CN109952531B

CN109952531B - Liquid crystal aligning agent, liquid crystal alignment film, and liquid crystal display element

Info

Publication number: CN109952531B
Application number: CN201780070436.XA
Authority: CN
Inventors: 国见奈穗; 杉山崇明
Original assignee: Nissan Chemical Corp
Current assignee: Nissan Chemical Corp
Priority date: 2016-11-18
Filing date: 2017-11-15
Publication date: 2022-12-27
Anticipated expiration: 2037-11-15
Also published as: CN109952531A; KR20190082293A; WO2018092811A1; KR102483499B1; JPWO2018092811A1; JP7259328B2; TW201831658A; TWI745488B

Abstract

The invention provides a liquid crystal aligning agent which can obtain a liquid crystal aligning film with high film hardness and good afterimage characteristics. The liquid crystal aligning agent contains the following component (A), component (B) and an organic solvent. Component (A): the polyimide is an imide compound of a polyimide precursor which is a reaction product of a tetracarboxylic acid derivative component and a diamine component containing a diamine having a structure represented by the following formula (1), and has an imidization ratio of 20 to 80%. (wherein, represents a bond with other atom or group) component (B): the compound contains at least 2 crosslinkable functional groups.

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 obtained from the liquid crystal aligning agent, and a liquid crystal display element using the liquid crystal alignment film.

Background

A liquid crystal alignment film is a film for controlling the alignment of liquid crystal molecules in a liquid crystal display element or a retardation plate using polymerizable liquid crystal in a constant direction. For example, the liquid crystal display element has the following structure: liquid crystal molecules constituting the liquid crystal layer are sandwiched between liquid crystal alignment films formed on respective surfaces of the pair of substrates. Then, the liquid crystal molecules are aligned in a constant direction with a pretilt angle by the liquid crystal alignment film, and respond by applying a voltage to an electrode provided between the substrate and the liquid crystal alignment film. As a result, the liquid crystal display element displays a desired image using a change in orientation due to the response of the liquid crystal molecules. The liquid crystal alignment film forms a main component together with liquid crystal molecules and the like in the liquid crystal display element.

Various characteristics are required for the liquid crystal alignment film. High resistance to brushing is one of the important features. The brushing treatment is known as a method of forming a liquid crystal alignment film from a polymer film formed on a substrate in the manufacturing process of a liquid crystal display element, and is still widely used industrially at present. In the rubbing treatment, an alignment treatment is performed in which a surface of a polymer film such as polyimide formed on a substrate is rubbed with cloth.

In this brushing treatment, it is known that dust generated by scratching the liquid crystal alignment film and scratches adhering to the liquid crystal alignment film deteriorate the display quality of the display element. Therefore, the liquid crystal alignment film is required to have a brushing resistance treatment (brushing resistance) with a high film hardness.

As a method for forming a liquid crystal alignment film having high rubbing resistance, it is known that a liquid crystal alignment film exhibiting a constant pretilt angle can be obtained regardless of the rubbing conditions by using a liquid crystal aligning agent containing a polymer obtained by reacting a tetracarboxylic dianhydride with an amine compound and/or an imidized polymer thereof, and a compound having 2 or more epoxy groups in the molecule (see patent documents 1 and 2).

Documents of the prior art

Patent literature

Patent document 1: japanese patent laid-open publication No. H07-234410

Patent document 2: japanese patent laid-open publication No. 10-338880

Disclosure of Invention

Problems to be solved by the invention

In recent years, for mobile applications such as smartphones and mobile phones, weight reduction and thickness reduction of liquid crystal display elements have been rapidly advanced. Meanwhile, in the manufacture of a liquid crystal panel, a so-called "thinning step" of polishing a glass substrate of the liquid crystal panel after the manufacture is often performed. In this step, there are a chemical method using hydrofluoric acid or the like and a physical polishing method using a polishing agent.

In the case of performing physical rubbing, the manufactured liquid crystal panel may be bent due to a difference in the device used for rubbing, and as a result, stress is applied to the liquid crystal alignment film from all directions. Therefore, when the mechanical strength of the liquid crystal alignment film is weak, breakage of the film occurs particularly around the columnar spacers, which may cause defect generation. The liquid crystal alignment film having sufficient resistance to the rubbing treatment has not been generally sufficient in resistance to the thinning process.

The main object of the present invention is to provide a liquid crystal aligning agent which can obtain a liquid crystal alignment film comprising: the liquid crystal display device has high film hardness capable of suppressing abrasion, cracking, and the like of a film not only in a brushing process but also in a thinning process, has high yield in manufacturing of a liquid crystal panel, has excellent electrical characteristics, and can reduce image sticking caused by alternating current driving generated in a liquid crystal display element of an IPS driving method or an FFS driving method.

Means for solving the problems

The present inventors have conducted extensive studies to solve the above-mentioned problems, and as a result, the present invention has been completed.

That is, the gist of the present invention is a liquid crystal aligning agent comprising the following component (a), component (B) and an organic solvent, a liquid crystal alignment film obtained from the liquid crystal aligning agent, and a liquid crystal display element using the liquid crystal alignment film.

(A) The components: the polyimide is an imide compound of a polyimide precursor which is a reaction product of a tetracarboxylic acid derivative component and a diamine component containing a diamine having a structure represented by the following formula (1), and has an imidization ratio of 20 to 80%.

(wherein, represents a bond with another atom or group.)

(B) The components: a compound having 2 or more crosslinkable functional groups.

ADVANTAGEOUS EFFECTS OF INVENTION

The liquid crystal alignment agent of the present invention can provide a liquid crystal alignment film having high film hardness and good afterimage characteristics. Therefore, the liquid crystal alignment film obtained from the liquid crystal alignment agent of the present invention can provide a liquid crystal display element of IPS drive system or FFS drive system: the liquid crystal display panel has a high yield in manufacturing, has excellent image sticking characteristics, and can reduce image sticking caused by AC driving occurring in liquid crystal display elements of an IPS driving method or an FFS driving method.

Detailed Description

< ingredient (A) >

The component (a) contained in the liquid crystal aligning agent of the present invention is polyimide which is an imide product of a polyimide precursor which is a reaction product of a tetracarboxylic acid derivative component and a diamine component containing a diamine having the structure of the formula (1), and the imidization ratio is 20% to 80%.

Examples of the diamine having the structure of formula (1) include: in formula (1), amino groups are bonded to both ends of the benzene ring. In this case, the amino groups bonded to both ends of the benzene ring are opposite to-O-CH ₂ -O-is each independently bonded in ortho, meta or para position. Among them, preferred is an amino group relative to-O-CH ₂ And both-O-are bonded in the para position.

In order to more favorably achieve the object of the present invention, the content ratio of the diamine having the structure of formula (1) in all the diamine components reacted with the tetracarboxylic acid derivative component is preferably 10 to 80 mol%, more preferably 20 to 60 mol%, and particularly preferably 20 to 50 mol%.

The diamine component for obtaining the polyimide precursor may contain 1 or 2 or more kinds of other diamines in addition to the diamine having the structure of the formula (1). The other diamine can be represented by the following formula (6).

In the above formula (6), 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. From the viewpoint of liquid crystal alignment, A ₁ And A ₂ Preferably a hydrogen atom, or a methyl group.

Further, Y in the formula (6) is exemplified ₁ Examples thereof include the following (Y-1) to (Y-168).

Y in the above formula (6) from the viewpoint of liquid crystal alignment ₁ The structure having high linearity is preferable, and the structure represented by the following formula (8) or the following formula (9) can be exemplified.

In the above formulae (8) and (9), A ₁ Is a single bond, an ester bond, an amido bond, a thioester bond or a 2-valent organic group with 1 to 20 carbon atoms. A. The ₂ Hydrogen atom, halogen atom, hydroxyl group, amino group, thiol group, nitro group, phosphate group, or C1-20 organic group. a is an integer of 1 to 4. When a is 2 or more, A ₂ The structures of (a) may be the same or different. b and c are each independently an integer of 1 to 2.

