CN111263913B

CN111263913B - Liquid crystal aligning agent, liquid crystal alignment film, and liquid crystal display element

Info

Publication number: CN111263913B
Application number: CN201880069277.6A
Authority: CN
Inventors: 山极大辉; 矢田研造; 张元聪
Original assignee: Nissan Chemical Corp
Current assignee: Nissan Chemical Corp
Priority date: 2017-10-25
Filing date: 2018-10-24
Publication date: 2023-03-28
Anticipated expiration: 2038-10-24
Also published as: TWI772546B; KR102586311B1; CN111263913A; JP7256472B2; JPWO2019082913A1; TW201922853A; KR20200067199A; WO2019082913A1

Abstract

A liquid crystal aligning agent comprising at least 1 polymer selected from the group consisting of a polyimide precursor which is a reaction product of a tetracarboxylic acid derivative and a diamine, and a polyimide which is an imide thereof, and an organic solvent, wherein the organic solvent comprises the following components: component A: at least 1 selected from gamma-butyrolactone and gamma-valerolactone; component B: at least 1 selected from dipropylene glycol dimethyl ether and diacetone alcohol, wherein the content of the component A and the content of the component B are respectively less than 25 wt%, and the content difference between the component A and the component B is less than 5 wt%.

Description

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

Technical Field

The present invention relates to a liquid crystal aligning agent, a liquid crystal alignment film, and a liquid crystal display element suitable for application by an ink jet method (hereinafter referred to as ink jet application).

Background

As the liquid crystal alignment film, a so-called polyimide-based liquid crystal alignment film, which is obtained by applying and baking a liquid crystal alignment agent containing a polyimide precursor such as polyamic acid or a solution of soluble polyimide as a main component, is widely used. As a method for forming such a liquid crystal alignment film, inkjet coating has been the mainstream at present, instead of conventional spin coating, flexographic printing, and the like.

Inkjet coating is a method of forming a film by dropping fine droplets on a substrate and wet diffusion of a liquid. According to this method, the liquid crystal aligning agent can be used efficiently in the liquid crystal panel production process, and the production efficiency of the liquid crystal panel can be improved, thereby enabling the cost reduction of the liquid crystal panel.

The liquid crystal aligning agent used in ink jet coating is required to have small film thickness unevenness inside the coated surface and high film formation accuracy in the peripheral portion of the coating. Meanwhile, it is also important that the organic solvent in the liquid crystal alignment agent does not damage the inkjet head and peripheral members when ejected from the inkjet device.

In order to meet the above-described various requirements, liquid crystal aligning agents for inkjet coating based on an appropriate combination of various solvents have been proposed (see patent documents 1 and 2), and further improvement in characteristics has been desired in accordance with recent high-definition and large-size liquid crystal display devices.

Documents of the prior art

Patent document

Patent document 1: japanese patent application publication No. 2013-507817

Patent document 2: japanese patent application No. 2014-529512

Disclosure of Invention

Problems to be solved by the invention

In view of the above background, an object of the present invention is to provide a liquid crystal aligning agent which is most suitable for inkjet coating by improving various characteristics required for inkjet coating.

The present inventors have conducted various studies to achieve the above object and, as a result, have found that a liquid crystal aligning agent according to the following aspect is most suitable for achieving the above object, and have completed the present invention.

Means for solving the problems

Thus, the present invention has been made based on the above-described knowledge and has the following gist.

1. A liquid crystal aligning agent comprising at least 1 polymer selected from the group consisting of a polyimide precursor which is a reaction product of a tetracarboxylic acid derivative and a diamine, and a polyimide which is an imide compound thereof, and an organic solvent, wherein the organic solvent comprises the following components:

component A: at least 1 selected from gamma-butyrolactone, gamma-valerolactone;

component B: the dimethyl ether of dipropylene glycol,

the contents of the component A and the component B are respectively less than 25 wt%, and the content difference between the component A and the component B is less than 5 wt%.

ADVANTAGEOUS EFFECTS OF INVENTION

By using the liquid crystal aligning agent of the present invention, when the liquid crystal aligning agent is used for ink jet coating, the film thickness unevenness inside the coating surface is small, a liquid crystal alignment film with high film formation precision at the coating peripheral part can be obtained, and the liquid crystal aligning agent does not damage an ink jet head and peripheral members when being ejected from an ink jet device, and as a result, the liquid crystal aligning agent can contribute to the stability of manufacturing of a liquid crystal display element.

Detailed Description

Hereinafter, various features of the present invention will be described in detail.

< organic solvent and composition thereof >

The liquid crystal aligning agent of the present invention contains the following components A and B as organic solvents.

Component A: at least 1 selected from gamma-butyrolactone and gamma-valerolactone

And B component: dipropylene glycol dimethyl ether

The organic solvent of component a is used to dissolve the polymer contained in the liquid crystal aligning agent of the present invention, and is less likely to adversely affect an ink jet head and peripheral members of an ink jet coating apparatus. The component A is preferably gamma-butyrolactone.

The solvent of component B provides the liquid crystal aligning agent of the present invention with good wet diffusion properties when applied to a substrate or a film.

The contents of the components A and B are respectively less than 25 wt%, and the difference between the contents of the components A and B is less than 5 wt%.

Further, it is preferable from the viewpoint of solubility if at least 1 kind selected from the group consisting of N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, and N-butyl-2-pyrrolidone is further contained as the C component.

The organic solvent of component C is a component for dissolving the polymer contained in the liquid crystal aligning agent of the present invention. Preferred specific examples include: n-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone.

When the component C is used, the content thereof is 35 wt% or less, more preferably 30 wt% or less, based on the weight of the entire liquid crystal aligning agent.

< polymers >

The polymer contained in the liquid crystal aligning agent of the present invention is at least 1 polymer selected from a polyimide precursor which is a reaction product of a tetracarboxylic acid derivative and a diamine, and a polyimide which is an imide compound thereof.

The structure of the polymer is not particularly limited, and a tetracarboxylic acid derivative and a diamine described later can be arbitrarily selected according to the characteristics of the liquid crystal aligning agent to be obtained, and among them, a polymer containing a side chain structure of the following formula [1-1] is preferable from the viewpoint of solubility and the like.

Formula [1-1]]In, Y ¹ And Y ³ Each independently represents a group selected from the group consisting of a single bond, - (CH) ₂ ) _a - (a is an integer of 1 to 15), -O-, -CH ₂ At least 1 member of the group consisting of O-, -COO-and-OCO-.

