JPH0534678A - Visual angle compensation plate for liquid crystal display element - Google Patents

Abstract

PURPOSE:To lessen the dependency on visual angles possessed by a liquid crystal display by consisting the compensation plate of specific liquid crystlline polyester. CONSTITUTION:This compensation plate consists of a light transparent substrate and a film consisting of the liquid crystalline polyester which is formed on this substrate, has the structure having the refractive index in the thickness direction larger than the refractive index in at least one direction within the plane in a liquid crystal state, turns to a glassy state at the temp. below the liquid crystal transition point and consists of the constitutional units of formula I, formula II and if desired, formula III. In the formulas I to III, X denotes a specific bivalent group contg. an arom. group; Y denotes a bivalent aliiphat. group contg. at least one asymmetrical carbon atom and having 3 to 12C; Z denotes a straight chain or branched bivalent aliiphat. group having 3 to 12C and an odd number of the carbon atoms of the part constituting the main chain of the polymer. The formula I exists at 40 to 60mol% ratio in the polymer, the formula II at 1 to 60mol% and the formula III at 0 to 59mol%. Theoretically, these ratios are preferably such that the total amt. of the formula II and the formula III is nearly equal to the equiv. molar amt. of the formula I.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a viewing angle compensator for a liquid crystal display device, which can reduce the viewing angle dependence of a liquid crystal display.

[0002]

2. Description of the Related Art Liquid crystal displays are low-voltage driven, lightweight,
Because of its low cost and other features, it is occupying a major position in the display field in place of cathode ray tubes. However, since the liquid crystal display is a method of displaying an image by utilizing the alignment behavior of a liquid crystalline substance having optical stereoscopic anisotropy, the problem that the color tone of the screen changes depending on the viewing direction of the panel It is essentially unavoidable. This viewing angle dependency becomes more remarkable when a color compensation optical element such as a stretched film or a liquid crystal cell is mounted on the liquid crystal display. For example, a laptop personal computer using a twisted nematic mode (hereinafter abbreviated as TN) or a super twisted nematic mode (hereinafter abbreviated as STN) or a word processor display has a relatively good image when viewed from the front. However, if viewed from a direction other than the front, the screen may be colored or the image may be difficult to see. Not only is the viewing angle dependence of such a display not preferred by users, but it is also not possible to cope with the large screen required for wall-mounted televisions and the like. That is, in the case of a large-screen display, as long as the conventional technique is used, a clear image cannot be obtained over the entire screen because the peripheral portion has a certain viewing angle even when viewed from the front.

It has been suggested that a film having a refractive index in the thickness direction larger than the in-plane refractive index is effective as a means for reducing the viewing angle dependence of such a display (M. Akatuka et al .: Japan). D
isplay '89, 336 (1989)), there are practically no such films, and even if there is such a film, the difference between the refractive index in the thickness direction and the in-plane refractive index is at most 0.00.
It is about 1 (Japanese Patent Laid-Open No. 3-85519), and no remarkable effect of improving the viewing angle dependency is obtained. Liquid crystalline substances are promising as substances with large refractive index anisotropy, but it has been said that it is difficult to maintain stable orientation in low molecular weight liquid crystals, while it is generally impossible to obtain uniform orientation in polymer liquid crystals. .

[0004]

The present inventors have focused on a polymer liquid crystal film having a large refractive index in the thickness direction in order to reduce the viewing angle dependence of a liquid crystal display, and have proposed a new liquid crystal satisfying this condition. As a result of conducting a search for organic polymers and conducting diligent studies, a group of liquid crystalline polymer films including an antiferroelectric liquid crystal (Japanese Patent Application No. Hei 2-331622) previously proposed by the present inventors was found to have a thickness direction. They have found that a structure having a large refractive index can be obtained, and finally reached the present invention. An object of the present invention is to provide a compensator for a liquid crystal display device, and particularly to provide a viewing angle compensator for a liquid crystal display using a liquid crystalline polyester film having an orientation fixed.

[0005]

That is, according to the present invention, a translucent substrate, and a refractive index in a thickness direction in a liquid crystal state formed on the substrate is larger than a refractive index in at least one in-plane direction. Structural units (A) and (B) represented by the following general formula that have a structure and become a glass state at a temperature below the liquid crystal transition point.
And a viewing angle compensating plate for a liquid crystal display device, which is composed of a film made of liquid crystalline polyester consisting of (C) if desired.

