TW201940538A - Liquid crystal aligning agent, polymer for obtaining same, liquid crystal alignment film, and liquid crystal display element using same - Google Patents

Abstract

A liquid crystal aligning agent that contains a polymer which has a structure represented by formula (1), and which is composed of a polyurea and a polyurea copolymer. In formula (1), X represents a divalent organic group derived from a diisocyanate derivative; Y represents a divalent organic group derived from a diamine derivative; R1 represents an optionally branched alkyl group having 1-4 carbon atoms; R2 represents a hydrogen atom, an aliphatic hydrocarbon group having 1-4 carbon atoms, or an organic group represented by formula (1-1); and each of Ra and Rb independently represents a hydrogen atom or an aliphatic hydrocarbon group having 1-2 carbon atoms. In formula (1-1), a black dot represents the bonding position to a nitrogen atom; and R1, Ra and Rb are as defined above.

Description

Liquid crystal alignment agent, polymer for obtaining the liquid crystal alignment agent, liquid crystal alignment film, and liquid crystal display element using the liquid crystal alignment film

The present invention relates to a liquid crystal alignment agent, a polymer for obtaining the liquid crystal alignment agent, a liquid crystal alignment film, and a liquid crystal display element using the liquid crystal alignment film.

In the liquid crystal display element, the function of the liquid crystal alignment film is to align the liquid crystals in a certain direction. At present, the main liquid crystal alignment film used in industry is a polyimide-based system consisting of polyimide (also known as polyimide precursor, polyimide), and polyimide solution. The liquid crystal alignment agent is coated on a substrate and calcined to form a film. In addition, when the liquid crystal is aligned in parallel or obliquely with respect to the substrate surface, a surface stretching treatment (abrasion treatment) is performed by friction after film formation. As a method for replacing the rubbing treatment, a method using anisotropic photochemical reactions such as irradiation with polarized ultraviolet rays has also been proposed.

In order to make the display characteristics of liquid crystal display elements better, many technologies have been proposed. For example, Patent Document 1 (Japanese Patent Application Laid-Open No. 2-287324) proposes to use a polyimide resin having a specific repeating structure in order to obtain a high voltage holding ratio (VHR). In addition, in Patent Document 2 (Japanese Patent Application Laid-Open No. 10-104633), in order to shorten the time until the afterimage disappears, it is proposed to use a soluble polyfluorene imine having a nitrogen atom in addition to the fluorene imino group.
[Previous Technical Literature]
[Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2-287324 [Patent Document 2] Japanese Patent Laid-Open No. 10-104633

[Inventive Problems]

In recent years, with the multifunctionalization and diversification of liquid crystal displays (LCD panels), from the development of displays using glass substrates, the flexible displays using resin substrates (plastic substrates, that is, film substrates) have also been actively developed. Therefore, there is a need for a liquid crystal alignment film that can be obtained by low-temperature calcination. In addition, the reliability (high voltage retention rate, etc.) required for the liquid crystal alignment film is also required.

Examples of the material used for the liquid crystal alignment film include polyimide precursors such as polyamic acid and polyamic acid esters, and polyimide obtained by dehydration by calcination or chemical reaction. Among them, polyamic acid is easy to synthesize and has excellent solubility in a solvent, so a liquid crystal alignment agent having excellent coatability and film-forming property to a substrate can be obtained. However, since polyamic acid is easily decomposed by hydrolysis or the like due to its structure, it is difficult to ensure reliability for a long period of time by using the liquid crystal alignment film obtained therefrom.

On the other hand, soluble polyimide (solvent-soluble polyimide obtained by the dehydration reaction of polyamic acid), because it has been preliminarily imidized, does not require heating to make it imidized. Step, so it can be calcined at a relatively low temperature. In addition, since it has excellent chemical stability and heat resistance, a liquid crystal alignment film obtained by using soluble polyfluorene imide is easy to ensure reliability for a long period of time. However, there are few solvents that can dissolve the soluble polyfluorene imide, so the solvents that can be used are limited. As a result, when the soluble polyfluorene imide is used, precipitation is easy to occur during coating and film formation, and the coating film is easy to use. There is a defect. In recent years, with the enlargement, high definition, and diversification of the use environment of LCD panels, in order to solve their respective problems, it is necessary to explore methods that can improve various characteristics.

The present invention has been made in view of the foregoing circumstances, and an object thereof is to provide a liquid crystal alignment agent that can be calcined at a low temperature and has good printability (solubility of an obtained polymer in an organic solvent). In addition, a polymer that can obtain the liquid crystal alignment agent is provided. In addition, the present invention provides a liquid crystal alignment film that is excellent in abrasion resistance when performing a rubbing treatment, has good liquid crystal alignment (that is, can achieve a low pretilt angle), and has a high voltage holding ratio. A liquid crystal display element is provided with the liquid crystal alignment film.
[Methods for solving problems]

The inventor of this case worked hard and found that a polymer with a specific structure and a liquid crystal alignment agent using the polymer are effective for achieving the above-mentioned purpose, and completed the present invention. The above-mentioned polymers are novel, and monomers for obtaining the above-mentioned polymers also include novel compounds.

That is, the gist of the present invention is the following 1. to 9.
1. A liquid crystal alignment agent comprising a polymer of a polyurea and a polyurea copolymer having a structure represented by the following formula (1);

[Chemical 1]
In the formula, X represents a divalent organic group derived from a diisocyanate derivative, and Y represents a divalent organic group derived from a diamine derivative; R ₁ represents an alkyl group having 1 to 4 carbon atoms, and may have branches; R ₂ Represents a hydrogen atom, an aliphatic hydrocarbon group having 1 to 4 carbon atoms, or an organic group represented by the following formula (1-1); Ra and Rb each independently represents a hydrogen atom or an aliphatic hydrocarbon group having 1 to 2 carbon atoms;

[Chemical 2]
Wherein the portion of black dots junction bond of a nitrogen atom, R _1, Ra and Rb above, and R _1, Ra and Rb have the same meaning.

2. The liquid crystal alignment agent according to 1., a polymer containing a polyurea and a polyurea copolymer obtained from a diamine derivative and a diisocyanate derivative represented by the following formula (2);

[Chemical 3]
In the formula, A represents a divalent organic group of an aliphatic hydrocarbon group or an aromatic hydrocarbon group, and B and C each independently represent a single bond or an aliphatic hydrocarbon group having 1 to 5 carbon atoms; R ₁ , R ₂ , Ra, and Rb and the above R ₁ , R ₂ , Ra and Rb have the same meaning.

3. The liquid crystal alignment agent according to 2., which comprises a polyurea and a polyurea copolymer obtained from a diamine compound and a diisocyanate derivative represented by the following formula (3) in the diamine derivative;

[Chemical 4]
In the formula, Ar represents an aryl group, and D represents a single bond or a hydrocarbon group having 1 to 5 carbon atoms; R ₁ , R ₂ , Ra, and Rb have the same meanings as the above-mentioned R ₁ , R ₂ , Ra, and Rb.

4. Liquid crystal alignment agent according to 3., a polymer containing a polyurea and a polyurea copolymer obtained from a diamine compound and a diisocyanate derivative represented by the following formula (3-a) in the diamine derivative ;

[Chemical 5]
In the formula, D and R _{1 have the} same meaning as those of D and R ₁ .

