraviolet rays of 120 mJ / cm. ² was cured by irradiation for 10 seconds. The film thickness of the intermediate layer after drying was 0.5 μm.

(Interlayer coating solution)
25 parts by mass of polyester acrylate (manufactured by Laromar LR8800 BASF Japan)
Propylene glycol monomethyl ether 290 parts by mass Isopropyl alcohol 685 parts by mass Photopolymerization initiator 0.05 parts by mass (Irgacure 184, manufactured by Ciba Japan Co., Ltd.)
(Anisotropic layer coating solution)
UV-polymerizable liquid crystal material 20 parts by mass (UCL-018 manufactured by Dainippon Ink & Chemicals, Inc.)
Propylene glycol monomethyl ether 80 parts by mass Hindered amine 0.02 parts by mass LS-765 (Sankyo Life Tech Co., Ltd.)
0.10 parts by mass of sensitizer (Kayacure DETX, manufactured by Nippon Kayaku Co., Ltd.)
The following air interface side vertical alignment agent 1 0.01 parts by mass

  This anisotropic layer coating solution was applied on the straight alignment film with a thickness of 8 μm by a die coater. Then, it heated for 2 minutes in a 100 degreeC thermostat, and the rod-shaped liquid crystal compound was orientated.

Next, the coated film was irradiated with UV light of 250 mJ / cm ² at an oxygen concentration of 0.2% and a temperature of 28 ° C. for 10 seconds to cure the polymerizable liquid crystal composition, whereby a retardation film 101 was obtained. The thickness of the anisotropic layer was 1.2 μm.

  The overall retardation film had Ro of 71 nm and Rt of −10 nm. In all the retardation film samples 102 to 119, the thickness of the liquid crystal layer was adjusted so that the total retardation Ro and Rt were as shown in Table 2.

  As a comparative sample 204, a sample according to Example 1 of the present invention was prepared as a comparative sample 204, and the same intermediate layer and anisotropic layer as the sample 101 were coated thereon.

  The retardation film thus obtained was evaluated as follows.

The amount of the solvent contained was 0.01% by mass or less in all samples.
(Elastic modulus)
The specimen was conditioned for 24 hours in an environment of 23 ° C. and 55% RH, and in accordance with the method described in JIS K7127, using Tensilon RTA-100 manufactured by Orientec Co., Ltd. Is a type 1 test piece, and the test speed was measured under the condition of 10 mm / min.

The elastic modulus of the back layer was determined by subtracting the elastic modulus of the cellulose ester film from the whole cellulose ester film after application.
(Evaluation method for uneven orientation)
<Phase difference unevenness>
A retardation film sample was subjected to retardation Ro measurement at 0.5 mm pitch at a measurement spot of 0.5 mm using a birefringence phase difference measuring device AD-175SI manufactured by Saitoh Co., Ltd. The measurement was performed by inclining 40 ° with the in-plane slow axis of the film as the tilt axis.

  In addition, before performing application | coating of a liquid-crystal layer, the phase difference nonuniformity of the cellulose-ester film was measured and it confirmed that there was no nonuniformity in less than 0.080 nm by 0.1 mm space | interval.

  The following was used as a reference for phase difference unevenness.

Interval Retardation difference Evaluation 0.1mm Less than 0.080nm ◎
0.1mm 0.080 or more and less than 0.110nm ○
0.1 mm 0.110 or more and less than 0.150 nm
0.1 mm 0.150 nm or more ×
<Contained solvent amount>
Each sample was placed in a 20 ml sealed glass container, treated under the following headspace heating conditions, and then a calibration curve was prepared and measured for the solvent used in advance by the following gas chromatography. The amount of solvent contained was expressed in parts by mass relative to the total mass of the polarizing plate protective film A.
Equipment: HP 5890SERIESII
Column: J & W DB-WAX (inner diameter 0.32 mm, length 30 m)
Detection: FID
GC temperature rising condition: held at 40 ° C. for 5 minutes, then heated to 80 ° C./min to 100 ° C. Headspace heating condition: 120 ° C. for 20 min
<Production of polarizing plate and liquid crystal display device>
(Alkaline saponification treatment)
The prepared protective films 101 to 126 and the optically anisotropic films A, B, C, D, E, and F were subjected to alkali saponification treatment as described below.

Saponification process 2.5M-NaOH 50 ° C. 90 seconds Washing process Water 30 ° C. 45 seconds Neutralizer 10 parts by mass HCl 30 ° C. 45 seconds Water washing process Water 30 ° C. 45 seconds After saponification treatment, water washing, neutralization, water washing in this order And then dried at 80 ° C.

<Production and bonding of polarizers>
A 120 μm-thick long roll polyvinyl alcohol film was immersed in 100 parts by mass of an aqueous solution containing 1 part by mass of iodine and 4 parts by mass of boric acid, and stretched in the film forming direction 6 times at 50 ° C. to produce a polarizer.

