TW202411409A - Liquid crystal alignment agent, liquid crystal alignment film and liquid crystal display element capable of obtaining a liquid crystal alignment film having high mechanical strength - Google Patents

Abstract

The present invention provides a liquid crystal alignment agent capable of obtaining a liquid crystal alignment film having high mechanical strength even when using substituted cyclobutane tetracarboxylic dianhydride or its derivatives as raw materials to obtain a polyimide liquid crystal alignment film, and provides the liquid crystal alignment film and the liquid crystal display element using the liquid crystal alignment film. A liquid crystal alignment agent is characterized by containing a polymer (A). The polymer (A) is at least one selected from a group consisting of a polyimide precursor having a repeating unit (a1) represented by formula (1) and a polyimide that is an imide product of the polyimide precursor. R and Z each independently represent a hydrogen atom or a monovalent organic group.

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 and a liquid crystal display element.

Liquid crystal display devices are widely used as display parts of personal computers, smart phones, mobile phones, televisions, etc. Liquid crystal display devices usually have: a liquid crystal layer sandwiched between a display element substrate and a color filter substrate, a pixel electrode and a common electrode for applying an electric field to the liquid crystal layer, an alignment film for controlling the alignment of liquid crystal molecules in the liquid crystal layer, and a thin film transistor (TFT) for switching the electrical signal supplied to the pixel electrode. The known driving methods of liquid crystal molecules include: longitudinal electric field methods such as TN method and VA method, lateral electric field methods such as IPS (In Plane Switching) driving method and FFS (Fringe Field Switching) driving method.

The most popular liquid crystal alignment film in industry is produced by rubbing the surface of a film composed of polyamide and/or polyimide obtained by imidization formed on an electrode substrate with a cloth such as cotton, nylon, polyester, etc. in one direction. The rubbing treatment is a simple and productive method that is useful in industry. However, with the high performance, high precision, and large-scale development of liquid crystal display elements, various problems such as scratches, dust, mechanical force, and static electricity on the surface of the alignment film produced by the rubbing treatment have become apparent, as well as the unevenness within the alignment treatment surface. As an alignment treatment method that replaces the rubbing treatment, a photoalignment method is known that imparts alignment ability to liquid crystals by irradiating polarized radiation. Regarding the photoalignment method, some have proposed methods using photoisomerization reaction, methods using photocrosslinking reaction, methods using photodecomposition reaction, etc. (for example, refer to non-patent document 1, patent documents 1, 2). In recent years, small display terminals such as high-precision tablet PCs and car navigation have become the mainstay, and the requirements for high-quality liquid crystal display elements are higher than ever before. In particular, for reliability testing of liquid crystal display elements for automotive applications such as car navigation, vibration tests of the panels are sometimes performed. This vibration test requires that no defects such as bright spots occur. In order to obtain a liquid crystal display element that does not produce defects after the vibration test, some people have considered methods such as improving the mechanical strength of the liquid crystal alignment film. [Prior technical literature] [Patent literature]

[Patent Document 1] Japanese Patent Publication No. 9-297313 [Patent Document 2] Japanese Patent Publication No. 2004-206091 [Non-patent Document]

[Non-patent document 1] "Functional Materials", November 1997, Vol.17, No.11, pp.13-22

(The problem to be solved by the invention)

After reviewing, the inventors of the present case realized that the conventional polyimide liquid crystal alignment film obtained by using substituted cyclobutanetetracarboxylic dianhydride or its derivatives as raw materials may not be able to meet the high-level requirements if the requirements for higher mechanical strength properties are taken into consideration in the future.

The present invention is made in view of the above circumstances, and aims to provide a liquid crystal alignment agent, a liquid crystal alignment film, and a liquid crystal display element using the liquid crystal alignment film, which can obtain a liquid crystal alignment film having high mechanical strength even when the polyimide liquid crystal alignment film is obtained using substituted cyclobutanetetracarboxylic dianhydride or its derivatives as raw materials. (Method for solving the problem)

The inventor of this case has made great efforts in research and found that the above-mentioned problems can be solved by using a liquid crystal alignment agent containing specific components, thus completing the present invention.

The present invention specifically has the following aspects.

A liquid crystal alignment agent is characterized by containing a polymer (A), wherein the polymer (A) is at least one selected from the group consisting of a polyimide precursor having a repeating unit (a1) represented by the following formula (1) and a polyimide which is an imide compound of the polyimide precursor.

[Chemistry 1]

R and Z each independently represent a hydrogen atom or a monovalent organic group. In addition, throughout this specification, the following terms and abbreviations have the following meanings. Halogen atoms are fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, etc. * All represent atomic bonds. In addition, Boc represents tert-butyloxycarbonyl, and Fmoc represents 9-fluorenylmethoxycarbonyl. (Effect of the invention)

According to the present invention, a liquid crystal alignment agent can be provided which can obtain a liquid crystal alignment film having high mechanical strength even when a polyimide liquid crystal alignment film is obtained using substituted cyclobutanetetracarboxylic dianhydride or a derivative thereof as a raw material, the liquid crystal alignment film, and a liquid crystal display element using the liquid crystal alignment film.

The mechanism by which the present invention achieves the above effects is not necessarily clear, but the following is considered to be one of the reasons: It is considered that the fewer the substituents, the smaller the steric hindrance, which does not hinder the interaction between molecules, and thus the above effects can be achieved.

<Polymer (A)> The liquid crystal alignment agent of the present invention contains at least one polymer (A) selected from the group consisting of a polyimide precursor having a repeating unit (a1) represented by the following formula (1) and a polyimide as an imide compound of the polyimide precursor. In addition, the polymer (A) may be one kind or composed of two or more kinds.

[Chemistry 2]

R and Z each independently represent a hydrogen atom or a monovalent organic group.

In the above formula (1), the monovalent organic group of R and Z is, for example, a monovalent alkyl group having 1 to 20 carbon atoms, the methylene group of the alkyl group being -O-, -S-, -CO-, -COO-, -COS-, -NR ³ -, -CO-NR ³ -, -Si(R ³ ) ₂ - (however, R ³ is a hydrogen atom or a monovalent alkyl group having 1 to 10 carbon atoms, and when there are multiple R ³ , each R ³ may be the same or different.), -SO ₂ -, a monovalent group A substituted with a halogen atom (fluorine atom, chlorine atom, bromine atom, iodine atom, etc.), a hydroxyl group, an alkoxyl group, a nitro group, an amino group, a nitroso group, an alkylsilyl group, an alkoxysilyl group, a silanol group, a sulfinic acid group, a phosphino group, a carboxyl group, a cyano group, a sulfonic acid group, an acyl group, etc., a monovalent group having a heterocyclic ring, etc. In the above formula (1), the monovalent organic group of R and Z is preferably an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an alkynyl group having 2 to 10 carbon atoms, Boc, or Fmoc, more preferably an alkyl group having 1 to 3 carbon atoms, and more preferably a methyl group.

From the viewpoint of ideally obtaining the effects of the present invention, R and Z are each independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, preferably a hydrogen atom or a methyl group, more preferably.

From the viewpoint of obtaining the effects of the present invention in an ideal manner, the polymer (A) may be at least one polymer selected from the group consisting of a polyimide precursor having both a repeating unit (a1) represented by the above formula (1) and a repeating unit (a2) represented by the following formula (2), and a polyimide which is an imide product of the polyimide precursor. The repeating unit (a2) may be one type or may be composed of two or more types.

[Chemistry 3]

In the above formula (2), R and Z have the same meanings as in the above formula (1). _Y2 represents a divalent organic group represented by the following formula (O).

[Chemistry 4]

In the above formula (O), Ar each independently represents a benzene ring, a biphenyl structure, or a naphthalene ring. Any hydrogen atom on the Ar ring may be substituted by a halogen atom or a monovalent organic group. _Q2 represents -( _CH2 ) _n- (n is 2 to 18), or a group in which a part of -( _CH2 ) _n- is substituted by any one of -O-, -C(=O)-, or -OC(=O)-.

In the above formula (O), the halogen atom is, for example, a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom. The monovalent organic group is, for example, an alkyl group having 1 to 3 carbon atoms, such as methyl, ethyl, propyl, and isopropyl; an alkenyl group having 2 to 3 carbon atoms, such as vinyl, propenyl, and butenyl; an alkynyl group having 2 to 3 carbon atoms, such as ethynyl, 1-propynyl, and 2-propynyl; and a monovalent organic group having 1 to 3 carbon atoms and containing fluorine atoms, such as fluoromethyl, trifluoromethyl, pentafluoroethyl, and pentafluoropropyl.

The divalent organic group represented by the above formula (O) is preferably a divalent organic group represented by any one of the following formulas (o-1) to (o-15) from the viewpoint of improving the liquid crystal alignment. In formula (o-10), m is preferably 2. In formula (o-14), m is more preferably 0 or 2.

[Chemistry 5]

[Chemistry 6]

In formula (o-14) to (o-15), the two m are independent of each other. From the viewpoint of ideally obtaining the effect of the present invention, the above-mentioned polymer (A) may also be at least one polymer selected from the group consisting of a polyimide precursor having a repeating unit (a1) represented by the above formula (1), or having at least one of the above repeating units (a1) and the repeating units (a2) represented by the above formula (2), and repeating units (a2') represented by the following formula (2') and repeating units (a3) represented by the following formula (3), and a polyimide which is an imide compound of the polyimide precursor.

[Chemistry 7]

In the above formula (2') and formula (3), X _2' and X ₃ represent a tetravalent organic group, Y _2' represents a divalent organic group represented by the following formula (O2), and Y ₃ represents a divalent organic group having a carbon number of 6 to 30 excluding D and having a group "-N(D)-(D represents a carbamate protective group)" in the molecule. R and Z have the same meanings as in the case of the above formula (1).

[Chemistry 8]

In the above formula (O2), m is an integer of 0 to 2, and Ar _2' represents an unsubstituted or substituted benzene ring. However, when m is 0, Ar _2' represents an unsubstituted benzene ring, and when m is 1 to 2, Ar _2' each independently represents an unsubstituted benzene ring, or a benzene ring in which any hydrogen atom on the benzene ring is substituted by a halogen atom or a monovalent organic group (for example, an alkyl group having 1 to 3 carbon atoms, an alkenyl group having 2 to 3 carbon atoms, an alkynyl group having 2 to 3 carbon atoms, a monovalent organic group having 1 to 3 carbon atoms and containing a fluorine atom, etc.). Q _2' represents a single bond, or -O-. When multiple Ar _2' and Q _2' exist, they may be the same or different.

From the viewpoint of ideally obtaining the effect of the present invention, the divalent organic group represented by the above formula (O2) is preferably a divalent organic group represented by any one of the following formulas (o2-1) to (o2-12).

[Chemistry 9]

In the above formula (3), D of Y ₃ represents a carbamate protecting group, and a carbamate protecting group is, for example, Boc or Fmoc. Specific examples of the above Y ₃ are, for example, a divalent organic group represented by the following formula (Dx).

[Chemistry 10]

In the above formula (Dx), _Q5 is a single bond, -( _CH2 ) _n- (n is 1 to 20), or a group in which any _-CH2- of the -( _CH2 ) _n- is substituted by -O-, -Si( _CH3 ) _2- , -COO-, -OCO-, _-NQ9- , -NQ9- _CO- , -CO- _NQ9- , _-NQ9 -CO- _NQ10- , _-NQ9- COO- or -O-COO-, and _Q9 and _Q10 each independently represent a hydrogen atom or a monovalent organic group.

