JP2015007745A - Liquid crystal aligning agent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal aligning agent having excellent photo-aligning property and a voltage retention rate and giving excellent contrast and afterimage characteristics.SOLUTION: The liquid crystal aligning agent comprises at least one polymer selected from a polyamic acid having a structure expressed by formula (1) shown below as a main chain and an imidized polymer of the polyamic acid. In the formula (1), two of X each independently represent a divalent saturated aliphatic group or a divalent unsaturated aliphatic group having 2 to 10 carbon atoms; two of Y each independently represent a single bond, an oxygen atom, a sulfur atom, an ester bond or a thioester bond; R represents a methylene group or an alkylene group having 2 to 12 carbon atoms which may be interrupted by an oxygen atom; and '*' represents a bond.

Description

  The present invention relates to a liquid crystal aligning agent.

In liquid crystal display elements widely used in televisions, mobile devices, various monitors, and the like, a liquid crystal alignment film is used to align liquid crystal molecules in a liquid crystal cell. Conventionally known methods for imparting liquid crystal alignment capability to this liquid crystal alignment film include a method of rubbing an organic film, a method of obliquely depositing silicon oxide, and a method of forming a monomolecular film having a long chain alkyl group. ing.
In recent years, the photo-alignment method has been actively studied because it can achieve uniform liquid crystal alignment without generating static electricity and dust, and also enables precise control of the liquid crystal alignment direction ( Patent Documents 1 to 3).
However, a liquid crystal alignment film formed by a photo-alignment method using a conventionally known liquid crystal alignment film material has a trade-off between obtaining a high contrast and realizing good afterimage characteristics. It was not possible to make the characteristics of the sufficiently high. For this reason, it has not been possible to satisfy the recent demands for high-definition image display and advanced video playback display.

JP-A-6-287453 JP 2003-307736 A JP-A-9-297313 JP 2010-97188 A

The present invention has been made in order to overcome the above-described current situation.
Accordingly, an object of the present invention is to provide a liquid crystal alignment film that exhibits good liquid crystal alignment properties by the photo-alignment method and is excellent in various characteristics such as electrical characteristics, and in particular, has both high contrast and good afterimage characteristics. It is to provide an alignment agent.

According to the present invention, the above objects and advantages of the present invention are:
Achieved by a liquid crystal aligning agent comprising at least one polymer selected from the group consisting of a polyamic acid having a structure represented by the following formula (1) in the main chain and an imidized polymer thereof Is done.

(In formula (1), two X's are each independently an oxygen atom, a sulfur atom, an ester bond, a thioester bond, an amide bond, -NH-, -C (= O)-, or a carbon number of 1-10. A divalent saturated aliphatic group or a divalent unsaturated aliphatic group having 2 to 10 carbon atoms;
Two Y's are each independently a single bond, oxygen atom, sulfur atom, ester bond or thioester bond;
R is a methylene group or an alkylene group having 2 to 12 carbon atoms which may be interrupted by an oxygen atom; and “*” represents a bond. )

  The liquid crystal aligning agent of this invention can form the liquid crystal aligning film which has favorable liquid crystal aligning property by the photo-alignment method. Since the liquid crystal alignment film formed from the liquid crystal aligning agent of the present invention is excellent in electrical characteristics represented by voltage holding ratio and has both high contrast and good afterimage characteristics (burn-in characteristics), the liquid crystal alignment film The liquid crystal display element having the above can be suitably applied to various applications.

Examples of the use of a liquid crystal display device comprising a liquid crystal alignment film formed from the liquid crystal alignment film of the present invention are as follows:
Televisions, portable games, word processors, notebook computers, car navigation systems, camcorders, personal digital assistants, digital cameras, mobile phones, various monitors, etc.

Explanatory drawing which shows the pattern of the electrode used for the liquid crystal display element for evaluating an afterimage characteristic.

As described above, the liquid crystal aligning agent of the present invention is at least one polymer selected from the group consisting of a polyamic acid having a structure represented by the above formula (1) in the main chain and an imidized polymer thereof (hereinafter referred to as the following). , "Specific polymer").
Here, the main chain of the polymer refers to a “trunk” portion composed of the longest chain of atoms in the polymer. The main chain is allowed to contain a ring structure. In this case, the entire ring structure is present in the main chain. Having the structure represented by the above formula (1) in the main chain means that this structure constitutes a part of the main chain. The requirement of the specific polymer in the present invention is that the structure represented by the above formula (1) exists in the main chain, but the structure is a part other than the main chain, for example, a side chain (the “stem of the polymer” It is not forbidden to exist in a superimposed manner in a portion branched from “”.
When X or Y in the above formula (1) is an ester bond or a thioester bond, and when X is an amide bond, the bonding direction may be either.
As a C1-C10 bivalent saturated aliphatic group in X, a methylene group, a 2, 2-propylene group, a C2-C10 alkylene group etc. can be mentioned, for example. The alkylene group preferably has 2 to 4 carbon atoms, and more preferably 2 carbon atoms. The divalent unsaturated aliphatic group having 2 to 10 carbon atoms in X is preferably an alka (poly) enylene group having 2 to 10 carbon atoms. The carbon number of the alka (poly) enylene group is preferably 2-4. Specific examples thereof include _{-CH = CH -, - CH =} CH-CH 2 -, - CH 2 -CH = CH-CH 2 -, - CH = CH-CH = CH- , and the like.
When X is a saturated aliphatic group or an unsaturated aliphatic group and the group is asymmetrical, the binding direction may be any.
The X, each of the two X are independently an oxygen atom, a sulfur atom, an ester bond, a thioester _{bond, -NH -, - CH 2 -CH} 2 - or is preferably -CH = CH-, an ester bond , thioester bond, -NH -, _- it is more preferable or _{-CH = CH- - CH 2 -CH 2} . Y is preferably an oxygen atom.

