JP5668931B2 - Liquid crystal alignment agent - Google Patents

Description

The present invention relates to a liquid crystal aligning agent.
More specifically, the present invention relates to a liquid crystal aligning agent that exhibits good reworkability in a manufacturing process of a liquid crystal alignment film, can form a liquid crystal alignment film excellent in water resistance, and is excellent in printability.

Currently, TN (Twisted Nematic), STN (Super Twisted Nematic), VA (Vertical Alignment), IPS (In-Plane Switching), OCB (Optical Compensated Bend), etc. It has been known.
As materials for the liquid crystal alignment film having a function of aligning liquid crystal molecules in these liquid crystal display elements, resin materials such as polyamic acid, polyimide, polyamide, and polyester are known, and in particular, a liquid crystal alignment film made of polyamic acid or polyimide. Is excellent in heat resistance, mechanical strength, affinity with liquid crystal, etc., and is used in many liquid crystal display elements (Patent Documents 1 to 6).
Such a liquid crystal alignment film is formed by applying a liquid crystal aligning agent on a substrate to form a coating film, and subjecting the coating film to a rubbing treatment or a light irradiation treatment as necessary. Next, a pair of two substrates on which a liquid crystal alignment film is formed is used as a pair, and a liquid crystal cell is configured by sandwiching liquid crystal molecules in the gap. Here, it is known that electrical characteristics such as voltage holding ratio may be deteriorated between the formation of the liquid crystal alignment film and the configuration of the liquid crystal cell. This is believed to be due to the deterioration of the formed liquid crystal alignment film by absorbing moisture in the air when exposed to air. In order to improve the water absorption deterioration as described above, it has been proposed to add a compound having an epoxy group to the liquid crystal aligning agent (Patent Document 7), which gives a certain effect.

By the way, a defective substrate (a substrate on which a film including defects such as pinholes in coating and uneven coating) formed in the liquid crystal alignment film forming process in liquid crystal panel production is peeled off from the defective coating on the substrate. In many cases, the substrate is reused (reworked). Therefore, from such a viewpoint, a liquid crystal alignment film material having good peelability is desired. However, it has been pointed out that a liquid crystal alignment film formed from a liquid crystal aligning agent blended with a compound having an epoxy group for the purpose of reducing the above water absorption deterioration is insufficient in releasability during rework.
In addition, liquid crystal alignment agents with excellent printability are desired to reduce the probability of the appearance of defective coatings that require rework as much as possible under the recent severe cost reduction requirements in the liquid crystal display element industry. It is rare.

JP-A-4-153622 JP 60-107020 A JP 56-91277 A U.S. Pat. No. 5,928,733 Japanese Patent Laid-Open No. 62-165628 Japanese Patent Laid-Open No. 11-258605 JP-A-6-222366 JP-A-6-281937 JP-A-5-107544 JP 2010-97188 A

The present invention has been made in view of the above circumstances, and its purpose is:
Even if there is a significant time exposed to air after the formation of the liquid crystal alignment film, it has water resistance that does not cause deterioration due to water absorption of the film, and it has excellent peelability once formed. An object of the present invention is to provide a liquid crystal alignment film material having excellent printability.
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 are:
A liquid crystal aligning agent comprising a polyamic acid obtained by reacting a tetracarboxylic dianhydride and a diamine, and at least one polymer selected from the group consisting of polyimides formed by dehydrating and ring-closing the polyamic acid,
The diamine is represented by the following formula (A1)

(In Formula (A1), R ¹ is an alkyl group having 1 to 6 carbon atoms;
R ² is each an alkyl group having 1 to 6 carbon atoms, a halogen atom, a cyano group, or a hydroxyl group:
X ¹ is a single bond, a methylene group, an alkylene group having 2 to 6 carbon atoms, a phenylene group or a cyclohexylene group, provided that the alkylene group may be interrupted by an ether bond or an ester bond. The phenylene group and the cyclohexylene group may each be substituted by an alkyl group having 1 to 4 carbon atoms, an alkylene group having 1 to 4 carbon atoms, a hydroxyl group, a halogen atom or a cyano group;
a is an integer from 0 to 5;
b is an integer from 0 to 4;
c is an integer of 0-3. )
And a compound having a carboxyl group and two amino groups are achieved by the liquid crystal aligning agent.

The liquid crystal aligning agent of the present invention provides a liquid crystal aligning film that does not cause deterioration such as deterioration of display characteristics such as deterioration of electrical characteristics even if there is a significant time exposed to air after the liquid crystal aligning film is formed. Moreover, it is excellent in the peelability of the coating film once formed. Furthermore, the liquid crystal aligning agent of this invention is excellent in printability, and the probability that the defective coating film which needs rework will appear is reduced as much as possible.
A liquid crystal display element comprising a liquid crystal alignment film formed from the liquid crystal aligning agent of the present invention is excellent in display quality and suppressed in cost associated with rework. Therefore, 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, portable information terminals, digital cameras, cellular phones, various types. Used in display devices such as monitors and liquid crystal televisions.

Hereinafter, the present invention will be described in detail.
As described above, the liquid crystal aligning agent of the present invention is at least one selected from the group consisting of a polyamic acid obtained by reacting a tetracarboxylic dianhydride and a diamine and a polyimide obtained by dehydrating and ring-closing the polyamic acid. Containing a polymer,
However, the diamine includes a compound represented by the above formula (A1) and a compound having a carboxyl group and two amino groups.

<Tetracarboxylic dianhydride>
Examples of the tetracarboxylic dianhydride in the present invention include aliphatic tetracarboxylic dianhydrides, alicyclic tetracarboxylic dianhydrides, aromatic tetracarboxylic dianhydrides, and the like. Specific examples of these include aliphatic tetracarboxylic dianhydrides such as butane tetracarboxylic 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 and the like;
As aromatic tetracarboxylic dianhydride, for example, pyromellitic dianhydride can be mentioned, respectively,
Tetracarboxylic dianhydrides described in Patent Document 10 (Japanese Patent Laid-Open No. 2010-97188) can be used.

Among these, the tetracarboxylic dianhydride used for synthesizing the polyamic acid preferably includes an alicyclic tetracarboxylic dianhydride, and 2,3,5-tricarboxycyclopentylacetic acid dianhydride. Anhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 3,5,6-tricarboxy-2-carboxymethylnorbornane-2: 3,5: 6-dianhydride and 2,4,4 More preferably, it contains at least one selected from the group consisting of 6,8-tetracarboxybicyclo [3.3.0] octane-2: 4,6: 8-dianhydride, Tricarboxycyclopentylacetic acid dianhydride, 3,5,6-tricarboxy-2-carboxymethylnorbornane-2: 3,5: 6-dianhydride and 2, , 6,8-tetracarboxybicyclo [3.3.0] octane-2: 4,6: 8-dianhydride, more preferably including at least one selected from the group consisting of 2,3, It is preferable that it contains 5-tricarboxycyclopentyl acetic acid dianhydride.
Examples of the tetracarboxylic dianhydride used to synthesize the polyamic acid include the alicyclic tetracarboxylic dianhydrides (preferably 2,3,5-tricarboxycyclopentylacetic dianhydride, 1, 2,3,4-cyclobutanetetracarboxylic dianhydride, 3,5,6-tricarboxy-2-carboxymethylnorbornane-2: 3,5: 6-dianhydride and 2,4,6,8-tetra At least one selected from the group consisting of carboxybicyclo [3.3.0] octane-2: 4,6: 8-dianhydride, more preferably 2,3,5-tricarboxycyclopentylacetic acid dianhydride, 3 , 5,6-tricarboxy-2-carboxymethylnorbornane-2: 3,5: 6-dianhydride and 2,4,6,8-tetracarboxybicyclo [3.3 0] octane-2: 4,6: 8-dianhydride, particularly preferably 2,3,5-tricarboxycyclopentylacetic acid dianhydride), all tetracarboxylic dianhydride The content is preferably 10 mol% or more, more preferably 20 mol% or more. Tetracarboxylic acid dianhydride consisting of at least one selected from the group consisting of 2,3,5-tricarboxycyclopentylacetic acid dianhydride and 1,2,3,4-cyclobutanetetracarboxylic dianhydride More preferably, it is most preferable that it consists only of 2,3,5-tricarboxycyclopentyl acetic acid dianhydride.

