JP2006044143A - Method for manufacturing oriented cellulose acylated film and oriented cellulose acylated film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a cellulose acylated film with excellent optical properties. <P>SOLUTION: In a process to orient the cellulose acylated film released from a support in a width direction by holding the width end part of the film, the orientation ratio (expansion ratio×100/maximum expansion ratio) is adjusted in accordance with a solvent residue of the cellulose acylated film. Also, the oriented cellulose acylated film is provided. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing a stretched cellulose acylate film useful for a liquid crystal image display device, and a stretched cellulose acylate film produced by the production method.

  Conventionally, a cellulose ester film is stretched and in-plane retardation (Re: hereinafter simply referred to as “Re”) and thickness direction retardation (Rth: hereinafter simply referred to as “Rth”). .) Is used, and this is used as a retardation film of a liquid crystal display device to increase the viewing angle. When the retardation film is used for an STN type liquid crystal display device, a large amount of Re and Rth are not required, and conventionally, a cellulose acetate film having 2-3 substitutions has been mainly used. However, in recent years, a vertical alignment (VA) liquid crystal display device has been developed, and a retardation film having higher Re and Rth is required. In order to cope with such a retardation film, a technique using a film obtained by casting a cellulose acylate film in which a propionyl group is substituted by 0.6 to 1.2 in addition to an acetyl group and casting the solution is proposed. (See Patent Document 1).

  In addition, as a method of casting a cellulose acylate in a solution and stretching the cellulose acylate film peeled off from the support in the width direction, a method using a tenter-type width stretching machine is generally used, and at the start of stretching A technique has been proposed in which the residual solvent amount is regulated to control the optical physical properties such as Re and Rth and the orientation angle distribution with respect to the longitudinal direction (see Patent Document 2).

On the other hand, in recent years, liquid crystal display devices are also provided with portability, and the opportunity to use them outdoors has increased. In addition, there are many uses that are installed in cars. For this reason, the durability of the liquid crystal display device under high temperature and high humidity has attracted particular attention. In view of the usage situation, the durability is such that Re, Rth, etc. to such an extent that the liquid crystal display function is impaired when the cellulose acylate film is exposed to an environment of 60 ° C. and 90% relative humidity for 1000 hours. It is necessary that the optical physical properties and the orientation angle distribution do not change.
However, when the above-mentioned cellulose acylate film is used, when exposed to an environment of 60 ° C. and 90% relative humidity for 1000 hours, the orientation angle distribution in the width direction of the cellulose acylate film changes, and light leakage and color unevenness occur. The liquid crystal display performance such as the above may be deteriorated, and improvement is necessary.

JP 2001-188128 A JP 2003-170492 A

  The present invention provides a method for producing a stretched cellulose acylate film that can be applied to a liquid crystal display device having good display performance even in a high-temperature and high-humidity environment, and a stretched cellulose acylate film produced by the production method.

As a result of voluntarily examining the production method for maintaining the orientation angle distribution in the width direction even in a high-temperature and high-humidity environment, the present inventor has cast a cellulose acylate solution on the support and evaporated a part of the solvent. Forming a cellulose acylate film, peeling the cellulose acylate film from the support, gripping the edge of the width, and then stretching in the width direction, the amount of residual solvent in the cellulose acylate film It turned out that this problem can be solved by adjusting a draw ratio according to a difference, and it came to this invention.
(1) A film forming step of casting a cellulose acylate solution on a support and evaporating a part of the solvent in the cellulose acylate solution to form a cellulose acylate film; and the cellulose acylate film as described above A peeling step for peeling from the support, and a stretching step for stretching the cellulose acylate film in the width direction,
In the stretching step, when the residual amount of the solvent represented by the following formula (1) of the cellulose acylate film after peeling from the support is 15% by mass, the following formulas (2), (3) and (4 The stretched cellulose acylate film is stretched in the width direction so that the stretch ratio represented by) is 10% to 90%.
Residual amount of solvent (% by mass) = (M−N) × 100 / N (1)
(M is the mass of the cellulose acylate film at the time of stretching, and N means the mass after drying the cellulose acylate film at 120 ° C. for 3 hours.)
Stretch ratio (%) = stretch ratio × 100 / maximum stretch ratio (2)
5% ≦ maximum stretching ratio ≦ 250% Formula (3)
Stretch ratio = [(width dimension after stretching in the width direction) − (width dimension in the unstretched state after peeling from the support)] × 100 / [in the unstretched state after peeling from the support] Width dimension] ... Formula (4)

(2) A stretched cellulose acylate film produced by the method for producing a stretched cellulose acylate according to (1).
(3) A polarizing plate comprising at least one layer of the stretched cellulose acylate film according to (2) above laminated on a polarizing layer.
(4) An optical compensation film for a liquid crystal display panel, wherein the stretched cellulose acylate film according to (2) is used as a substrate.
(5) An antireflection film using the stretched cellulose acylate film according to (2) as a substrate.

  The present invention relates to a method for producing a stretched cellulose acylate film suitable for use in a liquid crystal display device in which liquid crystal display performance such as light leakage and color unevenness does not deteriorate even when exposed to an environment of 60 ° C. and 90% relative humidity for 1000 hours, and The stretched cellulose acylate film produced by the production method is provided.

  Below, the manufacturing method of the stretched cellulose acylate film of this invention and a stretched cellulose acylate film are demonstrated in detail. The description of the constituent elements described below may be made based on representative examples of 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 the present invention, “Tg” indicates the glass transition temperature of cellulose acylate or film unless otherwise specified. Furthermore, in the present invention, the “stretched cellulose acylate film” means a cellulose acylate film after stretching.

  The method for producing a stretched cellulose acylate film of the present invention is a film formation in which a cellulose acylate solution is cast on a support and a part of the solvent in the cellulose acylate solution is evaporated to form a cellulose acylate film. And a peeling step of peeling the cellulose acylate film from the support, and a stretching step of stretching the cellulose acylate film in the width direction. The stretching step peeled off the support. When the residual amount of the solvent represented by the following formula (1) of the subsequent cellulose acylate film is 15% by mass, the stretch ratio represented by the following formulas (2), (3) and (4) is 10% to The film is stretched in the width direction so as to be 90%. Hereinafter, the method for producing a stretched cellulose acylate film of the present invention may be simply referred to as “the production method of the present invention”.

  The “orientation angle” in the present invention represents the direction of the slow axis in the plane of the cellulose acylate film (angle relative to the width direction during casting film formation), and is an automatic birefringence meter (trade name: KOBRA). -21ADH, a value measured with Oji Scientific Instruments). The orientation angle varies depending on the stretching conditions of the cellulose acylate film, but in order to obtain a good liquid crystal display image free from light leakage and color unevenness, the orientation angle distribution is preferably within ± 2 °, and within ± 1 °. Is more preferable, and most preferably within ± 0.5 °. Here, the “width direction” means the width direction with respect to the conveyance direction of the cellulose acylate film.

The “solvent residual amount” referred to in the present invention is a value satisfying the following formula (1).
Residual amount of solvent (% by mass) = (M−N) × 100 / N (1)
(M represents the mass of the cellulose acylate film at the time of stretching, and N represents the mass after drying the cellulose acylate film at 120 ° C. for 3 hours.)

In addition, the “stretch ratio” in the present invention is a value that satisfies the following formulas (2) and (3).
Stretch ratio (%) = stretch ratio × 100 / maximum stretch ratio (2)
5% ≦ maximum stretching ratio ≦ 250% Formula (3)
The “maximum stretch ratio” as used in the present invention is a value representing the stretch ratio when stretched to the maximum in the width direction in a state where the end of the width of the cellulose acylate film is gripped in the tenter.
The stretching ratio is a value that satisfies the following formula (4).
Stretch rate = [(width dimension after stretching in the width direction) − (width dimension in the unstretched state after peeling from the support) × 100 / (width in the unstretched state after peeling from the support) Hand dimensions] ... Formula (4)

  The point concerning the stretching of the cellulose acylate film in the present invention is that the above-mentioned problems are related to the residual solvent amount and the stretching ratio of the film, and the effect of the stretching ratio on the orientation angle distribution is different in a certain residual solvent amount. Thus, the factors involved in stretching are controlled. That is, in the production method of the present invention, when the residual amount of the solvent in the film peeled off from the support is 15% by mass, stretching is performed so that the stretching ratio is 10% to 90%. It was found that the stability over time at 60 ° C. and relative humidity 90% was excellent. More preferably, the stretching ratio is 15% to 90%, and most preferably 20% to 90% when the solvent residual amount is 15% by mass.

When the residual amount of the solvent is 15% by mass and the film is stretched at a stretch ratio of less than 1%, the cellulose acylate may break during the subsequent stretching. From the viewpoint of breaking, it is preferable to stretch in a state where the amount of residual solvent is large. If the stretching speed is lowered to avoid such a problem, productivity may be lowered, which is not preferable.
In addition, when the residual amount of the solvent is 15% by mass and the film is stretched in a state where the stretch ratio exceeds 90%, the cellulose acylate film is gradually relaxed during transportation, and the effect of stretching on Re and Rth is reduced. May end up. Further, in this case, the orientation angle distribution immediately after manufacture may exceed ± 2 °. For this reason, even if the orientation angle distribution immediately after manufacture satisfies ± 2 °, the orientation angle distribution exceeds ± 2 ° when exposed to high temperature and high humidity (60 ° C., relative humidity 90%) for 1000 hours. This is not preferable. If the residual solvent amount exceeds 250% by mass, when the cellulose acylate film is peeled off from the support, the cellulose acylate is not peeled off on the support and may not be stretched. For this reason, it is preferable that the solvent residual amount of the cellulose acylate film at the time of peeling of a peeling process is 250 mass% or less.

In addition, when the present inventor stretches to the maximum stretch rate, the time-dependent stability of the orientation angle distribution under high temperature and high humidity is better when the solvent residual amount in the film becomes relatively small. I found out. For this reason, the timing which extends | stretches a cellulose acylate film by the maximum extending | stretching rate in the manufacturing method of this invention is a case where the solvent residual amount of a cellulose acylate film is 0 mass%-15 mass%. In the production method of the present invention, it is preferable to stretch the solvent so that the residual amount of the solvent is 0% by mass to 10% by mass and the maximum stretching rate is 0% by mass to 5% by mass. Most preferably.
Although the mechanism related to such a phenomenon is not fully understood, the crystallinity of cellulose acylate molecules is increased by increasing the in-plane orientation under the balance between the in-plane orientation effect due to stretching and the effect of reducing in-plane orientation due to relaxation. Even when exposed to high temperature and high humidity (60 ° C., relative humidity 90%) for 1000 hours, the effect of orientation reduction due to relaxation is considered to be suppressed.

  The maximum stretching ratio is preferably 5% to 250%, more preferably 8% to 200%, and most preferably 10% to 150%. If the maximum stretching ratio is less than 5%, the effect of expressing Re and Rth by stretching may be small, which is not preferable. On the other hand, if it exceeds 250%, the orientation angle distribution may increase, and surface deterioration due to white turbidity or poor conveyance due to breakage may occur, which is not preferable.

  In the production method of the present invention, the film may be relaxed in the width direction while gripping the film after maximum stretching. The ratio of the width after relaxation to the width during maximum stretching (= width after relaxation × 100 / width during maximum stretching before relaxation) is not particularly limited as long as the orientation angle distribution is satisfied, but is 70% to 100%. Preferably, 80% to 100% is more preferable, and 90% to 100% is most preferable.

In the stretching step of the present invention, the residual amount of the solvent in the cellulose acylate film during stretching can be freely controlled by the temperature of the cellulose acylate film and the space temperature of the stretched portion.
The temperature of the cellulose acylate film in the stretching step is not particularly limited, but the temperature of the cellulose acylate film when stretched so that the stretch ratio is 1% to 90% is (Tg−150 ° C.) or more (Tg− Less than 10 ° C, more preferably Tg-130 ° C) or more and less than (Tg-10 ° C), and most preferably (Tg-110 ° C) or more and less than (Tg-10 ° C). Moreover, as a temperature of the temperature of the cellulose acylate film at the time of extending | stretching a cellulose acylate film by the maximum draw ratio, (Tg-10 degreeC)-(Tg + 50 degreeC) are preferable, (Tg-10 degreeC)-(Tg + 30 degreeC). ) Is more preferable, and (Tg−10 ° C.) to (Tg + 20 ° C.) is most preferable. Here, “Tg” represents the glass transition temperature of a film obtained by drying the cellulose acylate film to be used at 120 ° C. for 3 hours.

Moreover, the space temperature of the extending | stretching part (tenter) in an extending process is not specifically limited. Accordingly, the structure (number of zones) of the stretched part is not particularly limited, but the space temperature when stretching the cellulose acylate film so that the stretch ratio is 1% to 90% is (Tg-150 ° C.) to (Tg −10 ° C.) is preferable, (Tg−130) ° C. to (Tg−10) ° C. is more preferable, and (Tg−110 ° C.) to (Tg−10) ° C. is most preferable. Moreover, as space temperature at the time of extending | stretching a cellulose acylate film by the maximum extending | stretching rate, it is preferable that it is (Tg-10 degreeC)-(Tg + 50 degreeC), It is (Tg-10) degreeC- (Tg + 30 degreeC). Is more preferable, and (Tg−10 ° C.) to (Tg + 20 ° C.) is most preferable.
In the stretching step of the present invention, the stretched portion is preferably divided into at least two zones having different space temperatures. Moreover, when making the space temperature of an extending | stretching part constant, it is preferable that space temperature is (Tg-50 degreeC)-(Tg + 30 degreeC), and it is more preferable that it is (Tg-40 degreeC)-(Tg + 30 degreeC). Preferably, (Tg-30 ° C) to (Tg + 30 ° C) is most preferable. In this case, the extending portion may be a single zone or a plurality of extending portions as long as the space temperature is constant.

(Cellulose acylate film)
First, the cellulose acylate preferably used in the present invention will be described in detail. The cellulose acylate in the present invention is not particularly limited as long as the effects of the present invention are exhibited. In the present invention, two or more different cellulose acylates may be mixed and used. As the cellulose acylate that can be suitably used in the production method of the present invention, a cellulose acylate in which a hydroxyl group of cellulose is substituted with an acetyl group, and further an acyl group of 3 to 22 carbon atoms is substituted. Preferably, the following materials can be mentioned, for example. That is, it is preferable that the degree of substitution of the cellulose with a hydroxyl group satisfies the following formulas (I) to (III).
(I) 2.5 ≦ A + B ≦ 3.0
(II) 0 ≦ A ≦ 3.0
(III) 0 ≦ B ≦ 3.0
[In formula, A represents the substitution degree of the acetyl group substituted by the hydroxyl group of a cellulose, and B represents the substitution degree of the C3-C22 acyl group substituted by the hydroxyl group of a cellulose. ]

  The β-1,4-bonded glucose unit constituting cellulose has free hydroxyl groups at the 2nd, 3rd and 6th positions. Cellulose acylate is a polymer obtained by esterifying some or all of these hydroxyl groups with acyl groups. The degree of acyl substitution means the proportion of cellulose esterified at each of the 2-position, 3-position and 6-position (100% esterification has a degree of substitution of 1).

