JP2006249418A - Cellulose acylate film and polarizing plate, retardation film, optical compensation film, antireflection film using the same, and image displaying device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cellulose acylate film remarkably eliminating optical irregularities on corner parts (frame irregularity) of a liquid crystal display device, used in protective film for a high quality polarizing plate and retardation film, and a method for producing the same. <P>SOLUTION: The invention relates to the cellulose acylate film having 100-150°C of Tg in dried state and 60-110°C of Tg in water absorbed state and obtained by drawing 10-250% in at least one direction. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a cellulose acylate film with little frame unevenness and good optical performance, and a high-quality polarizing plate, retardation film, optical compensation film, antireflection film and image display device using the cellulose acylate film About.

Cellulose ester films are used as a support for photographic photosensitive materials because of their transparency, toughness and optical isotropy, and are also suitable for image display devices such as liquid crystal display devices and organic EL display devices. Its application has been expanded as a film. As an optical film for a liquid crystal display device, STN (Super Twisted) is used after being used as a protective film for a polarizing plate or by stretching to develop in-plane retardation (Re) and thickness direction retardation (Rth). Nematic) is used as a retardation film for liquid crystal display devices.

  On the other hand, with the recent development of VA (Vertical Alignment) type and OCB (Optical Compensated Bend) type display elements that require higher Re and Rth phase differences than STN type, letter An optical film material excellent in development of the foundation has been required.

As a novel optical film material to meet such demands, a mixed ester solution of cellulose acetyl group and propionyl group (cellulose mixed acylate such as cellulose acetate propionate) is cast on a support, A cellulose acylate film produced by a solution casting method in which a part of the film is evaporated and then peeled off from the support is proposed (Patent Document 1).
Since cellulose acylate has a lower melting temperature than cellulose acetate, it has also been proposed to melt-form cellulose acetate butyrate and cellulose acetate propionate and use them as an optical film (Patent Document 2). Melt film formation does not use an organic solvent during film formation, and therefore has the advantage that the steps of dissolution and drying can be omitted and the burden on the environment is less than that of solution film formation.

  Since such a cellulose acylate film has an appropriate water vapor transmission rate, it is directly bonded to a polarizing film mainly composed of polyvinyl alcohol by immersing it in an alkaline aqueous solution to saponify and hydrophilize the surface. It can be used as a protective film and retardation film. Such a protective film for the polarizing plate is disposed between the polarizing film and the liquid crystal cell in the liquid crystal display device. For this reason, the optical characteristic of a protective film has big influence on the visibility of a liquid crystal display device. With the recent widening of the viewing angle and higher image quality of liquid crystal display devices, there is a need for improved compensation for phase difference, and there is also a need to reduce the effect on optical properties with respect to temperature and humidity changes. Yes.

However, in the methods disclosed in Patent Document 1 and Patent Document 2, the expression range of Re and Rth is narrow, and the Re value and Rth value cannot be controlled within the preferable ranges, respectively, and liquid crystal displays such as VA and OCB are displayed. It has been found that there is a problem that sufficient optical compensation cannot be performed in the apparatus. Further, in a liquid crystal display device incorporating a polarizing plate in which a cellulose acylate film prepared by the method disclosed in Patent Document 1 and Patent Document 2 is bonded to a polarizing film, optical unevenness occurs at the edge of the corner portion. This phenomenon (common name, picture frame or picture frame unevenness) occurs, and this optical non-uniformity has become a big problem with the recent increase in the screen size of liquid crystal display devices.
JP 2001-188128 A JP 2000-352620 A

The first object of the present invention is to produce cellulose having a wide range of optical characteristics of Re and Rth, and capable of controlling the Re value and the Rth value within a preferable range according to the liquid crystal mode such as OCB and VA. It is to provide an acylate film.
A second object of the present invention is to provide a protective film and retardation film for a polarizing plate that can prevent optical unevenness (also referred to as frame or frame unevenness) from occurring at the edge of the corner portion of a liquid crystal display device. It is in providing the cellulose acylate film used for this. Another object of the present invention is to provide a high-quality retardation film, polarizing plate, optical compensation film, antireflection film and image display device using the cellulose acylate film.

The above object of the present invention has been achieved by the present invention having the following constitution.
[1] A cellulose acylate film in which a cellulose acylate film formed by solution casting or melt casting is stretched by 10% to 250% in at least one of a longitudinal direction and a transverse direction,
The glass transition temperature in the dry state of the film is 100 ° C to 150 ° C, and
A cellulose acylate film having a glass transition temperature of 60 ° C to 110 ° C after the film is immersed in pure water at 25 ° C for 24 hours.
[2] The cellulose acylate film according to [1], wherein a linear thermal expansion coefficient at 25 to 80 ° C. is 5 to 150 ppm / ° C.
[3] The absolute value of the dimensional change rate before and after leaving the film in an environment of 60 ° C. and 90% relative humidity for 500 hours is 0% to 0.5% in both the vertical and horizontal directions of the film, and is slow. The cellulose acylate film according to [1] or [2], wherein the absolute value of the dimensional change rate in the phase axis direction is smaller than the absolute value of the dimensional change rate in the fast axis direction.
[4] The cellulose acylate film according to any one of [1] to [3], which has a photoelastic coefficient of 1 × 10 ^{−7 to} 25 × 10 ⁻⁷ cm ² / kgf.
[5] Any one of [1] to [4], wherein the cellulose acylate has two or more acylate groups having 2 to 6 carbon atoms and satisfies the following formulas (A) to (C): The cellulose acylate film described in 1.
Formula (A): 2.5 ≦ X + Y ≦ 3.0
Formula (B): 0 ≦ X ≦ 2.5
Formula (C): 0.3 ≦ Y <3
(In the above formula, X represents the substitution degree of the acetyl group, and Y represents the total substitution degree of the acyl group having 3 to 6 carbon atoms.)
[6] Contains at least one compound having two or more aromatic rings and a molecular weight of 200 to 3000 and a melting point of 50 ° C. to 250 ° C. in an amount of 0.1% by mass to 20% by mass with respect to cellulose acylate. The cellulose acylate film according to any one of [1] to [5], wherein:
[7] The cellulose acylate film according to any one of [1] to [6], wherein the following formulas (1) to (3) are satisfied.
Formula (1): 0 ≦ Re ≦ 300
Formula (2): 10 ≦ Rth ≦ 500
Formula (3): 1 ≦ Rth / Re ≦ 10
(In the above formula, Re is the retardation in the film plane at a wavelength of 590 nm, and Rth is the retardation in the thickness direction of the film at a wavelength of 590 nm)
[8] The difference between Re at 25 ° C./relative humidity 10% and Re at 25 ° C./relative humidity 80% is 15 nm or less, Rth at 25 ° C./relative humidity 10% and Rth at 25 ° C./relative humidity 80% [1] to 25 nm or less (where Re is retardation in the film surface at a wavelength of 590 nm, and Rth is retardation in the thickness direction of the film at a wavelength of 590 nm). [7] The cellulose acylate film according to any one of [7].
[9] The cellulose acylate film according to any one of [1] to [8], wherein the cellulose acylate film is melt-formed using a touch roll.
[10] The cellulose acylate film-like material is stretched by 10% to 250% in at least one of the longitudinal direction and the transverse direction in a state where the residual solvent amount is 1% by mass or less, and further with respect to the stretching ratio. The cellulose acylate film according to any one of [1] to [9], which is obtained by relaxing in the stretching direction at a ratio of 1% to 40%.

[11] A polarizing plate using one or more cellulose acylate films according to any one of [1] to [10].
[12] A retardation film using one or more cellulose acylate films according to any one of [1] to [10].
[13] An optical compensation film using one or more cellulose acylate films according to any one of [1] to [10].
[14] An antireflection film using one or more cellulose acylate films according to any one of [1] to [10].
[15] The cellulose acylate film according to any one of [1] to [10], the polarizing plate according to [11], the retardation film according to [12], the optical compensation film according to [13], and An image display device formed by using one or more films selected from the group consisting of the antireflection films according to [14].

[16] The cellulose acylate film-like product is obtained by heat-setting after stretching and further cooling at a slow cooling rate of 1 ° C./min to 50 ° C./min in a state where tension is applied. The cellulose acylate film according to any one of [1] to [10].
[17] A polarizing plate comprising a polarizing film and two protective films sandwiching the polarizing film, wherein at least one of the two protective films is the cellulose according to any one of [1] to [10] A polarizing plate, which is an acylate film or the retardation film according to [12].
[18] An optically anisotropic layer formed by aligning a liquid crystalline compound on the cellulose acylate film according to any one of [1] to [10] or the retardation film according to [12] An optical compensation film characterized by
[19] An antireflection film comprising an antireflection layer on the cellulose acylate film according to any one of [1] to [10] or the retardation film according to [12].

  The cellulose acylate film of the present invention has a wide expression range of Re and Rth, which are optical characteristics, and can control the Re value and the Rth value within preferable ranges, respectively. For this reason, if this invention is used, according to liquid crystal modes, such as OCB and VA, Re value and Rth value are simultaneously controlled to a preferable range, and the film excellent in optical performance can be provided. The film can be used as a protective film / retardation film for a polarizing plate, etc., and can eliminate frame unevenness that occurs in a corner portion of a liquid crystal display device due to variations in temperature and humidity. In addition to the high-quality retardation film and polarizing plate, an optical compensation film and an antireflection film can be provided using the cellulose acylate film of the present invention, and an image display device using these films can be provided. Can be provided. In particular, if an elliptically polarizing plate having a retardation plate on one side of the polarizing film and a protective film on the other side is used, the contrast of the front and left, right, left, top, bottom, wide viewing angles is increased without increasing the thickness of the liquid crystal display device. be able to.

  Hereinafter, the cellulose acylate film of the present invention will be described in detail. The description of the constituent elements described below may be made based on typical embodiments of the present invention, but the present invention is not limited to such embodiments. In the present specification, a numerical range represented by using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.

(Control of frame unevenness)
One of the features of the present invention is that it is possible to eliminate frame unevenness that occurs in a corner portion of a liquid crystal display device. In this specification, “frame unevenness” means that when the phase difference plate is attached to a liquid crystal display (LCD) to display the entire screen in black, immediately after the power is turned on, the periphery of the liquid crystal display has a whitish light leak. Refers to the phenomenon. As a result of the analysis of the occurrence mechanism of the frame unevenness by the present inventors, the phase difference plate rises in temperature due to changes in the use environment, turning on the thermal power, etc., causing dimensional distortion due to expansion or contraction, and stress is applied to the phase difference plate, In particular, it has been found that light leakage at the corner portion occurs during black display due to a change in retardation caused by a large stress generated at the corner portion of the liquid crystal display device. In particular, a retardation film (optical compensation sheet) has a problem in durability, and a phase difference is likely to occur due to distortion such as heat, and this phase difference also causes frame-shaped light leakage (increased transmittance) in the liquid crystal display device. It has been found that the display quality of the liquid crystal display device is lowered.

  As a result of intensive studies to suppress the occurrence of retardation and retardation due to such distortion, the present inventors have determined that the glass transition temperature in the dry state of the film (meaning that the equilibrium moisture content is 1% or less). Is a stretched cellulose acylate film having a glass transition temperature of 60 ° C. to 110 ° C. after being immersed in pure water at 25 ° C. for 24 hours, the durability is high. The present inventors have found that frame unevenness due to heat and other distortions can be suppressed. That is, as in the present invention, a cellulose acylate film having a high glass transition temperature in a dry state or a glass transition temperature in a water absorption state has a low linear thermal expansion coefficient and photoelasticity and is difficult to change in dimensions. Will stop working. When the dimension in one direction is fixed in this manner, the thermal dimension change and wet heat dimension change in the other direction are also suppressed, and as a result, the frame unevenness is considered to be reduced. As described below, the effect of suppressing such frame unevenness can be further increased by controlling the dimensional change rate, linear thermal expansion coefficient, and photoelasticity of cellulose acylate with respect to temperature and humidity changes.

<Characteristics of cellulose acylate film of the present invention>
The glass transition temperature (Tg) in the dry state of the cellulose acylate film of the present invention is 100 ° C. to 150 ° C., preferably 105 ° C. to 145 ° C., more preferably 110 ° C. to 145 ° C., and particularly preferably. 115 ° C to 140 ° C. When Tg is lower than 100 ° C., heat resistance and dimensional stability are lowered, and frame unevenness is likely to occur. On the other hand, a Tg higher than 150 ° C. is not preferable because the glass transition temperature of the film is too high and the melt flowability and stretchability are lowered.
Moreover, after immersing the cellulose acylate film of this invention for 24 hours in 25 degreeC pure water, Tg measured in the state which absorbed water is 60 to 110 degreeC, 65 to 110 degreeC is preferable, and 70 to 110 degreeC is preferable. C. is most preferred.
In order to make Tg in the dry state and water absorption state of the present invention within the above ranges, it is preferable to appropriately adjust the prescription of cellulose acylate, film-forming stretching conditions, and the like. Specifically, adjustment of the prescription of cellulose acylate includes control of the degree of substitution and the ratio of substituents, selection of additive types, control of the total amount added, and the like. Examples of the adjustment of the film-forming stretching condition include control of the residual solvent amount, stretching ratio, relaxation rate, heat setting treatment, cooling rate, and the like.

In the cellulose acylate film of the present invention, the absolute value of the dimensional change rate before and after being left in an environment of 60 ° C. and 90% relative humidity for 500 hours is 0% to 0.5% in both the vertical and horizontal directions of the film. Preferably, it is 0% to 0.4%, more preferably 0% to 0.3%, and most preferably 0% to 0.2%. In order to set the absolute value of the dimensional change rate to 0% to 0.5%, it is preferable to appropriately control the prescription of the cellulose acylate film (film-like material), the film forming conditions described below, and the stretching conditions.
In the cellulose acylate film of the present invention, the absolute value of the dimensional change rate in the slow axis direction is preferably smaller than the absolute value of the dimensional change rate in the fast axis direction. The ratio of the absolute value of the dimensional change rate in the slow axis direction and the absolute value of the dimensional change rate in the fast axis direction is preferably 0.5 to 0.99, more preferably 0.70 to 0.98. Yes, more preferably from 0.75 to 0.95. By adjusting the ratio to 0.5 to 0.99, the frame unevenness can be more effectively reduced. In order to adjust the ratio to 0.5 to 0.99, it is preferable to appropriately control the stretching conditions of the cellulose acylate film (film-like product) described later, the stretching ratio in the longitudinal direction and the transverse direction, and the like.

  The cellulose acylate film of the present invention preferably has a thermal expansion coefficient of 5 to 150 ppm / ° C. at 25 to 80 ° C., more preferably 5 to 140 ppm / ° C., and 5 to 130 ppm / ° C. Is more preferable.

The photoelastic coefficient of the cellulose acylate film of the present invention is preferably 1 × 10 ^{−7 to} 25 × 10 ⁻⁷ cm ² / kgf, and is preferably 1 × 10 ^{−7 to} 20 × 10 ⁻⁷ cm ² / kgf. More preferred is 1 × 10 ⁻⁷ to 18 × 10 ⁻⁷ cm ² / kgf, still more preferred is 1 × 10 ⁻⁷ to 15 × 10 ⁻⁷ cm ² / kgf.
In order to bring the linear thermal expansion coefficient and the photoelasticity of the cellulose acylate film of the present invention into the above ranges, it is preferable to appropriately control the prescription of cellulose acylate, the film forming conditions and the stretching conditions described later, and the like.

<Structure of cellulose acylate>
First, the cellulose acylate used in the present invention (hereinafter referred to as the cellulose acylate of the present invention) will be described in detail.
The glucose unit which constitutes cellulose and has β-1,4 bonds 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. In this application, the degree of substitution is used to indicate the esterification rate of the hydroxyl group. The degree of substitution is the sum of the proportions of esterification of cellulose for each of the 2nd, 3rd and 6th positions (degree of substitution 1 when 100% esterified). The degree of substitution is 3.
In the cellulose acylate of the present invention, the substitution degree of each hydroxyl group at the 2-position, 3-position and 6-position of cellulose is not particularly limited. However, since the degree of substitution at the 6-position is preferably 0.8 or more, more preferably 0.85 or more, and particularly preferably 0.90 or more, cellulose acylate having such a high solubility has a high solubility. If cellulose acylate having a high degree of substitution is used, a particularly good solution for a non-chlorine organic solvent can be prepared.

  The cellulose acylate of the present invention preferably has two or more types of acyl groups. The acyl group preferably has 2 to 6 carbon atoms, and the substitution degree by the acyl group (referred to as acyl substitution degree) is preferably 2.5 or more and less than 3.0. The acyl group may further have a substituent.

The cellulose acylate of the present invention preferably has an acyl substitution degree satisfying the following formula. Here, X represents the substitution degree of the acetyl group, and Y represents the total substitution degree of the propionyl group, butyryl group, pentanoyl group, and hexanoyl group.
2.5 ≦ X + Y ≦ 3.0
0 ≦ X ≦ 2.5
0.3 ≦ Y ≦ 3
More preferably,
2.5 ≦ X + Y ≦ 2.99
0 ≦ X ≦ 2.0
0.5 ≦ Y ≦ 2.95
More preferably, 2.5 ≦ X + Y ≦ 2.95
0 ≦ X ≦ 1.5
0.8 ≦ Y ≦ 2.95

  As in the above formula, it is preferable to reduce the degree of substitution of the acetyl group and increase the total degree of substitution of the acyl group having 3 to 6 carbon atoms because the crystal melting temperature (Tm) can be lowered. That is, it becomes a cellulose acylate suitable for melt film formation.

The degree of acyl substitution is determined by a method according to ASTM D-817-91, a method of quantifying the carboxylic acid or its salt liberated by complete hydrolysis of cellulose acylate by gas chromatography or high-performance liquid chromatography, ¹ H- It can be determined by using NMR or ¹³ C-NMR methods alone or in combination.

  In the present invention, two or more different cellulose acylates may be mixed and used, or the layers may be used separately.

<Production method of cellulose acylate>
Next, the manufacturing method of the cellulose acylate of this invention is demonstrated in detail. The raw material cotton and the synthetic method of the cellulose acylate of the present invention are also described in detail in pages 7 to 12 of the Japan Institute of Invention and Technology (public technical number 2001-1745, published on March 15, 2001, Japan Society of Invention). Has been.

