JP2641086B2 - Manufacturing method of optical compensation sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an optical compensatory sheet which can be used in a liquid crystal display device to improve the display contrast and the viewing angle characteristics of display colors.

[0002]

2. Description of the Related Art CRTs, which are the mainstream display devices for OA equipment such as Japanese word processors and desktop personal computers,
The liquid crystal display device has been converted to a liquid crystal display device having great advantages such as thin and light weight and low power consumption. Many of the liquid crystal display elements (hereinafter referred to as LCDs) that are currently widely used use twisted nematic liquid crystals. Display methods using such a liquid crystal can be roughly classified into two modes, a birefringence mode and an optical rotation mode.

An LCD using a birefringence mode has a liquid crystal molecule arrangement in which the twist angle is twisted by 90 ° or more and has a steep electro-optical characteristic. Therefore, a simple matrix without an active element (thin film transistor or diode) is used. A large-capacity display can be obtained by the time-sharing behavior in the shape of the electrode. But,
It has the disadvantage that the response speed is slow (several hundred milliseconds) and that gradation display is difficult.
LCD or MIM-LCD).

In the TFT-LCD and the MIM-LCD, an optical rotation mode display mode (TN type liquid crystal display element) in which the alignment state of liquid crystal molecules is twisted by 90 ° is used. This display method is the most influential method as compared with other types of LCDs, since it has a fast response speed (several tens of milliseconds), easily obtains a black-and-white display, and shows a high display contrast. However, since the twisted nematic liquid crystal is used, there is a problem in viewing angle characteristics that a display color and a display contrast change depending on a viewing direction due to a principle of a display method.
It does not reach the display performance of.

JP-A-4-229828, JP-A-4-4-2
As disclosed in Japanese Patent No. 58923, a method has been proposed in which a viewing angle is increased by disposing a retardation film between a pair of polarizing plates and a TN type liquid crystal cell.

[0006] The retardation film proposed in the above-mentioned patent publication has almost zero retardation in the direction perpendicular to the liquid crystal cell, does not exert any optical action from directly in front of the liquid crystal cell, and is tilted when tilted. Then, a phase difference is developed, and the phase difference developed in the liquid crystal cell is to be compensated. However, even with these methods, the viewing angle of the LCD is still insufficient, and further improvement is desired. Especially for in-vehicle and CR
When considered as an alternative to T, it is impossible at present to cope with the current viewing angle. Also, Japanese Patent Application Laid-Open No. Hei 4-366
808 and JP-A-4-366809, a viewing angle is improved by using a liquid crystal cell containing a chiral nematic liquid crystal having an inclined optical axis as a retardation film.
It is a layer liquid crystal system, which is expensive and very heavy.

Further, Japanese Patent Application Laid-Open No. 5-80323 proposes a method of using a retardation film whose optical axis is inclined with respect to a liquid crystal cell. Therefore, there is a problem that it is difficult to obtain a large-area retardation film at low cost.

Further, Japanese Patent Application No. 5-5823 discloses a method using a retardation film whose optical axis is inclined using a photoisomerizable substance. According to this method, a lightweight, low-cost liquid crystal display device having a wide viewing angle characteristic can be realized. However, a disadvantage of this method is that the stability of the retardation film against heat and light is not sufficient.

[0009]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to improve a narrow viewing angle characteristic resulting from the fact that the polarization state of light propagating in a liquid crystal cell varies depending on the incident direction, and to further improve heat and light. Another object of the present invention is to provide a method for manufacturing an optical compensatory sheet having improved durability, and a method for manufacturing an optical compensatory sheet capable of easily and inexpensively producing a large-area homogeneous thin film.

[0010]

According to the present invention, a discotic liquid crystalline compound or a mixture thereof is coated on the surface of an alignment film provided on a support and subjected to a heat treatment to provide a discotic nematic phase or a uniaxial phase. After forming the columnar phase, cooling is performed to form a monodomain thin film of any of these phases. Production of an optical compensatory sheet in which the optical axis is inclined by 5 to 50 degrees from the normal direction of the surface. In the way. The discotic liquid crystalline compound preferably has a triphenylene carbon skeleton in its partial structure.

The discotic liquid crystalline compound is preferably a compound represented by the following general formula (I).

