WO2018043325A1 - Liquid crystal alignment agent, liquid crystal alignment film, and liquid crystal display element using same - Google Patents

Abstract

Provided is a liquid crystal alignment agent with which it is possible to form a liquid crystal film that has excellent electric properties, such as release of stored charge, and transparency without undergoing coloring. This liquid crystal alignment agent is characterized by containing at least one polymer selected from the group consisting of: polyamic acids obtained through reaction between a tetracarboxylic acid dianhydride component and a diamine component containing a diamine having the structure represented by formula [1]; and polyimides obtained by imidizing said polyamic acids. (A represents a thermally cleavable group that is substituted with a hydrogen atom when heated to 150-300°C. The hydrogen atoms in the benzene ring may be substituted with a halogen group, or an alkoxy group or an alkyl group having 1-5 carbon atoms. "*" represents a bond.)

Description

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

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

The liquid crystal alignment film is a constituent member of a liquid crystal display element widely used as a display device, and plays a role of aligning liquid crystals in a certain direction. Currently, the main liquid crystal alignment film used industrially is formed from a liquid crystal aligning agent made of a polyimide precursor polyamic acid (also referred to as polyamic acid) or a polyimide solution. Specifically, it is obtained by applying a liquid crystal alignment agent to a substrate, heating and baking, and then performing a liquid crystal alignment treatment.

Conventionally, surface treatment by rubbing is mainly performed as the liquid crystal alignment treatment. However, in the rubbing treatment, it is usually difficult to perform highly uniform alignment treatment, and liquid crystal alignment defects and defects in the liquid crystal alignment film are caused. Occasionally, display defects may occur, and there may be problems such as dust generation. In recent years, there has been a tendency to increase the area of the substrate and increase the unevenness due to the increase in size, definition, and cost of the substrate used for the panel. When forming an alignment film on such a substrate, rubbing is performed. Processing still leaves room for improvement.

On the other hand, an alignment process using a photoreaction has been proposed as an alignment process method instead of the rubbing method. Specifically, a method of imparting liquid crystal alignment ability by forming a polymer film having a specific site causing a photoreaction such as polyvinyl cinnamate on the substrate surface and irradiating with polarized or non-polarized radiation ( The photo-alignment method) is known. According to this method, uniform liquid crystal alignment can be realized without generating static electricity or dust, and viewing angle can be improved by alignment division (see Patent Documents 1 and 2).

Further, in liquid crystal cells such as TN (Twisted Nematic) and STN (Super Twisted Nematic), the liquid crystal alignment film needs to have a function of tilting and aligning liquid crystal molecules at a predetermined angle (pretilt angle) with respect to the substrate surface. . In order to develop a pretilt angle, a liquid crystal alignment film using a polyamic acid or polyimide having an alkyl side chain, a side chain of a steroid skeleton, a side chain having a ring structure, or the like is known (Patent Documents 3 and 4). 5). In the alignment treatment using light, the pretilt angle is usually given by irradiation with radiation whose incident direction to the substrate surface is inclined with respect to the normal direction of the substrate (see Patent Document 1).

Japanese Unexamined Patent Publication No. 6-287453 Japanese Unexamined Patent Publication No. 9-297313 Japanese Unexamined Patent Publication No. 05-043687 Japanese Unexamined Patent Publication No. 04-281427 Japan Kaihei 02-223916

As described above, conventionally, the main liquid crystal alignment film is formed of a liquid crystal alignment agent composed of a polyamic acid or polyimide solution which is a polyimide precursor. There are various problems due to enlargement, high definition, low cost, etc., and there is room for improvement. In order to solve one of such problems, a polyamic acid obtained by reacting a diamine represented by the following formula (DA-3) with a tetracarboxylic dianhydride component, and / or Or the liquid crystal aligning agent containing the polyimide obtained by imidating this polyamic acid is proposed.

　かかる液晶配向剤から得られる液晶配向膜を具備した液晶表示素子は、電気特性（蓄積電荷の抜けなど）の点で優れた特性を有する。一方、かかる液晶配向剤を使用した場合、得られる液晶配向膜が、黒褐色に着色しかつ透明性が失われ、結果として、液晶配向膜を有する液晶配向素子に悪影響を与える場合があることが判明した。

A liquid crystal display device provided with a liquid crystal alignment film obtained from such a liquid crystal aligning agent has excellent characteristics in terms of electrical characteristics (such as loss of accumulated charge). On the other hand, when such a liquid crystal aligning agent is used, it turns out that the obtained liquid crystal aligning film is colored black brown and loses transparency, and as a result, the liquid crystal aligning element having the liquid crystal aligning film may be adversely affected. did.

The present invention, while maintaining the excellent characteristics due to the use of the diamine compound as a raw material of the polyamic acid that is a polymer contained in the liquid crystal alignment agent, while the obtained liquid crystal alignment film is colored black brown and It aims at providing the liquid crystal aligning agent which does not have a bad influence on liquid crystal aligning elements, such as loss of transparency.

（式中、Ａは、温度１５０～３００℃の加熱により水素原子に置き換わる熱脱離性基を表す。ベンゼン環の有する水素原子は、炭素数１～５のアルキル基、炭素数１～５のアルコキシ基、又はハロゲン基により、置換されていてもよい。＊は結合手を表す。） As a result of intensive studies to achieve the above object, the present inventors have completed the present invention.
The present invention includes a polyamic acid obtained by a reaction of a diamine component containing a diamine having a structure represented by the following formula [1] and a tetracarboxylic dianhydride component, and a polyimide obtained by imidizing the polyamic acid. The gist of the present invention is a liquid crystal aligning agent containing at least one polymer selected from the group consisting of:

(In the formula, A represents a heat-eliminable group that is replaced with a hydrogen atom by heating at a temperature of 150 to 300 ° C. The hydrogen atom of the benzene ring is an alkyl group having 1 to 5 carbon atoms, or a carbon atom having 1 to 5 carbon atoms. (It may be substituted with an alkoxy group or a halogen group. * Represents a bond.)

The liquid crystal aligning agent of this invention contains the polyamic acid which uses the diamine represented by Formula [1] (henceforth a specific diamine) as a raw material, and / or the polyimide obtained by imidating this polyamic acid. However, such a polymer has a very high solubility in a polar solvent such as N-methylpyrrolidone (NMP) and has good handling during polymerization, and a liquid crystal aligning agent containing such a polymer is coated. -A liquid crystal alignment film excellent in film formability and further suppressed in voltage drop even when exposed to light can be obtained.
In addition, the liquid crystal aligning agent of the present invention is a liquid crystal aligning film obtained as compared with a liquid crystal aligning agent containing a polyamic acid or a polyimide thereof using a diamine compound (DA-3) described later having a structure similar to a specific amine as a raw material. However, since it is not colored black-brown and has transparency, a liquid crystal alignment film that does not adversely affect the liquid crystal display element can be formed.

The reason why the liquid crystal aligning agent of the present invention can provide the excellent effects as described above is estimated as follows. That is, the diamine of the above formula (DA-3) having the same structure of the same diphenylamine skeleton as the specific diamine has a secondary amino group that is more reactive than the primary amino group in the structure. The secondary amino group reacts in a reaction process with a tetracarboxylic dianhydride component for obtaining a polyamic acid, and an undesirable three-dimensional reaction occurs. As a result, it is considered that the obtained reaction product causes a coloring phenomenon and the characteristics as a liquid crystal aligning agent are deteriorated.