Specific examples of the above formula (8) and the above formula (9) include: <xnotran> Y-7, Y-25, Y-26, Y-27, Y-43, Y-44, Y-45, Y-46, Y-48, Y-71, Y-72, Y-73, Y-74, Y-75, Y-76, Y-82, Y-87, Y-88, Y-89, Y-90, Y-92, Y-93, Y-94, Y-95, Y-96, Y-100, Y-101, Y-102, Y-103, Y-104,Y-105, Y-106, Y-110, Y-111, Y-112, Y-113, Y-115, Y-116, Y-121, Y-122, Y-126, Y-127, Y-128, Y-129, Y-132, Y-134, Y-153, Y-156, Y-157, Y-158, Y-159, Y-160, Y-161, Y-162, Y-163, Y-164, Y-165, Y-166, Y-167 Y-168. </xnotran>

Among the other diamines contained in the diamine component for obtaining the polyimide precursor, a diamine having a heat-leaving group represented by the following formula (7) which leaves by heat and can generate an amino group, preferably a secondary amino group, is preferable.

In the above formula (7), D is a heat leaving group which leaves preferably at 150 to 230 ℃ and more preferably at 180 to 230 ℃. D is particularly preferably tert-butoxycarbonyl or 9-fluorenylmethoxycarbonyl from the viewpoint of leaving temperature.

Y as a thermally leaving group represented by the above formula (7) ₁ Specific examples of (3) include: y-158, Y-159, Y-160, Y-161, Y-162 or Y-163.

The content ratio of the diamine having the structure of the formula (7) in all the diamine components reacted with the tetracarboxylic acid derivative component is preferably 10 to 70 mol%, more preferably 20 to 50 mol%.

< tetracarboxylic acid derivative >

As the tetracarboxylic acid derivative component which reacts with the diamine component containing the diamine having the structure of the above formula (1) and is used for producing the component (a) contained in the liquid crystal aligning agent of the present invention, not only tetracarboxylic acid dianhydride but also tetracarboxylic acid, tetracarboxylic acid dihalide, tetracarboxylic acid dialkyl ester or tetracarboxylic acid dialkyl ester dihalide can be used. Among these, tetracarboxylic dianhydride is preferable as the tetracarboxylic acid derivative.

As the tetracarboxylic acid derivative, a tetracarboxylic acid derivative having an alicyclic structure is preferable, and specific examples of the alicyclic structure include the following formulae (X1-1) to (X1-10).

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 and containing a fluorine atom, or a phenyl group. From the viewpoint of liquid crystal alignment, R ₃ ～R ₂₃ Preferably 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 formula (X1-1) include the following structures.

In the present invention, the content ratio of the tetracarboxylic acid derivative having an alicyclic structure in all the tetracarboxylic acid derivative components reacted with the diamine component is preferably 60 to 100 mol%, more preferably 70 to 100 mol%, and particularly preferably 80 to 100%.

As the tetracarboxylic acid derivative used in the present invention, a tetracarboxylic acid derivative having a structure other than the tetracarboxylic acid derivative having the above-described alicyclic structure can be used. Specific examples thereof include tetracarboxylic acid derivatives having the following structures (X-9) to (X-42).

< polyimide precursor >

The polyamic acid and polyamic acid ester, which are precursors of the polyimide contained in the liquid crystal aligning agent of the present invention, are produced by (polycondensation) reaction of the tetracarboxylic acid derivative component and the diamine component as described above.

< method for producing Polyamic acid >

Specifically, the polyamic acid can be produced by reacting a tetracarboxylic dianhydride and a diamine in the presence of an organic solvent at-20 to 150 ℃, preferably 0 to 50 ℃, for 30 minutes to 24 hours, preferably 1 to 12 hours.

The organic solvent used in the above reaction is not particularly limited as long as it dissolves the polyimide precursor formed. Examples thereof include: n-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, gamma-butyrolactone, N-dimethylformamide, N-dimethylacetamide, dimethylsulfoxide, or 1,3-dimethyl-imidazolidinone.

When the solubility of the polyamic acid is high, methyl ethyl ketone, cyclohexanone, cyclopentanone, 4-hydroxy-4-methyl-2-pentanone, or a solvent represented by the following formulas [ D-1] to [ D-3] can be used.

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

These solvents may be used alone or in combination. Further, even if the solvent does not dissolve the polyamic acid, the solvent may be used in combination within a range where the produced polyamic acid does not precipitate. In addition, since water in the solvent inhibits the polymerization reaction and causes hydrolysis of the resulting polyamic acid, it is preferable to use a solvent that has been dehydrated and dried.

The concentration of the polyamic acid is preferably 1 to 30% by mass, more preferably 5 to 20% by mass, from the viewpoint that precipitation of a polymer is less likely to occur and a high molecular weight product is easily obtained.

The polyamic acid obtained as described above can be recovered by pouring the reaction solution into a poor solvent while sufficiently stirring the reaction solution to precipitate the polyamic acid. Further, the precipitation is performed several times, and after washing with a poor solvent, drying is performed at normal temperature or under heating, whereby a powder of a purified polyamic acid can be obtained. 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 polyamic acid ester >

The polyamic acid ester can be produced by the method (1), (2), or (3) shown below.

(1) Case of production from Polyamic acid

The polyamic acid ester can be produced by esterifying a polyamic acid obtained from a tetracarboxylic dianhydride and a diamine. Specifically, the polyamic acid can be produced by reacting the 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, 4- (4,6-dimethoxy-1,3,5-triazin-2-yl) -4-methylmorpholine chloride, and the like. The amount of the esterifying agent to be used is preferably 2 to 6 molar equivalents relative to 1 mole of the repeating unit.

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 of these may be used or 2 or more of these 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 that precipitation of a polymer is less likely to occur and a high molecular weight product is easily obtained.

(2) Produced by reacting 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 reaction can be carried out by reacting a tetracarboxylic acid diester dichloride and 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 to 4 hours.

Pyridine, triethylamine, 4-dimethylaminopyridine and the like can be used as the base, but pyridine is preferable because the reaction proceeds mildly. The amount of the base to be used is preferably 2 to 4 times by mol based on the tetracarboxylic acid diester dichloride, 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, and 1 or more thereof may be used or 2 or more thereof may be used in combination, from the viewpoint of solubility of the monomer and the polymer. The polymer concentration during production is preferably 1 to 30% by mass, more preferably 5 to 20% by mass, from the viewpoint of being less likely to cause precipitation of the polymer and easily obtaining a high molecular weight product. In addition, in order to prevent hydrolysis of the tetracarboxylic acid diester dichloride, the solvent used for producing the polyamic acid ester is preferably dehydrated as much as possible, and external air is preferably prevented from being mixed in a nitrogen atmosphere.

(3) From tetracarboxylic diesters and diamines

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 the tetracarboxylic acid diester and the 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-triazinyl-methylmorpholine, 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) phosphonic acid, etc. can be used. The amount of the condensing agent to be used is preferably 2 to 3 times by mol based on the tetracarboxylic 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 based on the diamine component, from the viewpoint of ease of removal and availability of a high molecular weight material.

In addition, in the above reaction, the reaction is efficiently carried out by adding a lewis acid. 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 time mole based on the diamine component.

Among the above-mentioned 3 methods for producing polyamic acid esters, the above-mentioned method (1) or the above-mentioned method (2) is particularly preferable because a polyamic acid ester having a high molecular weight can be obtained.

The solution of the polyamic acid ester obtained as described above can be poured into a poor solvent while sufficiently stirring the solution to precipitate a polymer. The precipitation was carried out several times, and after washing with a poor solvent, drying was carried out at normal 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 as the component (a) can be produced by imidizing the polyamic acid or polyamic acid ester. In the case of producing a polyimide from a polyamic acid ester, chemical imidization by adding a basic catalyst to the polyamic acid ester solution or to a polyamic acid solution obtained by dissolving a polyamic acid ester resin powder in an organic solvent is simple. Chemical imidization is preferable because imidization reaction proceeds at a relatively low temperature and a decrease in molecular weight of the polymer does not easily occur during imidization.

