KR101778092B1 - Liquid crystal alignment film, method for forming the liquid crystal alignment film, and liquid crystal display device - Google Patents

Abstract

An object of the present invention is to provide a liquid crystal aligning agent capable of forming a liquid crystal alignment film having excellent performances such as good liquid crystal alignability and electrical characteristics by an optical alignment method with excellent radiation sensitivity and a low irradiation dose . It is also intended to provide a method for forming a liquid crystal alignment film using the same, a liquid crystal alignment film, and a liquid crystal display device having the same.
(Solution) A liquid crystal aligning agent containing a polyamic acid and / or a polyimide having a bicyclo [2.2.2] octene skeleton. The polyamic acid is a liquid crystal aligning agent having a structural unit represented by the following formula (1), and the polyimide has a structural unit represented by the following formula (2).

Description

TECHNICAL FIELD [0001] The present invention relates to a liquid crystal alignment film, a method of forming a liquid crystal alignment film, and a liquid crystal display device,

The present invention relates to a liquid crystal aligning agent, a liquid crystal alignment film, a method for forming a liquid crystal alignment film, and a liquid crystal display device which are suitable for photo alignment.

BACKGROUND ART Liquid crystal displays (LCDs) are widely used in televisions and various monitors. As display elements of LCDs, electrode structures of TN (Twisted Nematic) type, STN (Super Twisted Nematic) type, IPS (In Plane Switching) type and IPS type are changed and the aperture ratio of the display element part is increased to improve the brightness And FFS (Fringe Field Switching) type liquid crystal cells (see Patent Documents 1 and 2).

As a method of orienting the liquid crystal of such a liquid crystal cell, there are a method of forming an organic film such as a liquid crystal alignment film on the substrate surface and rubbing the organic film surface with a cloth such as rayon in one direction, A method of forming a single molecular film having a long chain alkyl group using a Langmuir-Blodgett method (LB method), and the like are known. Among them, the rubbing process is the most common method in view of the substrate size, alignment uniformity of the liquid crystal, processing time, and processing cost.

However, when the alignment of the liquid crystal is performed by the rubbing treatment, dust may be adhered to the surface of the alignment film due to generation of dust in the process or generation of static electricity, which may cause display defects. Particularly, in the case of a substrate having a TFT (Thin Film Transistor) element, circuit breakage of the TFT element occurs due to the generated static electricity, which may cause a decrease in yield. Further, in a liquid crystal display element which is further finer in the future, irregularities are generated on the surface of the substrate with the increase in the density of pixels, so that it becomes difficult to uniformly perform the rubbing treatment.

As a means for avoiding the above problem, there has been proposed an optical alignment method (refer to Patent Documents 3 and 4) in which a photosensitive thin film such as polyvinyl cinnamate is irradiated with polarized light or non-polarized radiation to give a liquid crystal aligning ability, And a liquid crystal alignment treatment method using a polyimide resin as a material of the photosensitive thin film (see Patent Document 5). According to this method, uniform liquid crystal alignment can be realized without generating static electricity or dust. Further, the direction of liquid crystal alignment can be controlled in arbitrary direction and precisely compared to the rubbing treatment. Further, a plurality of regions having different liquid crystal alignment directions can be arbitrarily formed on one substrate by using a photomask or the like in the irradiation of radiation.

However, there is a problem that heating is required at the time of irradiating the radiation, or a large integral exposure dose is required. Further, according to the conventional liquid crystal alignment treatment method using a polyimide resin, heating at the time of irradiation with radiation is not necessary, but there is a problem that the sensitivity is insufficient.

Taking this situation into consideration, it is possible to form a liquid crystal alignment film having good liquid crystal alignability by a photo-alignment method with a low irradiation amount, and to form a liquid crystal display element having various performances such as excellent electrical characteristics It is strongly desired to develop a liquid crystal aligning agent capable of forming a liquid crystal alignment layer. Also, there is a strong demand for a method of forming a liquid crystal alignment film using the same, and a liquid crystal alignment film, and further, a liquid crystal display device having the same.

Japanese Laid-Open Patent Publication No. 56-91277 Japanese Unexamined Patent Application Publication No. 1-120528 Japanese Patent Application Laid-Open No. 6-287453 Japanese Patent Application Laid-Open No. 2003-307736 Japanese Patent Application Laid-Open No. 9-297313

An object of the present invention is to provide a liquid crystal aligning agent capable of forming a liquid crystal alignment film having excellent radiation sensitivity and good liquid crystal alignability by a photo-alignment method with a low irradiation dose. It is another object of the present invention to provide a method for forming a liquid crystal alignment film using such a liquid crystal aligning agent and a liquid crystal alignment film, and further to provide a liquid crystal display device having excellent performance such as electrical characteristics in addition to liquid crystal alignability.

The invention made to solve the above problems is a liquid crystal aligning agent containing a polyamic acid and / or a polyimide having a bicyclo [2.2.2] octene skeleton.

Since the liquid crystal aligning agent of the present invention contains a polyamic acid and / or a polyimide having a bicyclo [2.2.2] octene skeleton, the radiation sensitivity becomes high, and therefore a liquid crystal alignment film having good liquid crystal alignability can be formed . Further, the reason why the radiation sensitivity is increased by containing a polyamic acid and / or a polyimide having a bicyclo [2.2.2] octene skeleton is not necessarily clear, but is presumed as follows. Due to the decomposition of the main chain such as a polyamic acid or the dimerization due to bonding between the main chains due to the Diels-Alder reaction due to the presence of the bicyclo [2.2.2] octene skeleton in the polyamic acid or the like , It is conceivable that the light is magnified by the polarization. In this case, the part where the decomposition reaction or the bonding reaction takes place is three-dimensionally complex as compared with, for example, a polyamic acid having a cyclobutane skeleton, so that the structural change of the polymer before and after the reaction becomes larger. As a result, it is conceivable that the light distribution can be reduced to a smaller irradiation amount. As described above, since the amount of radiation required for light alignment can be reduced, the liquid crystal aligning agent can realize the cost reduction. Further, since the liquid crystal aligning agent does not require a heating step during and after irradiation, a liquid crystal alignment film can be produced efficiently. Further, when a liquid crystal alignment film formed by the liquid crystal aligning agent is used, a liquid crystal display device excellent in performance such as electrical characteristics can be produced.

