JP5569441B2 - Liquid crystal alignment agent, liquid crystal alignment film, and liquid crystal display element - Google Patents

Description

  The present invention relates to a liquid crystal aligning agent, a liquid crystal aligning film, and a liquid crystal display element, and more specifically, a liquid crystal aligning agent and a liquid crystal aligning film that can be suitably applied to a horizontal alignment type liquid crystal display element (horizontal alignment mode), The present invention relates to a liquid crystal display element.

  Conventionally, horizontal alignment type liquid crystal display elements such as a twisted nematic display mode (TN mode), a horizontal electric field display mode (IPS mode), and a fringe field switching mode (FFS mode) are known as one of liquid crystal display elements. In this liquid crystal display element, liquid crystal molecules are sealed between a pair of opposed substrates, liquid crystal molecules are aligned parallel to the substrate surface (horizontal alignment), and a voltage is applied to the liquid crystal molecules to align the liquid crystal molecules. To change. Thereby, in the liquid crystal display element, the optical switching function by the liquid crystal molecules is expressed.

  In the liquid crystal display element, alignment control of liquid crystal molecules is performed by a liquid crystal alignment film. In general, the liquid crystal alignment film is obtained by applying a liquid crystal aligning agent containing polyimide or polyamic acid to a substrate, baking the film, and rubbing the fired thin film surface in a certain direction with a cloth so-called rubbing treatment. be able to.

  In order to improve the display performance of the liquid crystal display element, it is necessary to align liquid crystal molecules in a specific direction when no voltage is applied, and various liquid crystal aligning agents have been proposed to achieve this (for example, Patent Documents 1 to 3). 3). Patent Document 1 discloses a liquid crystal alignment method using polyimide obtained by polymerization reaction of pyromellitic dianhydride (PMDA) and diamine. Aromatic polyimide produced using PMDA has high uniaxial orientation due to rubbing treatment and good liquid crystal orientation due to interaction with the benzene ring of liquid crystal molecules. It is said.

  Patent Documents 2 and 3 disclose a liquid crystal aligning agent containing a polyimide obtained by polymerization of an acid dianhydride having an alicyclic structure such as cyclobutanetetracarboxylic acid anhydride (CB) and a diamine. Yes. In this alicyclic polyimide, etc., compared with the aromatic polyimide as in Patent Document 1, (1) the light transmittance of the liquid crystal alignment film is high because there is no absorption in the visible light region, and (2) the rubbing resistance is good. (3) It is easy to adjust the viscosity in a solution state.

JP-A-57-128318 Japanese Patent No. 4052308 JP 2010-156934 A

  By the way, in the liquid crystal alignment film formed of alicyclic polyimide or the like, it has the advantages (1) to (3) as compared with the aromatic polyimide, but when the liquid crystal molecules are injected between the substrates, the liquid crystal molecules Flow orientation that is oriented in the flow direction during injection tends to occur. Therefore, there is a concern that the liquid crystal alignment ability is reduced due to the flow alignment. In addition, when the liquid crystal alignment film is formed from an alicyclic polyimide or the like, a crosslinking agent such as an epoxy compound may be added for the purpose of improving mechanical strength. In some cases, the stretchability may be lowered, and in such a case, it is considered that fluid orientation tends to occur.

  Furthermore, a liquid crystal display element is required to have a high voltage holding ratio in order to improve display quality, and it is necessary to study the voltage holding characteristics of the liquid crystal display element when designing a liquid crystal alignment film. However, as a result of investigation by the present inventor, it was confirmed that when PMDA is used as the acid dianhydride as in Patent Document 1 described above, the liquid crystal orientation is good, but the liquid crystal voltage holding ratio is low. .

  The present invention has been made in view of the above problems, and a liquid crystal aligning agent for obtaining a liquid crystal display element having both excellent liquid crystal alignment properties and voltage holding characteristics, a liquid crystal alignment film formed with the liquid crystal aligning agent, and the liquid crystal A main object is to provide a liquid crystal display device including an alignment film.

  As a result of intensive studies to solve the problems of the prior art as described above, the present inventors have determined that a diamine having a specific structure is at least one of an aliphatic tetracarboxylic dianhydride and an alicyclic tetracarboxylic dianhydride. It is found that the above-mentioned problems can be solved by containing at least one of the polyamic acid obtained by this reaction and the imidized polymer thereof as a polymer component of the liquid crystal aligning agent. It came to be completed. Specifically, the present invention provides the following liquid crystal aligning agent, liquid crystal alignment film, and liquid crystal display element.

  The present invention is a liquid crystal aligning agent containing at least one of a polyamic acid obtained by reacting a tetracarboxylic dianhydride and a diamine and an imidized polymer thereof, wherein the tetracarboxylic dianhydride is, It contains at least one of aliphatic tetracarboxylic dianhydride and alicyclic tetracarboxylic dianhydride, and the diamine contains a compound represented by the following formula (D-1). And

（式中、Ｒ^１〜Ｒ^１０は、Ｒ^１〜Ｒ^５のうちの１つ及びＲ^６〜Ｒ^１０のうちの１つが一級アミノ基であり、残りが、それぞれ独立に、水素原子、フッ素原子、又は炭素数１〜６のアルキル基、アルコキシ基若しくはフルオロアルキル基である。）

(Wherein R ^{1 to} R ¹⁰ are one of R ^{1 to} R ⁵ and one of R ^{6 to} R ¹⁰ are primary amino groups, and the rest are each independently a hydrogen atom or a fluorine atom. Or an alkyl group having 1 to 6 carbon atoms, an alkoxy group, or a fluoroalkyl group.)

  According to the liquid crystal aligning agent of the present invention, even when an aliphatic tetracarboxylic dianhydride or an alicyclic tetracarboxylic dianhydride is included as a tetracarboxylic dianhydride, the flow alignment of liquid crystal molecules can be suppressed. A liquid crystal alignment film can be formed. Moreover, when the liquid crystal aligning film formed with the liquid crystal aligning agent of this invention is used for a liquid crystal display element, a high voltage retention is shown. Therefore, according to the liquid crystal aligning agent of the present invention, it is possible to obtain a liquid crystal display element having a good balance between liquid crystal alignment and voltage holding characteristics.

