WO2020095900A1 - Liquid crystal orientation agent, liquid crystal orientation film, and liquid crystal display element - Google Patents

Abstract

Provided are: a liquid crystal orientation agent for obtaining a liquid crystal orientation film used for photo-alignment methods with which good afterimage characteristics can be obtained even when negative liquid crystal is used without causing bright spots; a liquid crystal orientation film; and a liquid crystal display element. This liquid crystal orientation agent comprises at least one polymer selected from the group consisting of a polyimide precursor that has a structure represented by formula (1) in the main chain and an imidized polymer of the polyimide precursor. (R1 and R2 are a single bond, -O-, -S-, -NR12-, or the like; R12 is a hydrogen atom, or the like; A is an alkylene group having 2 to 20 carbon atoms; and B1 and B2 have the same structure and are a divalent organic group selected from the structures of chemical formula 2.) (R4 is an alkylene group having 1 to 5 carbon atoms; and R5 is a hydrogen atom, or the like.)

Description

Liquid crystal aligning agent, liquid crystal aligning film and liquid crystal display device

The present invention relates to a liquid crystal aligning agent used for manufacturing a liquid crystal display element, a liquid crystal aligning film obtained from the liquid crystal aligning agent, and a liquid crystal display element having the liquid crystal aligning film.

The photo-alignment method is an industrially simple manufacturing process as a rubbingless alignment treatment method. In particular, in a liquid crystal display element of an IPS (In-Plane-Switching) drive system or an FFS (Flinge field Switching) drive system, a rubbing treatment method can be obtained by using the liquid crystal alignment film obtained by the above optical alignment method. The contrast and viewing angle characteristics of the liquid crystal display device can be expected to be improved as compared with the liquid crystal alignment film (Patent Document 1). This makes it possible to improve the performance of the liquid crystal display device, and has been attracting attention as a promising liquid crystal alignment treatment method.

However, the liquid crystal alignment film obtained by the optical alignment method has a problem that the anisotropy with respect to the alignment direction of the polymer film is smaller than that obtained by rubbing. If the anisotropy is small, sufficient liquid crystal alignment cannot be obtained, and when a liquid crystal display device is formed, problems such as the occurrence of an afterimage occur (Non-Patent Document 1).

Japanese Patent Laid-Open No. 9-297313

"Liquid Crystal Photo-Alignment Film" Functional Material, Vol.17 (1997), No. 11, p.13-22

An object of the present invention is to suppress the occurrence of afterimages after AC driving due to insufficient anisotropy in the alignment direction of the liquid crystal alignment film obtained by the photo-alignment method.

　式中、Ｒ_１及びＲ_２は、それぞれ独立して、単結合、－Ｏ－、－Ｓ－、－ＮＲ_１２－、エステル結合、アミド結合、チオエステル結合、ウレア結合、カーボネート結合、又はカルバメート結合である。Ｒ_１２は、水素原子、又はメチル基である。Ａは炭素数１又は２のアルキレン基である。Ｂ_１及びＢ_２は同じ構造を有し、かつ下記構造から選ばれる２価の有機基である。

　式中、Ｒ_４は、炭素数１～５のアルキレン基である。Ｒ_５は水素原子、メチル基、ヒドロキシ基又はメトキシ基である。 The present inventors have completed the present invention as a result of intensive studies to solve the above problems. That is, the present invention is as follows.
A liquid crystal aligning agent containing in the main chain at least one polymer selected from the group consisting of a polyimide precursor having a structure represented by the following formula (1) and an imidized polymer of the polyimide precursor.

In the formula, R ₁ and R ₂ are each independently a single bond, —O—, —S—, —NR ₁₂ —, ester bond, amide bond, thioester bond, urea bond, carbonate bond, or carbamate bond. is there. R ₁₂ is a hydrogen atom or a methyl group. A is an alkylene group having 1 or 2 carbon atoms. B ₁ and B ₂ are divalent organic groups having the same structure and selected from the following structures.

In the formula, R ₄ is an alkylene group having 1 to 5 carbon atoms. R ₅ is a hydrogen atom, a methyl group, a hydroxy group or a methoxy group.

By using the liquid crystal aligning agent of the present invention, it becomes possible to obtain a liquid crystal aligning film having a high liquid crystal aligning property and capable of suppressing the generation of an AC afterimage.
By using the liquid crystal aligning agent of the present invention, it is not always clear why the above effects are obtained, but the chemical structure of the diamine used as the raw material of the polymer constituting the liquid crystal aligning material is rigid, and It is presumed that it has a symmetrical structure.

　上記式（１）において、Ｒ_１及びＲ_２は、それぞれ独立して、単結合、－Ｏ－、－Ｓ－、－ＮＲ_１２－、エステル結合、アミド結合、チオエステル結合、ウレア結合、カーボネート結合、又はカルバメート結合であり、Ｒ_１２は、水素原子又はメチル基である。Ａは炭素数１又は２のアルキレン基である。Ｂ_１及びＢ_２は、同じ構造を有し、かつ下記構造から選ばれる２価の有機基である。Ｂ_１とＢ_２は同じ構造を有することにより、高い液晶配向性を有する液晶配向膜を得ることができる。 <Specific structure>
The specific structure represented by the above formula (1) (hereinafter, also referred to as a specific structure) is contained in the main chain of the polymer constituting the liquid crystal aligning agent of the present invention.

In the above formula (1), R ₁ and R ₂ are each independently a single bond, —O—, —S—, —NR ₁₂ —, ester bond, amide bond, thioester bond, urea bond, carbonate bond, Alternatively, it is a carbamate bond, and R ₁₂ is a hydrogen atom or a methyl group. A is an alkylene group having 1 or 2 carbon atoms. B ₁ and B ₂ are divalent organic groups having the same structure and selected from the following structures. Since B ₁ and B ₂ have the same structure, a liquid crystal alignment film having high liquid crystal alignment can be obtained.

　上記式中、Ｒ_４は、炭素数１～５のアルキレン基である。Ｒ_５は水素原子、メチル基、ヒドロキシ基又はメトキシ基である。）

In the above formula, R ₄ is an alkylene group having 1 to 5 carbon atoms. R ₅ is a hydrogen atom, a methyl group, a hydroxy group or a methoxy group. )

In the above formula (1), R ₁ and R ₂ are preferably a single bond, —O—, —S—, —NR ₁₂ —, an ester bond or an amide bond, from the viewpoint of liquid crystal alignment. -O- is particularly preferable. From the viewpoint of liquid crystal alignment, R ₁₂ is preferably a hydrogen atom or a methyl group. Further, A is preferably an alkylene group having a carbon chain 2 from the viewpoint of liquid crystal alignment.
From the viewpoint of liquid crystal orientation, B ₁ and B ₂ are preferably biphenylene groups.
In the above formula, R ₄ is preferably an alkylene group having 1 to 3 carbon atoms from the viewpoint of liquid crystal alignment. From the viewpoint of liquid crystal alignment, R ₅ is preferably a hydrogen atom or a methyl group.
The specific structure described above is preferably contained in the diamine which is the raw material of the polyimide precursor. Specific examples of the diamine having the above-mentioned specific structure include, but are not limited to, the following diamines. The polyimide precursor is preferably obtained by polymerizing a diamine component containing at least one diamine selected from the following diamines and a tetracarboxylic acid component.

