CN1956835B - Cellulose acylate film and manufacturing method thereof - Google Patents

Abstract

The invention discloses a cellulose acylate film, which is characterized in that: the change rate (delta Re) of the in-plane retardation (Re) after aging at 80 ℃ for 1000 hours and the change rate (delta Rth) of the retardation (Rth) in the thickness direction after aging at 80 ℃ for 1000 hours are both 0 to 10%. The film is obtained by stretching the film lengthwise to 1.01 to 3 times under the condition that the aspect ratio (L/W) is more than 0.01 and less than 0.3. When the film is used as a retardation plate of a liquid crystal display device, color unevenness of the liquid crystal display device due to aging can be suppressed.

Description

Cellulose acylate film and manufacturing method thereof

technical field

The present invention relates to a good stretched cellulose acylate film which does not develop color unevenness with aging.

Background technique

Conventionally, a cellulose acylate film is used as a phase difference plate of a liquid crystal display device to expand the viewing angle. The cellulose acylate film is produced by stretching a cellulose acylate sheet to cause an in-plane retardation. (Re), retardation in the thickness direction (Rth).

As the stretching method of such a cellulose acylate sheet, there are known stretching methods in the longitudinal (length) direction (longitudinal stretching), stretching in the transverse (width) direction (transverse stretching), or both. A method of stretching in the longitudinal and transverse directions (simultaneous stretching). Among these stretching methods, since the equipment for longitudinal stretching is compact, it has been widely used until now.

As shown in Figure 1, the longitudinal stretching of the existing cellulose acylate sheet is usually carried out in the following manner: between two pairs or more than two pairs of nip rolls located on the inlet side and the outlet side respectively, the cellulose acylate The compound sheet 1 is heated to its glass transition temperature (Tg) or above, and the conveyance speed of the exit-side nip roller 3 is faster than that of the entrance-side nip roller 2 to adjust to an appropriate aspect ratio. In this specification, the so-called "aspect ratio" means: the distance (L) between the rotation center axis of the entrance side nip roll 2 and the rotation center axis of the exit side nip roll 3 divided by the cellulose acyl to be stretched. The value (L/W) obtained from the width (W) of the compound flake 1. When there are three or more pairs of nip rolls, the largest L/W is taken as the aspect ratio.

Several improvements have been proposed to this stretching method, for example, the following method has been proposed: by making the longitudinal stretching direction opposite to the cast film-making direction, thereby improving the angular inhomogeneity of the retarded phase axis (refer to Japanese Patent Application Laid-Open No. 2002-311240 Bulletin). In addition, a method of improving retardation (Rth) in the thickness direction by stretching at an aspect ratio (L/W) of 0.3 to 2 has also been proposed (see JP 2003-315551 A 2). However, when the stretched film obtained by these methods is used as a phase difference plate of a liquid crystal display device, there is a problem that color unevenness occurs on a liquid crystal display screen due to aging. Therefore, there is a need for this improvement.

Contents of the invention

The object of the present invention is to solve the above-mentioned problems. That is, the object is to provide a cellulose acylate film capable of suppressing color unevenness caused by aging of a liquid crystal display screen when used as a phase difference plate of a liquid crystal display device, and a method for producing the same.

The above objects of the present invention are achieved by the following configurations.

(1) A cellulose acylate film characterized in that the in-plane retardation (Re) is an aging change rate (δRe) at 80°C for 1000 hours, and the retardation in the thickness direction (Rth) is at 80°C. The aging change rate (δRth) of the next 1000 hours is 0% to 10%.

(2) The cellulose acylate film according to (1) above, wherein the in-plane retardation (Re) is 0 nm to 500 nm, and the thickness direction retardation (Rth) is 30 nm to 500 nm.

(3) The cellulose acylate film according to (1) or (2) above, wherein the surface waviness after aging has a height of 0 mm to 5 mm.

(4) A method for producing a cellulose acylate film, comprising a stretching step of longitudinally stretching a cellulose acylate sheet to 1.01 times to 2.5 times.

(5) The method for producing a cellulose acylate film according to (4) above, wherein in the stretching step, the cellulose acylate sheet is stretched to one time in the transverse direction by a tenter. ~2.5 times.

(6) The method for producing a cellulose acylate film according to the above (4) or (5), wherein the acyl group of the cellulose acylate sheet satisfies the following formula (1) and formula (2) Indicates the degree of substitution,

Formula (1): 2.5≤A+B<3.0

Formula (2): 1.25≤B<3.0

In the above formulas (1) and (2), A represents the degree of substitution of the acetyl group, and B represents the sum of the degrees of substitution of the propionyl, butyryl, pentanoyl and hexanoyl groups.

(7) The method for producing a cellulose acylate film according to any one of the above (4) to (6), wherein, in the stretching step, 1 to 10 preheating rolls Longitudinal stretching after passage.

(8) The method for producing a cellulose acylate film according to any one of (4) to (7) above, wherein in the stretching step, nip rolls with a diameter of 3 cm to 50 cm are used. The longitudinal stretching is performed.

(9) The method for producing a cellulose acylate film according to the above (7) or (8), wherein the preheating temperature of the preheating roll is (Tg-40° C.) to (Tg+60° C. ℃).

(10) A cellulose acylate film produced by the method for producing a cellulose acylate film according to any one of (4) to (9) above.

(11) A polarizing plate having at least one layer of polarizing film on the substrate, characterized in that the substrate is the cellulose acyl film described in any one of the above (1) to (3) or (10). compound film.

(12) An optical compensation film characterized in that the cellulose acylate film described in any one of (1) to (3) or (10) above is used as a substrate.

(13) An antireflection film characterized in that the cellulose acylate film described in any one of (1) to (3) or (10) above is used as a substrate.

According to the present invention, it is possible to provide a cellulose acylate film capable of suppressing color unevenness caused by aging of a liquid crystal display screen when used as a phase difference plate of a liquid crystal display device, and a method for producing the same.

Description of drawings

FIG. 1 is a schematic diagram for explaining aspect ratios in the present invention. In the figure, 1 is a cellulose acylate sheet, and 2 and 3 are nip rolls. The arrow shown at the top of Fig. 1 indicates the conveying direction.

Detailed ways

Next, the cellulose acylate film of the present invention and its production method will be described in detail. In this specification, "-" shows that the numerical value described before and after it is included as a lower limit and an upper limit. In addition, in the present invention, "Tg" represents the glass transition temperature of the cellulose acylate resin or film unless otherwise specified. In addition, in the present invention, "cellulose acylate sheet resin" means amorphous cellulose acylate before stretching, in the present invention, "cellulose acylate sheet" means cellulose acylate before stretching, " The "cellulose acylate film" means a stretched cellulose acylate comprising the cellulose acylate film of the present invention.

The inventors of the present invention investigated the cause of the color unevenness of the liquid crystal display screen caused by aging when the cellulose acylate film stretched from the cellulose acylate sheet was incorporated into the liquid crystal display device as a phase difference plate. analyze. As a result, it is known that the color unevenness is caused by the aging change rate (δRe, δRth) of the retardation (Re) in the plane of the cellulose acylate film due to stretching and the retardation (Rth) in the thickness direction (δRe, δRth) [hereinafter these are only referred to as "Re", "Rth", "δRe" and "δRth"].

In the cellulose acylate film of the present invention, δRe is 0% to 10%, more preferably 0% to 5%, and still more preferably 0% to 2%. In addition, in the cellulose acylate film of the present invention, δRth is 0% to 10%, more preferably 0% to 5%, and still more preferably 0% to 2%.

The aging change rates δRe and δRth of Re and Rth in the present invention are the change rates of Re and Rth after aging at 80° C. for 1000 hours, and are represented by the following formulas (3) and (4). In addition, aging at 80°C for 1000 hours is equivalent to aging at normal temperature for 10 years or more. This rate of aging change is more pronounced under dry heat conditions than under humid heat conditions.

Formula (3):

Re aging change rate (δRe: %) =

100×|Re(F)-Re(T)|/Re(F)

Formula (4):

Rth aging change rate (δRth: %) =

100×|Rth(F)-Rth(T)|/Rth(F)

In formula (3) and formula (4), Re(F) and Rth(F) respectively represent Re and Rth before aging for 1000 hours under the conditions of 80°C and relative humidity less than or equal to 10%, and Re(T) and Rth(T) respectively denote Re and Rth after aging for 1000 hours at 80°C and relative humidity less than or equal to 10%.

In addition, the in-plane retardation (Re) [nm] and thickness direction retardation (Rth) [nm] used in the present invention are represented by the following formulas (5) and (6).

Formula (5):

Re=|n(MD)-n(TD)|×T

Formula (6):

Rth=|{(n(MD)+n(TD))/2}-n(TH)|×T

In formulas (5) and (6), n(MD), n(TD) and n(TH) represent the refractive indices in the longitudinal direction, the width direction and the thickness direction, respectively, and T represents the film thickness in nm.

In the present invention, Re and Rth are generated by orienting molecules in the film by stretching. This stretching is performed by at least one of longitudinal stretching and transverse stretching. Preferably, the cellulose acylate sheet is stretched longitudinally to 1.01 to 3 times under the condition that the aspect ratio (L/W) is greater than 0.01 and less than 0.3, and then transversely stretched as necessary. Wherein, the longitudinal stretching can be implemented by changing the conveying speed between two or more pairs of nip rollers as used in the prior art. However, conventionally, it is implemented as follows, and the above-mentioned aspect ratio (L/W) is about 1 (0.7-1.5). This is because if the aspect ratio (L/W) exceeds this range, the device will become large, and if the aspect ratio (L/W) is less than the above range, it will be difficult to achieve high-magnification stretching due to severe stretching. On the other hand, in the manufacturing method of the cellulose acylate film of this invention, the cellulose acylate film of this invention can be obtained suitably by using an extremely small aspect ratio (L/W). In the production method of the present invention, the aspect ratio (L/W) is more than 0.01 and less than 0.3, preferably 0.03 to 0.25, more preferably 0.05 to 0.2. By stretching with an aspect ratio (L/W) in such a range, it is possible to perform intense stretching over a short distance, that is, for a short time, to orient the molecules. The inventors of the present invention discovered for the first time that the molecular orientation after such forcible orientation does not relax with aging, so that Re and Rth hardly change with aging, and developed the cellulose acylate film of the present invention.

In addition, the planarity of the cellulose acylate film after aging is also good after stretching and orientation is carried out so violently that the orientation is difficult to relax. The present inventors have found after research that if the planarity of the cellulose acylate film decreases, surface waviness (wrinkles when the film is placed on a flat surface becomes uneven) occurs, and the surface waviness becomes a color produced with aging. Main cause of inhomogeneity. That is, surface waviness occurs on the cellulose acylate film as it ages, indicating local dimensional changes. The cellulose acylate film of the present invention is usually used on a glass plate in a liquid crystal display device, so dimensional change is suppressed, and as a result, shrinkage and tensile stress are generated in the film. This stress causes Re and Rth to change with photoelasticity. As a result, local Re and Rth change, causing color non-uniformity in the liquid crystal display screen. In the present invention, such local changes in Re and Rth can be suppressed, and color unevenness in the liquid crystal display screen can be prevented.

In addition, the "waviness height" referred to in the present invention is: after aging for 1000 hours at 80°C, the sample film is unfolded on a horizontal and smooth workbench, and the height of the surface waviness generated at this time is fully measured. Measure and measure the maximum height (the maximum distance from the workbench to the film). This surface waviness is more pronounced under dry heating conditions than under humid heating conditions.

In the method for producing a cellulose acylate film of the present invention, strong orientation is formed by the above-mentioned intense stretching, thereby producing a cellulose acylate film of the present invention that is less prone to relaxation and dimensional change due to aging. As a result, changes in surface waviness are less likely to occur, and color unevenness of liquid crystal display screens due to aging is less likely to occur. In the present invention, the surface waviness height is preferably 0 mm to 5 mm, more preferably 0 mm to 4 mm, and even more preferably 0 mm to 3 mm.

Generally, if the stretching is performed vigorously as described above, it is easy to break and it is difficult to stretch at a high ratio, so it is difficult to achieve high Re and Rth. On the other hand, the inventors of the present invention found that by sufficiently preheating before stretching, it is possible to make it less likely to be broken. That is, according to the method for producing a cellulose acylate film of the present invention, in the stretching step, the cellulose acylate sheet is preferably 1 to 10, more preferably 2 to 8, and even more preferably The cellulose acylate film of the present invention can be obtained as a result of sufficient preheating by passing over 2 to 5 heat rolls.

On the other hand, if the cellulose acylate sheet is sufficiently preheated before stretching in this way, there is a tendency for the stretched nip rolls to easily adhere to the surface of the cellulose acylate sheet. As a countermeasure against such sticking, in the method for producing a cellulose acylate film of the present invention, it is preferable to use small-diameter nip rolls with a diameter of 3 cm to 50 cm, more preferably 5 cm to 40 cm, and still more preferably 7 cm to 35 cm. . That is, by using such a small roller, the contact angle between the film and the roller can be increased, and the contact area can be reduced. In addition, when the film is conveyed at the same speed, if a small-diameter roller is used, the rotation speed of the roller can be increased compared with a large-diameter roller, thereby shortening the contact time between the roller and the film. Due to these combined effects, sticking between the film and the roll can be suppressed.

In the cellulose acylate film production method of the present invention, utilize the preheating temperature of preheating roll preheating to be preferably (Tg-40 ℃)～(Tg+60 ℃), more preferably (Tg-20 ℃)～( Tg+40°C), more preferably (Tg) to (Tg+30°C). In addition, in the method for producing a cellulose acylate film of the present invention, the stretching temperature is preferably (Tg) to (Tg+60°C), more preferably (Tg+2°C) to (Tg+40°C), and even more preferably It is (Tg+5°C)～(Tg+30°C). In addition, in the production method of the present invention, the draw ratio is preferably 1.01 times to 3 times, more preferably 1.05 times to 2.5 times, and even more preferably 1.1 times to 2 times.

