TWI870426B - Liquid crystal alignment agent, liquid crystal alignment film and liquid crystal display element using the same - Google Patents

Abstract

The present invention provides a liquid crystal alignment agent, which can obtain a liquid crystal alignment film that can maintain a high voltage retention rate and has excellent reproducibility. The liquid crystal alignment agent is characterized by containing the following (A) components and (B) components. (A) component: at least one polymer selected from the group consisting of polyimide polymers, polyorganosiloxanes, polymers of monomers having polymerizable unsaturated bonds, and cellulose polymers. (B) component: a compound having any of a structure or a steroid skeleton having two or more rings connected directly or via a linking group, and having at least one group represented by the following formulas (b-1) to (b-5), or having at least two groups represented by the following formula (b-6), and having a molecular weight of less than 2000. (However, R ₂ , R _4a , R _4b , R ₅ and R ₆ each independently represent a hydrogen atom or an alkyl group having 1 to 20 carbon atoms. * represents a bonding hand).

Description

Liquid crystal alignment agent, liquid crystal alignment film and liquid crystal display element using the same

The present invention relates to a liquid crystal alignment agent, a liquid crystal alignment film and a liquid crystal display element using the same.

For liquid crystal display elements, various driving methods with different electrode structures, physical properties of liquid crystal molecules used, and manufacturing steps are being developed. For example, there are known liquid crystal display elements such as TN (twisted nematic) type, STN (super-twisted nematic) type, VA (vertical Alignment) type, MVA (multi-domain vertical Alignment) type, IPS (in-plane switching) type, FFS (fringe field switching) type, PSA (polymer-Sustained Alignment) type. These liquid crystal display elements are equipped with a liquid crystal alignment film in order to align the liquid crystal molecules. The material of the liquid crystal alignment film generally uses a film made of polymers such as polyamide, polyimide, and polysiloxane because of its good properties such as heat resistance, mechanical strength, and affinity with liquid crystal.

In recent years, the demand for high-quality liquid crystal display elements has been increasing. For example, a liquid crystal display element that is expected to have good liquid crystal alignment and can maintain a high voltage retention rate is disclosed in Patent Documents 1 and 2 as a liquid crystal alignment agent containing specific compounds. [Prior Technical Documents] [Patent Documents]

[Patent document 1] International Publication (WO) No. 2016/063834 [Patent document 2] Japanese Patent Publication No. 2016-200798

[Problem solved by the invention]

Furthermore, the economic efficiency of the production process of liquid crystal display elements is also very important, so the recycling of element substrates is particularly required. That is, after forming a liquid crystal alignment film on the substrate of the element using a liquid crystal alignment agent, the alignment is inspected, and if a defect is found, the liquid crystal alignment film is removed from the substrate, and the substrate is recovered and reused. A technology that can easily implement the so-called recycling process is desired.

The liquid crystal alignment agents proposed in the past are not able to fully satisfy the above-mentioned problems. The present invention is based on the above-mentioned matters, and the purpose is to provide a liquid crystal alignment agent that can obtain a liquid crystal alignment film with excellent reproducibility while maintaining a high voltage retention rate, a liquid crystal alignment film obtained therefrom, and a liquid crystal display element using the same. [Means for solving the problem]

The inventors of the present invention have conducted detailed research and found that the above-mentioned problems can be solved by using a liquid crystal alignment agent containing specific multiple components, thereby completing the present invention.

The present invention has the following gist. A liquid crystal alignment agent containing the following (A) component and (B) component is used as a specific liquid crystal alignment agent. (A) component: at least one polymer (A) selected from the group consisting of polyimide polymers (A-1), polyorganosiloxane (A-2), polymers of monomers having polymerizable unsaturated bonds (A-3) and cellulose polymers (A-4). (B) component: a compound having a structure having two or more rings connected directly or via a linking group or a steroid skeleton, having at least one group represented by the following formulas (b-1) to (b-5), or having at least two groups represented by the following formula (b-6), and having a molecular weight of 2000 or less. (* represents a bonding pair, and R ₂ , R _4a , R _4b , R ₅ , and R ₆ each independently represent a hydrogen atom or an alkyl group having 1 to 20 carbon atoms). [Effects of the Invention]

According to the liquid crystal alignment agent of the present invention, a liquid crystal display element capable of maintaining a high voltage holding rate and a liquid crystal alignment film having excellent reproducibility can be obtained.

[Type of invention to be implemented] ＜(A) Component＞

The liquid crystal alignment agent of the present invention contains at least one polymer (A) selected from: a polyimide polymer (A-1) having at least one repeating unit selected from the repeating units represented by the following formula (1) and the repeating units represented by the following formula (2), a polysiloxane (A-2), a polymer (A-3) of a monomer having a polymerizable unsaturated bond, and a cellulose polymer (A-4).

<Polyimide polymer (A-1)> The polyimide polymer is preferably a polymer having at least one repeating unit selected from the group consisting of a repeating unit represented by the following formula (1) and a repeating unit represented by the following formula (2).

However, in formula (1) and formula (2), _X1 is a tetravalent organic group, and _Y1 is a divalent organic group. _R1 is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and _Z11 and _Z12 each independently represent a hydrogen atom, an alkyl group having 1 to 10 carbon atoms which may have a substituent, an alkenyl group having 2 to 10 carbon atoms which may have a substituent, an alkynyl group having 2 to 10 carbon atoms which may have a substituent, a tert-butyloxycarbonyl group, or a 9-fluorenylmethoxycarbonyl group. Specific examples of the alkyl group having 1 to 5 carbon atoms in _R1 in the above formula (2) include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, and an n-pentyl group. _R1 is preferably a hydrogen atom or a methyl group because it can be easily imidized by heating.

Specific examples of the alkyl group having 1 to 10 carbon atoms represented by Z ₁₁ and Z ₁₂ in the above formula (2) include, in addition to the specific examples of the alkyl group having 1 to 5 carbon atoms represented by R ₁ , hexyl, heptyl, octyl, nonyl, decyl, etc. Specific examples of the alkenyl group having 2 to 10 carbon atoms represented by Z ₁₁ and Z ₁₂ include, for example, ethenyl, propenyl, butynyl, etc., which may be linear or branched. Specific examples of the alkynyl group having 2 to 10 carbon atoms represented by Z ₁₁ and Z ₁₂ include ethynyl, 1-propynyl, 2-propynyl, etc.

The above Z ₁₁ and Z ₁₂ may have a substituent, and examples of the substituent include a halogen atom (fluorine atom, chlorine atom, bromine atom, iodine atom), a hydroxyl group, a cyano group, an alkoxy group, etc. From the viewpoint of less afterimage, Z ₁₁ and Z ₁₂ are preferably a hydrogen atom or a methyl group.

As the above X ₁ , there can be mentioned a tetravalent organic group derived from at least one selected from the group consisting of tetracarboxylic dianhydride, tetracarboxylic diester and tetracarboxylic diester dihalide (hereinafter collectively referred to as tetracarboxylic acid derivatives). Specific examples include aromatic tetracarboxylic dianhydride, aliphatic tetracarboxylic dianhydride, alicyclic tetracarboxylic dianhydride, or these tetracarboxylic diesters, or a tetravalent organic group derived from a tetracarboxylic diester dihalide. Y ₁ in formula (1) is a divalent organic group derived from a diamine.

Among them, aromatic tetracarboxylic dianhydride is an acid dianhydride obtained by subjecting at least one carboxyl group bonded to an aromatic ring and four carboxyl groups contained therein to intramolecular dehydration. Aliphatic tetracarboxylic dianhydride is an acid dianhydride obtained by subjecting four carboxyl groups bonded to a chain hydrocarbon structure to intramolecular dehydration. However, it is not necessary to be composed of only a chain hydrocarbon structure, and it may also have an alicyclic structure or an aromatic ring structure in the part. Alicyclic tetracarboxylic dianhydride is an acid dianhydride obtained by subjecting at least one carboxyl group bonded to an alicyclic structure and all four carboxyl groups to intramolecular dehydration. However, none of these four carboxyl groups are bonded to an aromatic ring. Furthermore, it is not necessarily composed of an alicyclic structure only, and may have a chain hydrocarbon structure or an aromatic ring structure in the portion.

From the viewpoint of obtaining a high voltage holding ratio, _X1 is preferably a tetravalent organic group selected from the group consisting of the following formulae (4a) to (4n), the following formula (5a) and the following formula (6a).

However, x and y represent a single bond, -O-, -CO-, -CO(=O)-, an alkanediyl group having 1 to 5 carbon atoms, 1,4-phenylene, -SO-, or -NRCO- (R represents a hydrogen atom or a methyl group). ^{Z 1} to Z ⁶ each independently represent a hydrogen atom, a methyl group, an ethyl group, a propyl group, a chlorine atom, or a benzene ring. j and k represent 0 or 1. m represents an integer of 1 to 5. * represents a bond.

As a preferred specific example of the above formula (4a), from the viewpoint of obtaining a high voltage holding ratio, a structure represented by any of the following formulas (4a-1) to (4a-4) can be cited.

Examples of the alkane diyl group having 1 to 5 carbon atoms in the above formulae (5a) and (6a) include methylene, ethylidene, 1,3-propanediyl, 1,4-butanediyl, 1,5-pentanediyl, etc. From the viewpoint of obtaining a high voltage holding ratio, _X1 in the above formula (1) is preferably a tetravalent organic group selected from the group consisting of the above formulae (4a) to (4h), (4j), (4l), (4m), and (4n).

From the viewpoint of obtaining a high voltage holding factor, _X1 is a tetravalent organic group selected from the group consisting of the above-mentioned formulae (4a) to (4n), (5a) and (6a), and _Y1 is a divalent organic group selected from the group consisting of the repeating unit represented by the above-mentioned formula (1) and the repeating unit represented by the above-mentioned formula (2) (hereinafter also referred to as the repeating unit (t)), and the content of the total is preferably 5 mol% or more, more preferably 10 mol% or more, and particularly preferably 20 mol% or more relative to the total repeating units.

As Y ₁ in formula (1), a divalent organic group derived from a diamine can be mentioned. For example, a divalent organic group derived from an aliphatic diamine, an alicyclic diamine or an aromatic diamine can be mentioned. If specific examples are given, as aliphatic diamines, m-xylylenediamine, ethylenediamine, 1,3-propanediamine, tetramethylenediamine, hexamethylenediamine and the like can be mentioned; as alicyclic diamines, 1,4-cyclohexanediamine, 4,4'-methylenebis(cyclohexylamine) and the like can be mentioned.

As the aromatic diamine, there can be mentioned p-phenylenediamine, 4,4'-diaminodiphenylmethane, 4,4'-diaminobenzophenone, 4,4'-diaminodiphenyl ether, 4,4'-diaminoazobenzene, 1-(4-aminophenyl)-1,3,3-trimethyl-1H-indane-5-amine, 1-(4-aminophenyl)-2,3-dihydro-1,3,3-trimethyl-1H-indane-6-amine, 2,6-diaminopyridine, 3,4-diaminopyridine, 2,4-diaminopyrimidine, 3,6-diaminocarbazole, N-methyl-3,6-diaminocarbazole, bis(4-aminophenyl)amine, N,N-bis(4-aminophenyl)amine, 1,4-Bis(4-aminophenyl)-piperazine, 4-(4-aminophenoxycarbonyl)-1-(4-aminophenyl)piperidine, 4,4'-[4,4'-propane-1,3-diylbis(piperidin-1,4-diyl)]diphenylamine, nitrogen-containing diamines such as the following formulas (z-1) to (z-19), carboxyl-containing diamines such as 3,5-diaminobenzoic acid, 2,2'-dimethyl-4,4'-diaminobiphenyl, 1,3-bis(4-aminophenoxy)benzene, 1, 4-Bis(4-aminophenoxy)benzene, bis[4-(4-aminophenoxy)phenyl]ether, 4,4'-bis(4-aminophenoxy)biphenyl, 1,3-bis(3-aminopropyl)-tetramethyldisiloxane, diamines of the following formulas (H-1) to (H-16), (H2-1) to (H2-17), (H3-1) to (H3-4), alkyl groups having 3 to 20 carbon atoms, fluoroalkyl groups having 3 to 20 carbon atoms, alkoxy groups having 3 to 20 carbon atoms, groups having a steroid skeleton having 17 to 51 carbon atoms, structures having two or more rings in the side chain connected directly or via a linking group, etc. (polycyclic structure), a diamine having a free radical initiation function represented by the following formulas (R1) to (R5), a diamine having a photopolymerizable group at the end such as 2-(2,4-diaminophenoxy)ethyl methacrylate and 2,4-diamino-N,N-diallylaniline, a diamine having a photo-alignment structure described in [0053] of WO2014/080865, a diamine having a carbon-carbon unsaturated bond described in [0057], a diamine having an azobenzene skeleton described in [0058], and a photoreactive diamine described in [0069] to [0072] of WO2012/086715.

