JPH093454A - Polymer composition and production and liquid crystal display element using the same - Google Patents

Abstract

PURPOSE: To produce a polymer composition, containing a functional group, polymerizable and cross-linkable with light and heat in one of a homeotropic oriented liquid crystal polymer and a homogeneous oriented liquid crystal polymer and providing a highly durable liquid crystal display element by using an optical thin film excellent in heat and solvent resistances. CONSTITUTION: This polymer composition contains a functional group, polymerizable and cross-linkable with light and heat in one of a homeotropic oriented liquid crystal polymer comprising a dicarboxylic acid unit of formula I [X is H, a halogen, a 1-4C alkyl, etc.; (k0) is 0-2], etc., and a diol unit, etc., of formula II, etc., such as a polyester and a homogeneous oriented liquid crystal polymer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polymer composition that can be used for optical elements, a manufacturing method using the same, and a liquid crystal display element.

[0002]

2. Description of the Related Art Liquid crystalline polymers exhibit various liquid crystal phases based on their original alignment structure, and these liquid crystal structures can be fixed. Therefore, optical recording, nonlinear optical materials, liquid crystal alignment films, optical fibers, liquid crystal displays. Active researches have been made in various functional material fields such as optical elements for optical elements. Since liquid crystalline polymers exhibit various orientations, materials obtained by fixing these molecular orientations exhibit various properties in terms of optical properties such as refractive index and birefringence, and Since it becomes possible to control the polarization state and the like, it can be applied in a wide range as an optical material.

A typical example of the orientation of the liquid crystalline polymer is nematic orientation or twisted nematic orientation. When these are oriented on a substrate, in the nematic orientation liquid crystal, the orientation direction of the liquid crystalline molecules ( In the following, a homogeneous alignment in which the director is substantially parallel to the substrate or a homeotropic alignment in which the director is substantially vertical is obtained. Further, in the chiral nematic alignment liquid crystal, an alignment having a helical structure while being homogeneously aligned is obtained.

Further, as disclosed in JP-A-6-347742, by mixing a homeotropic alignment liquid crystalline polymer and a homogeneous alignment liquid crystalline polymer, the liquid crystal molecules are tilted from the plane of the substrate. A tilt orientation is obtained. As described above, recently, many attempts have been made to develop a function that cannot be achieved by a liquid crystal polymer alone by mixing it with another liquid crystal polymer or another organic compound or inorganic compound.

At the same time, these useful polymer compositions have come to be used outdoors and under severe environmental conditions, and are required to have higher durability than ever before. In such an environment, in the case of a liquid crystalline polymer composition in which the above liquid crystalline polymer is a mixture, the glass transition temperature or lower due to precipitation / separation of the mixture or phase separation between the liquid crystalline polymers. However, there is a problem that the stable orientation fixation of (1) cannot always be maintained.

[0006]

Therefore, an object of the present invention is to provide an optically highly functional and highly durable liquid crystalline compound comprising at least a homeotropically aligned liquid crystalline polymer and a homogeneously aligned liquid crystalline polymer. It is intended to provide a polymer composition and a liquid crystal display device using such a highly durable polymer composition.

[0007]

Means for Solving the Problems As a result of intensive studies by the present inventors, [1] a liquid crystalline polymer composition containing at least a homeotropically aligned liquid crystalline polymer or a homogeneously aligned liquid crystalline polymer And one of them has a functional group capable of being polymerized or crosslinked by light or heat, [2]
[3] A liquid crystalline polymer composition characterized by comprising a homeotropically aligned liquid crystalline polymer and a homogeneously aligned liquid crystalline polymer together with at least one kind of a substance capable of being polymerized or crosslinked by light or heat, [3] By providing a method for producing a thin film, which comprises forming a thin film of the liquid crystalline polymer composition according to [1] or [2] and then polymerizing or crosslinking the composition by light or heat,
[4] To provide a method for producing a thin film in which a thin film made of a polymer composition containing a polyester-based liquid crystalline polymer composition is formed, and then the film is cured by polymerization or crosslinking by light or heat. [5] A liquid crystal display element comprising a liquid crystal cell and a polarizing plate, wherein the thin film obtained by the production method according to [3] or [4] is used as an optically anisotropic element. Have found that the present invention is achieved.