More preferably, the cellulose acylate satisfies the following formulas (Ia) to (IIIa) in terms of the degree of substitution of the cellulose with a hydroxyl group.
(Ia) 2.6 ≦ A + B ≦ 2.96
(IIa) 0 ≦ A ≦ 2.96
(IIIa) 0 ≦ B ≦ 2.96

Most preferably, the cellulose acylate satisfies the following formulas (Ib) to (IIIb) in terms of the degree of substitution of the cellulose with a hydroxyl group.
(Ib) 2.7 ≦ A + B ≦ 2.95
(IIb) 0 ≦ A ≦ 2.95
(IIIb) 0 ≦ B ≦ 2.95

  The acyl group (B) having 3 to 22 carbon atoms substituted on the hydroxyl group of cellulose acylate in the present invention may be an aliphatic group or an allyl group, and is not particularly limited. Examples of the acyl group (B) include cellulose alkylcarbonyl ester, alkenylcarbonyl ester, aromatic carbonyl ester, aromatic alkylcarbonyl ester, and the like, and each may further have a substituted group. These preferred acyl groups (B) include propionyl, butyryl, heptanoyl, hexanoyl, octanoyl, decanoyl, dodecanoyl, tridecanoyl, tetradecanoyl, hexadecanoyl, octadecanoyl, iso-butanoyl, t-butanoyl, cyclohexanecarbonyl Oleoyl, benzoyl, naphthylcarbonyl, cinnamoyl group and the like. Among these, propionyl, butyryl, pentanoyl, and hexanoyl are more preferable, and propionyl and butyryl are most preferable.

  The basic principle of the cellulose acylate synthesis method is described in Nobuhiko Umeda et al., Wood Chemistry, 180-190 (Kyoritsu Shuppan, 1968). A typical synthesis method of cellulose acylate is a liquid phase acylation method using a carboxylic acid anhydride-carboxylic acid-sulfuric acid catalyst. Specifically, cellulose raw materials such as cotton linter and wood pulp are pretreated with an appropriate amount of carboxylic acid such as acetic acid, and then put into a precooled acylated mixture for esterification, and complete cellulose acylate (2nd, The total degree of acyl substitution at the 3rd and 6th positions is approximately 3.00). The acylated mixed solution generally contains a carboxylic acid as a solvent, a carboxylic anhydride as an esterifying agent, and sulfuric acid as a catalyst. Carboxylic anhydride is usually used in a stoichiometric excess over the sum of the cellulose that reacts with it and the water present in the system. Further, after the acylation reaction is completed, water or hydrous acetic acid is added in order to hydrolyze the excess carboxylic anhydride remaining in the system. In order to partially neutralize the esterification catalyst, an aqueous solution of a neutralizing agent (for example, calcium, magnesium, iron, aluminum or zinc carbonate, acetate, hydroxide or oxide) may be added. Next, the obtained complete cellulose acylate is saponified and aged by maintaining it at 20 to 90 ° C. in the presence of a small amount of an acylation reaction catalyst (generally, remaining sulfuric acid) to obtain a desired degree of acyl substitution and polymerization. The cellulose acylate having a degree is changed. When the desired cellulose acylate is obtained, the catalyst remaining in the system is completely neutralized with a neutralizing agent as described above, or in water or dilute acetic acid without neutralization. Cellulose acylate can be obtained by charging the cellulose acylate solution (or adding water or dilute acetic acid into the cellulose acylate solution) to separate the cellulose acylate, and washing and stabilizing treatment.

  The viscosity average polymerization degree of the cellulose acylate preferably used in the present invention is preferably 150 to 500, more preferably 200 to 400, and particularly preferably 250 to 350. The viscosity-average polymerization degree can be measured by Uda et al.'S limiting viscosity method (Kazuo Uda, Hideo Saito, Journal of Textile Science, Vol. 18, No. 1, pages 105-120, 1962). Further details are described in JP-A-9-95538.

Such adjustment of the degree of polymerization can also be achieved by removing low molecular weight components in cellulose acylate. When the low molecular component in the cellulose acylate is removed, the average molecular weight (degree of polymerization) of the cellulose acylate is increased, but the viscosity is lower than that of ordinary cellulose acylate, which is useful. The removal of the low molecular component can be carried out by washing the cellulose acylate with an appropriate organic solvent.
Further, the molecular weight of the cellulose acylate can be adjusted by a polymerization method. For example, when manufacturing a cellulose acylate with few low molecular components, it is preferable to adjust the sulfuric acid catalyst amount in an acetylation reaction to 0.5-25 mass parts with respect to 100 mass of cellulose. When the amount of the sulfuric acid catalyst is within the above range, cellulose acylate that is preferable in terms of molecular weight distribution (uniform molecular weight distribution) can be synthesized.

The cellulose acylate used in the present invention preferably has a mass average molecular weight (Mw) / number average molecular weight (Mn) ratio of 1.5 to 5.5, more preferably 2.0 to 5.0. It is preferably 2.5 to 5.0, and most preferably 3.0 to 5.0.
As described above, only one type of cellulose acylate in the present invention may be used, or two or more types may be mixed. Moreover, what mixed suitably polymer components other than a cellulose acylate may be used. In this case, the polymer component to be mixed is preferably one having excellent compatibility with cellulose acylate. Further, the transmittance when the cellulose acylate in the present invention is used as a film is preferably 80% or more, more preferably 90% or more, and particularly preferably 92% or more.

  In the production method of the present invention, a cellulose acylate film once formed into a solution may be used by mixing with an unformed cellulose acylate. The ratio of the solution-forming cellulose acylate film contained in the total cellulose acylate is preferably 1% by mass to 50% by mass, more preferably 2% by mass to 45% by mass, and particularly preferably 3% by mass to 40% by mass. Once the cellulose acylate is formed into a solution, crystals are formed in the film and remain dissolved even if it is re-dissolved. When the film is formed again, it becomes a crystal nucleus and promotes crystal formation. For this reason, even if the cellulose acylate film formed by such a method is allowed to stand at high temperature and high humidity, it is considered that the orientation relaxation can be suppressed and the orientation angle distribution can be maintained. The formed cellulose acylate may be dissolved as it is, or may be dissolved after crushing. The latter is preferable in terms of increasing dissolution efficiency.

  The organic solvent for dissolving the cellulose acylate in the present invention is not particularly limited as long as the object can be achieved as long as the cellulose acylate can be dissolved and further cast and film-formed. As the organic solvent used for the dissolution, any of the following chlorine-based organic solvents and non-chlorine-based organic solvents can be used.

A) Chlorine organic solvent As the chlorine organic solvent, dichloromethane and chloroform are preferably mentioned, and dichloromethane is particularly preferred. In addition, there is no particular problem in mixing an organic solvent other than the chlorinated organic solvent with the chlorinated organic solvent. In that case, it is preferable to use at least 50% by mass of the chlorinated organic solvent such as dichloromethane. Examples of the chlorinated organic solvent that can be used in combination with the chlorinated organic solvent include non-chlorinated organic solvents.

  The non-chlorine organic solvent used in combination with the chlorinated organic solvent in the present invention will be described below. The preferred non-chlorine organic solvent is preferably a solvent selected from esters, ketones, ethers, alcohols, hydrocarbons, etc. having 3 to 12 carbon atoms. The ester, ketone, ether and alcohol may have a cyclic structure. A compound having two or more functional groups of the ester, ketone, and ether (that is, —O—, —CO—, and —COO—) can also be used as a solvent, such as an alcoholic hydroxyl group. You may have another functional group simultaneously. In the case of a non-chlorine organic solvent having two or more kinds of functional groups, the number of carbon atoms may be within the specified range of the compound having any functional group. Examples of esters having 3 to 12 carbon atoms include ethyl formate, propyl formate, pentyl formate, methyl acetate, ethyl acetate and pentyl acetate. Examples of ketones having 3 to 12 carbon atoms include acetone, methyl ethyl ketone, diethyl ketone, diisobutyl ketone, cyclopentanone, cyclohexanone, and methylcyclohexanone. Examples of the ether having 3 to 12 carbon atoms include diisopropyl ether, dimethoxymethane, dimethoxyethane, 1,4-dioxane, 1,3-dioxolane, tetrahydrofuran, anisole and phenetole. Examples of the organic solvent having two or more kinds of functional groups include 2-ethoxyethyl acetate, 2-methoxyethanol and 2-butoxyethanol.

Further, the alcohol used in combination with the chlorinated organic solvent may be linear, branched or cyclic, and among them, it is preferably a saturated aliphatic hydrocarbon.
The hydroxyl group of the alcohol may be any of primary to tertiary. Examples of the alcohol include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, t-butanol, 1-pentanol, 2-methyl-2-butanol and cyclohexanol. As the alcohol, a fluorine-based alcohol can also be used. Examples of the fluorinated alcohol include 2-fluoroethanol, 2,2,2-trifluoroethanol, 2,2,3,3-tetrafluoro-1-propanol, and the like.

  The hydrocarbon used in combination with the chlorinated organic solvent may be linear, branched or cyclic. As the hydrocarbon, either an aromatic hydrocarbon or an aliphatic hydrocarbon can be used. The aliphatic hydrocarbon may be saturated or unsaturated. Examples of the hydrocarbon include cyclohexane, hexane, benzene, toluene and xylene.

The non-chlorine organic solvent used in combination with the chlorinated organic solvent is not particularly limited. Among them, methyl acetate, ethyl acetate, methyl formate, ethyl formate, acetone, dioxolane, dioxane, ketones having 4 to 7 carbon atoms Or an acetoacetic ester, a C1-C10 alcohol, or a hydrocarbon is preferable. Specific examples of the non-chlorine organic solvent used in combination with the basic organic solvent include methyl acetate, acetone, methyl formate, ethyl formate, methyl ethyl ketone, cyclopentanone, cyclohexanone, methyl acetyl acetate, methanol, ethanol, 1 Mention may be made of -propanol, 2-propanol, 1-butanol, 2-butanol, and cyclohexanol, cyclohexane, hexane.
In the present invention, preferred combinations when a chlorinated organic solvent is used as the main solvent include the following. However, the present invention is not limited to these (numbers in parentheses below indicate parts by mass).

・ Dichloromethane / methanol (87.0 / 13.0)
・ Dichloromethane / methanol / butanol (81.6 / 14.8 / 3.6)
・ Dichloromethane / methanol / ethanol / butanol (80/10/5/5)
・ Dichloromethane / acetone / methanol / propanol (80/10/5/5)
・ Dichloromethane / methanol / butanol / cyclohexane (80/10/5/5)
・ Dichloromethane / methyl ethyl ketone / methanol / butanol (80/10/5/5)
・ Dichloromethane / acetone / methyl ethyl ketone / ethanol / isopropanol (75/10/5/5/5)
・ Dichloromethane / cyclopentanone / methanol / isopropanol (80/10/5/5)
・ Dichloromethane / methyl acetate / butanol (80/10/10)
・ Dichloromethane / cyclohexanone / methanol / hexane (70/20/5/5)
・ Dichloromethane / methyl ethyl ketone / acetone / methanol / ethanol (50/20/20/5/5)
・ Dichloromethane / 1,3 dioxolane / methanol / ethanol (70/20/5/5)
・ Dichloromethane / dioxane / acetone / methanol / ethanol (60/20/10/5/5)
・ Dichloromethane / acetone / cyclopentanone / ethanol / isobutanol / cyclohexane (65/10/10/5/5/5)
・ Dichloromethane / methyl ethyl ketone / acetone / methanol / ethanol (70/10/10/5/5)
・ Dichloromethane / acetone / ethyl acetate / ethanol / butanol / hexane (65/10/10/5/5/5)
・ Dichloromethane / methyl acetoacetate / methanol / ethanol (65/20/10/5)
・ Dichloromethane / cyclopentanone / ethanol / butanol (65/20/10/5)

B) Non-chlorine organic solvent When a non-chlorine organic solvent is used as the main solvent, the non-chlorine organic solvent is preferably a solvent selected from esters, ketones and ethers having 3 to 12 carbon atoms. The ester, ketone and ether may have a cyclic structure. A compound having two or more functional groups of the ester, ketone and ether (that is, —O—, —CO— and —COO—) can also be used as a main solvent. Such other functional groups may be included. In the case of the main solvent having two or more kinds of functional groups, the number of carbon atoms may be within the specified range of the compound having any functional group.

Examples of the esters having 3 to 12 carbon atoms include ethyl formate, propyl formate, pentyl formate, methyl acetate, ethyl acetate and pentyl acetate.
Examples of ketones having 3 to 12 carbon atoms include acetone, methyl ethyl ketone, diethyl ketone, diisobutyl ketone, cyclopentanone, cyclohexanone, and methylcyclohexanone.
Examples of ethers having 3 to 12 carbon atoms include diisopropyl ether, dimethoxymethane, dimethoxyethane, 1,4-dioxane, 1,3-dioxolane, tetrahydrofuran, anisole and phenetole.
Examples of the organic solvent having two or more kinds of functional groups include 2-ethoxyethyl acetate, 2-methoxyethanol and 2-butoxyethanol.

  Furthermore, as a preferable solvent used when dissolving cellulose acylate in the present invention, three or more different mixed solvents can be used. As a combination of the mixed solvents, it is preferable to combine the following first to third solvents. Examples of the first solvent include at least one selected from methyl acetate, ethyl acetate, methyl formate, ethyl formate, acetone, dioxolane, and dioxane, or a mixed solution thereof. Examples of the second solvent include ketones having 4 to 7 carbon atoms or acetoacetate. Furthermore, as a 3rd solvent, a C1-C10 alcohol or hydrocarbon is mentioned. As this 3rd solvent, a C1-C8 alcohol is preferable. Note that when the first solvent is a mixture of two or more solvents, the second solvent may not be used.

  As the first solvent, methyl acetate, acetone, methyl formate, ethyl formate, or a mixture thereof is more preferable. The second solvent is preferably methyl ethyl ketone, cyclopentanone, cyclohexanone, or methyl acetyl acetate, and may be a mixture thereof.

  The alcohol as the third solvent may be linear, branched or cyclic, and is preferably a saturated aliphatic hydrocarbon. The hydroxyl group of the alcohol may be any of primary to tertiary. Examples of the alcohol include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, t-butanol, 1-pentanol, 2-methyl-2-butanol and cyclohexanol. In addition, a fluorine-type alcohol can also be used as said alcohol. Examples of the fluorinated alcohol include 2-fluoroethanol, 2,2,2-trifluoroethanol, 2,2,3,3-tetrafluoro-1-propanol, and the like.

  Further, the hydrocarbon as the third solvent may be linear, branched or cyclic. In addition, both aromatic hydrocarbons and aliphatic hydrocarbons can be used. The aliphatic hydrocarbon may be saturated or unsaturated. Examples of the hydrocarbon include cyclohexane, hexane, benzene, toluene and xylene.

  These alcohols and hydrocarbons used as the third solvent may be used alone or as a mixture of two or more. Preferable specific examples of the third solvent include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, and cyclohexanol, cyclohexane, hexane, and particularly methanol, ethanol, 1 -Propanol, 2-propanol and 1-butanol are preferred.

The three types of mixed solvents preferably include a first solvent in a ratio of 20 to 95% by mass, a second solvent in a ratio of 2 to 60% by mass, and a third solvent in a ratio of 2 to 30% by mass. It is preferable that the first solvent is 30 to 90% by mass, the second solvent is 3 to 50% by mass, and further the third alcohol is 3 to 25% by mass. Moreover, it is especially preferable that the 1st solvent is 30-90 mass%, the 2nd solvent is 3-30 mass%, and the 3rd solvent is alcohol and 3-15 mass% is contained. In addition, when using a liquid mixture as a 1st solvent and not using a 2nd solvent, the 1st solvent is 20-90 mass%, and the 3rd solvent is contained in the ratio of 5-30 mass%. The first solvent is preferably 30 to 86% by mass, and the third solvent is further preferably 7 to 25% by mass.
The non-chlorine organic solvent used in the present invention is described in more detail in pages 12 to 16 of the Japan Society for Invention and Technology (public technical number 2001-1745, published on March 15, 2001, Japan Society for Invention). It is described in detail.

