KR20160140825A - Liquid crystal alignment agent containing polyamic acid ester-polyamic acid copolymer, and liquid crystal alignment film using same - Google Patents

Abstract

A liquid crystal alignment film having good flatness and excellent afterimage characteristics is provided. A liquid crystal aligning agent containing the component (A) and the component (B).
Component (A): A copolymer having a structural unit represented by formula (1) and a structural unit represented by formula (2).
Component (B): at least one polymer selected from the group consisting of a polyimide precursor having a structural unit represented by the formula (3) and an imidized polymer of the polyimide precursor.
R ₁ is an alkyl group having 1 to 5 carbon atoms; R ₂ is a hydrogen atom or a group having 1 to 10 carbon atoms; and X ₁ , X ₂ and X ₃ are each a tetravalent organic group; Y ₁ , Y ₂ and Y ₃ are divalent organic groups; A ₁ , A ₂ , Z ₁ and Z _{2 each} represent a hydrogen atom or 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, which may have a substituent to be.)

Description

TECHNICAL FIELD The present invention relates to a liquid crystal aligning agent containing a polyamic acid ester-polyamic acid copolymer, and a liquid crystal alignment film using the same. BACKGROUND ART [0002]

The present invention relates to a liquid crystal aligning agent containing a polyamic acid ester-polyamic acid copolymer and a liquid crystal alignment film using the same.

In a liquid crystal display element used for a liquid crystal television, a liquid crystal display, or the like, a liquid crystal alignment film for controlling the alignment state of the liquid crystal is usually formed in the 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, a phase difference plate using a polymerizable liquid crystal, and the like. For example, a liquid crystal display element has a structure in which liquid crystal molecules constituting a liquid crystal layer are sandwiched between liquid crystal alignment films formed on the respective surfaces of a pair of substrates. In a liquid crystal display device, liquid crystal molecules are aligned in a predetermined direction with a pretilt angle by a liquid crystal alignment film, and respond by applying a voltage to electrodes formed between the substrate and the liquid crystal alignment film. As a result, the liquid crystal display element displays a desired image by utilizing the change in orientation caused by the response of the liquid crystal molecules.

As the liquid crystal alignment film, a polyimide-based liquid crystal alignment film obtained by applying a liquid crystal aligning agent mainly composed of a solution of a polyimide precursor such as polyamic acid (polyamic acid) or a soluble polyimide solution to a glass substrate and firing is mainly used have.

In response to demands for suppression of lowering of the contrast of the liquid crystal display element and reduction of the afterimage phenomenon accompanying the fixation of the liquid crystal display element, the liquid crystal alignment film is required to exhibit excellent liquid crystal alignability and stable pretilt angle, , A small residual charge when a direct current voltage is applied, and / or a rapid relaxation of the accumulated residual charge due to a direct current voltage.

In the polyimide-based liquid crystal alignment film, various proposals have been made in order to meet the above-mentioned demands. For example, a liquid crystal aligning agent containing a tertiary amine having a specific structure may be added to a polyamic acid or an imide group-containing polyamic acid as a liquid crystal alignment film having a short time until the afterglow generated by a DC voltage disappears (See, for example, Patent Document 1), a liquid crystal aligning agent containing a soluble polyimide using, as a raw material, a specific diamine compound having a pyridine skeleton or the like (see, for example, Patent Document 2) Has been proposed. In addition, as a liquid crystal alignment film having a high voltage holding ratio and a short time until the after-image caused by the DC voltage disappears, a liquid crystal alignment film containing a compound containing one carboxylic acid group in the molecule, , A compound containing a carboxylic acid anhydride group in a molecule and a compound containing a compound selected from compounds containing one tertiary amino group in the molecule in a small amount (see, for example, Patent Document 3) .

Further, as a liquid crystal alignment film having excellent liquid crystal alignability, high voltage holding ratio, low residual image, excellent reliability, and exhibiting a high pretilt angle, tetracarboxylic acid dianhydride having a specific structure and tetracarboxylic acid having cyclobutane There is known a polyamic acid obtained from an acid dianhydride and a specific diamine compound or a liquid crystal aligning agent containing the imidized polymer (see, for example, Patent Document 4). As a method for suppressing the afterimage due to the AC drive generated in the liquid crystal display element of the transversal electric field driving system, there is a method using a specific liquid crystal alignment film having good liquid crystal alignability and high interaction with liquid crystal molecules 5) has been proposed.

In addition to the above, in recent years, liquid crystal televisions, which are large in size and large in size, have become main subjects, demands for after-images have become stricter, and characteristics capable of enduring long-term use in harsh environments have been demanded. As a result, the liquid crystal alignment film to be used needs to have higher reliability than the conventional one. The properties of the liquid crystal alignment film are required not only to have good initial characteristics but also to maintain good properties even after a long period of exposure at a high temperature, for example.

On the other hand, as the polymer component constituting the polyimide-based liquid crystal aligning agent, the polyamic acid ester has high reliability and does not lower the molecular weight by the heat treatment at the time of imidization, so that the orientation stability and reliability Has been reported (see Patent Document 6). However, the polyamic acid ester has a problem that the volume resistivity is generally high and the relaxation of the residual charge accumulated by the DC voltage is slow.

Japanese Patent Application Laid-Open No. 9-316200 Japanese Patent Application Laid-Open No. 10-104633 Japanese Patent Application Laid-Open No. 8-76128 Japanese Patent Application Laid-Open No. 9-138414 Japanese Patent Application Laid-Open No. 11-38415 Japanese Patent Application Laid-Open No. 2003-26918

As means for improving the disadvantages such as slowness of the residual charge while maintaining the alignment stability and high reliability of the liquid crystal, which is an advantage of the polyamic acid ester, the polyamic acid ester and the polyamic acid having a high relaxation rate of the residual charge are blended It has been confirmed that the liquid crystal aligning element having a liquid crystal alignment film obtained by using such a blend-based liquid crystal aligning agent has a difficulty in the liquid crystal alignability at the time of long-term driving.

As a result of analyzing the above problems, it has been found that fine irregularities are generated on the surface of the liquid crystal alignment film, and that the liquid crystal alignment property is lowered due to the fine irregularities.

The present invention improves the flatness of a liquid crystal alignment film obtained from a blend-based liquid crystal aligning agent of a polyamic acid ester and a polyamic acid, thereby having good liquid crystal alignability and a voltage holding ratio (hereinafter also referred to as VHR) aging resistance, And to provide a liquid crystal aligning agent capable of obtaining a liquid crystal alignment film having a high DC relaxation speed.

As a result of intensive studies, the inventors of the present invention have found that the compatibility of the polyamic acid ester component and the polyamic acid component is low as a cause of the unevenness on the surface of the liquid crystal alignment film obtained by using the above-mentioned blend-based liquid crystal aligning agent. Thus, as a means for improving the unevenness of the film surface, by mixing a copolymer of a polyamic acid ester and a polyamic acid (hereinafter, also referred to as a PAE-PAA copolymer) and a polyamic acid ester or a polyamic acid, While improving the flatness of the liquid crystal alignment film.

That is, the inventors of the present invention found that when a PAE-PAA copolymer is used, both the liquid crystal aligning agent containing a polyamic acid ester and a polyamic acid have satisfactory aging resistance of the liquid crystal alignment property, voltage retention and relaxation speed of the residual charge, A liquid crystal alignment film in which the generation of fine unevenness on the surface of the liquid crystal alignment film is remarkably reduced can be obtained.

The present invention is based on the above findings, and is based on the following items 1 to 10.

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

Component (A): A copolymer having a structural unit represented by the following formula (1) and a structural unit represented by the following formula (2).

[Chemical Formula 1]

(Wherein X ₁ and X ₂ are each independently a tetravalent organic group; Y ₁ and Y ₂ are each independently a divalent organic group; R ₁ is an alkyl group having 1 to 5 carbon atoms; and A ₁ and A ₂ each independently represents a hydrogen atom or 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, which may have a substituent.

Component (B): at least one polymer selected from the group consisting of a polyimide precursor having a structural unit represented by the following formula (3) and an imidized polymer of the polyimide precursor.

(2)

(Wherein X ₃ is a tetravalent organic group, Y ₃ is a divalent organic group, R ₂ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, Z ₁ and Z 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 an alkynyl group having 2 to 10 carbon atoms)

2. The liquid crystal aligning agent according to 1 above, wherein the polyimide precursor of the component (B) is a polyamic acid.

3. The liquid crystal aligning agent according to the above 1, wherein the polyimide precursor of the component (B) is a polyamic acid ester.

Wherein the copolymer has 20 to 80 mol% of the structural unit represented by the formula (1) and 80 to 20 mol% of the structural unit represented by the formula (2) The liquid crystal aligning agent described in any one of < 1 >

5. The liquid crystal aligning agent according to any one of 1 to 4 above, wherein the content of the component (A) and the content of the component (B) is 1/9 to 9/1 in mass ratio.

6. The liquid crystal aligning agent according to any one of 1 to 5 above, which further contains an organic solvent and the total content of the component (A) and the component (B) is 0.5 to 15 mass% with respect to the organic solvent.

7. The liquid crystal aligning agent according to any one of 1 to 6 above, wherein X ₁ , X ₂ and X ₃ are each independently at least one selected from the group consisting of structures represented by the following formulas.

