WO2016158942A1

WO2016158942A1 - Liquid crystal alignment agent, liquid crystal alignment film, and liquid crystal display element

Info

Publication number: WO2016158942A1
Application number: PCT/JP2016/060107
Authority: WO
Inventors: 幸司巴; 秀則石井; 達也結城; 早紀相馬
Original assignee: 日産化学工業株式会社
Priority date: 2015-03-30
Filing date: 2016-03-29
Publication date: 2016-10-06
Also published as: TW201708317A; CN107615147A; KR20170131548A; JP6700619B2; JPWO2016158942A1; KR102591734B1

Abstract

A liquid crystal alignment agent used to form a polyimide film by being applied to a substrate and heat treated, the liquid crystal alignment agent containing: at least one species of polymer selected from the group consisting of a polyimide precursor obtained by reacting a tetracarboxylic acid derivative and a diamine component containing a specific diamine, and a polyimide obtained by imidization of the polyimide precursor; and at least one species of solvent selected from the group consisting of the compounds represented by formula (1) and formula (2).

Description

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

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

The liquid crystal alignment film is a film for controlling the alignment of liquid crystal molecules in a certain direction in a liquid crystal display element or a retardation plate using a polymerizable liquid crystal. For example, a liquid crystal display element has a structure in which liquid crystal molecules forming a liquid crystal layer are sandwiched between liquid crystal alignment films formed on the surfaces of a pair of substrates.

The liquid crystal alignment film can be configured by forming a polymer film on a substrate. As the polymer film, a highly heat-resistant and highly reliable polyimide film or the like can be used.
As a method for forming a polymer film to be a liquid crystal alignment film on a substrate, a liquid crystal alignment agent containing components is used for forming the polymer film, and the coating film is formed on the substrate to form a liquid crystal alignment film. A method for obtaining a molecular film is known.

In the process of producing a liquid crystal alignment film, when a liquid crystal aligning agent is applied to a substrate, it is often industrially performed by a flexographic printing method or an ink jet printing method. At that time, a poor solvent typified by butyl cellosolve is used in combination with a good solvent as a solvent for the coating solution in order to improve the applicability (printability) of the liquid crystal aligning agent when applying the liquid crystal aligning agent to the substrate. (For example, refer to Patent Document 1 and Patent Document 2).

JP 2010-97188 A JP 2010-156934 A

However, butyl cellosolve has been pointed out to be toxic and has a problem that it is not preferable for use. Therefore, there has been a demand for a liquid crystal aligning agent containing another solvent that can reduce the amount of butyl cellosolve used in place of or in combination with butyl cellosolve while maintaining high printability.

In view of such circumstances, an object of the present invention is to provide a liquid crystal aligning agent having high printability and excellent safety in use, a liquid crystal alignment film using the liquid crystal aligning agent, and a liquid crystal display element.

The present invention includes the following 1. ~ 7. Is a summary.

1. A liquid crystal aligning agent used for forming a polyimide film by coating on a substrate and subjecting to a heat treatment, represented by a tetracarboxylic acid derivative and the following formulas (YA-1) to (YA-20) At least one polymer selected from the group consisting of a polyimide precursor obtained by reacting with a diamine component containing at least one diamine selected from the group consisting of the above compounds, and a polyimide obtained by imidizing it. And at least one solvent selected from the group consisting of compounds represented by the following formula (1) and the following formula (2). In the formula, Boc (Boc group) represents a tert-butoxycarbonyl group.

2. The content of the compound represented by the formula (1) in the solvent is 5% by mass or more. Liquid crystal aligning agent as described in.

3. The content of the compound represented by the formula (2) in the solvent is 10% by mass or more. Or 2. Liquid crystal aligning agent as described in.

4. The above-mentioned 1. characterized in that the application is inkjet printing. ~ 3. The liquid crystal aligning agent as described in any one of these.

5. The above-mentioned 1. characterized in that the application is flexographic printing. ~ 3. The liquid crystal aligning agent as described in any one of these.

6. Above 1. ~ 5. A liquid crystal alignment film obtained by applying the liquid crystal aligning agent according to any one of the above to a substrate and subjecting it to a heat treatment.

7. Above 6. A liquid crystal display element comprising the liquid crystal alignment film described in 1.

According to the present invention, it is possible to provide a liquid crystal aligning agent having high printability and excellent safety in use, and a liquid crystal alignment film and a liquid crystal display element using the liquid crystal aligning agent.

Hereinafter, the present invention will be described in more detail.
The liquid crystal aligning agent of the present invention comprises a tetracarboxylic acid derivative and a specific diamine (at least one diamine selected from the group consisting of compounds represented by formula (YA-1) to formula (YA-20) described later). It contains at least one polymer selected from the group consisting of a polyimide precursor obtained by reacting the contained diamine component and a polyimide obtained by imidizing it. Examples of the polyimide precursor include polyamic acid and polyamic acid ester. And the liquid crystal aligning agent of this invention contains the at least 1 type of solvent chosen from the group which consists of a compound represented by following formula (1) and following formula (2).

Hereinafter, a polyimide precursor, polyimide, a diamine compound having a specific structure essential for polymerization thereof, and a solvent, which are components that can be contained in the liquid crystal aligning agent of the present invention, will be described. And the liquid crystal aligning agent of this invention comprised including them is demonstrated.

<Polyimide precursor>
The polyimide precursor contained in the liquid crystal aligning agent of this invention points out a polyamic acid and polyamic acid ester, and has a structural unit represented by following formula (3).

In the above formula (3), R ₁ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and A ₁ and A ₂ may each independently have a hydrogen atom or a substituent. An alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, or an alkynyl group having 2 to 10 carbon atoms.

In the above formula (3), R ₁ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, preferably 1 to 2 carbon atoms. In the polyamic acid ester, the temperature at which imidization proceeds increases as the number of carbon atoms in the alkyl group increases. Therefore, R ₁ is particularly preferably a methyl group from the viewpoint of ease of imidization by heat.

In the above formula (3), A ₁ and A ₂ are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, or a substituent. Examples thereof include alkynyl groups having 2 to 10 carbon atoms. Specific examples of the alkyl group having 1 to 10 carbon atoms include methyl group, ethyl group, propyl group, butyl group, t-butyl group, hexyl group, octyl group, decyl group, cyclopentyl group, cyclohexyl group, and bicyclohexyl group. Etc. Examples of the alkenyl group having 2 to 10 carbon atoms include those in which one or more CH—CH structures present in the above alkyl group are replaced with a C═C structure. Group, 1-propenyl group, isopropenyl group, 2-butenyl group, 1,3-butadienyl group, 2-pentenyl group, 2-hexenyl group, cyclopropenyl group, cyclopentenyl group, cyclohexenyl group and the like. Examples of the alkynyl group having 2 to 10 carbon atoms include those obtained by replacing one or more CH ₂ —CH ₂ structures present in the alkyl group with a C≡C structure, specifically, an ethynyl group, Examples thereof include 1-propynyl group and 2-propynyl group.

