Liquid crystal alignment agent, liquid crystal alignment film and liquid crystal display element

Abstract

To provide a manufacturing method of liquid crystal alignment agent for liquid crystal display element, the method capable of achieving a pretilt angle of the liquid crystal of substantially zero degree, thereby being suitable for a vehicle-mounted meter, a monitoring camera, a monitor for medical camera and the like requiring images having high luminance, high definition and high degree of reliability.SOLUTION: The liquid crystal alignment agent contains (A) a polymer obtained by using a monomer represented by formula (1) and (B) organic solvent.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a liquid crystal aligning agent that provides a liquid crystal alignment film suitable for use in liquid crystal display elements that require high brightness, high definition and highly reliable images, a liquid crystal alignment film, and a liquid crystal display element. [Background technology]

[0002] Liquid crystal display elements are currently widely used as thin, lightweight display devices. Liquid crystal display elements typically use a liquid crystal alignment film to determine the alignment state of the liquid crystal. With the exception of some vertical alignment type liquid crystal display elements, most liquid crystal alignment films are produced by performing some kind of alignment treatment on the surface of a polymer film formed on an electrode substrate.

[0003] Currently, the most commonly used method for aligning polymer films is a so-called rubbing treatment, in which the surface of the polymer film is rubbed with pressure using a cloth made of rayon or the like. Rubbing treatment can be performed using simple equipment and produces effective and excellent results. In addition, the drawback of the treatment, which is the generation of scraping debris from the polymer film, has been significantly improved in recent years, and therefore this method, along with the subsequent photoalignment method, is being used in a wide range of fields (see Patent Documents 1 and 2).

[0004] Meanwhile, with the recent advances in performance of liquid crystal display elements, in addition to applications such as large-screen, high-definition liquid crystal televisions, liquid crystal display elements are now being used in in-vehicle applications such as car navigation systems, meter panels, and monitors for surveillance cameras and medical cameras, etc. These applications require not only high brightness but also even higher definition and more reliable images. As one measure for this purpose, a liquid crystal alignment agent and a liquid crystal alignment film have been proposed that use a specific polymer obtained from alkylfluorenediamine, which can change the alignment direction of the liquid crystal in a liquid crystal display element from parallel to the rubbing direction to perpendicular, and can reduce the pretilt angle of the liquid crystal, which was previously as high as 1 to 10 degrees, to almost 0 degrees (see Patent Documents 3 and 4). However, in the case of a liquid crystal alignment film using a specific polymer obtained from these alkylfluorenediamines, there is still a problem in terms of the stability of the liquid crystal alignment when the liquid crystal display element is driven. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 9-185065 [Patent Document 2] Japanese Patent Application Publication No. 9-146100 [Patent Document 3] Japanese Patent Application Laid-Open No. 2002-20487 [Patent Document 4] Japanese Patent Application Laid-Open No. 2002-49039 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention aims to provide a liquid crystal alignment film suitable for use in liquid crystal display elements that require high brightness, high definition, and highly reliable images, i.e., a liquid crystal alignment film that can change the alignment direction of liquid crystals in a liquid crystal display element from a direction parallel to the rubbing direction to a direction perpendicular to the rubbing direction and can set the pretilt angle of the liquid crystal to approximately 0 degrees, and a liquid crystal aligning agent that can provide such a liquid crystal alignment film. [Means for solving the problem]

[0007] As a result of intensive research into solving the above-mentioned problems, the present inventors have found that the above-mentioned problems can be solved by using a liquid crystal aligning agent containing a polymer obtained by using a monomer having a specific structure, and by carrying out a specific treatment including a rubbing treatment in the process of producing a liquid crystal alignment film from the liquid crystal aligning agent. The present invention is based on this finding and has the following gist.

[0008] 1. A liquid crystal aligning agent comprising (A) a polymer obtained using a monomer represented by formula (1) and (B) an organic solvent. [ka] (In the formula, M represents a polymerizable unsaturated group. Q represents a single bond, a phenylene group, or a divalent alicyclic hydrocarbon group having 5 to 8 carbon atoms, and some or all of the hydrogen atoms of the phenylene group may be substituted with a cyano group, a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkylcarbonyl group having 2 to 6 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms. L is a single bond, -O-, -S-, -C(=O)-, -C(=O)-O-, -OC(=O)-, or -C(=O)-NR D -or-NR D -C(=O)-. R D represents a hydrogen atom or a methyl group. R1 to R5 each independently represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a carboxy group, provided that when there is no -C(=O)-NH- structure in M ​​when n is 0, or in M ​​or L when n is 1 or more, regardless of orientation, at least one of R1 to R5 represents a carboxy group. n is an integer of 0 to 2. When the number of Q or L is 2 or more, each Q or L may be the same or different. 2. The liquid crystal aligning agent according to claim 1, wherein in formula (1), n ​​is 0, R1 to R4 are hydrogen atoms, and R5 is a carboxy group. 3. A liquid crystal alignment film obtained by applying the liquid crystal alignment agent according to 1 or 2 above to a substrate, baking the same, and subjecting it to rubbing treatment. 4. A liquid crystal display element comprising the liquid crystal alignment film described in 3 above. [Effects of the Invention]

[0009] The liquid crystal alignment film obtained by the liquid crystal aligning agent of the present invention can change the alignment direction of the liquid crystal from parallel to the rubbing direction to perpendicular, and can make the pretilt angle of the liquid crystal nearly 0 degrees, thereby obtaining a liquid crystal display device that displays extremely high brightness, high definition, and highly reliable images. This liquid crystal display device is suitable for use in vehicles, such as car navigation systems, meter panels, and monitors for surveillance cameras and medical cameras. DETAILED DESCRIPTION OF THE INVENTION

[0010] The liquid crystal aligning agent of the present invention contains a polymer (hereinafter also simply referred to as a specific polymer) obtained using a monomer represented by formula (1), and a coating film obtained using the above polymer composition exhibits negative alignment properties even after rubbing treatment, and the pretilt angle can be made approximately 0 degrees.

[0011] In the liquid crystal aligning agent of the present invention, the monomer represented by formula (1) has no or a short spacer between the polymerizable group and the liquid crystal alignment moiety, so the direction of the alignment moiety does not change even when rubbing is performed, which is thought to be why negative alignment characteristics are exhibited. In particular, when a carboxy group is substituted on the monomer of formula (1), hydrogen bonding between the carboxy groups improves the strength of the resulting film, and when a secondary amide group is present, hydrogen bonding between the amide groups improves the strength of the resulting film. Because of these characteristics, it is thought that film strength that can withstand rubbing treatment can be achieved simply by baking at a low temperature of about 90 to 180°C. Note that this consideration does not restrict the present invention.

[0012] Hereinafter, embodiments of the present invention will be described in detail. In this specification, * represents a bond in all cases.

[0013] [Polymer composition] The liquid crystal aligning agent used in the production method of the present invention is characterized by containing (A) a polymer obtained using a monomer represented by formula (1) and (B) an organic solvent.

[0014] In the present invention, the acrylic polymer refers to a polymer obtained using a monomer having a polymerizable unsaturated group, such as an acrylic acid ester, a methacrylic acid ester, styrene, or maleimide, i.e., a polymerizable group containing a carbon-carbon double bond in the structure.

