JP5109783B2 - Polarizing plate and liquid crystal display device - Google Patents

Description

  The present invention relates to a polarizing plate and a liquid crystal display device, and more particularly to a polarizing plate excellent in viewing angle and corner unevenness in an environment of 25 ° C. and 90% RH.

  With high performance and high quality of liquid crystal display devices, various demands have been made as polarizing plate protective films used for polarizing plates.

  As a polarizing plate protective film for a liquid crystal display device that is generally used at present, a film made of cellulose ester is used. Cellulose ester films are generally formed by a solution casting method from the viewpoint of ensuring flatness, and the refractive index in the thickness direction tends to be lower than the refractive index in the film plane.

  Patent Document 1 describes a cellulose ester film in which optical anisotropy is reduced by adding an ethylenic polymer. In particular, in a film with reduced Rt, the polarizer is likely to be deteriorated after long-term durability. I understood.

  In addition, since the polarizing plate strongly affects the display performance (viewing angle, color, gradation) of the liquid crystal display, it has excellent dimensional stability, especially when used for long periods of time and at high humidity, and stability of retardation. In particular, it is required that the polarizer has excellent dimensional stability in the absorption axis direction and excellent polarizer deterioration.

  When the dimensional change of the polarizing plate is large when used for a long time or at high humidity, stress is generated between the polarizing plate and the liquid crystal cell bonded via the adhesive or adhesive layer, and the color becomes white when displaying black. A phenomenon called so-called corner unevenness occurs.

In particular, when a polarizing plate having a cellulose ester film with reduced optical anisotropy is used in a lateral electric field switching mode type (hereinafter referred to as IPS type) liquid crystal display device, it is used for a long time or adjusts the screen brightness. Then, it was found that due to the large amount of heat generated from the backlight, there was a phenomenon called corner unevenness and a change in visibility such as a decrease in viewing angle, and an immediate improvement was desired.
JP 2003-12859 A

  Accordingly, an object of the present invention is to provide a polarizing plate excellent in viewing angle and corner unevenness in an environment of 25 ° C. and 90% RH by a polarizing plate having a polarizer sandwiched between two types of cellulose ester films having specific elastic modulus. The object of the present invention is to provide a liquid crystal display device with excellent visibility using the same.

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

  1. Cellulose ester film (A) containing an acrylic polymer and satisfying the following formulas (1) and (2) and cellulose ester film (B) containing an acrylic polymer and satisfying the following formula (3) ( A) and (B) A polarizing plate comprising a polarizer sandwiched between two films.

1.4 ≦ (TD elastic modulus / MD elastic modulus) ≦ 2.2 (1)
1.3 ≦ (TD elastic modulus−MD elastic modulus) ≦ 4.0 (2)
0.9 ≦ (TD elastic modulus / MD elastic modulus) ≦ 1.1 (3)
(In the formula, the TD elastic modulus is the elastic modulus in the width direction of the film, and the MD elastic modulus refers to the elastic modulus in the film transport direction or the longitudinal direction)
2. 2. The TD elastic modulus of the cellulose ester film (A) satisfies the following formula (4), and the TD elastic modulus of the cellulose ester film (B) satisfies the following formula (5). Polarizing plate.

4.5 ≦ (TD elastic modulus) ≦ 7.0 (4)
3.0 ≦ (TD elastic modulus) ≦ 5.0 (5)
(In the formula, TD elastic modulus means the elastic modulus in the width direction of the film)
3. 1 or 2 above, wherein the cellulose ester film (A) has a TD elastic modulus and an MD elastic modulus in a region sandwiched between the following formulas (6) and (7): 2. The polarizing plate according to 2.

(TD elastic modulus−MD elastic modulus) = 2.27 × (TD elastic modulus / MD elastic modulus) −1.18
(6)
(TD elastic modulus−MD elastic modulus) = 1.45 × (TD elastic modulus / MD elastic modulus) −0.75
(7)
(In the formula, the TD elastic modulus is the elastic modulus in the width direction of the film, and the MD elastic modulus refers to the elastic modulus in the transport direction or longitudinal direction of the film).
4). 3. The polarizing plate as described in 1 or 2 above, wherein the cellulose ester film (A) is stretched in at least one direction at a stretching ratio of 1.2 times to 1.5 times.

  5). 3. The polarizing plate according to the above 1 or 2, wherein the cellulose ester film (A) has a curable resin layer on the surface opposite to the surface to be bonded to the polarizer.

  6). 3. The polarizing plate according to the above 1 or 2, wherein the cellulose ester film (A) has an antireflection layer on the surface opposite to the surface to be bonded to the polarizer.

  7). 7. A liquid crystal display device comprising the polarizing plate according to any one of 1 to 6 on at least one surface of a liquid crystal cell.

  According to the present invention, a polarizing plate excellent in viewing angle and corner unevenness in an environment of 25 ° C. and 90% RH is provided by a polarizing plate having a polarizer sandwiched between two types of cellulose ester films having specific elastic modulus. It is possible to provide a liquid crystal display device using the same and having excellent visibility.

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

  As a result of intensive studies on the above problems, the present inventors have determined the elastic modulus in the transport direction (MD direction) of the cellulose ester film and the width direction (TD direction) perpendicular to the transport direction by the following formulas (1) and (2 A polarizing plate using a polarizing plate protective film comprising a cellulose ester film (A) containing an acrylic polymer satisfying the following formula (3) and a cellulose ester film (B) containing an acrylic polymer satisfying the following formula (3): 90 ° C. It has been found that a polarizing plate excellent in viewing angle and corner unevenness in an environment of% RH can be obtained, and as a result of achieving the present invention.

1.4 ≦ (TD elastic modulus / MD elastic modulus) ≦ 2.2 (1)
1.3 ≦ (TD elastic modulus−MD elastic modulus) ≦ 4.0 (2)
0.9 ≦ (TD elastic modulus / MD elastic modulus) ≦ 1.1 (3)
In the present invention, the means for increasing the elastic modulus is preferably stretched in the range of 1.07 to 2.0 times in the direction to be increased, but the TD elastic modulus and MD elasticity represented by the formulas (1) and (2) When trying to stretch within the range of the rate, it is necessary to suppress the haze increase and retardation variation due to stretching. By containing an acrylic copolymer in the cellulose ester film, the present inventors can remarkably suppress an increase in haze and variation in retardation during stretching, and further the cellulose during stretching with an acrylic copolymer. It has been found that the disorder of molecular orientation can be highly suppressed, and that an excellent effect can be obtained in viewing angle and corner unevenness under high humidity.

  Moreover, in the configuration of the polarizing plate, high humidity is obtained by adjusting the TD elastic modulus of the cellulose ester film (A) to be bonded to the viewing side or the backlight side, which is more susceptible to environmental influences, to be higher than the MD elastic modulus. As soon as it has been found that the viewing angle and corner unevenness can be further improved, the present invention has been made.

  Therefore, the TD elastic modulus of the cellulose ester film (A) preferably satisfies the following formulas (4) and (5).

4.5 ≦ (TD elastic modulus) ≦ 7.0 (4)
3.0 ≦ (TD elastic modulus) ≦ 5.0 (5)
Hereinafter, the present invention will be described in detail.

《Elastic modulus》
The elastic modulus is also called the tensile elastic modulus (MPa). According to ISO 527-3, a tensile tester manufactured by Toyo Seiki Seisakusho Co., Ltd. was used, and a tensile test was performed at 23 ° C. and 55% RH. It was obtained from the intensity data.

  In the present invention, the elastic modulus in both directions of the transport direction (MD direction) of the cellulose ester film and the direction orthogonal to the transport direction (TD direction) is measured, and the cellulose ester film (A) containing the acrylic polymer is expressed by the formula (1). ), The formula (2), and the cellulose ester film (B) containing an acrylic polymer must satisfy the formula (3).

1.4 ≦ (TD elastic modulus / MD elastic modulus) ≦ 2.2 (1)
1.3 ≦ (TD elastic modulus−MD elastic modulus) ≦ 4.0 (2)
0.9 ≦ (TD elastic modulus / MD elastic modulus) ≦ 1.1 (3)
The formula (1) is preferably 1.6 ≦ (TD elastic modulus / MD elastic modulus) ≦ 2.0, and the formula (3) is preferably 0.95 ≦ (TD elastic modulus / MD elastic modulus) ≦ 1. 05.

  In order to adjust the elastic modulus within this range, the type and content of cellulose ester, the type and content of additives such as acrylic copolymer and various plasticizers, the cellulose ester film (A), (B) This can be achieved by appropriately controlling the stretching operation (stretching ratio, temperature, tension, residual solvent amount, etc.). In this, after adding the acrylic polymer mentioned later, controlling by the extending | stretching operation to TD direction and MD direction is a preferable embodiment when obtaining the effect of this invention, reducing a haze.

  2. The polarized light according to 1 above, wherein the TD elastic modulus of the cellulose ester film (A) satisfies the following formula (4), and the TD elastic modulus of the cellulose ester film (B) satisfies the following formula (5): Board.

4.5 ≦ (TD elastic modulus) ≦ 7.0 (4)
3.0 ≦ (TD elastic modulus) ≦ 5.0 (5)
Formula (4) is preferably 4.5 ≦ (TD elastic modulus) ≦ 6.0, and formula (5) is preferably 3.5 ≦ (TD elastic modulus) ≦ 4.5.

  Moreover, it is especially preferable when obtaining the effect of this invention that the TD elasticity modulus and MD elasticity modulus of a cellulose-ester film (A) exist in the area | region pinched | interposed between following formula (6), (7).

(TD elastic modulus−MD elastic modulus) = 2.27 × (TD elastic modulus / MD elastic modulus) −1.18
(6)
(TD elastic modulus−MD elastic modulus) = 1.45 × (TD elastic modulus / MD elastic modulus) −0.75
(7)
FIG. 1 is a correlation diagram of the TD elastic modulus and MD elastic modulus of the cellulose ester film (A). The region indicated by the solid line is the range described in claim 1, and the range indicated by the dotted line is claim 1 and is a range satisfying claim 3. The region surrounded by the dotted line and the alternate long and short dash line is the most preferable range in the present invention.

  FIG. 2 is a correlation diagram of the TD elastic modulus and MD elastic modulus of the cellulose ester film (B). Similarly, the range indicated by the solid line is the range described in claim 1. A region surrounded by a one-dot chain line is a more preferable range in the present invention.

《Acrylic copolymer》
The acrylic copolymer (hereinafter also referred to as acrylic polymer) contained in the cellulose ester films (A) and (B) is weight average in order to exert an effect on the increase in haze at the time of stretching and the stability of retardation. It is preferable to contain an acrylic polymer having a molecular weight of 500 or more and 30000 or less. Among them, an ethylenically unsaturated monomer Xa having no aromatic ring and a hydrophilic group in the molecule and a hydrophilic group having no aromatic ring in the molecule. A polymer X having a weight average molecular weight of 5,000 to 30,000 obtained by copolymerization with an ethylenically unsaturated monomer Xb, more preferably an ethylenically unsaturated monomer Xa having no aromatic ring and no hydrophilic group in the molecule; Weight average molecular weight of 5000 or more obtained by copolymerization with ethylenically unsaturated monomer Xb having no aromatic ring in the molecule and having a hydrophilic group 30000 and following polymers X, preferably contains a weight average molecular weight of 500 to 3,000 of the polymer Y obtained by polymerization of ethylenic unsaturated monomer Ya not having an aromatic ring.

<Polymer X, Polymer Y>
Polymer X is obtained by copolymerizing ethylenically unsaturated monomer Xa having no aromatic ring and hydrophilic group in the molecule and ethylenically unsaturated monomer Xb having no aromatic ring and having a hydrophilic group in the molecule. The obtained polymer having a weight average molecular weight of 5,000 to 30,000.

  Preferably, Xa is an acrylic or methacrylic monomer that does not have an aromatic ring and a hydrophilic group in the molecule, and Xb is an acrylic or methacrylic monomer that does not have an aromatic ring in the molecule and has a hydrophilic group.

  The polymer X is represented by the following general formula (X).

Formula (X)
-(Xa) m- (Xb) n- (Xc) p-
More preferably, it is 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 formula, R 1 and R ₃ represent H or CH _3. R ₂ represents an alkyl group having 1 to 12 carbon atoms or a cycloalkyl group. R ₄ represents —CH ₂ —, —C ₂ H ₄ — or —C _3. H _6- represents X. C represents a monomer unit that can be polymerized to Xa and Xb, and m, n, and p represent molar composition ratios, where m ≠ 0, n ≠ 0, and m + n + p = 100.
Although the monomer as a monomer unit which comprises the polymer X is mentioned below, it is not limited to this.

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

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

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

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

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

  When the molar composition ratio of Xa is large, the compatibility with the cellulose ester is improved, but the retardation value Rt in the film thickness direction is increased. When the molar composition ratio of Xb is large, the compatibility is deteriorated, but the effect of reducing Rt is high. Further, if the molar composition ratio of Xb exceeds the above range, haze tends to occur during film formation, and it is preferable to optimize these and determine the molar composition ratio of Xa and Xb.

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

  By making the weight average molecular weight 5000 or more, the cellulose ester films (A) and (B) have advantages such as little dimensional change under high temperature and high humidity, and less curl when used as a protective film for polarizing plates. It is preferable. When the weight average molecular weight is within 30000, the compatibility with the cellulose ester is further improved, bleeding out under high temperature and high humidity, and further haze generation during stretching are suppressed.

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

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

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

  The measurement conditions are as follows.

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

  The polymer Y is a polymer having a weight average molecular weight of 500 or more and 3000 or less obtained by polymerizing an ethylenically unsaturated monomer Ya having no aromatic ring. A weight average molecular weight of 500 or more is preferable because the residual monomer of the polymer 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 is represented by the following general formula (Y).

General formula (Y)
-(Ya) k- (Yb) q-
More preferably, it is a polymer represented by the following general formula (Y-1).

General formula (Y-1)
_{- [CH 2 -C (-R5)} (- CO 2 R6)] k- [Yb] q-
(Wherein, R5 is, .Yb .R6 representing H or CH ₃ is representing an alkyl group or a cycloalkyl group having 1 to 12 carbon atoms, .k and q represents the Ya and copolymerizable monomer units, This represents the molar composition ratio, where k ≠ 0 and k + q = 100.)
Yb is not particularly limited as long as it is an ethylenically unsaturated monomer copolymerizable with Ya. Yb may be plural. k + q = 100, q is preferably 0-30.

  The ethylenically unsaturated monomer Ya constituting the polymer Y obtained by polymerizing an ethylenically unsaturated monomer having no aromatic ring is, for example, methyl acrylate, ethyl acrylate, propyl acrylate (i- , N-), butyl acrylate (n-, i-, s-, t-), pentyl acrylate (n-, i-, s-), hexyl acrylate (n-, i-), heptyl acrylate (N-, i-), octyl acrylate (n-, i-), nonyl acrylate (n-, i-), myristyl acrylate (n-, i-), cyclohexyl acrylate, acrylic acid (2- Ethyl hexyl), acrylic acid (ε-caprolactone), acrylic acid (2-hydroxyethyl), acrylic acid (2-hydroxypropyl), acrylic acid (3-hydroxypropiyl) ), Acrylic acid (4-hydroxybutyl), acrylic acid (2-hydroxybutyl), methacrylic acid ester, the above acrylic acid ester changed to methacrylic acid ester; unsaturated acid, for example, acrylic acid, methacrylic acid And maleic anhydride, crotonic acid, itaconic acid and the like.

  Yb is not particularly limited as long as it is an ethylenically unsaturated monomer copolymerizable with Ya. Examples of vinyl esters include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl valerate, vinyl pivalate, and vinyl caproate. Vinyl caprate, vinyl laurate, vinyl myristate, vinyl palmitate, vinyl stearate, vinyl cyclohexanecarboxylate, vinyl octylate, vinyl methacrylate, vinyl crotonate, vinyl sorbate, vinyl cinnamate and the like are preferred. Yb may be plural.

