JP2011158835A - Liquid crystal aligning agent - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal aligning agent giving a liquid crystal alignment layer with which favorable pretilt characteristics are obtained with a photo-aligning method and which brings about no degradation in display performance even in long-term continuous driving. <P>SOLUTION: The liquid crystal aligning agent contains: (A) a polyamic acid A obtained by making a tetracarboxylic acid dianhydride react with a diamine including a diamine having a photo-reactive structure; and (B) a polyamic acid B obtained by making at least one tetracarboxylic acid dianhydride selected from a group comprised of 1,2,3,4-cyclobutane tetracarboxylic acid dianhydride and pyromellitic acid dianhydride react with at least one diamine selected from a group comprised of 2,2'-dimethyl-4,4'-diamino biphenyl, p-phenylenediamine, 4,4'-diamino diphenylmethane, and 4,4'-diaminodiphenyl ether (wherein the polyamic acid A is excluded). <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a liquid crystal aligning agent. More specifically, the present invention relates to a liquid crystal aligning agent that provides a liquid crystal aligning film that is excellent in printability and does not deteriorate display performance even when continuously driven for a long time.

Conventionally, as an operation mode of a liquid crystal display element, a liquid crystal molecule having a negative dielectric anisotropy, such as a TN (twisted nematic) type using a liquid crystal molecule having a positive dielectric anisotropy, an STN (super twisted nematic) type, etc. A VA (Vertical Alignment) type using a liquid crystal is known, and a liquid crystal alignment film mainly composed of an organic film is used for controlling the alignment of liquid crystal molecules (Patent Documents 1 to 4).
The liquid crystal alignment film in the TN type, STN type, etc. has a pre-tilt angle characteristic because the liquid crystal alignment film in the VA type has a constant tilt direction when driving the liquid crystal because the liquid crystal molecules respond at high speed. . As a method for imparting this pretilt angle characteristic, the rubbing method is generally used in the former, the rubbing method is used in the latter, and a method of providing a protrusion on the substrate surface. Of these, the rubbing method may cause problems such as display defects and circuit destruction due to dust and static electricity generated in the process, while the method of providing protrusions on the substrate surface impairs the brightness of the liquid crystal display element obtained. All of them had problems.
Therefore, as an alternative pretilt angle providing method, a so-called photo-alignment method has been proposed by irradiating the photosensitive thin film with ultraviolet rays obliquely with respect to the film normal (Patent Document 5 and Non-Patent Document 1).

In recent years, liquid crystal display elements have been rapidly developed especially for television applications, and extraordinary long-time viewing has become a reality compared with conventional liquid crystal display elements. However, it is known that display quality deteriorates when a conventionally known liquid crystal display element is continuously driven for a long time. One of the reasons is considered to be that the liquid crystal alignment film is deteriorated by being exposed to light for a long time by being driven for a long time. For this reason, in the field of liquid crystal alignment films, materials that do not deteriorate display performance even when driven continuously for a long time have been studied.
For example, Patent Document 6 proposes the use of an alignment film material having a crosslinked structure. However, even with the technique of this document, the degree of suppression of display quality deterioration in the case of continuous driving for a long time is not sufficient.
In addition, when a liquid crystal aligning agent known in the past is used in the production of a liquid crystal alignment film, printing defects such as printing unevenness and pinholes occur with a certain probability in the formed coating film, and the product at the time of manufacturing the liquid crystal alignment film It is pointed out that the yield is insufficient.

JP 56-91277 A JP-A-1-120528 Japanese Patent Laid-Open No. 11-258605 JP 2002-250924 A JP 2004-83810 A JP 2008-216985 A

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

An object of the present invention is to provide a liquid crystal aligning agent that can provide a liquid crystal aligning film that can obtain good pretilt characteristics by a photo-alignment method and that does not deteriorate display performance even when continuously driven for a long time. There is to do.
Another object of the present invention is to provide a liquid crystal aligning agent excellent in printability.

According to the present invention, the above objects and advantages of the present invention are as follows.
(A) polyamic acid A obtained by reacting tetracarboxylic dianhydride with a diamine containing a diamine having a photoreactive structure, and (B) 1,2,3,4-cyclobutanetetracarboxylic dianhydride And at least one tetracarboxylic dianhydride selected from the group consisting of pyromellitic dianhydride, 2,2′-dimethyl-4,4′-diaminobiphenyl, p-phenylenediamine, 4,4 Polyamic acid B obtained by reacting at least one diamine selected from the group consisting of '-diaminodiphenylmethane and 4,4'-diaminodiphenyl ether (excluding the above polyamic acid A)
It is achieved by a liquid crystal aligning agent characterized by containing.

The liquid crystal aligning agent of the present invention is excellent in printability 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 when it is continuously driven for a long time. In addition, it is possible to form a liquid crystal alignment film that does not deteriorate the display performance.
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 various performances such as display characteristics and reliability. Therefore, the liquid crystal display element can be effectively applied to various devices, and can be suitably used for devices such as desk calculators, watches, table clocks, counting display boards, word processors, personal computers, and liquid crystal televisions.

The liquid crystal aligning agent of the present invention is as described above.
(A) polyamic acid A obtained by reacting tetracarboxylic dianhydride with a diamine containing a diamine having a photoreactive structure, and (B) 1,2,3,4-cyclobutanetetracarboxylic dianhydride And at least one tetracarboxylic dianhydride selected from the group consisting of pyromellitic dianhydride, 2,2′-dimethyl-4,4′-diaminobiphenyl, p-phenylenediamine, 4,4 It contains polyamic acid B obtained by reacting at least one diamine selected from the group consisting of '-diaminodiphenylmethane and 4,4'-diaminodiphenyl ether (excluding the above polyamic acid A).

