TW201805334A - Liquid crystal alignment agent, liquid crystal alignment membrane, and liquid crystal display element using same - Google Patents

Abstract

The present invention provides a liquid crystal display element comprising a liquid crystal alignment membrane capable of being fired at a low temperature and having good printability of a liquid crystal alignment agent (solubility of a polymer in a solvent), as well as good liquid crystal alignment and a good voltage retention rate, and also provides a liquid crystal alignment agent for forming said liquid crystal alignment membrane. The present invention relates to a liquid crystal alignment agent containing a polymer obtained by reacting at least one hydrazide derivative selected from the group consisting of formulas (1)-(3) with at least one compound selected from formulas (4) and (5) (in the formulas, W, X, and Z each independently represent a bivalent organic group, and Z represents a single bond or a bivalent organic group).

Description

Liquid crystal alignment agent, liquid crystal alignment film, and liquid crystal display element using the same

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

In a liquid crystal display device, a liquid crystal alignment film plays a role of aligning liquid crystals in a certain direction. At present, the main liquid crystal alignment film used in the industry is a polyimide system formed by using a polyamidate precursor (also referred to as a polyamic acid) or a solution of polyimide. A liquid crystal alignment agent is applied to a substrate and formed into a film. In addition, when the liquid crystals are aligned in parallel or inclined on the substrate surface, a surface stretching treatment by rubbing is performed after film formation. In addition, as an alternative to the rubbing treatment, there is also a proposal to use an anisotropic photochemical reaction by irradiation of polarized ultraviolet rays or the like, and in recent years, industrialization has been discussed.

In order to improve the display characteristics of a liquid crystal display device, the structure of polyamic acid or polyimide is variously changed, optimized, or resins with different characteristics are blended, or additives are added to align the liquid crystal. It is possible to improve the performance, control of the pretilt angle, and the improvement of electrical characteristics, etc., and further improve the display characteristics. Many technologies have been proposed. For example, in Japanese Patent Application Laid-Open No. 2-287324, To a high voltage holding ratio, a polyimide resin having a specific repeating structure is used. In Japanese Patent Application Laid-Open No. 10-104633, it is proposed to reduce the time until the afterimage disappears by using a soluble polyfluoreneimide having a nitrogen atom in addition to the fluorenimine group for the afterimage phenomenon.

On the other hand, in recent years, research and development of flexible displays and the like have been conducted, and a resin substrate or the like is used for the substrate, and a liquid crystal alignment film capable of low-temperature firing has been required along with this. Because soluble polyfluorene imine is preliminarily imidized and does not require the thermal curing step of heating the imidization, it can be fired at a relatively low temperature, but the solubility in the solvent is insufficient, and printing defects are prone to occur. . Therefore, it is necessary to develop a material that can be fired at a low temperature, has good solvent solubility, and has the reliability as an alignment film.

[Prior technical literature] [Patent Literature]

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

[Patent Document 2] Japanese Unexamined Patent Publication No. 7-287324

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

[Patent Document 2] International Publication WO2006 / 126555

In recent years, with the multi-functionalization and diversification of liquid crystal displays, the manufacturing of liquid crystal panels using glass substrates has progressed to the development of flexible displays using plastic substrates, that is, thin film substrates. Accordingly, need A liquid crystal alignment film that can be fired at a low temperature of 180 ° C or lower, and also requires reliability (high voltage retention rate or low residual DC voltage, etc.) required by conventional alignment films.

Examples of the material used for the liquid crystal alignment film include polyimide precursors such as polyamic acid or polyamic acid esters, or polyimide obtained by dehydrating them by firing or chemical reaction. . Polyamic acid has the characteristics of being easy to synthesize and having excellent solubility, and is excellent in coating / film-forming properties to a substrate. However, it is easy to decompose due to hydrolysis or the like on the structure, which has a problem in long-term reliability. On the other hand, the solvent-soluble polyimide obtained by the dehydration reaction of polyamic acid includes the advantages of excellent chemical stability / heat resistance and excellent long-term reliability, but the lack of solubility Due to its solvent selectivity, precipitation and the like occur during coating / film formation, and defects are liable to occur in the coating film.

With the enlargement, high definition, and diversification of the use of LCD panels, the exploration of ways to solve their problems is an urgent task.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a liquid crystal that can be fired at a low temperature and has good printability (solubility of a polymer in a solvent) of a liquid crystal alignment agent, and good liquid crystal alignment and voltage retention. Liquid crystal display element of alignment film, and liquid crystal alignment agent for forming the liquid crystal alignment film.

The inventors conducted intensive studies and found that a liquid crystal alignment system using a polymer having a novel structure is extremely effective With the stated purpose, the present invention has finally been completed. The single system for obtaining a novel polymer contains a part of novel compounds not described in the literature.

That is, this invention has the following summary.

A liquid crystal alignment agent comprising a hydrazine derivative selected from at least one selected from the group consisting of the following formulae (1) to (3) and a formula selected from the following formula (4) and the following formula ( 5) a polymer obtained by reacting at least one compound;

In the above formula, W, X, and Z each independently represent a divalent organic group, and Z represents a single bond or a divalent organic group.

According to the present invention, it is possible to provide a polymer for a liquid crystal alignment agent that can obtain a high-quality film at low temperature and is excellent in printability. Furthermore, it can provide an alignment film with excellent liquid crystal alignment properties in addition to this characteristic. High VHR liquid crystal alignment film.

[Mode for Carrying Out the Invention]

The liquid crystal alignment agent of the present invention contains Compounds of at least one of the groups (1) to (3) (also known as hydrazine derivatives) and compounds selected from the following formula (4) (also known as tetracarboxylic dianhydrides) and the following A liquid crystal alignment agent for a polymer obtained by reacting at least one compound of a compound of the formula (5) (also referred to as a diisocyanate).

Hereinafter, each constituent element will be described in detail.

<Dihydrazine derivative>

In order to obtain the polymer contained in the liquid crystal alignment agent of the present invention, the hydrazine derivative used is represented by the following formulae (1) to (3).

In the formula, Z represents a single bond or a divalent organic group. The structure system of the divalent organic group is not particularly limited. In consideration of various characteristics to be achieved by a liquid crystal alignment film containing a polymer obtained from a dihydrazine derivative, various structures corresponding to the characteristics are selected. Although specific examples are given, the following structures may be mentioned, but they are not limited to these.

/ In the formula represents a bonding point with other atoms in the formula (1) and the formula (3).

