KR101809990B1 - Liquid crystal aligning agent, 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 which has an excellent liquid crystal aligning ability and can increase the voltage holding ratio at the time of using the liquid crystal display element at a high temperature and can reduce thermal deterioration of the voltage holding ratio, And a liquid crystal display element having the liquid crystal alignment film can be provided.
(Solution) The present invention is a liquid crystal aligning agent containing at least one compound selected from the group consisting of a polyamic acid obtained by reacting a tetracarboxylic acid dianhydride with a diamine and an imidized polymer thereof, wherein the tetracarboxylic acid 2 Wherein the anhydride comprises a tetracarboxylic acid dianhydride having an aliphatic hydrocarbon group or an alicyclic hydrocarbon group, and the diamine includes a compound represented by the formula (1).

Description

TECHNICAL FIELD [0001] The present invention relates to a liquid crystal alignment material, 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 and a liquid crystal display element.

In a liquid crystal display element such as a twisted nematic liquid crystal display element (TN mode) and a transverse electric field display type liquid crystal display element (IPS mode), liquid crystal is sealed between a pair of substrates arranged opposite to each other, , And display is performed by a light switching function of modulating light by generating a change in the liquid crystal alignment.

The liquid crystal can be oriented in the processing direction by a process of rubbing the liquid crystal alignment film on the substrate with a long cloth such as rayon or cotton, that is, rubbing treatment. In the horizontal alignment type liquid crystal display device (horizontal alignment mode) such as the TN mode and the IPS mode, a horizontal alignment technique for orienting the liquid crystal in parallel to the substrate surface and the rubbing treatment direction is required.

At present, attempts have been made to use a liquid crystal aligning agent containing an alicyclic polyimide synthesized by using alicyclic tetracarboxylic dianhydride and a diamine compound in the formation of a liquid crystal alignment film suitably used in the horizontal alignment technique. The alicyclic polyimide has less light-induced thermal deterioration because it absorbs less in the visible light region as compared with the aromatic polyimide used in conventional liquid crystal aligning agents, and has less film deterioration during rubbing treatment, (JP-A-57-128318, JP-A-4052308 and JP-A-2010-156934).

On the other hand, liquid crystal display devices, such as car navigation panels and smartphone panels, which are in increasing demand in recent years, are required to be able to be driven in a wider temperature range than conventional liquid crystal display devices. For this reason, liquid crystal display elements are required to have stable display characteristics at high temperatures. However, liquid crystal display devices having a conventional liquid crystal alignment film using the alicyclic polyimide or the like have insufficient voltage retention at the time of high temperature use, There is a problem that thermal deterioration of the voltage holding ratio is large.

Japanese Patent Application Laid-Open No. 57-128318 Japanese Patent No. 4052308 Japanese Laid-Open Patent Publication No. 2010-156934

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is an object of the present invention to provide a liquid crystal aligning agent capable of enhancing a voltage holding ratio at the time of using a liquid crystal display element at a high temperature, A liquid crystal alignment film formed using a liquid crystal aligning agent, and a liquid crystal display element including the liquid crystal alignment film.

According to an aspect of the present invention,

1. A liquid crystal aligning agent containing at least one compound selected from the group consisting of a polyamic acid obtained by reacting a tetracarboxylic dianhydride with a diamine and an imidized polymer thereof,

The tetracarboxylic acid dianhydride includes a tetracarboxylic acid dianhydride (hereinafter also referred to as "aliphatic or alicyclic tetracarboxylic dianhydride") having an aliphatic hydrocarbon group or alicyclic hydrocarbon group,

The liquid crystal aligning agent is characterized in that the diamine includes a compound represented by the following formula (1):

(Wherein X ¹ and X ³ are each independently a single bond, an oxygen atom or a sulfur atom, X ² and X ⁴ are each independently an alkyl group having 1 to 6 carbon atoms, m and n Are independently 0 or 1, provided that both of m and n are not 0).

The liquid crystal aligning agent contains a compound obtained by reacting a polyamic acid or an imidated polymer thereof with an aliphatic or alicyclic tetracarboxylic acid dianhydride and a diamine of the above specific structure so that the voltage holding ratio at the time of using the liquid crystal display element at a high temperature is And the thermal degradation of the voltage holding ratio can be reduced. Further, the liquid crystal aligning agent can be obtained by using, as a diamine, a compound having a substituent at the ortho-position of the amide in the benzene ring as represented by the formula (1) above to give the polyamic acid or its imidized polymer The solubility can be improved.

In the above formula (1), it is preferable that m is 1 and n is 0, or m is 0 and n is 1. As compared with the case where the benzene ring of the diamine represented by the formula (1) has both of X ² -X ¹ - and X ⁴ -X ³ - as a substituent, when an anchoring force .

The tetracarboxylic acid dianhydride having an aliphatic hydrocarbon group or alicyclic hydrocarbon group may be selected from 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride, 2,3,5-tricarboxycyclopentyl acetic acid dianhydride, 1 , 3,3a, 4,5,9b-hexahydro-8-methyl-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [ 3-dione, 1,3,3a, 4,5,9b-hexahydro-5- (tetrahydro-2,5-dioxo-3-furanyl) 3-dione, bicyclo [3,3,0] octane-2,4,6,8-tetracarboxylic acid dianhydride, cyclohexanetetracarboxylic dianhydride, and 1,2,3,4-butanetetracarboxylic acid 2-anhydride. ≪ / RTI >

If the aliphatic or alicyclic tetracarboxylic acid dianhydride is the specific compound described above, the liquid crystal aligning agent can improve the voltage holding ratio at the time of using the liquid crystal display element at a high temperature and reduce thermal deterioration of the voltage holding ratio can do.

The tetracarboxylic acid dianhydride having an aliphatic hydrocarbon group or an alicyclic hydrocarbon group is obtained by reacting 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride, (1S, 2S, 4R, 5R) -cyclohexanetetracarboxylic acid It is preferably at least one compound selected from the group consisting of dianhydrides, (1R, 2S, 4S, 5R) -cyclohexanetetracarboxylic dianhydride and 2,3,5-tricarboxycyclopentyl acetic acid dianhydride .