[0006]

[Chemical 5]

[0007]

[Chemical 6] Which represents one or more structural units selected from the group consisting of: (B) —O—Y—O— 1 to 60 mol% [wherein Y contains at least one asymmetric carbon atom and has 3 to 12 carbon atoms] Shows a certain divalent aliphatic group] (C) -O-Z-O-0 to 59 mol% [wherein Z has 3 to 12 carbon atoms and the carbon number of the portion constituting the main chain of the polymer is Shows an odd-numbered linear or branched divalent aliphatic group]

The present invention also relates to the viewing angle compensator for a liquid crystal display device, wherein the liquid crystalline polyester is homeotropically aligned in a liquid crystal state, and the present invention is also directed to the structural unit (A) represented by the general formula. ), (B) and optionally (C) are heat-treated on the substrate at a temperature not lower than the glass transition point of the liquid crystalline polymer and then at a temperature not higher than the glass transition point of the liquid crystalline polymer. The present invention relates to a viewing angle compensating plate for a liquid crystal display element, which is formed by using a film having a structure in which the structure is cooled and the refractive index in the thickness direction is larger than the refractive index in at least one direction in the plane.

The present invention will be described in detail below. Explaining the structural components constituting the liquid crystalline polyester used in the present invention, first, the general formula

[0010]

[Chemical 7]

The structural unit ((A) unit) represented by is an essential component which plays a role as a mesogen for exhibiting liquid crystallinity, and a dicarboxylic acid (HOOC-X-COO).
H) or its derivatives (eg dialkyl esters,
Acid chloride). The (A) unit is present in the polymer in a proportion of 40 to 60 mol%, preferably 4
It is 5 to 55 mol%, and particularly preferably substantially 50 mol%. The X groups in the formula include the following.

[0012]

[Chemical 8]

[0013]

[Chemical 9]

One or more of these in the polyester molecule,
Preferably, one kind or two kinds are present. Further, a substituted structural unit in which at least one, preferably one or two, of hydrogen atoms of the aromatic ring of the structural unit is substituted with an alkyl group, an alkoxy group, a halogen atom or a halogenated alkyl group having 4 or less carbon atoms is also used. be able to. Examples of such a substituted structural unit include:

[0015]

[Chemical 10] And so on. Among these, as the X group in the formula, particularly preferable are:

[0016]

[Chemical 11]

The structural unit ((B) unit) represented by the general formula —O—Y—O— is an essential component for the polyester used in the present invention to exhibit liquid crystallinity and to fix the liquid crystal state. And a component containing at least one asymmetric carbon atom. The (B) unit is a corresponding diol (HO-
Y-OH) or a derivative thereof (for example, a derivative such as a diacetoxy compound).

The Y group in the formula is a divalent aliphatic group having at least one asymmetric carbon atom and having 3 to 12 carbon atoms, for example, having 2 to 12 carbon atoms in the main chain, preferably Two
A part of the hydrogen atoms of the alkylene group of 1 to 6 are substituted with an alkyl group having 1 to 4 carbon atoms (however, the total number of carbon atoms of the Y group is 3 to 12) or a halogen atom (in this case, the main chain is 3 to 12). And having an asymmetric carbon atom. In particular,

[0019]

[Chemical 12]

When the carbon number of the Y group is 2 or less or 13 or more, good orientation cannot be obtained. The diols used may be either R-form or S-form, or a mixture of both. In the case of the mixture, the difference in content ratio between the R form and the S form may be arbitrary, that is, may be in the range of 0 to 100%. Generally, depending on the film thickness, when the difference is not 0, the film after orientation and fixation tends to have a helical structure, and when the difference is 0, that is, in the case of a racemic mixture, the helical structure does not occur. There may be differences in the refractive index in the three-dimensional direction after the orientation is fixed, depending on the presence or absence of a helical structure and the degree of the helical pitch.The optical purity of the structural unit having an asymmetric carbon atom depends on the refractive index in the three-dimensional direction. Can be one effective means of controlling.

