KR20140141620A - Polyimide-based liquid crystal aligning agent, liquid crystal alignment film, and liquid crystal display element - Google Patents

Abstract

(X₁ 은 4 가의 유기기이고, Y₁ 은 2 가의 유기기이다. X₂ 는 4 가의 유기기이고, Y₂ 는 2 가의 유기기이며, R₁ 은 탄소수 1 ∼ 5 의 알킬기이다. A₁ 및 A₂ 는 각각 독립적으로 수소 원자, 또는 치환기를 가져도 되는 탄소수 1 ∼ 10 의 알킬기, 알케닐기 혹은 알키닐기이다.)Provided is a liquid crystal alignment treatment agent which forms a liquid crystal alignment film having good rubbing resistance and high imidization rate, good printability, and excellent voltage retention and storage charge.
A liquid crystal alignment treatment agent characterized by containing a soluble polyimide represented by the following formula (1) and a polyamic acid ester represented by the following formula (2).
[Chemical Formula 1]

(And X ₁ is a tetravalent organic group, Y ₁ is a divalent an organic group. X ₂ is a tetravalent organic group, Y ₂ is a divalent organic group, R ₁ is an alkyl group having a carbon number of ₁ ~ 5. A 1 And A ₂ are each independently a hydrogen atom, or an alkyl, alkenyl or alkynyl group having 1 to 10 carbon atoms which may have a substituent.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal alignment agent, a liquid crystal alignment film, and a liquid crystal display element,

The present invention relates to a polyimide-based liquid crystal alignment treatment agent, a liquid crystal alignment film using the same, and a liquid crystal display element.

A liquid crystal display element is a display element which has a structure in which liquid crystal molecules are sandwiched between liquid crystal alignment films formed on a substrate and which responds to the liquid crystal molecules.

The liquid crystal alignment film plays an important role in controlling the alignment direction of the liquid crystal molecules and the pretilt angle in an arbitrary state.

The liquid crystal alignment film is generally produced by applying a so-called " rubbing treatment ", in which a surface of a polyimide film formed on a substrate is rubbed by applying pressure to the surface thereof with rayon, nylon or the like. The alignment direction of the liquid crystal molecules is determined by the rubbing process.

As means for increasing the pretilt angle of the liquid crystal, a means for introducing an alkyl group having a long chain into the structure of the polyimide forming the liquid crystal alignment film is known (see, for example, Patent Document 1).

As a means for forming a polyimide film on a substrate, there is a method of applying a solution of polyamic acid or the like and imidizing it on a substrate and a method of applying a solution of a soluble polyimide. Among them, a method using a soluble polyimide solution can form a polyimide film having excellent characteristics in the case of using a liquid crystal alignment film, even if the film is sintered at a relatively low temperature. On the other hand, since the strength of the formed film is low, There is a problem that scratches and peeling of the film are liable to occur.

As a means for applying a polymer solution onto a substrate in the production of a liquid crystal alignment film, flexography is widely used industrially at present. However, since the soluble polyimide solution having a high imidation rate is poor in printing properties such as bleaching phenomenon, studies have been required to use soluble polyimides having a low imidization ratio, etc. (see, for example, Patent Document 2).

Further, when a long-chain alkyl group is introduced into the structure of the soluble polyimide in order to give a large pretilt angle to the liquid crystal, the printability tends to deteriorate.

As a means for improving the printability of the polymer solution to the substrate, a method of adding a solvent such as butyl cellosolve is known (see, for example, Patent Document 3).

However, soluble polyimides generally have low solubility as compared with polyamic acid and the like, so that a large amount of a solvent such as butyl cellosolve can not be used.

Japanese Patent Application Laid-Open No. 2-282726 Japanese Patent Application Laid-Open No. 9-297312 Japanese Patent Application Laid-Open No. 2-037324

It is an object of the present invention to provide a liquid crystal alignment film having excellent rubbing resistance and to provide a liquid crystal alignment film excellent in printability even if the imidization ratio of soluble polyimide is high and also has electrical characteristics such as voltage holding ratio (VHR) And to provide a polyimide-based liquid crystal alignment treatment agent containing excellent and soluble polyimide.

The inventors of the present invention have conducted studies to improve the printing characteristics at the time of forming a film without deteriorating the characteristics and electrical characteristics of the polyimide-based liquid crystal alignment treatment agent containing the soluble polyimide described above. As a result, , It is found that a liquid crystal alignment treatment containing a polyamic acid ester having a specific structure can achieve this purpose.

That is, a liquid crystal alignment treatment agent containing a polyamic acid ester having a specific structure together with a soluble polyimide having a specific structure does not cause whitening at the time of forming a coating film even when the imidization ratio is high, It is possible to provide a liquid crystal alignment film having a good anti-rubbing property of the coating film. Further, it was found that the resulting liquid crystal alignment film has excellent electrical characteristics, particularly excellent voltage holding ratio and accumulated charge (RDC), which are not available in the prior art.

That is, the present invention has been made based on the above-described findings, and has the following points.

1. A liquid crystal alignment treatment agent characterized by containing a soluble polyimide represented by the following formula (1) and a polyamic acid ester represented by the following formula (2).

[Chemical Formula 1]

In the formula (2), X ₂ is a tetravalent organic group, Y ₂ is a divalent organic group, R ₁ is a tetravalent organic group, and Y ₁ is a divalent organic group. ₁ is an alkyl group having 1 to 5 carbon atoms, A ₁ and A ₂ are each independently a hydrogen atom or an alkyl group, alkenyl group or alkynyl group having 1 to 10 carbon atoms which may have a substituent.

