TW201538569A - Liquid crystal aligning agent, and liquid crystal display element using same - Google Patents

Abstract

A liquid crystal alignment agent containing an imidized polymer obtained by ring-closing a polyimide precursor having repeating units represented by formula (1), at least a part of the Y in formula (1) having the structure represented by the following formula (2). In formula (1), Y is a divalent organic group derived from a diamine component, X is a tetravalent organic group derived from a tetracarboxylic acid derivative, A1 and A2 are, independently, a hydrogen atom or a C1-10 alkyl group which may have a substituent group, a C2-10 alkenyl group which may have a substituent group, or a C2-10 alkynyl group which may have a substituent group, and R1 is a hydrogen atom or a C1-10 alkyl group.

Description

Liquid crystal alignment agent and liquid crystal display element using same

The present invention relates to a liquid crystal alignment agent used for the production of a liquid crystal display element, a liquid crystal alignment film obtained from the liquid crystal alignment agent, and a liquid crystal display element using the liquid crystal alignment film.

Liquid crystal display elements are known as display devices that are lightweight, thin, and low in power consumption. In recent years, a high-definition liquid crystal display element used for a mobile phone or a tablet type end which is rapidly expanding development has reached a remarkable development requiring improvement of the display quality.

The liquid crystal display element is configured by sandwiching a liquid crystal layer on a transparent substrate by providing one of the electrodes. On the other hand, in the liquid crystal display device, an organic film made of an organic material in a state in which the liquid crystal is desired to be aligned between the substrates is used as a liquid crystal alignment film. In other words, the liquid crystal alignment film is a constituent member of the liquid crystal display element, and is formed on the surface of the liquid crystal that is bonded to the substrate on which the liquid crystal is sandwiched, and serves as a direction in which the liquid crystal alignment is oriented in a predetermined direction. And by the liquid crystal alignment film, the pretilt angle of the liquid crystal can be controlled. A method of increasing the pretilt angle mainly by selecting a structure of polyimine (see Patent Document 1), a method of reducing the pretilt angle (see Patent Document 2), and the like are known.

[Previous Technical Literature] [Patent Document]

[Patent Document 1] Japanese Patent Publication No. 09-278724

[Patent Document 2] Japanese Patent Publication No. Hei 10-123532

[Summary of the Invention]

In recent years, liquid crystal display elements have been used for mobile applications such as smart phones or general mobile phones. In such applications, in order to secure a large number of display surfaces as much as possible, it is necessary to make the width of the sealant used between the substrates to which the liquid crystal display elements are adhered to be narrower than in the past. For the above reasons, it is also required to bond the position of the sealant to the end of the liquid crystal alignment film having weak adhesion to the sealant or to the upper portion of the liquid crystal alignment film. In this case, particularly when used under high temperature and high humidity conditions, water is easily mixed between the self-sealant and the liquid crystal alignment film, and display unevenness occurs in the vicinity of the frame of the liquid crystal display element.

Therefore, the present invention has an object of providing a liquid crystal alignment agent which can improve the adhesion between a sealant and a liquid crystal alignment film and can suppress the occurrence of display unevenness in the vicinity of the frame of the liquid crystal display element under high temperature and high humidity conditions.

The inventors of the present invention have completed the present invention in order to solve the above problems and carry out detailed review results. That is, the gist of the present invention is as follows.

A liquid crystal aligning agent comprising a polyimine precursor obtained by selecting a reactive diamine component and a tetracarboxylic acid derivative, and a ruthenium imidization polymerization of the polyimine precursor by hydrazine imidization At least one of the substances is characterized in that the polyimine precursor has a repeating unit represented by the following formula (1).

In the formula (1), Y is a divalent organic group derived from a diamine component, X is a tetravalent organic group derived from a tetracarboxylic acid derivative, and each of A ¹ and A ^{2 is} independently a hydrogen atom or a carbon which may have a substituent An alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms which may have a substituent, an alkynyl group having 2 to 10 carbon atoms which may have a substituent, and R ¹ being a hydrogen atom or an alkyl group having 1 to 10 carbon atoms. At least a part of Y is a structure of the following formula (2).

2. The liquid crystal alignment agent according to the above 1, wherein the above formula (1) In the repeating unit shown, at least a part of X is a tetravalent organic group having an alicyclic structure or an aliphatic structure.

3. The liquid crystal alignment agent according to the above 2, wherein, in the repeating unit represented by the above formula (1), at least a part of X is selected from the following (X-9), (X-26), (X-27). Structure.

4. The liquid crystal alignment agent according to the above 2, wherein, in the repeating unit represented by the formula (1), the ratio of X to a tetravalent organic group having an alicyclic structure or an aliphatic structure is 10 to 100 mol%.

5. The liquid crystal alignment agent according to the above 3, wherein in the repeating unit represented by the above formula (1), the ratio of X in any one of (X-9), (X-26), and (X-27) is 10~100% by mole.

In the liquid crystal alignment agent according to any one of the above-mentioned formulas (1), the ratio of the structure of Y in the above formula (2) is 10 to 100 mol%.

7. A liquid crystal alignment film which is obtained by applying the liquid crystal alignment agent according to any one of the above 1 to 6 to a substrate and firing it.

A liquid crystal display device comprising the liquid crystal alignment film according to the above 7th aspect.

By using the liquid crystal alignment agent of the present invention, it is possible to obtain a liquid crystal alignment film which improves the adhesion between the sealing agent and the liquid crystal alignment film and suppresses the occurrence of display unevenness in the vicinity of the frame of the liquid crystal display element under high temperature and high humidity conditions. Therefore, the liquid crystal display element having the liquid crystal alignment film can improve the adhesion between the sealant and the liquid crystal alignment film, thereby solving the display unevenness in the vicinity of the bezel, and is applicable to a large-screen and high-definition liquid crystal display.

[Formation of the Invention] <Liquid alignment agent>

The liquid crystal alignment agent of the present invention is a polyimine precursor obtained by selecting a reaction of a diamine component and a tetracarboxylic acid derivative, and a ruthenium imidized polymer obtained by imidating the polyimide precursor. At least one of the present invention is characterized in that the polyimine precursor has a repeating unit represented by the following formula (1).