(3)

8. The liquid crystal aligning agent according to any one of 1 to 7 above, wherein Y ₁ , Y ₂ and Y ₃ are each independently at least one selected from the group consisting of structures represented by the following formulas.

[Chemical Formula 4]

9. A liquid crystal alignment film obtained by applying and firing the liquid crystal aligning agent according to any one of 1 to 8 above.

10. A liquid crystal display element having the liquid crystal alignment film as described in 9 above.

According to the present invention, there is provided a liquid crystal aligning agent capable of obtaining a liquid crystal alignment film exhibiting excellent flatness, aging resistance of voltage retention, fast accumulation DC relaxation speed and little decrease in liquid crystal alignability due to long-term driving.

Whether or not the unevenness occurring on the surface of the obtained liquid crystal alignment film can be suppressed by blending the PAE-PAA copolymer with the polyamic acid or the polyamic acid ester in the liquid crystal aligning agent of the present invention is not necessarily clear, .

By approaching the composition of the two components to be blended, it is considered that the unevenness of the surface can be suppressed by improving the compatibility of the two components. On the other hand, it is considered that the two components are not completely mixed and maintained in a somewhat separated state in the film, whereby good liquid crystal alignability, aging resistance of the voltage holding ratio, and relaxation rate of residual charge can be obtained.

It is possible to provide a liquid crystal alignment film having the above three properties by localizing components having good liquid crystal alignability and VHR aging resistance on the film surface side of the liquid crystal alignment film of the present invention and having a high accumulated DC relaxation speed on the substrate side.

Hereinafter, the polyamic acid ester-polyamic acid copolymer (PAE-PAA copolymer) which is the component (A) and the polyimide precursor (polyamic acid ester or polyamic acid) which is contained in the liquid crystal aligning agent of the present invention, Will be described. The liquid crystal aligning agent and the liquid crystal display element of the present invention constituted by containing them will also be described.

≪ Component (A): PAE-PAA copolymer >

The PAE-PAA copolymer used in the present invention is a polyimide precursor for obtaining a polyimide, and is a polymer having a site capable of undergoing an imidization reaction as described below by heating.

[Chemical Formula 5]

(R ₁ is the same as R ₁ in the formula (1).)

The PAE-PAA copolymer contained in the liquid crystal aligning agent of the present invention has a structural unit represented by the following formula (1) and a structural unit represented by the following formula (2).

[Chemical Formula 6]

(7)

In the above formula (1), R ₁ is an alkyl group having 1 to 5 carbon atoms and is preferably a methyl group or an ethyl group from the viewpoint of wetting the glass substrate.

In the formulas (1) and (2), A ₁ and A ₂ each independently represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, Lt; / RTI >

Specific examples of the alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, a t-butyl group, a hexyl group, an octyl group, a decyl group, a cyclopentyl group, a cyclohexyl group and a bicyclohexyl group.

Examples of the alkenyl group include those obtained by substituting one or more CH ₂ -CH ₂ structures existing in the alkyl group with a CH═CH structure, and more specifically, a vinyl group, an allyl group, a 1-propenyl group, Propenyl group, 2-butenyl group, 1,3-butadienyl group, 2-pentenyl group, 2-hexenyl group, cyclopropenyl group, cyclopentenyl group and cyclohexenyl group.

Examples of the alkynyl group include those wherein at least one CH ₂ -CH ₂ structure existing in the alkyl group is substituted with a C≡C structure. More specifically, an ethynyl group, 1-propynyl group, 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, or may form a cyclic structure depending on the substituent. The formation of a ring structure according to a substituent means that a substituent group or a substituent group and a part of the parent (skeleton) bond to form a ring structure.

Examples of the substituent include a halogen group, a hydroxyl group, a thiol group, a nitro group, an aryl group, an organoxy group, an organothio group, an organosilyl group, an acyl group, an ester group, a thioester group, 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.

As the aryl group as a substituent, a phenyl group can be mentioned. These aryl groups may be further substituted with other substituents described above.

The organoxy group as a substituent may represent a structure represented by -O-R. These R may be the same or different and are the alkyl, alkenyl, alkynyl, aryl and the like groups mentioned above. These R may be further substituted with the aforementioned substituents. Specific examples of the organoxy group include a methoxy group, ethoxy group, propyloxy group, butoxy group, pentyloxy group, hexyloxy group, heptyloxy group and octyloxy group.

The organotio group which is a substituent may represent a structure represented by -S-R. As R, examples of the alkyl group, alkenyl group, alkynyl group, aryl group and the like can be mentioned. These R may be further substituted with the aforementioned substituents. Specific examples of the organotitanium group include methylthio group, ethylthio group, propylthio group, butylthio group, pentylthio group, hexylthio group, heptylthio group and octylthio group.

The organosilyl group as a substituent may represent a structure represented by -Si- (R) ₃ . These R may be the same or different and are the alkyl, alkenyl, alkynyl, aryl and the like groups mentioned above. These R may be further substituted with the aforementioned substituents. 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, a hexyldimethylsilyl group, .

The acyl group as a substituent may represent a structure represented by -C (O) -R. As R, examples of the alkyl group, alkenyl group, aryl group, and the like may be mentioned. These R may be further substituted with the aforementioned substituents. Specific examples of the acyl group include a formyl group, an acetyl group, a propionyl group, a butyryl group, an isobutyryl group, a valeryl group, an isovaleryl group, and a benzoyl group.

The ester group as a substituent may represent a structure represented by -C (O) O-R or OC (O) -R. As R, examples of the alkyl group, alkenyl group, alkynyl group, aryl group and the like can be mentioned. These R may be further substituted with the aforementioned substituents.

The thioester group which is a substituent may represent a structure represented by -C (S) O-R or -OC (S) -R. As R, examples of the alkyl group, alkenyl group, alkynyl group, aryl group and the like can be mentioned. These R may be further substituted with the aforementioned substituents.

The phosphoric acid ester group which is a substituent may represent a structure represented by -OP (O) - (OR) ₂ . These R may be the same or different and are the alkyl, alkenyl, alkynyl, aryl and the like groups mentioned above. These R may be further substituted with the aforementioned substituents.

The amide group which is a substituent includes a structure represented by -C (O) NH ₂ , -C (O) NHR, -NHC (O) R, -C (O) N (R) ₂ or -NRC . These R may be the same or different and are the alkyl, alkenyl, alkynyl, aryl and the like groups mentioned above. These R may be further substituted with the aforementioned substituents.

Examples of the aryl group as the substituent include the same aryl groups as those described above. These aryl groups may be further substituted with other substituents described above.

Examples of the alkyl group as the substituent include the same alkyl groups mentioned above. These alkyl groups may be further substituted with other substituents described above.

Examples of the alkenyl group as the substituent include the same alkenyl groups as those described above. This alkenyl group may be further substituted with another substituent as described above.

Examples of the alkynyl group as the substituent include the same alkynyl groups as mentioned above. These alkynyl groups may be further substituted with other substituents described above.

In general, when introducing a bulky structure, 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 an alkyl group having 1 to 5 carbon atoms which may have a substituent is more preferable And a hydrogen atom, a methyl group or an ethyl group is particularly preferable.

In the formulas (1) and (2), when X ₁ and X ₂ are tetravalent organic groups, the structure thereof is not particularly limited, and two or more kinds of them may be mixed. Specific examples of X ₁ and X ₂ include X-1 to X-47 shown below. Among these, from the availability of the 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.

[Chemical Formula 8]

[Chemical Formula 9]

[Chemical formula 10]

(11)

In the formulas (1) and (2), Y ₁ and Y ₂ are divalent organic groups and are not particularly limited. Y ₁ and Y ₂ may be the same or different.

Specific examples of Y ₁ and Y ₂ include the following Y-1 to Y-99. Y-21, Y-22, Y-28, Y-29, Y-30, Y-31 and Y-41 in terms of the availability of monomers. Y-43, Y-64, Y-65, Y-66, Y-68, Y-71, Y-72, Y-98 or Y- , Y-31, Y-72, Y-98 or Y-99 are more preferable.

[Chemical Formula 12]

[Chemical Formula 13]

[Chemical Formula 14]

[Chemical Formula 15]

[Chemical Formula 16]

[Chemical Formula 17]

[Chemical Formula 18]

[Chemical Formula 19]

[Chemical Formula 20]

[Chemical Formula 21]

[Chemical Formula 22]

(23)

In the PAE-PAA copolymer, the proportion of the structural unit represented by the formula (1) is preferably from 10 to 90 mol%, more preferably from 20 to 80 mol%, based on the total structural units.

In the PAE-PAA copolymer, the proportion of the structural unit represented by the formula (2) is preferably from 10 to 90 mol%, more preferably from 20 to 80 mol%, based on the total structural units.

≪ Process for producing PAE-PAA copolymer >

The PAE-PAA copolymer of the present invention is produced by the following method.

A tetracarboxylic acid diester forming X ₁ in the structural unit represented by the above formula (1) and a diamine forming Y ₁ and Y ₂ in the above-mentioned (1) and (2) The reaction is carried out 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 12 hours, A tetracarboxylic acid or its dianhydride for forming X ₂ is added to the structural unit represented by the formula (2), and the mixture is stirred at a temperature of 0 ° C to 50 ° C for 30 minutes to 30 minutes, For 24 hours, preferably 1 to 12 hours.