Dihydrazine can be derived from halides or esters of dicarboxylic acids, but from the viewpoint of availability or ease of handling, Z1, Z3, Z5, and Z6 are particularly preferred.

Specifically, the following compounds are preferred.

In the polymer contained in the liquid crystal alignment agent of the present invention, the hydrazine derivative represented by the formulae (1) to (3) is preferably in a range of 0 to 90 mol%, and more preferably in a range of 10 to 80 mol%. It is particularly preferable to use it in a range of 20 to 70 mol%.

<Tetracarboxylic dianhydride>

In order to obtain the polymer contained in the liquid crystal alignment agent of the present invention, the tetracarboxylic dianhydride used as appropriate is represented by the following formula (4).

In the formula, W is a divalent organic group, and the structure is not particularly limited, and a polymer capable of stably polymerizing can be suitably used.

Specific examples of tetracarboxylic dianhydride are given below.

Examples of the tetracarboxylic dianhydride having an alicyclic structure or an aliphatic structure include 1,2,3,4-cyclobutane tetracarboxylic dianhydride and 1,2-dimethyl-1,2,3 1,4-cyclobutane tetracarboxylic dianhydride, 1,3-dimethyl-1,2,3,4-cyclobutane tetracarboxylic dianhydride, 1,2,3,4-tetramethyl-1 , 2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 2,3,4,5-tetrahydrofurantetracarboxylic dianhydride, 1, 2,4,5-cyclohexanetetracarboxylic dianhydride, 3,4-dicarboxy-1-cyclohexyl succinic dianhydride, 3,4-dicarboxy-1,2,3,4-tetrahydro-1 -Naphthalenesuccinic dianhydride, 1,2,3,4-butanetetracarboxylic dianhydride, bicyclo [3,3,0] octane-2,4,6,8-tetracarboxylic dianhydride, 3, 3 ', 4,4'-Dicyclohexyltetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentylacetic dianhydride, cis-3,7-dibutylcyclooctane-1,5-di Ene-1,2,5,6-tetracarboxylic dianhydride, tricyclo [4.2.1.02,5] nonane-3,4,7,8-tetracarboxylic acid-3,4: 7,8-di Anhydride, hexacyclo [6.6.0.12,7.03,6.19,14.010,13] hexadecane-4,5,11,12-tetracarboxylic acid-4,5: 11,12-dianhydride, 4- (2,5 -Dioxotetrahydrofuran-3-yl) -1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic anhydride and the like.

Furthermore, in addition to the tetracarboxylic dianhydride having an alicyclic structure or an aliphatic structure, if an aromatic tetracarboxylic dianhydride is used, it is more suitable because the liquid crystal alignment is increased and the accumulated charge of the liquid crystal cell can be reduced. . Examples of the aromatic tetracarboxylic dianhydride include pyromellitic dianhydride, 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, 2,2', 3,3'-biphenyltetrahydride Carboxylic dianhydride, 2,3,3 ', 4-biphenyltetracarboxylic dianhydride, 3,3', 4,4'-diphenylketone tetracarboxylic dianhydride, 2,3,3 ', 4 -Diphenyl ketone tetracarboxylic dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, bis (3,4-dicarboxyphenyl) fluorene dianhydride, 1,2,5,6-naphthalene Tetracarboxylic dianhydride, 2,3,6,7-naphthalene tetracarboxylic dianhydride, etc.

The tetracarboxylic dianhydride system can be used in combination of 1 type or more according to characteristics such as liquid crystal alignment, voltage holding characteristics, and accumulated charge when the liquid crystal alignment film is used.

From the viewpoints of solubility, liquid crystal alignment characteristics, and the like, the tetracarboxylic dianhydride is preferably any one or two or more compounds of the following formulae (2-1) to (2-8).

In the polymer contained in the liquid crystal alignment agent of the present invention, the compound of formula (4) is preferably in a range of 0 to 90 mol%, more preferably in a range of 10 to 80 mol%, and even more preferably 30 to 50 mol%. Ranges are combined.

<Diisocyanate>

In order to obtain the polymer contained in the liquid crystal alignment agent of the present invention, the diisocyanate used as appropriate is represented by the following formula (5).

[Chemical 7] OCN-X-NCO (5)

In the formula, the X-based divalent organic group is not particularly limited in its structural system, and can be used in accordance with availability and the like. An example of a preferable specific structure is shown below.

In the formula, R ₂ and R ₃ represent an aliphatic hydrocarbon having 1 to 10 carbon atoms.

Although the aliphatic diisocyanates represented by the aforementioned formulae (3-1) to (3-5) have poor reactivity, they have the advantage of improving the solubility of solvents, as shown in formulae (3-6) and (3-7) Aromatic diisocyanate is rich in reactivity and has the effect of improving heat resistance, but it has the disadvantage of lowering the solubility of the solvent. Among the versatility or characteristics, particularly preferred are diisocyanates represented by the formulae (3-1), (3-7), (3-8), (3-9), and (3-10). From the viewpoint, particularly preferred is a diisocyanate of formula (3-12), and from the viewpoint of liquid crystal alignment, particularly preferred is a diisocyanate of formula (3-13). The diisocyanate may be used in combination of two or more kinds, and various applications are preferably performed according to the characteristics to be obtained.

In the polymer contained in the liquid crystal alignment agent of the present invention, the compound of formula (5) is preferably in a range of 10 to 100 mol%, more preferably in a range of 20 to 90 mol%, and even more preferably 50 to 70 mol%. The ranges are used in combination.

<Diamine>

The polymer of the present invention can be obtained by reacting at least one compound selected from the formulae (1) to (3) and at least one compound selected from the formulae (4) and (5). However, a part of the dihydrazine derivative may be replaced with a compound (diamine) represented by the following formula (6) and used in combination. Diamines are abundant, and there are many compounds containing organic groups with various functional groups. When the above-mentioned polymers have functions that are difficult to exhibit, they behave better.

In the formula, Y is a divalent organic group, and specific structural examples thereof can be listed as the following formulae (Y-1) to (Y-175), but are not limited thereto.

In the formula, R ₄ each independently represents a hydrogen atom, a methyl group, or an ethyl group.

In the reaction between the tetracarboxylic dianhydride of the above formula (4) and the diamine represented by the above formula (6), polyamidic acid is given, and in the reaction between the diisocyanate and the diamine, polyurea is given.

In the formula, n is an integer of 1 to 6 unless specifically mentioned.

