CN109923469B

CN109923469B - Liquid crystal aligning agent, liquid crystal alignment film, and liquid crystal display element

Info

Publication number: CN109923469B
Application number: CN201780069120.9A
Authority: CN
Inventors: 石川和典; 金信郁; 中原翔一朗
Original assignee: Nissan Chemical Corp
Current assignee: Nissan Chemical Corp
Priority date: 2016-09-13
Filing date: 2017-09-08
Publication date: 2022-06-28
Anticipated expiration: 2037-09-08
Also published as: TW201823436A; KR102393693B1; WO2018051923A1; JP7089227B2; CN109923469A; JPWO2018051923A1; KR20190053904A

Abstract

A liquid crystal aligning agent contains the following components (A) and (B). The definitions of the symbols in the following formulae are as described in the specification. (A) The components: at least 1 polymer 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, and a component (B): a compound having 2 or more partial structures represented by the following formula (2) and having a molecular weight of 2500 or less.

Description

Liquid crystal aligning agent, liquid crystal alignment film, and liquid crystal display element

Technical Field

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

Background

Liquid crystal display elements are now widely used as display devices that achieve thin and light weight. In general, in the liquid crystal display element, a liquid crystal alignment film is used to determine the alignment state of liquid crystal.

As a polymer used for a liquid crystal alignment film, polyimide, polyamide, polyamideimide, and the like are known, and a liquid crystal alignment agent obtained by dissolving these polymers and their precursors in a solvent is generally used.

In recent years, liquid crystal televisions with large screens and high definition have been widely put into practical use, and liquid crystal display elements for such applications are required to have characteristics capable of withstanding long-term use in harsh environments. Therefore, the liquid crystal alignment film used here needs to have higher reliability than conventional ones. In order to solve such a problem, a liquid crystal aligning agent using a specific additive has been proposed (see patent document 1).

Documents of the prior art

Patent literature

Patent document 1: international publication No. 2010/074269

Disclosure of Invention

Problems to be solved by the invention

Recently, the luminance of the Backlight (BL) used in the liquid crystal display element has been further increased, and excellent light resistance and relaxation characteristics far exceeding conventional levels are also required for the alignment stability and electrical characteristics of the liquid crystal alignment film.

Means for solving the problems

The present inventors have conducted extensive studies and, as a result, have found that the above problems can be solved by a liquid crystal aligning agent containing a polymer selected from the group consisting of a polyimide precursor obtained by reacting a diamine component containing a diamine having a specific structure with a tetracarboxylic acid derivative component, and a polyimide ring-closed from the polyimide precursor, and a compound having a specific structure.

The invention of claim 1 to achieve the above object is a liquid crystal aligning agent containing the following components (a) and (B).

(A) The components: at least 1 polymer 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

(in the formula (1), R₁Represents hydrogen or a 1-valent organic group. Q₁Represents an alkylene group having 1 to 5 carbon atoms. Cy is a 2-valent group representing an aliphatic heterocyclic ring containing azetidine, pyrrolidine, piperidine or hexamethyleneimine, to the ring portion of which a substituent is optionally bonded. R₂And R₃Each independently is a 1-valent organic group. q and r are each independently an integer of 0 to 4. Wherein when the sum of q and R is 2 or more, a plurality of R₂And R₃Having the above definition. )

(B) The components: a compound having 2 or more structures represented by the following formula (2) and having a molecular weight of 2500 or less

(in the formula (2), R¹R represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms²And R³Each independently represents a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or³-CH₂-O-R¹¹(R¹¹Represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms ″) ³"represents and R²And R³The linkage of the bonded carbon atoms), ", or¹"and²"denotes a bond to another atom. )

The invention of claim 2 to achieve the above object is a liquid crystal aligning agent of claim 1, wherein the diamine of the formula (1) is represented by the following formula (3).

(in the formula (3), R₁Is a hydrogen atom, a methyl group or a tert-butoxycarbonyl group, R₂And R₃Each independently being a hydrogen atom or a methyl group, Q₁Is a C1-5 linear alkylene group. )

The 3 rd aspect of the present invention to achieve the above object is the liquid crystal aligning agent of the 1 st or 2 nd aspect, wherein the content ratio of the diamine represented by the above formula (1) is 1 to 80 mol% based on 1 mol of the total diamine components.

The 4 th aspect of the present invention to achieve the above object is the liquid crystal aligning agent according to any one of the 1 st to 3 rd aspects, wherein the compound of the component (B) is at least one compound selected from the following formulae.

The 5 th aspect of the present invention to achieve the above object is the liquid crystal aligning agent of the 1 st to 4 th aspects, further comprising a polyimide precursor containing a structural unit of the following formula (5) as a component (C).

(in the formula (5), X₂Is a 4-valent organic radical derived from a tetracarboxylic acid derivative, Y₂Is a 2-valent organic radical derived from a diamine, R ₄Is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, Z₁And Z₂Each independently represents 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. )

The invention according to claim 6 to 5 is a liquid crystal aligning agent containing X in the formula (5)₂A polyimide precursor which is a structural unit having the following structure.

The 7 th aspect of the present invention to achieve the above object is a liquid crystal alignment film obtained from the liquid crystal aligning agent according to any one of the 1 st to 6 th aspects.

An 8 th aspect of the present invention to achieve the above object is a liquid crystal display element including the liquid crystal alignment film of the 7 th aspect.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the liquid crystal aligning agent of the present invention, a liquid crystal alignment film having excellent BL resistance, alignment stability, and relaxation properties can be obtained.

Detailed Description

The liquid crystal aligning agent of the present invention contains a component (A) and a component (B). The respective constituent conditions will be described in detail below.

< component (A) >

The component (a) contained in the liquid crystal aligning agent of the present invention refers to at least 1 polymer selected from the group consisting of a polyimide precursor obtained by reacting a diamine component containing a diamine of the following formula (1) (hereinafter also referred to as a specific diamine) with a tetracarboxylic acid derivative component, and a polyimide obtained by ring-closing the polyimide precursor.

In the above formula (1), R₁Represents hydrogen or a 1-valent organic group, preferably a hydrogen atom or a linear alkyl group having 1 to 3 carbon atoms, and more preferably a hydrogen atom or a methyl group.

In addition, R₁The protecting group may be a protecting group which is thermally caused to undergo a leaving reaction and is replaced with a hydrogen atom. From the viewpoint of storage stability of the liquid crystal aligning agent, it is preferable that the protecting group is not removed at room temperature, and is removed at preferably 80 ℃ or higher, more preferably 100 ℃ or higher, and particularly preferably 150 to 200 ℃ to form a hydrogen atom. Examples thereof include 1, 1-dimethyl-2-chloroethoxycarbonyl group, 1-dimethyl-2-cyanoethoxycarbonyl group and tert-butoxycarbonyl group, and tert-butoxycarbonyl group is preferred.

Q₁The alkylene group has 1 to 5 carbon atoms, and is preferably a linear alkylene group having 1 to 5 carbon atoms from the viewpoint of ease of synthesis. Cy is a 2-valent group representing an aliphatic heterocyclic ring containing azetidine, pyrrolidine, piperidine, or hexamethyleneimine, and is preferably azetidine, pyrrolidine, or piperidine, from the viewpoint of ease of synthesis. In addition, substituents may be bonded to the ring portion thereof.