(Raw material and pretreatment)
As a cellulose raw material used as a raw material for cellulose acylate, a cellulose raw material derived from hardwood pulp, softwood pulp, or cotton linter is preferably used. As the cellulose raw material, it is preferable to use a high-purity material having an α-cellulose content of 92 mass% to 99.9 mass%.
In the case where the cellulose raw material is in the form of a film or a lump, it is preferably pulverized in advance. Moreover, it is preferable that crushing is progressing until the form of the cellulose raw material becomes a fine powder-feather shape.

(activation)
Prior to acylation, the cellulose raw material is preferably subjected to a treatment (activation) in contact with an activator. As the activator, carboxylic acid or water can be used, but when water is used, carboxylic acid is used to perform dehydration by adding excess acid anhydride after activation or to replace water. And a step of adjusting the acylation conditions. The activator may be added by adjusting to any temperature, and the addition method can be selected from methods such as spraying, dropping and dipping.

  Preferred carboxylic acids as activators are carboxylic acids having 2 to 7 carbon atoms (for example, acetic acid, propionic acid, butyric acid, 2-methylpropionic acid, valeric acid, 3-methylbutyric acid, 2-methylbutyric acid, 2,2- Dimethylpropionic acid (pivalic acid), hexanoic acid, 2-methylvaleric acid, 3-methylvaleric acid, 4-methylvaleric acid, 2,2-dimethylbutyric acid, 2,3-dimethylbutyric acid, 3,3-dimethylbutyric acid, Cyclopentanecarboxylic acid, heptanoic acid, cyclohexanecarboxylic acid, benzoic acid, etc.), more preferably acetic acid, propionic acid, or butyric acid, and particularly preferably acetic acid.

  At the time of activation, an acylation catalyst such as sulfuric acid can be further added as necessary. However, when a strong acid such as sulfuric acid is added, depolymerization may be promoted. Therefore, the addition amount is preferably limited to about 0.1% by mass to 10% by mass with respect to cellulose. Two or more kinds of activators may be used in combination, or an acid anhydride of a carboxylic acid having 2 to 7 carbon atoms may be added.

  The addition amount of the activator is preferably 5% by mass or more, more preferably 10% by mass or more, and particularly preferably 30% by mass or more based on cellulose. It is preferable that the amount of the activator is equal to or more than the lower limit value because problems such as a decrease in the degree of activation of cellulose do not occur. The upper limit of the addition amount of the activator is not particularly limited as long as productivity is not lowered, but it is preferably 100 times or less, more preferably 20 times or less, and 10 times or less by mass with respect to cellulose. It is particularly preferred that Activation may be carried out by adding a large excess of activator to cellulose, and then the amount of the activator may be reduced by performing operations such as filtration, air drying, heat drying, distillation under reduced pressure, and solvent substitution.

  The activation time is preferably 20 minutes or more, and the upper limit is not particularly limited as long as it does not affect the productivity, but is preferably 72 hours or less, more preferably 24 hours or less, particularly preferably. Is 12 hours or less. The activation temperature is preferably 0 ° C to 90 ° C, more preferably 15 ° C to 80 ° C, and particularly preferably 20 ° C to 60 ° C. The step of activating cellulose can also be performed under pressure or reduced pressure. Moreover, you may use electromagnetic waves, such as a microwave and infrared rays, as a heating means.

(Acylation)
When cellulose acylate is produced, it is preferable to acylate the hydroxyl group of cellulose by adding an acid anhydride of carboxylic acid to cellulose and reacting with Bronsted acid or Lewis acid as a catalyst.
The synthesis of cellulose acylate having a high degree of substitution at the 6-position is described in JP-A Nos. 11-5851, 2002-212338, 2002-338601, and the like.
Other synthetic methods of cellulose acylate include the presence of a base (sodium hydroxide, potassium hydroxide, barium hydroxide, sodium carbonate, pyridine, triethylamine, tert-butoxy potassium, sodium methoxide, sodium ethoxide, etc.). , A method of reacting with a carboxylic acid anhydride or a carboxylic acid halide, a method using a mixed acid anhydride (such as a mixed anhydride of carboxylic acid / trifluoroacetic acid, a mixed anhydride of carboxylic acid / methanesulfonic acid, etc.) as an acylating agent In particular, the latter method is effective when an acyl group having a large number of carbon atoms or an acyl group that is difficult to be acylated by a carboxylic acid anhydride-acetic acid-sulfuric acid catalyst is introduced.
As a method for obtaining a cellulose mixed acylate, a method of reacting two carboxylic acid anhydrides as an acylating agent by mixing or sequentially adding them, a mixed acid anhydride of two carboxylic acids (for example, acetic acid / propionic acid mixed acid anhydride) Product), mixed acid anhydride (for example, acetic acid / propionic acid mixed acid anhydride) in the reaction system using carboxylic acid and another carboxylic acid anhydride (for example, acetic acid and propionic acid anhydride) as raw materials And a method in which cellulose acylate having a degree of substitution of less than 3 is synthesized once, and a remaining hydroxyl group is further acylated using an acid anhydride or an acid halide. .

(Acid anhydride)
Preferred as the carboxylic acid anhydride are those having 2 to 7 carbon atoms as the carboxylic acid. For example, acetic anhydride, propionic anhydride, butyric anhydride, 2-methylpropionic anhydride, Herbic anhydride, 3-methylbutyric anhydride, 2-methylbutyric anhydride, 2,2-dimethylpropionic anhydride (pivalic anhydride), hexanoic anhydride, 2-methylvaleric anhydride, 3-methyl Valeric anhydride, 4-methylvaleric anhydride, 2,2-dimethylbutyric anhydride, 2,3-dimethylbutyric anhydride, 3,3-dimethylbutyric anhydride, cyclopentanecarboxylic anhydride, heptanoic anhydride Product, cyclohexanecarboxylic acid anhydride, benzoic acid anhydride, and the like. More preferred are acetic anhydride, propionic anhydride, butyric anhydride, valeric anhydride, hexanoic anhydride, heptanoic anhydride and the like, and particularly preferred are acetic anhydride, propionic anhydride, butyric acid. Anhydrous.

  For the purpose of preparing a mixed ester, it is preferable to use these acid anhydrides in combination. The mixing ratio is preferably determined according to the substitution ratio of the target mixed ester. The acid anhydride is usually added in excess equivalent to the cellulose. That is, it is preferable to add 1.2-50 equivalent with respect to the hydroxyl group of a cellulose, It is more preferable to add 1.5-30 equivalent, It is especially preferable to add 2-10 equivalent.

(catalyst)
It is preferable to use a Bronsted acid or a Lewis acid as the acylation catalyst used in the production of cellulose acylate. The definitions of Bronsted acid and Lewis acid are described in, for example, “Physical and Chemical Dictionary”, 5th edition (2000). Examples of preferable Bronsted acid include sulfuric acid, perchloric acid, phosphoric acid, methanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid and the like. Examples of preferred Lewis acids include zinc chloride, tin chloride, antimony chloride, magnesium chloride and the like.
As the catalyst, sulfuric acid or perchloric acid is more preferable, and sulfuric acid is particularly preferable. The preferable addition amount of a catalyst is 0.1-30 mass% with respect to a cellulose, More preferably, it is 1-15 mass%, Most preferably, it is 3-12 mass%.

(solvent)
In carrying out acylation, a solvent may be added for the purpose of adjusting viscosity, reaction rate, stirring property, acyl substitution ratio, and the like. As such a solvent, dichloromethane, chloroform, carboxylic acid, acetone, ethyl methyl ketone, toluene, dimethyl sulfoxide, sulfolane and the like can be used, but carboxylic acid is preferable, for example, a carboxylic acid having 2 to 7 carbon atoms. Acids {eg acetic acid, propionic acid, butyric acid, 2-methylpropionic acid, valeric acid, 3-methylbutyric acid, 2-methylbutyric acid, 2,2-dimethylpropionic acid (pivalic acid), hexanoic acid, 2-methylvaleric acid , 3-methylvaleric acid, 4-methylvaleric acid, 2,2-dimethylbutyric acid, 2,3-dimethylbutyric acid, 3,3-dimethylbutyric acid, cyclopentanecarboxylic acid} and the like. More preferably, acetic acid, propionic acid, butyric acid and the like can be mentioned. These solvents may be used as a mixture.

(Conditions for acylation)
When acylation is performed, an acid anhydride and a catalyst, and further, if necessary, a solvent may be mixed and then mixed with cellulose, or these may be separately mixed with cellulose. It is preferable to prepare a mixture of an acid anhydride and a catalyst or a mixture of an acid anhydride, a catalyst and a solvent as an acylating agent and then react with cellulose. In order to suppress a temperature rise in the reaction vessel due to heat of reaction during acylation, the acylating agent is preferably cooled in advance. The cooling temperature is preferably −50 ° C. to 20 ° C., more preferably −35 ° C. to 10 ° C., and particularly preferably −25 ° C. to 5 ° C. The acylating agent may be added in a liquid state or may be frozen and added as a crystal, flake or block solid.

  Further, the acylating agent may be added to the cellulose at once or dividedly. In addition, cellulose may be added to the acylating agent all at once or in divided portions. When the acylating agent is added in a plurality of times, an acylating agent having the same composition may be added, or a plurality of acylating agents having different compositions may be added. As a preferred example, 1) a mixture of acid anhydride and solvent is added first, then the catalyst is added, and 2) a mixture of part of acid anhydride, solvent and catalyst is added first, then the rest of the catalyst and Add solvent mixture 3) Add acid anhydride and solvent mixture first, then add catalyst and solvent mixture 4) Add solvent first, acid anhydride and catalyst mixture or acid For example, a mixture of an anhydride, a catalyst, and a solvent may be added.

  Although acylation of cellulose is an exothermic reaction, in the method for producing the cellulose acylate of the present invention, it is preferable that the maximum temperature reached during acylation is 50 ° C. or lower. If the reaction temperature is lower than this temperature, depolymerization proceeds and it is preferable because there is no inconvenience such as difficulty in obtaining a cellulose acylate having a polymerization degree suitable for the use of the present invention. The maximum temperature reached during acylation is preferably 45 ° C. or lower, more preferably 40 ° C. or lower, and particularly preferably 35 ° C. or lower. The reaction temperature may be controlled using a temperature control device or may be controlled by the initial temperature of the acylating agent. The reaction temperature can also be controlled by reducing the pressure of the reaction vessel and the heat of vaporization of the liquid component in the reaction system. Since the exotherm during the acylation is large in the initial stage of the reaction, it is possible to control such as cooling in the initial stage of the reaction and heating thereafter. The end point of acylation can be determined by means such as light transmittance, solution viscosity, temperature change of the reaction system, solubility of the reaction product in an organic solvent, and observation with a polarizing microscope.

  The minimum reaction temperature is preferably −50 ° C. or higher, more preferably −30 ° C. or higher, and particularly preferably −20 ° C. or higher. A preferable acylation time is 0.5 to 24 hours, more preferably 1 to 12 hours, and particularly preferably 1.5 to 6 hours. If it is 0.5 hours or more, the reaction is likely to proceed sufficiently, and if it is within 24 hours, it is industrially easy to use.

(Reaction terminator)
In the method for producing cellulose acylate used in the present invention, it is preferable to add a reaction terminator after the acylation reaction.
The reaction terminator may be any as long as it decomposes the acid anhydride, and preferred examples include water, alcohol (eg, ethanol, methanol, propanol, isopropyl alcohol, etc.) or a composition containing these. And so on. Moreover, the reaction terminator may contain the below-mentioned neutralizing agent. Upon addition of the reaction terminator, a large exotherm exceeding the cooling capacity of the reactor may occur, which may cause the degree of polymerization of the cellulose acylate to decrease, or the cellulose acylate may precipitate in an undesired form. In order to avoid such inconveniences, it is preferable to add a mixture of carboxylic acid such as acetic acid, propionic acid, butyric acid and water rather than directly adding water or alcohol, and acetic acid is particularly preferable as the carboxylic acid. The composition ratio of the carboxylic acid and water can be set to an arbitrary ratio, but the water content is 5% by mass to 80% by mass, further 10% by mass to 60% by mass, particularly 15% by mass to 50% by mass. It is preferable to be within the range.

  The method for adding the reaction terminator is not particularly limited. The reaction terminator may be added to the acylation reaction vessel, or the reactant may be added to the reaction terminator vessel. The reaction terminator is preferably added over 3 minutes to 3 hours. If the addition time of the reaction terminator is 3 minutes or more, the exotherm becomes too large, causing a decrease in the degree of polymerization, insufficient hydrolysis of the acid anhydride, and reducing the stability of cellulose acylate. This is preferable because there is no inconvenience. Moreover, it is preferable that the addition time of the reaction terminator is 3 hours or less because problems such as industrial productivity decrease do not occur. The addition time of the reaction terminator is preferably 4 minutes to 2 hours, more preferably 5 minutes to 1 hour, and particularly preferably 10 minutes to 45 minutes. When adding the reaction terminator, the reaction vessel may or may not be cooled, but for the purpose of suppressing depolymerization, it is preferable to cool the reaction vessel to suppress the temperature rise. It is also preferable to cool the reaction terminator.

(Neutralizer)
Hydrolysis of excess carboxylic anhydride remaining in the system after the acylation reaction stopping step or acylation reaction stopping step, neutralization of some or all of the carboxylic acid and esterification catalyst, residual sulfate radical amount In order to adjust the amount of residual metal and the like, a neutralizing agent or a solution thereof may be added.
Preferred examples of the neutralizing agent include ammonium, organic quaternary ammonium (eg, tetramethylammonium, tetraethylammonium, tetrabutylammonium, diisopropyldiethylammonium, etc.), alkali metals (preferably lithium, sodium, potassium, rubidium, cesium) More preferably lithium, sodium, potassium, particularly preferably sodium, potassium), group 2 elements (preferably beryllium, calcium, magnesium, strontium, barium, particularly preferably calcium, magnesium), 3-12 Carbonates of group metals (eg, iron, chromium, nickel, copper, lead, zinc, molybdenum, niobium, titanium, etc.) or elements of group 13-15 (eg, aluminum, tin, antimony, etc.) Bicarbonate, organic acid salt (eg acetate, propionate, butyrate, benzoate, phthalate, hydrogen phthalate, citrate, tartrate, etc.), phosphate, hydroxide or An oxide etc. can be mentioned. These neutralizing agents may be used in combination, and may form mixed salts (for example, magnesium acetate propionate, potassium sodium tartrate, etc.). Further, when the anion of these neutralizing agents is divalent or higher, a hydrogen salt (for example, sodium hydrogen carbonate, potassium hydrogen carbonate, sodium dihydrogen phosphate, magnesium hydrogen phosphate, etc.) may be formed.
More preferably, the neutralizing agent is a carbonate, hydrogen carbonate, organic acid salt, hydroxide or oxide of an alkali metal or a group 2 element, and particularly preferably sodium, potassium, magnesium or calcium carbonate. Salt, bicarbonate, acetate or hydroxide.
As a solvent for the neutralizing agent, water, alcohol (eg, ethanol, methanol, propanol, isopropyl alcohol, etc.), organic acid (eg, acetic acid, propionic acid, butyric acid, etc.), ketone (eg, acetone, ethyl methyl ketone, etc.), Preferable examples include polar solvents such as dimethyl sulfoxide and mixed solvents thereof.

(Partial hydrolysis)
The cellulose acylate thus obtained has a total degree of substitution close to 3. However, for the purpose of obtaining a desired degree of substitution, a small amount of catalyst (generally, acylation of remaining sulfuric acid or the like) is performed. (Catalyst) and water in the presence of 20 to 90 ° C. for several minutes to several days to partially hydrolyze the ester bond and reduce the total degree of substitution of cellulose acylate to the desired degree (so-called Aging) is generally performed. Since the cellulose sulfate ester is also hydrolyzed during the partial hydrolysis, the amount of sulfate ester bound to the cellulose can be reduced by adjusting the hydrolysis conditions.

(Stop partial hydrolysis)
When the desired cellulose acylate is obtained, it is preferable to completely neutralize the catalyst remaining in the system using the neutralizing agent as described above or a solution thereof to stop partial hydrolysis. . By adding a neutralizing agent (for example, magnesium carbonate, magnesium acetate, etc.) that generates a salt that is poorly soluble in the reaction solution, a catalyst (for example, sulfate ester) bound to the solution or to cellulose is effectively removed. It is also preferable to remove.

(Filtration)
It is preferable to filter the reaction mixture (dope) for the purpose of removing or reducing unreacted substances, hardly soluble salts, and other foreign matters in cellulose acylate. Filtration may be performed at any stage between the completion of acylation and reprecipitation. For the purpose of controlling filtration pressure and handleability, it is also preferable to dilute with an appropriate solvent prior to filtration.

(Reprecipitation)
The cellulose acylate solution thus obtained is mixed in a poor solvent such as water or an aqueous solution of carboxylic acid (for example, acetic acid, propionic acid, etc.), or the poor solvent is mixed in the cellulose acylate solution. As a result, the cellulose acylate can be re-precipitated and the desired cellulose acylate can be obtained by washing and stabilizing treatment. Reprecipitation may be carried out continuously or batchwise by a fixed amount. It is also preferable to control the form and molecular weight distribution of the re-precipitated cellulose acylate by adjusting the concentration of the cellulose acylate solution and the composition of the poor solvent according to the substitution mode of the cellulose acylate or the degree of polymerization.
In addition, for the purpose of improving the purification effect, adjusting the molecular weight distribution and the apparent density, the cellulose acylate once re-precipitated is dissolved again in the good solvent (for example, acetic acid or acetone), and the poor solvent (for example, , Water, etc.) may be performed once or a plurality of times as necessary.