If the aliphatic or alicyclic tetracarboxylic acid dianhydride is the specific compound described above, the liquid crystal aligning agent can further improve the voltage holding ratio at the time of using the liquid crystal display element at a high temperature, Can be made small.

The tetracarboxylic acid dianhydride may be at least one aromatic compound selected from the group consisting of pyromellitic anhydride, biphenyltetracarboxylic acid dianhydride, naphthalenetetracarboxylic acid dianhydride, and 4,4'-oxydiphthalic anhydride. It is preferable to further include them.

The tetracarboxylic acid dianhydride further includes the specific aromatic compound, so that the orientation property of the liquid crystal aligning agent can be improved.

The tetracarboxylic acid dianhydride preferably further comprises pyromellitic anhydride. As described above, the tetracarboxylic acid dianhydride further contains pyromellitic anhydride, whereby the orientation of the liquid crystal aligning agent can be further improved.

The present invention also includes a liquid crystal alignment film formed by the liquid crystal aligning agent. Since the liquid crystal alignment film is formed of the above-mentioned liquid crystal aligning agent, the voltage holding ratio at the time of using the liquid crystal display element at high temperature can be improved and the thermal deterioration of the voltage holding ratio can be further reduced.

The present invention also includes a liquid crystal display element having the liquid crystal alignment film. Such a liquid crystal display device is advantageously used as a liquid crystal display device or the like requiring driving in a wide temperature range such as a panel for a car navigation system or a panel for a smart phone because the voltage storage ratio is excellent and the thermal stability of the voltage storage ratio is small. do.

The liquid crystal aligning agent and the liquid crystal alignment film of the present invention exhibit a high voltage retention rate even at the time of using at a high temperature and can give a liquid crystal display element having a small voltage retaining ratio and thermal deterioration. Accordingly, the liquid crystal display element of the present invention is suitably used as a liquid crystal display element or the like which is required to be driven in a wide temperature range such as a panel for car navigation, a panel for a smart phone, and the like.

(Mode for carrying out the invention)

<Liquid Crystal Aligner>

The liquid crystal aligning agent of the present invention is a liquid crystal aligning agent containing at least one compound selected from the group consisting of a polyamic acid obtained by reacting a tetracarboxylic acid dianhydride with a diamine and an imidated polymer thereof and the tetracarboxylic acid 2 Wherein the anhydride comprises a tetracarboxylic acid dianhydride having an aliphatic hydrocarbon group or an alicyclic hydrocarbon group, and the diamine includes a compound represented by the formula (1). The liquid crystal aligning agent may contain other arbitrary components as long as the effect of the present invention is not impaired. Hereinafter, the polyamic acid, its imide polymer, and other optional components will be described in detail.

<Polyamic acid>

The polyamic acid contained in the liquid crystal aligning agent of the present invention can be obtained by reacting a tetracarboxylic acid dianhydride with a diamine represented by the formula (1). The tetracarboxylic acid dianhydride includes an aliphatic or alicyclic tetracarboxylic acid dianhydride. As long as the effect of the present invention is not impaired, other optional components such as a molecular weight modifier may be used in addition to the tetracarboxylic acid dianhydride and diamine for the synthesis of the polyamic acid.

[Tetracarboxylic acid dianhydride]

The tetracarboxylic acid dianhydride for synthesizing the polyamic acid in the present invention is preferably a tetracarboxylic acid dianhydride having an aliphatic hydrocarbon group (hereinafter also referred to as &quot; aliphatic tetracarboxylic acid dianhydride &quot;) or an alicyclic dianhydride having an alicyclic hydrocarbon group Tetracarboxylic acid dianhydride (hereinafter, also referred to as "alicyclic tetracarboxylic acid dianhydride").

The aliphatic tetracarboxylic acid dianhydride refers to an aliphatic tetracarboxylic acid dianhydride having a structure in which at least one hydrogen atom is removed from an aliphatic chain hydrocarbon in a main chain or a side chain and four carboxyl groups bonded to the chain structure moiety are dehydrated in a molecule, . However, it is not necessarily composed of only a chain structure, and a part thereof may have a cyclic hydrocarbon structure or an aromatic ring structure.

The alicyclic tetracarboxylic acid dianhydride refers to an alicyclic tetracarboxylic acid dianhydride having a structure in which at least one hydrogen atom is removed from an alicyclic hydrocarbon in a main chain or a side chain and four carboxyl groups bonded to the alicyclic hydrocarbon are removed Anhydride and two carboxyl groups bonded to the alicyclic hydrocarbon moiety and two carboxyl groups bonded to the alicyclic hydrocarbon moiety and the chain hydrocarbon moiety having the structure of the alicyclic hydrocarbon and the structure of the chain hydrocarbon in the main chain or side chain, &Lt; / RTI &gt; However, it is not necessarily composed of only alicyclic hydrocarbon groups or chain hydrocarbon groups, and some of them may have an aromatic ring structure.

Examples of the aliphatic tetracarboxylic acid dianhydride include 1,2,3,4-butanetetracarboxylic dianhydride and the like. Examples of the alicyclic tetracarboxylic acid dianhydride include 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentyl acetic acid dianhydride, 1,3,3a , 4,5,9b-hexahydro-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [ 3a, 4,5,9b-hexahydro-8-methyl-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [ , 3-oxabicyclo [3.2.1] octane-2,4-dione-6-spiro-3 '- (tetrahydrofuran-2', 5'- 3-cyclohexene-1,2-dicarboxylic anhydride, 3,5,6-tricarboxy-2-carboxymethylnorbornane-2: 3,5: 6- Dianhydride, bicyclo [3.3.0] octane-2,4,6,8-tetracarboxylic dianhydride, 4,9-dioxatricyclo [5.3.1.0 ^2,6 ] undecane-3,5,8 , 10-tetraone, cyclohexanetetracarboxylic acid dianhydride, and the like. Other aliphatic tetravalent dianhydrides and alicyclic tetracarboxylic dianhydrides described in JP-A-2010-97188 can be used.

