JP6638398B2 - Novel liquid crystal alignment agent, liquid crystal alignment film, and liquid crystal display device - Google Patents

Description

  The present invention relates to a novel liquid crystal aligning agent, a novel diamine useful as a raw material of a polymer used in the liquid crystal aligning agent, a polyimide precursor obtained using the diamine, and a polyimide.

2. Description of the Related Art A liquid crystal display device has been widely used as a display unit of a personal computer, a mobile phone, a television receiver, and the like. A lateral electric field method such as an IPS (In-Plane-Switching) method, an FFS (Fringe Field Switching) method, or the like is known.
Generally, the horizontal electric field method, in which an electrode is formed on only one side of the substrate and an electric field is applied in a direction parallel to the substrate, is compared with the conventional vertical electric field method, in which a voltage is applied to the electrodes formed on the upper and lower substrates to drive the liquid crystal. Is known as a liquid crystal display device having a wide viewing angle characteristic and capable of high quality display. As a method for aligning the liquid crystal in a certain direction, there is a method of performing a so-called rubbing treatment in which a polymer film such as polyimide is formed on a substrate, and the surface is rubbed with a cloth, and has been widely used industrially. Was.

  Conventional problems include a voltage holding ratio and accumulation of electric charge by a DC voltage component applied from an active matrix structure. When the electric charge is accumulated in the liquid crystal display element, it disturbs the alignment of the liquid crystal and affects the display as an afterimage, and significantly lowers the display quality of the liquid crystal display element. Alternatively, when driving is performed in a state in which electric charges are accumulated, immediately after driving, liquid crystal molecules are not normally controlled, and flicker occurs.

  Various proposals have been made for polyimide-based liquid crystal alignment films in order to meet the above requirements. For example, a liquid crystal alignment film containing a tertiary amine having a specific structure in addition to a polyamic acid or an imide group-containing polyamic acid as a liquid crystal alignment film having a short time until an afterimage generated by a DC voltage disappears (patented) Document 1) and a liquid crystal aligning agent containing a soluble polyimide containing a specific diamine having a pyridine skeleton or the like as a raw material (see Patent Document 2) have been proposed.

Patent Document 3 discloses a liquid crystal aligning agent containing a polyimide containing a specific diamine as a liquid crystal aligning agent for obtaining a liquid crystal aligning film excellent in light resistance of voltage holding ratio, high temperature and high humidity resistance, reworkability and printability. Have been.
Patent Document 4 discloses a specific diamine and an aromatic tetracarboxylic acid derivative as means for forming a liquid crystal alignment film having excellent liquid crystal alignment properties, rubbing resistance, and light transmittance, and effective for reducing an afterimage in a wide temperature range. There is disclosed a liquid crystal aligning agent characterized by including.
As a means for obtaining a liquid crystal alignment film having a high liquid crystal alignment property and a low tilt alignment angle, Patent Document 5 discloses a liquid crystal alignment treatment agent containing a polyimide precursor containing a specific diamine.

  Recently, with higher definition, higher display quality than before has been required, and the problems of voltage holding ratio and charge accumulation have come to appear more remarkably. In particular, in the liquid crystal display element of the horizontal electric field type, since the electrode portion formed in the substrate is small, if the voltage holding ratio of the liquid crystal alignment film is weak, a sufficient voltage is not applied to the liquid crystal, and the display contrast is reduced. In addition, compared to the vertical electric field method, the distance between the pixel electrode and the common electrode is short, so that a strong electric field acts on the alignment film and the liquid crystal layer, and these disadvantages are likely to be remarkable. There is a point. Further, in a method such as an IPS method or an FFS driving method in which liquid crystal molecules that are aligned parallel to a substrate are driven by a lateral electric field, stability of liquid crystal alignment is also important. If the stability of the alignment is poor, the liquid crystal will not return to the initial state when the liquid crystal is driven for a long time, causing a decrease in contrast, an afterimage, or burn-in. Further, in a substrate having a large step, higher rubbing resistance is required.

Japanese Patent Application Laid-Open No. 9-316200 JP-A-10-104633 JP 2013-152421 A International Publication WO2013 / 062115 pamphlet Japanese Patent Laid-Open No. Hei 10-123532

As a method of aligning the liquid crystal, rubbing treatment is widely used industrially, but depending on the liquid crystal alignment film used, a phenomenon in which the rubbing direction does not match the alignment direction of the liquid crystal, that is, a so-called twist angle may occur. That is, in the horizontal electric field element, black display is shown in a state where no voltage is applied. However, due to this phenomenon, luminance increases even in a state where no voltage is applied, and as a result, display contrast decreases. There was a problem.
The present invention provides a liquid crystal having a high voltage holding ratio and a high rubbing resistance, capable of rapidly relaxing accumulated charges, and capable of suppressing a shift between the rubbing direction and the alignment direction of the liquid crystal, which is a problem particularly in a lateral electric field driving method. An object is to provide a liquid crystal alignment agent from which an alignment film can be obtained.

  The present inventors have conducted intensive studies, and as a result, obtained a polyimide precursor obtained by reacting a diamine component containing a diamine of the following formula (1) with a tetracarboxylic acid derivative component, and ring-closing the polyimide precursor. It has been found that the above object can be achieved by a liquid crystal aligning agent containing a polymer selected from the group consisting of polyimides, and the present invention has been accomplished.

(Ｒ_１は水素、又は１価の有機基を表す。Ｑ_１は炭素数１乃至５のアルキレンを表す。Cyはアゼチジン、ピロリジン、ピペリジン又はヘキサメチレンイミンからなる脂肪族へテロ環を表す２価の基であり、これらの環部分に置換基が結合されていてもよい。Ｒ_２及びＲ_３は、それぞれ独立に１価の有機基である。ｑ及びｒは、それぞれ独立に０〜４の整数である。但し、ｑとｒの合計が２以上の場合、複数のＲ_２及びＲ_３は、上記定義を有する。)The gist of the present invention is as follows.
1. At least one member selected from the group consisting of a polyimide precursor obtained by reacting a diamine component containing a diamine of the following formula (1) with a tetracarboxylic acid derivative component, and a polyimide obtained by ring-closing the polyimide precursor A liquid crystal aligning agent characterized by containing a polymer.

(R ₁ represents hydrogen or a monovalent organic group. Q ₁ represents an alkylene having 1 to 5 carbon atoms. Cy represents a divalent aliphatic ring composed of azetidine, pyrrolidine, piperidine or hexamethyleneimine. Wherein R ₂ and R ₃ are each independently a monovalent organic group, and q and r are each independently 0 to 4 (In the case where the sum of q and r is 2 or more, a plurality of R ₂ and R ₃ have the above definition.)

(Ｘ_１はテトラカルボン酸誘導体に由来する４価の有機基であり、Ｙ_１は式（１）のジアミンに由来する２価の有機基であり、Ｒ_４は水素原子又は炭素数１〜５のアルキル基である。)
３．Ｘ１が、以下の式(Ｘ-1)〜(Ｘ-14)である、上記２に記載の液晶配向剤。

(Ｒ_５〜Ｒ_８は、それぞれ独立して、水素原子、ハロゲン原子、炭素数１〜６のアルキル基、炭素数２〜６のアルケニル基、炭素数２〜６のアルキニル基、又はフェニル基である。)
４．式（１）で表されるジアミンの割合は、全ジアミン成分１モルに対して、３０〜１００モル％である、上記１〜３のいずれかに記載の液晶配向剤。2. 2. The liquid crystal aligning agent according to the above 1, wherein the polyimide precursor is a polymer having a structural unit represented by the following formula (9).

(X ₁ is a tetravalent organic group derived from a tetracarboxylic acid derivative, Y ₁ is a divalent organic group derived from a diamine of the formula (1), and R ₄ is a hydrogen atom or a carbon atom having 1 to 5 carbon atoms. Is an alkyl group.)
3. 3. The liquid crystal aligning agent according to the above 2, wherein X1 has the following formula (X-1) to (X-14).

(R _{5 to} R ₈ are each independently 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, or a phenyl group. is there.)
4. The liquid crystal aligning agent according to any one of the above items 1 to 3, wherein the proportion of the diamine represented by the formula (1) is 30 to 100 mol% based on 1 mol of all diamine components.

(Ｒ_１は水素原子、メチル基、又はtert−ブトキシカルボニル基である。Ｒ_２は水素原子又はメチル基である。Ｑ_１は炭素数１〜５の直鎖アルキレンである。)5. 2. The liquid crystal aligning agent according to the above 1, wherein the diamine of the formula (1) is represented by the following formula (2).

(R ₁ is a hydrogen atom, a methyl group, or a tert-butoxycarbonyl group. R ₂ is a hydrogen atom or a methyl group. Q ₁ is a linear alkylene having 1 to 5 carbon atoms.)

6. A liquid crystal alignment film obtained by applying and firing the liquid crystal alignment agent according to any one of the above 1 to 5.
7. 7. The liquid crystal alignment film according to the item 6, wherein the film thickness after firing is 5 to 300 nm.
8. A liquid crystal display device comprising the liquid crystal alignment film according to the above item 6 or 7.

(式（１）中、Ｒ_１、Ｑ_１、Cy、Ｒ_２、Ｒ_３、ｑ、ｒは、上記１に定義した通りである。)9. A diamine represented by the formula (1).

(In the formula (1), R ₁ , Q ₁ , Cy, R ₂ , R ₃ , q, and r are as defined in the above 1.)

(Ｒ_１、Ｒ_２、Ｑ_１は上記５に定義した通りである。)
１３．上記９〜１２のいずれかに記載のジアミンを含有するジアミン成分とテトラカルボン酸誘導体成分を反応させて得られるポリイミド前駆体、及び該ポリイミド前駆体を閉環させて得られるポリイミドからなる群から選ばれる少なくとも１種の重合体。10. R ₁ is an alkyl group having 1 to 3 carbon atoms, a hydrogen atom, or a heat-labile group which is replaced by a hydrogen atom by heat; R ₂ and R ₃ each independently represent a methyl group, a trifluoromethyl group, a cyano group; Or a methoxy group.
11. The diamine according to the above 10, wherein R ₁ is a straight-chain alkyl group having 1 to 3 carbon atoms, a hydrogen atom, or a tert-butoxycarbonyl group, and Cy is a pyrrolidine or piperidine ring.
12. A diamine represented by the following formula (2).

(R _1, R ₂ and Q ₁ are as defined in 5 above.)
13. A polyimide precursor obtained by reacting a diamine component containing a diamine according to any of the above 9 to 12 with a tetracarboxylic acid derivative component, and a polyimide precursor obtained by ring-closing the polyimide precursor, selected from the group consisting of: At least one polymer.

According to the liquid crystal aligning agent of the present invention, the voltage holding ratio and the rubbing resistance are high, and the accumulated charges can be rapidly relaxed. A liquid crystal alignment film that can suppress the displacement can be obtained.
The liquid crystal alignment agent of the present invention contains at least one polymer selected from the group consisting of a polyimide precursor obtained by using the novel diamine of the present invention as a raw material, and a polyimide obtained by ring-closing the polyimide precursor.

<Polyimide precursor and polyimide>
The liquid crystal aligning agent of the present invention comprises a polyimide precursor obtained by reacting a diamine component containing a diamine of the following formula (1) with a tetracarboxylic acid derivative component, and a polyimide obtained by ring-closing the polyimide precursor. It contains at least one polymer selected from the group.

上記式（９）において、Ｘ_１はテトラカルボン酸誘導体に由来する４価の有機基であり、Ｙ_１は式（１）のジアミンに由来する２価の有機基であり、Ｒ_４は水素原子又は炭素数１〜５のアルキル基である。The polyimide precursor of the present invention is preferably a polymer containing a structural unit represented by the following formula (9).

In the above formula (9), X ₁ is a tetravalent organic group derived from a tetracarboxylic acid derivative, Y ₁ is a divalent organic group derived from a diamine of the formula (1), and R ₄ is a hydrogen atom. Or it is a C1-C5 alkyl group.

