JP4788899B2 - Liquid crystal aligning agent and liquid crystal display element - Google Patents

Description

  The present invention relates to a vertical alignment type liquid crystal alignment agent. More specifically, the present invention relates to a vertical alignment type liquid crystal aligning agent particularly suitable for an MVA (Multi-domain Vertical Alignment) type liquid crystal display element excellent in vertical alignment and printability.

Currently, as a liquid crystal display element, a liquid crystal alignment film made of polyamic acid, polyimide, or the like is formed on the surface of a substrate on which a transparent conductive film is provided to form a liquid crystal display element substrate. A nematic liquid crystal layer having positive dielectric anisotropy is formed in a cell having a sandwich structure so that the major axis of the liquid crystal molecules is continuously twisted 90 degrees from one substrate to the other. A TN liquid crystal display element having a so-called TN (twisted nematic) liquid crystal cell is known. Further, STN (Super Twisted Nematic) type liquid crystal display elements and vertical alignment type liquid crystal display elements, which have a higher contrast than the TN type liquid crystal display elements and have less viewing angle dependency, have been developed. This STN type liquid crystal display element uses nematic liquid crystal blended with a chiral agent which is an optically active substance as liquid crystal, and the major axis of liquid crystal molecules is continuously twisted over 180 degrees between substrates. The birefringence effect generated by the above is utilized.
In contrast, “Liquid Crystal” Vol. 3 No. As described in 2 117 (1999) and Japanese Patent Application Laid-Open No. 11-258605, a vertical alignment type liquid crystal display element called an MVA method is proposed in which protrusions are formed on ITO to control the alignment direction of the liquid crystal. ing. The MVA liquid crystal display element is excellent in terms of manufacturing process, such as excellent viewing angle and contrast, and need not be rubbed in forming the liquid crystal alignment film. A liquid crystal alignment film suitable for the MVA system is required to have excellent performance such as excellent vertical alignment and a short afterimage erasing time of the liquid crystal display element.

  An object of the present invention is to provide a vertical alignment type liquid crystal aligning agent excellent in vertical alignment and printability and a liquid crystal display element using the same.

  Still other objects and advantages of the present invention will become apparent from the following description.

According to the present invention, the above object and advantage of the present invention are at least one selected from the group consisting of a repeating unit represented by the following formula (I-1) and a repeating unit represented by the following formula (I-2). polymer having repeating units and have a repeating unit having an imide ring (hereinafter, also referred to as "specific polymer") is configured is contained dissolved in an organic solvent, provided that the organic solvent is 3-butoxy - Achieved by a vertical alignment type liquid crystal aligning agent comprising N, N-dimethylpropanamide, 3-methoxy-N, N-dimethylpropanamide or 3-hexyloxy-N, N-dimethylpropanamide Is done. The polymer preferably has 40 mol% or more of repeating units having an imide ring in all repeating units.

(In the formula, P ¹ is a tetravalent organic group, and Q ¹ is a group represented by the following formula (Q-1) or (Q-2).)

(In the formula, P ² is a tetravalent organic group, and Q ² is a group represented by the following formula (Q-1) or (Q-2).)

(In the formula, X consists of —O—, —CO—, —COO—, —OCO—, —NHCO—, —CONH—, —S—, a methylene group, an alkylene group having 2 to 6 carbon atoms, and a phenylene group. R ¹ is a divalent group selected from the group, and R ¹ represents an alkyl group having 10 to 20 carbon atoms, a monovalent organic group having an alicyclic skeleton having 4 to 40 carbon atoms, or a fluorine atom having 6 or more carbon atoms. A monovalent organic group.)

(In the formula, X consists of —O—, —CO—, —COO—, —OCO—, —NHCO—, —CONH—, —S—, a methylene group, an alkylene group having 2 to 6 carbon atoms, and a phenylene group. (It is a divalent group selected from the group, and R ² is a divalent organic group having an alicyclic skeleton having 4 to 40 carbon atoms.)

  According to the liquid crystal aligning agent of the present invention, a coating film with high film thickness uniformity can be formed even when the environmental temperature during printing changes, and a liquid crystal aligning film having good liquid crystal alignment is formed. be able to. For this reason, the liquid crystal display element without an orientation defect can be obtained. Furthermore, a liquid crystal display element having a liquid crystal alignment film formed using the liquid crystal aligning agent of the present invention can be effectively used in various devices, for example, a direct-view personal computer monitor, a liquid crystal television, and a projection system. Used in transmissive and reflective display devices.

  Hereinafter, the present invention will be described in detail.

  The vertical alignment type liquid crystal aligning agent of the present invention is constituted by dissolving a specific polymer in an organic solvent. The specific polymer can be obtained by dehydrating and ring-closing part or all of the polyamic acid.

