JP2007256483A - Liquid crystal aligning agent and in-plane switching mode liquid crystal display element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal aligning agent excellent in printing property for an in-plane switching mode liquid crystal display element. <P>SOLUTION: The liquid crystal aligning agent for the in-plane switching mode liquid crystal display element contains a soluble polyimide having an imide structure expressed by formula (1), obtained by dehydration cyclization of polyamic acid obtained by the reaction of a tetracarboxylic acid dianhydride and diamine, wherein the imidization rate of the soluble polyimide ranges from 60 to 95%. In formula (1), R<SP>1</SP>represents a tetravalent organic group and R<SP>2</SP>represents a divalent organic group. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a horizontal electric field type liquid crystal display element and a liquid crystal aligning agent therefor. More specifically, the present invention relates to a lateral electric field type liquid crystal display element excellent in afterimage relaxation behavior and a liquid crystal aligning agent therefor.

Currently, as a liquid crystal display element, a liquid crystal alignment film made of polyamic acid, polyimide, or the like is formed on the surface of a substrate on which a transparent conductive film is provided to form a liquid crystal display element substrate. A nematic liquid crystal layer having positive dielectric anisotropy is formed in a cell having a sandwich structure so that the major axis of the liquid crystal molecules is continuously twisted 90 degrees from one substrate to the other. A TN type liquid crystal display element having a so-called TN type (Twisted Nematic) liquid crystal cell is known.
Further, STN (Super Twisted Nematic) type liquid crystal display elements and vertical alignment type liquid crystal display elements, which have a higher contrast than the TN type liquid crystal display elements and have less viewing angle dependency, have been developed. This STN type liquid crystal display element uses nematic liquid crystal blended with a chiral agent which is an optically active substance as liquid crystal, and the major axis of liquid crystal molecules is continuously twisted over 180 degrees between substrates. The birefringence effect generated by the above is utilized.

In recent years, the development of new liquid crystal display elements has also been active, and as one of them, two electrodes for driving a liquid crystal are arranged in a comb shape on one substrate, and an electric field parallel to the substrate surface is arranged. And a horizontal electric field type liquid crystal display element that controls liquid crystal molecules. This element is generally called an in-plane switching type (IPS type), and is known for its excellent wide viewing angle characteristics. Recently, an optical compensation film is used to further improve the wide viewing angle characteristics, so that it is possible to obtain a wide viewing angle comparable to that of a cathode ray tube without tone reversal or color change.
However, as a conventionally known polyamic acid and an imide-based polymer having a structure obtained by dehydrating and ring-closing it, a photo-alignment film proposed in Patent Document 1 and proposed in Patent Document 2 and Patent Document 3 are proposed. When a horizontal electric field type liquid crystal display element is produced using the polyamic acid which is used, alignment failure occurs due to printing failure. This problem is said to be a big fatal point especially for a liquid crystal display with high image quality and large capacity display.
JP-A-9-197411 JP 2003-149648 A JP 2003-107486 A

  An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a horizontal electric field type liquid crystal display element excellent in printability.

  Another object of the present invention is to provide a liquid crystal aligning agent that gives birth to the excellent characteristics of the transverse electric field type liquid crystal display element of the present invention.

  Still other objects and advantages of the present invention will become apparent from the following description.

  According to the present invention, the above objects and advantages of the present invention are as follows. First, the polyamic acid obtained by reacting tetracarboxylic dianhydride and diamine is obtained by dehydrating cyclization.

Where R ¹ is a tetravalent organic group and R ² is a divalent organic group.
It is achieved by a liquid crystal aligning agent for a horizontal electric field mode liquid crystal display device, characterized in that it comprises a soluble polyimide having an imide structure represented by the following formula, and the imidization ratio of the soluble polyimide is 60 to 95%: The
According to the present invention, the above objects and advantages of the present invention are secondly achieved by a horizontal electric field type liquid crystal display device comprising a liquid crystal alignment film obtained from the liquid crystal aligning agent of the present invention.

  One of the problems in the horizontal electric field type liquid crystal display element is a printing failure of the alignment agent. In a horizontal electrolysis type liquid crystal display element, an alignment film is formed on a comb-like electrode formed on a substrate. The poor printing of the alignment agent on the comb-like electrode causes a deterioration in quality as a display element. Since the liquid crystal aligning agent of this invention is excellent in the printability of the aligning agent on a board | substrate, this subject point is solved. As a result, a liquid crystal display element having an alignment film formed using the liquid crystal aligning agent of the present invention can be used effectively in various devices because a liquid crystal alignment film suitable for a horizontal electric field type liquid crystal display element can be obtained. For example, it is used for display devices such as desk calculators, watches, table clocks, counting display boards, word processors, personal computers, mobile phones, and liquid crystal televisions.