Preferred combinations of non-chlorine organic solvents of the present invention include the following combinations. However, the present invention is not limited to these (numbers in parentheses indicate parts by mass).
・ Methyl acetate / acetone / methanol / ethanol / butanol (75/10/5/5/5)
・ Methyl acetate / acetone / methanol / ethanol / propanol (75/10/5/5/5)
・ Methyl acetate / acetone / methanol / butanol / cyclohexane (75/10/5/5/5)
・ Methyl acetate / acetone / ethanol / butanol (81/8/7/4)
・ Methyl acetate / acetone / ethanol / butanol (82/10/4/4)
・ Methyl acetate / acetone / ethanol / butanol (80/10/4/6)
・ Methyl acetate / methyl ethyl ketone / methanol / butanol (80/10/5/5)
・ Methyl acetate / acetone / methyl ethyl ketone / ethanol / isopropanol (75/10/5/5/5)
・ Methyl acetate / cyclopentanone / methanol / isopropanol (80/10/5/5)
・ Methyl acetate / acetone / butanol (85/10/5)
・ Methyl acetate / cyclopentanone / acetone / methanol / butanol (60/15/15/5/5)
・ Methyl acetate / cyclohexanone / methanol / hexane (70/20/5/5)
・ Methyl acetate / methyl ethyl ketone / acetone / methanol / ethanol (50/20/20/5/5)
・ Methyl acetate / 1,3 dioxolane / methanol / ethanol (70/20/5/5)
・ Methyl acetate / dioxane / acetone / methanol / ethanol (60/20/10/5/5)
・ Methyl acetate / acetone / cyclopentanone / ethanol / isobutanol / cyclohexane (65/10/10/5/5/5)
・ Methyl formate / methyl ethyl ketone / acetone / methanol / ethanol (50/20/20/5/5)
・ Methyl formate / acetone / ethyl acetate / ethanol / butanol / hexane (65/10/10/5/5/5)
Acetone / methyl acetoacetate / methanol / ethanol (65/20/10/5)
Acetone / cyclopentanone / ethanol / butanol (65/20/10/5)
Acetone / 1,3 dioxolane / ethanol / butanol (65/20/10/5)
・ 1,3 dioxolane / cyclohexanone / methyl ethyl ketone / methanol / butanol (60/20/10/5/5)

Furthermore, as described below, it is also preferable to add a part of the solvent after dissolution and dissolve in multiple stages (the numbers in parentheses indicate parts by mass).
-Prepare a cellulose acylate solution with methyl acetate / acetone / ethanol / butanol (81/8/7/4), add 2 parts by weight of butanol after filtration and concentration-Methyl acetate / acetone / ethanol / butanol (84 / 10/4/2) to prepare a cellulose acylate solution, and after filtration and concentration, add 4 parts by weight of butanol additionally. Prepare a cellulose acylate solution with methyl acetate / acetone / ethanol (84/10/6). Add 5 parts by weight of butanol after filtration and concentration

  Regarding the preparation of the cellulose acylate solution (dope) in the present invention, the dissolution method is not particularly limited, and may be room temperature, and further, a cooling dissolution method or a high temperature dissolution method, and further a combination thereof. With respect to these, for example, JP-A-61-106628, JP-A-58-127737, JP-A-2-276830, JP-A-4-259511, JP-A-5-163301, and JP-A-9 JP-A-10-95544, JP-A-10-67860, JP-A-10-95854, JP-A-10-45950, JP-A-2000-53784, JP-A-10-324774, JP-A-11-71463. No. 11-302388, No. 11-322946, No. 11-322947, No. 11-323017, No. 2000-273239, No. 2000-273184 Describes a method for preparing a cellulose acylate solution. The above-described methods for dissolving cellulose acylate in an organic solvent can be applied to these techniques within the scope of the present invention. The details of these are described in detail on pages 22 to 25 of the non-chlorine-based solvent system in the Japan Society for Invention and Technology (Publication No. 2001-1745, published on March 15, 2001, Japan Society for Invention). Be implemented in a way that

  Furthermore, the cellulose acylate solution in the present invention is usually subjected to solution concentration and filtration. Similarly, these are also described in detail on page 25 in the Japan Society of Invention Disclosure Technical Bulletin (Public Technical Number 2001-1745, published on March 15, 2001, Invention Association). In addition, when cellulose acylate is dissolved at a high temperature, it is almost the boiling point of the organic solvent used, and in that case, it is used in a pressurized state.

In the production method of the present invention, it is preferable that 10 to 35% by mass of cellulose acylate is dissolved in the solvent, and 13 to 33% by mass is dissolved in any of the chlorinated and non-chlorinated organic solvents. Is more preferable, and 15 to 30% by mass is most preferable. The method for adjusting the cellulose acylate solution to these concentrations may be carried out so that the cellulose acylate solution has a predetermined concentration at the stage of dissolution, or is prepared in advance as a low concentration solution (for example, 9 to 14% by mass) and then concentrated. A process may be provided and adjusted to a predetermined high-concentration solution at a concentration temperature or a concentration time.
Prior to dissolution, it is preferable to dry the cellulose acylate after film formation and after film formation so that the moisture content is 2% by mass or less, more preferably 1% by mass or less.
Furthermore, it is preferable to swell the cellulose acylate at 0 ° C. to 50 ° C. for 0.1 hour to 100 hours after mixing these cellulose acylate and solvent.

  In the cellulose acylate solution of the present invention, various additives (for example, peeling accelerators, plasticizers, ultraviolet inhibitors, infrared absorbers, fine particles, deterioration inhibitors, optically anisotropic) according to the use in each preparation step. Sex control agents, release agents, etc.) can be added. The additive may be solid or oily. That is, the melting point and boiling point are not particularly limited. These additives may be added before the swelling step when dissolving the cellulose acylate, or may be added during or after the swelling step. Furthermore, it may be during or after cooling.

As said peeling promoter, it is preferable that pKa is 1.0-5.0, and it is more preferable that it is 1.5-4.5. Cellulose acylate has substituents such as COOCa and OSO ₃ Ca derived from the synthesis method, and the substituent Ca increases the peeling load by interacting with oxygen atoms on the surface of the support. Yes. For this reason, by adding a peeling accelerator having a pKa in the above range and changing the substituent of cellulose acylate from COOCa to COOH, the interaction between the cellulose acylate and the support can be weakened, and the peeling load Can be reduced.
The amount of the peeling accelerator used is preferably 1 ppm to 4000 ppm, more preferably 5 ppm to 3000 ppm, and most preferably 10 ppm to 2500 ppm with respect to cellulose acylate. If the amount of the release agent used exceeds 4000 ppm, the amount of the release accelerator that evaporates during the drying process of the cellulose acylate film increases, and the release accelerator that has cooled to become droplets falls onto the film to form a planar shape. It may be worsened or the production system may be contaminated, which is not preferable. If it is less than 1 ppm, there is almost no effect on the peeling load, and the productivity tends to be insufficient.

  The release accelerator is preferably at least one release accelerator selected from phosphoric acid esters, sulfonic acids, and acids having an acid dissociation constant pKa of 1.0 to 5.0 or salts thereof. Examples of the peeling accelerator include formic acid, acetic acid, lactic acid, benzoic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, glucholic acid, malic acid, suberic acid, tartaric acid, citric acid, and salts thereof. Glucolic acid, lactic acid, malic acid, tartaric acid, citric acid and salts thereof are preferable.

As the plasticizer, for example, those described in JP-A No. 2000-352620 can be used. From the viewpoint of reducing Re and Rth changes under high humidity, preferred examples of the plasticizer include alkylphthalylalkyl glycolates, phosphate esters, and carboxylate esters. Examples of the alkyl phthalyl alkyl glycolates include methyl phthalyl methyl glycolate, ethyl phthalyl ethyl glycolate, propyl phthalyl propyl glycolate, butyl phthalyl butyl glycolate, octyl phthalyl octyl glycolate, and methyl phthalate. Ruethyl glycolate, ethyl phthalyl methyl glycolate, ethyl phthalyl propyl glycolate, methyl phthalyl butyl glycolate, ethyl phthalyl butyl glycolate, butyl phthalyl methyl glycolate, butyl phthalyl ethyl glycolate, propyl phthalyl Butyl glycolate, butyl phthalyl propyl glycolate, methyl phthalyl octyl glycolate, ethyl phthalyl octyl glycolate, octyl phthalyl methyl glycolate, octyl Tali ethyl glycolate, and the like.
Examples of the phosphate ester include triphenyl phosphate, tricresyl phosphate, phenyl diphenyl phosphate, and the like.
Examples of the carboxylic acid ester include phthalic acid esters such as dimethyl phthalate, diethyl phthalate, dibutyl phthalate, dioctyl phthalate, and diethylhexyl phthalate; citrate esters such as acetyl trimethyl citrate, acetyl triethyl citrate, and acetyl tributyl citrate. There can be mentioned.
In addition, as the plasticizer, butyl oleate, methylacetyl ricinoleate, dibutyl sebacate, triacetin or the like is preferably used alone or in combination.

  The amount of these plasticizers to be used is preferably 0% by mass to 15% by mass, more preferably 0% by mass to 10% by mass, and particularly preferably 0% by mass to 8% by mass with respect to cellulose acylate. These plasticizers may be used in combination of two or more if necessary.

Examples of the ultraviolet light inhibitor include those described in JP-A No. 2001-151901. Moreover, as said infrared absorber, the thing of Unexamined-Japanese-Patent No. 2001-194522 can be used, for example, It is preferable to make it contain 0.001-5 mass% with respect to a cellulose acylate, respectively.
As the fine particles, those having an average particle diameter of 5 to 3000 nm are preferably used. As the fine particles, those composed of a metal oxide or a crosslinked polymer can be used, and it is preferable to contain 0.001 to 5% by mass with respect to cellulose acylate.
Examples of the deterioration preventing agent include those described in JP-A-5-194789 and JP-A-6-107854, and it is preferable to contain 0.0001 to 2% by mass with respect to cellulose acylate. Moreover, as said optical anisotropy control agent, the thing of Unexamined-Japanese-Patent No. 2003-66230, Unexamined-Japanese-Patent No. 2002-49128 can be used, for example, 0.1-15 mass% containing with respect to a cellulose acylate It is preferable to make it.

  These various additives may be added at any time during the preparation of the cellulose acylate solution (dope preparation step), but at the end of the dope preparation step, the additive is added and the preparation step is performed. May be. Furthermore, the addition amount of each raw material is not particularly limited as long as the function is manifested.

(Method for producing stretched cellulose acylate film)
As a method and equipment for forming a stretched cellulose acylate film in the present invention, a solution casting film forming method and a solution casting film forming apparatus used for producing a conventional cellulose acylate film can be used. About each manufacturing process, it is described in invention association, invention association public technical bulletin, public technical number 2001-1745, 25-30 pages (March 15, 2001), casting (including co-casting), metal support It is classified into body, drying, peeling and stretching.
Hereinafter, a specific implementation method of the present invention will be described according to a procedure.

-Film formation process-
The film forming step is a step of casting a cellulose acylate solution on a support and evaporating the solvent in the cellulose acylate solution to form a cellulose acylate film.
Specifically, first, a cellulose acylate solution (hereinafter sometimes referred to as “dope”) prepared from a dissolving machine (pot) is temporarily stored in a storage pot, filtered, and contained in the dope. Defoam the foam to make the final preparation. Next, the dope is fed from the dope discharge port to the pressure die through a pressure metering gear pump that can deliver the metered liquid with high accuracy, for example, by the number of revolutions, and is cast endlessly from the die (slit) of the pressure die. Cast uniformly on the metal support of the part. The casting may be a single layer casting, or two or more types of cellulose acylate solutions may be simultaneously and / or sequentially co-cast. When the casting process includes two or more layers, the types and concentrations of the dope cellulose acylate, the solvent, and the additive in each layer may be the same or different.

  The space temperature of the casting part is not particularly limited, but is preferably −110 ° C. to + 90 ° C., more preferably −100 ° C. to + 80 ° C., and most preferably −90 ° C. to + 70 ° C. . In particular, a cellulose acylate solution cast at a low space temperature is instantaneously cooled on a metal support to increase the gel strength, so that a film containing the organic solvent can be held. Thereby, it is possible to peel off from the metal support in a short time without evaporating the organic solvent from the cellulose acylate, and high-speed casting can be achieved. In addition, as a means for cooling the casting part (space), normal air may be used, or a gas such as nitrogen, argon, helium or the like may be used. Further, the humidity during casting is preferably 0 to 70% relative humidity, and more preferably 0 to 50% relative humidity.

  Furthermore, the temperature of the metal support in the casting part (the temperature of the film-forming surface of the metal support) is not particularly limited, but is preferably −50 ° C. to 80 ° C., and preferably −30 ° C. to 50 ° C. More preferably, it is most preferably -20 ° C to 25 ° C. In order to keep the casting part at a preferable temperature in the present invention, it may be achieved by introducing a cooled gas into the casting part, or a cooling device is arranged in the casting part to cast the casting part (space). May be cooled. At this time, it is important to pay attention so that water does not adhere, and it is preferable to carry out the method by using a dry gas.

-Peeling process-
The peeling process in this invention is a process of peeling the cellulose acylate film formed on a support body from this support body. In the peeling step, the point where the metal support that is running endlessly in the casting part has made one round can be set as the peeling point, and at this peeling point, the dry cellulose acylate film (also referred to as web) is used as the support. Peel from.
In the present invention, when the dry cellulose acylate film (web) is peeled off from the metal support, the amount of residual solvent in the cellulose acylate film is preferably more than 10% by mass and less than 250% by mass, preferably 15% by mass to 230 mass% is still more preferable, and 20 mass%-220 mass% is the most preferable. When the residual solvent amount is 250% by mass or more, the cellulose acylate may not peel off on the support. If it is less than 10% by mass, the gel strength of the cellulose acylate increases, and it becomes impossible to follow the curvature of the rotating metal support, and the cellulose acylate film moves away from the support when it moves under the support. It may fall and cause poor conveyance.

-Stretching process-
The stretching step in the present invention is a step of stretching a cellulose acylate film obtained by peeling from a support in the width direction. In the stretching step, for example, the both ends of the cellulose acylate film are gripped, while being stretched in the width direction, transported with a tenter and dried, and subsequently transported with a roll group of a drying device, and drying is completed. It winds up to predetermined length with a winder. The combination of the tenter and the roll group drying apparatus can be changed depending on the purpose. In the solution casting film forming method used for silver halide photographic light-sensitive materials and functional protective films for electronic displays, in addition to the solution casting film forming apparatus, an undercoat layer, an antistatic layer, an antihalation layer, a protective layer, etc. In many cases, a coating apparatus is added to the surface processing of the film.
The orientation angle distribution of the stretched cellulose acylate film (stretched cellulose acylate film) is preferably within ± 2 °, more preferably within ± 1 °, and within ± 0.5 °. Is most preferred.

In the present invention, it is preferable that Re and Rth of the cellulose acylate film before and after stretching satisfy the following formula.
Rth ≧ Re
200 ≧ Re ≧ 0
500 ≧ Rth ≧ −100

Moreover, it is more preferable to satisfy the following formula.
Rth ≧ Re × 1.1
150 ≧ Re ≧ 10
400 ≧ Rth ≧ −80

Furthermore, it is particularly preferable that the following formula is satisfied.
Rth ≧ Re × 1.2
100 ≧ Re ≧ 20
350 ≧ Rth ≧ −60

In the present invention, Re and Rth are represented by the following formulas.
Re (nm) = | nx−ny | × d
Rth (nm) = | {(nx + ny) / 2} −nz | × d
(Where, nx, ny, and nz represent the refractive index in the film forming direction, the width direction, and the thickness direction, respectively, and d represents the thickness (nm).)