[0012]

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Wherein R is a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted alkanoyl group, a substituted alkenoyl group, a substituted alkinoyl group, a substituted or unsubstituted aryloyl group, a substituted or unsubstituted aryloyl group, Represents a substituted alkoxycarbonyl group, a substituted or unsubstituted aryloxycarbonyl group, a substituted carbamoyl group or a substituted sulfamoyl group, and each R may be the same or different. The R in the general formula (I) is, ^{Z 3} of ^{Z 2,} the general formula of the following general formula ^{(II) (III), Z} 5, general formula ^{Z 4,} of the general formula (IV) (V) Z ^{6 in} (VI) and the general formula (VI)
^{Z 7} of I), ^{Z 8} of the general formula (VIII) or is preferably represented by ^{Z 9} of the general formula (IX),.

General formula (II) Z ² = -CO-CR ²¹ = CR ²² -C ₆ H _5-n -R ²³ _{n wherein} R ²¹ and R ²² are each a hydrogen atom, a halogen atom, a substituted or unsubstituted R ²³ represents a halogen atom, a cyano group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted alkoxy group, Represents an unsubstituted aryloxy group, the n substituents of which may be the same or different;
n represents 0, an integer of 1 to 5;

General formula (III) Z ³ = -CO- (CR ³¹ R ³² ) _m- (Y) _p -C ₆ H _5-n -R ³³ _{n wherein} R ³¹ and R ³² are a hydrogen atom, a halogen atom Represents a substituted or unsubstituted alkyl group, Y represents an oxygen atom or a sulfur atom, and R ³³ represents a halogen atom, a cyano group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, Represents an unsubstituted aryl group, a substituted or unsubstituted alkoxy group, or a substituted or unsubstituted aryloxy group, and the n substituents may be the same or different. m represents an integer of 1 to 4, p represents 0 or 1, and n represents 0 or an integer of 1 to 5.

General formula (IV) Z ⁴ =-(CR ⁴¹ R ⁴² ) _m- (CR ⁴⁴ = CR ⁴⁵ ) _p -C ₆ H _5-n -R ⁴³ _n where R ⁴¹ , R ⁴² , R ⁴⁴ , R ⁴⁵ represents a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, and R ⁴³ represents
A halogen atom, a cyano group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted aryloxy group, The n substituents may be the same or different. m represents an integer of 1 to 5, p represents 0, 1 or 2, and n represents 0 or an integer of 1 to 5.

General formula (V) Z ⁵ =-(CR ⁵¹ R ⁵² ) _m -CO-C ₆ H _5-n -R ⁵³ _{n wherein} R ⁵¹ and R ⁵² are a hydrogen atom, a halogen atom, substituted or unsubstituted R ⁵³ is a halogen atom, a cyano group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted alkoxy group,
Represents a substituted or unsubstituted aryloxy group;
Substituents may be the same or different from each other. m represents an integer of 1 to 4; n represents 0 or an integer of 1 to 5;

General formula (VI) Z ⁶ = —CO—C ⁶ H _11-n —R ⁶³ _n wherein R ⁶³ is a hydrogen atom, a halogen atom, a cyano group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted A cycloalkyl group, a substituted or unsubstituted aryl group,
Represents a substituted or unsubstituted alkoxy group or a substituted or unsubstituted aryloxy group, the n groups may be the same or different from each other, and n is 0 to 11
Represents an integer.

Formula (VII) Z ⁷ = —CO—C ₆ H _5-n —R ⁷ _{n wherein} R ⁷ is a halogen atom, a cyano group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cyclo group. Represents an alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted alkoxy group, or a substituted or unsubstituted aryloxy group, and the n substituents may be the same or different. n represents 0 or an integer of 1 to 5.

Formula (VIII) Z ⁸ Ｚ—CO—R ^{8 wherein} R ⁸ is a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, a substituted or unsubstituted group. Represents a heterocyclic residue.

Formula (IX) Z⁹= -R⁹  Where R⁹Is a substituted or unsubstituted alkyl group,
Or an unsubstituted alkenyl group or a substituted or unsubstituted
Represents a substituted alkynyl group.

