TW201906990A - Liquid crystal alignment agent, liquid crystal alignment film, and liquid crystal display element - Google Patents

Abstract

Provided are: a liquid crystal aligning agent which has excellent whitening resistance and coating film uniformity; a liquid crystal alignment film; and a liquid crystal display element. A liquid crystal aligning agent which is characterized by containing at least one polymer that is selected from the group consisting of polyimide precursors having a partial structure represented by formula [U] and a side chain structure selected from the group consisting of structures of formulae [S1] and [S2] and a steroid skeleton and polyimides that are imidized products of the polyimide precursors. (In the formulae, the symbols are as defined in the description.).

Description

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

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

Liquid crystal display elements are widely used as thin and light-weight display devices. Generally, in this liquid crystal display element, a liquid crystal alignment film is used in order to control the alignment state of the liquid crystal. In recent years, liquid crystal display elements have been widely used in large-screen liquid crystal televisions or high-definition portable applications (display portions of digital cameras or mobile phones). Compared with the past, the substrates used have become larger, and the unevenness of the substrate segments has become larger. . Even in this case, from the viewpoint of display characteristics, it is necessary to form a liquid crystal alignment film uniformly for a large substrate or a step.

In addition, liquid crystal alignment films are required to control the alignment state of liquid crystals (also referred to as liquid crystal alignment), reliability in liquid crystal display elements, and electrical characteristics such as residual image characteristics. As a liquid crystal alignment film, a polyimide-based polymer of polyamic acid or soluble polyimide has been conventionally used (see, for example, Patent Document 1). [Prior Art Literature] [Patent Literature]

[Patent Document 1] International Publication WO2009 / 093709

[Problems to be Solved by the Invention]

However, the polyimide-based polymer used in the conventional liquid crystal alignment film may not be sufficiently soluble in a solvent. When a liquid crystal alignment agent is coated on a substrate, a polymer is formed on the substrate (also called whitening). ). This phenomenon called whitening has become a serious problem as the production line for producing liquid crystal alignment films has become larger. This is because the liquid crystal alignment agent contains moisture in the atmosphere and the solubility of the polymer decreases.

In addition, when whitening occurs, the uniformity of the coating film of the liquid crystal alignment film is reduced, and uniform coating film properties cannot be obtained, which becomes a display defect in a liquid crystal display element.之 An object of the present invention is to provide a liquid crystal alignment agent excellent in whitening resistance and coating film uniformity, and a liquid crystal alignment film excellent in liquid crystal alignment. In addition, a liquid crystal display element having the liquid crystal alignment film is provided. [Means to solve the problem]

The present inventors have found that a liquid crystal alignment agent containing a polymer having a specific structure is extremely effective in achieving the above-mentioned object, and completed the present invention. That is, this invention has the following skilled person. (1) A liquid crystal alignment agent, which is characterized by comprising: a structure selected from a partial structure represented by the following formula [U], and a structure selected from the structures represented by the following formulas [S1], [S2], and a structure having a steroid skeleton A polyimide precursor of at least one side chain structure and a polymer of at least one kind of polyimide, Y ¹ is a single bond, -O-, -S-, -COO- or -OCO-, and K ¹ and K ² are each independently a -CH ₂ -group, -CHR ^1a -group (R ^1a represents -OH group or 1 Valence organic group), any one of K ¹ and K ² may be substituted by a -C (O) group, R ³ and R ⁴ are each independently an alkylene group having 1 to 7 carbon atoms, * represents a group other than Bonding site. X ¹ and X ^{2 are} independently a single bond,-(CH ₂ ) _a- (a is an integer from 1 to 15), -CONH-, -NHCO-, -CON (CH ₃ )-, -NH-, -O- , -COO-, -OCO- or-((CH ₂ ) _a1 -A ₁ ) _m1- (A1 of the plural each independently represents an integer of 1 to 15; A _{1 of the} plural independently represents an oxygen atom or COO-, m ₁ G ¹ and G ^{2 are} independently a divalent aromatic group having 6 to 12 carbon atoms or a divalent cyclic group selected from a divalent alicyclic group having 3 to 8 carbon atoms, and the aforementioned cyclic group Any of the above hydrogen atoms may be an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a fluorine-containing alkyl group having 1 to 3 carbon atoms, a fluorine-containing alkoxy group having 1 to 3 carbon atoms or Fluorine atom substitution, m and n are independently integers from 0 to 3. The total of these is 1 to 4, R ¹ is an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms or 2 to 2 carbon atoms. An alkoxyalkyl group of 20, in which any hydrogen atom may be substituted by a fluorine atom. X ³ represents a single bond, -CONH-, -NHCO-, -CON (CH ₃ )-, -NH-, -O-, -CH ₂ O-, -COO- or OCO-, and R ² is a carbon number of 1 ~ An alkyl group of 20 or an alkoxyalkyl group having 2 to 20 carbon atoms. Any hydrogen atom in these groups may be substituted by a fluorine atom. [Inventive effect]

The liquid crystal alignment agent of the present invention can obtain a liquid crystal alignment film having excellent whitening resistance and coating film uniformity, and excellent liquid crystal alignment. A liquid crystal display element having a liquid crystal alignment film obtained from the liquid crystal alignment agent of the present invention is excellent in display quality. Suitable for various display devices. [Form of Implementing Invention]

<Specific partial structure> The liquid crystal alignment agent of the present invention contains a partial structure represented by the formula [U] (also referred to as a specific partial structure), and has at least one selected from the formulas [S1], [S2], and a steroid skeleton. Polymers with side chains (also known as specific side chains). The meanings of Y ¹ , Y ² , K ¹ , K ² , R ³ , R ⁴ , and * in the formula [U] are as described above.

When K ¹ and K ² are -CHR ^1a -groups, a monovalent organic group constituting R ^1a includes a hydrocarbon group; a hydrocarbon group having a hydroxyl group, a carboxyl group, a hydroxyl group, a mercapto group, or a carboxyl group; Hydrocarbyl groups linked by bonding groups such as amine bonds; hydrocarbyl groups containing silicon atoms; halogenated hydrocarbyl groups; amine groups; inert groups in which the amine group is protected by a urethane-based protecting group such as a third butoxycarbonyl group. The hydrocarbon group herein may be any of a straight chain, a branched chain, or a cyclic chain, and may be a saturated hydrocarbon or an unsaturated hydrocarbon. In addition, a part of the hydrogen atom of the hydrocarbon group may be substituted by a carboxyl group, a hydroxyl group, a mercapto group, a silicon atom, a halogen atom, or the like, or may be connected by a bonding group such as an ether bond, an ester bond, or a amide bond.

The alkylene group having 1 to 7 carbon atoms constituting R ³ and R ⁴ may be any of a straight chain, a branched chain, and a cyclic chain. Specific examples include methyl, ethyl, n-propyl, isopropyl, methylcyclopropyl, 1-methyl-cyclopropyl, 2-methyl-cyclopropyl, 1,1-dimethyl-n-propyl, 1,2-dimethyl-n-propyl, 2,2-dimethyl-n-propyl, 1-ethyl-n-propyl Propyl, 1,2-dimethyl-cyclopropyl, 2,3-dimethyl-cyclopropyl, 1-ethyl-cyclopropyl, 2-ethyl-cyclopropyl, 1 , 1,2-trimethyl-n-propyl, 1,2,2-trimethyl-n-propyl, 1-ethyl-1-methyl-n-propyl, 1-ethyl 2-methyl-n-propyl, 2-n-propyl-cyclopropyl, 1-isopropyl-cyclopropyl, 2-isopropyl-cyclopropyl, 1,2 , 2-trimethyl-cyclopropyl, 1,2,3-trimethyl-cyclopropyl, 2,2,3-trimethyl-cyclopropyl, 1-ethyl-2-methyl -Cyclopropane, 2-ethyl-1-methyl-cyclopropane, 2-ethyl-2-methyl-cyclopropane, and 2-ethyl-3-methyl-cyclopropane Base etc.

Among them, Y ¹ and Y ² in the formula [U] are preferably -O-, -COO-, or -OCO- from the viewpoint of the polymer supply property. Among K ¹ and K ² , a -CH ₂ -group, a -CH (OH)-group, a -CO- group, a -CH (CH ₃ )-group, and a -CH (O-Boc)-group are preferred. . "Boc" means tert-butoxycarbonyl. Among R ³ and R ⁴ , methyl, ethyl, and n-propyl are preferred.

The partial structure represented by the formula [U] is preferably the following formula [U-Ar]. In the above-mentioned [U-Ar], Y ¹ , Y ² , K ¹ , K ² , R ³ and R ⁴ are the same as Y ¹ , Y ² , K ¹ , K ² , R ³ and R in the aforementioned formula (U). ^{4 is} synonymous, * indicates a site bonded to another base.

<Specific side chain structure> The specific polymer further has at least one specific side chain structure selected from the group consisting of the following formulas [S1], [S2], and a steroid skeleton. The meanings of X ¹ , X ² , G ¹ , G ² , R ¹ , m, and n in the formula [S1] are as described above.

Among X ¹ and X ² , from the viewpoint of availability of raw materials or ease of synthesis, a single bond,-(CH ₂ ) _a- (a is 1 to 15), -O-, -CH ₂ O- or COO- is better. More preferably, it is a single bond,-(CH ₂ ) _a- (a is 1 to 10), -O-, -CH ₂ O-, or COO-.

Examples of the divalent aromatic group having 6 to 12 carbon atoms in G ¹ and G ² include phenylene, biphenylene, and naphthyl. Examples of the divalent alicyclic group having 3 to 8 carbon atoms include a cyclopropyl group and a cyclohexyl group. Among G ¹ and G ² , phenylene, phenylene, naphthyl, cyclopropyl, or cyclohexyl are preferred. Among R ¹ , an alkyl group having 1 to 20 carbon atoms or an alkoxy group having 1 to 20 carbon atoms is more preferred.