[Polyamic acid]
<Tetracarboxylic dianhydride>
The tetracarboxylic dianhydride used for the synthesis of the polyamic acid is preferably an alicyclic tetracarboxylic dianhydride. Specific examples of the alicyclic tetracarboxylic dianhydride include, for example, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2-dimethyl-1,2,3,4-cyclobutanetetracarboxylic Acid dianhydride, 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-dichloro-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1 , 2,3,4-tetramethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 1,2,4,5 -Cyclohexanetetracarboxylic dianhydride, 3,3 ', 4,4'-dicyclohexyltetracarboxylic dianhydride, cis-3,7-dibutylcycloocta-1,5-diene-1,2,5,6 -Tetracarboxylic acid Anhydride, 2,3,5-tricarboxycyclopentylacetic acid dianhydride, 3,5,6-tricarbonyl-2-carboxynorbornane-2: 3,5: 6-dianhydride, 2,3,4,5 -Tetrahydrofurantetracarboxylic 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-5-methyl-5 (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] -furan-1 , 3-dione, 1,3,3a, 4,5,9b-hexahydro-5-ethyl-5 (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] -furan-1 , 3-dione, 1,3,3a, 4 5,9b-Hexahydro-7-methyl-5 (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] -furan-1,3-dione, 1,3,3a, 4 5,9b-Hexahydro-7-ethyl-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, 1,3,3a, 4 5,9b-Hexahydro-8-ethyl-5 (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] -furan-1,3-dione, 1,3,3a, 4 5,9b-Hexahydro-5,8-dimethyl-5 (tetrahydro 2,5-dioxo-3-furanyl) -naphtho [1,2-c] -furan-1,3-dione, 5- (2,5-dioxotetrahydrofural) -3-methyl-3-cyclohexene-1 , 2-dicarboxylic dianhydride, bicyclo [2.2.2] -oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, 3-oxabicyclo [3.2.1] Octane-2,4-dione-6-spiro-3 ′-(tetrahydrofuran-2 ′, 5′-dione), compounds represented by the following formulas (I) and (II),

(In the formula, R ³ and R ⁶ represent a divalent organic group having an aromatic ring, R ⁴ and R ⁵ represent a hydrogen atom or an alkyl group, and a plurality of R ⁴ and R ⁵ are the same. But it may be different.)

In addition, aliphatic tetracarboxylic dianhydrides such as butanetetracarboxylic dianhydride;
Pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenylsulfone tetracarboxylic dianhydride, 1,4,5, 8-naphthalene tetracarboxylic dianhydride, 2,3,6,7-naphthalene tetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyl ether tetracarboxylic dianhydride, 3,3 ′, 4,4′-dimethyldiphenylsilanetetracarboxylic dianhydride, 3,3 ′, 4,4′-tetraphenylsilanetetracarboxylic dianhydride, 1,2,3,4-furantetracarboxylic dianhydride 4,4′-bis (3,4-dicarboxyphenoxy) diphenyl sulfide dianhydride, 4,4′-bis (3,4-dicarboxyphenoxy) diphenylsulfone dianhydride, 4,4′-bis ( 3,4-dicar Boxyphenoxy) diphenylpropane dianhydride, 3,3 ′, 4,4′-perfluoroisopropylidene diphthalic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, bis (Phthalic acid) phenylphosphine oxide dianhydride, p-phenylene-bis (triphenylphthalic acid) dianhydride, m-phenylene-bis (triphenylphthalic acid) dianhydride, bis (triphenylphthalic acid) -4 , 4′-diphenyl ether dianhydride, bis (triphenylphthalic acid) -4,4′-diphenylmethane dianhydride, ethylene glycol-bis (anhydro trimellitate), propylene glycol-bis (anhydro trimellitate) 1,4-butanediol-bis (anhydrotrimellitate), 1,6-hexanediol-bis (anhydride) Trimetrate), 1,8-octanediol-bis (anhydrotrimellitate), 2,2-bis (4-hydroxyphenyl) propane-bis (anhydrotrimellitate), the following formulas (1) to (4) An aromatic tetracarboxylic dianhydride such as a compound represented by These may be used alone or in combination of two or more.

  Among the tetracarboxylic dianhydrides, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 2,3,4-tetramethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 2,3,5-tricarboxy Cyclopentyl acetic acid dianhydride, 5- (2,5-dioxotetrahydrofural) -3-methyl-3-cyclohexene-1,2-dicarboxylic dianhydride, cis-3,7-dibutylcycloocta-1,5 -Diene-1,2,5,6-tetracarboxylic dianhydride, 3,5,6-tricarbonyl-2-carboxynorbornane-2: 3,5: 6-dianhydride, 1,3,3a, 4,5,9b- Xahydro-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, 1,3,3a, 4,5,9b-hexahydro-5 8-Dimethyl-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] furan-1,3-dione, bicyclo [2.2.2] -oct-7-ene -2,3,5,6-tetracarboxylic dianhydride, 3-oxabicyclo [3.2.1] octane-2,4-dione-6-spiro-3 '-(tetrahydrofuran-2', 5 ' -Dione), among the compounds represented by the above formula (I), 5) to alicyclic tetracarboxylic dianhydride such as a compound represented by (7) and an alicyclic compound such as a compound represented by the following formula (8) among the compounds represented by the above formula (II) Tetracarboxylic acid dianhydride is preferable from the viewpoint of exhibiting good liquid crystal orientation, and particularly preferable examples include 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-dimethyl- 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, cis-3,7-dibutylcycloocta-1,5-diene-1,2,5,6- Tetracarboxylic dianhydride, 3,5,6-tricarbonyl-2-carboxynorbornane-2: 3,5: 6-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, 3-oxabicyclo [3.2.1] octane-2,4-dione-6-spiro-3 Examples include '-(tetrahydrofuran-2', 5'-dione) and a compound represented by the following formula (5).

