KR20140042710A - Cellulose acylate film, polarizing plate, and liquid crystal display device - Google Patents

Abstract

The present invention provides a cellulose acylate film which maintains general display properties (high front surface contrast, optical leakage control toward a slope direction) when the cellulose acylate film is mounted on a liquid crystal display device, and is unlikely to generated display unevenness due to dew condensation. The cellulose acylate film has the film thickness of 20-60 μm, contains cellulose acylate and an additive with the total acyl substitution degree of 2.0-2.55, and satisfies the following formulas (I)-(IV): (I)30 nm <= Re (590) <= 90 nm; (II) 100 nm <= Rth (590) <= 150 nm; (III) 2.0 <= Rth (590)/d <= 5.0; and (IV) internal haze <= 0.05 %; and (V) ΔM <= 1.0%.

Description

Cellulose acylate film, polarizer and liquid crystal display device {CELLULOSE ACYLATE FILM, POLARIZING PLATE, AND LIQUID CRYSTAL DISPLAY DEVICE}

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, it is related with the cellulose acylate film which can be used suitably as optical films, such as a polarizing plate protective film and retardation film.

Background Art In recent years, TV applications of liquid crystal display devices have progressed, and high quality and low price associated with larger screen sizes have been increasingly demanded. In particular, the liquid crystal display of VA mode has become the most common as a liquid crystal display for TV because of its relatively high contrast and relatively high production yield. Although a polarizing plate is attached to such a liquid crystal display device, the cellulose acylate film is employ | adopted as a protective film of such a polarizing plate (Unexamined-Japanese-Patent No. 2003-62899).

By the way, in recent years, the demand for thinning of a liquid crystal display device is increasing. Therefore, it is advantageous to make the polarizing plate, which is a component of the liquid crystal display, thinner.

As a method of thinning a polarizing plate, it is conceivable to thin the film (cellulose acylate film) which has a cellulose acylate used as a protective film of a polarizing plate as a main component. However, in such a thin film, there exists a concern that display nonuniformity by dew condensation will generate | occur | produce. The dew condensation nonuniformity is a nonuniformity which arises when water adheres normally to a film partly, and the part to which water adhered and the part which is not adhered generate | occur | produce. In particular, as a result of the present inventor's examination, when such a cellulose acylate film is attached to the thin liquid crystal display device whose glass of a panel is 500 micrometers or less as a liquid crystal display device, it turns out that display nonuniformity of a liquid crystal display device arises in a short time. there was.

An object of the present invention is to solve such problems, and is a thin cellulose acylate film, which, when attached to a liquid crystal display device, maintains general display characteristics (high front contrast, suppression of light leakage in an oblique direction). It is an object of the present invention to provide a cellulose acylate film in which display unevenness due to condensation does not easily occur.

Here, Unexamined-Japanese-Patent No. 2003-62899 considers raising Nz factor in the cellulose ester film with a high degree of substitution of an acyl group, and employ | adopts the method of extending | stretching in water as this means. However, as a result of the present inventor's examination, Japanese Unexamined Patent Publication No. 2003-62899 shows that a cellulose ester film having a high degree of substitution of acyl groups is drawn in water, and the obtained film has a slightly high haze. Moreover, in order to express a predetermined retardation (Rth) while thinning a film, it is necessary to make Rth / d (d is thickness of a film) high, but acyl substitution as described in Unexamined-Japanese-Patent No. 2003-62899. In high cellulose ester film, a film with high Rth / d cannot be manufactured.

In the present invention, by using a cellulose ester having a low degree of acyl group substitution and by water treatment after stretching, the desired retardation can be expressed even in a thin film, and the internal haze can be lowered, and the equilibrium moisture content change before and after dipping pure water It was able to make it small and found that the cellulose acylate film which is hard to become condensation nonuniform even if water adhered as a result was obtained.

Specifically, the problem was solved by the following means <1>, and preferably by <2> to <11>.

The cellulose acylate film whose film thickness is 20-60 micrometers, contains the cellulose acylate and additive of 2.0-2.55 total acyl substitution degree, and satisfy | fills following formula (I)-(IV).

Formula (I) 30 nm ≤ Re (590) ≤ 90 nm

Formula (II) 100 nm ≤ Rth (590) ≤ 150 nm

Equation (III) 2.0 ≤ Rth (590) / d ≤ 5.0

Equation (IV) Internal haze ≤ 0.05%

Formula (V) ΔM ≤ 1.0%

(Wherein Re (590) represents the retardation (nm) in the in-plane direction at the wavelength 590 nm, Rth (590) represents the retardation (nm) in the film thickness direction at the wavelength 590 nm, and d is ΔM is the equilibrium moisture content at 25 ° C. 80% by the Karl Fischer method after immersing the cellulose acylate film in 40 ° C. pure water for 24 hours, and 25 ° C. 80 by the Karl Fischer method before immersion. The difference in equilibrium moisture content in% is shown.)

<2> The cellulose acylate film of <1>, wherein the additive contains a compound containing an aromatic.

The cellulose acylate film as described in <2> containing at least 1 sort (s) chosen from a sugar ester compound, a nitrogen-containing ring compound, and ester type polymer as a compound containing <3> the aromatic.

<4> Film thickness is 30-50 micrometers, total acyl substitution degree is 2.4-2.55, Re (590) is 40-90 nm, Rth (590) is 110-130 nm, internal haze is 0.03% or less The cellulose acylate film in any one of <1>-<3> whose (DELTA) M is 0.5% or less.

The process of forming the polymer solution which has the cellulose acylate of <5> total substitution degree 2.0-2.55, a solvent, and an additive in the form of a film, and after extending | stretching the film, it controls so that a film thickness may be 20-60 micrometers, and extends | stretches A process for producing a cellulose acylate film, comprising the step of further treating the stretched film with water.

The process of <6> said water treatment is a process of immersing a cellulose acylate in 25-85 degreeC water for 5 second or more, and adjusting so that the film elongation rate of the conveyance direction at the time of the said water treatment may be 1% or less. The manufacturing method of the cellulose acylate film as described in <5> characterized by the above-mentioned.

<7> The manufacturing method of the cellulose acylate film as described in <5> or <6> whose said cellulose acylate film is a cellulose acylate film in any one of <1>-<4>.

The polarizing plate containing a <8> polarizer and the cellulose acylate film in any one of <1>-<4>.

<9> The said polarizing plate has a protective film also in the surface on the opposite side to the said cellulose acylate film, The protective film is a cellulose acylate film whose film thickness is 20-60 micrometers, The polarizing plate as described in <8> characterized by the above-mentioned.

<10> Liquid crystal display device which has a polarizing plate as described in <8> or <9>.

<11> The liquid crystal display device according to <10>, wherein the liquid crystal display device has a glass substrate having a thickness of 50 to 500 µm.

A cellulose acylate film having a thin thickness of cellulose acylate film, in which high front contrast is maintained and light leakage when viewed in the inclined direction is suppressed, and display irregularity due to condensation is less likely to occur when attached to a liquid crystal display device. Could provide.

1 is a schematic cross-sectional view of an example of a liquid crystal display of the present invention.

Hereinafter, the contents of the present invention will be described in detail. The description of constituent elements described below may be made based on a representative embodiment of the present invention, but the present invention is not limited to such embodiment. In the present specification, &quot; &quot; is used to mean that the numerical values described before and after the numerical value are included as a lower limit value and an upper limit value. In addition, in this specification, a "front side" means a display surface side, and a "rear side" means a backlight side. In addition, in this specification, "front" means the normal direction with respect to a display surface, and "front contrast (henceforth contrast is also called CR)" means the white luminance and black luminance measured in the normal direction of a display surface. Let's say the calculated contrast.

<Cellulose acylate film>

The cellulose acylate film of this invention is 20-60 micrometers in film thickness, contains the cellulose acylate and additive of 2.0-2.55 total acyl substitution degree, and satisfy | fills following formula (I)-(IV), It is characterized by the above-mentioned. do.

Formula (I) 30 nm ≤ Re (590) ≤ 90 nm

Formula (II) 100 nm ≤ Rth (590) ≤ 150 nm

Equation (III) 2.0 ≤ Rth (590) / d ≤ 5.0

Equation (IV) Internal haze ≤ 0.05%

Formula (V) ΔM ≤ 1.0%

(Wherein Re (590) represents the retardation (nm) in the in-plane direction at the wavelength 590 nm, Rth (590) represents the retardation (nm) in the film thickness direction at the wavelength 590 nm, and d is ΔM is the equilibrium moisture content at 25 ° C. 80% by the Karl Fischer method after immersing the cellulose acylate film in 40 ° C. pure water for 24 hours, and 25 ° C. 80 by the Karl Fischer method before immersion. The difference in equilibrium moisture content in% is shown.)

In the present invention, in the cellulose acylate film having a thin film thickness of 20 to 60 µm and satisfying the above formulas (I) to (III), a cellulose acylate having a predetermined total acyl substitution degree is used and The said subject is solved by making haze <0.05% and change (DELTA) M of equilibrium moisture content below 1.0%. Such means is achieved by, for example, water treatment.

This reason is not limited to any theory, but the following reasons can be considered.

When the cellulose acylate film is subjected to water treatment, the cellulose acylate film functions to swell during water treatment. Although water is removed when drying a cellulose acylate film, it is inferred that a part of the point where the water of the cellulose acylate film existed becomes a space | gap. Moreover, the equilibrium moisture content of a cellulose acylate film treated with water increases in a high humidity environment. For this reason, it is considered that water molecules easily enter the voids.

By the way, when water adheres to the cellulose acylate film which is not water-treated, the cellulose acylate film swells only at the point where the water adheres. Although it dehydrates with time or by drying, it is thought that the film density of the point where water was present falls and equilibrium moisture content rises. Even in the same environment, since the equilibrium moisture content is different at the point where the drop of water is dropped and the point at which the drop of water is not dropped, nonuniformity is visually recognized at the boundary portion.

On the other hand, once water adheres to the cellulose acylate film subjected to the water treatment, the point to which the water adheres is swollen with water. However, since the voids have already increased in the film, the equilibrium moisture content of the film does not change after dehydration. Therefore, it is inferred that the equilibrium moisture content difference does not arise at the point where the water of the film adhered and the point which is not adhered, and the display nonuniformity which causes the dew condensation nonuniformity does not arise.

<Cellulose Acylate>

The cellulose acylate film of this invention contains the cellulose acylate of the total acyl substitution degree 2.0-2.55.

Cellulose which is a raw material of the cellulose acylate used in the present invention includes cotton linter and wood pulp (softwood pulp, softwood pulp) and the like, and may be used even if the cellulose acylate obtained from any raw material cellulose is used. You may also For detailed descriptions of these raw celluloses, for example, Marusawa Udaz, "Plastic Materials Course (17) Fibrin-Based Resin", Daily Industrial Newspaper Company (Issued in 1970) or Invention Association Publication No. 2001-1745 ( Cellulose as described in pages 7 to 8) can be used, and the cellulose acylate laminated film of the present invention is not particularly limited.

First, it describes in detail about the cellulose acylate used preferably for this invention. The glucose unit which binds (beta) -1,4 which comprises cellulose has the hydroxyl group liberated in the 2nd, 3rd, and 6th positions. A cellulose acylate is a polymer (polymer) which acylated some or all of these hydroxyl groups by the acyl group. An acyl substitution degree means the sum total of the ratio (100% acylation in each position is substitution degree 1) in which the hydroxyl group of the cellulose located in 2nd, 3rd, and 6th positions is acylated.