Y ² Represents a single bond or- (CH) ₂ ) _b - (b is an integer of 1 to 15) (wherein, in Y ¹ Or Y ³ Is a single bond, - (CH) ₂ ) _a In the case of-Y ² Is a single bond at Y ¹ Is selected from the group consisting of-O-, -CH ₂ At least 1 of the group consisting of O-, -COO-and-OCO-and/or Y ³ Is selected from the group consisting of-O-, -CH ₂ O-、-CY is at least 1 member of the group consisting of OO-and-OCO- ² Is a single bond or- (CH) ₂ ) _b -)。

Y ⁴ At least 1 type of 2-valent cyclic group selected from the group consisting of benzene ring, cyclohexane ring and heterocycle, or 2-valent organic group having 17-51 carbon atoms and having steroid skeleton, wherein any hydrogen atom on the cyclic group is optionally substituted by alkyl group having 1-3 carbon atoms, alkoxy group having 1-3 carbon atoms, fluorine-containing alkyl group having 1-3 carbon atoms, fluorine-containing alkoxy group having 1-3 carbon atoms or fluorine atom.

Y ⁵ Represents at least 1 cyclic group selected from the group consisting of a benzene ring, a cyclohexane ring and a heterocycle, and any hydrogen atom on these cyclic groups is optionally substituted by an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a fluoroalkyl group having 1 to 3 carbon atoms, a fluoroalkoxy group having 1 to 3 carbon atoms or a fluorine atom.

Y ⁶ Represents at least 1 kind selected from the group consisting of alkyl with 1-18 carbon atoms, alkenyl with 2-18 carbon atoms, fluorine-containing alkyl with 1-18 carbon atoms, alkoxy with 1-18 carbon atoms and fluorine-containing alkoxy with 1-18 carbon atoms. n represents an integer of 0 to 4.

To introduce the side chain structure into the polymer, the following methods may be mentioned: a tetracarboxylic acid derivative or diamine, which is a polymer material, into which the side chain structure is introduced is used. Among them, the use of a diamine having the above side chain structure introduced therein is preferable from the viewpoint of ease of synthesis and the like.

Preferable specific examples of the side chain structure include the following formulas (S1-1) to (S1-22).

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Further, when a process such as ultraviolet irradiation is performed in the process of manufacturing the liquid crystal display element, it is preferable to introduce a photoreactive side chain in which photoreaction is induced by ultraviolet rays of a specific wavelength.

Examples of the photoreactive side chain include a side chain structure represented by the following formula [ VII ]. The side chain structure of the formula [ VII ] has a radical generating structure. The radical generating structure is decomposed by ultraviolet irradiation to generate radicals.

In the formula [ VII ], ar represents at least 1 aromatic hydrocarbon group selected from the group consisting of phenylene, naphthylene and biphenylene, and hydrogen atoms of the rings are optionally substituted by halogen atoms. Since Ar bonded to a carbonyl group affects the absorption wavelength of ultraviolet light, a structure having a long conjugation length such as a naphthylene group or a biphenylene group is preferable in the case of a long wavelength. On the other hand, if Ar has a structure of naphthylene or biphenylene, the solubility may be poor, and in this case, the ease of synthesis may be high. Since sufficient characteristics can be obtained even with a phenyl group if the wavelength of ultraviolet light is in the range of 250nm to 380nm, ar is most preferably a phenyl group.

In the Ar, the aromatic hydrocarbon group may have a substituent. Examples of the substituent herein include electron-donating organic groups such as an alkyl group, a hydroxyl group, an alkoxy group, and an amino group.

Further, the above formula [ VII]In, R ₁ And R ₂ Each independently represents an alkyl group having 1 to 10 carbon atoms, an alkoxy group, a benzyl group or a phenethyl group. In the case of alkyl or alkoxy, the substituent R may be ₁ And R ₂ Forming a ring.

Further, the above formula [ VII]In, T ₁ And T ₂ Each independently represents a single bond, -O-, -COO-, -OCO-, -NHCO-) -CONH-, -NH-, -CH ₂ O-、-N(CH ₃ )-、-CON(CH ₃ ) -or-N (CH) ₃ ) A CO-linking group.

Furthermore, of the formula [ VII]Wherein S represents a single bond, an unsubstituted or fluorine atom-substituted alkylene group having 1 to 20 carbon atoms. Of alkylene groups herein-CH ₂ -or-CF ₂ -optionally substituted by-CH = CH-, optionally substituted by any of the groups listed below, in case these groups are not adjacent to each other: -O-, -COO-) -OCO-) -NHCO-, -CONH-),-NH-, a divalent carbocyclic ring, a divalent heterocyclic ring.

In the formula [ VII ], Q represents a structure selected from the following formula (1 d).

In the formula (1 d), R represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. R ₃ represents-CH ₂ -, -NR-) -O-or-S-.

In the formula [ VII ], Q is preferably an electron-donating organic group, and is preferably an alkyl group, a hydroxyl group, an alkoxy group, an amino group, or the like as exemplified above for Ar. When Q is an amino derivative, a hydroxyl group or an alkoxy group is more preferable because there is a possibility that a salt is formed between the generated carboxylic acid group and the amino group during polymerization of the polyamic acid which is a precursor of the polyimide.

< tetracarboxylic acid derivative >

The polymer contained in the liquid crystal aligning agent of the present invention is at least 1 polymer selected from a polyimide precursor obtained by a reaction of a tetracarboxylic acid derivative and a diamine and a polyimide as an imide compound thereof. Specific examples of the materials used and the production method will be described in detail below.

Examples of the tetracarboxylic acid derivative used for producing the polyimide precursor include not only tetracarboxylic dianhydrides but also tetracarboxylic acids, tetracarboxylic acid dihalides, tetracarboxylic acid dialkyl esters, and tetracarboxylic acid dialkyl ester dihalides as derivatives thereof.

Among these tetracarboxylic acid derivatives, those represented by the following formula (3) are preferred.

In the formula (3), X ₁ The structure of (2) is not particularly limited. Specific examples thereof include the following formulae (X1-1) to (X1-42). Preferred are (X1-1), (X1-2), (X1-5), (X1-7), (X1-8), (X1-10), (X)1-11)、(X1-26)、(X1-27)、(X1-33)、(X1-38)、(X1-40)。

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In the formulae (X1-1) to (X1-4), R ₃ ～R ₂₃ Each independently represents 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. From the viewpoint of liquid crystal alignment, R ₃ ～R ₂ Preferably a hydrogen atom, a halogen atom, a methyl group or an ethyl group, preferably a hydrogen atom or a methyl group.

Specific examples of the formula (X1-1) include the following formulae (X1-1-1) to (X1-1-6). From the viewpoint of liquid crystal alignment properties and polymerization reactivity, (X1-1-1) and (X1-1-2) are particularly preferable.

< diamine >

The diamine used for producing the polyimide precursor is represented by the following formula (4).