The structural unit ((C) unit) represented by the general formula —O—Z—O controls the transition temperature, the liquid crystal temperature range, the viscosity, etc. when the polyester used in the present invention forms a liquid crystal phase. Therefore, it is an important component, and the type and content can be selected according to the physical properties of the intended polymer. The number of carbon atoms contained in the Z group is 3 to 12,
In addition, it is necessary that the number of carbon atoms in the part constituting the main chain is odd. The proportion of the (C) unit is preferably 0 to 59 mol%, particularly preferably 5 to 50 mol%. Theoretically, it is preferable that the total amount of the (B) unit and the (C) unit be a molar ratio approximately equal to the (A) unit. The (C) unit is derived from the corresponding diol or its derivative (for example, a diacetoxy derivative). Representative examples of Z, the general - _(CH 2) - _n (where n is 3 to 11, preferably an odd number of 3-9) alkylene group represented by a part of the hydrogen atoms of the alkylene group having a carbon Those substituted with an alkyl group of the number 1 to 4 (however, the total number of carbon atoms does not exceed 12) and the like can be mentioned. In particular,

[0022]

[Chemical 13]

The method for producing the liquid crystalline polyester of the present invention is not particularly limited, and a known method for producing a general polyester is a melt polymerization method or an acid using a corresponding dicarboxylic acid dichloride (ClOC-X-COCl). It can be synthesized by the chloride method. In the case of melt polycondensation,
It can be prepared by polymerizing the corresponding dialkyl ester of a dicarboxylic acid (eg MeOOC-X-COOMe), the corresponding optically active diol (HO-Y-OH) and another diol (HO-Z-OH) at elevated temperature. . The molecular weight can be easily adjusted by controlling the charging composition, the polymerization time and the like. In order to accelerate the polymerization reaction, an alkali metal salt which is a known polyester polymerization catalyst, Fe, Mn, Cd, Mg, Ba, Ti, Zn,
Metal salts such as Pb, Co, Sb and Sn may be used alone or in combination. A phosphorus compound may be added as a decomposition inhibitor.

If the acid chloride method is used, polymerization can be carried out under milder conditions. For example, a predetermined amount of a corresponding acid chloride (ClOC-X-COCl), a corresponding optically active diol (HO-Y-OH) and another diol (HO-Z-OH) are dissolved in a solvent and pyridine or the like is added. The desired polymer can be easily obtained by heating in the presence of an acid acceptor.

The molecular weight of the liquid crystalline polyester of the present invention is phenol / tetrachloroethane (60/40 weight ratio).
Logarithmic viscosity of 0.01 to 5.0d measured at 30 ° C in medium
It is preferably in the range of 1 / g, particularly preferably in the range of 0.05 to 3.0 dl / g. If the logarithmic viscosity is less than 0.01 dl / g, the strength after immobilization tends to be weak, and if it exceeds 5.0 dl / g, the viscosity of the liquid crystal state may be too high to obtain sufficient orientation.

The compensating plate of the present invention has a structure in which the refractive index in the thickness direction is uniform and monodomain is larger than the refractive index in at least one in-plane direction, and its alignment state can be easily fixed. It is manufactured by heat-treating polyester on a self-supporting substrate or a vertical alignment film and fixing it without impairing the alignment in the liquid crystal state.
Homeotropic alignment is a typical example of the alignment behavior having a three-dimensional refractive index distribution required for the compensator of the present invention. The homeotropic orientation referred to here includes not only the structure in which the major axis of the molecule is oriented perpendicular to the substrate, but also the structure tilted at an angle (for example, 45 ° or less) from the normal direction of the substrate (that is, pretilted). is there. It is essential that the liquid crystalline polyester that can stably maintain the alignment in the liquid crystal state even near room temperature has the following properties. From the viewpoint of liquid crystal phase series, it is important that the liquid crystal phase does not have a crystal phase at a lower temperature portion. If a crystalline phase exists, it will inevitably pass through this phase during cooling for immobilization, and as a result the orientation once obtained will be destroyed, resulting in an unsatisfactory transparency and viewing angle compensation effect. Become. Therefore, in order to manufacture the compensator of the present invention, it is essential to use a liquid crystalline polyester having a glass phase at a temperature lower than the liquid crystal phase. The liquid crystal phase of the liquid crystalline polyester is not particularly limited, but usually a smectic phase or the like can be mentioned.