  In the present invention, as tetracarboxylic dianhydride, a mixture of at least one of the aliphatic tetracarboxylic dianhydride and the alicyclic tetracarboxylic dianhydride and an aromatic tetracarboxylic dianhydride is used. It may be used. In this case, the liquid crystal alignment can be improved as compared with the case where the former is used alone.

  Furthermore, according to this invention, the liquid crystal aligning film formed from the liquid crystal aligning agent as described above, and the liquid crystal display element which comprises the liquid crystal aligning film are provided. Moreover, the polyamic acid obtained by reaction with at least any one of an aliphatic tetracarboxylic dianhydride and an alicyclic tetracarboxylic dianhydride, and the diamine represented by the said Formula (D-1), and its imidation weight A coalescence (polyimide) is provided.

  The liquid crystal aligning agent of this invention contains at least any one of the polyamic acid obtained by making tetracarboxylic dianhydride and diamine react, and its imidized polymer. Hereinafter, the liquid crystal aligning agent of this invention is demonstrated in detail.

<Polyamic acid>
The polyamic acid contained in the liquid crystal aligning agent of this invention can be obtained by making tetracarboxylic dianhydride react with the diamine represented by the said Formula (D-1).

[Tetracarboxylic dianhydride]
The tetracarboxylic dianhydride for synthesizing the polyamic acid in the present invention includes a tetracarboxylic dianhydride having an aliphatic structure (hereinafter also referred to as an aliphatic tetracarboxylic dianhydride), and an alicyclic structure. At least one of tetracarboxylic dianhydrides (hereinafter also referred to as alicyclic tetracarboxylic dianhydrides).

  Here, “aliphatic tetracarboxylic dianhydride” refers to an acid dianhydride obtained by intramolecular dehydration of four carboxyl groups bonded to a saturated hydrocarbon group. However, the aliphatic tetracarboxylic dianhydride does not need to be composed only of a chain structure, and a part thereof may have a cyclic hydrocarbon structure or an aromatic ring structure. The “alicyclic tetracarboxylic dianhydride” refers to an acid dianhydride obtained by intramolecular dehydration of at least two carboxyl groups bonded to the aliphatic ring. However, the alicyclic tetracarboxylic dianhydride does not need to be composed only of an alicyclic structure or a chain structure, and may have an aromatic ring structure in a part thereof.

Specifically, examples of the aliphatic tetracarboxylic dianhydride include 1,2,3,4-butanetetracarboxylic dianhydride. Examples of the alicyclic tetracarboxylic dianhydride include 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentylacetic 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-1,2-dica Boronic acid anhydride, 3,5,6-tricarboxy-2-carboxymethylnorbornane-2: 3,5: 6-dianhydride, bicyclo [3,3,0] octane-2,4,6,8- List tetracarboxylic dianhydride, 4,9-dioxatricyclo [5.3.1.0 ^2,6 ] undecane-3,5,8,10-tetraone, cyclohexanetetracarboxylic dianhydride, etc. Can do. In addition, aliphatic tetracarboxylic dianhydrides and alicyclic tetracarboxylic dianhydrides described in JP 2010-97188 A, other than those described above, can be used.

  As the aliphatic tetracarboxylic dianhydride and alicyclic tetracarboxylic dianhydride used for synthesizing the polyamic acid in the present invention, among these, 1,2,3,4-cyclobutanetetracarboxylic acid diacid is particularly preferable. Anhydride, 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, bicyclo [3,3,0] octane-2,4,6,8-tetracarboxylic dianhydride, cyclohexanetetracarboxylic dianhydride, and 1, , At least one is preferably selected from the group consisting of 3,4-butane tetracarboxylic acid dianhydride. From the viewpoint of further increasing the voltage holding ratio, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, (1S, 2S, 4R, 5R) -cyclohexanetetracarboxylic dianhydride, (1R, 2S, 4S, 5R) -cyclohexanetetracarboxylic dianhydride and at least one selected from the group consisting of 2,3,5-tricarboxycyclopentylacetic acid dianhydride are more preferable, and an epoxy compound as a crosslinking agent was added. From the viewpoint of achieving good liquid crystal alignment, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3,3a, 4,5,9b-hexahydro-5- (tetrahydro- 2,5-dioxo-3-furanyl) -naphtho [1,2-c] furan-1,3-dione and 1,3,3a, 4,5,9b-hex Hydro-8-methyl-5- (tetrahydro-2,5-dioxo-3-furanyl) - naphtho least one and more preferably selected from the group consisting of [1,2-c] furan-1,3-dione. Among these, 1,2,3,4-cyclobutanetetracarboxylic dianhydride is particularly preferable.

  In addition, said aliphatic tetracarboxylic dianhydride and alicyclic tetracarboxylic dianhydride can be used individually by 1 type or in combination of 2 or more types.

  As the tetracarboxylic dianhydride, at least one of the above aliphatic tetracarboxylic dianhydrides and alicyclic tetracarboxylic dianhydrides may be used, but the aliphatic tetracarboxylic dianhydrides and A combination of at least one of alicyclic tetracarboxylic dianhydrides and a tetracarboxylic dianhydride having an aromatic ring structure (aromatic tetracarboxylic dianhydride) may be used. Here, “aromatic tetracarboxylic dianhydride” refers to an acid dianhydride obtained by intramolecular dehydration of four carboxyl groups bonded to the same or different aromatic rings.

  Specific examples of the aromatic tetracarboxylic dianhydride include pyromellitic dianhydride (PMDA), 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 3,3 ′, 4, 4'-benzophenone tetracarboxylic dianhydride, 1,4,5,8-naphthalene tetracarboxylic dianhydride, and other aromatic tetracarboxylic dianhydrides described in JP 2010-97188 A Can do. Preferably, it is PMDA. Since PMDA is excellent in liquid crystal alignment, by combining PMDA with at least one of aliphatic tetracarboxylic dianhydride and alicyclic tetracarboxylic dianhydride, compared to the case where the former is used alone. It is preferable in that the orientation in the liquid crystal alignment film can be improved. On the other hand, when an aliphatic tetracarboxylic acid or an alicyclic tetracarboxylic dianhydride is used alone, the voltage holding ratio can be increased as compared with a mixed system with an aromatic tetracarboxylic dianhydride. preferable.