It is preferable that the polyamic acid has a structural unit represented by the following formula (1), and the polyimide has a structural unit represented by the following formula (2).

(In the formulas (1) and (2), R ¹ and R ² are each independently a divalent organic group).

With respect to the liquid crystal aligning agent, the polyamic acid and the polyimide have the specific structure described above, so that the liquid crystal aligning agent can have a higher sensitivity of photo-alignment property.

The liquid crystal aligning agent of the present invention is suitably used for photo alignment. The liquid crystal aligning agent can form a liquid crystal alignment film having a high sensitivity to radiation and an excellent liquid crystal aligning ability by radiation of a low irradiation dose.

The method for forming a liquid crystal alignment film of the present invention comprises:

(1) a step of applying the liquid crystal aligning agent of the present invention on a substrate to form a coating film, and

(2) irradiating the coating film with polarized ultraviolet rays to give liquid crystal alignment capability.

In the forming method of the present invention, it is possible to perform the light distribution by a small amount of irradiation of radiation, and a heating step during and after the irradiation is not necessary. Therefore, the liquid crystal alignment film can be efficiently produced, and the productivity is high, contributing to the reduction of the manufacturing cost.

The present invention suitably includes a liquid crystal alignment film formed by the liquid crystal aligning agent. Since the liquid crystal alignment film of the present invention is formed by the liquid crystal aligning agent, the sensitivity to radiation is high and the liquid crystal aligning ability can be imparted by radiation of a low irradiation amount in the process of forming the liquid crystal alignment film. Further, since the heating step during and after the irradiation of radiation is not necessary, the production efficiency is good and the manufacturing cost can be reduced.

The liquid crystal display element of the present invention comprises the liquid crystal alignment film. Since the liquid crystal alignment film is formed of the liquid crystal aligning agent of the present invention, it is possible to impart a liquid crystal aligning ability with a smaller dose of radiation than in the prior art. Therefore, the liquid crystal display device having the liquid crystal alignment film can be manufactured at a lower cost than the conventional one. Further, the liquid crystal display element of the present invention sufficiently maintains the performance such as electrical characteristics.

The term " light " in the " optical alignment " used in the present specification is a concept including visible light, ultraviolet light, far ultraviolet light, X-ray and charged particle light. The term " radiation " is a concept including the above-mentioned " light " in addition to an electron beam and a particle beam.

The liquid crystal aligning agent of the present invention can form a liquid crystal alignment film having excellent liquid crystal alignability by radiation irradiation with a high radiation sensitivity and a low irradiation amount. In addition, since a heating step during and after the irradiation of radiation is not necessary, the production efficiency is good when the liquid crystal alignment film is produced, and further, the production cost can be reduced. In addition, the liquid crystal display device comprising the liquid crystal alignment film formed using the liquid crystal aligning agent of the present invention is also excellent in performance such as electrical characteristics.

(Mode for carrying out the invention)

<Liquid Crystal Aligner>

The liquid crystal aligning agent of the present invention contains a polyamic acid and / or a polyimide having a bicyclo [2.2.2] octene skeleton. A radiation sensitivity containing a polyamic acid and / or a polyimide having a bicyclo [2.2.2] octene skeleton is improved, and a liquid crystal alignment film having excellent liquid crystal alignability can be formed with low irradiation dose. Further, the liquid crystal display device having this liquid crystal alignment film is also excellent in performance such as electrical characteristics. The liquid crystal aligning agent of the present invention may contain other components in addition to the above-mentioned polyamic acid and / or polyimide as essential components, so long as the effect of the present invention is not impaired. Each will be described in detail below.

[Polyamic acid]

The polyamic acid used in the present invention has a bicyclo [2.2.2] octene skeleton. The polyamic acid is not particularly limited as long as it is a polyamic acid having a bicyclo [2.2.2] octene skeleton in its structure. Such a polyamic acid is, for example, tetracarboxylic acid dianhydride having a bicyclo [2.2.2] octene skeleton And a diamine compound in an organic solvent.

Examples of the tetracarboxylic acid dianhydride having a bicyclo [2.2.2] octene skeleton include bicyclo [2.2.2] oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, 7 -Methyl-bicyclo [2.2.2] oct-7-ene-2,3,5,6-tetracarboxylic acid dianhydride, 7-ethyl-bicyclo [2.2.2] oct- Tetracyanoic acid dianhydride, 7-n-propyl-bicyclo [2.2.2] octo-7-ene-2,3,5,6-tetracarboxylic acid dianhydride, 7-ene-2,3,5,6-tetracarboxylic dianhydride, 7-sec-butyl-bicyclo [2.2.2] oct- Tetracarboxylic dianhydride, 1-methyl-bicyclo [2.2.2] oct-7-ene-2,3,5,6-tetracarboxylic acid dianhydride, Cyclo [2.2.2] oct-7-ene-2,3,5,6-tetracarboxylic acid dianhydride, 1-methyl-7-ethyl-bicyclo [ , 5,6-tetracarboxylic acid dianhydride, 1-methyl-7-n-propyl-bicyclo [2.2.2] oct- Methyl-7-n-butyl-bicyclo [2.2.2] octo-7-ene-2,3,5,6-tetracarboxylic dianhydride, 1-methyl-7-sec-butyl- bicyclo [2.2. 2] octo-7-ene-2,3,5,6-tetracarboxylic dianhydride.

Of these, bicyclo [2.2.2] octo-7-ene-2,3,5,6-tetracarboxylic dianhydride, 1-methyl-bicyclo [2.2.2] , 5,6-tetracarboxylic dianhydride, 7-methyl-bicyclo [2.2.2] oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, 2,2,2] octo-7-ene-2,3,5,6-tetracarboxylic dianhydride is preferable, and among these, bicyclo [2.2.2] Tetracarboxylic acid dianhydride, and 7-methyl-bicyclo [2.2.2] oct-7-ene-2,3,5,6-tetracarboxylic dianhydride are more preferable, and bicyclo [2.2 2] octo-7-ene-2,3,5,6-tetracarboxylic dianhydride.

The polyamic acid used in the present invention preferably has a structural unit represented by the above formula (1). By using the polyamic acid having such a specific structure, it becomes possible to orient the liquid crystal molecules in a certain direction with respect to the polarization direction and uniformly and stably by polarized ultraviolet irradiation.

