KR20170098787A - Liquid crystal aligning agent, liquid crystal alignment film, and liquid crystal display device - Google Patents

Abstract

Provided is a liquid crystal alignment agent which gives a liquid crystal alignment film that not only is capable of obtaining good pre-tilt characteristics by a light aligning method, but also does not cause display performance to be degraded even in a case of long-term continuous driving. The liquid crystal alignment agent contains (A) a polyamic acid A obtained by making tetracarbon acid dianhydride react with diamine including diamine having a photoreactive structure, and (B) a polyamic acid B obtained by making at least one tetracarbon acid dianhydride selected from the group consisting of 1,2,3,4-cyclobutanetetracarbon acid dianhydride and pyromellitic acid dianhydride react with at least one diamine selected from the group consisting of 2,2-dimethyl-4,4-diaminobiphenyl, p-phenylenediamine, 4,4-diaminodiphenylmethane, and 4,4-diaminodiphenylether, wherein the polyamic acid A is excluded from the polyamic acid B.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention 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. More specifically, the present invention relates to a liquid crystal aligning agent which gives a liquid crystal alignment film which is excellent in printability and does not cause deterioration of display performance even when continuously driven for a long time.

Conventionally, as an operation mode of a liquid crystal display device, TN (Twisted Nematic) type, STN (Super Twisted Nematic) type, etc. using liquid crystal molecules having positive dielectric anisotropy and liquid crystal molecules having negative dielectric anisotropy A VA (Vertical Alignment) type using molecules, and the like. In order to control the orientation of liquid crystal molecules, a liquid crystal alignment film mainly composed of an organic film is used (Patent Documents 1 to 4).

The liquid crystal alignment layer in the TN type, the STN type, and the like needs to have a pretilt angle characteristic in order to make the slope direction at the time of liquid crystal driving constant for the liquid crystal alignment film in the VA type or the like, have. As a method for imparting the pretilt angular characteristic, a rubbing method for the former, a rubbing method for the former, a method for forming protrusions on the surface of the substrate, and the like have been common. Among them, the rubbing method may cause a problem of display failure or circuit breakage due to dust or static electricity generated in the process. On the other hand, a method of forming protrusions on the surface of the substrate is problematic in that when the luminance of the obtained liquid crystal display element is damaged There were all problems, such as.

As a pretilt angle applying method instead of these methods, a so-called photo alignment method has been proposed in which ultraviolet rays are irradiated to the photosensitive thin film from an oblique direction with respect to a film normal line (Patent Document 5 and Non-Patent Document 1).

2. Description of the Related Art In recent years, a liquid crystal display device has been developed particularly for television applications, and has been realized for a very long time compared with a conventional liquid crystal display device. However, it is known that when the conventionally known liquid crystal display element is continuously driven for a long time, display quality is deteriorated. One of the reasons is thought to be that the liquid crystal alignment film is deteriorated by exposure to light for a long time by driving for a long time. Therefore, in the field of liquid crystal alignment films, materials that do not cause deterioration of display performance even when continuous driving is performed for a long time have been studied.

For example, in Patent Document 6, use of an alignment film material having a crosslinking (crosslinking) structure has been proposed. However, the degree of suppression of display quality deterioration in the case of continuous driving for a long time is not sufficient by the technique of the same document.

Further, it has been pointed out that if a liquid crystal aligning agent known in the production of a liquid crystal alignment film is used, printing defects such as printing unevenness and pinholes occur with a certain probability in the formed film, resulting in insufficient product yield in the production of the liquid crystal alignment film have.

Japanese Laid-Open Patent Publication No. 56-91277 Japanese Unexamined Patent Application Publication No. 1-120528 Japanese Patent Application Laid-Open No. 11-258605 Japanese Patent Application Laid-Open No. 2002-250924 Japanese Patent Application Laid-Open No. 2004-83810 Japanese Patent Application Laid-Open No. 2008-216985

 J. of the SID 11/3, 2003, p579  T. J. Scheffer et al., J. Appl. Phys. vo. 19, p2013 (1980)

An object of the present invention is to provide a liquid crystal aligning agent which can obtain good pre-tilt characteristics by the photo alignment method and which does not cause deterioration of display performance even when continuously driven for a long time.

Another object of the present invention is to provide a liquid crystal aligning agent excellent in printability.

According to the present invention,

(A) a polyamic acid A obtained by reacting a tetracarboxylic acid dianhydride with a diamine containing a diamine having a photoreactive structure, and

(B) at least one tetracarboxylic acid dianhydride selected from the group consisting of 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride and pyromellitic acid dianhydride, and 2,2'-dimethyl- At least one diamine selected from the group consisting of 4'-diaminobiphenyl, p-phenylenediamine, 4,4'-diaminodiphenylmethane and 4,4'-diaminodiphenyl ether. Polyamic acid B (except for the above polyamic acid A)

And a liquid crystal aligning agent.

The liquid crystal aligning agent of the present invention is superior in printing property as compared with a liquid crystal aligning agent conventionally known as a liquid crystal aligning agent to which a photo alignment method can be applied and causes deterioration of display performance even when the liquid crystal aligning agent is continuously driven for a long time It is possible to form a liquid crystal alignment film.

Therefore, when the liquid crystal alignment film of the present invention is applied to a liquid crystal display element, the obtained liquid crystal display element is excellent in performance such as its display characteristics and reliability. Therefore, the liquid crystal display device can be effectively applied to various apparatuses, and is thus well suited for devices such as a tabletop calculator, a wristwatch, a desk clock, a counting display board, a word processor, a personal computer, and a liquid crystal television Can be used to make.

(Mode for carrying out the invention)

The liquid crystal aligning agent of the present invention, as described above,

(A) a polyamic acid A obtained by reacting a tetracarboxylic acid dianhydride with a diamine containing a diamine having a photoreactive structure, and

(B) at least one tetracarboxylic acid dianhydride selected from the group consisting of 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride and pyromellitic acid dianhydride, and 2,2'-dimethyl- At least one diamine selected from the group consisting of 4'-diaminobiphenyl, p-phenylenediamine, 4,4'-diaminodiphenylmethane and 4,4'-diaminodiphenyl ether. Polyamic acid B (except for the above-mentioned polyamic acid A).

