JP7622744B2 - Liquid crystal alignment agent, liquid crystal alignment film, and liquid crystal display element - Google Patents

Description

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

Liquid crystal display elements are used in a wide range of applications, from small applications such as mobile phones and smartphones to relatively large applications such as televisions and monitors. Liquid crystal display elements are generally constructed by arranging a pair of electrode substrates facing each other with a certain gap (several μm) between them and sealing liquid crystal between the electrode substrates. Display on the liquid crystal display element is performed by applying a voltage between the transparent conductive films that make up the electrodes of the electrode substrates. These liquid crystal display elements have a liquid crystal alignment film that is essential for controlling the alignment state of the liquid crystal molecules.

Meanwhile, various driving methods have been developed for liquid crystal display elements, which differ in electrode structure, physical properties of liquid crystal molecules used, etc. For example, various modes such as TN (Twisted Nematic) type, STN (Super Twisted Nematic) type, VA (Vertical Alignment) type, IPS (In-Plane Switching) type, FFS (Fringe Field Switching) type, etc. are known.
Among these, VA (vertical alignment) type liquid crystal display elements have a wide viewing angle, a fast response speed, high contrast, and do not require rubbing treatment in the production process, and are therefore widely used, especially for televisions and monitors, for which there is a high demand for larger displays.

International Publication No. 2008/117615 JP 2008-76950 A

By the way, the above-mentioned transparent conductive film in the liquid crystal display element is usually formed of a composition (ITO) in which indium oxide is the main component and several percent of tin oxide is doped therein, and the refractive index of the film is different from that of the liquid crystal alignment film and has a high value. Therefore, when light from a display light source is transmitted through the electrode substrate, the light is reflected at the interface between the transparent conductive film and the liquid crystal alignment film in each electrode substrate. As a result, the light transmittance of the electrode substrate cannot be sufficiently obtained, leading to a problem of a decrease in display brightness.
In particular, ultra-high definition panels such as 4K and 8K have been developed in recent years. However, in these panels, the occupancy rate of black matrix (BM) and TFT (Thin Film Transistor) increases, resulting in a decrease in the aperture ratio of the panel. Therefore, it is important to improve the transmittance of the display area.

Therefore, the inventors of the present invention have investigated various materials for increasing the refractive index of the liquid crystal alignment film, from the viewpoint that the above-mentioned problems can be eliminated by reducing the difference between the refractive index of the transparent conductive film and the refractive index of the liquid crystal alignment film. Specifically, in order to increase the refractive index of the liquid crystal alignment film, various types of polymers to be contained in the liquid crystal alignment agent that forms the liquid crystal alignment film were explored.

As a result, by selecting a specific polymer, it was possible to obtain a liquid crystal alignment film with a refractive index close to that of the transparent conductive film. However, on the other hand, it became clear that polymers that form liquid crystal alignment films with high refractive indexes do not have very good solubility in the solvent components of the liquid crystal alignment agent, and therefore tend to be inferior in terms of the storage stability of the liquid crystal alignment agent and the coatability (printability) on the substrate, leaving room for further improvement.

In view of the above circumstances, the object of the present invention is to provide a liquid crystal alignment agent that has good solubility of the components contained in the liquid crystal alignment agent and is capable of forming a liquid crystal alignment film having a high refractive index, a liquid crystal alignment film obtained from the liquid crystal alignment agent, and a liquid crystal display element having the liquid crystal alignment film.

（Ａｒはフェニレン基を表し、Ｑは少なくとも１つのナフタレン環を含む２価の有機基を表し、Ｑと２つの酸素原子のそれぞれとは、上記少なくとも１つのナフタレン環を構成するベンゼン環上で結合し、一方の酸素原子と結合するベンゼン環と、他方の酸素原子と結合するベンゼン環とは、異なる。上記フェニレン基上の任意の水素原子は、炭素数１～３のアルキル基、炭素数１～３のアルコキシ基、炭素数１～３のフッ素含有アルキル基、炭素数１～３のフッ素含有アルコキシ基及びフッ素原子からなる群から選ばれる少なくとも１種で置換されていてもよい。） As a result of intensive research into achieving the above object, the present inventors have found that a liquid crystal aligning agent containing a polymer having a specific structure is effective in achieving the above object, and have completed the present invention.
The present invention relates to a liquid crystal aligning agent, characterized by containing a polymer (P) containing at least one selected from the group consisting of a polyimide precursor and a polyimide obtained by using a diamine component containing diamine (1) (hereinafter also referred to as a specific diamine) represented by the following formula (1), a liquid crystal alignment film obtained from the liquid crystal aligning agent, and a liquid crystal display element having the liquid crystal alignment film.

(Ar represents a phenylene group, Q represents a divalent organic group containing at least one naphthalene ring, Q and each of the two oxygen atoms are bonded on a benzene ring constituting the at least one naphthalene ring, and the benzene ring bonded to one oxygen atom is different from the benzene ring bonded to the other oxygen atom. Any hydrogen atom on the phenylene group may be substituted with at least one selected from the group consisting of an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a fluorine-containing alkyl group having 1 to 3 carbon atoms, a fluorine-containing alkoxy group having 1 to 3 carbon atoms, and a fluorine atom.)

According to the present invention, a liquid crystal aligning agent is obtained which has good solubility of the components contained therein and can form a liquid crystal alignment film having a high refractive index. Since the liquid crystal alignment film formed from such a liquid crystal aligning agent has a high refractive index, the difference between the refractive index of the transparent conductive film in a liquid crystal display element and the refractive index of the liquid crystal alignment film can be reduced, and a liquid crystal display element with excellent display quality can be obtained.
Although the mechanism by which the above-mentioned effects of the present invention are obtained is not entirely clear, the following is believed to be one of the reasons: In other words, in the polymer of the present invention, the naphthalene ring is arranged at the center of the diamine molecule, not at the bonding position of the amino group, which is thought to reduce the packing property of the polymer and improve the solubility, and also to increase the refractive index of the liquid crystal alignment film obtained by introducing the naphthalene ring.

Hereinafter, the liquid crystal alignment agent of the present invention, the liquid crystal alignment film obtained from the liquid crystal alignment agent, and the liquid crystal display element having the liquid crystal alignment film will be described in detail. However, the explanation of the constituent elements described below is an example of one embodiment of the present invention, and the present invention is not limited to these contents.
In the following explanation, Boc represents a tert-butoxycarbonyl group, and examples of the "halogen atom" include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

(Liquid crystal alignment agent)
The liquid crystal aligning agent of the present invention contains a polymer (P) and further contains other components as required.

(Polymer (P))
The polymer (P) contains at least one selected from the group consisting of polyimide precursors obtained using a diamine component and polyimides.
The polymer (P) is at least one selected from the group consisting of polyimide precursors and polyimides, and may be one component or two or more components.

（上記式（１）において、Ａｒ、Ｑは、それぞれ上記で定義したとおりである。） (Diamine component)
The diamine component contains a diamine (1) represented by the following formula (1).

(In the above formula (1), Ar and Q are as defined above.)

（Ａ_１及びＡ_２は、それぞれ独立して、置換基を有していてもよいナフタレン環である。Ｘ_１及びＸ_２は、それぞれ独立して、単結合、酸素原子又は硫黄原子である。Ｙは、炭素数１～８のアルキレン基、又は炭素数１～８のアルキレン基の炭素－炭素結合間に酸素原子若しくは硫黄原子を含む２価の有機基である。ｍは０～２の整数であり、ｎは、０又は１の整数である。＊は結合手を表す。） Among these, from the viewpoint of obtaining the effects of the present invention, it is preferable that Q has 10 to 40 carbon atoms, and it is more preferable that Q is a divalent organic group having 10 to 40 carbon atoms and represented by the following formula (f).

( _A1 and _A2 are each independently a naphthalene ring which may have a substituent. _X1 and _X2 are each independently a single bond, an oxygen atom or a sulfur atom. Y is an alkylene group having 1 to 8 carbon atoms, or a divalent organic group containing an oxygen atom or a sulfur atom between the carbon-carbon bonds of an alkylene group having 1 to 8 carbon atoms. m is an integer of 0 to 2, and n is an integer of 0 or 1. * represents a bond.)

The naphthalene ring may have a substituent. Examples of the substituent that the naphthalene ring may have include an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, and a halogen atom. _X1 and _X2 are preferably an oxygen atom.

Preferred specific examples of the diamine (1) represented by the above formula (1) include the following formulas (d-1) to (d-2).