The alkyl group having 1 to 10 carbon atoms, the alkenyl group having 2 to 10 carbon atoms, and the alkynyl group having 2 to 10 carbon atoms may have a substituent, and further, a ring structure is formed by the substituent. Also good. The formation of a ring structure by a substituent means that the substituents or a substituent and a part of the mother skeleton are bonded to form a ring structure.

Examples of this substituent include halogen groups, hydroxyl groups, thiol groups, nitro groups, aryl groups, organooxy groups, organothio groups, organosilyl groups, acyl groups, ester groups, thioester groups, phosphate ester groups, amide groups, Examples thereof include an alkyl group, an alkenyl group, and an alkynyl group.

Examples of the halogen group as a substituent include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. A phenyl group is mentioned as an aryl group which is a substituent. This aryl group may be further substituted with the above-mentioned other substituents.

The organooxy group that is a substituent can have a structure represented by OR. The R may be the same or different, and examples thereof include the aforementioned alkyl group, alkenyl group, alkynyl group, and aryl group. These Rs may be further substituted with the aforementioned substituent. Specific examples of the organooxy group include methoxy group, ethoxy group, propyloxy group, butoxy group, pentyloxy group, hexyloxy group, heptyloxy group, octyloxy group and the like.

As the organothio group which is a substituent, a structure represented by —S—R can be shown. Examples of R include the aforementioned alkyl group, alkenyl group, alkynyl group, aryl group and the like. These Rs may be further substituted with the aforementioned substituent. Specific examples of the organothio group include a methylthio group, an ethylthio group, a propylthio group, a butylthio group, a pentylthio group, a hexylthio group, a heptylthio group, and an octylthio group.

The organosilyl group as a substituent can have a structure represented by —Si— (R) ₃ . The Rs may be the same or different, and examples thereof include the aforementioned alkyl group, alkenyl group, alkynyl group, and aryl group. These Rs may be further substituted with the aforementioned substituent. Specific examples of the organosilyl group include a trimethylsilyl group, a triethylsilyl group, a tripropylsilyl group, a tributylsilyl group, a tripentylsilyl group, a trihexylsilyl group, a pentyldimethylsilyl group, and a hexyldimethylsilyl group.

The acyl group as a substituent can have a structure represented by —C (O) —R. Examples of R include the aforementioned alkyl group, alkenyl group, and aryl group. These Rs may be further substituted with the aforementioned substituent. Specific examples of the acyl group include formyl group, acetyl group, propionyl group, butyryl group, isobutyryl group, valeryl group, isovaleryl group, benzoyl group and the like.

As the ester group which is a substituent, a structure represented by —C (O) O—R or OC (O) —R can be shown. Examples of R include the aforementioned alkyl group, alkenyl group, alkynyl group, aryl group and the like. These Rs may be further substituted with the aforementioned substituent.
As the thioester group as a substituent, a structure represented by —C (S) O—R or OC (S) —R can be shown. Examples of R include the aforementioned alkyl group, alkenyl group, alkynyl group, aryl group and the like. These Rs may be further substituted with the aforementioned substituent.

The phosphate group which is a substituent can have a structure represented by —OP (O) — (OR) ₂ . The R may be the same or different, and examples thereof include the aforementioned alkyl group, alkenyl group, alkynyl group, and aryl group. These Rs may be further substituted with the aforementioned substituent.

The amide group as a substituent includes —C (O) NH ₂ , —C (O) NHR, —NHC (O) R, —C (O) N (R) ₂ , or —NRC (O) R. The structure represented can be shown. R may be the same or different, and examples thereof include the aforementioned alkyl group, alkenyl group, alkynyl group, and aryl group. These Rs may be further substituted with the aforementioned substituent.

Examples of the aryl group that is a substituent include the same aryl groups as described above. This aryl group may be further substituted with the above-mentioned other substituents. Examples of the alkyl group as a substituent include the same alkyl groups as described above. This alkyl group may be further substituted with the above-mentioned other substituents. Examples of the alkenyl group as a substituent include the same alkenyl groups as those described above. This alkenyl group may be further substituted with the above-mentioned other substituents. Examples of the alkynyl group that is a substituent include the same alkynyl groups as those described above. This alkynyl group may be further substituted with the above-mentioned other substituents.

In general, when a bulky structure is introduced, there is a possibility that the reactivity of the amino group and the liquid crystal orientation may be lowered. Therefore, as A ₁ and A ₂ , a hydrogen atom or a carbon atom that may have a substituent is 1 An alkyl group of 1 to 5 is more preferable, and a hydrogen atom, a methyl group, or an ethyl group is particularly preferable.

In the above formula (3), the structure of X ₁ is not particularly limited as long as it is a tetravalent organic group, and two or more kinds may be mixed. If Specific examples of X _1, include X-1 ~ X-47 shown below. Among these, from the availability of monomers, X ₁ is X-1, X-2, X-3, X-4, X-5, X-6, X-8, X-16, X-19, X -21, X-25, X-26, X-27, X-28, X-32 or X-47 are preferred.

In the above formula (3), Y ₁ corresponds to the structure of the diamine component used in the present invention. The diamine component used in the present invention contains a specific diamine (at least one diamine selected from the group consisting of compounds represented by formula (YA-1) to formula (YA-20) described later). Therefore, Y ₁ has a structure corresponding to the specific diamine. However, it is not always necessary that Y ₁ has a structure corresponding to the specific diamine. A part of Y ₁ may contain a structure corresponding to a diamine other than the specific diamine (other diamine). Specific examples of Y ₁ including the case where other diamines are used in combination include the following Y-1 to Y-108, but are not limited thereto. Among these, specific examples of Y ₁ include Y-7, Y-8, Y-13, Y-18, Y-19, Y-42, Y from the viewpoints of diamine reactivity and polymer solubility. -43, Y-45, Y-55, Y-59, Y-74, Y-78, Y-79, Y-80, Y-81, or Y-82 are preferred, and Y-19 (for example, described later) Diamine (YA-8)), Y-42 (for example, diamine (YA-5) described later), Y-43 (for example, diamine (YA-1) described later), Y-45 (for example) For example, corresponding to diamine (YA-2) described later), Y-74 (for example, corresponding to diamine (YA-9) described later), Y-81 (for example, corresponding to diamine (YA-12) described later) or Y-82 (for example, corresponding to diamine (YA-3) described later) is more preferable.

The diamine component used in the present invention contains at least one diamine selected from the group consisting of compounds represented by the following formula (YA-1) to the following formula (YA-20). As described above, a part of Y ₁ may contain a structure corresponding to another diamine, that is, the diamine component used in the present invention may contain another diamine. Diamines providing Y ₁ other than Y-1 to Y-108 can also be used as other diamines within the scope of the present invention. Specific examples of other diamines are shown below (YB-1 to YB-7). Other diamines are not limited to the following.

The polyimide precursor contained in the liquid crystal aligning agent of the present invention is preferably a polyimide precursor having at least one of primary amine, secondary amine, carboxylic acid and urea group, and at least one of primary amine and urea group. A polyimide precursor having two is more preferable.