Among the other tetracarboxylic dianhydrides other than the alicyclic tetracarboxylic dianhydrides, for example, butanetetracarboxylic dianhydride, pyromellitic dianhydride, 3,3 ′, 4, Examples include 4′-benzophenone tetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenylsulfone tetracarboxylic dianhydride, 1,4,5,8-naphthalene tetracarboxylic dianhydride, and the like.
Among these tetracarboxylic dianhydrides, the alicyclic tetracarboxylic dianhydride is preferably 50 mol% or more based on the total tetracarboxylic dianhydrides.

<Diamine>
The group represented by the formula (Q-1) and the formula (Q-2) is a diamine-derived group that synthesizes a polyamic acid. Hereinafter, the diamine having a group represented by the formula (Q-1) or the formula (Q-2) is also referred to as a “specific diamine”.
In the above formula (Q-1), examples of the alkyl group having 10 to 20 carbon atoms represented by R ¹ include n-decyl group, n-dodecyl group, n-pentadecyl group, n-hexadecyl group, n- An octadecyl group, n-eicosyl group, etc. are mentioned.
Examples of the organic group having an alicyclic skeleton having 4 to 40 carbon atoms represented by R ¹ in the formula (Q-1) and R ² in the formula (Q-2) include cyclobutane and cyclopentane. Groups having an alicyclic skeleton derived from cycloalkane such as cyclohexane and cyclodecane; groups having a steroid skeleton such as cholesterol and cholestanol; groups having a bridged alicyclic skeleton such as norbornene and adamantane. Among these, an n-octadecyl group, a group having an alicyclic skeleton derived from cyclohexane, or a group having a steroid skeleton is particularly preferable. The organic group having an alicyclic skeleton may be a group substituted with a halogen atom, preferably a fluorine atom.

Further, examples of the group having a fluorine atom having 6 or more carbon atoms represented by R ¹ in the formula (Q-1) include 6 carbon atoms such as an n-hexyl group, an n-octyl group, and an n-decyl group. In the above linear alkyl group; an alicyclic hydrocarbon group having 6 or more carbon atoms such as a cyclohexyl group or a cyclooctyl group; an organic group such as an aromatic hydrocarbon group having 6 or more carbon atoms such as a phenyl group or a biphenyl group Examples thereof include a group in which part or all of the hydrogen atoms are substituted with a fluorine atom or a fluoroalkyl group.
The divalent organic group represented by X in the above formula (Q-1) and the above formula (Q-2) is -O-, -COO-, -OCO-, -NHCO-, -CONH-, —CO—, a methylene group, an alkylene group having 2 to 6 carbon atoms, or a phenylene group. Of these, groups represented by -O-, -COO-, and -OCO- are particularly preferred.
Specific examples of the diamine having the group represented by the above formula (Q-1) include dodecanoxy-2,4-diaminobenzene, pentadecanoxy-2,4-diaminobenzene, hexadecanoxy-2,4-diaminobenzene, octadecanoxy- Preferred examples include 2,4-diaminobenzene and compounds represented by the following formulas (9) to (16).

Specific examples of the diamine having a group represented by the above formula (Q-2) include diamines represented by the following formulas (17) to (21).

  In the synthesis of the polyamic acid used in the present invention, other diamine compounds other than the specific diamine may be used in combination so as not to impair the effects of the present invention. Examples of other diamine compounds include p-phenylenediamine, m-phenylenediamine, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylethane, 4,4′-diaminodiphenyl sulfide, and 4,4′-diamino. Diphenylsulfone, 3,3′-dimethyl-4,4′-diaminobiphenyl, 4,4′-diaminobenzanilide, 4,4′-diaminodiphenyl ether, 1,5-diaminonaphthalene, 3,3-dimethyl-4, 4′-diaminobiphenyl, 5-amino-1- (4′-aminophenyl) -1,3,3-trimethylindane, 6-amino-1- (4′-aminophenyl) -1,3,3-trimethyl Indane, 3,4'-diaminodiphenyl ether, 3,3'-diaminobenzophenone, 3,4'-diamidine Benzophenone, 4,4′-diaminobenzophenone, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane, 2, 2-bis (4-aminophenyl) hexafluoropropane, 2,2-bis [4- (4-aminophenoxy) phenyl] sulfone, 1,4-bis (4-aminophenoxy) benzene, 1,3-bis ( 4-aminophenoxy) benzene, 1,3-bis (3-aminophenoxy) benzene, 9,9-bis (4-aminophenyl) -10-hydroanthracene, 2,7-diaminofluorene, 9,9-bis ( 4-aminophenyl) fluorene, 4,4′-methylene-bis (2-chloroaniline), 2,2 ′, 5,5′-tetrachloro- , 4′-diaminobiphenyl, 2,2′-dichloro-4,4′-diamino-5,5′-dimethoxybiphenyl, 3,3′-dimethoxy-4,4′-diaminobiphenyl, 1,4,4 ′ -(P-phenyleneisopropylidene) bisaniline, 4,4 '-(m-phenyleneisopropylidene) bisaniline, 2,2'-bis [4- (4-amino-2-trifluoromethylphenoxy) phenyl] hexafluoropropane , 4,4′-diamino-2,2′-bis (trifluoromethyl) biphenyl, 4,4′-bis [(4-amino-2-trifluoromethyl) phenoxy] -octafluorobiphenyl, etc. ;