  The thickness of the cellulose acylate film before and after stretching is preferably 20 μm to 300 μm, more preferably 30 μm to 250 μm, and most preferably 40 μm to 200 μm. The thickness unevenness of the cellulose acylate film is preferably 0% to 2% in both the thickness direction and the width direction, both unstretched and after stretching, more preferably 0% to 1.5%, and more preferably 0% Most preferred is ˜1%.

In the stretching step of the present invention, the cooling method after completion of drying and after stretching is not particularly limited, but from the viewpoint of suppressing the change over time of the orientation angle distribution of the stretched cellulose acylate film under high temperature and high humidity, It is preferable to slow down the cooling rate after stretching.
Moreover, it is predicted that the in-plane orientation is reduced due to relaxation due to moisture absorption as a cause of the change in the orientation angle distribution with time. As a method for suppressing the reduction of the in-plane orientation, a method of reducing the gap (free volume) between cellulose acylate molecules is effective. In this method, it is preferable to slow down the cooling rate after completion of drying and after stretching, and the cooling rate between the outlet temperature of the drying zone and the stretching zone to 50 ° C. is 2 ° C./min to 60 ° C./min. It is preferably 3 ° C / min to 40 ° C / min, more preferably 4 ° C / min to 30 ° C / min. Usually, cooling is performed at a cooling rate of 100 ° C./min or more from the outlet temperature to 50 ° C., so that the above-mentioned conditions cool down fairly slowly.

Cellulose acylate film shrinks in volume with cooling, but when the glass transition temperature (Tg) is exceeded, the mobility of cellulose acylate molecules decreases rapidly, so the shrinkage of the molecule cannot catch up with the cooling rate, and the free volume is reduced. Easy to grow. For this reason, it is considered that the humidity change of the orientation angle distribution can be reduced by slow cooling as described above and reducing the free volume.
Such cooling from Tg to Tg is likely to occur after drying and stretching, and in this case, it is necessary to gradually cool as described above. The slow cooling may be carried out in any manner, and can be achieved, for example, by dividing the outlet of the heat treatment zone into several parts and cooling it stepwise to room temperature. It can also be carried out by blowing temperature-controlled air at the heat treatment zone outlet or by providing a heat source (for example, an infrared heater, a halogen heater, a panel heater, etc.).

-Winding process-
In the manufacturing method of this invention, after making it dry with the above-mentioned method, both ends can be trimmed, a die-pressing process (knurling provision) can be provided, and the winding-up process which winds it can be provided. The residual solvent in the stretched cellulose acylate film thus dried is preferably 0% to 5%, more preferably 0% to 2%, still more preferably 0% to 1%. After drying, trim both ends and wind up. A preferable width is 0.5 m to 5 m, more preferably 0.7 m to 3 m, and still more preferably 1 m to 2 m. The preferred winding length is 300 m to 30000 m, more preferably 500 m to 10000 m, and still more preferably 1000 m to 7000 m.

-Surface treatment-
In the production method of the present invention, an unstretched or stretched cellulose acylate film is subjected to a surface treatment as necessary, and the cellulose acylate film is adhered to each functional layer (for example, an undercoat layer and a back layer). It is possible to improve the performance. As the surface treatment, for example, glow discharge treatment, ultraviolet irradiation treatment, corona treatment, flame treatment, acid or alkali treatment can be used. The “glow discharge treatment” here is a treatment for subjecting the film surface to a plasma treatment in the presence of a plasma-excitable gas. The glow discharge treatment may be low-temperature plasma that occurs in a low-pressure gas of 10 ^{−3 to} 20 Torr (0.13 to 2700 Pa), and plasma treatment under atmospheric pressure is also preferable. The plasma-excitable gas refers to a gas that is plasma-excited under the above-described conditions, for example, chlorofluorocarbons such as argon, helium, neon, krypton, xenon, nitrogen, carbon dioxide, tetrafluoromethane, and their A mixture etc. are mentioned.
Details of these are described in detail in pages 30 to 32 in the Japan Institute of Invention Disclosure Technical Bulletin (Public Technical Number 2001-1745, published on March 15, 2001, Invention Association). Note that the plasma treatment at atmospheric pressure that has been attracting attention in recent years is preferably, for example, irradiation energy of 20 to 500 kGy under 10 to 1000 kEv, and more preferably irradiation energy of 20 to 300 kGy under 30 to 500 kEv. . Among these surface treatments, the alkali saponification treatment is particularly preferable, and is extremely effective as the surface treatment of the cellulose acylate film.

The alkali saponification treatment may be immersed in a saponification solution (immersion method) or a saponification solution may be applied (application method). In the case of the immersion method, an aqueous solution having a pH of 10 to 14 such as NaOH or KOH is passed through a bath heated to 20 to 80 ° C. for 0.1 to 10 minutes, and then neutralized, washed with water, and dried. Can be achieved.
In the case of the coating method, a dip coating method, a curtain coating method, an extrusion coating method, a bar coating method, and an E-type coating method can be used. The solvent of the alkali saponification coating solution has good wettability because it is applied to the transparent support of the saponification solution, and the surface state remains good without forming irregularities on the surface of the transparent support by the saponification solution solvent. It is preferred to select a solvent to keep. Specifically, an alcohol solvent is preferable, and isopropyl alcohol is particularly preferable.
An aqueous solution of a surfactant can also be used as a solvent. The alkali of the alkali saponification coating solution is preferably an alkali that dissolves in the solvent, and for example, KOH and NaOH are more preferable. The pH of the saponification coating solution is preferably 10 or more, and more preferably 12 or more. The reaction conditions during alkali saponification are preferably 1 second to 5 minutes at room temperature, more preferably 5 seconds to 5 minutes, and most preferably 20 seconds to 3 minutes. After the alkali saponification reaction, it is preferable to wash the surface on which the saponification solution is applied with water or with an acid and then with water. Also, the coating-type saponification treatment and the alignment film uncoating described later can be performed continuously, and the number of steps can be reduced. Specific examples of these saponification methods include the contents described in JP-A-2002-82226 and International Publication WO02 / 46809.

Moreover, it is also preferable to pass through the undercoat process which provides an undercoat layer for adhesion | attachment with a functional layer. This layer may be applied after the surface treatment or may be applied without the surface treatment. Details of the undercoat layer are described on page 32 of the Japan Society for Invention and Innovation (Public Technical Number 2001-1745, published on March 15, 2001, Japan Institute of Invention).
These surface treatments and the undercoating process for forming the undercoating layer can be incorporated at the end of the film forming process (film forming process), can be performed alone, or performed in the functional layer application process described later. You can also.

-Addition of functional layer-
Functionality described in detail on pages 32 to 45 of the stretched cellulose acylate film of the present invention in the technical report of the Japan Society of Invention (Public Technical Number 2001-1745, published on March 15, 2001, Japan Society of Invention). It is preferred to combine the layers. Among these, application of a polarizing layer (polarizing plate), application of an optical compensation layer (optical compensation sheet for liquid crystal display plate), and application of an antireflection layer (antireflection film) are preferable.
(1) Application of polarizing layer (preparation of polarizing plate)
[Material used]
Currently, a commercially available polarizing layer is generally prepared by immersing a stretched polymer in a solution of iodine or dichroic dye in a bath and allowing the iodine or dichroic dye to penetrate into the binder. It is. The polarizing layer is manufactured by Optiva Inc. A coating type polarizing film typified by can also be used. Iodine and dichroic dye in the polarizing layer exhibit deflection performance by being oriented in the binder. As the dichroic dye, an azo dye, stilbene dye, pyrazolone dye, triphenylmethane dye, quinoline dye, oxazine dye, thiazine dye or anthraquinone dye is used. The dichroic dye is preferably water-soluble. The dichroic dye preferably has a hydrophilic substituent (eg, sulfo, amino, hydroxyl). For example, the compound as described in Invention Association public technique, public technical number 2001-1745, page 58 (issue date March 15, 2001) can be mentioned.

  As the binder for the polarizing layer, either a polymer that can be crosslinked by itself or a polymer that is crosslinked by a crosslinking agent can be used, and a plurality of combinations thereof can be used. Examples of the binder include methacrylate copolymer, styrene copolymer, polyolefin, polyvinyl alcohol and modified polyvinyl alcohol, poly (N-methylolacrylamide) described in paragraph No. [0022] of JP-A-8-338913. , Polyester, polyimide, vinyl acetate copolymer, carboxymethyl cellulose, polycarbonate and the like. Moreover, a silane coupling agent can be used as a polymer. The binder is preferably a water-soluble polymer (eg, poly (N-methylolacrylamide), carboxymethylcellulose, gelatin, polyvinyl alcohol, modified polyvinyl alcohol), more preferably gelatin, polyvinyl alcohol, and modified polyvinyl alcohol, and polyvinyl alcohol and modified. Polyvinyl alcohol is most preferred. Furthermore, it is particularly preferable to use two types of polyvinyl alcohol or modified polyvinyl alcohol having different degrees of polymerization. The saponification degree of polyvinyl alcohol is preferably 70 to 100%, and more preferably 80 to 100%. It is preferable that the polymerization degree of polyvinyl alcohol is 100-5000. The modified polyvinyl alcohol is described in JP-A-8-338913, 9-152509 and 9-316127. Two or more kinds of polyvinyl alcohol and modified polyvinyl alcohol may be used in combination.

In the polarizing layer, the lower limit of the binder thickness is preferably 10 μm. The upper limit of the thickness is preferably as thin as possible from the viewpoint of light leakage of the liquid crystal display device. For example, it is preferably not more than a commercially available polarizing plate (about 30 μm), preferably 25 μm or less, and more preferably 20 μm or less.
The binder of the polarizing layer may be cross-linked. For this reason, the polymer and monomer which have a crosslinkable functional group may be mixed in a binder, and a crosslinkable functional group may be provided to binder polymer itself. Crosslinking can be performed by light, heat, or pH change, whereby a binder having a crosslinked structure can be formed. The crosslinking agent is described in US Reissue Patent 23297. Boron compounds (eg, boric acid, borax) can also be used as a crosslinking agent. The addition amount of the crosslinking agent in the binder is preferably 0.1 to 20% by mass with respect to the binder. The orientation of the polarizing element and the moisture and heat resistance of the polarizing layer are improved.
Even after the crosslinking reaction is completed, the unreacted crosslinking agent is preferably 1.0% by mass or less, more preferably 0.5% by mass or less. By doing in this way, a weather resistance improves.

[Stretching of polarizing layer]
The polarizing layer is preferably dyed with iodine or a dichroic dye after stretching the polarizing film (stretching method) or rubbing (rubbing method).
In the stretching method, the stretching ratio is preferably 2.5 to 30.0 times, and more preferably 3.0 to 10.0 times. Stretching can be performed by dry stretching in air. Moreover, you may implement wet extending | stretching in the state immersed in water. The stretch ratio of dry stretching is preferably 2.5 to 5.0 times, and the stretch ratio of wet stretching is preferably 3.0 to 10.0 times. Stretching may be performed in parallel to the MD direction (parallel stretching), or may be performed in an oblique direction (oblique stretching). These stretching operations may be performed once or divided into several times. By dividing into several times, it is possible to stretch more uniformly even at high magnification. A more preferred stretching method is oblique stretching in which the film is stretched with an inclination of 10 ° to 80 ° in the oblique direction.

(A) Parallel stretching method Prior to stretching, it is preferable to swell the PVA film. At this time, the degree of swelling is 1.2 to 2.0 times (mass ratio between before swelling and after swelling). Thereafter, it is preferably stretched at a bath temperature of 15 to 50 ° C., especially 17 to 40 ° C. in an aqueous medium bath or a dye bath for dissolving a dichroic substance while being continuously conveyed through a guide roll or the like. . Stretching can be achieved by gripping with two pairs of nip rolls and increasing the conveyance speed of the subsequent nip roll to be higher than that of the previous nip roll. The draw ratio is based on the length ratio after stretching / initial state (hereinafter the same), but is preferably 1.2 to 3.5 times, particularly 1.5 to 3.0 times in terms of the above-mentioned effects. Then, it is made to dry at 50 to 90 degreeC, and a polarizing layer is obtained.

(B) Diagonal stretching method As the oblique stretching method, a method of stretching using a tenter projecting in an oblique direction in an oblique direction described in JP-A No. 2002-86554 can be used. Since this stretching is performed in the air, it is necessary to make it easy to stretch by adding water in advance. The preferred water content is 5% to 100%, more preferably 10% to 100%.
The temperature during stretching is preferably 40 ° C to 90 ° C, and more preferably 50 ° C to 80 ° C. The humidity is preferably 50% to 100% relative humidity, more preferably 70% to 100% relative humidity, and most preferably 80% to 100% relative humidity. The traveling speed in the longitudinal direction is preferably 1 m / min or more, and more preferably 3 m / min or more.
After the end of stretching, the film is preferably dried at 50 to 100 ° C., more preferably 60 to 90 ° C. for 0.5 to 10 minutes. More preferably, it is 1 minute to 5 minutes.
The absorption axis of the polarizing film thus obtained is preferably 10 ° to 80 °, more preferably 30 ° to 60 °, and still more preferably 45 ° (40 ° to 50 °).

[Lamination]
The saponified cellulose acylate film and a polarizing layer prepared by stretching can be bonded to produce a polarizing plate. The laminating direction is preferably performed so that the casting axis direction of the stretched cellulose acylate film and the stretching axis direction of the polarizing plate are 45 °.
The adhesive used for bonding is not particularly limited, and examples thereof include PVA resins (including modified PVA such as acetoacetyl group, sulfonic acid group, carboxyl group, and oxyalkylene group) and boron compound aqueous solutions. Is preferred. The thickness of the adhesive layer is preferably 0.01 to 10 μm, and particularly preferably 0.05 to 5 μm after drying.
The polarizing plate thus obtained preferably has a higher light transmittance, and preferably has a higher degree of polarization. The transmittance of the polarizing plate is preferably in the range of 30 to 50%, more preferably in the range of 35 to 50%, and most preferably in the range of 40 to 50% in light having a wavelength of 550 nm. . The degree of polarization is preferably in the range of 90 to 100%, more preferably in the range of 95 to 100%, and most preferably in the range of 99 to 100% in light having a wavelength of 550 nm.
Furthermore, the polarizing plate thus obtained can be laminated with a λ / 4 plate to produce circularly polarized light. In this case, lamination is performed so that the slow axis of λ / 4 and the absorption axis of the polarizing plate are 45 °. At this time, λ / 4 is not particularly limited, but more preferably has a wavelength dependency such that the lower the wavelength, the smaller the retardation. Furthermore, it is preferable to use a polarizing film having an absorption axis inclined by 20 ° to 70 ° with respect to the longitudinal direction and a λ / 4 plate made of an optically anisotropic layer made of a liquid crystalline compound.