Such longitudinal stretching is preferably carried out in a state where the solvent remaining in the cellulose acylate sheet is 3% by mass or less, more preferably 2% by mass or less, and still more preferably 1% by mass or less. This is because: in the presence of residual solvents, the orientation of molecules in the film tends to relax with aging, and Re and Rth tend to change with aging.

In the method for producing a cellulose acylate film of the present invention, it is preferable to perform lateral stretching after the above-mentioned longitudinal stretching. Rth can be further increased by such stretching. Transverse stretching is preferably carried out using a tenter. The stretching temperature in the preferred transverse stretching is preferably (Tg) to (Tg+60°C), more preferably (Tg+2°C) to (Tg+40°C), and even more preferably (Tg+4°C) ~ (Tg+30°C). A preferred stretching ratio in transverse stretching is 1 to 2.5 times, more preferably 1.05 to 2.5 times, further preferably 1.1 to 2 times, and most preferably 1.1 to 2 times. It is preferable to relax the film in any one of the longitudinal direction and the transverse direction or in both directions of the longitudinal direction and the transverse direction after transverse stretching. Thereby, the distribution of retarded phase axes in the width direction can be reduced.

With such stretching, the cellulose acylate film of the present invention can be easily produced. Re of the cellulose acylate film of the present invention is preferably 0 nm to 500 nm, more preferably 10 nm to 400 nm, and still more preferably 15 nm to 300 nm. In addition, Rth of the cellulose acylate film of the present invention is preferably 30 nm to 500 nm, more preferably 50 nm to 400 nm, and most preferably 70 nm to 350 nm.

In the present invention, Re≦Rth is preferably satisfied, and Re×2≦Rth is more preferably satisfied. In order to achieve such a high Rth and low Re, it is preferable to stretch the cellulose acylate film longitudinally stretched as described above in the transverse (width) direction. That is, the difference in orientation between the longitudinal direction and the transverse direction becomes the difference in retardation (Re) in the plane, but since stretching is performed not only in the longitudinal direction but also in the transverse direction perpendicular to it, the difference between the orientations in the longitudinal direction and the transverse direction is reduced. Poor, the plane orientation (Re) can be reduced. On the other hand, since not only longitudinal stretching but also transverse stretching is performed to increase the area magnification, as the thickness decreases, the orientation in the thickness direction is strengthened and Rth can be increased.

In addition, the rate of change of both Re and Rth in the width direction and length direction (measurement location) is preferably 5% or less, more preferably 4% or less, and still more preferably 3% or less. These are achieved by stretching with a small aspect ratio (L/W) as described above. Specifically, it is because the stretching can be terminated before stretching unevenness is recognized on the film by performing vigorous stretching at a low aspect ratio (L/W).

Hereinafter, the cellulose acylate film of the present invention and its production method will be described in detail in order of implementation methods.

(Cellulose Acylate Resin)

The cellulose acylate resin used as a raw material for the cellulose acylate film of the present invention is not particularly limited as long as the cellulose acylate film satisfying the conditions of the present invention can be produced. It is preferable that the cellulose acylate resin is such that the acyl group of the formed cellulose acylate film satisfies the degree of substitution represented by the following formula (1) and the following formula (2). The "degree of substitution" in the present invention means the sum of the ratios of the hydrogen atoms of the hydroxyl groups at the 2-, 3-, and 6-positions of cellulose being substituted. When all the hydroxyl groups at the 2-position, 3-position and 6-position are substituted with acyl groups, the degree of substitution is 3.

Formula (1): 2.5≤A+B<3.0

Formula (2): 1.25≤B<3.0

(In the above formulas (1) and (2), A represents the degree of substitution of the acetyl group, and B represents the sum of the degrees of substitution of the propionyl group, butyryl group, pentanoyl group, and hexanoyl group).

Cellulose acylate resin, preferably,

· When 1/2 or more of B is a propionyl group, the above formula (1) and the above formula (2) are the following formula (1A) and the following formula (2A),

Formula (1A): 2.6≤A+B≤2.95

Formula (2A): 2.0≤B≤2.95

- When less than 1/2 of B is a propionyl group, the above formula (1) and the above formula (2) are the following formula (1A') and the following formula (2A').

Formula (1A'): 2.6≤A+B≤2.95

Formula (2A'): 1.3≤B≤2.5

More preferably,

· When 1/2 or more of B is a propionyl group, the above formula (1) and the above formula (2) are the following formula (1B) and the following formula (2B),

Formula (1B): 2.7≤A+B≤2.95

Formula (2B): 2.4≤B≤2.9

- When less than 1/2 of B is a propionyl group, the above formula (1) and the above formula (2) are the following formula (1B') and the following formula (2B').

Formula (1B'): 2.7≤A+B≤2.95

Formula (2B'): 1.3≤B≤2.0

In the present invention, it is preferable to decrease the degree of substitution of acetyl groups occupied in the acyl groups of the cellulose acylate resin, and to increase the sum of the degrees of substitution of propionyl, butyryl, pentanoyl, and hexanoyl groups. Thereby, the rate of change of Re and Rth accompanying aging after stretching can be reduced. This is because: by increasing the above-mentioned propionyl group longer than the acetyl group, etc., the flexibility of the film can be improved and the stretchability can be improved, so along with stretching, the orientation of the cellulose acylate molecules does not fluctuate, thus, The aging change rate of Re and Rth decreases. However, if the acyl group is longer than the above, it is not preferable because the glass transition temperature (Tg) or elastic modulus will be too low. For this reason, the acyl group of the above-mentioned cellulose acylate resin is preferably a propionyl group, a butyryl group, a valeryl group, or a hexanoyl group that is larger than an acetyl group, more preferably a propionyl group or a butyryl group, and even more preferably a butyryl group.

The basic principles of the synthesis methods of these cellulose acylate resins are described in Uda et al., Wood Chemistry, pages 180 to 190 (Kyoritsu publishing, 1968). A representative synthetic method is the liquid-phase esterification method with carboxylic anhydride-acetic acid-sulfuric acid catalyst. Specifically, the cellulose raw materials such as cotton linters and wood pulp are pretreated with an appropriate amount of acetic acid, and then put into the pre-cooled carboxylated mixture for esterification to synthesize complete cellulose acylate (2, The sum of the degrees of acyl substitution at the 3-position and 6-position is approximately 3.00). The above-mentioned carboxylated mixed solution generally contains acetic acid as a solvent, anhydrous carboxylic acid as an esterification agent, and sulfuric acid as a catalyst. Usually, the anhydrous carboxylic acid is used in a chemically excess amount with respect to the total amount of the cellulose reacted with it and the moisture present in the system. After the acylation reaction is completed, a neutralizing agent (such as calcium, magnesium, iron, aluminum or zinc carbonate, acetate or oxide) in water. Then, the obtained complete cellulose acylate is kept at 50-90° C. in the presence of a small amount of acetylation reaction catalyst (generally residual sulfuric acid), thereby saponifying and maturing it to change it to have the desired acyl group. Cellulose acylate with a degree of substitution and a degree of polymerization. When the desired cellulose acylate is obtained, the catalyst remaining in the system is completely neutralized with the above-mentioned neutralizing agent, or the cellulose acylate resin solution is put into water or dilute sulfuric acid without neutralization ( Or put water or dilute sulfuric acid into the cellulose acylate resin solution), separate the cellulose acylate resin, and obtain the cellulose acylate resin through cleaning and stabilization treatment.

The degree of polymerization of the cellulose acylate resin preferably used in the present invention has an average degree of polymerization of 200-700, preferably 250-550, more preferably 250-400, particularly preferably 250-350. In addition, the average degree of polymerization of the cellulose acylate resin preferably used in the present invention can be determined by the limiting viscosity method of Uda et al. (Uda Kazuo, Saito Hideo, Journal of Fiber Society, Vol. ) determination. In addition, it is described in detail in JP-A-9-95538.

Such adjustment of the degree of polymerization of the cellulose acylate resin can also be achieved by removing low molecular weight components. If low-molecular components are removed from cellulose acylate resin, the average molecular weight (polymerization degree) will increase, but the viscosity will be lower than that of ordinary cellulose acylate resin, so it is useful. The above-mentioned removal of low-molecular components can be carried out by washing the cellulose acylate resin with an appropriate organic solvent. In addition, the molecular weight of the cellulose acylate resin can also be adjusted by a polymerization method. For example, when producing cellulose acylate resin with few low-molecular components, it is preferable to adjust the amount of sulfuric acid catalyst in the acetylation reaction to 0.5 to 25 parts by mass relative to 100 parts by mass of cellulose. When the amount of the sulfuric acid catalyst is within the above-mentioned range, a cellulose acylate resin having an ideal molecular weight distribution (uniform molecular weight distribution) can be synthesized.

The cellulose acylate resin used in the present invention has a mass average molecular weight/number average molecular weight ratio (Mw/Mn ratio) measured by GPC, preferably 1.5 to 5.5, more preferably 2.0 to 5.0, further preferably 2.5 to 5.0, especially It is preferable to use a cellulose acylate resin having a Mw/Mn ratio of 3.0 to 5.0.

These cellulose acylate resins may be used alone or in combination of two or more. In addition, polymer components other than cellulose acylate may be appropriately mixed. The polymer component mixed in the cellulose acylate resin preferably has good compatibility with cellulose ester, and the transmittance at the time of film formation is preferably greater than or equal to 80%, more preferably greater than or equal to 90%, particularly preferably greater than or equal to 92%. %.

Furthermore, by adding a plasticizer to the cellulose acylate resin in the present invention, the rate of change of Re and Rth due to aging can be reduced. This is because the cellulose acylate resin is hydrophobized by adding the plasticizer, and relaxation of stretched orientation of the cellulose acylate molecules due to water absorption can be suppressed. Examples of plasticizers include alkylphthaloylalkylglycolic acid esters, phosphoric acid esters, and carboxylate esters.

Examples of alkyl phthaloyl alkyl glycolate include methyl phthaloyl methyl glycolate, ethyl phthaloyl ethyl glycolate, propyl phthaloyl propyl Glycolate, Butyl Phthalyl Butyl Glycolate, Octyl Phthalyl Octyl Glycolate, Methyl Phthalyl Ethyl Glycolate, Ethyl Phthalyl Methyl Glycolate, Ethylphthaloylpropylglycolate, Methylphthaloylbutylglycolate, Ethylphthaloylbutylglycolate, Butylphthaloylmethylglycolate, Butylphthaloyl Ethyl Glycolate, Propyl Phthalyl Butyl Glycolate, Butyl Phthalyl Propyl Glycolate, Methyl Phthalyl Octyl Glycolate, Ethyl Phthalyl Octyl Glycolate esters, octyl phthaloyl methyl glycolate and octyl phthaloyl ethyl glycolate, etc.

Examples of the phosphoric acid esters include triphenyl phosphate, tricresyl phosphate, diphenyl biphenyl phosphate, and the like. In addition, it is preferable to use the phosphate-based plasticizers described in claims 3 to 7 of JP-A-6-501040.

Examples of the above-mentioned carboxylic acid esters include dimethyl phthalate, diethyl phthalate, dibutyl phthalate, dioctyl phthalate, and diisooctyl phthalate. phthalates such as acetyl citrate, citrates such as acetyl trimethyl citrate, acetyl triethyl citrate and acetyl tributyl citrate, as well as dimethyl adipate, adipic acid Adipic acid such as dibutyl ester, diisobutyl adipate, bis(2-ethylhexyl) adipate, diisodecyl adipate and di(butyl diglycol adipate) ester. Furthermore, besides the above, butyl oleate, methyl acetyl ricinoleate, dibutyl sebacate, triacetylglycerol, and the like can also be used alone or in combination.

The amount of these plasticizers to be added is preferably 0 to 20% by mass, more preferably 1 to 20% by mass, and most preferably 2 to 15% by mass relative to the cellulose acylate resin. These plasticizers may be added in two or two types as needed. Use the above together.

In addition, in the above-mentioned cellulose acylate resin, in addition to plasticizers, various additives (such as UV inhibitors, antiaging agents, optical anisotropy control agents, fine particles, infrared absorbers, surfactants, or deodorizing agents) may be added. agent (amine, etc.) etc.). As the infrared absorbing dye, for example, those described in JP-A No. 2001-194522 can be used, and as the ultraviolet blocking agent, for example, those described in JP-A-2001-151901 can be used. The above-mentioned infrared absorber and the above-mentioned ultraviolet ray preventing agent are preferably contained in an amount of 0.001 to 5% by mass, respectively, based on the cellulose acylate resin. As the above-mentioned fine particles, those having a volume average particle size of 5 to 3000 nm are preferably used, and those made of metal oxides or cross-linked polymers may be used. The above-mentioned fine particles are preferably contained in an amount of 0.001 to 5% by mass based on the cellulose acylate resin. It is preferable to contain the said anti-aging agent in 0.0001-2 mass % with respect to cellulose acylate resin. As the optical anisotropy control agent, for example, those described in JP-A-2003-66230 and JP-A-2002-49128 can be used, and it is preferably contained in an amount of 0.1 to 15% by mass based on the cellulose acylate resin.

These cellulose acylate resins can be formed into sheets or films in both solution film forming and melt film forming.

(solution film formation)

As the solvent used for film formation from the solution of the cellulose acylate resin, any one of the following chlorine-based organic solvents and non-chlorine-based organic solvents can be used.