Only one kind of acyl group may be used for the cellulose acylate of the present invention, or two or more kinds of acyl groups may be used.

The acyl group of the cellulose acylate in the present invention may be an aliphatic group or an allyl group, and is not particularly limited. They are alkylcarbonyl ester, alkenylcarbonyl ester, aromatic carbonyl ester, aromatic alkylcarbonyl ester, etc. of cellulose, for example, and may have group substituted further, respectively. Preferred examples thereof include an acetyl group, propionyl group, butanoyl group, heptanoyl group, hexanoyl group, octanoyl group, decanoyl group, dodecanoyl group, tridecanoyl group, tetradecanoyl group, hexadecanoyl group and octade And canoyl group, isobutanoyl group, tert-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, tert-butanoyl group, oleoyl group, benzoyl group, naphthylcarbonyl group, cinnamoyl group and the like are more preferable, and particularly preferred. Is an acetyl group, propionyl group, butanoyl group (when the acyl group has 2 to 4 carbon atoms), and more particularly preferably an acetyl group (when the cellulose acylate is cellulose acetate).

That is, triacetyl cellulose (TAC), diacetyl cellulose (DAC), cellulose acetate propionate (CAP), cellulose acetate butyrate (CAB), cellulose acetate phthalate, etc. are mentioned as said cellulose acylate. It is preferable that the cellulose acylate film of this invention is cellulose acetate from a viewpoint of retardation expression property and cost.

The film of this invention contains the cellulose acylate of the total substitution degree 2.0-2.55. It is preferable that total acyl substitution degree of the said cellulose acylate satisfies 2.4-2.55, and it is more preferable that it is 2.4-2.5.

In addition, substitution degree of an acyl group can be measured according to the method of the prescription | regulation to ASTM-D 817-96. The portion not substituted with an acyl group usually exists as a hydroxyl group.

In a preferred embodiment of the present invention, even in the case of a cellulose acylate film containing a cellulose acylate having a low acyl substitution degree, the improvement of the retardation change under wet heat conditions and the reverse wavelength dispersion of the wavelength dispersion (ΔRe is positive) Improvement can be improved simultaneously, and the cellulose acylate film containing the cellulose acylate with the low acyl substitution degree can be manufactured.

These cellulose acylate can be synthesize | combined by a well-known method, For example, it can synthesize | combine by the method of Unexamined-Japanese-Patent No. 10-45804.

In the acylation of cellulose, when an acid anhydride or an acid chloride is used as an acylating agent, an organic acid, for example, acetic acid, methylene chloride, etc. are used as an organic solvent which is a reaction solvent.

As the catalyst, when the acylating agent is an acid anhydride, a protic catalyst such as sulfuric acid is preferably used, and when the acylating agent is an acid chloride (for example, CH ₃ CH ₂ COCl), a basic compound is used.

The most common method for industrial synthesis of mixed fatty acid esters of cellulose is to acylate cellulose with mixed organic acid components containing fatty acids (acetic acid, propionic acid, valeric acid, etc.) corresponding to acetyl groups and other acyl groups or their acid anhydrides. .

It is preferable that it is 40000-200000 in number average molecular weight (Mn), and, as for the molecular weight of the said cellulose acylate, it is more preferable that it is 100000-200000. It is preferable that Mw / Mn ratio of the cellulose acylate used by this invention is 4.0 or less, More preferably, it is 1.4-2.3.

In the present invention, the average molecular weight and molecular weight distribution of cellulose acylate and the like calculate the number average molecular weight (Mn) and the weight average molecular weight (Mw) using gel permeation chromatography (GPC), and the international publication WO2008-. By the method described in 126535, the ratio can be calculated.

It is preferable that content of the said cellulose acylate in a film of the film of this invention is 85 mass% or more with respect to the mass of a film, It is more preferable to exceed 85 mass%, It is especially preferable that it is 86 mass% or more. Further, the higher the total acyl substitution degree of the cellulose acylate, the lower the cellulose acylate content in the film, and the lower the total acyl substitution degree, the higher the cellulose acylate content in the film.

<Additives>

The cellulose acylate film of this invention contains an additive, As an additive, the compound containing an aromatic is preferable. By employ | adopting a compound containing an aromatic, Re and Rth expressability of an additive are high and it is easy to thin film.

The additive is preferably selected from an ester polymer, a sugar ester compound, and a nitrogen-containing ring compound, and an ester-based polymer containing an aromatic, a sugar ester compound containing an aromatic, and a nitrogen-containing ring compound containing an aromatic are preferable. Do.

(Ester-based polymer)

In this invention, you may contain the ester type polymer as an additive. When such an ester polymer is blended, the retardation expression becomes high, and even if water penetrates into the film, it is difficult to move inside the film, so that the change in retardation before and after the water treatment can be reduced. Moreover, it is preferable that ester type polymer contains an aromatic.

In addition, both ends of the ester polymer used in the present invention are each independently a -OH group, -OC (= O) -R ¹ group, -C (= O) -OR ² group, -OR ³ group and- It is preferable that it is either selected from the group which consists of a COOH group (However, said R <^1> -R <^3> represents an aliphatic group each independently).

In this specification, the residue of an ester type polymer is a partial structure of an ester type polymer, and shows the partial structure which has the characteristic of the monomer which forms ester type polymer. For example, the dicarboxylic acid residue formed from dicarboxylic acid HOOC-R-COOH is -OC-R-CO- and the diol residue formed from diol HO-R'-OH is -O-R'-O - to be.

As the dicarboxylic acid residue, an aromatic dicarboxylic acid residue and an aliphatic dicarboxylic acid residue may be used for the ester polymer.

It is preferable that the said ester type polymer used for this invention contains at least 1 type of aromatic dicarboxylic acid residue.

Moreover, it is preferable that the ratio of the aromatic dicarboxylic acid residue with respect to all the dicarboxylic acid residues in the ester type polymer used for this invention is 50 mol% or more.

By making the said aromatic dicarboxylic acid residue ratio into 50 mol% or more, there exists a tendency for the cellulose acylate film which shows sufficient optical expressability (especially large value of Rth per film thickness) to be obtained even if it is thin.

In this specification, the said aromatic dicarboxylic acid residue means the dicarboxylic acid residue containing at least 1 arylene group. That is, in the present specification, in the aromatic dicarboxylic acid residue, in addition to the -OC-Ar-CO- residue, for example, -OC-Ar'-L-CO- or -OC-L'-Ar ' Dicarboxylic acid residues having a structure such as '-CO-, -OC-L' '-Ar' ''-L ''-CO- (Ar, Ar ', Ar' 'and Ar' '' Each independently represents an arylene group, and L, L 'and L' 'each independently represent a divalent linking group other than the arylene group). As a bivalent coupling group other than the said arylene group, an aliphatic group, an atomic coupling group, etc. are mentioned, for example, An alkylene group, an alkyleneoxy group, an oxygen atom, a sulfur atom, etc. are mentioned specifically ,.

Especially, it is preferable that the said aromatic dicarboxylic acid residue is a structure of -OC-Ar-CO- residue from a compatible viewpoint with a cellulose acylate.

It is preferable that said Ar is a C6-C16 arylene group, It is more preferable that it is a C6-C12 arylene group, It is especially preferable that it is a phenylene group or a naphthylene group, It is especially preferable that it is a phenylene group. Moreover, although said Ar may or may not have a substituent further, it is preferable that it does not have a substituent, As a substituent, a hydroxyl group, an acyl group, a carbonyl group, etc. are mentioned, for example.

Specific examples of the aromatic dicarboxylic acid residues include phthalic acid residues, terephthalic acid residues, isophthalic acid residues, 1,5-naphthalenedicarboxylic acid residues, 1,4-naphthalenedicarboxylic acid residues, and 1,8-naphthalene. Dicarboxylic acid residues, 2,8-naphthalenedicarboxylic acid residues, 2,6-naphthalenedicarboxylic acid residues, and the like. Among these examples, phthalic acid residues, terephthalic acid residues, 2,6-naphthalenedicarboxylic acid residues are preferable, phthalic acid residues and terephthalic acid residues are more preferable, and terephthalic acid residues are more preferable.

An aromatic dicarboxylic acid residue is formed in the said ester polymer by the aromatic dicarboxylic acid used for mixing.

When the said ester polymer contains a terephthalic acid residue as an aromatic dicarboxylic acid residue, it is excellent in compatibility with a cellulose acylate, and bleeding-out occurs also at the time of film forming and heat drawing of a cellulose acylate film. It can be set as the cellulose acylate film which does not.

Moreover, in the said ester polymer, only 1 type of aromatic dicarboxylic acid residue may be contained and may be contained 2 or more types. When two aromatic dicarboxylic acid residues are contained in the said ester polymer, it is preferable that a phthalic acid residue and a terephthalic acid residue are contained.

The ester polymer may contain an aliphatic dicarboxylic acid residue in addition to the aromatic dicarboxylic acid residue as a dicarboxylic acid residue.

Specific examples of the aliphatic dicarboxylic acid residues include, for example, oxalic acid residues, malonic acid residues, succinic acid residues, maleic acid residues, fumaric acid residues, glutaric acid residues, adipic acid residues, pimeric acid residues, Suberic acid residues, azelaic acid residues, sebacic acid residues, dodecanedicarboxylic acid residues, 1,4-cyclohexanedicarboxylic acid residues, and the like.

In the said ester polymer, an aliphatic dicarboxylic acid residue is formed from the aliphatic dicarboxylic acid used for mixing.

It is preferable that average carbon number is 5.5-10.0, as for the said aliphatic dicarboxylic acid residue, it is more preferable that it is 5.5-8.0, It is still more preferable that it is 5.5-7.0. When the average carbon number of the aliphatic diol is 7.0 or less, it is possible to reduce the heating loss of the compound and to prevent the occurrence of a planar failure caused by process contamination due to bleed out during drying of the cellulose acylate web. Moreover, when the average carbon number of aliphatic diol is 2.5 or more, it is excellent in compatibility, and precipitation of an ester polymer does not occur easily, and it is preferable.

Specifically, when the said polymeric ester contains the said aliphatic dicarboxylic acid residue, it is preferable to contain a succinic acid residue or adipic acid residue, and it is more preferable to have a succinic acid residue.

In the said ester polymer, only 1 type of aliphatic dicarboxylic acid residue may be contained and 2 or more types may be contained. When two types of aliphatic dicarboxylic acid residues are contained in the said ester polymer, it is preferable that the succinic acid residue and the adipic acid residue are contained. When one type of aliphatic dicarboxylic acid residue is contained in the said ester polymer, it is preferable that 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.

As the diol moiety, an aromatic diol moiety and an aliphatic diol moiety can be used for the ester polymer.

The ester polymer used in the present invention contains at least one aliphatic diol residue as the diol residue.

Examples of the aliphatic diols used in the present invention include alkyldiols and alicyclic diols, and examples thereof include 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 (neopentylglycol), 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, and the like, which are used together with ethylene glycol as one kind or a mixture of two or more kinds desirable.

Especially, in this invention, it is a cellulose in which the said ester polymer is the ester polymer whose ratio of a C3 or more aliphatic diol residue with respect to all diol residues (henceforth a C3 or more aliphatic diol ratio) is 30 mol% or more. It is preferable from the viewpoint of improving the compatibility of the acylate and the ester polymer and improving the solubility of the ester polymer in the solvent.

