JP2002131537A - Phase difference plate, circularly polarizing plate, and reflection type liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a phase difference plate which generates λ/4 or λ/2 phase difference in the whole visible ray region by one sheet of a polymer film and which is improved in the adhesion property. SOLUTION: The phase difference plate consists of one sheet of a polymer film which shows the retardation (Re450) measured at 450 nm wavelength ranging from 100 to 125 nm and the retardation (Re590) measured at 590 nm wavelength ranging from 120 to 160 nm an satisfies the relation of Re590-Re450>=2 nm. The one surface or both surfaces of the polymer film are subjected to surface treatment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a retardation plate having an optically anisotropic layer, a circularly polarizing plate using the retardation plate, and a reflection type liquid crystal display device. In particular, the present invention relates to a λ / 4 plate or a λ / 2 plate used in a liquid crystal display device, a λ / 4 plate used for a pickup for writing on an optical disk, or a λ / 4 plate used as an antireflection film. It relates to an effective retardation plate.

[0002]

2. Description of the Related Art A λ / 4 plate and a λ / 2 plate have many uses related to an antireflection film and a liquid crystal display device, and have already been actually used. However, λ / 4 plate or λ
Λ / 4 or λ / 2 at a specific wavelength
Most of those who achieved were. JP-A-5-27
Nos. 118 and 5-27119 disclose a retardation plate in which a birefringent film having a large retardation and a birefringent film having a small retardation are laminated so that their optical axes are orthogonal to each other. Is disclosed.
If the difference in retardation between the two films is λ / 4 or λ / 2 over the entire visible light range, the retardation plate theoretically has a λ / 4 plate or λ /
Functions as two plates. Japanese Patent Application Laid-Open No. 10-68816 discloses a polymer film having a wavelength of λ / 2 at a specific wavelength and a polymer film made of the same material as that of the polymer film.
There is disclosed a retardation plate capable of obtaining λ / 4 in a wide wavelength region by laminating a polymer film of No. 2 with a polymer film. Japanese Patent Application Laid-Open No. Hei 10-90521 also discloses that laminating two polymer films makes it possible to obtain λ / 4 in a wide wavelength region.
Is disclosed. As the above polymer film, a stretched film of a synthetic polymer such as polycarbonate has been used.

[0003] Japanese Patent Application Laid-Open No. 2000-137116 discloses a broadband λ / 4 plate using one polymer film. However, when this λ / 4 plate is used for a reflection type liquid crystal display device, although the contrast is slightly improved, the effect is not sufficient.

The reflection type liquid crystal display device is used as a display of a portable device such as a portable information terminal, a portable game machine or a portable telephone, because a backlight is not required and the power consumption is small. The reflection type liquid crystal display device has a basic structure in which a reflection plate, a liquid crystal cell and a polarizing film are laminated in this order. Regarding the display mode of the liquid crystal cell, TN (Tw
isted Nematic), STN (Supper Twisted Nemati)
c), HAN (Hybrid Aligned Nematic), HPDLC
(Holographic Polymer Dispersed Liquid Crystal),
Various display modes such as GH (Guest Host) have been proposed. TN mode reflective liquid crystal display devices have already been put to practical use. In a transmission type liquid crystal display device, two polarizing films are indispensable.
By using a / 4 plate, an image can be displayed even with a single polarizing film. When one polarizing film is reduced, light is not attenuated, and a bright image can be displayed. A reflection type liquid crystal display device having a λ / 4 plate is disclosed in JP-A-10-1863.
No. 57 describes this.

[0005]

When used as a mobile device such as a mobile phone or an information portable terminal, the reflection type liquid crystal display device is exposed to a severe environment. For example, the interior of a car whose windows are closed in summer can be quite hot. In some areas, winter temperatures are quite low.
When exposed to such a severe environment, a problem that the retardation plate is peeled off from the polarizing plate or the substrate easily occurs. An object of the present invention is to provide a retardation plate which achieves λ / 4 or λ / 2 over the entire visible light range and has improved adhesion with one polymer film. Another object of the present invention is to provide a retardation plate and a liquid crystal display device having excellent durability even in a severe use environment.

[0006]

The object of the present invention is to provide a retardation plate (λ / 4 plate) of the following (1) to (4), a circularly polarizing plate of the following (5), and a reflection type of the following (6). A liquid crystal display device was achieved by the following retardation plate (λ / 2 plate) (7) to (8). (1) a retardation value (Re450) measured at a wavelength of 450 nm is in the range of 100 to 125 nm,
And a retardation value (R
e590) is in the range of 120 to 160 nm, and is made of one polymer film satisfying the relationship of Re590-Re450 ≧ 2 nm, and one or both surfaces of the polymer film are surface-treated. Retarder. (2) a retardation value (Re450) measured at a wavelength of 450 nm is in the range of 108 to 120 nm,
The retardation value (Re5) measured at a wavelength of 550 nm
50) is in the range of 125 to 142 nm and the wavelength 59
The retardation value (Re590) measured at 0 nm is in the range of 130 to 152 nm and
The retardation plate according to (1), which satisfies the relationship of -Re550 ≧ 2 nm.

(3) The retardation plate according to (1), wherein the polymer film comprises a cellulose ester film, and the cellulose ester film contains a compound having at least two aromatic rings. (4) The polymer film has a refractive index nx in the in-plane slow axis direction, a refractive index ny in a direction perpendicular to the in-plane slow axis, and a refractive index nz in the thickness direction of 1 ≦ (nx−nz). ) /
The retardation plate according to (1), comprising a cellulose ester film satisfying the relationship of (nx-ny) ≦ 2.

(5) The phase difference plate and the linear polarizing film are laminated so that the angle between the slow axis in the plane of the phase difference plate and the transmission axis of the linear polarizing film is substantially 45 °. A circularly polarizing plate, wherein the retardation plate has a retardation value (Re450) measured at a wavelength of 450 nm in a range of 100 to 125 nm, and a retardation value (Re590) measured at a wavelength of 590 nm in a range of 120 to 160 nm. Yes,
A circularly polarizing plate comprising a single polymer film satisfying the relationship of Re590-Re450 ≧ 2 nm, wherein one or both surfaces of the polymer film are subjected to a surface treatment. (6) A reflective liquid crystal display device using the retardation plate according to (1).

(7) The retardation value (Re450) measured at a wavelength of 450 nm is in the range of 200 to 250 nm, the retardation value (Re590) measured at a wavelength of 590 nm is in the range of 240 to 320 nm, and Re590 -A retardation plate comprising a single polymer film satisfying a relationship of Re450 ≥ 2 nm, wherein one or both surfaces of the polymer film are subjected to a surface treatment. (8) a retardation value (Re450) measured at a wavelength of 450 nm is in a range of 216 to 240 nm,
The retardation value (Re5) measured at a wavelength of 550 nm
50) is in the range of 250 to 284 nm, and the retardation value (Re59) measured at a wavelength of 590 nm.
0) is in the range of 260-304 nm, and Re
The retardation plate according to (7), which satisfies the relationship of 590-Re550 ≧ 2 nm.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION [Retardation Plate] When a retardation plate is used as a λ / 4 plate, the retardation value (Re450) measured at a wavelength of 450 nm is 100 to 125 nm.
And the retardation value (Re590) measured at a wavelength of 590 nm is from 120 to 160 nm, and satisfies the relationship of Re590-Re450 ≧ 2 nm. More preferably, Re590-Re450 ≧ 5 nm, and most preferably, Re590-Re450 ≧ 10 nm. The retardation value (Re450) measured at a wavelength of 450 nm is 108 to 120 nm, the retardation value (Re550) measured at a wavelength of 550 nm is 125 to 142 nm, and the
Retardation value measured at 90 nm (Re590)
Is 130 to 152 nm, and Re590-
It is preferable to satisfy the relationship of Re550 ≧ 2 nm.
More preferably, Re590-Re550 ≧ 5 nm, and most preferably, Re590-Re550 ≧ 10 nm. Also, Re550−Re450 ≧ 10
nm is also preferable.

