JP2003260715A - Method for manufacturing cellulose acylate film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To manufacture a cellulose acylate film with a large optical anisotropy for an electronic displaying material, which is friendly to environment by using a recycled solvent and whose manufacturing cost is lowered and which is excellent in uniformity. <P>SOLUTION: The cellulose acylate film is manufactured by a method comprising processes of dissolving a cellulose acylate into a solvent, casting an obtained cellulose acylate solution on a substrate from a casting die, stripping a formed cellulose acylate film from the substrate, drying a stripped cellulose acylate film to manufacture the cellulose acylate film with specified optical properties, and recovering 80-98 mass% of the solvent vaporized from casting of the solution to drying of the film to feed it as the solvent used in the process for dissolving the cellulose acylate in the solvent. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a cellulose acylate film while reusing a solvent. Particularly, the present invention has a large optical anisotropy, and a cellulose acylate film suitable for an electronic display material,
The present invention relates to a method for manufacturing while reusing a solvent.

[0002]

2. Description of the Related Art A liquid crystal display (LCD) is a CRT (cat
Compared with hode ray tube), it has excellent features such as thinness, light weight, and low power consumption, and is widely used. The most popular method at present is a TN method (Twisted Nematic mode) using a twisted nematic liquid crystal, but there are problems in view angle characteristics and response speed, and many LCD modes have been tried. A reflective liquid crystal display device has also been proposed in terms of power consumption and the like. Currently proposed liquid crystal modes are TN (twisted nematic) and STN (suppert
wisted nematic), VA (vertical aligned), IPS (in
-plane switching), ECB (electrically controlled)
birefringence), FLC (ferroelectric liquid cryst)
al), OCB (optically compensatory bend), HAN
(Hybrid aligned nematic) and ECB (electrically c
ontrolled birefringence) is typical.

Conventionally, many polymers such as cellulose acetate, polyester, polycarbonate and modified polycarbonate are used in the above-mentioned liquid crystal display device. In addition to exhibiting optical anisotropy as a function, it has a substrate for a liquid crystal cell, a protective film for a polarizing plate, and the like. By further combining the above functions, the entire liquid crystal display device can be thinned. It is possible to realize such functions as. inside that,
Cellulose acylate is used quite commonly,
Although it is manufactured by solution casting, recovery of methylene chloride as a solvent is an issue from the viewpoint of environmental preservation and reduction of manufacturing cost. Further, technically, it is technically difficult to completely recover only the solvent, and if the degree of purification is increased, on the contrary, a large amount of cost is required. Cellulose acylate supports for photosensitive materials are manufactured using a recovery solvent, but in electronic display material applications where optical properties (anisotropy) must be precisely controlled,
Problems such as the uniformity in production (no foreign matter) and the severer conditions than the support for the photosensitive material still remained.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to use a recovering solvent, which is environmentally friendly, has a low production cost, and has a high degree of optical anisotropy for an electronic display material having excellent optical anisotropy. To produce a rate film.

[0005]

The object of the present invention has been achieved by the following method for producing a cellulose acylate film. (1) A step of dissolving cellulose acylate in a solvent, a step of casting the obtained cellulose acylate solution on a support through a casting die, a step of peeling the formed cellulose acylate film from the support, and a peeling step. The taken cellulose acylate film is dried and the wavelength is 632.8 nm.
Re retardation value measured at 20 to 250 n
m, a step of producing a cellulose acylate film having an Rth retardation value measured at a wavelength of 632.8 nm in the range of 70 to 400 nm, and 80 to 98% by mass of a solvent vaporized from casting the solution to drying the film.
A method for producing a cellulose acylate film, which comprises a step of recovering and supplying a cellulose acylate as a solvent to be used in a step of dissolving it in a solvent.

The Re retardation value and the Rth retardation value are values defined by the following formulas (I) and (II), respectively: (I) Re = (nx-ny) × d (II) Rth = {(Nx + ny) / 2-nz} × d [where nx is the refractive index in the slow axis direction in the cellulose acylate film plane; ny is the fast axis direction in the cellulose acylate film plane] Is the refractive index of; nz
Is the refractive index in the thickness direction of the cellulose acylate film; and d is the thickness of the cellulose acylate film].

(2) A step of dissolving cellulose acylate in a solvent, a step of casting the obtained cellulose acylate solution on a support through a casting die, and peeling the formed cellulose acylate film from the support. Step, dry the peeled cellulose acylate film,
Re retardation value measured at 50 nm (Re45
0) is 100 to 125 nm, and Re retardation value (Re590) measured at a wavelength of 590 nm is 120 to 16.
0 nm, Re590-Re450 is 2 nm or more, wavelength 5
A step of producing a cellulose acylate film having a (nx-nz) / (nx-ny) value of 1.2 to 2.0 measured at 50 nm, and a solvent vaporized from casting the solution to drying the film. Of 80 to 98% by mass and is supplied as a solvent used in the step of dissolving the cellulose acylate in a solvent.

The value of (nx-nz) / (nx-ny) may be referred to as an Nz factor as defined by the following formula (III): (III) Nz = (nx-nz) / ( nx-ny) [wherein, nx is the refractive index in the slow axis direction in the plane of the cellulose acylate film; ny is the refractive index in the fast axis direction in the plane of the cellulose acylate film; nz
Is the refractive index in the thickness direction of the cellulose acylate film].

(3) The production method according to (1) or (2), wherein the cellulose acylate is cellulose acetate. (4) Cellulose acetate is 55.0 to 61.5
The production method according to (3), which has a acetylation degree of%. (5) In addition to the cellulose acylate, a compound having at least two aromatic rings and a molecular structure that does not hinder the conformation of the two aromatic rings is added to the solvent (1).
Alternatively, the production method according to (2). (6) The production method according to (1) or (2), which produces a film having a thickness of 20 to 60 μm. (7) The production method according to (1) or (2), wherein after the step of drying the film, the step of further stretching the film is carried out. (8) The production method according to (1) or (2), wherein the solvent is recovered by an adsorption recovery method, a condensation recovery method or a combination thereof.