  When a mixture of aliphatic or alicyclic and aromatic is used as the tetracarboxylic dianhydride, the total amount of the aliphatic or alicyclic tetracarboxylic dianhydride is The amount of tetracarboxylic dianhydride is preferably 10 to 95 mol%, more preferably 30 to 90 mol%, still more preferably 50 to 85 mol%, and particularly preferably 60 to 80 mol%. In this case, the ratio of the aromatic tetracarboxylic dianhydride in the mixed system is preferably 5 to 90 mol%, more preferably 10 to 70 mol%, and more preferably 15 to 50 mol based on the total amount of tetracarboxylic dianhydride. % Is more preferable, and 20-40 mol% is especially preferable. By setting each of the above ranges, both a high voltage holding ratio and excellent liquid crystal orientation can be expressed in a well-balanced manner when the liquid crystal alignment film is formed. Also, the rubbing resistance is good.

[Diamine]
At least a part of the diamine used for synthesizing the polyamic acid in the present invention is a compound represented by the above formula (D-1). In the above formula (D-1), one of R ^{1 to} R ⁵ and one of R ^{6 to} R ¹⁰ are primary amino groups. That is, the compound represented by the formula (D-1) is a diamine in which one primary amino group is bonded to different benzene rings.

Among R ^{1 to} R ¹⁰ , the remainder other than the primary amino group is a hydrogen atom, a fluorine atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group, or a fluoroalkyl group, which may be the same or different. May be. The alkyl group having 1 to 6 carbon atoms may be linear or branched, and specifically includes methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl. Group, sec-butyl group, tert-butyl group, n-pentyl group, isopentyl group, neopentyl group, n-hexyl group, isohexyl group and the like.

  As a C1-C6 fluoroalkyl group, what substituted at least 1 hydrogen atom of the group quoted as said C1-C6 alkyl group by the fluorine atom can be mentioned. In addition, examples of the alkoxy group having 1 to 6 carbon atoms include those in which the groups mentioned as the alkyl group having 1 to 6 carbon atoms are bonded to an oxygen atom, specifically, for example, a methoxy group, an ethoxy group, and the like. Can be mentioned.

Each primary amino group in formula (D-1) is preferably bonded to the 4-position with respect to —COO—. In addition, among R ^{1 to} R ¹⁰ , the rest other than the primary amino group are all hydrogen atoms, or at least one of adjacent to the primary amino group is other than a hydrogen atom, and the others are hydrogen atoms. Is preferred. In the former case, the planarity of the polyamic acid or its imidized polymer can be increased, and thereby the liquid crystal alignment can be improved. In the latter case, the planarity of the polyamic acid or the like is lowered by the group adjacent to the amino group, whereby the solubility of the polymer in the organic solvent can be improved. From the viewpoint of keeping the flatness moderately, the group adjacent to the amino group is preferably one having 1 to 3 carbon atoms, and particularly preferably a methyl group or an ethyl group.

Specific examples of the compound represented by the formula (D-1) include 4-aminophenyl-4′-aminobenzoate, 3,3′-dimethyl-4-aminophenyl-4′-aminobenzoate,
3,3 ′, 5,5′-tetramethyl-4-aminophenyl-4′-aminobenzoate and 3-methyl-4-aminophenyl-4′-aminobenzoate are preferred, and among these, 4-aminophenyl is particularly preferred. -4'-aminobenzoate is preferred.

  As the diamine for synthesizing the polyamic acid in the present invention, only the compound represented by the above formula (D-1) may be used, or other compounds together with the compound represented by the above formula (D-1). A diamine may 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;

  As aromatic diamines, for example, o-phenylenediamine, m-phenylenediamine, 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-phenylenediisopropyl Ridene) 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-dia Nobenzene, tetradecanoxy-2,4-diaminobenzene, pentadecanoxy-2,4-diaminobenzene, hexadecanoxy-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, cholestanyl 3,5-diaminobenzoate, cholestenyl 3,5-diaminobenzoate, 3 , 5-Diaminobenzoic acid lanostannyl, 3,6-bis (4-aminobenzoyloxy) cholestane, 3,6-bis (4-aminophenoxy) cholestane, 4- (4′-trifluoromethoxybenzoyloxy) cyclohexyl- 3,5-diaminobenzoate, 4- (4′-trifluoromethylbenzoyloxy) cyclohexyl-3,5-diaminobenzoate, 1,1-bis (4-((aminophenyl) methyl) phenyl) -4-butyl Cyclohexane, 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-heptylcyclohexane Syl) cyclohexane, 2,4-diamino-N, N-diallylaniline, 4-aminobenzylamine, 3-aminobenzylamine, 1- (2,4-diaminophenyl) piperazine-4-carboxylic acid, 4- (morpholine- 4-yl) benzene-1,3-diamine, 1,3-bis (N- (4-aminophenyl) piperidinyl) propane, α-amino-ω-aminophenylalkylene, and the following formula (A-1)

（式中、Ｘ^I及びＸ^IIは、それぞれ、単結合、＊−Ｏ−、＊−ＣＯＯ−又は＊−ＯＣＯ−（但し、「＊」を付した結合手がベンゼン環に結合する。）であり、Ｒ^Ｉは、単結合、メチレン基又は炭素数２若しくは３のアルキレン基であり、ａは０又は１であり、ｂは０〜２の整数であり、ｃは１〜２０の整数であり、ｎは０又は１である。ただし、ａ及びｂが同時に０になることはない。）
で表される化合物などを；

(In the formula, X ^I and X ^II are each a single bond, * —O—, * —COO— or * —OCO— (where a bond marked with “*” is bonded to the benzene ring). R ^I is a single bond, a methylene group or an alkylene group having 2 or 3 carbon atoms, a is 0 or 1, b is an integer of 0 to 2, and c is an integer of 1 to 20. , N is 0 or 1. However, a and b are not 0 at the same time.)
A compound represented by:

  Examples of the diaminoorganosiloxane include 1,3-bis (3-aminopropyl) -tetramethyldisiloxane, and other diamines described in JP2010-97188A. Can be used.

The formula ^-X I ^-R I ^{-X II} in (A-1) - Examples of the divalent group represented by a methylene group, an alkylene group having 2 or 3 carbon atoms, * - O -, * - COO- or _{* -O-CH 2 CH 2 -O-} ( where bond marked with "*" is bonded to the diamino phenyl group.) is preferably. 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, and 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-eicosyl group and the like. The two amino groups in the diaminophenyl group are preferably in the 2,4-position or 3,5-position with respect to other groups.