Examples of the aliphatic or alicyclic tetracarboxylic acid dianhydride include 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentyl acetic acid dianhydride, 1,3,3a, (Tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] furan-1,3-dione, 1,3,3a , 4,5,9b-hexahydro-8-methyl-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [ Bicyclo [3,3,0] octane-2,4,6,8-tetracarboxylic acid dianhydride, cyclohexanetetracarboxylic dianhydride and 1,2,3,4-butanetetracarboxylic dianhydride are preferable (1S, 2S, 4R, 5R) -cyclohexanetetracarboxylic dianhydride, (1R, 2S, 4S, 5R) -cyclohexanetetracarboxylic acid dianhydride, Acid anhydride and 2,3,5-tricarboxycyclopentyl acetic acid dianhydride are more preferable, and 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride is more preferable. The aliphatic or alicyclic tetracarboxylic acid dianhydrides may be used singly or in combination of two or more.

As the tetracarboxylic acid dianhydride, only aliphatic or alicyclic tetracarboxylic acid dianhydrides may be used. In addition to aliphatic or alicyclic tetracarboxylic acid dianhydrides, tetracarboxylic dianhydrides having aromatic rings (aromatic tetracarboxylic acids 2 anhydride) may be used in combination. Here, the "aromatic tetracarboxylic acid dianhydride" is an acid anhydride obtained by intramolecular dehydration of four carboxyl groups having at least one aromatic ring in the main chain or side chain and bonding to the same or different aromatic rings.

Examples of the aromatic tetracarboxylic acid dianhydride include pyromellitic dianhydride (PMDA), biphenyltetracarboxylic acid dianhydride, benzophenonetetracarboxylic dianhydride, naphthalenetetracarboxylic dianhydride, 4,4'-oxene And an aromatic tetracarboxylic acid dianhydride described in JP-A-2010-97188. Of these, PMDA, biphenyltetracarboxylic acid dianhydride, naphthalenetetracarboxylic acid dianhydride and 4,4'-oxydiphthalic anhydride are preferable, and PMDA is more preferable. Since PMDA is excellent in liquid crystal alignability, it is preferable that PMDA is combined with an aliphatic or alicyclic tetracarboxylic acid dianhydride so that the alignment property in the liquid crystal alignment film can be improved. On the other hand, when aliphatic or alicyclic tetracarboxylic acid dianhydrides are used alone, they are preferable because they can increase the voltage holding ratio as compared with a mixed system of aromatic tetracarboxylic dianhydrides.

The total amount of the aliphatic or alicyclic tetracarboxylic acid dianhydride is preferably 10 to 100 mol%, more preferably 30 to 100 mol%, and still more preferably 50 to 100 mol%, based on the total amount of the tetracarboxylic acid dianhydride. Mol, more preferably from 60 to 100 mol%. By setting the ratio of the aliphatic or alicyclic tetracarboxylic acid dianhydride to the above-mentioned specific range, a high voltage holding ratio can be exhibited when the liquid crystal alignment film is used, and the rubbing resistance can be improved.

When the aliphatic or alicyclic tetracarboxylic acid dianhydride and the aromatic tetracarboxylic acid dianhydride are used in combination as the tetracarboxylic acid dianhydride, the ratio of the aromatic tetracarboxylic dianhydride to the aromatic tetracarboxylic dianhydride is preferably such that the total amount of the tetracarboxylic acid dianhydride , Preferably from 10 to 45 mol%, and more preferably from 20 to 40 mol%. By setting the ratio of the aromatic tetracarboxylic dianhydride to the above-mentioned specific range, it is possible to improve the liquid crystal alignment property while improving the voltage holding ratio when the liquid crystal alignment film is formed.

[Diamine]

In the present invention, at least a part of the diamine used for synthesizing polyamic acid is a compound represented by the above formula (1).

In the above formula (1), X ¹ and X ³ are each independently a single bond, an oxygen atom or a sulfur atom. X ² and X ⁴ are, independently of each other, an alkyl group having 1 to 6 carbon atoms. m and n are each independently 0 or 1; However, both m and n do not become zero.

Examples of the alkyl group having 1 to 6 carbon atoms represented by X ² and X ⁴ include a methyl group, an ethyl group, a propyl group, and a butyl group. Of these, a methyl group and an ethyl group are preferable, and a methyl group is more preferable.

X ¹ and X ³ are preferably a single bond or -O-, more preferably a single bond.

As m and n, it is preferable that the benzene ring of the diamine represented by the formula (1) has a substituent only on one side of the ortho position of the amide. By such a structure, the solubility of the resulting polyamic acid in a solvent can be improved.

Examples of the compound represented by the formula (1) include compounds represented by the following formulas.

Among the compounds represented by the above formula (1), those represented by the above formulas (1-1) to (1-5) are preferable, and the compound represented by the above formula (1-1) (4-amino-2-methoxyphenyl) benzamide) and the compound represented by the above formula (1-2) (4-amino-N- (4-amino-2-methylphenyl) benzamide) represented by the above formula (1-1) is more preferable.

As the diamine for synthesizing the polyamic acid in the present invention, only the compound represented by the formula (1) may be used, or the diamine other than the compound represented by the formula (1) may be used in combination.

Examples of other diamines usable herein include aliphatic diamines, alicyclic diamines, diaminoorganosiloxanes, aromatic diamines, and the like.