Hereinafter, the present invention will be described in detail. The soluble polyimide used in the liquid crystal aligning agent for horizontal electric field type liquid crystal display elements of the present invention (hereinafter also simply referred to as “liquid crystal aligning agent of the present invention”) is preferably a tetracarboxylic dianhydride and a diamine compound, preferably organic. It is a soluble polyimide having an imidization ratio of 60 to 95%, which can be obtained by partially dehydrating and cyclizing a polyamic acid obtained by reaction in a solvent. A resin solution obtained by dissolving this soluble polyimide in an organic polar solvent is applied onto a glass substrate having a comb-like ITO film on one side and a normal glass substrate as a counter substrate, and then dried and baked to obtain a polyimide. A film is formed, and the film surface is subjected to an alignment treatment such as rubbing to be used as a liquid crystal alignment film.
In the horizontal electric field type liquid crystal display element, the printability on the electrode substrate is generally a problem, but the liquid crystal aligning agent of the present invention is excellent as a horizontal electric field type liquid crystal display element because it has good printability. Display performance.

Specific examples of tetracarboxylic dianhydrides used in the synthesis of polyamic acid for the soluble polyimide of the present invention include pyromellitic dianhydride, 3-trifluoromethylpyromellitic dianhydride, benzophenone tetracarboxylic Acid dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyl ether tetra Aromatic tetracarboxylic such as carboxylic dianhydride, 4,4'-bis (3,4-dicarboxyphenoxy) diphenylpropane dianhydride, 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride Acid dianhydride; 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride Objects, and the like 2,3,5 carboxymethyl alicyclic such as cyclopentyl acetic dianhydride tetracarboxylic dianhydride. Among these, 2,3,5-tricarboxycyclopentyl acetic acid dianhydride and pyromellitic dianhydride are particularly preferable.
These tetracarboxylic dianhydrides may be used alone or in admixture of two or more. 2,3,5-Tricarboxycyclopentylacetic acid dianhydride is used alone as the tetracarboxylic dianhydride, or preferably 20% by weight or more, more preferably 50% by weight or more, and other tetracarboxylic dianhydrides. It is preferably used as a mixture with an anhydride.

Specific examples of the diamine used in the present invention include p-phenylenediamine, m-phenylenediamine, 4,4′-diaminodiphenylmethane, 4,4′-diaminobiphenyl, 2,2′-dimethyl-4,4 ′. -Diaminobiphenyl, 2,2'-ditrifluoromethyl-4,4'-diaminobiphenyl, 4,4'-diaminodiphenyl ether, 1,5-diaminonaphthalene, 4,4'-diaminobenzophenone, 2,2-bis [ Aromatic diamines such as 4- (4-aminophenoxy) phenyl] propane, 1,4-bis (4-aminophenoxy) benzene, 2,7-diaminofluorene, 9,9-bis (4-aminophenyl) fluorene;
Aliphatic and cycloaliphatic diamines such as tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, 1,4-diaminocyclohexane, tetrahydrodicyclopentadienylenediamine, 4,4′-methylenebis (cyclohexylamine);
2,3-diaminopyridine, 2,6-diaminopyridine, 2,4-diamino-6-dimethylamino-1,3,5-triazine, 2,4-diamino-5-phenylthiazole, 3,5-diamino- Examples thereof include diamines having two primary amino groups and nitrogen atoms other than the primary amino group in the molecule, such as 1,2,4-triazole and bis (4-aminophenyl) phenylamine. Among these, p-phenylenediamine, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenyl ether, 2,2-bis [4- (4-aminophenoxy) phenyl] propane and 2,2′-dimethyl -4,4'-diaminobiphenyl is particularly preferred. Moreover, these diamine compounds can be used individually or in combination of 2 or more types. These illustrations do not limit the scope of the present invention.