Preferred specific examples of the formula [S1] include the following formulas [S1-x1] to [S1-x7].

In the formulae [S1-x1] to [S1-x7], R ¹ is an alkyl group having 1 to 20 carbon atoms, and X ^{p is-} (CH ₂ ) _a- (a is an integer from 1 to 15), -CONH-, _{-NHCO-, -CON (CH 3) -} , - NH -, - O -, - CH 2 O -, - COO-, or -OCO-. A ₁ is -O- or -COO- * (but with "*" bond and (CH ₂ ) _a2 bond), A ₂ is -O- or * -COO- (but with "*" Bond with (CH ₂ ) _a2 ), a ₁ and a ₃ are each independently 0 or 1, a ₂ is 2-10, and Cy is 1,4-cyclohexyl or 1,4-phenylene .

The definitions of X ³ and R ² in the formula [S2] are as described above. Among them, X ³ is preferably -CONH-, -NHCO-, -O-, -CH ₂ O-, -COO-, or OCO- from the viewpoint of liquid crystal alignment. R ² is preferably an alkyl group having 3 to 20 carbon atoms or an alkoxyalkyl group having 2 to 20 carbon atoms from the viewpoint of liquid crystal alignment.

The structure having a steroid skeleton can be represented by the following formula [S3]. In the formula [S3], X ⁴ is -CONH-, -NHCO-, -O-, -COO-, or OCO-, and R ³ represents the aforementioned structure having a steroid skeleton. Preferred specific examples of the formula [S3] include the following formula [S3-x]. In the formula, * indicates a bonding position.

The formula [S3-x] is preferably the following combination. Formula [X1] -Form [Col1]-[G1], Formula [X1] -Form [Col1]-[G2], Formula [X1] -Form [Col2]-[G1], Formula [X1] -Form [Col2 ]-[G2], formula [X1] -form [Col3]-[G2], formula [X1] -form [Col4]-[G2], formula [X1] -form [Col3]-[G1], formula [ X1] -form [Col4]-[G1], formula [X2] -form [Col1]-[G2], formula [X2] -form [Col2]-[G2], formula [X2] -form [Col1]- [G2], formula [X2] -form [Col2]-[G2], formula [X2] -form [Col1]-[G1], formula [X2] -form [Col2]-[G1], formula [X2] -Formula [Col3]-[G2], Formula [X2] -Form [Col4]-[G2], Formula [X2] -Form [Col1]-[G1], Formula [X2] -Form [Col4]-[G1 ].

Specific examples of the structure having a steroid skeleton include a steroid compound described in paragraph [0024] of Japanese Patent Application Laid-Open No. 4-281427, a structure after removing a hydroxyl group, and a steroid compound described in paragraph [0030] to remove acid chloride. The structure after the compound group, the structure after the steroid compound described in paragraph [0038], the structure after the amine group is removed, the structure after the halogen compound is removed from the steroid compound described in paragraph [0042], or Japanese Patent Application Laid-Open No. 8-146421 Structures described in paragraphs [0018] to [0022].

<Specific polymer> The specific polymer in the present invention is a polymer selected from at least one of polyimide precursors and polyimide (collectively referred to as polyimide polymers). Among them, polyfluorene imide that is a polyfluorene imide precursor obtained by reacting a diamine component with a tetracarboxylic acid component or a fluorimidate thereof is preferred. The polyfluorene imide precursor is represented by the following formula [A].

In Formula [A], R ¹ is a tetravalent organic group, R ² is a divalent organic group, A ¹ and A ² are each independently a hydrogen atom or an alkylene group having 1 to 5 carbon atoms, and A ³ and A ⁴ are each independently Is a hydrogen atom, an alkylene group or an ethanoyl group having 1 to 5 carbon atoms, and n is a positive integer. Examples of the diamine component include diamines having two primary or secondary amine groups in the molecule. Examples of the tetracarboxylic acid component include tetracarboxylic acid, tetracarboxylic dianhydride, tetracarboxylic acid dihalide, tetracarboxylic acid dialkyl ester, and tetracarboxylic acid dialkyl dihalide.

In order to obtain a polyamino acid in which A ¹ and A ² in formula [A] are hydrogen atoms, the diamine having two first- or second-order amine groups, tetracarboxylic acid, or Tetracarboxylic anhydride is obtained by reaction. When the polyamide acid alkyl ester in order to obtain the formula [A] in the A ¹ and A ² is an alkylene group having a carbon number of 1 to 5, and by making available the diamine with a tetracarboxylic acid dihalide, tetrakis It is obtained by reacting a dialkyl carboxylate or a dialkyl tetracarboxylic acid dihalide. Further, an alkylene group having 1 to 5 carbon atoms of A ¹ and A ² represented by the formula [A] may be introduced into the polyamic acid obtained by the method described above.

Specific aspects of the specific polymer include at least one of a structural unit including a partial structure of the aforementioned formula [U], a structure selected from the aforementioned formulas [S1], [S2], and a structure having a steroid skeleton. A polymer (hereinafter also referred to as a copolymer) having a structural unit of a side chain structure, a polymer including a structural unit having a partial structure of the aforementioned formula [U], and a polymer including a structural unit selected from the aforementioned formulas [S1], [S2] And a polymer of a structural unit having at least one side chain structure of a steroid skeleton (hereinafter also referred to as a polymer blend).

The method for introducing a part of the structure of the formula [U] into a polymer is not particularly limited, but a diamine having a structure of the formula [U], specifically, a diamine represented by the following formula [U-1] is used. Part of the raw material is preferred.

In the formula [U-1], Y ^A represents an organic group having the structure of the aforementioned formula [U], and A ¹ and A ² each independently represent a hydrogen atom or an alkylene group having 1 to 5 carbon atoms. More specifically, a diamine represented by the following formula [Ua] is preferred.

In Formula [Ua], Y ¹ and Y ² are each independently a single bond, -O-, -S-, -COO-, or -OCO-. K ¹ and K ² each independently represent a -CH ₂ -group or a -CHR ^1a -group (R ^1a represents an -OH group or a monovalent organic group), and either of K ¹ and K ² may be substituted Is -C (O) group. R ³ and R ⁴ are each independently an alkylene group having 1 to 7 carbon atoms. Any hydrogen atom of the benzene ring may be substituted with a monovalent organic group. A ¹ and A ² each independently represent a hydrogen atom or an alkylene group having 1 to 5 carbon atoms.

Specific structures of the amine [Ua] include the following formulas [U-1a] to [U-6a].

In the above formulas [U-1a] to [U-6a], A ¹ to A ² each independently represent a hydrogen atom or an alkylene group having 1 to 5 carbon atoms, and a Boc group represents a third butoxycarbonyl group.

More specific examples of the diamine [Ua] include the following formulas [UM-1] to [UM-13].

The method of introducing at least one type of side chain structure selected from the structures of the formulae [S1] and [S2] and the structure having a steroid skeleton into the polymer is not particularly limited, but a method having a structure selected from the formulae [S1], A diamine having a structure of [S2] and a side chain structure having a structure of a steroid skeleton is preferably used as a part of the raw material.

Specifically, it is preferable to use a diamine represented by the following formula [S1-a] as a part of a raw material.

In the formula [S1-a], B is the aforementioned formula [S1], [S2] or [S3], and A ¹ and A ² are each independently a hydrogen atom or an alkylene group having 1 to 5 carbon atoms, especially a hydrogen atom Or an alkylene group having 1 or 2 carbon atoms is preferred. m is 1 to 4, and particularly, from the viewpoint of easy synthesis, 1 is preferred. The preferred examples of the formulas [S1] to [S3] are as described above.

When the specific polymer is the aforementioned copolymer, the amount of the diamine represented by the aforementioned formula [Ua] and the diamine represented by the aforementioned formula [S1-a] when the copolymer is obtained are each 100 mol in the total diamine component. Of these, 1 to 99 mol% is preferable, and 2 to 98 mol% is more preferable. In this case, the total amount of the diamine represented by the aforementioned formula [Ua] and the diamine represented by the aforementioned formula [S1-a] is from 100 to 100 mole% of the total diamine component. More preferably, it is preferably 10 to 100 mole%, and particularly preferably 20 to 100 mole%.

When the specific polymer is the aforementioned blend, the amount of the diamine represented by the aforementioned formula [Ua] is 100 mol% of the diamine component of the polymer used to constitute the polymer containing the residue of the aforementioned formula [Ua] From the viewpoint of improving the albino resistance, it is preferably 5 mol% or more, more preferably 10 mol% or more, and still more preferably 20 mol% or more. The amount of the diamine used in the formula [S1-a] is 100 mol% of the diamine component of the polymer used to constitute the polymer containing the residue of the formula [S1-a] in order to increase the liquid crystal. From the viewpoint of alignment, 1 mol% or more is preferable, 2 mol% or more is more preferable, and 5 mol% or more is more preferable. Particularly preferred examples include 20 mol% or more.

The diamine of the aforementioned formula [Ua] and the diamine of the aforementioned formula [S1-a] are formulated with the solubility of a specific polymer in a solvent or the coatability of a liquid crystal alignment agent, the liquid crystal alignment property when used as a liquid crystal alignment film, and voltage holding It can use 1 type or a mixture of 2 or more types in characteristics such as rate, accumulated charge, and the like. (2) The diamine component when a specific polymer is obtained may use a diamine other than the diamine of the formula [Ua] and the diamine of the formula [S1-a] (also referred to as other diamines).

