JP2005037920A - Liquid crystal alignment agent, liquid crystal alignment layer, and liquid crystal display element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal alignment agent by which a liquid crystal alignment layer having excellent liquid crystal alignability can be formed. <P>SOLUTION: The liquid crystal alignment agent contains a polyamic acid and/or a polyimide obtained from a tetracarboxylic acid dianhydride having a specified structure or a diamine having a specified structure. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a liquid crystal alignment agent, a liquid crystal alignment film obtained therefrom, and a liquid crystal display device comprising the liquid crystal alignment film.

Conventionally, a cell of a sandwich structure is formed by forming a nematic liquid crystal layer having positive dielectric anisotropy between two substrates having a liquid crystal alignment film formed on the surface via a transparent conductive film, There is known a TN liquid crystal display element having a TN (Twisted Nematic) type liquid crystal cell in which the major axis of liquid crystal molecules is continuously twisted by 90 degrees from one substrate toward the other substrate.
Further, the addition of a chiral agent achieves a state in which the major axis of the liquid crystal molecules is continuously twisted between the substrates by 180 degrees or more, and an STN (Super Twisted Nematic) type liquid crystal display element utilizing the birefringence effect generated thereby. Is also present. More recently, a horizontal electric field type liquid crystal display element that controls liquid crystal molecules by generating an electric field parallel to the substrate surface, a nematic liquid crystal layer in a homeotropic alignment state having a negative dielectric anisotropy between opposing substrates, and a spiral A guest-host type reflective liquid crystal display element in which a cholesteric liquid crystal layer having an axis parallel to the substrate normal is formed and a dye is added to the liquid crystal layer has been developed. The alignment of the liquid crystal in these liquid crystal display elements is usually expressed by a liquid crystal alignment film subjected to a rubbing treatment. Here, conventionally known polyimide, polyamide, polyester and the like are known as liquid crystal alignment film materials constituting the liquid crystal display element. In particular, polyimide is used in many liquid crystal display elements because of its excellent heat resistance, affinity with liquid crystals, mechanical strength, and the like.

A liquid crystal display element is used for a screen of a television or a notebook personal computer because of its thinness and lightness. In recent years, it has become a problem how beautiful images can be displayed.
One of the causes of image deterioration is a defect in the alignment of liquid crystal molecules forming the liquid crystal display element. The alignment of the liquid crystal molecules is expressed by the liquid crystal alignment film formed using the liquid crystal alignment agent, but the conventional liquid crystal alignment film is sufficiently aligned with the narrowing of the pixels due to high definition and high aperture ratio. There was a problem that the arrangement could not be performed.

The present invention has been made in view of the above-described circumstances, and aims to provide a liquid crystal display element excellent in liquid crystal alignment, a liquid crystal alignment film provided therein, and a liquid crystal alignment agent for forming the liquid crystal alignment film. It is a thing.
The above objects and advantages of the present invention are as follows. First, a polymer having at least one selected from repeating units represented by the following formulas (1) to (4) (hereinafter also referred to as “repeating unit A”) , Also referred to as “specific polymer”).

(In the formula, Q and R represent different tetravalent organic groups, and X and Y represent different divalent organic groups.)

  Secondly, the above-mentioned objects and advantages of the present invention are as follows: a tetracarboxylic dianhydride represented by the following formula (i) (hereinafter also referred to as “tetracarboxylic dianhydride (i)”) and a diamine. This is achieved by a liquid crystal aligning agent characterized by containing the resulting polymer.

  Thirdly, the above object and advantage of the present invention include a polymer obtained from a diamine represented by the following formula (ii) (hereinafter also referred to as “diamine (ii)”) and tetracarboxylic dianhydride. It is achieved by a liquid crystal aligning agent characterized by containing.

Fourth, the above objects and advantages of the present invention are achieved by a liquid crystal alignment film obtained from the liquid crystal aligning agent of the present invention.
Fifthly, the above objects and advantages of the present invention are achieved by a liquid crystal display device comprising the liquid crystal alignment film of the present invention.

ADVANTAGE OF THE INVENTION According to this invention, the liquid crystal aligning agent which can form the liquid crystal aligning film excellent in transparency can be provided.
The liquid crystal alignment film formed by the liquid crystal aligning agent of the present invention is preferably used for constituting various transmissive and reflective liquid crystal display elements such as guest-host type liquid crystal display elements as well as TN type and STN type. Can do. Further, the liquid crystal display element provided with the liquid crystal alignment film has excellent image quality and can be effectively used in various devices. For example, the liquid crystal display device is suitably used as a display device such as a desk calculator, a wristwatch, a counting display board, and a mobile computer. be able to.

Hereinafter, the present invention will be described in detail.
The specific polymer used in the present invention contains a specific repeating unit. The content ratio of the repeating unit A in the specific polymer is preferably 20 to 100 mol%, more preferably 50 to 100 mol%, and particularly preferably 100 mol%. The number of repeating units A is usually 1 to 100,000, preferably 5 to 20000, and more preferably 10 to 5000 from the viewpoint of expressing good liquid crystal alignment.

