TW201922853A - Liquid crystal alignment agent, liquid crystal alignment film, and liquid crystal display element - Google Patents

Abstract

This liquid crystal alignment agent contains an organic solvent and at least one polymer selected from polyimide precursors which are a reaction product of a tetracarboxylic acid derivative and a diamine, and polyimides which are imidization products of the polyimide precursors, wherein the organic solvent contains component A which is at least one selected from [gamma]-butyrolactone and [gamma]-valerolactone, and component B which is at least one selected from dipropylene glycol dimethyl ether and diacetone alcohol, the contained amounts of component A and component B are both not more than 25 wt%, and the difference between the contained amounts of component A and component B is 5 wt% or less.

Description

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

The present invention relates to a liquid crystal alignment agent, a liquid crystal alignment film, and a liquid crystal display element suitable for coating by an inkjet method (hereinafter, referred to as inkjet coating).

Liquid crystal alignment films are widely used as a polyimide-based liquid crystal alignment agent that is coated with a polyimide precursor such as polyamic acid or a solution of a soluble polyimide as a main component and is fired. Liquid crystal alignment film. As a film-forming method of the liquid crystal alignment film, instead of the spin coating, flexographic printing, etc., hitherto, inkjet coating has gradually become the mainstream.

Inkjet coating is a method in which fine droplets are dropped on a substrate, and the droplets are wetted and diffused to form a film. By this method, the liquid crystal alignment agent can be efficiently used in the manufacturing process of the liquid crystal panel, the production efficiency of the liquid crystal panel is improved, and thus the cost of the liquid crystal panel can be reduced.

For the liquid crystal alignment agent used for inkjet coating, it is required that the film thickness in the inner part of the coating surface is not small, and the film forming accuracy in the peripheral part is high. At the same time, it is also important that the organic solvent in the liquid crystal alignment agent does not cause damage to the inkjet head or peripheral members when it is ejected from the inkjet device.

In order to achieve the above-mentioned various requirements, liquid crystal alignment agents for inkjet coating using an appropriate combination of various solvents have been proposed (see Patent Documents 1 and 2). However, with the recent advances in the definition and size of liquid crystal display elements, , And expected features are even more improved.
[Prior technical literature]
[Patent Literature]

[Patent Document 1] Japanese Patent Application No. 2013-507817
[Patent Document 2] Japanese Patent Application No. 2014-529512

[Problems to be Solved by the Invention]

In view of the above background, the present invention aims to provide a liquid crystal alignment agent most suitable for inkjet coating by improving various characteristics required for inkjet coating.

In order to achieve the above-mentioned object, the inventors and the like have found that the liquid crystal alignment agent composed of the following structure is most suitable for achieving the above-mentioned result, and completed the present invention.

[Means to solve the problem]

Therefore, the present invention has been completed based on the above-mentioned knowledge, and has the following gist.
A liquid crystal alignment agent, comprising a polymer and an organic solvent, wherein the polymer is at least one polyimide precursor selected from the reactant of a tetracarboxylic acid derivative and a diamine, and a polyimide thereof Polyimide,
The organic solvent contains
Component A: at least one selected from γ-butyrolactone and γ-valerolactone,
Component B: Dipropylene glycol dimethyl ether;
In addition, the contents of the A component and the B component are each 25% by weight or less, and the difference between the contents of the A component and the B component is 5% by weight or less.

[Effect of the invention]

By using the liquid crystal alignment agent of the present invention, in the case of inkjet coating, a liquid crystal alignment film having a small film thickness in the coating surface portion and a high film forming accuracy in the coating peripheral portion can be obtained, and At the same time, when the liquid crystal alignment agent is ejected from the inkjet device, the inkjet head or peripheral members are not damaged, and as a result, it becomes possible to impart stability to the manufacture of the liquid crystal display element.

Hereinafter, various requirements regarding the present invention will be described in detail.

＜ Organic solvents and their composition ＞
The liquid crystal alignment agent of this invention contains the following A and B components as an organic solvent.
Component A: at least one selected from γ-butyrolactone and γ-valerolactone
Component B: Dipropylene glycol dimethyl ether
The organic solvent of component A is a polymer that dissolves the polymer contained in the liquid crystal alignment agent of the present invention, and also does not easily affect the inkjet head or peripheral components of the inkjet coating device. As A component, γ-butyrolactone is preferable.
The solvent of the B component is one that improves the wet diffusibility when the liquid crystal alignment agent of the present invention is applied to a substrate or a film.
The contents of the A component and the B component are each 25% by weight or less, and the difference between the contents of the A component and the B component is 5% by weight or less.
From the viewpoint of solubility, the component C is further included: at least one selected from the group consisting of N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, and N-butyl-2-pyrrolidone One is better.
The organic solvent of component C is a component which dissolves the polymer contained in the liquid crystal aligning agent of this invention. Preferred examples include N-methyl-2-pyrrolidone and N-ethyl-2-pyrrolidone.
When the component C is used, its content is preferably 35% by weight or less, and more preferably 30% by weight or less based on the total weight of the liquid crystal alignment agent.

＜ Polymer ＞
The polymer contained in the liquid crystal alignment agent of the present invention is at least one polymer selected from the group consisting of a polyimide precursor of a reaction product of a tetracarboxylic acid derivative and a diamine, and a polyimide of the fluorenimide.
The structure of the above polymer is not particularly limited. According to the characteristics of the obtained liquid crystal alignment agent, a tetracarboxylic acid derivative and a diamine described later can be arbitrarily selected, and from the viewpoint of solubility and the like, the following formula [1- 1] A polymer having a side chain structure is preferred.

In Formula [1-1], Y ¹ and Y ³ each independently represent a single bond,-(CH ₂ ) _a- (a is an integer of 1 to 15), -O-, -CH ₂ O-,- COO- and -OCO- are grouped into one species.

Y ² represents a single bond or-(CH ₂ ) _b- (b is an integer from 1 to 15) (However, when Y ¹ or Y ³ is a single bond and-(CH ₂ ) _a- , Y ² is a single bond; Y ¹ is at least one selected from the group consisting of -O-, -CH ₂ O-, -COO-, and -OCO-, and / or Y ³ is selected from -O-, -CH ₂ O-, -COO When at least one of-and -OCO- groups, Y ² is a single bond or-(CH ₂ ) _b- ).

Y ⁴ represents at least one type of divalent cyclic group selected from the group consisting of a benzene ring, a cyclohexane ring, and a heterocyclic ring, or a divalent organic group having 17 to 51 carbon atoms having a steroid skeleton, and the aforementioned cyclic group Any of the above hydrogen atoms can be passed through an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a fluorine-containing alkyl group having 1 to 3 carbon atoms, a fluorine-containing alkoxy group having 1 to 3 carbon atoms, or Replaced by a fluorine atom.

Y ⁵ represents at least one cyclic group selected from the group consisting of a benzene ring, a cyclohexane ring, and a heterocyclic ring, and any hydrogen atom on these cyclic groups may pass through an alkyl group or carbon having 1 to 3 carbon atoms; The alkoxy group having 1 to 3 carbon atoms, the fluoroalkyl group having 1 to 3 carbon atoms, the fluorinating alkoxy group having 1 to 3 carbon atoms or fluorine atoms are substituted.

