JP4524569B2 - Liquid crystal aligning agent and liquid crystal display element - Google Patents

Description

  The present invention relates to a liquid crystal aligning agent and a liquid crystal display element used for forming a liquid crystal alignment film of a liquid crystal display element. More specifically, the present invention relates to a liquid crystal aligning agent and a liquid crystal display element excellent in coatability, which can provide a liquid crystal alignment film that exhibits a high pretilt angle and is excellent in voltage holding ratio.

  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 type liquid crystal display element having a so-called TN type (Twisted Nematic) liquid crystal cell is known.

  Further, STN (Super Twisted Nematic) type liquid crystal display elements have been developed that have higher contrast than TN type liquid crystal display elements and have less viewing angle dependency. 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.

  Also known is a lateral electric field type liquid crystal display element in which two electrodes for driving a liquid crystal are arranged in a comb-like shape on one side of the base, an electric field parallel to the base is generated, and liquid crystal molecules are controlled. 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.

  As a liquid crystal display element different from the above, a liquid crystal display element having a vertical alignment type liquid crystal cell in which liquid crystal molecules having negative dielectric anisotropy are aligned perpendicular to a substrate is known. In such a liquid crystal display element, the alignment control of the liquid crystal is usually performed by a liquid crystal alignment film formed of a liquid crystal alignment agent containing a polymer such as polyamic acid or polyimide.

  Recently, in order to obtain a bright, delicate and beautiful image, a high aperture ratio and a narrowing between pixels have progressed, and accordingly, a substrate having a remarkably large step due to wiring tends to be used for a liquid crystal display element. In the vertical alignment type liquid crystal display element, a so-called MVA type display element is manufactured, and a protrusion made of a photosensitive resin is provided on a substrate, and a liquid crystal alignment film is formed on the protrusion. It is formed.

  The pretilt angle developed by a liquid crystal alignment film formed on a substrate with severe irregularities tends to be lower than that of a liquid crystal alignment film formed on a substrate with few irregularities. For example, in TN type liquid crystal display elements, display defects due to reverse twist There is a known problem that is likely to occur.

  Furthermore, in the MVA type vertical alignment type liquid crystal display device, there is a known problem that display defects are likely to occur near the top of the protrusion due to insufficient vertical alignment, and from this background, a pretilt angle higher than the conventional one is stably expressed. There is a growing demand for liquid crystal alignment films that can be used.

  The liquid crystal alignment film capable of expressing a high pretilt angle is, for example, a long-chain alkyl group such as a hexadecyl group and an octadecyl group disclosed in Patent Document 1, a bicyclohexyl group having an alkyl group disclosed in Patent Document 2, or A polymer in which a bulky aliphatic group or alicyclic group (hereinafter referred to as a pretilt angle-expressing group) such as a steroid group disclosed in Patent Document 3 is used and an amount suitable for a desired pretilt angle is introduced It can form by using the liquid crystal aligning agent manufactured using.

  However, since these pretilt angle-expressing groups are hydrophobic, they have low solubility in highly polar solvents such as γ-butyrolactone and N-methyl-2-pyrrolidone, which are commonly used for liquid crystal aligning agents. For this reason, depending on the target pretilt angle, the solubility of the polyimide having the necessary pretilt angle-expressing group introduced may be significantly reduced. As a result, for example, when an alignment film is formed on a substrate using a printing method, coating unevenness such as cocoon skin unevenness occurs and film thickness uniformity is impaired. There has been a problem that display unevenness is likely to occur due to disturbance.

  For this reason, as disclosed in Patent Document 4, studies have been made to improve coating unevenness by using a polymer having a low imidization rate. However, in particular, liquid crystal display elements for television use use liquid crystal capable of high-speed response in order to display moving images beautifully. For this reason, conventional liquid crystal alignment films have a low voltage holding ratio and display unevenness during long-term lighting. Therefore, there is a problem that a liquid crystal display element having excellent reliability cannot be manufactured.

Therefore, the development of a liquid crystal aligning agent excellent in coating property that can give a liquid crystal aligning film exhibiting a high pretilt angle and excellent in voltage holding ratio has been awaited.
JP-A-6-136122 JP 2003-96034 A Japanese Patent No. 2893671 JP 2002-95499 A

  The present invention has been made in view of the above circumstances, and a first object of the present invention is to provide a coating film that can form a liquid crystal alignment film that exhibits a high pretilt angle and is excellent in voltage holding ratio. It is in providing the liquid crystal aligning agent excellent in the property.