<Production Method of Polyimide Precursor-Production of Polyamic Acid>
The polyamic acid which is a polyimide precursor having the structural unit represented by the above formula (3) is obtained by a reaction between a tetracarboxylic dianhydride which is a tetracarboxylic acid derivative and a diamine component.

In obtaining a polyamic acid by the reaction of tetracarboxylic dianhydride and a diamine component, a known synthesis method can be used. The synthesis method is a method in which a tetracarboxylic dianhydride and a diamine component are reacted in an organic solvent. The reaction of tetracarboxylic dianhydride and diamine is advantageous in that it proceeds relatively easily in an organic solvent and no by-product is generated.

The organic solvent used for the reaction between the tetracarboxylic dianhydride and the diamine component is not particularly limited as long as the generated polyamic acid dissolves. The organic solvent here may contain at least one solvent selected from the group consisting of the compounds represented by the above formula (1) and the above formula (2). Specific examples of the organic solvent that can be used are listed below.

N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-methylcaprolactam, dimethyl sulfoxide, tetramethyl urea, pyridine, dimethyl sulfone, hexamethyl sulfoxide , Γ-butyrolactone, isopropyl alcohol, methoxymethylpentanol, dipentene, ethyl amyl ketone, methyl nonyl ketone, methyl ethyl ketone, methyl isoamyl ketone, methyl isopropyl ketone, methyl cellosolve, ethyl cellosolve, methyl cellosolve acetate, ethyl cellosolve acetate, butyl Carbitol, ethyl carbitol, ethylene glycol, ethylene glycol monoacetate, ethylene glycol monoisopropyl ether, ethyl Glycol monobutyl ether, propylene glycol, propylene glycol monoacetate, propylene glycol monomethyl ether, propylene glycol-tert-butyl ether, dipropylene glycol monomethyl ether, diethylene glycol, diethylene glycol monoacetate, diethylene glycol dimethyl ether, dipropylene glycol monoacetate monomethyl ether, dipropylene Glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monoacetate monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monoacetate monopropyl ether, 3-methyl-3-methoxybutyl acetate, tripropiate Lenglycol methyl ether, 3-methyl-3-methoxybutanol, diisopropyl ether, ethyl isobutyl ether, diisobutylene, amyl acetate, butyl butyrate, butyl ether, diisobutyl ketone, methylcyclohexene, propyl ether, dihexyl ether, dioxane, n- Hexane, n-pentane, n-octane, diethyl ether, cyclohexanone, ethylene carbonate, propylene carbonate, methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, n-butyl acetate, propylene glycol monoethyl ether, methyl pyruvate, Ethyl pyruvate, methyl 3-methoxypropionate, methyl ethyl 3-ethoxypropionate, ethyl 3-methoxypropionate, 3-ethoxypropio Acid, 3-methoxypropionic acid, propyl 3-methoxypropionate, butyl 3-methoxypropionate, diglyme, 4-hydroxy-4-methyl-2-pentanone, 3-methoxy-N, N-dimethylpropanamide, 3- Examples thereof include ethoxy-N, N-dimethylpropanamide, 3-butoxy-N, N-dimethylpropanamide and the like.

These exemplified solvents may be used alone or in combination. Furthermore, even if the solvent does not dissolve the polyamic acid, it may be used by mixing with the above solvent as long as the produced polyamic acid does not precipitate.

Since water in the organic solvent inhibits the polymerization reaction and further causes hydrolysis of the generated polyamic acid, it is preferable to use a dehydrated and dried organic solvent as much as possible.

When the tetracarboxylic dianhydride and the diamine component are reacted in an organic solvent, the solution in which the diamine component is dispersed or dissolved in the organic solvent is stirred, and the tetracarboxylic dianhydride is used as it is or in an organic solvent. A method of adding by dispersing or dissolving, a method of adding a diamine component to a solution in which tetracarboxylic dianhydride is dispersed or dissolved in an organic solvent, and alternately adding a tetracarboxylic dianhydride and a diamine component. Any of these methods may be used. When the tetracarboxylic dianhydride or diamine component is composed of multiple types of compounds, they may be reacted in a premixed state, may be individually reacted sequentially, or may be further mixed with individually reacted low molecular weight substances. It is good also as a high molecular weight body by making it react.

The polymerization temperature at that time can be selected from -20 ° C. to 150 ° C., but is preferably in the range of −5 ° C. to 100 ° C. The reaction can be carried out at any concentration, but if the concentration is too low, it is difficult to obtain a high molecular weight polymer, and if the concentration is too high, the viscosity of the reaction solution becomes too high and uniform stirring is difficult. Therefore, the total concentration of the tetracarboxylic dianhydride and the diamine component in the reaction solution is preferably 1% by mass to 50% by mass, more preferably 5% by mass to 30% by mass. The initial stage of the reaction is carried out at a high concentration, and then an organic solvent can be added.

In the polymerization reaction of polyamic acid, the ratio of the total number of moles of tetracarboxylic dianhydride to the total number of moles of the diamine component is preferably 0.8 to 1.2. Similar to the normal polycondensation reaction, the closer the molar ratio is to 1.0, the higher the molecular weight of the polyamic acid produced.

<Production Method of Polyimide Precursor-Production of Polyamic Acid Ester>
The polyamic acid ester which is a polyimide precursor having the structural unit represented by the above formula (3) is a method of (A), (B) or (C) shown below using a tetracarboxylic acid derivative and a diamine compound. Can be manufactured.

(A) When manufacturing from polyamic acid A polyamic acid ester can be manufactured by esterifying the polyamic acid obtained from tetracarboxylic dianhydride and diamine.
Specifically, the polyamic acid and the esterifying agent are reacted in the presence of an organic solvent at −20 ° C. to 150 ° C., preferably 0 ° C. to 50 ° C., for 30 minutes to 24 hours, preferably 1 hour to 4 hours. Can be manufactured by.

The esterifying agent is preferably one that can be easily removed by purification, and N, N-dimethylformamide dimethyl acetal, N, N-dimethylformamide diethyl acetal, N, N-dimethylformamide dipropyl acetal, N, N-dimethylformamide Dineopentyl butyl acetal, N, N-dimethylformamide di-t-butyl acetal, 1-methyl-3-p-tolyltriazene, 1-ethyl-3-p-tolyltriazene, 1-propyl-3-p -Tolyltriazene, 4- (4,6-dimethoxy-1,3,5-triazin-2-yl) -4-methylmorpholinium chloride and the like. The addition amount of the esterifying agent is preferably 2 to 6 molar equivalents relative to 1 mol of the polyamic acid repeating unit.

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

(B) When manufacturing by reaction with tetracarboxylic-acid diester dichloride and diamine Polyamic acid ester can be manufactured from tetracarboxylic-acid diester dichloride and diamine.