[0015] [(A) Side chain polymer] The component (A) is a polymer obtained using a monomer represented by formula (1) (hereinafter also referred to as a specific monomer). [ka] (In the formula, M represents a polymerizable unsaturated group. Q represents a single bond, a phenylene group, or a divalent alicyclic hydrocarbon group having 5 to 8 carbon atoms, and some or all of the hydrogen atoms of the phenylene group may be substituted with a cyano group, a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkylcarbonyl group having 2 to 6 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms. L is a single bond, -O-, -S-, -C(=O)-, -C(=O)-O-, -OC(=O)-, or -C(=O)-NR D -or-NR D Represents -C(=O)-. R D represents a hydrogen atom or a methyl group. R1 to R5 each independently represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a carboxy group, provided that when there is no -C(=O)-NH- structure in M ​​when n is 0, or in M ​​or L when n is 1 or more, regardless of orientation, at least one of R1 to R5 represents a carboxy group. n is an integer of 0 to 2. When the number of Q or L is 2 or more, each Q or L may be the same or different.

[0016] In formula (1), M is preferably a polymerizable group represented by any one of the following formulae (M-1) to (M-6), and more preferably a polymerizable group represented by any one of formulae (M-1) to (M-2). [ka]

[0017] In formulas (M-1) to (M-6), R 11 and R 12 each independently represents a hydrogen atom or a methyl group. The dashed line represents a bond to Q. Some of these monomers are commercially available, and others can be produced from known materials by known production methods.

[0018] The monomer represented by formula (1) is preferably a monomer selected from the group consisting of the following formulae (1-1) to (1-5). [ka] (In formulas (1-1) to (1-5), R represents a hydrogen atom or a methyl group.)

[0019] The polymer of component (A) can be obtained by polymerizing a monomer having a structure represented by formula (1).

[0020] Among these monomers, some are commercially available, and others can be produced from known materials by known production methods.

[0021] In addition, other monomers can be copolymerized to the extent that the orientation is not impaired. Examples of other monomers include industrially available radically polymerizable monomers. Specific examples of other monomers include unsaturated carboxylic acids, acrylic acid ester compounds, methacrylic acid ester compounds, maleimide compounds, acrylonitrile, maleic anhydride, styrene compounds, and vinyl compounds.

[0022] Specific examples of unsaturated carboxylic acids include acrylic acid, methacrylic acid, itaconic acid, maleic acid, and fumaric acid.

[0023] Examples of acrylic acid ester compounds include methyl acrylate, ethyl acrylate, isopropyl acrylate, benzyl acrylate, naphthyl acrylate, anthryl acrylate, anthrylmethyl acrylate, phenyl acrylate, 2,2,2-trifluoroethyl acrylate, tert-butyl acrylate, cyclohexyl acrylate, isobornyl acrylate, 2-methoxyethyl acrylate, methoxytriethylene glycol acrylate, 2-ethoxyethyl acrylate, tetrahydrofurfuryl acrylate, 3-methoxybutyl acrylate, 2-methyl-2-adamantyl acrylate, 2-propyl-2-adamantyl acrylate, 8-methyl-8-tricyclodecyl acrylate, 8-ethyl-8-tricyclodecyl acrylate, and 4-hydroxybutyl acrylate glycidyl ether.

[0024] Examples of methacrylic acid ester compounds include methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, benzyl methacrylate, naphthyl methacrylate, anthryl methacrylate, anthrylmethyl methacrylate, phenyl methacrylate, 2,2,2-trifluoroethyl methacrylate, tert-butyl methacrylate, cyclohexyl methacrylate, isobornyl methacrylate, 2-methoxyethyl methacrylate, methoxytriethylene glycol methacrylate, 2-ethoxyethyl methacrylate, tetrahydrofurfuryl methacrylate, 3-methoxybutyl methacrylate, 2-methyl-2-adamantyl methacrylate, 2-propyl-2-adamantyl methacrylate, 8-methyl-8-tricyclodecyl methacrylate, 8-ethyl-8-tricyclodecyl methacrylate, and glycidyl methacrylate.

[0025] Examples of vinyl compounds include vinyl ether, methyl vinyl ether, benzyl vinyl ether, 2-hydroxyethyl vinyl ether, phenyl vinyl ether, and propyl vinyl ether. Examples of styrene compounds include styrene, 4-methylstyrene, 4-chlorostyrene, and 4-bromostyrene. Examples of maleimide compounds include maleimide, N-methylmaleimide, N-phenylmaleimide, and N-cyclohexylmaleimide.

[0026] The content of side chains derived from the monomer represented by formula (1) in the polymer that is component (A) is preferably 5 mol % or more, more preferably 15 mol % or more, and even more preferably 30 mol % or more.

[0027] As described above, the polymer of component (A) may contain other side chains. When the content of side chains derived from the monomer represented by formula (1) is less than 100 mol %, the content of the other side chains refers to the remaining portion.

[0028] The method for producing the polymer of component (A) is not particularly limited, and a general-purpose method used industrially can be used. Specifically, the polymer can be produced by radical polymerization, cationic polymerization, or anionic polymerization using vinyl groups of the monomer represented by formula (1) above and, if desired, other monomers. Among these, radical polymerization is particularly preferred from the viewpoint of ease of reaction control, etc.

[0029] As the polymerization initiator for radical polymerization, known compounds such as radical polymerization initiators (radical thermal polymerization initiators, radical photopolymerization initiators) and reversible addition-fragmentation chain transfer (RAFT) polymerization reagents can be used.

[0030] A radical thermal polymerization initiator is a compound that generates radicals when heated to a temperature equal to or higher than its decomposition temperature. Examples of such radical thermal polymerization initiators include ketone peroxides (methyl ethyl ketone peroxide, cyclohexanone peroxide, etc.), diacyl peroxides (acetyl peroxide, benzoyl peroxide, etc.), hydroperoxides (hydrogen peroxide, tert-butyl hydroperoxide, cumene hydroperoxide, etc.), dialkyl peroxides (di-tert-butyl peroxide, dicumyl peroxide, dilauroyl peroxide, etc.), peroxyketones, etc. Examples of the radical thermal polymerization initiator include peroxyalkylene compounds (dibutylperoxycyclohexane, etc.), alkyl peresters (tert-butyl peroxyneodecanoate, tert-butyl peroxypivalate, tert-amyl peroxy-2-ethylcyclohexanoate, etc.), persulfates (potassium persulfate, sodium persulfate, ammonium persulfate, etc.), and azo compounds (azobisisobutyronitrile, 2,2'-bis(2-hydroxyethyl)azobisisobutyronitrile, dimethyl 2,2'-azobis(isobutyrate), etc.). One type of radical thermal polymerization initiator may be used alone, or two or more types may be used in combination.