(1) Chlorinated organic solvents

The chlorinated organic solvent is preferably dichloromethane or chloroform. Dichloromethane is especially preferred. In addition, there is no particular problem in mixing organic solvents other than chlorine-based organic solvents. At this time, it is preferable to use at least 50 mass % or more of dichloromethane.

The chlorine-based organic solvent may also be used in combination with a non-chlorinated organic solvent. Next, a non-chlorinated organic solvent used in combination with the above-mentioned chlorinated organic solvent will be described. That is, the preferred non-chlorine organic solvent used in combination with the above-mentioned chlorine-based organic solvent is preferably a solvent selected from esters, ketones, ethers, alcohols, hydrocarbons, etc. having 3 to 12 carbon atoms. Esters, ketones, ethers and alcohols may have a cyclic structure. In addition, compounds having any one of two or more functional groups of esters, ketones, and ethers (i.e., -O-, -CO-, and -COO-) can also be used in combination with the chlorine-based organic solvents. For the use of the solvent, for example, other functional groups such as alcoholic hydroxyl groups may also be present at the same time. In the case of a solvent having two or more functional groups, the number of carbon atoms may be within the prescribed range for compounds having any one of the functional groups. Examples of esters having 3 to 12 carbon atoms include ethyl formate, propyl formate, amyl 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, cyclopentane, cyclohexanone, and methylcyclohexanone. Examples of ethers having 3 to 12 carbon atoms include: diisopropyl ether, dimethoxymethane, dimethoxyethane, 1,4-dioxirane, 1,3-dioxolane Cyclo, tetrahydrofuran, anisole and phenetole. Examples of organic solvents having two or more functional groups include 2-ethoxyethyl acetate, 2-methoxyethanol, and 2-butoxyethanol.

In addition, the alcohol used in combination with the chlorine-based organic solvent is preferably a straight chain, may have a branch, or may be cyclic, and among them, a saturated aliphatic hydrocarbon is preferable. The hydroxyl group of the alcohol may be any one of the first-order to third-order. Examples of the alcohol include: methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, t-butanol, 1-pentanol, 2-methyl-2-butanol, and cyclic Hexanol. In addition, a fluorine-based alcohol can also be used as the alcohol. Examples of the fluorine-based alcohol include 2-fluoroethanol, 2,2,2-trifluoroethanol, 2,2,3,3-tetrafluoro-1-propanol and the like. In addition, the hydrocarbon may be linear, branched, or cyclic. In addition, any of aromatic hydrocarbons and aliphatic hydrocarbons can be used as the solvent. The aliphatic hydrocarbon may be saturated or unsaturated. Examples of the hydrocarbon include: cyclohexane, hexane, benzene, toluene and xylene.

There are no special restrictions on the non-chlorinated organic solvents used in combination with chlorinated organic solvents, which can be selected from: methyl acetate, ethyl acetate, methyl formate, ethyl formate, acetone, dioxolane, and dioxirane , ketones or acetoacetates with 4 to 7 carbon atoms, alcohols or hydrocarbons with 1 to 10 carbon atoms. In addition, preferred non-chlorinated organic solvents used in combination include: methyl acetate, acetone, methyl formate, ethyl formate, methyl ethyl ketone, cyclopentane, cyclohexanone, methyl acetaldehyde acetate, methanol, Ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, and cyclohexanol, cyclohexane, hexane.

In the present invention, combinations of chlorine-based organic solvents that are preferable as main solvents are listed below, but are not limited thereto (numbers in parentheses below represent parts by mass).

Dichloromethane/Butanol (94/6)

Dichloromethane/Butanol/Methanol (84/4/12)

Dichloromethane/Methanol/Ethanol/Butanol (80/10/5/5)

Dichloromethane/Acetone/Methanol/Propanol (80/10/5/5)

Dichloromethane/Methanol/Butanol/Cyclohexane (80/10/5/5)

Dichloromethane/Methyl Ethyl Ketone/Methanol/Butanol (80/10/5/5)

Dichloromethane/Acetone/Methyl Ethyl Ketone/Ethanol/Isopropanol (72/9/9/4/6)

Dichloromethane/Cyclopentane/Methanol/Isopropanol (80/10/5/5)

Dichloromethane/Methyl Acetate/Butanol (80/10/10)

Dichloromethane/cyclohexanone/methanol/hexane (70/20/5/5)

Dichloromethane/Methyl Ethyl Ketone/Acetone/Methanol/Ethanol (50/20/20/5/5)

Dichloromethane/1,3 dioxolane/methanol/ethanol (70/20/5/5)

Dichloromethane/dioxirane/acetone/methanol/ethanol (60/20/10/5/5)

Dichloromethane/Acetone/Cyclopentane/Ethanol/Isobutanol/Cyclohexane (65/10/10/5/5/5)

Dichloromethane/Methyl Ethyl Ketone/Acetone/Methanol/Ethanol (70/10/10/5/5)

Dichloromethane/Acetone/Ethyl Acetate/Ethanol/Butanol/Hexane (65/10/10/5/5/5)

Dichloromethane/Methyl Acetoacetate/Methanol/Ethanol (65/20/10/5)

Dichloromethane/cyclopentane/ethanol/butanol (65/20/10/5)

(2) Non-chlorinated organic solvents

The non-chlorine organic solvent preferably used as the main solvent is preferably a solvent selected from esters, ketones, and ethers having 3 to 12 carbon atoms. Esters, ketones and ethers can also have a cyclic structure. Have any one compound in the functional group (that is, -O-, -CO- and -COO-) of two or more esters, ketones and ethers also can be used as main solvent, for example also can have alcoholic hydroxyl group Such other functional groups. In the case of a main solvent having two or more functional groups, the number of carbon atoms may be within the prescribed range for compounds having any one of the functional groups. Examples of esters having 3 to 12 carbon atoms include ethyl formate, propyl formate, amyl 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, cyclopentane, cyclohexanone, and methylcyclohexanone. Examples of ethers having 3 to 12 carbon atoms include: diisopropyl ether, dimethoxymethane, dimethoxyethane, 1,4-dioxirane, 1,3-dioxolane Cyclo, tetrahydrofuran, anisole and phenetole. Examples of organic solvents having two or more functional groups include 2-ethoxyethyl acetate, 2-methoxyethanol, and 2-butoxyethanol.

In addition, as the solvent for film formation of the cellulose acylate resin in the present invention, a mixed solvent can be preferably used. The mixed solvent is a mixed solvent of three or more different types, and the first solvent is selected from methyl acetate, ethyl acetate, methyl formate, ethyl formate, acetone, dioxolane and dioxirane At least one of or a mixture thereof, the second solvent is selected from ketones and acetoacetates with 4 to 7 carbon atoms, and the third solvent is selected from alcohols and hydrocarbons with 1 to 10 carbon atoms, preferably carbon Alcohols whose number is 1-8. In addition, in the case where the first solvent is a mixture of two or more solvents, the second solvent may not be present. The first solvent is more preferably methyl acetate, acetone, methyl formate, ethyl formate or mixtures thereof, and the second solvent is preferably methyl ethyl ketone, cyclopentane, cyclohexanone or methyl acetaldehyde glycolate. a mixture of these.

The alcohol as the third solvent may be linear, may have a branch, or may be cyclic, and is preferably a saturated aliphatic hydrocarbon. The hydroxyl group of the alcohol may be any of the first to third grades. Examples of the alcohol include: methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, t-butanol, 1-pentanol, 2-methyl-2-butanol, and cyclic Hexanol. In addition, a fluorine-based alcohol can also be used as the alcohol. Examples of the fluorine-based alcohol include 2-fluoroethanol, 2,2,2-trifluoroethanol, 2,2,3,3-tetrafluoro-1-propanol, and the like. In addition, the hydrocarbon may be linear, branched, or cyclic. Any of aromatic hydrocarbons and aliphatic hydrocarbons may be used as the hydrocarbon. Aliphatic hydrocarbons can be saturated or unsaturated. Examples of the hydrocarbon include cyclohexane, hexane, benzene, toluene and xylene. These alcohols and hydrocarbons as the third solvent may be used alone or in a mixture of two or more, and there is no special limitation. As the third solvent, preferred specific compounds can be listed: methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, cyclohexanol, cyclohexane and hexane, and preferably listed Methanol, ethanol, 1-propanol, 2-propanol and 1-butanol.

Among the above three mixed solvents, it is preferable to contain the first solvent at a rate of 20 mass % to 95 mass %, the second solvent at 2 mass % to 60 mass %, and the third solvent at a rate of 2 mass % to 30 mass %, more preferably It contains 30% to 90% by mass of the first solvent, 3% to 50% by mass of the second solvent, and 3% to 25% by mass of the third solvent. In addition, it is particularly preferable to contain the first solvent at 30% to 90% by mass, the second solvent at 3% to 30% by mass, and the third solvent to be alcohol at 3 to 15% by mass. In addition, when the first solvent is a mixed liquid without using the second solvent, it is preferable to contain the first solvent at a ratio of 20% to 90% by mass and the third solvent at a ratio of 5% to 30% by mass, and among them, preferably It contains 30 mass % - 86 mass % of a 1st solvent, and 7 mass % - 25 mass % of a 3rd solvent. The above-mentioned non-chlorinated organic solvents used in the present invention are described in detail on pages 12-16 of the Technical Bulletin of the Ming Association (public technology number 2001-1745, released on March 15, 2001, and the Ming Association).

Preferred combinations of non-chlorinated organic solvents in the present invention are listed below, but are not limited thereto (numbers in parentheses represent parts by mass).

Methyl acetate/acetone/methanol/ethanol/butanol (75/10/5/5/5)

Methyl acetate/acetone/methanol/ethanol/propanol (75/10/5/5/5)

Methyl acetate/acetone/methanol/butanol/cyclohexane (75/10/5/5/5)

Methyl acetate/acetone/ethanol/butanol (81/8/7/4)

Methyl acetate/acetone/ethanol/butanol (82/10/4/4)

Methyl acetate/acetone/ethanol/butanol (80/10/4/6)

Methyl acetate/methyl ethyl ketone/methanol/butanol (80/10/5/5)

Methyl Acetate/Acetone/Methyl Ethyl Ketone/Ethanol/Isopropanol (75/8/8/4/5)

Methyl acetate/cyclopentane/methanol/isopropanol (80/10/5/5)

Methyl acetate/acetone/butanol (85/10/5)

Methyl acetate/cyclopentane/acetone/methanol/butanol (60/15/15/5/5)

Methyl acetate/cyclohexanone/methanol/hexane (70/20/5/5)

Methyl acetate/methyl ethyl ketone/acetone/methanol/ethanol (50/20/20/5/5)

Methyl acetate/1,3 dioxolane/methanol/ethanol (70/20/5/5)

Methyl acetate/dioxirane/acetone/methanol/ethanol (60/20/10/5/5)

Methyl acetate/acetone/cyclopentane/ethanol/isobutanol/cyclohexane (65/10/10/5/5/5)

Methyl formate/methyl ethyl ketone/acetone/methanol/ethanol (50/20/20/5/5)

Methyl formate/Acetone/Ethyl acetate/Ethanol/Butanol/Hexane (65/10/10/5/5/5)

Acetone/Methyl Acetoacetate/Methanol/Ethanol (65/20/10/5)

Acetone/Cyclopentane/Ethanol/Butanol (65/20/10/5)

Acetone/1,3 dioxolane/ethanol/butanol (65/20/10/5)

1, 3 dioxolane/cyclohexanone/methyl ethyl ketone/methanol/butanol (60/20/10/5/5)

As described below, after the dissolution, it is preferable to add a part of the solvent to carry out the dissolution several times (numbers in parentheses represent parts by mass).

Prepare the cellulose acylate resin solution with methyl acetate/acetone/ethanol/butanol (81/8/7/4), add 2 parts by mass of butanol after filtration and concentration,

Prepare cellulose acylate resin solution with methyl acetate/acetone/ethanol/butanol (82/10/5/3), add 4 mass parts butanols after filtration, concentrating,

A cellulose acylate resin solution was prepared with methyl acetate/acetone/ethanol (84/10/6), and 5 parts by mass of butanol was additionally added after filtration and concentration.

In the present invention, in any case of a chlorinated organic solvent or a non-chlorinated organic solvent, it is preferable to dissolve 10% by mass to 40% by mass of the cellulose acylate resin in the solvent, more preferably 13% by mass. ~ 35% by mass, especially preferably 15% by mass to 30% by mass.

In addition, it is preferable to swell the cellulose acylate on conditions of 0° C. to 50° C. for 0.1 hour to 100 hours before dissolving.

In addition, various additives may be added before the swelling step, may be added during or after the swelling step, and may be added during or after cooling and dissolving thereafter.

In the present invention, in order to dissolve the cellulose acylate resin, cooling and heating methods can be used. The so-called cooling and heating methods can be used in Japanese Patent Application Laid-Open No. 11-323017, Japanese Patent Laid-Open No. 10-67860, Japanese Patent Laid-Open No. 10-95854, Japanese Patent Laid-Open No. 10-324774, Japanese Patent Laid-Open No. 11-302388 The methods described in the bulletin respectively. That is, what mixed and swelled the solvent and the cellulose acylate resin was dissolved using a screw-type kneader equipped with a cooling jacket.

In addition, in the present invention, it is preferable to implement concentration and filtration during doping, and these can be used in page 25 of the Technical Bulletin published by the Association for the Development of the Ming Dynasty (public technical number 2001-1745, published on March 15, 2001, and the Association for the Development of the Ming Dynasty). method in detail.