The present invention will be described in detail below. The liquid crystalline polymer composition of the present invention is a functional group capable of being polymerized or crosslinked by at least one of a liquid crystalline polymer having at least homeotropic alignment and a liquid crystalline polymer having homogeneous alignment or another compound. The major feature is that it contains as an essential component.

First, a homeotropic alignment liquid crystalline polymer (polymer) and a homogeneous alignment liquid crystalline polymer (polymer), which are important constituents of the polymer composition of the present invention.
The features of will be described. Homeotropic alignment refers to an alignment state in which the director is substantially perpendicular to the plane of the substrate, and homogeneous alignment refers to an alignment state in which the director is substantially parallel to the plane of the director substrate.

The orientation of the polymer can be determined by determining whether the liquid crystalline polymer has a homeotropic orientation or a homogeneous orientation in a liquid crystal state when a liquid crystalline polymer layer is formed on a substrate. The substrate that can be used for this determination is not particularly limited, but examples include a glass substrate (such as soda glass, potash glass, borosilicate glass or crown glass, and optical glass such as flint glass), at the liquid crystal temperature of the liquid crystalline polymer. Heat-resistant plastic film or sheet such as polyethylene terephthalate, polyethylene naphthalate, polyphenylene oxide, polyimide, polyamide imide, polyether imide, polyamide, polyether ketone, polyether ether ketone, polyketone sulfide, polyether sulfone You can

These substrates are used after cleaning their surfaces with acids, alcohols, detergents, etc., but they are used without any surface treatment such as silicon treatment. When a polymer film is formed on these appropriate substrates and heat-treated at a liquid crystal temperature, at least one of these exemplified substrates is homeotropically aligned on at least one of the substrates and is referred to as a homeotropic alignment polymer. Let's define it. On the other hand, a polymer having a homogeneous orientation with respect to any of the substrates, that is, a polymer which is determined not to have homeotropic orientation is defined as a homogeneous orientation polymer. However, depending on the polymer, there is a polymer that specifically homeotropically aligns at a temperature in the vicinity of the liquid crystal layer-isotropic phase transition point. It is performed at a temperature of ℃ or less.

Next, the structure of the polymer will be described.
First, the features common to homeotropically oriented polymers and homogeneously oriented polymers will be described. The type of liquid crystalline polymer used is not particularly limited, polyester,
Main chain type liquid crystal polymer such as polyamide, polycarbonate, polyester imide, or polyacrylate,
Examples thereof include side chain type liquid crystal polymers such as polymethacrylate, polymalonate and polysiloxane.

Of these, polyester is preferred from the viewpoints of ease of synthesis, orientation, glass transition point and the like. The constitutional unit of the polyester is not particularly limited, but preferable examples include (a) a unit derived from a dicarboxylic acid (hereinafter referred to as a dicarboxylic acid unit) and (b) a unit derived from a diol ( Hereinafter, examples include diol units), (c) units derived from oxycarboxylic acids having a carboxyl group and a hydroxyl group in one unit (hereinafter referred to as oxycarboxylic acid units), and the like. A unit derived from a compound having an asymmetric carbon (optically active substance or racemic body) can also be used as a constitutional unit, and most polymers containing an optically active unit are used as a liquid crystal phase in a chiral nematic phase (twisted nematic phase). , Cholesteric phase). On the other hand, those containing no optically active unit show a nematic phase as a liquid crystal phase.
The structure of polyester is (a) + (b) type,
There are (a) + (b) + (c) type and (c) single type.

Examples of the dicarboxylic acid unit (a) include, for example:

[0015]

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(X is hydrogen, halogen such as chlorine or bromine, an alkyl group having 1 to 4 carbon atoms (eg, methyl group, ethyl group, propyl group, isopropyl group, butyl group, t-butyl group, etc.)) Or an alkoxy group (for example,
Methoxy group, ethoxy group, propoxy group, butoxy group and the like) or phenyl group. k0 is 0, 1
Or 2 and so on),

[0017]

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[0018]

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[0019]

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And the like. (* Indicates optically active carbon, the same applies below)

Examples of the diol unit (b) include, for example:

[0022]

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[0023]

[Chemical 6]

And the like.