When a retardation plate is used as a λ / 2 plate, the retardation value (R
e450) is from 200 to 250 nm, and the wavelength 5
Retardation value measured at 90 nm (Re590)
Is 240 to 320 nm, and Re590-
The relationship of Re450 ≧ 2 nm is satisfied. Re590-R
e450 ≧ 4 nm, preferably Re590-
More preferably, Re450 ≧ 10 nm.
e590-Re450 ≧ 20 nm The retardation value (R
e450) is 216 to 240 nm and the wavelength is 550.
The retardation value (Re550) measured in nm is 2
50 to 284 nm, and the retardation value (Re590) measured at a wavelength of 590 nm is 260 to 304.
nm and Re590-Re550 ≧ 2 nm
Satisfy the relationship. It is preferable to satisfy the relationship of Re590-Re550 ≧ 4 nm, and Re590-Re55.
More preferably, 0 ≧ 10 nm, and Re590
Most preferably, -Re550 ≧ 20 nm. Further, it is also preferable that Re550−Re450 ≧ 20 nm. The retardation value (Re) is calculated according to the following equation. Retardation value (Re) = (nx−ny) × d where nx is the in-plane refractive index of the retardation plate in the slow axis direction (in-plane maximum refractive index); ny is the retardation The index of refraction in the direction perpendicular to the slow axis in the plane of the plate; and d is
This is the thickness (nm) of the phase difference plate.

Further, the retardation plate of the present invention preferably satisfies the following expression. 1 ≦ (nx−nz) / (nx−ny) ≦ 2, where nx is the in-plane refractive index in the plane of the retardation plate; ny is the in-plane retardation of the retardation plate Is the refractive index in the direction perpendicular to the axis; and nz is the refractive index in the thickness direction.

The thickness of one polymer film constituting the retardation plate is preferably 5 to 1000 μm, more preferably 10 to 500 μm,
More preferably, it is 40 to 200 μm.
Most preferably, the four plates have a thickness of 70 to 120 μm.

[Polymer] The polymer of the polymer film is preferably a cellulose ester, more preferably a lower fatty acid ester of cellulose. 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). Cellulose acetate is particularly preferred. Mixed fatty acid esters such as cellulose acetate propionate and cellulose acetate butyrate may be used. The average degree of acetylation (acetylation degree) of cellulose acetate is preferably from 45.0 to 62.5%, more preferably from 55.0 to 61.0%, and more preferably from 56.0 to 60.5%. % Is most preferred.

[Retardation raising agent] In order to adjust the retardation value at each wavelength, a retardation raising agent can be added to the polymer film.
The retardation increasing agent is preferably used in the range of 0.05 to 20 parts by mass, more preferably in the range of 0.1 to 10 parts by mass, and more preferably 0.2 to 10 parts by mass, based on 100 parts by mass of the polymer. It is more preferably used in the range of from 5 to 5 parts by mass, and most preferably used in the range of from 0.5 to 2 parts by mass. Two or more retardation increasing agents may be used in combination. The retardation increasing agent preferably has a maximum absorption in a wavelength region of 250 to 400 nm. It is preferable that the retardation increasing agent has substantially no absorption in the visible region.

As the retardation increasing agent, a compound having at least two aromatic rings is preferably used, and a compound having a molecular structure which does not hinder the conformation of the two aromatic rings is more preferable. . In the present specification, the “aromatic ring” includes an aromatic hetero ring in addition to an aromatic hydrocarbon ring. The aromatic hydrocarbon ring is particularly preferably a 6-membered ring (that is, a benzene ring). Aromatic heterocycles are generally unsaturated heterocycles. The aromatic hetero ring is preferably a 5-, 6-, or 7-membered ring, more preferably a 5- or 6-membered ring. Aromatic heterocycles generally have the most double bonds. As the hetero atom, a nitrogen atom, an oxygen atom and a sulfur atom are preferable, and a nitrogen atom is particularly preferable. Examples of the aromatic hetero ring include a furan ring, a thiophene ring, a pyrrole ring, an oxazole ring, an isoxazole ring, a thiazole ring, an isothiazole ring, an imidazole ring, a pyrazole ring, a furazane ring, a triazole ring, a pyran ring, and a pyridine ring. , Pyridazine ring, pyrimidine ring, pyrazine ring and 1,3,5-triazine ring. As the aromatic ring, a benzene ring, a furan ring, a thiophene ring, a pyrrole ring, an oxazole ring, a thiazole ring, an imidazole ring,
A triazole ring, a pyridine ring, a pyrimidine ring, a pyrazine ring and a 1,3,5-triazine ring are preferred.

The number of aromatic rings contained in the retardation increasing agent is preferably 2 to 20, and preferably 2 to 12
Is more preferably 2 to 8, more preferably 2 to 6, and particularly preferably at least one 1,3,5-triazine ring. The bonding relationship between two aromatic rings can be classified into (a) a case where a condensed ring is formed, (b) a case where they are directly connected by a single bond, and (c) a case where they are bonded via a linking group. , A spiro bond cannot be formed). The connection relationship may be any of (a) to (c).

Examples of the condensed ring of (a) (condensed ring of two or more aromatic rings) include an indene ring, a naphthalene ring, an azulene ring, a fluorene ring, a phenanthrene ring, an anthracene ring, an acenaphthylene ring, a biphenylene ring, Naphthacene ring, pyrene ring, indole ring, isoindole ring, benzofuran ring, benzothiophene ring, indolizine ring, benzoxazole ring, benzothiazole ring, benzimidazole ring, benzotriazole ring, purine ring, indazole ring, chromene ring, quinoline Ring, isoquinoline ring,
A quinolidine ring, a quinazoline ring, a cinnoline ring, a quinoxaline ring, a phthalazine ring, a pteridine ring, a carbazole ring, an acridine ring, a phenanthridine ring, a xanthene ring, a phenazine ring, a phenothiazine ring, a phenoxatiin ring, a phenoxazine ring and a thianthrene ring; included. Preferred are a naphthalene ring, an azulene ring, an indole ring, a benzoxazole ring, a benzothiazole ring, a benzimidazole ring, a benzotriazole ring and a quinoline ring. The single bond in (b) is preferably a bond between carbon atoms of two aromatic rings. Two aromatic rings may be linked by two or more single bonds to form an aliphatic ring or a non-aromatic heterocyclic ring between the two aromatic rings.

