JP5926665B2 - Cellulose acylate film, polarizing plate and liquid crystal display device - Google Patents

Description

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

  In recent years, TV applications of liquid crystal display devices have progressed, and there has been an increasing demand for higher image quality and lower price as the screen size increases. A liquid crystal display device incorporates a polarizing plate, and a cellulose acylate film is employed as a protective film for such a polarizing plate.

In recent years, there has been an increasing demand for thinning liquid crystal display devices. Therefore, it is beneficial if the polarizing plate, which is a component part of the liquid crystal display device, can be thinned.
As a method of reducing the thickness of the polarizing plate, it is conceivable to thin a film (cellulose acylate film) mainly composed of cellulose acylate used as a protective film for the polarizing plate. Here, in order to develop the predetermined retardation (Rth) while reducing the film thickness of the cellulose acylate film, it is necessary to increase the predetermined value of Rth / d (d is the film thickness) from the conventional value. .

  Here, in the liquid crystal display device for VA, as a method for obtaining necessary Rth, a method using cellulose acetate having a low substitution degree described in Patent Document 1 is described. On the other hand, Patent Document 1 describes a method for increasing the degree of orientation of an additive using an aromatic oligomer.

JP 2009-265598 A JP 2012-67272 A

Here, in order to express a predetermined retardation, the present inventor tried to increase the degree of orientation in the method described in Patent Document 1 described above. However, a film exhibiting an appropriate retardation was not obtained with these two combinations. Further, even a thin film needs to satisfy display characteristics (contrast and light leakage) required for a liquid crystal display device when used as a protective film for a polarizing plate of a liquid crystal display device.
The present invention is intended to solve the problems of the prior art, and is thin and highly expressed while maintaining the performance required when used as a protective film for a polarizing plate of a liquid crystal display device. It aims at providing the cellulose-ester film which has property.

  Under such circumstances, as a result of intensive studies by the present inventor, the above problems can be solved by adjusting the degree of orientation of the cellulose acylate and the degree of orientation of the additive containing an aromatic to satisfy a predetermined relationship. I found that it could be solved. Specifically, the above-mentioned problem has been solved by the following means <1>, preferably <2> to <14>.

<1> Cellulose acylate having a total acyl substitution degree of 2.0 to 2.95 and an additive containing an aromatic, a film thickness of 10 to 45 μm, and an internal haze of 0.10% or less, A cellulose acylate film satisfying the following formulas (1) to (3).
Formula (1) 40 nm <Re (550) <150 nm
Formula (2) 80 nm <Rth (550) <350 nm
Formula (3) 0.70 ≦ P_a / P_p ≦ 2.00
(In the formula, Re (550) represents in-plane retardation at a wavelength of 550 nm, Rth (550) represents retardation in the film thickness direction at a wavelength of 550 nm, P_p represents the degree of orientation of cellulose acylate, and P_a contains aromatics. Represents the degree of orientation of the additive.
<2> The cellulose acylate film according to <1>, wherein the degree of orientation P_p of the cellulose acylate satisfies the following formula (3 ′).
Formula (3 ′) P_p ≦ 0.15
<3> The cellulose acylate film according to <1> or <2>, wherein Nz represented by the following formula of the cellulose acylate film is 1.1 to 4.5.
Nz = Rth (550) / Re (550) +0.5
<4> The cellulose acylate film according to any one of <1> to <3>, wherein the degree of substitution of the cellulose acylate is 2.0 to 2.6.
<5> The cellulose reed according to any one of <1> to <4>, wherein the additive containing an aromatic is a polycondensed ester containing an aromatic and / or a sugar ester containing an aromatic. Rate film.
<6> Any one of <1> to <5>, wherein the dimensional change rate after the cellulose acylate film is treated at 60 ° C. and a relative humidity of 90% for 24 hours satisfies the following formulas (4) and (5): The cellulose acylate film described in 1.
Formula (4) ΔL (MD) / L (MD)> 0.10%
Expression (5) ΔL (TD) / L (TD)> 0.30%
(Where L (MD) and L (TD) represent the longitudinal and lateral dimensions, respectively, before treatment for 24 hours at 60 ° C. and 90% relative humidity, ΔL (MD) and ΔL (TD) Represents the amount of dimensional change in the vertical and horizontal directions after treatment for 24 hours at 60 ° C. and 90% relative humidity, respectively.
<7> The cellulose acylate film according to any one of <1> to <6>, wherein the cellulose acylate film satisfies ΔRe (550) <− 5 nm and ΔRth (550) <− 5 nm;
ΔRe (550) is (retardation in the in-plane direction at a wavelength of 550 nm of the cellulose acylate film after being treated at 60 ° C. and 90% relative humidity for 24 hours) − (treated at 60 ° C. and 90% relative humidity for 24 hours) In-plane direction retardation at a wavelength of 550 nm of the previous cellulose acylate film);
ΔRth (550) is (retardation in the thickness direction at a wavelength of 550 nm of a cellulose acylate film after being treated at 60 ° C. and 90% relative humidity for 24 hours) − (treated at 60 ° C. and 90% relative humidity for 24 hours) Retardation in the thickness direction at a wavelength of 550 nm of the previous cellulose acylate film).
<8> The difference between the equilibrium moisture content by Karl Fischer method after immersion for 24 hours in pure water at 40 ° C. and the equilibrium moisture content by Karl Fischer method before immersion is less than 1.0%. The cellulose acylate film according to any one of <1> to <7>.
<9> An optical film having a retardation layer in which an alignment state of the cellulose acylate film and the liquid crystal material according to any one of <1> to <8> is fixed,
The retardation layer contains a liquid crystal compound that is homeotropically aligned,
An optical film in which the optical characteristics of the retardation layer satisfy the following formulas (1), (2), and (3).
80 ≦ Re ≦ 150 Formula (1)
−100 ≦ Rth ≦ 10 Formula (2)
0.05 ≦ | Rth / Re | ≦ 1.0 Formula (3)
<10> The optical film according to <9>, having an intermediate layer containing a polyvinyl alcohol resin and / or an acrylic resin having a polar group between the cellulose acylate film and the retardation layer.
<11> A step of forming a polymer solution containing a cellulose acylate having a total acyl substitution degree of 2.0 to 2.95 as a main component and an additive containing an aromatic, and a step of stretching the film A method for producing a cellulose acylate film comprising the steps of immersing in an organic solvent containing 20% by mass or more of methanol and further drying the solvent in a state where the residual solvent in the film is 5% by mass or less.
<12> The method for producing a cellulose acylate film according to <11>, wherein the organic solvent contains dichloromethane.
<13> A polarizer and a polarizing plate having the cellulose acylate film according to any one of <1> to <9> or the optical film according to <10> or <11> on at least one side of the polarizer.
<14> A liquid crystal display device having the polarizing plate according to <13>.

 According to the present invention, it has become possible to provide a cellulose ester film that is thin and has high expression. Further, when the cellulose ester film of the present invention is used as a polarizing plate protective film for a liquid crystal display device, a liquid crystal display device having excellent contrast and no light leakage can be provided.

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

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

<Cellulose ester film>
The cellulose ester film of the present invention (hereinafter sometimes referred to as “the film of the present invention”) includes a cellulose acylate having a substitution degree of 2.0 to 2.95 and an additive containing an aromatic, and has a film thickness. It is 10-45 micrometers, an internal haze is 0.10% or less, and satisfy | fills following formula (1)-(3), It is characterized by the above-mentioned.
Formula (1) 40 nm <Re (550) <150 nm
Formula (2) 80 nm <Rth (550) <350 nm
Formula (3) 0.70 ≦ P_a / P_p ≦ 2.00
(In the formula, Re (550) represents in-plane retardation at a wavelength of 550 nm, Rth (550) represents retardation in the film thickness direction at a wavelength of 550 nm, P_p represents the degree of orientation of cellulose acylate, and P_a contains aromatics. Represents the degree of orientation of the additive.

In order to produce such a thin film satisfying the formulas (1) and (2), the present invention includes a cellulose acylate having a substitution degree of 2.0 to 2.95 and an additive containing an aromatic. The degree of orientation of the cellulose acylate and the degree of orientation of the aromatic-containing additive are adjusted so as to satisfy the relationship of formula (3).
The degree of orientation of cellulose acylate can be adjusted by stretching conditions as described later. At that time, the degree of orientation of the additive also changes due to stretching, but it does not completely follow the orientation of cellulose acylate. Therefore, independent adjustment is required to adjust the relationship to satisfy the relationship of formula (3).
Such an orientation degree is achieved, for example, by immersing the stretched film in methanol. When immersed in methanol, the additive containing aromatics moves in the film, and the degree of orientation of the additive containing aromatics improves. On the other hand, the degree of orientation of cellulose acylate does not change even when immersed in methanol. Therefore, a film satisfying the above formula (2) can be produced as a thin film.
The degree of orientation in the present invention is a value measured by a method for measuring the degree of orientation defined in the examples described later.

As described above, in order to realize the optical expression required for the VA mode and the IPS mode with a thin film, it is necessary to increase the degree of orientation of the polymer and / or the orientation of the additive. However, if the degree of orientation of the polymer is increased too much, the brittleness of the film is deteriorated and the tear strength may be lowered. In order to suppress these more effectively, the orientation degree P_p of the cellulose acylate preferably satisfies the following formula (3 ′), more preferably is 0.14 or less, and further preferably is 0.13 or less.
Formula (3 ′) P_p ≦ 0.15 or less If the degree of orientation of cellulose acylate is 0.15 or less, a film having better tear strength and better handling properties can be obtained.

 Further, as a result of investigation by the present inventors, when a compound having liquid crystallinity is used as an additive, the degree of orientation of the additive becomes higher than the degree of orientation of cellulose acylate, but the additives tend to aggregate with each other and internal haze is likely to occur. It has also been found that there is a problem that the front contrast is lowered when the liquid crystal display device is incorporated into a liquid crystal display device.

According to this invention, the film which has high optical expression property can be provided by making orientation degree P_a / P_p of an additive into the range of 0.70-2.00. Furthermore, it can be set as a film with a low low internal haze. In addition, high front contrast and low viewing angle light leakage can be realized when incorporated in a liquid crystal display device.
Hereinafter, the details of the film of the present invention will be described. Needless to say, the present invention is not limited to these examples.

<Cellulose acylate>
The cellulose acylate film of the present invention contains cellulose acylate as a main component of the polymer component. The cellulose acylate used in the present invention is not particularly limited as long as it is a cellulose acylate having a total acyl substitution degree of 2.0 to 2.95, and a known cellulose acylate can be used.

  Cellulose acylate raw material cellulose used in the present invention includes cotton linter and wood pulp (hardwood pulp, conifer pulp), and any cellulose acylate obtained from any raw material cellulose can be used. May be used. Detailed descriptions of these raw material celluloses can be found in, for example, Marusawa and Uda, “Plastic Materials Course (17) Fibrous Resin”, published by Nikkan Kogyo Shimbun (published in 1970), and the Japan Society of Invention and Innovation Technical Bulletin No. 2001. The cellulose described in No.-1745 (pages 7 to 8) can be used, and is not particularly limited to the cellulose acylate laminated film of the present invention.