Ｒ_１は、水素又は１価の有機基を表し、好ましくは、水素原子、又は炭素数１〜３の直鎖アルキル基であり、より好ましくは水素原子、又はメチル基である。
また、Ｒ_１は、熱により脱離反応を生じ、水素原子に置き換わる保護基であってもよい。液晶配向剤の保存安定性の点から、この保護基は、室温においては脱離せず、好ましくは、８０℃以上、より好ましくは１００℃以上、特に好ましくは１５０〜２００℃で脱離し、水素原子になるのが好適である。例えば、１,１−ジメチル−２−クロロエトキシカルボニル基、１,１−ジメチル−２−シアノエトキシカルボニル基、tert−ブトキシカルボニル基等が挙げられ、好ましくはtert］−ブトキシカルボニル基である。1. Diamine

R ₁ represents hydrogen or a monovalent organic group, preferably a hydrogen atom or a straight-chain alkyl group having 1 to 3 carbon atoms, more preferably a hydrogen atom or a methyl group.
Further, R ₁ may be a protecting group which causes an elimination reaction by heat and replaces a hydrogen atom. From the viewpoint of storage stability of the liquid crystal aligning agent, this protecting group does not leave at room temperature, preferably 80 ° C. or higher, more preferably 100 ° C. or higher, particularly preferably 150 to 200 ° C., and a hydrogen atom It is preferred that Examples thereof include a 1,1-dimethyl-2-chloroethoxycarbonyl group, a 1,1-dimethyl-2-cyanoethoxycarbonyl group, a tert-butoxycarbonyl group, and the like, and a tert] -butoxycarbonyl group is preferable.

Q ₁ represents an alkylene group having 1 to 5 carbon atoms, and is preferably a straight-chain alkylene having 1 to 5 carbon atoms for convenience of synthesis. Cy is a divalent group representing an aliphatic heterocycle composed of azetidine, pyrrolidine, piperidine, or hexamethyleneimine, and azetidine, pyrrolidine, or piperidine is preferable from the viewpoint of ease of synthesis. Further, a substituent may be bonded to these ring portions.
R ₂ and R ₃ are each independently a monovalent organic group, and q and r are each independently an integer of 0 to 4. However, when the sum of q and r is 2 or more, a plurality of R ₂ and R ₃ have the above definition. For convenience of synthesis, R ₂ and R ₃ are preferably a methyl group.
The bonding position of the amino group in the benzene ring constituting the diamine is not limited, but the amino group may be in the 3-position or the 4-position with respect to the nitrogen atom on Cy, and the nitrogen may be bonded to Q ₁ and R _1. Preferably at the 3- or 4-position to the atom, at the 4-position to the nitrogen atom on Cy, and at the 4-position to the nitrogen atom to which Q ₁ and R ₁ bind. Is more preferred.

式（２）において、Ｒ_１は、水素原子、メチル基、又はtert−ブトキシカルボニル基である。Ｒ_２は、水素原子又はメチル基である。Ｑ_１は、炭素数１〜５の直鎖アルキレンである。The diamine represented by the above formula (1) of the present invention is preferably the following formula (2).

In the formula (2), R ₁ is a hydrogen atom, a methyl group, or a tert-butoxycarbonyl group. R ₂ is a hydrogen atom or a methyl group. Q ₁ is linear alkylene having 1 to 5 carbon atoms.

Specific examples of the diamine represented by the above formula (2) include, for example, diamines represented by the following formulas (2-1) to (2-10). In the following formula, Boc represents a tert-butoxycarbonyl group.

The method for producing the diamine represented by the formula (1) is not particularly limited, but preferred methods include the following production methods [1] and [2].
Manufacturing method [1]
A dinitro compound (3-3) is produced by reacting two or more equivalents of the nitro compound (3-1) with the aliphatic amine compound (3-2). Further, if necessary, a monovalent organic group consisting of R ₁ is introduced, and then the nitro group is reduced, whereby the desired diamine can be obtained. In addition, the nitro compound (3-1) and the aliphatic amine compound (3-2) can be easily obtained as commercial products.

In the nitro compound (3-1), X represents a halogen atom, and means F, Cl, Br or I atom. R ₂ is a monovalent organic group, q is an integer of 0 to 4, and when q is 2 or more, a plurality of R ₂ have the above definition.
When X is an F or Cl atom and the NO ₂ group is at the 2- or 4-position to X, the aryl halide is reacted with an aliphatic amine compound in the presence of a suitable base to obtain dinitrobenzene. The body (3-3) can be obtained.
The base used is, for example, an inorganic base such as sodium hydrogencarbonate, potassium hydrogencarbonate, potassium phosphate, sodium carbonate, potassium carbonate, lithium carbonate, cesium carbonate, etc .; trimethylamine, triethylamine, tripropylamine, triisopropylamine, tributylamine, diisopropyl Amines such as ethylamine, pyridine, quinoline and collidine; bases such as sodium hydride and potassium hydride can be used.

As for the solvent, any solvent that does not react with the raw materials can be used. For example, aprotic polar organic solvents (N, N-dimethylformamide (DMF), dimethylsulfoxide (DMSO), N, N-dimethylacetamide (DMAc), N-methyl-2-pyrrolidone (NMP), etc.), ethers (Diethyl ether (Et ₂ O), isopropyl ether (i-Pr ₂ O), tert-butyl methyl ether (TBME), cyclopentyl methyl ether (CPME), tetrahydrofuran (THF), dioxane, etc.), aliphatic hydrocarbons ( Pentane, hexane, heptane, petroleum ether, etc.), aromatic hydrocarbons (benzene, toluene, xylene, mesitylene, chlorobenzene, dichlorobenzene, nitrobenzene, tetralin, etc.), halogenated hydrocarbons (chloroform, dichloromethane, carbon tetrachloride) , Dichloroethane, etc.), lower fatty acid esters (methyl acetate, Butyl, butyl acetate, methyl propionate, etc.) and nitriles (acetonitrile, propionitrile, butyronitrile, etc.). These solvents can be appropriately selected in consideration of the easiness of the reaction and the like. In this case, the above-mentioned solvents can be used alone or in combination of two or more. In some cases, the solvent can be dehydrated and dried using a suitable dehydrating agent or desiccant, and used.

The reaction temperature can be selected from any temperature in the range from -100 ° C to the boiling point of the solvent used, but is preferably in the range of -50 to 150 ° C. The reaction time can be arbitrarily selected within the range of 0.1 to 1000 hours, but is preferably 0.1 to 100 hours.
The product may be purified by recrystallization, distillation, silica gel column chromatography or the like.
If X is a Br or I atom, the NO ₂ group may be at the _2- , 3-, or 4-position to X, containing a suitable metal catalyst and a ligand, and CN cross-coupling in the presence of a base. A dinitro compound can be obtained by using the reaction.

Examples of the metal catalyst include palladium acetate, palladium chloride, palladium chloride-acetonitrile complex, palladium-activated carbon, bis (dibenzylideneacetone) palladium, tris (dibenzylideneacetone) dipalladium, bis (acetonitrile) dichloropalladium, bis (benzo) Nitrile) dichloropalladium, CuCl, CuBr, CuI, CuCN and the like, but are not limited thereto.
Examples of ligands include triphenylphosphine, tri-o-tolylphosphine, diphenylmethylphosphine, phenyldimethylphosphine, 1,2-bis (diphenylphosphino) ethane, 1,3-bis (diphenylphosphino) propane , 1,4-bis (diphenylphosphino) butane, 1,1'-bis (diphenylphosphino) ferrocene, trimethylphosphite, triethylphosphite, triphenylphosphite, tri-tert-butylphosphine and the like. However, the present invention is not limited to these.
As examples of the base, the above-mentioned bases can be used.
The reaction solvent and reaction temperature are as described above.
The product may be purified by recrystallization, distillation, silica gel column chromatography or the like.

In the above reaction formula (4), a monovalent organic group consisting of R ₁ may be introduced into the dinitro compound (3-3) as needed.
In introducing R1, any compound capable of reacting with amines may be used, and examples thereof include acid halides, acid anhydrides, isocyanates, epoxies, oxetanes, aryl halides, and alkyl halides. . In addition, alcohols in which the hydroxyl group of alcohol is substituted with a leaving group such as Oms (mesyl group), OTf (triflate group), and OTs (tosyl group) can be used.

Methods for introducing a monovalent organic group consisting of R ₁ into the NH group include the following methods and the like, but are not particularly limited.
For example, there is a method in which an acid halide is reacted in the presence of a suitable base.
Examples of acid halides include acetyl chloride, propionyl chloride, methyl chloroformate, ethyl chloroformate, n-propyl chloroformate, i-propyl chloroformate, n-butyl chloroformate, i-butyl chloroformate, and t-chloroformate. Butyl, benzyl chloroformate, or 9-fluorenyl chloroformate.
As examples of the base, the above-mentioned bases can be used.
The reaction solvent and reaction temperature are as described above.

R ₁ may be introduced by reacting an acid anhydride with the NH group.
Examples of the acid anhydride include acetic anhydride, propionic anhydride, dimethyl dicarbonate, diethyl dicarbonate, di-tert-butyl dicarbonate, dibenzyl dicarbonate and the like.
A catalyst may be added to promote the reaction. For example, pyridine, collidine, N, N-dimethyl-4-aminopyridine and the like may be used. The amount of the catalyst is 0.0001 to 1 mol, preferably 0.0005 to 0.2 mol, based on the amount (1 mol) of the dinitro compound (3-3) used.
The reaction solvent and reaction temperature are as described above.
R ₁ may be introduced by reacting an isocyanate with the NH group.
Examples of isocyanates include methyl isocyanate, ethyl isocyanate, n-propyl isocyanate, phenyl isocyanate and the like.
The reaction solvent and reaction temperature are as described above.
R ₁ may be introduced by reacting an epoxy compound or an oxetane compound with the NH group.
Examples of epoxies and oxetanes include ethylene oxide, propylene oxide, 1,2-butylene oxide, trimethylene oxide and the like.
The reaction solvent and reaction temperature are as described above.

Alternatively, R ₁ may be introduced into the NH group by reacting a halogenated aryl compound in the presence of a metal catalyst, a ligand and a base.
Examples of aryl halides include iodobenzene, bromobenzene, chlorobenzene, and the like.
Examples of the metal catalyst include palladium acetate, palladium chloride, palladium chloride-acetonitrile complex, palladium-activated carbon, bis (dibenzylideneacetone) palladium, tris (dibenzylideneacetone) dipalladium, bis (acetonitrile) dichloropalladium, bis (benzo) Nitrile) dichloropalladium, CuCl, CuBr, CuI, CuCN and the like, but are not limited thereto.
Examples of ligands include triphenylphosphine, tri-o-tolylphosphine, diphenylmethylphosphine, phenyldimethylphosphine, 1,2-bis (diphenylphosphino) ethane, 1,3-bis (diphenylphosphino) propane , 1,4-bis (diphenylphosphino) butane, 1,1'-bis (diphenylphosphino) ferrocene, trimethylphosphite, triethylphosphite, triphenylphosphite, tri-tert-butylphosphine and the like. However, the present invention is not limited to these.
As examples of the base, the above-mentioned bases can be used.
The reaction solvent and reaction temperature are as described above.

R ₁ may be introduced into the NH group by reacting an alcohol in which a hydroxyl group of the alcohol is substituted with a leaving group such as OMs, OTf or OTs in the presence of a suitable base.
Examples of alcohols include methanol, ethanol, 1-propanol, etc., and OMs, OTf , OTs and other leaving groups can be obtained.
As examples of the base, the above-mentioned bases can be used.
The reaction solvent and reaction temperature are as described above.

An alkyl halide may be reacted in the presence of a suitable base to introduce R ₁ into the NH group.
Examples of the alkyl halides include methyl iodide, ethyl iodide, n-propyl iodide, methyl bromide, ethyl bromide, n-propyl bromide and the like.
Examples of the base include metal alkoxides such as potassium-tert-butoxide and sodium-tert-butoxide in addition to the above-mentioned bases.
The reaction solvent and reaction temperature are as described above.

Next, in the above reaction formula (5), the nitro group in the obtained dinitro compound (4-1) is reduced to obtain the desired diamine (5-1). For the reduction of the nitro group, palladium carbon powder, platinum carbon powder or the like can be used. The reduction reaction is performed under a hydrogen atmosphere under normal pressure or pressurized conditions.
The nitro group may be reduced using a metal such as Fe, Sn, or Zn, or a metal salt thereof together with a proton source. Further, the metal and the metal salt may be used alone or as a mixture of two or more.
Acids such as hydrochloric acid, ammonium salts such as ammonium chloride, and protic solvents such as methanol and ethanol can be used as the proton source.

