TW201335256A - Liquid crystal alignment agent, liquid crystal alignment film and liquid crystal display - Google Patents

Abstract

A liquid crystal alignment agent with a good printing property is provided. The liquid crystal alignment agent contains at least one polymer selected from a group consisting of polyamic acid and polyimide, and a solvent containing pyrrolidone derivatives (p) represented by the following formula (1). In formula (1), R1 is a hydrocarbon group having 3 to 5 carbons, and an oxygen atom may also be included in carbon chains of the hydrocarbon group.

Description

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

The present invention relates to a liquid crystal alignment agent, a liquid crystal alignment film, and a liquid crystal display element, and more particularly to a liquid crystal alignment agent in which a polymer is dissolved in a solvent, and a liquid crystal alignment film and a liquid crystal display element produced using the liquid crystal alignment agent. .

Conventionally, liquid crystal display elements of various driving methods having different electrode structures or physical properties of liquid crystal molecules to be used have been developed as liquid crystal display elements. For example, a twisted nematic (TN) type or a super twisted nematic is known. (Super Twisted Nematic, STN) type, Vertical Alignment (VA) type, In Plane Switching (IPS) type, Fringe Field Switching (FFS) type, Optically compensated bending type (Optically Compensated) Various liquid crystal display elements such as Bend, OCB). The liquid crystal display elements include a liquid crystal alignment film for aligning liquid crystal molecules. In view of various characteristics such as heat resistance, mechanical strength, and affinity with liquid crystal, polyphthalic acid or polyimine is generally used as a material of the liquid crystal alignment film.

Further, in recent years, liquid crystal display elements have been used not only in display terminals such as personal computers as in the prior art, but also in various applications such as liquid crystal televisions or car navigation systems, mobile phones, smart phones, and information displays. With the versatility of the liquid crystal display device, it is required to further improve the quality of the display quality, improve the yield of the product, improve the driving method or the device structure, and constitute one of the constituent members of the liquid crystal display element. Improvements in a liquid crystal alignment film or a liquid crystal alignment agent as a material for forming the liquid crystal alignment film have been progressing. For example, in the viewpoint of display quality, yield, and the like, the coating property (printability) when applied to a substrate is required to be good, and various materials for improving printability have been proposed (for example, refer to Patent Document 1 or Patent). Literature 2).

[Previous Technical Literature]

[Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2011-257527

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2011-257736

The demand for higher performance or higher yield of the liquid crystal display element is further improved, and the printability of the liquid crystal alignment agent is required to be further improved.

The present invention has been made in view of the above problems, and a main object thereof is to provide a liquid crystal alignment agent having good printability and a liquid crystal alignment film and a liquid crystal display element produced by using the liquid crystal alignment agent.

The inventors of the present invention have conducted intensive studies to achieve the above-mentioned problems, and have found that the above problems can be solved by preparing a liquid crystal alignment agent by using a solvent containing a specific compound, and the present invention has been completed. Specifically, the present invention provides the following liquid crystal alignment agent, liquid crystal alignment film, and liquid crystal display element.

The present invention provides, in one aspect, a liquid crystal alignment agent comprising: at least one polymer selected from the group consisting of polylysine and polyimine, and comprising a formula represented by the following formula (1) a solvent of the pyrrolidone derivative (p);

(In the formula (1), R ¹ is a hydrocarbon group having 3 to 5 carbon atoms, and an oxygen atom may be contained in the middle of the carbon chain in the hydrocarbon group).

In the liquid crystal alignment agent of the present invention, since the pyrrolidone derivative (p) is used as at least a part of the solvent, the solubility of the polymer with respect to the solvent is good. Further, the pyrrolidone derivative (p) has a moderately high boiling point, whereby the solvent can be prevented from volatilizing from the printing machine when the liquid crystal alignment agent is printed on the substrate. Therefore, it is difficult for the polymer component to be deposited on the printing machine, and as a result, the printability (especially, the printability in the case where printing is continued for a long period of time, hereinafter also referred to as "long-term printability") is good.

In one aspect of the liquid crystal alignment agent of the present invention, the content of the pyrrolidone derivative (p) is 10% by weight or more based on the entire solvent. In this case, the printability can be made better.

Further, in another aspect, the polymer is at least one selected from the group consisting of polylysine and polyimine, which comprises 2,3,5-tricarboxyl groups. At least any of tetracarboxylic dianhydride and diamine of cyclopentyl acetic acid dianhydride and 2,4,6,8-tetracarboxybicyclo[3.3.0]octane-2:4,6:8-dianhydride The reaction is obtained. To use such a polymer with the above-mentioned pyrrolidone derivative When the solvent of the organism (p) is combined, the solubility of the polymer in the solvent is further improved, and the printability can be further improved.

Furthermore, the present invention provides a liquid crystal alignment film formed of the liquid crystal alignment agent described above and a liquid crystal display element including the liquid crystal alignment film. Since the liquid crystal alignment film is formed using a liquid crystal alignment agent having good printability, the yield of the liquid crystal display element can be improved.

<Liquid alignment agent>

The liquid crystal alignment agent of the present invention contains at least one selected from the group consisting of polylysine obtained by reacting tetracarboxylic dianhydride with a diamine and polyimine which is obtained by dehydration ring closure of the polyamic acid. A polymer and the polymer is dissolved in a solvent. The liquid crystal alignment agent of the present invention will be described in detail below.

<polylysine>

[tetracarboxylic dianhydride]

Examples of the tetracarboxylic dianhydride for synthesizing the polyamic acid in the present invention include aliphatic tetracarboxylic dianhydride, alicyclic tetracarboxylic dianhydride, and aromatic tetracarboxylic dianhydride. Specific examples of the tetracarboxylic dianhydride include aliphatic 1,4,3,4-butanetetracarboxylic dianhydride, and the like, and examples of the alicyclic tetracarboxylic dianhydride include alicyclic tetracarboxylic dianhydride. 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentyl acetic acid dianhydride, 1,3,3a,4,5,9b-hexahydro-5-( Tetrahydro-2,5-dioxo-3-furanyl)-naphtho[1,2-c]furan-1,3-dione, 1,3,3a,4,5,9b-hexahydro- 8-Methyl-5-(tetrahydro-2,5-dioxo-3-furanyl)-naphtho[1,2-c]furan-1,3-dione, 3-oxabicyclo[3.2 .1] Octane-2,4-dione-6-spiro-3'-(tetrahydrofuran-2',5'-dione), 5-(2,5-dioxotetrahydro-3-furanyl )-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride, 3,5,6-tricarboxy-2-carboxymethylnorbornane-2:3,5:6-dianhydride, 2,4,6,8-tetracarboxybicyclo[3.3.0]octane-2:4,6:8-dianhydride, 4,9-dioxatricyclo[5.3.1.0 ^2,6 ]undecane -3,5,8,10-tetraketone, cyclohexanetetracarboxylic dianhydride, etc., and the aromatic tetracarboxylic dianhydride is, for example, pyromellitic dianhydride, and the like; The tetracarboxylic dianhydride described in Japanese Laid-Open Patent Publication No. 2010-97188.