  In order to synthesize the polymers X and Y, it is difficult to control the molecular weight in normal polymerization, and it is desirable to use a method that can make the molecular weights as uniform as possible without increasing the molecular weight. Such polymerization methods include a method using a peroxide polymerization initiator such as cumene peroxide and t-butyl hydroperoxide, a method using a polymerization initiator in a larger amount than normal polymerization, and a mercapto compound in addition to the polymerization initiator. And a method of using a chain transfer agent such as carbon tetrachloride, a method of using a polymerization terminator such as benzoquinone and dinitrobenzene in addition to the polymerization initiator, and further, Japanese Patent Application Laid-Open No. 2000-128911 or 2000-344823. Examples 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. In particular, polymer Y uses a compound having a thiol group and a secondary hydroxyl group in the molecule as a chain transfer agent. The polymerization method of use is preferred. 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 of 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 [mg KOH / g].

(Measurement method of hydroxyl value)
This measurement conforms to JIS K 0070 (1992). This hydroxyl value is defined as the number of mg of potassium hydroxide required to neutralize 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
(Wherein B is the amount of 0.5 mol / L potassium hydroxide ethanol solution used in the blank test (ml), and C is the amount of 0.5 mol / L potassium hydroxide ethanol solution used in the titration (ml). F is a factor of 0.5 mol / L potassium hydroxide ethanol solution, D is an acid value, and 28.05 is 1/2 of 1 mol amount of potassium hydroxide 56.11)
All of the above-mentioned X polymer polymers Y have excellent compatibility with cellulose esters, excellent productivity without evaporation and volatilization, good retention as a protective film for polarizing plates, low moisture permeability, and excellent dimensional stability. ing.

The content of the polymer X and the polymer Y in the cellulose ester films (A) and (B) is preferably in a range satisfying the following formulas (i) and (ii). When the content of the polymer X is Xg (mass% = the mass of the polymer X / the mass of the cellulose ester × 100) and the content of the polymer Y is Yg (mass%),
Formula (i) 5 ≦ Xg + Yg ≦ 35 (mass%)
Formula (ii) 0.05 ≦ Yg / (Xg + Yg) ≦ 0.4
A preferable range of the formula (i) is 10 to 25% by mass.

  If the total amount of the polymer X and the polymer Y is 5% by mass or more, the polymer X and the polymer Y sufficiently act to reduce the retardation value Rt. Moreover, if it is 35 mass% or less as a total amount, adhesiveness with a polyvinyl alcohol-type polarizer will be favorable.

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

<< Compound with furanose structure or pyranose structure >>
Cellulose ester films (A) and (B) have at least one furanose structure or pyranose structure, and all or part of OH groups in a compound having 1 to 12 furanose structures or pyranose structures bonded thereto are esterified. It is also preferable from a viewpoint of a haze fall to contain the compound (henceforth a sugar ester compound) which was made. Examples of preferable “compounds having at least one furanose structure or pyranose structure and having 1 to 12 furanose structures or pyranose structures bound thereto” include, for example, the following. It is not limited to these.

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

  “A compound (sugar ester compound) in which all or part of OH groups in a compound having at least one furanose structure or pyranose structure and 1 to 12 furanose structures or pyranose structures bonded to each other is esterified” is synthesized. The monocarboxylic acid used at the time is not particularly limited, and the sugar ester compound used in the present invention is esterified with a known aliphatic monocarboxylic acid, alicyclic monocarboxylic acid, aromatic monocarboxylic acid, or the like. Can be synthesized. The carboxylic acid used may be one type or a mixture of two or more types.

  Preferred aliphatic monocarboxylic acids include acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2-ethyl-hexanecarboxylic acid, undecylic acid, lauric acid , Saturated fatty acids such as tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, melicic acid, and laccelic acid, Examples include unsaturated fatty acids such as undecylenic acid, oleic acid, sorbic acid, linoleic acid, linolenic acid, arachidonic acid and octenoic acid.

  Examples of preferred alicyclic monocarboxylic acids include cyclopentane carboxylic acid, cyclohexane carboxylic acid, cyclooctane carboxylic acid, or derivatives thereof.

  Examples of preferable aromatic monocarboxylic acids include aromatic monocarboxylic acids and cinnamic acids having 1 to 5 substituents such as alkyl groups or alkoxy groups introduced into the benzene ring of benzoic acid such as benzoic acid and toluic acid. An aromatic monocarboxylic acid having two or more benzene rings such as benzyl acid, biphenyl carboxylic acid, naphthalene carboxylic acid, tetralin carboxylic acid, or a derivative thereof may be mentioned, and benzoic acid is particularly preferable.

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

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

  In order to suppress the occurrence of haze during stretching, the sugar ester compound is preferably contained in the cellulose ester films (A) and (B) in an amount of 1 to 35% by mass, particularly 5 to 30% by mass.

《Cellulose ester》
The cellulose ester used in the cellulose ester films (A) and (B) is not particularly limited, but the cellulose ester is a carboxylic acid ester having about 2 to 22 carbon atoms, and may be an aromatic carboxylic acid ester, particularly cellulose. The lower fatty acid ester is preferable. 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. When the degree of substitution is the same, birefringence decreases when the number of carbon atoms is large, and therefore, the number of carbon atoms is preferably selected from acyl groups having 2 to 6 carbon atoms. The cellulose ester preferably has 2 to 4 carbon atoms, more preferably 2 to 3 carbon atoms.

  The cellulose ester may be an acyl group derived from a mixed acid, and particularly preferably an acyl group having 2 and 3 carbon atoms or 2 and 4 carbon atoms. In the present invention, as a cellulose ester, a mixed fatty acid ester of cellulose to which a propionate group or a butyrate group is bonded in addition to an acetyl group such as cellulose acetate propionate, cellulose acetate butyrate, or cellulose acetate propionate butyrate is used. Can do. The butyryl group forming butyrate may be linear or branched. As the cellulose ester preferably used in the present invention, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, and cellulose acetate phthalate are particularly preferably used.

  The retardation value can be appropriately controlled depending on the kind of the acyl group of the cellulose ester and the degree of substitution of the acyl group with the pyranose ring of the cellulose resin skeleton.

  Preferred cellulose esters for the present invention are those that simultaneously satisfy the following formulas (1) and (2).

Formula (1) 2.0 <= X + Y <= 3.0
Formula (2) 0 ≦ Y ≦ 1.5
In the formula, X is the degree of substitution of the acetyl group, and Y is the degree of substitution of the propionyl group or butyryl group. The cellulose ester satisfying the above two formulas has an excellent effect that haze generation during stretching can be suppressed.

  Of these, triacetyl cellulose and cellulose acetate propionate are particularly preferably used. In cellulose acetate propionate, 1.0 ≦ X ≦ 2.5, preferably 0.1 ≦ Y ≦ 1.5, and 2.0 ≦ X + Y ≦ 3.0. The measuring method of the substitution degree of an acyl group can be measured according to ASTM-D817-96.

  If the substitution degree of the acyl group is too low, there will be more unreacted parts with respect to the hydroxyl groups of the pyranose ring constituting the skeleton of the cellulose resin. The ability to protect the polarizer as a film may decrease, which is not preferable.

  The weight average molecular weight (Mw) of the cellulose ester is preferably in the range of 260000 to 500000, more preferably in the range of 290000 to 400000.

  The weight average molecular weight (Mw) of a cellulose ester can be measured as follows.

  Measured by high performance liquid chromatography under the following conditions.

Solvent: Acetone Column: MPW × 1 (manufactured by Tosoh Corporation)
Sample concentration: 0.2 (mass / volume)%
Flow rate: 1.0 ml / min Sample injection volume: 300 μl
Standard sample: Standard polystyrene Temperature: 23 ° C
Although there is no limitation in particular as a cellulose of the raw material of a cellulose ester, Wood pulp (a softwood pulp, a hardwood pulp), a cotton linter, etc. can be used. The Mw of the cellulose ester can be controlled by the type of cellulose and the use of a plurality of raw material celluloses. For example, if esterification is performed using pre-hydrolysis kraft pulp, the Mw of the cellulose ester increases, and if softwood sulfite pulp is used, the Mw tends to decrease. Therefore, cellulose may be used singly or in combination of two or more. For example, softwood pulp and cotton linter or hardwood pulp may be used in combination. As cellulose, usually pulp (particularly softwood pulp) is often used. In addition, the α-cellulose content (% by mass) of cellulose is usually from 94 to 99 (for example, 95 to 99), preferably from about 96 to 98.5 (for example, 97.3 to 98). .

When the acylating agent of the cellulose raw material is an acid anhydride (acetic anhydride, propionic anhydride, butyric anhydride), the cellulose ester according to the present invention uses an organic solvent such as acetic acid or an organic solvent such as methylene chloride. The reaction is carried out using a protic catalyst such as sulfuric acid. When the acylating agent is acid chloride (CH ₃ COCl, C ₂ H ₅ COCl, C ₃ H ₇ COCl), the reaction is carried out using a basic compound such as an amine as a catalyst. Specifically, it can be synthesized with reference to the method described in JP-A-10-45804.

  The average substitution degree of the acyl group at the 6-position of the glucose unit of the cellulose ester used in the present invention is preferably 0.5 to 0.9.

  Unlike the 2nd and 3rd positions, the glucose unit constituting the cellulose ester has a highly reactive primary hydroxyl group, and this primary hydroxyl group is sulfated during the production of cellulose ester using sulfuric acid as a catalyst. Esters are preferentially formed. Therefore, by increasing the amount of the catalytic sulfuric acid in the cellulose estilation reaction, the average substitution degree at the 2nd and 3rd positions of the glucose unit can be increased as compared with the ordinary cellulose ester. Furthermore, if the cellulose is tritylated as necessary, the hydroxyl group at the 6-position of the glucose unit can be selectively protected. Therefore, the trityl group protects the hydroxyl group at the 6-position, and after esterification, the trityl group (protection) The average substitution degree at the 2nd and 3rd positions can be increased from the 6th position of the glucose unit. Specifically, a cellulose ester produced by the method described in JP-A No. 2005-281645 can also be preferably used.

  In the case of acetylcellulose, it is necessary to extend the time for the acetylation reaction in order to increase the acetylation rate. However, if the reaction time is too long, the decomposition proceeds at the same time, and the polymer chain is broken and the acetyl group is decomposed, resulting in undesirable results. Therefore, it is necessary to set the reaction time within a certain range in order to increase the degree of acetylation and suppress decomposition to some extent. It is not appropriate to define the reaction time because the reaction conditions are various and greatly change depending on the reaction apparatus, equipment and other conditions. As the decomposition of the polymer progresses, the molecular weight distribution becomes wider. Therefore, in the case of cellulose ester, the degree of decomposition can be defined by the value of weight average molecular weight (Mw) / number average molecular weight (Mn) that is usually used. In other words, in the process of acetylation of cellulose triacetate, the weight average molecular weight used as one index of the reaction degree for allowing the acetylation reaction to be carried out for a sufficient time for acetylation without being excessively decomposed too much. The value of (Mw) / number average molecular weight (Mn) can be used.

  An example of a method for producing a cellulose ester is shown below: 100 parts by mass of a flocculent linter was crushed as a cellulose raw material, 40 parts by mass of acetic acid was added, and pretreatment activation was performed at 36 ° C. for 20 minutes. Thereafter, 8 parts by mass of sulfuric acid, 260 parts by mass of acetic anhydride and 350 parts by mass of acetic acid were added, and esterification was performed at 36 ° C. for 120 minutes. After neutralization with 11 parts by mass of a 24% magnesium acetate aqueous solution, saponification aging was carried out at 63 ° C. for 35 minutes to obtain acetylcellulose. This was stirred for 160 minutes at room temperature using a 10-fold acetic acid aqueous solution (acetic acid: water = 1: 1 (mass ratio)), then filtered and dried to obtain purified acetylcellulose having an acetyl substitution degree of 2.75. . This acetylcellulose had Mn of 92000, Mw of 156000, and Mw / Mn of 1.7. Similarly, cellulose esters having different degrees of substitution and Mw / Mn ratios can be synthesized by adjusting the esterification conditions (temperature, time, stirring) and hydrolysis conditions of the cellulose ester. The Mw / Mn ratio of the cellulose ester is preferably 1.4 to 5.0.

  The synthesized cellulose ester is preferably purified to remove low molecular weight components or to remove unacetylated or low acetylated components by filtration.

  In the case of mixed acid cellulose ester, it can be obtained by the method described in JP-A-10-45804.

  Cellulose esters are also affected by trace metal components in cellulose esters. These are considered to be related to water used in the production process, but it is preferable that there are few components that can become insoluble nuclei, and metal ions such as iron, calcium, and magnesium contain organic acidic groups. Insoluble matter may be formed by salt formation with a polymer degradation product or the like that may be present, and it is preferable that the amount is small. The iron (Fe) component is preferably 1 ppm or less. As for the calcium (Ca) component, it is easy to form a coordination compound, that is, a complex with an acidic component such as carboxylic acid or sulfonic acid, and many ligands. Starch, turbidity).

  The calcium (Ca) component is 60 ppm or less, preferably 0 to 30 ppm. The magnesium (Mg) component is preferably in the range of 0 to 70 ppm, particularly preferably 0 to 20 ppm, since too much will cause insoluble matter. Metal components such as iron (Fe) content, calcium (Ca) content, magnesium (Mg) content, etc. are pre-processed by completely digesting cellulose ester with micro digest wet cracking equipment (sulfuric acid decomposition) and alkali melting. After being performed, it can be analyzed using ICP-AES (Inductively Coupled Plasma Atomic Emission Spectrometer).

(Plasticizer)
The cellulose ester films (A) and (B) of the present invention can contain a plasticizer as necessary to obtain the effects of the present invention. The plasticizer is not particularly limited, but is preferably a polycarboxylic acid ester plasticizer, a glycolate plasticizer, a phthalate ester plasticizer, a fatty acid ester plasticizer, a polyhydric alcohol ester plasticizer, or a polyester plasticizer. Agent, acrylic plasticizer and the like. Of these, when two or more plasticizers are used, at least one plasticizer is preferably a polyhydric alcohol ester plasticizer.

  The polyhydric alcohol ester plasticizer is a compound represented by the following general formula (1).

Formula (1) R1- (OH) n
(In the formula, R1 represents an n-valent organic group, and n represents a positive integer of 2 or more)
Examples of preferred polyhydric alcohols include the following, but the present invention is not limited to these. Adonitol, arabitol, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, dipropylene glycol, tripropylene glycol, 1,2-butanediol, 1,3- Butanediol, 1,4-butanediol, dibutylene glycol, 1,2,4-butanetriol, 1,5-pentanediol, 1,6-hexanediol, hexanetriol, galactitol, mannitol, 3-methylpentane- Examples thereof include 1,3,5-triol, pinacol, sorbitol, trimethylolpropane, trimethylolethane, xylitol, pentaerythritol, dipentaerythritol and the like. Of these, trimethylolpropane and pentaerythritol are preferable.

  There is no restriction | limiting in particular as monocarboxylic acid used for polyhydric alcohol ester, Well-known aliphatic monocarboxylic acid, alicyclic monocarboxylic acid, aromatic monocarboxylic acid, etc. can be used. Use of an alicyclic monocarboxylic acid or aromatic monocarboxylic acid is preferable in terms of improving moisture permeability and retention. Examples of preferred monocarboxylic acids include the following, but are not limited thereto.

  As the aliphatic monocarboxylic acid, a fatty acid having a straight chain or a side chain having 1 to 32 carbon atoms can be preferably used. It is more preferable that it is C1-C20, and it is especially preferable that it is C1-C10. The use of acetic acid is preferred because the compatibility with the cellulose ester is increased, and it is also preferred to use a mixture of acetic acid and another monocarboxylic acid.

  Preferred aliphatic monocarboxylic acids include acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2-ethyl-hexanecarboxylic acid, undecylic acid, lauric acid, tridecylic acid , Saturated fatty acids such as myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, melicic acid, laccelic acid, undecylenic acid, Examples thereof include unsaturated fatty acids such as oleic acid, sorbic acid, linoleic acid, linolenic acid and arachidonic acid. Examples of preferred alicyclic monocarboxylic acids include cyclopentane carboxylic acid, cyclohexane carboxylic acid, cyclooctane carboxylic acid, or derivatives thereof. Examples of preferred aromatic monocarboxylic acids include those in which an alkyl group is introduced into the benzene ring of benzoic acid such as benzoic acid and toluic acid, and two or more benzene rings such as biphenyl carboxylic acid, naphthalene carboxylic acid, and tetralin carboxylic acid. The aromatic monocarboxylic acid which has, or those derivatives can be mentioned. In particular, benzoic acid is preferred.