The solvent may be any solvent that can withstand the environment under the reducing atmosphere, such as aprotic polar organic solvents (DMF, DMSO, DMAC, NMP, etc.), ethers (Et ₂ O, i-Pr ₂ O, TBME, CPME, THF, dioxane, etc.), aliphatic hydrocarbons (pentane, hexane, heptane, petroleum ether, etc.), aromatic hydrocarbons (benzene, toluene, xylene, mesitylene, chlorobenzene, dichlorobenzene, nitrobenzene, tetralin, etc.) , Lower fatty acid esters (methyl acetate, ethyl acetate, butyl acetate, methyl propionate, etc.), nitriles (acetonitrile, propionitrile, butyronitrile, etc.), alcohols (methanol, ethanol, 1-propanol, 2-propanol, 1 -Butanol, etc.) can be used.
These solvents can be appropriately selected in consideration of the easiness of the reaction and the like, and can be used alone or in combination of two or more. In some cases, the solvent can be dehydrated and dried using a suitable dehydrating agent or desiccant, and used.
The reaction temperature can be arbitrarily selected from the range of -100 ° C to the boiling point of the solvent used, but is preferably in the range of -50 to 150 ° C.
The reaction time can be arbitrarily selected within the range of 0.1 to 1000 hours, but is preferably 0.1 to 100 hours.
The product may be purified by recrystallization, distillation, silica gel column chromatography, activated carbon or the like.

Manufacturing method [2]
By reacting the nitro compound ((3-1) or (6-1)) with the aliphatic amine compound (6-2) protected with a protecting group, the nitro compound ((6-3) or (6-3) 6-4)) is obtained. Then, after deprotection, the following dinitro compound ((8-1) or (8-2)) is obtained by reacting with a nitro compound ((3-1) or (6-1)). . Further, if necessary, a monovalent organic group represented by R ₁ is introduced into the NH group by the same method as in the production method [1], and then the nitro group is reduced to obtain the desired diamine. Can be.
The nitro compound (6-1) and the aliphatic amine compound (6-2) protected with a protecting group can be easily obtained as commercial products.

In the following reaction formula (6), X, R ₂ and q are as described above, R ₃ is a monovalent organic group, r is an integer of 0 to 4, and when r is 2 or more, A plurality of R ₃ each independently have the above definition.
Pro represents a protecting group, acetyl, trifluoroacetyl, pivaloyl, tert-butoxycarbonyl, ethoxycarbonyl, isopropoxycarbonyl, 2,2,2-trichloroethoxycarbonyl, benzyloxycarbonyl, trimethylsilyl Group, triethylsilyl group, dimethylphenylsilyl group, tert-butyldimethylsilyl group, tert] -butyldiethylsilyl group, 9-fluorenylmethyloxycarbonyl group, phthaloyl group, allyloxycarbonyl group, p-toluenesulfonyl group, represents an o-nitrobenzenesulfonyl group or the like.
The nitro compound ((6-3) or (6-4)) is synthesized by using one or more equivalents of the nitro compound ((3-1) or (6-1)) in the production method [1]. It can be carried out in the same manner as in the reaction formula (3). The protecting group is preferably not deprotected under basic conditions, and a tert-butoxycarbonyl group is desirable from the viewpoint of ease of deprotection after the reaction and availability.

In the following reaction formula (7), the nitro compound ((6-3) or (6-4)) is deprotected to give an intermediate ((7-1) or (7-2)). ) Can be obtained.
The method for deprotecting the protecting group is not particularly limited, but the desired product can be obtained by neutralization after hydrolysis in the presence of an acid or a base.
Examples of the acid used include inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, and hydrobromic acid, and organic acids such as formic acid, acetic acid, oxalic acid, and trifluoroacetic acid.
Examples of the base to be used include inorganic bases such as sodium hydroxide, sodium hydrogen carbonate, potassium hydrogen carbonate, potassium phosphate, sodium carbonate, potassium carbonate, lithium carbonate, cesium carbonate, etc., trimethylamine, triethylamine, tripropylamine, triisopropylamine And organic amines such as tributylamine, diisopropylethylamine, pyridine, quinoline and collidine.
Alternatively, deprotection may be performed using a Lewis acid compound such as aluminum chloride or a trifluoroborane-diethyl ether complex. However, a debenzylation reaction under a hydrogen atmosphere is not preferable because an aromatic nitro group is reduced to an amino group.

As for the solvent, any solvent can be used as long as it does not hinder hydrolysis. For example, aprotic polar organic solvents (DMF, DMSO, DMAc, NMP, etc.), ethers (Et ₂ O, i-Pr ₂ O, TBME, CPME, THF, dioxane, etc.), aliphatic hydrocarbons (pentane, Hexane, heptane, petroleum ether, etc.), aromatic hydrocarbons (benzene, toluene, xylene, mesitylene, chlorobenzene, dichlorobenzene, nitrobenzene, tetralin, etc.), halogenated hydrocarbons (chloroform, dichloromethane, carbon tetrachloride, dichloroethane) ), Lower fatty acid esters (methyl acetate, ethyl acetate, butyl acetate, methyl propionate, etc.), nitriles (acetonitrile, propionitrile, butyronitrile, etc.), alcohols (methanol, ethanol, 1-propanol, 2-propanol) , 1-butanol, etc.) or water. These solvents can be appropriately selected in consideration of the easiness of the reaction and the like, and can be used alone or in combination of two or more.
In consideration of the use of a Lewis acid and the like, depending on the solvent, the solvent may be dehydrated and dried using an appropriate dehydrating agent or drying agent before use.
The reaction temperature can be arbitrarily selected from the range of -100 ° C to the boiling point of the solvent used, but is preferably in the range of -50 to 150 ° C.
The reaction time can be arbitrarily selected within the range of 0.1 to 1000 hours, but is preferably 0.1 to 100 hours.
The product may be purified by recrystallization, distillation, silica gel column chromatography or the like.

得られたジニトロ体(（８−１）、又は（８−２））へ、必要に応じて、Ｒ_１を導入する方法は、製法[1]の反応式（４）と同様の反応条件でよい。その後、ニトロ基を還元することで、目的のジアミンを得ることができる。
ジニトロ体の還元方法も、製法[1]の反応式（５）と同様の反応条件で実施すればよい。The reaction formula of the production method [1] using one or more equivalents of the nitro compound ((3-1) or (6-1)) with respect to the intermediate ((7-1) or (7-2)) A dinitro compound ((8-1) or (8-2)) can be obtained in the same manner as in (3) (reaction formula (8)).

The resulting dinitro product ((8-1), or (8-2)) to, if necessary, a method of introducing the R _1, the reaction formula of the process [1] (4) under the same reaction conditions as Good. Then, the target diamine can be obtained by reducing the nitro group.
The dinitro compound may be reduced under the same reaction conditions as in the reaction formula (5) of the production method [1].

2. Polyimide precursor and polyimide The polyimide precursor of the present invention is a polyimide precursor obtained by reacting a diamine component containing a diamine represented by the formula (1) with a tetracarboxylic acid derivative component. Here, the polyimide precursor is a polyamic acid or a polyamic acid ester.
Examples of the tetracarboxylic acid derivative include an acid dianhydride, a dicarboxylic diester, and a diester dicarboxylic chloride.
The polyamic acid is obtained by reacting a diamine component with an acid dianhydride, and the polyamic acid ester is obtained by reacting a diamine component with a dicarboxylic acid diester or diester dicarboxylic acid chloride.
The polyimide of the present invention is a polyimide obtained by ring-closing these polyimide precursors, and both are useful as a polymer for obtaining a liquid crystal alignment film.

  In the diamine component for obtaining the above-mentioned polyimide precursor, the content ratio of the diamine represented by the formula (1) is not limited. The proportion of the diamine represented by the formula (1) is preferably from 10 to 100 mol%, more preferably from 20 to 100 mol%, and still more preferably from 30 to 100 mol%, based on 1 mol of all diamine components. is there.

上記（９）式において、Ｘ_１はテトラカルボン酸誘導体に由来する４価の有機基であり、Ｙ_１は式（１）のジアミンに由来する２価の有機基であり、Ｒ_４は水素原子又は炭素数１〜５のアルキル基である。加熱によるイミド化のしやすさの点から、Ｒ_４は、水素原子、メチル基又はエチル基が好ましい。The polyimide precursor of the present invention is preferably a polymer containing a structural unit represented by the following formula (9).

In the above formula (9), X ₁ is a tetravalent organic group derived from a tetracarboxylic acid derivative, Y ₁ is a divalent organic group derived from the diamine of the formula (1), and R ₄ is a hydrogen atom Or it is a C1-C5 alkyl group. R ₄ is preferably a hydrogen atom, a methyl group or an ethyl group from the viewpoint of imidization by heating.

X ₁ is not particularly limited as long as it is a tetravalent organic group. In the polyimide precursor, X ₁ is 2 or more may be mixed.
If Specific examples of X _1, include the structures represented by the following formula (X-1) ~ (X -43). From the viewpoint of availability, (X-1) to (X-14) are more preferable.

上記式（Ｘ−１）におけるＲ_５〜Ｒ_８は、それぞれ独立して、水素原子、ハロゲン原子、炭素数１〜６のアルキル基、炭素数２〜６のアルケニル基、炭素数２〜６のアルキニル基、又はフェニル基である。Ｒ_５〜Ｒ_８が嵩高い構造である場合、液晶配向性を低下させる可能性があるため、水素原子、メチル基、又はエチル基がより好ましく、水素原子、又はメチル基が特に好ましい。

R _{5 to} R ₈ in the above formula (X-1) are each independently 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 or a phenyl group. When R _{5 to} R ₈ have a bulky structure, a hydrogen atom, a methyl group, or an ethyl group is more preferable, and a hydrogen atom or a methyl group is particularly preferable, since liquid crystal alignment may be reduced.

In addition, the polyimide precursor of the present invention may contain a structural unit represented by the following formula (10) in addition to the above formula (9) as long as the effects of the present invention are not impaired.

In the formula (10), R ₄ has the same definition as in the above formula (9). X ₂ is a tetravalent organic group, and has the same definition as X ₁ in the above formula (9), including preferred examples. Z ₁ and Z ₂ are each independently a hydrogen atom, an optionally substituted alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms or an alkynyl group having 2 to 10 carbon atoms. is there.
Specific examples of the alkyl group having 1 to 10 carbon atoms include methyl, ethyl, propyl, butyl, t-butyl, hexyl, octyl, decyl, cyclopentyl, cyclohexyl, bicyclohexyl, and the like. Is mentioned.

Examples of the alkenyl group having 2 to 10 carbon atoms include one in which one or more CH ₂ —CH ₂ present in the above alkyl group is replaced with CH ＝ CH. More specifically, vinyl group, allyl group, 1-propenyl group, isopropenyl group, 2-butenyl group, 1,3-butadienyl group, 2-pentenyl group, 2-hexenyl group, cyclopropenyl group, cyclopentenyl group And a cyclohexenyl group.
Examples of the alkynyl group having 2 to 10 carbon atoms include one in which one or more CH ₂ —CH ₂ present in the above alkyl group is replaced with C≡C. More specifically, examples include an ethynyl group, a 1-propynyl group, a 2-propynyl group, and the like.

The alkyl group having 1 to 10 carbon atoms, the alkenyl group having 2 to 10 carbon atoms, and the alkynyl group having 2 to 10 carbon atoms have a substituent within a range not exceeding 10 in total carbon atoms including the substituent. And a substituent may form a ring structure. Note that forming a ring structure with a substituent means that the substituents are bonded to each other or to a part of the parent skeleton to form a ring structure.
Examples of the substituent include a halogen group, a hydroxyl group, a thiol group, a nitro group, an aryl group, an organooxy group, an organothio group, an organosilyl group, an acyl group, an ester group, a thioester group, a phosphate ester group, an amide group, and an alkyl group. Group, alkenyl group, alkynyl group and the like.

In the polyimide precursor, generally, when a bulky structure is introduced, the reactivity of the amino group and the liquid crystal alignment may be reduced. Therefore, as Z ₁ and Z ₂ , a hydrogen atom or a An alkyl group having 1 to 5 carbon atoms is more preferable, and a hydrogen atom, a methyl group or an ethyl group is particularly preferable.

In the above formula (10), Y ₂ is a divalent organic group derived from a diamine component other than the formula (1), and its structure is not particularly limited. Specific examples of Y ₂ include the following formulas (Y-1) to (Y-114). Further, two or more diamine components may be used.