In the above formula (4), A ₁ And A ₂ Each independently represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms or an alkynyl group having 2 to 5 carbon atoms.

The structure of the above formula (4) is not particularly limited. Preferred examples of the structure include the diamines having the side chain structure of the formula [1-1 ]. Specific examples thereof include (Y-178), (Y-180) and (Y-181).

In addition, diamines having any structure may be used. Specific examples thereof include the following (Y-1) to (Y-177).

From the viewpoints of ease of production of the polyimide precursor, stability of the liquid crystal aligning agent, characteristics as a liquid crystal alignment film, and the like, (Y-27), (Y-28), (Y-38), (Y-71), (Y-72), (Y-76), (Y-77), (Y-80), (Y-81), (Y-82), (Y-158), (Y-159), (Y-160), (Y-161), and (Y-169) to (Y-188) are preferable.

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In the above formula, me represents a methyl group, R ¹ Represents a hydrogen atom or a hydrocarbon group having 1 to 5 carbon atoms.

< Polyamic acid >

The polyamic acid as the polyimide precursor used in the present invention can be produced by the following method. Specifically, it can be synthesized by reacting a tetracarboxylic dianhydride with a diamine 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 12 hours.

The organic solvent used in the above reaction is preferably N, N-dimethylformamide, N-methyl-2-pyrrolidone or γ -butyrolactone in view of the solubility of the monomer and the polymer, and these may be used in 1 kind or 2 or more kinds may be used in combination. The concentration of the polymer is preferably 1 to 30% by mass, more preferably 5 to 20% by mass, from the viewpoint that precipitation of the polymer is not likely to occur and a high molecular weight product is easily obtained.

The polyamic acid obtained as described above can be recovered by precipitating a polymer by pouring the reaction solution into a poor solvent while sufficiently stirring the reaction solution. Further, the polyamic acid can be obtained as a powder of a purified polyamic acid by precipitation several times, washing with a poor solvent, and drying at room temperature or under heating. The poor solvent is not particularly limited, and examples thereof include: water, methanol, ethanol, hexane, butyl cellosolve, acetone, toluene, and the like.

< polyamic acid ester >

The polyamic acid ester, which is one of the polyimide precursors used in the present invention, can be produced by the method (I), (II), or (III) shown below.

(I) Case of production from Polyamic acid

The polyamic acid ester can be synthesized by esterifying a polyamic acid obtained from a tetracarboxylic dianhydride and a diamine. Specifically, the polyamic acid and the esterifying agent can be synthesized by reacting the polyamic acid and the esterifying agent in the presence of an organic solvent at-20 to 150 ℃ and preferably at 0 to 50 ℃ for 30 minutes to 24 hours and preferably 1 to 4 hours.

The esterification agent is preferably one 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-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, etc. The amount of the esterifying agent to be used is preferably 2 to 6 molar equivalents based on 1 mole of the repeating unit of the polyamic acid.

The solvent used in the above reaction is preferably N, N-dimethylformamide, N-methyl-2-pyrrolidone or γ -butyrolactone in view of the solubility of the polymer, and 1 kind or 2 or more kinds may be used in combination. The concentration of the polymer in the reaction solution is preferably 1 to 30% by mass, more preferably 5 to 20% by mass, from the viewpoint that precipitation of the polymer is not likely to occur and a high molecular weight product is easily obtained.

(II) production by reaction of a tetracarboxylic acid diester dichloride with a diamine

The polyamic acid ester can be made from a tetracarboxylic acid diester dichloride and a diamine. Specifically, the tetracarboxylic acid diester dichloride and the diamine can be synthesized by reacting them at-20 to 150 ℃ and preferably 0 to 50 ℃ for 30 minutes to 24 hours and preferably 1 to 4 hours in the presence of a base and an organic solvent.

As the base, pyridine, triethylamine, 4-dimethylaminopyridine and the like can be used, and pyridine is preferred for the reaction to proceed mildly. The amount of the base to be used is preferably 2 to 4 times by mole relative to the tetracarboxylic acid diester dichloride, from the viewpoint of easy removal and easy availability of 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 the polymer, and 1 kind or 2 or more kinds thereof may be used in combination. The polymer concentration in the reaction solution is preferably 1 to 30% by mass, more preferably 5 to 20% by mass, from the viewpoint that precipitation of the polymer is not likely to occur and a high molecular weight product is easily obtained. In order to prevent hydrolysis of the tetracarboxylic acid diester dichloride, the solvent used in the synthesis of the polyamic acid ester is preferably dehydrated as much as possible, and the mixing of the outside air is preferably prevented in a nitrogen atmosphere.

(III) production by reaction of a tetracarboxylic acid diester with a diamine

The polyamic acid ester can be produced by polycondensing a tetracarboxylic acid diester and a diamine. Specifically, the tetracarboxylic acid diester 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, (2, 3-dihydro-2-thio-3-benzoxazolyl) diphenyl phosphonate, and the like can be used. The amount of the condensing agent to be added is preferably 2 to 3 times by mol based on the tetracarboxylic acid diester.

As the base, a tertiary amine such as pyridine or triethylamine can be used. The amount of the base to be used is preferably 2 to 4 times by mole relative to 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. As the lewis acid, lithium halide such as lithium chloride or lithium bromide is preferable. The amount of the lewis acid to be added is preferably 0 to 1.0 mol per mol of the diamine component.

Among the above-mentioned 3 methods for producing polyamic acid esters, the above-mentioned 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 with sufficient stirring to precipitate a polymer. 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.

< polyimide >

The polyimide used in the present invention can be produced by imidizing the polyamic acid or polyamic acid ester. The imidization rate of the polyimide used in the present invention is not limited to 100%. From the viewpoint of electrical characteristics, it is preferably 20 to 99%. In the case of producing a polyimide from a polyamic acid ester, chemical imidization by adding an alkaline catalyst to the polyamic acid ester solution or a polyamic acid solution obtained by dissolving a polyamic acid ester resin powder in an organic solvent is convenient. Chemical imidization is preferred because the imidization reaction is carried out at a relatively low temperature, and the molecular weight of the polymer is less likely to decrease during the imidization.

Chemical imidization can be carried out by stirring a polyamic acid or polyamic acid ester 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 polymerization reaction described above can be used. Examples of the basic catalyst include: pyridine, triethylamine, trimethylamine, tributylamine, trioctylamine, and the like. Among them, pyridine is preferable because it has a suitable basicity for proceeding the reaction. Further, examples of the acid anhydride include: among acetic anhydride, trimellitic anhydride, pyromellitic anhydride, etc., acetic anhydride is preferred because purification after completion of the reaction is easy if acetic anhydride is used.