<Diamine>
The diamine in the present invention is a compound represented by the above formula (A1) (hereinafter referred to as “diamine (1)”) and a compound having a carboxyl group and two amino groups (hereinafter referred to as “diamine (2)”). ).
The diamine in the present invention may be composed only of diamine (1) and diamine (2), or in addition to diamine (1) and diamine (2), other diamines (hereinafter referred to as “diamine (3)”. May be contained).
X ¹ in the diamine (1) is a single bond;
a is 3;
b and c are each preferably 0. As the diamine (1), 1- (4-aminophenyl) -2,3-dihydro-1,3,3-trimethyl-1H-indene-5-amine, that is, the following formula (A1-1)

It is preferable to use a compound represented by the above from the viewpoints of availability and peelability of the liquid crystal alignment film described.
The number of carboxyl groups in the diamine (2) is preferably 1 to 4. As such diamine (2), preferably the following formula (A2)

(In the formula (A2), n is an integer of 0 to 2;
each d is an integer of 0 to 4, provided that when a plurality of d are present, each d may be the same or different;
R ³ is a single bond, a methylene group, an alkylene group having 2 to 6 carbon atoms, or a cyclohexylene group, respectively, provided that the alkylene group may be interrupted by an ether bond or an ester bond;
X ² is a single bond, a methylene group, a fluoromethylene group, an alkylene group having 2 to 4 carbon atoms, a fluoroalkylene group having 2 to 4 carbon atoms, an oxygen atom, a carbonyl group, ^* -COO-, ^* -OCO-, ^* - ^NH-, * ^-CONH-, * -NHCO- (in the above, "*" is a bond marked with this represents that the face to the left of the formula (A2).) or the following formula ^(X 2 -1)

(Wherein (X 2 ^-1), R ⁴ is a single bond, a methylene group, an alkylene group or a cyclohexylene group having 2 to 6 carbon atoms, provided that the alkylene group course is interrupted by an ether bond or an ester bond May be;
R ⁵ is a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or a group —R ⁶ COOH (where R ⁶ is a single bond, a methylene group, an alkylene group having 2 to 6 carbon atoms, or a cyclohexylene group, provided that The alkylene group may be interrupted by an ether bond or an ester bond. )
The number of carboxyl groups in the formula (A2) is an integer of 1 or more. )
It is a compound represented by these.
R ³ in the above formula (A2) is preferably a methylene group or an alkylene group having 2 to 5 carbon atoms. The number of carboxyl groups in formula (A2) is preferably an integer of 1 to 4.
The compound represented by the formula (A2) is a compound in which at least one of d is 1 and the group X ² is not a group represented by the formula (X ² -1) in the formula (A2). Or a compound in which all of d in the formula (A2) are 0 and the group X ² is a group represented by the formula (X ² -1).
More preferable examples of the compound represented by the above formula (A2) include, for example, the following formulas (A2-1) to (A2-5):

(In the above formula, each X ² has the same meaning as X ² in the above formula (A2);
R ⁵ is an alkyl group having 1 to 6 carbon atoms;
d is an integer of 1 to 4 each;
each e is an integer from 1 to 5;
f is an integer of 0 to 4, respectively, provided that two fs are not 0 at the same time. )
It is a compound represented by each of these. D in the above formulas (A2-1) and (A2-5) and f in the above formula (A2-2) are each preferably 1.
As the compound represented by the above formula (A2), a compound represented by the above formula (A2-1), (A2-2) or (A2-5) is preferable. 3,5-diaminobenzoic acid, the following formulas (A2-2-1), (A2-2-2) and (A2-5-1)

^{(X 2} in the formula (A2-2-2) is synonymous with ^{X 2} in the formula (A2-2), f is an integer from 1 to 4.)
The compound represented by each of these can be mentioned.
The diamine (3) is a diamine other than the diamine (1) and the diamine (2). As the diamine (3), a diamine having a group having a function of vertically aligning liquid crystal molecules (hereinafter referred to as “diamine (3-1)”) and other diamines (hereinafter referred to as “diamine (3-2)”). ")".
The diamine (3-1) has a structure in which two or more 6-membered rings are connected to an alkyl group having 4 to 20 carbon atoms, a fluoroalkyl group having 4 to 20 carbon atoms, an alkoxyl group having 4 to 20 carbon atoms. A diamine having a group or a group having a steroid structure is preferred. Here, a diamine having a group having a structure in which two or more 6-membered rings are connected or a group having a steroid structure is further an alkyl group having 4 to 20 carbon atoms, a fluoroalkyl group having 4 to 20 carbon atoms, or a carbon number having 4 to You may have 20 alkoxyl groups. Examples of the group having a steroid structure include cholestane-3-yl group, cholestane-5-en-3-yl group, cholestan-24-en-3-yl group, and cholestane-5,24-diene-3-yl. Yl group, lanostane-3-yl group, and the like.
Examples of the diamine (3-1) in the present invention include 1,1-bis (4-((aminophenyl) methyl) phenyl) -4-butylcyclohexane and 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, the following formula (3-1-1)

(In formula (3-1-1), X ³ is a single bond, a methylene group, an alkylene group having 2 or 3 carbon atoms, ^* -O-, ^* -COO-, ^* -OCO-, ^* -X'-R. ^{7 -,} * ^{-R 7} -X'- or ^{* -X'-R 7 -X '-} ( where X' are ^each, + ^-O-, + -COO- or ⁺ -OCO- (where " “+” Represents that the bond with this is directed to the left in formula (3-1-1).) R ⁷ is an alkylene group having 2 or 3 carbon atoms, respectively. ”Is a bond with a diaminophenyl group.), H is an integer of 0 to 2, i is 0 or 1, and when h + i is 2 or more, R is a hydrogen atom and 1 carbon atom. -20 alkyl group or C1-C20 fluoroalkyl group, and when h + i is 0 or 1, R has a steroid structure. That group is a fluoroalkyl group of alkyl group or 4 to 20 carbon atoms having 4 to 20 carbon atoms.)
The compound etc. which are represented by these can be mentioned. The alkyl group and fluoroalkyl group in the above formula (3-1-1) are each preferably a straight chain group.

  As the diamine (3-1) in the present invention, a compound represented by the above formula (3-1-1) is preferable, and specific examples thereof include, for example, n-dodecanoxy-2,4-diaminobenzene, n-tetradecanoxy- 2,4-diaminobenzene, n-pentadecanoxy-2,4-diaminobenzene, n-hexadecanoxy-2,4-diaminobenzene, n-octadecanoxy-2,4-diaminobenzene, n-dodecanoxy-2,5-diaminobenzene N-tetradecanoxy-2,5-diaminobenzene, n-pentadecanoxy-2,5-diaminobenzene, n-hexadecanoxy-2,5-diaminobenzene, n-octadecanoxy-2,5-diaminobenzene, cholestanyloxy-3 , 5-Diaminobenzene, Cholestenyloxy-3,5-diamy Benzene, cholestanyloxy-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, the following formulas (3-1-1-1) to (3-1-1-5)

The compound represented by each of these can be mentioned.
A liquid crystal aligning agent containing a polyamic acid synthesized using a diamine containing the diamine (3-1) as described above in addition to the diamine (1) and the diamine (2) and a polyimide formed by dehydrating and ring-closing the polyamic acid, In particular, it is suitable for forming a liquid crystal alignment film of a VA liquid crystal display element.
The diamine (3-2) is a diamine other than the diamine (1), the diamine (2), and the diamine (3-1). For example, an aliphatic diamine, alicyclic diamine, aromatic diamine, diaminoorgano other than these diamines. It can be siloxane or the like. 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;

Examples of aromatic diamines include p-phenylenediamine, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenyl sulfide, 1,5-diaminonaphthalene, 2,2′-dimethyl-4,4′-diaminobiphenyl, 4,4′-diamino-2,2′-bis (trifluoromethyl) biphenyl, 2,7-diaminofluorene, 4,4′-diaminodiphenyl ether, 2,2-bis [4- (4-aminophenoxy) phenyl ] Propane, 9,9-bis (4-aminophenyl) fluorene, 2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane, 2,2-bis (4-aminophenyl) hexafluoropropane 4,4 ′-(p-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, 4- (4′-trifluoromethoxybenzoyloxy) cyclohexyl-3,5-diaminobenzoate and 4- (4′-trifluoro) And methyl acetoxyphenyl) cyclohexyl-3,5-aminobenzoate;
Examples of the diaminoorganosiloxane include 1,3-bis (3-aminopropyl) -tetramethyldisiloxane, respectively.
Diamines described in Patent Document 10 (Japanese Patent Application Laid-Open No. 2010-97188) can be used.

