JP2001089764A - Optical anisotropic materail, optical compensatory film and liquid crystal display element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical compensatory film having excellent scratch resistance and to provide a liquid crystal display element which uses the optical compensatory film and has a wide angle of visibility by making the optical compensatory film inclide an optical anisotropic material. SOLUTION: This optical anisotropic material contains at least one kind of cylindrical compound having optical anisotropy. The optical anisotropic material preferably contains at least one kind of compound which has optical anisotropy and is expressed by the general formula (1) [R1 is an alkyl an aryl, an aromatic heterocyclic group, an alkenyl, an acyl, an alkylsulfonyl, an arylsulfonyl, an alkylsulfinyl, an arylsulfinyl or phosphono; R2, R3, R4, R5 and R6 are each H, a halogen atom or a substituent; L is an integer of 4 to 6; provided that the total number of all carbon atoms in the compound of the general formula (1) is 35 to 200].

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optically anisotropic material, an optical compensation film, and a liquid crystal display device.

[0002]

2. Description of the Related Art Conventionally, a liquid crystal display uses a liquid crystal material or a polarizing plate having anisotropy, so that even if a good display is obtained when viewed from the front, display performance is deteriorated when viewed from an oblique direction. A viewing angle compensator is required to improve performance, and the average refractive index distribution is large in the thickness direction of the cell and smaller in the in-plane direction. Therefore, as the compensator, a compensator capable of canceling out this anisotropy and having a so-called negative uniaxial structure having a smaller refractive index in the film thickness direction than in the in-plane direction is effective.

From such a viewpoint, as a compensating plate capable of simultaneously performing color compensation and viewing angle compensation, a refractive index in a thickness direction is smaller than an in-plane refractive index while having in-plane retardation. The use of a biaxially stretched film has been proposed.

However, since the optical axis (hereinafter, referred to as a director) of the liquid crystal in the cell changes continuously in the film thickness direction, optical rotatory dispersion occurs. Although angle compensation is performed, there is a problem that sufficient compensation cannot be achieved when viewed from another direction.

[0005] Further, since the biaxially stretched film has no change in the refractive index in the thickness direction, there is also a problem that the influence of optical rotation dispersion cannot be completely canceled by the biaxially stretched film. .

Therefore, in order to sufficiently compensate the viewing angle of the liquid crystal display, it is necessary to have an in-plane retardation and a condition that the refractive index in the thickness direction is smaller than the in-plane refractive index. It is considered that the requirement that the refractive index continuously changes in the direction must be satisfied.

It has been proposed to use an optically anisotropic element obtained by fixing the orientation of a liquid crystalline compound as an optical compensation sheet (film) satisfying these conditions. Since the liquid crystal compound has various alignment forms, by fixing the alignment form, an optically anisotropic element having optical performance that cannot be obtained with a stretched film having a birefringence is obtained.

In recent optical compensatory sheets, for example, JP-A-09-104656, JP-A-09-194429, and JP-A-09-194430 disclose a discotic liquid crystal compound as a liquid crystal compound instead of a rod-shaped liquid crystal compound. It has been proposed to use a discotic liquid crystal compound in a polymer, or to introduce a polymerizable group into the discotic liquid crystal compound and stably fix the alignment state by a polymerization reaction. Actually, this is effective in expanding the viewing angle of the liquid crystal display.

However, even the compounds exhibiting discotic liquid crystal properties have not yet been sufficiently improved in viewing angle characteristics, and the discotic liquid crystal compounds have problems such as high production costs, and are particularly excellent in scratch resistance. There has been a demand for an optically anisotropic material, an optical compensation film containing the material, and a liquid crystal display device having improved viewing angle characteristics using the same.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to provide an optically anisotropic material, an optical compensation film having excellent scratch resistance by containing the optically anisotropic material, and an optical compensation film using the optical compensation film. An object of the present invention is to provide a liquid crystal display device having a viewing angle.

[0011]

The object of the present invention has been attained by the following items 1 to 12.

1. An optically anisotropic material comprising at least one cylindrical compound having optical anisotropy.

2. An optical compensation film comprising at least one cylindrical compound having optical anisotropy.

3. 3. A liquid crystal display device comprising the optical compensation film according to the above item 2.

4. An optically anisotropic material characterized by comprising at least one compound represented by the following general formula (1) and having optical anisotropy.

[0016]

Embedded image

[0017] formula, R ₁ represents an alkyl group, an aryl group, an aromatic heterocyclic group, an alkenyl group, an acyl group, an alkylsulfonyl group, an arylsulfonyl group, an alkylsulfinyl group, an arylsulfinyl group or a phosphono group, R ₂ , R ₃ , R ₄ , R ₅ , and R ₆ each represent a hydrogen atom, a halogen atom or a substituent, and L represents an integer of 4 to 6. However, the total number of carbon atoms of the compound represented by the general formula (1) is from 35 to 200.

5. An optical compensation film comprising at least one compound represented by the general formula (1) and having optical anisotropy.

6. A liquid crystal display device comprising the optical compensation film according to the above item 5.

[7] FIG. An optically anisotropic material, characterized by containing at least one compound represented by the following general formula (2) and having optical anisotropy.

[0021]

Embedded image

The formula, R ₁₁ represents an alkyl group, an aryl group, an aromatic heterocyclic group, an alkenyl group, an acyl group, an alkylsulfonyl group, an arylsulfonyl group, an alkylsulfinyl group, an arylsulfinyl group or a phosphono group, R ₁₄ , R ₁₅ and R ₁₆ each represent a hydrogen atom, a halogen atom or a substituent, and L ₁ represents an integer of 4 to 6. However, the total number of all carbon atoms of the compound represented by the general formula (2) is from 35 to 200.

8. An optical compensation film comprising at least one compound represented by the general formula (2) and having optical anisotropy.