[Polyamic acid A]
<Tetracarboxylic dianhydride>
Examples of tetracarboxylic dianhydrides used for synthesizing polyamic acid A in the present invention include aliphatic tetracarboxylic dianhydrides, alicyclic tetracarboxylic dianhydrides, and aromatic tetracarboxylic dianhydrides. And so on. Specific examples of these include aliphatic tetracarboxylic dianhydrides such as butane tetracarboxylic dianhydride;
Examples of the alicyclic tetracarboxylic dianhydride include 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentylacetic acid dianhydride, 1,3,3a, 4, 5,9b-Hexahydro-5- (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 [1,2-c] furan-1,3-dione, 3-oxabicyclo [3.2.1] octane -2,4-dione-6-spiro-3 '-(tetrahydrofuran-2', 5'-dione), 5- (2,5-dioxotetrahydro-3-furanyl) -3-methyl-3-cyclohexene- No 1,2-dicarboxylic acid 3,5,6-tricarboxy-2-carboxymethylnorbornane-2: 3,5: 6-dianhydride, 2,4,6,8-tetracarboxybicyclo [3.3.0] octane-2 : 3,5: 6-dianhydride, 4,9-dioxatricyclo [5.3.1.0 ^2,6 ] undecane-3,5,8,10-tetraone and the like;
Examples of the aromatic tetracarboxylic dianhydride include pyromellitic dianhydride and the like, and tetracarboxylic dianhydride described in Japanese Patent Application No. 2009-157556 can be used.

Among these, the tetracarboxylic dianhydride used for synthesizing the polyamic acid preferably includes an alicyclic tetracarboxylic dianhydride, and particularly 2,3,5-tricarboxycyclopentylacetic acid. It is preferable that it contains a dianhydride.
The tetracarboxylic dianhydride used for synthesizing the polyamic acid includes 2,3,5-tricarboxycyclopentylacetic acid dianhydride in an amount of 10 mol% or more based on the total tetracarboxylic dianhydride. It is preferable that it contains 20 mol% or more.
The tetracarboxylic dianhydride used for synthesizing the polyamic acid is composed only of 2,3,5-tricarboxycyclopentylacetic acid dianhydride or 2,3,5-tricarboxycyclopentyl. Most preferably, it consists only of acetic dianhydride and 1,2,3,4-cyclobutanetetracarboxylic dianhydride.

<Diamine>
The diamine used for synthesizing the 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 performing at least one reaction selected from isomerization and dimerization by light irradiation. For example, the photoreactive structure is represented by the following formula (A-2):

(In 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. Yes, e and f are each an integer of 0 to 4, and “+” indicates a bond.
The structure represented by can be mentioned.
A ¹ and A ² in the above formula (A-2) are each 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 further has a part having a function of aligning liquid crystal molecules. Examples of the photoreactive structure having such a part include the following formula (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 are respectively synonymous with those in the formula (A-2),
R ^I and R ^II are each an alkyl group having 1 to 40 carbon atoms in which some or all of the hydrogen atoms may be substituted with fluorine atoms,
X ^II and X ^III are respectively —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 is a methylene group, an arylene group, a divalent alicyclic group, —Si (CH ₃ ) ₂ —, —CH═CH— or —C≡C—, respectively, provided that R ^III has a hydrogen atom 1 or 2 or more 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, and i is an integer of 0 to 2. And when there are a plurality of X ^II and R ^III , they may be the same or different from each other, j is 0 or 1, and “+” is a bond, respectively. It shows that. )
And at least one structure selected from the structures represented by each of the above.

In the above formulas (A-2-1) and (A-2-2), part or all of the hydrogen atoms of R ^I and R ^II are alkyl groups having 1 to 40 carbon atoms which may be substituted with fluorine atoms. Yes,
The alkyl group having 1 to 40 carbon atoms is preferably, for example, an alkyl group having 1 to 20 carbon atoms, provided that part or all of the hydrogen atoms of the alkyl group may be substituted with fluorine atoms. Examples of such alkyl groups include, for example, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, n-nonyl group, n-decyl group, n-lauryl group, n-dodecyl group, n -Tridecyl group, n-tetradecyl group, n-pentadecyl group, n-hexadecyl group, n-heptadecyl group, n-octadecyl group, n-nonadecyl group, n-eicosyl group, 4,4,4-trifluorobutyl group, 4,4,5,5,5-pentafluoropentyl group, 4,4,5,5,6,6,6-heptafluorohexyl group, 3,3,4,4,5,5,5-heptafluoro group Pentyl group, 2,2,2-trifluoroethyl group, 2,2,3,3,3-pentafluoropropyl group, 2- (perfluorobutyl) ethyl group, 2- (perfluorooctyl) ethyl group, 2 -(Perf Orodeshiru) ethyl group and the like.
As the alkyl group having 1 to 40 carbon atoms in which some or all of the hydrogen atoms may be substituted with fluorine atoms, a linear or branched fluoroalkyl group having 1 to 16 carbon atoms is preferable, and a good liquid crystal From the viewpoint that the orientation can be expressed, a linear fluoroalkyl group having 1 to 8 carbon atoms is preferable, and a linear fluoroalkyl group having 3 to 6 carbon atoms is more preferable. For example, 2,2,2-trifluoroethyl group, 3,3,3-trifluoro-n-propyl group, 4,4,4-trifluoro-n-butyl group, 4,4,5,5,5- Examples include pentafluoro-n-pentyl group, 4,4,5,5,6,6,6-heptafluorohexyl group, 2,2,2-trifluoroethyl group, 3,3,3- A trifluoro-n-propyl group, a 4,4,4-trifluoro-n-butyl group, and a 4,4,5,5,5-pentafluoro-n-pentyl group are preferred.
X ^II and X ^III are each preferably —O—.
The diamine having a photoreactive structure may have one or two or more such photo-alignment structures in one molecule, and preferably has one or two such structures.

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

As compounds having the structure represented by the above formula (A-2-2), for example, the following formulas (A-2-2-1) to (A-2-2-2) )

And the like can be mentioned respectively.