[Specific polymer]
The specific polymer used in the present invention can be usually produced using one of the following two methods.
I A method of ring-opening polymerization of tetracarboxylic dianhydride (i) and a diamine to obtain a polyamic acid, and dehydrating and ring-closing if necessary (hereinafter also referred to as “Method I”).
II A method of ring-opening polymerization of tetracarboxylic dianhydride and diamine (ii) to obtain a polyamic acid, and if necessary, dehydrating and ring-closing (hereinafter also referred to as “Method II”).
Usually, the polyamic acid obtained by Method I has a repeating unit represented by the above formula (1), and the imidized polymer obtained by dehydrating and ring-closing this has a repeating unit represented by the above formula (2). Have. Further, the polyamic acid obtained by Method II has a repeating unit represented by the above formula (3), and the imidized polymer obtained by dehydrating and ring-closing this has a repeating unit represented by the above formula (4). Have.

[Tetracarboxylic dianhydride (i)]
The tetracarboxylic dianhydride (i) used in Method I is a compound represented by the above formula (i). Q in the above formula (i) is a tetravalent organic group, for example, an aromatic-containing group such as benzene, naphthalene, anthracene, biphenyl skeleton, benzophenone skeleton; cyclobutane, cyclopentane, cyclohexane, norbornane, tricyclodecane, tetra And alicyclic groups such as cyclododecane; aliphatic groups such as butane, pentane and hexane. These groups may be substituted with a halogen atom, an alkyl group, a halogenated alkyl group, an alkoxyl group or the like, and the number of substituents may be one or plural. Preferable examples include a group represented by the following formula and a group in which one or more hydrogen atoms in these structures are substituted with the above substituents, preferably a fluorine atom, a methyl group, or a trifluoromethyl group. It is done.

  X in the formula (i) is a divalent organic group, for example, an aromatic-containing group such as a phenylene group, a naphthylene group, a biphenylene group, a bisphenol A skeleton, a bisphenol F skeleton, a benzophenone skeleton, a chalcone skeleton, or a cinnamoyl skeleton; Examples include alicyclic groups such as cyclobutane, cyclopentane, cyclohexane, norbornane, tricyclodecane, and tetracyclododecane; and aliphatic groups such as butane, pentane, and hexane. These groups may be substituted with a halogen atom, an alkyl group, a halogenated alkyl group, an alkoxyl group or the like, and the number of substituents may be one or plural. Preferable examples include a group represented by the following formula and a group in which one or more hydrogen atoms in these structures are substituted with the above substituents, preferably a fluorine atom, a methyl group, or a trifluoromethyl group. It is done.

  As a synthesis method of tetracarboxylic dianhydride (i), 1 mol of diamine represented by the following formula (i-1) and 3 mol of tetracarboxylic dianhydride represented by the following formula (i-2) The above is mixed in a polar solvent such as N-methyl-2-pyrrolidone and reacted at −15 to 100 ° C. Then, pyridine and acetic anhydride are added to the polar solvent in which the obtained compound is dissolved. The tetracarboxylic dianhydride (i) can be obtained by a method of adding and dehydrating and ring-closing under heating.

  Examples of the diamine represented by the formula (i-1) include p-phenylenediamine, m-phenylenediamine, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylethane, and 4,4′-diamino. Diphenyl sulfide, 4,4′-diaminodiphenyl sulfone, 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-trimethylindane, 3,4′-diaminodiphenyl ether, 3,3′-diaminobenzophenone, 3,4′-diaminobenzof Non, 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-4,4′-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, aromatic diamines such as 4,4′-bis [(4-amino-2-trifluoromethyl) phenoxy] -octafluorobiphenyl;

1,1-metaxylylenediamine, 1,3-propanediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, 4,4-diaminoheptamethylenediamine, 1 , 4-diaminocyclohexane, isophorone diamine, tetrahydrodicyclopentadienylenediamine, hexahydro-4,7-methanoindanylene methylene diamine, tricyclo [6.2.1.02,7] -undecylenedimethyl diamine, 4, Aliphatic and cycloaliphatic diamines such as 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-diaminopurine 5,6-diamino-1,3 Dimethyluracil, 3,5-diamino-1,2,4-triazole, 6,9-diamino-2-ethoxyacridine lactate, 3,8-diamino-6-phenylphenanthridine, 1,4-diaminopiperazine, 3, , 6-diaminoacridine, bis (4-aminophenyl) phenylamine, and compounds represented by the following formulas (III) to (IV), etc. A diamine having a nitrogen atom;

(In the formula, R ⁵ represents a monovalent organic group having a ring structure containing a nitrogen atom selected from pyridine, pyrimidine, triazine, piperidine and piperazine, and X represents a divalent organic group.)

Wherein R ⁶ represents a divalent organic group having a ring structure containing a nitrogen atom selected from pyridine, pyrimidine, triazine, piperidine and piperazine, X represents a divalent organic group, and a plurality of X May be the same or different.)