In the formula (1), Y is a divalent organic group derived from a diamine component, X is a tetravalent organic group derived from a tetracarboxylic acid derivative, and each of A ¹ and A ^{2 is} independently a hydrogen atom or a carbon which may have a substituent An alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms which may have a substituent, an alkynyl group having 2 to 10 carbon atoms which may have a substituent, and R ¹ being a hydrogen atom or an alkyl group having 1 to 10 carbon atoms. At least a part of Y is a structure of the following formula (2).

The tetracarboxylic acid derivative to be used in the present invention may, for example, be a tetracarboxylic dianhydride, a tetracarboxylic acid monohydride, a tetracarboxylic acid, a dicarboxylic acid dialkyl ester or a dicarboxylic acid chloride dialkyl ester, but only It is not particularly limited as long as it can be reacted with a diamine.

In the formula (1), X is a tetravalent organic group derived from a tetracarboxylic acid derivative, and the structure is not particularly limited. Specific examples of X include X-1 to X-44 shown below.

In the formula (X-1), R ² to R ⁵ each independently represent a hydrogen atom, a methyl group or a phenyl group.

In the formula (1), X may be one type or a mixture of two or more types, and when X has an alicyclic structure or an aliphatic structure, adhesion can be made. Further, it is preferable to contain more than one type of X having an alicyclic structure or an aliphatic structure. A preferred ratio of X having an alicyclic structure or an aliphatic structure is 10 mol% or more of all X, preferably 50 mol% or more, more preferably 80 mol% or more.

As the structure of X having an alicyclic structure or an aliphatic structure, (X-1) to (X-16), (X-23) to (X-27), (X-41) to (X-43) It is preferable that (X-9), (X-26), and (X-27) are particularly excellent in strength.

In the formula (1), specific examples of the alkyl group in R ¹ include a methyl group, an ethyl group, a propyl group, an i-propyl group, an n-butyl group, an i-butyl group, and an s-butyl group. T-butyl, n-pentyl and the like.

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

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, a bicyclohexyl group and the like. The alkenyl group may be one in which one or more CH-CH structures present in the above-mentioned alkyl group are substituted by a C=C structure, and more specifically, a vinyl group, an aryl group, a 1-propenyl group, and a different one may be mentioned. Propylene group, 2-butenyl group, 1,3-butadienyl group, 2-pentenyl group, 2-hexenyl group, cyclopropenyl group, cyclopentenyl group, cyclohexenyl group and the like. Examples of the alkynyl group include those in which one or more CH ₂ -CH ₂ structures present in the alkyl group are substituted by a C≡C structure, and more specifically, an ethynyl group, a 1-propynyl group, and a 2-propane group. Alkynyl and the like.

The above alkyl, alkenyl or alkynyl group may have a substituent One step can form a ring structure by a substituent. Further, when a ring structure is formed by a substituent, it means that the substituents or a part of the substituent and the parent skeleton are bonded to each other 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 organic oxy group, an organic thio group, an organic fluorenyl group, a fluorenyl group, an ester group, a thioester group, and a phosphate group. , amidino, alkyl, alkenyl, alkynyl.

The halogen group as a substituent may, for example, be a fluorine atom, a chlorine atom, a bromine atom or an iodine atom.

The aryl group as a substituent may, for example, be a phenyl group. The aryl group may be further substituted by the other substituents described above.

The organooxy group as a substituent can be represented by a structure represented by O-R. The R may be the same or different and may be exemplified by the aforementioned alkyl group, alkenyl group, alkynyl group, aryl group and the like. These R may be further substituted by the aforementioned substituents. Specific examples of the organic oxy group include a methoxy group, an ethoxy group, a propyloxy group, a butoxy group, a pentyloxy group, a hexyloxy group, a heptyloxy group, and an octyloxy group.

The organothio group as a substituent may, for example, be a structure represented by -S-R. The R, the alkenyl group, the alkynyl group, the aryl group and the like can be exemplified as the R. These R may be further substituted by the aforementioned substituents. Specific examples of the organic sulfur group include a methylthio group, an ethylthio group, a propylthio group, a butylthio group, a pentylthio group, a hexylthio group, a heptylthio group, an octylthio group, and the like. .

The organic fluorenyl group as a substituent can be represented by a structure represented by -Si-(R) ₃ . The R may be the same or different and may be exemplified by the aforementioned alkyl group, alkenyl group, alkynyl group, aryl group and the like. These R may be further substituted by the aforementioned substituents. Specific examples of the organic fluorenyl group include a trimethyl fluorenyl group, a triethyl decyl group, a tripropyl decyl group, a tributyl fluorenyl group, a tripentyl fluorenyl group, a trihexyl fluorenyl group, and a pentyl dimethyl group. Base group, hexyl dimethyl fluorenyl group, and the like.

The fluorenyl group as a substituent can be represented by a structure represented by -C(O)-R. The R, the alkyl group, the alkenyl group, the aryl group and the like can be exemplified as the R. These R may be further substituted by the aforementioned substituents. Specific examples of the mercapto group include a methyl group, an ethenyl group, a propyl group, a butyl group, an isobutyl group, a vanillyl group, an isovanidyl group, a benzamidine group, and the like.

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

The thioester group as a substituent may be represented by a structure represented by -C(S)O-R or -OC(S)-R. The R, the alkenyl group, the alkynyl group, the aryl group and the like can be exemplified as the R. These R may be further substituted by the aforementioned substituents.

The phosphate group as a substituent can be represented by a structure represented by -OP(O)-(OR) ₂ . The R may be the same or different and may be exemplified by the aforementioned alkyl group, alkenyl group, alkynyl group, aryl group and the like. These R may be further substituted by the aforementioned substituents.

The amidino group as a substituent may be represented by -C(O)NH ₂ or -C(O)NHR, -NHC(O)R, -C(O)N(R) ₂ , -NRC(O) The structure shown by R. The R may be the same or different and may be exemplified by the aforementioned alkyl group, alkenyl group, alkynyl group, aryl group and the like. These R may be further substituted by the aforementioned substituents.

The aryl group as a substituent may be the same as the above aryl group. The aryl group may be further substituted by the other substituents described above.

The alkyl group as a substituent may be the same as the above-mentioned alkyl group. The alkyl group may be further substituted by the other substituents described above.

The alkenyl group as a substituent may be the same as the above alkenyl group. The alkenyl group may be further substituted by the other substituents described above.

The alkynyl group as a substituent may be the same as the alkynyl group described above. The alkynyl group can be further substituted by the other substituents described above.