As a diamine used for synthesizing the polyamic acid A, a diamine other than the diamine having the photoreactive structure can be used in combination. Examples of other diamines that can be used here include aliphatic diamines, alicyclic diamines, aromatic diamines, and diaminoorganosiloxanes. Specific examples thereof include aliphatic diamines such as 1,1-metaxylylenediamine, 1,3-propanediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine and the like;
Examples of alicyclic diamines include 1,4-diaminocyclohexane, 4,4′-methylenebis (cyclohexylamine), 1,3-bis (aminomethyl) cyclohexane and the like;

Examples of aromatic diamines include p-phenylenediamine, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenyl sulfide, 1,5-diaminonaphthalene, 2,2′-dimethyl-4,4′-diaminobiphenyl, 4,4′-diamino-2,2′-bis (trifluoromethyl) biphenyl, 2,7-diaminofluorene, 4,4′-diaminodiphenyl ether, 2,2-bis [4- (4-aminophenoxy) phenyl ] Propane, 9,9-bis (4-aminophenyl) fluorene, 2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane, 2,2-bis (4-aminophenyl) hexafluoropropane 4,4 ′-(p-phenylenediisopropylidene) bisaniline,

4,4 ′-(m-phenylenediisopropylidene) bisaniline, 1,4-bis (4-aminophenoxy) benzene, 4,4′-bis (4-aminophenoxy) biphenyl, 2,6-diaminopyridine, 3 , 4-diaminopyridine, 2,4-diaminopyrimidine, 3,6-diaminoacridine, 3,6-diaminocarbazole, N-methyl-3,6-diaminocarbazole, N-ethyl-3,6-diaminocarbazole, N -Phenyl-3,6-diaminocarbazole, N, N'-bis (4-aminophenyl) -benzidine, N, N'-bis (4-aminophenyl) -N, N'-dimethylbenzidine, 1,4- Bis- (4-aminophenyl) -piperazine, 3,5-diaminobenzoic acid, dodecanoxy-2,4-diaminobenzene, tetradecanoxy 2,4-diaminobenzene, Pentadekanokishi 2,4-diaminobenzene, Hekisadekanokishi 2,4-diaminobenzene,

Octadecanoxy-2,4-diaminobenzene, dodecanoxy-2,5-diaminobenzene, tetradecanoxy-2,5-diaminobenzene, pentadecanoxy-2,5-diaminobenzene, hexadecanoxy-2,5-diaminobenzene, octadecanoxy-2,5 -Diaminobenzene, cholestanyloxy-3,5-diaminobenzene, cholestenyloxy-3,5-diaminobenzene, cholestanyloxy-2,4-diaminobenzene, cholestenyloxy-2,4-diaminobenzene, 3, Cholestanyl 5-diaminobenzoate, cholestenyl 3,5-diaminobenzoate, lanostannyl 3,5-diaminobenzoate, 3,6-bis (4-aminobenzoyloxy) cholestane, 3,6-bis (4-aminophenoxy) Colestan, 4- ( '-Trifluoromethoxybenzoyloxy) cyclohexyl-3,5-diaminobenzoate, 4- (4'-trifluoromethylbenzoyloxy) cyclohexyl-3,5-diaminobenzoate, 1,1-bis (4-(( Aminophenyl) methyl) phenyl) -4-butylcyclohexane,

1,1-bis (4-((aminophenyl) methyl) phenyl) -4-heptylcyclohexane, 1,1-bis (4-((aminophenoxy) methyl) phenyl) -4-heptylcyclohexane, 1,1- Bis (4-((aminophenyl) methyl) phenyl) -4- (4-heptylcyclohexyl) cyclohexane and the following formula (A-1)

（式（Ａ−１）中、Ｘ^Ｉは炭素数１〜３のアルキル基、^＊−Ｏ−、^＊−ＣＯＯ−または^＊−ＯＣＯ−（ただし、「＊」を付した結合手がジアミノフェニル基と結合する。）であり、ａは０または１であり、ｂは０〜２の整数であり、ｃは１〜２０の整数である。）
で表される化合物などを；

(In the formula (A-1), ^{X I} is an alkyl group having 1 to 3 carbon ^atoms, * ^-O-, * -COO- or ^* -OCO- (where bond marked with "*" is diaminophenyl group And a is 0 or 1, b is an integer of 0 to 2, and c is an integer of 1 to 20.)
A compound represented by:

Examples of the diaminoorganosiloxane include 1,3-bis (3-aminopropyl) -tetramethyldisiloxane, respectively.
The diamine described in Japanese Patent Application No. 2009-157556 can be used.

The ^{X I} in the above formula (A-1) an alkyl group having 1 to 3 carbon ^atoms, * -O- or ^* -COO- (provided that a bond marked with "*" is bonded to the diamino phenyl group.) In Preferably there is. Specific examples of the group C _c H _{2c + 1} — include, for example, methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, n -Nonyl group, n-decyl group, n-dodecyl group, n-tridecyl group, n-tetradecyl group, n-pentadecyl group, n-hexadecyl group, n-heptadecyl group, n-octadecyl group, n-nonadecyl group, n -An eicosyl group etc. can be mentioned. The two amino groups in the diaminophenyl group are preferably in the 2,4-position or 3,5-position with respect to the other groups.
Specific examples of the compound represented by the above formula (A-1) include, for example, the following formulas (A-1-1) to (A-1-4):

And the like, 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 dimian used for synthesizing the polyamic acid A in the present invention includes a diamine having the photoreactive structure, and may optionally further include at least one other diamine.
The diamine diamine having a photoreactive structure used for synthesizing the polyamic acid A in the present invention preferably contains 50 to 99 mol%, particularly 80 to 95 mol%, based on the total diamine. preferable.

[Molecular weight regulator]
In synthesizing the polyamic acid A, a terminal-modified polymer may be synthesized using an appropriate molecular weight regulator together with the tetracarboxylic dianhydride and dimian as described above. By using such a terminal-modified polymer, the coating property (printability) of the liquid crystal aligning agent can be improved without impairing the effects of the present invention.
Examples of the molecular weight regulator include acid monoanhydrides, monoamine compounds, monoisocyanate compounds, and the like.

Specific examples of these acid monoanhydrides include maleic anhydride, phthalic anhydride, itaconic anhydride, n-decylsuccinic anhydride, n-dodecylsuccinic anhydride, n-tetradecylsuccinic acid. Nic acid anhydride, n-hexadecyl succinic acid anhydride, etc .;
Examples of monoamine compounds include aniline, cyclohexylamine, n-butylamine, n-pentylamine, n-hexylamine, n-heptylamine, and n-octylamine;
Examples of the monoisocyanate compound include phenyl isocyanate and naphthyl isocyanate.
The use ratio of the molecular weight regulator is preferably 20 parts by weight or less, and more preferably 10 parts by weight or less with respect to 100 parts by weight of the total of the tetracarboxylic dianhydride and diamine used.