The chemical imidization may be performed by stirring the polyamic acid or polyamic acid ester to be imidized in an organic solvent in the presence of a basic catalyst. As the organic solvent, a solvent used in the above-mentioned polymerization reaction can be used. Examples of the basic catalyst include: pyridine, triethylamine, trimethylamine, tributylamine, trioctylamine, and the like. Among them, triethylamine is preferred because it has a sufficient basicity to allow the reaction to proceed.

The temperature for the imidization is-20 to 140 ℃, preferably 0 to 100 ℃, and the reaction time may be 1 to 100 hours. The amount of the basic catalyst is 0.5 to 30 times, preferably 2 to 20 times, by mole the polyamic acid or amic acid ester group. The imidization rate of the resulting polymer can be controlled by adjusting the amount of catalyst, temperature, reaction time. Since the added catalyst and the like remain in the solution after the imidization reaction, it is preferable to recover the obtained imidized polymer and redissolve it in an organic solvent to prepare a liquid crystal aligning agent.

The polymer can be precipitated by pouring the solution of the polyimide obtained as described above into a poor solvent while sufficiently stirring the solution. The precipitation is carried out several times, and after washing with a poor solvent, drying is carried out at normal temperature or under heating, whereby a purified polyamic acid ester powder can be obtained.

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.

The polyimide as the component (a) contained in the liquid crystal aligning agent of the present invention can be obtained by imidizing a polyimide precursor as described above, and the imidization ratio in this case needs to be 20 to 80%. When the imidization ratio is too large, the film-coating property is remarkably lowered, while when the imidization ratio is too small, the hardness of the obtained liquid crystal alignment film may not be sufficiently obtained. Among them, the imidization ratio is more preferably 50 to 70%.

The molecular weight of the polyimide is preferably 2000 to 500000, more preferably 5000 to 300000, and further preferably 10000 to 100000 in terms of weight average molecular weight (Mw). The number average molecular weight (Mn) is preferably 1000 to 250000, more preferably 2500 to 150000, and still more preferably 5000 to 50000.

< ingredient (B) >

The component (B) contained in the liquid crystal aligning agent of the present invention is a compound having 2 or more crosslinkable functional groups. From the viewpoint of availability and effect, such crosslinkable functional group is preferably at least 1 selected from the group consisting of a hydroxyl group, a (meth) acrylate group, a blocked isocyanate group, an oxetanyl group, and an epoxy group. Among them, hydroxyl group is preferable. The compound as the component (B) may have 2 or more of the same crosslinkable functional groups, or may have 2 or more of different crosslinkable functional groups of 2 or more. The number of crosslinkable functional groups is not limited to an upper limit, but is usually 8 or less, preferably 6 or less.

In particular, a compound represented by the following formula (2) is a preferable compound having 2 or more hydroxyl groups.

In the above formula (2), X ₂ Is an aliphatic hydrocarbon group having 1 to 20 carbon atoms or an n-valent organic group containing an aromatic hydrocarbon group. n is an integer of 2 to 6. Any carbon of the aliphatic hydrocarbon group or aromatic hydrocarbon group is optionally replaced by nitrogen or oxygen.

R ₂ And R ₃ Each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms and optionally having a substituent, an alkenyl group having 2 to 4 carbon atoms and optionally having a substituent, or an alkynyl group having 2 to 4 carbon atoms and optionally having a substituent. In addition, R ₂ And R ₃ At least one of them represents a hydrocarbon group substituted with a hydroxyl group.

Wherein X in the formula (2) is X in terms of liquid crystal alignment ₂ The atom bonded directly to the carbonyl group is preferablyCarbon atoms not forming aromatic rings. In addition, from the viewpoint of liquid crystal alignment and solubility, X of formula (2) ₂ Preferably an aliphatic hydrocarbon group, more preferably having 1 to 10 carbon atoms. In the formula (2), n is preferably 2 to 4 from the viewpoint of solubility.

In the formula (2), R is from the viewpoint of reactivity ₂ And R ₃ At least one of them is preferably a structure represented by the following formula (3), and more preferably a structure represented by the following formula (4).

In the formula (3), R ₄ ～R ₇ Each independently a hydrogen atom, a hydrocarbyl group, or a hydrocarbyl group substituted with a hydroxyl group.

Preferred examples of the compound having 2 or more hydroxyl-containing groups include the following.

(B) When the amount of the component is too large, the liquid crystal alignment property and the pretilt angle are affected; if too small, the effects of the present invention cannot be obtained. Therefore, the content of the component (B) is preferably 0.1 to 20% by mass, more preferably 1 to 10% by mass, based on the component (a).

< ingredient (C) >

The liquid crystal aligning agent of the present invention may further contain, as the component (C), a polyimide precursor which is a reaction product of a tetracarboxylic acid derivative component and a diamine component.

As the polyimide precursor of the component (C), the tetracarboxylic acid derivative and diamine described as the raw materials of the polyimide precursor which is a precursor of the polyimide of the component (a) can be used, except for the polyimide precursor which is the same as the polyimide precursor of the component (a) contained in the same liquid crystal aligning agent. As the polyimide precursor, polyamic acid is preferable.

The liquid crystal aligning agent of the present invention can further improve the film strength of the liquid crystal alignment film obtained by containing the component (C). The component (C) in the liquid crystal aligning agent is preferably 20 to 80 mol%, more preferably 40 to 70 mol%, based on the component (a).

< liquid Crystal alignment agent >

The liquid crystal aligning agent of the present invention has a form of a solution obtained by dissolving the components (a) and (B) and, if necessary, the component (C) in an organic solvent.

The concentration of the polymer in the liquid crystal aligning agent of the present invention may be appropriately changed depending on the thickness of a coating film to be formed, but is preferably 1 mass% or more from the viewpoint of forming a uniform coating film having no defects; from the viewpoint of storage stability of the solution, it is preferably set to 10% by mass or less. Particularly preferably 3 to 6.5 mass%.

The organic solvent contained in the liquid crystal aligning agent of the present invention is not particularly limited as long as it can uniformly dissolve the contained polymer.

Examples thereof include: n, N-dimethylformamide, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, dimethyl sulfoxide, γ -butyrolactone, 1,3-dimethyl-imidazolidinone, methyl ethyl ketone, cyclohexanone, cyclopentanone, 4-hydroxy-4-methyl-2-pentanone, and the like. In particular, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone or γ -butyrolactone is preferably used.

Among the organic solvents contained in the liquid crystal aligning agent of the present invention, the 1 st solvent (I) and the 2 nd solvent (II) are preferably contained, and the 1 st solvent (I) contains at least 1 selected from the group consisting of N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-pentyl-2-pyrrolidone, γ -butyrolactone, γ -valerolactone, 1,3-dimethyl-2-imidazolidinone, 3-methoxy-N, N-dimethylpropionamide, and 3-butoxy-N, N-dimethylpropionamide,

the 2 nd solvent (II) comprises at least 1 selected from the group consisting of butyl cellosolve, butyl cellosolve acetate, 1-butoxy-2-propanol, 2-butoxy-1-propanol, dipropylene glycol dimethyl ether, dipropylene glycol monomethyl ether, diacetone alcohol, diisobutyl carbinol, diisobutyl ketone, propylene carbonate, propylene glycol diacetate, and diisoamyl ether.

Further, when the polymer of the present invention has high solubility in a solvent, it is preferable to use a solvent represented by the above-mentioned formulae [ D-1] to [ D-3 ].

The organic solvent in the liquid crystal aligning agent of the present invention is preferably 20 to 99% by mass of the entire solvent contained in the liquid crystal aligning agent. Among them, 20 to 90% by mass is preferable. More preferably 30 to 80 mass%.

The liquid crystal aligning agent of the present invention may be a solvent (also referred to as a poor solvent) that improves the film coatability and surface smoothness of a liquid crystal alignment film when the liquid crystal aligning agent is applied. Specific examples of the poor solvent are listed below, but not limited to these examples.