(Washing)
The produced cellulose acylate is preferably washed. The washing solvent is not particularly limited as long as it has low cellulose acylate solubility and can remove impurities, but water or warm water is usually used. The temperature of the washing water is preferably 25 ° C to 100 ° C, more preferably 30 ° C to 90 ° C, and particularly preferably 40 ° C to 80 ° C. The washing treatment may be performed in a so-called batch system in which filtration and replacement of the washing liquid are repeated, or may be carried out using a continuous washing apparatus. It is also preferable to reuse the waste liquid generated in the reprecipitation and washing steps as a poor solvent in the reprecipitation step, or to recover and reuse a solvent such as carboxylic acid by means such as distillation.
The progress of washing may be traced by any means, but preferred examples include methods such as hydrogen ion concentration, ion chromatography, electrical conductivity, ICP, elemental analysis, and atomic absorption spectrum.
By such treatment, the catalyst (sulfuric acid, perchloric acid, trifluoroacetic acid, p-toluenesulfonic acid, methanesulfonic acid, zinc chloride, etc.) in the cellulose acylate, neutralizer (for example, calcium, magnesium, iron, Aluminum or zinc carbonates, acetates, hydroxides or oxides), reaction products of neutralizing agents with catalysts, carboxylic acids (eg acetic acid, propionic acid, butyric acid), reactions of neutralizing agents with carboxylic acids Can be removed, which is effective to increase the stability of cellulose acylate.

(Stabilization)
Cellulose acylate after washing with hot water treatment is weakly alkaline (for example, carbonates, bicarbonates such as sodium, potassium, calcium, magnesium, aluminum, etc.) in order to further improve the stability or reduce the carboxylic acid odor. It is also preferable to treat with an aqueous solution of hydroxide, oxide, etc.).
The amount of residual impurities is the metal content of the water used (the amount of metal ions contained as trace components in the water used for the washing water, etc.), the amount of the washing liquid, the washing temperature, the time, the stirring method, the washing container It can be controlled by the form and the composition and concentration of the stabilizer. In the present invention, conditions for acylation, partial hydrolysis, neutralization and washing are set so that the amount of residual sulfate radical (as the sulfur atom content) is 0 to 500 ppm. The amount of residual alkali metal and the amount of group 2 elements can be adjusted according to the conditions of partial hydrolysis, neutralization and washing.

(Dry)
In the present invention, in order to adjust the water content of the cellulose acylate to a preferable amount, it is preferable to dry the cellulose acylate. The drying method is not particularly limited as long as the desired moisture content can be obtained, but it is preferable that the drying method be performed efficiently by using means such as heating, air blowing, decompression, and stirring alone or in combination. The drying temperature is preferably 0 to 200 ° C, more preferably 40 to 180 ° C, and particularly preferably 50 to 160 ° C. The cellulose acylate of the present invention has a water content of preferably 2% by mass or less, more preferably 1% by mass or less, and particularly preferably 0.7% by mass or less.

(Form)
The cellulose acylate in the present invention can take various shapes such as particles, powders, fibers and lumps, but it is preferable that the raw materials for film production are particles or powders. Cellulose acylate may be pulverized or sieved for uniform particle size and improved handling. When the cellulose acylate is in the form of particles, 90% by mass or more of the particles used preferably have a particle size of 0.5 to 5 mm. Moreover, it is preferable that 50 mass% or more of the particle | grains to be used have a particle size of 1-4 mm. The cellulose acylate particles preferably have a shape as close to a sphere as possible. Moreover, the cellulose acylate particles of the present invention preferably have an apparent density of 0.5 to 1.3, more preferably 0.7 to 1.2, and particularly preferably 0.8 to 1.15. The method for measuring the apparent density is defined in JIS K-7365.
The cellulose acylate particles in the present invention preferably have an angle of repose of 10 to 70 degrees, more preferably 15 to 60 degrees, and particularly preferably 20 to 50 degrees.

(Degree of polymerization)
The degree of polymerization of the cellulose acylate preferably used in the present invention is an average degree of polymerization of 100 to 700, preferably 120 to 550, more preferably 120 to 500, and particularly preferably an average degree of polymerization of 130 to 400. The average degree of polymerization is determined by gel permeation chromatography (GPC) as described in Uda et al.'S intrinsic viscosity method (Kazuo Uda, Hideo Saito, Journal of Textile Science, Vol. 18, No. 1, pages 105-120, 1962). ) To measure the molecular weight distribution. Furthermore, the method for measuring the average degree of polymerization is described in detail in JP-A-9-95538.
In the present invention, the ratio of the weight average polymerization degree / number average polymerization degree by GPC of cellulose acylate is preferably 1.5 to 5.5, more preferably 1.5 to 5.0, It is especially preferable that it is 1.8-4.5.

(Fine foreign matter in cellulose acylate)
The fine foreign matters in cellulose acylate are derived from unreacted cellulose fibers. When this fine foreign matter remains in the optical film, it appears as a bright spot when the two polarizing plates are crossed Nicol and the optical film is sandwiched. This bright spot causes light leakage in the liquid crystal display device. Accordingly, it is preferable that the amount of fine foreign matter contained in the cellulose acylate is as small as possible. Specifically, the number of fine foreign matters is estimated as follows.

About 10 mg of sample is sandwiched between two glass slides with a size of 1 cm ^{2 and a} thickness of 150 μm.
This is melted so that a transparent thin film of cellulose acylate between the slide glasses has a thickness of about 50 μm. The thickness of the thin film of cellulose acylate may be obtained by subtracting the thickness of the original slide glass from the thickness of the two glass slides sandwiching the cellulose acylate thin film. In addition, what is necessary is just to convert later, when thickness differs greatly with 50 micrometers. The cellulose acylate thin film thus produced, which is sandwiched between the slide glasses, is observed with a microscope at an arbitrary 1 mm ² site, and the number of fine foreign matters per 1 mm ² × 50 μm = 5 × 10 ⁻² mm ³ is determined. Count. The number of fine foreign matters having a length of 10 μm or less observed at this time is 10 or less per 5 × 10 ⁻² mm ³ , preferably 5 or less, more preferably 2 or less, and most preferably 0. Although fine foreign matters having a length of 10 μm or more may be included, the number thereof is substantially proportional to the number of fine foreign matters having a length of 10 μm or less. Therefore, in the present invention, the fine foreign matters having a length of 10 μm or less are used as a reference.

(Residual sulfur content in cellulose acylate)
In the above cellulose acylate production method, when sulfuric acid is used as a catalyst, a sulfate ester may remain in the finally obtained cellulose acylate. This may affect the thermal stability of the cellulose acylate. In the present invention, the sulfur content is preferably from 0 to 100 ppm, preferably from 10 to 80 ppm, and more preferably from 10 to 60 ppm in terms of sulfur atom with respect to cellulose acylate.

(Melting point of cellulose acylate)
When forming a film by melt film formation using the cellulose acylate of the present invention, it is necessary to have a melting point suitable for practical use. If the melting point is too high, decomposition proceeds before melting. If it is too low, it cannot be used as a practical optical film. Accordingly, the melting point is preferably 160 ° C to 260 ° C, more preferably 160 ° C to 250 ° C, and most preferably 170 ° C to 240 ° C.

  These cellulose acylates may be used alone or in combination of two or more. Further, a polymer component other than cellulose acylate may be appropriately mixed. Moreover, the polymer component to be mixed is preferably one having excellent compatibility with the cellulose ester. The cellulose acylate in the present invention preferably has a transmittance of 80% or more, more preferably 90% or more, and particularly preferably 92% or more when formed into a film.

(Additive for cellulose acylate)
Although the additive used for the cellulose acylate of this invention is demonstrated in detail below, the additive which can be used by this invention is not limited to these.

1) Retardation increasing agent In order to adjust the retardation of the cellulose acetate film of the present invention, it is preferable to contain a retardation increasing agent. The retardation increasing agent means one that can increase the retardation of the film by containing the retardation increasing agent in the film.
The type of the retardation increasing agent is not particularly limited, but it is preferable to use an aromatic compound having at least two aromatic rings as the retardation increasing agent. The aromatic compound preferably has a molecular weight of 200 to 3000 and a melting point of 55 ° C to 250 ° C. The amount used is preferably 0.1% by mass to 20% by mass, more preferably 0.1% by mass to 20% by mass, and 0.5% by mass to 100% by mass of cellulose acetate. The content is more preferably 15% by mass, and particularly preferably 1% by mass to 10% by mass.
By adding these retardation increasing compounds, the Re and Rth expression areas of cellulose acylate are greatly improved, achieving the desired optical characteristics with a low draw ratio, and exhibiting the effect of suppressing frame unevenness. Can be made.

Two or more types of aromatic compounds may be used in combination as the aromatic compound having at least two aromatic rings. The aromatic ring of the aromatic compound here includes an aromatic hetero ring in addition to the aromatic hydrocarbon ring.
The aromatic hydrocarbon ring is particularly preferably a 6-membered ring (that is, a benzene ring). The aromatic heterocycle is generally an unsaturated heterocycle. The aromatic heterocycle is preferably a 5-membered ring, 6-membered ring or 7-membered ring, more preferably a 5-membered ring or 6-membered ring. Aromatic heterocycles generally have the most double bonds. As the hetero atom, a nitrogen atom, an oxygen atom and a sulfur atom are preferable, and a nitrogen atom is particularly preferable. Examples of aromatic heterocycles include furan ring, thiophene ring, pyrrole ring, oxazole ring, isoxazole ring, thiazole ring, isothiazole ring, imidazole ring, pyrazole ring, furazane ring, triazole ring, pyran ring, pyridine ring , Pyridazine ring, pyrimidine ring, pyrazine ring and 1,3,5-triazine ring. As the aromatic ring, benzene ring, furan ring, thiophene ring, pyrrole ring, oxazole ring, thiazole ring, imidazole ring, triazole ring, pyridine ring, pyrimidine ring, pyrazine ring and 1,3,5-triazine ring are preferable, More preferred are a benzene ring and a 1,3,5-triazine ring.

  The number of aromatic rings contained in the aromatic compound is preferably 2 to 20, more preferably 2 to 18, and most preferably 2 to 15. The bonding relationship between two aromatic rings can be classified into (a) when a condensed ring is formed, (b) when directly linked by a single bond, and (c) when linked via a linking group (for aromatic rings). , Spiro bonds cannot be formed). The connection relationship may be any of (a) to (c).

  Specific examples of preferable compounds as the retardation increasing agent include compounds described in paragraph numbers [0016] to [0107] of JP-A No. 2001-166144 and paragraph numbers [0007] to [0007] of JP-A No. 2002-296421. 0043] can be mentioned. Further, the following compounds in which two aromatic rings are connected by —COO— can also be preferably used.

  In addition, the following compounds in which three aromatic rings are connected by —COO— or —CONR′— can also be preferably used.

  In addition, compounds in which three arylamino groups are substituted on the following triazine derivatives can be preferably used.

  Furthermore, the compound in which many aromatic rings were connected linearly as follows can be illustrated.

  These compounds may be used alone or in combination.

  These compounds specifically exhibit the above effect on cellulose acylate. These compounds may be used alone or in combination. Two or more aromatic compounds may be used in combination. However, plasticizers (eg, phosphate ester compounds, phthalate ester compounds, glycolate ester compounds) and UV absorbers (eg, benzophenone compounds and benzotriazole compounds) do not provide such effects. .

2) Other additives In addition to cellulose acylate and the above-mentioned retardation increasing agent, the cellulose acylate composition of the present invention includes various additives (for example, antioxidant, deterioration) depending on the use in each preparation step. For example, an inhibitor, a matting agent, an ultraviolet ray inhibitor, a wavelength dispersion adjusting agent, an infrared absorber, a surfactant, and an antistatic agent. These additives may be solid or oily. That is, the melting point and boiling point are not particularly limited. For example, you may mix and use each ultraviolet absorber, a plasticizer, etc. of 20 degrees C or less and 20 degrees C or more. Such an example is described in Japanese Patent Application Laid-Open No. 2001-151901. Moreover, as an infrared absorber, what is described in Unexamined-Japanese-Patent No. 2001-194522 can be used, for example. In addition, preferable ones as additives are described in detail on pages 17 to 22 of the Japan Institute of Invention and Technology (Public Technical Number 2001-1745, published on March 15, 2001, Japan Society of Invention).

  The timing for adding each of these additives may be after the synthesis of cellulose acylate or before the synthesis is completed. Moreover, you may add in the pellet preparation process of a cellulose acylate, and also may add during the film formation process of a cellulose acylate.

The amount of each additive added is not particularly limited as long as the function is exhibited. Moreover, when the cellulose acylate film of this invention is formed from a multilayer, the kind and addition amount of the additive of each layer may differ. In the cellulose acylate film of the present invention, the total amount of each additive compound having a molecular weight of 200 or more is preferably 1 to 35% based on the weight of the cellulose acylate. More preferably, it is 1 to 25%, and further desirably 2 to 20%. As described above, these compounds include compounds that reduce optical anisotropy, wavelength dispersion adjusters, ultraviolet inhibitors, plasticizers, deterioration inhibitors, fine particles, release agents, infrared absorbers, and the like.
The molecular weight of these additives is preferably large in order to prevent thermal volatile evaporation from the viewpoint of thermal volatility and compatibility of cellulose acylate. On the other hand, if the molecular weight is too large, the compatibility with cellulose acylate is reduced, and the mobility in cellulose acylate is reduced. For this reason, molecular weight becomes like this. Preferably it is 200-3000, More preferably, it is 300-3000, Most preferably, it is 500-3000.

  If a plasticizer is added among the above additives, changes in Re and Rth of the cellulose acylate film accompanying a change in humidity can be effectively suppressed. Examples of the plasticizer include alkyl phthalyl alkyl glycolates, phosphoric acid esters and carboxylic acid esters. They may be solid or oily. That is, the melting point and boiling point are not particularly limited.

  Examples of alkyl phthalyl alkyl glycolates include methyl phthalyl methyl glycolate, ethyl phthalyl ethyl glycolate, propyl phthalyl propyl glycolate, butyl phthalyl butyl glycolate, octyl phthalyl octyl glycolate, methyl phthalyl ethyl glycol Rate, 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 phthalyl Chill glycolate, and the like.

  Examples of phosphate esters include triphenyl phosphate, tricresyl phosphate, biphenyl diphenyl phosphate, and the like. Furthermore, it is preferable to use the phosphate ester plasticizer described in claims 3 to 7 of JP-T-6-501040.

  Examples of carboxylic acid esters include phthalic acid esters such as dimethyl phthalate, diethyl phthalate, dibutyl phthalate, dioctyl phthalate and diethyl hexyl phthalate, and citrate esters such as acetyl trimethyl citrate, acetyl triethyl citrate and acetyl tributyl citrate. And adipic acid esters such as dimethyl adipate, dibutyl adipate, diisobutyl adipate, bis (2-ethylhexyl) adipate, diisodecyl adipate, and bis (butyl diglycol adipate). In addition, butyl oleate, methylacetyl ricinoleate, dibutyl sebacate, triacetin and the like are preferably used alone or in combination.

  When performing melt film formation, those having non-volatility can be particularly preferably used. For example, 1,4-phenylene-tetraphenyl phosphate, trinaphthyl phosphate, trisorthobiphenyl phosphate and the like described on pages 6 to 7 of JP-A-6-501040 can be used.

  These plasticizers are preferably used at 0% by mass to 10% by mass with respect to cellulose acylate, more preferably 1% by mass to 8% by mass, and further preferably 1% by mass to 6% by mass. These plasticizers may be used in combination of two or more as required.

  Of the above-mentioned additives, it is also preferable to add a deterioration preventing agent. By adding a phenol compound and adding a thioether compound or a phosphorus compound as necessary, a synergistic effect appears in preventing deterioration. As other deterioration inhibitors, materials described in detail on pages 17 to 22 of the Japan Society of Invention Public Technical Report (Public Technical Number 2001-1745, published on March 15, 2001, Japan Society of Invention) can be preferably used. .

  It is also preferable to add fine particles as a matting agent to the cellulose acylate film of the present invention. The fine particles used in the present invention include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, silica Mention may be made of magnesium and calcium phosphates. Fine particles containing silicon are preferable in terms of low turbidity, and silicon dioxide is particularly preferable. The fine particles of silicon dioxide preferably have a primary average particle size of 20 nm or less and an apparent specific gravity of 70 g / liter or more. A primary particle having an average diameter as small as 5 to 16 nm is more preferable because the haze of the film can be lowered. The apparent specific gravity is preferably 90 to 200 g / liter or more, and more preferably 100 to 200 g / liter or more. A larger apparent specific gravity is preferable because a high-concentration dispersion can be produced, and haze and aggregates are improved.

  These fine particles usually form secondary particles having an average particle size of 0.1 to 3.0 μm, and these fine particles exist in the film as aggregates of primary particles, and 0.1 to 0.1 μm on the film surface. An unevenness of 3.0 μm is formed. The secondary average particle size is preferably 0.2 μm to 1.5 μm, more preferably 0.4 μm to 1.2 μm, and most preferably 0.6 μm to 1.1 μm. For the primary and secondary particle sizes, the particles in the film were observed with a scanning electron microscope, and the diameter of a circle circumscribing the particles was defined as the particle size. In addition, 200 particles were observed at different locations, and the average value was taken as the average particle size.

  As fine particles of silicon dioxide, for example, commercially available products such as Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600 (above Nippon Aerosil Co., Ltd.) can be used. Zirconium oxide fine particles are commercially available, for example, under the trade names Aerosil R976 and R811 (manufactured by Nippon Aerosil Co., Ltd.), and can be used.

  Among these, Aerosil 200V and Aerosil R972V are fine particles of silicon dioxide having a primary average particle size of 20 nm or less and an apparent specific gravity of 70 g / liter or more, and the coefficient of friction is maintained while keeping the turbidity of the optical film low. It is particularly preferable because it has a great effect of reducing the effect.

<Cellulose acylate film>
Next, the cellulose acylate film of the present invention will be described. The cellulose acylate film of the present invention is produced by a melt film forming method or a solution film forming method described below.

(Melting film formation)
In the present invention, only one type of cellulose acylate may be used, or two or more types may be mixed. Moreover, polymer components other than the cellulose acylate of the present invention can be appropriately mixed. The polymer component to be mixed is preferably one having excellent compatibility with cellulose acylate, and the transmittance when formed into a film is preferably 80% or more, more preferably 90% or more, and particularly preferably 92% or more.