  The molecular weight of the polyhydric alcohol ester is preferably in the range of 300 to 1500, and more preferably in the range of 350 to 750. A higher molecular weight is preferred because it is less likely to volatilize, and a smaller one is preferred in terms of moisture permeability and compatibility with cellulose ester. The carboxylic acid used for the polyhydric alcohol ester may be one kind or a mixture of two or more kinds. Moreover, all the OH groups in the polyhydric alcohol may be esterified, or a part of the OH groups may be left as they are. The specific compound of a polyhydric alcohol ester is shown below.

  In addition, trimethylolpropane triacetate, pentaerythritol tetraacetate and the like are also preferably used.

  The glycolate plasticizer is not particularly limited, but alkylphthalylalkyl glycolates can be preferably used. Examples of alkyl phthalyl alkyl glycolates include methyl phthalyl methyl glycolate, ethyl phthalyl ethyl glycolate, propyl phthalyl propyl glycolate, butyl phthalyl butyl glycolate, octyl phthalyl octyl glycolate, methyl phthalyl ethyl Glycolate, ethyl phthalyl methyl glycolate, ethyl phthalyl propyl glycolate, methyl phthalyl butyl glycolate, ethyl phthalyl butyl glycolate, butyl phthalyl methyl glycolate, butyl phthalyl ethyl glycolate, propyl phthalyl butyl glycol Butyl phthalyl propyl glycolate, methyl phthalyl octyl glycolate, ethyl phthalyl octyl glycolate, octyl phthalyl methyl glycolate, octyl phthalate Ethyl glycolate, and the like.

  Examples of the phthalate ester plasticizer include diethyl phthalate, dimethoxyethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, dioctyl phthalate, dicyclohexyl phthalate, and dicyclohexyl terephthalate.

  Examples of the citrate plasticizer include acetyl trimethyl citrate, acetyl triethyl citrate, and acetyl tributyl citrate.

  Examples of fatty acid ester plasticizers include butyl oleate, methylacetyl ricinoleate, and dibutyl sebacate.

  Examples of the phosphate ester plasticizer include triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, diphenyl biphenyl phosphate, trioctyl phosphate, tributyl phosphate and the like.

  The polyvalent carboxylic acid ester compound is composed of an ester of divalent or higher, preferably divalent to 20 valent polyvalent carboxylic acid and alcohol. The aliphatic polyvalent carboxylic acid is preferably 2 to 20 valent, and in the case of an aromatic polyvalent carboxylic acid or an alicyclic polyvalent carboxylic acid, it is preferably 3 to 20 valent.

  The polyvalent carboxylic acid is represented by the following general formula (2).

General formula (2) R2 (COOH) m (OH) n
(Wherein R2 is an (m + n) -valent organic group, m is a positive integer of 2 or more, n is an integer of 0 or more, a COOH group is a carboxyl group, and an OH group is an alcoholic or phenolic hydroxyl group)
Examples of preferred polyvalent carboxylic acids include the following, but the present invention is not limited to these. Trivalent or higher aromatic polyvalent carboxylic acids such as trimellitic acid, trimesic acid, pyromellitic acid or derivatives thereof, succinic acid, adipic acid, azelaic acid, sebacic acid, oxalic acid, fumaric acid, maleic acid, tetrahydrophthal An aliphatic polyvalent carboxylic acid such as an acid, an oxypolyvalent carboxylic acid such as tartaric acid, tartronic acid, malic acid and citric acid can be preferably used. In particular, it is preferable to use an oxypolycarboxylic acid from the viewpoint of improving retention.

  There is no restriction | limiting in particular as alcohol used for the polyhydric carboxylic acid ester compound which can be used for this invention, Well-known alcohol and phenols can be used. For example, an aliphatic saturated alcohol or aliphatic unsaturated alcohol having a straight chain or a side chain having 1 to 32 carbon atoms can be preferably used. It is more preferable that it is C1-C20, and it is especially preferable that it is C1-C10. In addition, alicyclic alcohols such as cyclopentanol and cyclohexanol or derivatives thereof, aromatic alcohols such as benzyl alcohol and cinnamyl alcohol, or derivatives thereof can also be preferably used.

  When an oxypolycarboxylic acid is used as the polycarboxylic acid, the alcoholic or phenolic hydroxyl group of the oxypolycarboxylic acid may be esterified with a monocarboxylic acid. Examples of preferred monocarboxylic acids include the following, but the present invention is not limited thereto.

  As the aliphatic monocarboxylic acid, a fatty acid having a straight chain or a side chain having 1 to 32 carbon atoms can be preferably used. It is more preferable that it is C1-C20, and it is especially preferable that it is C1-C10.

  Preferred aliphatic monocarboxylic acids include acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2-ethyl-hexanecarboxylic acid, undecylic acid, lauric acid, tridecylic acid, Saturated fatty acids such as myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, melicic acid, and laccelic acid, undecylenic acid, olein Examples thereof include unsaturated fatty acids such as acid, sorbic acid, linoleic acid, linolenic acid, and arachidonic acid.

  Examples of preferred alicyclic monocarboxylic acids include cyclopentane carboxylic acid, cyclohexane carboxylic acid, cyclooctane carboxylic acid, or derivatives thereof.

  Examples of preferred aromatic monocarboxylic acids include those in which an alkyl group is introduced into the benzene ring of benzoic acid such as benzoic acid and toluic acid, and two or more benzene rings such as biphenyl carboxylic acid, naphthalene carboxylic acid, and tetralin carboxylic acid. And aromatic monocarboxylic acids possessed by them, or derivatives thereof. Particularly preferred are acetic acid, propionic acid, and benzoic acid.

  The molecular weight of the polyvalent carboxylic acid ester compound is not particularly limited, but is preferably in the range of 300 to 1000, and more preferably in the range of 350 to 750. The larger one is preferable in terms of improvement in retention, and the smaller one is preferable in terms of moisture permeability and compatibility with cellulose ester.

  The alcohol used for the polyvalent carboxylic acid ester may be one kind or a mixture of two or more kinds.

  The acid value of the polyvalent carboxylic acid ester compound is preferably 1 mgKOH / g or less, and more preferably 0.2 mgKOH / g or less. Setting the acid value in the above range is preferable because the environmental fluctuation of the retardation is also suppressed.

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

  Examples of particularly preferred polyvalent carboxylic acid ester compounds are shown below, but the present invention is not limited thereto. For example, triethyl citrate, tributyl citrate, acetyl triethyl citrate (ATEC), acetyl tributyl citrate (ATBC), benzoyl tributyl citrate, acetyl triphenyl citrate, acetyl tribenzyl citrate, dibutyl tartrate, diacetyl dibutyl tartrate, Examples include tributyl trimellitic acid and tetrabutyl pyromellitic acid.

  The polyester plasticizer is not particularly limited, and a polyester plasticizer having an aromatic ring or a cycloalkyl ring in the molecule can be used. Although it does not specifically limit as a polyester plasticizer, For example, the aromatic terminal ester plasticizer represented by following General formula (3) can be used.

General formula (3) B- (GA) n-GB
(In the formula, B is a benzene monocarboxylic 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 the general formula (3), a benzene monocarboxylic acid residue represented by B and an alkylene glycol residue, oxyalkylene glycol residue or aryl glycol residue represented by G, an alkylene dicarboxylic acid residue or aryl dicarboxylic group represented by A It is composed of an acid residue and can be obtained by a reaction similar to that of a normal polyester plasticizer.

  Examples of the benzene monocarboxylic acid component of the polyester plasticizer used in the present invention include benzoic acid, para-tert-butylbenzoic acid, orthotoluic acid, metatoluic acid, p-toluic acid, dimethylbenzoic acid, ethylbenzoic acid, and normalpropyl. There exist benzoic acid, aminobenzoic acid, acetoxybenzoic acid, etc., and these can be used as 1 type, or 2 or more types of mixtures, respectively.

  Examples of the alkylene glycol component having 2 to 12 carbon atoms of the polyester plasticizer that can be used in the present invention include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 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-propanediol (neo Pentyl glycol), 2,2-diethyl-1,3-propanediol (3,3-dimethylolpentane), 2-n-butyl-2-ethyl-1,3propanediol (3,3-dimethylolheptane) 3-methyl-1,5-pentanediol 1,6-hexanediol, 2,2,4-trimethyl 1,3-penta Diol, 2-ethyl 1,3-hexanediol, 2-methyl 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-octadecanediol, and the like. It is used as one kind or a mixture of two or more kinds. In particular, an alkylene glycol having 2 to 12 carbon atoms is particularly preferable because of excellent compatibility with a cellulose ester.

  In addition, examples of the oxyalkylene glycol component having 4 to 12 carbon atoms of the aromatic terminal ester include diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, and tripropylene glycol. It can be used as a seed or a mixture of two or more.

  Examples of the alkylene dicarboxylic acid component having 4 to 12 carbon atoms of the aromatic terminal ester include succinic acid, maleic acid, fumaric acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, and dodecanedicarboxylic acid. These are used as one kind or a mixture of two or more kinds. Examples of the arylene dicarboxylic acid component having 6 to 12 carbon atoms include phthalic acid, terephthalic acid, isophthalic acid, 1,5 naphthalene dicarboxylic acid, and 1,4 naphthalene dicarboxylic acid.

  The polyester plasticizer used in the present invention has a number average molecular weight of preferably 300 to 1500, more preferably 400 to 1000. The acid value is 0.5 mgKOH / g or less, the 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.

  Hereinafter, synthesis examples of aromatic terminal ester plasticizers that can be used in the present invention will be shown.

<Sample No. 1 (Aromatic terminal ester sample)>
A reaction vessel was charged with 410 parts of phthalic acid, 610 parts of benzoic acid, 737 parts of dipropylene glycol, and 0.40 part of tetraisopropyl titanate as a catalyst. While refluxing the monohydric alcohol, heating was continued at 130 to 250 ° C. until the acid value became 2 or less, and water produced was continuously removed. Next, the distillate is removed under reduced pressure at 200 to 230 ° C. under a reduced pressure of 1.33 × 10 ⁴ Pa to 4 × 10 ² Pa or less, and then filtered to remove an aromatic terminal ester plastic having the following properties: An agent was obtained.

Viscosity (25 ° C., mPa · s); 43400
Acid value: 0.2
<Sample No. 2 (Aromatic terminal ester sample)>
Sample No. 1 was used except that 410 parts of phthalic acid, 610 parts of benzoic acid, 341 parts of ethylene glycol, and 0.35 part of tetraisopropyl titanate as a catalyst were used in the reaction vessel. In the same manner as in No. 1, an aromatic terminal ester having the following properties was obtained.

Viscosity (25 ° C., mPa · s); 31000
Acid value: 0.1
<Sample No. 3 (Aromatic terminal ester sample)>
Sample No. 1 was used except that 410 parts of phthalic acid, 610 parts of benzoic acid, 418 parts of 1,2-propanediol, and 0.35 part of tetraisopropyl titanate as the catalyst were used in the reaction vessel. In the same manner as in No. 1, an aromatic terminal ester having the following properties was obtained.

Viscosity (25 ° C., mPa · s); 38000
Acid value: 0.05
<Sample No. 4 (Aromatic terminal ester sample)>
Sample No. 4 was used except that 410 parts of phthalic acid, 610 parts of benzoic acid, 418 parts of 1,3-propanediol, and 0.35 part of tetraisopropyl titanate as a catalyst were used in the reaction vessel. In the same manner as in No. 1, an aromatic terminal ester having the following properties was obtained.

Viscosity (25 ° C., mPa · s); 37000
Acid value: 0.05
Although the specific compound of the aromatic terminal ester plasticizer which can be used for this invention below is shown, this invention is not limited to this.

(UV absorber)
The cellulose ester films (A) and (B) can also contain an ultraviolet absorber. The ultraviolet absorber is intended to improve durability by absorbing ultraviolet rays of 400 nm or less, and in particular, the transmittance at a wavelength of 370 nm is preferably 10% or less, more preferably 5% or less, and further Preferably it is 2% or less.

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

  For example, 5-chloro-2- (3,5-di-sec-butyl-2-hydroxylphenyl) -2H-benzotriazole, (2-2H-benzotriazol-2-yl) -6- (linear and side Chain dodecyl) -4-methylphenol, 2-hydroxy-4-benzyloxybenzophenone, 2,4-benzyloxybenzophenone, etc., and tinuvin 109, tinuvin 171, tinuvin 234, tinuvin 326, tinuvin 327, tinuvin 328, etc. These are commercially available products manufactured by Ciba Japan Co., Ltd. and can be preferably used.

  The UV absorbers preferably used in the present invention are benzotriazole UV absorbers, benzophenone UV absorbers, and triazine UV absorbers, particularly preferably benzotriazole UV absorbers and benzophenone UV absorbers. .

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

In the formula, R ₁ , R ₂ , R ₃ , R ₄ and R ₅ may be the same or different, and are a hydrogen atom, a halogen atom, a nitro group, a hydroxyl group, an alkyl group, an alkenyl group, an aryl group, an alkoxyl group, an acyloxy group. Represents a group, aryloxy group, alkylthio group, arylthio group, mono- or dialkylamino group, acylamino group or 5- to 6-membered heterocyclic group, and R ₄ and R ₅ are closed to form a 5- to 6-membered carbocycle May be.

  Moreover, these groups described above may have an arbitrary substituent.

  Although the specific example of the benzotriazole type ultraviolet absorber used for this invention below is given, this invention is not limited to these.

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

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

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

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

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

  It is preferable that the polarizing plate protective film concerning this invention contains 2 or more types of ultraviolet absorbers.

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

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

  The amount of UV absorber used is not uniform depending on the type of UV absorber, usage conditions, etc., but when the cellulose ester films (A) and (B) have a dry film thickness of 30 to 200 μm, On the other hand, 0.5-10 mass% is preferable and 0.6-4 mass% is still more preferable.

(Fine particles)
The cellulose ester films (A) and (B) of the present invention preferably contain fine particles.

  As fine particles, examples of inorganic compounds include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, Examples thereof include magnesium silicate and calcium phosphate. Fine particles containing silicon are preferable in terms of low turbidity, and silicon dioxide is particularly preferable.

  The average primary particle diameter of the fine particles is preferably 5 to 400 nm, and more preferably 10 to 300 nm. These may be mainly contained as secondary aggregates having a particle size of 0.05 to 0.3 μm, and may be contained as primary particles without being aggregated if the particles have an average particle size of 100 to 400 nm. preferable. The content of these fine particles in the cellulose ester films (A) and (B) is preferably 0.01 to 1% by mass, and particularly preferably 0.05 to 0.5% by mass. In the case of the cellulose ester films (A) and (B) having a multilayer structure by the co-casting method, it is preferable to contain fine particles of this addition amount on the surface.

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

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

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

  Among these, Aerosil 200V and Aerosil R972V are particularly preferably used because they have a large effect of reducing the friction coefficient while keeping the haze of the cellulose ester films (A) and (B) low. In the cellulose ester films (A) and (B) of the present invention, the dynamic friction coefficient of at least one surface is preferably 0.2 to 1.0.

(dye)
A dye may be added to the cellulose ester films (A) and (B) of the present invention for color adjustment. For example, a blue dye may be added to suppress the yellowness of the film. Preferred examples of the dye include anthraquinone dyes.

  The anthraquinone dye may have an arbitrary substituent at an arbitrary position from the 1st position to the 8th position of the anthraquinone. Preferred substituents include an anilino group, hydroxyl group, amino group, nitro group, or hydrogen atom. In particular, it is preferable to contain a blue dye described in JP-A-2001-154017, particularly an anthraquinone dye.

  Various additives may be batch-added to a dope that is a cellulose ester-containing solution before film formation, or an additive solution may be separately prepared and added in-line. In particular, it is preferable to add a part or all of the fine particles in-line in order to reduce the load on the filter medium.

  When the additive solution is added in-line, it is preferably dissolved in a small amount of cellulose ester in order to improve mixing with the dope. The amount of the cellulose ester is preferably 1 to 10 parts by mass, more preferably 3 to 5 parts by mass with respect to 100 parts by mass of the solvent.

  In order to perform in-line addition and mixing in the present invention, for example, an in-line mixer such as a static mixer (manufactured by Toray Engineering), SWJ (Toray static type in-tube mixer Hi-Mixer) or the like is preferably used.

(Manufacturing method of cellulose ester films (A) and (B))
Next, the manufacturing method of the cellulose-ester film (A) of this invention (B) is demonstrated.