The connecting group (c) is also preferably bonded to carbon atoms of two aromatic rings. The linking group is an alkylene group, alkenylene group, alkynylene group, -CO-, -O
-, -NH-, -S- or a combination thereof is preferred. Examples of the linking group consisting of a combination are shown below. Note that the left and right relationships in the following examples of the linking group may be reversed. c1: -CO-O-c2: -CO-NH-c3: -alkylene-O-c4: -NH-CO-NH-c5: -NH-CO-O-c6: -O-CO-O-c7: -O-alkylene-O-c8: -CO-alkenylene-c9: -CO-alkenylene-NH-c10: -CO-alkenylene-O-c11: -alkylene-CO-O-alkylene-O-CO
-Alkylene-c12: -O-alkylene-CO-O-alkylene-O-
CO-alkylene-O-c13: -O-CO-alkylene-CO-O-c14: -NH-CO-alkenylene- c15: -O-CO-alkenylene-

The aromatic ring and the linking group may have a substituent. Examples of the substituent include a halogen atom (F, C
l, Br, I), hydroxyl, carboxyl, cyano, amino, nitro, sulfo, carbamoyl, sulfamoyl, ureido, alkyl, alkenyl, alkynyl, aliphatic acyl, aliphatic acyloxy, alkoxy, alkoxycarbonyl , Alkoxycarbonylamino group, alkylthio group, alkylsulfonyl group, aliphatic amide group, aliphatic sulfonamide group, aliphatic substituted amino group, aliphatic substituted carbamoyl group, aliphatic substituted sulfamoyl group, aliphatic substituted ureido group and non-aromatic Group heterocyclic groups.

The alkyl group preferably has 1 to 8 carbon atoms. A chain alkyl group is preferable to a cyclic alkyl group, and a linear alkyl group is particularly preferable.
The alkyl group may further have a substituent (eg, hydroxy, carboxy, alkoxy group, alkyl-substituted amino group). Examples of alkyl groups (including substituted alkyl groups) include methyl, ethyl, n-butyl, n-hexyl,
-Hydroxyethyl, 4-carboxybutyl, 2-methoxyethyl and 2-diethylaminoethyl. The alkenyl group preferably has 2 to 8 carbon atoms. A chain alkenyl group is preferable to a cyclic alkenyl group, and a linear alkenyl group is particularly preferable.
The alkenyl group may further have a substituent. Examples of the alkenyl group include vinyl, allyl and 1-hexenyl. The alkynyl group preferably has 2 to 8 carbon atoms. A chain alkynyl group is preferable to a cyclic alkynyl group, and a linear alkynyl group is particularly preferable. The alkynyl group may further have a substituent. Examples of the alkynyl group include ethynyl, 1-butynyl and 1-hexynyl.

The number of carbon atoms of the aliphatic acyl group is 1 to 1
It is preferably 0. Examples of the aliphatic acyl group include acetyl, propanoyl and butanoyl. The aliphatic acyloxy group preferably has 1 to 10 carbon atoms. Examples of the aliphatic acyloxy group include acetoxy. The alkoxy group preferably has 1 to 8 carbon atoms. The alkoxy group may further have a substituent (eg, an alkoxy group). Examples of alkoxy groups (including substituted alkoxy groups) include methoxy, ethoxy, butoxy and methoxyethoxy. The alkoxycarbonyl group preferably has 2 to 10 carbon atoms. Examples of the alkoxycarbonyl group include methoxycarbonyl and ethoxycarbonyl. The alkoxycarbonylamino group preferably has 2 to 10 carbon atoms. Examples of the alkoxycarbonylamino group include methoxycarbonylamino and ethoxycarbonylamino.

The number of carbon atoms of the alkylthio group is 1 to 1
It is preferably 2. Examples of the alkylthio group include methylthio, ethylthio and octylthio.
The alkylsulfonyl group preferably has 1 to 8 carbon atoms. Examples of the alkylsulfonyl group include methanesulfonyl and ethanesulfonyl. The aliphatic amide group preferably has 1 to 10 carbon atoms. Examples of the aliphatic amide group include acetamide. The aliphatic sulfonamide group preferably has 1 to 8 carbon atoms. Examples of the aliphatic sulfonamide group include methanesulfonamide, butanesulfonamide and n-octanesulfonamide. The aliphatic substituted amino group preferably has 1 to 10 carbon atoms. Examples of the aliphatic substituted amino group include dimethylamino, diethylamino and 2-carboxyethylamino. The aliphatic substituted carbamoyl group preferably has 2 to 10 carbon atoms. Examples of the aliphatic substituted carbamoyl group include methylcarbamoyl and diethylcarbamoyl. The aliphatic substituted sulfamoyl group preferably has 1 to 8 carbon atoms. Examples of the aliphatic substituted sulfamoyl group include methylsulfamoyl and diethylsulfamoyl. The aliphatic substituted ureido group preferably has 2 to 10 carbon atoms. Examples of the aliphatic substituted ureido group include methyl ureide. Examples of the non-aromatic heterocyclic group include piperidino and morpholino. The molecular weight of the retardation increasing agent is preferably from 300 to 800.
000-111914 and 2000-275434.

[Infrared Absorber] In order to adjust the retardation value at each wavelength, an infrared absorber can be added to the polymer film. The infrared absorber is preferably used in the range of 0.01 to 5 parts by mass, more preferably in the range of 0.02 to 2 parts by mass, and more preferably 0.05 to 5 parts by mass, based on 100 parts by mass of the polymer. It is more preferably used in the range of 1 part by mass, and most preferably used in the range of 0.1 to 0.5 part by mass.
Two or more infrared absorbers may be used in combination. The infrared absorber preferably has a maximum absorption in a wavelength range of 750 to 1100 nm, and more preferably has a maximum absorption in a wavelength range of 800 to 1000 nm. It is preferred that the infrared absorber has substantially no absorption in the visible region.

It is preferable to use an infrared absorbing dye or an infrared absorbing pigment as the infrared absorbing agent, and it is particularly preferable to use an infrared absorbing dye. The infrared absorbing dye includes an organic compound and an inorganic compound. It is preferable to use an infrared absorbing dye which is an organic compound. Organic infrared absorbing dyes include cyanine compounds, metal chelate compounds, aminium compounds, diimonium compounds, quinone compounds, squarylium compounds and methine compounds. For the infrared absorbing dye, coloring material, 61 [4] 2
15-226 (1988), and Chemical Industry, 43-5.
3 (1986, May).

When examining the types of dyes from the viewpoint of infrared absorption function or absorption spectrum, infrared absorption dyes developed in the technical field of silver halide photographic materials are excellent. Infrared absorbing dyes developed in the technical field of silver halide photographic light-sensitive materials include dihydroperimidine squarylium dyes (described in US Pat. No. 5,380,635 and Japanese Patent Application No. 8-189817) and cyanine dyes (JP-A No. No. 62-123454, No. 3-138640, No. 3
-21542, 3-226736, 5-31
Nos. 3305 and 6-43583, Japanese Patent Application No. 7-435.
269097 and EP 0430244), pyrylium dyes (JP-A-3-13864).
Nos. 0 and 3-21542) and diimmonium dyes (JP-A-3-138640 and JP-A-3-2115).
No. 42), pyrazolopyridone dyes (described in JP-A-2-282244), indoaniline dyes (described in JP-A-5-323500 and JP-A-5-323501), polymethine dyes (described in JP-A-3-26765). Nos. 4,190,343 and EP 37796.
No. 1), oxonol dyes (JP-A-3-93)
No. 46), anthraquinone dyes (Japanese Unexamined Patent Publication No.
13654), a naphthalocyanine dye (described in US Pat. No. 5,099,899) and a naphtholactam dye (described in European Patent 568,267).