The organic solvent used in the above reaction is preferably N, N-dimethylformamide, N-methyl-2-pyrrolidone, or γ-butyrolactone from the solubility of the monomer and the polymer. Or more may be mixed and used. The concentration of the polymer is preferably from 1 to 30% by mass, and more preferably from 5 to 20% by mass, from the viewpoint that the precipitation of the polymer hardly occurs and the high molecular weight material is easily obtained.

Examples of the condensing agent include triphenylphosphite, dicyclohexylcarbodiimide, 1-ethyl-3- (3- dimethylaminopropyl) carbodiimide hydrochloride, N, N'-carbonyldiimidazole, dimethoxy- , 3,5-triazinylmethylmorphuronium, O- (benzotriazol-1-yl) -N, N, N ', N'-tetramethyluronium tetrafluoroborate, O- (benzotriazole- (2,3-dihydro-2-thioxo-3-benzoxazolyl) diphenylphosphonate, and the like can be used, Can be used. The addition amount of the condensing agent is preferably 2 to 3 times the molar amount with respect to the tetracarboxylic acid diester.

As the base, tertiary amines such as pyridine and triethylamine can be used. The amount of the base to be added is an amount that is easy to remove, and it is preferably 2 to 4 times the amount of the diamine component from the viewpoint of easily obtaining a high molecular weight material.

The PAE-PAA copolymer obtained as described above can be recovered by precipitating a polymer by injecting the reaction solution into a poor solvent while stirring well. It is also possible to obtain a purified PAE-PAA copolymer powder by conducting precipitation several times, washing with a poor solvent, and drying at room temperature or by heating. Examples of the poor solvent include, but are not limited to, water, methanol, ethanol, hexane, butyl cellosolve, acetone, and toluene.

<Component (B): polyimide precursor: polyamic acid ester or polyamic acid>

The component (B) contained in the liquid crystal aligning agent of the present invention is a polyimide precursor and has a structural unit represented by the following formula (3).

&Lt; EMI ID =

In the formula (3), R ₂ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. Component (B) is the case of the polyamic acid ester, so as the number of carbon atoms in the alkyl group increases, lowering the coating properties of the glass substrate of the polyamic acid ester, from the viewpoint of applying the castle to the substrate, R ₂ is a methyl group or an ethyl group .

In the formula (3), Z ₁ and Z ₂ are each independently a hydrogen atom or 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, to be. Specific examples of the alkyl group having 1 to 10 carbon atoms, the alkenyl group having 2 to 10 carbon atoms or the alkynyl group having 2 to 10 carbon atoms include the same ones as the specific examples of A ₁ and A ₂ .

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, or may form a cyclic structure depending on the substituent. The formation of a ring structure according to a substituent means that a substituent or a substituent and a part of the parent skeleton are bonded to form a ring structure.

Examples of such a substituent include the same ones as the specific examples of the substituent in A ₁ and A ₂ above.

In the formula (3), X ₃ is not particularly limited as long as it is a tetravalent organic group. Specific examples of X _{3 include} the same ones as the specific examples of X ₁ and X ₂ .

In the formula (3), Y ₃ is not particularly limited as long as it is a divalent organic group. Specific examples of Y _{3 include} the same ones as the specific examples of Y ₁ and Y ₂ .

&Lt; Production method of component (B): Polyamic acid>

When the component (B) is a polyamic acid, the polyamic acid is prepared by the following method.

In the structural unit represented by the formula (3), a tetracarboxylic acid or its anhydride and the second diamine for forming, Y ₃ to form a X _3, the presence of an organic solvent, -20 ℃ ~ 150 ℃, preferably Is prepared by polycondensation reaction at 0 캜 to 50 캜 for 30 minutes to 24 hours, preferably 1 to 12 hours.

The organic solvent used in the above reaction is preferably N, N-dimethylformamide, N-methyl-2-pyrrolidone, or γ-butyrolactone from the solubility of the monomer and the polymer. Or more may be mixed and used. The concentration of the polymer is preferably from 1 to 30% by mass, and more preferably from 5 to 20% by mass, from the viewpoint that the precipitation of the polymer hardly occurs and the high molecular weight material is easily obtained.

The polyamic acid thus obtained can be recovered by precipitating a polymer by injecting the reaction solution into a poor solvent while stirring well. It is also possible to obtain a purified polyamic acid powder by conducting precipitation several times, washing with a poor solvent, and then drying at room temperature or by heating. Examples of the poor solvent include, but are not limited to, water, methanol, ethanol, hexane, butyl cellosolve, acetone, and toluene.

&Lt; Production method of component (B): Polyamic acid ester &gt;

When the component (B) is a polyamic acid ester, the polyamic acid ester is produced by the following method.

(1) Production from polyamic acid

The polyamic acid ester can be produced by esterifying the polyamic acid prepared as described above. Concretely, 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 to 4 hours Can be manufactured.

The esterification agent is preferably one which can be easily removed by purification, and examples thereof include N, N-dimethylformamide dimethylacetal, N, N-dimethylformamide diethyl acetal, N, N-dimethylformamide dipropyl acetal, N, N-dimethylformamide dineopentylbutyl acetal, N, N-dimethylformamide di-t-butyl acetal, 1-methyl-3-p-tolyltriazine, , 1-propyl-3-p-tolyltriazine, and 4- (4,6-dimethoxy-1,3,5-triazin-2-yl) -4-methylmorpholinium chloride. The amount of the esterifying agent to be added is preferably 2 to 6 molar equivalents relative to 1 mol of the repeating unit of the polyamic acid.

Examples of the organic solvent include N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, gamma -butyrolactone, N, N-dimethylformamide, N, N-dimethylacetamide , Dimethyl sulfoxide or 1,3-dimethyl-imidazolidinone. When the solvent solubility of the polyimide precursor is high, methyl ethyl ketone, cyclohexanone, cyclopentanone, or 4-hydroxy-4-methyl-2-pentanone can be used.

These solvents may be used alone or in combination. Further, a solvent that does not dissolve the polyimide precursor may be used in combination with the solvent insofar as the resulting polyimide precursor does not precipitate. In addition, the moisture in the solvent inhibits the polymerization reaction and further causes hydrolysis of the resulting polyimide precursor. Therefore, it is preferable that the solvent is dehydrated and dried.

The solvent to be used in the above reaction is preferably N, N-dimethylformamide, N-methyl-2-pyrrolidone or γ-butyrolactone from the solubility of the polymer, May be used.

The concentration of the polymer at the time of production is preferably from 1 to 30% by mass, more preferably from 5 to 20% by mass, from the viewpoint that the precipitation of the polymer is hardly caused and the high molecular weight material is easily obtained.

(2) When produced by the reaction of a tetracarboxylic acid diester dichloride with a diamine

The polyamic acid ester is obtained by reacting a tetracarboxylic acid dichloride forming X ₃ and a diamine forming Y ₃ with a diamine in the structural unit represented by the above formula (3) at a temperature of -20 ° C to 150 ° C , Preferably 0 ° C to 50 ° C, for 30 minutes to 24 hours, preferably 1 to 4 hours.

As the base, pyridine, triethylamine, 4-dimethylaminopyridine and the like can be used, but pyridine is preferable for the reaction to proceed mildly. The amount of the base to be added is preferably 2 to 4 times the molar amount of the tetracarboxylic acid diester dichloride in view of easy removal and high molecular weight.

The solvent used in the above reaction is preferably N-methyl-2-pyrrolidone or? -Butyrolactone from the viewpoint of the solubility of the monomer and the polymer, and they may be used alone or in combination of two or more.

The concentration of the polymer at the time of production is preferably from 1 to 30% by mass, more preferably from 5 to 20% by mass, from the viewpoint that the precipitation of the polymer is hardly caused and the high molecular weight material is easily obtained. In order to prevent the hydrolysis of the tetracarboxylic acid diester dichloride, it is preferable that the solvent used for the production of the polyamic acid ester is dehydrated as much as possible, and it is preferable to prevent the mixture of the ambient air in a nitrogen atmosphere .

(3) In the case of production from a tetracarboxylic acid diester and a diamine

The polyamic acid ester is obtained by reacting a tetracarboxylic acid diester forming X ₃ with a diamine forming Y ₃ in a structural unit represented by the above formula (3) in the presence of a condensing agent, a base, Deg.] C to 150 [deg.] C, preferably 0 [deg.] C to 100 [deg.] C for 30 minutes to 24 hours, preferably 3 to 15 hours.

Examples of the condensing agent include triphenylphosphite, dicyclohexylcarbodiimide, 1-ethyl-3- (3- dimethylaminopropyl) carbodiimide hydrochloride, N, N'-carbonyldiimidazole, dimethoxy- , 3,5-triazinylmethylmorphuronium, O- (benzotriazol-1-yl) -N, N, N ', N'-tetramethyluronium tetrafluoroborate, O- (benzotriazole- (2,3-dihydro-2-thioxo-3-benzoxazolyl) diphenylphosphonate, and the like can be used, Can be used. The amount of the condensing agent to be added is preferably 2 to 3 times the amount of the tetracarboxylic acid diester.