When the polymer (P) contained in the liquid crystal alignment agent of the present invention is applied to a liquid crystal alignment agent for a liquid crystal display element of a TN mode, STN mode, VA mode, PSA mode, or SC-PVA mode, it is preferable to contain, as a constituent, a diamine (s) having at least one selected from the group consisting of partial structures represented by the following formulas (S1) to (S3) in addition to the diamine represented by the above formula (1). In the polymer (P), the diamine (s) may be at least one constituent selected from the group consisting of polyimide precursors and polyimides containing the diamine (1) as a constituent, or at least one constituent selected from the group consisting of polyimide precursors and polyimides different from the at least one selected from the group consisting of polyimide precursors and polyimides containing the diamine (1) as a constituent.

In formula (S1), X ¹ and X ² each independently represent a single bond, -(CH ₂ ) _a - (a is an integer of 1 to 15), -CONH-, -NHCO-, -CON(CH ₃ )-, -N(CH ₃ )CO-, -NH-, -O-, -COO-, -OCO-, -((CH ₂ ) _a1 -A ₁ ) _m1 -, or -(A ₁ -(CH ₂ ) _a1 ) _m1 - (a1 is an integer of 1 to 15, A ₁ represents an oxygen atom, -COO-, or -OCO-, and m1 is an integer of 1 to 2. When m1 is 2, each of the multiple a1's is independent and each of the multiple A _1's is independent). G ¹ and G ² each independently represent a divalent cyclic group selected from a divalent aromatic group having 6 to 12 carbon atoms and a divalent alicyclic group having 3 to 8 carbon atoms. Any hydrogen atom on the cyclic group may be substituted with at least one selected from the group consisting of an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a fluorine-containing alkyl group having 1 to 3 carbon atoms, a fluorine-containing alkoxy group having 1 to 3 carbon atoms, and a fluorine atom. m and n each independently represent an integer of 0 to 3, and the sum of m and n is 1 to 6. From the viewpoint of improving the liquid crystal alignment property, the sum of m and n is preferably 2 to 6, and more preferably 2 to 4. ^{R 1} represents 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, and any hydrogen atom forming R ¹ may be substituted with a fluorine atom.
Examples of the divalent cyclic group in G ¹ and G ² include a cyclopropylene group, a cyclohexylene group, and a phenylene group. Any hydrogen atom on these cyclic groups may be substituted with an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a fluorine-containing alkyl group having 1 to 3 carbon atoms, a fluorine-containing alkoxy group having 1 to 3 carbon atoms, or a fluorine atom.

In formula (S2), ^X3 represents a single bond, -CONH-, -NHCO-, -CON( _CH3 )-, -N( _CH3 )CO-, -NH-, -O-, _-CH2O- , -COO- or -OCO-. ^R2 represents an alkyl group having 1 to 20 carbon atoms or an alkoxyalkyl group having 2 to 20 carbon atoms, and any hydrogen atom forming ^R2 may be substituted with a fluorine atom.
From the viewpoint of improving the liquid crystal alignment property, ^R2 is preferably an alkyl group having 3 to 20 carbon atoms or an alkoxyalkyl group having 2 to 20 carbon atoms.

In formula (S3), ^X4 represents -CONH-, -NHCO-, -O-, -COO-, -OCO-, -(( _CH2 ) _a1 - _A1 ) _m1- , or -( _A1- ( _CH2 ) _a1 ) _m1- [a1 is an integer of 1 to 15, _A1 represents an oxygen atom, -COO-, or -OCO-, and m1 is an integer of 1 to 2. When m1 is 2, a1 are each independent and _A1 are each independent]. ^R3 represents a structure having a steroid skeleton. In addition, ^R3 is preferably a structure containing a cholestanyl group, a cholesteryl group, or a lanostannyl group.

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

In the above formula, ^R1 represents 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. ^Xp represents -( _CH2 ) _a- (a is an integer of 1 to 15), -CONH-, -NHCO-, -CON( _CH3 )-, -NH-, -O-, _-CH2O- , _-CH2OCO- , -COO-, or -OCO-. _A1 represents an oxygen atom or -COO-* (wherein the bond marked with "*" is bonded to ( _CH2 ) _a2 ), _A2 represents an oxygen atom or *-COO- (wherein the bond marked with "*" is bonded to ( _CH2 ) _a2 ), a1 and a3 each independently represent an integer of 0 or 1, a2 represents an integer of 1 to 10, and Cy represents a 1,4-cyclohexylene group or a 1,4-phenylene group.

A specific preferred example of the above formula (S3) is the following formula [S3-x]. In formula [S3-x], X represents formula [X1], formula [X2] or -CH ₂ -O-, Col represents formula [Col1], formula [Col2] or formula [Col3], and G represents formula [G1], formula [G2], formula [G3] or formula [G4]. In the formula, "Me" represents a methyl group. * represents a bond.

Preferred diamines (s) having the partial structures represented by the above formulae (S1) to (S3) are diamines having the partial structures represented by the above formulae (S1) to (S3) and at least one benzene ring. Examples of diamines (s) include diamines represented by the following formulae (d1) and (d2).

In formulae (d1) and (d2), Y represents a side chain structure represented by any of formulae (S1) to (S3) above. _{Moreover , ​ ​ ​ ​ ​ ​ ​ ​ ​} -, -CO-(CH ₂ ) _m -CO-, -NH-(CH ₂ ) _m -, -NH-(CH ₂ ) _m -NH-, -SO ₂ -(CH ₂ ) _m -, -SO ₂ -(CH ₂ ) _m -SO ₂ -, -CONH-(CH ₂ ) _m -, -CONH-(CH ₂ ) _m -NHCO-, or -COO-(CH ₂ ) _m represents —OCO—, and m is an integer of 1 to 8. In the above formula (d2), the two Ys may be the same or different.

（ｎは１～２０の整数である。） Preferred specific examples of the diamine of the above formula (d1) include the following formulas (d1-1) to (d1-18).

(n is an integer from 1 to 20.)

The diamine represented by the above formula (d2) may have a structure selected from the group consisting of the following formulas (d2-1) to (d2-6).

In the above formula, X ^p1 to X ^p8 represent -(CH ₂ ) _a - (a is an integer of 1 to 15), -CONH-, -NHCO-, -CON(CH ₃ )-, -NH-, -O-, -CH ₂ O-, -CH ₂ OCO-, -COO-, or -OCO-. X ^s1 to X ^s4 each independently represent -O-, -COO-, or -OCO-. _{X a} to X _f each independently represent a single bond, -O-, -NH-, or -O-(CH ₂ ) _m -O- (m is an integer of 1 to 8). ^{R 1a} to R ^1h each independently represent an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, or an alkoxyalkyl group having 2 to 20 carbon atoms.

(Production of Polymer (P))
The polymer (P) contained in the liquid crystal alignment agent of the present invention may be composed of one or more polyimide precursors and polyimide which is an imidized product of the polyimide precursor. Here, the polyimide precursor is a polymer which can obtain a polyimide by imidizing a polyamic acid, a polyamic acid ester, etc. More preferred specific embodiments of the polymer (P) are listed below, but the present invention is not limited thereto.

at least one polymer (hereinafter also referred to as a copolymer) selected from the group consisting of a polyimide precursor obtained by using a diamine component containing the diamine (1) and the diamine (s), and a polyimide which is an imidized product of the polyimide precursor;
A mixture (hereinafter also referred to as a polymer blend) of at least one polymer (p-1) selected from the group consisting of a polyimide precursor obtained by using a diamine component containing the diamine (1) and a polyimide which is an imidized product of the polyimide precursor, and at least one polymer (p-2) selected from the group consisting of a polyimide precursor obtained by using a diamine component containing the diamine (s) and a polyimide which is an imidized product of the polyimide precursor, and the like.
The above copolymers or polymer blends may be used alone or in combination.

The polyamic acid (P), which is a polyimide precursor of the polymer (P), can be obtained by a polymerization reaction between a diamine component containing the diamine (1) (preferably a diamine component containing a diamine (s) in addition to the diamine (1)) and a tetracarboxylic acid component.
In this case, the amount of diamine (1) used is preferably from 1 to 100 mol %, more preferably from 1 to 99 mol %, and even more preferably from 5 to 95 mol %, based on the diamine component to be reacted with the tetracarboxylic acid component.

When diamine (s) is used in addition to the above diamine (1), the amount of diamine (s) used is preferably 1 to 99 mol %, more preferably 1 to 95 mol %, based on the diamine component to be reacted with the tetracarboxylic acid component.

The diamine component used in the production of the polyamic acid (P) may contain diamines other than the diamine (1) and the diamine (s) (hereinafter, these are also referred to as other diamines). Examples of other diamines are given below, but the present invention is not limited to these.