[Production of polymer film] It is preferable to produce a polymer film by a solvent casting method. In the solvent casting method, a film is manufactured using a solution (dope) in which a polymer is dissolved in an organic solvent. The organic solvent is an ether having 3 to 12 carbon atoms,
It is preferable to include a solvent selected from ketones having 3 to 12 carbon atoms, esters having 3 to 12 carbon atoms, and halogenated hydrocarbons having 1 to 6 carbon atoms. Ethers, ketones and esters may have a cyclic structure. A compound having two or more functional groups of ether, ketone and ester (that is, -O-, -CO- and -COO-) can also be used as the organic solvent. The organic solvent may have another functional group such as an alcoholic hydroxyl group. In the case of an organic solvent having two or more types of functional groups, the number of carbon atoms may be within the specified range of the compound having any one of the functional groups.

Examples of the ethers having 3 to 12 carbon atoms include diisopropyl ether, dimethoxymethane, dimethoxyethane, 1,4-dioxane, 1,3-dioxolan, tetrahydrofuran, anisole and phenetole. Examples of the ketones having 3 to 12 carbon atoms include acetone, methyl ethyl ketone, diethyl ketone, diisobutyl ketone, cyclohexanone and methylcyclohexanone. Examples of the esters having 3 to 12 carbon atoms include ethyl formate, propyl formate, pentyl formate, methyl acetate, ethyl acetate and pentyl acetate. Examples of the organic solvent having two or more types of functional groups include
Includes 2-ethoxyethyl acetate, 2-methoxyethanol and 2-butoxyethanol. The number of carbon atoms of the halogenated hydrocarbon is preferably 1 or 2, and most preferably 1. The halogen of the halogenated hydrocarbon is preferably chlorine. The proportion of halogen atoms substituted by halogen atoms in halogenated hydrocarbons is preferably 25 to 75 mol%, and preferably 3 to 75 mol%.
The content is more preferably 0 to 70 mol%, still more preferably 35 to 65 mol%, and 40 to 60 mol%.
Most preferably, it is mol%. Methylene chloride is a typical halogenated hydrocarbon. Two or more organic solvents may be used as a mixture.

The polymer solution can be prepared by a general method. The general method means that the treatment is performed at a temperature of 0 ° C. or higher (normal temperature or high temperature). The solution can be prepared using a dope preparation method and apparatus in a usual solvent casting method. In the case of a general method, it is preferable to use a halogenated hydrocarbon (particularly, methylene chloride) as the organic solvent. The amount of the polymer is adjusted so that the obtained solution contains 10 to 40% by mass. More preferably, the amount of polymer is from 10 to 30% by weight. In the organic solvent (main solvent), any additives described below may be added.
The solution can be prepared by stirring the polymer and the organic solvent at room temperature (0 to 40 ° C.). The highly concentrated solution may be stirred under pressure and heating conditions. Specifically, the polymer and the organic solvent are placed in a pressurized container and hermetically sealed, and the mixture is stirred while being heated under pressure to a temperature not lower than the boiling point of the solvent at normal temperature and in a range where the solvent does not boil. The heating temperature is usually 40 ° C. or higher, preferably 60 to 2
It is 00 ° C, more preferably 80 to 110 ° C.

The components may be roughly mixed in advance and then placed in a container. Moreover, you may put in a container sequentially. The container must be configured to be able to stir. The container can be pressurized by injecting an inert gas such as nitrogen gas. Further, an increase in the vapor pressure of the solvent due to heating may be used.
Alternatively, each component may be added under pressure after the container is sealed. When heating, it is preferable to heat from outside the container. For example, a jacket-type heating device can be used. Alternatively, a plate heater may be provided outside the container, and the entire container may be heated by circulating the liquid through piping. It is preferable to provide a stirring blade inside the container and stir using the stirring blade. The stirring blade preferably has a length reaching the vicinity of the container wall. At the end of the stirring blade, a scraping blade is preferably provided to renew the liquid film on the container wall. Instruments such as a pressure gauge and a thermometer may be installed in the container. Dissolve each component in the solvent in the container.
The prepared dope is taken out of the vessel after cooling, or is taken out and then cooled using a heat exchanger or the like.

The solution can be prepared by a cooling dissolution method. In the cooling dissolution method, the polymer can be dissolved even in an organic solvent that is difficult to dissolve by a normal dissolution method. In addition, even if it is a solvent which can dissolve a polymer by a usual dissolution method, the cooling dissolution method has an effect that a uniform solution can be obtained quickly. In the cooling dissolution method, first, a polymer is gradually added to an organic solvent with stirring at room temperature. The amount of polymer is between 10 and 4 in this mixture.
It is preferable to adjust so as to contain 0% by mass. More preferably, the amount of polymer is from 10 to 30% by weight. Further, an optional additive described below may be added to the mixture.

Next, the mixture is heated to -100 to -10 ° C (preferably -80 to -10 ° C, more preferably -50 to -10 ° C).
To -20 ° C, most preferably -50 to -30 ° C). The cooling can be performed, for example, in a dry ice / methanol bath (−75 ° C.) or a cooled diethylene glycol solution (−30 to −20 ° C.). Upon such cooling, the mixture of polymer and organic solvent solidifies. The cooling rate is preferably 4 ° C./min or more, and 8 ° C./min.
Minutes or more, and most preferably 12 ° C./minute or more. The higher the cooling rate, the better, but the theoretical upper limit is 10,000 ° C./sec.
0 ° C./sec is a technical upper limit, and 100 ° C./sec is a practical upper limit. The cooling rate is a value obtained by dividing the difference between the temperature at which the cooling is started and the final cooling temperature by the time from when the cooling is started to when the temperature reaches the final cooling temperature.

Further, the temperature is raised to 0 to 200 ° C (preferably 0 to 150 ° C, more preferably 0 to 120 ° C,
Upon heating to (most preferably 0 to 50 ° C.), the polymer dissolves in the organic solvent. The temperature may be raised only at room temperature or may be heated in a warm bath. Heating rate is 4
C./min or more, more preferably 8 ° C./min or more, and most preferably 12 ° C./min or more. The heating rate is preferably as fast as possible.
00 ° C / sec is the theoretical upper limit, 1000 ° C / sec is the technical upper limit, and 100 ° C / sec is the practical upper limit. Note that the heating rate is a value obtained by dividing the difference between the temperature at which heating is started and the final heating temperature by the time from when the heating is started until the final heating temperature is reached. . As described above, a uniform solution is obtained. If the dissolution is insufficient, the operation of cooling and heating may be repeated.
Whether or not the dissolution is sufficient can be determined only by visually observing the appearance of the solution.

In the cooling dissolution method, it is preferable to use a closed container in order to avoid water contamination due to condensation during cooling. Also, in the cooling and heating operation, pressurization during cooling,
By reducing the pressure during the heating, the dissolution time can be shortened. In order to perform pressurization and decompression, it is desirable to use a pressure-resistant container. According to differential scanning calorimetry (DSC), a 20% by mass solution of cellulose acetate (degree of acetylation: 60.9%, viscosity average polymerization degree: 299) dissolved in methyl acetate by a cooling dissolution method was 3%.
A pseudo phase transition point between the sol state and the gel state exists near 3 ° C., and below this temperature, the gel state becomes uniform. Therefore,
This solution must be stored at a temperature equal to or higher than the quasi phase transition temperature, preferably at a temperature of about 10 ° C. plus the gel phase transition temperature. However, the pseudo phase transition temperature varies depending on the average acetylation degree of cellulose acetate, the average degree of viscosity polymerization, the solution concentration, and the organic solvent used.