  The cellulose ester films (A) and (B) of the present invention can be preferably used both in a film produced by a solution casting method and in a film produced by a melt casting method.

  Production of cellulose ester films (A) and (B) by the solution casting method is a step of preparing a dope by dissolving the cellulose ester and the additive in a solvent, on an endless metal support that moves the dope indefinitely. The step of casting, the step of drying the cast dope as a web, the step of peeling from the metal support, the step of stretching or maintaining the width, the step of further drying, and the step of winding the finished film are performed.

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

  The solvent used in the dope may be used alone or in combination of two or more, but it is preferable to use a mixture of a good solvent and a poor solvent of cellulose ester in terms of production efficiency, and there are many good solvents. This is preferable from the viewpoint of the solubility of the cellulose ester. The preferable range of the mixing ratio of the good solvent and the poor solvent is 70 to 98% by mass for the good solvent and 2 to 30% by mass for the poor solvent. With a good solvent and a poor solvent, what dissolve | melts the cellulose ester to be used independently is defined as a good solvent, and what poorly swells or does not melt | dissolve is defined as a poor solvent. Therefore, depending on the average acetylation degree (acetyl group substitution degree) of the cellulose ester, the good solvent and the poor solvent change. For example, when acetone is used as the solvent, the cellulose ester acetate ester (acetyl group substitution degree 2.4), cellulose Acetate propionate is a good solvent, and cellulose acetate (acetyl group substitution degree 2.8) is a poor solvent.

  The good solvent is not particularly limited, and examples thereof include organic halogen compounds such as methylene chloride, dioxolanes, acetone, methyl acetate, and methyl acetoacetate. Particularly preferred is methylene chloride or methyl acetate.

  Moreover, although a poor solvent is not specifically limited, For example, methanol, ethanol, n-butanol, cyclohexane, cyclohexanone etc. are used preferably. Moreover, it is preferable that 0.01-2 mass% of water contains in dope. Moreover, the solvent used for melt | dissolution of a cellulose ester collect | recovers the solvent removed from the film by drying at the film-forming process, and uses this again. The recovery solvent may contain trace amounts of additives added to the cellulose ester, such as plasticizers, UV absorbers, polymers, monomer components, etc., but even if these are included, they are preferably reused. Can be purified and reused if necessary.

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

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

  The heating temperature with the addition of a solvent is preferably higher from the viewpoint of the solubility of the cellulose ester, but if the heating temperature is too high, the required pressure increases and the productivity deteriorates. A preferable heating temperature is 45 to 120 ° C, more preferably 60 to 110 ° C, and still more preferably 70 ° C to 105 ° C. The pressure is adjusted so that the solvent does not boil at the set temperature.

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

  Next, this cellulose ester solution is filtered using a suitable filter medium such as filter paper. As the filter medium, it is preferable that the absolute filtration accuracy is small in order to remove insoluble matters and the like, but there is a problem that the filter medium is likely to be clogged if the absolute filtration accuracy is too small. For this reason, a filter medium with an absolute filtration accuracy of 0.008 mm or less is preferable, a filter medium with 0.001 to 0.008 mm is more preferable, and a filter medium with 0.003 to 0.006 mm is still more preferable.

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

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

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

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

  Here, the dope casting will be described.

  The metal support in the casting (casting) step preferably has a mirror-finished surface. As the metal support, a stainless steel belt or a drum whose surface is plated with a casting is preferably used. The cast width can be 1 to 4 m. The width of the cellulose ester films (A) and (B) is preferably wide, and is preferably 1.6 to 4 m in consideration of the recent polarizing plate protective film for large-sized televisions. Therefore, the cast width is inevitably wide, and the draw ratio is in the direction of increasing the magnification.

  The surface temperature of the metal support in the casting step is −50 ° C. to a temperature lower than the boiling point of the solvent, and a higher temperature is preferable because the web can be dried faster. May deteriorate. A preferable support body temperature is 0-40 degreeC, and 5-30 degreeC is still more preferable. Alternatively, it is also a preferable method that the web is gelled by cooling and peeled from the drum in a state containing a large amount of residual solvent. The method for controlling the temperature of the metal support is not particularly limited, and there are a method of blowing hot air or cold air, and a method of contacting hot water with the back side of the metal support. It is preferable to use warm water because heat transfer is performed efficiently, so that the time until the temperature of the metal support becomes constant is short. When warm air is used, wind at a temperature higher than the target temperature may be used.

  In order for the cellulose ester films (A) and (B) to exhibit good flatness, the residual solvent amount when peeling the web from the metal support is preferably 10 to 150 mass%, more preferably 20 to 40 mass%. % Or 60 to 130% by mass, particularly preferably 20 to 30% by mass or 70 to 120% by mass.

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

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

  In the drying step of the cellulose ester films (A) and (B), it is preferable that the web is peeled off from the metal support and further dried to make the residual solvent amount 1% by mass or less, more preferably 0. It is 1 mass% or less, Most preferably, it is 0-0.01 mass% or less.

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

  In order to produce the cellulose ester films (A) and (B) of the present invention, the web is stretched in the conveying direction (MD direction) where the amount of residual solvent of the web immediately after peeling from the metal support is large, and further, both ends of the web. It is particularly preferable to perform stretching in a direction (TD direction) perpendicular to the transport direction by a tenter system that grips the clip with a clip or the like.

  In order to stretch in the MD direction immediately after peeling, it is preferable to peel at a peeling tension of 210 N / m or more, particularly preferably 220 to 300 N / m.

  The means for drying the web is not particularly limited, and can be generally performed with hot air, infrared rays, a heating roll, microwave, or the like, but it is preferably performed with hot air in terms of simplicity.

  The drying temperature in the web drying step is preferably 90 ° C to 200 ° C, more preferably 110 ° C to 160 ° C. The drying temperature is preferably increased stepwise.

  Although preferable drying time is based also on drying temperature, 5 minutes-60 minutes are preferable and 10 minutes-30 minutes are more preferable.

  Although the film thickness of a cellulose-ester film (A) and (B) is not specifically limited, 10-200 micrometers is used. In particular, the film thickness is particularly preferably 10 to 100 μm. More preferably, it is 20-80 micrometers.

(Stretching operation, refractive index control)
The cellulose ester film (A) of the present invention preferably has a retardation value Ro represented by the following formula of 0 to 200 nm and Rt of 70 to 400 nm, and the cellulose ester film (B) is represented by the following formula. It is preferable that the retardation value Ro is 0 ≦ Ro ≦ 10 nm and Rt is −20 nm ≦ Rt ≦ 20 nm.

Formula (i) Ro = (nx−ny) × d
Formula (ii) Rt = ((nx + ny) / 2−nz) × d
(In the formula, Ro is the retardation value in the film plane, Rt is the retardation value in the film thickness direction, nx is the refractive index in the slow axis direction in the film plane, ny is the refractive index in the fast axis direction in the film plane, (nz represents the refractive index in the thickness direction of the film, and d represents the thickness (nm) of the film.)
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).

  In order to obtain the retardation values Ro and Rt, it is preferable that the cellulose ester film has the structure of the present invention and further the refractive index is controlled by a stretching operation.

  For example, the film can be stretched sequentially or simultaneously with respect to the MD direction and the TD direction of the film.

  The draw ratios in the biaxial directions perpendicular to each other are preferably 1.07 to 2.0 times in the MD direction and 1.07 to 2.0 times in the TD direction, respectively. It is preferable to carry out in the range of 1.07 to 1.5 times and 1.05 to 2.0 times in the TD direction.

  There is no particular limitation on the method of stretching the web. For example, a method in which peripheral speed differences are applied to a plurality of rolls and a roll peripheral speed difference is used to stretch in the MD direction, both ends of the web are fixed with clips and pins, and the distance between the clips and pins is increased in the traveling direction And a method of stretching in the MD direction, a method of stretching in the transverse direction and stretching in the TD direction, a method of stretching in the MD / TD direction simultaneously and stretching in both the MD / TD directions, and the like. Of course, these methods may be used in combination. In the case of the so-called tenter method, driving the clip portion by the linear drive method is preferable because smooth stretching can be performed and the risk of breakage and the like can be reduced.

  It is preferable to perform the width maintenance or the transverse stretching in the film forming process by a tenter, and it may be a pin tenter or a clip tenter.

  The film transport tension in the film forming process such as in the tenter depends on the temperature, but is preferably 120 N / m to 200 N / m, and more preferably 140 N / m to 200 N / m. 140 N / m to 160 N / m is most preferable.

  When stretching, assuming that the glass transition temperature of the film is Tg, the film is heated in the range of (Tg-30) to (Tg + 100) ° C., more preferably (Tg-20) to (Tg + 80) ° C., and MD direction or TD direction. It is preferable to stretch the film.

  The Tg of the cellulose ester films (A) and (B) varies depending on the material type constituting the film and the ratio of the constituting materials. In the application of the present invention, the Tg when the film is dried is preferably 110 ° C. or higher, more preferably 120 ° C. or higher. This is because when the cellulose ester films (A) and (B) are used in the liquid crystal display device, if the Tg of the film is lower than the above, due to the influence of the temperature and humidity of the use environment and the heat of the backlight, The orientation state of the fixed molecules is affected, and the possibility that the retardation value and the dimensional stability and shape as a film are greatly changed is increased. In addition, the shape of the film may not be maintained. Conversely, if the Tg of the film is too high, it becomes difficult to produce because it approaches the decomposition temperature of the film constituting material, and the presence of a volatile component or coloring may occur due to the decomposition of the material itself used when forming a film. Accordingly, the glass transition temperature is preferably 180 ° C. or lower, more preferably 150 ° C. or lower. At this time, the Tg of the film can be determined by the method described in JIS K7121.

  In the present invention, the temperature during stretching is not particularly limited, but is preferably 150 ° C. or higher because the haze stability is further improved.

  The cellulose ester films (A) and (B) are preferably heat-set after stretching, but the heat-setting is higher than the final TD direction stretching temperature and usually within a temperature range of Tg-20 ° C. or less. It is preferable to heat fix for ~ 300 seconds. Under the present circumstances, it is preferable to heat-fix, heating up sequentially in the range from which a temperature difference is set to 1-100 degreeC in the area | region divided into 2 or more.

  The heat-set film is usually cooled to Tg or less, and clip holding portions at both ends of the film are cut and wound. At this time, it is preferable to perform a relaxation treatment of 0.1 to 10% in the TD direction and / or the MD direction within a temperature range not higher than the final heat setting temperature and not lower than Tg. In addition, it is preferable that the cooling is gradually performed from the final heat setting temperature to Tg at a cooling rate of 100 ° C. or less per second. Means for cooling and relaxation treatment are not particularly limited, and can be performed by a conventionally known means. In particular, it is preferable to carry out these treatments while sequentially cooling in a plurality of temperature ranges from the viewpoint of improving the dimensional stability of the film. The cooling rate is a value obtained by (T1-Tg) / t, where T1 is the final heat setting temperature and t is the time until the film reaches Tg from the final heat setting temperature.

  More optimal conditions of these heat setting conditions, cooling, and relaxation treatment conditions vary depending on the type of additives such as cellulose ester and plasticizer constituting the film, so the physical properties of the obtained biaxially stretched film are measured and preferable characteristics are obtained. What is necessary is just to determine by adjusting suitably so that it may have.

  When the slow axis or the fast axis of the cellulose ester films (A) and (B) of the present invention are present in the film plane and the angle formed with the film forming direction is θ1, θ1 is −1 ° or more and + 1 ° or less. It is preferable that it is −0.5 ° or more and + 0.5 ° or less. This θ1 can be defined as an orientation angle, and θ1 can be measured using an automatic birefringence meter KOBRA-21ADH (Oji Scientific Instruments). Each of θ1 satisfying the above relationship can contribute to obtaining high luminance in a display image, suppressing or preventing light leakage, and contributing to obtaining faithful color reproduction in a color liquid crystal display device.

<Physical properties>
The moisture permeability of the cellulose ester films (A) and (B) is preferably 10 to 1200 g / m ² · 24 h at 40 ° C. and 90% RH, more preferably 20 to 1000 g / m ² · 24 h, and 20 to 850 g / m. ² · 24h is particularly preferable. The moisture permeability can be measured according to the method described in JIS Z 0208.

  The cellulose ester films (A) and (B) preferably have a breaking elongation of 10 to 80%, more preferably 20 to 50%.

  The visible light transmittance of the cellulose ester films (A) and (B) is preferably 90% or more, and more preferably 93% or more.

  As described above, the haze of the cellulose ester films (A) and (B) is preferably less than 1%, particularly preferably 0 to 0.1%.

(Curable resin layer (hard coat layer))
The cellulose ester film (A) of the present invention preferably further has a curable resin layer. This curable resin layer exhibits an improvement effect not only on the surface hardness but also on brittleness, particularly flex resistance.

  The curable resin layer may be a single layer, or may be two or more layers depending on the degree of use. From the point of productivity, it is preferable that it is 1 layer or more and 4 layers or less. Moreover, you may provide on both surfaces of a cellulose-ester film.

  The refractive index of the transparent resin constituting the curable resin layer is preferably 1.47 or more, more preferably 1.47 to 1.70.

  In order to make the refractive index within this range, the type and amount ratio of the transparent resin may be appropriately selected. If the refractive index is less than 1.47, it is difficult to obtain a resin with high hardness. If the refractive index is greater than 1.70, unevenness of the film tends to be noticeable.

  The refractive index of the transparent resin can be quantitatively evaluated by, for example, directly measuring with an Abbe refractometer at 23 ° C. or measuring a spectral reflection spectrum or a spectral ellipsometry.

  The curable 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.

  As the curable resin, a resin curable by heat or actinic radiation can be used, and a resin curable by a crosslinking reaction or the like by actinic radiation such as ultraviolet rays or electron beams is particularly preferable.

  Specific examples of the curable resin include an ultraviolet curable urethane acrylate 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. The ultraviolet curable 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 Unidic 17-806 (Dainippon Ink Co., Ltd.) and 1 part Coronate L (Nihon Polyurethane Co., Ltd.) is 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 its derivatives, 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.

  As acrylate resins, methyl acrylate, ethyl acrylate, butyl acrylate, benzyl acrylate, cyclohexyl acrylate, ethylene glycol diacrylate, propylene glycol diacrylate, divinylbenzene, 1,4-cyclohexane diacrylate, 1,4-cyclohexyl dimethyl adiacrylate , Trimethylolpropane triacrylate, pentaerythritol tetraacrylic ester and the like.

  As these commercial products, Adekaoptomer KR / BY series: KR-400, KR-410, KR-550, KR-566, KR-567, BY-320B (manufactured by Asahi Denka Co., Ltd.); -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.); Seika Beam PHC2210 (S), PHC X-9 (K-3), PHC2213, DP-10, DP-20, DP -30, P1000, P1100, P1200, P1300, P1400, P1500, P1600, SCR900 (manufactured by Dainichi Seika Kogyo Co., Ltd.); KRM7033, KRM703 , KRM7130, KRM7131, UVECRYL29201, UVECRYL29202 (manufactured by Daicel UC Corporation); RC-5015, RC-5016, RC-5020, RC-5031, RC-5100, RC-5102, RC-5120, RC-5122 RC-5152, RC-5171, RC-5180, RC-5181 (Dainippon Ink Chemical Co., Ltd.); 340 clear (manufactured by China Paint Co., Ltd.); Sunrad H-601, RC-750, RC-700, RC-600, RC-500, RC-611, RC-612 (manufactured by Sanyo Chemical Industries); SP -1509, SP-1507 (manufactured by Showa Polymer Co., Ltd.); RCC-15C (manufactured by Grace Japan Co., Ltd.), Aronix M-6100, M-8030, M-8060 (manufactured by Toagosei Co., Ltd.), NK hard B-420, NK ester A-DOG, NK ester A-IBD-2E (manufactured by Shin-Nakamura Chemical Co., Ltd.) and the like can be appropriately selected and used.

  Other examples include trimethylolpropane triacrylate, ditrimethylolpropane tetraacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, dioxane glycol acrylate, ethoxylated acrylate, alkyl-modified dipentaerythritol pentaacrylate, etc. Can be mentioned.

(Method for producing cured resin layer)
The cured resin layer is coated by applying a coating composition for forming the cured resin layer on the acrylic-containing resin film using a known method such as a gravure coater, dip coater, reverse coater, wire bar coater, die coater, and inkjet method. Then, it is preferable to heat-dry and to perform UV curing treatment.

