JP2014081410A - Cellulose acylate film, polarizing plate and liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thin cellulose acylate film capable of achieving high frontal contrast while preventing display unevenness when assembled in a liquid crystal display device.SOLUTION: The cellulose acylate film comprises cellulose acylate having a total acyl group substitution degree of 2.1 to 2.6 and satisfies the following conditions (1) to (4). (1) The film includes at least one polycondensation ester containing an aromatic dicarboxylic acid residue and an aliphatic diol residue, in which a proportion of the aromatic dicarboxylic acid residue with respect to the whole dicarboxylic acid residues in the polycondensation ester is 70 mol% or more; (2) the film has a thickness of 15 to 45 μm; (3) a retardation (Rth) in a thickness direction at a wavelength of 550 nm satisfies Rth/d≥0.0025, where d represents a film thickness (nm); and (4) an absolute value of a change in Rth in a water contact test is 5 nm or less.

Description

  The present invention relates to a cellulose acylate film, and a polarizing plate and a liquid crystal display device using the cellulose acylate film. In particular, the present invention relates to a cellulose acylate film that can be preferably used as an optical film such as a polarizing plate protective film or a retardation film.

  In recent years, TV applications of liquid crystal display devices have progressed, and there has been an increasing demand for higher image quality and lower price as the screen size increases. In particular, a VA mode liquid crystal display device is the most common liquid crystal display device for TV because it has a relatively high contrast and a relatively high manufacturing yield. A polarizing plate is incorporated in such a liquid crystal display device, and a cellulose acylate film is employed as a protective film for such a polarizing plate (Patent Documents 1 and 2).

On the other hand, in recent years, liquid crystal display devices are increasingly required to be thin. Therefore, it is beneficial if the polarizing plate, which is a component part of the liquid crystal display device, can be thinned.

As a method of reducing the thickness of the polarizing plate, it is conceivable to thin a film (cellulose acylate film) mainly composed of cellulose acylate used as a protective film for the polarizing plate. Here, in order to develop a predetermined retardation (Rth) while reducing the thickness of the cellulose acylate film, a cellulose acylate having a relatively low acyl substitution degree (total acyl substitution degree) is used. It is possible. However, a film using cellulose acylate having a low total acyl substitution degree is likely to cause condensation unevenness. Condensation unevenness is unevenness that occurs when water partially adheres to the surface of a polarizing plate during transportation in the form of cells or modules, and a portion where water adheres and a portion that does not adhere. When such a cellulose acylate film having uneven condensation is incorporated into a liquid crystal display device, there is a concern that display unevenness is caused.
In addition, when a cellulose acylate film is mounted on a thin liquid crystal display device having a panel glass of 500 μm or less and a durability test under high temperature and high humidity is performed, a cell using thin film glass is not suitable. As a result, it has been found that display unevenness of the liquid crystal display device occurs.
Among the display unevenness, the unevenness of the liquid contact part (water contact part unevenness) and the corner unevenness (four corner unevenness) of the liquid crystal display device due to the warp of the cell are serious, and the front contrast of the liquid crystal display device is also affected. give.
Moreover, when only one side of the protective film of the polarizing plate is thinned, the polarizing plate curls, and there is a concern of causing poor bonding at the time of bonding to the cell.

  Furthermore, the use form of the liquid crystal display device is also varied, and durability in various environments such as a low temperature / high humidity environment as well as a high temperature / high humidity environment is required. In the past, the inventor's investigation has revealed that most of the studies have been to improve the durability of polarizing plates in high-temperature and high-humidity environments, which may impair the durability in other environments. It was. Specifically, when the polarizing plate is used for a long period of time in a relatively low temperature and high humidity environment of about 20 ° C., red discoloration may occur. It has been found that this discoloration becomes more pronounced when a polarizing plate having a low moisture permeability polymer film is used.

JP 2011-162769 A JP 2012-108349 A JP 2010-78967 A

  The present invention is intended to solve such problems, and is a polarizing plate having a thin cellulose acylate film, which can be bonded to a cell with a high yield, and is incorporated in a liquid crystal display device. It is an object of the present invention to provide a polarizing plate that is less likely to cause display unevenness and can achieve high front contrast.

Under such circumstances, as a result of intensive studies by the present inventors, it has been found that the above-mentioned problems can be solved by the following means <1>, preferably <2> to <12>.
<1> A cellulose acylate film containing a cellulose acylate having a total acyl group substitution degree of 2.1 to 2.6 and satisfying the following (1) to (4);
(1) It contains at least one polycondensation ester containing an aromatic dicarboxylic acid residue and an aliphatic diol residue, and the ratio of the aromatic dicarboxylic acid residue to all the dicarboxylic acid residues in the polycondensation ester is 70. Mol% or more;
(2) The film thickness is 15 to 45 μm;
(3) Retardation (Rth) in the film thickness direction at a wavelength of 550 nm satisfies Rth / d ≧ 0.0025 (where d indicates film thickness (nm));
(4) The absolute value of Rth change during the water contact test is 5 nm or less;
Here, the absolute value of the Rth change during the water contact test is taken out after the film is immersed in water heated to 40 ° C. for 12 hours, and then water droplets on the surface of the film are wiped off and air-dried, followed by 25 ° C. and 60% relative humidity environment. It is the absolute value of the Rth difference between the Rth at a wavelength of 590 nm and the untreated state after being left for 24 hours.
<2> The cellulose acylate film according to <1>, wherein an internal haze of the cellulose acylate film is 0.05% or less.
<3> The cellulose acylate film according to <1> or <2>, wherein the cellulose acylate is cellulose acetate.
<4> The cellulose acylate film is stretched at a stretching temperature of Tg-70 ° C. to Tg-30 ° C. (Tg is a glass transition temperature of cellulose acylate) in a state where the residual solvent amount is 35 to 65% by mass. The cellulose acylate film according to any one of <1> to <3>.
<5> The cellulose acylate film according to any one of <1> to <4>, wherein the first polarizing plate protective film includes a first polarizing plate protective film and a second polarizing plate protective film. There is a polarizing plate.
<6> The polarizing plate according to <5>, wherein the second polarizing plate protective film has a thickness of 10 to 29 μm.
<7> The polarizing plate according to <5> or <6>, wherein the second polarizing plate protective film has a moisture permeability of 100 g / m ² · 24 hr or less.
<8> A liquid crystal display device comprising the polarizing plate according to any one of <5> to <7>.
<9> The liquid crystal display device according to <8>, wherein the first polarizing plate protective film is disposed on the liquid crystal cell side.
<10> The liquid crystal display device according to <8>, wherein the first polarizing plate protective film is disposed so as to be on a liquid crystal cell side and has a glass with a thickness of 50 to 500 μm.
<11> A cellulose acylate film is stretched at a stretching temperature of Tg-70 ° C. to Tg-30 ° C. (Tg is a glass transition temperature of cellulose acylate) with a residual solvent amount of 35 to 65% by mass. The cellulose acylate film contains a cellulose acylate having a total acyl group substitution degree of 2.1 to 2.6 and satisfies the following (1) and (2): Manufacturing method of
(1) It contains at least one polycondensed ester containing an aromatic dicarboxylic acid residue and an aliphatic diol residue, and the ratio of the aromatic dicarboxylic acid residue to all the dicarboxylic acid residues in the polycondensed ester is 70 mol% or more;
(2) The film thickness is 15 to 45 μm.
<12> The method for producing a cellulose acylate film according to <11>, wherein the cellulose acylate film is the cellulose acylate film according to any one of <1> to <4>.

It is possible to provide a cellulose acylate film which is a thin cellulose acylate film, which is less likely to cause display unevenness when incorporated in a liquid crystal display device and can achieve high front contrast.
Moreover, it is possible to provide a polarizing plate having a thin cellulose acylate film, which has small curling of the polarizing plate, hardly causes display unevenness when incorporated in a liquid crystal display device, and can achieve high front contrast. became.

It is a schematic sectional drawing of an example of the liquid crystal display device of this invention.

  Hereinafter, the contents of the present invention will be described in detail. The description of the constituent elements described below may be made based on typical embodiments of the present invention, but the present invention is not limited to such embodiments. In the present specification, “to” is used to mean that the numerical values described before and after it are included as a lower limit value and an upper limit value. In this specification, “front” means a normal direction relative to the display surface, and “front contrast” means a contrast calculated from white luminance and black luminance measured in the normal direction of the display surface. Shall.

<Cellulose acylate film>
The cellulose acylate film of the present invention contains a cellulose acylate having a total acyl group substitution degree of 2.1 to 2.6 and satisfies the following (1) to (4): (1) aromatic dicarboxylic acid Containing at least one polycondensed ester containing an acid residue and an aliphatic diol residue, the ratio of aromatic dicarboxylic acid residues to all dicarboxylic acid residues in the polycondensed ester being 70 mol% or more;
(2) The film thickness is 15 to 45 μm;
(3) Retardation (Rth) in the film thickness direction at a wavelength of 550 nm satisfies Rth / d ≧ 0.0025 (where d indicates film thickness (nm));
(4) The absolute value of Rth change during the water contact test is 5 nm or less;
Here, the absolute value of the Rth change during the water contact test is taken out after the film is immersed in water heated to 40 ° C. for 12 hours, and then water droplets on the surface of the film are wiped off and air-dried, followed by 25 ° C. and 60% relative humidity environment. It is the absolute value of the Rth difference between the Rth at a wavelength of 590 nm and the untreated state after being left for 24 hours.
Details of these will be described below.

<Cellulose acylate>
The cellulose acylate film used in the present invention contains cellulose acylate having a total acyl substitution degree of 2.1 to 2.6.
Examples of the film material contained in the cellulose acylate film of the present invention include cellulose esters, and ester substitution obtained by introducing a functional group biologically or chemically from the cellulose acylate and other cellulose as raw materials. Examples thereof include compounds having a cellulose skeleton. In addition, it is preferable that the cellulose acylate film of this invention contains the said cellulose acylate as a main component. Here, “as the main component” indicates a polymer when it is composed of a single polymer, and when it is composed of a plurality of polymers, the polymer having the highest mass fraction among the constituent polymers. It shows that.

  The cellulose acylate is an ester of cellulose and carboxylic acid, and the carboxylic acid is more preferably a fatty acid having 2 to 22 carbon atoms, and cellulose acylate being a lower fatty acid having 2 to 4 carbon atoms. Most preferred.

(Cellulose acylate raw material)
Cellulose acylate raw material cellulose used in the present invention includes cotton linter and wood pulp (hardwood pulp, softwood pulp), etc., and any cellulose acylate obtained from any raw material cellulose can be used, optionally mixed. May be. Detailed descriptions of these raw material celluloses can be found in, for example, “Plastic Materials Course (17) Fibrous Resin” (Marusawa, Uda, Nikkan Kogyo Shimbun, published in 1970) and Invention Association Publication Technical Report 2001-1745 ( 7 to 8) can be used, and the cellulose acylate film of the present invention is not particularly limited.

(Degree of substitution of cellulose acylate)
Next, the cellulose acylate suitable for the present invention produced from the above-mentioned cellulose will be described.

  The cellulose acylate used in the present invention is one in which the hydroxyl group of cellulose is acylated, and the substituent can be any acetyl group having 2 carbon atoms to 22 carbon atoms. In the present invention, there is no particular limitation on the measurement of the degree of substitution of cellulose with a hydroxyl group in cellulose acylate, but the degree of binding of acetic acid and / or a fatty acid having 3 to 22 carbon atoms substituted with a hydroxyl group of cellulose is measured and calculated. The degree of substitution can be obtained. As a measuring method, it can carry out according to ASTM D-817-91.

In the cellulose acylate used in the present invention, the cellulose acylate preferably has a total acyl substitution degree of 2.1 to 2.6, and the total acyl substitution degree is preferably 2.3 to 2.6.
If the total acyl substitution degree of the cellulose acylate used in the present invention is in the above preferred range, it is more preferable in terms of optical properties and humidity stability of the optical properties, and if it is 2.6 or less, the viewpoint of lowering haze can be achieved. To preferred.

  Among the acetic acid substituted for the hydroxyl group of cellulose and / or the fatty acid having 3 to 22 carbon atoms, the acyl group having 2 to 22 carbon atoms may be an aliphatic group or an aryl group, and is not particularly limited. A mixture of They are, for example, alkyl carbonyl esters, alkenyl carbonyl esters, aromatic carbonyl esters, or aromatic alkyl carbonyl esters of cellulose, each of which may further have a substituted group. These preferred acyl groups include acetyl, propionyl, butanoyl, heptanoyl, hexanoyl, octanoyl, decanoyl, dodecanoyl, tridecanoyl, tetradecanoyl, hexadecanoyl, octadecanoyl I-butanoyl group, t-butanoyl group, cyclohexanecarbonyl group, oleoyl group, benzoyl group, naphthylcarbonyl group, cinnamoyl group and the like. Among these, acetyl group, propionyl group, butanoyl group, dodecanoyl group, octadecanoyl group, t-butanoyl group, oleoyl group, benzoyl group, naphthylcarbonyl group, cinnamoyl group and the like are preferable, and acetyl group, propionyl group, butanoyl group are preferable. Groups are more preferred. Further preferred groups are an acetyl group and propionyl, and the most preferred group is an acetyl group (when the cellulose acylate is cellulose acetate).

  The degree of polymerization of the cellulose acylate preferably used in the present invention is preferably 180 to 700 in terms of viscosity average degree of polymerization. In cellulose acetate, 180 to 550 is more preferable, 180 to 400 is more preferable, and 180 to 350. Is particularly preferred. If the degree of polymerization is not more than the upper limit, the viscosity of the cellulose acylate dope solution does not become too high, and a film can be easily produced by casting. If the degree of polymerization is equal to or greater than the lower limit, it is preferable because there is no inconvenience such as a decrease in strength of the produced film. The viscosity average degree of polymerization can be measured by Uda et al.'S intrinsic viscosity method {Kazuo Uda, Hideo Saito, "Journal of the Textile Society," Vol. 18, No. 1, pages 105-120 (1962)}. This method is also described in detail in JP-A-9-95538.

  The molecular weight distribution of cellulose acylate preferably used in the present invention is evaluated by gel permeation chromatography, and its polydispersity index Mw / Mn (Mw is a mass average molecular weight, Mn is a number average molecular weight) is small, and the molecular weight A narrow distribution is preferred. The specific value of Mw / Mn is preferably 1.0 to 4.0, more preferably 2.0 to 4.0, and most preferably 2.3 to 3.4. preferable.

<Polycondensation SL>
In the present invention, at least one polycondensation ester containing an aromatic dicarboxylic acid residue and an aliphatic diol residue is contained, and the ratio of the aromatic dicarboxylic acid residue to all the dicarboxylic acid residues in the polycondensation ester is 70. More than mol%. When such a polycondensed ester is blended, the expression of retardation is enhanced, and the membrane can be effectively hydrophobized. In addition, in the polycondensed ester having many aromatic units, an interaction between the aromatic ring and the cellulose acylate occurs, and the orientation of the polycondensed ester is difficult to change even in the state of containing water. It is thought that there is an effect | action which a foundation change reduces.

In the polycondensation ester used in the present invention, both ends are independently —OH group, —O—C (═O) —R ¹ group, —C (═O) —O—R ² group, —O—. It is preferably any one selected from the group consisting of an R ³ group and a —COOH group (provided that R ^{1 to} R ³ each independently represents an aliphatic group).

  In the present specification, the residue of the polycondensed ester is a partial structure of the polycondensed ester and represents a partial structure having the characteristics of the monomer forming the polycondensed ester. For example, the dicarboxylic acid residue formed from the dicarboxylic acid HOOC-R—COOH is —OC—R—CO—, and the diol residue formed from the diol HO—R′—OH is —O—R′—O—. It is.

In the polycondensed ester, an aromatic dicarboxylic acid residue is used as the dicarboxylic acid residue.
In addition, the ratio of aromatic dicarboxylic acid residues to all dicarboxylic acid residues in the polycondensation ester used in the present invention is 70 mol% or more, preferably 80% or more, and preferably 90% or more. More preferred.
By setting the aromatic dicarboxylic acid residue ratio to 70 mol% or more, a cellulose acylate film can be obtained that exhibits sufficient optical expression even when the film thickness is thin (particularly, the value of Rth per film thickness is large). There is a tendency.