Y ⁶ is selected from the group consisting of an alkyl group having 1 to 18 carbon atoms, an alkenyl group having 2 to 18 carbon atoms, a fluorine-containing alkyl group having 1 to 18 carbon atoms, an alkoxy group having 1 to 18 carbon atoms, and an alkyl group having 1 to 18 carbon atoms. At least one species of a group containing a fluorine-containing alkoxy group. n represents an integer from 0 to 4.
Examples of the method for introducing the side chain structure into the polymer include a method of introducing the side chain structure into a polymer material using a tetracarboxylic acid derivative or a diamine. Among them, from the viewpoint of ease of synthesis and the like, it is preferable to use a diamine to which the above-mentioned side chain structure has been introduced.
As a preferable specific example of the said side chain structure, the following formulas (S1-1)-(S1-22) are mentioned.

In addition, when the manufacturing steps of the liquid crystal display element include a process such as ultraviolet irradiation, it is preferable to introduce a photoreactive side chain that causes a photoreaction by ultraviolet rays of a specific wavelength.

Examples of the photoreactive side chain include a side chain structure of the following formula [VII]. The side chain structure of the formula [VII] has a radical generating structure. In the radical generating structure, ultraviolet rays are irradiated to decompose and generate radicals.

In the above formula [VII], Ar represents at least one aromatic hydrocarbon group selected from the group consisting of a phenylene group, a naphthyl group, and a biphenylene group, and the hydrogen atom of these rings may be substituted by a halogen atom. Ar, which is bonded to a carbonyl group, interferes with the absorption wavelength of ultraviolet rays, and in the case of a long wavelength, a structure having a longer conjugate length such as a naphthyl group or a diphenyl group is preferred. On the other hand, when Ar has a structure such as a naphthyl group or a biphenylene group, solubility may be deteriorated. In this case, the difficulty of synthesis becomes high. If the wavelength of ultraviolet rays is in the range of 250 nm to 380 nm, sufficient characteristics can be obtained even if it is a phenyl group, so Ar is preferably a phenyl group.

In the Ar, a substituent may be provided on the aromatic hydrocarbon group. As examples of the substituent herein, an electron-donating organic group such as an alkyl group, a hydroxyl group, an alkoxy group, or an amine group is preferred.

In the formula [VII], R ₁ and R ₂ are each independently an alkyl group, alkoxy group, benzyl group, or phenethyl group having 1 to 10 carbon atoms. In the case of an alkyl group or an alkoxy group, a ring may be formed by R ₁ and R ₂ .

In the above formula [VII], T ₁ and T ₂ are each independently represented, a single bond, -O-, -COO-, -OCO-, -NHCO-, -CONH-, -NH-, -CH ₂ O -, -N (CH ₃ )-, -CON (CH ₃ )-or -N (CH ₃ ) CO-.

In Formula [VII], S represents a single bond, an unsubstituted or an alkylene group having 1 to 20 carbon atoms which may be substituted with a fluorine atom. The -CH ₂ -or -CF ₂ -of the alkylene group herein may also be optionally substituted with -CH = CH-, and in the case where it is not adjacent to any of the groups listed below, -O-, -COO-, -OCO-, -NHCO-, -CONH-, -NH-, a divalent carbocyclic ring, a divalent heterocyclic ring.

In the formula [VII], Q represents a structure selected from the following formula (1d).

In the formula (1d), R represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. R ₃ represents -CH _2- , -NR-, -O-, or -S-.

In the above formula [VII], Q is preferably an electron-donating organic group, and an alkyl group, a hydroxyl group, an alkoxy group, an amine group, or the like, which is also exemplified in the example of Ar, is more preferable. When Q is an amine-based derivative, during the polymerization of the polyfluorene acid of the polyfluorine imide precursor, there may be a possibility that a bad situation such as the formation of a salt between the carboxylic acid group and the amine group may occur. Hydroxyl or alkoxy is preferred.

<Tetracarboxylic acid derivative>
The polymer contained in the liquid crystal alignment agent of the present invention is at least one polymer selected from the group consisting of a polyimide precursor obtained from a reaction of a tetracarboxylic acid derivative and a diamine, and a polyimide of a fluorimidate. . Hereinafter, specific examples of the materials used and the manufacturing method will be described in detail.
Examples of the tetracarboxylic acid derivatives used in the production of polyimide precursors include not only tetracarboxylic dianhydrides, but also tetracarboxylic acids such as their derivatives, tetracarboxylic dihalide compounds, and tetracarboxylic acids. Acid dialkyl ester, tetracarboxylic acid dialkyl ester dihalide.
Among the tetracarboxylic acid derivatives, those represented by the following formula (3) are preferred.

In the formula (3), the structure of X ₁ is not particularly limited. Specific examples include the following formulae (X1-1) to (X1-42). Preferred are (X1-1), (X1-2), (X1-5), (X1-7), (X1-8), (X1-10), (X1-11), (X1-26) ), (X1-27), (X1-33), (X1-38), (X1-40).

In the formulae (X1-1) to (X1-4), R ₃ to R ₂₃ each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, or 2 carbon atoms. An alkynyl group of ~ 6, a monovalent organic group of 1 to 6 carbon atoms containing a fluorine atom, or a phenyl group. From the viewpoint of liquid crystal alignment, R ₃ to R ₂₃ are preferably a hydrogen atom, a halogen atom, a methyl group, or an ethyl group, and more preferably a hydrogen atom or a methyl group.
Specific examples of the formula (X1-1) include the following formulas (X1-1-1) to (X1-1-6). From the viewpoint of liquid crystal alignment and polymerization reactivity, (X1-1-1) and (X1-1-2) are particularly preferred.

＜ Diamine ＞
The diamine used in the production of the polyfluorene imide precursor is represented by the following formula (4).

In the formula (4), A ₁ and A ₂ each independently represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, or an alkynyl group having 2 to 5 carbon atoms.
The structure of the above formula (4) is not particularly limited. As a preferable structure, the diamine containing the side chain structure of Formula [1-1] as mentioned above is mentioned. Specific examples thereof include (Y-178), (Y-180), and (Y-181).
Alternatively, a diamine having an arbitrary structure can be used. Specific examples include the following (Y-1) to (Y-177).
From the viewpoints of ease of production of the polyimide precursor, stability of the liquid crystal alignment agent, and characteristics of the liquid crystal alignment film, etc., (Y-27), (Y-28), (Y-38), ( Y-71), (Y-72), (Y-76), (Y-77), (Y-80), (Y-81), (Y-82), (Y-158), (Y- 159), (Y-160), (Y-161), (Y-169) to (Y-188) are preferred.

In the above formula, Me represents a methyl group, and R ¹ represents a hydrogen atom or a hydrocarbon group having 1 to 5 carbon atoms.

＜ Polyamine acid ＞
The polyamido acid of the polyamido precursor used in the present invention can be produced by the method shown below. Specifically, by reacting tetracarboxylic dianhydride and diamine in the presence of an organic solvent at a temperature of -20 ° C to 150 ° C, preferably 0 ° C to 50 ° C, the reaction is allowed to proceed for 30 minutes to 24 hours. The best reaction is 1 to 12 hours for synthesis.

From the viewpoint of the solubility of the monomers and polymers, the organic solvent used in the above reaction is preferably N, N-dimethylformamidine, N-methyl-2-pyrrolidone, or γ-butyrolactone. These can be used alone or in combination of two or more. The concentration of the polymer is preferably from 1 to 30% by mass, and more preferably from 5 to 20% by mass from the viewpoint that it is difficult to cause precipitation of the polymer and it is easy to obtain a high molecular weight body.