Hereinafter, the present invention will be described in detail. The discotic liquid crystal phase is a general term for the liquid crystal phase formed by the discotic molecules, and details thereof are described in a research report by C. Destrade et al. (Mol.
Cryst. Liq. Cryst. Vol. 71, p. 111 (1981)], a columnar phase in which the central cores of disk-shaped molecules are stacked in a columnar manner by intermolecular force.
It is known that discotic molecules can be roughly classified into a discotic nematic phase in which discotic molecules are randomly aggregated, and a chiral discotic nematic phase. But WHde j
eu's Physical properties of liquid crystalline ma
terials (1980 by Gordon and Breach, Science Pu
As described in blishers), columnar phases are often found, but the discotic nematic phases used in the present invention are rarely found.

The fact that the triphenylene discotic liquid crystal of the present invention has negative birefringence was reported by B. Mourey et al. [Mol. Cryst. Liq. Cryst., 84, 193 (19).
1982)], but in order to apply this property as an optical compensation sheet, it is necessary to arrange all the molecules constituting the thin film statistically in one direction at room temperature. In addition, the discotic liquid crystal is microscopically composed of an alignment region (domain) having a specific direction, and does not macroscopically exhibit optical anisotropy, similarly to a conventional liquid crystal composed of rod-like molecules. Due to the nature of forming a so-called multi-domain, in many cases the thin film does not exhibit favorable optical properties that can be used for an optical compensatory sheet.

In this regard, we have studied in detail various discotic liquid crystals, and have found that a discotic nematic liquid crystal phase or a liquid crystal forming a uniaxial columnar phase, especially a triphenylene-based liquid crystal represented by the following general formula (I), It has been found that a thin film of a compound having a carbon skeleton structure has preferable characteristics as an optical compensation sheet.
Furthermore, it was found that a thin film in which a discotic nematic liquid crystal phase or a uniaxial columnar phase was formed preferentially tends to be in a monodomain state, and high light transmittance and high contrast are easily obtained. Although it is possible to use it as an optical compensatory sheet without realizing a complete monodomain state, it was found that a more complete monodomain thin film is preferable in terms of optical characteristics, productivity, etc. Was completed.

Further, it is preferable that the compound having the triphenylene-based carbon skeleton structure has a structure substituted at the substitution position as represented by the above general formula (I).

The substituents R in the general formula (I) may be the same or different from each other.
Compounds having a structure represented by any one of the substituents Z ^{2 to} Z ⁹ of I) to (IX) are preferred.

Further, 2,3,6,7,
The 10,11-substituted triphenylene compound is available from Macromo
l. Chem. Rapid Communication., vol. 4, p. 812 (1
983) to give a 6-methoxy-substituted product by oxidative trimerization of 1,2-dimethoxybenzene. The synthesis method described in Advanced Materials. Vol. 2, p. 40 (1990) can also be used.

Hereinafter, specific examples of the triphenylene compound and its side chain used in the present invention will be described, but the present invention is not limited by these compounds.

[0029]

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[0030]

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[0031]

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[0032]

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[0033]

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[0034]

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[0035]

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[0036]

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[0037]

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The optical compensatory sheet obtained by the present invention comprises:
An alignment film (protective film) is provided on a support, and a discotic liquid crystal layer is provided thereon. Depending on the application, a protective film or a support exists on the liquid crystal layer or between the liquid crystal layers. Is also good.

The discotic liquid crystal constituting the optical compensation sheet obtained according to the present invention may be used alone or as a mixture. In particular, the adjustment of the phase transition temperature, the control of the optical structure of the liquid crystal phase, the improvement of the film forming property, and the like are often performed effectively by appropriately mixing the liquid crystal.

It is desirable that the material of the support be close to optically isotropic in addition to having good light transmittance. Therefore,
A support made of a material having a small intrinsic birefringence value sold under the trade name of glass, Zeonex (Zeon Corporation of Japan), ARTON (Japan Synthetic Rubber), Fujitac (Fuji Film) or the like is preferable. However, even if the material has a large intrinsic birefringence value such as polycarbonate, polyacrylate, and polysulfone, it is also possible to form an optically isotropic support by controlling the molecular orientation during film formation, They are also preferably used.

Examples of the material for the protective film include polymethyl methacrylate, acrylic acid / methacrylic acid copolymer, styrene / maleic anhydride copolymer, polyvinyl alcohol, N-methylol acrylamide, styrene
Vinyl toluene copolymer, chlorosulfonated polyethylene, nitrocellulose, polyvinyl chloride, chlorinated polyolefin, polyester, polyimide, vinyl acetate / vinyl chloride copolymer, ethylene / vinyl acetate copolymer, polyethylene, polypropylene, polycarbonate, etc. And organic substances such as a silane coupling agent. In addition, a Langmuir-Blodgett method (LB) such as ω-tricosanoic acid, dioctadecyldimethylammonium chloride and methyl stearate is used.
) Can also be used.