2. The liquid crystal alignment treating agent according to 1, wherein R ₁ in the formula (2) is a methyl group.

3. The liquid crystal alignment treatment agent according to 1 or 2 above, wherein X ₁ and X ₂ in formulas (1) and (2) are each independently at least one selected from the structures represented by the following formulas.

(2)

4. The liquid crystal alignment treatment agent according to any one of the above-mentioned 1 to 3, wherein in the formula (2), X ₂ has the following structure having an aromatic ring.

(3)

5. The liquid crystal alignment treatment agent according to any one of 1 to 3 above, wherein X ₁ in the formula (1) has an aliphatic structure or an alicyclic structure.

6. The liquid crystal alignment treating agent according to any one of 1 to 5 above, wherein the polyamic acid ester has a weight average molecular weight of 5,000 to 200,000.

7. The liquid crystal alignment treatment agent according to any one of 1 to 6 above, wherein the soluble polyimide has an imidization ratio of 50% or more and a weight average molecular weight of 5,000 to 200,000.

8. The method according to any one of 1 to 7 above, wherein the ratio of the content of the soluble polyimide to the content of the polyamic acid ester (content of the soluble polyimide / content of the polyamic acid ester) in the mass ratio is 1/9 to 9/1 A liquid crystal alignment treatment agent according to claim 1.

9. The polyimide resin composition according to any one of claims 1 to 8, wherein the content of the soluble polyimide and the total amount of the polyamic acid ester is 0.5 to 15% by mass based on 100% by mass of the organic solvent, and the organic solvent dissolves the soluble polyimide and the polyamic acid ester The liquid crystal alignment treatment agent according to any one of the preceding claims.

10. The liquid crystal alignment treating agent as described in 9 above, wherein the organic solvent contains at least one member selected from the group consisting of N-methyl-pyrrolidone, N-ethyl-pyrrolidone and? -Butyrolactone.

11. The liquid crystal alignment treatment agent according to any one of 1 to 10 above, further comprising a solvent.

12. The liquid crystal alignment treatment agent according to 11 above, wherein the solvent is butyl cellosolve.

13. A liquid crystal alignment film obtained by applying the liquid crystal alignment treatment agent according to any one of 1 to 12 above and firing.

14. The liquid crystal alignment film as described in 13 above, wherein the coating film obtained by coating and firing the liquid crystal alignment treatment agent has a thickness of 5 to 300 nm.

15. A liquid crystal display element comprising the liquid crystal alignment film according to 13 or 14 above.

According to the liquid crystal alignment treatment agent of the present invention, even when the imidization ratio of the soluble polyimide is high, a liquid crystal alignment film having good printing properties and good rubbing resistance of the coating film without causing whitening during coating film formation can be obtained. In addition, the obtained liquid crystal alignment film has excellent electrical characteristics, and especially excellent voltage-retention ratio and accumulated charge (RDC).

In the present invention, since the polarity and lipid solubility are close to the soluble polyimide by using the polyamic acid ester, they are not two-layered as described below, and even at the interface in contact with the liquid crystal, they exist at the concentration of the polyamic acid ester .

On the other hand, when a polyamic acid is used in place of the polyamic acid ester contained in the liquid crystal alignment treatment agent of the present invention, the whitening phenomenon at the time of forming the coating film is improved, but the obtained liquid crystal alignment film has a voltage holding ratio, In terms of the characteristics of the device.

The reason why the polyamic acid is used instead of the polyamic acid ester is not necessarily clear. However, when polyamic acid is used, since polarity and lipid solubility differ from soluble polyimide, Is a two-layer system in which a soluble polyimide component and a polyamic acid component are located in the lower layer.

≪ Soluble polyimide &

The soluble polyimide used in the present invention has a structure represented by the following formula (1).

[Chemical Formula 4]

In the above formula (1), X ₁ is a tetravalent organic group.

Represents a preferred embodiment of X _1, it can be given X-1 ~ X-46 as described below. From retrieving 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 or X-32.

Among them, when X ₁ has an aliphatic structure or an alicyclic structure, the obtained liquid crystal alignment film is preferable because it has high voltage holding ratio characteristics. X ₁ having a preferable aliphatic structure is preferably X-1, X-16 or X-19, and particularly preferably X-1 or X-19.

[Chemical Formula 5]

[Chemical Formula 6]

(7)

[Chemical Formula 8]

In the formula (1), Y ₁ is a divalent organic group and is not particularly limited. Specific preferred examples of Y ₁ include the following Y-1 to Y-97.

Y ₁ , Y ₂ , Y ₂ , Y ₂ , Y ₂ , Y ₁ , Y ₂ , Y 3, Y-41, Y-42, Y-43, Y-44, Y-45, Y-46, Y-48, Y-61, Y- 73, Y-74, Y-75 and Y-98 are more preferable, and diamine compounds having these structures are preferable.

Y ₁ is Y-76, Y-77, Y-78, Y-79, Y-80, Y-81, Y-82, Y-83, Y-84, Y-85, In the case of the Y-89, Y-90, Y-91, Y-92, Y-93, Y-94, Y-95, Y- Can be increased.

[Chemical Formula 9]

[Chemical formula 10]

(11)

[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]

The soluble polyimide used in the present invention is obtained by imidizing a polyimide precursor by a known method. Polyimide precursor refers to polyamic acid or polyamic acid ester.

When polyamic acid is used in the imidization, dehydration ring closure of the polyamic acid is carried out, and when polyamic acid ester is used, the polyamic acid ester is heated and closed.

Among them, in the present invention, a method of dehydrating ring closure of polyamic acid is more preferable because it can raise the imidization rate.