In the present specification, the aromatic dicarboxylic acid residue refers to a dicarboxylic acid residue containing at least one arylene group. That is, in the present specification, the aromatic dicarboxylic acid residue includes, for example, -OC-Ar'-L-CO- and -OC-L'- in addition to -OC-Ar-CO- residue. Dicarboxylic acid residues having a structure such as Ar ″ —CO— or —OC—L ″ —Ar ′ ″ — L ″ —CO— (Ar, Ar ′, Ar ″ and Ar ′ ″ described above) Each independently represents an arylene group, and L, L ′ and L ″ each independently represents a divalent linking group other than an arylene group). Examples of the divalent linking group other than the arylene group include an aliphatic group and an atom linking group, and specific examples include an alkylene group, an alkyleneoxy group, an oxygen atom, and a sulfur atom. it can.
Among these, the aromatic dicarboxylic acid residue preferably has a structure of —OC—Ar—CO— residue from the viewpoint of compatibility with cellulose acylate.

  Ar is preferably an arylene group having 6 to 16 carbon atoms, more preferably an arylene group having 6 to 12 carbon atoms, particularly preferably a phenylene group or a naphthylene group, and a phenylene group. Is more particularly preferred. The Ar may or may not further have a substituent, but preferably does not have a substituent. Examples of the substituent include a hydroxyl group, an acyl group, and a carbonyl group. Examples include groups.

Specific examples of the aromatic dicarboxylic acid residue include phthalic acid residue, terephthalic acid residue, isophthalic acid residue, 1,5-naphthalenedicarboxylic acid residue, 1,4-naphthalenedicarboxylic acid residue, 1, Examples thereof include an 8-naphthalenedicarboxylic acid residue, a 2,8-naphthalenedicarboxylic acid residue, and a 2,6-naphthalenedicarboxylic acid residue. Among these examples, phthalic acid residues, terephthalic acid residues, and 2,6-naphthalenedicarboxylic acid residues are preferable, phthalic acid residues and terephthalic acid residues are more preferable, and terephthalic acid residues are more preferable.
In the polycondensed ester, an aromatic dicarboxylic acid residue is formed by the aromatic dicarboxylic acid used for mixing.
When the polycondensed ester contains a terephthalic acid residue as an aromatic dicarboxylic acid residue, it is more compatible with cellulose acylate and causes bleed-out during film formation and heat stretching of the cellulose acylate film. It can be set as a difficult cellulose acylate film.

  Further, the polycondensed ester may contain only one kind of aromatic dicarboxylic acid residue or two or more kinds thereof. When two types of aromatic dicarboxylic acid residues are included in the polycondensed ester, it is preferable that a phthalic acid residue and a terephthalic acid residue are included.

The polycondensed ester has an aliphatic dicarboxylic acid residue in addition to the aromatic dicarboxylic acid residue as long as the ratio of the aromatic dicarboxylic acid residue is 70 mol% or more with respect to all the dicarboxylic acid residues in the polycondensed ester. An acid residue may be included.
Specific examples of the aliphatic dicarboxylic acid residue include, for example, oxalic acid residue, malonic acid residue, succinic acid residue, maleic acid residue, fumaric acid residue, glutaric acid residue, adipic acid residue, Examples thereof include a pimelic acid residue, a suberic acid residue, an azelaic acid residue, a sebacic acid residue, a dodecanedicarboxylic acid residue, or a 1,4-cyclohexanedicarboxylic acid residue.
In the polycondensed ester, an aliphatic dicarboxylic acid residue is formed from the aliphatic dicarboxylic acid used for mixing.
The aliphatic dicarboxylic acid residue preferably has an average carbon number of 5.5 to 10.0, more preferably 5.5 to 8.0, and 5.5 to 7.0. Is more preferable. If the average carbon number of the aliphatic diol is 7.0 or less, the heat loss of the compound can be reduced, and the occurrence of planar failure that may be caused by process contamination due to bleed-out when the cellulose acylate web is dried can be prevented. . Moreover, it is preferable that the aliphatic diol has an average carbon number of 2.5 or more because the compatibility is excellent and precipitation of the polycondensed ester hardly occurs.
Specifically, when the polymerizable ester includes the aliphatic dicarboxylic acid residue, the polymerizable ester preferably includes a succinic acid residue or an adipic acid residue, and more preferably includes a succinic acid residue.
The polycondensed ester may contain only one type of aliphatic dicarboxylic acid residue or two or more types. When two types of aliphatic dicarboxylic acid residues are contained in the polycondensed ester, it is preferable that a succinic acid residue and an adipic acid residue are contained. When one kind of aliphatic dicarboxylic acid residue is contained in the polycondensed ester, it is preferable that a succinic acid residue is contained. By setting it as such an aspect, the average carbon number of a diol residue can be adjusted to the said preferable range, and compatibility with a cellulose acylate becomes favorable.

  In the polycondensed ester, an aliphatic diol residue is used as a diol residue.

  Examples of the aliphatic diol used in the present invention include alkyl diols and alicyclic diols, such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl-1,3-propanediol (neopentyl glycol), 2,2-diethyl-1,3-propanediol (3,3-dimethylolpentane), 2-n-butyl-2-ethyl-1,3-propanediol (3,3-dimethylolheptane), 3- Methyl-1,5-pentanediol, 1,6-hexanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl -1,3-hexanediol, 2-methyl-1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-octadecanediol, diethylene glycol, cyclohexanedimethanol, etc. Is preferably used together with ethylene glycol as one or a mixture of two or more.

Among them, in the present invention, the ratio of the aliphatic diol residue having 3 or more carbon atoms to all diol residues (hereinafter also referred to as the ratio of aliphatic diol having 3 or more carbon atoms) is 30 mol. % Or more of the polycondensation ester is preferable from the viewpoint of improving the compatibility between the cellulose acylate and the polycondensation ester and improving the solubility of the polycondensation ester in the solvent.
The ratio of the aliphatic diol having 3 or more carbon atoms is more preferably 30 mol% or more, and particularly preferably 50 to 80 mol%.

Examples of the aliphatic diol residue having 3 or more carbon atoms include 1,2-propanediol residue, 1,3-propanediol residue, 1,2-butanediol residue, 1,3-butanediol residue, 2-methyl-1,3-propanediol residue, 1,4-butanediol residue, 1,5-pentanediol residue, 2,2-dimethyl-1,3-propanediol (neopentyl glycol) residue, Examples include 1,4-hexanediol residue, 1,4-cyclohexanediol residue and the like. Among them, the aliphatic diol residue having 3 or more carbon atoms preferably used in the present invention includes 1,2-propanediol residue, 1,3-propanediol residue, 1,2-butanediol residue, 1, 3-butanediol residue, 2-methyl-1,3-propanediol residue, 1,4-butanediol residue, 1,5-pentanediol residue, 2,2-dimethyl-1,3-propanediol ( Neopentyl glycol) residue, more preferably 1,2-propanediol residue, 1,3-propanediol residue residue, 1,2-butanediol, 1,3-butanediol residue. Group, 2-methyl-1,3-propanediol residue, 1,4-butanediol residue, particularly preferably 1,2-propanediol residue.
By using a 1,2-propanediol residue or a 1,3-propanediol residue, crystallization of the polycondensed ester can be prevented.

When an aliphatic diol residue is used as a diol residue other than the aliphatic diol having 3 or more carbon atoms, an ethylene glycol residue or the like can be used.
In the polycondensed ester, an aliphatic diol residue is formed by the aliphatic diol used for mixing.

  The polycondensed ester may contain only one type of aliphatic diol residue or two or more types. When two types of aliphatic diol residues are included in the polycondensed ester, it is preferable that 1,2-propanediol residues and ethylene glycol residues are included.

The polycondensed ester may contain an aromatic diol residue in addition to the aliphatic diol residue.
Specific examples of the aromatic diol residue include, for example, bisphenol A residue, 1,2-hydroxybenzene residue, 1,3-hydroxybenzene residue, 1,4-hydroxybenzene residue, 1,4- Examples thereof include benzenedimethanol residues.

In the present invention, it is particularly preferable that the terminal is capped with an alkyl group or an aromatic group and is a polycondensed ester. This is because the terminal is protected with a hydrophobic functional group, which is effective against deterioration with time at high temperature and high humidity, and is due to the role of delaying hydrolysis of the ester group.
It is preferable to protect the polycondensed ester of the present invention with a monoalcohol residue or a monocarboxylic acid residue so that both ends of the polycondensed ester are not carboxylic acid or OH group.
In this case, the monoalcohol is preferably a substituted or unsubstituted monoalcohol having 1 to 30 carbon atoms, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, pentanol, isopentanol, hexanol, isohexanol, cyclohexyl alcohol. , Octanol, isooctanol, 2-ethylhexyl alcohol, nonyl alcohol, isononyl alcohol, tert-nonyl alcohol, decanol, dodecanol, dodecahexanol, aliphatic alcohol such as dodecaoctanol, allyl alcohol, oleyl alcohol, benzyl alcohol, 3-phenyl Examples thereof include substituted alcohols such as propanol.

  End-capping alcohols that can be preferably used are methanol, ethanol, propanol, isopropanol, butanol, isobutanol, isopentanol, hexanol, isohexanol, cyclohexyl alcohol, isooctanol, 2-ethylhexyl alcohol, isononyl alcohol, oleyl alcohol Benzyl alcohol, in particular methanol, ethanol, propanol, isobutanol, cyclohexyl alcohol, 2-ethylhexyl alcohol, isononyl alcohol, benzyl alcohol.

  Moreover, when sealing with a monocarboxylic acid residue, the monocarboxylic acid used as a monocarboxylic acid residue is preferably a substituted or unsubstituted monocarboxylic acid having 1 to 30 carbon atoms. These may be aliphatic monocarboxylic acids or aromatic ring-containing carboxylic acids. Preferred aliphatic monocarboxylic acids are described, for example, acetic acid, propionic acid, butanoic acid, caprylic acid, caproic acid, decanoic acid, dodecanoic acid, stearic acid, oleic acid, and examples of the aromatic ring-containing monocarboxylic acid include Benzoic acid, p-tert-butylbenzoic acid, p-tert-amylbenzoic acid, orthotoluic acid, metatoluic acid, p-toluic acid, dimethylbenzoic acid, ethylbenzoic acid, normal propylbenzoic acid, aminobenzoic acid, acetoxybenzoic acid, etc. Yes, these can be used alone or in combination of two or more.

  Although the specific example of the said polycondensation ester is described in the following Table 1, this invention is not limited to the following specific examples.

(Method for synthesizing polycondensed ester)
The polycondensation ester used in the present invention can be synthesized by a conventional method such as a hot melt condensation method using a polyesterification reaction or transesterification reaction between a diol and a dicarboxylic acid, or an interfacial condensation method between an acid chloride of these acids and a glycol. It can be easily synthesized by either method. In addition, the polycondensed ester according to the present invention is described in detail in Koichi Murai, “Plasticizer Theory and Application” (Kokai Shobo Co., Ltd., first edition issued on March 1, 1973). In addition, Japanese Patent Laid-Open Nos. 05-155809, 05-155810, Japanese Patent Laid-Open Nos. 05-97073, 2006-259494, 07-330670, 2006-342227, 2007-003679. The materials described in each publication can also be used.

<Other ingredients>
In addition to the polycondensed ester, a sugar ester, a retardation enhancer, a low molecular weight additive and the like can be appropriately used for the cellulose acylate film of the present invention as necessary.

(Sugar ester)
The sugar ester compound refers to a compound in which at least one substitutable group (for example, a hydroxyl group or a carboxyl group) in the polysaccharide constituting the compound and at least one substituent are ester-bonded. . That is, the sugar ester compound referred to here includes a wide range of sugar derivatives, for example, a compound containing a sugar residue such as gluconic acid as a structure. That is, the sugar ester compound includes an ester of glucose and carboxylic acid and an ester of gluconic acid and alcohol.
The substitutable group in the polysaccharide constituting the sugar ester compound is preferably a hydroxyl group.

  The sugar ester compound includes a structure derived from a polysaccharide constituting the sugar ester compound (hereinafter also referred to as a sugar residue). The structure of the sugar residue per monosaccharide is referred to as the structural unit of the sugar ester compound. The structural unit of the sugar ester compound preferably includes a pyranose structural unit or a furanose structural unit, and more preferably all sugar residues are a pyranose structural unit or a furanose structural unit. Further, when the sugar ester is composed of a polysaccharide, it preferably contains both a pyranose structural unit or a furanose structural unit.

  The sugar residue of the sugar ester compound may be derived from 5 monosaccharides or 6 monosaccharides, but is preferably derived from 6 monosaccharides.

  The number of structural units contained in the sugar ester compound is preferably 2 to 4, more preferably 2 to 3, and particularly preferably 2. That is, the sugar constituting the sugar ester compound is preferably a disaccharide to a tetrasaccharide, more preferably a disaccharide to a trisaccharide, and particularly preferably a disaccharide.

  In the present invention, the sugar ester compound is more preferably a sugar ester compound containing 2 to 4 pyranose structural units or furanose structural units in which at least one hydroxyl group is esterified, and at least one of the hydroxyl groups is esterified. More preferably, the sugar ester compound contains two pyranose structural units or furanose structural units.

  Examples of the monosaccharides or saccharides containing 2 to 4 monosaccharide units include, for example, erythrose, threose, ribose, arabinose, xylose, lyxose, allose, altrose, glucose, fructose, mannose, gulose, idose, galactose , Talose, trehalose, isotrehalose, neotrehalose, trehalosamine, caudibiose, nigerose, maltose, maltitol, isomaltose, sophorose, laminaribiose, cellobiose, gentiobiose, lactose, lactosamine, lactitol, lactulose, melibiose, primebelloose, rutiose , Sucrose, sucralose, turanose, vicyanose, cellotriose, cacotriose, gentianose, isomaltori , Isopanose, maltotriose, manninotriose, melenotriose, panose, planteose, raffinose, solatriose, umbelliferose, lycotetraose, maltotetraose, stachyose, baltopentaose, velval course, maltohexaose , Xylitol, sorbitol and the like.

  Preferably, ribose, arabinose, xylose, lyxose, glucose, fructose, mannose, galactose, trehalose, maltose, cellobiose, lactose, sucrose, sucralose, xylitol, sorbitol, more preferably arabinose, xylose, glucose, fructose, mannose , Galactose, maltose, cellobiose and sucrose, particularly preferably xylose, glucose, fructose, mannose, galactose, maltose, cellobiose, sucrose, xylitol and sorbitol.

  Preferred examples of the substituent of the sugar ester compound include an alkyl group (preferably an alkyl group having 1 to 22 carbon atoms, more preferably 1 to 12 carbon atoms, and particularly preferably an alkyl group having 1 to 8 carbon atoms, such as a methyl group, An ethyl group, a propyl group, a hydroxyethyl group, a hydroxypropyl group, a 2-cyanoethyl group, a benzyl group, etc.), an aryl group (preferably having a carbon number of 6 to 24, more preferably 6 to 18 and particularly preferably 6 to 12). A group such as a phenyl group or a naphthyl group, an acyl group (preferably having a carbon number of 1 to 22, more preferably a carbon number of 2 to 12, particularly preferably a carbon number of 2 to 8, such as an acetyl group or a propionyl group, Butyryl group, pentanoyl group, hexanoyl group, octanoyl group, benzoyl group, toluyl group, phthalyl group), amide group (preferred) Or an amide group (preferably 4 to 22 carbon atoms, more preferably an amide having 2 to 12 carbon atoms, particularly preferably an amide having 2 to 8 carbon atoms, such as a formamide group or an acetamide group). May include amide groups having 4 to 12 carbon atoms, particularly preferably 4 to 8 carbon atoms (for example, succinimide group, phthalimide group, etc.). Among them, an alkyl group or an acyl group is more preferable, a methyl group, an acetyl group, a propionyl group, a butyryl group (among them, i-butyryl group is preferable), a benzoyl group is more preferable, and at least one of the acetyl group and the butyryl group is selected. It is particularly preferable to include the acetyl group, and it is particularly preferable to include only the acetyl group or both the acetyl group and the butyryl group.