As the base, tertiary amines such as pyridine and triethylamine can be used. The amount of the base to be added is preferably 2 to 4 times the amount of the diamine component in view of easy removal and high molecular weight.

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

Among the above-mentioned methods for producing polyamic acid esters, polyamic acid esters having a high molecular weight can be obtained with good reproducibility, and the production method of the above (3) is particularly preferable.

The solution of the polyamic acid ester obtained as described above can be precipitated by injecting it into a poor solvent while stirring well. After the precipitation is repeated several times, it is washed with a poor solvent and then heated or dried at room temperature to obtain a purified polyamic acid ester powder. Examples of the poor solvent include, but are not limited to, water, methanol, ethanol, hexane, butyl cellosolve, acetone, and toluene.

<Liquid Crystal Aligner>

The content of the component (A) and the content of the component (B) in the liquid crystal aligning agent of the present invention are preferably 1/9 to 9/1, more preferably 2/8 to 8/1, 8/2.

The liquid crystal aligning agent of the present invention contains a polyamic acid ester or polyamic acid represented by the formula (3) as the component (B).

When the component (B) is a polyamic acid ester, the weight average molecular weight of the polyamic acid ester is preferably 5,000 to 300,000, more preferably 10,000 to 200,000. The number average molecular weight is preferably 2,500 to 150,000, more preferably 5,000 to 30,000.

When the component (B) is a polyamic acid, the weight average molecular weight of the polyamic acid is preferably 10,000 to 305,000, more preferably 20,000 to 210,000. The number average molecular weight is preferably 5,000 to 152,500, and more preferably 10,000 to 105,000.

The liquid crystal aligning agent of the present invention is in the form of a solution in which the PAE-PAA copolymer and a polyamic acid ester or polyamic acid are dissolved in an organic solvent. When each component is synthesized in an organic solvent, the reaction solution itself may be obtained, or the reaction solution may be appropriately diluted with another solvent. When each component is obtained as a powder, it may be dissolved in an organic solvent to form a solution.

The content (concentration) of the polymer component in the liquid crystal aligning agent of the present invention can be appropriately changed depending on the setting of the thickness of the polyimide film to be formed. In order to form a uniform and defect-free coating film, , The content of the polymer component is preferably 0.5% by mass or more, more preferably 15% by mass or less, and still more preferably 1% by mass to 10% by mass from the viewpoint of the storage stability of the solution. In this case, it is also possible to prepare a polymer-rich solution in advance and to dilute the liquid-crystal aligning agent from such a concentrated solution. The concentration of the concentrated solution of the polymer component is preferably 10 to 30% by mass, more preferably 10 to 15% by mass. The polymer component powder may be dissolved in an organic solvent to prepare a solution. The heating temperature is preferably 20 占 폚 to 150 占 폚, and particularly preferably 20 占 폚 to 80 占 폚.

The organic solvent contained in the liquid crystal aligning agent of the present invention is not particularly limited as long as the polymer component is uniformly dissolved. Specific examples thereof include N, N-dimethylformamide, N, N-diethylformamide, N, N-dimethylacetamide, N-methyl- , N-methylcaprolactam, 2-pyrrolidone, N-vinyl-2-pyrrolidone, dimethylsulfoxide, dimethylsulfone,? -Butyrolactone, 1,3-dimethyl-imidazolidinone, N, N-dimethylpropanamide, and the like. These may be used alone or in combination of two or more. In addition, even if the solvent can not dissolve the polymer component uniformly, it may be mixed with the organic solvent as long as the solvent does not precipitate the polymer.

The liquid crystal aligning agent of the present invention may contain, in addition to the organic solvent for dissolving the polymer component, a solvent for improving the film uniformity when the liquid crystal aligning agent is applied to the substrate. Such a solvent generally uses a solvent having a lower surface tension than the organic solvent. Specific examples thereof include ethyl cellosolve, butyl cellosolve, butyl cellosolve acetate, ethyl carbitol, butyl carbitol, ethyl carbitol acetate, ethylene glycol, 1-methoxy-2-propanol, 1- 2-propanol, 1-phenoxy-2-propanol, propylene glycol monoacetate, propylene glycol diacetate, propylene glycol-1-monomethyl ether-2-acetate, propylene glycol- Lactic acid methyl ester, lactic acid ethyl ester, lactic acid n-propyl ester, lactic acid n-butyl ester, lactic acid isoamyl ester, lactic acid ethyl ester-2-acetate, dipropylene glycol, 2- (2- ethoxypropoxy) propanol, Esters and the like. These solvents may be used in combination of two or more.

As long as the effects of the present invention are not impaired, the liquid crystal aligning agent of the present invention may be added to various kinds of compounds such as a compound which improves film thickness uniformity and surface smoothness when a liquid crystal aligning agent is applied, a silane coupling agent, It may contain an additive.

Examples of the compound that improves film thickness uniformity and surface smoothness include a fluorine-based surfactant, a silicon-based surfactant, and a nonionic surface-active agent.

More specifically, for example, FFP (registered trademark) EF301, EF303, EF352 (manufactured by Tohchem Products), Megapack (registered trademark) F171, F173, R-30 (Trade name) manufactured by Asahi Kasei Co., Ltd.), FC430, FC431 (manufactured by Sumitomo 3M Company), Asahi Guard (registered trademark) AG710, Sapron (registered trademark) S-382, SC101, SC102, SC103, SC104, SC105, have.

The proportion of these surfactants to be used is preferably 0.01 to 2 parts by mass, more preferably 0.01 to 1 part by mass based on 100 parts by mass of the resin component contained in the liquid crystal aligning agent.

The silane coupling agent is added for the purpose of improving the adhesion between the substrate to which the liquid crystal aligning agent is applied and the liquid crystal alignment film formed thereon. For example, the following compounds are exemplified as specific examples, but the present invention is not limited thereto .

Aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3- (2-aminoethyl) aminopropyltrimethoxysilane, 3- Amine-based silane coupling agents such as phenylaminopropyltrimethoxysilane, 3-triethoxysilyl-N- (1,3-dimethyl-butylidene) propylamine and 3-aminopropyldiethoxymethylsilane; Vinyltrimethoxysilane, vinyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (2-methoxyethoxy) silane, vinylmethyldimethoxysilane, vinyltriacetoxysilane, vinyltriisopropoxysilane, allyltrimethoxysilane, p Vinyl silane coupling agents such as styryltrimethoxysilane; 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2- (3,4 - epoxycyclohexyl) ethyl trimethoxysilane; Methacrylic silane coupling agents such as 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, and 3-methacryloxypropyltriethoxysilane. Ring agent; Acrylic silane coupling agents such as 3-acryloxypropyltrimethoxysilane; A ureido-based silane coupling agent such as 3-ureidopropyltriethoxysilane; Sulfide-based silane coupling agents such as bis (3- (triethoxysilyl) propyl) disulfide, and bis (3- (triethoxysilyl) propyl) tetrasulfide; Mercapto-based silane coupling agents such as 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane and 3-octanoylthio-1-propyltriethoxysilane; Isocyanate-based silane coupling agents such as 3-isocyanatepropyltriethoxysilane and 3-isocyanatepropyltrimethoxysilane; Aldehyde-based silane coupling agents such as triethoxysilylbutylaldehyde; Carbamate-based silane coupling agents such as triethoxysilylpropylmethyl carbamate and (3-triethoxysilylpropyl) -t-butylcarbamate.

If the amount of the silane coupling agent is too large, the unreacted portion may adversely affect the liquid crystal alignability. If the silane coupling agent is too small, the silane coupling agent may not exhibit the effect of adhesion, so that the amount is preferably 0.01 to 5.0 wt% More preferably 0.1 to 1.0% by weight.

In the liquid crystal alignment film of the present invention, an imidization accelerator may be added to efficiently imidize the PAE-PAA copolymer or polyamic acid ester when the coating film is baked.

&Lt; Liquid crystal alignment film &

The liquid crystal aligning agent of the present invention is a film obtained by applying the liquid crystal aligning agent to a substrate, drying it if necessary, and then firing it. 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. For example, a plastic substrate such as an acrylic substrate or a polycarbonate substrate can be used in addition to a glass substrate. In the production of a liquid crystal display device, when the liquid crystal aligning agent of the present invention is used, it is preferable to use a substrate on which an ITO (Indium Tin Oxide) electrode for liquid crystal driving is formed to form a liquid crystal alignment film. In the case of manufacturing a reflective liquid crystal display device, an opaque substrate such as a silicon wafer may be used only for a substrate on one side, and a material for reflecting light such as aluminum may be used for the electrode in this case.

As a method of applying the liquid crystal aligning agent of the present invention on a substrate, for example, screen printing, offset printing, flexographic printing or inkjet method can be mentioned. Other coating methods include a dipping method, a roll coater method, a slit coater method, a spinner method, and a spraying method, and they may be used depending on the purpose.

Usually, it is dried at 50 ° C to 120 ° C for 1 minute to 10 minutes and then at 150 ° C to 300 ° C for 5 minutes to 120 minutes in order to sufficiently remove the contained organic solvent. The thickness of the coated film after firing is not particularly limited, but if it is too thin, the reliability of the liquid crystal display element may deteriorate. Therefore, it is 5 to 300 nm, preferably 10 to 200 nm.