In the formula (1), the divalent organic group represented by R ¹ is a group derived from a diamine compound. Specific examples of the diamine compound are not particularly limited as long as it is a primary diamine generally used in the synthesis of a polyamic acid or a polyimide, and examples thereof include an aliphatic diamine, an alicyclic diamine, an aromatic diamine, and a diaminoorganosiloxane .

Examples of the aliphatic diamine include, for example, meta-xylene diamine, 1,3-propanediamine, tetramethylene diamine, pentamethylene diamine, hexamethylene diamine and the like.

Examples of the alicyclic diamine include 1,4-diaminocyclohexane, 4,4'-methylenebis (cyclohexylamine), and 1,3-bis (aminomethyl) cyclohexane.

Examples of the diaminoorganosiloxane include 1,3-bis (3-aminopropyl) -tetramethyldisiloxane and the like.

Examples of the aromatic diamine include o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, 4,4'-diaminodiphenylmethane, 4,4'- Diaminobiphenyl, 4,4'-diamino-2,2'-bis (trifluoromethyl) biphenyl, 2,7'- Bis (4-aminophenoxy) phenyl] propane, 9,9-bis (4-aminophenyl) fluorene, 2, 4-diaminodiphenyl ether, (4-aminophenoxy) phenyl] hexafluoropropane, 2,2-bis (4-aminophenyl) hexafluoropropane, 4,4 '- (p- phenylenediisopropylidene ) Bisaniline, 4,4'- (m-phenylene diisopropylidene) bisaniline, 1,4-bis (4-aminophenoxy) benzene, 4,4'- , 2,4-diaminopyrimidine, 3,6-diaminoacrylidine, 3,6-diaminocarbazole, N-methyl-3, 6-diaminocarbazole, N, N'-bis (4-aminophenyl) benzidine, N, N'- Aminophenyl) -N, N'-dimethylbenzidine, 1,4-bis- (4-aminophenyl) -piperazine, 3,5- diaminobenzoic acid, dodecaneoxy- Oxy-2,4-diaminobenzene, pentadecanoxy-2,4-diaminobenzene, hexadecaneoxy-2,4-diaminobenzene, octadecanoxy- 2,5-diaminobenzene, pentadecaneoxy-2,5-diaminobenzene, hexadecaneoxy-2,5-diaminobenzene, octadecanoxy-2, 5-diaminobenzene, cholestanyloxy-3,5-diaminobenzene, cholestenyloxy-3,5-diaminobenzene, cholestanyloxy-2,4-diaminobenzene, cholestenyloxy- 2,4-diaminobenzene, 3,5-diaminobenzoic acid cholestanyl, 3,5-diaminobenzoic acid cholesteryl, 3,5-diaminobenzoic acid ranostanyl, (4-aminobenzoyloxy) cholestane, 3,6-bis (4-aminophenoxy) cholestane, 4- (4'-trifluoromethoxybenzoyloxy) cyclohexyl-3,5-diaminobenzoate, Bis (4 - ((aminophenyl) methyl) phenyl) -4-butylcyclohexane, 1 (4'-trifluoromethylbenzoyloxy) cyclohexyl-3,5-diaminobenzoate, Heptylcyclohexane, 1,1-bis (4 - ((aminophenoxy) methyl) phenyl) -4-heptylcyclohexane, Diamino-N, N-diallylaniline, 4-aminobenzylamine, 3-aminobenzylamine, 3-aminobenzylamine, -Aminobenzylamine, 1- (2,4-diaminophenyl) piperazine-4-carboxylic acid, 4- (4-aminophenyl) piperidinyl) propane,? -Amino-? - aminophenyl alkylene, a compound represented by the following formula (A-1), and the like.

(Wherein (A-1) of, X ¹ and X ² are, respectively, a single bond, ^* -O-, ^* -COO- or ^* -OCO- gt; bond hand denominated However, "*" is, X ¹ in combination with a diamino group, and, combined with R ³ in the X ² and; R ³ is a methylene group, an ethylene group or a propylene group, and; a is 0 or 1; b is an integer of 0~2; c Is an integer of 1 to 20, provided that a and b are not 0 at the same time.

The formula (A-1) of, -X ¹ -R ³ -X ² - a 2 As the divalent group, a methylene group, having 2 or 3 represented by an alkylene group, ^* -O-, ^* -COO-, ^* or - is O-CH ₂ CH ₂ -O- are preferred. However, the bonding hands marked with &quot; * &quot; bond with the diaminophenyl group.

Examples of the group represented by -C _c H _{2c +1} in the above formula (A-1) include a methyl group, an ethyl group, a n-propyl group, an n-butyl group, an n-pentyl group, N-heptadecyl, n-heptadecyl, n-heptadecyl, n-pentadecyl, n-pentadecyl, An octadecyl group, an n-nonadecyl group, and an n-eicosyl group.

Further, it is preferable that the two amino groups in the diaminophenyl group are in the 2,4-position or 3,5-position with respect to the other groups.

Examples of the compound represented by the above formula (A-1) include those represented by the following formulas (A-1-1), (A-1-2) and (A-1-3).

As the other diamines, diamines described in JP-A-2010-97188 can be used. In the case of using a diamine represented by the above formula (A-1), a diamine having a long-chain acrylic side chain or a side chain having a cholestanyl skeleton, a liquid crystal aligning agent suitable for a VA (Vertical Alignment) have. Of these dimers, aromatic diamines are preferred.

[Synthesis of polyamic acid]

The polyamic acid used in the present invention is obtained, for example, by reacting a tetracarboxylic acid dianhydride having a bicyclo [2.2.2] octene skeleton with the above diamine compound in an organic solvent.

The content ratio of the tetracarboxylic acid dianhydride having a bicyclo [2.2.2] octene skeleton in the polyamic acid used in the present invention to the diamine-derived aralkyl structural unit is preferably in the range of 0.1 to 100 mol%, more preferably 5 to 95 mol%, and particularly preferably 50 to 90 mol%.

The polyamic acid used in the present invention may be used together with bicyclo [2.2.2] octo-7-ene-2,3,5,6-tetracarboxylic acid dianhydride and other tetracarboxylic dianhydrides. Examples of other tetracarboxylic acid dianhydrides include aliphatic tetracarboxylic dianhydrides, alicyclic tetracarboxylic dianhydrides, and aromatic tetracarboxylic dianhydrides.