[0031] The radical photopolymerization initiator is not particularly limited as long as it is a compound that initiates radical polymerization by light irradiation. Examples of such radical photopolymerization initiators include benzophenone, Michler's ketone, 4,4'-bis(diethylamino)benzophenone, xanthone, thioxanthone, isopropylxanthone, 2,4-diethylthioxanthone, 2-ethylanthraquinone, acetophenone, 2-hydroxy-2-methylpropiophenone, 2-hydroxy-2-methyl-4'-isopropylpropiophenone, 1-hydroxycyclohexylphenyl ketone, isopropyl benzoin ether, isobutyl benzoin ether, 2-hydroxy-2-methyl-4'-isopropylpropiophenone, 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-4'-isopropylpropiophenone ... ,2-Diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, camphorquinone, benzanthrone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1,4-dimethylaminobenzoic acid ethyl ester, 4-dimethylaminobenzoic acid isoamyl ester, 4,4'-bis(tert-butylperoxycarbonyl)benzophenone, 3,4,4'-tri(tert-butylperoxycarbonyl)benzophenone (dicarbonyl)benzophenone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2-(4'-methoxystyryl)-4,6-bis(trichloromethyl)-s-triazine, 2-(3',4'-dimethoxystyryl)-4,6-bis(trichloromethyl)-s-triazine, 2-(2',4'-dimethoxystyryl)-4,6-bis(trichloromethyl)-s-triazine, 2-(2'-methoxystyryl)-4,6-bis(trichloromethyl)-s-triazine, 2-(4'-pentyloxy) cisstyryl)-4,6-bis(trichloromethyl)-s-triazine, 4-[pN,N-di(ethoxycarbonylmethyl)]-2,6-di(trichloromethyl)-s-triazine, 1,3-bis(trichloromethyl)-5-(2'-chlorophenyl)-s-triazine, 1,3-bis(trichloromethyl)-5-(4'-methoxyphenyl)-s-triazine, 2-(p-dimethylaminostyryl)benzoxazole, 2-(p-dimethylaminostyryl)benzthiazole, 2-mercaptobenzothiazole, 3,3'-Carbonylbis(7-diethylaminocoumarin), 2-(o-chlorophenyl)-4,4',5,5'-tetraphenyl-1,2'-biimidazole, 2,2'-bis(2-chlorophenyl)-4,4',5,5'-tetrakis(4-ethoxycarbonylphenyl)-1,2'-biimidazole, 2,2'-bis(2,4-dichlorophenyl)-4,4',5,5'-tetraphenyl-1,2'-biimidazole, 2,2'-bis(2,4- dibromophenyl)-4,4',5,5'-tetraphenyl-1,2'-biimidazole, 2,2'-bis(2,4,6-trichlorophenyl)-4,4',5,5'-tetraphenyl-1,2'-biimidazole, 3-(2-methyl-2-dimethylaminopropionyl)carbazole, 3,6-bis(2-methyl-2-morpholinopropionyl)-9-n-dodecylcarbazole, 1-hydroxycyclohexyl phenyl ketone, bis(5-2, 4-cyclopentadien-1-yl)-bis(2,6-difluoro-3-(1H-pyrrol-1-yl)-phenyl)titanium, 3,3',4,4'-tetra(t-butylperoxycarbonyl)benzophenone, 3,3',4,4'-tetra(t-hexylperoxycarbonyl)benzophenone, 3,3'-bis(methoxycarbonyl)-4,4'-bis(tert-butylperoxycarbonyl)benzophenone, 3,4'-bis(methoxycarbonyl) Examples of the radical photopolymerization initiator include 4,4'-bis(methoxycarbonyl)-4,3'-bis(tert-butylperoxycarbonyl)benzophenone, 4,4'-bis(methoxycarbonyl)-3,3'-bis(tert-butylperoxycarbonyl)benzophenone, 2-(3-methyl-3H-benzothiazol-2-ylidene)-1-naphthalen-2-yl-ethanone, and 2-(3-methyl-1,3-benzothiazol-2(3H)-ylidene)-1-(2-benzoyl)ethanone. The radical photopolymerization initiator may be used alone or in combination of two or more.

[0032] The radical polymerization method is not particularly limited, and may be an emulsion polymerization method, a suspension polymerization method, a dispersion polymerization method, a precipitation polymerization method, a bulk polymerization method, a solution polymerization method, or the like.

[0033] The organic solvent used in the polymerization reaction is not particularly limited as long as it dissolves the produced polymer. Specific examples thereof include N,N-dimethylformamide, N,N-dimethylacetamide, N,N-diethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-methyl-ε-caprolactam, dimethyl sulfoxide, tetramethylurea, pyridine, dimethyl sulfone, hexamethylphosphoramide, γ-butyrolactone, isopropyl alcohol, methoxymethylpentanol, dipentene, ethyl amyl ketone, methyl nonyl ketone, methyl ethyl ketone, methyl isoamyl ketone, methyl isopropyl ketone, methyl cellosolve, ethyl cellosolve, methyl cellosolve acetate, ethyl cellosolve acetate, butyl carbitol, ethyl carbitol, ethylene glycol, ethylene glycol monoacetate, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, propylene glycol, and propylene glycol monoacetate. ester, propylene glycol monomethyl ether, propylene glycol tert-butyl ether, diethylene glycol, diethylene glycol monoacetate, diethylene glycol dimethyl ether, dipropylene glycol monoacetate monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monoacetate monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monoacetate monopropyl ether, 3-methyl-3-methoxybutyl acetate, tripropylene glycol methyl ether, 3-methyl-3-methoxybutanol, diisopropyl ether, ethyl isobutyl ether, diisobutylene, amyl acetate, butyl butyrate, butyl ether, diisobutyl ketone, methylcyclohexene, propyl ether, dihexyl ether, 1,4-Dioxane, n-hexane, n-pentane, n-octane, diethyl ether, cyclohexanone, ethylene carbonate, propylene carbonate, methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, n-butyl acetate, propylene glycol monoethyl ether acetate, methyl pyruvate, ethyl pyruvate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, ethyl 3-methoxypropionate, 3-ethoxypropionic acid, 3-methoxypropionic acid, propyl 3-methoxypropionate, butyl 3-methoxypropionate, diglyme, 4-hydroxy-4-methyl-2-pentanone, 3-methoxy-N,N-dimethylpropanamide, 3-ethoxy-N,N-dimethylpropanamide, 3-butoxy-N,N-dimethylpropanamide, tetrahydrofuran, cyclopentanone, cyclohexanone, etc.

[0034] The organic solvents may be used alone or in combination of two or more. Furthermore, even if the solvent does not dissolve the polymer to be produced, it may be mixed with the organic solvents described above to the extent that the polymer does not precipitate. Furthermore, since oxygen in the organic solvent inhibits the polymerization reaction in radical polymerization, it is preferable to use an organic solvent that has been degassed to the greatest extent possible.

[0035] The polymerization temperature during radical polymerization can be selected from any temperature between 30 and 150°C, but is preferably in the range of 50 to 100°C. The reaction can be carried out at any concentration, but if the concentration is too low, it becomes difficult to obtain a polymer with a high molecular weight, and if the concentration is too high, the reaction solution becomes too viscous, making uniform stirring difficult. Therefore, the monomer concentration is preferably 1 to 50% by mass, more preferably 5 to 30% by mass. The reaction can be carried out at a high concentration initially, and then an organic solvent can be added.