In general, when a high-volume structure is introduced, the reactivity of the amine group or the liquid crystal alignment property may be lowered. As A ¹ and A ² , a hydrogen atom or an alkyl group having 1 to 5 carbon atoms which may have a substituent may be used. The base is preferably a hydrogen atom, a methyl group or an ethyl group.

In the formula (1), at least a part of Y is a structure of the formula (2). When the ratio of the structure of Y to the formula (2) is exemplified, it is 10 mol% to 100 mol%. Further, when the structure of the formula (2) is 50% or more of Y, it is preferable because the adhesion can be further improved, more preferably 70 mol% or more, and particularly preferably 90 mol% or more.

As described above, Y is not limited to the formula (2), and may contain other structures. Specific examples of the structure of other Ys include the following Y-1 to Y-115.

(In the formula (Y-102), m and n are each an integer of 1 to 11, m+n is an integer of 2 to 12, and in the formula (Y-107), h is an integer of 1 to 3, and the formula (Y- 104) and (Y-111), j is an integer from 0 to 3.)

Among them, Y-7, Y-21, Y-22, Y-23, Y-25, Y-26, Y-27, Y-43, Y-44, Y-45, Y-46, Y- 48. Y-56, Y-64, Y-66, Y-67, Y-68, Y-91, Y-92, Y-93 and other high linear structures can improve the alignment of liquid crystals as liquid crystal alignment films. Sex. Also, such as Y-69, Y-70, Y-71, Y-72, Y-73, Y-74, Y-75, Y-76, Y-77, Y-78, Y-79, Y-80, Y-81, Y-82, Y-83, Y-84, Y-85, Y-86, Y-87, Y- 88. Y-89 and Y-90 are equivalent to a side chain combination long-chain alkyl group, an aromatic ring, an aliphatic ring, a steroid skeleton, or the like, and can improve the pretilt angle of the liquid crystal when used as a liquid crystal alignment film. Further, when the structure of Y-111 can be used as a liquid crystal alignment film, good friction resistance can be obtained.

The polyimine precursor used in the present invention is obtained by reacting a diamine component with a tetracarboxylic acid derivative, and examples thereof include polyglycine or polydecylamine.

<Method for producing polylysine>

The polyaminic acid used in the polyimine precursor of the present invention can be synthesized by the method shown below.

Specifically, the tetracarboxylic acid dianhydride and the diamine may be used in the presence of an organic solvent at -20 ° C to 150 ° C, preferably at 0 ° C to 50 ° C for 30 minutes to 24 hours, preferably. It is synthesized for 1 to 12 hours of reaction.

The organic solvent used in the above reaction is preferably N,N-dimethylformamide, N-methyl-2-pyrrolidone or γ-butyrolactone from the viewpoint of solubility of the monomer and the polymer. One type may be used or two or more types may be used in combination. The concentration of the polymer is preferably from 1 to 30% by mass, and preferably from 5 to 20% by mass, from the viewpoint that the precipitation of the polymer is not easily caused and the high molecular weight body can be easily obtained.

The polylysine thus obtained can be dissolved by careful stirring The liquid is injected into a weak solvent to precipitate a polymer and recover. Further, the precipitation is carried out several times, and after washing with a weak solvent, the purified polyamic acid powder can be obtained by drying at room temperature or by heating. The weak solvent is not particularly limited, and examples thereof include water, methanol, ethanol, hexane, butyl cellosolve, acetone, and toluene.

<Method for producing polyamidomate>

The polyamidate used in the polyimine precursor of the present invention can be synthesized by the methods (1) to (3) shown below.

(1) When synthesizing from polyamic acid

Polyammonium esters can be synthesized by esterification of polyamic acid obtained from tetracarboxylic acid dianhydride and diamine.

Specifically, the polyamic acid and the esterifying agent can be carried out 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 for further It is synthesized by reaction in 1 to 4 hours.

As the esterifying agent, it is preferred to be easily removed by purification, and examples thereof include N,N-dimethylformamide dimethyl acetal and N,N-dimethylformamide diethyl condensate. Aldehyde, N,N-dimethylformamide dipropyl acetal, N,N-dimethylformamide dineopentyl butyl acetal, N,N-dimethylformamide di-t - butyl acetal, 1-methyl-3-p-tolyltriazene, 1-ethyl-3-p-tolyltriazene, 1-propyl-3-p-tolyltriazene 4-(4,6-Dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride or the like. The amount of esterification agent added is 2 to 6 moles for the repeat unit of poly-proline. The equivalent is good.

The solvent used in the above reaction is preferably N,N-dimethylformamide, N-methyl-2-pyrrolidone or γ-butyrolactone from the viewpoint of solubility of the polymer, and these can be used. One type or a mixture of two or more types is used. The concentration at the time of the synthesis is preferably from 1 to 30% by mass, and preferably from 5 to 20% by mass, from the viewpoint of not easily causing precipitation of the polymer and easily obtaining a high molecular weight body.

(2) When synthesizing by reaction of tetracarboxylic acid diester dichloride with diamine

Polyammonium esters can be synthesized from tetracarboxylic acid diester dichlorides and diamines.

Specifically, the tetracarboxylic acid diester dichloride and the diamine can be 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, it is synthesized by performing a reaction for 1 to 4 hours.

As the base, pyridine, triethylamine, 4-dimethylaminopyridine or the like can be used, but it is preferred to carry out the reaction with pyridine. The amount of the base to be added is preferably from 2 to 4 moles per mole of the tetracarboxylic acid diester dichloride from the viewpoint of easy removal amount and easy availability of a high molecular weight body.

The solvent to be used in the above-mentioned reaction is preferably N-methyl-2-pyrrolidone or γ-butyrolactone in view of the solubility of the monomer and the polymer. These may be used alone or in combination of two or more. The concentration of the polymer at the time of the synthesis is preferably from 1 to 30% by mass, and preferably from 5 to 20% by mass, from the viewpoint of not easily causing precipitation of the polymer and easily obtaining a high molecular weight body. also, In order to prevent hydrolysis of the tetracarboxylic acid diester dichloride, it is preferred to dehydrate the synthetic solvent used for the polyphthalate as much as possible, and it is preferable to prevent the incorporation of outside air in a nitrogen atmosphere.

(3) When synthesizing poly-proline from dicarboxylic acid diester and diamine

Polyammonium esters can be synthesized by polycondensation of a dicarboxylic acid diester with a diamine.