From the prepared polymer solution (dope), a polymer film is produced by a solvent casting method. The dope is cast on a drum or band and the solvent is evaporated to form a film. The concentration of the dope before casting is preferably adjusted so that the solid content is 18 to 35%. It is preferable that the surface of the drum or the band is finished in a mirror state. The casting and drying methods in the solvent casting method are described in US Pat.
No. 36310, No. 2367603, No. 2492078
Nos. 2492977, 2492978, 26
No. 07704, No. 2739069, No. 2739070
Nos., British Patent Nos. 640731 and 736892, Japanese Patent Publication Nos. 45-4554 and 49-5614,
JP-A-60-176834 and JP-A-60-203430
And JP-A-62-115035. The dope is preferably cast on a drum or band having a surface temperature of 10 ° C. or less. It is preferable to dry the film by blowing it for 2 seconds or more. The obtained film is peeled off from the drum or band, and further heated at 100 to 160 ° C.
It is also possible to evaporate the residual solvent by drying with a high-temperature air whose temperature is changed successively. The above method is described in Tokuhei 5-178.
No. 44 discloses this. According to this method, the time from casting to stripping can be reduced. In order to carry out this method, it is necessary that the dope gels at the surface temperature of the drum or band during casting. The solution (dope) prepared according to the present invention satisfies this condition. The thickness of the film to be manufactured is 40 to 12
It is preferably 0 μm, more preferably 70 to 100 μm.

[Plasticizer] A plasticizer can be added to the polymer film in order to improve mechanical properties or to increase the drying speed. As a plasticizer,
Phosphate or carboxylate esters are used. Examples of phosphate esters include triphenyl phosphate (TPP) and tricresyl phosphate (TCC).
P) is included. Representative carboxylic esters include phthalic esters and citric esters. Examples of phthalate esters include dimethyl phthalate (DM
P), diethyl phthalate (DEP), dibutyl phthalate (DBP), dioctyl phthalate (DOP), diphenyl phthalate (DPP) and diethylhexyl phthalate (DEHP). Examples of citrate esters include O-acetyl triethyl citrate (OACT
E) and tributyl O-acetylcitrate (OACT
B) is included. Examples of other carboxylic esters include butyl oleate, methylacetyl ricinoleate,
It includes dibutyl sebacate and various trimellitate esters. Phthalate ester plasticizers (DMP, DE
P, DBP, DOP, DPP, DEHP) are preferably used. DEP and DPP are particularly preferred. The amount of the plasticizer added is preferably 0.1 to 25% by mass of the amount of the polymer, more preferably 1 to 20% by mass, and most preferably 3 to 15% by mass.

[Deterioration inhibitor] The polymer film may be added with a degradation inhibitor (eg, antioxidant, peroxide decomposer, radical inhibitor, metal deactivator, acid scavenger, amine). Good. Regarding the deterioration inhibitor, see JP-A-3-1992
No. 01, 5-1907073, 5-194789
And JP-A-5-271471 and JP-A-6-107854. The amount of the deterioration inhibitor added is preferably 0.01 to 1% by mass, more preferably 0.01 to 0.2% by mass of the solution (dope) to be prepared. When the amount is less than 0.01% by mass, the effect of the deterioration inhibitor is hardly recognized. 1% by mass
Exceeding the limit may cause bleed-out (bleeding-out) of the deterioration inhibitor to the film surface. Particularly preferred examples of the deterioration inhibitor include butylated hydroxytoluene (BHT) and tribenzylamine (TBA).

[Stretching Treatment] The polymer film is further subjected to a stretching treatment to obtain a refractive index (refractive index n in the in-plane slow axis direction).
It is preferable to adjust x, the refractive index ny in the direction perpendicular to the in-plane slow axis, and the refractive index nz in the thickness direction. When the intrinsic birefringence is positive, the refractive index increases in the direction in which the polymer chains are oriented. When such a polymer having a positive intrinsic birefringence is stretched, the refractive index usually becomes nx> ny ≧ nz. This is because the x-component of the polymer chain oriented in the in-plane direction is increased by stretching, and the z-component is minimized. Thus, 1 ≦ (nx−nz) / (nx−
ny) can be satisfied. Further, (nx
In order to satisfy the relationship of −nz) / (nx−ny) ≦ 2, the refractive index may be adjusted by controlling the stretching ratio of uniaxial stretching or by performing unbalanced biaxial stretching.
Specifically, uniaxial stretching or unbalanced biaxial stretching is performed so that the maximum stretching ratio SA and the stretching ratio SB in the direction perpendicular to the stretching direction satisfy the relationship of 1 <SA / SB ≦ 3. What is necessary is just to implement. The stretching ratio is a relative value when the length before stretching is set to 1. SB may be a value less than 1 (in other words, contract). If the relationship of the above expression is satisfied, SB may be a value less than 1. Further, the stretching ratio is such that the front retardation is λ /
4 or λ / 2. The stretching process may be a simultaneous process or a sequential process.

[Surface Treatment] In the present invention, the adhesiveness to a polarizing film, a transparent protective film (used for a polarizing plate), a glass substrate, a plastic substrate, etc. is improved by treating one or both surfaces of the polymer film. As the surface treatment, a corona discharge treatment, a glow discharge treatment, a flame treatment, an acid treatment, an alkali treatment, or an ultraviolet irradiation treatment is preferably performed. As the surface treatment of the polymer film, a silane coupling agent treatment may be performed, or an undercoat layer such as an acrylate (including an epoxy acrylate, a urethane acrylate, and a silicone acrylate) may be provided.

The corona discharge treatment and the glow discharge treatment can be performed using a commercially available discharge treatment machine. The discharge treatment is preferably performed in the presence of water vapor. The partial pressure of water vapor is 1
0 to 100%, preferably 40 to 90%
Is more preferable. It is preferable to perform a discharge treatment after preheating the polymer film. The preheating temperature is preferably 50 ° C. or higher, more preferably 70 ° C. or higher, and most preferably 80 ° C. or higher. The upper limit of the preheating temperature is the glass transition temperature of the polymer film. In the corona discharge treatment, a high voltage is applied between an electrode connected to a high voltage generator and a dielectric roll, and a polymer film (particularly preferably a cellulose acetate film) is generated during the corona discharge generated between the electrode and the dielectric roll. ) Is placed or moved. In this specification, the frequency of a high voltage applied between an electrode and a dielectric roll is referred to as a discharge frequency. It is convenient to perform corona discharge treatment in the atmosphere.However, if necessary, seal the treatment equipment in a sealed or semi-sealed state, and treat it in a state filled with other gas or a mixture of other gas and atmosphere. You can also. Examples of the gas include a nitrogen gas, an argon gas, and an oxygen gas. In the corona discharge treatment, the discharge frequency is generally 50 Hz to 5000.
kHz, and more preferably 5 kHz to several 100 kHz. In the corona treatment, if the discharge frequency is too low, the discharge becomes unstable and pinholes are formed in the polymer film (cellulose acetate film), which is not preferable. On the other hand, if the discharge frequency is too high, an additional device for impedance matching is required, which is not preferable because the price of the device increases. In order to improve the adhesiveness of the polymer film of the present invention, the corona discharge treatment of the polymer film (particularly preferably cellulose acetate film) is carried out at 0.001 kV · A · min / m ² -5
kV · A · min / m ² , preferably 0.01 k
It is more preferable to set VA · min / m ^{2 to 1} kV · A · min / m ² . The distance between the electrode and the dielectric roll is 0.5
To 2.5 mm, preferably 1.0 to 2.
More preferably, it is 0 mm. The degree of vacuum in the glow discharge treatment is preferably 0.005 to 20 Torr, and more preferably 0.02 to 2 Torr. The voltage of the glow discharge treatment is 500 to 5
000V, preferably 500-3000V
Is more preferable. The glow discharge frequency is 5
0 Hz to 20 MHz, preferably 1 KHz
The frequency is more preferably from 1 MHz to 1 MHz. The glow discharge intensity is preferably 0.01 to 5 KV · A · min / m ² , and more preferably 0.15 to 1 KV · A · min / m ² . It is preferable that the polymer film after the discharge treatment is immediately cooled.