(Specific method of melt film formation)
Below, the specific method of melt film forming is demonstrated.
[1] Drying As a raw material for forming the cellulose acylate film of the present invention, it is preferable to use a material obtained by pelletizing cellulose acylate. That is, prior to melt film formation, the moisture content in the pellets is set to 1% or less, more preferably 0.5% or less, and then charged into a hopper of a melt extruder. At this time, the temperature of the hopper is preferably (Tg-50 ° C) to (Tg + 30 ° C) of cellulose acylate, more preferably (Tg-40 ° C) to (Tg + 10 ° C), and (Tg-30 ° C). ) To Tg is particularly preferable. Thereby, the re-adsorption of the water | moisture content in a hopper can be suppressed, and the said drying efficiency can be expressed more easily.

[2] Kneading extrusion Kneading and melting are preferably performed at 140 to 250 ° C, more preferably 150 to 240 ° C, and particularly preferably 160 to 235 ° C. At this time, the melting temperature may be a constant temperature, or may be divided into several parts and controlled. A preferable kneading time is 2 minutes to 60 minutes, more preferably 3 minutes to 40 minutes, and particularly preferably 3 minutes to 30 minutes. Furthermore, it is also preferable to carry out the inside of the melt extruder in an inert (nitrogen or the like) air stream or while evacuating using a vented extruder.

[3] Film formation The melted resin is passed through a gear pump, and after removing the pulsation of the extruder, it is filtered with a metal mesh filter or the like, and extruded from a T-shaped die attached behind it onto a cooling drum in the form of a sheet. Extrusion may be performed in a single layer, or multiple layers may be extruded using a multi-manifold die or a feed block die. At this time, the thickness unevenness in the width direction can be adjusted by adjusting the distance between the lips of the die.

  Thereafter, it is extruded onto a casting drum. At this time, it is preferable to use a method such as an electrostatic application method, an air knife method, an air chamber method, a vacuum nozzle method, or a touch roll method to increase the adhesion between the casting drum and the melt-extruded sheet. Such an adhesion improving method may be performed on the entire surface of the melt-extruded sheet or a part thereof.

In the present invention, it is more preferable to form a film using a touch roll on a casting drum after extrusion from a die after melting. In this method, the melt discharged from the die is sandwiched between a casting drum and a touch roll to be cooled and solidified. Such a touch roll preferably has elasticity in order to reduce residual strain generated when the melt from the die is sandwiched between the rolls. In order to give elasticity to the roll, it is necessary to make the outer cylinder thickness of the roll thinner than a normal roll, and the outer wall thickness Z is preferably 0.05 mm to 7.0 mm, more preferably It is 0.2 mm-5.0 mm, More preferably, it is 0.3 mm-2.0 mm or less. For example, by reducing the thickness of the outer cylinder, an elastic body layer is provided on a metal shaft or an elastic body layer, and the outer cylinder is placed on the elastic body layer, and a liquid medium layer is provided between the elastic body layer and the outer cylinder. The thing which enabled the touch roll film formation by the ultra-thin outer cylinder by satisfy | filling is mentioned. The casting roll and the touch roll preferably have a mirror surface, and the arithmetic average height Ra is 100 nm or less, preferably 50 nm or less, more preferably 25 nm or less. Specifically, for example, JP-A No. 11-314263, JP-A No. 2002-36332, JP-A No. 11-235747, WO 97/28950, JP-A No. 2004-216717, JP-A No. 2003-145609 are described. Can be used.
Thus, since the touch roll is filled with the fluid inside the thin outer cylinder, when the touch roll is brought into contact with the casting roll, it is elastically deformed into a concave shape by the pressing. Therefore, since the touch roll and the casting roll are in surface contact with the cooling roll, the pressure is dispersed and a low surface pressure can be achieved. For this reason, the fine unevenness | corrugation of the surface can be corrected, without leaving a residual distortion in the film pinched | interposed between these. The linear pressure of the preferred touch roll is 3 kg / cm to 100 kg / cm, more preferably 5 kg / cm to 80 kg / cm, and still more preferably 7 kg / cm to 60 kg / cm. The linear pressure referred to here is a value obtained by dividing the force applied to the touch roll by the width of the die outlet. By adjusting such a linear pressure, Rth can be adjusted (Rth is improved by increasing the linear pressure), and the Rth expression region can be further expanded. This promotes the surface orientation of the cellulose acylate film due to the surface pressure of the touch roll, and has the effect of increasing Rth. Further, since the surface pressure is uniformly applied as a whole, in-plane Re and Rth unevenness can be further reduced, and corner unevenness is more difficult to occur. Furthermore, the effect of further reducing fine unevenness (die line) and thickness unevenness formed on the film can be obtained by using Tachiroll.

The touch roll is preferably set to 60 ° C to 160 ° C, more preferably 70 ° C to 150 ° C, and still more preferably 80 ° C to 140 ° C. Such temperature control can be achieved by passing a temperature-controlled liquid or gas through these rolls.
The casting drum is preferably 60 ° C to 160 ° C, more preferably 70 ° C to 150 ° C, and particularly preferably 80 ° C to 150 ° C. Then, it peels off from a casting drum, winds up after passing through a nip roll. The winding speed is preferably 10 m / min to 100 m / min, more preferably 15 m / min to 80 m / min, and particularly preferably 20 m / min to 70 m / min.

The film forming width is preferably 1 m to 5 m, more preferably 1.2 m to 4 m, and particularly preferably 1.3 m to 3 m. The thickness of the unstretched film thus obtained is preferably 30 μm to 400 μm, more preferably 40 μm to 300 μm, and particularly preferably 50 μm to 200 μm. The thickness unevenness of the unstretched film is preferably 0% to 2% in both the thickness direction and the width direction, more preferably 0% to 1.5%, and still more preferably 0% to 1%.
The sheet thus obtained is preferably trimmed at both ends and wound up. The trimmed portion is recycled as a film raw material of the same type or as a film raw material of a different type after being pulverized or after being subjected to a granulation process or a depolymerization / repolymerization process as necessary. May be used. Moreover, it is also preferable from the viewpoint of scratch prevention to attach a laminate film on at least one side before winding.

(Solution casting)
Next, the preferable form of the solution-casting of the cellulose acylate of the present invention will be described.
In the present invention, the cellulose acylate solvent is not particularly limited as long as the object can be achieved within a range in which the cellulose acylate can be dissolved and cast and formed. Preferred solvents include chlorinated organic solvents such as dichloromethane, chloroform, 1,2-dichloroethane, tetrachloroethylene, and non-chlorinated organic solvents.
The non-chlorine organic solvent used in the present invention is preferably a solvent selected from esters, ketones and ethers having 3 to 12 carbon atoms. Esters, ketones and ethers may have a cyclic structure. A compound having two or more functional groups of esters, ketones and ethers (that is, —O—, —CO—, and —COO—) can also be used as a main solvent, such as an alcoholic hydroxyl group. It may have a functional group of 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 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.

  The non-chlorine organic solvent used 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 cast and formed into a film. These chlorinated organic solvents are preferably dichloromethane and chloroform. Particularly preferred is dichloromethane. In addition, there is no particular problem in mixing an organic solvent other than the chlorinated organic solvent. In that case, it is necessary to use at least 50% by mass of dichloromethane. The non-chlorine organic solvent used in combination with the present invention is described below. That is, as a preferable non-chlorine organic solvent, a solvent selected from esters, ketones, ethers, alcohols, hydrocarbons and the like having 3 to 12 carbon atoms is preferable. Esters, ketones, ethers and alcohols may have a cyclic structure. A compound having two or more functional groups of esters, ketones and ethers (that is, —O—, —CO— and —COO—) can also be used as a solvent. For example, other functional groups such as alcoholic hydroxyl groups can be used. You may have group simultaneously. In the case of a solvent having two or more types of functional groups, the number of carbon atoms may be within the specified range of the compound having any functional group. Examples of 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.

  The alcohol used in combination with the chlorinated organic solvent may be linear, branched or cyclic, and among them, saturated aliphatic hydrocarbon is preferable. 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, tert-butanol, 1-pentanol, 2-methyl-2-butanol and cyclohexanol. As the alcohol, fluorine-based alcohol is also used. Examples thereof include 2-fluoroethanol, 2,2,2-trifluoroethanol, 2,2,3,3-tetrafluoro-1-propanol and the like. Furthermore, the hydrocarbon may be linear, branched or cyclic. Either aromatic hydrocarbons or aliphatic hydrocarbons can be used. The aliphatic hydrocarbon may be saturated or unsaturated. Examples of hydrocarbons include cyclohexane, hexane, benzene, toluene and xylene.

  The chlorine-free organic solvent used in combination with the chlorine-based organic solvent that is the main solvent used in the cellulose acylate is not particularly limited, but methyl acetate, ethyl acetate, methyl formate, ethyl formate, acetone, dioxolane, dioxane , A ketone having 4 to 7 carbon atoms or an acetoacetate ester, an alcohol or hydrocarbon having 1 to 10 carbon atoms. Preferred non-chlorine organic solvents used in combination are methyl acetate, acetone, methyl formate, ethyl formate, methyl ethyl ketone, cyclopentanone, cyclohexanone, methyl acetyl acetate, methanol, ethanol, 1-propanol, 2-propanol, and 1-butanol. , 2-butanol, and cyclohexanol, cyclohexane, and hexane.

  The cellulose acylate of the present invention is preferably dissolved in an organic solvent in an amount of 10 to 35% by mass. More preferably, it is 13-30 mass%, and it is especially preferable that it is the cellulose acylate solution which melt | dissolved 15-28 mass%. The method for carrying out the cellulose acylate at these concentrations may be carried out so as to obtain a predetermined concentration at the stage of dissolution, or it is prepared as a low-concentration solution (for example, 9 to 14% by mass) and then concentrated as described later. You may adjust to a predetermined high concentration solution by a process. In addition, a cellulose acylate solution having a high concentration may be added to the cellulose acylate solution at a predetermined low concentration by adding various additives, and the cellulose acylate solution concentration of the present invention may be obtained by any method. There is no particular problem if it is implemented.

  Regarding the preparation of the cellulose acylate solution (dope) of the present invention, the dissolution method is not particularly limited, and it may be room temperature, or a cooling dissolution method or a high temperature dissolution method, or a combination thereof. With respect to these, for example, JP-A-5-163301, JP-A-61-106628, JP-A-58-127737, JP-A-9-95544, JP-A-10-95854, JP-A-10-45950, JP 2000-53784, JP 11-322946, JP 11-322947, JP 2-276830, JP 2000-273239, JP 11-71463, JP 04-259511, Special JP-A-2000-273184, JP-A-11-323017, JP-A-11-302388 and the like describe a method for preparing a cellulose acylate solution. The above-described method for dissolving cellulose acylate in an organic solvent is applicable to the present invention as long as it is within the scope of the present invention. The details of these methods, particularly for non-chlorine-based solvent systems, are described in detail on pages 22 to 25 of the Japan Institute of Invention Technology (Publication No. 2001-1745, published on March 15, 2001, Japan Society of Invention). Will be implemented. Further, the cellulose acylate dope solution of the present invention is usually subjected to solution concentration and filtration. Similarly, on the 25th page of the Japan Institute of Invention and Technology (Public Technical Number 2001-1745, published on March 15, 2001, Japan Society of Invention) It is described in detail. In addition, when it melt | dissolves at high temperature, it is the case where it is more than the boiling point of the organic solvent to be used, and in that case, it uses in a pressurized state.

  The cellulose acylate solution of the present invention preferably has a viscosity and dynamic storage modulus within the range. 1 mL of the sample solution was measured with a rheometer (CLS 500) using a Steel Cone having a diameter of 4 cm / 2 ° (both manufactured by TA Instruments). Measurement conditions were measured using an Oscillation Step / Temperature Ramp with a range of 40 ° C. to −10 ° C. being varied at 2 ° C./min, static non-Newtonian viscosity n * (Pa · s) at 40 ° C. and storage at −5 ° C. The elastic modulus G ′ (Pa) was determined. The measurement was started after the sample solution was kept warm at the measurement start temperature until the liquid temperature became constant. In the present invention, the viscosity at 40 ° C. is 1 to 400 Pa · s, the dynamic storage elastic modulus at 15 ° C. is preferably 500 Pa or more, more preferably the viscosity at 40 ° C. is 10 to 200 Pa · s, The dynamic storage elastic modulus at 15 ° C. is preferably 1 to 1,000,000. Furthermore, it is preferable that the dynamic storage elastic modulus at a low temperature is large. For example, when the casting support is −5 ° C., the dynamic storage elastic modulus is preferably 10,000 to 1,000,000 Pa at −5 ° C. When a body is -50 degreeC, it is preferable that the dynamic storage elastic modulus in -50 degreeC is 10,000-5 million Pa.

(Specific method of solution casting)
Next, the solution casting method will be specifically described. As a method and equipment for producing the cellulose acylate film of the present invention, a solution casting film forming method and a solution casting film forming apparatus conventionally used for producing a cellulose acylate film are used. The dope (cellulose acylate solution) prepared from the dissolving machine (kettle) is temporarily stored in a storage kettle, and the foam contained in the dope is defoamed for final preparation. The dope is fed from the dope discharge port to the pressure die through a pressure metering gear pump capable of delivering a constant amount of liquid with high accuracy, for example, by the number of rotations. The dry-dried dope film (also referred to as a web) is peeled off from the metal support at the peeling point which is uniformly cast on the metal support and the metal support has almost gone around. Both ends of the obtained web are sandwiched between clips, transported by a tenter while keeping the width, dried, then transported by a roll group of a drying device, dried, and wound up to a predetermined length by a winder. The combination of the tenter and the roll group dryer varies 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 device is added to the surface processing of the film. Each of these manufacturing processes is described in detail on pages 25 to 30 of the Japan Society of Invention Public Technical Report (Public Technical Number 2001-1745, published on March 15, 2001, Japan Society of Invention). Including), metal support, drying, peeling, stretching, etc.

  Here, although the space temperature of a casting part is not specifically limited in this invention, It is preferable that it is -50-50 degreeC. Furthermore, it is preferable that it is -30-40 degreeC, and it is especially preferable that it is -20-30 degreeC. In particular, the cellulose acylate solution cast at a low space temperature can be cooled on the support instantly to increase the gel strength, thereby holding the film containing the organic solvent. Thereby, without evaporating the organic solvent from the cellulose acylate, it can be peeled off from the support in a short time, and high-speed casting can be achieved. The means for cooling the space may be normal air, nitrogen, argon, helium or the like, and is not particularly limited. In that case, the relative humidity is preferably 0 to 70%, more preferably 0 to 50%. Moreover, in this invention, the temperature of the support body of the casting part which casts a cellulose acylate solution is -50-130 degreeC, Preferably it is -30-25 degreeC, Furthermore, it is -20-15 degreeC. In order to keep the casting part at the temperature of the present invention, it may be achieved by introducing a cooled gas into the casting part, or a cooling device may be arranged in the casting part to cool the space. At this time, it is important to take care not to attach water, and it can be carried out by a method such as using dry gas.

  In the present invention, the following configurations are particularly preferred for the contents and casting of each layer. That is, the cellulose acylate solution is a cellulose acylate solution containing 0.1 to 20% by mass of at least one liquid or solid plasticizer with respect to the cellulose acylate at 25 ° C. and / or Or a cellulose acylate solution containing 0.001 to 5% by mass of at least one liquid or solid UV absorber with respect to cellulose acylate, and / or the average particle of at least one solid It is a cellulose acylate solution containing 0.001 to 5% by mass of fine particle powder having a size of 5 to 3000 nm with respect to cellulose acylate, and / or at least one fluorine-based surfactant is cellulose. A cellulose acylate solution containing 0.001 to 2% by mass with respect to the acylate. And / or a cellulose acylate solution containing 0.0001 to 2% by mass of at least one release agent with respect to cellulose acylate, and / or at least one degradation inhibitor It is a cellulose acylate solution containing 0.0001 to 2% by mass with respect to acylate, and / or 0.1 to 15% by mass of at least one optical anisotropy control agent with respect to cellulose acylate. % And / or a cellulose acylate solution containing 0.1 to 5% by mass of at least one infrared absorber with respect to cellulose acylate.

In the casting step, one type of cellulose acylate solution may be cast in a single layer, or two or more types of cellulose acylate solutions may be cast simultaneously and / or sequentially. In the case of having a casting process comprising two or more layers, the composition of the chlorinated solvent in each layer is either the same or different in the cellulose acylate solution and the cellulose acylate film to be produced, each layer The additive is one type or a mixture of two or more types, the addition position of the additive to each layer is either the same layer or a different layer, The concentration in the solution is either the same or different in each layer, the aggregate molecular weight of each layer is either the same or a different aggregate molecular weight, Either the temperature is the same or a different temperature, the coating amount of each layer is the same or different, and the viscosity of each layer is the same Or whether the layer thickness after drying of each layer is the same or different, and the materials present in each layer are the same or different Or a distribution, a physical property of each layer being the same or a different physical property, and a physical property of each layer being either a uniform physical property or a different physical property distribution An acylate solution and a cellulose acylate film prepared from the solution are also preferable. Here, the physical properties include the physical properties described in detail on pages 6 to 7 of the Japan Society for Invention and Innovation Technical Report (Public Technical Number 2001-1745, published on March 15, 2001, Japan Society for Invention). For example, haze, transmittance, spectral characteristics, retardation Re, the same Rth, molecular orientation axis, axial misalignment, tear strength, folding strength, tensile strength, winding inner / outer Rt difference, creaking, dynamic friction, alkaline hydrolysis, curl value, water content Rate, residual solvent amount, heat shrinkage rate, high humidity dimensional evaluation, moisture permeability, base flatness, dimensional stability, heat shrinkage starting temperature, elastic modulus, and measurement of bright spot foreign matter, etc. Impedance and surface shape used for evaluation are also included. In addition, the Yellow Index, Transparency, Thermophysical Properties (Tg) of Cellulose Acylate described in detail on page 11 in the Japan Society for Invention and Innovation Technical Report (Public Technical Number 2001-1745, published on March 15, 2001, Invention Association) , Heat of crystallization) and the like.

  In the drying process, both ends of the web obtained by peeling are sandwiched between clips, transported by a tenter while holding the width, dried, then transported by a roll group of a drying apparatus, dried and finished with a winder. Take up to the length of. The combination of the tenter and the roll group dryer varies 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 device is added to the surface processing of the film.