(melt film forming)

In the melt film forming, the cellulose acylate resin is dried, kneaded and extruded, and then cast into a film.

(1) dry

The cellulose acylate resin can be used as a powder as it is, but it is preferable to use a granulated resin in order to reduce thickness variation in film formation.

The cellulose acylate resin is preferably preliminarily made to have a water content of 1% or less, more preferably 0.5% or less, further preferably 0.1% 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, more preferably Tg-40°C to Tg+10°C, most preferably Tg-30°C to Tg. In this way, the re-adsorption of moisture in the hopper can be suppressed, and the above-mentioned drying efficiency can be more easily expressed. Furthermore, it is preferable to blow dehydrated air or an inert gas flow (nitrogen, etc.) into the hopper.

(2) Mixing and extrusion

The kneading and extrusion are performed preferably at 120°C to 250°C, more preferably at 140°C to 220°C, and even more preferably at 150°C to 200°C to melt the cellulose acylate resin. At this time, the melting temperature may be performed at a constant temperature, or may be controlled in several stages. The kneading time is preferably 2 minutes to 60 minutes, more preferably 3 minutes to 40 minutes, most preferably 4 minutes to 30 minutes. In addition, it is preferable to form an inert gas flow (nitrogen gas, etc.) in the melt extruder, or use an extruder with a vent hole, and carry out kneading and extrusion while vacuuming.

(3) Casting

The melted cellulose acylate resin is passed through a gear pump to eliminate the pulsation of the extruder, filtered with a metal mesh filter, etc., and extruded in a sheet form from a T-shaped die installed behind it onto a cooling drum. Extrusion can be performed in a single layer or in multiple layers using a multi-manifold or feed block die. At this time, by adjusting the gap between the cracks of the mold, the thickness unevenness in the width direction can be adjusted.

Thereafter the cellulose acylate resin is extruded onto a casting drum. At this time, it is preferable to use methods such as electrostatic application method, air knife method, air chamber method, vacuum nozzle method, touch roll method, etc. to improve the degree of adhesion between the casting drum and the melt-extruded sheet. This method of increasing the degree of adhesion may be performed on the entire melt-extruded sheet, or may be performed on a part (for example, only both ends).

The surface temperature of the casting drum is preferably 60-160°C, more preferably 70-150°C, most preferably 80-140°C. Thereafter, the flakes are peeled off from the casting drum, passed over nip rolls and taken up. The coiling speed is preferably 10 m/min to 100 m/min, more preferably 15 m/min to 80 m/min, most preferably 20 m/min to 70 m/min.

The film forming width is preferably 1 to 5 m, more preferably 1.2 to 4 m, and most preferably 1.3 to 3 m. The thickness of the unstretched film (sheet) thus obtained is preferably 30 to 400 μm, more preferably 40 to 300 μm, most preferably 50 to 200 μm.

It is preferable that the sheet obtained in this way is wound up after both ends are trimmed. The trimmed part can be reused as a raw material for the same type of film or a different type of film after crushing or, if necessary, granulation or depolymerization-repolymerization. In addition, from the viewpoint of preventing scratches, it is preferable to apply a bonding film on at least one side before winding up.

The glass transition temperature (Tg) of the solution-formed or melt-formed film of the cellulose acylate resin thus obtained is preferably 70°C to 180°C, more preferably 80°C to 160°C, and still more preferably 90°C to 150°C.

(Processing of cellulose acylate film)

After forming the film by the above method, in the stretching step, it is stretched monoaxially or biaxially by the above method to produce a stretched cellulose acylate film. The produced cellulose acylate film may be used alone or in combination with a polarizing plate, or may be used after providing a liquid crystal layer, a layer for controlling the refractive index (low reflection layer), or a hard coat layer thereon. These can be realized by the following steps.

(1) Surface treatment

The surface treatment of the cellulose acylate film can improve the degree of adhesion to each functional layer (such as an undercoat layer and a back layer). As the above-mentioned surface treatment, for example, glow discharge treatment, ultraviolet irradiation treatment, corona treatment, flame treatment, acid or alkali treatment can be used. The glow discharge treatment referred to here is a treatment in which plasma treatment is applied to the surface of the thin film in the presence of plasma excitation gas. The glow discharge treatment may be a low-temperature plasma treatment under a low-pressure gas of 10 ⁻³ to 20 Torr (0.13 to 2700 Pa), preferably a plasma treatment under an atmospheric pressure. Said above-mentioned plasma excitation gas refers to the gas which excites the plasma under the above-mentioned conditions, such as argon, helium, neon, krypton, xenon, nitrogen, carbon dioxide and tetrafluoromethane such fluorocarbon refrigerants and their mixtures etc. These are described in detail on pages 30 to 32 of the Invention Association's Public Technical Bulletin (public technical number 2001-1745, issued on March 15, 2001, Invention Association). In addition, plasma treatment under atmospheric pressure that has attracted attention in recent years uses, for example, irradiation energy of 20 to 500 KGy at 10 to 1000 KeV, preferably 20 to 300 KGy at 30 to 500 KeV.

Among these surface treatments, alkali saponification treatment is particularly preferred.

Alkaline saponification may be performed by immersing in a saponification solution (immersion method), or by applying a saponification solution (coating method). In the case of the dipping method, the cellulose acylate film is passed through an aqueous solution of pH 10 to 14 such as NaOH or KOH in a tank heated to 20°C to 80°C for 0.1 to 1 minute, then neutralized, washed with water, and dried. can be realised.

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 choice of the solvent of the alkali saponification treatment coating liquid is preferably in order to coat the transparent support of the saponification liquid and select a good wettability. In addition, the solvent of the saponification liquid will not form unevenness on the transparent support and maintain a good surface. state of the solvent. Specifically, ethanol-based solvents are preferred, and isopropanol is particularly preferred. In addition, 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 dissolved in the above-mentioned solvent, more preferably KOH and NaOH. The pH of the saponified coating solution is preferably 10 or more, more preferably 12 or more. The reaction conditions for alkali saponification are preferably room temperature for 1 second to 5 minutes, more preferably 5 seconds to 5 minutes, and most preferably 20 seconds to 3 minutes. Preferably, after the alkali saponification reaction, the surface to which the saponified liquid is applied is washed with water or acid, and then washed with water. In addition, coating-type saponification treatment and decoating of the alignment film described later can also be performed continuously, and the number of steps can be reduced. Specifically, these saponification methods include those described in JP-A-2002-82226 or WO02/46809.

In addition, it is preferable to provide an undercoat layer in order to adhere to the functional layer. This layer may be applied after the above-mentioned surface treatment, or may be applied without surface treatment. The details of the undercoat layer are described on page 32 of the Invention Association's Public Technical Bulletin (Technical No. 2001-1745, issued on March 15, 2001, Invention Association).

These surface treatment and undercoating steps may be carried out at the end of the film forming step, may be carried out alone, or may be carried out in the step of forming a functional layer described later.

(2) Forming a functional layer

In the cellulose acylate film of the present invention, it is preferable to incorporate the functional layer described in detail on pages 32 to 45 of the publication published by the Society of Inventions of the Invention (Technology No. 2001-1745, issued on March 15, 2001, the Society of the Invention of the Invention). Among them, formation of a polarizing film (polarizing plate), formation of an optical compensation layer (optical compensation sheet), and formation of an antireflection layer (antireflection film) are preferred.

(i) Formation of polarizing film (production of polarizing plate)

(イ—1) Raw materials used

Currently, commercially available polarizing films are generally produced by immersing a stretched polymer in a solution of iodine or a dichroic dye in a bath, and allowing the iodine or the dichroic dye to permeate into the adhesive. As the polarizing film, a coated polarizing film represented by Optiva Inc. can also be used. The iodine and dichroic dyes in the polarizing film produce orientation properties by aligning in the adhesive. As dichroic dyes, azo dyes, stilbene dyes, pyrazolone dyes, triphenylmethane dyes, quinoline dyes, oxazine dyes, thiazide dyes, or anthraquinone dyes can be used. The dichroic pigment is preferably water-soluble. The dichroic dye preferably has a hydrophilic substituent (for example, sulfo group, amino group, or hydroxyl group, etc.). For example, the compounds described on page 58 of the Public Technical Bulletin of the Association of Inventions of the Invention (Kokai No. 2001-1745, published on March 15, 2001).

As the adhesive for the polarizing film, a polymer that can be cross-linked by itself, a polymer that can be cross-linked with a cross-linking agent, or a combination of these can be used. Adhesives include, for example, methacrylate copolymers, styrene copolymers, polyolefins, polyvinyl alcohol and denatured polyvinyl alcohol, poly( N-methylolacrylamide), polyester, polyimide, vinyl acetate copolymer, carboxymethyl cellulose and polycarbonate, etc. In addition, a silane coupling agent can be used as a polymer. As the above-mentioned binder, water-soluble polymers (such as poly(N-methylolacrylamide), carboxymethylcellulose, keratin, polyvinyl alcohol and denatured polyvinyl alcohol) are preferable, and keratin, polyvinyl alcohol and denatured polyvinyl alcohol are more preferable. Denatured polyvinyl alcohol, most preferably polyvinyl alcohol and denatured polyvinyl alcohol. It is particularly preferable to use together two kinds of polyvinyl alcohols having different degrees of polymerization and denatured polyvinyl alcohols. The degree of saponification of polyvinyl alcohol is preferably 70 to 100%, more preferably 80 to 100%. It is preferable that the mass average degree of polymerization of polyvinyl alcohol is 100-5000. Denatured polyvinyl alcohol is described in JP-A-8-338913, JP-A-9-152509 and JP-A-9-316127, respectively. Polyvinyl alcohol and denatured polyvinyl alcohol can also be used in combination of two or more.

In the above polarizing film, the lower limit of the thickness of the adhesive 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 less than or equal to the thickness of a currently commercially available polarizing plate (about 30 μm), more preferably less than or equal to 25 μm, and most preferably less than or equal to 20 μm.

The adhesive of the polarizing film may also be crosslinked. Therefore, a polymer having a crosslinkable functional group and a monomer may be mixed in the adhesive, or the adhesive polymer itself may have a crosslinkable functional group. Crosslinking can be carried out by light, heat, or pH change, and an adhesive with a crosslinked structure can be formed. The crosslinking agent is described in US Reissued Patent No. 23297. In addition, a boron compound (for example, boric acid, borax) can also be used as a crosslinking agent. The amount of the crosslinking agent added to the adhesive is preferably 0.1 to 20% by mass based on the adhesive. The orientation of the polarizing element and the moisture resistance of the polarizing film are improved.

Preferably, after the crosslinking reaction is completed, the unreacted crosslinking agent is less than or equal to 1.0% by mass, more preferably less than or equal to 0.5% by mass. In this way, the anti-aging performance can be further improved.

(イ—2) Stretching of polarizing film

The polarizing film is preferably dyed with iodine or a dichroic dye after stretching the polarizing film (stretching method) or rubbing (rubbing method).

In the case of the stretching method, the stretching ratio is preferably 2.5 to 30.0 times, more preferably 3.0 to 10.0 times. Can be done by dry stretching in air. In addition, wet stretching in a state immersed in water may also be implemented. The draw ratio of dry stretching is preferably 2.5-5.0, and the draw ratio of wet stretching is preferably 3.0-10. Stretching may be performed parallel to the MD direction (parallel stretching) or may be performed in an oblique direction (diagonal stretching). These stretches can be done once or in multiples. Stretching uniformly can be performed even in the case of high-ratio stretching by dividing it into multiple times.

a) Parallel stretching method

The PVA film was swollen before stretching. The swelling degree is 1.2 to 2.0 times (weight ratio before swelling and after swelling). Thereafter, it is continuously conveyed by guide rollers, etc., and simultaneously stretched at a bath temperature of 15 to 50° C., more preferably at a temperature of 17 to 40° C. Stretch at bath temperature. Stretching is achieved by clamping with two pairs of nip rollers so that the conveying speed of the latter nip rollers is faster than that of the front nip rollers themselves. The stretch ratio is preferably 1.2 to 3.5 times, more preferably 1.5 to 3.0 times, based on the length ratio after stretching/initial state (the same applies hereinafter), and from the viewpoint of the effect of the above action. Thereafter, it is dried at 50 to 90° C. to obtain a polarizing film.

b) Oblique stretching method

As the diagonal stretching method, a method of stretching in a diagonal direction using a tenter extended in a diagonal direction described in JP-A-2002-86554 can be used. Since this stretching is performed in air, it is necessary to add water in advance to facilitate stretching. The preferred water content is 5 to 100%, more preferably 10 to 100%.

The temperature during stretching is preferably 40 to 90°C, more preferably 50 to 80°C. The relative humidity is preferably 50-100%, more preferably 70-100%, most preferably 80-100%. The advancing speed in the longitudinal direction is preferably greater than or equal to 1 m/minute, more preferably greater than or equal to 3 m/minute.

After completion of stretching, drying is preferably performed at 50 to 100°C, more preferably at 60 to 90°C for 0.5 minutes to 10 minutes. The drying time is more preferably 1 minute to 5 minutes.

The absorption axis of the polarizing film thus obtained is preferably 10 to 80 degrees, more preferably 30 to 60 degrees, and most preferably substantially 45 degrees (40 to 50 degrees).

(イ—3) Bonding

Preferably, the above saponified cellulose acylate film (substrate) and the stretched polarizing film are bonded together to produce a polarizing plate. The bonding direction is preferably performed so that the stretching direction of the polarizing plate is 45 degrees to the direction of the casting axis of the cellulose acylate film.