<Synthesis of polyamic acid A>
The ratio of the tetracarboxylic dianhydride and the diamine used in the synthesis reaction of the polyamic acid A is such that the acid anhydride group of the tetracarboxylic dianhydride is 0.2 to 1 equivalent to 1 equivalent of the amino group of the diamine. A ratio of 2 equivalents is preferable, and a ratio of 0.3 to 1.2 equivalents is more preferable.
The polyamic acid synthesis reaction is preferably performed in an organic solvent, preferably at −20 ° C. to 150 ° C., more preferably at 0 to 100 ° C., preferably 0.1 to 120 hours, more preferably 0.5 to 48 hours. Done.
Here, examples of the organic solvent include N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, dimethylsulfoxide, γ-butyrolactone, tetramethylurea, hexamethylphosphortriamide and the like. Protic polar solvents; mention may be made of phenolic solvents such as m-cresol, xylenol, phenol, halogenated phenol. The amount (a) of the organic solvent used is such that the total amount (b) of tetracarboxylic dianhydride and diamine is 0.1 to 50% by weight based on the total amount (a + b) of the reaction solution. It is preferable.
As described above, a reaction solution obtained by dissolving polyamic acid is obtained.
This reaction solution may be used as it is for the preparation of the liquid crystal aligning agent, may be used for the preparation of the liquid crystal aligning agent after isolating the polyamic acid contained in the reaction solution, or the isolated polyamic acid was purified. You may use for preparation of a liquid crystal aligning agent.

[Polyamic acid B]
Polyamic acid B includes at least one tetracarboxylic dianhydride selected from the group consisting of 1,2,3,4-cyclobutanetetracarboxylic dianhydride and pyromellitic dianhydride, and 2,2′- It is obtained by reacting at least one diamine selected from the group consisting of dimethyl-4,4′-diaminobiphenyl, p-phenylenediamine, 4,4′-diaminodiphenylmethane, and 4,4′-diaminodiphenyl ether. is there.

In order to synthesize the polyamic acid B, a tetracarboxylic dianhydride and a diamine other than the specific tetracarboxylic dianhydride and diamine can be used in combination. Examples of other diamines that can be used here include those described above as tetracarboxylic dianhydrides and diamines used to synthesize polyamic acid A (however, diamines having a photoreactive structure are not included). The same thing can be mentioned.
The tetracarboxylic dianhydride used to synthesize polyamic acid B is 1,2,3,4-cyclobutanetetracarboxylic dianhydride, pyromellitic dianhydride, and all tetracarboxylic dianhydrides used. The content is preferably 50 mol% or more, more preferably 80 mol% or more, relative to the product.
The diamine used for synthesizing the polyamic acid B is 2,2′-dimethyl-4,4′-diaminobiphenyl, p-phenylenediamine, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenyl ether, The content is preferably 50 mol% or more, more preferably 80 mol% or more, based on the total diamine used.
Polyamic acid B can be synthesized in the same manner as polyamic acid A.

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 total of the polyamic acid A and the polyamic acid B. If the use ratio 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 inferior. There is a case.

<Other ingredients>
The liquid crystal alignment film of the present invention contains the specific polymer as described above as an essential component, but may contain other components as necessary. Examples of such other components include a polymer other than the specific polymer (hereinafter referred to as “other polymer”) and a compound having at least one epoxy group in the molecule (hereinafter referred to as “epoxy compound”). And functional silane compounds.

[Other polymers]
These other polymers can be used to improve solution and electrical properties. Such other polymer is a polymer other than the specific polymer as described above, and polyamic acid other than polyamic acid A and polyamic acid B (hereinafter referred to as “other polyamic acid”) and polyamic acid are dehydrated and cyclized. And polyimide, polyamic acid ester, polyester, polyamide, polysiloxane, cellulose derivative, polyacetal, polystyrene derivative, poly (styrene-phenylmaleimide) derivative, poly (meth) acrylate, and the like. Of these, other polyamic acids are preferred.

[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, and 1,6-hexane. Diol diglycidyl ether, glycerin diglycidyl ether, 2,2-dibromoneopentyl glycol diglycidyl ether, 1,3,5,6-tetraglycidyl-2,4-hexanediol, N, N, N ′, N′— Tetraglycidyl-m-xylenediamine, 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, N, N, N ′, N′-tetraglycidyl-4,4′-diame Diphenylmethane, N, N-diglycidyl - benzylamine, N, N-diglycidyl - such as aminomethyl cyclohexane may be mentioned as preferred. 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 with respect to 100 parts by weight of the total amount of the polymer.

[Functional silane compounds]
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-ureidopropyltriethoxysilane, N-ethoxycarbonyl-3-aminopropyl Trimethoxysilane, N-ethoxycarbonyl-3-aminopropyltriethoxysilane, N-triethoxysilylpropyltriethylenetriamine, N-trimethoxysilylpropyltriethylenetriamine,

10-trimethoxysilyl-1,4,7-triazadecane, 10-triethoxysilyl-1,4,7-triazadecane, 9-trimethoxysilyl-3,6-diazanonyl acetate, 9-triethoxysilyl-3 , 6-diazanonyl acetate, N-benzyl-3-aminopropyltrimethoxysilane, N-benzyl-3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, N-phenyl-3- Examples thereof include aminopropyltriethoxysilane, N-bis (oxyethylene) -3-aminopropyltrimethoxysilane, N-bis (oxyethylene) -3-aminopropyltriethoxysilane, 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 with respect to 100 parts by weight of the total amount of the polymer.