As the oxycarboxylic acid unit of (c),
For example

[0026]

[Chemical 7]

And the like.

Representative examples of homeotropically oriented polymers and homogeneously oriented polymers are shown below.

The homeotropically oriented polymer and the other homogeneously oriented polymer are distinguished by the judgment method described above. As the polymer having the homeotropic orientation, the above-mentioned polyester-based polymer is typically used. As the above structural unit or additional structural unit, a polyester containing an aromatic unit having an alkyl group having 3 or more carbon atoms, preferably 3 to 12 carbon atoms as a substituent or a part of the substituent, or fluorine or fluorine as such a structural unit. Examples include polyesters containing an aromatic unit having a fluorine substituent as a substituent or a part of the substituent.

Among such constitutional units, examples of the aromatic unit having a substituent or an alkyl group having 3 or more carbon atoms as a part of the substituent include, for example,

[0031]

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(R is an alkyl group having 3 to 12 carbon atoms) and the like. Further, as the aromatic unit having fluorine or a fluorine substituent,

[0033]

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And the like.

Further, in order to fix the alignment structure of the liquid crystalline polymer composition of the present invention, it is preferable to use one which takes a glass state without crystallization at a temperature lower than the liquid crystal phase. When the liquid crystal structure of the composition is fixed, the polymer molecules are first aligned at the liquid crystal temperature, and then polymerization for fixing is performed, but in the case of a composition having crystallinity in a portion not involved in the polymerization, it is obtained once. The oriented state may be destroyed. For example, in the case of the above-illustrated polyester-based polymer, an ortho-substituted aromatic unit is preferably used as a constituent unit that suppresses crystallization, and a polyester-based polymer containing such a unit is suitable.

The ortho-substituted aromatic unit as used herein means a structural unit in which the bonds forming the main chain are in ortho positions with respect to each other. In order for the composition to take the glass state without causing crystallization at a temperature lower than the liquid crystal phase, at least one of the homeotropically oriented polymer and the homogeneously oriented polymer forming the composition contains these structural units. Preferably. Specific examples of these ortho-substituted aromatic units include the following catechol units, salicylic acid units, phthalic acid units, and those having a substituent on the benzene ring of these groups. For example,

[0037]

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There are others. Among these, particularly preferable examples include the following.

[0039]

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[0040]

[Chemical 12]

With respect to the homeotropic alignment polymer and the homogeneous alignment polymer which compose the liquid crystal composition of the present invention, the following polymers can be specifically exemplified as suitable polyesters.

First, as the homeotropically oriented polymer,

[0043]

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A polymer constituted by the structural unit of (wherein k, l, and m are merely composition ratios (mole), and k = 1 + m, 1 / m = 100/0 to 20/80, preferably Is 95/5 to 30/70)

[0045]

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A polymer composed of the structural unit (wherein k, l, and m are merely composition ratios (mole), and k = l + m, l / m = 98/2 to 20/80, preferably Is 95/5 to 30/70)

[0047]

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A polymer composed of the structural unit of (wherein k, l, m, and n are merely composition ratios (mole), and k = l + m + n, 1 / m = 98/2 to 20/8.
0, preferably 95/5 to 30/70, 1 / n = 98 /
2 to 20/80, preferably 95/5 to 30/70)

[0049]

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A polymer composed of the structural unit of (wherein k, l, and m are merely compositional ratios (mole), and k = l + m, k / l = 98/2 to 20/80, preferably Is 95/5 to 30/70)

[0051]

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A polymer composed of the structural unit of (wherein k, l, m, and n are merely composition ratios (mole), and k = l + m + n, k / l = 98/2 to 20/8.
0, preferably 95/5 to 30/70, 1 / m = 98 /
2 to 20/80, preferably 95/5 to 30/70, and n is an integer of 2 to 12)

[0053]

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A polymer composed of the structural unit of (wherein k, l, and m are merely composition ratios (mole), and k = l + m, 1 / m = 98/2 to 20/80, preferably Is 95/5 to 30/70)

[0055]

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A polymer composed of the structural unit of (wherein k, l, m and n simply represent composition ratios (mole), and k + l = m + n, k / l = 100/0 to 0/1.
00, preferably 95/5 to 5/95, m / n = 98 /
2 to 20/80, preferably 95/5 to 30/70)

[0057]

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Polymer composed of the structural unit (wherein k, l, and m are merely composition ratios (mole), and k = l + m, 1 / m = 100/0 to 0/100, preferably Is 98/2 to 2/98, and n is an integer of 2 to 12)

And the like. Of course, in these formulas, the composition ratios of the respective structural units k, l, m, etc. merely indicate a molar ratio, not a block-like unit.