　（Ｒ_５は、前記と同定義である。）

(R ₅ has the same definition as above.)

　上記式において、Ｒ_５及びＲ_１２は、それぞれの好ましい例も含めて、前記と同定義である。

In the above formula, R ₅ and R ₁₂ have the same definitions as above, including the respective preferable examples.

　上記式中、Ｒ_１、Ｒ_２、Ａは、それぞれの好ましい例を含めて、上記したとおりである。上記特定構造を有するジアミンとしては、なかでも、以下のジアミンが好ましい。

The diamine having the above-mentioned specific structure is preferably a diamine in which amino groups are bound to both ends of the above-mentioned specific structure, and among them, from the viewpoint of alignment properties and reduction of bright spots in a liquid crystal display device, the following diamines are used. Is preferred.

In the above formula, R ₁ , R ₂ , and A are as described above, including preferred examples thereof. As the diamine having the above specific structure, the following diamines are preferable.

<Polymer>
The polyimide precursor constituting the liquid crystal aligning agent of the present invention contains a structural unit represented by the following formula (2).

X ₁ is at least one selected from the group consisting of structures represented by the following formulas (X1-1) and (X1-2). Among them, the following formula (X1-2) is preferable from the viewpoint of liquid crystal alignment.

Y ₁ is a divalent organic group represented by the formula (1).
R ₃ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. Specific examples thereof include a methyl group, an ethyl group, a propyl group, an i-propyl group, an n-butyl group, an i-butyl group, an s-butyl group, a t-butyl group and an n-pentyl group. From the viewpoint of ease of imidization by heating, R ₃ is preferably a hydrogen atom or a methyl group.

Z ₁ and Z ₂ are each independently a hydrogen atom or 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. It is a base. Specific examples of the alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, a t-butyl group, a hexyl group, an octyl group, a decyl group, a cyclopentyl group, a cyclohexyl group and a bicyclohexyl group. Alkenyl groups include those in which one or more CH ₂ —CH ₂ structures present in the above alkyl groups have been replaced with a CH═CH structure. 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, A cyclohexenyl group etc. are mentioned. Examples of the alkynyl group include those in which one or more CH ₂ —CH ₂ structures present in the above alkyl group are replaced with a C≡C structure. Specific examples thereof include an ethynyl group, a 1-propynyl group and a 2-propynyl group.

The above alkyl group, alkenyl group, and alkynyl group may have a substituent, and depending on the substituent, a ring structure may be formed. In addition, forming a ring structure by a substituent means that the substituents are bonded to each other or a part of the mother 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 phosphoric ester group, an amide group, an alkyl group. Group, alkenyl group, alkynyl group and the like.
Examples of the halogen group include a fluorine atom, a chlorine atom, a bromine atom or an iodine atom.
A phenyl group is mentioned as an aryl group. This aryl group may be further substituted with another substituent described above.

The organooxy group can have a structure represented by —OR. The R may be the same or different, and examples thereof include the above-mentioned alkyl group, alkenyl group, alkynyl group and aryl group. These R may be further substituted with the above-mentioned substituents. Specific examples thereof include a methoxy group, an ethoxy group, a propyloxy group, a butoxy group, a pentyloxy group, a hexyloxy group, a heptyloxy group and an octyloxy group.
The organothio group can have a structure represented by —SR. Examples of R include the alkyl group, alkenyl group, alkynyl group, and aryl group described above. These R may be further substituted with the above-mentioned substituents. Specific examples thereof include a methylthio group, an ethylthio group, a propylthio group, a butylthio group, a pentylthio group, a hexylthio group, a heptylthio group and an octylthio group.

The organosilyl group can have a structure represented by —Si— (R) ₃ . The R's may be the same or different, and examples thereof include the above-mentioned alkyl group, alkenyl group, alkynyl group and aryl group. These R may be further substituted with the above-mentioned substituents. Specific examples include a trimethylsilyl group, a triethylsilyl group, a tripropylsilyl group, a tributylsilyl group, a tripentylsilyl group, a trihexylsilyl group, a pentyldimethylsilyl group and a hexyldimethylsilyl group.
The acyl group can have a structure represented by —C (O) —R. Examples of R include the alkyl group, alkenyl group, and aryl group described above. These R may be further substituted with the above-mentioned substituents. Specific examples thereof include a formyl group, an acetyl group, a propionyl group, a butyryl group, an isobutyryl group, a valeryl group, an isovaleryl group and a benzoyl group.

As the ester group, a structure represented by -C (O) OR or -OC (O) -R can be shown. Examples of R include the alkyl group, alkenyl group, alkynyl group, and aryl group described above. These R may be further substituted with the above-mentioned substituents.
The thioester group can have a structure represented by -C (S) OR or -OC (S) -R. Examples of R include the alkyl group, alkenyl group, alkynyl group, and aryl group described above. These R may be further substituted with the above-mentioned substituents.
The phosphate group can have a structure represented by —OP (O) — (OR) ₂ . The R's may be the same or different, and examples thereof include the above-mentioned alkyl group, alkenyl group, alkynyl group and aryl group. These R may be further substituted with the above-mentioned substituents.

The amide group has a structure represented by -C (O) NH ₂ , -C (O) NHR, -NHC (O) R, -C (O) N (R) ₂ or -NRC (O) R. Can be shown. The R's may be the same or different, and examples thereof include the above-mentioned alkyl group, alkenyl group, alkynyl group and aryl group. These R may be further substituted with the above-mentioned substituents.
As the aryl group, the same aryl groups as described above can be mentioned. This aryl group may be further substituted with another substituent described above.
As the alkyl group, the same ones as those mentioned above can be mentioned. The alkyl group may be further substituted with the other substituent described above.
As the alkenyl group, the same alkenyl groups as mentioned above can be mentioned. This alkenyl group may be further substituted with the other substituent described above.
As the alkynyl group, the same alkynyl groups as described above can be mentioned. This alkynyl group may be further substituted with the other substituent described above.

In general, when a bulky structure is introduced, reactivity of an amino group and liquid crystal alignment may be deteriorated. Therefore, Z ₁ and Z _{2 each} have a hydrogen atom or a carbon number of 1 which may have a substituent. Alkyl groups of to 5 are more preferable, and hydrogen atom, methyl group or ethyl group is particularly preferable.
The structural unit represented by the above formula (2) is preferably contained in an amount of 20 to 100 mol% based on all structural units, and from the viewpoint of liquid crystal alignment, 30 to 100 mol% is particularly preferable.

　Ｒ_３、Ｚ_１及びＺ_２の定義は、上記式（２）におけるのと同じである。 <Other structural units>
When the polymer constituting the liquid crystal aligning agent of the present invention contains a structural unit other than the structural unit of the above formula (2), the structural unit is represented by the following formula (3).

The definitions of R ₃ , Z ₁ and Z ₂ are the same as in the above formula (2).

X ₂ is a tetravalent organic group, and Y ₂ is a divalent organic group.
X ₂ is a tetravalent organic group derived from a tetracarboxylic acid derivative, and its structure is not particularly limited. Two or more types of X ₂ may be mixed in the polyimide precursor. Specific examples of X ₂ include the structures of the following formulas (X-1) to (X-44).

