KR101909524B1 - Liquid crystal aligning agent, liquid crystal alignment film and liquid crystal display device - Google Patents

Abstract

(식 (1) 중, R¹은, 탄소수 3∼5의 탄화수소기이고, 당해 탄화수소기에 있어서의 탄소쇄의 도중에 산소 원자를 포함하고 있어도 좋음).[PROBLEMS] To provide a liquid crystal aligning agent having good printability.
(Solution) The liquid crystal aligning agent contains a solvent comprising at least one polymer selected from the group consisting of polyamic acid and polyimide and a pyrrolidone derivative (p) represented by the following formula (1):

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

Description

TECHNICAL FIELD [0001] The present invention relates to a liquid crystal alignment material, a liquid crystal alignment film, and a liquid crystal display device,

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

Conventionally, various types of driving methods have been developed as liquid crystal display devices that differ in electrode structure and physical properties of liquid crystal molecules to be used. For example, TN type, STN type, VA type, in-plane switching type (IPS type) , FFS type, optical compensation band type (OCB type), and the like are known. These liquid crystal display devices have a liquid crystal alignment film for aligning liquid crystal molecules. As a material of the liquid crystal alignment film, polyamic acid and polyimide are generally used in view of good heat resistance, mechanical strength, and various properties such as affinity with liquid crystal.

Recently, liquid crystal display devices are used not only for display terminals such as personal computers, but also for various purposes such as liquid crystal televisions, car navigation systems, mobile phones, smart phones, and information displays. With such a versatility, the liquid crystal display element is required to have a higher quality of display quality and an improved product yield. In addition to the improvement of the driving method and the device structure, one of the constituent members of the liquid crystal display element And a liquid crystal aligning agent which is a material for forming the liquid crystal alignment film are being improved. For example, as a liquid crystal aligning agent, from the viewpoints of display quality and yield, it is required that the coating property (printing property) when applied on a substrate is good, and various materials for improving the printing property are proposed (See, for example, Patent Document 1 or Patent Document 2).

Japanese Laid-Open Patent Publication No. 2011-257527 Japanese Laid-Open Patent Publication No. 2011-257736

There is a growing demand for higher performance and higher yield of the liquid crystal display element and further improvement of the printability of the liquid crystal aligning agent is required.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its main object to provide a liquid crystal aligning agent having good printability, and a liquid crystal alignment film and a liquid crystal display element manufactured using the liquid crystal aligning agent.

DISCLOSURE OF THE INVENTION The present inventors have intensively studied in order to achieve the above problems, and as a result, they found that the above problems can be solved by preparing a liquid crystal aligning agent using a solvent containing a specific compound, and have accomplished the present invention. Specifically, the following liquid crystal aligning agent, liquid crystal alignment film and liquid crystal display element are provided by the present invention.

According to one aspect of the present invention, there is provided a liquid crystal alignment film comprising a polymer comprising at least one polymer selected from the group consisting of polyamic acid and polyimide, and a solvent containing a pyrrolidone derivative (p) represented by the following formula (1) Offer:

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

In the liquid crystal aligning 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 in the solvent is good. In addition, the pyrrolidone derivative (p) has a boiling point of moderately high, and thus it is possible to suppress the volatilization of the solvent from the image of the printing plate upon printing on the substrate of the liquid crystal aligning agent. Therefore, the polymer component is hardly precipitated on the printing machine, and as a result, the printing property (particularly, the printing property in the case of continuous printing over a long period of time, hereinafter also referred to as "long-term printing property") can be improved.

In one embodiment of the liquid crystal aligning agent of the present invention, the content of the pyrrolidone derivative (p) is 10 wt% or more of the total solvent. In this case, the printability can be improved.

Further, as another embodiment, the polymer may be used in combination with 2,3,5-tricarboxycyclopentyl acetic acid dianhydride and 2,4,6,8-tetracarboxybicyclo [3.3.0] octane-2: : 8-2 anhydride, and at least one member selected from the group consisting of a polyamic acid and a polyimide obtained by reacting a diamine with a tetracarboxylic acid dianhydride. When such a polymer and a solvent containing the pyrrolidone derivative (p) are combined, the solubility of the polymer in a solvent is better, and the printing property can be further improved.