（式（３ｂ－１）中、Ａ^１は単結合、－ＣＨ_２－、－Ｃ_２Ｈ_４－、－Ｃ（ＣＨ_３）_２－、－ＣＦ_２－、－Ｃ（ＣＦ_３）_２－、－Ｏ－、－ＣＯ－、－ＮＨ－、－Ｎ（ＣＨ_３）－、－ＣＯＮＨ－、－ＮＨＣＯ－、－ＣＨ_２Ｏ－、－ＯＣＨ_２－、－ＣＯＯ－、－ＯＣＯ－、－ＣＯＮ（ＣＨ_３）－又は－Ｎ（ＣＨ_３）ＣＯ－を示し、ｍ１及びｍ２はそれぞれ独立して、０～４の整数を示し、かつｍ１＋ｍ２は１～４の整数を示す。式（３ｂ－２）中、ｍ３及びｍ４はそれぞれ独立して、１～５の整数を示す。式（３ｂ－３）中、Ａ^２は炭素数１～５の直鎖又は分岐アルキル基を示し、ｍ５は１～５の整数を示す。式（３ｂ－４）中、Ａ^３及びＡ^４はそれぞれ独立して、単結合、－ＣＨ_２－、－Ｃ_２Ｈ_４－、－Ｃ（ＣＨ_３）_２－、－ＣＦ_２－、－Ｃ（ＣＦ_３）_２－、－Ｏ－、－ＣＯ－、－ＮＨ－、－Ｎ（ＣＨ_３）－、－ＣＯＮＨ－、－ＮＨＣＯ－、－ＣＨ_２Ｏ－、－ＯＣＨ_２－、－ＣＯＯ－、－ＯＣＯ－、－ＣＯＮ（ＣＨ_３）－又は－Ｎ（ＣＨ_３）ＣＯ－を示し、ｍ６は１～４の整数を示す。）

（ｎは１～６の整数である。）

Diamines having a carboxy group, such as p-phenylenediamine, m-phenylenediamine, 4-(2-(methylamino)ethyl)aniline, 2,4-diaminobenzoic acid, 2,5-diaminobenzoic acid, 3,5-diaminobenzoic acid, and diamine compounds represented by the following formulas (3b-1) to (3b-4); 4,4'-diaminodiphenylmethane, 3,3'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether; 1,2-bis(4-aminophenyl)ethane, 1,3-bis(4-aminophenyl)propane, 1,4-bis(4-aminophenyl)butane, 1,4-bis(4-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1, 2-bis(4-aminophenoxy)ethane, 1,2-bis(4-amino-2-methylphenoxy)ethane, 1,3-bis(4-aminophenoxy)propane, 1,4-bis(4-aminophenoxy)butane, 1,5-bis(4-aminophenoxy)pentane, 1,6-bis(4-aminophenoxy)hexane, 4-(2-(4-aminophenoxy)ethoxy)-3-fluoroaniline, di(2-(4-aminophenoxy)ethyl)ether, 4-amino-4'-(2-(4-aminophenoxy)ethoxy)biphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminobiphenyl, 4,4'-diamino-2,2'-bis(trifluoromethyl)biphenyl, 1,4- diaminonaphthalene, 1,5-diaminonaphthalene, 2,6-diaminonaphthalene, 2,7-diaminonaphthalene, diamines represented by the following formulas (nh-1) to (nh-6), diamines having a urea bond such as 2,2'-bis[4-(4-aminophenoxy)phenyl]propane, 2,2'-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, 2,2'-bis(4-aminophenyl)propane, and 1,3-bis(4-aminophenethyl)urea, diamines having a photopolymerizable group at the terminal such as 2-(2,4-diaminophenoxy)ethyl methacrylate and 2,4-diamino-N,N-diallylaniline, diamines having a radical initiation function such as those represented by the following formulas (R1) to (R5), 4,4'-diaminobenzyl esters, etc. diamines having a photosensitizing function that exhibits a sensitizing effect upon irradiation with light, such as benzophenone, 3,3'-diaminobenzophenone, and 9,9-bis(4-aminophenyl)fluorene; 2,6-diaminopyridine, 3,4-diaminopyridine, 2,4-diaminopyrimidine, 3,6-diaminocarbazole, N-methyl-3,6-diaminocarbazole; diamines having a heterocycle such as those of the following formulae (z-1) to (z-18); diamines having a diphenylamine skeleton such as those of the following formulae (Dp-1) to (Dp-9); diamines having a group "-N(Boc)" such as those of the following formulae (5-1) to (5-10); diamines having an oxazoline structure such as those of the following formulae (Ox-1) to (Ox-2); and diamines described in WO 2016/125870.

(In formula (3b-1), A ¹ represents a single bond, —CH ₂ —, —C ₂ H ₄ —, —C(CH ₃ ) ₂ —, —CF ₂ —, —C(CF ₃ ) ₂ —, —O—, —CO—, —NH—, —N(CH ₃ )—, —CONH—, —NHCO—, —CH ₂ O—, —OCH ₂ —, —COO—, —OCO—, —CON(CH ₃ )— or —N(CH ₃ )CO—; m1 and m2 each independently represent an integer of 0 to 4, and m1+m2 represents an integer of 1 to 4; in formula (3b-2), m3 and m4 each independently represent an integer of 1 to 5; in formula (3b-3), A In formula (3b-4), A ³ and A ⁴ each independently represent a single bond, —CH ₂ —, —C ₂ H ₄ —, —C(CH ₃ ) ₂ —, —CF ₂ —, —C(CF ₃ ) ^{2 —} , _—O— , —CO—, —NH—, —N(CH 3 )—, —CONH—, —NHCO—, —CH ₂ O—, _{—OCH 2} —, —COO—, —OCO—, —CON(CH ₃ )— or —N(CH ₃ )CO—, and m6 represents an integer from 1 to 4.

(n is an integer from 1 to 6.)

Among these, as the other diamines, from the viewpoint of suitably obtaining the effects of the present invention, p-phenylenediamine, 3,5-diaminobenzoic acid, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, 4,4'-diaminobenzophenone, 2,2'-dimethyl-4,4'-diaminobiphenyl, 2-(2,4-diaminophenoxy)ethyl methacrylate, 2,4-diamino-N,N-diallylaniline, diamines represented by the above formulas (R1) to (R5), diamines represented by the above formulas (z-1) to (z-18), diamines represented by the above formulas (5-1) to (5-10), and diamines represented by the above formulas (Ox-1) to (Ox-2) are preferred.
When other diamines are used in addition to the diamine (1), the amount of the other diamines used is preferably 1 to 99 mol %, more preferably 5 to 95 mol %, based on the total diamine components used.
When other diamines are used in addition to the diamine (1) and diamine (s), the amount of diamine (s) used is preferably 98 mol % or less, more preferably 94 mol % or less, based on the diamine components to be reacted with the tetracarboxylic acid component.

The amount of diamine represented by the above formulas (5-1) to (5-10) used is preferably 5 to 40 mol %, and more preferably 10 to 40 mol %, of the total diamine components used in the production of polyamic acid (P).

In liquid crystal display elements using the PSA method or SC-PVA mode, in order to increase the response speed, one or more of 4,4'-diaminobenzophenone, 3,3'-diaminobenzophenone, diamines having a photopolymerizable group at the end, diamines represented by the above formulas (R1) to (R5), and diamines represented by the above formulas (z-1) to (z-18) can be used when producing polyamic acid (P), and the amount used is preferably 1 to 40 mol%, more preferably 5 to 40 mol%, of the total diamine components used in the production of polyamic acid (P).

(Tetracarboxylic acid component)
In producing the polyamic acid (P), the tetracarboxylic acid component to be reacted with the diamine component may be not only a tetracarboxylic acid dianhydride but also a derivative of a tetracarboxylic acid dianhydride, such as a tetracarboxylic acid, a tetracarboxylic acid dihalide, a tetracarboxylic acid dialkyl ester, or a tetracarboxylic acid dialkyl ester dihalide.

The tetracarboxylic acid dianhydride or derivative thereof may be an aromatic, aliphatic, or alicyclic tetracarboxylic acid dianhydride, or a derivative thereof. Here, the aromatic tetracarboxylic acid dianhydride is an acid dianhydride obtained by intramolecular dehydration of four carboxy groups, including at least one carboxy group bonded to an aromatic ring. The aliphatic tetracarboxylic acid dianhydride is an acid dianhydride obtained by intramolecular dehydration of four carboxy groups bonded to a chain hydrocarbon structure. However, it is not necessary for the structure to be composed only of a chain hydrocarbon structure, and it may have an alicyclic structure or an aromatic ring structure as part of it.

