JPH1164856A - Composite film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a liq. crystal orienting film having ability to orient liq. crystal molecules without rubbing by incorporating a polymer obtd. by reacting a specified polymer with a compd. having a liq. crystal forming group and a liq. crystal. SOLUTION: The composite film contains a polymer obtd. by reacting a polymer consisting essentially of repeating units represented by formula I with a compd. having a liq. crystal forming group represented by formula II and a liq. crystal. In the formula II, R is 3-20C alkylene and X is -CN or -OCH3 . A functional silane-contg. compd. or an epoxy group-contg. compd. may be added to a polymer soln. so as to improve adhesiveness to the surface of a substrate when the composite film is formed by coating the surface of the substrate with the soln. The composite film is suitably used as a liq. crystal orienting film capable of orienting liq. crystal molecules without carrying out rubbing. The composite film itself may be used as a liq. crystal compsn. so as to assemble a liq. crystal display device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a composite membrane. More specifically, the present invention relates to a composite film suitable as a liquid crystal alignment film capable of aligning liquid crystal molecules without rubbing.

[0002]

2. Description of the Related Art At present, as a liquid crystal display device, a liquid crystal alignment film is formed on the surface of a substrate on which a transparent conductive film is provided to form a substrate for a liquid crystal display device. In it, for example, a layer of a nematic liquid crystal having a positive dielectric anisotropy is formed to form a cell having a sandwich structure,
A so-called TN in which the major axis of the liquid crystal molecules is continuously twisted by 90 degrees from one substrate toward the other substrate.
2. Description of the Related Art A TN liquid crystal display device having a (Twisted Nematic) liquid crystal cell is known. Orientation of liquid crystal molecules in a liquid crystal display device such as a TN type liquid crystal display device is usually realized by a liquid crystal alignment film provided with an alignment ability for liquid crystal molecules by a rubbing process.

[0003] However, the following problems are pointed out in this rubbing treatment: Since the TFT device is destroyed, measures are taken against static electricity in the manufacturing apparatus. Is not perfect, the rubbing treatment generates dust, which subsequently requires cleaning and increases the number of steps. In an alignment film having a step portion, the rubbing conditions for the step portion and the flat portion become different. Therefore, the alignment control force and the tilt angle are likely to be non-uniform, the rubbing direction is single, and the process of manufacturing an alignment film composed of divided alignment pixels becomes complicated. For a large substrate, for example, 550 × 650 mm or more, In order to uniformly rub the alignment film of a large substrate, a special device is required.

On the other hand, polymer liquid crystals comprising a mixture containing a polymer compound and a liquid crystal are known. JP-A-62-260
No. 841 discloses a ferroelectric composite film made of a ferroelectric liquid crystal mixture comprising a thermoplastic resin and at least two of a specific azomethine liquid crystal, an azoxy liquid crystal, and an ester liquid crystal. Japanese Patent Application Laid-Open No. 2-75691 discloses that a dimming phase in which a nematic liquid crystal material composed of two specific compounds forms a continuous phase and a transparent solid substance is dispersed therein has an electrode layer. A liquid crystal device supported between two substrates is disclosed. JP-A-2-127
No. 494 discloses the following formula:

[0005]

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[0006] Here, a liquid crystalline composition comprising a polymer compound having a repeating unit represented by the following formula: m is 3 or 6, and 4-cyanophenyl-4- (hexyloxy) benzoate is disclosed. . After the liquid crystalline composition itself is formed into a film, it is sandwiched between opposing substrates with a conductive film to form a liquid crystal optical element.

Japanese Patent Application Laid-Open No. 5-53153 discloses a mixed film containing a side chain type polymer liquid crystal in which a side chain mesogen corresponding to a liquid crystal material is grafted on a polymer main chain, a low molecular weight liquid crystal, and an electrolyte. A liquid crystal display element narrowed by a pair of transparent electrodes is disclosed. As the side chain type polymer liquid crystal, the following formula

[0008]

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Here, m is a positive number, and a and b are

[0010]

(Equation 1)

Any positive number that satisfies, R is -CN,-
A polymer having a repeating unit represented by and representing an arbitrary substituent such as OCH ₃ is exemplified.