R ₈ to R ₁₁ 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, or an alkyl group having 2 to 6 carbon atoms. It is an alkynyl group or a phenyl group. When R ₈ to R ₁₁ have a bulky structure, the liquid crystal alignment may be deteriorated, and therefore a hydrogen atom, a methyl group or an ethyl group is more preferable, and a hydrogen atom or a methyl group is particularly preferable.

In the formula (3), Y ₂ is a divalent organic group derived from diamine, and its structure is not particularly limited. Specific examples of the structure of Y ₂ include the following (Y-1) to (Y-118).

(In the formula (Y-109), m and n are each independently an integer of 1 to 11, m + n is an integer of 2 to 12, and in the formula (Y-114), h is 1 to 3 And j is an integer of 0 to 3 in formulas (Y-111) and (Y-117).
The polyimide precursor used in the present invention is obtained from the reaction of a diamine component and a tetracarboxylic acid derivative, and examples thereof include polyamic acid and polyamic acid ester.

<Polyimide precursor (polyamic acid)>
The polyamic acid, which is the polyimide precursor used in the present invention, is produced by the following method.
Specifically, tetracarboxylic dianhydride and diamine are reacted in the presence of an organic solvent at −20 to 150 ° C., preferably 0 to 50 ° C. for 30 minutes to 24 hours, preferably 1 to 12 hours. Can be synthesized.

The reaction between the diamine component and the tetracarboxylic acid component is usually performed in an organic solvent. The organic solvent used at that time is not particularly limited as long as it can dissolve the generated polyimide precursor. Specific examples of the organic solvent used in the reaction are shown below, but the invention is not limited to these examples. Examples include N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, γ-butyrolactone, N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide or 1,3-dimethyl-imidazolidinone. Be done.
When the polyimide precursor has high solubility, it is represented by methyl ethyl ketone, cyclohexanone, cyclopentanone, 4-hydroxy-4-methyl-2-pentanone or the following formulas [D-1] to [D-3]. The organic solvent used 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。

In the formula [D-1], D ¹ represents an alkyl group having 1 to 3 carbon atoms, in the formula [D-2], D ² represents an alkyl group having 1 to 3 carbons, and the formula [D-3] Among them, D ³ represents an alkyl group having 1 to 4 carbon atoms.

These solvents may be used alone or in combination. Furthermore, even a solvent that does not dissolve the polyimide precursor may be used as a mixture with the solvent as long as the generated polyimide precursor does not precipitate. Further, water in the solvent inhibits the polymerization reaction and causes hydrolysis of the formed polyimide precursor, and therefore it is preferable to use a dehydrated and dried solvent.
The concentration of the polyamic acid polymer in the reaction system is preferably 1 to 30% by mass, and more preferably 5 to 20% by mass from the viewpoint that polymer precipitation does not easily occur and a high molecular weight polymer is easily obtained.

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. Further, 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, and examples thereof include water, methanol, ethanol, hexane, butyl cellosolve, acetone, and toluene.

<Polyimide precursor (polyamic acid ester)>
The polyamic acid ester, which is the polyimide precursor used in the present invention, can be produced by the following production method (1), (2) or (3).

(1) When produced from polyamic acid The polyamic acid ester can be produced by esterifying the polyamic acid produced as described above. Specifically, it is produced 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 1 to 4 hours. be able to.

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 Dineopentylbutyl 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 can be mentioned. The addition amount of the esterifying agent is preferably 2 to 6 molar equivalents with respect to 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, dimethyl sulfoxide or 1,3-dimethyl- Examples include imidazolidinone. When the polyimide precursor has high solubility in a solvent, methyl ethyl ketone, cyclohexanone, cyclopentanone, 4-hydroxy-4-methyl-2-pentanone, or the above formula [D-1] to formula [D-3] is used. The indicated solvents can be used.
These solvents may be used alone or as a mixture. Furthermore, even a solvent that does not dissolve the polyimide precursor may be used as a mixture with the solvent as long as the generated polyimide precursor does not precipitate. Further, since water in the solvent hinders the polymerization reaction and causes hydrolysis of the generated polyimide precursor, it is preferable to use a dehydrated and dried solvent.

The solvent used in the above reaction is preferably N, N-dimethylformamide, N-methyl-2-pyrrolidone, or γ-butyrolactone because of the solubility of the polymer. These are used alone or in combination of two or more. Good. The concentration at the time of production is preferably 1 to 30% by mass, more preferably 5 to 20% by mass, because precipitation of a polymer is less likely to occur and a high molecular weight product is easily obtained.

(2) When produced by reaction of tetracarboxylic acid diester dichloride and diamine The polyamic acid ester can be produced from tetracarboxylic acid diester dichloride and diamine.
Specifically, tetracarboxylic acid diester dichloride and diamine are added in the presence of a base and an organic solvent at −20 to 150 ° C., preferably 0 to 50 ° C. for 30 minutes to 24 hours, preferably 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 added is preferably 2 to 4 times the molar amount of the tetracarboxylic acid diester dichloride from the viewpoints of easy removal and easily obtaining a high molecular weight product.
The solvent used in the above reaction is preferably N-methyl-2-pyrrolidone or γ-butyrolactone in view of the solubility of the monomer and polymer, and these may be used alone or in combination of two or more. The polymer concentration during production is preferably 1 to 30% by mass, and more preferably 5 to 20% by mass, because precipitation of the polymer is less likely to occur and a high molecular weight product is easily obtained. Further, in order to prevent the hydrolysis of the tetracarboxylic acid diester dichloride, the solvent used for the production of the polyamic acid ester is preferably dehydrated as much as possible, and it is preferable to prevent the entry of outside air in a nitrogen atmosphere.

(3) When produced from tetracarboxylic acid diester and diamine The polyamic acid ester can be produced by polycondensing the tetracarboxylic acid diester and diamine.
Specifically, a tetracarboxylic acid diester and a diamine are mixed in the presence of 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 It can be produced by reacting for 15 hours.

Examples of the condensing agent include triphenyl phosphite, dicyclohexylcarbodiimide, 1-ethyl-3- (3-dimethylaminopropyl) carbodiimide hydrochloride, N, N'-carbonyldiimidazole, dimethoxy-1,3,5-triazine. Nylmethylmorpholinium, 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 amount of the condensing agent added is preferably 2 to 3 times the mol of the tetracarboxylic acid diester.

As the base, tertiary amines such as pyridine and triethylamine can be used. The amount of the base added is preferably 2 to 4 times the molar amount of the diamine component from the viewpoint of easy removal and easy production of a high molecular weight product.
Further, in the above reaction, the reaction proceeds efficiently by adding Lewis acid as an additive. As the Lewis acid, lithium halides such as lithium chloride and lithium bromide are preferable. The Lewis acid is preferably added in an amount of 0 to 1.0 times the mol of the diamine component.

Among the above three methods for producing a polyamic acid ester, the production method (1) or (2) is particularly preferable because a high molecular weight polyamic acid ester can be obtained.
The solution of the polyamic acid ester obtained as described above can be poured into a poor solvent while stirring well to precipitate the polymer. Precipitation is carried out several times, and after washing with a poor solvent, it is dried at room temperature or by heating to obtain a purified polyamic acid ester powder. The poor solvent is not particularly limited, and examples thereof include water, methanol, ethanol, hexane, butyl cellosolve, acetone, and toluene.