In addition, the above-mentioned tetracarboxylic dianhydride may be used alone or in combination of two or more.

The tetracarboxylic dianhydride for synthesizing polyamic acid preferably contains an alicyclic tetracarboxylic dianhydride from the viewpoint of good solubility in a solvent. Further, the alicyclic tetracarboxylic dianhydride is preferably selected from the group consisting of 2,3,5-tricarboxycyclopentyl acetic acid dianhydride, 1,3,3a, 4,5,9b-hexahydro-5-(tetrahydro- 2,5-dioxo-3-furanyl)-naphtho[1,2-c]furan-1,3-dione, 1,3,3a,4,5,9b-hexahydro-8-A 5-(4-hydro-2,5-dioxo-3-furanyl)-naphtho[1,2-c]furan-1,3-dione, 2,4,6,8-tetracarboxyl Bicyclo[3.3.0]octane-2:4,6:8-dianhydride and 1,2,3,4-cyclobutane tetracarboxylate At least one of the group consisting of acid dianhydrides is particularly preferably 2,3,5-tricarboxycyclopentyl acetic acid dianhydride and 2,4,6,8-tetracarboxybicyclo[3.3.0]octane-2: At least any of 4,6:8-dianhydride.

Further, the above tetracarboxylic dianhydride comprises 2,3,5-tricarboxycyclopentyl acetic acid dianhydride and 2,4,6,8-tetracarboxybicyclo[3.3.0]octane-2:4,6: In the case of at least any of the dianhydrides, the total content of the compounds is preferably 10 mol% or more, more preferably the total amount of the tetracarboxylic dianhydride used in the synthesis of the polyamic acid. It is 20 mol% to 100 mol%, and further more preferably 50 mol% to 100 mol%.

[diamine]

Examples of the diamine used for the synthesis of the polyamic acid in the present invention include an aliphatic diamine, an alicyclic diamine, an aromatic diamine, and a diamine organic decane. These diamines may be used alone or in combination of two or more. Here, as a specific example of the above diamine, examples of the aliphatic diamine include 1,3-m-xylylenediamine, 1,3-propanediamine, tetramethylenediamine, and pentamethylenediamine. Hexamethylenediamine or the like; examples of the alicyclic diamine include 1,4-diaminocyclohexane, 4,4'-methylenebis(cyclohexylamine), and 1,3-bis(amino group). Methyl)cyclohexane or the like; examples of the aromatic diamine include p-phenylenediamine, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl sulfide, 1,5- Diaminonaphthalene, 2,2'-dimethyl-4,4'-diaminobiphenyl, 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 2 , 7-Diaminoguanidine, 4,4'-diaminodiphenyl ether, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 9,9-bis (4- Aminophenyl)anthracene, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, 2,2-bis(4-aminophenyl)hexafluoropropane, 4, 4'-(p-phenylenediisopropylidene)diphenylamine, 4,4'-(meta-phenyldiisopropylidene)diphenylamine, 1,4-bis(4-aminophenoxy) Benzene, 4,4'-bis(4-aminophenoxy)biphenyl, 2,6-diaminopyridine, 3,4-diaminopyridine, 2,4-diaminopyrimidine, 3,6 -diamine acridine, 3,6-diaminocarbazole, N-methyl-3,6 -diaminocarbazole, N-ethyl-3,6-diaminocarbazole, N-phenyl-3,6-diaminocarbazole, N,N'-bis(4-aminophenyl) )-benzidine, N,N'-bis(4-aminophenyl)-N,N'-dimethylbenzidine, 1,4-bis-(4-aminophenyl)-piperazine, 1 -(4-Aminophenyl)-2,3-dihydro-1,3,3-trimethyl-1H-indole-5-amine, 1-(4-aminophenyl)-2,3- Dihydro-1,3,3-trimethyl-1H-indol-6-amine, 3,5-diaminobenzoic acid, cholesteryloxy-3,5-diaminobenzene, cholestene Alkoxy-3,5-diaminobenzene, cholestyloxy-2,4-diaminobenzene, cholestyloxy-2,4-diaminobenzene, 3,5-di Cholesteryl benzoate, cholesteryl 3,5-diaminobenzoate, lanosteryl 3,5-diaminobenzoic acid, 3,6-bis(4-amine Benzomethyleneoxy)cholestane, 3,6-bis(4-aminophenoxy)cholestane, 4-(4'-trifluoromethoxybenzylideneoxy)cyclohexyl-3, 5-diaminobenzoic acid ester, 4-(4'-trifluoromethylbenzylideneoxy)cyclohexyl-3,5-diaminobenzoic acid ester, 1,1-bis(4-( (aminophenyl)methyl)phenyl)-4-butylcyclohexane, 1,1-bis(4-((aminophenyl)methyl)phenyl)-4-heptylcyclohexane 1,1-bis(4-((aminophenoxy) )methyl)phenyl)-4-heptylcyclohexane, 1,1-bis(4-((aminophenyl)methyl)phenyl)-4-(4-heptylcyclohexyl)cyclohexane Alkane, 2,4-diamino-N,N-diallylaniline, 4-aminobenzylamine, 3-aminobenzylamine, and a compound represented by the following formula (A-1) ,

(wherein, X ^I and X ^II are each a single bond, -O-, -COO- or -OCO-, respectively, R ^I is an alkanediyl group having a carbon number of 1 to 3, a is 0 or 1, and b is 0~ An integer of 2, c is an integer of 1 to 20, and n is 0 or 1. wherein a and b are not 0) at the same time; and the diamine organooxane may, for example, be a 1,3-bis(3-amino group) Further, a diamine described in JP-A-2010-97188 can be used as the propyl)-tetramethyldioxane.

The divalent group represented by "-X ^I -(R ^I -X ^II ) _n -" in the above formula (A-1) is preferably an alkanediyl group having a carbon number of 1 to 3, *-O-, *- COO- or *-OC ₂ H ₄ -O- (wherein a bond with a "*" is bonded to a diaminophenyl group). Specific examples of the radical "-C _c H _2c+1 " include, for example, methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-decyl. , n-decyl, n-dodecyl, n-tridecyl, n-tetradecyl, n-pentadecyl, n-hexadecyl, n-heptadecyl, n-octadecyl, n-nine Alkyl, n-icosyl, and the like. Preferably, the two amine groups in the diaminophenyl group are at the 2,4-position or the 3,5-position relative to the other groups.

Specific examples of the compound represented by the above formula (A-1) include a compound represented by each formula of the following formula (A-1-1) to formula (A-1-3).

The diamine used in the synthesis of the polyamic acid in the present invention preferably contains 30 mol% or more of an aromatic diamine (a diamine whose amine group is bonded to an aromatic ring) with respect to all diamines. It is preferably contained in an amount of 50 mol% or more, particularly preferably 80 mol% or more.