It is a well-known fact in the case of rod-shaped liquid crystals that the provision of an alignment film (protective film) often has a large effect on the molecular alignment during the formation of the liquid crystal layer. Membranes are almost always used.
This is one of the techniques preferably used in the present invention, and the alignment film (protective film) provided on the support is:
Typical examples thereof include a SiO obliquely vapor-deposited metal film and a rubbed fluorinated polyimide film of an organic alignment film.

In the method for producing an optical compensation sheet of the present invention,
A general coating method can be used. That is, a liquid crystal thin film can be formed on a support through a drying step by a coating method such as spray coating, spin coating, dip coating, curtain coating, and extrusion coating. Since the properties of the liquid crystal of the present invention are significantly different depending on the structure of the side chain, the solvent and the concentration to be used cannot be specifically limited.However, considering the uniformity of the thin film, it is preferable to use a solvent having high solubility, , Halogen compounds such as chloroform, acetone, ketones such as methyl ethyl ketone, esters such as ethyl acetate, dimethylacetamide, dimethylformamide, amides such as N-methyl-pyrrolidone and isopropanol,
Alcohols such as perfluoropropanol are preferably used. In particular, in the liquid crystal of the present invention, it was often observed that the optical axes tended to be aligned in the application direction at this coating stage.

Therefore, the manufacturing method of the present invention is performed as follows. At least one interface is in contact with the gas phase,
That is, the liquid crystal thin film is formed on a suitable support by a general coating method, dried, and then heat-treated for a predetermined time at a temperature within a liquid crystal phase formation temperature range while forming a discotic nematic phase or a uniaxial columnar phase. Then, by cooling, an optical compensatory sheet whose optical axis is inclined by 5 to 50 degrees from the normal direction of the surface can be obtained.

Hereinafter, the operation of the optical compensation sheet of the present invention will be described with reference to the drawings, taking a TN type liquid crystal display element as an example. 1 and 2 show the polarization state of light propagating through the liquid crystal cell when a sufficient voltage equal to or higher than the threshold voltage is applied to the liquid crystal cell. Since the light transmittance characteristics at the time of applying a voltage greatly contribute to the viewing angle characteristics of the contrast,
A description will be given of an example in which a voltage is applied. FIG. 1 is a diagram illustrating a polarization state when light is vertically incident on a liquid crystal cell. When the natural light L0 is perpendicularly incident on the polarizing plate A having the polarizing axis PA, the light transmitted through the polarizing plate PA becomes linearly polarized light L1.

When the arrangement state of liquid crystal molecules when a sufficient voltage is applied to the TN type liquid crystal cell is schematically shown by one liquid crystal molecule as a model, it becomes LC in the schematic diagram. When the molecular long axis of the liquid crystal molecules LC in the liquid crystal cell LCS is parallel to the light path, there is no difference in the refractive index on the incident surface (in a plane perpendicular to the light path), so that the light propagates through the liquid crystal cell. There is no phase difference between the ordinary light and the extraordinary light, and the linearly polarized light that has passed through the LC cell propagates as a linearly polarized light even though it passes through the liquid crystal cell. When the polarization axis PB of the polarizing plate B is set perpendicular to the polarization axis PA of the polarizing plate A, the light passes through the liquid crystal cell and the other linearly polarized light L2 cannot pass through the polarizing plate B, resulting in a dark state.

FIG. 2 is a diagram showing the polarization state of light when the light is obliquely incident on the liquid crystal cell. Natural light L of incident light
When 0 is obliquely incident, the polarized light L1 transmitted through the polarizing plate A
Becomes almost linearly polarized light (in practice, it becomes elliptically polarized light due to the characteristics of the polarizing plate). In this case, the refractive index anisotropy of the liquid crystal causes a difference in the refractive index on the incident surface of the liquid crystal cell, and the light L2 transmitted through the liquid crystal cell is elliptically polarized and is not completely blocked by the polarizing plate B. As described above, in oblique incidence, light is not sufficiently blocked in a dark state, which causes a significant decrease in contrast, which is not preferable.