In the flame treatment, the mixing ratio of gas (natural gas, propane gas) and air is important. The volume ratio of gas / air is preferably 1/13 to 1/21,
More preferably, it is 1/14 to 1/20. The calorific value of the flame treatment per area of the polymer film is preferably 1 to 50 kcal / m ² . The distance between the tip of the inner flame of the flame and the polymer film is preferably 4 cm or less. The acid used for the acid treatment is preferably an inorganic acid such as hydrochloric acid, sulfuric acid or nitric acid. The alkali used for the alkali treatment is preferably an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide. The acid treatment or the alkali treatment is carried out by immersing the surface of the polymer film on the polarizing film side in an acid or alkali aqueous solution, or by spraying an acid or alkali aqueous solution. The specified concentration of hydroxide ions in the aqueous acid solution or the aqueous alkali solution is preferably from 0.1 N to 3.0 N, more preferably from 0.5 to 2.0 N. The immersion time is preferably 30 seconds to 10 minutes. The temperature of the acid or alkali aqueous solution is 0
It is preferably in the range of -90 ° C, more preferably in the range of 40-70 ° C. After immersion or spraying, the polymer film is preferably washed with water and dried. The ultraviolet wavelength of the ultraviolet irradiation treatment is preferably from 220 to 380 nm. The irradiation light amount is 20
And preferably 10000 mJ / cm ² to 5 mJ / cm ^2.
More preferably from 0 to 2000 mJ / cm ^2, and most preferably 100 to 1500 mJ / cm ^2. The treatment temperature is preferably in the range of 10 ° C. to Tg (glass transition temperature of the polymer). It is particularly preferable to carry out an acid treatment or an alkali treatment. When a cellulose ester film is used as the polymer film used in the present invention, the acid treatment or the alkali treatment functions as a saponification treatment.

[Circularly Polarizing Plate] The λ / 4 plate and the polarizing film are
A circularly polarizing plate is obtained by laminating such that the angle between the in-plane slow axis of the four plates and the polarizing axis of the linear polarizing film is substantially 45 °. Substantially 45 ° means 40 to 50 °. The angle between the slow axis in the plane of the λ / 4 plate and the polarization axis of the polarizing film is preferably 41 to 49 °, and 42 °.
The angle is more preferably from 48 to 48 °, further preferably from 43 to 47 °, and most preferably from 44 to 46 °. The linear polarizing film includes an iodine-based polarizing film,
There are a dye-based polarizing film using a dichroic dye and a polyene-based polarizing film. The iodine-based polarizing film and the dye-based polarizing film are generally manufactured using a polyvinyl alcohol-based film. The polarization axis of the polarizing film corresponds to a direction perpendicular to the stretching direction of the film. It is preferable to provide a transparent protective film on the surface of the polarizing film opposite to the λ / 4 plate. It is preferable to provide an anti-reflection layer as the outermost layer.

[Reflection type liquid crystal display device] The retardation plate and the circularly polarizing plate of the present invention can be used in combination with various display devices. For example, a cathode ray tube (CR
T), plasma display (PDP), field
Examples include an emission display (FED), an inorganic EL device, an organic EL device, and a liquid crystal display device. By using the retardation plate and the circularly polarizing plate of the invention, reflection of external light from these display devices can be reduced. Among these display devices, it is preferable to use them in combination with a liquid crystal display device, and it is particularly preferable to use them in a reflection type liquid crystal display device.
FIG. 1 is a schematic diagram showing a basic configuration of a reflection type liquid crystal display device. The reflective liquid crystal display device shown in FIG. 1 includes, in order from the bottom, a lower substrate (1), a reflective electrode (2), a lower alignment film (3),
It comprises a liquid crystal layer (4), an upper alignment film (5), a transparent electrode (6), an upper substrate (7), a λ / 4 plate (8), and a polarizing film (9). The lower substrate (1) and the reflection electrode (2) constitute a reflection plate. The lower alignment film (3) to the upper alignment film (5) constitute a liquid crystal cell. The λ / 4 plate (8) can be arranged at an arbitrary position between the reflection plate and the polarizing film (9). In the case of color display, a color filter layer is further provided. The color filter layer is preferably provided between the reflective electrode (2) and the lower alignment film (3) or between the upper alignment film (5) and the transparent electrode (6). A reflective plate may be separately attached using a transparent electrode instead of the reflective electrode (2) shown in FIG. A metal plate is preferable as the reflector used in combination with the transparent electrode. 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 Japanese Patent No. 275620) on the surface of the reflector. 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.

The liquid crystal mode to be used is not particularly limited, but is a TN (twisted nematic) type, STN (Supper Twisted).
sted Nematic) type or HAN (Hybrid Aligned Nemat)
ic) type. The twist angle of the TN type liquid crystal cell is preferably 40 to 100 °, and
To 90 °, more preferably 60 to 80 °.
Most preferably, ゜. The value of the product (Δnd) of the refractive index anisotropy (Δn) of the liquid crystal layer and the thickness (d) of the liquid crystal layer is preferably 0.1 to 0.5 μm.
More preferably, it is 2 to 0.4 μm. STN
The twist angle of the liquid crystal cell is preferably 180 to 360 °, more preferably 220 to 270 °. The value of the product (Δnd) of the refractive index anisotropy (Δn) of the liquid crystal layer and the thickness (d) of the liquid crystal layer is 0.3 to 1.2.
μm, more preferably 0.5 to 1.0 μm. In the HAN type liquid crystal cell, it is preferable that the liquid crystal is substantially vertically aligned on one substrate and the pretilt angle on the other substrate is 0 to 45 °. The value of the product (Δnd) of the refractive index anisotropy (Δn) of the liquid crystal layer and the thickness (d) of the liquid crystal layer is 0.1 to 1.0 μm
And more preferably 0.3 to 0.8 μm. The substrate on which the liquid crystal is vertically aligned may be a substrate on the reflection plate side or a substrate on the transparent electrode side.

The reflection type liquid crystal display device can be used in a normally white mode in which the display is bright when the applied voltage is low and a dark display when the applied voltage is high, or in a normally black mode in which the display is dark when the applied voltage is low and bright when the applied voltage is high. be able to. Normally white mode is preferred.

[0046]

EXAMPLES Example 1 Preparation of Cellulose Acetate Film Cellulose acetate 12 having an average acetylation degree of 59.7% at room temperature.
0 parts by mass, 1.2 parts by mass of the following retardation raising agent,
A solution (dope) was prepared by mixing 9.36 parts by mass of triphenylene phosphate, 4.68 parts by mass of biphenyldiphenyl phosphate, 2.0 parts by mass of tribenzylamine, 538.2 parts by mass of methylene chloride, and 46.8 parts by mass of methanol. did.