<Polyimide>
The polyimide used in the present invention can be produced by imidizing the above-mentioned polyamic acid ester or polyamic acid.
When a polyimide is produced from a polyamic acid ester, chemical imidization by adding a basic catalyst to a polyamic acid ester solution or a polyamic acid solution obtained by dissolving a polyamic acid ester resin powder in an organic solvent is simple. Chemical imidation is preferable because the imidization reaction proceeds at a relatively low temperature and the decrease in the molecular weight of the polymer does not easily occur during the imidization process.

The chemical imidization can be performed by stirring the polyamic acid ester to be imidized in an organic solvent in the presence of a basic catalyst. As the organic solvent, the solvent used in the above-mentioned polymerization reaction can be used. Examples of the basic catalyst include pyridine, triethylamine, trimethylamine, tributylamine, trioctylamine and the like. Of these, triethylamine is preferable because it has a basicity sufficient to allow the reaction to proceed.
The temperature at which the imidization reaction is carried out is −20 to 140 ° C., preferably 0 to 100 ° C., and the reaction time is preferably 1 to 100 hours. The amount of the basic catalyst is 0.5 to 30 times, preferably 2 to 20 times the amount of the amic acid ester group. The imidation ratio of the obtained polymer can be controlled by adjusting the amount of catalyst, temperature, reaction time and the like. Since the added catalyst and the like remain in the solution after the imidization reaction, the resulting imidized polymer is recovered by the means described below and redissolved in an organic solvent to obtain the liquid crystal alignment of the present invention. It is preferable to use it as an agent.

When a polyimide is produced from a polyamic acid, chemical imidization by adding a catalyst to a solution of the polyamic acid obtained by the reaction of a diamine component and a tetracarboxylic dianhydride is simple. Chemical imidization is preferable because the imidization reaction proceeds at a relatively low temperature and the decrease in the molecular weight of the polymer does not easily occur in the process of imidization.
The chemical imidization can be performed by stirring the polyamic acid to be imidized in an organic solvent in the presence of a basic catalyst and an acid anhydride. As the organic solvent, the solvent used in the above-mentioned polymerization reaction can be used. Examples of the basic catalyst include pyridine, triethylamine, trimethylamine, tributylamine, trioctylamine and the like. Of these, pyridine is preferable because it has a proper basicity for proceeding the reaction. Examples of the acid anhydride include acetic anhydride, trimellitic anhydride, pyromellitic anhydride and the like. Of these, acetic anhydride is preferable because it facilitates purification after the reaction.

The temperature at which the imidization reaction is carried out is −20 to 140 ° C., preferably 0 to 100 ° C., and the reaction time is preferably 1 to 100 hours. The amount of the basic catalyst is 0.5 to 30 times, preferably 2 to 20 times the amount of the amic acid group, and the amount of the acid anhydride is 1 to 50 times, preferably 3 to the molar amount of the amic acid group. It is 30 mol times. The imidation ratio of the obtained polymer can be controlled by adjusting the amount of catalyst, temperature, reaction time and the like.

In the solution after imidization reaction of polyamic acid ester or polyamic acid, the added catalyst and the like remain, so by the means described below, the obtained imidized polymer is recovered and redissolved in an organic solvent. Therefore, the liquid crystal aligning agent of the present invention is preferable.
The polymer can be precipitated by injecting the solution of the polyimide obtained as described above into a poor solvent while stirring well. Precipitation is performed several times, washed with a poor solvent, and then dried at room temperature or by heating to obtain a purified polyimide powder.
The poor solvent is not particularly limited, but includes methanol, acetone, hexane, butyl cellosolve, heptane, methyl ethyl ketone, methyl isobutyl ketone, ethanol, toluene, benzene and the like.

<Liquid crystal aligning agent>
The liquid crystal aligning agent of the present invention contains at least one polymer selected from the group consisting of a polyimide precursor having a specific structure in the main chain and an imidized polymer of the polyimide precursor. The weight average molecular weight (Mw) of the polymer is preferably 2,000 to 500,000, more preferably 5,000 to 300,000, and further preferably 10,000 to 100,000. The number average molecular weight (Mn) is preferably 1,000 to 250,000, more preferably 2,500 to 150,000, and further preferably 5,000 to 50,000. ..

The concentration of the polymer in the liquid crystal aligning agent of the present invention can be appropriately changed depending on the setting of the thickness of the coating film to be formed, but from the viewpoint of forming a uniform and defect-free coating film, It is preferably not less than 10% by mass, and more preferably not more than 10% by mass from the viewpoint of storage stability of the solution. The concentration of the polymer is preferably 2 to 7% by mass.

The organic solvent that dissolves the polymer (hereinafter, also referred to as a good solvent) contained in the liquid crystal aligning agent used in the present invention is not particularly limited as long as the polymer can be uniformly dissolved therein.
For example, N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, dimethyl sulfoxide, γ-butyrolactone, 1,3-dimethyl-imidazolidinone, methyl ethyl ketone , Cyclohexanone, cyclopentanone or 4-hydroxy-4-methyl-2-pentanone. Among them, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, or γ-butyrolactone is preferably used.
Further, when the polymer of the present invention has high solubility in a solvent, it is preferable to use the solvent represented by the above formulas [D-1] to [D-3].
The content of the good solvent in the liquid crystal aligning agent of the present invention is preferably 20 to 99 mass% of the whole solvent contained in the liquid crystal aligning agent. Above all, 20 to 90 mass% is preferable. More preferably, it is 30 to 80% by mass.

As the liquid crystal aligning agent of the present invention, a solvent (also referred to as a poor solvent) that improves the coating property and surface smoothness of the liquid crystal aligning film when the liquid crystal aligning agent is applied can be used. Specific examples of the poor solvent will be given.
For example, ethanol, isopropyl alcohol, 1-butanol, 2-butanol, isobutyl alcohol, tert-butyl alcohol, 1-pentanol, 2-pentanol, 3-pentanol, 2-methyl-1-butanol, isopentyl alcohol, tert-pentyl alcohol, 3-methyl-2-butanol, neopentyl alcohol, 1-hexanol, 2-methyl-1-pentanol, 2-methyl-2-pentanol, 2-ethyl-1-butanol, 1-heptanol , 2-heptanol, 3-heptanol, 1-octanol, 2-octanol, 2-ethyl-1-hexanol, cyclohexanol, 1-methylcyclohexanol, 2-methylcyclohexanol, 3-methylcyclohexanol, 1,2- Etanji 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentane Diol, 2-methyl-2,4-pentanediol, 2-ethyl-1,3-hexanediol, dipropyl ether, dibutyl ether, dihexyl ether, dioxane, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, 1,2-butoxyethane, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol methyl ethyl ether, diethylene glycol dibutyl ether, 2-pentanone, 3-pentanone, 2-hexanone, 2 Heptanone, 4-heptanone, 3-ethoxybutyl acetate, 1-methylpentyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, ethylene glycol monoacetate, ethylene glycol diacetate, propylene carbonate, ethylene carbonate , 2- (methoxymethoxy) ethanol, ethylene glycol monobutyl ether, ethylene glycol monoisoamyl ether, ethylene glycol monohexyl ether, 2- (hexyloxy) ethanol, furfuryl alcohol, diethylene glycol, propylene glycol, propylene glycol monobutyl ether, 1- (Butoxyethoxy) propanol, propylene glycol monomethyl ether acetate, dipropylene glycol, Dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol dimethyl ether, tripropylene glycol monomethyl ether, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, ethylene glycol monoacetate Tart, ethylene glycol diacetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, 2- (2-ethoxyethoxy) ethyl acetate, diethylene glycol acetate, triethylene glycol, triethylene glycol monomethyl ether, triethylene glycol Monoethyl ether, milk Methyl, ethyl lactate, methyl acetate, ethyl acetate, n-butyl acetate, propylene glycol monoethyl ether acetate, methyl pyruvate, ethyl pyruvate, methyl 3-methoxypropionate, methyl ethyl 3-ethoxypropionate, 3-methoxypropione Ethyl acid, 3-ethoxypropionic acid, 3-methoxypropionic acid, propyl 3-methoxypropionate, butyl 3-methoxypropionate, lactic acid methyl ester, lactic acid ethyl ester, lactic acid n-propyl ester, lactic acid n-butyl ester, lactic acid Examples thereof include isoamyl ester and the solvents represented by the above formulas [D-1] to [D-3].