Specifically, tetracarboxylic acid diester dichloride and diamine in the presence of a base and an organic solvent at −20 ° C. to 150 ° C., preferably 0 ° C. to 50 ° C., for 30 minutes to 24 hours, preferably 1 to 4 hours. It can be produced by reacting.
As the base, pyridine, triethylamine, 4-dimethylaminopyridine and the like can be used, but pyridine is preferable because the reaction proceeds gently. The addition amount of the base is preferably 2 to 4 times with respect to the tetracarboxylic acid diester dichloride from the viewpoint of easy removal and high molecular weight.

The solvent used in the above reaction is preferably N-methyl-2-pyrrolidone or γ-butyrolactone in view of the solubility of the monomer and polymer, and these may be used alone or in combination. The polymer concentration at the time of production is preferably 1% by mass to 30% by mass, and more preferably 5% by mass to 20% by mass from the viewpoint that polymer precipitation is unlikely 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 for the production of the polyamic acid ester is preferably dehydrated as much as possible, and it is preferable to prevent mixing of outside air in a nitrogen atmosphere.

(C) When manufacturing from tetracarboxylic-acid diester and diamine Polyamic acid ester can be manufactured by polycondensing tetracarboxylic-acid diester and diamine.

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

Examples of the condensing agent include triphenyl phosphite, dicyclohexylcarbodiimide, 1-ethyl-3- (3-dimethylaminopropyl) carbodiimide hydrochloride, N, N′-carbonyldiimidazole, dimethoxy-1,3,5-triazide. Nylmethylmorpholinium, O- (benzotriazol-1-yl) -N, N, N ′, N′-tetramethyluronium tetrafluoroborate, O- (benzotriazol-1-yl) -N, N , N ′, N′-tetramethyluronium hexafluorophosphate, (2,3-dihydro-2-thioxo-3-benzoxazolyl) phosphonate diphenyl, and the like. The addition amount of the condensing agent is preferably 2 to 3 times by mole with respect to the tetracarboxylic acid diester.

As the base, tertiary amines such as pyridine and triethylamine can be used. The addition amount of the base is preferably 2 to 4 times by mole with respect to the diamine component from the viewpoint of easy removal and high molecular weight.

In the above reaction, the reaction proceeds efficiently by adding Lewis acid as an additive. As the Lewis acid, lithium halides such as lithium chloride and lithium bromide are preferable. The addition amount of the Lewis acid is preferably 0 to 1.0 mol times relative to the diamine component.

Among the above-mentioned three polyamic acid ester production methods, the production method (C) is particularly preferable because a high molecular weight polyamic acid ester can be obtained with good reproducibility. The polyamic acid ester solution obtained as described above can be polymerized by pouring into a poor solvent while stirring well. Precipitation is performed several times, and after washing with a poor solvent, purified polyamic acid ester powder can be obtained by drying at room temperature or by heating.

<Polyimide>
The polyimide used in the present invention can be produced by imidizing the aforementioned polyamic acid ester or polyamic acid, which is a polyimide precursor. The imidization reaction for dehydrating and cyclizing the polyimide precursor is generally thermal imidization or chemical imidation, but chemical imidation in which the imidization reaction proceeds at a relatively low temperature may reduce the molecular weight of the resulting polyimide. Less likely to occur.

Chemical imidization can be performed by stirring the polyimide precursor in an organic solvent in the presence of a basic catalyst and an acid anhydride. The reaction temperature at this time is −20 to 250 ° C., preferably 0 to 180 ° C., and the reaction time can be 1 to 100 hours. The amount of the basic catalyst is 0.5 to 30 mol times, preferably 2 to 20 mol times of the polyimide precursor, and the amount of acid anhydride is 1 to 50 mol times, preferably 3 to 30 mol of the polyimide precursor. Is double. If the amount of the basic catalyst or acid anhydride is small, the reaction does not proceed sufficiently. If the amount is too large, it becomes difficult to completely remove the reaction after completion of the reaction.

Examples of basic catalysts used for imidization include pyridine, triethylamine, trimethylamine, tributylamine, and trioctylamine. Of these, pyridine is preferable because it has an appropriate basicity for proceeding with the reaction.

Examples of the acid anhydride include acetic anhydride, trimellitic anhydride, pyromellitic anhydride, and the like. Among them, use of acetic anhydride is preferable because purification after completion of the reaction is easy. As an organic solvent, the solvent used at the time of the above-mentioned polyamic acid polymerization reaction can be used. The imidation rate by chemical imidation can be controlled by adjusting the amount of catalyst, reaction temperature, and reaction time.

In the polyimide solution thus obtained, the added catalyst remains in the solution. Therefore, in order to use it for the liquid crystal aligning agent of the present invention, this polyimide solution is put into a poor solvent which is being stirred. It is preferable to use the polyimide after precipitation. Although it does not specifically limit as a poor solvent used for precipitation collection | recovery of a polyimide, Methanol, acetone, hexane, a butyl cellosolve, heptane, methyl ethyl ketone, methyl isobutyl ketone, ethanol, toluene, benzene etc. can be illustrated. The polyimide precipitated by adding it to a poor solvent can be recovered by filtration, washing, and drying at normal temperature or under reduced pressure at room temperature or by heating. By further dissolving the powder in a good solvent and reprecipitating it 2 to 10 times, the polyimide can be purified. When impurities cannot be completely removed by a single precipitation recovery operation, it is preferable to repeat this purification step. Mixing or sequentially using, for example, three or more kinds of poor solvents such as alcohols, ketones and hydrocarbons as the poor solvent in the repeated purification step is preferable because the purification efficiency is further increased.

The imidation ratio of the polyimide contained in the liquid crystal aligning agent of the present invention is not particularly limited. What is necessary is just to set to arbitrary values in consideration of the solubility of a polyimide. The molecular weight of the polyimide contained in the liquid crystal aligning agent of the present invention is not particularly limited, but if the molecular weight of the polyimide is too small, the strength of the resulting coating film may be insufficient, and conversely, the molecular weight of the polyimide is too large. And the viscosity of the liquid crystal aligning agent manufactured may become high too much, and the workability | operativity at the time of coating-film formation and the uniformity of a coating film may worsen. Accordingly, the weight average molecular weight of the polyimide used for the liquid crystal aligning agent of the present invention is preferably 2,000 to 500,000, more preferably 5,000 to 300,000.

<Other compounds>
A compound other than the above (other compounds) may be added to the liquid crystal aligning agent of the present invention as long as the effects of the present invention are not impaired. For example, for the purpose of changing the electrical properties such as the dielectric constant and conductivity of the liquid crystal alignment film, the crosslinkable compound is intended to increase the hardness and density of the dielectric and conductive material, and further to the liquid crystal alignment film. May be added.

Examples of other compounds include compounds having a blocked isocyanate group described in Japanese Patent Application No. 2014-053902. A compound having a blocked isocyanate group has a blocked isocyanate group in which the isocyanate group (—NCO) is blocked by a protective group in the molecule, and when exposed to a high temperature during heating and baking during the formation of a liquid crystal alignment film, the protective group (block The portion) is dissociated by thermal dissociation, and a crosslinking reaction proceeds with a polymer such as polyimide constituting the liquid crystal alignment film through the generated isocyanate group. For example, the compound which has group represented by Formula (4) in a molecule | numerator is mentioned.

