JP2002099388A - Touch panel, reflection type liquid crystal display device and guest host type liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To apply one polymer film realizing λ/4 over the entire visible light area to a touch panel and to obtain a reflection type liquid crystal display device with the touch panel, whose display quality such as contrast and tints are improved. SOLUTION: In this touch panel in which two transparent conductive substrates where at least one side is provided with a transparent conducting layer are arranged with their transparent conducting layers facing each other, and at least one transparent conductive substrate is a λ/4 plate or a λ/4 plate is layered on the surface of at least one transparent conductive substrate, one cellulose ester film is used as the λ/4 plate, in which a retardation value (Re 450) measured with 450 nm wavelength ranges between 100 and 125 nm, and a retardation value (Re 590) measured with 590 nm wavelength ranges also between 120 to 160 nm, and which satisfies the relation of Re 590-Re 450>=2 nm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a touch panel using a λ / 4 plate. Further, the present invention also relates to a reflection type liquid crystal display device or a guest-host type liquid crystal display device using a touch panel.

[0002]

2. Description of the Related Art There are various types of touch panels, such as a resistive type, an optical type, a capacitive type, an ultrasonic type and an electromagnetic induction type. The resistive film method is characterized in that it is relatively inexpensive, and it is easy to reduce the thickness and weight. Since the resistive film method allows external input simply by being mounted on the surface of a display, it is currently widely used especially in portable devices. In recent years, portable devices such as mobile phones and personal digital assistants have grown remarkably, and visibility under sunlight and thinness and lightness have been strongly demanded. In a resistive touch panel, a fixed substrate with a transparent conductive layer and a movable substrate with a transparent conductive film are arranged via a space with the transparent conductive films facing each other. The position is detected by detecting the contact position or the resistance value when the transparent conductive films contact each other by pressing. Usually, the touch panel
Attached to the display surface. In this case, the air layer is 2
In this case, there is a problem that visibility is significantly reduced due to reflection at each air interface, and the device itself becomes thick. On the other hand, Japanese Patent Application Laid-Open No. 5-127822 and Monthly Display, January 1999, p. 69 propose an inner type touch panel in which the function of a resistive touch panel is inserted between a polarizing plate and a liquid crystal cell. . According to this method, the air layer becomes one layer, and furthermore, by combining the air layer with a λ / 4 plate, interfacial reflection is significantly reduced and visibility is improved. However, even if it is called a λ / 4 plate, most achieve λ / 4 at a specific wavelength, and its antireflection effect is not sufficient.

JP-A-5-27118 and JP-A-5-27118
No. 119 discloses a retardation plate in which a birefringent film having a large retardation and a birefringent film having a small retardation are laminated such that their optical axes are orthogonal to each other. If the retardation difference between the two films is λ / 4 over the entire visible light range, the retardation plate theoretically has λ over the entire visible light range.
/ 4. JP-A-10-68816 discloses that
A phase difference plate that can obtain λ / 4 in a wide wavelength region by laminating a polymer film having λ / 2 at a specific wavelength and a polymer film made of the same material and having λ / 4 at the same wavelength. Is disclosed. JP-A-10-90521 also discloses a retardation plate capable of achieving λ / 4 in a wide wavelength region by laminating two polymer films. As the above polymer films, two stretched films of a synthetic polymer such as polycarbonate were used, so that the thickness of the apparatus could not be reduced.

[0004] JP-A-2000-137116 discloses that
A broadband λ / 4 plate using one polymer film is disclosed. However, this λ / 4 plate has a problem that the film thickness is large. When used for a touch panel, the antireflection effect was not sufficient. JP 2000
Japanese Patent Publication No. 1126663 discloses a touch panel using a wideband λ / 4 plate, but the visibility is not sufficiently improved.

[0005] The reflective liquid crystal display device does not require a backlight and has low power consumption.
It is used as a display for portable devices such as portable game machines and mobile phones. 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. For the display mode of the liquid crystal cell,
TN (Twisted Nematic), STN (Supper Twisted Nem)
atic), HAN (Hybrid Aligned Nematic), HPDL
C (Holographic Polymer Dispersed Liquid Crysta
l), various display modes such as GH (Guest Host) have been proposed. TN mode reflective liquid crystal display devices
It has already been put to practical use. In a transmission type liquid crystal display device, two polarizing films are indispensable, but in a reflection type liquid crystal display device, λ / 4 is used.
By using a plate, an image can be displayed even with one polarizing film. When one polarizing film is reduced, light does not attenuate,
A bright image can be displayed. A reflection type liquid crystal display device having a λ / 4 plate is disclosed in JP-A-10-186357.
There is a description in the publication. It is also known that brighter display is possible when a guest-host (GH) mode liquid crystal cell is used in a reflective liquid crystal display device.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to apply a single polymer film which realizes λ / 4 over the entire visible light range to a touch panel. Another object of the present invention is to provide a reflective liquid crystal display device with a touch panel or a guest-host type liquid crystal display device with a touch panel, in which the display quality such as contrast and color is improved.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide the following touch panels (1) to (8) and the following touch panels (9) to (1).
This was achieved by the reflective liquid crystal display device of 1). (1) two transparent conductive substrates provided with a transparent conductive film on at least one side are arranged so that the transparent conductive films face each other, and at least one of the transparent conductive substrates is a λ / 4 plate; Alternatively, a touch panel in which a λ / 4 plate is laminated on a surface of at least one transparent conductive substrate,
The λ / 4 plate has a retardation value (Re450) measured at a wavelength of 450 nm of 100 to 125 nm and a retardation value (Re450) measured at a wavelength of 590 nm.
590) is from 120 to 160 nm, and Re590−
A touch panel comprising one piece of cellulose ester film satisfying a relationship of Re450 ≧ 2 nm.

(2) The cellulose ester film has a retardation value (Re45) measured at a wavelength of 450 nm.
0) is 108 to 120 nm, the retardation value (Re550) measured at a wavelength of 550 nm is 125 to 142 nm, the retardation value (Re590) measured at a wavelength of 590 nm is 130 to 152 nm, and Re590-Re550. The touch panel according to (1), which satisfies a relationship of ≧ 2 nm. (3) The cellulose ester film has an acetylation degree of 55.
The touch panel according to (1) or (2), which is a cellulose acetate film of 0 to 61.5%. (4) The film according to any one of (1) to (3), wherein the cellulose ester film is a film made of cellulose acetate having a 6-position substitution ratio of 30% or more and 40% or less. Touch panel. (5) Cellulose ester films include compounds having a molecular structure having at least two aromatic rings and having no steric hindrance to the conformation of the two aromatic rings (1) to (4).
The touch panel according to any one of the above.