9. A liquid crystal display device comprising the optical compensation film described in 8 above.

10. Represented by the following general formula (3), and
Optically anisotropic material containing at least one compound having optical anisotropy

[0026]

Embedded image

In the formula, R ₂₃ , R ₂₆ and R ₂₇ represent an alkyl group, an aryl group, an aromatic heterocyclic group, an alkenyl group, an acyl group,
Represents an alkylsulfonyl group, an arylsulfonyl group, an alkylsulfinyl group, an arylsulfinyl group or a phosphono group, and represents R ₂₁ , R ₂₂ , R ₂₄ , R ₂₅ , R ₂₈ , R ₂₉ ,
R ₂₁₀ represents a hydrogen atom, a halogen atom or a substituent, and L ₂ represents an integer of 6 to 8. However, the total number of carbon atoms of the compound represented by the general formula (3) is 4
0 to 300.

11. Represented by the general formula (3), and
An optical compensation film comprising at least one compound having optical anisotropy.

12. A liquid crystal display device comprising the optical compensation film according to the above item 11.

Hereinafter, the present invention will be described in more detail.

The cylindrical compound having optical anisotropy according to the present invention (also referred to as clathrate compound) will be described.

The cylindrical compound having optical anisotropy according to the present invention is not particularly limited as long as the compound is cylindrical. In the present invention, the compound represented by the above general formula (1), (2) or (3) )) And a compound having optical anisotropy is preferably used.

The compounds represented by the general formulas (1), (2) and (3) each have a core having a calixarene, a thiacalixarene and a cyclodextrin skeleton, respectively. Compound). In general, these compounds are very inexpensive and easily available, and therefore have a higher cost advantage than optically anisotropic materials using conventional discotic liquid crystal materials. Further, a feature of the cylindrical compound according to the present invention is that the refractive index in an extremely small region in the liquid crystal layer has a negative uniaxial property.

Having the negative uniaxiality described above means that the refractive indices in a certain plane are equal (n ₀ ), the direction perpendicular to the plane is the director, and the refractive index in the director direction is when the n _e, and has a n _0> n _e.

As described above, the optically anisotropic material and the optically compensatory film of the present invention represent materials having different refractive indexes in one direction and another direction.
Alternatively, it is composed of a composition containing at least one compound, and in the present invention, the orientational order of these molecules is not particularly limited.

The cylindrical compound according to the present invention and each of the compounds represented by the general formulas (1) to (3) can be fixed without impairing the alignment form in the liquid crystal state. Those which do not cause a transition from to a crystal phase are preferred. When a film is formed, it is desirable that the film be kept in an oriented form under the conditions of use and can be handled like a solid. Furthermore, the state of immobilization in the present invention is the most typical and preferable mode in which the liquid crystal structure is frozen in an amorphous glass state, but is not limited thereto, and the optical compensation film of the present invention is not limited thereto. Under the use conditions, specifically, usually from 0 ° C. to 50
° C, under more severe conditions, in a temperature range of -30 ° C to 70 ° C, the film has no fluidity, and does not cause a change in the alignment form due to an external field or external force. It refers to a state that can be kept stable.

From the above, as the cylindrical compound according to the present invention and the compounds represented by the above general formulas (1) to (3), those having any of the following properties are preferably used.

(A) It has only a glass phase at a temperature lower than the liquid crystal state and has no crystal phase. When the temperature is lowered from the liquid crystal state, it is fixed in the glass state. It has a crystal phase in a lower temperature range than the liquid crystal state, and further has a glass phase in a lower temperature range than the crystal phase, and when the temperature is lowered from the liquid crystal state,
The crystal phase does not appear (when the crystal phase is supercooled or when it is monotropic in which crystallization occurs only when the temperature is raised), and when the temperature is lowered from the liquid crystal state, it is fixed in the glass state.

(B) It has a crystal phase in a lower temperature range than the liquid crystal state, but does not show a clear glass transition in the lower temperature range, and when the temperature is lowered from the liquid crystal state,
No crystal phase appears (when the crystal phase is supercooled or monotropic in which crystallization occurs only at elevated temperature).
In this case, at a temperature lower than the melting point (observed when heated to a high temperature again after fixing), it can be regarded as a practically solid material in which the fluidity of the molecule is extremely limited.

(C) In the temperature range lower than the liquid crystal state, neither a clear transition to a crystal nor a transition to a glass state is observed during the temperature raising and lowering steps. There is no fluidity within the operating temperature range of the film, and the orientation form does not change even when an external force such as shearing or an external field is applied.

Of the above, more preferred are the cases of either (a) or (b), and the most preferred is the use of those having the properties described in (a).
It should be noted that any of the cases (b) and (c) can be used without any practical problems, but it is necessary to carefully check that there is no possibility of disordered orientation under the conditions of use of the film.

Specifically, in a temperature range of usually 0 ° C. to 50 ° C., there is no particular problem as long as, for example, misalignment is forcibly added and the orientation form is not disturbed. When the orientation is disturbed due to misalignment or the like, the original optical performance tends to be lost, and if it is lost, it is difficult to return to the original orientation even if any processing is performed. It becomes a big problem in use.

The cylindrical compound according to the present invention and the compounds represented by the above general formulas (1) to (3) have any of the above-mentioned properties, and at the same time, have a good orientation without a uniform defect. Those that show domain unity are desirable. When the integration of the domains is poor, the resulting structure becomes a polydomain, an alignment defect occurs at the boundary between the domains, and light is scattered. In addition, the transmittance of the film is undesirably reduced.

The tubular compound according to the present invention and the specific structures represented by the general formulas (1) to (3) are constituted by a central portion having a tubular skeleton and a substituent around the central portion. .
As the substituent, a monofunctional compound is preferably used, but a compound obtained by partially linking compounds using a bifunctional compound and oligomerizing or polymerizing is also used as the material of the present invention. It can be preferably used.

The compounds represented by formulas (1) to (3) will be described below in detail.

The compound represented by the general formula (1) has a total number of carbon atoms of 35 to 200, and in the general formula (1), R ₁
Is an alkyl group, an aryl group, an aromatic heterocyclic group, an alkenyl group, an acyl group, an alkylsulfonyl group, an arylsulfonyl group, an alkylsulfinyl group, an arylsulfinyl group or a phosphono group. Among them, an alkyl group is preferably used. , An acyl group.