The present invention aims to prevent such a decrease in contrast at oblique incidence and improve the viewing angle characteristics. FIG. 3 shows an example of the configuration according to the present invention. An optically anisotropic element RF having an optical axis inclined from the normal direction of the liquid crystal cell is disposed between the polarizing plate B and the liquid crystal cell.
The optically anisotropic element RF is a birefringent body that polarizes as the angle of incidence of light with respect to the optical axis increases. As in the case of FIG. 2, the elliptically polarized light L2 transmitted obliquely to the liquid crystal display element having such a configuration and transmitted through the liquid crystal cell as in the case of FIG. Thus, a favorable liquid crystal display element having no viewing angle dependence and having the same transmittance even at various oblique incidences can be realized.

It is presumed as follows that the viewing angle of the liquid crystal display device can be greatly improved by the present invention. Many TN-LCDs employ a normally white mode. In this mode, as the viewing angle is increased, the transmittance of light from the black display section is significantly increased, resulting in a sharp decrease in contrast. The black display is the state when voltage is applied,
At this time, the TN type liquid crystal cell can be regarded as a positive uniaxial optically anisotropic body whose optical axis is slightly inclined from the normal direction to the surface of the cell. In the case of the intermediate gradation, it is considered that the optical axis is further inclined from the normal direction of the LC cell.

When the optical axis of the liquid crystal cell is inclined from the direction normal to the surface of the liquid crystal cell, compensation is expected to be insufficient with an optically anisotropic body whose optical axis is in the direction of the normal. If the liquid crystal cell can be regarded as a positive uniaxial optically anisotropic body, a negative uniaxial optically anisotropic body is preferable in order to compensate for it. For such a reason, it is presumed that the viewing angle characteristics have been greatly improved by the negative uniaxial optical anisotropic material whose optical axis is inclined from the normal direction in the present invention.

The term “negative uniaxiality” in the present invention refers to a relation of nα <nβ = nγ, where nα, nβ, and nγ are three-dimensional refractive indexes of a sheet having optical anisotropy in ascending order. Have Therefore, it has the characteristic that the refractive index in the optical axis direction is the smallest. However, the values of nβ and nγ do not need to be exactly equal, but it is sufficient if they are approximately equal. Specifically, | nβ-nγ | / | nβ-nα
If | <0.2, there is no practical problem. TFT, T
As a condition for greatly improving the viewing angle characteristics of the N-type liquid crystal cell, the optical axis is preferably inclined at 5 to 50 degrees from the normal direction of the sheet surface, more preferably 10 to 40 degrees, and more preferably 10 degrees. ~ 30 degrees is most preferred. Furthermore, when the thickness of the sheet is D, 100 <(nβ−nα) × D <400
It is desirable to satisfy the condition of nm.

Synthesis Example 1 Synthesis of Liquid Crystal Compound TP-1 1-a) Synthesis of 2,3,6,7,10,11-hexamethoxytriphenylene (a) In a two-liter ice-cooled three-necked flask, 135m ice water
l, and with vigorous stirring with a mechanical stirrer,
490 ml of concentrated sulfuric acid was gradually added. Next, at room temperature,
50 g of ferric chloride were added and after 1 hour, a further 1,2
30 g of dimethoxybenzene were added. After 3 hours, the mixture was cooled with ice, 1 liter of ice water was gradually added, and after 1 hour, the reaction mixture was filtered through a glass filter to obtain crude crystals 1 of the desired product.
3 g (43%) were obtained.

1-b) 2,3,6,7,10,11-
Synthesis of hexahydroxytriphenylene (b) 10.3 g of a was suspended in 50 ml of dichloromethane, and 15.5 ml of boron tribromide was gradually added. Two hours later, the mixture was poured into 500 ml of ice water, extracted with 2.5 liters of ethyl acetate, dried over anhydrous sodium sulfate, and filtered through celite. After the solvent was concentrated under reduced pressure, the residue was recrystallized from a mixed solvent of acetonitrile and dichloromethane to obtain 7.50 g (92%) of the desired product.