Specifically, the dicarboxylic acid diester and the diamine can be carried out in the presence of a condensing agent, a base or an organic solvent at 0 ° C to 150 ° C, preferably 0 ° C to 100 ° C, for 30 minutes to 24 hours. It is preferably synthesized by performing a reaction for 3 to 15 hours.

The condensing agent may be triphenyl phosphite, dicyclohexylcarbodiimide, 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride, N, N. '-Carbonyldiimidazole, dimethoxy-1,3,5-triazinylmethylmorpholinium, O-(benzotriazol-1-yl)-N,N,N',N'-four Methylurea tetrafluoroborate, O-(benzotriazol-1-yl)-N,N,N',N'-tetramethyluronium hexafluorophosphate, diphenyl (2,3-di Hydrogen-2-thioxo-3-benzoxazolyl)phosphonate and the like. The amount of the condensing agent added is preferably 2 to 3 moles per mole of the dicarboxylic acid diester.

As the base, a tertiary amine such as pyridine or triethylamine can be used. The amount of the base to be added is preferably 2 to 4 times the molar amount of the diamine component from the viewpoint of easy removal and easy availability of a high molecular weight body.

Further, with respect to the above reaction, the reaction can be carried out efficiently by adding Lewis acid as an additive. As a Lewis acid, to chlorinate Lithium halide such as lithium or lithium bromide is preferred. The amount of the Lewis acid added is preferably 0 to 1.0 times the molar amount of the diamine component.

Among the above-mentioned methods for synthesizing the three polyglycolates, the above-mentioned (1) or the above (2) synthesis method in which a high molecular weight polyglycolate is obtained is particularly preferable.

The solution of the polyglycolate obtained as described above can be precipitated by injecting it into a weak solvent with careful stirring. After several times of precipitation and washing with a weak solvent, the purified polyphthalate powder can be obtained by heating at room temperature or by heating. The weak solvent is not particularly limited, and examples thereof include water, methanol, isopropyl alcohol, ethanol, hexane, butyl cellosolve, acetone, toluene, and the like.

<Method for producing ruthenium iodide polymer>

The quinone imidized polymer used in the present invention can be produced by imidating the aforementioned polyimine precursor with ruthenium. When the ruthenium iodide polymer is produced from a polyimide precursor, the chemical ruthenium imidization of the base catalyst in the polyamidene precursor solution is the easiest. The chemical hydrazine imidization is carried out at a relatively low temperature for the ruthenium imidization reaction, which is preferred because it does not easily cause a decrease in the molecular weight of the polymer during the ruthenium imidization.

The chemical ruthenium imidization can be carried out by stirring a polyimine precursor to be imidized in an organic solvent in the presence of a basic catalyst. As the organic solvent, the solvent used in the above polymerization reaction can be used. Examples of the basic catalyst include pyridine, triethylamine, trimethylamine, tributylamine, and trioctylamine. Among them, triethylamine or pyridine is preferred because it has moderate alkalinity in the reaction. Moreover, as an acid anhydride, mention is made Among them, acetic anhydride, trimellitic anhydride, pyromellitic anhydride, and the like, in which acetic acid anhydride is used, can be easily purified after completion of the reaction.

The temperature at which the hydrazine imidization reaction is carried out is -20 ° C to 140 ° C, preferably 0 ° C to 100 ° C, and the reaction time of 1 to 100 hours can be carried out. The amount of the basic catalyst is 0.5 to 30 moles, preferably 2 to 20 moles, of the polyimide precursor. The oxime imidization ratio of the obtained polymer can be controlled by adjusting the amount of the catalyst, the temperature, and the reaction time. Since the solution after the imidization reaction remains as a catalyst or the like remaining, the obtained ruthenium iodide polymer is recovered by the method described below, and then dissolved in an organic solvent to obtain the liquid crystal alignment of the present invention. The agent is better.

The solution of the ruthenium iodide polymer obtained as described above is injected into a weak solvent with careful stirring, so that the polymer can be precipitated. After several times of precipitation and washing with a weak solvent, the purified quinone imidized polymer powder can be obtained by heating at room temperature or by heating.

The weak solvent is not particularly limited, and examples thereof include methanol, acetone, hexane, butyl cellosolve, heptane, methyl ethyl ketone, methyl isobutyl ketone, ethanol, toluene, and benzene.

<Liquid alignment agent>

<Liquid alignment agent>

The liquid crystal alignment agent used in the present invention is in the form of a solution having the aforementioned polyimine precursor or a quinone imidized polymer (hereinafter referred to as a polymer having a specific structure) dissolved in an organic solvent. The molecular weight of the polymer of a specific structure is preferably 2,000 to 500,000 by weight average molecular weight, preferably 5,000~ 300,000, more preferably 8,000 to 100,000. Further, the number average molecular weight is preferably from 1,000 to 250,000, preferably from 2,500 to 150,000, more preferably from 4,000 to 50,000.

The concentration of the polymer used in the liquid crystal alignment agent of the present invention can be appropriately changed by setting the thickness of the coating film to be formed, but it is 1% by weight or more from the viewpoint of forming a uniform and non-defective coating film. Preferably, it is preferably 10% by weight or less from the viewpoint of storage stability of the solution.

The organic solvent contained in the liquid crystal alignment agent to be used in the present invention is not particularly limited as long as the polymer having a specific structure can be uniformly dissolved. Specific examples thereof include N,N-dimethylformamide, N,N-diethylformamide, N,N-dimethylacetamide, and N-methyl-2. - pyrrolidone, N-ethyl-2-pyrrolidone, N-methyl caprolactam, 2-pyrrolidone, N-vinyl-2-pyrrolidone, dimethyl hydrazine, dimethyl Base, γ-butyrolactone, 1,3-dimethyl-imidazolidinone, 3-methoxy-N,N-dimethylpropane decylamine, and the like. These can be used alone or in combination of two or more. Moreover, even if it is a solvent which cannot melt|dissolve a polymer uniformly separately, it can mix with the said organic solvent in the range which does not isolate a polymer.