The diamine used for synthesizing the polyamic acid is preferably one containing 1 mol% or more of the diamine (1) as described above, more preferably 1 to 90 mol%, based on the total diamine. It is more preferable to contain 10 to 70 mol%, and particularly preferable to contain 20 to 50 mol%;
It is preferable that 5 mol% or more of diamine (2) is contained with respect to all diamines, more preferably 9 to 98 mol%, more preferably 20 to 80 mol%, and particularly preferably 40 to 70. It is preferable that it contains mol%. The ratio of the diamine (3-1) in the diamine used to synthesize the polyamic acid is preferably in the range of 40 mol% or less, and 0.1 to 40 mol% with respect to the total diamine. Is more preferable, it is more preferable that it is 1-30 mol%, and it is especially preferable that it is 10-20 mol%. The ratio of the diamine (3-2) in the diamine used for synthesizing the polyamic acid is preferably in the range of 30 mol% or less, more preferably 1 to 20 mol%, based on the total diamine. preferable.

<Molecular weight regulator>
When synthesizing the polyamic acid, a terminal-modified polymer may be synthesized using an appropriate molecular weight regulator together with the tetracarboxylic dianhydride and dimian as described above. By making the specific polymer into 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 the molecular weight regulator include acid monoanhydrides, monoamine compounds, monoisocyanate compounds, and the like. Specific examples of these acid monoanhydrides include maleic anhydride, phthalic anhydride, itaconic anhydride, n-decylsuccinic anhydride, n-dodecylsuccinic anhydride, n-tetradecylsuccinic acid. Nic acid anhydride, n-hexadecyl succinic acid anhydride, etc .;
Examples of monoamine compounds include aniline, cyclohexylamine, n-butylamine, n-pentylamine, n-hexylamine, n-heptylamine, and n-octylamine;
Examples of the monoisocyanate compound include phenyl isocyanate and naphthyl isocyanate.
The use ratio of the molecular weight regulator is preferably 20 parts by weight or less, and more preferably 10 parts by weight or less with respect to 100 parts by weight of the total of the tetracarboxylic dianhydride and diamine used.

<Synthesis of polyamic acid>
The ratio of the tetracarboxylic dianhydride and the diamine used in the polyamic acid synthesis reaction is 0.2 to 2 for the tetracarboxylic dianhydride acid anhydride group to 1 equivalent of the amino group of the diamine. The ratio which becomes an equivalent is preferable, More preferably, it is the ratio which becomes 0.3-1.2 equivalent.
The polyamic acid synthesis reaction is preferably carried out in an organic solvent, preferably at -20 ° C to 150 ° C, more preferably at 0-100 ° C, preferably 0.1-24 hours, more preferably 0.5-12 hours. Done.
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, N, N-dimethylacetamide, N, N-dimethylformamide, dimethyl sulfoxide, γ-butyrolactone, tetramethylurea as the aprotic polar solvent. Hexamethylphosphotriamide, etc .;
Examples of the phenol derivative include m-cresol, xylenol, halogenated phenol and the like;
Examples of the alcohol include methyl alcohol, ethyl alcohol, isopropyl alcohol, cyclohexanol, ethylene glycol, propylene glycol, 1,4-butanediol, triethylene glycol, and ethylene glycol monomethyl ether;
Examples of the ketone include acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone;

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

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

<Synthesis of polyimide>
The polyimide can be obtained by dehydrating and ring-closing the polyamic acid synthesized as described above to imidize.
The polyimide in the present invention may be a completely imidized product obtained by dehydrating and cyclizing all of the amic acid structure that the polyamic acid that is a precursor thereof has, or by dehydrating and cyclizing only a part of the amic acid structure, A partially imidized product in which a structure and an imide ring structure coexist may be used. The polyimide in the present invention preferably has an imidation ratio of 30 to 90%, more preferably 40 to 80%, and more preferably 50 to 70%. 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 if necessary. . Of these, the latter method is preferred.

In the method of adding a dehydrating agent and a dehydrating ring-closing catalyst to the polyamic acid solution, for example, an acid anhydride such as acetic anhydride, propionic anhydride, or trifluoroacetic anhydride can be used as the dehydrating agent. It is preferable that the usage-amount of a dehydrating agent shall be 0.01-20 mol with respect to 1 mol of the amic acid structure of a polyamic acid. As the dehydration ring closure catalyst, for example, tertiary amines such as pyridine, collidine, lutidine, and triethylamine can be used. It is preferable that the usage-amount of a dehydration ring-closing catalyst shall be 0.01-10 mol with respect to 1 mol of dehydrating agents to be used. Examples of the organic solvent used in the dehydration ring-closing reaction include the organic solvents exemplified as those used for the synthesis of polyamic acid. The reaction temperature of the dehydration ring closure reaction is preferably 0 to 180 ° C, more preferably 10 to 150 ° C. The reaction time is preferably 1.0 to 120 hours, more preferably 2.0 to 30 hours.
In this way, a reaction solution containing polyimide is obtained. This reaction solution may be used as it is for the preparation of the liquid crystal aligning agent, or may be used for the preparation of the liquid crystal aligning agent after removing the dehydrating agent and the dehydrating ring-closing catalyst from the reaction solution. It may be used for the preparation of a liquid crystal aligning agent or may be used for the preparation of a liquid crystal aligning agent after purifying the isolated polyimide. These purification operations can be performed according to known methods.

<Solution viscosity of polymer>
The polyamic acid obtained as described above and the polyimide formed by dehydrating and ring-closing the polyamic acid have a solution viscosity of 20 to 800 mPa · s when these are each made into a solution having a concentration of 10% by weight. It is more preferable that it has a solution viscosity of 30 to 500 mPa · s.
The solution viscosity (mPa · s) of the above polymer is E for a polymer solution having a concentration of 10% by weight prepared using a good solvent for the polymer (for example, γ-butyrolactone, N-methyl-2-pyrrolidone, etc.). It is a value measured at 25 ° C. using a mold rotational viscometer.

<Other ingredients>
The liquid crystal aligning agent of the present invention contains the polyamic acid as described above and a polyimide formed by dehydrating and ring-closing the polyamic acid as essential components, but further contains other components as long as the effects of the present invention are not diminished. May be.
Examples of such other components include other polymers, compounds having at least one epoxy group in the molecule (hereinafter referred to as “epoxy compound”), and functional silane compounds.

[Other polymers]
The other polymer is a polymer other than the polyamic acid as described above and a polyimide obtained by dehydrating and ring-closing the polyamic acid. For example, polyorganosiloxane, tetracarboxylic dianhydride and diamine (however, this diamine is a diamine). (1) and a diamine (2 does not contain at least one of diamines)) and a polyimide obtained by reacting the polyamic acid (hereinafter referred to as “other polyamic acid”) and dehydrating and ring-closing the polyamic acid. (Hereinafter referred to as “other polyimides”), polyamic acid esters, polyesters, polyamides, polysiloxanes, cellulose derivatives, polyacetals, polystyrene derivatives, poly (styrene-phenylmaleimide) derivatives, poly (meth) acrylates, and the like. it can. Among these, at least one selected from the group consisting of polyorganosiloxane, other polyamic acids, and other polyimides is preferable, and polyorganosiloxane is more preferable.