Further, in one aspect, the present invention provides a liquid crystal alignment film formed by the above-described liquid crystal aligning agent and a liquid crystal display element comprising the liquid crystal alignment film. Since the liquid crystal alignment film is formed using a liquid crystal aligning agent having good printability, the yield of the liquid crystal display element can be increased.

(Mode for carrying out the invention)

<Liquid Crystal Aligner>

The liquid crystal aligning agent of the present invention contains at least one polymer selected from the group consisting of a polyamic acid obtained by reacting a tetracarboxylic acid dianhydride with a diamine and a polyimide obtained by dehydrocondensing the polyamic acid, The polymer is dissolved in the solvent. Hereinafter, the liquid crystal aligning agent of the present invention will be described in detail.

<Polyamic acid>

[Tetracarboxylic acid dianhydride]

Examples of the tetracarboxylic acid dianhydride used for synthesizing the polyamic acid in the present invention include aliphatic tetracarboxylic acid dianhydride, alicyclic tetracarboxylic dianhydride, and aromatic tetracarboxylic dianhydride . As specific examples of these,

Examples of the aliphatic tetracarboxylic acid dianhydride include 1,2,3,4-butanetetracarboxylic dianhydride and the like;

As the alicyclic tetracarboxylic acid dianhydride, for example, 1,2,3,4-cyclobutanetetracarboxylic acid 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, , 5,9b-hexahydro-8-methyl-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [ (Tetrahydrofuran-2 ', 5'-dione), 5- (2,5-dioxotetrahydro-3 ' 3-cyclohexene-1,2-dicarboxylic anhydride, 3,5,6-tricarboxy-2-carboxymethylnorbornane-2: 3,5: 6-2 anhydride, 2,4,6,8-tetracarboxybicyclo [3.3.0] octane-2: 4,6: 8-2 anhydride, 4,9-dioxatricyclo [5.3.1.0 ^2,6 ] undecane- , 5,8,10-tetraone, cyclohexanetetracarboxylic dianhydride and the like;

As the aromatic tetracarboxylic acid dianhydride, for example, pyromellitic dianhydride and the like; The tetracarboxylic acid dianhydride described in JP-A-2010-97188 can be used.

The tetracarboxylic acid dianhydrides may be used singly or in combination of two or more.

The tetracarboxylic acid dianhydride used for synthesizing the polyamic acid preferably contains an alicyclic tetracarboxylic acid dianhydride in view of good solubility in a solvent. Examples of the alicyclic tetracarboxylic acid dianhydride include 2,3,5-tricarboxycyclopentyl acetic acid dianhydride, 1,3,3a, 4,5,9b-hexahydro-5- (tetrahydro- 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, 2,4,6,8-tetracarboxybicyclo [3.3.0] octane- 2: 4,6: 8-2 anhydride and 1,2,3,4-cyclobutane tetracarboxylic acid dianhydride, and particularly preferably 2,3,5-tricarboxycyclopentyl Acetic acid dianhydride and 2,4,6,8-tetracarboxybicyclo [3.3.0] octane-2: 4,6: 8-2 anhydride.

As the tetracarboxylic acid dianhydride, 2,3,5-tricarboxycyclopentyl acetic acid dianhydride and 2,4,6,8-tetracarboxybicyclo [3.3.0] octane-2: 4,6: 8 -2 anhydride, the total content of these compounds is preferably 10 mol% or more, more preferably 20 mol% to 100 mol%, based on the total amount of the tetracarboxylic acid dianhydride used in the synthesis of the polyamic acid , And still more preferably from 50 to 100 mol%.