  First, the cellulose acylate preferably used in the present invention will be described in detail. Glucose units having β-1,4 bonds constituting cellulose have free hydroxyl groups at the 2nd, 3rd and 6th positions. Cellulose acylate is a polymer obtained by acylating part or all of these hydroxyl groups with an acyl group. The degree of acyl substitution means the sum of the ratios of acylation of the hydroxyl groups of cellulose located at the 2-position, 3-position and 6-position (100% acylation at each position is substitution degree 1).

Only one type of acyl group may be used in the cellulose acylate of the present invention, or two or more types of acyl groups may be used.
The acyl group of cellulose acylate in the present invention may be an aliphatic group or an allyl group and is not particularly limited. These are, for example, cellulose alkylcarbonyl esters, alkenylcarbonyl esters, aromatic carbonyl esters, aromatic alkylcarbonyl esters, and the like, each of which may further have a substituted group. Preferred examples of these are acetyl group, propionyl group, butanoyl group, heptanoyl group, hexanoyl group, octanoyl group, decanoyl group, dodecanoyl group, tridecanoyl group, tetradecanoyl group, hexadecanoyl group, octadecanoyl group, isobutanoyl group. Group, tert-butanoyl group, cyclohexanecarbonyl group, oleoyl group, benzoyl group, naphthylcarbonyl group, cinnamoyl group and the like. Among these, an acetyl group, a propionyl group, a butanoyl group, a dodecanoyl group, an octadecanoyl group, a tert-butanoyl group, an oleoyl group, a benzoyl group, a naphthylcarbonyl group, a cinnamoyl group, and the like are more preferable, and an acetyl group is particularly preferable. A propionyl group and a butanoyl group (when the acyl group has 2 to 4 carbon atoms), more preferably an acetyl group (when the cellulose acylate is cellulose acetate).

  That is, examples of the cellulose acylate include triacetyl cellulose (TAC), diacetyl cellulose (DAC), cellulose acetate propionate (CAP), cellulose acetate butyrate (CAB), and cellulose acetate phthalate. In the cellulose acylate film of the present invention, it is preferable from the viewpoint of retardation development and cost that all the acyl groups of the cellulose acylate are acetyl groups.

The film of the present invention contains cellulose acylate having a total acyl substitution degree of 2.0 to 2.95. From the viewpoint of increasing the intrinsic birefringence of the cellulose acylate, the total acyl substitution degree of the cellulose acylate preferably satisfies 2.0 to 2.6, and more preferably 2.2 to 2.5.
In addition, the substitution degree of an acyl group can be measured according to the method prescribed | regulated to ASTM-D817-96. The portion not substituted with an acyl group usually exists as a hydroxyl group.

  In a preferred embodiment of the present invention, even in a cellulose acylate film containing a cellulose acylate having a low acyl substitution degree, the retardation change under wet heat conditions is improved, and chromatic dispersion is converted to reverse wavelength dispersion (ΔRe is positive). Improvement can be improved at the same time, and a cellulose acylate film containing cellulose acylate having a low acyl substitution degree can be produced.

  These cellulose acylates can be synthesized by a known method, for example, by the method described in JP-A-10-45804.

In the acylation of cellulose, when an acid anhydride or acid chloride is used as an acylating agent, an organic acid such as acetic acid or dichloromethane is used as an organic solvent as 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), Basic compounds are used.

  The most common industrial synthesis method of cellulose mixed fatty acid ester is to use cellulose corresponding to fatty acid corresponding to acetyl group and other acyl groups (acetic acid, propionic acid, valeric acid, etc.) or their anhydrides. This is a method of acylating with a mixed organic acid component.

The cellulose acylate preferably has a number average molecular weight (Mn) of 40,000 to 200,000, more preferably 100,000 to 200,000. The cellulose acylate used in the present invention preferably has an Mw / Mn ratio of 4.0 or less, more preferably 1.4 to 2.3.
In the present invention, the average molecular weight and molecular weight distribution of cellulose acylate, etc. are calculated by calculating the number average molecular weight (Mn) and the weight average molecular weight (Mw) using gel permeation chromatography (GPC). International Publication WO 2008-126535 The ratio can be calculated by the method described in the publication.

  In the film of the present invention, the content of the cellulose acylate in the film is preferably 85% by mass or more, more preferably more than 85% by mass, and 86% by mass or more with respect to the mass of the film. It is particularly preferred. Moreover, the cellulose acylate content in the film can be decreased as the total substitution degree of cellulose acylate is higher, and the cellulose acylate content in the film can be increased as the total substitution degree is lower.

The degree of orientation P_p of cellulose acylate can be adjusted by stretching conditions such as the stretching ratio.
The degree of orientation P_p of the cellulose acylate used in the present invention is preferably 0.15 or less, and more preferably 0.09 or less.

  Cellulose acylate is formed of a main chain composed of a glucopyranose ring and a side chain composed of an acyl group. When a film made of cellulose acylate is stretched, the optical anisotropy is expressed by the polymer main chain being oriented in the stretching direction.

<Additives containing aromatics>
The cellulose acylate film of the present invention uses an aromatic-containing additive in order to obtain high optical expression when the degree of orientation of the additive is increased. As the additive containing an aromatic group, a polycondensed ester and / or a sugar ester is preferable.
It is preferable that the total compounding quantity of the additive containing the aromatic in this invention is 3-40 mass% with respect to 100 mass parts of cellulose acylates. By setting it as such a range, the effect of this invention is exhibited more effectively.

<Polycondensed ester>
A polycondensation ester containing an aromatic can be contained as an additive containing an aromatic. When such a polycondensation ester is added, the expression of retardation is enhanced, and even if moisture penetrates into the film, it is difficult for it to move through the film, so that the change in retardation before and after water treatment can be reduced. it can.

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

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

  The polycondensed ester contains a dicarboxylic acid residue and a diol residue, but must have an aromatic group in either the dicarboxylic acid residue or the diol residue.

In the polycondensed ester, an aromatic dicarboxylic acid residue and an aliphatic dicarboxylic acid residue can be used as the dicarboxylic acid residue.
The polycondensation ester used in the present invention preferably contains at least one 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 polycondensation ester used for this invention is 50 mol% or more.
By setting the aromatic dicarboxylic acid residue ratio to 50 mol% or more, a cellulose acylate film can be obtained that exhibits sufficient optical expression even when the film thickness is small (particularly, the value of Rth per film thickness is large). There is a tendency.

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

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

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

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

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

In the polycondensed ester, an aromatic diol residue and an aliphatic diol residue can be used as the diol residue.
The polycondensed ester used in the present invention contains at least one aliphatic diol residue as a diol residue.

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

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

Examples of the aliphatic diol residue having 3 or more carbon atoms include 1,2-propanediol residue, 1,3-propanediol residue, 1,2-butanediol residue, 1,3-butanediol residue, 2-methyl-1,3-propanediol residue, 1,4-butanediol residue, 1,5-pentanediol residue, 2,2-dimethyl-1,3-propanediol (neopentyl glycol) residue, Examples include 1,4-hexanediol residue, 1,4-cyclohexanediol residue and the like. Among them, the aliphatic diol residue having 3 or more carbon atoms preferably used in the present invention includes 1,2-propanediol residue, 1,3-propanediol residue, 1,2-butanediol residue, 1, 3-butanediol residue, 2-methyl-1,3-propanediol residue, 1,4-butanediol residue, 1,5-pentanediol residue, 2,2-dimethyl1,3-propanediol ( Neopentyl glycol) residue, more preferably 1,2-propanediol residue, 1,3-propanediol residue residue, 1,2-butanediol, 1,3-butanediol residue. Group, 2-methyl-1,3-propanediol residue, 1,4-butanediol residue, particularly preferably 1,2-propanediol residue.
By using a 1,2-propanediol residue or a 1,3-propanediol residue, crystallization of the polycondensed ester can be prevented.

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

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

The polycondensed ester may contain only one type of aliphatic diol residue or two or more types. When two types of aliphatic diol residues are included in the polycondensed ester, it is preferable that 1,2-propanediol residues and ethylene glycol residues are included.
In the polycondensed ester, an aromatic diol acid residue is formed from the aromatic diol used for mixing.

Even if the terminal of the polycondensed ester is not sealed and remains a —OH group derived from a diol or a —COOH group derived from a dicarboxylic acid, it reacts with a monocarboxylic acid or a monoalcohol to cause so-called terminal sealing. -O—C (═O) —R ¹ group, —C (═O) —O—R ² group and —O—R ³ group (provided that R ^{1 to} R ³ are each independently Represents an aliphatic group).

  When both ends of the polycondensed ester are unsealed, it is preferable from the viewpoint of inhibiting hydrolysis of the ester group that both ends are —OH groups than both ends are —COOH. That is, when both ends of the polycondensed ester are unsealed, the polycondensed ester is preferably a polyester polyol.

When both ends of the polycondensed ester are sealed, both ends are —O—C (═O) —R ¹ group, —C (═O) —O—R ² group or —O—R ³ group. It is preferable that More preferably, both ends are —O—C (═O) —R ¹ groups, that is, both ends of the polycondensed ester are more preferably sealed by reacting with an aliphatic monocarboxylic acid. .
At this time, both ends of the polycondensed ester are aliphatic monocarboxylic acid residues.

Here, said R < ¹ > -R < ³ > represents an aliphatic group each independently. The aliphatic group represented by R ^{1 to} R ³ may be saturated or unsaturated as long as the aliphatic group does not contain an aromatic ring. The aliphatic group represented by R ^{1 to} R ³ may be either a chain aliphatic group or a cyclic aliphatic group (for example, a cycloalkyl group), and a chain aliphatic group. If it is, it may be linear or branched. The aliphatic group represented by R ^{1 to} R ³ may further have a substituent unless it is contrary to the spirit of the present invention, and the substituent is not particularly limited as long as it does not contain an aromatic ring. An aliphatic group having no substituent is preferred. Moreover, it is preferable that carbon number of the aliphatic group which said R < ¹ > -R < ³ > represents is 1-21, It is more preferable that it is 1-5, It is especially preferable that it is 1-3, 1 or 2 More preferably, it is more preferably 1.
Among them, the aliphatic group represented by R ^{1 to} R ³ is preferably a chain saturated aliphatic group, more preferably a chain alkyl group, and particularly preferably a linear alkyl group. .

That is, when both ends of the polycondensed ester are sealed, both ends of the polycondensed ester are preferably acyl groups having 2 to 22 carbon atoms, and are acyl groups having 2 to 6 carbon atoms. More preferably, it is particularly preferably an acyl group having 2 to 4 carbon atoms (that is, an acetyl group, a propionyl group or a butyryl group), and an acyl group having 2 or 3 carbon atoms (that is, an acetyl group or a propionyl group) More preferably, it is more preferably an acyl group having 2 carbon atoms (that is, an acetyl group). The acyl group here includes an aromatic acyl group (a so-called aroyl group) in addition to an aliphatic acyl group, and is preferably an aliphatic acyl group. When the carbon number of the acyl group at both ends of the polycondensed ester is 3 or less, the volatility is lowered, the weight loss due to heating of the polycondensed ester is not increased, and the occurrence of process contamination and surface failure is reduced. Is possible.
In this case, the monocarboxylic acid used for sealing is preferably an aliphatic monocarboxylic acid having 2 to 22 carbon atoms, more preferably an aliphatic monocarboxylic acid having 2 to 6 carbon atoms, and 2 carbon atoms. It is particularly preferably an aliphatic monocarboxylic acid having 4 to 4, more preferably an aliphatic monocarboxylic acid having 2 or 3 carbon atoms, and more preferably an aliphatic monocarboxylic acid residue having 2 carbon atoms. Even more preferable.