(6) The cellulose ester film has a refractive index nx in the in-plane slow axis direction, a refractive index ny in the direction perpendicular to the slow axis in the plane, and a refractive index nz in the thickness direction of 1 ≦ 1.
The touch panel according to any one of (1) to (5), which satisfies a relationship of (nx-nz) / (nx-ny) ≦ 2. (7) A polarizing film is further laminated on the cellulose ester film side, and is arranged such that the angle between the in-plane slow axis of the cellulose ester film and the polarizing axis of the polarizing film is substantially 45 °. The touch panel according to any one of (1) to (6). (8) The touch panel according to any one of (1) to (7), wherein a transparent conductive film having a surface resistivity of 10 ⁴ Ω / □ or less is provided on at least one surface of the cellulose ester film.

(9) A reflection type liquid crystal display device comprising a polarizing film, a λ / 4 plate, a touch panel and a reflection type liquid crystal cell, wherein the λ / 4 plate has a retardation value (Re450) measured at a wavelength of 450 nm. A retardation value (Re590) measured at a wavelength of 590 nm of from 100 to 125 nm is from 120 to 160 nm;
A reflection type liquid crystal display device comprising one sheet of cellulose ester film satisfying a relationship of 90-Re450 ≧ 2 nm. (10) The reflective liquid crystal display device according to (9), in which a polarizing film, a λ / 4 plate, a touch panel, and a reflective liquid crystal cell are stacked in this order. (11) The reflective liquid crystal display device according to (9), wherein the touch panel and the reflective liquid crystal cell share one substrate, and the transparent electrode layers are provided on both surfaces of the shared substrate.

(12) A guest-host type liquid crystal display device comprising a λ / 4 plate, a touch panel and a guest-host type liquid crystal cell, wherein the λ / 4 plate has a retardation value (Re450) of 100 measured at a wavelength of 450 nm. To 125
a guest-host type liquid crystal comprising one sheet of cellulose ester film having a retardation value (Re590) measured at a wavelength of 590 nm of 120 to 160 nm and satisfying a relationship of Re590-Re450 ≧ 2 nm. Display device. (13) The guest-host type liquid crystal display device according to (12), wherein the λ / 4 plate, the touch panel, and the guest-host type liquid crystal cell are stacked in this order. (14) The guest-host type liquid crystal display device according to (12), wherein the touch panel and the guest-host type liquid crystal cell share a single substrate, and transparent electrode layers are provided on both surfaces of the shared substrate.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [λ / 4 plate] The λ / 4 plate has a wavelength of 4
Retardation value measured at 50 nm (Re450)
Is 100 to 125 nm, the retardation value (Re590) measured at a wavelength of 590 nm is 120 to 160 nm, and Re590-Re450
Satisfies the relationship of ≧ 2 nm. Re590-Re450 ≧
More preferably, the thickness is 5 nm.
Most preferably, 450 ≧ 10 nm. Wavelength 45
The retardation value (Re450) measured at 0 nm is 108 to 120 nm, and the retardation value (Re550) measured at a wavelength of 550 nm is 125 to 14
A retardation value (Re590) measured at a wavelength of 590 nm of 130 to 152 nm,
And it is preferable to satisfy the relationship of Re590-Re550 ≧ 2 nm. Re590-Re550 ≧ 5 nm
And more preferably Re590-Re550.
Most preferably, ≧ 10 nm. Also, Re55
It is also preferable that 0-Re450 ≧ 10 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 λ / 4 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 cellulose ester film constituting the λ / 4 plate is preferably from 5 to 1000 μm, more preferably from 10 to 500 μm, further preferably from 40 to 200 μm, Most preferably, it is 70 to 120 μm.

[Cellulose ester] In the present invention, λ /
One sheet of cellulose ester film is used as four plates. As the cellulose ester, a lower fatty acid ester of cellulose is preferable. The lower fatty acid means a fatty acid having 6 or less carbon atoms. The number of carbon atoms is 2 (cellulose acetate), 3 (cellulose propionate)
Alternatively, it is preferably 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 acetylation degree (acetylation degree) of cellulose acetate is
It is preferably from 55.0 to 61.5%.
More preferably, it is 0 to 60.5%. In general, the 2,3,6 hydroxyl groups of cellulose acylate are not evenly distributed to 1/3 of the total degree of substitution, and the degree of substitution of the 6-position hydroxyl group tends to decrease. In the present invention, the substitution degree of the 6-position hydroxyl group of cellulose acylate is
It is more preferable to have more than the second and third positions. Preferably, the hydroxyl group at the 6-position is substituted with an acyl group in an amount of 30% or more and 40% or less with respect to the total degree of substitution, and more preferably 31% or more
In particular, it is preferably at least 32%. Further, the substitution degree of the 6-position acyl group of cellulose acylate is preferably 0.88 or more. The 6-position hydroxyl group may be substituted with an acyl group having 3 or more carbon atoms, such as a propionyl group, a butyroyl group, a valeroyl group, a benzoyl group, and an acryloyl group, in addition to the acetyl group. The degree of substitution at each position can be determined by NMR. As the cellulose acylate of the present invention, Synthesis Example 1 described in paragraphs 0043 to 0044 of JP-A-11-5851, Synthesis Example 2 described in paragraphs 0048 to 0049, and synthesis described in paragraphs 0051 to 0052 The cellulose acetate obtained by the method of Example 3 can be used.

[Retardation raising agent] In order to adjust the retardation value at each wavelength, a retardation raising agent can be added to the cellulose ester film. The retardation increasing agent is preferably used in an amount of 0.05 to 20 parts by mass, more preferably 0.1 to 10 parts by mass, and more preferably 0.1 to 10 parts by mass, based on 100 parts by mass of the cellulose ester. It is more preferably used in the range of 2 to 5 parts by mass, and most preferably used in the range of 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. 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 preferable.

The number of aromatic rings contained in the retardation increasing agent is preferably from 2 to 20, preferably from 2 to 12.
Is more preferably, 2 to 8 is more preferable, and 2 to 6 is most preferable. 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 is (a)-
Any of (c) may be used.

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.
JP-A-111914, JP-A-2000-275434, and PCT / JP00 / 02619.