[0036] In the above-mentioned radical polymerization reaction, if the ratio of the radical polymerization initiator to the monomer is high, the molecular weight of the obtained polymer will be small, and if it is low, the molecular weight of the obtained polymer will be large, so the ratio of the radical initiator to the monomer to be polymerized is preferably 0.1 to 10 mol %. Furthermore, various monomer components, solvents, initiators, etc. can also be added during polymerization.

[0037] To recover the polymer produced from the reaction solution obtained by the above reaction, the reaction solution may be poured into a poor solvent to precipitate the polymer. Examples of poor solvents used for precipitation include methanol, acetone, hexane, heptane, butyl cellosolve, heptane, methyl ethyl ketone, methyl isobutyl ketone, ethanol, toluene, benzene, diethyl ether, methyl ethyl ether, and water. The polymer precipitated by pouring into the poor solvent can be recovered by filtration and then dried at room temperature or by heating under atmospheric or reduced pressure. Furthermore, the recovered polymer can be redissolved in an organic solvent and reprecipitated and recovered 2 to 10 times to reduce the amount of impurities in the polymer. Examples of poor solvents include alcohols, ketones, and hydrocarbons. Using three or more poor solvents selected from these solvents is preferred because it further increases the efficiency of purification.

[0038] The polymer as component (A) used in the production method of the present invention preferably has a weight average molecular weight measured by GPC (Gel Permeation Chromatography) of 2,000 to 2,000,000, more preferably 2,000 to 1,000,000, and even more preferably 5,000 to 200,000, in consideration of the strength of the resulting coating film, the workability during coating film formation, and the uniformity of the coating film.

[0039] [(B) Organic solvent] The organic solvent of component (B) is not particularly limited as long as it dissolves the polymer component. Specific examples thereof include N,N-dimethylformamide, N,N-dimethylacetamide, N,N-diethylacetamide, N-methyl-2-pyrrolidone, N-methyl-ε-caprolactam, 2-pyrrolidone, N-ethyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, dimethyl sulfoxide, tetramethylurea, pyridine, dimethyl sulfone, hexamethylphosphoramide, γ-butyrolactone, 3-methoxy-N,N-dimethylpropanamide, 3-ethoxy-N,N-dimethylpropanamide, 3-butoxy-N,N-dimethylpropanamide, 1,3-dimethyl-2-imidazolidinone, ethyl amyl ketone, methyl nonyl ketone, methyl ethyl ketone, methyl isoamyl ketone, methyl isopropyl ketone, cyclohexanone, ethylene carbonate, and propylene carbonate. , diglyme, 4-hydroxy-4-methyl-2-pentanone, propylene glycol monoacetate, propylene glycol monomethyl ether, propylene glycol tert-butyl ether, diethylene glycol, diethylene glycol monoacetate, diethylene glycol dimethyl ether, dipropylene glycol monoacetate monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monoacetate monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monoacetate monopropyl ether, 3-methyl-3-methoxybutyl acetate, tripropylene glycol methyl ether, cyclopentanone, cyclohexanone, etc. These may be used alone or in combination of two or more.

[0040] [Other ingredients] The polymer composition of the present invention may contain components other than the components (A) and (B), examples of which include, but are not limited to, compounds that improve the voltage holding ratio of a liquid crystal cell, solvents or compounds that improve the film thickness uniformity and surface smoothness when the polymer composition is applied, and compounds that improve the adhesion between a liquid crystal alignment film and a substrate.

[0041] An example of a compound that improves the voltage holding ratio of a liquid crystal cell is a compound having an alkoxysilyl group and a urea structure substituted at the 1st and 3rd positions (hereinafter also referred to as compound B).

[0042] The compound is not particularly limited in structure as long as it has one or more alkoxysilyl groups and one or more 1,3-disubstituted urea structures. From the viewpoint of availability, a compound represented by the following formula (b) is one of the preferred examples. [ka] In formula (b), X is an n-valent organic group containing an aliphatic hydrocarbon group or an aromatic hydrocarbon group having 1 to 20 carbon atoms, n is an integer of 1 to 6, and R 2 represents a hydrogen atom or an alkyl group. When n is 2 or more, R 2 is another R 2 and R may form an alkylene group together with X, or when n is 1 to 6, may bond to X to form a ring structure together with X. L represents an alkylene group having 2 to 20 carbon atoms, and R 3 and R 4 are each independently an alkyl group having 1 to 4 carbon atoms, an alkenyl group having 2 to 4 carbon atoms, or an alkynyl group having 2 to 4 carbon atoms; and q represents an integer of 1 to 3.

[0043] R 2 The alkyl group includes alkyl groups having 1 to 3 carbon atoms, and a methyl group is preferred. R 3 and R 4 are each independently a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, or a sec-butyl group. In terms of availability of raw materials and reactivity, a methyl group or an ethyl group is preferred. L may be an alkylene group having 2 to 20 carbon atoms. In terms of availability of raw materials, a trimethylene group is preferred. q is preferably 2 or 3, and 3 is particularly preferred. n is preferably 1, 2 or 3, and 1 or 2 is particularly preferred.

[0044] Examples of compound B include compounds represented by any one of the following formulas (B-1) to (B-6). [ka]

[0045] In formulas (B-1) to (B-6), R each independently represents a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, or the like. From the viewpoint of procuring raw materials, a methyl group or an ethyl group is preferred, and from the viewpoint of improving the voltage holding ratio of a liquid crystal cell, a methyl group is particularly preferred.

[0046] In formula (B-1), X 1 represents a divalent organic group containing an aliphatic hydrocarbon group having 1 to 20 carbon atoms or an aromatic hydrocarbon group, and is preferably one of the structures shown below. [ka]

[0047] X 1 Among these, the structure represented by any one of the following is particularly preferred. [ka]

[0048] In formula (B-2), X 2 represents a divalent organic group having 1 to 20 carbon atoms, which has two or more nitrogen atoms forming an alicyclic structure, and is preferably one of the structures shown below. For convenience, the following structural formula is written including the nitrogen atom in the ring. [ka]

[0049] In formula (B-3), X 3 represents a divalent organic group having 1 to 20 carbon atoms, which has one or more nitrogen atoms forming an alicyclic structure, and is preferably one of the structures shown below. For convenience, the following structural formula is written including the nitrogen atom in the ring. [ka]

[0050] In formula (B-4), X 4 represents an aliphatic hydrocarbon group having 1 to 20 carbon atoms or a trivalent organic group containing an aromatic hydrocarbon group, and is preferably any of the structures shown below. [ka]

[0051] In formula (B-5), X 5 represents a monovalent organic group containing an aliphatic hydrocarbon group having 1 to 20 carbon atoms or an aromatic hydrocarbon group, and is preferably one of the structures shown below. [ka]

[0052] In formula (B-6), X 6 represents a monovalent organic group having 1 to 20 carbon atoms, which has one or more nitrogen atoms forming an alicyclic structure, and is preferably one of the structures shown below. For convenience, the following structural formula is written including the nitrogen atom in the ring. [ka]

[0053] Specific examples of compound B preferably include compounds represented by the following formulae AD-1 to AD-6. [ka]

[0054] If the compound that improves the voltage holding ratio of a liquid crystal cell is added in an amount that is too large, it will affect the liquid crystal alignment, and if the amount is too small, the effect will not be obtained. Therefore, the amount added is preferably 0.1 to 20 parts by mass, more preferably 1 to 10 parts by mass, relative to 100 parts by mass of the total amount of the polymer that is the component (A) contained in the liquid crystal alignment agent.