(n represents an integer from 2 to 10).

(Boc represents tert-butoxycarbonyl. The same applies hereinafter).

(R represents a hydrogen atom, a methyl group or a tert-butoxycarbonyl group).

(R represents a hydrogen atom, a methyl group or a tert-butyloxycarbonyl group. * represents a bonding hand).

However, in the above formulae (V2-1) to (V2-13), ^Xv1 to ^Xv4 and ^Xp1 to ^Xp8 each independently represent -( _CH2 ) _a- (a is an integer of 1 to 15), -CONH-, -NHCO-, -CON( _CH3 )-, -NH-, -O-, _-CH2O- , _-CH2OCO- , -COO-, or -OCO-, and ^Xv5 represents -O-, _-CH2O- , _-CH2OCO- , -COO-, or -OCO-. ^Xv6 , ^Xv7 , and ^Xs1 to ^Xs4 each independently represent -O-, -COO-, or -OCO-. _Xa to _Xf each independently represent a single bond, -O-, -NH-, or -O-( _CH2 ) _m -O-. R ^v1 to R ^v4 and R ^1a to R ^1h each independently represent an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, or an alkoxyalkyl group having 2 to 20 carbon atoms. M represents an integer of 1 to 8.

The polyimide polymer (A-1) of the present invention can be obtained, for example, by reacting a tetracarboxylic acid derivative having the structure of X ₁ and a diamine having the structure of Y ₁ by a known method as described in WO2013/157586. The polyimide polymer (A-1) can be the tetracarboxylic acid derivative and diamine as described above, or a terminal-modified polymer obtained by using a terminal sealing agent. Examples of the terminal sealing agent include monoanhydrides such as maleic anhydride, nagic acid anhydride, phthalic anhydride, itaconic anhydride, cyclohexanedicarboxylic anhydride, 3-hydroxyphthalic anhydride, trimellitic anhydride, and any of the compounds shown in (m-1) to (m-6) below; chlorocarbonyl compounds such as di-tert-butyl dicarbonate; monoamine compounds such as aniline, 2-aminophenol, 3-aminophenol, 4-aminosalicylic acid, 5-aminosalicylic acid, 6-aminosalicylic acid, 2-aminobenzoic acid, 3-aminobenzoic acid, and 4-aminobenzoic acid; and monoisocyanate compounds such as ethyl isocyanate, phenyl isocyanate, and naphthalene isocyanate.

The usage ratio of the end sealant is preferably 40 mol parts or less, more preferably 30 mol parts or less, relative to 100 mol parts of the total diamine used.

<Polyorganosiloxane (A-2)> The polyorganosiloxane polymer (A-2) can be obtained, for example, by hydrolyzing or hydrolyzing and condensing a hydrolyzable silane compound in the presence of a preferably suitable organic solvent, water and a catalyst. The hydrolyzable silane compound used in the synthesis of the polymer (A-2) may have at least one functional group selected from the group consisting of cyclohexane and ethylene oxide in the molecule from the viewpoint of providing a high voltage retention rate to a liquid crystal display element. Specific examples of the silane compound having an oxadiazole cyclobutane group or an oxadiazole group include glycidoxymethyltrimethoxysilane, glycidoxymethyltriethoxysilane, 2-glycidoxyethyltrimethoxysilane, 2-glycidoxyethyltriethoxysilane, 3-glycidoxypropylmethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-Gusidoxypropylmethyldimethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane.

Examples of other silane compounds used in the synthesis of polymer (A-2) include alkoxysilanes such as tetramethoxysilane, methyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, and dimethyldiethoxysilane; 3-butylpropyltriethoxysilane, butylmethyltriethoxysilane, 3-aminopropyltrimethoxysilane, N-(3-cyclohexyl)triethoxysilane; Alkoxysilanes containing nitrogen and sulfur such as amino)propyl trimethoxysilane; alkoxysilanes containing unsaturated bonds such as 3-(meth)acryloxypropyl trimethoxysilane, 3-(meth)acryloxypropyl methyl dimethoxysilane, 3-(meth)acryloxypropyl methyl diethoxysilane, and vinyl triethoxysilane; trimethoxysilylpropyl succinic anhydride, etc.

When it is used as a liquid crystal alignment agent for TN-type, STN-type or vertically aligned liquid crystal display elements, or when the coating is endowed with liquid crystal alignment ability by a photoalignment method, specific groups such as liquid crystal alignment groups or photoalignment groups can be introduced into the side chains of the polymer (A-2). If the method of synthesizing a polymer (A-2) having such specific groups in the side chains can be used, there is no particular limitation, but for example, the aforementioned silane compound containing an epoxy group, or a mixture of a silane compound containing an epoxy group and other silane compounds can be hydrolyzed and condensed to synthesize a polymer having an epoxy group, and then the obtained polymer containing an epoxy group is reacted with the above-mentioned carboxylic acid having a specific group. It can be carried out according to the known method of reacting a polymer containing an epoxy group with a carboxylic acid.

As the carboxylic acid having the above-mentioned specific group, there can be cited carboxylic acids having a liquid crystal alignment group such as an alkyl group having 4 to 20 carbon atoms, a fluoroalkyl group having 4 to 20 carbon atoms, an alkoxy group having 4 to 20 carbon atoms, a group having a steroid skeleton having 17 to 51 carbon atoms, a group having a structure having two or more rings connected directly or via a linking group (polycyclic structure), and carboxylic acids having a photo-alignment group such as a cinnamic acid structure. The weight average molecular weight (Mw) of the polymer (A-2) measured by GPC in terms of polystyrene is preferably 500 to 100,000, more preferably 1,000 to 30,000, and even more preferably 1,000 to 20,000.

<Polymer (A-3) of monomers having polymerizable unsaturated bonds> The monomers used for the polymerization of the polymer (A-3) are not particularly limited as long as they have polymerizable unsaturated bonds. Examples thereof include (meth)acrylic compounds, conjugated diene compounds, aromatic vinyl compounds, maleimide compounds, etc. From the perspective of imparting a high voltage retention rate to a liquid crystal display element, the monomer used for the polymerization may have at least one functional group selected from the group consisting of an oxycyclobutane group, an ethylene oxide group, a carboxyl group, an alkoxysilane group, a cyclic carbonate group, an isocyanate group, and a protected isocyanate group in the molecule.

Examples of the monomer having an oxocyclobutane group or an oxirane group include maleimide compounds such as N-(4-glycidyloxyphenyl)maleimide and N-glycidylmaleimide; styrene compounds such as 3-(glycidyloxymethyl)styrene, 4-(glycidyloxymethyl)styrene, and 4-glycidyl-α-methylstyrene; (meth)acrylate glycidyl, α-ethylacrylate glycidyl, α-n-propyl (Meth)acrylic acid compounds such as glycidyl acrylate, α-n-butyl acrylate glycidyl, (meth)acrylate 3,4-epoxybutyl, α-ethyl acrylate 3,4-epoxybutyl, (meth)acrylate 3,4-epoxyhexylmethyl, (meth)acrylate 6,7-epoxyheptyl, α-ethyl acrylate 6,7-epoxyheptyl, acrylate 4-hydroxybutyl glycidyl ether, (meth)acrylate (3-ethyloxycyclobutane-3-yl)methyl and the like.

Examples of monomers having a carboxyl group include styrene compounds such as 3-vinylbenzoic acid and 4-vinylbenzoic acid, (meth)acrylic acid, α-ethylacrylic acid, maleic acid, fumaric acid, vinylbenzoic acid, crotonic acid, liconaconic acid, mesaconic acid, itaconic acid, 3-maleimidobenzoic acid, 3-maleimidopropionic acid, and maleic anhydride. Examples of monomers having an isocyanate group or a protected isocyanate group include 2-methacryloyloxyethyl isocyanate (Calends MOI, manufactured by Showa Denko K.K.), 2-[(3,5-dimethylpyrazolyl)carbonylamino]ethyl methacrylate (Calends MOI-BP, manufactured by Showa Denko K.K.), and the like. Examples of the monomer having an alkoxysilyl group include 3-methacryloxypropyltrimethoxysilane (Sila Ace S710, manufactured by JNC Corporation) and 3-methacryloxypropylmethyldimethoxysilane.

Furthermore, the monomer used for polymerization of the polymer (A-3) may have a photo-aligning group. Specific examples of the photo-aligning group include azobenzene-containing groups having azobenzene or its derivatives as a basic skeleton, cinnamic acid structure-containing groups having cinnamic acid or its derivatives (cinnamic acid structure) as a basic skeleton, chalcone-containing groups having chalcone or its derivatives as a basic skeleton, benzophenone-containing groups having benzophenone or its derivatives as a basic skeleton, coumarin-containing groups having coumarin or its derivatives as a basic skeleton, cyclobutane-containing structures having cyclobutane or its derivatives as a basic skeleton, etc. Among the photo-aligning groups, groups having cinnamic acid structures are preferred from the viewpoint of high sensitivity to light. As specific examples, the following formulas (3-m1) to (3-m18) can be cited.

The monomer used for the polymer (A-3) may be used in combination with a monomer not having any of the functional groups (hereinafter also referred to as other monomers). Examples of other monomers include (meth)acrylic acid compounds such as (meth)acrylic acid alkyl, (meth)acrylic acid cycloalkyl, (meth)acrylic acid benzyl, (meth)acrylic acid-2-ethylhexyl; styrene, methylstyrene, divinylbenzene; 1,3-butadiene, 2-methyl-1,3-butadiene; N-methylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide, etc.

When synthesizing the polymer (A-3), the usage ratio of the monomer having at least one functional group selected from the group consisting of cyclohexyloxybutane, ethylene oxide, carboxyl, alkoxysilyl, cyclic carbonate, isocyanate and protected isocyanate is preferably 1 mol% or more, more preferably 5 mol% or more, and even more preferably 10 mol% or more, relative to the total amount of the monomer used in the synthesis of the polymer (A-3). Moreover, when the photoalignment group described below is used in combination, the usage ratio of the monomer is preferably 90 mol% or less, and preferably 80 mol% or less. The content ratio of the monomer having a photoalignment group is preferably 10 to 99 mol %, more preferably 10 to 95 mol %, and even more preferably 20 to 90 mol % based on the total amount of monomers used in the synthesis of the polymer (A-3).

There is no particular limitation on the method for producing the polymer (A-3), and a general method used in industry can be used. Specifically, it can be produced by cationic polymerization, free radical polymerization, or negative ion polymerization of the vinyl group of the monomer. Among them, free radical polymerization is particularly preferred from the viewpoint of easy reaction control. The polymer (A-3) can be obtained, for example, by polymerizing the monomer in the presence of a polymerization initiator. As the polymerization initiator used, azo compounds such as 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), and 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile) are preferred. The proportion of the polymerization initiator used is preferably 0.01 to 30 parts by mass relative to 100 parts by mass of all monomers used in the reaction. As the organic solvent that can be used, there can be mentioned, for example, alcohols, ethers, ketones, amides, esters, hydrocarbon compounds and the like.