It is more preferable that it is 30 mol% or more, and, as for the said C3 or more aliphatic diol ratio, it is especially preferable that it is 50-80 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, and 2-methyl-1,3-propanediol Residue, 1,4-butanediol residue, 1,5-pentanediol residue, 2,2-dimethyl-1,3-propanediol (neopentylglycol) residue, 1,4-hexanediol residue, 1,4-cyclohexane Diol residues; and the like. Among them, examples of the aliphatic diol residue having 3 or more carbon atoms that are preferably used in the present invention include 1,2-propanediol residues, 1,3-propanediol residues, 1,2-butanediol residues, 1,3-butanediol residues, and 2- At least one of methyl-1,3-propanediol residues, 1,4-butanediol residues, 1,5-pentanediol residues, 2,2-dimethyl-1,3-propanediol (neopentylglycol) residues, and more Preferably 1,2-propanediol residues, 1,3-propanediol residues, 1,2-butanediol residues, 1,3-butanediol residues, 2-methyl-1,3-propanediol residues, 1,4-butanediol At least one of the residues is particularly preferably a 1,2-propanediol residue.

Crystallization of the ester polymer can be prevented by using 1,2-propanediol residues or 1,3-propanediol residues.

As a diol residue other than C3 or more aliphatic diol, when an aliphatic diol residue is used, ethylene glycol residue etc. can be used.

In the said ester polymer, an aliphatic diol residue is formed by the aliphatic diol used for mixing.

The said ester polymer may contain aromatic diol residue other than an aliphatic diol residue as a diol residue.

Specific examples of the aromatic diol residues include, for example, bisphenol A residues, 1,2-hydroxybenzene residues, 1,3-hydroxybenzene residues, 1,4-hydroxybenzene residues, 1,4-benzene Dimethanol residues; and the like.

In the said ester polymer, only 1 type of aliphatic diol residue may be contained and 2 or more types may be contained. When two types of aliphatic diol residues are contained in the said ester polymer, it is preferable that a 1, 2- propanediol residue and ethylene glycol residue are contained.

In the said ester polymer, an aromatic diol acid residue is formed from the aromatic diol used for mixing.

The terminal of the said ester type polymer may be a state of the -OH group derived from diol or the -COOH group derived from dicarboxylic acid, without sealing, and what is called terminal sealing by making monocarboxylic acids, monoalcohols, etc. react. It is good also as a -OC (= O) -R <^1> group, -C (= O) -OR <^2> group, and -OR <^3> group, and said R <^1> -R <^3> respectively independently represents an aliphatic group.

When both ends of the said ester type polymer are unsealed, it is more preferable from a viewpoint of suppressing hydrolysis of an ester group than both ends being -COOH both ends are -COOH. That is, when both ends of the said ester polymer are unsealed, it is preferable that the said ester polymer is polyester polyol.

When both ends of the said ester type polymer are sealed, it is preferable that both ends are -OC (= O) -R <^1> group, -C (= O) -OR <^2> group, or -OR <^3> group. It is more preferable that both ends are a group of -OC (= O) -R ¹ , that is, it is more preferable to seal both ends of the ester polymer by reacting with an aliphatic monocarboxylic acid.

At this time, both ends of the ester polymer become aliphatic monocarboxylic acid residues.

Here, each of R ¹ to R ³ independently represents an aliphatic group. The aliphatic group represented by R ¹ to R ³ may not contain an aromatic ring in the aliphatic group, and may be saturated or unsaturated. The aliphatic group represented by R ¹ to R ³ may be any of a chain aliphatic group and a cyclic aliphatic group (for example, cycloalkyl groups, etc.), and in the case of a chain aliphatic group, may be linear or branched. You may also. Although the aliphatic group represented by said R <^1> -R <^3> may have a substituent further as long as it does not contradict the meaning of this invention, if the substituent does not contain an aromatic ring, there is no restriction | limiting in particular, but the aliphatic which does not have a substituent It is preferable that it is a group. Moreover, it is preferable that carbon number of the aliphatic group represented by said R <^1> -R <^3> is 1-21, It is more preferable that it is 1-5, It is especially preferable that it is 1-3, It is more preferable that it is 1 or 2 , 1 is more preferable.

In particular, the R ¹ ~ R ³ is an aliphatic group, a saturated aliphatic group on the chain shown is preferred, more preferably the alkyl group on the chain, and particularly preferably a straight-chain alkyl groups.

That is, when both ends of the said ester polymer are sealed, it is preferable that both ends of the said ester polymer are a C2-C22 acyl group, It is more preferable that it is a C2-C6 acyl group, It is C2 It is especially preferable that it is an acyl group (that is, an acetyl group, a propionyl group, or a butyryl group) of -4, It is more especially preferable that it is an acyl group (that is, an acetyl group or a propionyl group) of 2 or 3 carbon atoms, Even more preferred is an acyl group (ie acetyl group). Moreover, although the acyl group mentioned here contains an aromatic acyl group (so-called aroyl group) other than an aliphatic acyl group, it is preferable that it is an aliphatic acyl group. When carbon number of the acyl group of the both ends of the said ester polymer is 3 or less, volatility will fall, the weight loss by heating of an ester polymer will not become large, and generation | occurrence | production of process contamination and generation | occurrence | production of surface failure can be reduced.

In this case, as monocarboxylic acids used for sealing, it is preferable that they are C2-C22 aliphatic monocarboxylic acid, It is more preferable that it is C2-C6 aliphatic monocarboxylic acid, C2-C4 aliphatic monocarbox It is especially preferable that it is an acid, It is more preferable that it is a C2 or 3 aliphatic monocarboxylic acid, It is more preferable that it is an C2 aliphatic monocarboxylic acid residue.

On the other hand, when both ends of the ester polymer are sealed, both ends of the ester polymer may be a -C (= 0) -OR ² group or a -OR ³ contribution.

In this case, as monoalcohols used for sealing, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, etc. are preferable, and methanol is the most preferable.

Both ends of the ester polymer may each independently represent an -OH group or an -OC (= O) -R ¹ group from the viewpoint of compatibility control with respect to cellulose acylate, provided that a plurality of R ^{1 's} are present. Each independently represent an aliphatic group). In addition, although the said both terminal may contribute the same and different contribution, it is preferable from a viewpoint of the simplicity of synthesis that both are the same group.

It is more preferable that both ends of the ester polymer are -OH group or sealed with acetic acid or propionic acid.

It is difficult for both ends of the ester polymer of the present invention to become acetyl ester residues (sometimes referred to as acetyl residues) by sealing with acetic acid. The handling of the acylate film is preferable, and from the viewpoint of obtaining a cellulose acylate film excellent in humidity stability and polarizing plate durability, it is preferable.

The number average molecular weight of the ester polymer is preferably 500 to 2000, more preferably 700 to 1500, and particularly preferably 700 to 1200. It is preferable that the number average molecular weight of an ester polymer is 500 or more from a viewpoint of an optical expression improvement. Moreover, the compatibility with a cellulose acylate becomes it high that it is 2000 or less, and the bleeding-out at the time of film forming and the heating extending | stretching hardly arises.

The number average molecular weight of the ester polymer of this invention can be measured and evaluated by gel permeation chromatography. Moreover, when the terminal is a polyester polyol without sealing, it can also calculate by the quantity of hydroxyl groups per weight (henceforth a hydroxyl value). The hydroxyl value is determined by measuring the amount (mg) of potassium hydroxide necessary for neutralization of excess acetic acid after acetylation of the polyester polyol.

In addition, the ester polymer which concerns on this invention can be used as a plasticizer.

It is preferable that content of the said ester type polymer with respect to 100 mass parts of cellulose acylates in the cellulose acylate film of this invention is 5-25 mass%, It is more preferable that it is 8-20 mass%, 8-8 It is most preferable that it is 15 mass%.

Dicarboxylic acid residues, diol residues, and the type and ratio of each residue contained in the ester polymer used in the present invention can be measured by a conventional method using H-NMR. Usually, deuterated chloroform can be used as a solvent.

The number average molecular weight of the ester polymer can be measured by a conventional method using GPC (Gel Permeation Chromatography), and, typically, polystyrene can be used as a standard material.

The measurement of the hydroxyl value of the said ester type polymer can apply the acetic anhydride method etc. which were described in Japanese Industrial Standards JISK3342 (paper waste). When a polycondensate is polyester polyol, it is preferable that hydroxyl value is 50-190, and it is more preferable that it is 50-130.

Although the specific example of the said ester polymer is described in the following table | surface, this invention is not limited to the following specific example.

(Synthesis method of ester polymer)

Synthesis of the ester-based polymer used in the present invention may be carried out by thermal melting condensation by a polyesterification reaction or transesterification reaction of diol and dicarboxylic acid by a conventional method, or acid chlorides and glycols of these acids. It can be synthesize | combined easily also by any method of the interfacial condensation method of the. Moreover, about the ester polymer which concerns on this invention, there is a detailed description in Murai Koichi horseshoe "Theory and application of a plasticizer" (Kawashikisha Saiwai Shobo, the first edition of March 1, 1973). Japanese Laid-Open Patent Publication Nos. 05-155809, 05-155810, 5-197073, 2006-259494, and 07-330670 , Japanese Unexamined Patent Application Publication No. 2006-342227, Japanese Unexamined Patent Publication No. 2007-003679, and the like can be used.

(Sugar ester)

In this invention, you may contain at least 1 type of sugar ester compound. As a sugar ester compound, what contains an aromatic is preferable.

The sugar ester compound refers to a compound in which at least one of the substitutable groups (eg, hydroxyl group, carboxyl group) in the polysaccharide constituting the compound and at least one substituent are ester-bonded. That is, the sugar ester compound mentioned here also includes the sugar derivatives of a wide meaning, For example, the compound containing sugar residues, such as gluconic acid, as a structure is included. That is, the sugar ester compound also includes an ester of glucose and carboxylic acid, and also includes an ester of gluconic acid and alcohol.

It is preferable that the group which can be substituted in the polysaccharide which comprises the said sugar ester compound is a hydroxyl group.

In the said sugar ester compound, the structure (henceforth a sugar residue) derived from the polysaccharide which comprises a sugar ester compound is contained. The monosaccharide structure of the said sugar residue is called the structural unit of a sugar ester compound. It is preferable that the structural unit of the said sugar ester compound contains a pyranose structural unit or a furanose structural unit, and it is more preferable that all the sugar residues are a pyranose structural unit or a furanose structural unit. Moreover, when the said sugar ester is comprised with polysaccharide, it is preferable to contain a pyranose structural unit or a furanose structural unit together.

Although the sugar residue of the said sugar ester compound may be derived from 5 monosaccharides or may be derived from 6 monosaccharides, it is preferable that it is derived from 6 monosaccharides.

It is preferable that it is 2-4, as for the number of the structural units contained in the said sugar ester compound, it is more preferable that it is 2-3, and it is especially preferable that it is two. That is, it is preferable that the sugar which comprises the said sugar ester compound is a disaccharide-a tetrasaccharide, It is more preferable that it is a disaccharide-a trisaccharide, It is especially preferable that it is a disaccharide.

In this invention, it is more preferable that the said sugar ester compound is a sugar ester compound containing 2-4 pyranose structural units or furanose structural units in which at least one hydroxyl group was esterified, and a hydroxyl group of It is more preferable that at least one is a sugar ester compound containing two esterified pyranose structural units or two furanose structural units.