The temperature for the imidization reaction is, for example, from-20 ℃ to 120 ℃, preferably from 0 ℃ to 100 ℃, and the reaction time may be from 1 to 100 hours. The amount of the basic catalyst is 0.5 to 30 mol times, preferably 2 to 20 mol times, and the amount of the acid anhydride is 1 to 50 mol times, preferably 3 to 30 mol times, the amount of the acid amide group. The imidization rate of the obtained polymer can be controlled by adjusting the amount of the catalyst, the temperature and the reaction time.

Since the catalyst or the like to be added remains in the polyamic acid ester or the solution after the imidization of the polyamic acid, it is preferable to prepare the liquid crystal aligning agent of the present invention by recovering the obtained imidized polymer and redissolving it in an organic solvent by the following means.

The solution of the polyimide obtained as described above can be poured into a poor solvent while sufficiently stirring to precipitate a polymer. 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: methanol, acetone, hexane, butyl cellosolve, heptane, methyl ethyl ketone, methyl isobutyl ketone, ethanol, toluene, benzene, and the like.

< liquid Crystal alignment agent >

The liquid crystal aligning agent of the present invention is in the form of a solution obtained by dissolving a polymer containing a specific polymer in an organic solvent containing a specific solvent. The molecular weight of the polyimide precursor and the polyimide according to the present invention is preferably 2,000 to 500,000, more preferably 5,000 to 300,000, and still more preferably 10,000 to 100,000 in terms of weight average molecular weight. The number average molecular weight is preferably 1,000 to 250,000, more preferably 2,500 to 150,000, and still more preferably 5,000 to 50,000.

The concentration of the polymer of the liquid crystal aligning agent used in the present invention may be appropriately changed depending on the setting of the thickness of a coating film to be formed, and is preferably 1 wt% or more from the viewpoint of forming a uniform and defect-free coating film, and is preferably 10 wt% or less from the viewpoint of the storage stability of the solution.

< other solvents >

The solvent in the liquid crystal aligning agent of the present invention is preferably one containing the above-mentioned components a, B and further C, but may contain other solvents. As the other solvent, a solvent (also referred to as a good solvent) that dissolves the polyimide precursor and the polyimide is preferably used, and a solvent (also referred to as a poor solvent) that improves the film coatability and surface smoothness of the liquid crystal alignment film when the liquid crystal alignment agent is applied is preferably used. Specific examples of other solvents are given below, but the solvents are not limited to these examples.

Specific examples of the good solvent include: 1, 3-dimethylimidazolidinone, N-dimethylformamide, N-dimethylacetamide, dimethyl sulfoxide, methyl ethyl ketone, cyclohexanone, cyclopentanone, 3-methoxy-N, N-dimethylpropionamide, 4-hydroxy-4-methyl-2-pentanone, and the like.

Specific examples of the poor solvent include: <xnotran> 1- -2- ,2- -1- ,2- ,2- (2- ) ,1- -2- , ,1- ,2- , , ,1- ,2- ,3- ,2- -1- , , ,3- -2- , ,1- ,2- -1- ,2- -2- ,2- -1- ,1- ,2- ,3- ,1- ,2- ,2- -1- , ,1- ,2- ,3- ,1,2- ,1,2- ,1,3- ,1,2- ,1,3- ,1,4- ,2,3- ,1,5- ,2- -2,4- ,2- -1,3- , , , , , , , ,1,2- , , , ,2- ,3- ,2- ,2- , </xnotran> <xnotran> 4- , 3- , 1- , 2- , 2- , , , , ,2- ( ) , , , ,2- ( ) , , , ,1- ( ) , , , , , , , , , , , , , , , 2- (2- ) , , , , , , , , , , , , ,3- ,3- ,3- ,3- ,3- ,3- ,3- , , , , , , , . </xnotran>

Further, as the poor solvent, a solvent represented by the following formula may be used.

R ₂₄ 、R ₂₅ Each independently a linear or branched alkyl group having 1 to 8 carbon atoms. Wherein R is ₂₄ +R ₂₅ Is an integer greater than 3.

In addition, as the poor solvent, in the case where the polyimide precursor and the polyimide contained in the liquid crystal aligning agent have high solubility in the solvent, a solvent represented by the following [ D-1] to [ D-3] may be used.

Formula [ D-1]]In (D) ¹ Represents an alkyl group having 1 to 3 carbon atoms of the formula [ D-2 ]]In (D) ² Represents an alkyl group having 1 to 3 carbon atoms of the formula [ D-3]]In (D) ³ Represents an alkyl group having 1 to 4 carbon atoms.

The liquid crystal aligning agent of the present invention may contain a crosslinkable compound having an epoxy group, an isocyanate group, an oxetanyl group or a cyclocarbonate group, a crosslinkable compound having at least 1 substituent selected from the group consisting of a hydroxyl group, a hydroxyalkyl group and a lower alkoxyalkyl group, or a crosslinkable compound having a polymerizable unsaturated bond.

Various known compounds can be used for such a crosslinkable compound depending on the purpose.

Examples of the crosslinkable compound having an epoxy group include: bisphenol acetone glycidyl ether, phenol novolac epoxy resin, cresol novolac epoxy resin, triglycidyl isocyanurate, tetraglycidylaminodiphenylene, tetraglycidyl-m-xylylenediamine, tetraglycidyl-1, 3-bis (aminoethyl) cyclohexane, tetraphenylglycidyl ether ethane, triphenylglycidyl ether ethane, bisphenol hexafluoroacetyl diglycidyl ether, 1, 3-bis (1- (2, 3-epoxypropoxy) -1-trifluoromethyl-2, 2-trifluoromethyl) benzene, 4-bis (2, 3-epoxypropoxy) octafluorobiphenyl, triglycidyl p-aminophenol, tetraglycidyl m-xylylenediamine, 2- (4- (2, 3-epoxypropoxy) phenyl) -2- (4- (1, 1-bis (4- (2, 3-epoxypropoxy) phenyl) ethyl) phenyl) propane or 1, 3-bis (4- (1- (4- (2, 3-epoxypropoxy) phenyl) -1- (4- (1- (2, 3-epoxypropoxy) phenyl) -1- (4- (2, 3-epoxypropoxy) phenyl) -1-methylethyl) phenoxy) -2-propanol, and the like.

Specific examples of the crosslinkable compound having an oxetanyl group include crosslinkable compounds represented by formulas [4a ] to [4k ] described in international publication No. WO2011/132751 (2011.10.27) on pages 58 to 59.

Specific examples of the crosslinkable compound having a cyclocarbonate group include crosslinkable compounds represented by the formulae [5-1] to [5-42] described in International publication No. WO2012/014898 (published 2012.2.2) on pages 76 to 82.

