JP5929565B2 - Liquid crystal alignment agent, liquid crystal alignment film, and liquid crystal display element - Google Patents

Description

  The present invention relates to a liquid crystal aligning agent, a liquid crystal aligning film, and a liquid crystal display element. The liquid crystal alignment film and the liquid crystal display element are manufactured.

  Conventionally, as a liquid crystal display element, a horizontal alignment type such as a TN mode, an IPS mode, and an FFS mode and a vertical alignment type such as a VA mode are known. These liquid crystal display elements have a liquid crystal alignment film for aligning liquid crystal molecules. As a material for the liquid crystal alignment film, polyamic acid or polyimide is generally used from the viewpoints of various properties such as heat resistance, mechanical strength, and affinity with liquid crystal.

  In recent years, liquid crystal display elements are used not only for display terminals such as personal computers as in the past, but also for various applications such as display units for liquid crystal televisions, car navigation systems, mobile phones, smartphones, and the like. Yes. On the other hand, depending on the application of the liquid crystal display element, the liquid crystal display element may be used under conditions that are severer than conventional ones in terms of luminance and driving time. Against this background, liquid crystal display elements have recently been required to have high display quality and little deterioration in display quality even when continuous driving is performed for a long time. Various liquid crystal aligning agents for obtaining a liquid crystal display element have been proposed (see, for example, Patent Document 1 and Patent Document 2).

JP 2010-97188 A JP 2010-156934 A

  In order to improve the display quality of the liquid crystal display element, for example, by increasing the imidation ratio of polyimide in the liquid crystal alignment film to improve electrical characteristics, or by introducing a liquid crystal alignment component (pretilt component) into the polyimide, It may be possible to improve the orientation. However, when these are performed, the solubility of the polymer is likely to decrease or the cohesiveness of the polymer is likely to increase, and as a result, printing unevenness may occur when the liquid crystal aligning agent is applied on the substrate. In some cases, printability may be deteriorated, for example, polyimide may be deposited while printing is performed for a long time.

  The present invention has been made in view of the above problems, and has as its main object to provide a liquid crystal aligning agent excellent in printability, and a liquid crystal alignment film and a liquid crystal display element produced using the liquid crystal aligning agent.

  As a result of intensive studies to achieve the above-described problems of the prior art, the present inventors have used a polymer obtained by the reaction of a specific diamine and tetracarboxylic dianhydride as a polymer component of a liquid crystal aligning agent. It was found that the above problem can be solved by preparing a liquid crystal aligning agent by dissolving the polymer in a specific solvent while using the present invention, and completed the present invention. Specifically, the present invention provides the following liquid crystal aligning agent, liquid crystal alignment film, and liquid crystal display element.

（式（１）中、Ｒ^１及びＲ^２は、それぞれ独立に、水素原子、炭素数１〜６の炭化水素基、又は当該炭化水素基の炭素−炭素結合間に−Ｏ−を含む１価の基であり、Ｒ^１とＲ^２とが互いに結合して環構造を形成してもよい。Ｒ^３は、炭素数１〜６のアルキル基である。） According to the present invention, A) tetracarboxylic dianhydride and 1- (4-aminophenyl) -2,3-dihydro-1,3,3-trimethyl-1H-indene-5-amine and 1- ( 4-aminophenyl) -2,3-dihydro-1,3,3-trimethyl-1H-indene-6-amine and a diamine containing at least one (hereinafter also referred to as a specific diamine). And at least one polymer (A) selected from the group consisting of a polyimide obtained by dehydrating and ring-closing the polyamic acid, and B) 1,3-dimethyl-2-imidazolidinone, N-ethyl There is provided a liquid crystal aligning agent containing 2-pyrrolidone and at least one solvent (B) selected from the group consisting of compounds represented by the following formula (1).

(In formula (1), R ¹ and R ² each independently represent a hydrogen atom, a hydrocarbon group having 1 to 6 carbon atoms, or a monovalent group including —O— between the carbon-carbon bonds of the hydrocarbon group. R ¹ and R ² may be bonded to each other to form a ring structure, and R ³ is an alkyl group having 1 to 6 carbon atoms.)

  The liquid crystal aligning agent of the present invention includes the polymer (A) as a polymer component and the solvent (B) as a solvent, so that the coating property to the substrate is good and the printing on the substrate is long. Even when the test is carried out for a long time, the polymer is hardly precipitated and is excellent in printability for a long time.

  In the present invention, in order to further suppress the precipitation of the polymer, the content of the solvent (B) is preferably 10% by weight or more based on the entire solvent. Thereby, the applicability | paintability to a board | substrate and long-time printability can be made more favorable. In addition, examples of the tetracarboxylic dianhydride in the polymer (A) include 2,3,5-tricarboxycyclopentylacetic acid dianhydride and 2,4,6,8-tetracarboxybicyclo [3.3.0]. A compound containing at least one of octane-2: 4, 6: 8-dianhydride is preferably used.

  The liquid crystal aligning agent of the present invention preferably further contains dipropylene glycol monomethyl ether as a solvent in addition to the solvent (B). By using the solvent (B) and dipropylene glycol monomethyl ether in combination, long-term printability can be further improved.

  Furthermore, according to the present invention, a liquid crystal alignment film formed of the liquid crystal alignment agent described above and a liquid crystal display device including the liquid crystal alignment film are provided. Since the liquid crystal alignment film of the present invention is formed using the liquid crystal aligning agent described above, even when printing is performed for a long time, it is difficult for the polymer to precipitate and the film quality is good. Moreover, when manufacturing a liquid crystal display element using such a liquid crystal aligning film, a printing defect can be reduced in a manufacturing process, As a result, a yield can be improved.

  The liquid crystal aligning agent of the present invention contains at least one polymer selected from the group consisting of a polyamic acid obtained by reacting a tetracarboxylic dianhydride and a diamine and a polyimide formed by dehydrating and ring-closing the polyamic acid. The polymer is dissolved in a solvent. Hereinafter, the liquid crystal aligning agent of this invention is demonstrated in detail.

<Polyamic acid>
[Tetracarboxylic dianhydride]
Examples of the tetracarboxylic dianhydride used for synthesizing the polyamic acid in the present invention include aliphatic tetracarboxylic dianhydride, alicyclic tetracarboxylic dianhydride, aromatic tetracarboxylic dianhydride and the like. Can be mentioned. Specific examples of these are:
Examples of the aliphatic tetracarboxylic dianhydride include 1,2,3,4-butanetetracarboxylic dianhydride;
Examples of the alicyclic tetracarboxylic dianhydride include 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentylacetic acid dianhydride, 1,3,3a, 4, 5,9b-Hexahydro-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] furan-1,3-dione, 1,3,3a, 4,5,9b- Hexahydro-8-methyl-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] furan-1,3-dione, 3-oxabicyclo [3.2.1] octane -2,4-dione-6-spiro-3 '-(tetrahydrofuran-2', 5'-dione), 5- (2,5-dioxotetrahydro-3-furanyl) -3-methyl-3-cyclohexene- No 1,2-dicarboxylic acid 3,5,6-tricarboxy-2-carboxymethylnorbornane-2: 3,5: 6-dianhydride, 2,4,6,8-tetracarboxybicyclo [3.3.0] octane-2 : 4,6: 8-dianhydride, 4,9-dioxatricyclo [5.3.1.0 ^2,6 ] undecane-3,5,8,10-tetraone, cyclohexanetetracarboxylic dianhydride Etc .;
Examples of the aromatic tetracarboxylic dianhydride include pyromellitic dianhydride; and the like, and tetracarboxylic dianhydrides described in JP 2010-97188 A can be used. In addition, the said tetracarboxylic dianhydride can be used individually by 1 type or in combination of 2 or more types.