Among them, in order to obtain good liquid crystal alignment, it is preferable to use a diamine which forms a highly linear polyimide. Therefore, from the liquid crystal orientation point, _{Y 2} is, Y-7, Y-10 , Y-11, Y-12, Y-13, Y-21, Y-22, Y-23, Y-25, Y-26, Y-27, Y-41, Y-42, Y-43, Y-44, Y-45, Y-46, Y-48, Y-61, Y-63, Y-64, Y- 71, Y-72, Y-73, Y-74, Y-75 or Y-98.
The proportion of the diamine is preferably 40 to 100 mol%, more preferably 60 to 100 mol%, based on 1 mol of all diamine components.

When it is desired to increase the pretilt angle, it is preferable to use a long-chain alkyl group, an aromatic ring, an aliphatic ring, a steroid skeleton, or a diamine having a structure obtained by combining these in a side chain. In terms of pre-tilt angle, _{Y 2} is, Y-76, Y-77 , Y-78, Y-79, Y-80, Y-81, Y-82, Y-83, Y-84, Y-85 , Y-86, Y-87, Y-88, Y-89, Y-90, Y-91, Y-92, Y-93, Y-94, Y-95, Y-96 or Y-97. Is preferred. By adding these diamines in an amount of 1 to 50 mol%, more preferably 5 to 20 mol% of the total diamine components, an arbitrary pretilt angle can be developed.

3. Method for Producing Polyamic Acid Polyamic acid which is a polyimide precursor of the present invention can be obtained by reacting a diamine component containing the diamine of the present invention with a tetracarboxylic acid derivative component.
Specifically, it can be synthesized by reacting a tetracarboxylic dianhydride with a diamine in the presence of an organic solvent.
The organic solvent is not particularly limited as long as the generated polyamic acid can be dissolved. Specific examples include N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methylcaprolactam, dimethylsulfoxide, and γ-butyrolactone. When the solubility of the polyimide precursor is high, it is represented by methyl ethyl ketone, cyclohexanone, cyclopentanone, 4-hydroxy-4-methyl-2-pentanone or the following formulas (D-1) to (D-3). Organic solvent can be used.

式（Ｄ−１）中、Ｄ^１は炭素数１〜３のアルキル基を示し、式（Ｄ−２）中、Ｄ^２は炭素数１〜３のアルキル基を示し、式（Ｄ−３）中、Ｄ^３は炭素数１〜４のアルキル基を示す。
これらは単独で使用しても、混合して使用してもよい。さらには、単独ではポリアミック酸を溶解させない溶媒であっても、生成したポリアミック酸が析出しない範囲で、上記溶媒に混合して使用してもよい。また、有機溶媒中の水分は重合反応を阻害し、さらには生成したポリアミック酸を加水分解させる原因となるので、有機溶媒は、なるべく脱水乾燥させたものを用いることが好ましい。

In the formula (D-1), D ¹ represents an alkyl group having 1 to 3 carbon atoms, and in the formula (D-2), D ² represents an alkyl group having 1 to 3 carbon atoms; In the formula, D ³ represents an alkyl group having 1 to 4 carbon atoms.
These may be used alone or as a mixture. Furthermore, even a solvent which does not dissolve the polyamic acid alone may be used by mixing with the above solvent as long as the generated polyamic acid does not precipitate. Further, since water in the organic solvent inhibits the polymerization reaction and further causes hydrolysis of the generated polyamic acid, it is preferable to use an organic solvent which is dehydrated and dried as much as possible.

As a method of mixing the diamine component and the tetracarboxylic dianhydride in the organic solvent, a solution obtained by dispersing or dissolving the diamine in the organic solvent is stirred, and the tetracarboxylic dianhydride is directly dispersed in the organic solvent. Alternatively, a method of dissolving and adding, a method of dispersing or dissolving tetracarboxylic dianhydride in an organic solvent, a method of adding diamine, alternately or simultaneously adding tetracarboxylic dianhydride and diamine to an organic solvent. Addition methods and the like are mentioned, and any of these methods may be used.
The temperature at the time of synthesizing the polyamic acid can be selected from any temperature of -20 to 150 ° C, but is preferably in the range of -5 to 100 ° C, and more preferably 0 to 80 ° C.
The reaction time can be arbitrarily selected within a range longer than the time during which the polymerization of the polyamic acid is stabilized, but is preferably 30 minutes to 24 hours, more preferably 1 to 12 hours.

The reaction can be performed at any concentration, but if the concentration of the raw material diamine component and tetracarboxylic dianhydride is too low, it becomes difficult to obtain a high molecular weight polymer, and if the concentration is too high, the reaction solution Is too high and uniform stirring becomes difficult, so the amount is preferably 1 to 50% by mass, more preferably 5 to 20% by mass. The initial stage of the reaction may be performed at a high concentration, and then an organic solvent may be added.
In the synthesis reaction of the polyamic acid, the ratio of the number of moles of the tetracarboxylic dianhydride to the number of moles of the diamine component is preferably 0.8 to 1.2. As in the ordinary polycondensation reaction, the closer the molar ratio is to 1.0, the higher the molecular weight of the generated polyamic acid.

The polyamic acid obtained as described above can be recovered by precipitating a polymer by injecting it into a poor solvent while stirring the reaction solution well. In addition, by performing precipitation several times, washing with a poor solvent, and drying at room temperature or by heating, a purified polyamic acid powder can be obtained.
The poor solvent is not particularly limited, but includes water, methanol, ethanol, 2-propanol, hexane, butyl cellosolve, acetone, toluene and the like, and water, methanol, ethanol, 2-propanol and the like are preferable.

4. Production of polyamic acid ester The polyamic acid ester which is the polyimide precursor of the present invention can be produced by the following method [1], [2] or [3].

[1] When Producing from Polyamic Acid The polyamic acid ester can be produced by esterifying the polyamic acid produced as described above.
Specifically, by reacting a polyamic acid and an esterifying agent in the presence of an organic solvent at -20 to 150 ° C, preferably 0 to 50 ° C, for 30 minutes to 24 hours, preferably for 1 to 4 hours. Can be manufactured.
As the esterifying agent, those which can be easily removed by purification are preferable, and N, N-dimethylformamide dimethyl acetal, N, N-dimethylformamide diethyl acetal, N, N-dimethylformamide dipropyl acetal, N, N-dimethylformamide Dineopentyl butyl acetal, N, N-dimethylformamide di-t-butyl acetal, 1-methyl-3-p-tolyltriazene, 1-ethyl-3-p-tolyltriazene, 1-propyl-3-p -Tolyltriazene, 4- (4,6-dimethoxy-1,3,5-triazin-2-yl) -4-methylmorpholinium chloride and the like. The addition amount of the esterifying agent is preferably 2 to 6 molar equivalents per 1 mol of the repeating unit of the polyamic acid.

Examples of the organic solvent include N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone or γ-butyrolactone, N, N-dimethylformamide, N, N-dimethylacetamide, dimethylsulfoxide or 1,3-dimethyl- And imidazolidinone. When the solubility of the polyimide precursor in the solvent is high, methyl ethyl ketone, cyclohexanone, cyclopentanone, 4-hydroxy-4-methyl-2-pentanone, or any of the above formulas (D-1) to (D-3) ) Can be used.
The solvents may be used alone or as a mixture. Furthermore, even if the solvent does not dissolve the polyimide precursor, the solvent may be mixed with the solvent as long as the generated polyimide precursor does not precipitate. Further, since water in the solvent inhibits the polymerization reaction and further causes hydrolysis of the produced polyimide precursor, it is preferable to use a solvent that has been dehydrated and dried.
The solvent used in the above reaction is preferably N, N-dimethylformamide, N-methyl-2-pyrrolidone, or γ-butyrolactone from the viewpoint of solubility of the polymer. These solvents may be used alone or in combination of two or more. Is also good. The concentration at the time of production is preferably from 1 to 30% by mass, more preferably from 5 to 20% by mass, from the viewpoint that precipitation of the polymer hardly occurs and a high molecular weight substance is easily obtained.

[2] When Produced by Reaction of Tetracarboxylic Acid Diester Dichloride with Diamine The polyamic acid ester can be produced from a tetracarboxylic diester dichloride and a diamine component containing the diamine of the present invention.
Specifically, tetracarboxylic diester dichloride and diamine, in the presence of a base and an organic solvent, at -20 to 150 ° C, preferably at 0 to 50 ° C, for 30 minutes to 24 hours, preferably for 1 to 4 hours. It can be produced by reacting.
As the base, pyridine, triethylamine, 4-dimethylaminopyridine and the like can be used, but pyridine is preferable because the reaction proceeds gently. The amount of the base to be added is preferably 2 to 4 moles, more preferably 2 to 3 moles with respect to the tetracarboxylic diester dichloride from the viewpoint of easy removal and high molecular weight. More preferred.

The solvent used in the above reaction is preferably N-methyl-2-pyrrolidone or γ-butyrolactone from the viewpoint of solubility of the monomer and the polymer, and these may be used alone or in combination of two or more. .
The polymer concentration at the time of production is preferably 1 to 30% by mass, more preferably 5 to 20% by mass, since precipitation of the polymer hardly occurs and a high molecular weight product is easily obtained.
Further, in order to prevent hydrolysis of the tetracarboxylic acid diester dichloride, the solvent used for producing the polyamic acid ester is preferably dehydrated as much as possible, and it is preferable to prevent outside air from being mixed in a nitrogen atmosphere.

[3] When Produced from Tetracarboxylic Diester and Diamine The polyamic acid ester can be produced by polycondensation of a tetracarboxylic diester and a diamine component containing the diamine of the present invention.
Specifically, a tetracarboxylic acid diester and a diamine are mixed with a condensing agent, a base, and an organic solvent at 0 to 150 ° C, preferably 0 to 100 ° C, for 30 minutes to 24 hours, preferably 3 to 15 hours. It can be produced by reacting for hours.
Examples of the condensing agent include triphenyl phosphite, dicyclohexylcarbodiimide, 1-ethyl-3- (3-dimethylaminopropyl) carbodiimide hydrochloride, N, N′-carbonyldiimidazole, dimethoxy-1,3,5-triazinyl Methylmorpholinium, O- (benzotriazol-1-yl) -N, N, N ', N'-tetramethyluronium tetrafluoroborate, O- (benzotriazol-1-yl) -N, N, N ', N'-tetramethyluronium hexafluorophosphate, diphenyl (2,3-dihydro-2-thioxo-3-benzoxazolyl) phosphonate and the like can be used. The addition amount of the condensing agent is preferably 2 to 3 times mol, more preferably 2 to 2.5 times mol, based on the tetracarboxylic acid diester.

Tertiary amines such as pyridine and triethylamine can be used as the base. The amount of the base to be added is preferably 2 to 4 times, more preferably 2.5 to 3.5 times the mol of the diamine component, from the viewpoint that the base can be easily removed and a high molecular weight substance is easily obtained.
In the above reaction, the reaction proceeds efficiently by adding a Lewis acid as an additive. As the Lewis acid, lithium halides such as lithium chloride and lithium bromide are preferable. The addition amount of the Lewis acid is preferably 0 to 1.0 times, more preferably 0 to 0.7 times, the mol of the diamine component.

Among the above three methods for producing a polyamic acid ester, the method of the above [1] or [2] is particularly preferable because a high molecular weight polyamic acid ester is obtained.
The solution of the polyamic acid ester obtained as described above can be poured into a poor solvent with good stirring to precipitate a polymer. After performing precipitation several times, washing with a poor solvent, and drying at room temperature or by heating, a purified polyamic acid ester powder can be obtained. The poor solvent is not particularly limited, and examples thereof include water, methanol, ethanol, hexane, butyl cellosolve, acetone, and toluene.

5. Method for Producing Polyimide The polyimide used in the present invention can be produced by imidizing the polyimide precursor.
In the polyimide of the present invention, the ring closure ratio (imidization ratio) of the amic acid group or amic acid ester group does not necessarily need to be 100%, and may be arbitrarily adjusted according to the application and purpose.
Examples of the method for ring-closing the polyimide precursor include thermal imidization in which the polyimide precursor is heated without using a catalyst and catalytic imidization in which a catalyst is used.
When the polyimide precursor is thermally imidized, a method of heating the solution of the polyimide precursor to 100 to 400 ° C., preferably 120 to 250 ° C. and removing water or alcohol generated by the imidation reaction out of the system is preferred. Is preferred.