(2) Application of optical compensation layer (production of optical compensation sheet for liquid crystal display panel)
The optically anisotropic layer is used to compensate for the liquid crystal compound in the liquid crystal cell in the black display of the liquid crystal display device. It is formed by doing.
[Alignment film]
An alignment film can be provided on the surface-treated cellulose acylate film. This film has a function of defining the alignment direction of liquid crystalline molecules. However, if the alignment state is fixed after aligning the liquid crystalline compound, the alignment film plays the role, and thus is not necessarily an essential component of the present invention. That is, it is possible to produce the stretched cellulose acylate film polarizing plate of the present invention by transferring only the optically anisotropic layer on the alignment film in which the alignment state is fixed onto the polarizer.
The alignment film is an organic compound (eg, ω-tricosanoic acid) by rubbing treatment of an organic compound (preferably polymer), oblique deposition of an inorganic compound, formation of a layer having a microgroove, or Langmuir-Blodgett method (LB film). , Dioctadecylmethylammonium chloride, methyl stearylate). Furthermore, an alignment film in which an alignment function is generated by application of an electric field, application of a magnetic field, or light irradiation is also known.
The alignment film is preferably formed by a rubbing treatment of an organic compound (preferably a polymer). In principle, the polymer used for the alignment film has a molecular structure having a function of aligning liquid crystal molecules.
In the present invention, in addition to the function of aligning liquid crystalline molecules, the cross-linking has a function of binding a side chain having a crosslinkable functional group (eg, double bond) to the main chain, or aligning liquid crystal molecules. It is preferable to introduce a functional functional group into the side chain.

As the polymer used for the alignment film, either a polymer that can be crosslinked by itself or a polymer that is crosslinked by a crosslinking agent can be used, and a plurality of combinations thereof can be used. Examples of the polymer include methacrylate copolymer, styrene copolymer, polyolefin, polyvinyl alcohol, modified polyvinyl alcohol, poly (N-methylol) described in paragraph No. [0022] of JP-A-8-338913. Acrylamide), polyester, polyimide, vinyl acetate copolymer, carboxymethylcellulose, polycarbonate and the like. Moreover, a silane coupling agent can be used as a polymer. The polymer is preferably a water-soluble polymer (eg, poly (N-methylolacrylamide), carboxymethylcellulose, gelatin, polyvinyl alcohol, modified polyvinyl alcohol), more preferably gelatin, polyvinyl alcohol, and modified polyvinyl alcohol, and polyvinyl alcohol and modified. Polyvinyl alcohol is most preferred. Further, it is particularly preferable to use two types of polyvinyl alcohol or modified polyvinyl alcohol having different degrees of polymerization. The saponification degree of polyvinyl alcohol is preferably 70 to 100%, and more preferably 80 to 100%. The mass average polymerization degree of polyvinyl alcohol is preferably 100 to 5000.
A side chain having a function of aligning liquid crystal molecules generally has a hydrophobic group as a functional group. The specific type of functional group can be determined according to the type of liquid crystal molecule and the required alignment state.
For example, the modifying group of the modified polyvinyl alcohol can be introduced by copolymerization modification, chain transfer modification or block polymerization modification. Examples of modifying groups include hydrophilic groups (carboxylic acid groups, sulfonic acid groups, phosphonic acid groups, amino groups, ammonium groups, amide groups, thiol groups, etc.), hydrocarbon groups having 10 to 100 carbon atoms, fluorine atoms Examples include substituted hydrocarbon groups, thioether groups, polymerizable groups (unsaturated polymerizable groups, epoxy groups, azirinidyl groups, etc.), alkoxysilyl groups (trialkoxy, dialkoxy, monoalkoxy), and the like. Specific examples of these modified polyvinyl alcohol compounds include, for example, paragraph numbers [0022] to [0145] in JP-A No. 2000-155216 and paragraph number [0018] in JP-A No. 2002-62426. To those described in [0022].
When a side chain having a crosslinkable functional group is bonded to the main chain of the alignment film polymer, or a crosslinkable functional group is introduced into a side chain having a function of aligning liquid crystal molecules, the polymer of the alignment film is optically anisotropic. The polyfunctional monomer contained in the conductive layer can be copolymerized. As a result, not only between the polyfunctional monomer and the polyfunctional monomer, but also between the alignment film polymer and the alignment film polymer and between the polyfunctional monomer and the alignment film polymer is firmly bonded by a covalent bond. Therefore, the strength of the optical compensation sheet can be remarkably improved by introducing the crosslinkable functional group into the alignment film polymer.

The crosslinkable functional group of the alignment film polymer preferably contains a polymerizable group in the same manner as the polyfunctional monomer. Specific examples include those described in paragraphs [0080] to [0100] in JP-A-2000-155216. Apart from the crosslinkable functional group, the alignment film polymer can also be crosslinked using a crosslinking agent.
Examples of the crosslinking agent include aldehydes, N-methylol compounds, dioxane derivatives, compounds that act by activating carboxyl groups, active vinyl compounds, active halogen compounds, isoxazole, and dialdehyde starch. Two or more kinds of crosslinking agents may be used in combination. Specific examples include compounds described in paragraphs [0023] to [0024] in JP-A-2002-62426. As the crosslinking agent, an aldehyde having a high reaction activity, particularly glutaraldehyde is preferable.
0.1-20 mass% is preferable with respect to a polymer, and, as for the addition amount of a crosslinking agent, 0.5-15 mass% is still more preferable. The amount of the unreacted crosslinking agent remaining in the alignment film is preferably 1.0% by mass or less, and more preferably 0.5% by mass or less. By adjusting in this way, even if the alignment film is used for a long time in a liquid crystal display device or left in a high-temperature and high-humidity atmosphere for a long time, sufficient durability without occurrence of reticulation can be obtained.
The alignment film can be basically formed by applying the polymer as an alignment film forming material and a transparent support containing a crosslinking agent, followed by heating and drying (crosslinking) and rubbing treatment. . As described above, the crosslinking reaction can be carried out at any time after being coated on the transparent support. When a water-soluble polymer such as polyvinyl alcohol is used as the alignment film forming material, the coating solution is preferably a mixed solvent of an organic solvent (eg, methanol) having a defoaming action and water. The ratio of water: methanol is preferably 0: 100 to 99: 1, and more preferably 0: 100 to 91: 9. Thereby, generation | occurrence | production of a bubble is suppressed and the defect of the layer surface of an orientation film and also an optically anisotropic layer reduces remarkably.

The alignment film is preferably applied by spin coating, dip coating, curtain coating, extrusion coating, rod coating, or roll coating. The rod coating method is particularly preferable. The film thickness after drying is preferably 0.1 to 10 μm. Heating and drying can be performed at 20 ° C to 110 ° C. In order to form sufficient crosslinking, the heating and drying temperature is preferably 60 ° C to 100 ° C, and particularly preferably 80 ° C to 100 ° C. The drying time can be 1 minute to 36 hours, preferably 1 minute to 30 minutes. The pH is also preferably set to an optimum value for the crosslinking agent to be used. When glutaraldehyde is used, the pH is 4.5 to 5.5, and 5 is particularly preferable.
The alignment film is provided on the stretched cellulose acylate film of the present invention or an undercoat layer applied in the form of a film. The alignment film can be obtained by rubbing the surface after crosslinking the polymer layer as described above.
For the rubbing treatment, a treatment method widely adopted as a liquid crystal alignment treatment process of LCD can be applied. That is, a method of obtaining the orientation by rubbing the surface of the orientation film in a certain direction using paper, gauze, felt, rubber, nylon, polyester fiber or the like can be used. Generally, it is carried out by rubbing several times using a cloth or the like in which fibers having a uniform length and thickness are planted on average.
When industrially implemented, this is achieved by bringing a rotating rubbing roll into contact with the film with the alignment film being transported. However, the roundness, cylindricity, and deflection (eccentricity) of the rubbing roll can Is preferably 30 μm or less. The film wrap angle on the rubbing roll is preferably 0.1 to 90 °. However, as described in JP-A-8-160430, a stable rubbing treatment can be obtained by winding 360 ° or more. As for the conveyance speed of a film, 1-100 m / min is preferable. It is preferable to select an appropriate rubbing angle in the range of 0 ° to 60 °. When used in a liquid crystal display device, the angle is preferably 40 ° to 50 °. 45 ° is particularly preferred.
The thickness of the alignment film thus obtained is preferably in the range of 0.1 to 10 μm.

Next, the liquid crystalline molecules of the optically anisotropic layer are aligned on the alignment film. Thereafter, as necessary, the alignment film polymer and the polyfunctional monomer contained in the optically anisotropic layer are reacted, or the alignment film polymer is crosslinked using a crosslinking agent.
The liquid crystalline molecules used in the optically anisotropic layer include rod-like liquid crystalline molecules and discotic liquid crystalline molecules. The rod-like liquid crystal molecules and the disk-like liquid crystal molecules may be high-molecular liquid crystals or low-molecular liquid crystals, and further include those in which the low-molecular liquid crystals are cross-linked and no longer exhibit liquid crystallinity.

[Rod-like liquid crystalline molecules]
As rod-like liquid crystalline molecules, azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, alkoxy-substituted phenylpyrimidines , Phenyldioxanes, tolanes and alkenylcyclohexylbenzonitriles are preferably used.
The rod-like liquid crystal molecule includes a metal complex. In addition, a liquid crystal polymer containing a rod-like liquid crystalline molecule in a repeating unit can also be used as the rod-like liquid crystalline molecule. In other words, the rod-like liquid crystal molecule may be bonded to a (liquid crystal) polymer.
For rod-like liquid crystalline molecules, see Chapter 4, Chapter 7 and Chapter 11 of the Chemical Chemistry of the Quarterly Chemical Review Vol. 22, Liquid Crystal Chemistry (1994), and the 142nd Committee of the Japan Society for the Promotion of Science. Described in Chapter 3.
The birefringence of the rod-like liquid crystal molecule is preferably in the range of 0.001 to 0.7.
The rod-like liquid crystalline molecule preferably has a polymerizable group in order to fix its alignment state. The polymerizable group is preferably a radically polymerizable unsaturated group or a cationically polymerizable group. Specifically, for example, the polymerizable groups described in paragraphs [0064] to [0086] of JP-A-2002-62427 are described. Group and a polymerizable liquid crystal compound.

[Disc liquid crystalline molecules]
For discotic liquid crystal molecules, C.I. Destrade et al., Mol. Cryst. 71, 111 (1981), benzene derivatives described in C.I. Destrade et al., Mol. Cryst. 122, 141 (1985), Physics lett, A, 78, 82 (1990); Kohne et al., Angew. Chem. 96, page 70 (1984) and the cyclohexane derivatives described in J. Am. M.M. Lehn et al. Chem. Commun. , 1794 (1985), J. Am. Zhang et al., J. Am. Chem. Soc. 116, 2655 (1994), azacrown type and phenylacetylene type macrocycles are included.
As a discotic liquid crystalline molecule, a compound having liquid crystallinity having a structure in which a linear alkyl group, an alkoxy group, and a substituted benzoyloxy group are radially substituted as a side chain of the mother nucleus with respect to the mother nucleus at the center of the molecule Is also included. The discotic liquid crystalline molecule is preferably a compound in which a molecule or an assembly of molecules has rotational symmetry and can impart a certain orientation. In the optically anisotropic layer formed from the discotic liquid crystalline molecules, the compound finally contained in the optically anisotropic layer does not need to be a discotic liquid crystalline molecule. Also included are compounds that have a group that reacts with heat or light, and that eventually polymerize or cross-link by reaction with heat or light to increase the molecular weight and lose liquid crystallinity. Preferred examples of the discotic liquid crystalline molecules are described in JP-A-8-50206. The polymerization of discotic liquid crystalline molecules is described in JP-A-8-27284.
In order to fix the discotic liquid crystalline molecules by polymerization, it is necessary to bond a polymerizable group as a substituent to the discotic core of the discotic liquid crystalline molecules. The discotic core and the polymerizable group are preferably compounds that are bonded via a linking group, whereby the orientation state can be maintained even in the polymerization reaction. Examples thereof include compounds described in paragraphs [0151] to “0168” in JP-A No. 2000-155216.

In the hybrid alignment, the angle between the major axis (disk surface) of the discotic liquid crystalline molecule and the surface of the polarizing film increases or decreases in the depth direction of the optically anisotropic layer and with increasing distance from the surface of the polarizing film. is doing. The angle preferably decreases with increasing distance. Further, the angle change can be continuous increase, continuous decrease, intermittent increase, intermittent decrease, change including continuous increase and continuous decrease, or intermittent change including increase and decrease. . The intermittent change includes a region where the inclination angle does not change in the middle of the thickness direction. Even if the said angle includes the area | region where an angle does not change, it should just increase or decrease as a whole. Furthermore, it is preferred that the angle changes continuously.
The average direction of the major axis of the discotic liquid crystalline molecules on the alignment film side can be generally adjusted by selecting the discotic liquid crystalline molecules or the material of the alignment film, or by selecting the rubbing treatment method. Further, the major axis (disk surface) direction of the disk-like liquid crystalline molecules on the surface side (air side) is generally adjusted by selecting the kind of additive used together with the disk-like liquid crystalline molecules or the disk-like liquid crystalline molecules. be able to. Examples of the additive used together with the discotic liquid crystalline molecule include a plasticizer, a surfactant, a polymerizable monomer and a polymer. The degree of change in the orientation direction of the long axis can be adjusted by selecting liquid crystal molecules and additives, as described above.

[Other compositions of optically anisotropic layer]
Along with the liquid crystal molecules, a plasticizer, a surfactant, a polymerizable monomer, etc. can be used in combination to improve the uniformity of the coating film, the strength of the film, the orientation of the liquid crystal molecules, and the like. These are preferably compatible with the liquid crystalline molecules and can change the tilt angle of the liquid crystalline molecules or do not inhibit the alignment.
Examples of the polymerizable monomer include radically polymerizable or cationically polymerizable compounds. Preferably, it is a polyfunctional radically polymerizable monomer, and more preferable is one that is copolymerizable with the liquid crystal compound containing the polymerizable group. Examples of the polymerizable monomer include those described in paragraph numbers [0018] to [0020] in JP-A-2002-296423. The amount of the compound added is generally in the range of 1 to 50% by mass and preferably in the range of 5 to 30% by mass with respect to the discotic liquid crystalline molecules.
Examples of the surfactant include conventionally known compounds, and fluorine compounds are particularly preferable. Specific examples include compounds described in paragraph numbers [0028] to [0056] in JP-A-2001-330725.
The polymer used together with the discotic liquid crystalline molecule is preferably capable of changing the tilt angle of the discotic liquid crystalline molecule.
Examples of such polymers include cellulose esters. Preferable examples of the cellulose ester include those described in paragraph [0178] of JP-A No. 2000-155216. The addition amount of the polymer is preferably in the range of 0.1 to 10% by mass, and preferably in the range of 0.1 to 8% by mass with respect to the liquid crystal molecule so as not to disturb the alignment of the liquid crystal molecules. It is more preferable.
The discotic nematic liquid crystal phase-solid phase transition temperature of the discotic liquid crystalline molecules is preferably 70 to 300 ° C, more preferably 70 to 170 ° C.

[Formation of optically anisotropic layer]
The optically anisotropic layer can be formed by applying a coating liquid containing liquid crystalline molecules and, if necessary, a polymerization initiator described later and optional components on the alignment film.
As a solvent used for preparing the coating solution, an organic solvent is preferably used. Examples of organic solvents include amides (eg, N, N-dimethylformamide), sulfoxides (eg, dimethyl sulfoxide), heterocyclic compounds (eg, pyridine), hydrocarbons (eg, benzene, hexane), alkyl halides (eg, , Chloroform, dichloromethane, tetrachloroethane), esters (eg, methyl acetate, butyl acetate), ketones (eg, acetone, methyl ethyl ketone), ethers (eg, tetrahydrofuran, 1,2-dimethoxyethane). Alkyl halides and ketones are preferred. Two or more organic solvents may be used in combination.
The coating liquid can be applied by a known method (eg, wire bar coating method, extrusion coating method, direct gravure coating method, reverse gravure coating method, die coating method).
The thickness of the optically anisotropic layer is preferably 0.1 to 20 μm, more preferably 0.5 to 15 μm, and most preferably 1 to 10 μm.