On the other hand, when both ends of the polycondensed ester are sealed, both ends of the polycondensed ester may be a —C (═O) —O—R ² group or a —O—R ³ group.
In this case, methanol, ethanol, propanol, isopropanol, butanol, isobutanol and the like are preferable as monoalcohols used for sealing, and methanol is most preferable.

Both ends of the polycondensed ester are each independently an —OH group or —O—C (═O) —R ¹ group (provided that a plurality of R ¹ are present from the viewpoint of controlling compatibility with cellulose acylate). In some cases, each independently represents an aliphatic group). The both ends may be the same group or different groups, but both are preferably the same group from the viewpoint of ease of synthesis.
More preferably, both ends of the polycondensed ester are —OH groups or are sealed with acetic acid or propionic acid.

  Both ends of the polycondensed ester of the present invention are sealed with acetic acid so that both ends become acetyl ester residues (sometimes referred to as acetyl residues). The cellulose acylate film is preferable from the viewpoint that the handling of the cellulose acylate film is improved and the cellulose acylate film excellent in humidity stability and polarizing plate durability can be obtained.

The number average molecular weight of the polycondensed ester is preferably 500 to 2000, more preferably 700 to 1500, and particularly preferably 700 to 1200. The number average molecular weight of the polycondensed ester is preferably 500 or more from the viewpoint of improving optical expression. Moreover, if it is 2000 or less, compatibility with a cellulose acylate will become high and it will become difficult to produce the bleed-out at the time of film forming and a heat-stretching.
The number average molecular weight of the polycondensed ester of the present invention can be measured and evaluated by gel permeation chromatography. Further, in the case of a polyester polyol having an unsealed terminal, it can also be calculated from the amount of hydroxyl group per weight (hereinafter referred to as hydroxyl value). The hydroxyl value is determined by measuring the amount (mg) of potassium hydroxide required for neutralizing excess acetic acid after acetylating the polyester polyol.
The polycondensed ester according to the present invention can be used as a plasticizer.

  In the cellulose acylate film of the present invention, the content of the polycondensed ester with respect to 100 parts by mass of the cellulose acylate is preferably 5 to 25 parts by mass, more preferably 8 to 20% by mass, Most preferably, it is 15 mass%.

The dicarboxylic acid residue, the diol residue, and the type and ratio of each residue contained in the polycondensed ester used in the present invention can be measured by an ordinary method using H-NMR. Usually, deuterated chloroform can be used as a solvent.
The number average molecular weight of the polycondensed ester can be measured by a usual method using GPC (Gel Permeation Chromatography), and polystyrene can be usually used as a standard material.
For measurement of the hydroxyl value of the polycondensed ester, the acetic anhydride method described in Japanese Industrial Standards JIS K3342 (discontinued) can be applied. When the polycondensate is a polyester polyol, the hydroxyl value is preferably 50 to 190, and more preferably 50 to 130.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

<Other additives>
The cellulose acylate film of the present invention may contain an additive other than the aromatic-containing additive. For example, nitrogen-containing aromatic compounds, peeling accelerators, matting agents, and other general additives that can be used for cellulose acylate films can be widely employed. As other additives, compounds described in International Publication WO2008-126535 and Japanese Unexamined Patent Application Publication No. 2010-79239 can be preferably used.
In addition, a polycondensation ester not containing an aromatic and / or a sugar ester not containing an aromatic may be used in combination without departing from the spirit of the present invention.

<Nitrogen-containing aromatic compound>
In the present invention, a nitrogen-containing aromatic compound may be included as another additive. By containing the nitrogen-containing aromatic compound, the retardation value can be expressed. The nitrogen-containing aromatic compound is not particularly limited as long as it contains nitrogen and is an aromatic compound, and examples thereof include those made of a discotic compound. As the discotic compound, a compound having at least two aromatic rings can be preferably used as a retardation developer.

 Since such an additive has an aromatic ring, it can contribute to the value of P_a, which is the degree of orientation of the additive, by causing the additive itself to perform an orientation in addition to developing a retardation value. .

Since the discotic compound is superior to the rod-shaped compound in Rth retardation expression, it is preferably used when a particularly large Rth retardation is required. Two or more retardation developers may be used in combination.
The retardation developer preferably has a maximum absorption in the wavelength region of 250 to 400 nm, and preferably has substantially no absorption in the visible region.

  The discotic compound has any one of pyridine, pyrimidine, triazine, and purine as a mother nucleus, and an alkyl group, alkenyl group, alkynyl group, amino group, amide group (amide bond) at any substitutable position of the mother nucleus. 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 linked via a sulfur atom) Or a heterocyclic group as a substituent. However, the substituent in the mother nucleus of these discotic compounds may be further substituted with another substituent, and the other substituent is not particularly limited. For example, when the mother nucleus is substituted with an amino group, the amino group may be an alkyl group (further, the alkyl groups may be linked to form a ring) or -SO2R '(R' is an optional substituent). May be substituted).

  In the film of the present invention, the content of the discotic compound is preferably less than 7% by mass, more preferably 1 to 5% by mass, and more preferably 1 to 3% by mass with respect to the cellulose acylate. It is particularly preferred that

The film of the present invention may contain a conventionally known so-called retardation enhancer as the discotic compound. By adopting a retardation developer, high retardation expression can be obtained at a low draw ratio. On the other hand, the film of the present invention is produced by the method for producing a cellulose acylate film, which will be described later, and thus has good retardation development properties even when these retardation developing agents are not included.
The retardation developer is not particularly limited, but includes a rod-shaped compound, a compound having a cyclic structure such as a cycloalkane or an aromatic ring, and a retardation among the non-phosphate ester compounds. The compound which shows expression property can be mentioned. As the compound having a cyclic structure, a discotic compound is preferable. As the rod-like compound or discotic compound, a compound having at least two aromatic rings can be preferably used as a retardation developer.
Two or more types of retardation developing agents may be used in combination.
It is preferable that the retardation developer has substantially no absorption in the visible region.

As the retardation developer, for example, compounds described in JP-A-2004-50516, JP-A-2007-86748, and compounds described in JP-A 2010-46834 can be used. The present invention is not limited to these.
Examples of the discotic compound include a compound described in European Patent Application No. 0911656A2, a triazine compound described in Japanese Patent Application Laid-Open No. 2003-344655, and a method described in Japanese Patent Application Laid-Open No. 2008-150592 [0097] to [0108]. The triphenylene compound to be used can also be preferably used.
In addition, compounds described in [0062] to [0081] of JP2012-144627A can also be preferably used.

  The discotic compound can be synthesized by a known method such as a method described in JP-A No. 2003-344655 and a method described in JP-A No. 2005-134484.

  In addition to the aforementioned discotic compound, a rod-shaped compound having a linear molecular structure can also be preferably used. For example, the rod-shaped compounds described in JP 2008-150592 A [0110] to [0127] are preferably used. it can.

  Specific examples of the discotic compound are given below, but the present invention is not limited to the following specific examples.

In addition to the above, the cellulose acylate film used in the present invention may contain additives that can be added to a normal cellulose acylate film.
Examples of these additives include additives having a negative intrinsic birefringence, fine particles, retardation developing agents, antioxidants, thermal deterioration inhibitors, colorants, ultraviolet absorbers, and the like.
About the said other additive, the compound described in international publication WO2008-126535 can be used preferably.

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

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

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

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

Examples of the compound represented by the general formula (II-1) include the following compounds.

(Additive with negative intrinsic birefringence)
The film of the present invention may contain an additive having a negative intrinsic birefringence. The compound having negative intrinsic birefringence that can be used as an additive having negative intrinsic birefringence will be described below.

  The compound having negative intrinsic birefringence means a material exhibiting negative intrinsic birefringence in a specific direction of the film in the cellulose acylate film. In the present specification, the negative intrinsic birefringence refers to a property having a negative birefringence. Whether or not it has negative intrinsic birefringence can be determined, for example, by measuring the birefringence of the film in a system not added with the compound with a birefringence meter and comparing the difference. be able to.

The compound having negative intrinsic birefringence of the present invention is not particularly limited, and a known compound exhibiting negative intrinsic birefringence can be used. For example, JP-A 2010-46834 discloses [0036] to [0036] The compounds disclosed in [0092] can be preferably used.
Examples of the compound having negative intrinsic birefringence include a polymer having negative intrinsic birefringence, and acicular fine particles having negative intrinsic birefringence (including acicular fine particles of a polymer having negative intrinsic birefringence). And so on. Hereinafter, a polymer having negative intrinsic birefringence that can be used in the present invention will be described.

  The polymer having negative intrinsic birefringence means that when light is incident on a layer in which molecules have a uniaxial orientation, the refractive index of light in the orientation direction is perpendicular to the orientation direction. A polymer smaller than the refractive index of light.

As a polymer having such a negative intrinsic birefringence, as a negative polymer, a polymer having a specific cyclic structure (a disc-shaped ring such as an aliphatic aromatic ring or a heteroaromatic ring) in a side chain (for example, , Polystyrene, poly (4-hydroxy) styrene, styrene polymers such as styrene-maleic anhydride copolymer, polyvinylpyridine, etc.), (meth) acrylic polymers such as polymethyl methacrylate, cellulose ester polymers (birefringence) Polyester polymers (excluding those with positive birefringence), acrylonitrile polymers, alkoxysilyl polymers, or multi-component (binary, ternary, etc.) copolymer polymers, etc. Is mentioned. These may be used individually by 1 type and may use 2 or more types together. Further, when it is a copolymer, it may be a block copolymer or a random copolymer.
Among these, a polymer having a specific cyclic structure, a (meth) acrylic polymer, and an alkoxysilyl polymer are more preferable, and polystyrene, polyhydroxystyrene, polyvinylpyridine, and a (meth) acrylic polymer are particularly preferable.

The addition of the polymer having the specific cyclic structure is preferable because the Rth expression of the cellulose acylate film after film formation can be increased.
As the polymer having the specific cyclic structure, a polymer having an aliphatic aromatic ring in a side chain described in JP-A-2010-46834 can be preferably used. Among these, polystyrene and poly (4-hydroxy) styrene are preferable, and a copolymer of polystyrene and poly (4-hydroxy) styrene is more preferable. The copolymerization ratio (molar ratio) of the copolymer of polystyrene and poly (4-hydroxy) styrene is preferably 10/90 to 100/0, and more preferably 20/80 to 90/10. .
On the other hand, as the polymer having the specific cyclic structure, a polymer having a heteroaromatic ring such as polyvinylpyridine in the side chain can also be preferably used.