Examples thereof include: ethanol, isopropanol, 1-butanol, 2-butanol, isobutanol, tert-butanol, 1-pentanol, 2-pentanol, 3-pentanol, 2-methyl-1-butanol, isopentanol, tert-pentanol, 3-methyl-2-butanol, neopentyl alcohol, 1-hexanol, 2-methyl-1-pentanol, 2-methyl-2-pentanol, 2-ethyl-1-butanol, 1-heptanol, 2-heptanol, 3-heptanol, 1-octanol, 2-ethyl-1-hexanol, cyclohexanol, 1-methylcyclohexanol, 2-methylcyclohexanol, 3-methylcyclohexanol, 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 3265 zxft-butanediol, 1,4-butanediol, 3-methyl-cyclohexanol, 4232-butanediol, and mixtures thereof 2,3-butanediol, 1,5-pentanediol, 2-methyl-2,4-pentanediol, 2-ethyl-1,3-hexanediol, dipropyl ether, dibutyl ether, dihexyl ether, dioxane, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, 1,2-butoxyethane, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol methyl ethyl ether, diethylene glycol dibutyl ether, 2-pentanone, 3-pentanone, 2-hexanone, 2-heptanone, 4-heptanone, 3-ethoxybutyl acetate, 1-methylpentyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, ethylene glycol monoacetate, ethylene glycol diacetate, propylene carbonate, propylene glycol diacetate, 2-heptanone, 4-ethoxybutyl acetate, 1-methylpentyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, ethylene glycol monoacetate, ethylene glycol diacetate, propylene carbonate, and mixtures thereof, ethylene carbonate, 2- (methoxymethoxy) ethanol, ethylene glycol monobutyl ether, ethylene glycol monoisoamyl ether, ethylene glycol monohexyl ether, 2- (hexyloxy) ethanol, furfuryl alcohol, diethylene glycol, propylene glycol monobutyl ether, 1- (butoxyethoxy) propanol, propylene glycol monomethyl ether acetate, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol dimethyl ether, tripropylene glycol monomethyl ether, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, ethylene glycol monoacetate, ethylene glycol diacetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, 2- (2-ethoxyethoxy) ethyl acetate, diethylene glycol acetate, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, n-butyl acetate, propylene glycol monoethyl ether acetate, methyl pyruvate, ethyl pyruvate, methyl 3-methoxypropionate, methyl 3-ethoxypropionate, ethyl 3-methoxypropionate, propyl 3-methoxypropionate, butyl lactate, methyl lactate, ethyl lactate, n-butyl lactate, isoamyl lactate, and the solvent represented by the formula 1-D.

Of these, 1-hexanol, cyclohexanol, 1,2-ethylene glycol, 1,2-propylene glycol, propylene glycol monobutyl ether, ethylene glycol monobutyl ether, or dipropylene glycol dimethyl ether are preferred.

The poor solvent is preferably 1 to 80% by mass, more preferably 10 to 80% by mass, and still more preferably 20 to 70% by mass of the entire solvent contained in the liquid crystal aligning agent.

In addition to the above, the liquid crystal aligning agent of the present invention may further comprise: polymers other than the polymers described herein; a dielectric or conductive substance for changing electric characteristics such as a dielectric constant and conductivity of the liquid crystal alignment film; a silane coupling agent for improving the adhesion between the liquid crystal alignment film and the substrate; a crosslinkable compound for improving the hardness and the density of the film when the liquid crystal alignment film is produced; and an imidization accelerator for effectively accelerating imidization by heating the polyimide precursor when the coating film is fired.

< liquid Crystal alignment film >

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

Examples of the method for applying the liquid crystal aligning agent of the present invention include spin coating, printing, and ink jet. In the drying and firing steps after the liquid crystal aligning agent of the present invention is applied, any temperature and time can be selected. In general, in order to sufficiently remove the solvent contained, the resultant is dried at 50 to 120 ℃ and preferably 60 to 100 ℃ for 1 to 10 minutes, preferably 2 to 5 minutes, and then fired at 150 to 300 ℃ and preferably 200 to 240 ℃ for 5 to 120 minutes, preferably 10 to 30 minutes. The thickness of the coating film after firing is not particularly limited, but if it is too thin, the reliability of the liquid crystal display element may be lowered, and therefore, it is 5 to 300nm, preferably 10 to 200nm.

Examples of the method for aligning the liquid crystal alignment film include brushing and photo-alignment treatment.

The brushing process can be performed using an existing brushing apparatus. Examples of the material of the brush polishing cloth in this case include: cotton, nylon, rayon, and the like. As the conditions for the brushing treatment, the following conditions are generally used: a rotation speed of 300 to 2000rpm, a feed speed of 5 to 100mm/s, and a pressing amount of 0.1 to 1.0 mm. Thereafter, the residue generated by the brushing is removed by ultrasonic washing using pure water, alcohol, or the like.

Specific examples of the photo-alignment treatment method include the following methods: the surface of the coating film is irradiated with a radiation beam deflected in a predetermined direction, and in some cases, the surface is further subjected to a heat treatment at a temperature of 150 to 250 ℃ to impart a liquid crystal aligning ability. As the radiation rays, ultraviolet rays and visible rays having a wavelength of 100 to 800nm can be used. Among them, ultraviolet rays having a wavelength of 100 to 400nm are preferable, and ultraviolet rays having a wavelength of 200 to 400nm are particularly preferable. In addition, in order to improve the liquid crystal alignment property, the coating substrate may be heated at 50 to 250 ℃ and irradiated with radiation. The irradiation amount of the radiation is preferably 1 to 10000mJ/cm ² Particularly preferably 100 to 5000mJ/cm ² . The liquid crystal alignment film prepared as described above can stably align liquid crystal molecules in a certain direction.

The higher the extinction ratio of polarized ultraviolet light, the higher the anisotropy that can be imparted, and therefore, the higher the extinction ratio. Specifically, the extinction ratio of the linearly polarized ultraviolet ray is preferably 10:1 or more, more preferably 20:1 or more.

Then, the above-mentioned polarized radiation irradiated film may be subjected to a contact treatment with a solvent containing at least 1 selected from the group consisting of water and an organic solvent.

The solvent used for the contact treatment is not particularly limited as long as it dissolves the decomposition product generated by the 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, cyclohexyl acetate, and the like. These solvents may be used in combination of 2 or more.

From the viewpoint of versatility and safety, at least 1 selected from the group consisting of water, 2-propanol, 1-methoxy-2-propanol, and ethyl lactate is more preferable. Water, 2-propanol, or a mixed solvent of water and 2-propanol is particularly preferable.

In the present invention, the contact treatment of the film irradiated with polarized radiation and the solution containing the solvent is carried out by a method in which the film and the solution are preferably brought into sufficient contact, such as immersion treatment or spray (spray) treatment. Among them, a method of immersion treatment in a solution containing a solvent is preferable, and 10 seconds to 1 hour is preferable, and 1 to 30 minutes is more preferable. The contact treatment may be carried out at normal temperature or under heating, and is preferably carried out at 10 to 80 ℃ and more preferably at 20 to 50 ℃. If necessary, means for improving the contact such as ultrasonic waves may be applied.

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

Further, in order to dry the solvent and reorient molecular chains in the film, the film subjected to the contact treatment with the solution containing the solvent may be heated at a temperature of 150 ℃ or higher.

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

When the heating time is too short, the effect of reorienting the molecular chains may not be obtained, and when the heating time is too long, the molecular chains may be decomposed, and therefore, 10 seconds to 30 minutes is preferable, and 1 to 10 minutes is more preferable.

< liquid Crystal display element >

The liquid crystal display element of the present invention is characterized by comprising the liquid crystal alignment film of the present invention. The liquid crystal display element of the present invention is as follows: after a substrate with a liquid crystal alignment film is obtained from the liquid crystal alignment agent of the present invention by the above-described method for producing a liquid crystal alignment film, a liquid crystal cell is produced by a known method, and a liquid crystal display element is produced using the liquid crystal cell.