Examples of the alkyl group represented by R ₁ include a methyl group, an ethyl group, an isopropyl group, a hydroxyethyl group, a methoxymethyl group, a trifluoromethyl group,
and a t-butyl group.

The aryl group represented by R ₁ includes a phenyl group, a naphthyl group, a p-tolyl group, a p-chlorophenyl group and the like.

The heteroaromatic ring group represented by R ₁ includes
Furan ring, thiophene ring, pyrrole ring, pyrazole ring,
Imidazole ring, oxazole ring, thiazole ring, 1,
2,3-oxadiazole ring, 1,2,3-triazole ring, 1,2,4-triazole ring, 1,3,4-thiadiazole ring, pyridine ring, pyridazine ring, pyrimidine ring, pyrazine ring, s- Triazine ring, benzofuran ring,
Indole ring, benzothiophene ring, benzimidazole ring, benzothiazole ring, purine ring, quinoline ring, isoquinoline ring and the like are used.

The alkenyl group represented by R ₁ is 2
-Propenyl group, 1-propenyl group, 1-methyl-3-
Butenyl group and the like.

Examples of the acyl group represented by R ₁ include an acetyl group and a benzoyl group.

Examples of the alkylsulfonyl group represented by R ₁ include a methylsulfonyl group and an ethylsulfonyl group.

Examples of the arylsulfonyl group represented by R ₁ include a benzenesulfonyl group and a p-toluenesulfonyl group.

Examples of the alkylsulfinyl group represented by R ₁ include a methylsulfinyl group and an ethylsulfinyl group.

The arylsulfinyl group represented by R ₁ includes a benzenesulfinyl group and the like.

In the general formula (1), R ₂ , R ₃ , R ₄ ,
R ₅ and R ₆ each represent a hydrogen atom, a halogen atom, or a substituent, and specific substituents include an alkyl group (for example, a methyl group, an ethyl group, an isopropyl group, a hydroxyethyl group, a methoxymethyl group, Trifluoromethyl group,
t-butyl group, etc.), cycloalkyl group (eg, cyclopentyl group, cyclohexyl group, etc.), aralkyl group (eg, benzyl group, 2-phenethyl group, etc.), aryl group (eg, phenyl group, naphthyl group, p-tolyl) Group, p
-Chlorophenyl group, etc.), alkoxyl group (eg, methoxy group, ethoxy group, isopropoxy group, n-butoxy group, etc.), aryloxy group (eg, phenoxy group, etc.), cyano group, acylamino group (eg, acetylamino group) , Propionylamino group, etc.), alkylthio group (eg, methylthio group, ethylthio group, n-butylthio group, etc.), arylthio group (eg, phenylthio group, etc.), sulfonylamino group (eg, methanesulfonylamino group, benzenesulfonylamino group) Ureido group (eg, 3-methylureido group, 3,3-dimethylureido group, 1,3-dimethylureido group, etc.), sulfamoylamino group (dimethylsulfamoylamino group, etc.), carbamoyl group ( For example, a methylcarbamoyl group, an ethylcarbamoyl group, Methylcarbamoyl group, etc.), sulfamoyl group (eg, ethylsulfamoyl group, dimethylsulfamoyl group, etc.), alkoxycarbonyl group (eg, methoxycarbonyl group, ethoxycarbonyl group, etc.), aryloxycarbonyl group (eg, phenoxycarbonyl group) Group), alkylsulfonyl group or arylsulfonyl group (eg, methanesulfonyl group, butanesulfonyl group, phenylsulfonyl group, etc.), acyl group (eg, acetyl group, propanoyl group, butyroyl group, etc.), amino group (methylamino group) , An ethylamino group, a dimethylamino group, etc.), a hydroxyl group, a nitro group, an imide group (eg, a phthalimide group), a heterocyclic group (eg, a pyridyl group, a benzimidazolyl group, a benzothiazolyl group, a benzoxazolyl group, etc.) But But are lower, among others, particularly preferred are alkyl groups. L in the general formula (1) represents an integer of 4 to 6.

R ₁₁ in formula (2) has the same meaning as R ₁ in formula (1), and R ₁₄ , R ₁₅ ,
R ₁₆ has the same meaning as R ₂ , R ₃ , R ₄ , R ₅ and R ₆ in the general formula (1). L ₁ in the general formula (2) represents an integer of 4 to 6.

R ₂₃ , R ₂₆ and R ₂₇ in the general formula (3) have the same meaning as R ₁ in the general formula (1), but may be the same or different. R ₂₁ , R ₂₂ ,
R ₂₄ , R ₂₅ , R ₂₈ , R ₂₉ , and R ₂₁₀ have the same meanings as R ₂ , R ₃ , R ₄ , R ₅ , and R _{6 in the} general formula (1). It preferably has an aryl group in the moiety, and more preferably contains a group in which an alkyl group and an aryl group such as the following C to K and O to W are connected by a joint group in the molecule. Further, it is also a preferable example that the cyclodextrin includes an aromatic compound,
Specific compounds to be included include naphthalene, anthracene, quinoline and the like. L ₂ in the general formula (3) represents an integer of 6 to 8.

Hereinafter, specific examples of the compounds represented by formulas (1) to (3) are shown below, but the present invention is not limited thereto.

[0060]

Embedded image

[0061]

Embedded image

[0062]

Embedded image

[0063]

Embedded image

[0064]

Embedded image

[0065]

Embedded image

[0066]

Embedded image

However, C _n H _{2n + 1} is a linear or branched alkyl group, and n is an integer of 1 to 18, more preferably 3 to
It is an integer of 14.

[0068]

Embedded image

However, C _m H _2m is a linear or branched alkylene chain, and m is an integer of 2 to 16, more preferably 4 to
It is an integer of 12.

In the following, examples of the synthesis of each compound represented by the general formula (1), (2) or (3) according to the present invention are shown below.

Synthesis Example 1 << Synthesis of Compound (1) -1 >> Calixarene 50 m
mol, the following compound 4 and 200 mmol were dissolved in 1 liter of dry pyridine,
The solution was stirred for hours. Next, the reaction solution was poured into 10 liters of water, and the precipitate was separated by filtration, washed with 0.1N hydrochloric acid, then washed with pure water, and dried to obtain Compound (I) -1. Structure is MS (mass spectrometry), NMR
(Nuclear magnetic resonance) and the like.

