KR102778109B1 - Liquid crystal alignment agent, polymer for obtaining same, liquid crystal alignment film, and liquid crystal display element using same - Google Patents

Abstract

The present invention relates to a liquid crystal alignment agent using a polymer obtained from a diamine derivative represented by the following formula (1), a diisocyanate derivative, and a monomer selected from a diamine or a diisocyanate having a specific side chain. In the formula, A represents a divalent organic group selected from 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 the formula (1-1). Ra and Rb each independently represent a hydrogen atom or an aliphatic hydrocarbon group having 1 to 2 carbon atoms.

Description

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

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

In liquid crystal display elements, the liquid crystal alignment film plays a role in aligning the liquid crystal in a certain direction. Currently, the main liquid crystal alignment film used industrially is formed by applying a polyimide-based liquid crystal alignment agent made of polyamic acid (also called polyimide precursor or polyamic acid) or polyimide solution to a substrate and firing it.

In order to improve the display characteristics of liquid crystal display elements, numerous technologies have been proposed. For example, in Patent Document 1 (Japanese Patent Application Laid-Open No. 2-287324), it is proposed to use a polyimide resin having a specific repeating structure to obtain a high voltage retention ratio (VHR). In addition, in Patent Document 2 (Japanese Patent Application Laid-Open No. 10-104633), it is proposed to use a soluble polyimide having nitrogen atoms other than imide groups to shorten the time until the afterimage disappears.

Japanese Government Publication No. 2-287324 Japanese Special Publication No. 10-104633

Recently, with the multifunctionalization and diversification of liquid crystal displays (LCD panels), development is progressing from displays using glass substrates to flexible displays using resin substrates (plastic substrates, i.e. film substrates). Accordingly, liquid crystal alignment films that can be obtained by low-temperature firing are required, and in addition, reliability (high voltage holding ratio, etc.) required for liquid crystal alignment films is also required.

Materials used in liquid crystal alignment films include polyimide precursors such as polyamic acid or polyamic acid ester, and polyimides obtained by dehydrating them through calcination or chemical reaction. Among these, polyamic acid is easy to synthesize and has excellent solubility in solvents, so a liquid crystal alignment agent with excellent coating properties and film-forming properties on a substrate can be obtained. However, polyamic acid is easily decomposed by hydrolysis or the like due to its structure, so it is difficult to ensure long-term reliability in a liquid crystal alignment film obtained using it.

On the other hand, since soluble polyimide (solvent-soluble polyimide obtained by dehydration reaction of polyamic acid) is pre-imidized, there is no need for a heat-curing process for heating to imidize, and therefore, firing at relatively low temperatures is possible. In addition, since it has excellent chemical stability and heat resistance, it is easy to secure reliability over the long term in a liquid crystal alignment film obtained using soluble polyimide. However, soluble polyimide has a limited choice of solvents in which it can be dissolved, and therefore, the solvents that can be used are limited, and as a result, when soluble polyimide is used, precipitation, etc. occur during application or film formation, and defects in the coating film are likely to occur. With the recent enlargement and refinement of LCD panels and the diversification of usage environments, there is a demand for the exploration of techniques that can solve each problem while improving various characteristics.

The present invention has been made in consideration of the above circumstances, and its object is to provide a liquid crystal alignment agent which can be fired at a low temperature and has good printability (solubility of the obtained polymer in an organic solvent). In addition, the object is to provide a polymer from which the above liquid crystal alignment agent can be obtained. In addition, the object is to provide a liquid crystal alignment film which has good liquid crystal alignment properties (i.e., can realize a high pretilt angle) and high voltage retention. In addition, the object is to provide a liquid crystal display element having the above liquid crystal alignment film.

The inventors of the present invention, as a result of extensive research, have found that a polymer having a specific structure and a liquid crystal alignment agent using the same are effective for achieving the above-mentioned purpose, thereby completing the present invention. In addition, the polymer is novel, and the monomer for obtaining the polymer also contains a novel compound.

That is, the present invention has the following points 1. to 10.

1. A liquid crystal alignment agent using a polymer obtained from a diamine derivative represented by the following formula (1), a diisocyanate derivative, and a monomer selected from a diamine or diisocyanate having a specific side chain:

[Chemical Formula 1]

In the formula, A represents a divalent organic group selected from 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, which 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.

2. A liquid crystal alignment agent described in 1., wherein the monomer containing the above specific side chain is represented by the following formula (2):

[Chemical formula 2]

In the formula, N represents an amino group or an isocyanate group, R ₃ represents a single bond or a divalent organic group, X ¹ , X ² , and X ³ each independently represent a benzene ring or a cyclohexane ring, p, q, and r each independently represent an integer of 0 or 1, and R ₄ represents a hydrogen atom, an alkyl group having 1 to 22 carbon atoms, or a divalent organic group having 12 to 25 carbon atoms and a steroid skeleton.

3. A liquid crystal alignment agent as described in 2, wherein the above diamine derivative is a diamino compound represented by the following formula (3):

[Chemical Formula 3]

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 meaning as R ₁ , R ₂ , Ra and Rb above.

4. A liquid crystal alignment agent as described in 3, wherein the above diamine derivative is a diamino compound represented by the following formula (3-a):

[Chemical Formula 4]

In the formula, D and R ₁ are synonymous with D and R ₁ above.

5. A polymer obtained from a diamino compound represented by the following formula (3-1), a diisocyanate derivative, and a monomer selected from a diamine or diisocyanate having a specific side chain:

[Chemical Formula 5]

In the formula, R ₁ represents an alkyl group having 1 to 4 carbon atoms, which 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 an aliphatic hydrocarbon group having 1 to 2 carbon atoms.

6. A polymer as described in 5, wherein the monomer containing the specific side chain is represented by the following formula (2):

[Chemical formula 6]

In the formula, N represents an amino group or an isocyanate group, R ₃ represents a single bond or a divalent organic group, X ¹ , X ² , and X ³ each independently represent a benzene ring or a cyclohexane ring, p, q, and r each independently represent an integer of 0 or 1, and R ₄ represents a hydrogen atom, an alkyl group having 1 to 22 carbon atoms, or a divalent organic group having 12 to 25 carbon atoms and a steroid skeleton.

7. A polymer as described in 6, wherein the diisocyanate derivative has at least one of the structures represented by the following formulae (4-1) to (4-13):

[Chemical formula 7]

In the formula, R ₅ and R ₆ each independently represent an aliphatic hydrocarbon group having 1 to 10 carbon atoms.

8. A liquid crystal alignment agent using a polymer described in any one of 5.∼7.

9. A liquid crystal alignment film obtained from a liquid crystal alignment agent described in any one of 1. to 4. and 8.

10. A liquid crystal display element using the liquid crystal alignment film described in 9.

According to the present invention, it is possible to provide a liquid crystal alignment agent which is capable of being fired at a low temperature, which can obtain a high-quality liquid crystal alignment film, and which has excellent printability. In addition, according to the present invention, it is possible to provide a novel polymer for obtaining the liquid crystal alignment agent. In addition, according to the present invention, it is possible to provide a liquid crystal alignment film which can realize a high pretilt angle and has a high voltage retention rate. In addition, according to the present invention, it is possible to provide a liquid crystal display element using the liquid crystal alignment film.