Alicyclic tetracarboxylic dianhydrides are acid dianhydrides obtained by intramolecular dehydration of four carboxy groups, including at least one carboxy group bonded to an alicyclic structure. However, none of these four carboxy groups are bonded to an aromatic ring. Furthermore, they do not have to be composed of only alicyclic structures, and may have a chain hydrocarbon structure or an aromatic ring structure as part of them.

但し、式（Ｔ）中、Ｘは、下記（ｘ－１）～（ｘ－１３）からなる群から選ばれる構造を表す。 Among them, the tetracarboxylic dianhydride or derivative thereof is preferably one represented by the following formula (T): That is, the polymer (P) preferably contains a tetracarboxylic acid component containing the tetracarboxylic dianhydride represented by the formula (T) as a constituent component.

In the formula (T), X represents a structure selected from the group consisting of the following (x-1) to (x-13):

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. R ⁵ and R ⁶ each independently represent a hydrogen atom or a methyl group. j and k are integers of 0 or 1, and A ₁ and A ₂ each independently represent a single bond, an ether (-O-), a carbonyl (-CO-), an ester (-COO- or -OCO-), a phenylene group, a sulfonyl group (-SO ₂ -), or an amide group (-CONH- or -NHCO-). *1 is a bond bonded to one acid anhydride group, and *2 is a bond bonded to the other acid anhydride group. In formula (x-13), the two A ₂ may be the same or different from each other.

More preferred examples of the above formula (x-1) include the following formulae (X1-1) to (X1-6). In the formulae, * represents a bond.

Preferred specific examples of the above formulae (x-12) and (x-13) include the following formulae (x-14) to (x-29), in which * represents a bond.

Preferred specific examples of the tetracarboxylic dianhydride or derivative thereof represented by the above formula (T) include those in which X is selected from the above formulas (x-1) to (x-7) and (x-11) to (x-13).

The proportion of the tetracarboxylic dianhydride represented by the above formula (T) or a derivative thereof used is preferably 1 mol % or more, more preferably 5 mol % or more, and even more preferably 10 mol % or more, based on 1 mol of the total tetracarboxylic acid components used.
The tetracarboxylic dianhydride and its derivatives used in the production of the polyamic acid (P) may contain a tetracarboxylic dianhydride or its derivative other than that of the above formula (T).

The polyamic acid (P) is produced by reacting the diamine component and the tetracarboxylic acid component in a solvent (condensation polymerization). The solvent is not particularly limited as long as the produced polymer is soluble in the solvent.
Specific examples of the solvent include N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, γ-butyrolactone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethylsulfoxide, 1,3-dimethyl-2-imidazolidinone, etc. In addition, when the polymer has high solubility in the solvent, methyl ethyl ketone, cyclohexanone, cyclopentanone, 4-hydroxy-4-methyl-2-pentanone, or the solvents represented by the following formulas [D-1] to [D-3] can be used.

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

These solvents may be used alone or in combination. Furthermore, even if the solvent does not dissolve the polymer, it may be mixed with the above-mentioned solvent to the extent that the produced polymer does not precipitate.
When the diamine component and the tetracarboxylic acid component are reacted in a solvent, the reaction can be carried out at any concentration, but the total amount of the diamine component and the tetracarboxylic acid component relative to the reaction solution is preferably 1 to 50% by mass, more preferably 5 to 30% by mass. The reaction can be carried out at a high concentration in the early stage, and then the solvent can be added.
In the reaction, the ratio of the total number of moles of the diamine components to the total number of moles of the tetracarboxylic acid components is preferably 0.8 to 1.2. As in a normal polycondensation reaction, the closer this molar ratio is to 1.0, the higher the molecular weight of the specific polymer produced.

The polyamic acid ester, which is a polyimide precursor, can be obtained by known methods such as, for example, [I] a method of reacting the polyamic acid obtained by the above synthesis reaction 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.

[Polyimide]
The polyimide contained in the liquid crystal aligning agent of the present invention is a polyimide obtained by ring-closing the above-mentioned polyimide precursor. In the polyimide, the ring-closing rate of the amic acid group (also called the imidization rate) does not necessarily need to be 100%, and can be arbitrarily adjusted according to the application or purpose.

Methods for obtaining polyimide by imidizing a polyimide precursor include thermal imidization, in which a solution of the polyimide precursor is heated as is, and catalytic imidization, in which a catalyst is added to a solution of the polyimide precursor. When thermally imidizing a polyimide precursor in a solution, the temperature is 100 to 400°C, preferably 120 to 250°C, and it is preferable to carry out the process while removing water generated by the imidization reaction from the system.

Catalytic imidization of polyimide precursors can be carried out by adding a basic catalyst and an acid anhydride to a solution of the polyimide precursor and stirring at -20 to 250°C, preferably 0 to 180°C. The amount of the basic catalyst is 0.5 to 30 molar times, preferably 2 to 20 molar times, the amount of the acid anhydride is 1 to 50 molar times, preferably 3 to 30 molar times, the amount of the acid anhydride is 1 to 50 molar times, preferably 3 to 30 molar times, the amount of the acid anhydride. Examples of basic catalysts include pyridine, triethylamine, trimethylamine, tributylamine, trioctylamine, etc., and pyridine is preferred because it has a suitable basicity for promoting the reaction. Examples of acid anhydrides include acetic anhydride, trimellitic anhydride, pyromellitic anhydride, etc., and acetic anhydride is preferred because it makes purification after the reaction easy. The imidization rate by catalytic imidization can be controlled by adjusting the amount of catalyst, reaction temperature, and reaction time.

When recovering the polyimide produced from the reaction solution of the imidization of the polyimide precursor, the reaction solution may be poured into a solvent to cause precipitation. Examples of solvents used for precipitation include methanol, ethanol, isopropyl alcohol, acetone, hexane, butyl cellosolve, heptane, methyl ethyl ketone, methyl isobutyl ketone, toluene, benzene, and water. The polymer precipitated by pouring into the solvent can be recovered by filtration, and then dried at room temperature or by heating under normal or reduced pressure. In addition, the polymer precipitated and recovered can be redissolved in a solvent and the reprecipitation and recovery operation repeated 2 to 10 times to reduce impurities in the polymer. Examples of solvents used in this case include alcohols and ketones and hydrocarbons, and it is preferable to use three or more solvents selected from these because the efficiency of purification is further improved.

The polystyrene-equivalent weight average molecular weight (Mw) of the polyimide precursor and polyimide measured by gel permeation chromatography (GPC) is preferably 5,000 to 1,000,000, and more preferably 10,000 to 150,000. The molecular weight distribution (Mw/Mn), expressed as the ratio of Mw to the polystyrene-equivalent number average molecular weight (Mn) measured by GPC, is preferably 15 or less, and more preferably 10 or less. Having the molecular weight within this range ensures good alignment of the liquid crystal display element.

<End-capping agent>
In synthesizing the polymer (P) in the present invention, a terminal-capping type polymer may be synthesized by using a suitable terminal-capping agent together with the above-mentioned tetracarboxylic acid component and diamine component. The terminal-capping type polymer has the effect of improving the film hardness of the liquid crystal alignment film obtained by coating and improving the adhesion property between the sealant and the liquid crystal alignment film.
Examples of the terminal of the polymer (P) in the present invention include an amino group, a carboxy group, an acid anhydride group, an isocyanate group, or a derivative thereof. The above terminal can be obtained by a conventional condensation reaction or by blocking the terminal with the following terminal blocking agent.

Examples of the terminal blocking agent include acid monoanhydrides such as acetic anhydride, maleic anhydride, nadic anhydride, phthalic anhydride, itaconic anhydride, cyclohexanedicarboxylic anhydride, 3-hydroxyphthalic anhydride, trimellitic anhydride, compounds represented by the following formulas (m-1) to (m-6), 3-(3-trimethoxysilyl)propyl)-3,4-dihydrofuran-2,5-dione, 4,5,6,7-tetrafluoroisobenzofuran-1,3-dione, and 4-ethynylphthalic anhydride;
Examples of the dicarbonate diester compounds include di-tert-butyl dicarbonate and diallyl dicarbonate; chlorocarbonyl compounds include acryloyl chloride, methacryloyl chloride and nicotinic acid chloride; monoamine compounds include 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 and n-octylamine; and monoisocyanate compounds include ethyl isocyanate, phenyl isocyanate and naphthyl isocyanate.

The proportion of the end-capping agent used is preferably 0.01 to 20 molar parts, and more preferably 0.01 to 10 molar parts, per 100 molar parts of the total diamine components used.

The content ratio of polymer (P) in the liquid crystal alignment agent of the present invention is preferably 30 parts by mass or more, more preferably 30 to 100 parts by mass, and even more preferably 50 to 100 parts by mass, per 100 parts by mass of the total of the polymers contained in the liquid crystal alignment agent.