  Among these, the tetracarboxylic dianhydride used for synthesizing the polyamic acid preferably includes an alicyclic tetracarboxylic dianhydride from the viewpoints of transparency and solubility in a solvent, Among them, 2,3,5-tricarboxycyclopentyl acetic 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, 2,4,6,8-tetracarboxybicyclo [3.3.0] octane-2: 4,6: 8-dianhydride and 1,2,3 4-cyclobutanetetracar It is preferable that at least one selected from the group consisting of acid dianhydrides is included, and particularly in terms of good printability, 2,3,5-tricarboxycyclopentylacetic acid dianhydride and 2,4,4 It is preferable that it contains at least one of 6,8-tetracarboxybicyclo [3.3.0] octane-2: 4,6: 8-dianhydride.

  As the tetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentylacetic acid dianhydride and 2,4,6,8-tetracarboxybicyclo [3.3.0] octane-2: 4,6: 8 -When including at least one of dianhydrides, the total content of these compounds is preferably 10 mol% or more based on the total amount of tetracarboxylic dianhydrides used for the synthesis of polyamic acid, More preferably, it is 20-100 mol%.

[Diamine]
Examples of the diamine used for synthesizing the polyamic acid in the present invention include 1- (4-aminophenyl) -2,3-dihydro-1,3,3-trimethyl-1H-indene-5-amine and 1- ( 4-aminophenyl) -2,3-dihydro-1,3,3-trimethyl-1H-indene-6-amine is included (specific diamine). By using such a specific diamine, the solubility of the polymer component (polyamic acid or polyimide) contained in the liquid crystal aligning agent in the solvent can be enhanced. In particular, the solubility with respect to the solvent containing the solvent (B) shown below is favorable, and the printability can be suitably improved by combining with the solvent.

  The ratio of the specific diamine is preferably 5 mol% or more, more preferably 10 to 80 mol%, still more preferably 10 to 50 mol%, based on the total amount of diamine used for the synthesis of the polyamic acid.

  As the diamine for synthesizing the polyamic acid, the above specific diamine may be used alone, but other diamines may be used in combination with the above specific diamine.

Examples of other diamines that can be used here include aliphatic diamines, alicyclic diamines, aromatic diamines, and diaminoorganosiloxanes. Specific examples thereof include aliphatic diamines such as 1,1-metaxylylenediamine, 1,3-propanediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine and the like;
Examples of alicyclic diamines include 1,4-diaminocyclohexane, 4,4′-methylenebis (cyclohexylamine), 1,3-bis (aminomethyl) cyclohexane and the like;

（式中、Ｘ^I及びＸ^IIは、それぞれ、単結合、−Ｏ−、−ＣＯＯ−又は−ＯＣＯ−であり、Ｒ^Ｉは、炭素数１〜３のアルカンジイル基であり、ａは０又は１であり、ｂは０〜２の整数であり、ｃは１〜２０の整数であり、ｎは０又は１である。但し、ａ及びｂが同時に０になることはない。）
で表される化合物などを； Examples of aromatic diamines include p-phenylenediamine, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenyl sulfide, 1,5-diaminonaphthalene, 2,2′-dimethyl-4,4′-diaminobiphenyl, 2,2′-bis (trifluoromethyl) -4,4′-diaminobiphenyl, 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-phenylenediisopropylene Riden) bisaniline, 1,4-bis (4-aminophenoxy) benzene, 4,4′-bis (4-aminophenoxy) biphenyl, 2,6-diaminopyridine, 3,4-diaminopyridine, 2,4-diamino Pyrimidine, 3,6-diaminoacridine, 3,6-diaminocarbazole, N-methyl-3,6-diaminocarbazole, N-ethyl-3,6-diaminocarbazole, N-phenyl-3,6-diaminocarbazole, N , N′-bis (4-aminophenyl) -benzidine, N, N′-bis (4-aminophenyl) -N, N′-dimethylbenzidine, 1,4-bis- (4-aminophenyl) -piperazine, 3,5-diaminobenzoic acid, cholestanyloxy-3,5-diaminobenzene, cholestenyloxy-3,5-diaminobenzene, Lestanyloxy-2,4-diaminobenzene, cholestenyloxy-2,4-diaminobenzene, cholestanyl 3,5-diaminobenzoate, cholestenyl 3,5-diaminobenzoate, lanostannyl 3,5-diaminobenzoate, 3 , 6-bis (4-aminobenzoyloxy) cholestane, 3,6-bis (4-aminophenoxy) cholestane, 4- (4′-trifluoromethoxybenzoyloxy) cyclohexyl-3,5-diaminobenzoate, 4- (4′-trifluoromethylbenzoyloxy) cyclohexyl-3,5-diaminobenzoate, 1,1-bis (4-((aminophenyl) methyl) phenyl) -4-butylcyclohexane, 1,1-bis (4 -((Aminophenyl) methyl) phenyl) -4-heptylcyclohexane, 1,1 -Bis (4-((aminophenoxy) methyl) phenyl) -4-heptylcyclohexane, 1,1-bis (4-((aminophenyl) methyl) phenyl) -4- (4-heptylcyclohexyl) cyclohexane, 2, 4-diamino-N, N-diallylaniline, 4-aminobenzylamine, 3-aminobenzylamine, and the following formula (A-1)

Wherein X ^I and X ^II are each a single bond, —O—, —COO— or —OCO—, R ^I is an alkanediyl group having 1 to 3 carbon atoms, and a is 0 or And b is an integer of 0 to 2, c is an integer of 1 to 20, and n is 0 or 1. However, a and b are not 0 at the same time.)
A compound represented by:

  Examples of the diaminoorganosiloxane include 1,3-bis (3-aminopropyl) -tetramethyldisiloxane, and the like, and diamines described in JP 2010-97188 A can be used.

Examples of the divalent group represented by “—X ^I — (R ^I —X ^II ) _n —” in the formula (A-1) include alkanediyl groups having 1 to 3 carbon atoms, * —O—, * —COO— or * —O—C ₂ H ₄ —O— (however, a bond marked with “*” is bonded to a diaminophenyl group) is preferred. Specific examples of the group “—C _c H _{2c + 1} ” include, for example, methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group. Group, n-nonyl group, n-decyl group, n-dodecyl group, n-tridecyl group, n-tetradecyl group, n-pentadecyl group, n-hexadecyl group, n-heptadecyl group, n-octadecyl group, n-nonadecyl group Group, n-eicosyl group and the like. The two amino groups in the diaminophenyl group are preferably in the 2,4-position or the 3,5-position with respect to the group “X ^I ”.