Q ₆ and Q ₇ each independently represent -H, -NHD, -N(D) ₂ , a group having -NHD, or a group having -N(D) _2. However, when m=0, Q ₆ has a carbamate-based protecting group, and when m=1, at least one of Q ₅ , Q ₆ and Q ₇ has a carbamate-based protecting group in the group. Furthermore, when Q ₆ and Q ₇ represent a group having -NHD or a group having -N(D) ₂ , the number of carbon atoms of Q ₆ and Q ₇ other than D is preferably 1 to 10, more preferably 1 to 8.

The monovalent organic group of _Q9 and _Q10 is, for example, an alkyl group having 1 to 3 carbon atoms, an alkenyl group having 2 to 3 carbon atoms, an alkynyl group having 2 to 3 carbon atoms, a monovalent organic group having 1 to 3 carbon atoms containing a fluorine atom, Boc or Fmoc. Specific examples of the alkyl group having 1 to 3 carbon atoms, the alkenyl group having 2 to 3 carbon atoms, the alkynyl group having 2 to 3 carbon atoms, and the monovalent organic group having 1 to 3 carbon atoms containing a fluorine atom are, for example, the same structures as the monovalent organic group exemplified in the above formula (O).

A preferred specific example of _Y3 is a divalent organic group represented by any one of the following formulae (Y3-1) to (Y3-9), from the viewpoint of ideally obtaining the effects of the present invention.

[Chemistry 11]

X _2' and X ₃ in the above formula (2') and formula (3) are, for example, a quaternary organic group represented by the following formula (g), a quaternary organic group represented by any one of the following formulas (X-1) to (X-25), a quaternary organic group derived from an aromatic tetracarboxylic dianhydride, etc. From the viewpoint of ideally obtaining the effect of the present invention, X _2' and X ₃ are preferably quaternary organic groups represented by the following formula (g), and more preferably, a quaternary organic group represented by (g) in which R ₁ and R ₄ are methyl groups and R ₂ and R ₃ are hydrogen atoms.

[Chemistry 12]

R ₁ to R ₄ each independently represent a hydrogen atom, a halogen atom, 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, or a phenyl group, and at least one of R ₁ to R ₄ represents a group other than a hydrogen atom in the above definition.

[Chemistry 13]

[Chemistry 14]

In _the above formula (g), specific examples of alkyl groups having ₁ to 6 carbon atoms include methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, etc. Specific examples of alkenyl groups having 2 to 6 carbon atoms in the above R ₁ to R ₄ include vinyl, propenyl, butenyl, etc., which may be linear or branched. Specific examples of alkynyl groups having 2 to 6 carbon atoms in the above R ₁ to R ₄ include ethynyl, 1-propynyl, 2-propynyl, 1-butynyl, 2-butynyl, 3-butynyl, etc. Specific examples of monovalent organic groups having 1 to 6 carbon atoms and containing fluorine atoms in the above R ₁ to R ₄ include fluoromethyl, trifluoromethyl, pentafluoroethyl, pentafluoropropyl, etc.

The aromatic tetracarboxylic dianhydride is an acid dianhydride obtained by dehydrating the carboxyl group of an aromatic ring such as a benzene ring or a naphthalene ring through the molecular structure. For example, a tetravalent organic group represented by any one of the following formulas (Xa-1) to (Xa-2) or a tetravalent organic group represented by any one of the following formulas (Xr-1) to (Xr-7).

[Chemistry 15]

x and y are each independently a single bond, an ether, a carbonyl group, an ester, an alkanediyl group having 1 to 10 carbon atoms, a 1,4-phenylene group, a sulfonyl group, or an amide bond. j and k are 0 or 1.

[Chemistry 16]

The tetravalent organic group represented by the above formula (Xa-1) or (Xa-2) may also be a structure represented by any one of the following formulas (Xa-3) to (Xa-19).

[Chemistry 17]

[Chemistry 18]

The polymer (A) may be at least one polymer selected from the group consisting of a polyimide precursor having a repeating unit (a4) represented by the following formula (4) in addition to the repeating unit (a1), repeating unit (a2), repeating unit (a2′), and repeating unit (a3), and a polyimide which is an imide product of the polyimide precursor.

[Chemistry 19]

In the above formula (4), _X4 represents a quaternary organic group, and _Y4 represents a divalent organic group. R and Z are the same as R and Z in the above formula (1). However, _Y4 represents a structure having a group "-N(D)-(D represents a carbamate-based protective group)" in the molecule, and excluding a divalent organic group having 6 to 30 carbon atoms in D and a divalent organic group represented by the above formula (O2). In addition, when _X4 is a quaternary organic group represented by the above formula (g), _R1 and _R4 are methyl groups, and _R2 and _R3 are hydrogen atoms, _Y4 represents a structure other than 2-methyl-1,4-phenylene and a divalent organic group represented by the above formula (O).

Specific examples of _X4 include the tetravalent organic groups exemplified above as X2 _' . From the perspective of ideally achieving the effects of the present invention, _X4 is preferably a tetravalent organic group represented by the above formula (g) or a tetravalent organic group represented by any one of the above formulas (X-1) to (X-25), and a tetravalent organic group represented by the above formula (g) is more preferred.

Specific examples of the divalent organic group for _Y4 include the divalent organic groups exemplified in the above formula (O) and, for example, the divalent organic group derived from the diamine described below (a divalent organic group obtained by removing two amino groups from a diamine).

2,5-dimethyl-1,4-phenylenediamine, 2-fluoro-1,4-phenylenediamine, 2-methoxy-1,4-phenylenediamine, 2,5-dimethoxy-1,4-phenylenediamine, 4,4'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 3,3'-dimethyl-4,4'-diaminodiphenylmethane; diamines having a photo-alignment group such as diamines represented by the following formulas (g-1) to (g-9); diamines having a urea bond such as diamines represented by the following formulas (u-1) to (u-3) (however, the diamines do not have a carbamate protective group in the molecule); diamines represented by the following formulas (u-4) to (u-7) diamines having an amide bond, such as the diamines shown in the figure (but the diamines do not have a carbamate-based protective group in the molecule); diamines having at least one nitrogen-containing structure selected from the group consisting of a nitrogen-containing heterocycle, a diamine group, and a tertiary amine group (hereinafter also referred to as a nitrogen-containing structure. However, in the above-mentioned diamine groups and tertiary amine groups, the amine groups are not bonded to a carbamate-based protective group); 2,4-diaminophenol, 3,5-diaminophenol, 3,5-diaminobenzyl alcohol, 2,4-diaminobenzyl alcohol, 4,6-diaminoresorcinol; 2,4-diaminobenzoic acid, 2,5-diaminobenzoic acid, 3,5- Diamines having a carboxyl group, such as diaminobenzoic acid or diamine compounds represented by the following formula (3b-1) to (3b-4); 4-(2-(methylamino)ethyl)aniline, 4-(2-aminoethyl)aniline, 4,4'-diaminodiphenyl ketone, 1-(4-aminophenyl)-1,3,3-trimethyl-1H-dihydroindene-5-amine, 1-(4-aminophenyl)-2,3-dihydro-1,3,3-trimethyl-1H-indene-6-amine; diamines having a photopolymerizable group at the end, such as 2-(2,4-diaminophenoxy)ethyl methacrylate and 2,4-diamino-N,N-diallylaniline ; diamines having a steroid skeleton such as cholestanyloxy-3,5-diaminobenzene, cholestanyloxy-3,5-diaminobenzene, cholestanyloxy-2,4-diaminobenzene, 3,5-diaminobenzoic acid cholestanyl ester, 3,5-diaminobenzoic acid cholestanyl ester, 3,5-diaminobenzoic acid lanostanyl ester and 3,6-bis(4-aminobenzyloxy)cholestane; diamines represented by the following formulas (V-1) to (V-6); diamines having a siloxane bond such as 1,3-bis(3-aminopropyl)-tetramethyldisiloxane; diamines having an oxazoline ring structure such as the following formulas (Ox-1) and (Ox-2); A divalent organic group of a diamine such as a diamine having a free radical polymerization initiator function, such as 1-(4-(2-(2,4-diaminophenoxy)ethoxy)phenyl)-2-hydroxy-2-methylacetone, 2-(4-(2-hydroxy-2-methylpropionyl)phenoxy)ethyl-3,5-diaminobenzoate, 4,4'-diaminodiphenyl ketone, 3,3'-diaminodiphenyl ketone, or a group represented by any one of formulas (Y-1) to (Y-167) described in WO2018/117239.

[Chemistry 20]

[Chemistry 21]

[Chemistry 22]

In the above formula (3b-1), ^A1 represents a single bond, _-CH2- , _{-C2H4- ,} -C( _CH3 ) _2- , _-CF2- , -C( _CF3 ) _2- , -O-, -CO-, -NH-, -N( _CH3 )-, -CONH-, -NHCO-, -CH2O-, _-OCH2- , _-COO- , -OCO-, -CON( _CH3 )- or -N( _CH3 )CO-, m1 and m2 each independently represent 0 to 4, and the total of m1 and m2 is 1 to 4.

In the above formula (3b-2), m3 and m4 each independently represent 1 to 5. In the above formula (3b-3), ^A2 represents a linear or branched alkyl group having 1 to 5 carbon atoms, and m5 is 1 to 5. In the above formula (3b- ₄ ), ^A3 and ^A4 each independently represent a single bond, _-CH2- , _-C2H4- , -C( _CH3 ) _2- , _-CF2- , -C( _CF3 ) _2- , -O-, -CO-, -NH-, -N( _CH3 )-, -CONH-, -NHCO-, _-CH2O- , _-OCH2- , -COO-, -OCO-, -CON( _CH3 )- or -N( _CH3 )-CO-, and m6 is 1 to 4.

[Chemistry 23]

In the above formulae (V-1) to (V-6), ^Xv1 to ^Xv4 and ^Xp1 to ^Xp2 each independently represent -( _CH2 ) _a- (a is 1 to 15), -CONH-, -NHCO-, -CON( _CH3 )-, -NH-, _-O- , _-CH2O- , -CH2OCO-, -COO-, or -OCO-, and ^Xv5 represents _-O- , _-CH2O- , -CH2OCO-, -COO-, or -OCO-. _Xa represents a single bond, -O-, -NH-, -O-( _CH2 ) _m -O- (m is 1 to 6), -C( _CH3 ) _2- , -CO-, -( _CH2 ) _m- (m is 1 to 6), _-SO2- , -OC( _CH3 ) _2- , -CO-( _CH2 ) _m- (m is 1 to 6), -NH-( _CH2 ) _m- (m is 1 to 6), _-SO2- ( _CH2 ) _m- (m is 1 to 6), -CONH-( _CH2 ) _m- (m is 1 to 6), -CONH-( _CH2 ) _m -NHCO- (m is 1 to 6), -COO-( _CH2 ) _m -OCO- (m is 1 to 6), -CONH-, -NH-( _CH2 ) _m -NH- (m is 1 to 6), or _-SO2- ( _CH2 ) _m - _SO2- (m is 1 to 6), ^Rv1 to ^Rv4 and ^R1a to ^R1b 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. k may be the same or different.

[Chemistry 24]

The above-mentioned nitrogen-containing heterocyclic ring includes, for example, pyrrole, imidazole, pyrazole, triazole, pyridine, pyrimidine, phthalimide, pyrrolidine, indole, benzimidazole, purine, quinoline, isoquinoline, oxadiazole, quinoline, phthalimide, triazole, carbazole, acridine, piperidine, piperidine, pyrrolidine, hexamethyleneimine, etc. Among them, pyridine, pyrimidine, pyrrolidine, piperidine, piperidine, quinoline, carbazole or acridine is preferred.

The diamine having a structure containing a nitrogen atom may also have a secondary amine group and a tertiary amine group, which are represented by the following formula (n), for example.