<Liquid crystal aligning agent>
The liquid crystal aligning agent of the present invention is constituted by dissolving the specific polymer as described above and other additives optionally blended as required, preferably dissolved in an organic solvent.
As an organic solvent which can be used for the liquid crystal aligning agent of this invention, the solvent illustrated as what is used for the synthesis reaction of a polyamic acid can be mentioned. In addition, an organic solvent believed to be a poor solvent for conventional polyamic acid and polyimide can be appropriately selected and used in combination. Preferred examples of such organic solvents include N-methyl-2-pyrrolidone, γ-butyrolactone, γ-butyrolactam, N, N-dimethylformamide, N, N-dimethylacetamide, 4-hydroxy-4-methyl-2- Pentanone, ethylene glycol monomethyl ether, butyl lactate, butyl acetate, methyl methoxypropionate, ethyl ethoxypropionate, ethylene glycol methyl ether, ethylene glycol ethyl ether,

Ethylene glycol-n-propyl ether, ethylene glycol-i-propyl ether, ethylene glycol-n-butyl ether (butyl cellosolve), ethylene glycol dimethyl ether, ethylene glycol ethyl ether acetate, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl Ether, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diisobutyl ketone, isoamyl propionate, isoamyl isobutyrate, diisopentyl ether, cyclohexanone, diacetone alcohol, ethyl carbitol, ethoxyethyl propionate, Chill cellosolve acetate, carbitol acetate, and propylene carbonate. These can be used alone or in admixture of two or more.

  The solid content concentration of the liquid crystal aligning agent of the present invention (the ratio of the total weight of components excluding the organic solvent in the liquid crystal aligning agent to the total weight of the liquid crystal aligning agent) is appropriately selected in consideration of viscosity, volatility, etc. However, it is preferably in the range of 1 to 10% by weight. That is, when the liquid crystal aligning agent of the present invention is applied to the substrate surface and the organic solvent is removed to form a coating film that becomes a liquid crystal aligning film, the solid content concentration is less than 1% by weight. The film thickness of this coating film may be too small to obtain a good liquid crystal alignment film. On the other hand, if the solid content concentration exceeds 10% by weight, the film thickness of the coating film will be excessive. Similarly, it may be difficult to obtain a good liquid crystal alignment film, and the viscosity of the liquid crystal aligning agent may increase, resulting in poor coating characteristics.

  The particularly preferable solid content concentration range varies depending on the method used when applying the liquid crystal aligning agent to the substrate. For example, when the spinner method is used, the range of 1.5 to 4.5% by weight is particularly preferable. When using the printing method, the solid content concentration is preferably 3 to 9% by weight.

<Method for forming liquid crystal alignment film>
The liquid crystal aligning agent of this invention can be used conveniently in order to form a liquid crystal aligning film by the photo-alignment method.
As a method for forming a liquid crystal alignment film, for example, a liquid crystal aligning agent is applied onto a substrate to form a coating film, and the coating film is irradiated with polarized or non-polarized ultraviolet rays obliquely with respect to the coating film surface. Or a method of imparting liquid crystal alignment ability to the coating film by irradiating polarized ultraviolet rays from a direction perpendicular to the coating film surface.

First, the liquid crystal aligning agent of this invention is apply | coated to the transparent conductive film side of the board | substrate with which the pattern-shaped transparent conductive film was provided, for example by appropriate coating methods, such as a roll coater method, a spinner method, a printing method, an inkjet method. . After coating, the coated surface is preheated (prebaked) and then baked (postbaked) to form a coating film. The pre-bake conditions are, for example, 0.1 to 5 minutes at 40 to 120 ° C., and the post-bake conditions are preferably 120 to 300 ° C., more preferably 150 to 250 ° C., preferably 5 to 200 minutes, more preferably 10 to 100 minutes. The film thickness of the coating film after post-baking is preferably 0.001-1 μm, more preferably 0.005-0.5 μm.
Examples of the substrate include glass such as float glass and soda glass; and a transparent substrate made of plastic such as polyethylene terephthalate, polybutylene terephthalate, polyethersulfone, and polycarbonate.

As the transparent conductive film, a NESA film made of SnO _{2 or} an ITO film made of In ₂ O ₃ —SnO ₂ can be used. For patterning these transparent conductive films, a photo-etching method or a method using a mask when forming the transparent conductive film is used.
When applying the liquid crystal aligning agent, in order to further improve the adhesion between the substrate or the transparent conductive film and the coating film, a functional silane compound, titanate compound or the like is previously applied on the substrate and the transparent conductive film. May be.

  Next, the coating film becomes a liquid crystal alignment film by imparting liquid crystal alignment ability by irradiating the coating film with polarized or non-polarized ultraviolet rays. Here, as radiation, for example, ultraviolet rays and visible light containing light having a wavelength of 150 to 800 nm can be used, but ultraviolet rays containing 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 a direction perpendicular to the coating film surface or from an oblique direction for providing a pretilt angle. On the other hand, when irradiating non-polarized radiation, it is necessary to perform irradiation from an oblique direction with respect to the coating surface.

  As a light source for 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, an excimer laser, or the like can be used. The ultraviolet rays in the preferable wavelength region can be obtained by means of using the light source in combination with, for example, a filter or a diffraction grating.

The irradiation dose of radiation, preferably less than 1 J / ^{m 2} or more 10,000 J / ^{m 2,} more preferably from 10~3,000J / ^{m 2.} In addition, when providing the liquid crystal aligning ability by the photo-alignment method to the coating film formed from the conventionally known liquid crystal aligning agent, the irradiation dose of 10,000 J / m < ² > or more was required. However, using the liquid crystal aligning agent of the present invention, the radiation dose at the time of photo-alignment method is 3,000 J / ^{m 2} or less, further 1,000 J / ^{m 2} or less, even more was at 300 J / ^{m 2} or less good Liquid crystal alignment ability can be imparted, which contributes to the reduction of the manufacturing cost of the liquid crystal display element.

<Method for manufacturing liquid crystal display element>
The liquid crystal display element of this invention comprises the liquid crystal aligning film formed from the liquid crystal aligning agent of this invention. The liquid crystal display element of this invention can be manufactured as follows, for example.
A liquid crystal cell is manufactured by preparing two substrates on which a liquid crystal alignment film is formed as described above, and disposing a liquid crystal between the two substrates. In order to manufacture a liquid crystal cell, the following two methods are mentioned, for example.