Monosubstituted phenylenediamines represented by the following formula (V); diaminoorganosiloxanes represented by the following formula (VI);

(Wherein R ⁷ represents a divalent organic group selected from —O—, —COO—, —OCO—, —NHCO—, —CONH— and —CO—, and R ⁸ represents a steroid skeleton, A monovalent organic group having a group selected from a fluoromethyl group and a fluoro group or an alkyl group having 6 to 30 carbon atoms is shown.)

(Wherein R ⁹ represents a hydrocarbon group having 1 to 12 carbon atoms, and a plurality of R ⁹ may be the same or different, p is an integer of 1 to 3, and q is 1 to 20) Is an integer.)

Examples include compounds represented by the following formulas (9) to (13).

(In the formula, y is an integer of 2 to 12, and z is an integer of 1 to 5.)

  Of 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-aminophenoxy) Benzene, 4,4′-bis (4-aminophenoxy) biphenyl, compounds represented by the above formulas (9) to (13), 2,6-diaminopyridine, 3,4-diaminopyridine, 2,4-diamino Pyrimidine, 3,6-diaminoacridine, a compound represented by the following formula (14) among the compounds represented by the above formula (III), and a compound represented by the following formula (15) among the compounds represented by the above formula (IV) Of the compounds represented by the formula (V), the compounds represented by the following formulas (16) to (21) are preferred.

  Examples of the tetracarboxylic dianhydride represented by the above formula (i-2) include butanetetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2- Dimethyl-1,2,3,4-cyclobutanetetracarboxylic 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-cyclopentanetetra Carboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, 3,3 ′, 4,4′-dicyclohexyltetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentylacetic acid Dianhydride, 3,5,6-tricarboxynorborn Nan-2-acetic acid 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), aliphatic and alicyclic tetracarboxylic dianhydrides such as compounds represented by the following formulas (I) and (II);

(Wherein R ¹ and R ³ represent a divalent organic group having an aromatic ring, R ² and R ⁴ represent a hydrogen atom or an alkyl group, and a plurality of R ² and R ⁴ are the same. But it may be different.)

Pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenylsulfone tetracarboxylic dianhydride, 1,4,5, 8-naphthalenetetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic 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-dicarboxyphenoxy) diph Nylpropane dianhydride, 3,3 ′, 4,4′-perfluoroisopropylidene diphthalic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, bis (phthalic acid) phenyl Phosphine 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 (anhydrotrimellitate), propylene glycol-bis (anhydrotrimellitate), 1,4- Butanediol-bis (anhydrotrimellitate), 1,6-hexanediol-bis (anhydrotrimellitate), 1,8-o Fragrances such as kutandiol-bis (anhydrotrimellitate), 2,2-bis (4-hydroxyphenyl) propane-bis (anhydrotrimellitate), compounds represented by the following formulas (1) to (4) Group tetracarboxylic dianhydride.

  Of these, butanetetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentylacetic acid dianhydride, 5- ( 2,5-dioxotetrahydrofural) -3-methyl-3-cyclohexene-1,2-dicarboxylic 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- ] 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), pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic acid Dianhydrides, 3,3 ′, 4,4′-biphenylsulfonetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, compounds of the above formula (I) Among the compounds represented by the following formulas (5) to (7) and the compound represented by the above formula (II) The compound represented by the formula (8) is preferable from the viewpoint of exhibiting good liquid crystal alignment, and particularly preferable is 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentylacetic acid dianhydride, 1,3,3a, 4,5,9b-hexahydro-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] furan-1,3-dione, 1,3, 3a, 4,5,9b-Hexahydro-8-methyl-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] furan-1,3-dione, 3-oxabicyclo [3.2.1] Octane-2,4-dione-6 Pyro -3 '- (tetrahydrofuran-2', 5'-dione), may be mentioned compounds represented by pyromellitic dianhydride and the following formula (5).

等が挙げられる。

Etc.

  As the diamine that can be used for the ring-opening polymerization with the tetracarboxylic dianhydride (i), the above-mentioned compounds can be used, but it is possible to select a compound having a structure different from the structure selected as X. desirable.

[Diamine (ii)]
The diamine (ii) used in Method II is a compound represented by the above formula (ii). Preferred structures of Q and X in the above formula (ii) are the same as the preferred structures of Q and X in the above formula (i).

Examples of the synthesis method of diamine (ii) include the following three synthesis methods.
<Synthesis Method 1>
1 mol of a tetracarboxylic dianhydride represented by the following formula (ii-1) and 2 mol or more of a nitro group-containing monoamine represented by the following formula (ii-2), N-methyl-2-pyrrolidone, etc. The dinitro compound having an amic acid structure was synthesized by mixing in a polar solvent and reacting at −15 to 100 ° C., and then pyridine and acetic anhydride were dissolved in the polar solvent in which the obtained dinitro compound was dissolved. And dehydrating and ring-closing under heating to obtain an imide group-containing dinitro compound. Thereafter, the imide group-containing dinitro compound obtained is dissolved in a solvent such as ethyl alcohol and the nitro group is reduced using hydrogen gas or the like, whereby the desired diamine (ii) can be obtained.