Further, in the case of synthesizing polylysine contained in the liquid crystal alignment agent for vertical alignment type, in order to impart good vertical alignment, it is preferred to use a diamine having a pretilt component as a diamine. Specific examples of such a diamine having a pretilt component include dodecyloxy-2,4-diaminobenzene, tetradecyloxy-2,4-diaminobenzene, and pentadecyloxy group. -2,4-diaminobenzene,hexadecanyloxy-2,4-diaminobenzene, octadecyloxy-2,4-diaminobenzene, dodecyloxy-2,5- Diaminobenzene, tetradecyloxy-2,5-diaminobenzene, pentadecyloxy-2,5-diaminobenzene, hexadecyloxy-2,5-diaminobenzene, Octadecyloxy-2,5-diaminobenzene, cholestyloxy-3,5-diaminobenzene, cholestyloxy-3,5-diaminobenzene, cholestane Benzyl-2,4-diaminobenzene, cholestyloxy-2,4-diaminobenzene, cholesteryl 3,5-diaminobenzoate, 3,5-diamine Cholestyrenyl benzoate, lanosteryl 3,5-diaminobenzoic acid, 3,6-bis(4-aminobenzylideneoxy)cholestane, 3,6-bis ( 4-aminophenoxy)cholestane, 4-(4'-trifluoromethoxybenzylideneoxy)cyclohexyl-3,5-diaminobenzoate, 4-(4'- Trifluoromethyl benzhydryloxy)cyclohexyl-3,5-diaminobenzoate, 1,1-bis(4-((aminophenyl)methyl)phenyl)-4-butyl Cyclohexane, 1,1-bis(4-((aminophenyl)) Phenyl)-4-heptylcyclohexane, 1,1-bis(4-((aminophenoxy)methyl)phenyl)-4-heptylcyclohexane, 1,1-double (4-((Aminophenyl)methyl)phenyl)-4-(4-heptylcyclohexyl)cyclohexane, a diamine represented by the above formula (A-1), and the like. In addition, a diamine having a pretilt component can be used alone. Alternatively, two or more types may be used in combination.

The diamine having a pretilt component preferably contains 5 mol% or more, and more preferably 10 mol% or more, based on the total amount of the diamine.

[Molecular weight regulator]

In the case of synthesizing polyamic acid, a terminally modified polymer may be synthesized by using an appropriate molecular weight modifier together with the tetracarboxylic dianhydride and the diamine as described above. By using this terminal-modified polymer, the coating property (printability) of the liquid crystal alignment agent can be further improved.

Examples of the molecular weight modifier include an acid monoanhydride, a monoamine compound, and a monoisocyanate compound. Specific examples of the compounds include, for example, maleic anhydride, phthalic anhydride, itaconic anhydride, n-decyl succinic anhydride, n-dodecyl succinic anhydride, n-tetradecyl succinic anhydride, and the like. Examples of the monoamine compound include aniline, cyclohexylamine, n-butylamine, n-pentylamine, n-hexylamine, n-heptylamine, n-octylamine, and the like; and the monoisocyanate compound may, for example, beocyanic acid. Phenyl ester, naphthyl isocyanate, and the like.

The use ratio of the molecular weight modifier is preferably 20 parts by weight or less, and more preferably 10 parts by weight or less, based on 100 parts by weight of the total of the tetracarboxylic dianhydride and the diamine to be used.

<Synthesis of polylysine>

The ratio of use of the tetracarboxylic dianhydride to the diamine to be used in the synthesis reaction of the polyaminic acid of the present invention is preferably such that the acid anhydride group of the tetracarboxylic dianhydride becomes 0.2 equivalent based on 1 equivalent of the amine group of the diamine. The ratio of ~2 equivalents is more preferably a ratio of 0.3 equivalents to 1.2 equivalents.

The synthesis reaction of polylysine is preferably carried out in an organic solvent. The reaction temperature at this time is preferably -20 ° C to 150 ° C, and more preferably 0 ° C to 100 ° C. Further, the reaction time is preferably from 0.1 to 24 hours, more preferably from 0.5 to 12 hours.

Here, examples of the organic solvent include an aprotic polar solvent, a phenol and a derivative thereof, an alcohol, a ketone, an ester, an ether, a halogenated hydrocarbon, a hydrocarbon, and the like.

Specific examples of the organic solvent include, for example, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, and N-ethyl-2-pyrrolidone. N,N-dimethylacetamide, N,N-dimethylformamide, dimethyl hydrazine, γ-butyrolactone, tetramethylurea, hexamethylphosphonium triamine, the following formula (1) The compound or the like represented by the above; the phenol derivative may, for example, be m-cresol, xylenol or a halogenated phenol; and the alcohol may, for example, be methanol, ethanol, isopropanol, cyclohexanol or ethylene glycol. Propylene glycol, 1,4-butanediol, triethylene glycol, ethylene glycol monomethyl ether, etc.; Examples of the ketone include acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; and examples of the ester include ethyl lactate, butyl lactate, methyl acetate, ethyl acetate, and butyl acetate. Methyl methoxypropionate, ethyl ethoxypropionate, diethyl oxalate, diethyl malonate, etc.; examples of the ether include diethyl ether, ethylene glycol methyl ether, ethylene glycol ether, and ethylene Alcohol n-propyl ether, ethylene glycol isopropyl ether, ethylene glycol n-butyl ether, ethylene glycol dimethyl ether, ethylene glycol ethyl ether acetate, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol Alcohol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, tetrahydrofuran, etc.; for the above halogenated hydrocarbon, for example, dichloromethane, 1, 2 - dichloroethane, 1,4-dichlorobutane, trichloroethane, chlorobenzene, o-dichlorobenzene, etc.; examples of the above hydrocarbons include hexane, heptane, octane, benzene, toluene, xylene, Isoamyl propionate, isoamyl isobutyrate, diisoamyl ether, and the like.

Among the organic solvents, it is preferred to use one or more selected from the group consisting of an aprotic polar solvent and a phenol and a derivative thereof (the first group of organic solvents), or an organic solvent selected from the first group. One or more kinds of a mixture of one or more selected from the group consisting of alcohols, ketones, esters, ethers, halogenated hydrocarbons, and hydrocarbons (the second group of organic solvents). In the latter case, the ratio of use of the organic solvent as the second group is relative to that of the first group. The total amount of the organic solvent and the organic solvent of the second group is preferably 50% by weight or less, more preferably 40% by weight or less, still more preferably 30% by weight or less.

The amount (a) of the organic solvent to be used is preferably such an amount that the total amount of the tetracarboxylic dianhydride and the diamine (b) is from 0.1% by weight to 50% by weight based on the total amount of the reaction solution (a+b). The amount of %.

A reaction solution obtained by dissolving polylysine was obtained as described above. The reaction solution may be directly supplied to the liquid crystal alignment agent, or may be prepared by isolating the polylysine contained in the reaction solution to the liquid crystal alignment agent, or purifying the isolated polyamic acid to the liquid crystal. Modulation of the alignment agent. When polylysine is subjected to dehydration ring closure to form a polyimine, the reaction solution may be directly supplied to a dehydration ring-closure reaction, or the polylysine contained in the reaction solution may be isolated and dehydrated. The ring closure reaction, or the isolated polylysine is purified and supplied to the dehydration ring closure reaction. The isolation and purification of polylysine can be carried out in accordance with a known method.