(In formula (4), R ² represents an organic group in the block part.)

<Liquid crystal aligning agent>
The liquid crystal aligning agent of this invention is a coating liquid for forming a liquid crystal aligning film, and is a solution which the resin component for forming a resin film melt | dissolved in the organic solvent. Here, the said resin component is a resin component containing the at least 1 sort (s) of polymer chosen from the group which consists of said polyimide precursor and a polyimide. The content of the resin component in the liquid crystal aligning agent is preferably 1% by mass to 20% by mass, more preferably 3% by mass to 15% by mass, and still more preferably 3% by mass to 10% by mass.

In the present invention, all of the resin components may be the above-mentioned polymers, or other polymers may be mixed. In that case, the content of the polymer other than the above-mentioned polymer in the resin component is 0.5% by mass to 15% by mass, preferably 1% by mass to 10% by mass.

The organic solvent used for the liquid crystal aligning agent of the present invention contains at least one solvent selected from the group consisting of the compounds represented by the above formula (1) and the above formula (2). According to this, a liquid crystal aligning agent can be comprised without using the butyl cellosolve to which toxicity is pointed out, or reducing the usage-amount of a butyl cellosolve. Therefore, it becomes a liquid crystal aligning agent excellent in safety. In addition, the liquid crystal aligning agent of the present invention containing at least one solvent selected from the group consisting of the compounds represented by the above formula (1) and the above formula (2) seems to be confirmed in the examples described later. In addition, it has high printability.

Here, the content of the compound represented by the above formula (1) in the organic solvent (organic solvent used for the liquid crystal aligning agent) is preferably 5% by mass or more. In this case, it becomes easy to form a coating film suitably on a board | substrate, for example by inkjet printing. In other words, when a coating film is formed by inkjet printing, a liquid crystal aligning agent in which the compound represented by the above formula (1) in the organic solvent (organic solvent used for the liquid crystal aligning agent) is 5% by mass or more is used. It is preferable to configure.

The compound represented by the above formula (1) is called dipropylene glycol monomethyl ether or the like. The compound represented by the above formula (1) has a relatively simple structure and is easily available.

The compound represented by the above formula (2) is called propylene glycol monobutyl ether or the like. The content of the compound represented by the above formula (2) in the organic solvent (organic solvent used for the liquid crystal aligning agent) is preferably 10% by mass or more. In this case, it becomes easy to suitably form a coating film on the substrate by, for example, ink jet printing or flexographic printing. Conversely, when forming a coating film by flexographic printing as well as inkjet printing, the compound represented by the above formula (2) in the organic solvent (organic solvent used for the liquid crystal aligning agent) is 10% by mass or more. It is preferable to constitute a certain liquid crystal aligning agent.

The organic solvent used for the liquid crystal aligning agent may contain a solvent (other solvent) other than the solvent represented by the above formula (1) and the above formula (2). Specific examples of other solvents are listed below.

N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methylcaprolactam, 2-pyrrolidone, N-ethylpyrrolidone, N-vinylpyrrolidone, dimethylsulfoxide, tetramethylurea, pyridine, Dimethylsulfone, hexamethylsulfoxide, γ-butyrolactone, 3-methoxy-N, N-dimethylpropanamide, 3-ethoxy-N, N-dimethylpropanamide, 3-butoxy-N, N-dimethylpropanamide, 1,3 -Dimethyl-imidazolidinone, ethyl amyl ketone, methyl nonyl ketone, methyl ethyl ketone, methyl isoamyl ketone, methyl isopropyl ketone, cyclohexanone, ethylene carbonate, propylene carbonate, diglyme, 4-hydroxy- - and methyl-2-pentanone and the like. These may be used alone or in combination.

Although not preferred in use, the liquid crystal aligning agent may contain butyl cellosolve. Even if the liquid crystal aligning agent contains butyl cellosolve, the amount of the butyl cellosolve used is reduced by the amount containing at least one solvent selected from the group consisting of the compounds represented by formula (1) and formula (2). it can.

The liquid crystal aligning agent of the present invention may contain components other than those described above. Examples thereof include solvents and compounds that improve the film thickness uniformity and surface smoothness when a liquid crystal aligning agent is applied, and compounds that improve the adhesion between the liquid crystal aligning film and the substrate.

Specific examples of solvents (poor solvents) that improve film thickness uniformity and surface smoothness include, for example, those described in Japanese Patent Application No. 2014-053902.

The poor solvent may be used alone or in combination. When the above solvent is used, the content thereof is preferably 5% by mass to 80% by mass, and more preferably 20% by mass to 60% by mass with respect to the total solvent contained in the liquid crystal aligning agent.

Examples of the compound that improves film thickness uniformity and surface smoothness include fluorine-based surfactants, silicone-based surfactants, nonionic surfactants, and the like described in Japanese Patent Application No. 2014-053902. .

The ratio of the surfactant used is preferably 0.01 parts by mass to 2 parts by mass, more preferably 0.01 parts by mass to 1 part by mass with respect to 100 parts by mass of the resin component contained in the liquid crystal aligning agent. is there.

Specific examples of compounds that improve the adhesion between the liquid crystal alignment film and the substrate include functional silane-containing compounds and epoxy group-containing compounds described in Japanese Patent Application No. 2014-053902.

When using a compound that improves the adhesion to the substrate, the amount used is preferably 0.1 to 30 parts by mass with respect to 100 parts by mass of the resin component contained in the liquid crystal aligning agent. More preferably, it is 1 to 20 parts by mass. If the amount used is less than 0.1 part by mass, the effect of improving the adhesion cannot be expected, and if it exceeds 30 parts by mass, the liquid crystal orientation of the liquid crystal alignment film formed may be lowered.

In addition to the above, the liquid crystal aligning agent of the present invention has a dielectric or conductive material for the purpose of changing the electrical properties such as the dielectric constant and conductivity of the liquid crystal aligning film, as long as the effects of the present invention are not impaired. Further, a crosslinkable compound for the purpose of increasing the hardness and density of the liquid crystal alignment film may be added.

Based on the above, examples of solvents and composition ratios that can be used in the liquid crystal aligning agent of the present invention are as shown in the following table. Of course, the solvent which can be used with the liquid crystal aligning agent of this invention, and its composition ratio are not limited to the following table | surface.

(Good solvent)
NMP: N-methyl-2-pyrrolidone GBL: γ-butyrolactone (poor solvent)
BCS: Butyl cellosolve (ethylene glycol monobutyl ether)
DPM: Dipropylene glycol monomethyl ether (formula (1) above)
PB: Propylene glycol monobutyl ether (formula (2) above)

<Liquid crystal alignment film>
The liquid crystal aligning agent of the present invention can be formed into a coating film by preferably filtering before applying to the substrate, applying to the substrate, drying by pre-baking, and then baking by heating. And a liquid crystal aligning film can be formed by rubbing this coating-film surface.