In the formula, n is an integer of 1 to 6.

<Polymer>

The polymer used in the present invention has a structural unit selected from at least one of P1 and P2 described below.

The formula [P1] [P3] is a structure obtained when a tetracarboxylic dianhydride is reacted with a dihydrazine derivative, and the formula [P2] [P4] is a structure obtained when a diisocyanate is reacted with a dihydrazine derivative. .

In the formula, A is a divalent organic group derived from a dihydrazine derivative, B represents a divalent organic group derived from a tetracarboxylic dianhydride, and D represents a structure of a divalent organic group derived from a diisocyanate.

This structural unit system has very high hydrogen bonding, and since the strength of the bonding group is also high, it is possible to increase the strength of the film when it becomes a film. That is, a high-quality film can be obtained by simply removing the solvent, so that it can be fired at a low temperature.

In addition, the structural unit of [P1] [P3] has a carboxylic acid. Since it has a highly polar structure, it can be easily dissolved in general high-boiling solvents such as NMP and γ-butyrolactone, which can suppress the coating and film formation of the agent. Precipitation or agglomeration of the polymer.

The polymer used in the present invention may be a polymer having only at least one structural unit [P1], [P2], [P3], [P4], or may have a polymer selected from structural units [P1], [P2 ], [P3], [P4] more than two structures In order to obtain better characteristics, the polymer is preferably the latter.

When the polymer used in the present invention is a polymer having two or more structures selected from the structural units [P1], [P2], [P3], and [P4] (such polymers will also be referred to as hereinafter Copolymer), the copolymerization ratio is not particularly limited, but with respect to the overall structural unit of the copolymer, as the ratio of the structural units of [P1] and [P3] becomes larger, the solubility can be improved. The ratio of the structural units becomes larger, and the heat resistance and mechanical strength increase. It is preferably [P1] + [P3]: [P2] + [P4] = 10: 90 ~ 90: 10, more preferably between 30: 70 ~ 70: 30.

The structural unit of P1 can cyclize a carboxylic acid residue by a condensation reaction similar to that of polyamic acid. Thereby, it was judged that heat resistance or mechanical strength can be further improved. On the other hand, since the solubility of the solvent decreases due to the disappearance of the carboxylic acid residue, the condensation ratio is preferably about 0% to 70%, but it is not particularly limited.

On the other hand, when a diamine is used, from the viewpoint of the balance of various characteristics, a preferable introduction ratio is 0% to 90% with respect to the entire structural unit of the polymer.

<Organic solvent>

The organic solvent used in the reaction for obtaining the polymer of the present invention is not particularly limited as long as it dissolves the produced polymer. Specific examples are given below.

Examples include N, N-dimethylformamidine, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-formyl Kiji Lactam, dimethylarsine, tetramethylurea, pyridine, dimethylarsine, hexamethylarsine, γ-butyrolactone, isopropanol, methoxymethylpentanol, dipentene, ethyl Methylpentyl ketone, methyl nonyl ketone, methyl ethyl ketone, methyl isoamyl ketone, methyl isopropyl ketone, methyl cellosolve, ethyl cellosolve, methyl cellosolve acetic acid Ester, ethyl cellosolve 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 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 monoethyl ether Ester monopropyl ether, 3-methyl-3-methoxybutyl acetate, tripropylene glycol methyl ether, 3-methyl-3-methoxybutanol, diisopropyl ether, ethyl Isobutyl ether, diisobutylene, pentyl acetate, butyl Butyl acid, butyl ether, diisobutyl ketone, methyl cyclohexene, propyl ether, dihexyl ether, dioxane, n-hexane, n-pentane, n-octane, diethyl ether, cyclohexanone, Ethyl carbonate, propyl carbonate, methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, n-butyl acetate, propylene glycol monoethyl ether, methyl pyruvate, ethyl pyruvate, 3- Methyl methoxypropionate, methyl ethyl 3-ethoxypropionate, ethyl ethyl 3-methoxypropionate, 3-ethoxypropionic acid, 3-methoxypropionic acid, 3-methoxy Propyl propionate, butyl 3-methoxypropionate, diglyme, 4-hydroxy-4-methyl-2-pentanone, 3-methoxy-N, N-dimethyl Propamide, 3-ethoxy-N, N-dimethylpropanamide, 3-butoxy-N, N-dimethylpropanamide and the like. These systems can be used alone or in combination. Furthermore, even for polymers that do not dissolve The solvent may be used by mixing with the above-mentioned solvent within a range in which the produced polymer does not precipitate.

In addition, since the water in the organic solvent hinders the polymerization reaction and causes the polymer to be hydrolyzed, the organic solvent is preferably one that has been dehydrated and dried as much as possible.

When the tetracarboxylic dianhydride is reacted with a diamine component in an organic solvent, a solution in which the diamine component is dispersed or dissolved in the organic solvent is stirred, and the tetracarboxylic dianhydride is directly or dispersed or dissolved in A method of adding in an organic solvent, a method of adding a diamine component to a solution in which a tetracarboxylic dianhydride is dispersed or dissolved in an organic solvent, a method of adding a tetracarboxylic dianhydride and a diamine component alternately, etc. , You can use any of these methods. In addition, when the tetracarboxylic dianhydride or diamine component is composed of a plurality of types of compounds, they can be reacted in a pre-mixed state, or they can be individually and sequentially reacted, and the individual reaction can be reduced. The molecular weight body undergoes a mixing reaction to become a high molecular weight body.

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. The reaction system can be carried out at any concentration, but 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 stir uniformly. Therefore, tetracarboxylic dianhydride and The total concentration of the diamine component in the reaction solution is preferably 1 to 50% by mass, and more preferably 5 to 30% by mass. The reaction can be performed at a high concentration at the beginning of the reaction, and then an organic solvent can be added.

In the polymerization reaction of polyamic acid, the total molar number of the tetracarboxylic dianhydride and the total molar number of the diamine component is preferably 0.8 to 1.2. As with the usual polycondensation reaction, the closer this Mohr ratio is to 1.0, the larger the molecular weight of the polyamidate produced.

The polyimide of the present invention is a polyimide obtained by dehydrating and closing the polyamic acid ring, which is suitable as a polymer for obtaining a liquid crystal alignment film.

In the polyfluorene imine of the present invention, the dehydration ring closure rate (fluorene imidization rate) of the amino acid group is not necessarily 100%, and can be arbitrarily adjusted according to the use or purpose.