The drying method in the solution casting in the present invention is not particularly limited. However, from the viewpoint of ensuring the photoelasticity of the film, a gradual temperature rising drying in which the temperature of the film is gradually increased from the state containing the solvent is more preferable. A retardation plate made of a cellulose acylate film as in the present invention is often used by being bonded to a polarizing layer in a liquid crystal display device. Many polarizing layers are obtained by impregnating PVA with iodine and uniaxially stretching. Since PVA is hydrophilic, it repeatedly expands and contracts with changes in humidity. For this reason, the cellulose acylate film bonded together with the polarizing layer is subjected to shrinkage and extension stress, and as a result, the orientation of the cellulose acylate molecule changes, and Re and Rth change. Such changes in Re and Rth associated with stress can be measured as photoelasticity, which is preferably 1 to 25 × 10 ⁻⁷ (cm ² / kgf), more preferably 1 to 20 × 10 ⁻⁷ (cm ² / kgf). ), More preferably 1 to 18 × 10 ⁻⁷ (cm ² / kgf).

  In the winding process, after the web is dried by the above-described method in the drying process, both ends are trimmed, and after embossing (knurling), the web is wound. The residual solvent in the film thus dried is preferably 0% by mass to 1% by mass, more preferably 0% by mass to 0.5% by mass. 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. Moreover, preferable winding length is 300m-30000m, More preferably, it is 500m-10000m, More preferably, it is 1000m-7000m. Moreover, it is also preferable from a viewpoint of scratch prevention to attach a lami film to at least one surface before winding.

  The film thickness after drying in this manner is preferably 30 to 200 μm, more preferably 35 μm to 180 μm, and particularly preferably 40 μm to 150 μm. The thickness unevenness of the unstretched raw fabric film is preferably 0% to 2% in both the thickness direction and the width direction, more preferably 0% to 1.5%, and still more preferably 0% to 1%.

<Extension>
As described above, the cellulose acylate film produced by melt film formation or solution film formation is stretched by 10% to 250% in at least one of the longitudinal direction and the transverse direction. Here, the vertical direction means the direction of film formation (longitudinal direction) of the cellulose acylate film, and the horizontal direction means a direction perpendicular to it.
By appropriately controlling the stretching conditions, the surface shape of the resulting cellulose acylate film is improved, Re and Rth are controlled within a desired range, and the residual stress in the width direction after winding the film is suppressed, It is possible to reduce dimensional changes and photoelasticity due to wet heat, and to suppress changes in optical characteristics (Re, Rth) with respect to stress. As a result, it is possible to effectively suppress the occurrence of frame unevenness when incorporated in a liquid crystal device. Specifically, the stretching is preferably performed under the preferable conditions described below. In particular, by controlling the amount of solvent remaining in the cellulose acylate film during stretching, the relaxation rate after stretching, and the cooling rate, the dimensional change and photoelasticity of the cellulose acylate film obtained after stretching are stabilized. And frame unevenness in the use environment can be effectively suppressed.

When producing the cellulose acylate film of the present invention, it is particularly preferable to dry-stretch the cellulose acylate film formed by solution casting or melt casting in a state where the residual solvent amount is 1% by mass or less. preferable.
Stretching may be performed on-line during the film forming process, or may be performed off-line after winding up once after film formation is completed. That is, in the case of melt film formation, the stretching may be performed at a stage where the cooling in the film forming process is not completed, or may be performed after the cooling is completed.
These stretching operations may be performed in one stage or in multiple stages. The stretching temperature is preferably Tg to (Tg + 40 ° C.), more preferably (Tg + 1 ° C.) to (Tg + 30 ° C.), and particularly preferably (Tg + 2 ° C.) to (Tg + 25 ° C.). A preferable draw ratio is 10% to 300%, more preferably 10% to 250%, and particularly preferably 20% to 200%. These stretching operations may be performed in one stage or in multiple stages. The draw ratio here refers to the final (substantially) draw ratio excluding the relaxation rate in the drawing direction. It is obtained using the following formula.

  Final stretch ratio (%) = 100 × {(substantially length after stretching) − (length before stretching)} / length before stretching

Stretching is performed by longitudinal stretching, lateral stretching, or a combination thereof. When performing longitudinal stretching, roll stretching (stretching in the longitudinal direction using two or more pairs of nip rolls with increased peripheral speed on the outlet side) or fixed end stretching (holding both ends of the film, and stretching it in the longitudinal direction) And the like which are gradually conveyed and stretched in the longitudinal direction) can be used. Further, when performing transverse stretching, tenter stretching (a film in which both ends of the film are gripped with a chuck and then stretched in the transverse direction (perpendicular to the longitudinal direction)) can be used. These longitudinal stretching and lateral stretching may be performed independently (uniaxial stretching) or may be performed in combination (biaxial stretching). In the case of biaxial stretching, it may be sequentially stretched in the longitudinal direction and the transverse direction (sequential stretching), or may be simultaneously stretched (simultaneous stretching).
In order to set the ratio of Re and Rth to a desired value, in the case of longitudinal stretching, the value obtained by dividing the space between nip rolls by the film width (aspect ratio) is controlled. That is, the Rth / Re ratio can be increased by reducing the aspect ratio. In the case of transverse stretching, it can be controlled by stretching in the orthogonal direction and simultaneously stretching in the longitudinal direction or conversely relaxing. That is, the Rth / Re ratio can be increased by stretching in the vertical direction, and the Rth / Re ratio can be decreased by relaxing in the vertical direction. Further, by combining longitudinal stretching and lateral stretching, Re and Rth are reduced by increasing Rth (increasing area magnification (longitudinal magnification x lateral magnification)) while reducing Re (making the longitudinal and lateral stretching ratios closer). Can be controlled. In the present invention, the difference in the draw ratio between the machine direction and the transverse direction is preferably 10% to 100%, more preferably 20% to 80%, and even more preferably 25% to 60%. Stretching is preferably performed in a longitudinal and lateral asymmetric manner. At this time, it is more preferable to increase the stretching ratio in the transverse direction.
The stretching speed of longitudinal stretching and lateral stretching is preferably 10% / min to 10000% / min, more preferably 20% / min to 1000% / min, particularly preferably 30% / min to 800% / min. In the case of multistage stretching, the average value of the stretching speed of each stage is indicated.

  After stretching, it is preferable to relax to some extent in the stretching direction. By performing relaxation, the dimensional stability of the stretched film can be improved, and the stress (stress) generated at the center and the edge during stretching can be eliminated, resulting in fluctuations in temperature and wet heat. Improvement of the dimensional stability of the film can be promoted, and frame unevenness in the use environment can be effectively suppressed. The relaxation is performed in the stretching direction at a ratio of 1% to 40%, more preferably 1% to 30%, and even more preferably 2% to 25% with respect to the stretching ratio (maximum stretching ratio) during stretching. To do.

  Subsequent to such stretching, it is also preferable to heat fix at a temperature of (Tg-30 ° C) to (Tg + 30 ° C) for 1 second to 3 minutes. It is more preferable to heat-set at a temperature of (Tg−20 ° C.) to (Tg + 20 ° C.) for 5 seconds to 2 minutes.

  The cellulose acylate film after being stretched and heat-fixed is preferably slowly cooled in a tensioned state. The slow cooling rate is preferably 1 ° C / min to 50 ° C / min, more preferably 2 ° C / min to 30 ° C / min, and even more preferably 3 ° C / min to 20 ° C / min.

It is preferable that Re and Rth of the cellulose acylate film of the present invention produced through the stretching as described above satisfy the following formula.
0 ≦ Re ≦ 300
10 ≦ Rth ≦ 500
1 ≦ Rth / Re ≦ 10
More preferably, 10 ≦ Re ≦ 200
50 ≦ Rth ≦ 400
1.1 ≦ Rth / Re ≦ 10
More preferably, 20 ≦ Re ≦ 150
80 ≦ Rth ≦ 350
1.2 ≦ Rth / Re ≦ 10

  In this specification, Re and Rth respectively represent in-plane retardation and retardation in the thickness direction at a wavelength λ. Re and Rth are measured at 25 ° C. and 60% relative humidity for 24 hours after humidity conditioning using an automatic birefringence meter (KOBRA-21ADH: manufactured by Oji Scientific Instruments) at 25 ° C. and 60% relative humidity. %. Re is measured by making light having a wavelength of λ nm incident in the normal direction of the film in KOBRA-21ADH (manufactured by Oji Scientific Instruments). Rth is Re, the slow axis in the plane (determined by KOBRA-21ADH) is used as the tilt axis (rotary axis), and the angle is changed with respect to the normal direction of the film, and light having a wavelength of λ nm is incident from the tilted direction. KOBRA-21ADH is calculated based on the plurality of retardation values measured. In this specification, 590 ± 5 nm is used as λ unless otherwise specified.

In the cellulose acylate film of the present invention, the difference between Re at 25 ° C. and relative humidity of 10% at a wavelength of 590 nm and Re at 25 ° C. and relative humidity of 80% is preferably 15 nm or less, and more preferably 10 nm or less.
The difference between Rth at 25 ° C. and relative humidity of 10% at a wavelength of 590 nm and Rth at 25 ° C. and relative humidity of 80% is preferably 25 nm or less, and more preferably 15 nm or less.

  The film thickness after stretching in this manner is preferably 10 to 200 μm, more preferably 20 μm to 200 μm, and particularly preferably 25 μm to 150 μm. The thickness unevenness is preferably 0% to 2% in both the thickness direction and the width direction, more preferably 0% to 1.5%, and still more preferably 0% to 1%.

The elastic modulus of the cellulose acylate film thus obtained is 1.5 kN / mm ² to
2.9 kN / mm ² is preferable, more preferably 1.7 kN / mm ^{2 to} 2.8 kN / mm ^2.
More preferably, it is 1.8 kN / mm ^{2 to} 2.6 kN / mm ² .

  The angle θ formed by the film forming direction (longitudinal direction) and the slow axis of Re of the film is preferably as close to 0 °, + 90 °, or −90 °. That is, in the case of longitudinal stretching, the closer to 0 °, the better, preferably 0 ± 3 °, more preferably 0 ± 2 °, and particularly preferably 0 ± 1 °. In the case of transverse stretching, 90 ± 3 ° or −90 ± 3 ° is preferable, 90 ± 2 ° or −90 ± 2 ° is more preferable, and 90 ± 1 ° or −90 ± 1 ° is particularly preferable.

  The cellulose acylate film of the present invention may be used alone, or may be used in combination with a polarizing plate, and a liquid crystal layer or a layer with a controlled refractive index (low reflection layer) or hard coat on these. A layer may be provided and used.

The cellulose acylate film of the present invention is preferably used as a polarizing plate protective film or a retardation plate. When used as a polarizing plate protective film or a retardation plate, the birefringence (Re, Rth) may change due to the stress due to expansion and contraction due to moisture absorption. The change in birefringence due to such stress can be measured as a photoelastic coefficient, and the range is preferably 1 to 25 × 10 ⁻⁷ (cm ² / kgf), and 1 to 20 × 10 ⁻⁷ (cm ² / kgf). kgf) is more preferable, and 1 to 18 × 10 ⁻⁷ (cm ² / kgf) is particularly preferable.

<Surface treatment>
The cellulose acylate film of the present invention produced by stretching may achieve improved adhesion between the cellulose acylate film and each functional layer (for example, an undercoat layer and a back layer) by optionally performing a surface treatment. Can do. For example, glow discharge treatment, ultraviolet irradiation treatment, corona treatment, flame treatment, acid or alkali treatment can be used. The glow discharge treatment here may be low-temperature plasma that occurs in a low-pressure gas of 10 ^{−3 to} 20 Torr, and plasma treatment under atmospheric pressure is also preferable. A plasma-excitable gas is a gas that is plasma-excited under the above-mentioned conditions, and examples thereof include chlorofluorocarbons such as argon, helium, neon, krypton, xenon, nitrogen, carbon dioxide, tetrafluoromethane, and mixtures thereof. It is done. Details of these are described in detail on pages 30 to 32 of the Japan Society of Invention Disclosure Technical Bulletin (Public Technical Number 2001-1745, published on March 15, 2001, Japan Society of Invention). Note that, in the plasma treatment at atmospheric pressure which has been attracting attention in recent years, for example, irradiation energy of 20 to 500 Kgy is used under 10 to 1000 Kev, and more preferably irradiation energy of 20 to 300 Kgy is used under 30 to 500 Kev. Among these, an alkali saponification treatment is particularly preferable, and it is extremely effective as a surface treatment of a cellulose acylate film.

  The alkali saponification treatment may be immersed in a saponification solution or coated with a saponification solution. In the case of the dipping method, it can be achieved by passing an aqueous solution of pH 10 to 14 such as NaOH or KOH through a bath heated to 20 ° C. to 80 ° C. for 0.1 to 10 minutes, and then neutralizing, washing with water and drying. .

  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 above solvent, and more preferably KOH or NaOH. The pH of the saponification coating solution is preferably 10 or more, more preferably 12 or more. The reaction conditions during the alkali saponification are preferably 1 second to 5 minutes at room temperature, more preferably 5 seconds to 5 minutes, and particularly 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 acid, and then with water. Further, 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 are described in JP 2002-82226 A and WO 02/46809 pamphlet.

It is also preferable to provide an undercoat layer for adhesion to the functional layer. This layer may be applied after the above surface treatment or may be applied without the surface treatment. The 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 Society of Invention).
These surface treatment and undercoating processes can be incorporated at the end of the film forming process, can be performed alone, or can be performed in the functional layer application process described later.

<Combination with functional layer>
The cellulose acylate film of the present invention is combined with the functional layer described in detail on pages 32 to 45 of the Japan Institute of Invention (Technical No. 2001-1745, published on March 15, 2001, Japan Institute of Invention). It is preferable. Among these, application of a polarizing film (formation of a polarizing plate), application of an optical compensation layer (optical compensation sheet), and application of an antireflection layer (antireflection film) are preferable.

[Polarizing film]
(Polarized film material)
Currently, a commercially available polarizing film is generally produced 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 film is manufactured by Optiva Inc. A coating type polarizing film typified by can also be used.
The iodine and the dichroic dye in the polarizing film develop polarizing 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 (for example, sulfo, amino, hydroxyl). For example, the compounds described in page 58 of the Japan Society of Invention Disclosure Technique (Public Technical No. 2001-1745, published on March 15, 2001, Japan Society of Invention).

  As the binder of the polarizing 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 binder include a methacrylate copolymer, a styrene copolymer, polyolefin, polyvinyl alcohol and modified polyvinyl alcohol, poly (N-methylolacrylamide) described in paragraph [0022] of JP-A-8-338913, Polyester, polyimide, vinyl acetate copolymer, carboxymethyl cellulose, polycarbonate and the like are included. Silane coupling agents can be used as the polymer.

Of these, water-soluble polymers (for example, poly (N-methylolacrylamide), carboxymethylcellulose, gelatin, polyvinyl alcohol, and modified polyvinyl alcohol) are preferable, gelatin, polyvinyl alcohol, and modified polyvinyl alcohol are more preferable, and polyvinyl alcohol and modified polyvinyl alcohol are preferable. Further preferred. 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%, 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, JP-A-9-152509 and JP-A-9-316127. Two or more kinds of polyvinyl alcohol and modified polyvinyl alcohol may be used in combination.
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. It is preferably not more than a commercially available polarizing plate (about 30 μm), more preferably 25 μm or less, and particularly preferably 20 μm or less.

  The binder of the polarizing film may be cross-linked. A polymer or monomer having a crosslinkable functional group may be mixed in the binder, or a crosslinkable functional group may be imparted to the binder polymer itself. Crosslinking can be performed by light, heat, or pH change, and a binder having a crosslinked structure can be formed. The crosslinking agent is described in US Reissue Patent 23297. Boron compounds (for example, boric acid and 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 wet heat resistance of the polarizing film 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 film)
The polarizing film is preferably dyed with iodine or a dichroic dye after the polarizing film is stretched (stretching method) or rubbed (rubbing method).
In the case of 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 by the 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 can be stretched more uniformly even at high magnification. More preferred is oblique stretching in which the film is stretched with an inclination of 10 to 80 degrees in the oblique direction.

(A) Parallel stretching method Prior to stretching, the PVA film is swollen. The degree of swelling is usually 1.2 to 2.0 times (mass ratio before swelling and after swelling). Thereafter, the film is stretched at a bath temperature of usually 15 to 50 ° C., preferably 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 performed by gripping with two pairs of nip rolls and increasing the conveyance speed of the subsequent nip rolls to be higher than that of the preceding nip rolls. The stretching ratio (after stretching / the length ratio in the initial state: the same hereinafter) is 1.2 to 3.5 times, more preferably 1.5 to 3.0 times from the viewpoint of the above-mentioned effects. Thereafter, the film is dried at 50 ° C. to 90 ° C. to obtain a polarizing film.

(B) Diagonal stretching method The oblique stretching method can be carried out by stretching using a tenter projecting in the tilting direction, as described in JP-A-2002-86554. 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, more preferably 50 ° C to 80 ° C. The relative humidity is preferably 50% to 100%, more preferably 70% to 100%, and particularly preferably 80% to 100%. The traveling speed in the longitudinal direction is preferably 1 m / min or more, 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., preferably 0.5 to 10 minutes, more preferably 1 to 5 minutes.
The absorption axis of the polarizing film thus obtained is preferably 10 ° to 80 °, more preferably 30 ° to 60 °, and particularly preferably 45 ° (40 ° to 50 °).

(Lamination)
The saponified cellulose acylate film and a polarizing film prepared by stretching are bonded to prepare a polarizing plate. The laminating direction is preferably such that the casting axis direction of the cellulose acylate film and the stretching axis direction of the polarizing plate are 45 °.
The bonding adhesive is not particularly limited, and examples thereof include PVA resins (including modified PVA such as acetoacetyl group, sulfonic acid group, carboxyl group, oxyalkylene group) and boron compound aqueous solution. preferable. 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 particularly preferably in the range of 40 to 50% in the light with 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 particularly 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 a circularly polarizing plate. In this case, lamination is performed so that the slow axis of the λ / 4 plate and the absorption axis of the polarizing plate are 45 degrees. At this time, the λ / 4 plate is not particularly limited, but more preferably has a wavelength dependency such that the retardation becomes smaller as the wavelength becomes lower. 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.