R₂And R₃Each independently is a 1-valent organic group, and q and r are each independently integers of 0 to 4. Wherein when the sum of q and R is 2 or more, a plurality of R ₂And R₃Having the above definition. From synthesisFrom the viewpoint of simplicity, R is preferably₂And R₃Is methyl.

The bonding position of the amino group in the benzene ring constituting the diamine is not limited, but the amino group is preferably located at the 3-position or 4-position with respect to the nitrogen atom on Cy and preferably located at the Q-position₁And R₁The bonded nitrogen atom is located at the 3-or 4-position, more preferably at the 4-position with respect to the nitrogen atom on Cy and with respect to Q₁And R₁The bonded nitrogen atom is in the 4-position.

The structure which is considered to be one of the main causes of the effects of the present invention is considered to be a structure (hereinafter, also referred to as a specific structure) other than 2 primary amino groups from the diamine of the formula (1). From this fact, it is considered that the specific structure can be introduced into the polymer used in the liquid crystal aligning agent of the present invention by using a diamine compound containing 2 or more specific structures, a tetracarboxylic dianhydride having a specific structure, or the like without using the diamine of the above formula (1), but it is preferable to use the diamine of the above formula (1) in view of the synthetic convenience.

The diamine represented by the above formula (1) of the present invention is preferably a compound represented by the following formula (3).

In the above formula (3), R₁Is a hydrogen atom, a methyl group or a tert-butoxycarbonyl group. R₂And R₃Each independently being a hydrogen atom or a methyl group, Q ₁Is a linear alkylene group having 1 to 5 carbon atoms.

Specific examples of the diamine represented by the above formula (3) include diamines represented by the following formulae (3-1) to (3-10). In the following formula, Boc represents a tert-butoxycarbonyl group.

< ingredient (B) >

The component (B) contained in the liquid crystal aligning agent of the present invention is a compound having 2 or more structures represented by the following formula (2) and having a molecular weight of 2500 or less.

In the above formula (2), R¹Represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.

R²And R³Each independently represents a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or³-CH₂-O-R¹¹(R¹¹Represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms ″)³"represents and R²And R³The linkage of the bonded carbon atoms), ", or¹"and²"denotes a bond to another atom.

As R¹And R¹¹Examples of the alkyl group having 1 to 3 carbon atoms include a methyl group, an ethyl group, an n-propyl group and an isopropyl group. Preferably a hydrogen atom or a methyl group, more preferably a hydrogen atom. In addition, R is¹And R¹¹May be the same or different from each other.

As R²And R³The alkyl group having 1 to 3 carbon atoms in (A) includes the above-mentioned R¹The groups exemplified in (1). Preferably a hydrogen atom³-CH₂-OH, or³-CH₂-OCH₃. In addition, R is²And R³May be the same or different from each other.

The group bonded to the nitrogen atom in the above formula (2) (hereinafter referred to as "R")⁴"), for example, a hydrogen atom, a 1-valent organic group, or a 2-valent organic group bonded to the carbonyl group in the above formula (2) and the nitrogen atom can be cited. In addition, R is⁴In the case of the 2-valent organic group, a ring structure is formed together with the nitrogen atom and the carbonyl group in the formula (2).

The number of structures represented by the above formula (2) in the compound of component (B) of the present invention may be 2 or more, preferably 2 to 8, and more preferably 2 to 6. The compound (B) has a group ″)⁴-CH₂-O-R¹(“*⁴Watch (watch)Showing a bond to a carbon atom. R¹The number of "the same as" above "is preferably 2 or more, more preferably 3 to 8, and further preferably 3 to 6 per 1 molecule.

Preferable specific examples of the structure of the formula (2) include compounds represented by the following formulae (2-1) to (2-6).

In the above formulae (2-1) to (2-5) "+¹"represents a connecting bond. In the formula (2-5), R⁵Is an alkyl group having 1 to 3 carbon atoms. In the above formula (2-6) ")¹"and⁵"represents a connecting bond to a group which forms a ring together with the nitrogen atom and the carbonyl group in the above formula (2-6).

The molecular weight of the compound (B) is 2500 or less. From the viewpoint of good solubility in a solvent and good coatability of the liquid crystal aligning agent, the molecular weight is preferably 2000 or less, and more preferably 1200 or less.

Specific examples of the compound (B) include compounds represented by the following formulae.

The compounding ratio of the compound (B) is preferably 0.1 to 100 parts by weight with respect to 100 parts by weight of the total of the polymer components contained in the liquid crystal aligning agent. The lower limit of the more preferable blending ratio of the compound (B) is 1 part by weight or more, and more preferably 3 parts by weight or more, based on 100 parts by weight of the total of the polymer components contained in the liquid crystal aligning agent. The upper limit of the blending ratio is more preferably 50 parts by weight or less, and still more preferably 20 parts by weight or less. The compound (B) may be used alone in 1 kind or in combination of 2 or more kinds.

< polyimide precursor and polyimide >

The polyimide precursor contained in the liquid crystal aligning agent of the present invention is a polyimide precursor obtained by a reaction of a diamine component containing a diamine represented by the above formula (1) and a tetracarboxylic acid derivative component. Here, the polyimide precursor is polyamic acid or polyamic acid ester.

Examples of the tetracarboxylic acid derivative include acid dianhydride, dicarboxylic acid diester, and diester diacid 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 diacid dichloride.

The polyimide contained in the liquid crystal aligning agent of the present invention is a polyimide obtained by ring-closing these polyimide precursors, and is useful as a polymer for obtaining a liquid crystal alignment film.

The polyimide precursor contained in the liquid crystal aligning agent of the present invention is a polymer containing a structural unit represented by the following formula (4).

In the above formula (4), X₁Is a 4-valent organic radical derived from a tetracarboxylic acid derivative, Y₁Is a 2-valent organic radical derived from a diamine of the formula (1), R₄Is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. From the viewpoint of easiness of imidization by heating, R₄Preferably a hydrogen atom, a methyl group or an ethyl group.

In the diamine component for obtaining the polyimide precursor, the content ratio of the diamine represented by the formula (1) is not limited, and the effect of the present invention can be easily obtained when the content ratio is large. The ratio of the diamine represented by the above formula (1) is preferably 1 to 80 mol%, more preferably 5 to 60 mol%, and still more preferably 10 to 40 mol% based on 1 mol of the total diamine component.

X₁The organic group is not particularly limited as long as it is a 4-valent organic group. In the polyimide precursor, X₁More than 2 kinds may be mixed.

If X is shown₁Specific examples of the (B) include The following formulae (X1-1) to (X1-44). From the viewpoint of availability, the following formulae (X1-1) to (X1-14) are more preferable.

In the formulae (X1-1) to (X1-4), R₅～R₂₅Each 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, a 1-valent organic group having 1 to 6 carbon atoms containing a fluorine atom, or a phenyl group, and may be the same or different. From the viewpoint of liquid crystal alignment, R₅～R₂₅Preferably a hydrogen atom, a halogen atom, a methyl group, or an ethyl group, more preferably a hydrogen atom or a methyl group. Specific examples of the structure of the formula (X1-1) include structures represented by the following formulae (X1-1-1) to (X1-1-6). From the viewpoint of liquid crystal alignment properties and sensitivity to photoreaction, the following formula (X1-1-1) is particularly preferable.