-Polyorganosiloxane-
Examples of the polyorganosiloxane include polyorganosiloxanes having an alkyl group having 4 to 40 carbon atoms, a fluoroalkyl group having 4 to 40 carbon atoms, a group having a structure in which two or more 6-membered rings are connected, or a group having a steroid structure. It is preferable that When the polyorganosiloxane has such a group, a liquid crystal alignment film formed from a polymer composition containing the group exhibits favorable liquid crystal alignment ability, which is preferable.
The polyorganosiloxane is more preferably a polyorganosiloxane having an epoxy group in addition to the above groups. Since the polyorganosiloxane has an epoxy group, the liquid crystal alignment film formed from the polymer composition containing the polyorganosiloxane has tough mechanical properties and is excellent in various performances such as heat resistance and light resistance. preferable.
Such polyorganosiloxane is, for example, a polyorgano having an epoxy group by hydrolytic condensation of a silane compound containing a silane compound having an epoxy group and a hydrolyzable group, preferably in the presence of an organic solvent, water and a catalyst. First, siloxane is synthesized, and then the polyorganosiloxane has an alkyl group having 4 to 40 carbon atoms, a fluoroalkyl group having 4 to 40 carbon atoms, a group having a structure in which two or more 6-membered rings are connected, or a steroid structure. It can be synthesized by reacting with a compound having a group and a carboxyl group (hereinafter referred to as “carboxylic acid (1)”).
The epoxy structure of a silane compound having an epoxy group and a hydrolyzable group may exist as a 1,2-epoxy structure in a 3-glycidyloxypropyl group or a 2- (3,4-epoxycyclohexyl) ethyl group. preferable.

Examples of the silane compound having an epoxy group and a hydrolyzable group include 3-glycidyloxypropyltrimethoxysilane, 3-glycidyloxypropyltriethoxysilane, 3-glycidyloxypropylmethyldimethoxysilane, and 3-glycol. Sidyloxypropylmethyldiethoxysilane, 3-glycidyloxypropyldimethylmethoxysilane, 3-glycidyloxypropyldimethylethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 2- (3,4- (Epoxycyclohexyl) ethyltriethoxysilane and the like, and one or more selected from these can be used.
The silane compound used for synthesizing the polyorganosiloxane having an epoxy group may be composed only of the silane compound having an epoxy group and a hydrolyzable group as described above, or in addition to the silane compound. Further, it may contain other silane compounds.
Examples of other silane compounds that can be used here include methyltrichlorosilane, methyltrimethoxysilane, methyltriethoxysilane, phenyltrichlorosilane, phenyltrimethoxysilane, phenyltriethoxysilane, methyldichlorosilane, and methyldimethoxysilane. , Methyldiethoxysilane, dimethyldichlorosilane, dimethyldimethoxysilane, dimethyldiethoxysilane, diphenyldichlorosilane, diphenyldimethoxysilane, diphenyldiethoxysilane, chlorodimethylsilane, methoxydimethylsilane, ethoxydimethylsilane, chlorotrimethylsilane, bromotrimethyl Silane, iodotrimethylsilane, methoxytrimethylsilane, ethoxytrimethylsilane, 3- (meth) acryloxypro Rutrichlorosilane, 3- (meth) acryloxypropyltrimethoxysilane, 3- (meth) acryloxypropyltriethoxysilane, vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, allyltrichlorosilane, allyltrimethoxysilane, An allyl triethoxysilane etc. can be mentioned and 1 or more types selected from these can be used.

The silane compound used for synthesizing the polyorganosiloxane having an epoxy group contains 5 mol% or more of the silane compound having an epoxy group and a hydrolyzable group as described above with respect to the total silane compound. It is preferable to contain 10 mol% or more.
Examples of the organic solvent that can be used for synthesizing the polyorganosiloxane having an epoxy group include hydrocarbons, ketones, esters, ethers, and alcohols.
Examples of the hydrocarbon include toluene and xylene;
Examples of the ketone include methyl ethyl ketone, methyl isobutyl ketone, methyl-n-amyl ketone, diethyl ketone, and cyclohexanone;
Examples of the ester include ethyl acetate, acetic acid-n-butyl, acetic acid-i-amyl, propylene glycol monomethyl ether acetate, 3-methoxybutyl acetate, and ethyl lactate;
Examples of the ether include ethylene glycol dimethyl ether, ethylene glycol diethyl ether, tetrahydrofuran, dioxane and the like;
Examples of the alcohol include 1-hexanol, 4-methyl-2-pentanol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono-n-propyl ether, ethylene glycol mono-n-butyl ether, propylene glycol monomethyl. Examples include ether, propylene glycol monoethyl ether, propylene glycol mono-n-propyl ether, and one or more selected from these can be used. Among these, it is preferable to select and use a water-insoluble one.
The amount of the organic solvent used is preferably 10 to 10,000 parts by weight and more preferably 50 to 1,000 parts by weight with respect to 100 parts by weight of the total silane compound.

The amount of water used when synthesizing the polyorganosiloxane having an epoxy group is preferably 0.5 to 100 mol, more preferably 1 to 30 mol, relative to a total of 1 mol of the silane compound.
As said catalyst, an acid, an alkali metal compound, an organic base, a titanium compound, a zirconium compound etc. can be used, for example, It is preferable to use an alkali metal compound or an organic base among these. By using an alkali metal compound or an organic base as a catalyst, formation of a three-dimensional structure is promoted, and a polyorganosiloxane having a low content of silanol groups is obtained. For this reason, since the condensation reaction between silanol groups can be suppressed even during the reaction with the carboxylic acid described later and after the liquid crystal aligning agent containing the product of the reaction, a liquid crystal aligning agent having excellent storage stability is obtained. It is preferable at the point which can do.
Examples of the alkali metal compound include sodium hydroxide, potassium hydroxide, sodium methoxide, potassium methoxide, sodium ethoxide, potassium ethoxide and the like.
Examples of the organic base include primary and secondary organic amines such as ethylamine, diethylamine, piperazine, piperidine, pyrrolidine, and pyrrole;
Tertiary organic amines such as triethylamine, tri-n-propylamine, tri-n-butylamine, pyridine, 4-dimethylaminopyridine, diazabicycloundecene;
Examples thereof include quaternary organic amines such as tetramethylammonium hydroxide. Among these organic bases, tertiary organic amines such as triethylamine, tri-n-propylamine, tri-n-butylamine, pyridine and 4-dimethylaminopyridine; quaternary organic amines such as tetramethylammonium hydroxide preferable.

As the catalyst, an organic base is particularly preferable. The amount of the organic base used varies depending on the reaction conditions such as the type of organic base and temperature, and should be set appropriately. For example, it is preferably 0.01 to 3 mol with respect to 1 mol of the silane compound in total. Yes, more preferably 0.05 to 1 mol.
Hydrolytic condensation reaction when synthesizing a polyorganosiloxane having an epoxy group is carried out by dissolving a silane compound and other silane compounds as required in an organic solvent, and mixing this solution with an organic base and water. It is preferably carried out by heating using a suitable heating device such as an oil bath.
In the hydrolysis condensation reaction, the heating temperature is preferably 130 ° C. or lower, more preferably 40 to 100 ° C., and preferably 0.5 to 12 hours, more preferably 1 to 8 hours. During the heating, the mixed solution may be stirred or may not be stirred, or the mixed solution may be placed under reflux.
After completion of the reaction, the organic solvent layer separated from the reaction mixture is preferably washed with water. In this washing, washing with water containing a small amount of salt, for example, an aqueous ammonium nitrate solution of about 0.2% by weight is preferred because the washing operation is facilitated. Washing is carried out until the aqueous layer after washing becomes neutral, and then the organic solvent layer is dried with an appropriate desiccant such as anhydrous calcium sulfate or molecular sieves as necessary, and then the solvent is removed to remove the solvent. A polyorganosiloxane having an epoxy group can be obtained.