[Addition of optical compensation layer (creation of optical compensation sheet)]
The optically anisotropic layer is for compensating the liquid crystal compound in the liquid crystal cell in the black display of the liquid crystal display device, and forms an alignment film on the cellulose acylate film, and further provides an optically anisotropic layer. It is formed by doing.

(Alignment film)
An alignment film is 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 the alignment of the liquid crystalline compound, the alignment film plays the role and is not necessarily an essential component. That is, it is possible to produce a polarizing plate using the cellulose acylate film 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 (for example, ω-tricosanoic acid) formed 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 polymer rubbing treatment. 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 crosslinkability of bonding side chains having a crosslinkable functional group (for example, a double bond) to the main chain or aligning liquid crystalline molecules. It is preferable to introduce a 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 copolymers, styrene copolymers, polyolefins, polyvinyl alcohol and modified polyvinyl alcohol, poly (N-methylolacrylamide) described in paragraph No. [0022] of JP-A-8-338913, for example. ), Polyester, polyimide, vinyl acetate copolymer, carboxymethyl cellulose, polycarbonate and the like. Silane coupling agents can be used as the polymer. Water-soluble polymers (for example, poly (N-methylolacrylamide), carboxymethylcellulose, gelatin, polyvinyl alcohol, and modified polyvinyl alcohol) are preferable, gelatin, polyvinyl alcohol, and modified polyvinyl alcohol are more preferable, and polyvinyl alcohol and modified polyvinyl alcohol are particularly preferable. . 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%, more preferably 80 to 100%. It is preferable that the polymerization degree of polyvinyl alcohol is 100-5000.

  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 is 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 groups, dialkoxy groups, monoalkoxy groups), and the like. Specific examples of these modified polyvinyl alcohol compounds include those described in, for example, paragraph numbers [0022] to [0145] of JP-A No. 2000-155216 and paragraph numbers [0018] to [0022] of JP-A No. 2002-62426. Etc.

  When the side chain having a crosslinkable functional group is bonded to the main chain of the alignment film polymer or the crosslinkable functional group is introduced into the side chain having the function of aligning liquid crystal molecules, the alignment film polymer and optical anisotropy are obtained. The polyfunctional monomer contained in the 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] of JP-A No. 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] of JP-A No. 2002-62426. Aldehydes having high reaction activity, particularly glutaraldehyde are preferred.

  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 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 reticulation can be obtained. May occur.

  The alignment film can be basically formed by applying the polymer on the transparent support containing the alignment film forming material and the crosslinking agent, followed by drying by heating (crosslinking) and rubbing treatment. As described above, the crosslinking reaction may be performed at any time after coating 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 (for example, 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 alignment 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. A rod coating method is particularly preferable. The film thickness after drying is preferably 0.1 to 10 μm. Heat drying can be normally performed at 20 degreeC-110 degreeC. In order to form sufficient cross-linking, 60 ° C to 100 ° C is preferable, and 80 ° C to 100 ° C is more preferable. The drying time can usually be 1 minute to 36 hours, but is 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 usually 4.5 to 5.5, and 5 is particularly preferable.

The alignment film is provided on the transparent support or the undercoat layer. 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 step performed when manufacturing a liquid crystal display device can be applied. That is, a method of obtaining alignment by rubbing the surface of the alignment 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.

In industrial implementation, this is achieved by bringing the rotating rubbing roll into contact with the film with the polarizing film being transported. 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, 40 to 50 ° is preferable. 45 ° is particularly preferred.
The thickness of the alignment film thus obtained is preferably in the range of 0.1 to 10 μm.

(Optically anisotropic layer)
Next, the liquid crystalline molecules of the optically anisotropic layer are aligned on the alignment film. Thereafter, if necessary, the alignment film polymer is reacted with the polyfunctional monomer contained in the optically anisotropic layer, 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 low-molecular liquid crystals are cross-linked and no longer exhibit liquid crystallinity.

1) 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 crystalline 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 group described in paragraphs [0064] to [0086] of JP-A No. 2002-62427, A polymerizable liquid crystal compound is mentioned.

2) Discotic liquid crystalline molecules Discotic liquid crystalline molecules include 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 molecule or the assembly of molecules is preferably a compound having rotational symmetry and imparting 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 having a group that reacts with heat or light and, as a result, polymerized or cross-linked by reaction with heat or light, resulting in a high molecular weight and loss of 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. A compound in which the discotic core and the polymerizable group are bonded via a linking group is preferable, whereby the orientation state can be maintained even in the polymerization reaction. Examples thereof include compounds described in paragraph numbers [0151] to [0168] of 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 change in angle can be a continuous increase, a continuous decrease, an intermittent increase, an intermittent decrease, a change including a continuous increase and a continuous decrease, or an intermittent change including an increase and a decrease. The intermittent change includes a region where the inclination angle does not change in the middle of the thickness direction. Even if the angle includes a region where the angle does not change, the angle only needs to increase or decrease as a whole. Furthermore, it is preferable that the angle changes continuously.

  The average direction of the major axis of the discotic liquid crystalline molecules on the polarizing 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. In addition, the major axis (disk surface) direction of the surface-side (air-side) discotic liquid crystalline molecules is generally adjusted by selecting the type of additive used together with the discotic liquid crystalline molecules or discotic 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 major axis can also be adjusted by selecting liquid crystalline molecules and additives as described above.

(Other composition 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. It is preferable that the liquid crystal molecules have compatibility with the liquid crystal molecules and can change the tilt angle of the liquid crystal 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 the thing which shows copolymerizability with respect to the liquid crystal compound which has said polymeric group is preferable. Examples thereof include those described in paragraph numbers [0018] to [0020] of JP-A No. 2002-296423. The amount of the compound added is generally in the range of 1% by mass to 50% by mass and preferably in the range of 5% by mass 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 the compounds described in paragraph numbers [0028] to [0056] of JP-A No. 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.

A cellulose acylate can be mentioned as an example of a polymer. Preferable examples of cellulose acylate 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% by mass to 10% by mass with respect to the liquid crystalline molecule so as not to inhibit the alignment of the liquid crystal molecules. More preferably, it is in the range.
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 (for example, a wire bar coating method, an extrusion coating method, a direct gravure coating method, a reverse gravure coating method, or a 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 particularly preferably 1 to 10 μm.

(Fixing the alignment state of liquid crystalline molecules)
The aligned liquid crystal 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. A photopolymerization reaction is preferred.

  Examples of the photopolymerization initiator include α-carbonyl compounds (described in US Pat. Nos. 2,367,661 and 2,367,670), acyloin ether (US Pat. No. 2,448,828). Description), α-hydrocarbon substituted aromatic acyloin compounds (described in US Pat. No. 2,722,512), polynuclear quinone compounds (US Pat. Nos. 3,046,127 and 2,951,758). ), A combination of triarylimidazole dimer and p-aminophenyl ketone (described in US Pat. No. 3,549,367), acridine and phenazine compound (Japanese Patent Laid-Open No. 60-105667), U.S. Pat. No. 4,239,850) and oxadiazole compounds (described in 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 20~5000mJ / cm ^2, and particularly preferably in the range of 100 to 800 mJ / cm ² . 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.

(Combination with polarizing film)
It is also preferable to combine this optical compensation film and a polarizing film. Specifically, the optically anisotropic layer is formed by applying the coating liquid for the optically anisotropic layer as described above to the surface of the polarizing film. As a result, without using a polymer film between the polarizing film and the optically anisotropic layer, a thin polarizing plate with a small stress (strain × cross-sectional area × elastic modulus) associated with the dimensional change of the polarizing film is created. . When a polarizing plate using the 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 inclination angle of the polarizing film and the optical compensation layer is stretched so as to match the angle formed by the transmission axis of the two polarizing plates bonded to both sides of the liquid crystal cell constituting the liquid crystal display device and the vertical or horizontal direction of the liquid crystal cell. It is preferable. A normal inclination angle is 45 °. However, recently, transmissive, reflective, and transflective liquid crystal display devices have been developed that are not necessarily 45 °, and it is preferable that the stretching direction can be arbitrarily adjusted in accordance with the design of the liquid crystal display device.

<Liquid crystal display device>
Each liquid crystal mode in which such an optical compensation film is used will be described.
(TN mode liquid crystal display)
It is most frequently used as a color TFT liquid crystal display device and is described in many documents. The alignment state in the liquid crystal cell in the TN mode black display is an alignment state in which the rod-like liquid crystalline molecules rise at the center of the cell and the rod-like liquid crystalline molecules lie in the vicinity of the cell substrate.

(OCB mode liquid crystal display)
This is a bend alignment mode liquid crystal cell in which rod-like liquid crystal molecules are aligned in a substantially opposite direction (symmetrically) between the upper and lower portions of the liquid crystal cell. A liquid crystal display device using a bend alignment mode liquid crystal cell is 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. Therefore, 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 feature is that the rod-like liquid crystalline molecules are oriented substantially vertically when no voltage is applied. In the VA mode liquid crystal cell, (1) the rod-like liquid crystalline molecules are oriented substantially vertically when no voltage is applied. In addition to a narrowly defined VA mode liquid crystal cell (described in JP-A-2-176625) that is aligned substantially horizontally when a voltage is applied, (2) the VA mode is multi-domained to expand the viewing angle ( Liquid crystal cell (in MVA mode) (SID97, described in Digest of tech. Papers 28 (1997) 845), (3) A rod-like liquid crystal molecule is substantially vertically aligned when no voltage is applied, and twisted Liquid crystal cell in domain alignment mode (n-ASM mode) (described in the proceedings 58-59 (1998) of the Japanese Liquid Crystal Society) and (4) SURVAVAL mode liquid crystal cell (LCD interface) Presented at the National 98) are included.

(IPS mode liquid crystal display)
The feature is that the rod-like liquid crystalline molecules are aligned substantially horizontally in the plane when no voltage is applied, and this is characterized by switching by changing the orientation direction of the liquid crystal with or without voltage application. Specifically, as described in JP-A No. 2004-365941, JP-A No. 2004-12731, JP-A No. 2004-215620, JP-A No. 2002-221726, JP-A No. 2002-55341, and JP-A No. 2003-195333. Things 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.

<Application of antireflection layer (production of antireflection film)>
The antireflection film generally has 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 refractive index layer and a medium refractive index layer) on a transparent support. It is provided.
As a method of forming a multilayer film in which transparent thin films of inorganic compounds (metal oxides, etc.) having different refractive indexes are laminated, a chemical vapor deposition (CVD) method, a physical vapor deposition (PVD) method, or a sol-gel method of a metal compound such as a metal alkoxide. Examples thereof include a method of forming a thin film by forming a colloidal metal oxide particle film after post-treatment (ultraviolet irradiation: JP-A-9-157855, plasma treatment: JP-A-2002-327310).

On the other hand, various antireflection films in which thin films are laminated by applying a dispersion in which inorganic particles are dispersed in a matrix have been proposed as antireflection films having high productivity. Examples of the antireflection film by application include an antireflection film in which a layer provided with an antiglare property having fine irregularities on the surface is formed as the uppermost layer.
The cellulose acylate film of the present invention can be applied to the antireflection film produced by any of the above methods, but is particularly preferably applied to the antireflection film produced by a coating method (coating type).

(Layer structure of coating type antireflection film)
An antireflection film consisting of a layer structure in which at least a middle refractive index layer, a high refractive index layer, and a low refractive index layer (outermost layer) are sequentially formed on a transparent support is designed so that the refractive index satisfies the following relationship: The
The refractive index of the high refractive index layer> The refractive index of the medium refractive index layer> The refractive index of the transparent support> The refractive index of the low refractive index layer Further, a hard coat layer is provided between the transparent support and the medium refractive index layer. May be. Further, it may be composed of a medium refractive index hard coat layer, a high refractive index layer and a low refractive index layer. Examples thereof include those described in JP-A-8-122504, JP-A-8-110401, JP-A-10-300902, JP-A-2002-243906, JP-A-2000-11706, and the like.

Other functions may be imparted to each layer, for example, an antifouling low refractive index layer or an antistatic high refractive index layer (for example, JP-A-10-206603, JP-A-2002). -243906 etc.) etc. are mentioned.
The haze of the antireflection film is preferably 5% or less, and more preferably 3% or less. Further, the strength of the film is preferably H or more, more preferably 2H or more, and particularly 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 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 fine particles having a high refractive index include inorganic compounds having a refractive index of 1.65 or more, preferably inorganic compounds having a refractive index of 1.9 or more. Examples thereof 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 technique for treating the surface of the particles with a surface treatment agent (for example, described in JP-A Nos. 11-295503, 11-153703, and 2000-9908). A technique of treating with a silane coupling agent, a technique of treating with an anionic compound or an organometallic coupling agent described in JP-A-2001-310432, etc.), and a core-shell structure with high refractive index particles as a core. Technology (for example, technology described in JP 2001-166104 A), technology using a specific dispersant (for example, JP 11-153703 A, US Pat. No. 6,210,858 B1, JP Technology described in Japanese Patent Application Laid-Open No. 2002-27776069 and the like can be used. Examples of the material forming the matrix include conventionally known thermoplastic resins and curable resin films.

Further, the composition is selected from a composition containing a polyfunctional compound having at least two radically polymerizable and / or cationically polymerizable groups, an organometallic compound having a hydrolyzable group, and a composition of a partial condensate thereof. At least one composition is preferred. Examples of the compounds used in these compositions 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. For example, a curable film described in JP 2001-293818 A can be exemplified.

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 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 a layer formed by sequentially laminating on the high refractive index layer. The refractive index of the low refractive index layer is generally 1.20 to 1.55. Preferably it is 1.30-1.50.
The low refractive index layer is preferably constructed as an outermost layer having scratch resistance and antifouling properties. In order to greatly improve the scratch resistance, it is effective to impart slipperiness to the surface. Specifically, a conventionally known method for forming a thin film layer into which a silicone compound or a fluorine-containing compound is introduced can be applied. .

  The refractive index of the fluorine-containing compound is preferably 1.35 to 1.50. More preferably, it is 1.36-1.47. Moreover, it is preferable that a fluorine-containing compound is a compound containing the crosslinkable or polymerizable functional group which contains a fluorine atom in 35-80 mass%.

For example, paragraph numbers [0018] to [0026] of JP-A-9-222503, paragraph numbers [0019] to [0030] of JP-A-11-38202, and paragraph number [0027] of JP-A-2001-40284. To [0028], and compounds described in JP-A No. 2000-284102.
The silicone compound is a compound having a polysiloxane structure, and preferably has a curable functional group or a polymerizable functional group in the polymer chain and forms a crosslinked structure in the film. For example, reactive silicone (for example, Silaplane (manufactured by Chisso Corporation), polysiloxane having silanol groups at both ends (JP-A-11-258403, etc.) and the like can be mentioned.

The crosslinking or polymerization reaction of the fluorine-containing and / or siloxane polymer having a crosslinking or polymerizable group is carried out by light irradiation at the same time as or after coating the coating composition for forming the outermost layer containing a polymerization initiator or a sensitizer. It is preferable to carry out by heating.
A sol-gel cured film obtained by curing a condensation reaction between an organometallic compound such as a silane coupling agent and a silane coupling agent having a specific fluorine-containing hydrocarbon group in the presence of a catalyst is also preferable.

  For example, a polyfluoroalkyl group-containing silane compound or a partially hydrolyzed condensate thereof (Japanese Patent Laid-Open Nos. 58-142958, 58-147483, 58-147484, Japanese Patent Laid-Open Nos. 9-157582, 11) -106704), silyl compounds containing a poly (perfluoroalkyl ether) group which is a fluorine-containing long chain group (Japanese Patent Application Laid-Open Nos. 2000-117902, 2001-48590, 2002). And the like described in JP-A-53804).

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. A low refractive index inorganic compound, organic fine particles described in paragraphs [0020] to [0038] of JP-A-11-3820), silane coupling agents, slip agents, surfactants, and the like.
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 particularly preferably 60 to 120 nm.

(Hard coat layer)
The hard coat layer can be provided on the surface of the transparent support in order to impart physical strength to the antireflection film. In particular, it is preferably provided between the transparent support 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 is preferably a photopolymerizable functional group, and the organometallic compound having a hydrolyzable functional group 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 WO0 / 46617.
The high refractive index layer 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 in the description of the high refractive index layer.
The hard coat layer can also serve as an antiglare layer (described later) provided with particles having an average particle size of 0.2 to 10 μm to provide an antiglare function (antiglare 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 higher, more preferably 2H or higher, and particularly preferably 3H or higher, 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)
The forward scattering layer is provided in order to give a viewing angle improvement effect when the viewing angle is inclined in the vertical and horizontal directions when applied to a liquid crystal display device. By dispersing fine particles having different refractive indexes in the hard coat layer, it can also serve as a hard coat function.

  For example, Japanese Patent Application Laid-Open No. 11-38208 specifying a forward scattering coefficient, Japanese Patent Application Laid-Open No. 2000-199809 having a relative refractive index of a transparent resin and fine particles in a specific range, and Japanese Patent Application Laid-Open No. 2002 specifying a haze value of 40% or more. The technique described in -107512 gazette etc. can be used.

(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.

(Application 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 2000-281410 A, JP 2000-95893 A, JP 2001-100004 A, 2001-281407, etc.), an uppermost layer (antifouling layer) A method of physically transferring an 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) Wherein) and the like.

<Measurement method>
The measurement method used in the present invention is described below.

(1) Sampling 5 points in the width direction of the sample film (one center, two ends (5% of the total width from both ends), and two intermediate portions between the center and the end) 3 in every 10 m in the longitudinal direction The sample was sampled 15 times, and 15 sample pieces each having a size of 3 × 3 cm were taken out. The values of Re and Rth shown below are average values obtained by measuring 15 locations.

(2) Re and Rth
After the sample film was conditioned for 24 hours at 25 ° C. and 60% relative humidity, it was sampled at 25 ° C. and 60% relative humidity using an automatic birefringence meter (KOBRA-21ADH: manufactured by Oji Scientific Instruments). A retardation value at a wavelength of 590 nm was measured from a direction inclined in increments of 10 ° from + 50 ° to −50 ° from the normal to the film surface with the vertical direction and the slow axis as the rotation axis, and an in-plane retardation value ( Re) and the retardation value (Rth) in the film thickness direction were calculated. Re and Rth at 25 ° C. and 60% relative humidity are Re (60% RH) and Rth (60% RH), and Re and Rth refer to these values unless otherwise specified.