  The second object of the present invention is to provide a liquid crystal aligning agent capable of forming a liquid crystal alignment film having excellent reliability.

  The third object of the present invention is to provide a liquid crystal display device provided with a liquid crystal alignment film from the liquid crystal aligning agent of the present invention.

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

According to the present invention, the above objects and advantages of the present invention, the first, possess both of the repeating unit represented by each of the following formulas (1) and the following formula (2), and of 60% to 95% a liquid crystal aligning agent containing a polymer to have a imidization ratio, the polymer,
2,3,5-tricarboxycyclopentyl acetic acid dianhydride;
1- (2-ethoxyethoxy) -2,4-diaminobenzene, 1- (2- (2-ethoxyethoxy) ethoxy) -2,4-diaminobenzene, 1- (2- (2- (2-ethoxyethoxy) ) Ethoxy) ethoxy) -2,4-diaminobenzene, 1- (2-butoxyethoxy) -2,4-diaminobenzene, 1- (2- (2-butoxyethoxy) ethoxy) -2,4-diaminobenzene, 1- (2- (2- (2-butoxyethoxy) ethoxy) ethoxy) -2,4-diaminobenzene, 1- (4- (2-ethoxyethoxy) cyclohexyloxy) -2,4-diaminobenzene, 1- (4- (2- (2-ethoxyethoxy) ethoxy) cyclohexyloxy) -2,4-diaminobenzene, 1- (4- (2- (2- (2-ethoxyethoxy) eth) C) Ethoxy) cyclohexyloxy) -2,4-diaminobenzene, 1- (4- (2-butoxyethoxy) cyclohexyloxy) -2,4-diaminobenzene, 1- (4- (2- (2-butoxyethoxy) ) Ethoxy) cyclohexyloxy) -2,4-diaminobenzene, 1- (4- (2- (2- (2-butoxyethoxy) ethoxy) ethoxy) cyclohexyloxy) -2,4-diaminobenzene, 1- (4 -(2-ethoxyethoxy) phenoxy) -2,4-diaminobenzene, 1- (4- (2- (2-ethoxyethoxy) ethoxy) phenoxy) -2,4-diaminobenzene, 1- (4- (2 -(2- (2-ethoxyethoxy) ethoxy) ethoxy) phenoxy) -2,4-diaminobenzene, 1- (4- (2-butoxyethoxy) ) Phenoxy) -2,4-diaminobenzene, 1- (4- (2- (2-butoxyethoxy) ethoxy) phenoxy) -2,4-diaminobenzene or 1- (4- (2- (2- (2 -Butoxyethoxy) ethoxy) ethoxy) phenoxy) -2,4-diaminobenzene It is achieved by the liquid crystal aligning agent characterized by being a polymer obtained by reacting with diamine.

Here, P is a tetravalent organic group, Q is a trivalent organic group, X ¹ is an oxygen atom or a sulfur atom, A is an alkylene group, and B is substituted with a halogen atom. And an alkyl group having 1 to 30 carbon atoms and n is an integer of 1 to 5.

  According to the present invention, the above objects and advantages of the present invention are secondly achieved by a liquid crystal display element comprising a liquid crystal alignment film obtained from the liquid crystal aligning agent of the present invention.

  The liquid crystal aligning agent of this invention is excellent in applicability | paintability, expresses a high pretilt angle, and provides the liquid crystal aligning film suitable for liquid crystal display elements which are excellent in a voltage retention.

  Furthermore, a liquid crystal display element having a liquid crystal alignment film formed by using the liquid crystal aligning agent of the present invention is excellent in reliability and can be used effectively in various devices. For example, a desk calculator, a wristwatch, a table clock, a coefficient display board, a mobile phone Used in display devices such as telephones, word processors, personal computers, liquid crystal data projectors, and liquid crystal televisions.