Specific examples thereof include aliphatic tetracarboxylic dianhydrides such as butanetetracarboxylic dianhydride;

1,2,3,4-cyclobutane tetracarboxylic acid dianhydride, 2,3,5-tricarboxycyclopentyl acetic acid dianhydride, 1,3,3a, 4,5,9b-hexahydro-5- (tetrahydro Furanyl) -naphtho [l, 2-c] furan-l, 3-dione, 1,3,3a, 4,5,9b-hexahydro- Furan-1, 3-dione, 3-oxabicyclo [3.2.1] octane-2, (Tetrahydrofuran-2 ', 5'-dione), 5- (2,5-diiodotetrahydro-3-furanyl) Hexene-1,2-dicarboxylic anhydride, 3,5,6-tricarboxy-2-carboxymethylnorbornane-2: 3,5: 6-2 anhydride, 2,4,6,8-tetracarboxybicyclo [3.3.0] octane-2,4,6,8-2 anhydride, 4,9-dioxatricyclo [5.3.1.0 ^2,6 ] undecane-3,5,8,10- Tetracarboxylic dianhydride;

Aromatic tetracarboxylic acid dianhydrides such as pyromellitic dianhydride, and tetracarboxylic dianhydrides described in JP-A-2010-97188.

These other tetracarboxylic acid dianhydrides may be used singly or in combination of two or more.

Examples of the organic solvent used for the synthesis of polyamic acid include aprotic polar solvents, phenols and their derivatives, alcohols, ketones, esters, ethers, halogenated hydrocarbons and hydrocarbons.

Specific examples thereof include N, N-dimethylacetamide, N, N-dimethylformamide, dimethylsulfoxide, gamma -butyrolactone, tetramethylurea, hexamethylphosphoric triamide Aprotic polar solvent such as N-methylpyrrolidone;

phenol derivatives such as m-cresol, xylenol, and halogenated phenol;

Alcohols such as methyl alcohol, ethyl alcohol, isopropyl alcohol, cyclohexanol, ethylene glycol, propylene glycol, 1,4-butanediol, triethylene glycol and ethylene glycol monomethyl ether;

Ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone;

Esters such as ethyl lactate, butyl lactate, methyl acetate, ethyl acetate, butyl acetate, methyl methoxypropionate, ethyl ethoxypropionate, diethyl oxalate and 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, Ethers such as ethylene 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 and tetrahydrofuran;

Halogenated hydrocarbons such as dichloromethane, 1,2-dichloroethane, 1,4-dichlorobutane, trichloroethane, chlorobenzene and o-dichlorobenzene;

And hydrocarbons such as hexane, heptane, octane, benzene, toluene, xylene, isoamyl propionate, isoamyl isobutyrate, and diisopentyl ether.

Among these organic solvents, at least one selected from the group consisting of aprotic polar solvents, phenols and derivatives thereof (i), or at least one selected from the organic solvents of the group (i) and at least one selected from the group consisting of alcohols, , An ether, a halogenated hydrocarbon, and a hydrocarbon (ii). In the latter case, the use ratio of the organic solvent in (ii) is preferably 50 mass% or less, more preferably 40 mass% or less, based on the total amount of the organic solvent of (i) and the organic solvent of (ii) And particularly preferably 30% by mass or less.

The amount of the organic solvent used is preferably such that the total amount of the tetracarboxylic acid dianhydride and the diamine is from 0.1 to 50 mass% with respect to the total amount of the reaction solution.

The reaction solution obtained by dissolving the polyamic acid in the above solvent may be directly supplied to the preparation of the liquid crystal aligning agent or the polyamic acid contained in the reaction solution may be isolated and prepared in the preparation of the liquid crystal aligning agent. Alternatively, the polyamic acid isolated may be purified and then supplied to the preparation of the liquid crystal aligning agent. When the polyamic acid is subjected to dehydration cyclization to form polyimide, the reaction solution may be directly supplied to the dehydration ring-closing reaction, or the polyamic acid contained in the reaction solution may be isolated and then subjected to a dehydration ring-closing reaction. Alternatively, the polyamic acid isolated may be purified and then subjected to a dehydration ring-closing reaction. Further, the polyamic acid can be isolated and purified by a known method.

The ratio of the tetracarboxylic acid dianhydride and the diamine to be used in the synthesis reaction of the polyamic acid is preferably such that the amount of the acid anhydride group of the tetracarboxylic acid dianhydride is from 0.2 to 2 equivalents based on 1 equivalent of the amino group of the diamine, Preferably 0.3 to 1.2 equivalents.

The temperature of the synthesis reaction is preferably -20 캜 to 150 캜, more preferably 0 to 100 캜. The time for the synthesis reaction is preferably 0.1 to 24 hours, more preferably 0.5 to 12 hours.

In the synthesis of the polyamic acid, in addition to the tetracarboxylic acid dianhydride and diamine, an endmodified polymer may be synthesized using a suitable molecular weight modifier. By using such a polymer having a terminal modification type, the coating property (printing property) of the liquid crystal aligning agent can be further improved without impairing the effect of the present invention.

Examples of the molecular weight adjuster include acid anhydrides, monoamine compounds, and monoisocyanate compounds.

Examples of the acid anhydride include maleic anhydride, phthalic anhydride, itaconic anhydride, n-decylsuccinic anhydride, n-dodecylsuccinic anhydride, n-tetradecylsuccinic anhydride, and n-hexadecylsuccinic anhydride.

Examples of the monoamine compound include aniline, cyclohexylamine, n-butylamine, n-pentylamine, n-hexylamine, n-heptylamine and n-octylamine.

Examples of the monoisocyanate compound include phenyl isocyanate and naphthyl isocyanate.

The use ratio of the molecular weight regulator is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, based on 100 parts by mass of the total amount of tetracarboxylic acid dianhydride and diamine to be used.

[Polyimide]

The polyimide used in the present invention has a bicyclo [2.2.2] octene skeleton. Is not particularly limited as long as it has a bicyclo [2.2.2] octene skeleton in its structure, but can be obtained, for example, by imidizing a polyamic acid synthesized as described above by dehydration ring closure.

The polyimide used in the present invention preferably has a structural unit represented by the formula (2). By containing the polyimide having such a specific structure, the liquid crystal aligning agent can orient liquid crystal molecules in a certain direction with respect to the polarization direction and uniformly and stably by polarized ultraviolet irradiation.