[0012]

An object of the present invention is to provide a novel liquid crystal alignment film. It is another object of the present invention to provide a liquid crystal alignment film having alignment ability for liquid crystal molecules without rubbing. It is still another object of the present invention to provide a liquid crystal alignment film having an alignment ability for liquid crystal molecules without decomposing molecules on the surface of the alignment film and without having irregularities or undulations on the surface. Still other objects and advantages of the present invention will become apparent from the following description.

[0013]

According to the present invention, the above objects and advantages of the present invention are as follows: (A) (a-1)

[0014]

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A polymer mainly composed of a repeating unit represented by the following formula (a-2):

[0016]

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Wherein R is an alkylene group having 3 to 20 carbon atoms and X is --CN or --OCH ₃ , a compound having a liquid crystal forming group represented by the following formula: , And (B) a liquid crystal. The composite film of the present invention comprises a mixture containing the polymer (A) and the liquid crystal (B). Also,
The polymer (A) comprises a reaction product of the polymer (a-1) and a compound having a liquid crystal forming group.

The polymer (a-1) mainly comprises a repeating unit represented by the above formula (1). The repeating unit represented by the above formula (1) is preferably at least 50 mol%, more preferably at least 70 mol%, further preferably at least 80 mol%, and most preferably substantially based on all repeating units. 100 mol%. The repeating unit represented by the above formula (1) is composed of 1,3-bis (3-aminopropyl) tetramethyldisiloxane and 2,3,5-tricarboxycyclopentylacetic acid dianhydride, for example, N-methylpyrrolidone By reacting in an aprotic polar solvent such as 1,3-Bis (3-aminopropyl) tetramethyldisiloxane and 2,3,5-tricarboxycyclopentylacetic acid dianhydride are preferably used in a ratio of 1 to 1.2 moles of the latter to 1 mole of the former. Used.

The polymer (a-1) has a number average molecular weight of preferably from 1,000 to 1,000,000, more preferably from 5,000 to 500,000. Other repeating units other than the repeating unit represented by the above formula (1) are, for example, 1,5-bis (3-aminopropyl) hexamethyltrisiloxane, 1,3-bis (3-aminopropyl) tetraphenyldisiloxane Examples include units obtained by reacting a diamino compound such as siloxane with tricarboxycyclopentylacetic acid dianhydride.

The compound (a-2) having a liquid crystal forming group is
It is represented by the above equation (2). In the formula (2), R is a group having 3 to 3 carbon atoms.
20 alkylene groups. Such an alkylene group may be linear or branched, for example, trimethylene, 1,2-propylene (any of the following formulas),

Embedded image 1,4-tetramethylene, 1,5-pentamethylene, 1,
6-hexamethylene, 1,8-octamethylene, 1,9-
Nonamethylene, 1,10-decamethylene, 1,16-hexadecamethylene and the like can be mentioned. In the formula (2), X is -CN or -OCH _3.

The compound represented by the formula (2) is, for example, p-
An alkyl hydroxybenzoate and an alkenyl halide such as pentenyl bromide are reacted in the presence of an acid scavenger such as potassium carbonate to produce an alkyl p-alkenyloxybenzoate, which is hydrolyzed to a free acid to form an acid halide. The compound can be prepared by reacting 4-cyano or methoxyphenol with a basic compound such as pyridine, and finally oxidizing to epoxide. The polymer (a-1) and the compound (a-2) are preferably at least 50 mol%, more preferably at least 70 mol% of the repeating unit represented by the formula (1) of the polymer (a-1). Particularly preferably, 80 mol% or more is used so as to give a polymer (A) reacted with the compound of the formula (2).

In the polymer (A), the epoxy group of the compound (a-2) reacts with the carboxyl group of the repeating unit represented by the formula (1) to form a reaction unit of the compound (a-2). It has a structure forming a side chain of (a-1). The polymer (A) preferably has a number average molecular weight of 1,000 to 1,000.
1,000,000, more preferably 10,000 to 1.0
00,000. In the present invention, various types of liquid crystal (B) can be used. Preferably, 4-cyano or methoxyphenyl-4- (alkyloxy) benzoate, 4-cyano or methoxy-4′-alkylbiphenylene or triphenylene is used. These can be used alone or as a mixture of two or more.