On the other hand, the specific diamine of the present invention has, in its structure, a secondary amino group that is highly reactive as in the above formula (DA-3), but the secondary amino group is protected with a thermally desorbable group. Therefore, in the reaction process with the tetracarboxylic dianhydride component to obtain a polyamic acid, an undesirable three-dimensional reaction does not occur, resulting in no coloring phenomenon and characteristics as a liquid crystal aligning agent. Seems not to decline.
Further, in the liquid crystal aligning agent of the present invention, the polyamic acid or polyimide which is a polymer to be contained has an amino group protected with a thermally detachable group, but is protected with this thermally detachable group. As described later, in the process of forming a liquid crystal alignment film by applying a liquid crystal aligning agent to a substrate and baking it, the heat-releasable group is deprotected and converted into an amino group by heating in the baking process. Can be made.

The deprotected amino group regains the reactivity again, and the amino group generated by the elimination reacts in the molecule to form a heterocyclic ring and the like, thereby generating a rigid side chain. It will function as a good induction site for the pretilt angle. In addition, not all of the amino groups from which the heat-eliminable group is removed are used for the cyclization reaction, and some of them are also used for intermolecular reactions. Crosslinking with molecular components contributes to improved reliability.
Thus, the polyamic acid or polyimide using the specific diamine of the present invention is less prone to scraping during rubbing treatment, and even when exposed to high temperature, backlight irradiation, etc. for a long period of time, the voltage holding ratio decreases and the ion density The increase of is difficult to occur.

　上記式［１］中、Ａは、本発明の液晶配向剤の焼成温度である、１５０～３００℃の加熱により水素に置き換わる熱脱離性基である。この熱脱離性基は、好ましくは１７０～３００℃、特に好ましくは１８０～２５０℃で脱離が可能であれば好適である。＊は結合手を表す。 <Specific diamine of the present invention>
The diamine used as a raw material for the liquid crystal aligning agent of the present invention is a diamine having a structure represented by the following formula [1].

In the above formula [1], A is a thermally desorbable group that is replaced with hydrogen by heating at 150 to 300 ° C., which is the firing temperature of the liquid crystal aligning agent of the present invention. This thermally leaving group is preferably 170 to 300 ° C., particularly preferably 180 to 250 ° C. if it can be removed. * Represents a bond.

Examples of the thermal leaving group include carbamate organic compounds represented by benzyloxycarbonyl group, 9-fluorenylmethyloxycarbonyl group, allyloxycarbonyl group, tertiary butoxycarbonyl group (also referred to as Boc group), and the like. Groups. A Boc group or a 9-fluorenylmethoxycarbonyl group is particularly preferred from the viewpoint that the elimination efficiency is high and the gas is harmless at the time of elimination at a relatively low temperature.

The hydrogen atom of the benzene ring in the formula [1] is optionally substituted with an alkyl group or alkoxy group having 1 to 5, preferably 1 to 3 carbon atoms, or a halogen group such as chlorine, bromine or fluorine. May be.
The amino group possessed by the specific diamine is preferably a primary amino group. Further, for example, it may be a secondary amino group substituted with an alkyl group having a relatively small molecular weight such as a methyl group, an ethyl group, a propyl group, or a butyl group.
Specific examples of the specific diamine include, but are not limited to, the following. In the formula, Boc represents a tert-butoxycarbonyl group.

<Tetracarboxylic dianhydride component>
In order to obtain the polyimide precursor of the present invention, a tetracarboxylic dianhydride (also referred to as a specific tetracarboxylic dianhydride) represented by the following formula [7] is used as a part of the tetracarboxylic dianhydride component. It is preferable to use it.

　式［７］中、Ｚ_１は、炭素数４～１３の４価の有機基であり、かつ、芳香族環状炭化水素基を有する。具体的には、下記式［７ａ］～［７k］のいずれかで表される基が好ましい。

In the formula [7], Z ₁ is a tetravalent organic group having 4 to 13 carbon atoms and has an aromatic cyclic hydrocarbon group. Specifically, a group represented by any of the following formulas [7a] to [7k] is preferable.

In the formula [7], a preferred group represented by Z _{1 is} a group represented by the formula [7a] or the formula [7g] in view of polymerization reactivity and ease of synthesis. Of these, the formula [7a] is most preferable.
When the tetracarboxylic dianhydride having the structure of the formula [7a] is used, it is preferably 20% by mass or more of the total tetracarboxylic dianhydride component, more preferably 30% by mass or more. is there. All of the tetracarboxylic acid components used for the production of the polyimide precursor may be tetracarboxylic dianhydrides having the structure of the formula [7a].

In the present invention, an aliphatic tetracarboxylic dianhydride other than the specific tetracarboxylic dianhydride and other tetracarboxylic acid components can be used.
Examples of the aliphatic tetracarboxylic dianhydride include 1,2,3,4-butanetetracarboxylic dianhydride. Examples of the alicyclic tetracarboxylic dianhydride include 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-tetramethyl-1,2,3,4- Cyclobutanetetracarboxylic dianhydride, 1,2-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride 1,3-diphenyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 1,2,4,5-cyclohexane Tetracarboxylic dianhydride, 1,2,3,4-cycloheptanetetracarboxylic dianhydride, 2,3,4,5-tetrahydrofurantetracarboxylic dianhydride, 3,4-dicarboxy-1-cycl Hexylsuccinic dianhydride, 2,3,5-tricarboxycyclopentylacetic acid dianhydride, 3,4-dicarboxy-1,2,3,4-tetrahydro-1-naphthalene succinic dianhydride, bicyclo [3 , 3,0] octane-2,4,6,8-tetracarboxylic dianhydride, bicyclo [4,3,0] nonane-2,4,7,9-tetracarboxylic dianhydride, bicyclo [4 , 4,0] decane-2,4,7,9-tetracarboxylic dianhydride, bicyclo [4,4,0] decane-2,4,8,10-tetracarboxylic dianhydride, tricyclo [6 .3.0.0 <2,6>] undecane-3,5,9,11-tetracarboxylic dianhydride, 4- (2,5-dioxotetrahydrofuran-3-yl) -1,2,3 , 4-Tetrahydraphthalene-1,2-dicarboxylic acid Anhydride, bicyclo [2,2,2] oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, 5- (2,5-dioxotetrahydrofuryl) -3-methyl-3 -Cyclohexane-1,2-dicarboxylic dianhydride, tetracyclo [6,2,1,1,0,2,7] dodeca-4,5,9,10-tetracarboxylic dianhydride, 3, And 5,6-tricarboxynorbornane-2: 3,5: 6 dicarboxylic dianhydride.
Other tetracarboxylic acid components include tetracarboxylic acid, tetracarboxylic acid dihalide, tetracarboxylic dianhydride, esterified product obtained by dialkyl esterifying the carboxylic acid group of tetracarboxylic acid, and dialkyl carboxylic acid group of tetracarboxylic acid dihalide. Examples include esterified esterified products.

The above-mentioned other tetracarboxylic acid components can be used alone or in combination of two or more kinds in consideration of characteristics such as liquid crystal alignment properties, voltage holding characteristics and accumulated charges of the liquid crystal alignment film to be formed.

<Polymer of the present invention>
The polymer in the present invention means a polyamic acid and / or a polyimide obtained by imidizing the polyamic acid.

<Polyamic acid>
The polyamic acid of the present invention is obtained by a reaction between a diamine component containing a specific diamine and a tetracarboxylic dianhydride component.
In the diamine component for obtaining a polyamic acid by reaction with the tetracarboxylic dianhydride component, the content ratio of the specific diamine is not limited. The content of the specific diamine in the diamine component may be 100%. However, various diamines can be used in combination because they satisfy various characteristics required for the liquid crystal alignment film, such as characteristics that increase the pretilt angle of the liquid crystal and vertical alignment characteristics of the liquid crystal. it can. Accordingly, the content ratio of the specific diamine in the diamine component used for the polymerization is preferably 1 to 50 mol%, particularly preferably 5 to 30 mol%.