The imidization rate of the soluble polyimide in the present invention can be controlled by controlling the amount of catalyst in the imidization reaction, the reaction temperature, and the reaction time. In the present invention, since a polyimide having a high imidization ratio can be used, the imidization ratio is preferably 50% or more, more preferably 70% or more, and particularly preferably 80% or more. Among them, the imidization ratio is more preferably 80 to 90%.

Polyamic acid is obtained by a known method by the reaction of a diamine component with a tetracarboxylic acid dianhydride.

The polyamic acid ester may be prepared by reacting a diamine component and a tetracarboxylic acid diester dichloride in the presence of a base or by reacting a tetracarboxylic acid diester and a diamine in the presence of a suitable condensing agent or base .

<Polyamic acid ester>

The polyamic acid ester used in the present invention has a structure represented by the following formula (2).

[Chemical Formula 22]

In the above formula (2), R ₁ is an alkyl group having 1 to 5 carbon atoms.

The polyamic acid ester has a higher temperature at which imidization proceeds as the number of carbon atoms in the alkyl group increases. Therefore, R ₁ is preferably an alkyl group having 1 or 2 carbon atoms, particularly a methyl group, from the viewpoint of easiness of imidization by heat.

In the formula (2), X ₂ have the same definitions as Y _1, each of the Y ₂ has the formula (1) X _1, and the formula (2) in the formula (1). Among them, in the case where X ₂ in the formula (2) has an aromatic structure, the obtained liquid crystal alignment film is preferable because it has high voltage holding ratio characteristics. Examples of preferable X ₂ having an aromatic structure include X-26 to X-45 described above, and X-26 is particularly preferable.

In the formula (2), A ₁ and A ₂ are each independently a hydrogen atom or an alkyl, alkenyl or alkynyl group having 1 to 10 carbon atoms which may have a substituent.

Specific examples of the alkyl group having 1 to 10 carbon atoms which may have a substituent include a methyl group, ethyl group, propyl group, butyl group, t-butyl group, hexyl group, octyl group, decyl group, cyclopentyl group, cyclohexyl group, Cyclohexyl group, and the like.

Examples of the alkenyl group having 1 to 10 carbon atoms which may have a substituent include those wherein at least one CH ₂ -CH ₂ structure present in the alkyl group is substituted with a CH = CH structure. More specifically, Butenyl group, a 2-pentenyl group, a 2-hexenyl group, a cyclopropenyl group, a cyclopentenyl group, a cyclohexenyl group, etc., .

Examples of the alkynyl group having 1 to 10 carbon atoms which may have a substituent include those wherein at least one CH ₂ -CH ₂ structure present in the alkyl group is substituted with a C≡C structure. More specifically, an ethynyl group, A 1-propynyl group, a 2-propynyl group, and the like.

Each of A ₁ and A ₂ is preferably a hydrogen atom, a methyl group, an ethyl group, a vinyl group or an allyl group, and more preferably a hydrogen atom or a methyl group.

The alkyl group, alkenyl group and alkynyl group may have a substituent group when the number of carbon atoms is 1 to 10 as a whole, and may form a ring structure by a substituent. In addition, the formation of a ring structure by a substituent means that a substituent group or a substituent group and a part of the parent skeleton are bonded to form a ring structure.

The polyamic acid ester represented by the formula (2) can be obtained by reacting any of the tetracarboxylic acid derivatives represented by the following formulas (6) to (8) with a diamine compound represented by the formula (9).

(23)

&Lt; EMI ID =

(Wherein X ₂ , Y ₂ , R ₁ , A ₁ and A ₂ are each as defined above)

The polyamic acid ester represented by the above formula (2) can be synthesized by any of the methods (A) to (C) described below.

(A) When synthesized with polyamic acid

The polyamic acid ester can be synthesized by esterifying a polyamic acid obtained from a tetracarboxylic acid dianhydride and a diamine.

(25)

Specifically, the reaction can be carried out by reacting the polyamic acid and the esterifying agent in the presence of an organic solvent at -20 to 150 ° C, preferably 0 to 50 ° C, for 30 minutes to 24 hours, preferably 1 to 4 hours have.

The esterifying agent is preferably one which can be easily removed by purification. Examples of the esterifying agent 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. Among them, N, N-dimethylformamide dimethylacetal is preferable.

The amount of the esterifying agent to be added is preferably 2 to 6 molar equivalents and more preferably 3 to 4 molar equivalents relative to 1 mol of the repeating unit of the polyamic acid.

The organic solvent used in the reaction is preferably N, N-dimethylformamide, N-methyl-2-pyrrolidone or? -Butyrolactone in view of the solubility of the polymer, May be mixed and used.

The concentration of the polymer in the synthesis 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 hardly occurs and the high molecular weight material is easily obtained.

(B) when synthesized by the reaction of a tetracarboxylic acid diester dichloride with a diamine

Polyamic acid esters can be synthesized from tetracarboxylic acid diester dichloride and diamine.

(26)

Specifically, the tetracarboxylic acid diester dichloride and the diamine are reacted in the presence of a base and an organic solvent at -20 to 150 ° C, preferably 0 to 50 ° C for 30 minutes to 24 hours, For 4 hours.

As the base, pyridine, triethylamine, 4-dimethylaminopyridine and the like can be used, but pyridine is preferable because the reaction proceeds mildly.

The amount of the base to be added is preferably 2 to 4 times, more preferably 2 to 3 times as much as the tetracarboxylic acid diester dichloride from the viewpoint of easy removal and high molecular weight.

The organic solvent to be used in the 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 in the synthesis is preferably from 1 to 30 mass%, more preferably from 5 to 20 mass%, from the viewpoint that 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, the organic solvent used for the synthesis of the polyamic acid ester is desirably dehydrated as much as possible, and it is preferable to prevent the external air from being mixed in a nitrogen atmosphere Do.