Catalytic imidation of the polyimide precursor can be performed by adding a basic catalyst and an acid anhydride to a polyamic acid solution and stirring the mixture 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, of the amic acid group, and the amount of the acid anhydride is 1 to 50 mol times, preferably 3 to 30 mol of the amic acid group. It is twice.
Examples of the basic catalyst include pyridine, triethylamine, trimethylamine, tributylamine, trioctylamine, and the like. Among them, pyridine is preferable because it has an appropriate basicity for causing the reaction to proceed.
Examples of the acid anhydride include acetic anhydride, trimellitic anhydride, and pyromellitic anhydride. Among them, acetic anhydride is preferred because purification after the reaction is easy. The imidization rate by the catalytic imidization can be controlled by adjusting the amount of the catalyst, the reaction temperature, and the reaction time.

  When recovering the polymer component from the polyimide reaction solution, the reaction solution may be poured into a poor solvent to cause precipitation. Examples of the poor solvent used for the precipitation include methanol, acetone, hexane, butyl cellosolve, heptane, methyl ethyl ketone, methyl isobutyl ketone, ethanol, toluene, benzene, water and the like. It is preferable that the polymer put into the poor solvent and precipitated is collected by filtration and then dried at normal temperature or reduced pressure at normal temperature or under heating.

6. Liquid crystal aligning agent A liquid crystal aligning agent is a coating solution for producing a liquid crystal aligning film, and its main component is a composition containing a resin component for forming a resin film and an organic solvent for dissolving the resin component. Things. In the liquid crystal aligning agent of the present invention, as the resin component, at least one polymer selected from the group consisting of the above-mentioned polyimide precursor and a polyimide obtained by ring-closing the polyimide precursor is used.

The concentration of the polymer in the liquid crystal aligning agent can be appropriately changed by setting the thickness of the coating film to be formed. The amount is preferably 1% by mass or more from the viewpoint of forming a uniform and defect-free coating film, and is preferably 10% by mass or less from the viewpoint of storage stability of the solution. A particularly preferred concentration of the polymer is 2 to 8% by mass.
All of the resin components in the liquid crystal alignment agent may be the polymer of the present invention, or a polymer other than the polymer of the present invention may be mixed. Examples of such another polymer include a polyimide precursor or polyimide obtained by using a diamine other than the formula (1) as the diamine component.

  The organic solvent contained in the liquid crystal aligning agent is not particularly limited as long as the polymer component is uniformly dissolved. Specific examples thereof include N, N-dimethylformamide, N, N-diethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-methylcaprolactam, Examples thereof include 2-pyrrolidone, N-vinyl-2-pyrrolidone, dimethyl sulfoxide, dimethyl sulfone, γ-butyrolactone, 1,3-dimethyl-imidazolidinone, and 3-methoxy-N, N-dimethylpropanamide. These may be used alone or in combination of two or more. In addition, even if the solvent alone cannot dissolve the polymer component uniformly, it may be mixed with the above organic solvent as long as the polymer is not precipitated.

The liquid crystal aligning agent may contain a solvent for improving the uniformity of the coating when the liquid crystal aligning agent is applied to the substrate, in addition to the organic solvent for dissolving the polymer component. As such a solvent, generally, a solvent having a lower surface tension than the above organic solvent is used. Specific examples thereof include ethyl cellosolve, butyl cellosolve, ethyl carbitol, butyl carbitol, ethyl carbitol acetate, ethylene glycol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, and 1-butoxy-2-propanol. , 1-phenoxy-2-propanol, propylene glycol monoacetate, propylene glycol diacetate, propylene glycol-1-monomethyl ether-2-acetate, propylene glycol-1-monoethyl ether-2-acetate, butyl cellosolve acetate, dipropylene glycol , 2- (2-ethoxypropoxy) propanol, methyl lactate, ethyl lactate, n-propyl lactate, n-butyl lactate, isobutyl lactate Glycol ester and the like. Two or more of these solvents may be used in combination.
The solvent is a poor solvent having low solubility of the resin. The amount of these solvents is preferably 5 to 60% by mass, more preferably 10 to 50% by mass of the organic solvent contained in the liquid crystal alignment treatment agent.

In addition to the above, the liquid crystal aligning agent may be a polymer other than the polymer of the present invention, as long as the effects of the present invention are not impaired. A dielectric or conductive material, a silane coupling agent for the purpose of improving the adhesion between the liquid crystal alignment film and the substrate, a crosslinkable compound for the purpose of increasing the hardness and denseness of the film when the liquid crystal alignment film, and further, When firing the coating film, an imidization accelerator or the like for the purpose of efficiently promoting the imidization of the polyimide precursor may be added.
When a crosslinkable compound such as a functional silane-containing compound or an epoxy group-containing compound is contained, the amount thereof is preferably 0.1 to 30 parts by mass, more preferably 100 parts by mass, more preferably 100 parts by mass of the resin component. The amount is 1 to 20 parts by mass, particularly preferably 1 to 10 parts by mass.

7. Method for Manufacturing Liquid Crystal Alignment Film The liquid crystal alignment film is a film obtained by applying the above liquid crystal alignment agent to a substrate, drying and firing.
The substrate on which the liquid crystal alignment agent is applied is not particularly limited as long as it is a substrate having high transparency, and a glass substrate, a silicon nitride substrate, an acrylic substrate, a plastic substrate such as a polycarbonate substrate, or the like can be used. In particular, 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 simplifying the process.
In a reflection type liquid crystal display device, an opaque material such as a silicon wafer can be used as long as only one substrate is used. In this case, a material which reflects light such as aluminum can be used.

Examples of the method for applying the liquid crystal aligning agent include a spin coating method, a printing method, an ink jet method, and the like. Other methods using a coating liquid include a dip, a roll coater, a slit coater, and a spinner, and these may be used according to the purpose.
In the drying and baking steps after the application of the liquid crystal aligning agent, any temperature and time can be selected. Usually, in order to sufficiently remove the contained organic solvent, drying at 50 to 120 ° C., preferably 50 to 80 ° C., for 1 to 10 minutes, preferably 3 to 5 minutes, and then 150 to 300 ° C. The firing is preferably performed at 200 to 240 ° C. for 5 to 120 minutes, preferably 10 to 40 minutes.
The thickness of the coating film after baking is not particularly limited, but if it is too thin, the reliability of the liquid crystal display element may be reduced. Therefore, the thickness is 5 to 300 nm, preferably 10 to 200 nm.

  Examples of a method for subjecting the obtained liquid crystal alignment film to an alignment treatment include a rubbing method and a photo-alignment treatment method. Rayon cloth, nylon cloth, cotton cloth, or the like can be used for the rubbing treatment. Since it is difficult to obtain a uniform alignment state by a rubbing treatment, the liquid crystal alignment film for vertical alignment can be used without rubbing when used as a liquid crystal alignment agent for vertical alignment.

As a specific example of the photo-alignment treatment method, a method of irradiating the coating film surface with radiation deflected in a fixed direction and, in some cases, performing a heat treatment at a temperature of 150 to 250 ° C. to impart liquid crystal alignment capability Is mentioned. As the radiation, ultraviolet light and visible light having a wavelength of 100 to 800 nm can be used. Among them, ultraviolet rays having a wavelength of 100 to 400 nm are preferable, and ultraviolet rays having a wavelength of 200 to 400 nm are particularly preferable.
Further, in order to improve the liquid crystal alignment, the coated substrate may be irradiated with radiation while being heated at 50 to 250 ° C.
The dose of radiation is preferably ^{1~10,000mJ / cm 2, 100~5,000mJ / cm} 2 is particularly preferred. The liquid crystal alignment film manufactured as described above can stably align liquid crystal molecules in a certain direction.

The film irradiated with the polarized radiation described above may then be subjected to contact treatment with a solvent containing at least one selected from water and an organic solvent.
The solvent used for the contact treatment is not particularly limited as long as the solvent dissolves the decomposed product generated by light irradiation. Specific examples include water, methanol, ethanol, 2-propanol, acetone, methyl ethyl ketone, 1-methoxy-2-propanol, 1-methoxy-2-propanol acetate, butyl cellosolve, ethyl lactate, methyl lactate, diacetone alcohol, and 3-acetone alcohol. Examples include methyl methoxypropionate, ethyl 3-ethoxypropionate, propyl acetate, butyl acetate, and cyclohexyl acetate. Two or more of these solvents may be used in combination.
From the viewpoint of versatility and safety, at least one selected from the group consisting of water, 2-propanol, 1-methoxy-2-propanol, and ethyl lactate is more preferable. 1-methoxy-2-propanol or ethyl lactate is particularly preferred.

In the present invention, the contact treatment between the film irradiated with the polarized radiation and the solution containing the organic solvent is performed by a treatment such as immersion treatment or spraying treatment that makes sufficient contact between the film and the liquid. Is preferred. Among them, a method of immersing the film in a solution containing an organic solvent is preferably for 10 seconds to 1 hour, more preferably for 1 to 30 minutes. The contact treatment may be carried out at normal temperature or at elevated temperature, but is preferably carried out at 10 to 80C, more preferably at 20 to 50C. Further, if necessary, a means for enhancing contact with ultrasonic waves or the like can be provided.
After the above-mentioned contact treatment, for the purpose of removing the organic solvent in the solution used, any of a rinse or drying with a low boiling point solvent such as water, methanol, ethanol, 2-propanol, acetone, and methyl ethyl ketone; or You can do both.

Further, the film subjected to the contact treatment with the solvent may be heated at 150 ° C. or higher for the purpose of drying the solvent and reorienting the molecular chains in the film.
The heating temperature is preferably from 150 to 300C. The higher the temperature, the more the reorientation of the molecular chain is promoted. However, if the temperature is too high, the molecular chain may be decomposed. Therefore, the heating temperature is more preferably 180 to 250 ° C, and particularly preferably 200 to 230 ° C.
If the heating time is too short, the effects of the present invention may not be obtained. If the heating time is too long, the molecular chain may be decomposed. Thus, the heating time is preferably 10 seconds to 30 minutes, and more preferably 1 to 10 minutes. More preferred.

8. Liquid crystal display device After obtaining a substrate with a liquid crystal alignment film obtained from the liquid crystal alignment agent of the present invention, a liquid crystal cell was manufactured by a known method, and the liquid crystal cell was used as a liquid crystal display device. Things.
As an example of a method for manufacturing a liquid crystal cell, a liquid crystal display element having a passive matrix structure will be described as an example. Note that a liquid crystal display element having an active matrix structure in which a switching element such as a TFT (Thin Film Transistor) is provided in each pixel portion forming an image display may be used.

First, a transparent glass substrate is prepared, and a common electrode is provided on one substrate, and a segment electrode is provided on the other substrate. These electrodes can be, for example, ITO electrodes, and are patterned so as to display a desired image. Next, an insulating film is provided on each substrate so as to cover the common electrode and the segment electrodes. The insulating film can be, for example, a film made of SiO ₂ —TiO ₂ formed by a sol-gel method.
Next, the liquid crystal alignment film of the present invention is formed on each substrate. Next, the other substrate is superimposed on one substrate so that the alignment film surfaces thereof face each other, and the periphery thereof is bonded with a sealant. Normally, a spacer is mixed in the sealing material in order to control the gap between the substrates. In addition, it is preferable that spacers for controlling the gap between the substrates are sprayed on the in-plane portion where the sealing material is not provided. Part of the sealing material is provided with an opening through which liquid crystal can be filled from the outside.

Next, a liquid crystal material is injected into a space surrounded by the two substrates and the sealant through an opening provided in the sealant. Thereafter, the opening is sealed with an adhesive. For the injection, a vacuum injection method may be used, or a method utilizing a capillary phenomenon in the atmosphere may be used. Alternatively, the liquid crystal can be filled by dropping a liquid crystal after drawing a sealant on the substrate and bonding the liquid crystal under reduced pressure.
Either a positive liquid crystal material or a negative liquid crystal material may be used as the liquid crystal material. In particular, even when a negative-type liquid crystal material having a lower voltage holding ratio than that of the positive-type liquid crystal material is used, the use of the liquid crystal alignment film of the present invention provides excellent afterimage characteristics.