[Polyamic acid A]

≪ Tetracarboxylic acid dianhydride >

Examples of the tetracarboxylic acid dianhydride used for synthesizing the polyamic acid A in the present invention include aliphatic tetracarboxylic acid dianhydride, alicyclic tetracarboxylic acid dianhydride, and aromatic tetracarboxylic dianhydride . Specific examples thereof include aliphatic tetracarboxylic acid dianhydrides such as butanetetracarboxylic dianhydride;

As the alicyclic tetracarboxylic acid dianhydride, for example, 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride, 2,3,5-tricarboxycyclopentyl acetic acid dianhydride, 1,3,3a, 4, 5,9b-hexahydro-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2- c] furan-1,3-dione, , 5,9b-hexahydro-8-methyl-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [ (Tetrahydrofuran-2 ', 5'-dione), 5- (2,5-dioxotetrahydro-3 ' 3-cyclohexene-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: 3,5: 6-2 anhydride, 4,9-dioxatricyclo [5.3.1.0 ^2,6 ] undecane- , 5,8,10-tetralone, and the like;

As the aromatic tetracarboxylic acid dianhydride, for example, pyromellitic dianhydride can be used, and tetracarboxylic acid dianhydride described in Japanese Patent Application No. 2009-157556 can be used.

Among the tetracarboxylic acid dianhydrides used for synthesizing the polyamic acid, those containing an alicyclic tetracarboxylic acid dianhydride are preferable, and those containing 2,3,5-tricarboxycyclopentyl acetic acid dianhydride .

As the tetracarboxylic acid dianhydride used for synthesizing the polyamic acid, it is preferable that 2,3,5-tricarboxycyclopentylacetic acid dianhydride is contained in an amount of 10 mol% or more based on the total tetracarboxylic acid dianhydride, More preferably 20 mol% or more.

Examples of the tetracarboxylic acid dianhydride used for synthesizing the polyamic acid include 2,3,5-tricarboxycyclopentyl acetic acid dianhydride or 2,3,5-tricarboxycyclopentyl acetic acid dianhydride and 1, , And 2,3,4-cyclobutanetetracarboxylic acid dianhydride.

<Diamine>

The diamine used for synthesizing polyamic acid A in the present invention includes a diamine having a photoreactive structure.

The photoreactive structure is preferably a structure having a function capable of at least one reaction selected from isomerization and dimerization by irradiation with light, and examples thereof include a structure represented by the following formula (A-2):

(In the formula (A-2), d is 0 or 1, and A ¹ and A ² are each an alkyl group having 1 to 6 carbon atoms, an alkoxyl group having 1 to 6 carbon atoms, a halogen atom or a cyano group, 0 &quot; to &quot; 4 &quot; and &quot; + &quot;

As shown in Fig.

As A ¹ and A ^{2 in the} above formula (A-2), each is preferably an alkoxyl group having 1 to 6 carbon atoms or a halogen atom. e and f are each preferably 0 or 1, and more preferably 0.

The diamine having a photoreactive structure preferably has a moiety having a function of orienting liquid crystal molecules. Examples of the photoreactive structure having such a moiety include the following formulas (A-2-1) and A-2-2):

(In the formulas (A-2-1) and (A-2-2), A ¹ , A ² , d, e and f have the same meanings as those in formula (A-

R ^I and R ^II are each an alkyl group having 1 to 40 carbon atoms in which a part or all of the hydrogen atoms may be substituted with a fluorine atom,

X ^II and X ^III are each -O-, -CO-, -CO-O-, -O-CO-, -NR-, -NR-CO-, -CO-NR-, -NR-CO-O- -O-CO-NR-, -NR-CO-NR- or -O-CO-O- wherein R is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms,

R ^III are each a methylene group, an arylene group, a divalent alicyclic _{group, -Si (CH 3) 2 -} , and -CH = CH- or -C≡C-, R stage ^III having one or two of the hydrogen atoms A halogen atom or an alkyl group having 1 to 4 carbon atoms, h is an integer of 1 to 6, i is an integer of 0 to 2, and when a plurality of X ^II and R ^III exist , They may be the same or different, j is 0 or 1, and &quot; + &quot;

And at least one structure selected from the structure represented by each of the above-mentioned structures.

In the formula (A-2-1) and (A-2-2), an alkyl group having 1 to 40 carbon atoms in which some or all of the hydrogen atoms of R ^I and R ^II may be substituted with a fluorine atom, As the alkyl group of 40, for example, an alkyl group having 1 to 20 carbon atoms (provided that a part or all of the hydrogen atoms of the alkyl group may be substituted by a fluorine atom) is preferable. Examples of such alkyl groups include n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, N-hexadecyl group, n-heptadecyl group, n-octadecyl group, n-nonadecyl group, n-eicosyl group, A 4,4,5,5,5-pentafluoropentyl group, a 4,4,5,5,6,6,6-heptafluorohexyl group, a 3,3,4,4-tetrafluorobutyl group, Heptafluoropentyl group, 2,2,2-trifluoroethyl group, 2,2,3,3,3-pentafluoropropyl group, 2- (perfluorobutyl) ethyl group , A 2- (perfluorooctyl) ethyl group, a 2- (perfluorodecyl) ethyl group, and the like.