When applying the liquid crystal aligning agent of the present invention to a substrate, a highly transparent substrate can be used. As such a substrate, for example, a plastic substrate such as an acrylic substrate or a polycarbonate substrate can be used in addition to a glass substrate. When using the liquid crystal aligning agent of this invention in manufacture of a liquid crystal display element, it is preferable to form a liquid crystal aligning film using the board | substrate with which the ITO (Indium Tin Oxide) electrode etc. for a liquid crystal drive were formed. In the case of manufacturing a reflective liquid crystal display element, an opaque substrate such as a silicon wafer can be used as long as only one substrate is used. In this case, a material that reflects light such as aluminum may be used for the electrode. it can.

Examples of the method for applying the liquid crystal aligning agent of the present invention on a substrate include an inkjet printing method and a flexographic printing method. As mentioned above, when forming a coating film on a board | substrate using an inkjet printing method, it is preferable that a liquid crystal aligning agent contains the solvent represented by the said Formula (1) at least. Moreover, when forming a coating film on a board | substrate using a flexographic printing method, it is preferable that a liquid crystal aligning agent contains the solvent represented by the said Formula (2) at least. In addition, examples of the coating method of the present invention include screen printing, offset printing, dip method, roll coater method, slit coater method, spinner method, and spray method, and these may be used depending on the purpose.

The step of drying by pre-baking after applying the liquid crystal aligning agent is not necessarily required, but when the time from application to heating and baking is not constant for each substrate, or when heating and baking is not performed immediately after application, It is preferable to include a drying step. The drying by this pre-bake should just evaporate the solvent to such an extent that the coating film shape does not deform | transform by conveyance of a board | substrate.

The drying means is not particularly limited. As a specific example, a method of drying on a hot plate at 50 ° C. to 120 ° C., preferably 80 ° C. to 120 ° C. for 0.5 minutes to 30 minutes, preferably 1 minute to 5 minutes is preferable.

The substrate coated with the liquid crystal aligning agent can be baked at a temperature of 120 ° C. to 350 ° C. by a heating means such as a hot plate, a thermal circulation oven or an IR (infrared) oven. However, baking is preferably performed at a temperature that is 10 ° C. or more higher than the heat treatment temperature required for the manufacturing process of the liquid crystal display element, such as sealing agent curing.

If the thickness of the coating film after baking is too thick, it is disadvantageous in terms of power consumption of the liquid crystal display element, and if it is too thin, the reliability of the liquid crystal display element may be lowered. Therefore, it is preferably 10 nm to 200 nm, more preferably 50 nm to 100 nm.

For the rubbing treatment of the coating surface formed on the substrate as described above, an existing rubbing apparatus can be used. Examples of the material of the rubbing cloth at this time include cotton, rayon, and nylon. As conditions for the rubbing treatment, generally, conditions of a rotational speed of 300 to 2000 rpm, a feed speed of 5 to 100 mm / s, and an indentation amount of 0.1 to 1.0 mm are used. Thereafter, residues generated by rubbing are removed by ultrasonic cleaning using pure water, alcohol, or the like.

The liquid crystal aligning agent of the present invention can produce a liquid crystal display by a known method using the substrate with the liquid crystal aligning film after the liquid crystal aligning film is formed on the substrate by the above method.

<Liquid crystal display element>
The liquid crystal display element of the present invention is a liquid crystal display element obtained by obtaining a substrate with a liquid crystal alignment film from the liquid crystal aligning agent of the present invention by the method described above, and then preparing a liquid crystal cell by a known method.
An example of a method for manufacturing a liquid crystal display element is as follows. First, a pair of substrates on which a liquid crystal alignment film is formed is prepared, and they are preferably sandwiched by spacers of 1 μm to 30 μm, more preferably 2 μm to 10 μm, and the rubbing direction is an arbitrary angle of 0 ° to 270 °. Install it so that the surrounding area is fixed with a sealant. Next, liquid crystal is injected between the substrates and sealed. The method for enclosing the liquid crystal is not particularly limited, and examples thereof include a vacuum method in which liquid crystal is injected after reducing the pressure inside the manufactured liquid crystal cell, and a dropping method in which sealing is performed after dropping the liquid crystal.

Hereinafter, the present invention will be specifically described with reference to examples and the like, but the present invention is not limited to these examples. In addition, the symbol of a compound and a solvent is as follows.

(Good solvent)
NMP: N-methyl-2-pyrrolidone GBL: γ-butyrolactone (poor solvent)
PB: Propylene glycol monobutyl ether (formula (2) above)
BCS: Butyl cellosolve (ethylene glycol monobutyl ether)
DPM: Dipropylene glycol monomethyl ether (formula (1) above)

(Diamine)
DA-1: 1,5-bis (4-aminophenoxy) pentane (formula (YA-9: n = 5))
DA-2: 4,4′-diaminodiphenylamine (formula (YA-2))
DA-3: 4,4′-diaminodiphenylmethane (formula (YA-5))
DA-4: 1,3-diamino-4- [4- (trans-4-n-heptylcyclohexyl) phenoxy] benzene (diamine corresponding to the formula (Y-86: n = 6))
DA-5: 3,5-diaminobenzoic acid (formula (YA-19))
DA-6: p-phenylenediamine (formula (YA-7))
DA-7: N, N-diallylamino-2,4-diaminobenzene (diamine corresponding to formula (Y-15))
DA-8: 1,3-diamino-4- [4- (trans-4-n-heptylcyclohexyl) phenoxymethyl] benzene (diamine corresponding to the formula (Y-92: n = 6))

(Tetracarboxylic acid dihydrate)
CA-1: pyromellitic dianhydride CA-2: 1,2,3,4-cyclobutanetetracarboxylic dianhydride CA-3: 3,4-dicarboxy-1,2,3,4-tetrahydro- 1-Naphthalene succinic dianhydride CA-4: Bicyclo [3,3,0] octane-2,4,6,8-tetracarboxylic dianhydride

[Measurement of imidization ratio of polyimide]
The imidation ratio of polyimide in the synthesis example was measured as follows. 20 mg of polyimide powder was put into an NMR (nuclear magnetic resonance) sample tube (NMR sampling tube standard, φ5 (manufactured by Kusano Kagaku)), and deuterated dimethyl sulfoxide (DMSO-d6, 0.05 mass% TMS (tetramethylsilane)). (Mixed product) (0.53 ml) was added and completely dissolved by applying ultrasonic waves. This solution was measured for proton NMR at 500 MHz with an NMR measuring instrument (JNW-ECA500) (manufactured by JEOL Datum). The imidation rate is determined based on protons derived from structures that do not change before and after imidation as reference protons, and the peak integrated value of these protons and proton peaks derived from NH groups of amic acid that appear in the vicinity of 9.5 ppm to 10.0 ppm. It calculated | required by the following formula | equation using the integrated value.
Imidization rate (%) = (1−α · x / y) × 100

In the above formula, x is a proton peak integrated value derived from NH group of amic acid, y is a peak integrated value of reference proton, α is one NH group proton of amic acid in the case of polyamic acid (imidation rate is 0%) Is the number ratio of the reference proton to.