A typical constitutional example of the compensating plate of the present invention has a two-layer structure of a transparent substrate and a liquid crystalline polyester film formed on the substrate. Examples of the type of translucent substrate used include glass, translucent plastic film, plastic sheet, polarizing film and the like. As the glass, soda glass, silica-coated soda glass, borosilicate glass, or the like is used. The plastic substrate is preferably optically isotropic, and for example, polymethyl methacrylate, polystyrene, polycarbonate, polyether sulfone, polyphenylene sulfide, amorphous polyolefin, triacetyl cellulose or epoxy resin can be used. Among them, polymethyl methacrylate, polycarbonate, polyether sulfone, amorphous polyolefin, triacetyl cellulose and the like are preferably used. Alternatively, a translucent substrate that has been subjected to an alignment treatment can be used as the substrate.
For example, a substrate having a vertical aligning agent layer such as a silanizing agent, lecithin, or a chromium complex, or a substrate having an alignment film known in the art such as a rubbing-treated polyimide film or a silicon oxide oblique vapor deposition film can be used. The viewing angle compensator is manufactured by forming a film of the liquid crystalline polyester on the transparent substrate that has not been subjected to the alignment treatment or on the transparent substrate that has been subjected to the alignment treatment.

The liquid crystalline polyester is applied on the substrate in a solution state or a molten state. The polymer solution is obtained by dissolving a polymer having a predetermined concentration in a predetermined solvent. In the case of using a composition composed of two or more kinds of polymers, taking the case of solution mixing as an example, first, each component is dissolved in a solvent at a predetermined ratio to prepare a solution having a predetermined concentration.
The solvent to be used varies depending on the type of polymer, but it is usually acetone, methyl ethyl ketone, ketones such as cyclohexanone, ethers such as tetrahydrofuran and dioxane, halogenated hydrocarbons such as chloroform, dichloroethane, tetrachloroethane, trichloroethylene, tetrachloroethylene, orthodichlorobenzene. A mixed solvent of these and phenol, dimethylformamide, dimethylacetamide, dimethylsulfoxide, N-methylpyrrolidone and the like can be used.
The concentration of the solution varies greatly depending on the viscosity of the polymer,
Usually, it is used in the range of 5 to 50%, preferably in the range of 8 to 30%. Next, this solution is applied onto a light-transmissive glass plate not subjected to orientation treatment, a plastic plate, a light-transmissive substrate such as a plastic film, or a light-transmissive substrate subjected to orientation treatment. As a method for applying the polymer solution, a spin coating method, a roll coating method, a printing method, a curtain coating method, a dipping and pulling method and the like can be adopted. After coating, the solvent is removed by drying, and heat treatment is performed at a predetermined temperature for a predetermined time to complete a monodomain liquid crystal alignment. The heat treatment temperature is preferably a high temperature at which the viscosity of the polymer can be lowered. However, since the liquid crystal phase generally has an isotropic phase in a higher temperature portion, orientation cannot be obtained even by heat treatment in this temperature range. As described above, according to the characteristics of the polymer, it is preferable to perform the heat treatment at a temperature not lower than the glass transition point and not higher than the transition point to the isotropic phase. Generally, the temperature is preferably in the range of 40 ° C to 300 ° C, and particularly preferably 50 ° C. The range from 0 ° C to 250 ° C is preferred. The time required to obtain sufficient orientation by heat treatment varies depending on the composition and molecular weight of the polymer, but cannot be generally stated.
A range of 5 seconds to 120 minutes is preferable, and particularly 10 seconds to 6 minutes.
The range of 0 minutes is preferred. If it is shorter than 5 seconds, the orientation becomes insufficient, and if it is longer than 120 minutes, the transparency of the obtained compensator may be lowered. A similar orientation state can be obtained by applying a polymer in a molten state to a substrate or an orientation-treated substrate and then heat-treating it. By performing these treatments using the liquid crystalline polyester, a structure having a refractive index in the thickness direction larger than that in at least one in-plane direction can be obtained in the liquid crystal state.