[Polymer hydrazine]

The polymer used in the present invention can be imidized by dehydration and ring closure similar to that of polyamidic acid. Examples of the method for the imidization of the polymer of the present invention include thermal imidization by directly heating a solution of the polymer, and adding a catalyst of the imidization to the solution of the polymer.

The temperature when the polymer of the present invention is thermally fluorinated in the solution is 100 ° C to 400 ° C, preferably 120 ° C to 250 ° C, and it is preferable to remove the water generated by the hydration reaction to the system. Outside.

The catalyst / imidization of the polymer of the present invention can be carried out by adding a basic catalyst and an acid anhydride to their solutions, and stirring at -20 to 250 ° C, preferably 0 to 180 ° C. The amount of the basic catalyst is 0.5 to 30 mol times, preferably 2 to 20 mol times, of the fluorenyl hydrazino acid group and the sulfamic acid group of the aforementioned formula [P1] [P3]. The amount of the acid anhydride is the foregoing The fluorenyl hydrazinoic acid group and the sulfamic acid group of the formula [P1] [P3] are 1 to 50 mol times, preferably 3 to 30 mol times. Examples of the basic catalyst include pyridine, triethylamine, trimethylamine, and trimethylamine. Butylamine, trioctylamine and the like, among them, pyridine is more suitable because it has a moderate basicity for the reaction to proceed. Examples of the acid anhydride include acetic anhydride, trimellitic anhydride, pyromellitic anhydride, and the like. When acetic anhydride is used, purification after the reaction is facilitated and is preferred. The rate of ammonium imidization caused by catalyst ammonium imidization can be controlled by adjusting the amount of catalyst, reaction temperature, and reaction time.

[Recycling of polymers]

When recovering the fluorene imidized polymer produced from the reaction solution of the polymer of the present invention, the reaction solution may be put into a weak solvent to cause precipitation. Examples of the weak solvent used for precipitation include methanol, acetone, hexane, butyl cellosolve, heptane, methyl ethyl ketone, methyl isobutyl ketone, ethanol, toluene, benzene, and water. The polymer precipitated after being put into a weak solvent can be filtered and recovered, and can be dried at room temperature or under heat or pressure. In addition, the polymer recovered by precipitation is re-dissolved in an organic solvent, and the operation of re-precipitation recovery is repeated 2 to 10 times, thereby reducing impurities in the polymer. Examples of the weak solvent at this time include alcohols, ketones, hydrocarbons, and the like. If three or more types of weak solvents selected from these are used, the efficiency of purification is further increased and is more suitable.

The molecular weight of the polymer contained in the liquid crystal alignment agent of the present invention is measured by GPC (Gel Permeation Chromatography) method when considering the strength of the coating film obtained from the polymer, the workability during coating film formation, and the uniformity of the coating film. The weight average molecular weight is preferably 5,000 to 1,000,000, and more preferably 10,000 to 150,000.

<Liquid crystal alignment agent>

The liquid crystal alignment agent of the present invention is a coating liquid for forming a liquid crystal alignment film, and is a solution in which a resin component for forming a resin film is dissolved in an organic solvent. Here, the aforementioned resin component is a resin component including at least one polymer selected from the polymer of the present invention. At this time, the content of the resin component is preferably 2% by mass to 20% by mass, more preferably 3% by mass to 15% by mass, and particularly preferably 3 to 10% by mass.

In the present invention, all of the resin components may be copolymers used in the present invention, or other polymers may be mixed with the polymer of the present invention. At this time, the content of the polymer other than the polymer of the present invention in the resin component is 0.5 to 15% by mass, and preferably 1 to 10% by mass.

Examples of such other polymers include acrylic polymers, methacrylic polymers, novolac resins, polyhydroxystyrene, polyimide precursors, polyimides, polyimides, polyesters, and celluloses. , Polysiloxane, etc.

The organic solvent used for the liquid crystal alignment agent of the present invention is not particularly limited as long as it is an organic solvent that dissolves a resin component. Specific examples are given below.

Examples include N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methylcaprolactam, 2-pyrrolidone , N-ethylpyrrolidone, N-vinylpyrrolidone, dimethylarsine, tetramethylurea, pyridine, dimethylarsine, hexamethylarsine, γ-butyrolactone, 3-methoxy -N, N-dimethylpropanamide, 3-ethoxy-N, N-dimethylpropanamide, 3-butoxy -N, N-dimethylpropanamine, 1,3-dimethyl-imidazolinone, ethylpentyl ketone, methyl nonyl ketone, methyl ethyl ketone, methyl isoamyl ketone, Methyl isopropyl ketone, cyclohexanone, ethyl acetate, propylene carbonate, diglyme, 4-hydroxy-4-methyl-2-pentanone, and the like. These systems can be used alone or in combination.

The liquid crystal alignment agent of this invention may contain components other than the above. Examples thereof include a solvent or a compound that increases film thickness uniformity or surface smoothness when a liquid crystal alignment agent is applied, and a compound that increases adhesion between a liquid crystal alignment film and a substrate.

Specific examples of the solvent (weak solvent) that increases the uniformity of the film thickness or the surface smoothness include the following.

Examples include isopropanol, methoxymethylpentanol, methyl cellosolve, ethyl cellosolve, butyl cellosolve, methyl cellosolve acetate, and 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 third 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 monoacetic acid Ester monopropyl ether, 3-methyl-3-methoxybutyl acetate, tripropylene glycol methyl ether, 3-methyl-3-methoxybutanol, diisopropyl ether, ethyl isopropyl Butyl ether, diisobutylene, pentyl acetate, butyl butyrate, butyl ether, diisobutyl ketone, methylcyclohexene, propyl ether, dihexyl ether, 1-hexane Alcohol, 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 ethyl 3-methoxypropionate, 3-ethoxypropionic acid, 3-methoxy Propanoic 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-mono Ethyl ether-2-acetate, dipropylene glycol, 2- (2-ethoxypropoxy) propanol, methyl lactate, ethyl lactate, n-propyl lactate, n-butyl lactate, isoamyl lactate Wait for a solvent with a low surface tension.

These weak solvents may be used alone or in combination of plural types. When the solvent described above is used, it is preferably 5 to 80% by mass, and more preferably 20 to 60% by mass, of the entire solvent contained in the liquid crystal alignment agent.

Examples of the compound that increases the uniformity or surface smoothness of the film thickness include fluorine-based surfactants, polysiloxane-based surfactants, and non-ionic surfactants.