<Synthesis of Polyimine and Polyimine>

The polyimine contained in the liquid crystal alignment agent of the present invention can be obtained by subjecting the polylysine synthesized as described above to dehydration ring closure to imidize the ruthenium.

The above polyimine may be a polyglycine which is a precursor thereof Some of the pro-acid structures have a dehydration ring-closed complete quinone imide, and may also be a part of the guanidine structure in which only a part of the proline structure is dehydrated and closed, and the proline structure and the quinone ring structure coexist. The polyamidene in the present invention preferably has a ruthenium iodide ratio of 30% or more, more preferably 50% to 99%, still more preferably 60% to 99%. The ruthenium imidization ratio is a ratio of the number of quinone ring structures to the total number of guanidine structures and the number of quinone ring structures of the polyimine. Here, a part of the quinone ring may also be an isoindole ring.

The dehydration ring closure of polylysine is preferably carried out by a method of heating polylysine; or dissolving polylysine in an organic solvent, adding a dehydrating agent and a dehydration ring-closing catalyst to the solution, as needed The method of heating. Among them, the latter method is selected and used.

In the method of adding a dehydrating agent and a dehydration ring-closure catalyst to the above polyamic acid solution, an acid anhydride such as acetic anhydride, propionic anhydride or trifluoroacetic anhydride can be used as the dehydrating agent. The amount of the dehydrating agent to be used is preferably 0.01 mol to 20 mol with respect to the proline structure of polylysine. As the dehydration ring-closing catalyst, for example, a third amine such as pyridine, trimethylpyridine, dimethylpyridine or triethylamine can be used. The amount of use as the dehydration ring-closure catalyst is preferably 0.01 mol to 10 mol per mol of the dehydrating agent used. As the organic solvent used in the dehydration ring closure reaction, it can be exemplified as polylysine. An organic solvent exemplified as the organic solvent used in the synthesis. The reaction temperature of the dehydration ring closure reaction is preferably from 0 ° C to 180 ° C, more preferably from 10 ° C to 150 ° C. The reaction time is preferably from 1.0 to 120 hours, more preferably from 2.0 to 30 hours.

This was carried out to obtain a reaction solution containing polyimine. The reaction solution may be directly supplied to the liquid crystal alignment agent, or may be supplied to the liquid crystal alignment agent after removing the dehydrating agent and the dehydration ring-closing catalyst from the reaction solution, or may be subjected to segregation of the polyimine to the liquid crystal alignment. The preparation of the agent, or the isolation of the isolated polyimine, can be prepared for the preparation of the liquid crystal alignment agent. These purification operations can be carried out in accordance with a known method.

<Solid viscosity of polymer>

The poly-proline and polyimine obtained as described above, when it is made into a solution having a concentration of 10% by weight, preferably has 10 mPa. s~800 mPa. The solution viscosity of s is more preferably 15 mPa. s~500 mPa. s solution viscosity. Further, the solution viscosity (mPa.s) of the above polymer is a polymerization having a concentration of 10% by weight prepared by using a good solvent (for example, γ-butyrolactone, N-methyl-2-pyrrolidone, etc.) of the polymer. The solution was measured at 25 ° C using an E-type rotational viscometer.

<solvent>

In the liquid crystal alignment agent of the present invention, the above polymer is dissolved in a solvent. This solvent contains the pyrrolidone derivative (p) represented by the following formula (1). The pyrrolidone derivative (p) has good solubility in polyglycine or polyimine, and has a moderately high boiling point. Therefore, by using such a pyrrolidone derivative (p) as at least a part of a solvent, when a liquid crystal alignment agent is printed on a substrate, volatilization of the solvent from the printing machine can be suppressed, and the polymer component becomes difficult to be deposited on the printing machine. . As a result, printability (especially long-term printability) can be improved. Further, since the boiling point of the solvent is not too high, when preheating (pre-baking) is performed after printing, the amount of solvent remaining in the coating film after preheating can be reduced. Therefore, it is possible to suppress the adhesion of dust to the surface of the coating film after the preheating, whereby the decrease in the yield of the product can be suppressed.

(In the formula (1), R ¹ is a hydrocarbon group having 3 to 5 carbon atoms, and may also contain an oxygen atom in the middle of the carbon chain of the hydrocarbon group)

The hydrocarbon group having 3 to 5 carbon atoms in R ¹ in the formula (1) may be saturated or unsaturated, and may be linear or branched. Further, in the hydrocarbon group of R ¹ , an oxygen atom may be contained in the middle of the carbon chain. Specific examples of R ¹ include, for example, an alkyl group, an alkenyl group, or an alkynyl group having 3 to 5 carbon atoms, and a group in which at least one methylene group of the group is substituted with an oxygen atom (hereinafter, Also known as "oxyl-containing" and the like.

Here, examples of the alkyl group having 3 to 5 carbon atoms include n-propyl group, isopropyl group, n-butyl group, second butyl group, isobutyl group, tert-butyl group, n-pentyl group, isopentyl group and the like; Examples of the alkenyl group having 3 to 5 carbon atoms include a 1-propenyl group, a 2-propenyl group, a 1-methylvinyl group, a 2-methyl-1-propenyl group, and the like; and an alkynyl group having a carbon number of 3 to 5, for example. A 2-propynyl group, a 2-butynyl group, etc. are mentioned.

Further, the above-mentioned oxygen-containing group may, for example, be an alkoxyalkyl group having 3 to 5 carbon atoms, and specific examples thereof include methoxyethyl, methoxypropyl, methoxybutyl and B. Oxymethyl group, ethoxyethyl group, and the like.

R ¹ is preferably an alkyl group or alkoxyalkyl group having a carbon number of 3 to 5, and more preferably an alkyl group or alkoxyalkyl group having a carbon number of 4 or 5. Preferable specific examples include a third butyl group, a n-pentyl group, a methoxypropyl group, a methoxybutyl group and the like.

Specific examples of the pyrrolidone derivative (p) include N-propyl-2-pyrrolidone, N-butyl-2-pyrrolidone, N-(t-butyl)-2-pyrrolidone, and N-pentyl group. -2-pyrrolidone, N-methoxypropyl-2-pyridyl Pyrrolidone, N-ethoxyethyl-2-pyrrolidone, N-methoxybutyl-2-pyrrolidone, and the like. Among these compounds, N-pentyl-2-pyrrolidone, N-(t-butyl)-2-pyrrolidone, and N-methoxypropyl-2-pyrrolidone are particularly preferably used. Further, the pyrrolidone derivative (p) may be used alone or in combination of two or more.

The content of the pyrrolidone derivative (p) is preferably 5% by weight based on the total amount of the solvent contained in the liquid crystal alignment agent, from the viewpoint of suppressing the precipitation of the polymer during printing and improving the printability. The above is more preferably 10% by weight or more. In addition, the upper limit of the content of the liquid crystal alignment agent is preferably 90% by weight or less, more preferably 70% by weight or less, and still more preferably 40% by weight or less.