With the polyamic acid obtained as described above, the polymer can be precipitated and recovered by well stirring the reaction solution and injecting a poor solvent at the same time. In addition, several times of precipitation, washing with a poor solvent, and drying at room temperature or heating to obtain a purified polyamic acid powder can be obtained. The lean solvent is not particularly limited, and examples thereof include water, methanol, ethanol, hexane, butyl cellosolve, acetone, and toluene.

＜ Polyamidate ＞
A polyamidate which is one of the polyimide precursors used in the present invention can be produced by a method (I), (II), or (III) shown below.

(I) In the case of production from polyamic acid Polyamines can be synthesized by esterifying a polyamino acid obtained from a tetracarboxylic dianhydride and a diamine. Specifically, it is possible to react the polyamic acid and the esterifying agent in the presence of an organic solvent at a temperature of -20 ° C to 150 ° C, preferably 0 ° C to 50 ° C, for 30 minutes to 24 hours, preferably The reaction takes 1 to 4 hours to synthesize.

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

From the viewpoint of the solubility of the polymer, the solvent used in the above reaction is preferably N, N-dimethylformamide, N-methyl-2-pyrrolidone, or γ-butyrolactone. One type can be used or two or more types can be mixed and used. The polymer concentration in the reaction solution is preferably from 1 to 30% by mass, and more preferably from 5 to 20% by mass from the viewpoint that it is not easy to cause polymer precipitation and it is easy to obtain a high molecular weight body.

(II) In the case of production by the reaction of a tetracarboxylic acid diester dichloride and a diamine, a polyamidate system can be produced from a tetracarboxylic acid diester dichloride and a diamine. Specifically, the tetracarboxylic acid diester dichloride and diamine can be reacted in the presence of a base and an organic solvent at -20 ° C to 150 ° C, preferably at 0 ° C to 50 ° C, for 30 minutes ~ 24 hours, preferably 1 to 4 hours for synthesis.

As the base, for example, pyridine, triethylamine, 4-dimethylaminopyridine and the like can be used, but in order to make the reaction proceed gently and stably, pyridine is preferred. The amount of the alkali to be used is preferably from 2 to 4 times the mole of the tetracarboxylic acid diester dichloride from the viewpoint of being easily removed and easily obtaining a high molecular weight body.

From the viewpoint of the solubility of the monomers and polymers, the solvent used in the above reaction is preferably N-methyl-2-pyrrolidone or γ-butyrolactone. One of these solvents can be used or the Two or more types are mixed and used. The polymer concentration in the reaction solution is preferably from 1 to 30% by mass, and more preferably from 5 to 20% by mass from the viewpoint that it is not easy to cause polymer precipitation and it is easy to obtain a high molecular weight body. In addition, in order to prevent the hydrolysis of the tetracarboxylic acid diester dichloride, it is better that the solvent used for the synthesis of the polyamidate is dehydrated as much as possible, and it is also preferable to prevent the mixing of external air in a nitrogen environment.

(III) In the case where it is produced by the reaction of a tetracarboxylic acid diester and a diamine, a polyamidate system can be produced by polycondensing a tetracarboxylic acid diester and a diamine. Specifically, a tetracarboxylic diester and a diamine are reacted in the presence of a condensing agent, a base, and an organic solvent at a temperature of 0 ° C to 150 ° C, preferably 0 ° C to 100 ° C, for 30 minutes to 24 minutes. It is preferably produced by reacting for 3 to 15 hours.

Examples of the aforementioned condensing agent include triphenylphosphite, dicyclohexylcarbodiimide, 1-ethyl-3- (3-dimethylaminopropyl) carbodiimide hydrochloride, N , N'-carbonyldiimidazole, dimethoxy-1,3,5-triazinylmethylmorpholinium, tetrafluoroborate O- (benzotriazol-1-yl) -N, N, N ' , N'-tetramethylurea salt, hexafluorophosphate O- (benzotriazol-1-yl) -N, N, N ', N'-tetramethylurea salt, (2,3-dihydro- 2-thio-3-benzoxazolyl) phosphonic acid diphenyl and the like. The addition amount of the condensing agent is preferably 2 to 3 times mole compared to the tetracarboxylic acid diester.

As the base, tertiary amines such as pyridine and triethylamine can be used. The amount of the alkali used is preferably from 2 to 4 times the mole of the diamine component from the viewpoint of being easily removed and easily obtaining a high molecular weight body.

In the above reaction, the reaction can be efficiently performed by adding a Lewis acid as an additive. As the Lewis acid, lithium halides such as lithium chloride and lithium bromide are preferred. The addition amount of the Lewis acid is preferably 0 to 1.0 times mole compared to the diamine component.

Among the above-mentioned three kinds of polyamic acid ester production methods, the synthetic method of (1) or (2) above is particularly preferable because it can obtain a high molecular weight polyamic acid ester.

The solution of the polyurethane obtained by the above operation can be used to precipitate the polymer by being well stirred and injected into a poor solvent at the same time. After carrying out precipitation several times, washing with a poor solvent, drying at room temperature or heating to obtain a purified polyurethane powder. The lean solvent is not particularly limited, and examples thereof include water, methanol, ethanol, hexane, butyl cellosolve, acetone, and toluene.

＜ Polyimide ＞
The polyimide used in the present invention can be produced by imidizing the aforementioned polyamidic acid or polyamidate. The polyimide / imidization rate used in the present invention is not limited to 100%. From the standpoint of electrical characteristics, 20 to 99% is preferred. In the case of producing polyimide from polyamic acid, an alkaline catalyst is added to a polyamic acid solution obtained by dissolving the polyamic acid solution or polyamic acid resin powder in an organic solvent. The chemical fluorene imidization is simple. Chemical ammonium imidization is preferred because the ammonium imidization reaction is performed at a relatively low temperature, and the molecular weight of the polymer is not easily reduced during the ammonium imidization process.

The chemical ammonium imidization can be carried out by stirring a polyamic acid or a polyamic acid ester to be imidized in an organic solvent in the presence of a basic catalyst and an acid anhydride. As the organic solvent, the aforementioned solvents used in the polymerization reaction can be used. Examples of the basic catalyst include pyridine, triethylamine, trimethylamine, tributylamine, and trioctylamine. Among them, pyridine is preferable because it has moderate alkalinity for the reaction to proceed. Examples of the acid anhydride include anhydrous acetic acid, anhydrous trimellitic acid, anhydrous pyromellitic acid, and the like. When anhydrous acetic acid is used, it is preferred that purification after the reaction is completed easily.

The temperature at which the amidine imidization reaction is performed is, for example, -20 ° C to 120 ° C, preferably 0 ° C to 100 ° C, and the reaction time can be performed for 1 to 100 hours. The amount of the alkaline catalyst is 0.5 to 30 mol times of the amino acid group, preferably 2 to 20 mol times, and the amount of the acid anhydride is 1 to 50 mol times of the amino acid group, preferably 3 to 30 mol times. The hydrazone imidization rate of the obtained polymer can be controlled by adjusting the amount of catalyst, temperature, and reaction time.

In the solution after the polyimide or polyimide acid imidization reaction, since the added catalyst and the like remain, the obtained imidized polymer is recovered by means described below. An organic solvent is preferably used for re-dissolving the liquid crystal alignment agent.

The polyimide solution obtained by the above operation can be used to precipitate the polymer by well stirring and simultaneously injecting into a poor solvent. After several times of precipitation and washing with a poor solvent, the powder of purified polyurethane can be obtained at room temperature or by heating and drying.