[0072]

Embedded image

Synthesis Example 2 << Synthesis of Compound (2) -1 >> Thiacalixarene 5
0 mmol, the following compound 5 and 200 mmol were dissolved in 1 liter of dry pyridine, and 90 ° C. under a nitrogen atmosphere.
For 5 hours. Next, the reaction solution was poured into 10 liters of water, and the precipitate was separated by filtration, washed with 0.1N hydrochloric acid, then with pure water, and dried to obtain compound (2) -1. Structure is MS (mass spectrometry), NMR
(Nuclear magnetic resonance) and the like.

[0074]

Embedded image

Synthesis Example 3 << Synthesis of Compound (3) -1 >> α-cyclodextrin 5
0 mmol, the following compound 6 and 300 mmol are dissolved in 1 liter of dry pyridine, and 90 ° C. under a nitrogen atmosphere.
For 5 hours. Next, the reaction solution was poured into 10 liters of water, and the precipitate was separated by filtration, washed with 0.1N hydrochloric acid, then washed with pure water, and dried to obtain compound (3) -1. Structure is MS (mass spectrometry), NMR
(Nuclear magnetic resonance) and the like.

[0076]

Embedded image

The compound represented by the above general formula (1), (2) or (3) according to the present invention can be prepared according to Synthesis Example 1 described above,
2 or 3 can be synthesized with reference to each.

The optical compensation film of the present invention is a film for compensating for the viewing angle, and it is preferable that the director is different between the upper surface and the lower surface of the film, and it is more preferable that the hybrid orientation gradually changes in the film thickness direction. The optical axis does not exist and the uniaxiality is lost.

In order to perform sufficient viewing angle compensation,
It is necessary to cause optical rotation dispersion for light traveling obliquely. Therefore, the refractive index structure must change in the film thickness direction. Therefore, the hybrid alignment is most suitable for performing a wide range of viewing angle compensation on a liquid crystal display.

In the present invention, the angle range in the film thickness direction of the hybrid oriented film is determined by the absolute value of the minimum angle between the director of the film and the film plane, that is, the normal to the film director and the normal to the film plane. When an angle that is not the obtuse angle side (an angle in the range of 0 to 90 degrees) is a degree, the angle obtained by [90 degrees-a degree] is usually one of the upper and lower surfaces of the film. It forms an angle of 60 to 90 degrees, and is usually 0 to 50 degrees on the surface opposite to the surface. More preferably, the absolute value of one angle is 80 degrees to 90 degrees, and the absolute value of the other angle is 0 degrees to 30 degrees.

To obtain a compensation film in which the hybrid orientation is fixed uniformly using the tubular compound according to the present invention,
It is preferable to carry out the substrate and each step described below.

First, the substrate will be described. In order to obtain the hybrid orientation used in the present invention, it is desirable to sandwich the upper and lower portions of the liquid crystalline material at different interfaces, and when sandwiching the upper and lower portions at the same interface, the alignment at the upper and lower interfaces of the liquid crystalline layer is the same. This makes it difficult to obtain the hybrid alignment used in the present invention.

As a specific mode, one substrate and an air interface are used, and the lower interface of the liquid crystal layer is in contact with the substrate, and the upper interface is in contact with air. Although the substrate having different interfaces at the top and bottom can be used, it is preferable to use one substrate and the air interface from the viewpoint of the manufacturing process.

The substrate that can be used in the present invention is desirably an anisotropic alignment substrate so that the tilt direction of the liquid crystal (projection of the director onto the alignment substrate) can be defined. The alignment substrate has a function of defining the alignment direction of the compound of the optically anisotropic layer. The alignment substrate is formed by rubbing an organic compound (preferably a polymer), obliquely depositing an inorganic compound, forming a layer having microgrooves, or an organic compound (eg, ω-trichosanoic acid) by the Langmuir-Blodgett method (LB film). , Dioctadecylmethylammonium chloride, methyl stearylate). Further, an alignment substrate that has an alignment function by applying an electric field, applying a magnetic field, or irradiating light is also known.

The oriented substrate used in the present invention is preferably formed by rubbing a polymer. Specific examples of the oriented substrate include polyimide, polyamideimide, polyamide, polyetherimide, polyetheretherketone, and polyetheretherketone. Ether ketone, polyketone sulfide, polyether sulfone, polysulfone, polyphenylene sulfide, polyphenylene oxide, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyacetal, polycarbonate, polyarylate, acrylic resin, polyvinyl alcohol, polypropylene, cellulose plastics, epoxy Plastic film substrate such as resin and phenolic resin and uniaxially stretched film substrate, slit-shaped grooves on the surface Attached aluminum, iron, metal substrates such as copper, alkali glass etched surface in a slit form, borosilicate glass, a glass substrate such as flint glass, and the like.

In the present invention, the above-mentioned various substrates obtained by subjecting the above substrate to a surface treatment such as a hydrophilic treatment or a hydrophobic treatment may be used. In the above various alignment substrates, the substrate suitable for forming the cylindrical compound according to the present invention in a hybrid alignment includes a substrate having a rubbing polyimide film, a rubbing polyimide substrate, a rubbing polyetheretherketone substrate, and a rubbing polyetheretherketone. Substrates, rubbing polyethersulfone substrates, rubbing polyphenylene sulfide substrates, rubbing polyethylene terephthalate substrates, rubbing polyethylene naphthalate substrates, rubbing polyarylate substrates, and cellulose-based plastic substrates can be given.

The optical compensation film of the present invention can be obtained by applying the cylindrical compound according to the present invention onto such an oriented substrate, followed by a uniform orientation step and a fixing step. Coating on the substrate can be performed using a solution in which the material is dissolved in various solvents or a material in a molten state,
From the viewpoint of the process, solution coating is preferably performed using a solution in which the tubular compound according to the present invention is dissolved in a solvent. Hereinafter, the solution application will be described.