As the solvent to be used in the preparation of the liquid crystal alignment agent of the present invention, a solvent other than the above pyrrolidone derivative (p) can be used. Examples of the other solvent include N-methyl-2-pyrrolidone, γ-butyrolactone, γ-butyrolactam, N,N-dimethylformamide, N,N-dimethylacetamide, and 4 -hydroxy-4-methyl-2-pentanone, ethylene glycol monomethyl ether, butyl lactate, butyl acetate, methyl methoxypropionate, ethyl ethoxypropionate, ethylene glycol methyl ether, Ethylene glycol ether, ethylene glycol n-propyl ether, ethylene glycol isopropyl ether, ethylene glycol n-butyl ether (butyl cellosolve), ethylene glycol dimethyl ether, ethylene glycol ethyl ether acetate, diethylene glycol diethylene glycol Ether, two Ethylene glycol diethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, dipropylene glycol monomethyl ether (DPM) , diisobutyl ketone, isoamyl propionate, isoamyl isobutyrate, diisoamyl ether, ethylene carbonate, propylene carbonate and the like. These organic solvents may be used singly or in combination of two or more.

<Other ingredients>

The liquid crystal alignment agent of the present invention contains the polymer and the solvent as described above, and may contain other components as needed. Examples of the other component include a polymer other than the above polymer, a compound having at least one epoxy group in the molecule (hereinafter referred to as "epoxy group-containing compound"), a functional decane compound, and the like.

[Other polymers]

The other polymers described above can be used to improve solution properties or electrical properties. Examples of the other polymer include polyphthalate, polyester, polyamine, polyoxyalkylene, cellulose derivatives, polyacetal, polystyrene derivatives, and poly(styrene-phenyl malazone). Imine) derivatives, poly(meth)acrylates, and the like.

When other polymers are added to the liquid crystal alignment agent, the compounding ratio is preferably 50% by weight or less, more preferably 0.1% by weight to 40% by weight, even more preferably based on the total amount of the polymer in the composition. It is from 0.1% by weight to 30% by weight.

[Epoxy group-containing compound]

The epoxy group-containing compound can be used to improve the adhesion of the liquid crystal alignment film to the surface of the substrate. Here, examples of the epoxy group-containing compound include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, and new Pentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerol diglycidyl ether, trimethylolpropane triglycidyl ether, 2,2-dibromo neopentyl glycol diglycidyl ether , N,N,N',N'-tetraglycidyl-m-xylylenediamine, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, N,N,N ',N'-tetraglycidyl-4,4'-diaminodiphenylmethane, N,N-diglycidyl-benzylamine, N,N-diglycidyl-aminomethyl ring Hexane, N,N-diglycidyl-cyclohexylamine and the like.

Further, as an example of the epoxy group-containing compound, an epoxy group-containing polyorganosiloxane may be used as disclosed in International Publication No. 2009/096598.

When the epoxy compound is added to the liquid crystal alignment agent, the compounding ratio is preferably 40 parts by weight or less, more preferably 0.1 parts by weight, based on 100 parts by weight of the total of the polymer contained in the liquid crystal alignment agent. ~30 parts by weight.

[functional decane compound]

The functional decane compound can be used for the purpose of improving the printability of the liquid crystal alignment agent. Examples of such a functional decane compound include 3-aminopropyltrimethoxydecane, 3-aminopropyltriethoxydecane, 2-aminopropyltrimethoxydecane, and 2-aminopropyltri Ethoxy decane, N-(2-aminoethyl)-3-aminopropyltrimethoxydecane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxy Decane, 3-ureidopropyltrimethoxydecane, 3-ureidopropyltriethoxydecane, N-ethoxycarbonyl-3-aminopropyltrimethoxydecane, N-triethoxydecane Propyltriethylenetriamine, 10-trimethoxydecyl-1,4,7-triazadecane, 9-trimethoxydecyl-3,6-diazaindolyl acetate, Methyl 9-trimethoxydecyl-3,6-diazepine, N-benzyl-3-aminopropyltrimethoxydecane, N-phenyl-3-aminopropyltrimethoxy Decane, glycidoxymethyltrimethoxydecane, 2-glycidoxyethyltrimethoxydecane, 3-glycidoxypropyltrimethoxydecane, and the like.

When the functional decane compound is added to the liquid crystal alignment agent, the compounding ratio is preferably 2 parts by weight or less, and more preferably 0.02 parts by weight to 0.2 parts by weight based on 100 parts by weight of the total of the polymer.

Further, as the other component, in addition to the above, a compound having at least one propylene oxide group in the molecule, an antioxidant, or the like may be used.

Solid content concentration in the liquid crystal alignment agent of the present invention (the total weight of components other than the solvent in the liquid crystal alignment agent is in the total weight of the liquid crystal alignment agent) The ratio may be appropriately selected in consideration of viscosity, volatility, etc., and is preferably in the range of 1% by weight to 10% by weight. In other words, the liquid crystal alignment agent of the present invention is applied to the surface of the substrate as described later, and is preferably heated to form a coating film as a liquid crystal alignment film or a coating film to be a liquid crystal alignment film. When the concentration of the substance is less than 1% by weight, the film thickness of the coating film is too small to obtain a good liquid crystal alignment film. On the other hand, when the solid content concentration exceeds 10% by weight, the film thickness of the coating film becomes too large to obtain a favorable liquid crystal alignment film, and the viscosity of the liquid crystal alignment agent increases to cause deterioration of coating properties.

A particularly preferable range of the solid content concentration varies depending on the method used when the liquid crystal alignment agent is applied onto the substrate. For example, in the case of using the spin coating method, the solid content concentration is particularly preferably in the range of 1.5% by weight to 4.5% by weight. In the case of using the printing method, it is particularly preferable to set the solid content to a range of 3% by weight to 9% by weight, thereby making the solution viscosity 12 mPa. s~50 mPa. The scope of s. In the case of using the inkjet method, it is particularly preferable to set the solid content to a range of 1% by weight to 5% by weight, thereby making the solution viscosity 3 mPa. s~15 mPa. The scope of s.

The temperature at which the liquid crystal alignment agent of the present invention is prepared is preferably from 10 ° C to 50 ° C, and more preferably from 20 ° C to 30 ° C.

<Liquid alignment film and liquid crystal display element>

The liquid crystal alignment film of the present invention can be formed by a liquid crystal alignment agent prepared as described above. Further, the liquid crystal display element of the present invention comprises a liquid crystal alignment film formed using the liquid crystal alignment agent. The operation mode of the liquid crystal display device is not particularly limited, and can be applied to various driving methods such as an IPS type, a TN type, an STN type, an FFS type, a VA type, and an OCB type.

Hereinafter, a method for producing a liquid crystal display device of the present invention will be described, and in the description, a method for producing a liquid crystal alignment film of the present invention will also be described. The liquid crystal display element of the present invention can be produced, for example, by the following steps (1) to (3). Step (1) uses different substrates depending on the desired mode of operation. Step (2) and step (3) are common to each operation mode.