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

＜ Liquid crystal alignment agent ＞
The liquid crystal alignment agent of the present invention has a solution form in which a polymer containing a specific polymer is dissolved in an organic solvent containing a specific solvent. The molecular weights of the polyimide precursor and polyimide described in the present invention are preferably 2,000 to 500,000, more preferably 5,000 to 300,000, and more preferably 10,000 to 100,000, based on the weight average molecular weight. The number average molecular weight is preferably 1,000 to 250,000, more preferably 2,500 to 150,000, and even more preferably 5,000 to 50,000.

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

＜ Other solvents ＞
The solvent in the liquid crystal alignment agent of the present invention contains the A component and the B component described above, and it is preferable that the C component is further contained, and other solvents may also be contained. As other solvents, it is preferable to use a solvent (also called a good solvent) that can dissolve the polyimide precursor and polyimide, or improve the coating property or surface smoothness of the liquid crystal alignment film when applying the liquid crystal alignment agent. Solvent (also known as lean solvent). Specific examples of other solvents are listed below, but are not limited to these examples.

Specific examples of the good solvent include 1,3-dimethylimidazolinone, N, N-dimethylformamide, N, N-dimethylacetamide, dimethylformamide, and formazan. Methyl ethyl ketone, cyclohexanone, cyclopentanone, 3-methoxy-N, N-dimethylpropanehydrazine, 4-hydroxy-4-methyl-2-pentanone, and the like.
Specific examples of the lean solvent include 1-butoxy-2-propanol, 2-butoxy-1-propanol, 2-propoxyethanol, 2- (2-propoxyethoxy) Based) ethanol, 1-propoxy-2-propanol ethanol, isopropyl alcohol, 1-butanol, 2-butanol, isobutyl alcohol, tert-butyl alcohol, 1-pentanol, 2-pentyl alcohol Alcohol, 3-pentanol, 2-methyl-1-butanol, isopentyl alcohol, tert-pentyl alcohol, 3-methyl-2-butanol, neopentyl alcohol, 1-hexanol, 2- Methyl-1-pentanol, 2-methyl-2-pentanol, 2-ethyl-1-butanol, 1-heptanol, 2-heptanol, 3-heptanol, 1-octanol, 2- Octanol, 2-ethyl-1-hexanol, cyclohexanol, 1-methylcyclohexanol, 2-methylcyclohexanol, 3-methylcyclohexanol, 1,2-ethylene glycol, 1 2,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol , 2-methyl-2,4-pentanediol, 2-ethyl-1,3-hexanediol, dipropyl ether, dibutyl ether, dihexyl ether, dioxane, ethylene glycol dimethyl Ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, 1,2-butoxyethane, diethylene glycol dimethyl ether, diethylene glycol methyl ethyl ether, diethyl ether Glycol dibutyl ether, 2-pentanone 3-pentanone, 2-hexanone, 2-heptanone, 4-heptanone, 3-ethoxybutyl acetate, 1-methylpentyl acetate, 2-ethylbutyl acetate , 2-ethylhexyl acetate, ethylene glycol monoacetate, ethylene glycol diacetate, propylene carbonate, ethyl acetate, 2- (methoxymethoxy) ethanol, butyl cellulose Agent, ethylene glycol monoisoamyl ether, ethylene glycol monohexyl ether, 2- (hexyloxy) ethanol, sugar alcohol, diethylene glycol, propylene glycol, 1- (butoxyethoxy) propanol, Propylene glycol monomethyl ether acetate, dipropylene glycol, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, tripropylene glycol monomethyl ether, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether Ether acetate, ethylene glycol monobutyl ether acetate, ethylene glycol monoacetate, ethylene glycol diacetate, diethylene glycol monoethyl ether acetate, propylene glycol diacetate, Diisopentyl ether, diethylene glycol monobutyl ether acetate, 2- (2-ethoxyethoxy) ethyl acetate, diethylene glycol acetate, triethylene glycol, triethylene glycol Ethylene glycol monomethyl ether, triethylene glycol monoethyl ether, methyl lactate, ethyl lactate, methyl acetate, ethyl acetate Ethyl acetate, n-butyl acetate, propylene glycol monoethyl ether, methyl pyruvate, ethyl pyruvate, methyl 3-methoxypropionate, methyl ethyl 3-ethoxypropionate, 3 -Ethyl methoxypropionate, 3-ethoxypropionic acid, 3-methoxypropionic acid, propyl 3-methoxypropionate, butyl 3-methoxypropionate, methyl lactate , Ethyl lactate, n-propyl lactate, n-butyl lactate, isoamyl lactate, diisobutyl ketone, ethyl carbitol, and the like.
As the lean solvent, a solvent represented by the following formula may be used.

R ₂₄ and R ₂₅ are each independently a linear or branched alkyl group having 1 to 8 carbon atoms. However, R ₂₄ + R ₂₅ is an integer greater than 3.
In addition, as the poor solvent, when the polyimide precursor and the polyimide contained in the liquid crystal alignment agent have high solubility to the solvent, the following [D-1] to formula [D- 3] Solvent shown.

In formula [D-1], D ¹ represents an alkyl group having 1 to 3 carbon atoms, in formula [D-2], D ² represents an alkyl group having 1 to 3 carbon atoms, and in formula [D-3], D ³ Represents an alkyl group having 1 to 4 carbon atoms.

The liquid crystal alignment agent of the present invention may include a crosslinkable compound having an epoxy group, an isocyanate group, a propylene oxide group, or a cyclic carbonate group, and a compound selected from a hydroxyl group, a hydroxyalkyl group, and a lower alkoxyalkyl group. A group of crosslinkable compounds having at least one substituent, or a crosslinkable compound having a polymerizable unsaturated bond.

Such a crosslinkable compound can use various well-known compounds according to the purpose.
Examples of the crosslinkable compound having an epoxy group include bisphenol acetone epoxy propyl ether, phenol novolac epoxy resin, cresol novolac epoxy resin, triglycidyl isotricyanate, Tetraglycidylamino diphenylene, tetraglycidyl-m-diamine, tetraglycidyl-1,3-bis (aminoethyl) cyclohexane, tetraphenylepoxy Propyl ether ethane, triphenylepoxypropyl ether ethane, bisphenol hexafluoroacetamidine diepoxypropyl ether, 1,3-bis (1- (2,3-epoxypropoxy) -1-trifluoromethyl-2,2,2-trifluoromethyl) benzene, 4,4-bis (2,3-epoxypropoxy) octafluorobiphenyl, triglycidyl-p -Aminophenol, tetraglycidyl-m-xylylenediamine, 2- (4- (2,3-epoxypropoxy) phenyl) -2- (4- (1,1-bis (4 -(2,3-epoxypropoxy) phenyl) ethyl) phenyl) propane or 1,3-bis (4- (1- (4- (2,3-epoxypropoxy) Phenyl) -1- (4- (1- (4- (2,3-epoxypropoxy) phenyl) -1-methylethyl) phenyl) ethyl) phenoxy) -2 -Propanol and the like.
Specific examples of the cross-linkable compound having a propylene oxide group include the formulas [4a] to [4k] described in International Publication No. WO2011 / 132751 (2011.10.27) on pages 58 to 59. Crosslinkable compound.
Specific examples of the crosslinkable compound having a cyclic carbonate group include formulas [5-1] to [5-42] described in International Publication No. WO2012 / 014898 (2012.2.2 publication), pages 76 to 82. The crosslinkable compound shown.
Specific examples of the crosslinkable compound having at least one kind of substituent selected from the group consisting of a hydroxyl group and an alkoxy group include those described in pages 62 to 66 of International Publication WO2011 / 132751 (2011.10.27 publication). Crosslinkable compounds of formula [6-1] to formula [6-48].
Among the above-mentioned crosslinkable compounds, particularly preferred users are the following compounds.