(Other ingredients)
The liquid crystal aligning agent of the present invention is, for example, a liquid composition obtained by dispersing or dissolving the polymer (P) and other components used as necessary, preferably in a suitable solvent.

In the liquid crystal aligning agent of the present invention, for example, for the purpose of improving electrical properties, vertical alignment properties, and solution properties, other polymers (hereinafter also referred to as other polymers) may be contained in addition to the polymer (P).
The content of the other polymers is preferably 90 parts by mass or less, more preferably 10 to 90 parts by mass, and even more preferably 20 to 80 parts by mass, based on 100 parts by mass of the total of the polymers contained in the liquid crystal alignment agent.

The other polymers are not particularly limited, and examples of the main skeleton include polysiloxane, polyester, polyamide, polyurea, polyorganosiloxane, cellulose derivatives, polyacetal, polystyrene derivatives, poly(styrene-phenylmaleimide) derivatives, and poly(meth)acrylate. Of these, at least one selected from the group consisting of polyamide, polyurea, polyorganosiloxane, poly(meth)acrylate, and polyester is preferable. Note that two or more of the other polymers may be used in combination.

The liquid crystal aligning agent of the present invention may contain other components as necessary. Examples of the components include at least one compound selected from the group consisting of crosslinkable compounds having at least one substituent selected from an epoxy group, an isocyanate group, an oxetane group, a cyclocarbonate group, a blocked isocyanate group, a hydroxy group, and an alkoxy group, and crosslinkable compounds having a polymerizable unsaturated group, a functional silane compound, a metal chelate compound, a curing accelerator, a surfactant, an antioxidant, a sensitizer, a preservative, and a compound for adjusting the dielectric constant or electrical resistance of the liquid crystal alignment film.
Preferable specific examples of the crosslinkable compound include compounds represented by the following formulas (CL-1) to (CL-11).

Compounds for adjusting the dielectric constant and electrical resistance of the liquid crystal alignment film include monoamines having a nitrogen-containing aromatic heterocycle, such as 3-picolylamine. When using a monoamine having a nitrogen-containing aromatic heterocycle, it is preferable that the amount is 0.1 to 30 parts by mass, and more preferably 0.1 to 20 parts by mass, per 100 parts by mass of the polymer component contained in the liquid crystal alignment agent.

Specific examples of preferred functional silane compounds include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyldiethoxymethylsilane, 2-aminopropyltrimethoxysilane, 2-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-ureidopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, Examples of the functional silane compound include 3-glycidoxypropyl trimethoxysilane, 3-glycidoxypropyl methyl diethoxysilane, 3-glycidoxypropyl triethoxysilane, p-styryl trimethoxysilane, 3-methacryloxypropyl methyl dimethoxysilane, 3-methacryloxypropyl trimethoxysilane, 3-methacryloxypropyl methyl diethoxysilane, 3-methacryloxypropyl triethoxysilane, 3-acryloxypropyl trimethoxysilane, tris-(trimethoxysilylpropyl)isocyanurate, 3-mercaptopropyl methyl dimethoxysilane, 3-mercaptopropyl trimethoxysilane, and 3-isocyanate propyl triethoxysilane. When a functional silane compound is used, it is preferably 0.1 to 30 parts by mass, 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 organic solvent contained in the liquid crystal alignment agent is not particularly limited as long as it dissolves the polymer component uniformly. Specific examples include N,N-dimethylformamide, N,N-dimethylacetamide, N,N-dimethyllactamide, 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-dimethylpropanamide, 3-butoxy-N,N-dimethylpropanamide, 3-methylpropanol ... Examples of the good solvent include propanamide, 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 (collectively referred to as "good solvent"). Among these, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, 3-methoxy-N,N-dimethylpropanamide, 3-butoxy-N,N-dimethylpropanamide, or γ-butyrolactone are preferred. The content of the good solvent is preferably 20 to 99% by mass, more preferably 20 to 90% by mass, and particularly preferably 30 to 80% by mass of the total solvent contained in the liquid crystal alignment agent.

In addition, it is preferable to use a mixed solvent containing the above-mentioned solvent and a solvent (also called a poor solvent) that improves the coatability and surface smoothness of the coating film when applying the liquid crystal alignment agent. Specific examples of organic solvents to be used in combination are listed below, but are not limited to these.

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, ethylene carbonate, ethylene glycol monobutyl ether, ethylene glycol monoisoamyl ether, ethylene glycol monohexyl ether, propylene glycol monobutyl ether, 1-(2-butoxyethoxy)-2-propanol 1-propanol, 2-(2-butoxyethoxy)-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 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 acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, ethyl 3-methoxypropionate, propyl 3-methoxypropionate, butyl 3-methoxypropionate, n-butyl lactate, isoamyl lactate, diethylene glycol monoethyl ether, diisobutyl ketone (2,6-dimethyl-4-heptanone), and the like.

Of these, 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.
The content of the poor solvent is preferably 1 to 80% by mass, more preferably 10 to 80% by mass, and particularly preferably 20 to 70% by mass, of the total solvent contained in the liquid crystal alignment agent. The type and content of the poor solvent are appropriately selected depending on the coating device, coating conditions, coating environment, etc. of the liquid crystal alignment agent.

Preferred solvent combinations of good and poor solvents include N-methyl-2-pyrrolidone and ethylene glycol monobutyl ether, N-methyl-2-pyrrolidone, γ-butyrolactone and ethylene glycol monobutyl ether, N-methyl-2-pyrrolidone, 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 diisobutyl ketone, N-methyl-2-pyrrolidone and ethyl 3-ethoxypropionate, N-ethyl-2-pyrrolidone and ethyl 3-ethoxypropionate, 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,N-dimethyl lactamide and diethylene glycol diethyl ether, N-methyl-2-pyrrolidone and γ-butyrolactone and 4-hydroxy-4-methyl-2-pentanone and 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 and propylene glycol monobutyl ether, N-methyl-2-pyrrolidone and 4-hydroxy-4-methyl-2-pentanone and diisobutyl ketone, N -methyl-2-pyrrolidone, 4-hydroxy-4-methyl-2-pentanone, and dipropylene glycol monomethyl ether, N-methyl-2-pyrrolidone, 4-hydroxy-4-methyl-2-pentanone, and propylene glycol monobutyl ether, N-methyl-2-pyrrolidone, 4-hydroxy-4-methyl-2-pentanone, and propylene glycol diacetate, γ-butyrolactone, 4-hydroxy-4-methyl-2-pentanone, and diisobutyl ketone, γ-butyrolactone, 4-hydroxy-4-methyl-2-pentanone, and propylene glycol diacetate, N-methyl-2-pyrrolidone, γ-butyrolactone, propylene glycol monobutyl ether, and diisobutyl ketone, N-methyl-2-pyrrolidone, γ-butyrolactone, propylene glycol monobutyl ether, and diisopropyl ether, N-methyl-2-pyrrolidone Examples of the alkyl ethers include 2-pyrrolidone, γ-butyrolactone, propylene glycol monobutyl ether, and diisobutyl carbinol, N-methyl-2-pyrrolidone, γ-butyrolactone, and dipropylene glycol dimethyl ether, N-methyl-2-pyrrolidone, propylene glycol monobutyl ether, and dipropylene glycol dimethyl ether, N-ethyl-2-pyrrolidone, propylene glycol monobutyl ether, and dipropylene glycol monomethyl ether, N-ethyl-2-pyrrolidone, propylene glycol monobutyl ether, and propylene glycol diacetate, N-ethyl-2-pyrrolidone, propylene glycol monobutyl ether, and diisobutyl ketone, N-ethyl-2-pyrrolidone, γ-butyrolactone, and diisobutyl ketone, and N-ethyl-2-pyrrolidone, N,N-dimethyl lactamide, and diisobutyl ketone.

The solid content concentration in the liquid crystal alignment agent (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) is appropriately selected taking into consideration the viscosity, volatility, etc., but is preferably in the range of 1 to 10 mass%. The particularly preferred range of solid content concentration varies depending on the method used to apply the liquid crystal alignment agent to the substrate. For example, in the case of the spinner method, the solid content concentration is particularly preferably in the range of 1.5 to 4.5 mass%. In the case of the printing method, it is particularly preferable to set the solid content concentration in the range of 3 to 9 mass%, thereby setting the solution viscosity in the range of 12 to 50 mPa·s. In the case of the inkjet method, it is particularly preferable to set the solid content concentration in the range of 1 to 5 mass%, thereby setting the solution viscosity in the range of 3 to 15 mPa·s.