[Diamine]

Examples of the diamine used for synthesizing the polyamic acid in the present invention include aliphatic diamines, alicyclic diamines, aromatic diamines, diaminoorganosiloxanes, and the like. These diamines can be used singly or in combination of two or more. Specific examples of the diamine include aliphatic diamines such as 1,1-meta-xylene diamine, 1,3-propanediamine, tetramethylene diamine, pentamethylene diamine, hexamethylene diamine and the like;

As the alicyclic diamine, for example, 1,4-diaminocyclohexane, 4,4'-methylenebis (cyclohexylamine), 1,3-bis (aminomethyl) cyclohexane and the like;

As aromatic diamines, for example, p-phenylenediamine, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfide, 1,5-diaminonaphthalene, 2,2'-dimethyl Diaminobiphenyl, 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl, 2,7-diaminofluorene, 4,4'-diamino Diphenyl ether, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 9,9- 4,4'- (m-tert-butylphenyl) hexafluoropropane, 2,2-bis (4-aminophenyl) hexafluoropropane, Bis (4-aminophenoxy) benzene, 4,4'-bis (4-aminophenoxy) biphenyl, 2,6-diaminopyridine, 3,4 - diaminopyridine, 2,4-diaminopyrimidine, 3,6-diaminoacrylidine, 3,6-diaminocarbazole, N-methyl- , 6-diaminocarbazole, N- (4-aminophenyl) -N, N'-dimethylbenzidine, 1,4-diaminocyclohexane, N, N'- Aminophenyl) -2,3-dihydro-1,3,3-trimethyl-1H-inden-5-amine, 1- (4-amino Phenyl) -2,3-dihydro-1,3,3-trimethyl-1 H-inden-6-amine, 3,5-diaminobenzoic acid, cholestanyloxy-3,5-diaminobenzene, cholesteryl Oxy-3,5-diaminobenzene, cholestanyloxy-2,4-diaminobenzene, cholestenyloxy-2,4-diaminobenzene, 3,5-diaminobenzoic acid cholestanyl, 3,5 (4-aminobenzoyloxy) cholestane, 3,6-bis (4-aminophenoxy) cholestane, 4-aminobenzoic acid cholestane, - (4'-trifluoromethoxybenzoyloxy) cyclohexyl-3,5-diaminobenzoate, 4- (4'-trifluoromethylbenzoyloxy) cyclohexyl-3,5-diaminobenzoate, 1 , 1-bis (4 - ((amino (4 - ((aminophenyl) methyl) phenyl) -4-heptylcyclohexane, 1,1-bis ) Methyl) phenyl) -4-heptylcyclohexane, 1,1-bis (4- (aminophenyl) methyl) , N-diallylamine, 4-aminobenzylamine, 3-aminobenzylamine and the following formula (A-1):

(Wherein X ^I and X ^II each are a single bond, -O-, -COO- or -OCO-, R ^I is an alkanediyl group having 1 to 3 carbon atoms, a is 0 or 1, b is an integer of 0 to 2, c is an integer of 1 to 20, and n is 0 or 1, provided that a and b are not 0 at the same time)

And the like;

Examples of the diaminoorganosiloxane include 1,3-bis (3-aminopropyl) -tetramethyldisiloxane and the like, and diamines described in JP-A-2010-97188 Can be used.

Examples of the divalent group represented by "-X ^I - (R ^I -X ^II ) _n -" in the above formula (A-1) include an alkanediyl group having 1 to 3 carbon atoms, * -O-, Or * -OC ₂ H ₄ -O- (provided that a bonding hand having "*" attached thereto is bonded to a diaminophenyl group). Specific examples of the group "-C _c H _{2c +1} " include a methyl group, an ethyl group, a n-propyl group, an n-butyl group, an n-pentyl group, n-heptadecyl, n-heptadecyl, n-octadecyl, n-hexadecyl, n-hexadecyl, An n-nonadecyl group, and an n-eicosyl group. The two amino groups in the diaminophenyl group are preferably in the 2,4-position or the 3,5-position with respect to the other groups.

Specific examples of the compound represented by the formula (A-1) include compounds represented by the following formulas (A-1-1) to (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 (diamine having an amino group bonded to an aromatic ring) with respect to the total diamine, and contains 50 mol% or more , And particularly preferably 80 mol% or more.