The produced cellulose acylate film can be used in the following optical compensation sheet, circularly polarizing plate or liquid crystal display device. (9) An optical compensatory sheet in which an optically anisotropic layer made of a liquid crystalline compound is provided on the cellulose acylate film produced in (1) above. (10) A linear polarizing film is laminated on the cellulose acylate film produced in (2) above, and the linear polarizing film is arranged so that the slow axis of the cellulose acylate film and the polarizing axis of the linear polarizing film form an angle of 45 °. Circularly polarized plate. (11) A liquid crystal display device having a liquid crystal cell, an optical compensation sheet and a polarizing plate in this order, wherein the optical compensation sheet contains the cellulose acylate film produced in (1) or (2). Liquid crystal display device.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION [Recovery Step] Solvent recovery in solution film formation can be realized by conventionally known methods (adsorption recovery method, condensation recovery method, and both combined methods). The adsorption recovery method collects the gas evaporated in the film forming and drying parts with a duct,
It is sent to an activated carbon adsorption tower and collected by adsorption.
There is a recovery rate of 98% or more. Further, by using desorption with steam together, it is possible to separate into water-insoluble methylene chloride and water-soluble methanol. Although the degree of purification and the operation of the solvent are simple, there is a drawback that the running cost is high. The condensation recovery method collects and condenses the solvent of the film forming machine, and has the advantage that the degree of contamination of the solvent is low and the running cost is low, but the recovery rate is low. An adsorption recovery method is desired from the viewpoint of being environmentally friendly and increasing the recovery rate.

[Cellulose Acylate Film] Cellulose acylate is an ester of cellulose and carboxylic acid. The carboxylic acid is preferably a lower fatty acid. The lower fatty acid means a fatty acid having 6 or less carbon atoms. The number of carbon atoms is preferably 2 (cellulose acetate), 3 (cellulose propionate) or 4 (cellulose butyrate). Mixed fatty acid esters such as cellulose acetate propionate and cellulose acetate butyrate may also be used. Cellulose acetate is particularly preferred. The degree of acetylation of cellulose acetate is preferably 59.0 to 61.5%. The degree of acetylation means the amount of bound acetic acid per unit mass of cellulose. The acetylation degree follows the measurement and calculation of the acetylation degree in ASTM: D-817-91 (test method for cellulose acetate and the like).

The hydroxyls at the 2-, 3- and 6-positions of cellulose are not uniformly substituted, but generally the degree of substitution of the 6-position hydroxyl tends to be small. In the present invention, the substitution degree of the 6-position hydroxyl of cellulose acetate is 2
It is preferable that they are the same or more than the third and third positions. The ratio of the substitution degree at 6-position to the total substitution degree at 2-, 3- and 6-positions is preferably 30 to 40%. The ratio of the 6-position substitution degree is preferably 31% or more, and 32
% Or more is more preferable. The 6th substitution degree is
It is preferably 0.88 or more. In addition to acetyl, the 6-position of cellulose may be substituted with an acyl group having 3 or more carbon atoms (eg, propionyl, butyroyl, valeroyl, benzoyl, acryloyl). The substitution degree at each position can be measured by NMR. The viscosity average degree of polymerization (DP) of cellulose acetate is 25
It is preferably 0 or more, more preferably 290 or more. Further, the polymer film has Mw / Mn (M
It is preferable that the molecular weight distribution of w is a mass average molecular weight and Mn is a number average molecular weight). The specific Mw / Mn value is preferably 1.0 to 1.7, and is 1.3.
Is more preferably from 1.65 to 1.65, most preferably from 1.4 to 1.6.

As cellulose acetate, JP-A-11
No. 5851-Synthesis Example 1 described in paragraphs 0043 to 0044, Synthesis No. 2 described in paragraphs 0048 to 0049, and paragraphs 0051 to 00
The cellulose acetate obtained by the synthesis method of Synthesis Example 3 described in 52 can be used. The materials, various additives, properties, manufacturing methods, etc. of cellulose acetate film are disclosed in JIII Journal of Technical Disclosure
745, March 15, 2001, Institute of Invention).

When used as a transparent support of an optical compensation sheet, the cellulose acylate film preferably has optical anisotropy. The Re retardation value and the Rth retardation value representing the degree of optical anisotropy are defined by the following formulas (I) and (II), respectively. (I) Re = (nx−ny) × d (II) Rth = {(nx + ny) / 2−nz} × d In the formulas (I) and (II), nx is the slow axis direction in the film plane ( The direction in which the refractive index becomes maximum). In the formulas (I) and (II), ny is the refractive index in the fast axis direction (direction in which the refractive index is minimum) in the film plane. In the formula (II), nz is the refractive index in the thickness direction of the film. In formulas (I) and (II), d
Is the film thickness in nm.

The cellulose acylate film used as the transparent support of the optical compensation sheet has a Re retardation value of 20 to 250 nm and an Rth retardation value of 7.
It is in the range of 0 to 400 nm. The Re retardation value is preferably 35 to 200 nm. The Rth retardation value is more preferably in the range of 75 to 300 nm. The birefringence of the transparent support (Δn: nx−
ny) is preferably 0.00025 to 0.0008, and more preferably 0.0004 to 0.0008. The birefringence index {(nx + ny) / 2-nz} in the thickness direction of the transparent support is 0.0008.
It is preferably 8 to 0.005, and 0.0009.
More preferably, it is 5 to 0.0045.

The optical anisotropy of the cellulose acylate film can be controlled by a retardation increasing agent or a stretching treatment. As the retardation increasing agent, an aromatic compound having at least two aromatic rings, such as triazines (triphenyl-1,3,5-triazine, tri-m-tolyl-1,3,5-triazine), trans -1,
4-Cyclohexanedicarboxylic acid diesters (p-
A diester of n-hexylphenol and a diester of pn-amylphenol) can be preferably used. Specific examples of other retardation increasing agents are disclosed in JP-A-20
Nos. 00-111914 and 2000-275434, and PCT / JP00 / 02619.

Two or more kinds of aromatic compounds may be used in combination. The aromatic ring of the aromatic compound includes an aromatic hetero ring in addition to the aromatic hydrocarbon ring. The molecular weight of the retardation increasing agent is preferably 300 to 800. The aromatic compound is used in the range of 0.01 to 20 parts by mass with respect to 100 parts by mass of cellulose acylate. The aromatic compound is preferably used in the range of 0.05 to 15 parts by mass, more preferably 0.1 to 10 parts by mass, based on 100 parts by mass of the cellulose acylate.

The manufacturing method of the present invention is particularly effective when a retardation increasing agent is added to control the optical anisotropy. When a film is produced using a recovery solvent, defects (foreign matter) in the film generally tend to increase. However, in the system in which the retardation increasing agent is added by applying the production method of the present invention, when a film is produced by using a recovery solvent, an unexpected effect that generation of defects (foreign matter) is suppressed occurs. It has been found. A retardation increasing agent can be added mainly for the purpose of suppressing the generation of defects (foreign substances). In that case, the amount added is
It is the same as the addition amount (above) for controlling the optical anisotropy.