  Hereinafter, the present invention will be described in detail. The polymer that can be used in the present invention is selected from polyamic acid, polyimide, a block polymer having a polyamic acid block and a polyimide block in the molecule, or a mixture of two or more of these polymers. The polyamic acid can be obtained by reacting a tetracarboxylic dianhydride and a diamine compound in an organic solvent. The polyimide can be obtained by dehydrating and ring-closing the synthesized polyamic acid. The block polymer can be obtained, for example, by mixing and aging an amine-terminated polyamic acid and an acid-terminated polyimide as disclosed in JP-A-2000-336168.

The structure represented by each of the above formulas (1) and (2) is represented by —X ¹ — (AX ¹ ) _n —B in the formulas (1) and (2) in at least one of the diamine compounds. By using a compound having a substituent (hereinafter referred to as a specific diamine), it is introduced into the polymer.

  The structure represented by each of the above formulas (1) and (2) has the effect of significantly increasing the solubility of the resulting polymer. For this reason, from the liquid crystal aligning agent manufactured using this polymer, the liquid crystal aligning film which exhibits the outstanding applicability | paintability, expresses a high pretilt angle, and is excellent in the voltage retention rate can be formed.

  The content ratio of the structure represented by the above formula (1) and the structure represented by the above formula (2) in the polymer used in the present invention is preferably 1 to 95 with respect to all repeating units of all the polymers. It is 5 mol%, More preferably, it is 5-80 mol%, More preferably, it is 5-60 mol%.

[Tetracarboxylic dianhydride]
The tetracarboxylic acid anhydride that can be used in the present invention is represented by the following formula (3).

Here, the definition of P is the same as the above formula (1).
It is represented by Such tetracarboxylic acid dianhydride, for example, 2, can be mentioned 3,5-tricarboxy cyclopentyl acetic dianhydride.

[Diamine compound]
The diamine compound used in the present invention has the following formula (9):

Here, the definitions of Q, X ¹ , A, B and n are the same as in the above formula (1).
It is represented by A representing an alkylene group is preferably an alkylene group having 2 to 10 carbon atoms .

Examples of such diamine compounds (hereinafter sometimes referred to as “specific diamine compounds”) include 1- (2-ethoxyethoxy) -2,4-diaminobenzene, 1- (2- (2-ethoxyethoxy) ethoxy) -2, 4-diaminobenzene, 1- (2- (2- (2-ethoxyethoxy) ethoxy) ethoxy) -2,4-diaminobenzene, 1- (2-butoxyethoxy) -2,4-diaminobenzene, 1- ( 2- (2-butoxyethoxy) ethoxy) -2,4-diaminobenzene, 1- (2- (2- (2-butoxyethoxy) ethoxy) ethoxy) -2,4-diaminobenzene, 1- (4- ( 2-ethoxyethoxy) cyclohexyloxy) -2,4-diaminobenzene, 1- (4- (2- (2-ethoxyethoxy) ethoxy) cyclohexyloxy)- 2,4-diaminobenzene, 1- (4- (2- (2- (2-ethoxyethoxy) ethoxy) ethoxy) cyclohexyloxy) -2,4-diaminobenzene, 1- (4- (2-butoxyethoxy) Cyclohexyloxy) -2,4-diaminobenzene, 1- (4- (2- (2-butoxyethoxy) ethoxy) cyclohexyloxy) -2,4-diaminobenzene, 1- (4- (2- (2- (2- ( 2-butoxyethoxy) ethoxy) ethoxy) cyclohexyloxy) -2,4-diaminobenzene, 1- (4- (2-ethoxyethoxy) phenoxy) -2,4-diaminobenzene, 1- (4- (2- ( 2-ethoxyethoxy) ethoxy) phenoxy) -2,4-diaminobenzene, 1- (4- (2- (2- (2-ethoxyethoxy) ethoxy) eth) Ii) phenoxy) -2,4-diaminobenzene, 1- (4- (2-butoxyethoxy) phenoxy) -2,4-diaminobenzene, 1- (4- (2- (2-butoxyethoxy) ethoxy) phenoxy ) -2,4-diaminobenzene, 1- (4- (2- (2- (2-butoxyethoxy) ethoxy) ethoxy) phenoxy) -2,4-diaminobenzene .