The polyimide precursor of the present invention may further contain a structural unit represented by the following formula (5) in addition to the above formula (4) within a range in which the effects of the present invention are not impaired. When the liquid crystal aligning agent of the present invention contains a polyimide precursor other than the polyimide precursor containing the structural unit represented by the above formula (4), the liquid crystal aligning agent may be a polyimide precursor having a structural unit represented by the following formula (5).

In the above formula (5), R₄The same as defined in the above formula (4). X₂Is a 4-valent organic group, including preferred examples, with X in the above formula (4)₁The same definition is applied. However, when the liquid crystal aligning agent of the present invention contains a polyimide precursor containing a structural unit of the formula (5) in addition to a polyimide precursor containing a structural unit of the formula (4), the formula (X1-8) is particularly preferable from the viewpoint of the effect expression of the obtained liquid crystal alignment film. Z₁And Z₂Each independently represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms which may have a substituent, an alkenyl group having 2 to 10 carbon atoms or an alkynyl group having 2 to 10 carbon atoms.

Specific examples of the alkyl group having 1 to 10 carbon atoms include methyl group, ethyl group, propyl group, butyl group, tert-butyl group, hexyl group, octyl group, decyl group, cyclopentyl group, cyclohexyl group, dicyclohexyl group and the like.

The alkenyl group having 2 to 10 carbon atoms includes at least one CH present in the alkyl group₂-CH₂A group substituted with CH ═ CH. More specifically, vinyl, allyl, 1-propenyl, isopropenyl, 2-butenyl, 1, 3-butadienyl, 2-pentenyl, 2-hexenyl, cyclopropenyl, cyclopentenyl, cyclohexenyl and the like are exemplified.

Examples of the alkynyl group having 2 to 10 carbon atoms include at least one CH present in the above alkyl group₂-CH₂A group substituted with C ≡ C. More specifically, ethynyl, 1-propynyl, 2-propynyl and the like are exemplified.

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 may have a substituent in the range that the total number of carbon atoms including the substituent does not exceed 10, and further, a ring structure may be formed by the substituent. The term "ring structure formed by substituents" 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 mercapto 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 group, an amide group, an alkyl group, an alkenyl group, and an alkynyl group.

In the polyimide precursor, generally, when a bulky structure is introduced, reactivity of amino groups and liquid crystal alignment properties may be lowered, and therefore, Z is a number₁And Z₂More preferably a hydrogen atom or an alkyl group having 1 to 5 carbon atoms which may have a substituent, and particularly preferably a hydrogen atom, a methyl group or an ethyl group.

In the above formula (5), Y ₂The divalent organic group is derived from a diamine component other than the diamine component represented by the above formula (1), and the structure thereof is not particularly limited. If listed, Y₂Specific examples of the (C) compound include the following formulae (Y-1) to (Y-49) and the following formulae (Y-57) to (Y-114). Further, 2 or more kinds of diamine components may be mixed.

In the formula (Y-158), the formula (Y-162) to the formula (Y-165), n is an integer of 1 to 6.

Boc in the formula (Y-174), the formula (Y-175), the formula (Y-178) and the formula (Y-179) represents a tert-butoxycarbonyl group.

< method for producing Polyamic acid >

The polyamic acid as a polyimide precursor used in the liquid crystal aligning agent 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 tetracarboxylic dianhydride and diamine in the presence of an organic solvent.

The organic solvent is not particularly limited as long as the formed polyamic acid is dissolved, and specific examples thereof include N, N-dimethylformamide, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methylcaprolactam, dimethylsulfoxide, and γ -butyrolactone. When the polyimide precursor has high solubility, an organic solvent represented by methyl ethyl ketone, cyclohexanone, cyclopentanone, 4-hydroxy-4-methyl-2-pentanone, or the following formulae (D-1) to (D-3) may be used.

In the above formula (D-1), D¹Represents an alkyl group having 1 to 3 carbon atoms, wherein D is represented by the formula (D-2)²Represents an alkyl group having 1 to 3 carbon atoms, wherein in the formula (D-3), D is³Represents a carbon number of 1 &4 alkyl group.

They may be used alone or in admixture thereof. Further, the solvent which does not dissolve the polyamic acid when used alone may be mixed with the above solvent in a range where the produced polyamic acid is not precipitated. In addition, since the water content in the organic solvent causes the inhibition of the polymerization reaction and the hydrolysis of the formed polyamic acid, it is preferable to use an organic solvent which is dehydrated and dried as much as possible.

Examples of the method of mixing the diamine component and the tetracarboxylic dianhydride in the organic solvent include a method of adding the tetracarboxylic dianhydride directly or by dispersing or dissolving the tetracarboxylic dianhydride in the organic solvent by stirring a solution in which the diamine is dispersed or dissolved in the organic solvent; a method of adding a diamine to a solution in which a tetracarboxylic dianhydride is dispersed or dissolved in an organic solvent; a method of adding the tetracarboxylic dianhydride and the diamine to the organic solvent alternately or simultaneously, and any of them may be used.

The temperature for the synthesis of the polyamic acid may be any temperature from-20 ℃ to 150 ℃, but is preferably in the range from-5 ℃ to 100 ℃, more preferably from 0 ℃ to 80 ℃.

The reaction time may be arbitrarily selected in a range longer than the time for which the polymerization of the polyamic acid is stable, but is preferably 30 minutes to 24 hours, more preferably 1 hour to 12 hours.

The reaction may be carried out at any concentration, but if the concentration of the diamine component and the tetracarboxylic dianhydride in the raw materials is too low, it is difficult to obtain a polymer having a high molecular weight, and if the concentration is too high, the viscosity of the reaction solution is too high to uniformly stir, and therefore, the concentration is preferably 1 to 50% by mass, more preferably 5 to 20% by mass. The reaction may be carried out at a high concentration at the initial stage of the reaction 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. Similarly to the ordinary polycondensation reaction, the molecular weight of the polyamic acid produced increases as the molar ratio approaches 1.0.

The polyamic acid obtained as described above can be injected into a poor solvent while sufficiently stirring the reaction solution, whereby a polymer can be precipitated and recovered. Further, the polyamic acid is precipitated several times, washed with a poor solvent, and dried at room temperature or under heating to obtain a powder of a purified polyamic acid.

The poor solvent is not particularly limited, and examples thereof include water, methanol, ethanol, 2-propanol, hexane, butyl cellosolve, acetone, toluene, and the like, and water, methanol, ethanol, 2-propanol, and the like are preferable.

< production of Polyamic acid ester >

The polyamic acid ester as a polyimide precursor of the present invention can be produced by the production method of [1], [2] or [3] shown below.

[1] When produced from polyamic acid

The polyamic acid ester can be produced by esterifying the polyamic acid produced as described above.

Specifically, the polyamic acid can be produced by reacting a polyamic acid with an esterifying agent in the presence of an organic solvent at-20 to 150 ℃ and preferably 0 to 50 ℃ for 30 minutes to 24 hours, and preferably 1 to 4 hours.