By subsequently cooling the orientation state thus obtained, the orientation can be fixed without impairing the orientation.
Generally, when a polymer having a crystal phase at a temperature lower than the liquid crystal phase is used, the alignment in the liquid crystal state is broken by cooling. According to the method of the present invention, since a polymer system having a glass phase at a temperature showing a liquid crystal phase is used, such a phenomenon does not occur, and the refractive index in the thickness direction is completely in at least one direction in the plane. A structure having a refractive index larger than that of can be fixed.

The cooling rate is not particularly limited, and may be slow cooling or forced cooling such as air cooling or water cooling in order to improve productivity efficiency. The film thickness after immobilization is 0.1 μm
To 50 μm is preferable, and a range from 0.5 μm to 40 μm is particularly preferable.

In order for the viewing angle compensating plate of the present invention to exert a sufficient viewing angle compensating effect, the refractive index in the three-dimensional direction of the layer (compensation layer) made of a polymer liquid crystal film should be matched according to the liquid crystal display cell. is necessary. The control of the refractive index in the three-dimensional direction in the compensation layer can be achieved by the kind of polymer or the mixture of two or more kinds of polymers. However, in any case, it is important that the refractive index in the thickness direction is higher than the refractive index in at least one direction in the plane. The difference between the refractive index in the thickness direction and the refractive index in at least one direction in a plane smaller than the refractive index is usually 0.01 or more, preferably 0.
It is more than 05. At this time, it is necessary to control the thickness of the compensation layer as well, but it is not so strict and it is preferable that the thickness can be reproduced within an error range of ± 10%, more preferably ± 5%. With such an error, the visual angle compensation effect does not look different.

The viewing angle compensator thus obtained may be used as it is, or may be provided with a transparent plastic protective layer for surface protection. Further, it may be used in a form integrated with other optical elements such as a polarizing plate.

The polymer liquid crystal film thus obtained has a viewing angle compensating effect for a liquid crystal display having a twist angle in the range of 70 to 300 degrees. For example, the viewing angle dependence of a TN display or STN display can be improved. The position where the viewing angle compensating plate of the present invention is installed is not particularly limited as long as it is between the upper and lower polarizing plates of the liquid crystal display, and may be, for example, between the lower polarizing plate and the liquid crystal display cell or the liquid crystal display cell. It may be between the upper polarizing plates. Further, for example, when a color compensating plate is used above the liquid crystal display cell, the viewing angle compensating plate is provided either between the lower polarizing plate and the liquid crystal display cell, between the liquid crystal display cell and the color compensating plate, or between the color compensating plate and the upper polarizing plate. A good viewing angle compensation effect can be obtained even when the is installed. Further, the viewing angle compensator of the present invention can exert the same effect in a liquid crystal display in which a color filter for color display is installed.

As described above, the viewing angle compensator for a liquid crystal display manufactured according to the present invention not only contributes to high performance of the liquid crystal display by reducing the viewing angle dependence peculiar to the liquid crystal display, but also the liquid crystal display. It is considered to be able to contribute to the enlargement of the display area and is of great industrial value.

[0035]

EXAMPLES Examples will be described below, but the present invention is not limited thereto. The analytical methods used in the examples are as follows.

(1) Determination of Polymer Composition The polymer was dissolved in deuterated chloroform or deuterated trifluoroacetic acid and measured by ^1- NMR (400 nm) (JNM-GX400 manufactured by JEOL Ltd.).

(2) Measurement of logarithmic viscosity Using an Ubbelohde viscometer, the viscosity was measured at 30 ° C. in a mixed solvent of phenol / tetrachloroethane (60/40 weight ratio).

(3) Determination of liquid crystal phase sequence DSC (DuPont 990 Thermal An)
It was determined by the measurement of the alizer) and observation with an optical microscope (BH2 polarizing microscope manufactured by Olympus Optical Co., Ltd.).

(4) Measurement of three-dimensional structure of polymer liquid crystal film after orientation and fixation The three-dimensional refractive index was measured with an Abbe refractometer (Type-4 manufactured by Atago Co., Ltd.). The structure was determined by conoscopic observation with an optical microscope.