R in the above formula (1) is a site that imparts flexibility to the main chain of the specific polymer. Therefore, as the R, the following formula - _{(CH 2) n} - or _{- (CR'H-CH 2) -} (O-CR'H-CH 2) m -
(Wherein R ′ is independently a hydrogen atom, a methyl group or an ethyl group;
n is an integer from 1 to 12;
m is an integer of 1-3. )
It is preferable that it is group represented by these. However, as understood from the definition of R in the formula (1), the upper limit value of the carbon number in the above formula is limited to 12.
R ′ in the above formula is preferably a hydrogen atom;
n is preferably from 2 to 8, more preferably from 4 to 6;
m is preferably 1 or 2.
The four phenylene groups present in the formula (1) are each independently preferably a 1,3-phenylene group or a 1,4-phenylene group, and more preferably a 1,4-phenylene group.
Examples of the structure represented by the above formula (1) include structures represented by the following formulas (1-1) to (1-12).

(In the above formulas (1-1) to (1-12), n is an integer of 2 to 12, and m is 1 or 2.)
In the above formulas (1-1), (1-3), (1-5), (1-7), (1-9) and (1-11), n is preferably 2-8. More preferably, it is 4-6.
As long as the specific polymer in the present invention is at least one polymer selected from the group consisting of a polyamic acid having a structure represented by the above formula (1) in the main chain and an imidized polymer thereof, the remainder The structure of is arbitrary and may be obtained by any synthesis method.
The specific polymer in the present invention includes, for example, a tetracarboxylic dianhydride including a tetracarboxylic dianhydride having a structure represented by the above formula (1),
It can be one or more polymers selected from the group consisting of polyamic acids obtained by reacting diamines and imidized polymers thereof, or tetracarboxylic dianhydrides,
It may be at least one polymer selected from the group consisting of a polyamic acid obtained by reacting a diamine containing a diamine having a structure represented by the above formula (1) and an imidized polymer thereof. Of these, the latter is preferred from the viewpoint of ease of raw material monomer synthesis.

[Tetracarboxylic dianhydride]
Examples of the tetracarboxylic dianhydride used for synthesizing the specific polymer in the present invention include an aliphatic tetracarboxylic dianhydride, an alicyclic tetracarboxylic dianhydride, and an aromatic tetracarboxylic dianhydride. And so on. 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, a compound represented by the following formula (T1), etc. can be mentioned, respectively.
The tetracarboxylic dianhydride described in Patent Document 4 (Japanese Patent Laid-Open No. 2010-97188) can be used.

(In Formula (T1), when there are a plurality of Zs, each independently represents an oxygen atom, a sulfur atom, an ester bond, a thioester bond or —NH—;
When there are a plurality of R ^{1 s} , each independently represents an arylene group having 6 to 18 carbon atoms or an alkylene group having 2 to 6 carbon atoms; and n1 is an integer of 0 to 2. )
Z in the formula (T1) is preferably an oxygen atom or an ester bond. Examples of the arylene group for R ¹ include a phenylene group, a naphthylene group, and a biphenylylene group;
Examples of the alkylene group include a 1,2-ethylene group, a 1,2-propylene group, and a 1,3-propylene group. R ¹ is preferably an arylene group, and when there are a plurality of R ^{1 s} , it is particularly preferably a 1,4-phenylene group, a 2,6-naphthylene group, or a 4,4′-biphenylylene group. preferable. n1 is preferably 0 or 1.
Specific examples of the compound represented by the formula (T1) include, for example, compounds represented by the following formulas (T-1) and (T-2).

  The tetracarboxylic dianhydride used for synthesizing the specific polymer in the present invention preferably contains a compound represented by the above formula (T1), and a compound represented by the above formula (T1) It is preferable to contain 20 mol% or more with respect to all tetracarboxylic dianhydrides, more preferably 50 mol% or more, and still more preferably 80 mol% or more.

[Diamine]
The diamine used for synthesizing the specific polymer in the present invention preferably includes a diamine having a structure represented by the above formula (1). Examples of the diamine having the structure represented by the formula (1) include a compound represented by the following formula (A1) (hereinafter referred to as “specific diamine”).

(In the formula (A1), X, Y and R each have the same meaning as in the above formula (1).)
The bonding directions of the four phenylene groups present in the formula (A1) are the same as those described above for the phenylene groups in the formula (1).
As a preferable example of the specific diamine in the present invention, for example, in the structure represented by each of the above formulas (1-1) to (1-12), two amino groups are represented by two bonds represented by “*”. And the like obtained by directly bonding each of them.
As the diamine used for synthesizing the specific polymer in the present invention, only the specific diamine may be used, or other diamine may be used in combination with the specific diamine.

Other diamines that can be used here can be classified into, for example, diamines having a pretilt angle developing group and diamines having no pretilt angle developing group.
The diamine having a pretilt angle developing group is preferably an aromatic diamine having a pretilt angle developing group. Specific examples thereof include dodecanoxy-2,4-diaminobenzene, tetradecanoxy-2,4-diaminobenzene, and the like. 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, cholesteryloxy-3,5-diaminobenzene, cholesta Ruoxy-2,4-diaminobenzene, cholesteryloxy-2,4-diaminobenzene, cholestanyl 3,5-diaminobenzoate, cholesteryl 3,5-diaminobenzoate, lanostannyl 3,5-diaminobenzoate, 3,6- Bis (4-aminobenzoyloxy) cholestane, 3,6-bis (4-aminophenoxy) cholestane, 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-aminophenyl) -4- (4-heptyl cyclohexyl) benzamide, it can be mentioned compounds represented by the following formula (A-1).