Specifically, the diamine described in paragraph [0169] of International Publication WO2015 / 046374, the diamine having a carboxyl group or hydroxyl group described in paragraphs [0171] to [0172], and paragraphs [0173] to [0188] The diamine having a nitrogen-containing heterocyclic ring or the diamine having a nitrogen-containing structure described in paragraph [0050] of Japanese Patent Application Laid-Open No. 2016-218149, 1,3-bis (3-aminopropyl)- Organic silicon containing 1,1,3,3-tetramethyldisilazane, 1,3-bis (4-aminobutyl) -1,1,3,3-tetramethyldisilaxane The diamine of oxane is used as a liquid crystal display device to improve the response speed of liquid crystals. The diamine having a site for generating radicals in a side chain as described in International Publication No. WO2015 / 033921 has a co-polymer that can be formed by light irradiation. A diamine or the like of a valent bond functional group (also referred to as a photoreactive group).

More specific examples include m-phenylenediamine, p-phenylenediamine, 4,4'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminobiphenyl, 3,3'-difluoro-4,4'-diaminobiphenyl, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether, 4,4'-di Aminodiphenylamine, N-methyl (4,4'-diaminodiphenyl) amine, 4,4'-diaminobenzophenone, 1,4-diaminonaphthalene, 2, 6-Diaminonaphthalene, 1,2-bis (4-aminophenyl) ethane, 1,3-bis (4-aminophenyl) propane, 1,4-bis (4-aminophenyl) ) Butane, 1,4-bis (4-aminophenoxy) benzene, 1,4-bis (4-aminophenyl) benzene, 1,3-bis (4-aminophenyl) benzene, 1,4-bis (4-aminobenzyl) benzene, 1,3-bis (4-aminophenoxy) benzene, 4,4 '-[1,4-phenylenebis (methylene) ] Diphenylamine, 1,4-phenylenebis [(4-aminophenyl) methanone], 1,4-phenylenebis (4-aminobenzoate), bis (4-amino (Phenyl) terephthalate, bis (4-aminophenyl) isophthalate, N, N '-(1,4-phenylene) bis (4-aminobenzamide) ), N, N'-bis (4-aminophenyl) p-xylylenediamine, N, N'-bis (4-aminophenyl) m-xylylenediamine, 9,10-bis ( 4-aminophenyl) anthracene 2,2'-bis [4- (4-aminophenoxy) phenyl] propane, 2,2'-bis (4-aminophenyl) propane, 1,3-bis (4-aminobenzene Oxy) propane, 1,4-bis (4-aminophenoxy) butane, 1,5-bis (4-aminophenoxy) pentane, 1,6-bis (4-aminobenzene Oxy) hexane, 1,7-bis (4-aminophenoxy) heptane, 1,8-bis (4-aminophenoxy) octane, 1,9-bis (4-amine (Phenoxy) nonane, 1,10- (4-aminophenoxy) decane, bis (4-aminocyclohexyl) methane, 1,3-diaminopropane, 1,4-diamine Butane, 1,5-diaminopentane, 1,6-diaminohexane, 2,4-diaminobenzoic acid, 2,5-diaminobenzoic acid, or 3,5-diamino Benzoic acid, 4,4'-diaminobiphenyl-3-carboxylic acid, 4,4'-diaminodiphenylmethane-3-carboxylic acid, 4,4'-diaminodiphenylethyl Alkane-3-carboxylic acid, 4,4'-diaminobiphenyl-3,3'-dicarboxylic acid, 4,4'-diaminobiphenyl-2,2'-dicarboxylic acid, 3 , 3'-diaminobiphenyl-4,4'-dicarboxylic acid, 3,3'-diaminobiphenyl-2,4'-dicarboxylic acid, 4,4'-diaminodiamine Phenylmethane-3,3'-dicarboxylic acid, 4,4'-diaminodiphenylethane-3,3'-dicarboxylic acid, 4,4'-diaminodiphenyl ether-3, 3'-two Acid, 2,6-diaminopyridine, 3,4-diaminopyridine, 2,4-diaminopyrimidine, 3,6-diaminocarbazole, N-methyl-3,6-diamine Carbazole, 1,4-bis- (4-aminophenyl) -piperazine, 3,6-diaminoacridine, N-ethyl-3,6-diaminocarbazole, N-benzene -3,6-diaminocarbazole, N, N'-bis (4-aminophenyl) -benzidine, N, N'-bis (4-aminophenyl) -N, N'- Dimethylbenzidine, a compound represented by each of the following formulae (D-2-1) to (D-2-8), and diamines whose amine groups are secondary amine groups.

The other diamines of the present invention can be used in combination with the solubility of the polymer of the present invention in a solvent or the applicability of a liquid crystal alignment agent, liquid crystal alignment properties when used as a liquid crystal alignment film, voltage holding ratio, and accumulated charge. 1 type or mixed 2 or more types. When the polymer blend contains another diamine, 100 mol% of the diamine component of the polymer containing the residue of the formula [Ua] in the unit is used. The amount of the diamine may be 20 to 100 mole%.

It is preferable to use a tetracarboxylic dianhydride represented by the following formula [4] as the tetracarboxylic acid component for producing the polymer of the present invention, that is, the polyfluorene-imide-based polymer. In this case, not only the tetracarboxylic dianhydride represented by the formula [4], but also a tetracarboxylic acid, a tetracarboxylic acid dihalide, a tetracarboxylic acid dialkyl, or a tetracarboxylic acid dioxane whose tetracarboxylic acid derivative is used Ester dihalide.

Z represents a structure selected from at least one of the following [4a] to [4k].

In the formula [4a], Z ¹ to Z ⁴ represent a hydrogen atom, a methyl group, an ethyl group, a propyl group, a chlorine atom, or a benzene ring, and each may be the same or different. Preferred specific examples of Z ¹ to Z ⁴ include the following structures [4a-1] and [4a-2].

In Formula [4g], Z ⁵ and Z ⁶ represent a hydrogen atom or a methyl group, and each may be the same or different. In Z in the formula [4], from the viewpoint of ease of synthesis or ease of polymerization reactivity at the time of manufacturing a polymer, it is represented by formulas [4a], [4c] to [4g], or [4k] Tetracarboxylic dianhydride and its tetracarboxylic acid derivative having a structure are preferable. More preferably, it is a structure represented by formula [4a] or formula [4e]-formula [4g]. Particularly preferred are tetracarboxylic dianhydrides and their tetracarboxylic acid derivatives having a structure represented by [4a], formula [4e] or formula [4f]. More preferable specific examples include tetracarboxylic dianhydride having a structure represented by [4a-1], formula [4a-2], formula [4e], and formula [4f], and a tetracarboxylic acid derivative thereof.

The tetracarboxylic acid component represented by the formula [4] in the polymer of the present invention is preferably 1 to 100 mole% of all the tetracarboxylic acid components in 100 mole%. Among them, more preferably 5 to 95 mole%. Still more preferably, it is 20 to 80 mol%. The tetracarboxylic acid component of the present invention is compatible with the solubility of the polymer of the present invention in a solvent or the applicability of a liquid crystal alignment agent, the liquid crystal alignment property when used as a liquid crystal alignment film, a voltage holding ratio, and a stored charge, and can be used. Use 1 type or mixed 2 or more types.

The polyimide-based polymer of the polymer of the present invention may use a tetracarboxylic acid component other than the specific tetracarboxylic acid component. Other tetracarboxylic acid components include the following tetracarboxylic acids, tetracarboxylic dianhydrides, tetracarboxylic dihalides, tetracarboxylic dialkyl esters, or tetracarboxylic dialkyl dihalides.

That is, other tetracarboxylic acid components include 1,2,5,6-naphthalenetetracarboxylic acid, 1,4,5,8-naphthalenetetracarboxylic acid, and 1,2,5,6-anthracenetetracarboxylic acid. , 3,3 ', 4,4'-biphenyltetracarboxylic acid, 2,3,3', 4-biphenyltetracarboxylic acid, bis (3,4-dicarboxyphenyl) ether, 3,3 ', 4,4'-benzophenone tetracarboxylic acid, bis (3,4-dicarboxyphenyl) fluorene, bis (3,4-dicarboxyphenyl) methane, 2,2-bis (3,4 -Dicarboxyphenyl) propane, 1,1,1,3,3,3-hexafluoro-2,2-bis (3,4-dicarboxyphenyl) propane, bis (3,4-dicarboxyphenyl) ) Dimethylsilane, bis (3,4-dicarboxyphenyl) diphenylsilane, 2,3,4,5-pyridinetetracarboxylic acid, 2,6-bis (3,4-dicarboxyphenyl) Pyridine, 3,3 ', 4,4'-diphenylfluorenetetracarboxylic acid, 3,4,9,10-fluorenetetracarboxylic acid or 1,3-diphenyl-1,2,3,4-ring Butane tetracarboxylic acid and the like.

The other tetracarboxylic acid components of the present invention have properties such as the solubility of the polymer of the present invention in a solvent or the coatability of a liquid crystal alignment agent, the liquid crystal alignment property when used as a liquid crystal alignment film, the voltage holding ratio, and the stored charge. You can use 1 type or mixed 2 or more types.

<Method for Producing Specific Polymer> 中 In the present invention, a method for producing a polymer, that is, a polyimide-based polymer is not particularly limited. It is usually obtained by reacting a diamine component with a tetracarboxylic acid component. In general, at least one type of tetracarboxylic acid component selected from the group consisting of tetracarboxylic dianhydride and its derivative of tetracarboxylic acid and one or more types of diamines, A method of reacting a diamine component to obtain polyamic acid. Specifically, a method of polycondensing a tetracarboxylic dianhydride with a diamine of class 1 or 2 to obtain polyamic acid can be used, and dehydration polycondensation of a tetracarboxylic acid with a diamine of class 1 or 2. A method of obtaining polyamic acid by reaction or a method of polycondensing a tetracarboxylic dihalide with a diamine of class 1 or 2 to obtain polyamic acid.