[Chemistry 25]

In the above formula (n), R represents a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. "*1" represents an atomic bond to the hydrocarbon group. The monovalent hydrocarbon group of R in the above formula (n) is, for example, an alkyl group such as methyl, ethyl, propyl, etc.; a cycloalkyl group such as cyclohexyl, etc.; an aryl group such as phenyl, methylphenyl, etc. R is preferably a hydrogen atom or a methyl group.

Specific examples of diamines having a structure containing a nitrogen atom include 2,6-diaminopyridine, 3,4-diaminopyridine, 2,4-diaminopyrimidine, 3,6-diaminocarbazole, N-methyl-3,6-diaminocarbazole, N-ethyl-3,6-diaminocarbazole, N-phenyl-3,6-diaminocarbazole, 1,4-bis-(4-aminophenyl)-piperidinium, 3,6-diaminoacridine, compounds represented by the following formulas (Dp-1) to (Dp-8), or compounds represented by the following formulas (z-1) to (z-13).

[Chemistry 26]

[Chemistry 27]

[Chemistry 28]

From the viewpoint of ideally obtaining the effect of the present invention, in the polymer (A), the total content of the repeating unit (a1) and the imidized structural unit of the repeating unit (a1) is preferably 10 to 100 mol% of all the repeating units, and more preferably 15 to 100 mol%. In addition, the total here also includes the case where either the repeating unit (a1) or the imidized structural unit of the repeating unit (a1) is 0 mol%. Hereinafter, when referring to the total, it also includes the case where one or more of the constituent unit elements are 0 mol%.

When the polymer (A) contains repeating units other than the imidized structural units of the repeating units (a1) and the repeating units (a1), the total content of the repeating units (a1) and the imidized structural units of the repeating units (a1) is preferably 10 to 95 mol% of the total repeating units. In the polymer (A), the total content of the repeating units (a1) and the imidized structural units of the repeating units (a1) is preferably 95 mol% or less, more preferably 90 mol% or less, and more preferably 80 mol% or less of the total repeating units. In addition, in the polymer (A), the total content of the repeating units (a1) and the imidized structural units of the repeating units (a1) is preferably 10 mol% or more, and more preferably 15 mol% or more of the total repeating units.

From the viewpoint of ideally obtaining the effect of the present invention, in the polymer (A), the total content of the repeating unit (a2) and the imidized structural unit of the repeating unit (a2) is preferably 5 mol% or more, more preferably 10 mol% or more, more preferably 20 mol% or more of the total repeating units, and on the other hand, it is preferably 90 mol% or less, and more preferably 85 mol% or less. In addition, from the viewpoint of ideally obtaining the effect of the present invention, in the aforementioned polymer (A), the total content of the aforementioned repeating unit (a2) and the imidized structural unit of the aforementioned repeating unit (a2) is preferably 10-90 mol% of the total repeating units.

From the viewpoint of ideally obtaining the effects of the present invention, in polymer (A), the total content of repeating units (a1), repeating units (a2), and their imidized structural units is preferably 10 mol% or more of all repeating units, and more preferably 20 mol% or more. When repeating units other than repeating units (a1), repeating units (a2), and their imidized structural units are contained, the total content of repeating units (a1), repeating units (a2), and their imidized structural units is preferably 95 mol% or less, and more preferably 90 mol% or less.

When the polymer (A) contains at least one of the repeating unit (a2') and the imidized structural unit of the repeating unit (a2'), from the viewpoint of ideally obtaining the effect of the present invention, the total content of the repeating unit (a2') and the imidized structural unit of the repeating unit (a2') in the polymer (A) is preferably 1 to 50 mol %, more preferably 1 to 40 mol %, and even more preferably 1 to 30 mol % of all the repeating units. When the polymer (A) contains at least one of the repeating unit (a1) and its imidized structural unit and contains at least one of the repeating unit (a2) and its imidized structural unit, the total content of the repeating unit (a2') and the imidized structural unit of the repeating unit (a2') is preferably 5 mol% or more, and more preferably 10 mol% or more.

From the viewpoint of ideally obtaining the effect of the present invention, the polymer (A) contains at least one of the repeating unit (a1) and its imidized structural unit, at least one of the repeating unit (a2) and its imidized structural unit, and at least one of the repeating unit (a2′) and its imidized structural unit, and the total content of the repeating unit (a1), the repeating unit (a2), the repeating unit (a2′), and their imidized structural units is preferably 30 mol% or more, and more preferably 40 mol% or more, of all the repeating units. When the polymer (A) contains repeating units (a1), repeating units (a2), repeating units (a2'), and repeating units other than imide structural units thereof, the total content of repeating units (a1), repeating units (a2), repeating units (a2'), and their imide structural units is preferably 95 mol % or less, and more preferably 90 mol % or less.

When the polymer (A) contains at least one of the repeating unit (a3) and the imidized structure unit of the repeating unit (a3), from the viewpoint of ideally obtaining the effect of the present invention, the total content of the repeating unit (a3) and the imidized structure unit of the repeating unit (a3) in the polymer (A) is preferably 1 to 40 mol %, more preferably 1 to 30 mol %, and even more preferably 1 to 25 mol % of all the repeating units.

The polymer (A) may also contain repeating units (a2'), repeating units (a3), and imidized structural units thereof.

When the polymer (A) contains at least any one of the above-mentioned repeating units (a4) and their imidized structural units, it is preferably composed of at least any one of the repeating units (a4) and their imidized structural units in which _Y4 is a divalent organic group having no side chain structure with more than 4 carbon atoms, from the viewpoint of ideally obtaining the effect of the present invention.

The above-mentioned divalent organic group having no side chain structure with more than 4 carbon atoms is, for example, a divalent organic group of a diamine selected from the group consisting of the above-mentioned other diamines excluding 2-(2,4-diaminophenoxy)ethyl methacrylate, 2,4-diamino-N,N-diallylaniline, the above-mentioned diamine having a steroid skeleton, the diamine represented by the above formula (V-1) to (V-6), 1-(4-(2,4-diaminophenoxy)ethoxy)phenyl)-2-hydroxy-2-methylacetone, 2-(4-(2-hydroxy-2-methylpropionyl)phenoxy)ethyl-3,5-diaminobenzoate, N-phenyl-3,6-diaminocarbazole, and the diamine represented by (z-4) and (z-6).

When the polymer (A) contains at least one of the repeating unit (a4) and the imidized structure unit of the repeating unit (a4), from the viewpoint of ideally obtaining the effect of the present invention, the total content of the repeating unit (a4) and the imidized structure unit of the repeating unit (a4) in the polymer (A) is preferably 1 to 90 mol %, more preferably 5 to 70 mol %, and even more preferably 10 to 30 mol % of all the repeating units. In order to ideally obtain the effect of the present invention, the total content of repeating units of the above formula (g) having a quaternary organic group in which _R1 and _R4 are methyl groups and _R2 and _R3 are hydrogen atoms in the polymer (A) is preferably 50 mol% or more, more preferably 80 mol% or more, and most preferably 100 mol% of all repeating units having a quaternary organic group derived from tetracarboxylic dianhydride or its derivatives possessed by the polymer (A). ＜Polymer (B)＞ The liquid crystal alignment agent of the present invention may contain, in addition to the above polymer (A), a polymer (B) having no repeating unit (a1) in the molecule. In addition, the polymer (B) may be one kind or composed of two or more kinds. From the viewpoint of ideally obtaining the effects of the present invention, the polymer (B) is, for example, a polymer having at least one repeating unit selected from the group consisting of a repeating unit (b1) represented by the following formula (5) and an imidized structural unit of the repeating unit (b1), and more preferably a polyamide having a repeating unit (b1) represented by the following formula (5). The repeating unit constituting the polymer (B) may be one type or may be composed of two or more types.

[Chemistry 29]

In the above formula (5), _X5 is a tetravalent organic group, and _Y5 is a divalent organic group. R and Z have the same meanings as R and Z in the above formula (1).

The tetravalent organic group of X ₅ is, for example, a tetravalent organic group derived from aliphatic tetracarboxylic dianhydride, a tetravalent organic group derived from alicyclic tetracarboxylic dianhydride, or a tetravalent organic group derived from aromatic tetracarboxylic dianhydride, and a specific example is the tetravalent organic group exemplified above for X _4. In view of obtaining the effect of the present invention, the aliphatic or alicyclic tetracarboxylic dianhydride is preferably a tetracarboxylic dianhydride having at least one substructure selected from the group consisting of a cyclobutane ring structure, a cyclopentane ring structure, and a cyclohexane ring structure from the viewpoint of improving the alignment of liquid crystals. More preferably, X ₅ is a tetravalent organic group represented by the above formula (g), a tetravalent organic group represented by any of the above formulas (X-1) to (X-25), a tetravalent organic group represented by the above formulas (Xa-1) to (Xa-2), or a tetravalent organic group represented by the above formulas (Xr-1) to (Xr-7) (these are also collectively referred to as specific tetravalent organic groups).

In polymer (B), from the viewpoint of obtaining the effect of the present invention, the content of repeating units in which _X5 is the above-mentioned specific tetravalent organic group is preferably 5 mol% or more, and more preferably 10 mol% or more of all repeating units contained in polymer (B).

The divalent organic group of Y ₅ is, for example, the divalent organic group exemplified above for Y _4. From the viewpoint of less residual DC residue, the polymer (B) is preferably a polymer containing repeating units of a divalent organic group wherein Y ₅ is derived from the diamine having a urea bond, the diamine having an amide bond, the diamine having a structure containing a nitrogen atom, 2,4-diaminophenol, 3,5-diaminophenol, 3,5-diaminobenzyl alcohol, 2,4-diaminobenzyl alcohol, 4,6-diaminoresorcinol, the diamine having a carboxyl group, 4,4'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, p-phenylenediamine, or m-phenylenediamine (these are also collectively referred to as specific divalent organic groups).

From the viewpoint of improving transmittance, the polymer (B) preferably has two or more repeating units represented by the above formula (5), and preferably contains repeating units having a divalent organic group Y ₅ derived from the above-mentioned diamine having a urea bond, the above-mentioned diamine having an amide bond, or the above-mentioned diamine having a structure containing a nitrogen atom, and preferably contains repeating units having another divalent organic group Y ₅ derived from a diamine.

In polymer (B), from the viewpoint of leaving less residual DC, _Y5 is the content of the repeating unit of the specific divalent organic group, and may be 1 mol% or more of all the repeating units contained in polymer (B), preferably 5 mol% or more, more preferably 10 mol% or more, and even more preferably 20 mol% or more. From the viewpoint of leaving less residual DC, the content ratio of polymer (A) to polymer (B) (mass ratio of polymer (A)/polymer (B)) is preferably 10/90 to 90/10, more preferably 20/80 to 90/10, and even more preferably 20/80 to 80/20. <Method for producing polymer (A) and polymer (B)> In the present invention, the polyimide precursor, polyamic acid ester, polyamic acid, and imide products thereof, i.e., polyimide, which are polymers (A) and (B), can be synthesized by a known method such as that described in WO2013/157586.

Specifically, the synthesis is performed by reacting a diamine component and a tetracarboxylic acid derivative component in a solvent (condensation polymerization). The tetracarboxylic acid derivative component is, for example, tetracarboxylic dianhydride or its derivative (tetracarboxylic acid dihalide, tetracarboxylic acid diester, or tetracarboxylic acid diester dihalide). When a part of the polymer (A) or (B) contains an acylamidic acid structure, for example, a polymer having an acylamidic acid structure (polyacylamidic acid) can be obtained by reacting a tetracarboxylic dianhydride component with a diamine component. The solvent is not particularly limited as long as the generated polymer can be dissolved.