[0055] Specific examples of solvents (poor solvents) that improve the uniformity of the film thickness and the surface smoothness include isopropyl alcohol, methoxymethyl pentanol, methyl cellosolve, ethyl cellosolve, butyl cellosolve, methyl cellosolve acetate, ethyl cellosolve acetate, butyl carbitol, ethyl carbitol, ethyl carbitol acetate, ethylene glycol, ethylene glycol monoacetate, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, propylene glycol, propylene glycol monomethyl ether, propylene glycol-tert-butyl ether, diethylene glycol, diethylene glycol monoacetate, diethylene glycol dimethyl ether, dipropylene glycol monoacetate monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monoacetate monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monoacetate monopropyl ether, and 3-methyl-3-methoxybutyl ether. Acetate, tripropylene glycol methyl ether, 3-methyl-3-methoxybutanol, diisopropyl ether, ethyl isobutyl ether, diisobutylene, amyl acetate, butyl butyrate, butyl ether, diisobutyl ketone, methylcyclohexene, propyl ether, dihexyl ether, 1-hexanol, n-hexane, n-pentane, n-octane, diethyl ether, methyl lactate, ethyl lactate, n-propyl lactate, n-butyl lactate, isoamyl lactate, methyl acetate, ethyl acetate, n-butyl acetate, propyl acetate Pyrene glycol monoethyl ether, methyl pyruvate, ethyl pyruvate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, ethyl 3-methoxypropionate, 3-ethoxypropionic acid, 3-methoxypropionic acid, propyl 3-methoxypropionate, butyl 3-methoxypropionate, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, 1-butoxy-2-propanol, 1-phenoxy-2-propanol, propylene glycol monoacetate, propylene glycol diacetate,Examples of solvents having low surface tension include propylene glycol-1-monomethyl ether-2-acetate, propylene glycol-1-monoethyl ether-2-acetate, dipropylene glycol, and 2-(2-ethoxypropoxy)propanol.

[0056] These poor solvents may be used alone or in combination of two or more. When the poor solvent is used, its content in the solvent is preferably 5 to 80% by mass, more preferably 20 to 60% by mass, so as not to significantly reduce the solubility of all the solvents contained in the polymer composition.

[0057] Compounds that improve film thickness uniformity and surface smoothness include fluorine-based surfactants, silicone-based surfactants, and nonionic surfactants. Specific examples include EFTOP (registered trademark) 301, EF303, and EF352 (manufactured by Tochem Products Co., Ltd.), MEGAFACE (registered trademark) F171, F173, F560, F563, R-30, R-40, and R-41 (manufactured by DIC Corporation), Fluorad FC430 and FC431 (manufactured by 3M Limited), Asahiguard (registered trademark) AG710 (manufactured by AGC Corporation), and Surflon (registered trademark) S-382, SC101, SC102, SC103, SC104, SC105, and SC106 (manufactured by AGC Seimi Chemical Co., Ltd.). The content of these surfactants is preferably 0.01 to 2 parts by mass, and more preferably 0.01 to 1 part by mass, per 100 parts by mass of component (A).

[0058] Specific examples of compounds that improve the adhesion between the liquid crystal alignment film and the substrate include functional silane-containing compounds, and specific examples thereof include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 2-aminopropyltrimethoxysilane, 2-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-ureidopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, N-ethoxycarbonyl-3-aminopropyltrimethoxysilane, and N-ethoxycarbonyl-3-aminopropyltrimethoxysilane. Examples of the silane include triethoxysilane, N-(3-triethoxysilyl)propyltriethylenetetramine, N-(3-trimethoxysilyl)propyltriethylenetetramine, 10-trimethoxysilyl-1,4,7-triazadecane, 10-triethoxysilyl-1,4,7-triazadecane, 9-trimethoxysilyl-3,6-diazanonyl acetate, 9-triethoxysilyl-3,6-diazanonyl acetate, N-benzyl-3-aminopropyltrimethoxysilane, N-benzyl-3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, and N-phenyl-3-aminopropyltriethoxysilane.

[0059] Furthermore, in order to improve the adhesion between the substrate and the retardation material and to prevent deterioration of characteristics due to backlight when a polarizing plate is constructed, a phenoplast compound or an epoxy group-containing compound may be added to the polymer composition.

[0060] Specific examples of phenoplast additives are shown below, but are not limited to these. [ka]

[0061] Specific examples of epoxy group-containing 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, 2,2-dibromoneopentyl glycol diglycidyl ether, 1,3,5,6-tetraglycidyl-2,4-hexanediol, N,N,N',N'-tetraglycidyl-m-xylylenediamine, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, and N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenylmethane.

[0062] When a compound that improves adhesion to the substrate is used, the content thereof is preferably 0.1 to 30 parts by mass, and more preferably 1 to 20 parts by mass, per 100 parts by mass of the polymer component contained in the polymer composition. If the content is less than 0.1 part by mass, the effect of improving adhesion cannot be expected, and if it is more than 30 parts by mass, the alignment of the liquid crystal may be deteriorated.

[0063] In addition to the above, the polymer composition of the present invention may contain a dielectric or conductive substance for the purpose of changing the electrical properties such as the dielectric constant or conductivity of the liquid crystal aligning agent, and further may contain a crosslinkable compound for the purpose of increasing the hardness and density of the film when made into a liquid crystal alignment film, as long as the effects of the present invention are not impaired.

[0064] [Preparation of polymer composition] The polymer composition of the present invention is preferably prepared as a coating liquid suitable for forming a liquid crystal alignment film. That is, the polymer composition used in the present invention is preferably prepared as a solution in which component (A), the solvent or compound that improves the film thickness uniformity and surface smoothness described above, and the compound that improves the adhesion between the liquid crystal alignment film and the substrate, etc. are dissolved in component (B) as an organic solvent. Here, the content of component (A) in the composition of the present invention is preferably 1 to 30 mass %, more preferably 5 to 30 mass %.

[0065] The polymer composition of the present invention may contain other polymers in addition to the polymer of component (A) as long as the liquid crystal alignment property is not impaired. In this case, the content of the other polymers in the polymer component is preferably 0.5 to 80 mass %, more preferably 1 to 50 mass %. Examples of the other polymers include polymers such as poly(meth)acrylate, polyamic acid, and polyimide obtained without using the monomer of formula (1).

[0066] The liquid crystal aligning agent of the present invention obtained as described above can be applied to a substrate, dried and baked to form a film, and the film surface can be subjected to an alignment treatment by rubbing to be used as a liquid crystal alignment film.