(C) When a polyamic acid is synthesized from a tetracarboxylic acid diester and a diamine

The polyamic acid ester can be synthesized by polycondensation of a tetracarboxylic acid diester and a diamine.

(27)

Specifically, the tetracarboxylic acid diester and diamine are reacted in the presence of a condensing agent, a base and an organic solvent at 0 to 150 ° C, preferably 0 to 100 ° C, for 30 minutes to 24 hours, preferably 3 To &lt; / RTI &gt; 15 hours.

Examples of the condensate include triphenylphosphite, dicyclohexylcarbodiimide, 1-ethyl-3- (3- dimethylaminopropyl) carbodiimide hydrochloride, N, N'-carbonyldiimidazole, dimethoxy- (Benzotriazol-1-yl) -N, N, N ', N'-tetramethyluronium tetrafluoroborate, O- (2,3-dihydro-2-thioxo-3-benzoxazolyl) diphenylphosphonate, and the like can be used, for example, by using N, N, N ', N'-tetramethyluronium hexafluorophosphite, .

The amount of the condensing agent to be added is preferably 2 to 3 times by mole, more preferably 2 to 2.5 times by mole, based on the tetracarboxylic acid diester.

As the base, tertiary amines such as pyridine and triethylamine can be used.

The amount of the base to be added is an amount which is easy to remove and is preferably 2 to 4 times, more preferably 2 to 3 times, the amount of the diamine component from the viewpoint of easily obtaining a high molecular weight material.

As the organic solvent to be used in the reaction, N-methyl-2-pyrrolidone and? -Butyrolactone are preferable 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.

In addition, 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 amount of the Lewis acid to be added is preferably 0 to 1.0 times by mole, more preferably 0.2 to 0.5 times by mole, based on the diamine component.

Among the methods for synthesizing the above three polyamic acid esters, a polyamic acid ester having a high molecular weight can be obtained, and therefore, the synthesis method of the above (A) or (B) 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. The precipitated polyamic acid ester powder is obtained several times, washed with a poor solvent, and then dried at room temperature or heated 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. Methanol and ethanol are preferred.

&Lt; Liquid crystal alignment treatment agent &

The liquid crystal alignment treatment agent of the present invention contains a soluble polyimide represented by the above formula (1) and a polyamic acid ester represented by the formula (2). Typically, the liquid crystal alignment treatment agent of the present invention is in the form of a solution in which a soluble polyimide and a polyamic acid ester (hereinafter sometimes referred to as a polymer) are dissolved in an organic solvent. When the polyamic acid ester and / or polyamic acid are synthesized in an organic solvent as long as they have such a form of the solution, for example, they may be the reaction solution itself or may be obtained by diluting the reaction solution with an appropriate solvent do. When a polyamic acid ester and / or a polyamic acid is obtained as a powder, it may be dissolved in an organic solvent to form a solution.

The soluble polyimide has a weight average molecular weight of preferably from 5,000 to 200,000, more preferably from 10,000 to 100,000 in terms of solubility in an organic solvent. The number average molecular weight is preferably 5,000 to 100,000, more preferably 10,000 to 50,000.

On the other hand, the weight average molecular weight of the polyamic acid ester is preferably 5,000 to 200,000, more preferably 10,000 to 100,000. The number average molecular weight is preferably 5,000 to 100,000, more preferably 10,000 to 50,000.

The content of the polyimide and the content of the polyamic acid ester in the liquid crystal alignment treatment agent of the present invention are preferably in the range of 1/9 to 9/1 based on the polyamic acid ester / polyamic acid (mass ratio) Is 2/8 to 8/2, particularly preferably 3/7 to 7/3. By setting the ratio in this range, it is possible to provide a liquid crystal alignment treatment agent having both excellent liquid crystal alignability and electrical characteristics.

The content (concentration) of the polymer in the liquid crystal alignment treatment agent of the present invention can be appropriately changed depending on the thickness of the liquid crystal alignment film to be formed. However, from the viewpoint of forming a uniform and defect-free coating film, , The content of the polymer component is preferably 0.5% by mass or more, and is preferably 15% by mass or less, and more preferably 1 to 10% by mass, from the viewpoint of the storage stability of the solution.

In this case, it is also possible to prepare a solution in which the concentration of the polymer is rich in advance, and to dilute the concentrated solution when the liquid crystal alignment treatment agent is used. The concentration of the concentrated solution of such a polymer component is preferably 10 to 30 mass%, more preferably 10 to 15 mass%.

The polymer component powder may be dissolved in an organic solvent to prepare a solution. The heating temperature is preferably 20 to 150 占 폚, particularly preferably 20 to 80 占 폚.

The organic solvent contained in the liquid crystal alignment treatment 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. Among them, in view of solubility, N-methyl-pyrrolidone, N-ethyl-pyrrolidone and the like having a large polarity are preferable.

The organic solvent may be used alone or in combination of two or more. It may be mixed with an organic solvent which can not uniformly dissolve the polymer component, so long as the polymer is not precipitated.

The liquid crystal alignment treatment agent of the present invention may contain, in addition to the organic solvent for dissolving the polymer component, a solvent for improving the uniformity of the coating film when the liquid crystal alignment treatment 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. Of these, butyl cellosolve and ethyl carbitol are preferably used. These solvents may be used in combination of two or more.

In the liquid crystal alignment treatment agent of the present invention, the organic solvent for dissolving the polymer component may be used in combination with a solvent for improving the uniformity of the coating film. The amount of the organic solvent and the solvent used is preferably 30/70 To 90/10, preferably 60/40 to 80/20.