Examples of the monosaccharide or a sugar containing 2 to 4 monosaccharide units include, for example, erythrose, treose, ribose, arabinose, xylose, lyxose, allose, altrose, glucose, fructose. Lactose, Mannose, Gulos, Idoose, Galactose, Taloose, Trehalose, Isotrehalose, Neotrehalose, Trehalosamine, Cozibiose, Nigerose, Maltose, Multitol, Iso Maltose, Sophorose, Laminaribiose, Cellobiose, Genthiobiose, Lactose, Lactosamine, Lactitol, Lactulose, Melibiose, Primeberose, Lutinose, Cellobiose, Sucrose, Sucralose, Tranose, Visia North, Cellotlios, Cacotlios, Gentianos, Isomaltrios, Isopanos, Maltotrios, Manninotrios, Melitchoses, Panos, Planteose, Raffinose, Solartrio , Faroe Valley Stadium, lycopene, and the like Tetra Osu, Osu malto Tetra, stachyose, malto-penta Oscar, Svalbard Vere course, malto hexa Osu, xylitol, sorbitol.

Preferably, it is ribose, arabinose, xylose, lixose, glucose, fructose, mannose, galactose, trehalose, maltose, cellobiose, lactose, sucrose, sucralose, xylitol, sorbitol, and more preferably. Preferably, arabinose, xylose, glucose, fructose, mannose, galactose, maltose, cellobiose, sucrose, and particularly preferably xylose, glucose, fructose, mannose, galactose, maltose, Cellobiose, sucrose, xylitol, sorbitol.

As a preferable example of the substituent of the said sugar ester compound, an alkyl group (preferably C1-C22, More preferably, it is C1-C12, Especially preferably, it is a C1-C8 alkyl group, for example, a methyl group, an ethyl group, a propyl) Group, hydroxyethyl group, hydroxypropyl group, 2-cyanoethyl group, benzyl group, etc., aryl group (preferably C6-C24, more preferably 6-18, Especially preferably, 6-12 aryl Groups, for example, a phenyl group, a naphthyl group, an acyl group (preferably a C1-C22, more preferably a C2-C12, especially preferably an C2-C8 acyl group, for example, an acetyl group, Propionyl group, butyryl group, pentanoyl group, hexanoyl group, octanoyl group, benzoyl group, toluyl group, phthalyl group, etc.), an amide group (preferably C1-C22, more preferably C2-C12, especially preferably Has 2 carbon atoms Amides of 8 to 8, for example formamide groups, acetamide groups, etc., imide groups (preferably 4 to 22 carbon atoms, more preferably 4 to 12 carbon atoms, particularly preferably 4 to 8 carbon atoms, For example, a succinimide group, a phthalimide group, etc. are mentioned. Especially, an alkyl group or an acyl group is more preferable, a methyl group, an acetyl group, a propionyl group, a butyryl group (among these, i-butyryl group is preferable) and a benzoyl group are more preferable, and it contains at least one of an acetyl group and a butyryl group. It is especially preferable to make it, and it is more preferable to contain only an acetyl group or to contain both an acetyl group and a butyryl group.

The compound shown below is mentioned as a sugar ester compound used for this invention. However, the sugar ester compound which can be used by this invention is not limited to these. In addition, in the following structural formula, R respectively independently represents arbitrary substituents, and some R may be same or different.

In addition, as said sugar ester compound, Unexamined-Japanese-Patent No. 2001-247717, Unexamined-Japanese-Patent No. 2005-515285, International Publication WO2007 / 125764, International Publication WO2009 / 011228, International Publication WO2009 / 031464 You may use the sugar ester compound described in an arc etc.

As a method for obtaining the sugar ester compound, a commercially available ester derivatization method can be obtained commercially from Tokyo Chemical Co., Ltd., Aldrich Co., Ltd., or commercially available carbohydrates (for example, JP-A-A). The method of Unexamined-Japanese-Patent No. 8-245678) can be synthesize | combined.

As for the said sugar ester compound, the number average molecular weight becomes like this. Preferably it is 200-3500, More preferably, it is 420-3000, Especially preferably, the range of 450-2000 is preferable.

It is preferable to contain 2-35 mass% of the said sugar ester compound with respect to a cellulose acylate, It is more preferable to contain 5-20 mass%, It is especially preferable to contain 10-15 mass%.

(Nitrogen-containing ring compound)

The film of this invention may contain at least 1 type of nitrogen-containing ring compound. As a nitrogen-containing ring compound, it is preferable to contain an aromatic. By containing a nitrogen-containing ring compound, the retardation value can be expressed more effectively.

The nitrogen-containing ring compound is any of pyridine, pyrimidine, triazine and purine as a mother nucleus, and an alkyl group, alkenyl group, alkynyl group, amino group, and amide group (optionally through an amide bond) at any position where the mother nucleus can be substituted. It means having a structure in which the acyl group is bonded), an aryl group, an alkoxy group, a thioalkoxy group, an alkyl or arylthio group (a group in which an alkyl group or an aryl group is connected via a sulfur atom), or a heterocyclic group as a substituent. However, the substituent of the mother nucleus of these said nitrogen-containing ring compounds may be substituted by the other substituent, and there is no restriction | limiting in particular as said other substituent. For example, when the mother nucleus is substituted with an amino group, the amino group is substituted with an alkyl group (the alkyl groups may be connected to form a ring) or -SO ₂ R '(R' represents an arbitrary substituent). You may be.

It is preferable that content of the said nitrogen-containing cyclic compound is less than 7 mass% with respect to the said cellulose acylate, It is more preferable that it is 1-5 mass%, and, as for the film of this invention, it is especially preferable that it is 1-3 mass%. .

The film of this invention may contain what is called a retardation expression agent conventionally well-known as said nitrogen-containing ring compound. By employing a retardation expression agent, a high retardation expression property can be obtained at a low draw ratio. On the other hand, since the film of this invention is manufactured by the manufacturing method of the said cellulose acylate film mentioned later, even if it does not contain these retardation expression agents, retardation expression property is favorable.

Although there is no restriction | limiting in particular as said retardation expression agent, What consists of rod-shaped compounds, What consists of compounds which have cyclic structures, such as a cycloalkane or an aromatic ring, The compound which shows retardation expression property in the said non-phosphate ester type compound Can be mentioned. As a compound which has a cyclic structure, a nitrogen-containing cyclic compound is preferable. As the rod-like compound or the nitrogen-containing ring compound, a compound having at least two aromatic rings can be preferably used as the retardation expression agent.

Moreover, you may use together two or more types of retardation expression agents.

It is preferable that a retardation expression agent does not have absorption in a visible region substantially.

As a retardation expression agent, the compound described in Unexamined-Japanese-Patent No. 2004-50516, the 2007-86748, and the compound of Unexamined-Japanese-Patent No. 2010-46834 can be used, for example, The present invention is not limited to these.

Examples of the nitrogen-containing ring compound include compounds described in European Patent Application Publication No. 0911656A2, triazine compounds described in Japanese Patent Application Laid-Open No. 2003-344655, and Japanese Patent Laid-Open Nos. 2008-150592 to [0108]. The triphenylene compound described in] can also be used preferably.

Moreover, the compound as described in [0062]-[0081] of Unexamined-Japanese-Patent No. 2012-144627 can also be used preferably.

A nitrogen-containing ring compound can be synthesized by a known method such as the method described in JP-A-2003-344655 and the method described in JP-A-2005-134884.

In addition to the nitrogen-containing ring compound described above, a rod-like compound having a linear molecular structure can also be preferably used. For example, the rod-like compound described in Japanese Unexamined Patent Publication No. 2008-150592 [0110] to [0127] can be preferably used. have.

Although the specific example of a nitrogen-containing ring compound is given to the following, this invention is not limited by the following specific example.

<Other additives>

In addition to the above-mentioned, the cellulose acylate film used by this invention can be made to contain the additive which can be added to a normal cellulose acylate film.

As these additives, the additive which has intrinsic birefringence | negative birefringence, microparticles | fine-particles, a retardation expression agent, antioxidant, a thermal degradation inhibitor, a coloring agent, a ultraviolet absorber, etc. are mentioned, for example.

About the said other additive, the compound described in international publication WO2008-126535 can be used preferably.

(Unique birefringence denier additive)

Intrinsic birefringence may contain the negative additive in the film of this invention. The compound which has negative intrinsic birefringence which the said intrinsic birefringence can use as a denier additive is demonstrated below.

The compound which has said negative intrinsic birefringence means the material which shows negative intrinsic birefringence with respect to the specific direction of a film in a cellulose acylate film. In this specification, negative intrinsic birefringence refers to the birefringence property. In addition, whether or not it has negative intrinsic birefringence can be understood, for example, by measuring the birefringence of the film in a system in which the compound is not added with a birefringence system and comparing the differences.

The compound having negative intrinsic birefringence of the present invention is not particularly limited, and known compounds showing negative intrinsic birefringence can be used, for example, in JP 2010-46834 A. The compound disclosed etc. can be used preferably.

Examples of the compound having negative intrinsic birefringence include polymers having negative intrinsic birefringence, acicular fine particles having negative intrinsic birefringence (containing acicular fine particles of polymer having negative intrinsic birefringence), and the like. Hereinafter, the polymer which has a negative intrinsic birefringence which can be used for this invention is demonstrated.

The polymer having negative intrinsic birefringence refers to a polymer in which the light refractive index in the alignment direction becomes smaller than the light refractive index in the direction orthogonal to the alignment direction when light enters the layer formed by the molecule having a monoaxial orientation.

As a polymer having such a negative intrinsic birefringence, as a negative polymer, a polymer having a specific cyclic structure (a disk-like ring such as an aliphatic aromatic ring or a heteroaromatic ring) in the side chain (for example, polystyrene, poly (4) Styrene-based polymers such as -hydroxy) styrene, styrene-maleic anhydride copolymer, polyvinylpyridine and the like, (meth) acrylic polymers such as polymethylmethacrylate, and cellulose ester-based polymers (except those having birefringence positive) ), Polyester polymers (except birefringence is positive), acrylonitrile polymers, alkoxysilyl polymers, or polyunsaturated (binary, ternary, etc.) copolymerized polymers thereof. These may be used alone, or two or more kinds may be used in combination. Moreover, when it is a copolymer, a block copolymer may be sufficient and a random copolymer may be sufficient.

Among these, polymers having a specific cyclic structure, (meth) acrylic polymers and alkoxysilyl polymers are more preferable, and polystyrene, polyhydroxystyrene, polyvinylpyridine and (meth) acrylic polymers are particularly preferable.

When the polymer which has the said specific cyclic structure is added, since the expression of Rth of the cellulose acylate film after film forming can be improved, it is preferable.

As a polymer which has the said specific cyclic structure, the polymer which has the aliphatic aromatic ring described in Unexamined-Japanese-Patent No. 2010-46834 in a side chain can be used preferably. Especially, polystyrene and poly (4-hydroxy) styrene are preferable, and the copolymer of polystyrene and poly (4-hydroxy) styrene is more preferable. It is preferable that it is 10/90-100/0, and, as for the copolymerization ratio (molar ratio) of the copolymer of the said polystyrene and poly (4-hydroxy) styrene, it is more preferable that it is 20/80-90/10.

In addition, as a polymer which has the said specific cyclic structure, the polymer which has heteroaromatic rings, such as polyvinylpyridine, in a side chain can also be used preferably.