[0067] The substrate on which the liquid crystal alignment agent is applied is not particularly limited as long as it is highly transparent, and a glass substrate, etc., can be used. In addition, in a reflective liquid crystal display element, an opaque material such as a silicon wafer can be used for only one substrate, and in this case, a light-reflecting material such as aluminum can be used for the electrode.

[0068] Examples of methods for applying the liquid crystal aligning agent include spin coating, printing, and inkjet printing. However, from the viewpoint of productivity, transfer printing methods such as flexographic printing are widely used industrially, and are also preferably used for the liquid crystal aligning agent of the present invention. In addition, the liquid crystal aligning agent is preferably used after filtering through a membrane filter having a pore size of 0.1 μm to 1 μm.

[0069] Although a drying step is not necessarily required after applying the liquid crystal alignment agent, it is preferable to include a drying step when the time from application to baking is not constant for each substrate or when baking is not performed immediately after application. This drying step is sufficient as long as the solvent is evaporated to an extent that the coating film shape does not deform due to transportation of the substrate, and the drying method is not particularly limited. Specifically, a method of drying on a hot plate at 50 to 150°C, preferably 60 to 120°C, for 0.5 to 30 minutes, preferably 1 to 5 minutes, is used.

[0070] The baking after coating the liquid crystal alignment agent can be carried out at any temperature between 50 and 350° C., preferably between 60 and 200° C., and more preferably between 90 and 180° C. This baking can be carried out using a hot plate, a hot air circulating oven, an infrared oven, or the like.

[0071] The thickness of the coating after firing is preferably 5 to 300 nm, more preferably 10 to 100 nm, since if it is too thick it will be disadvantageous in terms of power consumption of the liquid crystal display element, and if it is too thin it may reduce the reliability of the liquid crystal display element.

[0072] The material of the rubbing cloth used in the rubbing treatment may be cotton, nylon, rayon, or the like.

[0073] The liquid crystal display element of the present invention is obtained by obtaining a substrate with a liquid crystal alignment film from the liquid crystal aligning agent of the present invention by the above-mentioned method, and then preparing a liquid crystal cell by a known method to obtain a liquid crystal display element.

[0074] Examples of methods for producing a liquid crystal cell include preparing a pair of substrates each having a liquid crystal alignment film, spraying spacers onto the liquid crystal alignment film of one substrate, attaching the other substrate with the liquid crystal alignment film facing inward, and injecting liquid crystal under reduced pressure to seal the cell, or dropping liquid crystal onto the liquid crystal alignment film surface sprayed with spacers, and then attaching the substrates together to seal the cell. The thickness of the spacer in this case is preferably 1 to 30 μm, more preferably 2 to 10 μm. [Example]

[0075] The present invention will be described in more detail below with reference to Synthesis Examples, Preparation Examples, Examples, and Comparative Examples, but the present invention is not limited to the following Examples. The abbreviations of the compounds used and the methods for measuring the respective physical properties are as follows.

[0076] (monomer) M-1 to M-6: Compounds represented by the following formulas (M-1) to (M-6), respectively [ka] Of the above monomers, M-1 to M-3 are included in the range of specific monomers.

[0077] (additives) AD-1 to AD-3: Compounds represented by the following formulae (AD-1) to (AD-3), respectively [ka]

[0078] (organic solvent) THF: tetrahydrofuran DMF: N,N-dimethylformamide DEAc: N,N-diethylacetamide DMSO: dimethyl sulfoxide NMP: N-methyl-2-pyrrolidone BCS: Butyl cellosolve (Polymerization initiator) AIBN: 2,2'-azobisisobutyronitrile (Other reagents) TEA: Triethylamine BHT: Dibutylhydroxytoluene

[0079] <Molecular weight measurement> The molecular weight of the polymer was measured by a GPC (room temperature gel permeation chromatography) device, and the number average molecular weight (Mn) and weight average molecular weight (Mw) were calculated as polyethylene glycol and polyethylene oxide equivalent values. GPC device: GPC-101 (manufactured by Resonac) Column: GPC KD-803, GPC KD-805 (Resonac) in series Column temperature: 50℃ Eluent: N,N-dimethylformamide (additives: lithium bromide monohydrate (LiBr·HO) 30 mmol / L, phosphoric acid anhydrous crystal (o-phosphoric acid) 30 mmol / L, tetrahydrofuran (THF) 10 ml / L) Flow rate: 1.0ml / min Standard sample for preparing a calibration curve: EasiVial PEG / PEO polyethylene glycol oxide PL2080-0201 (molecular weight: approximately 1,500, approximately 4,000, approximately 13,000, approximately 30,000, approximately 70,000, approximately 130,000, approximately 500,000, approximately 1,000,000, approximately 1,500,000) (GL Sciences)

[0080] [Synthesis of Monomers and Additives] M-3 was synthesized according to the method described in the Chinese publication (CN113387831A). M-2, M-6, AD-1 and AD-2 are new compounds not yet published in the literature, and their synthesis methods are described in detail below. 1 The product was identified by H-NMR analysis (analysis conditions are as follows). Equipment: BRUKER ADVANCE III-500MHz Measurement solvent: deuterated dimethyl sulfoxide (DMSO-d6) Reference material: tetramethylsilane (TMS) (δ 0.0 ppm for 1 H)

[0081] (Monomer Synthesis Example 1: Synthesis of M-2) [ka] (1st step) A 100 mL four-neck flask was charged with o-Toluidine (10.0 g, 93.3 mmol), TEA (14.2 g, 140 mmol), and THF (50 g). Under ice-cooling and stirring, a solution of 4-Nitrobenzoyl Chloride (26.0 g, 140 mmol) diluted with THF (130 g) was added dropwise, followed by stirring at room temperature for 18 hours. The reaction mixture was then mixed with water (900 g) to precipitate a white solid, which was then filtered off. The filtered solid was dissolved in ethyl acetate (360 g), washed three times with water (250 g), dehydrated over magnesium sulfate, and the solvent was removed under reduced pressure to obtain compound (M-2a) (yield: 20.8 g, 81.2 mmol, yield: 87%, properties: white solid). (2nd process) A 100 mL four-neck flask was charged with the above-obtained M-2a (15.0 g, 58.5 mmol), carbon-supported palladium (10% Pd carbon powder (wet), K-type, N.E. Chemcat, 1.5 g), and thoroughly degassed DMF (150 g). The system was filled with hydrogen gas and stirred at room temperature for 24 hours. After confirming the disappearance of the starting material spots by thin-layer chromatography, the carbon-supported palladium was removed by filtration. The mixture was mixed with water (750 g) to precipitate a white solid, which was then filtered off. The filtered solid was dissolved in ethyl acetate (150 g), washed three times with water (80 g), dehydrated over magnesium sulfate, and the solvent was evaporated under reduced pressure to give compound (M-2b) (yield: 11.2 g, 49.5 mmol, 85%, physical properties: white solid). (3rd step) A 100 mL four-neck flask was charged with the above-obtained M-2b (10.0 g, 44.2 mmol), TEA (6.71 g, 66.3 mmol), and THF (320 g). Methacryloyl chloride (5.54 g, 53.0 mmol) was added dropwise under ice-cooling and stirring, and the mixture was stirred at room temperature for 18 hours. The reaction mixture was then replaced with ethyl acetate (300 g), washed four times with water (80 g), dehydrated over magnesium sulfate, and the solvent was removed under reduced pressure to obtain compound (M-2) (yield: 9.80 g, 33.3 mmol, yield: 75%, properties: white solid). 1 H-NMR(500MHz) in DMSO-d6:δ(ppm)=9.92(s,1H),9.54(s,1H),7.80(m,4H),7.10-7.30(m,4H),5.80(s,1H),5.72(s,1H),2.20(s,3H),2.0(s,3H).