The first method is a conventionally known method. First, two substrates are arranged to face each other through a gap (cell gap) so that the respective liquid crystal alignment films are opposed to each other, and the peripheral portions of the two substrates are bonded using a sealant, and the substrate surface and the sealant are bonded. A liquid crystal cell can be manufactured by injecting and filling liquid crystal into the cell gap partitioned by the step, and then sealing the injection hole.
The second method is a method called an ODF (One Drop Fill) method. For example, an ultraviolet light curable sealant is applied to a predetermined location on one of the two substrates on which the liquid crystal alignment film is formed, and liquid crystal is dropped on the liquid crystal alignment film surface. The other substrate is bonded so as to face each other, and then the entire surface of the substrate is irradiated with ultraviolet light to cure the sealant, whereby a liquid crystal cell can be manufactured.

In any case, it is desirable to remove the flow alignment at the time of filling the liquid crystal by heating the liquid crystal cell to a temperature at which the liquid crystal used has an isotropic phase and then gradually cooling it to room temperature.
And the liquid crystal display element of this invention can be obtained by bonding a polarizing plate on the outer surface of a liquid crystal cell. Here, when the liquid crystal alignment film is horizontally aligned, the angle formed by the polarization direction of the irradiated linearly polarized radiation and the angle between each substrate and the polarizing plate are adjusted on the two substrates on which the liquid crystal alignment film is formed. By doing so, a liquid crystal display element having a 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, the cell is configured so that the directions of easy alignment axes of the two substrates on which the liquid crystal alignment film is formed are parallel, A liquid crystal display element having a vertical alignment type liquid crystal cell can be obtained by bonding so that the polarization direction forms an angle of 45 ° with the easy alignment axis.

As the sealing agent, for example, an aluminum oxide sphere as a spacer and an epoxy resin containing a curing agent can be used.
As the liquid crystal, for example, nematic liquid crystal or smectic liquid crystal can be preferably used.
In the case of a TN type liquid crystal cell or an STN type liquid crystal cell, a nematic type liquid crystal having positive dielectric anisotropy is preferable. For example, a biphenyl liquid crystal, a phenylcyclohexane liquid crystal, an ester liquid crystal, a terphenyl liquid crystal, a biphenylcyclohexane liquid crystal, Pyrimidine liquid crystals, dioxane liquid crystals, bicyclooctane liquid crystals, cubane liquid crystals and the like are used. In addition, cholesteric liquid crystals such as cholesteryl chloride, cholesteryl nonate, cholesteryl carbonate; chiral agents such as those sold under the trade names “C-15” and “CB-15” (manufactured by Merck); p- A ferroelectric liquid crystal such as decyloxybenzylidene-p-amino-2-methylbutylcinnamate may be further added and used.

On the other hand, in the case of a vertical alignment type liquid crystal cell, a nematic liquid crystal having negative dielectric anisotropy is preferable. For example, dicyanobenzene liquid crystal, pyridazine liquid crystal, Schiff base liquid crystal, azoxy liquid crystal, biphenyl liquid crystal, phenyl cyclohexane. System liquid crystal or the like is used.
The polarizing plate used outside the liquid crystal cell is composed of a polarizing film called “H film” in which polyvinyl alcohol is stretched and oriented while absorbing iodine and sandwiched between cellulose acetate protective films, or the H film itself. A polarizing plate etc. can be mentioned.
The liquid crystal display element of the present invention thus produced has excellent display performance and does not deteriorate even when used for a long time.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.
In the following synthesis examples, the polymer solution viscosity and the polyimide imidation rate were evaluated by the following methods.

[Solution viscosity of polymer]
The solution viscosity (mPa · s) of the polymer was measured at 25 ° C. using an E-type viscometer for each polymer solution.
[Imidation rate of polyimide]
A small amount of the solution containing the polyimide obtained in each synthesis example was collected and poured into pure water, and the resulting precipitate was collected by filtration to isolate the polyimide. The polyimide was sufficiently dried at room temperature under reduced pressure, dissolved in deuterated dimethyl sulfoxide, and calculated from the following formula (1) from ¹ H-NMR measured at room temperature using tetramethylsilane as a reference substance.
Imidation rate (%) = (1-A ¹ / A ² × α) × 100 (1)
(In Formula (1), A ¹ is a peak area derived from protons of NH groups appearing in the vicinity of 10 ppm, A ² is a peak area derived from other protons, and α is NH in a polyimide precursor (polyamic acid). This is the ratio of the number of other protons to one proton in the group.

<Polymer synthesis examples and comparative synthesis examples>
[Synthesis of polyamic acid A]
Synthesis Examples 1 to 31
In 135 g of N-methyl-2-pyrrolidone, the diamine and tetracarboxylic dianhydride of the type and amount shown in Table 1 were added and dissolved in this order, and the total weight of the diamine and tetracarboxylic dianhydride was Each solution containing 10% by weight of polyamic acid (PA-1) to (PA-31) was prepared by reacting at 60 ° C. for 6 hours with respect to the total weight of the reaction solution. 150 g was obtained respectively. The viscosities of the solutions obtained here are also shown in Table 1.

[Synthesis of polyimide]
Comparative Synthesis Examples 1-15
In 135 g of N-methyl-2-pyrrolidone, diamine and tetracarboxylic dianhydride of the types and amounts shown in Table 2 were added in this order and dissolved, and the total weight of diamine and tetracarboxylic dianhydride was A solution of 10% by weight with respect to the total weight of the reaction solution was reacted at 60 ° C. for 6 hours to obtain 150 g of a solution containing 10% by weight of polyamic acid. The viscosities of the solutions obtained here are also shown in Table 1.

Next, pyridine and acetic anhydride in the amounts shown in Table 2 were added to each of the solutions containing each of these polyamic acids, and a dehydration ring closure reaction was performed at 110 ° C. for 4 hours. After the dehydration ring-closing reaction, the solvent in the system was replaced with new N-methyl-2-pyrrolidone (in this operation, pyridine and acetic anhydride used for the dehydration ring-closing reaction were removed from the system) to obtain polyimide. A solution containing 15% by weight of (RPI-1) to (RPI-15) was obtained. The yield of each solution, a small amount of each solution was sampled, N-methyl-2-pyrrolidone was added and diluted to 10% by weight, and the measured solution viscosity and imidation ratio of each polyimide are shown in Table 2. Also shown.