The adhesive used for bonding is not particularly limited, and PVA resins (modified PVA including acetoacetyl, sulfonic acid, carbonyl, and hydroxyalkylene, etc.) and boron compound aqueous solutions, etc., are listed, among which PVA resins are preferred. resin. The thickness of the adhesive layer is preferably 0.01-10 μm after drying, more preferably 0.05-5 μm.

The light transmittance of the polarizing plate thus obtained is preferably high, and the degree of polarization is also preferably high. The transmittance of the polarizing plate is preferably in the range of 30 to 50%, more preferably in the range of 35 to 50%, and most preferably in the range of 40 to 50% for light having a wavelength of 550 nm. The degree of polarization is preferably in the range of 90 to 100%, more preferably in the range of 95 to 100%, and most preferably in the range of 99 to 100% for light having a wavelength of 550 nm.

In addition, the polarizing plate thus obtained can be laminated with a λ/4 plate to produce circularly polarized light. In this case, the phase retardation axis of λ/4 and the absorption axis of the polarizing plate are laminated at 45 degrees. In this case, it is not particularly limited to λ/4, and it is more preferable to have a wavelength dependence in which the retardation value becomes smaller as the wavelength is lower. It is preferable to use a polarizing film having an absorption axis inclined at 20° to 70° relative to the longitudinal direction, and a λ/4 plate composed of an optically anisotropic layer made of a liquid crystal compound.

(O) Formation of optical compensation layer (manufacture of optical compensation sheet for liquid crystal display device)

The optically anisotropic layer is used to compensate the liquid crystal compound in the liquid crystal cell in the black display of the liquid crystal display device, and is formed by forming an alignment film on a cellulose acylate film, and then forming an optically anisotropic layer.

(O-1) Alignment film

An orientation film is preferably provided on the above-mentioned surface-treated cellulose acylate film. This film has the function of regulating the alignment direction of liquid crystal molecules. However, since the liquid crystalline compound functions as an alignment film as long as its alignment state is fixed after alignment, it is not necessarily a constituent element of the present invention. That is, it is also possible to transfer only the optically anisotropic layer on the alignment film whose orientation state is fixed to a polarizing element to manufacture a polarizing plate using the cellulose acylate film of the present invention as a base material.

The alignment film can be treated by rubbing of organic compounds (preferably polymers), oblique direction evaporation of inorganic compounds, formation of a layer with dense texture, or organic compounds (such as ω-di tridecyl ammonium chloride, dioctadecylmethylammonium chloride and methyl stearate) to set the accumulation method. In addition, it is known that the application of an electric field, application of a magnetic field, or irradiation of light produces an alignment film having an alignment function.

The alignment film is preferably formed by rubbing treatment of a polymer. In principle, the polymer used in the alignment film has a molecular structure that functions to align liquid crystalline molecules.

In the present invention, in addition to the function of aligning liquid crystalline molecules, it is preferable to combine a side chain having a crosslinkable functional group (for example, a double bond) with the main chain, or to combine a side chain having a function of aligning liquid crystalline molecules. The linking functional group is introduced into the side chain.

As the polymer used for the alignment film, any of polymers that can be cross-linked by itself or polymers that can be cross-linked with a cross-linking agent can be used, and multiple combinations of these can also be used. Examples of polymers include methacrylate copolymers, styrene copolymers, polyolefins, polyvinyl alcohol and modified polyvinyl alcohol, Poly(N-methylolacrylamide), polyester, polyimide, vinyl acetate copolymer, carboxymethyl cellulose and polycarbonate, etc. Organosilane coupling agents can also be used as polymers. As the aforementioned polymer, water-soluble polymers (such as poly(N-methylolacrylamide), carboxymethylcellulose, keratin, polyvinyl alcohol and modified polyvinyl alcohol) are preferable, and keratin, polyvinyl alcohol and modified polyvinyl alcohol are more preferable. Modified polyvinyl alcohol, most preferably polyvinyl alcohol and modified polyvinyl alcohol. It is particularly preferable to use together two kinds of polyvinyl alcohols and modified polyvinyl alcohols having different degrees of polymerization. The degree of saponification of polyvinyl alcohol is preferably 70 to 100%, more preferably 80 to 100%. It is preferable that the mass average degree of polymerization of polyvinyl alcohol is 100-5000.

A side chain having a function of aligning liquid crystalline molecules generally has a hydrophobic group as a functional group. The specific type of functional group can be determined according to the type of liquid crystal molecules and the necessary alignment state. For example, as a modifying group of modified polyvinyl alcohol, it can be introduced by copolymerization modification, chain transfer modification or block copolymerization modification. Examples of modifying groups include hydrophilic groups (carboxylic acid groups, sulfonic acid groups, phosphonic acid groups, amino groups, ammonium groups, amido groups, and thiol groups, etc.), carbon numbers of 10 to 100 Hydrocarbon group, fluorine atom substituted hydrocarbon group, thioether group, polymer group (unsaturated polymer group, epoxy group and aziridyl group, etc.), alkoxysilyl group (trialkoxy, dialkoxy and monoalkoxy) Oxygen) etc. Specific examples of these modified polyvinyl alcohol compounds include paragraph numbers [0022] to [0145] in the specification of JP-A-2000-155216 and paragraph numbers [0018] in the specification of JP-A-2002-62426. ~ [0022] in the recorded material.

If the side chain with the cross-linking functional group is combined on the main chain of the polymer, or the cross-linking functional group is introduced into the side chain having the function of aligning the liquid crystal molecules, the polymer of the alignment film and the optical Copolymerization of polyfunctional monomers in the anisotropic layer. As a result, not only between the multifunctional monomer and the multifunctional monomer, between the alignment film polymer and the alignment film polymer, but also between the multifunctional monomer and the alignment film polymer, are firmly bonded together. combined. Therefore, the strength of the optical compensation sheet can be remarkably improved by introducing a crosslinkable functional group into the alignment film polymer.

The crosslinkable functional group of the polymer for the alignment film preferably contains a polymerizable group similarly to the polyfunctional monomer. Specifically, for example, those described in paragraph numbers [0080] to [0100] in the specification of JP-A-2000-155216 can be mentioned. The alignment film polymer may be crosslinked using a crosslinking agent in addition to the above-mentioned crosslinkable functional groups.

As the crosslinking agent, aldehydes, N-methylol compounds, dioxane derivatives and compounds that function by activating carbonyl groups, active vinyl compounds, active halogen compounds, isoxazoles, and dialdehyde starches are included. It is also possible to use two or more crosslinking agents simultaneously. Specifically, for example, compounds described in paragraphs [0023] to [0024] in the specification of JP-A-2002-62426 and the like can be mentioned. As the above-mentioned crosslinking agent, aldehydes with high reactivity, especially glutaraldehyde, are preferable.

The amount of the crosslinking agent added is preferably 0.1 to 20% by mass, more preferably 0.5 to 15% by mass, based on the polymer. The amount of unreacted crosslinking agent remaining in the alignment film is preferably less than or equal to 1.0 mass%, more preferably less than or equal to 0.5 mass%. By adjusting in this way, even if the alignment film is used in a liquid crystal display device for a long period of time, or left in a high-temperature and high-humidity atmosphere for a long period of time, shrinkage does not occur, and more sufficient durability can be obtained.

The alignment film is basically formed by applying the above-mentioned polymer as an alignment film forming material and a transparent support containing a crosslinking agent, followed by heat drying (crosslinking), followed by rubbing. The crosslinking reaction can be carried out at any time after coating on the transparent support as described above. When a water-soluble polymer such as polyvinyl alcohol is used as the material for forming the alignment film, the coating liquid is preferably a mixed solvent of an organic solvent (such as methanol) having a defoaming effect and water. The ratio of water:methanol is preferably 0:100 to 99:1 in mass ratio, more preferably 0:100 to 91:9. This suppresses the generation of air bubbles and remarkably reduces defects on the layer surfaces of the alignment film and the optically anisotropic layer.

The coating method of the alignment film is preferably a spin coating method, a dip coating method, a curtain coating method, an extrusion coating method, a rod coating method, and a roll coating method. Particularly preferred is the rod coating method. In addition, the film thickness after drying is preferably 0.1 to 10 μm. Drying by heating can be performed at, for example, 20°C to 110°C. In order to form sufficient crosslinking, it is preferably 60°C to 100°C, particularly preferably 80°C to 100°C. The drying time can be performed for 1 minute to 36 hours, but preferably 1 minute to 30 minutes. The pH is also preferably set to an optimum value for the crosslinking agent used, and when glutaraldehyde is used, it is preferably pH 4.5 to 5.5, particularly preferably pH 5.

The orientation film is provided on the cellulose acylate film of the present invention or on the undercoat layer coated on the film. The alignment film is obtained by subjecting the surface to a rubbing treatment after crosslinking the polymer as described above.

The above-mentioned rubbing treatment can use a treatment method widely used as a liquid crystal alignment treatment process of LCD. That is, the orientation can be obtained by rubbing the surface of the alignment film in a certain direction using paper, gauze, felt, rubber, nylon, polyester fiber, or the like. Generally, it implements by rubbing several times using the cloth etc. which uniformly implanted the fiber of uniform length and thickness.

In the case of industrial implementation, it can be realized by making a rotating rubbing roller contact the film attached to the orientation film being transported, but it is preferable that the roundness, cylindricity, and vibration (eccentricity) of the rubbing roller are all less than or equal to 30 μm. The overlapping portion of the film on the rubbing roll is preferably 0.1 to 90°. However, as described in JP-A-8-160430, a stable rubbing treatment can also be obtained by winding at 360° or more. The conveying speed of the film is preferably 1 to 100 m/min. As for the friction angle, it is preferable to select an appropriate friction angle in the range of 0° to 6°. When used in a liquid crystal display device, it is preferably 40 to 50°. Particular preference is given to 45°.

The film thickness of the alignment film obtained in this way is preferably in the range of 0.1 to 10 μm.

Next, the liquid crystalline molecules of the optically anisotropic layer are aligned on the alignment film. Thereafter, the alignment film polymer is reacted with the polyfunctional monomer contained in the optically anisotropic layer as necessary, or the alignment film polymer is crosslinked using a crosslinking agent.

The liquid crystalline molecules used in the optically anisotropic layer include rod-shaped liquid crystalline molecules and discotic liquid crystalline molecules. The rod-like liquid crystalline molecules and the discotic liquid crystalline molecules may be high-molecular liquid crystals or low-molecular liquid crystals, and low-molecular liquid crystals may be cross-linked so as not to exhibit liquid crystallinity.

(O-2) Rod-shaped liquid crystal molecules

As the rod-shaped liquid crystal molecules, preferably used are methyl imines, azo oxide compounds, cyanobiphenyls, cyanophenyl esters, benzoate esters, phenylcyclohexane carboxylate, cyanobenzene Cyclohexanes, cyano-substituted phenylpyrimidines, alkoxy-substituted phenylpyrimidines, phenyldioxanes, phenyltolanes and alkenylcyclohexylbenzocyanides.

In addition, rod-like liquid crystal molecules contain metal complexes. Furthermore, going back to the rod-like liquid crystalline molecules, the liquid crystal polymer contained in the unit can also be used as the rod-like liquid crystalline molecules. In other words, rod-like liquid crystalline molecules can also be combined with (liquid crystal) polymers.

About the rod-like liquid crystal molecules, in Chapter 4, Chapter 7, and Chapter 11 edited by the Chemical Society of Japan, Chapter 4, Chapter 7, and Chapter 11 of the Quarterly Journal of Chemistry, Vol. It is documented in Chapter 3.

The birefringence of the rod-shaped liquid crystalline molecules is preferably in the range of 0.001 to 0.7.

In order to fix the alignment state, the rod-like liquid crystalline molecules preferably have a polymerizable group. The polymerizable group is preferably a free polymerizable unsaturated group or a cationic polymerizable group. Specifically, for example, the polymerizable groups described in paragraphs [0064] to [0086] of JP-A-2002-62427 and Polymeric liquid crystal compound.

(口—3) discotic liquid crystal molecules

Discotic liquid crystalline molecules include benzene derivatives described in the research report of C. Destrade et al., Mol. Cryst. Vol. 71, page 111 (1981), and the research report of C. Destrade et al., Mol. Cryst. 122 Volume, 141 pages (1985), Physics lett, A, 78 volumes, 82 pages (1990), the research report of B.Kohne et al., Angew.Chem.96 volumes, 70 pages ( Cyclohexane derivatives described in 1984), and the research report of J.M.Lehn et al., J.Chem Commun., 1794 pages (1985), the research report of J.Zhang et al., J.Am.Chem.Soc.116 Vol. 2655 (1994) of the azacorona or phenylacetylene macrocyclic compounds.

Examples of discotic liquid crystalline molecules include liquid crystalline compounds having a structure in which straight-chain alkyl groups, alkoxy groups, and substituted benzoic acid groups are radially substituted as side chains of the core core with respect to the core core at the center of the molecule. The aforementioned discotic liquid crystalline molecules, molecules or aggregates of molecules have rotational symmetry, and are preferably compounds that can impart a certain orientation. As the optically anisotropic layer formed of discotic liquid crystalline molecules, the compound finally included in the optically anisotropic layer does not necessarily have to be discotic liquid crystalline molecules, for example, compounds having low molecular discotic A group that reacts liquid crystal molecules with heat or light, and as a result, polymerizes or crosslinks due to thermal reaction to increase its molecular weight and lose liquid crystallinity. Preferred discotic liquid crystalline molecules are described in JP-A-8-50206. In addition, 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 a disc-shaped core and a polymerizable group are assembled via a linker is preferable so that the aligned state can be maintained even during the polymerization reaction. For example, compounds described in paragraphs [0151] to [0168] in the specification of JP-A-2000-155216 and the like can be mentioned.