  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 0.1-30 micrometers, Preferably it is 1-20 micrometers. Within this range, lack of hardness, deterioration of curling and brittleness, and deterioration of workability are prevented.

  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.

  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.

(Antireflection layer)
In the cellulose ester film (A), it is also preferable to further provide the following antireflection layer on the cured resin layer.

  The antireflection layer is preferably laminated in consideration of the refractive index, the film thickness, the number of layers, the layer order, and the like so that the reflectance is reduced by optical interference. Anti-reflective layer is composed of a low refractive index layer having a lower refractive index than the support, or a combination of a high refractive index layer and a low refractive index layer having a higher refractive index than the support. Is preferable from the viewpoint of obtaining more. Particularly preferably, it is an antireflection layer composed of two or more refractive index layers, in which two layers having different refractive indexes are laminated in the order of high refractive index layer / low refractive index layer from the support side. Used. Further, three layers having different refractive indexes from the support side are divided into a medium refractive index layer (a layer having a higher refractive index than the support and a lower refractive index than the high refractive index layer) / high refractive index layer / low refractive index layer. A layer laminated in order is also preferably used, and an antireflection layer having a layer structure of four or more layers in which two or more high refractive index layers and two or more low refractive index layers are alternately laminated is also preferably used.

(Low refractive index layer)
The low refractive index layer preferably contains silica-based fine particles, and the refractive index is lower than the refractive index of the film substrate as a support, and is 1.30 to 1.45 at 23 ° C. and a wavelength of 550 nm. A range is preferable.

  An antireflection film in which a low refractive index layer is laminated directly or via another layer on the cured resin layer is particularly preferable because of excellent adhesion and chemical resistance after a weather resistance test.

  The film thickness of the low refractive index layer is preferably 5 nm to 0.5 μm, more preferably 10 nm to 0.3 μm, and most preferably 30 nm to 0.2 μm.

  The composition for forming a low refractive index layer preferably contains at least one kind of particles having an outer shell layer and porous or hollow inside as silica-based fine particles. In particular, the particles having the outer shell layer and having a porous or hollow interior are preferably hollow silica-based fine particles.

  The composition for forming a low refractive index layer may contain an organosilicon compound represented by the following general formula (OSi-1) or a hydrolyzate thereof, or a polycondensate thereof.

General formula (OSi-1): Si (OR) ₄
In the organic silicon compound represented by the general formula, R represents an alkyl group having 1 to 4 carbon atoms. Specifically, tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane and the like are preferably used.

  In addition, a silane coupling agent, a curing agent, a surfactant and the like may be added as necessary.

(Hollow silica fine particles)
The hollow silica-based fine particles are (I) composite particles comprising porous particles and a coating layer provided on the surface of the porous particles, or (II) having cavities inside, and the contents are solvent, gas or porous It is a hollow particle filled with a porous material. Note that the low refractive index layer only needs to contain either (I) composite particles or (II) hollow particles, or both.

  Note that the cavity particles are particles having a cavity inside, and the cavity is covered with a coating layer (also referred to as a particle wall). The cavity is filled with contents such as a solvent, a gas, or a porous material used at the time of preparation. It is desirable that the average particle size of such hollow fine particles is in the range of 5 to 300 nm, preferably 10 to 200 nm. The average particle diameter of the hollow fine particles to be used is desirably 3/2 to 1/10, preferably 2/3 to 1/10, of the average film thickness of the low refractive index layer to be formed. These hollow fine particles are preferably used in a state of being dispersed in an appropriate medium in order to form a low refractive index layer. As the dispersion medium, water, alcohol (for example, methanol, ethanol, isopropyl alcohol) and ketone (for example, methyl ethyl ketone, methyl isobutyl ketone), ketone alcohol (for example, diacetone alcohol), or a mixed solvent containing these is preferable.

  The thickness of the coating layer of the composite particles or the thickness of the particle walls of the hollow particles is desirably in the range of 1 to 20 nm, preferably 2 to 15 nm. In the case of composite particles, if the thickness of the coating layer is less than 1 nm, the particles may not be completely covered, and it is easy to use a silicate monomer or oligomer having a low polymerization degree, which is a coating liquid component described later. In some cases, the refractive index of the particles is increased by entering the voids inside the composite particles, and the effect of low refractive index may not be sufficiently obtained. When the thickness of the coating layer exceeds 20 nm, the silicic acid monomer and oligomer do not enter the inside, but the porosity (pore volume) of the composite particles is lowered and the effect of low refractive index is sufficiently obtained. It may not be possible. In the case of hollow particles, if the particle wall thickness is less than 1 nm, the particle shape may not be maintained, and even if the thickness exceeds 20 nm, the effect of low refractive index may not be sufficiently exhibited. .

The coating layer of the composite particles or the particle wall of the hollow particles is preferably composed mainly of silica. Moreover, components other than silica may be contained, and specifically, Al ₂ O ₃ , B ₂ O ₃ , TiO ₂ , ZrO ₂ , SnO ₂ , CeO ₂ , P ₂ O ₃ , Sb ₂ O _3. , MoO ₃ , ZnO ₂ , WO ₃ and the like. Examples of the porous particles constituting the composite particles include those made of silica, those made of silica and an inorganic compound other than silica, and those made of CaF ₂ , NaF, NaAlF ₆ , MgF, and the like. Among these, porous particles made of a composite oxide of silica and an inorganic compound other than silica are particularly preferable. Examples of inorganic compounds other than silica include Al ₂ O ₃ , B ₂ O ₃ , TiO ₂ , ZrO ₂ , SnO ₂ , CeO ₂ , P ₂ O ₃ , Sb ₂ O ₃ , MoO ₃ , ZnO ₂ and WO _3. 1 type or 2 types or more can be mentioned. In such porous particles, the molar ratio MOX / SiO ₂ when the silica is represented by SiO ₂ and the inorganic compound other than silica is represented by oxide (MOX) is 0.0001 to 1.0, preferably It is desirable to be in the range of 0.001 to 0.3. It is difficult to obtain a porous particle having a molar ratio MOX / SiO ₂ of less than 0.0001. Even if it is obtained, particles having a small pore volume and a low refractive index cannot be obtained. Further, when the molar ratio MOX / SiO _{2 of} the porous particles exceeds 1.0, the ratio of silica decreases, so that the pore volume increases and it may be difficult to obtain a material having a lower refractive index. .

  The pore volume of such porous particles is desirably in the range of 0.1 to 1.5 ml / g, preferably 0.2 to 1.5 ml / g. If the pore volume is less than 0.1 ml / g, particles having a sufficiently reduced refractive index cannot be obtained. If the pore volume exceeds 1.5 ml / g, the strength of the fine particles is lowered, and the strength of the resulting coating may be lowered. is there.

  In addition, the pore volume of such porous particles can be determined by a mercury intrusion method. Examples of the contents of the hollow particles include a solvent, a gas, and a porous substance used at the time of preparing the particles. The solvent may contain an unreacted particle precursor used when preparing the hollow particles, the catalyst used, and the like. Moreover, what consists of the compound illustrated by the said porous particle as a porous substance is mentioned. These contents may be composed of a single component or may be a mixture of a plurality of components.

  As a method for producing such hollow fine particles, for example, the method for preparing composite oxide colloidal particles disclosed in paragraphs [0010] to [0033] of JP-A-7-133105 is suitably employed. Specifically, when the composite particles are composed of silica and an inorganic compound other than silica, hollow fine particles are produced from the following first to third steps.

First Step: Preparation of Porous Particle Precursor In the first step, an alkali aqueous solution of a silica raw material and an inorganic compound raw material other than silica is separately prepared in advance, or a silica raw material and an inorganic compound raw material other than silica are prepared in advance. A mixed aqueous solution is prepared, and this aqueous solution is gradually added to an aqueous alkaline solution having a pH of 10 or more while stirring according to the composite ratio of the target composite oxide to prepare a porous particle precursor.

  As the silica raw material, alkali metal, ammonium or organic base silicate is used. Sodium silicate (water glass) or potassium silicate is used as the alkali metal silicate. Examples of the organic base include quaternary ammonium salts such as tetraethylammonium salt, and amines such as monoethanolamine, diethanolamine, and triethanolamine. The ammonium silicate or the organic base silicate includes an alkaline solution obtained by adding ammonia, a quaternary ammonium hydroxide, an amine compound or the like to a silicic acid solution.

  In addition, alkali-soluble inorganic compounds are used as raw materials for inorganic compounds other than silica. Specifically, an oxo acid of an element selected from Al, B, Ti, Zr, Sn, Ce, P, Sb, Mo, Zn, W, etc., an alkali metal salt or alkaline earth metal salt of the oxo acid, ammonium And salts and quaternary ammonium salts. More specifically, sodium aluminate, sodium tetraborate, zirconyl ammonium carbonate, potassium antimonate, potassium stannate, sodium aluminosilicate, sodium molybdate, cerium ammonium nitrate, and sodium phosphate are suitable.

Although the pH value of the mixed aqueous solution changes simultaneously with the addition of these aqueous solutions, an operation for controlling the pH value within a predetermined range is not particularly required. The aqueous solution finally has a pH value determined by the type of inorganic oxide and the mixing ratio thereof. There is no restriction | limiting in particular in the addition rate of the aqueous solution at this time. Further, in the production of composite oxide particles, a dispersion of seed particles can be used as a starting material. The seed particles are not particularly limited, but inorganic oxides such as SiO ₂ , Al ₂ O ₃ , TiO ₂ or ZrO ₂ or fine particles of these composite oxides are used. Usually, these sols are used. Can do. Furthermore, the porous particle precursor dispersion obtained by the above production method may be used as a seed particle dispersion. When using a seed particle dispersion, the pH of the seed particle dispersion is adjusted to 10 or higher, and then an aqueous solution of the compound is added to the above-mentioned alkaline aqueous solution while stirring. Also in this case, it is not always necessary to control the pH of the dispersion. When seed particles are used in this way, it is easy to control the particle size of the porous particles to be prepared, and particles with uniform particle sizes can be obtained.

  The silica raw material and the inorganic compound raw material described above have high solubility on the alkali side. However, when both are mixed in this highly soluble pH region, the solubility of oxo acid ions such as silicate ions and aluminate ions decreases, and these composites precipitate and grow into fine particles, or seed particles. It grows on the top and particle growth occurs. Therefore, it is not always necessary to perform pH control as in the conventional method for precipitation and growth of fine particles.

The composite ratio of silica and inorganic compound other than silica in the first step is calculated by converting the inorganic compound to silica into an oxide (MOX), and the molar ratio of MOX / SiO ₂ is 0.05 to 2.0, preferably It is desirable to be within the range of 0.2 to 2.0. Within this range, the pore volume of the porous particles increases as the proportion of silica decreases. However, even when the molar ratio exceeds 2.0, the pore volume of the porous particles hardly increases. On the other hand, when the molar ratio is less than 0.05, the pore volume becomes small. When preparing the hollow particles, the molar ratio of MOX / SiO ₂ is desirably in the range of 0.25 to 2.0.

Second step: Removal of inorganic compound other than silica from porous particles In the second step, inorganic compounds other than silica (elements other than silicon and oxygen) are obtained from the porous particle precursor obtained in the first step. At least a portion is selectively removed. As a specific removal method, the inorganic compound in the porous particle precursor is dissolved and removed using a mineral acid or an organic acid, or is contacted with a cation exchange resin for ion exchange removal.

  The porous particle precursor obtained in the first step is a particle having a network structure in which silicon and an inorganic compound constituent element are bonded through oxygen. By removing the inorganic compound (elements other than silicon and oxygen) from the porous particle precursor in this way, porous particles having a larger porosity and a larger pore volume can be obtained. Further, if the amount of removing the inorganic oxide (elements other than silicon and oxygen) from the porous particle precursor is increased, the hollow particles can be prepared.

  In addition, prior to removing inorganic compounds other than silica from the porous particle precursor, fluorine-substituted, obtained by dealkalizing an alkali metal salt of silica into the porous particle precursor dispersion obtained in the first step. It is preferable to add a silicic acid solution containing an alkyl group-containing silane compound or a hydrolyzable organosilicon compound to form a silica protective film. The thickness of the silica protective film may be 0.5 to 15 nm. Even if the silica protective film is formed, the protective film in this step is porous and thin, so that it is possible to remove inorganic compounds other than silica described above from the porous particle precursor.

  By forming such a silica protective film, inorganic compounds other than silica described above can be removed from the porous particle precursor while maintaining the particle shape. Further, when forming the silica coating layer described later, the pores of the porous particles are not blocked by the coating layer, and therefore the silica coating layer described later is formed without reducing the pore volume. Can do. Note that when the amount of the inorganic compound to be removed is small, the particles are not broken, and thus it is not always necessary to form a protective film.

  When preparing hollow particles, it is desirable to form this silica protective film. When preparing the hollow particles, the inorganic compound is removed to obtain a hollow particle precursor composed of a silica protective film, a solvent in the silica protective film, and an undissolved porous solid content. When a coating layer to be described later is formed on the precursor, the formed coating layer becomes a particle wall to form hollow particles.

The amount of the silica source added for forming the silica protective film is preferably small as long as the particle shape can be maintained. If the amount of the silica source is too large, the silica protective film becomes too thick, and it may be difficult to remove inorganic compounds other than silica from the porous particle precursor. The hydrolyzable organosilicon compound used for forming the silica protective film includes a general formula RnSi (OR ′) _4-n [R, R ′: hydrocarbon such as alkyl group, aryl group, vinyl group, acrylic group, etc. An alkoxysilane represented by the group, n = 0, 1, 2, or 3] can be used. In particular, tetraalkoxysilanes such as fluorine-substituted tetramethoxysilane, tetraethoxysilane, and tetraisopropoxysilane are preferably used.

  As an addition method, a solution obtained by adding a small amount of alkali or acid as a catalyst to a mixed solution of these alkoxysilane, pure water, and alcohol is added to the dispersion of the porous particles, and the alkoxysilane is hydrolyzed. The produced silicic acid polymer is deposited on the surface of the inorganic oxide particles. At this time, alkoxysilane, alcohol, and catalyst may be simultaneously added to the dispersion. As the alkali catalyst, ammonia, an alkali metal hydroxide, or an amine can be used. As the acid catalyst, various inorganic acids and organic acids can be used.

  When the dispersion medium of the porous particle precursor is water alone or when the ratio of water to the organic solvent is high, a silica protective film can be formed using a silicic acid solution. When a silicic acid solution is used, a predetermined amount of the silicic acid solution is added to the dispersion, and at the same time an alkali is added to deposit the silicic acid solution on the surface of the porous particles. In addition, you may produce a silica protective film together using a silicic acid liquid and the said alkoxysilane.

Third step: Formation of silica coating layer In the third step, the porous particle dispersion prepared in the second step (in the case of hollow particles, the hollow particle precursor dispersion) contains a fluorine-substituted alkyl group-containing silane compound. By adding a hydrolyzable organosilicon compound or silicic acid solution, the surface of the particles is coated with a polymer such as a hydrolyzable organosilicon compound or silicic acid solution to form a silica coating layer.

Examples of the hydrolyzable organosilicon compound used for forming the silica coating layer include the general formula RnSi (OR ′) _4-n [R, R ′: alkyl group, aryl group, vinyl group, acrylic group as described above. Etc., and alkoxysilanes represented by n = 0, 1, 2, or 3] can be used. In particular, tetraalkoxysilanes such as tetramethoxysilane, tetraethoxysilane, and tetraisopropoxysilane are preferably used.

  As an addition method, a solution obtained by adding a small amount of alkali or acid as a catalyst to a mixed solution of these alkoxysilane, pure water, and alcohol is used as a dispersion of the porous particles (in the case of hollow particles, a hollow particle precursor). In addition, the silicic acid polymer produced by hydrolyzing alkoxysilane is deposited on the surface of the porous particles (in the case of hollow particles, hollow particle precursors). At this time, alkoxysilane, alcohol, and catalyst may be simultaneously added to the dispersion. As the alkali catalyst, ammonia, an alkali metal hydroxide, or an amine can be used. As the acid catalyst, various inorganic acids and organic acids can be used.