In Tables 1 and 2, the abbreviations for diamine and tetracarboxylic dianhydride have the following meanings, respectively.
[Diamine]
Second diamine d-1: Compound represented by the above formula (A-2-1-1) d-2: Compound represented by the above formula (A-2-1-2) d-3: The above formula Compound represented by (A-2-1-3) d-4: Compound represented by the above formula (A-2-1-4) d-5: In the above formula (A-2-2-1) Compound 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: The above formula Compound represented by (A-2-1-7) d-9: Compound represented by the above formula (A-2-1-8) d-10: In the above formula (A-2-1-9) Compound 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: The above formula Compound represented by (A-2-1-12) d- 4: Compound represented by the above formula (A-2-1-13) First diamine d-15: Cholestanyl 3,5-diaminobenzoate d-16: 1-cholestanyloxy-2,4-diaminobenzene d-17: cholesteryl 3,5-diaminobenzoate

[Tetracarboxylic dianhydride]
t-1: 1,3,3a, 4,5,9b-hexahydro-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] furan-1,3-dione,
t-2: 1,2,3,4-cyclobutanetetracarboxylic dianhydride t-3: 2,3,5-tricarboxycyclopentylacetic dianhydride [synthesis of polyamic acid B]
Synthesis example OPA-1
1,2,3,4-Cyclobutanetetracarboxylic dianhydride 98 g (0.50 mol) and pyromellitic dianhydride 110 g (0.50 mol) as tetracarboxylic dianhydride and 4,4 ′ as diamine -200 g (1.0 mol) of diaminodiphenylmethane was dissolved in 2,100 g of a mixed solvent consisting of 230 g of N-methyl-2-pyrrolidone and γ-butyrolactone, reacted at 40 ° C. for 3 hours, γ-butyrolactone 1, By adding 350 g, a solution containing 10% by weight of polyamic acid (OPA-1) was obtained. The solution viscosity of this polyamic acid solution was 125 mPa · s.

Synthesis example OPA-2
200 g (1.0 mol) of 1,2,3,4-cyclobutanetetracarboxylic dianhydride as tetracarboxylic dianhydride and 210 g of 2,2′-dimethyl-4,4′-diaminobiphenyl as diamine (1. 0 mol) is dissolved in a mixed solvent consisting of 370 g of N-methyl-2-pyrrolidone and 3,300 g of γ-butyrolactone, and reacted at 40 ° C. for 3 hours to contain 10% by weight of polyamic acid (OPA-2) A solution was obtained. The solution viscosity of this polyamic acid solution was 160 mPa · s.

[Synthesis of polyimide]
Synthesis example OPI-3
110 g (0.50 mol) of 2,3,5-tricarboxycyclopentyl acetic acid dianhydride as tetracarboxylic dianhydride, 43 g (0.40 mol) and 3 (3,5-diamino) of p-phenylenediamine as diamine compounds Benzoyloxy) cholestane 52 g (0.10 mol) was dissolved in 830 g of N-methyl-2-pyrrolidone and reacted at 60 ° C. for 6 hours. A small amount of the obtained polyamic acid solution was taken, N-methyl-2-pyrrolidone was added, and the viscosity was measured with a solution having a solid content concentration of 10%. As a result, it was 60 mPa · s. Next, 1900 g of NMP was added to the obtained polyamic acid solution, 40 g of pyridine and 51 g of acetic anhydride were added, and dehydration ring closure was performed at 110 ° C. for 4 hours. After the imidization reaction, the solvent in the system was replaced with new N-methyl-2-pyrrolidone (pyridine and acetic anhydride used for the imidization reaction were removed from the system in this operation), and the imidization rate was about A solution containing about 15% by weight of 50% polyimide (OPI-3) was obtained. A small amount of the obtained polyimide solution was taken, N-methyl-2-pyrrolidone was added, and the solution viscosity measured as a solution having a polyimide concentration of 10% by weight was 47 mPa · s.

Example 1
I. Preparation of liquid crystal aligning agent As a polymer, a solution containing the polyamic acid (PA-1) obtained in Synthesis Example 1 and a solution containing the polyamic acid (OPA-2) obtained in Synthesis Example OPA-2, Polyamic acid (PA-1): Polyamic acid (OPA-2) = 20: 80 (weight ratio) was mixed so that γ-butyrolactone (BL), N-methyl-2-pyrrolidone (NMP) and Diethylene glycol diethyl ether (DEDG) was added and stirred well 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. A liquid crystal aligning agent was prepared by filtering this solution using a filter having a pore diameter of 1 μm.

III. Manufacture of liquid crystal cell The liquid crystal aligning agent prepared above is 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 (prebaked) on a hot plate at 80 ° C. for 1 minute to remove the solvent. After the removal, the film was heated (post-baked) for 40 minutes in an oven at 200 ° C. in which the interior of the chamber was replaced with nitrogen to form a coating film having an average film thickness of 1,000 mm. Next, the surface of the coating film was irradiated with polarized ultraviolet rays 200 J / m ² containing an emission line having a wavelength of 313 nm using a Hg—Xe lamp and a Grand Taylor prism from a direction inclined by 40 ° from the normal line of the coating film to obtain liquid crystal orientation. To give a liquid crystal alignment film. The same operation was repeated to manufacture a pair (two) of substrates having a liquid crystal alignment film.
After applying an epoxy resin adhesive containing aluminum oxide spheres having a diameter of 5.5 μm to the outer periphery of the surface having one liquid crystal alignment film of the above substrates by screen printing, the liquid crystal alignment film surfaces of the pair of substrates are arranged to face each other. The adhesive was pressure-bonded so that the projection direction of the ultraviolet optical axis of each substrate onto the substrate surface was antiparallel, and the adhesive was thermally cured at 150 ° C. for 1 hour. Next, after filling the gap between the substrates from the liquid crystal injection port with negative type liquid crystal (MLC-6608, manufactured by Merck), the liquid crystal injection port was sealed with an epoxy adhesive. Furthermore, in order to remove the flow alignment at the time of liquid crystal injection, this was heated to 120 ° C. and then gradually cooled to room temperature to produce a liquid crystal cell.
The liquid crystal cell was evaluated for liquid crystal orientation, pretilt angle and voltage holding ratio by the following methods. The evaluation results are shown in Table 3.