Examples of a method for aligning the obtained liquid crystal alignment film include a rubbing method and an optical alignment treatment method.

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

Specific examples of the photo-alignment treatment method include a method of irradiating the surface of the coating film with radiation deflected in a predetermined direction and, if necessary, further subjecting the coating film to a heat treatment at a temperature of 150 to 250 ° C to give a liquid crystal aligning ability . As the radiation, ultraviolet rays and visible rays having a wavelength of 100 to 800 nm can be used. Of these, ultraviolet rays having a wavelength of 100 to 400 nm are preferable, and those having a wavelength of 200 to 400 nm are particularly preferable.

In addition, in order to improve the liquid crystal alignment property, the coating film substrate may be irradiated with radiation while heating at 50 to 250 ° C. The irradiation dose of the radiation is preferably 1 to 10,000 mJ / cm2, and particularly preferably 100 to 5,000 mJ / cm2. The liquid crystal alignment film thus produced can stably orient liquid crystal molecules in a certain direction.

<Liquid crystal display element>

In the liquid crystal display element of the present invention, a substrate having a liquid crystal alignment film attached thereto from the liquid crystal aligning agent of the present invention is obtained by the above-described technique, and then a liquid crystal cell is produced by a known method to form a liquid crystal display element.

An example of a method of manufacturing a liquid crystal display element is as follows. First, a pair of substrates on which a liquid crystal alignment film is formed are prepared, and they are bonded with a spacer having a size of preferably 1 to 30 mu m, more preferably 2 to 10 mu m, And the periphery is fixed with a sealant. Subsequently, liquid crystal is injected between the substrates and sealed. The liquid crystal sealing method is not particularly limited, and examples thereof include a vacuum method in which liquid crystal is injected after reducing the pressure in the produced liquid crystal cell, and a dropping method in which sealing is performed after liquid crystal is dropped.

Example

Hereinafter, the present invention will be described in more detail by way of examples. The present invention is not limited to these examples.

The structures and abbreviations of the main compounds used in Examples and Comparative Examples are as follows.

<Carboxylic acid>

X-1: 2,4-bis (methoxycarbonyl) cyclobutane-1,3-dicarboxylic acid

X-2: 1,2,3,4-Cyclobutane tetracarboxylic acid dianhydride

X-3: pyromellitic acid dianhydride

X-4: 3,3 ', 4,4'-biphenyltetracarboxylic acid dianhydride

<Diamine>

Y-1: bis (4-aminophenoxy) methane

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

Y-3: 1,3-bis (4-aminophenoxy) propane

Y-4: 4,4'-diaminodiphenylamine

Y-5: 4- (2- (methylamino) ethyl) aniline

Y-6: 1,3-bis (4-aminophenetyl) urea

Y-7: 3,5-diaminobenzoic acid

<Condenser>

DBOP: diphenyl (2,3-dihydro-2-thioxo-3-benzoxazolyl) phosphonate

<Silane coupling agent>

Z-1: 3-glycidoxypropyltriethoxysilane

<Structural Formula>

(25)

(26)

The evaluation methods performed in the present embodiment and the comparative example are shown below.

[Viscosity]

The viscosity of the polyamic acid solution or polyamic acid ester solution was measured by using an E-type viscometer TVE-22H (manufactured by Toki Industries Co., Ltd.), a sample amount of 1.1 ml, a cone rotor TE-1 (1 占 34 ' Respectively.

[Solid content concentration]

The solid content concentration of the polyamic acid solution or the polyamic acid ester solution was calculated in the following manner.

Approximately 1.1 g of a polyamic acid solution or polyamic acid ester solution was taken in an aluminum cup No. 2 (manufactured by Asuzon Co., Ltd.) with a handle attached thereto and heated in an oven DNF 400 (manufactured by Yamato Scientific Co., Ltd.) for 2 hours at a temperature of 200 ° C. Thereafter, it was left at room temperature for 5 minutes, and the weight of the solid content remaining in the aluminum cup was measured. The solid content concentration was calculated from the value of the solid content weight and the value of the original solution weight.

[Molecular Weight]

The molecular weight of the polyamic acid solution or the polyamic acid ester solution is measured by a GPC (room temperature gel permeation chromatography) apparatus, and the number average molecular weight (hereinafter also referred to as Mn) and the weight average molecular weight (Hereinafter, also referred to as Mw).

GPC apparatus: manufactured by Shodex Corp. (GPC-101)

Column: manufactured by Shodex Co., Ltd. (serial of KD803, KD805)

Column temperature: 50 ° C

30 mmol / l of lithium bromide-hydrate (LiBr.H ₂ O), 30 mmol / l of phosphoric anhydride crystal (o-phosphoric acid), 30 ml of tetrahydrofuran (THF) 10 ml / l)

Flow rate: 1.0 ml / min

Standard sample for calibration curve: TSK standard polyethylene oxide (weight average molecular weight (Mw): about 900,000, 150,000, 100,000 and 30,000) manufactured by Tosoh Corporation and polyethylene glycol (peak top molecular weight (Mp): about 12,000, 4,000, and 1,000). In order to avoid peak overlapping, two samples of samples mixed with four types of 900,000, 100,000, 12,000, and 1,000 and three samples of 150,000, 30,000, and 4,000 were separately measured.

[Flatness of film]

In the Examples and Comparative Examples, the flatness of the polyimide film was measured as follows.

Shape image measurement was carried out by dynamic force mode (DFM) using an L-trace device manufactured by S-AIA Nanotechnology. The SI-DF40 was used for the cantilever, and the shape image obtained under the measurement conditions shown below was firstly corrected, and then the value of the average surface roughness was calculated.

Scanning Area: 10 x 10 mu m

Amplitude Decay Rate: -0.128

I gain: 0.0444

P gain: 0.0488

A gain: 10

S gain: 10

Scanning frequency: 2.0 Hz

[Aging resistance of voltage retention rate]

Evaluation was conducted using the liquid crystal cell manufactured by the following method.

(Production of liquid crystal cell)

The liquid crystal alignment treatment agent was filtered with a filter of 1.0 占 퐉 and then spin-coated on a glass substrate with a transparent electrode attached thereto. The resultant was dried on a hot plate at 80 占 폚 for 5 minutes and then baked at 230 占 폚 for 30 minutes, A polyimide film was obtained. This polyimide film was subjected to ultrasonic irradiation for 1 minute in pure water after rubbing with a rayon cloth (roll diameter 120 mm, rotation speed 1000 rpm, moving speed 20 mm / sec, indentation amount 0.4 mm) And dried for 10 minutes.

Two sheets of the thus obtained liquid crystal alignment film-attached substrates were prepared, spacers of 4 mu m were provided on the liquid crystal alignment film surface of one of the substrates, and the rubbing directions of the two substrates were anti-parallel. And the periphery was sealed, and an empty cell having a cell gap of 4 탆 was produced. A liquid crystal (MLC-2041, manufactured by Merck) was injected into this cell under vacuum at room temperature, and the injection port was sealed to obtain an anti-parallel liquid crystal cell.

[Aging resistance of voltage retention rate]

The liquid crystal cell manufactured by the above method was aged in an oven at 60 ° C. for 48 hours under an LED light source (1000 cd). The voltage retention rate before and after aging was measured, and when it was 85% or more before aging and when it was 50% or more after aging, it was evaluated as &amp; cir &amp;

(Measurement conditions of voltage holding ratio)

A voltage of 1 V was applied for 60 占 퐏 and a voltage after 100 占 퐏 was measured to calculate a variation from the initial value as a voltage holding ratio. The temperature of the liquid crystal cell was measured at 60 캜.

[Accumulated DC damping rate] and [Liquid crystal orientation property]

Evaluation was conducted using the liquid crystal cell manufactured by the following method.

(Production of liquid crystal cell)

Initially, a substrate with an electrode attached thereto was prepared. The substrate is a glass substrate having a size of 30 mm x 50 mm and a thickness of 0.7 mm. On the substrate, an ITO electrode having a front pattern constituting the counter electrode as the first layer is formed. On the first layer counter electrode, a SiN (silicon nitride) film formed by the CVD method is formed as the second layer. The thickness of the second-layer SiN film is 500 nm and functions as an interlayer insulating film. On the second-layer SiN film, pixel electrodes on the combs formed by patterning the ITO film as the third layer are disposed, and two pixels, i.e., the first pixel and the second pixel, are formed. The size of each pixel is 10 mm in length and 5 mm in width. At this time, the first layer counter electrode and the third layer pixel electrode are electrically insulated by the action of the second layer SiN film.

The third layer pixel electrode has a comb-like shape formed by arranging a plurality of elongated electrode elements bent at the center portion. The width of each electrode element in the width direction is 3 占 퐉, and the interval between the electrode elements is 6 占 퐉. Since the pixel electrode forming each pixel is constituted by arranging a plurality of bent and elongated electrode elements at the center portion, the shape of each pixel is not a rectangle shape but is bent at the center portion like the electrode element , And has a shape similar to a bold character. Each pixel is divided into upper and lower portions with the central bent portion as a boundary, and has a first region on the upper side of the bent portion and a second region on the lower side.