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.

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 made of, for example, ITO electrodes, and patterned (Patterning) in order to enable desired image display. Then, an insulating film is provided on each substrate to cover the common electrode and the segment electrode. The insulating film canTo form a film containing SiO by a sol-gel method ₂ -TiO ₂ The film of (4).

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

Next, a liquid crystal material was injected into a space surrounded by the 2 substrates and the sealing material through an opening portion provided in the sealing material. Thereafter, the opening is sealed with an adhesive. For the injection, a vacuum injection method may be used, or a method using a capillary phenomenon in the atmosphere may be used. Next, a polarizing plate is disposed. Specifically, a pair of polarizing plates are attached to the surfaces of the 2 substrates opposite to the liquid crystal layer. The liquid crystal display element of the present invention is obtained by the above-described steps.

In the present invention, as the sealing agent, for example, a resin having a reactive group such as an epoxy group, an acryloyl group, a (meth) acryloyl group, a hydroxyl group, an allyl group, or an acetyl group, which is cured by irradiation with ultraviolet light or heating is used. In particular, curable resins having both an epoxy group and a (meth) acryloyl group are preferably used.

The sealant of the present invention may contain an inorganic filler for the purpose of improving adhesiveness and moisture resistance. The inorganic filler that can be used is not particularly limited, and specific examples thereof include: spherical silica, fused silica, crystalline silica, titanium oxide, titanium black, silicon carbide, silicon nitride, boron nitride, calcium carbonate, magnesium carbonate, barium sulfate, calcium sulfate, mica, talc, clay, alumina, magnesium oxide, zirconium oxide, aluminum hydroxide, calcium silicate, aluminum silicate, lithium aluminum silicate, zirconium silicate, barium titanate, glass fiber, carbon fiber, molybdenum disulfide, asbestos, and the like. Preferably, there may be mentioned: spherical silica, fused silica, crystalline silica, titanium oxide, titanium black, silicon nitride, boron nitride, calcium carbonate, barium sulfate, calcium sulfate, mica, talc, clay, alumina, aluminum hydroxide, calcium silicate, or aluminum silicate. The inorganic filler may be used in a mixture of 2 or more.

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 and the methods for measuring the respective properties are as follows.

NMP: n-methyl-2-pyrrolidone, GBL: gamma-butyrolactone,

BCS: butyl cellosolve,

DA-1: bis (4-aminophenoxy) methane,

DA-2:1,2-bis (4-aminophenoxy) ethane,

DA-3: N-tert-butoxycarbonyl-N- (2- (4-aminophenyl) ethyl) -N- (4-aminobenzyl) amine,

DA-4: see the following formula (DA-4),

DA-5: 2-t-Butoxycarbonylaminomethyl-p-phenylenediamine (wherein Boc represents a t-butoxycarbonyl group),

DA-6: see the following formula (DA-6),

CA-1: see the following formulae (CA-1), CA-2: see the following formula (CA-2),

CA-3: see the following formulae (CA-3), AD-1: see the following formula (AD-1)

[ viscosity ]

The viscosity of the solution was measured using an E-type viscometer TVE-22H (manufactured by Toyobo Co., ltd.) at a sample volume of 1.1mL, a conical rotor TE-1 (1 ℃ C., 34' R24) and a temperature of 25 ℃.

[ molecular weight ]

The molecular weight was measured by a GPC (normal temperature gel permeation chromatography) apparatus, and the number average molecular weight (Mn) and the weight average molecular weight (Mw) were calculated as values converted from polyethylene glycol and polyethylene oxide.

GPC apparatus: shodex (GPC-101), column: shodex (series of KD803 and KD 805), column temperature: 50 ℃ and eluent: n, N-dimethylformamide (as additive, lithium bromide-water (LiBr. H) ₂ O) 30 mmol/L, anhydrous phosphoric acid crystals (orthophosphoric acid) 30 mmol/L, tetrahydrofuran (THF) 10 ml/L), flow rate: 1.0 ml/min

Reference samples for preparing the standard curve: TSK standard polyethylene oxide (weight average molecular weight (Mw) of about 900000, 150000, 100000, 30000) manufactured by east Cao She, and polyethylene glycol (peak top molecular weight (Mp) of about 12000, 4000, 1000) manufactured by Polymer Laboratories Ltd. In order to avoid overlapping of peaks in the measurement, samples in which 4 kinds of samples including 900000, 100000, 12000, and 1000 were mixed and samples in which 3 kinds of samples including 150000, 30000, and 4000 were mixed were measured.

< measurement of imidization Rate >

20mg of the polyimide powder was put into an NMR sample tube (. Phi.5 (manufactured by Softgrass scientific Co.), 0.53ml of deuterated dimethyl sulfoxide (DMSO-d 6,0.05% TMS (tetramethylsilane) mixture) was added thereto, and the mixture was dissolved completely by applying ultrasonic waves. For this solution, proton NMR at 500MHz was measured by an NMR measuring machine (JNW-ECA 500) (manufactured by JEOL DATUM LTD.). The imidization ratio was determined as follows: the proton derived from the structure which did not change before and after imidization was identified as a reference proton, and the peak cumulative value of this proton and the peak cumulative value of the proton derived from the NH group of amic acid appearing in the vicinity of 9.5ppm to 10.0ppm were used to obtain the following formula.

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

In the above formula, x represents a peak accumulation value of a proton derived from an NH group of amic acid, y represents a peak accumulation value of a reference proton, and α represents a ratio of the number of protons of the reference proton to 1 NH group of amic acid (imidization ratio of 0%).

[ preparation of liquid Crystal cell ]

A liquid crystal cell having a structure of a liquid crystal display element of Fringe Field Switching (FFS) system was prepared.

First, a substrate with electrodes is prepared. The substrate was a glass substrate having a size of 30mm × 50mm and a thickness of 0.7 mm. An ITO electrode having a solid pattern, which is a counter electrode constituting the 1 st layer, is formed on the substrate. A SiN (silicon nitride) film formed by a CVD method as a 2 nd layer was formed on the counter electrode of the 1 st layer. The SiN film of the 2 nd layer has a film thickness of 500nm and functions as an interlayer insulating film. A comb-shaped pixel electrode formed by patterning an ITO film as a 3 rd layer is disposed on the SiN film of the 2 nd layer, and two pixels, i.e., a 1 st pixel and a 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 3 rd layer has a comb-teeth shape formed by arranging a plurality of electrode elements having a shape of "く" with a curved central portion. 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 electrode elements in the shape of "く" bent at the central portion, the shape of each pixel is not rectangular, but has a shape similar to a bold shape of "く" bent at the central portion like the electrode elements. Each pixel is divided into upper and lower regions with a curved portion at the center as a boundary, and has a 1 st region on the upper side and a 2 nd region on the lower side of the curved portion.

When the 1 st region and the 2 nd region of each pixel are compared, the directions of formation of the electrode elements constituting the pixel electrodes are different. That is, when the brushing direction of the liquid crystal alignment film described later is set as a reference, the 1 st region of the pixel is formed so that the electrode element of the pixel electrode is at an angle of +10 ° (clockwise), and the 2 nd region of the pixel is formed so that the electrode element of the pixel electrode is at an angle of-10 ° (clockwise). That is, the 1 st region and the 2 nd region of each pixel are configured such that the directions of the rotational motion (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 directions to each other.