5. A polymer obtained from a diamine compound and a diisocyanate derivative represented by the following formula (3-1);

[Chemical 6]
In the formula, R ₁ represents an alkyl group having 1 to 4 carbon atoms and may be branched; B represents a single bond or an aliphatic hydrocarbon group having 1 to 5 carbon atoms; Ra and Rb each independently represent a hydrogen atom or 1 to 3 carbon atoms; 2 aliphatic hydrocarbon group.

6. The polymer according to 5., which is at least one of the diamine compound and the diisocyanate derivative represented by the following formulae (4-1) to (4-11) and formula (4-13) obtain;

[Chemical 7]

7. A liquid crystal alignment agent using a polymer such as 5. or 6.

8. A liquid crystal alignment film obtained from a liquid crystal alignment agent according to any one of 1. to 4. and 7.

9. A liquid crystal display element using the liquid crystal alignment film of 8.
[Effect of Invention]

According to the present invention, it is possible to provide a liquid crystal alignment agent that can be calcined at a low temperature, obtain a high-quality liquid crystal alignment film, and have excellent printability. Also, according to the present invention, a novel polymer for obtaining the above-mentioned liquid crystal alignment agent can be provided. In addition, according to the present invention, a liquid crystal alignment film having excellent friction resistance when performing a rubbing treatment, a low pretilt angle, and a high voltage retention ratio can be provided. According to the present invention, a liquid crystal display device using the liquid crystal alignment film can be provided.

A liquid crystal alignment agent according to an aspect of the present invention includes a polymer according to an aspect of the present invention, the polymer being a diamine derivative (hereinafter sometimes referred to as "diamine") represented by formula (2), and two An isocyanate derivative (hereinafter sometimes referred to as "diisocyanate") is obtained.

> Diamine used in the present invention>
The diamine used in the present invention is represented by formula (2).

[Chemical 8]
In the formula, A represents a divalent organic group of an aliphatic hydrocarbon group or an aromatic hydrocarbon group, and B and C each independently represent a single bond or an aliphatic hydrocarbon group having 1 to 5 carbon atoms. R ₁ represents an alkyl group having 1 to 4 carbon atoms, and may be branched. R ₂ represents a hydrogen atom, an aliphatic hydrocarbon group having 1 to 4 carbon atoms, or an organic group represented by formula (1-1). Ra and Rb each independently represent a hydrogen atom or an aliphatic hydrocarbon group having 1 to 2 carbon atoms.

Considering the viewpoints of the polymerization reactivity of the monomers, the ability to obtain a liquid crystal alignment film with excellent heat resistance and liquid crystal alignment, in formula (2), A is an aromatic hydrocarbon group, B is an aliphatic hydrocarbon group having 1 to 3 carbon atoms, and C is One-button is ideal. Formula (2) specifically includes the following structures.

[Chemical 9]
In the formula, Ar represents an aryl group, and D represents a single bond or a hydrocarbon group having 1 to 5 carbon atoms. R ₁ , R ₂ , Ra, and Rb have the same meanings as the aforementioned R ₁ , R ₂ , Ra, and Rb.

In consideration of the viewpoint that it is easy to obtain a reagent for synthesizing a diamine, good reactivity with a diisocyanate, and good physical properties of the obtained polymer, in formula (3), Ar is preferably a phenyl group, and R _{2 is} preferably A hydrogen atom is preferred. Therefore, the formula (3) is preferably a structure represented by the following formula (3-a) '. Among them, in formula (3), it is preferred that Ra and Rb are each a hydrogen atom. Therefore, the formula (3) is particularly preferably represented by the formula (3-a).

[Chemical 10]
In the formula, D and R _{1 have the} same meaning as those of D and R ₁ .

In consideration of the viewpoint that the objective monomer can be obtained ideally, and the above-mentioned characteristics are easily good, the above formula (3-a) 'is preferably represented by the following formula (3-1).

[Chemical 11]
In the formula, B, R ₁ , Ra, and Rb have the same meanings as the aforementioned B, R ₁ , Ra, and Rb. In the formula (3-1), when B is a carbon number of 1 and 2, and Ra and Rb are each a hydrogen atom, the formula (3-1) is represented by the formula (3-1a) and the formula (3-1b).

[Chemical 12]
In the formula, R ₁ and R _{1 have} the same meaning.

However, specific examples of the diamine represented by the formula (2) are not limited to the diamine represented by the formula (3). As long as the effect of the present invention is not impaired (for example, a low pretilt angle can be achieved), when the polymer is synthesized, a part of the diamine represented by the formula (2) or the formula (3) may be replaced with the following formula ( 5) Diamine.

> Diisocyanate used in the present invention>
The diisocyanate used in the present invention is represented by formula (4).

[Chemical 13]
In the formula, X represents a divalent organic group. The formula (4) is preferably represented by the formulas (4-1) to (4-11) and the formula (4-13).

[Chemical 14]

When the aliphatic diisocyanate represented by the formula (4-1) to the formula (4-5) is used, the polymerization obtained when compared with the aromatic diisocyanate represented by the formula (4-6) to the formula (4-13) is used. The substance will dissolve well in the solvent. On the other hand, the aromatic diisocyanate reacts well with the diamine better than the aliphatic diisocyanate. For example, the aromatic diisocyanates represented by formulas (4-6) and (4-7) react well with diamines, and can make the obtained liquid crystal alignment film have better heat resistance.

The consideration is to obtain the above-mentioned polymer with high versatility, and the obtained polymer has good characteristics. The formula (4) is preferably formula (4-1), formula (4-7), formula (4). -8), formula (4-9), or formula (4-10) are preferred. In addition, in consideration of the viewpoint that the obtained liquid crystal alignment film has good liquid crystal alignment, the formula (4) is preferably the formula (4-13).

However, if it is within the range of the interest of this invention, Formula (4) is not limited to the above. The diisocyanate which is easily available is ideally used in accordance with the target characteristics of the obtained polymer, liquid crystal alignment agent, liquid crystal alignment film, and the like. A diisocyanate may use 2 or more types together.

>Diamine>
When the above-mentioned polymer is obtained, a part of the diamine represented by the formula (2) may be replaced with another diamine (other diamine). In general, there are many types of diamines, and there are many compounds with organic groups having various functions. Therefore, by using other diamines in combination, it is possible to give further effects to the polymer or to make the diamine The above effects are further improved. The ratio of the molar number of other diamines to the molar number of diamines represented by formula (2) is arbitrary as long as the effect of the present invention is not impaired (for example, a low pretilt angle can be achieved). For example, the above ratio may be 0.5 or less. Of course, other diamines may not be used in combination. Such another diamine is, for example, a diamine represented by the following formula (5).

[Chemical 15]
In the formula, Y represents a divalent organic group. The structure of Y includes, for example, the following formulae (Y-1) to (Y-49) and (Y-57) to (Y-175), but is not limited thereto. R _{5 is} each independently a hydrogen atom, a methyl group, or an ethyl group. The reaction of tetracarboxylic dianhydride with diamine will provide polyamidic acid, and the reaction of diisocyanate with diamine will provide polyurea.