When the optical anisotropy of the cellulose acylate film is controlled by the stretching treatment, specifically, the cellulose acylate film may be adjusted in water or water vapor by adjusting the stretching ratio in the longitudinal and lateral directions and further increasing the anisotropy. Means for stretching the rate is effective. In the case of stretching treatment, the angle (slow axis angle) formed by the direction with the largest in-plane refractive index (direction of the slow axis) and the longitudinal direction of the long roll-shaped film (conveying direction) is
It can be controlled by the angle of oblique stretching. The in-plane variation of the slow axis angle is preferably 3 ° or less, more preferably 2 ° or less, and most preferably 1 ° or less with respect to the average value of the slow axis angle. preferable.

Regarding the method of inclining the direction of the slow axis of the polymer film by stretching to a desired angle with respect to the method of conveying the film, JP-A-60-157831, JP-A-2-113920, and JP-A-3-124426. JP-A-3-182701, JP-A-4-164626, and JP-A-2000-9912. For example, in Japanese Unexamined Patent Publication No. 3-182701, a pair of left and right pair of film holding points forming an angle of θ with the running direction is provided at both left and right ears of a continuous film, and each pair of points is θ as the film runs. There has been proposed a method of producing a film having a stretching axis at an arbitrary angle θ with respect to the running direction of the film by a mechanism capable of stretching in the direction.

Further, in Japanese Patent Laid-Open No. 2-113920, the two ends of the film are disposed between two rows of chucks which travel on tenter rails arranged so that the travel distances of the chucks in a predetermined travel section are different. A manufacturing method has been proposed in which the film is stretched in a direction oblique to the length direction of the film by gripping and running. Furthermore, JP 20
JP-A-00-9912 discloses that while a plastic film is uniaxially stretched in the transverse or longitudinal direction, the left and right of the stretching direction are stretched and stretched at different speeds in a longitudinal or transverse direction different from the preceding stretching direction, and the orientation axis is described above. It has been proposed to incline with respect to the uniaxial stretching direction. The draw ratio is 3 to 10
It is preferably 0%. The thickness of the cellulose acylate film is preferably 40 to 140 μm, more preferably 70 to 120 μm.

[Λ / 4 plate] The optical anisotropy characteristic when the cellulose acylate film is used as a λ / 4 plate has a retardation value (R) measured at a wavelength of 450 nm.
e450) is 100 to 125 nm and the wavelength is 5
Retardation value measured at 90 nm (Re590)
Is 120 to 160 nm, and Re590-
The relationship of Re450 ≧ 2 nm is satisfied. Re590-R
More preferably, e450 ≧ 5 nm, and Re5
Most preferably, 90-Re450 ≧ 10 nm. More preferably, the retardation value (Re450) measured at a wavelength of 450 nm is 108 to 120 nm, and the retardation value (R450) measured at a wavelength of 550 nm.
e550) is 125 to 142 nm and has a wavelength of 590
Retardation value (Re590) measured in nm is 1
30 to 152 nm, and Re590-Re
It is preferable to satisfy the relationship of 550 ≧ 2 nm. Re
More preferably, 590-Re550 ≧ 5 nm, and most preferably Re590-Re550 ≧ 10 nm. Also, Re550-Re450 ≧ 10 nm
Is also preferable.

The retardation value (Re) is calculated according to the following formula. Retardation value (Re) = (nx−ny) × d where nx is the in-plane slow axis direction refractive index (maximum in-plane refractive index) of the λ / 4 plate; ny is λ Is the refractive index in the direction perpendicular to the slow axis in the plane of the / 4 plate; and d is
The thickness (nm) of the λ / 4 plate. Furthermore, the λ / 4 plate is
It is preferable to satisfy the following formula. In addition, below, (nx-nz) / (nx-ny) is described as an Nz factor. 1.2 ≦ (nx−nz) / (nx−ny) ≦ 2 In the formula, nx is the refractive index in the in-plane slow axis direction of the λ / 4 plate; ny is the surface of the λ / 4 plate. Is the refractive index in the direction perpendicular to the slow axis inside; and nz is the refractive index in the thickness direction. A particularly preferred range of Nz factor is 1.4 to 1.8, and an even more preferred range is 1.5 to 1.75. The thickness of one cellulose acylate film forming the λ / 4 plate is 5 to 1000 μm.
m is preferable, 10 to 500 μm is more preferable, 30 to 200 μm is further preferable, and 40 to 120 μm is most preferable.

The λ / 4 plate may be prepared by adding a retardation adjusting agent at the time of casting the cellulose acylate film, or by a stretching method for promoting optical anisotropy, or having a wavelength dispersibility on the polymer film. It can be produced by means such as coating and orienting a mixture of a cross compound in which two different kinds of functional groups are orthogonally arranged and a rod-shaped liquid crystal.

[Circular polarizing plate] A λ / 4 plate and a linear polarizing film
A circularly polarizing plate is obtained by laminating so that the angle between the in-plane slow axis of the λ / 4 plate and the polarization axis of the linear polarizing film is substantially 45 °. Substantially 45 ° means 40 to 50 °. The angle between the in-plane slow axis of the λ / 4 plate and the polarization axis of the polarizing film is preferably 41 to 49 °,
It is more preferably 42 to 48 °, and 43 to 4
It is more preferably 7 °, most preferably 44 to 46 °. A transparent protective film is preferably provided on the surface of the linear polarizing film opposite to the λ / 4 plate. A hard coat layer is preferably provided on the transparent protective film. An antireflection layer is preferably provided on the outermost layer.

[Linear Polarizing Film] The linear polarizing film includes an iodine based polarizing film, a dye based polarizing film using a dichroic dye, and a polyene based polarizing film. The iodine type polarizing film and the dye type polarizing film are
Generally, it is manufactured using a polyvinyl alcohol film. The angle formed by the slow axis of the optical compensation sheet and the transmission axis of the linear polarizing film is preferably 3 ° or less, more preferably 2 ° or less, and more preferably 1 ° or less. It is most preferable to arrange as follows.

[Optical Compensation Sheet] The cellulose acylate film having optical anisotropy can be used as an optical compensation sheet. It is also possible to use a cellulose acylate film as a transparent support having optical anisotropy and form an optically anisotropic layer on which the orientation of the discotic liquid crystal is fixed. Regarding the optical compensation sheet having an optically anisotropic layer in which the orientation of the discotic liquid crystal is fixed, JP-A Nos. 9-197397, 9-21144 and 9-
No. 222600, No. 9-230333, No. 9-230
334, 11-212078, 11-3163.
No. 78, No. 11-352328 and the like.