The polymer (A-3) preferably has a polystyrene-equivalent Mw of 1,000 to 300,000, more preferably 2,000 to 100,000, as measured by gel permeation chromatography (GPC). The molecular weight distribution (Mw/Mn) represented by the ratio of Mw to the polystyrene-equivalent number average molecular weight (Mn) measured by GPC is preferably 10 or less, more preferably 8 or less.

<Cellulose-based polymer (A-4)> Specific examples of the polymer (A-4) include polymers having a structural unit represented by the following formula (4-c). (R ¹ to R ⁶ each independently represent a hydrogen atom or a monovalent organic group. X represents an oxygen atom or a sulfur atom).

Examples of the monovalent organic group represented by R ¹ to R ⁶ include a chain alkyl group having 1 to 10 carbon atoms, an alicyclic alkyl group having 3 to 10 carbon atoms, an aromatic alkyl group having 6 to 15 carbon atoms, and a group consisting of these groups and at least one group selected from the group consisting of -CO-, -COO-, -OCO-, and -O-. From the viewpoint of availability, R ¹ to R ⁶ may be a group selected from the group consisting of the following formulae (1a) to (1m). From the viewpoint of providing a high voltage holding ratio to a liquid crystal display element, it is preferred that at least one of R ¹ to R ⁶ contains a carboxyl group. Examples thereof include the following formulae (1f), (1h), (1i), (1j) to (1m).

However, ^X7 and ^X8 represent a benzene ring or an alkyl group having 1 to 4 carbon atoms (specifically, methyl, ethyl, n-propyl, isopropyl, butyl, etc.). ^X9 , ^X10 , ^X11 , ^X12 , ^X13 and ^X14 represent a benzene ring or an alkylene group having 1 to 4 carbon atoms (specifically, methylene, ethylene, n-propylene, isopropylene, butylene, etc.). The Mn of the polymer (A-4) is preferably 100 to 500,000, more preferably 100 to 100,000, from the viewpoint of solubility in solvents or handling properties as a liquid crystal alignment agent.

<(B) component> The (B) component contained in the liquid crystal alignment agent of the present invention has a side chain structure in the molecule, so the obtained liquid crystal alignment film has a soft structure in the molecule. This can improve the solubility in the rework solvent, so the liquid crystal alignment film of the present invention has high reproducibility. In addition, since the (B) component has a hydroxyl alkyl group at the end of the molecule, a crosslinking reaction occurs between the (A) component and the (B) component, or between the (B) components, so the crosslinking density of the obtained liquid crystal alignment film can be increased. This result shows that since the impurity components from the substrate become easy to enter the liquid crystal alignment film, the liquid crystal display element having this shows a high voltage retention rate. When component (B) has at least one group represented by any one of the above formulae (b-1) to (b-5), from the perspective of providing a high voltage retention ratio to a liquid crystal display element, it may have at least two groups represented by any one of the above formulae (b-1) to (b-5).

As the component (B), there can be mentioned compounds represented by the following formula (3-1) or the following formula (3-2).

However, _B1 represents a structure selected from the group consisting of the following formulae (b-1) to (b-6), and _B2 represents a structure selected from the group consisting of the following formulae (b-1) to (b-5). _L1 represents a structure of the following formulae (1L-1) or (1L-2). _L2 represents a single bond, the following formula (2L-1), or a divalent group selected from the group consisting _{of -CH2-} , -CH( _CH3 )-, -C( _CH3 ) _2- , -( _CH2 ) _n- (n represents an integer of 2 to 20) and -NR- (R represents a hydrogen atom or a methyl group) (hereinafter referred to as a linking group (2a)). _{Any CH2} in the above-mentioned -( _CH2 ) _n- may be substituted by -O-, -CH( _CH3 )-, -C( _CH3 ) _2- , -CO- or -NR-. AL ₁ and AL ₂ each independently represent *-Cy ₁ -Z ₁ or *-Cy ₂ . m1 represents an integer of 1 to 4. m2 represents an integer of 1 to 2. _{Cy 1} represents a structure in which two or more rings are linked directly or via a linking group. Cy ₂ represents a group having a steroid skeleton. Z ₁ represents a linear or branched hydrocarbon group having 3 or more carbon atoms.

(However, *1 represents a bonding partner with _AL1 , and *2 represents a bonding partner with _B1 . n1 represents an integer of 1 to 2, and n2 represents an integer of 1 to 4. _A11 and _A12 each independently represent a single bond, -O-, or a linking group (2a). When _A12 exists in plural numbers, the plural _A12s may be the same or different. _A21 and _A22 each independently represent a linking group (2a) (except -NR-). _As11 represents a single bond, -O-, -CO-, or a linking group (2a). _As12 represents a single bond, -CO-, or a linking group (2a) (except -NR-)).

(However, *1 indicates a bond with B ₂ , and *2 indicates a bond with AL _{2. As2} has the same meaning as _As11 above).

(However, * represents a bonding pair, and R ₂ , R _4a , R _4b , R ₅ , and R ₆ each independently represent a hydrogen atom or an alkyl group having 1 to 20 carbon atoms).

The linear or branched alkyl group mentioned _above may be a group in which one or more non-adjacent methylene groups are replaced by oxygen atoms, CO or CO(=O) containing oxygen atoms, or sulfur atoms, or a group in which the hydrogen atom in the methylene group is replaced by an alkoxy group or a halogen group. From the viewpoint of good reproducibility, Z ₁ may include a linear or branched alkyl group having 3 to 20 carbon atoms, a linear or branched fluoroalkyl group having 3 to 20 carbon atoms, a linear or branched alkoxy group having 3 to 20 carbon atoms, or a linear or branched alkyl ester group having 3 to 20 carbon atoms.

For the above Cy ₁ , the rings of the structure in which two or more rings are directly or linked via a linking group are preferably benzene rings, naphthalene rings or cyclohexane rings. When the number of rings constituting a polycyclic structure is two or more, 2 to 4 are preferably present. Furthermore, the plurality of rings constituting the polycyclic structure may be the same or different from each other. When the ring is a benzene ring, the bonding position of the ring is preferably para to other groups. When the ring is a naphthalene ring, the bonding position of the ring is preferably amphi-position (2,6-position) to other groups. When the ring is a cyclohexane ring, the bonding position of the ring is preferably 1,4-position to other groups. In addition, any hydrogen atom on the above ring may be substituted with a halogen atom, a hydroxyl group, a carboxyl group, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkynyl group having 2 to 6 carbon atoms, a monovalent organic group having 1 to 6 carbon atoms containing a fluorine atom, an alkoxy group having 1 to 6 carbon atoms, or the like. Examples of the linking group for the above Cy ₁ include -O-, -CO-, -COO-, -NR ^b -, -CONR ^b - (R ^b is a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or a protecting group), an alkanediyl group having 1 to 10 carbon atoms, or a divalent group in which at least one methylene group of an alkanediyl group having 1 to 10 carbon atoms is substituted with -O-, -CO-, -COO-, -NR ^b -, or -CONR ^b -. Examples of the protecting group for R ^b include a carbamate protecting group. Specific examples of the carbamate protecting group include tert-butyloxycarbonyl and 9-fluorenylmethoxycarbonyl. The above Cy1 is preferably a structure represented by the following formula (Rn). In formula (Rn), X each independently represents a single bond or a divalent group as exemplified by Cy _1. m is 2 to 6. G each independently represents a benzene ring, a naphthalene ring or a cyclohexane ring. * represents a bond.

For the above Cy ₂ , the group having a steroid skeleton is preferably one having 17 to 51 carbon atoms, such as cholesterol, cholesteryl, and ranostanil. From the viewpoint of having a high voltage holding ratio, B ₁ is preferably the above formula (b-1), (b-3), (b-5), or (b-6).

In the present invention, the component (B) may be a compound having a molecular weight of 2000 or less for the purpose of improving reproducibility. Also for the purpose of improving reproducibility, the molecular weight is preferably 1800 or less, and more preferably 1500 or less. The molecular weight of the compound of the component (B) is preferably 100 or more, and more preferably 150 or more for the purpose of improving voltage retention. As the component (B), the compound represented by the above formula (3-1) is preferred for the purpose of having a high voltage retention.

As component (B), it has a high voltage retention rate. From the perspective of easy synthesis, the compound represented by any of the following formulas (B1-1-1) to (B1-1-43), (B1-2-1) to (B1-2-22), (B2-1-1) to (B2-1-18), (B2-2-1) to (B2-2-34), and (B2-3-1) to (B2-3-14) is preferred. From the viewpoint of having a high voltage holding rate, compounds (B1-1-1) to (B1-1-43), (B1-2-1) to (B1-2-22) are preferred. From the viewpoint of easy synthesis, compounds (B1-1-1), (B1-1-3), (B1-1-4), (B1-1-6), (B1-1-8), (B1-1-9), (B1-1-11), (B1-1-12), (B1-1-14), (B1-1-15), (B1-1-17), (B1-1-18), (B1-1-20), (B1-1-21), (B1-1-23), (B1-1-24) or (B1-1-26) are more preferred.

The content of the component (B) is preferably 0.1 to 40 parts by mass, more preferably 0.5 to 35 parts by mass, and particularly preferably 0.5 to 30 parts by mass, based on 100 parts by mass of the component (A).

<Liquid crystal alignment agent> The liquid crystal alignment agent of the present invention contains the above-mentioned (A) component and (B) component. In the liquid crystal alignment agent of the present invention, in addition to the polymers (A-1) to (A-4) containing the above-mentioned (A) component, other polymers may also be contained. As the types of other polymers, polyester, polyamide, polyurea, polyacetal, polystyrene or its derivatives, poly(styrene-phenylmaleimide) derivatives, poly(meth)acrylates, etc. can be cited.

The liquid crystal alignment agent is used for manufacturing the liquid crystal alignment film. From the perspective of forming a uniform thin film, the form of the coating liquid is selected. For the liquid crystal alignment agent of the present invention, a coating liquid containing the above-mentioned (A) component and (B) component and an organic solvent is also preferred. At this time, the content (concentration) of the polymer containing the above-mentioned (A) component in the liquid crystal alignment agent can be appropriately changed by setting the thickness of the coating to be formed. From the perspective of forming a uniform and defect-free coating, 1% by mass or more is preferred, and from the perspective of the storage stability of the solution, 10% by mass or less is preferred, and 2 to 8% by mass is particularly preferred.

The organic solvent contained in the liquid crystal alignment agent is not particularly limited as long as it can uniformly dissolve the polymer component. Specific examples thereof include N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, dimethylsulfoxide, γ-butyrolactone, γ-valerolactone, 1,3-dimethyl-2-imidazolidinone, methyl ethyl ketone, cyclohexanone, cyclopentanone, N,N-dimethyllactamide, 3-methoxy-N,N-dimethylpropaneamide, and 3-butoxy-N,N-dimethylpropaneamide (collectively referred to as good solvents). From the viewpoint of good printability, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, 3-methoxy-N,N-dimethylpropaneamide, 3-butoxy-N,N-dimethylpropaneamide, N,N-dimethyllactamide or γ-butyrolactone is preferred. From the viewpoint of good printability, the good solvent is preferably contained in 20-99% by mass of the total solvent of the liquid crystal alignment agent, more preferably 20-90% by mass, and particularly preferably 30-80% by mass.