Examples of the homogeneously oriented polymer include, for example,

[0061]

[Chemical 21]

A polymer composed of the structural unit (wherein k, l, and m are simply composition ratios (mole), and k = 1 + m, 1 / m = 80/20 to 20/80, preferably Is 75/25 to 25/75)

[0063]

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A polymer composed of the structural unit of (wherein k, l, and m are merely compositional ratios (mole), and k = 1 + m, 1 / m = 80/20 to 20/80, preferably Is 75/25 to 25/75)

[0065]

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A polymer composed of the structural unit of (wherein k, l, and m are merely composition ratios (mole), and k = l + m, 1 / m = 80/20 to 20/80, preferably Is 75/25 to 25/75)

[0067]

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A polymer composed of the structural unit of (wherein k, l, m, and n are merely composition ratios (mole), and k = l + m + n, 1 / m = 80/20 to 20 /
80, preferably 75/25 to 25/75, 1 / n = 8
0/20 to 20/80, preferably 75/25 to 25 /
75)

[0069]

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A polymer composed of the structural unit of (wherein k, l, m, and n are merely composition ratios (mole), and k + l = m + n, k / l = 80/20 to 20 /
80, preferably 75/25 to 25/75, m / n = 8
0/20 to 20/80, preferably 75/25 to 25 /
75)

[0071]

[Chemical formula 26]

A polymer composed of the structural unit (wherein k, l, and m are simply composition ratios (mole), and k = l + m, 1 / m = 80/20 to 20/80, preferably Is 75/25 to 25/75)

[0073]

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A polymer composed of the structural unit (wherein k, l, and m are merely composition ratios (mole), and k / l = 80/20 to 20/80, preferably 75.
/ 25 to 25/75, and 1 / m = 80/20 to 20
/ 80, preferably 75/25 to 25/75)

[0075]

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A polymer constituted by the structural unit of (wherein, k, l, m and n simply indicate the composition ratio (mol), and k + l = m + n, k / l = 80/20 to 20 /
80, preferably 75/25 to 25/75, m / n = 8
0/20 to 20/80, preferably 75/25 to 25 /
75 and p is 2 to 12)

[0077]

[Chemical 29]

A polymer composed of the structural unit (wherein k, l, and m are simply composition ratios (mole), and k + 1 = m, k / l = 80/20 to 20/80, preferably Is 75/25 to 25/75, and p is 2 to 12
Is)

And the like.

The molecular weight of these polymers can be determined in various solvents such as phenol / tetrachloroethane (60/4
0 (weight ratio)) In a mixed solvent, the logarithmic viscosity measured at 30 ° C. is usually preferably 0.05 to 3.0, and more preferably 0.07 to 2.0. Logarithmic viscosity is 0.0
If it is less than 5, the strength of the obtained polymer liquid crystal becomes weak, which is not preferable. On the other hand, when it is more than 3.0, the viscosity at the time of forming the liquid crystal is too high, which causes problems such as deterioration of alignment property and increase of time required for alignment.

The method for synthesizing these polymers is not particularly limited, and they are synthesized by a known polymerization method in the art, for example, a melt polymerization method or an acid chloride method using a corresponding acid chloride of dicarboxylic acid. When synthesized by the melt polymerization method, for example, it can be produced by polymerizing an acetylated product of a corresponding dicarboxylic acid and a corresponding diol at high temperature under high vacuum, and the molecular weight can be easily controlled by controlling the polymerization time or controlling the charging composition. You can do it.

In order to accelerate the polymerization reaction, a conventionally known metal salt such as sodium acetate can be used. When the melt polymerization method is used, the desired polyester can be easily obtained by dissolving a predetermined amount of dicarboxylic acid dichloride and diol in a solvent and heating in the presence of an acid acceptor such as pyridine.