Examples of the aliphatic diamines include 1,1-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'-diaminodiphenylsulfide, 1 , 5-diaminonaphthalene, 2,2'-dimethyl-4,4'-diaminobiphenyl, 4,4'-diamino-2,2'-bis (trifluoromethyl) biphenyl, 2,7 Diaminodiphenyl ether, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 9,9-bis (4-aminophenyl) fluorene, (4-aminophenoxy) phenyl] hexafluoropropane, 2,2-bis (4-aminophenyl) hexafluoropropane, 4,4 '- Bis (4-aminophenoxy) benzene, 4,4'-bis (4-aminophenoxy) benzene, Phenyl, 2,6-diaminopyridine, 3,4-diaminopyridine, 2,4-diaminopyrimidine, 3,6-diamino acridine, 3,6-diaminocarbazole, , 6-diaminocarboxylic acid N, N'-bis (4-aminophenyl) -benzidine, N, N'-bis 4-aminophenyl) -piperazine, 3,5-diaminobenzoic acid, dodecaneoxy-2,4-diaminobenzene, Tetradecanoxy-2,4-diaminobenzene, pentadecanoxy-2,4-diaminobenzene, hexadecanoxy-2,4-diaminobenzene, octadecanoxy-2,4-diaminobenzene, dodecane Oxy-2,5-diaminobenzene, tetradecanoxy-2,5-diaminobenzene, pentadecanoxy-2,5-diaminobenzene, hexadecaneoxy- 2,5-diaminobenzene, octadecanoxy- 2,5-diaminobenzene, cholestanyloxy-3,5-diaminobenzene, cholestenyloxy-3,5-diaminobenzene, cholestanyloxy-2,4-diaminobenzene, cholestenyl Oxy-2,4-diaminobenzene, 3,5-diaminobenzoic acid cholestanyl, 3,5-diaminobenzoic acid cholestenyl, 3,5-diaminobenzoic acid ranostanyl, Bis (4-aminophenoxy) cholestane, 4- (4'-trifluoromethoxybenzoyloxy) cyclohexyl-3,5-diamino Benzoate, 4- (4'-trifluoromethylbenzoyloxy) cyclohexyl-3,5-diaminobenzoate, 1,1-bis (4- (aminophenyl) methyl) Heptylcyclohexane, 1,1-bis (4 - ((aminophenoxy) methyl) phenyl) -4-heptylcyclohexane , 1,1-bis (4 - ((aminophenyl) methyl) phenyl) -4- (4-heptylcyclohexyl) cyclohexane, 2,4- diamino- Amine, 3-aminobenzylamine, 1- (2,4-diaminophenyl) piperazine-4-carboxylic acid, 4- (morpholin- (N- (4-aminophenyl) piperidinyl) propane,? -Amino-? - aminophenyl alkylene and compounds represented by the following formula (A-1).

In the above formula (A-1), R ¹ and R ³ are each a single bond, -O-, -COO- or -OCO-. R ² is a single bond, a methylene group or an alkylene group having 2 or 3 carbon atoms. p is 0 or 1; q is an integer of 0 to 2. r is an integer of 1 to 20; However, both of p and q do not become zero. In addition, all of R ¹ to R ³ are not single bonds.

Examples of the divalent group represented by -R ¹ -R ² -R ³ - in the above formula (A-1) include a methylene group, an alkylene group having 2 or 3 carbon atoms, ^* -O-, ^* -COO- or ^* O-CH ₂ CH ₂ -O- (where "*" represents a site bonding with a diaminophenyl group). Examples of the group C _r H _{2r + 1} - include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group, a n-hexyl group, , n-decyl, n-dodecyl, n-tridecyl, n-tetradecyl, n-pentadecyl, n-hexadecyl, n-heptadecyl, Decyl group, n-eicosyl group, and the like. 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 compounds represented by the following formulas (A-1-1) to (A-1-3).

As other diamines, other than the above-mentioned compounds, the diamines described in JP-A-2010-97188 include compounds other than the above-mentioned diamines.

The proportion of the compound represented by the formula (1) is preferably 10 to 100 mol% based on the total amount of the diamine. By setting the ratio of the compound represented by the formula (1) to the above specific range, the liquid crystal alignment film formed from the liquid crystal aligning agent can exert excellent liquid crystal alignability. In addition, the liquid crystal display element having the liquid crystal alignment film can also increase the voltage holding ratio of the liquid crystal when used at a high temperature.

[Molecular Weight Regulator]

In the synthesis of the polyamic acid, the endmodified polymer may be synthesized by using an appropriate molecular weight regulator together with the tetracarboxylic acid dianhydride and the diamine. When the polyamic acid is a polymer having such 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 modifier include acid anhydrides, monoamine compounds, and monoisocyanate compounds.

Examples of the acid anhydrides 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, n-octylamine and the like;

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

The use ratio of the molecular weight modifier 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.

&Lt; Synthesis method of polyamic acid &gt;

The polyamic acid in the present invention can be synthesized by reacting a tetracarboxylic acid dianhydride with a diamine in a solvent. The ratio of the tetracarboxylic acid dianhydride to the diamine used in the synthesis reaction of the polyamic acid is preferably 0.2 to 2 equivalents of the tetracarboxylic acid dianhydride to the equivalent of 1 equivalent of the amino group of the diamine, To 1.2 equivalents is more preferable.

As a solvent used for synthesis of polyamic acid, an organic solvent is preferable. The reaction temperature at this time is preferably -20 ° C to 150 ° C, more preferably 0 ° C to 100 ° C. The reaction time is preferably 0.1 hour to 24 hours, more preferably 0.5 hours to 12 hours.

Examples of the organic solvent include aprotic polar solvents, phenols and derivatives thereof, alcohols, ketones, esters, ethers, halogenated hydrocarbons and hydrocarbons.

Examples of the aprotic polar solvent include N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, dimethylsulfoxide, , Hexamethylphosphoric triamide, and the like.

Examples of the phenol and derivatives thereof include m-cresol, xylenol, halogenated phenol, and the like.

Examples of the alcohols include methyl alcohol, ethyl alcohol, isopropyl alcohol, cyclohexanol, ethylene glycol, propylene glycol, 1,4-butanediol, triethylene glycol, and ethylene glycol monomethyl ether.

Examples of the ketone include acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone.