<Synthesis Method 2>
A polar solvent such as N-methyl-2-pyrrolidone containing 1 mol of tetracarboxylic dianhydride represented by the above formula (ii-1) and 3 mol or more of a diamine represented by the following formula (ii-3) After mixing and reacting at −15 to 100 ° C., pyridine and acetic anhydride are added to a polar solvent in which the obtained compound is dissolved, and dehydration and cyclization are carried out under heating, whereby an imide group-containing diester is obtained. An acetamide compound is obtained. Then, diamine (ii) can be obtained by processing the obtained imide group-containing diacetamide compound with an alkali such as an aqueous sodium hydroxide solution.

<Synthesis Method 3>
1 mol of a tetracarboxylic dianhydride represented by the above formula (ii-1) and 2 mol or more of a nitro group-containing monoisocyanate compound represented by the following formula (ii-4) An imide group-containing dinitro compound is synthesized by mixing in a polar solvent such as pyrrolidone and reacting at 60 to 150 ° C. Next, the diamine (ii) is obtained by dissolving the obtained dinitro compound in a solvent such as ethyl alcohol and reducing the nitro group using hydrogen gas or the like.

  Examples of the tetracarboxylic dianhydride represented by the above formula (ii-1) include the tetracarboxylic dianhydrides described above. Examples of the diamine represented by the above formula (ii-3) include the diamines described above. Moreover, the nitro group-containing monoamine represented by the above formula (ii-2) and the nitro group-containing monoisocyanate represented by the above formula (ii-4) include those of the diamine represented by the above formula (ii-3). A compound having a structure in which the amino group is replaced with a nitro group or an isocyanato group, respectively.

  As the tetracarboxylic dianhydride that can be used for ring-opening polymerization with this specific diamine, for example, the compounds described below can be used, but a compound having a structure different from the structure selected as Q is selected. It is desirable.

[Polyamic acid]
The polyamic acid containing the repeating unit represented by the above formula (1) or (3) can be produced using the above method I or II. The ratio of the tetracarboxylic dianhydride and the diamine used at this time is such that the acid anhydride group of the tetracarboxylic dianhydride is 0.2 to 2 equivalents relative to 1 equivalent of the amino group contained in the diamine. The ratio is preferably 0.6 to 1.5 equivalents, more preferably 0.9 to 1.2.

  This reaction is usually carried out in an organic solvent under a temperature condition of -20 to 150 ° C, preferably 0 to 100 ° C. Here, the organic solvent is not particularly limited as long as it can dissolve both the raw material diamine and tetracarboxylic dianhydride and the synthesized polyamic acid. Preferred examples include N-methyl-2-pyrrolidone, Aprotic polar solvents such as N, N-dimethylacetamide, N, N-dimethylformamide, dimethylsulfoxide, 1,3-dimethyl-2-imidazolidone, γ-butyrolactone, tetramethylurea, hexamethylphosphortriamide; m- Phenol solvents such as cresol, xylenol, phenol and halogenated phenol can be exemplified. The amount of organic solvent used (a) is such that the total amount (b) of tetracarboxylic dianhydride and diamine is usually 0.1 to 40% by weight based on the total amount (a + b) of the reaction solution. An amount is preferred.

For the organic solvent, alcohols, ketones, esters, ethers, halogenated hydrocarbons, hydrocarbons, etc., which are poor solvents for polyamic acid, are used in combination as long as the polyamic acid to be produced does not precipitate. be able to. Specific examples of such a poor solvent include, for example, methyl alcohol, ethyl alcohol, isopropyl alcohol, cyclohexanol, 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, diethyl malonate, diethyl ether, ethylene glycol monomethyl ether, Ethylene glycol monoethyl ether, ethylene glycol mono-n-propyl ether, ethylene glycol mono-i-propyl ether, ethylene Recall mono-n-butyl ether, ethylene glycol dimethyl ether, ethylene glycol methyl ethyl 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, diacetone alcohol, propylene carbonate, propylene glycol Monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, propylene glycol monomethyl ether, and the like α- pinene.
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.

[Polyimide]
The polyimide containing the repeating unit represented by the above formula (2) or (4) can be obtained using a conventional method for producing polyimide. In addition, the polyimide which is a specific polymer used by this invention may have a low imidation rate. Here, the “imidation ratio” is the percentage of the number of repeating units that form an imide ring with respect to the total number of repeating units in the polymer. At this time, a part of the imide ring may be an isoimide ring. The imidation ratio can be adjusted by adjusting the conditions for the dehydration ring-closing reaction.
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 (i) of heating the polyamic acid is usually 100 to 300 ° C, preferably 150 to 250 ° C. When the reaction temperature is less than 100 ° C., the dehydration ring-closing reaction does not proceed sufficiently, and when the reaction temperature exceeds 300 ° C., the molecular weight of the imidized polymer obtained may decrease.
On the other hand, in the method of adding a dehydrating agent and a dehydrating ring-closing catalyst to the polyamic acid solution of (ii) above, as the dehydrating agent, for example, an acid anhydride such as acetic anhydride, propionic anhydride, or trifluoroacetic anhydride is used. Can do. The amount of the dehydrating agent used is preferably 0.01 to 20 mol with respect to 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. 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 the reaction temperature of dehydration ring closure reaction is 0-180 degreeC normally, Preferably it is 10-150 degreeC. Moreover, a polyimide can be refine | purified by performing operation similar to the purification method of polyamic acid with respect to the reaction solution obtained in this way.