1,3-bis (aminomethyl) benzene, 1,3-propanediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, 4,4-diaminoheptamethylenediamine 1,4-diaminocyclohexane, isophorone diamine, tetrahydrodicyclopentadienylenediamine, hexahydro-4,7-methanoin danylene dimethylene diamine, tricyclo [6.2.1.0 ^2,7 ] -undecylenedimethyl diamine Aliphatic and cycloaliphatic diamines such as 4,4'-methylenebis (cyclohexylamine);
2,3-diaminopyridine, 2,6-diaminopyridine, 3,4-diaminopyridine, 2,4-diaminopyrimidine, 5,6-diamino-2,3-dicyanopyrazine, 5,6-diamino-2,4 -Dihydroxypyrimidine, 2,4-diamino-6-dimethylamino-1,3,5-triazine, 1,4-bis (3-aminopropyl) piperazine, 2,4-diamino-6-isopropoxy-1,3 , 5-triazine, 2,4-diamino-6-methoxy-1,3,5-triazine, 2,4-diamino-6-phenyl-1,3,5-triazine, 2,4-diamino-6-methyl -S-triazine, 2,4-diamino-1,3,5-triazine, 4,6-diamino-2-vinyl-s-triazine, 2,4-diamino-5-phenylthiazole, 2,6- Aminopurine, 5,6-diamino-1,3-dimethyluracil, 3,5-diamino-1,2,4-triazole, 6,9-diamino-2-ethoxyacridine lactate, 3,8-diamino-6 Two primary amino groups in the molecule, such as phenylphenanthridine, 1,4-diaminopiperazine, 3,6-diaminoacridine, bis (4-aminophenyl) phenylamine, and nitrogen atoms other than the primary amino group A diamine having:
Examples thereof include diaminoorganosiloxane represented by the following formula (III).

(Wherein R ⁷ represents a hydrocarbon group having 1 to 12 carbon atoms, and a plurality of R ⁷ may be the same or different, p is an integer of 1 to 3, and q is 1 to 20) Is an integer.)
These other diamine compounds can be used alone or in combination of two or more.

Among these, p-phenylenediamine, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenyl sulfide, 1,5-diaminonaphthalene, 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-cyclohexanediamine 4,4′-methylenebis (cyclohexylamine), 1,4-bis (4-amino) Phenoxy) benzene, 4,4-bis (4-aminophenoxy) biphenyl, 2,6-diaminopyridine, 3,4-diaminopyridine, 2,4-diaminopyrimidine, and 3,6-diamino acridine is preferred.
The proportion of the specific diamine in the total diamine component in the total polymer contained in the liquid crystal aligning agent of the present invention is preferably at least 5 mol%, more preferably at least 10 mol%, based on the total amount of the diamine component. . When this use ratio is less than 5 mol%, a sufficient effect on the vertical alignment may not be obtained.

<Synthesis of polyamic acid>
The ratio of tetracarboxylic dianhydride and diamine used for the polyamic acid synthesis reaction is 0.2 to 2 equivalents of tetracarboxylic dianhydride acid anhydride group to 1 equivalent of amino group of diamine. The ratio is preferably, more preferably 0.3 to 1.2 equivalent.
The polyamic acid synthesis reaction is preferably performed in an organic solvent under a temperature condition of −20 ° C. to 150 ° C., more preferably 0 to 100 ° C.

  Here, the organic solvent is not particularly limited as long as it can dissolve the synthesized polyamic acid. For example, 1-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, 3- Amide solvents such as butoxy-N, N-dimethylpropanamide, 3-methoxy-N, N-dimethylpropanamide, 3-hexyloxy-N, N-dimethylpropanamide, dimethyl sulfoxide, γ-butyrolactone, tetramethylurea And aprotic polar solvents such as hexamethylphosphotriamide; and phenolic solvents such as m-cresol, xylenol, phenol, and halogenated phenol. The amount of organic solvent used (α) is usually such that the total amount (β) of tetracarboxylic dianhydride and diamine compound is 0.1 to 30% by weight based on the total amount (α + β) of the reaction solution. It is preferable that the amount is small.

  In addition, the said organic solvent can use together the alcohol, ketone, ester, ether, halogenated hydrocarbon, hydrocarbon, etc. which are poor solvents of a polyamic acid in the range in which the polyamic acid to produce | generate does not precipitate. Specific examples of such poor solvents include, for example, methyl alcohol, ethyl alcohol, isopropyl alcohol, cyclohexanol, 4-hydroxy-4-methyl-2-pentanone, ethylene glycol, propylene glycol, 1,4-butanediol, triethylene glycol. , Ethylene glycol monomethyl ether, ethyl lactate, butyl lactate, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, methyl acetate, ethyl acetate, butyl acetate, methyl methoxypropionate, ethyl ethoxypropionate, diethyl oxalate, malon Acid diethyl, 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, dichloromethane 1,2-dichloroethane, 1,4-dichlorobutane, trichloroethane, chlorobenzene, o-dichlorobenzene, hexane, heptane, octane, benzene, toluene, xylene and the like.