Examples of the esters include ethyl lactate, butyl lactate, methyl acetate, ethyl acetate, butyl acetate, methyl methoxypropionate, ethyl ethoxypropionate, diethyl oxalate and diethyl malonate.

Examples of the ether include diethyl ether, ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol-n-propyl ether, ethylene glycol-i-propyl ether, ethylene glycol- Ethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, tetraethylene glycol monomethyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monomethyl ether acetate, And hydrofuran.

Examples of the halogenated hydrocarbons include dichloromethane, 1,2-dichloroethane, 1,4-dichlorobutane, trichloroethane, chlorobenzene, o-dichlorobenzene and the like.

Examples of the hydrocarbons include 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 an aprotic polar solvent and a group consisting of a phenol and a derivative thereof (first group of organic solvents), or at least one selected from organic solvents of the first group and an alcohol , A ketone, an ester, an ether, a halogenated hydrocarbon and a hydrocarbon (an organic solvent of the second group), more preferably an organic solvent of the first group , Aprotic polar solvent is more preferable, and N-methyl-2-pyrrolidone is particularly preferable. Further, it is preferable that one or more members selected from the first group of organic solvents and one or more members selected from the group consisting of alcohols, ketones, esters, ethers, halogenated hydrocarbons and hydrocarbons (second group of organic solvents) When the mixture is used, the use ratio of the organic solvent of the second group is preferably 50% by mass or less, more preferably 40% by mass or less based on the total amount of the organic solvent of the first group and the organic solvent of the second group , And more preferably 30 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 0.1 to 50 mass% with respect to the total amount of the reaction solution.

As described above, a reaction solution obtained by dissolving polyamic acid is obtained. This reaction solution may be used as it is for preparing a liquid crystal aligning agent as it is, or may be used for preparing a liquid crystal aligning agent after isolating the polyamic acid contained in the reaction solution. Alternatively, after the isolated polyamic acid is purified, it may be used for preparing a liquid crystal aligning agent. Further, the polyamic acid can be isolated and purified by a known method.

<Imidized Polymer>

The imidized polymer (polyimide) in the present invention can be obtained by imidizing the synthesized polyamic acid by dehydration ring closure. In this case, the reaction solution obtained by dissolving polyamic acid 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 dehydration ring-closing reaction. Alternatively, the polyamic acid isolated may be purified and then subjected to a dehydration ring-closing reaction.

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 of the polyimide. Dehydration ring closure of only a part of the acid structure may be carried out, 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%, 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.

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 heating the polyamic acid as necessary, 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 ° C to 180 ° C, more preferably 10 ° C to 150 ° C. The reaction time is preferably 1.0 hour to 120 hours, more preferably 2.0 hours to 30 hours.

In this way, a reaction solution containing polyimide is obtained. This reaction solution may be provided as it is in the preparation of a liquid crystal aligning agent or may be provided in the preparation of a liquid crystal aligning agent after removing the dehydrating agent and the dehydration ring-closing catalyst from the reaction solution. Alternatively, after the polyimide is isolated, Or may be provided to the preparation of a liquid crystal aligning agent after purification of the isolated polyimide. These purification operations can be carried out according to a known method.

&Lt; Solution viscosity of polymer &gt;

The polyamic acid or imidized polymer (hereinafter also referred to as a specific polymer) in the present invention obtained as described above has a solution viscosity of 20 mPa · s to 800 mPa · s And more preferably a solution viscosity of 30 mPa · s to 500 mPa · s. Here, the solution viscosity (mPa 占 퐏) of the specific polymer was determined by using an E-type rotational viscometer with respect to a polymer solution having a concentration of 10 mass% of the specific polymer prepared using N-methyl-2-pyrrolidone ℃.

&Lt; Other optional components &gt;

The liquid crystal aligning agent of the present invention contains a specific polymer, but may contain other optional components as required. Other optional components include, for example, an organic solvent, other polymers other than the above specific polymer, a compound having at least one epoxy group in the molecule (hereinafter referred to as an &quot; epoxy compound &quot;), a functional silane compound, .

[Organic solvents]

The liquid crystal aligning agent of the present invention is usually constituted by dissolving and containing a specific polymer and optionally other arbitrary components optionally mixed 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. Of these, aprotic polar solvents are preferable, N-methyl-2-pyrrolidone and? -Butyrolactone are more preferable, and N-methyl-2-pyrrolidone is more preferable. These may be used alone or in combination of two or more.

[Other Polymers]

These other polymers can be used for improvement of solution characteristics and electrical properties. The other polymer is a polymer other than the specific polymer. For example, a reaction between a diamine and a polyamic acid and an aromatic tetracarboxylic acid dianhydride obtained by reacting a diamine containing no compound represented by the formula (1) with a tetracarboxylic dianhydride (Hereinafter also referred to as &quot; other polyimide &quot;), polyamic acid ester, polyester, polyamide, polysiloxane, and polyimide obtained by dehydration ring closure of other polyamic acids Cellulose derivatives, polyacetals, 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. Examples of tetracarboxylic dianhydrides and diamines used for synthesizing other polyamic acids or other polyimides include the compounds used for synthesizing the above specific polymers.

When the other polymer is added to the liquid crystal aligning agent, the blending ratio thereof is preferably 50 mass% or less, more preferably 0.1 to 40 mass%, and further preferably 0.1 to 30 mass%, based on the total polymer amount in the liquid crystal aligning agent More preferable.

[Epoxy Compound]

The epoxy compound can be used for improving the mechanical strength in the liquid crystal alignment film. As a result, film peeling and the like can be suppressed (rubbing resistance can be improved) at the time of rubbing treatment, and further, defective display in the liquid crystal display element can be suppressed. The epoxy compound may also be used for the purpose of improving adhesion between the liquid crystal alignment film and the substrate.

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 ether, N , N, N ', N'-tetraglycidyl-m-xylenediamine, 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, Tetraglycidyl-4,4'-diaminodiphenylmethane, N, N-diglycidyl-benzylamine, N, N-diglycidylaminomethylcyclohexane and N, Dicyclohexylamine is preferred.