  Next, a polarizing plate is installed. Specifically, a pair of polarizing plates is attached to surfaces of the two substrates opposite to the liquid crystal layer. Through the above steps, the liquid crystal display device of the present invention is obtained. Since this liquid crystal display element uses a liquid crystal alignment film obtained by the method for producing a liquid crystal alignment film of the present invention as a liquid crystal alignment film, it has excellent afterimage characteristics and is a high-definition multifunctional mobile phone. (Smartphones), tablet computers, liquid crystal televisions, etc.

  Hereinafter, the present invention will be specifically described with reference to examples and the like, but the present invention is not limited to these examples. The abbreviations of the compound and the solvent are as follows.

Ｂｏｃ：tert-ブトキシカルボニル基
ＢＣＳ： ブチルセロソルブ

Boc: tert-butoxycarbonyl group BCS: butyl cellosolve

窒素雰囲気下、４口フラスコにジメチルホルムアミド（３９０ｇ）、４−フルオロニトロベンゼン（６５．０ｇ、０．４６１ｍｏｌ）、４―アミノメチルピペリジン（２５．０ｇ、０．２１９ｍｏｌ）、及び炭酸カリウム(９０．９ｇ、０．６５８ｍｏｌ)を加え、６０℃で反応させた。２２時間加熱攪拌後、中間体の消失をＨＰＬＣで確認した。その後、ろ過により炭酸カリウムを除去し、さらに、炭酸カリウムをジメチルホルムアミド２５０ｇで２回洗浄した。得られた溶液を、内容物が２９５ｇになるまで減圧留去し、その後、水１.５０ｋｇを加えて、化合物（１１）を析出させた。その後、析出物をろ過により回収し、乾燥して、化合物（１１）の粗物を得た。得られた粗物を、テトラヒドロフランにて再結晶して精製し、黄色固体の化合物（１１）を得た（５８．８ｇ、０．１６５ｍｏｌ、収率７５．３％）。
ＨＰＬＣ測定；島津製作所社製 Prominence Series、
ＮＭＲ測定；
装置：Ｖａｒｉａｎ ＮＭＲ Ｓｙｓｔｅｍ ４００ ＮＢ （４００ ＭＨｚ）
基準物質：テトラメチルシラン（ＴＭＳ）（δ＝０．０ ｐｐｍ）(Example 1)
Synthesis of (DA-1)

Under a nitrogen atmosphere, dimethylformamide (390 g), 4-fluoronitrobenzene (65.0 g, 0.461 mol), 4-aminomethylpiperidine (25.0 g, 0.219 mol), and potassium carbonate (90.9 g) were placed in a four-necked flask. , 0.658 mol) and reacted at 60 ° C. After heating and stirring for 22 hours, disappearance of the intermediate was confirmed by HPLC. Thereafter, potassium carbonate was removed by filtration, and the potassium carbonate was further washed twice with 250 g of dimethylformamide. The obtained solution was distilled off under reduced pressure until the content became 295 g, and then 1.50 kg of water was added to precipitate the compound (11). Thereafter, the precipitate was collected by filtration and dried to obtain a crude compound (11). The obtained crude product was purified by recrystallization from tetrahydrofuran to obtain compound (11) as a yellow solid (58.8 g, 0.165 mol, yield 75.3%).
HPLC measurement; Prominence Series manufactured by Shimadzu Corporation,
NMR measurement;
Apparatus: Varian NMR System 400 NB (400 MHz)
Reference substance: tetramethylsilane (TMS) (δ = 0.0 ppm)

The structure of compound (11) was confirmed by obtaining the following spectral data by ¹ H-NMR analysis.
The structure of the compound obtained in the subsequent synthesis was confirmed by ¹ H-NMR analysis, similarly to the compound (11).
¹ H-NMR (DMSO):
δ = 8.05-7.98 (m, 4H), 7.41 (t, 1H J = 6.8), 7.02 (d, 2H, J = 9.6), 6.68 (d, 2H, J = 9.2), 4.09 (d, 2H, J = 13.6), 3.10 (t, 2H, J = 6.0), 2.98 (t, 2H, J = 12) 1.0), 1.91-1.89 (m, 1H), 1.89-1.83 (m, 2H), 1.29-1.19 (m, 2H).

窒素雰囲気下、４口フラスコにテトラヒドロフラン（４００ｇ）、化合物（１１）（２０．０ｇ、０．０５６１ｍｏｌ）、及びＮ、Ｎ―ジメチル−４−アミノピリジン（７７．４ｍｇ、０．６３４ｍｍｏｌ）を加え、５０℃に加熱した。その溶液へ、二炭酸ジ-tert−ブチル(１５．３ｇ、０．０６９９ｍｏｌ)とテトラヒドロフラン１５.０ｇの混合液を滴下し、２４時間反応させた。その後、ＨＰＬＣにて原料が消失したことを確認した。次いで、内容物を減圧留去した後、トルエンによって再結晶を行った。析出した結晶をろ取し、乾燥させて、黄色固体の化合物（１２）を収率８７．３％で得た（２２．３ｇ、０．０４８９ｍｏｌ）。

Under a nitrogen atmosphere, tetrahydrofuran (400 g), compound (11) (20.0 g, 0.0561 mol), and N, N-dimethyl-4-aminopyridine (77.4 mg, 0.634 mmol) were added to a four-necked flask, Heated to 50 ° C. A mixture of di-tert-butyl dicarbonate (15.3 g, 0.0699 mol) and 15.0 g of tetrahydrofuran was added dropwise to the solution and reacted for 24 hours. Thereafter, it was confirmed by HPLC that the raw materials had disappeared. Next, after the content was distilled off under reduced pressure, recrystallization was performed with toluene. The precipitated crystals were collected by filtration and dried to obtain a yellow solid compound (12) at a yield of 87.3% (22.3 g, 0.0489 mol).

¹ H-NMR (DMSO): δ = 8.21 (d, 2H, J = 8.8), 8.01 (d, 2H J = 9.2), 7.61 (d, 2H, J = 9) .2), 6.98 (d, 2H, J = 9.6), 4.02 (d, 2H, J = 13.6), 3.69 (d, 2H, J = 7.2), 2 .91 (t, 2H, J = 11.6), 1.86-1.70 (m, 1H), 1.66 (d, 2H, J = 11.2), 1.42 (s, 9H) , 1.22-1.10 (m, 2H).

窒素雰囲気下、４口フラスコにテトラヒドロフラン（４４７ｇ）、化合物（１２）（２２．３ｇ、０．０４８９ｍｏｌ）、及びパラジウムカーボン粉末（１．１６ｇ）を加えた後、フラスコ内を水素雰囲気に置換し、室温で２３時間攪拌した。その後、ＨＰＬＣにて、原料が消失したことを確認した。その後、パラジウムカーボンをろ過し、得られた溶液を減圧留去して粗物を得た。得られた粗物にクロロホルム（２０６ｇ）を加え、６０℃に加温した。その後、６０℃の水（１００ｇ）で２回、分液操作を繰り返した。得られた有機層に、活性炭（０．７５４ｇ）を加えて攪拌した後、ろ過により活性炭を除去した。内容物を濃縮し、トルエンで再結晶を行った。その後、乾燥して、薄クリーム色固体の目的物（ＤＡ−１）を、収率７１．３％で得た（１３．８ｇ、０．０３４９ｍｏｌ）。

Under a nitrogen atmosphere, tetrahydrofuran (447 g), compound (12) (22.3 g, 0.0489 mol), and palladium carbon powder (1.16 g) were added to a four-necked flask, and the atmosphere in the flask was replaced with a hydrogen atmosphere. Stirred at room temperature for 23 hours. Thereafter, it was confirmed by HPLC that the raw materials had disappeared. Thereafter, palladium carbon was filtered, and the obtained solution was distilled off under reduced pressure to obtain a crude product. Chloroform (206 g) was added to the obtained crude product, and the mixture was heated to 60 ° C. Thereafter, the liquid separation operation was repeated twice with water (100 g) at 60 ° C. Activated carbon (0.754 g) was added to the obtained organic layer and stirred, and then the activated carbon was removed by filtration. The contents were concentrated and recrystallized from toluene. Thereafter, drying was performed to obtain the target product (DA-1) as a light cream solid in a yield of 71.3% (13.8 g, 0.0349 mol).

¹ H-NMR (DMSO): δ = 6.83 (d, 2H, J = 8.0), 6.65 (d, 2H J = 8.4), 6.50 (d, 2H, J = 8) .4), 6.45 (d, 2H, J = 8.4), 5.05 (br, 2H), 4.54 (br, 2H), 3.41 (d, 2H, J = 6.8). ), 3.29 (d, 2H, J = 12.4), 2.36 (t, 2H, J = 10.8), 1.64 (d, 2H, J = 11.6), 1.42 -1.19 (br, 12H).

窒素雰囲気下、４口フラスコにテトラヒドロフラン（５３４ｇ）、（実施例１）で得た化合物（１１）（２１．４ｇ、０．０６０１ｍｏｌ）、及びカリウム−tert−ブトキシド（８．１０ｇ、０．０７２２ｍｏｌ）を加え、室温で攪拌させた溶液に、ヨウ化メチル（９．３５ｇ、０．０６６０ｍｏｌ）を滴下し、４０℃に昇温した。２４時間反応させた後、さらに、ヨウ化メチル（１０．２ｇ、０．０７１７ｍｏｌ）、及びカリウム−tert−ブトキシド（２．９８ｇ、０．０２６６ｍｏｌ）を加え、ＨＰＬＣにて原料が消失したことを確認した。その後、水１００ｇを加えて反応を停止させた。反応液を減圧留去して得られた粗物に、水５００ｇを加えて、スラリー状態で２４時間攪拌を行い、固体をろ過し、乾燥した。その後、テトラヒドロフランで再結晶を行い、黄色固体の化合物（１３）を収率７８．２％で得た（１７．４ｇ、０．０４７０ｍｏｌ）。(Example 2)
Synthesis of (DA-2)

Under a nitrogen atmosphere, tetrahydrofuran (534 g), the compound (11) obtained in Example 1 (21.4 g, 0.0601 mol), and potassium tert-butoxide (8.10 g, 0.0722 mol) were placed in a four-necked flask. Was added, and methyl iodide (9.35 g, 0.0660 mol) was added dropwise to the solution stirred at room temperature, and the temperature was raised to 40 ° C. After reacting for 24 hours, methyl iodide (10.2 g, 0.0717 mol) and potassium-tert-butoxide (2.98 g, 0.0266 mol) were further added, and it was confirmed by HPLC that the raw materials had disappeared. did. Thereafter, 100 g of water was added to stop the reaction. 500 g of water was added to the crude product obtained by evaporating the reaction solution under reduced pressure, the mixture was stirred in a slurry state for 24 hours, and the solid was filtered and dried. Thereafter, recrystallization was performed with tetrahydrofuran to obtain compound (13) as a yellow solid in a yield of 78.2% (17.4 g, 0.0470 mol).

¹ H-NMR (DMSO): δ = 8.03 (d, 4H, J = 9.2), 7.01 (d, 2H J = 9.6), 6.82 (d, 2H, J = 9) .2), 4.10 (d, 2H, J = 13.6), 3.42 (d, 2H, J = 7.2), 3.09 (s, 3H), 2.95 (t, 2H) , J = 12.0), 2.15-2.10 (m, 1H), 1.68 (d, 2H, J = 11.2), 1.33-1.23 (m, 2H).

窒素雰囲気下、４口フラスコにテトラヒドロフラン（６９７ｇ）、化合物（１３）（１７．４ｇ、０．０４７０ｍｏｌ）、及びパラジウムカーボン粉末（０．９３０ｇ）を加えた後、フラスコ内を水素雰囲気に置換し、６０℃で４０時間攪拌した。その後、ＨＰＬＣにて、原料が消失したことを確認した。その後、パラジウムカーボンをろ過して得られた溶液を、減圧留去して粗物を得た。得られた粗物に酢酸エチル４５０ｇを加え、４５０ｇの水で２回、分液操作を繰り返した。得られた有機層に、活性炭（０．７３９ｇ）を加えて攪拌した後、ろ過により活性炭を除去した。得られた濾液を濃縮し、粗物をトルエンで再結晶した。次いで、結晶を乾燥して、薄紫色固体の目的物、（ＤＡ−２）を収率７１．６％で得た（１０．５ｇ、０．０３３７ｍｏｌ）。

Under a nitrogen atmosphere, tetrahydrofuran (697 g), compound (13) (17.4 g, 0.0470 mol), and palladium carbon powder (0.930 g) were added to a four-necked flask, and the atmosphere in the flask was replaced with a hydrogen atmosphere. Stirred at 60 ° C. for 40 hours. Thereafter, it was confirmed by HPLC that the raw materials had disappeared. Thereafter, the solution obtained by filtering palladium carbon was distilled off under reduced pressure to obtain a crude product. 450 g of ethyl acetate was added to the obtained crude product, and the liquid separation operation was repeated twice with 450 g of water. Activated carbon (0.739 g) was added to the obtained organic layer and stirred, and then the activated carbon was removed by filtration. The obtained filtrate was concentrated, and the crude product was recrystallized from toluene. Next, the crystals were dried to obtain the target substance (DA-2) as a light purple solid in a yield of 71.6% (10.5 g, 0.0337 mol).