(In the formula (A-1), X ^I and X ^II are each a single bond, ^* —O—, ^* —COO— or ^* —OOC— (where the bond with “*” represents the formula (A -I) facing left));
R ^I is a single bond, a methylene group or an alkylene group having 2 or 3 carbon atoms;
a is 0 or 1, b is an integer of 0 to 2, provided that a and b are not 0 at the same time;
c is an integer of 1-20. )
The formula ^{(A-1) X I -R} I -X II in - a divalent methylene group as a group, an alkylene group having 2 or 3 carbon atoms ^represented, * ^-O-, * -COO- or ^* It is preferably —O—CH ₂ CH ₂ —O— (wherein a bond marked with “*” is bonded to a diaminophenyl group). When c is 3 or more in the group —C _c H _{2c + 1} , this group is preferably linear. The two amino groups in the diaminophenyl group are preferably in the 2,4-position or 3,5-position with respect to the other groups. Specific examples of the compound represented by the formula (A-1) include, for example, the following formulas (A-1-1-1), (A-1-1-2), and (A-1-2).

(In the above formula, “n-” represents that each is linear.)
It is preferable that it is a compound represented by each of these.
Examples of the diamine having no pretilt angle-expressing group include aliphatic diamines, alicyclic diamines, aromatic diamines, and diaminoorganosiloxanes that do not have a pretilt angle-expressing group.
Among the diamines having no pretilt angle-expressing group, examples of the aliphatic diamine include 1,1-metaxylylenediamine, 1,3-propanediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, and the like;
Examples of the alicyclic diamine include 1,4-diaminocyclohexane, 4,4′-methylenebis (cyclohexylamine), 1,3-bis (aminomethyl) cyclohexane, and the like;

Examples of aromatic diamines having no pretilt angle-expressing group include aromatic diamines such as o-phenylenediamine, m-phenylenediamine, 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) Xafluoropropane, 4,4 ′-(p-phenylenediisopropylidene) bisaniline, 4,4 ′-(m-phenylenediisopropylidene) bisaniline, 1,4-bis (4-aminophenoxy) benzene, 4,4 '-Bis (4-aminophenoxy) biphenyl, 2,6-diaminopyridine, 3,4-diaminopyridine, 2,4-diaminopyrimidine, 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) -pipe Gin, 3,5-diaminobenzoic acid, 4- (4'-trifluoromethoxybenzoyloxy) cyclohexyl-3,5-diaminobenzoate, 4- (4'-trifluoromethylbenzoyloxy) cyclohexyl-3,5 -Diaminobenzoate, 2,4-diamino-N, N-diallylaniline, 4-aminobenzylamine, 3-aminobenzylamine, 1- (2,4-diaminophenyl) piperazine-4-carboxylic acid, 4- (morpholine) -4-yl) benzene-1,3-diamine, 1,3-bis (N- (4-aminophenyl) piperidinyl) propane, α-amino-ω-aminophenylalkylene, 4- (2-aminoethyl) aniline A compound represented by the following formula (N);

Examples of the diaminoorganosiloxane having no pretilt angle-expressing group include 1,3-bis (3-aminopropyl) -tetramethyldisiloxane, respectively.
The tetracarboxylic dianhydride described in Patent Document 4 (Japanese Patent Laid-Open No. 2010-97188) can be used.

The diamine used for synthesizing the specific polymer in the present invention preferably contains 5 mol% or more of the above specific diamine, more preferably 10 mol% or more, based on the total diamine, 30 More preferably, it is contained in an amount of ˜80 mol%.
The liquid crystal aligning agent of the present invention is particularly suitable for forming a liquid crystal alignment film applied to a so-called horizontal alignment type liquid crystal display element such as a TN type, STN type, IPS type, or FFS type by a photo-alignment method. . Therefore, it is preferable to limit the use ratio of the diamine having a pretilt angle developing group among the diamines to be used to a certain value or less. The proportion of the diamine having a pretilt angle-expressing group is preferably 20 mol% or less, more preferably 10 mol% or less, particularly 5 mol%, based on the total diamine used. The following is preferable.

<Synthesis of specific polymer>
The polyamic acid as the specific polymer in the present invention can be obtained by reacting the above tetracarboxylic dianhydride and diamine together with a terminal blocking agent used as necessary.
The imidized polymer as the specific polymer in the present invention can be obtained by dehydrating and ring-closing the polyamic acid obtained as described above to imidize.
Examples of the end capping agent include carboxylic acid monoanhydrides such as maleic anhydride, phthalic anhydride, and itaconic anhydride;
Monoamines such as aniline, cyclohexylamine, n-butylamine;
Examples thereof include monoisocyanate compounds such as phenyl isocyanate and naphthyl isocyanate.
The proportion of tetracarboxylic dianhydride and diamine used in the polyamic acid synthesis reaction is such that the number of equivalents of the tetracarboxylic dianhydride acid anhydride group is 0 with respect to 1 equivalent of the amino group of the diamine. A ratio of 2 to 2 equivalents is preferable, and a ratio of 0.3 to 1.2 equivalents is more preferable. When using terminal blocker, it is preferable that the use ratio shall be 20 weight or less with respect to a total of 100 weight part of tetracarboxylic dianhydride and diamine.
The polyamic acid synthesis reaction is preferably carried out in an organic solvent, preferably at a temperature of -20 to 150 ° C, more preferably at a temperature of 0 to 100 ° C, preferably 0.1 to 24 hours, more preferably 0.5. ~ 12 hours.

Examples of the organic solvent that can be used in the synthesis of the polyamic acid include an aprotic polar solvent, phenol and derivatives thereof, alcohol, ketone, ester, ether, halogenated hydrocarbon, hydrocarbon and the like. Among these organic solvents, at least one selected from the group consisting of an aprotic polar solvent and phenol and derivatives thereof (first group organic solvent) is used, or selected from the first group of organic solvents It is preferable to use 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 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.
Particularly preferably, N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, dimethyl sulfoxide, γ-butyrolactone, tetramethylurea, hexamethylphosphortriamide, m-cresol, xylenol, 3 It is preferable to use at least one selected from the group consisting of -methoxy-N, N-dimethylpropionamide, 3-butoxy-N, N-dimethylpropionamide and halogenated phenol.
The amount of organic solvent used (a) is the proportion of the total amount (b) of tetracarboxylic dianhydride and diamine (and end capping agent, if present) in the total amount (a + b) of the polymerization reaction solution ( b / (a + b)) is preferably in an amount of 0.1 to 50% by weight.
As described above, a solution containing polyamic acid is obtained. This solution can be used for the next imidation reaction or the preparation of the liquid crystal aligning agent of the present invention as it is or after isolating and purifying the polyamic acid by a known method as required.