As the alkyl group having 1 to 40 carbon atoms in which a part or all of the hydrogen atoms may be substituted with a fluorine atom, a linear or branched fluoroalkyl group having 1 to 16 carbon atoms is preferable, and from the viewpoint of exhibiting good liquid crystal alignability, More preferably a straight chain fluoroalkyl group having 3 to 6 carbon atoms, and still more preferably a straight chain fluoroalkyl group having 3 to 6 carbon atoms. For example, 2,2,2-trifluoroethyl group, 3,3,3-trifluoro-n-propyl group, 4,4,4-trifluoro-n-butyl group, 5,5-pentafluoro-n-pentyl group, 4,4,5,5,6,6,6-heptafluorohexyl group and the like, and 2,2,2-trifluoroethyl group, 3 , 3,3-trifluoro-n-propyl group, 4,4,4-trifluoro-n-butyl group and 4,4,5,5,5-pentafluoro-n-pentyl group are preferable.

X ^II and X ^III are each preferably -O-.

The diamine having a photoreactive structure may have one or two or more such photo-orientable structures in one molecule, and it is preferable that the diamine has one or two such structures.

Specific examples of the diamine having such a photoreactive structure include those having a structure represented by the above formula (A-2-1), for example, the following formulas (A-2-1-1) to (A- ) And (A-2-1-16) to (A-2-1-27):

(A-2-2-1) to (A-2-2-2): those having the structure represented by the formula (A-2-2)

, And the like.

As the diamine used for synthesizing the polyamic acid A, a diamine other than the diamine having the above photoreactive structure may be used in combination. Examples of other diamines usable herein include aliphatic diamines, alicyclic diamines, aromatic diamines, diaminoorganosiloxanes, and the like. Specific examples thereof include aliphatic diamines such as 1,1-meta-xylylenediamine, 1,3-propanediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine and the like;

As the alicyclic diamine, for example, 1,4-diaminocyclohexane, 4,4'-methylenebis (cyclohexylamine), 1,3-bis (aminomethyl) cyclohexane and the like;

As aromatic diamines, for example, p-phenylenediamine, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfide, 1,5-diaminonaphthalene, 2,2'-dimethyl Diaminobiphenyl, 4,4'-diamino-2,2'-bis (trifluoromethyl) biphenyl, 2,7-diaminofluorene, 4,4'-diamino Diphenyl ether, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 9,9- Bis (4-aminophenyl) hexafluoropropane, 4,4 '- (p-phenylenediisopropylidene) bisaniline,

Bis (4-aminophenoxy) benzene, 4,4'-bis (4-aminophenoxy) biphenyl, 2,6 Diaminopyridine, 3, 6-diaminocarbazole, 3,6-diaminocarbazole, N-methyl-3,6-diamino N, N'-bis (4-aminophenyl) -benzidine, N, N'-bis (4-aminophenyl) -N, N'-dimethylbenzidine, 1,4-bis- (4-aminophenyl) -piperazine, 3,5-diaminobenzoic acid, dodecaneoxy- , Tetradecanoxy-2,4-diaminobenzene, pentadecanoxy-2,4-diaminobenzene, hexadecanoxy-2,4-diaminobenzene,

Octadecanoxy-2,4-diaminobenzene, dodecaneoxy-2,5-diaminobenzene, tetradecanoxy-2,5-diaminobenzene, pentadecanoxy-2,5-diaminobenzene, hexadecane Oxy-2,5-diaminobenzene, octadecanoxy-2,5-diaminobenzene, cholestanyloxy-3,5-diaminobenzene, cholestenyloxy-3,5-diaminobenzene, Diaminobenzene, 3,5-diaminobenzoic acid cholestanyl, 3,5-diaminobenzoic acid cholestenyl, 3,5-diaminobenzoic acid cholestanyl, 3,5- (4-aminobenzoyloxy) cholestane, 3,6-bis (4-aminophenoxy) cholestane, 4- (4'-trifluoromethoxybenzoyloxy) Bis (4 - ((aminophenyl) -1,3,5-diaminobenzoyl) cyclohexyl-3, 5-diaminobenzoate, 4- (4'-trifluoromethylbenzoyloxy) Methyl) phenyl) -4-butylcyclohexane,

(4 - ((aminophenoxy) methyl) phenyl) -4-heptylcyclohexane, 1, 1-bis Cyclohexane and the following formula (A-1): 1-bis (4 - ((aminophenyl) methyl) phenyl) -4-

(Wherein (A-1) of, X ^I are also combined with an alkyl group, ^* -O-, ^* -COO- or ^* -OCO- (However, the combined hand-diamino phenyl group attached the '*' of a carbon number of 1 to 3 A is 0 or 1, b is an integer of 0 to 2, and c is an integer of 1 to 20)

And the like;

As the diaminoorganosiloxane, for example, 1,3-bis (3-aminopropyl) -tetramethyldisiloxane and the like can be used, and diamines described in Japanese Patent Application No. 2009-157556 can be used .

X ^I in the above formula (A-1) is preferably an alkyl group having 1 to 3 carbon atoms, ^* -O- or ^* -COO- (provided that the bond with "*" is bonded to a diaminophenyl group) Do. Specific examples of the group C _c H _{2c +1} - include a methyl group, an ethyl group, a n-propyl group, an n-butyl group, an n-pentyl group, N-hexadecyl group, n-heptadecyl group, n-octadecyl group, n-octadecyl group, n-hexadecyl group, - nonadecyl group, and n-eicosyl group. The two amino groups in the diaminophenyl group are preferably in the 2,4-position or the 3,5-position with respect to the other groups.

Specific examples of the compound represented by the above formula (A-1) include compounds represented by the following formulas (A-1-1) to (A-1-4)

And the like.

In the above formula (A-1), it is preferable that a and b are not 0 at the same time.

[Composition of diamine]

The diamine used for synthesizing the polyamic acid A in the present invention contains a diamine having the above photoreactive structure and may optionally further contain at least one other diamine.

The diamine having a photoreactive structure used for synthesizing polyamic acid A in the present invention is preferably contained in an amount of from 50 to 99 mol%, more preferably from 80 to 95 mol%, based on the total diamine.