In addition, the organic solvent contained in the liquid crystal alignment agent is preferably mixed with a solvent (also called a weak solvent) that improves the coating property or the surface smoothness of the coating film when the liquid crystal alignment agent is applied, in addition to the above-mentioned solvents. Specific examples of weak solvents are given below, but they are not limited to these examples. For example, diisopropyl ether, diisobutyl ether, diisobutyl carbinol (2,6-dimethyl-4-heptanol), ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, 1,2-butoxyethane, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, 4-hydroxy-4-methyl-2-pentanone, diethylene glycol methyl ethyl ether, diethylene glycol dibutyl ether, 3-ethoxybutyl acetate, 1-methylpentyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, ethylene glycol monoacetate, ethylene glycol diacetate, propylene carbonate, ethyl carbonate, ethylene glycol monobutyl ether, ethylene glycol monoisopentyl ether, ethylene glycol monohexyl ether, propylene glycol monobutyl ether, 1-(2-butoxyethoxy)-2- Propanol, 2-(2-butoxyethoxy)-1-propanol, propylene glycol monomethyl ether acetate, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol dimethyl ether, ethylene glycol monobutyl ether acetate, ethylene glycol monoacetate, ethylene glycol diacetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, 2-(2-ethoxyethoxy)ethyl acetate, diethylene glycol acetate, propylene glycol diacetate, n-butyl acetate, propylene glycol monoethyl acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, ethyl 3-methoxypropionate, propyl 3-methoxypropionate, butyl 3-methoxypropionate, n-butyl lactate, isoamyl lactate, diethylene glycol monoethyl ether, diisobutyl ketone (2,6-dimethyl-4-heptanone), etc.

Among the weak solvents, diisobutyl carbinol, propylene glycol monobutyl ether, propylene glycol diacetate, diethylene glycol diethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol dimethyl ether, 4-hydroxy-4-methyl-2-pentanone, ethylene glycol monobutyl ether, ethylene glycol monobutyl ether acetate or diisobutyl ketone are preferred from the viewpoint of good printability. The weak solvent is preferably contained in 1 to 80% by mass of the total solvent of the liquid crystal alignment agent, more preferably 10 to 80% by mass, and particularly preferably 20 to 70% by mass. The type and content of the solvent can be appropriately selected in accordance with the coating device, coating conditions, coating environment, etc. of the liquid crystal alignment agent.

As a combination of a good solvent and a weak solvent, from the viewpoint of good printability, there are N-methyl-2-pyrrolidone and ethylene glycol monobutyl ether, N-methyl-2-pyrrolidone and γ-butyrolactone and ethylene glycol monobutyl ether, N-methyl-2-pyrrolidone and γ-butyrolactone and propylene glycol monobutyl ether, N-ethyl-2-pyrrolidone and propylene glycol monobutyl ether, N-methyl-2-pyrrolidone and γ-butyrolactone and 4-hydroxy-4-methyl-2-pentanone and diethylene glycol diethyl ether, N-methyl-2-pyrrolidone and γ-butyrolactone and propylene glycol monobutyl ether. Lactone and propylene glycol monobutyl ether and diisobutyl ketone, N-methyl-2-pyrrolidone and γ-butyrolactone and propylene glycol monobutyl ether and diisopropyl ether, N-methyl-2-pyrrolidone and γ-butyrolactone and propylene glycol monobutyl ether and diisobutyl carbinol (Carbinol), N-methyl-2-pyrrolidone and γ-butyrolactone and dipropylene glycol dimethyl ether, N-methyl-2-pyrrolidone and propylene glycol monobutyl ether and dipropylene glycol dimethyl ether, N-ethyl-2-pyrrolidone and propylene glycol monobutyl ether and dipropylene glycol dimethyl ether, etc.

The liquid crystal alignment agent of the present invention may contain additional components in addition to the components (A), (B) and the organic solvent. Examples of additional components include adhesion promoters for improving the adhesion between the liquid crystal alignment film and the substrate, the adhesion between the liquid crystal alignment film and the sealant, compounds for improving the strength of the liquid crystal alignment film (hereinafter also referred to as cross-linking compounds), and dielectrics or conductive substances for adjusting the dielectric constant or resistance of the liquid crystal alignment film.

As the crosslinking compound, a compound selected from N,N,N',N'-tetraglycidyl-m-xylenediamine, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenylmethane, N,N,N',N'-tetraglycidyl-p-phenylenediamine, compounds having an oxirane group such as the following formulas (r-1) to (r-3), compounds having a protected isocyanate group such as the following formulas (bi-1) to (bi-3), compounds described in JP-A-2016-200798, hydroxyalkylamide compounds represented by the following formulas (hd-1) to (hd-8), or compounds represented by the following formulas (e-1) to (e-8).

The above compound is an example of a cross-linking compound, but is not limited thereto. For example, there can be cited compounds having an oxacyclobutane group described in [0170] to [0175] of WO2011/132751, compounds containing an oxazoline structure described in [0115] of Japanese Patent Publication No. 2007-286597, compounds having a maltosonic acid structure described in WO2012/091088, compounds having a cyclic carbonate group described in WO2011/155577, and components other than the above disclosed in [0105] to [0116] of WO2015/060357, etc. Two or more types of cross-linking compounds may be used in combination. In the liquid crystal alignment agent of the present invention, the content of the crosslinking compound is preferably 0.5 to 20 parts by mass, more preferably 1 to 15 parts by mass, based on 100 parts by mass of the polymer component contained in the liquid crystal alignment agent, from the viewpoint of achieving the intended effect and improving the liquid crystal alignment.

Examples of the adhesion promoter include 3-aminopropyl trimethoxysilane, 3-aminopropyl triethoxysilane, 3-aminopropyl diethoxymethyl silane, 2-aminopropyl trimethoxysilane, 2-aminopropyl triethoxysilane, N-(2-aminoethyl)-3-aminopropyl trimethoxysilane, N-(2-aminoethyl)-3-aminopropyl methyl dimethoxysilane, 3-ureapropyl trimethoxysilane, Silane, 3-ureidopropyl triethoxysilane, N-ethoxycarbonyl-3-aminopropyl trimethoxysilane, N-ethoxycarbonyl-3-aminopropyl triethoxysilane, N-triethoxysilylpropyl triethylene triamine, N-trimethoxysilylpropyl triethylene triamine, N-bis(oxyethylene)-3-aminopropyl trimethoxysilane, N-bis(oxyethylene)-3-aminopropyl triethoxysilane, Alkenyl trimethoxysilane, vinyl triethoxysilane, 2-(3,4-epoxycyclohexyl)ethyl trimethoxysilane, 3-glycidoxypropyl methyl dimethoxysilane, 3-glycidoxypropyl trimethoxysilane, 3-glycidoxypropyl methyl diethoxysilane, 3-glycidoxypropyl triethoxysilane, p-styrene trimethoxysilane, 3-methacryloyloxypropyl methyl dimethoxysilane Silane coupling agents such as 3-methacryloxypropyl trimethoxysilane, 3-methacryloxypropyl methyldiethoxysilane, 3-methacryloxypropyl triethoxysilane, 3-acryloxypropyl trimethoxysilane, tris(3-trimethoxysilylpropyl) isocyanurate, 3-butylenepropyl methyldimethoxysilane, 3-butylenepropyl trimethoxysilane, and 3-isocyanatepropyl triethoxysilane are used. From the viewpoint of improving the liquid crystal alignment, the amount of the silane coupling agent used is preferably 0.1 to 30 parts by mass, and more preferably 0.1 to 20 parts by mass, based on 100 parts by mass of the polymer component contained in the liquid crystal alignment agent.

<Liquid crystal alignment film and liquid crystal display element> The liquid crystal display element of the present invention is a liquid crystal alignment film formed by using the above-mentioned liquid crystal alignment agent. The operation mode of the liquid crystal display element is not particularly limited, and it is applicable to various operation modes such as TN type, STN type, vertical alignment type (including VA-MVA type, VA-PVA type, etc.), in-plane switching type (IPS type), FFS type, optical compensation bending type (OCB type), etc.

The liquid crystal display element of the present invention is manufactured, for example, by the following steps (1-1) to (1-3). Step (1-1) uses different substrates depending on the desired operation mode. Step (1-2) and step (1-3) are common in each operation mode.

[Step (1-1): Formation of coating film] First, the liquid crystal alignment agent of the present invention is applied on a substrate, and then a coating film is formed on the substrate by heating the coated surface. (1-1A) For example, when manufacturing a TN type, STN type or VA type liquid crystal display element, first, two substrates provided with a patterned transparent conductive film are used as a pair, and the liquid crystal alignment agent is preferably applied on each transparent conductive film forming surface by offset printing, rotary coating, roll coating or inkjet printing. As the substrate, for example, a transparent substrate made of glass such as float glass and soda glass; and plastics such as polyethylene terephthalate, polybutylene terephthalate, polyether sulfone, polycarbonate, and poly(aliphatic cycloolefin) can be used. As the transparent conductive film provided on one side of the substrate, a NESA film (trademark of PPG) made of tin oxide (SnO ₂ ), an ITO film made of indium oxide-tin oxide (In ₂ O ₃ -SnO ₂ ), or the like can be used.

After applying the liquid crystal alignment agent, it is preferred to perform preliminary heating (pre-baking) in order to prevent the liquid of the applied liquid crystal alignment agent from drooping. The pre-baking temperature is preferably 30 to 200°C, preferably 40 to 150°C, and particularly preferably 40 to 100°C. Thereafter, the solvent is completely removed, and a baking (post-baking) step is performed as necessary for the purpose of thermally imidizing the amide structure present in the polymer. The baking temperature (post-baking temperature) at this time is preferably 80 to 300°C, preferably 120 to 250°C. The post-baking time is preferably 5 to 200 minutes, preferably 10 to 100 minutes. The thickness of the film formed in this way is preferably 0.001 to 1μm, preferably 0.005 to 0.5μm.

(1-1B) When manufacturing IPS or FFS type liquid crystal display elements, a crystal orientation agent is applied to the electrode forming surface of a substrate provided with an electrode formed by a comb-shaped transparent conductive film or a metal film, and to the side of an opposite substrate without an electrode, and then a coating film is formed by heating each coated surface. The materials of the substrate and transparent conductive film used at this time, the coating method, the heating conditions after coating, the method of patterning the transparent conductive film or the metal film, the substrate pre-treatment, and the preferred film thickness of the formed coating film are the same as those in (1-1A) above. As the metal film, for example, a film formed by a metal such as chromium can be used.

In either of the above (1-1A) and (1-1B), after coating the liquid crystal alignment agent on the substrate, the organic solvent is removed to form a coating film that becomes a liquid crystal alignment film. At this time, by further heating the coating film after formation, the dehydration and ring-closing reaction of the polyamine acid, polyamine ester and polyimide added to the liquid crystal alignment agent proceeds, and the coating film can also be further imidized.

[Step (1-2): Treatment for imparting alignment energy] In manufacturing TN type, STN type, IPS type or FFS type liquid crystal display elements, the coating formed in the above step (1-1) is subjected to treatment for imparting liquid crystal alignment energy. Examples of treatment for imparting alignment energy include rubbing treatment in which a cloth made of fibers such as nylon, rayon, and cotton is rolled up and rubbed in a certain direction, and light alignment treatment in which polarized or non-polarized radiation is irradiated on the coating. On the other hand, in the case of VA type liquid crystal display elements, the coating formed in the above step (1-1) can be used directly as a liquid crystal alignment film, but the coating can also be subjected to treatment for imparting alignment energy.

When imparting liquid crystal alignment ability to a coating treated with photo-alignment, ultraviolet light or visible light having a wavelength of 150 to 800 nm may be used as radiation irradiating the coating. When the radiation is polarized, it may be linearly polarized or partially polarized. Furthermore, when the radiation used is linearly polarized or partially polarized, the irradiation may be performed in a direction perpendicular to the substrate surface, in an oblique direction, or in combination thereof. When irradiating with non-polarized radiation, the irradiation direction is set to an oblique direction.

As the light source, for example, a low-pressure mercury lamp or a high-pressure mercury lamp can be used. The ultraviolet light in the preferred wavelength region can be obtained by using a light source such as a filter or a diffraction grating. The radiation dose is preferably 10 to 5,000 mJ/cm ² , more preferably 30 to 2,000 mJ/cm ² .

Furthermore, the light irradiation of the coating may be performed while heating the coating to enhance the reactivity. The heating temperature is usually 30 to 250°C, preferably 40 to 200°C, and more preferably 50 to 150°C.