The polyimide used in the present invention may be a completely imidized product obtained by dehydrating and ring closure of the entire acid structure of the polyamic acid which is a precursor thereof and dehydrating and ring-closure only a part of the acid structure, Partial imide cargo may also be used. The imide ratio of the polyimide in the present invention is preferably 30% or more, more preferably 50 to 99%, and still more preferably 65 to 99%. The imidization rate is a percentage of the ratio of the number of imide ring structures to the sum of the number of amide structure and the number of imide ring structure of polyimide. Here, a part of the imide ring may be an isoimide ring.

[Synthesis of polyimide]

The polyimide used in the present invention can be obtained by dehydrating and cyclizing the polyamic acid synthesized as described above to imidize it.

The dehydration ring-closure of the polyamic acid is preferably carried out by a method of heating the polyamic acid, or a method of dissolving the polyamic acid in an organic solvent, adding a dehydrating agent and a dehydrating ring-closing catalyst to the solution, and optionally heating . The latter method is preferable.

In the method of adding the dehydrating agent and the dehydrating ring-closing catalyst to the solution of the polyamic acid, an acid anhydride such as acetic anhydride, propionic anhydride, or trifluoroacetic anhydride can be used as the dehydrating agent. The amount of the dehydrating agent to be used is preferably 0.01 to 20 mol based on 1 mol of the acid structure of the polyamic acid. As the dehydration ring-closing catalyst, for example, tertiary amines such as pyridine, collidine, lutidine and triethylamine can be used. The amount of the dehydration ring-closing catalyst to be used is preferably 0.01 to 10 mol based on 1 mol of the dehydrating agent to be used. Examples of the organic solvent used in the dehydration ring-closure reaction include the organic solvents exemplified for use in the synthesis of polyamic acid. The reaction temperature of the dehydration ring-closing reaction is preferably 0 to 180 캜, more preferably 10 to 150 캜. The reaction time is preferably 1.0 to 120 hours, more preferably 2.0 to 30 hours.

The reaction solution containing the obtained polyimide may be directly supplied to the preparation of the liquid crystal aligning agent or may be supplied to the preparation of the liquid crystal aligning agent after removing the dehydrating agent and the dehydration cyclization catalyst from the reaction solution, May be added to the preparation of the alignment agent, or may be provided to the preparation of the liquid crystal aligning agent after the isolated polyimide is purified. These purification operations can be carried out according to a known method.

The polyamic acid or polyimide thus obtained preferably has a solution viscosity of 20 to 800 mPa · s and a solution viscosity of 30 to 500 mPa · s Do.

The solution viscosity (mPa 占 퐏) of the polymer is preferably 10% by mass or less, more preferably 10% by mass or less, in terms of a solution prepared using a good solvent (for example,? -Butyrolactone, N-methyl- Polymer solution was measured at 25 占 폚 using an E-type rotational viscometer.

[Other components]

The liquid crystal aligning agent of the present invention contains the aforementioned polyamic acid and / or polyimide as an essential component, but may contain other components as required. Such other components include, for example, other polymers, compounds having at least one epoxy group in the molecule (hereinafter referred to as &quot; epoxy compound &quot;), and functional silane compounds.

(Other polymer)

These other polymers can be used for improvement of solution characteristics and electrical properties. Such another polymer is a polymer other than the polyamic acid or the polyimide described above and is obtained by reacting a tetracarboxylic acid dianhydride other than a tetracarboxylic acid dianhydride having a bicyclo [2.2.2] octene skeleton with a diamine. (Hereinafter also referred to as &quot; other polyimide &quot;), polyamic acid ester, polyester, polyamide, polysiloxane, cellulose derivative (hereinafter also referred to as &quot; other polyimide &quot;) obtained by dehydration cyclization of the polyamic acid , Polyacetal, polystyrene derivatives, poly (styrene-phenylmaleimide) derivatives, and poly (meth) acrylates. Of these, other polyamic acids or other polyimides are preferable, and other polyamic acids are more preferable.

The tetracarboxylic acid dianhydride used for synthesizing the above other polyamic acid or other polyimide may be the same as those described above as the tetracarboxylic acid dianhydride used for synthesizing the polyamic acid used in the present invention, Cyclobutanetetracarboxylic dianhydride, pyromellitic dianhydride, 2,3,5-tricarboxycyclopentyl acetic acid dianhydride and 1,3,3a, 4,5,9b- At least one selected from the group consisting of hexahydro-5- (tetrahydro-2,5-diiod-3-furanyl) -naphtho [1,2-c] furan- .

As the diamine used for synthesizing the above other polyamic acid or other polyimide, it is preferable to use at least one selected from among those exemplified above as the diamine to be used in synthesizing the polyamic acid used in the present invention . Examples of diamines used for synthesizing other polyamic acids or other polyimides include 4,4'-diaminodiphenylmethane, 2,2'-dimethyl-4,4'-diaminobiphenyl, cholestanyloxy-2 , 4-diaminobenzene, 3,5-diaminobenzoic acid and 1,4-bis- (4-aminophenyl) -piperazine are preferably used.

The proportion of other polymers to be used is preferably 50% by mass or less, more preferably 0.1 to 50% by mass, based on the sum of the polymers (the sum of the above-mentioned polyamic acid and / or polyimide and other polymers, By mass to 40% by mass, and more preferably 0.1% by mass to 30% by mass.

(Epoxy compound)

Examples of the epoxy compound 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, 1,6-hexanediol diglycidyl ether, glycerin diglycidyl ether, trimethylol propane triglycidyl ether, 2,2-dibromoneopentyl glycol diglycidyl N, N, N ', N'-bis (N, N-diglycidylaminomethyl) cyclohexane, N'-tetraglycidyl-4,4'-diaminodiphenylmethane, N, N-diglycidyl-benzylamine, N, N-diglycidylaminomethylcyclohexane, N, Glycidyl-cyclohexylamine, and the like.

The mixing ratio of these epoxy compounds is preferably 40 parts by mass or less, more preferably 0.1 to 30 parts by mass, based on 100 parts by mass of the total amount of the polymers.