[Fixing the alignment state of liquid crystalline molecules]
The aligned liquid crystalline molecules can be fixed while maintaining the alignment state. The immobilization is preferably performed by a polymerization reaction. The polymerization reaction includes a thermal polymerization reaction using a thermal polymerization initiator and a photopolymerization reaction using a photopolymerization initiator. The polymerization reaction is preferably a photopolymerization reaction.
Examples of the photopolymerization initiator include α-carbonyl compounds (described in US Pat. Nos. 2,367,661 and 2,367,670), acyloin ether (described in US Pat. No. 2,448,828), α-hydrocarbon substituted aromatics. An acyloin compound (described in US Pat. No. 2,722,512), a polynuclear quinone compound (described in US Pat. Nos. 3,046,127 and 2,951,758), a combination of a triarylimidazole dimer and p-aminophenyl ketone (US Pat. No. 3,549,367) Acridine and phenazine compounds (JP-A-60-105667, U.S. Pat. No. 4,239,850) and oxadiazole compounds (U.S. Pat. No. 4,212,970).
The amount of the photopolymerization initiator used is preferably in the range of 0.01 to 20% by mass, more preferably in the range of 0.5 to 5% by mass, based on the solid content of the coating solution.
It is preferable to use ultraviolet rays for light irradiation for polymerization of liquid crystalline molecules.
The irradiation energy is preferably in the range of ^{20mJ / cm 2 ~50J / cm 2} , more preferably in the range of ^{20mJ / cm 2 ~5000mJ / cm 2} , a range of 100mJ / cm ² ~800mJ / cm ² More preferably, In order to accelerate the photopolymerization reaction, light irradiation may be performed under heating conditions.
A protective layer may be provided on the optically anisotropic layer.

It is also preferable to combine this optical compensation film and a polarizing layer. Specifically, the optically anisotropic layer is formed by coating the coating liquid for the optically anisotropic layer as described above on the surface of the polarizing layer. As a result, without using a polymer film between the polarizing layer and the optically anisotropic layer, it is possible to produce a thin polarizing plate having a small stress (strain × cross-sectional area × elastic modulus) associated with the dimensional change of the polarizing layer. When a polarizing plate including the stretched cellulose acylate film of the present invention is attached to a large liquid crystal display device, an image with high display quality can be displayed without causing problems such as light leakage.
The tilt angle between the polarizing layer and the optical compensation layer is stretched so as to match the angle formed by the transmission axis of the two polarizing layers bonded to both sides of the liquid crystal cell constituting the LCD and the vertical or horizontal direction of the liquid crystal cell. It is preferable. A normal inclination angle is 45 °. Recently, however, devices that are not necessarily 45 ° have been developed for transmissive, reflective, and transflective LCDs, and it is preferable that the stretching direction can be arbitrarily adjusted in accordance with the design of the LCD.

[Liquid Crystal Display]
Each liquid crystal mode in which the above optical compensation film is used will be described.
(TN mode liquid crystal display)
The TN mode liquid crystal display device 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.

(OCB mode liquid crystal display)
The OCB mode liquid crystal display device is a bend alignment mode liquid crystal cell in which rod-like liquid crystal molecules are aligned in a substantially opposite direction (symmetrically) between an upper portion and a lower portion of the liquid crystal cell. Liquid crystal display devices using a bend alignment mode liquid crystal cell are disclosed in US Pat. Nos. 4,583,825 and 5,410,422. Since the rod-like liquid crystal molecules are symmetrically aligned at the upper and lower portions of the liquid crystal cell, the bend alignment mode liquid crystal cell has a self-optical compensation function. For this reason, this liquid crystal mode is also called an OCB (Optically Compensatory Bend) liquid crystal mode.
Similarly to the TN mode, the liquid crystal cell in the OCB mode is in a black display, and the alignment state in the liquid crystal cell is such that the rod-like liquid crystal molecules rise in the center of the cell and the rod-like liquid crystal molecules lie in the vicinity of the cell substrate. .

(VA mode liquid crystal display device)
The VA mode liquid crystal display device is characterized in that the rod-like liquid crystalline molecules are aligned substantially vertically when no voltage is applied. (1) No voltage is applied to the VA mode liquid crystal cell. In addition to a narrowly-defined VA mode liquid crystal cell (described in JP-A-2-176625), which is sometimes oriented substantially vertically and oriented substantially horizontally when a voltage is applied, (2) VA mode multi-domain (MVA mode) liquid crystal cell (SID97, Digest of tech. Papers 28 (1997) 845 description), (3) Rod-like liquid crystal molecules are substantially vertical when no voltage is applied A liquid crystal cell in a mode (n-ASM mode) in which it is aligned and twisted and multi-domain aligned when a voltage is applied (described in the proceedings of the Japanese Liquid Crystal Society 58-59 (1998)) and ( ) A SURVIVAL-mode liquid crystal cell (reported in LCD International 98) includes.

(IPS mode liquid crystal display)
The IPS mode liquid crystal display device is characterized in that rod-like liquid crystalline molecules are substantially aligned horizontally in the plane when no voltage is applied, and this is switched by changing the alignment direction of the liquid crystal with and without voltage application. Is a feature. 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.

(Other liquid crystal display devices)
The ECB mode and the STN mode can be optically compensated based on the same concept as described above.

(3) Application of antireflection layer (antireflection film)
In general, the antireflection layer comprises a low refractive index layer which is also an antifouling layer, and at least one layer having a higher refractive index than that of the low refractive index layer (ie, a high refractive index layer and a medium refractive index layer). It is provided on a stretched cellulose acylate film.
Colloidal metal by multilayer deposition of transparent thin films of inorganic compounds (metal oxides, etc.) with different refractive indexes by chemical vapor deposition (CVD) method, physical vapor deposition (PVD) method, sol-gel method of metal compounds such as metal alkoxides Examples include a method of forming a thin film by post-processing (ultraviolet irradiation: JP-A-9-157855, plasma processing: JP-A-2002-327310) after forming an oxide particle film.
On the other hand, various antireflection layers formed by laminating and applying a thin film in which inorganic particles are dispersed in a matrix have been proposed as an antireflection layer with high productivity.
Further, examples of the antireflection layer include an antireflection film comprising an antireflection layer provided with an antiglare property in which the surface of the uppermost layer has a fine uneven shape on the antireflection film formed by coating as described above. It is done.
The stretched cellulose acylate film of the present invention can be applied to any of the above methods, but the coating method (coating type) is particularly preferred.

[Layer structure of coating type antireflection film]
An antireflection layer comprising at least a middle refractive index layer, a high refractive index layer, and a low refractive index layer (outermost layer) in order on the substrate which is the stretched cellulose acylate film of the present invention satisfies the following relational expression. It is designed to have a refractive index.
Relational expression: refractive index of high refractive index layer> refractive index of medium refractive index layer> refractive index of transparent support> refractive index of low refractive index layer Also, transparent support (stretched cellulose acylate film of the present invention) and medium A hard coat layer may be provided between the refractive index layer. Further, the antireflection layer may comprise a medium refractive index hard coat layer, a high refractive index layer and a low refractive index layer.
Examples of the antireflection film include JP-A-8-122504, JP-A-8-110401, JP-A-10-300902, JP-A-2002-243906, JP-A-2000-11706, and the like. . In addition, other functions may be imparted to each of the above-described layers. For example, a layer having an antifouling low refractive index layer and an antistatic high refractive index layer (for example, JP-A-10-206603, No. 2002-243906) and the like.
The haze of the antireflection layer is preferably 5% or less, more preferably 3% or less. Further, the strength of the film is preferably H or more, more preferably 2H or more, and most preferably 3H or more in a pencil hardness test according to JIS K5400.

[High refractive index layer and medium refractive index layer]
The layer having a high refractive index (high refractive index layer) of the antireflection film is composed of a curable film containing at least an inorganic compound ultrafine particle having a high refractive index having an average particle size of 100 nm or less and a matrix binder.
The inorganic compound ultrafine particles having a high refractive index include inorganic compounds having a refractive index of 1.65 or more, preferably those having a refractive index of 1.9 or more. Examples of high refractive index inorganic compound ultrafine particles include oxides such as Ti, Zn, Sb, Sn, Zr, Ce, Ta, La, and In, and composite oxides containing these metal atoms.
In order to obtain such ultrafine particles, a method of treating the particle surface with a surface treatment agent (for example, silane coupling agent, etc .: JP-A-11-295503, JP-A-11-153703, JP-A-2000-9908). Gazette, anionic compound or organometallic coupling agent (JP 2001-310432 A, etc.), a method of forming a core-shell structure with high refractive index particles as a core (JP 2001-166104 A, etc.), combined use with a specific dispersant (Japanese Patent Application Laid-Open No. 11-153703, US Pat. No. 6,210,858, Japanese Patent Application Laid-Open No. 2002-27776069, etc.) can be used.
Examples of the material forming the matrix include conventionally known thermoplastic resins and curable resin films.
Furthermore, the material forming the matrix includes a polyfunctional compound-containing composition having at least two radically polymerizable and / or cationically polymerizable groups, an organometallic compound containing a hydrolyzable group, and a portion thereof. At least one composition selected from condensate compositions is preferred. Examples thereof include compounds described in JP-A Nos. 2000-47004, 2001-315242, 2001-31871, and 2001-296401.
A curable film obtained from a colloidal metal oxide obtained from a hydrolyzed condensate of metal alkoxide and a metal alkoxide composition is also preferred. Such a curable film is described in, for example, JP-A-2001-293818.
The refractive index of the high refractive index layer is generally 1.70 to 2.20. The thickness of the high refractive index layer is preferably 5 nm to 10 μm, and more preferably 10 nm to 1 μm.
The refractive index of the middle refractive index layer is preferably adjusted to be a value between the refractive index of the low refractive index layer and the refractive index of the high refractive index layer. The refractive index of the middle refractive index layer is preferably 1.50 to 1.70.

[Low refractive index layer]
The low refractive index layer is formed by sequentially laminating on the high refractive index layer. The refractive index of the low refractive index layer is preferably 1.20 to 1.55, more preferably 1.30 to 1.50.
The low refractive index layer is preferably constructed as an outermost layer having scratch resistance and antifouling properties. As a means for greatly improving the scratch resistance, it is effective to impart slipperiness to the surface, and it is possible to apply a thin film layer means including introduction of silicone by a conventionally known silicone compound, introduction of fluorine by a fluorine-containing compound, or the like.
The refractive index of the fluorine-containing compound is preferably 1.35 to 1.50, more preferably 1.36 to 1.47. The fluorine-containing compound is preferably a compound containing a crosslinkable or polymerizable functional group containing fluorine atoms in the range of 35 to 80% by mass.
Examples of the fluorine compound include paragraphs [0018] to [0026] of JP-A-9-222503, paragraphs [0019] to [0030] of JP-A-11-38202, and JP-A-2001-40284. And the compounds described in paragraph numbers [0027] to [0028] of JP-A No. 2000-284102.

The silicone compound is a compound having a polysiloxane structure, preferably containing a curable functional group or a polymerizable functional group in the polymer chain and having a crosslinked structure in the film. For example, reactive silicone (eg, Silaplane (manufactured by Chisso Corporation), silanol group-containing polysiloxane (Japanese Patent Laid-Open No. 11-258403, etc.) and the like can be mentioned.
The crosslinking or polymerization reaction of the fluorine-containing and / or siloxane polymer having a crosslinkable group or a polymerizable group is performed simultaneously with the application of the coating composition for forming the outermost layer containing a polymerization initiator, a sensitizer, or the like. It is preferable to carry out by light irradiation or heating after coating.
Further, as the low refractive index layer, a sol-gel cured film in which an organometallic compound such as a silane coupling agent and a specific fluorine-containing hydrocarbon group-containing silane coupling agent are cured by a condensation reaction in the presence of a catalyst is also preferable.
Examples of these silane coupling agents include polyfluoroalkyl group-containing silane compounds or partially hydrolyzed condensates thereof (Japanese Patent Laid-Open Nos. 58-142958, 58-147483, 58-147484, and Japanese Patent Laid-Open No. 58-147484). 9-157582, 11-106704, etc.), silyl compounds containing a (poly) perfluoroalkyl ether group which is a fluorine-containing long chain group (Japanese Patent Application Laid-Open No. 2000-117902, 2001) -48590 gazette and 2002-53804 gazette etc.) etc. are mentioned.
The low refractive index layer has an average primary particle diameter of 1 to 150 nm such as a filler (for example, silicon dioxide (silica), fluorine-containing particles (magnesium fluoride, calcium fluoride, barium fluoride)) as an additive other than the above. Low refractive index inorganic compounds, organic fine particles described in paragraphs [0020] to [0038] of JP-A-11-3820, etc.), silane coupling agents, slip agents, surfactants, and the like can be contained.

When the low refractive index layer is located below the outermost layer, the low refractive index layer may be formed by a vapor phase method (vacuum deposition method, sputtering method, ion plating method, plasma CVD method, etc.). The coating method is preferable because it can be manufactured at a low cost.
The film thickness of the low refractive index layer is preferably 30 to 200 nm, more preferably 50 to 150 nm, and most preferably 60 to 120 nm.

[Hard coat layer]
The hard coat layer can be provided on the surface of the substrate which is the stretched cellulose acylate film of the present invention in order to impart physical strength to the antireflection film. In particular, the hard coat layer is preferably provided between the base material and the high refractive index layer.
The hard coat layer is preferably formed by a crosslinking reaction or a polymerization reaction of a light and / or heat curable compound. The curable functional group of the curable compound is preferably a photopolymerizable functional group, and the hydrolyzable functional group-containing organometallic compound is preferably an organic alkoxysilyl compound.
Specific examples of these compounds are the same as those exemplified for the high refractive index layer.
Specific examples of the constituent composition of the hard coat layer include those described in JP-A Nos. 2002-144913, 2000-9908, and International Publication WO0 / 46617.
The high refractive index layer described above can also serve as a hard coat layer. In such a case, it is preferable to form fine particles dispersed in the hard coat layer using the method described for the high refractive index layer.
A hard-coat layer can also serve as the glare-proof layer (after-mentioned) which contained the particle | grains with an average particle diameter of 0.2-10 micrometers and provided the glare-proof function (anti-glare function).
The film thickness of the hard coat layer can be appropriately designed depending on the application. The film thickness of the hard coat layer is preferably 0.2 to 10 μm, more preferably 0.5 to 7 μm.
The strength of the hard coat layer is preferably H or more, more preferably 2H or more, and most preferably 3H or more in a pencil hardness test according to JIS K5400. Further, in the Taber test according to JIS K5400, the smaller the wear amount of the test piece before and after the test, the better.

[Forward scattering layer]
When applied to a liquid crystal display device, the forward scattering layer can be provided in order to provide an effect of improving the viewing angle when the viewing angle is inclined in the vertical and horizontal directions. Further, by dispersing fine particles having different refractive indexes in the hard coat layer, it can also serve as a hard coat function.
Examples of the forward scattering layer include, for example, Japanese Patent Application Laid-Open No. 11-38208 in which the forward scattering coefficient is specified, Japanese Patent Application Laid-Open No. 2000-199809 in which the relative refractive index of the transparent resin and the fine particles is in a specific range, and a haze value of 40%. The thing as described in Unexamined-Japanese-Patent No. 2002-107512 etc. which were prescribed | regulated as mentioned above is mentioned.