The liquid crystal alignment agent used in the present invention may contain a solvent which can improve the uniformity of the coating film when the liquid crystal alignment agent is applied to the substrate, in addition to the organic solvent in which the polymer having a specific structure is to be dissolved. The solvent is a solvent which uses a lower surface tension than the above organic solvent. Specific examples of the compound include ethyl cellosolve, butyl cellosolve, ethyl carbitol, butyl carbitol, ethyl carbitol acetate, ethylene glycol, and 1-methoxyl. Glycol-2-propanol, 1-ethoxy-2-propanol, 1-butoxy-2-propanol, 1-phenoxy-2-propanol, propylene glycol monoacetate, propylene glycol diacetate, propylene glycol-1-single Methyl ether-2-acetate, propylene glycol-1-monoethyl ether-2-acetate, butyl cellosolve acetate, dipropylene glycol, 2-(2-ethoxypropoxy)propanol, Methyl lactate, ethyl lactate, n-propyl lactate, n-butyl lactate, isoamyl lactate, and the like. These solvents may be used in combination of two or more types.

In the liquid crystal alignment agent of the present invention, a polymer other than the polymer described in the present invention may be added, and the dielectric constant or conductivity of the liquid crystal alignment film may be changed, in addition to the above, insofar as the effects of the present invention are not impaired. a cross-linking compound for the purpose of improving the adhesion of the liquid crystal alignment film to the substrate, and a cross-linking compound for the purpose of improving the adhesion of the liquid crystal alignment film to the substrate, or a conductive material; Further, in the case of firing a coating film, the ruthenium imidization accelerator can be more efficiently carried out by heating the polyimide precursor by heating.

<Liquid alignment film>

The liquid crystal alignment film of the present invention is a film obtained by applying the liquid crystal alignment agent onto a substrate, drying and baking. The substrate to which the liquid crystal alignment agent of the present invention is applied is not particularly limited as long as it has high transparency, and a plastic substrate such as a glass substrate, a tantalum nitride substrate, an acrylic substrate or a polycarbonate substrate can be used. When a substrate such as an electrode for liquid crystal driving is to be used, it is preferable from the viewpoint of simplifying the process. Further, in the reflective liquid crystal display device, an opaque substance such as a germanium wafer may be used as the one-side substrate, and a material such as aluminum which can reflect light may be used as the electrode.

The coating method of the liquid crystal alignment agent of the present invention may, for example, be a spin coating method, a printing method, an inkjet method or the like. The drying and baking steps after the application of the liquid crystal alignment agent of the present invention can be carried out at any temperature and time. Generally, in order to sufficiently remove the organic solvent contained, it is dried at 50 ° C to 120 ° C for 1 minute to 10 minutes, and then baked at 150 ° C to 300 ° C for 5 minutes to 120 minutes. The thickness of the coating film after firing is not particularly limited. When it is too thin, the reliability of the liquid crystal display element may be lowered. Therefore, it is preferably 5 to 300 nm and preferably 10 to 200 nm.

As a method of performing the alignment treatment of the obtained liquid crystal alignment film, a rubbing method, a photoalignment processing method, and the like can be given.

Specific examples of the photo-alignment treatment method include a method of irradiating a polarized radiation in a predetermined direction on the surface of the coating film, and optionally performing heat treatment at a temperature of 150 to 250 ° C to impart a liquid crystal alignment energy. As the radiation, ultraviolet rays and visible rays having a wavelength of 100 nm to 800 nm can be used.

[Liquid Crystal Display Element]

The liquid crystal display device of the present invention obtains a substrate having a liquid crystal alignment film from the liquid crystal alignment agent of the present invention by the above-described method, and performs alignment treatment by rubbing treatment or the like, and then forms a liquid crystal display element by a known method.

The method for producing the liquid crystal cell of the liquid crystal display device is not particularly limited. For example, a pair of substrates on which a liquid crystal alignment film is formed may be used, and the liquid crystal alignment film surface is inside, and it is preferably 1 to be sandwiched. 30μm, more preferably 2~10μm spacer, surrounded by a sealant The method of injecting liquid crystal and sealing is general. The method of encapsulating the liquid crystal is not particularly limited, and a vacuum method in which the produced liquid crystal is decompressed and then injected into a liquid crystal, a dropping method in which liquid crystal is dropped, and sealing is exemplified. Since the liquid crystal alignment film obtained by the liquid crystal alignment agent of the present invention has excellent characteristics, it can be used as a liquid crystal display element such as VA, TN, STN, TFT, or a lateral electric boundary type, and further as a ferroelectric and anti-strong dielectric liquid crystal. The liquid crystal alignment film for display elements is used.

[Examples]

The invention is illustrated in more detail below by the examples, but the invention is not limited thereto.

The abbreviations of the compounds used in the examples and comparative examples and the methods for evaluating the characteristics are as follows.

NMP: N-methyl-2-pyrrolidone

BCS: butyl cellosolve

CA-1: pyromellitic dianhydride

CA-2: 3,3',4,4'-biphenyltetracarboxylic dianhydride

CA-3: 1,2,3,4-cyclobutane tetracarboxylic dianhydride

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

CA-5: 1,2,3,4-butane tetracarboxylic dianhydride

CA-6: 1,2,4,5-pentane tetracarboxylic dianhydride

CA-7: hydrazine [3.3.0] octane-2,4,6,8-tetracarboxylic dianhydride

DA-1: bis(4-aminophenoxy)methane

DA-2: 1,3-bis(4-aminophenoxy)propane

DA-3: 1,5-bis(4-aminophenoxy)pentane

<Measurement of molecular weight of polyimine precursor and quinone imidized polymer>

The molecular weight of the polyimine precursor and the ruthenium iodide polymer in the synthesis example is a room temperature gel permeation chromatography (GPC) apparatus (GPC-101) (manufactured by Showa Denko Co., Ltd.) and a column (KD-803, KD-805) (manufactured by Shodex Co., Ltd.) was measured as follows.

Column temperature: 50 ° C

Dissolution: N,N'-dimethylformamide (as additive, lithium bromide-hydrate (LiBr.H ₂ O) 30 mmol / L (liter), phosphoric acid. Anhydrous crystal (o-phosphoric acid) 30 mmol / L, tetrahydrofuran (THF) 10ml/L)

Flow rate: 1.0ml/min

Standard curve preparation standard sample: TSK standard polyethylene oxide molecular weight; about 900,000, 150,000, 100,000, and 30,000) (manufactured by Tosoh Corporation) and polyethylene glycol (molecular weight; about 12,000, 4,000, and 1,000) (manufactured by Polymer Laboratory).