Among them, 1-hexanol, cyclohexanol, 1,2-ethanediol, 1,2-propanediol, propylene glycol monobutyl ether, ethylene glycol monobutyl ether or dipropylene glycol dimethyl ether is preferable.
The content of these poor solvents is preferably 1 to 80% by mass based on the whole solvent contained in the liquid crystal aligning agent. Among them, 10 to 80 mass% is preferable, and 20 to 70 mass% is more preferable.

In addition to the above, the liquid crystal aligning agent of the present invention may be a polymer other than the polymer of the present invention, a dielectric or conductive substance for the purpose of changing the electrical properties such as the dielectric constant and conductivity of the liquid crystal aligning film, and the liquid crystal aligning film. And a silane coupling agent for the purpose of improving the adhesion to the substrate, a crosslinkable compound for the purpose of increasing the hardness and density of the film when it is formed into a liquid crystal alignment film, and further a polyimide precursor when baking the coating film. An imidation promoter for the purpose of efficiently promoting imidization by heating may be added.

<Liquid crystal alignment film>
The liquid crystal alignment film of the present invention is a film obtained by applying the above liquid crystal alignment agent to a substrate, drying and baking. The substrate on which the liquid crystal aligning agent is applied is not particularly limited as long as it is a highly transparent substrate, and a glass substrate, a silicon nitride substrate, an acrylic substrate, a plastic substrate such as a polycarbonate substrate, or the like can be used for driving the liquid crystal. It is preferable to use a substrate on which the ITO electrode or the like is formed from the viewpoint of simplifying the process. Further, in the reflective liquid crystal display element, an opaque material such as a silicon wafer can be used if only one substrate is used, and in this case, a material such as aluminum that reflects light can be used for the electrode.

Examples of the method for applying the liquid crystal aligning agent of the present invention include a spin coating method, a printing method and an inkjet method.
Any temperature and time can be selected for the drying and firing steps after applying the liquid crystal aligning agent. Usually, in order to sufficiently remove the contained organic solvent, the drying temperature is preferably 50 to 120 ° C., and the drying time is preferably 1 to 10 minutes. The firing temperature is preferably 150 to 300 ° C., and the firing time is preferably 5 to 120 minutes.
The thickness of the film after firing is not particularly limited, but if it is too thin, the reliability of the liquid crystal display element may be impaired, so it is preferably 5 to 300 nm, more preferably 10 to 120 nm.

As a method of photo-alignment treatment of the liquid crystal alignment film, the coating film surface is irradiated with radiation polarized in a certain direction, and in some cases, further heat-treated at a temperature of 150 to 250 ° C. to impart liquid crystal alignment ability. There is a method. Ultraviolet rays and visible rays having a wavelength of 100 to 800 nm can be used as the radiation. Among these, ultraviolet rays having a wavelength of 100 to 400 nm are preferable, and those having a wavelength of 200 to 400 nm are particularly preferable. Further, in order to improve the liquid crystal alignment, the coating 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, particularly preferably 100 ~ 5,000mJ / cm ^2. The liquid crystal alignment film manufactured as described above can stably align liquid crystal molecules in a certain direction.
The higher the extinction ratio of polarized ultraviolet light is, the better, since higher anisotropy can be imparted. Specifically, the extinction ratio of linearly polarized ultraviolet light is preferably 10: 1 or more, more preferably 20: 1 or more.

The film irradiated with polarized radiation may then be contact-treated with a solvent containing at least one selected from water and organic solvents.
The solvent used for the contact treatment is not particularly limited as long as it is a solvent that dissolves a decomposition 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, 3- Methyl methoxypropionate, ethyl 3-ethoxypropionate, propyl acetate, butyl acetate, cyclohexyl acetate and the like can be mentioned. Two or more kinds 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. Particularly preferred is water, 2-propanol, or a mixed solvent of water and 2-propanol.

In the present invention, examples of the contact treatment of the film irradiated with polarized radiation and the solution containing an organic solvent include a dipping treatment and a spray (spray) treatment, and treatment for sufficiently contacting the membrane and the liquid. Is preferred. Above all, a method of immersing the membrane in a solution containing an organic solvent for preferably 10 seconds to 1 hour, more preferably 1 to 30 minutes is preferable. The contact treatment may be carried out at room temperature or with heating, but is preferably carried out at 10 to 80 ° C, more preferably 20 to 50 ° C. Moreover, if necessary, a means for enhancing contact with ultrasonic waves or the like can be provided.
After the contact treatment, in order to remove the organic solvent in the used solution, either rinsing or drying with a low boiling point solvent such as water, methanol, ethanol, 2-propanol, acetone, or methyl ethyl ketone, or both, is performed. You can go.

Further, the film subjected to the contact treatment with a 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 150 to 300 ° C. Higher temperature promotes reorientation of molecular chains, but too high temperature may cause decomposition of molecular chains. Therefore, the heating temperature is more preferably 180 to 250 ° C, particularly preferably 200 to 230 ° C.
If the heating time is too short, the effect of reorientation of the molecular chain may not be obtained, and if it is too long, the molecular chain may be decomposed, so that it is preferably 10 seconds to 30 minutes. 10 minutes is more preferred.

<Liquid crystal display element>
The liquid crystal display device of the present invention is a device obtained by preparing a liquid crystal cell by a known method after obtaining a substrate having a liquid crystal alignment film formed from the liquid crystal aligning agent of the present invention, and using the cell as a device. is there.
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 below as an example. 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 that constitutes 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 to display a desired image. Next, an insulating film is provided on each substrate so as to cover the common electrodes and the segment electrodes. The insulating film can be, for example, a film made of SiO ₂ —TiO ₂ formed by the sol-gel method.
Next, the liquid crystal alignment film of the present invention is formed on each substrate. Next, one substrate is placed on the other substrate so that their alignment film surfaces face each other, and the periphery is bonded with a sealing material. In order to control the substrate gap, it is usually preferable to mix a spacer in the sealing material. In addition, it is preferable to disperse spacers for controlling the substrate gap also on the in-plane portion where the sealing material is not provided. In addition, a part of the sealing material is usually provided with an opening that can be filled with liquid crystal from the outside.