  When the (meth) acrylic polymer is added, the cellulose acylate film after film formation is excellent in transparency and moisture permeability is extremely low, and exhibits excellent performance as a protective film for a polarizing plate. As the (meth) acrylic polymer, compounds described in JP2009-1696A and International Publication WO2008-126535 can be preferably used. The (meth) acrylic polymer may have an aliphatic aromatic ring or a heteroaromatic ring in the 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, and preferably 700 to 50,000. More preferably, it is particularly preferably 700 to 100,000.
When the molecular weight is 500 or more, the volatility is good, and when the molecular weight is 100,000 or less, the compatibility with the cellulose acylate resin is good, so the film-forming property of the cellulose acylate film is also good. preferable.

In the film of the present invention, the compound having negative intrinsic birefringence is preferably added in an amount of 0 to 20% by mass, more preferably 0 to 15% by mass, more preferably 0 to 15% by mass relative to the cellulose acylate. It is particularly preferable to add 10% by mass.
On the other hand, the film of the present invention is produced by the method for producing the cellulose acylate film described later, so that even if these relatively expensive compounds having negative intrinsic birefringence are not included, the reverse wavelength Dispersibility is large. Therefore, in the film of the present invention, it is preferable that the addition amount of the compound having negative intrinsic birefringence is small from the viewpoint of reducing the manufacturing cost.

(Fine particles)
The present invention preferably contains fine particles as a matting agent. Examples of fine particles include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate and calcium phosphate. Can do.
Fine particles containing silicon are preferable in terms of low haze, and silicon dioxide is particularly preferable.
The average primary particle size of the fine particles is preferably 5 to 50 nm, and more preferably 7 to 20 nm. These are preferably contained mainly as secondary aggregates having a particle size of 0.05 to 0.3 μm.
Silicon dioxide fine particles are commercially available, for example, under the trade names Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600, NAX50 (Nippon Aerosil Co., Ltd.). be able to.
Zirconium oxide fine particles are commercially available under the trade names of Aerosil R976 and R811 (manufactured by Nippon Aerosil Co., Ltd.) and can be used.
Examples of the polymer include silicone resin, fluororesin, and acrylic resin. Silicone resins are preferable, and those having a three-dimensional network structure are particularly preferable. For example, Tospearl 103, 105, 108, 120, 145, 3120, and 240 (manufactured by Toshiba Silicone Co., Ltd.) It is marketed by name and can be used.
Among these, Aerosil 200V and Aerosil R972V are particularly preferably used because they have a large effect of reducing the friction coefficient while keeping the haze of the cellulose derivative film low.

  The content of these fine particles with respect to the cellulose acylate in the cellulose film of the present invention is preferably 0.05 to 1% by mass, particularly preferably 0.1 to 0.5% by mass. In the case of a cellulose derivative film having a multilayer structure by the co-casting method, it is preferable to contain fine particles of this addition amount on the surface.

(Antioxidant, thermal degradation inhibitor)
In the present invention, conventionally known antioxidants and thermal deterioration inhibitors can be used. In particular, lactone, sulfur, phenol, double bond, hindered amine, and phosphorus compounds can be preferably used. As the antioxidant and the thermal degradation inhibitor, compounds described in International Publication WO2008-126535 can be preferably used.

(Coloring agent)
In the present invention, a colorant may be used. The colorant means a dye or a pigment. In the present invention, the colorant means an effect of making the color tone of a liquid crystal screen blue, adjusting the yellow index, and reducing haze. As the colorant, compounds described in International Publication WO2008-126535 can be preferably used.

(Peeling accelerator)
In the present invention, a peeling accelerator may be used. As the peeling accelerator, compounds described in [0030] to [0041] of JP-A No. 2011-183759 can be preferably used.

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

(Film thickness)
The film of the present invention has a thickness of 10 to 45 μm. By using such a thin cellulose acylate film, a thin polarizing plate and a thin liquid crystal display device can be obtained. The film thickness of the film of the present invention is preferably 25 to 40 μm. When the film of this invention is a laminated film, the range of the total film thickness of a film is the said preferable range. The film thickness in the present invention refers to the 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.

(Re, Rth)
In the film of the present invention, the retardation in the plane and in the film thickness direction at a wavelength of 550 nm satisfies the following formulas (1) and (2).
Formula (1) 40nm <= Re (550) <= 150nm
(In formula (1), Re (550) represents in-plane retardation at a wavelength of 550 nm.)
Formula (2) 80 nm ≦ Rth (550) ≦ 350 nm
(In Formula (2), Rth (550) represents retardation in the film thickness direction at a wavelength of 550 nm.)
It is preferable that retardation is developed in such a range from the viewpoint of improving the contrast and blackness change of the liquid crystal display device.
The Re (550) is preferably 40 ≦ Re (550) ≦ 70 nm, and more preferably 45 ≦ Re (550) ≦ 65 nm.
The Rth (550) preferably satisfies 100 ≦ Rth (550) ≦ 200 nm, and more preferably satisfies 100 ≦ Rth (550) ≦ 130 nm.

(Nz)
In the film of the present invention, Nz (Nz = Rth (550) / Re (550) +0.5) is preferably 1.1 to 4.5, more preferably 2.0 to 3.5. More preferably, it is 2.1 to 3.2.
When Nz is in such a range, light leakage is more effectively improved from an oblique direction.

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

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

(Internal haze)
The cellulose acylate film of the present invention has an internal haze of 0.10% or less.
The haze represents a haze value (%) measured according to JIS K7136.
The internal haze of the film of the present invention is obtained by dropping several drops of glycerin on both sides of the obtained cellulose acylate film and sandwiching it from both sides with two 1.3 mm thick glass plates (MICRO SLIDE GLASS product number S9213, manufactured by MATSUNAMI). The value (%) obtained by subtracting the haze measured in a state where several drops of glycerin were dropped between two sheets of glass from the haze value (%) measured in an open state.
The haze of the cellulose acylate film of the present invention was measured using a turbidimeter (NDH2000, Nippon Denshoku Industries Co., Ltd.) in a film that was allowed to stand for 24 hours in an environment of 23 ° C. and 55% relative humidity. It was measured.

The internal haze of the cellulose acylate film of the present invention is preferably 0.04% or less, and more preferably 0.02% or less.
A lower haze is generally preferred. Further, simply reducing the total haze is insufficient for improving the front contrast, and adjusting the inner haze to the above range is preferable from the viewpoint of improving the front contrast of the liquid crystal display device.

(Difference in moisture content (ΔM))
In the cellulose acylate film of the present invention, the difference between the equilibrium moisture content after immersion in pure water at 40 ° C. for 24 hours and the equilibrium moisture content before immersion is less than 1.0%, preferably 0.5% or less. . By reducing the difference in the equilibrium moisture content in this way, unevenness due to condensation does not occur even when adhering to water, and appropriate display performance can be obtained. The equilibrium moisture content is a value measured by the Karl Fischer method.
Such a film is obtained by producing the film of the present invention by methanol immersion.

(Dimensional change after humidity heat treatment)
It is preferable that the dimensional change rate after the film of this invention is processed for 24 hours at 60 degreeC and 90% of relative humidity satisfy | fills following formula (4) and (5).
Formula (4) ΔL (MD) / L (MD)> 0.10%
Expression (5) ΔL (TD) / L (TD)> 0.30%
(Where L (MD) and L (TD) represent the longitudinal and lateral dimensions, respectively, before treatment for 24 hours at 60 ° C. and 90% relative humidity, ΔL (MD) and ΔL (TD) Represents the amount of dimensional change in the vertical and horizontal directions after treatment for 24 hours at 60 ° C. and 90% relative humidity, respectively.
By setting it as such a range, the effect that the nonuniformity after processing the television which mounted the film in a humid heat environment is reduced is exhibited.

In Formula (4), it is more preferable that ΔL (MD) / L (MD)> 0.15%. In Formula (5), it is more preferable that ΔL (TD) / L (TD)> 0.35%.
Such a film is obtained by producing the film of the present invention by methanol immersion.

The cellulose acylate film of the present invention preferably satisfies ΔRe (550) <− 5 nm and ΔRth (550) <− 5 nm. Here, ΔRe (550) is (retardation in the in-plane direction at a wavelength of 550 nm of the cellulose acylate film after being treated for 24 hours at 60 ° C. and 90% relative humidity) − (24 at 60 ° C. and 90% relative humidity). In-plane direction retardation at a wavelength of 550 nm of the cellulose acylate film before the time treatment. ΔRth (550) is (retardation in the thickness direction at a wavelength of 550 nm of a cellulose acylate film after being treated at 60 ° C. and 90% relative humidity for 24 hours) − (treated at 60 ° C. and 90% relative humidity for 24 hours) It is retardation in the thickness direction at a wavelength of 550 nm of the previous cellulose acylate film.
By setting it as such a range, the effect that the nonuniformity after processing the television which mounted the film in a humid heat environment is reduced is exhibited.
More preferably, the film of the present invention satisfies ΔRe (550) <− 7 nm and ΔRth (550) <− 7 nm.
Such a film is obtained by producing the film of the present invention by methanol immersion.

[Method for producing cellulose acylate film]
The cellulose acylate film of the present invention can be produced according to a known method.
Furthermore, in the present invention, a step of forming a polymer solution having a cellulose acylate having a total substitution degree of 2.0 to 2.95, a solvent, and an additive containing an aromatic into a film, and after stretching the film The manufacturing method of the cellulose acylate film characterized by including the process of extending | stretching by controlling so that a film thickness may be set to 10-45 micrometers, and also including the process of water-treating this stretched film is disclosed. These details will be described below.

As a method for producing a cellulose acylate film, a film containing cellulose acylate can be formed using a solution casting film forming method or a melt film forming method. From the viewpoint of improving the surface shape of the film, the method for producing a cellulose acylate film preferably includes a step of forming a film containing cellulose acylate by solution casting.
Hereinafter, although the manufacturing method of a cellulose acylate film is demonstrated to the case where the solution casting film forming method is used for an example, the manufacturing method of a cellulose acylate film is not limited to the solution casting film forming method. In addition, about the case where the said melt film forming method is used as a manufacturing method of the said cellulose acylate film, a well-known method can be used.

<Polymer solution>
In the solution casting film forming method, a web is formed using the cellulose acylate or a polymer solution (cellulose acylate solution) containing various additives as required. In the present invention, it is usually preferable that an additive is blended and an additive containing an aromatic is blended. Hereinafter, a polymer solution (hereinafter sometimes referred to as a cellulose acylate solution or a dope as appropriate) that can be used in the solution casting film forming method will be described.

(solvent)
The cellulose acylate used in the present invention is dissolved in a solvent to form a dope, which is cast on a 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.
Furthermore, it does not react with a reactive metal compound or a catalyst, and does not dissolve the casting base material. Two or more solvents may be mixed and used.
Alternatively, cellulose acylate and a reactive metal compound capable of hydrolysis polycondensation may be dissolved in different solvents and then mixed.
Here, an organic solvent having good solubility in the cellulose acylate is referred to as a good solvent, and exhibits a main effect on dissolution, and an organic solvent used in a large amount among them is a main (organic) solvent or a main ( Organic) solvent.