A solution having a predetermined concentration is prepared by dissolving the tubular compound according to the present invention in a solvent. The solvent at this time depends on the type of the material, but is usually a halogenated hydrocarbon such as chloroform, dichloromethane, carbon tetrachloride, dichloroethane, tetrachloroethane, tritrichloroethylene, tetrachloroethylene, chlorobenzene, orthodichlorobenzene, phenol, or parachlorobenzene. Phenols such as phenol, aromatic hydrocarbons such as benzene, toluene, xylene, methoxybenzene and 1,2-dimethoxybenzene, acetone, ethyl acetate, t-butyl alcohol, glycerin, ethylene glycol, triethylene glycol, ethylene glycol Monomethyl ether, diethylene glycol dimethyl ether, ethyl cellosolve, butyl cellosolve, 2-pyrrolidone, N-methyl-
For example, 2-pyrrolidone, pyridine, triethylamine, dimethylformamide, dimethylacetamide, acetonitrile, butyronitrile, carbon disulfide and the like, and a mixed solvent thereof are used.

The concentration of the solution depends on the solubility of the material and the final thickness of the target optical compensation film, but is usually used in the range of 1 to 60% by weight, preferably 3 to 60% by weight.
It is in the range of 40% by weight. These solutions are then applied on the alignment substrate described above.

As a coating method, a spin coating method, a roll coating method, a printing method, an immersion pulling method, a curtain coating method (die coating method) and the like can be adopted. After application,
The solvent is removed, and a layer having a uniform thickness is first formed on the substrate. The conditions for removing the solvent are not particularly limited, and it is sufficient that the solvent can be substantially removed and the layer of the material does not flow or does not even flow down. Usually, the solvent is removed by air drying at room temperature, drying on a hot plate, drying in a drying furnace, or blowing hot or hot air.

The purpose of this coating / drying step is to first form a layer of the tubular compound according to the present invention uniformly on the substrate, and the material layer has not yet formed a hybrid orientation. Therefore, in order to perform hybrid alignment, it is preferable in the present invention to perform the following heat treatment.

The heat treatment is preferably performed at a temperature higher than the liquid crystal transition point of the cylindrical compound according to the present invention. That is, the alignment is performed in the liquid crystal state of the material, or the material is once brought into an isotropic liquid state higher than the temperature range in which the material exhibits a liquid crystal phase, and then the temperature is lowered to the temperature range in which the material exhibits a liquid crystal phase. Usually, the temperature of the heat treatment is in the range of 50 ° C. to 300 ° C., and particularly preferably in the range of 100 ° C. to 250 ° C.

Although the time required for the liquid crystal to be sufficiently oriented depends on the cylindrical compound according to the present invention, it cannot be said unconditionally, but it is usually performed in the range of 5 seconds to 2 hours.
Preferably in the range of 10 seconds to 40 minutes, particularly preferably 20 seconds
The range is from seconds to 20 minutes. If the time is shorter than 5 seconds, the temperature of the material layer may not rise to a predetermined temperature and the orientation may be insufficient. If the time is longer than 2 hours, productivity may be reduced, which is not preferable. Through the above steps, first, a hybrid alignment can be formed in a liquid crystal state.

In the present invention, in the heat treatment step, a magnetic field or an electric field may be used in order to orient the cylindrical compound according to the present invention. The hybrid alignment in the liquid crystal state thus obtained is then cooled or polymerized by light or heat to fix the alignment without impairing the alignment form, thereby obtaining the optical compensation film of the present invention.

In general, when a crystal phase appears during the cooling process, the orientation in the liquid crystal state is destroyed by crystallization, but the tubular compound according to the present invention has no crystal phase or has a potential Although it has the property that the crystal phase does not appear when cooled even if it has a crystal phase, or a clear crystal transition point and a liquid crystal transition point are not confirmed, but there is no fluidity within the operating temperature range of the film, and Since a material having such a property that the orientation form does not change even when an external field or an external force is applied is used, the orientation form is not broken by crystallization.

In the present invention, the angle in the film thickness direction of the hybrid oriented film is such that the absolute value of the angle between the director of the film and the film plane is 60 degrees to 90 degrees on one of the upper and lower surfaces of the film. 0 degree to 50 degrees within the range of the degree and on the opposite side of the plane.
Within the range of degrees. The angles can be adjusted to desired angles by appropriately selecting the compound to be used, the alignment substrate, and the like. Even after the film is once formed, the angle can be adjusted to a desired angle by using a method such as uniformly shaving the film surface or immersing the film surface in a solvent to uniformly dissolve the film surface. The solvent used at this time is appropriately selected depending on the compound used and the type of the alignment substrate.

When the optical compensation film of the present invention obtained by the above steps is actually arranged in a liquid crystal cell, the above-mentioned orientation substrate is peeled off from the film as a mode of use of the film, and the compensation film is used alone. It can be used as it is formed on a substrate.

When the optical compensation film of the present invention is used as a single film, a method of mechanically peeling the oriented substrate at the interface with the optical compensation film using a roll or the like,
A method of mechanically peeling after immersion in a poor solvent for all structural materials, a method of peeling by applying ultrasonic waves in a poor solvent, and giving a temperature change using a difference in thermal expansion coefficient between an oriented substrate and the film Peeling method, the alignment substrate itself,
Alternatively, a method of dissolving and removing an alignment film on an alignment substrate can be exemplified.

Since the releasability varies depending on the adhesion between the cylindrical compound according to the present invention and the alignment substrate, the method most suitable for the system is applied.

Next, when the optical compensation film is used in a state formed on an alignment substrate, it may be used when the alignment substrate is transparent and optically isotropic, or when the alignment substrate is a member necessary for a liquid crystal display device. Can be used as it is as a target liquid crystal display element. Further, obtained by fixing the cylindrical compound according to the present invention on the alignment substrate, the optical compensation film of the present invention is peeled from the substrate,
It can be used by being transferred to another substrate more suitable for optical use.