(3) Measurement of humidity fluctuation values of Re and Rth The humidity fluctuation values (ΔRe, ΔRth) of Re and Rth of each sample film were measured by the following method using the sample of (2) above.
After adjusting the humidity of the cellulose acylate film at 25 ° C. and 10% relative humidity for 24 hours or more, Re and Rth were calculated using an automatic birefringence meter (KOBRA-21ADH / PR: manufactured by Oji Scientific Instruments). These are designated as Re (10% RH) and Rth (10% RH). Next, after adjusting the same cellulose acylate film to 25 ° C. and 80% relative humidity for 24 hours or longer, using an automatic birefringence meter (KOBRA-21ADH / PR: manufactured by Oji Scientific Instruments), Re and Rth were Calculated. These are designated as Re (80% RH) and Rth (80% RH). Using these measured values and Re and Rth values of each cellulose acylate film [these correspond to Re (60% RH) and Rth (60% RH)], ΔRe and ΔRth were obtained according to the following formulas. The average of 15 measurement points was obtained and used as ΔRe and ΔRth of the cellulose acylate film.
ΔRe humidity fluctuation value (nm) = | Re (10% RH) −Re (80% RH) |
ΔRth humidity fluctuation value (nm) = | Rth (10% RH) −Rth (80% RH) |

(4) Coefficient of linear thermal expansion (CTE)
Sample pieces of 5 mm width × 20 mm length were collected in the casting direction (MD) and the transverse direction (TD) of the sample film. The linear thermal expansion coefficient is a constant tensile load method using TMA (Thermomechanical Analysis) (manufactured by Rigaku Denki Co., Ltd., TMA8310) in a nitrogen atmosphere of 100 ml / min in a range of 20 mN to 200 mN depending on the thickness of the film. Measurements were made at The measurement temperature was 20 ° C. to 140 ° C., and the temperature increase rate was 3 ° C./min. Linear thermal expansion coefficient (C
TE) was determined as an average expansion coefficient between 25 ° C. and 80 ° C. as shown in the following equation.
_{CTE = (L 80 -L 25)} / (L 25 × (T 80 -T 25)) (ppm / ℃)
(In the formula, L ₈₀ represents the length of the sample piece at 80 ° C., L ₂₅ represents the length of the sample piece at 25 ° C., T ₈₀ represents the measurement temperature of 80 ° C., and T ₂₅ represents the measurement temperature of 25 ° C.)

(5) Photoelastic coefficient (a) Two types of sample pieces having a width of 1 cm and a length of 10 cm were cut out so that the longitudinal direction of the sample was the MD direction and the TD direction, respectively.
(A) This is set in an ellipsometer (M-150 manufactured by JASCO), and a load of 100 g, 300 g, 500 g, 800 g, 1000 g, 1200 g, 1500 g, 1800 g, 2100 g is applied along the longitudinal direction (10 cm length). However, Re was sequentially measured with light of 632.8 nm at 25 ° C. and 60% relative humidity.
(C) Stress on the horizontal axis (value obtained by dividing the load by the film cross-sectional area (kgf / cm ² )), and Re on the vertical axis
The change (nm) is plotted, and the photoelasticity (cm ² ) in the MD direction and TD direction, respectively, from this slope
/ Kgf).

(6) Measurement of Tg in Dry State 10 mg of a sample film in a dry state (equilibrium water content is 1% or less) is sampled and placed in a DSC measurement pan. This was heated from 30 ° C. to 250 ° C. at 10 ° C./min in a nitrogen stream, and then cooled to 30 ° C. at −20 ° C./min. Thereafter, the temperature was raised again from 30 ° C. to 250 ° C. at a rate of 10 ° C./min, and the temperature at which the baseline began to deviate from the low temperature side was determined from the DSC curve and was defined as Tg in the dry state.
The aforementioned stretching temperature was set in a temperature range 1 to 30 ° C. higher than the dry Tg.

(7) Measurement of water-absorbed Tg 20 mg of a water-containing sample film immersed in pure water at 25 ° C. for 24 hours was placed in a DSC-measuring sealed pan (a completely sealed container for liquid-containing sample measurement). The measurement was performed by a first-run scan under the following conditions in a nitrogen stream in the Modulated DSC mode that can be detected with high accuracy. The temperature at which the 1st-run baseline begins to deviate from the low temperature side was defined as the Tg of water absorption.
DSC condition Container: Stainless steel sealing pan 70 μl
Measurement mode: Modulated DSC
Scanning temperature range: -50 to 200 ° C
Temperature increase rate: 2 ° C / min
Temperature drop rate: 20 ° C / min
Amplitude during temperature rise: ± 1 ° C
Amplitude period during temperature rise: 80 sec

(8) Dimensional change rate of film Three sample pieces each having a width of 50 mm and a length of 150 mm were collected from the casting direction (MD) and the transverse direction (TD) of the sample film. Holes of 6 mmφ were punched at 100 mm intervals on both ends of the sample piece. This was conditioned for 24 hours or more in a room at 25 ° C. and a relative humidity of 60%. Using an automatic pin gauge (manufactured by Shinto Kagaku Co., Ltd.), the original size (L1) of the punch interval was measured to a minimum scale of 1/1000 mm. Next, the sample piece was suspended in a thermostat at 60 ° C. and a relative humidity of 90% and heat-treated for 500 hours, and then the humidity was adjusted for 24 hours or more in a room at 25 ° C. and a relative humidity of 60%. The dimension (L2) of was measured. The wet heat dimensional change rate was calculated by the following equation. The dimensional change rate here is an average value of n = 3.
Dimensional change rate (%) = | (L1−L2) | / L1 × 100

(9) Residual solvent amount of membrane before stretching The amount of residual solvent of the membrane before stretching was determined by gas chromatography (GC-18A Shimadzu Corporation).
300 mg of the unstretched film was dissolved in 30 ml of a dissolving solvent (dissolved in methyl acetate when the solution was formed with a chlorinated solvent, dissolved in methyl acetate when dissolved with a non-chlorine solvent, or dissolved in dichloromethane when formed with a melt. Dissolved).
This was measured using gas chromatography (GC) under the following conditions, and quantified from the area of the peak other than the dissolved solvent using a calibration curve, and this sum was taken as the residual solvent amount.
Column: DB-WAX (0.25 mmφ × 30 m, film thickness 0.25 μm)
-Column temperature: 50 ° C
Carrier gas: Nitrogen Analysis time: 15 minutes Sample injection volume: 1 μl

(10) Equilibrium moisture content of film The sample film was allowed to stand for 24 hours under conditions of a temperature of 25 ° C and a relative humidity of 60%, and then the moisture content of the sample that reached equilibrium was measured by the Karl Fischer method. The obtained moisture content (g) was divided by the sample weight (g) to calculate the equilibrium moisture content. As a measuring device, a moisture measuring device CA-03 and a sample drying device VA-05 manufactured by Mitsubishi Chemical Corporation were used. As the Karl Fischer reagent, AKS and CKS manufactured by the same company were used.

(11) Evaluation of frame unevenness The polarizing plate on the observer side provided in the 22-inch and 26-inch liquid crystal display devices (manufactured by Sharp Corporation) using VA type liquid crystal cells is peeled off, and it becomes an evaluation object instead. The polarizing plate was affixed to the observer side via an adhesive so that the sample film was on the liquid crystal cell side. A liquid crystal display device was manufactured by arranging the transmission axis of the polarizing plate on the observer side and the transmission axis of the polarizing plate on the backlight side to be orthogonal to each other.
Further, a panel held at 60 ° C. and 90% relative humidity for 500 hours and a panel held at 25 ° C. and 60% relative humidity for 500 hours are arranged side by side and placed on the Schaukasten, and the corner portion of the VA liquid crystal device in the black display state The light leakage unevenness (frame unevenness) generated at the edge of the film was visually evaluated. Further, the ratio of the area of the frame generation (frame ratio) was obtained by the following formula.
Frame rate (%) = area of frame generation / total area of liquid crystal device × 100
The frame was evaluated in four ranks as follows.
◎ There was no light leakage unevenness at the edge of the corner of the liquid crystal device.
The frame rate was 0%, which was the highest image quality panel.
○ There was a slight light leak at the edges of the liquid crystal device.
The frame rate was 4% or less, and the panel had good image quality.
Δ: Light leakage was clearly observed at the edges of the four sides of the liquid crystal device.
The frame rate was 4% to 15%, and the product application was limited.
× Light leakage was observed entirely on the edges of the four sides of the liquid crystal device, and it occurred up to the center of the liquid crystal device.
The frame rate was 15% or more, which was an unfavorable level as a product.

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

<Synthesis Example 1> Synthesis of Cellulose Acetate Propionate 150 parts by mass of cellulose (hardwood pulp) and 75 parts by mass of acetic acid were placed in a reaction vessel equipped with a reflux apparatus and stirred at an internal temperature of 40 ° C for 2 hours. The cellulose subjected to such pretreatment was swollen and crushed to exhibit a fine powder-feather shape.

Separately, a mixture of 1545 parts by mass of propionic anhydride and 10.5 parts by mass of sulfuric acid was prepared as an acylating agent, cooled to −30 ° C., and then added to the reaction vessel containing the above-treated cellulose. . 0.5 hours after the addition of the acylating agent, the internal temperature was adjusted to 10 ° C., and 2 hours later, the internal temperature was adjusted to 23 ° C., and the internal temperature was maintained at 23 ° C. and further stirred for 3 hours. Thereafter, the internal temperature was cooled to 5 ° C, and 120 parts by mass of 25% by mass hydrous acetic acid cooled to 5 ° C was added over 1 hour. The internal temperature was raised to 40 ° C. and stirred for 1.5 hours. A mixed solution was prepared by adding an equal weight of water and an equal weight of acetic acid to magnesium acetate tetrahydrate equivalent to twice the molar amount of the sulfuric acid catalyst, added to the reaction vessel, and stirred for 30 minutes. 25 parts by mass of hydrous acetic acid 1000 parts by mass, 33% by mass hydrous acetic acid 500 parts by mass, 50% by mass hydrous acetic acid 1000 parts by mass and water 1000 parts by mass were added in this order to precipitate cellulose acetate propionate. The obtained cellulose acetate propionate was thoroughly washed with warm water. After washing, the mixture was stirred in a 0.005 mass% calcium hydroxide aqueous solution at 20 ° C. for 0.5 hour, further washed with water until the pH of the washing solution became 7, and then vacuum dried at 70 ° C.

According to ¹ H-NMR and GPC measurement, the obtained cellulose acetate propionate had an acetylation degree of 0.35, a propionylation degree of 2.55, and a polymerization degree of 190. The residual sulfuric acid content was 76 ppm, the magnesium content was 3 ppm, and the calcium content was 37 ppm. As a result of observing the film cast from the dichloromethane solution of this sample with a polarizing microscope, almost no insoluble matter was observed.

<Synthesis Example 2> Synthesis of Cellulose Acetate Butyrate 100 parts by mass of cellulose (hardwood pulp) and 135 parts by mass of acetic acid were placed in a reaction vessel equipped with a reflux apparatus and stirred at an internal temperature of 40 ° C for 2 hours. The cellulose subjected to such pretreatment was swollen and crushed to exhibit a fine powder-feather shape.

  Separately, a mixture of 1080 parts by weight of butyric anhydride and 10 parts by weight of sulfuric acid was prepared as an acylating agent, and after cooling to −20 ° C., it was added to a reaction vessel containing pretreated cellulose. After 30 minutes, the internal temperature was raised to 20 ° C. and reacted for 5 hours. Thereafter, the internal temperature was cooled to 5 ° C., and 2400 parts by mass of 12.5 mass% hydrous acetic acid cooled to about 5 ° C. was added over 1 hour. The internal temperature was raised to 30 ° C. and stirred for 1 hour. A mixed solution was prepared by adding an equal weight of water and an equal weight of acetic acid to magnesium acetate tetrahydrate equivalent to twice the molar amount of the sulfuric acid catalyst, added to the reaction vessel, and stirred for 30 minutes. 1000 parts by mass of acetic acid and 2500 parts by mass of 50% by mass hydrous acetic acid were gradually added to precipitate cellulose acetate butyrate. The obtained cellulose acetate butyrate precipitate was thoroughly washed with warm water. After washing, the mixture was stirred in a 0.005 mass% calcium hydroxide aqueous solution for 0.5 hour, further washed with water until the pH of the washing solution became 7, and then dried at 70 ° C. The obtained cellulose acetate butyrate had a degree of acetylation of 0.84, a degree of butyrylation of 2.02, and a degree of polymerization of 168. The residual sulfuric acid content was 92 ppm, the magnesium content was 2 ppm, and the calcium content was 50 ppm. As a result of observing the film cast from the dichloromethane solution of this sample with a polarizing microscope, almost no insoluble matter was observed.

<Manufacture example 1> Manufacture of a cellulose acylate film by solution casting (1) Preparation of cellulose acylate From the method of the above-mentioned cellulose acylate synthesis examples 1 and 2, composition of acylating agent, reaction temperature and time of acylation Various cellulose acylates described in Table 1 were synthesized in the same manner by changing the temperature and time of partial hydrolysis. Depending on the desired degree of acyl substitution, cellulose may be acylated (selected from acetic acid, acetic anhydride, propionic acid, propionic anhydride, butyric acid, butyric anhydride, alone or in combination), and as a catalyst Sulfuric acid was mixed and acylation was carried out while maintaining the reaction temperature at 40 ° C. or lower. After the cellulose as a raw material disappeared and acylation was completed, the heating was further continued at 40 ° C. or lower to adjust to a desired degree of polymerization. After adding an acetic acid aqueous solution to hydrolyze the remaining acid anhydride, partial hydrolysis was performed by heating at 60 ° C. or lower, and the desired total substitution degree was adjusted. The remaining sulfuric acid was neutralized with an excess amount of magnesium acetate. Reprecipitation was performed from an aqueous acetic acid solution, and further, washing with water was repeated to obtain cellulose acylates having different acyl group types, substitution degrees, and polymerization degrees shown in Table 1. The molecular weight distribution (Mw / Mn) of these cellulose acylates was 2.5 to 4.5. The degree of polymerization was precisely weighed about 0.2 g of completely dried cellulose acylate, dissolved in 100 ml of a mixed solvent of methylene chloride: ethanol = 9: 1 (mass ratio), and then dropped at 25 ° C. with an Ostwald viscometer. The number was measured and determined by the following formula.
ηrel = T / T0
[Η] = (1nηrel) / C
DP = [η] / Km
[Wherein T is the number of seconds that the sample is dropped, T0 is the number of seconds that the solvent is dropped, ln is the natural logarithm, C is the concentration (g / l), and Km is 6 × 10 ⁻⁴ ]

(2) Dissolution of cellulose acylate (preparation of dope)
1) Solvents Those listed in Table 1 were selected. The abbreviations indicate the following solvents.
“Non-chlorine” methyl acetate / acetone / methanol / ethanol / butanol (80/5/7/5/3: mass ratio)
“Chlorine-based” dichloromethane / methanol / butanol
(81.4 / 14.8 / 3.6: mass ratio)
“Chlorine-2” dichloromethane / butanol
(94/6: mass ratio)

2) Retardation increasing agent The retardation increasing agent described in Table 1 was selected. The abbreviations indicate the following compounds.

表１中の比較化合物は、特開２０００−３５２６２０号公報（特許文献２）記載の可塑剤１であり、構造式は下記のとおりである。

The comparative compound in Table 1 is the plasticizer 1 described in JP 2000-352620 A (Patent Document 2), and the structural formula is as follows.

3) Additives Further, the following additives were used. All the addition amounts (mass%) are the mass ratio with respect to 100 mass of cellulose acylates.
"Plasticizer A" Biphenyl diphenyl phosphate (1% by mass)
"UV agent a" 2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-tert-butylanilino) -1,3,5-triazine (0.2% 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 of about 7 (0.25 mass%)
"Citric acid ethyl ester" (monoester and diester mixed 1: 1, 0.2% by mass)
4) Swelling / Dissolution The above cellulose acylate, retardation increasing agent and additive were added to the solvent while stirring. When the addition was completed, stirring was stopped and the slurry was swelled at 25 ° C. for 3 hours to prepare a slurry. This was stirred again to completely dissolve the cellulose acylate.
5) Filtration / concentration Thereafter, the solution is filtered with a filter paper having absolute filtration accuracy of 0.01 mm (manufactured by Toyo Filter Paper Co., Ltd., # 63), and further filtered with a filter paper having absolute filtration accuracy of 2.5 μm (manufactured by Pall, FH025). did.

(3) Film formation The obtained dope was cast and formed using the method described in Table 1. The procedures of the solution band method and the solution drum method are as follows.
1) Band method It was cast on a mirror surface stainless steel support with a band length of 60 m set at 15 ° C through a Giesser. The Gieseer used was similar to that described in Japanese Patent Application Laid-Open No. 11-314233. The casting speed was 60 m / min and the casting width was 250 cm.
After peeling off in a state where the residual solvent amount is 100% by mass, the temperature was raised (excluded) between 40 ° C. and 110 ° C. at the rate shown in Table 1, then at 115 ° C. for 5 minutes and further at 120 ° C. for 20 minutes. After partial drying, a film-like cellulose triacylate film was obtained. After trimming both ends of the obtained film-like material 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 roll.
2) Drum method It was cast on a mirror surface stainless steel drum having a diameter of 3 m set at −15 ° C. through a Giesser. The Gieseer used was similar to that described in Japanese Patent Application Laid-Open No. 11-314233. The casting speed was 100 m / min and the casting width was 250 cm.
After peeling off the residual solvent at 200% by mass, the temperature was raised between 40 ° C. and 110 ° C. at the rate shown in Table 1 (removed temperature), and then dried at 115 ° C. for 5 minutes and further at 120 ° C. for 20 minutes. Thereafter, a film-like cellulose triacylate film was obtained. The obtained film-like material was trimmed at both ends by 3 cm, and then knurled with a height of 100 μm was applied to a portion 2 to 10 mm from both ends, and 2000 m was wound up in a roll shape.

Production Example 2 Production of Cellulose Acylate Film by Melt Film Formation (1) Preparation of Cellulose Acylate In the same manner as in Production Example 1, the amount of cellulose acylate required for evaluation was changed by changing the scale. Prepared.