In the above diamine component, the diamine other than the specific diamine (hereinafter also referred to as other diamine) used in combination when the specific diamine is less than 100 mol% includes an alicyclic diamine, an aromatic-aliphatic diamine, a heterocyclic ring. Formula diamine, aliphatic diamine, etc. are mentioned.

Examples of alicyclic diamines include 1,4-diaminocyclohexane, 1,3-diaminocyclohexane, 4,4′-diaminodicyclohexylmethane, 4,4′-diamino-3,3′-dimethyldicyclohexylamine, isophorone diamine Etc.
Examples of aromatic diamines include o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, 2,4-diaminotoluene, 2,5-diaminotoluene, 3,5-diaminotoluene, 1,4-diamino -2-methoxybenzene, 2,5-diamino-p-xylene, 1,3-diamino-4-chlorobenzene, 3,5-diaminobenzoic acid, 1,4-diamino-2,5-dichlorobenzene, 4,4 '-Diamino-1,2-diphenylethane, 4,4'-diamino-2,2'-dimethylbibenzyl, 4,4'-diaminodiphenylmethane, 3,3'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane 4,4′-diamino-3,3′-dimethyldiphenylmethane, 2,2′-diaminostilbene, 4,4′-diaminostilbene, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, 4,4'-diaminobenzophenone 1,3-bis (3-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) benzene, 3,5-bis (4-aminophenoxy) ) Benzoic acid, 4,4′-bis (4-aminophenoxy) bibenzyl, 2,2-bis [(4-aminophenoxy) methyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] Hexafluoropropane, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, bis [4- (3-aminophenyl) Enoxy) phenyl] sulfone, bis [4- (4-aminophenoxy) phenyl] sulfone, 1,1-bis (4-aminophenyl) cyclohexane, α, α′-bis (4-aminophenyl) -1,4- Diisopropylbenzene, 9,9-bis (4-aminophenyl) fluorene, 2,2-bis (3-aminophenyl) hexafluoropropane, 2,2-bis (4-aminophenyl) hexafluoropropane, 4,4 ′ -Diaminodiphenylamine, 2,4-diaminodiphenylamine, 1,8-diaminonaphthalene, 1,5-diaminonaphthalene, 1,5-diaminoanthraquinone, 1,3-diaminopyrene, 1,6-diaminopyrene, 1,8- Diaminopyrene, 2,7-diaminofluorene, 1,3-bis (4-aminophenyl) tetramethyldisi Xanthone, benzidine, 2,2'-dimethylbenzidine, 1,2-bis (4-aminophenyl) ethane, 1,3-bis (4-aminophenyl) propane, 1,4-bis (4-aminophenyl) butane 1,5-bis (4-aminophenyl) pentane, 1,6-bis (4-aminophenyl) hexane, 1,7-bis (4-aminophenyl) heptane, 1,8-bis (4-aminophenyl) ) Octane, 1,9-bis (4-aminophenyl) nonane, 1,10-bis (4-aminophenyl) decane, 1,3-bis (4-aminophenoxy) propane, 1,4-bis (4- Aminophenoxy) butane, 1,5-bis (4-aminophenoxy) pentane, 1,6-bis (4-aminophenoxy) hexane, 1,7-bis (4-aminophenoxy) heptane 1,8-bis (4-aminophenoxy) octane, 1,9-bis (4-aminophenoxy) nonane, 1,10-bis (4-aminophenoxy) decane, di (4-aminophenyl) propane-1, 3-dioate, di (4-aminophenyl) butane-1,4-dioate, di (4-aminophenyl) pentane-1,5-dioate, di (4-aminophenyl) hexane-1,6-dioate, di (4-aminophenyl) heptane-1,7-dioate, di (4-aminophenyl) octane-1,8-dioate, di (4-aminophenyl) nonane-1,9-dioate, di (4-aminophenyl) ) Decane-1,10-dioate, 1,3-bis [4- (4-aminophenoxy) phenoxy] propane, 1,4-bis [4- (4-aminopheno) Phenoxy] butane, 1,5-bis [4- (4-aminophenoxy) phenoxy] pentane, 1,6-bis [4- (4-aminophenoxy) phenoxy] hexane, 1,7-bis [4- (4-aminophenoxy) phenoxy] heptane, 1,8-bis [4- (4-aminophenoxy) phenoxy] octane, 1,9-bis [4- (4-aminophenoxy) phenoxy] nonane, 1,10- And bis [4- (4-aminophenoxy) phenoxy] decane.

Examples of aromatic-aliphatic diamines include 3-aminobenzylamine, 4-aminobenzylamine, 3-amino-N-methylbenzylamine, 4-amino-N-methylbenzylamine, 3-aminophenethylamine, 4-aminobenzylamine, Aminophenethylamine, 3-amino-N-methylphenethylamine, 4-amino-N-methylphenethylamine, 3- (3-aminopropyl) aniline, 4- (3-aminopropyl) aniline, 3- (3-methylaminopropyl) Aniline, 4- (3-methylaminopropyl) aniline, 3- (4-aminobutyl) aniline, 4- (4-aminobutyl) aniline, 3- (4-methylaminobutyl) aniline, 4- (4-methyl Aminobutyl) aniline, 3- (5-aminopentyl) aniline, 4- (5-aminopentyl) Aniline, 3- (5-methylaminopentyl) aniline, 4- (5-methylaminopentyl) aniline, 2- (6-aminonaphthyl) methylamine, 3- (6-aminonaphthyl) methylamine, 2- (6 -Aminonaphthyl) ethylamine, 3- (6-aminonaphthyl) ethylamine and the like.

Examples of heterocyclic diamines include 2,6-diaminopyridine, 2,4-diaminopyridine, 2,4-diamino-1,3,5-triazine, 2,7-diaminodibenzofuran, 3,6-diaminocarbazole 2,4-diamino-6-isopropyl-1,3,5-triazine, 2,5-bis (4-aminophenyl) -1,3,4-oxadiazole and the like.
Examples of aliphatic diamines include 1,2-diaminoethane, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, 1,10-diaminodecane, 1,3-diamino-2,2-dimethylpropane, 1,6-diamino-2,5-dimethylhexane, 1,7- Diamino-2,5-dimethylheptane, 1,7-diamino-4,4-dimethylheptane, 1,7-diamino-3-methylheptane, 1,9-diamino-5-methylheptane, 1,12-diaminododecane 1,18-diaminooctadecane, 1,2-bis (3-aminopropoxy) ethane and the like.

（Ｒ_６は、炭素数１～２２を有する、アルキル基又はフッ素含有アルキル基である。） You may use together the diamine compound which has an alkyl group, a fluorine-containing alkyl group, an aromatic ring, an aliphatic ring, a heterocyclic ring, or the macrocyclic substituent which consists of them in a side chain. Specifically, diamines represented by the following formulas [DA1] to [DA26] are exemplified.

(R ₆ is an alkyl group or a fluorine-containing alkyl group having 1 to 22 carbon atoms.)

（Ｓ_５は、－ＣＯＯ－、－ＯＣＯ－、－ＣＯＮＨ－、－ＮＨＣＯ－、－ＣＨ_２－、－Ｏ－、－ＣＯ－、又は－ＮＨ－を示し、Ｒ_６は炭素数１～２２を有する、アルキル基若しくはフッ素含有アルキル基を示す。）

(S ₅ represents —COO—, —OCO—, —CONH—, —NHCO—, —CH ₂ —, —O—, —CO—, or —NH—, and R ₆ represents 1 to 22 carbon atoms. It has an alkyl group or a fluorine-containing alkyl group.)