(Liquid crystal alignment film/Liquid crystal display element)
The liquid crystal alignment film of the present invention is obtained from the above liquid crystal aligning agent. The liquid crystal alignment film of the present invention can be used as a horizontal alignment type or vertical alignment type liquid crystal alignment film, and is particularly suitable for a vertical alignment type liquid crystal display element such as a VA mode or a PSA mode described later. The liquid crystal display element of the present invention is provided with the above liquid crystal alignment film.
The liquid crystal display element of the present invention comprises the liquid crystal alignment film of the present invention.
An example of the method for producing a liquid crystal display element of the present invention includes steps (A), (B), and (C).
Step (A): A step of applying the liquid crystal alignment agent of the present invention onto a pair of substrates having conductive films to form a coating film. Step (B): A step of forming a liquid crystal cell by arranging the coating films so as to face each other with a layer of liquid crystal molecules interposed therebetween. Step (C): A step of irradiating the liquid crystal cell with light while a voltage is applied between the conductive films of the pair of substrates.

The liquid crystal display element of the present invention can be produced, for example, by a method including the following steps (1) to (3) or (1) to (4).
(1) Step of applying liquid crystal alignment agent to substrate The liquid crystal alignment agent of the present invention is applied to one side of a substrate provided with a patterned transparent conductive film by an appropriate application method such as a roll coater method, a spin coat method, a printing method, an inkjet method, etc. Here, the substrate is not particularly limited as long as it is a highly transparent substrate, and plastic substrates such as acrylic substrates and polycarbonate substrates can be used in addition to glass substrates and silicon nitride substrates. In addition, in a reflective liquid crystal display element, an opaque material such as a silicon wafer can be used for only one substrate, and in this case, a light-reflecting material such as aluminum can be used for the electrode.

(2) Step of baking the coating film After applying the liquid crystal alignment agent, a pre-heating (pre-bake) is preferably performed first for the purpose of preventing dripping of the applied alignment agent. The pre-bake temperature is preferably 30 to 200°C, more preferably 40 to 150°C, and particularly preferably 40 to 100°C. The pre-bake time is preferably 0.25 to 10 minutes, more preferably 0.5 to 5 minutes. Then, in order to evaporate the solvent, a further heating (post-bake) step is preferably performed. The post-bake temperature is preferably 80 to 300°C, more preferably 120 to 250°C. The post-bake time is preferably 5 to 200 minutes, more preferably 10 to 100 minutes. The film thickness of the film thus formed is preferably 5 to 300 nm, more preferably 10 to 200 nm.

The coating film formed in the above step (1) can be used as it is as a liquid crystal alignment film, but the coating film may be subjected to an alignment ability imparting treatment. Examples of the alignment ability imparting treatment include a rubbing treatment in which the coating film is rubbed in a certain direction with a roll wrapped with a cloth made of fibers such as nylon, rayon, or cotton, and a photoalignment treatment in which the coating film is irradiated with polarized or non-polarized radiation.

In the photo-alignment treatment, the radiation irradiated to the coating film can be, for example, ultraviolet light and visible light containing light with a wavelength of 150 to 800 nm. When the radiation is polarized, it may be linearly polarized or partially polarized. Furthermore, when the radiation used is linearly polarized or partially polarized, the irradiation may be performed from a direction perpendicular to the substrate surface, from an oblique direction, or a combination of these. When irradiating with unpolarized radiation, the direction of irradiation is oblique.

(3) Step of forming a liquid crystal layer (3-1) In the case of a VA-type liquid crystal display element Two substrates on which a liquid crystal alignment film is formed as described above are prepared, and liquid crystal is placed between the two substrates arranged opposite each other. Specifically, the following two methods can be mentioned. The first method is a conventionally known method. First, the two substrates are arranged opposite each other with a gap (cell gap) between them so that the respective liquid crystal alignment films face each other. Next, the peripheries of the two substrates are bonded together using a sealant, and a liquid crystal composition is injected and filled into the substrate surfaces and the cell gap partitioned by the sealant so as to come into contact with the film surface, and then the injection hole is sealed.

The second method is a method called the ODF (One Drop Fill) method. For example, a UV-curable sealant is applied to a predetermined location on one of the two substrates on which a liquid crystal alignment film is formed, and a liquid crystal composition is dropped at several predetermined locations on the liquid crystal alignment film surface. The other substrate is then attached so that the liquid crystal alignment film faces the other substrate, and the liquid crystal composition is spread over the entire surface of the substrate and brought into contact with the film surface. Next, the entire surface of the substrate is irradiated with UV light to cure the sealant. In either method, it is desirable to remove the flow alignment that occurs during liquid crystal filling by heating the substrate to a temperature at which the liquid crystal composition used assumes an isotropic phase and then slowly cooling to room temperature.

The liquid crystal aligning agent of the present invention is also preferably used for a liquid crystal display element (hereinafter, also referred to as a PSA type liquid crystal display element) which has a liquid crystal layer between a pair of substrates provided with electrodes, and is manufactured through a process of disposing a liquid crystal composition containing a polymerizable compound which is polymerized by at least one of active energy rays and heat between the pair of substrates, and polymerizing the polymerizable compound by at least one of irradiation with active energy rays and heating while applying a voltage between the electrodes.
The liquid crystal aligning agent of the present invention may also be used for a liquid crystal display element (hereinafter, also referred to as an SC-PVA mode type liquid crystal display element) which has a liquid crystal layer between a pair of substrates having electrodes, and is manufactured through a process of disposing a liquid crystal alignment film containing a polymerizable group that is polymerized by at least one of active energy rays and heat between the pair of substrates, and applying a voltage between the electrodes.

(3-2) In the case of producing a PSA type liquid crystal display element, the same procedure as in (3-1) above is followed except that a liquid crystal composition containing a polymerizable compound is injected or dropped. Examples of the polymerizable compound include those represented by the following formulae (M-1) to (M-7).

(3-3) In the case of producing an SC-PVA mode type liquid crystal display element, a method of producing a liquid crystal display element through a step of irradiating ultraviolet light described later may be adopted after the same procedure as in (3-1) above. According to this method, a liquid crystal display element having excellent response speed can be obtained with a small amount of light irradiation, as in the case of producing the PSA type liquid crystal display element. The compound having a polymerizable group may be a compound having one or more polymerizable unsaturated groups in the molecule, such as acrylate groups or methacrylate groups, as represented by the above formulas (M-1) to (M-7), and the content thereof is preferably 0.1 to 30 parts by mass, more preferably 1 to 20 parts by mass, relative to 100 parts by mass of all polymer components. In addition, the polymerizable group may be possessed by a polymer used for a liquid crystal alignment agent, and an example of such a polymer includes a polymer obtained by using a diamine component containing a diamine having the above photopolymerizable group at its terminal in a reaction.

(4) Step of irradiating ultraviolet light The liquid crystal cell is irradiated with light while a voltage is applied between the conductive films of the pair of substrates obtained in (3-2) or (3-3) above. The voltage applied here can be, for example, 5 to 50 V DC or AC. The light to be irradiated can be, for example, ultraviolet light and visible light containing light with a wavelength of 150 to 800 nm, but ultraviolet light containing light with a wavelength of 300 to 400 nm is preferred. The light source for the irradiation light can be, for example, a low-pressure mercury lamp, a high-pressure mercury lamp, a deuterium lamp, a metal halide lamp, an argon resonance lamp, a xenon lamp, an excimer laser, or the like. The amount of light irradiation is preferably 1,000 to 200,000 J/m ² , and more preferably 1,000 to 100,000 J/m ² .

A liquid crystal display element can be obtained by attaching a polarizing plate to the outer surface of the liquid crystal cell. Examples of polarizing plates that can be attached to the outer surface of the liquid crystal cell include a polarizing film called an "H film" made by absorbing iodine while stretching and aligning polyvinyl alcohol, sandwiched between cellulose acetate protective films, and a polarizing plate made of the H film itself.

The liquid crystal display element of the present invention can be effectively applied to various devices, for example, watches, portable games, word processors, notebook computers, car navigation systems, camcorders, PDAs, digital cameras, mobile phones, smartphones, various monitors, liquid crystal televisions, information displays, and other various display devices. In addition, the polymer composition contained in the liquid crystal alignment agent can be used as a liquid crystal alignment film for retardation films, a liquid crystal alignment film for scanning antennas and liquid crystal array antennas, or a liquid crystal alignment film for a transparent scattering type liquid crystal dimming element, or other applications such as a protective film for a color filter, a gate insulating film for a flexible display, and a substrate material.