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

Moreover, when synthesizing a polyamic acid contained in a liquid crystal aligning agent for a vertical alignment type, a pretilt component may be included as the other diamine in order to give good vertical alignment. Specific examples of the diamine for containing such a pretilt component include dodecanoxy-2,4-diaminobenzene, tetradecanoxy-2,4-diaminobenzene, pentadecanoxy-2,4-diaminobenzene, hexadecanoxy-2,4. -Diaminobenzene, octadecanoxy-2,4-diaminobenzene, dodecanoxy-2,5-diaminobenzene, tetradecanoxy-2,5-diaminobenzene, pentadecanoxy-2,5-diaminobenzene, hexadecanoxy-2,5-diaminobenzene, octadecanoxy -2,5-diaminobenzene, cholestanyloxy-3,5-diaminobenzene, cholestenyloxy-3,5-diaminobenzene, cholestenyloxy-2,4-diaminobenzene, 3,5-diaminobenzoic acid Cholestanyl, cholestenyl 3,5-diaminobenzoate, lanostannyl 3,5-diaminobenzoate, 3,6-bis (4-aminobenzoyloxy) cholestane, 3,6-bis (4-aminophenoxy) cholestane, 4- ( 4'-trifluoromethoxybenzoyloxy) cyclohexyl-3,5-diaminobenzoate, 4- (4'-trifluoromethylbenzoyloxy) cyclohexyl-3,5-diaminobenzoate, 1,1-bis (4- ( (Aminophenyl) methyl) phenyl) -4-butylcyclohexane, 1,1-bis (4-((aminophenyl) methyl) phenyl) -4-heptylcyclohexane, 1,1-bis (4-((aminophenoxy)) Methyl) phenyl) -4-heptylcyclohexane, 1,1-bis (4-((aminophen Nyl) methyl) phenyl) -4- (4-heptylcyclohexyl) cyclohexane, diamines represented by the above formula (A-1), and the like. In addition, the other diamine as a pretilt component can be used individually by 1 type or in combination of 2 or more types.
The total amount of other diamines as the pretilt component is preferably 5 mol% or more, more preferably 10 mol% or more, based on the total diamine.

  The diamine used when synthesizing the polyamic acid in the present invention preferably contains an aromatic diamine (a diamine having an amino group bonded to an aromatic ring) in an amount of 30 mol% or more based on the total diamine, and 50 mol. %, More preferably 80% by mole or more.

[Molecular weight regulator]
When synthesizing a polyamic acid, a terminal-modified polymer may be synthesized using an appropriate molecular weight regulator together with the tetracarboxylic dianhydride and diamine as described above. By using such a terminal-modified polymer, the coating property (printability) of the liquid crystal aligning agent can be further improved without impairing the effects of the present invention.

Examples of molecular weight regulators include acid monoanhydrides, monoamine compounds, and monoisocyanate compounds. Specific examples of these acid monoanhydrides include maleic anhydride, phthalic anhydride, itaconic anhydride, n-decylsuccinic anhydride, n-dodecylsuccinic anhydride, n-tetradecylsuccinic acid. Nic acid anhydride, n-hexadecyl succinic acid anhydride, etc .;
Examples of monoamine compounds include aniline, cyclohexylamine, n-butylamine, n-pentylamine, n-hexylamine, n-heptylamine, and n-octylamine;
Examples of the monoisocyanate compound include phenyl isocyanate and naphthyl isocyanate.

  The use ratio of the molecular weight regulator is preferably 20 parts by weight or less, and more preferably 10 parts by weight or less with respect to 100 parts by weight of the total of the tetracarboxylic dianhydride and diamine used.

<Synthesis of polyamic acid>
The ratio of the tetracarboxylic dianhydride and the diamine used in the polyamic acid synthesis reaction in the present invention is such that the acid anhydride group of the tetracarboxylic dianhydride is 0. A ratio of 2 to 2 equivalents is preferable, and a ratio of 0.3 to 1.2 equivalents is more preferable.
The polyamic acid synthesis reaction is preferably carried out in an organic solvent. The reaction temperature at this time is preferably −20 ° C. to 150 ° C., more preferably 0 to 100 ° C. The reaction time is preferably 0.1 to 24 hours, more preferably 0.5 to 12 hours.

Here, examples of the organic solvent include an aprotic polar solvent, phenol and derivatives thereof, alcohol, ketone, ester, ether, halogenated hydrocarbon, and hydrocarbon.
Specific examples of these organic solvents include, for example, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, N-ethyl-2-pyrrolidone, N, N as the aprotic polar solvent. -Dimethylacetamide, N, N-dimethylformamide, dimethylsulfoxide, γ-butyrolactone, tetramethylurea, hexamethylphosphortriamide, a compound represented by the following formula (1), etc .;
Examples of the phenol derivative include m-cresol, xylenol, halogenated phenol and the like;
Examples of the alcohol include methyl alcohol, ethyl alcohol, isopropyl alcohol, cyclohexanol, ethylene glycol, propylene glycol, 1,4-butanediol, triethylene glycol, and ethylene glycol monomethyl ether;
Examples of the ketone include acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone;
Examples of the ester include ethyl lactate, butyl lactate, methyl acetate, ethyl acetate, butyl acetate, methyl methoxypropionate, ethyl ethoxypropionate, diethyl oxalate, and diethyl malonate;
Examples of the ether include diethyl ether, ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol-n-propyl ether, ethylene glycol-i-propyl ether, ethylene glycol-n-butyl ether, ethylene glycol dimethyl ether, ethylene glycol ethyl ether. Acetate, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, tetrahydrofuran, etc .;
Examples of the halogenated hydrocarbon include dichloromethane, 1,2-dichloroethane, 1,4-dichlorobutane, trichloroethane, chlorobenzene, o-dichlorobenzene and the like;
Examples of the hydrocarbon include hexane, heptane, octane, benzene, toluene, xylene, isoamylpropionate, isoamylisobutyrate, and diisopentyl ether.

Among these organic solvents, one or more selected from the group consisting of an aprotic polar solvent and phenol and derivatives thereof (first group organic solvent), or one or more selected from the first group of organic solvents And a mixture of at least one selected from the group consisting of alcohols, ketones, esters, ethers, halogenated hydrocarbons and hydrocarbons (second group organic solvent). In the latter case, the proportion of the second group organic solvent used is preferably 50% by weight or less, more preferably 40% by weight, based on the total amount of the first group organic solvent and the second group organic solvent. Or less, more preferably 30% by weight or less.
The amount of organic solvent used (a) is such that the total amount (b) of tetracarboxylic dianhydride and diamine is 0.1 to 50% by weight based on the total amount (a + b) of the reaction solution. It is preferable.