The polyorganosiloxane having an epoxy group thus obtained is then reacted with the carboxylic acid (1), preferably in the presence of a catalyst and an organic solvent, to thereby obtain 4 carbon atoms derived from the carboxylic acid (1). A polyorganosiloxane having an alkyl group of ˜40, a fluoroalkyl group of 4 to 40 carbon atoms, a group having a structure in which two or more 6-membered rings are linked, or a group having a steroid structure can be obtained. Here, the polyorgano also having an epoxy group in addition to the above group by making the use ratio of the carboxylic acid (1) less than 1 mole with respect to 1 mole of the epoxy group of the polyorganosiloxane having an epoxy group. It can be siloxane.
Examples of the carboxylic acid (1) include the following formula (C)

(In formula (C), X ⁴ is a single bond, ^* —O—, ^* —COO— or ^* —OCO— (where the bond marked with “*” is on the R ′ side), and R ^I is a cyclohexylene group or a phenylene group, f1 is 1 or 2, provided that when f1 is 2, two R ^I may be the same or different from each other, and f2 is 0 or 1 Is;
X ⁵ is ^* —O—, ^* —COO— or ^* —OCO— (where the bond with “*” is on the R ′ side), and R ^II is a methylene group or carbon A (di) alkylmethylene group having an alkyl group of 1 to 4, f3 is an integer of 0 to 3, provided that when f3 is 2 or 3, a plurality of ^RIIs may be the same or different from each other F4 is 0 or 1;
When f1 is 2 or more and f2 is 1, R ′ is a hydrogen atom, an alkyl group having 1 to 40 carbon atoms or a fluoroalkyl group having 1 to 40 carbon atoms, and f1 is 1 or f2 is 0 R ′ is a group having a steroid structure, an alkyl group having 4 to 40 carbon atoms, or a fluoroalkyl group having 4 to 40 carbon atoms. )
The compound represented by these can be mentioned.

The alkyl group having 1 to 40 carbon atoms and the alkyl group having 4 to 40 carbon atoms of R ′ are each preferably a linear alkyl group having 5 to 20 carbon atoms. Specific examples thereof include, for example, n-pentyl. Group, n-hexyl group, n-octyl group, n-decyl group, n-dodecyl group, n-hexadecyl group, stearyl group and the like. The fluoroalkyl group having 1 to 40 carbon atoms and the fluoroalkyl group having 4 to 40 carbon atoms are each preferably a straight-chain fluoroalkyl group having 4 to 20 carbon atoms. , 4-trifluorobutyl group, 5,5,5-trifluoropentyl group, 7,7,7-trifluoroheptyl group, 11,11,11-trifluoroundecyl group, 4,4,5,5 A 5-pentafluoropentyl group, 5,5,6,6,6-pentafluorohexyl group, 9,9,10,10,10-pentafluorodecyl group and the like can be mentioned. The group having a steroid skeleton is preferably a hydrocarbon group having 17 to 51 carbon atoms having a steroid skeleton, and specific examples thereof include a 3-cholestanyl group, a 3-cholestenyl group, a 3-lanostanil group, and the like. Can do.
The cyclohexylene group and phenylene group of R ¹ in the above formula (C) are preferably 1,4-cyclohexylene group and 1,4-phenylene group, respectively. Examples of the divalent group represented by — (R ^I ) _f1 — in the above formula (C) include the case where f1 is 1, for example, 1,4-phenylene group, 1,2-cyclohexylene group and the like. ;
In the case where f1 is 2, for example, 4,4′-biphenylene group, 4,4′-bicyclohexylene group, the following formulas (R ^I- 1) and (R ^I- 2)

(In the above formula, the bond marked with “*” is the R ′ side.)
And groups represented by each of the above.
In the above formula (C), f3 is preferably 2 or 3.
Specific examples of the carboxylic acid (1) include, for example, 4-octyloxybenzoic acid, 4-cyclohexylbenzoic acid, and the following formulas (C-1) to (C-5).

The compound represented by each of these can be mentioned, It is preferable to use 1 or more types selected from these.
The use ratio of the carboxylic acid having the structure represented by the above formula (I) is preferably less than 1 mol with respect to 1 mol of the epoxy group of the polyorganosiloxane having an epoxy group, More preferably, it is more preferably 10 to 70 mol.
As said catalyst, a well-known compound can be used as what is called a hardening accelerator which accelerates | stimulates reaction with an organic base or an epoxy compound, and an acid anhydride.
Examples of the organic base include primary and secondary organic amines such as ethylamine, diethylamine, piperazine, piperidine, pyrrolidine, and pyrrole;
Tertiary organic amines such as triethylamine, tri-n-propylamine, tri-n-butylamine, pyridine, 4-dimethylaminopyridine, diazabicycloundecene;
A quaternary organic amine such as tetramethylammonium hydroxide can be used. Of these organic bases, tertiary organic amines such as triethylamine, tri-n-propylamine, tri-n-butylamine, pyridine, 4-dimethylaminopyridine;
Quaternary organic amines such as tetramethylammonium hydroxide are preferred.

Examples of the curing accelerator include tertiary amines, imidazole compounds, organic phosphorus compounds, quaternary phosphonium salts, diazabicycloalkenes, organometallic compounds, quaternary ammonium salts, boron compounds, metal halogen compounds, and the like. In addition, it is possible to use those known as latent curing accelerators.
The catalyst is used in an amount of preferably 100 parts by weight or less, more preferably 0.01 to 100 parts by weight, and still more preferably 0.1 to 20 parts by weight with respect to 100 parts by weight of the polyorganosiloxane having an epoxy group. .
Examples of the organic solvent include hydrocarbons, ethers, esters, ketones, amides, alcohols, and the like. Of these, ethers, esters or ketones are preferred from the viewpoints of solubility of raw materials and products and ease of purification of the products. The solvent is used in such a ratio that the solid content concentration (the ratio of the weight of components other than the solvent in the reaction solution to the total weight of the solution) is preferably 0.1% by weight or more, more preferably 5 to 50% by weight. Is done.
The reaction temperature is preferably 0 to 200 ° C, more preferably 50 to 150 ° C. The reaction time is preferably 0.1 to 50 hours, more preferably 0.5 to 20 hours.
For the polyorganosiloxane as described above, the polystyrene-reduced weight average molecular weight (Mw) measured by gel permeation chromatography is preferably 1,000 to 50,000, more preferably 1,000 to 10,000. is there.

-Epoxy compound-
The epoxy compound is a compound having at least one epoxy group in the molecule, but those corresponding to the polyorganosiloxane or the functional silane compound described later are excluded.
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, 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′-diaminodiphe Rumetan, N, N-diglycidyl - benzylamine, N, N-diglycidyl - aminomethyl cyclohexane, N, N-diglycidyl - cyclohexyl amine may be mentioned as preferred.
The compounding ratio of these epoxy compounds is the sum of the polymers (tetracarboxylic dianhydride and the diamine containing a compound represented by the above formula (A1) and a compound having a carboxyl group and two amino groups). And the total of at least one polymer selected from the group consisting of polyimides obtained by dehydrating and ring-closing the polyamic acid, and other polymers. The same shall apply hereinafter.) 100 parts by weight The amount is preferably 30 parts by weight or less, more preferably 20 parts by weight or less, still more preferably 10 parts by weight or less, and particularly preferably less than 1 part by weight.