(Functional silane compound)

Examples of the functional silane compound include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 2-aminopropyltrimethoxysilane, 2-aminopropyltriethoxysilane, N- (2 -Aminoethyl) -3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-ureidopropyltrimethoxysilane, 3-ureidopropyltriethoxy Silane, N-ethoxycarbonyl-3-aminopropyltrimethoxysilane, N-ethoxycarbonyl-3-aminopropyltriethoxysilane, N-triethoxysilylpropyltriethylenetriamine, N- Trimethoxysilyl-1,4,7-triazadecane, 10-triethoxysilyl-1,4,7-triazadecane, 9-trimethoxysilyl-3 , 6-diazanonyl acetate, 9-triethoxysilyl-3,6-diazanonyl acetate, methyl 9-trimethoxysilyl-3,6-diazononanoate, Benzyl-3-aminopropyltrimethoxysilane, N-benzyl-3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane , N-phenyl-3-aminopropyltriethoxysilane, glycidoxymethyltrimethoxysilane, glycidoxymethyltriethoxysilane, 2-glycidoxyethyltrimethoxysilane, 2-glycidoxyethyl tri 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, and the like.

The blending ratio of these functional silane compounds is preferably 2 parts by mass or less, more preferably 0.02 to 0.2 parts by mass based on 100 parts by mass of the total amount of the polymers.

&Lt; Preparation of liquid crystal aligning agent &

The liquid crystal aligning agent of the present invention is constituted by dissolving the above-described polyamic acid or polyimide, and optionally other components optionally blended in an organic solvent.

Examples of the organic solvent used in the liquid crystal aligning agent of the present invention include N-methyl-2-pyrrolidone,? -Butyrolactone,? -Butyrolactam, N, N-dimethylformamide, Methylene-2-pentanone, ethylene glycol monomethyl ether, butyl lactate, butyl acetate, methyl methoxy propionate, ethyl ethoxypropionate, ethylene glycol methyl ether, ethylene Diethylene glycol dimethyl ether, ethylene glycol ethyl ether acetate, diethylene glycol dimethyl ether (ethylene glycol diethyl ether), ethylene glycol n-propyl ether, ethylene glycol-i-propyl ether, ethylene glycol- , Diethylene glycol diethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, di Isobutyl ketone, isoamyl propionate, isoamyl isobutyrate, di-isopentyl ether, ethylene carbonate, propylene carbonate, and the like. These may be used alone or in combination of two or more.

The solid concentration in the liquid crystal aligning agent of the present invention (the ratio of the total mass of components other than the solvent of the liquid crystal aligning agent to the total mass of the liquid crystal aligning agent) is appropriately selected in consideration of viscosity, volatility, etc., Is in the range of 1 to 10% by mass. That is, the liquid crystal aligning agent of the present invention is applied to the surface of the substrate as described later, and preferably, it is heated to form a coating film which becomes a liquid crystal alignment film or a liquid crystal alignment film. When the solid concentration is less than 1 mass% A good liquid crystal alignment film can not be obtained. On the other hand, when the solid concentration exceeds 10% by mass, the film thickness of the film becomes too large to obtain a good liquid crystal alignment film, The viscosity is increased and the coating properties are poor.

A particularly preferable range of the solid concentration is different depending on the method used when the liquid crystal aligning agent is applied to the substrate. For example, in the case of the spinner method, the solid content concentration is particularly preferably in the range of 1.5 to 4.5 mass%. In the case of the printing method, it is particularly preferable that the solid concentration is in the range of 3 to 9 mass% and the solution viscosity is in the range of 12 to 50 mPa 占 퐏. In the case of the ink-jet method, it is particularly preferable that the solid concentration is in the range of 1 to 5 mass%, and the solution viscosity is in the range of 3 to 15 mPa 占 퐏.

The temperature for preparing the liquid crystal aligning agent of the present invention is preferably 10 to 50 占 폚, more preferably 20 to 30 占 폚.

&Lt; Liquid crystal alignment film &

The liquid crystal alignment film of the present invention is formed by the liquid crystal aligning agent. Therefore, in the forming process, it is possible to impart excellent liquid crystal aligning ability by radiation of a low irradiation dose. Further, since the heating step during and after irradiation of radiation is unnecessary, the production efficiency is good and the manufacturing cost can be reduced.

&Lt; Method of forming liquid crystal alignment film &

The liquid crystal aligning agent of the present invention can be suitably used as a material for a liquid crystal alignment film by a photo alignment method. In addition, it can be suitably used for forming a liquid crystal alignment film used in a liquid crystal display device having a TN type or STN type liquid crystal cell, or a liquid crystal display device having a liquid crystal cell such as IPS type or FFS type. The liquid crystal aligning agent of the present invention is preferable because the effect of the present invention is maximized when applied to a liquid crystal display element having a liquid crystal cell of IPS type or FFS type in particular.

The method for forming a liquid crystal alignment film of the present invention comprises:

(1) a step of coating a liquid crystal aligning agent of the present invention on a substrate to form a coating film (hereinafter also referred to as &quot; step (1) &quot;),

(2) a step of irradiating the coating film with polarized ultraviolet rays to give liquid crystal aligning ability (hereinafter, also referred to as step (2)). Each step will be described in detail below.

[Step (1)]

Here, when the liquid crystal aligning agent of the present invention is applied to a liquid crystal display element having a liquid crystal cell of a TN type or STN type, two substrates on which a patterned transparent conductive film is formed are paired, On the film-formed surface, the liquid crystal aligning agent of the present invention is applied to form a coated film. On the other hand, when the liquid crystal aligning agent of the present invention is applied to a liquid crystal display element having liquid crystal cells of the IPS type or FFS type, it is preferable that a substrate having a transparent conductive film or a metal film patterned in a comb- And the liquid crystal aligning agent of the present invention is applied to one surface of the comb-like electrode and one surface of the counter substrate to form a coating film.

In any case, as the above substrate, for example, a transparent substrate made of plastic such as float glass, glass such as soda glass, polyethylene terephthalate, polybutylene terephthalate, polyether sulfone, polycarbonate, or the like can be used. As the transparent conductive film, for example, an ITO film made of In ₂ O ₃ -SnO ₂ , a NESA (registered trademark) film made of SnO ₂ , or the like can be used. As the metal film, for example, a film made of a metal such as chromium can be used. The patterning of the transparent conductive film and the metal film includes, for example, a method of forming a pattern by a photo-etching method or a sputtering method after forming a pattern-free transparent conductive film, a method of using a mask having a desired pattern in forming a transparent conductive film And so on.

Even if a functional silane compound, titanate or the like is previously coated on the substrate and the electrode in order to improve the adhesiveness between the substrate or the conductive film or the electrode and the coating film upon application of the liquid crystal aligning agent onto the substrate good.