Regarding functional groups contained in a homeotropically aligned liquid crystalline polymer or a homogeneously aligned liquid crystalline polymer chain and capable of being polymerized or crosslinked by light or heat, and the method of polymerizing / crosslinking the same, see Nippon Kagaku Co., Ltd. Meeting,
It is possible to use the method described in all chapters of Experimental Chemistry Course, Volume 28, Polymer Synthesis, Published by Academic Publishing Center (1994), but in particular, the crosslinked polymer of Chapter 9 (from page 425) The method of page 452) can be preferably used.

However, from the viewpoint of intermolecular interaction and steric effect, a functional group which does not hinder the formation of a liquid crystalline polymer is required, and the linearity is high, and the following functional group is easily incorporated into the polymer main chain. The constitutional units as exemplified are preferably used.

[0085]

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[0086]

[Chemical 31]

Further, a method of polymerizing and crosslinking with a functional group in a homeotropically aligned liquid crystalline polymer or a homogeneously aligned liquid crystalline polymer chain and a crosslinking agent added as a third substance is also preferably used. Examples of preferred structural units in the polymer chain in that case include:

[0088]

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Examples of the coexisting cross-linking agent include

[0090]

[Chemical 33]

The functional groups such as acrylate and oxirane, which are thermally stable and easily photopolymerized, are more preferably used. In addition, since the chloromethyl group substituted on the aromatic ring undergoes radical decomposition by an electron beam or X-ray to cause a crosslinking reaction, the following structural units are also preferably used.

[0092]

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When hexavalent chromium is allowed to coexist in a liquid crystalline polymer containing a secondary alcohol as a constitutional unit, a redox reaction and a crosslinking reaction simultaneously proceed in the following scheme.

[0094]

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In addition to the method described above, it is also possible to add a polymerizable third substance, align the liquid crystalline polymer, and then polymerize it by heat or light to form a film. In this method, there are polymerization of a monomer and cross-linking polymerization of a polymer and a cross-linking agent. However, these methods have almost no influence on the orientation of the liquid crystal, and therefore there is almost no limitation in selection of the method. The mixing ratio of the homeotropic alignment liquid crystalline polymer and the homogeneous alignment liquid crystalline polymer varies depending on the polymer and depending on the purpose and cannot be generally specified, but it is usually 99: by weight.
1-0.5: 99.5, more preferably 95: 5-2:
98. In general, the more polymerizable functional groups, including the third substance, the more preferable. Further, it is preferable that all the constituent substances have a polymerizable functional group, rather than only a single substance having a large number of polymerizable functional groups. In that case, the polymerizable functional group is preferably 2% or more and less than 50% in the case of a polymer, and preferably 100% in the case of a monomer.

By applying the method of the present invention, it is possible to utilize various liquid crystalline polymers which have not been neglected in terms of durability, although they are conventionally low in liquid crystal formation temperature, that is, preferable in terms of production suitability. By making it possible to further broaden the range of characteristic control, more suitable optical characteristics and durability can be achieved at the same time. Polymerization of the polymer composition used in the present invention is generally carried out after the liquid crystal exhibits preferable optical anisotropy, that is, after it is in a state on the alignment film. After the orientation, the temperature can be further raised by several tens of degrees and fixed by thermal polymerization. However, radical polymerization by ultraviolet rays and cationic polymerization generally have a very high polymerization rate and are preferable in terms of productivity in the manufacturing process. As the light rays for polymerization, electron rays, ultraviolet rays, visible rays, and infrared rays (heat rays) can be used as necessary, but ultraviolet rays are generally used. The light sources include low-pressure mercury lamps (germicidal lamps, fluorescent chemical lamps, black lights), high-pressure discharge lamps (high-pressure mercury lamps, metal halide lamps), and short arc discharge lamps (ultra-high-pressure mercury lamps, xenon lamps, and mercury xenon lamps). No.