（Ｓ_６は、－Ｏ－、－ＯＣＨ_２－、－ＣＨ_２Ｏ－、－ＣＯＯＣＨ_２－、又は－ＣＨ_２ＯＣＯ－を示し、Ｒ_７は炭素数１～２２を有する、アルキル基、アルコキシ基、フッ素含有アルキル基若しくはフッ素含有アルコキシ基である。）

(S ₆ represents —O—, —OCH ₂ —, —CH ₂ O—, —COOCH ₂ —, or —CH ₂ OCO—, and R ₇ represents an alkyl group or alkoxy group having 1 to 22 carbon atoms. , A fluorine-containing alkyl group or a fluorine-containing alkoxy group.)

（Ｓ_７は、－ＣＯＯ－、－ＯＣＯ－、－ＣＯＮＨ－、－ＮＨＣＯ－、－ＣＯＯＣＨ_２－、－ＣＨ_２ＯＣＯ－、－ＣＨ_２Ｏ－、－ＯＣＨ_２－、又は－ＣＨ_２－を示し、Ｒ_８は炭素数１～２２を有する、アルキル基、アルコキシ基、フッ素含有アルキル基若しくはフッ素含有アルコキシ基である。）

(S ₇ represents —COO—, —OCO—, —CONH—, —NHCO—, —COOCH ₂ —, —CH ₂ OCO—, —CH ₂ O—, —OCH ₂ —, or —CH ₂ —. R ₈ represents an alkyl group, an alkoxy group, a fluorine-containing alkyl group or a fluorine-containing alkoxy group having 1 to 22 carbon atoms.)

（Ｓ_８は、－ＣＯＯ－、－ＯＣＯ－、－ＣＯＮＨ－、－ＮＨＣＯ－、－ＣＯＯＣＨ_２－、－ＣＨ_２ＯＣＯ－、－ＣＨ_２Ｏ－、－ＯＣＨ_２－、－ＣＨ_２－、－Ｏ－、又は－ＮＨ－を示し、Ｒ_９はフッ素基、シアノ基、トリフルオロメタン基、ニトロ基、アゾ基、ホルミル基、アセチル基、アセトキシ基、又は水酸基である。）

(S ₈ is —COO—, —OCO—, —CONH—, —NHCO—, —COOCH ₂ —, —CH ₂ OCO—, —CH ₂ O—, —OCH ₂ —, —CH ₂ —, —O — Represents — or —NH—, and R ₉ represents a fluorine group, a cyano group, a trifluoromethane group, a nitro group, an azo group, a formyl group, an acetyl group, an acetoxy group, or a hydroxyl group.

（Ｒ₁₀は炭素数３～１２のアルキル基であり、１，４－シクロへキシレンのシス－トランス異性は、それぞれトランス体である。）

(R ₁₀ is an alkyl group having 3 to 12 carbon atoms, and the cis-trans isomerism of 1,4-cyclohexylene is a trans isomer.)

In the case of aligning with light, it is preferable to use a specific diamine in combination with the diamines [DA-1] to [DA-26] because a more stable pretilt angle can be obtained. More preferred diamines that can be used in combination are those represented by the formulas [DA-10] to [DA-26], more preferably diamines of [DA-10] to [DA-16]. The preferred content of these diamines is not particularly limited, but is preferably 5 to 50 mol% in the diamine component, and is preferably 5 to 30 mol% in terms of printability.
Moreover, you may use the following diamine together.

（ｍは０～３の整数であり、式［ＤＡ－３４］中、ｎは１～５の整数である）。
　式[ＤＡ－２７]、式[ＤＡ－２８]等のジアミンを含有させることにより、液晶配向膜とした際の電圧保持特性を向上させることができ、式[ＤＡ－２９]～［ＤＡ－３４］のジアミンは蓄積電化の低減に効果がある。

(M is an integer of 0 to 3, and n is an integer of 1 to 5 in the formula [DA-34]).
By containing a diamine of formula [DA-27], formula [DA-28] or the like, the voltage holding characteristics when a liquid crystal alignment film is formed can be improved. Formulas [DA-29] to [DA-34 ] Is effective in reducing the accumulation of electricity.

（ｍは、１～１０の整数である。）
　その他のジアミンは、液晶配向膜とした際の液晶配向性、電圧保持特性、蓄積電荷などの特性に応じて、１種、又は２種以上を混合して使用することもできる。 Furthermore, diaminosiloxanes represented by the following formula [DA-35] can also be mentioned as other diamines.

(M is an integer from 1 to 10.)
Other diamines can be used singly or in combination of two or more depending on properties such as liquid crystal alignment properties, voltage holding properties, and accumulated charges when the liquid crystal alignment film is formed.

<Production of polyamic acid>
As a method for obtaining the polyamic acid of the present invention by the reaction of the tetracarboxylic dianhydride component and the diamine component, a known method can be used. In general, the tetracarboxylic dianhydride component and the diamine component are reacted in an organic solvent. The reaction between the tetracarboxylic dianhydride component and the diamine is advantageous in that it proceeds relatively easily in an organic solvent and no by-products are generated.

The organic solvent used for the reaction between the tetracarboxylic dianhydride component and the diamine is not limited as long as the produced polyamic acid dissolves. Specific examples are given below.
N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-methylcaprolactam, dimethyl sulfoxide, tetramethyl urea, pyridine, dimethyl sulfone, hexamethyl sulfoxide , Γ-butyrolactone, isopropyl alcohol, methoxymethylpentanol, dipentene, ethyl amyl ketone, methyl nonyl ketone, methyl ethyl ketone, methyl isoamyl ketone, methyl isopropyl ketone, methyl cellosolve, ethyl cellosolve, methyl cellosolve acetate, ethyl cellosolve acetate, butyl Carbitol, ethyl carbitol, ethylene glycol, ethylene glycol monoacetate, ethylene glycol monoisopropyl ether, ethyl Glycol monobutyl ether, propylene glycol, propylene glycol monoacetate, propylene glycol monomethyl ether, propylene glycol-tert-butyl ether, dipropylene glycol monomethyl ether, diethylene glycol, diethylene glycol monoacetate, diethylene glycol dimethyl ether, dipropylene glycol monoacetate monomethyl ether, dipropylene glycol Monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monoacetate monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monoacetate monopropyl ether, 3-methyl-3-methoxybutyl acetate, tripropylene Glycol methyl ether, 3-methyl-3-methoxybutanol, diisopropyl ether, ethyl isobutyl ether, diisobutylene, amyl acetate, butyl butyrate, butyl ether, diisobutyl ketone, methylcyclohexene, propyl ether, dihexyl ether, dioxane, n- Hexane, n-pentane, n-octane, diethyl ether, cyclohexanone, ethylene carbonate, propylene carbonate, methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, n-butyl acetate, propylene glycol monoethyl ether, methyl pyruvate, Ethyl pyruvate, methyl 3-methoxypropionate, methyl ethyl 3-ethoxypropionate, ethyl 3-methoxypropionate, 3-ethoxypropion , 3-methoxypropionic acid, propyl 3-methoxypropionate, butyl 3-methoxypropionate, diglyme, 4-hydroxy-4-methyl-2-pentanone, 3-methoxy-N, N-dimethylpropanamide, 3-ethoxy -N, N-dimethylpropanamide, 3-butoxy-N, N-dimethylpropanamide and the like. These may be used alone or in combination. Furthermore, even if it is a solvent which does not dissolve a polyamic acid, you may mix and use it for the said solvent in the range which the produced | generated polyamic acid does not precipitate.