-Functional silane compounds-
Examples of the functional silane compound include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 2-aminopropyltrimethoxysilane, 2-aminopropyltriethoxysilane, N- (2-aminoethyl)- 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-ureidopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, N-ethoxycarbonyl-3-aminopropyl Trimethoxysilane, N-ethoxycarbonyl-3-aminopropyltriethoxysilane, N-triethoxysilylpropyltriethylenetriamine, N-trimethoxysilylpropyltriethylenetriamine, 10-trimethoxysilyl-1,4 7-triazadecane, 10-triethoxysilyl-1,4,7-triazadecane, 9-trimethoxysilyl-3,6-diazanonyl acetate, 9-triethoxysilyl-3,6-diazanonyl acetate, 9- Methyl 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-glycidoxyethyltrimethoxysilane, 2-glycidoxyethyltriethoxysilane, 3 Glycidoxypropyltrimethoxysilane, and 3-glycidoxypropyl triethoxy silane and the like.
The blending ratio of these functional silane compounds is preferably 2 parts by weight or less, more preferably 0.02 to 0.2 parts by weight with respect to 100 parts by weight of the total amount of the polymer.

<Liquid crystal aligning agent>
The liquid crystal aligning agent of the present invention preferably includes at least one polymer selected from the group consisting of the polyamic acid and the imidized polymer as described above, and other components optionally blended as necessary. It is constituted by being dissolved and contained in an organic solvent.
Examples of the organic solvent that can be used in the liquid crystal aligning agent of the present invention include N-methyl-2-pyrrolidone, γ-butyrolactone, γ-butyrolactam, N, N-dimethylformamide, N, N-dimethylacetamide, 4-hydroxy-4. -Methyl-2-pentanone, ethylene glycol monomethyl ether, butyl lactate, butyl acetate, methyl methoxypropionate, ethyl ethoxypropionate, ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol-n-propyl ether, Ethylene glycol-i-propyl ether, ethylene glycol-n-butyl ether (butyl cellosolve), ethylene glycol dimethyl ether, ethylene glycol ethyl ether acetate, diethylene glycol dimethyl Ether, diethylene glycol diethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diisobutyl ketone, isoamyl propionate, isoamyl isobutyrate, diisopentyl ether, ethylene carbonate, propylene carbonate, etc. 1 or more types selected from these can be used.

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, when heated, a coating film that becomes a liquid crystal aligning film is formed, but the solid content concentration is less than 1% by weight. In this case, the film thickness of the coating film becomes 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. Thus, a good liquid crystal alignment film cannot be obtained, and the viscosity of the liquid crystal aligning agent increases, resulting in poor coating properties.
The particularly preferable solid content concentration range varies depending on the method used when applying the liquid crystal aligning agent 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 to 50 degreeC, More preferably, it is 20 to 30 degreeC.

<Liquid crystal display element>
The liquid crystal display element of the present invention comprises a liquid crystal alignment film formed from the liquid crystal aligning agent of the present invention as described above.
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.

(1) 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 formed on each transparent conductive film forming surface. The liquid crystal aligning agent of the invention is preferably applied by an offset printing method, a spin coating method or an ink jet printing method, respectively, and then each coated surface is heated to form a coating film. The liquid crystal aligning agent of the present invention is preferable because the effect of the present invention, which is excellent in printability when used in an offset printing method, is exhibited to the maximum extent.
Here, as the substrate, for example, a glass such as float glass or soda glass; a transparent substrate made of a plastic such as polyethylene terephthalate, polybutylene terephthalate, polyethersulfone, polycarbonate, or poly (alicyclic olefin) can be used. As a transparent conductive film provided on one surface of the substrate, an NESA film (registered trademark of PPG, USA) made of tin oxide (SnO ₂ ), an ITO film made of indium oxide-tin oxide (In ₂ O ₃ —SnO ₂ ), etc. In order to obtain a patterned transparent conductive film which can be used, for example, a method of forming a pattern by photo-etching after forming a transparent conductive film without a pattern, a mask having a desired pattern when forming the transparent conductive film The method using can be used. When applying the liquid crystal aligning agent, in order to further improve the adhesion between the substrate surface and the transparent conductive film and the coating film, a functional silane compound or functional titanium is formed on the surface of the substrate surface on which the coating film is to be formed. You may give the pretreatment which apply | coats a compound etc. previously.
After 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 a polyamic acid 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) On the other hand, when manufacturing an IPS type liquid crystal display element, the conductive film forming surface of the substrate provided with the comb-shaped transparent conductive film and the counter substrate provided with no conductive film The liquid crystal aligning agent of this invention is apply | coated to one surface, respectively, Then, a coating film is formed by heating each application surface.
The material of the substrate and transparent conductive film, the patterning method of the transparent conductive film, the pretreatment of the substrate, the coating method of the liquid crystal aligning agent, and the heating method after coating used in this case are the same as in (1-1) above.
The preferable film thickness of the coating film to be formed is the same as (1-1) above.

(2) When the liquid crystal display element manufactured by the method of the present invention is a VA liquid crystal display element, the coating film formed as described above can be used as a liquid crystal alignment film as it is. If desired, it may be used after the following rubbing treatment.
On the other hand, when manufacturing a liquid crystal display element other than the VA type, a rubbing treatment is performed on the coating film formed as described above to obtain a liquid crystal alignment film.
The rubbing treatment can be performed by rubbing the coating film surface formed as described above with a roll wound with a cloth made of fibers such as nylon, rayon, and cotton 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.
Further, for the liquid crystal alignment film formed as described above, for example, a liquid crystal as shown in Patent Document 7 (JP-A-6-222366) and Patent Document 8 (JP-A-6-281937). A process of changing the pretilt angle of a partial region of the liquid crystal alignment film by irradiating a part of the alignment film with ultraviolet rays, or a liquid crystal alignment as disclosed in Patent Document 9 (Japanese Patent Laid-Open No. 5-107544) A resist film is formed on a part of the film surface, then the rubbing process is performed in a direction different from the previous rubbing process, and then the resist film is removed so that the liquid crystal alignment film has different liquid crystal alignment capabilities in each region. It is possible to improve the visual field characteristics of the liquid crystal display element obtained by the above.
The liquid crystal alignment film of the present invention can also be suitably used for a PSA (Polymer Sustained Alignment) type liquid crystal display element.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. The solution viscosity of the polymer solution and the imidization ratio of the polyimide in the synthesis examples were measured by the following methods, respectively.
[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 each polymer solution specified in the synthesis example.
[Imidation rate of polyimide]
The polyimide solution was poured into pure water, and the resulting precipitate was sufficiently dried under reduced pressure at room temperature, then dissolved in deuterated dimethyl sulfoxide, and ¹ H-NMR was measured at room temperature using tetramethylsilane as a reference substance. From the obtained ¹ H-NMR spectrum, the imidization ratio was determined by the formula shown by the following formula (1).
Imidation rate (%) = (1-A ¹ / A ² × α) × 100 (1)
(In Formula (1), ^{A 1} is the peak area derived from proton of NH group appearing in the vicinity of the chemical shift 10 ppm,
A ² is the peak area derived from other protons,
α is the number ratio of other protons to one NH proton in the polymer precursor (polyamic acid). )

<Polyimide synthesis example>
Synthesis Example J-1
220 g (1.0 mol) of 2,3,5-tricarboxycyclopentylacetic acid dianhydride as tetracarboxylic dianhydride and 49 g (0.1 mol) of 3- (2,4-diaminophenoxy) cholestane as diamine, 1 53 g (0.2 mol) of-(4-aminophenyl) -2,3-dihydro-1,3,3-trimethyl-1H-indene-5-amine (compound represented by the above formula (A1-1)) 54 g (0.2 mol) of the compound represented by the above formula (A2-2-1) and 99 g (0.5 mol) of 4,4′-diaminodiphenylmethane were mixed with N-methyl-2-pyrrolidone (NMP) 1, It melt | dissolved in 900g and reacted at 60 degreeC for 6 hours, and obtained the solution containing a polyamic acid. The solution viscosity measured by separating a small amount of the obtained polyamic acid solution was about 1,400 mPa · s.
Next, 2,400 g of NMP was added to the obtained polyamic acid solution, 120 g of pyridine (corresponding to 1.5 mol per 1 mol of the amic acid unit of the polyamic acid) and 153 g of acetic anhydride (of the polyamic acid). This is equivalent to 1.5 moles per mole of the amic acid unit possessed.) And a dehydration ring closure reaction was carried out 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 shall apply hereinafter) to obtain an imidation ratio of about 61. A solution containing about 15% by weight of polyimide (I-1) was obtained.