  As described above, a reaction solution obtained by dissolving polyamic acid is obtained. The reaction solution is poured into a large amount of poor solvent to obtain a precipitate, and the precipitate is dried under reduced pressure to obtain a polyamic acid. The polyamic acid can be purified by dissolving the polyamic acid again in an organic solvent and then precipitating with a poor solvent once or several times.

<Dehydration ring closure reaction>
The specific polymer constituting the liquid crystal aligning agent of the present invention can be synthesized by dehydrating and cyclizing a part or all of the polyamic acid. The specific polymer used in the present invention, the proportion of the repeating unit having an imide ring in all the repeating units (hereinafter, also referred to as "imidization ratio") is preferably is 40 mol% or more, more preferably 50 mol% That's it. By using a polymer having an imidization ratio of 40 mol% or more, a liquid crystal aligning agent capable of forming a liquid crystal alignment film having a short afterimage erasing time can be obtained.

The polyamic acid is dehydrated and closed by (i) a method of heating the polyamic acid, or (ii) dissolving the polyamic acid in an organic solvent, adding a dehydrating agent and a dehydrating ring-closing catalyst to this solution, and heating as necessary. By the method.
The reaction temperature in the method of heating the polyamic acid (i) is preferably 50 to 200 ° C, more preferably 60 to 170 ° C. When the reaction temperature is less than 50 ° C., the dehydration ring-closing reaction does not proceed sufficiently, and when the reaction temperature exceeds 200 ° C., the molecular weight of the imidized polymer obtained may decrease.

  On the other hand, in the method (ii) of adding a dehydrating agent and a dehydrating ring-closing catalyst to the polyamic acid solution, an acid anhydride such as acetic anhydride, propionic anhydride, or trifluoroacetic anhydride is used as the dehydrating agent. Can do. The amount of the dehydrating agent used depends on the desired imidization ratio, but is preferably 0.01 to 20 mol per 1 mol of the polyamic acid repeating unit. Moreover, as a dehydration ring closure catalyst, tertiary amines, such as a pyridine, a collidine, a lutidine, a triethylamine, can be used, for example. However, it is not limited to these. The amount of the dehydration ring closure catalyst used is preferably 0.01 to 10 moles per mole of the dehydrating agent used. The imidation rate can be increased as the amount of the above dehydrating agent and dehydrating ring-closing agent increases. In addition, as an organic solvent used for dehydration ring closure reaction, the organic solvent illustrated as what is used for the synthesis | combination of a polyamic acid can be mentioned. And reaction temperature of dehydration ring closure reaction becomes like this. Preferably it is 0-180 degreeC, More preferably, it is 10-150 degreeC. Moreover, the obtained specific polymer can be refine | purified by performing operation similar to the purification method of a polyamic acid with respect to the reaction solution obtained in this way.

<End-modified polymer>
The specific polymer used in the present invention may be a terminal-modified type having a controlled molecular weight. By using this terminal-modified polymer, the coating characteristics of the liquid crystal aligning agent can be improved without impairing the effects of the present invention. Such a terminal-modified polymer can be synthesized by adding an acid monoanhydride, a monoamine compound, a monoisocyanate compound or the like to the reaction system when synthesizing a polyamic acid. Here, as the acid monoanhydride, for example, maleic anhydride, phthalic anhydride, itaconic anhydride, n-decyl succinic anhydride, n-dodecyl succinic anhydride, n-tetradecyl succinic anhydride , N-hexadecyl succinic anhydride and the like. Examples of monoamine compounds include aniline, cyclohexylamine, n-butylamine, n-pentylamine, n-hexylamine, n-heptylamine, n-octylamine, n-nonylamine, n-decylamine, and n-undecylamine. N-dodecylamine, n-tridecylamine, n-tetradecylamine, n-pentadecylamine, n-hexadecylamine, n-heptadecylamine, n-octadecylamine, n-eicosylamine, etc. Can do. Examples of the monoisocyanate compound include phenyl isocyanate and naphthyl isocyanate.

<Logarithmic viscosity of polymer>
The polyamic acid obtained as described above preferably has a logarithmic viscosity (η _ln ) of 0.05 to 10 dl / g, more preferably 0.05 to 5 dl / g.
The value of the logarithmic viscosity (η _ln ) in the present invention is determined by measuring the viscosity at 30 ° C. for a solution having a concentration of 0.5 g / 100 ml using N-methyl-2-pyrrolidone as a solvent. ).

[Liquid crystal aligning agent]
The liquid crystal aligning agent of the present invention is constituted by dissolving the specific polymer usually in an organic solvent.
The temperature at the time of preparing the liquid crystal aligning agent of this invention becomes like this. Preferably it is 0 to 200 degreeC, More preferably, it is 20 to 60 degreeC.