Next, the liquid crystal aligning agent was filtered through a filter having a pore size of 1.0 μm, and then applied by spin coating onto the prepared substrate with electrodes and the glass substrate having an ITO film formed on the back surface and a columnar spacer having a height of 4 μm. After drying on a hot plate at 80 ℃ for 5 minutes, the resultant was baked in a hot air circulating oven at 230 ℃ for 20 minutes to form a coating film having a thickness of 100 nm. The film surface was irradiated with a polarizing plate to have an extinction ratio of 10:1 or more linearly polarized ultraviolet rays having a wavelength of 254 nm. The substrate was immersed in at least one solvent selected from water and organic solvents for 3 minutes, then immersed in pure water for 1 minute, and heated on a hot plate at 150 to 300 ℃ for 5 minutes to obtain a substrate with a liquid crystal alignment film. The above 2 substrates were set as 1 group, a sealant was printed on the substrates, another substrate was attached so that the liquid crystal alignment film surfaces were opposed to each other and the alignment direction was 0 °, and then the sealant was cured to prepare an empty cell. Liquid crystal MLC-3019 (manufactured by Merck & co.) was injected into the empty cell by a reduced pressure injection method, and the injection port was sealed, thereby obtaining an FFS-driven liquid crystal cell. Thereafter, the obtained liquid crystal cell was heated at 110 ℃ for 1 hour, and left overnight for each evaluation.

[ evaluation of afterimages by Long-term AC drive ]

A liquid crystal cell having the same structure as the liquid crystal cell used for the evaluation of the afterimage was prepared.

Using this liquid crystal cell, an AC voltage of. + -. 5V was applied at a frequency of 60Hz for 120 hours in a constant temperature environment of 60 ℃. After that, the pixel electrode and the counter electrode of the liquid crystal cell were short-circuited, and left at room temperature for one day in this state.

After the placement, the liquid crystal cell was set between 2 sheets of polarizing plates arranged so that the polarizing axes were orthogonal, and the backlight was turned on in advance in a state where no voltage was applied, and the arrangement angle of the liquid crystal cell was adjusted so that the brightness of transmitted light was minimized. Then, the rotation angle at which the liquid crystal cell is rotated from the angle at which the 2 nd area of the 1 st pixel becomes darkest to the angle at which the 1 st area becomes darkest is calculated as the angle Δ. Similarly, in the 2 nd pixel, the 2 nd region and the 1 st region are compared, and the same angle Δ is calculated.

[ evaluation of Pencil hardness ]

Samples for evaluation of pencil hardness were produced as follows. The liquid crystal alignment agent was coated on a 30mm × 40mm ITO substrate by spin coating. After drying on a hot plate at 80 ℃ for 2 minutes, the film was baked in a hot air circulation oven at 230 ℃ for 14 minutes to form a coating film having a thickness of 100 nm. The coated surface is subjected to alignment treatment such as brushing and polarized ultraviolet irradiation to obtain a substrate with a liquid crystal alignment film. The substrate was immersed in at least one solvent selected from water and organic solvents for 3 minutes, then immersed in pure water for 1 minute, and heated on a hot plate at 150 to 300 ℃ for 14 minutes to obtain a substrate with a liquid crystal alignment film. The liquid crystal alignment film surface of the substrate was measured by the pencil hardness test method (JIS K5400).

< Synthesis example 1>

In a 100mL four-necked flask equipped with a stirrer and a nitrogen introduction tube, 1.75g (7.60 mmol) of DA-1, 4.64g (19.0 mmol) of DA-3.89g (11.4 mmol) of DA-were weighed, 46.9g of NMP was added, and the mixture was stirred and dissolved while feeding nitrogen. While stirring the diamine solution, CA-1.93g (35.3 mmol) and NMP 36.1g were added to adjust the solid content to 18% by mass, and the mixture was stirred at 40 ℃ for 24 hours to obtain a polyamic acid solution (A) (viscosity: 800 mPas). Mn =10800, mw =23600 of polyamic acid.

30g of the obtained polyamic acid solution was weighed in a 100ml four-necked flask equipped with a stirrer and a nitrogen introduction tube, 37.5g of NMP was added thereto, and the mixture was stirred for 30 minutes. To the obtained polyamic acid solution were added 3.39g of acetic anhydride and 0.88g of pyridine, and the mixture was heated at 55 ℃ for 3 hours to effect chemical imidization. The resulting reaction solution was poured into 270ml of methanol while stirring, and the precipitated precipitate was collected by filtration and washed 3 times with 270ml of methanol. The obtained resin powder was dried at 60 ℃ for 12 hours to obtain a polyimide resin powder (A).

The polyimide resin powder had an imidization rate of 67%, mn =7500, mw =1100.

< Synthesis example 2>

In a 100mL four-necked flask equipped with a stirrer and a nitrogen inlet, 1.50g (15.2 mmol) of DA-1, 2.78g (11.4 mmol) of DA-2, 3.89g (11.4 mmol) of DA-3 were weighed, and NMP 46.36g was added and stirred and dissolved while feeding nitrogen. While stirring the diamine solution, CA-1.92g (35.3 mmol) was added, and further NMP 36.1g was added to adjust the solid content concentration to 18% by mass, and the mixture was stirred at 40 ℃ for 24 hours to obtain a polyamic acid solution (C) (viscosity: 820 mPas). The Mn =11000 and Mw =25200 of the polyamic acid.

30g of the obtained polyamic acid solution was weighed into a 100mL four-necked flask equipped with a stirrer and a nitrogen introduction tube, 37.5g of NMP was added thereto, and the mixture was stirred for 30 minutes. To the obtained polyamic acid solution were added 3.40g of acetic anhydride and 0.88g of pyridine, and the mixture was heated at 55 ℃ for 3 hours to effect chemical imidization. The resulting reaction solution was poured into 270ml of methanol while stirring, and the precipitated precipitate was collected by filtration and washed 3 times with 270ml of methanol. The obtained resin powder was dried at 60 ℃ for 12 hours to obtain a polyimide resin powder (B).

The polyimide resin powder had an imidization ratio of 67%, mn =8000, mw =12500.

< Synthesis example 3>

In a50 mL four-necked flask equipped with a stirrer and a nitrogen inlet, 0.69g (3.00 mmol) of DA-1.60g (5.00 mmol) and 0.68g (2.00 mmol) of DA-3 were weighed, 32.3g of NMP was added thereto, and the mixture was stirred and dissolved while feeding nitrogen. While stirring the diamine solution, CA-1.17g (9.70 mmol) and NMP 5.00g were added to adjust the solid content to 18% by mass, and the mixture was stirred at 40 ℃ for 24 hours to obtain a polyamic acid solution (C) (viscosity: 790 mPas). Mn =15500, mw =40600 of the polyamic acid.

50g of the obtained polyamic acid solution was weighed into a 100mL four-necked flask equipped with a stirrer and a nitrogen introduction tube, and 62.5g of NMP was added thereto and stirred for 30 minutes. To the obtained polyamic acid solution were added 5.39g of acetic anhydride and 1.39g of pyridine, and the mixture was heated at 55 ℃ for 3 hours to effect chemical imidization. The resulting reaction solution was poured into 525ml of methanol while stirring, and the precipitated precipitate was collected by filtration and washed 3 times with 525ml of methanol. The obtained resin powder was dried at 60 ℃ for 12 hours to obtain a polyimide resin powder (C).

The polyimide resin powder had an imidization ratio of 63%, mn =6000, and mw =9600.

< Synthesis example 4>

In a 100mL four-necked flask equipped with a stirrer and a nitrogen inlet, 6.91g (30.0 mmol) of DA-1 was weighed, 59.1g of NMP was added, and the mixture was stirred and dissolved while feeding nitrogen. While stirring the diamine solution, 1.50g (6.00 mmol) of CA-3 was added, and after stirring at room temperature for 3 hours, 6.62g (22.5 mmol) of CA-2 was added, and NMP 12.8gg was added to adjust the solid content to 15 mass%, and the mixture was stirred at room temperature for 24 hours to obtain a polyamic acid solution (D) (viscosity: 870 mPas). Mn =13200, mw =35700 of polyamic acid.