When an imidized polymer of polyamic acid is used as the specific polymer in the present invention, the imidization rate of the imidized polymer may be 30% or more from the viewpoint of ensuring the expression of good electrical characteristics. Preferably, it is 50% or more, more preferably 65% or more. On the other hand, from the viewpoint of ensuring the solubility of the specific polymer that is an imidized polymer and improving the applicability of the obtained liquid crystal aligning agent, the imidation rate is preferably 99% or less, and 80% or less. It is more preferable.
In order to dehydrate and cyclize and imidize the polyamic acid obtained as described above, preferably (i) a method of heating the polyamic acid, or (ii) dissolving the polyamic acid in an organic solvent, Is carried out by adding a dehydrating agent and a dehydrating ring-closing catalyst and heating as necessary.
The reaction temperature in the method (i) of heating the polyamic acid is preferably 50 to 200 ° C, more preferably 60 to 170 ° C. When the reaction temperature is less than 50 ° C., the dehydration ring-closing reaction does not proceed sufficiently, and when the reaction temperature exceeds 200 ° C., the molecular weight of the imidized polymer obtained may decrease. The reaction time is preferably 1.0 to 24 hours, more preferably 1.0 to 12 hours.

  On the other hand, in the method (ii) of adding a dehydrating agent and a dehydrating ring-closing catalyst to the polyamic acid solution, an acid anhydride such as acetic anhydride, propionic anhydride, or trifluoroacetic anhydride is used as the dehydrating agent. Can do. Although the usage-amount of a dehydrating agent is based on the imidation ratio desired, it is preferable to set it as 0.01-20 mol with respect to 1 mol of the amic acid structure of a polyamic acid. Moreover, as a dehydration ring closure catalyst, tertiary amines, such as a pyridine, a collidine, a lutidine, a triethylamine, can be used, for example. 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. The imidation rate can be increased as the amount of the above dehydrating agent and dehydrating ring-closing agent increases. 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 solution containing an imidized polymer of polyamic acid is obtained. This solution can be used for the preparation of the liquid crystal aligning agent of the present invention as it is or after isolating and purifying the imidized polymer by a known method if necessary.

<Other ingredients>
The liquid crystal aligning agent of the present invention contains the specific polymer as described above as an essential component, and is preferably configured as a solution composition in which these are dissolved in a solvent described later, but other components as necessary. May further be contained.
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 specific polymer, and can be used for improving the solution properties (coating properties) and electrical properties of the liquid crystal aligning agent of the present invention.
Other polymers include polyamic acid not having the structure represented by the above formula (1) in the main chain, imidized polymer of the polyamic acid, polyamic acid ester, polyester, polyamide, polysiloxane, cellulose derivative, Examples include polyacetal, polystyrene derivatives, poly (styrene-phenylmaleimide) derivatives, poly (meth) acrylates, and the like.
The use ratio of the other polymer is preferably 50% by weight or less, and more preferably 30% by weight or less with respect to 100 parts by weight of the specific polymer.

[Epoxy compound]
Examples of the epoxy 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, and 1,6-hexane. Diol 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'-diaminodiphenylme Emissions, 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 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 specific polymer.

[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-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-aminopropyltri Examples include methoxysilane, N-benzyl-3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, and N-phenyl-3-aminopropyltriethoxysilane.
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 specific polymer.

<Liquid crystal aligning agent>
The liquid crystal aligning agent of the present invention is constituted by dissolving the specific polymer as described above and other components optionally blended as required, preferably in a solvent.
As a solvent that can be used in the liquid crystal aligning agent of the present invention, an organic solvent is preferably used. For example, 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 A carbonate etc. can be mentioned. These can be used alone or in admixture of two or more.

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 thus 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 10-45 degreeC, More preferably, it is 20-30 degreeC.

<Method for forming liquid crystal alignment film>
A liquid crystal alignment film can be formed using the liquid crystal aligning agent of the present invention. That is, a liquid crystal alignment film can be formed by applying a liquid crystal aligning agent of the present invention on a substrate to form a coating film, and passing through the process of irradiating the coating film with light.
The liquid crystal aligning agent of this invention is applicable to manufacture of the liquid crystal display element which has appropriate liquid crystal cells, such as TN type, STN type, IPS type, FFS type, VA type, MVA type. However, application to a liquid crystal display element having a so-called horizontal alignment type liquid crystal cell such as a TN type, STN type, IPS type, or FFS type is preferable in that the advantageous effects of the present invention can be maximized. .
When the liquid crystal alignment film formed from the liquid crystal alignment film of the present invention is applied to a TN type or STN type liquid crystal display element, a pair of two substrates provided with a patterned transparent conductive film is used as the substrate. The liquid crystal aligning agent used is applied on the surface of each substrate on which the transparent conductive film is formed. On the other hand, when the liquid crystal alignment film is applied to an IPS-type or FFS-type liquid crystal display element, the substrate includes a substrate having an electrode in which a transparent conductive film or a metal film is patterned in a comb shape on one side, and an electrode. The liquid crystal aligning agent is applied to the surface on which the comb-like electrodes are formed and one surface of the counter substrate.

In any of the above cases, examples of the substrate include glass such as float glass and soda glass; and a transparent substrate made of plastic such as polyethylene terephthalate, polybutylene terephthalate, polyethersulfone, and polycarbonate. As the transparent conductive film, for example, an ITO film made of In ₂ O ₃ —SnO _{2 or} a NESA (registered trademark) film made of SnO ₂ can be used. As the metal film, for example, a film made of a metal such as chromium can be used. For patterning the transparent conductive film and the metal film, for example, a method of forming a pattern by a photo-etching method or a sputtering method after forming a transparent conductive film without a pattern, or a mask having a desired pattern when forming the transparent conductive film The method using can be used.
In order to further improve the adhesion between the substrate and the transparent conductive film or metal film and the coating film when the liquid crystal aligning agent for photo-alignment is applied on the substrate, A functional silane compound, titanate compound or the like may be applied.
The application of the liquid crystal aligning agent for photo-alignment on the substrate can be preferably performed by an appropriate application method such as an offset printing method, a spin coating method, a roll coater method, an ink jet printing method, etc. A coating film is formed by prebaking. Prebaking conditions are 0.1 to 5 minutes, for example in 40-120 degreeC.