Moreover, since water in the organic solvent inhibits the polymerization reaction and further causes hydrolysis of the produced polyamic acid, the organic solvent is preferably dehydrated and dried as much as possible.
When the tetracarboxylic dianhydride component and the diamine component are reacted in an organic solvent, the solution in which the diamine component is dispersed or dissolved in the organic solvent is stirred, and the tetracarboxylic dianhydride component is used as it is or in an organic solvent. A method of adding by dispersing or dissolving in a solvent, a method of adding a diamine component to a solution in which a tetracarboxylic dianhydride component is dispersed or dissolved in an organic solvent, and a tetracarboxylic dianhydride component and a diamine component. The method of adding alternately etc. is mentioned, You may use any of these methods. In addition, when the tetracarboxylic dianhydride component or the diamine component is composed of a plurality of types of compounds, they may be reacted in a premixed state, may be individually reacted sequentially, or may be further reacted individually. The body may be mixed and reacted to form a high molecular weight body.

The temperature at which the tetracarboxylic dianhydride component reacts with the diamine component can be selected from -20 to 150 ° C, but is preferably in the range of -5 to 100 ° C. The reaction can be carried out at any concentration, but if the concentration is too low, it is difficult to obtain a high molecular weight polymer, and if the concentration is too high, the viscosity of the reaction solution becomes too high and uniform stirring is difficult. Therefore, the total concentration of the tetracarboxylic dianhydride component and the diamine component in the reaction solution is preferably 1 to 50% by mass, more preferably 5 to 30% by mass. The initial stage of the reaction is carried out at a high concentration, and then an organic solvent can be added.
In the polymerization reaction of polyamic acid, the ratio of the total number of moles of the tetracarboxylic dianhydride component to the total number of moles of the diamine component is preferably 0.8 to 1.2, preferably 0.9 to 1. 1 is more preferable. Similar to the normal polycondensation reaction, the molecular weight of the polyamic acid produced increases as the molar ratio approaches 1.0.

<Manufacture of polyimide>
The polyimide of the present invention is a polyimide obtained by dehydrating and ring-closing the polyamic acid, and is useful as a polymer for obtaining a liquid crystal alignment film.
In the polyimide of the present invention, the dehydration cyclization rate (imidation rate) of the amic acid group is not necessarily 100%, and can be arbitrarily adjusted according to the application and purpose.
Examples of the method for imidizing a polyamic acid include a thermal imidization method in which a polyamic acid solution is heated as it is, and a catalyst imidation method in which a catalyst is added to the polyamic acid solution.
The temperature at which the polyamic acid is thermally imidized in the solution is 100 to 400 ° C., preferably 120 to 250 ° C., and is preferably carried out while removing water generated by the imidization reaction from the system.

The catalytic imidation of polyamic acid can be carried out by adding a basic catalyst and an acid anhydride to a polyamic acid solution and stirring at -20 to 250 ° C., preferably 0 to 180 ° C. The amount of the basic catalyst is 0.5 to 30 mol times, preferably 2 to 20 mol times the amidic acid group, and the amount of the acid anhydride is 1 to 50 mol times, preferably 3 to 3 times the amido group. 30 mole times. Examples of the basic catalyst include pyridine, triethylamine, trimethylamine, tributylamine, trioctylamine and the like. Among them, pyridine is preferable because it has basicity suitable for proceeding with the reaction. Examples of the acid anhydride include acetic anhydride, trimellitic anhydride, pyromellitic anhydride, and the like. Among them, use of acetic anhydride is preferable because purification after completion of the reaction is facilitated. The imidization rate by catalytic imidation can be controlled by adjusting the amount of catalyst, reaction temperature, reaction time, and the like.

The molecular weight of the polymer contained in the liquid crystal aligning agent of the present invention is determined by GPC (Gel Permeation Chromatography) method in consideration of the strength of the obtained coating film, workability at the time of coating film formation, and uniformity of the coating film. The measured weight average molecular weight is preferably 5,000 to 1,000,000, and more preferably 10,000 to 150,000.

<Liquid crystal aligning agent>
The liquid crystal aligning agent of this invention is a coating liquid for forming a liquid crystal aligning film, and is a solution which the resin component for forming a resin film melt | dissolved in the organic solvent. Here, the said resin component contains at least 1 type of polymer chosen from the polymer of above-described this invention. The content of the resin component in the liquid crystal aligning agent is preferably 1 to 20% by mass, more preferably 3 to 15% by mass, and particularly preferably 3 to 10% by mass.
All of the resin components may be the polymer of the present invention, or other polymers may be mixed. In that case, the content of the other polymer in the resin component is 0.5 to 15% by mass, preferably 1 to 10% by mass.
Examples of such other polymer include polyamic acid or polyimide obtained by using a diamine compound other than the specific diamine compound as a diamine component to be reacted with the tetracarboxylic dianhydride component.

The organic solvent used for the liquid crystal aligning agent of this invention will not be specifically limited if it is an organic solvent in which a resin component is dissolved. Specific examples are given below.
N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methylcaprolactam, 2-pyrrolidone, N-ethylpyrrolidone, N-vinylpyrrolidone, dimethylsulfoxide, tetramethylurea, pyridine, Dimethylsulfone, hexamethylsulfoxide, γ-butyrolactone, 3-methoxy-N, N-dimethylpropanamide, 3-ethoxy-N, N-dimethylpropanamide, 3-butoxy-N, N-dimethylpropanamide, 1,3 -Dimethyl-imidazolidinone, ethyl amyl ketone, methyl nonyl ketone, methyl ethyl ketone, methyl isoamyl ketone, methyl isopropyl ketone, cyclohexanone, ethylene carbonate, propylene carbonate, diglyme, 4-hydroxy-4 Such as methyl-2-pentanone and the like. These may be used alone or in combination.

The liquid crystal aligning agent of this invention may contain components other than the above. Examples thereof include compounds that improve the adhesion between the liquid crystal alignment film and the substrate, such as a solvent-rich substance that improves film thickness uniformity and surface smoothness when a liquid crystal aligning agent is applied.
The following are mentioned as a specific example of the solvent (poor solvent) which improves the uniformity of film thickness and surface smoothness.

For example, isopropyl alcohol, methoxymethylpentanol, methyl cellosolve, ethyl cellosolve, butyl cellosolve, methyl cellosolve acetate, ethyl cellosolve acetate, butyl carbitol, ethyl carbitol, ethyl carbitol acetate, ethylene glycol, ethylene glycol monoacetate, ethylene glycol monoacetate Isopropyl ether, ethylene glycol monobutyl ether, propylene glycol, propylene glycol monoacetate, propylene glycol monomethyl ether, propylene glycol-tert-butyl ether, dipropylene glycol monomethyl ether, diethylene glycol, diethylene glycol monoacetate, diethylene glycol dimethyl ether, dipro Lenglycol monoacetate monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monoacetate monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monoacetate monopropyl ether, dipropylene glycol dimethyl ether, 3-methyl-3-methoxybutyl acetate, tripropylene glycol methyl ether, 3-methyl-3-methoxybutanol, diisopropyl ether, ethyl isobutyl ether, diisobutylene, amyl acetate, butyl butyrate, butyl ether, diisobutyl ketone, methylcyclohexene Propyl ether, dihexyl ether, 1-hexanol, -Hexane, n-pentane, n-octane, diethyl ether, methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, n-butyl acetate, propylene glycol monoethyl ether, methyl pyruvate, ethyl pyruvate, 3-methoxy Methyl propionate, methyl ethyl 3-ethoxypropionate, ethyl 3-methoxypropionate, 3-ethoxypropionic acid, 3-methoxypropionic acid, propyl 3-methoxypropionate, butyl 3-methoxypropionate, 1-methoxy-2 -Propanol, 1-ethoxy-2-propanol, 1-butoxy-2-propanol, 2-butoxy-1-propanol, 2,6-dimethyl-4-heptanol, 1-phenoxy-2-propanol, propylene glycol monoacetate, propylene Glycol diacetate, propylene glycol-1-monomethyl ether-2-acetate, propylene glycol-1-monoethyl ether-2-acetate, dipropylene glycol, 2- (2-ethoxypropoxy) propanol, lactate methyl ester, lactate ethyl ester And solvents having a low surface tension such as lactic acid n-propyl ester, lactic acid n-butyl ester, and lactyl isoamyl ester.
These poor solvents may be used alone or in combination. When the above solvent is used, it is preferably 5 to 80% by mass, more preferably 20 to 60% by mass, based on the total solvent contained in the liquid crystal aligning agent.