Examples of the organic solvent constituting the liquid crystal aligning agent of the present invention include 1-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, 3-butoxy-N, N-dimethylpropanamide, 3-methoxy-N, N-dimethylpropanamide, 3-hexyloxy-N, N-dimethylpropanamide and the like . Among these, 3-butoxy-N, N-dimethylpropanamide and 3-methoxy-N, N-dimethyl exhibiting good printability. propanamide or 3- hexyloxy -N, containing N- dimethylpropanamide.

  The solid content concentration in the liquid crystal aligning agent of the present invention is selected in consideration of viscosity, volatility, etc., but is preferably 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 to form a coating film that becomes a liquid crystal alignment film. When the solid content concentration is less than 1% by weight, the coating film thickness is When the solid content concentration exceeds 10% by weight, the film thickness of the coating film becomes excessive and a good liquid crystal alignment film cannot be obtained. In addition, the viscosity of the liquid crystal aligning agent increases, resulting in poor coating characteristics.

The liquid crystal aligning agent of this invention may contain the functional silane containing compound and the epoxy compound from a viewpoint which improves the adhesiveness with respect to the substrate surface within the range which does not impair the target physical property. Examples of such functional silane-containing compounds include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 2-aminopropyltrimethoxysilane, 2-aminopropyltriethoxysilane, and N- (2-aminoethyl). -3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-ureidopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, N-ethoxycarbonyl-3-amino Propyltrimethoxysilane, N-ethoxycarbonyl-3-aminopropyltriethoxysilane, N-triethoxysilylpropyltriethylenetriamine, N-trimethoxysilylpropyltriethylenetriamine, 10-trimethoxysilyl- , 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-aminopropyltriethoxysilane, N -Bis (oxyethylene) -3-aminopropyltrimethoxysilane, N-bis (oxyethylene) -3-aminopropyltriethoxysilane, etc. can be mentioned. Examples of such epoxy compounds 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. diglycidyl ether, glycerin diglycidyl ether, 2,2-dibromo-neopentyl glycol diglycidyl ether, 1,3,5,6- tetraglycidyl-2,4-hexanediol, N, N, N ', N' - tetraglycidyl -m- xylene diamine, 1,3-bis (N, N-diglycidyl aminomethyl) cyclohexane, N, N, N ', N' - tetraglycidyl-4,4'-Gia Minodiphenylmethane, 3- (N-allyl - N - glycidyl) aminopropyltrimethoxysilane, 3- (N, N-diglycidyl) aminopropyltrimethoxysilane and the like can be mentioned.

<Liquid crystal display element>
The liquid crystal aligning agent of this invention can be used suitably for the liquid crystal display element of a MVA system. The MVA mode indicates a vertical alignment mode in which protrusions are used as alignment regulating means as described in “Liquid Crystal Vol. 3 No. 2 117 (1999)” and Japanese Patent Application Laid-Open No. 11-258605. The protrusions may be formed on the TFT substrate side and the color filter side, respectively, or may have protrusions on the color filter side and slits on the TFT side.
The liquid crystal display element obtained using the liquid crystal aligning agent of this invention can be manufactured, for example with the following method.

(1) The liquid crystal aligning agent of the present invention is applied to one surface of a substrate provided with a patterned transparent conductive film, or a transparent conductive film having protrusions formed as alignment regulating means, for example, roll coater method, spinner method, printing method, etc. Then, the coating is formed by heating the coated surface. 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, or polycarbonate can be used. Further, as a transparent conductive film provided on one surface of the substrate, tin oxide (SnO _{2) is used.} NESA film (registered trademark of PPG, USA), indium oxide-tin oxide (In ₂ O ₃ An ITO film made of —SnO ₂ ) or the like can be used. For patterning these transparent conductive films, a photo-etching method or a method using a mask in advance is used. In addition, a projection structure is formed on the substrate to define the alignment direction of the liquid crystal, and slits are formed in the electrode. An improved liquid crystal display element can be obtained. 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 liquid crystal aligning agent film, a functional silane-containing compound, a functional titanium-containing compound, etc. Can also be applied in advance. Moreover, heating temperature becomes like this. Preferably it is 80-250 degreeC, More preferably, it is 120-200 degreeC. The film thickness of the formed film is preferably 0.001 to 1 μm, and more preferably 0.005 to 0.5 μm. In addition, the liquid crystal aligning agent of this invention forms the film used as a liquid crystal aligning film by removing an organic solvent after application | coating, but also advances dehydration ring closure by further heating and is partially imidized or completely imidized. It can also be a coated film.

(2) Two substrates on which the liquid crystal alignment film is formed as described above are manufactured, arranged to face each other with a gap (cell gap) therebetween, and the peripheral portions of the two substrates are bonded together with a sealant, and the substrate surface Then, liquid crystal is injected and filled in the cell gap defined by the sealing agent, and the injection hole is sealed to form a liquid crystal cell. And a liquid crystal display element is obtained by bonding a polarizing plate to the outer surface of a liquid crystal cell, ie, the other surface side of each board | substrate which comprises a liquid crystal cell.
Here, 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, phenyl cyclohexane liquid crystal, ester liquid crystal, terphenyl liquid crystal, biphenyl cyclohexane liquid crystal, pyrimidine liquid crystal, dioxane liquid crystal, bicyclooctane. Type liquid crystal, cubane type liquid crystal and the like can be used. Further, for these liquid crystals, for example, cholesteric liquid crystals such as cholestyl chloride, cholesteryl nonate, cholesteryl carbonate, and chiral agents such as those sold under the trade names “C-15” and “CB-15” (manufactured by Merck). Etc. can also be used. Furthermore, a ferroelectric liquid crystal such as p-decyloxybenzylidene-p-amino-2-methylbutylcinnamate can also be used.
Further, as a polarizing plate to be bonded to the outer surface of the liquid crystal cell, a polarizing film or an H film in which a polarizing film called an H film that absorbs iodine while sandwiching and stretching polyvinyl alcohol is sandwiched between cellulose acetate protective films. The polarizing plate which consists of itself can be mentioned.