When the first region and the second region of each pixel are compared with each other, the electrode elements of the pixel electrodes constituting the first region and the second region are different from each other. In other words, when the rubbing direction of a liquid crystal alignment film to be described later is taken as a reference, the electrode elements of the pixel electrodes are formed so as to form an angle of +10 degrees (clockwise) in the first region of the pixel, The element is formed so as to form an angle (clockwise direction) of -10 degrees. That is, in the first region and the second region of each pixel, the direction of rotation (inflation / switching) of the liquid crystal induced (induced) by the application of a voltage between the pixel electrode and the counter electrode in the substrate plane So that it is in the opposite direction.

Next, the obtained liquid crystal aligning agent was filtered with a filter having a pore diameter of 1.0 탆, and then a glass substrate having a prepared substrate on which the electrode was adhered and a columnar spacer having a thickness of 4 탆 and having an ITO film formed on the back thereof was spin- . Subsequently, the substrate was dried on a hot plate at 100 DEG C for 5 minutes and then baked at 230 DEG C for 20 minutes to obtain a polyimide film on each substrate as a coating film having a thickness of 60 nm. This polyimide film was subjected to rubbing (roll diameter: 120 mm, rotation speed: 500 rpm, moving speed: 30 mm / sec, indentation amount: 0.3 mm) by rayon cloth in a predetermined rubbing direction, And dried at 80 DEG C for 10 minutes.

Thereafter, using the two kinds of substrates having the liquid crystal alignment film attached thereto, the rubbing directions were combined so as to be anti-parallel, leaving the liquid crystal injection ports and sealing the periphery to prepare empty cells with a cell gap of 3.6 mu m. A liquid crystal (MLC-2041, manufactured by Merck) was vacuum-injected into the empty cell at room temperature, and then the injection port was sealed to obtain an anti-parallel alignment liquid crystal cell. The resulting liquid crystal cell constitutes an FFS mode liquid crystal display element. Thereafter, the obtained liquid crystal cell was heated at 110 DEG C for 1 hour, left for one night, and used for evaluation.

[Accumulation DC relaxation rate (time of disappearance of afterimage)]

Evaluation of the accumulated DC relaxation speed (disappearance time of residual image) was performed using the following optical system and the like.

The prepared liquid crystal cell was placed between two polarizing plates arranged so that the polarization axis thereof was orthogonal to each other. The LED backlight was turned on in the voltage unapplied state and the arrangement angle of the liquid crystal cell was adjusted so that the luminance of the transmitted light was minimized.

Next, a V-T curve (voltage-transmittance curve) was measured while applying an AC voltage with a frequency of 30 Hz to this liquid crystal cell, and an AC voltage having a relative transmittance of 23% was calculated as a drive voltage.

In the afterimage evaluation, a DC voltage of 30 V was applied so that the relative transmittance was 23%, the liquid crystal cell was driven while a DC voltage of 1 V was applied at the same time, and the device was driven for 30 minutes. Thereafter, the application of the direct current voltage was stopped with the applied direct current voltage value at 0 V, and the device was further driven for 20 minutes in this state.

The after-image evaluation was performed by defining "O" when the relative transmittance was restored to 25% or less and "X" when the relative transmittance was 25% or more until 20 minutes elapsed after the application of the DC voltage was stopped. The residual image evaluation according to the above-described method was performed under the temperature condition in which the temperature of the liquid crystal cell was 23 占 폚.

[Liquid crystal alignment property (after-image evaluation by long-term driving)]

An AC voltage having a relative transmittance of 100% at a frequency of 30 Hz was applied for 100 hours under a constant temperature environment of 60 占 폚. Thereafter, the pixel electrode and the counter electrode of the liquid crystal cell were short-circuited, and left at room temperature for one day.

After leaving the liquid crystal cell, the liquid crystal cell was placed between two polarizers arranged so that the polarization axis thereof was orthogonal to each other. The backlight was turned on in the voltage unapplied state and the arrangement angle of the liquid crystal cell was adjusted so that the luminance of the transmitted light was minimized. The rotation angle when the liquid crystal cell was rotated from the angle at which the second area of the first pixel was darkest to the angle at which the first area became darkest was calculated as the angle?. Similarly, in the second pixel, the second region and the first region were compared and the same angle? Was calculated. Then, the average value of the angles? Of the first and second pixels was calculated as the angle? Of the liquid crystal cell. A case where the value of the angle? Of the liquid crystal cell was 0.2 degrees or less was defined as?, And a case where the value of 0.2 degrees or more was defined as x.

(Synthesis Example 1) A polyamic acid ester solution

174.9 g (672.0 mmol) of X-1 was added to a 5000 ml four-necked flask equipped with a stirrer, and 3351 g of N-methyl-2-pyrrolidone was added and dissolved by stirring. Then 148.7 g (1470 mmol) of triethylamine and 180.8 g (700.0 mmol) of Y-3 were added and dissolved by stirring.

While this solution was stirred, 563.5 g (1470 mmol) of DBOP was added, and further 460.4 g of N-methyl-2-pyrrolidone was added, followed by stirring at room temperature for 12 hours to obtain a solution of the polyamic acid ester. The viscosity of the polyamic acid ester solution at 25 캜 was 61.1 mPa..

This polyamic acid ester solution was poured into methanol (29280 g), and the resulting precipitate was separated by filtration. The precipitate was washed with methanol, and then dried under reduced pressure at a temperature of 100 ° C to obtain a powder of polyamic acid ester. The molecular weight of this polyamic acid ester was Mn = 13,400 and Mw = 34,600.

1.77 g of the polyamic acid ester powder was taken in a 100 ml Erlenmeyer flask containing an agitator, and 27.7 g of N-methyl-2-pyrrolidone was added and dissolved by stirring at room temperature for 18 hours. Subsequently, 0.02 g of Z-1 and 9.85 g of butyl cellosolve were added and stirred for 2 hours to obtain a polyamic acid ester solution having a solid content concentration of 4.34 mass%.

(Synthetic Example 2) A polyamic acid solution

9.56 g (37.0 mmol) of Y-3 was added to a 100-ml four-necked flask equipped with a stirrer, 74.6 g of N-methyl-2-pyrrolidone was added and dissolved with stirring while nitrogen was being fed. While stirring the diamine solution, 6.89 g (35.2 mmol) of X-2 was further added, and 18.6 g of N-methyl-2-pyrrolidone was further added and the mixture was stirred at 23 ° C for 5 hours under a nitrogen atmosphere to obtain a polyamic acid Solution. The viscosity of the polyamic acid solution at 25 캜 was 436 mPa.. The molecular weight of this polyamic acid was Mn = 15,400 and Mw = 41,700.

10.3 g of this polyamic acid solution was collected into a 100 ml Erlenmeyer flask containing an agitator, 18.7 g of N-methyl-2-pyrrolidone, 0.02 g of Z-1 and 9.68 g of butyl cellosolve were added, The mixture was stirred with a stirrer for 2 hours to obtain a polyamic acid solution having a solid content concentration of 4.00 mass%.

(Synthesis Example 3) A PAE-PAA copolymer solution

In a 200 ml four-necked flask equipped with a stirrer, 3.90 g (15.0 mmol) of X-1 was added, and 59.7 g of N-methyl-2-pyrrolidone was added and dissolved by stirring. 3.24 g (32.0 mmol) of triethylamine and 5.17 g (20.0 mmol) of Y-3 were then added and dissolved by stirring.

While stirring the solution, 11.50 g (30.0 mmol) of DBOP was added, and 12.8 g of N-methyl-2-pyrrolidone was further added, followed by stirring at room temperature for 12 hours. Thereafter, 1.00 g (4.00 mmol) of diphenyl phosphate and 0.94 g (4.80 mmol) of X-2 were added, and then 12.8 g of N-methyl-2-pyrrolidone was added and stirred at room temperature for 12 hours , A solution of PAE-PAA copolymer was obtained. The viscosity of this polyamic acid ester solution at 25 캜 was 36.1 mPa s.

This polyamic acid ester solution was poured into methanol (666 g), and the resulting precipitate was separated by filtration. The precipitate was washed with methanol and dried under reduced pressure at a temperature of 60 ° C to obtain a PAE-PAA copolymer powder. The molecular weight of this PAE-PAA copolymer was Mn = 5,900 and Mw = 12,200.

6.16 g of the polyamic acid-polyamic acid ester powder was taken in a 100-ml Erlenmeyer flask containing an agitator, and 65.2 g of N-methyl-2-pyrrolidone was added and dissolved by stirring at room temperature for 18 hours. Subsequently, 0.06 g of Z-1 and 23.3 g of butyl cellosolve were added and stirred for 2 hours to obtain a polyamic acid-polyamic acid ester solution having a solid content concentration of 6.13 mass%.

(Synthesis Example 4) A PAE-PAA copolymer solution

To a 100 ml four-necked flask equipped with a stirrer, 2.47 g (9.50 mmol) of X-1 was added, and 55.4 g of N-methyl-2-pyrrolidone was added and dissolved by stirring. Then 2.11 g (20.9 mmol) of triethylamine and 4.91 g (19.0 mmol) of Y-3 were added and dissolved by stirring.