[0047]

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The obtained dope was cast on a stainless steel band, the film was dried until it had self-supporting properties, and then the film was peeled off from the band. At that time, the residual solvent amount was 30% by mass. Thereafter, the film was dried at 120 ° C. for 15 minutes to reduce the residual solvent amount to 2% by mass or less, and then stretched at 130 ° C. in a direction parallel to the casting direction. The direction perpendicular to the stretching direction was allowed to shrink freely. After stretching, the film was dried at 120 ° C. for 30 minutes as it was, and then the stretched film was taken out. The residual solvent amount after stretching was 0.1% by mass. The thickness of the obtained film was 100 μm. About the obtained cellulose acetate film (X-1), an ellipsometer (M-150, JASCO Corporation)
Wavelengths of 450 nm, 550 nm, and 5 nm.
When the retardation values (Re) at 90 nm were measured, they were 120.5 nm and 137.5 n, respectively.
m, 143.4 nm. Therefore, this cellulose acetate film achieved λ / 4 in a wide wavelength range. Further, from the measurement of the refractive index by the Abbe refractometer and the measurement of the angle dependence of the retardation,
The refractive index nx in the in-plane slow axis direction, the refractive index ny in the direction perpendicular to the slow axis in the plane, and the refractive index nz in the thickness direction at 50 nm are determined, and (nx-nz) / (nx-ny) is obtained. The calculated value was 1.50.

(Surface Treatment of Cellulose Acetate Film) The obtained retardation plate was immersed in a 1.5 N aqueous solution of sodium hydroxide (50 ° C.) for 3 minutes, and then washed in a water washing bath at room temperature. Neutralized with 5N sulfuric acid and washed again in a water washing bath at room temperature. The laminate was dried with hot air at 100 ° C. Thus, a retardation plate of the present invention was produced.

(Preparation of Transparent Protective Film) A 100 μm-thick triacetylcellulose film whose surface has been subjected to an antireflection treatment (hereinafter abbreviated as AR treatment) and a 100 μm-thick triacetylcellulose film not subjected to the AR treatment are used. They were prepared and subjected to a surface treatment (saponification treatment) in the same manner as in the case of the retardation plate to produce a transparent protective film.

(Preparation of Circular Polarizing Plate) Iodine was adsorbed on a stretched polyvinyl alcohol film to prepare a polarizing film. A transparent protective film whose surface was subjected to AR treatment was attached to one side of the polarizing film using a polyvinyl alcohol-based adhesive. On the other side, a transparent protective film whose surface was not subjected to AR treatment was attached using a polyvinyl alcohol-based adhesive. A retardation plate was attached to the side of the thus-prepared polarizing plate on the side of the transparent protective film not subjected to the AR treatment, using an acrylic adhesive. The polarization axis of the polarizing film and the slow axis direction of the phase difference plate were arranged at 45 °. Thus, a circularly polarizing plate was produced. A circularly polarizing plate is attached to a glass plate using an acrylic adhesive, aged under high temperature and pressure, and then placed in a thermostat at 90 ° C.
Left for hours. Examination of the circularly polarizing plate revealed no problems such as peeling, generation of bubbles, and generation of wrinkles. Further examination after 500 hours (total 1000 hours) in a thermostat at 90 ° C. revealed no problems such as peeling, foaming or wrinkling.

(Preparation of Reflective Liquid Crystal Display Device) A glass substrate provided with an ITO transparent electrode and a glass substrate provided with an aluminum reflective electrode having fine irregularities were prepared.
A polyimide alignment film (SE-7992, manufactured by Nissan Chemical Industries, Ltd.) was formed on each of the two glass substrates on the electrode side, and rubbing treatment was performed. Two substrates were stacked via a 3.4 μm spacer so that the alignment films faced each other. The directions of the substrates were adjusted so that the rubbing directions of the two alignment films intersect at an angle of 110 °. Liquid crystal (MLC-6252, manufactured by Merck) was injected into the gap between the substrates to form a liquid crystal layer. Thus, the twist angle is 70 °, Δn
A TN liquid crystal cell having a value of d of 269 nm was produced. IT
A circularly polarizing plate was attached to the side of the glass substrate provided with the O transparent electrode via an adhesive. A 1 kHz rectangular wave voltage was applied to the manufactured reflective liquid crystal display device. White display 1.5
V, the black display was 4.5 V, and the visual evaluation was performed.
In both white display and black display, it was confirmed that there was no color and neutral gray was displayed.
Next, when the contrast ratio of the reflection luminance was measured using a measuring instrument (EZcontrast160D, manufactured by Eldim), the contrast ratio from the front was 20, and the viewing angle at which the contrast ratio was 3 was 120 ° or more in the vertical direction and the horizontal direction. It was 120 ° or more.

Example 2 (Surface Treatment of Cellulose Acetate Film) Example 1
On one side of the cellulose acetate film produced in
A 1.5N aqueous solution of sodium hydroxide (60 ° C.) was sprayed. Excess sodium hydroxide aqueous solution was scraped off with a bar coater. After 3 minutes, wash in a water bath at room temperature,
Neutralized with 1.5N sulfuric acid and washed again in a water washing bath at room temperature. Further, the film was dried with hot air at 100 ° C.
In this way, one side of the cellulose acetate film was saponified. Thus, a retardation plate of the present invention was produced. (Preparation of transparent protective film) AR-treated surface with a thickness of 100
A μm triacetyl cellulose film was subjected to a saponification treatment in the same manner as in the case of the retardation plate to produce a transparent protective film.

(Preparation of Circular Polarizing Plate) Iodine was adsorbed on a stretched polyvinyl alcohol film to prepare a polarizing film. A retardation plate was attached to one side of the polarizing film using a polyvinyl alcohol-based adhesive. On the opposite side, a transparent protective film was attached using a polyvinyl alcohol-based adhesive. The polarization axis of the polarizing film and the slow axis direction of the retardation plate are 4
It was arranged to be 5 mm. The saponified surface is on the polarizing film side. Thus, a circularly polarizing plate was produced. The circularly polarizing plate was attached to a glass plate using an acrylic adhesive, aged under high temperature and pressure, and then placed in a thermostat at 90 ° C. and left for 500 hours. Examination of the circularly polarizing plate revealed no problems such as peeling, generation of bubbles, and generation of wrinkles. 500 hours (total 1000 hours)
Time) Even after examination in a thermostat at 90 ° C., no problems such as peeling, generation of bubbles, and generation of wrinkles were found.

(Production of Liquid Crystal Display) A liquid crystal display was produced in the same manner as in Example 1 except that the above-mentioned circularly polarizing plate was used. A 1 kHz rectangular wave voltage was applied to the reflection type liquid crystal display device. Visual evaluation was performed with a white display of 1.5 V and a black display of 4.5 V. As a result, it was confirmed that neither white display nor black display had a hue and neutral gray was displayed. Next, a measuring machine (EZcontra
The contrast ratio of the reflected luminance was measured using a st160D (manufactured by Eldim Co.), and the contrast ratio from the front was 20.
It was 20 ° or more, and left and right 120 ° or more.

Example 3 (Surface Treatment of Cellulose Acetate Film) Example 1
A solid state corona treatment machine (6KVA model, Pillar
(Corona discharge treatment). The processing speed is 20 m / min, and the processing amount is 0.375 KV · A · min /
m ² , the discharge frequency was 9.6 KHz, and the gap clearance between the electrode and the dielectric roll was 1.6 mm. Thus, one surface of the cellulose acetate film was surface-treated. Thus, a retardation plate of the present invention was produced.