More specific examples include Eftop EF301, EF303, EF352 (manufactured by Tochem Products Co., Ltd.), Megafac F171, F173, R-30 (manufactured by Dainippon Ink Chemical Industry Co., Ltd.), Florad FC430, FC431 ( (Made by Sumitomo 3M Co., Ltd.), Ashai Guard AG710, Surflon S-382, SC101, SC102, SC103, SC104, SC105, SC106 (Asahi Glass Co., Ltd. Company system) and so on. 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 with respect to 100 parts by mass of the resin component contained in the liquid crystal alignment agent.

Specific examples of the compound that increases the adhesion between the liquid crystal alignment film and the substrate include a functional silane-containing compound or an epoxy-containing compound and the like shown below.

Examples include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 2-aminopropyltrimethoxysilane, 2-aminopropyltriethoxysilane N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, 3- Ureapropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, N-ethoxycarbonyl-3-aminopropyltrimethoxysilane, N-ethoxycarbonyl-3-amine Propyltriethoxysilane, N-triethoxysilylpropyltriethylenetriamine, N-trimethoxysilylpropyltriethylenetriamine, 10-trimethoxysilyl-1 , 4,7-triazadecane, 10-triethoxysilyl-1,4,7-triazadecane, 9-trimethoxysilyl-3,6-diazanonylethyl Acid ester, 9-triethoxysilyl-3,6-diazanonyl acetate, N-benzyl-3-aminopropyltrimethoxysilane, N-benzyl-3-amino Propyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltriethoxysilane, N-bis (oxyethylene) -3 -Aminopropyltrimethoxysilane, N-bis (oxyethylene) -3-aminopropyltriamine Ethoxysilane, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether Ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerin diglycidyl ether, 2,2-dibromo neopentyl glycol diglycidyl ether, 1,3,5,6-tetraglycidyl-2,4-hexanediol, N, N, N ', N',- Tetraglycidyl-m-xylylenediamine, 1,3-bis (N, N-glycidylaminomethyl) cyclohexane, N, N, N ', N',-tetraglycidyl -4,4'-diaminodiphenylmethane and the like.

Furthermore, in addition to improving the adhesion between the substrate and the film, and for the purpose of preventing a decrease in electrical characteristics due to the backlight, the following phenolic plastic additives may be introduced. Specific phenolic plastic additives are shown below, but are not limited to this structure.

When a compound that improves the adhesion to the substrate is used, the amount used is preferably from 0.1 to 30 parts by mass, more preferably from 1 to 20 parts by mass, relative to 100 parts by mass of the resin component contained in the liquid crystal alignment agent. If make When the amount is less than 0.1 parts by mass, the effect of improving the adhesion cannot be expected, and if it is more than 30 parts by mass, the alignment of the liquid crystal may be deteriorated.

In the liquid crystal alignment agent of the present invention, in addition to the above, as long as the effect of the present invention is not impaired, the purpose is to change the electrical properties such as the permittivity and conductivity of the liquid crystal alignment film, and a dielectric may be added. Or a conductive material, and a crosslinkable compound for the purpose of increasing the hardness or density of the film when it becomes a liquid crystal alignment film.

<Liquid crystal alignment film / liquid crystal display element>

The liquid crystal alignment agent of the present invention can be used as a liquid crystal alignment film after being coated and fired on a substrate, and then subjected to alignment treatment by rubbing treatment or light irradiation, or without alignment treatment in vertical alignment applications. At this time, the substrate used is not particularly limited as long as it is a substrate having high transparency, and a glass substrate, a plastic substrate such as an acrylic substrate, or a polycarbonate substrate can be used. In addition, it is preferable to use a substrate on which an ITO electrode for liquid crystal driving is formed from the viewpoint of simplification of the manufacturing process. Moreover, in a reflective liquid crystal display element, if the substrate is only one side, an opaque material such as a silicon wafer may be used, and an electrode at this time may also use a material that reflects light.

The method for applying the liquid crystal alignment agent is not particularly limited, but the method is generally industrially performed by screen printing, lithographic printing, flexographic printing, inkjet, or the like. Other coating methods include dipping, roll coating, slit coating, spin coating, and the like, and these can be used according to the purpose.

The firing after coating the liquid crystal alignment agent on the substrate is possible. A heating means such as a hot plate is performed at 50 to 300 ° C, preferably 80 to 250 ° C, and the solvent is evaporated to form a coating film. If the thickness of the coating film formed after firing is too thick, it is disadvantageous in terms of 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 to 300 nm. , More preferably 10 to 150 nm. When the liquid crystal is aligned horizontally or obliquely, the baked coating film is treated with rubbing or polarized ultraviolet radiation.

The liquid crystal display element of the present invention obtains a substrate with a liquid crystal alignment film from the liquid crystal alignment agent of the present invention by the method described above, and then produces a liquid crystal cell by a well-known method to become a liquid crystal display element.

As an example of the production of liquid crystal cells, a pair of substrates having a liquid crystal alignment film formed thereon can be exemplified. Spacers are spread on the liquid crystal alignment film of one of the substrates, and the liquid crystal alignment film surface becomes the inner side, and the other is bonded. A method of sealing the substrate by injecting liquid crystal under reduced pressure, or a method of sealing the substrate by bonding the substrate after dropping the liquid crystal on the liquid crystal alignment film surface on which the spacers are dispersed. The thickness of the spacer at this time is preferably 1 to 30 μm, and more preferably 2 to 10 μm.

As described above, the liquid crystal display device produced using the liquid crystal alignment agent of the present invention is excellent in reliability, and can be suitably used for large-screen and high-definition liquid crystal televisions.

[Example] <Synthesis of liquid crystal alignment agent>

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

(Acid dianhydride)

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

BODA: Bicyclic [3,3,0] octane-2,4,6,8-tetracarboxylic dianhydride

TCA: 2,3,5-tricarboxycyclopentylacetic acid-1,4,2,3-dianhydride

(Diisocyanate)

IDI: isophorone diisocyanate

O-TolDI: toluene diisocyanate

4IBI: (isocyanatomethyl) phenyl-isocyanate

(Dihydrazine derivative)

OXDHyd: oxadiazine dihydrazine

C4DHyd: hexamethylene dihydrazide

mPhDhyd: m-phenylene dihydrazide

4APhDHyd: 4-Aminophenylhydrazine

(Diamine)

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

PCH7AB: 4- (4- (4-heptylcyclohexyl) phenoxy) benzene-1,3-diamine

<Solvent>

NMP: N-methyl-2-pyrrolidone

BCS: Butyl Cellosolve

The molecular weight measurement conditions of polyimide are as follows.