In the mixed orientation, the angle between the long axis (disk plane) of the discotic liquid crystal molecules and the plane of the polarizing film, with respect to the depth direction of the optically anisotropic layer, and increases simultaneously with the increase of the distance from the plane of the polarizing film increase or decrease. The angle preferably decreases simultaneously with increasing distance. Also, as the change in angle, there may be continuous increase, continuous decrease, intermittent increase, intermittent decrease, a change including continuous increase and continuous decrease, or an intermittent change including increase and decrease. Discontinuous changes include regions where the inclination angle does not change in the middle of the thickness direction. The angle may include a region where the angle does not change, and may be increased or decreased as a whole. Furthermore, a continuous change in angle is preferred.

The average direction of the major axis of the discotic liquid crystal molecules on the polarizing film side can generally be adjusted by selecting the material of the discotic liquid crystal molecules or the alignment film, or by selecting a rubbing treatment method. In addition, the direction of the major axis (disc surface) of the discotic liquid crystalline molecules on the surface side (air side) can generally be determined by selecting the type of discotic liquid crystalline molecules or additives used together with the discotic liquid crystalline molecules. Adjustment. Examples of additives used together with discotic liquid crystalline molecules include plasticizers, surfactants, polymerizable monomers and polymers, and the like. The degree of change in the long-axis alignment direction can also be adjusted by selecting liquid crystalline molecules and additives in the same manner as above.

(ロ-4) Other compositions of the optically anisotropic layer

Using plasticizers, surfactants, polymerizable monomers, etc. together with the above-mentioned liquid crystal molecules can improve the uniformity of the coating film, the strength of the film, the orientation of the liquid crystal molecules, and the like. These preferably have compatibility with liquid crystalline molecules, change the tilt angle of liquid crystalline molecules, or do not interfere with alignment.

As said polymerizable monomer, a free polymerizable or cation polymerizable compound is mentioned, for example. Polyfunctional freely polymerizable monomers are preferred, and the aforementioned polymerizable group-containing liquid crystal compounds and copolymerizable substances are preferred. Examples of the polymerizable monomer include those described in paragraphs [0018] to [0020] in the specification of JP-A-2002-296423. The amount of the polymerizable monomer added is in the range of 1 to 50% by mass, preferably in the range of 5 to 30% by mass, based on the discotic liquid crystalline molecules.

Examples of the surfactant include conventionally known compounds, particularly preferably fluorine-based compounds. Specifically, for example, compounds described in paragraphs [0028] to [0056] in the specification of JP-A-2001-330725 can be mentioned.

The polymer used together with the discotic liquid crystalline molecules preferably changes the tilt angle of the discotic liquid crystalline molecules.

Examples of such polymers include cellulose esters. Preferable examples of cellulose esters include those described in paragraph [0178] of JP-A-2000-155216. In order not to interfere with the orientation of the liquid crystalline molecules, the amount of the polymer added is preferably in the range of 0.1 to 10% by mass, more preferably in the range of 0.1 to 8% by mass, based on the liquid crystalline molecules.

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.

(口-5) Formation of optically anisotropic layer

The optically anisotropic layer can be formed by applying liquid crystalline molecules and, if necessary, a coating liquid containing a polymerizable initiator and optional components described later on the alignment film.

It is preferable to use an organic solvent as the solvent used for preparing the coating liquid. Examples of organic solvents include amides (such as N,N-dimethylformamide), sulfoxides (such as dimethylsulfoxide), heterocyclic compounds (such as pyridine), hydrocarbons (such as benzene and hexane), alkylhalogenated substances (such as chloroform, dichloromethane, tetrachloroethane), esters (such as methyl acetate, butyl acetate), ketones (such as acetone, methyl ethyl ketone), and ethers (such as tetrahydrofuran, 1, 2-dimethoxyethane). Alkyl halides and ketones are preferred. It is also possible to use two or more organic solvents together.

Coating of the coating liquid can be carried out by a known method (for example, bar coating method, extrusion coating method, direct gravure coating method, reverse gravure coating method, die coating method).

The thickness of the optically anisotropic layer is preferably 0.1 to 20 μm, more preferably 0.5 to 15 μm, most preferably 1 to 10 μm.

(口-6) Fixation of orientation state of liquid crystalline molecules

The aligned liquid crystalline molecules can be fixed while maintaining the aligned state. Immobilization is preferably carried out by polymerization. The polymerization reaction includes a thermal polymerization reaction using a thermal polymerization initiator and a photopolymerization reaction using a photopolymerization initiator. As the above-mentioned polymerization reaction, photopolymerization reaction is preferable.

Examples of photopolymerization initiators include α-carbonyl compounds (described in the descriptions of U.S. Patent No. 2,367,661 and U.S. Patent No. 2,367,670 ), diinyl ethers (described in the descriptions of U.S. Patent No. 2,448,828 ), α- Hydroxy-substituted aromatic compound (described in the specification of US Patent No. 2722512), polynuclear quinone compound (described in the specification of US Patent No. 3046127 and US Patent No. 2951758), triaryl imidazole dimer Combination with p-aminobenzophenone (described in the specification of U.S. Patent No. 3549367), acridine and phenazine compound (described in the specification of JP-A-60-105667, U.S. Patent No. 4239850) and oxine Oxadiazole compound (described in the specification of US Patent No. 4212970).

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 liquid.

For light irradiation for polymerization of liquid crystalline molecules, it is preferable to use ultraviolet rays.

The irradiation energy is preferably in the range of 20 mJ/cm ² to 50 J/cm ² , more preferably in the range of 20 to 5000 mJ/cm ² , and most preferably in the range of 100 to 800 mJ/cm ² . In addition, in order to promote the photopolymerization reaction, light irradiation may be performed under heating conditions.

In addition, a protective layer may be provided on the optically anisotropic layer.

It is preferable to combine a polarizing layer and the optical compensation film. Specifically, the optically anisotropic layer is formed by coating the aforementioned coating liquid for an optically anisotropic layer on the surface of the polarizing film. As a result, without using a polymer film between the polarizing film and the optically anisotropic layer, it is possible to manufacture a thin polarizing plate with little stress (distortion×sectional area×elastic modulus) due to dimensional changes of the polarizing film. When the polarizing plate comprising the cellulose acylate film of the present invention is mounted on a large liquid crystal display device, images of high display quality can be displayed without causing problems such as light leakage.

The inclination angles of the polarizing film and the optical compensation layer are preferably stretched such that the angles formed between the transmission axes of the two polarizing plates attached to both sides of the liquid crystal cell constituting the LCD and the vertical or horizontal direction of the liquid crystal cell are consistent. The general inclination angle is 45°. However, recently, a device that does not necessarily have to be 45° in transmissive, reflective, or semi-transmissive LCDs has been developed, and it is preferable that the stretching direction can be arbitrarily adjusted in combination with the design of the LCD.

(ロ-7) liquid crystal display device

Each liquid crystal type using such an optical compensation film will be described.

TN type liquid crystal display device:

The TN-type liquid crystal display device is most widely used as a color TFT liquid crystal display device, and is described in many documents. The alignment state of the liquid crystal cell in the black display of the TN type is an alignment state in which the rod-shaped liquid crystal molecules stand upright in the center of the cell, and the rod-shaped liquid crystal molecules lie horizontally near the substrate of the cell.

OCB type liquid crystal display device:

The OCB type liquid crystal display device is a bend alignment type liquid crystal cell in which rod-shaped liquid crystal molecules are actually aligned in opposite directions (symmetrically) at the upper and lower parts of the liquid crystal cell. A liquid crystal display device using a bend alignment liquid crystal cell is disclosed in US Patent No. 4,583,825 and US Patent No. 4,510,422. Since the rod-shaped liquid crystal molecules are symmetrically aligned on the upper and lower parts of the liquid crystal cell, the liquid crystal cell of the bend alignment type has an optical self-compensation function. Therefore, this liquid crystal type is also called OCB (Optically Compensatory Bend) liquid crystal type.

The OCB-type liquid crystal cell is also the same as the TN-type liquid crystal cell. In the black display, the alignment state of the liquid crystal cell is that the rod-shaped liquid crystal molecules are upright in the center of the element, and the rod-shaped liquid crystal molecules are lying down near the substrate of the element.

VA type liquid crystal display device:

The characteristic of the VA-type liquid crystal display device is that when no voltage is applied, the rod-like liquid crystal molecules are actually vertically aligned. In the VA-type liquid crystal cell, it includes: (1) when no voltage is applied, the rod-like liquid crystal molecules are actually vertically aligned , the narrow sense VA-type liquid crystal unit that is actually horizontally oriented when a voltage is applied; on this basis, (2) in order to expand the viewing angle, the VA type is divided into multiple regions (MVA-type) liquid crystal cells (SID97, Digest of tech.Papers (recorded in draft compilation) 28 (1997) 845); (3) When no voltage is applied, the rod-shaped liquid crystal molecules are actually aligned vertically, and when a voltage is applied, they are twisted and partitioned to form an alignment type (n-ASM type) Liquid crystal cell (described in Japanese Liquid Crystal Symposium 58-59 (1998)); and (4) SURVAIVAL type liquid crystal cell (published in LCD International 98).

IPS type liquid crystal display device:

The IPS type liquid crystal display device is characterized in that the rod-shaped liquid crystal molecules are substantially aligned horizontally in the plane when no voltage is applied, and is also characterized in that the alignment direction of the liquid crystal is changed and switched depending on whether a voltage is applied. Specifically can be used in JP-A-2004-365941, JP-A-2004-12731, JP-A-2004-215620, JP-A-2002-221726, JP-A-2002-55341, JP-A-2003-195333 The device described in the bulletin.

Other LCD devices:

For ECB type and STN (Super Twisted Nematic) type liquid crystal display devices, optical compensation can be performed in the same way as above.

(ハ) Formation of anti-reflection layer (manufacture of anti-reflection film)

As an antireflection film, generally on the substrate as the cellulose acylate film of the present invention, a low-refractive-index layer of an anti-pollution layer and at least one layer having a higher refractive index than the low-refractive-index layer (i.e. high refractive index layer, medium refractive index layer).

As a method for forming a multilayer film in which transparent thin films of inorganic compounds (metal oxides, etc.) with different refractive indices are laminated, chemical vapor deposition (CVD) and physical vapor deposition (PVD), and metal alkoxides After forming a colloidal metal oxide particle film by a sol-gel method, a metal compound such as , is subjected to post-treatment (irradiation of ultraviolet light: JP-A-9-157855, plasma treatment: JP-A-2002-327310) to form a thin film Methods.

On the other hand, as highly productive antireflection films, various antireflection films in which thin films in which inorganic particles are dispersed in an array are laminated and coated have been proposed.

In addition, examples of the antireflection layer include antireflection films formed by forming an antireflection layer having a fine unevenness on the uppermost surface of the antireflection film formed by coating to impart antiglare performance.

For the cellulose acylate film of the present invention, any of the above-mentioned methods can be used, and the method of coating (coating type) is particularly preferable.

(ハ-1) Layer composition of coating type antireflection film

On the base material as the cellulose acylate film of the present invention, at least by the antireflection film that constitutes by the layer structure of middle refractive index layer, high refractive index layer and low refractive index layer (outermost layer), be designed to have satisfying following The relational index of refraction.

Relational formula...Refractive index of high refractive index layer>Refractive index of middle refractive index layer>Refractive index of transparent support>Refractive index of low refractive index layer

In addition, a hard coat layer may be provided between the transparent support and the medium refractive index layer. In addition, the antireflection film may also be composed of a medium-refractive-index hard coat layer, a high-refractive-index layer, and a low-refractive-index layer.

Examples of the antireflection film include JP-A-8-122504, JP-A-8-110401, JP-10-300902, JP-2002-243906 and JP-2000-111706.

In addition, each of the above-mentioned layers can also have other functions, for example, anti-pollution low-refractive index layer, anti-static high-refractive index layer (for example, JP-A-10-206603, JP-A-2002-243906 Bulletin), etc.

The haze of the antireflection film is preferably 5% or less, more preferably 3% or less. In addition, the strength of the film is preferably equal to or greater than H, more preferably equal to or greater than 2H, and most preferably equal to or greater than 3H in accordance with the JIS K5400 pencil hardness test.

(ハ—2) High refractive index layer and medium refractive index layer

The high-refractive-index layer (high-refractive-index layer) of the antireflection film is composed of a curable film containing at least high-refractive-index inorganic compound ultrafine particles with an average particle diameter of 100 nm or less and an array adhesive.

Examples of the inorganic compound fine particles of the high refractive index layer include inorganic compounds having a refractive index of 1.65 or more, and preferably a refractive index of 1.9 or more. Examples of high refractive index inorganic compound ultrafine particles include oxides of Ti, Zn, Sb, Sn, Zr, Ce, Ta, La, In, etc., composite oxides containing these metal atoms, and the like.

In order to form such ultrafine particles, the technique of treating the particle surface with a surface treatment agent (such as a silane coupling agent: JP-P 11-295503, JP-11-153703 and JP-2001-9908 , anionic compound or organometallic alkane coupling agent: JP-A No. 2001-310432, etc.), technology of a core-coat structure using high-refractive-index particles as the core (JP-A-2001-166104, etc.), and a specific dispersant Used together (JP-A-11-153703, US Patent No. 6210858, JP-A-2002-2776069, etc.), etc.

Examples of the material for forming the array include known thermoplastic resins, curable resin films, and the like.

In addition, as the material for forming the array, it is preferable to use a composition containing a polyfunctional compound containing at least two or more free polymerizable and/or cationic polymerizable polymerizable groups, an organometallic compound containing a hydrolyzable group A composition of at least one selected from the compound and its partial condensate composition. Examples thereof include compounds described in JP-A-2000-47004, JP-A-2001-315242, JP-A-2001-31871, JP-A-2001-296401 and the like.