Examples of compounds that improve film thickness uniformity and surface smoothness include fluorine-based surfactants, silicone-based surfactants, and nonionic surfactants.
More specifically, for example, F-top EF301, EF303, EF352 (manufactured by Tochem Products), MegaFuck F171, F173, R-30 (manufactured by Dainippon Ink), Florard FC430, FC431 (manufactured by Sumitomo 3M) Asahi Guard AG710, Surflon S-382, SC101, SC102, SC103, SC104, SC105, SC106 (manufactured by Asahi Glass Co., Ltd.). The use ratio of these surfactants is preferably 0.01 to 2 parts by mass, more preferably 0.01 to 1 part by mass with respect to 100 parts by mass of the resin component contained in the liquid crystal aligning agent.

Specific examples of the compound for improving the adhesion between the liquid crystal alignment film and the substrate include the following functional silane-containing compounds and epoxy group-containing compounds.
For example, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 2-aminopropyltrimethoxysilane, 2-aminopropyltriethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-ureidopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, N-ethoxycarbonyl-3-aminopropyltrimethoxysilane, N-ethoxy Carbonyl-3-aminopropyltriethoxysilane, N-triethoxysilylpropyltriethylenetriamine, N-trimethoxysilylpropyltriethylenetriamine, 10-trimethoxysilyl-1,4,7-triazadecane, 10-to Ethoxysilyl-1,4,7-triazadecane, 9-trimethoxysilyl-3,6-diazanonyl acetate, 9-triethoxysilyl-3,6-diazanonyl acetate, N-benzyl-3-aminopropyltri Methoxysilane, N-benzyl-3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltriethoxysilane, N-bis (oxyethylene) -3-amino Propyltrimethoxysilane, N-bis (oxyethylene) -3-aminopropyltriethoxysilane, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether , Polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerin diglycidyl ether, 2,2-dibromoneopentyl glycol diglycidyl ether, 1,3,5,6-tetra Glycidyl-2,4-hexanediol, N, N, N ′, N ′,-tetraglycidyl-m-xylenediamine, 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, N, N, N Examples include ', N',-tetraglycidyl-4,4'-diaminodiphenylmethane.

Furthermore, in addition to improving the adhesion between the substrate and the film, it is preferable to contain the following phenoplast type additives for the purpose of preventing electrical characteristics from being deteriorated by the backlight. Specific phenoplast type additives are shown below.

When using a compound that improves the adhesion to the substrate, the amount used is preferably 0.1 to 30 parts by weight, more preferably 1 to 20 parts by weight, based on 100 parts by weight of the resin component. is there. If the amount used is less than 0.1 parts by mass, the effect of improving the adhesion cannot be expected, and if it exceeds 30 parts by mass, the orientation of the liquid crystal may deteriorate.
In addition to the above, the liquid crystal aligning agent of the present invention may be a dielectric or conductive material for the purpose of changing the electrical properties such as dielectric constant and conductivity of the liquid crystal aligning film as long as the effects of the present invention are not impaired. Furthermore, a crosslinkable compound or the like for the purpose of increasing the hardness and density of the liquid crystal alignment film may be added.

<Liquid crystal alignment film and liquid crystal display element>
The liquid crystal aligning agent of the present invention can be applied as a liquid crystal alignment film without applying an alignment treatment in a vertical alignment application or the like after being applied on a substrate and baked and then subjected to an alignment treatment by rubbing treatment or light irradiation. In this case, the substrate to be used is not particularly limited as long as it is a highly transparent substrate, and a glass substrate, an acrylic substrate, a polycarbonate substrate such as a polycarbonate substrate, or the like can be used. In addition, it is preferable to use a substrate on which an ITO electrode or the like for driving liquid crystal is formed from the viewpoint of simplification of the process. In the reflective liquid crystal display element, an opaque material such as a silicon wafer can be used as long as only one substrate is used. In this case, a material that reflects light, such as aluminum, can also be used.
The application method of the liquid crystal aligning agent is not particularly limited, but industrially, it is generally performed by a method such as screen printing, offset printing, flexographic printing, or inkjet. Other coating methods include dip, roll coater, slit coater, spinner and the like, and these may be used depending on the purpose.

Firing after applying the liquid crystal aligning agent on the substrate can be carried out by a heating means such as a hot plate at 50 to 300 ° C., preferably 80 to 250 ° C., and the solvent can be evaporated to form a coating film. If the thickness of the coating film formed after baking is too thick, it is disadvantageous in terms of power consumption of the liquid crystal display element, and if it is too thin, the reliability of the liquid crystal display element may be lowered. The thickness is preferably 10 to 100 nm. When the liquid crystal is horizontally or tilted, the fired coating film is treated by rubbing or irradiation with polarized ultraviolet rays.
The liquid crystal display element of the present invention is a liquid crystal display element obtained by obtaining a substrate with a liquid crystal alignment film from the liquid crystal aligning agent of the present invention by the method described above, and then preparing a liquid crystal cell by a known method.

If an example of liquid crystal cell production is given, prepare a pair of substrates on which a liquid crystal alignment film is formed, spread spacers on the liquid crystal alignment film of one substrate, so that the liquid crystal alignment film surface is on the inside, Examples include a method of bonding the other substrate and injecting liquid crystal under reduced pressure, or a method of bonding a substrate after sealing the liquid crystal on the liquid crystal alignment film surface on which spacers are dispersed, and sealing. The thickness of the spacer is preferably 1 to 30 μm, more preferably 2 to 10 μm.

Hereinafter, examples will be given to describe the present invention more specifically, but the interpretation of the present invention is not limited to these examples. The abbreviations used in the examples and the method of property evaluation are as follows.

<Organic solvent>
NMP: N-methyl-2-pyrrolidone BCS: Butyl cellosolve <Additive>
LS-4668: 3-glycidoxypropyltriethoxysilane

<Viscosity measurement>
The viscosity of the solution was measured using an E-type viscometer TVE-22H (manufactured by Toki Sangyo Co., Ltd.) with a sample amount of 1.1 mL and a cone rotor TE-1 (1 ° 34 ′, R24) at a temperature of 25 ° C. .

<Production of liquid crystal display element>
First, a substrate with electrodes was prepared. The substrate is a glass substrate having a rectangular shape of 30 mm length × 35 mm width and a thickness of 0.7 mm. On the substrate, an IZO electrode having a solid pattern constituting a counter electrode as a first layer is formed. On the counter electrode of the first layer, a SiN (silicon nitride) film formed by the CVD method is formed as the second layer. The second layer SiN film has a thickness of 500 nm and functions as an interlayer insulating film. On the second SiN film, a comb-like pixel electrode formed by patterning an IZO film as the third layer is arranged to form two pixels, a first pixel and a second pixel. ing. The size of each pixel is 10 mm long and about 5 mm wide. At this time, the first-layer counter electrode and the third-layer pixel electrode are electrically insulated by the action of the second-layer SiN film.