When these epoxy compounds are added to the liquid crystal aligning agent, the mixing ratio thereof is preferably 40 parts by mass or less, more preferably 0.1 parts by mass to 30 parts by mass, relative to 100 parts by mass of the total amount of the polymers contained in the liquid crystal aligning agent.

[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-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, N-phenyl- N-phenyl-3-aminopropyltriethoxysilane, glycidoxymethyltrimethoxysilane, glycidoxymethyltriethoxysilane, 2-glycidoxyethyltrimethoxysilane, 2-glycidoxyethyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, and the like.

When these functional silane compounds are added to the liquid crystal aligning agent, the blending ratio thereof is preferably 2 parts by mass or less, more preferably 0.02 to 0.2 parts by mass per 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 prepared by dissolving and containing a specific polymer and optionally other components optionally blended in the organic solvent.

The solid concentration in the liquid crystal aligning agent (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., % 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 is preferably 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% The film thickness of the coating film becomes too small to obtain a good liquid crystal alignment film. On the other hand, when the solid concentration exceeds 10% by mass, the film thickness of the coating film becomes excessively large, which makes it difficult to obtain a good liquid crystal alignment film, and the viscosity of the liquid crystal aligning agent is increased and the coating property may be deteriorated.

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 a range of 1.5% by mass to 4.5% by mass. In the case of the printing method, it is preferable that the solid concentration is set in the range of 3% by mass to 9% by mass, and the solution viscosity is set in the range of 12 (mPa · s) to 50 (mPa · s). In the case of the ink jet method, it is preferable that the solid concentration is in the range of 1% by mass to 5% by mass, and accordingly, the solution viscosity is in the range of 3 (mPa 占 퐏) to 15 (mPa 占 퐏). The temperature for preparing the liquid crystal aligning agent of the present invention is preferably 10 to 50 캜, more preferably 20 to 30 캜.

<Liquid Crystal Alignment Film and Liquid Crystal Display Device>

The liquid crystal alignment film of the present invention is formed by the above liquid crystal aligning agent. Further, the liquid crystal display element of the present invention comprises the liquid crystal alignment film. The liquid crystal alignment film may be applied to a horizontal alignment type liquid crystal display device such as an IPS type, a TN type or an STN type and may be applied to a vertical alignment type liquid crystal display device such as a VA type. It is more preferable to apply to the IPS type.

Hereinafter, a method of manufacturing a liquid crystal display element of the present invention will be described, and a method of manufacturing a liquid crystal alignment film of the present invention will be described. The liquid crystal display element of the present invention can be produced, for example, by the following steps (1) to (3). In the step (1), the substrate to be used differs for each desired operation mode. Steps (2) and (3) are common to each operation mode.

[Process (1): Formation of coating film]

First, the liquid crystal aligning agent is applied on the substrate, and then the coated surface is heated to form a coating film on the substrate.

(1-1) In the case of producing a TN type, STN type or VA type liquid crystal display device;

The liquid crystal aligning agent of the present invention is preferably applied by offset printing, spin coating, roll coater method, or inkjet printing method on each of the transparent conductive film forming surfaces of the two substrates on which the patterned transparent conductive film is formed, (Preferably two-step heating comprising preheating (pre-baking) and baking (post baking)) to form a coating film. Examples of the substrate include glass such as float glass and soda glass; A transparent substrate made of plastic such as polyethylene terephthalate, polybutylene terephthalate, polyether sulfone, polycarbonate, and poly (alicyclic olefin) can be used. As the transparent conductive film to be formed on one surface of the substrate, an ITO film made of NESA film (a registered trademark of PPG Corporation of the US) or indium oxide-tin oxide (In ₂ O ₃ -SnO ₂ ) made of tin oxide (SnO ₂ ) In order to obtain a patterned transparent conductive film, for example, a method of forming a pattern by photoetching after forming a transparent conductive film without a pattern, a method of using a mask having a desired pattern in forming a transparent conductive film, etc. Can be done. In the application of the liquid crystal aligning agent, a functional silane compound, a functional titanium compound, or the like is added to the surface of the substrate on which the coating film should be formed, in order to further improve the adhesion between the substrate surface and the transparent conductive film and the coating film May be carried out in advance.

The coated surface after the application of the liquid crystal aligning agent is then preheated (prebaked) and further baked (post baked) to form a coated 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 formed coating film is preferably 0.001 to 1 mu m, more preferably 0.005 to 0.5 mu m.

(1-2) In case of manufacturing an IPS type liquid crystal display element;

The liquid crystal aligning agent of the present invention is respectively applied to the conductive film formation surface of the substrate on which the transparent conductive film patterned in the comb shape is formed and the opposing substrate on which the conductive film is not formed, . The material, the coating method, the heating conditions after application, the patterning method of the transparent conductive film, the pretreatment of the substrate, and the preferable film thickness of the coating film to be formed are the same as those in the above (1-1).

In both cases (1-1) and (1-2), the liquid crystal aligning agent is coated on the substrate, and then the organic solvent is removed to form a coating film to be an alignment film. At this time, when the polymer contained in the liquid crystal aligning agent of the present invention is a polyamic acid or an imidized polymer having an imidazole ring structure and an arboric acid structure, the dehydration ring-closure reaction is further advanced by further heating after forming the coating film, Or may be a coated film.

[Process (2): rubbing treatment]

In the case of producing a TN type, STN type or IPS type liquid crystal display device, a rubbing process is performed in which a coating film formed as described above is rubbed in a predetermined direction with a roll formed of a fiber made of nylon, rayon or cotton, for example . Accordingly, the alignment ability of the liquid crystal molecules is imparted to the coating film to form a liquid crystal alignment film.