Next, a liquid crystal material is injected into the space surrounded by the two substrates and the sealing material through the opening provided in the sealing material. Then, this 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. Next, a polarizing plate is installed. Specifically, a pair of polarizing plates are attached to the surfaces of the two substrates opposite to the liquid crystal layer. The liquid crystal display element of the present invention can be obtained through the above steps.
In the present invention, as the sealant, for example, a resin having a reactive group such as an epoxy group, an acryloyl group, a methacryloyl group, a hydroxy group, an allyl group, or an acetyl group, which is cured by ultraviolet irradiation or heating is used. In particular, it is preferable to use a cured resin system having both reactive groups of epoxy group and (meth) acryloyl group.

An inorganic filler may be added to the above-mentioned sealing agent for the purpose of improving adhesiveness, moisture resistance and the like. The inorganic filler that can be used is not particularly limited, and specifically, spherical silica, fused silica, crystalline silica, titanium oxide, titanium black, silicon carbide, silicon nitride, boron nitride, calcium carbonate, magnesium carbonate, sulfuric acid. Barium, calcium sulfate, mica, talc, clay, alumina, magnesium oxide, zirconium oxide, aluminum hydroxide, calcium silicate, aluminum silicate, lithium aluminum silicate, zirconium silicate, barium titanate, glass fiber, carbon fiber, molybdenum disulfide, Examples include asbestos. Preferably, spherical silica, fused silica, crystalline silica, titanium oxide, titanium black, silicon nitride, boron nitride, calcium carbonate, barium sulfate, calcium sulfate, mica, talc, clay, alumina, aluminum hydroxide, calcium silicate, aluminum silicate. And so on. You may use the said inorganic filler in mixture of 2 or more types.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto. In addition, the abbreviations of the compounds and the measuring methods of the respective properties described below are as follows.
NMP: N-methyl-2-pyrrolidone,
BCS: Butyl cellosolve

　なお、式中、Ｆｍｏｃは、9-フルオレニルメチルオキシカルボニル基を表し、Ｂｏｃは、ｔ－ブトキシカルボニル基を表す。

In the formula, Fmoc represents a 9-fluorenylmethyloxycarbonyl group, and Boc represents a t-butoxycarbonyl group.

[ ¹ H NMR]
Apparatus: Fourier transform type superconducting nuclear magnetic resonance apparatus (FT-NMR) INOVA-400 (manufactured by Varian) 400 MHz
Solvent: Deuterated dimethyl sulfoxide (DMSO-d ₆ ))
Standard substance: Tetramethylsilane (TMS)
Total number of times: 8 or 32

[viscosity]
For the viscosity of the polyimide and polyamic acid solution, an E-type viscometer (VE-22H manufactured by Toki Sangyo Co., Ltd.) was used, and the sample amount was 1.1 mL, cone rotor TE-1 (1 ° 34 ', R24), temperature 25 ° C. It was measured at.

[Production of liquid crystal cell]
A liquid crystal cell having the structure of the FFS mode liquid crystal display device was produced.
First, a substrate with electrodes was prepared. The substrate is a 30 mm × 50 mm rectangular glass plate having a thickness of 0.7 mm. On the substrate, an ITO electrode having a solid pattern, which constitutes a counter electrode as a first layer, is formed. A SiN (silicon nitride) film formed by the CVD method is formed as a second layer on the counter electrode of the first layer. The film thickness of the second-layer SiN film is 500 nm and functions as an interlayer insulating film. A comb-teeth-shaped pixel electrode formed by patterning an ITO film as a third layer is arranged on the second-layer SiN film to form two pixels of a first pixel and a second pixel. ing. The size of each pixel is 10 mm in length and about 5 mm in width. At this time, the first-layer counter electrode and the third-layer pixel electrode are electrically insulated by the action of the second-layer SiN film.

The pixel electrode of the third layer has a comb-tooth shape formed by arranging a plurality of "dogleg" -shaped electrode elements whose central portion is bent at an internal angle of 160 °. The width of each electrode element in the lateral direction is 3 μm, and the distance between the electrode elements is 6 μm. The pixel electrode that forms each pixel is configured by arranging a plurality of curved "dogleg" -shaped electrode elements in the central portion, so the shape of each pixel is not rectangular, but is similar to that of the electrode element. It has a shape that resembles a bold "dogleg" bent at a part. Each pixel is divided into upper and lower parts with a central bent portion as a boundary, and has a first region on the upper side and a second region on the lower side of the bent portion.

Next, after filtering the obtained liquid crystal aligning agent with a filter having a pore size of 1.0 μm, the prepared substrate with electrodes and a glass substrate having a columnar spacer with a height of 4 μm on which an ITO film is formed on the back surface are prepared. It was applied by spin coating. After drying for 2 minutes on a hot plate at 80 ° C., baking was performed for 30 minutes in a hot air circulation type oven at 230 ° C. to form a coating film having a thickness of 100 nm. This coating film surface was irradiated with polarized ultraviolet rays so as to have a dose of 500 mJ / cm ² and subjected to an alignment treatment to obtain a substrate with a liquid crystal alignment film. The liquid crystal alignment film formed on the electrode-attached substrate is a liquid crystal alignment film formed on the second glass substrate by performing alignment treatment so that the direction that equally divides the interior angle of the pixel bend portion and the liquid crystal alignment direction are orthogonal to each other. Is subjected to alignment treatment so that the alignment direction of the liquid crystal on the first substrate and the alignment direction of the liquid crystal on the second substrate coincide with each other when the liquid crystal cell is manufactured. Set the above two substrates as a set, print the sealant on the substrate, and bond the other substrate so that the alignment direction where the liquid crystal alignment film surfaces face each other becomes 0 °, and then cure the sealant. Then, an empty cell was produced. Liquid crystal MLC-3019 (manufactured by Merck Ltd.) was injected into this empty cell by a reduced pressure injection method, and the injection port was sealed to obtain an FFS driven liquid crystal cell. After that, the obtained liquid crystal cell was heated at 110 ° C. for 1 hour, left to stand overnight, and then used for evaluation of afterimage.

[Afterimage evaluation by long-term AC drive]
Using the above liquid crystal cell, an AC voltage of ± 5 V was applied for 120 hours at a frequency of 30 Hz in a constant temperature environment of 60 ° C. Then, the pixel electrode of the liquid crystal cell and the counter electrode were short-circuited and left at room temperature for one day.
After leaving, the liquid crystal cell is placed between two polarizing plates arranged so that their polarization axes are orthogonal to each other, and the backlight is turned on with no voltage applied so that the brightness of the transmitted light is minimized. The arrangement angle of the liquid crystal cell was adjusted. Then, the rotation angle when the liquid crystal cell was rotated from the angle where the second region of the first pixel was darkest to the angle where the first region was darkest was calculated as the angle Δ. Similarly, for the second pixel, the second region and the first region were compared, and the same angle Δ was calculated. Then, the average value of the angle Δ values of the first pixel and the second pixel was calculated as the angle Δ of the liquid crystal cell.
An angle Δ of 0.15 ° or more of the liquid crystal cell obtained above was evaluated as “x”, less than 0.15 ° was evaluated as “Δ”, and less than 0.1 ° was evaluated as “◯”.