The liquid crystal alignment treatment agent of the present invention may contain various additives such as a silane coupling agent and a crosslinking agent. The silane coupling agent is added for the purpose of improving the adhesion between the substrate to which the liquid crystal alignment treatment agent is applied and the liquid crystal alignment film formed thereon. Specific examples of the silane coupling agent are given below, 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 ureide-based silane coupling agent such as 3-ureido propyl triethoxysilane; 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.

When the silane coupling agent is added, it is preferable to add the solvent for improving the uniformity of the coating film in order to prevent precipitation of the polymer. When a silane coupling agent is added, it may be added to both of the polyamic acid ester solution, the polyamic acid solution, or the polyamic acid ester solution and the polyamic acid solution before mixing the polyamic acid ester solution and the polyamic acid solution. Further, it can be added to a mixed solution of polyamic acid ester and polyamic acid.

Since the silane coupling agent is added for the purpose of improving the adhesion between the polymer and the substrate, the silane coupling agent may be added to the polyamic acid solution which can be localized in the film and at the substrate interface, and a polymer and a silane coupling agent It is more preferable to mix it with the polyamic acid ester solution after sufficiently reacting.

An imidization accelerator may be added in order to efficiently proceed the imidization of the polyamic acid ester when the coating film is baked after the liquid crystal alignment treatment agent of the present invention is applied to the substrate.

Specific examples of the imidization accelerator of the polyamic acid ester include, but are not limited to, the following.

(28)

[Chemical Formula 29]

In the formulas (B-1) to (B-17), D is independently a tert-butoxycarbonyl group or a 9-fluorenylmethoxycarbonyl group. In the formulas (B-14) to (B-17), there is a plurality of D's in one formula, but they may be the same or different.

The content of the imidization promoter is not particularly limited as long as the effect of promoting the thermal imidization of the polyamic acid ester can be obtained. However, the content of the imidization promoter in the amic acid ester moiety 1 of the formula (12) contained in the polyamic acid ester in the liquid crystal alignment- Is preferably at least 0.01 mol, more preferably at least 0.05 mol, and even more preferably at least 0.1 mol, relative to the molar amount. In addition, since the imidization promoter remaining in the film after firing itself has a minimal adverse effect on various characteristics of the liquid crystal alignment film, the amic ester moiety 1 of the formula (12) contained in the polyamic acid ester in the liquid crystal alignment treatment agent The imidization promoter is preferably 2 mol or less, more preferably 1 mol or less, and still more preferably 0.5 mol or less, based on the molar amount.

(30)

When an imidization accelerator is added, since imidization may proceed by heating, it is preferable to add it after diluting with a good solvent and a poor solvent.

&Lt; Liquid crystal alignment film &

The liquid crystal alignment film of the present invention is a film obtained by applying the liquid crystal alignment treatment agent to a substrate, drying it, and then firing it.

The substrate to which the liquid crystal alignment treatment agent of the present invention is applied is not particularly limited as long as it is a substrate having high transparency. A plastic substrate such as a glass substrate, a silicon nitride substrate, an acrylic substrate or a polycarbonate substrate can be used. It is preferable from the viewpoint of simplification of the process. In a reflection-type liquid crystal display element, an opaque material such as a silicon wafer can be used only for a substrate on one side, and a material for reflecting light such as aluminum can be used for the electrode in this case.

Examples of the application method of the liquid crystal alignment treatment agent of the present invention include a spin coating method, a printing method, and an ink jet method. The drying and firing steps after the application of the liquid crystal alignment treatment agent of the present invention can be carried out at arbitrary temperature and time. Usually, the organic solvent is dried at 50 to 120 ° C for 1 to 10 minutes, preferably at 60 to 100 ° C for 2 to 5 minutes, and then at 150 to 300 ° C for 5 to 120 Min, preferably 180 to 230 ° C for 10 to 60 minutes.

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.

As the method of orienting the obtained liquid crystal alignment film, there can be mentioned the rubbing method and the photo alignment treatment method, but the liquid crystal alignment treatment agent of the present invention is particularly useful when used in the rubbing 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 on which a liquid crystal alignment film is formed from the liquid crystal alignment treatment agent of the present invention by the above-mentioned technique and subjecting the alignment treatment to a liquid crystal cell by a known method .

The manufacturing method of the liquid crystal cell is not particularly limited. For example, a pair of substrates on which a liquid crystal alignment film is formed is laminated with the liquid crystal alignment film face inside, preferably 1 to 30 占 퐉, more preferably 2 to 10 占 퐉 A space is interposed therebetween, the periphery is fixed with a sealant, and liquid crystal is injected 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 further detail with reference to examples. It goes without saying that the present invention is not limited to these embodiments.

The abbreviations used in the examples and comparative examples and the measurement methods of the respective properties are as follows.

(Tetracarboxylic acid dianhydride)

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

PMDA: 2,5-bis (methoxycarbonyl) terephthalic acid

TDA: 3,4-Dicarboxy-1,2,3,4-tetrahydro-1-naphthalene succinic acid dianhydride

(Dicarboxylic acid diester)

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

PMDE: 2,5-bis (methoxycarbonyl) terephthalic acid

(Diamine)

Me-DADPA: N1- (4-aminophenyl) -N1-methylbenzene-1,4-diamine

DADPA: 4,4'-diaminodiphenylamine

p-PDA: p-phenylenediamine

DDM: 4,4'-diaminodiphenylmethane

B76: 2,4-diamino-N, N-diallylamine

3-ABA: 3- (aminomethyl) aniline

C16DAB: 4-hexadecyloxy-1,3-diaminobenzene

C18DAB: 4-octadecyloxy-1,3-diaminobenzene

(Condensation agent)

DMT-MM: 4- (4,6-dimethoxy-1,3,5-triazin-2-yl) -4-methylmorpholin-

(Organic solvent)

NMP: N-methyl-2-pyrrolidone

BC: butyl cellosolve

? -BL:? -butyrolactone

(Example 1)

CBDA (70) PMDA / B76 (30) 3ABA (50) APC16

(0.030 mol) of CBDA, 6.54 g (0.030 mol) of PMDA, 6.10 g (0.030 mol) of B76 as a diamine component and 6.11 g (0.050 mol) of 3-ABA as a tetracarboxylic acid dianhydride component. , And 6.96 g (0.020 mol) of C18DAB were reacted in 222.39 g of NMP at room temperature for 24 hours to obtain a polyamic acid solution (PAA-1).