The polymer can be obtained by reacting a tetracarboxylic acid component and a diamine component as described above and, if necessary, a molecular weight modifier. Examples of the molecular weight adjusting agent include acid anhydrides such as maleic anhydride, phthalic anhydride, and iconic anhydride, monoamines such as aniline, cyclohexylamine, and n-butylamine, phenyl isocyanate, and naphthyl isocyanate. Monoisocyanate and so on. The use ratio of the molecular weight modifier is preferably 100 parts by mass or less, more preferably 10 parts by mass or less, based on the total of the tetracarboxylic acid component and the diamine component used.

In order to obtain a polyalkylamino acid alkyl ester, a method of polycondensing a tetracarboxylic acid having a dialkyl esterified carboxylic acid group and a diamine of a first or second order can be used, and the carboxylic acid group can be dialkylated. A method of polycondensing an esterified tetracarboxylic dihalide with a diamine of class 1 or 2 or a method of converting a carboxyl group of a polyamic acid into an ester.

In order to obtain a polyfluorene imine, the method of carrying out the ring-closure of the said polyphosphonic acid or a polyalkylamino acid polyimide can be used. The reaction of the fluorene diamine component and the tetracarboxylic acid component is usually carried out in a solvent. The solvent to be used at this time is not particularly limited as long as it is a polyimide precursor produced by dissolution. Specific examples of the solvent used in the reaction are listed below, but are not limited to these examples.

Examples include N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone or γ-butyrolactone, N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl Methyl sulfene or 1,3-dimethyl-2-imidazolinone. When the solvent solubility of the polyimide precursor is high, methyl ethyl ketone, cyclohexanone, cyclopentanone, 4-hydroxy-4-methyl-2-pentanone, or the following formula [ D-1] ~ solvent represented by formula [D-3].

In formula [D-1], D ¹ represents an alkylene group having 1 to 3 carbon atoms, in formula [D-2], D ² represents an alkylene group having 1 to 3 carbon atoms, and in formula [D-3], D ³ represents an alkylene group having 1 to 4 carbon atoms.

These solvents may be used singly or in combination. Moreover, even if it is a solvent which does not melt | dissolve a polyfluorene imide precursor, as long as the produced | generated polyfluorene imide precursor does not precipitate, you may mix and use it with the said solvent. In addition, the moisture in the solvent will hinder the polymerization reaction and cause the resulting polyfluorene imide precursor to hydrolyze. Therefore, it is preferable to use a solvent that is dehydrated and dried. When the diamine component and the tetracarboxylic acid component are reacted in a solvent, the reaction can be performed at any concentration. However, when the concentration is too low, it becomes difficult to obtain a polymer having a high molecular weight. When the concentration is too high, the viscosity of the reaction solution becomes excessive. High, uniform stirring becomes difficult. Therefore, it is preferably 1 to 50% by mass, and more preferably 5 to 30% by mass. The reaction can be performed at a high concentration in the initial stage, and a solvent is added thereafter.

The polymerization reaction of the polyfluorene imide precursor is a ratio of the total mole number of the diamine component to the total mole number of the tetracarboxylic acid component, and preferably 0.8 to 1.2. As with the usual polycondensation reaction, the closer this mole ratio is to 1.0, the larger the molecular weight of the resulting polyfluorene imide precursor. The polyimide of the present invention is a polyimide obtained by subjecting the aforementioned polyimide precursor to ring closure, and the ring closure rate (also known as amidation rate) of the amido acid group of this polyimide is not necessarily To 100%, it can be adjusted arbitrarily according to the purpose or purpose. The method for performing polyimidization of the polyimide precursor may include heat-imidization by heating the polyimide precursor in a solution state, or adding a catalyst to the solution of the polyimide precursor. Catalyst 醯 imidization.

The temperature at which the polyfluorene imine precursor is thermally fluorinated in the solution is 100 to 400 ° C, preferably 120 to 250 ° C, and the water generated by the fluorene imidization reaction is removed outside the system. Better. The polyimide precursor can be touched by adding an alkaline catalyst and an acid anhydride to the solution of the polyimide precursor, and stirring the polyimide precursor by stirring at -20 ° C to 250 ° C, preferably 0 ° C to 180 ° C. Mediate imidization. The amount of the alkaline catalyst is 0.5 to 30 mol times of the amino acid group, preferably 2 to 20 mol times, and the amount of the acid anhydride is 1 to 50 mol times of the amino acid group, preferably 3 to 30 mol times. Examples of the basic catalyst include pyridine, triethylamine, trimethylamine, tributylamine, and trioctylamine. Among them, pyridine is preferred because it has a moderate basicity required for the reaction. Examples of the acid anhydride include acetic anhydride, trimellitic anhydride, and pyromellitic anhydride. Among them, when acetic anhydride is used, purification after the end of the reaction becomes easy, so it is preferable. The rate of imidization through the catalyst imidization can be controlled by adjusting the amount of the catalyst, the reaction temperature, and the reaction time.

When the polyfluorene imide precursor or the polyfluorene imide reaction solution is recovered from the polyfluorene imide precursor or the polyfluorene imide, the reaction solution is put into a solvent to precipitate. Examples of the solvent used for the precipitation include methanol, ethanol, isopropanol, acetone, hexane, butyl cellosolve, heptane, methyl ethyl ketone, methyl isobutyl ketone, toluene, benzene, and water. After adding a solvent to the precipitated polymer for filtration and recovery, the polymer can be dried under normal pressure or reduced pressure, at normal temperature or under heating. In addition, when the polymer recovered by precipitation is re-dissolved in a solvent, and the operation of re-precipitation recovery is repeated 2 to 10 times, impurities in the polymer can be reduced. Examples of the solvent in this case include alcohols, ketones, and hydrocarbons. When three or more solvents selected from these solvents are used, the efficiency of purification can be further improved, which is preferable.

The weight average molecular weight (Mw) of the polyimide precursor and polyimide measured by gel permeation chromatography (GPC) in terms of polystyrene is preferably 1,000 to 500,000, and more preferably 2,000 to 300,000. . 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 15 or less, and more preferably 10 or less. By having such a molecular weight range, good alignment of the liquid crystal display element can be ensured.

<Liquid crystal alignment agent> The liquid crystal alignment agent of the present invention is a coating solution for forming a liquid crystal alignment film (also referred to as a resin film), and a coating solution for forming a liquid crystal alignment film containing a specific polymer and a solvent. As the specific polymer, a polyimide-based polymer selected from the group consisting of polyamidic acid, polyalkylamic acid alkyl ester, and polyimide can be used.所有 All polymers in the liquid crystal alignment agent of the present invention may be all specific polymers, or polymers other than these may be mixed. Examples of the polymers other than these include polyfluorenes which do not have a partial structure selected from the aforementioned formula [U], a structure represented by the aforementioned formulas [S1] to [S2], and a side chain structure having a structure having a steroid skeleton. Amine polymer. In addition, a cellulose polymer, an acrylic polymer, a methacryl fluorene-based polymer, polystyrene, polyamine, or polysiloxane can be exemplified. At this time, the content of other polymers other than these is preferably 5 to 90 parts by mass, and more preferably 10 to 60 parts by mass, relative to 100 parts by mass of the total polymer of the specific polymer and the other polymers.

The content of the solvent in the liquid crystal alignment agent of the present invention is preferably 70 to 99.9% by mass. This content can be suitably changed by the coating method of the liquid crystal alignment agent or the thickness of the liquid crystal alignment film of the purpose.时 The solvent used for the liquid crystal alignment agent of the present invention is not particularly limited when it is a solvent (also referred to as a good solvent) that dissolves the polymer. Specific examples of good solvents are listed below, but are not limited to these examples. Examples include N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-butyl-2- Pyrrolidone, dimethyl sulfene, γ-butyrolactone, γ-valerolactone, 1,3-dimethyl-2-imidazolidinone, 3-methoxy-N, N-dimethylpropanilamine , 3-butoxy-N, N-dimethylpropanamide, methyl ethyl ketone, cyclohexanone, cyclopentanone, 4-hydroxy-4-methyl-2-pentanone, and the like.

Among these, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-butyl-2-pyrrolidone, γ-butyrolactone, γ-valerolactone, and 1,3-dimethylformate are preferred. Methyl-2-imidazolinone, 3-methoxy-N, N-dimethylpropanamide, or 3-butoxy-N, N-dimethylpropanamide. In addition, when the polymer has a high solubility in a solvent, it is preferable to use a solvent represented by the aforementioned formula [D-1] to [D-3].良 The good solvent in the liquid crystal alignment agent of the present invention is preferably 5 to 99% by mass based on the total solvent contained in the liquid crystal alignment agent. Among these, 10 to 90% by mass is preferable.