[0082] (Monomer Synthesis Example 2: Synthesis of M-6) [ka] (1st step) A 100 mL four-neck flask was charged with 4-aminobenzanilide (10.0 g, 47.1 mmol), TEA (7.15 g, 70.7 mmol), and THF (180 g). Under ice-cooling and stirring, 5-chlorovaleryl chloride (7.30 g, 47.1 mmol) was added dropwise, followed by stirring at room temperature for 18 hours. The reaction mixture was then mixed with water (900 g) to precipitate a white solid, which was then filtered off. The filtered solid was dissolved in ethyl acetate (360 g), washed three times with water (250 g), dehydrated over magnesium sulfate, and the solvent was removed under reduced pressure to obtain compound (M-6a) (yield: 13.1 g, 39.6 mmol, yield: 84%, properties: white solid). (2nd process) A 100 mL four-neck flask was charged with the above-obtained M-2a (10.0 g, 30.2 mmol), KI (0.502 g, 3.02 mmol), BHT (0.665 g, 3.02 mmol), potassium methacrylate (4.50 g, 36.3 mmol), and DMF (150 g), and the mixture was stirred at 80 ° C. for 18 hours. The reaction solution was then replaced with ethyl acetate (300 g), washed four times with water (80 g), dehydrated with magnesium sulfate, and the solvent was removed under reduced pressure to obtain compound (M-6) (yield: 8.10 g, 21.3 mmol, yield: 70%, properties: white solid). 1 H-NMR(500MHz) in DMSO-d6:δ(ppm)=10.2(s,1H),10.0(s,1H),7.80-7.84(t,4H),7.70(d,2H),7.32(t,2H),7.0 5(t,1H),6.48(s,1H),6.40(s,1H),4.00(t,2H),2.35(t,2H),2.01(a,3H),1.60-1.64(m,4H).

[0083] (Additive Synthesis Example 1: Synthesis of AD-1) [ka] THF (40.0 g) was added to 4,4'-diaminodiphenylamine (5.00 g, 25.1 mol) and stirred while cooling in an ice bath (0 °C). (3-Isocyanatopropyl)trimethoxysilane (10.6 g, 51.6 mol) was added dropwise, and the mixture was stirred at room temperature (25 °C) for 23 hours after the dropwise addition. The precipitated crystals were filtered off and dried to obtain crude AD-1. Methanol (45 g) was added to the crude mixture, and the mixture was heated and stirred at 50 °C for 1 hour and cooled to room temperature (25 °C). The precipitated crystals were filtered off and dried under reduced pressure to obtain AD-1 (yield: 12.0 g, 19.7 mol, yield: 78%, white powder). 1 H-NMR(500MHz) in DMSO-d6:δ(ppm)=8.08(s,2H),7.57(s,1H),7.20(d,J=8.5Hz,4H),6.87(d,J=9.0Hz,4H ),6.01(t,2H),3.48(s,18H),3.05-3.01(m,4H),1.49-1.45(m,4H),0.60-0.56(m,4H).

[0084] (Additive Synthesis Example 2: Synthesis of AD-2) [ka] A 100 mL four-neck flask was charged with 1,3-diaminobenzene (2.16 g, 20.0 mmol) and THF (30 g). A solution of (3-isocyanatopropyl)trimethoxysilane (9.03 g, 44.0 mmol) diluted with THF (5 g) was added dropwise over 1 hour with ice cooling and stirring, followed by stirring at room temperature for 18 hours. The precipitated crystals were then filtered off and transferred to another 300 mL recovery flask. Methanol (50 g) was then added to the flask and the mixture was stirred at room temperature for a while. The precipitated crystals were filtered off and dried under reduced pressure to obtain compound (AD-2) (yield: 8.30 g, 16.0 mmol, yield: 80%, properties: white solid). 1H-NMR(500MHz) in DMSO-d6:δ(ppm)=8.32(s,2H),7.45(s,1H),7.04-6.93(m,3H),6.06(t,J=5.4H z,2H),3.48(s,18H),3.06-3.02(m,4H),1.50-1.44(m,4H),0.60-0.57(m,4H).

[0085] [Polymer synthesis] (Synthesis Example 1) M-1 (4.124 g, 20.0 mmol) and AIBN (0.099 g, 0.60 mmol) were dissolved in NMP (16.9 g) to prepare a monomer mixture solution with a concentration of 20.0 mass%. The monomer mixture solution was reacted at 60°C for 12 hours under a nitrogen atmosphere. After the reaction was completed, the reaction solution was poured into pure water, and the polymer was precipitated. The polymer was filtered and washed with a 3:1 water:methanol mixture to obtain polymer powder P-1 (3.0 g). The Mn of this polymer was 37,028 and the Mw was 88,528.

[0086] (Synthesis Examples 2 to 11) Except for changing the monomers used, polymer powders P-2 to P-11 were obtained in the same manner as in Synthesis Example 1. The types and amounts of monomers and polymerization initiators used in each polymer polymerization, as well as the molecular weights of the obtained polymers, are shown in Table 1.

[0087] Table 1. [Table 1]

[0088] [Preparation of liquid crystal alignment agent] (Preparation Example 1) NMP (10.7 g) and BCS (5.00 g) were added to the polymer powder P-1 (1.0 g) obtained in Synthesis Example 1 and stirred at room temperature (25° C.) to obtain a polymer solution AL-1. The obtained AL-1 was used as a liquid crystal alignment agent as it was.

[0089] (Preparation Examples 2 to 11) As shown in Table 2, polymer solutions AL-2 to AL-8 and AL-C1 to AL-C3 were obtained by carrying out the same procedure as in Preparation Example 1, except that the polymer powder used was replaced from P-1 to P-2 to P-11. The obtained AL-2 to AL-8 and AL-C1 to AL-C3 were used as liquid crystal alignment agents as they were.

[0090] (Preparation Example 12) DEAc (10.7 g) and BCS (5.00 g) were added to the polymer powder P-1 (1.0 g) obtained in Synthesis Example 1 and stirred at room temperature to obtain a polymer solution AL-9. The obtained AL-9 was used as a liquid crystal alignment agent as it was.

[0091] (Preparation Example 13) Polymer powder P-9 (0.5 g) obtained in Synthesis Example 9, NMP (10.7 g), and BCS (5.00 g) were added to polymer powder P-2 (0.50 g) obtained in Synthesis Example 2, and the mixture was stirred at room temperature to obtain polymer solution AL-10. The obtained AL-10 was used as a liquid crystal alignment agent as it was.