The liquid crystal alignment film may be subjected to a treatment for changing a pretilt angle of a part of the liquid crystal alignment film by irradiating a part of the liquid crystal alignment film with ultraviolet rays or a process for forming a resist film on a part of the surface of the liquid crystal alignment film, It is possible to improve the clock characteristic of the liquid crystal display element obtained by performing a process of removing the resist film after performing the rubbing treatment in different directions and making the liquid crystal alignment film have different liquid crystal aligning ability for each region.

In the case of manufacturing a VA type liquid crystal display device, the coating film formed as described above can be directly used as a liquid crystal alignment film, but the rubbing treatment may be performed.

[Process (3): Construction of liquid crystal cell]

With respect to a pair of substrates having the liquid crystal alignment film formed as described above, the liquid crystal alignment films of the two substrates are opposed to each other with a gap (cell gap) interposed therebetween such that the rubbing directions are orthogonal or anti- Are bonded by using a sealant, liquid crystal is injected and filled in the cell gap defined by the surface of the substrate and the sealant, and the injection port is sealed to construct the liquid crystal cell. The liquid crystal display element can be obtained by bonding a polarizing plate on the outer surface of the liquid crystal cell so that the polarizing direction thereof coincides with or orthogonal to the rubbing direction of the liquid crystal alignment film formed on each substrate.

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

Examples of the liquid crystal include nematic liquid crystal and smectic liquid crystal. Among them, a nematic liquid crystal is preferable. Examples thereof include a cypher base liquid crystal, an agglutinative liquid crystal, a biphenyl liquid crystal, a phenyl cyclohexane liquid crystal, , Terphenyl-based liquid crystals, biphenylcyclohexane-based liquid crystals, pyrimidine-based liquid crystals, dioxane-based liquid crystals, bicyclooctane-based liquid crystals, quaternary type liquid crystals and the like. Further, to these liquid crystals, for example, cholesteric liquid crystals such as cholesteryl chloride, cholesteryl nonanoate and cholesteryl carbonate; Chiral agents such as those sold under the trade names "C-15" and "CB-15" (Merck); p-decyloxybenzylidene-p-amino-2-methylbutyl cinnamate and the like may be added and used.

As the polarizing plate to be bonded to the outer surface of the liquid crystal cell, for example, a polarizing plate in which a polarizing film called "H film" in which iodine is absorbed while polyvinyl alcohol is oriented in a stretched state is sandwiched by a cellulose acetate protective film or a polarizing plate .

The liquid crystal display element of the present invention can be effectively applied to various apparatuses and can be applied to various devices such as a clock, a portable game, a word processor, a notebook type personal computer, a car navigation system, a camcorder, a PDA, , Various monitors, liquid crystal TVs, and the like. Particularly, the liquid crystal display element exhibits a high voltage holding ratio even at a high temperature, and since the voltage holding ratio thereof is small, the liquid crystal display element is required to be driven in a wide temperature range such as a car navigation panel, Device and the like.

[Example]

Hereinafter, the present invention will be described more specifically by way of examples, but the present invention is not limited to these examples. In the following Synthesis Examples, 4-amino-N- (4-amino-2-methylphenyl) benzamide and 4-amino- Commercial products "MDABAN" and "MODABAN" of Sunyang Pharmaceutical were used as they were. The solution viscosities of the polymers in the respective Synthesis Examples were values measured at 25 占 폚 using an E-type rotational viscometer.

<Synthesis of polyamic acid>

[Synthesis Examples 1 to 6]

Diamine and tetracarboxylic acid dianhydride in the amounts shown in Table 1 were added in this order to N-methyl-2-pyrrolidone to prepare a solution having a monomer concentration of 15 mass%. Thereafter, a reaction was performed at room temperature for 6 hours to obtain solutions each containing polyamic acid ((PA-1), (PA-2), (PAR-1) to (PAR-4)). A small amount of each solution was collected and N-methyl-2-pyrrolidone (NMP) was added to obtain a solution having a polymonic acid concentration of 10 mass%. The solution viscosity was measured and the results are shown in Table 1 below.

In Table 1, the abbreviations of the diamine and the tetracarboxylic acid anhydride have the following meanings respectively.

<Diamine>

d-1: 4-Amino-N- (4-amino-2-methylphenyl)

d-2: 4-Amino-N- (4-amino-2-methoxyphenyl)

d-3: 4,4-diaminodiphenylamine

d-4: Diaminodiphenyl ether

d-5: Diaminodiphenylmethylene

d-6: 4-Aminophenyl-4'-aminobenzoate

&Lt; Tetracarboxylic acid dianhydride &gt;

t-1: 1,2,3,4-Cyclobutane tetracarboxylic acid dianhydride (CB)

&Lt; Preparation of liquid crystal aligning agent &

[Examples 1 to 2 and Comparative Examples 1 to 4]

Butyrolactone (BL), N (N-methylpyrrolidone), and N-butyrolactone were added to a solution containing each of the polyamic acids (PA-1), N-methyl-2-pyrrolidone (NMP) and butyl cellosolve (BC) were further added to the mixture, and furthermore, N, N, N ', N'-tetraglycidyl- 2 parts by mass of diphenylmethane was added to 100 parts by mass of the total of 100 parts by mass of the polymer to obtain a solution having a solvent composition of BL: NMP: BC = 30: 50: 20 (mass ratio) and a solid content concentration of 6% by mass. This solution was filtered using a filter having a pore diameter of 1 탆 to prepare each liquid crystal aligning agent.

&Lt; Production of liquid crystal cell (liquid crystal display element) &gt;

Each liquid crystal aligning agent was applied to a glass substrate having a thickness of 1 mm having a chromium electrode formed in a comb shape on one side by a spinner and prebaked on a hot plate at 80 DEG C for 1 minute, For 10 minutes to form a coating film having a thickness of about 800 ANGSTROM. The rubbing treatment was carried out using a rubbing machine having a roll having a roll of nylon cloth formed thereon at a revolution speed of 1,000 rpm, a moving speed of the stage of 25 mm / sec, and a piercing length of 0.4 mm, . The substrate was ultrasonically cleaned in ultrapure water for 1 minute and dried in a 100 ° C clean oven for 10 minutes to produce a substrate having a liquid crystal alignment film on the surface having a comb-like chromium electrode. The substrate having this liquid crystal alignment film is referred to as &quot; substrate A &quot;.