[Infrared absorber] In order to adjust the retardation value at each wavelength, an infrared absorber can be added to the cellulose ester film. The infrared absorber is used in an amount of 0.1 to 100 parts by mass of the cellulose ester.
It is preferably used in the range of 01 to 5 parts by mass,
It is more preferably used in the range of 0.02 to 2 parts by mass, further preferably used in the range of 0.05 to 1 part by mass, and used in the range of 0.1 to 0.5 part by mass. Most preferred. Two or more infrared absorbers may be used in combination. The infrared absorbing agent is 750 to 1100n
m preferably has a maximum absorption in the wavelength region of
More preferably, it has maximum absorption in the wavelength region of 0 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 Cellulose Ester Film] It is preferable to produce a cellulose ester 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. Organic solvents have 3 carbon atoms.
It is preferable to include a solvent selected from ethers having 1 to 12 carbon atoms, 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. Compounds 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 is
It 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 cellulose ester 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 addition,
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 cellulose ester is 10
It is adjusted to be contained in an amount of from 40 to 40% by mass. More preferably, the amount of the cellulose ester is 10 to 30% by mass. In the organic solvent (main solvent), any additives described below may be added. The solution can be prepared by stirring the cellulose ester 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 cellulose ester and the organic solvent are put in a pressurized container, sealed, and 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 the cooling dissolution method. In the cooling dissolution method, the cellulose ester 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 the cellulose ester by the 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 cellulose ester is gradually added to an organic solvent at room temperature while stirring. The amount of the cellulose ester is preferably adjusted so as to be contained in the mixture at 10 to 40% by mass. More preferably, the amount of the cellulose ester is 10 to 30% by mass. Further, an optional additive described below may be added to the mixture.

Next, the mixture is cooled 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 the cellulose ester and the organic solvent solidifies. The cooling rate is preferably 4 ° C./min or more, more preferably 8 ° C./min or more, and 12 ° C./min.
/ Min or more is most preferable. A higher cooling rate is preferred, but 10,000 ° C./sec is the theoretical upper limit, 1000 ° C./sec is the technical upper limit, and
0 ° 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,
When heated to (most preferably 0 to 50 ° C.), the cellulose ester dissolves in the organic solvent. The temperature may be raised only by leaving it at room temperature or may be heated in a warm bath. The heating rate is preferably 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 high as possible, but the theoretical upper limit is 10,000 ° C./sec.
C / sec is a technical upper limit, and 100 C / sec is a 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. In addition,
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 and dissolving method, it is preferable to use a closed container in order to avoid mixing of water 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 cellulose ester solution (dope), a cellulose ester 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 U.S. Pat. Nos. 2,336,310 and 2,367,603.
Nos. 2492078, 2492977, 24
No. 92978, No. 2607704, No. 2739069
Nos. 2739070, British Patent Nos. 640731 and 736892, Japanese Patent Publication No. 45-4554,
JP-A-49-5614, JP-A-60-176834, 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 can be peeled off from the drum or band, and further dried with high-temperature air whose temperature is gradually changed from 100 to 160 ° C. to evaporate the residual solvent. The above method is described in JP-B-5-17844. 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 produced is preferably 40 to 120 μm,
More preferably, it is 70 to 100 μm.

[Plasticizer] A plasticizer can be added to the cellulose ester film in order to improve mechanical properties or to increase the drying speed. As the plasticizer, a phosphoric acid ester or a carboxylic acid ester is used. Examples of phosphate esters include triphenyl phosphate (TPP) and tricresyl phosphate (TCP). As the carboxylic acid ester,
Phthalates and citrates are typical. Examples of phthalic acid esters include dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), and dioctyl phthalate (DO).
P), diphenyl phthalate (DPP) and diethylhexyl phthalate (DEHP). Examples of citrate esters include O-acetyl triethyl citrate (OACTE) and O-acetyl tributyl citrate (OACTB). Examples of other carboxylic esters include butyl oleate, methylacetyl ricinoleate, dibutyl sebacate, and various trimellitic esters. Phthalate ester plasticizer (DM
P, DEP, DBP, DOP, DPP, DEHP) are preferably used. DEP and DPP are particularly preferred. The amount of the plasticizer added is 0.1 to 25 times the amount of the polymer.
%, More preferably 1 to 20% by mass, most preferably 3 to 15% by mass.

[Deterioration inhibitor] A cellulose ester film is added with a degradation inhibitor (eg, an antioxidant, a peroxide decomposer, a radical inhibitor, a metal deactivator, an acid scavenger, an amine). Is also good. As for the deterioration inhibitor, JP-A-3-199201, JP-A-5-1907073, and JP-A-5-1907073.
194789, 5-271471, 6-107
It is described in each publication of No. 854. 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. If the amount exceeds 1% by mass, bleed out (bleeding out) of the deterioration inhibitor on the film surface may be observed. Examples of particularly preferred deterioration inhibitors include butylated hydroxytoluene (BHT) and tribenzylamine (T
BA).

[Stretching Treatment] The cellulose ester film is further subjected to a stretching treatment to obtain a refractive index (refractive index nx in the in-plane slow axis direction, refractive index ny in the direction perpendicular to the in-plane slow axis, and refraction in the thickness direction). It is preferable to adjust the ratio nz). When the intrinsic birefringence is positive, the refractive index increases in the direction in which the polymer chains are oriented. When a polymer having such 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. Thereby, 1 ≦ (nx−nz)
/ (Nx-ny) can be satisfied. Further, in order to satisfy the relationship of (nx−nz) / (nx−ny) ≦ 2, it is necessary to control the stretching ratio of uniaxial stretching or adjust the refractive index by performing unbalanced biaxial stretching. I just need. Specifically, the maximum stretching ratio SA and the stretching ratio SB in the direction perpendicular to the stretching direction are 1 <SA / S
Uniaxial stretching or unbalanced biaxial stretching may be performed so as to satisfy the relationship of B ≦ 3. 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, shrink). If the relationship of the above expression is satisfied, SB may be a value less than 1. Further, the stretching ratio is adjusted so that the front retardation becomes λ / 4. The stretching process may be a simultaneous process or a sequential process.

[Circularly Polarizing Plate] A λ / 4 plate and a 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 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 °, more preferably 42 to 48 °, and 43 to 47 °. Is more preferable, and most preferably 44 to 46 °. The 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-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 a hard coat layer on the transparent protective film. It is preferable to provide an anti-reflection layer as the outermost layer.