  When the dispersion medium of porous particles (in the case of hollow particles, the hollow particle precursor) is water alone or a mixed solvent with an organic solvent and the mixed solvent has a high ratio of water to the organic solvent, a silicate solution You may form a coating layer using. The silicic acid solution is an aqueous solution of a low silicic acid polymer obtained by dealkalizing an aqueous solution of an alkali metal silicate such as water glass by ion exchange treatment.

  The silicic acid solution is added to the dispersion of porous particles (in the case of hollow particles, hollow particle precursors), and at the same time, alkali is added to make the low-silicic acid polymer into porous particles (in the case of hollow particles, hollow particle precursors). ) Deposit on the surface. In addition, you may use a silicic acid liquid for the coating layer formation in combination with the said alkoxysilane. The addition amount of the organosilicon compound or silicic acid solution used for forming the coating layer only needs to be sufficient to cover the surface of the colloidal particles, and the finally obtained silica coating layer has a thickness of 1 to 20 nm. In such an amount, it is added in a dispersion of porous particles (in the case of hollow particles, a hollow particle precursor). When the silica protective film is formed, the organosilicon compound or the silicate solution is added in such an amount that the total thickness of the silica protective film and the silica coating layer is in the range of 1 to 20 nm.

  Next, the dispersion liquid of the particles on which the coating layer is formed is heat-treated. By the heat treatment, in the case of porous particles, the silica coating layer covering the surface of the porous particles is densified, and a dispersion of composite particles in which the porous particles are coated with the silica coating layer is obtained. In the case of a hollow particle precursor, the formed coating layer is densified to form hollow particle walls, and a dispersion of hollow particles having cavities filled with a solvent, gas, or porous solid content is obtained.

  The heat treatment temperature at this time is not particularly limited as long as it can close the fine pores of the silica coating layer, and is preferably in the range of 80 to 300 ° C. When the heat treatment temperature is less than 80 ° C., the fine pores of the silica coating layer may not be completely closed and densified, and the treatment time may take a long time. Further, when the heat treatment temperature exceeds 300 ° C. for a long time, fine particles may be formed, and the effect of low refractive index may not be obtained.

  The refractive index of the inorganic fine particles thus obtained is as low as less than 1.42. Such inorganic fine particles are presumed to have a low refractive index because the porosity inside the porous particles is maintained or the inside is hollow. As the hollow silica-based fine particles, those commercially available from Catalyst Kasei Co., Ltd. can be preferably used.

  The content of the hollow silica-based fine particles having an outer shell layer and porous or hollow inside is preferably 10 to 50% by mass. In order to obtain the effect of a low refractive index, the content is preferably 15% by mass or more, and when it exceeds 50% by mass, the binder component is decreased and the film strength becomes insufficient. Most preferably, it is 20-50 mass%.

  As a method of adding to the low refractive index layer, for example, a solution obtained by adding a small amount of alkali or acid as a catalyst to a mixed solution of the tetraalkoxysilane, pure water, and alcohol is added to the dispersion of the hollow silica fine particles. The silicic acid polymer produced by hydrolyzing tetraalkoxysilane is deposited on the surface of the hollow silica fine particles. At this time, tetraalkoxysilane, alcohol, and catalyst may be simultaneously added to the dispersion. As the alkali catalyst, ammonia, an alkali metal hydroxide, or an amine can be used. As the acid catalyst, various inorganic acids and organic acids can be used.

  Silica-based fine particles may be those produced by the production method described in WO2007 / 099814.

  The low refractive index layer may contain a fluorine-substituted alkyl group-containing silane compound represented by the following general formula (OSi-2).

  The fluorine-substituted alkyl group-containing silane compound represented by the general formula (OSi-2) will be described.

In the formula, R ^{1 to} R ⁶ are alkyl groups having 1 to 16 carbon atoms, preferably 1 to 4 carbon atoms, halogenated alkyl groups having 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms, and 6 to 12 carbon atoms, preferably 6 carbon atoms. 10 to 10 aryl groups, 7 to 14 carbon atoms, preferably 7 to 12 alkylaryl groups, arylalkyl groups, 2 to 8 carbon atoms, preferably 2 to 6 alkenyl groups, or 1 to 6 carbon atoms, preferably 1 to 3 alkoxy groups, a hydrogen atom or a halogen atom.

Rf represents-(CaHbFc)-, a is an integer of 1 to 12, b + c is 2a, b is an integer of 0 to 24, and c is an integer of 0 to 24. Such Rf is preferably a group having a fluoroalkylene group and an alkylene group. Specifically, examples of such fluorine-containing silicone compounds include (MeO) ₃ SiC ₂ H ₄ C ₂ F ₄ C ₂ H ₄ Si (MeO) ₃ , (MeO) ₃ SiC ₂ H ₄ C ₄ F ₈ C _{2 H 4 Si (MeO) 3} , (MeO) 3 SiC 2 H 4 C 6 F 12 C 2 H 4 Si (MeO) 3, (H 5 C 2 O) 3 SiC 2 H 4 C 4 F 8 C 2 H _{4 Si (OC 2 H 5)} 3, include methoxy disilane compound or the like represented by _{(H 5 C 2 O) 3} SiC 2 H 4 C 6 F 12 C 2 H 4 Si (OC 2 H 5) 3.

  If the fluorine-containing alkyl group-containing silane compound is included as a binder, the transparent film itself is hydrophobic, so the transparent film is not sufficiently densified and is porous or cracked. Even if it has a void or a void, entry into the transparent film by chemicals such as moisture, acid and alkali is suppressed. Furthermore, fine particles such as metals contained in the conductive layer which is the substrate surface or the lower layer do not react with chemicals such as moisture, acid and alkali. For this reason, such a transparent film has excellent chemical resistance.

  In addition, when a fluorine-substituted alkyl group-containing silane compound is included as a binder, not only the hydrophobic property but also the slipperiness (low contact resistance) is obtained, and thus a transparent film having excellent scratch strength can be obtained. Can do. Further, when the binder contains a fluorine-substituted alkyl group-containing silane compound having such a structural unit, when the conductive layer is formed in the lower layer, the shrinkage rate of the binder is equivalent to that of the conductive layer. Therefore, it is possible to form a transparent film having excellent adhesion to the conductive layer. Furthermore, when the transparent film is heat-treated, the conductive layer is not peeled off due to the difference in shrinkage rate, and a portion having no electrical contact is not generated in the transparent conductive layer. For this reason, sufficient electroconductivity can be maintained as a whole film.

  A transparent film containing a fluorine-substituted alkyl group-containing silane compound and hollow silica-based fine particles having the outer shell layer and being porous or hollow inside has high scratch strength and is evaluated by eraser strength or nail strength. The film strength is high, the pencil hardness is high, and a transparent film excellent in strength can be formed.

  The low refractive index layer may contain a silane coupling agent. Silane coupling agents include methyltrimethoxysilane, methyltriethoxysilane, methyltrimethoxyethoxysilane, methyltriacetoxysilane, methyltributoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, vinyltrimethoxysilane, vinyltrimethoxysilane. Ethoxysilane, vinyltriacetoxysilane, vinyltrimethoxyethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, phenyltriacetoxysilane, γ-chloropropyltrimethoxysilane, γ-chloropropyltriethoxysilane, γ-chloropropyltri Acetoxysilane, 3,3,3-trifluoropropyltrimethoxysilane, γ-glycidyloxypropyltrimethoxysilane, γ-glycidyloxypropyltri Ethoxysilane, γ- (β-glycidyloxyethoxy) propyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltriethoxysilane, γ- Acryloyloxypropyltrimethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, N- Examples include β- (aminoethyl) -γ-aminopropyltrimethoxysilane and β-cyanoethyltriethoxysilane.

  Examples of silane coupling agents having a disubstituted alkyl group with respect to silicon include dimethyldimethoxysilane, phenylmethyldimethoxysilane, dimethyldiethoxysilane, phenylmethyldiethoxysilane, and γ-glycidyloxypropylmethyldiethoxysilane. Γ-glycidyloxypropylmethyldimethoxysilane, γ-glycidyloxypropylphenyldiethoxysilane, γ-chloropropylmethyldiethoxysilane, dimethyldiacetoxysilane, γ-acryloyloxypropylmethyldimethoxysilane, γ-acryloyloxypropylmethyldi Ethoxysilane, γ-methacryloyloxypropylmethyldimethoxysilane, γ-methacryloyloxypropylmethyldiethoxysilane, γ-mercaptopropylmethyldimeth Shishiran, .gamma.-mercaptopropyl methyl diethoxy silane, .gamma.-aminopropyl methyl dimethoxy silane, .gamma.-aminopropyl methyl diethoxy silane, methyl vinyl dimethoxy silane, and methyl vinyl diethoxy silane.

  Among these, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, vinyltrimethoxyethoxysilane, γ-acryloyloxypropyltrimethoxysilane and γ-methacryloyloxypropyltrimethoxysilane having a double bond in the molecule. Γ-acryloyloxypropylmethyldimethoxysilane, γ-acryloyloxypropylmethyldiethoxysilane, γ-methacryloyloxypropylmethyldimethoxysilane, and γ-methacryloyloxypropylmethyldiethoxy having a disubstituted alkyl group with respect to silicon Silane, methylvinyldimethoxysilane and methylvinyldiethoxysilane are preferred, and γ-acryloyloxypropyltrimethoxysilane and γ-methacryloyloxyp Particularly preferred are propyltrimethoxysilane, γ-acryloyloxypropylmethyldimethoxysilane, γ-acryloyloxypropylmethyldiethoxysilane, γ-methacryloyloxypropylmethyldimethoxysilane and γ-methacryloyloxypropylmethyldiethoxysilane.

  Two or more coupling agents may be used in combination. In addition to the silane coupling agents shown above, other silane coupling agents may be used. Other silane coupling agents include alkyl esters of orthosilicate (eg, methyl orthosilicate, ethyl orthosilicate, n-propyl orthosilicate, i-propyl orthosilicate, n-butyl orthosilicate, sec-butyl orthosilicate, orthosilicate). Acid t-butyl) and its hydrolyzate.

The low refractive index layer may contain a silicon compound represented by CF ₃ (CF ₂ ) nCH ₂ CH ₂ Si (OR ₁ ) ₃ . (Wherein R ₁ represents an alkyl group having 1 to 5 carbon atoms, and n represents an integer of 0 to 12). Specific compounds include trifluoropropyltrimethoxysilane, trifluoro Examples include propyltriethoxysilane, tridecafluorooctyltrimethoxysilane, tridecafluorooctyltriethoxysilane, heptadecafluorodecyltrimethoxysilane, heptadecafluorodecyltriethoxysilane, and these are used alone or in combination of two or more. Can be used.

_{Moreover, H 2 NCONH (CH) m} Si (OR 2) a terminal position represented by ₃ may contain a silicon compound having an ureido group _(H 2 NCONH-). (In the formula, R ₂ represents an alkyl group having 1 to 5 carbon atoms, and m represents an integer of 1 to 5.) Specific compounds include γ-ureidopropyltrimethoxysilane, γ- Examples thereof include ureidopropyltriethoxysilane and γ-ureidopropyltripropoxysilane. Among these, γ-ureidopropyltrimethoxysilane, γ-ureidopropyltriethoxysilane, and the like are particularly preferable.

  In addition, the low refractive index layer can use, for example, polyvinyl alcohol, polyoxyethylene, polymethyl methacrylate, polymethyl acrylate, fluoroacrylate, diacetyl cellulose, triacetyl cellulose, nitrocellulose, polyester, alkyd resin, etc. as a binder. .

  In addition, the low refractive index layer includes, for example, polyvinyl alcohol, polyoxyethylene, polymethyl methacrylate, polymethyl acrylate, fluoroacrylate, diacetyl cellulose, triacetyl cellulose, nitrocellulose, polyester, and alkyd resin as a binder.

  The low refractive index layer preferably contains 5 to 80% by mass of binder as a whole. The binder has a function of adhering the hollow silica-based fine particles and maintaining the structure of the low refractive index layer including voids. The usage-amount of a binder is suitably adjusted so that the intensity | strength of a low refractive index layer can be maintained, without filling a space | gap.

(solvent)
The low refractive index layer preferably contains an organic solvent. Specific examples of organic solvents include alcohols (eg, methanol, ethanol, isopropanol, butanol, benzyl alcohol), ketones (eg, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone), esters (eg, methyl acetate, ethyl acetate). , Propyl acetate, butyl acetate, methyl formate, ethyl formate, propyl formate, butyl formate), aliphatic hydrocarbons (eg, hexane, cyclohexane), halogenated hydrocarbons (eg, methylene chloride, chloroform, carbon tetrachloride), aromatic Group hydrocarbon (eg, benzene, toluene, xylene), amide (eg, dimethylformamide, dimethylacetamide, n-methylpyrrolidone), ether (eg, diethyl ether, dioxane, tetrahydrofuran), ether alcohol (eg, 1-methoxy-2-propanol). Of these, toluene, xylene, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone and butanol are particularly preferable.

  The solid content concentration in the low refractive index layer coating composition is preferably 1 to 4% by mass. By making the solid content concentration 4% by mass or less, coating unevenness is less likely to occur, and the content is 1% by mass or more. By doing so, the drying load is reduced.

(High refractive index layer)
In addition to the above-described low refractive index layer, the antireflection layer may have the following high refractive index layer.

  The high refractive index layer preferably contains metal oxide fine particles. The kind of metal oxide fine particles is not particularly limited, and Ti, Zr, Sn, Sb, Cu, Fe, Mn, Pb, Cd, As, Cr, Hg, Zn, Al, Mg, Si, P and S A metal oxide having at least one element selected from the group consisting of Al, In, Sn, Sb, Nb, a halogen element, Ta and the like is doped with a minute amount of atoms. May be. A mixture of these may also be used. In the present invention, at least one metal oxide fine particle selected from among zirconium oxide, antimony oxide, tin oxide, zinc oxide, indium-tin oxide (ITO), antimony-doped tin oxide (ATO), and zinc antimonate is used. It is particularly preferable to use it as the main component. In particular, it is preferable to contain zinc antimonate particles.

  The average particle diameter of the primary particles of these metal oxide fine particles is in the range of 10 nm to 200 nm, particularly preferably 10 to 150 nm. The average particle diameter of the metal oxide fine particles can be measured from an electron micrograph taken with a scanning electron microscope (SEM) or the like. You may measure by the particle size distribution meter etc. which utilize a dynamic light scattering method, a static light scattering method, etc. If the particle size is too small, aggregation tends to occur and the dispersibility deteriorates. If the particle size is too large, the haze is remarkably increased. The shape of the metal oxide fine particles is preferably a rice grain shape, a spherical shape, a cubic shape, a spindle shape, a needle shape, or an indefinite shape.

  Specifically, the refractive index of the high refractive index layer is higher than the refractive index of the film as the support, and is preferably in the range of 1.5 to 2.2 when measured at 23 ° C. and a wavelength of 550 nm. The means for adjusting the refractive index of the high refractive index layer is that the kind and addition amount of the metal oxide fine particles are dominant, so that the refractive index of the metal oxide fine particles is preferably 1.80 to 2.60, More preferably, it is 1.85 to 2.50.

  The metal oxide fine particles may be surface-treated with an organic compound. By modifying the surface of the metal oxide fine particles with an organic compound, the dispersion stability in an organic solvent is improved, the dispersion particle size can be easily controlled, and aggregation and sedimentation over time can be suppressed. . For this reason, the surface modification amount with a preferable organic compound is 0.1 mass%-5 mass% with respect to metal oxide particle, More preferably, it is 0.5 mass%-3 mass%. Examples of the organic compound used for the surface treatment include polyols, alkanolamines, stearic acid, silane coupling agents, and titanate coupling agents. Of these, silane coupling agents are preferred. Two or more kinds of surface treatments may be combined.

  The thickness of the high refractive index layer containing the metal oxide fine particles is preferably 5 nm to 1 μm, more preferably 10 nm to 0.2 μm, and most preferably 30 nm to 0.1 μm.

  The ratio of the metal oxide fine particles to be used and a binder such as an actinic ray curable resin to be described later varies depending on the kind of metal oxide fine particles, the particle size, etc., but the volume ratio of the former 1 to the latter 2 to the former 2 The latter one is preferable.

  The amount of the metal oxide fine particles used in the present invention is preferably 5% by mass to 85% by mass in the high refractive index layer, more preferably 10% by mass to 80% by mass, and most preferably 20% to 75% by mass. preferable. If the amount used is small, the desired refractive index and the effect of the present invention cannot be obtained, and if it is too large, the film strength deteriorates.