A liquid crystal alignment agent according to one embodiment of the present invention contains a polymer according to one embodiment of the present invention, which is obtained from a diamine derivative (hereinafter sometimes referred to as “diamine”) represented by formula (1), a diisocyanate derivative (hereinafter sometimes referred to as “diisocyanate”), and a monomer selected from a diamine or diisocyanate having a specific side chain (hereinafter sometimes referred to as a “side chain-containing monomer”).

＜Diamine used in the present invention＞

The diamine used in the present invention is represented by formula (1).

[Chemical formula 8]

In the formula, A represents a divalent organic group, such as 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, which 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.

From the viewpoint of being able to obtain a liquid crystal alignment film having excellent polymerization reactivity of a monomer, heat resistance, or liquid crystal alignment, it is preferable that in formula (1), A is an aromatic hydrocarbon group, B is an aliphatic hydrocarbon group having 1 to 3 carbon atoms, and C is a single bond. Specifically, formula (1) can include the following structures.

[Chemical formula 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 R ₁ , R ₂ , Ra and Rb above.

Considering the ease of obtaining a reagent for synthesizing diamine, the good reactivity with diisocyanate, and the good physical properties of the obtained polymer, in formula (3), Ar is preferably a phenyl group, and R ₂ is preferably a hydrogen atom. Therefore, formula (3) is preferably a structure represented by the following formula (3-a)'. Among these, in formula (3), it is preferable that Ra and Rb are each a hydrogen atom. Therefore, formula (3) is particularly preferably represented by formula (3-a).

[Chemical Formula 10]

In the formula, D and R ₁ are synonymous with D and R ₁ above.

From the viewpoints of being able to suitably obtain the target monomer and making it easy for all of the above properties to be improved, the above formula (3-a)' is preferably expressed by the following formula (3-1).

[Chemical Formula 11]

In the formula, B, R ₁ , Ra and Rb are synonymous with B, R ₁ , Ra and Rb above. In the formula (3-1), if B has 1 and 2 carbon atoms, 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 Formula 12]

In the formula, R ₁ is synonymous with R ₁ above.

However, specific examples of the diamine represented by formula (1) are not limited to the diamine represented by formula (3). In synthesizing the polymer, part of the diamine represented by formula (1) or formula (3) may be replaced with the diamine represented by formula (5) described below, as long as the effect of the present invention (for example, the ability to realize a high pretilt angle) is not impaired.

＜Diisocyanate used in the present invention＞

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

[Chemical Formula 13]

In the formula, X represents a divalent organic group. Formula (4) is preferably expressed by formulas (4-1) to (4-13).

[Chemical Formula 14]

In the formula, R ₅ and R ₆ each independently represent an aliphatic hydrocarbon group having 1 to 10 carbon atoms.

When an aliphatic diisocyanate represented by formulas (4-1) to (4-5) is used, the resulting polymer dissolves well in the solvent, compared to a case where an aromatic diisocyanate represented by formulas (4-6) to (4-13) is used. Meanwhile, the aromatic diisocyanate reacts well with diamine, compared to the aliphatic diisocyanate. For example, an aromatic diisocyanate such as that represented by formula (4-6) or formula (4-7) reacts well with diamine, and can improve the heat resistance of the resulting liquid crystal alignment film.

From the viewpoints of being a compound with high versatility in obtaining the above polymer, of improving the properties of the obtained polymer, etc., formula (4) is preferably formula (4-1), formula (4-7), formula (4-8), formula (4-9), or formula (4-10). In addition, from the viewpoint of improving the electrical properties of the obtained liquid crystal alignment film, formula (4-12) is preferable, and from the viewpoint of improving the liquid crystal alignment property of the obtained liquid crystal alignment film, formula (4-13) is preferable.

However, within the scope of the invention, formula (4) is not limited to the above. Depending on the target properties of the obtained polymer, liquid crystal alignment agent, and liquid crystal alignment film, etc., a diisocyanate that is easily available can be suitably used. Two or more types of diisocyanate may be used in combination.

＜Side chain containing monomer used in the present invention＞

The side chain-containing monomer used in the present invention is represented by formula (2).

[Chemical Formula 15]

In the formula, N represents an amino group or an isocyanate group, R ₃ represents a single bond or a divalent organic group, X ¹ , X ² , and X ³ each independently represent a benzene ring or a cyclohexane ring, p, q, and r each independently represent an integer of 0 or 1, and R ₄ represents a hydrogen atom, an alkyl group having 1 to 22 carbon atoms, or a divalent organic group selected from 12 to 25 carbon atoms having a steroid skeleton.

The side chain-containing monomer represented by formula (2) contributes to increasing the pretilt angle of the liquid crystal. When the side chain-containing monomer is a diamine, it is preferable that the diamine has a long-chain alkyl group, a perfluoroalkyl group, an aromatic cyclic group, an aliphatic cyclic group, a substituent combining these, a steroid skeletal group, etc. Since the preferable size of the pretilt angle varies depending on the display mode of the liquid crystal display, the target pretilt angle can be obtained by selecting various structures or introduction amounts of the side chain-containing monomer.

In the TN mode which requires a pretilt angle of 3° to 5°, which is lower than the VA mode described below, or in the OCB mode which requires a pretilt angle of 8° to 20°, it is preferable to use a side chain-containing monomer which has a relatively small function of increasing the pretilt angle (tilt expression ability). As the side chain-containing monomer which has a relatively small tilt expression ability, for example, in formula (2), R ₃ is preferably -O-, or -NHCO- (or -CONH-), p is preferably 0 to 1, q is preferably 0 to 1, r is preferably 0, and when p and/or q is 1, R ₄ is preferably a straight-chain alkyl group having 1 to 12 carbon atoms, and when p = q = r = 0, R ₄ is preferably a straight-chain alkyl group having 10 to 22 carbon atoms, or a divalent organic group which is an organic group having 12 to 25 carbon atoms and having a steroid skeleton. The specific structure of the side chain-containing monomer having a low tilt expression ability is shown in Table 1, but formula (2) is not limited to the structure in Table 1. In addition, in each of [2-16] to [2-30] in Table 1, "-NHCO-" of R ₁ can be read as "-CONH-".

[Table 1]

From the viewpoint of improving the electrical properties of the obtained liquid crystal alignment film, side chain-containing monomers having long-chain alkyl side chains such as [2-1] to [2-3] in Table 1 are preferable. In addition, from the viewpoint of being able to improve the liquid crystal alignment property and pretilt stability of the obtained liquid crystal alignment film, side chain-containing monomers represented by [2-25] to [2-27] in Table 1 are preferable.

Meanwhile, by using a side chain-containing monomer having a high tilt expression ability, it becomes easy for the liquid crystal to be vertically aligned. Therefore, as a structure of formula (2) in the VA mode, for example, R ₃ is preferably -O-, -COO-, or -CH ₂ O-, p is preferably 0 to 1, q is preferably 0 to 1, r is preferably 0 to 1, and R ₄ preferably has 2 to 22 carbon atoms. When p = q = r = 0, R ₄ is preferably a straight-chain alkyl group having 18 to 22 carbon atoms, or a divalent organic group having 12 to 25 carbon atoms and a steroid skeleton. Specific structures of the side chain-containing monomer having a high tilt expression ability are shown in Table 2-1 and Table 2-2, but formula (2) is not limited to the structures of Table 2-1 and Table 2-2.