The esterification agent is preferably an esterification agent which can be easily removed by purification, and examples thereof include N, N-dimethylformamide dimethyl acetal, N-dimethylformamide diethyl acetal, N-dimethylformamide dipropyl acetal, N-dimethylformamide dineopentylbutyl acetal, N-dimethylformamide di-tert-butyl acetal, 1-methyl-3-p-tolyltriazene, 1-ethyl-3-p-tolyltriazene, 1-propyl-3-p-tolyltriazene, and 4- (4, 6-dimethoxy-1, 3, 5-triazin-2-yl) -4-methylmorpholinium chloride. The amount of the esterifying agent to be added is preferably 2 to 6 molar equivalents based on 1 mole of the repeating unit of the polyamic acid.

Examples of the organic solvent include N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, γ -butyrolactone, N-dimethylformamide, N-dimethylacetamide, dimethylsulfoxide, and 1, 3-dimethyl-imidazolidinone. When the polyimide precursor has high solubility in a solvent, methyl ethyl ketone, cyclohexanone, cyclopentanone, 4-hydroxy-4-methyl-2-pentanone, or solvents represented by the formulae (D-1) to (D-3) may be used.

The solvents may be used alone or in admixture. Further, even in the case of a solvent which does not dissolve the polyimide precursor, the solvent may be mixed with the polyimide precursor in such a range that the produced polyimide precursor is not precipitated. In addition, the water content in the solvent is a factor of suppressing the polymerization reaction and further hydrolyzing the polyimide precursor produced, and therefore, it is preferable to use a dehydrated solvent as the solvent.

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, and 1 or 2 or more kinds thereof may be used in combination. The concentration during production is preferably 1 to 30% by mass, more preferably 5 to 20% by mass, from the viewpoint of preventing precipitation of a polymer and facilitating production of a high molecular weight material.

[2] When produced by the reaction of a tetracarboxylic acid diester diacid chloride with a diamine

The polyamic acid ester can be produced from a tetracarboxylic acid diester diacid chloride and a diamine component containing the diamine of the present invention.

Specifically, the tetracarboxylic acid diester can be produced by reacting a tetracarboxylic acid diester diacid chloride with a diamine in the presence of a base and an organic solvent at-20 to 150 ℃, preferably 0 to 50 ℃ for 30 minutes to 24 hours, preferably 1 hour to 4 hours.

As the base, pyridine, triethylamine, 4-dimethylaminopyridine and the like can be used, but pyridine is preferable for mildly performing the reaction. The amount of the base to be added is preferably 2 to 4 times by mol, more preferably 2 to 3 times by mol, based on the tetracarboxylic acid diester diacid chloride, from the viewpoint of ease of removal and availability of a high molecular weight product.

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 1 kind or 2 or more kinds mixed may be used.

The polymer concentration during production is preferably 1 to 30% by mass, more preferably 5 to 20% by mass, from the viewpoint that polymer precipitation is not likely to occur and a high molecular weight product is easily obtained.

In order to prevent hydrolysis of the tetracarboxylic acid diester diacid chloride, the solvent used in the production of the polyamic acid ester is preferably dehydrated as much as possible, and it is preferable to prevent the mixing of external air in a nitrogen atmosphere.

[3] When produced from a tetracarboxylic acid diester and a diamine

The polyamic acid ester can be produced by polycondensing a tetracarboxylic acid diester and a diamine component containing the diamine of the present invention.

Specifically, the diamine can be produced by reacting a tetracarboxylic acid diester with a diamine in the presence of a condensing agent, a base, and an organic solvent at 0 to 150 ℃, preferably 0 to 100 ℃ for 30 minutes to 24 hours, preferably 3 to 15 hours.

As the condensing agent, triphenyl phosphite, dicyclohexylcarbodiimide, 1-ethyl-3- (3-dimethylaminopropyl) carbodiimide hydrochloride, N, N ' -carbonyldiimidazole, dimethoxy-1, 3, 5-triazinylmethyl morpholinium, 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-thio-3-benzoxazolyl) phosphonate and the like can be used. The amount of the condensing agent to be added is preferably 2 to 3 times by mol, more preferably 2 to 2.5 times by mol, based on the tetracarboxylic acid diester.

As the base, tertiary amines such as pyridine and triethylamine can be used. The amount of the base to be added is preferably 2 to 4 times by mol, more preferably 2.5 to 3.5 times by mol, based on the diamine component, from the viewpoint of ease of removal and availability of a high molecular weight product.

In addition, in the above reaction, the reaction is efficiently carried out by adding a lewis acid as an additive. The lewis acid is preferably a lithium halide such as lithium chloride or lithium bromide. The amount of the lewis acid to be added is preferably 0 to 1.0 mol per mol of the diamine component, and more preferably 0 to 0.7 mol per mol of the diamine component.

Among the above 3 methods for producing polyamic acid esters, the above 1 or 2 is particularly preferred for obtaining a polyamic acid ester having a high molecular weight.

The solution of the polyamic acid ester obtained as described above is injected into a poor solvent while sufficiently stirring, whereby a polymer can be precipitated. The polyamic acid ester is precipitated several times, washed with a poor solvent, and dried at room temperature or under 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, toluene, and the like.

< 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 depending on 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, it is preferable to heat a solution of the polyimide precursor to 100 to 400 ℃, preferably 120 to 250 ℃, and to remove water or alcohol produced by the imidization reaction from the system.

The catalytic imidization of the polyimide precursor can be carried out by adding a basic catalyst and an acid anhydride to a solution of polyamic acid and stirring at-20 to 250 ℃, preferably 0 to 180 ℃. The amount of the basic catalyst is 0.5 to 30 times, preferably 2 to 20 times, the amount of the acid anhydride is 1 to 50 times, preferably 3 to 30 times, the amount of the acid amide group.

Examples of the basic catalyst include pyridine, triethylamine, trimethylamine, tributylamine, and trioctylamine, and among them, pyridine is preferable because it has a suitable basicity for proceeding the reaction.

Examples of the acid anhydride include acetic anhydride, trimellitic anhydride, and pyromellitic anhydride, and among these, acetic anhydride is preferable because purification after completion of the reaction is easy. The imidization rate by the catalyst imidization can be controlled by adjusting the amount of the catalyst, the reaction temperature, and the reaction time.

When the polymer component is recovered from the polyimide reaction solution, the reaction solution may be put into a poor solvent to precipitate. Examples of the poor solvent used for precipitation include methanol, acetone, hexane, butyl cellosolve, heptane, methyl ethyl ketone, methyl isobutyl ketone, ethanol, toluene, benzene, and water. The polymer obtained by precipitating the polymer by adding the poor solvent is preferably filtered and recovered, and then dried at normal temperature or under reduced pressure or by heating.

< liquid Crystal Aligning agent >

The liquid crystal aligning agent is a coating liquid for producing a liquid crystal alignment film, and is a composition containing, as its main components, a resin component for forming a resin coating film and an organic solvent for dissolving the resin component. The liquid crystal aligning agent of the present invention uses, as a resin component, at least one polymer selected from the group consisting of the polyimide precursor and a polyimide obtained by ring-closing the polyimide precursor.

The concentration of the polymer in the liquid crystal aligning agent can be appropriately changed according to the setting of the thickness of the coating film to be formed. From the viewpoint of forming a uniform and defect-free coating film, it is preferably 1% by mass or more, and from the viewpoint of storage stability of the solution, it is preferably 10% by mass or less. The polymer concentration is particularly preferably 2 to 8% by mass.