Separately, a coating film of each liquid crystal aligning agent was formed on one surface of a 1 mm-thick glass substrate having no electrode, rubbed, cleaned, and dried to obtain a substrate having a liquid crystal alignment film on one surface, . The substrate having this liquid crystal alignment film is referred to as &quot; substrate B &quot;.

Subsequently, an epoxy resin adhesive containing aluminum oxide spheres having a diameter of 5.5 mu m was applied to the outer edge of the surface having the rubbed liquid crystal alignment film of the substrate, and then the two substrates A and B were coated so that the rubbing direction in each liquid crystal alignment film was antiparallel, B were arranged opposite to each other with a gap therebetween, and the outer edges were pressed against each other to cure the adhesive. Subsequently, a nematic liquid crystal (MLC-2042 manufactured by Merck Co., Ltd.) was filled from a liquid crystal injection hole between the pair of substrates, and then a liquid crystal injection hole was sealed with an acrylic photo-curable adhesive to produce an IPS liquid crystal cell.

<Evaluation>

Each liquid crystal cell prepared as described above was subjected to the following evaluations.

[Voltage Conservation Rate (%)]

The liquid crystal cell prepared above was subjected to a voltage of 1 V for 30 seconds at 100 占 폚 and a voltage maintenance ratio (%) after application was canceled at a frame cycle of 167 msec at 100 占 폚. (A) &quot;, the case where the voltage holding ratio exceeds 90% is defined as &quot; good (A) &quot;, the case where it exceeds 80% I appreciated. The evaluation results are shown in Table 2.

[Thermal reliability (%)]

For the liquid crystal cell prepared above, the voltage holding ratio at 100 캜 was measured at a frame period of 167 msec, and then the thermal stress was applied at 100 캜 for 30 hours. Then, the voltage holding ratio at 100 캜 was measured again at a frame period of 167 msec. The value obtained by subtracting the voltage holding ratio (%) after stress application from the voltage holding ratio (%) before the stress application is equivalent to the thermal deterioration equivalent to the voltage holding ratio. When the value is less than 3%, the thermal reliability is &quot; (B) "in the case of 3% or more and less than 8%, and" Defective (C) "in the case of 8% or more. The evaluation results are shown in Table 2.

It was found that the liquid crystal cell having the liquid crystal alignment film produced using the liquid crystal aligning agents of Examples 1 and 2 had a higher voltage holding ratio as compared with Comparative Examples 1 to 4. Further, the liquid crystal cells of Examples 1 and 2 were small in thermal deterioration of the voltage holding ratio and excellent in thermal reliability.

The liquid crystal aligning agent and the liquid crystal alignment film of the present invention exhibit a high voltage retention rate even at the time of using at a high temperature and can give a liquid crystal display element having a small voltage retaining ratio and thermal deterioration. Accordingly, the liquid crystal display element of the present invention is suitably used as a liquid crystal display element or the like which is required to be driven in a wide temperature range such as a panel for car navigation, a panel for a smart phone, and the like.

Claims (8)

1. A liquid crystal aligning agent containing at least one compound selected from the group consisting of a polyamic acid obtained by reacting a tetracarboxylic dianhydride with a diamine and an imidized polymer thereof,
Wherein the tetracarboxylic acid dianhydride comprises a tetracarboxylic dianhydride having an aliphatic hydrocarbon group or an alicyclic hydrocarbon group,
The liquid crystal aligning agent is characterized in that the diamine includes a compound represented by the following formula (1)

(Wherein X ¹ and X ³ are each independently a single bond, an oxygen atom or a sulfur atom, X ² and X ⁴ are each independently an alkyl group having 1 to 6 carbon atoms, m and n Are independently 0 or 1, provided that both of m and n are not 0). The method according to claim 1,
Wherein m is 1 and n is 0 or m is 0 and n is 1 in the formula (1). The method according to claim 1,
Wherein the aliphatic hydrocarbon group or alicyclic hydrocarbon group-containing tetracarboxylic acid dianhydride is selected from 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride, 2,3,5-tricarboxycyclopentyl acetic acid dianhydride, 1 , 3,3a, 4,5,9b-hexahydro-8-methyl-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [ 3-dione, 1,3,3a, 4,5,9b-hexahydro-5- (tetrahydro-2,5-dioxo-3-furanyl) 3-dione, bicyclo [3,3,0] octane-2,4,6,8-tetracarboxylic acid dianhydride, cyclohexanetetracarboxylic dianhydride, and 1,2,3,4-butanetetracarboxylic acid 2 &lt; / RTI &gt; anhydride. The method of claim 3,
Wherein the aliphatic hydrocarbon group or alicyclic hydrocarbon group-containing tetracarboxylic acid dianhydride is selected from the group consisting of 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride, (1S, 2S, 4R, 5R) -cyclohexanetetracarboxylic acid A liquid crystal aligning agent which is at least one compound selected from the group consisting of dianhydrides, (2R, 2S, 4S, 5R) -cyclohexanetetracarboxylic dianhydride and 2,3,5-tricarboxycyclopentyl acetic acid dianhydride, . 5. The method according to any one of claims 1 to 4,
Wherein the tetracarboxylic acid dianhydride is at least one aromatic compound selected from the group consisting of pyromellitic anhydride, biphenyltetracarboxylic acid dianhydride, naphthalenetetracarboxylic acid dianhydride, and 4,4'-oxydiphthalic anhydride, Further comprising a liquid crystal aligning agent. 6. The method of claim 5,
Wherein the tetracarboxylic acid dianhydride further comprises pyromellitic acid anhydride. A liquid crystal alignment film formed by the liquid crystal aligning agent according to any one of claims 1 to 4. A liquid crystal display element comprising the liquid crystal alignment film according to claim 7.