The polymer (A) and the liquid crystal (B) preferably have a content of the liquid crystal (B) of 0.5 to 5 mol, more preferably 1 to 2 per 1 mol of the repeating unit (1) of the polymer (A). It is used in a molar ratio. When the ratio of the liquid crystal to the polymer (A) is less than 0.5 mol, it is difficult to obtain a composite film having a small liquid crystal aligning ability and sufficient liquid crystal aligning ability. It becomes difficult to obtain a self-supporting composite membrane. The composite film of the present invention is formed by applying a polymer solution obtained by dissolving a polymer (A) and a liquid crystal (B) in an organic solvent to a substrate surface by a printing method, a spin coating method, and the like, and then drying the solution. can do.

The organic solvent is not particularly limited as long as it can dissolve the polymer (A) and the liquid crystal (B).
Aprotic polar solvents such as N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, dimethylsulfoxide, γ-butyrolactone, tetramethylurea, hexamethylphosphortriamide; Phenolic solvents such as cresol, xylenol, phenol and halogenated phenol can be mentioned. The solid content concentration in the polymer solution is selected in consideration of viscosity, volatility and the like, but is preferably in the range of 0.1 to 20% by weight, more preferably 1 to 10% by weight. Solid content is 0.1% by weight
If it is less than 10%, the thickness of the organic film may be too small to obtain a good composite film. If it exceeds 20% by weight, the thickness of the organic film may be too large. In some cases, it is difficult to obtain a good composite film, and the viscosity of the coating solution may increase, resulting in poor coating characteristics.

From the viewpoint of improving the adhesion to the substrate surface when the composite film of the present invention is formed by coating on the substrate surface, a functional silane-containing compound or an epoxy group-containing compound is contained in the polymer solution. May be blended. Examples of such a functional silane-containing compound include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 2-aminopropyltrimethoxysilane, 2-aminopropyltriethoxysilane, N- (2
-Aminoethyl) -3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-ureidopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, N-ethoxycarbonyl -3-aminopropyltrimethoxysilane, N-ethoxycarbonyl-3-aminopropyltriethoxysilane, N-triethoxysilylpropyltriethylenetriamine, N-trimethoxysilylpropyltriethylenetriamine, 10-trimethoxysilyl-1, 4,7-triazadecane, 10-triethoxysilyl-1,4,7-triazadecane, 9-trimethoxysilyl-3,6-diazanonyl acetate, 9-
Triethoxysilyl-3,6-diazanonyl acetate, N-benzyl-3-aminopropyltrimethoxysilane, N-benzyl-3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, N -Phenyl-3-aminopropyltriethoxysilane, N-bis (oxyethylene) -3-aminopropyltrimethoxysilane, N-bis (oxyethylene) -3-aminopropyltriethoxysilane, and the like. Further, as the epoxy group-containing compound, for example, ethylene glycol diglycidyl ether,
Polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerin diglycidyl ether,
2,2-dibromoneopentyl glycol diglycidyl ether, 1,3,5,6-tetraglycidyl-2,4-hexanediol, N, N, N ', N'-tetraglycidyl-m-xylenediamine, 1 , 3-Bis (N, N-diglycidylaminomethyl) cyclohexane, N, N, N ',
N ',-tetraglycidyl-4,4'-diaminodiphenylmethane and the like can be mentioned as preferred. The compounding ratio of these functional silane-containing compounds and epoxy group-containing compounds is usually 40 parts by weight or less, preferably 0.1 to 30 parts by weight, based on 100 parts by weight of the polymer.

The composite film of the present invention is suitably used as a liquid crystal alignment film that enables alignment of liquid crystal molecules without rubbing. In addition, it is possible to assemble a liquid crystal display element using the composite film itself as a liquid crystal composition.

The liquid crystal alignment film is advantageously implemented, for example, as follows. On the transparent conductive film side of the substrate on which the patterned transparent conductive film is provided, apply the polymer solution by a method such as a roll coater method, a spinner method, a printing method, and then heat the coated surface to form a film. To form Here, as the substrate, for example, a transparent substrate made of glass such as float glass or soda glass, or a plastic film of polyethylene terephthalate, polybutylene terephthalate, polyether sulfone, polycarbonate, polyarylate, norbornene-based resin, or the like can be used. The transparent conductive film provided on one surface of the substrate is NESA made of SnO _2.
A film, an ITO film made of In ₂ O ₃ —SnO _2, or the like can be used.
A photo-etching method, a method using a mask in advance, or the like is used.