[Other layers]
In addition to the above layers, a primer layer, an antistatic layer, an undercoat layer, a protective layer, and the like may be provided on the saturated norbornene film of the present invention.
[Coating method]
Each layer of the antireflection film is formed by dip coating, air knife coating, curtain coating, roller coating, wire bar coating, gravure coating, micro gravure method or extrusion coating method (US Pat. No. 2,681,294). According to the specification, it can be formed by coating.
[Anti-glare function]
The antireflection film may have an antiglare function that scatters external light. The antiglare function is obtained by forming irregularities on the surface of the antireflection film. When the antireflection film has an antiglare function, the haze of the antireflection film is preferably 3 to 30%, more preferably 5 to 20%, and most preferably 7 to 20%.
As a method for forming irregularities on the surface of the antireflection film, any method can be applied as long as these surface shapes can be sufficiently retained. For example, a method of forming irregularities on the film surface using fine particles in the low refractive index layer (for example, JP 2000-271878 A), a lower layer of the low refractive index layer (high refractive index layer, medium refractive index layer) Alternatively, a small amount (0.1 to 50% by mass) of relatively large particles (particle size 0.05 to 2 μm) is added to the hard coat layer to form a surface uneven film, and these shapes are maintained thereon. A method of providing a low refractive index layer (for example, JP-A-2000-281410, 2000-95893, 2001-100004, 2001-281407, etc.), uppermost layer (antifouling layer) A method of physically transferring the uneven shape onto the surface after coating (for example, as an embossing method, JP-A 63-278839, JP-A 11-183710, JP-A 2000-275401, etc. Etc. The.

[Measuring method]
The measurement method used in the present invention is described below.
(1) Orientation angle distribution and orientation angle distribution variation with temperature and humidity First, 9 points are sampled at equal intervals in the width direction, and 3 points are sampled every 10 m in the longitudinal direction, and 27 films each having a size of 1 cm □ are sampled. Take out.
After the above-mentioned film is conditioned for 3 hours or more under the conditions of 25 ° C. and 60% relative humidity, an automatic birefringence meter (automatic birefringence meter KOBRA-21ADH: manufactured by Oji Scientific Instruments) is used. The direction of the slow axis in the plane (the angle with respect to the width direction during casting film formation) is measured (Fresh).
Next, after preparing the above-described measurement film for 1000 hours at 60 ° C. and 90% relative humidity, the humidity is adjusted for 3 hours or more at 25 ° C. and 60% relative humidity, and the same measurement is performed.

(2) Re, Rth and Re, Rth fluctuations with humidity First, 9 points are equally spaced in the width direction and 3 points are sampled every 10 m in the longitudinal direction, and 27 films having a size of 1 cm □ are taken out.
Next, the sample film was conditioned at 25 ° C. and 60% relative humidity for 3 hours or more, and then using an automatic birefringence meter (KOBRA-21ADH / PR: manufactured by Oji Scientific Instruments), 25 ° C. and relative humidity 60 %, The retardation value at a wavelength of 550 nm is measured from the direction perpendicular to the sample film surface and tilted by ± 40 ° from the normal to the film surface. The in-plane retardation (Re) is calculated from the vertical direction, and the retardation (Rth) in the thickness direction is calculated from the measured value in the vertical direction and the measured value in the ± 40 ° direction from the normal to the film surface. Let these be Re (60) and Rth (60). Re and Rth when not specified indicate this value.
Furthermore, using these samples as they are, measurement is performed at 25 ° C. and a relative humidity of 10% to obtain Re (10) and Rth (10). Further, these samples were measured at 25 ° C. and a relative humidity of 80% to obtain Re (80) and Rth (80).
For each sample, the humidity Re fluctuation and the humidity Rth fluctuation are obtained according to the following formula, and the average of 27 measurement points is obtained.
Humidity Re fluctuation (% /.% Relative humidity) = [100 × {absolute value of difference between Re (80) and Re (10)} / Re (60)] / 70
Humidity Rth variation (% /. Relative humidity%) = [100 × {absolute value of difference between Rth (80) and Rth (10)} / Rth (60)] / 70
The change in humidity of Re and Rth is the difference between Re and Rth at 10% relative humidity and Re and Rth at 80% relative humidity divided by Re and Rth measured at 60% relative humidity, respectively. is there

(3) Residual amount of solvent After measuring the mass M of the cellulose acylate film at the time of stretching, the film is dried at 120 ° C. for 3 hours, and the mass N is measured. The solvent residual amount is calculated from the following formula (1).
Residual amount of solvent = (M−N) × 100 / N (1)
(M is the mass of the cellulose acylate film at the time of stretching, and N means the mass after drying the cellulose acylate film at 120 ° C. for 3 hours.)

(4) Glass transition temperature First, 10 mg of the solution-formed film is sampled and placed in a DSC measurement pan. Next, this is heated from 30 ° C. to 250 ° C. at 10 ° C./min in a nitrogen stream (1st-run), and then cooled to 30 ° C. at −10 ° C./min. Thereafter, the temperature is raised again from 30 ° C. to 250 ° C. (2nd-run), and the glass transition temperature (Tg) is determined at the 2nd-run. The Tg refers to the temperature at which the baseline begins to deviate from the low temperature side.

(5) Degree of substitution of cellulose acylate The degree of acyl substitution of cellulose acylate is determined according to Carbohydr. Res. 273 (1995) 83-91 (Tezuka et al.).

The specific embodiment about the manufacturing method of this invention and a stretched cellulose acylate film is described below. 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 should not be construed as being limited by the specific examples shown below.
[Example 1]
1. Formation of Cellulose Acylate Film (1) Preparation of Cellulose Acylate Cellulose acylate having an acetyl group substitution degree of 2.0, a propionyl group substitution degree of 0.8, and a viscosity average polymerization degree of 350 Was made. The cellulose acylate is a mixture of carboxylic acid (acetic acid and propionic acid), carboxylic acid anhydride (acetic anhydride and propionic acid anhydride), and sulfuric acid as a catalyst (7.8 parts by mass with respect to 100 parts by mass of cellulose). After cooling to −20 ° C., it was added to cellulose, and the maximum temperature was adjusted to 30 ° C. for acylation. At this time, the charged molar ratio of acetyl and propionyl was acetyl: propionyl = 0.46: 0.54. After the acylation was completed, water was added to the reaction mixture to hydrolyze the acid anhydride, and the mixture was aged at 60 ° C. for 1.5 hours to adjust the total substitution degree. The content of acetyl and propionyl in the obtained cellulose acylate was determined by the area intensity ratio of ¹ H-NMR. The degree of polymerization of cellulose acylate was determined by the following method.

(Degree of polymerization measurement method)
About 0.2 g of completely dried cellulose acylate was precisely weighed and dissolved in 100 ml of a mixed solvent of methylene chloride: ethanol = 9: 1 (mass ratio). This was measured with an Ostwald viscometer for the number of seconds dropped at 25 ° C., and the degree of polymerization was determined by the following formulas (1) to (3).
ηrel = T / T ₀ (1)
[Η] = (lnηrel) / C (2)
DP = [η] / Km (3)
T: The number of seconds for dropping the measurement sample T ₀ : The number of seconds for dropping the solvent alone ln: Natural logarithm C: Concentration (g / l)
Km: 6 × 10 ^-4

(2) Dissolution of cellulose acylate (i) Preparation of solvent A solvent composition having a solvent composition consisting of dichloromethane (83.0 mass%) and ethanol (17.0 mass%) was prepared.
(Ii) Drying of cellulose acylate The above-mentioned cellulose acylate was dried to adjust the water content to 0.5% or less.
(Iii) Addition of additive The additive having the following composition was added to the solvent obtained above. In addition, all the following addition amount (mass%) is a ratio with respect to the absolute dry mass of a cellulose acylate.
[Additive composition]
Plasticizer A: Triphenyl phosphate (3% by mass)
Plasticizer B: biphenyl diphenyl phosphate (1% by mass)
Optical anisotropy control agent: plate-like compound described in (Chemical Formula 1) described in JP-A-2003-66230 (3% by mass)
UV agent a: 2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-tert-butylanilino) -1,3,5-triazine (0.5% by mass)
UV agent b: 2 (2′-hydroxy-3 ′, 5′-di-tert-butylphenyl) -5-chlorobenzotriazole (0.2% by mass)
UV agent c: 2 (2′-hydroxy-3 ′, 5′-di-tert-amylphenyl) -5-chlorobenzotriazole (0.1% by mass)
Fine particles: silicon dioxide (particle size 20 nm, Mohs hardness: about 7) (0.25% by mass)
Citric acid ethyl ester (monoester: diester (= 1: 1 mixed)) (0.2% by mass)

(Iv) Swelling / Dissolution The cellulose acylate was added to the solvent containing the additive obtained above with stirring. After the stirring was stopped, a slurry was prepared by swelling at 25 ° C. for 3 hours. The slurry was stirred again to completely dissolve the cellulose acylate.

(V) Filtration After dissolution, the slurry is filtered with a filter paper having an absolute filtration accuracy of 0.01 mm (manufactured by Toyo Filter Paper Co., Ltd., # 63), and further filtered to a filter paper having an absolute filtration accuracy of 2.5 μm (FH025, manufactured by Pole). And filtered to obtain a cellulose acylate solution. The concentration of the cellulose acylate solution was 25% by mass (total solid content × 100 / (total solid content + solvent amount)).

(3) Film formation The above-mentioned cellulose acylate solution was heated to 30 ° C. and cast by the following band method. In the band method, the cellulose acylate solution was passed through a Giesser and cast on a mirror surface stainless steel support having a band length of 60 m set at 15 ° C. The Gieser used was similar to that described in JP-A-11-314233. The space temperature of the casting part was 40 ° C.

(4) Peeling / stretching The cellulose acylate film was peeled from the mirror surface stainless steel support when the residual solvent reached 90% by mass. Next, stretching was performed in the width direction in the tenter. The space temperature of the stretched part at the start of stretching was 110 ° C., the temperature of the film was 58 ° C., and the residual solvent amount was 25% by mass. In the middle of stretching, the space temperature of the stretched portion was 110 ° C., the temperature of the film was 100 ° C., and stretching was performed so that the stretch ratio was 80% when the residual solvent amount was 15% by mass. Thereafter, the film was stretched at a maximum stretching ratio of 30% when the residual solvent amount was 12% by mass. At this time, the space temperature of the stretched portion was 130 ° C., and the temperature of the film was 128 ° C. After trimming both ends of the stretched cellulose acylate film thus obtained by 3 cm, a knurling having a height of 100 μm was applied to a portion of 2 to 10 mm from both ends, and wound into a 3000 m roll.

[Example 2]
In “1. (1) Production of Cellulose Acylate” in Example 1, the substitution ratio of acetyl group is 0 by changing the molar ratio of the preparation of acylation to acetyl: propionyl = 0.05: 0.95. A cellulose acylate having a substitution degree of .2 and a propionyl group of 2.5 and a viscosity average polymerization degree of 350 was prepared. In the above “1. (2) (i) Preparation of solvent”, the solvent composition is dichloromethane (81.6% by mass), methanol (14.8% by mass), and n-butanol (3.6% by mass). In the stretching step in “1. (4) Peeling / stretching”, the space temperature of the stretched portion at the start of stretching is 100 ° C., the temperature of the film is 41 ° C., and the residual solvent amount is 30% by mass. Met. In the middle of stretching, stretching was performed so that the stretching ratio was 85% when the space temperature of the stretching portion was 100 ° C, the temperature of the film was 92 ° C, and the residual solvent amount was 15% by mass. Thereafter, stretching was performed at a maximum stretching ratio of 120% when the residual solvent amount was 3% by mass. At this time, the space temperature of the stretched portion was 135 ° C., and the temperature of the film was 130 ° C. Thereafter, Examples except that the cellulose acylate film was relaxed so that the ratio of the width after relaxation to the width at maximum stretching (= width after relaxation × 100 / width at maximum stretching before relaxation) was 90%. In the same manner as in Example 1, a stretched cellulose acylate film of Example 2 was produced.

[Example 3]
In Example 1, “1. (1) Production of Cellulose Acylate”, the molar ratio of the acylation charge was changed to acetyl: butyryl = 0.45: 0.55, whereby the degree of acetyl substitution was 2.0. And a cellulose acylate having a butyryl substitution degree of 0.7 and a viscosity average degree of polymerization of 300. In the above-mentioned "1. (2) (i) Preparation of solvent", the solvent composition is dichloromethane ( 81.6% by mass), methanol (14.8% by mass), and n-butanol (3.6% by mass) are prepared, and in the casting step in “1. The space temperature of the extension was 20 ° C. In the stretching step in “1. (4) Peeling / stretching”, the space temperature of the stretched portion at the start of stretching was 60 ° C., the temperature of the film was 22 ° C., and the residual solvent amount was 53 mass%. In the course of stretching, stretching was performed so that the stretching ratio was 40% when the space temperature of the stretching portion was 60 ° C., the temperature of the film was 57 ° C., and the residual solvent amount was 15% by mass. Thereafter, stretching was performed at a maximum stretching ratio of 50% when the residual amount of the solvent was 2% by mass. At this time, the space temperature of the stretched part was 125 ° C., and the temperature of the film was 121 ° C. Thereafter, Examples except that the cellulose acylate film was relaxed so that the ratio of the width after relaxation to the width at maximum stretching (= width after relaxation × 100 / width at maximum stretching before relaxation) was 90%. In the same manner as in Example 1, a stretched cellulose acylate film of Example 3 was produced.

[Example 4]
In Example 1, “1. (1) Production of Cellulose Acylate”, the molar ratio of the preparation of acylation was changed to acetyl: butyryl = 0.20: 0.80, whereby the degree of acetyl substitution was 1.0. And a cellulose acylate having a butyryl substitution degree of 1.7 and a viscosity average polymerization degree of 300 was prepared. In the above-mentioned “1. (2) (i) Preparation of solvent”, the solvent composition was dichloromethane (81 0.6 mass%), methanol (14.8 mass%), and n-butanol (3.6 mass%). In the stretching step in “1. (4) Peeling / stretching”, the space temperature of the stretched portion at the start of stretching was 100 ° C., the temperature of the film was 70 ° C., and the residual solvent amount was 20 mass%. In the middle of stretching, stretching was performed such that the space temperature of the stretched portion was 100 ° C., the temperature of the film was 91 ° C., and the stretch ratio was 80% when the solvent residual amount was 15% by mass. Thereafter, the film was stretched at a maximum stretching ratio of 240% when the residual solvent amount was 5% by mass. At this time, the space temperature of the stretched part was 120 ° C, and the temperature of the film was 112 ° C. Thereafter, the same as in Example 1 except that the ratio of the width after relaxation to the width at maximum stretching (= width after relaxation × 100 / width at maximum stretching before relaxation) was 95%. The stretched cellulose acylate film of Example 4 was produced.

[Example 5]
A stretched cellulose acylate film of Example 5 was produced in the same manner as Example 1 except that the following method was used.
In “1. (1) Production of cellulose acylate” in Example 1, the degree of acetyl substitution of cellulose is 2.7, the degree of substitution of acyl groups having 3 to 22 carbon atoms is 0, and viscosity average polymerization is performed. A cellulose acylate having a degree of 300 was produced. In the above "1. (2) (i) Preparation of solvent", the solvent composition is methyl acetate (81.0% by mass), acetone (8.0 parts by mass), ethanol (7.0% by mass), n- A solvent of butanol (4.0% by mass) was prepared.