The resin component in the liquid crystal aligning agent may be all the polymers of the present invention, or may be mixed with other polymers than the polymers of the present invention. Examples of the other polymer include polyimide precursors and polyimides obtained by using a diamine other than the diamine represented by the formula (1) as a 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-diethylformamide, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-methylcaprolactam, 2-pyrrolidone, N-vinyl-2-pyrrolidone, dimethyl sulfoxide, dimethyl sulfone, γ -butyrolactone, 1, 3-dimethyl-imidazolidinone, and 3-methoxy-N, N-dimethylpropionamide. These can be used in 1 or more than 2 kinds. The organic solvent may be mixed with the solvent in a range where the polymer does not precipitate even if the solvent is used alone, and the polymer component cannot be uniformly dissolved.

The liquid crystal aligning agent may contain a solvent for improving the uniformity of a coating film when the liquid crystal aligning agent is applied to a substrate, in addition to an organic solvent for dissolving the polymer component. As the solvent, a solvent having a lower surface tension than the organic solvent is usually 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, 1-butoxy-2-propanol, 2-butoxy-1-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 monomethyl ether, dipropylene glycol dimethyl ether, diacetone alcohol, diethylene glycol diethyl ether, 2, 6-dimethyl-4-heptanol, methyl glycol, ethyl carbitol, butyl carbitol acetate, butyl glycol acetate, propylene glycol diacetate, dimethyl glycol, ethyl carbitol, ethyl glycol acetate, ethyl carbitol acetate, ethyl carbitol, ethyl acetate, ethyl carbitol, ethyl acetate, ethyl, Diisobutyl ketone, 4-methoxy-4-methyl-2-pentanone, 4-hydroxy-2-butanone and 2-methyl-2-hexanol, 2- (2-ethoxypropoxy) propanol, methyl lactate, ethyl lactate, n-propyl lactate, n-butyl lactate, isoamyl lactate, and the like. These solvents may be used in combination of 2 or more.

The solvent is a poor solvent having low solubility in the resin. These solvents are preferably 5 to 60% by mass, more preferably 10 to 50% by mass of the organic solvent contained in the liquid crystal aligning agent.

In addition to the above, a polymer other than the polymer of the present invention, a dielectric or conductive material for changing electric characteristics such as dielectric constant, conductivity, and the like of the liquid crystal alignment film, a silane coupling agent for improving adhesion between the liquid crystal alignment film and a substrate, a crosslinkable compound for improving hardness and density of the film when the liquid crystal alignment film is formed, an imidization accelerator for effectively imidizing a polyimide precursor when the film is baked, and the like may be added to the liquid crystal alignment agent within a range in which the effects of the present invention are not impaired.

When a crosslinkable compound such as a functional silane-containing compound or an epoxy-containing compound is contained, the amount thereof is preferably 0.1 to 30 parts by mass, more preferably 1 to 20 parts by mass, and particularly preferably 1 to 10 parts by mass, per 100 parts by mass of the resin component.

< method for producing liquid Crystal alignment film >

The liquid crystal alignment film is obtained by applying the liquid crystal alignment agent to a substrate, drying the applied liquid crystal alignment agent, and baking the dried liquid crystal alignment film.

The substrate to which the liquid crystal aligning agent is applied is not particularly limited as long as it is a substrate having high transparency, and a plastic substrate such as a glass substrate, a silicon nitride substrate, an acrylic substrate, or a polycarbonate substrate can be used. In particular, a substrate on which an ITO electrode or the like for driving a liquid crystal is formed is preferably used from the viewpoint of simplification of the process.

In the case of the reflective liquid crystal display element, an opaque substrate such as a silicon wafer may be used as long as it is a single-sided substrate, and in this case, a material that reflects light such as aluminum may be used as the electrode.

Examples of the method for applying the liquid crystal aligning agent include spin coating, printing, and ink jet. Further, as a method of using the coating liquid, there are dipping, a roll coater, a slit coater, a spin coater, and the like, and they can be used according to the purpose.

The drying and firing steps after the application of the liquid crystal aligning agent may be performed at any temperature and for any time. Usually, in order to sufficiently remove the organic solvent contained, the organic solvent is dried at 50 to 120 ℃ and preferably 50 to 80 ℃ for 1 to 10 minutes, preferably 3 to 5 minutes, and then fired at 150 to 300 ℃ and preferably 200 to 240 ℃ for 5 to 120 minutes, preferably 10 to 40 minutes.

The thickness of the coating film after firing is not particularly limited, and is 5nm to 300nm, preferably 10nm to 200nm, since the reliability of the liquid crystal display element may be lowered if the thickness is too small.

Examples of a method for performing alignment treatment on the obtained liquid crystal alignment film include a rubbing method and a photo-alignment treatment method. The rubbing treatment may be rayon cloth, nylon cloth, cotton cloth, or the like. Since it is difficult to obtain a uniform alignment state by rubbing treatment, a liquid crystal alignment film for vertical alignment may be used as a liquid crystal aligning agent for vertical alignment without rubbing.

Specific examples of the photo-alignment treatment method include a method of irradiating the surface of the coating film with radiation polarized in a fixed direction, and if necessary, further performing a heat treatment at a temperature of 150 to 250 ℃ to impart liquid crystal alignment ability. As the radiation rays, ultraviolet rays and visible rays having a wavelength of 100nm to 800nm can be used. Among them, ultraviolet rays having a wavelength of 100nm to 400nm are preferable, and ultraviolet rays having a wavelength of 200nm to 400nm are particularly preferable.

In order to improve the liquid crystal alignment properties, the coated substrate may be irradiated with radiation while being heated at 50 to 250 ℃.

The irradiation dose of the radiation is preferably 1mJ/cm²～10000mJ/cm²Particularly preferably 100mJ/cm²～5000mJ/cm². The liquid crystal alignment film manufactured as described above can stably align liquid crystal molecules in a fixed direction.

The film irradiated with polarized radiation may be subsequently subjected to a contact treatment 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 dissolves a decomposition product generated by light irradiation. Specific examples thereof include water, methanol, ethanol, 2-propanol, acetone, methyl ethyl ketone, 1-methoxy-2-propanol acetate, butyl cellosolve, ethyl lactate, methyl lactate, diacetone alcohol, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, propyl acetate, butyl acetate, and cyclohexyl acetate. These solvents may be used in combination of 2 or more.

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 1-methoxy-2-propanol or ethyl lactate.

In the present invention, the contact treatment of the film irradiated with polarized radiation and the solution containing an organic solvent is preferably performed by a treatment such that the film is sufficiently contacted with a liquid, such as a dipping treatment or a spraying (spray) treatment. Among these methods, a method of immersing the film in a solution containing an organic solvent is preferable, and the method is preferably performed for 10 seconds to 1 hour, and more preferably for 1 minute to 30 minutes. The contact treatment may be carried out at normal temperature or under heating, but is preferably carried out at 10 to 80 ℃ and more preferably at 20 to 50 ℃. Further, if necessary, means for improving the contact such as ultrasonic waves may be applied.

After the contact treatment, either or both of rinsing (washing) and drying may be performed using a low boiling point solvent such as water, methanol, ethanol, 2-propanol, acetone, and methyl ethyl ketone in order to remove the organic solvent in the solution used.