¹ H-NMR (DMSO): δ = 6.67 (d, 2H, J = 9.2), 6.54-6.45 (m, 6H), 4.54 (br, 2H), 4.36 (Br, 2H), 3.32 (m, 2H), 2.98 (d, 2H, J = 6.8), 2.75 (s, 3H), 2.40 (t, 2H, J = 10) 1.0), 1.70-1.60 (br, 3H), 1.31-1.23 (m, 2H).

窒素雰囲気下、４口フラスコにジメチルホルムアミド（１４４ｇ）、炭酸カリウム（６５．６ｇ、０．４７５ｍｏｌ）、４−フルオロニトロベンゼン（３３．５g、０．２３７ｍｏｌ）、及び４−ヒドロキシピペリジン（２４．０ｇ、０．２３７ｍｏｌ）を仕込み、８０℃にて１６時間攪拌した。その後、無機塩を減圧ろ過により除去し、ろ液を酢酸エチル（２８８ｇ）で希釈した。次いで、有機相を純水（２８８ｇ）で３回洗浄し、硫酸ナトリウムで脱水処理した。その後、濃縮し乾燥して、化合物（１４）４５．５ｇ（０．２０５ｍｏｌ、収率８６．３％、黄色固体）を得た。(Comparative Example 1)
Synthesis of (DA-4)

Under a nitrogen atmosphere, dimethylformamide (144 g), potassium carbonate (65.6 g, 0.475 mol), 4-fluoronitrobenzene (33.5 g, 0.237 mol), and 4-hydroxypiperidine (24.0 g, 0.237 mol) and stirred at 80 ° C. for 16 hours. Thereafter, the inorganic salts were removed by filtration under reduced pressure, and the filtrate was diluted with ethyl acetate (288 g). Next, the organic phase was washed three times with pure water (288 g) and dehydrated with sodium sulfate. Thereafter, the mixture was concentrated and dried to obtain 45.5 g (0.205 mol, yield: 86.3%, yellow solid) of compound (14).

¹ H-NMR (DMSO): δ = 8.02 (d, 2H J = 9.6), 7.00 (d, 2H J = 9.6), 4.79 (d, 1H, J = 4. 0), 3.90-3.72 (m, 3H), 3.26-3.19 (m, 2H), 1.86-1.76 (m, 2H), 1.47-1.35 ( m, 2H).

窒素雰囲気下、４口フラスコに水素化ナトリウム（６０質量％、流動パラフィン分散品）（３．２４ｇ、０．０８１０ｍｏｌ）を仕込み、テトラヒドロフラン（３０.０ｇ）を加えた。その後、氷冷攪拌しながら、化合物[６]（１５．０ｇ、０．０６７５ｍｏｌ）をテトラヒドロフラン（１２０ｇ）に溶解させた溶液を、１０分間掛けて滴下した。次いで、４−フルオロニトロベンゼン（１０．０ｇ、０．０７０９ｍｏｌ）をテトラヒドロフラン（３０.０ｇ）に溶解させた溶液を滴下した後、室温にて５時間攪拌した。その後、酢酸エチル（３００ｇ）及び純水（３００ｇ）を加え、析出した結晶を、室温にてスラリー洗浄し、結晶を減圧ろ過した。続いて、得られた結晶を取り出し、更に、酢酸エチル（３００ｇ）、及び純水（３００ｇ）を加え、室温にてスラリー洗浄した。その後、この結晶をろ過し、乾燥して、化合物（１５）２０．０ｇ（０．０５８３ｍｏｌ、収率８６．４％、黄色固体）を得た。

Under a nitrogen atmosphere, sodium hydride (60% by mass, liquid paraffin dispersion) (3.24 g, 0.0810 mol) was charged into a four-necked flask, and tetrahydrofuran (30.0 g) was added. Thereafter, a solution of compound [6] (15.0 g, 0.0675 mol) dissolved in tetrahydrofuran (120 g) was added dropwise over 10 minutes while stirring with ice cooling. Next, a solution in which 4-fluoronitrobenzene (10.0 g, 0.0709 mol) was dissolved in tetrahydrofuran (30.0 g) was added dropwise, and the mixture was stirred at room temperature for 5 hours. Thereafter, ethyl acetate (300 g) and pure water (300 g) were added, and the precipitated crystals were slurry-washed at room temperature and filtered under reduced pressure. Subsequently, the obtained crystals were taken out, and further, ethyl acetate (300 g) and pure water (300 g) were added, and the resultant was subjected to slurry washing at room temperature. Thereafter, the crystals were filtered and dried to obtain 20.0 g (0.0583 mol, yield 86.4%, yellow solid) of compound (15).

¹ H-NMR (DMSO): δ = 8.19 (d, 2H, J = 9.6), 8.05 (d, 2H J = 9.6), 7.22 (d, 2H, J = 9). .6), 7.06 (d, 2H, J = 9.6), 4.96-4.86 (m, 1H), 3.89-3.80 (m, 2H), 3.48-3 .40 (m, 2H), 2.12 to 2.05 (m, 2H), 1.77-1.67 (m, 2H).

窒素雰囲気下、オートクレーブにテトラヒドロフラン（３００ｇ）、化合物（１５）（２０．０１ｇ、０．０５８３ｍｏｌ）、及びパラジウムカーボン粉末（４．００ｇ）を仕込んだ。その後、容器内を水素０．８ＭＰａに置換し、５０℃にて４時間攪拌した。次いで、パラジウムカーボンをろ過し、ろ液を濃縮し、乾燥した。その後、析出した結晶を、メタノール（１２０ｇ）で懸濁させた。懸濁液を６０℃にて１時間攪拌し、溶解させた後、更に氷浴下３０分間攪拌した。析出した結晶をろ過し、メタノール１０.０ｇで洗浄し、乾燥して、目的物（ＤＡ−４）８．８０ｇ（０．０３１１ｍｏｌ、収率５３．３％、紫色結晶）を得た。

Under a nitrogen atmosphere, an autoclave was charged with tetrahydrofuran (300 g), compound (15) (20.01 g, 0.0583 mol), and palladium carbon powder (4.00 g). Thereafter, the inside of the vessel was replaced with hydrogen 0.8 MPa, and the mixture was stirred at 50 ° C. for 4 hours. Then, the palladium carbon was filtered, and the filtrate was concentrated and dried. Thereafter, the precipitated crystals were suspended in methanol (120 g). The suspension was stirred at 60 ° C. for 1 hour to dissolve, and then further stirred in an ice bath for 30 minutes. The precipitated crystals were collected by filtration, washed with 10.0 g of methanol, and dried to obtain 8.80 g (0.0311 mol, yield 53.3%, purple crystals) of the target product (DA-4).

¹ H-NMR (DMSO): δ = 6.72-6.64 (m, 4H), 6.52-6.44 (m, 4H), 4.63 (br, 2H), 4.56 (br) , 2H), 4.19-4.10 (m, 1H), 3.24-3.15 (m, 2H), 2.77-2.68 (m, 2H), 2.00-1.91. (M, 2H), 1.71-1.60 (m, 2H).

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

(Example 3)
1.98 g (5.00 mmol) of DA-1 was weighed and placed in a 50 mL four-necked flask equipped with a stirrer and a nitrogen inlet tube, and 20.8 g of NMP was added thereto. While stirring this diamine solution, 1.03 g (4.75 mmol) of acid dianhydride (A) was added, and 5.20 g of NMP was further added. The mixture was stirred at 23 ° C. for 3 hours under a nitrogen atmosphere to obtain a polyamic acid. A solution (PAA-1) was obtained. The viscosity of this polyamic acid solution at a temperature of 25 ° C. was 134 mPa · s.

  7.92 g of the polyamic acid solution (PAA-1) obtained in Synthesis Example 2 was placed in a 100 mL Erlenmeyer flask containing a stirrer, 2.56 g of NMP, and 1 part of 3-glycidoxypropyltriethoxysilane. 0.67 g of an NMP solution containing mass% and 3.72 g of BCS were added, and the mixture was stirred with a magnetic stirrer for 2 hours to obtain a liquid crystal aligning agent (A-1).

(Example 4)
2.17 g (7.00 mmol) of DA-2 was weighed and placed in a 50 mL four-necked flask equipped with a stirrer and a nitrogen inlet tube, 24.7 g of NMP was added, and the mixture was stirred and dissolved while sending nitrogen. While stirring the diamine solution, 1.26 g (5.77 mmol) of acid dianhydride (A) was added, and 6.19 g of NMP was further added. The mixture was stirred at 23 ° C. for 3 hours under a nitrogen atmosphere to obtain a polyamic acid. A solution (PAA-2) was obtained. The viscosity at a temperature of 25 ° C. of this polyamic acid solution was 150 mPa · s.

  In a 100 mL Erlenmeyer flask containing a stirrer, 8.84 g of the polyamic acid solution (PAA-2) obtained in Synthesis Example 1 was taken, 4.09 g of NMP, and 1 of 3-glycidoxypropyltriethoxysilane were added. 0.82 g of an NMP solution containing mass% and 4.59 g of BCS were added, and the mixture was stirred with a magnetic stirrer for 2 hours to obtain a liquid crystal aligning agent (A-2).

(Comparative Example 2)
In a 100 mL four-necked flask equipped with a stirrer and a nitrogen inlet tube, 5.16 g (20.0 mmol) of DA-3 was weighed, 52.2 g of NMP was added, and the mixture was stirred and dissolved while sending nitrogen. While stirring this diamine solution, 4.17 g (19.1 mmol) of acid dianhydride (A) was added, and 31.8 g of NMP was further added. The mixture was stirred at 23 ° C. for 3 hours under a nitrogen atmosphere to obtain a polyamic acid. A solution (PAA-3) was obtained. The viscosity of this polyamic acid solution at a temperature of 25 ° C. was 140 mPa · s.

  In a 100 mL Erlenmeyer flask containing a stirrer, 15.2 g of the polyamic acid solution (PAA-3) obtained in Comparative Synthesis Example 2 was taken, and 7.18 g of NMP and 3-glycidoxypropyltriethoxysilane were added. 1.43 g of an NMP solution containing 1% by mass and 7.94 g of BCS were added, and the mixture was stirred with a magnetic stirrer for 2 hours to obtain a liquid crystal aligning agent (B-1).

(Comparative Example 3)
1.42 g (5.00 mmol) of DA-4 was weighed and placed in a 100 mL four-necked flask equipped with a stirrer and a nitrogen inlet tube, and 16.7 g of NMP was added thereto. While stirring the diamine solution, 0.948 g (4.30 mmol) of acid dianhydride (A) was added, and 4.18 g of NMP was further added. The mixture was stirred at 23 ° C. for 3 hours under a nitrogen atmosphere to obtain a polyamic acid. A solution (PAA-4) was obtained. The viscosity of this polyamic acid solution at a temperature of 25 ° C. was 110 mPa · s.

  In a 100 mL Erlenmeyer flask containing a stirrer, 10.4 g of the polyamic acid solution (PAA-4) obtained in Comparative Synthesis Example 3 was taken, and 3.36 g of NMP and 3-glycidoxypropyltriethoxysilane were added. 0.878 g of an NMP solution containing 1% by weight and 4.88 g of BCS were added, and the mixture was stirred with a magnetic stirrer for 2 hours to obtain a liquid crystal aligning agent (B-2).