(Synthesis Example 1: Synthesis of DA-5)
DA-5 was synthesized by the following procedure.

Synthesis of Compound [1] Ethylene glycol ditosylate (40.6 g, 110 mmol), 4-hydroxy-4′-nitrobiphenyl (49.5 g), and potassium carbonate (37.8 g) with respect to dimethylformamide (500 g). ) Was added and the mixture was stirred at 80 ° C. for 23 hours. After cooling to room temperature, the solution was poured into pure water (1000 g) and stirred to precipitate crystals. The crystals were filtered, the filter cake was slurry-washed with methanol (500 g), filtered, and the filter cake was dried to obtain a crude product (47.6 g). Dimethylformamide (333 g) was added to the crude product, and the mixture was heated and dissolved at 100 ° C., then methanol (333 g) was added and cooled to precipitate crystals. After filtration, the residue was dried to obtain compound [1] (yield: 40.2 g, yield: 80%, yellow crystals).
1H-NMR (400MHz, DMSO-d6, δppm): 8.28 (d, 4H, J = 9.2 Hz), 7.95 (d, 4H, J = 9.2 Hz), 7.80 (d, 4H, J = 9.2 Hz), 7.17 (d, 4H, J = 9.2 Hz), 4.44 (s, 4H).

Synthesis of Compound [DA-5] Compound [1] (40.2 g) and 5% palladium carbon (4.0 g) were added to dimethylformamide (800 g), and the mixture was stirred at 60 ° C. for 19 hours in a hydrogen atmosphere. .. After purging with nitrogen, dimethylformamide (680 g) was added and the diamine was heated and dissolved at 130 ° C., the catalyst was filtered while hot, and the filtrate was partially concentrated to 813 g in the internal volume. Dimethylformamide (60 g) was added and dissolved at 120 ° C., then methanol (838 g) was added and cooled to precipitate crystals. After filtration, the residue was dried to obtain compound [DA-5] (yield: 33.6 g, yield: 96%, ocher crystals).
1H-NMR (400MHz, DMSO-d6, δppm): 7.46 (d, 4H, J = 8.8Hz), 7.29 (d, 4H, J = 8.8Hz), 7.00 (d, 4H, J = 8.8Hz), 6.61 (d, 4H, J = 8.8 Hz), 5.13 (br, 4H), 4.32 (s, 4H).

(Synthesis example 2)
1.30 g (12.0 mmol) of DA-1, 2.93 g (12.0 mmol) of DA-2, and 2.05 g of DA-6 were placed in a 100 mL four-necked flask equipped with a stirrer and a nitrogen introducing tube. (6.00 mmol) was weighed out, and then 77 g of NMP was added and dissolved by stirring while sending nitrogen. While stirring this diamine solution, 6.19 g (27.6 mmol) of DAH-1 was added, NMP was further added so that the solid content concentration was 12% by mass, and the mixture was stirred at 40 ° C. for 12 hours to obtain polyamic acid (PAA-1). A solution of (-1) (viscosity: 340 mPa · s) was obtained.

(Synthesis example 3)
1.17 g (10.8 mmol) of DA-1, 3.46 g (10.8 mmol) of DA-3, and 1.84 g of DA-6 were placed in a 100 mL four-necked flask equipped with a stirrer and a nitrogen introducing tube. (5.39 mmol) was weighed out, and then 75 g of NMP was added and dissolved by stirring while sending nitrogen. While stirring this diamine solution, 5.57 g (24.8 mmol) of DAH-1 was added, NMP was further added so that the solid content concentration was 12% by mass, and the mixture was stirred at 40 ° C. for 12 hours to obtain polyamic acid (PAA-1). A solution of -2) (viscosity: 340 mPa · s) was obtained.

(Synthesis example 4)
1.17 g (10.8 mmol) of DA-1, 4.43 g (10.8 mmol) of DA-4 and 1.84 g of DA-6 were placed in a 200 mL four-necked flask equipped with a stirrer and a nitrogen introducing tube. (5.39 mmol) was weighed out, and then 83 g of NMP was added and dissolved by stirring while feeding nitrogen. 5.75 g (25.7 mmol) of DAH-1 was added to this diamine solution while stirring, and NMP was further added so that the solid content concentration was 12% by mass, and the mixture was stirred at 40 ° C. for 12 hours and then polyamic acid (PAA-1) was added. A solution of (3) (viscosity: 360 mPa · s) was obtained.

(Synthesis example 5)
In a 100 mL four-necked flask equipped with a stirrer and equipped with a nitrogen introduction tube, DA-1 (0.56 g, 5.18 mmol), DA-5 (2.06 g, 5.20 mmol) and DA-6 (0.89 g) were added. (2.61 mmol) was weighed out, then 39 g of NMP was added, and the mixture was dissolved by stirring while feeding nitrogen. While stirring this diamine solution, 2.68 g (12.0 mmol) of DAH-1 was added, NMP was further added so that the solid content concentration was 12% by mass, and the mixture was stirred at 40 ° C. for 12 hours to obtain polyamic acid (PAA). -4) solution (viscosity: 215 mPa · s) was obtained.

(Synthesis example 6)
3.83 g (19.2 mmol) of DA-7 and 1.43 g (4.79 mmol) of DA-8 were weighed into a 100 mL four-necked flask equipped with a stirrer and a nitrogen introducing tube, and then 78 g of NMP. In addition, it was dissolved by stirring while sending nitrogen. While stirring this diamine solution, 6.56 g (22.2 mmol) of DAH-2 was added, NMP was further added so that the solid content concentration was 12% by mass, and the mixture was stirred at 70 ° C. for 20 hours to obtain polyamic acid (PAA). A solution (-5) (viscosity: 420 mPa · s) was obtained.

(Comparative Example 1)
6.25 g of the polyamic acid solution (PAA-1) obtained in Synthesis Example 2 was weighed into a 50 mL Erlenmeyer flask containing a stirring bar. Next, 3.50 g of NMP and 4.5 g of BCS were added and stirred overnight with a magnetic stirrer to obtain a liquid crystal aligning agent (AL-1).

(Comparative example 2)
6.25 g of the polyamic acid solution (PAA-2) obtained in Synthesis Example 3 was weighed into a 50 mL Erlenmeyer flask containing a stirring bar. Then, 3.50 g of NMP and 4.5 g of BCS were added and stirred overnight with a magnetic stirrer to obtain a liquid crystal aligning agent (AL-2).

(Comparative example 3)
6.25 g of the polyamic acid solution (PAA-3) obtained in Synthesis Example 4 was weighed into a 50 mL Erlenmeyer flask containing a stir bar. Next, 3.50 g of NMP and 4.5 g of BCS were added and stirred overnight with a magnetic stirrer to obtain a liquid crystal aligning agent (AL-3).

(Example 1)
6.25 g of the polyamic acid solution (PAA-4) obtained in Synthesis Example 5 was weighed into a 50 mL Erlenmeyer flask containing a stirring bar. Next, 3.50 g of NMP and 4.5 g of BCS were added and stirred overnight with a magnetic stirrer to obtain a liquid crystal aligning agent (AL-4).