[Chemical 16]

[Chem. 17]

[Chemical 18]

[Chemical 19]

[Chemical 20]

[Chemical 21]

[Chemical 22]

[Chemical 23]
In the formula, unless otherwise specified, n is an integer of 1 to 6.

>Polymers>
The polymers based on polyurea and polyurea copolymers refer to polyurea and / or polyurea copolymer polymers. This polymer is represented by Formula (1).

[Chemical 24]
In the formula, X represents a divalent organic group derived from a diisocyanate, and Y represents a divalent organic group derived from a diamine. R ₁ represents an alkyl group having 1 to 4 carbon atoms, and may be branched. R ₂ represents a hydrogen atom, an aliphatic hydrocarbon group having 1 to 4 carbon atoms, or an organic group represented by the following formula (1-1). Ra and Rb each independently represent a hydrogen atom or an aliphatic hydrocarbon group having 1 to 2 carbon atoms.

[Chemical 25]
Wherein the portion of black dots junction bond of a nitrogen atom, R _1, Ra and Rb above, and R _1, Ra and Rb have the same meaning.

Polyurea is a strong hydrogen bond that is bonded by utilizing the polarity of the urea bond site. Therefore, the obtained film has excellent mechanical strength. On the other hand, this strong hydrogen bonding force becomes the cause of polymer agglomeration, which sometimes makes the stability of the polymer solution poor, etc. (the viscosity of the polymer solution increases, a part of the polymer is analyzed, the polymer solution gels, etc. ). Therefore, depending on the structure of the polyurea, the solvents that can be used are limited. For example, solvents with high polarity and high boiling point must be used.

The polymer has a structure represented by the formula (1), that is, a structure in which an organic group represented by the formula (1-1) is substituted on the N atom of the polyurea. The organic group represented by the formula (1-1) prevents hydrogen bond formation, thereby preventing polymers from agglomerating with each other. Therefore, the stability of the polymer solution is greatly improved. Therefore, when a polymer solution of polyurea is obtained, the choice of solvents that can be used will be broadened, and it can even be calcined at low temperatures to greatly improve printability. In addition, depending on the calcination temperature at the time of film formation, the urea bond site may form a hydantoin ring and intermolecular cross-linking.

> Reaction Solution>
As far as the reaction solution (the organic solvent used for the reaction to obtain the polymer described above) is concerned, there is no particular limitation as long as it is a solution in which the polymer described above can be dissolved. Specific examples thereof include N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, and N-methylhexanone Lactamine, dimethylmethylene, tetramethylurea, pyridine, dimethylfluorene, hexamethylmethylene, γ-butyrolactone, isopropanol, methoxymethylpentanol, dipentene, Ethylpentyl ketone, methyl nonyl ketone, methyl ethyl ketone, methyl isoamyl ketone, methyl isopropyl ketone, methyl cyperidine, ethyl cyperidine, methyl cyperidine acetate, ethyl Kisperithine acetate, butylcarbitol, ethylcarbitol, ethylene glycol, ethylene glycol monoacetate, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, propylene glycol, propylene glycol Monoacetate, propylene glycol monomethyl ether, propylene glycol-third butyl ether, dipropylene glycol monomethyl ether, diethylene glycol, diethylene glycol monoacetate, diethylene glycol dimethyl ether, dipropylene glycol monoacetic acid Ester monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monoacetate monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monoacetate monopropyl ether, 3-methyl-3-methoxy Butyl acetate, tripropylene glycol methyl ether, 3-methyl 3-Methoxybutanol, diisopropyl ether, ethyl isobutyl ether, diisobutylene, pentyl acetate, butyl butyrate, butyl ether, diisobutyl ketone, methylcyclohexene, propyl ether , Dihexyl ether, dioxane, n-hexane, n-pentane, n-octane, diethyl ether, cyclohexanone, ethyl carbonate, propylene carbonate, methyl lactate, ethyl lactate, methyl acetate, acetic acid Ethyl acetate, n-butyl acetate, propylene glycol monoethyl ether, methyl pyruvate, ethyl pyruvate, methyl 3-methoxypropionate, methyl ethyl 3-ethoxypropionate, 3-methoxy Ethyl propionate, 3-ethoxypropionic acid, 3-methoxypropionic acid, propyl 3-methoxypropionate, butyl 3-methoxypropionate, diglyme, 4-hydroxy 4-methyl-2-pentanone, 3-methoxy-N, N-dimethylpropanehydrazone, 3-ethoxy-N, N-dimethylpropanehydrazone, 3-butoxy -N, N-dimethylpropanamide and the like. They can be used alone or in combination of two or more. If it is the range which the said polymer does not precipitate, even the solution which does not dissolve the said polymer can be mixed and used for the said reaction solution.

In addition, the moisture in the reaction solution will hinder the polymerization reaction and cause the polymer to be hydrolyzed. Therefore, it is preferable to use a dehydrated and dried reaction solution. When a diisocyanate and a diamine react in a reaction solution, a method of stirring the reaction solution in which the diamine has been dispersed or dissolved, and directly adding the diisocyanate or dispersing or dissolving the reaction solution in the reaction solution and adding the method, or the method of dispersing Or a method of adding a diamine to a reaction solution in which a diisocyanate is dissolved, a method of alternately adding a diisocyanate and a diamine to a reaction solution, and the like may be used.

In addition, when a diisocyanate or a diamine is composed of a plurality of types of compounds, they can be reacted in a pre-mixed state, or they can be individually reacted sequentially, and low-molecular-weight bodies of individual reactions can also be mixed to form high-molecular-weight bodies. . The polymerization temperature at this time can be selected from any temperature of -20 ° C to 150 ° C, preferably in the range of -5 ° C to 100 ° C. In addition, the reaction can be carried out at any concentration. If the concentration is too low, it is difficult to obtain a polymer with a high molecular weight. If the concentration is too high, the viscosity of the reaction solution becomes too high, and it is difficult to uniformly stir. Therefore, the total concentration of diisocyanate and diamine in the reaction solution is preferably 1% by mass to 50% by mass, and more preferably 5% by mass to 30% by mass. The reaction is initially performed at a high concentration, and a reaction solution may be added thereafter.

In the polymerization reaction of polyurea, the ratio of the total mole number of the diisocyanate to the total mole number of the diamine is preferably 0.8 to 1.2. As with the usual polycondensation reaction, the closer this mole ratio is to 1.0, the larger the molecular weight of the polymer produced.

[Recycling of polymers]
In order to recover the polymer produced from the reaction solution, the reaction solution may be added to a poor solvent and the polymer may be precipitated. Examples of the poor solvent include methanol, acetone, hexane, butylcythrene, heptane, methyl ethyl ketone, methyl isobutyl ketone, ethanol, toluene, benzene, and water. The polymer which has been poured into a poor solvent and precipitated is filtered and recovered, and then it can be dried at normal temperature or under normal pressure or reduced pressure. In addition, if the recovered polymer is re-dissolved in an organic solvent, and the operations of reprecipitation and re-recovery are repeated 2 to 10 times, impurities in the polymer can be reduced. Poor solvents at this time are, for example, alcohols, ketones, hydrocarbons, and the like. If three or more kinds of poor solvents selected from these are used, the purification efficiency can be further improved, which is preferable.