< Synthesis example 5>

In a 100mL four-necked flask equipped with a stirrer and a nitrogen inlet, 6.33g (25.9 mmol) of DA-2 and 3.79g (11.1 mmol) of DA-3 were weighed, 73.1g of NMP was added, and the mixture was stirred and dissolved while feeding nitrogen. While stirring the diamine solution, CA-1.73g (34.4 mmol) and NMP 8.12g were added to adjust the solid content to 18% by mass, and the mixture was stirred at 40 ℃ for 24 hours to obtain a polyamic acid solution (E) (viscosity: 800 mPas). Mn =13500, mw =23600 of polyamic acid.

30g of the obtained polyamic acid solution was weighed into a 100mL four-necked flask equipped with a stirrer and a nitrogen introduction tube, and 15.0g of NMP was added thereto and stirred for 30 minutes. To the obtained polyamic acid solution were added 3.37g of acetic anhydride and 0.44g of pyridine, and the mixture was heated at 55 ℃ for 3 hours to effect chemical imidization. The resulting reaction solution was poured into 212ml of methanol while stirring, and the precipitated precipitate was collected by filtration and washed 3 times with 212ml of methanol. The obtained resin powder was dried at 60 ℃ for 12 hours to obtain a polyimide resin powder (F). The imidization ratio of the polyimide resin was 68%, mn =9400, mw =23000.

< Synthesis example 6>

In a 100mL four-necked flask equipped with a stirrer and a nitrogen inlet, 4.40g (18.0 mmol) of DA-2 and 6.15g (18.0 mmol) of DA-3 were weighed, 74.0g of NMP was added, and the mixture was stirred and dissolved while feeding nitrogen. While stirring the diamine solution, CA-1.50g (33.4 mmol) and NMP 8.22G were added to adjust the solid content to 18% by mass, and the mixture was stirred at 40 ℃ for 24 hours to obtain a polyamic acid solution (G) (viscosity: 820 mPas). The Mn =11000 and mw =30700 of the polyamic acid.

20g of the obtained polyamic acid solution (A) was weighed into a 100mL four-necked flask equipped with a stirrer and a nitrogen introduction tube, 14.29g of NMP was added thereto, and the mixture was stirred for 30 minutes. To the obtained polyamic acid solution were added 1.48g of acetic anhydride and 0.38g of pyridine, and the mixture was heated at 60 ℃ for 3 hours to effect chemical imidization. The resulting reaction solution was poured into 150ml of methanol while stirring, and the precipitated precipitate was collected by filtration and washed 3 times with 150ml of methanol. The obtained resin powder was dried at 60 ℃ for 12 hours to obtain a polyimide resin powder (H). The polyimide resin powder had an imidization ratio of 70%, mn =9050, mw =16600.

< example 1>

In a 100ml Erlenmeyer flask, 1.80g of the polyimide resin powder (A) obtained in Synthesis example 1 was taken, 10.2g of NMP was added to adjust the solid content to 15%, and the mixture was stirred at 70 ℃ for 24 hours to dissolve the powder, thereby obtaining a polyimide solution (K). To the polyimide solution, 0.09g of AD-1, 11.9g of NMP and 6.00g of BCS were added, and the mixture was stirred at room temperature for 3 hours to obtain a liquid crystal aligning agent (1). The liquid crystal aligning agent was confirmed to be a homogeneous solution without any abnormality such as clouding and precipitation.

< example 2>

1.80g of the polyimide resin powder (B) obtained in Synthesis example 2 was taken in a 100ml Erlenmeyer flask, 10.2g of NMP was added to adjust the solid content to 15%, and the mixture was stirred at 70 ℃ for 24 hours to dissolve it, thereby obtaining a polyimide solution (L). To the polyimide solution were added AD-1.09g, NMP 11.9g and BCS 6.00g, and the mixture was stirred at room temperature for 3 hours to obtain a liquid crystal aligning agent (2). The liquid crystal aligning agent was confirmed to be a homogeneous solution without any abnormality such as clouding and precipitation.

< example 3>

1.80g of the polyimide resin powder (C) obtained in Synthesis example 2 was taken in a 100ml Erlenmeyer flask, 22.11g of NMP was added to adjust the solid content to 15%, and the mixture was stirred at 70 ℃ for 24 hours to dissolve the powder, thereby obtaining a polyimide solution (M). To the polyimide solution, 0.09g of AD-1, 11.9g of NMP and 6.00g of BCS were added, and the mixture was stirred at room temperature for 3 hours to obtain a liquid crystal aligning agent (3). The liquid crystal aligning agent was confirmed to be a homogeneous solution without any abnormality such as clouding and precipitation.

< example 4>

In a 100mL Erlenmeyer flask, 7.80g of 18 mass% polyamic acid (D) and 5.20g of 15 mass% polyimide solution (K) were taken, and 0.98g of AD-1, 4.34g of NMP, 5.68g of GBL and 6.00g of BCS were added, followed by stirring at room temperature for 3 hours to obtain a liquid crystal aligning agent (4). The liquid crystal aligning agent was confirmed to be a homogeneous solution without any abnormality such as clouding and precipitation.

< example 5>

In a 100mL Erlenmeyer flask, 7.80g of 18 mass% polyamic acid (D) and 5.20g of 15 mass% polyimide solution (L) were taken, and 0.98g of AD-1, 4.36g of NMP, 5.66g of GBL and 6.00g of BCS were added, followed by stirring at room temperature for 3 hours to obtain a liquid crystal aligning agent (5). The liquid crystal aligning agent was confirmed to be a homogeneous solution without any abnormality such as clouding and precipitation.

< comparative example 1>

1.80g of the polyimide resin powder (F) obtained in Synthesis example 5 was taken in a 100ml Erlenmeyer flask, 10.2g of NMP was added to adjust the solid content to 15%, and the mixture was stirred at 70 ℃ for 24 hours to dissolve it, thereby obtaining a polyimide solution (N). To the polyimide solution, 0.09g of AD-1, 11.9g of NMP and 6.00g of BCS were added, and the mixture was stirred at room temperature for 3 hours to obtain a liquid crystal aligning agent (6). The liquid crystal aligning agent was confirmed to be a homogeneous solution without any abnormality such as clouding and precipitation.

< comparative example 2>

1.80g of the polyimide resin powder (H) obtained in Synthesis example 6 was taken in a 100ml Erlenmeyer flask, 10.2g of NMP was added to adjust the solid content to 15%, and the mixture was stirred at 70 ℃ for 24 hours to dissolve the powder, thereby obtaining a polyimide solution (O). To the polyimide solution, 0.09g of AD-1, 11.9g of NMP and 6.00g of BCS were added, and the mixture was stirred at room temperature for 3 hours to obtain a liquid crystal aligning agent (7). The liquid crystal aligning agent was confirmed to be a homogeneous solution without any abnormality such as clouding and precipitation.

< comparative example 3>

To 12g of the polyimide solution (K) obtained in example 1 were added 12.0g of NMP and 6.00g of BCS, and the mixture was stirred at room temperature for 3 hours to obtain a liquid crystal aligning agent (8). The liquid crystal aligning agent was confirmed to be a homogeneous solution without any abnormality such as clouding and precipitation.

< example 6>

The liquid crystal aligning agent was filtered through a filter having a pore diameter of 1.0 μm, and then applied by spin coating onto the prepared substrate with electrodes and a glass substrate having an ITO film formed on the back surface thereof and having a columnar spacer with a height of 4 μm. After drying on a hot plate at 80 ℃ for 5 minutes, the resultant was baked in a hot air circulating oven at 230 ℃ for 20 minutes to form a coating film having a thickness of 100 nm. The film surface was irradiated with a polarizing plate with an extinction ratio of 26:1 linearly polarized ultraviolet ray of 254nm wavelength of 0.25J/cm ² Then, the substrate was immersed in a mixed solution of pure water 2-propanol =1/1 for 5 minutes, then immersed in pure water for 1 minute, and heated on a hot plate at 230 ℃ for 14 minutes to obtain a substrate with a liquid crystal alignment film. The liquid crystal alignment film surface of the substrate was measured by the pencil hardness test method (JIS K5400) and found to be 3H.