For example, if the alignment substrate to be used is necessary for obtaining a hybrid alignment mode, but the substrate has an undesired effect on the liquid crystal display element, the substrate is fixed in alignment. It can be used after being removed from the optically-compensatory film after the formation. Specifically, the following method can be adopted. A substrate suitable for a liquid crystal display element to be incorporated in a target liquid crystal display device and a compensation film on an alignment substrate are attached using an adhesive or an adhesive. Next, the liquid crystal display element can be manufactured by peeling off at the interface between the alignment substrate and the compensation film of the present invention, and transferring the compensation film to a substrate side suitable for a liquid crystal display element.

The substrate suitable for the liquid crystal display element used for the transfer is not particularly limited as long as it has an appropriate flatness, but glass or a transparent plastic film having optical isotropy is preferred. Examples of such a plastic film include polymethacrylate, polystyrene, polycarbonate, polyether sulfone, polyphenylene sulfide, polyarylate, amorphous polyolefin, triacetyl cellulose, and epoxy resin. Among them, polymethyl methacrylate, polycarbonate, polyarylate, triacetyl cellulose, polyether sulfone and the like are preferably used. Further, even if it is optically anisotropic, it can be used as it is if it is necessary for a liquid crystal display element. Examples of such a film include a retardation film and a polarizing film obtained by stretching a plastic film such as polycarbonate or polystyrene.

Further, a liquid crystal display cell itself can be cited as an example of the second substrate. The liquid crystal display cell uses two upper and lower glass substrates with electrodes, and if the optical compensation film of the present invention is transferred onto either one of the upper or lower glass or both surfaces of glass, the incorporation of the present optical compensation film has already been achieved. It will be. It is of course possible to manufacture the optical compensation film of the present invention using the glass substrate itself forming the display cell as an alignment substrate. The adhesive or pressure-sensitive adhesive for adhering the second substrate used for the transfer and the optically anisotropic material of the present invention is not particularly limited as long as it is of optical grade, but may be acrylic, epoxy, ethylene-vinegar. Bi-copolymers, rubbers, urethanes, and mixtures thereof can be used.

The transfer of the optical compensation film of the present invention to a substrate suitable for a liquid crystal display device can be performed by peeling the oriented substrate at the interface with the film after bonding. As the method of peeling, the method described above can be exemplified.
The optical compensation film of the present invention may be provided with a protective layer such as a transparent plastic film for protecting the surface.

The thus obtained optically compensatory film of the present invention is incorporated into a liquid crystal display device in an arrangement as described below to exhibit an optically compensating effect, ie, a viewing angle compensation, on a liquid crystal display. it can. The optical compensatory film is usually used as one or more sheets, but preferably one or two sheets, especially two sheets, can exhibit a suitable optical compensation effect.

For the purpose of compensating the viewing angle, it is more preferable that the absolute value of the product of the birefringence of the liquid crystal and the film thickness is substantially equal between the liquid crystal cell and the optically anisotropic material. The birefringence here is the anisotropy of the refractive index inherent in the liquid crystal, and the refraction in the optical axis direction obtained when the director of the liquid crystal is uniaxially oriented so as to face one direction. It is the difference between the index and the refractive index in the direction perpendicular to it. The product of such birefringence and film thickness is usually 100 nm to 3000 nm, preferably 200 nm, for the liquid crystal cell and the optical compensation film.
２０００2000 nm, more preferably 300 nm〜150
0 nm. When a plurality of optical compensation films are used, the value obtained by summing the absolute values of the products of the birefringence and the film thickness of each optical compensation film is preferably within the above range. However, the value obtained by multiplying the birefringence and the film thickness does not necessarily need to be completely the same between the liquid crystal cell and the optical compensation film. As compared with the case where no film is incorporated, a remarkable viewing angle compensation effect can be obtained.

The optical compensation film of the present invention is incorporated into a liquid crystal display device under the above-described arrangement conditions. Liquid crystal display elements other than the optical compensation film incorporated in the device, such as a polarizing plate and a driving liquid crystal cell, are not particularly limited, but the arrangement conditions, materials, and the like of each element will be described below.

A liquid crystal cell is obtained by sandwiching a nematic liquid crystal material between two electrode substrates that have been subjected to alignment treatment. As the electrode substrate, a glass substrate or a plastic substrate having an ITO conductive film, a transistor thin film electrode, a diode thin film electrode, or the like can be used. The alignment film is disposed on the electrode substrate, and a rubbing polyimide film, a rubbing polyvinyl alcohol film, or the like is usually used. As the alignment film, an obliquely deposited silicon oxide film or the like can be preferably used.

The optical compensation film of the present invention, when used as one or a plurality of sheets, exerts a remarkable effect in improving the viewing angle of a liquid crystal display. In addition, conventional optical films, for example, an optical film having a negative uniaxial refractive index structure,
It is also possible to use in combination with an optical film having a positive uniaxial refractive index structure or an optical film having a biaxial refractive index structure. Further, the polarizing plate can be used in combination with a polarizing plate having improved viewing angle dependency. However, the optical compensatory film of the present invention plays a decisive role in compensation, and excellent compensation such as the optical compensatory film of the present invention is obtained no matter how the conventional optical film alone is used in any combination. It is impossible to achieve the effect.

The measurement of the optical anisotropy of the optically anisotropic material and / or the optically compensatory film of the present invention is specifically performed by ellipsometry using a polarizing microscope. As the measurement results, the optical axis inclination angle β and the retardation (Δn × d) are obtained.
β is preferably 5 to 50 degrees, more preferably,
It is 10 to 40 degrees, and the retardation is preferably 100 to 400 nm.

As described above, the liquid crystal display device incorporating the optical compensation film of the present invention can obtain a wide viewing angle which has not been obtained conventionally.

In the conventional liquid crystal cell, the setting range of the parameters of the liquid crystal cell is limited in order to obtain a viewing angle as wide as possible. However, the optical compensatory film of the present invention can easily control the orientation mode, and can almost completely compensate for the orientation mode of any liquid crystal cell. Therefore, the degree of freedom in setting the parameters of the liquid crystal cell is widened, and the optical compensation film of the present invention is highly valuable from the viewpoint of industrial production of the liquid crystal cell.

[0113]

The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples.