[Step (1): Formation of coating film]

First, the liquid crystal alignment agent of the present invention is applied onto a substrate, and then the coated surface is heated to form a coating film on the substrate.

(1-1) For example, in the case of manufacturing a TN type, STN type or VA type liquid crystal display element, first, two substrates each provided with a patterned transparent conductive film are used as a pair, preferably by offset printing The liquid crystal alignment agent of the present invention is applied to each of the transparent conductive film forming faces by a spin coating method, a roll coater method or an inkjet printing method. Here, as the substrate, for example, glass such as floating glass or soda glass may be used; and polyethylene terephthalate, polybutylene terephthalate, polyether oxime, polycarbonate, poly(alicyclic olefin) may be used. A transparent substrate such as plastic. As the transparent conductive film provided on one surface of the substrate, a NESA film containing tin oxide (SnO ₂ ) (manufactured by PPG Corporation, registered trademark), and indium oxide-tin oxide (In ₂ O ₃ -SnO ₂ ) may be used. ITO film, etc. In order to obtain a patterned transparent conductive film, for example, a method of forming a pattern by photolithography after forming a transparent conductive film without a pattern, a method of using a mask having a desired pattern when forming a transparent conductive film, or the like can be used. . When the liquid crystal alignment agent is applied, in order to improve the adhesion between the surface of the substrate and the transparent conductive film and the coating film, it is also possible to apply a functional decane compound or a functional titanium to the surface of the substrate surface on which the coating film is to be formed. Pretreatment of compounds and the like.

After the liquid crystal alignment agent is applied, in order to prevent the applied alignment agent from sagging or the like, it is preferred to carry out preheating (prebaking). The pre-baking temperature is preferably from 30 ° C to 200 ° C, more preferably from 40 ° C to 150 ° C, and particularly preferably from 40 ° C to 100 ° C. The prebaking time is preferably from 0.25 minutes to 10 minutes, more preferably from 0.5 minutes to 5 minutes. Thereafter, the solvent is completely removed, and if necessary, a calcination (post-baking) step is carried out for the purpose of thermally imidating the proline structure present in the polymer. The post-baking temperature is preferably from 80 ° C to 300 ° C, more preferably from 120 ° C to 250 ° C. The post-baking time is preferably from 5 minutes to 200 minutes, more preferably from 10 minutes to 100 minutes. The film thickness of the formed film is preferably as described above. 0.001 μm to 1 μm, more preferably 0.005 μm to 0.5 μm.

(1-2) When manufacturing an IPS type liquid crystal display device, the liquid crystal alignment agent of the present invention is applied to a conductive film formation surface of a substrate provided with a transparent conductive film patterned into a comb shape, and One surface of the counter substrate on which the conductive film is not provided is heated next to each coated surface to form a coating film. The material of the substrate and the transparent conductive film used at this time, the coating method, the heating conditions after coating, the patterning method of the transparent conductive film, the pretreatment of the substrate, and the preferred film thickness of the formed coating film, and the above (1) -1) Same.

In any of the above (1-1) and (1-2), the liquid crystal alignment agent is applied onto the substrate, and then the organic solvent is removed to form a coating film which becomes an alignment film. In this case, when the polymer contained in the liquid crystal alignment agent of the present invention is a polyphthalic acid or a ruthenium iodide polymer having a quinone ring structure and a phthalic acid structure, it may be formed after the coating film is formed. Further, heating is carried out to carry out a dehydration ring-closure reaction to prepare a coating film which is further imidized.

[Step (2): Friction treatment]

In the case of manufacturing a TN type, STN type or IPS type liquid crystal display element, the following rubbing treatment is carried out: in a fixed direction by using a roll wound with a cloth (the cloth contains fibers such as nylon, rayon, cotton, etc.) The coating film formed in the above step (1) is rubbed. Thereby applying liquid to the coating film The alignment ability of the crystal molecules, thereby becoming a liquid crystal alignment film. On the other hand, in the case of manufacturing a VA liquid crystal display element, the coating film formed in the above step (1) can be directly used as a liquid crystal alignment film, and the coating film can be subjected to a rubbing treatment.

The liquid crystal alignment film formed as described above may be further subjected to the following treatment so that the liquid crystal alignment film has different liquid crystal alignment ability in each region: the liquid crystal alignment film is made by irradiating a part of the liquid crystal alignment film with ultraviolet rays. The treatment of the pretilt angle change of a part of the area; or after the resist film is formed on a part of the surface of the liquid crystal alignment film, the rubbing treatment is performed in a direction different from the previous rubbing treatment, and then the treatment of the resist film is removed. In this case, the visual field characteristics of the obtained liquid crystal display element can be improved.

[Step (3): Construction of liquid crystal cell]

Two substrates in which the liquid crystal alignment film was formed as described above were prepared, and liquid crystal was placed between the two substrates arranged in the opposite direction to produce a liquid crystal cell. Here, when the coating film is subjected to the rubbing treatment, the two substrates are arranged to face each other at a predetermined angle, for example, orthogonal or anti-parallel, in the rubbing directions of the respective coating films.

When manufacturing a liquid crystal cell, the following two methods are mentioned, for example.

The first method is a method known from the previous one. First, each When the liquid crystal alignment films are opposed to each other, the two substrates are opposed to each other with a gap (cell gap) therebetween, and the peripheral portions of the two substrates are bonded together using a sealant, and the cell gap is defined by the surface of the substrate and the sealant. After filling the liquid crystal into the inside, the injection hole is sealed, thereby manufacturing a liquid crystal cell.

The second method is called the One Drop Fill (ODF) method. For example, an ultraviolet curable sealing material is applied to a predetermined position on one of the two substrates on which the liquid crystal alignment film is formed, and liquid crystal is further added to a predetermined number of portions on the liquid crystal alignment film surface, and then liquid crystal alignment is performed. The other film is bonded to the other surface of the substrate, and the liquid crystal is spread over the entire surface of the substrate. Secondly, the entire surface of the substrate is irradiated with ultraviolet light to cure the sealing agent, thereby producing a liquid crystal cell.

In the case of using any method, it is preferred to further heat the liquid crystal cell manufactured as described above until the liquid crystal used becomes an isotropic phase, and then slowly cool to room temperature, thereby removing the liquid crystal filling. Flow alignment.

Next, the liquid crystal display element of the present invention is obtained by laminating a polarizing plate on the outer surface of the liquid crystal cell.

As the sealant, for example, an epoxy resin containing a curing agent and an alumina ball as a spacer can be used.