When synthesizing a polyamic acid contained in a liquid crystal aligning agent for a vertical alignment type, a compound having a pretilt component as a diamine may be used in order to give a good vertical alignment property. Specific examples of the diamine having such a pretilt component include dodecanoxy-2,4-diaminobenzene, tetradecanoxy-2,4-diaminobenzene, pentadecanoxy-2,4-diaminobenzene , Hexadecaneoxy-2,4-diaminobenzene, octadecanoxy-2,4-diaminobenzene, dodecaneoxy-2,5-diaminobenzene, tetradecanoxy-2,5-diaminobenzene, Decanoxy-2,5-diaminobenzene, hexadecaneoxy-2,5-diaminobenzene, octadecaneoxy-2,5-diaminobenzene, cholestanyloxy-3,5-diaminobenzene, 3, 5-diaminobenzene, cholestanyloxy-2,4-diaminobenzene, cholestenyloxy-2,4-diaminobenzene, 3,5-diaminobenzoic acid cholestanyl, 5-diaminobenzoic acid cholestenyl, 3,5-diaminobenzoic acid ranostanyl, 3,6-bis (4-aminobenzoyloxy) cholestane, 3,6-bis (4-aminophenoxy) 4- (4 ' -trifluoromethoxybenzoyloxy) cyclohexyl (4 - ((aminophenyl) methyl) -3,5-diaminobenzoate, 4- (4'-trifluoromethylbenzoyloxy) cyclohexyl- Phenyl) -4-butylcyclohexane, 1,1-bis (4 - ((aminophenoxy) methyl) ), 4-heptylcyclohexane, 1,1-bis (4 - ((aminophenyl) methyl) phenyl) -4- (4-heptylcyclohexyl) cyclohexane, . The diamines having a pretilt component can be used singly or in combination of two or more.

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

[Molecular Weight Regulator]

In synthesizing a polyamic acid, a terminal modifier type polymer may be synthesized by using a suitable molecular weight modifier together with the tetracarboxylic dianhydride and the diamine as described above. By using such a polymer having a terminal modification type, the coating property (printing property) of the liquid crystal aligning agent can be further improved.

Examples of the molecular weight regulator include acid monoanhydrides, monoamine compounds, and monoisocyanate compounds. Specific examples thereof include acid anhydrides such as maleic anhydride, phthalic anhydride, itaconic anhydride, n-decylsuccinic anhydride, n-dodecylsuccinic anhydride, n-tetradecylsuccinic anhydride, n-hexadecylsuccinic anhydride My back;

As the monoamine compound, for example, aniline, cyclohexylamine, n-butylamine, n-pentylamine, n-hexylamine, n-heptylamine, n-octylamine and the like;

Examples of the monoisocyanate compound include phenyl isocyanate and naphthyl isocyanate.

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

<Synthesis of polyamic acid>

The ratio of the tetracarboxylic acid dianhydride and the diamine to be used in the synthesis reaction of the polyamic acid in the present invention is such that the ratio of the acid anhydride group of the tetracarboxylic acid dianhydride to the equivalent of one equivalent of the amino group of the diamine is 0.2 to 2 equivalents , More preferably 0.3 to 1.2 equivalents.

The synthesis reaction of the polyamic acid is preferably carried out in an organic solvent. The reaction temperature is preferably -20 ° C to 150 ° C, more preferably 0 ° C to 100 ° C. The reaction time is preferably 0.1 to 24 hours, more preferably 0.5 to 12 hours.

Examples of the organic solvent include aprotic polar solvents, phenol and derivatives thereof, alcohols, ketones, esters, ethers, halogenated hydrocarbons, hydrocarbons, and the like.

Specific examples of these organic solvents include, but are not limited to, the aprotic polar solvents such as N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, Dimethylformamide, dimethylsulfoxide,? -Butyrolactone, tetramethylurea, hexamethylphosphoric triamide, compounds represented by the following formula (1), and the like;

As the phenol derivative, for example, m-cresol, xylenol, halogenated phenol and the like;

Examples of the alcohols include methyl alcohol, ethyl alcohol, isopropyl alcohol, cyclohexanol, ethylene glycol, propylene glycol, 1,4-butanediol, triethylene glycol, ethylene glycol monomethyl ether and the like;

Examples of the ketone include acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, and the like;