  Next, using a polyvinyl alcohol-based adhesive, display a protective film on one side of the polarizer and an optically anisotropic film on the other side so that the transmission axis of the polarizer and the in-plane slow axis of the film are parallel. Bonded polarizing plates 101 to 126 were obtained so that the combination shown in FIG.

<Heat unevenness>
Remove the polarizing plate of the Matsushita Electric 26-inch LCD TV, VIERA 26LX60 liquid crystal panel, and place the polarizing plate using the retardation film of the present invention instead on the viewing side of the liquid crystal panel and the liquid crystal layer on the liquid crystal cell side. Pasted together.

  On the backlight side, a polarizing plate using an isotropic cellulose triacetate (TAC) film whose phase difference was adjusted to Ro = 0.8 nm and Rt = 1.1 nm was bonded.

  These configurations are shown in FIG. In the figure, what is described as a TAC film was Konica Minolta Tack KC4UY (manufactured by Konica Minolta Opto).

  The viewing-side polarizing plate was produced as follows. A saponified KC4UY was bonded to one surface of a polarizer obtained by adsorbing iodine to a stretched polyvinyl alcohol film using a polyvinyl alcohol-based adhesive. On the other surface, the retardation film of the present invention was bonded using a polyurethane-based adhesive to produce a viewing side polarizing plate.

  The backlight side polarizing plate saponified the cellulose ester film as usual, and bonded using the polyvinyl alcohol-type adhesive agent, and produced the polarizing plate.

  The liquid crystal panel produced as described above was stored at 60 ° C. and 90% RH for 100 hours, the backlight was turned on to display black, and the intensity of unevenness was visually observed after 2 hours.

Situation Evaluation Strong unevenness at the four corners and cloudy unevenness on the entire surface ×
Strong unevenness occurs at the four corners △
Weak cloudy unevenness ○
No unevenness ◎

  As is clear from Table 3, it can be seen that the back layer produced a retardation film that was durable to environmental changes and had little alignment unevenness in the liquid crystal layer.

It is a general | schematic flow sheet of the manufacturing apparatus of the cellulose-ester film of this invention. It is the schematic of the liquid crystal display device of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Extruder 2 Filter 3 Static mixer 4 Casting die 5 Rotating support body (1st cooling roll)
6 Nipping pressure rotating body (touch roll)
7 Rotating support (second cooling roll)
8 Rotating support (3rd cooling roll)
9, 11, 13, 14, 15 Transport roll 10 Cellulose ester film 16 Winding device L-1, 9 TAC film L-2, 8 Polarizers The absorption axes of the polarizers 2 and 8 are orthogonal to each other. .

L-3 Cellulose ester film of the present invention L-4 Intermediate layer L-5 Optically anisotropic layer in which rod-like liquid crystal is vertically aligned and fixed in alignment L-6 Driving liquid crystal cell L-6-1 Viewing side glass Substrate L-6-2 Backlight side glass substrate L-6-3 Liquid crystal layer L-7 Isotropic cellulose triacetate film L-10 First polarizing plate (viewing side polarizing plate)
L-11 Retardation film of the present invention L-12 Second polarizing plate (backlight side polarizing plate)
L-13 Backlight

Claims (4)

In a retardation film having a cellulose ester film, an optically anisotropic layer in which a rod-like liquid crystal is vertically aligned on one surface thereof and the orientation is fixed, and a back layer on the other surface, the cellulose ester film is represented by the following formula: (A1) and (A2) are satisfied at the same time, the solvent content is 0.01% by mass or less, and the elastic modulus CE1 in the film forming direction at 23 ° C. and 55% RH is 1.5 to 2.5 kN / mm ² , The elastic modulus CE2 in the width direction is 1.8 to 3.5 kN / mm ² , and the elastic modulus BC of at least one layer of the back layer is (elastic modulus CE1 + elastic modulus CE2) / 2 <elastic modulus BC. A retardation film characterized by that.
Formula (A1) 2.0 ≦ X + Y ≦ 3.0
Formula (A2) 0.1 ≦ Y ≦ 2.5
(In the formula, X represents the degree of substitution of the acetyl group of the cellulose ester, and Y represents the degree of substitution of the propionyl group or butyryl group.)   The retardation film is selected from an acrylic polymer and an ester compound in which at least one of a pyranose structure or furanose structure is 1 to 12 and all or part of the OH groups of the structure are esterified. The retardation film according to claim 1, wherein the phase difference film is a cellulose ester film containing at least one kind.   A polarizing plate comprising a polarizer and two polarizing plate protective films sandwiching the polarizer, wherein at least one of the polarizing plate protective films is the retardation film according to claim 1 or 2. Board.   A liquid crystal display device comprising the retardation film according to claim 1.

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