JP2006017880A - Liquid crystal aligning agent and in-plane switching mode system liquid crystal display element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a horizontal liquid crystal display element superior in residual image relaxing characteristics and a liquid crystal aligning agent therefor. <P>SOLUTION: The liquid crystal aligning agent for a horizontal electric field system liquid crystal display element contains a soluble polyimide, having an imide structure obtained by cyclodehydrating a polyamic acid prepared by making tetracarboxylic acid dianhydride react with diamine. <P>COPYRIGHT: (C)2006,JPO&NCIPI

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 polymer having a structure obtained by dehydrating and ring-closing the polyamic acid, for example, a photo-alignment film proposed in Patent Document 1 or proposed in Patent Document 2 or Patent Document 3 When a transverse electric field type liquid crystal display element is produced using the polyamic acid that has been prepared, an afterimage is generated. Although this afterimage disappears after a certain amount of time has elapsed, it is a problem that is said to be a big fatal point for a liquid crystal display element, particularly for a liquid crystal display of 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 having excellent afterimage relaxation characteristics.

  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.
A liquid crystal aligning agent for a horizontal electric field mode liquid crystal display element containing a soluble polyimide having an imide structure represented by the formula: wherein the soluble polyimide has an imidization ratio of 60 to 95%, and contains the soluble polyimide This is achieved by a liquid crystal aligning agent for a horizontal electric field mode liquid crystal display element, characterized in that the rate is 60% or more based on the total polyimide.

  Further, according to the present invention, the above object and advantage of the present invention are secondly provided with a liquid crystal alignment film obtained from the liquid crystal aligning agent of the present invention. Achieved by:

  As one of the problems in the horizontal electric field type liquid crystal display element, the afterimage generation during long-time driving causes the quality of the display element to deteriorate. According to the liquid crystal aligning agent of this invention, when it is set as a liquid crystal aligning film, it is excellent in an afterimage relaxation characteristic, Therefore 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 a desk calculator, a wristwatch, a table clock, a counting display board, a word processor, a personal computer, a mobile phone, and a liquid crystal television.

  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. The polyamic acid obtained by reacting in a solvent can be obtained by partial dehydration cyclization, that is, the polyamic acid is a soluble polyimide having an imidation ratio of 60 to 95%. A resin solution obtained by dissolving this soluble polyimide and another polyimide in an organic polar solvent is applied to 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. As a result, a polyimide 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 mode liquid crystal display element, afterimage generation is generally a problem in driving by applying an electric field for a long time. However, since the liquid crystal aligning agent of the present invention has good afterimage relaxation characteristics, the horizontal electric field mode liquid crystal Excellent display performance can be imparted as a display element.

  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, and the like 2,3,5 carboxymethyl alicyclic such as cyclopentyl acetic dianhydride tetracarboxylic dianhydride. Of these, 2,3,5-tricarboxycyclopentylacetic acid dianhydride and 1,2,3,4-cyclobutanetetracarboxylic dianhydride are particularly preferred.

  These tetracarboxylic dianhydrides may be used alone or in admixture of two or more. 2,3,5-Tricarboxycyclopentylacetic acid dianhydride is used alone as tetracarboxylic dianhydride or it is preferably 20% by weight or more, more preferably 50% by weight or more and other tetracarboxylic dianhydrides. It is preferable to use it as a mixture with a product.

  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, aprotic polar solvents such as 1-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, dimethyl sulfoxide, γ-butyrolactone, tetramethylurea, hexamethylphosphortriamide; m-cresol And phenolic solvents such as xylenol, phenol, and halogenated phenol. 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, alcohols, ketones, esters, ethers, halogenated hydrocarbons, hydrocarbons, etc., which are poor solvents for polyamic acid, are used in combination with the organic solvent as long as the resulting polyamic acid does not precipitate. be able to. Specific examples of such a poor solvent include, for example, methyl alcohol, ethyl alcohol, isopropyl alcohol, cyclohexanol, 4-hydroxy-4-methyl-2-pentanone, ethylene glycol, propylene glycol, 1,4-butanediol, and 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, Diethyl malonate, 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. A preferable imidation ratio is 60 to 95%, and more 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 a 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. ).

[Other polyimides]
In the present invention, other polyimides can be used in addition to the soluble polyimide. Other polyimides are polyimides that are hardly soluble in organic solvents. In the liquid crystal aligning agent, it is preferable that polyimide is dissolved in an organic solvent, and therefore other polyimides are required to be 40% or less of the total polyimide.

  The tetracarboxylic dianhydride and diamine used for the synthesis of other polyimides can be those used for the synthesis of soluble polyimides. Moreover, the synthesis | combination of another polyimide can also be performed by the same method.

[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 Examples include ether, diethylene glycol diethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether acetate, and diethylene glycol monoethyl ether acetate.