[Table 2-1]

[Table 2-2]

The side chain-containing monomers of Table 2-1 and Table 2-2 are preferable when used in VA mode because they have high tilt expression ability. In particular, [2-43], [2-92], etc. have high tilt expression ability, so that even with a relatively small amount of side chains, they can easily vertically align the liquid crystal. In particular, [2-52] and [2-101] have extremely high tilt expression ability, so that even with a very small amount of side chains, they can vertically align the liquid crystal. Therefore, these side chain-containing monomers are preferable in terms of improving the printability of the liquid crystal alignment agent.

Meanwhile, the side chain-containing monomer represented by formula (2) is selected from diamine or diisocyanate. However, diisocyanate is derived by reacting highly toxic phosgene or the like with diamine. Therefore, from the viewpoint of easy acquisition of the side chain-containing monomer, it is simpler to use diamine as the side chain-containing monomer. Therefore, N in formula (2) is preferably an amino group.

Monomers that overlap in Table 1, Table 2-1, and Table 2-2 may be used in either the TN mode, OCB mode, or the VA mode. In obtaining the above polymer, the content of the side chain-containing monomer is arbitrary within the scope of the invention. For example, the number of moles of the side chain-containing monomer relative to the total number of moles of the diamine represented by Formula (1) and the side chain-containing monomer may be 0.05 to 0.5.

＜Diamine＞

In obtaining the above polymer, a part of the diamine represented by formula (1) may be replaced with another diamine (another diamine, that is, a diamine that does not correspond to the diamine represented by formula (1) and also does not correspond to a side chain-containing monomer). In general, since there are many types of diamines and many compounds having organic groups with various functions, by using another diamine in combination, an additional effect can be imparted to the polymer, or the effect of the diamine can be further enhanced. The ratio of the mole number of the other diamine to the mole number of the diamine represented by formula (1) is arbitrary within a range that does not impair the effect of the present invention (for example, being able to realize a high pretilt angle). Of course, it is not necessary to use another diamine in combination. As such another diamine, for example, a diamine represented by formula (5) below can be mentioned.

[Chemical Formula 16]

In the formula, Y represents a divalent organic group. Examples of specific structures of Y are listed as in the following formulas (Y-1) to (Y-147), but are not limited thereto. In the formulas (Y-1) to (Y-147), the black dots represent bonding sites to nitrogen atoms. R ₇ independently represents a hydrogen atom, a methyl group, or an ethyl group. In the reaction between tetracarboxylic dianhydride and a diamine, a polyamic acid is given, and in the reaction between diisocyanate and a diamine, a polyurea is given.

[Chemical Formula 17]

[Chemical Formula 18]

[Chemical Formula 19]

[Chemical Formula 20]

In formulas (Y-108) to (Y-112), A ₁ represents an alkyl group or a fluorine-containing alkyl group having 2 to 24 carbon atoms.

[Chemical Formula 21]

In formulas (Y-113) to (Y-114), A ₂ represents -O-, -OCH ₂ -, -CH ₂ O-, -COOCH ₂ -, or -CH ₂ OCO-, and A ₃ represents an alkyl group, an alkoxy group, a fluorine-containing alkyl group, or a fluorine-containing alkoxy group having 1 to 22 carbon atoms.

[Chemical Formula 22]

In formulas (Y-115) to (Y-117), A ₄ represents -COO-, -OCO-, -CONH-, -NHCO-, -COOCH ₂ -, -CH ₂ OCO-, -CH ₂ O-, -OCH ₂ -, or -CH ₂ -, and A ₅ represents an alkyl group, an alkoxy group, a fluorine-containing alkyl group, or a fluorine-containing alkoxy group having 1 to 22 carbon atoms.

[Chemical Formula 23]

In formulas (Y-118) to (Y-119), A ₆ represents -COO-, -OCO-, -CONH-, -NHCO-, -COOCH ₂ -, -CH ₂ OCO-, -CH ₂ O-, -OCH ₂ -, -CH ₂ -, -O-, or -NH-, and A ₇ represents a fluorine group, a cyano group, a trifluoromethane group, a nitro group, an azo group, a formyl group, an acetyl group, an acetoxy group, or a hydroxyl group.

[Chemical Formula 24]

In formulas (Y-120) to (Y-121), A ₈ represents an alkyl group having 3 to 12 carbon atoms, and the cis-trans isomers of 1,4-cyclohexylene are each trans isomers.

[Chemical Formula 25]

In formulas (Y-122) to (Y-123), A ₉ represents an alkyl group having 3 to 12 carbon atoms, and the cis-trans isomers of 1,4-cyclohexylene are each a trans isomer.

[Chemical Formula 26]

In formulas (Y-132) to (Y-137), A ₁₂ represents -COO-, -OCO-, -CONH-, -NHCO-, -CH ₂ -, -O-, -CO-, or -NH-, and A ₁₃ represents an alkyl group or a fluorine-containing alkyl group having 1 to 22 carbon atoms.

[Chemical formula 27]

In formula (Y-140), formula (Y-144), and formula (Y-145), n represents an integer from 1 to 10.

＜Polymer＞

The above polymer (polyurea and polyurea copolymer) is represented by formula (6).

[Chemical formula 28]

In the formula, X represents a divalent organic group derived from diisocyanate, and Y represents a divalent organic group derived from diamine. R ₁ represents an alkyl group having 1 to 4 carbon atoms, which 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 Formula 29]

In the formula, the black dots represent bonding sites to nitrogen atoms, and R ₁ , Ra and Rb are synonymous with R ₁ , Ra and Rb above.

Polyurea forms strong hydrogen bonds due to the polarity of the urea bonding site, so the resulting film has excellent mechanical strength. On the other hand, the strong hydrogen bonding force may cause polymer coagulation, which may worsen the stability of the polymer solution (increasing the viscosity of the polymer solution, precipitating part of the polymer, gelling of the polymer solution, etc.). Therefore, depending on the structure of the polyurea, the solvents that can be used are limited, and for example, it is necessary to use a solvent that is highly polar and has a high boiling point.

The above polymer has a structure represented by formula (6), that is, a structure in which an organic group represented by formula (1-1) is substituted on the N atom of polyurea. The organic group represented by formula (1-1) inhibits the formation of hydrogen bonds, thereby preventing aggregation of polymers. For this reason, the stability of the polymer solution is greatly improved. Therefore, in obtaining a polymer solution of polyurea, the range of usable solvents can be expanded, and further, low-temperature firing and greatly improved printability can also be achieved. In addition, depending on the firing temperature at the time of film formation, the site of the urea bond may form a hydantoin ring or an intermolecular crosslink.