Specific examples of the crosslinkable compound having at least 1 substituent selected from the group consisting of a hydroxyl group and an alkoxy group include crosslinkable compounds of the formulae [6-1] to [6-48] described on pages 62 to 66 of International publication No. WO2011/132751 (2011.10.27).

Among the above-mentioned crosslinkable compounds, the following compounds are particularly preferably used.

The content of the crosslinkable compound is preferably 0.1 to 150 parts by mass based on 100 parts by mass of the entire polymer component. Among these, in order to perform the crosslinking reaction and exhibit the desired effect, it is preferably 0.1 to 100 parts by mass, and more preferably 1 to 50 parts by mass.

The liquid crystal aligning agent of the present invention may contain a compound that improves the uniformity of the film thickness and surface smoothness of the liquid crystal alignment film when the liquid crystal aligning agent is applied.

Examples of compounds for improving the uniformity of the film thickness and the surface smoothness of the liquid crystal alignment film include: fluorine-based surfactants, silicone-based surfactants, nonionic surfactants, and the like.

The amount of the surfactant to be used is preferably 0.01 to 2 parts by mass, and more preferably 0.01 to 1 part by mass, based on 100 parts by mass of the total polymer components contained in the liquid crystal aligning agent.

< liquid Crystal alignment film, liquid Crystal display element >

The liquid crystal alignment film of the present invention is a film 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 agent. The substrate to which the liquid crystal aligning agent of the present invention 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 may be used. In this case, if a substrate on which an ITO electrode or the like for driving liquid crystal is formed is used, it is preferable in view of process simplification. In addition, if the reflective liquid crystal display element is a single-sided substrate, an opaque material such as a silicon wafer may be used, and in this case, a material that reflects light such as aluminum may be used for the electrodes.

The method of applying the liquid crystal aligning agent is generally industrially performed by screen printing, offset printing, flexographic printing, inkjet method, or the like, and as other application methods, a dipping method, a roll coater method, a slit coater method, a spin coater method, a spray method, or the like is known.

After coating the liquid crystal alignment agent on the substrate, the solvent is evaporated by heating means such as a hot plate, a thermal cycle oven, or an IR (infrared ray) oven, thereby forming a liquid crystal alignment film. The drying and baking steps after the liquid crystal aligning agent is applied can be performed at any temperature and for any time. In general, in order to sufficiently remove the solvent contained, there are included: roasting at 50-120 deg.c for 1-10 min and then at 150-300 deg.c for 5-120 min. If the thickness of the liquid crystal alignment film after baking is too thin, the reliability of the liquid crystal display device may be lowered, and therefore, the thickness is preferably 5 to 300nm, more preferably 10 to 200nm.

The liquid crystal aligning agent of the present invention can be used as a liquid crystal alignment film by applying it on a substrate, baking it, and then performing alignment treatment such as rubbing treatment or photo-alignment treatment, or by not performing alignment treatment in vertical alignment applications. The alignment treatment such as rubbing treatment and photo-alignment treatment may be performed by a known method or apparatus.

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

Specifically, a transparent glass substrate is prepared, a common electrode is provided on one substrate, and a segment electrode is provided on the other substrate. These electrodes may be, for example, ITO electrodes, and are patterned so as to display a desired image. Next, an insulating film is provided on each substrate so as to cover the common electrode and the segment electrodes. The insulating film may be, for example, siO formed by a sol-gel method ₂ -TiO ₂ The film of (1).

Next, liquid crystal alignment films are formed on the respective substrates, one substrate is stacked on the other substrate so that the liquid crystal alignment films face each other, and the periphery is bonded with a sealant. In the sealing agent, in order to control the substrate gap, it is generally preferable to mix spacers in advance, and to disperse spacers for controlling the substrate gap in advance also in a portion of the surface where the sealing agent is not provided. An opening portion into which liquid crystal can be filled from the outside is provided in advance in a part of the sealant. Next, a liquid crystal material was injected into the space surrounded by the 2 substrates and the sealant through the opening provided in the sealant, and then the opening was sealed with an adhesive. The implantation may be performed by a vacuum implantation method or a method using a capillary phenomenon in the atmosphere. The liquid crystal material may be either a positive-type liquid crystal material or a negative-type liquid crystal material, and is preferably a negative-type liquid crystal material. Next, a polarizing plate is provided. Specifically, a pair of polarizing plates was attached to the surfaces of the 2 substrates opposite to the liquid crystal layer.

Examples

The present invention will be described more specifically with reference to the following examples, but the present invention is not limited to these examples. The following compounds are abbreviated as symbols and the measurement methods of the properties are as follows.

< Tetracarboxylic dianhydride >

CBDA:1,2,3, 4-cyclobutanetetracarboxylic dianhydride

BODA: bicyclo [3,3,0] octane-2, 4,6, 8-tetracarboxylic dianhydride

DSDA:3,3',4,4' -Diphenylsulphonetetracarboxylic dianhydride

And (3) PMDA: pyromellitic anhydride

< diamine >

DA-1: p-phenylene diamine

DA-2:4, 4-diaminodiphenylmethane

DA-3:3, 5-diaminobenzoic acid

D-4: 3, 5-diamino-N- (pyridin-3-ylmethyl) benzamide

DA-5:4,4' - [ isopropylidene-bis (p-phenylene) oxy) ] diphenylamine

DA-6: diamines of the formula DA-6

DA-7:1- (4- (2, 4-diaminophenoxy) ethoxy) phenyl) -2-hydroxy-2-methylpropanone

DA-8:1, 3-diamino-4- [4- (trans-4-n-heptylcyclohexyl) phenoxy ] benzene

DA-9:1, 3-diamino-4- [ trans-4- (pentylcyclohexyl) -cyclohexyl ] phenoxy ] benzene

< structures of DA-1 to DA-9 >

< additives >

TM-BIP-A:2,2' -bis (4-hydroxy-3, 5-dihydroxymethylphenyl) propane

< organic solvent >

NMP: 1-methyl-2-pyrrolidone

NEP: 1-Ethyl-2-pyrrolidone

GBL: gamma-butyrolactone

BCS: butyl cellosolve

PB: 1-butoxy-2-propanol

DME: dipropylene glycol dimethyl ether

And (3) DIBK: diisobutyl ketone

In the examples, the molecular weights and imidization ratios of polyamic acid and polyimide were evaluated as follows.

< measurement of molecular weight >

The molecular weights of the polyamic acid and polyimide were measured by using a Gel Permeation Chromatography (GPC) apparatus (GPC-101) manufactured by Showa Denko K.K., and using columns (KD-803, KD-805) manufactured by SHOWANDENKO K.K.. The measurement conditions were as follows.