As the liquid crystal alignment agent of the present invention, a solvent (also referred to as a weak solvent) which improves the coating property or surface smoothness of the liquid crystal alignment film when the liquid crystal alignment agent is applied can be used. Specific examples of the weak solvent are listed below, but are not limited to these examples. Examples include ethanol, isopropanol, 1-butanol, 2-butanol, isobutyl alcohol, tert-butanol, 1-pentanol, 2-pentanol, 3-pentanol, 2-methyl-1 -Butanol, isoamyl alcohol, tert-pentanol, 3-methyl-2-butanol, neopentyl alcohol, 1-hexanol, 2-methyl-1-pentanol, 2-methyl-2-pentanol Alcohol, 2-ethyl-1-butanol, 1-heptanol, 2-heptanol, 3-heptanol, 1-octanol, 2-octanol, 2-ethyl-1-hexanol, cyclohexanol , 1-methylcyclohexanol, 2-methylcyclohexanol, 3-methylcyclohexanol, 1,2-ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butane Diol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 2-methyl-2,4-pentanediol, 2- Ethyl-1,3-hexanediol, dipropyl ether, dibutyl ether, dihexyl ether, dioxane, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, 1,2 -Butoxyethane, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol methyl ether, diethylene glycol dibutyl ether, 2-pentanone, 3-pentanone, 2- Hexone, 2-heptanone, 4-heptanone, 3-ethoxybutyl acetate, 1-methylpentyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl ethyl Ester, Ethylene Alcohol monoacetate, ethylene glycol diacetate, propylene carbonate, ethylene carbonate, 2- (methoxymethoxy) ethanol, ethylene glycol monobutyl ether, ethylene glycol monoisoamyl ether, ethyl acetate Glycol monohexyl ether, 2- (hexyloxy) ethanol, furfuryl alcohol, diethylene glycol, propylene glycol, the solvent represented by the aforementioned formulas [D-1] to [D-3] or Diethyl ether, propylene glycol monopropyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, Diethylene glycol monobutyl ether, propylene glycol monobutyl ether, 1- (butoxyethoxy) propanol, propylene glycol monomethyl ether acetate, dipropylene glycol, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol Dimethyl ether, tripropylene glycol monomethyl ether, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, 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 acetic acid Ester, triethylene glycol, triethylene glycol monomethyl ether Triethylene glycol monoethyl ether, methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, n-butyl acetate, propylene glycol monoethyl ether acetate, methyl pyruvate, ethyl pyruvate, 3-methoxypropyl Methyl ester, methyl 3-ethoxypropionate, ethyl 3-methoxypropionate, 3-ethoxypropionic acid, 3-methoxypropionic acid, 3-methoxypropionic acid propionate Ester, 3-methoxypropionate, methyl lactate, ethyl lactate, n-propyl lactate, n-butyl lactate, isoamyl lactate, or 4-hydroxy-4-methyl-2-pentanone Wait.

Of these, 1-hexanol, cyclohexanol, 1,2-ethylene glycol, 1,2-propylene glycol, propylene glycol monobutyl ether, ethylene glycol monobutyl ether, or dipropylene glycol dimethyl ether, and diethylene glycol are preferred. Diethyl ether, 4-hydroxy-4-methyl-2-pentanone, propylene glycol diacetate, dipropylene glycol monomethyl ether, or propylene carbonate.弱 These solvents are preferably 1 to 95% by mass of the total solvent contained in the liquid crystal alignment agent. Among these, 10 to 90% by mass is preferable.

The liquid crystal alignment agent of the present invention may contain a crosslinkable compound having an epoxy group, an isocyanate group, an oxetanyl group, or a cyclic carbonate group, and a compound having a group selected from a hydroxyl group, a hydroxyalkyl group, and a lower alkoxyalkyl group. A crosslinkable compound having at least one substituent, or a crosslinkable compound having a polymerizable unsaturated bond. These substituents or polymerizable unsaturated bonds preferably have two or more in the crosslinkable compound. A crosslinkable compound having an epoxy group or an isocyanate group includes, for example, a compound described in paragraph [0087] of International Publication WO2015 / 008846. The crosslinkable compound having an oxetanyl group, specifically, a crosslinkable compound represented by the formulas [4a] to [4k] as disclosed in pages 58 to 59 of International Publication WO2011 / 132751. . More specific examples include compounds of formula [4b], formula [4d], and formula [4k], where n = 5.

The crosslinkable compound having a cyclic carbonate group may be specifically exemplified by crosslinks represented by the formulas [5-1] to [5-42] disclosed in pages 76 to 82 of International Publication WO2012 / 014898. Sexual compounds. The crosslinkable compound having at least one substituent selected from the group consisting of a hydroxyl group and an alkoxy group includes compounds described in paragraphs [0090] to [0092] of International Publication Gazette WO2015 / 008846.

Examples of the crosslinkable compound having a polymerizable unsaturated bond include the compounds described in paragraph [0186] of International Publication WO2011 / 132751. In addition, a compound represented by the formula [5] described in paragraph [0188] of International Publication WO2011 / 132751 can also be used. The above compound is an example of a crosslinkable compound, and is not limited to these. Moreover, the crosslinkable compound used for the liquid crystal aligning agent of this invention may be 1 type, and 2 or more types may be combined.含量 The content of the crosslinkable compound in the liquid crystal alignment agent of the present invention is preferably 0.1 to 150 parts by mass based on 100 parts by mass of all polymer components. Among them, when the crosslinking reaction proceeds and the intended effect is exhibited, it is preferably 0.1 to 100 parts by mass relative to 100 parts by mass of all the polymer components. More preferably, it is 1 to 50 parts by mass.

The liquid crystal alignment agent of the present invention can be a compound that improves the uniformity of the film thickness of the liquid crystal alignment film or the surface smoothness when the liquid crystal alignment agent is applied.化合物 Compounds that improve the uniformity of the thickness of the liquid crystal alignment film or the surface smoothness include fluorine-based surfactants, polysiloxane-based surfactants, and non-ionic surfactants. More specifically, for example, EFTOP EF301, EF303, EF352 (above, manufactured by TOHKEM PRODUCTS), Megafac F171, F173, R-30 (above, manufactured by Dainippon Ink), Fluorad FC430, FC431 (above, Sumitomo) 3M company), Asahiguard AG710, Surflon S-382, SC101, SC102, SC103, SC104, SC105, SC106 (above, manufactured by Asahi Glass Co., Ltd.), etc.

The use ratio of these surfactants is preferably 0.01 to 2 parts by mass, and more preferably 0.01 to 1 part by mass with respect to 100 parts by mass of all polymer components contained in the liquid crystal alignment agent. In addition, in the liquid crystal alignment agent of the present invention, a compound that promotes the charge movement in the liquid crystal alignment film and promotes the disappearance of the charge of the device may be added, for example, the formula disclosed in pages 69 to 73 of International Publication WO2011 / 132751 [M1] ~ A nitrogen-containing heterocyclic amine represented by the formula [M156]. This amine can be directly added to the liquid crystal alignment agent, but it is better to add it after forming a solution with a concentration of 0.1 to 10%, preferably 1 to 7% with an appropriate solvent. When this solvent is a solvent which melt | dissolves the said polyfluorene-imide-type polymer, it will not specifically limit.

In the liquid crystal alignment agent of the present invention, in addition to the above-mentioned weak solvent, crosslinkable compound, resin film or a compound that improves the uniformity or surface smoothness of the film thickness of the liquid crystal alignment film and a compound that promotes disappearance of the charge, the liquid crystal alignment can be added and changed Dielectric body or conductive substance for the purpose of the electrical characteristics such as the dielectric constant or conductivity of the film.

<Liquid crystal alignment film / liquid crystal display element> The liquid crystal alignment agent of the present invention is coated on a substrate, and after being fired, it is subjected to alignment treatment by rubbing treatment or light irradiation, etc., and can be used as a liquid crystal alignment film. In addition, for vertical alignment applications, etc., it can also be used as a liquid crystal alignment film without alignment treatment. The substrate used at this time is not particularly limited as long as it is a substrate having high transparency. In addition to a glass substrate, a plastic substrate such as an acrylic substrate or a polycarbonate substrate may be used. From the viewpoint of simplification of the steps, it is preferable to use a substrate formed with an ITO electrode or the like for liquid crystal driving. Moreover, in the case of a reflective liquid crystal display element, when only one substrate is used, an opaque substrate such as a silicon wafer may be used. In this case, an electrode that reflects light may be used.

The coating method of the liquid crystal alignment agent is not particularly limited. In industry, coating methods such as screen printing, lithography, letterpress printing, and inkjet are generally used. Other coating methods include a dipping method, a roll coating method, a slit coating method, a spin coater method, or a spray method, and these methods can be used depending on the purpose.

After the liquid crystal alignment agent is coated on the substrate, the heating means such as a heating plate, a thermal cycle type oven, or an IR (infrared) type oven is used, and the solvent used for the liquid crystal alignment agent is 30 to 300 ° C, preferably A temperature of 30 to 250 ° C causes the solvent to evaporate to form a liquid crystal alignment film. The thickness of the liquid crystal alignment film after firing is too thick, which is disadvantageous in terms of power consumption of the liquid crystal display element. When it is too thin, the reliability of the liquid crystal display element may be reduced, so it is preferably 5 to 300 nm, and more preferably 10 ~ 100nm. When the liquid crystal is aligned horizontally or obliquely, the fired liquid crystal alignment film is treated with rubbing or polarized ultraviolet rays.液晶 The liquid crystal display element of the present invention uses the above-mentioned method to obtain a substrate with a liquid crystal alignment film from the liquid crystal alignment agent of the present invention, and then uses a conventional method to prepare a liquid crystal cell as a liquid crystal display element.

The manufacturing method of the liquid crystal cell is, for example, preparing a pair of substrates having a liquid crystal alignment film, and a spacer is sprayed on the liquid crystal alignment film of one of the substrates, so that the liquid crystal alignment film surface becomes the inner side, and the other substrate is bonded. A method of injecting liquid crystal and encapsulating it, or a method of dropping a liquid crystal onto a liquid crystal alignment film surface interspersed with a spacer, and then attaching a substrate for encapsulation. In addition, the liquid crystal alignment agent of the present invention is suitable for use in a liquid crystal display element manufactured through the following steps. This step includes a liquid crystal layer between a pair of substrates provided with electrodes. A step of applying a voltage between electrodes to a liquid crystal composition of a polymerizable compound polymerized by at least one of active energy ray and heat to polymerize the polymerizable compound by at least one of irradiation and heating of active energy ray. The active energy ray is preferably ultraviolet rays. The ultraviolet-based wavelength is 300 to 400 nm, and preferably 310 to 360 nm. In the case of polymerization by heating, the heating temperature is 40 to 120 ° C, preferably 60 to 80 ° C. In addition, ultraviolet rays and heating may be performed simultaneously.