Example 1 << Preparation of Optical Compensatory Film 1 of the Present Invention >> Polyethersulfone 100 μm thick film (FS-1300 manufactured by Sumitomo Bakelite Co., Ltd.), size (100 μm × 10
0 μm) as a base, a 0.1 μm gelatin undercoat layer is provided, and a polyamic acid SE-72 is used as an alignment film thereon.
10 (manufactured by Nissan Chemical Industries, Ltd.) and baked at 180 ° C. to form a polyimide film.

The polyimide film was rubbed with a rubbing machine to give an alignment film. Next, the compound (1) -1 obtained in Synthesis Example 1 described above was dissolved in MEK (methyl ethyl ketone), and a 10% by weight solution was applied using a spin coater under a rotation condition of 1000 rpm to form a non-oriented layer. Thus, a film-like material (1) was obtained.

The obtained film-form (1) was heated to a predetermined temperature, oriented, rapidly cooled, and the optical axis inclination angles β and Δnxd were measured by ellipsometry.

For the measurement, an ellipsometer AEP-10 was used.
By setting 0 (manufactured by Shimadzu Corporation) in the transmission mode, the angle dependence of the retardation was determined, and from these values, the optimum refractive index in the three axial directions and the direction of the optical axis were calculated.

Compound (1) -1 forms a liquid crystal phase at about 142 to 155 ° C. according to a polarizing microscope. Therefore,
The film-like material (1) was brought into contact with the metal roller heated to a surface temperature of 160 ° C. from the support side for 50 seconds.
The sheet was brought into contact with a metal roller adjusted to a surface temperature of 20 ° C. for 10 seconds to obtain a sheet-shaped optical compensation film 1 of the present invention.

When this sheet was observed with a polarizing microscope, it was observed that the sheet had a monodomain orientation state. Further, by the ellipsometry measurement, the optical axis inclination angle β was 15 degrees, and the retardation (Δn × d)
Was 126 nm.

<< Preparation of Optical Compensation Film 2 of the Present Invention >> Compound (1) used for preparing optical compensation film 1 of the present invention
Similarly, except that -1 was replaced with the compound (2) -1, a film-like substance (2) was obtained.

Compound (2) -1 forms a liquid crystal phase at about 114 to 131 ° C. according to observation with a polarizing microscope. Then, the film-shaped material (2) is brought into contact with the metal roller heated to the surface temperature of 120 ° C. from the support side for 30 seconds, and immediately thereafter, is brought into contact with the metal roller adjusted to the surface temperature of 20 ° C. for 10 seconds, thereby forming a sheet-like material. An optical compensation film 2 of the present invention was obtained.

When the above sheet was observed using a polarizing microscope, it was observed that the sheet had a monodomain orientation state. Furthermore, by ellipsometry measurement,
The optical axis tilt angle β is 25 degrees, and the retardation (Δn ×
d) was 190 nm.

<< Preparation of Optical Compensation Film 3 of the Present Invention >> Compound (1) used for preparing optical compensation film 1 of the present invention
In the same manner as above, except that -1 was replaced with compound (3) -1, a film-like product (3) was obtained.

Compound (3) -1 forms a liquid crystal phase at about 225-234 ° C. according to observation with a polarizing microscope. Then, the film-shaped material (3) is brought into contact with the metal roller heated to the surface temperature of 240 ° C. from the support side for 30 seconds, and immediately thereafter, is brought into contact with the metal roller adjusted to the surface temperature of 20 ° C. for 10 seconds, thereby forming a sheet-like material. An optical compensation film 3 of the present invention was obtained.

When the above sheet was observed using a polarizing microscope, it was observed that the sheet had a monodomain orientation state. Furthermore, by ellipsometry measurement,
The optical axis tilt angle β is 20 degrees, and the retardation (Δn ×
d) was 135 nm.

<< Preparation of Comparative Optical Compensation Film 4 >> Compound (1)-used in preparation of optical compensation film 1 of the present invention
A film-like product (x) was obtained in the same manner except that 1 was changed to the following compound (x).

[0127]

Embedded image

The comparative compound (x) forms a liquid crystal phase at about 143 to 158 ° C. according to observation with a polarizing microscope. Then, the film-shaped material (x) is brought into contact with the metal roller heated to the surface temperature of 150 ° C. from the support side for 30 seconds, and immediately thereafter, is brought into contact with the metal roller adjusted to the surface temperature of 20 ° C. for 10 seconds, thereby forming a sheet-like material. A comparative optical compensation film 4 was obtained.

When the above sheet was observed using a polarizing microscope, it was observed that the sheet had a monodomain orientation state. Furthermore, by ellipsometry measurement,
The optical axis tilt angle β is 30 degrees, and the retardation (Δn ×
d) was 127 nm.

<< Preparation of Comparative Optical Compensation Film 5 >> Compound (1)-used in preparation of optical compensation film 1 of the present invention
In the same manner, except that 1 was changed to the following compound (y),
An attempt was made to produce an optical compensation film, but the comparative compound (y)
Was insoluble in MEK, and no optical compensation film was obtained.

[0131]

Embedded image

<< Preparation of Comparative Optical Compensation Film 6 >> Compound (1)-used in preparation of optical compensation film 1 of the present invention.
In the same manner, except that 1 was replaced with the following compound (z),
A film-like material (z) was prepared. When the ellipsometry was measured, the retardation (Δnxd) was 0.
And no optical anisotropy appeared.

[0133]

Embedded image

With respect to the optical compensation films 1, 2 and 3 of the present invention obtained above and the compensation film 4 for comparison, the scratch resistance was evaluated by the following method.

<< Evaluation of scratch resistance of optical compensation film >> Surface measurement device HEIDON equipped with diamond scratching needle
Using -22 (manufactured by Shinto Kagaku), the optical compensation films 1, 2, and 3 of the present invention and the comparative optical compensation film 4 were continuously weighted while moving each sample at a moving speed of 55 mm / min. Was changed from 0 to 50 g, and the weight at which a change in the friction coefficient was observed (the weight at which the diamond needle bites into the optical compensation film sample) was measured, and the scratch resistance was evaluated. When the weight is 35 g or more, the film has good scratch resistance. The temperature during the measurement was adjusted to 30 ° C. Table 1 shows the obtained results.