As the ester, for example, ethyl lactate, butyl lactate, methyl acetate, ethyl acetate, butyl acetate, methyl methoxypropionate, ethyl ethoxypropionate, diethyl oxalate, diethyl malonate and the like;

Examples of the ether include diethyl ether, ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol-n-propyl ether, ethylene glycol-i-propyl 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 monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, Tetrahydrofuran and the like;

As the halogenated hydrocarbon, for example, dichloromethane, 1,2-dichloroethane, 1,4-dichlorobutane, trichloroethane, chlorobenzene, o-dichlorobenzene and the like;

Examples of the hydrocarbon include hexane, heptane, octane, benzene, toluene, xylene, isoamyl propionate, isoamyl isobutyrate, diisopentyl ether and the like.

Among these organic solvents, at least one selected from the group consisting of an aprotic polar solvent and a group consisting of phenol and its derivatives (the first group of organic solvents), or at least one selected from organic solvents of the first group, , A ketone, an ester, an ether, a halogenated hydrocarbon and a hydrocarbon (a second group of organic solvents). In the latter case, the use ratio of the organic solvent of the second group is preferably 50% by weight or less, more preferably 40% by weight or less based on the total amount of the organic solvent of the first group and the organic solvent of the second group By weight, more preferably not more than 30% by weight.

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

As described above, a reaction solution obtained by dissolving polyamic acid is obtained. The reaction solution may be directly supplied to the preparation of the liquid crystal aligning agent. Alternatively, the polyamic acid contained in the reaction solution may be isolated and then supplied to the preparation of the liquid crystal aligning agent, or after the isolated polyamic acid is purified, . When the polyamic acid is subjected to dehydration ring closure to form a polyimide, the reaction solution may be directly supplied to the dehydration ring-closing reaction. Alternatively, the polyamic acid contained in the reaction solution may be isolated and then subjected to dehydration ring- May be purified and then subjected to a dehydration ring-closing reaction. The polyamic acid can be isolated and purified by a known method.

<Synthesis of polyimide and polyimide>

The polyimide contained in the liquid crystal aligning agent of the present invention can be obtained by imidizing the polyamic acid synthesized as described above by dehydration ring closure.

The polyimide may be a completely imidized product in which all of the arboric acid structure of the polyamic acid which is a precursor thereof is dehydrated and ring-closed, and only a part of the arid acid structure is subjected to dehydration ring closure to form a partial imide cargo . The imide ratio of the polyimide in the present invention is preferably 30% or more, more preferably 50 to 99%, further preferably 60 to 99%. The imidization rate is a percentage of the ratio of the number of imide ring structures to the sum of the number of amide structure and the number of imide ring structure of polyimide. Here, a part of the imide ring may be an isoimide ring.

The dehydration ring closure of the polyamic acid is preferably carried out by a method of heating the polyamic acid, or a method of dissolving the polyamic acid in an organic solvent, adding a dehydrating agent and a dehydrating ring-closing catalyst to the solution, and optionally heating . Of these, the latter method is preferable.

In the method of adding the dehydrating agent and the dehydrating ring-closing catalyst to the solution of the polyamic acid, 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 to 20 mol based on 1 mol of the acid structure of the polyamic acid. As the dehydration ring-closing catalyst, for example, tertiary amines such as pyridine, collidine, lutidine and triethylamine can be used. The amount of the dehydration ring-closing catalyst to be used is preferably 0.01 to 10 mol based on 1 mol of the dehydrating agent to be used. Examples of the organic solvent used in the dehydration ring-closure reaction include the organic solvents exemplified for use in the synthesis of polyamic acid. The reaction temperature of the dehydration cyclization reaction is preferably 0 to 180 캜, more preferably 10 to 150 캜. The reaction time is preferably 1.0 to 120 hours, more preferably 2.0 to 30 hours.

In this way, a reaction solution containing polyimide is obtained. This reaction solution may be provided as it is in the preparation of a liquid crystal aligning agent, or may be supplied to the preparation of a liquid crystal aligning agent after removing the dehydrating agent and the dehydration ring-closing catalyst from the reaction solution. Alternatively, after the polyimide is isolated, Or may be added to the preparation of a liquid crystal aligning agent after purification of the isolated polyimide. These purification operations can be carried out according to a known method.