[Touch Panel] The touch panel includes a fixed substrate near the display element and a movable substrate facing the display device. A transparent electrode is provided on each of the opposing surfaces of the fixed substrate and the movable substrate. It is preferable that the fixed substrate and the movable substrate are formed of a transparent optical material in order to improve display quality. Materials used for the fixed substrate and the movable substrate include:
For example, glass, amorphous film, polyethersulfone, polycarbonate, polyarylate, polyethylene terephthalate, polymer film such as cellulose ester and the like can be mentioned. The λ / 4 plate made of the cellulose ester film used in the present invention may be provided separately from the touch panel, or may be used for one or both of the fixed substrate and the movable substrate. It is particularly preferable to use a λ / 4 plate made of a cellulose ester film as a movable substrate. A gap is formed between the two transparent electrodes. An air layer is usually present between the gaps, but a liquid having a refractive index close to that of the transparent electrode can be filled for optical matching. Also, an undercoat layer on the substrate side of the transparent electrode film, or
An overcoat layer may be provided on the side opposite to the substrate to reduce light reflection. The surface of the transparent electrode film may be roughened in order to eliminate sticking and improve the keying life. Spacers can be provided between the gaps. As the spacer, a dot-shaped spacer, a bonding material provided around the fixed substrate and the movable substrate, or the like is used.

The touch panel is used as either a digital type or an analog type. In the digital type, it is possible to detect the contact between the transparent electrodes by pressing and the data position corresponding to the contact position. In the analog type, for example, electrodes are formed at both ends of the fixed substrate in the X-axis direction and both ends of the movable substrate in the Y-axis direction. The data input position can be detected by detecting the resistance value in the direction. In the present invention, the touch panel is preferably used together with a display element. The touch panel unit may be separate from the display unit, or both may be integrated. When the touch panel is used together with the polarizing plate, the polarizing plate may be provided between the touch panel and the display element, or the polarizing plate may be an inner type provided outside the touch panel (on the observer side). In the present invention, it is preferable to use the inner type because the reflection of external light can be reduced and the anti-glare property is excellent.

[Transparent Conductive Film] As the transparent conductive film used as the touch panel, the surface resistivity is preferably 10 ⁴ Ω / □ or less, more preferably 1000 Ω / □ or less, and more preferably 500 Ω / □ or less. Most preferably. It is particularly preferable to provide a transparent conductive film on at least one surface of the λ / 4 plate made of cellulose ester used in the present invention and use it as an inner type touch panel.

In order to set the surface resistivity of the transparent conductive film to the above value, it may be provided by applying a dispersion of conductive fine particles or by co-casting at the time of film casting. Absent. Further, a transparent conductive film may be formed by a vacuum film forming method such as sputtering, vacuum evaporation, or ion plating. A transparent conductive film may be provided on one side of the film, or may be provided on both sides. Also, these methods can be used in combination.

The method of applying the conductive fine particle dispersion basically comprises a layer containing at least one kind of metal and / or fine particles made of metal oxide or metal nitride. As fine particles composed of one or more metals,
Metals such as gold, silver, copper, aluminum, iron, nickel, palladium, platinum and the like, or alloys thereof. Particularly, silver is preferable, and an alloy of palladium and silver is more preferable from the viewpoint of weather resistance. The content of palladium is preferably 5 to 30% by weight. When the amount of palladium is small, the weather resistance is poor, and when the amount of palladium is large, the conductivity is reduced. Examples of the method for preparing metal fine particles include a method for preparing fine particles by a low vacuum evaporation method and a method for preparing a metal colloid in which an aqueous solution of a metal salt is reduced with a reducing agent such as iron (II), hydrazine, boron hydride, or hydroxyethylamine. No. As a metal oxide, In ₂ O ₃ (Sn
Such as including doped product), including SnO ₂ system (F, Sb, etc. doped product), ZnO-based (Al, including doped products such as _{Ga), TiO 2, Al 2} O 3, SiO 2, MgO, Ba
O, MoO ₃ , V ₂ O ₅ , or a composite thereof, and the like. Examples of the metal nitride include TiN.

The average particle diameter of these conductive fine particles is 1.0 to
700 nm is preferable, 2.0 to 300 nm is more preferable, and 5.0 to 100 nm is most preferable. If the particle size is too large, light absorption by the conductive fine particles increases,
For this reason, the haze increases at the same time as the light transmittance of the particle layer decreases, and when the average particle diameter of these conductive fine particles is less than 1 nm, dispersion of the fine particles becomes difficult,
Since the surface resistance of the fine particle layer rapidly increases, it is not possible to obtain a coating having a low resistance enough to achieve the object of the present invention.

The conductive fine particle layer can be formed by applying a coating solution in which conductive fine particles are dispersed in a solution mainly composed of water or an organic solvent or the like. Before application, surface treatment or undercoating can be applied. As the surface treatment,
For example, a corona discharge treatment, a glow discharge treatment, a chromic acid treatment (wet method), a flame treatment, a hot air treatment, an ozone / ultraviolet irradiation treatment and the like can be mentioned. Examples of the material for the undercoat layer include, but are not particularly limited to, copolymers such as vinyl chloride, vinylidene chloride, butadiene, (meth) acrylate, and vinyl ester, and water-soluble polymers such as latex and gelatin. For stabilizing the dispersion of the conductive fine particles, a solution mainly composed of water is preferable, and as a solvent that can be mixed with water, ethyl alcohol, n-propyl alcohol,
Alcohols such as i-propyl alcohol, butyl alcohol, methyl cellosolve and butyl cellosolve are preferred. The application amount of the conductive fine particles is 10 to 1000
mg / m ² is preferable, 20 to 500 mg / m ² is more preferable, and 50 to 150 mg / m ² is most preferable. If the coating amount is small, the conductivity cannot be obtained, and if the coating amount is large, the transmittance is poor.

The transparent conductive layer may contain a binder or may not contain a binder and may be formed substantially only of conductive fine particles. When a binder is used, the material is not particularly limited, but a hydrophilic binder, a hydrophobic binder, or latex can be used. As the hydrophilic binder, gelatin, gelatin derivatives, agar, sodium alginate, starch, polyvinyl alcohol, polyacrylic acid copolymer,
Maleic anhydride copolymer, carboxymethyl cellulose, carboxyethyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose and the like. As the hydrophobic binder, cellulose esters (for example, nitrocellulose, diacetylcellulose, triacetylcellulose, methylcellulose), vinyl chloride,
Vinyl-based polymers including vinylidene chloride and vinyl acrylate, and polymers such as polyamide and polyester.