The content of the crosslinkable compound is preferably 0.1 to 150 parts by mass relative to 100 parts by mass of the entire polymer component. Among them, in order to allow the crosslinking reaction to proceed and exhibit the desired effect, it is preferably from 0.1 to 100 parts by mass, and more preferably from 1 to 50 parts by mass.

The liquid crystal alignment agent of the present invention may contain a compound that can improve the film thickness uniformity or surface smoothness of the liquid crystal alignment film when the liquid crystal alignment agent is applied.

Examples of the compound for improving the uniformity or surface smoothness of the liquid crystal alignment film include fluorine-based surfactants, polysiloxane-based surfactants, and non-ionic surfactants.
The amount of the surfactant used is preferably 0.01 to 2 parts by mass, and more preferably 0.01 to 1 part by mass with respect to 100 parts by mass of the entire polymer component contained in the liquid crystal alignment agent.

<Liquid crystal alignment film, liquid crystal display element>
The liquid crystal alignment film of the present invention is a film obtained by coating the above-mentioned liquid crystal alignment agent on a substrate and drying and firing. The substrate to which the liquid crystal alignment agent of the present invention is applied is not particularly limited as long as it is a highly transparent substrate, and a plastic substrate such as a glass substrate, a silicon nitride substrate, and an acrylic substrate or a polycarbonate substrate can be used. In this case, it is preferable to use a substrate on which an ITO electrode or the like for liquid crystal driving has been formed, from the viewpoint of simplifying the manufacturing process. In addition, in a reflective liquid crystal display element, if it is only a single-sided substrate, an opaque object such as a silicon wafer can also be used. At this time, the electrode can also use a material that reflects light such as aluminum.

The coating method of the liquid crystal alignment agent is generally implemented in the industry by screen printing, lithography, flexographic printing, or inkjet. Examples of other coating methods include a dipping method, a roll coating method, a slit coating method, a spin coating method, and a spray method.

After the liquid crystal alignment agent is coated on the substrate, the liquid crystal alignment film can be formed by evaporating the solvent by heating means such as a hot plate, a thermal cycle type oven, or an IR (infrared) type oven. The steps of drying and firing after applying the liquid crystal alignment agent of the present invention can be selected at any temperature and time. In general, in order to sufficiently remove the solvent contained, conditions such as drying at 50 to 120 ° C for 1 to 10 minutes, and then calcining at 150 to 300 ° C for 5 to 120 minutes can be mentioned. When the thickness of the sintered liquid crystal alignment film is too thin, the reliability of the liquid crystal display element may be reduced. Therefore, the thickness is preferably 5 to 300 nm, and more preferably 10 to 200 nm.

The liquid crystal alignment agent of the present invention is applied to a substrate and fired, and then subjected to alignment treatment by rubbing treatment or photo alignment treatment. In addition, alignment treatment is not performed for vertical alignment applications and the like, and can be used as a liquid crystal alignment film. For the alignment treatment such as the rubbing treatment or the photo-alignment treatment, a known method or device can be used.
As an example of a method for manufacturing a liquid crystal cell, a liquid crystal display element having a passive array structure is used as an example for description. Furthermore, it may be a liquid crystal display element having an active array structure in which a switching element such as a TFT (Thin Film Transistor) is provided in each pixel portion constituting the image display.

Specifically, a transparent glass substrate is prepared, a common electrode is provided on one substrate, and a segment electrode is provided on the other substrate. These electrodes can be made of, for example, ITO electrodes, and can be displayed in a desired image by patterning. Next, an insulating film is provided on each substrate so as to cover the common electrode and the segment electrode. The insulating film can be made of, for example, a film of SiO ₂ -TiO ₂ formed by a sol-gel method.

Next, a liquid crystal alignment film is formed on each substrate, and one substrate and the other substrate are overlapped so that the liquid crystal alignment film surfaces face each other, and the periphery is adhered with a sealant. In order to control the substrate gap, a spacer is usually mixed in the sealant in advance, and it is also preferable to disperse the spacer for controlling the substrate gap in advance in the portion where the sealant is not provided. A part of the sealant is provided with an opening capable of filling liquid crystal from the outside in advance. Next, a liquid crystal material is injected into a space surrounded by the two substrates and the sealant through an opening provided in the sealant, and then the opening is sealed with an adhesive. As the injection system, a vacuum injection method can be used, and a method using a capillary phenomenon in the atmosphere can also be used. The liquid crystal material may be any of a positive type liquid crystal material and a negative type liquid crystal material, but a negative type liquid crystal material is preferred. Next, set the polarizer. Specifically, a pair of polarizing plates are affixed on the surface opposite to the liquid crystal layer of two substrates.

[Example]

The following examples are given to explain the present invention more specifically, but the present invention is not limited by these. The abbreviations of the following compounds and the measurement methods of each characteristic are as follows.

＜ Tetracarboxylic dianhydride ＞
CBDA: 1,2,3,4, -cyclobutane tetracarboxylic dianhydride
BODA: Bicyclic [3,3,0] octane-2,4,6,8-tetracarboxylic dianhydride
DSDA: 3,3 ', 4,4'-diphenylphosphonium tetracarboxylic dianhydride
PMDA: pyromellitic anhydride

＜ Diamine ＞
DA-1: p-phenylenediamine
DA-2: 4,4-Diaminodiphenylmethane
DA-3: 3,5-diaminobenzoic acid
DA-4: 3,5-diamino-N- (pyridin-3-ylmethyl) benzidine
DA-5: 4,4 '-[isopropylidenebis (p-phenyleneoxy)] diphenylamine
DA-6: Diamine of the following formula DA-6
DA-7: 1- (4- (2- (2,4-diaminophenoxy) ethoxy) phenyl) -2-hydroxy-2-methylacetone
DA-8: 1,3-diamino-4- [4- (trans-4-n-heptylcyclohexyl) phenoxy] benzene
DA-9: 1,3-diamino-4- [trans-4- [trans-4- (pentylcyclohexyl) -cyclohexyl] phenoxy] benzene

＜ Structure of DA-1 ~ DA-9 ＞

＜ Additives ＞
TM-BIP-A: 2,2'-bis (4-hydroxy-3,5-dihydroxymethylphenyl) propane

＜ Organic solvents ＞
NMP: 1-methyl-2-pyrrolidone
NEP: 1-ethyl-2-pyrrolidone
GBL: γ-butyrolactone
BCS: Butyl Cellosolve
PB: 1-butoxy-2-propanol
DME: Dipropylene glycol dimethyl ether
DIBK: Diisobutyl ketone In the examples, the molecular weights and polyimide ratios of polyamidic acid and polyimide were evaluated by the following procedures.

＜ Molecular weight measurement ＞
The molecular weights of the polyamic acid and the polyimide were normal temperature gel permeation chromatography (GPC) apparatus (GPC-101) manufactured by Showa Denko Corporation, and column (KD-803, KD-805) manufactured by Shodex Corporation. The measurement conditions are shown below.
Column temperature: 50 ℃
Eluent: N, N'-dimethylformamide (additives: 30 mmol / L of lithium bromide-hydrate (LiBr · H2O), 30 mmol / L of phosphoric acid / anhydrous crystal (o-phosphoric acid), tetrahydrofuran (THF) (10ml / L)
Flow rate: 1.0ml / div. Standard sample for standard line preparation: TSK standard polyethylene oxide (molecular weight about 900,000, 150,000, 100,000, 30,000) manufactured by Tosoh Corporation, and polyethylene glycol manufactured by Polymer Labs (Molecular weight is about 12,000, 4,000, 1,000).