  As described above, a reaction solution obtained by dissolving polyamic acid is obtained. This reaction solution may be used as it is for the preparation of the liquid crystal aligning agent, may be used for the preparation of the liquid crystal aligning agent after isolating the polyamic acid contained in the reaction solution, or the isolated polyamic acid was purified. You may use for preparation of a liquid crystal aligning agent. When polyamic acid is dehydrated and cyclized into a polyimide, the above reaction solution may be directly subjected to dehydration and cyclization reaction, or may be subjected to dehydration and cyclization reaction after isolating the polyamic acid contained in the reaction solution. Alternatively, the isolated polyamic acid may be purified and then subjected to a dehydration ring closure reaction. Isolation and purification of the polyamic acid can be performed according to known methods.

<Synthesis of polyimide and polyimide>
The polyimide contained in the liquid crystal aligning agent of the present invention can be obtained by dehydrating and ring-closing imidizing the polyamic acid synthesized as described above.

  The polyimide may be a completely imidized product obtained by dehydrating and cyclizing all of the amic acid structure possessed by the polyamic acid that is the precursor, and only a part of the amic acid structure is dehydrated and cyclized, It may be a partially imidized product in which an imide ring structure coexists. The polyimide in the present invention preferably has an imidation ratio of 30% or more, more preferably 40 to 99%, and still more preferably 45 to 99%. This imidation ratio represents the ratio of the number of imide ring structures to the total of the number of polyimide amic acid structures and the number of imide ring structures in percentage. Here, a part of the imide ring may be an isoimide ring.

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

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

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

<Solution viscosity of polymer>
The polyamic acid and polyimide obtained as described above preferably have a solution viscosity of 10 to 800 mPa · s, when this is a 10% by weight solution, and a solution of 15 to 500 mPa · s. More preferably, it has a viscosity. In addition, the solution viscosity (mPa · s) of the above polymer is a good solvent (for example, γ-butyrolactone, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, N-ethyl). It is a value measured at 25 ° C. using an E-type rotational viscometer for a polymer solution having a concentration of 10% by weight prepared using 2-pyrrolidone or the like.

（式（１）中、Ｒ^１及びＲ^２は、それぞれ独立に、水素原子、炭素数１〜６の炭化水素基、又は当該炭化水素基の炭素−炭素結合間に−Ｏ−を含む１価の基であり、Ｒ^１とＲ^２とが互いに結合して環構造を形成してもよい。Ｒ^３は、炭素数１〜６のアルキル基である。） <Solvent>
The liquid crystal aligning agent of the present invention is constituted by dissolving and containing at least one of polyamic acid and polyimide in an organic solvent. As such a solvent, the liquid crystal aligning agent of the present invention is at least selected from the group consisting of 1,3-dimethyl-2-imidazolidinone, N-ethyl-2-pyrrolidone and a compound represented by the following formula (1). A kind of solvent (B) is contained as an essential component. These solvents (B) all have high boiling points and high solubility of polyamic acid and polyimide. Therefore, even when printing is performed over a long period of time, the solvent volatilization from the printing press is small, and polymer deposition can be suppressed.

(In formula (1), R ¹ and R ² each independently represent a hydrogen atom, a hydrocarbon group having 1 to 6 carbon atoms, or a monovalent group including —O— between the carbon-carbon bonds of the hydrocarbon group. R ¹ and R ² may be bonded to each other to form a ring structure, and R ³ is an alkyl group having 1 to 6 carbon atoms.)

The hydrocarbon group having 1 to 6 carbon atoms in R ¹ and R ² in the formula (1) may be saturated or unsaturated. R ¹ and R ² may include “—O—” between carbon-carbon single bonds of a hydrocarbon group having 1 to 6 carbon atoms. Specific examples of R ¹ and R ² include, for example, an alkyl group having 1 to 6 carbon atoms, an alicyclic hydrocarbon group, an aromatic hydrocarbon group, and “—O— between the carbon-carbon bonds of these groups. And the like. In the formula (1), R ¹ and R ² may be the same as or different from each other.
Here, as the alkyl group having 1 to 6 carbon atoms, for example, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, isobutyl group, tert-butyl group, pentyl group, A hexyl group etc. can be mentioned.
Examples of the alicyclic hydrocarbon group include a cyclopentyl group and a cyclohexyl group. Examples of the aromatic hydrocarbon group include a phenyl group.
R ¹ and R ² may be bonded to each other to form a ring together with the nitrogen atom to which R ¹ and R ² are bonded. Examples of the ring formed by combining R ¹ and R ² with each other include a pyrrolidine ring and a piperidine ring. In addition, a monovalent chain hydrocarbon group such as a methyl group may be bonded to these rings.
R ¹ and R ² are preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and more preferably a hydrogen atom or a methyl group.
The alkyl group having 1 to 6 carbon atoms of R ³ may be linear or branched, and specifically, the groups exemplified in the description of the alkyl group having 1 to 6 carbon atoms of R ¹ and R ² above. Can be mentioned.

Specific examples of the compound represented by the above formula (1) include, for example, 3-butoxy-N, N-dimethylpropanamide, 3-methoxy-N, N-dimethylpropanamide, 3-hexyloxy-N, N- Examples include dimethylpropanamide, isopropoxy-N-isopropyl-propionamide, and n-butoxy-N-isopropyl-propionamide.
From the viewpoint of improving the solubility of the polymer contained in the liquid crystal aligning agent in the solvent, the solvent (B) is preferably used in an amount of 5% by weight or more based on the total solvent contained in the liquid crystal aligning agent. It is more preferable to use the above. Further, the upper limit of the content of the solvent (B) is preferably 90% by weight or less, more preferably 60% by weight or less, and still more preferably 50% by weight with respect to the total solvent contained in the liquid crystal aligning agent. It is as follows. In addition, a solvent (B) can be used individually by 1 type or in combination of 2 or more types.

  Examples of the solvent used for the preparation of the liquid crystal aligning agent of the present invention include N-methyl-2-pyrrolidone, γ-butyrolactone, γ-butyrolactam, N, N— Dimethylformamide, N, N-dimethylacetamide, 4-hydroxy-4-methyl-2-pentanone, ethylene glycol monomethyl ether, butyl lactate, butyl acetate, methyl methoxypropionate, ethyl ethoxypropionate, ethylene glycol methyl Ether, ethylene glycol ethyl ether, ethylene glycol-n-propyl ether, ethylene glycol-i-propyl ether, ethylene glycol-n-butyl ether (butyl cellosolve), ethylene glycol dimethyl ether, ethylene glycol ethyl ether Teracetate, 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, dipropylene glycol monomethyl ether (DPM), diisobutyl ketone, isoamyl propionate, isoamyl isobuty Examples thereof include rate, diisopentyl ether, ethylene carbonate, and propylene carbonate. These can be used alone or in admixture of two or more.

  The liquid crystal aligning agent of the present invention preferably contains dipropylene glycol monomethyl ether (DPM) as the other solvent. By using the solvent (B) and DPM in combination as a solvent to be contained in the liquid crystal aligning agent, long-term printability can be further improved.