< examples 7 to 10 and comparative examples 4 to 6>

Pencil hardness test samples were each prepared in exactly the same manner as in example 6, except that the liquid crystal aligning agents shown in table 1 were each used instead of the liquid crystal aligning agent (1). The results of evaluation of each pencil hardness test, including the results of example 6, are shown in table 1. In Table 1, "H < "indicates a pencil hardness of less than 1.

[ Table 1]

	Liquid crystal aligning agent	Evaluation of Pencil hardness test
			Example 6	(1)	3H
Example 7	(2)	H
			Example 8	(3)	H
Example 9	(4)	4H
			Example 10	(5)	3H
Comparative example 4	(6)	H＜
			Comparative example 5	(7)	H＜
Comparative example 6	(8)	H＜

< example 12>

The liquid crystal aligning agent (1) obtained in example 1 was filtered through a filter having a pore diameter of 1.0 μm, and then applied by spin coating onto the prepared substrate with electrodes and a glass substrate having an ITO film formed on the back surface thereof and having a columnar spacer with a height of 4 μm. After drying on a hot plate at 80 ℃ for 5 minutes, the resultant was baked in a hot air circulating oven at 230 ℃ for 20 minutes to form a coating film having a thickness of 100 nm. The coated film face was irradiated with an extinction ratio of 26:1 linearly polarized ultraviolet ray of 254nm wavelength of 0.25J/cm ² . The substrate was immersed in pure water for 3 minutes and dried on a hot plate at 230 ℃ for 14 minutes to obtain a substrate with a liquid crystal alignment film.

The obtained 2 substrates were set as 1 group, a sealant was printed on the substrates, another substrate was attached so that the liquid crystal alignment film surfaces were opposed to each other and the alignment direction was 0 °, and then the sealant was cured to prepare an empty cell. Liquid crystal MLC-3019 (manufactured by Merck & co.) was injected into the empty cell by a reduced pressure injection method, and the injection port was sealed, thereby obtaining an FFS-driven liquid crystal cell. Then, the obtained liquid crystal cell was heated at 110 ℃ for 1 hour, left overnight, and subjected to a long-term ac driving for evaluation of the image sticking. The angle Δ of the liquid crystal cell after long-term ac driving was 0.10 degrees.

< examples 12 to 15 and comparative examples 7 to 9>

An FFS-driven liquid crystal cell was prepared in exactly the same manner as in example 11 except that the liquid crystal aligning agents shown in table 2 were respectively used instead of the liquid crystal aligning agent (1) and the irradiation amount of ultraviolet rays was set to the amount shown in table 2, and the afterimage evaluation was performed by long-term ac driving. The values of the angle Δ of the liquid crystal cell after each long-term ac driving are shown in table 2 together with the results of example 11.

[ Table 2]

In industryIs available to

The liquid crystal alignment agent of the present invention can provide a liquid crystal alignment film having high film hardness and good afterimage characteristics. Therefore, the liquid crystal alignment film obtained from the liquid crystal alignment agent of the present invention can provide a liquid crystal display element of IPS drive system or FFS drive system having a high yield in manufacturing a liquid crystal panel and excellent in image sticking characteristics, and can reduce image sticking due to ac drive occurring in the liquid crystal display element of IPS drive system or FFS drive system. Therefore, it can be used in a liquid crystal display element in which high display quality is sought.

The entire contents of the specification, claims, drawings and abstract of japanese patent application No. 2016-225395, filed 2016, 11, 18, are incorporated herein by reference, and the disclosure of the present invention is incorporated herein as a description of the present invention.

Claims

1. A liquid crystal aligning agent comprising the following component (A), component (B) and an organic solvent,

(A) The components: which is a polyimide that is an imide compound of a polyimide precursor that is a reaction product of a tetracarboxylic acid derivative component and a diamine component containing a diamine having a structure of the following formula (1),

wherein, represents a bond with other atom or group;

the tetracarboxylic acid derivative component has at least 1 structure selected from the group consisting of formulas (X1-1) to (X1-10),

in the formulae (X1-1) to (X1-4), R ₃ ～R ₂₃ Are respectively and independently hydrogen atom, halogen atom, carbon number 1EAn alkyl group having 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 which contains a fluorine atom, or a phenyl group;

(B) The components: the compound contains at least 2 crosslinkable functional groups.

2. The liquid crystal aligning agent according to claim 1, wherein the diamine component contains 20 to 50 mol% of a diamine having a structure of formula (1).

3. The liquid crystal aligning agent according to claim 1 or 2, wherein the diamine component further contains a diamine having a structure that is thermally removed to generate an amino group.

4. The liquid crystal aligning agent according to claim 1 or 2, wherein the tetracarboxylic acid derivative component has at least 1 structure selected from the group consisting of,

5. the liquid crystal aligning agent according to claim 1 or 2, wherein the crosslinkable functional group is at least 1 selected from the group consisting of a hydroxyl group-containing group, a (meth) acrylate group, a blocked isocyanate group, an oxetane group, and an epoxy group-containing group.

6. The liquid crystal aligning agent according to claim 1 or 2, wherein the crosslinkable functional group is a hydroxyl group-containing group.

7. The liquid crystal aligning agent according to claim 1 or 2, wherein the compound having 2 or more crosslinkable functional groups is represented by formula (2),

X ₂ is an aliphatic hydrocarbon group having 1 to 20 carbon atoms or an n-valent organic group containing an aromatic hydrocarbon group, n is an integer of 2 to 6, any carbon in the aliphatic hydrocarbon group or the aromatic hydrocarbon group is optionally replaced by nitrogen or oxygen, R ₂ And R ₃ Each independently represents a hydrogen atom, an optionally substituted alkyl group having 1 to 4 carbon atoms, an alkenyl group having 2 to 4 carbon atoms or an alkynyl group having 2 to 4 carbon atoms, R ₂ And R ₃ At least one of them represents a hydrocarbon group substituted with a hydroxyl group.

8. The liquid crystal aligning agent according to claim 7, wherein R in the formula (2) ₂ And R ₃ Is represented by formula (3),

R ₄ ～R ₇ each independently represents a hydrogen atom, a hydrocarbon group, or a hydrocarbon group substituted with a hydroxyl group.

9. The liquid crystal aligning agent according to claim 1 or 2, wherein the compound having 2 or more crosslinkable functional groups is a compound represented by formula (5),

10. the liquid crystal aligning agent according to claim 1 or 2, wherein the component (B) is contained in an amount of 0.1 to 20 mass% based on the component (A).

11. The liquid crystal aligning agent according to claim 1 or 2, further comprising a component (C),

(C) The components: which is a polyimide precursor that is a reaction product of a tetracarboxylic acid derivative component and a diamine component, but does not include the same polyimide precursor as the polyimide precursor of the component (a).

12. The liquid crystal aligning agent according to claim 1 or 2, wherein the organic solvent contains a 1 st solvent (I) and a 2 nd solvent (II), the 1 st solvent (I) comprises at least 1 selected from the group consisting of N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-pentyl-2-pyrrolidone, γ -butyrolactone, γ -valerolactone, 1,3-dimethyl-2-imidazolidinone, 3-methoxy-N, N-dimethylpropionamide, and 3-butoxy-N, N-dimethylpropionamide, and the 2 nd solvent (II) comprises at least 1 selected from the group consisting of butyl cellosolve, butyl cellosolve acetate, 1-butoxy-2-propanol, 2-butoxy-1-propanol, dipropylene glycol dimethyl ether, dipropylene glycol monomethyl ether, diacetone alcohol, diisobutyl methanol, diisobutyl ketone, propylene carbonate, propylene glycol diacetate, diisoamyl ether.

13. A liquid crystal alignment film obtained from the liquid crystal aligning agent according to any one of claims 1 to 12.

14. A method for producing a liquid crystal alignment film, comprising applying the liquid crystal alignment agent according to any one of claims 1 to 12, firing the applied liquid crystal alignment agent, and further irradiating the fired liquid crystal alignment agent with polarized ultraviolet rays.

15. A liquid crystal display element comprising the liquid crystal alignment film according to claim 13.