  In this invention, if it is a range which does not impair the effect of this invention, other diamine compounds other than the said specific diamine can also be used. Examples of other diamine compounds used for the synthesis of the polyamic acid include p-phenylenediamine, m-phenylenediamine, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylethane, and 4,4′-diaminodiphenyl. Sulfide, 4,4′-diaminodiphenyl sulfone, 3,3′-dimethyl-4,4′-diaminobiphenyl, 4,4′-diaminobenzanilide, 4,4′-diaminodiphenyl ether, 1,5-diaminonaphthalene, 2,2′-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′-di Minobenzophenone, 3,4'-diaminobenzophenone, 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, 4,4'-bis [(4-amino-2- Aromatic diamines such as (trifluoromethyl) phenoxy] -octafluorobiphenyl;

1,1 m-xylylenediamine, 1,3-propanediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, heptamethylene diamine, octamethylene diamine, nonamethylene diamine, 1, 4-diaminocyclohexane, isophorone diamine, Tetrahydrodicyclopentadienylenediamine, hexahydro-4,7-methanoindanylene methylenediamine, tricyclo [6.2.1.0 ^2,7 ] -undecylenedimethyldiamine, 4,4'-methylenebis (cyclohexylamine) Aliphatic and cycloaliphatic diamines such as;

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 2 in the molecule such as phenylphenanthridine, 1,4-diaminopiperazine, 3,6-diaminoacridine, bis (4-aminophenyl) phenylamine and compounds represented by the following formulas (10) to (13) A diamine having one primary amino group and a nitrogen atom other than the primary amino group;

(In the formula, R ⁵ represents a monovalent organic group having a ring structure containing a nitrogen atom selected from the group consisting of 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 R ⁶ may be the same or different.)

  Mono-substituted phenylenediamines represented by the following formula (12); diaminoorganosiloxanes represented by the following formula (13);

(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, R ⁹ there are a plurality each may be the same or different, p is an integer of 1 to 3, q is from 1 to 20 Is an integer.)

  Examples include compounds represented by the following formulas (14) to (18). These diamine compounds can be used alone or in combination of two or more.

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

  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 Aminophenoxy) benzene, 4,4′-bis (4-aminophenoxy) biphenyl, compounds represented by the above formulas (14) to (18), 2,6-diaminopyridine, 3,4-diaminopyridine, 2, 4-diaminopyrimidine, 3,6-diaminoacridine, a compound represented by the following formula (19) among the compounds represented by the above formula (10), and a compound represented by the following formula (11) Of the compound represented by 20) and the compound represented by the above formula (12), compounds represented by the following formulas (21) to (26) are preferred. These other diamine compounds are preferably used in an amount of 20 to 95 mol%, more preferably 40 to 95 mol%, based on the total diamine compounds.

[Synthesis of polyamic acid]
The ratio of tetracarboxylic dianhydride and diamine used in 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, dimethyl sulfoxide And aprotic polar solvents such as γ-butyrolactone, tetramethylurea and hexamethylphosphortriamide; and phenolic solvents such as m-cresol, xylenol, phenol and halogenated phenol. The amount of organic solvent used (α) is such that the total amount (β) of tetracarboxylic dianhydride and diamine compound is 0.1 to 30% by weight with respect to the total amount (α + β) of the reaction solution. It is preferable that

  In addition, in the organic solvent, alcohols, ketones, esters, ethers, halogenated hydrocarbons, hydrocarbons, and the like, which are poor solvents for polyamic acid, are used in combination as long as the generated polyamic acid does not precipitate. be able to. 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.

[Synthesis of imidized polymer]
The imidized polymer constituting the liquid crystal aligning agent of the present invention can be synthesized by dehydrating and ring-closing the polyamic acid. 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. Although the usage-amount of a dehydrating agent is based on the desired imidation rate, it is preferable to set it as 0.01-20 mol with respect to 1 mol of repeating units of a polyamic acid. 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-closing catalyst used is preferably 0.01 to 10 mol with respect to 1 mol of the dehydrating agent used. The imidization rate can be increased as the amount of the above dehydrating agent and dehydrating ring-closing agent is increased. Imidization is viewpoint et 6 0% to 95% of the voltage holding ratio of the liquid crystal display device. Examples of the organic solvent used in the dehydration ring closure reaction include the same organic solvents as exemplified for use in the synthesis of polyamic acid. The reaction temperature of the dehydration ring closure reaction is preferably 0 to 180 ° C, more preferably 10 to 150 ° C. In addition, the imidized polymer can be purified by performing the same operation as in the polyamic acid purification method on the reaction solution thus obtained.