In applying the polymer solution, a functional silane-containing compound, titanate, or the like is previously applied onto the substrate and the transparent conductive film in order to further improve the adhesion between the substrate and the transparent conductive film. You can also. The heating temperature is preferably from 80 to 250 ° C, and more preferably from 120 to 200 ° C. The thickness of the formed film is usually 0.001 to 1 μm, preferably 0.005.
〜0.5 μm. Next, in order to manufacture a liquid crystal display element from a substrate, two substrates on which a liquid crystal alignment film is formed as described above are prepared, and a gap (cell gap) is formed between the two substrates.
The peripheral portions of the two substrates are bonded together with a sealant, the surface of the substrate and the cell gap defined by the sealant are filled with liquid crystal, and the filling hole is sealed to form a liquid crystal cell. Is configured. Then, a liquid crystal display element is obtained by attaching a polarizing plate to the outer surface of the liquid crystal cell, that is, the other surface of each of the substrates constituting the liquid crystal cell, so that the polarization directions thereof are the same or orthogonal.

As the sealing agent, for example, an epoxy resin containing a hardening agent and aluminum oxide spheres as spacers can be used. Examples of the liquid crystal include a nematic liquid crystal and a smectic liquid crystal. Among them, nematic type liquid crystals are preferable. Liquid crystal, cubane liquid crystal, and the like are used. In addition, cholesteric liquid crystals such as cholesteryl chloride, cholesteryl nonaate, cholesteryl carbonate, and the product name “C-
15 "and" CB-15 "(manufactured by Merck & Co., Inc.). In addition, ferroelectric liquid crystals such as p-decyloxybenzylidene-p-amino-2-methylbutylcinnamate can be used. In addition, the polarizing plate used outside the liquid crystal cell includes a polarizing plate or a H film itself in which a polarizing film called an H film that absorbs iodine and sandwiched by a cellulose acetate protective film while stretching and aligning polyvinyl alcohol is used. A polarizing plate and the like can be given.

[0030]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. Example 1 (1) Synthesis of Compound (a-2) Having Liquid Crystal-Forming Group Methyl p-hydroxybenzoate 2 in 50 ml of acetone
5 g (0.17 mol) and 25 g of pentenyl 4-bromide
(0.17 mol) was dissolved, 47 g of potassium carbonate was added, and the mixture was heated under reflux for 10 hours. The reaction product was poured into a large amount of water, and the resulting oil was extracted and recovered twice with diethyl ether. The ether phase was washed with water and dried over anhydrous sodium sulfate, and ether was distilled off to obtain 35 g (91%) of crude methyl p-pentenoxybenzoate. 33 g (0.15 mol) of this crude product was dissolved in 150 ml of ethanol, 58 g of a 13% aqueous sodium hydroxide solution was further added, and the mixture was stirred for 13 hours. 1 l of this solution with water
After that, p-pentenoxybenzoic acid was precipitated by adding 5N hydrochloric acid until the solution became acidic. This coarse p-
The pentenoxybenzoic acid was separated by filtration, collected, washed with water and dried. The yield was 29 g (94%).

Further, 35 ml of thionyl chloride was added thereto, and the mixture was heated under reflux until the liquid became homogeneous, and thionyl chloride was distilled off to obtain 28 g (89%) of p-pentenoxybenzoic acid chloride. This was dissolved in 250 ml of chloroform, 15 g of 4-cyanophenol and 13 g of pyridine were further added, and the mixture was stirred at room temperature for 2 hours. This solution is water,
After washing with 0.1N hydrochloric acid and a 5% aqueous sodium hydrogen carbonate solution in that order and drying over anhydrous sodium sulfate, chloroform was distilled off. The remaining white solid was recrystallized from ethanol to obtain 22 g (57%) of p-pentenoxybenzoic acid (p-cyanophenyl). 22g (70mmo
l) p-Pentenoxybenzoic acid (p-cyanophenyl) is dissolved in 200 ml of chloroform, and 18 g of m-chloroperbenzoic acid (70%) and 6
Then, 30 ml of 30% aqueous hydrogen peroxide was added, and the mixture was stirred at room temperature for 18 hours. The reaction mixture was sequentially washed with water, an aqueous solution of sodium thiosulfate and an aqueous solution of sodium hydrogen carbonate, dried over anhydrous sodium sulfate, and the solvent was distilled off to obtain crude p-pentenoxybenzoic acid (p-cyanophenyl) oxide. This was recrystallized with ethanol to obtain 16 g (71%) of a purified product.