Next, the coating film formed as described above is irradiated with light to impart liquid crystal alignment capability to the liquid crystal alignment film. Here, as the light, for example, ultraviolet light and visible light including light having a wavelength of 150 to 800 nm can be used, but it is preferable to use ultraviolet light including light having a wavelength of 200 to 400 nm. Irradiation light may be polarized or non-polarized, but is preferably polarized. As the light source, for example, a low-pressure mercury lamp, a high-pressure mercury lamp, a deuterium lamp, a metal halide lamp, an argon resonance lamp, a xenon lamp, a Hg-Xe lamp, an excimer laser, or the like can be used. The light in the preferred wavelength region can be obtained by means of using the light source in combination with, for example, a filter or a diffraction grating.
The dose of light is preferably 400~50,000J / ^{m 2,} more preferably from 1,000~10,000J / ^{m 2.}
The coating film that has been irradiated with light and given the ability to align liquid crystal as described above is preferably further heated (post-baked) before use. This post-bake condition is preferably 120 to 300 ° C., more preferably 150 to 250 ° C., preferably 5 to 200 minutes, more preferably 10 to 100 minutes.
The film thickness of the liquid crystal aligning film formed from the liquid crystal aligning agent of this invention becomes like this. Preferably it is 0.001-1 micrometer, More preferably, it is 0.005-0.5 micrometer.

<Liquid crystal display element>
Using the substrate on which the liquid crystal alignment film is formed as described above by the method of the present invention, for example, a liquid crystal display element can be produced as follows.
A pair of substrates on which the liquid crystal alignment film is formed as described above is prepared, and a liquid crystal cell having a configuration in which the liquid crystal is sandwiched between the pair of substrates is manufactured.
As the liquid crystal, for example, nematic liquid crystal, smectic liquid crystal, or the like can be used. Those having positive dielectric anisotropy forming a nematic liquid crystal are preferred, such as biphenyl liquid crystal, phenyl cyclohexane liquid crystal, ester liquid crystal, terphenyl liquid crystal, biphenyl cyclohexane liquid crystal, pyrimidine liquid crystal, dioxane liquid crystal, Bicyclooctane liquid crystals, cubane liquid crystals, and the like are used. In addition, for example, cholesteric liquid crystals such as cholestyl chloride, cholesteryl nonate, cholesteryl carbonate;
Chiral agents such as those sold under the trade names “C-15” and “CB-15” (Merck)
A ferroelectric liquid crystal such as p-decyloxybenzylidene-p-amino-2-methylbutylcinnamate may be further added and used.

In order to manufacture a liquid crystal cell, for example, 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 a method of sealing the injection hole after injecting and filling liquid crystal into the cell gap defined by the substrate surface and the sealing agent;
For example, a photo-curable sealant is applied to a predetermined number of places on one of the two substrates on which the liquid crystal alignment film is formed, and the liquid crystal is dropped on a predetermined number of places on the liquid crystal alignment film surface. A method in which the other substrate is bonded so that the liquid crystal alignment films face each other, and then the entire surface of the substrate is irradiated with ultraviolet light to cure the sealant (ODF method = One Drop Fill method)
And so on. As the sealing agent, for example, an epoxy resin containing aluminum oxide spheres as a spacer and a curing agent can be used.
In any of the above methods, it is desirable to remove the flow alignment at the time of filling the liquid crystal by heating the liquid crystal cell to a temperature at which the liquid crystal used takes an isotropic phase and then gradually cooling it to room temperature.

And a liquid crystal display element can be manufactured by bonding a polarizing plate on the outer surface of a liquid crystal cell. Here, a desired liquid crystal display element can be obtained by appropriately adjusting the angle of the polarizing plate in the two substrates on which the liquid crystal alignment film is formed. Examples of the polarizing plate include a polarizing plate formed by sandwiching a polarizing film called “H film” in which iodine is absorbed while stretching and orientation of polyvinyl alcohol are sandwiched between cellulose acetate protective films, or a polarizing plate made of the H film itself. .
The liquid crystal display device manufactured as described above is excellent in various performances such as display characteristics and electrical characteristics.

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 in the following polymer synthesis examples is a value measured at 25 ° C. using an E-type rotational viscometer for the polymer solution indicated in each synthesis example.

<Synthesis example of specific diamine>
In the following synthesis examples, the necessary amount in the subsequent synthesis of the polymer was secured by repeating at the following scale as necessary.
Synthesis Example A-1
Compound (A-1-1) was synthesized according to Scheme 1 below.

(1) Synthesis of Compound (A-1-1a) In a reaction vessel, methyl 4-hydroxybenzoate 105.0 mmol (15.98 g), 1,4-dibromobutane 50.0 mmol (10.80 g), potassium carbonate 120.0 mmol (16.59 g) and N, N-dimethylacetamide 100 mL were charged and mixed, and the reaction was performed at 80 ° C. with stirring for 6 hours. From the middle of the reaction, formation of crystals was observed in the reaction system.
After completion of the reaction, 500 mL of ethyl acetate and 300 mL of distilled water were added to the reaction mixture in this order, followed by separation and washing. After washing, the collected organic layer is placed under reduced pressure, and the total amount of the solid obtained by removing the solvent is collected, washed with ethanol, and then dried under reduced pressure to give a white crystalline compound (A- 1-1a) 44.4 mmol (15.91 g) was obtained (yield 88.8%).
(2) Synthesis of compound (A-1-1b) In the reaction vessel, the total amount of compound (A-1-1a) obtained above (44.4 mmol (15.91 g)), lithium hydroxide monohydrate 133.2 mmol (5.59 g), 60 mL of methanol, 40 mL of ethanol and 30 mL of distilled water were charged and mixed, and the reaction was performed at 80 ° C. with stirring for 3 hours. After completion of the reaction, 1N hydrochloric acid mL was added to the reaction mixture to make the liquid acidic, and the resulting powder was collected by filtration. The powder was thoroughly washed sequentially with distilled water and ethanol and then dried under reduced pressure to obtain 41.6 mmol (13.73 g) of compound (A-1-1b) (yield) 93.6%).