While this solution was stirred, 7.28 g (19.0 mmol) of DBOP was added, and 11.9 g of N-methyl-2-pyrrolidone was further added, followed by stirring at room temperature for 12 hours. Thereafter, 0.95 g (3.80 mmol) of diphenyl phosphate and 1.75 g (8.93 mmol) of X-2 were added, followed by 11.9 g of N-methyl-2-pyrrolidone and the mixture was stirred at room temperature for 7 hours , A solution of PAE-PAA copolymer was obtained. The viscosity of this polyamic acid ester solution at 25 캜 was 32.7 mPa..

This polyamic acid ester solution was poured into methanol (591 g), and the resulting precipitate was separated by filtration. The precipitate was washed with methanol and dried under reduced pressure at a temperature of 60 ° C to obtain a PAE-PAA copolymer powder. The molecular weight of this PAE-PAA copolymer was Mn = 7,000 and Mw = 13,200.

1.46 g of the polyamic acid-polyamic acid ester powder was taken in a 100-ml Erlenmeyer flask containing an agitator, 20.4 g of N-methyl-2-pyrrolidone was added and dissolved by stirring at room temperature for 18 hours. Subsequently, 0.01 g of Z-1 and 7.3 g of butyl cellosolve were added and stirred for 2 hours to obtain a polyamic acid-polyamic acid ester solution having a solid content concentration of 4.60 mass%.

(Synthetic Example 5) A polyamic acid solution

In a 100 ml four-necked flask equipped with a stirrer, 2.21 g (9.60 mmol) of Y-1 was added, and 65.2 g of N-methyl-2-pyrrolidone was added and stirred to dissolve while nitrogen was being fed. While stirring the diamine solution, 2.47 g (8.40 mmol) of X-4 was added, and the mixture was stirred at 23 占 폚 for 4 hours under a nitrogen atmosphere. Thereafter, 2.87 g (14.4 mmol) of Y-4 was added and after confirming that it was dissolved, 2.80 g (14.3 mmol) of X-2 was added. Further, 27.95 g of N-methyl-2-pyrrolidone was added and stirred for 30 hours to obtain a polyamic acid solution. The viscosity of the polyamic acid solution at 25 캜 was 118 mPa.. The molecular weight of this polyamic acid was Mn = 15,600 and Mw = 36,800.

11.6 g of N-methyl-2-pyrrolidone, 0.02 g of Z-1, and 9.20 g of butyl cellosolve were added to a 100 ml Erlenmeyer flask containing a stirrer, 16.6 g of this polyamic acid solution was added, The mixture was stirred with a stirrer for 2 hours to obtain a polyamic acid solution having a solid content concentration of 4.47 mass%.

(Synthesis Example 6) A polyamic acid solution

In a 100 ml four-necked flask equipped with a stirrer, 1.80 g (12.0 mmol) of Y-5 was taken, 76.6 g of N-methyl-2-pyrrolidone was added and dissolved with stirring while nitrogen was being supplied. 2.29 g (10.5 mmol) of X-3 was added while stirring the diamine solution, and the mixture was stirred at 23 占 폚 for 2 hours under a nitrogen atmosphere. Then, 5.37 g (18.0 mmol) of Y-6 was added and after confirming that it was dissolved, 3.59 g (18.3 mmol) of X-2 was added. Further, 19.1 g of N-methyl-2-pyrrolidone was added and stirred for 4 hours to obtain a polyamic acid solution. The viscosity of the polyamic acid solution at 25 캜 was 332 mPa.. The molecular weight of this polyamic acid was Mn = 16,600 and Mw = 38,000.

13.8 g of the polyamic acid solution was collected in a 100 ml Erlenmeyer flask containing an agitator, and 13.8 g of N-methyl-2-pyrrolidone, 0.02 g of Z-1 and 9.22 g of butyl cellosolve were added, The mixture was stirred with a stirrer for 2 hours to obtain a polyamic acid solution having a solid content concentration of 4.50% by mass.

(Synthetic Example 7) A polyamic acid solution

79.7 g (400 mmol) of Y-4 and 15.2 g (100 mmol) of Y-7 were placed in a 2000 ml four-necked flask equipped with a stirrer, and 1403 g of N-methyl- And dissolved with stirring while nitrogen was supplied. While stirring the diamine solution, 144.2 g (490 mmol) of X-4 was added, and 350.8 g of N-methyl-2-pyrrolidone was further added and the mixture was stirred at 23 DEG C for 3 hours under a nitrogen atmosphere to obtain a polyamic acid solution &Lt; / RTI &gt; The viscosity of this polyamic acid solution at 25 캜 was 4656 mPa s. The molecular weight of this polyamic acid was Mn = 11,000 and Mw = 27,100.

93.8 g of this polyamic acid solution was put in a 200 ml Erlenmeyer flask containing a stirrer, 45.3 g of N-methyl-2-pyrrolidone, 0.11 g of Z-1 and 46.4 g of butyl cellosolve were added, The mixture was stirred with a stirrer for 2 hours to obtain a polyamic acid solution having a solid concentration of 6.02 mass%.

(Synthesis Example 8) A PAE-PAA copolymer solution

To a 200 ml four-necked flask equipped with a stirrer, 6.01 g (23.1 mmol) of X-1 was added, and 114.3 g of N-methyl-2-pyrrolidone was added and dissolved by stirring. Then, 5.10 g (50.4 mmol) of triethylamine, 4.18 g (21.0 mmol) of Y-4 and 4.84 g (21.0 mmol) of Y-1 were added and dissolved by stirring.

While stirring the solution, 17.7 g (46.2 mmol) of DBOP was added, and further 24.5 g of N-methyl-2-pyrrolidone was added, followed by stirring at room temperature for 12 hours. Thereafter, 2.10 g (8.40 mmol) of diphenyl phosphate and 3.94 g (18.1 mmol) of X-3 were added, followed by 24.5 g of N-methyl-2-pyrrolidone and the mixture was stirred at room temperature for 5 hours , A solution of PAE-PAA copolymer was obtained. The viscosity of this PAE-PAA copolymer solution at a temperature of 25 ° C was 47.7 mPa · s.

This PAE-PAA copolymer solution was introduced into 2-propanol (1242 g), and the obtained precipitate was separated by filtration. The precipitate was washed with methanol and dried under reduced pressure at a temperature of 60 ° C to obtain a PAE-PAA copolymer powder. The molecular weight of this PAE-PAA copolymer was Mn = 8,800 and Mw = 16,300.

1.80 g of this PAE-PAA copolymer powder was taken in a 100 ml Erlenmeyer flask containing an agitator, and 28.2 g of N-methyl-2-pyrrolidone was added and dissolved by stirring at room temperature for 12 hours. Subsequently, 0.02 g of Z-1 and 10.0 g of butyl cellosolve were added and stirred for 2 hours to obtain a PAE-PAA copolymer solution having a solid content concentration of 4.11 mass%.

(Synthesis Example 9) A PAE-PAA copolymer solution

In a 200 ml four-necked flask equipped with a stirrer, 7.81 g (30.0 mmol) of X-1 was added, 110.9 g of N-methyl-2-pyrrolidone was added and dissolved by stirring. Then, 6.48 g (64.8 mmol) of triethylamine, 3.98 g (20.0 mmol) of Y-4 and 4.89 g (20.0 mmol) of Y-2 were added and dissolved by stirring.

While stirring this solution, 23.0 g (60.0 mmol) of DBOP was added, and 23.8 g of N-methyl-2-pyrrolidone was further added, followed by stirring at room temperature for 12 hours. Thereafter, 2.00 g (8.00 mmol) of diphenyl phosphate and 2.01 g (9.20 mmol) of X-3 were added, followed by 23.8 g of N-methyl-2-pyrrolidone and the mixture was stirred at room temperature for 5 hours A solution of PAE-PAA copolymer was obtained. The viscosity of this PAE-PAA copolymer solution at 25 캜 was 60.9 mPa s.

This PAE-PAA copolymer solution was introduced into 2-propanol (2000 g), and the obtained precipitate was separated by filtration. The precipitate was washed with methanol and dried under reduced pressure at a temperature of 60 ° C to obtain a PAE-PAA copolymer powder. The molecular weight of this PAE-PAA copolymer was Mn = 8,400 and Mw = 16,200.

1.81 g of this PAE-PAA copolymer powder was taken in a 100 ml Erlenmeyer flask containing a stirrer, 28.4 g of N-methyl-2-pyrrolidone was added, and the mixture was stirred and dissolved at room temperature for 12 hours. Subsequently, 0.02 g of Z-1 and 10.1 g of butyl cellosolve were added and stirred for 2 hours to obtain a PAE-PAA copolymer solution having a solid content concentration of 4.09% by mass.

(Synthesis Example 10) A solution of PAE-PAA copolymer

In a 200 ml four-necked flask equipped with a stirrer, 7.81 g (30.0 mmol) of X-1 was added, and 112.0 g of N-methyl-2-pyrrolidone was added and dissolved by stirring. Then, 6.48 g (64.8 mmol) of triethylamine, 3.19 g (16.0 mmol) of Y-4 and 5.86 g (24.0 mmol) of Y-2 were added and dissolved by stirring.