＜Reaction solution＞

The reaction solution (organic solvent used in the reaction to obtain the above polymer) is not particularly limited as long as it is a solution in which the above polymer dissolves. Specific examples thereof include N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-methylcaprolactam, dimethylsulfoxide, tetramethylurea, pyridine, dimethylsulfone, hexamethylsulfoxide, γ-butyrolactone, isopropyl alcohol, methoxymethylpentanol, dipentene, ethylamyl ketone, methyl nonyl ketone, methyl ethyl ketone, methyl isoamyl ketone, methyl isopropyl ketone, methyl cellosolve, ethyl cellosolve, methyl cellosolve acetate, ethyl cellosolve acetate, butyl carbitol, ethyl carbitol, ethylene glycol, ethylene glycol monoacetate, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, propylene glycol, propylene glycol monoacetate, Propylene glycol monomethyl ether, propylene glycol-tert-butyl ether, dipropylene glycol monomethyl 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 monoacetate monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monoacetate monopropyl ether, 3-methyl-3-methoxybutyl acetate, tripropylene glycol methyl ether, 3-methyl-3-methoxybutanol, diisopropyl ether, ethyl isobutyl ether, diisobutylene, amyl acetate, butyl butyrate, butyl ether, diisobutyl ketone, methylcyclohexene, propyl ether, dihexyl ether, dioxane, n-hexane, n-pentane, n-octane, diethyl ether, cyclohexanone, ethylene carbonate, propylene carbonate, methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, n-butyl acetate, propylene glycol monoethyl ether acetate, methyl pyruvate, ethyl pyruvate, methyl 3-methoxypropionate, methyl ethyl 3-ethoxypropionate, ethyl 3-methoxypropionate, 3-ethoxypropionic acid, 3-methoxypropionic acid, propyl 3-methoxypropionate, butyl 3-methoxypropionate, diglyme, 4-hydroxy-4-methyl-2-pentanone, 3-methoxy-N,N-dimethylpropanamide, 3-ethoxy-N,N-dimethylpropanamide, 3-butoxy-N,N-dimethylpropanamide, etc. These may be used alone or in combination of two or more. As long as the polymer does not precipitate, even if it is a solution that does not dissolve the polymer, it may be mixed and used in the reaction solution.

In addition, since moisture in the reaction solution inhibits the polymerization reaction and further causes hydrolysis of the produced polymer, it is preferable to use a dehydrated and dried reaction solution. When reacting diisocyanate and diamine in the reaction solution, a method may be used in which the reaction solution in which diamine is dispersed or dissolved is stirred, and diisocyanate is added as it is or dispersed or dissolved in the reaction solution, conversely, a method in which diamine is added to the reaction solution in which diisocyanate is dispersed or dissolved, a method in which diisocyanate and diamine are alternately added to the reaction solution, etc., and any of these methods may be used.

In addition, when the diisocyanate or diamine is composed of multiple compounds, the reaction may be carried out in a pre-mixed state, the reactions may be carried out sequentially individually, or the individually reacted low-molecular-weight compounds may be mixed and reacted to form a high-molecular-weight compound. The polymerization temperature at that time can be any temperature from -20°C to 150°C, but is preferably in the range of -5°C to 100°C. In addition, the reaction can be carried out at any concentration, but if the concentration is too low, it becomes difficult to obtain a high-molecular-weight polymer, and if the concentration is too high, the viscosity of the reaction solution becomes too high, making uniform stirring difficult. Therefore, the total concentration in the reaction solution of the diisocyanate (the diisocyanate represented by formula (4)) and the diamine (the diamine represented by formulas (1) and (5)) is preferably 1 mass% to 50 mass%, more preferably 5 mass% to 30 mass%. The reaction may be carried out at a high concentration at the beginning, and the reaction solution may be added thereafter.

In the polymerization reaction of polyurea, the ratio of the total mole number of diisocyanate (diisocyanate represented by formula (4)) to the total mole number of diamine (diamine represented by formulas (1) and (5)) is preferably 0.8 to 1.2. As in a normal polycondensation reaction, the closer this mole ratio is to 1.0, the larger the molecular weight of the produced polymer.

[Polymer recovery]

In order to recover the polymer produced from the reaction solution, the reaction solution may be poured into a poor solvent to precipitate the polymer. Poor solvents include methanol, acetone, hexane, butyl cellosolve, heptane, methyl ethyl ketone, methyl isobutyl ketone, ethanol, toluene, benzene, water, etc. The polymer precipitated by pouring into a poor solvent can be recovered by filtration, and then dried at room temperature or by heating under normal pressure or reduced pressure. In addition, if the recovered polymer is redissolved in an organic solvent and the operations of reprecipitation and re-recovery are repeated 2 to 10 times, the impurities in the polymer can be reduced. Examples of the poor solvent at this time include alcohols, ketones, hydrocarbons, etc., and it is preferable to use three or more poor solvents selected from these because this further increases the purification efficiency.

The molecular weight of the polymer is preferably 5,000 to 1,000,000, more preferably 10,000 to 150,000, as measured by the weight average molecular weight (GPC) method, taking into account the strength of the coating film obtained from the polymer, the ease of work in forming the coating film, the uniformity of the film thickness, etc.

＜Liquid crystal orientation agent＞

The liquid crystal alignment agent according to one embodiment of the present invention is a coating solution for forming a liquid crystal alignment film, and a resin component for forming a coating film (resin film) is dissolved in an organic solvent. The resin component contains at least one of the above-described polymers. The content of the resin component in the liquid crystal alignment agent is preferably 2 to 20 mass%, more preferably 3 to 15 mass%, and particularly preferably 3 to 10 mass%. In the present invention, the polymer contained in the resin component may be all of the above-described polymers (polyurea and polyurea copolymer), and may contain other polymers (other polymers) as long as it is within the scope of the present invention. The content of the other polymer in the resin component is 0.5 to 15 mass%, and preferably 1 to 10 mass%. Such other polymers include, for example, acrylic polymers, methacrylic polymers, novolac resins, polyhydroxystyrene, polyimide precursors, polyimides, polyamides, polyesters, cellulose, polysiloxanes, etc.

The organic solvent used in the above liquid crystal alignment agent is not particularly limited as long as it is an organic solvent that dissolves the resin component. Specific examples thereof include N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methylcaprolactam, 2-pyrrolidone, N-ethylpyrrolidone, N-vinylpyrrolidone, dimethylsulfoxide, tetramethylurea, pyridine, dimethylsulfone, hexamethylsulfoxide, γ-butyrolactone, 3-methoxy-N,N-dimethylpropanamide, 3-ethoxy-N,N-dimethylpropanamide, 3-butoxy-N,N-dimethylpropanamide, 1,3-dimethylimidazolidinone, ethylamyl ketone, methylnonyl ketone, methyl ethyl ketone, methyl isoamyl ketone, methyl isopropyl ketone, cyclohexanone, ethylene carbonate, propylene carbonate, diglyme, 4-hydroxy -4-Methyl-2-pentanone, etc. can be used. These can be used alone or in combination of two or more types.

The above liquid crystal alignment agent may contain components other than those mentioned above. Examples thereof include solvents or compounds that improve the uniformity of the film thickness or the smoothness of the surface of a film formed by applying the liquid crystal alignment agent, or compounds that improve the adhesion between the liquid crystal alignment film and the substrate.