  Specific examples of the compound represented by the formula (A-1) include compounds represented by the following formulas (A-1-1) to (A-1-3).

  The ratio of the compound represented by the formula (D-1) is preferably 10 to 100 mol% with respect to the total amount of diamine. By setting the above range, even when an aliphatic or alicyclic tetracarboxylic dianhydride is used, a liquid crystal alignment film capable of exhibiting excellent liquid crystal alignment properties while improving the voltage holding ratio of the liquid crystal Can be formed.

<Molecular weight regulator>
When synthesizing the polyamic acid, 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 further improved without impairing the effects of the present invention.

Examples of molecular weight regulators 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>
The ratio of the tetracarboxylic dianhydride and the diamine used in the polyamic acid synthesis reaction is 0.2 to 2 for the tetracarboxylic dianhydride acid anhydride group to 1 equivalent of the amino group of the diamine. The ratio which becomes an equivalent is preferable, and the ratio which becomes 0.3-1.2 equivalent is still more preferable.

  The polyamic acid synthesis reaction is preferably carried out in an organic solvent. The reaction temperature at this time is preferably −20 ° C. to 150 ° C., more preferably 0 to 100 ° C. The reaction time is preferably 0.1 to 24 hours, more preferably 0.5 to 12 hours.

  Here, examples of the organic solvent include an aprotic polar solvent, phenol and derivatives thereof, alcohol, ketone, ester, ether, halogenated hydrocarbon, and hydrocarbon.

Specific examples of these organic solvents include the above aprotic polar solvents such as N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, dimethyl sulfoxide, γ-butyrolactone, tetramethylurea. Hexamethylphosphotriamide, etc .;
Examples of the phenol derivative include m-cresol, xylenol, halogenated phenol and the like;
Examples of the alcohol include methyl alcohol, ethyl alcohol, isopropyl alcohol, cyclohexanol, ethylene glycol, propylene glycol, 1,4-butanediol, triethylene glycol, and ethylene glycol monomethyl ether;
Examples of the ketone include acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone;

Examples of the ester include ethyl lactate, butyl lactate, methyl acetate, ethyl acetate, butyl acetate, methyl methoxypropionate, ethyl ethoxypropionate, diethyl oxalate, and diethyl malonate;
Examples of the ether include diethyl ether, ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol-n-propyl ether, ethylene glycol-i-propyl ether, ethylene glycol-n-butyl ether, ethylene glycol dimethyl ether, ethylene glycol ethyl ether acetate. Diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, tetrahydrofuran and the like;
Examples of the halogenated hydrocarbon include dichloromethane, 1,2-dichloroethane, 1,4-dichlorobutane, trichloroethane, chlorobenzene, o-dichlorobenzene and the like;
Examples of the hydrocarbon include hexane, heptane, octane, benzene, toluene, xylene, isoamylpropionate, isoamylisobutyrate, and diisopentyl ether.

  Among these organic solvents, an aprotic polar solvent and one or more selected from the group consisting of phenol and derivatives thereof (first group organic solvent), or one selected from the first group of organic solvents It is preferable to use a mixture of the above and one or more selected from the group consisting of alcohols, ketones, esters, ethers, halogenated hydrocarbons and hydrocarbons (second group organic solvent). In the latter case, the use ratio of the second group of organic solvents is preferably 50% by weight or less, more preferably 40% by weight or less, based on the total of the first group of organic solvents and the second group of organic solvents. More preferably, it is 30% by weight or less.

  The amount of organic solvent used (a) 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 for the preparation of the liquid crystal aligning agent as it is, or may be used for the preparation of the liquid crystal aligning agent after isolating the polyamic acid contained in the reaction solution. Or you may use for preparation of a liquid crystal aligning agent, after refine | purifying the isolated polyamic acid. Isolation and purification of the polyamic acid can be performed according to known methods.

<Imidized polymer>
The imidized polymer (polyimide) in the present invention can be obtained by dehydrating and ring-closing the synthesized polyamic acid to imidize it. In this case, the reaction solution obtained by dissolving the polyamic acid may be used for the dehydration ring-closing reaction as it is, or the polyamic acid contained in the reaction solution may be isolated and then used for the dehydration ring-closing reaction. Alternatively, the isolated polyamic acid may be purified and then subjected to a dehydration ring closure reaction.

  The polyimide in the present invention may be a completely imidized product obtained by dehydrating and cyclizing all of the amic acid structure that the polyamic acid that is a precursor thereof has, or by dehydrating and cyclizing only a part of the amic acid structure, A partially imidized product in which a structure and an imide ring structure coexist may be used. The polyimide in the present invention preferably has an imidation rate of 30% or more, more preferably 50 to 99%, and more preferably 65 to 99%. This imidation ratio represents the ratio of the number of imide ring structures to the total of the number of polyimide amic acid structures and the number of imide ring structures in percentage. Here, a part of the imide ring may be an isoimide ring.

  The polyamic acid is preferably dehydrated and closed by heating the polyamic acid, or by dissolving the polyamic acid in an organic solvent, adding a dehydrating agent and a dehydrating ring-closing catalyst to the solution, and heating the solution as necessary. . Of these, the latter method is preferred.

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

  In this way, a reaction solution containing polyimide is obtained. This reaction solution may be used as it is for the preparation of the liquid crystal aligning agent, or may be used for the preparation of the liquid crystal aligning agent after removing the dehydrating agent and the dehydrating ring-closing catalyst from the reaction solution. May be used for the preparation of a liquid crystal aligning agent, or may be used for the preparation of a liquid crystal aligning agent after purifying the isolated polyimide. These purification operations can be performed according to known methods.

<Solution viscosity of polymer>
The polyamic acid and imidized polymer (hereinafter also referred to as a specific polymer) obtained in the above manner in the present invention have a solution viscosity of 20 to 800 mPa · s when this is a 10% by weight solution. Preferably, it has a solution viscosity of 30 to 500 mPa · s.

  In addition, the solution viscosity (mPa · s) of the above polymer is based on a polymer solution having a concentration of 10% by weight prepared using a good solvent for the polymer (eg, γ-butyrolactone, N-methyl-2-pyrrolidone, etc.). The value measured at 25 ° C. using an E-type rotational viscometer.