Furthermore, when ultraviolet light containing a wavelength of 150 to 800 nm is used, the light irradiated film obtained in the above step can be used directly as a liquid crystal alignment film, but the light irradiated film can also be baked, washed with water or an organic solvent, or a combination thereof. The baking temperature at this time is preferably 80 to 300°C, preferably 80 to 250°C. The baking time is preferably 5 to 200 minutes, preferably 10 to 100 minutes. Moreover, the baking can be performed more than twice. The light alignment treatment here is equivalent to the light irradiation treatment in a state where it is not in contact with the liquid crystal layer.

As described above, a liquid crystal alignment film is formed on a substrate by a liquid crystal alignment agent. However, if defects occur in the liquid crystal alignment film, the liquid crystal alignment film formed by the liquid crystal alignment agent of the present invention is excellent in the reprocessing step of removing such defects from the substrate and regenerating the substrate. That is, the optimal temperature for the reprocessing step is 20 to 100°C when the substrate with the liquid crystal alignment film is immersed in a solvent, and then removed by pure water. However, the liquid crystal alignment film formed by the liquid crystal alignment agent of the present invention has the following advantages in the reprocessing step. That is, the liquid crystal alignment film formed by the liquid crystal alignment agent of the present invention has high solubility in the reprocessing agent, so it has the advantages of increasing the types of solvents that can be used, or reducing the temperature or immersion time in the solvent, thereby reducing the manufacturing cost.

[Step (1-3): Construction of liquid crystal unit] (1-3A) As described above, two substrates with liquid crystal alignment films are prepared, and a liquid crystal unit is manufactured by arranging liquid crystal between the two substrates arranged opposite to each other. Specifically, the following two methods can be cited. The first method is to first arrange the liquid crystal alignment films opposite to each other with a gap (cell gap) between them, and arrange the two substrates opposite to each other, and then adhere the peripheral parts of the two substrates with a sealant. After the liquid crystal is injected and filled in the divided cell gap through the substrate surface and the sealant, the liquid crystal unit is manufactured by sealing the injection hole. The second method is also called the ODF (One Drop Fill) method. For example, a UV-curable sealant is applied to a predetermined location on one of the two substrates on which a liquid crystal alignment film is formed, and then liquid crystal is dripped at a predetermined location on the surface of the liquid crystal alignment film, and then the other substrate is bonded so that the liquid crystal alignment films are opposite, and at the same time, the liquid crystal is squeezed and expanded on the entire substrate, and then ultraviolet light is irradiated on the entire substrate to cure the sealant and produce a liquid crystal unit. In the case obtained by any method, it is preferred that the liquid crystal unit produced is further heated to a temperature at which the used liquid crystal becomes an isotropic phase, and then gradually cooled to room temperature to remove the flow alignment when the liquid crystal is filled. As a sealant, for example, an epoxy resin containing a hardener and aluminum oxide balls as spacers can be used.

As liquid crystal, nematic liquid crystal, smectic liquid crystal, etc. can be cited, among which nematic liquid crystal is also preferred, for example, Schiff base series, oxyazo series, biphenyl series, phenylcyclohexane series, ester series, terphenyl series, biphenylcyclohexane series, pyrimidine series, dioxane series, bicyclooctane series, square alkane series, etc. In addition, cholesteric liquid crystals such as cholesteryl chloride, cholesteryl nonanoate, and cholesteryl carbonate can also be added to these liquid crystals; chiral agents such as "C-15" and "CB-15" (trade names of Merck); strong dielectric liquid crystals such as p-decyloxybenzylene-p-amino-2-methylbutylcinnamate, etc.

In addition, the liquid crystal may contain anisotropic dyes. For example, black dyes or color dyes may be used. The proportion of the anisotropic dye in the liquid crystal may be appropriately selected within a range that does not damage the desired physical properties, for example, 0.01 to 5 parts by mass relative to 100 parts by mass of the liquid crystal compound, but may be appropriately changed as necessary.

(1-3B) In the case of a PSA type liquid crystal display element, a liquid crystal cell is constructed in the same manner as in (1-3A) above except that a photopolymerizable compound such as the following formula (w-1) to (w-5) is injected or dripped simultaneously with the liquid crystal.

The liquid crystal unit is irradiated with light while a voltage is applied between the conductive films of a pair of substrates. The voltage applied here may be, for example, a direct current or alternating current of 5 to 50 V. As the irradiated light, for example, ultraviolet light or visible light having a wavelength of 150 to 800 nm may be used, but ultraviolet light having a wavelength of 300 to 400 nm is preferred. The irradiation amount of light is preferably 100 to 30,000 mJ/cm ² , more preferably 100 to 20,000 mJ/cm ² .

(1-3C) When a liquid crystal alignment agent containing a compound having a photopolymerizable group is used to form a coating on a substrate, a liquid crystal unit is constructed in the same manner as in (1-3A) above, and then a method for manufacturing a liquid crystal display element can be adopted by irradiating the liquid crystal unit with light while a voltage is applied between conductive films on a pair of substrates. As additives having a photopolymerizable group, the structures exemplified in the above formulas (w-1) to (w-5) can be cited. The amount thereof is preferably 1 to 30% by mass, more preferably 1 to 20% by mass, and particularly preferably 1 to 15% by mass relative to the solid components contained in the liquid crystal alignment agent.

The light irradiation of the liquid crystal unit can be performed in a state where the liquid crystal is driven by applying a voltage, or can be performed in a state where a low voltage is applied to a degree that the liquid crystal is not driven. The applied voltage can be, for example, a direct current or alternating current of 0.1 to 30 V. The conditions of the irradiated light can be applied as described in (1-3B) above. The light irradiation treatment here is equivalent to the light irradiation treatment in a state of contact with the liquid crystal layer.

Then, by attaching a polarizing plate to the outer surface of the liquid crystal unit, the liquid crystal display element of the present invention can be obtained. As the polarizing plate attached to the outer surface of the liquid crystal unit, there can be cited a polarizing plate in which a polarizing film called "H film" that stretches polyvinyl alcohol to absorb iodine is sandwiched by a cellulose acetate protective film or a polarizing plate formed by the H film itself. [Example]

The following examples are given to illustrate the present invention in more detail, but the present invention is not limited thereto. The abbreviations of the compounds and the methods for measuring the properties are shown below. Compound (c-1) is synthesized according to the method described in Synthesis Example 3 of Japanese Patent Publication No. 2008-052260. (Diamine) DA-1 to DA-27: Each is a compound represented by the following formula (DA-1) to (DA-27) (Tetracarboxylic dianhydride) CA-1 to CA-8: Each is a compound represented by the following formula (CA-1) to (CA-8) (Tetracarboxylic diester dihalide) CE-1: Compound represented by the following formula (CE-1)

(Monocarboxylic acid chloride) E-1: Acryloyl chloride (Component B) b-1 to b-8: Compounds represented by the following formulas (b-1) to (b-8) (Other additives) c-1 to c-4: Compounds represented by the following formulas (c-1) to (c-4) F-1: N-α-(9-fluorenylmethyloxycarbonyl)-N-τ-t-butoxycarbonyl-L-histidine (compound of formula (F-1)) s-1: 3-glycidoxypropyltriethoxysilane (compound of formula (s-1)) s-2: 3-glycidoxypropylmethyldiethoxysilane (compound of formula (s-2)) M-1: 3-picolylamine

(Organic solvents) NMP: N-methyl-2-pyrrolidone, GBL: γ-butyrolactone, BCS: butyl solvent, DIBK: diisobutyl ketone, NEP: N-ethyl-2-pyrrolidone, DAA: diacetone alcohol, PC: propylene carbonate, DME: dipropylene glycol dimethyl ether, DPM: dipropylene glycol monomethyl ether, PB: propylene glycol monobutyl ether, PGDAC: propylene glycol diacetate, DEDE: diethylene glycol diethyl ether, GVL: γ-valerolactone, DML: N,N-dimethyl lactamide, EEP: 3-ethoxyethyl propionate

(Fmoc represents a 9-fluorenylmethyloxycarbonyl group. In the formula (c-4), R represents a hydroxymethyl group or a -CH ₂ -OC ₈ H ₁₇ group).

[Viscosity] Measured using an E-type viscometer TVE-22H (manufactured by Toki Sangyo Co., Ltd.) with a sample volume of 1.1 mL and a conical rotor TE-1 (1°34', R24) at a temperature of 25°C. [Molecular weight] Measured using a room temperature GPC (gel permeation chromatography) apparatus, and Mn and Mw were calculated as polyethylene glycol and polyethylene oxide conversion values. GPC apparatus: Shodex (GPC-101), column: Shodex (GPC KD-803, GPC KD-805 in-line), column temperature: 50°C, solvent: N,N-dimethylformamide (as additive, lithium bromide monohydrate (LiBr･H ₂ O) is 30 mmol/L, phosphoric acid･anhydrous crystals (o-phosphoric acid) is 30 mmol/L, tetrahydrofuran (THF) is 10 mL/L), flow rate: 1.0 mL/min. Standard sample for standard curve preparation: Tosoh TSK standard polyethylene oxide (Mw: about 900,000, 150,000, 100,000, 30,000), and Polymer Polyethylene glycol manufactured by Labolry (Absorption peak molecular weight (Mp) of about 12,000, 4,000, and 1,000). In order to avoid overlapping absorption peaks, the measurement was performed on two samples of a mixture of four samples of 900,000, 100,000, 12,000, and 1,000, and a mixture of three samples of 150,000, 30,000, and 4,000.

<Imidization rate> Put 20 mg of polyimide powder in an NMR sample tube (NMR sample tube standard, φ5 (manufactured by Kusano Scientific Co., Ltd.)), add dimethyl sulfoxide deuteride (DMSO-d6, 0.05% TMS (tetramethylsilane) mixture) (0.53 ml), and apply ultrasound to completely dissolve it. The solution is measured by 500 MHz proton NMR using an NMR measuring instrument (JNW-ECA500) (manufactured by JEC Data Corporation). The imidization rate is determined by using the proton from a structure that does not change before and after imidization as a reference proton, and the absorption peak integral value of the proton from the NH group of the amide appearing around 9.5 ppm to 10.0 ppm is used to obtain the following formula. Imidization rate (%) = (1-α･x/y) × 100 In the above formula, x is the proton absorption peak integral value from the NH group of acylamidin, y is the absorption peak integral value of the reference proton, and α is the ratio of the number of reference protons to the N1H protons of acylamidin in polyacylamidin (acymidization rate 0%).

[Synthesis of component (B)] <Synthesis Example (b-1)> Compound (b-1) was synthesized according to the route shown below.

In a tomato-shaped flask, add a few drops of compound (b-1-1) (5.00 g; 16.5 mmol), toluene (19.64 g), sulfinyl chloride (5.90 g; 49.5 mmol) and N,N-dimethylformamide (DMF) using Pasteur, stir at room temperature, raise the temperature to 70°C, and react for 6 hours under a nitrogen atmosphere. The reaction solution is concentrated under reduced pressure to obtain compound (b-1-2). In another tomato-shaped flask, add diethanolamine (3.47 g; 33.0 mmol), triethylamine (2.51 g; 24.8 mmol) and 30 mL of dichloromethane, and stir under ice-cooling conditions. Next, add a solution of 8 mL of dichloromethane in which the compound (b-1-1) obtained above is dissolved, and stir overnight. After the reaction is completed, add saturated saline to the reaction solution, take out the organic layer, and further wash the organic layer with saturated saline. Dry the obtained organic layer with sodium sulfate, and concentrate the obtained solution under reduced pressure. Wash the precipitated solid with heptane to obtain 5.29 g of compound (b-1).

<Synthesis Example (b-2)> Compound (b-2) was synthesized according to the following route.