When the thin film of the present invention is formed on a substrate, it is desirable that the material of the substrate is close to optical isotropy in addition to having a good light transmittance. Therefore, a substrate formed of a material having a small intrinsic birefringence value such as glass, Zeonex (Nippon Zeon), ARTON (Nippon Synthetic Rubber), and Fujitac (Fuji Film) is preferable. However, even for materials with large intrinsic birefringence such as polycarbonate, polyacrylate, polysulfone, and polyethersulfone, it is possible to form an optically isotropic substrate by controlling the molecular orientation during film formation. And they are also preferably used. In addition, it is a well-known fact in the case of rod-shaped liquid crystals that a protective film provided in advance on a substrate often exerts a great influence on the molecular alignment at the time of forming a liquid crystal layer as an alignment film. Almost always used as an alignment film. This is one of the techniques preferably used in the present invention, a typical example of which is a SiO oblique deposition film as the metal oblique deposition film, and a rubbed polyimide film as the organic alignment film. In addition, a rubbed modified poval, a rubbed glass substrate treated with a silylating agent, or a rubbed gelatin film is used. However, instead of rubbing, a method in which a polyvinyl alcohol thin film is stretched 4 to 5 times, or a glass substrate is directly rubbed without providing the above protective film can be used.

When the liquid crystalline polymer composition thus obtained is oriented on a substrate, it is possible to realize an intermediate tilted orientation, which is neither conventional homeotropic orientation nor homogeneous orientation. That is, the long axes of the polymer molecules constituting the composition can be oriented so that they are different from the substrate surface and the substrate normal direction. Furthermore, by introducing an optically active unit into the polymer or by allowing an optically active substance to coexist in the composition, a structure having a twisted structure (helical structure) while being tilted can be realized. It has novel optical properties due to the structure that was not previously obtained by the immobilization product by further polymerization of these peculiar orientation structures, and has both practical manufacturing suitability and high durability, and can be used for various optical applications. , Has a great industrial value.

When the thin film obtained according to the present invention is used as an optically anisotropic element, the viewing angle of the liquid crystal display element can be greatly improved, which is estimated as follows. Most TN-LCDs adopt a normally white mode. In this mode, the transmittance of light from the black display portion remarkably increases as the viewing angle increases, resulting in a sharp decrease in contrast. The black display is the state when a voltage is applied, but at this time, the TN type liquid crystal cell can be regarded as a positive uniaxial optical anisotropic body in which the optical axis is slightly inclined from the direction normal to the cell surface. Further, in the case of intermediate gradation, it is considered that the optical axis thereof is further inclined from the normal line direction of the LC cell. When the optical axis of the liquid crystal cell is tilted from the direction normal to the surface of the liquid crystal cell, it is expected that the optical anisotropic body having the optical axis in the normal direction will be insufficiently compensated. For these reasons, it is presumed that the negative uniaxial optical anisotropic body in which the optical axis is tilted from the normal direction in the present invention significantly improves the viewing angle characteristics.

[0100]

EXAMPLES Examples will be described below, but the present invention is not limited to these examples. Example 1 100 mmol of terephthalic acid, 50 mmol of hydroquinone diacetate, 50 mmol of tert-butylcatechol diacetate and 100 mg of sodium acetate were used to perform polymerization at 300 ° C. for 1 hour under a nitrogen atmosphere.
Next, the obtained polymer was dissolved in tetrachloroethane and then reprecipitated with methanol to obtain purified polymer 25.
0 g (P-1) was obtained. It had a nematic phase as a liquid crystal phase and had a glass transition point of 130 ° C.

[0101]

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Using this polyester, a 10 wt% tetrachloroethane solution was prepared. This solution was applied onto a soda glass plate, dried, and then heat-treated at 220 ° C. for 30 minutes and then cooled to obtain a uniformly aligned liquid crystal film.
The polymer was homeotropically oriented.

Example 2 Polymer (P-2) was synthesized. It had a nematic phase as a liquid crystal phase and had a glass transition point of 105 ° C. Using this polyester, a 10 wt% tetrachloroethane solution was prepared, applied to various orientation test substrates, dried, and then heat-treated at 250 ° C. for 30 minutes. As a substrate,
Soda glass, borosilicate glass, polyethylene terephthalate film, and polyimide film were used, but all substrates had homogeneous orientation.