In order to obtain the diamine component and the tetracarboxylic acid derivative component of the polyimide precursor of the polymer (A), the structure of the repeating unit can be obtained by selecting the repeating unit represented by the above formula (1), formula (2), formula (2'), formula (3) and formula (4) possessed by the polymer (A).

For example, when the polymer (A) has a repeating unit represented by the formula (1), a diamine having a structure of -N(Z)-Y ₁ -N(Z)- (Y ₁ represents 2-methyl-1,4-phenylene group. Z has the same definition as above) (hereinafter also referred to as specific diamine) is used as the diamine component, and a tetracarboxylic acid derivative having a structure of the following formula (mt) is used as the tetracarboxylic acid derivative component.

[Chemistry 30]

The diamine component and the tetracarboxylic acid derivative component used to obtain the polyimide precursor of the polymer (A) having the repeating units represented by the formula (2), the formula (2'), the formula (3) and the formula (4) possessed by the polymer (A) can be selected and used respectively according to the diamine and the tetracarboxylic acid derivative used to obtain the polyimide precursor having the repeating units represented by the above formula (1).

Furthermore, the diamine component and the tetracarboxylic acid derivative component of the polyimide precursor for obtaining the polymer (B) are each selected to obtain the structure of the repeating unit represented by the above formula (5) possessed by the polymer (B). That is, the diamine component is a diamine having a structure of -N(Z)-Y ₅ -N(Z)- (Y ₅ and Z have the same definitions as above), and the tetracarboxylic acid derivative component is a tetracarboxylic acid derivative having a structure of X ₅ (X ₅ has the same definition as above).

Specific examples of the above-mentioned solvent when the diamine component and the tetracarboxylic acid derivative component are reacted include N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, γ-butyrolactone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethylsulfoxide, and 1,3-dimethyl-2-imidazolidinone. In addition, when the polymer has high solvent solubility, methyl ethyl ketone, cyclohexanone, cyclopentanone, 4-hydroxy-4-methyl-2-pentanone, or solvents represented by the following formulas [D-1] to [D-3] can be used.

[Chemistry 31]

In formula [D-1], ^D1 represents an alkyl group having 1 to 3 carbon atoms, in formula [D-2], ^D2 represents an alkyl group having 1 to 3 carbon atoms, and in formula [D-3], ^D3 represents an alkyl group having 1 to 4 carbon atoms.

These solvents may be used alone or in combination. Furthermore, even a solvent in which the polymer is insoluble may be mixed with the above solvents to the extent that the generated polymer does not precipitate.

When the diamine component and the tetracarboxylic acid derivative component are reacted in a solvent, the reaction can be carried out at any concentration, but is preferably 1 to 50% by mass, more preferably 5 to 30% by mass. The reaction may be carried out at a high concentration in the initial stage, and then the solvent may be added.

In the reaction, the ratio of the total molar number of the diamine component to the total molar number of the tetracarboxylic acid derivative component (total molar number of the tetracarboxylic acid derivative component/total molar number of the diamine component) is preferably 0.8 to 1.2. As in a conventional polycondensation reaction, the closer this molar ratio is to 1.0, the greater the molecular weight of the generated polymer (A) and polymer (B).

The polyamic acid ester can be obtained by a known method such as [I] a method of reacting the polyamic acid obtained by the above method with an esterifying agent, [II] a method of reacting a tetracarboxylic acid diester with a diamine, or [III] a method of reacting a tetracarboxylic acid diester dihalide with a diamine.

The method for obtaining polyimide may include directly heating a solution containing a polyimide precursor such as polyamic acid, polyamic acid ester, etc. obtained by the above reaction for thermal imidization, or adding a catalyst to the above solution for catalytic imidization.

The polyimide in the polymer (A) of the present invention is a polyimide precursor having partially or completely closed ring repeating units. In the polyimide, the imidization rate is preferably 20-95%, preferably 30-95%, and more preferably 50-95%. ＜Solution viscosity and molecular weight of polymer＞ The polyamine acid, polyamine ester and polyimide in the polymer (A) of the present invention are preferably prepared into a solution with a concentration of 10-15 mass %, for example, with a solution viscosity of 10-1000 mPa·s from the viewpoint of workability, but there is no special restriction. In addition, the solution viscosity (mPa・s) of the above polymer is the value measured at 25°C using an E-type rotational viscometer to prepare a polymer solution with a concentration of 10~15 mass% using a good solvent for the polymer (e.g., γ-butyrolactone, N-methyl-2-pyrrolidone, etc.).

The weight average molecular weight (Mw) of the polyamine, polyamine ester and polyimide measured by gel permeation chromatography (GPC) in terms of polystyrene is preferably 1,000 to 500,000, more preferably 2,000 to 300,000. In addition, the molecular weight distribution (Mw/Mn) represented by the ratio of Mw to the number average molecular weight (Mn) measured by GPC in terms of polystyrene is preferably 15 or less, more preferably 10 or less. Within this molecular weight range, good orientation and stability of the liquid crystal display element can be ensured. <End Capping Agent> When synthesizing the polymer (A) and polymer (B) of the present invention, the tetracarboxylic acid derivative component and the diamine component as described above, as well as an appropriate end capping agent, can be used to prepare an end-sealed polymer. The end-sealed polymer has the effect of increasing the film hardness of the liquid crystal alignment film obtained by coating and improving the adhesion between the sealant and the liquid crystal alignment film.

The terminal of polymer (A) and polymer (B) in the present invention is, for example, an amine group, a carboxyl group, an anhydride group or a derivative thereof. The amine group, the carboxyl group, the anhydride group, and the isocyanate group can be obtained by a conventional condensation reaction, or by sealing the terminal with the following end-capping agent, for example, the following end-capping agent can be used to obtain the same.

End-capping agents, for example: acetic anhydride, maleic anhydride, neddic anhydride, phthalic anhydride, itaconic anhydride, cyclohexanedicarboxylic anhydride, 3-hydroxyphthalic anhydride, trimellitic anhydride, 3-(3-trimethoxysilyl)propyl)-3,4-dihydrofuran-2,5-dione, 4,5,6,7-tetrafluoroisobenzofuran-1,3-dione, 4-ethynylphthalic anhydride and other acid anhydrides; dicarbonic acid diester compounds such as di-tert-butyl dicarbonate and diallyl dicarbonate; chlorocarbonyl compounds such as acrylyl chloride, methacrylic chloride, nicotinyl chloride; aniline, 2- -aminophenol, 3-aminophenol, 4-aminosalicylic acid, 5-aminosalicylic acid, 6-aminosalicylic acid, 2-aminobenzoic acid, 3-aminobenzoic acid, 4-aminobenzoic acid, cyclohexylamine, n-butylamine, n-pentylamine, n-hexylamine, n-heptylamine, n-octylamine and the like monoamine compounds; isocyanate compounds having unsaturated bonds such as ethyl isocyanate, phenyl isocyanate, naphthyl isocyanate, 2-acryloyloxyethyl isocyanate and 2-methacryloyloxyethyl isocyanate and the like monoisocyanate compounds; isothiocyanate compounds such as ethyl isothiocyanate and allyl isothiocyanate and the like.

The use ratio of the end-capping agent is preferably 0.01 to 20 moles, and more preferably 0.01 to 10 moles, relative to 100 moles of the total diamine components used. <Liquid crystal alignment agent> The liquid crystal alignment agent of the present invention contains polymer (A) and, if necessary, polymer (B). The liquid crystal alignment agent of the present invention may contain other polymers in addition to polymer (A) and polymer (B). Specific examples of other polymers include polymers selected from the group consisting of polysiloxane, polyester, polyamide, polyurea, polyurethane, polyorganosiloxane, cellulose derivatives, polyacetal, polystyrene derivatives, poly(styrene-maleic anhydride) copolymers, poly(isobutylene-maleic anhydride) copolymers, poly(vinyl ether-maleic anhydride) copolymers, poly(styrene-phenylmaleimide) derivatives, and poly(meth)acrylates.

Specific examples of poly(styrene-maleic anhydride) copolymers include SMA1000, 2000, 3000 (manufactured by Cray Valley Corporation), GSM301 (manufactured by GIFUSHELLAC Manufacturing Co., Ltd.), etc. Specific examples of poly(isobutylene-maleic anhydride) copolymers include ISOBAM-600 (manufactured by Kuraray Corporation), and specific examples of poly(vinyl ether-maleic anhydride) copolymers include Gantrez AN-139 (methyl vinyl ether maleic anhydride resin, manufactured by ASHLAND Corporation). Other polymers may be used alone or in combination of two or more. The content ratio of other polymers relative to 100 parts by weight of the total polymers contained in the liquid crystal alignment agent is preferably 90 parts by weight or less, more preferably 10 to 90 parts by weight, and even more preferably 20 to 80 parts by weight.

The liquid crystal alignment agent is used to make a liquid crystal alignment film. Considering the formation of a uniform film, it is in the form of a coating liquid. The liquid crystal alignment agent of the present invention is preferably a coating liquid containing the above-mentioned polymer component and an organic solvent. At this time, the concentration of the polymer in the liquid crystal alignment agent can be appropriately changed according to the setting of the thickness of the coating to be formed. Considering the formation of a uniform and defect-free coating, it is ideal to be more than 1% by mass, and considering the storage stability of the solution, it is preferably less than 10% by mass. In particular, the ideal polymer concentration is 2~8% by mass.

The organic solvent contained in the liquid crystal alignment agent is not particularly limited as long as the polymer component can be uniformly dissolved. Specific examples thereof include N,N-dimethylformamide, N,N-dimethylacetamide, N,N-dimethyllactamide, N,N-dimethylpropionamide, tetramethylurea, N,N-diethylformamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, dimethylsulfoxide, γ-butyrolactone, γ-valerolactone, 1,3-dimethyl-2-imidazolidinone, methyl ethyl ketone, cyclohexanone, cyclopentanone, 3-methoxy-N,N-dimethylpropionamide, 3-butoxy The good solvents include N-(n-propyl)-2-pyrrolidone, N-isopropyl-2-pyrrolidone, N-(n-butyl)-2-pyrrolidone, N-(tert-butyl)-2-pyrrolidone, N-(n-pentyl)-2-pyrrolidone, N-methoxypropyl-2-pyrrolidone, N-ethoxyethyl-2-pyrrolidone, N-methoxybutyl-2-pyrrolidone, and N-cyclohexyl-2-pyrrolidone (these are also collectively referred to as "good solvents"). Among them, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, 3-methoxy-N,N-dimethylpropionamide, 3-butoxy-N,N-dimethylpropionamide or γ-butyrolactone is preferred. The content of the good solvent is preferably 20-99 mass % of the total solvent contained in the liquid crystal alignment agent, more preferably 20-90 mass % and even more preferably 30-80 mass % .

In addition, the organic solvent contained in the liquid crystal alignment agent is preferably a mixed solvent containing, in addition to the above solvents, a solvent (also called a bad solvent) for improving the coating property and surface smoothness of the coating film when the liquid crystal alignment agent is applied. The content of the bad solvent is preferably 1-80% by mass of the total solvent contained in the liquid crystal alignment agent, 10-80% by mass is more preferred, and 20-70% by mass is particularly preferred. The type and content of the bad solvent can be appropriately selected according to the coating device, coating conditions, coating environment, etc. of the liquid crystal alignment agent.

Specific examples of the above-mentioned bad solvent are as follows, but are not limited thereto.