Device: SENSHU Scientific Normal Temperature Gel Permeation Chromatography (GPC) Device (SSC-7200),

Column: Shodex Column (KD-803, KD-805) manufactured by Showa Denko Corporation

Column temperature: 50 ℃

Eluent: N, N'-dimethylformamide (as an additive, lithium bromide-hydrate (LiBr / H ₂ O) is 30 mmol / L, phosphoric acid / anhydrous crystal (o-phosphoric acid) is 30 mmol / L, tetrahydrofuran (THF) is 10ml / L)

Flow rate: 1.0ml / min

Standard samples for calibration curve preparation: 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 approximately 12,000, 4,000, 1,000) of Polymer Laboratories ).

5)內，添加重氫化二甲亞碸(DMSO-d₆，0.05%TMS混合品)1.0ml，施加超音波而使其完全溶解。對於此溶液，以日本電子DATUM股份有限公司製NMR測定器(JNW-ECA500)測定500MHz的質子NMR。醯亞胺化率係將來自在醯亞胺化前後無變化的構造之質子當作基準質子，使用此質子的波峰積分值與出現在9.5~10.0ppm附近的來自醯胺酸之NH基的質子峰積分值，藉由以下之式求得。還有，於下述式中，x係來自醯胺酸的NH基之質子峰積分值，y係基準質子之波峰積分值，α係聚醯胺酸(醯亞胺化率為0%)之情況中的相對於醯胺酸的NH基之質子1個而言，基準質子之個數比例。 The fluorene imidization rate of polyfluorene imine was measured as follows. Put 20mg of polyimide powder into an NMR sample tube (Standard of NMR sampling tube made by Kusano Scientific Co., Ltd.

In 5), 1.0 ml of deuterated dimethylarsine (DMSO-d ₆ , 0.05% TMS mixed product) was added, and ultrasonic waves were applied to completely dissolve. With respect to this solution, a 500 MHz proton NMR was measured with an NMR measuring device (JNW-ECA500) manufactured by Japan Electronics DATUM Corporation. The hydrazone imidization rate uses protons from structures that have not changed before and after hydrazone imidization as the reference protons. The peak integral value of this proton and the proton peak from the NH group of sulfamic acid appearing around 9.5 to 10.0 ppm are used. The integral value is obtained by the following formula. In addition, in the following formula, x is an integral value of a proton peak derived from an NH group of amidine, y is an integral value of a peak of a reference proton, and α is a polyamidate (amidation ratio of 0%). In this case, the ratio of the number of reference protons to one proton of the NH group of the amino acid.

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

<Polymerization of polymer and adjustment of liquid crystal alignment agent> Example 1 TDA, IDI (70) / C4DHyd (Polymer 1) polymerization and adjustment of alignment agent (AL-1)

In a 50 ml 4-neck flask equipped with a mechanical stirrer, measure 1.00 g (3.33 mmol) of TDA and 1.73 g (7.77 mmol) of IDI, dissolve it with 15.9 g of NMP, and add 1.84 g (1.08 mmol) of C4DHyd. Furthermore, 10.0 g of NMP was added, and it stirred at 60 degreeC for 16 hours, and was made to polymerize at the density | concentration of about 15 mass%. As the reaction proceeds, the solution changes from a slurry state to Transparent and becomes a viscous liquid. After the reaction, the viscosity was about 280 mPas and the weight average molecular weight was about 22,300.

In a 50 ml conical flask equipped with a magnetic stirrer, 10.0 g of the obtained polymer 1 solution was weighed, 10.0 g of NMP and 5.0 g of BCS were added, and the mixture was stirred for 1 hour to obtain the alignment agent AL-1 of the present invention.

Example 2 Polymerization of TCA, IDI (70) / mPhDHyd (Polymer 2) and Adjustment of Alignment Agent (AL-2)

In a 50 ml 4-necked flask equipped with a mechanical stirrer, measure 1.00 g (4.46 mmoI) of TCA and 2.31 g (10.41 mmol) of IDI, dissolve it with 24.4 g of NMP, and add 2.76 g (14.21 mmol) of mPhDhyd. Furthermore, 10.0 g of NMP was added, and it stirred at 60 degreeC for 16 hours, and was made to polymerize at the density | concentration of about 15 mass%. As the reaction proceeds, the solution changes from a slurry state to a transparent, viscous liquid. After the reaction, the viscosity was about 390 mPas and the weight average molecular weight was about 31,500.

In a 50-ml Erlenmeyer flask equipped with a magnetic stirrer, 10.0 g of the obtained solution of the polymer 2 was measured, 10.0 g of NMP and 5.0 g of BCS were added, and the mixture was stirred for 1 hour to obtain the alignment agent AL-2 of the present invention. .

Example 3 TDA, IDI (50) / OXDHyd (Polymer 3) polymerization and adjustment of alignment agent (AL-3)

In a 50 ml 4-necked flask equipped with a mechanical stirrer, measure 1.00 g (3.33 mmol) of TDA and 0.74 g (3.33 mmol) of IDI, dissolve it with 10.2 g of NMP, add 0.76 g (6.39 mmol) of OXDHyd, Furthermore, 4.0 g of NMP was added, and it stirred at 60 degreeC for 16 hours, and was made to polymerize at the density | concentration of about 15 mass%. As the reaction proceeds, the solution changes from a slurry state to a transparent, viscous liquid. After the reaction, the viscosity was about 314 mPas and the weight average molecular weight was about 26,300.

In a 50 ml Erlenmeyer flask equipped with a magnetic stirrer, 10.0 g of the obtained solution of the polymer 3 was measured, 10.0 g of NMP and 5.0 g of BCS were added, and the mixture was stirred for 1 hour to obtain the alignment agent AL-3 of the present invention. .

Example 4 TDA, IDI (50) / DA-3MG, OxDHyd (70) (Polymer 4) polymerization and adjustment of alignment agent (AL-4)

In a 50 ml 4-necked flask equipped with a mechanical stirrer, measure 0.74 g (3.33 mmoI) of IDI, dilute with 7.1 g of NMP, add 0.52 g (2.00 mmol) of DA-3MG, and react at room temperature for 3 hours. 1.00 g (3.33 mmol) of TDA was added, 8.6 g of NMP was added to dissolve it, 0.52 g (4.47 mmol) of OxDHyd was added, and the mixture was reacted at 60 ° C for 1 hour and at room temperature for 24 hours. After the reaction, the viscosity was about 512 mPas, and the weight average molecular weight was 34,300.