[Alignment Film] The alignment film has a function of defining the alignment direction of the discotic liquid crystal of the optically anisotropic layer.
The alignment film is formed by rubbing an organic compound (preferably a polymer), obliquely depositing an inorganic compound, forming a layer having microgrooves, or an organic compound (eg, ω-tricosanoic acid) by the Langmuir-Blodgett method (LB film). ,
It can be provided by means such as accumulation of dioctadecylmethyl ammonium chloride, methyl stearyl acid). Furthermore, an alignment film which has an alignment function by applying an electric field, a magnetic field, or light irradiation is also known. The alignment film is preferably formed by rubbing a polymer. Polyvinyl alcohol is the preferred polymer. Modified polyvinyl alcohol having a hydrophobic group bonded thereto is particularly preferable. Since the hydrophobic group has an affinity for the discotic liquid crystal of the optically anisotropic layer, the discotic liquid crystal can be uniformly aligned by introducing the hydrophobic group into polyvinyl alcohol. The hydrophobic group is attached to the main chain end or side chain of polyvinyl alcohol. The hydrophobic group is preferably an aliphatic group having 6 or more carbon atoms (preferably an alkyl group or an alkenyl group) or an aromatic group. When a hydrophobic group is bonded to the end of the main chain of polyvinyl alcohol, it is preferable to introduce a linking group between the hydrophobic group and the end of the main chain. Examples of the linking group include -S-,-
^{C (CN) R 1 -,} - NR 2 -, - CS- and a combination thereof. R ¹ and R ² are each a hydrogen atom or an alkyl group having 1 to 6 carbon atoms (preferably an alkyl group having 1 to 6 carbon atoms).
Is.

When a hydrophobic group is introduced into the side chain of polyvinyl alcohol, a part of the acetyl group (--CO--CH ₃ ) of the vinyl acetate unit of polyvinyl alcohol is replaced with an acyl group (-) having 7 or more carbon atoms. CO-R ³⁾ to may be replaced. R ³ is an aliphatic group or aromatic group having 6 or more carbon atoms. A commercially available modified polyvinyl alcohol (eg, MP103, MP203, R1130, manufactured by Kuraray Co., Ltd.) may be used. The saponification degree of the (modified) polyvinyl alcohol used for the alignment film is preferably 80% or more. The degree of polymerization of the (modified) polyvinyl alcohol is preferably 200 or more.

The rubbing treatment is carried out by rubbing the surface of the alignment film with paper or cloth in a certain direction several times. It is preferable to use a cloth in which fibers having uniform length and thickness are uniformly flocked. Usually, the rubbing treatment is performed by rotating a roll around which a commercially available rubbing cloth is wound at a high speed and passing a polymer film having an alignment film above or below the roll. The film transport direction and the roll rotation direction may be the same or opposite. In the optical compensation sheet of the present invention, the direction of the slow axis of the cellulose acylate film and the rubbing are 45
The rubbing roll is orthogonal to the film conveying direction in normal rubbing, but in the present invention, the slow axis direction of the cellulose acylate film is parallel to the film conveying direction. And
It is preferable to incline the rubbing roll at about 45 ° with respect to the film transport direction.

When an alignment film is provided, an undercoat layer (adhesive layer) is preferably provided between the cellulose acylate film and the alignment film. In the case where the polymer film is cellulose triacetate, the adhesive layer is provided by coating the gelatin dispersed in methanol or by saponifying the surface with a saponification solution prepared by dissolving KOH in a solvent containing alkali, especially IPA. It is preferable.

[Optically Anisotropic Layer] The optically anisotropic layer is formed of a discotic liquid crystalline compound. The discotic liquid crystal compound generally has optically negative uniaxiality. In the optical compensatory sheet, the discotic liquid crystal compound preferably has an angle formed by the disc surface and the cellulose acylate film surface that changes in the depth direction of the optically anisotropic layer (hybrid alignment). In addition, it is preferable that the optically anisotropic layer does not have a direction in which the retardation value becomes 0 or an optical axis. The optically anisotropic layer is preferably formed by aligning the discotic liquid crystalline compound with the above alignment film and fixing the discotic liquid crystalline compound in the aligned state. The discotic liquid crystalline compound is preferably fixed by a polymerization reaction. The thickness of the optically anisotropic layer is 0.
The thickness is preferably 5 to 100 μm, and 0.5 to 3
More preferably 0 μm

[Discotic Liquid Crystalline Compound] Regarding the discotic liquid crystalline compound, various documents (C. De.
strade et al., Mol. Crysr. Liq. Cryst., vol. 71, pa
ge 111 (1981); Chemical Society of Japan, Quarterly Chemistry Review, No.
22, Liquid Crystal Chemistry, Chapter 5, Chapter 10, Section 2 (199
4); B. Kohne et al., Angew. Chem. Soc. Chem. Com
m., page 1794 (1985); J. Zhang et al., J. Am. Che
m. Soc., vol. 116, page 2655 (1994)). The polymerization of the discotic liquid crystalline compound is described in JP-A-8-27284. In order to fix the discotic liquid crystal compound by polymerization, a polymerizable group as a substituent is bonded to the discotic core of the discotic liquid crystal compound, and after alignment, it is crosslinked and immobilized by thermal polymerization or photopolymerization. Is preferred. However, when the polymerizable group is directly bonded to the discotic core, it becomes difficult to maintain the alignment state in the polymerization reaction. Therefore, it is preferable to introduce a linking group between the discotic core and the polymerizable group.

Examples of the photopolymerization initiator which causes a polymerization reaction for fixing the oriented discotic liquid crystal compound while maintaining the alignment state include α-carbonyl compounds (US Pat. Nos. 2,367,661 and 2,367,670). Descriptions in each specification), Acyloin ether (US Pat. No. 2,448,828)
Specification), α-hydrocarbon-substituted aromatic acyloin compound (described in US Pat. No. 2,722,512), polynuclear quinone compound (US Pat. Nos. 3,046,127 and 29517).
58), combinations of triarylimidazole dimers and p-aminophenyl ketones (described in US Pat. No. 3,549,367), acridine and phenazine compounds (JP-A-60-105667, US Pat. No. 4,239,850). Specification description) and an oxadiazole compound (described in US Pat. No. 4,212,970). The amount of the photopolymerization initiator used is preferably 0.01 to 20% by mass of the solid content of the coating liquid, and more preferably 0.5 to 5% by mass.
Light irradiation for the polymerization of discotic liquid crystalline molecules
It is preferable to use ultraviolet rays. Irradiation energy is 2
It is preferably 0 to 5000 mJ / cm ² and 1
More preferably, it is from 00 to 800 mJ / cm ² . Further, in order to accelerate the photopolymerization reaction, light irradiation may be carried out under heating conditions. A protective layer may be provided on the optically anisotropic layer.