  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-4,4 ′ Diaminodiphenylmethane, 3- (N-allyl--N- glycidyl) 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, a glass such as float glass or soda glass; a transparent substrate made of a plastic such as polyethylene terephthalate, polybutylene terephthalate, polyethersulfone, or polycarbonate can be used. As the 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 that 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) Afterimage relaxation measurement This occurs when the liquid crystal display element is driven with a triangular wave of 30 VAC and 10 Hz for 3 hours in a high temperature environment (60 ° C.), and then the driving condition is changed to a rectangular wave of 10 VAC and 10 Hz at room temperature. Evaluation was made by measuring the time until the afterimage brightness disappeared in 1 second increments.

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 to obtain a polyimide having a logarithmic viscosity of 0.28 dl / g and an imidization rate of 81%. (A-8) 19.1 g was obtained.

Synthesis Example 9 (Synthesis of polymer)
As tetracarboxylic dianhydride, 7.2 g (0.0375 mol) of pyromellitic dianhydride and 8.0 g (0.0375 mol) of cyclobutanetetracarboxylic dianhydride, and 4,4′-diamino as a diamine compound. 14.8 g (0.075 mol) of diphenylmethane was dissolved in 170 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 21.5 g of polyamic acid (B-1) having a logarithmic viscosity of 0.16 dl / g.

Synthesis Example 10
Other than using 22.4 g (0.1 mol) of 2,3,5-tricarboxycyclopentylacetic acid dianhydride as the acid anhydride and 19.8 g (0.1 mol) of 4,4′-diaminodiphenylmethane as the diamine compound In the same manner as in Synthesis Example 7, 21.4 g of polyamic acid (B-2) having a logarithmic viscosity of 0.35 dl / g was obtained.

Synthesis Example 11 (Synthesis of polymer)
In Synthesis Example 1, 27.4 g (0.14 mol) of cyclobutanetetracarboxylic dianhydride as the acid dianhydride and 32.5 g (0. 2 of 2,2′-dimethyl-4,4′-diaminobiphenyl as the diamine compound). 14 mol) was used in the same manner as in Synthesis Example 7 to obtain 22.1 g of polyamic acid (B-3) having a logarithmic viscosity of 0.24 dl / g.

Example 1
The polyimide (A-1) obtained in Synthesis Example 1 was dissolved in γ-butyrolactone, and 0.75 part by weight of N-ethoxycarbonyl-3-aminopropyltriethoxysilane was dissolved with respect to 100 parts by weight of the polymer. A solution having a solid content concentration of 4% by weight was obtained. 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 thickness of 800 angstroms 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 to one surface of a glass substrate having a thickness of 1 mm by a spinner and dried on a hot plate at 230 ° C. for 10 minutes to form a resin film having a thickness of 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. A polarizing plate was laminated to produce a transverse electric field type liquid crystal display element of the present invention.

  When the obtained liquid crystal display element was evaluated, the orientation was good, and in general, no stains or irregularities were observed despite the strong rubbing conditions. Moreover, afterimage relaxation evaluation was performed using these liquid crystal display elements. In this evaluation, Table 1 shows the results of evaluation with a residual image relaxation time of 1 second or less as ◯ and those with a residual image exceeding 1 second as x.

Example 2
A coating film was formed and a liquid crystal display device was prepared in the same manner as in Example 1 except that the polymers listed in Table 1 were used, and various evaluations were performed using this. The results are also shown in Table 1.

Examples 3-8
A coating film was formed and a liquid crystal display device was prepared in the same manner as in Example 1 except that the polymer described in Table 1 was dissolved in γ-butyrolactone to obtain a solution having a solid concentration of 4% by weight. Various evaluations were performed using this. The results are also shown in Table 1.

Examples 9-11
N, N, N ′, N′-tetraglycidyl-4,4′-diaminodiphenylmethane (molecular weight of about 400) was used as an epoxy-based additive in preparing a film-forming composition using the polymers listed in Table 1. A coating film was formed and a liquid crystal display device was prepared in the same manner as in Example 1 except that 5 parts by weight of the polymer was dissolved in the polymer 100, and various evaluations were performed using this. The results are also shown in Table 1.

Comparative Examples 1-3
A coating film was formed and a liquid crystal display device was prepared in the same manner as in Example 1 except that the polymer described in Table 1 was dissolved in γ-butyrolactone to obtain a solution having a solid concentration of 4% by weight. Various evaluations were performed using this. The results are also shown in Table 1.

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 containing a soluble polyimide having an imide structure represented by the formula: wherein the soluble polyimide has an imidization ratio of 60 to 95%, and contains the soluble polyimide A liquid crystal aligning agent for a horizontal electric field mode liquid crystal display element, wherein the ratio is 60% or more based on the total polyimide. 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. Tetracarboxylic dianhydride is composed of two or more kinds of tetracarboxylic dianhydrides and 2,3,5-tricarboxycyclopentylacetic dianhydride accounts for 20% by weight or more of the total amount of tetracarboxylic dianhydrides The liquid crystal aligning agent for horizontal electric field type liquid crystal display elements of Claim 1. The diamine component 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, comprising at least one diamine compound selected from the group consisting of 4,4′-diaminobiphenyl. A lateral electric field type liquid crystal display element comprising a liquid crystal alignment film obtained from the liquid crystal alignment agent according to claim 1.