(3) Synthesis of compound (A-1-1c) In a reaction vessel, the total amount of compound (A-1-1b) obtained above (41.6 mmol (13.73 g)), thionyl chloride 35 mL and N, N -Dimethylformamide was charged and mixed, and reacted at 80 ° C for 1 hour with stirring. After completion of the reaction, the reaction mixture was placed under reduced pressure in a water aspirator to remove unreacted thionyl chloride. Tetrahydrofuran 100mL was added to the obtained solution, and this was made into solution <1>.
In a separate reaction vessel, 87.3 mmol (12.14 g) of 4-nitrophenol, 124.7 mmol (17.3 mL) of triethylamine, and 150 mL of tetrahydrofuran were charged and stirred in an ice bath. The solution <1> was added dropwise thereto over 1 hour, and the reaction was performed at 25 ° C. with stirring for 4 hours. After completion of the reaction, 500 mL of ethyl acetate was added to the reaction mixture, and then washed sequentially with 1N hydrochloric acid and distilled water. At this time, the powder was floating on the organic layer side.
The above powder was collected by filtration and dried under reduced pressure to obtain 36.9 mol (21.15 g) of light yellow powdered compound (A-1-1c) (yield 88.8%). .

(4) Synthesis of Compound (A-1-1) In a reaction vessel under a nitrogen atmosphere, 36.9 mol (21.15 g) of the compound (A-1-1c) obtained above and 738 mmol (48.3 g) of zinc A mixture of 147.6 mmol (7.75 g) of ammonium chloride, 332 mL of tetrahydrofuran and 37 mL of ethanol was mixed and stirred in an ice bath. Distilled water (18.5 mL) was added dropwise thereto, and the reaction was carried out by sequentially stirring at 25 ° C. for 8 hours and at 70 ° C. for 1 hour. After completion of the reaction, insoluble matters such as inorganic salts produced were removed by filtration from the reaction mixture. The organic layer obtained by adding 1,850 mL of ethyl acetate to the filtrate was washed 4 times with 738 mL of distilled water. After filtering the organic layer after washing, the solvent was removed under reduced pressure to obtain a powder. The powder was washed successively with ethanol and ethyl acetate, and the solvent was completely removed under reduced pressure to obtain 21.0 mmol (10.7 g) of compound (A-1-1) (yield 56). .8%).

Synthesis Example A-2
Compound (A-8-1) was synthesized according to Scheme 2 below.

(Ts in the above formula (A-8-1b) is a tosyl group.)
(1) Synthesis of Compound (A-8-1a) A 200 mL three-necked flask equipped with a nitrogen introduction tube, a reflux tube and a thermometer was charged with 20 g of 4-nitrophenylacetic acid, 10 g of p-hydroxybenzaldehyde and 5 mL of piperidine, and 140 The reaction was carried out at 1 ° C. for 1 hour. Subsequently, 75 mL of ethanol, 25 mL of water and 0.5 mL of acetic acid were added thereto, and the reaction was performed under reflux for 2 hours. After completion of the reaction, the produced precipitate was collected by filtration and recrystallized using isopropanol to obtain 17 g of a reddish brown compound (A-8-1a).
(2) Synthesis of Compound (A-8-1c) A 1 L three-necked flask equipped with a reflux tube and a nitrogen inlet tube was charged with 14 g of Compound A2-8-1a) obtained above, 20 g of potassium carbonate and 460 mL of acetonitrile, The reaction was carried out under reflux for 30 minutes. Subsequently, 12 g of compound (A-8-1b) was added thereto, and the reaction was performed under reflux for 24 hours. After completion of the reaction, the reaction mixture was suspended in 1 L of ethyl acetate, suspended once by 500 mL of dilute hydrochloric acid and 3 times by 500 mL of water, and then the solvent was removed from the organic layer under reduced pressure. The obtained yellow crystals were collected by filtration, and the solvent was completely removed under reduced pressure to obtain 14 g of Compound (A-8-1c).
(3) Synthesis of Compound (A-8-1) In a 1 L three-necked flask equipped with a reflux tube, a nitrogen introduction tube and a thermometer, 13 g of the compound (A-8-1c) obtained above, 5% by weight palladium carbon 1.3 g of powder, 250 mL of tetrahydrofuran, 35 mL of ethanol and 12 mL of 80 wt% hydrazine monohydrate were charged, and the reaction was performed under reflux for 6 hours. After completion of the reaction, 500 mL of ethyl acetate was added to the filtrate obtained by filtering the reaction mixture, followed by washing with 500 mL of water three times. The washed organic layer was concentrated and the precipitated white crystals were collected by filtration, and the solvent was completely removed under reduced pressure to obtain 9.5 g of white crystals of the compound (A-8-1).

<Synthesis of polymer>
Abbreviations of tetracarboxylic dianhydride used in the following polymer synthesis examples have the following meanings, respectively.
Compound (T-1): Compound represented by the above formula (T-1) Compound (T-2): Compound represented by the above formula (T-2)

Synthesis Example P-1
9.3 g of compound (T-1) as tetracarboxylic dianhydride and 10.7 g of compound (A-1-1) obtained in Synthesis Example A-1 as diamine are dissolved in 80 g of N-methyl-2-pyrrolidone. And the solution containing 20 weight% of polyamic acids (PA-1) was obtained by reacting at room temperature for 4 hours. The solution viscosity of this solution was 2,700 mPa · s.
Synthesis Example P-2
7.4 g of compound (T-2) as tetracarboxylic dianhydride and 13.6 g of compound (A-1-1) obtained in Synthesis Example A-1 as diamine are dissolved in 80 g of N-methyl-2-pyrrolidone. And the solution containing 20 weight% of polyamic acids (PA-2) was obtained by reacting at room temperature for 4 hours. The solution viscosity of this solution was 1,900 mPa · s.