The present invention will be specifically described below with reference to examples, but the present invention should not be construed as being limited to these examples. The abbreviations of the compounds and the methods for measuring the respective properties are as follows:

(Tetracarboxylic acid dianhydride)
DC-1 to DC-3: Compounds represented by the following formulas (DC-1) to (DC-3)

(Diamine)
DA-1 to DA-11: Compounds represented by the following formulas (DA-1) to (DA-11).

The compound represented by formula (DA-1) was synthesized by the synthesis method described in Non-Patent Document (High Performance Polymers, vol. 31 (9-10), p. 1043-1053 (2019)).
The compound represented by formula (DA-2) was synthesized by the synthesis method described in the non-patent document (Separation and Purification Technology, vol. 235, 116218 (2020)).
The compound represented by formula (DA-3) was synthesized by the synthesis method described in Non-Patent Document (Polymer Science, Series B: Polymer Chemistry, vol. 60(3), 273-282(2018)).

(solvent)
NMP: N-methyl-2-pyrrolidone BCS: Butyl cellosolve (ethylene glycol monobutyl ether)

[viscosity]
The measurements were performed using an E-type viscometer TVE-22H (manufactured by Toki Sangyo Co., Ltd.) with a sample amount of 1.1 mL (milliliters), a cone rotor TE-1 (1°34', R24), and a temperature of 25°C.
[Measurement of molecular weight]
The measurements were carried out using a room temperature gel permeation chromatography (GPC) apparatus (GPC-101, manufactured by Showa Denko K.K.) and columns (GPC KD-803, GPC KD-805, manufactured by Showa Denko K.K.) as follows.
Column temperature: 50°C
Eluent: N,N-dimethylformamide (additives: lithium bromide monohydrate (LiBr.H ₂ O) 30 mmol/L (liter), phosphoric acid anhydrous crystal (o-phosphoric acid) 30 mmol/L, tetrahydrofuran (THF) 10 mL/L)
Flow rate: 1.0 mL/min. Standard samples for preparing a calibration curve: TSK standard polyethylene oxide (molecular weight: about 900,000, 150,000, 100,000, and 30,000) (manufactured by Tosoh Corporation) and polyethylene glycol (molecular weight: about 12,000, 4,000, and 1,000) (manufactured by Polymer Laboratory Co., Ltd.).

[Synthesis of polyamic acid]
<Synthesis Example 1>
In a 100 mL four-necked flask equipped with a stirrer, 2.05 g (6.0 mmol) of DA-1 and 2.80 g (14.0 mmol) of DA-7 were weighed out as diamine components, 19.4 g of NMP was added, and the mixture was stirred and dissolved. While stirring this diamine solution, 4.26 g (19.0 mmol) of DC-1 was added as a tetracarboxylic dianhydride component, and 17.0 g of NMP was further added, and the mixture was stirred at 60° C. for 15 hours to obtain a solution of polyamic acid (A-1, viscosity: 625 mPa·s, number average molecular weight: 7,094).

<Synthesis Examples 2 to 7>
Solutions of polyamic acids (A-2) to (A-7) shown in Table 1 were obtained by carrying out the same procedure as in Synthesis Example 1, except that the diamine component and the tetracarboxylic dianhydride component were changed to those shown in Table 1. The viscosity and molecular weight of the obtained polyamic acids are shown in Table 1.

[Preparation of liquid crystal alignment agent]
Example 1
NMP (6.0 g) and BCS (8.0 g) were added to the solution (6.0 g) of polyamic acid (A-1) obtained above, and the mixture was stirred at room temperature for 10 hours to obtain a liquid crystal alignment agent (PAA-1) having a polyamic acid (A-1) concentration of 6 mass%, a NMP concentration of 54 mass%, and a BCS concentration of 40 mass% in the liquid crystal alignment agent.

<Examples 2 to 3, Comparative Examples 1 to 3, and Preparation Example 1>
The same procedure as in Example 1 was carried out except that the polyamic acid solution was changed to that shown in Table 2 below, to obtain liquid crystal alignment agents (PAA-2) to (PAA-7) shown in Table 2 below.

Example 4
NMP (0.6 g) and BCS (1.4 g) were added to the liquid crystal alignment agent (PAA-1) (4.0 g) obtained above, and the mixture was stirred at room temperature for 10 hours to obtain a liquid crystal alignment agent (PAA-r-1) having a polyamic acid (A-1) concentration of 4 mass%, an NMP concentration of 46 mass%, and a BCS concentration of 50 mass% in the liquid crystal alignment agent.

<Examples 5 to 6 and Comparative Examples 4 to 6>
Except for changing the polyamic acid solution to that shown in Table 3 below, the same procedure as in Example 4 was carried out to obtain liquid crystal alignment agents (PAA-r-2) to (PAA-r-6) shown in Table 3 below.

<Examples 7 to 9 and Comparative Examples 7 to 9>
The liquid crystal alignment agent (PAA-1) obtained in Example 1 and the liquid crystal alignment agent (PAA-7) obtained in Preparation Example 1 were mixed in a mass ratio of 3:7 (PAA-7:PAA-1) and stirred at room temperature for 3 hours to prepare the liquid crystal alignment agent (PAA-b-1) of Example 7.
In addition, the liquid crystal alignment agents (PAA-b-2) to (PAA-b-6) of Examples 8 to 9 and Comparative Examples 7 to 9 shown in Table 4 below were prepared in the same manner as in Example 7, except that the combination of liquid crystal alignment agents used was changed to that shown in Table 4 below.

[Solubility of liquid crystal alignment agent in poor solvent]
The liquid crystal alignment agents prepared in Examples 4 to 6 and Comparative Examples 4 to 6 were left to stand in a freezer at -20°C for 14 hours. After that, they were taken out to room temperature and visually confirmed whether the polymer solid matter had precipitated. The results are shown in Table 5. The case where the polymer had dissolved was marked with "◯", and the case where the polymer had precipitated was marked with "X".

[Measurement of refractive index of liquid crystal alignment film]
The liquid crystal alignment agent prepared in the above Examples 1 to 3 and Comparative Examples 1 to 3 was spin-coated on a silicon wafer, dried on a hot plate at 70°C for 90 seconds, and then baked in a hot air circulation oven at 230°C for 20 minutes to form a liquid crystal alignment film with a thickness of 100 nm. Next, a spectroscopic ellipsometer (M-2000, manufactured by J.A. Woollam Co., Ltd.) was used to measure the refractive index at wavelengths of 250 to 800 nm by fitting using the CAUCHY model. The results are shown in Table 6. Table 6 lists the refractive index at a wavelength of 550 nm. A refractive index of 1.630 or more was rated as "excellent," and a refractive index of less than 1.630 was rated as "unacceptable."

[Preparation of Liquid Crystal Alignment Film and Liquid Crystal Cell]
Using the liquid crystal alignment agents prepared in the above Examples 7 to 9 and Comparative Examples 7 to 9, liquid crystal cells were produced as follows.
Each liquid crystal alignment agent was spin-coated onto the ITO surface of an ITO electrode substrate on which an ITO electrode pattern with a pixel size of 100 μm × 300 μm and a line/space of 5 μm each was formed, and the substrate was dried on a hot plate at 70°C for 90 seconds, and then baked in a hot air circulating oven at 230°C for 30 minutes to form a liquid crystal alignment film with a thickness of 100 nm.
In addition, a liquid crystal alignment agent was spin-coated on the ITO surface on which no electrode pattern was formed, and the resulting film was dried on a hot plate at 70°C for 90 seconds, and then baked in a hot air circulating oven at 230°C for 20 minutes to form a liquid crystal alignment film with a thickness of 100 nm.
For the two substrates described above, 4 μm bead spacers were sprayed on the liquid crystal alignment film of one substrate, and then a sealant (solvent-based thermosetting epoxy resin) was printed on top of the bead spacers. Next, the other substrate was attached to the previous substrate with the side on which the liquid crystal alignment film was formed facing inward, and the sealant was thermally cured to prepare an empty cell. Liquid crystal (MLC-3023, Merck) containing a polymerizable compound was injected into this empty cell by a reduced pressure injection method to prepare a liquid crystal cell.
Thereafter, with a direct current voltage of 15 V applied to the liquid crystal cell, the liquid crystal cell was irradiated from the outside with ultraviolet light having passed through a filter that cuts off wavelengths of 325 nm or less ^at 10 J/cm2. The illuminance of the ultraviolet light was measured using a UV-MO3A manufactured by ORC Corporation. Thereafter, in order to inactivate the unreacted polymerizable compound remaining in the liquid crystal cell, the liquid crystal cell was irradiated with ultraviolet light (UV lamp: FLR40SUV32/A-1) for 30 minutes using a UV-FL irradiation device (manufactured by Toshiba Lighting & Technology Corporation) with no voltage applied.