(Determination of oxime imidization rate of ruthenium iodide polymer)

The oxime imidization ratio of the ruthenium iodide polymer in the synthesis example was measured as follows. Put 20 mg of ruthenium iodide polymer powder into NMR (nuclear magnetic resonance) sample tube (NMR sampling tube standard, 5 (manufactured by Kusano Scientific Co., Ltd.), a solution of dimethyl hydrazine (DMSO-d6, 0.05% by mass of TMS (tetramethyl decane)) (0.53 ml) was added, and ultrasonic waves were input to completely dissolve it. This solution was measured for proton NMR at 500 MHz using an NMR measuring machine (JNW-ECA500) (manufactured by Japan Datum Co., Ltd.). The ruthenium imidization rate is identified by using protons having no change in structure before and after imidization as a reference proton, and the absorption peak integral value of the proton and the NH group derived from proline from 9.5 ppm to 10.0 ppm. The proton absorption peak integral value is obtained by the following formula.

醯 imidization rate (%) = (1-α.x/y) × 100

In the above formula, x is the integral value of the proton absorption peak of the NH group derived from proline, y is the integral value of the absorption peak of the reference proton, and α is the polyamine acid (the imidization ratio is 0%), for 1 The ratio of the number of reference protons of the NH proton of proline.

[Synthesis Example 1]

Into a 100 ml four-necked flask equipped with a stirring device and a nitrogen introduction tube, DA-1 (6.9 g, 30 mmol) was placed, and NMP (82.3 g) was added and fed. The nitrogen gas was stirred and dissolved. CA-1 (5.9 g, 27 mmol) was added while stirring the diamine solution, and 9.1 g of NMP was further added thereto, and the mixture was stirred at 50° C. for 12 hours in an oil atmosphere under a nitrogen atmosphere to obtain a resin solid content concentration of 12% by mass. Polylysine solution. The viscosity of the polyaminic acid solution at 68 ° C was 68 mPa after confirmation by an E-type viscosity meter (manufactured by Toki Sangyo Co., Ltd.). s. The molecular weight of the poly-proline was Mn = 8,500 and Mw = 22,900.

[Synthesis Example 2]

DA-1 (136.5 g, 593 mmol) was placed in a 2000 ml four-necked flask equipped with a stirring device and a nitrogen introduction tube, and 2.82.8 g of NMP was added thereto, and the mixture was stirred and dissolved while supplying nitrogen gas. While stirring the diamine solution, CA-2 (166.1 g, 564.5 mmol) was added, and 170.3 g of NMP was further added thereto, and the mixture was stirred at 50 ° C for 12 hours in an oil atmosphere to obtain a resin solid content concentration of 15% by mass. Poly-proline solution. The polyamic acid solution has a viscosity of 504 mPa at 25 ° C. s. The molecular weight of the polyamic acid was Mn = 12,000 and Mw = 30,300.

[Synthesis Example 3]

DA-1 (20.5 g, 89.0 mmol) was added to a 300 ml four-necked flask equipped with a stirring device and a nitrogen introduction tube, and 21.43 g of NMP was added thereto, and the mixture was stirred and dissolved while supplying nitrogen gas. CA-3 (16.2 g, 82.8 mmol) was added while stirring the diamine solution, and 53.6 g of NMP was further added thereto, and the mixture was stirred at 23 ° C for 12 hours in a nitrogen atmosphere to obtain a tree. A polyamic acid solution having a lipid solid content of 12% by mass. The polyamic acid solution has a viscosity of 72 mPa at 25 ° C. s.

[Synthesis Example 4]

CA-4 (7.5 g, 29.1 mmol) was mixed with 135.8 g of NMP in a 200 ml four-necked flask equipped with a stirring apparatus and a nitrogen introduction tube, and triethylamine (6.4 g, 63 mmol) and DA were added thereto. -1 (6.9 g, 30 mmol), stirred and dissolved.

While stirring the solution, diphenyl(2,3-dihydro-2-thioxo-3-benzoxazolyl)phosphonate (24.2 g, 63 mmol) was added, and NMP 18.7 g was further added thereto. The mixture was stirred for 15 hours at a temperature to obtain a solution of a polyphthalate. The polyglycolate solution has a viscosity of 110 mPa at a temperature of 25 ° C. s.

The polyamine solution was poured into isopropyl alcohol (1,196.7 g), and the resulting precipitate was separated by filtration. The precipitate was washed with isopropyl alcohol, and then dried under reduced pressure at a temperature of 100 ° C to obtain a polyphthalate powder. The molecular weight of the polyphthalate was Mn = 9,900 and Mw = 21,800.

[Synthesis Example 5]

DA-1 (97.92 g, 425.3 mmol) was placed in a 2000 ml four-necked flask equipped with a stirring device and a nitrogen introduction tube, and 924.8 g of NMP was added thereto, and the mixture was stirred and dissolved while supplying nitrogen gas. Add CA-5 (83.41 g, 420.7 mmol) while stirring the diamine solution, and further add NMP 102.8 g was stirred in an oil bath at 50 ° C for 12 hours in a nitrogen atmosphere to obtain a polyaminic acid solution having a resin solid concentration of 15% by mass. The polyamic acid solution has a viscosity of 172 mPa at 25 ° C. s. Further, the molecular weight of the polyamic acid was Mn = 9,800 and Mw = 19,600.

[Synthesis Example 6]

After adding NMP to the polyamic acid solution (562.0 g) obtained in Synthesis Example 5 and diluting to 6 mass%, acetic anhydride (197.5 g) and pyridine (76.6 g) were added as a ruthenium catalyzed catalyst at 50 The reaction was carried out for 5 hours at °C. The reaction solution was poured into methanol (5772 ml), and the obtained precipitate was separated by filtration. The precipitate was washed with methanol, and dried under reduced pressure at 100 ° C to obtain a succinimide polymer powder. The ruthenium iodide polymer had an oxime imidization ratio of 84%, a number average molecular weight of 9,800, and a weight average molecular weight of 19,300.

[Synthesis Example 7]

DA-1 (8.1 g, 35 mmol) was placed in a 100 ml four-necked flask equipped with a stirring device and a nitrogen introduction tube, and 76.7 g of NMP was added thereto, and the mixture was stirred and dissolved while supplying nitrogen gas. CA-6 (7.0 g, 32.9 mmol) was added while stirring the diamine solution, and 8.52 g of NMP was further added thereto, and the mixture was stirred at 40 ° C for 12 hours in a nitrogen atmosphere to obtain a resin solid concentration of 15% by mass. Proline solution. The polyamic acid solution has a viscosity of 192 mPa at 25 ° C. s. The molecular weight of the poly-proline was Mn = 8,300 and Mw = 23,700.