Column temperature: 50 deg.C

Eluent: n, N' -dimethylformamide (additive: lithium bromide-hydrate (LiBr. H2O) 30mmol/L, phosphoric acid-anhydrous crystal (orthophosphoric acid) 30mmol/L, tetrahydrofuran (THF) 10 ml/L)

Flow rate: 1.0 ml/min

Standard curve drawing standard samples: TSK standard polyethylene oxide (molecular weight: about 900,000, 150,000, 100,000, 30,000) manufactured by Tosoh corporation and polyethylene glycol (molecular weight: about 12,000, 4,000, 1,000) manufactured by Polymer Laboratories Ltd.

< measurement of imidization Rate >

20mg of the polyimide powder was charged into an NMR sample tube (NMR standard sample tube φ 5, manufactured by Nippon Seisakusho Co., ltd.), 0.53ml of deuterated dimethyl sulfoxide (DMSO-d 6, 0.05% TMS (tetramethylsilane) mixture) was added thereto, and the mixture was completely dissolved by applying ultrasonic waves. For this solution, proton NMR at 500MHz was measured using an NMR measuring instrument (JNW-ECA 500) manufactured by JEOL DATUM LTD. The imidization ratio is determined from the following equation (1) by using the peak cumulative value of the proton derived from the structure which does not change before and after imidization as a reference proton and the peak cumulative value of the proton derived from the NH group of amic acid appearing in the vicinity of 9.0 to 11.0 ppm.

Imidization ratio (%) = (1-. Alpha.x/y). Times.100 \8230; (1)

In the formula (1), x is a peak cumulative value of a proton derived from an NH group of amic acid, y is a peak cumulative value of a reference proton, and α is a ratio of the number of reference protons to 1 NH atom of amic acid in the case of polyamic acid (imidization ratio of 0%).

< Synthesis example 1>

BODA (22.27g, 89mmol), DA-7 (14.70g, 44.5 mmol), DA-4 (12.94g, 53.4 mmol), DA-9 (19.34g, 44.5 mmol) and DA-8 (13.55g, 35.6 mmol) were mixed with NMP (331.2 g) and reacted at 60 ℃ for 3 hours, then CBDA (16.93g, 86.3 mmol) and NMP (67.2 g) were added and reacted at 40 ℃ for 15 hours to obtain a polyamic acid solution (a). The polyamic acid solution (a) had a number average molecular weight of 22,000 and a weight average molecular weight of 58,000. NMP was added to the polyamic acid solution (a) (498.13 g) to dilute the solution so that the content of the polyamic acid solution (a) was 10% by mass, and then acetic anhydride (90.87 g) and pyridine (28.16 g) were added as imidization catalysts to react at 70 ℃ for 3.5 hours. The reaction solution was poured into methanol (5,000ml), and the resulting precipitate was filtered off. The precipitate was washed with methanol and dried under reduced pressure at 100 ℃ to obtain polyimide (A). The imidization ratio of the polyimide (A) was 72%.

< Synthesis example 2>

BODA (23.02g, 92mmol), DA-3 (14.0g, 92mmol), DA-5 (22.66g, 55.2mmol) and DA-8 (14.01g, 36.8mmol) were mixed with NMP (294.73 g), and after 1 hour of reaction at 60 ℃, CBDA (6.68g, 34.0mmol) and NMP (26.7 g) were added, and after 1 hour of reaction at 20 ℃, DSDA (19.78g, 55.2mmol) and NMP (79.11 g) were added, and after 2 hours of reaction at 40 ℃, polyamic acid solution (b) was obtained. The polyamic acid solution (b) had a number-average molecular weight of 17,000 and a weight-average molecular weight of 45,000. To the polyamic acid solution (b) (500.69 g) was added NMP to dilute the solution so that the content of the polyamic acid solution (b) was 6.5% by mass, and then acetic anhydride (93.93 g) and pyridine (72.77 g) were added as imidization catalysts to conduct a reaction at 75 ℃ for 3.5 hours. The reaction solution was poured into methanol (5,000ml), and the resulting precipitate was filtered off. The precipitate was washed with methanol and dried under reduced pressure at 100 ℃ to obtain polyimide (B). The imidization ratio of the polyimide (B) was 74%.

< Synthesis example 3>

BODA (25.02g, 100mmol), DA-1 (8.65g, 80mmol), DA-6 (6.83g, 20mmol) and DA-8 (38.6g, 100mmol) were mixed with NMP (214.2 g), and reacted at 60 ℃ for 3 hours, then CBDA (19.61g, 100mmol) and NMP (178.5 g) were added, and reacted at 40 ℃ for 15 hours to obtain a polyamic acid solution (c). The polyamic acid solution (c) had a number-average molecular weight of 23,000 and a weight-average molecular weight of 60,000. NMP was added to the polyamic acid solution (c) (450.0 g) to dilute the solution so that the content of the polyamic acid solution (a) was 10% by mass, and then acetic anhydride (103.6 g) and pyridine (32.11 g) were added as imidization catalysts to react at 70 ℃ for 3.5 hours. The reaction solution was poured into methanol (3,600ml), and the resulting precipitate was filtered off. The precipitate was washed with methanol and dried under reduced pressure at 100 ℃ to obtain polyimide (C). The imidization rate of the polyimide (C) was 69%.

< Synthesis example 4>

BODA (25.02g, 100mmol), DA-7 (6.60g, 20mmol), DA-2 (23.79g, 120mmol) and DA-9 (26.1g, 60mmol) were mixed in NMP (225.9 g), and after reaction at 60 ℃ for 3 hours, CBDA (19.61g, 100mmol) and NMP (178.5 g) were added, and reaction at 40 ℃ for 15 hours was carried out to obtain a polyamic acid solution (d). The polyamic acid solution (d) had a number-average molecular weight of 24,000 and a weight-average molecular weight of 62,000. NMP was added to the polyamic acid solution (d) (450.0 g) to dilute the solution so that the content of the polyamic acid solution (d) was 10 mass%, and then acetic anhydride (90.9 g) and pyridine (28.17 g) were added as imidization catalysts to react at 70 ℃ for 3.5 hours. The reaction solution was poured into methanol (3,600ml), and the resulting precipitate was filtered off. The precipitate was washed with methanol and dried under reduced pressure at 100 ℃ to obtain polyimide (D). The imidization rate of the polyimide (D) was 73%.