(Preparation of Circularly Polarizing Plate) A circularly polarizing plate was prepared in the same manner as in Example 1 except that the retardation plate surface-treated as described above was used. The circularly polarizing plate was attached to a glass plate using an acrylic adhesive, aged under high temperature and pressure, and then placed in a thermostat at 90 ° C. and left for 500 hours. Examination of the circularly polarizing plate revealed no problems such as peeling, generation of bubbles, and generation of wrinkles. Further examination after 500 hours (total 1000 hours) in a thermostat at 90 ° C. revealed no problems such as peeling, foaming or wrinkling.

(Preparation of Liquid Crystal Display) A liquid crystal display was prepared in the same manner as in Example 1 except that the above-mentioned circularly polarizing plate was used. A 1 kHz rectangular wave voltage was applied to the reflection type liquid crystal display device. Visual evaluation was performed with a white display of 1.5 V and a black display of 4.5 V. As a result, it was confirmed that neither white display nor black display had a hue and neutral gray was displayed. Next, a measuring machine (EZcontra
The contrast ratio of the reflected luminance was measured using a st160D (manufactured by Eldim Co.), and the contrast ratio from the front was 20.
It was 20 ° or more, and left and right 120 ° or more.

Example 4 (Surface Treatment of Cellulose Acetate Film) Example 1
Using a cylindrical 1KW quartz high-pressure mercury lamp on one side of the cellulose acetate film prepared in
UV irradiation treatment was performed for minutes. The distance between the cellulose acetate film and the lamp was 10 cm, the lamp width was 50 cm, the arc length of the lamp was 30 cm, the main wavelength of the ultraviolet light was 365 nm, and the irradiation light amount was 500 mJ / cm ² . Thus, one surface of the cellulose acetate film was surface-treated. Thus, a retardation plate of the present invention was produced.

(Preparation of Elliptically Polarizing Plate) A circularly polarizing plate was prepared in the same manner as in Example 1 except that the retardation plate surface-treated as described above was used. The circularly polarizing plate was attached to a glass plate using an acrylic adhesive, aged under high temperature and pressure, and then placed in a thermostat at 90 ° C. and left for 500 hours. Examination of the circularly polarizing plate revealed no problems such as peeling, generation of bubbles, and generation of wrinkles. Further examination after 500 hours (total 1000 hours) in a thermostat at 90 ° C. revealed no problems such as peeling, foaming or wrinkling.

(Preparation of Liquid Crystal Display) A liquid crystal display was prepared in the same manner as in Example 1 except that the above-mentioned circularly polarizing plate was used. A 1 kHz rectangular wave voltage was applied to the reflection type liquid crystal display device. Visual evaluation was performed with a white display of 1.5 V and a black display of 4.5 V. As a result, it was confirmed that neither white display nor black display had a hue and neutral gray was displayed. Next, a measuring machine (EZcontra
The contrast ratio of the reflected luminance was measured using a st160D (manufactured by Eldim Co.), and the contrast ratio from the front was 20.
It was 20 ° or more, and left and right 120 ° or more.

Example 5 (Preparation of Retardation Plate) The dry film thickness of the entire film was 200 μm.
m, a cellulose acetate film was produced in the same manner as in Example 1, except that the amount of the dope applied was changed. In addition, the produced cellulose acetate film (X-2) was subjected to the same surface treatment as in Example 1 to produce a retardation film of the present invention. About the produced cellulose acetate film (X-2), an ellipsometer (M-
150, manufactured by JASCO Corporation) at a wavelength of 450 n.
m, 550 nm and 590 nm, the retardation values (Re) were measured.
6 nm, 275.1 nm and 290.2 nm. Therefore, this cellulose acetate film achieved λ / 2 in a wide wavelength range. Further, from the measurement of the refractive index by the Abbe refractometer and the measurement of the angle dependence of the retardation, the refractive index nx in the in-plane slow axis direction and the refractive index in the direction perpendicular to the in-plane slow axis at a wavelength of 550 nm are obtained. ny and the refractive index nz in the thickness direction are obtained, and (nx−n
z) / (nx-ny) was calculated to be 1.54
Met.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a basic configuration of a reflective liquid crystal display device.

[Explanation of symbols]

 Reference Signs List 1 lower substrate 2 reflective electrode 3 lower alignment film 4 liquid crystal layer 5 upper alignment film 6 transparent electrode 7 upper substrate 8 λ / 4 plate 9 polarizing film

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G02F 1/13363 G02F 1/13363 F-term (Reference) 2H049 BA02 BA03 BA06 BA07 BA27 BB43 BB49 BB52 BB61 BC03 BC09 BC10 BC22 2H091 FA08X FA08Z FA11X FA11Z FA14Z GA16 HA07 HA08 HA10 KA02 LA30 4F071 AA09 AC12 AF35Y AH16 BA02 BB02 BB07 BC01 4F073 AA01 BA03 BA42 BA52 BB01 CA21 CA45 EA32 EA33 EA34 EA42 GA03 4J002 AB02 EU031

Claims (8)

[Claims] 1. A retardation value (Re450) measured at a wavelength of 450 nm is in the range of 100 to 125 nm, a retardation value (Re590) measured at a wavelength of 590 nm is in a range of 120 to 160 nm, and Re590-Re450. A retardation plate comprising a single polymer film satisfying a relationship of ≧ 2 nm, wherein one or both surfaces of the polymer film are subjected to a surface treatment. 2. A retardation value (Re450) measured at a wavelength of 450 nm is in the range of 108 to 120 nm, a retardation value (Re550) measured at a wavelength of 550 nm is in a range of 125 to 142 nm,
The retardation value (Re5) measured at a wavelength of 590 nm
90) is in the range of 130 to 152 nm and R
The retardation plate according to claim 1, wherein a relationship of e590-Re550 ≧ 2 nm is satisfied. 3. The retardation plate according to claim 1, wherein the polymer film is made of a cellulose ester film, and the cellulose ester film contains a compound having at least two aromatic rings. 4. The polymer film has a refractive index nx in the in-plane slow axis direction, a refractive index ny in a direction perpendicular to the slow axis in the plane, and a refractive index nz in the thickness direction of 1 ≦ (nx -N
The retardation plate according to claim 1, comprising a cellulose ester film satisfying a relationship of z) / (nx-ny) ≤2. 5. A circle in which a retardation plate and a linear polarizing film are laminated such that the angle between the in-plane slow axis of the retardation plate and the polarization axis of the linear polarizing film is substantially 45 °. A polarizing plate,
The retardation plate has a retardation value (Re450) measured at a wavelength of 450 nm in the range of 100 to 125 nm, and a retardation value (R450) measured at a wavelength of 590 nm.
e590) is in the range of 120 to 160 nm, and Re
590-Re450. A circularly polarizing plate comprising a single polymer film satisfying a relationship of 2 nm and having one or both surfaces of the polymer film subjected to a surface treatment. 6. A reflection type liquid crystal display device using the phase difference plate according to claim 1. 7. A retardation value (Re450) measured at a wavelength of 450 nm is in the range of 200 to 250 nm, a retardation value (Re590) measured at a wavelength of 590 nm is in a range of 240 to 320 nm, and Re590- A retardation plate comprising a single polymer film satisfying a relationship of Re450 ≧ 2 nm, wherein one or both surfaces of the polymer film are subjected to a surface treatment. 8. A retardation value (Re450) measured at a wavelength of 450 nm is in a range of 216 to 240 nm, a retardation value (Re550) measured at a wavelength of 550 nm is in a range of 250 to 284 nm,
And a retardation value (R
e590) is in the range of 260 to 304 nm, and satisfies the relationship of Re590-Re550 ≧ 2 nm.