The pixel electrode of the third layer has a comb-like shape configured by arranging a plurality of “bow” -shaped electrode elements having a bent central portion. The width in the short direction of each electrode element is 3 μm, and the distance between the electrode elements is 6 μm. The pixel electrode forming each pixel is formed by arranging a plurality of bent “bow” -shaped electrode elements at the center, so the shape of each pixel is not rectangular but is the same as that of the electrode element. It has a shape that resembles a bold “Kugi” that bends in part. Each pixel is divided into upper and lower portions with a central bent portion as a boundary, and has a first region on the upper side of the bent portion and a second region on the lower side.

When the first region and the second region of each pixel are compared, the formation directions of the electrode elements of the pixel electrodes constituting them are different. That is, when the rubbing direction of the liquid crystal alignment film described later is used as a reference, the electrode element of the pixel electrode is formed to form an angle of + 10 ° (clockwise) in the first region of the pixel, and the pixel in the second region of the pixel. The electrode elements of the electrode are formed so as to form an angle of −10 ° (clockwise). As a result, in the first region and the second region of each pixel, the direction of the rotation operation (in-plane switching) of the liquid crystal induced by the voltage application between the pixel electrode and the counter electrode is in the substrate plane. It is comprised so that it may become a mutually reverse direction.

Next, after the liquid crystal aligning agent is filtered through a filter having a pore diameter of 1.0 μm, an ITO film is formed on the back surface as the prepared substrate with electrodes and a counter substrate, and a columnar spacer having a height of 4 μm is provided. Each glass substrate was spin coated. Subsequently, after drying on an 80 degreeC hotplate for 2 minutes, the polyimide film with a film thickness of 60 nm was obtained on each board | substrate by baking at 230 degreeC for 20 minutes. The polyimide film is rubbed with a rayon cloth in a predetermined rubbing direction (roll diameter 120 mm, rotation speed 500 rpm, moving speed 30 mm / sec, pushing amount 0.3 mm), and then irradiated with ultrasonic waves in pure water for 1 minute. And dried at 80 ° C. for 10 minutes to obtain a liquid crystal alignment film.

Using the obtained two types of substrates with liquid crystal alignment film, the rubbing directions are combined so that they are antiparallel, the periphery is sealed leaving the liquid crystal injection port, and an empty cell with a cell gap of 3.5 μm is formed. Produced. A liquid crystal (MLC-3019, manufactured by Merck & Co., Inc.) was vacuum-injected into the empty cell at room temperature, and the injection port was sealed to obtain an anti-parallel alignment liquid crystal cell. The obtained liquid crystal cell constitutes an FFS mode liquid crystal display element. Thereafter, the obtained liquid crystal cell was heated at 120 ° C. for 1 hour and allowed to stand overnight before being used for each evaluation.

<Evaluation of liquid crystal alignment>
Using the liquid crystal cell obtained above, an AC voltage of 10 VPP was applied for 168 hours at a frequency of 30 Hz in a constant temperature environment of 60 ° C. Thereafter, the pixel electrode and the counter electrode of the liquid crystal cell were short-circuited and left as it was at room temperature for one day. After leaving, the liquid crystal cell is placed between two polarizing plates arranged so that the polarization axes are orthogonal, and the backlight is turned on with no voltage applied so that the brightness of the transmitted light is minimized. The arrangement angle of the liquid crystal cell was adjusted. Then, the rotation angle when the liquid crystal cell was rotated from the angle at which the second region of the first pixel became darkest to the angle at which the first region became darkest was calculated as an angle Δ. Similarly, for the second pixel, the second area was compared with the first area, and a similar angle Δ was calculated. Then, the average value of the angle Δ values of the first pixel and the second pixel was calculated as the angle Δ of the liquid crystal cell.
The smaller the angle Δ of the liquid crystal cell, the higher the liquid crystal alignment property of the liquid crystal alignment film.

<Gardner color number>
The obtained liquid crystal aligning agent was allowed to stand at room temperature for 24 hours, and then the Gardner color number was measured. The Gardner color number representing the color tone was measured based on Japanese Industrial Standard JIS K 0071-2. It means that the smaller the Gardner color number, the lighter the color of the obtained liquid crystal aligning agent.

(Synthesis Example 1)
A 50 mL four-necked flask equipped with a stirrer was placed in a nitrogen atmosphere, 0.73 g (2.58 mmol) of DA-1 and 2.54 g (10.4 mmol) of DA-4 were weighed, and 46.5 g of NMP was measured. In addition, it was dissolved by stirring while feeding nitrogen. While stirring this diamine solution, 2.71 g (12.4 mmol) of CA-2 was added, stirred for 2 hours at room temperature, and then stirred at 50 ° C. for 24 hours to obtain a polyamic acid solution (PAA-1, viscosity: 510.7 mPa · s) was obtained.

(Synthesis Example 2)
A 50 mL four-necked flask equipped with a stirrer was placed in a nitrogen atmosphere, 1.51 g (5.18 mmol) of DA-1 and 1.90 g (7.78 mmol) of DA-4 were weighed, and 54.6 g of NMP was added. The solution was stirred and dissolved while feeding nitrogen. While stirring this diamine solution, 2.71 g (12.4 mmol) of CA-2 was added, stirred for 2 hours at room temperature, and then stirred at 50 ° C. for 24 hours to obtain a polyamic acid solution (PAA-2, viscosity: 505.4 mPa · s) was obtained.

(Synthesis Example 3)
A 50 mL four-necked flask equipped with a stirrer was placed in a nitrogen atmosphere, 0.73 g (2.58 mmol) of DA-1, 2.22 g (9.09 mmol) of DA-4, and 0.724 g of DA-6 ( 1.30 mmol) was weighed and 46.5 g of NMP was added, and dissolved by stirring while feeding nitrogen. While stirring this diamine solution, 2.71 g (12.4 mmol) of CA-2 was added, stirred for 2 hours at room temperature, and then stirred at 50 ° C. for 24 hours to obtain a polyamic acid solution (PAA-3, viscosity: 505.4 mPa · s) was obtained.

(Synthesis Example 4)
A 50 mL four-necked flask equipped with a stirrer was placed in a nitrogen atmosphere, 0.73 g (2.58 mmol) of DA-1 and 2.98 g (10.4 mmol) of DA-5 were weighed, and 47.4 g of NMP was measured. In addition, it was dissolved by stirring while feeding nitrogen. While stirring this diamine solution, 2.71 g (12.4 mmol) of CA-2 was added, stirred for 2 hours at room temperature, then stirred at 50 ° C. for 24 hours to obtain a polyamic acid solution (PAA-4, viscosity: 525.3 mPa · s) was obtained.

(Synthesis Example 5)
A 50 mL four-necked flask equipped with a stirrer was placed in a nitrogen atmosphere, 1.51 g (5.21 mmol) of DA-1 and 2.23 g (7.79 mmol) of DA-5 were weighed, and 47.7 g of NMP was measured. In addition, it was dissolved by stirring while feeding nitrogen. While stirring the diamine solution, 2.71 g (12.4 mmol) of CA-2 was added, and the mixture was stirred for 2 hours at room temperature and then stirred at 50 ° C. for 24 hours to obtain a polyamic acid solution (PAA-5, viscosity: 510 .4 mPa · s) was obtained.