Synthesis Example P-3
9.5 g of compound (T-1) as tetracarboxylic dianhydride and 10.5 g of compound (A-8-1) obtained in Synthesis Example A-1 as diamine are dissolved in 80 g of N-methyl-2-pyrrolidone. Then, a reaction containing 20% by weight of polyamic acid (PA-3) was obtained by reacting at room temperature for 4 hours. The solution viscosity of this solution was 3,000 mPa · s.
Comparative Synthesis Example R-1
13.3 g of compound (T-1) as tetracarboxylic dianhydride and 6.7 g of 4-aminophenyl-4-aminobenzoate as diamine are dissolved in 80 g of N-methyl-2-pyrrolidone and reacted at room temperature for 4 hours. To obtain a solution containing 20% by weight of polyamic acid (R-1). The solution viscosity of this solution was 1,500 mPa · s.
Comparative Synthesis Example R-2
13.6 g of compound (T-1) as tetracarboxylic dianhydride and 6.4 g of 1,2-bis (4-aminophenyl) ethane as diamine are dissolved in 80 g of N-methyl-2-pyrrolidone, and 4 at room temperature. By performing the reaction for a time, a solution containing 20% by weight of polyamic acid (R-2) was obtained. The solution viscosity of this solution was 2,900 mPa · s.

<Preparation and evaluation of liquid crystal aligning agent>
Example 1
1. Preparation of liquid crystal aligning agent To the solution containing polyamic acid (PA-1) obtained in Synthesis Example (P-1) above, N-methyl-2-pyrrolidone (NMP) and butyl cellosolve (BC) were added and stirred sufficiently. The solution was NMP: BC = 60: 40 (weight ratio) and the solid content concentration was 2.5% by mass. A liquid crystal aligning agent was prepared by filtering this solution using a filter having a pore diameter of 1 μm.

2. Evaluation of Liquid Crystal Alignment Agent (1) Manufacture of Liquid Crystal Cell for Liquid Crystal Alignment, Voltage Holding Ratio and Contrast Evaluation Each of two transparent glass substrate with transparent electrode (a pair) made of the above prepared liquid crystal alignment agent On the electrode surface, coating was performed using a spinner so that the film thickness was 0.1 μm, followed by heating (prebaking) at 80 ° C. for 1 minute to form respective coating films. These coating surfaces were irradiated with polarized ultraviolet rays containing a 254 nm emission line from the direction normal to the substrate using an Hg-Xe lamp in the normal direction of the substrate, and then heated in a clean oven at 230 ° C. for 1 hour. (Post-bake) was performed to form liquid crystal alignment films on two (a pair of) substrates.
Next, with respect to one of the pair of substrates subjected to the above light irradiation treatment, an epoxy resin adhesive containing aluminum oxide spheres having a diameter of 5.5 μm is left at the outer peripheral edge of the surface on which the liquid crystal alignment film is formed. After the agent is screen-printed and applied, the pair of substrates are overlapped and pressure-bonded so that the liquid crystal alignment film formation surfaces face each other and the projection directions of the polarization planes upon light irradiation coincide with each other. The adhesive was heat cured by heating for a period of time.
Next, a nematic liquid crystal (MLC-7028, manufactured by Merck & Co., Inc.) was filled between the pair of substrates from the liquid crystal injection port, and then the liquid crystal injection port was sealed with an epoxy adhesive. Furthermore, in order to remove the flow alignment at the time of liquid crystal injection, this was heated to 150 ° C. and then gradually cooled to room temperature to produce a liquid crystal cell.

(2) Evaluation of liquid crystal orientation About the liquid crystal cell manufactured above, the presence or absence of an abnormal domain when an AC voltage of 5 V was turned on / off (applied / released) was observed with a polarizing microscope.
When the abnormal domain was not observed, the liquid crystal alignment was “good”, and when one of the abnormal domains was observed in the display region, the liquid crystal alignment was evaluated as “bad”. It was determined as “good”.
(3) Evaluation of voltage holding ratio After the voltage of 5 V was applied to the liquid crystal cell manufactured as described above for 60 microseconds and with a span of 167 milliseconds, the voltage holding ratio after 167 milliseconds from the application release was measured. However, the voltage holding ratio of the liquid crystal cell was 98%.
A model name “VHR-1” manufactured by Toyo Technica Co., Ltd. was used as a voltage holding ratio measuring apparatus.

(4) Evaluation of contrast The contrast after the liquid crystal cell produced above was driven for 30 hours was examined.
Using a device in which a polarizer and an analyzer are installed between a light source and a light amount detector, the liquid crystal cell manufactured above is placed between the polarizer and the analyzer, and light transmission under crossed Nicols The amount β was examined, and these values were substituted into the following formula (1) to calculate the minimum relative transmittance (%).
Minimum relative transmittance (%) = (β−B0) / (B100−B0) × 100 (1)
(In the formula (1), B0 is the light transmission amount of the blank under crossed Nicols;
B100 is the light transmission of the blank under para-Nicol; and β is the light transmission measured with the liquid crystal cell placed between the polarizer and the analyzer under crossed Nicol. )
The minimum relative transmittance calculated by the formula (1) indicates the level of the black level in the dark state, and it can be evaluated that the smaller the value of the minimum relative transmittance, the better the contrast.
When the minimum relative transmittance is less than 0.5%, the contrast is “good”, when 0.5 to 1.0%, the contrast is “good”, and when it exceeds 1.0%, the contrast is “ Rated as “bad”. The minimum relative transmittance of the liquid crystal cell was 0.3%, and therefore the contrast was judged to be “good”.