  The metal oxide fine particles are supplied to a coating solution for forming a high refractive index layer in a dispersion state dispersed in a medium. As a dispersion medium for metal oxide particles, it is preferable to use a liquid having a boiling point of 60 to 170 ° C. Specific examples of the dispersion solvent include water, alcohol (eg, methanol, ethanol, isopropanol, butanol, benzyl alcohol), ketone (eg, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone), ketone alcohol (eg, diacetone alcohol). , Esters (eg, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl formate, ethyl formate, propyl formate, butyl formate), aliphatic hydrocarbons (eg, hexane, cyclohexane), halogenated hydrocarbons (eg, methylene) Chloride, chloroform, carbon tetrachloride), aromatic hydrocarbons (eg, benzene, toluene, xylene), amides (eg, dimethylformamide, dimethylacetamide, n-methylpyrrolidone), ethers (eg, diethyl ether, dioxane, Tiger hydrofuran), ether alcohols (e.g., 1-methoxy-2-propanol), propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate. Of these, toluene, xylene, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone and butanol are particularly preferable.

  The metal oxide fine particles can be dispersed in the medium using a disperser. Examples of the disperser include a sand grinder mill (eg, a bead mill with pins), a high-speed impeller mill, a pebble mill, a roller mill, an attritor, and a colloid mill. A sand grinder mill and a high-speed impeller mill are particularly preferred. Further, preliminary dispersion processing may be performed. Examples of the disperser used for the preliminary dispersion treatment include a ball mill, a three-roll mill, a kneader, and an extruder. It is also preferable to contain a dispersant.

  Furthermore, metal oxide fine particles having a core / shell structure may be contained. One layer of the shell may be formed around the core, or a plurality of layers may be formed in order to further improve the light resistance. The core is preferably completely covered by the shell.

  For the core, titanium oxide (rutile type, anatase type, amorphous type, etc.), zirconium oxide, zinc oxide, cerium oxide, indium oxide doped with tin, tin oxide doped with antimony, etc. can be used. Titanium may be the main component.

  The shell is preferably formed of a metal oxide or sulfide containing an inorganic compound other than titanium oxide as a main component. For example, an inorganic compound mainly composed of silicon dioxide (silica), aluminum oxide (alumina) zirconium oxide, zinc oxide, tin oxide, antimony oxide, indium oxide, iron oxide, zinc sulfide, or the like is used. Of these, alumina, silica, and zirconia (zirconium oxide) are preferable. A mixture of these may also be used.

  The coating amount of the shell with respect to the core is 2 to 50% by mass as an average coating amount. Preferably it is 3-40 mass%, More preferably, it is 4-25 mass%. When the coating amount of the shell is large, the refractive index of the fine particles is lowered, and when the coating amount is too small, the light resistance is deteriorated. Two or more inorganic fine particles may be used in combination.

  The titanium oxide used as a core can use what was produced by the liquid phase method or the gaseous-phase method. As a method for forming the shell around the core, for example, U.S. Pat. No. 3,410,708, JP-B-58-47061, U.S. Pat. No. 2,885,366, and U.S. Pat. No. 1, British Patent No. 1,134,249, US Pat. No. 3,383,231, British Patent No. 2,629,953, No. 1,365,999, etc. Can do.

  The high refractive index layer or the low refractive index layer described above can contain a compound represented by the following general formula (CL1) or a chelate compound thereof, and can improve physical properties such as hardness.

Formula (CL1) AnMB _x-n
In the formula, M represents a metal atom, A represents a hydrolyzable functional group or a hydrocarbon group having a hydrolyzable functional group, and B represents an atomic group covalently or ionically bonded to the metal atom M. x represents the valence of the metal atom M, and n represents an integer of 2 or more and x or less.

  Examples of the hydrolyzable functional group A include halogens such as alkoxyl groups and chloro atoms, ester groups and amide groups. The metal compound belonging to the general formula (CL1) includes an alkoxide having two or more alkoxyl groups directly bonded to a metal atom, or a chelate compound thereof. Preferable metal compounds include titanium alkoxide, zirconium alkoxide, or chelate compounds thereof. Titanium alkoxide has a high reaction rate and a high refractive index and is easy to handle. However, since it has a photocatalytic action, its light resistance deteriorates when added in a large amount. Zirconium alkoxide has a high refractive index but tends to become cloudy, so care must be taken in dew point management during coating. Moreover, since titanium alkoxide has the effect of promoting the reaction of the ultraviolet curable resin and metal alkoxide, the physical properties of the coating film can be improved by adding a small amount.

  Examples of the titanium alkoxide include tetramethoxy titanium, tetraethoxy titanium, tetra-iso-propoxy titanium, tetra-n-propoxy titanium, tetra-n-butoxy titanium, tetra-sec-butoxy titanium, tetra-tert-butoxy titanium, and the like. Is mentioned.

  Examples of the zirconium alkoxide include tetramethoxy zirconium, tetraethoxy zirconium, tetra-iso-propoxy zirconium, tetra-n-propoxy zirconium, tetra-n-butoxy zirconium, tetra-sec-butoxy zirconium, tetra-tert-butoxy zirconium, and the like. Is mentioned.

  Preferred chelating agents for forming a chelate compound by coordination to a free metal compound include alkanolamines such as diethanolamine and triethanolamine, glycols such as ethylene glycol, diethylene glycol and propylene glycol, acetylacetone and acetoacetic acid. Examples thereof include ethyl and the like having a molecular weight of 10,000 or less. By using these chelating agents, it is possible to form a chelate compound that is stable against water mixing and is excellent in the effect of reinforcing the coating film.

  The addition amount of the metal compound is preferably adjusted so that the content of the metal oxide derived from the metal compound contained in the high refractive index layer is 0.3 to 5% by mass. If it is less than 0.3% by mass, the scratch resistance is insufficient, and if it exceeds 5% by mass, the light resistance tends to deteriorate.

  The high refractive index layer preferably contains an actinic ray curable resin as a binder for the metal oxide fine particles in order to improve the film formability and physical properties of the coating film. Examples of the actinic ray curable resin include monomers or oligomers having two or more functional groups that cause polymerization reaction directly by irradiation of actinic rays such as ultraviolet rays and electron beams or indirectly by the action of a photopolymerization initiator. Can be used. In the present invention, a polyol acrylate, an epoxy acrylate, a urethane acrylate, a polyester acrylate or a mixture thereof is preferable. For example, the polyfunctional acrylate compound described in the hard coat layer is preferable.

  The addition amount of the actinic ray curable resin is preferably 15% by mass or more and less than 50% by mass in the solid content in the high refractive index composition.

  In order to accelerate the curing of the actinic ray curable resin used in the present invention, the photopolymerization initiator and the acrylic compound having two or more polymerizable unsaturated bonds in the molecule are in a mass ratio of 3: 7 to 1: It is preferable to contain 9.

  Specific examples of the photopolymerization initiator include acetophenone, benzophenone, hydroxybenzophenone, Michler's ketone, α-amyloxime ester, thioxanthone, and derivatives thereof, but are not particularly limited thereto.

  Examples of the organic solvent used for coating the high refractive index layer include alcohols (for example, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, secondary butanol, tertiary butanol, pentanol, hexanol, cyclohexanol). , Benzyl alcohol, etc.), polyhydric alcohols (for example, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, butylene glycol, hexanediol, pentanediol, glycerin, hexanetriol, thio Diglycol, etc.), polyhydric alcohol ethers (eg, ethylene glycol monomethyl ether, Lenglycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, triethylene glycol monomethyl ether, triethylene glycol monoethyl Ether, ethylene glycol monophenyl ether, propylene glycol monophenyl ether, etc.), amines (for example, ethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, morpholine, N-ethylmorpholine, ether) Range amine, diethylenediamine, triethylenetetramine, tetraethylenepentamine, polyethyleneimine, pentamethyldiethylenetriamine, tetramethylpropylenediamine, etc.), amides (eg, formamide, N, N-dimethylformamide, N, N-dimethylacetamide, etc.) ), Heterocyclic rings (for example, 2-pyrrolidone, N-methyl-2-pyrrolidone, cyclohexyl pyrrolidone, 2-oxazolidone, 1,3-dimethyl-2-imidazolidinone, etc.), sulfoxides (for example, dimethyl sulfoxide, etc.) , Sulfones (e.g., sulfolane), urea, acetonitrile, acetone and the like, and alcohols, polyhydric alcohols, and polyhydric alcohol ethers are particularly preferable.

  As a coating method of the cured resin layer and the antireflection layer, a gravure coater, a dip coater, a wire bar coater, a reverse coater, an extrusion coater, or the like can be used.

(Polarizer)
The polarizing plate of the present invention and a liquid crystal display device using the same will be described.

  The polarizing plate of the present invention is a polarizing plate formed by sandwiching both surfaces of a polarizer with the cellulose ester film (A) and the cellulose ester (B) of the present invention.

  The polarizing plate can be produced by a general method. A fully saponified polyvinyl alcohol aqueous solution is used on at least one surface of a polarizer produced by subjecting the cellulose ester films (A) and (B) of the present invention to an alkali saponification treatment and immersion drawing in an iodine solution. It is preferable to stick them together.

  The liquid crystal display device of the present invention is characterized by having the polarizing plate of the present invention on at least one surface of the liquid crystal cell. The polarizing plate on the side facing the liquid crystal cell is the polarizing plate of the present invention. Alternatively, another polarizing plate may be used.

  Another polarizing plate may be, for example, a polarizing plate having a polarizer sandwiched between commercially available cellulose ester films. KC8UCR-3, KC8UCR-4, KC8UCR-5, KC4FR-1, KC8UY-HA, KC8UX-RHA (supplied by Konica Minolta Opto) are also preferably used.

  In addition, it is also preferable to use a cellulose ester film that also serves as an optical compensation film having an optically anisotropic layer formed by aligning a liquid crystal compound such as a discotic liquid crystal, for example, by the method described in JP-A-2005-275083. An optically anisotropic layer can be formed.

  A polarizer, which is a main component of a polarizing plate, is an element that allows only light of a plane of polarization in a certain direction to pass. A typical polarizer currently known is a polyvinyl alcohol-based polarizing film, which is polyvinyl alcohol. There are one in which iodine is dyed on a system film and one in which dichroic dye is 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. The film thickness of the polarizer is preferably 5 to 30 μm, particularly preferably 10 to 20 μm.

  Further, the ethylene unit content described in JP-A-2003-248123, JP-A-2003-342322, etc. is 1 to 4 mol%, the degree of polymerization is 2000 to 4000, and the degree of saponification is 99.0 to 99.99 mol%. Ethylene-modified polyvinyl alcohol is also preferably used. Among them, an ethylene-modified polyvinyl alcohol film having a hot water cutting temperature of 66 to 73 ° C. is preferably used. The difference in hot water cutting temperature between two points 5 cm away in the TD direction of the film is more preferably 1 ° C. or less in order to reduce color spots, and two points separated 1 cm in the TD direction of the film. In order to reduce color spots, it is more preferable that the difference in the hot water cutting temperature is 0.5 ° C. or less.

  A polarizer using this ethylene-modified polyvinyl alcohol film is excellent in polarization performance and durability, and has few color spots, and is particularly preferably used for a large-sized liquid crystal display device.

  The polarizer obtained as described above is usually used as a polarizing plate with a protective film bonded to both sides or one side thereof. Examples of the adhesive used for pasting include a PVA-based adhesive and a urethane-based adhesive. Among them, a PVA-based adhesive is preferably used.

(Liquid crystal display device)
By incorporating the polarizing plate of the present invention into a display device, the liquid crystal display device of the present invention having various visibility can be manufactured. In particular, it is preferably applied to a VA type (MVA type, PVA type) liquid crystal display device.

  The liquid crystal display device using the polarizing plate of the present invention is particularly effective for use in a multi-domain liquid crystal display device, more preferably a multi-domain liquid crystal display device with a birefringence mode. Can do.

  The polarizing plate of the present invention is effective in the MVA (Multi-domain Vertical Alignment) mode represented by the vertical alignment mode, in particular, the MVA mode divided into four, and the known PVA (Patterned Vertical Alignment) mode multi-domained by electrode arrangement. Can be used.

  The polarizing plate of the present invention can impart excellent front contrast even when used in a liquid crystal display device having a large screen of 30 type or more.

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

<Material used in Examples>
<Cellulose ester>
TAC-1: Triacetyl cellulose (acetyl group substitution degree: 2.89 to 2.93)
TAC-2: cellulose acetate propionate (acetyl group substitution degree 1.9, propionyl group substitution degree 0.7, total acyl group substitution degree 2.6)
<Synthesis of acrylic polymer (acrylic copolymer)>
(Synthesis of acrylic polymers 1 to 3)
A glass flask equipped with a stirrer, two dropping funnels, a gas introduction tube and a thermometer was charged with 40 g of a monomer mixture of the types and ratios described in Table 1, 3.0 g of a mercaptopropionic acid chain transfer agent and 30 g of toluene, The temperature was raised to 90 ° C. Thereafter, from one dropping funnel, 60 g of a monomer mixture of the types and ratios shown in Table 1 was dropped over 3 hours, and at the same time, 0.6 g of azobisisobutyronitrile dissolved in 14 g of toluene was added from the other funnel. The solution was added dropwise over 3 hours. Thereafter, 0.6 g of azobisisobutyronitrile dissolved in 56 g of toluene was added dropwise over 2 hours, and the reaction was further continued for 2 hours to obtain acrylic polymer 1. Subsequently, in the synthesis | combination of the acrylic polymer 1, the same synthesis | combination was performed by changing the addition amount of the mercaptopropionic acid of a chain transfer agent, and the acrylic polymers 2 and 3 were obtained.

  The weight average molecular weights of the acrylic polymers 1 to 3 were measured by the following measuring method and are shown in Table 1.

  In Table 1, MMA, HEMA, and HEA are abbreviations for the following compounds, respectively.

MMA: Methyl methacrylate HEMA: 2-hydroxyethyl methacrylate HEA: β-hydroxyethyl acrylate (molecular weight measurement)
The weight average molecular weight was measured using high performance liquid chromatography.

  The measurement conditions are as follows.

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

<Synthesis of acrylic polymers 4-8>
(Synthesis of polymer 4)
Methyl acrylate 8 parts by weight 2-hydroxyethyl acrylate 1 part by weight AIBN (α, α′-azoisobutyronitrile) 1 part by weight Toluene 30 parts by weight The above composition was synthesized by solution polymerization, the solvent was removed, and Mw 5000 Of polymer 4 was obtained.

(Synthesis of polymer 5)
Methyl acrylate 8 parts by mass 2-hydroxyethyl acrylate 1 part by mass AIBN 2 parts by mass Toluene 30 parts by mass The above composition was synthesized by solution polymerization, and the solvent was removed to obtain a polymer 5 having Mw2000.

(Synthesis of polymer 6)
Methyl acrylate 10 parts by weight AIBN 2 parts by weight Toluene 30 parts by weight The above composition was synthesized by solution polymerization, and the solvent was removed to obtain a polymer 6 having Mw2000.

(Synthesis of polymer 7)
Methyl methacrylate 8 parts by mass 2-hydroxyethyl methacrylate 1 part by mass AIBN 2 parts by mass Toluene 30 parts by mass The above composition was synthesized by solution polymerization, and the solvent was removed to obtain a polymer 7 having Mw 8000.

(Synthesis of polymer 8)
Methyl acrylate 3 parts by mass Ethyl acrylate 6 parts by mass 2-hydroxyethyl acrylate 1 part by mass AIBN 2 parts by mass Toluene 30 parts by mass The above composition was synthesized by solution polymerization, and the solvent was removed to obtain a polymer 8 having Mw2000.

<Other additives>
AsSc: sugar ester compound, acetyl saccharose BzSc: sugar ester compound, benzyl saccharose EPEG: ethylphthalyl ethyl glycolate TPP: triphenyl phosphate ATBC: acetyl tributyl citrate MA1000: methyl acrylate, Mw1000
<Production of cellulose ester films (A) and (B)>
First, a cellulose ester film A1 as a cellulose ester film (A) was produced according to the following procedure.