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 monomethyl ether, propylene glycol monobutyl ether, 1-(2-butoxyethoxy)-2-propanol, 2-(2-butoxyethoxy)-2-propanol, )-1-propanol, propylene glycol monomethyl ether acetate, propylene glycol diacetate, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol dimethyl ether, ethylene glycol monobutyl ether acetate, diethylene glycol monopropyl ether, 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 ether, cyclohexyl acetate, 4-methyl-2-pentyl acetate, 3-methoxypropionic acid methyl ester, 3-ethoxypropionic acid ethyl ester, 3-methoxypropionic acid ethyl ester, 3-methoxypropionic acid propyl ester, 3-methoxypropionic acid butyl ester, n-butyl lactate, isoamyl lactate, diethylene glycol monoethyl ether, diisobutyl ketone (2,6-dimethyl-4-heptanone), etc.

Among the poor 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 is preferred.

Ideal solvent combinations of good solvents and poor solvents, such as 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-ethyl-2-pyrrolidone and 4-hydroxy-4-methyl-2-pentanone, N-ethyl-2-pyrrolidone and propylene glycol diacetate, N,N-dimethyl lactamide and diisopropyl ester. Butyl ketone, N-methyl-2-pyrrolidone and ethyl 3-ethoxypropionate, N-ethyl-2-pyrrolidone and ethyl 3-ethoxypropionate, N-methyl-2-pyrrolidone and ethyl 3-ethoxypropionate and dipropylene glycol monomethyl ether, N-ethyl-2-pyrrolidone and ethyl 3-ethoxypropionate and propylene glycol monobutyl ether, N-methyl-2-pyrrolidone and ethyl 3-ethoxypropionate and diethylene glycol monopropyl ether, N-ethyl-2-pyrrolidone and ethyl 3-ethoxypropionate and diethylene glycol monopropyl ether, N-Methyl-2-pyrrolidone and ethylene glycol monobutyl ether acetate, N-ethyl-2-pyrrolidone and dipropylene glycol dimethyl ether, N,N-dimethyl lactamide and ethylene glycol monobutyl ether, N,N-dimethyl lactamide and propylene glycol diacetate, N-ethyl-2-pyrrolidone and diethylene glycol diethyl ether, N-ethyl-2-pyrrolidone and diethylene glycol monoethyl ether and butyl cylosulacetate, N-methyl-2-pyrrolidone and diethylene glycol monomethyl ether and butyl cylosulacetate, N,N-dimethyl lactamide With diethylene glycol diethyl ether, N-methyl-2-pyrrolidone and gamma-butyrolactone and 4-hydroxy-4-methyl-2-pentanone with diethylene glycol diethyl ether, N-ethyl-2-pyrrolidone and N-methyl-2-pyrrolidone and 4-hydroxy-4-methyl-2-pentanone, N-ethyl-2-pyrrolidone and 4-hydroxy-4-methyl-2-pentanone with propylene glycol monobutyl ether, N-methyl-2-pyrrolidone and 4-hydroxy-4-methyl-2-pentanone with diisobutyl ketone, N-methyl-2-pyrrolidone and 4-Hydroxy-4-methyl-2-pentanone and dipropylene glycol monomethyl ether, N-methyl-2-pyrrolidone and 4-hydroxy-4-methyl-2-pentanone and propylene glycol monobutyl ether, N-methyl-2-pyrrolidone and 4-hydroxy-4-methyl-2-pentanone and propylene glycol diacetate, N-ethyl-2-pyrrolidone and 4-hydroxy-4-methyl-2-pentanone and dipropylene glycol dimethyl ether, γ-butyrolactone and 4-hydroxy-4-methyl-2-pentanone and diisobutyl ketone, γ-butyrolactone and 4-hydroxy-4- Methyl-2-pentanone and propylene glycol diacetate, N-methyl-2-pyrrolidone and γ-butyrolactone 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, N-methyl-2-pyrrolidone and γ-butyrolactone and dipropylene glycol dimethyl ether, N-methyl-2-pyrrolidone and γ-butyrolactone and dipropylene glycol dimethyl ether, N-ethyl-2 -Pyrrolidone and propylene glycol monobutyl ether and dipropylene glycol monomethyl ether, N-ethyl-2-pyrrolidone and diethylene glycol diethyl ether and dipropylene glycol monomethyl ether, N-ethyl-2-pyrrolidone and propylene glycol monobutyl ether and propylene glycol diacetate, N-ethyl-2-pyrrolidone and propylene glycol monobutyl ether and diisobutyl ketone, N-ethyl-2-pyrrolidone and γ-butyrolactone and diisobutyl ketone, N-ethyl-2-pyrrolidone and N,N-dimethyllactamide and diisobutyl ketone, N-methyl-2-pyrrolidone and ethyl Glycol monobutyl ether and ethylene glycol monobutyl ether acetate, γ-butyrolactone and ethylene glycol monobutyl ether acetate and dipropylene glycol dimethyl ether, N-ethyl-2-pyrrolidone and ethylene glycol monobutyl ether acetate and propylene glycol dimethyl ether, N-methyl-2-pyrrolidone and 4-methyl-2-pentyl acetate and ethylene glycol monobutyl ether, N-ethyl-2-pyrrolidone and cyclohexyl acetate and diacetone alcohol cyclohexanone and propylene glycol monomethyl ether, cyclopentanone and propylene glycol monomethyl ether, N-methyl-2-pyrrolidone and cyclohexanone and propylene glycol monomethyl ether, etc.

The liquid crystal alignment agent of the present invention may also contain additional components other than the polymer component and the organic solvent (hereinafter also referred to as additive components). Such additive components include: adhesion aids for improving the adhesion between the liquid crystal alignment film and the substrate, and 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), compounds for promoting imidization, dielectrics for adjusting the dielectric constant and resistance of the liquid crystal alignment film, conductive substances, etc.

With respect to the above-mentioned crosslinking compound, from the viewpoint of ideally obtaining the effect of the present invention, there can be cited compounds having at least one group selected from the group consisting of an oxirane group, a propylene oxide group, a protected isocyanate group, a protected isothiocyanate group, a group containing an oxazoline ring structure, a group containing a Meldrum's acid structure, a cyclic carbonate group, and a group represented by the following formula (d), or a compound represented by the following formula (e).

[Chemistry 32]

In the above formula (d), R ₂ and R ₃ are each independently a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or "*-CH ₂ -OH". In the above formula (e), A represents an (m+n)-valent organic group having an aromatic ring, R and R' are each independently a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, m is 1 to 6, and n is 0 to 4. Any hydrogen atom in the above aromatic ring may be substituted by a halogen atom, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a fluoroalkyl group having 1 to 10 carbon atoms, a fluoroalkenyl group having 2 to 10 carbon atoms, or a fluoroalkoxy group having 1 to 10 carbon atoms.

Specific examples of compounds having an oxirane group include compounds described in [0037] of Japanese Patent Application Laid-Open No. 10-338880 and compounds having a tricyclic ring in the skeleton described in WO2017/170483. Among them, compounds containing nitrogen atoms such as N,N,N',N'-tetraoxopropyl-m-xylene diamine, 1,3-bis(N,N-dioxopropylaminomethyl)cyclohexane, N,N,N',N'-tetraoxopropyl-4,4'-diaminodiphenylmethane, N,N,N',N'-tetraoxopropyl-p-phenylenediamine, and compounds represented by the following formulas (r-1) to (r-3) may be mentioned.

[Chemistry 33]

Specific examples of the compound having an propylene oxide group include compounds having two or more propylene oxide groups described in [0170] to [0175] of WO2011/132751.

Specific examples of the compound having a protected isocyanate group include compounds having two or more protected isocyanate groups described in [0046] to [0047] of JP-A-2014-224978, compounds having three or more protected isocyanate groups described in [0119] to [0120] of WO2015/141598, and compounds represented by the following formulas (bi-1) to (bi-3).

[Chemistry 34]

Specific examples of the compound having a protected isothiocyanate group include compounds having two or more protected isothiocyanate groups described in Japanese Patent Application Laid-Open No. 2016-200798.

Specific examples of the compound having a group containing an oxazoline ring structure include compounds containing two or more oxazoline ring structures described in [0115] of JP-A-2007-286597.

Specific examples of the compound having a group containing a Michaelis acid structure include compounds having two or more Michaelis acid structures described in WO2012/091088.

Specific examples of the compound having a cyclocarbonate group include the compounds described in WO2011/155577.

The alkyl group having 1 to 3 carbon atoms in R ₂ and R ₃ of the group represented by the above formula (d) may be methyl, ethyl, propyl or isopropyl.

Specific examples of the compound having a group represented by the above formula (d) include compounds having two or more groups represented by the above formula (d) described in [0058] of WO2015/072554, Japanese Patent Application Publication No. 2016-118753, compounds described in Japanese Patent Application Publication No. 2016-200798, and compounds represented by the following formulas (hd-1) to (hd-8) may also be mentioned.

[Chemistry 35]

The (m+n)-valent organic group having an aromatic ring in A of the above formula (e) may include an (m+n)-valent aromatic alkyl group having 6 to 30 carbon atoms, an (m+n)-valent organic group formed by directly or via a linking group an aromatic alkyl group having 6 to 30 carbon atoms, and an (m+n)-valent group having an aromatic heterocyclic ring. The above aromatic alkyl group may be benzene, naphthalene, etc. As for the aromatic heterocyclic ring, an aromatic heterocyclic ring represented by a pyridine ring in the structure exemplified for the above heterocyclic ring containing a nitrogen atom may be listed. The above linking group may include an alkylene group having 1 to 10 carbon atoms, -NR- (R is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms), or a group excluding one hydrogen atom from the above alkylene group, a divalent or trivalent cyclohexane ring, etc. In addition, any hydrogen atom of the above alkylene group may be substituted by an alkyl group having 1 to 6 carbon atoms, a fluorine atom or an organic group such as a trifluoromethyl group. Specific examples of the alkyl group having 1 to 5 carbon atoms in R and R' in the above formula (e) include the alkyl groups exemplified in _R1 to _R4 in the above formula (g).

Specific examples of the above formula (e) include compounds described in WO2010/074269 and compounds represented by any one of the following formulas (e-1) to (e-10).

[Chemistry 36]

The compounds exemplified above are examples of crosslinking compounds, but are not limited thereto. For example, the compounds disclosed in WO2015/060357, pages 53 [0105] to 55 [0116], etc. In addition, two or more crosslinking compounds may be combined.

In the liquid crystal alignment agent of the present invention, the content of the crosslinking compound is preferably 0.5 to 20 parts by weight relative to 100 parts by weight of the polymer component contained in the liquid crystal alignment agent. From the perspective of ideally obtaining the effect of the present invention, it is more preferably 1 to 15 parts by weight.

The above-mentioned adhesion aids, such as 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-ureidopropyl trimethoxysilane, 3-ureidopropyl triethoxysilane, N-phenyl-3-aminopropyl trimethoxysilane, N-phenyl-3-aminopropyl triethoxysilane, vinyl trimethoxysilane, vinyl triethoxysilane, 2-(3,4-epoxycyclohexyl)ethyl trimethoxysilane, 3-epoxypropyloxysilane, 3-Glycyrrhizic Acid, 3-Methacryloyloxypropyl Methyl Dimethoxysilane, 3-Methacryloyloxypropyl Trimethoxysilane ... Silane coupling agents include acyloxypropylmethyldiethoxysilane, 3-methacryloyloxypropyltriethoxysilane, 3-acryloyloxypropyltrimethoxysilane, tris[3-(trimethoxysilyl)propyl]isocyanurate, 3-butylpropylmethyldimethoxysilane, 3-butylpropyltrimethoxysilane, and 3-isocyanatepropyltriethoxysilane.