While stirring this solution, 23.0 g (60.0 mmol) of DBOP was added, and 24.0 g of N-methyl-2-pyrrolidone was further added, followed by stirring at room temperature for 12 hours. Thereafter, 2.00 g (8.00 mmol) of diphenyl phosphate and 2.01 g (9.20 mmol) of X-3 were added, and then 24.0 g of N-methyl-2-pyrrolidone was added and stirred at room temperature for 5 hours , A solution of PAE-PAA copolymer was obtained. The viscosity of this PAE-PAA copolymer solution at a temperature of 25 캜 was 71.4 mPa..

This PAE-PAA copolymer solution was introduced into 2-propanol (2000 g), and the obtained precipitate was separated by filtration. The precipitate was washed with methanol and dried under reduced pressure at a temperature of 60 ° C to obtain a PAE-PAA copolymer powder. The molecular weight of this PAE-PAA copolymer was Mn = 8,600 and Mw = 17,700.

1.85 g of this PAE-PAA copolymer powder was taken in a 100 mL Erlenmeyer flask containing 29.0 g of stirring, and 29.0 g of N-methyl-2-pyrrolidone was added and dissolved by stirring at room temperature for 12 hours. Subsequently, 0.02 g of Z-1 and 10.3 g of butyl cellosolve were added and stirred for 2 hours to obtain a PAE-PAA copolymer solution having a solid content concentration of 3.96 mass%.

&Lt; Comparative Example 1 &

A solution obtained by mixing the polyamic acid ester solution obtained in Synthesis Example 1 and the polyamic acid solution obtained in Synthesis Example 5 at a solid weight ratio of 50:50 was filtered with a filter having a size of 1.0 탆 and then transferred onto a glass substrate Spin-coated. Thereafter, the film was left on a hot plate at a temperature of 30 占 폚 for 10 minutes, and fired at 230 占 폚 for 20 minutes to obtain a polyimide film having a thickness of 100 nm. The average surface roughness of this polyimide film was measured and found to be 7.4 nm. Since the surface of the polyimide film had many irregularities, it was not suitable for the production of a liquid crystal cell.

&Lt; Comparative Example 2 &

A polyimide film having a thickness of 100 nm was obtained in the same manner as in Comparative Example 1 except that the polyamic acid solution obtained in Synthesis Example 2 and the polyamic acid solution obtained in Synthesis Example 5 were used. The average surface roughness of the polyimide film was 0.4 nm.

[Evaluation of aging resistance of voltage holding ratio], [accumulation DC relaxation speed] and [liquid crystal alignability] were evaluated after manufacturing a liquid crystal cell by the method described in the column of [Production of liquid crystal cell] above. The results are shown in Table 2.

&Lt; Example 1 &gt;

A polyimide film having a thickness of 100 nm was obtained in the same manner as in Comparative Example 1 except that the PAE-PAA copolymer solution obtained in Synthesis Example 3 and the polyamic acid solution obtained in Synthesis Example 5 were used. The average surface roughness of the polyimide film was 0.6 nm.

After the liquid crystal cell was produced in the same manner as in Comparative Example 1, evaluation was made of [aging resistance of voltage retentivity], [accumulation DC relaxation speed] and [liquid crystal alignability].

Liquid crystal cells were produced in the same manner as in Examples 2 to 7 below and evaluated in the same manner. The results are summarized in Table 2.

&Lt; Example 2 &gt;

A polyimide film having a thickness of 100 nm was obtained in the same manner as in the comparative example except that the PAE-PAA copolymer solution obtained in Synthesis Example 4 and the polyamic acid solution obtained in Synthesis Example 5 were used. The average surface roughness of the polyimide film was 0.4 nm.

&Lt; Example 3 &gt;

A polyimide film having a thickness of 100 nm was obtained in the same manner as in the comparative example except that the PAE-PAA copolymer solution obtained in Synthesis Example 3 and the polyamic acid solution obtained in Synthesis Example 6 were used. The average surface roughness of the polyimide film was 0.6 nm.

<Example 4>

A polyimide film having a thickness of 100 nm was obtained in the same manner as in the comparative example except that the PAE-PAA copolymer solution obtained in Synthesis Example 3 and the polyamic acid solution obtained in Synthesis Example 7 were used. The average surface roughness of this polyimide film was 0.7 nm.

&Lt; Example 5 &gt;

A polyimide film having a thickness of 100 nm was obtained in the same manner as in the comparative example except that the polyamic acid ester solution obtained in Synthesis Example 1 and the PAE-PAA copolymer solution obtained in Synthesis Example 8 were used. The average surface roughness of this polyimide film was 0.2 nm.

&Lt; Example 6 &gt;

A polyimide film having a thickness of 100 nm was obtained in the same manner as in the comparative example except that the polyamic acid ester solution obtained in Synthesis Example 1 and the PAE-PAA copolymer solution obtained in Synthesis Example 9 were used. The average surface roughness of this polyimide film was 0.2 nm.

&Lt; Example 7 &gt;

A polyimide film having a thickness of 100 nm was obtained in the same manner as in the comparative example except that the polyamic acid ester solution obtained in Synthesis Example 1 and the PAE-PAA copolymer solution obtained in Synthesis Example 10 were used. The average surface roughness of this polyimide film was 0.2 nm.

The compositions of the liquid crystal aligning agents used in the above Examples and Comparative Examples are summarized in Table 1. The numerical values in parentheses represent the ratio (molar ratio) of each carboxylic acid or each diamine in the case where two kinds of carboxylic acid or diamine are used to obtain each component.

As shown in Table 2, the liquid crystal alignment films formed using the liquid crystal aligning agents of Examples 1 to 7 including the PAE-PAA copolymer were found to have excellent flatness.

Further, it was found that the liquid crystal alignment film of the present invention was excellent in the aging resistance of the voltage holding ratio, shortened in time until the after-image caused by the DC voltage disappeared, and had excellent liquid crystal alignability.

On the other hand, the liquid crystal alignment film formed using the liquid crystal aligning agent of Comparative Example 1 had insufficient flatness and the liquid crystal alignment film obtained from the liquid crystal aligning agent of Comparative Example 2 had aging resistance of the voltage retention ratio, It was found to be inferior in orientation.

From the above, it was found that the liquid crystal aligning agent of the present invention can form a liquid crystal alignment film having flatness, excellent electric characteristics, and good liquid crystal alignability.

Industrial availability

The liquid crystal alignment film formed using the liquid crystal aligning agent of the present invention has flatness, excellent voltage maintaining ratio aging resistance, accumulated DC relaxation speed and good liquid crystal alignment property. The liquid crystal aligning agent of the present invention not only improves the liquid crystal alignability but also improves the voltage retention rate and the electrical characteristics such as the residual DC voltage through the reduction of fine unevenness on the surface of the obtained liquid crystal alignment film. As a result, it is widely useful for TN devices, STN devices, TFT liquid crystal devices, and vertically aligned liquid crystal display devices.

The entire contents of the specification, claims, and abstract of Japanese Patent Application No. 2014-077226 filed on April 3, 2014 are incorporated herein by reference and are hereby incorporated by reference.

Claims (10)

A liquid crystal aligning agent characterized by containing the following components (A) and (B).
Component (A): A copolymer having a structural unit represented by the following formula (1) and a structural unit represented by the following formula (2).
[Chemical Formula 1]

(Wherein X ₁ and X ₂ are each independently a tetravalent organic group; Y ₁ and Y ₂ are each independently a divalent organic group; R ₁ is an alkyl group having 1 to 5 carbon atoms; and A ₁ and A ₂ each independently represents a hydrogen atom or 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, which may have a substituent.
Component (B): at least one polymer selected from the group consisting of a polyimide precursor having a structural unit represented by the following formula (3) and an imidized polymer of the polyimide precursor.
(2)

(Wherein X ₃ is a tetravalent organic group, Y ₃ is a divalent organic group, R ₂ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, Z ₁ and Z 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 an alkynyl group having 2 to 10 carbon atoms) The method according to claim 1,
Wherein the polyimide precursor of the component (B) is a polyamic acid. The method according to claim 1,
Wherein the polyimide precursor of the component (B) is a polyamic acid ester. 4. The method according to any one of claims 1 to 3,
Wherein the copolymer has 20 to 80 mol% of the structural unit represented by the formula (1) and 80 to 20 mol% of the structural unit represented by the formula (2), with respect to the total structural units of the copolymer. 5. The method according to any one of claims 1 to 4,
Wherein the content of the component (A) and the component (B) is 1/9 to 9/1 in mass ratio. 6. The method according to any one of claims 1 to 5,
Wherein the content of the component (A) and the component (B) is 0.5 to 15% by mass with respect to the organic solvent. 7. The method according to any one of claims 1 to 6,
X ₁ , X ₂ and X ₃ are each independently at least one selected from the group consisting of structures represented by the following formulas:
(3)

8. The method according to any one of claims 1 to 7,
Y ₁ , Y ₂ and Y ₃ are each independently at least one selected from the group consisting of structures represented by the following formulas:
[Chemical Formula 4]

A liquid crystal alignment film obtained by applying and firing the liquid crystal aligning agent according to any one of claims 1 to 8. A liquid crystal display element having the liquid crystal alignment film according to claim 9.