In an eggplant-shaped flask, add 5-aminoisophthalic acid (11.97 g; 66.1 mmol) and N,N-dimethylacetamide (DMAc) (111.97 g) and stir. Next, drop a solution of compound (b-1-2) (21.21 g; 66.1 mmol) dissolved in toluene (28.00 g) into the eggplant-shaped flask and heat to 60°C. After reacting overnight under a nitrogen environment, the reaction solution was injected into a mixed solution of ethanol (80 mL) and water (400 mL) to precipitate a solid. The solid was recovered and dried to obtain 31.07 g of compound (b-2-1). Compound (b-2-1) (5.00 g; 10.7 mmol), diethanolamine (2.37 g; 22.5 mmol), THF (27.27 g), and 4-(4,6-dimethoxy-1,3,5-triazine-2-yl)-4-methylmorpholinium chloride (DMT-MM) (6.23 g; 22.5 mmol) were then added to the eggplant-shaped flask and reacted at room temperature for 5 hours. Saturated brine was added to the reaction solution and the organic layer was taken out. The organic layer was dried with sodium sulfate, and acetonitrile was added to the obtained solution to precipitate a solid. The obtained solid was recovered and dried to obtain 3.57 g of compound (b-2).

<Synthesis Example (b-3)> Compound (b-3) was obtained by following the same procedure as in Synthesis Example (b-2) except that ethanolamine was used in place of diethanolamine.

<Synthesis Example (b-4)> Compound (b-4) was synthesized according to the following route. Compound (b-4-4) was synthesized in the same manner as in Example 3 of JP-A-2010-285367.

Compound (b-4-1) (5.00 g; 21.4 mmol) and THF (70 g) were added to an eggplant-shaped flask to dissolve compound (b-4-1). Diethanolamine (4.72 g; 44.9 mmol) and 4-(4,6-dimethoxy-1,3,5-triazine-2-yl)-4-methylmorpholinium chloride (DMT-MM) (6.23 g; 22.5 mmol) were then added and stirred at room temperature. Saturated saline solution was added to the obtained solution, and the organic layer was taken out. The organic layer was dried with sodium sulfate, and the obtained solution was concentrated under reduced pressure to obtain 5.90 g of compound (b-4-2).

Next, compound (b-4-2) (5.00 g; 12.3 mmol) and 160 mL of 4N hydrochloric acid/ethyl acetate were added to an eggplant-shaped flask, and the mixture was stirred at room temperature for 4 hours. Next, the solvent was distilled off from the stirred solution under reduced pressure to obtain 3.50 g of compound (b-4-3). Next, compound (b-4-3) (3.00 g; 9.76 mmol), compound (b-4-4) (4.77 g; 9.76 mmol), 4-(4,6-dimethoxy-1,3,5-triazine-2-yl)-4-methylmorpholinium chloride (DMT-MM) (2.77 g; 10.0 mmol) and THF (50 g) were added to the eggplant-shaped flask, and the mixture was reacted at room temperature for 5 hours. Saturated saline was added to the reaction solution, and the organic layer was taken out. The organic layer was dried with sodium sulfate, and the obtained solution was concentrated under reduced pressure to obtain 5.00 g of compound (b-4).

<Synthesis Example (b-5)> Compound (b-5) was obtained by the same procedure as in Synthesis Example (b-4) except that diethanolamine was used instead of Compound (b-4-3).

<Synthesis Example (b-6)> Compound (b-6) was obtained by the same procedure as Synthesis Example (b-4), except that trishydroxymethylaminomethane was used as the substitution compound (b-4-3) and trans,trans-4'-pentylcyclohexyl-4-carboxylic acid was used as the substitution compound (b-4-4).

<Synthesis Example (b-7)> Compound (b-7) was synthesized according to the following route. Compound (b-7-1) was synthesized by the same procedure as Synthesis Example 4 of WO2018/159733. Compound (b-7-2) was synthesized by the same procedure as Synthesis Example (b-2) except that compound (b-7-1) was used to replace compound (b-1-2). Next, compound (b-7) was synthesized by the same procedure as Synthesis Example (b-2) except that (b-7-2) was used to replace compound (b-2-1) and tris(hydroxymethyl)aminomethane was used to replace diethanolamine.

<Synthesis Example (b-8)> Compound (b-8) was obtained by the same procedure as in Synthesis Example (b-4) except that trishydroxymethylaminomethane was used in place of compound (b-4-3).

<Synthesis Example (c-3)> Compound (c-3) was obtained by the same procedure as Synthesis Example (b-4) except that monoethanolamine was used instead of Compound (b-4-3).

<Synthesis Example (c-4)> Compound (c-4) was synthesized by the same procedure as Example 4 of Japanese Patent Application Laid-Open No. 2011-70161. [Synthesis of Polymer (A)] <Synthesis Example 1> CA-2 (2.25 g; 8.99 mmol), DA-6 (2.97 g; 8.99 mmol), DA-7 (3.43 g; 9.01 mmol), and NMP (34.6 g) were added to a four-necked flask equipped with a stirring device and a nitrogen inlet tube, dissolved, and reacted at 60°C for 4 hours. Thereafter, CA-3 (1.75 g; 8.92 mmol) and NMP (6.99 g) were added, and reacted at 40°C for 4 hours to obtain a polyamine solution. After adding NMP to the polyimide solution (40g) and diluting it to 6.5% by mass, acetic anhydride (7.06g) and pyridine (2.19g) were added as imidization catalysts and reacted at 80°C for 4 hours. The reaction solution was put into methanol (463g) and the resulting precipitate was separated by filtration. The precipitate was washed with methanol and dried under reduced pressure at 100°C to obtain polyimide powder (Mn: 12500; Mw: 38500; imidization rate: 74%). NMP (18.0 g) was added to the obtained polyimide powder (2.0 g), and M-1 was added to 1 mass % relative to the solid content of the polyimide. After stirring and dissolving at 70° C. for 12 hours, a solution of polyimide (PI-V-1) with a solid content concentration of 10% was obtained.

<Synthesis Example 2> CA-2 (1.20 g; 4.80 mmol), DA-8 (1.46 g; 9.59 mmol), DA-9 (1.74 g; 7.18 mmol), DA-7 (2.74 g; 7.20 mmol), and NMP (28.58 g) were added to a four-necked flask equipped with a stirring device and a nitrogen inlet tube, dissolved, and reacted at 60°C for 2 hours. Thereafter, CA-5 (1.05 g; 4.81 mmol) and NMP (4.19 g) were added, reacted at room temperature for 4 hours, and CA-3 (2.78 g; 14.18 mmol) and NMP (11.1 g) were further added, and reacted at room temperature for 4 hours to obtain a polyamine solution. After adding NMP to the polyimide solution (40g) and diluting it to 6.5% by mass, acetic anhydride (8.90g) and pyridine (2.76g) were added as imidization catalysts, and the reaction was carried out at 80°C for 4 hours. The reaction solution was put into methanol (472g) and the obtained precipitate was separated by filtration. After the precipitate was washed with methanol, it was dried under reduced pressure at 100°C to obtain polyimide powder (Mn: 13000; Mw: 39000; imidization rate: 74%). NMP was added to the obtained polyimide powder to a solid content concentration of 10% by mass, and M-1 was added to a content of 1% by mass relative to the polyimide solid content. The mixture was stirred at 70° C. for 12 hours to dissolve the mixture, thereby obtaining a polyimide (PI-V-2) solution.

<Synthesis Example 3> In a four-necked flask equipped with a stirring device and a nitrogen inlet tube, add 5.86g (24.0mmol) of DA-2, 5.46g (16.0mmol) of DA-10, 1.73g (16.0mmol) of DA-4, 7.69g (24.0mmol) of DA-1, and 194g of NMP, and stir and dissolve while introducing nitrogen. Add 17.1g (76.4mmol) of CA-1 to the diamine solution while stirring, and further add NMP until the solid content concentration becomes 12% by mass, and stir at 40°C for 24 hours to obtain a polyamide solution (viscosity: 549mPa･s, Mn of polyamide is 12400; Mw is 33000). After adding NMP to the polyimide solution (225g) and diluting to 9.0 mass%, acetic anhydride (17.1g) and pyridine (3.54g) as an imidization catalyst were added and reacted at 55°C for 3 hours. The reaction solution was put into methanol (1111g) and the obtained precipitate was separated by filtration. The precipitate was washed with methanol and dried at 60°C for 12 hours to obtain polyimide powder (Mn: 11000; Mw: 28000; imidization rate: 66%). NMP was added to the obtained polyimide powder to a solid content concentration of 15% by mass, and the mixture was stirred and dissolved at 70° C. for 24 hours to obtain a polyimide (PI-I-3) solution.

<Synthesis Example 4> In a 5L four-necked flask equipped with a stirring device and a nitrogen inlet tube, add 5.73g (20.0mmol) of DA-5 and 115g of NMP, and stir and dissolve while introducing nitrogen. Add 2.94g (15.0mmol) of CA-3 to the diamine solution under water cooling, add 19.1g of NMP, and stir at 23°C for 1 hour in a nitrogen environment. Then, weigh and take out 11.9g (40.0mmol) of DA-3 and 6.01g (40.0mmol) of DA-11, add 72g of NMP, and stir and dissolve while introducing nitrogen. The diamine solution was stirred under water cooling, and 15.9 g (81.0 mmol) of CA-3 was added. NMP was added to a solid content of 15% by mass, and s-1 was added to a content of 1% by mass relative to the polyamide solid content. The mixture was stirred at 23°C for 6 hours under a nitrogen environment to obtain a polyamide (PAA-I-4, Mn: 12000; Mw: 30000) solution.

<Synthesis Example 5> A 500 mL four-necked flask with a stirrer was placed in a nitrogen atmosphere, and 2.80 g (25.9 mmol) of DA-4, 1.58 g (6.47 mmol) of DA-2, 111 g of NMP, and 6.18 g (78.1 mmol) of pyridine as a base were added and stirred to dissolve. Next, 9.89 g (30.4 mmol) of CE-1 was added while stirring the diamine solution, and the mixture was reacted at 15°C overnight. After stirring overnight, 0.38 g (4.21 mmol) of E-1 was added, and the mixture was reacted at 15°C for 4 hours. The obtained polyamic acid ester solution was added to 1230 g of water while stirring, and the precipitated white precipitate was filtered out and washed with 1230 g of isopropyl alcohol (IPA) for 5 times. After drying, 10.2 g (yield: 83.0%) of white polyamic acid ester powder (Mn: 20786; Mw: 40973) was obtained. GBL was added to the obtained polyamic acid ester powder until the solid content concentration became 10% by mass, and stirred and dissolved at room temperature for 24 hours to obtain a polyamic acid ester (PAE-I-5) solution.

<Synthesis Example 6> In a four-necked flask equipped with a stirring device and a nitrogen inlet tube, add 0.46g (3.00mmol) of DA-8, 3.00g (15.0mmol) of DA-13, 2.56g (12.0mmol) of DA-14, 11.0g of NMP, and 8.10g of GBL, and stir to dissolve while introducing nitrogen. While stirring the diamine solution, add 4.76g (24.0mmol) of CA-6, add 10.9g of GBL, and stir at room temperature for 2 hours. Then, add 10.8g of GBL and stir, then add 1.31g (6.01mmol) of CA-5, add 14.3g of GBL, and stir at room temperature for 24 hours. The viscosity of the obtained polyamine (Mn: 14200; Mw: 30110) solution was 2,041 mPa･s. Then, s-2 was added to 1% by mass relative to the solid content of polyamine, the mixing ratio of NMP and GBL became NMP:GBL = 20:80 by mass, and NMP and GBL were added until the solid content concentration became 15% by mass to obtain a polyamine (PAA-I-6) solution.