[0092] (Preparation Example 14) NMP (10.7 g) and BCS (5.00 g) were added to the polymer powder P-1 (1.0 g) obtained in Synthesis Example 1 and stirred, and then additive AD-1 (0.050 g, 5% by mass based on the polymer) was added and stirred at room temperature until dissolved, to obtain polymer solution AL-11. The obtained AL-11 was used as a liquid crystal alignment agent.

[0093] (Preparation Examples 15-16) Polymer solutions AL-12 to AL-13 were obtained by preparing polymer solutions in the same manner as in Preparation Example 14, except that the additives were changed from AD-1 to AD-2 to AD-3, respectively, as shown in Table 2. The obtained AL-12 to AL-13 were used as liquid crystal alignment agents as they were.

[0094] The specifications of the liquid crystal aligning agent obtained above are shown in Table 2. In Table 2, the parenthesized numbers for polymers indicate the blending amount (parts by mass) of each polymer relative to 100 parts by mass of the total amount of polymers contained in the liquid crystal aligning agent. The parenthesized numbers for additives indicate the blending amount (parts by mass) of each additive relative to 100 parts by mass of the total amount of polymers contained in the liquid crystal aligning agent. The parenthesized numbers for solvent composition indicate the amount (parts by mass) of each solvent relative to 100 parts by mass of the liquid crystal aligning agent.

[0095] Table 2. [Table 2]

[0096] [Alignment film characteristic evaluation] (Examples 1 to 13, Comparative Examples 1 to 3) <Fabrication of liquid crystal cells> First, a substrate with electrodes was prepared. The substrate was a glass substrate measuring 30 mm x 40 mm and 0.7 mm thick. ITO electrodes with a film thickness of 175 nm were formed on the substrate, and the electrodes were in a stripe pattern spaced 40 mm vertically and 10 mm horizontally. Next, the liquid crystal alignment agents AL-1 to AL-13 and AL-C1 to AL-C3 obtained above were each filtered through a 1.0 μm pore size filter and then spin-coated onto the electrode-attached substrate prepared above. The resulting substrate was then dried on a hot plate at 60°C for 2 minutes and baked on a hot plate at 90 to 120°C (the temperature indicated in the "Baking Temperature" column in Table 3) for 5 minutes to form a 100 nm-thick coating film, yielding a substrate with a liquid crystal alignment film. This liquid crystal alignment film was subjected to a rubbing alignment treatment (roller diameter: 120 mm, roller rotation speed: 1000 rpm, movement speed: 20 mm / sec, indentation length: 0.4 mm) using a rayon cloth (Yoshikawa Chemical Industry Co., Ltd., YA-20R). The substrate was then ultrasonically washed in pure water for 1 minute, water droplets were removed by air blowing, and the substrate was then dried at 80°C for 10 minutes to obtain a substrate with a liquid crystal alignment film. Two substrates with this liquid crystal alignment film were prepared. Spherical spacers with a particle size of 4 μm were sprayed onto the liquid crystal alignment film surface of one substrate. A sealant (Mitsui Chemicals XN-1500T) was then printed around the periphery, leaving the liquid crystal injection port. The other substrate was then attached, with the rubbing direction perpendicular to the 90° angle and the film surfaces facing each other. The substrate was then heated at 120°C for 90 minutes to harden the sealant, producing an empty cell. Negative liquid crystal MLC-7026-100 (Merck) was injected into the empty cell by a vacuum injection method, and the injection port was sealed to obtain a liquid crystal cell. The resulting liquid crystal cell was then heated at 120°C for 50 minutes and left overnight at 23°C before being used for various evaluations.

[0097] <Measurement of liquid crystal alignment direction and pretilt angle> The liquid crystal alignment direction and pretilt angle in the above liquid crystal cell were measured using an AxoScan Mueller matrix polarimeter manufactured by Optometrics. Regarding the liquid crystal alignment direction, when the rubbing direction and the liquid crystal alignment direction were parallel, it was judged to be "positive" alignment, and when the rubbing direction and the liquid crystal direction were perpendicular, it was judged to be "negative" alignment. It is known that in display elements where the liquid crystal is oriented in the in-plane direction, light leakage can be reduced and display quality can be improved by bringing the pretilt angle closer to 0°. The results are shown in Table 3.

[0098] <Display quality evaluation> The liquid crystal alignment state of the liquid crystal cell prepared above was observed by sandwiching it between two polarizing plates. When the liquid crystal cell was set so that black was displayed, the liquid crystal alignment was confirmed and there was no light leakage due to flow alignment or alignment defects caused by scraping of the liquid crystal alignment film. The evaluation was performed by defining "good" as a result. The evaluation was performed by defining "poor" as a result of no confirmed alignment or visible light leakage due to scraping debris of the alignment film or tilt of the liquid crystal. The results are shown in Table 3.

[0099] <Evaluation of Voltage Holding Ratio (VHR)> A voltage of 1V was applied to the above liquid crystal cell at room temperature for 60 μs, and the voltage was measured after 500 msec. The voltage retention rate was calculated to determine how long the voltage could be maintained. The higher the voltage retention rate, the better the performance. It is known that an increase in the voltage retention rate, which is one of the electrical properties of liquid crystal display elements, makes line burn-in, a display defect of liquid crystal display elements, less likely to occur. The results are shown in Table 3.

[0100] Table 3. [Table 3]

[0101] As is clear from the table, by using the liquid crystal alignment agents shown in Examples 1 to 13, the liquid crystal was aligned perpendicular to the rubbing direction, and the pretilt angle became 0°, resulting in a liquid crystal display element with good display quality. Furthermore, as shown in Examples 11 to 13, by adding a crosslinkable additive to the liquid crystal alignment agent, the VHR could be improved without impairing the display quality.

Claims

1. A liquid crystal aligning agent comprising (A) a polymer obtained using a monomer represented by formula (1) and (B) an organic solvent. 【Chemical 1】 (In the formula, M represents a polymerizable unsaturated group. Q represents a single bond, a phenylene group, or a divalent alicyclic hydrocarbon group having 5 to 8 carbon atoms, and some or all of the hydrogen atoms of the phenylene group may be substituted with a cyano group, a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkylcarbonyl group having 2 to 6 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms. L is a single bond, —O—, —S—, —C(═O)—, —C(═O)—O—, —O—C(═O)—, or —C(═O)—NR Ｄ -or-NR Ｄ represents —C(═O)—. Ｄ represents a hydrogen atom or a methyl group. R １ ~R ５ each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a carboxy group. However, when n is 0, and when n is 1 or more, and when there is no -C(=O)-NH- structure in M ​​or in M ​​or L, regardless of the orientation, R １ ~R ５ At least one of these represents a carboxy group. n is an integer of 0 to 2. When the number of Q or L is 2 or more, each Q or L may be the same or different.

2. In formula (1), n ​​is 0 and R １ ~R ４ is a hydrogen atom, and R ５ The liquid crystal aligning agent according to claim 1, wherein is a carboxy group.

3. A liquid crystal alignment film obtained by applying the liquid crystal aligning agent according to claim 1 or 2 to a substrate, baking the same, and subjecting the same to rubbing treatment.

4. A liquid crystal display device comprising the liquid crystal alignment film according to claim 3.

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