The above liquid crystal display device controls a pretilt of liquid crystal molecules by a PSA (Polymer Sustained Alignment) method. The PSA method involves mixing a small amount of a photopolymerizable compound into a liquid crystal material, for example, a photopolymerizable monomer. After assembling a liquid crystal cell, the photopolymerizable compound is irradiated with ultraviolet rays and the like while a specific voltage is applied to the liquid crystal layer. The polymer controls the pretilt of liquid crystal molecules. The alignment state of the liquid crystal molecules at the time of polymer generation is memorized even after the voltage is removed. Therefore, the pretilt of the liquid crystal molecules can be adjusted by controlling the electric field formed by the liquid crystal layer. In addition, the PSA method does not require rubbing treatment, so it is suitable for forming a vertical alignment type liquid crystal layer that is difficult to control pretilt by rubbing treatment.

That is, the liquid crystal display element of the present invention is obtained by the above-mentioned method. After the substrate with a liquid crystal alignment film is obtained from the liquid crystal alignment agent of the present invention, a liquid crystal cell is produced, and the polymerizable compound is polymerized by at least one of irradiation and heating of ultraviolet rays. , Can control the alignment of liquid crystal molecules. As an example of the production of a liquid crystal cell by the PSA method, a pair of substrates prepared with a liquid crystal alignment layer can be listed, and a gap is spread on the liquid crystal alignment film of one of the substrates so that the liquid crystal alignment film surface becomes the inner side and is bonded to the other A method of injecting liquid crystal into a substrate under reduced pressure, and encapsulating it, or a method of dropping the liquid crystal onto a liquid crystal alignment film surface interspersed with a spacer, and then attaching the substrate for encapsulation.

The liquid crystal is mixed with a polymerizable compound that is polymerized by heat or ultraviolet radiation. Examples of the polymerizable compound include compounds having one polymerizable unsaturated group such as an acrylate group or a methacrylate group in the molecule. At this time, the polymerizable compound is preferably 0.01 to 10 parts by mass, and more preferably 0.1 to 5 parts by mass, with respect to 100 parts by mass of the liquid crystal component. When the polymerizable compound is less than 0.01 parts by mass, the polymerizable compound does not polymerize and it becomes impossible to control the alignment of the liquid crystal, and when it exceeds 10 parts by mass, the amount of unreacted polymerizable compound increases and the afterimage characteristics of the liquid crystal display element decrease. . After making the liquid crystal cell, apply an AC or DC voltage to the liquid crystal cell, and simultaneously irradiate heat or ultraviolet rays to polymerize the polymerizable compound. Thereby, the alignment of the liquid crystal molecules can be controlled.

In addition, the liquid crystal alignment agent of the present invention is suitable for use in a liquid crystal display element manufactured through the following steps. This step includes a liquid crystal layer between a pair of substrates provided with electrodes. The step of applying a voltage between the electrodes of the polymerizable liquid crystal alignment film polymerized by at least one of active energy rays and heat, that is, SC-PVA mode. The active energy ray is preferably ultraviolet rays. The ultraviolet-based wavelength is 300 to 400 nm, and preferably 310 to 360 nm. In the case of polymerization by heating, the heating temperature is 40 to 120 ° C, preferably 60 to 80 ° C. In addition, ultraviolet rays and heating may be performed simultaneously.

In order to obtain a liquid crystal alignment film containing a polymerizable group polymerized by at least one of active energy rays and heat, a method of adding a compound containing the polymerizable group to a liquid crystal alignment agent or using a polymerizable group Based polymer composition method. Specific examples of the polymer containing a polymerizable group are not particularly limited as long as it is a polymer having the photoreactive group, and a polymer obtained by using a diamine having the photoreactive group is mentioned. For example, in the production of a liquid crystal cell in the SC-PVA mode, can list a pair of substrates prepared to form the liquid crystal alignment film of the present invention, and the liquid crystal alignment film of one of the substrates is interspersed with a gap so that the liquid crystal alignment film surface becomes the inside , A method of bonding another substrate, injecting liquid crystal under reduced pressure, and packaging, or a method of bonding the substrate and packaging after dropping the liquid crystal to a liquid crystal alignment film surface interspersed with a spacer. (2) After the liquid crystal cell is manufactured, while applying AC or DC voltage to the liquid crystal cell, while irradiating heat or ultraviolet rays, the alignment of the liquid crystal molecules can be controlled.

As described above, the liquid crystal alignment agent of the present invention can obtain a liquid crystal alignment film that can exhibit a stable pretilt angle even after being exposed to high temperature and light irradiation for a long time. In addition, even after being exposed to light for a long time, it can be a liquid crystal alignment film that suppresses a decrease in the voltage holding ratio and relaxes the residual charge accumulated by the DC voltage. Therefore, a liquid crystal display element having a liquid crystal alignment film obtained from the liquid crystal alignment agent of the present invention is one having excellent reliability, and is suitable for large-screen and high-definition liquid crystal televisions, small and medium-sized car navigation systems, and smart phones.

[Example]

Examples are given below to explain the present invention more specifically, but the present invention is not limited to these. The abbreviations and evaluation methods of the compounds used below are as follows. (Diamine component)

C1: 1,3-diamino-4- [4- (trans-4-n-heptylcyclohexyl) phenoxy] benzene C2: 1,3-diamino-4- [4- (trans Formula 4-n-heptylcyclohexyl) phenoxymethyl] benzene C3: 1,3-diamino-4- {4- [trans-4- (trans-4-n-pentyl ring Hexyl) cyclohexyl] phenoxy} benzene C4: a diamine C5 represented by the following formula [C4]: 1,3-diamino-4-octadecyloxybenzene

(Tetracarboxylic acid component)

(Crosslinkable compound) (Solvent) NMP: N-methyl-2-pyrrolidone, NEP: N-ethyl-2-pyrrolidone γ-BL: γ-butyrolactone γ-VL: γ-valerolactone CHN: cyclohexanone BCS: ethyl Glycol monobutyl ether PB: propylene glycol monobutyl ether EC: diethylene glycol monoethyl ether DME: dipropylene glycol dimethyl ether: PC: propylene carbonate DAA: 4-hydroxy-4-methyl-2-pentanone PGDA: propylene glycol Diacetate:

(Measurement of molecular weight) The molecular weights of the polyimide precursor and polyimide were measured using a normal temperature gel permeation chromatography (GPC) device (GPC-101) (manufactured by Showa Denko Corporation), and a column (KD-803, KD-805) (manufactured by Shodex) and measured as follows. Column temperature: 50 ℃ Eluent: N, N'-dimethylformamide (additive is lithium bromide-hydrate (LiBr ･ H ₂ O) 30mmol / L (liter), anhydrous crystal of phosphoric acid (o-phosphoric acid) ) Is 30mmol / L, tetrahydrofuran (THF) is 10ml / L) Flow rate: 1.0ml / min Calibration curve preparation standard sample: TSK standard polyethylene oxide (molecular weight; about 900,000, 150,000, 100,000 and 30,000) (East Manufactured by Tsao Corporation) and polyethylene glycol (molecular weight; approximately 12,000, 4,000, and 1,000) (manufactured by Polymer Laboratories).

(Measurement of Polyimide Imidization Rate) Put 20 mg of polyimide powder into an NMR sampling tube stand (NMR sampling tube stand, φ5 (manufactured by Kusano Science)), and add deuterated dimethyl Glycoarene (DMSO-d6, 0.05% TMS (tetramethylsilane) mixed product) (0.53 ml), applied ultrasonic to completely dissolve. This solution was used to measure a proton NMR at 500 MHz using an NMR measuring machine (JNW-ECA500) (manufactured by Japan Electronics Datum Corporation). The hydrazone imidization rate is based on the protons from structures that have not changed before and after hydrazone imidization. The protons from this structure are used as the cumulative proton value, and the NH group from hydrazone is present at around 9.5 to 10.0 ppm. The cumulative value of the proton peaks is calculated by the following formula.醯 Imination ratio (%) = (1-α ･ x / y) × 100 In the above formula, x is the cumulative value of the proton peak derived from the NH group of the amino acid, y is the cumulative value of the peak of the standard proton, and α is the In the case of polyamidic acid (the imidization ratio of fluorene is 0%), the ratio of the number of reference protons to one NH matrix proton of fluoramic acid.

(Synthesis of polyfluorene imine-based polymer) <Synthesis Example 1> NMP was added to a mixture of E2 (7.10 g, 28.5 mmol), A1 (5.00 g, 9.00 mmol), and C1 (8.00 g, 21.0 mmol). The resin solid content concentration was 25%, and the reaction was performed at 50 ° C for 6 hours. Next, it diluted with NMP so that resin solid content concentration might be 10%, and obtained the polyamic-acid solution (1). The polyamic acid had Mn of 10,200 and Mw of 24,500.

<Synthesis Example 2> MPIn a mixture of E1 (5.60 g, 28.5 mmol), A1 (5.00 g, 9.00 mmol), and C3 (9.10 g, 21.0 mmol), NMP was added to make the solid content concentration of the resin 25%, so that The reaction was carried out at 6 ° C for 6 hours. Next, it was diluted with NMP so that the resin solid content concentration became 10% to obtain a polyamic acid solution (2). The polyamic acid had an Mn of 14,000 and an Mw of 30,500.

<Synthesis Example 3> In the polyamino acid solution (1) (30.0 g) obtained in Synthesis Example 1, NEP was added to dilute to 6%, and then acetic anhydride (3.42 g) and pyridine as the phosphonium imidization catalyst were added. (2.65 g) and reacted at 60 ° C for 2 hours. This reaction solution was poured into methanol (1946 ml), and the obtained precipitate was obtained by filtration. This precipitate was washed with methanol and dried under reduced pressure at 100 ° C to obtain a polyfluorene imine powder (3). The polyimide has a fluorene imidation ratio of 50%, Mn of 11,500, and Mw of 31,300.