The molecular weight of the polymer is determined by GPC (Gel Permeation Chromatography) method when considering the strength of the coating film obtained from the polymer, the ease of operation when forming the coating film, and the uniformity of the coating film thickness. The average molecular weight is preferably from 5,000 to 1,000,000, more preferably from 10,000 to 150,000.

> Liquid crystal alignment agent>
One aspect of the liquid crystal alignment agent of the present invention is a coating liquid for forming a liquid crystal alignment film, and a resin component for forming a coating film (resin coating film) is dissolved in an organic solvent. The resin component contains at least one of the aforementioned polymers. The content of the resin component in the liquid crystal alignment agent is preferably 2% to 20% by mass, more preferably 3% to 15% by mass, and even more preferably 3% to 10% by mass. In the present invention, all of the polymers contained in the resin component may be the above-mentioned polymers, and within the scope of the present invention, they may contain other polymers (other polymers). The content of the other polymer in the resin component is 0.5% by mass to 15% by mass, and preferably 1% by mass to 10% by mass. The other polymers are, for example, acrylic polymers, methacrylic polymers, novolac resins, polyhydroxystyrene, polyimide precursors, polyimides, polyimides, polyesters, celluloses, polymers Siloxane, etc.

The organic solvent used for the liquid crystal alignment agent is not particularly limited as long as it is an organic solvent that dissolves a resin component. Specific examples thereof include N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methylcaprolactam, 2-pyrrolidone, N -Ethylpyrrolidone, N-vinylpyrrolidone, dimethyl fluorene, tetramethylurea, pyridine, dimethyl fluorene, hexamethyl fluorene, γ-butyrolactone, 3-methoxy-N, N -Dimethylpropaneamide, 3-ethoxy-N, N-dimethylpropaneamide, 3-butoxy-N, N-dimethylpropaneamide, 1,3-dimethyl- Imidazolidone, ethylamyl ketone, methyl nonyl ketone, methyl ethyl ketone, methyl isoamyl ketone, methyl isopropyl ketone, cyclohexanone, ethylene carbonate, propylene carbonate, diethylene glycol Ether, 4-hydroxy-4-methyl-2-pentanone, etc. They can be used alone or in combination of two or more.

The liquid crystal alignment agent may contain components other than the above. Examples are solvents, compounds that make the film thickness uniformity of the coating film formed by applying the liquid crystal alignment agent, and surface smoothness, or compounds that make the adhesion between the liquid crystal alignment film and the substrate better.

Solvents (poor solvents) that make film thickness uniformity and surface smoothness better are solvents with low surface tension, such as isopropanol, methoxymethylpentanol, methylcythrene, ethyl Saipansu, Butylsaisin, Methylsaisin acetate, Ethylsaisin acetate, Butylcarbitol, Ethylcarbitol, Ethylcarbitol acetate, B Glycol, ethylene glycol monoacetate, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, propylene glycol, propylene glycol monoacetate, propylene glycol monomethyl ether, propylene glycol-third butyl ether, dipropylene glycol monomethyl ether Ether, diethylene glycol, diethylene glycol monoacetate, diethylene glycol dimethyl ether, dipropylene glycol monoacetate monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monoacetic acid Esters monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monoacetate monopropyl ether, 3-methyl-3-methoxybutyl acetate, tripropylene glycol methyl ether, 3-methyl-3-methoxy Butyl alcohol, diisopropyl ether, ethyl isobutyl ether, diisobutylene, pentyl acetate, butyl butyrate, butyl ether, diisobutyl ketone, methylcyclohexene, propyl ether, dihexyl ether 1-self , N-hexane, n-pentane, n-octane, diethyl ether, methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, n-butyl acetate, propylene glycol monoethyl ether, methyl pyruvate, ethyl pyruvate , Methyl 3-methoxypropionate, methyl ethyl 3-ethoxypropionate, ethyl 3-methoxypropionate, 3-ethoxypropionic acid, 3-methoxypropionic acid, 3 -Propyl methoxypropionate, butyl 3-methoxypropionate, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, 1-butoxy-2-propane Alcohol, 1-phenoxy-2-propanol, propylene glycol monoacetate, propylene glycol diacetate, propylene glycol-1-monomethyl ether-2-acetate, propylene glycol-1-monoethyl ether-2-acetic acid Esters, dipropylene glycol, 2- (2-ethoxypropoxy) propanol, methyl lactate, ethyl lactate, n-propyl lactate, n-butyl lactate, isoamyl lactate, and the like. These poor solvents may be used singly or in combination. When the above poor solvent is used, it is preferably 5 to 80% by mass of the entire organic solvent contained in the liquid crystal alignment agent, and more preferably 20 to 60% by mass.

Examples of the compound that improves the uniformity of the film thickness and the smoothness of the coating film surface include fluorine-based surfactants, polysiloxane-based surfactants, and non-ionic surfactants. More specifically, for example: EFTOP EF301, EF303, EF352 (manufactured by Tohkem Products), MegafacF171, F173, R-30 (manufactured by Dainippon Ink), Fluorad FC430, FC431 (manufactured by Sumitomo 3M), AsahiGuard AG710, surflon S-382, SC101, SC102, SC103, SC104, SC105, SC106 (made by Asahi Glass Co., Ltd.), etc. The use ratio of these surfactants is preferably 0.01 to 2 parts by mass, and more preferably 0.01 to 1 part by mass relative to 100 parts by mass of the resin component contained in the liquid crystal alignment agent.

Specific examples of the compound that improves the adhesion between the liquid crystal alignment film and the substrate include functional silane-containing compounds and epoxy-group-containing compounds as shown below. For example: 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 2-aminopropyltrimethoxysilane, 2-aminopropyltriethoxysilane, N- (2-Aminoethyl) -3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-ureapropyl Trimethoxysilane, 3-ureapropyltriethoxysilane, N-ethoxycarbonyl-3-aminopropyltrimethoxysilane, N-ethoxycarbonyl-3-aminopropyltriethoxy Silyl, N-triethoxysilylpropyltriethylenetriamine, N-trimethoxysilylpropyltriethylenetriamine, 10-trimethoxysilyl-1,4,7-triazadecyl Alkane, 10-triethoxysilyl-1,4,7-triazadecane, 9-trimethoxysilyl-3,6-diazanonylacetate, 9-triethoxy Silyl-3,6-diazanonyl acetate, N-benzyl-3-aminopropyltrimethoxysilane, N-benzyl-3-aminopropyltriethoxysilane, N -Phenyl-3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltriethoxysilane, N-bis (oxyethyl) -3-aminopropyltrimethoxy Silyl, N-bis (oxyethyl) -3-aminopropyltriethoxysilane , Ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, neopentyl glycol diepoxy Propyl ether, 1,6-hexanediol diglycidyl ether, glycerol diglycidyl ether, 2,2-dibromoneopentadiol diglycidyl ether, 1,3,5,6-tetracyclic Oxypropyl-2,4-hexanediol, N, N, N ', N' '-tetraepoxypropyl-m-xylylenediamine, 1,3-bis (N, N-diglycidylamino) (Meth) cyclohexane, N, N, N ', N' '-tetraepoxypropyl-4, 4'-diaminodiphenylmethane, and the like.