[Liquid Crystal Display Device] The present invention is effective in any of transmissive, reflective and semi-transmissive liquid crystal display devices. The display mode of the liquid crystal cell is OCB (optically compe
nsatory bend), HAN (hybrid aligned nematic), T
N (twisted nematic), STN (supper twisted nemati
c), VA (vertical aligned), IPS (in-plane switch)
ing), ECB (electrically controlled birefringenc
Either e) or FLC (ferroelectric liquid crystal) mode may be used. In particular, OCB, HAN, TN,
And ECB mode are preferred.

A liquid crystal cell in which a nematic liquid crystal exhibiting a bend alignment or a hybrid alignment is sealed, and an OCB type or HAN type liquid crystal display device using the same,
For the principle, US Pat. No. 3,118,197,
Details are disclosed in Japanese Patent No. 3118197. The liquid crystal display device of the present invention can be used in a normally white mode in which bright display is performed when the applied voltage is low and dark display when the applied voltage is high, and in a normally black mode in which dark display is applied when the applied voltage is low and bright display is applied when the applied voltage is high. it can. Regarding the driving method of the transmissive, reflective and semi-transmissive liquid crystal display device of the present invention, the active matrix method is preferable to the simple matrix method, and the TFT (Thin Film Transistor)
tor), TFD (Thin Film Diode) or MIM (Metal I
nsulatorMetal) is more preferable. More preferably, low temperature polysilicon or continuous grain boundary silicon is used for the TFT.

For details, refer to "Liquid Crystal Device Handbook" edited by Japan Society for the Promotion of Science, 142th Committee, Nikkan Kogyo Shimbun, "Liquid Crystal Application" by Koji Okano, Baifukan, "Color Liquid Crystal Display" by Shunsuke Kobayashi, industrial books, etc. "Next-generation liquid crystal display technology" Tatsuo Uchida, Industrial Research Committee, "Cutting-edge of liquid crystal display" edited by Young Researchers of Liquid Crystal, Sigma Publishing,
"Liquid crystal: Basics and new applications of LCD" In the case of a transmissive liquid crystal display device described in "Liquid Crystal Young Research Group", Sigma Publishing, etc., it can be constructed in the following order, for example.

[0039] ──────────────────────────────────── 9. Anti-reflection film 8. Linear polarizing film 7. Optical compensation sheet     73. Biaxial transparent support (cellulose acylate film according to the present invention)     72. Alignment film     71. Optically anisotropic layer with fixed orientation of discotic liquid crystal 6. Adhesive layer 5. Liquid crystal cell     57. Upper glass substrate     56. Upper transparent electrode layer     55. Upper alignment film     54. Liquid crystal layer     53. Lower alignment film     52. Lower transparent electrode layer     51. Lower glass substrate 4. Adhesive layer 3. Optical compensation sheet     33. Optically anisotropic layer with fixed orientation of discotic liquid crystal     32. Alignment film     31. Biaxial transparent support (cellulose acylate film according to the present invention) 2. Linear polarizing film 1. Transparent protective film (cellulose triacetate film) 0. Backlight ────────────────────────────────────

In the case of color display, a color filter layer can be further provided. The color filter layers are preferably provided above and below the liquid crystal cell (5) adjacent to each other. In the case of a reflective liquid crystal display device, for example, it can be constructed in the following order.

[0041] ──────────────────────────────────── 4. Anti-reflection film 3. Linear polarizing film 2. λ / 4 plate (cellulose acylate film according to the present invention) 1. Liquid crystal cell     17. Upper glass substrate     16. Upper transparent electrode layer     15. Upper alignment film     14. Liquid crystal layer     13. Lower alignment film     12. Lower transparent electrode layer     11. Lower glass substrate 0. a reflector ────────────────────────────────────

In the case of color display, a color filter layer can be further provided. The color filter layers are preferably provided above and below the liquid crystal cell 1. A reflective electrode may be attached instead of the reflective plate (0). Further, in order to increase the brightness of the image, the reflectance of the reflection plate may be reduced and a backlight may be used. If the surface of the reflector is smooth, only the specular reflection component may be reflected and the viewing angle may be narrowed. Therefore, it is preferable to introduce an uneven structure (described in JP-A-07-333606) on the surface of the reflection plate. When the surface of the reflection plate is flat (instead of introducing an uneven structure on the surface), a light diffusion film may be attached to one side (cell side or outside) of the polarizing film.

[0043]

EXAMPLES Reference Example 1 (Preparation of Cellulose Acetate Solution) The following composition was put into a mixing tank and stirred while heating to dissolve each component to prepare a cellulose acetate solution.

[0044] ────────────────────────────────────   Cellulose acetate solution composition ────────────────────────────────────   100 parts by mass of cellulose acetate having an acetylation degree of 61.1%   Triphenyl phosphate (plasticizer) 7.0 parts by mass   Biphenyl diphenyl phosphate (plasticizer) 3.4 parts by mass   Methylene chloride (first solvent) 350 parts by mass   Methanol (second solvent) 35 parts by mass ────────────────────────────────────

(Preparation of Retardation Raising Agent Solution) Into another mixing tank, 15 parts by mass of a retardation increasing agent (Sumisolv TM165-F, manufactured by Sumitomo Chemical Co., Ltd.), 75 parts by mass of methylene chloride and 15 parts by mass of methanol were charged. Stirring was performed while heating to prepare a retardation increasing agent solution.

(Preparation of Cellulose Acetate Film)
A dope was prepared by mixing 50 parts by mass of the retardation increasing agent solution with 495 parts by mass of the cellulose acetate solution and stirring the mixture. The addition amount of the retardation increasing agent was 7 parts by mass with respect to 100 parts by mass of cellulose acetate. The obtained dope was cast using a band casting machine. The film having a residual solvent amount of 50% by mass was peeled from the band, and the film having a residual solvent amount of 37% by mass was laterally stretched at a stretching ratio of 17% using a tenter under the condition of 130 ° C. to obtain a width after stretching. It was kept as it was at 120 ° C. for 30 seconds. Then, the clip was removed to produce a cellulose acetate film (width 800 mm, thickness 60 μm).

[Example 1] In the process of preparing the cellulose acetate film of Reference Example 1, the amount of residual solvent in the film cast on the support band, dried by hot air and peeled off was 10% by weight based on the dry amount. The dry exhaust gas up to was condensed and collected at -5 ° C. The dry exhaust gas generated in the subsequent drying zone is recovered by the activated carbon adsorption layer, the recovered solvent is dehydrated and separated by distillation, and a mixed solvent of methylene chloride and methanol (mass ratio: methylene chloride / methanol = 9).
2/8) was obtained. A cellulose acetate film was produced in the same manner as in Reference Example 1, except that the obtained mixed solvent was used as methylene chloride (first solvent) and methanol (second solvent) in the preparation of the cellulose acetate solution of Reference Example 1. did. The film thickness is 59 μm
Met.