Synthesis Examples J-2 to J-17
In Synthesis Example J-1, the types and amounts of tetracarboxylic dianhydride and diamine used as raw material monomers and the amounts of pyridine and acetic anhydride used in the dehydration ring-closing reaction (relative to the number of moles of amic acid units possessed by each polyamic acid) Polyimides (I-2) to (I-10) and (II-1) to (II) in the same manner as in Synthesis Example J-1 except that the molar amount is as described in Table 1. A solution containing 15% by weight of -7) was obtained.
Table 1 shows the viscosity of the polyamic acid solution and the imidization ratio of the obtained polyimide in the process of synthesizing these polyimide solutions.
Synthesis examples J-11 to J-17 are comparative synthesis examples.

In Table 1, the abbreviations of the raw material monomers have the following meanings, respectively, and “-” indicates that the raw material monomer corresponding to the column was not used.
[Tetracarboxylic dianhydride]
T-1: 2,3,5-tricarboxycyclopentyl acetic acid dianhydride T-2: pyromellitic dianhydride [diamine]
-Diamine (1)-
D-1: 1- (4-Aminophenyl) -2,3-dihydro-1,3,3-trimethyl-1H-indene-5-amine (compound represented by the above formula (A1-1))
-Diamine (2)-
D-2-1: 2,2′-dicarboxybenzidine (compound represented by the above formula (A2-2-1))
D-3: 3,5-bis (4-aminophenoxy) benzoic acid D-4: 3,5-diaminobenzoic acid-diamine (3-1)-
D-5: 3- (2,4-diaminophenoxy) cholestane D-6: 3- (3,5-diaminobenzoyloxy) cholestane D-7: 4- (2- (4- (4-pentylcyclohexyl) phenoxy ) Ethoxy) benzene-1,3-diamine (compound represented by the above formula (3-1-1-4))
D-8: 3,5-Diaminobenzoic acid 4- (2- (4-(-pentylcyclohexyl) phenoxy) ethyl (compound represented by the above formula (3-1-1-5))
-Diamine (3-2)-
D-9: p-phenylenediamine D-10: 4,4'-diaminodiphenylmethane

<Synthesis example of polyorgangaon siloxane>
Synthesis Example P-1
[Synthesis of polyorganosiloxane having epoxy group]
In a reaction vessel equipped with a stirrer, thermometer, dropping funnel and reflux condenser, 99 g of 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane as a silane compound, 500 g of methyl isobutyl ketone as a solvent and 10 g of triethylamine as a catalyst. Charged and mixed at room temperature. Next, 100 g of deionized water was dropped from the dropping funnel over 30 minutes, and the reaction was performed at 80 ° C. for 6 hours while stirring under reflux. After completion of the reaction, the organic layer is taken out and washed with a 0.2 wt% ammonium nitrate aqueous solution until the water after washing becomes neutral, and then the solvent and water are distilled off under reduced pressure, whereby a polyorgano having an epoxy group is obtained. Siloxane was obtained as a viscous transparent liquid.
When this hydrolyzed condensate was subjected to ¹ H-NMR analysis, a peak based on an epoxy group was obtained in the vicinity of chemical shift (δ) = 3.2 ppm according to the theoretical intensity, and a side reaction of the epoxy group occurred during the reaction. It was confirmed that this was not happening.
[Reaction of Polyorganosiloxane Having Epoxy Group with Carboxylic Acid (1)]
In a 200 mL three-necked flask, the polyorganosiloxane having the epoxy group obtained above, 30 g of methyl isobutyl ketone as the solvent, 25 g of 4-octyloxybenzoic acid as the carboxylic acid (1) (the epoxy group of the polyorganosiloxane having the epoxy group) And 0.10 g of UCAT 18X (trade name, an epoxy compound curing accelerator manufactured by San Apro Co., Ltd.) as a catalyst and stirring at 100 ° C. for 48 hours. Reaction was performed. After completion of the reaction, the organic layer obtained by adding ethyl acetate to the reaction mixture was washed with water three times, dried using magnesium sulfate, and then the solvent was distilled off to obtain polyorganosiloxane (S-1). . About this S-1, the weight average molecular weight (Mw) in polystyrene conversion measured by gel permeation chromatography was 6,300.

Synthesis Examples P-2 to P-10
Synthesis of polyorganosiloxane having an epoxy group and synthesis of polyorganosiloxane in the same manner as in Synthesis Example P-1, except that the type and amount of carboxylic acid (1) described in Table 2 were used in Synthesis Example P-1. And polycarboxylic acid (1) were reacted to obtain polyorganosiloxanes (S-2) to (S-10), respectively. Table 2 shows the Mw of these polyorganosiloxanes.

The abbreviations of carboxylic acid (1) in Table 2 have the following meanings, respectively, and the amount (molar ratio) of carboxylic acid (1) used is the molar ratio (%) to the epoxy groups of the polyorganosiloxane having epoxy groups. It is.
1-1: 4-Octyloxybenzoic acid 1-2: Compound represented by formula (C-1) 1-3: Compound represented by formula (C-2) 1-4: Formula (C- 3) Compound represented by 1-5: Compound represented by the above formula (C-4) 1-6: Compound represented by the above formula (C-5)

<Preparation and evaluation of liquid crystal aligning agent>
Example 1
(I) Preparation of liquid crystal aligning agent N-methyl-2-pyrrolidone (NMP) and butyl cellosolve (BC) are added to a solution containing the polyimide (I-1) obtained in Synthesis Example J-1 as a polyimide, and the above 5 parts by weight of polyorganosiloxane (S-3) obtained in Synthesis Example P-3 is added to 100 parts by weight of polyimide (I-1) and sufficiently stirred, and the solvent composition is NMP: BC = 48: 52 ( (Weight ratio) and a solid content concentration of 6.0% by weight. A liquid crystal aligning agent was prepared by filtering this solution using a filter having a pore diameter of 1 μm.
(II) Formation and Evaluation of Coating Film (1) Evaluation of Printability The liquid crystal aligning agent prepared above is transparent made of an ITO film using an offset type liquid crystal alignment film printer (Nissha Printing Co., Ltd.). It is applied to the transparent electrode surface of a glass substrate with electrodes, heated for 1 minute on a hot plate at 80 ° C. (pre-baked), removed the solvent, then heated on a hot plate at 200 ° C. for 10 minutes (post-baked), A coating film having an average film thickness of 600 mm measured with a stylus-type film thickness meter (manufactured by KLA Tencor) was formed. When this coating film was observed with a microscope with a magnification of 20 times to check for the presence of printing unevenness and pinholes, neither printing unevenness nor pinholes were observed, and the printability was “good”.
(2) Evaluation of film thickness uniformity of coating film About the coating film formed above, the film thickness at the center of the substrate and the center of 15 mm from the outer edge of the substrate using a stylus-type film thickness meter (manufactured by KLA Tencor) The film thickness at the position near the film was measured. When the film thickness difference between the two was 20 mm or less, the film thickness uniformity was evaluated as “good”, and when the film thickness difference exceeded 20 mm was evaluated as film thickness uniformity “bad”, the film uniformity was good.
(3) Evaluation of water resistance of coating film For the substrate on which the coating film was formed as described above, a “DVA-36LH” automatic ellipsometer manufactured by Mizoji Optical Industry Co., Ltd. was used, and a He—Ne laser (632.8 nm) as a light source ) Was used to measure the film thickness at an incident angle φ = 70 °.
Next, the substrate was stored in a constant temperature and humidity chamber at a relative humidity of 50% and 25 ° C. for 18 hours to absorb moisture. Thereafter, the film thickness was measured again in the same manner, and the change rate of the average film thickness before and after moisture absorption was calculated. The following formula (2)