In addition to improving the adhesion between the substrate and the film, in order to prevent the decrease in electrical characteristics caused by light irradiation due to the backlight, the following phenoplast-based additives may be added. Specific phenolic plastic additives are shown below, but are not limited to this structure.

[Chem. 26]

When a compound that improves the adhesion between the substrate and the film is used, the amount of the compound used is preferably 0.1 to 30 parts by mass, more preferably 1 to 30 parts by mass, based on 100 parts by mass of the resin component contained in the liquid crystal alignment agent. 20 parts by mass. If the amount used is less than the above-mentioned 値, the adhesion may not be easily improved, and if it exceeds the above-mentioned 値, the liquid crystal alignment may be deteriorated.

In the liquid crystal alignment agent, in addition to the solvents and compounds described above, if the range of the effect of the present invention is not impaired, in order to change the electrical properties such as the dielectric constant and conductivity of the liquid crystal alignment film, and to make the dielectric body, conductive material, and further When the liquid crystal alignment film is made, the hardness and the density of the film are improved, and a predetermined crosslinkable compound may be added.

> Liquid crystal alignment film, liquid crystal display element>
After the above-mentioned liquid crystal alignment agent is coated on the substrate and calcined, the liquid crystal alignment film according to one aspect of the present invention can be obtained by performing alignment treatment with friction, light irradiation, or the like. As the substrate, a glass substrate with high transparency, or a plastic substrate (for example, an acrylic substrate or a polycarbonate substrate) can be used. In addition, 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 process of manufacturing a liquid crystal display element. Furthermore, in a reflective liquid crystal display element, an opaque object such as a silicon wafer can be used on a single-sided substrate, and at this time, an electrode that can reflect light such as aluminum can also be used. The method for applying the liquid crystal alignment agent is not particularly limited. In industry, spin coating printing, screen printing, lithographic printing, flexographic printing, inkjet printing, and the like are generally used. Other coating methods include dip coating, roll coating, slit coating, and spin coating. These methods can be used according to the purpose.

The calcination can be performed at a temperature of 50 ° C to 300 ° C, preferably 80 ° C to 250 ° C, using a heating means such as a hot plate. A coating film can be formed by evaporating the organic solvent in the liquid crystal alignment agent. If the thickness of the coating film is too thick, it is easy to increase the power consumption of the liquid crystal display element. If it is too thin, the reliability of the liquid crystal display element may be reduced. Therefore, it is preferably 5 nm to 300 nm, and more preferably 10 nm to 150 nm. When the liquid crystal is aligned horizontally and obliquely, the calcined coating film is subjected to alignment treatment by rubbing or polarized ultraviolet radiation.

According to the method described above, after a substrate with a liquid crystal alignment film is obtained from the liquid crystal alignment agent, a liquid crystal cell is produced by a known method to obtain a liquid crystal display element according to one aspect of the present invention. As an example of a method for manufacturing a liquid crystal cell, a pair of substrates having a liquid crystal alignment film formed thereon can be prepared, and a spacer is spread on the liquid crystal alignment film of one of the substrates so that the liquid crystal alignment film surface becomes the inner side and the other substrate is bonded. , The method of injecting and sealing liquid crystal under reduced pressure. Or, after the liquid crystal alignment film on which the spacers have been dispersed is dropped on the liquid crystal surface, the substrate is bonded and sealed. The thickness of the spacer at this time is preferably 1 μm to 30 μm, and more preferably 2 μm to 10 μm. The liquid crystal display element produced by using the liquid crystal alignment agent is excellent in reliability, so it is suitable for a large-screen and high-definition liquid crystal television.
[Example]

> Synthesis of Diamine>
Example 1
Synthesis of ethyl (4-aminobenzyl) glycinate [NG4ABA]

[Chemical 27]

Step 1 In a 1-liter 4-neck flask equipped with a nitrogen introduction tube and a reflux tube, add 105.6 g (0.694 mol) of ethyl glycine, 500 g of THF, and 93.6 g (0.925 mol) of triethylamine. Use a mechanical stirrer After stirring at room temperature for 1 hour, it was heated at a temperature at which THF refluxed (set at 70 ° C) to dissolve 50.0 g (0.231 mol) of 4-nitrobenzyl bromide in 500.0 g of THF, and slowly added dropwise. The reaction was continued for another 24 hours. When the 4-nitrobenzyl bromide disappeared, the reaction was completed. The precipitated solid was removed by filtration, and THF was removed on a rotary evaporator. The obtained crude product was redissolved in 300.0 g of ethyl acetate. This solution was washed three times with 100 g of pure water, 300 g of a 10% hydrochloric acid aqueous solution was added, and the mixture was stirred for one hour. The water layer side was recovered, and the water layer was washed three times with 100 g of ethyl acetate. 300 g of ethyl acetate was further added to the aqueous layer, potassium carbonate was slowly added to adjust the pH to about 10, and the mixture was stirred for 1 hour to recover the organic phase side, and washed with 100 g of pure water three times. Anhydrous magnesium sulfate is added to this organic phase, dried and filtered, activated carbon is added, and after stirring for a period of time, the activated carbon is removed by filtration, and the solvent is removed by a rotary evaporator to obtain a target (nitro body) pale yellow sticky substance. 46.0 g (0.193 mol). It was confirmed by ¹ H-NMR that the objective was obtained.
¹ H NMR (500MHz, CDCl ₃ ): δ 8.2 (2H), 7.53 (2H), 4.22 (2H), 3.93 (2H), 3.42 (2H), 1.89 (1H), 1.27 (3H)

Step 2 In a 500 ml 4-neck flask equipped with a nitrogen introduction tube and a stirrer, add 45.0 g (0.19 mol) of the nitro body obtained above, 300.0 g of THF, and 4.5 g of doped iron-type platinum carbon, and carefully replace the inside of the container. A hydrogen atmosphere was formed, and the reaction was performed at room temperature for 24 hours. When the reaction disappeared when the raw materials disappeared, platinum carbon was removed with a filter membrane, activated carbon (manufactured by Egret) was added to the filtrate, and the mixture was stirred at 40 ° C for 30 minutes. After that, it was filtered again, and the solvent was removed on a rotary evaporator, followed by drying with a high vacuum pump to obtain 35.4 g (0.17 mol: yield 89%) of a light yellow sticky substance as a target substance. It was confirmed by ¹ H-NMR that the target compound (NG4ABA) was obtained.
¹ H NMR (500MHz, CDCl ₃ ): δ 6.99 (2H), 6.63 (2H), 4.15 (2H), 3.70 (2H), 3.38 (2H), 3.00 (2H), 1.24 (3H)

Example 2
Synthesis of ethyl (3-aminobenzyl) glycinate [NG3ABA]

[Chemical 28]

The 4-nitrobenzyl bromide, which was the raw material in Example 1, was changed to 3-nitrobenzyl bromide and synthesized. A light yellow solid was obtained as the object (NG3ABA) with a yield of 37.4 g (0.18 mol: 94%). It was confirmed by ¹ H-NMR that the objective was obtained.
¹ H NMR (500MHz, CDCl ₃ ): δ 7.10 (1H), 6.65 (1H), 6.57 (1H), 4.16 (2H), 3.70 (2H), 3.39 (2H), 3.09 (2H), 1.25 (3H)