Reference Example 2 The cellulose acetate solution was used as it was (without mixing the retardation increasing agent solution) as a dope. The dope was heated to 50 ° C. and cast on a mirror-like stainless steel casting support through a casting gaze.
Casting support temperature is 10 ℃, casting speed is 40m
The coating width was 80 cm / min. Drying at 120 ℃
Was blown with dry air. After 2 minutes, it was peeled from the casting support made of mirror-finished stainless steel, and then dried at 110 ° C. for 10 minutes and further at 150 ° C. for 30 minutes to obtain a cellulose acetate film (film thickness 60 μm).

[Comparative Example 1] In the process of preparing the cellulose acetate film of Reference Example 2, the amount of residual solvent in the film cast on the support band, dried by hot air and peeled off was 10% by weight based on the dry amount. The dry exhaust gas up to was condensed and collected at -5 ° C. The dry exhaust gas generated in the subsequent drying zone is recovered by the activated carbon adsorption layer, the recovered solvent is dehydrated and separated by distillation, and a mixed solvent of methylene chloride and methanol (mass ratio: methylene chloride / methanol = 9).
2/8) was obtained. A cellulose acetate film was produced in the same manner as in Reference Example 2, except that the obtained mixed solvent was used as methylene chloride (first solvent) and methanol (second solvent) in the preparation of the cellulose acetate solution of Reference Example 2. did.

(Evaluation of Cellulose Acetate Film)
Defects (recognized as foreign matter) were investigated when the cellulose acetate films produced in Reference Examples 1 and 2, Example 1 and Comparative Example 1 were continuously produced with a length of 200 m. First result
Shown in the table.

(Measurement of Optical Properties) With respect to the produced cellulose acetate film, an ellipsometer (M-1
50, manufactured by JASCO Corporation, wavelength 632.8 nm
The Re retardation value (Re) and the Rth retardation value (Rth) were measured. Each measurement was performed at 10 points at equal intervals in the width direction, and an average value was obtained. The results are shown in Table 1. For Re, the standard deviation was calculated and shown as the width (±).

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[Table 1] Table 1 ──────────────────────────────────── Film retardation manufacturing method Solvent increase Agent Re Rth Foreign substance ──────────────────────────────────── Example 1 Recovery addition 40 ± 0.7 nm 171 nm 0 piece Reference example 1 New addition 38 ± 1.0 nm 170 nm 1 piece Comparative example 1 No recovery 7 ± 2.0 nm 25 nm 3 pieces Reference example 2 No new 7 ± 0.9 nm 25 nm 1 piece ──────── ────────────────────────────

[Reference Example 3] (Preparation of λ / 4 plate) At room temperature, the average degree of acetylation was 60.1.
% Cellulose triacetate 120 parts by mass, triphenyl phosphate 9.4 parts by mass, biphenyl diphenyl phosphate 4.8 parts by mass, 4-n-heptylphenol diester of trans-1,4-cyclohexanedicarboxylic acid as a retardation increasing agent 1. 00 parts by mass, methylene chloride 544 parts by mass, methanol 99
A part (mass part) and 20 parts by mass of n-butanol were mixed and dissolved to prepare a solution (dope). The obtained dope was cast on a moving stainless steel band and dried by passing through a 25 ° C. zone for 1 minute and a 45 ° C. zone for 5 minutes. The residual amount of solvent after drying was 30% by mass. After that, the film was peeled from the band, the winding speed was made higher than the carrying speed of the band, and the film was stretched in the carrying direction at 130 ° C. The direction perpendicular to the stretching direction was allowed to shrink freely. After stretching, it was dried by passing through a zone at 120 ° C. for 30 minutes, and the stretched film was wound up to prepare a cellulose acetate film (λ / 4 plate). The residual amount of solvent after stretching was 0.1% by mass. The thickness of the film thus obtained was 102 μm.

Example 2 (Production of λ / 4 Plate) The solvents (methylene chloride, methanol and n-butanol) used in Reference Example 3 were recovered in the same manner as in Example 1. A cellulose acetate film (λ / 4 plate) was produced in the same manner as in Reference Example 3 except that the recovered solvent was used.

(Evaluation of Cellulose Acetate Film)
The obtained cellulose acetate film (λ / 4 plate) was measured for retardation value (Re) at wavelengths of 450 nm, 550 nm and 590 nm using an ellipsometer (M-150, manufactured by JASCO Corporation). Furthermore, from the measurement of the refractive index by the Abbe refractometer and the measurement of the angle dependence of the retardation, the wavelength 5
The refractive index nx in the in-plane slow axis direction at 50 nm, the refractive index ny in the direction perpendicular to the in-plane slow axis, and the refractive index nz in the thickness direction are calculated to obtain (nx-nz) / (nx-ny) The value was calculated. The above results are shown in Table 2.

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[Table 2]                                 Table 2 ──────────────────────────────────── Film Re450 Re550 Re590 Re590-Re450 Manufacturing method Solvent (nm) (nm) (nm) (nm) Nz ──────────────────────────────────── Example 2 Recovery 122.0 137.4 143.0 21.0 1.61 Reference Example 3 New 123.3 137.2 144.8 21.5 1.60 ────────────────────────────────────

Example 3 (Saponification Treatment of Cellulose Acetate Film) The cellulose acetate film prepared in Example 1 was mixed with 1.5
It was immersed in a specified aqueous sodium hydroxide solution at 55 ° C. for 2 minutes. It was washed in a water-washing bath at room temperature and neutralized at 30 ° C. with 0.1 N sulfuric acid. It was washed again in a water-washing bath at room temperature, and dried with warm air at 100 ° C. In this way, the surface of the cellulose acetate film was saponified.

(Formation of Alignment Film) A coating solution having the following composition was applied to one surface of a saponified cellulose acetate film (transparent support) using a # 14 wire bar coater.
4 ml / m ^{2 was} applied. It was dried with hot air of 60 ° C. for 60 seconds and further with hot air of 90 ° C. for 150 seconds. Next, rubbing treatment was performed in the direction of 45 ° with respect to the stretching direction of the cellulose acetate film B (transparent support) (substantially coincident with the slow axis) to form an alignment film.