Heat treatment or water treatment can be performed to improve the conductivity and transparency of the transparent conductive layer. The heat treatment depends on the heat resistance of the polymer film, but is preferably 150 ° C. or lower. 100 ° C to 150 ° C is preferred. Above 150 ° C, the polymer film is likely to be deformed by heat,
If the temperature is lower than 100 ° C., the effect of the heat treatment is hardly obtained, and a long processing time is required. As the heat treatment method, it is preferable to perform the treatment while passing through the heating zone in a web state, since uniform treatment can be performed. The stay time can be adjusted by the length of the heating zone and the transport speed. It is also possible to heat the rolled film in a thermostat, but it is necessary to set the time in consideration of the variation in heat conduction.

Further, prior to the heat treatment, the heat treatment can be made more efficient by subjecting the transparent conductive layer to a water treatment such as washing with water. Water treatment such as water washing includes application of only water by a normal application method, specifically, dip coating, application of water by a wire bar, and the like. In addition, water is applied to the transparent conductive layer by spraying or showering. There is a way. After water is applied to the transparent conductive layer, excess water can be scraped off with a wire bar or a rod bar or with an air knife as necessary. By these water treatments, the surface resistance of the transparent conductive tank after the heat treatment can be further reduced, and in addition, the transmittance is increased, the transmission spectrum is flattened, and the reflectance is reduced after the antireflection layer is laminated. The effect becomes remarkable.

As the vacuum film forming method, a method described in "New Development of Transparent Conductive Film", supervised by CMC and Yutaka Sawada, "Monthly Display", September 1999, can be used. As the metal oxide to be formed, In ₂ O ₃ -based (including doped products such as Sn and ITO), SnO ₂ -based (including doped products such as F and Sb), ZnO-based (including doped products such as Al and Ga) or these And a composite product of In ₂ O ₃ —ZnO type. Examples of the metal nitride include TiN. Further, a film may be formed together with silver or the like.

When a film is formed on a polymer film by sputtering or the like, the surface thereof is made of a fluororesin, an acrylic resin,
Polymers such as silicon-based resin, propylene-based resin, and vinyl-based resin, and SiO ₂ , TiO ₂ , ZrO ₂ , and SnO ₂
It is preferable to coat with an inorganic substance such as. The coating thickness is preferably 10 nm or more and 100 μm or less,
It is more preferably 10 nm or more and 50 μm or less, particularly preferably 10 nm or more and 10 μm or less. It is preferable to cool the substrate during sputtering or the like. It is preferably -30 ° C or more and 30 ° C or less, more preferably -30 ° C or more and 20 ° C or less, and particularly preferably -30 ° C or less.
It is not less than 10 ° C and not less than 10 ° C. As a method for forming a film mainly containing indium oxide by a sputtering method, reactive sputtering using a metal target containing indium as a main component or a target which is a sintered body mainly containing indium oxide is used. it can. The latter is preferred for controlling the reaction. In the reactive sputtering method, an inert gas such as argon is used as a sputtering gas, and oxygen is used as a reactive gas. As a discharge type, DC magnetron sputtering, RF magnetron sputtering, or the like can be used. As a method for controlling the flow rate of oxygen, it is preferable to use a plasma emission monitor method.

The light transmittance of the polymer film provided with the transparent conductive layer is preferably 50% or more.
%, More preferably 70% or more, and most preferably 80% or more.

[Reflective Liquid Crystal Display Device] The touch panel of the present invention can be used in combination with various display devices. For example, cathode ray tube (CRT), plasma display (PDP), field emission display (FED), inorganic EL device, organic E
L device, liquid crystal display device, and the like. 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), a liquid crystal layer (4), an upper alignment film (5), and 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.

FIG. 2 is a schematic diagram showing a basic configuration of a reflection type liquid crystal display device using a touch panel. The reflection-type liquid crystal display device using the touch panel shown in FIG. , A transparent electrode (6), an upper substrate (7), a transparent conductive film (10), a transparent conductive film (11), a λ / 4 plate (8), and a polarizing film (9). A gap is formed between the transparent conductive film (10) and the transparent conductive film (11), and functions as a touch panel.

Although the liquid crystal mode to be used is not particularly limited, a TN (twisted nematic) type, STN (Supper Twisted
sted Nematic) type, HAN (Hybrid Aligned Nematic)
It is preferable to use a GH (Guest Host) type. The twist angle of the TN type liquid crystal cell is preferably from 40 to 100 °, more preferably from 50 to 90 °, and most preferably from 60 to 80 °. 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 0.5 μm
Is preferably, and more preferably, 0.2 to 0.4 μm. The twist angle of the STN liquid crystal cell is preferably 180 to 360 °,
It is more preferable that the angle is from about 270 ° to 270 °. The product (Δn) of the refractive index anisotropy (Δn) of the liquid crystal layer and the thickness (d) of the liquid crystal layer
The value of d) is preferably 0.3 to 1.2 μm, and 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 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 1.0 μm,
More preferably, it is 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.

In the GH type liquid crystal cell, the liquid crystal layer is composed of a mixture of a liquid crystal and a dichroic dye. When both the liquid crystal and the dichroic dye are rod-shaped compounds, the director of the liquid crystal and the long axis direction of the dichroic dye are parallel. When the orientation state of the liquid crystal changes due to the application of a voltage, the long axis direction of the dichroic dye changes similarly to the liquid crystal. GH type liquid crystal cells include Heilmeir type,
White-Taylor using cholesteric liquid crystal
Although a mold, a two-layer type, and a method using a λ / 4 plate are known, in the present invention, it is preferable to use a method using a λ / 4 plate. Japanese Patent Application Laid-Open Nos. Hei 6-222350, Hei 8-36174, Hei 10-268300, and Hei 10-268
No. 292175, No. 10-293301, No. 10-3
No. 11976, No. 10-319442, No. 10-32
No. 5953, No. 10-333138, No. 11-384
There is a description in each publication of No. The λ / 4 plate is provided between the liquid crystal layer and the reflection plate. The liquid crystal layer may use either horizontal alignment or vertical alignment, but it is preferable to use vertical alignment. The dielectric anisotropy of the liquid crystal is preferably negative. 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. . Normally white mode is preferred.

[0059]

[Example 1] (Preparation of λ / 4 plate) At room temperature, average acetylation degree 59.7
% Cellulose acetate, 1.2 parts by mass of the following retardation raising agent, 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;
8 parts by mass were mixed to prepare a solution (dope).

[0060]

Embedded image

The obtained dope was cast on a stainless steel band, and the film was dried until it had a self-supporting property, and then was peeled off from the band. The residual volatile matter at that time was 30% by mass. Thereafter, the film was dried at 120 ° C. for 15 minutes to reduce the residual volatile content 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 film thus obtained is 108 μm.
m.