(2) Synthesis of polymer (a-1) 2,3-, 5-Tricarboxycyclopentylacetic acid dianhydride and 1,3-bis (3-aminopropyl) tetramethylene disiloyl were added to N-methylpyrrolidone. The mixture was mixed with an equimolar so as to have a solid concentration of 10% by weight and stirred at room temperature for 24 hours to prepare a polyamic acid solution.

(3) Synthesis of polymer (A) The compound (a-2) obtained in the above (1) was added to the solution obtained in the above (2) in an amount of 1 mol per 1 mol of the repeating unit of the polyamic acid. And reacted by heating at 200 ° C. for 6 hours.

(4) Production of composite film composed of polymer (A) / liquid crystal (B) As the liquid crystal, a mixed nematic liquid crystal E7 having the following composition was used.
(A product of Merck) was used.

[0035]

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The average molecular weight of E7 was 271.36, and 1 mol of the liquid crystal E7 was mixed per 1 mol of the repeating unit of the polymer obtained in the above (3). As the casting solvent, NMP used for polymer synthesis was used. Make the solution concentration 4%, and use a flat petri dish on a hot plate.
The solvent was evaporated at 00 ° C. to form a film.

(5) Characteristics of Composite Film According to scanning calorimetry (DSC), it is understood that this composite film has no melting point (Tm) and liquid crystal molecules are dispersed in a molecular form. You.・ To study the phase structure of liquid crystal in the composite film,
Polarization microscope observation was performed while changing the temperature under crossed Nicols. In any temperature range, it was dark field under crossed Nicols, and it was confirmed that the composite film was an isotropic phase. Despite the fact that no liquid crystal phase was observed despite the liquid crystal being mixed, it was considered that the liquid crystal had evaporated during casting. Gas chromatography was measured. As a result, a peak corresponding to the liquid crystal molecule was detected from the composite film, and it was confirmed that the liquid crystal molecule was certainly contained in the composite film showing the isotropic phase. Further, no formation of a smectic phase was confirmed. Observation by a polarizing microscope also strongly supported that the liquid crystal molecules were dispersed in a molecular state. X-ray diffraction X-ray diffraction measurement was performed to confirm the liquid crystal phase structure in the composite film, and the formation of a smectic phase structure was examined. (The X-ray diffraction measurement was requested to Act Research Co., Ltd.). In 2θ scan: 3 ° to 80 °), a diffraction peak was detected to confirm the presence or absence of phase structure formation. From the X-ray diffraction pattern, it can be seen that 0.4 to 0.5 nm
Only an amorphous pattern was observed, and no diffraction pattern showing a long-period structure derived from the layered structure due to the smectic phase was observed.・ Characteristic evaluation of liquid crystal cell using composite film as amorphous alignment film A liquid crystal cell was prepared using the composite film. Cell thickness is 5.5μ
m, the cells were assembled in the TN mode, and the liquid crystal pitch was set to の of the cell thickness (pitch = 1.38 μm). Regardless of the presence or absence of rubbing, the liquid crystal in the cell does not align uniformly,
It was expected to function as an amorphous alignment film.
This liquid crystal cell was subjected to transmittance-voltage characteristics (T-
FIG. 1 shows the results obtained by measuring the V characteristics. It was confirmed that light / dark switching was exhibited regardless of rubbing. In addition, although there was a slight voltage shift as compared with a commercially available liquid crystal alignment film, almost the same TV characteristics were obtained.

[0038]

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between transmittance and voltage measured for a liquid crystal cell using a liquid crystal alignment film comprising a composite film of the present invention.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yasuo Matsuki 2-11-24 Tsukiji, Chuo-ku, Tokyo Inside Nippon Gosei Rubber Co., Ltd.

Claims (1)

[Claims] (A) (a-1) The following formula (1): And a polymer mainly composed of a repeating unit represented by the following formula (a-2): Wherein R is an alkylene group having 3 to 20 carbon atoms and X is —CN or —OCH ₃ , a compound having a liquid crystal-forming group represented by the following formula: B) A composite film containing a liquid crystal.