  In the above "1. (2) (iii) Addition of additive", the content of plasticizer A: triphenyl phosphate is 9 mass% in the composition of the additive, and plasticizer B: biphenyl diphenyl phosphate. The content was changed to 3% by mass, the optical anisotropy control agent: the content of the plate-like compound described in (Chemical Formula 1) described in JP-A-2003-66230 was changed to 6% by mass. The concentration of the cellulose acylate solution was adjusted to 17% by mass (total solid content × 100 / (total solid content + solvent amount)).

In “1. (2) (iv) Swelling / dissolution”, the cellulose acylate solution after being charged and stirred is fed by a screw pump with the shaft center heated to 40 ° C., and from the outer periphery of the screw. The cooling process which passes a cooling part was performed so that it might cool and it might be 3 minutes at -75 degreeC. In addition, cooling was implemented using the -80 degreeC refrigerant | coolant cooled with the refrigerator.
Further, in the above “1. (3) film formation”, before casting, the cellulose acylate solution is heated to 120 ° C. in the state of 1 MPa at the heating part pressure part in the middle of liquid feeding, and the normal pressure (0 The organic solvent was volatilized by discharging to 0.1 MPa. Then, it cooled and the temperature of the cellulose acylate solution was 40 degreeC. The concentration of the cellulose acylate solution thus prepared was 23% by mass.
Moreover, in the casting process in the “1. (3) film formation”, the temperature of the cellulose acylate solution was cast at 40 ° C.
In the above-mentioned "1. (4) peeling step in peeling / stretching, peeling was performed when the residual amount of solvent was 150% by mass. Similarly, in the stretching step, the space temperature of the stretched portion at the start of stretching was 100 ° C, and the temperature of the film. Was 45 ° C. and the residual amount of solvent was 40% by mass .. During stretching, stretching was performed when the space temperature of the stretched part was 100 ° C., the temperature of the film was 74 ° C., and the residual amount of solvent was 15% by mass. The film was stretched so that the ratio was 20%, and the film was stretched at a maximum stretching ratio of 27% when the residual amount of the solvent was 2% by weight, where the space temperature of the stretched portion was 130 ° C. and the temperature of the film was 130 ° C. Thereafter, relaxation was performed such that the ratio of the width after relaxation to the width during maximum stretching (= width after relaxation × 100 / width during maximum stretching before relaxation) was 93%.

[Example 6]
In the stretching process of “1. (4) Peeling / stretching” in Example 5, the space temperature of the stretched part at the start of stretching was 100 ° C., and the temperature of the film was 20 ° C. At this time, the residual solvent amount was 90% by mass. In the course of stretching, stretching was performed so that the stretching ratio was 60% when the space temperature of the stretched portion was 100 ° C, the temperature of the film was 57 ° C, and the residual solvent amount was 15% by mass. Thereafter, the film was stretched at a maximum stretching ratio of 25% when the residual amount of the solvent was 6% by mass. At this time, the space temperature of the stretched portion was 130 ° C., and the temperature of the film was 128 ° C. Thereafter, the same as in Example 5 except that the ratio of the width after relaxation to the width at maximum stretching (= width after relaxation × 100 / width at maximum stretching before relaxation) was 80%. The cellulose acylate film of Example 6 was produced.

[Example 7]
In the above "1. (2) (i) Preparation of solvent" in Example 5, the solvent composition was methyl acetate (82.0 mass%), acetone (10.0 mass%), ethanol (4.0 mass%). , A solvent of n-butanol (4.0% by mass) was prepared. In the casting process in the “1. (3) film formation”, the space temperature of the casting part is changed to 15 ° C., and in the peeling process in the “1. Peeling occurred at 230% by mass. In the stretching step, the space temperature of the stretched portion at the start of stretching was 60 ° C., the film temperature was 17 ° C., and the residual solvent amount was 210% by mass. In the middle of stretching, stretching was performed such that the space temperature of the stretched portion was 60 ° C., the temperature of the film was 59 ° C., and the remaining ratio of the solvent was 15% by mass, so that the stretch ratio was 80%. Thereafter, the film was stretched at a maximum stretching ratio of 25% when the residual solvent amount was 13% by mass. At this time, the space temperature of the stretched part was 125 ° C., and the temperature of the film was 120 ° C. Thereafter, the same as in Example 5 except that the ratio of the width after relaxation to the width at maximum stretching (= width after relaxation × 100 / width at maximum stretching before relaxation) was 70%. The cellulose acylate film of Example 7 was produced.

After adjusting the orientation angle distribution of the cellulose acylate films of Examples 1 to 7 prepared in this manner at 25 ° C. and a relative humidity of 60% for 3 hours or more (Fresh), an automatic birefringence meter (KOBRA-21ADH) : Measured by Oji Scientific Instruments). The orientation angle distribution was within ± 2 °. Next, the above-described measurement film was conditioned for 1000 hours at 60 ° C. and 90% relative humidity, and then conditioned for 3 hours and more at 25 ° C. and 60% relative humidity, and the same measurement was performed. The orientation angle distribution was within ± 2 °.
In addition, as a result of measuring Re, Rth, humidity dependency, and photoelasticity of the cellulose acylate films of Examples 1 to 7 produced by this method, the cellulose acylate films of all the examples have the following ranges. Satisfactory good properties were shown.
0 ≦ Re (nm) ≦ 200
−100 ≦ Rth (nm) ≦ 500
0 ≦ ΔRe (% /% rh) ≦ 90
0 ≦ ΔRth (% /% rh) ≦ 90
Furthermore, according to Example 1 of the Japan Society for Invention and Innovation Technical Report (Public Technical Number 2001-1745), three-layer co-casting was performed using the cellulose acylate film solution, and good results were obtained as described above.

[Comparative Example 1]
In the stretching process of “1. (4) Peeling / stretching” in Example 1, stretching was performed with reference to the stretching conditions described in Example 8 of JP-A-2003-170492. At this time, the space temperature of the stretched part at the start of stretching was 100 ° C., the temperature of the film was 60 ° C., and the residual solvent amount was 20% by mass. Thereafter, a cellulose acylate film of Comparative Example 1 was produced in the same manner as in Example 1 except that when the residual solvent amount was 18% by mass, the film was stretched at a maximum stretching ratio of 40%. In addition, when extending | stretching by the maximum extending | stretching rate, the space temperature of the extending | stretching part was 110 degreeC, and the temperature of the film was 100 degreeC.
After adjusting the orientation angle distribution of the cellulose acylate film of Comparative Example 1 at 25 ° C. and 60% relative humidity for 3 hours or more, using an automatic birefringence meter (KOBRA-21ADH: manufactured by Oji Scientific Instruments) It was measured. The orientation angle distribution was within ± 0.5 °. However, the orientation angle distribution of a cellulose acylate film prepared by preparing the above-described measurement film at a temperature of 60 ° C. and a relative humidity of 90% for 1000 hours and adjusting the humidity at a temperature of 25 ° C. and a relative humidity of 60% for 3 hours or more is ± 4 °. Was within.

[Comparative Example 2]
In Example 1, “1. (1) Production of Cellulose Acylate”, the degree of acetyl substitution of cellulose is 1 by changing the molar ratio of the preparation of acylation to acetyl: butyryl = 0.20: 0.80. A cellulose acylate having a degree of substitution of 0.0 and a butyryl of 1.7 and a viscosity average degree of polymerization of 300 was prepared, and the solvent composition was dichloromethane in the above-mentioned “1. (2) (i) Preparation of solvent”. A solvent composed of (81.6% by mass), methanol (14.8% by mass), and n-butanol (3.6% by mass) was prepared. In the stretching step in “1. (4) Peeling / stretching”, the space temperature of the stretched portion at the start of stretching was 120 ° C., the temperature of the film was 95 ° C., and the residual solvent amount was 20 mass%. In the course of stretching, stretching was performed so that the stretching ratio was 0.8% when the space temperature of the stretched portion was 120 ° C., the temperature of the film was 101 ° C., and the residual solvent amount was 15% by mass. Thereafter, the process was carried out in the same manner as in Example 1 except that the stretching was performed at a space temperature of 130 ° C., but the film was broken during stretching to the maximum stretching ratio.

[Comparative Example 3]
In “1. (1) Production of cellulose acylate” in Example 1, the acetyl substitution degree of cellulose is 1 by changing the molar ratio of the acylation charge to acetyl: butyryl = 0.20: 0.80. A cellulose acylate having a butyryl substitution degree of 1.7 and a viscosity average polymerization degree of 300 was prepared, and the solvent composition was changed to dichloromethane in “1. (2) (i) Preparation of solvent”. (81.6% by mass), methanol (14.8% by mass), a solvent comprising n-butanol (3.6% by mass) is prepared, and in the casting step in the above “1. The space temperature of the casting part was 20 ° C. In the stretching step in “1. (4) Peeling / stretching”, the space temperature of the stretched portion at the start of stretching was 60 ° C., the temperature of the film was 22 ° C., and the residual solvent amount was 42 mass%. When the residual solvent amount was 30% by mass, the film was stretched at a maximum stretching ratio of 50%. At this time, the space temperature of the stretched portion was 140 ° C., and the temperature of the film was 130 ° C. Then, the same as in Example 1 except that the ratio of the width after relaxation to the width at maximum stretching (= width after relaxation × 100 / width at maximum stretching before relaxation) was 90%. A cellulose acylate film of Comparative Example 3 was produced.
After adjusting the orientation angle distribution of the cellulose acylate film prepared in Comparative Example 3 for 3 hours or more at 25 ° C. and 60% relative humidity, an automatic birefringence meter (KOBRA-21ADH: manufactured by Oji Scientific Instruments) was used. And measured. The orientation angle distribution was within ± 4 °. The orientation angle distribution of a cellulose acylate film prepared by preparing such a film for 1000 hours at 60 ° C. and 90% relative humidity and then adjusting the humidity for 3 hours at 25 ° C. and 60% relative humidity was within ± 8 °. .

2. Application of Cellulose Acylate Film 2-1) Production of Polarizing Plate (1) Saponification of Cellulose Acylate Film The stretched cellulose acylate films of Examples 1 to 7 and Comparative Examples 1 and 3 were saponified by the following method. went. In the saponification, a 1.5 N aqueous solution of NaOH was used as a saponification solution, and the temperature was adjusted to 60 ° C., and then the stretched cellulose acylate film was immersed for 2 minutes. Thereafter, the stretched cellulose acylate film was immersed in a 0.1N aqueous sulfuric acid solution for 30 seconds, and then passed through a washing bath.

(2) Production of Polarizing Layer According to Example 1 of JP-A-2001-141926, a circumferential speed difference was given between two pairs of nip rolls, and the film was stretched in the longitudinal direction to produce a polarizing layer having a thickness of 20 μm.
(3) Bonding Two sheets were selected from the polarizing layer thus obtained and the saponified stretched cellulose acylate film, and the polarizing layer was sandwiched between them. Thereafter, PVA (manufactured by Kuraray Co., Ltd., PVA-117H) 3% aqueous solution is used as an adhesive, and the polarizing axis and the cellulose acylate film are laminated so that the longitudinal direction thereof is 90 °, which is disclosed in JP 2000-154261 A The 20-inch VA liquid crystal display device shown in FIGS. 2 to 9 was attached to a liquid crystal display device under conditions of 25 ° C. and relative humidity 60%. When the cellulose acylate films of Examples 1 to 7 were used, good display performance with little light leakage and uneven color was obtained. Further, when 1000 hours passed at 60 ° C. and 90% relative humidity, those using the stretched cellulose acylate films of Examples 1 to 7 obtained good display performance with little light leakage and uneven color.
Moreover, according to Example 1 of Unexamined-Japanese-Patent No. 2002-86554, although the polarizing plate extended | stretched so that the extending | stretching axis | shaft might become 45 degrees diagonally using the tenter, it produced similarly using the stretched cellulose acylate film of Examples 1-7. As above, good results were obtained.

2-2) Preparation of optical compensation film Instead of the cellulose acetate film coated with the liquid crystal layer of Example 1 of JP-A-11-316378, the above-mentioned saponified stretched cellulose acylate film was used. The bend-aligned liquid crystal cell described in Example 9 of Open 2002-62431 was attached under conditions of 25 ° C. and 60% relative humidity. Those using Examples 1 to 7 exhibited good display performance with little light leakage and color unevenness and little change in contrast. Further, when 1000 hours were passed at 60 ° C. and 90% relative humidity, those using Examples 1 to 7 obtained good display performance with little light leakage and color unevenness.

Further, in place of the cellulose acetate film coated with the liquid crystal layer of Example 1 of JP-A-7-333433, an optical compensation filter film was prepared by changing to the stretched cellulose acylate film (Examples 1 to 7) of the present invention. In addition, a good optical compensation film could be produced.
Further, a polarizing plate and a retardation polarizing plate using the cellulose acylate films of Examples 1 to 7 are the liquid crystal display device described in Example 1 of Japanese Patent Laid-Open No. 10-48420, and Japanese Patent Laid-Open No. 9-26572. An optically anisotropic layer containing discotic liquid crystal molecules described in Example 1, an alignment film coated with polyvinyl alcohol, a 20-inch VA liquid crystal display device described in FIGS. 2 to 9 of JP-A-2000-154261, When used in the 20-inch OCB type liquid crystal display device described in FIGS. 10 to 15 of JP-A No. 2000-154261 and the IPS type liquid crystal display device shown in FIG. 11 of JP-A No. 2004-12731, a good liquid crystal display device is obtained. Obtained.

2-3) Production of Low Reflective Film When a low reflective film was produced using the stretched cellulose acylate film of Examples 1 to 7 according to Example 47 of the Japan Institute of Invention and Innovation (public technical number 2001-1745), it was good. Optical performance was obtained.
Furthermore, a low reflection film using the stretched cellulose acylate film of Examples 1 to 7 is a liquid crystal display device described in Example 1 of JP-A No. 10-48420, and FIGS. 2 to 9 of JP-A No. 2000-154261. The 20-inch VA type liquid crystal display device described in 1) and the 20-inch OCB type liquid crystal display device shown in FIGS. A display device was obtained.

  According to the production method of the present invention, a cellulose acylate film having excellent optical properties can be produced. In particular, it is possible to produce a stretched cellulose acylate film suitable for use in a liquid crystal display device in which the liquid crystal display performance such as light leakage and color unevenness does not deteriorate even after exposure for 1000 hours in an environment of 60 ° C. and 90% relative humidity. . Therefore, the present invention is a useful invention with high industrial applicability.

Claims (2)

A film forming step of casting a cellulose acylate solution on a support and evaporating a part of the solvent in the cellulose acylate solution to form a cellulose acylate film; and the cellulose acylate film from the support A peeling step for peeling, and a stretching step for stretching the cellulose acylate film in the width direction,
In the stretching step, when the residual amount of the solvent represented by the following formula (1) of the cellulose acylate film after peeling from the support is 15% by mass, the following formulas (2), (3) and (4 The stretched cellulose acylate film is stretched in the width direction so that the stretch ratio represented by) is 10% to 90%.
Residual amount of solvent (% by mass) = (M−N) × 100 / N (1)
(M is the mass of the cellulose acylate film at the time of stretching, and N means the mass after drying the cellulose acylate film at 120 ° C. for 3 hours.)
Stretch ratio (%) = stretch ratio × 100 / maximum stretch ratio (2)
5% ≦ maximum stretching ratio ≦ 250% Formula (3)
Stretch ratio = [(width dimension after stretching in the width direction) − (width dimension in the unstretched state after peeling from the support)] × 100 / [in the unstretched state after peeling from the support] Width dimension] ... Formula (4)   A stretched cellulose acylate film produced by the method for producing a stretched cellulose acylate according to claim 1.