  Examples of the good solvent include ketones such as acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, ethers such as tetrahydrofuran (THF), 1,4-dioxane, 1,3-dioxolane, 1,2-dimethoxyethane, and formic acid. Esters such as methyl, ethyl formate, methyl acetate, ethyl acetate, amyl acetate, γ-butyrolactone, methyl cellosolve, dimethylimidazolinone, dimethylformamide, dimethylacetamide, acetonitrile, dimethyl sulfoxide, sulfolane, nitroethane, methylene chloride And 1,3-dioxolane, THF, methyl ethyl ketone, acetone, methyl acetate and methylene chloride are preferable.

The dope preferably contains 1 to 40% by mass of an alcohol having 1 to 4 carbon atoms in addition to the organic solvent.
After casting the dope on the metal support, the solvent starts to evaporate and the ratio of alcohol increases so that the web (the name of the dope film after casting the cellulose acylate dope on the support is called It is used as a gelling solvent that makes it easy to peel off from the metal support, and when these ratios are small, it promotes dissolution of cellulose acylate of non-chlorine organic solvent There is also a role to suppress gelation, precipitation, and viscosity increase of the reactive metal compound.

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.
Of these, ethanol is preferred because it has excellent dope stability, has a relatively low boiling point, good drying properties, and no toxicity. These organic solvents alone are not soluble in cellulose acylate and are referred to as poor solvents.

In the present invention, the cellulose acylate constituting the cellulose acylate film contains hydrogen bonding functional groups such as hydroxyl groups, esters, and ketones, and therefore 5 to 30% by mass, more preferably 7 to 25% by mass in the total solvent. More preferably, it contains 10 to 20% by mass of alcohol from the viewpoint of reducing the peeling load from the casting support.
By adjusting the alcohol content, it is possible to easily adjust the expression of Re and Rth of the cellulose acylate film produced by the method for producing a cellulose acylate film. Specifically, by increasing the alcohol content or setting the drying temperature (heat treatment temperature) before stretching in the method for producing the cellulose acylate film described later, the reach range of Re and Rth can be further increased. It becomes possible to enlarge.
Further, in the present invention, it is effective to contain a small amount of water to increase the solution viscosity and the film strength in the wet film state at the time of drying, or to increase the dope strength at the time of casting the drum method. It may be contained in an amount of 0.1 to 5% by mass, more preferably 0.1 to 3% by mass, and particularly 0.2 to 2% by mass.

  Examples of combinations of organic solvents preferably used as the solvent for the polymer solution in the present invention are described in JP-A-2009-262551.

  In addition, if necessary, a non-halogen organic solvent can be used as a main solvent, and detailed description can be found in the Japan Institute of Invention Publication (Publication No. 2001-1745, published on March 15, 2001, Invention Association). There is a description.

The cellulose acylate concentration in the polymer solution in the present invention is preferably 5 to 40% by mass, more preferably 10 to 30% by mass, and most preferably 15 to 30% by mass.
The cellulose acylate concentration can be adjusted to a predetermined concentration at the stage of dissolving the cellulose acylate in a solvent. Further, after preparing a low concentration (for example, 4 to 14% by mass) solution in advance, the solution may be concentrated by evaporating the solvent. Furthermore, after preparing a high concentration solution in advance, it may be diluted. Moreover, the density | concentration of a cellulose acylate can also be reduced by adding an additive.

  The timing of adding the additive can be appropriately determined according to the type of the additive.

  The most preferable solvent that satisfies such conditions and dissolves cellulose acylate, which is a preferred polymer compound, at a high concentration is a mixed solvent having a ratio of methylene chloride: ethyl alcohol of 95: 5 to 80:20. Alternatively, a mixed solvent of methyl acetate: ethyl alcohol 60:40 to 95: 5 is also preferably used.

<Details of each process>
(1) Dissolution step A step of dissolving the cellulose acylate and additives in an organic solvent mainly containing a good solvent for cellulose acylate while stirring to form a dope, or an additive in a cellulose acylate solution This is a step of mixing a solution to form a dope.
For dissolving cellulose acylate, a method carried out at normal pressure, a method carried out below the boiling point of the main solvent, a method carried out under pressure above the boiling point of the main solvent, JP-A-9-95544, JP-A-9-95557 Alternatively, various dissolution methods such as a cooling dissolution method as described in JP-A-9-95538 and a high-pressure method as described in JP-A-11-21379 can be used. The method of pressurizing at a boiling point or higher is preferred.
The concentration of cellulose acylate in the dope is preferably 10 to 35% by mass. An additive is added to the dope during or after dissolution to dissolve and disperse, then filtered through a filter medium, defoamed, and sent to the next step with a liquid feed pump.

(2) Casting process An endless metal belt that feeds the dope to a pressure die through a liquid feed pump (for example, a pressurized metering gear pump) and transfers it infinitely, such as a stainless steel belt, or a metal such as a rotating metal drum This is a step of casting the dope from the pressure die slit to the casting position on the support.
A pressure die that can adjust the slit shape of the die base and facilitates uniform film thickness is preferred. The pressure die includes a coat hanger die and a T die, and any of them is preferably used. The surface of the metal support is a mirror surface. In order to increase the film forming speed, two or more pressure dies may be provided on the metal support, and the dope amount may be divided and stacked. Or it is also preferable to obtain the film of a laminated structure by the co-casting method which casts several dope simultaneously.

(3) Solvent evaporation process The web (the state before the cellulose acylate film is completed, which still contains a lot of solvent) is heated on the metal support, and the web peels from the metal support. This is the process of evaporating the solvent until it becomes possible.
To evaporate the solvent, there are a method of blowing air from the web side and / or a method of transferring heat from the back side of the metal support by a liquid, a method of transferring heat from the front and back by radiant heat, etc. However, drying efficiency is preferable. A method of combining them is also preferable. In the case of backside liquid heat transfer, it is preferable to heat at or below the boiling point of the main solvent of the organic solvent used in the dope or the organic solvent having the lowest boiling point.

(4) Peeling process It is the process of peeling the web which the solvent evaporated on the metal support body in a peeling position. The peeled web is sent to the next process. In addition, if the residual solvent amount (the following formula) of the web at the time of peeling is too large, peeling is difficult, or conversely, if the film is peeled off after being sufficiently dried on the metal support, a part of the web is in the middle. It may come off.
Here, there is a gel casting method (gel casting) as a method for increasing the film forming speed (the film forming speed can be increased by peeling while the residual solvent amount is as large as possible). For example, there are a method in which a poor solvent for cellulose acylate is added to the dope and the dope is cast and then gelled, a method in which the temperature of the metal support is lowered and gelled. By gelling on the metal support and increasing the strength of the film at the time of peeling, the speed of film formation can be increased by speeding up the peeling.
The amount of residual solvent during peeling of the web on the metal support is preferably within a range of 5 to 150% by mass depending on the strength of drying conditions, the length of the metal support, etc., but the amount of residual solvent is larger. In the case of peeling at the time, the amount of residual solvent at the time of peeling is determined in consideration of economic speed and quality. In the present invention, the temperature at the peeling position on the metal support is preferably -50 to 40 ° C, more preferably 10 to 40 ° C, and most preferably 15 to 30 ° C.

The residual solvent amount of the web at the peeling position is preferably 10 to 150% by mass, and more preferably 10 to 120% by mass.
The amount of residual solvent can be represented by the following formula.
Residual solvent amount (% by mass) = [(MN) / N] × 100
Here, M is the mass of the web at an arbitrary point in time, and N is the mass when the mass M is dried at 110 ° C. for 3 hours.

(5) Drying or heat treatment step, stretching step The method for producing a cellulose acylate film of the present invention is characterized by performing a stretching step on the peeled film. Furthermore, it is preferable to perform the said extending | stretching process at the temperature of Tg-20 degreeC-TgdegreeC from a viewpoint of improving the optical expression with respect to the film thickness of the cellulose acylate film obtained. Tg represents the glass transition temperature (unit: ° C.) of the cellulose acylate film of the present invention, and tan δ has a peak when the dynamic viscoelasticity tan δ of the cellulose acylate film when the residual volatile content is 0% is measured. It means the temperature shown.
After the peeling step, the web is transferred using a drying device that alternately conveys the web through a plurality of rolls arranged in the drying device, and / or a tenter device that conveys the web while clipping both ends with the clip. It is preferable to dry.

In the method for producing a cellulose acylate film, the web may or may not be heat-treated before stretching.
The drying or heat treatment temperature is preferably 30 minutes or less, more preferably 20 minutes or less, and particularly preferably about 10 minutes.

  As a means for drying and heat treatment, hot air is generally blown on both sides of the web, but there is also a means for heating by applying a microwave instead of the wind. The temperature, air volume, and time vary depending on the solvent used, and the conditions may be appropriately selected according to the type and combination of the solvents used.

  In the method for producing the cellulose acylate film, the cellulose acylate film may be stretched in any direction of the film transport direction (hereinafter also referred to as the longitudinal direction) and the direction orthogonal to the film transport direction (hereinafter also referred to as the lateral direction). Stretching in the transverse direction is preferable from the viewpoint of expressing desired retardation. Stretching may be performed in one stage or in multiple stages.

The draw ratio in stretching in the film transport direction is preferably 0 to 20%, more preferably 0 to 15%, and particularly preferably 0 to 10%. The stretch ratio (elongation) of the cellulose acylate web during the stretching can be achieved by the difference in peripheral speed between the metal support speed and the stripping speed (stripping roll draw). For example, when an apparatus having two nip rolls is used, the cellulose acylate film is preferably stretched in the transport direction (longitudinal direction) by increasing the rotational speed of the nip roll on the outlet side rather than the rotational speed of the nip roll on the inlet side. can do. By performing such stretching, the expression of retardation can be adjusted.
Here, the “stretch ratio (%)” means that obtained by the following formula.
Stretch ratio (%) = 100 × {(Length after stretching) − (Length before stretching)} / Length before stretching

The stretching ratio in stretching in the direction perpendicular to the film conveying direction is preferably more than 20%, more preferably more than 20% to 60% or less, particularly preferably 25 to 55%, 25 More preferably, it is ˜50%.
In the present invention, it is preferable to stretch using a tenter device as a method of stretching in a direction perpendicular to the film conveying direction.

  In the method for producing a cellulose acylate film, the stretching temperature is preferably Tg-20 ° C to Tg. Tg is the glass transition temperature of cellulose acylate.

  In a more preferred embodiment of the method for producing a cellulose acylate film, cellulose acetate having a low acetyl substitution degree (particularly cellulose acetate having an acetyl substitution degree of 2.0 to 2.5) is used, and in the range of the stretching temperature. By extending | stretching, the haze resulting from the said extending | stretching can also be suppressed. Without being 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 composed of the aliphatic dicarboxylic acid residue and the aliphatic diol residue. Since the difference in refractive index from the polycondensed ester is high, scattering in the film is unlikely to occur. Moreover, haze can be further suppressed by selecting what has high compatibility with the cellulose acetate of a low acetyl substitution degree as said polycondensation ester. As a result, the internal haze of the film obtained by the method for producing the cellulose acylate film can be easily controlled within the preferable range.