The obtained cellulose acetate film (λ / 4 plate) was subjected to an ellipsometer (M-15).
0, manufactured by JASCO Corporation, wavelength 450 nm, 5
When the retardation values (Re) at 50 nm and 590 nm were measured, each was 121.2 n.
m, 137.5 nm, and 142.7 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 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−nz) / (n
The value of (x-ny) was calculated to be 1.50.

(Production of Reflective Liquid Crystal Display Device with Touch Panel) A reflective liquid crystal display device with a touch panel using a TN type liquid crystal cell (Saurus Color Pocket MI-31)
0, manufactured by Sharp Corporation), and the λ / 4 plate and the polarizing plate prepared in Example 1 were peeled off in place of the polarizing plate and the retardation plate. Pasted. The angle between the stretching direction of λ / 4 (parallel to the slow axis direction) and the transmission axis direction of the polarizing plate was 45 °. About the manufactured liquid crystal display device, a measuring device (EZ-Contrast 160D,
When the contrast ratio was measured using ELDIM, it was 10: 1 at the front. When the viewing angle at which a contrast ratio of 2: 1 was obtained in the upper, lower, left and right directions was measured, it was 120 ° or more in both the upper, lower, left and right directions.

[Comparative Example 1] Using a TN type liquid crystal cell,
Regarding the reflective liquid crystal display device with touch panel (Saurus Color Pocket MI-310, manufactured by Sharp Corporation)
The contrast ratio was measured using a measuring machine (EZ-Contrast 160D, manufactured by ELDIM).
0: 1. In addition, the contrast ratio is 2:
When the viewing angle at which 1 was obtained was measured, the vertical angle was 100 °,
It was 90 ° left and right.

[Example 2] (Production of reflective liquid crystal display device with touch panel) ITO
On a glass substrate provided with a transparent electrode, a solution of a polymer for forming a vertical alignment film (LQ-1800, manufactured by Hitachi Chemical DuPont Microsystems) was applied, dried, and then rubbed. The λ / 4 plate produced in Example 1 was adhered on a glass substrate on which aluminum was vapor-deposited as a reflection plate with an adhesive. An SiO layer was provided on the λ / 4 plate by sputtering, and an ITO transparent electrode was provided thereon. On the transparent electrode, a polymer for forming a vertical alignment film (LQ-180)
0, manufactured by Hitachi Chemical DuPont Microsystems Co., Ltd.), dried, and then rubbed in a direction of 45 ° from the slow axis direction of the λ / 4 plate. Two glass substrates were stacked via a 7.6 μm spacer such that the alignment films faced each other. The orientation of the substrate was adjusted so that the rubbing direction of the alignment film was antiparallel. 2.5% by mass of dichroic dye (NKX-1366, manufactured by Nippon Kogaku Dye Co., Ltd.)
And a liquid crystal (ZLI-2806, manufactured by Merck) at 97.5% by mass was injected by a vacuum injection method to form a liquid crystal layer. The touch panel used in Example 1 was provided on the observer side of the manufactured guest-host reflective liquid crystal display element. A rectangular wave voltage of 1 kHz was applied between the ITO electrodes of the manufactured guest-host reflection type liquid crystal display device. The reflectance at white display 1 V and black display 10 V was 65% and 6%, respectively. Ratio of reflectance between white display and black display (contrast ratio)
Was 11: 1. When the viewing angle at which a contrast ratio of 2: 1 was obtained in the upper, lower, left and right directions was measured, it was 120 ° or more in both the upper, lower, left and right directions. The reflectance was measured while increasing and decreasing the voltage, but no hysteresis was observed in the reflectance-voltage curve.

Example 3 (Preparation of λ / 4 Plate) A stretched film was prepared in the same manner as in Example 1, and a transparent conductive film was applied as follows.

[0067] 1) Preparation of silver-palladium colloidal dispersion prepared 30% iron sulfate _{(II) FeSO 4 · 7H 2} O, 40% citric acid (Coating of the transparent conductive film), mixed, held at 20 ° C., While stirring, 10% silver nitrate and palladium nitrate (9/1 molar ratio)
The solution was added and mixed at a rate of 200 ml / min, and thereafter, washing with water was repeated by the generated centrifugal separation, and pure water was finally added to a concentration of 3% by mass to prepare a silver-palladium colloidal dispersion. . As a result of TEM observation, the particle diameter of the obtained silver colloid particles was about 9 to 12 nm.
Met. As a result of measurement by ICP, the ratio of silver to palladium was the same as the charging ratio of 9/1.

2) Preparation of Silver Colloid Coating Solution To 100 g of the silver colloid dispersion solution, i-propyl alcohol was added, ultrasonically dispersed, and filtered through a polypropylene filter having a pore size of 1 μm to prepare a coating solution.

3) Preparation of Coating Solution L-1 for Overcoating A mixture (DPH) of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate
A, 2 g of Nippon Kayaku Co., Ltd., 80 mg of photopolymerization initiator (Irgacure 907, Ciba-Geigy) and 30 m of photosensitizer (Kayacure DETX, Nippon Kayaku Co., Ltd.)
g was added to and dissolved in a mixed solution of 38 g of methyl isopropyl ketone, 38 g of 2-butanol and 19 g of methanol.
After stirring the mixture for 30 minutes, it was filtered through a polypropylene filter having a pore size of 1 μm to prepare a coating solution for overcoating.

4) Formation of Transparent Conductive Laminate After applying a corona treatment to the stretched film, the above-mentioned silver colloid coating solution was applied using a wire bar so that the coating amount was 70 mg / m ² , and dried at 40 ° C. Water fed by a pump was sprayed on the silver colloid-coated surface, excess water was removed with an air knife, and a treatment was carried out for 5 minutes while transporting in a heating zone at 120 ° C. Next, the overcoat coating liquid L-1 was applied to a thickness of 80 nm, dried, and heat-treated at 120 ° C. for 2 hours, and then irradiated with ultraviolet rays to cure the coating film.