(Synthesis Example 1)
In a 200 mL four-necked flask equipped with a stirrer and a nitrogen introduction tube, 17.7 g (62.0 mmol) of DA-1 was weighed, 139 g of NMP was added, and the mixture was stirred and dissolved while feeding nitrogen. While stirring this diamine solution under water cooling, 12.9 g (59.2 mmol) of CA-1 was added, NMP was further added so that the solid concentration was 12% by mass, and 20% at 50 ° C. in a nitrogen atmosphere. The mixture was stirred for a time to obtain a polyamic acid solution (PAA-1).

(Synthesis Example 2)
In a 200 mL four-necked flask equipped with a stirrer and a nitrogen introducing tube, 7.97 g (40.0 mmol) of DA-2 was weighed, 98.6 g of NMP was added, and the mixture was stirred and dissolved while feeding nitrogen. While stirring this diamine solution under water cooling, 6.96 g (35.5 mmol) of CA-2 was added, 35.9 g of NMP was further added, and the mixture was stirred under water cooling for 3 hours while feeding nitrogen. Next, 1.98 g (10.0 mmol) of DA-3 and 17.9 g of NMP were added and stirred to dissolve, then 3.00 g (10.0 mmol) of CA-3 and 26.9 g of NMP were added. The mixture was stirred for 3 hours under cooling with water while feeding nitrogen, to obtain a polyamic acid solution (PAA-2).

(Example 1)
In a 200 mL Erlenmeyer flask containing a stir bar, 50.0 g of the polyamic acid solution (PAA-1) obtained in Synthesis Example 1 was collected, 19.1 g of NMP, and 1% by mass of 3-aminopropyltriethoxysilane. 5.60 g of NMP solution and 18.6 g of PB were added and stirred for 2 hours with a magnetic stirrer to obtain a liquid crystal aligning agent (A-1) having a concentration of 6.0% by mass.

In a 200 mL Erlenmeyer flask containing a stir bar, 50.0 g of the polyamic acid solution (PAA-2) obtained in Synthesis Example 2 was collected, 10.5 g of NMP, and 1% by mass of 3-aminopropyltriethoxysilane. 4.90 g of NMP solution and 16.3 g of PB were added and stirred with a magnetic stirrer for 2 hours to obtain a liquid crystal aligning agent (B-1) having a concentration of 6.0% by mass.

The liquid crystal aligning agent (A-1) and the liquid crystal aligning agent (B-1) are mixed in a mass ratio of 20:80 to obtain a liquid crystal aligning agent (C-1) having a concentration of 6.0% by mass. It was.

(Example 2)
In a 200 mL Erlenmeyer flask containing a stir bar, 50.0 g of the polyamic acid solution (PAA-1) obtained in Synthesis Example 1 was collected, 19.1 g of NMP, and 1% by mass of 3-aminopropyltriethoxysilane. 5.60 g of NMP solution containing, 9.30 g of PB and 9.30 of BCS were added and stirred for 2 hours with a magnetic stirrer to obtain a liquid crystal aligning agent (A-2) having a concentration of 6.0% by mass. .

In a 200 mL Erlenmeyer flask containing a stir bar, 50.0 g of the polyamic acid solution (PAA-2) obtained in Synthesis Example 2 was collected, 10.5 g of NMP, and 1% by mass of 3-aminopropyltriethoxysilane. 4.90 g of NMP solution containing, 8.18 g of PB and 8.18 g of BCS were added and stirred for 2 hours with a magnetic stirrer to obtain a liquid crystal aligning agent (B-2) having a concentration of 6.0% by mass. .

The liquid crystal aligning agent (A-2) and the liquid crystal aligning agent (B-2) are mixed in an amount of 20:80 to obtain a liquid crystal aligning agent (C-2) having a concentration of 6.0% by mass. It was.

(Example 3)
Into a 200 mL Erlenmeyer flask containing a stir bar, 50.0 g of the liquid crystal aligning agent (C-1) obtained in Example 1 was collected, 28.5 g of NMP and 7.14 g of PB were added, and a magnetic stirrer was added. By stirring for 2 hours, a liquid crystal aligning agent (C-3) having a concentration of 3.5% by mass was obtained.

Example 4
In a 200 mL Erlenmeyer flask containing a stir bar, 50.0 g of the polyamic acid solution (PAA-1) obtained in Synthesis Example 1 was collected, 48.0 g of NMP, 24.4 g of GBL, 3-aminopropyltrimethyl Add 5.60 g of NMP solution containing 1% by mass of ethoxysilane, 24.0 g of BCS, and 8.00 g of DPM, and stir with a magnetic stirrer for 2 hours to obtain a liquid crystal aligning agent (A -3) was obtained.

In a 200 mL Erlenmeyer flask containing a stir bar, 50.0 g of the polyamic acid solution (PAA-2) obtained in Synthesis Example 2 was collected, 42.0 g of NMP, 15.1 g of GBL, 3-aminopropyltrimethyl 4.90 g of NMP solution containing 1% by mass of ethoxysilane, 21.0 g of BCS, and 7.00 g of DPM were added and stirred with a magnetic stirrer for 2 hours to obtain a liquid crystal aligning agent (B -3) was obtained.

The liquid crystal aligning agent (A-3) and the liquid crystal aligning agent (B-3) are mixed in an amount of 20:80 to obtain a liquid crystal aligning agent (C-4) having a concentration of 3.5% by mass. It was.

(Example 5)
In a 200 mL Erlenmeyer flask containing a stirrer, 50.0 g of the polyamic acid solution (PAA-1) obtained in Synthesis Example 1 was collected, 48.0 g of NMP, 8.40 g of GBL, 3-aminopropyltrimethyl Add 5.60 g of NMP solution containing 1% by mass of ethoxysilane, 33.6 g of BCS, and 14.4 g of DPM, and stir for 2 hours with a magnetic stirrer to obtain a liquid crystal aligning agent (A -4) was obtained.

In a 200 mL Erlenmeyer flask containing a stir bar, 50.0 g of the polyamic acid solution (PAA-2) obtained in Synthesis Example 2 was collected, 42.0 g of NMP, 1.10 g of GBL, 3-aminopropyltrimethyl 4.90 g of NMP solution containing 1% by mass of ethoxysilane, 29.4 g of BCS, and 12.6 g of DPM were added and stirred for 2 hours with a magnetic stirrer, and the liquid crystal aligning agent (B -4) was obtained.

The liquid crystal aligning agent (A-4) and the liquid crystal aligning agent (B-4) are mixed in an amount of 20:80 to obtain a liquid crystal aligning agent (C-5) having a concentration of 3.5% by mass. It was.

(Example 6)
The liquid crystal aligning agent (A-4) obtained in Example 5 and the liquid crystal aligning agent (B-4) were mixed in an amount to give a mass ratio of 30:70, and the liquid crystal aligning agent having a concentration of 3.5% by mass ( C-6) was obtained.