Solvents (poor solvents) which improve the uniformity of film thickness or surface smoothness include solvents having low surface tension, for example, isopropyl alcohol, methoxymethylpentanol, methyl cellosolve, ethyl cellosolve, butyl cellosolve, methyl cellosolve acetate, ethyl cellosolve acetate, butyl carbitol, ethyl carbitol, ethyl carbitol acetate, ethylene glycol, ethylene glycol monoacetate, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, propylene glycol, propylene glycol monoacetate, propylene glycol monomethyl ether, propylene glycol-tert-butyl ether, dipropylene glycol monomethyl 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 monoacetate monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monoacetate monopropyl ether, 3-methyl-3-methoxybutyl acetate, tripropylene glycol methyl ether, 3-methyl-3-methoxybutanol, diisopropyl ether, ethyl isobutyl ether, diisobutylene, amyl acetate, butyl butyrate, butyl ether, diisobutyl ketone, methylcyclohexene, propyl ether, dihexyl ether, 1-hexanol, n-hexane, n-pentane, n-octane, diethyl ether, methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, n-butyl acetate, propylene glycol monoethyl ether acetate, methyl pyruvate, ethyl pyruvate, methyl 3-methoxypropionate, methyl ethyl 3-ethoxypropionate, Examples thereof include 3-methoxypropionate ethyl, 3-ethoxypropionic acid, 3-methoxypropionic acid, propyl 3-methoxypropionate, butyl 3-methoxypropionate, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, 1-butoxy-2-propanol, 1-phenoxy-2-propanol, propylene glycol monoacetate, propylene glycol diacetate, propylene glycol-1-monomethyl ether-2-acetate, propylene glycol-1-monoethyl ether-2-acetate, dipropylene glycol, 2-(2-ethoxypropoxy)propanol, methyl lactate, ethyl lactate, n-propyl lactate, n-butyl lactate, and isoamyl lactate. These poor solvents may be used alone or in combination. When the above-mentioned empty solvent is used, it is preferably 5 mass% to 80 mass% of the total organic solvent contained in the liquid crystal alignment agent, more preferably 20 mass% to 60 mass%.

Examples of compounds that improve the uniformity of film thickness or the smoothness of the film surface include fluorinated surfactants, silicone surfactants, and nonionic surfactants. More specifically, examples thereof include Eptop EF301, EF303, EF352 (manufactured by Tochem Products Co., Ltd.), Megapak F171, F173, R-30 (manufactured by Dainippon Ink Co., Ltd.), Florard FC430, FC431 (manufactured by Sumitomo 3M Co., Ltd.), Asahi Guard AG710, Surflon S-382, SC101, SC102, SC103, SC104, SC105, SC106 (manufactured by Asahi Glass Co., Ltd.). The usage ratio of these surfactants is preferably 0.01 to 2 parts by mass, more preferably 0.01 to 1 part by mass, per 100 parts by mass of the resin component included in the liquid crystal alignment agent.

Specific examples of compounds that improve adhesion between the liquid crystal alignment film and the substrate include the following functional silane-containing compounds and epoxy group-containing compounds. For example, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 2-aminopropyltrimethoxysilane, 2-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-ureidopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, N-ethoxycarbonyl-3-aminopropyltrimethoxysilane, N-ethoxycarbonyl-3-aminopropyltriethoxysilane, N-triethoxysilylpropyltriethylenetriamine, N-trimethoxysilylpropyltriethylenetriamine, 10-trimethoxysilyl-1,4,7-triazadecane, 10-triethoxysilyl-1,4,7-triazadecane, 9-Trimethoxysilyl-3,6-diazanonylacetate, 9-Triethoxysilyl-3,6-diazanonylacetate, N-Benzyl-3-aminopropyltrimethoxysilane, N-Benzyl-3-aminopropyltriethoxysilane, N-Phenyl-3-aminopropyltrimethoxysilane, N-Phenyl-3-aminopropyltriethoxysilane, N-Bis(oxyethylene)-3-aminopropyltrimethoxysilane, N-Bis(oxyethylene)-3-aminopropyltriethoxysilane, Ethylene glycol diglycidyl ether, Polyethylene glycol diglycidyl ether, Propylene glycol diglycidyl ether, Tripropylene glycol diglycidyl ether, Polypropylene glycol diglycidyl ether, Neopentyl glycol diglycidyl ether, 1,6-Hexanediol diglycidyl ether, Glycerin diglycidyl ether, 2,2-Dibromo Examples thereof include neopentyl glycol diglycidyl ether, 1,3,5,6-tetraglycidyl-2,4-hexanediol, N,N,N',N'-tetraglycidyl-m-xylenediamine, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenylmethane, etc.

In addition, in order to improve the adhesion between the substrate and the film, and to prevent deterioration of electrical characteristics caused by light irradiation by a backlight, the following phenoplast additives may be added. Specific phenoplast additives are shown below, but are not limited to this structure.

[Chemical formula 30]

When using a compound that improves the adhesion between the substrate and the film, the amount of the compound used is preferably 0.1 to 30 parts by mass, more preferably 1 to 20 parts by mass, per 100 parts by mass of the resin component included in the liquid crystal alignment agent. If the amount used is less than the above value, it becomes difficult to improve the adhesion, and if it exceeds the above value, the liquid crystal alignment may deteriorate.

In addition to the solvents or compounds mentioned above, the liquid crystal alignment agent may also contain a dielectric or conductive material for the purpose of changing the electrical properties of the liquid crystal alignment film, such as the permittivity or conductivity, and further, a crosslinking compound for the purpose of increasing the hardness or density of the film when formed into a liquid crystal alignment film, as long as the effects of the present invention are not impaired.

＜Liquid crystal alignment film/liquid crystal display element＞

After applying the above liquid crystal alignment agent onto a substrate and firing it, if necessary, alignment treatment is performed, and in the case of vertical alignment applications, a liquid crystal alignment film which is one embodiment of the present invention can be obtained without alignment treatment. As the substrate, a highly transparent glass substrate 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, etc. for driving a liquid crystal is formed, from the viewpoint of simplifying the process for manufacturing a liquid crystal display element. In addition, in a reflective liquid crystal display element, an opaque material such as a silicon wafer can be used even if it is used as the substrate on one side, and in this case, a material that reflects light such as aluminum can be used as the electrode. The method for applying the liquid crystal alignment agent is not particularly limited, but industrially, spin coat printing, screen printing, offset printing, flexographic printing, inkjet printing, etc. are common. Other coating methods include dip, roll coater, slit coater, spinner, etc., and these methods can be used depending on the purpose.

The sintering can be carried out at 50°C to 300°C, preferably 80°C to 250°C, by a heating means such as a hot plate. By evaporating the organic solvent in the liquid crystal alignment agent, the coating film can be formed. The thickness of the coating film is preferably 5 nm to 300 nm, more preferably 10 nm to 150 nm, because if it is too thick, the power consumption of the liquid crystal display element tends to increase, and if it is too thin, the reliability of the liquid crystal display element may decrease.

By the above-described method, after obtaining a substrate with a liquid crystal alignment film from the liquid crystal alignment agent, a liquid crystal display element which is one embodiment of the present invention can be obtained by manufacturing a liquid crystal cell by a known method. As an example of a method for manufacturing a liquid crystal cell, a method is provided in which a pair of substrates on which a liquid crystal alignment film is formed are prepared, a spacer is dispersed on the liquid crystal alignment film of one substrate, the liquid crystal alignment film surface is turned inside, the other substrate is bonded, and a liquid crystal is pressure-reduced and injected to seal. Alternatively, a method is provided in which a liquid crystal is dropped on the liquid crystal alignment film surface on which the spacer is dispersed, and then the substrates are bonded to perform sealing. The thickness of the spacer at this time is preferably 1 µm to 30 µm, more preferably 2 µm to 10 µm. The liquid crystal display element manufactured using the above liquid crystal alignment agent has excellent reliability and can therefore be suitably used in large-screen, high-definition liquid crystal TVs.