The thickness of the film thus obtained was 102 μm. The surface resistivity of the transparent conductive film was measured by a four-terminal method, and as a result, it was 400 Ω / □.
The light transmittance was 71%. The obtained cellulose acetate film (λ / 4) was analyzed using an ellipsometer (M-150, manufactured by JASCO Corporation) at a wavelength of 4
When the retardation values (Re) at 50 nm, 550 nm, and 590 nm were measured,
It was 116.4 nm, 132.0 nm, and 137.0 nm. Therefore, this cellulose acetate film achieved λ / 4 in a wide wavelength range. Further, the refractive index nx in the in-plane slow axis direction at a wavelength of 550 nm and the refractive index in the direction perpendicular to the slow axis in the plane at a wavelength of 550 nm were measured from the refractive index measurement using an Abbe refractometer and the measurement of the angle dependence of the retardation. ny and the refractive index nz in the thickness direction are obtained, and (nx−
When the value of (nz) / (nx-ny) was calculated, 1.5
It was 2.

(Preparation of Touch Panel) A glass plate having a thickness of 0.7 mm provided with a transparent conductive film (ITO) having a surface resistivity of 5 Ω / □ on one side and a surface resistivity of 400 Ω / □ on the other side was prepared. A polyimide alignment film (SE-7992, manufactured by Nissan Chemical Industries, Ltd.) was formed on a surface having a surface resistivity of 5Ω / □, and rubbing treatment was performed. The other side (surface resistivity 400
Ω / □), dot spacers of 1 mm pitch and silver electrodes were printed on both ends. Silver electrodes were printed on both ends of the obtained λ / 4 plate with a transparent conductive film, and bonded to the transparent conductive glass plate so that the transparent conductive films faced each other. At this time, an insulating bonding agent having a thickness of 100 μm was sandwiched around both substrates. The λ /
AR-treated polarizing plates were attached to the four plates. λ /
The angle between the stretching direction (parallel to the slow axis direction) and the transmission axis direction of the polarizing plate was 45 °. Thus, a touch panel was manufactured.

(Production of Reflective Liquid Crystal Display Device) A glass substrate provided with an aluminum reflective electrode having fine irregularities was prepared. A polyimide alignment film (SE-7992, manufactured by Nissan Chemical Industries, Ltd.) was formed on the electrode side of the glass substrate,
A rubbing treatment was performed. The touch panel and the glass substrate provided with the reflective electrode were overlapped 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 °. In the gap between the substrates, a liquid crystal (MLC-6
252, manufactured by Merck & Co., Inc.) to form a liquid crystal layer. Thus, the twist angle is 70 ° and the value of Δnd is 26
A 9 nm TN liquid crystal cell was produced. In this way,
A reflection type liquid crystal display device using a touch panel was manufactured.
It was confirmed that the prepared touch panel operated well. A rectangular wave voltage of 1 kHz was applied to the manufactured reflective liquid crystal display device. Visual evaluation was performed with a white display of 1.5 V and a black display of 4.5 V. In both white display and black display, the reflective liquid crystal display device had no color and displayed neutral gray. Was confirmed. Next, when the contrast ratio of the reflection luminance was measured using a measuring device (EZcontrast 160D, manufactured by Eldim), the contrast ratio from the front was 25, and the contrast ratio was 2
Was 120 ° or more vertically and 120 ° or more horizontally.

Example 4 (Preparation of λ / 4 Plate) A stretched film was prepared in the same manner as in Example 1, and a transparent conductive film was applied as follows.

(Application of Transparent Conductive Film) 1) A UV-curable polyfunctional methacrylic resin (Z7503 manufactured by JSR) was applied to a thickness of 3 μm on an ITO sputtering stretched film on a cellulose triacetate film. Next, a 15 nm-thick ITO film was formed by DC magnetron sputtering.

The thickness of the film thus obtained was 103 μm. The surface resistivity of the transparent conductive film was measured by a four-terminal method and found to be 230 Ω / □.
The light transmittance was 89%. The obtained cellulose acetate film (λ / 4 plate) was measured for a retardation value (Re) at a wavelength of 450 nm, 550 nm, and 590 nm using an ellipsometer (M-150, manufactured by JASCO Corporation). , Respectively, 119.0 nm, 135.1 nm, 140.1 nm
Met. Therefore, this cellulose acetate film achieved λ / 4 in a wide wavelength range. further,
From the refractive index measurement with the Abbe refractometer and the measurement of the angle dependence of the retardation, the refractive index nx in the in-plane slow axis direction at a wavelength of 550 nm, the refractive index ny in the direction perpendicular to the in-plane slow axis, and The refractive index nz in the thickness direction is obtained, and (n
When the value of (x-nz) / (nx-ny) was calculated,
1.51.

(Preparation of Reflective Liquid Crystal Display Device with Touch Panel) A reflective liquid crystal display device with a touch panel was prepared in exactly the same manner as in Example 3 except that the thus obtained λ / 4 plate was used. . The created touch panel
It confirmed that it works well. A rectangular wave voltage of 1 kHz was applied to the manufactured reflective liquid crystal display device. White display 1.
Visual evaluation was performed at 5 V and a black display of 4.5 V, and it was confirmed that the reflective liquid crystal display had no color and displayed neutral gray in both white display and black display. . Next, a measuring machine (EZcontra
The contrast ratio of the reflected luminance was measured using a st160D (manufactured by Eldim), and the contrast ratio from the front was 28.
20 ° or more, left and right 120 ° or more.

Example 5 The composition shown below was charged into a mixing tank and cooled and dissolved (-70 ° C.) to prepare a cellulose acetate solution (dope). The method of casting on a stainless steel band was the same as in [Example 1]. The cellulose triacetate used here had an acetylation degree of 60.9.
%, Substitution degree 2.82, viscosity average degree of polymerization 320, water content 0.4 mass%, viscosity of 305 mPa · s of 6 mass% in methylene chloride solution, average particle diameter 1.5 mm, standard deviation 0.5 mm The residual acetic acid amount was 0.01% by mass or less, Ca was 0.05% by mass, Mg was 0.007% by mass, and Fe was 5 ppm. The 6-position acetyl group was 0.95, which was 32.2% of the total acetyl. The acetone extractables were 11% by mass, the ratio of the weight average molecular weight to the number average molecular weight was 0.5, and the distribution was uniform. The yellowness index is 0.
3, haze is 0.08%, transparency is 93.5%,
The Tg was 160 ° C., and the heat of crystallization was 6.2 J / g.