＜ Measurement of sulfonium imidization rate ＞
Put 20 mg of polyfluorene imine powder into an NMR sample tube (manufactured by Kusano Science Corporation, NMR sampling tube standard φ5), and add deuterated dimethylsulfine (DMSO-d6, 0.05% TMS (tetramethylsilane) mixed product) 0.53ml, apply ultrasound to completely dissolve. A 500 MHz proton NMR was measured on this solution using an NMR measuring instrument (JNW-ECA500) manufactured by Japan Electronic Materials Corporation.醯 The imidization rate is determined from the protons derived from the structure that has not changed before and after the imidization, and the peak proton value of this proton is used, and it is derived from the 出现 that appears near 9.0 ppm to 11.0 ppm. The cumulative proton peak value of the NH group of the amino acid is obtained by the following formula (1).

醯 Imination ratio (%) = (1-α ・ x / y) × 100 ・ ・ ・ (1)

In the above formula (1), x is a cumulative value of a proton peak derived from an NH group of amidine, y is a cumulative peak value of a reference proton, and α is a polyamidate (amidation ratio is 0%) In this case, the ratio of the number of the reference proton to one of the amino acid NH matrix protons.

<Synthesis example 1>
BODA (22.27 g, 89 mmol), DA-7 (14.70 g, 44.5 mmol), DA-4 (12.94 g, 53.4 mmol), DA-9 (19.34 g, 44.5 mmol), DA-8 (13.55 g, 35.6 mmol) was mixed in NMP (331.2 g) and reacted at 60 ° C for 3 hours. Then, CBDA (16.93 g, 86.3 mmol) and NMP (67.2 g) were added and reacted at 40 ° C for 15 hours to obtain a polymer. Amino acid solution (a). The number average molecular weight of this polyamic acid solution (a) was 22,000, and the weight average molecular weight was 58,000. After adding NMP to this polyamic acid solution (a) (498.13g) to dilute the content of the polyamic acid solution (a) to 10% by mass, anhydrous acetic acid (90.87g) was added as the fluorinated catalyst And pyridine (28.16g), reacted at 70 ° C for 3.5 hours. This reaction solution was poured into methanol (5,000 ml), and the obtained precipitate was separated by filtration. This deposit was wash | cleaned with methanol, and it dried under reduced pressure at 100 degreeC, and obtained polyfluorene imine (A). The polyimide (A) has an imidization ratio of 72%.

<Synthesis example 2>
BODA (23.02 g, 92 mmol), DA-3 (14.0 g, 92 mmol), DA-5 (22.66 g, 55.2 mmol), DA-8 (14.01 g, 36.8 mmol) were mixed in NMP (294.73 g), After reacting at 60 ° C for 1 hour, CBDA (6.68g, 34.0mmol) and NMP (26.7g) were added. After reacting at 20 ° C for 1 hour, DSDA (19.78g, 55.2mmol) and NMP (79.11g) were added. After reacting at 40 ° C for 2 hours, a polyamic acid solution (b) was obtained. The number average molecular weight of this polyamic acid solution (b) was 17,000, and the weight average molecular weight was 45,000. NMP was added to this polyamic acid solution (b) (500.69g) to dilute the content of the polyamino acid solution (b) to 6.5% by mass, and then anhydrous acetic acid (93.93g) was added as a phosphonium imidization catalyst. And pyridine (72.77 g), reacted at 75 ° C for 3.5 hours. This reaction solution was poured into methanol (5,000 ml), and the obtained precipitate was separated by filtration. This deposit was wash | cleaned with methanol, and it dried under reduced pressure at 100 degreeC, and obtained polyfluorene imine (B). The polyimide (B) has a hydrazone imidization rate of 74%.

<Synthesis example 3>
BODA (25.02 g, 100 mmol), DA-1 (8.65 g, 80 mmol), DA-6 (6.83 g, 20 mmol), and DA-8 (38.6 g, 100 mmol) were mixed in NMP (214.2 g) at 60 After reacting at 3 ° C for 3 hours, CBDA (19.61 g, 100 mmol) and NMP (178.5 g) were added and reacted at 40 ° C for 15 hours to obtain a polyamic acid solution (c). The number average molecular weight of this polyamic acid solution (c) was 23,000, and the weight average molecular weight was 60,000. NMP was added to this polyamic acid solution (c) (450.0 g) to dilute the content of the polyamino acid solution (a) to 10% by mass, and then anhydrous acetic acid (103.6 g) was added as a phosphonium imidization catalyst. And pyridine (32.11g), reacted at 70 ° C for 3.5 hours. This reaction solution was poured into methanol (3,600 ml), and the obtained precipitate was separated by filtration. This deposit was wash | cleaned with methanol, and it dried under reduced pressure at 100 degreeC, and obtained polyimide (C). The polyimide (C) has an imidization rate of 69%.

<Synthesis example 4>
BODA (25.02 g, 100 mmol), DA-7 (6.60 g, 20 mmol), DA-2 (23.79 g, 120 mmol), and DA-9 (26.1 g, 60 mmol) were mixed in NMP (225.9 g) at 60 After reacting at 3 ° C for 3 hours, CBDA (19.61 g, 100 mmol) and NMP (178.5 g) were added, and the mixture was reacted at 40 ° C for 15 hours to obtain a polyamic acid solution (d). The polyamine solution (d) had a number average molecular weight of 24,000 and a weight average molecular weight of 62,000. After adding NMP to this polyamic acid solution (d) (450.0 g) to dilute the content of the poly (amino acid) solution (d) to 10% by mass, anhydrous acetic acid (90.9 g) was added as a fluorinated catalyst. And pyridine (28.17 g), reacted at 70 ° C for 3.5 hours. This reaction solution was poured into methanol (3,600 ml), and the obtained precipitate was separated by filtration. This deposit was wash | cleaned with methanol, and it dried under reduced pressure at 100 degreeC, and obtained polyimide (D). The polyimide (D) has a hydrazone imidization rate of 73%.

<Synthesis example 5>
BODA (25.02g, 100mmol), DA-3 (12.17g, 80mmol), DA-4 (14.53g, 60mmol), DA-8 (22.83g, 60mmol) were mixed in NMP (198.17g) at 60 After reacting at 3 ° C for 3 hours, PMDA (8.72 g. 40 mmol) and NMP (34.9 g) were added, and the reaction was carried out at 40 ° C for 3 hours. Finally, CBDA (11.76 g, 60 mmol) and NMP (147.15 g) were added and reacted for 15 hours to obtain a polyamic acid solution (e). The number average molecular weight of this polyamic acid solution (e) was 25,000, and the weight average molecular weight was 65,000. After adding NMP to this polyamic acid solution (e) (450.0 g) to dilute the content of the polyamic acid solution (d) to 10% by mass, anhydrous acetic acid (96.7 g) was added as a fluorinated catalyst. And pyridine (29.97 g), reacted at 70 ° C for 3.5 hours. This reaction solution was poured into methanol (3,600 ml), and the obtained precipitate was separated by filtration. This deposit was wash | cleaned with methanol, and it dried under reduced pressure at 100 degreeC, and obtained polyimide (E). The polyimide (E) has an imidization ratio of 72%.