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

[Other polymers]
The above other polymers can be used for improving solution properties and electrical properties. Examples of such other polymers include polyamic acid obtained by reacting a diamine not containing the specific diamine and tetracarboxylic dianhydride (hereinafter referred to as “other polyamic acid”), the other polyamic. Polyimide obtained by dehydrating and cyclizing acid (hereinafter referred to as “other polyimide”), polyamic acid ester, polyester, polyamide, polysiloxane, cellulose derivative, polyacetal, polystyrene derivative, poly (styrene-phenylmaleimide) derivative, poly ( And (meth) acrylate. In addition, what was illustrated as a compound used in order to synthesize | combine the said polymer (A) can be mentioned as tetracarboxylic dianhydride and diamine used in order to synthesize | combine another polyamic acid and another polyimide.

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

[Epoxy group-containing compound]
The epoxy group-containing compound can be used to improve the adhesion of the liquid crystal alignment film to the substrate surface. Here, 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, trimethylolpropane triglycidyl ether, 2,2-dibromoneopentyl glycol diglycidyl ether, N, N, N ′, N′-tetraglycidyl-m-xylenediamine 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, N, N, N ′, N′-tetraglycidyl-4,4′-diaminodi Enirumetan, N, N-diglycidyl - benzylamine, N, N-diglycidyl - aminomethyl cyclohexane, N, N-diglycidyl - may be mentioned as preferred cyclohexylamine and the like. In addition, as an example of the epoxy group-containing compound, an epoxy group-containing polyorganosiloxane described in International Publication No. 2009/096598 can also be used.

  When these epoxy compounds are added to the liquid crystal aligning agent, the blending ratio is preferably 40 parts by weight or less, more preferably 0.1 to 30 parts by weight with respect to 100 parts by weight of the total of the polymers contained in the liquid crystal aligning agent. preferable.

[Oxetanyl group-containing compound]
The oxetanyl group-containing compound can be used to improve the mechanical strength of the liquid crystal alignment film and the adhesion to the substrate surface. Here, as the oxetanyl group-containing compound, 1,4-bis {[(3-ethyl-3-oxetanyl) methoxy] methyl} benzene, di [2- (3-oxetanyl) butyl] ether, 1,4-bis [(3-ethyloxetane-3-yl) methoxy] benzene, 1,3-bis [(3-ethyloxetane-3-yl) methoxy] benzene, 4,4′-bis [(3-ethyloxetane-3- Yl) methoxy] biphenyl, 2,2′-bis [(3-ethyl-3-oxetanyl) methoxy] biphenyl, 3,3 ′, 5,5′-tetramethyl [4,4′-bis (3-ethyloxetane) -3-yl) methoxy] biphenyl, 2,7-bis [(3-ethyloxetane-3-yl) methoxy] naphthalene, 4,4′-bis [(1-ethyl-3-oxetanyl) methyl] thi Dibenzenethioether, 2,3-bis [(3-ethyloxetane-3-yl) methoxymethyl] norbornane, 2,2-dimethyl-1,3-O-bis [(3-ethyloxetane-3-yl) methyl ] -Propane-1,3-diol, 2,4,6-O-tris [(3-ethyloxetane-3-yl) methyl] cyanuric acid, oxetanylsilsesquioxane, 3-ethyl-3-hydroxymethyloxetane Silicon alkoxide, ETARNACOLL OXBP (manufactured by Ube Industries, Ltd.), 3,3 ′-(1,3- (2-methylenyl) propanediylbis (oxymethylene)) bis- (3-ethyloxetane), 1 , 2-bis [(3-ethyl-3-oxetanylmethoxy) methyl] ethane, dicyclopentenylbis (3-ethyl-3-oxetani Rumethyl) ether, triethylene glycol bis (3-ethyl-3-oxetanylmethyl) ether, trimethylolpropane tris (3-ethyl-3-oxetanylmethyl) ether, 1,4-bis (3-ethyl-3-oxetanylmethoxy) ) Butane, pentaerythritol tris (3-ethyl-3-oxetanylmethyl) ether, ditrimethylolpropane tetrakis (3-ethyl-3-oxetanylmethyl) ether, and the like.

  When mix | blending an oxetanyl group containing compound, the compounding ratio becomes like this. Preferably it is 40 weight part or less with respect to a total of 100 weight part of a polymer, More preferably, it is 30 weight part or less.

[Functional silane compounds]
The said functional silane compound can be used in order to improve the printability of a liquid crystal aligning agent. Examples of such functional silane compounds include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 2-aminopropyltrimethoxysilane, 2-aminopropyltriethoxysilane, N- (2-aminoethyl). ) -3-Aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-ureidopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, N-ethoxycarbonyl-3- 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-trimethoxysilyl-3,6-diazanonyl acetate , 9-triethoxysilyl-3,6-diazanonyl acetate, methyl 9-trimethoxysilyl-3,6-diazananoate, methyl 9-triethoxysilyl-3,6-diazananoate, N-benzyl-3- Aminopropyltrimethoxysilane, N-benzyl-3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltriethoxysilane, glycidoxymethyltrimethoxysilane, Glycidoxymethyltriethoxysilane, 2-glycidoxyethylate Silane, 2-glycidoxyethyl triethoxysilane, 3-glycidoxypropyltrimethoxysilane, can be mentioned 3-glycidoxypropyl triethoxysilane.

  When these functional silane compounds are added to the liquid crystal aligning agent, the blending ratio is preferably 2 parts by weight or less, more preferably 0.02 to 0.2 parts by weight, based on 100 parts by weight of the total polymer.

  The solid content concentration in the liquid crystal aligning agent of the present invention (the ratio of the total weight of components other than the solvent of the liquid crystal aligning agent to the total weight of the liquid crystal aligning agent) is appropriately selected in consideration of viscosity, volatility, and the like. The range is preferably 1 to 10% by weight. That is, the liquid crystal aligning agent of the present invention is applied to the substrate surface as described later, and preferably heated to form a coating film that is a liquid crystal alignment film or 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 the coating film is too small to obtain a good liquid crystal alignment film. On the other hand, 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, and the viscosity of the liquid crystal aligning agent increases and the coating characteristics are increased. Is inferior.

The particularly preferable range of the solid content concentration varies depending on the method used when the liquid crystal aligning agent is applied to the substrate. For example, when the spinner method is used, the solid content concentration is particularly preferably in the range of 1.5 to 4.5% by weight. In the case of the printing method, it is particularly preferable that the solid content concentration is in the range of 3 to 9% by weight, and thereby the solution viscosity is in the range of 12 to 50 mPa · s. In the case of the inkjet method, it is particularly preferable that the solid content concentration is in the range of 1 to 5% by weight, and thereby the solution viscosity is in the range of 3 to 15 mPa · s.
The temperature at the time of preparing the liquid crystal aligning agent of this invention becomes like this. Preferably it is 10-50 degreeC, More preferably, it is 20-30 degreeC.