When the said (meth) acrylic-type polymer is added, transparency of the cellulose acylate film after film forming is excellent, moisture permeability is also very low, and shows the outstanding performance as a protective film for polarizing plates. About the said (meth) acrylic-type polymer, the compound described in Unexamined-Japanese-Patent No. 2009-1696 and WO2008-126535 can be used preferably. Moreover, the said (meth) acrylic-type polymer may have an aliphatic aromatic ring and a hetero aromatic ring in a side chain.

When the compound having negative intrinsic birefringence is a polymer having negative intrinsic birefringence, the weight average molecular weight is preferably 500 to 100,000, more preferably 700 to 50,000, and particularly preferably 700 to 100000.

If molecular weight is 500 or more, volatilization is favorable, and if molecular weight is 100,000 or less, compatibility with a cellulose acylate resin will be favorable, and the film forming property of a cellulose acylate film will become favorable, and all are preferable.

It is preferable to add 0-20 mass% of compounds which have the said intrinsic birefringence with respect to the said cellulose acylate to the film of this invention, It is more preferable to add 0-15 mass%, It is more preferable to add 0-10 mass% It is particularly preferable to.

On the other hand, since the film of this invention is manufactured by the manufacturing method of the said cellulose acylate film mentioned later, even if it does not contain the compound which has these comparatively expensive negative intrinsic birefringence, reverse wavelength dispersion property is large. Therefore, it is preferable that the film of this invention has a small addition amount of the compound which has negative intrinsic birefringence from a viewpoint of lowering manufacturing cost.

(Fine particles)

As the fine particles used in the present invention, examples of inorganic compounds include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate and magnesium silicate. And calcium phosphate.

It is preferable that microparticles | fine-particles contain silicon from the point that haze becomes low, and silicon dioxide is especially preferable.

5-50 nm is preferable and, as for the average particle diameter of the primary particle of microparticles | fine-particles, 7-20 nm is more preferable. It is preferable to contain these mainly as a secondary aggregate of particle size 0.05-0.3 micrometers.

The fine particles of silicon dioxide are, for example, trade names of aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600, NAX50 (above Nippon Aerosil Co., Ltd.) It is commercially available and can be used.

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

Examples of the polymer include a silicone resin, a fluororesin, and an acrylic resin. A silicone resin is preferable, and it is especially preferable to have a three-dimensional network structure, for example, Tospur 103, 105, 108, 120, 145, 3120, and 240 (above Toshiba Silicone Co., Ltd.) Commercially available) and can be used.

Among these, aerosil 200V and aerosil R972V are particularly preferably used because the effect of lowering the coefficient of friction is great while keeping the haze of the cellulose derivative film low.

It is preferable that content of these microparticles | fine-particles with respect to the said cellulose acylate in the cellulose film of this invention is 0.05-1 mass%, and 0.1-0.5 mass% is especially preferable. In the case of a cellulose derivative film having a multi-layer structure by a covalent bonding method, it is preferable that the surface contains fine particles in the added amount.

(Antioxidants, Thermal Degradants)

In this invention, what is generally known can be used as antioxidant and a thermal deterioration inhibitor. In particular, those which are lactone-based, sulfur-based, phenol-based, double bond-based, hindered amine-based and phosphorus-based compounds can be preferably used. About the said antioxidant and the thermal deterioration agent, the compound described in international publication WO2008-126535 can be used preferably.

(coloring agent)

In this invention, you may use a coloring agent. The colorant means a dye or a pigment, but in the present invention, it refers to an effect of adjusting the color tone of the liquid crystal display to a blue color tone, or adjusting the yellow index and reducing haze. About the said coloring agent, the compound described in international publication WO2008-126535 can be used preferably.

(Peeling accelerator)

In this invention, you may use a peeling accelerator. As a peeling promoter, the compound of Unexamined-Japanese-Patent No. 2011-183759 can be used suitably.

(Layer Structure of Cellulose Acylate Film)

Although the film of this invention may be a single | mono layer film, and may have a laminated structure of two or more layers, it is preferable that it is a single | mono layer film.

(Film thickness)

The film thickness of this invention is 20-60 micrometers. Thus, by setting it as a thin cellulose acylate film, a thin polarizing plate and a thin liquid crystal display device are obtained. 30-55 micrometers is preferable and, as for the film thickness of the film of this invention, it is more preferable that it is 30-50 micrometers. 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. The film thickness in this invention says an average film thickness.

(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.

(ΔM)

In the cellulose acylate film of the present invention, the difference between the equilibrium moisture content at 25 ° C. 80% after immersion in 40 ° C. pure water for 24 hours and the equilibrium moisture content at 25 ° C. 80% before immersion is 1.0% or less, and 0.5% The following is preferable. By making the difference in equilibrium moisture content small in this way, even if it adheres to water, the nonuniformity by dew condensation will not generate | occur | produce, and appropriate display performance will be obtained. Equilibrium moisture content is a value measured by Karl Fischer method.

(Re, Rth)

In the film of the present invention, the retardation in the in-plane and film thickness directions at a wavelength of 590 nm satisfies the following formulas (I) and (II).

Formula (I) 30 nm ≤ Re (590) ≤ 90 nm

(In Formula (I), Re (590) shows in-plane direction retardation in wavelength 590nm.)

Formula (II) 100 nm ≤ Rth (590) ≤ 150 nm

(In formula (II), Rth (590) represents the retardation of the film thickness direction in wavelength 590nm.)

It is preferable to express retardation in such a range from the viewpoint of the improvement of contrast and black color change of a liquid crystal display device.

It is preferable that it is 40-90 nm, and, as for said Re (590), it is more preferable that it is 45-60 nm.

It is preferable that it is 100-200 nm, and, as for said Rth (590), it is more preferable that it is 110-130 nm.

(Rth / d)

It is preferable that the film of this invention satisfy | fills Formula (III) 2.0 <Rth (590) / d <5.0. Here, d represents a film thickness (micrometer). By setting it as such a range, predetermined | prescribed retardation is expressed even if it thins a cellulose acylate film. 2.5 to 4.0 are preferable and, as for Rth (590) / d, 2.8 to 3.5 are more preferable.

Re (λ) and Rth (λ) in the present specification indicate in-plane retardation and retardation in the thickness direction, respectively, at the wavelength λ. In this specification, when there is no description in particular, wavelength (lambda) shall be 590 nm. Re (λ) is measured by injecting light having a wavelength of λ nm in the film normal direction in KOBRA 21ADH (manufactured by Oji Measuring Instruments Co., Ltd.). Rth (λ) is the Re (λ) as the in-plane slow axis (determined by KOBRA 21ADH) as the inclination axis (rotation axis) (when there is no ground axis, any direction in the film plane is the rotation axis) Six points were measured by injecting light having a wavelength of λ nm from the inclined direction in 10 degree steps from the normal direction to the 50 degree side with respect to the film normal direction, and measuring six points, and the assumption of the measured retardation value and the average refractive index, and Based on the input film thickness value, KOBRA 21ADH calculates. In addition, the retardation value is measured from two arbitrary directions by making a slow axis into an inclination axis (rotation axis) (when there is no ground axis, making arbitrary directions in a film plane), and the assumption value of the value and an average refractive index. And Rth can also be calculated from the following formula (A) and formula (B) based on the input film thickness value. Here, the hypothetical value of the average refractive index may be a polymer handbook (JOHN WILEY & SONS, INC) and catalog values of various optical films. If the value of the average refractive index is not already known, it can be measured with an Abbe refractometer. The value of the average refractive index of the main optical film is illustrated below: cellulose acylate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethylmethacrylate (1.49), polystyrene (1.59). KOBRA 21ADH calculates nx, ny, and nz by inputting the assumption value and film thickness of these average refractive indices. From the calculated nx, ny, and nz, Nz = (nx-nz) / (nx-ny) is further calculated.

The formula (A)

Here, Re (theta) represents the retardation value in the direction which inclined angle (theta) from a normal direction, nx, ny, and nz represent the refractive index of each main-axis orientation of a refractive index ellipsoid, and d represents a film thickness.

Rth = ((nx + ny) / 2-nz) × d Formula (B)

Moreover, at this time, the average refractive index n is needed as a parameter, and the value measured by the Abbe refractometer ("Abe refractometer 2-T" by the Atago Co., Ltd.) was used.

(Internal haze)

The internal haze of the cellulose acylate film of this invention is 0.05% or less.

Haze represents haze value (%) measured according to JISK7136.

The internal haze of the film of this invention was dripped the glycerol drop on both surfaces of the obtained cellulose acylate film, and was measured in the state which pinched on both sides by two glass plates of 1.3 mm thickness (made by MICRO SLIDE GLASS part number S 9213, MATSUNAMI). From the haze value (%), the value (%) which subtracted the haze measured in the state which dripped the glycerin several drops between two glass sheets is shown.

The haze of the cellulose acylate film of this invention was measured in the same environment in the film left for 24 hours in 23 degreeC and 55% of relative humidity conditions using the turbidity meter (NDH2000, Nippon Denshoku Industries Co., Ltd.). .

It is preferable that it is 0.035% or less, as for the internal haze of the cellulose acylate film of this invention, it is more preferable that it is 0.03% or less, It is still more preferable that it is 0.025% or less.

The lower one is generally considered to be preferable. Moreover, only low overall haze is inadequate for front contrast improvement, and adjusting an internal haze to the said range is preferable from a viewpoint of the front contrast improvement of a liquid crystal display device.

[Method for producing cellulose acylate film]

The cellulose acylate film of the present invention can be produced according to a known method.

Moreover, in this invention, the process of forming the polymer solution which has the cellulose acylate of the total substitution degree 2.0-2.55, a solvent, and the compound containing an aromatic in film form, and after extending | stretching the film, a film thickness is 20-60 micrometers. The manufacturing method of the cellulose acylate film including the process of controlling and extending | stretching so that it may become, and further including the process of water-processing the stretched film is disclosed. These details will be described below.

The manufacturing method of a cellulose acylate film can form a film containing a cellulose acylate using the solution casting film forming method or the melt film forming method. From a viewpoint of improving the surface shape of a film, it is preferable that the manufacturing method of a cellulose acylate film includes the process of forming a film containing a cellulose acylate by solution casting film forming.

Hereinafter, although the case where a solution casting film forming method is used for the manufacturing method of a cellulose acylate film is demonstrated to an example, the manufacturing method of a cellulose acylate film is not limited to the solution casting film forming method. Moreover, a well-known method can be used about the case of using the said melt film forming method as a manufacturing method of the said cellulose acylate film.

<Polymer solution>

In the solution casting film formation method, a web is formed using the said cellulose acylate and the polymer solution (cellulose acylate solution) containing various additives as needed. In this invention, it is preferable that an additive is mix | blended normally and the compound containing an aromatic is mix | blended as an additive. Below, the polymer solution (Hereinafter, it may be suitably called a cellulose acylate solution or dope) which can be used for a solution casting film forming method is demonstrated.

(menstruum)

The cellulose acylate used in the present invention is dissolved in a solvent to form a dope, which is cast on the substrate to form a film. At this time, since it is necessary to evaporate the solvent after extrusion or casting, it is preferable to use a volatile solvent.

Further, it does not react with a reactive metal compound, a catalyst, or the like, and does not dissolve the flexible substrate. Moreover, you may mix and use 2 or more types of solvent.

Moreover, you may mix, after melt | dissolving a cellulose acylate and the reactive metal compound which can be hydrolyzed polycondensation in each other solvent.

Here, the organic solvent which has favorable solubility with respect to the said cellulose acylate is called a good solvent, and shows the main effect in dissolution, The organic solvent used in large quantities among these is a main (organic) solvent or a main (organic) It is called a solvent.