  Examples of the sugar ester compound used in the present invention include the following compounds. However, the sugar ester compounds that can be used in the present invention are not limited to these. In the following structural formulas, R each independently represents an arbitrary substituent, and a plurality of R may be the same or different.

  Other examples of the sugar ester compound include JP 2001-247717 A, JP 2005-515285 A, International Publication WO 2007/125765, International Publication WO 2009/011228, International Publication WO 2009/031464, and the like. The sugar ester compounds described can also be used.

  As the method for obtaining the sugar ester compound, commercially available products such as those manufactured by Tokyo Chemical Industry Co., Ltd., Aldrich, etc., or known ester derivatization methods for commercially available carbohydrates (for example, Japanese Patent Laid-Open No. Hei. Can be synthesized by carrying out the method described in JP-A-8-245678.

  The sugar ester compound has a number average molecular weight of preferably 200 to 3500, more preferably 420 to 3000, and particularly preferably 450 to 2000.

  The sugar ester compound is preferably contained in an amount of 2 to 35% by mass, more preferably 5 to 20% by mass, and particularly preferably 10 to 15% by mass with respect to the cellulose acylate.

(Retardation expression agent)
The film of the present invention may contain a retardation enhancer in order to develop a retardation value. The retardation developer is not particularly limited, and examples thereof include a rod-shaped retardation developer (hereinafter also referred to as a rod-shaped compound) or a disk-shaped retardation developer (hereinafter also referred to as a disk-shaped compound). Discotic compounds are preferred. Such a discotic compound makes it easy to develop retardation, and also has a function of hydrophobizing the membrane, so that a change in retardation before and after water treatment can be reduced.
The addition amount of the retardation developer composed of the rod-shaped compound is preferably 0.1 parts by mass or more and less than 3 parts by mass, and 0.5 parts by mass or more and less than 2 parts by mass with respect to 100 parts by mass of the cellulose acylate component. More preferably it is. On the other hand, the discotic compound is preferably 0.1 to 10% by mass, more preferably 0.5 to 4% by mass, and 1 to 3% by mass with respect to the cellulose acylate. Is particularly preferred.
Since the discotic compound is superior to the rod-shaped compound in Rth retardation expression, it is preferably used when a particularly large Rth retardation is required. Two or more retardation developers may be used in combination.
The retardation developer preferably has a maximum absorption in the wavelength region of 250 to 400 nm, and preferably has substantially no absorption in the visible region.

The discotic compound will be described. As the discotic compound, a compound having at least two aromatic rings can be used.
In the present specification, the “aromatic ring” includes an aromatic hetero ring in addition to an aromatic hydrocarbon ring.
The aromatic hydrocarbon ring is particularly preferably a 6-membered ring (that is, a benzene ring).
The aromatic heterocycle is generally an unsaturated heterocycle. The aromatic heterocycle is preferably a 5-membered ring, 6-membered ring or 7-membered ring, more preferably a 5-membered ring or 6-membered ring. Aromatic heterocycles generally have the most double bonds. As the hetero atom, a nitrogen atom, an oxygen atom and a sulfur atom are preferable, and a nitrogen atom is particularly preferable. Examples of aromatic heterocycles include furan ring, thiophene ring, pyrrole ring, oxazole ring, isoxazole ring, thiazole ring, isothiazole ring, imidazole ring, pyrazole ring, furazane ring, triazole ring, pyran ring, pyridine ring , Pyridazine ring, pyrimidine ring, pyrazine ring and 1,3,5-triazine ring.
As the aromatic ring, a benzene ring, a condensed benzene ring, and biphenyls are preferable. In particular, a 1,3,5-triazine ring is preferably used. Specifically, for example, compounds disclosed in JP-A No. 2001-166144 are preferably used.

The number of carbon atoms of the aromatic ring in the retardation enhancer is preferably 2-20, more preferably 2-12, still more preferably 2-8, and 2-6. Most preferred.
The bonding relationship between two aromatic rings can be classified into (a) when a condensed ring is formed, (b) when directly linked by a single bond, and (c) when linked via a linking group (for aromatic rings). , Spiro bonds cannot be formed). The connection relationship may be any of (a) to (c).

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

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

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

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

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

The number of carbon atoms in the aliphatic acyl group is preferably 1-10. Examples of the aliphatic acyl group include an acetyl group, a propanoyl group, and a butanoyl group.
The number of carbon atoms in the aliphatic acyloxy group is preferably 1-10. Examples of the aliphatic acyloxy group include an acetoxy group.
The number of carbon atoms of the alkoxy group is preferably 1-8. The alkoxy group may further have a substituent (for example, an alkoxy group). Examples of the alkoxy group (including a substituted alkoxy group) include a methoxy group, an ethoxy group, a butoxy group, and a methoxyethoxy group.
The number of carbon atoms of the alkoxycarbonyl group is preferably 2-10. Examples of the alkoxycarbonyl group include a methoxycarbonyl group and an ethoxycarbonyl group.
The number of carbon atoms of the alkoxycarbonylamino group is preferably 2-10. Examples of the alkoxycarbonylamino group include a methoxycarbonylamino group and an ethoxycarbonylamino group.

The alkylthio group preferably has 1 to 12 carbon atoms. Examples of the alkylthio group include a methylthio group, an ethylthio group, and an octylthio group.
The alkylsulfonyl group preferably has 1 to 8 carbon atoms. Examples of the alkylsulfonyl group include a methanesulfonyl group and an ethanesulfonyl group.
The number of carbon atoms in the aliphatic amide group is preferably 1-10. Examples of the aliphatic amide group include acetamide.
The number of carbon atoms of the aliphatic sulfonamide group is preferably 1-8. Examples of the aliphatic sulfonamido group include a methanesulfonamido group, a butanesulfonamido group, and an n-octanesulfonamido group.
The number of carbon atoms of the aliphatic substituted amino group is preferably 1-10. Examples of the aliphatic substituted amino group include a dimethylamino group, a diethylamino group, and a 2-carboxyethylamino group.
The number of carbon atoms in the aliphatic substituted carbamoyl group is preferably 2-10. Examples of the aliphatic substituted carbamoyl group include a methylcarbamoyl group and a diethylcarbamoyl group.
The number of carbon atoms in the aliphatic substituted sulfamoyl group is preferably 1-8. Examples of the aliphatic substituted sulfamoyl group include a methylsulfamoyl group and a diethylsulfamoyl group.
The number of carbon atoms in the aliphatic substituted ureido group is preferably 2-10. Examples of the aliphatic substituted ureido group include a methylureido group.
Examples of the non-aromatic heterocyclic group include a piperidino group and a morpholino group.
The molecular weight of the retardation developer is preferably 300 to 800.

  In the present invention, it is preferable to use a triazine compound represented by the following general formula (I) as the discotic compound.

In the above general formula (I):
R ²⁰¹ each independently represents an aromatic ring or a heterocyclic ring having a substituent in at least one of the ortho, meta and para positions.
X ²⁰¹ each independently represents a single bond or —NR ²⁰² —. Here, each R ²⁰² independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, an alkenyl group, an aryl group, or a heterocyclic group.

The aromatic ring represented by R ²⁰¹ is preferably phenyl or naphthyl, particularly preferably phenyl. The aromatic ring R ²⁰¹ represents may have at least one substituent at any substitutable position. Examples of the substituent include halogen atom, hydroxyl group, cyano group, nitro group, carboxyl group, alkyl group, alkenyl group, aryl group, alkoxy group, alkenyloxy group, aryloxy group, acyloxy group, alkoxycarbonyl group, Alkenyloxycarbonyl group, aryloxycarbonyl group, sulfamoyl group, alkyl-substituted sulfamoyl group, alkenyl-substituted sulfamoyl group, aryl-substituted sulfamoyl group, sulfonamide group, carbamoyl, alkyl-substituted carbamoyl group, alkenyl-substituted carbamoyl group, aryl-substituted carbamoyl group, amide Groups, alkylthio groups, alkenylthio groups, arylthio groups and acyl groups.

The heterocyclic group represented by ^R201 preferably has aromaticity. The heterocycle having aromaticity is generally an unsaturated heterocycle, preferably a heterocycle having the largest number of double bonds. The heterocyclic ring is preferably a 5-membered ring, 6-membered ring or 7-membered ring, more preferably a 5-membered ring or 6-membered ring, and most preferably a 6-membered ring. The hetero atom of the heterocyclic ring is preferably a nitrogen atom, a sulfur atom or an oxygen atom, and particularly preferably a nitrogen atom. As the heterocyclic ring having aromaticity, a pyridine ring (2-pyridyl or 4-pyridyl as the heterocyclic group) is particularly preferable. The heterocyclic group may have a substituent. Examples of the substituent of the heterocyclic group are the same as the examples of the substituent of the aryl moiety.
When X ²⁰¹ is a single bond, the heterocyclic group is preferably a heterocyclic group having a free valence on the nitrogen atom. The heterocyclic group having a free valence on the nitrogen atom is preferably a 5-membered ring, 6-membered ring or 7-membered ring, more preferably a 5-membered ring or 6-membered ring, and a 5-membered ring. Is most preferred. The heterocyclic group may have a plurality of nitrogen atoms. Further, the heterocyclic group may have a hetero atom other than the nitrogen atom (for example, O, S). Examples of heterocyclic groups having free valences on nitrogen atoms are shown below. Here, -C ₄ H ₉ ⁿ represents a n-C ₄ H _9.

The alkyl group represented by R ²⁰² may be a cyclic alkyl group or a chain alkyl group, but a chain alkyl group is preferable, and a linear alkyl group is more preferable than a branched chain alkyl group. preferable. The number of carbon atoms in the alkyl group is preferably 1-30, more preferably 1-20, further preferably 1-10, still more preferably 1-8, and 1-6. Most preferred. The alkyl group may have a substituent. Examples of the substituent include a halogen atom, an alkoxy group (for example, methoxy group, ethoxy group) and an acyloxy group (for example, acryloyloxy group, methacryloyloxy group).

The alkenyl group represented by R ²⁰² may be a cyclic alkenyl group or a chain alkenyl group, but is preferably a chain alkenyl group and is more preferably a linear alkenyl group than a branched chain alkenyl group. More preferably it represents a group. The number of carbon atoms in the alkenyl group is preferably 2 to 30, more preferably 2 to 20, still more preferably 2 to 10, still more preferably 2 to 8, 6 is most preferred. The alkenyl group may have a substituent. Examples of the substituent are the same as those of the alkyl group described above.
The aromatic ring group and heterocyclic group represented by R ²⁰² are the same as the aromatic ring and heterocyclic ring represented by R ²⁰¹ , and the preferred range is also the same. The aromatic ring group and the heterocyclic group may further have a substituent, and examples of the substituent are the same as those of the aromatic ring and heterocyclic ring of ^R201 .

  The compound represented by the general formula (I) can be synthesized by a known method such as the method described in JP-A-2003-344655. Details of the retardation enhancer are described on page 49 of published technical bulletin 2001-1745.

（一般式（ＩＩ−１）中、Ｙ¹はメチン基、あるいは−Ｎ−を表す。Ｒａ³¹はアルキル基、アルケニル基、アルキニル基、アリール基または複素環基を表す。Ｒｂ³¹、Ｒｃ³¹、Ｒｄ³¹およびＲｅ³¹はそれぞれ独立に水素原子、アルキル基、アルケニル基、アルキニル基、アリール基または複素環基を表す。Ｑ²¹は単結合、−Ｏ−、−Ｓ−、あるいは−ＮＲｆ−を示し、Ｒｆは水素原子、アルキル基、アルケニル基、アルキニル基、アリール基、または複素環基を表し、Ｒａ³¹と連結して環を形成してもよい。Ｘ³¹、Ｘ³²、およびＸ³³は、それぞれ独立に単結合または２価の連結基を表す。Ｘ³⁴は、下記一般式（Ｑ）
一般式（Ｑ） Moreover, you may contain the compound represented by following formula (II-1) other than the said compound.

(In General Formula (II-1), Y ¹ represents a methine group or —N—. Ra ³¹ represents an alkyl group, an alkenyl group, an alkynyl group, an aryl group, or a heterocyclic group. Rb ³¹ , Rc ³¹ , Rd ³¹ and Re ³¹ each independently represents a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group or a heterocyclic group, and Q ²¹ represents a single bond, —O—, —S— or —NRf—. , Rf represents a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, or a heterocyclic group, and may be linked to Ra ³¹ to form a ring, X ³¹ , X ³² , and X ³³ are Each independently represents a single bond or a divalent linking group, X ³⁴ represents the following general formula (Q);
General formula (Q)

（一般式（Ｑ）中、＊側が前記一般式（ＩＩ−１）で表される化合物中の複素環に置換しているＮ原子との連結部位である。）
で表される２価の連結基からなる群から選択される連結基を表す。）

(In general formula (Q), the * side is the linking site with the N atom substituted on the heterocyclic ring in the compound represented by general formula (II-1).)
A linking group selected from the group consisting of divalent linking groups represented by )

  Specific examples of the optical developing agent are given below, but the present invention is not limited to the following specific examples.

(Low molecular weight additive)
Examples of the low molecular weight additive include an Rth control agent / adjusting agent, a deterioration preventing agent, an ultraviolet ray preventing agent, other plasticizers, and an infrared absorber. These may be solid or oily. That is, the melting point and boiling point are not particularly limited. For example, mixing of an ultraviolet absorbing material at 20 ° C. or lower and 20 ° C. or higher, and a mixture of deterioration preventing agents are also possible. Furthermore, infrared absorbing dyes are described, for example, in JP-A No. 2001-194522. Moreover, the addition time may be added at any time in the cellulose acylate solution (dope) preparation step, but may be added by adding a step of adding an additive to the final preparation step of the dope preparation step. Furthermore, the amount of each material added is not particularly limited as long as the function is manifested.

  In the polymer solution, a deterioration preventing agent (for example, an antioxidant, a peroxide decomposing agent, a radical inhibitor, a metal deactivator, an acid scavenger, an amine) may be added. The deterioration inhibitors are described in JP-A-3-199201, JP-A-597073, JP-A-5-194789, JP-A-5-271471, and JP-A-6-107854. The amount of the deterioration inhibitor added is 0.01 of the solution (dope) to be prepared from the viewpoint that the effect of the addition of the deterioration inhibitor is manifested and that the deterioration inhibitor is prevented from bleeding out on the film surface. It is preferably ˜1% by mass, more preferably 0.01-0.2% by mass. Particularly preferable examples of the deterioration inhibitor include butylated hydroxytoluene (BHT) and tribenzylamine (TBA).

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

(Matting agent fine particles)
The polymer solution preferably contains fine particles as a matting agent. Examples of fine particles that can be used in the present invention include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate and calcium phosphate. Can do. Fine particles containing silicon are preferable in terms of low turbidity, and silicon dioxide is particularly preferable. The fine particles of silicon dioxide preferably have a primary average particle size of 20 nm or less and an apparent specific gravity of 70 g / L or more. Those having an average primary particle size as small as 5 to 16 nm are more preferred because they can reduce the haze of the film. The apparent specific gravity is preferably 90 to 200 g / L, more preferably 100 to 200 g / L. A larger apparent specific gravity is preferable because a high-concentration dispersion can be produced, and haze and aggregates are improved. A desirable embodiment is described in detail in pages 35 to 36 of the Japan Society for Invention and Technology (Publication No. 2001-1745, published on March 15, 2001, Japan Society of Invention), and the cellulose acylate film of the present invention. It can also be preferably used in the production method.

  In addition to the above, other additives may be added to the cellulose acylate film of the present invention within a range not departing from the gist of the present invention. Specifically, a peeling accelerator, a deterioration preventing agent and the like are exemplified.

<Characteristics of cellulose acylate film>
(Layer structure of cellulose acylate film)
The film of the present invention may be a single layer film or may have a laminated structure of two or more layers, but is preferably a single layer film.