When using a silane coupling agent, in order to ideally obtain the effect of the present invention, the amount of the silane coupling agent is preferably 0.1 to 30 parts by mass, and more preferably 0.1 to 20 parts by mass, relative to 100 parts by mass of the polymer component contained in the liquid crystal alignment agent.

The compound for promoting the above-mentioned imidization is preferably a compound having a basic site (e.g., a primary amine group, an aliphatic heterocycle (e.g., a pyrrolidine skeleton), an aromatic heterocycle (e.g., an imidazole ring, an indole ring), or a guanidine group, etc.) (but excluding the above-mentioned cross-linking compound and a close-fitting aid.), or a compound that generates the above-mentioned basic site when calcined. More preferably, it is a compound that generates the above-mentioned basic site when calcined, and if specific examples are given, the compounds represented by the following formulas (B-1) to (B-17) can be listed. The content of the compound for promoting the imidization is preferably 2 mol or less, more preferably 1 mol or less, and even more preferably 0.5 mol or less, relative to 1 mol of the amide or amide ester site possessed by the polymer (A).

[Chemistry 37]

D represents an organic group that is released by heating, preferably Boc or Fmoc. When there are multiple Ds, the multiple Ds may be the same or different. In the liquid crystal alignment agent of the present invention, the solid component concentration (the ratio of the total mass of the components other than the solvent of the liquid crystal alignment agent to the total mass of the liquid crystal alignment agent) can be appropriately selected in consideration of viscosity, volatility, etc., and is preferably in the range of 1 to 10 mass%.

The range of the ideal solid component concentration varies depending on the method used when applying the liquid crystal alignment agent to the substrate. As described in step (1) below, the methods of applying the liquid crystal alignment agent to the substrate can be listed, for example: roller coating, spin coating, printing, inkjet, etc. When roller coating is used, the solid component concentration is preferably in the range of 4 to 10 mass %. When spin coating is used, the solid component concentration is preferably in the range of 1.5 to 4.5 mass %. When printing is used, the solid component concentration is preferably in the range of 3 to 9 mass %, so that the solution viscosity is preferably in the range of 12 to 50 mPa·s. When the inkjet method is used, the solid component concentration is in the range of 1 to 5 mass %, so that the solution viscosity is preferably in the range of 3 to 15 mPa·s. The temperature when preparing the polymer composition is preferably 10 to 50°C, and more preferably 20 to 30°C. <Liquid crystal alignment film> The liquid crystal alignment film of the present invention is obtained from the above-mentioned liquid crystal alignment agent. The liquid crystal alignment film of the present invention can be used in a horizontal alignment type or a vertical alignment type (VA type) liquid crystal alignment film, among which it is a liquid crystal alignment film suitable for a horizontal alignment type liquid crystal display element such as an IPS drive method or a FFS drive method. In addition, it is more suitable to use a liquid crystal alignment film for a photo-alignment treatment method. In addition, it can be effectively used in various technical applications, such as liquid crystal alignment films other than the above applications (liquid crystal alignment films for phase difference films, scanning antennas, liquid crystal array antennas, or liquid crystal alignment films for liquid crystal dimming elements of the through-scattering type), or other applications such as protective films (e.g. protective films for color filters), spacer films, interlayer insulation films, anti-reflection films, wiring coating films, anti-static films, motor insulation films (gate insulation films for flexible displays), etc.

The liquid crystal alignment film of the present invention can be manufactured by, for example, the following steps (1) to (3), preferably a method including steps (1) to (4). <Step (1): Step of applying the liquid crystal alignment agent on the substrate> The liquid crystal alignment agent of the present invention is applied to one side of the substrate having a patterned transparent conductive film by a suitable coating method such as roller coating, spin coating, printing, inkjet, etc. Here, the substrate is not particularly limited as long as it is a highly transparent substrate, and a glass substrate, a silicon nitride substrate, an acrylic substrate, a polycarbonate substrate, or other plastic substrates can be used together. In addition, if the reflective liquid crystal display element is a substrate with only one side, an opaque material such as a silicon wafer can also be used. In this case, the electrode can also use a material that reflects light such as aluminum. In addition, when manufacturing an IPS drive method or FFS drive method liquid crystal display element, a substrate with an electrode composed of a comb-shaped transparent conductive film or metal film and an opposing substrate without an electrode are used.

Methods for coating the liquid crystal alignment agent on the substrate and forming a film include screen printing, lithography, flexographic printing, inkjet, or spray coating. Among them, the method of coating and forming a film by inkjet is preferably used. <Step (2): Step of calcining the coated liquid crystal alignment agent> Step (2) is a step of calcining the liquid crystal alignment agent coated on the substrate and forming a film. After the liquid crystal alignment agent is coated on the substrate, the solvent can be evaporated by heating means such as a hot plate, a heat circulation oven, or an IR (infrared) oven, or thermal imidization of polyamide acid or polyamide ester can be performed. The drying and calcining steps after the liquid crystal alignment agent of the present invention is applied can be carried out at any temperature and time, and can also be carried out multiple times. The calcining temperature can be, for example, 40 to 180°C. Considering the viewpoint of shortening the treatment, it can be carried out at 40 to 150°C. The calcining time is not particularly limited, and can be 1 to 10 minutes, preferably 1 to 5 minutes. When thermal imidization of polyamine or polyamine ester is carried out, the calcining step can be carried out after the above calcining step, for example, at a temperature range of 150 to 300°C, preferably 150 to 250°C. The calcining time is not particularly limited, and can be 5 to 40 minutes, preferably 5 to 30 minutes.

If the film after calcination is too thin, the reliability of the liquid crystal display element will be reduced, so 5~300nm is more ideal, and 10~200nm is more ideal. <Step (3): Step of performing an alignment treatment on the film obtained in step (2)> Step (3) is a step of performing an alignment treatment on the film obtained in step (2) as needed. That is, in a horizontal alignment type liquid crystal display element such as an IPS drive mode or a FFS drive mode, the coating is treated to impart alignment capability. On the other hand, in a vertical alignment type liquid crystal display element such as a VA mode or a PSA mode, the formed coating can be used directly as a liquid crystal alignment film, but the coating can also be treated to impart alignment capability. The alignment treatment methods of the liquid crystal alignment film can be listed as friction treatment method and optical alignment treatment method, and the optical alignment treatment method is more ideal. The optical alignment treatment method can be listed as a method of irradiating the surface of the above-mentioned film-like object with radiation biased in a certain direction, and depending on the situation, it is preferably heated at a temperature of 150~250℃, and giving liquid crystal alignment (also known as liquid crystal alignment ability). The radiation can use ultraviolet light or visible light with a wavelength of 100~800nm. Among them, ultraviolet light with a wavelength of 100~400nm is preferred, and ultraviolet light with a wavelength of 200~400nm is more preferred.

The radiation dose is preferably 1-10,000 mJ/cm ² , more preferably 100-5,000 mJ/cm ² , more preferably 100-1,500 mJ/cm ² , particularly preferably 100-1,000 mJ/cm ² , and even more preferably 100-400 mJ/cm ^2. In the past, when using a liquid crystal alignment agent, the light irradiation dose for the alignment treatment was 100-5,000 mJ/cm ^2. However, even if the liquid crystal alignment agent of the present invention reduces the light irradiation dose for the alignment treatment, a liquid crystal alignment film with suppressed variation (non-uniformity) of the liquid crystal alignment property within the surface of the liquid crystal alignment film can still be obtained.

Furthermore, when irradiating the radiation, in order to improve the liquid crystal alignment, the substrate with the film may be heated at 50-250° C. The liquid crystal alignment film prepared in this way can align the liquid crystal molecules stably in a certain direction.

Furthermore, the liquid crystal alignment film irradiated with polarized radiation in the above method may be subjected to a contact treatment using water or a solvent, or the liquid crystal alignment film irradiated with radiation may be subjected to a heat treatment.

The solvent used in the above-mentioned contact treatment is not particularly limited as long as it can dissolve the decomposition products generated from the film due to radiation exposure. Specific examples include water, methanol, ethanol, 2-propanol, acetone, methyl ethyl ketone, 1-methoxy-2-propanol, 1-methoxy-2-propanol acetate, butyl celecoxib, ethyl lactate, methyl lactate, diacetone alcohol, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, propyl acetate, butyl acetate, cyclohexyl acetate, etc. Among them, considering the versatility and safety of the solvent, water, 2-propanol, 1-methoxy-2-propanol or ethyl lactate is preferred. More preferably, water, 1-methoxy-2-propanol or ethyl lactate is preferred. The solvent may be one or a combination of two or more. <Step (4): Performing a heat treatment at 50-300°C on the film that has been oriented in step (3)> The above-mentioned coating film irradiated with radiation may also be subjected to a heat treatment. The temperature of the heat treatment is preferably 50-300°C, and 120-250°C is more ideal. The time of the heat treatment is preferably 1-30 minutes. <Liquid crystal display element> The liquid crystal display element of the present invention has the liquid crystal alignment film of the present invention and can be manufactured in the following manner. Prepare two substrates on which the liquid crystal alignment film has been formed as obtained above, and arrange liquid crystal between the two oppositely arranged substrates. Specifically, the following two methods can be listed.

The first method is to firstly arrange two substrates facing each other with their respective liquid crystal alignment films facing each other with a gap (cell gap) between them. Then, the peripheries of the two substrates are bonded to each other using a sealant, and the cell gap separated by the substrate surface and the sealant is filled with a liquid crystal composition through an injection hole so that it contacts the film surface, and then the injection hole is sealed.

The second method is called 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 the liquid crystal alignment film has been formed, and then a liquid crystal composition is dripped at a predetermined number of locations on the surface of the liquid crystal alignment film. After that, the other substrate is attached in a manner that the liquid crystal alignment films face each other and the liquid crystal composition is pushed over the entire surface of the substrate to make it contact with the film surface. Then, ultraviolet light is irradiated to the entire surface of the substrate to cure the sealant.

When using either method, the liquid crystal composition is heated until it reaches an isotropic phase and then slowly cooled to room temperature to remove the ideal flow alignment during liquid crystal filling.

Furthermore, when the coating is subjected to rubbing treatment, two substrates are arranged opposite to each other in such a manner that the rubbing directions of the coatings form a predetermined angle with each other, for example, perpendicular or anti-parallel.

The sealant may be, for example, epoxy resin containing a hardener and aluminum oxide balls as spacers. Examples of the liquid crystal include nematic liquid crystal and lamellar liquid crystal, of which nematic liquid crystal is preferred.

The above-mentioned liquid crystal composition is not particularly limited, and various liquid crystal compositions containing at least one liquid crystal compound (liquid crystal molecule) and having a positive or negative dielectric anisotropy can be used. In addition, a liquid crystal composition having a positive dielectric anisotropy is also referred to as a positive liquid crystal, and a liquid crystal composition having a negative dielectric anisotropy is also referred to as a negative liquid crystal.

Examples of the liquid crystal composition include a liquid crystal composition presenting a nematic phase, a liquid crystal composition presenting a lamellar phase, and a liquid crystal composition presenting a cholesteric phase, among which the liquid crystal composition presenting a nematic phase is preferred.

The above-mentioned liquid crystal composition may also contain liquid crystal compounds having fluorine atoms, hydroxyl groups, amino groups, groups containing fluorine atoms (for example, trifluoromethyl groups), cyano groups, alkyl groups, alkoxy groups, alkenyl groups, isothiocyanate groups, heterocyclic groups, cycloalkanes, cycloalkenes, steroid skeletons, benzene rings, or naphthyl rings. It may also contain compounds having two or more rigid parts (mesogen skeletons) that exhibit liquid crystallinity in the molecule (for example, a bimesogen compound in which two rigid biphenyl structures or terphenyl structures are linked by an alkyl group).