<Synthesis Example 4> A polyimide powder (4) was obtained in the same manner as in Synthesis Example 3, except that the composition shown in Table 1 was used. <Synthesis Example 5> (1) E1 (5.60 g, 28.5 mmol), A2 (4.84 g, 14.3 mmol), D1 (0.62 g, 5.70 mmol), and D2 (1.30 g, 8.55 mmol) were added, and then NMP was added to increase the resin solid content concentration. Become 10%. After reacting at 25 ° C for 4 hours, a polyamic acid solution (5) was obtained. This polyamic acid had Mn of 11,000 and Mw of 25,100.

<Comparative Synthesis Example 1> NMP was added to a mixture of E2 (9.50 g, 38.0 mmol), D3 (2.60 g, 12.0 mmol) and C1 (10.7 g, 28.0 mmol) to increase the resin solid content concentration to 25%. The reaction was carried out at 50 ° C for 6 hours. Next, it was diluted with NMP so that the resin solid content concentration became 10%, and a polyamidic acid solution (R-1) was obtained. This polyamic acid had Mn of 12,000 and Mw of 28,500.

The polyfluorene-imide polymer obtained in the said synthesis example is shown in Table 1. In Tables 1 and 4, * 1 indicates polyamidic acid.

<Reference Example 1> (1) (0.73 g) was added to a polyamic acid solution (1) (0.73 g) having a resin solid content concentration of 10% obtained by the synthesis method of Synthesis Example 1, and stirred at 25 ° C. No abnormality such as turbidity or precipitation was observed in this liquid crystal alignment agent, and it was confirmed to be a uniform solution.

<Comparative Reference Example 1> Into a polyamic acid solution (R-1) (0.73g) having a resin solid content concentration of 10% obtained by the synthetic method of Comparative Synthesis Example 1, pure water (0.90g) was added, and the temperature was 25 ° C. Stir. This liquid crystal alignment agent was observed to precipitate, and it was not confirmed as a uniform solution.

(Production of liquid crystal alignment agent) 例 In Examples 1 to 4 and Comparative Example 1 described below, production examples of the liquid crystal alignment agent are described. This liquid crystal alignment agent was also used for evaluation.

<Example 1> Into the polyamic acid solution (1) (3.50 g) obtained in Synthesis Example 1, NEP (0.55 g), GBL (0.55 g), and PB (1.40 g) were added, and stirred at 25 ° C for 6 hours. To obtain a liquid crystal alignment agent (1). No abnormality such as turbidity or precipitation was observed in this liquid crystal alignment agent, and it was confirmed to be a uniform solution. <Example 2> NMP (0.05g), BCS (1.05g), and DME (1.05g) were added to the polyamic acid solution (2) (3.50g) obtained in Synthesis Example 2, and stirred at 25 ° C for 6 hours. To obtain a liquid crystal alignment agent (2). No abnormality such as turbidity or precipitation was observed in this liquid crystal alignment agent, and it was confirmed to be a uniform solution.

<Example 3> To the polyfluorene imine powder (3) (1.75 g) obtained in Synthesis Example 3, CHN (22.5 g), γ-VL (11.6 g), and PGME (22.5 g) were added and stirred at 50 ° C. 6 hours. K1 (0.17 g) was further added, and it stirred at 25 degreeC for 4 hours, and obtained the liquid crystal aligning agent (3). No abnormality such as turbidity or precipitation was observed in this liquid crystal alignment agent, and it was confirmed to be a uniform solution.

<Example 4> NMP (2.70 g) was added to the polyfluorene imine powder (4) (0.30 g) obtained in Synthesis Example 4, and stirred at 50 ° C. for 6 hours. Then, 7.00 g of the polyamic acid solution (5) obtained in Synthesis Example 5 was added, and PC (6.58 g), NEP (6.50 g), and NMP (10.25 g) were added, and the mixture was stirred at 25 ° C for 4 hours to obtain a liquid crystal alignment agent (4 ). No abnormality such as turbidity or precipitation was observed in this liquid crystal alignment agent, and it was confirmed to be a uniform solution.

<Comparative Example 1> As shown in Table 2, except that the polyamic acid solution (R-1) obtained in Comparative Synthesis Example 1 was used, a liquid crystal alignment agent (R1) was obtained in the same manner as in Example 1. No abnormality such as turbidity or precipitation was observed in this liquid crystal alignment agent, and it was confirmed to be a uniform solution.

In Tables 2 and 5, * 1, * 2, and * 3 have the following meanings. * 1: It means the mass part of the crosslinkable compound with respect to 100 mass parts of all polymers. * 2: Mass parts of each solvent with respect to 100 mass parts of all solvents. * 3: Represents the ratio of all polymers in the liquid crystal alignment agent.

(Evaluation of liquid crystal alignment agent) For the results obtained in Examples and Comparative Examples, the following "evaluation of whitening resistance", "evaluation of inkjet coating properties", "production of liquid crystal cells and evaluation of liquid crystal alignment properties (usually Cell ) ", And" production of liquid crystal cells and evaluation of liquid crystal alignment (PSA Cell) ".

"Evaluation of whitening resistance" One drop of a liquid crystal alignment agent was dropped on a Cr substrate having a length of 10 cm and a square, and the time until the liquid crystal alignment agent was whitened was measured under the conditions of a temperature of 40 ° C and a humidity of 65%. The time is less than 30 minutes and is evaluated as C, the time 30 minutes or more and less than 2 hours is evaluated as A, and the time is more than 2 hours as S. The longer the time, the better. The results are shown in Table 3.

(Evaluation of inkjet coating properties) (1) The liquid crystal alignment agents (1) to (4) were subjected to pressure filtration using a thin-film filter having a pore size of 1 μm to evaluate the inkjet coating properties. As the inkjet coater, HIS-200 (manufactured by Hitachi Plant Technologies) was used. Coating is performed on an ITO (indium tin oxide) evaporation substrate washed with pure water and isopropyl alcohol (IPA), with a nozzle pitch of 0.423 mm, a scanning pitch of 0.5 mm, a coating speed of 40 mm / sec, and self-coating The time until the cloth was temporarily dried was 60 seconds, and the temporary drying was performed on a hot plate at 70 ° C. for 5 minutes. Confirm the coating property of the obtained substrate with a liquid crystal alignment film. Specifically, the coating film was visually observed under a sodium lamp, and the presence or absence of pinholes was confirmed. As a result, no pinhole was observed in the coating film of the liquid crystal alignment film obtained in each Example, and a liquid crystal alignment film having excellent coating film properties was obtained.

(Production of liquid crystal cells and evaluation of liquid crystal alignment (usually Cell)) The liquid crystal alignment agent (1) or (3) obtained in the examples was subjected to pressure filtration using a membrane filter with a pore size of 1 μm to produce liquid crystal cells ( Usually Cell). Next, the above-mentioned liquid crystal alignment agent was spin-coated on an ITO surface with an ITO electrode substrate (length 40 mm × width 30 mm, thickness 0.7 mm) of 40 × 30 mm washed with pure water and IPA. A heat treatment was performed for 5 minutes, and a heat cycle type cleaning oven was used at 230 ° C. for 30 minutes to obtain an ITO substrate with a liquid crystal alignment film having a film thickness of 100 nm. In addition, the liquid crystal alignment agent (2) or (4) obtained in the examples was prepared under the same conditions as the above-mentioned "evaluation of the inkjet coating property of the liquid crystal alignment agent" with a substrate with a liquid crystal alignment film, and then subjected to thermal cycling. The cleaning oven was heated at 230 ° C. for 30 minutes to obtain an ITO substrate with agglomerated polyimide liquid crystal alignment film having a film thickness of 100 nm. Next, the coating surface of the ITO substrate was subjected to a rubbing treatment using a friction device having a roll diameter of 120 mm, using a rayon cloth, and a roll rotation speed of 1,000 rpm, a roll speed of 50 mm / sec, and a pushing amount of 0.1 mm.

Two pieces of the prepared ITO substrate with a liquid crystal alignment film were prepared, the liquid crystal alignment film surface was inside, and a gap having a pore diameter of 6 μm was clamped to form a combination, and a sealant was used to surround the periphery to produce an empty cell. Liquid crystal (MLC-6608, manufactured by Merck Japan Corporation) is injected into the empty cell by a reduced pressure injection method, and the injection port is closed to obtain a liquid crystal cell (usually Cell). Each of the liquid crystal cells was observed with a polarizing microscope (ECLIPSE E600WPOL) (manufactured by NIKON), and it was confirmed that the liquid crystals were uniformly aligned.

(Production of Liquid Crystal Cells and Evaluation of Liquid Crystal Orientation (PSACell)) In addition to using 100 parts by mass of the polymerizable compound (1) represented by the following formula with respect to 100 parts by mass of nematic liquid crystal (MLC-6608), With the exception of 0.3 parts by mass of the liquid crystal of the polymerizable compound (1), a liquid crystal cell was prepared in the same procedure as in the above-mentioned "production of liquid crystal cell and evaluation of pretilt angle (normal cell)".

A voltage of 5V AC was applied to the obtained liquid crystal cell, and a metal halide lamp with an illuminance of 60mW was used to block a wavelength below 350nm and irradiate ultraviolet rays converted at 365nm to 20J / cm ^{2 to} obtain a liquid crystal cell with controlled orientation direction of the liquid crystal (PSACell ). The temperature in the irradiation device when the liquid crystal cell was irradiated with ultraviolet rays was 50 ° C. Each of the liquid crystal cells was observed with a polarizing microscope (ECLIPSE E600WPOL) (manufactured by NIKON), and it was confirmed that the liquid crystals were uniformly aligned.