<Other additives>
Although the liquid crystal aligning agent of this invention contains a specific polymer, it may contain the other component as needed. Examples of such other components include other polymers other than the above specific polymer, compounds having at least one epoxy group in the molecule (hereinafter referred to as “epoxy compound”), functional silane compounds, and the like. be able to.

[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, for example, a polyamic acid obtained by reacting a diamine not containing the compound represented by the formula (D-1) with tetracarboxylic dianhydride, and Polyamic acid obtained by reacting aromatic tetracarboxylic dianhydride and diamine (hereinafter referred to as “other polyamic acid”), polyimide obtained by dehydrating and ring-closing the other polyamic acid (hereinafter referred to as “other polyamic acid”) 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 or other polyimides are preferred, and other polyamic acids are more preferred. In addition, the compound used in order to synthesize | combine the said specific polymer can be mentioned as tetracarboxylic dianhydride and diamine used in order to synthesize | combine another polyamic acid and another polyimide.

  When other polymers are added to the liquid crystal aligning agent, the blending ratio is preferably 50% by weight or less, more preferably 0.1 to 40% by weight, more preferably 0.1% by weight to the total amount of the polymer in the liquid crystal aligning agent. 1 to 30% by weight is more preferable.

[Epoxy compound]
The epoxy compound can be used for improving the mechanical strength of the liquid crystal alignment film. Thereby, peeling of the film or the like can be suppressed during the rubbing process (rubbing resistance can be improved), and consequently display defects in the liquid crystal display element can be suppressed. Moreover, an epoxy compound can also be used for the purpose of the adhesive improvement of a liquid crystal aligning film and a base material.

  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, trimethylolpropane triglycidyl ether, 2,2-dibromoneopentyl glycol diglycidyl ether, N, N, N ′, N′-tetraglycidyl-m-xylenediamine, 1,3 -Bis (N, N-diglycidylaminomethyl) cyclohexane, N, N, N ', N'-tetraglycidyl-4,4'-diaminodiphe Rumetan, N, N-diglycidyl - benzylamine, N, N-diglycidyl - aminomethyl cyclohexane, N, N-diglycidyl - cyclohexyl amine may be mentioned as preferred.

  When these epoxy compounds are added to the liquid crystal aligning agent, the blending ratio 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 of the polymers contained in the liquid crystal aligning agent. preferable.

[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-trimethoxysilyl-3,6-diazanonyl acetate, 9- Triethoxysilyl-3,6-diazanonyl acetate, methyl 9-trimethoxysilyl-3,6-diazananoate, methyl 9-triethoxysilyl-3,6-diazananoate, N-benzyl-3-aminopropyltri Methoxysilane, N-benzyl-3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltriethoxysilane, glycidoxymethyltrimethoxysilane, glycidoxy Methyltriethoxysilane, 2-glycidoxyethyltrimeth Shishiran, 2-glycidoxyethyl triethoxysilane, 3-glycidoxypropyltrimethoxysilane, and 3-glycidoxypropyl triethoxy silane and the like.

  When these functional silane compounds are added to the liquid crystal aligning agent, the blending ratio 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 polymer.

[Organic solvent]
The liquid crystal aligning agent of the present invention is constituted by dissolving a specific polymer and other additives optionally blended as necessary, preferably dissolved in an organic solvent.

  Examples of the organic solvent used in the liquid crystal aligning agent of the present invention include N-methyl-2-pyrrolidone, 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, ethylene carbonate, propylene carbonate, etc. Can be mentioned. These can be used alone or in combination of two or more.

  The solid content concentration in the liquid crystal aligning agent (the ratio of the total weight of components other than the solvent of the liquid crystal aligning agent to the total weight of the liquid crystal aligning agent) is appropriately selected in consideration of viscosity, volatility, etc. It is in the range of 1 to 10% by weight. That is, the liquid crystal aligning agent of the present invention is applied to the substrate surface as described later, and preferably, when heated, a liquid crystal alignment film or a liquid crystal alignment film is formed. When the solid content concentration is less than 1% by weight, it is difficult to obtain a good liquid crystal alignment film because the film thickness is too small. On the other hand, when the solid content concentration exceeds 10% by weight, it is difficult to obtain a good liquid crystal alignment film due to excessive film thickness, and the viscosity of the liquid crystal aligning agent may increase, resulting in poor coating characteristics. There is.

  The particularly preferable range of the solid content concentration varies depending on the method used when the liquid crystal aligning agent is applied to the substrate. For example, when the spinner method is used, the solid content concentration is particularly preferably in the range of 1.5 to 4.5% by weight. In the case of the printing method, it is particularly preferable that the solid content concentration is in the range of 3 to 9% by weight, and thereby the solution viscosity is in the range of 12 to 50 mPa · s. In the case of the inkjet method, it is particularly preferable that the solid content concentration is in the range of 1 to 5% by weight, and thereby the solution viscosity is in the range of 3 to 15 mPa · s.

  The temperature at the time of preparing the liquid crystal aligning agent of this invention becomes like this. Preferably it is 10-50 degreeC, More preferably, it is 20-30 degreeC.

<Liquid crystal alignment film and liquid crystal display element>
The liquid crystal alignment film of the present invention is formed by the above liquid crystal aligning agent. Moreover, the liquid crystal display element of this invention comprises this liquid crystal aligning film. The liquid crystal display element of the present invention may be applied to a horizontal alignment type operation mode such as IPS type, TN type, STN type, or FFS type, or to a vertical alignment type operation mode such as VA type. Although it is good, it is preferably a horizontal alignment type, and it is particularly preferable to apply to the IPS type.

  Below, while explaining the manufacturing method of the liquid crystal display element of this invention, the manufacturing method of the liquid crystal aligning film of this invention is also demonstrated in the description. The liquid crystal display element of the present invention can be produced, for example, by the following steps (1) to (3). In step (1), the substrate to be used varies depending on the desired operation mode. Steps (2) and (3) are common to each operation mode.

[Step (1): Formation of coating film]
First, the liquid crystal aligning agent of this invention is apply | coated on a board | substrate, Then, a coating film is formed on a board | substrate by heating an application surface.