The application of the liquid crystal aligning agent onto the substrate can be preferably carried out by an appropriate application method such as offset printing, spin coating, roll coating, inkjet printing, etc., and then the application surface is preheated (prebaked) Followed by baking (post baking) to form a coating film. The prebaking condition is, for example, 0.1 to 5 minutes at 40 to 120 占 폚, and the postbaking condition is preferably 120 to 300 占 폚, more preferably 150 to 250 占 폚, preferably 5 to 200 minutes, Preferably 10 to 100 minutes. The film thickness of the coated film after post baking is preferably 0.001 to 1 mu m, more preferably 0.005 to 0.5 mu m.

[Step (2)]

The coating film thus formed is irradiated with polarized radiation to give a liquid crystal aligning ability. As the radiation, for example, ultraviolet rays and visible rays including light having a wavelength of 150 to 800 nm can be used, but ultraviolet rays including light having a wavelength of 200 to 400 nm are preferable.

As the light source to be used, for example, a low-pressure mercury lamp, a high-pressure mercury lamp, a deuterium lamp, a metal halide lamp, an argon resonance lamp, a xenon lamp, an excimer laser and the like can be used. The ultraviolet ray of the above-mentioned preferable wavelength range can be obtained by a means for using the light source together with a filter, a diffraction grating, or the like.

When the liquid crystal aligning agent of the present invention is used, it is possible to impart a good liquid crystal aligning ability even at a portion requiring 8000 J / m 2 or more of ultraviolet ray irradiation at 10,000 J / m 2 or more, I will contribute.

<Liquid crystal display element>

Since the liquid crystal display element of the present invention is provided with the liquid crystal alignment film formed using the liquid crystal aligning agent, the liquid crystal alignment ability can be imparted with less irradiation dose than the conventional one. Therefore, the liquid crystal display device having the liquid crystal alignment film can be manufactured at a lower cost than the conventional one. The liquid crystal display element of the present invention can be produced, for example, as follows.

A pair of substrates on which a liquid crystal alignment film is formed as described above is prepared, and a liquid crystal cell having a configuration in which liquid crystal is sandwiched between the pair of substrates is manufactured. To produce a liquid crystal cell, for example, the following two methods can be used.

The first method is a conventionally known method. Two substrates are opposed to each other with a space (cell gap) interposed therebetween so that the respective liquid crystal alignment films face each other, and the peripheral portions of the two substrates are bonded together using a sealing agent, and the substrate surface and the cell gap After the liquid crystal is injected and filled, an injection hole is sealed to manufacture a liquid crystal cell.

The second method is a so-called ODF (One Drop Fill) method. For example, an ultraviolet curable sealant is applied to a predetermined place on one of the two substrates on which the liquid crystal alignment film is formed, the liquid crystal is further dropped on the liquid crystal alignment film surface, A liquid crystal cell can be manufactured by bonding one of the substrates and then curing the sealing agent by irradiating ultraviolet light to the entire surface of the substrate.

In either case, it is preferable to heat the liquid crystal cell to a temperature at which the liquid crystal using the liquid crystal has an isotropic phase, and then gradually cool to room temperature to remove the flow alignment at the time of filling the liquid crystal.

The liquid crystal display element of the present invention can be obtained by bonding a polarizing plate to the outer surface of the liquid crystal cell. Here, a desired liquid crystal display element can be obtained by appropriately adjusting the angle formed by the polarization direction of the irradiated linearly polarized radiation and the angle between each substrate and the polarizing plate in the two substrates on which the liquid crystal alignment film is formed.

As the sealing agent, for example, an aluminum oxide spheres as a spacer and an epoxy resin containing a curing agent can be used.

As the liquid crystal, for example, a nematic liquid crystal, a smectic liquid crystal or the like can be used. It is preferable to have a positive dielectric anisotropy for forming a nematic liquid crystal. Examples thereof include biphenyl-based liquid crystals, phenylcyclohexane-based liquid crystals, ester-based liquid crystals, terphenyl-based liquid crystals, Hexane-based liquid crystals, pyrimidine-based liquid crystals, dioxane-based liquid crystals, bicyclooctane-based liquid crystals, quartz-based liquid crystals and the like. Further, it is also possible to add a cholesteric liquid crystal such as cholesteryl chloride, cholesteryl nonanoate or cholesteryl carbonate to the liquid crystal;

Chiral agents such as those sold under the trade names "C-15" and "CB-15" (manufactured by Merck Ltd.);

p-decyloxybenzylidene-p-amino-2-methylbutyl cinnamate, and the like may further be added and used.

As the polarizing plate used for the outside of the liquid crystal cell, there can be mentioned a polarizing plate in which a polarizing film called "H film" in which iodine is absorbed while polyvinyl alcohol is oriented by stretching, a polarizing plate sandwiching a cellulose acetate protective film or a polarizing plate made of H film itself have.

The liquid crystal display element of the present invention thus manufactured is excellent in performance such as display characteristics and electrical characteristics.

(Example)

Hereinafter, the present invention will be described more specifically by way of examples, but the present invention is not limited to these examples.

<Synthesis of polyamic acid>

[Synthesis Example 1]

Bis [4- (4-aminophenoxy) phenyl] bicyclo [2.2.2] octo-7-ene-2,3,5,6-tetracarboxylic acid dianhydride and 0.1 mol 0.1 mol (41.05 g) of propane (D-1) was dissolved in 373.26 g of N-methyl-2-pyrrolidone and reacted at room temperature for 6 hours. The reaction mixture was then mixed with excess methanol and the reaction product was precipitated. Thereafter, the resultant was washed with methanol, and dried at 40 DEG C for 15 hours under reduced pressure to obtain 65 g (yield: 98.7%) of polyamic acid A-1.

[Synthesis Examples 2 to 3]

Polyamic acid polymers A-2 to A-3 were obtained in the same manner as in Synthesis Example 1 except that the diamine compounds were replaced with D-2 to D-3.