(Film thickness)
The film of the present invention has a thickness of 15 to 45 μm. By using such a thin cellulose acylate film, a thin polarizing plate and a thin liquid crystal display device can be obtained. The film thickness of the film of the present invention is preferably 20 to 40 μm, and more preferably 22 to 30 μm. When the film of this invention is a laminated film, the range of the total film thickness of a film is the said preferable range.

(Film width)
The film of the present invention preferably has a film width of 1000 mm or more, more preferably 1500 mm or more, and particularly preferably 1800 mm or more.

(ΔRth before and after water contact test)
In the cellulose acylate film of the invention, the absolute value of ΔRth after the water contact test is 5 nm or less, preferably 4 nm or less, more preferably 3 nm or less. Furthermore, it is more preferable that the value of ΔRth is 0 to 3 nm. Such ΔRth is used for adjusting the stretching conditions (residual solvent amount and stretching temperature at the start of stretching) in the production of the cellulose acylate film, or for the aromatic dicarboxylic acid group in the polycondensed ester contained in the cellulose acylate film. This can be achieved by setting the blending amount to 70 mol% or more.

(Re, Rth)
In the film of the present invention, the in-plane retardation and the thickness direction retardation at a wavelength of 550 nm preferably satisfy the following formulas (1) and (2).
Formula (1) 40nm <= Re (550) <= 80nm
(In formula (1), Re (550) represents in-plane retardation at a wavelength of 550 nm.)
Formula (2) 100 nm ≦ Rth (550) ≦ 300 nm
(In Formula (2), Rth (550) represents retardation in the film thickness direction at a wavelength of 550 nm.)
It is preferable that retardation is developed in such a range from the viewpoint of improving the contrast and blackness change of the liquid crystal display device.
The Re (550) is preferably 40 to 65 nm, and more preferably 45 to 60 nm.
The Rth (550) is preferably 100 to 300 nm, more preferably 100 to 230 nm, and still more preferably 105 to 150 nm.

(Rth / d)
In the present invention, when the film thickness is dnm, Rth / d is 0.0025 or more, and may be 0.0030 or more. High Rth / d means high retardation development. Such high retardation developability can be achieved by adjusting the stretching conditions (residual solvent amount and stretching temperature at the start of stretching) in the production of a cellulose acylate film, or by the fragrance in the polycondensed ester contained in the cellulose acylate film. This can be achieved by setting the amount of the group dicarboxylic acid group to 70 mol% or more.
In addition, the film thickness in this invention says an average film thickness.

  In this specification, Re (λ) and Rth (λ) represent in-plane retardation and retardation in the thickness direction at the wavelength λ, respectively. In the present specification, the wavelength λ is 550 nm unless otherwise specified. Re (λ) is measured by making light having a wavelength of λ nm incident in the normal direction of the film in KOBRA 21ADH (manufactured by Oji Scientific Instruments). Rth (λ) is Re (λ), with the in-plane slow axis (determined by KOBRA 21ADH) as the tilt axis (rotary axis) (in the absence of the slow axis, any direction in the film plane) Is measured in 6 points from the inclined direction in 10 degree steps from the normal direction to 50 degrees on one side with respect to the normal direction of the film. KOBRA 21ADH calculates based on the retardation value, the assumed average refractive index, and the input film thickness value. The retardation value is measured from any two directions with the slow axis as the tilt axis (rotation axis) (in the absence of the slow axis, the arbitrary direction in the film plane is the rotation axis), and the value Rth can also be calculated from the following formula (A) and formula (B) based on the assumed average refractive index and the input film thickness value. Here, as the assumed value of the average refractive index, values in the polymer handbook (John Wiley & Sons, Inc.) and catalogs of various optical films can be used. Those whose average refractive index is not known can be measured with an Abbe refractometer. The average refractive index values of main optical films are exemplified below: cellulose acylate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49), Polystyrene (1.59). The KOBRA 21ADH calculates nx, ny, and nz by inputting the assumed value of the average refractive index and the film thickness. Nz = (nx−nz) / (nx−ny) is further calculated from the calculated nx, ny, and nz.

Here, Re (θ) represents a retardation value in a direction inclined by an angle θ from the normal direction, nx, ny, and nz represent refractive indexes in respective principal axis directions of the refractive index ellipsoid, and d represents a film. Represents thickness.
Rth = ((nx + ny) / 2−nz) × d Formula (B)
At this time, an average refractive index n is required as a parameter, and a value measured by an Abbe refractometer (“Abbe refractometer 2-T” manufactured by Atago Co., Ltd.) was used.

(Internal haze)
The cellulose acylate film of the present invention preferably has an internal haze of 0.05% or less, more preferably 0.04% or less, and more preferably 0.35% or less.
The haze represents a haze value (%) measured according to JIS K7136.
The internal haze of the film of the present invention is obtained by dropping several drops of glycerin on both sides of the obtained cellulose acylate film and sandwiching it from both sides with two 1.3 mm thick glass plates (MICRO SLIDE GLASS product number S9213, manufactured by MATSUNAMI). The value (%) obtained by subtracting the haze measured in a state where several drops of glycerin were dropped between two sheets of glass from the haze value (%) measured in an open state.
The haze of the cellulose acylate film of the present invention was measured using a turbidimeter (NDH2000, Nippon Denshoku Industries Co., Ltd.) in a film that was allowed to stand for 24 hours in an environment of 23 ° C. and 55% relative humidity. It was measured.

  A lower haze is generally preferred. Further, simply reducing the total haze is insufficient for improving the front contrast, and adjusting the inner haze to the above range is preferable from the viewpoint of improving the front contrast of the liquid crystal display device.

(Dimensional change rate)
The film of the present invention more preferably satisfies the following formula (7) in the direction of film conveyance and the direction orthogonal thereto at a dimensional change rate of about 24 hours at 60 ° C. and 90% relative humidity.
−0.5% ≦ {(L′−L0) / L0} × 100 ≦ 0.5% (7)
The L0 represents the film length after conditioning for 2 hours or more in an atmosphere of 25 ° C. and a relative humidity of 60%, and L ′ is 24 hours at 60 ° C. and 90% relative humidity, and further conditioned for 2 hours. Represents film length.
When the dimensional change rate is within the range of the formula (7), the saponification treatment hardly causes dimensional change of the film, so that wrinkles and air can be prevented from being mixed in the polarizing plate bonding process. The dimensional change rate is more preferably −0.4 to 0.4%, and particularly preferably −0.2 to 0.2%.

<Method for producing cellulose acylate film>
The cellulose acylate film of the present invention can be widely used for producing a known cellulose ester film, and is preferably produced by a solvent cast method. In the solvent cast method, a film can be produced using a solution (dope) obtained by dissolving cellulose acylate in an organic solvent.
The organic solvent is a solvent selected from ethers having 3 to 12 carbon atoms, ketones having 3 to 12 carbon atoms, esters having 3 to 12 carbon atoms, and halogenated hydrocarbons having 1 to 6 carbon atoms. It is preferable to contain. The ether, ketone and ester may have a cyclic structure. A compound having two or more functional groups of ether, ketone and ester (that is, —O—, —CO— and —COO—) can also be used as the organic solvent. The organic solvent may have another functional group such as an alcoholic hydroxyl group. In the case of an organic solvent having two or more types of functional groups, the number of carbon atoms may be within the specified range of the compound having any functional group.

Examples of the ether having 3 to 12 carbon atoms include diisopropyl ether, dimethoxymethane, dimethoxyethane, 1,4-dioxane, 1,3-dioxolane, tetrahydrofuran, anisole and phenetole.
Examples of ketones having 3 to 12 carbon atoms include acetone, methyl ethyl ketone, diethyl ketone, diisobutyl ketone, cyclohexanone and methylcyclohexanone.
Examples of the esters having 3 to 12 carbon atoms include ethyl formate, propyl formate, pentyl formate, methyl acetate, ethyl acetate and pentyl acetate.
Examples of the organic solvent having two or more kinds of functional groups include 2-ethoxyethyl acetate, 2-methoxyethanol and 2-butoxyethanol.
The number of carbon atoms of the halogenated hydrocarbon is preferably 1 or 2, and most preferably 1. The halogen of the halogenated hydrocarbon is preferably chlorine. The proportion of halogen atoms substituted by halogen in the halogenated hydrocarbon is preferably 25 to 75 mol%, more preferably 30 to 70 mol%, and more preferably 35 to 65 mol%. More preferably, it is most preferable that it is 40-60 mol%. Methylene chloride is a representative halogenated hydrocarbon.
Two or more organic solvents may be mixed and used.

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

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

A solution can also be prepared by a cooling dissolution method. In the cooling dissolution method, cellulose acylate can be dissolved in an organic solvent that is difficult to dissolve by a normal dissolution method. In addition, even if it is a solvent which can melt | dissolve a cellulose acylate with a normal melt | dissolution method, there exists an effect that a uniform solution can be obtained rapidly according to a cooling melt | dissolution method.
In the cooling dissolution method, first, cellulose acylate is gradually added to an organic solvent with stirring at room temperature. The amount of cellulose acylate is preferably adjusted so as to be contained in the mixture in an amount of 10 to 40% by mass. The amount of cellulose acylate is more preferably 10 to 30% by mass. Furthermore, you may add the arbitrary additive mentioned later in a mixture.
The mixture is then cooled to -100 to -10 ° C (preferably -80 to -10 ° C, more preferably -50 to -20 ° C, most preferably -50 to -30 ° C). The cooling can be performed, for example, in a dry ice / methanol bath (−75 ° C.) or a cooled diethylene glycol solution (−30 to −20 ° C.). When cooled in this manner, the mixture of cellulose acylate and organic solvent solidifies.

The cooling rate is preferably 4 ° C./min or more, more preferably 8 ° C./min or more, and most preferably 12 ° C./min or more. The faster the cooling rate, the better. However, 10,000 ° C./second is the theoretical upper limit, 1000 ° C./second is the technical upper limit, and 100 ° C./second is the practical upper limit. The cooling rate is a value obtained by dividing the difference between the temperature at the start of cooling and the final cooling temperature by the time from the start of cooling to the final cooling temperature.
Furthermore, when this is heated to 0 to 200 ° C. (preferably 0 to 150 ° C., more preferably 0 to 120 ° C., most preferably 0 to 50 ° C.), cellulose acylate dissolves in the organic solvent. The temperature can be raised by simply leaving it at room temperature or in a warm bath. The heating rate is preferably 4 ° C./min or more, more preferably 8 ° C./min or more, and most preferably 12 ° C./min or more. The higher the heating rate, the better. However, 10,000 ° C./second is the theoretical upper limit, 1000 ° C./second is the technical upper limit, and 100 ° C./second is the practical upper limit. The heating rate is the value obtained by dividing the difference between the temperature at the start of heating and the final heating temperature by the time from the start of heating until the final heating temperature is reached. is there.

A uniform solution is obtained as described above. If the dissolution is insufficient, the cooling and heating operations may be repeated. Whether or not the dissolution is sufficient can be determined by merely observing the appearance of the solution by visual observation.
In the cooling dissolution method, it is desirable to use a sealed container in order to avoid moisture mixing due to condensation during cooling. In the cooling and heating operation, when the pressure is applied during cooling and the pressure is reduced during heating, the dissolution time can be shortened. In order to perform pressurization and decompression, it is desirable to use a pressure-resistant container.
In addition, according to differential scanning calorimetry (DSC), a 20% by mass solution of cellulose acylate (total acetyl substitution degree: 60.9%, viscosity average polymerization degree: 299) dissolved in methyl acetate by the cooling dissolution method is In the vicinity of 33 ° C., there exists a quasi-phase transition point between a sol state and a gel state, and a uniform gel state is obtained below this temperature. Therefore, this solution needs to be stored at a temperature equal to or higher than the pseudo phase transition temperature, preferably about the gel phase transition temperature plus about 10 ° C. However, this pseudo phase transition temperature varies depending on the total acetyl substitution degree, viscosity average polymerization degree, solution concentration, and organic solvent used in cellulose acylate.

From the prepared cellulose acylate solution (dope), a cellulose acylate film can be produced by a solvent cast method.
The dope is cast on a drum or band, and the solvent is evaporated to form a film. The concentration of the dope before casting is preferably adjusted so that the solid content is 18 to 35% by mass. The surface of the drum or band is preferably finished in a mirror state. For casting and drying methods in the solvent casting method, U.S. Pat. Nos. 2,336,310, 2,367,603, 2,429,078, 2,429,297, 2,429,978, 2,607,704, 2,739,69, British Patent 6,407,331, No. 736892, JP-B Nos. 45-4554, 49-5614, JP-A-60-176834, No. 60-203430, and No. 62-1115035.

The dope is preferably cast on a drum or band having a surface temperature of 10 ° C. or less. After casting, it is preferable to dry it by applying air for 2 seconds or more. The obtained film can be peeled off from the drum or band and further dried with high-temperature air whose temperature is successively changed from 100 ° C. to 160 ° C. to evaporate the residual solvent. The above method is described in Japanese Patent Publication No. 5-17844. According to this method, it is possible to shorten the time from casting to stripping. In order to carry out this method, it is necessary for the dope to gel at the surface temperature of the drum or band during casting.
In order to improve mechanical properties or increase the drying speed, cellulose ester film can be added. As the plasticizer, phosphoric acid ester or carboxylic acid ester is used. Examples of phosphate esters include triphenyl phosphate (TPP) and tricresyl phosphate (TCP). Representative examples of the carboxylic acid ester include phthalic acid esters and citric acid esters. Examples of phthalic acid esters include dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), dioctyl phthalate (DOP), diphenyl phthalate (DPP) and diethyl hexyl phthalate (DEHP). Examples of citrate esters include triethyl O-acetylcitrate (OACTE) and tributyl O-acetylcitrate (OACTB). Examples of other carboxylic acid esters include butyl oleate, methylacetyl ricinoleate, dibutyl sebacate, and various trimellitic acid esters. Phthalate plasticizers (DMP, DEP, DBP, DOP, DPP, DEHP) are preferably used. DEP and DPP are particularly preferred. The addition amount of the plasticizer is preferably 0.1 to 25% by mass of the amount of cellulose acylate, more preferably 1 to 20% by mass, and most preferably 3 to 15% by mass.

  A degradation inhibitor (for example, an antioxidant, a peroxide decomposer, a radical inhibitor, a metal deactivator, an acid scavenger, an amine) may be added to the cellulose acylate film. The deterioration inhibitors are described in JP-A-3-199201, JP-A-597073, JP-A-5-194789, JP-A-5-271471, and JP-A-6-107854. The amount of the deterioration inhibitor added is 0.01 to 1 of the solution (dope) to be prepared from the viewpoint that the effect of addition of the deterioration inhibitor is manifested and that the deterioration inhibitor is prevented from bleeding out on the film surface. It is preferable that it is mass%, and it is further more preferable that it is 0.01-0.2 mass%. Examples of particularly preferred deterioration inhibitors include butylated hydroxytoluene (BHT) and tribenzylamine (TBA).

  A method for drying a web that has been dried on a drum or belt and peeled off will be described. The web peeled at the peeling position immediately before the drum or belt makes one round is conveyed by alternately passing through a group of rolls arranged in a staggered manner, or both ends of the peeled web are gripped by clips or the like. It is transported by a non-contact transport method. Drying is performed by a method of applying wind at a predetermined temperature to both sides of the web (film) being conveyed or a method using a heating means such as a microwave. Since rapid drying may impair the flatness of the film to be formed, it is preferable to dry at a temperature at which the solvent does not foam in the initial stage of drying, and to dry at a high temperature after the drying has progressed. In the drying process after peeling from the support, the film tends to shrink in the longitudinal direction or the width direction by evaporation of the solvent. Shrinkage increases with drying at higher temperatures. Drying while suppressing this shrinkage as much as possible is preferable for improving the flatness of the finished film. From this point, for example, as shown in Japanese Patent Laid-Open No. 62-46625, a method in which all or part of the drying process is performed while holding the width at both ends of the web with clips or pins in the width direction. (Tenter method) is preferable. It is preferable that the drying temperature in the said drying process is 100-145 degreeC. Although the drying temperature, the amount of drying air, and the drying time differ depending on the solvent used, it may be appropriately selected according to the type and combination of solvents used. In the production of the cellulose acylate film, the web (film) peeled from the support is stretched when the residual solvent amount in the web is 35 to 65 mass% residual solvent (preferably 35 to 40 mass%). By setting such a residual solvent amount and stretching at a low temperature as described later, the internal haze can be lowered.