In a 50 ml Erlenmeyer flask equipped with a magnetic stirrer, measure 10.0 g of the obtained polymer 4 solution, and add 10.0 g of NMP and 5.0 g of BCS were stirred for 1 hour to obtain the alignment agent AL-4 of the present invention.

Example 5 BODA, O-TolDI (50) / C4DHyd, PCH7AB (30) (Polymer 5) polymerization and adjustment of alignment agent (AL-5)

In a 50 ml 4-necked flask equipped with a mechanical stirrer, measure 0.70 g (4.00 mmol) of O-TolDI, add 6.77 g of NMP for dilution, add 0.91 g (2.40 mmol) of PCH7AB, and react at room temperature. 1 After 1 hour, 1.00 g (4.00 mmol) of BODA was added, and g of NMP was further added to dissolve it, 0.94 g (5.38 mmol) of C4DHyd was added, and the mixture was reacted at 60 ° C for 24 hours. As the reaction proceeds, the solution changes from a slurry state to a transparent, viscous liquid. After the reaction, the viscosity was about 210 mPas and the weight average molecular weight was about 19,900.

In a 50-ml Erlenmeyer flask equipped with a magnetic stirrer, 10.0 g of the obtained polymer 5 solution was weighed, 10.0 g of NMP and 5.0 g of BCS were added, and the mixture was stirred for 1 hour to obtain the alignment agent AL-5 of the present invention. .

Example 6 Synthesis of TDA, IDI (70) / C4DHyd (Polymer 1), chemical imidization (Polymer 6) and adjustment of alignment agent (AL-6)

In a 100 ml Erlenmeyer flask equipped with a magnetic stirrer, measure 20.0 g of the polymer obtained in Example 1, and measure 30.0 g of NMP. 1.02 g (9.99 mmol) of acetic anhydride and 0.40 g (5.00 mmol) of pyridine were added and reacted at 50 ° C for 3 hours. After the reaction, the solid was precipitated by pouring into 100 ml of methanol cooled to 10 ° C or lower, and the crude material was recovered by filtration. The dispersion was washed twice with 50 ml of methanol, and dried under vacuum at 60 ° C to obtain a white color. Solid polymer 6.

In a 50 ml Erlenmeyer flask equipped with a magnetic stirrer, measure 1.50 g of the polymer 6 obtained above, add 8.50 g of NMP, stir at room temperature for 24 hours to dissolve, and add 10.0 g of NMP and 5.0 g of NMP. BCS was stirred for 1 hour to obtain the alignment agent AL-6 of the present invention.

Example 7 Synthesis of TDA / C4DHyd (Polymer 7) and Adjustment of Alignment Agent (AL-7)

In a 50 ml 4-necked flask equipped with a mechanical stirrer, 1.00 g (3.33 mmol) of TDA was measured, dissolved in 8.84 g of NMP, 0.56 g (3.20 mmol) of C4DHyd was added, and the reaction was allowed to proceed at room temperature for 24 hours. After the reaction, the viscosity was about 290 mPas and the weight average molecular weight was about 25,100.

In a 50-ml Erlenmeyer flask equipped with a magnetic stirrer, 10.0 g of the obtained polymer 7 solution was weighed, 10.0 g of NMP and 5.0 g of BCS were added, and the mixture was stirred for 1 hour to obtain the alignment agent AL-7 of the present invention. .

Example 8 Synthesis of IsoDI / C4DHyd (Polymer 8) and Adjustment of Alignment Agent (AL-8)

In a 50 ml 4-necked flask equipped with a mechanical stirrer, 1.00 g (4.50 mmol) of IsoDI was measured, dissolved in NMP 9.80 g, 0.73 g (4.18 mmol) of C4DHyd was added, and the mixture was allowed to react at room temperature for 24 hours. After the reaction, the viscosity was about 230 mPas, and the weight average molecular weight was about 24,400.

In a 50-ml Erlenmeyer flask equipped with a magnetic stirrer, 10.0 g of the obtained polymer 5 solution was weighed, 10.0 g of NMP and 5.0 g of BCS were added, and stirred for 1 hour to obtain the alignment agent AL-8 of the present invention .

Comparative Example 1 Synthesis of CBDA / DA-3MG polyamidic acid (PAA-1) and adjustment of alignment agent (AL-9)

In a 50 ml 4-necked flask equipped with a mechanical stirrer, measure 1.00 g (3.87 mmol) of DA-3MG, add 9.75 g of NMP to dissolve it, cool to 10 ° C, add 0.72 g (3.68 mmol) of CBDA, and return After reaching room temperature, the reaction was performed for 6 hours. The viscosity after the reaction was 330 mPas, and the weight average molecular weight was 32,000.

In a 50-ml Erlenmeyer flask equipped with a magnetic stirrer, 10.0 g of the obtained polymer 5 solution was weighed, 10.0 g of NMP and 5.0 g of BCS were added, and the mixture was stirred for 1 hour to obtain the alignment agent AL-9 of the present invention. .

Comparative Example 2

As a comparative liquid crystal alignment agent, SE-7492 manufactured by Nissan Chemical Co., Ltd. was used.

Using the liquid crystal alignment agents obtained in Examples 1 to 8 and Comparative Examples 1 to 2, the evaluation of the liquid crystal alignment film was performed according to the following method.

<Evaluation of coating property of alignment agent>

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

About 1.0 mL of a liquid crystal alignment agent was dropped on the anilox roller, and after performing 10 dry runs, the printing machine was stopped for 10 minutes to dry the printing plate. Then, printing was performed on one Cr substrate, and the printed substrate was left on a hot plate at 70 ° C. for 5 minutes to perform preliminary drying of the coating film and observe the film state. The observation is performed at 50 times with visual observation and with an optical microscope ("ECLIPSE ME600" manufactured by NIKON Corporation), and mainly observes uneven film thickness or uneven film thickness at the edges.

<Evaluation of liquid crystal alignment and voltage retention>

The liquid crystal alignment and voltage retention were evaluated as follows.