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

[Method for measuring imidation ratio of specific polymer]
The polymer was 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, and determined according to the following formula (ii).
Imidation ratio (%) = (1−A ¹ / A ² × α) × 100 (ii)
A ¹ : Peak area derived from NH group protons (10 ppm)
A ² : Peak area derived from other protons α: Number ratio of other protons to one proton of NH group in polymer precursor (polyamic acid)

[Method for manufacturing liquid crystal display element]
Production of liquid crystal display elements:
As shown in FIG. 1, a liquid crystal aligning agent is printed on a glass substrate with ITO (A) having protrusions formed using a positive resist and a glass substrate (B) having an ITO pattern, respectively. A film having a dry film thickness of 600 Å was formed by drying for 1 minute at 180 ° C. for 1 minute.
Two substrates on which the liquid crystal alignment film was formed as described above were prepared, and an epoxy resin adhesive containing aluminum oxide spheres having a particle size of 3.5 μm was applied to the outer edge of the substrate (B) by screen printing. After the application, the two substrates were bonded so as to have the positional relationship as shown in FIG.
In the cell gap defined by the adhesive on the surface and outer edge of the substrate, a negative type liquid crystal MLC6608 manufactured by Merck & Co. is injected and filled, and then the injection hole is sealed with an epoxy-based adhesive to vertically align liquid crystal display element Was made.

[Vertical alignment evaluation]
The liquid crystal display element at the time of voltage OFF and AC 12V (peak-peak) was observed under crossed Nicols.

[Printability evaluation]
A 127 mm (D) × 127 mm (W) × 1.1 mm (H) glass substrate having an ITO film formed on the entire surface of one side is prepared, and a liquid crystal alignment film coating printer (manufactured by Nissha Printing Co., Ltd.) is prepared on this glass substrate. The liquid crystal aligning agent obtained in the above experiment was filtered through a microfilter having a pore size of 0.2 μm using Angstromer S-40L), and then applied to the transparent electrode surface. It dried with the hotplate close contact type preliminary dryer set to 80 degreeC, and baked for 60 minutes at 200 degreeC, and formed the liquid crystal aligning film on the glass substrate with an ITO film | membrane. The number of repelled prints in the center 10 cm ² of the obtained film was examined to evaluate the number of repels.

[Evaluation of uniformity of coating film printed with liquid crystal aligning agent]
Using a stylus type film thickness meter, the average film thickness of the coating film and the difference (variation) between the maximum film thickness and the minimum film thickness were measured.

<Synthesis of specific polymer>
Synthesis Examples 1-7
The composition shown in Table 1 is added to N-methyl-2-pyrrolidone in the order of diamine and tetracarboxylic dianhydride, followed by reaction at a solid content concentration of 20% at 60 ° C. for 6 hours. The polyamic acid which has was obtained.

TCAAH: 2,3,5-tricarboxycyclopentyl acetic acid dianhydride CB: 1,2,3,4-cyclobutanetetracarboxylic anhydride MTDA: 1,3,3a, 4,5,9b-hexahydro-8-methyl -5- (Tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-C] furan-1,3-dione PDA: p-phenylenediamine ODA: octadecanoxy-2,4-diaminobenzenediamine [ 1]: Diamine diamine represented by formula (9) [2]: Diamine diamine represented by formula (10) [3]: Diamine represented by formula (13)

Synthesis Examples 8-17
The polyamic acid obtained in Synthesis Examples 1 to 7 was diluted with N-methyl-2-pyrrolidone to a solid content concentration of 5%, pyridine and acetic anhydride were added as catalysts shown in Table 2, and the mixture was stirred at 110 ° C. for 4 hours. Thus, a specific polymer was synthesized. The polymer solution was reprecipitated with diethyl ether to obtain a white powder of a polymer (imidized polymer). Table 2 also shows the imidization ratio of the obtained specific polymer. In Table 2, pyridine / acid anhydride (times mole) = 1.0 / 1.0 means 1.0 mole of pyridine and 1.0 mole of acetic anhydride with respect to 1.0 mole of amide bond in polyamic acid. Is added.

Synthesis Examples 18 to 27
The composition shown in Table 3 was added to N-methyl-2-pyrrolidone in the order of diamine and tetracarboxylic dianhydride and reacted at a solid content concentration of 20% at 60 ° C. for 6 hours. The polyamic acid which has was obtained.