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

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

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

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

  After the application of the liquid crystal aligning agent, preheating (pre-baking) is preferably performed for the purpose of preventing dripping of the applied aligning agent. The pre-baking temperature is preferably 30 to 200 ° C, more preferably 40 to 150 ° C, and particularly preferably 40 to 100 ° C. The pre-bake time is preferably 0.25 to 10 minutes, more preferably 0.5 to 5 minutes. Then, a baking (post-baking) process is implemented for the purpose of removing a solvent completely and heat imidating the amic acid structure which exists in a polymer as needed. The firing (post-bake) temperature is preferably 80 to 300 ° C, more preferably 120 to 250 ° C. The post-bake time is preferably 5 to 200 minutes, more preferably 10 to 100 minutes. Thus, the film thickness of the formed film is preferably 0.001 to 1 μm, more preferably 0.005 to 0.5 μm.

  (1-2) When manufacturing an IPS type or FSS type liquid crystal display element, an electrode forming surface of a substrate provided with an electrode made of a transparent conductive film or a metal film patterned in a comb shape, and an electrode are provided. The liquid crystal aligning agent of this invention is each apply | coated to one surface of the counter substrate which is not, and then a coating film is formed by heating each application surface. About the material of the board | substrate used at this time and a transparent conductive film, the coating method, the heating conditions after application | coating, the patterning method of a transparent conductive film or a metal film, the pre-processing of a board | substrate, and the preferable film thickness of the coating film formed are the said ( It is the same as 1-1). As the metal film, for example, a film made of a metal such as chromium can be used.

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

[Step (2): rubbing treatment]
When manufacturing a TN type, STN type, IPS type or FFS type liquid crystal display element, the coating film formed in the above step (1) is a roll around which a cloth made of fibers such as nylon, rayon, cotton, etc. is wound. A rubbing process is performed to rub in a certain direction. Thereby, the orientation ability of a liquid crystal molecule is provided to a coating film, and it becomes a liquid crystal aligning film. On the other hand, when manufacturing a VA type liquid crystal display element, the coating film formed in the step (1) can be used as it is as a liquid crystal alignment film, but the coating film may be subjected to a rubbing treatment.

  Furthermore, with respect to the liquid crystal alignment film formed as described above, a treatment for changing the pretilt angle of a part of the liquid crystal alignment film by irradiating a part of the liquid crystal alignment film with ultraviolet rays, After forming a resist film in part and performing a rubbing process in a direction different from the previous rubbing process, a process for removing the resist film is performed so that the liquid crystal alignment film has different liquid crystal alignment capabilities for each region. Good. In this case, it is possible to improve the visibility characteristics of the obtained liquid crystal display element.

[Step (3): Construction of liquid crystal cell]
Two substrates on which the liquid crystal alignment film is formed as described above are prepared, and a liquid crystal cell is manufactured by disposing a liquid crystal between the two substrates disposed to face each other. Here, when the rubbing treatment is performed on the coating film, the two substrates are disposed to face each other so that the rubbing directions in the respective coating films are at a predetermined angle, for example, orthogonal or antiparallel.

In order to manufacture a liquid crystal cell, the following two methods are mentioned, for example.
The first method is a conventionally known method. First, two substrates are arranged to face each other through a gap (cell gap) so that the respective liquid crystal alignment films are opposed to each other, and the peripheral portions of the two substrates are bonded using a sealant, and the substrate surface and the sealant are bonded. A liquid crystal cell can be manufactured by injecting and filling liquid crystal into the cell gap partitioned by the step, and then sealing the injection hole.
The second method is a method called an ODF (One Drop Fill) method. For example, an ultraviolet curable sealing material is applied to a predetermined location on one of the two substrates on which the liquid crystal alignment film is formed, and liquid crystal is dropped to predetermined locations on the surface of the liquid crystal alignment film. Thereafter, the other substrate is bonded so that the liquid crystal alignment film faces, and the liquid crystal is spread over the entire surface of the substrate, and then the entire surface of the substrate is irradiated with ultraviolet light to cure the sealant, thereby manufacturing a liquid crystal cell. be able to.
Regardless of which method is used, the liquid crystal cell produced as described above is further heated to a temperature at which the liquid crystal used takes an isotropic phase and then gradually cooled to room temperature. It is desirable to remove.
And the liquid crystal display element of this invention can be obtained by bonding a polarizing plate on the outer surface of a liquid crystal cell.

As the sealing agent, for example, an epoxy resin containing a curing agent and aluminum oxide spheres as a spacer can be used.
Examples of the liquid crystal include nematic liquid crystal and smectic liquid crystal. Among them, nematic liquid crystal is preferable. For example, Schiff base liquid crystal, azoxy liquid crystal, biphenyl liquid crystal, phenylcyclohexane liquid crystal, ester liquid crystal, terphenyl liquid crystal, biphenyl. Cyclohexane liquid crystals, pyrimidine liquid crystals, dioxane liquid crystals, bicyclooctane liquid crystals, cubane liquid crystals, and the like can be used. Further, cholesteric liquid crystals such as cholestyl chloride, cholesteryl nonate, and cholesteryl carbonate; chiral agents such as those sold under the trade names “C-15” and “CB-15” (manufactured by Merck & Co., Inc.). A ferroelectric liquid crystal such as p-decyloxybenzylidene-p-amino-2-methylbutylcinnamate may be added and used.
As a polarizing plate to be bonded to the outer surface of the liquid crystal cell, a polarizing film or an H film itself in which a polarizing film called an “H film” in which iodine is absorbed while stretching and aligning polyvinyl alcohol is sandwiched between cellulose acetate protective films The polarizing plate which consists of can be mentioned.

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

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

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

<Synthesis of polymer (A)>
[Synthesis Example 1: Synthesis of polyimide (PI-1)]
2,2.4 g (0.1 mol) of 2,3,5-tricarboxycyclopentyl acetic acid dianhydride (TCA) as tetracarboxylic dianhydride, 2.2 g (0.02 mol) of p-phenylenediamine (PDA) as diamine ), 1- (4-aminophenyl) -2,3-dihydro-1,3,3-trimethyl-1H-indene-5-amine / 1- (4-aminophenyl) -2,3-dihydro-1, A mixture of 3,3-trimethyl-1H-indene-6-amine (TMDA) 13.3 g (0.05 mol), cholestanyl 3,5-diaminobenzoate (HCDA) 10.4 g (0.02 mol) and choles 4.9 g (0.01 mol) of Tanyloxy-2,4-diaminobenzene (HCODA) was dissolved in 213 g of N-methyl-2-pyrrolidone (NMP) and reacted at 60 ° C. for 6 hours. It was carried out to obtain a solution containing a polyamic acid 20 wt%. About the obtained polyamic acid solution, NMP was added and the solution viscosity measured as a solution of polyamic acid density | concentration of 10 weight% was 85 mPa * s.

  Next, 494 g of NMP was added to the obtained polyamic acid solution, 11.8 g of pyridine and 15.3 g of acetic anhydride were added, and dehydration ring closure reaction was performed at 110 ° C. for 4 hours. After the dehydration cyclization reaction, the solvent in the system was replaced with new NMP (by this operation, pyridine and acetic anhydride used in the dehydration cyclization reaction were removed from the system. The same applies hereinafter), whereby the imidation rate was about 70. A solution containing 22% by weight of polyimide (PI-1) was obtained. A small amount of the obtained polyimide solution was collected, NMP was added, and the solution viscosity measured as a solution having a polyimide concentration of 10% by weight was 55 mPa · s.