Examples of the good solvent include ketones such as acetone, methyl ethyl ketone, cyclopentanone, and cyclohexanone, tetrahydrofuran (THF), 1,4-dioxane, 1,3-dioxolane, and 1,2-dime In addition to ethers such as oxyethane, esters such as methyl formate, ethyl formate, methyl acetate, ethyl acetate, amyl acetate and γ-butyrolactone, methylcellosolve, dimethylimidazolinone, dimethylformamide, and dimethylacetyl Amide, acetonitrile, dimethyl sulfoxide, sulfolane, nitroethane, methylene chloride, acetoacetate, and the like, although 1,3-dioxolane, THF, methyl ethyl ketone, acetone, methyl acetate and methylene chloride are preferred. Do.

It is preferable to make dope contain 1-40 mass% C1-C4 alcohol other than the said organic solvent.

They gel the web (the name of the dope film after flexible dope of cellulose acylate on the support is made to the web) after the dope is pliable to the metal support, and the solvent begins to evaporate and the proportion of alcohol increases. It is used as a gelling solvent which makes it easy to peel off from, or when the ratio thereof is small, it also plays a role of promoting dissolution of cellulose acylate in a non-chlorinated organic solvent, and inhibits gelation, precipitation and increase in viscosity of the reactive metal compound. There is also a role.

Examples of the alcohol having 1 to 4 carbon atoms include methanol, ethanol, n-propanol, Iso-propanol, n-butanol, sec-butanol, tert-butanol, and propylene glycol monomethyl ether.

Among these, ethanol is preferable from the viewpoint of excellent dope stability, relatively low boiling point, good dryness and no toxicity. These organic solvents alone do not have solubility in cellulose acylate and are referred to as poor solvents.

In the present invention, since the cellulose acylate constituting the cellulose acylate film contains a hydrogen bondable functional group such as a hydroxyl group, an ester or a ketone, it is 5 to 30% by mass in the total solvent, more preferably 7 to 25% by mass. More preferably, it is preferable to contain 10-20 mass% alcohol from a viewpoint of reducing peeling load from a flexible support body.

By adjusting alcohol content, the expression property of Re and Rth of the cellulose acylate film manufactured by the manufacturing method of the said cellulose acylate film can be made easy to adjust. Specifically, by increasing the alcohol content or by setting the drying temperature (heat treatment temperature) before stretching in the method for producing the cellulose acylate film described later to be relatively low, increasing the reach of Re or Rth, etc. It becomes possible.

In addition, in the present invention, containing a small amount of water is also effective for increasing the viscosity of the solution, the film strength in the wet film state at the time of drying, or the dope strength at the time of drum casting casting, for example, the whole solution. It may contain 0.1-5 mass% with respect to it, More preferably, you may contain 0.1-3 mass%, and you may contain 0.2-2 mass% especially.

The example of the combination of the organic solvent used preferably as a solvent of the polymer solution in this invention is illustrated in Unexamined-Japanese-Patent No. 2009-262551.

If necessary, a non-halogen-based organic solvent may be used as the main solvent, and detailed descriptions are described in the Invention Association Publication (Publication No. 2001-1745, issued March 15, 2001, Invention Association).

5-40 mass% is preferable, as for the cellulose acylate density | concentration in the polymer solution in this invention, 10-30 mass% is more preferable, and 15-30 mass% is the most preferable.

The cellulose acylate concentration can be adjusted to a predetermined concentration in the step of dissolving cellulose acylate in a solvent. Moreover, after preparing the solution of low concentration (for example, 4-14 mass%) beforehand, you may concentrate by evaporating a solvent etc. Moreover, after preparing a high concentration solution previously, you may dilute. Moreover, the density | concentration of a cellulose acylate can also be reduced by adding an additive.

The time of adding an additive can be suitably determined according to the kind of additive.

The most preferable solvent is a mixed solvent having a ratio of methylene chloride: ethyl alcohol of 95: 5 to 80:20 as a solvent for dissolving cellulose acylate, which is a preferable high molecular compound satisfying such conditions at high concentration. Or a mixed solvent of methyl acetate: ethyl alcohol 60: 40 to 95: 5 is also preferably used.

<Details of each process>

(1) melting process

A step of forming a dope by dissolving the cellulose acylate and an additive while stirring in a dissolving kiln in an organic solvent mainly containing a good solvent for cellulose acylate, or a step of mixing the additive solution in a cellulose acylate solution to form a dope. to be.

To dissolve the cellulose acylate, a method carried out at atmospheric pressure, a method carried out below the boiling point of the main solvent, a method carried out by pressing above the boiling point of the main solvent, JP-A-9-95544, JP-A-JP Various dissolution methods, such as the method performed by the cooling dissolution method as described in Unexamined-Japanese-Patent No. 9-95538, the method performed at high pressure as described in Unexamined-Japanese-Patent No. 11-21379, etc. Although it can use, the method of pressing and performing especially above the boiling point of a main solvent is preferable.

As for the density | concentration of the cellulose acylate in dope, 10-35 mass% is preferable. Additives are added to the dope during or after the dissolution to dissolve and disperse, and then filtered through a filter medium, degassed and sent to the next step by the feed pump.

(2) flexible process

Flexible position on the metal support, such as an endless metal belt, for example, a stainless steel belt, or a rotating metal drum, which feeds the dope to the pressure die through a liquid feeding pump (for example, a pressure metering gear pump) and transfers indefinitely. It is a process of casting dope from a pressurized die slit.

The pressurized die which can adjust the slit shape of the die | dye part of die | dye and is easy to make film thickness uniform is preferable. There exist a coat hanger die, a T die, etc. in pressurization die | dye, and all are used preferably. The surface of the metal support is mirror-finished. In order to increase the film forming speed, two or more press dies may be formed on the metal support, and the doping amount may be divided to be laminated. Alternatively, it is also preferable to obtain a laminated film by a covalent bonding method in which a plurality of doughs are simultaneously flexible.

(3) solvent evaporation process

It is a process of heating a web (the state before it becomes a finished product of a cellulose acylate film, so that it still contains a lot of solvent in this way) on a metal support body, and evaporating a solvent until a web can peel from a metal support body.

In order to evaporate the solvent, there is a method of blowing air from the web side, and / or a method of heat transfer from the back surface of the metal support by liquid, a method of heat transfer from front and back by radiant heat, and the like. This is favorable and preferable. Moreover, the method of combining them is also preferable. In the case of back surface liquid heat transfer, it is preferable to heat below the boiling point of the main solvent of the dope use organic solvent or the organic solvent which has the lowest boiling point.

(4) peeling process

It is a process of peeling the web in which the solvent evaporated on the metal support body at a peeling position. The peeled web is sent to the next process. In addition, when the amount of residual solvent (following formula) of the web at the time of peeling is too large, it is difficult to peel, or on the contrary, if the film is peeled off after being sufficiently dried on a metal support, part of the web may be peeled off in the middle.

Here, there is a gel casting method (gel casting) as a method of increasing the film forming rate (the film forming rate can be increased by peeling as much of the residual solvent amount as possible). For example, there is a method of adding a poor solvent to cellulose acylate in dope, gelling after dope casting, and gelling by lowering the temperature of the metal support. By gelling on a metal support and increasing the strength of the film at the time of peeling, the film formation speed can be increased by advancing the peeling.

Although the amount of residual solvent at the time of peeling a web on a metal support body peels in the range of 5-150 mass% according to the strength of dry conditions, the length of a metal support, etc., it is economical when it peels at a more time point. The balance of speed and quality determines the amount of residual solvent at the time of peeling. In this invention, it is preferable to make temperature in the peeling position on the said metal support body into -50-40 degreeC, 10-40 degreeC is more preferable, and it is most preferable to set it as 15-30 degreeC.

Moreover, it is preferable to make the residual solvent amount of the web in the peeling position into 10-150 mass%, and also to set it as 10-120 mass%.

The residual solvent amount can be represented by the following formula.

Residual solvent amount (mass%) = [(M-N) / N] × 100

Here, M is mass at the arbitrary time of a web, N is mass when it dried at 110 degreeC for 3 hours that is mass M.

(5) drying or heat treatment process, stretching process

In the manufacturing method of the cellulose acylate film of this invention, an extending process is performed with respect to the film after peeling. Moreover, it is preferable to implement the said extending process at the temperature of Tg-20 degreeC-Tg degreeC from a viewpoint of improving the optical expression property with respect to the film thickness of the cellulose acylate film obtained. In addition, Tg represents the glass transition temperature (unit: degreeC) of the cellulose acylate film of this invention, and means the temperature which tanδ shows a peak when the dynamic viscoelasticity tanδ of the cellulose acylate film when 0% of residual volatile content is measured. do.

After the said peeling process, drying a web using the drying apparatus which alternately passes a web through the roll arrange | positioned in the drying apparatus, and conveys, and / or the tenter apparatus which conveys while clipping and extending both ends of a web with a clip. desirable.

In the manufacturing method of the said cellulose acylate film, you may heat-process a web before extending | stretching, and it is not necessary to heat-process.

Moreover, it is preferable that drying or heat processing temperature is 30 minutes or less, It is more preferable that it is 20 minutes or less, It is especially preferable that it is about 10 minutes.

As a means of drying and heat treatment, it is common to blow hot air on both sides of the web, but there is also a means of heating microwaves instead of wind. Temperature, air volume, and time differ according to the solvent to be used, and what is necessary is just to select conditions suitably according to the kind and combination of solvents used.

In the manufacturing method of the said cellulose acylate film, although you may extend | stretch in any direction of the film conveyance direction (henceforth a longitudinal direction) and the direction orthogonal to a film conveyance direction (henceforth a horizontal direction), it extends at least in a horizontal direction. It is preferable from the viewpoint of expressing a desired retardation. Stretching may be performed in one stage or may be performed in multiple stages.

It is preferable that the draw ratio in extending | stretching to a film conveyance direction is 0 to 20%, It is more preferable that it is 0 to 15%, It is especially preferable that it is 0 to 10%. The draw ratio (extension) of the cellulose acylate web at the time of extending | stretching can be achieved by the peripheral speed difference of a metal support speed and peeling speed (peel roll draw). For example, when using the apparatus which has two nip rolls, a cellulose acylate film is preferable in a conveyance direction (vertical direction) by making the rotation speed of the nip roll of an exit side faster than the rotation speed of the nip roll of an inlet side. Can be extended. By performing such extending | stretching, the expression property of retardation can be adjusted.

In addition, "stretch ratio (%)" here means what is calculated | required by the following formula | equation.

Stretch ratio (%) = 100 × {(length after stretching)-(length before stretching)} / length before stretching

It is preferable that the draw ratio in extending | stretching to the direction orthogonal to a film conveyance direction is more than 20%, It is more preferable that it is more than 20%-60% or less, It is especially preferable that it is 25 to 55%, 25-50 It is more preferable that it is%.

Moreover, in this invention, it is preferable to extend | stretch using a tenter apparatus as a method of extending | stretching in the direction orthogonal to a film conveyance direction.

In the manufacturing method of the said cellulose acylate film, it is preferable that extending | stretching temperature is Tg-20 degreeC-Tg.