(2) Pelletization of cellulose acylate The cellulose acylate was blown and dried at 120 ° C. for 3 hours to adjust the water content by the Karl Fischer method to 0.1 mass%. To this, the retardation increasing agent described in Table 1 was added, and further, 1% by mass of plasticizer (phenyldiphenyl phosphate) and 0.05% by mass of silicon dioxide particles (Aerosil R972V) were added to all levels, The mixture was kneaded in a hopper of a twin-screw kneading extruder. The biaxial kneading extruder was provided with a vacuum vent and evacuated (set to 0.3 atm).
After melting in this manner, it was extruded into a strand having a diameter of 3 mm in a water bath and immersed for 1 minute (strand solidification). The temperature was lowered by passing water at 10 ° C. for 30 seconds, and the product was cut to a length of 5 mm. The pellets thus prepared were dried at 100 ° C. for 10 minutes and then packaged.

(3) Melt Film Formation Cellulose acylate pellets prepared by the above method were dried with a vacuum dryer at 110 ° C. for 3 hours. This was put into a hopper adjusted to Tg-10 ° C., and cellulose acylate was melt-extruded using a single screw extruder under the screw conditions described below.
Screw compression ratio: 3
Screw L / D (length / diameter) ratio: 35 (exit side diameter 60 mm)
Screw temperature pattern: Upstream supply section (180-195 ° C)
Intermediate compression section (200-210 ° C)
Downstream metering section (220-235 ° C)
Rotation speed: 80 rpm (passing time 3 minutes)
Next, the melted cellulose acylate was passed through a gear pump to remove the pulsation of the extruder, followed by filtration with a metal 3 μm metal mesh filter. The filtered melt was cast onto a cast drum through a die lip set at 230 ° C. Three casting drums (CD) having a diameter of 60 cm set at Tg-5 ° C., Tg, and Tg-10 ° C. were continuously passed through and solidified to obtain a film-like cellulose acylate film. The distance from the tip of the die lip to the ground on the CD was set to 5 cm, and a 3 kV electrode was placed at a distance of 5 cm from the melt during this time, and both ends were subjected to electrostatic application treatment at 5 cm. . After trimming 5 cm at both ends, the both ends were subjected to thicknessing (knurling) with a width of 10 mm and a height of 50 μm. In each level, the width was 1.5 m, and 2000 m was wound at 30 m / min.

本発明の溶液流延または溶融流延製膜したＮｏ．１〜Ｎｏ．２０の膜状物の残存溶媒量および平衡含水量は前述のガスクロマトグラフィーおよびカールフィッシャー法にて測定したところ、全て溶媒残存率が０．５質量％以下であり、水分の含有量が１質量％以下であることを確認した。

The solution casting or melt casting film No. 1 of the present invention. 1-No. The residual solvent amount and the equilibrium water content of the film-like material of 20 were measured by the above-mentioned gas chromatography and Karl Fischer method. As a result, the residual solvent rate was 0.5% by mass or less and the water content was 1% by mass. % Or less was confirmed.

<Example 1> Production of cellulose acylate film (stretching)
After preheating the film-like cellulose acylate film obtained by solution casting or melt casting using several preheating rolls, using a nip roll and a clip transverse stretching tenter, the longitudinal direction described in Table 2 ( MD) and transverse direction (TD) stretch ratio. The stretching temperature was set to a temperature (Tg + 15 ° C.) 15 ° C. higher than the Tg of each level of resin (Tg in the dry state). The stretching speed was set to 600% / min in the longitudinal MD direction and 120% / min in the transverse TD direction. After stretching, while holding the film with a tenter clip, the film was relaxed at the relaxation rate described in Table 2 with respect to the maximum stretch ratio set in the transverse TD direction (the final stretch ratio described in Table 2 is the relaxation rate). The magnification was substantially stretched after the removal of. Thereafter, while maintaining the tension, the film was passed through a Tg-2 ° C. heat setting treatment zone, heat-fixed for 1 minute, and then slowly cooled to room temperature at a rate of 30 ° C./min via the cooling zone. Was wound up to obtain a stretched cellulose triacylate film.

(Evaluation of the physical properties)
Table 1 shows the physical properties of each cellulose acylate film obtained. In-plane retardation value Re and thickness direction retardation value Rth, Re and Rth humidity fluctuation value, Tg, absorbed Tg, linear thermal expansion coefficient, dimensional stability, based on the physical property measurement method described in this specification Photoelasticity and frame mounting evaluation were performed and are shown in Table 2. The obtained measurement results were comprehensively judged and evaluated according to three levels of criteria, and are shown in Table 2. “◯” is a level preferable for a product, “Δ” is a level where the use is limited, and “x” is a level not preferable for a product.

As can be seen from Tables 1 and 2, the No. of the present invention. 1-No. 13 and no. 17-No. The film No. 20 has a high Tg in a dry state and a Tg in a water absorption state, has a wide range of expression of Re and Rth, has little humidity fluctuation of ΔRe and ΔRth, and has a dimensional change rate, linear thermal expansion coefficient, light An optical film having all the elastic modulus within the range of the present invention and having little frame unevenness was obtained.
On the other hand, no. 14-No. No. 16 film is No. 1 of the present invention. 1-No. 13 and no. 17-No. Compared to film No. 20, the Tg in the dry state and the Tg in the water absorption state were low, the dimensional change rate, the linear thermal expansion coefficient, and the photoelastic coefficient were large, and the frame was clearly bad. Also, film No. containing no retardation increasing agent. 15-No. No. 16 of the present invention. 1-No. 13 and no. 17-No. As compared with the 20 film, it was found that the expression of Re and Rth is low, and it is difficult to satisfy the high Re value required for the VA liquid crystal cell. Furthermore, No. which did not carry out relaxation after stretching during the stretching process. No. 16 film has the same composition No. 16. Compared with 15 film, the dimensional change rate, linear thermal expansion coefficient, and photoelastic coefficient were large, and the frame unevenness tended to be further deteriorated.

Example 2 Application of Cellulose Acylate Film 1. Preparation of Polarizing Plate (1) Saponification of Cellulose Acylate Film A 2.5 mol / L sodium hydroxide aqueous solution as a saponification solution was adjusted to 60 ° C. The cellulose acylate film of the present invention was immersed for 2 minutes. Then, after being immersed in a 0.05 mol / L sulfuric acid aqueous solution for 30 seconds, it was passed through a water-washing bath.

(2) Production of Polarizing Film According to Example 1 of Japanese Patent Application Laid-Open No. 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 film having a thickness of 20 μm.

(3) Bonding The polarizing layer thus obtained, the saponified cellulose acylate film, and the saponified unstretched triacetate film (Fuji Photo Film Co., Ltd., Fujitac) were combined with PVA (Kuraray Co., Ltd.). The PVA-117H) 3% aqueous solution was used as an adhesive, and bonded in the following combinations so that the longitudinal direction of the polarizing axis and the cellulose acylate film was at an angle of 0 °, 45 °, or 90 °.
(I) Polarizing plate A type: Each stretched cellulose acylate No. 1-20 film / polarizing layer / unstretched cellulose acylate No. 1 in Table 1. 2 (ii) Polarizing plate B type: Each stretched cellulose acylate No. 1 in Table 2 1-20 film / polarizing layer / Fujitac

2. Creation of liquid crystal display element The polarizing plate on one side of the viewer provided on the 22-inch and 26-inch liquid crystal display devices (manufactured by Sharp Corporation) using VA type liquid crystal cells is peeled off, and the above-mentioned various polarizations are used instead. The plate A or B type was attached to the observer side via an adhesive so that the cellulose acylate film was on the liquid crystal cell side. A liquid crystal display device was prepared by arranging so that the transmission axis of the polarizing plate on the observer side and the transmission axis of the polarizing plate on the backlight side were orthogonal to each other.
The frame display unevenness of the obtained liquid crystal display device at 60 ° C. and 90% RH was evaluated by the method disclosed in the present invention. A panel that has been held at 60 ° C. and 90% relative humidity for 500 hours and a panel that has been held at 25 ° C. and 60% relative humidity for 500 hours are placed side by side on the Schacus Ten and generated at the corner of the VA liquid crystal device in the black display state. The light leakage (frame unevenness) and the frame area ratio were determined, and the results are shown in Table 2.
Visibility (change in color) of the obtained liquid crystal display device at 25 ° C. humidity change is a panel held for 2 weeks at a relative humidity of 10% at room temperature of 25 ° C. and a panel held at a relative humidity of 80% for 2 weeks. And the difference in color was visually evaluated. In the present invention, no. 1-No. 13 and no. 17-No. The liquid crystal display device using the 20 film was found to have a small change in color and high reliability. On the other hand, no. 14-No. The liquid crystal display device using the film No. 16 was a panel with inferior performance due to insufficient optical compensation of the liquid crystal cell or occurrence of uneven coloring.
In addition, according to Example 1 of Japanese Patent Application Laid-Open No. 2002-86554, a polarizing plate stretched using a tenter so that the stretching axis is inclined at 45 ° is similarly produced using the cellulose acylate film of the present invention. As with the above, good results were obtained.

3. 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-described saponified stretched cellulose acylate No. 1 of the present invention was used. 1-No. 13 and no. 17-No. 20 film was used, and this was attached to the bend-aligned liquid crystal cell described in Example 9 of JP-A-2002-62431 at 25 ° C. and 60% relative humidity, which was relative to 25 ° C. and 10% relative humidity. Brought into the humidity 80%. When the cellulose acylate film of the present invention was used, good display performance with a small change in contrast was obtained.

Furthermore, 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 produced by changing to the stretched cellulose acylate film of the present invention. In this case as well, a good optical compensation film could be produced.
Further, a polarizing plate and a retardation polarizing plate using the cellulose acylate film of the present invention are the liquid crystal display device described in Example 1 of JP-A No. 10-48420 and Example 1 of JP-A No. 9-26572. An optically anisotropic layer containing the discotic liquid crystal molecules described in 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, and JP-A-2000 When used in the 20-inch OCB type liquid crystal display device described in FIGS. 10 to 15 of JP-A-154261 and the IPS type liquid crystal display device shown in FIG. 11 of JP-A-2004-12731, a good liquid crystal display device is obtained. It was.

4). Production of Low Reflective Film A low reflective film was produced using the above-mentioned stretched cellulose acylate film according to Example 47 of the Japan Institute of Invention and Innovation (public technical number 2001-1745). As a result, the cellulose acylate film of the present invention was produced. Good optical performance was obtained when used.
Further, the low reflection film is formed by using a liquid crystal display device described in Example 1 of Japanese Patent Laid-Open No. 10-48420, a 20-inch VA liquid crystal display device described in FIGS. When a 20-inch OCB type liquid crystal display device described in FIGS. 10-15 of 2000-154261 was applied to the outermost layer of the liquid crystal display device, evaluation was made to obtain a good liquid crystal display device.

Example 3 Melt Film Formation by Touch Roll Method For No. 5, No. 10, and No. 17 to No. 20 of the present invention, the touch roll described in Example 1 of JP-A-11-235747 (double (Thin metal outer cylinder thickness was set to 3 mm) using touch rolls, and touch roll film formation was carried out under the conditions shown in Table 3 (except that touch roll film formation was performed) Implemented).
The planar shape (thickness unevenness and fine unevenness) of the unstretched cellulose acylate film thus obtained was measured and evaluated by the following method.

(Thickness unevenness measurement)
Sampling was performed at a width of 35 mm over the entire width of the cellulose acylate film (TD sample). The central part in the width direction was sampled 2 mm long with a width of 35 mm (MD sample). TD sample and MD sample were measured with a continuous thickness meter (FILM THICKNESS TESTER KG601A, manufactured by ANRITSU (Anritsu Electric Co., Ltd.)), and the average of (maximum value−average value) and (average value−minimum value) did.

(Fine unevenness (die line) measurement)
The cellulose acylate film was measured under the following conditions using a three-dimensional surface structure analysis microscope (New View 5022 manufactured by Zygo).
Objective lens: 2.5 times Image zoom: 1 time Measurement field of view: 2.8 mm in the width direction (TD), 2.1 mm in the longitudinal direction (MD)
Among them, the number of peaks (convex portions) having a height of 0.01 μm to 30 μm and valleys (concave portions) having a depth of 0.01 μm to 30 μm were counted. However, a convex part and a recessed part point out what is continuously 1 mm or more continuously in MD direction. The number of the convex portions and concave portions was divided by the measurement width (2.8 mm) and then multiplied by 100 to obtain the number of convex portions and concave portions per 10 cm. The above measurement was performed by measuring 30 points at equal intervals over the entire width of the formed sample film and averaging it, thereby obtaining the number of convex portions and concave portions per 10 cm width.

As shown in Table 3, it was confirmed that the fine unevenness (die line) and thickness unevenness formed on the film formed by melt film formation using the touch roll method were further improved. Moreover, it was confirmed that Rth of the film formed using the touch roll method is improved, and the optical property expression area is widened. Furthermore, it was confirmed by the frame mounting evaluation that the frame unevenness occurrence area ratio was reduced. Other physical properties of the unstretched and stretched cellulose acylate films showed characteristic values almost similar to those in Tables 1 and 2.
Furthermore, a touch roll similar to that of the first example of the pamphlet of WO 97/28950 (with a sheet forming roll) is used (however, the cooling water used for the metal outer cylinder starts at a temperature of 18 ° C. The oil was changed to 120 ° C.), and the touch roll was carried out under the conditions shown in Table 3, and the same results as in Table 3 were obtained.

  The cellulose acylate film of the present invention has a wide expression range of Re and Rth, which are optical characteristics, and can control the Re value and the Rth value within preferable ranges, respectively. For this reason, if this invention is used, according to liquid crystal modes, such as OCB and VA, Re value and Rth value are simultaneously controlled to a preferable range, and the film excellent in optical performance can be provided. The film can be used as a protective film and a retardation film for a polarizing plate, and can eliminate frame unevenness that occurs in the corner portion of the liquid crystal display device with changes in temperature and humidity. In addition to the high-quality retardation film and polarizing plate, an optical compensation film and an antireflection film can be provided using the cellulose acylate film of the present invention, and an image display device using these films can be provided. Can be provided. Therefore, the present invention is a useful invention with high industrial applicability.

It is the schematic which shows the one aspect | mode of the apparatus for performing the melt film formation by a touch roll method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Extruder 102 Gear pump 103 Filtration part 104 Die 105 Touch roll 106 Casting cooling drum 107 Cellulose acylate 108 Longitudinal stretch process part 109 Lateral stretch process part 110 Winding process part

Claims (15)

A cellulose acylate film obtained by stretching a cellulose acylate film formed by solution casting or melt casting in 10% to 250% in at least one of a longitudinal direction and a transverse direction,
The glass transition temperature in the dry state of the film is 100 ° C to 150 ° C, and
A cellulose acylate film having a glass transition temperature of 60 ° C to 110 ° C after the film is immersed in pure water at 25 ° C for 24 hours.   The cellulose acylate film according to claim 1, wherein the linear thermal expansion coefficient at 25 to 80 ° C is 5 to 150 ppm / ° C.   The absolute value of the dimensional change rate before and after leaving the film for 500 hours in an environment of 60 ° C. and 90% relative humidity is 0% to 0.5% in both the vertical and horizontal directions of the film, and the slow axis direction. 3. The cellulose acylate film according to claim 1, wherein the absolute value of the dimensional change rate is smaller than the absolute value of the dimensional change rate in the fast axis direction. The cellulose acylate film according to claim 1, which has a photoelastic coefficient of 1 × 10 ^{−7 to} 25 × 10 ⁻⁷ cm ² / kgf. The cellulose acylate according to any one of claims 1 to 4, wherein the cellulose acylate has two or more acylate groups having 2 to 6 carbon atoms and satisfies the following formulas (A) to (C). Rate film.
Formula (A): 2.5 ≦ X + Y ≦ 3.0
Formula (B): 0 ≦ X ≦ 2.5
Formula (C): 0.3 ≦ Y <3
(In the above formula, X represents the substitution degree of the acetyl group, and Y represents the total substitution degree of the acyl group having 3 to 6 carbon atoms.)   Containing at least one compound having two or more aromatic rings and a molecular weight of 200 to 3000 and a melting point of 50 ° C. to 250 ° C. in an amount of 0.1% by mass to 20% by mass with respect to cellulose acylate. The cellulose acylate film according to claim 1, wherein the cellulose acylate film is a film. The cellulose acylate film according to any one of claims 1 to 6, wherein the following formulas (1) to (3) are satisfied.
Formula (1): 0 ≦ Re ≦ 300
Formula (2): 10 ≦ Rth ≦ 500
Formula (3): 1 ≦ Rth / Re ≦ 10
(In the above formula, Re is the retardation in the film plane at a wavelength of 590 nm, and Rth is the retardation in the thickness direction of the film at a wavelength of 590 nm)   The difference between Re at 25 ° C./relative humidity 10% and Re at 25 ° C./relative humidity 80% is 15 nm or less, and the difference between Rth at 25 ° C./relative humidity 10% and Rth at 25 ° C./relative humidity 80% Is equal to or less than 25 nm (where Re is retardation in a film plane at a wavelength of 590 nm, and Rth is retardation in the thickness direction of the film at a wavelength of 590 nm). A cellulose acylate film according to claim 1.   The cellulose acylate film according to any one of claims 1 to 8, wherein the cellulose acylate film is melt-formed using a touch roll.   The cellulose acylate film-like product is stretched by 10% to 250% in at least one of the longitudinal direction and the transverse direction in a state where the residual solvent amount is 1% by mass or less, and is further 1% to the stretching ratio. The cellulose acylate film according to claim 1, wherein the cellulose acylate film is obtained by relaxing in the stretching direction at a ratio of 40%.   A polarizing plate using one or more cellulose acylate films according to claim 1.   A retardation film using one or more cellulose acylate films according to claim 1.   An optical compensation film using at least one cellulose acylate film according to claim 1.   The antireflection film which used one or more of the cellulose acylate films in any one of Claims 1-10.   The cellulose acylate film according to any one of claims 1 to 10, the polarizing plate according to claim 11, the retardation film according to claim 12, the optical compensation film according to claim 13, and the claim 14. An image display device formed using one or more films selected from the group consisting of antireflection films.

Images