30.00 g of NMP, 3.90 g of acetic anhydride and 1.81 g of pyridine were added to 20.00 g of the polyamic acid solution (PAA-1). The mixture was stirred at room temperature for 30 minutes and then reacted at 50 DEG C for 3 hours with stirring. After completion of the reaction, the mixture was slowly poured into 195 g of methanol to precipitate a polymer, which was then stirred for 30 minutes, and the solid was recovered by filtration. The obtained solid was sufficiently washed with methanol, and then vacuum-dried at 100 ° C to obtain a polyimide powder (SPI-1). The polyimide had a number average molecular weight of 13,600, a weight average molecular weight of 33,800, and an imidization rate of 90%.

To 6.47 g of the polyimide powder (SPI-1), 58.23 g of? -BL was added and dissolved by stirring at 50 占 폚 for 24 hours to confirm that it was completely dissolved. Thereafter, 15.28 g of γ-BL and 19.73 of BC were added, and the mixture was stirred at 50 ° C. for 24 minutes to obtain a polyimide solution (SPI) having polyimide of 6.0 mass%, γ-BL of 74 mass% and BC of 20 mass% -1). The obtained polyimide solution was a liquid crystal alignment treatment agent (AL-1). The rubbing resistance, whitening, and voltage holding ratio (VHR) were evaluated using this coating liquid.

The evaluation results of the rubbing resistance, whitening, and VHR obtained using the coating liquid of Example 1 are shown in Table 1 together with the composition ratio (weight ratio) of the polymer solution.

(Example 2)

TDA / p-PDA (90) APC18

Of 61.66 g of NMP using 7.51 g (0.025 mol) of TDA as a tetracarboxylic acid dianhydride component and 2.43 g (0.023 mol) of p-PDA as a diamine component and 0.94 g (0.0025 mol) of C18 DAB, And reacted at 50 DEG C for 24 hours to obtain a polyamic acid solution (PAA-2).

30.67 g of NMP, 7.18 g of acetic anhydride and 3.33 g of pyridine were added to 20.00 g of the polyamic acid solution (PAA-2). The mixture was stirred at room temperature for 30 minutes, and reacted at 40 占 폚 for 3 hours with stirring. After completion of the reaction, 214 g of methanol was slowly poured to precipitate the polymer, which was then stirred for 30 minutes, and the solid was recovered by filtration. The obtained solid was thoroughly washed with methanol and vacuum-dried at 100 ° C to obtain a polyimide powder (SPI-2). The polyimide had a number average molecular weight of 12,400, a weight average molecular weight of 27,400, and an imidization ratio of 86%.

29.90 g of? -BL was added to 2.60 g of the polyimide powder (SPI-2) and dissolved by stirring at 50 占 폚 for 24 hours to confirm that it was completely dissolved. Thereafter, 2.16 g of γ-BL and 8.67 g of BC were added and stirred at 50 ° C. for 24 minutes to obtain a polyimide solution having a polyimide content of 6.0% by mass, a γ-BL content of 94% by mass and a BC content of 20% SPI-2). The resulting polyimide solution was a liquid crystal alignment treatment agent (AL-2). Using this coating liquid, the same evaluation as in Example 1 was carried out.

(Example 3)

CBDE (50) PMDE / DDM

As the dicarboxylic acid diester component, 11.97 g (0.046 mol) of CBDE and 14.12 g (0.050 mol) of PMDE, 19.83 g (0.10 mol) of DDM as a diamine component, 5.10 g Mol) and 83.20 g (0.30 mol) of DMT-MM as a condensing agent were reacted in 719.18 g of NMP at room temperature for 3 hours to obtain a polyamic acid ester solution (PAE-1).

This polyamic acid ester solution was poured into 4692 g of methanol and the precipitated solid was recovered. This solid was washed several times with methanol, and then dried under reduced pressure at 100 ° C to obtain a white powder of polyamic acid ester (PAE-1). This polyamic acid ester had a number average molecular weight of 12,900 and a weight average molecular weight of 28,800.

To 2.15 g of the obtained polyamic acid ester (PAE-1), 15.77 g of NMP was added and the mixture was stirred at room temperature for 4 hours. At the end of stirring, the polyamic acid ester was completely dissolved. Then, 5.47 g of NMP and 9.20 g of BC were added to this solution and stirred at room temperature for 2 hours to prepare a solution containing 6 mass% of polyamic acid ester, 74 mass% of NMP and 20 mass% of BC. The polyamic acid ester solution thus prepared was used as a liquid crystal alignment treatment agent (AL-3). Using this coating liquid, the same evaluation as in Example 1 was carried out.

(Example 4)

CBDE / Me-DADPA (50) DADPA (30) DDM

(0.033 mol) of CBDE as a dicarboxylic acid diester component, 3.73 g (0.018 mol) of Me-DADPA as a diamine component, 2.10 g (0.011 mol) of DADPA, 1.39 g (0.0070 mol) of DDM, A polyamic acid ester solution (PAE-MM) was prepared by reacting 1.81 g (0.018 mol) of triethylamine as a base and 25.19 g (0.091 mol) of DMT-MM as a condensing agent in 247.11 g of NMP at room temperature for 4 hours. 2).