Moreover, in the more preferable aspect of the manufacturing method of the said cellulose acylate film, it is extended by extending | stretching in the range of the said extending | stretching temperature using the cellulose acetate (especially the cellulose acetate of acetyl substitution degree 2.0-2.5) of low acetyl substitution degree, The haze resulting from extending | stretching can also be suppressed. Although not bound by any theory, when cellulose acetate having a low acetyl substitution degree is used as the cellulose acylate, the cellulose acetate having a low acetyl substitution degree is an ester polymer composed of the aliphatic dicarboxylic acid residue and aliphatic diol residue. Since the refractive index difference is large, it is expected that scattering in the film is less likely to occur. Moreover, haze can further be suppressed by selecting the ester type polymer having a high compatibility with cellulose acetate having low acetyl substitution degree. As a result, the internal haze of the film obtained by the manufacturing method of the said cellulose acylate film can be made easy to control to the said preferable range.

In the manufacturing method of the film of this invention, it is preferable to extend | stretch at Tg-10 degreeC-Tg + 40 degreeC, in order to suppress craze generation and not to express internal haze. Tg-5 degreeC-Tg + 30 degreeC is more preferable, and Tg-Tg + 20 degreeC is especially preferable. By making extending | stretching temperature into the said temperature range, internal haze rise can be suppressed.

Moreover, you may dry after extending | stretching process and before the wet heat processing process mentioned later. When drying after extending | stretching process and before the wet heat processing process mentioned later, drying temperature, drying air quantity, and drying time differ according to the solvent to be used, What is necessary is just to select a dry condition suitably according to the kind and combination of used solvent. In this invention, it is preferable from the viewpoint of raising the front contrast at the time of attaching the film of this invention to the liquid crystal display device that the drying temperature after the extending process before the wet heat processing process mentioned later is lower than the extending temperature of an extending process.

(6) water treatment process

In this invention, the cellulose acylate film after extending | stretching is water-processed. As water treatment, it is preferable to immerse in water after extending | stretching. 25-85 degreeC is preferable and, as for the temperature of water, 35-80 degreeC is more preferable. It is preferable that it is 5 second or more, and, as for the immersion time in water, it is more preferable that it is 5 second-12 hours. By setting it as 5 seconds or more, the effect of this invention is exhibited more effectively, and productivity is improved by setting it as 12 hours or less. Moreover, although the effect of this invention tends to be acquired even if immersion time is short by raising the temperature of the water to be immersed, when temperature is made high too much, there exists a tendency for wrinkles to be caught easily at the time of conveyance. Moreover, the display nonuniformity by dew condensation can be suppressed in each stage by making water treatment temperature into 85 degrees C or less.

In this invention, it is preferable to adjust so that the elongation rate of the conveyance direction of the film at the time of water treatment may be 1% or less, and it is more preferable to adjust so that it may become 0.5% or less.

The water used for these immersion may be water substantially. Substantially, water means that 60 mass% or more consists of water, and may contain the organic solvent, plasticizer, surfactant, etc. which are described below other than water. As a preferable organic solvent, a C1-C10 water-soluble organic solvent is mentioned. However, as for the water used for immersion in this invention, 90 mass% or more is water, More preferably, 95 mass% or more is water, Most preferably, pure water is used. The water used in the following technique may also be substantially water, and is not limited to pure water.

(7) Drying process

The water-treated cellulose acylate film may be cooled to approximately room temperature as it is, and may be conveyed to a dry zone subsequently in order to adjust the amount of contact gas molecules remaining in the film. When conveying to a drying zone, the method of making hot air or a warm air, or a low gas concentration wind, match with the cellulose acylate film conveyed by a roll group and the cellulose acylate film conveyed while being clipped by a tenter, and a hot wire Although there is a method of irradiating a film, a method of bringing the heated sheet into contact with a heated roll, and the like, a method of fitting a hot air or a warm air or a wind having a low gas concentration is preferable.

(8) Coiling

The winding machine generally used can be used for the winding machine which winds up the obtained film, and can be wound up by the winding methods, such as the forward tension method, the constant torque method, the taper tension method, and the program tension control method with constant internal stress. In the optical film roll obtained as mentioned above, it is preferable that the slow-axis direction of a film is +/- 2 degree with respect to a winding direction (the longitudinal direction of a film), and it is preferable that it is the range of +/- 1 degree. Or it is preferable that it is +/- 2 degree with respect to the direction orthogonal to the winding direction (width direction of a film), or it is preferable to exist in the range of +/- 1 degree. It is preferable that especially the slow-axis direction of a film is within +/- 0.1 degree with respect to the winding direction (the longitudinal direction of a film). Or it is preferable that it is within +/- 0.1 degree with respect to the width direction of a film.

It is preferable to wind up the length of the film obtained as mentioned above at 100-10000m per roll, More preferably, it is 500-7000m, More preferably, it is 1000-6000m. 0.5-5.0 m are preferable, as for the width | variety of a film, More preferably, it is 1.0-3.0 m, More preferably, it is 1.0-2.5 m. At the time of winding, it is preferable to give a knurling to at least one end, The width of a knurling is preferable 3 mm-50 mm, More preferably, 5 mm-30 mm, The height is 0.5-500 micrometers, More preferably, 1-200 micrometers. This may be a partial pressure or a positive pressure.

The film of the present invention is particularly suitable for use in a large screen liquid crystal display device. When using as an optical compensation film for big screen liquid crystal display devices, it is preferable to shape | mold and shape a film width to 1470 mm or more, for example. Moreover, in the optical compensation film of this invention, not only the film of the aspect of the film piece cut | disconnected in the size which can be attached to a liquid crystal display device as it is, but the film of the aspect produced by the continuous production in the form of a long picture and wound up in roll shape Also included. The optical compensation film of the latter aspect is cut | disconnected to a desired magnitude | size and used when it is actually attached to a liquid crystal display device, or is bonded together with a polarizer etc., etc. stored and conveyed in that state. Moreover, after bonding together with the polarizer which consists of a polyvinyl alcohol film etc. produced in the elongate shape etc. in the elongate shape similarly, it is cut | disconnected to a desired size and used when actually attaching to a liquid crystal display device. As an aspect of the optical compensation film wound up in roll shape, the aspect wound up to the roll shape whose roll length is 2500 m or more is mentioned.

The web thus obtained can be wound up to obtain a cellulose acylate film as a final finished product.

In the manufacturing method of the said cellulose acylate film, it is preferable to manufacture so that it may become a range of the preferable film thickness of the said cellulose acylate film from a viewpoint of manufacture cost and optical characteristic expression.

The film thickness can be adjusted by adjusting the solid content concentration contained in the dope, the slit gap of the die mold, the extrusion pressure from the die, the metal support speed, and the like so as to have a desired thickness.

<Polarizer>

Although the cellulose acylate film of this invention functions as a retardation film, It is preferable to attach as a protective film of a polarizing plate preferably.

That is, the polarizing plate of this invention contains a polarizer and at least one cellulose acylate film of this invention on at least one side of this polarizer. Hereinafter, the polarizing plate of the present invention will be described.

In the same manner as the film of the present invention, the aspect of the polarizing plate of the present invention is produced in a long shape by continuous production, as well as the polarizing plate of the aspect of the film piece cut into a size that can be directly attached to a liquid crystal display device, in a roll shape. The polarizing plate of the wound up aspect (for example, aspect of 2500 m or more of roll length or 3900 m or more) is also included. In order to use for a big screen liquid crystal display device, as above-mentioned, it is preferable that the width of a polarizing plate shall be 1470 mm or more.

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 this invention, although at least one side of a polarizing plate protective film contains the cellulose acylate film of this invention, a well-known cellulose acylate film can be used as another polarizing plate protective film. It is preferable that it is 10-40 micrometers, and, as for the thickness of the other polarizing plate protective film, it is more preferable that it is 20-40 micrometers.

Moreover, it is preferable that the total thickness of the polarizing plate of this invention is 40-100 micrometers, It is more preferable that it is 50-100 micrometers, It is especially preferable that it is 65-95 micrometers. The total thickness here is in addition to the polarizer and the polarizing plate protective film bonded to the both sides of this polarizer, and is the meaning containing the adhesive bond layer which bonds this polarizing plate protective film.

There is no restriction | limiting in particular about the specific structure of the polarizing plate of this invention, A well-known structure can be employ | adopted, For example, the structure of FIG. 6 of Unexamined-Japanese-Patent No. 2008-262161 can be employ | adopted.

<Liquid Crystal Display Device>

The liquid crystal display device of the present invention includes at least one polarizing plate of the present invention. The liquid crystal display of this invention includes the polarizing plate of this invention containing the cellulose acylate film of this invention, and the contrast of the front direction and the color change of the viewing angle direction are remarkably improved.

In the liquid crystal display device of the present invention, the thickness of the glass constituting the liquid crystal cell is preferably 50 to 500 mu m. By using such a 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, wherein the polarizer is an IPS, OCB or VA mode. It is preferable that it is a liquid crystal display device of.

There is no restriction | limiting in particular as a specific structure of the liquid crystal display device of this invention, A well-known structure can be employ | adopted, For example, the example made into the structure of FIG. 1 can be employ | adopted. The configuration described in FIG. 2 of Japanese Laid-Open Patent Publication No. 2008-262161 is also preferably employed.

Example

Hereinafter, the present invention will be described in more detail with reference to examples. The materials, the amounts to be used, the ratios, the contents of the treatments, the processing procedures, and the like shown in the following examples can be appropriately changed as long as they do not depart from the gist of the present invention. Therefore, the scope of the present invention is not limited to the following specific examples.

In this invention, the film characteristic was measured by the following measuring method.

(Optical characteristics)

Re and Rth were measured with the wavelength of 590 nm by KOBRA 21ADH (Oji Measurement Instruments Co., Ltd. product) by said method.

(Internal haze)

Glycerine drops are dropped on both surfaces of the obtained cellulose acylate film sample 40 mm x 80 mm, and the glass plate of 1.3 mm thickness (manufactured by MICRO SLIDE GLASS part no. In%, the value (%) which subtracted the haze measured in the state which dripped the glycerin several drops between glass 2 from the haze value measured according to JISK-6714 by the haze meter (HGM-2DP, Suga tester) inside Haze was taken. The results are shown in the table below.

(Production of cellulose acylate film)

(1) dope preparation

The following composition was put into a mixing tank, stirred to dissolve each component, and heated at 90 ° C. for about 10 minutes, and then filtered through a filter paper having an average pore diameter of 34 μm and a sintered metal filter having an average pore diameter of 10 μm.

-------------------------------

Cellulose acylate solution

-------------------------------

100.0 mass parts of total cellulose acylate shown in the following table

Additives described below 3 Units described in the table below: parts by mass

Additive B as described below Units shown in the table below: parts by mass

KV 37 (Peeling accelerator) Quantity unit shown in the table below: parts by mass

Methylene chloride 403.0 parts by mass

60.2 parts by mass of methanol

―――――――――――――― ――――――――――――――――

Additive A reacts AA (adipic acid) with EG (ethylene glycol), and the terminal was sealed with OAc (Ac is an acetyl group).

Additive B is a compound in which TPA (terephthalic acid), SA (succinic acid), EG (ethylene glycol), and PG (1,2-propylene glycol) were reacted and the terminal was sealed with Ac.

Additive 2:

It synthesize | combined according to description of Unexamined-Japanese-Patent No. 2012-31313.

Additive 3:

Additive 4 (ester oligomer) was synthesize | combined as follows.

PG and TPA were reacted to the following composition, and an oligomer mixture was prepared. After stirring, mBA was dripped and the prepared oligomer was sealed.

mBA- (PG-TPA) n-PG-mBA: n is 0-2 here.

mBA represents methyl benzoate, PG represents propylene glycol, TPA represents terephthalic acid and BA represents benzoate, respectively.