[Molecular Weight Regulator]

In synthesizing the polyamic acid A, a terminal modifier type polymer may be synthesized using a suitable molecular weight modifier together with the tetracarboxylic dianhydride and the diamine as described above. By making such a polymer of the terminal modification type, the coating property (printing property) of the liquid crystal aligning agent can be improved without impairing the effect of the present invention.

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

Specific examples thereof include acid anhydrides such as maleic anhydride, phthalic anhydride, itaconic anhydride, n-decylsuccinic anhydride, n-dodecylsuccinic anhydride, n-tetradecylsuccinic anhydride, n-hexadecylsuccinic anhydride My back;

As the monoamine compound, for example, 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 regulator is preferably 20 parts by weight or less, more preferably 10 parts by weight or less, based on 100 parts by weight of the total amount of tetracarboxylic acid dianhydride and diamine to be used.

<Synthesis of polyamic acid A>

The ratio of the tetracarboxylic dianhydride and the diamine to be used in the synthesis reaction of the polyamic acid A 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, More preferably 0.3 to 1.2 equivalents.

The synthesis reaction of the polyamic acid is preferably carried out in an organic solvent at a temperature of preferably -20 ° C to 150 ° C, more preferably 0 to 100 ° C, preferably 0.1 to 120 hours, more preferably 0.5 to 48 hours Time is done.

Examples of the organic solvent include N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, dimethylsulfoxide, Non-protonic polar solvents such as hexamethylphosphoric triamide and hexamethylphosphoric triamide; phenol solvents such as m-cresol, xylenol, phenol, and halogenated phenol. The amount (a) of the organic solvent used is preferably such that the total amount (b) of the tetracarboxylic acid dianhydride and the diamine is 0.1 to 50 wt% with respect to the total amount (a + b) of the reaction solution.

In this way, a reaction solution obtained by dissolving polyamic acid can be obtained.

The reaction solution may be directly supplied to the preparation of the liquid crystal aligning agent. Alternatively, the polyamic acid contained in the reaction solution may be isolated and then supplied to the preparation of the liquid crystal aligning agent, or after the isolated polyamic acid is purified, .

[Polyamic acid B]

The polyamic acid B is at least one tetracarboxylic acid dianhydride selected from the group consisting of 1,2,3,4-cyclobutane tetracarboxylic acid dianhydride and pyromellitic acid dianhydride, and 2,2'-dimethyl-4 , At least one diamine selected from the group consisting of 4'-diaminobiphenyl, p-phenylenediamine, 4,4'-diaminodiphenylmethane, and 4,4'-diaminodiphenyl ether is reacted Lt; / RTI &gt;

In order to synthesize the polyamic acid B, the specific tetracarboxylic acid dianhydride, the tetracarboxylic acid dianhydride other than the diamine, and the diamine may be used in combination. Other diamines that can be used herein include, for example, tetracarboxylic acid dianhydrides used for synthesizing polyamic acid A and the same diamines as those described above (however, diamines having no photoreactive structure are not included) .

The tetracarboxylic acid dianhydride used for synthesizing the polyamic acid B can be obtained by reacting 1,2,3,4-cyclobutanetetracarboxylic dianhydride and pyromellitic dianhydride in an amount of 50 Mol% or more, and more preferably 80 mol% or more.

The diamines used for synthesizing the polyamic acid B include 2,2'-dimethyl-4,4'-diaminobiphenyl, p-phenylenediamine, 4,4'-diaminodiphenylmethane, 4,4 ' -Aminodiphenyl ether is preferably contained in an amount of 50 mol% or more, more preferably 80 mol% or more, based on the total diamine used.

The polyamic acid B can be synthesized in the same manner as the polyamic acid A described above.

The polyamic acid A is preferably contained in an amount of 10 to 70% by weight, more preferably 20 to 50% by weight, based on the sum of the polyamic acid A and the polyamic acid B. If the proportion of the polyamic acid A is less than 10% by weight based on the total of the polyamic acid A and the polyamic acid B, the pretilt angle light resistance may be lowered. If the proportion is more than 70% by weight, .

<Other components>

The liquid crystal alignment film of the present invention contains the above specific polymer as an essential component, but may contain other components as required. Examples of such other components include a polymer other than the specific polymer (hereinafter referred to as "another polymer"), a compound having at least one epoxy group in the molecule (hereinafter referred to as "epoxy compound"), a functional silane compound And the like.

[Other Polymers]

These other polymers can be used for improving solution properties and electrical properties. Such other polymer is a polymer other than the specific polymer as described above, and may be a polyamic acid other than polyamic acid A and polyamic acid B (hereinafter referred to as &quot; other polyamic acid &quot;), polyimide obtained by dehydrocondensing polyamic acid, Poly (styrene-phenylmaleimide) derivatives, poly (meth) acrylates, and the like can be given. Of these, other polyamic acids are preferable.

[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, 2,2-dibromoneopentyl glycol diglycidyl ether, 1,3,5, Tetraglycidyl-2,4-hexanediol, N, N, N ', N'-tetraglycidyl-m-xylylenediamine, 1,3-bis (N, N-diglycidylamino Methyl) cyclohexane, N, N, N ', N'-tetraglycidyl-4,4'-diaminodiphenylmethane, N, N-diglycidyl- Di-aminomethylcyclohexane, and the like. The compounding ratio of these epoxy group-containing compounds is preferably 40 parts by weight or less, more preferably 0.1 to 30 parts by weight, based on 100 parts by weight 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- Ethoxy silyl propyl triethylenetriamine,

Trimethoxysilyl-1,4,7-triazadecane, 10-triethoxysilyl-1,4,7-triazadecane, 9-trimethoxysilyl-3,6-diazanonyl acetate, Benzyl-3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltriethoxysilane, N-benzyl- Aminopropyltriethoxysilane, N-bis (oxyethylene) -3-aminopropyltrimethoxysilane, N-bis (oxyethylene) -3-aminopropyltriethoxy Silane, and the like.

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

<Liquid Crystal Aligner>

The liquid crystal aligning agent of the present invention is constituted by dissolving and incorporating the above-mentioned specific polymer and optionally other additives optionally mixed in an organic solvent.