The amount of residual solvent can be expressed by the following formula.
Residual solvent amount (% by mass) = {(MN) / N} × 100
Here, M is the mass of the web at an arbitrary point in time, and N is the mass when the web of which M is measured is dried at 110 ° C. for 3 hours. If the amount of residual solvent in the web is too large, the effect of stretching cannot be obtained, and if it is too small, stretching becomes extremely difficult and the web may break.

(Stretching)
The film of the present invention is preferably stretched with a residual solvent amount of 35 to 65% by mass. The stretching temperature is more preferably Tg-70 to Tg-30 ° C (Tg is the glass transition temperature (unit: ° C) of the cellulose acylate film). In this invention, since it extends | stretches at such a low temperature, retardation development property can be improved.
In the present invention, it is preferable that the cellulose acylate film is conveyed and stretched with a tension of 100 N / m or less while gripping both ends of the cellulose acylate film. The tension is preferably 70 N / m or less. Moreover, although a lower limit is not specifically defined, 40 N / m or more is preferable.

  The draw ratio is preferably 10 to 50%, and more preferably 15 to 40%. In addition, the stretching may be performed in the longitudinal direction, in the lateral direction, or in both directions, and is preferably performed at least in the lateral direction. By setting the draw ratio to 10% or more, Re can be expressed more appropriately, and the bowing can be improved. Moreover, haze can be reduced by making a draw ratio into 50% or less.

  As a winder for winding the obtained film, a commonly used winder can be used, such as a constant tension method, a constant torque method, a taper tension method, a program tension control method with a constant internal stress, etc. It can be wound up by the winding method. In the optical film roll obtained as described above, the slow axis direction of the film is preferably ± 2 ° with respect to the winding direction (longitudinal direction of the film), and further within the range of ± 1 °. Preferably there is. Alternatively, it is preferably ± 2 degrees with respect to the direction perpendicular to the winding direction (film width direction), and more preferably within a range of ± 1 degree. In particular, the slow axis direction of the film is preferably within ± 0.1 degrees with respect to the winding direction (longitudinal direction of the film). Alternatively, it is preferably within ± 0.1 degrees with respect to the width direction of the film.

<Polarizing plate>
The cellulose acylate film of the present invention functions as a retardation film, but is preferably incorporated as a protective film for a polarizing plate.
That is, the polarizing plate of the present invention includes a polarizer and at least one cellulose acylate film of the present invention as a first polarizing plate protective film on at least one side of the polarizer, and a second side on the other side of the polarizer. A polarizing plate protective film. Hereinafter, the polarizing plate of the present invention will be described.

Like the film of the present invention, the polarizing plate of the present invention is not only a polarizing plate in the form of a film piece cut into a size that can be incorporated into a liquid crystal display device as it is, but also in a long form by continuous production. The polarizing plate of the aspect (for example, aspects with roll length 2500m or more, 3900m or more) wound up in roll shape is also contained. In order to use for a large-screen liquid crystal display device, the width of the polarizing plate is preferably 1470 mm or more as described above.
In the polarizing plate of this invention, it is preferable that the film thickness of a polarizer is 3-20 micrometers, and it is more preferable that it is 5-20 micrometers.
In the polarizing plate of the present invention, at least one side of the first polarizing plate protective film includes the cellulose acylate film of the present invention, but as the other second polarizing plate protective film, a known cellulose acylate film is used. Can do. The thickness of the other second polarizing plate protective film is preferably 10 to 40 μm, and more preferably 10 to 29 μm.
Furthermore, the total polarizing plate thickness of the present invention is preferably 40 to 100 μm, more preferably 50 to 100 μm, and particularly preferably 65 to 95 μm. The total thickness here is intended to include an adhesive layer for bonding the polarizing plate protective film in addition to the polarizing plate and the polarizing plate protective film bonded to both sides of the polarizer.
The specific configuration of the polarizing plate of the present invention is not particularly limited, and a known configuration can be employed. For example, the configuration described in FIG. 6 of JP-A-2008-262161 can be employed.

<Second polarizing plate protective film>
A film made of a thermoplastic resin other than the cellulose acylate film can also be used as the second polarizing plate protective film. Optimal thermoplastic resins include (meth) acrylic resins, polycarbonate resins, polystyrene resins, olefin resins, glutaric anhydride resins, glutarimide resins, etc., and these resins and their multiple types (However, the (meth) acrylic resin includes a lactone ring-containing polymer).

In particular, it is preferable to use a film having a moisture permeability (40 ° C./90% RH) defined by JISZ0208 of 100 g / m ² · 24 hr or less. If the water vapor transmission rate is 100 g / m ² · 24 hr, the entry of water into the polarizer and the first polarizing plate protective film can be delayed, and the occurrence of unevenness, which is a problem of the present invention, can be reduced. Examples of these films include polyester films, cycloolefin films, polycarbonate films, and polyolefin films.

  The (meth) acrylic resin is a concept including both a methacrylic resin and an acrylic resin. The (meth) acrylic resin also includes acrylate / methacrylate derivatives, particularly acrylate / methacrylate (co) polymers.

((Meth) acrylic resin)
The repeating structural unit of the (meth) acrylic acid resin is not particularly limited. The (meth) acrylic resin preferably has a repeating structural unit derived from a (meth) acrylic acid ester monomer as a repeating structural unit.

  The (meth) acrylic acid resin further polymerizes at least one selected from a hydroxyl group-containing monomer, an unsaturated carboxylic acid and a monomer represented by the following general formula (201) as a repeating structural unit. It may contain a repeating structural unit constructed by

Formula (201)
CH ₂ = C (X) R ²⁰¹

(In the formula, R ²⁰¹ represents a hydrogen atom or a methyl group, and X represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group, a —CN group, a —CO—R ²⁰² group, or —O—CO—R. ²⁰³ represents a group, and R ²⁰² and R ²⁰³ represent a hydrogen atom or an organic residue having 1 to 20 carbon atoms.)

The (meth) acrylic acid ester is not particularly limited, and examples thereof include methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, cyclohexyl acrylate, and benzyl acrylate. Acrylic acid esters; methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, cyclohexyl methacrylate, methacrylic acid esters such as benzyl methacrylate; These may be used alone or in combination of two or more. Among these, methyl methacrylate is particularly preferable from the viewpoint of excellent heat resistance and transparency.
When the (meth) acrylic acid ester is used, the content ratio in the monomer component to be subjected to the polymerization step is preferably 10 to 100% by weight, more preferably 10%, in order to sufficiently exhibit the effects of the present invention. -100% by weight, more preferably 40-100% by weight, particularly preferably 50-100% by weight.

The hydroxyl group-containing monomer is not particularly limited. For example, 2- (hydroxyalkyl) acrylic acid ester such as α-hydroxymethylstyrene, α-hydroxyethylstyrene, methyl 2- (hydroxyethyl) acrylate; 2 2- (hydroxyalkyl) acrylic acid such as-(hydroxyethyl) acrylic acid; and the like. These may be used alone or in combination of two or more.
In the case of using the hydroxyl group-containing monomer, the content ratio in the monomer component to be subjected to the polymerization step is preferably 0 to 30% by weight, more preferably 0 to 0% in order to sufficiently exert the effects of the present invention. It is 20% by weight, more preferably 0 to 15% by weight, particularly preferably 0 to 10% by weight.

Examples of the unsaturated carboxylic acid include acrylic acid, methacrylic acid, crotonic acid, α-substituted acrylic acid, α-substituted methacrylic acid and the like. These may be used alone or in combination of two or more. You may use together. Among these, acrylic acid and methacrylic acid are preferable in that the effects of the present invention are sufficiently exhibited.
When the unsaturated carboxylic acid is used, the content ratio in the monomer component to be subjected to the polymerization step is preferably 0 to 30% by weight, more preferably 0 to 20%, in order to sufficiently exhibit the effects of the present invention. % By weight, more preferably 0-15% by weight, particularly preferably 0-10% by weight.

Examples of the monomer represented by the general formula (201) include styrene, vinyl toluene, α-methyl styrene, acrylonitrile, methyl vinyl ketone, ethylene, propylene, vinyl acetate, and the like. You may use, and may use 2 or more types together. Among these, styrene and α-methylstyrene are particularly preferable in that the effects of the present invention are sufficiently exhibited.
When the monomer represented by the general formula (201) is used, the content ratio in the monomer component to be subjected to the polymerization step is preferably 0 to 30% in order to sufficiently exhibit the effects of the present invention. %, More preferably 0 to 20% by weight, still more preferably 0 to 15% by weight, particularly preferably 0 to 10% by weight.

The monomer component may form a lactone ring after polymerization. In that case, it is preferable to polymerize the monomer component to obtain a polymer having a hydroxyl group and an ester group in the molecular chain.
As a polymerization reaction form for polymerizing the monomer component to obtain a polymer having a hydroxyl group and an ester group in the molecular chain, a polymerization form using a solvent is preferable, and solution polymerization is particularly preferable. .
For example, a lactone ring structure described in JP 2007-316366 A, JP 2005-189623 A, WO 2007/032304, WO 2006/025445 is also preferable. It is.

(Lactone ring-containing polymer)
The lactone ring-containing polymer is not particularly limited as long as it has a lactone ring, but preferably has a lactone ring structure represented by the following general formula (401).

General formula (401):

In the general formula (401), R ⁴⁰¹ , R ⁴⁰² and R ⁴⁰³ each independently represent a hydrogen atom or an organic residue having 1 to 20 carbon atoms, and the organic residue may contain an oxygen atom. . Here, the organic residue having 1 to 20 carbon atoms is preferably a methyl group, an ethyl group, an isopropyl group, an n-butyl group, a t-butyl group, or the like.

  The content ratio of the lactone ring structure represented by the general formula (401) in the structure of the lactone ring-containing polymer is preferably 5 to 90% by mass, more preferably 10 to 70% by mass, and still more preferably 10 to 60% by mass. %, Particularly preferably 10 to 50% by mass. By setting the content ratio of the lactone ring structure to 5% by mass or more, the heat resistance and surface hardness of the obtained polymer tend to be improved, and by setting the content ratio of the lactone ring structure to 90% by mass or less. The moldability of the obtained polymer tends to be improved.

  The method for producing the lactone ring-containing polymer is not particularly limited, but preferably, after obtaining a polymer (p) having a hydroxyl group and an ester group in the molecular chain by a polymerization step, the obtained polymer ( It is obtained by carrying out a lactone cyclization condensation step for introducing a lactone ring structure into the polymer by heat-treating p).

  The mass average molecular weight of the lactone ring-containing polymer is preferably 1,000 to 2,000,000, more preferably 5,000 to 1,000,000, still more preferably 10,000 to 500,000, particularly preferably. 50,000 to 500,000.

  The lactone ring-containing polymer has a mass reduction rate within a range of 150 to 300 ° C. in dynamic TG measurement, preferably 1% or less, more preferably 0.5% or less, and still more preferably 0.3% or less. It is good. As a method for measuring dynamic TG, the method described in JP-A-2002-138106 can be used.

  Since the lactone ring-containing polymer has a high cyclization condensation reaction rate, there is little dealcoholization reaction in the production process of the molded product, and bubbles and silver stripes (silver streaks) are formed in the molded product after molding due to the alcohol. The disadvantage of entering can be avoided. Furthermore, since the lactone ring structure is sufficiently introduced into the polymer due to a high cyclization condensation reaction rate, the obtained lactone ring-containing polymer has high heat resistance.

  The lactone ring-containing polymer has a coloring degree (YI) of preferably 6 or less, more preferably 3 or less, still more preferably 2 or less, and particularly preferably 1 or less when a chloroform solution having a concentration of 15% by mass is used. . If the degree of coloring (YI) is 6 or less, problems such as loss of transparency due to coloring are unlikely to occur, and therefore, it can be preferably used in the present invention.

  The lactone ring-containing polymer has a 5% mass reduction temperature in thermal mass spectrometry (TG) of preferably 330 ° C. or higher, more preferably 350 ° C. or higher, and still more preferably 360 ° C. or higher. The 5% mass reduction temperature in thermal mass spectrometry (TG) is an indicator of thermal stability, and by setting it to 330 ° C. or higher, sufficient thermal stability tends to be exhibited. The thermal mass spectrometry can use the apparatus for measuring the dynamic TG.

  The lactone ring-containing polymer has a glass transition temperature (Tg) of preferably 115 ° C. or higher, more preferably 125 ° C. or higher, further preferably 130 ° C. or higher, particularly preferably 135 ° C. or higher, and most preferably 140 ° C. or higher. .

  The total amount of residual volatile components contained in the lactone ring-containing polymer is preferably 5,000 ppm or less, more preferably 2,000 ppm or less, still more preferably 1,500 ppm, and particularly preferably 1,000 ppm. If the total amount of residual volatile components is 5,000 ppm or less, it is preferable because coloring defects due to alteration during molding, foaming, and molding defects such as silver streak are unlikely to occur.

  The lactone ring-containing polymer has a total light transmittance of 85% or more, more preferably 88% or more, and still more preferably measured by a method based on ASTM-D-1003 for a molded product obtained by injection molding. 90% or more. The total light transmittance is an index of transparency, and when it is 85% or more, the transparency tends to be improved.

In the case of a polymerization form using a solvent, the polymerization solvent is not particularly limited. For example, aromatic hydrocarbon solvents such as toluene, xylene, and ethylbenzene; ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone; ether solvents such as tetrahydrofuran Etc., and only one of these may be used, or two or more may be used in combination.
In the first aspect of the production method of the present invention, the (meth) acrylic resin is dissolved in an organic solvent and cast by solution casting. Therefore, the organic solvent at the time of synthesizing the (meth) acrylic resin is There is no limitation as compared with the case of performing melt film formation, and synthesis may be performed using an organic solvent having a high boiling point.

During the polymerization reaction, a polymerization initiator may be added as necessary. Although it does not specifically limit as a polymerization initiator, For example, cumene hydroperoxide, diisopropylbenzene hydroperoxide, di-t-butyl peroxide, lauroyl peroxide, benzoyl peroxide, t-butylperoxyisopropyl carbonate, t-amyl Organic peroxides such as peroxy-2-ethylhexanoate; 2,2′-azobis (isobutyronitrile), 1,1′-azobis (cyclohexanecarbonitrile), 2,2′-azobis (2, Azo compounds such as 4-dimethylvaleronitrile), and the like. These may be used alone or in combination of two or more. The amount of the polymerization initiator used is not particularly limited as long as it is appropriately set according to the combination of the monomers used and the reaction conditions.
The weight average molecular weight of the polymer can be adjusted by adjusting the amount of the polymerization initiator.

  When performing the polymerization, it is preferable to control the concentration of the produced polymer in the polymerization reaction mixture to be 50% by weight or less in order to suppress gelation of the reaction solution. Specifically, when the concentration of the produced polymer in the polymerization reaction mixture exceeds 50% by weight, it is preferable that the polymerization solvent is appropriately added to the polymerization reaction mixture and controlled to be 50% by weight or less. . The concentration of the produced polymer in the polymerization reaction mixture is more preferably 45% by weight or less, still more preferably 40% by weight or less.

  The form in which the polymerization solvent is appropriately added to the polymerization reaction mixture is not particularly limited, and the polymerization solvent may be added continuously or intermittently. By controlling the concentration of the produced polymer in the polymerization reaction mixture in this way, the gelation of the reaction solution can be more sufficiently suppressed. The polymerization solvent to be added may be the same type of solvent used during the initial charging of the polymerization reaction or may be a different type of solvent, but is the same as the solvent used during the initial charging of the polymerization reaction. It is preferable to use different types of solvents. Further, the polymerization solvent to be added may be only one type of solvent or a mixed solvent of two or more types.