1-c) Synthesis of 4-heptyloxybenzoic acid (c) In a 1-liter three-necked flask, 35.0 g of ethyl 4-hydroxybenzoate, 54.6 g of heptyl bromide, 150 g of potassium carbonate and 100 ml of acetonitrile It was placed,
The mixture was stirred vigorously with a mechanical stirrer for 6 hours while heating and refluxing on a hot water bath. After cooling, the reaction mixture was filtered through celite, and the residue was washed with 300 ml of ethyl acetate. After concentration under reduced pressure,
It was redissolved in 200 ml of ethanol, and 40 ml of an aqueous solution in which 15.0 g of potassium hydroxide was dissolved was gradually added dropwise.
The mixture was heated and stirred at 80 ° C. for 1 hour. After cooling, the precipitated crystals were filtered under reduced pressure, and the residue was washed with 100 ml of ethanol.
The mixture was stirred in 300 ml of diluted hydrochloric acid at 40 ° C. for 1 hour, filtered under reduced pressure and dried to obtain 40.0 g (80%) of the desired product.

1-d) 2,3,6,7,10,11-
Synthesis of hexa (4-heptyloxybenzoyloxy) triphenylene (TP-1) 8.34 g of c and 10 ml of thionyl chloride were placed in a 200 ml flask, and heated under reflux for 2 hours. While heating, excess thionyl chloride was distilled off under reduced pressure. After cooling,
0.70 g of b and 20 ml of pyridine were added, and the mixture was stirred with heating under reflux for 20 hours. After cooling, excess pyridine was distilled off under reduced pressure, and the desired product was purified and isolated by silica gel column chromatography. Yield 3.05 g (75%)

NMR (measurement solvent CDCl ₃ ) δ 0.92 (18H, t) δ 1.35 (48H, m) δ 1.78 (12H, m) δ 3.90 (12H, t) δ 6.65 (12H, d) δ 7.90 (12H, d) δ 8.37 (6H, s) Phase transition temperature measurement by DSC and polarizing microscope observation Crystalline phase-169 ° C-Discotic nematic phase-
257 ° C-isotropic liquid phase

Synthesis Example 2: Synthesis of liquid crystal compound TP-2 1-e) Synthesis of 4-heptyloxycinnamic acid (e) 15.5 g of 4-hydroxycinnamic acid, heptyl bromide 30.
0 g and 50.0 g of potassium carbonate were suspended in 50 ml of dimethyl sulfoxide, and heated on a hot water bath for 10 hours while vigorously stirring with a mechanical stirrer. After cooling, the mixture was filtered through celite, and the residue was washed with 300 ml of ethyl acetate. 500 ml of water was added thereto, and after extraction, the organic layer was concentrated under reduced pressure. 100 ml of ethanol was added thereto, and 20 ml of an aqueous solution containing 10 g of potassium hydroxide was added.
Stirred for hours. After cooling, the precipitated crystals were filtered under reduced pressure, and the residue was washed with 100 ml of ethanol. The mixture was stirred in 300 ml of dilute hydrochloric acid at 40 ° C. for 1 hour, filtered under reduced pressure and dried to obtain 19.1 g (78%) of the desired product.

1-f) 2,3,6,7,10,11-
Synthesis of hexa (4-heptyloxycinnamoyloxy) triphenylene (TP- 2 ) 10.4 g of e and 10 ml of thionyl chloride were placed in a 200 ml flask, and heated under reflux for 2 hours. While heating, excess thionyl chloride was distilled off under reduced pressure. After cooling,
0.70 g of b and 20 ml of pyridine were added, and the mixture was stirred with heating under reflux for 20 hours. After cooling, excess pyridine was distilled off under reduced pressure, and the target product was purified by silica gel column chromatography, and then recrystallized with a mixed solvent of acetonitrile and acetone. Yield 3.55 g (90%)

NMR (measurement solvent CDCl ₃ ) δ 0.92 (18H, t) δ 1.35 (48H, m) δ 1.78 (12H, m) δ 3.90 (12H, t) δ 6.50 (6H, d) δ 6.65 (12H, d) δ 7.25 (12H, d) δ 7.83 (6H, d) δ 8.20 (6H, s) Phase transition temperature measurement by DSC and polarizing microscope observation Crystal phase -155 ° C-discotic Nematic phase-
252 ° C-isotropic liquid phase

[0060]

【Example】

(Preparation of Optical Compensation Sheet) A 10% dichloromethane solution of TP-2 was applied and dried on a SiO oblique deposition film having a tilt angle of 45 ° and a film thickness of about 400 Å formed on a glass substrate. In this state, the film was cloudy.
After heating at 0 ° C. for 10 minutes and cooling to room temperature, a colorless and transparent film was formed. When observed with a polarizing microscope,
No disclination line indicating the disorder of the molecular orientation in the film was observed, indicating that an optically monodomain homogeneous film was formed.