[Creation of liquid crystal cell for observing liquid crystal alignment and measuring voltage holding ratio]

After filtering the liquid crystal alignment agent with a 1.0 μm filter, the substrate with electrodes (a glass substrate with a size of 30 mm × 40 mm in length and a thickness of 1.1 mm. The electrodes are rectangular with a width of 10 mm × a length of 40 mm and a thickness of 35 nm ITO electrode), and applied by spin coating. After drying on a hot plate at 50 ° C. for 5 minutes, firing was performed in an IR oven at 180 ° C. for 20 minutes to form a coating film having a film thickness of 100 nm to obtain a substrate with a liquid crystal alignment film. This liquid crystal alignment film was rubbed with a rubbing cloth (YA-20R manufactured by Yoshikawa Chemical Co., Ltd.) (roller diameter: 120 mm, roll rotation number: 1000 rpm, moving speed: 20 mm / sec, press-in length: 0.4 mm) Ultrasonic wave in water was irradiated for 1 minute, washed, water droplets were removed by air flow, and then dried at 80 ° C. for 15 minutes to obtain a substrate with a liquid crystal alignment film.

Prepare two pieces of the above-mentioned substrate with a liquid crystal alignment film, and spread a 4 μm spacer on one of the liquid crystal alignment film surfaces, then print a sealant thereon, and place the other substrate with the rubbing direction opposite and the film surfaces facing each other. After the method is applied, the sealant is hardened to produce air cells. MLC-2041 (manufactured by Merck Co., Ltd.) was injected into the air cell by a reduced pressure injection method, and the injection port was closed 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. overnight to obtain a liquid crystal cell for measuring a voltage holding ratio.

Using the liquid crystal cell for measuring the voltage holding rate obtained by the above program, a voltage of 1 V was applied at a temperature of 60 ° C. for 60 μs, and the voltage after 166.7 ms was measured to calculate how much the voltage can be held as the voltage holding rate. For measuring the voltage holding ratio, a VHR-1 voltage holding ratio measuring device manufactured by Toyo Technology Co., Ltd. was used.

[Evaluation of friction resistance]

After filtering the liquid crystal alignment agent through a 1.0 μm filter, A glass substrate having a size of 30 mm in width × 40 mm in length and a thickness of 1.1 mm. The electrode is a rectangular ITO electrode having a width of 10 mm × a length of 40 mm and a thickness of 35 nm, and was applied by spin coating. After drying on a hot plate at 50 ° C. for 5 minutes, firing was performed in an IR oven at 180 ° C. for 20 minutes to form a coating film having a film thickness of 100 nm to obtain a substrate with a liquid crystal alignment film. This liquid crystal alignment film was rubbed with a rubbing cloth (YA-20R manufactured by Yoshikawa Chemical Co., Ltd.) (roller diameter: 120 mm, number of roller rotations: 1000 rpm, moving speed: 20 mm / sec, press-in length: 0.4 mm), and then a total of With a focus laser microscope, the abrasion resistance was evaluated according to the following criteria.

<Evaluation Criteria>

○: No peeling is good

△: Many shavings or scars are seen

×: When peeled

Table 1 shows the results of the various evaluations described above.

<Evaluation Results of Alignment Agent Printability, Abrasion Resistance, and Cell Display Characteristics>

Comparative Examples 1 and 2 are liquid crystal alignment agents made of polyamidic acid or polyimide. In the material of Comparative Example 1 of polyamic acid, since polyamic acid has very high solubility, good printability is obtained. However, when these materials are used as a liquid crystal alignment film, it is necessary to heat them at a high temperature. It is considered that sufficient properties cannot be obtained in the firing at 180 ° C. in which the amidine imidization reaction proceeds. Comparative Example 2 (SE-7492) is considered the same.

On the other hand, the polymer system of the present invention has high solubility in a solvent and can obtain good printability. In addition, since it has a skeleton having a very strong hydrogen bond, it is possible to obtain high mechanical strength by removing only the solvent, thereby obtaining good alignment film characteristics.

[Industrial availability]

The liquid crystal alignment agent of the present invention can be fired at a low temperature and the printability (solubility of a polymer in a solvent) of the liquid crystal alignment agent is good. By using the liquid crystal alignment agent, a liquid crystal alignment having good liquid crystal alignment and voltage retention can be provided. A liquid crystal display element for a film, and a liquid crystal alignment agent for forming the liquid crystal alignment film.

Therefore, the liquid crystal display element produced by using the liquid crystal alignment agent of the present invention can be a highly reliable liquid crystal display device, and can be applied to TN liquid crystal display elements, STN liquid crystal display elements, TFT liquid crystal display elements, VA liquid crystal display elements, IPS liquid crystal display element, OCB liquid crystal Various types of display elements such as display elements.

Claims (9)

A liquid crystal alignment agent comprising a hydrazine derivative selected from at least one selected from the group consisting of the following formulae (1) to (3) and a formula selected from the following formulae (4) and (5) A polymer obtained by reacting at least one of the compounds;

(In the above formula, W, X, and Z each independently represent a divalent organic group, and Z represents a single bond or a divalent organic group.) For example, the liquid crystal alignment agent of claim 1, which contains a hydrazine derivative of at least one selected from the group consisting of the aforementioned formulae (1) to (3) and a compound of the aforementioned formulae (4) and (5). The resulting polymer. The liquid crystal alignment agent according to claim 1 or 2, wherein the polymer is obtained by further reacting a compound of the following formula (6);

(In the formula, Y is a divalent organic group, and R ₄ each independently represents a hydrogen atom, a methyl group, or an ethyl group). For example, the liquid crystal alignment agent of claim 1, wherein the compound represented by the above formula (4) contains an aliphatic structure and is a hydrazine derivative of at least one selected from the group consisting of the above formulas (1) to (3) A hydrazine derivative of at least one compound selected from the group consisting of:

(In the above formula, R ₁ is an aliphatic hydrocarbon having 1 to 10 carbon atoms). The liquid crystal alignment agent according to any one of claims 1 to 4, wherein the tetracarboxylic dianhydride represented by the above formula (4) is at least one compound selected from the following structures;

The liquid crystal alignment agent according to any one of claims 1 to 5, wherein the compound of the formula (5) is at least one compound selected from the following structures;

(Wherein R ₂ and R ₃ are aliphatic hydrocarbons having 1 to 10 carbon atoms). For example, the liquid crystal alignment agent of any one of items 1 to 6, wherein 0 to A range of 90 mol% is used in combination with the compound of the above formula (4). A liquid crystal alignment film using the liquid crystal alignment agent according to any one of claims 1 to 7. A liquid crystal display element includes the liquid crystal alignment film according to claim 8.