 In the manufacturing method of the film of this invention, since it suppresses generation | occurrence | production of craze and does not express internal haze, it is preferable to extend | stretch at Tg-10 degreeC-Tg + 40 degreeC. Tg-5 ° C to Tg + 30 ° C is more preferable, and Tg to Tg + 20 ° C is particularly preferable. An internal haze raise can be suppressed by making extending | stretching temperature into the said temperature range.

  In addition, you may dry before the wet heat treatment process mentioned later after an extending process. When drying after the stretching step and before the wet heat treatment step described later, the drying temperature, the amount of drying air and the drying time differ depending on the solvent used, and the drying conditions may be appropriately selected according to the type and combination of the solvents used. In the present invention, the drying temperature after the stretching step and before the wet heat treatment step, which will be described later, is lower than the stretching temperature in the stretching step, so that the front contrast when the film of the present invention is incorporated in a liquid crystal display device is increased. To preferred.

(6) Methanol solution treatment process In this invention, a methanol solution process is carried out in the state which made the residual solvent of the cellulose acylate film 5 mass% or less. As a method of setting the residual solvent of the cellulose acylate film to 5% by mass or less, a method of drying after stretching is preferable.
As the methanol solution treatment, it is preferable to immerse in a methanol solution after stretching. The temperature of the methanol solution is preferably 0 to 150 ° C, more preferably 15 to 60 ° C. If the temperature of the methanol solution is high, the effects of the present invention tend to be obtained in a short time. However, since the operation becomes complicated if the boiling point of the solvent is exceeded, it is preferable to adjust the temperature below the boiling point.
The immersion time in the methanol solution is 1 second to 60 minutes. By setting it to 1 second or more, the effect of this invention is exhibited more effectively and it is preferable from a viewpoint of a productivity improvement to set it as 60 minutes or less. Further, by increasing the temperature of the methanol solution to be immersed, the effect of the present invention tends to be obtained even if the immersion time is short. However, if the temperature is too high, wrinkles tend to be more easily caused during transportation.

The methanol solution used for these immersion and methanol solution vapor aeration may be a mixed solvent containing 20% by mass or more of methanol, more preferably 30% by mass or more, and further preferably 40% by mass or more.
Examples of the solvent mixed with the methanol solution include water and dichloromethane. Of these, dichloromethane is more preferable.

(7) Drying step The cellulose acylate film treated with the methanol solution may be cooled as it is to about room temperature, or subsequently conveyed to the drying zone in order to adjust the amount of contact gas molecules remaining in the film. Also good. When transporting to the drying zone, the cellulose acylate film transported by a group of rolls or the cellulose acylate film transported while being clipped at both ends by a tenter, a method of drying at normal temperature, hot air or warm air, gas There are a method of applying a low-concentration wind, a method of irradiating heat rays, a method of contacting a heated roll, and the like, but a method of drying at normal temperature is preferable.

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

  The length of the film obtained as described above is preferably wound at 100 to 10000 m per roll, more preferably 500 to 7000 m, and further preferably 1000 to 6000 m. The width of the film is preferably 0.5 to 5.0 m, more preferably 1.0 to 3.0 m, and still more preferably 1.0 to 2.5 m. When winding, it is preferable to give knurling to at least one end, the knurling width is preferably 3 mm to 50 mm, more preferably 5 mm to 30 mm, and the height is preferably 0.5 to 500 μm, more preferably 1 to 200 μm. is there. This may be a single push or a double push.

  The film of the present invention is particularly suitable for use in a large screen liquid crystal display device. When used as an optical compensation film for a large-screen liquid crystal display device, for example, the film width is preferably set to 1470 mm or more. In addition, the optical compensation film of the present invention is produced not only in the form of a film piece cut into a size that can be incorporated into a liquid crystal display device as it is, but also in a long shape by continuous production, and in a roll shape. The film of the aspect wound up by this is also included. The optical compensation film of the latter mode is stored and transported in that state, and is cut into a desired size and used when actually incorporated into a liquid crystal display device or bonded to a polarizer or the like. Similarly, it is cut into a desired size when it is actually incorporated into a liquid crystal display device after being bonded to a polarizer or the like made of a polyvinyl alcohol film or the like that has been made into a long shape. Used. As one mode of the optical compensation film wound up in a roll shape, a mode in which the roll length is rolled up to 2500 m or more can be mentioned.

  The web thus obtained is 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 the range of the preferable film thickness of the said cellulose acylate film from a viewpoint of manufacturing cost or optical characteristic expression.

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

<Optical film>
The present invention also relates to an optical film having the cellulose acylate film of the present invention and a retardation layer in which the alignment state of the liquid crystal material is fixed.
The retardation layer contains a liquid crystal compound that is homeotropically aligned, and the optical properties of the retardation layer satisfy the following formulas (1), (2), and (3).
80 ≦ Re ≦ 150 Formula (1)
−100 ≦ Rth ≦ 10 Formula (2)
0.05 ≦ | Rth / Re | ≦ 1.0 Formula (3)

In the formula (1), 85 ≦ Re ≦ 140 is preferable, and 90 ≦ Re ≦ 130 is more preferable.
In Formula (2), −95 ≦ Rth ≦ 5 is preferable, and −90 ≦ Rth ≦ 0 is more preferable.
In the formula (3), 0.1 ≦ | Rth / Re | ≦ 0.95 is preferable, and 0.15 ≦ | Rth / Re | ≦ 0.90 is more preferable.

The retardation layer contains a liquid crystal compound that is homeotropically aligned, and an example is a layer formed by fixing the homeotropic alignment of a composition containing a rod-like liquid crystal as a main component.
Usable rod-like liquid crystals are described in, for example, [0045] to [0066] of JP-A-2009-217256, and can be referred to. The usable additive, the usable alignment film, and the method for forming the homeotropic liquid crystal layer are described in, for example, [0076] to [0079] of JP-A-2009-237421. Can do.

An intermediate layer may be provided between the cellulose acylate film of the present invention and the retardation layer. The intermediate layer is preferably isotropic so as not to optically affect other structures, and the material is compatible when considering the adhesion between the cellulose acylate film of the present invention and the retardation layer. Higher properties are preferred.
The intermediate layer preferably contains a polyvinyl alcohol resin and an acrylic resin having a polar group.

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

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

<Liquid crystal display device>
The liquid crystal display device of the present invention can be used for liquid crystal display devices in various display modes. Each liquid crystal mode in which these films are used will be described below. Among these modes, the polarizing plate of the present invention is particularly preferably used for TN, STN, VA, and IPS mode liquid crystal display devices. These liquid crystal display devices may be any of a transmissive type, a reflective type, and a transflective type.

(TN mode liquid crystal display)
It is most frequently used as a color TFT liquid crystal display device and is described in many documents. The alignment state in the liquid crystal cell in the TN mode black display is an alignment state in which the rod-like liquid crystalline molecules rise at the center of the cell and the rod-like liquid crystalline molecules lie in the vicinity of the cell substrate. TN mode liquid crystal cells and TN type liquid crystal display devices have been well known for a long time. As for the optical compensation sheet used in the TN type liquid crystal display device, each of JP-A-3-9325, JP-A-6-148429, JP-A-8-50206, and JP-A-9-26572, and Mori. There are descriptions in other papers (Jpn. J. Appl. Phys. Vol. 36 (1997) p. 143 and Jpn. J. Appl. Phys. Vol. 36 (1997) p. 1068).

(VA mode liquid crystal display device)
The feature is that the rod-like liquid crystalline molecules are oriented substantially vertically when no voltage is applied. In the VA mode liquid crystal cell, (1) the rod-like liquid crystalline molecules are oriented substantially vertically when no voltage is applied. In addition to a narrowly defined VA mode liquid crystal cell (described in JP-A-2-176625) that is aligned substantially horizontally when a voltage is applied, (2) the VA mode is multi-domained to expand the viewing angle ( Liquid crystal cell (in MVA mode) (SID97, Digest of tech. Papers 28 (1997) 845), (3) Rod-like liquid crystal molecules are substantially vertically aligned when no voltage is applied, and twisted A liquid crystal cell in a domain alignment mode (n-ASM mode) (described in the proceedings 58-59 (1998) of the Japanese Liquid Crystal Society) and (4) a SURVAVAL mode liquid crystal cell (LCD interface) Announced at National 98). The VA-type liquid crystal display device may be an alignment-divided system as described in, for example, JP-A-10-123576.

(IPS mode liquid crystal display)
The feature is that the rod-like liquid crystalline molecules are aligned substantially horizontally in the plane when no voltage is applied, and this is characterized by switching by changing the orientation direction of the liquid crystal with or without voltage application. Specifically, JP 2004-365951 A, JP 2004-12731 A, JP 2004-215620 A, JP 2002-221726 A, JP 2002-55341 A, JP 2003-195333 A. Those described in the publication can be used.
In these modes, the liquid crystal material is aligned substantially in parallel during black display, and black is displayed by aligning liquid crystal molecules in parallel with the substrate surface in the absence of applied voltage. In these embodiments, the polarizing plate using the transparent cellulose acylate film of the present invention contributes to widening the viewing angle and improving the contrast.

  The present invention will be described more specifically with reference to the following examples. The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention is not limited to the specific examples shown below.

  In the present invention, film properties were measured by the following measuring method.

(Measurement method of orientation)
<Orientation degree P_p of cellulose acylate>
The degree of orientation P_p calculated by X-ray diffraction measurement was used as a parameter indicating the orientation of cellulose acylate. For X-ray diffraction measurement, RAPID R-AXIS manufactured by Rigaku Denki Kogyo Co., Ltd. was used, CuKα rays were used as the X-ray source, and X-rays were generated at 40 kV-36 mA. The collimator was 0.8 mmφ, and the cellulose acylate film as a sample was fixed using a transmission sample stage. The measurement was performed under the conditions of 22 ° C. and 60% RH. The degree of orientation P of cellulose acylate is defined by the following formula (A) from the detected X-ray pattern. The upper limit value of the degree of orientation P is 1.0.

P = <3cos2β-1> / 2 Expression (A)
However, <cos2β> = ∫ (0, π) cos2βI (β) sinβdβ / ∫ (0, π) I (β) sinβdβ.
In the above formula, β is an angle formed between the incident surface of the incident X-ray and one direction in the cellulose acylate film surface, and I is 2θ = 8 ° in the X-ray diffraction chart measured at the angle β. The diffraction intensity at.

<Orientation degree of additive>
The degree of orientation P2 calculated by Raman spectroscopy was used as the parameter P # a indicating the orientation of the additive. The Raman spectroscopic measurement was performed using a nanofinder 30 manufactured by Tokyo Instruments Inc. under the conditions of an incident laser wavelength of 785 nm and an objective lens of 20 times. The degree of orientation was calculated using 980 cm ⁻¹ .
The angle between the MD direction of the sample and the polarization direction of the laser is defined as the sample azimuth angle β, the sample is rotated from 0 ° to 180 °, and Raman scattering is measured. At that time, the direction of the analyzer is set parallel (I _|| (β)) and perpendicular (I⊥ (β)) to the polarization plane of the incident laser, and the polarization Raman spectrum is measured for each.
The ratio of I _|| (β) and II (β) is obtained with respect to the sample azimuth angle β, and <P ₂ > is obtained by least square fitting with a theoretical formula.