(1-1) When manufacturing a TN type, STN type, or VA type liquid crystal display element, a pair of two substrates provided with a patterned transparent conductive film is used as a pair on each transparent conductive film formation surface. The liquid crystal aligning agent of the present invention is preferably applied by an offset printing method, a spin coating method, a roll coater method, or an ink jet printing method, and then each coated surface is heated (preferably pre-heated (pre-baked) and fired (post-baked). ) To form a coating film. Here, as the substrate, for example, a glass such as float glass or soda glass; a transparent substrate made of a plastic such as polyethylene terephthalate, polybutylene terephthalate, polyethersulfone, polycarbonate, or poly (alicyclic olefin) can be used. As a transparent conductive film provided on one surface of the substrate, an NESA film (registered trademark of PPG, USA) made of tin oxide (SnO ₂ ), an ITO film made of indium oxide-tin oxide (In ₂ O ₃ —SnO ₂ ), etc. In order to obtain a patterned transparent conductive film which can be used, for example, a method of forming a pattern by photo-etching after forming a transparent conductive film without a pattern, a mask having a desired pattern when forming the transparent conductive film The method using can be used. When applying the liquid crystal aligning agent, in order to further improve the adhesion between the substrate surface and the transparent conductive film and the coating film, a functional silane compound or functional titanium is formed on the surface of the substrate surface on which the coating film is to be formed. You may give the pretreatment which apply | coats a compound etc. previously.

  The coated surface after application of the liquid crystal aligning agent is then pre-heated (pre-baked) and further baked (post-baked) 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 formed coating film is preferably 0.001-1 μm, more preferably 0.005-0.5 μm.

  (1-2) On the other hand, when manufacturing an IPS type liquid crystal display element, the conductive film forming surface of the substrate provided with the comb-shaped transparent conductive film and the counter substrate provided with no conductive film The liquid crystal aligning agent of this invention is apply | coated to one surface, respectively, Then, a coating film is formed by heating each application surface. Regarding the material used for the substrate and the transparent conductive film, the coating method, the heating conditions after coating, the patterning method for the transparent conductive film, the pretreatment of the substrate, and the preferred film thickness of the coating film to be formed is as described in (1-1 ).

  In both cases (1-1) and (1-2), after applying a liquid crystal aligning agent on the substrate, a coating film to be an alignment film is formed by removing the organic solvent. At this time, when the polymer contained in the liquid crystal aligning agent of the present invention is a polyamic acid or an imidized polymer having an imide ring structure and an amic acid structure, heating is further performed after the coating film is formed. By doing so, the dehydration ring-closing reaction may be advanced to form a more imidized coating film.

[Step (2): rubbing treatment]
When manufacturing a TN type, STN type, or IPS type liquid crystal display element, the coating film formed in the step (1) is fixed in a certain direction with a roll wound with a cloth made of fibers such as nylon, rayon, and cotton. Apply rubbing rubbing treatment. Thereby, the orientation ability of liquid crystal molecules is imparted to the coating film to form a liquid crystal orientation film.

  Furthermore, with respect to the liquid crystal alignment film, a treatment for changing the pretilt angle of a part of the liquid crystal alignment film by irradiating a part of the liquid crystal alignment film with ultraviolet rays, or a resist film on a part of the surface of the liquid crystal alignment film In addition, after performing the rubbing process in a direction different from the previous rubbing process, a process of removing the resist film may be performed so that the liquid crystal alignment film has different liquid crystal alignment ability for each region. In this case, it is possible to improve the visibility characteristics of the obtained liquid crystal display element.

  In addition, when manufacturing a VA type liquid crystal display element, although the coating film formed at the said process (1) can be used as a liquid crystal aligning film as it is, you may perform a rubbing process with respect to this coating film.

[Step (3): Construction of liquid crystal cell]
The pair of substrates on which the liquid crystal alignment films are formed as described above are arranged to face each other through a gap (cell gap) so that the rubbing directions of the liquid crystal alignment films of the two substrates are orthogonal or antiparallel. A peripheral portion of a single substrate is bonded using a sealant, and liquid crystal is injected and filled into the cell gap defined by the substrate surface and the sealant, and the injection hole is sealed to form a liquid crystal cell. And a liquid crystal display element can be obtained by bonding a polarizing plate on the outer surface of a liquid crystal cell so that the polarization direction thereof matches or is orthogonal to the rubbing direction of the liquid crystal alignment film formed on each substrate.

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

  Examples of the liquid crystal include nematic liquid crystal and smectic liquid crystal. Among them, nematic liquid crystal is preferable. For example, Schiff base liquid crystal, azoxy liquid crystal, biphenyl liquid crystal, phenylcyclohexane liquid crystal, ester liquid crystal, terphenyl liquid crystal, biphenyl. Cyclohexane liquid crystals, pyrimidine liquid crystals, dioxane liquid crystals, bicyclooctane liquid crystals, cubane liquid crystals, and the like can be used. Further, cholesteric liquid crystals such as cholestyl chloride, cholesteryl nonate, and cholesteryl carbonate; chiral agents such as those sold under the trade names “C-15” and “CB-15” (manufactured by Merck & Co., Inc.). A ferroelectric liquid crystal such as p-decyloxybenzylidene-p-amino-2-methylbutylcinnamate may be added and used.

  As a polarizing plate to be bonded to the outer surface of the liquid crystal cell, a polarizing film or an H film itself in which a polarizing film called an “H film” in which iodine is absorbed while stretching and aligning polyvinyl alcohol is sandwiched between cellulose acetate protective films The polarizing plate which consists of can be mentioned.