[Synthesis Example 2: Synthesis of polyimide (PI-2)]
22.5 g (0.1 mol) of TCA as tetracarboxylic dianhydride, 6.5 g (0.06 mol) of PDA, 5.3 g (0.02 mol) of TMDA and 10.5 g (0.02 mol) of HCDA as diamines It melt | dissolved in 179 g of NMP, it reacted at 60 degreeC for 6 hours, and obtained the solution containing 20 weight% of polyamic acids. About the obtained polyamic acid solution, NMP was added and the solution viscosity measured as a solution with a polyamic acid density | concentration of 10 weight% was 105 mPa * s.

  Next, 416 g of NMP was added to the obtained polyamic acid solution, 11.9 g of pyridine and 15.4 g of acetic anhydride were added, and dehydration ring closure reaction was performed at 110 ° C. for 4 hours. After the dehydration ring-closing reaction, the solvent in the system was replaced with new NMP to obtain a solution containing 22% by weight of polyimide (PI-2) having an imidization ratio of about 63%. A small amount of the obtained polyimide solution was taken, NMP was added, and the solution viscosity measured as a solution having a polyimide concentration of 10% by weight was 58 mPa · s.

[Synthesis Example 3: Synthesis of polyimide (PI-3)]
TCA 22.4 g (0.10 mol) as tetracarboxylic dianhydride, PDA 6.5 g (0.06 mol), TMDA 2.7 g (0.01 mol), HCDA 10.4 g (0.02 mol) and HCODA4 as diamine 0.9 g (0.01 mol) was dissolved in 187 g of NMP and reacted at 60 ° C. for 6 hours to obtain a solution containing 20% by weight of polyamic acid. About the obtained polyamic acid solution, NMP was added and the solution viscosity measured as a solution with a polyamic acid density | concentration of 10 weight% was 102 mPa * s.

  Next, 435 g of NMP was added to the obtained polyamic acid solution, 7.9 g of pyridine and 10.2 g of acetic anhydride were added, and dehydration ring closure reaction was performed at 110 ° C. for 4 hours. After the dehydration ring-closing reaction, the solvent in the system was replaced with new NMP to obtain a solution containing 22% by weight of polyimide (PI-3) having an imidation ratio of about 51%. A small amount of the obtained polyimide solution was collected, NMP was added, and the solution viscosity measured as a solution having a polyimide concentration of 10% by weight was 54 mPa · s.

[Synthesis Example 4: Synthesis of polyimide (PI-4)]
2,4,6,8-tetracarboxybicyclo [3.3.0] octane-2: 4,6: 8-dianhydride (BODA) 25.1 g (0.10 mol) as tetracarboxylic dianhydride As a diamine, PDA 2.2 g (0.02 mol), TMDA 13.3 g (0.05 mol), HCDA 10.5 g (0.02 mol) and HCODA 5.0 g (0.01 mol) were dissolved in 224 g of NMP, The reaction was carried out at 0 ° C. for 6 hours to obtain a solution containing 20% by weight of polyamic acid. About the obtained polyamic acid solution, NMP was added and the solution viscosity measured as a solution with a polyamic acid density | concentration of 10 weight% was 60 mPa * s.

  Next, 520 g of NMP was added to the obtained polyamic acid solution, 11.9 g of pyridine and 15.3 g of acetic anhydride were added, and dehydration ring closure reaction was performed at 110 ° C. for 4 hours. After the dehydration ring closure reaction, the solvent in the system was replaced with new NMP to obtain a solution containing 22% by weight of polyimide (PI-4) having an imidation ratio of about 66%. A small amount of the obtained polyimide solution was taken, NMP was added, and the solution viscosity measured as a solution having a polyimide concentration of 10% by weight was 44 mPa · s.

[Synthesis Example 5: Synthesis of polyimide (PI-5)]
TCA 22.5 g (0.1 mol) as tetracarboxylic dianhydride, PDA 7.5 g (0.07 mol), HCDA 10.5 g (0.02 mol) and HCODA 5.0 g (0.01 mol) as diamine The resultant was dissolved in 182 g of NMP and reacted at 60 ° C. for 6 hours to obtain a solution containing 20% by weight of polyamic acid. About the obtained polyamic acid solution, NMP was added and the solution viscosity measured as a solution with a polyamic acid concentration of 10% by weight was 95 mPa · s.

  Next, 423 g of NMP was added to the obtained polyamic acid solution, 11.9 g of pyridine and 15.4 g of acetic anhydride were added, and dehydration ring closure reaction was performed at 110 ° C. for 4 hours. After the dehydration ring closure reaction, the solvent in the system was replaced with new NMP to obtain a solution containing 22% by weight of polyimide (PI-5) having an imidation ratio of about 67%. A small amount of the obtained polyimide solution was taken, NMP was added, and the solution viscosity measured as a solution having a polyimide concentration of 10% by weight was 49 mPa · s.

[Synthesis Example 6: Synthesis of polyimide (PI-6)]
TCA 22.3 g (0.1 mol) as tetracarboxylic dianhydride, 43.8'-diaminodiphenylmethane 13.8 g (0.07 mol), HCDA 10.4 g (0.02 mol) and HCODA 4.9 g (0 0.01 mol) was dissolved in 206 g of NMP and reacted at 60 ° C. for 6 hours to obtain a solution containing 20% by weight of polyamic acid. About the obtained polyamic acid solution, NMP was added and the solution viscosity measured as a solution with a polyamic acid density | concentration of 10 weight% was 100 mPa * s.

  Next, 478 g of NMP was added to the obtained polyamic acid solution, 11.8 g of pyridine and 15.2 g of acetic anhydride were added, and dehydration ring closure reaction was performed at 110 ° C. for 4 hours. After the dehydration ring closure reaction, the solvent in the system was replaced with new NMP to obtain a solution containing 22% by weight of polyimide (PI-6) having an imidation ratio of about 66%. A small amount of the obtained polyimide solution was taken, NMP was added, and the solution viscosity measured as a solution having a polyimide concentration of 10% by weight was 59 mPa · s.

[Synthesis Example 7: Synthesis of polyimide (PI-7)]
A polyamic acid solution was obtained in the same manner as in Synthesis Example 1 except that 1,3-dimethyl-2-imidazolidinone (DMI) was used instead of NMP. About the obtained polyamic acid solution, the solution viscosity measured by adding DMI as a solution with a polyamic acid concentration of 10% by weight was 86 mPa · s.
Next, polyimide was synthesized using the obtained polyamic acid solution. The synthesis was performed in the same manner as in Synthesis Example 1 except that DMI was used in place of NMP, thereby obtaining a solution containing 22% by weight of polyimide (PI-7) having an imidization ratio of about 68%. A small amount of the obtained polyimide solution was taken, and the solution viscosity measured as a solution having a polyimide concentration of 10% by weight by adding DMI was 56 mPa · s.