Example 1. 4,4'-biphenyldicarboxylic acid diethyl ester 1
00 mM, (R) -1,3-butanediol 50 mM and 1,5-pentanediol 50 mM were used at 180 ° C. for 2 hours and 200 ° C. for 1 hour while stirring in a nitrogen stream.
Melt polycondensation was performed while gradually increasing the temperature at 220 ° C. for 1 hour and at 240 ° C. for 1 hour. Finally, the system was depressurized and reacted at 250 ° C. for 15 minutes to synthesize a polymer. Next, the obtained polymer was dissolved in tetrachloroethane and reprecipitated with methanol to obtain a purified polymer 27.
0 g was obtained. This polymer had a logarithmic viscosity of 0.12, had only a chiral smectic C phase as a liquid crystal phase, and had a glass transition point of 20 ° C.

[0041]

[Chemical 14]

A 15 wt% tetrachloroethane solution was prepared using this polyester. With this solution, 1
On the borosilicate glass plate having a size of 0 cm × 10 cm and a thickness of 1.1 mm, the polymer solution was applied by the screen printing method, dried, and heat-treated at 140 ° C. × 10 minutes and then cooled to obtain the thickness of the compensation layer. A viewing angle compensator of 3.5 μm was manufactured. The obtained compensator was completely transparent, and it was found by conoscopic observation that it had a homeotropically oriented positive crystal structure.

Example 2. The polymer solution of Example 1 was added to a high refractive glass plate (Hoya
Manufactured, cast on a refractive index of 1.84), dried and heat-treated in the same manner as in Example 1. The obtained transparent film having a thickness of 3.0 μm had the same refractive index of 1.57 in all directions parallel to the substrate and 1.74 in the thickness direction.

Example 3. The polymer solution of Example 1 was applied to a high refractive index glass substrate having a rubbed polyimide film, dried, and 140 ° C.
When heat-treated for 10 minutes, a transparent film having a thickness of 3.4 μm was obtained. Observation with a conoscope revealed that it has a homeotropically oriented positive crystal structure.
The refractive index was 1.57 in all directions parallel to the substrate and was 1.74 in the thickness direction.

Example 4. In the STN display color-compensated by the two-layer cell system, the viewing angle compensator of Example 1 is arranged so that the compensating layer faces upward.
It was arranged like. As a result of investigating the compensation effect of this test display, as shown in FIG. 2, the decrease in contrast with the increase of the viewing angle becomes slower than when the viewing angle compensator is not used.

Example 5. When the viewing angle compensator of Example 1 was placed on the TN cell on the TN display and the viewing angle dependency was compared with that when no viewing angle compensator was used, the measurement results of FIG. 3 were obtained.

Example 6. 4,4'-biphenyldicarboxylic acid diethyl ester 1
00 mM, racemic 1,3-butanediol 50 mM
Polymer synthesis, purification, and solution preparation were performed in the same manner as in Example 1, using 1,5-pentanediol and 50 mM. This polymer has a logarithmic viscosity of 0.13, the only liquid crystal phase that has a smectic C phase, and a glass transition point of 21 ° C.
Met.

[0048]

[Chemical 15]

This polymer solution was applied to a high refractive index glass substrate having a rubbed polyimide film and dried.
When heat-treated at 0 ° C. for 10 minutes, a transparent film having a thickness of 3.4 μm was obtained. When the conoscope was observed, no isogyre was observed. The refractive index was 1.60 in the direction parallel to the rubbing direction, 1.54 in the direction perpendicular thereto, and 1.74 in the thickness direction.

Example 7. The polymer of Example 1 and the polymer of Example 6 were 75: 2.
The mixture was mixed at a weight ratio of 5, 50:50 and 25:75 to obtain a 15 wt% tetrachloroethane solution. Each solution is applied to a glass substrate by spin coating, and then 1
A heat treatment was performed for 20 minutes while drying the solution at 30 ° C. The thickness of the obtained polymer film was about 4 μm, and it was found by conoscopic observation that each film had a homeotropically oriented positive crystal structure.