(Evaluation of Performance) The measurement was performed using an ellipsometer (AEP-10) manufactured by Shimadzu Corporation.
0) was set to the transmission mode to determine the angle dependence of the retardation, and from these values, the optimum triaxial refractive index and the direction of the optical axis were calculated. The product of the difference between the refractive index of the extraordinary light and the ordinary light of the crystal and the gap size of the liquid crystal cell is 480 nm, and the optical compensation sheet prepared above is attached to the TN type liquid crystal cell having a twist angle of 90 degrees. 0-5V 30H
Otsuka Electronics: Angular dependence of contrast in z square wave
It was measured by LCD-5000 manufactured by Co., Ltd. The position of the contrast 10 was defined as the viewing angle, and the up, down, left, and right viewing angles were determined. Et al is, after leaving the LCD 500 hours, at 50 ° C., was measured in the vertical direction of the viewing angle characteristics. The results are shown in the table below. Incidentally, the polarization axis of the polarizing plate of the TN liquid crystal cell in this measurement, the rubbing axis of the liquid crystal cell, the direction of the optical axis <br/> optical compensation sheet is shown in FIG.

Optical Compensation Sheet Viewing Angle Characteristics (0 hr) Viewing Angle Characteristics (500 hr) Up-Down Right-Left Up-Down Yes 46-48 52-55 43-47 No 23-27 33-36 23-27

As is apparent from the above figure, in the LCD provided with the optical compensation sheet of the present invention, a remarkable improvement in the viewing angle characteristics has been achieved. In addition, the long-term storage stability is very excellent.

[0064]

According to the present invention, the viewing angle characteristic of the TN type liquid crystal display device is improved, and a high quality display device having excellent visibility can be provided, and a high quality image can be stably provided for a long period of time. You can do it. Further, the present invention relates to a TFT or MIN.
It goes without saying that excellent effects can be obtained even when applied to an active matrix liquid crystal display device using three terminals and two terminals.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of a conventional TN-type liquid crystal display device and a diagram illustrating a light transmission state when light is vertically incident on a display surface.

FIG. 2 is a diagram illustrating a configuration of a conventional TN-type liquid crystal display device and a diagram illustrating a light transmission state when light is obliquely incident on a display surface.

FIG. 3 is a diagram for explaining an embodiment of the configuration of the liquid crystal display element of the present invention.

FIG. 4 is a view showing an optical axis direction of a liquid display element used in the present embodiment.

[Explanation of symbols]

A, B: Polarizing plate PA, PB: Polarizing axis LCS: TN type liquid crystal cell RF: Optically anisotropic element LO: Incident light L1: Linearly polarized light passing through polarizing plate A L2: Polarized light passing through TN type liquid crystal cell ( LC: Model representation of liquid crystal in TN liquid crystal cell θ: Incident angle of linearly polarized light

──────────────────────────────────────────────────の Continuation of the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location // C08J 5/18 CEZ C08J 5/18 CEZ (56) References JP-A-2-304526 (JP) JP-A-2-111918 (JP, A) JP-A-4-349424 (JP, A) JP-A-60-231787 (JP, A) JP-A-56-90878 (JP, A) 4-113301 (JP, A) JP-A-4-120512 (JP, A) JP-A-5-215921 (JP, A) International Publication 90 / 1,605 (WO, A) International Publication 95/14652 (WO, A) Published German Patent Application 3911620 (DE, A) PHYSICS LETTERS 72 A (3) (1979) 251-254

Claims (4)