(Synthesis Example 6)
A 50 mL four-necked flask equipped with a stirrer was placed in a nitrogen atmosphere, 0.71 g (2.60 mmol) of DA-1, 2.60 g (9.08 mmol) of DA-5, and 0.724 g of DA-6 ( 1.30 mmol) was weighed, 50.0 g of NMP was added, and the mixture was stirred and dissolved while feeding nitrogen. While stirring the diamine solution, 2.71 g (12.4 mmol) of CA-2 was added, and the mixture was stirred for 2 hours at room temperature and then stirred at 50 ° C. for 24 hours to obtain a polyamic acid solution (PAA-6, viscosity: 498.1 mPa · s) was obtained.

(Comparative Synthesis Example 1)
A 50 mL four-necked flask equipped with a stirrer was placed in a nitrogen atmosphere, 2.79 g (14.0 mmol) of DA-3 was weighed, 47.1 g of NMP was added, and the mixture was stirred and dissolved while feeding nitrogen. While stirring this diamine solution, 2.44 g (12.4 mmol) of CA-1 was added and stirred at 15 ° C. for 2 hours to obtain a polyamic acid solution (PAA-7, viscosity: 121.1 mPa · s). It was.

(Comparative Synthesis Example 2)
A 50 mL four-necked flask equipped with a stirrer was placed in a nitrogen atmosphere, 0.53 g (2.60 mmol) of DA-3 and 2.51 g (10.3 mmol) of DA-4 were weighed, and 42.3 g of NMP was added. The solution was stirred and dissolved while feeding nitrogen. While stirring this diamine solution, 2.71 g (12.4 mmol) of CA-2 was added, and the mixture was stirred for 2 hours at room temperature and then stirred at 50 ° C. for 24 hours to obtain a polyamic acid solution (PAA-8, viscosity: 531.5 mPa · s) was obtained.

(Comparative Synthesis Example 3)
A 50 mL four-necked flask equipped with a stirrer was placed in a nitrogen atmosphere, 1.03 g (5.21 mmol) of DA-3 and 1.91 g (7.82 mmol) of DA-4 were weighed, and 41.4 g of NMP was added. The solution was stirred and dissolved while feeding nitrogen. While stirring this diamine solution, 2.71 g (12.4 mmol) of CA-2 was added, and the mixture was stirred for 2 hours at room temperature and then stirred at 50 ° C. for 24 hours to obtain a polyamic acid solution (PAA-9, viscosity: 542.2 mPa · s) was obtained.

(Comparative Synthesis Example 4)
A 50 mL four-necked flask equipped with a stirrer was placed in a nitrogen atmosphere, 0.51 g (2.56 mmol) of DA-3 and 2.97 g (10.4 mmol) of DA-5 were weighed, and 47.2 g of NMP was added. The solution was stirred and dissolved while feeding nitrogen. While stirring this diamine solution, 2.71 g (12.4 mmol) of CA-2 was added, stirred for 2 hours at room temperature, and then stirred at 50 ° C. for 24 hours to obtain a polyamic acid solution (PAA-10, viscosity: 547.1 mPa · s) was obtained.

(Comparative Synthesis Example 5)
A 50 mL four-necked flask equipped with a stirrer was placed in a nitrogen atmosphere, 0.53 g (2.56 mmol) of DA-3 and 2.97 g (10.4 mmol) of DA-5 were weighed, and 47.2 g of NMP was added. The solution was stirred and dissolved while feeding nitrogen. While stirring this diamine solution, 2.71 g (12.4 mmol) of CA-2 was added, stirred for 2 hours at room temperature, and then stirred at 50 ° C. for 24 hours to obtain a polyamic acid solution (PAA-11, viscosity: 547.1 mPa · s) was obtained.

(Comparative Synthesis Example 6)
A 50 mL (liter) four-necked flask equipped with a stirrer is placed in a nitrogen atmosphere, 3.29 g (11.0 mmol) of DA-1 is weighed, 46.1 g of NMP is added, and dissolved by stirring while feeding nitrogen. It was. While stirring this diamine solution, 1.91 g (9.7 mmol) of CA-1 was added and stirred at 15 ° C. for 2 hours to obtain a polyamic acid solution (PAA-12, viscosity: 121.1 mPa · s). It was.

(Comparative Synthesis Example 7)
A 50 mL four-necked flask equipped with a stirrer was placed in a nitrogen atmosphere, 2.77 g (13.0 mmol) of DA-2 was weighed, 46.1 g of NMP was added, and dissolved by stirring while feeding nitrogen. While stirring this diamine solution, 2.34 g (11.9 mmol) of acid dianhydride (CA-1) was added and stirred at 15 ° C. for 2 hours, and then a polyamic acid solution (PAA-13 viscosity: 110.4 mPas). Obtained s).

<Examples 1 to 6 and Comparative Examples 1 to 7>
24.0 g of each of 10 to 12% polyamic acid solutions PAA-1 to PAA13 obtained in Synthesis Examples 1 to 6 and Comparative Synthesis Examples 1 to 7 were fractionated, and 5% of NMP was added to each. .6 g, 8.00 g of BCS, and 2.4 g of a mixed solution containing 1% by weight of LS-4668 were added with stirring, and then stirred at room temperature for 2 hours. To (AL-13).

<Evaluation>
For each of the liquid crystal aligning agents (AL-1) to (AL-13) of Examples 1 to 6 and Comparative Examples 1 to 7 obtained above, the liquid crystal orientation and Gardner color number described above were evaluated. went. The results are shown in Table 1. In Table 1, the Gardner color number “−” means unmeasured.

The liquid crystal aligning agent of the present invention is used in a wide range of fields such as large liquid crystal display elements that require high definition and low cost, and mobile liquid crystal display elements such as smartphones and mobile phones.
The entire contents of the specification, claims, drawings, and abstract of Japanese Patent Application No. 2016-168461 filed on August 30, 2016 are cited herein as disclosure of the specification of the present invention. Incorporate.

Claims (8)

From the group consisting of a polyamic acid obtained by reaction of a diamine component containing a diamine having a structure represented by the following formula [1] and a tetracarboxylic dianhydride component, and a polyimide obtained by imidizing the polyamic acid. A liquid crystal aligning agent comprising at least one polymer selected.

(In the formula, A represents a heat-eliminable group that is replaced with a hydrogen atom by heating at a temperature of 150 to 300 ° C. The hydrogen atom of the benzene ring is an alkyl group or alkoxy group having 1 to 5 carbon atoms, or a halogen group. (* Represents a bond.) 2. The liquid crystal aligning agent according to claim 1, wherein the thermally leaving group is a tert-butoxycarbonyl group or a 9-fluorenylmethoxycarbonyl group. The liquid crystal aligning agent according to claim 1 or 2, wherein the diamine having the structure represented by the formula [1] is a diamine represented by any of the following formulas. Boc in the formula represents a tert-butoxycarbonyl group.

The liquid crystal aligning agent according to any one of claims 1 to 3, wherein a content of the diamine having a structure represented by the formula [1] in the diamine component is 5 to 95 mol%. The liquid crystal aligning agent according to any one of claims 1 to 4, wherein the tetracarboxylic dianhydride component is a compound represented by the following formula [7].

(In the formula, Z ₁ is a tetravalent organic group having 4 to 13 carbon atoms and has an aromatic cyclic hydrocarbon group.) 6. The liquid crystal aligning agent according to claim 5, wherein Z ₁ is any one of structures represented by any of the following formulas [7a] to [7k].

A liquid crystal alignment film obtained from the liquid crystal aligning agent according to any one of claims 1 to 6. A liquid crystal display device comprising the liquid crystal alignment film according to claim 7.