< Synthesis example 5>

BODA (25.02g, 100mmol), DA-3 (12.17g, 80mmol), DA-4 (14.53g, 60mmol), DA-8 (22.83g, 60mmol) were mixed in NMP (198.17 g), reacted at 60 ℃ for 3 hours, then PMDA (8.72g, 40mmol) and NMP (34.9 g) were added, and reacted at 40 ℃ for 3 hours. Finally, CBDA (11.76g, 60mmol) and NMP (147.15 g) were added and reacted for 15 hours to obtain polyamic acid solution (e). The polyamic acid solution (e) had a number average molecular weight of 25,000 and a weight average molecular weight of 65,000. NMP was added to the polyamic acid solution (e) (450.0 g) to dilute the polyamic acid solution (d) so that the content thereof was 10% by mass, and acetic anhydride (96.7 g) and pyridine (29.97 g) were added as imidization catalysts to conduct a reaction at 70 ℃ for 3.5 hours. The reaction solution was poured into methanol (3,600ml), and the resulting precipitate was filtered off. The precipitate was washed with methanol and dried under reduced pressure at 100 ℃ to obtain polyimide (E). The imidization ratio of the polyimide (E) was 72%.

< example 1>

NEP (198 g) was added to the polyimide (A) (13.5 g) obtained in Synthesis example 1 and the polyimide (B) (13.5 g) obtained in Synthesis example 2, and the mixture was stirred at 70 ℃ for 20 hours to dissolve the NEP. NEP (17.91 g), GBL (151.2 g), PB (180 g), DME (144 g), and TM-BIP-A (1.89 g) were added to the solution, and the mixture was stirred at 25 ℃ for 2 hours. The solution was filtered through a filter having a pore size of 1 μm to prepare a liquid crystal aligning agent [ A ] of the present invention.

< example 2>

NMP (150.73 g) was added to the polyimide (A) (13.3 g) obtained in Synthesis example 1 and the polyimide (B) (13.3 g) obtained in Synthesis example 2, and the mixture was stirred at 70 ℃ for 20 hours to dissolve the compounds, NMP (65.30 g), GBL (115.02 g), BCS (251.6 g), DME (107.8 g) and TM-BIP-A (1.86 g) were added to the solution, and the solution was stirred at 25 ℃ for 2 hours, and the solution was filtered through a filter having a pore size of 1 μm to prepare a liquid crystal aligning agent [ B ] of the present invention.

< example 3>

NMP (150.73 g) was added to the polyimide (C) (13.3 g) obtained in Synthesis example 3 and the polyimide (E) (13.3 g) obtained in Synthesis example 5, and the mixture was stirred at 70 ℃ for 20 hours to dissolve them. To the solution were added NMP (65.30 g), GBL (115.02 g), BCS (251.6 g), DME (107.8 g), TM-BIP-A (1.86 g), and the mixture was stirred at 25 ℃ for 2 hours. The solution was filtered through a filter having a pore size of 1 μm to prepare a liquid crystal aligning agent [ C ] of the present invention.

< example 4>

NEP (198 g) was added to the polyimide (D) (13.5 g) obtained in Synthesis example 4 and the polyimide (E) (13.5 g) obtained in Synthesis example 5, and the mixture was stirred at 70 ℃ for 20 hours to dissolve the NEP. To the solution were added NEP (17.91 g), GBL (151.2 g), PB (180 g), DME (144 g), and TM-BIP-A (1.86 g), and the mixture was stirred at 25 ℃ for 2 hours. The solution was filtered through a filter having a pore size of 1 μm to prepare a liquid crystal aligning agent [ D ] of the present invention.

< example 5>

NEP (150.73 g) was added to the polyimide (A) (13.3 g) obtained in Synthesis example 1 and the polyimide (E) (13.3 g) obtained in Synthesis example 5, and the mixture was stirred at 70 ℃ for 20 hours to dissolve the NEP. To the solution were added NEP (65.30 g), GBL (115.02 g), BCS (251.6 g), DME (107.8 g), and TM-BIP-A (1.86 g), and the mixture was stirred at 25 ℃ for 2 hours. The solution was filtered through a filter having a pore size of 1 μm to prepare a liquid crystal aligning agent [ E ] of the present invention.

< comparative example 1>

NEP (198 g) was added to the polyimide (A) (13.5 g) obtained in Synthesis example 1 and the polyimide (B) (13.5 g) obtained in Synthesis example 2, and the mixture was stirred at 70 ℃ for 20 hours to dissolve the NEP. To the solution were added NEP (169.11 g), PB (216 g), DME (108 g), and TM-BIP-A (1.89 g), and the mixture was stirred at 25 ℃ for 2 hours. The solution was filtered through a filter having a pore size of 1 μm to prepare a liquid crystal aligning agent [ F ].

< comparative example 2>

NEP (148.59 g) was added to the polyimide (A) (10.13 g) obtained in Synthesis example 1 and the polyimide (B) (10.13 g) obtained in Synthesis example 2, and the mixture was stirred at 70 ℃ for 20 hours to dissolve them. NEP (261.67 g), PB (287.95 g), and TM-BIP-A (1.42 g) were added to the solution, and the mixture was stirred at 25 ℃ for 2 hours. The solution was filtered through a filter having a pore size of 1 μm to prepare a liquid crystal aligning agent [ G ].

< comparative example 3>

NEP (195.07 g) was added to the polyimide (A) (13.3 g) obtained in Synthesis example 1 and the polyimide (B) (13.3 g) obtained in Synthesis example 2, and the mixture was stirred at 70 ℃ for 20 hours to dissolve them. NEP (202.08 g), PB (212.79 g), DIBK (70.93 g), and TM-BIP-A (1.86 g) were added to the solution, and the mixture was stirred at 25 ℃ for 2 hours. The solution was filtered through a filter having a pore size of 1 μm to prepare a liquid crystal aligning agent [ H ].

[ method for Forming and evaluating coating film ]

The prepared liquid crystal aligning agent is coated on a substrate by an ink jet method, and is subjected to predrying and main baking to form a coating film. Evaluation of ink jet coating was carried out under the following conditions using an ink jet device (model IJ-1021) manufactured by SHIBURAMECHANTRONICS CORPORATION.

Inkjet coating conditions:

head (shower Head): h18 H1A

Nozzle No./Head (number of nozzles/Head) =256

Head Nozzle Pitch: 396.88um

Head Offset: 198.43um

Scan number: 2Scan

Drop Pitch (droplet Pitch, X) in Head arrangement direction: 99.22um

The speed of the workbench: 512mm/sec, frequency: 4000Hz

Drop Pitch (droplet Pitch, Y) in the table movement direction: 128um

Coating pattern set value: 80mm x 80mm

Film thickness:

substrate: for evaluation of Halo (Halo) region, a glass substrate of 100X 100mm having a Cr or ITO electrode on the entire surface of one side was used. The TFT substrate was used for evaluation of the unevenness (C/H unevenness) around the Contact hole.

Standing time from the end of coating to predrying: 45 seconds

Pre-drying: the substrate was placed on a pin (pin) having a height of 1mm set upright on a hot plate set at 90 ℃ and dried for 40 seconds.