[Synthesis of polyamic acid]
The ratio of tetracarboxylic dianhydride and diamine used in the polyamic acid synthesis reaction is 0.2 to 2 equivalents of tetracarboxylic dianhydride acid anhydride group to 1 equivalent of amino group of diamine. The ratio is preferably, and more preferably 0.8 to 1.2 equivalent. The polyamic acid synthesis reaction is preferably performed in an organic solvent under a temperature condition of −20 ° C. to 150 ° C., more preferably 0 to 100 ° C.
Here, the organic solvent is not particularly limited as long as it can dissolve the synthesized polyamic acid. For example, 1-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, 3-butoxy-N, N-dimethylpropanamide, 3-methoxy-N, N-dimethylpropanamide, 3-hexyl Amide solvents such as oxy-N, N-dimethylpropanamide, aprotic polar solvents such as dimethyl sulfoxide, γ-butyrolactone, tetramethylurea, hexamethylphosphortriamide; m-cresol, xylenol, phenol, halogenated phenol Examples thereof include phenolic solvents. The amount (α) of the organic solvent used is preferably such that the total amount (β) of the tetracarboxylic dianhydride and the diamine compound is 0.1 to 30% by weight based on the total amount (α + β) of the reaction solution. Such an amount is preferred.

  In addition, the said organic solvent can use together the alcohol, ketone, ester, ether, halogenated hydrocarbon, hydrocarbon, etc. which are poor solvents of a polyamic acid in the range in which the polyamic acid to produce | generate does not precipitate. Specific examples of such poor solvents include, for example, methyl alcohol, ethyl alcohol, isopropyl alcohol, cyclohexanol, 4-hydroxy-4-methyl-2-pentanone, ethylene glycol, propylene glycol, 1,4-butanediol, triethylene glycol. , Ethylene glycol monomethyl ether, ethyl lactate, butyl lactate, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, methyl acetate, ethyl acetate, butyl acetate, methyl methoxypropionate, ethyl ethoxypropionate, diethyl oxalate, malon Acid diethyl, diethyl ether, ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol-n-propyl ether, ethylene glycol-i Propyl ether, ethylene glycol-n-butyl ether, ethylene glycol dimethyl ether, ethylene glycol ethyl ether acetate, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, tetrahydrofuran, dichloromethane 1,2-dichloroethane, 1,4-dichlorobutane, trichloroethane, chlorobenzene, o-dichlorobenzene, hexane, heptane, octane, benzene, toluene, xylene and the like.

  As described above, a reaction solution obtained by dissolving polyamic acid is obtained. The reaction solution is poured into a large amount of poor solvent to obtain a precipitate, and the precipitate is dried under reduced pressure to obtain a polyamic acid. The polyamic acid can be purified by dissolving the polyamic acid again in an organic solvent and then precipitating with a poor solvent once or several times.

[Synthesis of polyimide]
The soluble polyimide constituting the liquid crystal aligning agent of the present invention can be synthesized by dehydrating and ring-closing the polyamic acid. The polyimide used in the present invention is

Where R ¹ is a tetravalent organic group and R ² is a divalent organic group.
It has the imide structure represented by these.
In the above formula (1), the tetravalent organic group of R ¹ corresponds to a residue obtained by removing two acid anhydride groups from tetracarboxylic dianhydride, and the divalent organic group of R ² is derived from a diamine compound. Corresponds to the residue from which the two amino groups have been removed.

The polyimide in the present invention may have the imidized structure with an imidization rate of less than 100%. That is, the amic acid structure may be partially dehydrated and closed. The “imidation ratio” herein is a value representing the ratio of the repeating unit having an imide ring or an isoimide ring in percentage in the total of the imide repeating unit and the amic acid repeating unit of the polymer. The imidization rate is 60 to 95%, preferably 80 to 95%. The polyamic acid is dehydrated and closed by (i) a method of heating the polyamic acid, or (ii) dissolving the polyamic acid in an organic solvent, adding a dehydrating agent and a dehydrating ring-closing catalyst to this solution, and heating as necessary. By the method.
The reaction temperature in the method of heating the polyamic acid (i) is preferably 50 to 200 ° C, more preferably 60 to 170 ° C. When the reaction temperature is less than 50 ° C., the dehydration ring-closing reaction does not proceed sufficiently, and when the reaction temperature exceeds 200 ° C., the molecular weight of the resulting polyimide may decrease.