Example 3
Synthesis of (4-aminophenethyl) glycinate (ethyl (4-aminophenethyl) glycinate) [NG4APhA] [Chem. 29]

Step 1 In a 1 L 4-neck flask equipped with a nitrogen introduction tube and a reflux tube, add 50 g (0.246 mol) of 4-nitrophenethylamine hydrochloride, 500 g of THF, and 62.1 g (0.604 mol) of triethylamine. The stirrer was stirred at room temperature for 1 hour, and heated at a temperature at which THF was refluxed (set at 70 ° C.) to dissolve 25.1 g (0.205 mol) of ethyl 2-chloroacetate in 300 g of THF, and slowly add it dropwise. After the dropwise addition was completed, The reaction was continued for another 24 hours. When the 2-chloroethyl acetate disappeared (confirmed by HPLC) as the end of the reaction, the precipitated solid was removed by filtration, THF was removed on a rotary evaporator, and the obtained crude product was redissolved in 500 g of ethyl acetate. This solution was washed three times with 100 g of pure water, 500 g of a 10% hydrochloric acid aqueous solution was added, and the mixture was stirred for one hour. The water layer side was recovered, and the water layer was washed three times with 100 g of ethyl acetate. 500 g of ethyl acetate was further added to the aqueous layer, potassium carbonate was slowly added, the pH was adjusted to about 10, and the mixture was stirred for 1 hour to recover the organic phase side and washed 3 times with 100 g of pure water. Anhydrous magnesium sulfate was added to this organic phase, dried, filtered, and activated carbon was added. After stirring for a period of time, the activated carbon was removed by filtration, and the solvent was removed by a rotary evaporator to obtain 34.2 g of a pale yellow sticky substance (0.136 mol: 66% yield). It was confirmed by ¹ H-NMR that the target substance (nitro body) was obtained.
¹ H NMR (500MHz, CDCl ₃ ): δ 8.14 (2H), 7.37 (2H), 4.16 (2H), 3.43 (2H), 2.95 (4H), 2.19 (1H), 1.25 (3H)

Step 2 In a 500 ml 4-neck flask equipped with a nitrogen introduction tube and a stirrer, add 30.0 g of the nitro body obtained above, 300 g of THF, and 3.0 g of iron-doped platinum carbon, and carefully replace the inside of the container with a hydrogen atmosphere at room temperature. The reaction took 24 hours. When the reaction disappeared when the raw materials disappeared, platinum carbon was removed with a filter membrane, activated carbon (manufactured by Egret) was added to the filtrate, and the mixture was stirred at 40 ° C for 30 minutes. After that, it was filtered again, and the solvent was removed on a rotary evaporator, followed by drying with a high vacuum pump to obtain 25.1 g (0.113 mol: 95% yield) of a pale yellow sticky substance (NG4APhA). It was confirmed by ¹ H-NMR that the objective was obtained.
¹ H NMR (500MHz, CDCl ₃ ): δ 6.99 (2H), 6.60 (2H), 4.18 (2H), 3.42 (2H), 2.89 (2H), 2.86 (2H), 2.75 (2H), 1.24 (3H)

> Short name etc.>
Abbreviations for the preparation and use of liquid crystal alignment agents are as follows.
(Diisocyanate)
IDI: isophorone diisocyanate
4IBI: (isocyanoxymethyl) phenyl-isocyanate
DI-3MG: 1,3-bis (4-isocyanoxyphenoxy) propane
DI-2MG: 1,2-bis (4-isocyanoxyphenoxy) ethane

[Hua 30]

(Diamine)
NG4ABA: (4-aminobenzyl) glycine ethyl ester
NG3ABA: (3-aminobenzyl) glycine ethyl ester
NG4APhA: (4-aminophenylethyl) glycine ethyl ester
Me3ABA: N-methyl-3-aminobenzylamine
Me4APhA: N-methyl-4-aminophenethylamine
DA-3MG: 1,3-bis (4-aminophenoxy) propane

[Chemical 31]

(Solvent)
NMP: N-methyl-2-pyrrolidone
BCS: Butyl Saipan Su
GBL: gamma butyrolactone

The molecular weight measurement conditions of polyimide are as follows.
Device: Room temperature gel permeation chromatography (GPC) device (SSC-7200) manufactured by SENSHU Science Co., Ltd.
Column: Shodex Column (KD-803, KD-805)
Column temperature: 50 ℃
Eluent: N, N'-dimethylformamide (as an additive, lithium bromide-hydrate (LiBr · H ₂ O): 30mmol / L, phosphoric acid / anhydrous crystal (orthophosphoric acid): 30mmol / L, THF: 10ml / L)
Flow rate: 1.0ml / standard sample for production of measuring line: TSK standard polyethylene oxide (molecular weight of approximately 9000,000, 150,000, 100,000, 30,000) manufactured by Tosoh Corporation and polyethylene glycol (molecular weight of Polymer Laboratory) (Approximately 12,000, 4,000, 1,000)

> Synthesis of Polymers>
Example 4
DI-2MG / NG3ABA
Measure 1.00g (4.80mmol) of NG3ABA in a 50ml two-necked flask equipped with a nitrogen introduction tube and stirrer, add 13.43g of NMP to dissolve it, add 1.37g (4.60mmol) of DI-2MG, and place in a nitrogen atmosphere at The reaction was carried out at 40 ° C for 24 hours. Thereby, a polymer (polymer solution: P-1) having a concentration of 15% by mass and a viscosity of 420 mPas was obtained. The weight average molecular weight of the obtained polymer was Mw: 46200.

Example 5
DI-2MG / NG4ABA
Measure 1.00g (4.80mmol) of NG4ABA in a 50ml two-neck flask equipped with a nitrogen introduction tube and a stirrer, add 13.32g of NMP to dissolve it, add 1.35g (4.56mmol) of DI-2MG, and add The reaction was carried out at 40 ° C for 24 hours. Thus, a polymer (polymer solution: P-2) having a concentration of 15% by mass and a viscosity of 370 mPas was obtained. The weight average molecular weight of the obtained polymer was Mw: 39800.

Example 6
DI-3MG / NG4APhA
Measure 1.00g (4.50mmol) of NG4APhA in a 50ml two-necked flask equipped with a nitrogen introduction tube and a stirrer, add 13.20g of NMP to dissolve it, add 1.33g (4.28mmol) of DI-3MG, and place in a nitrogen atmosphere at The reaction was carried out at 40 ° C for 24 hours. Thereby, a polymer (polymer solution: P-3) having a concentration of 15% by mass and a viscosity of 440 mPas was obtained. The weight average molecular weight of the obtained polymer was Mw: 46300.

Example 7
4IBI / NG4APhA, DA-3MG
Measure NG4APhA 0.50g (2.25mmol) and DA-3MG 0.58g (2.25mmol) in a 50ml two-necked flask equipped with a nitrogen introduction tube and a stirrer, add NMP10.48g, dissolve it, and add 4IBI0.77g (4.41 mmol) and reacted at 40 ° C for 24 hours under a nitrogen atmosphere. Thereby, a polymer (polymer solution: P-4) having a concentration of 15% by mass and a viscosity of 280 mPas was obtained. The weight average molecular weight of the obtained polymer was Mw: 37300.