Example

＜Synthesis of diamine＞

Example 1

Synthesis of ethyl (4-aminobenzyl) glycinate [NG4ABA]

[Chemical Formula 31]

Process 1

In a 1 L four-necked flask equipped with a nitrogen inlet tube and a reflux tube, 105.6 g (0.694 mol) of glycine ethyl hydrochloride, 300 g of THF, and 93.6 g (0.925 mol) of triethylamine were added, and the mixture was stirred at room temperature for 1 hour using a mechanical stirrer, heated at a temperature at which THF refluxes (set to 70°C), 50.0 g (0.231 mol) of 4-nitrobenzyl bromide was dissolved in 500.0 g of THF, and this was slowly added dropwise, and after the dropping was completed, the reaction was allowed to proceed for an additional 24 hours. The reaction was completed when 4-nitrobenzyl bromide disappeared, the precipitated solid was removed by filtration, THF was removed using a rotary evaporator, and 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 solution was added, stirred for 1 hour, the aqueous layer side was recovered, and the aqueous layer was washed three times with 100 g of ethyl acetate. 300 g of ethyl acetate was additionally added to the aqueous layer, potassium carbonate was slowly added, the pH was adjusted to about 10, stirred for 1 hour, the organic phase side was recovered, and washed three times with 100 g of pure water. Anhydrous magnesium sulfate was added to the organic phase, dried, filtered, activated carbon was added, stirred for a short time, the activated carbon was removed by filtration, and the solvent was removed using a rotary evaporator to obtain 46.0 g (0.193 mol) of a pale yellow viscous substance which is the target product (nitro body). The acquisition of the target product was confirmed by ^1H -NMR.

^1H 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)

2nd process

In a 500 ml four-necked flask equipped with a nitrogen inlet tube and a stirrer, 45.0 g (0.19 mol) of the nitro compound obtained above, 300.0 g of THF, and 4.5 g of iron-doped platinum carbon were added, and the inside of the container was carefully replaced with a hydrogen atmosphere, and the reaction was performed at room temperature for 24 hours. The reaction was terminated when the raw material disappeared, the platinum carbon was removed with a membrane filter, and activated carbon (made by Shirasagi) was added to the filtrate, and the mixture was stirred at 40°C for 30 minutes. Thereafter, the mixture was filtered again, the solvent was removed with a rotary evaporator, and then dried with a high vacuum pump to obtain 35.4 g (0.17 mol: yield 89%) of the target product as a pale yellow viscous substance. The acquisition of the target product (NG4ABA) was confirmed by ^1H -NMR.

^1H 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 (4-aminophenethyl) glycinate [NG4APhA]

[Chemical formula 32]

Process 1

In a 1 L four-necked flask equipped with a nitrogen inlet tube and a reflux tube, 50 g (0.246 mol) of 4-nitrophenethylamine hydrochloride, 500 g of THF, and 62.1 g (0.604 mol) of triethylamine were added, and the mixture was stirred at room temperature for 1 hour using a mechanical stirrer, heated at a temperature at which THF refluxes (set to 70°C), 25.1 g (0.205 mol) of ethyl 2-chloroacetate was dissolved in 300 g of THF, and this was slowly added dropwise, and after the dropping was completed, the reaction was allowed to proceed for an additional 24 hours. The reaction was completed when ethyl 2-chloroacetate disappeared (confirmed by HPLC), the precipitated solid was removed by filtration, THF was removed using 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, stirred for 1 hour, the aqueous layer side was recovered, and the aqueous layer was washed three times with 100 g of ethyl acetate. 500 g of ethyl acetate was additionally added to the aqueous layer, potassium carbonate was slowly added, the pH was adjusted to about 10, stirred for 1 hour, the organic phase side was recovered, and washed three times with 100 g of pure water. Anhydrous magnesium sulfate was added to the organic phase, dried, filtered, activated carbon was added, stirred for a short time, the activated carbon was removed by filtration, and the solvent was removed using a rotary evaporator to obtain 34.2 g (0.136 mol: yield 66%) of the target product as a pale yellow viscous substance. The acquisition of the target product (nitro body) was confirmed by ^1H -NMR.

^1H 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)

2nd process

In a 500 ml four-necked flask equipped with a nitrogen inlet tube and a stirrer, 30.0 g of the nitro body obtained above, 300 g of THF, and 3.0 g of iron-doped platinum carbon were added, and the inside of the container was carefully replaced with a hydrogen atmosphere, and the reaction was performed at room temperature for 24 hours. The reaction was terminated when the raw material disappeared, the platinum carbon was removed with a membrane filter, activated carbon (made by Shirasagi) was added to the filtrate, and the mixture was stirred at 40°C for 30 minutes. Thereafter, the mixture was filtered again, the solvent was removed with a rotary evaporator, and then dried with a high vacuum pump to obtain 25.1 g (0.113 mol: yield 95%) of a pale yellow viscous substance which is the target product (NG4APhA). The acquisition of the target product was confirmed by ^1H -NMR.

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)

＜Abbreviations, etc.＞

The abbreviations used in the preparation of liquid crystal alignment agents are as follows.

(Diisocyanate)

IDI: Isophorone diisocyanate

DI-2MG: 1,2-Bis(4-isocyanatophenoxy)ethane

[Chemical formula 33]

(Diamine)

p-PDA: Paraphenylenediamine

NG4ABA: Ethyl (4-aminobenzyl) glycinate

NG4APhA: Ethyl (4-aminophenethyl) glycinate

Me4APhA: N-Methyl-4-aminophenethylamine

DA-3MG: 1,3-di(4-aminophenoxy)propane

APC16: 2-Hexadecyloxy-1,3-diaminobenzene

PCH7: 4-(4-(4-heptylcyclohexyl)phenoxy)benzene-1,3-diamine

[Chemical Formula 34]

(Tetracarboxylic dianhydride)

CBDA: Cyclobutanetetracarboxylic acid dianhydride

(menstruum)

NMP: N-Methyl-2-pyrrolidone

BCS: Butyl Cellosolve

GBL: γ-butyrolactone

Also, the conditions for measuring the molecular weight of polyimide are as follows.

Device: Senshu Kagakusha manufactured room temperature gel permeation chromatography (GPC) device (SSC-7200)

Column: Shodex manufactured column (KD-803, KD-805)

Column temperature: 50℃

Dissolving solution: N,N'-dimethylformamide (as additives, lithium bromide hydrate (LiBr H ₂ O) 30 mmol/L, phosphoric acid anhydrous crystal (o-phosphoric acid) 30 mmol/L, THF 10 ml/L)

Flow rate: 1.0ml/min

Standard samples for calibration curve preparation: TSK standard polyethylene oxide manufactured by Dososa (molecular weights of approximately 9,000,000, 150,000, 100,000, and 30,000), and polyethylene glycol manufactured by Polymer Laboratories (molecular weights of approximately 12,000, 4,000, and 1,000).

＜Synthesis of polymers＞

Example 3

DI-2MG/NG4ABA, APC16

In a 50 ml two-necked flask equipped with a nitrogen inlet tube and a stirrer, 2.00 g (6.75 mmol) of DI-2MG was measured, 19.61 g of NMP was added and dissolved, 0.24 g (0.68 mmol) of APC16 was added, and the mixture was reacted at room temperature for 1 hour. Additionally, 1.22 g (5.88 mmol) of NG4ABA was added, and the mixture was reacted at 40°C for 24 hours in a nitrogen atmosphere. Thereby, a polymer having a concentration of 15 mass% and a viscosity of 220 mPas (polymer solution: P-1) was obtained. The weight average molecular weight of the obtained polymer was Mw: 37200.