Peeling promoter: K-37V (Poem K-37V, manufactured by Riken Vitamin Co., Ltd.)

<1-2> Matte Dispersion

Next, the following composition containing the cellulose acylate solution produced by the above method was added to a disperser to prepare a dispersion of a mat agent.

-------------------------------

Matte dispersion

-------------------------------

0.2 parts by mass of matting agent (Aerosil R972)

Methylene chloride 72.4 parts by mass

10.8 parts by mass of methanol

10.3 parts by mass of cellulose acylate solution

-------------------------------

100 mass parts of the said cellulose acylate solution and the dispersion liquid made into the mat | matte dispersion were mixed with the quantity which an inorganic fine particle becomes 0.02 mass part with respect to a cellulose acylate resin, and the dope for film forming was prepared.

(2) flexible

The above-mentioned dope was cast using a band softener. In addition, the band was made of SUS.

(3) Drying

The web (film) obtained by casting | flow_spread was dried for 20 minutes in the tenter apparatus using the tenter apparatus which clips and conveys both ends of a web with a clip after peeling from a band. In addition, the drying temperature here means the film surface temperature of a film.

(4) stretching

The obtained web (film) was peeled off from the band, sandwiched in a clip, and tentered at the stretching temperature and the stretching ratio shown in the following table under the conditions of fixed end uniaxial stretching when the amount of residual solvent relative to the mass of the entire film was 30 mass%. It extended | stretched in the direction (horizontal direction) orthogonal to a film conveyance direction using the process. At this time, the casting film thickness was adjusted so that the film thickness after extending | stretching might become the film thickness (unit: micrometer) shown in a table | surface.

(5) immersion method

The stretched film was immersed in a water bath at the temperature and time shown in the following table. Both were immersed so that the elongation rate in the conveyance direction of a film might be 1% or less. After immersion, water droplets on the surface of the film were removed and dried by warm air at 100 ° C.

Then, after cooling to room temperature, the film was wound up and the roll of 1280 mm in roll width and 2600 mm in roll length was produced at least 24 rolls on the said conditions in order to judge the manufacturing suitability. The sample (width 1280 mm) of length 1m was cut out at 100 m space with respect to 1 roll in 24 rolls continuously manufactured.

Cellulose acylate films 2 to 11 were produced in the same manner as described above, except that the degree of substitution of the cellulose acylate, the dope solution constitution, and the manufacturing conditions were changed as shown in the following table.

(Measurement of equilibrium moisture content)

The equilibrium moisture content was measured by Karl Fischer method as follows.

(1) A sample (two sheets of 0.9 m x 4.5 cm) was weighed. If the sample was wet, the surface moisture was quickly wiped off. Immediately after sampling, it was immediately ground to a stoppered glass bottle and transported to a water meter, and measured within 3 minutes after sampling.

(2) It measured using the following moisture meter.

Vaporizer: Using the Mitsubishi Chemical Corporation VA-05 type, the water in the sample was volatilized at 150 ° C and introduced into the moisture system.

-Moisture meter: It measured using the Karl Fischer moisture meter (the Mitsubishi Chemical Corporation CA-03 type).

(3) The moisture content (μg) indicated by the moisture meter was W, and the sample amount weighed was F (mg), and the equilibrium moisture content was calculated from the following equation.

Equilibrium moisture content (%) = 100 × (W / 1000 F) = 0.1 × (W / F)

(Equilibrium moisture content change before and after immersion (ΔM))

The obtained film was cut out in 10 cm x 10 cm, and it was immersed in 40 degreeC pure water for 24 hours. Then, the surface water was wiped off, it was dried for 5 minutes by the warm air of 100 degreeC, it was humidified for 24 hours at 25 degreeC80% relative humidity, and the film equilibrium moisture content was measured by the said Karl Fischer method. Moreover, the equilibrium moisture content at 25 degreeC 80% after water immersion and the equilibrium moisture content at 25 degreeC 80% before water immersion were compared, and the change of equilibrium moisture content was computed.

(Production of Polarizing Plate Sample)

The alkali saponification process of the surface of the cellulose acylate film of each Example and comparative example produced above was carried out. It was immersed in 1.5 sodium hydroxide aqueous solution at 55 degreeC for 2 minutes, it wash | cleaned in the water washing bath at room temperature, and it neutralized using 0.1 sulfuric acid at 30 degreeC. Again, it was washed in a washing bath at room temperature and further dried by hot air at 100 ° C.

Subsequently, the rolled polyvinyl alcohol film was continuously stretched 5 times in an aqueous solution of iodine and dried to obtain a polarizer. The polyvinyl alcohol (Kuraray Co., Ltd. PVA-117H) 3% aqueous solution was used as an adhesive agent, the 1st polarizing plate protective film and the 2nd polarizing plate protective film of each Example and comparative example which were treated with said alkali saponification were prepared, and these saponified surfaces The polarizer was sandwiched and bonded together so that it might become this polarizer side, and the polarizing plate which the 1st polarizing plate protective film, the polarizer, and the 2nd polarizing plate protective film of each Example and the comparative example were bonded in this order, respectively was obtained. At this time, it stuck so that MD direction of a 1st polarizing plate protective film and a 2nd polarizing plate protective film might become parallel to the absorption axis of a polarizer.

The film of Comparative Example 3 could not be peeled from the support.

(Fabrication of liquid crystal display device)

The polarizing plate and retardation plate of the front and back of the liquid crystal TV (LC-46LV3, the product made by SHARP) of VA mode were peeled, and it used as a liquid crystal cell. Like the structure of FIG. 1 (upper front side), the outer protective film (not shown), the polarizer 11, the film 14 (rear cellulose acylate film of a rear side) of each Example and comparative example shown in the following table, The liquid crystal cell 13 (the above VA liquid crystal cell), the film 15 (the cellulose acylate film on the front side), the polarizer 12, and the outer protective film (not shown) of each of the Examples and Comparative Examples described in the following table. It bonded together using an adhesive in this order, and produced the liquid crystal display devices 1-11 of each Example and the comparative example. At this time, the absorption axes of the upper and lower polarizing plates were orthogonalized.

(Front Contrast Evaluation)

Using the measuring device (BM5A, TOPCON Co., Ltd.), the luminance values of the black display and the white display in the panel front direction were measured in the dark room, and the front contrast (white luminance / black luminance) was calculated.

The observed contrast was evaluated according to the following criteria.

A: more than 6500

B: 5000 or more but less than 6500

C: less than 5000

(Evaluation standard of light leakage)

About the produced liquid crystal display device, the light leakage in the inclination direction at the time of black display in a dark room, and the sensory evaluation of color shift were performed, and the following references | standards evaluated.

A: Light leakage is hardly observed in all polar and azimuth directions.

B: Light leakage is observed slightly in the region where the polar angle is larger than 60 degrees.

C: Even in the area | region where polar angle is smaller than 60 degree | times, light leakage is observed slightly.

(Condensation nonuniformity evaluation)

500 µL of pure water was added dropwise to the surface of the viewer-side polarizing plate of the produced liquid crystal display, and Saran Lab (registered by Asahi Kasei Home Products Co., Ltd.) was cut 10 cm × 10 cm, and four sides were fixed with tape. . The liquid crystal display device was turned on continuously for 24 hours, the saran wrap was removed, and the water droplets of the surface were wiped off. Then, after lighting a liquid crystal display device continuously for 24 hours, the nonuniformity at the time of black display was evaluated from the front and inclination directions.

[Front nonuniformity]

A: Not admitted at all

B: weakly acknowledged

C: strongly admitted

[Tilt Unevenness]

A: Not admitted at all

B: weakly acknowledged

C: strongly admitted

From the table, it turned out that the liquid crystal display device using the liquid crystal display devices 1-8 using the cellulose acylate film of this invention is excellent in front contrast, the light leakage of the diagonal direction, and condensation nonuniformity. On the other hand, it turned out that any of liquid crystal display devices 9-11 using the film of the comparative example was inferior to front contrast, the light leakage of the diagonal direction, and condensation nonuniformity.

11: polarizer
12: polarizer
13: liquid crystal cell
14: cellulose acylate film of each Example and Comparative Example
15: Cellulose acylate film of each Example and Comparative Example

Claims (12)

The cellulose acylate film whose film thickness is 20-60 micrometers, contains the cellulose acylate and additive of total acyl substitution degree 2.0-2.55, and satisfy | fills following formula (I)-(IV).
Formula (I) 30 nm ≤ Re (590) ≤ 90 nm
Formula (II) 100 nm ≤ Rth (590) ≤ 150 nm
Equation (III) 2.0 ≤ Rth (590) / d ≤ 5.0
Equation (IV) Internal haze ≤ 0.05%
Formula (V) ΔM ≤ 1.0%
(Wherein Re (590) represents the retardation (nm) in the in-plane direction at the wavelength 590 nm, Rth (590) represents the retardation (nm) in the film thickness direction at the wavelength 590 nm, and d is ΔM is the equilibrium moisture content at 25 ° C. 80% by the Karl Fischer method after immersing the cellulose acylate film in 40 ° C. pure water for 24 hours, and 25 ° C. 80 by the Karl Fischer method before immersion. The difference in equilibrium moisture content in% is shown.) The method according to claim 1,
The cellulose acylate film in which the said additive contains the compound containing an aromatic. 3. The method of claim 2,
The cellulose acylate film containing at least 1 sort (s) chosen from a sugar ester compound, a nitrogen-containing ring compound, and ester type polymer as said compound containing an aromatic. The method according to claim 1,
The film thickness is 30-50 micrometers, the total acyl substitution degree is 2.4-2.55, Re (590) is 40-90 nm, Rth (590) is 110-130 nm, internal haze is 0.03% or less, (DELTA) M The cellulose acylate film which is 0.5% or less. 3. The method of claim 2,
The film thickness is 30-50 micrometers, the total acyl substitution degree is 2.4-2.55, Re (590) is 40-90 nm, Rth (590) is 110-130 nm, internal haze is 0.03% or less, (DELTA) M It is 0.5% or less and a cellulose acylate film containing at least 1 sort (s) chosen from a sugar ester compound, a nitrogen-containing ring compound, and an ester polymer as a compound containing the said aromatic. Forming a polymer solution having a cellulose acylate having a total substitution degree of 2.0 to 2.55, a solvent and an additive in the form of a film, and controlling the stretching so that the film thickness becomes 20 to 60 µm after stretching the film. And further comprising a step of water treatment of the stretched film. The method according to claim 6,
The process of water treatment is a process of immersing cellulose acylate in water of 25-85 degreeC for 5 second or more, and also including adjusting so that the film elongation rate of the conveyance direction at the time of the said water treatment may be 1% or less. The manufacturing method of the cellulose acylate film characterized by the above-mentioned. The method according to claim 6,
The manufacturing method of the cellulose acylate film whose said cellulose acylate film is a cellulose acylate film of Claim 1. The polarizing plate containing a polarizer and the cellulose acylate film of Claim 1. The method of claim 9,
The said polarizing plate has a protective film also in the surface on the opposite side to the said cellulose acylate film, The said protective film is a cellulose acylate film whose film thickness is 20-60 micrometers, The polarizing plate characterized by the above-mentioned. The liquid crystal display device which has a polarizing plate of Claim 9. The method of claim 11,
The liquid crystal display device in which the said liquid crystal display device has a glass substrate of 50-500 micrometers in thickness.

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