Main roasting: 230 ℃/20 minutes (IR oven)

< evaluation method of Halo region >

The Halo region at the edge of the liquid crystal alignment film was evaluated by observing changes in color tone (film thickness unevenness) at the edge of the coating film in the upper, lower, left, and right directions with an optical microscope (manufactured by NIKON CORPORATION, ECLIPSE L300N) with respect to the coating direction. Specifically, observation was performed with an optical microscope at a magnification of 2.5, and the length of the change in color tone (film thickness unevenness) of the obtained coating film image was measured. All coating film images were obtained at the same magnification. The average value of the color tone changes (film thickness unevenness) at the coating film ends of the upper, lower, left and right sides was evaluated as "poor" of 7mm or more, Δ of 6mm to 5mm, and good of less than 5 mm.

< method for evaluating C/H unevenness >

When the surface of the coating film obtained above was observed with an optical microscope at a magnification of 5 times, the number of unevenness around C/H was 20% or less of the number of C/H in the visual field and was marked as "o", and those higher than this were marked as "x".

The following table shows the evaluation results of the liquid crystal aligning agents obtained in examples 1 to 5 and comparative examples 1 to 3.

[ Table 1]

Industrial applicability

The liquid crystal aligning agent of the present invention is industrially useful for solving display unevenness in the vicinity of a frame by improving the adhesiveness between a sealant and a liquid crystal alignment film in a narrow-frame liquid crystal display element capable of securing a large display area.

Claims

1. A liquid crystal aligning agent comprising at least 1 polymer selected from the group consisting of a polyimide precursor which is a reaction product of a tetracarboxylic acid derivative and a diamine, and a polyimide which is an imide thereof, and an organic solvent, wherein the organic solvent comprises the following components:

component A: at least 1 selected from gamma-butyrolactone and gamma-valerolactone;

component B: at least 1 selected from dipropylene glycol dimethyl ether and diacetone alcohol;

and C, component C: at least 1 kind selected from N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, and N-butyl-2-pyrrolidone,

the contents of the component A and the component B are respectively less than 25 wt%, the content difference between the component A and the component B is less than 5 wt%,

the component C is 35 wt% or less based on the weight of the entire liquid crystal aligning agent;

wherein the polymer has a photoreactive side chain that initiates a photoreaction by ultraviolet light of a specific wavelength, the photoreactive side chain having a side chain structure represented by the following formula [ VII ],

in the formula [ VII ], ar represents at least 1 aromatic hydrocarbon group selected from the group consisting of phenylene, naphthylene and biphenylene, the hydrogen atom of the ring of the aromatic hydrocarbon group is optionally substituted by halogen atom, in the Ar, the aromatic hydrocarbon group is optionally provided with a substituent,

R ₁ and R ₂ Each independently represents an alkyl group having 1 to 10 carbon atoms, an alkoxy group, a benzyl group or a phenethyl group, and in the case of an alkyl group or an alkoxy group, R is optionally substituted ₁ And R ₂ Forming a ring,

T ₁ and T ₂ Each independently represents a single bond, -O-, -COO-, -OCO-, -NHCO-) -CONH-, -NH-, -CH ₂ O-、-N(CH ₃ )-、-CON(CH ₃ ) -or-N (CH) ₃ ) A linking group of CO < - >,

s represents a single bond, an unsubstituted or fluorine atom-substituted alkylene group having 1 to 20 carbon atoms, -CH ₂ -or-CF ₂ -optionally substituted by-CH = CH-, optionally substituted by any of the groups listed below, in case these groups are not adjacent to each other: <xnotran> -O-, -COO-, -OCO-, -NHCO-, -CONH-, -NH-, , , </xnotran>

Q represents a structure selected from the following formula (1 d),

in the formula (1 d), R represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms ₃ represents-CH ₂ -, -NR-) -O-or-S-.

2. The liquid crystal aligning agent according to claim 1, wherein the polymer has a side chain structure of the following formula [1-1 ]:

formula [1-1]]In, Y ¹ And Y ³ Each independently represents a group selected from a single bond, - (CH) ₂ ) _a -、-O-、-CH ₂ At least 1 of the group consisting of O-, -COO-and-OCO-, a is an integer of 1 to 15;

Y ² represents a single bond or- (CH) ₂ ) _b -, b is an integer of 1 to 15, wherein, in Y ¹ Or Y ³ Is a single bond, - (CH) ₂ ) _a In the case of (A) Y ² Is a single bond at Y ¹ Is selected from the group consisting of-O-, -CH ₂ At least 1 of the group consisting of O-, -COO-and-OCO-and/or Y ³ Is selected from the group consisting of-O-, -CH ₂ Y is at least 1 member of the group consisting of O-, -COO-and-OCO- ² Is a single bond or- (CH) ₂ ) _b -；

Y ⁴ Represents at least 1 2-valent cyclic group selected from the group consisting of a benzene ring, a cyclohexane ring and a heterocycle, or a 2-valent organic group having 17 to 51 carbon atoms and having a steroid skeleton, wherein any hydrogen atom on the cyclic group is optionally substituted by an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a fluorine-containing alkyl group having 1 to 3 carbon atoms, a fluorine-containing alkoxy group having 1 to 3 carbon atoms or a fluorine atom;

Y ⁵ represents at least 1 cyclic group selected from the group consisting of a benzene ring, a cyclohexane ring and a heterocycle, and any hydrogen atom on these cyclic groups is optionally substituted by an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a fluorine-containing alkyl group having 1 to 3 carbon atoms, a fluorine-containing alkoxy group having 1 to 3 carbon atoms or a fluorine atom;

Y ⁶ represents at least 1 kind selected from the group consisting of alkyl with 1-18 carbon atoms, alkenyl with 2-18 carbon atoms, fluorine-containing alkyl with 1-18 carbon atoms, alkoxy with 1-18 carbon atoms and fluorine-containing alkoxy with 1-18 carbon atoms; n represents an integer of 0 to 4.

3. The liquid crystal aligning agent according to claim 1 or 2, wherein the tetracarboxylic acid derivative comprises a tetracarboxylic dianhydride represented by the following formula [3 ]:

formula [3]In, X ₁ Is a C4-13 organic group having a valence of 4 and contains a C4-10 non-aromatic cyclic hydrocarbon group.

4. The liquid crystal aligning agent according to claim 3, wherein X ₁ The structure is shown in the following formula:

R ₃ ～R ₆ 、R ₂₄ 、R ₂₅ each independently represents 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.

5. A liquid crystal alignment film obtained from the liquid crystal aligning agent according to any one of claims 1 to 4.

6. A liquid crystal display element comprising the liquid crystal alignment film according to claim 5.