Was used. The rate of change of this coating film was 0.4%.
Here, when this rate of change is less than 0.5%, the water resistance is "excellent", and when it is 0.5 to 1.5%, the water resistance is "good", 1.5% In the case of exceeding the water resistance, it can be determined that the water resistance is “poor”.
(4) Evaluation of peelability of coating film Using the liquid crystal aligning agent prepared above, a 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.) After coating, the film was heated at 120 ° C. for 3 minutes on a hot plate and then heated in a clean oven at 230 ° C. for 30 minutes, and the average film thickness measured by a stylus-type film thickness meter (manufactured by KLA Tencor) was 600 mm. A coating film was formed.
Next, the N-methyl-2-pyrrolidone solution was adjusted to a liquid temperature of 25 ° C., and the substrate on which the coating film was formed was immersed in the substrate with the immersion time as a variable amount. Next, after the substrate was washed with acetone, acetone was removed by air blowing, and the film thickness was measured again with a stylus thickness meter in the same manner as described above, and the film thickness after immersion was less than 10% before immersion. The soaking time was examined.
When this time is 10 seconds or less, the peelability is “excellent”, when 10 seconds is exceeded and less than 10 minutes, the peelability is “good”, and when it is 10 minutes or more, the peelability is “bad” As a result of evaluation, the peelability of this coating film was “good”.

(II) Manufacture and Evaluation of Liquid Crystal Cell (1) Manufacture of Liquid Crystal Cell Glass with transparent electrode made of ITO film using liquid crystal aligning agent prepared above using liquid crystal alignment film printer (Nissha Printing Co., Ltd.) After coating on the transparent electrode surface of the substrate and heating (pre-baking) on a hot plate at 80 ° C. for 1 minute to remove the solvent, heating (post-baking) on a hot plate at 200 ° C. for 10 minutes to obtain an average film thickness A 600-mm coating film was formed to obtain a pair (two) of substrates having a liquid crystal alignment film.
Next, an epoxy resin adhesive containing aluminum oxide spheres having a diameter of 5.5 μm was applied to the outer edge of the surface having the liquid crystal alignment film for one of the pair of substrates. Next, the pair of substrates was superposed and pressure-bonded so that the liquid crystal alignment film surfaces face each other, and the adhesive was cured. Thereafter, a nematic liquid crystal (MLC-6221, manufactured by Merck & Co., Inc.) is filled between the pair of substrates from the liquid crystal injection port, and then the liquid crystal injection port is sealed with an acrylic photo-curing adhesive to produce a liquid crystal cell. did.
(2) Evaluation of heat-resistant stability About the liquid crystal cell manufactured above, a rectangular wave of 30 Hz and 3.0 V on which AC 6.0 V (peak-peak) was superimposed was applied at an environmental temperature of 70 ° C. for 500 hours. When the cell after 500 hours passed was visually observed by sandwiching it between two polarizing plates with the polarization direction shifted by 90 °, if no display defect was observed, the heat stability was “good” and the display defect was observed. As a result, the heat stability of this liquid crystal cell was evaluated as “good”.
(3) Measurement of voltage holding ratio After a voltage of 5 V was applied to a liquid crystal cell manufactured in the same manner as described above for 60 microseconds with a span of 167 milliseconds, the voltage holding ratio after 167 milliseconds from the release of application. As a result, the voltage holding ratio of this liquid crystal cell was 97%. Here, “VHR-1” manufactured by Toyo Corporation was used as the measuring device.
When the voltage holding ratio is 96% or more, the voltage holding ratio is “excellent”. When the voltage holding ratio is 94% or more and less than 96%, the voltage holding ratio is “good”, and when the voltage holding ratio is less than 94%. It can be determined that the voltage holding ratio is “bad”.

Examples 2-11 and Comparative Examples 1-4
A liquid crystal aligning agent was prepared and evaluated in the same manner as in Example 1 except that the types and amounts of the polyimide and polyorganosiloxane used were as shown in Table 3, respectively. In Example 3, no polyorganosiloxane was used.
The evaluation results are shown in Table 3.
In Comparative Examples 2 and 4, since cocoon-skinned printing unevenness was observed, it was determined that the printability was “bad”.
Comparative Example 5
N-methyl-2-pyrrolidone (NMP) and butyl cellosolve (BC) were added to a solution containing polyimide (II-5) obtained in Synthesis Example J-15 as a polyimide, and further obtained in Synthesis Example P-7. After 5 parts by weight of polyorganosiloxane (S-7) is added to 100 parts by weight of polyimide (II-5) and sufficiently stirred, EP-1 listed in Table 3 is further added to polyimide (II-5) as an epoxy compound. ) 5 parts by weight with respect to 100 parts by weight and sufficiently stirred to obtain a solution having a solvent composition of NMP: BC = 48: 52 (weight ratio) and a solid content concentration of 6.0% by weight. Except that the liquid crystal aligning agent was prepared by filtering this solution using a filter having a pore diameter of 1 μm, the coating film was formed and evaluated, and the liquid crystal cell was manufactured and evaluated in the same manner as in Example 1 above.
Comparative Examples 6 and 7
A liquid crystal aligning agent was prepared and evaluated in the same manner as in Comparative Example 5 except that the types and amounts of the polyimide, polyorganosiloxane, and epoxy compound used were as shown in Table 3, respectively.
The evaluation results are shown in Table 3.

In addition, the abbreviation of the epoxy compound in Table 3 has the following meaning, respectively.
EP-1: N, N, N ′, N′-tetraglycidyl-4,4′-diaminodiphenylmethane EP-2: N, N, N ′, N′-tetraglycidyl-m-xylenediamine

Claims (6)

A liquid crystal aligning agent comprising a polyamic acid obtained by reacting a tetracarboxylic dianhydride and a diamine, and at least one polymer selected from the group consisting of polyimides formed by dehydrating and ring-closing the polyamic acid,
The diamine is represented by the following formula (A1)

(In Formula (A1), R ¹ is an alkyl group having 1 to 6 carbon atoms;
R ² is each an alkyl group having 1 to 6 carbon atoms, a halogen atom, a cyano group, or a hydroxyl group:
X ¹ is a single bond, a methylene group, an alkylene group having 2 to 6 carbon atoms, a phenylene group or a cyclohexylene group, provided that the alkylene group may be interrupted by an ether bond or an ester bond. The phenylene group and the cyclohexylene group may each be substituted by an alkyl group having 1 to 4 carbon atoms, an alkylene group having 1 to 4 carbon atoms, a hydroxyl group, a halogen atom or a cyano group;
a is an integer from 0 to 5;
b is an integer from 0 to 4;
c is an integer of 0-3. )
The liquid crystal aligning agent characterized by including the compound represented by these, and the compound which has a carboxyl group and two amino groups.   The tetracarboxylic dianhydride is 2,3,5-tricarboxycyclopentylacetic acid dianhydride, 3,5,6-tricarboxy-2-carboxymethylnorbornane-2: 3,5: 6-dianhydride and 2. The composition according to claim 1, comprising at least one selected from the group consisting of 2,4,6,8-tetracarboxybicyclo [3.3.0] octane-2: 4,6: 8-dianhydride. Liquid crystal aligning agent.   The diamine further includes a diamine having an alkyl group having 4 to 20 carbon atoms, an alkoxyl group having 4 to 20 carbon atoms, a group having a structure in which two or more 6-membered rings are connected, or a group having a steroid structure. Item 3. The liquid crystal aligning agent according to Item 1 or 2.   The liquid crystal aligning agent as described in any one of Claims 1-3 which further contains polyorganosiloxane.   A liquid crystal alignment film formed from the liquid crystal aligning agent according to claim 1.   A liquid crystal display element comprising the liquid crystal alignment film according to claim 5.