Examples of the organic solvent that can be used as the liquid crystal aligning agent of the present invention include the solvents exemplified for use in the synthesis reaction of polyamic acid. In addition, an organic solvent believed to be a poor solvent for conventional polyamic acid and polyimide can be suitably selected and used in combination. Preferable examples of such an organic solvent include N-methyl-2-pyrrolidone,? -Butyrolactone,? -Butyrolactam, N, N-dimethylformamide, N, N- Methylene-2-pentanone, ethylene glycol monomethyl ether, butyl lactate, butyl acetate, methyl methoxypropionate, ethyl ethoxypropionate, ethylene glycol methyl ether, ethylene glycol ethyl ether,

Ethylene glycol-propyl ether, ethylene glycol-n-butyl ether (butyl cellosolve), ethylene glycol dimethyl ether, ethylene glycol ethyl ether acetate, diethylene glycol dimethyl ether, diethylene glycol Diethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diisobutyl ketone, isoamyl propionate, isoamyl isobutyrate , Diisopentyl ether, cyclohexanone, diacetone alcohol, ethyl carbitol, ethoxyethyl propionate, butyl cellosolve acetate, carbitol acetate, propylene carbonate and the like. These may be used alone or in combination of two or more.

The solid concentration of the liquid crystal aligning agent of the present invention (the ratio of the total weight of the liquid crystal aligning agent excluding the organic solvent to the total weight of the liquid crystal aligning agent) is appropriately selected in consideration of viscosity, volatility, etc., 1 to 10% by weight. That is, the liquid crystal aligning agent of the present invention is applied to the substrate surface to remove the organic solvent to form a coating film to be a liquid crystal alignment film. When the solid concentration is less than 1 wt%, the film thickness of the coating film becomes too small, It is difficult to obtain a liquid crystal alignment film. On the other hand, when the solid concentration exceeds 10% by weight, the film thickness of the coating film becomes excessively large so that it is difficult to obtain a good liquid crystal alignment film in some cases. There is a case where the coating property is lowered.

Particularly preferable range of the solid concentration varies 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 range of 1.5 to 4.5 wt% is particularly preferable. In the case of the printing method, the solid concentration is preferably in the range of 3 to 9% by weight.

&Lt; Method of forming liquid crystal alignment film &

The liquid crystal aligning agent of the present invention can be suitably used for forming a liquid crystal alignment film by a photo alignment method.

As a method of forming the liquid crystal alignment film, for example, a liquid crystal aligning agent is coated on a substrate to form a coating film, and the coating film is irradiated with polarized or non-polarized ultraviolet rays obliquely on the coated film surface, And irradiating ultraviolet rays from a direction perpendicular to the coated film surface to give a liquid crystal aligning ability to the coated film.

First, the liquid crystal aligning agent of the present invention is applied to the transparent electroconductive film side of the substrate on which the patterned transparent electroconductive film is formed by a suitable application method such as a roll coater method, a spinner method, a printing method, or an ink jet method. After the application, the coated surface is preheated (prebaked) and then 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, More preferably 10 to 100 minutes. The film thickness of the coated film after post-baking is preferably 0.001 to 1 占 퐉, and more preferably 0.005 to 0.5 占 퐉.

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, or the like can be used.

As the transparent conductive film, a NESA film made of SnO ₂ , an ITO film made of In ₂ O ₃ -SnO ₂ , or the like can be used. For patterning these transparent conductive films, a photo etching method, a method using a mask when forming a transparent conductive film, and the like are used.

In the application of the liquid crystal aligning agent, a functional silane compound, a titanate compound, or the like may be previously coated on the substrate and the transparent conductive film in order to further improve adhesion between the substrate or the transparent conductive film and the coating film.

Subsequently, the coating film is irradiated with ultraviolet rays of polarized light or unpolarized light to give a liquid crystal aligning ability, and the coating film becomes a liquid crystal alignment film. 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 300 to 400 nm are preferable. When the radiation to be used is polarized (linearly polarized light or partially polarized light), it may be irradiated from an oblique direction for giving a pretilt angle even if it is irradiated from a perpendicular direction to the coated film surface. On the other hand, in the case of irradiating non-polarized radiation, it is necessary to conduct irradiation from an oblique direction with respect to the coated film surface.

As the light source of the irradiation radiation, 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 and an excimer laser 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.

The irradiation dose of the radiation is preferably 1 J / m 2 or more and less than 10,000 J / m 2, and more preferably 10 to 3,000 J / m 2. Further, in the case of imparting the liquid crystal aligning ability to the coating film formed by the conventionally known liquid crystal aligning agent by the photo alignment method, a radiation dose of 10,000 J / m 2 or more was required. However, when the liquid crystal aligning agent of the present invention is used, a good liquid crystal aligning ability can be imparted even when the dose of radiation in the photo alignment method is 3,000 J / m2 or less, further 1,000 J / m2 or less, further 300 J / m2 or less, Which contributes to a reduction in the manufacturing cost of the display element.

<Manufacturing Method of Liquid Crystal Display Element>

The liquid crystal display element of the present invention comprises a liquid crystal alignment layer formed of the liquid crystal aligning agent of the present invention. The liquid crystal display element of the present invention can be produced, for example, as follows.

Two substrates on which the liquid crystal alignment film is formed as described above are prepared, and a liquid crystal is arranged between the two substrates to manufacture a liquid crystal cell. For example, the following two methods can be used to manufacture the liquid crystal cell.

The first method is a conventionally known method. First, two substrates are opposed to each other with a gap (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 to each other using a sealant. The liquid crystal is injected and filled in the cell gap, and then the injection hole is sealed, whereby the liquid crystal cell can be manufactured.