[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.
As an organic solvent which comprises the liquid crystal aligning agent of this invention, the solvent illustrated as what is used for the synthesis reaction of a polyamic acid can be mentioned. Moreover, the poor solvent illustrated as what can be used together in the case of the synthesis reaction of a polyamic acid can also be selected suitably, and can be used together.
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. Moreover, the temperature at the time of preparing the liquid crystal aligning agent of this invention is 0 degreeC-200 degreeC normally, Preferably it is 20 degreeC-60 degreeC.

  The liquid crystal aligning agent of the present invention may contain a functional silane-containing compound or an epoxy group-containing compound from the viewpoint of improving the adhesion to the substrate surface. 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- Aminopropyltrimethoxysilane, 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 the epoxy group-containing compound include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1, 6-hexanediol diglycidyl ether, glycerin diglycidyl ether, 2,2-dibromoneopentylglycol diglycidyl ether, 1,3,5,6-tetraglycidyl-2,4-hexanediol, N, N, N ′, N ′,-tetraglycidyl-m-xylenediamine, 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, N, N, N ′, N ′,-tetraglycidyl , And the like as preferred 4,4'-diaminodiphenylmethane. The compounding ratio of these functional silane-containing compounds and epoxy group-containing compounds is usually 40 parts by weight or less, preferably 0.1 to 30 parts by weight with respect to 100 parts by weight of the polymer.

[Liquid crystal display element]
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 by a method such as a roll coater method, a spinner method, or a printing method, and then the coated surface is heated. Thus, a coating film is formed. 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. As the 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. For patterning these transparent conductive films, a photo-etching method or a method using a mask in advance is 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-containing compound, a functional titanium-containing compound, or the like is previously applied to the surface of the substrate. You can also The heating temperature after application of the liquid crystal aligning agent is 80 to 300 ° C, preferably 120 to 250 ° C. In addition, the liquid crystal aligning agent of the present invention containing a polyamic acid forms a coating film that becomes an alignment film by removing the organic solvent after coating, but further proceeds with dehydration ring closure by further heating, and is further imidized. It can also be set as a coating film. The film thickness of the coating film to be formed is usually 0.001 to 1 μm, preferably 0.005 to 0.5 μm.

(2) A rubbing process is performed in which the formed coating film surface is rubbed in a certain direction with a roll wound with a cloth made of a fiber such as nylon, rayon, or cotton. Thereby, the orientation ability of a liquid crystal molecule is provided to a coating film, and it becomes a liquid crystal aligning film.
Further, by partially irradiating the liquid crystal alignment film formed of the liquid crystal alignment agent of the present invention with ultraviolet rays as disclosed in, for example, JP-A-6-222366 and JP-A-6-281937. A resist film is partially formed on the surface of the liquid crystal alignment film that has been subjected to a treatment for changing the pretilt angle or a rubbing treatment as disclosed in JP-A-5-107544, which is different from the previous rubbing treatment. The visibility characteristics of the liquid crystal display element can be improved by removing the resist film after performing the rubbing treatment in the direction and changing the liquid crystal alignment ability of the liquid crystal alignment film.

(3) Two substrates on which the liquid crystal alignment film is formed as described above are manufactured, and the two substrates are separated by a gap (cell gap) so that the rubbing directions in the respective liquid crystal alignment films are orthogonal or antiparallel. ), And the periphery of the two substrates are bonded together using a sealant, and liquid crystal is injected and filled in the cell gap defined by the substrate surface and the sealant, and the injection hole is sealed. A liquid crystal cell is constructed. A polarizing plate is disposed on the outer surface of the liquid crystal cell, that is, on the other surface side of each substrate constituting the liquid crystal cell, and the polarization direction thereof coincides with or is orthogonal to the rubbing direction of the liquid crystal alignment film formed on one surface of the substrate. A liquid crystal display element is obtained by pasting together.

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 liquid crystals include nematic liquid crystals, such as Schiff base liquid crystals, azoxy liquid crystals, biphenyl liquid crystals, phenyl cyclohexane liquid crystals, ester liquid crystals, terphenyl liquid crystals, biphenyl cyclohexane liquid crystals, pyrimidine liquid crystals, dioxanes. Type 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.
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.
The liquid crystal alignment properties of the liquid crystal alignment films of Examples and Comparative Examples were evaluated by driving a liquid crystal display element with a rectangular wave of 5 V and 60 Hz for 24 hours and visually observing the presence or absence of display defects.