The liquid crystal may be a nematic liquid crystal or a smectic liquid crystal, of which a preferred nematic As the liquid crystal, for example, a Schiff base liquid crystal, an oxidized azo liquid crystal, a biphenyl liquid crystal, a phenylcyclohexane liquid crystal, an ester liquid crystal, a terphenyl liquid crystal, a biphenyl cyclohexane liquid crystal, or a pyrimidine can be used. Liquid crystals, dioxane liquid crystals, bicyclooctane liquid crystals, cubic liquid crystals, and the like. Further, for example, a cholesteric liquid crystal such as cholestyr chloride, cholesterol phthalate or cholesterol carbonate may be added to the liquid crystals; and the product names "C-15" and "CB-15" are commercially available. A commercially available chiral agent (manufactured by Merck &Co.); a ferroelectric liquid crystal such as p-methoxybenzylidene-p-amino-2-methylbutylcinnamate.

The polarizing plate to be bonded to the outer surface of the liquid crystal cell may be a polarizing film called "H film" sandwiched between a cellulose acetate protective film (the H film is one surface in which polyvinyl alcohol is stretched to absorb iodine on one side). A polarizing film formed of a polarizing film or a polarizing plate including the H film itself.

The liquid crystal display element of the present invention can be effectively applied to various devices, such as a clock, a portable game machine, a word processor, a notebook computer, a car navigation system, a camcorder, a personal digital assistant (PDA). ), digital cameras, mobile phones, smart phones, various displays, LCD TVs or information displays are used in display devices.

[Example]

Hereinafter, the present invention will be more specifically illustrated by the examples, but the present invention is not limited by the examples.

The solution viscosity of each polymer solution in the synthesis example and the oxime imidization ratio of polyimine can be measured by the following methods.

[Solid viscosity of polymer solution]

Solution viscosity of polymer solution [mPa. s] can be measured by using a T-type rotational viscometer at 25 ° C using a solution having a predetermined concentration of a polymer and a polymer concentration of 10% by weight.

[醯Iminization rate of polyimine]

The polyimine solution is put into pure water, and the obtained precipitate is dried under reduced pressure at room temperature, and then dissolved in dimethyl hydrazine oxime, and measured at room temperature with tetramethyl decane as a reference substance. ¹ H-NMR. From the obtained ¹ H-NMR spectrum, the oxime imidization ratio [%] was determined from the formula represented by the following formula (1).

醯imination rate [%]=(1-A ¹ /A ² ×α)×100...(1)

(In the formula (1), A ¹ is the peak area of the proton derived from the NH group appearing near the chemical shift of 10 ppm, A ² is the peak area derived from other protons, and α is the proton relative to the polymer Proportion of the number of protons of the NH group in the precursor (polyproline)

<Synthesis of Polyimine>

[Synthesis Example 1: Synthesis of Polyimine (PI-1)]

2,3,5-tricarboxycyclopentyl acetic acid dianhydride (TCA) as a tetracarboxylic dianhydride (22.4 g (0.1 mol)), p-phenylenediamine (PDA) as a diamine (8.6 g) (0.08 mol) And 30.5-diaminobenzoic acid cholesteryl ester (HCDA) 10.5 g (0.02 mol) dissolved in N-methyl-2-pyrrolidone (NMP) 166 g, at 60 ° C for 6 hours The reaction gave a solution containing 20% by weight of polyamic acid. A small amount of the obtained polyaminic acid solution was added, and N-methyl-2-pyrrolidone was added to prepare a solution having a polyglycine concentration of 10% by weight, and the measured solution viscosity was 90 mPa. s.

Next, NMP was added to the obtained polyaminic acid solution to prepare a solution having a polyglycine concentration of 7 wt%, and 11.9 g of pyridine and 15.3 g of acetic anhydride were added, and a dehydration ring-closure reaction was carried out at 110 ° C for 4 hours. After the dehydration ring-closure reaction, the solvent in the system is subjected to solvent replacement with a new NMP (by this operation, the pyridine and acetic anhydride used in the dehydration ring-closure reaction are removed to the outside of the system. The following is also the above), thereby obtaining the content. A 26% by weight solution of polyamidolimine (PI-1) having a ruthenium iodide ratio of about 68%. A small amount of the obtained polyimine solution was added, and NMP was added to prepare a solution having a polyimine concentration of 10% by weight, and the measured solution viscosity was 45 mPa. s.

[Synthesis Example 2: Synthesis of Polyimine (PI-2)]

22.5 g (0.1 mol) of TCA as tetracarboxylic dianhydride, 7.6 g (0.07 mol) of PDA as diamine, 5.2 g (0.01 mol) of HCDA, and 4,4'-diaminodiphenyl Methane (DDM) 4.0 g (0.02 mol) was dissolved in NMP 157 g, and reacted at 60 ° C for 6 hours to obtain a solution containing 20% by weight of polyglycolic acid. A small amount of the obtained polyaminic acid solution was added, and NMP was added to prepare a solution having a polyglycine concentration of 10% by weight, and the measured solution viscosity was 110 mPa. s.

Next, NMP was added to the obtained polyaminic acid solution to prepare a solution having a polyglycine concentration of 7 wt%, and 16.4 g of pyridine and 21.4 g of acetic anhydride were added, and a dehydration ring-closure reaction was carried out at 110 ° C for 4 hours. After the dehydration ring closure reaction, the solvent in the system was subjected to solvent replacement with a new NMP, whereby a solution containing 26% by weight of a polyimine (PI-2) having a ruthenium iodide ratio of about 82% was obtained. A small amount of the obtained polyimine solution was added, and NMP was added to prepare a solution having a polyimine concentration of 10% by weight, and the measured solution viscosity was 62 mPa. s.

[Synthesis Example 3: Synthesis of Polyimine (PI-3)]

As a tetracarboxylic dianhydride, 2,4,6,8-tetracarboxybicyclo[3.3.0]octane-2:4,6:8-dianhydride (BODA) 24.9 g (0.10 mol), as two Amine PDA 8.6 g (0.08 mol) and HCDA 10.4 g (0.02 mol) dissolved The reaction was carried out in NMP 176 g at 60 ° C for 6 hours to obtain a solution containing 20% by weight of polylysine. A small amount of the obtained polyaminic acid solution was added, and NMP was added to prepare a solution having a polyglycine concentration of 10% by weight, and the measured solution viscosity was 103 mPa. s.

Next, NMP was added to the obtained polyaminic acid solution to prepare a solution having a polyglycine concentration of 7 wt%, and 11.9 g of pyridine and 15.3 g of acetic anhydride were added, and a dehydration ring-closure reaction was carried out at 110 ° C for 4 hours. After the dehydration ring closure reaction, the solvent in the system was subjected to solvent replacement with a new NMP, thereby obtaining a solution containing 26% by weight of polyimine (PI-3) having a ruthenium iodide ratio of about 71%. A small amount of the obtained polyimine solution was added, and NMP was added to prepare a solution having a polyamidene concentration of 10% by weight, and the measured solution viscosity was 57 mPa. s.

<Modulation of liquid crystal alignment agent>

[Example 1]

Adding NMP, ethylene glycol mono-n-butyl ether (BC) and N-pentyl-2-pyrrolidone (NPP) as a solvent to a solution containing 100 parts by weight of the synthesized polyimine (PI-1) The solvent-forming composition was a solution of NMP:BC:NPP=30:50:20 (weight ratio) and a solid concentration of 6.5% by weight. This solution was filtered using a filter having a pore size of 1 μm to prepare a liquid crystal alignment agent (S-1).