&Lt; Solution viscosity of polymer >

The polyamic acid and the polyimide obtained as described above preferably have a solution viscosity of 10 to 800 mPa · s and a solution viscosity of 15 to 500 mPa · s, Do. The solution viscosity (mPa 占 퐏) of the polymer is preferably 10 占 퐉 to 10 占 퐉, prepared using a good solvent (good solvent) of the polymer (e.g.,? -Butyrolactone, Measured at 25 캜 using an E-type rotational viscometer with respect to the weight% of the polymer solution.

<Solvent>

In the liquid crystal aligning agent of the present invention, the polymer is dissolved in a solvent. Such a solvent includes a pyrrolidone derivative (p) represented by the following formula (1). The pyrrolidone derivative (p) has good solubility in polyamic acid and polyimide, and boiling point is moderately high. Therefore, by using such a pyrrolidone derivative (p) as at least a part of the solvent, it is possible to suppress the volatilization of the solvent from the printing plate upon printing on the substrate of the liquid crystal aligning agent, And precipitation hardly occurs. As a result, the printing property (particularly, the long-term printing property) can be improved. Further, since the boiling point of the solvent is not excessively high, the amount of the solvent remaining in the coating film after the preliminary heating can be reduced in the case of preheating (prebaking) after printing. Therefore, it is possible to suppress the adhesion of dust to the surface of the coating film after the preliminary heating, thereby suppressing the lowering of the yield of the product.

　　

(In the formula (1), R ¹ is a hydrocarbon group having 3 to 5 carbon atoms and may contain an oxygen atom in the middle of the carbon chain in 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. 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, a group in which at least one methylene group of these groups is substituted with an oxygen atom (hereinafter also referred to as an "oxygen-containing group") in addition to an alkyl group, an alkenyl group and an alkynyl group having 3 to 5 carbon atoms .

Here, examples of the alkyl group having 3 to 5 carbon atoms include n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, My back;

Examples of the alkenyl group having 3 to 5 carbon atoms include 1-propenyl group, 2-propenyl group, 1-methylethynyl group, 2-methyl-1-propenyl group and the like;

Examples of the alkynyl group having 3 to 5 carbon atoms include a 2-propynyl group, a 2-butynyl group and the like.

Examples of the oxygen-containing group include an alkoxyalkyl group having 3 to 5 carbon atoms, and specific examples thereof include a methoxyethyl group, a methoxypropyl group, a methoxybutyl group, an ethoxymethyl group, Ethoxyethyl group and the like.

As R ¹ , an alkyl group or alkoxyalkyl group having 3 to 5 carbon atoms is preferable, and an alkyl group or alkoxyalkyl group having 4 or 5 carbon atoms is more preferable. Specific preferred examples include a tert-butyl group, an n-pentyl group, a methoxypropyl group, and a methoxybutyl group.

Specific examples of the pyrrolidone derivative (p) include N-propyl-2-pyrrolidone, N-butyl-2-pyrrolidone, N- (t- -Pentyl-2-pyrrolidone, N-methoxypropyl-2-pyrrolidone, N-ethoxyethyl-2-pyrrolidone and N-methoxybutyl-2-pyrrolidone. Among them, N-pentyl-2-pyrrolidone, N- (t-butyl) -2-pyrrolidone and N-methoxypropyl-2-pyrrolidone are particularly preferably used. As the pyrrolidone derivative (p), these compounds may be used singly or in combination of two or more kinds.

It is preferable that the content of the pyrrolidone derivative (p) is 5% by weight or more based on the total amount of the solvent contained in the liquid crystal aligning agent from the viewpoint of suitably suppressing precipitation of the polymer during printing and improving the printing property And more preferably 10% by weight or more. The upper limit of the content is preferably 90% by weight or less, more preferably 70% by weight or less, and still more preferably 40% by weight or less based on the total amount of the solvent contained in the liquid crystal aligning agent.