Hereinafter, a method for manufacturing a liquid crystal cell I for evaluating the relaxation characteristic of the accumulated charge and a liquid crystal cell II for evaluating the voltage holding ratio and the twist angle will be described.
[Preparation of Liquid Crystal Cell I]
A liquid crystal cell having a configuration of an FFS type liquid crystal display element is manufactured. First, a substrate with electrodes was prepared. The substrate is a glass substrate having a size of 30 mm × 35 mm and a thickness of 0.7 mm. On the substrate, an IZO electrode constituting a counter electrode as a first layer is formed on the entire surface. On the counter electrode of the first layer, a SiN (silicon nitride) film formed by a CVD method is formed as a second layer. The thickness of the second-layer SiN film is 500 nm, and functions as an interlayer insulating film. A comb-shaped pixel electrode formed by patterning an IZO film is arranged as a third layer on the second-layer SiN film, and two pixels of a first pixel and a second pixel are formed. are doing. 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 third-layer pixel electrode has a comb-like shape formed by arranging a plurality of U-shaped electrode elements with a bent central portion. The width in the lateral direction of each electrode element is 3 μm, and the interval between the electrode elements is 6 μm. Since the pixel electrode forming each pixel is formed by arranging a plurality of electrode elements in the shape of a square with a bent central portion, the shape of each pixel is not rectangular, but is similar to the electrode element. It has a shape that resembles a bold character and a U-shape that is bent at Each pixel is vertically divided by a center bent portion, and has a first region above the bent portion and a second region below the bent portion.
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, in the first region of the pixel, the electrode element of the pixel electrode is formed so as to form an angle of + 10 ° (clockwise), and in the second region of the pixel. The electrode elements of the pixel electrodes are formed so as to form an angle of -10 ° (clockwise). That is, 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 application of the voltage between the pixel electrode and the counter electrode in the substrate plane is as follows. They are configured to be in opposite directions.

  Next, the liquid crystal aligning agent was filtered through a 1.0 μm filter, and then applied to the prepared substrate with electrodes by spin coating. After drying on a hot plate at 50 ° C. for 5 minutes, it was baked in a hot air circulating oven at 230 ° C. for 20 minutes to obtain a polyimide film having a thickness of 60 nm. This polyimide film is rubbed with rayon cloth (roller diameter: 120 mm, roller rotation speed: 500 rpm, moving speed: 30 mm / sec, indentation length: 0.3 mm, rubbing direction: inclined by 10 ° with respect to the third-layer IZO comb-teeth electrode. After that, cleaning was performed by irradiating ultrasonic waves in pure water for 1 minute, and water droplets were removed by air blow. Thereafter, the substrate was dried at 80 ° C. for 15 minutes to obtain a substrate with a liquid crystal alignment film. In addition, a polyimide film is formed in the same manner as described above on a glass substrate having a columnar spacer having a height of 4 μm, on the back surface of which an ITO electrode is formed, and an alignment treatment is performed in the same procedure as described above. The obtained substrate with a liquid crystal alignment film was obtained. A pair of these two substrates with a liquid crystal alignment film was formed, and a sealant was printed on the substrate while leaving a liquid crystal injection port, and the other substrate was aligned with the liquid crystal alignment film surfaces facing each other and the rubbing directions were antiparallel. And stuck together. Thereafter, the sealant was cured to produce an empty cell having a cell gap of 4 μm. Liquid crystal ZLI-4792 (manufactured by Merck) was injected into the empty cell by a reduced pressure injection method, and the injection port was sealed to obtain an FFS type liquid crystal cell. Thereafter, the obtained liquid crystal cell was heated at 110 ° C. for 1 hour, left at 23 ° C. overnight, and used for each evaluation.

[Preparation of Liquid Crystal Cell II]
First, a substrate with electrodes was prepared. The substrate is a glass substrate having a size of 30 mm × 40 mm and a thickness of 1.1 mm. An ITO electrode having a thickness of 35 nm is formed on the substrate, and the electrode has a stripe pattern of 40 mm in length and 10 mm in width.
Next, the liquid crystal aligning agent was filtered through a 1.0 μm filter, and then applied to the prepared substrate with electrodes by spin coating. Then, it was dried on a hot plate at 50 ° C. for 5 minutes. Thereafter, baking was performed for 20 minutes in an IR oven at 230 ° C. to form a coating film having a thickness of 100 nm, thereby obtaining a substrate with a liquid crystal alignment film. This liquid crystal alignment film was rubbed with a rayon cloth (roller diameter: 120 mm, roller rotation speed: 1000 rpm, moving speed: 20 mm / sec, indentation length: 0.4 mm), and then subjected to ultrasonic irradiation in pure water for 1 minute. After washing, water droplets were removed by air blow. Thereafter, the substrate was dried at 80 ° C. for 15 minutes to obtain a rubbed substrate with a liquid crystal alignment film. Two substrates with a liquid crystal alignment film were prepared, and a spacer having a diameter of 4 μm (manufactured by Nikki Shokubai Kasei Co., Ltd.) was sprayed on one liquid crystal alignment film surface. Thereafter, a sealant was printed from above, and another substrate was adhered so that the rubbing direction was opposite and the film surfaces faced. Thereafter, the sealing agent was cured to produce an empty cell. Liquid crystal ZLI-4792 (manufactured by Merck) was injected into the empty cell by a reduced pressure injection method, and the injection port was sealed to obtain a liquid crystal cell. Thereafter, the obtained liquid crystal cell was heated at 110 ° C. for 1 hour, left at 23 ° C. overnight, and used for each evaluation.

[Relaxation characteristics of accumulated charge]
The liquid crystal cell I is installed between two polarizing plates arranged so that the polarizing axes are orthogonal to each other. In a state where the pixel electrode and the counter electrode are short-circuited to have the same potential, from under the two polarizing plates, The LED backlight was irradiated, and the angle of the liquid crystal cell was adjusted so that the luminance of the transmitted light of the LED backlight measured on two polarizing plates was minimized.
Next, while applying a rectangular wave having a frequency of 30 Hz to the liquid crystal cell, a VT characteristic (voltage-transmittance characteristic) at a temperature of 23 ° C. was measured, and an AC voltage having a relative transmittance of 23% was obtained. Was calculated. Since this AC voltage corresponds to a region where the change in luminance with respect to the voltage is large, it is convenient to evaluate the accumulated charge through the luminance.

Next, a rectangular wave having a relative transmittance of 23% and a frequency of 30 Hz was applied for 5 minutes, and then a +1.0 V DC voltage was superimposed and driven for 30 minutes. Thereafter, the DC voltage was turned off, and only an AC voltage having a relative transmittance of 23% and a rectangular wave having a frequency of 30 Hz was applied again for 30 minutes.
The faster the relaxation of the accumulated charge, the faster the charge accumulation in the liquid crystal cell when the DC voltage is superimposed. Therefore, the relaxation characteristic of the accumulated charge is that the relative transmittance immediately after the superimposition of the DC voltage is 30% or more. The evaluation was based on the time required for the state to decrease to 23%. The shorter this time is, the better the relaxation characteristics of the accumulated charges are.

[Voltage holding ratio]
A voltage of 1 V was applied to the liquid crystal cell II at a temperature of 85 ° C. for 60 μsec, the voltage after 50 msec was measured, and how much the voltage could be held was evaluated as a voltage holding ratio.

[Twist angle]
The twist angle in the liquid crystal cell II was evaluated using an AxoScan Muller matrix polarimeter manufactured by Optometrics. Originally, if the rubbing direction and the alignment direction of the liquid crystal match, no twist angle occurs in the liquid crystal cell II. The fact that there is a twist angle means that the rubbing direction does not match the alignment direction of the liquid crystal.

[Rubbing resistance]
A liquid crystal aligning agent was spin-coated on the ITO surface of the glass substrate having an ITO electrode on the entire surface, and dried on a hot plate at 50 ° C. for 5 minutes. Thereafter, baking was performed for 20 minutes in an IR oven at 230 ° C. to form a coating film having a thickness of 100 nm, thereby obtaining a substrate with a liquid crystal alignment film. This liquid crystal alignment film was rubbed with a rayon cloth (roller diameter: 120 mm, roller rotation speed: 1000 rpm, moving speed: 20 mm / sec, indentation length: 0.4 mm). This substrate was observed with a microscope, and the film surface was evaluated as “good” when no streaks due to rubbing were observed, and evaluated as “poor” when streaks were observed.

(Example 5)
The liquid crystal aligning agent (A-1) obtained in Example 3 was filtered through a 1.0 μm filter, and then processed as described above, to thereby manufacture a liquid crystal cell I. As a result of evaluating the relaxation property of the stored charge of the liquid crystal cell I, the time required for the relative transmittance to decrease to 23% was 2 minutes, which was favorable.
Next, the liquid crystal aligning agent (A-1) obtained in Example 3 was filtered through a 1.0 μm filter, and then processed as described above, thereby manufacturing a liquid crystal cell II. As a result of evaluating the liquid crystal cell II, the voltage holding ratio was 91% and the twist angle was 0.1 degree.
Next, the liquid crystal aligning agent (A-1) obtained in Example 3 was filtered with a 1.0 μm filter, and the rubbing resistance was evaluated.

(Example 6)
A liquid crystal cell I was produced in the same manner as in Example 5, except that the liquid crystal aligning agent (A-2) obtained in Example 4 was used. With respect to this liquid crystal cell I, as a result of evaluating the relaxation property of the accumulated charge, the time required for the relative transmittance to decrease to 23% was 4 minutes, which was good.
Next, a liquid crystal cell II was produced in the same manner as in Example 5, except that the liquid crystal aligning agent (A-2) obtained in Example 4 was used. As a result of evaluating the liquid crystal cell II, the voltage holding ratio was 92% and the twist angle was 0.1 degree.
Next, the rubbing resistance was evaluated in the same manner as in Example 5, except that the liquid crystal aligning agent (A-2) obtained in Example 4 was used.

(Comparative Example 4)
A liquid crystal cell I was produced in the same manner as in Example 5, except that the liquid crystal aligning agent (B-1) obtained in Comparative Example 2 was used. As a result of evaluating the relaxation property of the accumulated charge, the relative transmittance of the liquid crystal cell I was not reduced to 23% even after elapse of 30 minutes, and the liquid crystal cell I was defective.
Next, a liquid crystal cell II was prepared in the same manner as in Example 5, except that the liquid crystal aligning agent (B-1) obtained in Comparative Example 2 was used. As a result of evaluating the liquid crystal cell II, the voltage holding ratio was 40% and the twist angle was 1.1 degrees.

(Comparative Example 5)
The rubbing resistance was evaluated in the same manner as in Example 5 except that the liquid crystal aligning agent (B-2) obtained in Comparative Example 3 was used.

なお、表１中、「−」は評価していないことを示す。

In Table 1, "-" indicates that evaluation was not performed.

The liquid crystal alignment agent of the present invention is useful as a liquid crystal alignment film used in IPS-driven or FFS-driven liquid crystal display devices, multifunctional mobile phones (smartphones), tablet computers, liquid crystal televisions, and the like.
The entire contents of the specification, claims, and abstract of Japanese Patent Application No. 2014-025438 filed on February 13, 2014 are cited here and incorporated as the disclosure of the specification of the present invention. Things.

Claims (7)

At least one selected from the group consisting of a polyimide precursor obtained by reacting a diamine component containing a diamine represented by the following formula (2) with a tetracarboxylic acid derivative component, and a polyimide obtained by ring-closing the polyimide precursor. A liquid crystal aligning agent comprising one kind of polymer.

(In the formula (2), R ₁ is a hydrogen atom, a methyl group, or a tert-butoxycarbonyl group. R 2 is a hydrogen atom or a methyl group. Q ₁ is a linear alkylene having 1 to 5 carbon atoms. ) The liquid crystal aligning agent according to claim 1, wherein the polyimide precursor is a polymer having a structural unit represented by the following formula (9).

(In the formula (9), X ₁ is a tetravalent organic group derived from a tetracarboxylic acid derivative, Y ₁ is a divalent organic group derived from a diamine represented by the formula (2) , and R ₄ Represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms.) 3. The liquid crystal aligning agent according to claim 2, wherein X1 has the following formula (X-1) to (X-14).

(In the formula (X-1), R _{5 to} R ₈ are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, and 2 to 6 carbon atoms. Is an alkynyl group or a phenyl group.) The liquid crystal aligning agent according to any one of claims 1 to 3, wherein a ratio of the diamine represented by the formula ( 2 ) is 30 to 100 mol% based on 1 mol of all diamine components.   A liquid crystal alignment film obtained from the liquid crystal alignment agent according to claim 1.   The liquid crystal alignment film according to claim 5, wherein the film thickness is 5 to 300 nm.   A liquid crystal display device comprising the liquid crystal alignment film according to claim 5.