<Synthesis Examples 7 to 11, 14 to 20> As shown in Table 1 below, diamine, tetracarboxylic acid derivatives and organic solvents were used, and each was carried out by the same procedure as the above-mentioned synthesis examples to obtain solutions of polyimides (PI-V-V-8), (PI-V-9), (PI-I-11), (PI-V-19) and (PI-V-20), polyamides (PAA-I-7), (PAA-I-10), (PAA-V-14) to (PAA-V-16), (PAA-I-17) and (PAA-I-18) shown in Table 1 below. In Table 1, the values in parentheses represent the mixing ratio (molar parts) of each compound in the tetracarboxylic acid component relative to 100 mol parts of the total amount of the tetracarboxylic acid derivatives used in the synthesis. For the diamine acid component, the mixing ratio (mol parts) of each compound relative to 100 mol parts of the total amount of diamines used in the synthesis is shown. For the terminal sealant, the mixing ratio (mol parts) relative to 100 mol parts of the total amount of diamines used in the synthesis is shown. For the organic solvent, the mixing ratio (mass parts) of each organic solvent relative to 100 mass parts of the total amount of organic solvents used in the synthesis is shown.

[Synthesis of other polymers] <Synthesis Example 12> According to the method described in [0091] of Japanese Patent Application Laid-Open No. 2018-54761, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane (ECETS) was used to obtain a reactive polyorganosiloxane polymer. Next, according to the method described in [0093] of Japanese Patent Application Laid-Open No. 2018-54761, a polymer of a polyorganosiloxane represented by the following formula (P-S1) was obtained. In addition, the numerical values (70, 20, 10) in formula (P-S1) represent the usage ratio (molar parts) of each compound relative to the total of each silane compound used in the synthesis. <Synthesis Example 13> According to the method described in [0091] of Japanese Patent Application Laid-Open No. 2018-54761, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane (ECETS) was used to obtain a reactive polyorganosiloxane polymer. Next, according to the method described in [0093] of Japanese Patent Application Laid-Open No. 2018-54761, a polymer of a polyorganosiloxane represented by the following formula (P-S2) was obtained. In addition, the numerical values (70, 30) in formula (P-S2) represent the usage ratio (molar parts) of each compound relative to the total of each silane compound used in the synthesis.

<Example 1> [Preparation of liquid crystal alignment agent] The solution of polyimide (PI-V-1) obtained in Synthesis Example 1 and the solution of polyimide (PI-V-2) obtained in Synthesis Example 2 were diluted with NMP and BCS, and compounds (b-1) and (b-2) were further added to 1 part by mass and 5 parts by mass, respectively, relative to 100 parts by mass of the total polymer, and stirred at room temperature. Next, the obtained solution was filtered through a filter with a pore size of 0.5 μm to obtain a liquid crystal alignment agent (V1) having a polymer component ratio (solid component converted mass ratio) of (PI-V-1):(PI-V-2)=30:70, a solvent composition ratio (mass ratio) of NMP:BCS=60:40, a polymer solid component concentration of 4.5%, a compound (b-1) ratio of 1 mass part, and a compound (b-2) ratio of 5 mass parts (see Table 2-1 below). In the liquid crystal alignment agent, no abnormal turbidity or precipitation was observed, and a uniform solution was confirmed. <Examples 2 to 50, Comparative Examples 1 to 6> Except for using the polymers and additives in Tables 2-1 to 2-4 below, the same method as in Example 1 was used to obtain liquid crystal alignment agents (V2) to (V11), (I12-P) to (I29-P), (I30-U) to (I37-U), (V38) to (V43), (I44-P) to (I47-P), (V48-P) to (V49-P), (I50-U), (R-V1) to (R-V2), (R-I3-P), (R-I4-U), (R-V5) to (R-V6). In Tables 2-1 to 2-4, the values in parentheses indicate, for polymers and additives, the proportion (in parts by mass) of each polymer component or additive relative to 100 parts by mass of the total polymer component used in the preparation of each liquid crystal alignment agent. For organic solvents, it indicates the proportion (in parts by mass) of each organic solvent relative to 100 parts by mass of the total organic solvent used in the preparation of the liquid crystal alignment agent.

[Evaluation of the reproducibility of the liquid crystal alignment agent] The liquid crystal alignment agent obtained above was applied to the ITO substrate by spin coating. After drying on a 60°C heating plate for 1 minute and 30 seconds, it was baked in a 230°C hot air circulation oven for 20 minutes to form a coating with a thickness of 100nm. After that, the prepared substrate was immersed in NMP heated at 35°C or 50°C for 5 minutes, and then washed with ultrapure water for 20 seconds. The samples with no residual coating after immersion in NMP at 35°C for 5 minutes were evaluated as "excellent", the samples with no residual coating after immersion in NMP at 50°C for 5 minutes were evaluated as "good", and the samples with no residual coating after immersion in NMP at 50°C for 5 minutes were evaluated as "poor".

[Production and evaluation of liquid crystal display elements] 1-1. Production of vertical alignment type liquid crystal display elements Prepare 2 glass substrates with ITO electrodes (length: 40mm, width: 30mm, thickness: 1.1mm) and wash them with pure water and isopropyl alcohol. Next, spin-coat each ITO surface with liquid crystal alignment agents (V1) to (V11), (V38) to (V43) and (R-V1) to (R-V2), (R-V5) to (R-V6) filtered by a filter with an aperture of 1.0μm, and heat them on a hot plate at 70℃ for 90 seconds, and heat them in a thermal cycle type sterile oven at 230℃ for 30 minutes to obtain an ITO substrate with a film with a thickness of 100nm. Next, a sealant (XN-1500T manufactured by Mitsui Chemicals Co., Ltd.) is applied around the surface. Next, the side of the liquid crystal alignment film formed on the other substrate is used as the inner side, and after the aforementioned substrate is bonded, the sealant is hardened to produce a hollow cell. Liquid crystal MLC-3023 (trade name manufactured by Merck) is injected into the hollow cells using liquid crystal alignment agents (V1) to (V2), (V5) to (V11), (V38) to (V43), and (R-V1) by a reduced pressure injection method to produce a liquid crystal unit.

Thereafter, a 15V DC voltage was applied to the obtained liquid crystal unit, and when all pixel areas were in the driving state, a UV irradiation device using a high-pressure mercury lamp as a light source was used to irradiate 10J/ ^cm2 of UV light through a bandpass filter with a wavelength of 365nm, thereby obtaining a liquid crystal display element for evaluation. The UV irradiation amount was measured using a photoreceiver connected to UV-M03A manufactured by ORC Corporation with UV-35. Liquid crystal MLC-6608 (trade name manufactured by Merck) was injected into the cells using liquid crystal alignment agents (V3) to (V4) and (R-V2), (R-V5) to (R-V6) by the reduced pressure injection method, thereby obtaining a liquid crystal display element for evaluation. When the obtained liquid crystal display element was observed with a polarizing microscope, it was confirmed that the liquid crystal was uniformly aligned.

1-2. Evaluation of liquid crystal display element [Evaluation of voltage retention rate] The liquid crystal display element produced in 1-1 above was placed in an 80°C oven under LED light for 200 hours, then placed at room temperature and naturally cooled to room temperature. After that, 1V voltage was applied at 60°C with an application time of 60 microseconds and a span of 1667 milliseconds, and the voltage retention rate was measured 1,000 milliseconds after the application was released. As a measuring device, the one made by Toyo TEKNIKA Co., Ltd. was used. The evaluation results are shown in Table 3.

2-1. Fabrication of FFS-type liquid crystal display element by photo-alignment First, prepare a glass substrate with electrodes (length: 30 mm, width: 50 mm, thickness: 0.7 mm). An ITO electrode having a solid pattern constituting a counter electrode as the first layer is formed on the substrate. On the counter electrode of the first layer, a SiN (silicon nitride) film formed by CVD is formed as the second layer. The film thickness of the second layer SiN film is 500 nm, and it has the function of an interlayer insulating film. On the second layer SiN film, a comb-shaped pixel electrode formed by patterning an ITO film as the third layer is arranged to form two types of pixels, the first pixel and the second pixel. The size of each pixel is 10 mm in length and about 5 mm in width. At this time, the counter electrode of the first layer and the pixel electrode of the third layer are electrically insulated by the action of the SiN film of the second layer.

The pixel electrode of the third layer is a comb-shaped electrode element with a plurality of "U"-shaped electrode elements bent at an inner angle of 160° in the center. The width of each electrode element in the lateral direction is 3μm, and the interval between electrode elements is 6μm. Then each pixel is divided into upper and lower regions by the central curved portion, with a first region on the upper side of the curved portion and a second region on the lower side.

Next, the liquid crystal alignment agents (I12-P) to (I29-P), (I44-P) to (I47-P) and (R-I3-P) were filtered with a filter having an aperture of 1.0 μm, and then applied by spin coating on a glass substrate having the above-mentioned substrate with electrodes and a columnar spacer having a height of 4 μm formed on the back of an ITO film. The coating obtained from the liquid crystal alignment agents (I12-P) to (I29-P) and (R-I3-P) was dried on a heating plate at 80°C for 5 minutes, and then baked in a hot air circulation oven at 230°C for 20 minutes to obtain a polyimide film with a film thickness of 100 nm. Then, the coated surface was irradiated with 500mJ/ ^cm2 of ultraviolet light with a wavelength of 254nm and an extinction ratio of 26:1 through a polarizing plate, and then baked in a hot air circulation oven at 230℃ for 30 minutes to obtain a substrate with a liquid crystal alignment film with a film thickness of 100nm. In addition, the liquid crystal alignment film formed on the substrate with electrodes was subjected to an alignment treatment until the direction of the inner angle that equally divides the above pixel curved portion is perpendicular to the liquid crystal alignment direction, and the liquid crystal alignment film formed on the substrate with columnar spacers was subjected to an alignment treatment until the liquid crystal alignment direction on the substrate with electrodes and the liquid crystal alignment direction on the substrate with columnar spacers became consistent when the liquid crystal unit was manufactured.

The coating obtained from the liquid crystal alignment agent (I44-P) to (I47-P) was dried on a heating plate at 80°C for 5 minutes, and then the coating surface was irradiated with 500mJ/ ^cm2 of ultraviolet light with a wavelength of 254nm with an extinction ratio of 26:1 through a polarizing plate, and then baked in a hot air circulation oven at 230°C for 30 minutes to obtain a substrate with a liquid crystal alignment film with a film thickness of 100nm. Next, a sealant was applied to one side of the glass substrate with a liquid crystal alignment film in the above set, and the other substrate was bonded so that it faced the liquid crystal alignment film surface, and the sealant was cured to form a vacuolar cell. Liquid crystal MLC-3019 (Merck) was injected into the cell by reduced pressure injection method, and the injection port was sealed to obtain an FFS-driven liquid crystal display element. After that, the obtained liquid crystal unit was heated at 120°C for 1 hour, and after being left overnight, the liquid crystal display element was observed with a polarizing microscope to confirm that all liquid crystals were uniformly aligned.

2-2. Evaluation of liquid crystal display element [Evaluation of voltage retention rate] Two glass substrates with ITO electrodes (length: 40mm, width: 30mm, thickness: 1.1mm) were prepared. A liquid crystal alignment film with a thickness of 100nm was made on the ITO surface in the same procedure as in 2-1 above. Bead spacers with a diameter of 4μm (silk balls made by Sunward Catalyst Chemicals, SW-D1) were applied on the liquid crystal alignment film surface of one substrate. Next, a sealant (XN-1500T made by Mitsui Chemicals) was applied around. Next, the side of the other substrate with the liquid crystal alignment film formed on it was used as the inner side, and after bonding with the aforementioned substrate, the sealant was hardened to produce a hollow cell. Liquid crystal MLC-3019 (trade name of Merck) was injected into the cell by reduced pressure injection method to produce a liquid crystal display element. Next, the liquid crystal display element was placed in an oven at 80°C under LED light for 200 hours, and then naturally cooled to room temperature at room temperature. Thereafter, the same evaluation procedure as in 1-2 above was performed. The evaluation results are shown in Table 3.