  On the other hand, in the method (ii) of adding a dehydrating agent and a dehydrating ring-closing catalyst to the polyamic acid solution, an acid anhydride such as acetic anhydride, propionic anhydride, or trifluoroacetic anhydride is used as the dehydrating agent. Can do. Although the usage-amount of a dehydrating agent is based on the desired imidation rate, it is preferable to set it as 0.01-20 mol with respect to 1 mol of repeating units of polyamic acid. Moreover, as a dehydration ring closure catalyst, tertiary amines, such as a pyridine, a collidine, a lutidine, a triethylamine, can be used, for example. However, it is not limited to these. The amount of the dehydration ring-closing catalyst used is preferably 0.01 to 10 mol with respect to 1 mol of the dehydrating agent used. The imidation rate can be increased as the amount of the above dehydrating agent and dehydrating ring-closing agent increases. The imidation ratio is preferably 40 to 100%, more preferably 70 to 100% from the viewpoint of the afterimage relaxation time of the liquid crystal display element. In addition, as an organic solvent used for dehydration ring closure reaction, the same organic solvent illustrated as what is used for the synthesis | combination of a polyamic acid can be mentioned. And reaction temperature of dehydration ring closure reaction becomes like this. Preferably it is 0-180 degreeC, More preferably, it is 10-150 degreeC. Moreover, a polyimide can be refine | purified by performing operation similar to the purification method of a polyamic acid with respect to the reaction solution obtained in this way.

[Logarithmic viscosity of polymer]
The polyamic acid and / or polyimide obtained as described above preferably have a logarithmic viscosity (η _ln ) of 0.05 to 10 dl / g, more preferably 0.05 to 5 dl / g.
The value of the logarithmic viscosity (η _ln ) in the present invention is determined by measuring the viscosity at 30 ° C. for a solution having a concentration of 0.5 g / 100 ml using N-methyl-2-pyrrolidone as a solvent. ).

[Liquid crystal aligning agent]
The liquid crystal aligning agent of the present invention preferably comprises the above polyamic acid and / or polyimide dissolved in an organic solvent. The temperature at the time of preparing the liquid crystal aligning agent of this invention becomes like this. Preferably it is 0 to 200 degreeC, More preferably, it is 20 to 60 degreeC.

  Examples of the organic solvent constituting the liquid crystal aligning agent of the present invention include N-methyl-2-pyrrolidone, γ-butyrolactone, γ-butyrolactam, N, N-dimethylformamide, N, N-dimethylacetamide, 4-hydroxy- 4-methyl-2-pentanone, ethylene glycol monomethyl ether, butyl lactate, butyl acetate, methyl methoxypropionate, ethyl ethoxypropionate, ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol-n-propyl ether , Ethylene glycol-i-propyl ether, ethylene glycol-n-butyl ether (butyl cellosolve), ethylene glycol dimethyl ether, ethylene glycol ethyl ether acetate, diethylene glycol dimethyl Ether, diethylene glycol diethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, 3-butoxy-N, N-dimethylpropanamide, 3-methoxy-N, N-dimethylpropanamide, 3-hexyloxy-N, N-dimethylpropanamide and the like can be mentioned. Of these, 3-butoxy-N, N-dimethylpropanamide, 3-methoxy-N, N-dimethylpropanamide, and 3-hexyloxy-N, N-dimethylpropanamide exhibit particularly good printability. preferable. These organic solvents can be used alone or in combination of two or more. In particular, a mixed solvent of γ-butyrolactone, butyl cellosolve and N-methyl-2-pyrrolidone or 3-butoxy-N, N-dimethylpropanamide is preferable. More preferably, γ-butyrolactone is mixed at a ratio of 75 to 90% by weight, butyl cellosolve at 5 to 15% by weight, and 3-butoxy-N, N-dimethylpropanamide at a ratio of 1 to 15% by weight with respect to the total mixed solvent. Are preferably used.

  The solid content concentration in the liquid crystal aligning agent of the present invention is selected in consideration of viscosity, volatility, etc., but is preferably in the range of 1 to 10% by weight. That is, the liquid crystal aligning agent of the present invention is applied to the substrate surface to form a resin film that becomes a liquid crystal aligning film. When the solid content concentration is less than 1% by weight, the film thickness of the resin film is If the solid content concentration exceeds 10% by weight, the resin film becomes too thick to obtain a good liquid crystal alignment film. In addition, the viscosity of the liquid crystal aligning agent increases, resulting in poor coating characteristics.