From the above reference examples, the polymer of the present invention exhibits higher solubility when water is mixed in than the polymer obtained from the comparative synthesis example. The liquid crystal alignment agent shown in Table 3 exhibited higher whitening resistance than the liquid crystal alignment agent of the comparative example. Further, from the above-mentioned "Evaluation of Inkjet Coating Property of Liquid Crystal Alignment Agent", "Evaluation of Liquid Crystal Alignment Property (Normal Cell)", and "Evaluation of Liquid Crystal Alignment Property (PSA Cell)", it was found that various characteristics were excellent.

<Synthesis Examples 6 to 7> A polyamic acid solution (6) and a polyimide powder (7) were obtained in the same manner as in Synthesis Examples 1 to 5, except that the compositions shown in Table 4 were used.

<Example 5> As shown in Table 5, a liquid crystal alignment was obtained in the same manner as in Example 4 except that the polyamidic acid solution (6) obtained in Synthesis Example 6 or the polyamidoimide powder (7) obtained in Synthesis Example 7 was used.剂 (5). No abnormality such as turbidity or precipitation was observed in this liquid crystal alignment agent, and it was confirmed to be a uniform solution. The aforementioned PSACell is produced using a liquid crystal alignment agent (5), and the liquid crystal is uniformly aligned. [Industrial availability]

The liquid crystal alignment agent of the present invention is suitable for, for example, a large-screen and high-definition liquid crystal television or a small and medium-sized car navigation system or a smart phone. Display element. In addition, the liquid crystal alignment film obtained from the liquid crystal alignment agent of the present invention can also be used for a liquid crystal display element that must be irradiated with ultraviolet rays when producing a liquid crystal display element.

In addition, the entire contents of the specification, scope of patent application, drawings, and abstract of Japanese Patent Application No. 2017-101174 filed on May 22, 2017 are incorporated herein as disclosure of the specification of the present invention and are incorporated herein by reference. .

Claims (17)

A liquid crystal alignment agent comprising: a side chain structure selected from the group consisting of a partial structure represented by the following formula [U] and a group consisting of the following formula [S1], [S2], and a steroid skeleton; A polymer of at least one of the group consisting of a polyimide precursor and a polyimide of a polyimide of the polyimide precursor, (Y ¹ and Y ² are each independently a single bond, -O-, -S-, -COO-, or -OCO-, and K ¹ and K ² are each independently -CH ₂ -group, -CHR ^1a -group (R ^1a Represents an -OH group or a monovalent organic group). Here, any one of K ¹ and K ² may be substituted by a -C (O) group, and R ³ and R ⁴ are each independently an extension of 1 to 7 carbon atoms. Alkyl, * indicates any of the sites bonded to other radicals), (X ¹ and X ^{2 are} independently a single bond,-(CH ₂ ) _a- (a is 1 ~ 15), -CONH-, -NHCO-, -CON (CH ₃ )-, -NH-, -O-, -COO-, -OCO- or-((CH ₂ ) _a1 -A ₁ ) _m1- (a1 is 1 ~ 15, A ₁ is an oxygen atom or COO-, m ₁ is 1 ~ 2), G ¹ and G ² Each is independently a divalent aromatic group having 6 to 12 carbon atoms or a divalent cyclic group selected from a divalent alicyclic group having 3 to 8 carbon atoms. Any hydrogen atom on the cyclic group can be replaced by a carbon number. 1 to 3 alkyl, 1 to 3 carbon alkoxy, 1 to 3 carbon fluorinated alkyl, 1 to 3 carbon fluorinated alkoxy or fluorine atom substitution, m and n are independently 0 ~ 3, the total of these is 1 ~ 4, R ¹ is an alkyl group having 1 to 20 carbons, an alkoxy group having 1 to 20 carbons or an alkoxyalkyl group having 2 to 20 carbons, among these groups (Any hydrogen atom can be replaced by a fluorine atom) (X ³ is a single bond, -CONH-, -NHCO-, -CON (CH ₃ )-, -NH-, -O-, -CH ₂ O-, -COO- or OCO-, and R ² is a carbon number of 1 An alkyl group of ~ 20 or an alkoxyalkyl group of 2 to 20 carbons, and any hydrogen atom in these groups may be substituted by a fluorine atom). For example, the liquid crystal alignment agent of claim 1, wherein a part of the structure represented by the aforementioned formula [U] is the following formula [U-Ar], (Y ¹ , Y ² , K ¹ , K ² , R ³ and R ⁴ are the same as defined in the aforementioned formula (U)). For example, the liquid crystal alignment agent of claim 1 or 2, wherein the foregoing polyfluorene imide precursor is obtained by using a diamine represented by the following formula [U-1] as part of a raw material, (Y ^A is an organic group having a structure represented by the aforementioned formula [U], and A ¹ and A ² are each independently a hydrogen atom or an alkylene group having 1 to 5 carbon atoms). For example, the liquid crystal alignment agent of claim 3, wherein the aforementioned diamine is a diamine represented by the following formula [Ua], (Y ¹ , Y ² , K ¹ , K ² , R ³ and R ⁴ are the same as defined in the aforementioned formula (U), and A ¹ and A ² are the same as defined in the aforementioned formula [U-1]). For example, the liquid crystal alignment agent of claim 3 or 4, wherein the diamine is at least one diamine selected from the group consisting of diamines represented by the following formulas [U-1a] to [U-6a], (A ¹ and A ² are the same as defined in the aforementioned formula (U), and Boc is a third butoxycarbonyl group). The liquid crystal alignment agent according to any one of claims 1 to 5, wherein the aforementioned polyfluorene imide precursor is a part of a raw material using a diamine represented by the following formula [S1-a], (B is the aforementioned formula [S1], [S2] or the following formula [3], A ¹ and A ² are each independently a hydrogen atom or an alkylene group having 1 to 5 carbon atoms, and m is 1 to 4) (X ⁴ is -CONH-, -NHCO-, -O-, -COO-, or OCO-, and R ³ is a structure having a steroid skeleton). The liquid crystal alignment agent according to any one of claims 1 to 6, wherein the polyimide precursor is a polyimide precursor obtained by using a tetracarboxylic acid component containing a tetracarboxylic anhydride represented by the following formula [4] , (Z represents at least one structure selected from the group consisting of the following formulas [4a] to [4k]) (In the formula [4a], Z ¹ to Z ⁴ are each independently a hydrogen atom, a methyl group, an ethyl group, a propyl group, a chlorine atom or a benzene ring, and in the formula [4 g], Z ⁵ and Z ⁶ are each independently a hydrogen atom or methyl). For example, the liquid crystal alignment agent of claim 7, wherein the aforementioned tetracarboxylic acid anhydride has Z in the aforementioned formula [4] and is at least 1 selected from the group consisting of the aforementioned formulas [4a] and [4e] to [4g]. Structure of tetracarboxylic anhydride. The liquid crystal alignment agent according to any one of claims 4 to 8, wherein the aforementioned polyfluorene imide precursor is used in 100 mol% of a total diamine component for obtaining the polyfluorene imide precursor, the aforementioned formula [ The diamine represented by Ua] contains 1 to 99 mole%, the diamine represented by the aforementioned formula [S1-a] contains 1 to 99 mole%, and their total amount is 5 to 100 mole% of diamine. The obtained polyimide precursor. The liquid crystal alignment agent according to any one of claims 4 to 9, wherein the aforementioned polyfluorene imide precursor is used in 100 mol% of the total diamine component, and the diamine represented by the aforementioned formula [Ua] contains 5 mol. Polyimide precursors obtained from diamines of more than% and polyamines obtained from 100 mol% of total diamines. The polyamines obtained from the above formula [S1-a] contain 1 mol% or more of diamines. A mixture of amidine precursors. The liquid crystal alignment agent according to any one of claims 1 to 10, which contains a liquid crystal alignment agent selected from the group consisting of N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-butyl-2-pyrrolidone, and γ-butane. Lactone, γ-valerolactone, 1,3-dimethyl-2-imidazolinone, 3-methoxy-N, N-dimethylpropanamide, and 3-butoxy-N, N -At least one solvent of the group consisting of dimethylpropanamine. The liquid crystal alignment agent according to any one of claims 1 to 11, further comprising a liquid crystal alignment agent selected from the group consisting of 1-hexanol, cyclohexanol, 1,2-ethylene glycol, 1,2-propylene glycol, propylene glycol monobutyl ether, and ethyl alcohol. Glycol monobutyl ether and dipropylene glycol dimethyl ether, diethylene glycol diethyl ether, 4-hydroxy-4-methyl-2-pentanone, propylene glycol diacetate, dipropylene glycol monomethyl ether, and propylene carbonate At least one solvent of the group. The liquid crystal alignment agent according to any one of claims 1 to 12, which contains: a crosslinkable compound having an epoxy group, an isocyanate group, an oxetanyl group, or a cyclic carbonate group, having a member selected from the group consisting of a hydroxyl group, a hydroxyl group A crosslinkable compound having at least one kind of substituent group of an alkyl group or a lower alkoxyalkyl group, and at least one kind selected from the group consisting of a crosslinkable compound having a polymerizable unsaturated bond Crosslinkable compound. A liquid crystal alignment film is obtained from the liquid crystal alignment agent according to any one of claims 1 to 13. For example, the liquid crystal alignment film of claim 14 is for a liquid crystal display element manufactured through the following steps. The step is formed between a pair of substrates provided with electrodes and a liquid crystal layer. And a step of polymerizing the polymerizable compound while applying a voltage between the electrodes by applying a liquid crystal composition of the polymerizable compound polymerized by at least one of active energy rays and heat. The liquid crystal alignment film according to claim 15, wherein the liquid crystal alignment film is a liquid crystal alignment film containing a compound having a polymerizable group that is polymerized by at least one of active energy rays and heat. A liquid crystal display element having a liquid crystal alignment film according to any one of claims 14 to 16.