This polyamic acid ester solution was poured into 1594 g of methanol, and the precipitated solid was recovered. This solid was washed several times with methanol, and then dried under reduced pressure at 100 ° C to obtain a white powder of polyamic acid ester (PAE-2). The polyamic acid ester had a number average molecular weight of 12,300 and a weight average molecular weight of 33,500.

To 2.18 g of the obtained polyamic acid ester (PAE-2), 19.62 g of NMP was added and the mixture was stirred at room temperature for 5 hours. At the end of stirring, the polyamic acid ester was completely dissolved. Then, 1.01 g of? -BL and 6.54 g of BC were added to this solution and stirred at room temperature for 1 hour to obtain a polyamic acid ester of 6 mass%,? -BL of 57 mass%, NMP of 17 mass%, BC 20% by mass was prepared. The polyamic acid ester solution thus prepared was used as a liquid crystal alignment treatment agent (AL-4). Using this coating liquid, the same evaluation as in Example 1 was carried out.

(Example 5)

CBDA (50) PMDA / DDM

113.00 g of gamma -BL and 113.00 g of NMP (0.100 g) were dissolved in a mixture of 9.81 g (0.050 mol) of CBDA and 10.25 g (0.047 mol) of PMDA as a tetracarboxylic acid dianhydride component and 19.83 g And reacted at 113.00 g in a room temperature for 3 hours to obtain a polyamic acid solution (PAA-1).

198.97 g of polyamic acid solution (PAA-1) was diluted with 204.23 g of? -BL, 14.63 g of NMP and 73.74 g of BC to obtain a solution containing 6 mass% of solid matter (polyamic acid), 59 mass% of γ- By mass and 20% by mass and 15% by mass of BC, respectively. This polyamic acid had a number average molecular weight of 20,900 and a weight average molecular weight of 57,900.

(Example 6)

(Example 1) / (Example 3) = 3/7

The polyimide solution (SPI-1) prepared in Example 1 and the polyamic ester acid solution (PAE-1) prepared in Example 3 were mixed so as to have a weight ratio of 30:70, and the mixture was stirred at room temperature for 1 hour, To obtain a treating agent (AL-5). Using this coating liquid, the same evaluation as in Example 1 was carried out.

(Example 7)

(Example 2) / (Example 3) = 3/7

The polyimide solution (SPI-2) prepared in Example 1 and the polyamic ester acid solution (PAE-1) prepared in Example 3 were mixed in a weight ratio of 30:70 and stirred at room temperature for 1 hour to form a liquid crystal alignment To obtain a treating agent (AL-6). Using this coating liquid, the same evaluation as in Example 1 was carried out.

(Example 8)

(Example 1) / (Example 4) = 3/7

The polyimide solution (SPI-1) prepared in Example 1 and the polyamic ester acid solution (PAE-2) prepared in Example 4 were mixed in a weight ratio of 30:70 and stirred at room temperature for 1 hour to form liquid crystal alignment To obtain a treating agent (AL-7). Using this coating liquid, the same evaluation as in Example 1 was carried out.

(Example 9)

(Example 2) / (Example 4) = 3/7

The polyimide solution (SPI-2) prepared in Example 2 and the polyamic ester acid solution (PAE-2) prepared in Example 4 were mixed in a weight ratio of 30:70 and stirred at room temperature for 1 hour to form a liquid crystal alignment To obtain a treating agent (AL-8). Using this coating liquid, the same evaluation as in Example 1 was carried out.

(Comparative Example 1)

(Example 2) / (Example 5) = 3/7

The polyimide solution (SPI-2) prepared in Example 2 and the polyamic acid solution (PAA-1) prepared in Example 5 were mixed at a weight ratio of 30:70 and stirred at room temperature for 1 hour to prepare a liquid crystal alignment treatment agent (AL-9). Using this coating liquid, the same evaluation as in Example 1 was carried out.

&Lt; Measurement of molecular weight &

The molecular weight of the polyimide obtained by the polymerization reaction was measured by a GPC (room temperature gel permeation chromatography) apparatus and the number average molecular weight and the weight average molecular weight were calculated as polyethylene glycol and polyethylene oxide conversion values.

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

Column: Manufactured by Shodex Co. (serial of KD803 and KD805)

Column temperature: 50 ° C

Eluent: 30 mmol / l (liter) of lithium bromide-hydrate (LiBr 占 O 2O), 30 mmol / l of phosphoric anhydride crystal (o-phosphoric acid) as the additive, Furan (THF) of 10 ml / l)

Flow rate: 1.0 ml / min

Standard Samples for Calibration Curve: TSK standard polyethylene oxide (molecular weight about 900,000, 150,000, 100,000, and 30,000) manufactured by Toso Corporation, and polyethylene glycol (molecular weight about 12,000, 4,000, and 1,000) manufactured by Polymer Laboratories.

&Lt; Production of liquid crystal cell &

A liquid crystal cell was prepared as follows for the liquid crystal alignment treatment agents prepared in Examples 1 to 4 and 6 to 10.

The liquid crystal alignment treatment agent was spin-coated on a glass substrate on which a transparent electrode was formed, dried on a hot plate at 70 占 폚 for 70 seconds, and then baked on a hot plate at 210 占 폚 for 10 minutes to form a 100 nm thick coating film. The coated film surface was rubbed with a rubbing device having a roll diameter of 120 mm with a rayon cloth under the conditions of a roll revolution rate of 1000 rpm, a roll advancing speed of 50 mm / sec, and an indentation amount of 0.3 mm to obtain a substrate on which a liquid crystal alignment film was formed.