  The liquid crystal aligning agent of this invention may contain the functional silane containing compound and the epoxy compound from a viewpoint which improves the adhesiveness with respect to the substrate surface within the range which does not impair the target physical property. Examples of such functional silane-containing compounds include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 2-aminopropyltrimethoxysilane, 2-aminopropyltriethoxysilane, and N- (2-aminoethyl). -3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-ureidopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, N-ethoxycarbonyl-3-amino Propyltrimethoxysilane, N-ethoxycarbonyl-3-aminopropyltriethoxysilane, N-triethoxysilylpropyltriethylenetriamine, N-trimethoxysilylpropyltriethylenetriamine, 10-trimethoxysilyl- , 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, etc. can be mentioned. Examples of such epoxy compounds include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, and 1,6-hexane. Diol 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, '- diaminodiphenylmethane, 3- (N-Ariru N Gurishijiru) aminopropyltrimethoxysilane, 3- (N, N-diglycidyl) and aminopropyl trimethoxy silane can be cited.

[Liquid crystal display element]
The horizontal electric field mode liquid crystal display element of the present invention can be manufactured, for example, by the following method.

(1) The liquid crystal aligning agent of the present invention is applied, for example, to the conductive film forming surface of the substrate provided with the transparent conductive film patterned in a comb-tooth shape and the one surface of the counter substrate not provided with the conductive film. Coating is performed by a method such as a roll coater method, a spinner method, or a printing method, and then the coated surface is heated to form a resin film. Here, as the substrate, for example, glass such as float glass or soda glass; a transparent substrate made of plastic such as polyethylene terephthalate, polybutylene terephthalate, polyethersulfone, or polycarbonate can be used. As a transparent conductive film provided on one surface of the substrate, an NESA film (registered trademark of PPG, USA) made of tin oxide (SnO ₂ ), an ITO film made of indium oxide-tin oxide (In ₂ O ₃ —SnO ₂ ), etc. Can be used. For patterning these transparent conductive films, a photo-etching method or a method using a mask in advance is used. In applying the liquid crystal aligning agent, in order to further improve the adhesion between the substrate surface and the transparent conductive film and the resin film, for example, a functional silane-containing compound or a functional titanium-containing compound is previously applied to the surface of the substrate. It can also be applied. The heating temperature after application of the liquid crystal aligning agent is preferably 80 to 300 ° C, more preferably 120 to 250 ° C. The liquid crystal aligning agent of the present invention forms a resin film that becomes an alignment film by removing the organic solvent after coating. However, when imidization has not progressed completely, dehydration ring closure proceeds by further heating. It is also possible to obtain a more imidized resin film. The film thickness of the formed resin film is preferably 0.001 to 1 μm, more preferably 0.005 to 0.5 μm.

(2) A rubbing process is performed in which the formed resin film surface is rubbed in a certain direction with a roll wound with a cloth made of fibers such as nylon, rayon, and cotton. Thereby, the alignment ability of the liquid crystal molecules is imparted to the resin film to form a liquid crystal alignment film.
Further, by partially irradiating the liquid crystal alignment film formed of the liquid crystal alignment agent of the present invention with ultraviolet rays as disclosed in, for example, JP-A-6-222366 and JP-A-6-281937. A resist film is partially formed on the surface of the liquid crystal alignment film which has been subjected to a treatment for changing the pretilt angle or a rubbing treatment as disclosed in JP-A-5-107544, which is different from the previous rubbing treatment. The visibility characteristics of the liquid crystal display element can be improved by removing the resist film after performing the rubbing treatment in the direction and changing the liquid crystal alignment ability of the liquid crystal alignment film.

(3) A substrate on which the transparent conductive film is formed as described above and a substrate on which the transparent conductive film is not patterned are each manufactured so that the rubbing directions in the respective liquid crystal alignment films are antiparallel. In addition, two substrates are arranged to face each other through a gap (cell gap), and the peripheral portions of the two substrates are bonded together using a sealing agent, and the liquid crystal is formed in the cell gap defined by the substrate surface and the sealing agent. And filling the injection hole to form a liquid crystal cell. Then, a polarizing plate is provided on the outer surface of the liquid crystal cell, that is, the other surface side of each substrate constituting the liquid crystal cell, so that the polarization direction thereof coincides with the rubbing direction of the liquid crystal alignment film formed on one surface of the substrate. By sticking together, a horizontal electric field type liquid crystal display element is obtained.