In the above-mentioned liquid crystal composition, additives may be further added from the viewpoint of improving the orientation of the liquid crystal. Such additives may include photopolymerizable monomers such as compounds having polymerizable groups; optically active compounds (e.g., S-811 manufactured by Merck & Co., Ltd.); antioxidants; ultraviolet light absorbers; pigments; defoaming agents; polymerization initiators; or polymerization inhibitors, etc.

Examples of positive liquid crystals include ZLI-2293, ZLI-4792, MLC-2003, MLC-2041, MLC-3019, or MLC-7081 manufactured by Merck.

Negative liquid crystal, such as MLC-6608, MLC-6609, MLC-6610, or MLC-7026-100 manufactured by Merck.

Examples of the liquid crystal containing a compound having a polymerizable group include MLC-3023 manufactured by Merck.

Furthermore, a liquid crystal display element can be obtained by attaching a polarizing plate to the outer surface of the liquid crystal cell as needed. Examples of polarizing plates attached to the outer surface of the liquid crystal cell include: a polarizing plate made of a polarizing film called "H film" obtained by sandwiching a cellulose acetate protective film and extending and aligning polyvinyl alcohol to absorb iodine, or a polarizing plate composed of the H film itself.

The IPS substrate is a comb-tooth electrode substrate used in the IPS method (mode), comprising: a substrate; a plurality of linear electrodes formed on the substrate and arranged in a comb-tooth shape; and a liquid crystal alignment film formed on the substrate in a manner of covering the linear electrodes.

In addition, the FFS substrate is a comb-tooth electrode substrate of the FFS method (mode), which has: a substrate; a surface electrode formed on the substrate; an insulating film formed on the surface electrode; a plurality of linear electrodes formed on the insulating film and arranged in a comb-tooth shape; and a liquid crystal alignment film formed on the insulating film in a manner of covering the linear electrodes.

FIG. 1 is a schematic cross-sectional view showing an example of an IPS mode transverse electric field liquid crystal display element having a liquid crystal alignment film obtained using the liquid crystal alignment agent of the present invention.

In the transverse electric field liquid crystal display element 1 illustrated in FIG1 , a liquid crystal 3 is sandwiched between a comb-tooth electrode substrate 2 having a liquid crystal alignment film 2c and an opposing substrate 4 having a liquid crystal alignment film 4a. The comb-tooth electrode substrate 2 has: a substrate 2a; a plurality of linear electrodes 2b formed on the substrate 2a and arranged in a comb shape; and a liquid crystal alignment film 2c formed on the substrate 2a in a manner of covering the linear electrodes 2b. The opposing substrate 4 has a substrate 4b and a liquid crystal alignment film 4a formed on the substrate 4b. The liquid crystal alignment film 2c is the liquid crystal alignment film of the present invention. The liquid crystal alignment film 4c is also the liquid crystal alignment film of the present invention.

In the transverse electric field liquid crystal display element 1 of FIG. 1 , when a voltage is applied to the linear electrodes 2 b , an electric field is generated between the linear electrodes 2 b as indicated by electric field lines L.

FIG. 2 is a schematic cross-sectional view showing an example of a FFS mode transverse electric field liquid crystal display element having a liquid crystal alignment film obtained from the liquid crystal alignment agent of the present invention.

In the transverse electric field liquid crystal display element 1 illustrated in FIG2 , liquid crystal 3 is sandwiched between a comb-tooth electrode substrate 2 having a liquid crystal alignment film 2h and an opposing substrate 4 having a liquid crystal alignment film 4a. The comb-tooth electrode substrate 2 comprises: a substrate 2d; a surface electrode 2e formed on the substrate 2d; an insulating film 2f formed on the surface electrode 2e; and a plurality of linear electrodes 2g formed on the insulating film 2f and arranged in a comb shape; and a liquid crystal alignment film 2h formed on the insulating film 2f in a manner of covering the linear electrodes 2g. The opposing substrate 4 comprises: a substrate 4b and a liquid crystal alignment film 4a formed on the substrate 4b. The liquid crystal alignment film 2h is the liquid crystal alignment film of the present invention. The liquid crystal alignment film 4a is also the liquid crystal alignment film of the present invention.

In the transverse electric field liquid crystal display element 1 of FIG. 2 , if a voltage is applied to the surface electrode 2e and the linear electrode 2g, an electric field will be generated between the surface electrode 2e and the linear electrode 2g as shown by the electric field lines L. [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 following compounds and the methods for measuring the properties are as follows. (Organic solvent) NMP: N-methyl-2-pyrrolidone BCS: Ethylene glycol monobutyl ether (Tetracarboxylic dianhydride) CA-1~CA-2: Each is a compound represented by the following formula (CA-1)~(CA-2) (Diamine) DA-1~DA-8: Each is a compound represented by the following formula (DA-1)~(DA-8)

[Chemistry 38]

<Viscosity measurement> Use E-type viscometer TVE-22H (manufactured by Toki Sangyo Co., Ltd.), sample volume 1.1mL, use conical rotor TE-1 (1°34', R24), and measure at 25°C. <Molecular weight measurement> Measured with the following room temperature GPC (gel permeation chromatography) device, Mn and Mw were calculated based on polyethylene glycol and polyethylene oxide conversion values.

GPC apparatus: GPC-101 (manufactured by Showa Denko Co., Ltd.), column: GPC KD-803, GPC KD-805 (manufactured by Showa Denko Co., Ltd.) in series, column temperature: 50°C, solvent: N,N-dimethylformamide (additives: lithium bromide monohydrate (LiBr・H ₂ O) 30 mmol/L, anhydrous phosphoric acid (orthophosphoric acid) 30 mmol/L, tetrahydrofuran (THF) 10 mL/L), flow rate: 1.0 mL/min. Standard samples for calibration curve preparation: TSK standard polyethylene oxide (molecular weight: about 900,000, about 150,000, about 100,000 and about 30,000) (manufactured by Tosoh Co., Ltd.) and polyethylene glycol (molecular weight: about 12,000, about 4,000 and about 1,000) (Polymer Laboratory Corporation). [Synthesis of polymer] <Synthesis Example 1> DA-1 (1.08 g, 8.86 mmol), DA-2 (2.16 g, 8.86 mmol), DA-3 (1.89 g, 5.91 mmol), DA-4 (2.35 g, 5.90 mmol), CA-1 (6.22 g, 27.8 mmol) and NMP (100 g) were added to a 100 mL four-necked flask equipped with a stirring device and a nitrogen inlet tube, and stirred at 40°C for 20 hours to obtain a solution of polyamide (A-1) with a solid content concentration of 12 mass% (viscosity: 372 mPa・s). The Mn of this polyamide is 12,042 and the Mw is 39,532. <Synthesis Example 2> DA-5 (1.21 g, 8.86 mmol), DA-2 (2.16 g, 8.86 mmol), DA-3 (1.89 g, 5.91 mmol), DA-4 (2.35 g, 5.90 mmol), CA-1 (6.22 g, 27.8 mmol) and NMP (101 g) were added to a 100 mL four-necked flask equipped with a stirring device and a nitrogen inlet tube, and stirred at 40°C for 20 hours to obtain a solution of polyamide (A-2) with a solid content concentration of 12 mass % (viscosity: 367 mPa・s). The Mn of this polyamide is 12,001 and the Mw is 40,211. <Synthesis Example 3> DA-8 (1.21 g, 8.86 mmol), DA-2 (2.16 g, 8.86 mmol), DA-3 (1.89 g, 5.91 mmol), DA-4 (2.35 g, 5.90 mmol), CA-1 (6.22 g, 27.8 mmol) and NMP (101 g) were added to a 100 mL four-necked flask equipped with a stirring device and a nitrogen inlet tube, and stirred at 40°C for 20 hours to obtain a solution of polyamide (A-3) with a solid content concentration of 12 mass % (viscosity: 367 mPa・s). The Mn of this polyamide is 12,001 and the Mw is 40,211. <Synthesis Example 4> DA-6 (1.28 g, 11.8 mmol), DA-7 (5.29 g, 17.7 mmol), CA-2 (5.44 g, 27.8 mmol) and NMP (88.1 g) were added to a 100 mL four-necked flask equipped with a stirring device and a nitrogen inlet tube, and stirred at room temperature for 3 hours to obtain a solution of polyamide (B-1) with a solid content concentration of 12 mass % (viscosity: 130 mPa・s). The Mn of this polyamide is 10,100 and the Mw is 37,822.

The types and amounts of the tetracarboxylic acid derivative components and diamine components used in Synthesis Examples 1 to 4 are summarized in Table 1. In Table 1, the values in parentheses represent the amount (in moles) of the monomers used relative to 100 moles of the total monomers in each component.

[Table 1] Synthesis Example Polyamine Tetracarboxylic acid components Diamine component Specific diamine Other diamines 1 A-1 CA-1 (100) DA-1 (30) DA-2 (30) DA-3 (20) DA-4 (20) - 2 A-2 CA-1 (100) - DA-2 (30) DA-3 (20) DA-4 (20) DA-5 (30) 3 A-3 CA-1 (100) DA-8 (30) DA-2 (30) DA-3 (20) DA-4 (20) - 4 B-1 CA-2 (100) - DA-6 (40) DA-7 (60) - -

<Preparation of liquid crystal alignment agent> (Example 1) Add the polymer solution (B-1) (7.50 g), NMP (8.50 g) and BCS (9.00 g) to the above polymer solution (A-1) (5.00 g), stir at room temperature for 2 hours to obtain a liquid crystal alignment agent (V-1). (Comparative Example 1) Add the polymer solution (B-1) (7.50 g), NMP (8.50 g) and BCS (9.00 g) to the above polymer solution (A-2) (5.00 g), stir at room temperature for 2 hours to obtain a liquid crystal alignment agent (RV-1).

The specifications of the liquid crystal alignment agents obtained in the above-mentioned Example 1 and Comparative Example 1 are shown in Table 2. The values in parentheses in the polymer components represent the amount (parts by mass) of each polymer component introduced relative to 100 parts by mass of the total polymer components.

[Table 2] Liquid crystal alignment agent Polymer composition Solid content [mass %] Solvent composition [mass %] NMP BCS Embodiment 1 V-1 A-1 (40) B-1 (60) 5 65 30 Comparison Example 1 RV-1 A-2 (40) B-1 (60) 5 65 30

[Fabrication of FFS-driven liquid crystal cell] (Example 2-1) Fabricate a liquid crystal cell having the structure of a FFS mode liquid crystal display element.

First, prepare a substrate with electrodes. The substrate is a glass substrate with a rectangular shape of 30mm×50mm and a thickness of 0.7mm. An ITO electrode with a full-plate pattern is formed on the substrate as the first layer constituting the common electrode. A SiN (silicon nitride) film formed by CVD (chemical evaporation) is formed as the second layer on the first layer of the common electrode. The second layer of SiN film has a thickness of 300nm and acts as an interlayer insulating film. On the second layer of SiN film, a comb-shaped pixel electrode formed by patterning the ITO film as the third layer is arranged, forming two pixels, the first pixel and the second pixel, and the size of each pixel is 10mm in length and 5mm in width. The substrate with electrodes has a structure in which a common electrode on the first layer and a pixel electrode on the third layer are insulated by a SiN film on the second layer.

The pixel electrode of the third layer has a comb shape in which a plurality of electrode lines with a width of 3 μm are arranged in parallel at intervals of 6 μm and the central portion is bent at an internal angle of 160°. One pixel is formed by a plurality of electrode lines and has a first region and a second region bounded by a line connecting the bent portions.