The second method is a so-called ODF (One Drop Fill) method. For example, an ultraviolet curable sealant is applied to a predetermined position on one of the two substrates on which the liquid crystal alignment film is formed, and 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, when the liquid crystal alignment film is horizontally oriented, by adjusting the angle formed by the polarization direction of the irradiated linearly polarized radiation and the angle between each substrate and the polarizing plate on the two substrates on which the liquid crystal alignment film is formed, the TN type or STN Type liquid crystal cell can be obtained. On the other hand, in the case where the liquid crystal alignment film is vertically aligned, a cell is constituted so that the directions of the easy axis of alignment in the two substrates on which the liquid crystal alignment film is formed are parallel, and the polarizing plate is polarized by 45 , So that a liquid crystal display element having vertically aligned liquid crystal cells can be obtained.

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

As the liquid crystal, for example, a nematic liquid crystal, a smectic liquid crystal and the like can be preferably used.

In the case of a TN type liquid crystal cell or an STN type liquid crystal cell, a nematic liquid crystal having positive dielectric anisotropy is preferable, and examples thereof include biphenyl type liquid crystal, phenyl cyclohexane type liquid crystal, ester type liquid crystal, terphenyl type liquid crystal, 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 agent sold under the trade names "C-15" and "CB-15" (Merck); p-decyloxybenzylidene-p-amino-2-methylbutyl cinnamate, and other ferroelectric liquid crystals.

On the other hand, in the case of a vertically aligned liquid crystal cell, a nematic liquid crystal having a negative dielectric anisotropy is preferable. For example, a dicyanobenzene liquid crystal, a pyridazine liquid crystal, a heptbase liquid crystal, , Phenylcyclohexane-based liquid crystal, and the like.

Examples of the polarizer used for the outside of the liquid crystal cell include 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 between cellulose acetate protective films or a polarizing plate made of H film itself .

The liquid crystal display of the present invention manufactured in this way has excellent display performance and does not deteriorate display performance even when used for a long time.

(Example)

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

The solution viscosity of the polymer and the imidization rate of the polyimide in the following Synthesis Examples were respectively evaluated by the following methods.

[Solution viscosity of polymer]

The solution viscosity (mPa s) of the polymer was measured at 25 캜 using an E-type rotational viscometer for each polymer solution.

[Imidization Rate of Polyimide]

A small amount of the polyimide-containing solution obtained in each of the synthesis examples was fractionated and added to pure water, and the resulting precipitate was recovered by filtration to isolate the polyimide. The polyimide was sufficiently dried under reduced pressure at room temperature, dissolved in deuterated dimethyl sulfoxide, and was determined by the following formula (1) from ¹ H-NMR measured at room temperature using tetramethylsilane as a reference material.

Imidization ratio (%) = (1-A ¹ / A ² × α) × 100 (1)

(In the formula (1), A ¹ is the peak area derived from the proton of the NH group near 10 ppm, A ² is the peak area derived from the other proton, and α is the peak area of the NH 3 group in the polyimide precursor The ratio of the number of other protons to one proton of the group)

&Lt; Synthesis Example of Polymer and Comparative Synthesis Example &

[Synthesis of polyamic acid A]

Synthesis Examples 1 to 31

Diamine and tetracarboxylic acid dianhydride shown in Table 1 were added in this order to 135 g of N-methyl-2-pyrrolidone to dissolve the diamine and the tetracarboxylic acid dianhydride in the reaction solution (PA-1) to (PA-31) were respectively reacted at 60 DEG C for 6 hours to obtain 150 g of solutions each containing 10 wt% of polyamic acids (PA-1) to (PA-31). The viscosities of the respective solutions obtained here are shown together in Table 1. &lt; tb &gt; &lt; TABLE &gt;

[Synthesis of polyimide]

Comparative Synthesis Examples 1 to 15

Diamine and tetracarboxylic acid dianhydride shown in Table 2 were added in this order to 135 g of N-methyl-2-pyrrolidone to dissolve the diamine and the tetracarboxylic acid dianhydride in the reaction solution (RPA-1) to (RPA-15) was obtained by reacting the solution at 60 占 폚 for 6 hours to obtain 150 g of a solution containing 10 wt% of the polyamic acids (RPA-1) to (RPA-15). The viscosities of the respective solutions obtained here are shown together in Table 1. &lt; tb &gt; &lt; TABLE &gt;

Then, pyridine and acetic anhydride in the amounts shown in Table 2 were added to each of the solutions containing the respective polyamic acids, and dehydration ring-closure reaction was carried out at 110 DEG C for 4 hours. After the dehydration ring closure reaction, the solvent in the system was replaced with new N-methyl-2-pyrrolidone (the pyridine used in the dehydration ring closure reaction and the acetic anhydride used in this operation were removed from the system) -1) to (RPI-15), respectively. The solution viscosity and the imidization rate of each polyimide measured by diluting to 10 wt% with addition of N-methyl-2-pyrrolidone were shown in Table 2, respectively.

In Tables 1 and 2, the abbreviations of the diamine and the tetracarboxylic acid dianhydride are as follows.

[Diamine]

The first diamine

d-1: The compound represented by the above formula (A-2-1-1)

d-2: Compound represented by the above formula (A-2-1-2)

d-3: Compound represented by the above formula (A-2-1-3)

d-4: Compound represented by the above formula (A-2-1-4)

d-5: Compound represented by the above formula (A-2-2-1)

d-6: Compound represented by the above formula (A-2-1-5)

d-7: Compound represented by the above formula (A-2-1-6)

d-8: Compound represented by the above formula (A-2-1-7)

d-9: Compound represented by the above formula (A-2-1-8)

d-10: Compound represented by the above formula (A-2-1-9)

d-11: Compound represented by the above formula (A-2-1-10)

d-12: Compound represented by the above formula (A-2-1-11)

d-13: Compound represented by the above formula (A-2-1-12)

d-14: Compound represented by the above formula (A-2-1-13)

The second diamine

d-15: 3,5-diaminobenzoic acid cholestanyl

d-16: 1-cholestanyloxy-2,4-diaminobenzene

d-17: 3,5-diaminobenzoic acid cholesteryl

[Tetracarboxylic acid dianhydride]

t-1: 1,3,3a, 4,5,9b-hexahydro-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [ , 3-dione