Further, the film subjected to the contact treatment with the solvent may be heated at 150 ℃ or higher for drying the solvent and reorienting molecular chains in the film.

The heating temperature is preferably 150 to 300 ℃. While the higher the temperature, the more the reorientation of the molecular chain is promoted, the higher the temperature, the decomposition of the molecular chain may be accompanied. Therefore, the heating temperature is more preferably 180 to 250 ℃ and particularly preferably 200 to 230 ℃.

If the time for heating is too short, the effect of the present invention may not be obtained, and if it is too long, the molecular chain may be decomposed, and therefore, it is preferably 10 seconds to 30 minutes, more preferably 1 minute to 10 minutes.

< liquid crystal display element >

The liquid crystal display element is obtained by forming a liquid crystal display element using a liquid crystal cell produced by a known method after obtaining a substrate with a liquid crystal alignment film obtained from the liquid crystal alignment agent of the present invention.

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 the liquid crystal display element may be an active matrix liquid crystal display element in which a switching element such as a Thin Film Transistor (TFT) is provided in each pixel portion constituting image display.

First, a transparent glass substrate is prepared, a common electrode is provided on one substrate, and segment electrodes are provided on the other substrate. These electrodes may be formed as ITO electrodes, for example, and patterned so that a desired image representation can be performed. Then, an insulating film is provided on each substrate so as to cover the common electrode and the segment electrode. The insulating film may be formed of SiO formed by a sol-gel method₂-TiO₂The film formed.

Next, the liquid crystal alignment film of the present invention is formed on each substrate. Then, the alignment films are opposed to each other, and one substrate is stacked on the other substrate, and the periphery is bonded with a sealing material. In the sealing material, a spacer is usually mixed in order to control the substrate gap. Further, it is preferable that spacers for controlling the substrate gap are scattered also in the surface portion where the sealing material is not provided. An opening capable of being filled with liquid crystal from the outside is provided in a part of the sealing material.

Next, a liquid crystal material was injected into the space surrounded by the 2 substrates and the sealing material through the opening provided in the sealing material. The opening is then sealed with an adhesive. The injection may be performed by a vacuum injection method or a method using a capillary phenomenon in the atmosphere. Further, the substrate may be filled with a liquid crystal by drawing a sealing material on the substrate, dropping the liquid crystal, and bonding under reduced pressure.

As the liquid crystal material, any of a positive type liquid crystal material and a negative type liquid crystal material can be used. In particular, even when a negative liquid crystal material having a lower voltage holding ratio than a positive liquid crystal material is used, the liquid crystal alignment film of the present invention has excellent image sticking characteristics.

Then, a polarizing plate is disposed. Specifically, a pair of polarizing plates was attached to the surfaces of the 2 substrates opposite to the liquid crystal layer. Through the above steps, the liquid crystal display element of the present invention is obtained. Since the liquid crystal alignment film obtained by the method for producing a liquid crystal alignment film of the present invention is used as a liquid crystal alignment film, the liquid crystal display element has excellent afterimage characteristics and is suitable for high-definition multifunctional mobile phones (smart phones), tablet personal computers, liquid crystal televisions, and the like.

Examples

The present invention will be described more specifically with reference to the following examples. However, the present invention is not limited to or interpreted by these examples. The abbreviations of the compounds used hereinafter and the methods for measuring the respective characteristics are as follows.

< abbreviation of Compound >

In the following formulas DA-5 and DA-6, "Boc" is a tert-butoxycarbonyl group.

< abbreviation of Compound >

DA-7: 1, 3-bis (4-aminophenylethyl) urea

DA-8: 4- (2-methylaminoethyl) aniline

NMP: n-methyl-2-pyrrolidone

BCS: butyl cellosolve

GBL: gamma-butyrolactone

< viscosity >

In the synthesis example, the viscosity of the polymer solution was measured at a sample volume of 1.1mL and a temperature of 25 ℃ using an E-type viscometer TVE-22H (manufactured by Toyobo Co., Ltd.) and a cone rotor TE-1(1 ℃ 34', R24).

< fabrication of liquid Crystal display element >

First, a substrate with electrodes is prepared. The substrate was a glass substrate having a size of 30mm × 35mm and a thickness of 0.7 mm. An IZO electrode having a solid pattern constituting a counter electrode is formed as a 1 st layer on a substrate. On the counter electrode of the 1 st layer, a SiN (silicon nitride) film formed by a CVD method is formed as a 2 nd layer. The SiN film of the 2 nd layer has a film thickness of 500nm and functions as an interlayer insulating film. On the SiN film of the 2 nd layer, comb-shaped pixel electrodes formed by patterning an IZO film are arranged as a 3 rd layer, and two kinds of pixels, i.e., the 1 st pixel and the 2 nd pixel, are formed. The size of each pixel was 10mm in length and 5mm in width. At this time, the counter electrode of the 1 st layer and the pixel electrode of the 3 rd layer are electrically insulated by the SiN film of the 2 nd layer.

The pixel electrode of the layer 3 has a comb-tooth shape in which a plurality of く -shaped electrode elements each having a curved central portion are arranged. The width of each electrode element in the width direction was 3 μm, and the interval between the electrode elements was 6 μm. Since the pixel electrode forming each pixel is formed by arranging a plurality of く -shaped electrode elements each having a bent central portion, the shape of each pixel is not rectangular, and like the electrode element, the pixel electrode has a shape similar to く -shaped electrode element having a zigzag bent central portion. Each pixel is divided into an upper 1 st region and a lower 2 nd region by a curved portion at the center as a boundary.

When the 1 st region and the 2 nd region of each pixel are compared, the formation directions of the electrode elements constituting the pixel electrodes are different. That is, when the rubbing direction of the liquid crystal alignment film described later is set as a reference, the electrode element of the pixel electrode is formed to have an angle of +10 ° (clockwise rotation) in the 1 st region of the pixel, and the electrode element of the pixel electrode is formed to have an angle of-10 ° (counterclockwise rotation) in the 2 nd region of the pixel. That is, the 1 st region and the 2 nd region of each pixel are configured such that the directions of the rotational operation (in-plane switching) of the liquid crystal in the substrate plane induced by the voltage application between the pixel electrode and the counter electrode are opposite to each other.

The obtained liquid crystal aligning agent was filtered through a 1.0 μm filter, and then spin-coated on the prepared substrate with electrodes and a glass substrate as a counter substrate, on the back of which an ITO film was formed and which had a columnar spacer with a height of 4 μm. Then, the film was dried on a hot plate at 80 ℃ for 5 minutes, and then baked at 230 ℃ for 20 minutes to form a coating film having a film thickness of 60nm, thereby obtaining a polyimide film on each substrate. The polyimide film was rubbed with rayon cloth in a predetermined rubbing direction (roll diameter: 120mm, rotation speed: 500rpm, moving speed: 30 mm/sec, and tucking length: 0.3mm), then subjected to ultrasonic irradiation in pure water for 1 minute, and dried at 80 ℃ for 10 minutes.