[0104]

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Example 3 5 g of polymer (P-1), 5 g of polymer (P-2), 1 g of epoxy-based monomer (M-1) and 20 m of photopolymerization initiator (diphenyliodonium tetrafluoroborate)
g was dissolved in 90 g of tetrachloroethane, and the solution was applied to a glass substrate having a rubbing polyimide film and dried. After treating at 220 ° C. for 5 minutes, at 80 ° C., an ultraviolet irradiation device (ULTRA-VIOLET PRODUCTS
UVSL-58 (16W) manufactured by the same company was used, and after light exposure for 10 minutes, it was cooled to obtain a transparent film of 7 μm. This film was insoluble in chloroform and showed no glass transition point at 150 ° C or lower. The sample is placed between two parallel polarizing plates (transmission axes intersect by 90 °), the polarizing plates are tilted with respect to the incident light, and the relationship between the tilt angle θ and the apparent retardation value is obtained. It was found that an asymmetric curve was obtained when incident perpendicularly to (θ = 0), and the liquid crystal molecules had a structure tilted with respect to the substrate. Further, it was estimated by simulation that the apparent average tilt angle was 7 ° with respect to the substrate.

[0106]

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Comparative Example 1 5 g of polymer (P-1) and 9 g of polymer (P-2) were used.
It was dissolved in 0 g of tetrachloroethane, and the solution was applied to a glass substrate having a rubbing polyimide film and dried. It was treated at 220 ° C. for 5 minutes and then cooled to obtain a transparent film. This film dissolves in chloroform and exhibits a glass transition point between 90 and 105 ° C. The glass transition point is increased by the polymerization of the coexisting monomer of Example 3, and heat resistance and solvent resistance are improved. I understand.

Example 4 A homeotropically oriented polymer (P-3) and a homogeneously oriented polymer (P-4) were synthesized by an acid chloride method, and these were mixed at a weight ratio of 1: 9 to prepare tetrachloroethane and phenol. Was dissolved in a mixed solvent (4: 6 in weight ratio) to prepare a 15 wt% polymer solution. After coating, drying and heat treatment on a glass substrate having a rubbing polyimide film, an ultraviolet irradiation device (ULTRA-VIOLET)
UVSL-58 (16W) manufactured by PRODUCTS was used, and after light exposure for 20 minutes, it was cooled to obtain a tilt-aligned polymer film (PA). This film was insoluble in chloroform and showed no glass transition point at 150 ° C or lower.

[0109]

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Comparative Example 2 The homeotropic orienting polymer (P-3) and the homogeneous orienting polymer (P-4) were mixed in a weight ratio of 1: 9, and a mixed solvent of tetrachloroethane and phenol (weight ratio 4: 6). ), And a 15 wt% polymer solution was prepared. It was applied onto a glass substrate having a rubbing polyimide film, dried, heat-treated and then cooled to obtain a tilt-oriented polymer film (P-B). This film was dissolved in chloroform and showed a glass transition point at 85 to 100 ° C. The polymer film (P-A) of Example 4 is obtained by photopolymerizing the polymer film (P-B), and this treatment raises the glass transition point and also improves heat resistance and solvent resistance. I understand.

[0111]

From the above examples, the polymer film obtained by the method of the present invention has a high glass transition point and is superior in heat resistance and solvent resistance to conventional ones. It is apparent that a thin film can be used to provide a more durable liquid crystal display device.

Claims (5)

[Claims] 1. A liquid crystal polymer composition comprising at least a homeotropic alignment liquid crystalline polymer and a homogeneous alignment liquid crystalline polymer, one of which has a functional group capable of being polymerized or crosslinked by light or heat. A liquid crystalline polymer composition having: 2. A liquid crystal polymer composition comprising a homeotropic alignment liquid crystal polymer and a homogeneous alignment liquid crystal polymer together with at least a substance capable of being polymerized or crosslinked by light or heat. 3. A method for producing a thin film, comprising forming a thin film comprising the liquid crystalline polymer composition according to claim 1 or 2 and then hardening the thin film by polymerizing or crosslinking by light or heat. 4. A method for producing a thin film, which comprises forming a thin film of a polymer composition containing a polyester-type liquid crystalline polymer and then hardening the thin film by polymerizing or crosslinking by light or heat. 5. A liquid crystal display element comprising a liquid crystal cell and a polarizing plate, wherein the thin film obtained by the manufacturing method according to claim 3 or 4 is used as an optically anisotropic element.