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

t-3: 2,3,5-tricarboxycyclopentyl acetic acid dianhydride

[Synthesis of polyamic acid B]

Synthesis Example OPA-1

98 g (0.50 mol) of 1,2,3,4-cyclobutane tetracarboxylic acid dianhydride and 110 g (0.50 mol) of pyromellitic dianhydride as tetracarboxylic dianhydrides and 4,4'-diaminodiphenylmethane 200 g (1.0 mole) of the compound (A) was dissolved in 230 g of N-methyl-2-pyrrolidone and 2,100 g of a mixed solvent composed of? -Butyrolactone and reacted at 40 占 폚 for 3 hours. To obtain a solution containing 10 wt% of polyamic acid (OPA-1). The solution viscosity of this polyamic acid solution was 125 mPa · s.

Synthesis Example OPA-2

(1.0 mole) of 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride as tetracarboxylic dianhydride and 210 g (1.0 mole) of 2,2'-dimethyl-4,4'-diaminobiphenyl as a diamine, Was dissolved in a mixed solvent consisting of 370 g of N-methyl-2-pyrrolidone and 3,300 g of? -Butyrolactone, and the reaction was carried out at 40 占 폚 for 3 hours to obtain a solution containing 10% by weight of polyamic acid (OPA- Solution. The solution viscosity of this polyamic acid solution was 160 mPa · s.

[Synthesis of polyimide]

Synthesis example OPI-3

(0.50 mol) of 2,3,5-tricarboxycyclopentyl acetic acid dianhydride as tetracarboxylic acid dianhydride, 43 g (0.40 mol) of p-phenylenediamine as a diamine compound and 3- (3,5-diaminobenzoyloxy ) Cholestan (52 g, 0.10 mole) was dissolved in 830 g of N-methyl-2-pyrrolidone and reacted at 60 DEG C for 6 hours. A small amount of the obtained polyamic acid solution was fractionated and N-methyl-2-pyrrolidone was added to measure the viscosity of the solution with a solid concentration of 10%. The viscosity was 60 mPa · s. Then, 1900 g of NMP was added to the obtained polyamic acid solution, and 40 g of pyridine and 51 g of acetic anhydride were added, followed by dehydration cyclization at 110 DEG C for 4 hours. After the imidization reaction, the solvent in the system was replaced with fresh N-methyl-2-pyrrolidone (pyridine and acetic anhydride used in the imidization reaction were removed from the system in this operation) (OPI-3) in an amount of about 15% by weight. The solution viscosity of the obtained polyimide solution was measured as a solution having a polyimide concentration of 10 wt% by adding a small amount of N-methyl-2-pyrrolidone to obtain a solution viscosity of 47 mPa · s.

Example 1

I. Preparation of liquid crystal aligning agent

The solution containing the polyamic acid (PA-1) obtained in Synthesis Example 1 and the solution containing the polyamic acid (OPA-2) obtained in Synthesis Example OPA- (BLA), N-methyl-2-pyrrolidone (NMP) and diethylene glycol diethyl ether (OPA-2) DEDG) was added and sufficiently stirred to obtain a solution having a solvent composition of BL: NMP: DEDG = 30: 20: 50 (weight ratio) and a solid content concentration of 3% by weight. This solution was filtered using a filter having a pore diameter of 1 탆 to prepare a liquid crystal aligning agent.

Ⅱ. Production of liquid crystal cell

The liquid crystal aligning agent prepared above was applied to the transparent electrode surface of a glass substrate with a transparent electrode made of an ITO film by a spin coating method and heated on a hot plate at 80 ° C for 1 minute to remove the solvent, Was heated (post-baking) in an oven at 200 占 폚 with nitrogen substitution for 40 minutes to form a coating film having an average film thickness of 1,000 占. Subsequently, polarizing ultraviolet rays 200 J / m &lt; 2 &gt; containing a bright line having a wavelength of 313 nm were irradiated from the direction tilted 40 DEG from the normal to the surface of the coating film using an Hg-Xe lamp and a Glan Taille prism to give liquid crystal alignability, . The same operation was repeated to prepare a pair of substrates (two substrates) each having a liquid crystal alignment film.

An epoxy resin adhesive containing an aluminum oxide sphere having a diameter of 5.5 占 퐉 was applied to the periphery of the surface having one liquid crystal alignment film of the above substrate by screen printing and then the liquid crystal alignment film faces of the pair of substrates were opposed to each other, Pressed so that the projection direction of the optical axis of the ultraviolet ray to the substrate surface was anti-parallel, and the adhesive was thermally cured at 150 DEG C for 1 hour. Subsequently, a negative-type liquid crystal (MLC-6608, manufactured by Merck Ltd.) was filled in the gap between the 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 to 120 캜 and then gradually cooled to room temperature to produce a liquid crystal cell.

The liquid crystal alignability, the pretilt angle and the voltage holding ratio were evaluated for the liquid crystal cell by the following method. The evaluation results are shown in Table 3.

Ⅲ. Evaluation of Liquid Crystal Cell

(1) Liquid crystal orientation

The presence or absence of an abnormal domain when the voltage of 5 V was turned on / off (applied / released) at 25 캜 was observed by a polarizing microscope, and the case where there was no abnormal domain was referred to as liquid crystal alignment Quot; good &quot;.

(2) Voltage Conservation Rate

A voltage of 5 V was applied to the liquid crystal cell prepared above at 70 캜 for an application time of 60 microseconds and a span of 167 milliseconds, and then the voltage maintenance ratio after 167 ms after the application was released was measured by a &quot; VHR-1 &quot;.