The vibrating Raman line is characterized by a Raman tensor. A Raman line having a Raman tensor that can approximate a uniaxial symmetry such as stretching vibrations of a cyano group, a phenyl group, or a carbonyl group can be used as a probe for orientation analysis (Formula a).

ここで、dはサンプルの厚さ、l、l'はそれぞれ入射光と散乱光の波長である。a、bはラマンテンソルの値で決まる値であり、それぞれラマンテンソルの等方値と異方値である。
a = (2a⊥ + a_||)/3, b = a_|| - a⊥ The Raman line used for orientation analysis is fitted with the Voigt function, and at each rotation angle, the parallel intensity I _|| having the polarization component parallel to the polarization plane of the incident light and the vertical intensity I⊥ having the polarization component perpendicular to each other are obtained. Calculate the intensity.
<P ₂ > and <P ₄ > can be obtained by least square fitting with the following theoretical formula for the rotation angle dependence of the ratio of I _|| and I⊥.

Here, d is the thickness of the sample, and l and l ′ are the wavelengths of incident light and scattered light, respectively. a and b are values determined by the value of the Raman tensor, and are the isotropic value and the anisotropic value of the Raman tensor, respectively.
a = (2a⊥ + a _|| ) / 3, b = a _|| -a⊥

<P ₄ > is the fourth order orientation parameter,
<P ₄ > = <(35 cos ⁴ q-30 cos ² q + 3) / 8>
It is. a / b is obtained from the relational expression R _iso = 3 b ² / (45 a ² + 4 b ² ) from the measured depolarization degree R _iso when the control agent molecules are isotropically distributed. It is done.

<Orientation ratio>
P_a / P_p was calculated from the degree of orientation P_p of cellulose acylate and the degree of orientation P_a of the additive containing aromatics calculated as described above.

(optical properties)
Re and Rth were measured at a wavelength of 590 nm by KOBRA 21ADH (manufactured by Oji Scientific Instruments) by the above method.

(Internal haze)
Several drops of glycerin were dropped on both sides of the obtained cellulose acylate film sample 40 mm × 80 mm, and sandwiched from both sides by two 1.3 mm thick glass plates (MICRO SLIDE GLASS product number S9213, manufactured by MATSUNAMI) at 25 ° C. From the haze value measured according to JIS K-6714 with a haze meter (HGM-2DP, Suga test machine) at a relative humidity of 60%, the haze measured with a few drops of glycerin dropped between two glasses was subtracted. The value (%) was defined as internal haze.

(Preparation of cellulose acylate film 101)
(1) Dope preparation The following composition is put into a mixing tank, stirred to dissolve each component, further heated to 90 ° C. for about 10 minutes, and then filtered with a filter paper having an average pore size of 34 μm and a sintered metal filter having an average pore size of 10 μm. Filtered.
――――――――――――――――――――――――――――――――――
Cellulose acylate solution ――――――――――――――――――――――――――――――――――
Cellulose acylate described in the following table Total 100.0 parts by mass Polycondensed ester (E1) described below (Amounts shown in the following table Unit: parts by mass)
Dichloromethane 403.0 parts by mass Methanol 60.2 parts by mass ―――――――――――――――――――――――――――――――――

Ｅ１は、ＡＡ（アジピン酸）とＥＧ（エチレングリコール）を反応させ、末端をＯＡｃ（Ａｃはアセチル基）で封止した化合物である。
Ｅ２は、ＴＰＡ（テレフタル酸）、ＳＡ（コハク酸）、ＥＧ（エチレングリコール）、ＰＧ（１，２−プロピレングリコール）を反応させ、末端をＡｃで封止した化合物である。 Polycondensation ester 1 and polycondensation ester 2:

E1 is a compound in which AA (adipic acid) and EG (ethylene glycol) are reacted and the ends are sealed with OAc (Ac is an acetyl group).
E2 is a compound in which TPA (terephthalic acid), SA (succinic acid), EG (ethylene glycol), and PG (1,2-propylene glycol) are reacted and the ends are sealed with Ac.

<1-2> Matting Agent Dispersion Next, the following composition containing the cellulose acylate solution prepared by the above method was charged into a disperser to prepare a matting agent dispersion.
――――――――――――――――――――――――――――――――――――
Matting agent dispersion ――――――――――――――――――――――――――――――――――――
-Matting agent (Aerosil R972) 0.2 parts by mass-Dichloromethane 72.4 parts by mass-Methanol 10.8 parts by mass-Cellulose acylate solution 10.3 parts by mass--------- ――――――――――――――――――――――
The cellulose acylate solution was mixed in an amount of 100 parts by mass, and the matting agent dispersion was mixed in an amount of 0.02 parts by mass of inorganic fine particles with respect to the cellulose acylate resin to prepare a dope for film formation.

(2) Casting The above-mentioned dope was cast using a band casting machine. The band was made of SUS.

(3) Drying The web (film) obtained by casting was peeled from the band, and then dried for 20 minutes in the tenter device using a tenter device that clips and conveys both ends of the web with clips. In addition, the drying temperature here means the film surface temperature of a film.

(4) Stretching The obtained web (film) is peeled off from the band, sandwiched between clips, and transported using a tenter under the stretching conditions shown in the following table when the amount of residual solvent relative to the total film mass is 30%. It extended | stretched in the direction (lateral direction) orthogonal to a direction. However, no stretching was carried out for examples not described in the column of stretching conditions in the table. At this time, the cast film thickness was adjusted so that the film thickness after stretching became the film thickness (unit: μm) described in the table.

(5) Methanol solution immersion The methanol solution of the composition of the following table was adjusted for the stretched film, and the film was immersed at the temperature and time described in the following table while transporting the film. The film immersed in the methanol solution was taken out and dried at room temperature for 10 minutes.

 Thereafter, after drying at room temperature, a roll having a roll width of 1280 mm and a roll length of 2600 mm was produced at least 24 rolls under the above conditions for the purpose of winding the film and judging its production suitability. A sample (width 1280 mm) having a length of 1 m was cut out at intervals of 100 m for one of 24 rolls produced continuously.

Other cellulose acylate films were prepared in the same manner as above except that the substitution degree of cellulose acylate, polycondensed ester, sugar ester, and nitrogen-containing aromatic ring compound, and production conditions were changed as shown in the following table. Produced.
The following evaluation was performed about the obtained cellulose acylate film.

(Evaluation of tearing)
Tear strength: A sample of 64 mm x 51 mm is conditioned for 3 hours or more at 25 ° C and 65% RH. Under that condition, a razor is cut and the resistance force (g) when tearing up and down is a light load tear tester. (Toyo Seiki) was used for measurement.
A: Tear strength 6 g or more B: Tear strength 4 g or more C: Tear strength less than 2 g

(ΔRe, ΔRth)
ΔRe (550) is (retardation in the in-plane direction at a wavelength of 550 nm of the cellulose acylate film after being treated at 60 ° C. and 90% relative humidity for 24 hours) − (treated at 60 ° C. and 90% relative humidity for 24 hours) It was calculated as retardation in the in-plane direction at a wavelength of 550 nm of the previous cellulose acylate film.
ΔRth (550) is (retardation in the thickness direction at a wavelength of 550 nm of a cellulose acylate film after being treated at 60 ° C. and 90% relative humidity for 24 hours) − (treated at 60 ° C. and 90% relative humidity for 24 hours) It calculated as the retardation of the thickness direction in wavelength 550nm of the previous cellulose acylate film.

(Measurement of equilibrium moisture content)
The equilibrium moisture content was measured by the Karl Fischer method as follows.
(1) A sample (two 0.9 m × 4.5 cm) was weighed. When the sample was wet, the surface moisture was quickly wiped. Immediately after sampling, the sample was placed in a glass bottle with a polish plug and carried to a moisture meter, and measurement was made within 3 minutes after sampling.
(2) It measured using the following moisture meter.
-Vaporizer: The VA-05 type made by Mitsubishi Chemical was used, and the moisture in the sample was volatilized at 150 ° C and introduced into the moisture meter.
Moisture meter: Measured using a Karl Fischer moisture meter (CA-03 model manufactured by Mitsubishi Chemical).
(3) The moisture content (μg) indicated by the moisture meter was W, the weighed sample amount was F (mg), and the equilibrium moisture content was calculated from the following equation.
Equilibrium moisture content (%) = 100 × (W / 1000F) = 0.1 × (W / F)

(Equilibrium water content before and after water immersion (ΔM))
The obtained film was cut into 10 cm × 10 cm and immersed in pure water at 40 ° C. for 24 hours. Thereafter, the water on the surface was wiped off, dried with warm air at 100 ° C. for 5 minutes, conditioned at 25 ° C. and 80% relative humidity for 24 hours, and the film equilibrium moisture content was measured by the Karl Fischer method. Moreover, the equilibrium moisture content after water immersion and the equilibrium moisture content before water immersion were compared and the change in equilibrium moisture content was calculated.

糖エステルＡ１：

特開２０１２−３１３１３号公報の記載に従って合成した。
含窒素芳香族系化合物Ｎ１：

含窒素芳香族系化合物Ｎ２：

液晶性化合物Ｌ１：

Sugar ester A1:

Synthesized according to the description in JP 2012-31313 A.
Nitrogen-containing aromatic compound N1:

Nitrogen-containing aromatic compound N2:

Liquid crystalline compound L1:

(Preparation of polarizing plate sample)
Each polarizing plate was produced using the cellulose acylate film as follows.

  The surface of the film of each Example and Comparative Example prepared above was subjected to alkali saponification treatment. It was immersed in a 1.5 N aqueous sodium hydroxide solution at 55 ° C. for 2 minutes, washed in a water bath at room temperature, and neutralized with 0.1 N sulfuric acid at 30 ° C. Again, it was washed in a water bath at room temperature and further dried with hot air at 100 ° C. Subsequently, a roll-shaped polyvinyl alcohol film having a thickness of 80 μm was continuously stretched 5 times in an aqueous iodine solution and dried to obtain a polarizer having a thickness of 20 μm. Using the 3% aqueous solution of polyvinyl alcohol (Kuraray PVA-117H) as an adhesive, the alkali saponified films of Examples and Comparative Examples and the same alkali saponified Fujitac TD60UL (manufactured by FUJIFILM Corporation) were prepared. Then, the saponified surfaces are bonded to each other with the polarizer interposed therebetween, and the polarizing plates are obtained by bonding the films of the respective examples and comparative examples, the polarizer, and TD60UL in this order. It was. At this time, the films were pasted so that the MD direction of each film and the slow axis of TD60UL were parallel to the absorption axis of the polarizer.

(Production of VA mode liquid crystal display device)
The front and back polarizing plates and retardation plates of a VA mode liquid crystal TV (LC-46LX1, manufactured by SHARP) were peeled off and used as a liquid crystal cell. As in the configuration of FIG. 1 (upper side is the front side), an outer protective film (not shown), a polarizer 11, each example and comparative example film 14 (rear side cellulose acylate film) described in the following table, A liquid crystal cell 13 (the above VA liquid crystal cell), a film 15 (a cellulose acylate film on the front side), a polarizer 12 and an outer protective film (not shown) of the examples and comparative examples described in the following table were adhered in this order The liquid crystal display device of each Example and the comparative example was produced by bonding using the agent. At this time, they were bonded so that the absorption axes of the upper and lower polarizing plates were orthogonal to each other.