Example 8. 4,4'-biphenyldicarboxylic acid diethyl ester 1
The polymer was synthesized, purified, and solution-purified in the same manner as in Example 1 by using (R) -2-chlorobutanediol 40 mM and optical purity 5% (R) -2-chlorobutanediol 40 mM and 2-methylnonanediol 60 mM, and the polymer represented by the following formula ( Logarithmic viscosity 0.2
1, Tg = 30 ° C.) was synthesized. 230 this polymer
It was melted at 0 ° C. and applied to a substrate heated to 200 ° C. on a hot plate. Then, the temperature of the hot plate was lowered to 130 ° C., the coated surface was covered with a plain glass plate, and the glass plate covered with the above was slightly shifted right and left several times to give a shear to the polymer. After standing at this temperature for 15 minutes, the sample was removed from the hot plate and air-cooled to obtain a transparent liquid crystal film sandwiched between two pieces of glass. When this film was subjected to conoscopic observation, no isogyre was observed. The same operation was performed using a high-refractive index glass substrate, and when the refractive index was measured, it was 1.59 in the direction parallel to the shearing direction, 1.55 in the direction perpendicular thereto, and 1.72 in the thickness direction. there were.

[0052]

[Chemical 16]

Example 9. The glass plate washed with concentrated sulfuric acid was dipped in a toluene solution of octadecyltriethoxysilane to form a vertical alignment film on the glass plate. The polymer of the formula below was dissolved in a mixed solvent of tetrachloroethane / phenol (weight ratio 4/6) to make the total polymer concentration 28 wt%, and the substrate was dipped in this polymer solution, pulled up and applied, and then left at room temperature for 5 hours, and then, It was dried at 100 ° C. for 2 hours and heat-treated at 180 ° C. for 30 minutes. It was found that a transparent film of about 8 μm was obtained and had a homeotropically oriented positive crystal structure.

[0054]

[Chemical 17]

Example 10. An 8 wt% trichloroethylene solution of the polymer of the following formula (logarithmic viscosity 0.10) was applied on a polyethylene terephthalate film having a thickness of 50 μm with a roll coater, and 6
It was dried at 0 ° C. for 20 seconds, then heat-treated at 200 ° C. for 20 seconds and cooled and fixed with cold air to prepare a compensating plate having a compensating layer thickness of 3.2 μm. Conoscopic observation of the obtained compensation layer revealed that it had a homeotropically oriented positive crystal structure.

[0056]

[Chemical 18]

[0057]

The viewing angle compensator of the present invention comprises a liquid crystalline polyester film having a fixed structure in which the refractive index in the thickness direction is greater than the refractive index in at least one direction in the plane, which is one of the major problems of liquid crystal displays. It is possible to greatly improve the viewing angle dependency. As a result, it exerts great power for high-quality display and high performance of liquid crystal displays, and its industrial value is extremely large.

[Brief description of drawings]

FIG. 1 is a two-layer cell color compensation type S used in Example 4 of the present invention.
It is sectional drawing which shows the structure of a TN display and a viewing-angle compensation plate.

FIG. 2 shows the results obtained in Example 4, showing the relationship between the viewing angle and the contrast when the STN test display is viewed from above, below, left and right.

FIG. 3 is a result obtained in Example 5 and shows the relationship between the viewing angle and the contrast when the TN test display is viewed from above, below, left, and right.

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] August 30, 1991

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0033

[Correction method] Change

[Correction content]

The polymer liquid crystal film thus obtained has a viewing angle compensating effect for a liquid crystal display having a twist angle in the range of 70 to 300 degrees. For example, the viewing angle dependence of a TN display or STN display can be improved. The position where the viewing angle compensating plate of the present invention is installed is not particularly limited as long as it is between the upper and lower polarizing plates of the liquid crystal display, and may be, for example, between the lower polarizing plate and the liquid crystal display cell or the liquid crystal display cell. It may be between the upper polarizing plates. Further, for example, when a color compensating plate is used above the liquid crystal display cell, the viewing angle compensating plate is provided either between the lower polarizing plate and the liquid crystal display cell, between the liquid crystal display cell and the color compensating plate, or between the color compensating plate and the upper polarizing plate. A good viewing angle compensation effect can be obtained even when the is installed. Well
Also, one compensator may be used or two or more compensators may be used.
You may arrange | position between polarizing plates. Further, the viewing angle compensator of the present invention can exert the same effect in a liquid crystal display in which a color filter for color display is installed.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0056

[Correction method] Change

[Correction content]