IV. Evaluation of liquid crystal cell (1) Liquid crystal alignment The liquid crystal cell produced above was observed with a polarizing microscope for the presence or absence of an abnormal domain when a voltage of 5 V was turned ON / OFF (applied / released) at 25 ° C. The case where there was no liquid crystal was evaluated as “good” liquid crystal alignment.
(2) Voltage holding ratio After applying a voltage of 5 V to the liquid crystal cell manufactured above at a temperature of 70 ° C. with an application time of 60 microseconds and a span of 167 milliseconds, the voltage holding ratio after 167 milliseconds from the release of application Was measured by “VHR-1” manufactured by Toyo Corporation.

(3) Evaluation of Pretilt Light Resistance The method described in Non-Patent Document 2 (T. J. Scheffer et. Al. J. Appl. Phys. Vo. 19, p2013 (1980)) for the liquid crystal cell produced above. The pretilt angle was measured by the crystal rotation method using He—Ne laser light (initial pretilt angle (θ _IN )). Next, the liquid crystal cell was irradiated with a weather meter using a carbon arc as a light source for 5,000 hours, and the pretilt angle was measured again by the same method as above (post-irradiation pretilt angle (θ _AF )).

(4) Residual DC voltage The liquid crystal cell manufactured above was applied with a 30 Hz, 3 V rectangular wave with 5 V DC superimposed at an ambient temperature of 60 ° C. for 2 hours, and remained in the liquid crystal cell immediately after the DC voltage was turned off. The obtained voltage (residual DC voltage) was determined by a flicker-erasing method. This value serves as an index of afterimage characteristics. When this value is approximately 150 mV or less, the afterimage characteristics are good, and when it is approximately 50 mV or less, it is particularly excellent.
Examples 2-34 and Comparative Examples 1-17
In Example 1 above, a liquid crystal aligning agent was prepared in the same manner as in Example 1 except that the types and amounts of polymers shown in Tables 3 and 4 were used as the polymers, and a liquid crystal cell was produced. And evaluated.
The evaluation results are shown in Tables 3 and 4.

Example 35
V. Preparation of Liquid Crystal Alignment Agent A solution containing the polyamic acid (PA-1) obtained in Synthesis Example 1 and a solution containing the polyamic acid (OPA-2) obtained in Synthesis Example OPA-2 were prepared as (PA-1). ): (OPA-2) = 20: 80 (weight ratio), and γ-butyrolactone (BL), N-methyl-2-pyrrolidone (NMP) and butyl cellosolve (BC) are added to the mixture. To give a solution having a solvent composition of BL: NMP: BC = 71: 17: 12 (weight ratio) and a solid content concentration of 6.0% by weight. A liquid crystal aligning agent was prepared by filtering this solution using a filter having a pore diameter of 1 μm.
VI. Evaluation of printability About the liquid crystal aligning agent prepared above, it apply | coated to the transparent electrode surface of the glass substrate with a transparent electrode which consists of an ITO film | membrane using a liquid crystal aligning film printer (made by Nissha Printing Co., Ltd.), and 80 degreeC After removing the solvent by heating (pre-baking) for 1 minute on a hot plate, it was heated (post-baking) for 10 minutes on a hot plate at 200 ° C. to form a coating film having an average film thickness of 600 mm. When this coating film was observed with a microscope with a magnification of 20 times to check for the presence of printing unevenness and pinholes, neither printing unevenness nor pinholes were observed, and the printability was good.

Examples 36-65
Example 35 except that polyamic acids (PA-2) to (PA-31) obtained in Synthesis Examples 2-31 were used instead of the polyamic acid (PA-1) obtained in Synthesis Example 1 above. Similarly, when the liquid crystal aligning agent was prepared and printability was evaluated, neither printing nonuniformity nor a pinhole was observed, and printability was favorable.

Comparative Examples 18-32
Example 35 except that the polyamic acid (PA-1) obtained in Synthesis Example 1 was used and polyimides (RPI-1) to (RPI-15) obtained in Comparative Synthesis Examples 1 to 15 were used. Similarly, when the liquid crystal aligning agent was prepared and printability was evaluated, the printing nonuniformity and the pinhole were observed and printability was unsatisfactory.

Comparative Example 33
Instead of the polyamic acid (PA-1) obtained in Synthesis Example 1, the polyamic acid (PA-16) obtained in Synthesis Example 16 was used, and the polyamic acid (OPA-) obtained in Synthesis Example OPA-2 was used. In place of 2), a liquid crystal aligning agent was prepared in the same manner as in Example 35 except that the polyimide (OPI-3) obtained in Synthesis Example OPI-3 was used. Unevenness and pinholes were observed, and the printability was poor.

Claims (6)

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

(In 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. Yes, e and f are each an integer of 0 to 4, and “+” indicates a bond.
The liquid crystal aligning agent of Claim 1 which is a structure represented by these. The structure represented by the above formula (A-2) has 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 are respectively synonymous with those in the formula (A-2),
R ^I and R ^II are each an alkyl group having 1 to 40 carbon atoms in which some or all of the hydrogen atoms may be substituted with fluorine atoms,
X ^II and X ^III are respectively —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 is a methylene group, an arylene group, a divalent alicyclic group, —Si (CH ₃ ) ₂ —, —CH═CH— or —C≡C—, respectively, provided that R ^III has a hydrogen atom One or more of these 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 from 0 to 2,
When a plurality of X ^II and R ^III are present, they may be the same as or different from each other;
j is 0 or 1, and “+” indicates a bond. )
The liquid crystal aligning agent of Claim 3 which is at least 1 type of structure selected from the structure represented by each of these.   A liquid crystal alignment film formed from the liquid crystal aligning agent according to claim 1. A liquid crystal display element comprising the liquid crystal alignment film according to claim 5.