  The liquid crystal display element of the present invention can be effectively applied to various devices such as watches, portable games, word processors, notebook computers, car navigation systems, camcorders, PDAs, digital cameras, mobile phones, various monitors. It can be used for a display device such as a liquid crystal television.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

The solution viscosity of the polymer in each of the following synthesis examples is a value measured at 25 ° C. using an E-type rotational viscometer. Moreover, the imidation ratio of polyimide was measured as follows.
[Imidation rate of polyimide]
The polyimide solution was poured into pure water, and the resulting precipitate was sufficiently dried under reduced pressure at room temperature, then dissolved in deuterated dimethyl sulfoxide, and ¹ H-NMR was measured at room temperature using tetramethylsilane as a reference substance. From the obtained ¹ H-NMR spectrum, the imidization ratio was determined by the formula shown by the following formula (1).
Imidation ratio (%) = (1-A ¹ / A ² × α) × 100 (1)
(In Formula (1), A ¹ is a peak area derived from protons of NH groups appearing near a chemical shift of 10 ppm, A ² is a peak area derived from other protons, and α is a precursor of a polymer (polyamic acid). The number ratio of other protons to one proton of NH group in)

<Synthesis of polymer>
[Synthesis Examples 1 to 7 and Comparative Synthesis Examples 1 to 11]
To N-methyl-2-pyrrolidone, the amounts of diamine and tetracarboxylic dianhydride shown in Table 1 below were added in this order to obtain a solution having a monomer concentration of 15% by weight. Thereafter, the reaction was performed at room temperature for 6 hours to obtain solutions containing polyamic acids (PA-1) to (PA-9) and (PAR-1) to (PAR-11), respectively. A small amount of each solution was taken and N-methyl-2-pyrrolidone was added to obtain a solution having a polyamic acid concentration of 10% by weight. The results of measuring the solution viscosity are shown in Table 1 below. In addition, each half amount of these polyamic acid solutions was ensured, and it used in subsequent Examples 1-9 and Comparative Examples 1-11, respectively.

  Among the polyamic acid solutions, for (PA-2) to (PA-4) and (PAR-5) to (PAR-7), N-methyl-2-pyrrolidone is added to the remaining half, and the polyamic acid concentration The solution was 6% by weight. Here, pyridine and acetic anhydride were added to each mole of the amic acid unit possessed by the polyamic acid so as to have the molar ratio shown in Table 1 below, and then heated to 110 ° C. for 4 hours for dehydration ring closure reaction. Went. After the dehydration ring-closing reaction, the solvent in the system was replaced with new N-methyl-2-pyrrolidone (removing pyridine and acetic anhydride used in the dehydration ring-closing reaction outside of the system in this operation) to obtain polyimide (PI -1) to (PI-3) and (PIR-1) to (PIR-3) containing 15% by weight, respectively. While measuring the imidation ratio of each polyimide contained in these polyimide solutions, a small fraction of each solution was added, and the solution viscosity when N-methyl-2-pyrrolidone was added to make a solution having a polyimide concentration of 10% by weight was measured. did. The respective measurement results are shown in Table 1 below. These polyimide solutions were used in the following Examples 10 to 12 and Comparative Examples 12 to 14, respectively.

In Table 1, the abbreviations of diamine and tetracarboxylic acid anhydride have the following meanings, respectively.
<Diamine>
d-1: 4-aminophenyl-4′-aminobenzoate d-2: 4,4′-diaminodiphenyl ether d-3: 4,4′-diaminodiphenylmethane d-4: 2,2-bis [4- (4 -Aminophenoxy) phenyl] propane d-5: p-phenylenediamine <tetracarboxylic dianhydride>
t-1: 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CB)
t-2: 2,3,5-tricarboxycyclopentyl acetic acid dianhydride t-3: 1,3,3a, 4,5,9b-hexahydro-8-methyl-5- (tetrahydro-2,5-dioxo- 3-furanyl) -naphtho [1,2-c] furan-1,3-dione t-4: 1,3,3a, 4,5,9b-hexahydro-5- (tetrahydro-2,5-dioxo-3 -Furanyl) naphtho [1,2-c] furan-1,3-dione t-5: (1S, 2S, 4R, 5R) -cyclohexanetetracarboxylic dianhydride t-6: (1R, 2S, 4S, 5R) -cyclohexanetetracarboxylic dianhydride t-7: 1,2,3,4-butanetetracarboxylic dianhydride t-8: pyromellitic dianhydride (PMDA)

Example 1
<Preparation of liquid crystal aligning agent>
Γ-butyrolactone (BL), N-methyl-2-pyrrolidone (NMP) and butyl cellosolve (BC) are added to the solution containing the polyamic acid (PA-1) obtained in Synthesis Example 1, and a crosslinking agent (adhesive) As an improvement agent), N, N, N ′, N′-tetraglycidyl-4,4′-diaminodiphenylmethane, which is an epoxy compound, is added in an amount of 10 parts by weight, and the solvent ratio is BL: NMP: BC = 40: 40: 20 (weight ratio) and a solid content concentration of 4.0% by weight were obtained. After sufficiently stirring this solution, a liquid crystal aligning agent was prepared by filtering using a filter having a pore size of 1 μm. The alignment agent at this time is “with a crosslinking agent”, and in the preparation of the liquid crystal alignment agent described above, N, N, N ′, N′-tetraglycidyl-4,4′-diaminodiphenylmethane is not added. "

<Manufacture and evaluation of liquid crystal cells>
A liquid crystal cell was produced using this liquid crystal aligning agent and evaluated as follows.
[Manufacture of liquid crystal cells]
After applying the liquid crystal aligning agent prepared above on a glass substrate having a thickness of 1 mm having a comb electrode on one side with a spinner and prebaking on a hot plate at 80 ° C. for 1 minute. The film was post-baked on a hot plate at 230 ° C. for 10 minutes to form a coating film having a thickness of about 800 mm. Using a rubbing machine having a roll around which a nylon cloth is wound on the formed coating surface, the roll rotation speed is 1,000 rpm, the stage moving speed is 25 mm / second, and the length of pushing the hair foot is 0.4 mm. A rubbing treatment was performed to give liquid crystal alignment ability. Further, this substrate was ultrasonically cleaned in ultrapure water for 1 minute and dried in a 100 ° C. clean oven for 10 minutes to produce a substrate having a liquid crystal alignment film on the surface having comb-like chrome electrodes. The substrate having this liquid crystal alignment film was referred to as “substrate A”.

  Separately, a liquid crystal aligning agent coating film is formed on one surface of a 1 mm thick glass substrate having no electrodes in the same manner as described above, rubbed, washed and dried, and a liquid crystal on one side. A substrate having an alignment film was manufactured. The substrate having this liquid crystal alignment film was referred to as “substrate B”.

  Subsequently, an epoxy resin adhesive containing aluminum oxide spheres having a diameter of 5.5 μm is applied to the outer edge of the surface having the liquid crystal alignment film subjected to the rubbing treatment so that the rubbing direction in each liquid crystal alignment film becomes antiparallel. The two substrates A and B were placed opposite to each other with a gap between them, and the outer edge portions were brought into contact with each other and pressed to cure the adhesive. Next, a nematic liquid crystal (MLC-2042, manufactured by Merck & Co., Inc.) is filled between the pair of substrates from the liquid crystal injection port, and then the liquid crystal injection port is sealed with an acrylic photo-curing adhesive, whereby an IPS type liquid crystal cell is obtained. Manufactured.