[Synthesis Example 8]

DA-1 (5.9 g, 26.0 mmol) was placed in a 100 ml four-necked flask equipped with a stirring device and a nitrogen introduction tube, and N9.9 (79.9 g) was added thereto, and the mixture was stirred and dissolved while supplying nitrogen gas. While stirring the diamine solution, CA-7 (6.1 g, 24.4 mmol) was added, and 8.9 g of NMP was further added thereto, and the mixture was stirred at 50 ° C for 12 hours in an oil atmosphere to obtain a resin solid content concentration of 12% by mass. Poly-proline solution. The polyamic acid solution has a viscosity of 72 mPa at 25 ° C. s.

[Synthesis Example 9]

In a 1000 ml four-necked flask equipped with a stirring device and a nitrogen introduction tube, DA-2 (51.7 g, 200 mmol) was placed, and 672 g of NMP was added thereto, and the mixture was stirred and dissolved while supplying nitrogen gas. CA-1 (41.7 g, 191.2 mmol) was added while stirring the diamine solution, and 168.1 g of NMP was further added thereto, and the mixture was stirred at 50 ° C for 24 hours in a nitrogen atmosphere to obtain a solid concentration of the resin of 12% by mass. Proline solution. The polyamic acid solution has a viscosity of 135 mPa at 25 ° C. s. Further, the molecular weight of the polyamic acid was Mn = 12,600 and Mw = 30,900.

[Synthesis Example 10]

DA-3 (6.9 g, 24 mmol) was placed in a 100 ml four-necked flask equipped with a stirring device and a nitrogen introduction tube, and 80.0 g of NMP was added thereto, and the mixture was stirred and dissolved while supplying nitrogen gas. While stirring the diamine solution CA-1 (5.0 g, 23 mmol) was added, and NMP was added until the solid content concentration became 12% by mass, and the mixture was stirred overnight at 50 ° C using an oil bath to obtain a solution of polyglycine. The polyamic acid solution has a viscosity of 525 mPa at 25 ° C. s. Further, the molecular weight of the polyamic acid was Mn = 14,800 and Mw = 32,500.

[Example 1]

To 50.0 g of the polyamidic acid solution obtained by the synthesis method of Synthesis Example 1, 19.0 g of NMP, 6.0 g of NMP solution containing 1.0% by weight of 3-aminopropyltriethoxysilane, and BCS 25.0 g were placed. A liquid crystal alignment agent (A-1) having a concentration of 6 mass% was obtained. No abnormality such as turbidity or precipitation of the liquid crystal alignment agent (A-1) was observed, and it was confirmed that it was a uniform solution.

[Example 2]

To 40.0 g of polylysine dissolved in the synthesis method of Synthesis Example 2, 29.0 g of NMP, 6.0 g of NMP solution containing 1.0% by weight of 3-aminopropyltriethoxysilane, and BCS 25.0 g were added. A liquid crystal alignment agent (A-2) having a concentration of 6 mass% was obtained. No abnormality such as turbidity or precipitation of the liquid crystal alignment agent (A-2) was observed, and it was confirmed that it was a uniform solution.

[Example 3]

To 50.0 g of the polyamidic acid solution obtained in the synthesis method of Synthesis Example 3, 19.0 g of NMP was added, and 3-aminopropyltriethoxydecane was contained. 6.0 g of a 1.0% by weight NMP solution and 25.0 g of BCS were used to obtain a liquid crystal alignment agent (A-3) having a concentration of 6 mass%. No abnormality such as turbidity or precipitation was observed in the liquid crystal alignment agent (A-3), and it was confirmed to be a uniform solution.

[Example 4]

NMP (113.3 g) was added to the polyphthalate powder (10.0 g) obtained in the synthesis method of Synthesis Example 4, and the mixture was stirred and dissolved at 23 ° C for 12 hours. To the solution, 10.0 g of a NMP solution containing 1.0% by weight of 3-aminopropyltriethoxydecane and BCS (33.3 g) were added, and the mixture was stirred at 23 ° C for 2 hours to obtain a liquid crystal alignment agent (A-4). No abnormality such as turbidity or precipitation was observed in the liquid crystal alignment agent (A-4), and it was confirmed to be a homogeneous solution.

[Example 5]

To 40.0 g of the polyamidic acid solution obtained in the synthesis method of Synthesis Example 5, 29.0 g of NMP, 6.0 g of NMP solution containing 1.0% by weight of 3-aminopropyltriethoxydecane, and BCS 25.0 g were added. A liquid crystal alignment agent (A-5) having a concentration of 6 mass% was obtained. No abnormality such as turbidity or precipitation of the liquid crystal alignment agent (A-5) was observed, and it was confirmed that it was a uniform solution.

[Example 6]

NMP (113.3 g) was added to the ruthenium iodide polymer powder (10.0 g) obtained in the synthesis method of Synthesis Example 6, and the mixture was stirred and dissolved at 23 ° C for 12 hours. Adding 3-aminopropyltriethyl to the solution 10.0 g of an NMP solution of 1.0% by weight of oxydecane and BCS (33.3 g) were stirred at 23 ° C for 2 hours to obtain a liquid crystal alignment agent (A-6). No abnormality such as turbidity or precipitation of the liquid crystal alignment agent (A-6) was observed, and it was confirmed that it was a uniform solution.

[Example 7]

To 40.0 g of the polyamic acid solution obtained in the synthesis method of Synthesis Example 7, 29.0 g of NMP, 6.0 g of a NMP solution containing 1.0% by weight of 3-aminopropyltriethoxysilane, and BCS 25.0 g were placed. A liquid crystal alignment agent (A-7) having a concentration of 6 mass% was obtained. No abnormality such as turbidity or precipitation of the liquid crystal alignment agent (A-7) was observed, and it was confirmed that it was a uniform solution.

[Example 8]

To 50.0 g of the polyamidic acid solution obtained in the synthesis method of Synthesis Example 8, 19.0 g of NMP, 6.0 g of NMP solution containing 1.0% by weight of 3-aminopropyltriethoxydecane, and BCS 25.0 g were added. A liquid crystal alignment agent (A-8) having a concentration of 6 mass% was obtained. No abnormality such as turbidity or precipitation of the liquid crystal alignment agent (A-8) was observed, and it was confirmed that it was a uniform solution.