(Fine particle dispersion formulation)
(Silicon dioxide dispersion)
Aerosil 972V (manufactured by Nippon Aerosil Co., Ltd.) 10 parts by mass (average primary particle diameter 16 nm, apparent specific gravity 90 g / liter)
90 parts by mass of ethanol or more was stirred and mixed with a dissolver for 30 minutes, and then dispersed with Manton Gorin. 88 parts by mass of methylene chloride was added to the silicon dioxide dispersion while stirring, and the mixture was stirred and mixed for 30 minutes with a dissolver to prepare a silicon dioxide dispersion dilution. It filtered with the fine particle dispersion | distribution dilution liquid filter (Advantech Toyo Co., Ltd .: Polypropylene wind cartridge filter TCW-PPS-1N).

(Production of in-line additive solution)
Tinuvin 928 (manufactured by Ciba Japan Co., Ltd.) 15 parts by mass Methylene chloride 100 parts by mass The above was put into a hermetic container, heated, stirred and completely dissolved and filtered.

  To this was added 36 parts by mass of the silicon dioxide dispersion diluted solution with stirring, and further stirred for 30 minutes. Then, 6 parts by mass of the following cellulose triacetate was added with stirring, and the mixture was further stirred for 60 minutes. The inline additive solution was filtered with a filter (Finemet NF manufactured by Nippon Seisen Co., Ltd.). A filter medium with a nominal filtration accuracy of 20 μm was used.

(Dope composition)
Cellulose ester TAC1 (cellulose triacetate synthesized from linter cotton, degree of acetylation: 61.5%, Mw = 290000) 100 parts by mass additive a1 (acrylic copolymer: acrylic polymer 1) 5 parts by weight additive a2 (sugar (Ester compound: benzyl saccharose) 5 parts by weight Methylene chloride 430 parts by weight Ethanol 40 parts by weight The above is put into a sealed container, heated and stirred to dissolve completely, and Azumi Filter Paper No. No. 24 was used for filtration to prepare a dope solution.

  Next, the inline additive solution was filtered with an inline additive solution feeding filter (Finemet NF manufactured by Nippon Seisen Co., Ltd.). A filter medium with a nominal filtration accuracy of 20 μm was used. Add 2.5 parts by mass of the filtered inline additive to 100 parts by mass of the filtered dope and mix thoroughly with an inline mixer (Toray static type in-pipe mixer Hi-Mixer, SWJ), and then a belt casting apparatus Was cast uniformly onto a stainless steel band support at a temperature of 35 ° C. and a width of 2 m. With the stainless steel band support, the solvent was evaporated until the residual solvent amount reached 100% by mass, and the stainless steel band support was peeled off. The peeled cellulose ester film web is conveyed at 35 ° C., slitted, and then stretched 1.25 times in the TD direction (direction perpendicular to the film conveying direction) with a tenter and dried at a drying temperature of 170 ° C. It was. At this time, the residual solvent amount when starting stretching with a tenter was 20%. Then, after drying for 15 minutes while transporting the inside of a drying apparatus at 120 ° C. with a number of rolls, slitting, applying a knurling process with a width of 15 mm and a height of 10 μm at both ends of the film, winding it on a core, and a cellulose ester film A1 was obtained. The residual solvent amount of the film was less than 0.1%, the film thickness was 80 μm, the width was 2 m, and the winding length was 6000 m.

  In addition, the draw ratio of MD direction computed from the rotational speed of a stainless steel band support body and the driving speed of a tenter was 1.05 times.

  Cellulose ester films A2 to A25 described in Tables 2 and 3 except that the cellulose ester, additives a1 and a2, additives b1 and b2, stretching conditions (magnification, temperature), and film thickness were changed. And B1-20 were produced. The film thickness and product width were adjusted appropriately so that the width and film thickness during casting were adjusted to the set values.

<Evaluation>
Using the produced cellulose ester film (A) and cellulose ester film (B), the elastic modulus in the TD direction and MD direction was measured and listed in Tables 2 and 3.

(Measurement of elastic modulus)
According to ISO 527-3, the elastic modulus (MPa) is 10 points each in the TD direction and MD direction of the film at 23 ° C. and 55% RH using a tensile tester manufactured by Toyo Seiki Seisakusho Co., Ltd. A tensile test was performed, and an average value was obtained from strength data of 10% strain.

  Next, the following hard coat layer, back coat layer, and antireflection layer were provided on the cellulose ester films A1 to A25.

(Composition of hard coat layer solution)
The following were mixed and used.

Dipentaerythritol hexaacrylate monomer 60 parts by weight Dipentaerythritol hexaacrylate dimer 20 parts by weight More than dipentaerythritol hexaacrylate trimer 20 parts by weight Diethoxybenzophenone photoinitiator 4 parts by weight Silicone surface activity Agent 1 part by weight Propylene glycol monomethyl ether 75 parts by weight Methyl ethyl ketone 75 parts by weight (composition of backcoat layer solution)
The following were mixed and used.

Acetone 32 parts by weight Ethyl acetate 50 parts by weight Isopropyl alcohol 4 parts by weight Diacetylcellulose 0.5 part by weight Ultrafine silica 2% acetone dispersion 0.1 part by weight (Aerosil 200; manufactured by Nippon Aerosil Co., Ltd.)
A hard coat layer (7 μm) was applied 20 mm inside from the edge of the support, dried and irradiated with ultraviolet rays, and then the back coat layer was applied at 30 g / m ² (wet) and dried.

<Formation of multilayer antireflection layer>
On each of the hard coat layers, the following high refractive index layer coating composition 1 was applied with an extrusion coater, dried at 100 ° C. for 1 minute, and then cured by irradiation with ultraviolet rays of 0.1 J / cm ² . Further, it was thermally cured at 120 ° C. for 5 minutes, and a high refractive index layer was provided so as to have a thickness of 100 nm.

  The refractive index of this high refractive index layer was 1.89.

<High refractive index layer coating composition 1>
Isopropyl alcohol solution of metal oxide fine particles (solid content 20%, ITO particles, particle size 5 nm) 55 parts by mass Metal compound: Ti (OBu) ₄ (tetra-n-butoxytitanium) 1.3 parts by mass Ionizing radiation curable resin : Dipentaerythritol hexaacrylate 3.2 parts by mass Photopolymerization initiator: Irgacure 184 (manufactured by Ciba Japan) 0.8 parts by mass Linear dimethyl silicone-EO block copolymer (FZ-2207, Nippon Unicar Co., Ltd.) 10% propylene glycol monomethyl ether solution 1.5 parts by mass propylene glycol monomethyl ether 120 parts by mass isopropyl alcohol 240 parts by mass methyl ethyl ketone 40 parts by mass <low refractive index layer>
On each of the high refractive index layers, the following low refractive index layer coating composition 1 is applied by an extrusion coater, dried at 100 ° C. for 1 minute, and then cured by irradiation with ultraviolet rays of 0.1 J / cm ^2. The film was further heat-cured at 120 ° C. for 5 minutes, and a low refractive index layer was provided so as to have a thickness of 95 nm to produce an antireflection film. The refractive index of this low refractive index layer was 1.37.

(Preparation of low refractive index layer coating composition 1)
<Preparation of tetraethoxysilane hydrolyzate A>
Hydrolyzate A was prepared by mixing 289 g of tetraethoxysilane and 553 g of ethanol, adding 157 g of 1.6% aqueous acetic acid solution thereto, and stirring in a water bath at 25 ° C. for 30 hours.

Tetraethoxysilane hydrolyzate A 110 parts by mass Hollow silica-based fine particle dispersion (P-1 below) 30 parts by mass KBM503 (silane coupling agent, manufactured by Shin-Etsu Chemical Co., Ltd.) 4 parts by mass Linear dimethyl silicone-EO block copolymer (FZ-2207, manufactured by Nippon Unicar Co., Ltd.) 10% propylene glycol monomethyl ether solution 3 parts by mass Propylene glycol monomethyl ether 400 parts by mass Isopropyl alcohol 400 parts by mass <Preparation of hollow silica-based fine particle dispersion P-1>
A mixture of 100 g of silica sol having an average particle diameter of 5 nm and a SiO ₂ concentration of 20% by mass and 1900 g of pure water was heated to 80 ° C. The pH of this reaction mother liquor was 10.5, and 9000 g of 0.98 mass% sodium silicate aqueous solution as SiO ₂ and 9000 g of 1.02 mass% sodium aluminate aqueous solution as Al ₂ O ₃ were simultaneously added to the mother liquor. did. Meanwhile, the temperature of the reaction solution was kept at 80 ° C. The pH of the reaction solution rose to 12.5 immediately after the addition and hardly changed thereafter. After completion of the addition, the reaction solution was cooled to room temperature and washed with an ultrafiltration membrane to prepare a SiO ₂ .Al ₂ O ₃ core particle dispersion having a solid content concentration of 20% by mass. (Step (a)) 1700 g of pure water was added to 500 g of this core particle dispersion and heated to 98 ° C., and the sodium silicate aqueous solution was dealkalized with a cation exchange resin while maintaining this temperature. A dispersion of core particles in which 3000 g of a silicic acid solution (SiO ₂ concentration of 3.5% by mass) was added to form a first silica coating layer was obtained. (Process (b))
Next, 1125 g of pure water is added to 500 g of the core particle dispersion liquid that has been washed with an ultrafiltration membrane to form a first silica coating layer having a solid concentration of 13% by mass, and concentrated hydrochloric acid (35.5%) is further added dropwise. The pH was adjusted to 1.0 and dealumination was performed. Next, the aluminum salt dissolved in the ultrafiltration membrane is separated while adding 10 L of hydrochloric acid aqueous solution of pH 3 and 5 L of pure water, and SiO ₂ · Al in which some of the constituent components of the core particles forming the first silica coating layer are removed. A dispersion of ₂ O ₃ porous particles was prepared (step (c)).

A mixture of 1500 g of the above porous particle dispersion, 500 g of pure water, 1,750 g of ethanol, and 626 g of 28% ammonia water is heated to 35 ° C., and then 104 g of ethyl silicate (SiO ₂ 28 mass%) is added, The surface of the porous particles on which the first silica coating layer was formed was coated with a hydrolyzed polycondensate of ethyl silicate to form a second silica coating layer. Next, a hollow silica-based fine particle dispersion (P-1) having a solid content concentration of 20 mass% in which the solvent was replaced with ethanol using an ultrafiltration membrane was prepared.

<Preparation of polarizing plate>
(A) Production of Polarizer A long polyvinyl alcohol film having a thickness of 120 μm was uniaxially stretched (temperature: 110 ° C., stretch ratio: 5 times). This was immersed in an aqueous solution composed of 0.075 g of iodine, 5 g of potassium iodide, and 100 g of water for 60 seconds, and then immersed in an aqueous solution at 68 ° C. composed of 6 g of potassium iodide, 7.5 g of boric acid, and 100 g of water. . This was washed with water and dried to obtain a long polarizer.

(B) Production of Polarizing Plate Next, according to the following steps 1 to 5, the polarizer, the cellulose ester films A1 to A26, and the back side cellulose ester films B1 to B20 are bonded together in the combinations shown in Table 4 to produce a polarizing plate. did.

  Step 1: Cellulose ester films A1 to A26 and backside cellulose ester films B1 to B20 were immersed in a 2 mol / L sodium hydroxide solution at 60 ° C. for 90 seconds, then washed with water and dried. A surface of the cellulose ester films A1 to A26 provided with an antireflection layer was previously protected with a peelable protective film (PET).

  Process 2: The above-mentioned polarizer was immersed in a polyvinyl alcohol adhesive tank having a solid content of 2% by mass for 1 to 2 seconds.

  Step 3: Excess adhesive adhered to the polarizer in Step 2 was lightly removed, and it was sandwiched between cellulose ester films A1 to A26 and backside cellulose ester films B1 to B20 subjected to alkali treatment in Step 1 and laminated.

Process 4: It bonded together by the speed of about 2 m / min with the pressure of 20-30 N / cm < ² > with the two rotating rollers. At this time, care was taken to prevent bubbles from entering.

  Step 5: The sample prepared in Step 4 in a dryer at 80 ° C. was dried for 2 minutes to prepare polarizing plates 1 to 49.

  The polarizing plate on the outermost surface of a commercially available liquid crystal display panel (NEC color liquid crystal display MultiSync LCD1525J: model name LA-1529HM) was carefully peeled off, and the polarizing plate having the polarization direction matched thereto was then added to the cellulose ester films A1 to A26. The liquid crystal display devices 1 to 49 shown in Table 4 were prepared by pasting so that the antireflection layer was on the viewing side.

<Evaluation>
The following evaluation was performed using the produced liquid crystal display device.

(Corner unevenness evaluation rank)
A: No corner unevenness (Four-corner front luminance average: 1.00 to 1.05)
○: Corner unevenness cannot be recognized with the naked eye (Four-corner front luminance average: 1.06 to 1.10)
Δ: Appears as corner irregularity, but does not hinder use (average brightness at front of four corners; 1.11 to 1.20)
×: There is a problem in display quality (Four-corner front luminance average; 1.21 or more)
(Viewing angle in an environment of 25 ° C and 90% RH)
(Polar angle range with contrast ratio of 10 or more and no black-side gradation inversion)
◎: Polar angle of 80 ° or more in top, bottom, left, right ○: Top, bottom, left, right Three directions, polar angle of 80 ° or more △: Top, bottom, left, right Two directions, polar angle of 80 ° or more Polar angle over 80 ° in direction

  From the above table, the liquid crystal display devices 1-18, 27-38, 42, 45 using the polarizing plate in which the cellulose esters (A), (B) of the present invention are combined have a humidity of 25 ° C. and 90% RH relative to the comparative example. It can be seen that the lower viewing angle and corner unevenness are excellent.

  Moreover, the level using the cellulose ester film (A) and (B) in the range of the preferable TD elastic modulus of Claim 2 and Claim 3 and MD elastic modulus is 25 degreeC under the humidity of 90% RH. The viewing angle and corner unevenness were more excellent.

It is a correlation diagram of TD elasticity modulus and MD elasticity modulus of a cellulose-ester film (A). It is a correlation diagram of TD elasticity modulus and MD elasticity modulus of a cellulose-ester film (B).

Claims (7)

Cellulose ester film (A) containing an acrylic polymer and satisfying the following formulas (1) and (2) and cellulose ester film (B) containing an acrylic polymer and satisfying the following formula (3) ( A) and (B) A polarizing plate comprising a polarizer sandwiched between two films.
1.4 ≦ (TD elastic modulus / MD elastic modulus) ≦ 2.2 (1)
1.3 ≦ (TD elastic modulus−MD elastic modulus) ≦ 4.0 (2)
0.9 ≦ (TD elastic modulus / MD elastic modulus) ≦ 1.1 (3)
(In the formula, the TD elastic modulus is the elastic modulus in the width direction of the film, and the MD elastic modulus refers to the elastic modulus in the transport direction or longitudinal direction of the film). The TD elastic modulus of the cellulose ester film (A) satisfies the following formula (4), and the TD elastic modulus of the cellulose ester film (B) satisfies the following formula (5). The polarizing plate as described.
4.5 ≦ (TD elastic modulus) ≦ 7.0 (4)
3.0 ≦ (TD elastic modulus) ≦ 5.0 (5)
(In the formula, TD elastic modulus means the elastic modulus in the width direction of the film) The TD elastic modulus and MD elastic modulus of the cellulose ester film (A) are in a region sandwiched between the following formulas (6) and (7). Or the polarizing plate of 2.
(TD elastic modulus−MD elastic modulus) = 2.27 × (TD elastic modulus / MD elastic modulus) −1.18
(6)
(TD elastic modulus−MD elastic modulus) = 1.45 × (TD elastic modulus / MD elastic modulus) −0.75
(7)
(In the formula, the TD elastic modulus is the elastic modulus in the width direction of the film, and the MD elastic modulus refers to the elastic modulus in the transport direction or longitudinal direction of the film). The polarizing plate according to claim 1 or 2, wherein the cellulose ester film (A) is stretched in at least one direction at a stretching ratio of 1.2 times to 1.5 times. The polarizing plate according to claim 1, further comprising a curable resin layer on a surface opposite to a surface to be bonded to the polarizer of the cellulose ester film (A). The polarizing plate according to claim 1, further comprising an antireflection layer on a surface opposite to a surface to be bonded to the polarizer of the cellulose ester film (A). A liquid crystal display device comprising the polarizing plate according to any one of claims 1 to 6 on at least one surface of a liquid crystal cell.

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