(Comparative Example 1)
In a 100 mL four-necked flask equipped with a stirrer and a nitrogen inlet tube, 6.79 g (17.8 mmol) of DA-4, 2.17 g (14.3 mmol) of DA-5, and 0.39 g of DA-6 ( 3.61 mmol), 29.2 g of NMP was added, and the mixture was dissolved by stirring while feeding nitrogen. While stirring this diamine solution, 6.25 g (25.0 mmol) of CA-4 was added, and then stirred at 80 ° C. for 5 hours under a nitrogen atmosphere. Next, 2.10 g (10.7 mmol) of CA-2 and 23.9 g of NMP were added, and the mixture was stirred at 40 ° C. for 6 hours while feeding nitrogen, to obtain a polyamic acid solution (PAA-3).

In a 200 mL Erlenmeyer flask containing a stir bar, 30.0 g of this polyamic acid solution (PAA-3) was taken, 68.0 g of NMP and 24.5 g of PB were added, and the mixture was stirred with a magnetic stirrer for 2 hours. A liquid crystal aligning agent (C-7) having a concentration of 6.0% by mass was obtained.

(Synthesis Example 3)
In a 100 mL four-necked flask equipped with a stirrer and a nitrogen introduction tube, 2.11 g (13.9 mmol) of DA-5, 1.41 g (6.94 mmol) of DA-7, and 5.47 g of DA-8 ( 13.9 mmol) was weighed, 27.6 g of NMP was added, and dissolved by stirring while feeding nitrogen. While stirring this diamine solution, 4.34 g (17.3 mmol) of CA-4 was added, followed by stirring at 80 ° C. for 5 hours under a nitrogen atmosphere. Next, 3.40 g (17.3 mmol) of CA-2 and 22.6 g of NMP were added, and the mixture was stirred at 40 ° C. for 6 hours while feeding nitrogen, to obtain a polyamic acid solution (PAA-4).

Into a 200 mL Erlenmeyer flask containing a stir bar, 40.0 g of this polyamic acid solution (PAA-4) was taken, added 8.85 g of acetic anhydride and 6.25 g of pyridine, and reacted at 90 ° C. for 3.5 hours. It was. This reaction solution was poured into 1000 ml of methanol, and the resulting precipitate was filtered off, washed with methanol, and dried under reduced pressure at 100 ° C. to obtain polyimide powder (PI-1). The imidation ratio of this polyimide powder (PI-1) was 78%.

In a 100 mL Erlenmeyer flask containing a stirrer, 2.56 g of this polyimide powder (PI-1) was taken, 18.7 g of NMP was added, and stirred at 70 ° C. for 24 hours to dissolve. -2) was obtained.

(Comparative Example 2)
Into a 100 mL Erlenmeyer flask containing a stir bar, 15.0 g of the polyimide solution (PI-2) obtained in Synthesis Example 3 was fractioned, 9.00 g of NMP and 6.00 g of PB were added, and 2 times with a magnetic stirrer. By stirring for a while, a liquid crystal aligning agent (C-8) having a concentration of 6.0% by mass was obtained.

(Comparative Example 3)
Into a 100 mL Erlenmeyer flask containing a stir bar, 15.0 g of the liquid crystal aligning agent (C-8) obtained in Comparative Example 2 was collected, 8.57 g of NMP and 2.14 g of PB were added, and a magnetic stirrer was added. By stirring for 2 hours, a liquid crystal aligning agent (C-9) having a concentration of 3.5% by mass was obtained.

(Comparative Example 4)
In a 100 mL Erlenmeyer flask containing a stirrer, 15.0 g of the polyimide solution (PI-2) obtained in Synthesis Example 3 was collected, 15.4 g of NMP, 10.7 g of GBL, 7.71 g of BCS, 2.57 g of DPM was added and stirred with a magnetic stirrer for 2 hours to obtain a liquid crystal aligning agent (C-10) having a concentration of 3.5% by mass.

[Evaluation of printability]
The liquid crystal aligning agents obtained in the examples and comparative examples of the present invention were pressure filtered through a membrane filter having a pore size of 1 μm, and a simple printing machine S15 type (manufactured by Nissha Printing Co., Ltd.) was used. It was applied to the chrome surface. Then, after heating for 1 minute on an 80 degreeC hotplate and removing a solvent, it baked for 20 minutes in 230 degreeC IR type oven.

The coating film was visually observed under a sodium lamp, and the case where almost no printing unevenness was observed was evaluated as “good (◯ mark)”, and the case where printing unevenness was observed was evaluated as “bad (× mark)”.

[Evaluation of inkjet coating properties]
The liquid crystal aligning agents obtained in the examples and comparative examples of the present invention were pressure filtered through a membrane filter having a pore diameter of 1 μm, and a glass substrate with an ITO electrode was used using HIS-200 (manufactured by Hitachi Plant Technology). It applied to the ITO surface. Then, after heating for 1 minute on an 80 degreeC hotplate and removing a solvent, it baked for 20 minutes in 230 degreeC IR type oven.

The coating film was observed with a microscope having a magnification of 5 times, and the case where almost no coating unevenness was observed was evaluated as “good (◯ mark)”, and the case where coating unevenness was observed was evaluated as “bad (× mark)”.

Table 2 shows the results of evaluation of printability and inkjet applicability when the liquid crystal aligning agents obtained in Examples and Comparative Examples are used.

The liquid crystal alignment film formed using the liquid crystal aligning agent of the present invention does not use butyl cellosolve, which has been pointed out to be toxic, or reduces the amount of butyl cellosolve used. Therefore, it is a liquid crystal aligning agent excellent in safety. In addition, the liquid crystal aligning agent of the present invention also has high printability and ink jet coatability, as confirmed in the above examples.

Claims

A liquid crystal aligning agent used to form a polyimide film by applying on a substrate and performing a heat treatment,
A polyimide precursor obtained by reacting a tetracarboxylic acid derivative with a diamine component containing at least one diamine selected from the group consisting of compounds represented by the following formulas (YA-1) to (YA-20) And at least one polymer selected from the group consisting of polyimides obtained by imidizing the same, and
A liquid crystal aligning agent comprising: at least one solvent selected from the group consisting of compounds represented by the following formula (1) and the following formula (2).
The liquid crystal aligning agent according to claim 1, wherein the content of the compound represented by the formula (1) in the solvent is 5% by mass or more.
The liquid crystal aligning agent according to claim 1 or 2, wherein the content of the compound represented by the formula (2) in the solvent is 10% by mass or more.
The liquid crystal aligning agent according to any one of claims 1 to 3, wherein the coating is ink jet printing.
The liquid crystal aligning agent according to any one of claims 1 to 3, wherein the coating is flexographic printing.
A liquid crystal alignment film obtained by applying the liquid crystal aligning agent according to any one of claims 1 to 5 to a substrate and subjecting it to a heat treatment.
A liquid crystal display element comprising the liquid crystal alignment film according to claim 6.