In addition, colloidal metal oxides obtained from hydrolysis condensates of metal alkoxides and curable films obtained from metal alkoxide compositions are preferred. This curable film is described, for example, in JP-A-2001-293818 and the like.

The refractive index of the high refractive index layer is usually 1.70 to 2.20. The thickness of the high refractive index layer is preferably 5 nm to 10 μm, more preferably 10 nm to 1 μm.

The refractive index of the middle refractive index layer is adjusted to 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.

(ハ—3) Low refractive index layer

The low-refractive-index layer is sequentially stacked on the high-refractive-index layer. The refractive index of the low refractive index layer is preferably 1.20 to 1.55, more preferably 1.30 to 1.50.

The above-mentioned low-refractive index layer preferably constitutes the outermost layer having scratch resistance and anti-pollution performance. As a method of improving scratch resistance, it is effective to impart lubricating properties to the surface, and conventionally known methods such as introduction of silicon by silicon compounds, introduction of fluorine by fluorine compounds, etc. can be used to form a thin film layer.

The refractive index of the fluorine-containing compound is preferably 1.35 to 1.50, more preferably 1.36 to 1.47. In addition, the fluorine-containing compound is preferably a crosslinkable or polymerizable functional group-containing compound having fluorine atoms in the range of 35 to 80% by mass.

As the above-mentioned fluorine compound, for example, paragraph numbers [0018] to [0026] in the specification of JP-A-9-222503, paragraph numbers [0019]-[0030] in the specification of JP-A-11-38202, Paragraph numbers [0027] to [0028] in the specification of JP 2001-40284, paragraph numbers [0012] to [0077] in JP 2000-284102, JP 2003-26732, JP 2004- Compounds described in paragraphs [0030] to [0047] of Publication No. 45462.

The organosilicon compound is a compound having a polysiloxane structure, contains a curable functional group or a polymerizable functional group in a polymer chain, and preferably has a crosslinked structure in a film. For example, reactive silicone (for example, Silaplane (manufactured by Chisso Co., Ltd., etc.), polysiloxane containing silanol groups at both terminals (JP-A-11-258403, etc.) and the like are mentioned.

The crosslinking or polymerization reaction of the fluorine-containing and/or polysiloxane polymer having a crosslinkable group or a polymerizable group is preferably carried out by coating a polymer containing a polymerization initiator or a sensitizer, etc. Simultaneously with or after coating the coating composition forming the outermost layer, light irradiation or heating is performed.

In addition, as the low refractive index layer, an organometallic compound such as a silane coupling agent and a silane coupling agent containing a specific fluorine-containing hydrocarbon group are preferable, and a sol-gel cured film that is hardened by a condensation reaction in the presence of a catalyst .

For example, as a silane coupling agent, an organosilicon compound containing a polyfluoroalkyl group or a partial hydrolysis condensate thereof (JP-A-58-142958, JP-A-58-147438, JP-A-58 -147484 bulletin, JP-A-9-157582, JP-A-11-106704, etc.), silyl compounds containing (poly)perfluoroalkyl ether groups as fluorine-containing long-chain groups ( Compounds described in JP-A-2000-117902, JP-A-2001-48590, JP-A-2002-53804, etc.) and the like.

As additives other than the above, the low-refractive index layer may contain fillers (such as silicon dioxide (silica), fluorine-containing particles (magnesium fluoride, calcium fluoride, barium fluoride), etc. Primary particles with an average particle diameter of 1 to 150 nm low refractive index inorganic compounds, organic fine particles described in paragraphs [0020] to [0038] of JP-A-11-3820, etc.), silane coupling agents, lubricants, surfactants, etc.

When the low-refractive-index layer is located under the outermost layer, the low-refractive-index layer can be formed by a vapor phase method (vacuum evaporation method, sputtering method, ion plating method, plasma CVD method, etc.). The coating method is preferable because it can be manufactured at low cost.

The film thickness of the low refractive index layer is preferably 30 to 200 nm, more preferably 50 to 150 nm, and most preferably 60 to 120 nm.

(ハ—4) hard coating

The hard coat layer is used to impart physical strength to the antireflection film, and is provided on the surface of the substrate as the cellulose acylate film of the present invention. It is particularly preferably provided between the substrate and the above-mentioned high refractive index layer.

The hard coat layer is preferably formed by a crosslinking reaction or polymerization reaction of a curable compound with light and/or heat. The curable functional group of the curable compound is preferably a photopolymerizable functional group, and the organometallic compound containing a hydrolyzable functional group is preferably an organoalkoxysilyl compound.

Specific examples of these compounds include the same examples as those shown for the high refractive index layer.

Specific constituents of the hard coat layer include, for example, those described in JP-A-2002-144913, JP-A-2000-9908, and International Publication WO0/46617.

In addition, the above-mentioned high refractive index layer may also serve as a hard coat layer. In this case, it is preferable to form fine particles finely dispersed and contained in the hard coat layer by the method described in the high refractive index layer.

The hard coat layer may also contain particles with an average particle diameter of 0.2 to 10 μm to also serve as an antiglare layer (described later) to provide an antiglare function.

The film thickness of a hard-coat layer can be suitably designed according to a use. 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 is tested by the pencil hardness of JIS K5400, preferably greater than or equal to H, more preferably greater than or equal to 2H, most preferably greater than or equal to 3H. In addition, in the cone test according to JIS K5400, it is preferable that the wear amount of the sample before and after the test is as small as possible.

(ハ—5) forward scattering layer

The forward scattering layer is designed to improve the viewing angle effect when the viewing angle is tilted in the up, down, left, and right directions when it is used in a liquid crystal display device. It is also possible to combine the function of the hard coat layer by dispersing fine particles having different refractive indices in the above-mentioned hard coat layer.

As the forward scattering layer, for example, JP-A No. 11-38208 in which the forward scattering coefficient is specified, JP-A No. 2000-199809 in which the relative refractive index of the transparent resin and fine particles is within a specific range, and the turbidity The value of JP-A No. 2002-107512 and the like are specified to be greater than or equal to 40%.

(ハ—6) other layers

In addition to the above-mentioned layers, an antistatic layer, an undercoat layer, a protective layer, and the like may be provided on the cellulose acylate film of the present invention.

(ハ—7) Coating method

Each layer of the anti-reflection film can be coated by dip coating, blowing coating, curtain coating, roll coating, bar coating, gravure coating, micro gravure coating, extrusion coating method (US Patent No. 2681294 specification), formed by coating.

(ハ—8) Anti-glare function

The antireflection film may also have an antiglare function of scattering external light. The antiglare function can be obtained by forming unevenness on the surface of the antireflection film. In the case where the antireflection film has an antiglare function, the haze of the antireflection film is preferably 3 to 30%, more preferably 5 to 20%, most preferably 7 to 20%.

Any method of forming concavities and convexities on the antireflection film can be used as long as the method can sufficiently maintain their surface shape. For example, in the method of using fine particles in the low-refractive index layer to form unevenness on the film surface (for example, JP-A-2000-271878, etc.), the lower layer of the low-refractive index layer (high-refractive-index layer, medium-refractive-index layer or hard A small amount (0.1 to 50% by mass) of relatively large particles (0.05 to 2 μm in particle size) are added on the coating) to form a surface concave-convex film, and the method of setting a low refractive index layer on it by maintaining their shape (such as JP-A 2000-281410, JP-A 2000-95893, JP-A 2001-100004, JP-A 2001-281407, etc.), physically replicating concavities and convexities on the surface after coating the top layer (anti-pollution layer) The method of shape (for example, as an embossing method, it is described in JP-A-63-278839, JP-A-11-183710, JP-A-2000-275401, etc.) and the like.

(Measurement methods)

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

1. Aging change rate of Re and Rth

(1) Measurement before aging

After adjusting the humidity of the sample film at 25°C and a relative humidity of 60% for 3 hours or more, use an automatic birefringence meter (KOBRA-21ADH/PR: manufactured by Oji Scientific Instruments Co., Ltd.) Under the condition of a humidity of 60%, the retardation value at a wavelength of 550 nm was measured from a direction perpendicular to the surface of the sample film and a direction inclined ±40° from the normal line of the film surface. The in-plane retardation (Re) was calculated from the measured value in the vertical direction, and the retardation in the thickness direction (Rth) was calculated from the measured value in the direction inclined by ±40° from the normal line of the film surface. Let them be Re(F) and Rth(F).

(2) Measurement after aging

As conditions equivalent to natural aging for 10 years or more, after aging for 1,000 hours at 80°C and a relative humidity of 10% or less, adjust the humidity for 3 hours or 3 hours at 25°C and a relative humidity of 60% After the above, under conditions of 25° C. and a relative humidity of 60%, Re and Rth were measured in the same manner as the measurement before aging. Let them be Re(T) and Rth(T).

(3) From these values, the aging change rate of Re and Rth can be obtained according to the following formula. Aging change rate of Re (%: δRe) =

100×|Re(F)-Re(T)|/Re(F)

Rth aging change rate (%: δRth) =

100×|Rth(F)-Rth(T)|/Rth(F)

2. Surface waviness height

(1) The sample film is cut into a 50-cm square parallel to the film-forming direction. Make it age for 1000 hours under the conditions of 80° C. and relative humidity less than or equal to 10%.

(2) After aging for 1000 hours at 80°C and a relative humidity of 10% or less, spread the sample film on a horizontal, smooth table, and after aging for 12 hours at 25°C and a relative humidity of 60%, the At all positions where surface waviness is formed, use a vernier caliper to measure the height raised from the table due to surface waviness.

(3) The maximum height (the maximum distance from the table top to the film) among all the measurement points is called the surface waviness height.

3. Aspect ratio (L/W)

The aspect ratio (L/W) is expressed by dividing the interval between the nip rolls used for stretching (L: the distance between the rotation center axes of two pairs of nip rolls) by the width of the cellulose acylate film before stretching (W) The resulting value (L/W). Also, when there are three or more pairs of nip rolls, the largest L/W value is taken as the aspect ratio (L/W).

4. Degree of substitution of cellulose acylate resin

The degree of acyl substitution of cellulose acylate resin is determined by ¹³ C-NMR according to the method described in Carbohydr. Res. 273 (1995) 83-91 (Tezuka et al.).

Examples are given below to further describe the present invention in detail. Materials, usage amounts, proportions, processing contents, processing procedures, and the like shown in the following examples can be appropriately changed as long as they do not depart from the gist of the present invention. Therefore, the scope of the present invention is not limited to the specific examples shown below.

1. Cellulose acylate resin

As described in the following Tables 1 and 2, cellulose acylate resins having different types of acyl groups and degrees of substitution were prepared. Sulfuric acid (7.8 parts by mass relative to 100 parts by mass of cellulose) was added as a catalyst, and carboxylic acid as a raw material for acyl substituting groups was added, and acylation reaction was carried out at 40°C to prepare cellulose acylate resin . At this time, by adjusting the type and amount of carboxylic acid, the type and degree of substitution of the acyl group can be adjusted. In addition, aging was performed at 40° C. after acylation. The degree of polymerization of the cellulose acylate resin thus obtained was determined by the following method, and is described in Tables 1 and 2.

(Measuring method of degree of polymerization)

About 0.2 g of absolutely dry cellulose acylate resin was accurately weighed out, and dissolved in 100 ml of a mixed solvent of methylene chloride:ethanol=9:1 (mass ratio). The number of seconds it takes for it to fall at 25° C. in an Ostwald viscometer is measured, and the degree of polymerization is obtained by the following formula.

H _rel ＝T/T ₀ T: Measure the falling seconds of the sample

[η]=[ln(η _rel )]/C TO: the number of seconds the solvent falls alone

DP＝[η]/Km C: Concentration (g/l)

Km: 6×10 ^-4

ln: natural logarithm

Tg of each cellulose acylate resin was measured by the following method, and is described in Tables 1 and 2. In addition, the value measured after addition of a plasticizer is shown for the one which added a plasticizer.

(Tg measurement)

Put 20mg of the sample into the DSC measuring dish, heat it up from 30°C to 250°C (1st-run) at a rate of 10°C/min in a nitrogen stream, and then cool it at a rate of -10°C/min to 30°C. Thereafter, the temperature was raised again from 30°C to 250°C (2nd-run). The temperature at which the base line deviates from the low temperature side obtained by the above 2nd-run is defined as the glass transition temperature Tg, and is described in Tables 1 and 2.

In addition, 0.05% by mass of silica particles (Aerosil R 972 V: manufactured by Nippon Aerosil Co., Ltd.) was added horizontally.

2. Film making

(1) Melt film forming

The above cellulose acylate resin was molded into cylindrical pellets with a diameter of 3 mm and a length of 5 mm. At this time, plasticizers were selected from the following, and kneaded into pellets (described in Table 1). This was dried in a vacuum dryer at 110° C. to a moisture content of 0.1% by mass or less, and then placed in a hopper adjusted to (Tg-10)° C.

TPP: Triphenyl phosphate

BDP: bisphenyl diphenyl phosphate

DOA: bis(2-ethylhexyl)adipate

PTP: 1,4-Phenylenetetraphenyl Phosphate

The melting temperature was adjusted so that the melt viscosity was 1000 Pa·s, and the melt was melted at this temperature for 5 minutes using a single-screw kneader. Then, it is cast from a T-shaped die set at the same temperature as the melting temperature onto a casting drum set at (Tg-5° C.), and solidified to form a film. At this time, each horizontal electrostatic application method (a 10 kV lead wire was installed at a distance of 10 cm from the landing point of the casting drum of the melt) was used. The solidified melt was peeled off and taken up. In addition, both ends (each 3% of the entire width) were trimmed before coiling, and thickening (knurling) of 10 mm in width and 50 μm in height was performed on both ends. Each level was 1.5 m wide and 3000 m was coiled at the speed of 30 m/min.