[Evaluation of vertical alignment]
The evaluation of the vertical alignment of each liquid crystal cell prepared as described above is shown in Table 7. The evaluation method is as follows. Each liquid crystal cell was sandwiched between crossed Nicol polarizers, and with a backlight irradiated from behind, the liquid crystal cell was rotated and visually observed to see whether the liquid crystal was vertically aligned based on the change in light and dark. The evaluation criteria were "good" when the liquid crystal was vertically aligned and "poor" when the liquid crystal was not vertically aligned. The results are shown in Table 7.

Claims (14)

A liquid crystal alignment agent for vertical alignment, comprising a polymer (P) containing at least one selected from the group consisting of polyimide precursors and polyimides obtained using a diamine component containing a diamine (1) represented by the following formula (1):

(Ar represents a phenylene group, Q represents a divalent organic group containing at least one naphthalene ring, Q and each of the two oxygen atoms are bonded on a benzene ring constituting the at least one naphthalene ring, and the benzene ring bonded to one oxygen atom is different from the benzene ring bonded to the other oxygen atom. Any hydrogen atom on the phenylene group may be substituted with at least one selected from the group consisting of an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a fluorine-containing alkyl group having 1 to 3 carbon atoms, a fluorine-containing alkoxy group having 1 to 3 carbon atoms, and a fluorine atom.) 2. The liquid crystal aligning agent for vertical alignment according to claim 1, wherein Q represents a divalent organic group having 10 to 40 carbon atoms and represented by the following formula (f):

( _A1 and _A2 are each independently a naphthalene ring which may have a substituent. _X1 and _X2 are each independently a single bond, an oxygen atom or a sulfur atom. Y is an alkylene group having 1 to 8 carbon atoms, or a divalent organic group containing an oxygen atom or a sulfur atom between the carbon-carbon bonds of an alkylene group having 1 to 8 carbon atoms. m is an integer of 0 to 2, and n is an integer of 0 or 1. * represents a bond.) The liquid crystal aligning agent for vertical alignment according to claim 1 or 2, wherein the diamine (1) is any diamine selected from the group consisting of the following formulas (d-1) to (d-2):

The polymer (P) contains, as a constituent, at least one diamine (s) selected from the group consisting of partial structures represented by the following formulas (S1) to (S3): A liquid crystal alignment agent for vertical alignment according to any one of claims 1 to 3.
( ^X1 and ^X2 each independently represent a single bond, -( _CH2 ) _a- (a is an integer of 1 to 15), -CONH-, -NHCO-, -CON( _CH3 )-, -N( _CH3 )CO-, -NH-, -O-, -COO-, -OCO-, -(( _CH2 ) _a1 - _A1 ) _m1- , or -( _A1- ( _CH2 ) _a1 ) _m1- (a1 is an integer of 1 to 15, _A1 represents an oxygen atom, -COO-, or -OCO-, and m1 is an integer of 1 to 2. When m1 is 2, each of the multiple a1s is independent and each of the multiple _A1s is independent.) ^G1 and G Each of ² independently represents a divalent cyclic group selected from a divalent aromatic group having 6 to 12 carbon atoms and a divalent alicyclic group having 3 to 8 carbon atoms. Any hydrogen atom on the cyclic group may be substituted with at least one selected from the group consisting of an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a fluorine-containing alkyl group having 1 to 3 carbon atoms, a fluorine-containing alkoxy group having 1 to 3 carbon atoms, and a fluorine atom. Each of m and n independently represents an integer of 0 to 3, and the sum of m and n is 1 to 6. ^{R 1} represents 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, and any hydrogen atom forming R ¹ may be substituted with a fluorine atom.
( ^X3 represents a single bond, -CONH-, -NHCO-, -CON( _CH3 )-, -N( _CH3 )CO-, -NH-, -O-, _-CH2O- , -COO- or -OCO-. ^R2 represents an alkyl group having 1 to 20 carbon atoms or an alkoxyalkyl group having 2 to 20 carbon atoms, and any hydrogen atom forming ^R2 may be substituted with a fluorine atom.)
( ^X4 represents -CONH-, -NHCO-, -O-, -COO-, -OCO-, -(( _CH2 ) _a1 - _A1 ) _m1- , or -( _A1- ( _CH2 ) _a1 ) _m1- [a1 is an integer of 1 to 15, _A1 represents an oxygen atom, -COO-, or -OCO-, and m1 is an integer of 1 to 2. When m1 is 2, a1 are each independent and _A1 are each independent.]. ^R3 represents a structure having a steroid skeleton.) The liquid crystal aligning agent for vertical alignment according to claim 4 , wherein the diamine (s) is a diamine represented by the following formula (d1) or formula (d2):

(X is a single bond, -O-, -C(CH ₃ ) ₂ -, -NH-, -CO-, -COO-, -CONH-, -(CH ₂ ) _m -, -SO ₂ -, -O-(CH ₂ ) _m -O-, -O-C(CH ₃ ) ₂ -, -CO-(CH ₂ ) _m -, -CO-(CH ₂ ) _m -CO-, -NH-(CH ₂ ) _m -, -NH-(CH ₂ ) _m -NH-, -SO ₂ -(CH ₂ ) _m -, -SO ₂ -(CH ₂ ) _m -SO ₂ -, -CONH-(CH ₂ ) _m -, -CONH-(CH ₂ ) _m -NHCO-, or -COO-(CH ₂ ) _m represents —OCO—; m is an integer of 1 to 8; and each Y independently represents a partial structure of any one of the formulae (S1) to (S3). The liquid crystal aligning agent for vertical alignment according to claim 5, wherein the diamine represented by the formula (d1) is any diamine selected from the group consisting of the following formulas (d1-1) to (d1-18):

(n is an integer from 1 to 20.)

The liquid crystal aligning agent for vertical alignment according to claim 5, wherein the diamine represented by the formula (d2) is any diamine selected from the group consisting of the following formulas (d2-1) to (d2-6):

(X ^p1 to X ^p8 represent -(CH ₂ ) _a - (a is an integer of 1 to 15), -CONH-, -NHCO-, -CON(CH ₃ )-, -NH-, -O-, -CH ₂ O-, -CH ₂ OCO-, -COO-, or -OCO-. ^{X s1} to X ^s4 each independently represent -O-, -COO-, or -OCO-. _{X a} to X _f each independently represent a single bond, -O-, -NH-, or -O-(CH ₂ ) _m -O- (m is an integer of 1 to 8). R ^1a to R ^1h each independently represent an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, or an alkoxyalkyl group having 2 to 20 carbon atoms.) The polymer (P) contains a tetracarboxylic acid component containing a tetracarboxylic dianhydride represented by the following formula (T) as a constituent component. The liquid crystal alignment agent for vertical alignment according to any one of claims 1 to 7.

(X represents a structure selected from the following (x-1) to (x-13).)

(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. R ⁵ and R ⁶ each independently represent a hydrogen atom or a methyl group. j and k each independently represent an integer of 0 or 1. A ₁ and A ₂ each independently represent a single bond, an ether (-O-), a carbonyl (-CO-), an ester (-COO- or -OCO-), a phenylene group, a sulfonyl group (-SO ₂ -) or an amide group (-CONH- or -NHCO-). *1 represents a bond bonded to one acid anhydride group, and *2 represents a bond bonded to the other acid anhydride group. In the formula (x-13), the two A ₂ may be the same or different from each other.) The liquid crystal aligning agent for vertical alignment according to claim 8, wherein X in the formula (T) is any one of (x-1) to (x-7) and (x-11) to (x-13). The liquid crystal aligning agent for vertical alignment according to any one of claims 1 to 9, wherein the diamine (1) is contained in an amount of 1 to 100 mol % in the total diamine components of the polymer (P). The liquid crystal aligning agent for vertical alignment according to any one of claims 4 to 9, wherein the diamine (s) is contained in an amount of 1 to 99 mol % in the total diamine components of the polymer (P). A liquid crystal alignment film for vertical alignment, formed by using the liquid crystal aligning agent for vertical alignment according to any one of claims 1 to 11. A vertical alignment type liquid crystal display element comprising the liquid crystal alignment film for vertical alignment according to claim 11 . A method for producing a vertical alignment type liquid crystal display element, comprising the following steps (A), (B), and (C):
Step (A): A step of applying the liquid crystal alignment agent for vertical alignment according to any one of claims 1 to 11 onto a pair of substrates having conductive films to form a coating film. Step (B): A step of forming a liquid crystal cell by arranging the coating films so as to face each other via a layer of liquid crystal molecules. Step (C): A step of irradiating the liquid crystal cell with light while applying a voltage between the conductive films of the pair of substrates.