Example 8
IDI, DI-3MG / NG4ABA, DA-3MG
Measure NG4ABA 0.50g (2.40mmol) and DA-3MG 0.62g (2.40mmol) into a 50ml two-necked flask equipped with a nitrogen introduction tube and stirrer, add NMP13.60g, dissolve it, and add DI-3MG0.74g (2.40 mmol), IDI 0.54 g (2.42 mmol), and reacted at 40 ° C for 24 hours under a nitrogen atmosphere. Thereby, a polymer (polymer solution: P-5) having a concentration of 15% by mass and a viscosity of 330 mPas was obtained. The weight average molecular weight of the obtained polymer was Mw: 41600.

Comparative Example 1
DI-2MG / Me3ABA
Measure 1.00 g (7.34 mmol) of Me3ABA in a 50-ml two-necked flask equipped with a nitrogen introduction tube and a stirrer, add 19.36 g of NMP to dissolve it, and add 2.24 g (7.57 mmol) of DI-2MG. The reaction was carried out at 40 ° C for 24 hours. Thereby, a polymer (polymer solution: PRef-1) having a concentration of 15% by mass and a viscosity of 530 mPas was obtained. The weight average molecular weight of the obtained polymer was Mw: 39,900.

Comparative Example 2
DI-2MG / Me4APhA
Measure 1.00 g (6.66 mmol) of Me4APhA in a 50-ml two-necked flask equipped with a nitrogen introduction tube and a stirrer, add 16.38 g of NMP to dissolve it, and add 1.89 g (6.39 mmol) of DI-2MG in a nitrogen atmosphere. The reaction was carried out at 40 ° C for 24 hours. Thereby, a polymer (polymer solution: PRef-2) having a concentration of 15% by mass and a viscosity of 490 mPas was obtained. The weight average molecular weight of the obtained polymer was Mw: 41300.

> Preparation of liquid crystal alignment agent>
Example 9
In a 50 ml conical flask equipped with a stir bar, 10.0 g of the polymer (P-1) obtained in Example 4 was measured, 2.5 g of NMP, 5.0 g of GBL, and 7.5 g of BCS were added, and stirred at room temperature for 30 minutes to obtain a solid. Liquid crystal alignment agent (AL-1) with a composition of 6.0% by mass, NMP44% by mass, GBL20% by mass, and BCS30% by mass.

Example 10
In a 50 ml conical flask equipped with a stir bar, measure 10.0 g of the polymer (P-2) obtained in Example 5, add 2.5 g of NMP, 5.0 g of GBL, and 7.5 g of BCS, and stir at room temperature for 30 minutes to obtain a solid. Liquid crystal alignment agent (AL-2) with a composition of 6.0% by mass, NMP44% by mass, GBL20% by mass, and BCS30% by mass.

Example 11
In a 50 ml conical flask equipped with a stir bar, measure 10.0 g of the polymer (P-3) obtained in Example 6, add NMP 2.5 g, GBL 5.0 g, BCS 7.5 g, and stir at room temperature for 30 minutes to obtain a solid Liquid crystal alignment agent (AL-3) with a composition of 6.0% by mass, NMP44% by mass, GBL20% by mass, and BCS30% by mass.

Example 12
In a 50 ml conical flask equipped with a stir bar, measure 10.0 g of the polymer (P-4) obtained in Example 7, add NMP 2.5 g, GBL 5.0 g, and BCS 7.5 g, and stir at room temperature for 30 minutes to obtain a solid. Liquid crystal alignment agent (AL-4) with a composition of 6.0% by mass, NMP44% by mass, GBL20% by mass, and BCS30% by mass.

Example 13
In a 50 ml conical flask equipped with a stir bar, measure 10.0 g of the polymer (P-5) obtained in Example 8, add NMP 2.5 g, GBL 5.0 g, BCS 7.5 g, and stir at room temperature for 30 minutes to obtain a solid Liquid crystal alignment agent (AL-5) with a composition of 6.0% by mass, NMP44% by mass, GBL20% by mass, and BCS30% by mass.

Comparative Example 3
In a 50 ml conical flask equipped with a stir bar, 10.0 g of the polymer (PRef-1) obtained in Comparative Example 1 was weighed, 2.5 g of NMP, 5.0 g of GBL, and 7.5 g of BCS were added, and the mixture was stirred at room temperature for 30 minutes to obtain a solid. Liquid crystal alignment agent (AL-6) with a composition of 6.0% by mass, NMP44% by mass, GBL20% by mass, and BCS30% by mass.

Comparative Example 4
In a 50-ml conical flask equipped with a stir bar, 10.0 g of the polymer (PRef-2) obtained in Comparative Example 2 was measured, 2.5 g of NMP, 5.0 g of GBL, and 7.5 g of BCS were added, and the mixture was stirred at room temperature for 30 minutes to obtain a solid. Liquid crystal alignment agent (AL-7) with a composition of 6.0% by mass, NMP44% by mass, GBL20% by mass, and BCS30% by mass.

Comparative Example 5
As a liquid crystal alignment agent (AL-8), SE-6414 manufactured by Nissan Chemical Co., Ltd. was used.

The liquid crystal alignment films (AL-1 to AL-5) of Examples 9 to 13 and the liquid crystal alignment agents (AL-6 to AL-8) of Comparative Examples 3 to 5 were used to evaluate the liquid crystal alignment films according to the following methods.

> Evaluation of whitening resistance and coatability (printability)>
One drop of each of the obtained liquid crystal alignment agents was placed on a sufficiently cleaned Cr substrate, and it was left at room temperature of 25 ° C. and humidity of 60%, and the time until whitening (whitening) was measured. The whitening resistance was evaluated according to the measurement time.

After the liquid crystal alignment agent was filtered with a 1.0 μm filter, the coated Cr plate was subjected to flexographic printing using an alignment film printer (“ANGSTROMER” manufactured by Japan Photographic Printing Co., Ltd.) to perform a coating test.

About 1.0 ml of a liquid crystal alignment agent was added dropwise to the anilox roller, and after performing 10 dry runs, the printing machine was stopped for 10 minutes to dry the printing plate. Thereafter, printing was performed on one Cr substrate, and the printed substrate was placed on a hot plate at 70 ° C. for 5 minutes, and the coating film was temporarily dried to observe the film state. Visual observation and optical microscope ("ECLIPSE ME600" by Nikon Corporation) magnification of 50 times were mainly used to observe uneven film thickness and uneven film thickness at the edges.

> Evaluation of liquid crystal alignment, voltage retention, and pretilt angle>
[Observation of liquid crystal alignment and production of liquid crystal cell]
The liquid crystal alignment agent was filtered through a 1.0 μm filter, and then applied to a substrate with electrodes (a glass substrate having a size of 30 mm by 40 mm in length and a thickness of 1.1 mm by spin coating). The electrode system was a rectangle with a width of 10 mm and a length of 40 mm. ITO electrode with a thickness of 35 nm). After drying on a hot plate at 50 ° C for 5 minutes, it was calcined in an IR oven at 180 ° C for 20 minutes to form a coating film with a film thickness of 100 nm. This film was rubbed with a cloth (YA-20R manufactured by Yoshikawa Chemical Industry) (roller diameter: 120 mm, roller speed: 1000 rpm, moving speed: 20 mm / sec, push-in length: 0.4 mm), and then irradiated in pure water. Ultrasonic wave was washed for 1 minute, water droplets were removed by blowing air, and then dried at 80 ° C for 15 minutes to obtain a substrate with a liquid crystal alignment film.