Examples of acrylic resins and (meth) acrylic acid derivatives and other copolymerizable monomers that can be used in the present invention include JP2009-122664A, JP2009-139661A, JP2009-139754A, Those described in JP-A 2009-294262, International Publication No. 2009/054376, and the like can also be used. In addition, these do not limit this invention, These can be used individually or in combination of 2 or more types.
When two or more types of acrylic resins are used, it is preferable to use at least one type having the above structure.

  The mass average molecular weight Mw of the acrylic resin used in the present invention is preferably 80,000 or more. If the mass average molecular weight Mw of an acrylic resin is 80000 or more, mechanical strength is high and it is excellent in the handling ability at the time of film manufacture. In this respect, the acrylic resin preferably has a mass average molecular weight Mw of 100,000 or more. Further, from the viewpoint of improving compatibility with the cellulose ester, the acrylic resin has a mass average molecular weight Mw of preferably 3000000 or less, and more preferably 2000000 or less.

A commercially available thing can also be used as an acrylic resin used for this invention. For example, Delpet 60N, 80N (Asahi Kasei Chemicals Co., Ltd.), Dianal BR80, BR85, BR88, BR102 (Mitsubishi Rayon Co., Ltd.), KT75 (Electrochemical Industry Co., Ltd.) and the like can be mentioned.
Two or more acrylic resins can be used in combination.

(Polyester resin)
As the polyester resin, polyethylene terephthalate and polyethylene naphthalate are preferable. Additives can be added and used to control the peel force and toughness as appropriate.

(Polycarbonate resin)
The thermoplastic resin that can be used in the present invention can be used by adding an additive to the polycarbonate resin to appropriately control the peeling force and toughness. As the polycarbonate film, commercially available products include Pure Ace, Pure Ace WR (manufactured by Teijin Chemicals Ltd.), and Elmec (manufactured by Kaneka Corp.).
(Polystyrene resin)
The thermoplastic resin that can be used in the present invention can be used by appropriately adding an additive to the polystyrene resin to control the peeling force and toughness.

(Cyclic polyolefin resin)
As the thermoplastic resin that can be used in the present invention, a cyclic polyolefin resin can be used. Here, the cyclic polyolefin resin represents a polymer resin having a cyclic olefin structure.
Examples of the polymer resin having a cyclic olefin structure used in the present invention include (1) a norbornene polymer, (2) a monocyclic olefin polymer, (3) a cyclic conjugated diene polymer, (4) There are vinyl alicyclic hydrocarbon polymers and hydrides of (1) to (4).
Preferred polymers for the present invention are addition (co) polymer cyclic polyolefin resins containing at least one repeating unit represented by the following general formula (IIX) and, if necessary, a repeating represented by the general formula (IX) An addition (co) polymer cyclic polyolefin-based resin further comprising at least one unit. Further, a ring-opening (co) polymer containing at least one cyclic repeating unit represented by the general formula (IIIX) can also be suitably used.

Formula (IX)

Formula (IIX)

Formula (IIIX)

In formulas (IX) to (IIIX), m represents an integer of 0 to 4. R ^{1 to} R ⁶ are a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms, X ^{1 to} X ³ and Y ^{1 to} Y ³ are a hydrogen atom, a hydrocarbon group having 1 to 10 carbon atoms, a halogen atom, and a halogen atom. substituted hydrocarbon group having 1 to 10 carbon _{atoms, - (CH 2) n COOR} 11, - (CH 2) n OCOR 12, - (CH 2) n NCO, - (CH 2) n NO 2, - ( _{CH 2) n CN, - (} CH 2) n CONR 13 R 14, - (CH 2) n NR 13 R 14, - (CH 2) n OZ, - (CH 2) n W, or X ¹ and Y ¹ Alternatively, (—CO) ₂ O and (—CO) ₂ NR ¹⁵ composed of X ² and Y ² or X ³ and Y ³ are shown. R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , and R ¹⁵ are hydrogen atoms, hydrocarbon groups having 1 to 20 carbon atoms, Z is a hydrocarbon group or a hydrocarbon group substituted with a halogen, and W is SiR ¹⁶ _p. D _3-p (R ¹⁶ is a hydrocarbon group having 1 to 10 carbon atoms, D is a halogen atom, —OCOR ¹⁶ or —OR ¹⁶ , p is an integer of 0 to 3), n is an integer of 0 to 10 Show.

Norbornene-based polymer hydrides are disclosed in JP-A-1-240517, JP-A-7-196736, JP-A-60-26024, JP-A-62-19807, JP-A-2003-115767, or As disclosed in Japanese Patent Application Laid-Open No. 2004-309979 and the like, the polycyclic unsaturated compound is produced by addition polymerization or metathesis ring-opening polymerization and then hydrogenation. In the norbornene-based polymer used in the present invention, R ^{5 to} R ⁶ are preferably a hydrogen atom or —CH ₃ , X ³ and Y ³ are preferably a hydrogen atom, Cl, —COOCH ₃ , and other groups are appropriately selected. The This norbornene-based resin is sold under the trade name Arton G or Arton F by JSR Corporation, and from Zeon Corporation, Zeonor ZF14, ZF16, Zeonex 250 or Zeonex. They are commercially available under the trade name 280 and can be used.

  Norbornene-based addition (co) polymers are disclosed in JP-A No. 10-7732, JP-T-2002-504184, U.S. Published Patent No. 200429129157A1 or WO2004 / 070463A1. It can be obtained by addition polymerization of norbornene-based polycyclic unsaturated compounds. If necessary, norbornene-based polycyclic unsaturated compounds and ethylene, propylene, butene; conjugated dienes such as butadiene and isoprene; nonconjugated dienes such as ethylidene norbornene; acrylonitrile, acrylic acid, methacrylic acid, maleic anhydride It is also possible to carry out addition polymerization with linear diene compounds such as acid, acrylic acid ester, methacrylic acid ester, maleimide, vinyl acetate and vinyl chloride. This norbornene-based addition (co) polymer is marketed by Mitsui Chemicals, Inc. under the name of Apel, and has different glass transition temperatures (Tg) such as APL8008T (Tg70 ° C), APL6013T (Tg125 ° C) or APL6015T ( Grades such as Tg145 ° C). Pellets such as TOPAS 8007, 6013, and 6015 are sold by Polyplastics Co., Ltd. Further, Appear 3000 is sold by Ferrania.

  In the present invention, the glass transition temperature (Tg) of the cyclic polyolefin-based resin is not limited, but a high-Tg cyclic polyolefin resin such as 200 to 400 ° C. can also be used.

(Glutaric anhydride resin)
As the thermoplastic resin that can be used in the present invention, a glutaric anhydride resin can be used. Here, the glutaric anhydride resin represents a polymer resin having a glutaric anhydride unit.

  The polymer having a glutaric anhydride unit preferably has a glutaric anhydride unit represented by the following general formula (402) (hereinafter referred to as a glutaric anhydride unit).

General formula (402):

In General Formula (402), R ³¹ and R ³² each independently represent a hydrogen atom or an organic residue having 1 to 20 carbon atoms. The organic residue may contain an oxygen atom. R ³¹ and R ³² particularly preferably represent the same or different hydrogen atoms or alkyl groups having 1 to 5 carbon atoms.

  The polymer having glutaric anhydride units is preferably an acrylic copolymer containing glutaric anhydride units. The acrylic thermoplastic copolymer preferably has a glass transition temperature (Tg) of 120 ° C. or higher from the viewpoint of heat resistance.

  As content of the glutaric anhydride unit with respect to an acrylic thermoplastic copolymer, 5-50 mass% is preferable, More preferably, it is 10-45 mass%. When the content is 5% by mass or more, more preferably 10% by mass or more, an effect of improving heat resistance can be obtained, and further an effect of improving weather resistance can be obtained.

The acrylic thermoplastic copolymer preferably further includes a repeating unit based on an unsaturated carboxylic acid alkyl ester. As the repeating unit based on the unsaturated carboxylic acid alkyl ester, for example, those represented by the following general formula (403) are preferred.
Formula _{(403): - [CH 2} -C (R 41) (COOR 42)] -

In General Formula (403), R ⁴¹ represents hydrogen or an alkyl group having 1 to 5 carbon atoms, and R ⁴² ) represents an aliphatic or alicyclic hydrocarbon group having 1 to 6 carbon atoms, or one or more carbon atoms inclusive. Represents an aliphatic or alicyclic hydrocarbon group having 1 to 6 carbon atoms substituted by the number of hydroxyl groups or halogen.

The monomer corresponding to the repeating unit represented by the general formula (403) is represented by the following general formula (404).
Formula _{(404): CH 2 = C} (R 41) (COOR 42)

  Preferred examples of such monomers include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, (meth) acrylic acid. t-butyl, n-hexyl (meth) acrylate, cyclohexyl (meth) acrylate, chloromethyl (meth) acrylate, 2-chloroethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, (meth ) 3-hydroxypropyl acrylate, 2,3,4,5,6-pentahydroxyhexyl (meth) acrylate and 2,3,4,5-tetrahydroxypentyl (meth) acrylate, among others, methacryl Methyl acid is most preferably used. These may be used individually by 1 type, or may use 2 or more types together.

  The content of the unsaturated carboxylic acid alkyl ester unit relative to the acrylic thermoplastic copolymer is preferably 50 to 95% by mass, more preferably 55 to 90% by mass. An acrylic thermoplastic copolymer having a glutaric anhydride unit and an unsaturated carboxylic acid alkyl ester unit, for example, polymerizes a copolymer having an unsaturated carboxylic acid alkyl ester unit and an unsaturated carboxylic acid unit. It can be obtained by cyclization.

As an unsaturated carboxylic acid unit, what is represented, for example by the following general formula (405) is preferable.
Formula _{(405): - [CH 2} -C (R 51) (COOH)] -
Here, R ⁵¹ represents hydrogen or an alkyl group having 1 to 5 carbon atoms.

Preferred specific examples of the monomer for deriving the unsaturated carboxylic acid unit include a compound represented by the following general formula (406), which is a monomer corresponding to the repeating unit represented by the general formula (405), and Examples thereof include maleic acid and a hydrolyzate of maleic anhydride, and acrylic acid and methacrylic acid are preferable, and methacrylic acid is more preferable in terms of excellent thermal stability.
Formula _{(406): CH 2 = C} (R 51) (COOH)

  These may be used individually by 1 type, or may use 2 or more types together. As described above, an acrylic thermoplastic copolymer having a glutaric anhydride unit and an unsaturated carboxylic acid alkyl ester-based unit is, for example, a copolymer having an unsaturated carboxylic acid alkyl ester-based unit and an unsaturated carboxylic acid unit. Since the polymer can be obtained by cyclization of the polymer, it may have an unsaturated carboxylic acid unit in its constituent unit.

  As content of the unsaturated carboxylic acid unit with respect to said acrylic type thermoplastic copolymer, 10 mass% or less is preferable, More preferably, it is 5 mass% or less. By setting the content to 10% by mass or less, it is possible to prevent a decrease in colorless transparency and retention stability.

  The acrylic thermoplastic copolymer may have other vinyl monomer units that do not contain an aromatic ring as long as the effects of the present invention are not impaired. Specific examples of other vinyl monomer units that do not contain an aromatic ring include the corresponding monomers: vinyl cyanide monomers such as acrylonitrile, methacrylonitrile, ethacrylonitrile; allyl glycidyl ether Maleic anhydride, itaconic anhydride; N-methylmaleimide, N-ethylmaleimide, N-cyclohexylmaleimide, acrylamide, methacrylamide, N-methylacrylamide, butoxymethylacrylamide, N-propylmethacrylamide; aminoethyl acrylate, acrylic Propylaminoethyl acid, dimethylaminoethyl methacrylate, ethylaminopropyl methacrylate, cyclohexylaminoethyl methacrylate; N-vinyldiethylamine, N-acetylvinylamine, allylamine, methallylamino , N- methyl-allyl amine; 2-isopropenyl - oxazoline, 2-vinyl - oxazoline, 2-acryloyl - oxazoline, and the like. These may be used alone or in combination of two or more.

  As content of the other vinyl-type monomer unit which does not contain an aromatic ring with respect to said acrylic type thermoplastic copolymer, 35 mass% or less is preferable.

  For vinyl monomer units containing an aromatic ring (N-phenylmaleimide, phenylaminoethyl methacrylate, p-glycidylstyrene, p-aminostyrene, 2-styryl-oxazoline, etc.), they have scratch resistance and weather resistance. Since there exists a tendency to reduce, it is preferable to keep it as 1 mass% or less as content with respect to the said acrylic thermoplastic copolymer.

(Glutarimide resin)
As the thermoplastic resin that can be used in the present invention, a glutarimide resin can be used. Here, the glutarimide resin represents a polymer resin having a glutarimide unit.

The glutarimide resin is a thermoplastic resin having a substituted or unsubstituted imide group in the side chain. By having a substituted or unsubstituted imide group in the side chain, a desirable balance of properties can be expressed in terms of optical properties and heat resistance. (The glutarimide-based resin has at least the following general formula (501):

で表されるグルタルイミド単位（但し、式中、Ｒ³⁰¹、Ｒ³⁰²、Ｒ³⁰³は独立に水素または炭素数１〜１２個の非置換のまたは置換のアルキル基、シクロアルキル基、アリール基である。）を２０重量％以上有するグルタルイミド樹脂を含有することが好ましい。 General formula (501)

Wherein R ³⁰¹ , R ³⁰² and R ³⁰³ are independently hydrogen or an unsubstituted or substituted alkyl group having 1 to 12 carbon atoms, a cycloalkyl group or an aryl group. It is preferable to contain a glutarimide resin having 20% by weight or more.

As preferred glutarimide units constituting the glutarimide resin used in the present invention, R ³⁰¹ and R ³⁰² are hydrogen or a methyl group, and R ³⁰³ is a methyl group or a cyclohexyl group. The glutarimide unit may be a single type, or may include a plurality of types in which R ³⁰¹ , R ³⁰² , and R ³⁰³ are different.

  A preferred second structural unit constituting the glutarimide resin used in the present invention is a unit composed of an acrylate ester or a methacrylate ester. Preferable acrylic acid ester or methacrylic acid ester structural unit includes methyl acrylate, ethyl acrylate, methyl methacrylate, methyl methacrylate and the like. Another preferred imidizable unit includes N-alkyl methacrylamide such as N-methyl methacrylamide and N-ethyl methacrylamide. These second structural units may be of a single type or may include a plurality of types.

  The content of the glutarimide unit represented by the general formula (501) in the glutarimide resin is 20% by weight or more based on the total repeating unit of the glutarimide resin. The preferred content of the glutarimide unit is 20 to 95% by weight, more preferably 50 to 90% by weight, and still more preferably 60 to 80% by weight. When a glutarimide unit is smaller than this range, the heat resistance of the film obtained may be insufficient or transparency may be impaired. On the other hand, if it exceeds this range, the heat resistance is unnecessarily increased and it becomes difficult to form a film, the mechanical strength of the resulting film becomes extremely brittle, and the transparency may be impaired.

  The glutarimide-based resin may be further copolymerized with a third structural unit as necessary. Preferred examples of the third structural unit include styrene monomers such as styrene, substituted styrene and α-methylstyrene, acrylic monomers such as butyl acrylate, and nitrile monomers such as acrylonitrile and methacrylonitrile. , A structural unit obtained by copolymerizing maleimide monomers such as maleimide, N-methylmaleimide, N-phenylmaleimide, and N-cyclohexylmaleimide can be used. These may be directly copolymerized with the glutarimide unit and the imidizable unit in the glutarimide resin, and graft copolymerized with the resin having the glutarimide unit and the imidizable unit. It may be polymerized. When the third component is added, the content in the glutarimide resin is preferably 5 mol% or more and 30 mol% or less based on the total repeating units in the glutarimide resin.

  The glutarimide resin is described in US Pat. No. 3,284,425, US Pat. No. 4,246,374, JP-A-2-153904, and the like, and is obtained by using methyl methacrylate as a main raw material as a resin having an imidizable unit. It can be obtained by using a resin and imidizing the resin having an imidizable unit with ammonia or a substituted amine. When obtaining a glutarimide resin, a unit composed of acrylic acid, methacrylic acid, or an anhydride thereof may be introduced into the glutarimide resin as a reaction by-product. The presence of such a structural unit, particularly an acid anhydride, is not preferable because it reduces the total light transmittance and haze of the obtained film of the present invention. The acrylic acid or methacrylic acid content is 0.5 milliequivalent or less per gram of resin, preferably 0.3 milliequivalent or less, more preferably 0.1 milliequivalent or less. In addition, as seen in JP-A No. 02-153904, it is also possible to obtain a glutarimide resin by imidization using a resin mainly composed of N-methylacrylamide and methacrylic acid methyl ester.