[0136]

[Table 1]

From Table 1, it can be seen that Samples 1, 2 and 3 of the present invention, which are optical compensation films having a cylindrical compound having optical anisotropy, have superior scratch resistance as compared with Comparative Optical Compensation Film 4. It is clear to show.

Example 2 << Preparation of Liquid Crystal Display Element of the Present Invention >> 127 μm thick film of TAC (cellulose triacetate) (100 mm ×
100 μm) as a substrate (support), 0.1 μm
Was coated with a modified poval as an alignment film, and this film was rubbed with a rubbing machine to give an alignment film. Compound (2) -1 was dissolved in MEK (methyl ethyl ketone), and a 10 wt% solution was applied at 1000 rpm by a spin coater to prepare a film.

Next, the above-mentioned film was brought into contact with the metal roller heated to a surface temperature of 120 ° C. from the substrate (support) side for 30 seconds. By contact, an optical compensation film of the present invention was obtained. Next, a product of the difference between the refractive index of the extraordinary light and the normal light of the liquid crystal and the gap size of the liquid crystal cell is 440 nm, and the twist angle is 90 degrees.
Two optical compensation films were arranged so as to sandwich the cell. At that time, the optically anisotropic layer of the optical compensation sheet and the glass substrate of the liquid crystal cell are arranged so as to face each other, and the rubbing direction of the alignment film of the liquid crystal cell and the rubbing direction of the alignment film of the optical compensation sheet are antiparallel. It was arranged to become.

The polarizing elements were arranged in crossed Nicols on both sides of these to obtain the liquid crystal display element 1 of the present invention. Further, a comparative liquid crystal display element 2 using only TN liquid crystal was produced in the same manner as in the production of the liquid crystal display element 1 of the present invention except that the optical compensation film of the present invention was not used at all.

With respect to the two kinds of obtained samples, the angle dependency of the contrast in a 30 Hz rectangular wave of 0-5 V was measured using an instrument (EZ-Contrast 160D, manufactured by ELDIM). At the time of measurement, the position of the contrast 10 was defined as the viewing angle, and the up, down, left, and right viewing angles were obtained. Also, the contrast ratio when viewed from the front was measured. Table 2 shows the obtained results.

[0142]

[Table 2]

From Table 2, it can be seen that, as compared with the comparative liquid crystal display element,
It is clear that the liquid crystal display device of the present invention loaded with the optical compensation film of the present invention achieves a remarkable improvement in viewing angle characteristics.

[0144]

According to the present invention, an optically anisotropic material, an optical compensation film having excellent scratch resistance by containing the optically anisotropic material, and a liquid crystal display device having a wide viewing angle using the optical compensation film. Could be provided.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) G02F 1/13363 G02F 1/13363 // C08J 5/18 C08J 5/18 F term (reference) 2H049 BA06 BA42 BB54 BC02 BC14 2H091 FA11X FA11Z FC01 GA03 GA06 HA07 KA02 LA17 LA19 4F006 AA19 AA22 AA32 AA35 AA36 AA38 AA39 AA40 AB62 AB64 BA06 CA05 DA04 EA06 4F071 AA20 AA29 AA32. CH01 CH02 CH03 CH04 DH01 DH02 DH03 DH04 DK01 DL01

Claims (12)

[Claims] 1. An optically anisotropic material comprising at least one cylindrical compound having optical anisotropy. 2. An optical compensation film comprising at least one cylindrical compound having optical anisotropy. 3. A liquid crystal display device comprising the optical compensation film according to claim 2. 4. An optically anisotropic material characterized by comprising at least one compound represented by the following general formula (1) and having optical anisotropy. Embedded image Wherein R ₁ is an alkyl group, an aryl group, an aromatic heterocyclic group, an alkenyl group, an acyl group, an alkylsulfonyl group,
An arylsulfonyl group, an alkylsulfinyl group, an arylsulfinyl group or a phosphono group, R _2,
R ₃ , R ₄ , R ₅ and R ₆ each represent a hydrogen atom, a halogen atom or a substituent, and L represents an integer of 4 to 6. However, the total number of carbon atoms of the compound represented by the general formula (1) is from 35 to 200. ] 5. An optical compensation film comprising at least one compound represented by the general formula (1) and having optical anisotropy. 6. A liquid crystal display device comprising the optical compensation film according to claim 5. 7. An optically anisotropic material characterized by comprising at least one compound represented by the following general formula (2) and having optical anisotropy. Embedded image Wherein R ₁₁ is an alkyl group, an aryl group, an aromatic heterocyclic group, an alkenyl group, an acyl group, an alkylsulfonyl group,
An arylsulfonyl group, an alkylsulfinyl group, an arylsulfinyl group or a phosphono group, R _14, R
₁₅ and R ₁₆ each represent a hydrogen atom, a halogen atom or a substituent, and L ₁ represents an integer of 4 to 6. However, the sum of the total number of carbon atoms of the compound represented by the general formula (2) is
35 to 200. ] 8. An optical compensation film comprising at least one compound represented by the general formula (2) and having optical anisotropy. 9. A liquid crystal display device comprising the optical compensation film according to claim 8. 10. An optically anisotropic material represented by the following general formula (3) and containing at least one compound having optical anisotropy. [Wherein, R ₂₃ , R ₂₆ and R ₂₇ represent an alkyl group, an aryl group,
It represents an aromatic heterocyclic group, an alkenyl group, an acyl group, an alkylsulfonyl group, an arylsulfonyl group, an alkylsulfinyl group, an arylsulfinyl group or a phosphono _{group, R 21, R 22, R} 24, R 25, R 28, R 29 , R ₂₁₀ is
Each represents a hydrogen atom, a halogen atom or a substituent,
L ₂ represents an integer of 6-8. However, the sum of the total number of carbon atoms of the compound represented by the general formula (3) is 40 to 300.
It is. ] 11. An optical compensation film comprising at least one compound represented by the general formula (3) and having optical anisotropy. 12. A liquid crystal display device comprising the optical compensation film according to claim 11.