[0056]

[Chemical 18] Example 11 10 wt% Tet of polymer of the following formula (logarithmic viscosity 0.12)
Prepare a solution of lachloroethane and prepare a large 10 cm x 10 cm
By spin coating on a glass substrate with a thickness of 1.1 mm
After coating, drying, heat treatment at 140 ° C for 30 minutes, cooling,
A transparent compensation layer having a thickness of 1.0 μm was obtained. Conos this layer
As a result of observing the scope
It is confirmed that it has positive crystallinity by inserting a sensitive color inspection plate.
I confirmed. Another compensator with almost the same thickness as this
However, two viewing angle compensators are used for the STN display having color compensation cells.
It was incorporated into the spray in the configuration of FIG. As a result,
A good viewing angle compensation effect as shown was obtained.

[Chemical 19] Example 12 Using the polymer solution used in Example 11, two viewing angle compensators were prepared in the same process as in Example 11 except that the spin coating rotation speed was changed. Both compensating layers have a thickness of 0.6 μm
Met. These compensators were incorporated into the TN display in the configuration of FIG. As a result, the change in display color tone depending on the viewing angle was reduced, and the viewing angle compensation effect was confirmed.

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

FIG. 1 is a two-layer cell color compensation type S used in Example 4 of the present invention.
It is sectional drawing which shows the structure of a TN display and a viewing-angle compensation plate.

FIG. 2 shows the results obtained in Example 4, showing the relationship between the viewing angle and the contrast when the STN test display is viewed from above, below, left and right.

FIG. 3 shows the results obtained in Example 5, showing the relationship between the viewing angle and the contrast when the TN test display is viewed from above, below, left and right.

FIG. 4 is a two-layer cell color compensation type used in Example 11 of the present invention .
FIG. 3 is a cross-sectional view showing the structure of an STN display and a viewing angle compensation plate.
is there.

FIG. 5 : STN test with the results obtained in Example 11 .
The viewing angle and control when the display is viewed from the top, bottom, left, and right
It represents the last relationship.

FIG. 6 is a cross-sectional view showing the configurations of a TN display and a viewing angle compensation plate used in Example 12 of the present invention.

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Claims (3)

[Claims] 1. A transparent substrate, and a structure formed on the substrate, in which a refractive index in a thickness direction in a liquid crystal state is higher than a refractive index in at least one in-plane direction, and a temperature below a liquid crystal transition point. Then, a viewing angle compensating plate for a liquid crystal display device, which is composed of a film made of a liquid crystalline polyester consisting of structural units (A) and (B) represented by the following general formula, which are in a glass state, and optionally (C). [Chemical 1] [Chemical 2] Which represents one or more structural units selected from the group consisting of: (B) —O—Y—O— 1 to 60 mol% [wherein Y contains at least one asymmetric carbon atom and has 3 to 12 carbon atoms] Shows a certain divalent aliphatic group] (C) -O-Z-O-0 to 59 mol% [wherein Z has 3 to 12 carbon atoms and the carbon number of the portion constituting the main chain of the polymer is Shows an odd-numbered linear or branched divalent aliphatic group] 2. The viewing angle compensator for a liquid crystal display device according to claim 1, wherein the liquid crystalline polyester is homeotropically aligned in a liquid crystal state. 3. A structural unit (A) represented by the following general formula,
A liquid crystalline polyester comprising (B) and optionally (C) is heat-treated on a substrate at a temperature not lower than the glass transition point of the liquid crystalline polymer and then cooled to a temperature not higher than the glass transition point of the liquid crystalline polymer. A viewing angle compensator for a liquid crystal display element, which comprises a film having a fixed structure in which the refractive index in the thickness direction is higher than the refractive index in at least one direction in the plane. [Chemical 3] [Chemical 4] Which represents one or more structural units selected from the group consisting of: (B) —O—Y—O— 1 to 60 mol% [wherein Y contains at least one asymmetric carbon atom and has 3 to 12 carbon atoms] Shows a certain divalent aliphatic group] (C) -O-Z-O-0 to 59 mol% [wherein Z has 3 to 12 carbon atoms and the carbon number of the portion constituting the main chain of the polymer is Shows an odd-numbered linear or branched divalent aliphatic group]