The specific acid anhydride and specific diamine used in the production of the polyamic acid or polyimide used in Examples and Comparative Examples were performed using compounds having the following structures.
Specific acid anhydride: a compound having the structure represented by Table 1 in which Q and X are represented by the above formula (i).
Specific diamine: a compound having the structure represented by Table 1 in the formula (ii), Q and X.
In Table 1, Q1 to Q7 represent the following tetravalent groups, and X1 to X2 represent the following divalent groups.

[Synthesis of Specific Acid Anhydride I]
To 30 g (0.13 mol) of 2,3,5-tricarboxycyclopentylacetic acid dianhydride, 150 ml of N-methyl-2-pyrrolidone was added and stirred at 60 ° C. to prepare Solution 1. Solution 2 was prepared by adding 15 ml of N-methyl-2-pyrrolidone to 2.8 g (0.014 mol) of 4,4′-diaminodiphenylmethane and stirring.
Solution 1 was heated to 60 ° C., solution 2 was slowly added dropwise with vigorous stirring, and reacted for 6 hours. To this reaction solution, 4.8 g (0.059 mol) of sodium acetate and 55 g (0.54 mol) of acetic anhydride were added and stirred for 4 hours while heating to 100 ° C. The obtained reaction solution was poured into a large excess of water to precipitate the reaction product. Then, 7 g of a mixture of tetracarboxylic acid containing an imide group and a derivative thereof was obtained by drying at 40 ° C. under reduced pressure for 15 hours. 7 g of this mixture and 50 g of acetic anhydride were stirred at 100 ° C. for 6 hours and concentrated under reduced pressure to obtain 7 g of specific acid anhydride I. The analysis results are shown below.
_{1H-NMR (DMSO-d 6} , δm): 1.0-4.0 (18H, m), 7.0-7.7 (8H, m)
The specific acid anhydrides II to VIII were synthesized in the same manner as the specific acid anhydride I.

[Synthesis of Specific Diamine I]
2,42,42 g (0.1 mol) of 2,3,5-tricarboxycyclopentylacetic acid dianhydride and 22.83 g (0.1 mol) of 4-nitro-4′-aminodiphenylmethane were mixed with N-methyl-2-pyrrolidone. It was dissolved in 400 g and reacted at 60 ° C. for 6 hours. Subsequently, 40 g (0.51 mol) of pyridine and 51 g (0.51 mol) of acetic anhydride were added to the resulting reaction solution, followed by dehydration and ring closure at 110 ° C. for 4 hours. Thereafter, the obtained reaction solution was poured into a large amount of methyl alcohol to precipitate the reaction product. Thereafter, 50 g of the obtained imide group-containing dinitro compound was dissolved in 5000 g of ethyl alcohol, 17.5 g of a palladium-on-carbon catalyst (palladium concentration 5% by weight) was added to this solution, and heated for 6 hours while blowing hydrogen gas. Reflux was performed. Thereafter, the catalyst was removed by hot filtration, and the filtrate was cooled to room temperature. The precipitate was filtered off and recrystallized with ethyl alcohol to obtain 27.9 g of specific diamine I.
Specific diamines II to IV were synthesized in the same manner as specific diamine I.

[Synthesis Example 1]
610.6 g (1.0 mol) of specific acid anhydride I as tetracarboxylic dianhydride and 108.1 g (1.0 mol) of p-phenylenediamine as diamine were dissolved in 4500 g of N-methyl-2-pyrrolidone. And reacted at 60 ° C. for 6 hours. The reaction solution was then poured into a large excess of methyl alcohol to precipitate the reaction product. Thereafter, it was washed with methyl alcohol and dried at 40 ° C. under reduced pressure for 15 hours to obtain 650 g of polyamic acid (this is referred to as “polyamic acid (Aa-1)”). 30 g of the resulting polyamic acid was dissolved in 570 g of N-methyl-2-pyrrolidone, 23 g of pyridine and 18 g of acetic anhydride were added, dehydration and ring closure were performed at 110 ° C. for 4 hours, precipitation, washing and decompression were performed in the same manner as described above. 17 g of polyimide having a logarithmic viscosity of 0.85 dl / g and an imidization ratio of 90% (hereinafter referred to as “polyimide (Ab-1)”) was obtained.

[Synthesis Example 2]
Except for using 610.6 g (1.0 mol) of the specific acid anhydride I as the tetracarboxylic dianhydride and 212.3 g (1 mol) of 4,4′-diamino-3,3′-dimethylbiphenyl as the diamine. In the same manner as in Synthesis Example 1, 761 g of polyamic acid (referred to as “polyamic acid (Aa-2)”) was obtained.
Thereafter, a polyimide having a logarithmic viscosity of 0.63 dl / g and an imidization ratio of 87% was obtained in the same manner as in Synthesis Example 1 except that the polyamic acid (Aa-2) was used instead of the polyamic acid (Aa-1). 18 g of “polyimide (Ab-2)” was obtained.