Example 4

DI-2MG/NG4APhA, APC16

In a 50 ml two-necked flask equipped with a nitrogen inlet tube and a stirrer, 2.00 g (6.75 mmol) of DI-2MG was measured, 20.12 g of NMP was added and dissolved, 0.24 g (0.68 mmol) of APC16 was added, and the mixture was reacted at room temperature for 1 hour. Additionally, 1.31 g (5.88 mmol) of NG4APhA was added, and the mixture was reacted at 40°C for 24 hours in a nitrogen atmosphere. Thereby, a polymer having a concentration of 15 mass% and a viscosity of 280 mPas (polymer solution: P-2) was obtained. The weight average molecular weight of the obtained polymer was Mw: 39100.

Example 5

DI-2MG/NG4ABA, PCH7

In a 50 ml two-necked flask equipped with a nitrogen inlet tube and a stirrer, 2.00 g (6.75 mmol) of DI-2MG was measured, 20.57 g of NMP was added and dissolved, 0.52 g (1.36 mmol) of PCH7 was added, and the mixture was reacted at room temperature for 1 hour. Additionally, 1.11 g (5.34 mmol) of NG4ABA was added, and the mixture was reacted at 40°C for 24 hours in a nitrogen atmosphere. Thereby, a polymer (polymer solution: P-3) having a concentration of 15 mass% and a viscosity of 230 mPas was obtained. The weight average molecular weight of the obtained polymer was Mw: 40200.

Example 6

IDI, DI-2MG/NG4ABA, PCH7

In a 50 ml two-necked flask equipped with a nitrogen inlet tube and a stirrer, 1.00 g (3.38 mmol) of DI-2MG and 14.05 g of NMP were added and dissolved, 0.37 g (0.97 mmol) of PCH7 was added, and the mixture was reacted at room temperature for 1 hour. Additionally, 0.32 g (1.45 mmol) of IDI and 0.79 g (3.81 mmol) of NG4ABA were added, and the mixture was reacted at 40°C for 24 hours in a nitrogen atmosphere. Thereby, a polymer having a concentration of 15 mass% and a viscosity of 300 mPas (polymer solution: P-4) was obtained. The weight average molecular weight of the obtained polymer was Mw: 44200.

Comparative Example 1

DI-2MG/Me4APhA, APC16

In a 50 ml two-necked flask equipped with a nitrogen inlet tube and a stirrer, 2.00 g (6.75 mmol) of DI-2MG was measured, 17.73 g of NMP was added and dissolved, 0.24 g (0.68 mmol) of APC16 was added, and the mixture was reacted at room temperature for 1 hour. Additionally, 0.89 g (5.94 mmol) of Me4APhA was added, and the mixture was reacted at 40°C for 24 hours in a nitrogen atmosphere. Thereby, a polymer (polymer solution: PRef-1) having a concentration of 15 mass% and a viscosity of 320 mPas was obtained. The weight average molecular weight of the obtained polymer was Mw: 39900.

Comparative Example 2

DI-2MG/Me4APhA, PCH7

In a 50 ml two-necked flask equipped with a nitrogen inlet tube and a stirrer, 2.00 g (6.75 mmol) of DI-2MG was measured, 18.7 g of NMP was added and dissolved, 0.51 g (1.35 mmol) of PCH7 was added, and the mixture was reacted at room temperature for 1 hour. Additionally, 0.79 g (5.27 mmol) of Me4APhA was added, and the mixture was reacted at 40°C for 24 hours in a nitrogen atmosphere. Thereby, a polymer (polymer solution: PRef-2) having a concentration of 15 mass% and a viscosity of 280 mPas was obtained. The weight average molecular weight of the obtained polymer was Mw: 37200.

Comparative Example 3

CBDA/p-PDA, PCH7

In a 50 ml two-necked flask equipped with a nitrogen inlet tube and a stirrer, 1.00 g (9.24 mmol) of p-PDA and 0.88 g (2.31 mmol) of PCH7 were weighed, and 23.12 g of NMP was added and dissolved. Thereafter, 2.20 g (11.20 mmol) of CBDA was added, and the mixture was reacted at room temperature for 24 hours under a nitrogen atmosphere. Thereby, a polymer (polymer solution: PRef-3) having a concentration of 15 mass% and a viscosity of 380 mPas was obtained. The weight average molecular weight of the obtained polymer was Mw: 44200.

＜Preparation of liquid crystal alignment agent＞

Example 7

In a 50 ml Erlenmeyer flask equipped with a stirrer, 10.0 g of the polymer (P-1) obtained in Example 3 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. As a result, a liquid crystal alignment agent (AL-1) having a solid content of 6.0 mass%, NMP of 44 mass%, GBL of 20 mass%, and BCS of 30 mass% was obtained.

Example 8

In a 50 ml Erlenmeyer flask equipped with a stirrer, 10.0 g of the polymer (P-2) obtained in Example 4 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. As a result, a liquid crystal alignment agent (AL-2) having a solid content of 6.0 mass%, NMP of 44 mass%, GBL of 20 mass%, and BCS of 30 mass% was obtained.

Example 9

In a 50 ml Erlenmeyer flask equipped with a stirrer, 10.0 g of the polymer (P-3) obtained in Example 5 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. As a result, a liquid crystal alignment agent (AL-3) having a solid content of 6.0 mass%, NMP of 44 mass%, GBL of 20 mass%, and BCS of 30 mass% was obtained.

Example 10

In a 50 ml Erlenmeyer flask equipped with a stirrer, 10.0 g of the polymer (P-4) obtained in Example 6 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. As a result, a liquid crystal alignment agent (AL-4) having a solid content of 6.0 mass%, NMP of 44 mass%, GBL of 20 mass%, and BCS of 30 mass% was obtained.

Comparative Example 4

In a 50 ml Erlenmeyer flask equipped with a stirrer, 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. As a result, a liquid crystal alignment agent (AL-5) having a solid content of 6.0 mass%, NMP of 44 mass%, GBL of 20 mass%, and BCS of 30 mass% was obtained.

Comparative Example 5

In a 50 ml Erlenmeyer flask equipped with a stirrer, 10.0 g of the polymer (PRef-2) obtained in Comparative Example 2 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. As a result, a liquid crystal alignment agent (AL-6) having a solid content of 6.0 mass%, NMP of 44 mass%, GBL of 20 mass%, and BCS of 30 mass% was obtained.

Comparative Example 6

In a 50 ml Erlenmeyer flask equipped with a stirrer, 10.0 g of the polymer (PRef-3) obtained in Comparative Example 3 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. As a result, a liquid crystal alignment agent (AL-7) having a solid content of 6.0 mass%, NMP of 44 mass%, GBL of 20 mass%, and BCS of 30 mass% was obtained.

The liquid crystal alignment agents (AL-1 to AL-4) of Examples 7 to 10 and the liquid crystal alignment agents (AL-5 to AL-7) of Comparative Examples 4 to 6 were used to evaluate the liquid crystal alignment film according to the following method.

＜Evaluation of whitening resistance and application (printability)＞

One drop of the obtained liquid crystal alignment agent was dropped on each well-cleaned Cr substrate, and the time until it turned white (whitened) was measured while leaving it at room temperature of 25℃ and humidity of 60%. Whitening resistance was evaluated based on the measured time.