[End-modified polymer]
The polyamic acid and imidized polymer used in the present invention may be of 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 a dicarboxylic acid monoanhydride, a monoamine compound, a monoisocyanate compound or the like to the reaction system when synthesizing a polyamic acid. Here, as the dicarboxylic acid monoanhydride, for example, maleic anhydride, phthalic anhydride, itaconic anhydride, n-decylsuccinic anhydride, n-dodecylsuccinic anhydride, n-tetradecylsuccinic anhydride And n-hexadecyl succinic anhydride. Examples of the monoamine compound include aniline, cyclohexylamine, n-butylamine, n-pentylamine, n-hexylamine, n-heptylamine, n-octylamine, n-nonylamine, n-decylamine, n-undecylamine, n -Dodecylamine, n-tridecylamine, n-tetradecylamine, n-pentadecylamine, n-hexadecylamine, n-heptadecylamine, n-octadecylamine, n-eicosylamine . Examples of the monoisocyanate compound include phenyl isocyanate and naphthyl isocyanate.

[Logarithmic viscosity of polymer]
The polyamic acid and imidized polymer obtained as described above preferably have a logarithmic viscosity (η _ln ) of 0.05 to 10 dl / g, more preferably 0.05 to 5 dl / g.

The value of 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 and containing the polyamic acid and / or imidized polymer 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 (or butyl cellosolve), ethylene glycol dimethyl ether, ethylene glycol ethyl ether acetate, diethylene glycol di Examples include methyl ether, diethylene glycol diethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether acetate, and diethylene glycol monoethyl ether acetate.

  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 film thickness of this coating film is too small. It is difficult to obtain a good liquid crystal alignment film, and when the solid content concentration exceeds 10% by weight, it is easy to obtain a good liquid crystal alignment film because the film thickness is excessive. In addition, the viscosity of the liquid crystal aligning agent increases and the coating properties tend to be inferior.

  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. Diol diglycidyl ether, glycerin diglycidyl ether, 2,2-dibromoneopentyl glycol diglycidyl ether, 1,3,5,6-tetraglycidyl-2,4-hexanediol, N, N, N ′, N ′, Tetraglycidyl-m-xylenediamine, 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, N, N, N ′, N ′,-tetraglycidyl-4, '- diaminodiphenylmethane, 3- (N-Ariru N Gurishijiru) aminopropyltrimethoxysilane, 3- (N, N-diglycidyl) and aminopropyl trimethoxy silane can be cited.

[Liquid crystal display element]
The liquid crystal display element of the present invention can be produced, for example, by the following method.
(1) A protrusion is formed on one surface of a substrate provided with a patterned transparent conductive film using a photosensitive resin, and the liquid crystal aligning agent of the present invention is applied by a method such as a roll coater method, a spinner method, or a printing method. Coating is performed, and then the coating surface is heated to form a coating film. Here, as the substrate, for example, a glass such as float glass or soda glass; a transparent substrate made of a plastic such as polyethylene terephthalate, polybutylene terephthalate, polyethersulfone, 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 preferably 80 to 300 ° C, more preferably 120 to 250 ° C. 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. It can also be a membrane. The film thickness of the formed coating film is preferably 0.001-1 μm, more preferably 0.005-0.5 μm.

(2) A substrate on which the liquid crystal alignment film is formed as described above and a substrate on which the transparent conductive film is not patterned are produced one by one, and the two substrates are interposed via a gap (cell gap). A liquid crystal cell is constructed by arranging the two substrates so that the peripheral parts of the two substrates are bonded together using a sealant, and the liquid crystal is injected and filled in the cell gap defined by the substrate surface and the sealant, and the injection hole is sealed. To do. 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 substrate which comprises a liquid crystal cell, so that the polarization direction may mutually orthogonally cross.

  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. Liquid crystal, biphenylcyclohexane liquid crystal, pyrimidine liquid crystal, dioxane liquid crystal, bicyclooctane liquid crystal, cubane 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.

  In addition, as a polarizing plate 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 is stretched and oriented while sandwiching polyvinyl alcohol with a cellulose acetate protective film. 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 evaluation method in each liquid crystal display element produced by the following examples and comparative examples is shown below.