(5) Manufacture of liquid crystal cell for evaluation of afterimage characteristics As the pair of substrates, except that a substrate pair having the following configuration was used, “(2) Manufacture of liquid crystal cell for liquid crystal orientation, voltage holding ratio and contrast evaluation” In the same manner as described above, a liquid crystal cell for evaluation of afterimage characteristics (FFS type liquid crystal cell) was manufactured, and a polarizing plate was bonded to both outer surfaces of the substrate to obtain a liquid crystal display element.
Here, as an electrode substrate, a glass substrate on which two systems of electrodes (electrode A (101) and electrode B (102)) made of chromium having a comb-like pattern shown in FIG. 1 are formed;
As a counter substrate, a glass substrate on which no electrode is formed,
Each was used. The liquid crystal aligning agent was applied to the electrode forming surface of the electrode substrate and one surface of the counter substrate.
(6) Evaluation of afterimage characteristics (burn-in) The liquid crystal display device manufactured as described above was placed in an environment of 25 ° C. and 1 atm. No voltage was applied to electrode B, and AC voltage 3.5 V and DC voltage were applied to electrode A. A composite voltage of 5V was applied for 2 hours. Immediately after 2 hours, an AC voltage of 4 V was applied to both electrode A and electrode B. Then, the time from when the voltage of 4V AC was started to be applied to both electrodes until the difference in light transmittance between the two electrodes could not be visually confirmed was measured. If this time is less than 100 seconds, the afterimage characteristics “good”;
When it was 100 seconds or more and less than 150 seconds, the afterimage characteristics were “possible”; and when it was 150 seconds or more, the afterimage characteristics were evaluated as “bad”. The afterimage characteristics of the liquid crystal display element were “good”. It was.

Examples 2-4 and Comparative Examples 1 and 2
Instead of the solution containing polyamic acid (PA-1), solutions containing polyamic acid of the type shown in Table 1 were used, respectively, and "2. (1) Liquid crystal orientation, voltage holding ratio and contrast evaluation" In the same manner as in Example 1 except that the polarized UV irradiation dose in “Manufacturing liquid crystal cell for liquid crystal” and “2. (5) Manufacture of liquid crystal cell for evaluation of afterimage characteristics” is as shown in Table 1, respectively. A liquid crystal aligning agent was prepared, and various evaluations were performed using the liquid crystal aligning agent.
The evaluation results are shown in Table 1.

  As readily understood from Table 1 above, the liquid crystal aligning agent of the present invention containing a polymer having the structure represented by the above formula (1) in the main chain is applied when the photo-alignment method is applied thereto. In addition to being excellent in liquid crystal alignment and voltage holding ratio, it was verified that a liquid crystal alignment film excellent in both contrast and afterimage characteristics was obtained.

Claims (8)

A liquid crystal aligning agent comprising at least one polymer selected from the group consisting of a polyamic acid having a structure represented by the following formula (1) in the main chain and an imidized polymer thereof.

(In formula (1), two X's are each independently an oxygen atom, a sulfur atom, an ester bond, a thioester bond, an amide bond, -NH-, -C (= O)-, or a carbon number of 1-10. A divalent saturated aliphatic group or a divalent unsaturated aliphatic group having 2 to 10 carbon atoms;
Two Y's are each independently a single bond, oxygen atom, sulfur atom, ester bond or thioester bond;
R is a methylene group or an alkylene group having 2 to 12 carbon atoms which may be interrupted by an oxygen atom; and “*” represents a bond. ) R in the above formula (1) is a compound represented by the following formula - _{(CH 2) n} - or _{- (CR'H-CH 2) -} (O-CR'H-CH 2) m -
(Where R ′ is a hydrogen atom, a methyl group or an ethyl group;
n is an integer from 1 to 12;
m is an integer of 1-3. )
The liquid crystal aligning agent of Claim 1 which is group represented by these. The polymer is at least one selected from the group consisting of a polyamic acid obtained by reacting a tetracarboxylic dianhydride and a diamine containing a compound represented by the following formula (A1) and an imidized polymer thereof. The liquid crystal aligning agent of Claim 1 which is a polymer of these.

(In the formula (A1), X, Y and R each have the same meaning as in the above formula (1).) The liquid crystal aligning agent of Claim 3 whose said tetracarboxylic dianhydride contains the compound represented by a following formula (T1).

(In Formula (T1), when there are a plurality of Zs, each independently represents an oxygen atom, a sulfur atom, an ester bond, a thioester bond or —NH—;
When there are a plurality of R ^{1 s} , each independently represents an arylene group having 6 to 18 carbon atoms or an alkylene group having 2 to 6 carbon atoms; and n1 is an integer of 0 to 2. )   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. A polyamic acid obtained by reacting a tetracarboxylic dianhydride and a diamine containing a compound represented by the following formula (A1) or an imidized polymer thereof.

(In Formula (A1), two X's are each independently an oxygen atom, a sulfur atom, an ester bond, a thioester bond, an amide bond, -NH-, -C (= O)-, or a carbon number of 1-10. A divalent saturated aliphatic group or a divalent unsaturated aliphatic group having 2 to 10 carbon atoms;
A plurality of Y are each independently a single bond, oxygen atom, sulfur atom, ester bond or thioester bond;
R is a methylene group or an alkylene group having 2 to 12 carbon atoms which may be interrupted by an oxygen atom. ) A compound represented by the following formula (A1).

(In Formula (A1), two X's are each independently an oxygen atom, a sulfur atom, an ester bond, a thioester bond, an amide bond, -NH-, -C (= O)-, or a carbon number of 1-10. A divalent saturated aliphatic group or a divalent unsaturated aliphatic group having 2 to 10 carbon atoms;
A plurality of Y are each independently a single bond, oxygen atom, sulfur atom, ester bond or thioester bond;
R is a methylene group or an alkylene group having 2 to 12 carbon atoms which may be interrupted by an oxygen atom. )

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