[Synthesis Example 8: Synthesis of polyimide (PI-8)]
A polyamic acid solution was obtained in the same manner as in Synthesis Example 2 except that N-ethyl-2-pyrrolidone (NEP) was used instead of NMP. About the obtained polyamic acid solution, NEP was added and the solution viscosity measured as a solution with a polyamic acid density | concentration of 10 weight% was 101 mPa * s.
Next, polyimide was synthesized using the obtained polyamic acid solution. The synthesis was performed in the same manner as in Synthesis Example 2 except that NEP was used in place of NMP, thereby obtaining a solution containing 22% by weight of polyimide (PI-8) having an imidization ratio of about 64%. A small amount of the obtained polyimide solution was taken, NEP was added, and the solution viscosity measured as a solution having a polyimide concentration of 10% by weight was 56 mPa · s.

<Preparation of liquid crystal aligning agent>
[Example 1]
NMP, ethylene glycol-mono-n-butyl ether (BC) and 1,3-dimethyl-2-imidazolidinone (DMI) are added as solvents to a solution containing polyimide (PI-1) as a polymer, and a solvent composition Was a solution having NMP: BC: DMI = 30: 50: 20 (weight ratio) and a solid content concentration of 6.5% by mass. A liquid crystal aligning agent (S-1) was prepared by filtering this solution using a filter having a pore diameter of 1 μm.
[Examples 2 to 23 and Comparative Examples 1 to 6]
Liquid crystal aligning agents (S-2) to (S-23) and (SR-1) to (SR-1) are the same as in Example 1 except that the polyimide and solvent composition used are changed as shown in Table 1 below. (SR-6) was prepared.

<Evaluation of printability>
About the liquid crystal aligning agent prepared above, the printability (long-time printability) when printing on a substrate was performed for a long time was evaluated. Evaluation was performed as follows. First, for each of the prepared liquid crystal alignment agents, using a liquid crystal alignment film printer (Nissha Printing Co., Ltd., Angstromer type “S40L-532”), the dropping amount of the liquid crystal alignment agent on the anilox roll is determined. It apply | coated on the transparent electrode surface of the glass substrate with a transparent electrode which consists of an ITO film | membrane on the conditions of 20 drops (about 0.2g). The application to the substrate was performed 20 times using a new substrate at 1 minute intervals.
Subsequently, the liquid crystal aligning agent was dispensed on the anilox roll at one minute intervals (one way), and each time the operation of bringing the anilox roll into contact with the printing plate (hereinafter referred to as idle operation) was performed 10 times in total (during this time, Do not print on glass substrate). This idling operation is not performed in the actual manufacturing process of the liquid crystal display element, but is an operation performed to intentionally perform the printing of the liquid crystal aligning agent under severe conditions.

After 10 times of idling, this printing was performed using a glass substrate. In this printing, after the idling operation, 5 substrates are thrown at 30 second intervals, and each substrate after applying the liquid crystal aligning agent is heated (prebaked) at 80 ° C. for 1 minute to remove the solvent, and then 200 ° C. Was heated (post-baked) for 10 minutes to form a coating film having a thickness of about 80 nm. Long-term printability was evaluated by observing this coating film with a microscope having a magnification of 20 times. Evaluation is excellent (○) when no polyimide deposition is observed from the first printing after the blank operation, and polyimide deposition is observed at the first printing after the blank operation, but the printing is performed five times. The case where the precipitation of polyimide was not observed in the meantime was good (Δ), and the case where the precipitation of polyimide was observed even after the main printing was repeated 5 times was judged as bad (x). The evaluation results are shown in Table 1 below. In addition, it has been experimentally known that with a liquid crystal aligning agent having good printability, the deposition of polyimide is improved (disappeared) while the substrate is continuously charged.
Furthermore, the number of idling operations was changed to 15, 20, and 25, and the long-term printability of the liquid crystal aligning agent was evaluated in the same manner as described above. The evaluation results are also shown in Table 1 below.

In addition, the symbol of the solvent composition in Table 1 has the following meaning, respectively.
a: N-methyl-2-pyrrolidone (NMP)
b: ethylene glycol mono-n-butyl ether (BC)
c: γ-butyrolactone (GBL)
d: 1,3-dimethyl-2-imidazolidinone (DMI)
e: N-ethyl-2-pyrrolidone (NEP)
f: 3-methoxy-N, N-dimethylpropanamide g: 3-butoxy-N, N-dimethylpropanamide h: dipropylene glycol monomethyl ether (DPM)

As shown in Table 1, in any of the liquid crystal aligning agents of the examples, no polyimide deposition was observed from the first main printing in the main printing after 10 idlings. Further, even if the number of idling operations is increased to 20 times or 25 times, no polyimide deposition is observed from the first printing, or even if it is observed, polyimide deposition does not occur until 5 printings are completed. Disappeared. On the other hand, in the liquid crystal aligning agent of the comparative example, when the number of idling operations was increased to 20, the deposition of polyimide was observed in all five main printings. From this result, in the liquid crystal aligning agent of Examples 1-23, a polyimide is hard to precipitate compared with the thing of a comparative example, and when printing is performed continuously for a long time, printability (long-time printability) is favorable. It turns out that.
Moreover, from the results of Examples 6, 12, and 14, it was found that long-term printability can be further improved by using DPM together as a solvent.

Claims (4)

A) Tetracarboxylic dianhydride and 1- (4-aminophenyl) -2,3-dihydro-1,3,3-trimethyl-1H-indene-5-amine and 1- (4-aminophenyl)- A polyamic acid obtained by reacting a diamine containing at least one of 2,3-dihydro-1,3,3-trimethyl-1H-indene-6-amine and a polyamic acid obtained by dehydrating and ring-closing the polyamic acid At least one polymer (A) selected from the group consisting of polyimides;
B) at least one solvent (B) selected from the group consisting of 1,3-dimethyl-2-imidazolidinone, N-ethyl-2-pyrrolidone and a compound represented by the following formula (1);
A liquid crystal aligning agent characterized by containing.

(In formula (1), R ¹ and R ² each independently represent a hydrogen atom, a hydrocarbon group having 1 to 6 carbon atoms, or a monovalent group including —O— between the carbon-carbon bonds of the hydrocarbon group. R ¹ and R ² may be bonded to each other to form a ring structure, and R ³ is an alkyl group having 1 to 6 carbon atoms.)   The liquid crystal aligning agent of Claim 1 whose content of the said solvent (B) is 10 weight% or more of the whole solvent.   The polymer (A) has 2,3,5-tricarboxycyclopentylacetic acid dianhydride and 2,4,6,8-tetracarboxybicyclo [3.3.0] octane as the tetracarboxylic dianhydride. The liquid crystal aligning agent of Claim 1 or 2 synthesize | combined using the compound containing at least any one of -2: 4,6: 8-dianhydride.   The liquid crystal aligning agent as described in any one of Claims 1 thru | or 3 which further contains dipropylene glycol monomethyl ether as a solvent.