<Example 1>
NEP (198 g) was added to the polyimide (A) (13.5 g) obtained in Synthesis Example 1 and the polyimide (B) (13.5 g) obtained in Synthesis Example 2, and the mixture was stirred at 70 ° C for 20 hours to make Its dissolved. To this solution, NEP (17.91 g), GBL (151.2 g), PB (180 g), DME (144 g), TM-BIP-A (1.89 g) were added and stirred at 25 ° C for 2 hours. The solution was filtered using a filter with a pore size of 1 μm to prepare the liquid crystal alignment agent of the present invention [A]

<Example 2>
NMP (150.73 g) was added to the polyimide (A) (13.3 g) obtained in Synthesis Example 1 and the polyimide (B) (13.3 g) obtained in Synthesis Example 2 and stirred at 70 ° C. for 20 hours. Its dissolved. NMP (65.30 g), GBL (115.02 g), BCS (251.6 g), DME (107.8 g), TM-BIP-A (1.86 g) were added to the solution, and the mixture was stirred at 25 ° C for 2 hours. The solution was filtered using a filter having a pore size of 1 μm to prepare the liquid crystal alignment agent [B] of the present invention.

<Example 3>
To the polyimide (C) (13.3 g) obtained in Synthesis Example 3 and the polyimide (E) (13.3 g) obtained in Synthesis Example 5, NMP (150.73 g) was added, and the mixture was stirred at 70 ° C for 20 hours. Its dissolved. To this solution, NMP (65.30 g), GBL (115.02 g), BCS (251.6 g), DME (107.8 g), TM-BIP-A (1.86 g) were added, and stirred at 25 ° C for 2 hours. The solution was filtered using a filter having a pore size of 1 μm to prepare the liquid crystal alignment agent [C] of the present invention.

<Example 4>
To the polyimide (D) (13.5 g) obtained in Synthesis Example 4 and the polyimide (E) (13.5 g) obtained in Synthesis Example 5, NEP (198 g) was added and stirred at 70 ° C for 20 hours to dissolve. . To this solution, NEP (17.91 g), GBL (151.2 g), PB (180 g), DME (144 g), TM-BIP-A (1.86 g) were added and stirred at 25 ° C for 2 hours. The solution was filtered using a filter having a pore size of 1 μm to prepare the liquid crystal alignment agent [D] of the present invention.

<Example 5>
To the polyimide (A) (13.3 g) obtained in Synthesis Example 1 and the polyimide (E) (13.3 g) obtained in Synthesis Example 5, NEP (150.73 g) was added, and the mixture was stirred at 70 ° C for 20 hours to make Its dissolved. To this solution, NEP (65.30 g), GBL (115.02 g), BCS (251.6 g), DME (107.8 g), TM-BIP-A (1.86 g) were added and stirred at 25 ° C for 2 hours. The solution was filtered using a filter having a pore size of 1 μm to prepare the liquid crystal alignment agent [E] of the present invention.

〈Comparative example 1〉
To the polyimide (A) (13.5 g) obtained in Synthesis Example 1 and the polyimide (B) (13.5 g) obtained in Synthesis Example 2, NEP (198 g) was added, and the mixture was stirred at 70 ° C for 20 hours to make them Dissolve. To this solution, NEP (169.11 g), PB (216 g), DME (108 g), TM-BIP-A (1.89 g) was added and stirred at 25 ° C for 2 hours. This solution was filtered using a filter having a pore size of 1 μm to prepare a liquid crystal alignment agent [F].

〈Comparative example 2〉
To the polyimide (A) (10.13 g) obtained in Synthesis Example 1 and the polyimide (B) (10.13 g) obtained in Synthesis Example 2, NEP (148.59 g) was added, and the mixture was stirred at 70 ° C for 20 hours to make Its dissolved. To this solution, NEP (261.67 g), PB (287.95 g), and TM-BIP-A (1.42 g) were added and stirred at 25 ° C for 2 hours. This solution was filtered using a filter having a pore size of 1 μm to prepare a liquid crystal alignment agent [G].

〈Comparative example 3〉
To the polyimide (A) (13.3 g) obtained in Synthesis Example 1 and the polyimide (B) (13.3 g) obtained in Synthesis Example 2, NEP (195.07 g) was added, and the mixture was stirred at 70 ° C for 20 hours to make Its dissolved. To this solution, NEP (202.08 g), PB (212.79 g), DIBK (70.93 g), TM-BIP-A (1.86 g) were added and stirred at 25 ° C for 2 hours. This solution was filtered using a filter having a pore size of 1 μm to prepare a liquid crystal alignment agent [H].

[Method of Forming and Evaluating Coating Film]
The prepared liquid crystal alignment agent is applied on a substrate by an inkjet method, and preliminary drying and main firing are performed to form a coating film. The evaluation of inkjet coating was performed using an inkjet device (type IJ-1021) manufactured by Shibaura Advanced Technology Co., Ltd. under the following conditions.
Inkjet coating conditions:
Print head: H18, H1A
Nozzle No./Head=256
Nozzle nozzle distance: 396.88um
Head offset: 198.43um
Scans: 2 Scan
Low spacing of nozzle arrangement direction (X): 99.22um
Platform speed: 512mm / sec, frequency: 4000Hz
Drop Pitch (Y): 128um
Coating pattern setting value: 80mm × 80mm
Film thickness: 1000Å.
Substrate: The evaluation of the halo area is a 100 × 100mm glass substrate with Cr or ITO electrodes fully attached on one side. The evaluation of the unevenness (C / H unevenness) around the contact hole uses a TFT substrate.
Setting time from the end of coating to pre-drying: 45 seconds Pre-drying: A substrate was set on a needle having a height of 1 mm on a hot plate set to 90 ° C. and dried for 40 seconds.
Hon-yaki: 230 ° C / 20 minutes (IR oven)

<Evaluation method of halo area>
The evaluation of the halo region at the tip of the liquid crystal alignment film was performed by using a light microscope (ECLIPSE L300N manufactured by Nikon Corporation) to observe the change in the color tone (film thickness) of the tip of the coating film above, below, left, and right relative to the coating direction Uneven). Specifically, an optical microscope was used to observe the magnification at 2.5 times, and the length of the color change (film thickness unevenness) of the obtained coating film image was measured. All paint film images were obtained at the same magnification. The average value of the hue change (uneven film thickness) of the end of the coating film at the top, bottom, left, and right is 7mm or more, and the one with 6mm to 5mm is △, and the one with less than 5mm Rated 〇.

＜ Evaluation method of C / H unevenness ＞
The inside of the coating film obtained above was observed with an optical microscope at a magnification of 5 times. The number of C / H around the C / H unevenness in the field of view was 20% or less. The above are rated as "×".

The evaluation results of the liquid crystal alignment agents obtained in Examples 1 to 5 and Comparative Examples 1 to 3 are shown in the following tables.

[Industrial availability]

The liquid crystal alignment agent of the present invention can solve the display unevenness near the frame by improving the adhesion between the sealant and the liquid crystal alignment film in a narrow frame liquid crystal display element capable of ensuring a large number of display surfaces, which is extremely useful in industry. By.