(Evaluation of liquid crystal display devices)
Various display characteristics of each produced liquid crystal display device were evaluated as follows.

<Front contrast>
Using a measuring instrument (BM5A, manufactured by TOPCON), the luminance values of black display and white display in the front direction of the panel were measured in a dark room, and the front contrast (white luminance / black luminance) was calculated.
The observed contrast was evaluated according to the following criteria.
A: 5000 or more B: 4500 or more and less than 5000 C: 4000 or more and less than 4500 D: less than 4000

<Viewing angle light leakage>
The manufactured liquid crystal display device was subjected to sensory evaluation of light leakage and color shift in an oblique direction during black display in a dark room, and evaluated according to the following criteria.
A: Almost no light leakage is observed in all polar and azimuthal directions.
B: Light leakage is slightly observed in a region where the polar angle is larger than 60 degrees.
C: Some light leakage is observed even in a region where the polar angle is less than 60 degrees.

(Preparation of optical films 1 and 2)
<Formation of intermediate layer (acrylic layer)>
The intermediate layer forming composition was prepared by mixing the compounds and solvents described in the following table.
100 parts by mass of two acrylic compounds (ACR1: ACR2 = 33: 67), 4 parts by mass of a photopolymerization initiator (Irgacure 127, manufactured by Ciba Specialty Chemicals) and methyl acetate / methyl isobutyl ketone (solvent) The composition for acrylic layer formation was prepared so that it might become 20 mass% in the liquid mixture of MIBK) = 70/30 (mass (%)).
The composition for forming an intermediate layer is applied on the cellulose acylate film 121 and the cellulose acylate film 122 with the composition for forming an acrylic layer using a wire bar coater # 1.6, dried at 60 ° C. for 0.5 minutes, and then 120 W The intermediate layer was crosslinked by UV irradiation at 30 ° C. for 30 seconds using a / cm high-pressure mercury lamp. The film thickness of the obtained intermediate layer was 0.6 μm.
ACR1: Bremer GLM, manufactured by NOF Corporation, a compound having the following structure.

(Formation of retardation layer)
On each intermediate layer, 1.8 g (1.62 g of B01 and 0.18 g of B02) of the two types of liquid crystal compounds shown below, 0.06 g of photopolymerization initiator (Irgacure 907, manufactured by Ciba Geigy Co., Ltd.) Sensitizer (Kayacure DETX, manufactured by Nippon Kayaku Co., Ltd.) 0.02 g, vertical alignment agent 0.002 g 9.2 g, acrylic compound (ACR3) 0.14 g, methyl ethyl ketone (MEK) / anone (= 90/10 The solution dissolved in (mass%) was applied with a wire bar of # 3.2. This was affixed to a metal frame and heated in a constant temperature bath at 100 ° C. for 2 minutes to align the rod-like liquid crystal compound. Next, using an air-cooled metal halide lamp (manufactured by Eye Graphics Co., Ltd.) with an oxygen concentration of about 0.1% under a nitrogen purge, ultraviolet rays with an illuminance of 190 mW / cm ² and an irradiation amount of 300 mJ / cm ² are used. Irradiated to cure the coating layer. Then, it stood to cool to room temperature.

(Vertical alignment agent)

(Acrylic compound ACR3)

  In this manner, laminated retardation films each having a retardation layer composed of a homeotropic liquid crystal layer on the intermediate layer were produced.

(Preparation of polarizing plate)
Each optical film 1 and 2 produced above is bonded using a polyvinyl alcohol polarizer and an adhesive, and similarly on the opposite surface of the polarizer, manufactured by Fuji Film Co., Ltd., Fujitac T40. Were bonded to each other to prepare polarizing plates. When laminating the retardation film and the polarizer, the surface of the cellulose acylate film as the support and the surface of the polarizer were laminated.
In addition, when mounting in a liquid crystal display device, the optical film was arrange | positioned between the liquid crystal cell and the polarizer in any case.

[Preparation of polarizing plate with adhesive layer]
(Formation of adhesive layer)
The pressure-sensitive adhesive layer composition used between each of the produced polarizing plates and the liquid crystal cell was used as a coating solution, applied to a separate film surface-treated with a silicone release agent using a die coater, and dried at 90 ° C. for 5 minutes. An acrylate-based pressure-sensitive adhesive layer was formed. The film thickness of the adhesive layer at that time was 15 μm.

(Transfer and aging of adhesive layer)
This pressure-sensitive adhesive layer was transferred to one side of each of the produced polarizing plates and aged for 7 days under the conditions of a temperature of 23 ° C. and a relative humidity of 65% to obtain a polarizing plate with a pressure-sensitive adhesive layer.

(Production of IPS liquid crystal display device)
Remove the liquid crystal panel from the new-iPad2 [Apple] equipped with the IPS mode liquid crystal cell, remove only the front side (upper side) of the optical film placed above and below the liquid crystal cell, and Washed.

The polarizing plate with each optical film was bonded to the display surface side surface of the said IPS mode liquid crystal cell, and the produced IPS liquid crystal display device was returned to the original housing | casing.
In this way, an IPS mode liquid crystal display device LCD was produced.

(Evaluation of IPS liquid crystal display device)
As a result of confirming the display performance in a state where the manufactured IPS liquid crystal display device is returned to the original housing and the backlight is turned on, the IPS liquid crystal display device having the optical film 2 having the cellulose acylate film 122 is in front contrast. The display performance with excellent color shift was obtained.

(Preparation of optical films 3 and 4)
An optical film 2 was prepared in the same manner as the optical films 1 and 2 except that the intermediate layer made of an acrylic layer was changed to an intermediate layer made of a polyvinyl alcohol (PVA) layer formed as follows, and a polarizing plate, An IPS liquid crystal display device was produced.

<Formation of intermediate layer (polyvinyl alcohol layer)>
100 parts by mass of a compound represented by the following general formula PVA (a = 85, b = 13, c = 2) and 5 parts by mass of T1 are 2.5% by mass in a solvent of water: methanol = 75: 25 mass ratio. A PVA layer-forming composition was prepared by dissolving in a solution. The solid content concentration of the intermediate layer forming composition was adjusted to 2% by mass. The intermediate layer forming composition was applied onto the cellulose acylate film 121 and the cellulose acylate film 122 by the wire bar coater # 8, and the intermediate layer was dried at 60 ° C. for 0.5 minutes. A film was formed.
The film thickness of the obtained intermediate layer was 0.3 μm.

The compounds used are shown below.

(Evaluation of IPS liquid crystal display device)
As a result of confirming the display performance of each manufactured IPS liquid crystal display device with the backlight turned on, the IPS liquid crystal display device having the optical film 4 having the cellulose acylate film 122 has excellent front contrast and color shift. Display performance was obtained.

Claims (12)

Including cellulose acylate having a total acyl substitution degree of 2.0 to 2.95 and an additive containing an aromatic, the film thickness is 10 to 45 μm, the internal haze is 0.10% or less, and the following formula ( A cellulose acylate film satisfying 1) to (3).
Formula (1) 40 nm ≦ Re (550) ≦ 150 nm
Formula (2) 80 nm ≦ Rth (550) ≦ 350 nm
Formula (3) 0.70 ≦ P_a / P_p ≦ 2.00
(In the formula, Re (550) represents in-plane retardation at a wavelength of 550 nm, Rth (550) represents retardation in the film thickness direction at a wavelength of 550 nm, P_p represents the degree of orientation of cellulose acylate, and P_a contains aromatics. Represents the degree of orientation of the additive. The cellulose acylate film according to claim 1, wherein the degree of orientation P_p of the cellulose acylate satisfies the following formula (3 ').
Formula (3 ′) P_p ≦ 0.15 The cellulose acylate film according to claim 1 or 2, wherein Nz represented by the following formula of the cellulose acylate film is 1.1 to 4.5.
Nz = Rth (550) / Re (550) +0.5 The cellulose acylate film according to any one of claims 1 to 3, wherein the substitution degree of the cellulose acylate is 2.0 to 2.6. The cellulose acylate film according to any one of claims 1 to 4, wherein the additive containing an aromatic is a polycondensed ester containing an aromatic and / or a sugar ester containing an aromatic. The cellulose acylate according to any one of claims 1 to 5, wherein a dimensional change rate after the cellulose acylate film is treated at 60 ° C and 90% relative humidity for 24 hours satisfies the following formulas (4) and (5). Rate film.
Formula (4) ΔL (MD) / L (MD)> 0.10%
Expression (5) ΔL (TD) / L (TD)> 0.30%
(Where L (MD) and L (TD) represent the longitudinal and lateral dimensions, respectively, before treatment for 24 hours at 60 ° C. and 90% relative humidity, ΔL (MD) and ΔL (TD) Represents the amount of dimensional change in the vertical and horizontal directions after treatment for 24 hours at 60 ° C. and 90% relative humidity, respectively. The cellulose acylate film according to claim 1, wherein the cellulose acylate film satisfies ΔRe (550) <− 5 nm and ΔRth (550) <− 5 nm.
ΔRe (550) is (retardation in the in-plane direction at a wavelength of 550 nm of the cellulose acylate film after being treated at 60 ° C. and 90% relative humidity for 24 hours) − (treated at 60 ° C. and 90% relative humidity for 24 hours) In-plane direction retardation at a wavelength of 550 nm of the previous cellulose acylate film);
ΔRth (550) is (retardation in the thickness direction at a wavelength of 550 nm of a cellulose acylate film after being treated at 60 ° C. and 90% relative humidity for 24 hours) − (treated at 60 ° C. and 90% relative humidity for 24 hours) Retardation in the thickness direction at a wavelength of 550 nm of the previous cellulose acylate film). The cellulose acylate film has a difference between the equilibrium moisture content by Karl Fischer method after immersion in pure water at 40 ° C. for 24 hours and the equilibrium moisture content by Karl Fischer method before immersion is less than 1.0%. Item 8. The cellulose acylate film according to any one of Items 1 to 7. An optical film having a retardation layer in which an alignment state of the cellulose acylate film and the liquid crystal material according to any one of claims 1 to 8 is fixed,
The retardation layer contains a liquid crystal compound that is homeotropically aligned,
An optical film in which the optical characteristics of the retardation layer satisfy the following formulas (1), (2), and (3).
80 ≦ Re ≦ 150 Formula (1)
−100 ≦ Rth ≦ 10 Formula (2)
0.05 ≦ | Rth / Re | ≦ 1.0 Formula (3) The optical film according to claim 9, comprising an intermediate layer containing a polyvinyl alcohol-based resin and / or an acrylic resin having a polar group between the cellulose acylate film and the retardation layer. A polarizing plate having a polarizer and the cellulose acylate film according to any one of claims 1 to 8 or the optical film according to claim 9 or 10 on at least one side of the polarizer. A liquid crystal display device comprising the polarizing plate according to claim 11 .

Images