[0079]

[Table 1]

[0080] (Formation of a transparent conductive film) by setting the stretched film in a sputtering device of the film winding type prepared in Example 5, after the vacuum chamber was evacuated to a pressure of 1.2 mPa, Ar + O ₂ mixed gas (O ₂ = 1.5%), and the pressure was adjusted to 0.25 Pa.
DC sputtering was performed at a temperature of 1 ° C. and a power density of 1 W / cm ² to form a 21-nm-thick In ₂ O ₃ -based transparent conductive film. The thickness of the film thus obtained was 103 μm. The surface resistivity of the transparent conductive film was measured by a four-terminal method and found to be 406 Ω / □.
The light transmittance was 88%. Using an ellipsometer (M-150, manufactured by JASCO Corporation), a wavelength of 450 nm, 550 nm, and
Values at 590 and 590 nm (Re)
Of 118.0 nm and 13 respectively.
It was 4.0 nm and 136.0 nm. Therefore, this cellulose acetate film has a λ /
4 had been achieved. Furthermore, from the refractive index measurement by Abbe refractometer and the measurement of the angle dependence of the retardation,
Refractive index n in the in-plane slow axis direction at a wavelength of 550 nm
x, the refractive index ny in the direction perpendicular to the in-plane slow axis and the refractive index nz in the thickness direction are obtained, and (nx−nz) / (nx−n)
The value of y) was calculated to be 1.53.

(Preparation of Touch Panel and Reflection Type Liquid Crystal Display) A touch panel and a reflection type liquid crystal display were prepared in exactly the same manner as in Example 3 except that the λ / 4 plate thus obtained was used. Produced. It was confirmed that the touch panel manufactured in this manner operated well. A rectangular wave voltage of 1 kHz was applied to the manufactured reflective liquid crystal display device. Visual evaluation was performed with a white display of 1.5 V and a black display of 4.5 V. In both white display and black display, the reflective liquid crystal display device had no color and displayed neutral gray. Was confirmed. Next, the contrast ratio of the reflected luminance was measured using a measuring instrument (EZcontrast160D, manufactured by Eldim). It was 120 ° or more.

[0082]

As is clear from the above embodiments, the touch panel of the present invention operates well. In addition, by using the touch panel of the present invention, display quality such as contrast and color of the reflective liquid crystal display device is improved, and visibility is improved.

[Brief description of the drawings]

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

FIG. 2 is a schematic diagram showing a basic configuration of a reflective liquid crystal display device using a touch panel.

[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 10 transparent conductive film 11 transparent conductive film

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G02F 1/137 500 G02F 1/137 500 5G435 G09F 9/00 366 G09F 9/00 366A F-term (Reference) 2H088 GA13 HA02 HA17 HA18 HA21 JA06 KA07 MA02 MA05 2H089 HA18 HA24 HA25 RA06 TA02 TA15 TA17 2H091 FA08X FA08Z FA11X FB02 FD01 GA03 HA08 LA17 LA20 2H092 GA62 NA01 PA02 PA10 PA11 PA12 QA08 5B087 AA02 CC04 A02CC04 CC04 CC02 CC05 HH02 HH12

Claims (14)

[Claims] 1. Two transparent conductive substrates provided with a transparent conductive film on at least one side are disposed so that the transparent conductive films face each other, and at least one of the transparent conductive substrates is λ.
A λ / 4 plate, or a λ / 4 plate laminated on the surface of at least one transparent conductive substrate, wherein the λ / 4 plate has a retardation value (Re450) measured at a wavelength of 450 nm. A retardation value (Re590) measured at a wavelength of 590 nm of from 100 to 125 nm is from 120 to 160 nm;
590-Re450 ≧ 2 nm, a touch panel comprising a single cellulose ester film. 2. A cellulose ester film having a wavelength of 4
Retardation value measured at 50 nm (Re450)
Is from 108 to 120 nm, and the retardation value (Re550) measured at a wavelength of 550 nm is from 125 to 1
The touch panel according to claim 1, wherein the touch panel has a retardation value (Re590) measured at a wavelength of 590 nm of 130 to 152 nm, and satisfies the relationship of Re590-Re550 ≧ 2 nm. 3. The touch panel according to claim 1, wherein the cellulose ester film is a cellulose acetate film having an acetylation degree of 55.0 to 61.5%. 4. The cellulose ester film according to claim 1,
4. The touch panel according to claim 1, wherein the touch panel is a film made of cellulose acetate having a 6-position substitution ratio of 30% or more and 40% or less. 5. 5. The cellulose ester film comprises a compound having at least two aromatic rings and having a molecular structure that does not hinder the conformation of the two aromatic rings.
5. The touch panel according to any one of Items 4 to 4. 6. The cellulose ester 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
The touch panel according to claim 1, wherein the touch panel satisfies a relationship of (−nz) / (nx−ny) ≦ 2. 7. A polarizing film is further laminated on the cellulose ester film side, and the angle between the slow axis in the plane of the cellulose ester film and the polarizing axis of the polarizing film is substantially 4 °.
The touch panel according to claim 1, wherein the touch panel is arranged so as to be 5 °. 8. The touch panel according to claim 1, wherein a transparent conductive film having a surface resistivity of 10 ⁴ Ω / □ or less is provided on at least one surface of the cellulose ester film. . 9. A reflection type liquid crystal display device comprising a polarizing film, a λ / 4 plate, a touch panel and a reflection type liquid crystal cell,
The λ / 4 plate has a retardation value (Re450) measured at a wavelength of 450 nm of 100 to 125 nm and a retardation value (Re450) measured at a wavelength of 590 nm.
590) is from 120 to 160 nm, and Re590−
A reflection type liquid crystal display device comprising one sheet of cellulose ester film satisfying a relationship of Re450 ≧ 2 nm. 10. The reflective liquid crystal display device according to claim 9, wherein a polarizing film, a λ / 4 plate, a touch panel, and a reflective liquid crystal cell are stacked in this order. 11. The reflective liquid crystal display device according to claim 9, wherein the touch panel and the reflective liquid crystal cell share a single substrate, and transparent electrode layers are provided on both surfaces of the shared substrate. 12. A guest-host type liquid crystal display device provided with a λ / 4 plate, a touch panel and a guest-host type liquid crystal cell, wherein the λ / 4 plate has a retardation value (Re450) of 100 to 450 measured at a wavelength of 450 nm. 125 nm
And a retardation value (Re590) measured at a wavelength of 590 nm is 120 to 160 nm, and R
A guest-host type liquid crystal display device comprising one sheet of cellulose ester film satisfying a relationship of e590-Re450 ≧ 2 nm. 13. A λ / 4 plate, a touch panel, and a guest-host type liquid crystal cell are stacked in this order.
2. The guest-host type liquid crystal display device according to item 1. 14. The guest-host type liquid crystal display device according to claim 12, wherein the touch panel and the guest-host type liquid crystal cell share one substrate, and transparent electrode layers are provided on both sides of the shared substrate. .