(2) Solution film formation

(i) Feeding

The above-mentioned cellulose acylate resin was dried so that the moisture content was 0.1% by mass or less, and then the plasticizer described in Table 2 was added and dissolved in a solvent selected from the following. Then, the cellulose acylate resin was dissolved to 25% by mass.

Non-chlorinated organic solvents: methyl acetate/acetone/methanol/ethanol/butanol (80/5/7/5/3: parts by mass)

Chlorinated organic solvent: dichloromethane/butanol (94/6: parts by mass)

The plasticizer was selected from the above-mentioned TPP, BDP, DOA, and PTP, and the used ones are described in Table 2. In addition to this, the following additives were added at various levels.

・Optical anisotropy control agent: platy compound represented by (Chemical 1) described in JP-A-2003-66230 (3% by mass)

UV agent a: 2,4-bis-(n-octylthio)-6-(4-hydroxyl-3,5-di-tert-butylanilino)-1,3,5-triazine (0.5 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-phenyl)-5-chlorobenzotriazole (0.1% by mass)

・Fine particles: silica (particle size: 20nm), Mohs hardness about 7 (0.25% by mass)

・Ethyl citrate (monoester and diester mixed at 1:1, 0.2% by mass)

*All the above added amounts (% by mass) are ratios to cellulose acylate.

(ii) swelling, dissolution

These cellulose acylate resins, solvents and additives are added to the solvent while being stirred. Stirring was stopped after the addition was completed, and it was made to swell at 25° C. for 3 hours to prepare a slurry. This was stirred again to completely dissolve the cellulose acylate.

(iii) Filtration, Concentration

Then, it was filtered with a filter paper with an absolute filtration accuracy of 0.01 mm (Toyo Filter Paper Co., Ltd., #63), and then with a filter paper with an absolute filtration accuracy of 2.5 μm (Poll Co., Ltd., FH025).

(iv) Film making

The above-mentioned dopant was heated to 35° C., and cast by any of the following methods (described in Table 2).

(イ) belt method

Through an extruder (ギ-サ-), it was cast on a mirror-finished stainless steel support with a tape length of 60 m set at 15°C. The extruder used was similar to that described in JP-A-11-314233. In addition, the casting speed was 60 m/min, and the casting width was 250 cm.

After the residual solvent was peeled off at 100% by mass, it was dried at 130° C., and after the residual solvent was 1% by mass or less, it was wound up to obtain a cellulose acylate film. Both ends of the obtained film were trimmed by 3 cm, and knurls with a height of 100 μm were applied to portions 2 to 10 mm from both ends, and wound up into a 3000-m roll shape.

(ヴ) Roller method

Through an extruder, cast on mirror-finished stainless steel drums with a diameter of 3 m set at -15°C. The extruder used was similar to that described in JP-A-11-314233. In addition, the casting speed was 100 m/min, and the casting width thereof was 250 cm.

After the residual solvent was peeled off at 200% by mass, it was dried at 130° C., and after the residual solvent was 1% by mass or less, it was wound up to obtain a cellulose acylate film. Both ends of the obtained film were trimmed by 3 cm, and knurls with a height of 100 μm were applied to portions 2 to 10 mm from both ends, and wound up into a 3000-m roll shape.

3. Stretch

After preheating the cellulose acylate film obtained in the above-mentioned melt film forming or solution film forming using the temperature and the number of preheating rolls listed in Tables 1 and 2 below, the , using the nip rolls of the diameters described in Tables 1 and 2, stretching was performed at the aspect ratios described in Tables 1 and 2. In addition, the stretching temperature is expressed in Table 1 by several degrees higher or lower than the Tg of the resin at each level, respectively with + and - temperature as "relative". In addition, longitudinal stretching and lateral stretching are carried out at the same temperature. The rate of change of the cellulose acylate film meeting the requirements of the present invention stretched like this on total width, length direction Re, the rate of change of Rth (total width 10 is equally divided, will measure 10 times (totally 100 times) at intervals of 1m in the length direction The difference between the maximum value and the minimum value of points) divided by the average value, expressed as a percentage) is less than or equal to 2%.

Tables 1 and 2 show the Re and Rth of the thus obtained stretched film before aging (new), Re and Rth after aging at 80°C for 1000 hours, and the aging change rate of Re and Rth after aging at 80°C for 1000 hours. The height of the surface waviness after. At the same time, the sticking marks formed by the nip rolls were evaluated by the following method, which is described in Tables 1 and 2.

《Evaluation of Adhesion Marks》

The sample film was placed on a black flat cloth and observed visually with reflected light under a tungsten lamp. Observe the "ハ"-shaped (bird's toe-like) pattern that can be recognized on the surface of a ^20m2 film in the order of several mm, count the number, and express it as an average value per ^1m2 ("ハ"-shaped pattern Adhesion marks are produced when the film adheres when it touches the stretching roll, and then when the film is detached, the adhesion point is used as the starting point, and the surface of the film is peeled off radially).

4. Manufacture of polarizing plate

(1) Surface treatment

The stretched cellulose acylate film was saponified by any of the following methods, and is described in Tables 1 and 2.

(i) coating saponification

20 parts by mass of water was added to 80 parts by mass of iso-isopropanol, KOH was dissolved therein so as to have a temperature of 1.5 mol/L, and the solution adjusted to 60° C. was used as a saponification solution. On a cellulose acylate film at 60°C, it was coated at 10 g/m ² and saponified for 1 minute. thereafter. Spray 50°C warm water at 10 L/m ² ·min for 1 minute for cleaning.

(ii) Dipping saponification

Use 1.5mol/L NaOH aqueous solution as saponification solution. The temperature was adjusted to 60° C., and the cellulose acylate film was dipped for 2 minutes. Thereafter, after being immersed in a 0.05 mol/L sulfuric acid aqueous solution for 30 seconds, it passed through a water bath.

(2) Formation of polarizing film

According to Example 1 of JP-A-2001-141926, a polarizing film having a thickness of 20 μm was formed by stretching in the longitudinal direction by causing a peripheral speed difference between two pairs of nip rolls. At this time, a product after film formation and stretching, and a product after aging at 80° C. for 1,000 hours were manufactured. In addition, as described in Example 1 of JP-A-2002-86554, a polarizing film stretched so that the stretching axis was inclined at 45° was similarly produced, and the following evaluation results were the same as those of the above product.

(3) fit

Polarizing films produced using the thus obtained product immediately after stretching (new product) and the product aged at 80° C. for 1000 hours (aged product) were sandwiched between the stretched cellulose acylate film after the saponification treatment ( Retardation plate) and a saponified polarizer protective film (trade name: Fujitaku). At this time, the bonding of the phase difference plate and the polarizing layer uses a 3% aqueous solution of PVA (manufactured by Kuraray, PVA-117H) as an adhesive when the phase difference plate is cellulose acylate. If the board is made of other materials than this, it is pasted with an epoxy-based adhesive. In addition, the above-mentioned PVA aqueous solution was used as an adhesive to stick between Fujitaku and the polarizing film. The sticking direction is the direction in which the polarizing axis and the length direction of the phase difference plate form 45°. The polarizing plate thus obtained was mounted on a 20-inch VA-type liquid crystal described in FIGS. on the display device. The polarizing plate using the new product was compared with the polarizing plate using the aged product, and visually evaluated, and the ratio of the area where the color unevenness occurred to the entire area was recorded in Tables 1 and 2. Products embodying the invention achieve good properties.

5. Fabrication of Optical Compensation Film

The cellulose acylate film of the present invention was used instead of the cellulose acetate film coated with the liquid crystal layer of Example 1 of JP-A-11-316378. At this time, a product (new product) immediately after film forming and stretching and a product (aged product) aged at 80°C for 1000 hours were manufactured, and the two were compared, and the color unevenness occurred in the area. Visually evaluated, the ratio to the whole area is shown in Tables 1 and 2. In this way, a good optical compensation film can be produced by using the present invention.

In addition, instead of coating the cellulose acetate film of the liquid crystal layer in Example 1 of Japanese Patent Application Laid-Open No. 7-333433, the stretched cellulose acylate film of the present invention is changed to produce an optical compensation filter film, and it is also possible to produce into a good optical compensation film.

On the other hand, the products outside the scope of the present invention have lowered optical properties. Especially according to the product of Example 1 of JP-A-2002-311240 (comparative example 2-5 of Table 1), according to the product of sample No.S-11 in the examples of JA-2003-315551 ( In Comparative Example 2-4 in Table 2), the decrease in optical properties was particularly remarkable.

6. Manufacture of low reflection film

According to Example 47 of the Publication of the Invention Association (Public Technology No. 2001-1745), when the stretched cellulose acylate film of the present invention is used to form a low-reflection film, good optical properties are obtained.

7. Manufacture of liquid crystal display devices

The above-mentioned polarizing plate of the present invention is used in the liquid crystal display device described in Example 1 of JP-A-10-48420, and the coating containing discotic liquid crystal molecules described in Example 1 of JP-A-9-26572. An optically anisotropic layer, an alignment film of polyvinyl alcohol, a 20-inch VA-type liquid crystal display device described in FIGS. 2 to 9 of JP-A-2000-154261, and FIG. The 20-inch OCB type liquid crystal display device, and the IPS type liquid crystal display device described in FIG. 11 of JP-A-2004-12731. Further, when the cellulose acylate film of the present invention was attached to the outermost layer of these liquid crystal display devices and evaluated, a favorable liquid crystal display device was obtained.

Claims (16)

1. A cellulose acylate film, characterized in that the retardation Re in the plane is at 80 DEG C, the aging change rate δRe of 1000 hours under the condition of relative humidity being less than or equal to 10%, and the retardation Rth in the thickness direction is at 80 DEG C. The aging change rate δRth under 1000 hours is 0% to 10%, and the height of the surface waviness after aging is 0mm to 5mm. The acyl group of the cellulose acylate film satisfies the substitution degree represented by the following formula (1) and formula (2), Formula (1): 2.5≤A+B＜3.0 Formula (2): 1.25≤B<3.0 In the above formulas (1) and (2), A represents the degree of substitution of the acetyl group, and B represents the sum of the degrees of substitution of the propionyl, butyryl, pentanoyl and hexanoyl groups. 2. The cellulose acylate film according to claim 1, wherein the retardation Re in the plane is 0 nm to 500 nm, and the retardation Rth in the thickness direction is 30 nm to 500 nm. 3. cellulose acylate film according to claim 2, is characterized in that, the retardation Re of described plane and the retardation Rth of described thickness direction satisfy following formula, Re≤Rth. 4. The cellulose acylate film according to claim 1, wherein the film is a film formed by melt film forming. 5. cellulose acylate film according to claim 1, is characterized in that, this cellulose acylate film is made by such manufacturing method, and this manufacturing method comprises stretching process, when aspect ratio L/W exceeds Under the condition of 0.01 and less than 0.3, stretch the cellulose acylate sheet longitudinally to 1.01 to 3 times, In the stretching step, longitudinal stretching is carried out after passing 1 to 10 preheating rolls, The method further includes a step of drying the cellulose resin raw material to a moisture content of 0.1% or less, and a residual solvent amount in the film of 1% by mass or less at the time of stretching. 6. The cellulose acylate film according to claim 5, characterized in that, when more than or equal to 1/2 of the B is a propionyl group, the acyl group of the cellulose acylate sheet satisfies the following formula: (1A) and the degree of substitution represented by the following formula (2A), in the case where less than 1/2 of the B is a propionyl group, the acyl group of the cellulose acylate sheet satisfies the following formula (1A') and The degree of substitution represented by the following formula (2A'), Formula (1A): 2.6≤A+B≤2.95 Formula (2A): 2.0≤B≤2.95 Formula (1A'): 2.6≤A+B≤2.95 Formula (2A'): 1.3≤B≤2.5 7. The cellulose acylate film according to claim 5, wherein the preheating temperature of the preheating roll is (Tg-40° C.) to (Tg+60° C.), where Tg is fiber Glass transition temperature of the sulfoacylate flakes. 8. The cellulose acylate film according to claim 5, wherein in the stretching step, the longitudinal stretching is performed using nip rolls having a diameter of 3 cm to 50 cm. 9. The cellulose acylate film according to claim 5, wherein in the stretching step, the cellulose acylate sheet is stretched transversely. 10. The cellulose acylate film according to claim 9, wherein in the stretching step, the transverse stretching is performed after the longitudinal stretching. 11. The cellulose acylate film according to claim 9 or 10, characterized in that, in the stretching step, the cellulose acylate sheet is stretched transversely by 1 to 2.5 times with a tenter . 12. The cellulose acylate film according to claim 9, characterized in that, in the stretching step, the transverse stretching is carried out at (Tg) to (Tg+60)°C, where Tg is the glass transition temperature of the cellulose acylate film. 13. A polarizing plate having at least one layer of polarizing film on a substrate, characterized in that the substrate is the cellulose acylate film according to any one of claims 1 to 12. 14. An optical compensation film, characterized in that the cellulose acylate film according to any one of claims 1 to 12 is used as a substrate. 15. An antireflection film, characterized in that the cellulose acylate film according to any one of claims 1 to 12 is used as the substrate. 16. A liquid crystal display device, characterized in that it has: the cellulose acylate film according to any one of claims 1 to 12, or the polarizing plate according to claim 13, or the optical film according to claim 14 A compensation film or the anti-reflection film according to claim 15.

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