[0059] ────────────────────────────────────   Alignment film coating liquid composition ────────────────────────────────────   30 parts by mass of the following modified polyvinyl alcohol   Water 390 parts by mass   115 parts by mass of methanol   Glutaraldehyde (crosslinking agent) 2.5 parts by mass ────────────────────────────────────

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[Chemical 1]

(Formation of Optically Anisotropic Layer) The following coating solution was coated on the rubbing-treated surface of the alignment film with a # 3 wire bar. This was attached to a metal frame and heated in a constant temperature bath at 130 ° C. for 2 minutes to align the discotic liquid crystal molecules. Next, UV irradiation was performed for 1 minute at 130 ° C. using a 120 W / cm high pressure mercury lamp to polymerize the discotic liquid crystal molecules. Then, it stood to cool to room temperature. In this way, an optically anisotropic layer was formed and an optical compensation sheet was produced.

[0062] ────────────────────────────────────   Composition of coating liquid for optically anisotropic layer ────────────────────────────────────   42 parts by mass of the following discotic liquid crystal molecule   Ethylene oxide modified trimethylolpropane triacrylate (V # 36 0, Osaka Organic Chemical Co., Ltd.) 5 parts by mass   Cellulose acetate butyrate (CAB551-0.2, Eastman Chemi Made by Cal) 1 part by mass   Cellulose acetate butyrate (CAB531-1, Eastman Chemical (Made by company) 0.2 parts by mass   Photopolymerization initiator (Irgacure-907, manufactured by Ciba Geigy) 1.5 parts by mass   Sensitizer (Kayacure-DETX, manufactured by Nippon Kayaku Co., Ltd.) 0.5 part by mass   Methyl ethyl ketone 100 parts by mass ────────────────────────────────────

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[Chemical 2]

For the produced optical compensation sheet, an ellipsometer (M-150, manufactured by JASCO Corporation) was used.
Re (0 °), Re (40
°) and Re (-40 °) were measured. The results are shown below. Re (0 °): 38 nm Re (40 °): 126 nm Re (-40 °): 44 nm

(Preparation of Elliptical Polarizing Plate) Iodine was adsorbed on a stretched polyvinyl alcohol film to prepare a linear polarizing film. Next, the transparent support side of the produced optical compensation sheet was attached to one side of the linear polarizing film A using a polyvinyl alcohol adhesive. The slow axis of the transparent support and the transmission axis of the linear polarizing film were arranged in parallel. As a result, the angle formed by the direction of the slow axis of the transparent support and the transmission axis of the linear polarizing film was 0.3 °. Then, a commercially available cellulose triacetate film (Fujitac TD80UF, manufactured by Fuji Photo Film Co., Ltd.) was saponified in the same manner as above, and the saponified surface was opposite to the linear polarizing film using an acrylic adhesive and a urethane adhesive. It was pasted on (the side to which the optical compensation sheet was not pasted). In this way, an elliptically polarizing plate was produced.

(Production of Bend Alignment Liquid Crystal Cell) A polyimide film was provided as an alignment film on a glass substrate having an ITO electrode, and the alignment film was rubbed. The two glass substrates obtained were opposed to each other in such a manner that the rubbing directions were parallel to each other, and the cell gap was set to 6 μm. A liquid crystal compound having Δn of 0.1396 in the cell gap (ZLI1132,
(Produced by Merck & Co., Inc.) was injected to prepare a bend alignment liquid crystal cell.

(Production of Liquid Crystal Display Device) Two elliptically polarizing plates were attached so as to sandwich the produced bend alignment cell. A liquid crystal display device was manufactured by disposing the elliptically polarizing plate so that the optically anisotropic layer faces the cell substrate and the rubbing direction of the liquid crystal cell and the rubbing direction of the optically anisotropic layer facing the liquid crystal cell are antiparallel.

Reference Example 4 Example 3 was repeated except that the cellulose acetate film prepared in Example 1 was used in place of the cellulose acetate film prepared in Example 1.
A liquid crystal display device was produced in the same manner as in.

Comparative Example 2 Example 3 was repeated except that the cellulose acetate film produced in Comparative Example 1 was used instead of the cellulose acetate film produced in Example 1.
A liquid crystal display device was produced in the same manner as in.

Reference Example 5 Example 3 was repeated except that the cellulose acetate film produced in Reference Example 2 was used in place of the cellulose acetate film produced in Example 1.
A liquid crystal display device was produced in the same manner as in.

(Evaluation of Liquid Crystal Display Device) A white display voltage of 1.8 V and a black display voltage of 5.8 V were applied to the liquid crystal cell of the manufactured liquid crystal display device, and a measuring instrument (EZ-Contrast) was used.
160D, manufactured by ELDIM), using black display (L1)
From 8 to white display (L8), the viewing angle was measured.
The angle at which the contrast ratio is 10 or more and there is no grayscale inversion on the black side is the viewing angle. The results are shown in Table 3. Furthermore, the screen when the liquid crystal display device is displayed in black (21.5 cm × 28.
The spot-like white spots (hereinafter referred to as bright spot defects) in 5 cm) due to leakage of light were visually evaluated, and the results (number) are also shown in Table 3.

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[Table 3] Table 3 ──────────────────────────────────── Liquid crystal film Ascending viewing angle luminance defect Display device manufacturing method Solvent agent Left Right Up Bottom Bottom Number ──────────────────────────────────── Example 3 Example 1 Recovery Addition 80 ° 80 ° 80 ° 73 ° 0 pcs Reference Example 4 Reference Example 1 New addition 80 ° 80 ° 79 ° 72 ° 1 pcs Comparative Example 2 Comparative Example 1 No recovery 72 ° 72 ° 69 ° 45 ° 3 Reference example 5 Reference example 2 New None 72 ° 71 ° 69 ° 46 ° 1 piece ──────────────────────────────── ─────

Example 4 A cellulose acetate film was prepared in the same manner as in Comparative Example 1 except that the thickness was changed to 40 μm. 210 g of a heat-crosslinkable fluoropolymer (JN-7228, solid content concentration 6%, manufactured by JSR Corporation) on a cellulose acetate film, with an average particle size of 1
0 to 20 nm, silica sol with a solid content concentration of 30% by mass (M
EK-ST, Nissan Chemical Co., Ltd. 18g, and MEK
After adding 200 g and stirring, the coating liquid for low refractive index layer filtered with a polypropylene filter having a pore size of 1 μm was applied with a bar coater, dried at 80 ° C. for 5 minutes, and then heated at 120 ° C. for 10 minutes to crosslink the polymer. Then, a low-refractive index layer having a thickness of 0.1 μm was formed to prepare an antireflection film. Example 3
A liquid crystal display device was produced in the same manner as in the production of the liquid crystal display device, except that the protective film attached to the polarizing plate was changed to the antireflection protective film produced above. After confirming the image displayed on the manufactured device,
In addition to widening the viewing angle and improving bright spot defects, it was confirmed that the front contrast was improved by antireflection.