3-1. Preparation of FFS type liquid crystal display element by friction alignment First, on each surface of the same pair of glass substrates as in 2-1 above, the liquid crystal alignment agent (I30-U) to (I37-U), (I50-U), (R-I4-U) filtered by a filter with an aperture of 1.0μm was applied using an inkjet coating device (HIS-200, manufactured by Hitachi Industrial Equipment Technology Co., Ltd.). The coating was carried out under the conditions of a coating area of 70×70mm, a nozzle pitch of 0.423mm, a scanning pitch of 0.5mm, a coating speed of 40mm/second, and a control of 60 seconds from coating to drying. Next, after drying on a hot plate at 80°C for 5 minutes, it was baked in a hot air circulation oven at 230°C for 20 minutes to obtain a polyimide film with a thickness of 100 nm. The polyimide film was rubbed with a rayon cloth (roller diameter: 120 mm; roller rotation number: 500 rpm; moving speed: 30 mm/sec; pressing length: 0.3 mm; rubbing direction: 10° tilted direction for the third layer of IZO comb electrodes), and then cleaned in pure water by ultrasonic irradiation for 1 minute to remove water droplets. Afterwards, it was dried at 80°C for 15 minutes to obtain a substrate with a liquid crystal alignment film. These two substrates with liquid crystal alignment films are grouped together, and a sealant is printed on the substrate in the shape of a residual liquid crystal injection port. Another substrate is bonded to face the liquid crystal alignment film surface, and the rubbing direction becomes antiparallel. Afterwards, the sealant is hardened to produce a hollow cell with a cell gap of 4μm. Liquid crystal MLC-7026-100 (Merck) is injected into the hollow cell by the reduced pressure injection method, and the injection port is sealed to obtain a FFS liquid crystal display element. Afterwards, the obtained liquid crystal display element is heated at 120°C for 1 hour, and after being placed at 23°C overnight, it is used for the evaluation of residual image evaluation. After observing the obtained liquid crystal display element with a polarizing microscope, it is confirmed that all liquid crystals are uniformly aligned.

3-2. Evaluation of liquid crystal display element [Voltage retention evaluation] Using the same liquid crystal alignment film as in 3-1 above, except for MLC-7026-100, the evaluation was performed in the same procedure as in 2-2 above. The evaluation results are shown in Table 3.

4-1. Preparation of VA-type liquid crystal display element by light alignment: Prepare 2 glass substrates similar to those in 1-1 above, spin-coat the liquid crystal alignment agent (V48-P) or (V49-P) on each substrate, heat-treat at 80°C for 90 seconds on a heating plate, and heat-treat at 200°C for 40 minutes in a heat cycle type dust-free oven to obtain an ITO substrate with a film thickness of 100nm and a liquid crystal alignment film. Next, expose the above substrate to linearly polarized UV light at an incident angle of 40° perpendicular to the substrate surface. The added exposure amount is 20mJ/ ^cm2 . After exposure, assemble the unit with the two substrates so that the exposed alignment layer faces the inside of the unit, and adjust the substrates so that the alignment directions are parallel to each other. Next, inject liquid crystal MLC-7067 (Merck). Afterwards, the device was annealed at about 90°C for 10 minutes, cooled to room temperature, and then used for afterimage evaluation. The obtained liquid crystal display device was observed with a polarizing microscope, confirming that all liquid crystals were uniformly aligned.

4-2. Evaluation of liquid crystal display element [Evaluation of voltage retention rate] The liquid crystal display element prepared in 4-1 above was placed in an oven at 80°C under LED light for 200 hours, and then naturally cooled to room temperature. The evaluation was performed in the same procedure as 1-2 above. The evaluation results are shown in Table 3. Table 3 shows the evaluation results of the liquid crystal alignment agents of the embodiments of the present invention in Examples 1 to 50, and Examples 51 to 56 show the evaluation results of the liquid crystal alignment agents of the comparative examples.

[Industrial Availability]

The liquid crystal alignment agent of the present invention is useful for forming a liquid crystal alignment film in various liquid crystal display elements such as vertical alignment type or FFS drive type. The liquid crystal display element having the liquid crystal alignment agent of the present invention can be effectively applied to various devices, such as clocks, portable video games, word processors, notebook computers, car navigation systems, camcorders, PDAs, digital cameras, mobile phones, smart phones, various monitors, liquid crystal televisions, information displays and other display devices. Furthermore, it is not limited to the above, and can be used for liquid crystal alignment films for phase difference films, liquid crystal alignment films for scanning antennas or liquid crystal array antennas, or liquid crystal alignment films for liquid crystal dimming elements of the through-scattering type, or for purposes other than these, such as protective films for color filters, flexible display gate insulating films, and substrate materials. Moreover, the entire contents of the specification, patent application scope, drawings, and invention abstract of Japanese Patent Application No. 2019-127053 filed on July 8, 2019 are cited here as the disclosure contents of the specification of the present invention.

Claims (15)

A liquid crystal alignment agent, characterized by containing the following components (A) and (B); component (A): at least one polymer selected from the group consisting of polyimide polymers, polyorganosiloxanes, polymers of monomers having polymerizable unsaturated bonds, and cellulose polymers; component (B): a compound having a structure having two or more rings connected directly or via a linking group, or a steroid skeleton, and having at least one group represented by the following formula (b-1) to (b-5), or having at least two groups represented by the following formula (b-6), and having a molecular weight of 2000 or less, and represented by the following formula (3-1) or the following formula (3-2);

(However, R ₂ , R _4a , R _4b , R ₅ , and R ₆ each independently represent a hydrogen atom or an alkyl group having 1 to 20 carbon atoms; * represents a bonding hand)

(However, _B1 represents a structure selected from the aforementioned formulae (b-1) to (b-6), _B2 represents a structure selected from the aforementioned formulae (b-1) to (b-5); _L1 represents the following formula (1L-1) or (1L-2); _L2 represents a single bond, the following formula (2L-1), or a divalent group selected from the group consisting of _-CH2- , -CH( _CH3 )-, -C( _CH3 ) _2- , -( _CH2 ) _n- (n represents an integer of 2 to 20) and -NR- (R represents a hydrogen atom or a methyl group) (hereinafter referred to as a linking group (2a)); and any _CH2 in the aforementioned -( _CH2 ) _n- may be substituted by -O-, -CH( _CH3 )-, -C( _CH3 ) _2- , -CO- or -NR-; _AL1 and _AL2 each independently represent * _-Cy1 -Z ₁ or *-Cy ₂ ; m1 represents an integer of 1 to 4; m2 represents an integer of 1 to 2; Cy ₁ represents a structure in which two or more rings are linked directly or via a linking group; Cy ₂ represents a group having a steroid skeleton; Z ₁ represents a linear or branched hydrocarbon group having 3 or more carbon atoms);

(However, *1 represents a bonding partner with AL ₁ , and *2 represents a bonding partner with B ₁ ; n1 represents an integer of 1 to 2, and n2 represents an integer of 1 to 4; A ₁₁ and A ₁₂ each independently represent a single bond, -O-, or a linking group (2a); when A ₁₂ exists in plural numbers, the plural A _12s may be the same or different; A ₂₁ and A ₂₂ each independently represent a linking group (2a) (except -NR-); _As11 represents a single bond, -O-, -CO-, or a linking group (2a); _As12 represents a single bond, -CO-, or a linking group (2a) (except -NR-))

(However, *1 indicates a bond with B ₂ , and *2 indicates a bond with AL ₂ ; _As2 and _As11 are synonymous). The liquid crystal alignment agent of claim 1, wherein the polyimide polymer comprises a polymer (A-1) having at least one repeating unit selected from the group consisting of a repeating unit represented by the following formula (1) and a repeating unit represented by the following formula (2);

(However, _X1 represents a tetravalent organic group; _Y1 represents a divalent organic group; _R1 represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms; _Z11 and _Z12 each independently represent a hydrogen atom, an alkyl group having 1 to 10 carbon atoms which may have a substituent, an alkenyl group having 2 to 10 carbon atoms which may have a substituent, an alkynyl group having 2 to 10 carbon atoms which may have a substituent, a tert-butoxycarbonyl group, or a 9-fluorenylmethoxycarbonyl group). The liquid crystal alignment agent of claim 2, wherein the above _X1 is a tetravalent organic group selected from the group consisting of the following formulas (4a) to (4n), the following formula (5a) and the following formula (6a);

(However, x and y represent a single bond, -O-, -CO-, -COO-, an alkanediyl group having 1 to 5 carbon atoms, 1,4-phenylene, -SO-, or -NRCO- (R represents a hydrogen atom or a methyl group); Z ¹ to Z ⁶ each independently represent a hydrogen atom, a methyl group, an ethyl group, a propyl group, a chlorine atom, or a benzene ring; j and k represent an integer of 0 or 1; m represents an integer of 1 to 5; and * represents a bond). In the liquid crystal alignment agent of claim 3, the aforementioned _X1 is a tetravalent organic group selected from the group consisting of the aforementioned formulae (4a) to (4n), (5a) and the aforementioned formula (6a), and the content of one or more repeating _units selected from the group consisting of the repeating units represented by the aforementioned formula (1) and the repeating units represented by the aforementioned formula (2) in which Y1 is a divalent organic group is 5 mol% or more relative to all repeating units when expressed in total. As in claim 1, the liquid crystal alignment agent, wherein the aforementioned component (B) is the compound represented by the aforementioned formula (3-1). The liquid crystal alignment agent of claim 1 or 5, wherein _Z1 is a linear or branched alkyl group having 3 to 20 carbon atoms, a linear or branched fluoroalkyl group having 3 to 20 carbon atoms, a linear or branched alkoxy group having 3 to 20 carbon atoms, or a linear or branched alkyl ester group having 3 to 20 carbon atoms. The liquid crystal alignment agent of any one of claims 1 to 5, wherein the Cy ₁ is represented by the following formula (Rn);

In formula (Rn), X each independently represents a single bond, -O-, -CO-, -COO-, -NR ^b -, -CONR ^b - (R ^b represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or a protecting group), an alkanediyl group having 1 to 10 carbon atoms, or a divalent group in which at least one methylene group of an alkanediyl group having 1 to 10 carbon atoms is substituted by -O-, -CO-, -COO-, -NR ^b - or -CONR ^b -; m is 2 to 6; G each independently represents a benzene ring, a naphthalene ring or a cyclohexane ring; and * represents a bond. The liquid crystal alignment agent of any one of claims 1 to 5, wherein the component (B) is a compound represented by any one of the following formulas (b-1) to (b-8);

A liquid crystal alignment agent as claimed in any one of claims 1 to 5, wherein the aforementioned component (A) contains a polyimide polymer and at least one polymer selected from the group consisting of polyorganosiloxane, a polymer of a monomer having a polymerizable unsaturated bond, and a cellulose polymer. A liquid crystal alignment agent as claimed in any one of claims 1 to 5, wherein the aforementioned component (A) contains a polyimide polymer and also contains a polyorganosiloxane. A liquid crystal alignment agent as claimed in any one of claims 1 to 5, wherein the content of the aforementioned component (B) is 0.1 to 40 parts by mass per 100 parts by mass of the aforementioned component (A). A liquid crystal alignment agent as claimed in any one of claims 1 to 5, wherein the liquid crystal alignment agent contains an organic solvent, and as the organic solvent, the organic solvent contains at least one good solvent selected from the group consisting of N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, dimethylsulfoxide, γ-butyrolactone, γ-valerolactone, 1,3-dimethyl-2-imidazolidinone, methyl ethyl ketone, cyclohexanone, cyclopentanone, N,N-dimethyllactamide, 3-methoxy-N,N-dimethylpropaneamide and 3-butoxy-N,N-dimethylpropaneamide. As claimed in claim 12, the liquid crystal alignment agent further contains at least one weak solvent selected from the group consisting of diisobutyl carbinol (Carbinol), propylene glycol monobutyl ether, propylene glycol diacetate, diethylene glycol diethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol dimethyl ether, 4-hydroxy-4-methyl-2-pentanone, ethylene glycol monobutyl ether, ethylene glycol monobutyl ether acetate and diisobutyl ketone. A liquid crystal alignment film, which is obtained from a liquid crystal alignment agent as described in any one of claims 1 to 13. A liquid crystal display element, comprising a liquid crystal alignment film as claimed in claim 14.