(57) [Claims] 1. A discotic liquid crystalline compound or a mixture thereof is coated on the surface of an alignment film provided on a support, heat-treated to form a discotic nematic phase or a uniaxial columnar phase, and then cooled. Then, a method for producing an optical compensatory sheet in which an optical axis formed by forming a monodomain thin film of any of these phases is inclined by 5 to 50 degrees from the normal direction of the surface. 2. The method for producing an optical compensatory sheet according to claim 1, wherein the discotic liquid crystalline compound has a triphenylene carbon skeleton in its partial structure. 3. The method for producing an optical compensatory sheet according to claim 1, wherein the discotic liquid crystalline compound is represented by the following general formula (I). Embedded image However, R is a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted alkanoyl group, a substituted alkenoyl group, a substituted alkinoyl group,
Represents a substituted or unsubstituted aryloyl group, a substituted or unsubstituted alkoxycarbonyl group, a substituted or unsubstituted aryloxycarbonyl group, a substituted carbamoyl group or a substituted sulfamoyl group, and each R may be the same or different. Good. 4. The compound of the formula (I) wherein R is
Z of (II)², Z of the general formula (III)³, The general formula (I
V) Z⁴, Z of the general formula (V)⁵, Z of the general formula (VI)
⁶, Z of the general formula (VII)⁷, Z of the general formula (VIII)
⁸Or Z of the general formula (IX)⁹Claim 3 represented by
3. The method for producing an optical compensation sheet according to item 1.Where R²¹And R²²Are hydrogen and halogen
A substituted or unsubstituted alkyl group;
²³Is a halogen atom, a cyano group, a substituted or unsubstituted
An alkyl group, a substituted or unsubstituted cycloalkyl group,
Substituted or unsubstituted aryl group, substituted or unsubstituted
An alkoxy group or a substituted or unsubstituted aryl
Represents a xy group;²³N groups represented by
May be the same or different, and n is an integer from 0 to 5
Represents General formula (III)Where R³¹And R³²Are hydrogen and halogen
And represents a substituted or unsubstituted alkyl group;
Represents an oxygen atom or a sulfur atom;³³Is halogen
Atom, cyano group, substituted or unsubstituted alkyl group,
Substituted or unsubstituted cycloalkyl group, substituted or unsubstituted
Substituted aryl group, substituted or unsubstituted alkoxy group
Or a substituted or unsubstituted aryloxy group
Then R³³N groups represented by
M is an integer of 1 to 4, and p is 0
Or 1 and n represents an integer from 0 to 5
You. General formula (IV)Where R⁴¹, R⁴², R⁴⁴And R⁴⁵Is hydrogen
Atom, halogen atom or substituted or unsubstituted alkyl
And represents R⁴³Is a halogen atom, cyano group, substituted
Or an unsubstituted alkyl group, a substituted or unsubstituted
Chloroalkyl group, substituted or unsubstituted aryl group,
Substituted or unsubstituted alkoxy group or substituted or unsubstituted
R represents a substituted aryloxy group;⁴³Represented by
The n groups may be the same or different and m is 1
Represents an integer of ５5, p represents 0, 1 or 2;
And n represents an integer of 0 to 5.Where R⁵¹And R⁵²Are hydrogen and halogen
A substituted or unsubstituted alkyl group;
⁵³Is a halogen atom, a cyano group, a substituted or unsubstituted
An alkyl group, a substituted or unsubstituted cycloalkyl group,
Substituted or unsubstituted aryl group, substituted or unsubstituted
An alkoxy group or a substituted or unsubstituted aryl
Represents a xy group;⁵³N groups represented by
M may be the same or different, and m represents an integer of 1 to 4
And n represents an integer from 0 to 5. General formula (VI) Z⁶= -CO-C₆H_11-n-R⁶³ _n Where R⁶³Represents a hydrogen atom, a halogen atom, a cyano group,
Substituted or unsubstituted alkyl group, substituted or unsubstituted
A cycloalkyl group, a substituted or unsubstituted aryl group,
A substituted or unsubstituted alkoxy group or a substituted or
Represents an unsubstituted aryloxy group;⁶³Represented by
N groups may be the same or different from each other, and
And n represents an integer of 0 to 11. General formula (VII) Z⁷= -CO-C₆H_5-n-R⁷ _n Where R⁷Represents a halogen atom, a cyano group,
Substituted alkyl group, substituted or unsubstituted cycloalkyl
Group, a substituted or unsubstituted aryl group,
Unsubstituted alkoxy group or substituted or unsubstituted ant
Represents a hydroxy group, R⁷N groups represented by
Can be the same or different, and n is 0-5
Represents an integer. General formula (VIII) Z⁸= -CO-R⁸  Where R⁸Is a substituted or unsubstituted alkyl group,
Or an unsubstituted alkenyl group, a substituted or unsubstituted
An alkynyl group or a substituted or unsubstituted heterocyclic residue
Express. General formula (IX) Z⁹= -R⁹  Where R⁹Is a substituted or unsubstituted alkyl group,
Or an unsubstituted alkenyl group or a substituted or unsubstituted
Represents a substituted alkynyl group.