[Evaluation of liquid crystal display elements]
-Evaluation of liquid crystal orientation About the liquid crystal cell manufactured above, it observed using the polarizing microscope. Evaluation of liquid crystal alignment was `` excellent '' when almost no light leakage was observed, `` good '' when very little light leakage was observed, and `` good '' when fluid leakage was clearly recognized. Went as "bad". Moreover, about what evaluated liquid crystal orientation "excellent", three-step evaluation was performed and it evaluated as 1, 2, 3 in order with favorable liquid crystal orientation. The results are shown in Table 2 below.

・ Evaluation of voltage holding characteristics Among the liquid crystal cells manufactured as described above, a voltage of 1V was applied for 30 seconds at 60 ° C., and the voltage holding ratio after release of the voltage was 1 V and the frame period at 60 ° C. Measurement was performed at 167 msec. The measurement results are shown in Table 2 below. Table 2 shows the results of the three-stage evaluation of the voltage holding characteristics together with the value of the voltage holding ratio. A voltage holding ratio of 99% or more is ◎, 98% or more and less than 99% is ◯, Those with less than 98% were shown as x.

(Examples 2-12 and Comparative Examples 1-14)
In Example 1 above, a liquid crystal aligning agent was prepared in the same manner as in Example 1 except that a solution containing the polymer shown in Table 1 was used as the polymer solution. The orientation and voltage holding characteristics were evaluated. The evaluation results are shown in Table 2 below.

  Regarding the liquid crystal orientation, in the case of no crosslinking agent, light leakage was hardly observed in any of Examples 1 to 12. Among these, in Examples 1, 3, 4, 8, and 10 to 12, it was found that almost no light leakage was observed even in the presence of the crosslinking agent, and that the flow orientation due to the addition of the crosslinking agent hardly occurred. . In addition, the voltage holding ratio in the case of the presence of the crosslinking agent showed a particularly high value in Examples 1, 2, 5, 6, and 10.

  Among them, in Examples 1 and 10 in which CB was used alone as the tetracarboxylic dianhydride, the voltage holding ratio was as high as 99.4% or more, and particularly excellent in that both the liquid crystal orientation and the voltage holding characteristics can be achieved. It was. Moreover, in Example 8 which is a mixed system of CB and PMDA, the liquid crystal orientation is the best among Examples 1 to 12, and the voltage holding ratio is also lower than those of Examples 1 and 10, but sufficiently. it was high.

  On the other hand, in Comparative Examples 1 to 10 and 12 to 14, the voltage holding ratio was equivalent to that of Examples 1 to 12, but inferior to that of Examples 1 to 12 in liquid crystal alignment. In particular, in Comparative Examples 1 to 10 including polyamic acids PAR-1 to PAR-10, fluid orientation and light leakage were clearly observed when a crosslinking agent was added. From this, it can be said that in PAR-1 to PAR-10, the addition of a crosslinking agent tends to cause a decrease in liquid crystal alignment.

  Moreover, although the thing using the aromatic ring tetracarboxylic dianhydride (comparative example 11) was excellent about liquid crystal aligning property, the voltage holding rate was as low as less than 98%.

Claims (8)

A liquid crystal aligning agent containing at least one of a polyamic acid obtained by reacting a tetracarboxylic dianhydride and a diamine and an imidized polymer thereof,
The tetracarboxylic dianhydride includes at least one of an aliphatic tetracarboxylic dianhydride and an alicyclic tetracarboxylic dianhydride,
The liquid crystal aligning agent characterized by the said diamine containing the compound represented by a following formula (D-1).

(Wherein R ^{1 to} R ¹⁰ are one of R ^{1 to} R ⁵ and one of R ^{6 to} R ¹⁰ are primary amino groups, and the rest are each independently a hydrogen atom or a fluorine atom. Or an alkyl group having 1 to 6 carbon atoms, an alkoxy group, or a fluoroalkyl group.) The aliphatic tetracarboxylic dianhydride is 1,2,3,4-butanetetracarboxylic dianhydride;
The alicyclic tetracarboxylic dianhydride is 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentylacetic acid dianhydride, 1,3,3a, 4, 5,9b-Hexahydro-8-methyl-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] furan-1,3-dione, 1,3,3a, 4 5,9b-Hexahydro-5- (tetrahydro-2,5-dioxo-3-furanyl) naphtho [1,2-c] furan-1,3-dione, bicyclo [3,3,0] octane-2,4 The liquid crystal aligning agent according to claim 1, which is at least one selected from the group consisting of 1,6,8-tetracarboxylic dianhydride and cyclohexanetetracarboxylic dianhydride.   The tetracarboxylic dianhydride is a mixture of at least one of the aliphatic tetracarboxylic dianhydride and the alicyclic tetracarboxylic dianhydride and an aromatic tetracarboxylic dianhydride. 2. A liquid crystal aligning agent according to 2.   The alicyclic tetracarboxylic dianhydride is 1,2,3,4-cyclobutanetetracarboxylic dianhydride, (1S, 2S, 4R, 5R) -cyclohexanetetracarboxylic dianhydride, (1R, 2S , 4S, 5R) -cyclohexanetetracarboxylic dianhydride and at least one selected from the group consisting of 2,3,5-tricarboxycyclopentylacetic acid dianhydride. The liquid crystal aligning agent of description.   The liquid crystal aligning film formed with the liquid crystal aligning agent as described in any one of Claims 1 thru | or 4.   A liquid crystal display device comprising the liquid crystal alignment film according to claim 5. A polyamic acid obtained by reacting at least one of an aliphatic tetracarboxylic dianhydride and an alicyclic tetracarboxylic dianhydride with a diamine represented by the following formula (D-1).

(Wherein R ^{1 to} R ¹⁰ are one of R ^{1 to} R ⁵ and one of R ^{6 to} R ¹⁰ are primary amino groups, and the rest are each independently a hydrogen atom or a fluorine atom. Or an alkyl group having 1 to 6 carbon atoms, an alkoxy group, or a fluoroalkyl group.)   A polyimide obtained by imidizing the polyamic acid according to claim 7.