Example 5 (Production of linearly polarizing film) Polyvinyl alcohol (PVA)
Iodine 2.0 g / l, potassium iodide 4.0
It was immersed in an aqueous solution of g / l at 25 ° C. for 240 seconds and further immersed in an aqueous solution of 10 g / l of boric acid at 25 ° C. for 60 seconds, then introduced into a tenter stretching machine and stretched 5.3 times to give a tenter. After bending in the stretching direction, keeping the width constant thereafter, and drying in an atmosphere of 80 ° C. while shrinking, the film was separated from the tenter and wound up. The water content of the PVA film before the start of stretching was 31%, and the water content after drying was 1.5%. The difference in transport speed between the left and right tenter clips was less than 0.05%, and the angle between the center line of the film introduced and the center line of the film sent to the next step was 46 °. No wrinkles or film deformation was observed at the tenter exit. The absorption axis direction of the obtained linear polarizing film was inclined by 45 ° with respect to the transport direction (longitudinal direction) of the tenter, and the transmittance of this linear polarizing film at 550 nm was 43.7% and the polarization degree was 99.97%. It was

(Preparation of Circular Polarizing Plate) The antireflection film prepared in Example 4 and the λ / 4 plate (cellulose acetate film) prepared in Example 2 were mixed at 55 ° C. with 1.5 NNaO.
After dipping in H aqueous solution for 1 minute to saponify both sides, thoroughly wash with dilute sulfuric acid and water, and dry, apply polyvinyl alcohol adhesive to each side to a thickness of about 30μ, and roll on both sides of the linear polarizing film. The pieces were laminated with a two-roll and dried at 80 ° C. to prepare a circularly polarizing plate. The film thickness of this circularly polarizing plate was about 227 μm.

(Preparation of HAN-type liquid crystal cell) A glass film having an ITO electrode was provided with a polyimide film as an alignment film and subjected to rubbing treatment. Another glass substrate with an ITO electrode was prepared, and a SiO vapor deposition film was provided as an alignment film. The two glass substrates are arranged so that the alignment films face each other, and are bonded with a cell gap of 5 μm.
I1132 (Δn = 0.1396) was injected to fabricate a HAN type liquid crystal cell. The retardation (Re2) of the liquid crystal layer of the obtained liquid crystal cell is 698 nm.

(Fabrication of HAN Alignment Mode Reflective Liquid Crystal Display Device) A HAN type liquid crystal cell was attached to a reflector used in a commercially available reflective liquid crystal display device, and an optical compensation sheet was placed on the liquid crystal cell. So that the rubbing direction of the optical compensation sheet and the rubbing direction of the optical compensation sheet are anti-parallel to each other by attaching an acrylic pressure-sensitive adhesive to the cellulose triacetate side of the optical compensation sheet, and further laminating the λ / Acrylic adhesive is applied to the 4 plate side, and
The / 4 plate was laminated so that the slow axis was parallel to the rubbing direction of the liquid crystal cell, to prepare a HAN alignment mode liquid crystal display device.

Reference Example 6 HAN alignment mode reflection was performed in the same manner as in Example 7 except that the λ / 4 plate produced in Reference Example 3 was used in place of the λ / 4 plate produced in Example 2. Type liquid crystal display device was produced.

(Evaluation of Liquid Crystal Display Device) In the liquid crystal cell of the liquid crystal display device manufactured in Example 5 and Reference Example 6, 1 kHz was used.
The rectangular wave voltage of 2 V was applied with a white display voltage of 2 V and a black display voltage of 6 V, and the front contrast ratio was measured using a measuring instrument (EZ-Contrast 160D, manufactured by ELDIM). Furthermore, the viewing angle (angle range where the contrast ratio is 5 or more) in the left-right direction (direction orthogonal to the rubbing direction of the cell) was examined. The liquid crystal display device of Example 5 had a contrast ratio from the front of 25, and the viewing angle at which the contrast ratio was 2 was 120 ° or more in the vertical direction and 120 ° or more in the horizontal direction, which were favorable results. Further, it was confirmed that neutral gray was displayed with no color in both white display and black display. Reference example 6
The contrast and color of the liquid crystal display device of No. 2 were at the same level as in Example 5.

[Example 6] Instead of the cellulose acetate of Example 1, the cellulose sialate (1
-A-C to 36-A-C) Example 1
It was made in the same way as. Each cellulose acylate is disclosed in JIII Journal of Technical Disclosure No. 2000-1745 (March 15, 2001).
It was prepared by the method described in (Japanese). Evaluation was also performed by the same method as in Example 1, and the same effect as that of the present invention was confirmed.

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[Table 4]

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G02F 1/13363 G02F 1/13363 // B29K 1:00 B29K 1:00 B29L 7:00 B29L 7:00 F Term (reference) 2H049 BA02 BA03 BA06 BA07 BA27 BA42 BB03 BB18 BB33 BB49 BC01 BC09 BC22 2H091 FA08X FA08Z FA11X FA11Z FA37X GA01 GA06 GA16 LA12 LA18 4F205 AA01 AC05 GA07 GB02 GC07 GN22 GN24 GN29 GW21 GW45

Claims (2)

[Claims] 1. A step of dissolving cellulose acylate in a solvent, a step of casting the obtained cellulose acylate solution on a support through a casting die, and a step of peeling the formed cellulose acylate film from the support. Then, the stripped cellulose acylate film is dried to give a wavelength of 63
Re retardation value measured at 2.8 nm is 20 to
The step of producing a cellulose acylate film having an Rth retardation value measured at 250 nm and a wavelength of 632.8 nm in the range of 70 to 400 nm, and the vaporized solvent from 80 to 9 from the casting of the solution to the drying of the film.
A method for producing a cellulose acylate film, which comprises a step of recovering 8% by mass and supplying it as a solvent to be used in a step of dissolving a cellulose acylate in a solvent. 2. A step of dissolving cellulose acylate in a solvent, a step of casting the obtained cellulose acylate solution on a support through a casting die, and a step of peeling the formed cellulose acylate film from the support. Then, the peeled cellulose acylate film is dried to a wavelength of 450
Re retardation value (Re450) measured in nm
Re measured at 100 to 125 nm and a wavelength of 590 nm
Retardation value (Re590) is 120 to 160n
m, Re590-Re450 is 2 nm or more, wavelength 550
(nx-nz) / (nx-ny) value measured in nm is 1.2 to 2.0, and a step of producing a cellulose acylate film, and a solvent vaporized from casting the solution to drying the film. Of 80 to 98% by mass and is supplied as a solvent used in the step of dissolving the cellulose acylate in a solvent.