(Example 2)
2.50 g of the polyamic acid solution (PAA-4) obtained in Synthesis Example 5 and 3.75 g of the polyamic acid solution (PAA-5) obtained in Synthesis Example 6 were placed in a 50 mL Erlenmeyer flask containing a stirring bar. I took it. 3.50 g of NMP and 4.50 g of BCS were added, 0.75 g of 10% NMP solution of AD-1 and 0.113 g of AD-2 were added, and the mixture was stirred overnight with a magnetic stirrer for liquid crystal aligning agent (AL-5). Got By storing AL-5 in an environment of −20 ° C., the stability during frozen storage was confirmed. After 1 month of frozen storage, it was confirmed that there was no precipitation and the filterability was good.

(Comparative example 4)
The afterimage of the liquid crystal aligning agent (AL-1) obtained in Comparative Example 1 was evaluated by long-term AC driving as described above. That is, a liquid crystal cell having the configuration of the FFS mode liquid crystal display device was prepared by using the liquid crystal aligning agent (AL-1) as described above, and afterimage evaluation by the long-term AC drive was performed on the FFS driven liquid crystal cell. did. As a result, the value of the angle Δ of this liquid crystal cell after long-term AC driving was 0.16 degrees.

(Comparative example 5)
An FFS-driving liquid crystal cell was produced in the same manner as in Comparative Example 4 except that the liquid crystal aligning agent (AL-2) obtained in Comparative Example 2 was used. Afterimage evaluation of the FFS-driving liquid crystal cell by long-term AC driving was performed, and as a result, the value of the angle Δ of the liquid crystal cell after long-term AC driving was 0.11 degree.

(Comparative example 6)
An FFS driven liquid crystal cell was produced in the same manner as in Comparative Example 4 except that the liquid crystal aligning agent (AL-3) obtained in Comparative Example 3 was used. The FFS-driving liquid crystal cell was subjected to afterimage evaluation by long-term AC driving, and as a result, the value of the angle Δ of the liquid crystal cell after long-term AC driving was 0.17 degrees.

(Example 3)
An FFS-driven liquid crystal cell was produced in the same manner as in Comparative Example 4 except that the liquid crystal aligning agent (AL-4) obtained in Example 1 was used. Afterimage evaluation of the FFS-driving liquid crystal cell by long-term AC driving was performed, and as a result, the value of the angle Δ of the liquid crystal cell after long-term AC driving was 0.05 degrees.

(Example 4)
The polymer two-component blend liquid crystal aligning agent (AL-5) obtained in Example 2 was filtered through a filter having a pore size of 1.0 μm, spin-coated on a glass substrate with a transparent electrode, and then on a hot plate at a temperature of 80 ° C. It was dried for 2 minutes. Then, after baking for 30 minutes in an IR oven at a temperature of 230 ° C., an imidized film having a film thickness of 100 nm was obtained. When the state of the fired film was confirmed, it was confirmed that the film was uniformly formed without unevenness or cissing.

Table 1 summarizes the results of afterimage evaluation of the liquid crystal aligning agents of Comparative Examples 4 to 6 and Example 3 by long-term AC driving.

In addition, the entire contents of the specification, claims and abstract of Japanese Patent Application No. 2018-209060 filed on November 6, 2018 are incorporated herein as disclosure of the specification of the present invention. It is a thing.

Claims (14)

A liquid crystal aligning agent containing in the main chain at least one polymer selected from the group consisting of a polyimide precursor having a structure represented by the following formula (1) and an imidized polymer of the polyimide precursor.

(In the formula, R ₁ and R ₂ are each independently a single bond, —O—, —S—, —NR ₁₂ —, ester bond, amide bond, thioester bond, urea bond, carbonate bond, or carbamate bond. And R ₁₂ is a hydrogen atom or a methyl group, A is an alkylene group having 1 or 2 carbon atoms, B ₁ and B ₂ have the same structure, and are a divalent organic group selected from the following structures. It is a base.)

(In the formula, R ₄ is an alkylene group having 1 to 5 carbon atoms. R ₅ is a hydrogen atom, a methyl group, a hydroxy group or a methoxy group.) In the formula (1), R ₁ and R ₂ are each independently a single bond, —O—, —S—, —NR ₁₂ —, an ester bond or an amide bond, and A is a carbon chain 2 The liquid crystal aligning agent according to claim 1, which is an alkylene group, R ₄ is an alkylene group having 1 to 3 carbon atoms, and R ₅ is a hydrogen atom or a methyl group. The liquid crystal aligning agent according to claim 1, wherein the polyimide precursor is a polymer containing a structural unit represented by the following formula (2).

(In the formula, X ₁ is at least one selected from the group consisting of structures represented by the following formulas (X1-1) and (X1-2). Y ₁ is represented by the formula (1). R ₃ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and Z ₁ and Z ₂ may each independently have a hydrogen atom or a substituent. , An 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.)

The liquid crystal aligning agent according to any one of claims 1 to 3, wherein the polyimide precursor is obtained by polymerizing a diamine component and a tetracarboxylic acid component. The liquid crystal aligning agent according to claim 4, wherein the diamine component contains at least one diamine selected from the following.

(R ₅ and R ₁₂ are the same as those in the above formula (1).) The liquid crystal aligning agent according to any one of claims 3 to 5, wherein the polyimide precursor has a structural unit represented by the formula (2) in an amount of 20 to 100 mol% based on all structural units. 7. The liquid crystal aligning agent according to claim 3, wherein in the formula (2), X ₁ is the following formula (X1-2).

In the above formula (2), R ₃ is a hydrogen atom or a methyl group, and Z ₁ and Z ₂ are a hydrogen atom or an optionally substituted alkyl group having 1 to 5 carbon atoms. Item 8. The liquid crystal aligning agent according to any one of items 3 to 7. 9. The liquid crystal aligning agent according to claim 1, wherein the structure represented by the formula (1) is the following structure.

(In the formula, A, R ₁ and R ₂ have the same definitions as described above.) The liquid crystal aligning agent according to claim 1, wherein the polyimide precursor further contains a structural unit represented by the following formula (3).

(In the formula, the definitions of R ₃ , Z ₁ and Z ₂ are the same as those in the above formula (2). X ₂ is a tetravalent organic group and Y ₂ is a divalent organic group. is there.) The liquid crystal aligning agent according to any one of claims 1 to 10, wherein the concentration of the polymer is 1% by mass or more and 10% by mass or less based on the total amount of the liquid crystal aligning agent. A liquid crystal alignment film obtained by irradiating a film obtained by applying and baking the liquid crystal alignment agent according to any one of claims 1 to 11 with polarized ultraviolet light. A liquid crystal display device comprising the liquid crystal alignment film according to claim 12. A diamine represented by the following formula.

(In the formula, R ₁ and R ₂ are each independently a single bond, —O—, —S—, —NR ₁₂ —, ester bond, amide bond, thioester bond, urea bond, carbonate bond, or carbamate bond. And R ₁₂ is a hydrogen atom or a methyl group, and A is an alkylene group having 1 or 2 carbon atoms.)