[Diamine compound]

D-1: 2,2-bis [4- (4-aminophenoxy) phenyl] propane

D-2: p-phenylenediamine

D-3: 4,4'-diaminodiphenyl ether

[Comparative Synthesis Example 1]

0.1 mole (19.61 g) of 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride and 0.1 mole (41.05 g) of the D-1 compound were dissolved in 343.74 g of N-methyl-2-pyrrolidone, The reaction was allowed to proceed at room temperature for 6 hours. The reaction mixture was then mixed with excess methanol and the reaction product was precipitated. Thereafter, the resultant was washed with methanol, and dried at 40 캜 for 15 hours under reduced pressure to obtain 60 g (yield: 98.9%) of polyamic acid a-1.

[Comparative Synthesis Examples 2 to 3]

The polyamic acid polymers a-2 to a-3 were obtained in the same manner as in Comparative Synthesis Example 1, except that the diamine compounds were changed to D-2 to D-3.

&Lt; Preparation of liquid crystal aligning agent &

[Example 1]

N-methyl-2-pyrrolidone (NMP) and butyl cellosolve (BC) were added to a solution containing the polyamic acid (A-1) obtained in Synthesis Example 1, 20 parts by mass of N, N ', N'-tetraglycidyl-4,4'-diaminodiphenylmethane was added to 100 parts by mass of the total of 100 parts by mass of the polymer, and the mixture was thoroughly stirred to obtain a solvent composition of NMP: BC = (Mass ratio), and a solid content concentration of 2.5 mass%. This solution was filtered using a filter having a pore diameter of 1 탆 to prepare a liquid crystal aligning agent (B-1).

[Examples 2 to 3, Comparative Examples 1 to 3]

Except that polyamic acid A-2 to A-3 and a-1 to a-3 obtained in Synthesis Examples 2 to 3 and Comparative Synthesis Examples 1 to 3 were used instead of A-1 in Example 1 In the same manner as in Example 1, liquid crystal aligning agents B-2 to B-3 and b-1 to b-3 were prepared.

&Lt; Production of liquid crystal display element &

The liquid crystal aligning agents (B-1 to B-3, b-1 to b-3) prepared above were applied onto a transparent electrode surface of a glass substrate with a transparent electrode, each of which was made of an ITO film, , And dried at 200 ° C for 1 hour to form a thin film. The thin film surface was irradiated with 8,000 J / m 2, 10,000 J / m 2 or 50,000 J / m 2 of polarized light containing a 254 nm bright line using a Hg-Xe lamp from the normal direction of the substrate. Next, on the pair of substrates subjected to the light irradiation treatment, an epoxy resin adhesive containing an aluminum oxide sphere having a diameter of 5.5 mu m was applied by screen printing to the surface on which the liquid crystal alignment film was formed, and then the light irradiation direction was anti- , And the adhesive was thermally cured at 150 DEG C for 1 hour. Subsequently, a nematic liquid crystal (ZLI-1565, manufactured by Merck Ltd.) was filled between the pair of substrates from the liquid crystal injection port, and then the liquid crystal injection port was sealed with an epoxy adhesive. Further, in order to remove the flow orientation at the time of injecting the liquid crystal, it was heated at 150 占 폚 and slowly cooled to room temperature. Next, a polarizing plate is arranged on both outer sides of the substrate so that the polarization directions thereof are orthogonal to each other and the direction of projection of the optical axis of the polarized ultraviolet ray of the liquid crystal alignment film to the substrate surface is orthogonal to one side and parallel to the other side So as to produce a liquid crystal display element.

Each of the above liquid crystal display elements was evaluated in the following manner. The results are shown in Table 1.

<Evaluation>

[Liquid crystal alignment property]

In a liquid crystal display element, the presence or absence of an abnormal domain when a voltage was turned on / off (applied / released) was observed with a polarizing microscope, and a case where there is no abnormal domain is "good" Quot; bad &quot;.

[Voltage conservation and maintenance rate]

A voltage of 5 V was applied to the liquid crystal display device manufactured at a polarizing ultraviolet radiation dose of 8,000 J / m 2 at 60 microseconds and 167 milliseconds, and then the voltage storage and maintenance ratio after 167 milliseconds from the application of the voltage was measured. VHR-1 manufactured by Toyo Technica Co., Ltd. was used as a measuring device. The case where the voltage holding and maintaining ratio was 90% or more was judged as &quot; good &quot;, and the cases other than that were judged as &quot; defective &quot;.

As shown in Table 1, the liquid crystal aligning agent containing a polyamic acid of the example having a bicyclo [2.2.2] octene skeleton has a high sensitivity to radiation and a liquid crystal alignment film obtained with a low irradiation dose of 8000 J / The liquid crystal alignability of the liquid crystal display element of the present invention was improved. Also, the voltage retention ratio was good. In contrast, in the comparative example, an abnormal domain was observed at a low irradiation dose of 8000 J / m &lt; 2 &gt;, and the liquid crystal alignability was poor. From the above, it has become clear that the liquid crystal aligning agent of the present invention is excellent in radiation sensitivity and can form a liquid crystal alignment film having excellent liquid crystal alignability in a low irradiation dose of radiation.

The liquid crystal aligning agent of the present invention can form a liquid crystal alignment film and a liquid crystal display device having the liquid crystal alignment film having excellent performance such as good liquid crystal alignability and electrical characteristics by the photo alignment method having excellent radiation sensitivity and low irradiation dose . It is possible to reduce the amount of radiation required for the light alignment, thereby realizing low cost.

Claims (6)

(1) a step of applying a liquid crystal aligning agent on a substrate to form a coating film, and
(2) a step of irradiating the coating film with polarized ultraviolet rays to give liquid crystal aligning ability
The method comprising the steps of:
Wherein the liquid crystal aligning agent is a polyamic acid obtained by reacting a tetracarboxylic acid dianhydride having tetracarboxylic acid dianhydride having a bicyclo [2.2.2] octene skeleton with a diamine compound, and a polyamic acid obtained by dehydration ring closure of the polyamic acid The ratio of the tetracarboxylic acid dianhydride having a bicyclo [2.2.2] octene skeleton and the diamine-derived acid group derived from the diamine in the polyamic acid to the total polymer A method for forming a liquid crystal alignment film in which the ratio is 50 to 100 mol% based on the total structural units. The method according to claim 1,
Wherein the polyamic acid has a structural unit represented by the following formula (1), and the polyimide has a structural unit represented by the following formula (2):

(In the formulas (1) and (2), R ¹ and R ² are each independently a divalent organic group). A liquid crystal alignment film formed by the method according to claim 1 or 2. A liquid crystal display element comprising the liquid crystal alignment film according to claim 3. delete delete