Then, the 2 kinds of substrates with the liquid crystal alignment films were combined so that the rubbing directions thereof were antiparallel to each other, and the liquid crystal injection port was left and the periphery was sealed to prepare an empty cell having a cell gap of 3.8 μm. After vacuum-injecting liquid crystal (MLC-2041, manufactured by Merck Ltd.) into the empty cell at normal temperature, the injection port was sealed to form an antiparallel aligned liquid crystal cell. The resulting liquid crystal cell constitutes an FFS (boundary electric field switching) mode liquid crystal display element. The resulting liquid crystal cell was then heated at 120 ℃ for 1 hour, and placed evening-out for each evaluation.

< evaluation of relaxation Property of Charge accumulation >

The afterimage was evaluated using the following optical system and the like. The fabricated liquid crystal cell was placed between 2 polarizing plates arranged so that the polarizing axes were orthogonal to each other, and the arrangement angle of the liquid crystal cell was adjusted so that the brightness of transmitted light was minimized by turning on the LED backlight in a state where no voltage was applied.

Then, a V-T curve (voltage-transmittance curve) was measured while applying an ac voltage having a frequency of 30Hz to the liquid crystal cell, and an ac voltage having a relative transmittance of 23% was calculated as a driving voltage.

In the evaluation of the image sticking, the liquid crystal cell was driven by applying an alternating voltage having a frequency of 30Hz and a relative transmittance of 23%, and a direct voltage of 1V was applied for 40 minutes. Then, the dc voltage was set to 0V, and the driving was stopped for 15 minutes in this state.

In the evaluation, when the relative transmittance decreased to 25% or less from the time when the application of the dc voltage was started until 45 minutes elapsed, the evaluation was defined as "good". When it took 45 minutes or more until the relative transmittance decreased to 25% or less, the evaluation was made by defining it as "poor".

The evaluation of the residual image according to the above method was performed under a temperature condition in which the temperature of the liquid crystal cell was 23 ℃.

< evaluation of stability of liquid Crystal alignment >

Using this liquid crystal cell, an alternating voltage of 10VPP was applied at a frequency of 30Hz for 168 hours in a constant temperature environment of 60 ℃. Then, a short circuit was formed between the pixel electrode and the counter electrode of the liquid crystal cell, and the cell was left at room temperature for one day.

After the placement, the liquid crystal cell was placed between 2 polarizing plates arranged so that the polarizing axes were orthogonal, and the backlight was turned on in a state where no voltage was applied, and the arrangement angle of the liquid crystal cell was adjusted so that the luminance of transmitted light was minimum. Then, the rotation angle when the liquid crystal cell is rotated from the 2 nd area darkest angle of the 1 st pixel to the 1 st area darkest angle is calculated as an angle Δ. Similarly, for the 2 nd pixel, the 2 nd region and the 1 st region are compared, and the same angle Δ is calculated. Next, the average value of the angle Δ values of the 1 st pixel and the 2 nd pixel is calculated as the angle Δ of the liquid crystal cell. When the value of the angle Δ of the liquid crystal cell exceeds 0.1 degree, the evaluation was performed by defining the cell as "defective". When the value of the angle Δ of the liquid crystal cell was not more than 0.1 degrees, the evaluation was defined as "good".

< evaluation of BL resistance >

The fabricated liquid crystal cell was aged for 1 week above BL of 2000 nit. After aging, a voltage of 1V was applied to the cell at a temperature of 60 ℃ for 60. mu.sec, and the voltage after 100msec was measured to evaluate the voltage holding ratio.

In this case, the voltage holding ratio was defined as "good" when it was maintained at 80% or more, and was defined as "bad" when it was less than 80%.

< evaluation of Friction resistance >

The liquid crystal alignment agent was coated on an ITO substrate, and after pre-drying, the substrate was fired in an IR oven at 230 ℃. This liquid crystal alignment film was rubbed with rayon cloth (roll rotation speed: 1000rpm, stage moving speed: 20 mm/sec, plunge length: 0.4 mm). When the substrate was observed with a microscope, the film surface was evaluated as "good" when no streaks were observed due to rubbing, and as "bad" when streaks were observed.

< Synthesis example >

(Synthesis example 1)

DA-334.36 g (0.12 mol) was put into a 500mL flask equipped with a stirrer and a nitrogen inlet, and then 335.12g of NMP was added thereto, followed by stirring and dissolving. This solution was stirred with water, and CA-122.77 g (0.10 mol) was added thereto, NMP83.80g was further added thereto, and the mixture was stirred at 50 ℃ for 12 hours to obtain a polyamic acid solution (PAA-1).

(Synthesis example 2)

A500 mL flask equipped with a stirrer and a nitrogen inlet was charged with DA-325.20 g (0.088 mol) and DA-68.77 g (0.022 mol), and then 333.97g of NMP was added thereto, followed by stirring and dissolving. This solution was stirred with water, and CA-122.96 g (0.11 mol) was added thereto, and NMP 326g was further added thereto, and stirred at 50 ℃ for 12 hours to obtain a polyamic acid solution (PAA-2).

(Synthesis example 3)

A500 mL flask equipped with a stirrer and a nitrogen inlet was charged with DA-325.20 g (0.088 mol) and DA-58.72 g (0.022 mol), and then 334.28g of NMP was added thereto and dissolved by stirring. This solution was stirred with water, and CA-123.06 g (0.11 mol) was added thereto, NMP83.57g was further added thereto, and stirred at 50 ℃ for 12 hours to obtain a polyamic acid solution (PAA-3).

(Synthesis example 4)

After DA-419.13 g (0.096 mol) was put into a 500mL flask equipped with a stirrer and a nitrogen inlet, 232.72g of a solvent (NMP: GBL 50 wt%: 50 wt%) was added thereto, and the mixture was stirred and dissolved. This solution was stirred with water, while adding CA-214.12 g (0.072 mol), 84.63g of a solvent (NMP: GBL 50 wt%: 50 wt%), and then stirred for 2 hours. Then, 14.76 g (0.024 mol) of DA was added, and 42.31g of NMPl was added, followed by stirring and dissolving. CA-39.00 g (0.03 mol) was added again while stirring with water cooling, and 326g of a solvent (NMP: GBL 50 wt%: 50 wt%) was further added thereto, and after stirring for 2 hours, a polyamic acid solution (PAA-4) was obtained.

Synthesis example 5

A500 mL flask equipped with a stirrer and a nitrogen inlet was charged with DA-423.91 g (0.12 mol) and DA-15.95 g (0.03 mol), and then NMP 255.76g was added thereto, followed by stirring and dissolving. This solution was stirred with water, and after adding 26.47 g (0.033 mol) of CA-and further 73.01g of NMP, the mixture was stirred for 2 hours. Then, CA-428.15 g (0.11 mol) was added, and NMP36.54g was added thereto, followed by stirring at 50 ℃ for 12 hours to obtain a polyamic acid solution (PAA-5).

(Synthesis example 6)

A500 mL flask equipped with a stirrer and a nitrogen inlet was charged with DA-423.91 g (0.12 mol) and DA-24.56 g (0.03 mol), and then 241.76g of NMP was added thereto, followed by stirring and dissolving. This solution was stirred with water, and after adding CA-213.71 g (0.070 mol) and NMP69.07g, the mixture was stirred for 2 hours. CA-418.77 g (0.075 mol) was added, NMP34.54g was added, and the mixture was stirred at 50 ℃ for 12 hours to obtain a polyamic acid solution (PAA-6).