[Synthesis Example 3]
In the same manner as in Synthesis Example 1, except that 762.8 g (1.0 mol) of the specific acid anhydride II was used as the tetracarboxylic dianhydride and 108.1 g (1.0 mol) of p-phenylenediamine was used as the diamine, 812 g of polyamic acid (referred to as “polyamic acid (Aa-3)”) was obtained.
Thereafter, a polyimide having a logarithmic viscosity of 0.46 dl / g and an imidation ratio of 94% was obtained in the same manner as in Synthesis Example 1 except that the polyamic acid (Aa-3) was used instead of the polyamic acid (Aa-1). 18 g of “polyimide (Ab-3)” was obtained.

[Synthesis Example 4]
Synthesis Example 1 except that 672.6 g (1.0 mol) of the specific acid anhydride III was used as the tetracarboxylic dianhydride and 198.3 g (1.0 mol) of 4,4′-diaminodiphenylmethane was used as the diamine. Similarly, 813 g of polyamic acid (this is referred to as “polyamic acid (Aa-4)”) was obtained.
Thereafter, a polyimide having a logarithmic viscosity of 0.65 dl / g and an imidization ratio of 96% was used in the same manner as in Synthesis Example 1 except that the polyamic acid (Aa-3) was used instead of the polyamic acid (Aa-1). 18 g of “polyimide (Ab-4)” was obtained.

[Synthesis Example 5]
The same as Synthesis Example 1 except that 544.5 g (1.0 mol) of the specific acid anhydride IV was used as the tetracarboxylic dianhydride and 198.3 g (1.0 mol) of 4,4′-diaminodiphenylmethane was used as the diamine. As a result, 693 g of polyamic acid (referred to as “polyamic acid (Aa-5)”) was obtained.
Thereafter, a polyimide having a logarithmic viscosity of 0.33 dl / g and an imidization ratio of 82% was obtained in the same manner as in Synthesis Example 1 except that the polyamic acid (Aa-5) was used instead of the polyamic acid (Aa-1). 18 g of “polyimide (Ab-5)” was obtained.

[Synthesis Example 6]
In the same manner as in Synthesis Example 1, except that 598.5 g (1.0 mol) of the specific acid anhydride V was used as the tetracarboxylic dianhydride and 108.1 g (1.0 mol) of p-phenylenediamine was used as the diamine. 661 g of a polyamic acid having a logarithmic viscosity of 0.75 dl / g (referred to as “polyamic acid (Aa-6)”) was obtained.

[Synthesis Example 7]
In the same manner as in Synthesis Example 1, except that 554.5 g (1.0 mol) of the specific acid anhydride VI was used as the tetracarboxylic dianhydride and 108.1 g (1.0 mol) of p-phenylenediamine was used as the diamine, 597 g of a polyamic acid having a logarithmic viscosity of 0.87 dl / g (referred to as “polyamic acid (Aa-7)”) was obtained.

[Synthesis Example 8]
Synthesis Example 1 except that 716.6 g (1.0 mol) of the specific acid anhydride VII was used as the tetracarboxylic dianhydride and 198.3 g (1.0 mol) of 4,4′-diaminodiphenylmethane was used as the diamine. Similarly, 894 g of a polyamic acid having a logarithmic viscosity of 0.88 dl / g (referred to as “polyamic acid (Aa-8)”) was obtained.

[Synthesis Example 9]
The same as Synthesis Example 1 except that 660.6 g (1.0 mol) of the specific acid anhydride VIII was used as the tetracarboxylic dianhydride and 198.3 g (1.0 mol) of 4,4′-diaminodiphenylmethane was used as the diamine. Thus, 832 g of polyamic acid having a logarithmic viscosity of 0.90 dl / g (referred to as “polyamic acid (Aa-9)”) was obtained.

[Synthesis Example 10]
1,3,3a, 4,5,9b-Hexahydro-5 (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] -furan-1,3 as tetracarboxylic dianhydride -A polyamic acid (this is referred to as "polyamic acid (Aa-)" in the same manner as in Synthesis Example 1, except that 300.3 g (1.0 mol) of dione and 584.7 g (1.0 mol) of the specific diamine I were used as the diamine. 10) ") 819 g was obtained.
Thereafter, a polyimide having a logarithmic viscosity of 0.61 dl / g and an imidization ratio of 97% (this was used) except that the polyamic acid (Aa-10) was used instead of the polyamic acid (Aa-1). 18 g of “polyimide (Ab-6)” was obtained.

[Synthesis Example 11]
In the same manner as in Synthesis Example 1, except that 218.1 g (1.0 mol) of pyromellitic dianhydride was used as the tetracarboxylic dianhydride and 584.7 g (1.0 mol) of the specific diamine I was used as the diamine, 769 g of a polyamic acid having a logarithmic viscosity of 0.80 dl / g (referred to as “polyamic acid (Aa-11)”) was obtained.

[Synthesis Example 12]
Except for using 196.1 g (1.0 mol) of 1,2,3,4-cyclobutanetetracarboxylic dianhydride as tetracarboxylic dianhydride and 480.6 g (1.0 mol) of specific diamine II as diamine. In the same manner as in Synthesis Example 1, 603 g of a polyamic acid having a logarithmic viscosity of 0.90 dl / g (referred to as “polyamic acid (Aa-12)”) was obtained.