(3) Evaluation of pretilt light resistance

According to the method described in Non-Patent Document 2 (TJ Scheffer et al., J. Appl. Phys. 19, p2013 (1980)), the liquid crystal cell prepared above was subjected to a crystal rotation method using He- (Initial pretilt angle [theta] _IN ). Next, the liquid crystal cell was subjected to a 5,000 hour irradiation experiment with a weather meter using a carbon arc as a light source, and the pretilt angle was again measured (pretilt angle (? _AF ) after irradiation) by the same method as described above.

(4) Residual DC voltage

A rectangular wave of 30 Hz, 3 V, in which DC 5 V was superimposed on the liquid crystal cell prepared above was applied for 2 hours at an environmental temperature of 60 캜, and the voltage (residual DC Voltage) was obtained by the flicker erase method. This value is an index of the afterimage characteristic. When the value is approximately 150 mV or less, the afterimage characteristic can be said to be good, and it can be said that it is particularly excellent when it is approximately 50 mV or less.

Examples 2 to 34 and Comparative Examples 1 to 17

A liquid crystal aligning agent was prepared in the same manner as in Example 1 except that the polymer of the kind and the amount shown in Table 3 and Table 4 was used as the polymer in Example 1, and a liquid crystal cell was produced and evaluated.

The evaluation results are shown in Tables 3 and 4.

Example 35

IV. Preparation of liquid crystal aligning agent

The solution containing the polyamic acid (PA-1) obtained in Synthesis Example 1 and the polyamic acid (OPA-2) obtained in Synthesis Example OPA- -Butyrolactone (BL), N-methyl-2-pyrrolidone (NMP) and butyl cellosolve (BC) were added thereto and sufficiently stirred to prepare a solvent A solution having a composition of BL: NMP: BC = 71: 17: 12 (weight ratio) and a solid concentration of 6.0 wt% was prepared. This solution was filtered using a filter having a pore size of 1 탆 to prepare a liquid crystal aligning agent.

Ⅴ. Evaluation of printability

The liquid crystal aligning agent prepared above was applied to the transparent electrode surface of a glass substrate with a transparent electrode made of an ITO film using a liquid crystal alignment film printing machine (manufactured by Nihon Shinsengattsu Co., Ltd.) After the solvent was removed by heating (prebaking), the film was heated on a hot plate at 200 ° C for 10 minutes (post baking) to form a coating film having an average film thickness of 600 Å. The coating film was observed with a microscope having a magnification of 20 times to examine the presence of printing unevenness and pinholes. As a result, neither printing unevenness nor pinholes were observed, and printing properties were good.

Examples 36 to 65

(PA-2) to (PA-31) obtained in Synthesis Examples 2 to 31 were used in place of the polyamic acid (PA-1) obtained in Synthesis Example 1, An aligning agent was prepared and evaluated for printability. As a result, neither printing unevenness nor pinholes were observed, and the printability was good.

Comparative Examples 18 to 32

Except that the polyimides (RPI-1) to (RPI-15) obtained in Comparative Synthesis Examples 1 to 15 were used in place of the polyamic acid (PA-1) obtained in Synthesis Example 1, A liquid crystal aligning agent was prepared, and the printability was evaluated. As a result, uneven printing and pinholes were observed, and the printability was poor.

Comparative Example 33

Except that the polyamic acid (PA-16) obtained in Synthesis Example 16 was used instead of the polyamic acid (OPA-2) obtained in Synthesis Example 1, , And polyimide (OPI-3) obtained in Synthesis Example OPI-3 were used in the same manner as in Example 35, printing properties were evaluated. As a result, printing unevenness and pinholes were observed, Printability was poor.

Claims (6)

(A) a polyamic acid A obtained by reacting a tetracarboxylic acid dianhydride with a diamine containing a diamine having a photoreactive structure, and
(B) at least one tetracarboxylic acid dianhydride selected from the group consisting of 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride and pyromellitic acid dianhydride, and 2,2'-dimethyl- At least one diamine selected from the group consisting of 4'-diaminobiphenyl, p-phenylenediamine, 4,4'-diaminodiphenylmethane and 4,4'-diaminodiphenyl ether. Polyamic acid B (except for the above polyamic acid A)
Wherein the liquid crystal aligning agent is a liquid crystal aligning agent. The method according to claim 1,
Wherein the polyamic acid A is contained in an amount of 10 to 70% by weight based on the sum of the polyamic acid A and the polyamic acid B. The method according to claim 1,
Wherein the photoreactive structure is represented by the following formula (A-2):

(In the formula (A-2), d is 0 or 1, and A ¹ and A ² are each an alkyl group having 1 to 6 carbon atoms, an alkoxyl group having 1 to 6 carbon atoms, a halogen atom or a cyano group, 0 &quot; to &quot; 4 &quot; and &quot; + &quot;
As a liquid crystal alignment agent. The method of claim 3,
(A-2-1) and (A-2-2): wherein the structure represented by the formula (A-

(In the formulas (A-2-1) and (A-2-2), A ¹ , A ² , d, e and f have the same meanings as those in formula (A-
R ^I and R ^II are each an alkyl group having 1 to 40 carbon atoms in which a part or all of the hydrogen atoms may be substituted with a fluorine atom,
X ^II and X ^III are each -O-, -CO-, -CO-O-, -O-CO-, -NR-, -NR-CO-, -CO-NR-, -NR-CO-O- -O-CO-NR-, -NR-CO-NR- or -O-CO-O- wherein R is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms,
R ^III are each a methylene group, an arylene group, a divalent alicyclic _{group, -Si (CH 3) 2 -} , and -CH = CH- or -C≡C-, R stage ^III having one or two of the hydrogen atoms The above-mentioned groups may be substituted with a cyano group, a halogen atom or an alkyl group having 1 to 4 carbon atoms,
h is an integer of 1 to 6,
i is an integer of 0 to 2,
When a plurality of X ^II and R ^III are present, they may be the same or different,
j is 0 or 1, and
&Quot; + &quot; represents a combined hand)
Wherein the liquid crystal aligning agent is at least one structure selected from the group consisting of a structure represented by each of the following formulas. 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 5.