The glutarimide resin preferably has a weight average molecular weight of 1 × 10 ⁴ to 5 × 10 ⁵ .

<Film having a low moisture permeability layer>
A film having a low moisture permeability layer provided on the second polarizing plate protective film to further reduce the moisture permeability can also be used. The film having the low moisture permeability layer may be formed of any material as long as the moisture permeability satisfies 100 g / m ² · 24 hr or less. A layer formed from a composition containing a compound having an aliphatic hydrocarbon group and an unsaturated double bond, or a layer having a resin containing a repeating unit derived from a chlorine-containing vinyl monomer is preferred. More preferably, the layer is formed from a composition containing a compound having a cyclic aliphatic hydrocarbon group and an unsaturated double bond in the molecule.
(Composition of low moisture permeable layer)
The low moisture-permeable layer that can be used for the second polarizing plate protective film is a layer formed from a composition containing a compound having a cyclic aliphatic hydrocarbon group and an unsaturated double bond in the molecule, or chlorine. The layer preferably has a resin containing a repeating unit derived from a vinyl monomer, and is formed from a composition containing a compound having a cyclic aliphatic hydrocarbon group and an unsaturated double bond in the molecule. More preferably, it is a layer.

  A layer formed from a composition containing as a main component a compound having a cyclic aliphatic hydrocarbon group and an unsaturated double bond group in the molecule will be described.

<< Layer formed from a composition mainly composed of a compound having a cycloaliphatic hydrocarbon group and an unsaturated double bond group in the molecule >>
In the present invention, the layer formed from the composition containing as a main component a compound having a cyclic aliphatic hydrocarbon group and an unsaturated double bond group in the molecule is a cyclic aliphatic group for imparting low moisture permeability. Contains a compound having a hydrocarbon group and an unsaturated double bond group in the molecule, and further contains a polymerization initiator, a translucent particle, a fluorine-containing or silicone compound, and a solvent as necessary. The composition can be formed by coating, drying and curing directly on the support or through another layer. Each component will be described below. In addition, the main component of a composition or a layer means the component which occupies 50 mass% or more of the composition or the layer.

[Compound having a cyclic aliphatic hydrocarbon group and an unsaturated double bond group in the molecule]
A compound having a cyclic aliphatic hydrocarbon group and an unsaturated double bond group in the molecule functions as a binder. In addition, a compound having a cycloaliphatic hydrocarbon group and an unsaturated double bond group can function as a curing agent, and can improve the strength and scratch resistance of the coating film, while at the same time being low. Moisture permeability can be imparted.
By using such a compound, low moisture permeability and high film strength can be realized. Although the details are not clear, by using a compound having a cycloaliphatic hydrocarbon group in the molecule, a hydrophobic cycloaliphatic hydrocarbon group is introduced into the low moisture-permeable layer, and is hydrophobized. Prevents uptake of molecules and reduces moisture permeability. Moreover, by having an unsaturated double bond group in a molecule | numerator, a crosslinking point density is raised and the diffusion path | route of the water molecule in a low moisture-permeable layer is restrict | limited. Increasing the crosslink point density also has the effect of relatively increasing the density of the cyclic aliphatic hydrocarbon group, making the inside of the low moisture permeable layer more hydrophobic, preventing the adsorption of water molecules, and reducing the moisture permeability. it is conceivable that.
In order to increase the crosslinking point density, the number of unsaturated double bond groups in the molecule is more preferably 2 or more.

The cyclic aliphatic hydrocarbon group is preferably a group derived from an alicyclic compound having 7 or more carbon atoms, more preferably a group derived from an alicyclic compound having 10 or more carbon atoms, and further preferably Is a group derived from an alicyclic compound having 12 or more carbon atoms.
The cycloaliphatic hydrocarbon group is particularly preferably a group derived from a polycyclic compound such as bicyclic or tricyclic.
More preferably, the central skeleton of the compound described in the claims of JP-A No. 2006-215096, the central skeleton of the compound described in JP-A No. 2001-10999, or the skeleton of an adamantane derivative may be used.

  As the cyclic aliphatic hydrocarbon group (including a linking group), a group represented by any one of the following general formulas (IY) to (VY) is preferable, and the following general formula (IY), (IIY), or (IVY) The group represented by general formula (IY) is more preferable.

Formula (IY)

  In general formula (IY), L and L ′ each independently represent a divalent or higher linking group. n represents an integer of 1 to 3. )

Formula (IIY)

  In general formula (IIY), L and L ′ each independently represent a divalent or higher linking group. n represents an integer of 1 to 2.

Formula (IIIY)

  In general formula (IIIY), L and L ′ each independently represent a divalent or higher linking group. n represents an integer of 1 to 2.

Formula (IVY)

  In general formula (IVY), L and L ′ each independently represent a divalent or higher valent linking group, and L ″ represents a hydrogen atom or a divalent or higher valent linking group.

General formula (VY)

  In general formula (V), L and L ′ each independently represent a divalent or higher linking group.

  Specific examples of the cyclic aliphatic hydrocarbon group include norbornyl, tricyclodecanyl, tetracyclododecanyl, pentacyclopentadecanyl, adamantyl, diamantanyl and the like.

Examples of the unsaturated double bond group include polymerizable functional groups such as a (meth) acryloyl group, a vinyl group, a styryl group, and an allyl group. Among them, a (meth) acryloyl group and —C (O) OCH═CH ₂ Is preferred. Particularly preferably, a compound containing three or more (meth) acryloyl groups in one molecule described below can be used.

A compound having a cycloaliphatic hydrocarbon group and having 3 or more unsaturated double bond groups in the molecule has the above-described cycloaliphatic hydrocarbon group and the group having an unsaturated double bond as a linking group. It is comprised by connecting via.
As the linking group, a single bond, an alkylene group having 1 to 6 carbon atoms which may be substituted, an amide group which may be substituted at the N-position, a carbamoyl group which may be substituted at the N-position, or an ester group , An oxycarbonyl group, an ether group, and the like, and groups obtained by combining these.

These compounds include, for example, polyols such as diols and triols having the above cyclic aliphatic hydrocarbon groups, and carboxylic acids and carboxylic acid derivatives of compounds having (meth) acryloyl groups, vinyl groups, styryl groups, allyl groups, etc. It can be easily synthesized by a one-step or two-step reaction with an epoxy derivative, an isocyanate derivative or the like.
Preferably, compounds such as (meth) acrylic acid, (meth) acryloyl chloride, (meth) acrylic anhydride, glycidyl (meth) acrylate, and compounds described in WO2012 / 00316A (eg, 1,1-bis ( (Acryloxymethyl) ethyl isocyanate) can be synthesized by reacting with a polyol having the above cyclic aliphatic hydrocarbon group.

  Preferred specific examples of the compound having a cyclic aliphatic hydrocarbon group and an unsaturated double bond group are shown below, but the present invention is not limited thereto.

(Polymerization initiator)
The composition containing as a main component a compound having a cyclic aliphatic hydrocarbon group and an unsaturated double bond group in the molecule preferably contains a polymerization initiator, but a photopolymerization initiator is preferred as the polymerization initiator. .
As photopolymerization initiators, acetophenones, benzoins, benzophenones, phosphine oxides, ketals, anthraquinones, thioxanthones, azo compounds, peroxides, 2,3-dialkyldione compounds, disulfide compounds, Examples include fluoroamine compounds, aromatic sulfoniums, lophine dimers, onium salts, borate salts, active esters, active halogens, inorganic complexes, and coumarins. Specific examples, preferred embodiments, commercially available products, and the like of the photopolymerization initiator are described in paragraphs [0133] to [0151] of JP-A-2009-098658, and can be suitably used in the present invention as well. it can.

  “Latest UV Curing Technology” {Technical Information Association, Inc.} (1991), p. 159, and “UV Curing System” written by Kiyomi Kato (published by the General Technology Center in 1989), p. Various examples are also described in 65-148 and are useful in the present invention.

  Commercially available photocleavable photoradical polymerization initiators include “Irgacure 651”, “Irgacure 184”, “Irgacure 819”, “Irgacure 907”, “Irgacure 1870” (CGI) manufactured by Ciba Specialty Chemicals Co., Ltd. -403 / Irgacure 184 = 7/3 mixing initiator), "Irgacure 500", "Irgacure 369", "Irgacure 1173", "Irgacure 2959", "Irgacure 4265", "Irgacure 4263", "Irgacure 127", " OXE01 ”, etc .;“ Kayacure DETX-S ”,“ Kayacure BP-100 ”,“ Kayacure BDK ”,“ Kayacure CTX ”,“ Kayacure BMS ”,“ Kayacure 2-EAQ ”,“ Cayacure ”manufactured by Nippon Kayaku Co., Ltd. "ABQ", " “Yacure CPTX”, “Kayacure EPD”, “Kayacure ITX”, “Kayacure QTX”, “Kayacure BTC”, “Kayacure MCA”, etc .; , KIP150, TZT) ", etc., and combinations thereof are preferred examples.

  The content of the photopolymerization initiator in the composition containing as a main component a compound having a cycloaliphatic hydrocarbon group and an unsaturated double bond group in the molecule used in the present invention is the polymerizable content contained in the composition. 0.5-8 mass% is preferable with respect to the total solid content in the composition for hard-coat layer formation from the reason that it sets so that a starting compound may be superposed | polymerized and a starting point may not increase too much, 1-5 The mass% is more preferable.

〔solvent〕
The composition containing as a main component a compound having a cyclic aliphatic hydrocarbon group and an unsaturated double bond group in the molecule used in the present invention can contain a solvent. As the solvent, various solvents can be used in consideration of the solubility of the monomer, the drying property during coating, the dispersibility of the translucent particles, and the like. Examples of such organic solvents include dibutyl ether, dimethoxyethane, diethoxyethane, propylene oxide, 1,4-dioxane, 1,3-dioxolane, 1,3,5-trioxane, tetrahydrofuran, anisole, phenetole, dimethyl carbonate, carbonic acid. Methyl ethyl, diethyl carbonate, acetone, methyl ethyl ketone (MEK), diethyl ketone, dipropyl ketone, diisobutyl ketone, cyclopentanone, cyclohexanone, methylcyclohexanone, ethyl formate, propyl formate, pentyl formate, methyl acetate, ethyl acetate, propyl acetate, Methyl propionate, ethyl propionate, γ-ptyrolactone, methyl 2-methoxyacetate, methyl 2-ethoxyacetate, ethyl 2-ethoxyacetate, ethyl 2-ethoxypropionate, 2-metho Siethanol, 2-propoxyethanol, 2-butoxyethanol, 1,2-diacetoxyacetone, acetylacetone, diacetone alcohol, methyl acetoacetate, methyl acetoacetate and other methyl alcohol, ethyl alcohol, isopropyl alcohol, n-butyl alcohol, cyclohexyl Alcohol, isobutyl acetate, methyl isobutyl ketone (MIBK), 2-octanone, 2-pentanone, 2-hexanone, ethylene glycol ethyl ether, ethylene glycol isopropyl ether, ethylene glycol butyl ether, propylene glycol methyl ether, ethyl carbitol, butyl carbitol , Hexane, heptane, octane, cyclohexane, methylcyclohexane, ethylcyclohexane, benzene, tolu Examples thereof include ene and xylene, and these can be used alone or in combination of two or more.

  When the base film is a cellulose acylate film, it is preferable to use at least one of dimethyl carbonate, methyl acetate, ethyl acetate, methyl ethyl ketone, acetylacetone, and acetone, more preferably dimethyl carbonate or methyl acetate, Methyl is particularly preferred.

  A solvent is used so that the solid content concentration of the composition mainly composed of a compound having a cycloaliphatic hydrocarbon group and an unsaturated double bond group in the molecule is 20-80% by mass. It is preferably used, more preferably 30 to 75% by mass, and still more preferably 40 to 70% by mass.

On the other hand, for the layer having a resin containing a repeating unit derived from the chlorine-containing vinyl monomer, the coating layer described in JP-A-2008-230036 [0042] to [0058] can be preferably used. As a component for forming a layer formed of a composition containing vinylidene chloride as a main component, Asahi Kasei Co., Ltd. among the coating layer materials described in JP-A-2008-230036 [0042] to [0058]. It is preferable to use “Saran Resin R204” manufactured by Life & Living Co., Ltd.
In addition, the main component of a composition or a layer means the component which occupies 50 mass% or more of the composition or the layer.

(Configuration of low moisture permeable layer, manufacturing method)
The low moisture-permeable layer may be a single layer or a plurality of layers. The method for laminating the low moisture permeable layer is not particularly limited, but the low moisture permeable layer is formed as a co-cast with the base film, or the low moisture permeable layer is laminated on the base film by coating. The low moisture-permeable layer is preferably provided by being laminated on the base film by coating. That is, it is more preferable that the second polarizing plate protective film is formed by laminating the low moisture permeable layer on the base film.

(Thickness of low moisture permeable layer)
The thickness of the low moisture permeable layer is preferably 1 to 20 μm, more preferably 2 to 18 μm, and particularly preferably 3 to 17 μm.

  It is also preferable that the low moisture permeable layer of the second polarizing plate protective film has a moisture permeable hard coat layer function, an antireflection function, an antifouling function and the like.

<Liquid crystal display device>
The liquid crystal display device of the present invention includes at least one polarizing plate of the present invention, and is arranged so that the first polarizing plate protective film is on the liquid crystal cell side. Since the liquid crystal display device of the present invention includes the polarizing plate of the present invention including the cellulose acylate film of the present invention, the contrast in the front direction and the color change in the viewing angle direction are remarkably improved.
In the liquid crystal display device of the present invention, the glass constituting the liquid crystal cell preferably has a thickness of 50 to 500 μm. By using such glass, the thickness of the liquid crystal display device can be reduced.
The liquid crystal display device of the present invention is a liquid crystal display device having a liquid crystal cell and a pair of polarizing plates disposed on both sides of the liquid crystal cell, wherein at least one of the polarizing plates is the polarizing plate of the present invention. An IPS, OCB or VA mode liquid crystal display device is preferable.
The specific configuration of the liquid crystal display device of the present invention is not particularly limited, and a known configuration can be adopted. For example, an example having the configuration shown in FIG. 1 can be adopted. Further, the configuration described in FIG. 2 of JP-A-2008-262161 can also be preferably employed.

  The present invention will be described more specifically with reference to the following examples. The materials, reagents, amounts and ratios of substances, operations, and the like shown in the following examples can be appropriately changed without departing from the gist of the present invention. Therefore, the scope of the present invention is not limited to the following specific examples.

(Preparation of cellulose acylate)
Cellulose acylates having different types of acyl groups and different degrees of substitution described in the following table were prepared. This was carried out by adding sulfuric acid (7.8 parts by mass with respect to 100 parts by mass of cellulose) as a catalyst, adding carboxylic acid as a raw material for the acyl substituent, and carrying out an acylation reaction at 40 ° C. At this time, the kind and substitution degree of the acyl group were adjusted by adjusting the kind and amount of the carboxylic acid. In addition, aging was performed at 40 ° C. after acylation. Further, the low molecular weight component of the cellulose acylate was removed by washing with acetone.

[Examples and Comparative Examples]
<Film formation of cellulose acylate film>
Using the cellulose acylate dope shown below, a film was formed by a solution casting method and used for each of Examples and Comparative Examples.

(Cellulose acylate dope A)
――――――――――――――――――――――――――――――――――――――
Cellulose acylate resin: Substituents described in the following table, those having a substitution degree 100 parts by mass Additives: those described in the following table
Dichloromethane 406 parts by mass Methanol 61 parts by mass ――――――――――――――――――――――――――――――――――――――

  The polycondensed ester was synthesized according to the description in JP-A No. 05-155809. That is, the dicarboxylic acid and diol described in the following table were used, and the ends were sealed with the groups described in the following table. Sugar ester was synthesize | combined according to description of WO2011 / 016279 and Unexamined-Japanese-Patent No. 2012-31313.