[Imidation rate of polymer / Average imidation rate of liquid crystal aligning agent]
A polymer or a liquid crystal aligning agent is dried at room temperature under reduced pressure and then dissolved in deuterated dimethyl sulfoxide, and ¹ H-NMR is measured at room temperature using tetramethylsilane as a reference substance, and determined by the formula shown by the following formula (ii). It was.

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)

[Printability test of imidized polymer / liquid crystal aligning agent]
A polymer or a liquid crystal aligning agent is dissolved in a mixed solvent of γ-butyrolactone / N-methylpyrrolidone / butyl cellosolve (70/10/20 (weight ratio)) to obtain a solution having a solid content concentration of 4% by weight. It filtered using the filter and the liquid crystal aligning agent of this invention was prepared. The liquid crystal aligning agent is applied to the transparent electrode surface of a glass substrate with a transparent electrode made of an ITO film using a liquid crystal alignment film printer (Nissha Printing Co., Ltd.), and then on a hot plate at 80 ° C. for 1 minute. After drying, the film was dried on a hot plate at 180 ° C. for 20 minutes to form a film having an average film thickness of 600 Å. This substrate was observed with a microscope with a magnification of 20 times, and the quality of the printability was determined by the presence or absence of printing unevenness and pinholes.

[Pretilt angle of liquid crystal display element]
In accordance with the method described in “TJ Scheffer, et.al., J. Appl.Phys., Vol.19, 2013 (1980)”, the measurement was performed by a crystal rotation method using He—Ne laser light.

[Voltage holding ratio of liquid crystal display element]
A voltage of 5 V was applied to the liquid crystal display element at a temperature of 60 ° C. with an application time of 60 microseconds and a span of 167 milliseconds, and then the voltage holding ratio after 167 milliseconds from release of application was measured. The measuring apparatus used was VHR-1 manufactured by Toyo Corporation.

[Reliability test of liquid crystal display elements]
In a high-temperature and high-humidity environment (temperature: 70 ° C., relative humidity: 80%), the liquid crystal display element was driven with a rectangular wave of 5 V and 60 Hz, and the presence or absence of display defects after 1500 hours was observed with a polarizing microscope.

Synthetic Examples and Comparative Synthetic Examples To N-methyl-2-pyrrolidone, the composition shown in Table 1 was added in the order of diamine and tetracarboxylic dianhydride (shown as “acid anhydride” in the table) in this order. A 15% by weight solution was made to react at 60 ° C. for 6 hours to obtain a polyamic acid solution. For the polymers PA-1 and PA-2, the obtained polyamic acid solution was reprecipitated with diethyl ether, and then collected and dried to obtain polyamic acids having logarithmic viscosity shown in Table 1.
About polymer PI-1-10, after adding 2 times mole of pyridine and 2 times mole of acetic anhydride with respect to the tetracarboxylic dianhydride used to the obtained polyamic acid solution, it heated at 110 degreeC. For 4 hours. The obtained polyimide solution was reprecipitated with diethyl ether, then recovered and dried to obtain polyimides having logarithmic viscosities and imidization ratios shown in Table 1.

The diamine compounds and tetracarboxylic dianhydrides in Table 1 are as follows.
<Diamine compound>
A-1: 1- (2-Ethoxyethoxy) -2,4-diaminobenzene A-2: 1- (2- (2- (2-ethoxyethoxy) ethoxy) ethoxy) -2,4-diaminobenzene A- 3: 1- (2-Butoxyethoxy) -2,4-diaminobenzene

B-1: p-phenylenediamine B-2: diamine represented by the above formula (21) B-3: 1-n-octadecyloxy-2,4-diaminobenzene B-4: 4- (4-n -Heptylcyclohexyl) phenoxy-2,4-diaminobenzene B-5: 2,2'-dimethyl-4,4'-diaminobiphenyl

<Tetracarboxylic dianhydride>
T-1: 2,3,5-tricarboxycyclopentyl-1-acetic acid dianhydride T-2: 3,5,6-tricarboxynorbornyl-2-acetic acid dianhydride T-3: 1,2, 3,4-cyclobutanetetracarboxylic dianhydride

Example 1
2 g of the imidized polymer (PI-1) obtained in Synthesis Example 1 was dissolved in γ-butyrolactone to obtain a solution having a solid content concentration of 6% by weight, and this solution was filtered with a filter having a pore size of 1 μm. A liquid crystal aligning agent was prepared.