Claims (14)

A liquid crystal alignment agent characterized by containing a polymer and an organic solvent, The above polymer is at least one polyimide precursor selected from the reactant of a tetracarboxylic acid derivative and a diamine and a polyimide of the imine, The organic solvent contains Component A: at least one selected from γ-butyrolactone and γ-valerolactone, Component B: at least one selected from the group consisting of dipropylene glycol dimethyl ether and diacetone alcohol; The content of the A component and the B component is 25% by weight or less, and the difference between the content of the A component and the B component is 5% by weight or less. For example, the liquid crystal alignment agent of claim 1, which further contains a component C: selected from the group consisting of N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, and N-butyl-2-pyrrolidone At least one type, and the weight of the C component relative to the entire liquid crystal alignment agent is 40% by weight or less. The liquid crystal alignment agent according to claim 1, wherein the polymer contains a side chain structure of the following formula [1-1]; In Formula [1-1], Y ¹ and Y ³ are each independently selected from the group consisting of a single bond,-(CH ₂ ) _a- (a is an integer of 1 to 15), -O-, -CH ₂ O-,- At least one of the groups formed by COO- and -OCO-, Y ² represents a single bond or-(CH ₂ ) _b- (b is an integer from 1 to 15); however, Y ¹ or Y ³ is a single bond,-( When CH ₂ ) _a- , Y ² is a single bond; Y ¹ is at least one selected from the group consisting of -O-, -CH ₂ O-, -COO-, and -OCO-, and / or Y ³ is When at least one member is selected from the group consisting of -O-, -CH ₂ O-, -COO-, and -OCO-, Y ² is a single bond or-(CH ₂ ) _b- ; Y ⁴ represents a member selected from benzene rings, At least one kind of divalent cyclic group formed by a cyclohexane ring and a heterocyclic ring, or a divalent organic group having 17 to 51 carbon atoms having a steroid skeleton, and any hydrogen atom on the aforementioned cyclic group may be carbon Substituted by alkyl groups of 1 to 3, alkoxy groups of 1 to 3 carbons, fluorine-containing alkyl groups of 1 to 3 carbon atoms, fluorine-containing alkoxy groups of 1 to 3 carbon atoms or fluorine atoms; Y ⁵ represents optional At least one kind of cyclic group formed by a free benzene ring, a cyclohexane ring, and a heterocyclic ring. Any hydrogen atom on these cyclic groups can be an alkyl group having 1 to 3 carbon atoms, and 1 to 3 carbon atoms. Alkoxy, fluorinated alkyl with 1 to 3 carbons, fluorinated alkoxy with 1 to 3 carbons or fluorine Substituted by an atom; Y ⁶ represents a group selected from the group consisting of an alkyl group having 1 to 18 carbon atoms, an alkenyl group having 2 to 18 carbon atoms, a fluorine-containing alkyl group having 1 to 18 carbon atoms, an alkoxy group having 1 to 18 carbon atoms, and carbon number At least one of the groups of 1 to 18 fluorine-containing alkoxy groups; n represents an integer of 0 to 4. The liquid crystal alignment agent according to claim 2, wherein the polymer contains a side chain structure of the following formula [1-1]; In Formula [1-1], Y ¹ and Y ³ are each independently selected from the group consisting of a single bond,-(CH ₂ ) _a- (a is an integer of 1 to 15), -O-, -CH ₂ O-,- At least one of the groups formed by COO- and -OCO-; Y ² represents a single bond or-(CH ₂ ) _b- (b is an integer from 1 to 15); however, Y ¹ or Y ³ is a single bond,-( When CH ₂ ) _a- , Y ² is a single bond; Y ¹ is at least one selected from the group consisting of -O-, -CH ₂ O-, -COO-, and -OCO-, and / or Y ³ is When at least one member is selected from the group consisting of -O-, -CH ₂ O-, -COO-, and -OCO-, Y ² is a single bond or-(CH ₂ ) _b- ; Y ⁴ represents a member selected from benzene rings, At least one kind of divalent cyclic group formed by a cyclohexane ring and a heterocyclic ring, or a divalent organic group having 17 to 51 carbon atoms having a steroid skeleton, and any hydrogen atom on the aforementioned cyclic group may be carbon Substituted by alkyl groups of 1 to 3, alkoxy groups of 1 to 3 carbons, fluorine-containing alkyl groups of 1 to 3 carbon atoms, fluorine-containing alkoxy groups of 1 to 3 carbon atoms or fluorine atoms; Y ⁵ represents optional At least one kind of cyclic group formed by a free benzene ring, a cyclohexane ring and a heterocyclic ring. Any hydrogen atom on these cyclic groups can be an alkyl group having 1 to 3 carbon atoms, and an alkyl group having 1 to 3 carbon atoms. Alkoxy, fluorinated alkyl with 1 to 3 carbons, fluorinated alkoxy with 1 to 3 carbons or fluorine Substituted by an atom; Y ⁶ represents a group selected from the group consisting of an alkyl group having 1 to 18 carbon atoms, an alkenyl group having 2 to 18 carbon atoms, a fluorine-containing alkyl group having 1 to 18 carbon atoms, an alkoxy group having 1 to 18 carbon atoms, and carbon number At least one of the groups of 1 to 18 fluorine-containing alkoxy groups; n represents an integer of 0 to 4. The liquid crystal alignment agent according to claim 1, wherein the tetracarboxylic dianhydride component contains a tetracarboxylic dianhydride represented by the following formula [3]; In Formula [3], X ₁ is a tetravalent organic group having 4 to 13 carbon atoms, and contains a non-aromatic cyclic hydrocarbon group having 4 to 10 carbon atoms. The liquid crystal alignment agent according to claim 2, wherein the tetracarboxylic dianhydride component contains a tetracarboxylic dianhydride represented by the following formula [3]; In Formula [3], X ₁ is a tetravalent organic group having 4 to 13 carbon atoms, and contains a non-aromatic cyclic hydrocarbon group having 4 to 10 carbon atoms. The liquid crystal alignment agent according to claim 3, wherein the tetracarboxylic dianhydride component contains a tetracarboxylic dianhydride represented by the following formula [3]; In Formula [3], X ₁ is a tetravalent organic group having 4 to 13 carbon atoms, and contains a non-aromatic cyclic hydrocarbon group having 4 to 10 carbon atoms. The liquid crystal alignment agent according to claim 4, wherein the tetracarboxylic dianhydride component contains a tetracarboxylic dianhydride represented by the following formula [3]; In Formula [3], X ₁ is a tetravalent organic group having 4 to 13 carbon atoms, and contains a non-aromatic cyclic hydrocarbon group having 4 to 10 carbon atoms. The liquid crystal alignment agent according to claim 5, wherein X ₁ is a structure represented by the following formula; R ₃ to R ₆ , R ₂₄ and R ₂₅ are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkynyl group having 2 to 6 carbon atoms, containing fluorine A monovalent organic group having 1 to 6 carbon atoms, or a phenyl group. The liquid crystal alignment agent according to claim 6, wherein X _{1 has} a structure represented by the following formula; R ₃ to R ₆ , R ₂₄ and R ₂₅ are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkynyl group having 2 to 6 carbon atoms, containing fluorine A monovalent organic group having 1 to 6 carbon atoms, or a phenyl group. The liquid crystal alignment agent according to claim 7, wherein X _{1 has} a structure represented by the following formula; R ₃ to R ₆ , R ₂₄ and R ₂₅ are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkynyl group having 2 to 6 carbon atoms, containing fluorine A monovalent organic group having 1 to 6 carbon atoms, or a phenyl group. The liquid crystal alignment agent according to claim 8, wherein X _{1 has} a structure represented by the following formula; R ₃ to R ₆ , R ₂₄ and R ₂₅ are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkynyl group having 2 to 6 carbon atoms, containing fluorine A monovalent organic group having 1 to 6 carbon atoms, or a phenyl group. A liquid crystal alignment film is obtained from the liquid crystal alignment agent according to any one of claim 1 to claim 12. A liquid crystal display element is provided with the liquid crystal alignment film as claimed in claim 13.