TDA: 1,3,3a, 4,5,9b-Hexahydro-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-C] furan-1,3-dione MTDA: 1 , 3,3a, 4,5,9b-Hexahydro-8-methyl-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] -furan-1,3-dione TNA : 3,5,6-tricarbonyl-2-carboxynorbornane-2: 3,5: 6-dianhydride CHA: acid anhydride DDE represented by formula (1): 4,4'-diaminodiphenyl ether diamine [ 2]: Diamine diamine represented by formula (10) [4]: Diamine diamine represented by formula (21) [5]: Diamine diamine represented by formula (17) [6]: In formula (16) Diamine represented

Synthesis Examples 28 to 39
The obtained polyamic acid was diluted with N-methyl-2-pyrrolidone to a solid content concentration of 5%, pyridine and acetic anhydride shown in Table 4 were added as a catalyst, and the mixture was stirred at 110 ° C. for 4 hours to give a specific polymer. Synthesized. The polymer solution was reprecipitated with diethyl ether to obtain a white powder of a polymer (imidized polymer). Table 4 shows the imidization ratio of the obtained specific polymer. In Table 4, pyridine / acid anhydride (times mole) = 1.0 / 1.0 means 1.0 mole of pyridine and 1.0 mole of acetic anhydride with respect to 1.0 mole of amide bond in polyamic acid. Is added.

Examples 1-40, Reference Examples 1-4
The specific polymers obtained in Synthesis Examples 8 to 17 were prepared with solvents having various compositions shown in Table 5 to a solid content concentration of 6.0% to obtain the vertical alignment type liquid crystal aligning agent of the present invention. A liquid crystal display element was produced using this liquid crystal aligning agent, and various evaluations were performed. The results are shown in Table 5. Examples 1, 5, 9, 13, 17, 21, 25, 29, 33, and 37 are also reference examples.

The types of solvents in Table 5 are as follows.
(A) N-methyl-2-pyrrolidone (b) 3-butoxy-N, N-dimethylpropanamide (c) 3-methoxy-N, N-dimethylpropanamide (d) 3-hexyloxy-N, N- Dimethylpropanamide (e) butyl cellosolve

Examples 41-72, Reference Examples 5-6
The specific polymers obtained in Synthesis Examples 28 to 39 were added to the additives shown in Table 6 (N, N, N ′, N′-tetraglycidyl-4,4′-diaminodiphenylmethane, hereinafter abbreviated as EP) and various compositions. Was used to obtain a solid content concentration of 6.0% to obtain a vertical alignment type liquid crystal alignment agent of the present invention. A liquid crystal display element was produced using this liquid crystal aligning agent, and various evaluations were performed. The results are shown in Table 6. Examples 41, 43, 45, 47, 49, 51, 53, 55, 57, 59, 61, 63, 65, 67, 69 and 71 are also reference examples.

The types of solvents in Table 6 are as follows.
(A) N-methyl-2-pyrrolidone (b) 3-butoxy-N, N-dimethylpropanamide (c) 3-methoxy-N, N-dimethylpropanamide (d) 3-hexyloxy-N, N- Dimethylpropanamide (e) butyl cellosolve

Explanatory drawing of preparation of the liquid crystal display element in an Example.

Claims (4)

Having the formula at least one recurring unit of selected from the group consisting of repeating units represented by repeating units and formula represented by (I-1) (I- 2) and have a repeating unit having an imide ring The polymer to be dissolved is contained in an organic solvent, provided that the organic solvent is 3-butoxy-N, N-dimethylpropanamide, 3-methoxy-N, N-dimethylpropanamide or 3-hexyloxy-N , N-dimethylpropanamide , a vertical alignment type liquid crystal aligning agent characterized by the above-mentioned.

(In the formula, P ¹ is a tetravalent organic group, and Q ¹ is a group represented by the following formula (Q-1) or (Q-2).)

(In the formula, P ² is a tetravalent organic group, and Q ² is a group represented by the following formula (Q-1) or (Q-2).)

(In the formula, X consists of —O—, —CO—, —COO—, —OCO—, —NHCO—, —CONH—, —S—, a methylene group, an alkylene group having 2 to 6 carbon atoms, and a phenylene group. R ¹ is a divalent group selected from the group, and R ¹ represents an alkyl group having 10 to 20 carbon atoms, a monovalent organic group having an alicyclic skeleton having 4 to 40 carbon atoms, or a fluorine atom having 6 or more carbon atoms. A monovalent organic group.)

(In the formula, X consists of —O—, —CO—, —COO—, —OCO—, —NHCO—, —CONH—, —S—, a methylene group, an alkylene group having 2 to 6 carbon atoms, and a phenylene group. (It is a divalent group selected from the group, and R ² is a divalent organic group having an alicyclic skeleton having 4 to 40 carbon atoms.) The liquid crystal aligning agent of Claim 1 whose said polymer has 40 mol% or more of repeating units which have an imide ring in all the repeating units. The liquid crystal display element characterized by including the liquid crystal alignment film obtained by using the vertical alignment type liquid crystal aligning agent according to claim 1 or 2. 3. The liquid crystal aligning agent according to claim 1 or 2 is applied on one surface of a substrate provided with a patterned transparent conductive film, or on a transparent conductive film on which protrusions as alignment regulating means are formed. A method for forming a vertical alignment type liquid crystal alignment film, which comprises a step of heating the substrate.

Images