  As shown in FIG. 1, the 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. Then, by drying at 80 ° C. for 1 minute and then at 200 ° C. for 1 hour, a coating film having a dry film thickness of 600 Å was formed, and the coating property was evaluated. A case with coating unevenness was judged as bad and a case without coating was judged as good.

  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.

  Next, after filling and filling a negative type liquid crystal MLC6608 manufactured by Merck between a pair of substrates from the liquid crystal injection port, the liquid crystal injection holes are sealed with an epoxy adhesive, and polarizing plates are provided on both sides of the substrate. The vertically aligned liquid crystal display element of the present invention was produced by pasting together so that the polarization directions of the two were perpendicular to each other.

  The pre-tilt angle, voltage holding ratio, and reliability of the obtained liquid crystal display element were evaluated. The evaluation results are shown in Table 2 together with the applicability test results.

Examples 2-7, Comparative Examples 1-5
A liquid crystal aligning agent was prepared in the same manner as in Example 1 except that the polymer shown in Table 1 was used, and a liquid crystal display device was produced using this, and evaluated. The evaluation results are shown in Table 2.

Explanatory drawing which shows the section of a liquid crystal display element

Explanation of symbols

1, 3 Glass plate 2 ITO film 4 Protrusion 5 Recess 6 Liquid crystal

Claims (3)

Possess both of the repeating unit represented by each of the following formulas (1) and the following formula (2), a liquid crystal aligning agent and containing a polymer which have a fraction of imide units of 60% to 95%, wherein The polymer is
2,3,5-tricarboxycyclopentyl acetic acid dianhydride;
1- (2-ethoxyethoxy) -2,4-diaminobenzene, 1- (2- (2-ethoxyethoxy) ethoxy) -2,4-diaminobenzene, 1- (2- (2- (2-ethoxyethoxy) ) Ethoxy) ethoxy) -2,4-diaminobenzene, 1- (2-butoxyethoxy) -2,4-diaminobenzene, 1- (2- (2-butoxyethoxy) ethoxy) -2,4-diaminobenzene, 1- (2- (2- (2-butoxyethoxy) ethoxy) ethoxy) -2,4-diaminobenzene, 1- (4- (2-ethoxyethoxy) cyclohexyloxy) -2,4-diaminobenzene, 1- (4- (2- (2-ethoxyethoxy) ethoxy) cyclohexyloxy) -2,4-diaminobenzene, 1- (4- (2- (2- (2-ethoxyethoxy) eth) C) Ethoxy) cyclohexyloxy) -2,4-diaminobenzene, 1- (4- (2-butoxyethoxy) cyclohexyloxy) -2,4-diaminobenzene, 1- (4- (2- (2-butoxyethoxy) ) Ethoxy) cyclohexyloxy) -2,4-diaminobenzene, 1- (4- (2- (2- (2-butoxyethoxy) ethoxy) ethoxy) cyclohexyloxy) -2,4-diaminobenzene, 1- (4 -(2-ethoxyethoxy) phenoxy) -2,4-diaminobenzene, 1- (4- (2- (2-ethoxyethoxy) ethoxy) phenoxy) -2,4-diaminobenzene, 1- (4- (2 -(2- (2-ethoxyethoxy) ethoxy) ethoxy) phenoxy) -2,4-diaminobenzene, 1- (4- (2-butoxyethoxy) ) Phenoxy) -2,4-diaminobenzene, 1- (4- (2- (2-butoxyethoxy) ethoxy) phenoxy) -2,4-diaminobenzene or 1- (4- (2- (2- (2 The liquid crystal aligning agent is a polymer obtained by reacting a diamine containing butoxyethoxy) ethoxy) ethoxy) phenoxy) -2,4-diaminobenzene.

Here, P is a tetravalent organic group, Q is a trivalent organic group, X ¹ is an oxygen atom or a sulfur atom, A is an alkylene group, and B is substituted with a halogen atom. And an alkyl group having 1 to 30 carbon atoms and n is an integer of 1 to 5. The liquid crystal aligning agent of Claim 1 in which the said diamine further contains the compound represented by following formula (21).

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

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