Here, as the sealing agent, for example, an epoxy resin containing a curing agent and aluminum oxide spheres as a spacer can be used.
Examples of the liquid crystal include nematic liquid crystal and smectic liquid crystal. Among them, nematic liquid crystal is preferable. For example, Schiff base liquid crystal, azoxy liquid crystal, biphenyl liquid crystal, phenyl cyclohexane liquid crystal, ester liquid crystal, terphenyl liquid crystal. Liquid crystals, biphenylcyclohexane liquid crystals, pyrimidine liquid crystals, dioxane liquid crystals, bicyclooctane liquid crystals, cubane liquid crystals, and the like can be used.
Further, as a polarizing plate to be bonded to the outer surface of the liquid crystal cell, a polarizing film or an H film in which a polarizing film called an H film that absorbs iodine while sandwiching and stretching polyvinyl alcohol is sandwiched between cellulose acetate protective films. The polarizing plate which consists of itself can be mentioned.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.
Various measurements in Examples and Comparative Examples were performed by the following methods.
(1) Liquid crystal orientation The presence or absence of an abnormal domain when a voltage is turned on / off (applied / released) to a liquid crystal display element using the obtained coating film as a liquid crystal alignment film is observed with a polarizing microscope. The case where there was not was judged as "good".
(2) Printability evaluation

[Printability evaluation]
A 127 mm (D) × 127 mm (W) × 1.1 mm (H) glass substrate having an ITO film formed on the entire surface of one side is prepared, and the liquid crystal alignment film coating printing is performed on the glass substrate in an environment of 25 ° C. or 35 ° C. The liquid crystal aligning agent obtained in the above experiment was filtered with a microfilter having a pore diameter of 0.2 μm using a machine (Nissha Printing Co., Ltd. Angstromer S-40L), and then applied to the transparent electrode surface. It dried with the hotplate close contact type preliminary dryer set to 80 degreeC, and baked for 60 minutes at 200 degreeC, and formed the liquid crystal aligning film on the glass substrate with an ITO film | membrane. The number of repels was evaluated by examining the number of repels printed in the center 10 cm ² of the obtained film.

[Evaluation of uniformity of coating film printed with liquid crystal aligning agent]
Using a stylus type film thickness meter, the average film thickness of the coating film and the difference (variation) between the maximum film thickness and the minimum film thickness were measured.

Synthesis Example 1 (Synthesis of polymer)
As tetracarboxylic dianhydride, 2,2.4 g (0.1 mol) of 2,3,5-tricarboxycyclopentylacetic acid dianhydride, and 19.8 g (0.1 mol) of 4,4′-diaminodiphenylmethane as a diamine compound Was dissolved in 800 g of N-methyl-2-pyrrolidone and reacted at 60 ° C. for 4 hours. The reaction solution was then poured into a large excess of methyl alcohol to precipitate the reaction product. Thereafter, it was washed with methyl alcohol and dried at 40 ° C. under reduced pressure for 15 hours to obtain 390 g of polyamic acid having a logarithmic viscosity of 0.32 dl / g. 25 g of the obtained polyamic acid was dissolved in 475 g of N-methyl-2-pyrrolidone, 39.5 g of pyridine and 30.6 g of acetic anhydride were added, and dehydration and ring closure were performed at 110 ° C. for 4 hours. The pressure was reduced to obtain 19.5 g of polyimide (A-1) having a logarithmic viscosity of 0.64 dl / g and an imidization rate of 92%.

Synthesis Example 2 (Synthesis of polymer)
In Synthesis Example 1, a polyamic acid was obtained in the same manner as in Synthesis Example 1 except that 10.8 g (0.1 mol) of p-phenylenediamine was used as the diamine compound. The imidization reaction was performed to obtain 17.9 g of polyimide (A-2) having a logarithmic viscosity of 0.77 dl / g and an imidization ratio of 93%.

Synthesis Example 3 (Synthesis of polymer)
As tetracarboxylic dianhydride, 2,2.4 g (0.1 mol) of 2,3,5-tricarboxycyclopentylacetic acid dianhydride, and 19.8 g (0.1 mol) of 4,4′-diaminodiphenylmethane as a diamine compound Was dissolved in 800 g of N-methyl-2-pyrrolidone and reacted at 60 ° C. for 4 hours. The reaction solution was then poured into a large excess of methyl alcohol to precipitate the reaction product. Thereafter, it was washed with methyl alcohol and dried at 40 ° C. under reduced pressure for 15 hours to obtain 390 g of polyamic acid having a logarithmic viscosity of 0.32 dl / g. 25 g of the obtained polyamic acid was dissolved in 475 g of N-methyl-2-pyrrolidone, 15.8 g of pyridine and 20.4 g of acetic anhydride were added, dehydration and ring closure were performed at 110 ° C. for 4 hours, and precipitation, washing, The pressure was reduced to obtain 18.5 g of polyimide (A-3) having a logarithmic viscosity of 0.40 dl / g and an imidization rate of 81%.