Then, the liquid crystal alignment agent (V-1) obtained in the above-mentioned Example 1 is filtered through a filter with an aperture of 1.0μm, and then coated on the above-mentioned electrode support substrate (hereinafter referred to as the electrode substrate) and the glass substrate with a columnar spacer with a height of 4μm and an ITO film formed on the back (hereinafter referred to as the opposite substrate) by spin coating. After drying on a hot plate at 80°C for 2 minutes, it is calcined in a hot air circulation oven at 230°C for 20 minutes to form a coating with a film thickness of 100nm. The coated surface is irradiated with polarized ultraviolet light through a 254nm bandpass filter and polarized light, and then calcined in an IR oven at 230°C for 0 minutes to perform alignment treatment to obtain a substrate with a liquid crystal alignment film. The irradiation amount is shown in the following Table 3. Furthermore, the liquid crystal alignment film formed on the electrode substrate was subjected to an alignment treatment so that the direction of dividing the inner angle of the pixel bend into equal parts was perpendicular to the alignment direction of the liquid crystal. The alignment film formed on the opposite substrate was subjected to an alignment treatment so that the alignment direction of the liquid crystal on the electrode substrate was consistent with the alignment direction of the liquid crystal on the opposite substrate when the liquid crystal cell was made. The two substrates were grouped together, and a sealant (XN-1500T manufactured by Mitsui Chemicals, Inc.) was printed on the substrates using a dispenser, and another substrate was bonded so that the alignment direction of each liquid crystal alignment film was 0° and faced each other. After that, the bonded substrates were pressed together and heated in a hot air circulation oven at 150°C for 60 minutes to harden the sealant and make a cell. In this empty cell, negative liquid crystal MLC-7026-100 (Merck) is injected by reduced pressure injection method, and the injection port is sealed to obtain an FFS-driven liquid crystal cell. Afterwards, the obtained liquid crystal cell is heated at 120°C for 1 hour and placed at 23°C overnight. Visual observation shows that the liquid crystal in the liquid crystal cell is uniformly aligned. (Comparative Example 2-1) The liquid crystal alignment agent is changed to the liquid crystal alignment agent (RV-1) obtained in Comparative Example 1, and a liquid crystal cell is prepared according to the same procedure as Example (2-1). Visual observation shows that the liquid crystal in the liquid crystal cell is uniformly aligned. [Evaluation of film hardness] (Example 3-1) The liquid crystal alignment agent (V-1) obtained in Example 1 was applied to an ITO substrate by spin coating. After drying on a hot plate at 80°C for 2 minutes, it was calcined in an IR oven at 230°C for 30 minutes to form a coating with a thickness of 100 nm. The coating surface was irradiated with 400 mJ/ ^cm2 of linearly polarized ultraviolet light with an extinction ratio of 26:1 through a polarizing plate to perform an alignment treatment, and then calcined in an IR oven at 230°C for 30 minutes to obtain a substrate with a liquid crystal alignment film. Afterwards, the liquid crystal alignment film was rubbed and aligned using a spun cloth (HY-5318, manufactured by Hyperflex) (roller diameter: 120 mm, roller speed: 1000 rpm, moving speed: 20 mm/sec, push length: 0.5 mm), and the haze value (turbidity) of the film was evaluated using a haze meter (HZ-V3, manufactured by SUGA Testing Instrument Co., Ltd.). The smaller the haze value, the less thinned the film is, which means that the film hardness is high. Based on the evaluation criteria, a haze value of less than 0.10 was rated as "○", and a haze value of more than 0.10 was rated as "×". The results are shown in Table 3. (Comparative Example 3-1) The film hardness was evaluated in the same manner as in Example (3-1) except that the liquid crystal alignment agent was changed to the liquid crystal alignment agent (RV-1) obtained in Comparative Example 1. The results are shown in Table 3.

[table 3] Liquid crystal alignment agent UV exposure (J/cm ² ) Film hardness Example 3-1 V-1 0.4 0.07 (○) Comparative Example 3-1 RV-1 0.4 0.10 (×)

As can be seen from Table 3 above, the liquid crystal alignment film obtained by using a liquid crystal alignment agent containing a specific diamine has a better film hardness than the liquid crystal alignment film obtained by using a liquid crystal alignment agent containing no specific diamine. [Industrial Applicability]

By using the liquid crystal alignment agent of the present invention, a polyimide liquid crystal alignment film can be obtained, which is a liquid crystal alignment film with high mechanical strength even if substituted cyclobutane tetracarboxylic dianhydride or its derivatives are used as raw materials. Therefore, it can be expected to be used in liquid crystal display elements requiring high display quality, especially liquid crystal display elements of IPS drive mode and FFS drive mode. In addition, these elements are also useful in liquid crystal displays for display purposes, dimming windows for controlling light transmission and blocking, light gates, etc.

1: Transverse electric field liquid crystal display element 2: Comb electrode substrate 2a: Substrate 2b: Linear electrode 2c: Liquid crystal alignment film 2d: Substrate 2e: Surface electrode 2f: Insulating film 2g: Linear electrode 2h: Liquid crystal alignment film 3: Liquid crystal 4: Counter substrate 4a: Liquid crystal alignment film 4b: Substrate L: Electric line

FIG1 is a schematic cross-sectional view of one example of a transverse electric field liquid crystal display element having a liquid crystal alignment film obtained by the liquid crystal alignment agent of the present invention. FIG2 is a schematic cross-sectional view of another example of a transverse electric field liquid crystal display element having a liquid crystal alignment film obtained by the liquid crystal alignment agent of the present invention.

1: Transverse electric field liquid crystal display element

2: Comb electrode substrate

2a: Base material

2b: Linear electrode

2c: Liquid crystal alignment film

3: Liquid crystal

4: Opposite substrate

4a: Liquid crystal alignment film

4b: Base material

L: Power lines

Claims (17)

A liquid crystal alignment agent, characterized in that it contains a polymer (A), wherein the polymer (A) is at least one selected from the group consisting of a polyimide precursor having a repeating unit (a1) represented by the following formula (1) and a polyimide which is an imide compound of the polyimide precursor. R and Z each independently represent a hydrogen atom or a monovalent organic group. The liquid crystal alignment agent of claim 1, wherein the polymer (A) is at least one polymer selected from the group consisting of a polyimide precursor having a repeating unit (a2) represented by the following formula (2) and a polyimide which is an imide compound of the polyimide precursor, In formula (2), R and Z have the same meanings as in formula (1), and _Y2 represents a divalent organic group represented by the following formula (O), In formula (O), Ar each independently represents a benzene ring, a biphenyl structure, or a naphthyl ring, any hydrogen atom on the Ar ring may be substituted by a halogen atom or a monovalent organic group, _Q2 represents -( _CH2 ) _n- (n is 2 to 18), or a group in which a part of -( _CH2 ) _n- is substituted by any one of -O-, -C(=O)- and -OC(=O)-, and * represents an atomic bond. The liquid crystal alignment agent of claim 2, wherein the divalent organic group represented by the formula (O) is a divalent organic group represented by any one of the following formulas (o-1) to (o-15), In formulas (o-1) to (o-14), * represents an atomic bond, and in formulas (o-14) to (o-15), two m's are independent of each other. The liquid crystal alignment agent of claim 1, wherein the polymer (A) is at least one polymer selected from the group consisting of a polyimide precursor further comprising at least one selected from the group consisting of a repeating unit (a2') represented by the following formula (2') and a repeating unit (a3) represented by the following formula (3) and a polyimide which is an imide compound of the polyimide precursor, In formula (2') and (3), X _2' and X ₃ represent a tetravalent organic group, Y _2' represents a divalent organic group represented by the following formula (O2), Y ₃ represents a divalent organic group having a group "-N(D)-, D represents a carbamate protective group" in the molecule and excluding D, and having a carbon number of 6 to 30. R and Z have the same meaning as in the case of the above formula (1). In formula (O2), m is an integer of 0 to 2, Ar _2' represents an unsubstituted or substituted benzene ring, but when m is 0, Ar _2' represents an unsubstituted benzene ring, when m is 1 or 2, Ar _2' each independently represents an unsubstituted benzene ring, or a benzene ring in which any hydrogen atom on the benzene ring is substituted by a halogen atom or a monovalent organic group, Q _2' represents a single bond or -O-, * represents an atomic bond, and when multiple Ar _2' and Q _2' exist, they may be the same or different. The liquid crystal alignment agent of claim 4, wherein the divalent organic group represented by the formula (O2) is a divalent organic group represented by any one of the following formulas (o2-1) to (o2-12), In formulas (o2-1) to (o2-12), * represents an atomic bond. The liquid crystal alignment agent of claim 1, wherein in the polymer (A), the total content of the repeating unit (a1) and the imide structural unit of the repeating unit (a1) is 10-95 mol% of all the repeating units. The liquid crystal alignment agent of claim 2, wherein in the polymer (A), the total content of the repeating unit (a2) and the imide structural unit of the repeating unit (a2) is 10-90 mol% of all the repeating units. The liquid crystal alignment agent of claim 2, wherein in the polymer (A), the total content of the repeating unit (a1), the repeating unit (a2), the repeating unit (a2') represented by the following formula (2'), and the imidized structural units thereof is greater than 30 mol% of all the repeating units, In formula (2'), X _2' represents a tetravalent organic group, Y _2' represents a divalent organic group represented by the following formula (O2), and R and Z have the same meanings as in the above formula (1). In formula (O2), m is an integer of 0 to 2, Ar _2' represents an unsubstituted or substituted benzene ring, but when m is 0, Ar _2' represents an unsubstituted benzene ring, when m is 1 or 2, Ar _2' each independently represents an unsubstituted benzene ring, or a benzene ring in which any hydrogen atom on the benzene ring is substituted by a halogen atom or a monovalent organic group, Q _2' represents a single bond or -O-, * represents an atomic bond, and when multiple Ar _2' and Q _2' exist, they may be the same or different. The liquid crystal alignment agent of claim 1, wherein the liquid crystal alignment agent further comprises a polymer (B) having no repeating unit (a1) in the molecule, wherein the polymer (B) is a polymer having at least one repeating unit selected from the group consisting of a repeating unit (b1) represented by the following formula (5) and an imidized structural unit of the repeating unit (b1), In formula (5), X ₅ is a tetravalent organic group, Y ₅ is a divalent organic group, and R and Z are the same as R and Z in formula (1). The liquid crystal alignment agent of any one of claims 1 to 9 is used in a liquid crystal alignment film for photo-alignment treatment. A liquid crystal alignment film is obtained from the liquid crystal alignment agent of any one of claims 1 to 9. A liquid crystal display element comprises a liquid crystal alignment film as claimed in claim 11. A method for manufacturing a liquid crystal alignment film for a liquid crystal display element comprises the following steps (1) to (3), Step (1): applying a liquid crystal alignment agent as described in any one of claims 1 to 9 on a substrate, Step (2): calcining the applied liquid crystal alignment agent, Step (3): performing alignment treatment on the film obtained in step (2) as needed. A method for manufacturing a liquid crystal alignment film as claimed in claim 13, wherein the alignment treatment is a photo-alignment treatment. The method for manufacturing a liquid crystal alignment film of claim 14, wherein the radiation exposure in the photo-alignment treatment is 100-1,500 mJ/cm ² . The method for manufacturing a liquid crystal alignment film as claimed in claim 13 further includes a step (4) of heating the film that has been aligned in step (3) at a temperature of 50-300°C. A method for manufacturing a liquid crystal alignment film as claimed in claim 13, wherein the liquid crystal display element is an IPS driven liquid crystal display element or an FFS driven liquid crystal display element.