(Synthesis example 7)

A500 mL flask equipped with a stirrer and a nitrogen inlet was charged with DA-428.69 g (0.144 mol) and DA-17.14 g (0.036 mol), and then 296.56g of NMP was added thereto, followed by stirring and dissolving. The solution was stirred with water, CA-216.41 g (0.084 mol) was added thereto, and nmp84.73g was further added thereto, followed by stirring for 2 hours. CA-422.52 g (0.09 mol) was added, NMP42.37g was added, and the mixture was stirred at 50 ℃ for 12 hours to obtain a polyamic acid solution (PAA-7).

(Synthesis example 8)

A500 mL flask equipped with a stirrer and a nitrogen inlet was charged with DA-518.98 g (0.048 mol) and DA-714.28 g (0.048 mol), and then 312.67g of NMP was added thereto and dissolved by stirring. This solution was stirred with water, and CA-120.04 g (0.092 mol) was added thereto, and NMP78.17g was further added thereto, followed by stirring at 50 ℃ for 12 hours to obtain a polyamic acid solution (PAA-8).

(Synthesis example 9)

A500 mL flask equipped with a stirrer and a nitrogen inlet was charged with DA-726.85 g (0.09 mol) and DA-89.01 g (0.06 mol), and then 289.28g of NMP was added thereto and stirred to dissolve them. This solution was stirred with water, and CA-227.94 g (0.14 mol) was added thereto, and NMP72.32g was further added thereto, followed by stirring for 2 hours to obtain a polyamic acid solution (PAA-9).

Comparative example 1

In a 20ml sample tube containing a stirrer, 11.51 g of PAA-46.99 g of PAA, 1.51g of NMP, 3.13g of GBL3, 6.00g of BCS and 0.86g of GBL solution containing 11 wt% of AD were taken, and the mixture was stirred with a magnetic stirrer for 30 minutes to obtain a liquid crystal aligning agent (A-1).

Comparative example 2

In a 20ml sample tube containing a stirrer, 11.33 g of PAA-54.27 g and 0.64g of NMP4.40g, GBL5.36g, BCS4.00g and GBL solution containing 11 wt% of AD were taken, and the mixture was stirred with a magnetic stirrer for 30 minutes to obtain a liquid crystal aligning agent (A-2).

Comparative example 3

A20 ml sample tube containing a stirrer was charged with PAA-21.33 g and PAA-64.27 g, and then charged with NMP4.40g, GBL5.36g, BCS4.00g, and 0.64g of GBL solution containing AD-21 wt%, and stirred with a magnetic stirrer for 30 minutes to obtain a liquid crystal aligning agent (A-3).

Comparative example 4

A20 ml sample tube containing a stirrer was charged with PAA-82.00 g and PAA-96.40 g, then NMP1.60g, GBL5.04g, BCS4.00g, and 0.96g of GBL solution containing AD-21 wt% were added, and the mixture was stirred with a magnetic stirrer for 30 minutes to obtain a liquid crystal alignment agent (A-4).

(example 1)

A20 ml sample tube containing a stirrer was charged with PAA-31.33 g and PAA-64.27 g, NMP4.40g, GBL5.36g, BCS4.00g, and 0.64g of GBL solution containing AD-21 wt% and stirred with a magnetic stirrer for 30 minutes to obtain a liquid crystal aligning agent (B-1).

(example 2)

A20 ml sample tube containing a stirrer was charged with PAA-31.33 g and PAA-64.27 g, NMP4.16g, GBL5.36g, BCS4.00g, 0.64g of GBL solution containing AD-21 wt% and 0.24g of NMP solution containing AD-310 wt% were added, and the mixture was stirred with a magnetic stirrer for 30 minutes to obtain a liquid crystal aligning agent (B-2).

(example 3)

A20 ml sample tube containing a stirrer was charged with PAA-31.33 g and PAA-74.27 g, NMP4.40g, GBL5.36g, BCS4.00g, and 0.64g of GBL solution containing AD-21 wt% and stirred with a magnetic stirrer for 30 minutes to obtain a liquid crystal aligning agent (B-3).

(example 4)

A20 ml sample tube containing a stirrer was charged with PAA-31.33 g and PAA-74.27 g, NMP4.16g, GBL5.36g, BCS4.00g, 0.64g of GBL solution containing AD-21 wt% and 0.24g of NMP solution containing AD-310 wt% were added, and the mixture was stirred with a magnetic stirrer for 30 minutes to obtain a liquid crystal aligning agent (B-4). The liquid crystal aligning agent obtained above was used to evaluate BL resistance, relaxation properties of charge accumulation, stability of liquid crystal alignment, and rubbing resistance. The results are shown in table 1 below.

[ Table 1]

As described above, the liquid crystal alignment film of the present invention showed good results in any of the evaluation of the rubbing resistance, the evaluation of the BL resistance, the evaluation of the stability of the liquid crystal alignment, and the evaluation of the residual image disappearance time.

Claims

1. A liquid crystal aligning agent comprising the following components (A) and (B),

(A) the components: at least 1 polymer 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,

in the formula (1), R₁Represents hydrogen or a 1-valent organic group, Q₁Represents an alkylene group having 1 to 5 carbon atoms, Cy represents a group containing 2-valent radical of an aliphatic heterocycle of azetidine, pyrrolidine, piperidine or hexamethyleneimine, optionally having substituents bonded to their ring moieties, R₂And R₃Each independently is a 1-valent organic group, q and R are each independently an integer of 0 to 4, wherein when the sum of q and R is 2 or more, a plurality of R' s₂And R₃Has the above-mentioned definition, and can be used for making various foods,

(B) the components: a compound having 2 or more partial structures represented by the following formula (2) and having a molecular weight of 2500 or less,

in the formula (2), R¹R represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms²And R³Each independently represents a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or³-CH₂-O-R¹¹Wherein R is¹¹Represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms ″)³"represents and R²And R³A linkage of the bonded carbon atoms, "+"¹"and")²"denotes a bond to another atom.

2. The liquid crystal aligning agent according to claim 1, wherein the diamine of formula (1) is represented by formula (3),

in the formula (3), R₁Is a hydrogen atom, a methyl group or a tert-butoxycarbonyl group, R₂And R₃Each independently being a hydrogen atom or a methyl group, Q₁Is a C1-5 linear alkylene group.

3. The liquid crystal aligning agent according to claim 1 or 2, wherein the content ratio of the diamine represented by the formula (1) is 1 to 80 mol% based on 1 mol of the total diamine components.

4. The liquid crystal aligning agent according to claim 1 or 2, wherein the compound of the component (B) is at least one compound selected from the following formulae,

5. the liquid crystal aligning agent according to claim 1 or 2, further comprising a polyimide precursor containing a structural unit of the following formula (5) as the component (C),

in formula (5), X₂Is a 4-valent organic radical derived from a tetracarboxylic acid derivative, Y₂Is a 2-valent organic radical derived from a diamine, R₄Is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, Z₁And Z₂Each independently represents 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.

6. The liquid crystal aligning agent according to claim 5, which comprises a compound containing X in the formula (5)₂A polyimide precursor which is a structural unit of the following structure,

7. a liquid crystal alignment film obtained from the liquid crystal aligning agent according to any one of claims 1 to 6.

8. A liquid crystal display element comprising the liquid crystal alignment film according to claim 7.