The structure of the discotic compound is described below.

  Cellulose acylate dope A has a matting agent (AEROSIL R972, manufactured by Nippon Aerosil Co., Ltd., secondary average particle size of 1.0 μm or less) as 0.13 parts by mass with respect to 100 parts by mass of cellulose acylate. The matting agent dispersion was mixed and stirred.

(Solution casting in a single layer)
The dope having the above composition was put into a mixing tank and stirred to dissolve each component, and then filtered through a filter paper having an average pore size of 34 μm and a sintered metal filter having an average pore size of 10 μm to prepare a cellulose acylate dope. The dope was cast with a band casting machine. The band was made of SUS. It peeled off from the band in the state whose residual solvent amount is 10-30 mass% more than the residual solvent amount before extending | stretching.
The film peeled off from the band was dried in the tenter device by using a tenter device that clips and conveys both ends of the web with a clip. At this time, the film peeled off from the band separately from the film subjected to the following stretching step was completely dried in an unstretched state to obtain a cellulose acylate film for a Tg measurement sample. It measured by the method as described in a specification, and described as film Tg in the following table | surface.
On the other hand, the drying time and temperature are adjusted so that the residual solvent amount at the start of stretching reaches the value described in the following table for the dried film, and the tenter during stretching is in an isothermal zone atmosphere. Stretching in the transverse direction (direction perpendicular to the conveying direction) at the draw ratio shown in the following table while applying hot air so that the temperature becomes the temperature shown in the table with respect to the Tg in the dry film of each film It was. In addition, it was confirmed that the solvent remained in the stretched film.
Thereafter, the film was transferred from tenter conveyance to roll conveyance, and further dried at 120 ° C. and wound up. The film thickness at this time is shown in the following table.

[Evaluation]
(Measurement of retardation value)
The produced cellulose acylate film was conditioned for 2 hours or more at 25 ° C. and a relative humidity of 60%, and was measured at 25 ° C. and a relative humidity of 60% using a birefringence measuring device (KOBRA 21ADH, manufactured by Oji Scientific Instruments). The Re value and the Rth value at a wavelength of 590 nm were measured and shown in the table below. Also, the value of Rth (nm) / film thickness (μm) was calculated and shown together in the table. The film thickness d was an average film thickness.

(Water contact test)
The produced film was cut into 4 cm squares, conditioned for 1 hour in an environment of 25 ° C. and 60% relative humidity, and then bonded to 5 cm square glass using an adhesive. In this state, Re and Rth of the film in the initial state were measured using KOBRA 21ADH (manufactured by Oji Scientific Instruments). Use a micropipette to drop 500 μl of pure water onto the measured film, immediately cover the film with Saran Wrap (registered trademark) (manufactured by Asahi Kasei Co., Ltd.), and paste the periphery with Kapton tape (manufactured by Nitto Denko Corporation) Sealed. The sample was placed in a thermostatic chamber adjusted to 35 ° C. for 12 hours and then taken out. The saran wrap was removed, and water on the film surface was wiped off. Then, after adjusting the humidity for 2 hours in an environment of 25 ° C. and 60% relative humidity, Re and Rth were measured. The absolute value of the difference between Re and Rth before and after the treatment was taken as the optical change during the water treatment test.

(Internal haze)
The internal haze is measured by dropping several drops of glycerin on both sides of the cellulose acylate film sample 40 mm × 80 mm of the present invention, and two glass plates (MICRO SLIDE GLASS part number S9213, manufactured by MATSUNAMI) from both sides. In a sandwiched state, glycerin was added between two glasses from a haze value measured according to JIS K-6714 using a haze meter “HGM-2DP” {manufactured by Suga Test Instruments Co., Ltd.] at 25 ° C. and a relative humidity of 60%. The value (%) obtained by subtracting the haze measured in a state where several drops were dropped was defined as the internal haze. The results are shown in the following table.

(Preparation of polarizing plate)
A polarizer was produced by adsorbing iodine to a stretched polyvinyl alcohol film. The thickness of the polarizer was prepared by changing the film thickness and the draw ratio of the unstretched polyvinyl alcohol film.

Then, according to the following steps, the cellulose acylate films of Examples and Comparative Examples were bonded to one surface of the polarizer, and the second polarizing plate protective film described in the following table was bonded to the other surface. .
Step 1: It was immersed in a 1.5 mol / L sodium hydroxide solution at 55 ° C. for 120 seconds and then washed with water. Furthermore, after being immersed for 1 minute in said 0.005 mol / L dilute sulfuric acid aqueous solution, it was immersed in water and the dilute sulfuric acid aqueous solution was fully washed away. Finally, the sample was thoroughly dried at 120 ° C. It dried and the cellulose acetate film which saponified the side bonded with a polarizer was obtained.
Process 2: The said polarizer was immersed in the polyvinyl alcohol adhesive tank of 2 mass% of solid content for 1-2 seconds.
Step 3: Excess adhesive adhered to the polarizer in Step 2 was lightly wiped off, and this was placed on the cellulose ester film treated in Step 1.
Step 4: Step 3 Cellulose ester film laminated with the polarizer and the pressure backside cellulose ester film 20-30 N / cm ^2, the conveyance speed was pasted at approximately 2m / min.
Process 5: The sample which bonded the polarizer produced in process 4 and the cellulose-ester film in the dryer of 80 degreeC was dried for 2 minutes, and the polarizing plate corresponding to a cellulose-ester film was produced, respectively.
It arrange | positioned so that the transmission axis of a polarizer and the slow axis of the cellulose acylate film of each Example and comparative example which performed the saponification process above may become parallel.

  Films other than the cellulose acylate film as the second polarizing plate protective film described in the following table were bonded to the polarizer as follows. On the film, the following UV curable adhesive was coated with an adhesive using a micro gravure coater (gravure roll: # 300, rotational speed 140% / line speed) to a thickness of 5 μm. Then, this was bonded together with the cellulose ester film with the roll machine to the polarizer immersed in the said polyvinyl alcohol adhesive agent. Electron beams were irradiated from both sides of the bonded film to obtain a polarizing plate having films on both sides of the polarizer. The line speed was 20 m / min, the acceleration voltage was 250 kV, and the irradiation dose was 20 kGy.

<UV curing adhesive>
A UV curable adhesive was prepared by blending 100 parts by mass of 2-hydroxyethyl acrylate and 11 parts by mass of ditrimethylolpropane tetraacrylate (manufactured by Sartomer Japan, trade name SR355).

［上記一般式中、Ｒ¹は水素原子、Ｒ²およびＲ³はメチル基であるラクトン環構造を有する（メタ）アクリル系樹脂｛共重合モノマー質量比＝メタクリル酸メチル／２−（ヒドロキシメチル）アクリル酸メチル＝８／２、ラクトン環化率約１００％、ラクトン環構造の含有割合１９．４％、質量平均分子量１３３０００、メルトフローレート６．５ｇ／１０分（２４０℃、１０ｋｇｆ）、Ｔｇ１３１℃｝９０質量部と、アクリロニトリル−スチレン（ＡＳ）樹脂｛トーヨーＡＳ ＡＳ２０、東洋スチレン社製｝１０質量部との混合物；Ｔｇ１２７℃］ <Second polarizing plate protective film (film other than cellulose acylate film)>
COP: cycloolefin film (film thickness 25μm)
PET: Polyethylene terephthalate film (film thickness 25 μm)
PC: Polycarbonate film (film thickness 25μm)
PMMA1: (meth) acrylic resin film having a lactone ring structure having the following structure (film thickness: 25 μm)

[(Meth) acrylic resin having a lactone ring structure in which R ¹ is a hydrogen atom, and R ² and R ³ are methyl groups in the above general formula {copolymerization monomer mass ratio = methyl methacrylate / 2- (hydroxymethyl) Methyl acrylate = 8/2, lactone cyclization rate about 100%, lactone ring structure content 19.4%, mass average molecular weight 133000, melt flow rate 6.5 g / 10 min (240 ° C., 10 kgf), Tg 131 ° C. } A mixture of 90 parts by mass and 10 parts by mass of acrylonitrile-styrene (AS) resin {Toyo AS AS20, manufactured by Toyo Styrene Co., Ltd .; Tg 127 ° C.]

PMMA2: The following low moisture-permeable layer (2 μm) coated on PMMA1 (film thickness 23 μm) (film thickness 25 μm)
[Preparation of composition for forming a low moisture-permeable layer]
Chlorine-containing polymer: R204
{"Saran Resin R204" manufactured by Asahi Kasei Life & Living Co., Ltd.} 12.0g
・ Tetrahydrofuran 62.0g
・ Toluene 13.0g
・ Methyl ethyl ketone 13.0g
[Formation of a low moisture-permeable layer]
A PMMA1 film (23 μm) is drawn out in the form of a roll as a transparent protective film, and the above composition for forming a low moisture permeable layer is applied using a bar coater under a film transport speed of 30 m / min. The film was dried for a while, and while being transported, the film was wound after passing through a zone having an atmosphere of 25 ° C. and 65% for 1 minute. At this time, the thickness of the low moisture-permeable layer was 2.0 μm.

(Moisture permeability)
The moisture permeability of the film used as the second polarizing plate protective film was measured by the method defined in JISZ0208 (40 ° C. 90% RH 24 h).

(Mounting on liquid crystal display devices)
The front and back polarizing plates and retardation plates of a VA mode liquid crystal TV (LC-46LX1, manufactured by SHARP) were peeled off and used as a liquid crystal cell. As the viewing-side polarizing plate and the backlight-side polarizing plate of the liquid crystal display device using the vertical alignment type liquid crystal cell, the polarizing plates of the respective examples and comparative examples were installed. At this time, the polarizing plate was installed so that the 1st polarizing plate protective film (The cellulose acylate film of Examples 1-25 and Comparative Examples 1-7) might become a liquid crystal cell side. The viewing side polarizing plate and the backlight side polarizing plate were attached to the liquid crystal cell via an adhesive. The crossed Nicols were arranged so that the transmission axis of the viewing side polarizing plate was in the vertical direction and the transmission axis of the backlight side polarizing plate was in the left and right direction.
The produced liquid crystal display device was used as the liquid crystal display device of each example and comparative example.

(Condensation unevenness of liquid crystal display device)
With the liquid crystal panel mounted with the prepared polarizing plate laid sideways, 500 μl of pure water was dropped on the viewing side polarizing plate surface using a micropipette, and the film was immediately covered with Saran Wrap (Asahi Kasei Co., Ltd.). Was sealed with Kapton tape (manufactured by Nitto Denko). In this state, the panel was turned on and allowed to stand for 12 hours. Thereafter, the Saran wrap was removed, the water on the film surface was wiped off, and after lighting for 3 hours, the panel was observed from an oblique direction to observe the presence or absence of unevenness. A and B are practical levels.
A: There is a slight difference in light leakage between the water contact portion and the surrounding area B: There is a difference in light leakage between the water contact portion and the surrounding area, but the boundary is unclear C: Light leakage between the water contacting portion and the surrounding area There is a difference, the boundary is clear and the water contact mark is conspicuous

(Evaluation of unevenness in four corners of liquid crystal display devices)
The prepared liquid crystal panel mounted with the polarizing plate was placed in an environment of 40 ° C. and 95% relative humidity for 24 hours, then placed in a 40 ° C. dry environment for 2 hours, and then lit for 24 hours in an environment of 25 ° C. and 60% relative humidity. Later, unevenness was observed from the front of the panel. A and B are practical levels.
A: There is no light leakage at the four corners of the panel or light leakage is very weak. B: Light leakage is observed at the four corners of the panel, but the boundary is unclear and light leakage is not noticeable. C: Light leakage is observed at the four corners of the panel. The clear and light leaking part and the part that is not so clearly visible.

(Front contrast evaluation)
Using a measuring instrument (BM5A, manufactured by TOPCON), the luminance values of black display and white display in the front direction of the panel were measured in a dark room, and the front contrast (white luminance / black luminance) was calculated. A and B are practical levels.
The observed contrast was evaluated according to the following criteria.
A: Contrast is 6000 or more B: Contrast is 5700 or more and less than 6000 C: Contrast is less than 5700

(Curl evaluation of polarizing plate)
The produced polarizing plate is cut into a size of 10 cm × 10 cm, placed in a temperature / humidity environment of 25 ° C. and a relative humidity of 60% for 48 hours or more, and then separated most from the plane when the polarizing plate is left on a flat surface. The distance to the place was taken as the curl amount.
A: The curl amount is less than ± 10 mm.
B: The curl amount is ± 10 mm or more and less than ± 20 mm.
C: Curling amount is ± 20 mm or more

22 Protective film 12 Viewing side polarizer 15 Retardation film 13 Liquid crystal layer 14 Retardation film 11 Backlight side polarizer 21 Protective film

Claims (12)

A cellulose acylate film containing a cellulose acylate having a total acyl group substitution degree of 2.1 to 2.6 and satisfying the following (1) to (4);
(1) It contains at least one polycondensation ester containing an aromatic dicarboxylic acid residue and an aliphatic diol residue, and the ratio of the aromatic dicarboxylic acid residue to all the dicarboxylic acid residues in the polycondensation ester is 70. Mol% or more;
(2) The film thickness is 15 to 45 μm;
(3) Retardation (Rth) in the film thickness direction at a wavelength of 550 nm satisfies Rth / d ≧ 0.0025 (where d indicates film thickness (nm));
(4) The absolute value of Rth change during the water contact test is 5 nm or less;
Here, the absolute value of the Rth change during the water contact test is taken out after the film is immersed in water heated to 40 ° C. for 12 hours, and then water droplets on the surface of the film are wiped off and air-dried, followed by 25 ° C. and 60% relative humidity environment. It is the absolute value of the Rth difference between the Rth at a wavelength of 590 nm and the untreated state after being left for 24 hours.   The cellulose acylate film according to claim 1, wherein an internal haze of the cellulose acylate film is 0.05% or less.   The cellulose acylate film according to claim 1 or 2, wherein the cellulose acylate is cellulose acetate.   The cellulose acylate film is formed by stretching at a stretching temperature of Tg-70 ° C. to Tg-30 ° C. (Tg is a glass transition temperature of cellulose acylate) with a residual solvent amount of 35 to 65% by mass. Item 4. The cellulose acylate film according to any one of Items 1 to 3.   It contains a first polarizing plate protective film and a second polarizing plate protective film, and the first polarizing plate protective film is the cellulose acylate film according to any one of claims 1 to 4. A characteristic polarizing plate.   The polarizing plate according to claim 5, wherein the second polarizing plate protective film has a thickness of 10 to 29 μm. The polarizing plate according to claim 5 or 6, wherein a moisture permeability of the second polarizing plate protective film is 100 g / m ² · 24 hr or less.   A liquid crystal display device comprising the polarizing plate according to claim 5.   The liquid crystal display device according to claim 8, wherein the first polarizing plate protective film is disposed on the liquid crystal cell side.   The liquid crystal display device according to claim 8, wherein the first polarizing plate protective film is disposed so as to be on a liquid crystal cell side and has a glass having a thickness of 50 to 500 μm. Stretching the cellulose acylate film at a stretching temperature of Tg-70 ° C. to Tg-30 ° C. (Tg is a glass transition temperature of cellulose acylate) with a residual solvent amount of 35 to 65% by mass, The method for producing a cellulose acylate film, wherein the cellulose acylate film contains a cellulose acylate having a total acyl group substitution degree of 2.1 to 2.6 and satisfies the following (1) and (2): ;
(1) It contains at least one polycondensed ester containing an aromatic dicarboxylic acid residue and an aliphatic diol residue, and the ratio of the aromatic dicarboxylic acid residue to all the dicarboxylic acid residues in the polycondensed ester is 70 mol% or more;
(2) The film thickness is 15 to 45 μm.   The method for producing a cellulose acylate film according to claim 11, wherein the cellulose acylate film is the cellulose acylate film according to claim 1.

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