[Comparative Example 1]

To 50.0 g of the polyamidic acid solution obtained in the synthesis method of Synthesis Example 9, 19.0 g of NMP, 6.0 g of NMP solution containing 1.0% by weight of 3-aminopropyltriethoxydecane, and BCS 25.0 g were added. A liquid crystal alignment agent (B-1) having a concentration of 6 mass% was obtained. The liquid crystal alignment agent (B-1) is not An abnormal image such as the occurrence of turbidity or precipitates was observed, and it was confirmed to be a homogeneous solution.

[Comparative Example 2]

To 50.0 g of the polyamidic acid solution obtained by the synthetic method of Synthesis Example 10, 19.0 g of NMP, 6.0 g of a NMP solution containing 1.0% by weight of 3-aminopropyltriethoxydecane, and 25.0 g of BCS were added. Liquid crystal alignment agent (B-2) having a concentration of 6 mass%. No abnormality such as turbidity or precipitation of the liquid crystal alignment agent (B-2) was observed, and it was confirmed that it was a uniform solution.

<Production of adhesion evaluation sample>

The obtained liquid crystal alignment agent was filtered through a 1.0 μm filter, spin-coated on a glass substrate with a transparent electrode, dried on a hot plate at 80° C. for 2 minutes, and then fired at 230° C. for 20 minutes to obtain a film. A coating film having a thickness of 100 nm. Two substrates thus obtained were prepared, and a 4 μm bead spacer was spread on the liquid crystal alignment film surface of one of the substrates, and then a sealant (XN-1500T manufactured by Kyoritsu Chemical Co., Ltd.) was dropped. Next, the liquid crystal alignment film surface of the other substrate was set to the inside, and the overlap width of the bonded substrate was 1 cm. At this time, the amount of the sealant dropped was adjusted until the diameter of the sealant after the bonding became about 3 mm. The two bonded substrates were fixed by a clip, and then thermally cured at 120 ° C for 1 hour to prepare a sample for evaluation of adhesion.

<Measurement of force>

The prepared sample was fixed to the upper and lower substrate end portions by a table type precision universal testing machine AGS-X 500N manufactured by Shimadzu Corporation, and then pressed in from the upper portion of the center portion of the substrate, and the pressure (N) at the time of peeling was measured. The evaluation of the adhesion force was carried out using a value normalized by the pressure (N) by the area (mm ² ) estimated from the diameter of the measured sealant.

The results of the adhesions performed by the liquid crystal alignment agents A-1 to A-8 and B-1 to B-2 are shown in Table 1.

<Production of liquid crystal cell>

The obtained liquid crystal alignment agent was filtered through a 1.0 μm filter, spin-coated on a glass substrate with a transparent electrode, dried on a hot plate at 80° C. for 2 minutes, and then fired at 230° C. for 20 minutes to obtain a film. A coating film having a thickness of 100 nm. The ruthenium-imidized polymer film was rubbed with a rayon cloth (roll diameter: 120 mm, rotation speed: 1000 rpm, moving speed: 20 mm/sec, and press-in amount: 0.4 mm), and then subjected to ultrasonic irradiation for 1 minute in pure water. Dry at °C for 10 minutes. Two sheets of the substrate with the liquid crystal alignment film are prepared, and after the spacer of 4 μm is disposed on the liquid crystal alignment film surface of one of the substrates, the flat grinding directions of the two substrates are combined in an antiparallel manner, leaving The lower liquid crystal injection port is sealed, and the surrounding is sealed and combined into an empty cell with a cell unit gap of 4 μm. The liquid crystal of the unit cell (MLC-2041, manufactured by Mok) was vacuum-injected at a normal temperature, and an anti-parallel liquid crystal cell was obtained by sealing the injection port.

<Liquid alignment]

The alignment state of the liquid crystal cell was observed under a polarizing microscope, and those who had no alignment defects were evaluated as "good", and those who had alignment defects were evaluated as "poor".

<Measurement of pretilt angle>

The liquid crystal cell was heated at 110 ° C for 30 minutes, and then the pretilt angle was measured. The measurement was performed using an Axo Scan Mueller matrix polarizer manufactured by Opt-metrics.

Table 2 shows the results of the pretilt angle and the alignment of the liquid crystal alignment agents A-1 to A-8 and B-1 to B-2.

[Industrial Applicability]

The liquid crystal alignment agent of the present invention is industrially useful for improving the display unevenness in the vicinity of the bezel by improving the adhesion between the encapsulant and the liquid crystal alignment film in the narrow bezel liquid crystal display device which can ensure a large number of display surfaces.

Claims (8)

A liquid crystal alignment agent comprising a polyamidimide precursor selected from the group consisting of reacting a diamine component with a tetracarboxylic acid derivative, and a ruthenium imidization polymerization for the ruthenium imidization of the polyimide precursor At least one of the substances, the polyimine precursor is a repeating unit having the following formula (1); In the formula (1), Y is a divalent organic group derived from a diamine component, X is a tetravalent organic group derived from a tetracarboxylic acid derivative, and each of A ¹ and A ^{2 is} independently a hydrogen atom or a carbon which may have a substituent An alkyl group having 1 to 10 carbon atoms, an alkenyl group having 1 to 10 carbon atoms which may have a substituent, an alkynyl group having 1 to 10 carbon atoms which may have a substituent, and R ¹ being a hydrogen atom or an alkyl group having 1 to 10 carbon atoms. At least a part of Y is a structure of the following formula (2); The liquid crystal alignment agent of claim 1, wherein in the repeating unit represented by the above formula (1), at least a part of X is a tetravalent organic group having an alicyclic structure or an aliphatic structure. The liquid crystal alignment agent of claim 2, wherein in the repeating unit represented by the above formula (1), at least a part of X is a structure selected from the following (X-9), (X-26), (X-27) ; The liquid crystal alignment agent of claim 2, wherein in the repeating unit represented by the above formula (1), X is a ratio of a tetravalent organic group having an alicyclic structure or an aliphatic structure of 10 to 100 mol%. The liquid crystal alignment agent of claim 3, wherein in the repeating unit represented by the above formula (1), X is a ratio of any one of (X-9), (X-26), and (X-27) is 10~ 100% by mole. The liquid crystal alignment agent of claim 1, wherein in the repeating unit represented by the above formula (1), the ratio of the structure of Y to the formula (2) is 10 to 100 mol%. A liquid crystal alignment film obtained by applying a liquid crystal alignment agent according to any one of claims 1 to 6 to a substrate and baking it. A liquid crystal display element characterized by having the liquid crystal alignment film of claim 7.