After filtering the liquid crystal alignment agent through a 1.0 ㎛ filter, an application test was conducted by flexographic printing on a cleaned Cr substrate using an alignment film printer (“Angstromer” manufactured by Nihon Shashin Insatsu Co., Ltd.).

About 1.0 ml of liquid crystal alignment agent was dropped onto an anilox roll, and after 10 rounds of dry operation, the printer was stopped for 10 minutes to dry the printing plate. Thereafter, printing was performed on one Cr substrate, and the printed substrate was left on a 70°C hot plate for 5 minutes to temporarily dry the coating film, and the film condition was observed. Film thickness unevenness and edge film thickness unevenness were mainly observed with the naked eye and at a magnification of 50 times using an optical microscope (“ECLIPSE ME600” manufactured by Nikon).

＜Evaluation of liquid crystal orientation, voltage retention, and pretilt angle＞

[Observation of liquid crystal orientation and fabrication of liquid crystal cell]

After filtering the liquid crystal alignment agent through a 1.0 ㎛ filter, it was applied to an electrode-attached substrate (a glass substrate measuring 30 mm wide × 40 mm high and 1.1 mm thick; the electrode is a rectangle measuring 10 mm wide × 40 mm long and 35 nm thick ITO electrode) by spin coating printing. After drying on a hot plate at 50°C for 5 minutes, it was baked in an IR oven at 180°C for 20 minutes to form a film with a thickness of 100 nm. After rubbing the film with rayon fabric (YA-20R manufactured by Yoshikawa Kako) (roller diameter: 120 mm, roller rotation speed: 1000 rpm, moving speed: 20 mm/sec, pressing length: 0.4 mm), it was cleaned by irradiating ultrasonic waves in pure water for 1 minute, water droplets were removed by air blowing, and then dried at 80°C for 15 minutes to obtain a substrate with a liquid crystal alignment film attached.

Two substrates with the above liquid crystal alignment film were prepared, a 4 μm spacer was spread on the liquid crystal alignment film surface of one of them, a sealant was printed from thereon, and another substrate was attached with the rubbing direction reversed and the film surfaces facing each other, and the sealant was cured to produce an empty cell. MLC-2041 (manufactured by Merck KGaA) was injected into the empty cell by the reduced pressure injection method, and the injection port was sealed to obtain a liquid crystal cell. Thereafter, after observing the liquid crystal alignment, the liquid crystal cell was heated at 110°C for 1 hour and left at 23°C overnight to obtain a liquid crystal cell for voltage retention measurement.

Using the liquid crystal cell for measuring voltage retention ratio obtained in the above order, a voltage of 1 V was applied for 60 μs at a temperature of 60 °C, the voltage after 166.7 ms was measured, and the degree of voltage retention ratio was calculated. In addition, a VHR-1 voltage retention ratio measuring device manufactured by Toyo Technica was used for measuring the voltage retention ratio.

[Evaluation of pretilt angle]

The pretilt angle was measured using an Axo Scan Muller matrix polarimeter manufactured by Optometrics.

The results of the various evaluations mentioned above are shown in Table 3.

[Table 3]

The liquid crystal alignment agents of Examples 7 to 10 have excellent whitening resistance and good printability compared to the comparative examples. Since Comparative Example 6 is a polyamic acid-based material, it is a material system with good whitening resistance and printability. It is expected that Examples 7 to 10 can obtain characteristics equivalent to or higher than those of Comparative Example 5 in terms of whitening resistance and printability.

In addition, in the liquid crystal cells obtained by using the liquid crystal alignment agents of Examples 7 to 10, a high pretilt angle and a high voltage retention rate were obtained. For example, since the side chain-containing monomer used in this Example contributes to increasing the pretilt angle of the liquid crystal, it is expected that the target pretilt angle can be obtained by variously selecting the structure or introduction amount of the side chain-containing monomer. It is thought that the liquid crystal alignment film which is one embodiment of the present invention is very promising as a liquid crystal alignment film obtainable by low-temperature firing. In addition, the liquid crystal alignment film and the liquid crystal display element could be suitably obtained by using any of the liquid crystal alignment agents of Examples 7 to 10.

Industrial applicability

A liquid crystal display element manufactured using the liquid crystal alignment agent of the present invention can be a highly reliable liquid crystal display device, and can be suitably used for display elements of various types, such as a TN liquid crystal display element, an STN liquid crystal display element, a TFT liquid crystal display element, a VA liquid crystal display element, and an OCB liquid crystal display element.

Claims (10)

A liquid crystal alignment agent using a polymer obtained from a diamine derivative represented by the following formula (1), a diisocyanate derivative, and a monomer selected from a diamine or diisocyanate having a specific side chain, wherein the monomer containing the specific side chain is represented by the following formula (2):
[Chemical Formula 1]

In the formula, A represents a divalent organic group selected from an aliphatic hydrocarbon group or an aromatic hydrocarbon group, 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, which 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), and Ra and Rb each independently represent a hydrogen atom or an aliphatic hydrocarbon group having 1 to 2 carbon atoms.
[Chemical formula 2]

In the formula, N represents an amino group or an isocyanate group, R ₃ represents a single bond or a divalent organic group, X ¹ , X ² , and X ³ each independently represent a benzene ring or a cyclohexane ring, p, q, and r each independently represent an integer of 0 or 1, and R ₄ represents a hydrogen atom, an alkyl group having 1 to 22 carbon atoms, or a divalent organic group having 12 to 25 carbon atoms and a steroid skeleton. delete In the first paragraph,
A liquid crystal alignment agent, wherein the above diamine derivative is a diamino compound represented by the following formula (3):
[Chemical Formula 3]

In the formula, Ar represents an aryl group, D represents a single bond or a hydrocarbon group having 1 to 5 carbon atoms, and R ₁ , R ₂ , Ra and Rb are synonymous with R ₁ , R ₂ , Ra and Rb above. In the third paragraph,
The above diamine derivative is a liquid crystal alignment agent, which is a diamino compound represented by the following formula (3-a):
[Chemical Formula 4]

In the formula, D and R ₁ are synonymous with D and R ₁ above. A polymer obtained from a diamino compound represented by the following formula (3-1), a diisocyanate derivative, and a monomer selected from a diamine or diisocyanate having a specific side chain, wherein the monomer containing the specific side chain is represented by the following formula (2):
[Chemical Formula 5]

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

In the formula, N represents an amino group or an isocyanate group, R ₃ represents a single bond or a divalent organic group, X ¹ , X ² , and X ³ each independently represent a benzene ring or a cyclohexane ring, p, q, and r each independently represent an integer of 0 or 1, and R ₄ represents a hydrogen atom, an alkyl group having 1 to 22 carbon atoms, or a divalent organic group having 12 to 25 carbon atoms and a steroid skeleton. delete In paragraph 5,
A polymer wherein the above diisocyanate derivative has at least one of the structures represented by the following formulae (4-1) to (4-13):
[Chemical formula 7]

In the formula, R ₅ and R ₆ each independently represent an aliphatic hydrocarbon group having 1 to 10 carbon atoms. A liquid crystal alignment agent using the polymer described in claim 5 or claim 7. A liquid crystal alignment film obtained from a liquid crystal alignment agent using a liquid crystal alignment agent according to any one of claims 1, 3 and 4, or a polymer according to claim 5 or 7. A liquid crystal display element using the liquid crystal alignment film described in Article 9.