[Synthesis Example 13]
Synthesis, except that 224.2 g (1.0 mol) of 2,3,5-tricarboxycyclopentylacetic acid dianhydride was used as tetracarboxylic dianhydride and 416.5 g (1.0 mol) of specific diamine III was used as the diamine. In the same manner as in Example 1, 598 g of polyamic acid (referred to as “polyamic acid (Aa-13)”) was obtained.
Thereafter, a polyimide having a logarithmic viscosity of 0.42 dl / g and an imidization ratio of 83% was obtained in the same manner as in Synthesis Example 1 except that the polyamic acid (Aa-13) was used instead of the polyamic acid (Aa-1). 18 g of “polyimide (Ab-7)” was obtained.

[Synthesis Example 14]
196.1 g (1.0 mol) of 1,2,3,4-cyclobutanetetracarboxylic dianhydride was used as the tetracarboxylic dianhydride, and 578.7 g (1.0 mol) of the specific diamine IV was used as the diamine. Except for the above, in the same manner as in Synthesis Example 1, 691 g of polyamic acid having a logarithmic viscosity of 0.91 dl / g (referred to as “polyamic acid (Aa-14)”) was obtained.

[Synthesis Example 15]
1,3,3a, 4,5,9b-hexahydro-5 (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] -furan-1, as tetracarboxylic dianhydride A polyamic having a logarithmic viscosity of 0.55 dl / g in the same manner as in Synthesis Example 1 except that 300.3 g (1.0 mol) of 3-dione and 108.1 g (1.0 mol) of p-phenylenediamine were used as the diamine. 311 g of an acid (referred to as “polyamic acid (Aa-15)”) was obtained.

[Example 1]
(1) Preparation of liquid crystal aligning agent:
4 g of the polyimide (Ab-1) obtained in Synthesis Example 1 was dissolved in a mixed solvent with 96 g of γ-butyrolactone to obtain a solution having a solid content concentration of 4% by weight. This solution was filtered through a filter having a pore diameter of 1 μm to prepare the liquid crystal aligning agent of the present invention.

(2) Production of liquid crystal display element:
1. The liquid crystal aligning agent of the present invention prepared as described above is applied on a transparent conductive film made of an ITO film provided on one surface of a 1 mm thick glass substrate using a spinner and dried at 230 ° C. for 1 hour. By doing so, a coating film having a dry film thickness of 800 mm was formed.
2. The formed coating film surface was rubbed using a rubbing machine having a roll around which a nylon cloth was wound to obtain a liquid crystal alignment film. Here, the rubbing treatment conditions were a roll rotation speed of 400 rpm, a stage moving speed of 3 cm / sec, and a hair foot pushing length of 0.4 mm.
3. Two substrates having a liquid crystal alignment film formed thereon were prepared as described above, and an epoxy resin adhesive containing 5.5 μm diameter aluminum oxide spheres was applied to the outer edge of each substrate by screen printing. Thereafter, the two substrates were placed opposite to each other with a gap so that the rubbing direction in each liquid crystal alignment film was 90 degrees, and the outer edge portions were brought into contact with each other to press the adhesive to cure the adhesive.
4). Nematic liquid crystal “MLC-6221-S010” (manufactured by Merck) is injected and filled in the cell gap defined by the adhesive on the surface and outer edge of the substrate, and then the injection hole is sealed with an epoxy adhesive. Then, a liquid crystal cell was constructed, and it was driven with a rectangular wave of 5 V and 60 Hz for 24 hours. When the presence or absence of display defects was observed with the naked eye, no alignment defect was observed and good liquid crystal alignment was shown. The results are shown in Table 2.

[Examples 2 to 14]
The liquid crystal aligning agent of this invention was prepared like Example 1 using the polyamic acid or polyimide obtained by the synthesis examples 1-14. Next, using the liquid crystal aligning agent thus prepared, the liquid crystal aligning property of the liquid crystal aligning film was evaluated in the same manner as in Example 1. The results are shown in Table 2.

[Comparative Example 1]
A liquid crystal aligning agent for comparison was prepared in the same manner as in Example 1 using the polyimide (Ab-8) obtained in Synthesis Example 15. Next, using the liquid crystal aligning agent thus prepared, the liquid crystal alignment property of the liquid crystal alignment film was evaluated in the same manner as in Example 1. As a result, poor alignment was observed and the liquid crystal alignment property was inferior. It was. The results are shown in Table 2.

Claims (5)

The liquid crystal aligning agent characterized by including the polymer which has at least 1 type chosen from the repeating unit represented by following formula (1)-(4).

(In the formula, Q and R represent different tetravalent organic groups, and X and Y represent different divalent organic groups.) A liquid crystal aligning agent comprising a polymer obtained from a tetracarboxylic dianhydride represented by the following formula (i) and a diamine.

A liquid crystal aligning agent comprising a polymer obtained from a diamine represented by the following formula (ii) and tetracarboxylic dianhydride.

A liquid crystal alignment film obtained from the liquid crystal aligning agent according to claim 1. A liquid crystal display device comprising the liquid crystal alignment film according to claim 4.