Synthesis Example 4 (Synthesis of polymer)
In Synthesis Example 1, a polyamic acid was obtained in the same manner as in Synthesis Example 1 except that 10.8 g (0.1 mol) of p-phenylenediamine was used as the diamine compound. The imidization reaction was carried out to obtain 16.8 g of polyimide (A-4) having a logarithmic viscosity of 0.43 dl / g and an imidization ratio of 83%.

Synthesis Example 5 (Synthesis of polymer)
In Synthesis Example 1, a polyamic acid was obtained in the same manner as in Synthesis Example 1, except that 21.2 g (0.1 mol) of 2,2′-dimethyl-4,4′-diaminobiphenyl was used as the diamine compound. Using this, imidation reaction was performed in the same manner as in Synthesis Example 1 to obtain 16.8 g of polyimide (A-5) having a logarithmic viscosity of 0.43 dl / g and an imidization ratio of 83%.

Synthesis Example 6 (Synthesis of polymer)
In Synthesis Example 1, the same procedure as in Synthesis Example 1 was conducted, except that 5.4 g (0.05 mol) of p-phenylenediamine and 9.9 g (0.05 mol) of 4,4′-diaminodiphenylmethane were used as the diamine compound. Thus, a polyamic acid was obtained, and an imidization reaction was carried out in the same manner as in Synthesis Example 1 to obtain 18.0 g of polyimide (A-6) having a logarithmic viscosity of 0.24 dl / g and an imidization rate of 81%. .

Synthesis Example 7 (Synthesis of polymer)
In Synthesis Example 1, a polyamic acid was obtained in the same manner as in Synthesis Example 1 except that 20.0 g (0.1 mol) of 4,4′-diaminodiphenyl ether was used as the diamine compound. Similarly, imidization reaction was performed to obtain 19.6 g of polyimide (A-7) having a logarithmic viscosity of 0.25 dl / g and an imidization ratio of 80%.

Synthesis Example 8 (Synthesis of polymer)
In Synthesis Example 1, 2,3,5-tricarboxycyclopentylacetic acid dianhydride 16.8 g (0.075 mol) and pyromellitic dianhydride 5.5 g (0.025 mol) as tetracarboxylic dianhydrides A polyamic acid was obtained in the same manner as in Synthesis Example 1 except that was used, and an imidization reaction was carried out in the same manner as in Synthesis Example 1 using this. (A-8) 19.1 g was obtained.

Examples 1-8
The specific polymers obtained in Synthesis Examples 1 to 8 were dissolved in a solvent having the composition shown in Table 1, and N-ethoxycarbonyl-3-aminopropyltriethoxysilane was added to 0.75 weight with respect to 100 weight parts of the polymer. Partly dissolved to give a solution having a solid content concentration of 4% by weight. This solution was filtered using a filter having a pore diameter of 1 μm to prepare a film forming composition of the present invention.
Next, the film-forming composition is applied onto a transparent conductive film made of an ITO film provided in a comb-teeth shape on one surface of a glass substrate having a thickness of 1 mm using a spinner, and is placed on a hot plate at 230 ° C. for 10 minutes. By drying, a resin film having a film thickness of about 800 Å was formed.

The formed resin film surface was rubbed using a rubbing machine having a roll around which a nylon cloth was wound to obtain a liquid crystal alignment film. Here, the rubbing treatment conditions were a roll rotation speed of 1000 rpm, a stage moving speed of 25 mm / second, and a hair foot pushing length of 0.4 mm. (This substrate is called “substrate A”.)
Similarly, the film-forming composition was applied on one surface of a 1 mm thick glass substrate by a spinner and dried on a hot plate at 230 ° C. for 10 minutes to form a resin film having a thickness of about 800 Å. .