[Example 2 to Example 18, Comparative Example 1 to Comparative Example 4]

The liquid crystal alignment agent (S-2) to liquid crystal alignment agent (S-) was prepared by the same method as in the above Example 1 except that the polyimine and the solvent composition used were changed as described in the following Table 1. 18), liquid crystal alignment agent (SR-1) ~ liquid crystal alignment agent (SR-4).

<Printability evaluation>

The printability was evaluated about each of the liquid crystal alignment agents prepared above. Evaluation was performed in the following manner. First, each liquid crystal alignment agent of the liquid crystal alignment agent to be prepared is a liquid crystal alignment film printer (manufactured by Nippon Photo Printing Co., Ltd., Angstromer, model "S40L-532"), and is applied to an anilox roller. The amount of the liquid crystal alignment agent to be added was applied to the transparent electrode surface of the glass substrate on which the transparent electrode including the ITO film was attached under the condition of 20 drops (about 0.2 g). The coating on the substrate was performed 20 times at a time interval of 1 minute using a new substrate.

Next, the liquid crystal alignment agent was dispensed (single pass) on the anilox roll at intervals of 1 minute, and the anilox roll was brought into contact with the printing plate at this time, and this operation (hereinafter referred to as "empty operation" was collectively performed 10 times (in During this period, printing on the glass substrate is not performed). In addition, this dry operation is not performed in the normal manufacturing flow of the liquid crystal display element, but is performed in an intentional manner in which the liquid crystal alignment agent is printed on the substrate under severe conditions.

After 10 empty runs, the glass substrate was used for official printing. In the main printing, after the idling operation, five substrates were placed at intervals of 30 seconds, and each substrate coated with the liquid crystal alignment agent was heated (prebaked) at 80 ° C for 1 minute to remove the solvent, and then the solvent was removed. Heating (post-baking) was carried out for 10 minutes at 200 ° C to form a coating film having a film thickness of about 80 nm. The print edge was evaluated by observing the pattern edge portion (outer peripheral portion of the printed pattern) of the coating film with a microscope having a magnification of 20 times. The evaluation was carried out in the following manner: the case where the precipitate (which is considered to be a polyimide) was observed in the first official printing after the idling operation was excellent (○), and the first time after the idling operation When the precipitates were observed in the case of the official printing, the precipitates disappeared as good (Δ), and the precipitates were observed as defective (×) even after the fifth printing was repeated. The evaluation results are shown in Table 1 below. In addition, it was found by experiments that the liquid crystal alignment agent having good printability was continuously supplied between the substrates, and the precipitates became better (disappeared).

In addition, the printing operation of the liquid crystal alignment agent was evaluated by performing the same operation as described above except that the number of times of the dry operation was changed to 15 times, 20 times, or 25 times. The results of the evaluation are also shown in Table 1 below.

<Evaluation of the drying grade of the film surface>

Regarding the application of the pre-baked coating film in the above evaluation of printability, evaluation The degree of dryness of the surface of the valence film. The evaluation was performed in such a manner that the feeling of stickiness was not left when the surface of the film was touched by hand as (○), and the feeling of residual stickiness was regarded as defective (×). The evaluation results are shown in Table 1 below. In addition, here, the board|substrate which performed the official printing after 10 times of dry operation was used for evaluation.

In addition, the symbol of the solvent composition and the symbol of the antioxidant in Table 1 have the following meanings, respectively.

a: N-methyl-2-pyrrolidone (NMP)

b: ethylene glycol mono-n-butyl ether (BC)

d: N-pentyl-2-pyrrolidone

e: N-(methoxypropyl)-2-pyrrolidone

f: N-(t-butyl)-2-pyrrolidone

g: N-vinyl-2-pyrrolidone

h: N-cyclohexyl-2-pyrrolidone

i: N-octyl-2-pyrrolidone

Regarding the printability, in the liquid crystal alignment agent of the example, no precipitate was observed in the first official printing after 10 empty runs. The phenomenon is the same after 15 empty runs. In addition, when the number of times of the idling operation was increased to 20 times and 25 times, the precipitate was observed in the first official printing, but the precipitate disappeared until the end of the fifth printing. From these results, it is understood that the liquid crystal alignment agent of the example is less likely to cause precipitates during printing, and the printability is good.

On the other hand, in Comparative Example 1 in which the solvent components were NMP and BC, during the official printing after 10 empty runs, the precipitate did not disappear until the end of the five official printings. Further, in addition to NMP and BC, the solvent component includes a solvent of the compound g having a carbon number of 2 in a hydrocarbon group bonded to a nitrogen atom of a pyrrolidone ring (Comparative Example 2), and a carbon number of 6 In the solvent of the compound h (Comparative Example 3) and the solvent containing the compound i having a carbon number of 8 (Comparative Example 4), no precipitate was observed in the main printing after 10 empty runs, but if it was vacant When the number of times was increased to 15 times, precipitates were observed at the beginning of the official printing, and if it was increased to 25 times, the precipitates did not disappear until the end of the 5th official printing. The reason for this is that if the number of carbon atoms of the hydrocarbon group bonded to the nitrogen atom of the pyrrolidone ring is 2 or less, the compound d, the compound e, and the compound f are more likely to be volatilized, so that precipitation is likely to occur. When the carbon number is 6 or more, the concentration of the pyrrolidone ring in the solvent molecule is lowered as compared with the case of using the compound d, the compound e, and the compound f. Therefore, the solubility of the polyimine is lowered and the precipitation is likely to occur. The result is not so good printability.

Further, the drying grade of the surface of the coating film after prebaking was good in the examples. On the other hand, in Comparative Example 3 and Comparative Example 4 in which the evaluation of printability in Comparative Example 1 to Comparative Example 4 was relatively good, the dryness of the surface of the coating film was poor.

Claims (5)

A liquid crystal alignment agent comprising: at least one polymer selected from the group consisting of polylysine and polyimine, and a pyrrolidone derivative (p) represented by the following formula (1) Solvent In the formula (1), R ¹ is a hydrocarbon group having 3 to 5 carbon atoms, and an oxygen atom may be contained in the middle of the carbon chain in the hydrocarbon group. The liquid crystal alignment agent according to claim 1, wherein the content of the pyrrolidone derivative (p) is 10% by weight or more based on the entire solvent. The liquid crystal alignment agent according to claim 1 or 2, wherein the polymer is at least one selected from the group consisting of polylysine and polyimine. Is composed of a 2,3,5-tricarboxyl ring Reaction of tetracarboxylic dianhydride with diamine of at least any of pentyl acetic acid dianhydride and 2,4,6,8-tetracarboxybicyclo[3.3.0]octane-2:4,6:8-dianhydride And got it. A liquid crystal alignment film formed by using the liquid crystal alignment agent according to any one of claims 1 to 3. A liquid crystal display element comprising the liquid crystal alignment film according to item 4 of the patent application.