Next, two substrates on which liquid crystal alignment films were formed were prepared, spacers having a size of 6 mu m were dispersed on one liquid crystal alignment film surface, a sealant was printed thereon, and another liquid crystal alignment film , Followed by attaching so that the rubbing direction was straight. Then, the sealant was cured to prepare a hollow cell. A liquid crystal MLC-2003 (manufactured by Merck Japan Co.) was injected into this bin cell by a vacuum injection method and the injection port was sealed to obtain a twisted nematic liquid crystal cell.

Methods of measuring the physical properties of each liquid crystal cell and evaluating the characteristics are described below.

The compositions of the liquid crystal alignment treatment agents in Examples 2 to 4, Examples 6 to 9, and Comparative Example 1, measurement results of the physical properties of each liquid crystal alignment film, and evaluation of properties were summarized in Table 1 Respectively.

&Lt; Measurement of voltage holding ratio (VHR) &gt;

The voltage holding ratio of the manufactured twisted nematic liquid crystal cell was measured by applying a voltage of 4 V to 60 ㎍ at a temperature of 90 캜 and measuring the voltage after 166.7 ms to determine the degree of voltage retention Respectively.

For the measurement of the voltage holding ratio, a voltage sustaining ratio measuring device (VHR-1) manufactured by Toyotec Corporation was used.

<Estimation of Accumulated Charge (RDC)>

A DC voltage was applied to the manufactured twisted nematic liquid crystal cell at a temperature of 23 ° C at intervals of 0 V to 0.1 V at intervals of 1.0 V to measure the flicker amplitude level at each voltage to prepare a calibration curve. After grounding (grounding) for 5 minutes, an AC voltage of 3.0 V and a DC voltage of 5.0 V were applied, and the flicker amplitude level after 1 hour was measured, and the RDC was estimated by comparing with the previously prepared calibration curve Is referred to as the flicker reference method).

Here, RDC (after OFF) represents a value immediately after the AC voltage 3.0 V and the DC voltage 5.0 V are applied for 1 hour, and RDC (after 5 minutes) represents the value immediately after OFF and after 30 minutes of accumulation Represents the value of charge.

Industrial availability

According to the liquid crystal alignment treatment agent of the present invention, even when the imidization ratio of the soluble polyimide is high, a whitening phenomenon does not occur at the time of forming a coating film, so that a liquid crystal alignment film having good printability and good rubbing resistance of the coating film is obtained , The voltage holding ratio (VHR) and the stored electric charge (RDC) of the obtained liquid crystal alignment film are excellent and the liquid crystal display device having the liquid crystal alignment film can be used as a TN device, an STN device, a TFT liquid crystal device, Type liquid crystal display device.

The entire contents of the specification, claims, and abstract of Japanese Patent Application No. 2012-082729 filed on March 30, 2012 are hereby incorporated herein by reference as the disclosure of the specification of the present invention.

Claims (15)

A liquid crystal alignment treatment agent characterized by containing a soluble polyimide represented by the following formula (1) and a polyamic acid ester represented by the following formula (2).
[Chemical Formula 1]

In the formula (2), X ₂ is a tetravalent organic group, Y ₂ is a divalent organic group, R ₁ is a tetravalent organic group, and Y ₁ is a divalent organic group. ₁ is an alkyl group having 1 to 5 carbon atoms, A ₁ and A ₂ are each independently a hydrogen atom or an alkyl group, alkenyl group or alkynyl group having 1 to 10 carbon atoms which may have a substituent. The method according to claim 1,
A liquid crystal alignment treatment agent wherein R ₁ in the formula (2) is a methyl group. 3. The method according to claim 1 or 2,
Wherein at least one of X ₁ and X ₂ in the formulas (1) and (2) is independently selected from the following formulas:
(2)

4. The method according to any one of claims 1 to 3,
A liquid crystal alignment treatment agent having the following structure in which X ₂ has an aromatic ring in formula (2).
(3)

4. The method according to any one of claims 1 to 3,
In the liquid crystal alignment treatment agent of the formula (1), X ₁ has an aliphatic structure or an alicyclic structure. 6. The method according to any one of claims 1 to 5,
Wherein the polyamic acid ester has a weight average molecular weight of 5,000 to 200,000. 7. The method according to any one of claims 1 to 6,
Wherein the soluble polyimide has an imidization ratio of 50% or more and a weight average molecular weight of 5,000 to 200,000. 8. The method according to any one of claims 1 to 7,
Wherein the ratio of the content of the soluble polyimide to the content of the polyamic acid ester (content of the soluble polyimide / content of the polyamic acid ester) in the mass ratio is 1/9 to 9/1. 9. The method according to any one of claims 1 to 8,
Wherein the soluble polyimide and the organic solvent for dissolving the polyamic acid ester are contained, and the content of the soluble polyimide and the total amount of the polyamic acid ester is 0.5 to 15 mass%. 10. The method of claim 9,
Wherein the organic solvent contains at least one member selected from the group consisting of N-methyl-pyrrolidone, N-ethyl-pyrrolidone, and? -Butyrolactone. 11. The method according to any one of claims 1 to 10,
Further, a liquid crystal alignment treatment agent containing a solvent. 12. The method of claim 11,
Wherein the solvent is butyl cellosolve. A liquid crystal alignment film obtained by applying the liquid crystal alignment treatment agent according to any one of claims 1 to 12 and firing. 14. The method of claim 13,
Wherein the thickness of the coating film obtained by applying and firing the liquid crystal alignment treatment agent is 5 to 300 nm. A liquid crystal display element comprising the liquid crystal alignment film according to claim 13 or 14.