Prepare two substrates with a liquid crystal alignment film as described above, and after spreading a 4 μm spacer on one of the liquid crystal alignment film surfaces, print a sealant thereon, and place the other substrate with the rubbing direction in the opposite direction and the film surface. After bonding in the right way, the sealant is hardened to produce an empty cell. To this empty cell, MLC-2041 (manufactured by Merck Co., Ltd.) was injected by a reduced pressure injection method, and the injection port was sealed to obtain a liquid crystal cell. Then, after observing the alignment of the liquid crystal, the liquid crystal cell was heated at 110 ° C. for 1 hour and left at 23 ° C. for a while to obtain a liquid crystal cell for measuring the voltage holding ratio.

The liquid crystal cell used for the measurement of the voltage holding ratio obtained by using the above program was applied with a voltage of 1V at a temperature of 60 s at a temperature of 60 ° C., the voltage after 166.7 ms was measured, and the degree of voltage holding was calculated as the voltage holding ratio. In addition, the measurement of the voltage holding ratio was performed using a VHR-1 voltage holding ratio measuring device manufactured by Toyo Technology.

[Evaluation of pretilt angle]
For the measurement of the pretilt angle, Axo Scan Mueller Matrix Polarimeter manufactured by Optometric was used.

[Evaluation of friction resistance]
After the liquid crystal alignment agent is filtered through a 1.0 μm filter, it is spin-coated and printed on a substrate with electrodes (a glass substrate with a size of 30 mm × 40 mm in length and a thickness of 1.1 mm. The electrode system has a rectangular shape with a width of 10 mm and a length of 40 mm. ITO electrode with a thickness of 35 nm). After drying on a hot plate at 50 ° C for 5 minutes, it was calcined in an IR oven at 180 ° C for 20 minutes to form a coating film with a film thickness of 100 nm. This film was rubbed with a cloth (YA-20R, manufactured by Yoshikawa Chemical Industry) (roller diameter: 120 mm, roller rotation speed: 1000 rpm, moving speed: 20 mm / sec, push-in length: 0.4 mm), and a confocal laser shot Microscope to evaluate friction resistance. It was rated as X when the film was peeled off, and it was rated as △ when many cutting residues and scratches were observed on the film, and ○ when good (when no film peeling was observed and many cutting residues and scratches were not observed on the film). Various evaluation results are shown in Table 1.

【Table 1】

The liquid crystal alignment agents of Examples 9 to 13 have much better whitening resistance and better printability than the comparative examples. Since Comparative Example 5 is a polyamino acid-based material, it is a material system having good whitening resistance and printability. Examples 9 to 13 are expected to have properties equivalent to or higher than Comparative Example 5 with respect to whitening resistance and printability. The organic group represented by the formula (1-1) is considered to be used in intramolecular reactions, cross-molecular crosslinks, and the like. Therefore, compared to Comparative Examples 3 and 4, the friction resistance of Examples 9 to 13 is very good. In Comparative Example 5, since the imidization reaction did not proceed, it was considered that the friction resistance was a poor result.

In addition, the liquid crystal cell obtained by using the liquid crystal alignment agent of Examples 9 to 13 can obtain a low pretilt angle and a high voltage holding ratio. It is presumed that the organic group represented by the formula (1-1) is used as a result of various reactions and does not accompany the decomposition reaction like polyamic acid. Therefore, the liquid crystal alignment film of one aspect of the present invention is considered to be very promising as a liquid crystal alignment film that can be calcined at a low temperature. Moreover, a liquid crystal alignment film and a liquid crystal display element can be obtained ideally also using the liquid crystal alignment agent in any of Examples 7-10.
[Industrial availability]

A liquid crystal display element produced using the liquid crystal alignment agent of the present invention can obtain a highly reliable liquid crystal display device, and can be ideally used for display elements using various methods such as an IPS liquid crystal display element and an FFS liquid crystal display element.

Claims (9)

A liquid crystal alignment agent comprising a polymer of a polyurea and a polyurea copolymer having a structure represented by the following formula (1); In the formula, X represents a divalent organic group derived from a diisocyanate derivative, and Y represents a divalent organic group derived from a diamine derivative; R ₁ represents an alkyl group having 1 to 4 carbon atoms, and may have branches; R ₂ Represents a hydrogen atom, an aliphatic hydrocarbon group having 1 to 4 carbon atoms, or an organic group represented by the following formula (1-1); Ra and Rb each independently represents a hydrogen atom or an aliphatic hydrocarbon group having 1 to 2 carbon atoms; Wherein the portion of black dots junction bond of a nitrogen atom, R _1, Ra and Rb above, and R _1, Ra and Rb have the same meaning. For example, the liquid crystal alignment agent of item 1 of the scope of patent application, a polymer containing a polyurea and a polyurea copolymer obtained from a diamine derivative and a diisocyanate derivative represented by the following formula (2); In the formula, A represents a divalent organic group of an aliphatic hydrocarbon group or an aromatic hydrocarbon group, and B and C each independently represent a single bond or an aliphatic hydrocarbon group having 1 to 5 carbon atoms; R ₁ , R ₂ , Ra, and Rb and the above R ₁ , R ₂ , Ra and Rb have the same meaning. For example, the liquid crystal alignment agent of the second scope of the patent application, a polymer containing polyurea and polyurea copolymer obtained from a diamine compound and a diisocyanate derivative represented by the following formula (3) in the diamine derivative ; In the formula, Ar represents an aryl group, and D represents a single bond or a hydrocarbon group having 1 to 5 carbon atoms; R ₁ , R ₂ , Ra, and Rb have the same meanings as the above-mentioned R ₁ , R ₂ , Ra, and Rb. For example, the liquid crystal alignment agent of the third scope of the application for a patent contains a polyurea and a polyurea copolymer obtained from a diamine compound and a diisocyanate derivative represented by the following formula (3-a) in the diamine derivative. polymer; In the formula, D and R _{1 have the} same meaning as those of D and R ₁ . A polymer obtained from a diamine compound and a diisocyanate derivative represented by the following formula (3-1); In the formula, R ₁ represents an alkyl group having 1 to 4 carbon atoms and may be branched; B represents a single bond or an aliphatic hydrocarbon group having 1 to 5 carbon atoms; Ra and Rb each independently represent a hydrogen atom or 1 to 3 carbon atoms; 2 aliphatic hydrocarbon group. For example, the polymer in item 5 of the scope of patent application is at least one of the diamino compound and the diisocyanate derivative represented by the following formulae (4-1) to (4-11) and formula (4-13) One gets . A liquid crystal alignment agent uses a polymer such as item 5 or 6 of the patent application scope. A liquid crystal alignment film is obtained from a liquid crystal alignment agent according to any one of claims 1 to 4, and 7 of the scope of patent application. A liquid crystal display element uses a liquid crystal alignment film such as the item No. 8 of the patent application scope.