The formed resin film surface was rubbed using a rubbing machine having a roll around which a nylon cloth was wound to obtain a liquid crystal alignment film. Here, the rubbing treatment conditions were a roll rotation speed of 1000 rpm, a stage moving speed of 25 mm / second, and a hair foot pushing length of 0.4 mm. (This substrate is called “Substrate B”.)
Next, an epoxy resin adhesive containing aluminum oxide spheres having a diameter of 5.5 μm was applied to the outer edges of the substrate A and the substrate B having the liquid crystal alignment film of the liquid crystal sandwiched substrate subjected to the rubbing treatment, and then the rubbing in each liquid crystal alignment film The two substrates were placed opposite each other with a gap so that the directions were anti-parallel, and the outer edge portions were brought into contact with each other and pressed to cure the adhesive. Next, a nematic liquid crystal (MLC-2042, manufactured by Merck & Co., Inc.) is filled between the pair of substrates from the liquid crystal injection port, and then the liquid crystal injection port is sealed with an acrylic photo-curing adhesive. The polarizing plate was bonded together to produce the transverse electric field type liquid crystal display element of the present invention, and the orientation was evaluated. The results are shown in Table 1.

  The specific polymers obtained in Synthesis Examples 1 to 8 were dissolved in solvents having various compositions shown in Table 1, and N-ethoxycarbonyl-3-aminopropyltriethoxysilane was added to 0.75 parts by weight based on 100 parts by weight of the polymer. A part by weight was dissolved to obtain a solution having a solid content concentration of 4% by weight. This solution was filtered using a filter having a pore diameter of 1 μm to prepare a film forming composition of the present invention. A coating film was formed using this film-forming composition and evaluated for printability. The results are also shown in Table 1.

Examples 9-16
The specific polymers obtained in Synthesis Examples 1 to 8 are dissolved in a solvent having the composition shown in Table 1, and N, N, N ′, N′-tetraglycidyl-4,4′-diaminodiphenylmethane is used as an epoxy-based additive. A lateral electric field type liquid crystal display device was produced and a coating film was formed in the same manner as in Example 1 except that 5 parts by weight (molecular weight of about 400) was dissolved with respect to 100 parts by weight of the polymer. And printability were evaluated. The results are shown in Table 2.

Reference Examples 1-8
The specific polymers obtained in Synthesis Examples 1 to 8 were dissolved in a solvent having the composition shown in Table 1, and N-ethoxycarbonyl-3-aminopropyltriethoxysilane was added to 0.75 weight with respect to 100 weight parts of the polymer. Partly dissolved to give a solution having a solid content concentration of 4% by weight. This solution was filtered using a filter having a pore diameter of 1 μm to prepare a film forming composition of the present invention. A coating film was formed using this film-forming composition, and the orientation and printability were evaluated in the same manner as in Examples 1 and 2. The results are shown in Table 1.

The types of solvents in Table 1 are as follows.
(A) γ-butyrolactone (b) N-methyl-2-pyrrolidone (c) 3-butoxy-N, N-dimethylpropanamide (d) butyl cellosolve

Claims (5)

The following formula (1) obtained by dehydrating and cyclizing a polyamic acid obtained by reacting tetracarboxylic dianhydride and diamine

Where R ¹ is a tetravalent organic group and R ² is a divalent organic group.
A liquid crystal aligning agent for a horizontal electric field mode liquid crystal display element, comprising a soluble polyimide having an imide structure represented by the formula: wherein the soluble polyimide has an imidization ratio of 60 to 95%. The liquid crystal aligning agent for a horizontal electric field mode liquid crystal display device according to claim 1, wherein the tetracarboxylic dianhydride is 2,3,5-tricarboxycyclopentylacetic acid dianhydride. The tetracarboxylic dianhydride is composed of two or more types of tetracarboxylic dianhydrides, and one of them, 2,3,5-tricarboxycyclopentylacetic acid dianhydride, is the total amount of tetracarboxylic dianhydrides. The liquid crystal aligning agent for horizontal electric field system liquid crystal display elements of Claim 1 which occupies 20 weight% or more. The diamine is p-phenylenediamine, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenyl ether, 2,2-bis [4- (4-aminophenoxy) phenyl] propane and 2,2′-dimethyl-4, The liquid crystal aligning agent for a horizontal electric field mode liquid crystal display element according to claim 1, which is at least one diamine selected from the group consisting of 4'-diaminobiphenyl. A transverse electric field type liquid crystal display device comprising a liquid crystal alignment film obtained from the liquid crystal alignment agent according to claim 1.