As the solvent used for preparing the liquid crystal aligning agent of the present invention, other solvents than the above-mentioned pyrrolidone derivative (p) can be used. Examples of other solvents include N-methyl-2-pyrrolidone,? -Butyrolactone,? -Butyrolactam, N, N-dimethylformamide, N, N-dimethylacetamide, Methyl-2-pentanone, ethylene glycol monomethyl ether, butyl lactate, butyl acetate, methyl methoxypropionate, ethyl ethoxypropionate, ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol-n Propyl ether, ethylene glycol-n-butyl ether (butyl cellosolve), ethylene glycol dimethyl ether, ethylene glycol ethyl ether acetate, diethylene glycol dimethyl ether, diethylene 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 (DP M), diisobutyl ketone, isoamyl propionate, isoamyl isobutyrate, diisopentyl ether, ethylene carbonate, propylene carbonate and the like. These may be used alone or in combination of two or more.

<Other components>

The liquid crystal aligning agent of the present invention contains such a polymer and a solvent as described above, but may contain other components as required. Such other components include, for example, other polymers other than the above-mentioned polymer, a compound having at least one epoxy group in the molecule (hereinafter referred to as an &quot; epoxy group-containing compound &quot;), and a functional silane compound.

[Other Polymers]

The other polymer may be used for improving solution characteristics and electrical properties. Examples of such other polymers include polyamic acid esters, polyesters, polyamides, polysiloxanes, cellulose derivatives, polyacetals, polystyrene derivatives, poly (styrene phenylmaleimide) derivatives and poly (meth) acrylates .

When the other polymer is added to the liquid crystal aligning agent, the blending ratio thereof is preferably 50% by weight or less, more preferably 0.1 to 40% by weight, further preferably 0.1 to 30% by weight, based on the total amount of the polymer in the composition desirable.

[Epoxy group-containing compound]

The epoxy group-containing compound can be used for improving adhesion to the substrate surface in the liquid crystal alignment film. 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 Diallyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerin diglycidyl ether, trimethylol propane triglycidyl ether, 2,2-dibromonopentyl glycol di N, N, N ', N'-tetraglycidyl-m-xylylenediamine, 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, N, N'-tetraglycidyl-4,4'-diaminodiphenylmethane, N, N-diglycidyl-benzylamine, N, N-diglycidylaminomethylcyclohexane, N-diglycidyl-cyclohexylamine, and the like.

As other examples of the epoxy group-containing compound, an epoxy group-containing polyorganosiloxane described in International Publication No. 2009/096598 may also be used.

When these epoxy compounds are added to the liquid crystal aligning agent, the blending ratio thereof is preferably 40 parts by weight or less, more preferably 0.1 to 30 parts by weight per 100 parts by weight of the total amount of the polymers contained in the liquid crystal aligning agent.

[Functional silane compound]

The functional silane compound can be used for the purpose of improving the printing property of the liquid crystal aligning agent. Examples of such a functional silane compound include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 2-aminopropyltrimethoxysilane, 2-aminopropyltriethoxysilane, N- (2 -Aminoethyl) -3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-ureidopropyltrimethoxysilane, 3-ureidopropyltriethoxy Silane, N-ethoxycarbonyl-3-aminopropyltrimethoxysilane, N-triethoxysilylpropyl triethylenetriamine, 10-trimethoxysilyl-1,4,7-triazadecane, 9-tri Methoxysilyl-3,6-diazanonyl acetate, methyl 9-trimethoxysilyl-3,6-diazanonanoate, N-benzyl-3-aminopropyltrimethoxysilane, Trimethoxysilane, glycidoxymethyltrimethoxysilane, 2-glycidoxyethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane and the like, Can.

When these functional silane compounds are added to the liquid crystal aligning agent, the mixing ratio thereof is preferably 2 parts by weight or less, more preferably 0.02 to 0.2 parts by weight based on 100 parts by weight of the total of the polymers.

As other components, in addition to the above, a compound having at least one oxetanyl group in the molecule, an antioxidant, or the like can be used.

The solid concentration of the liquid crystal aligning agent of the present invention (the ratio of the total weight of the liquid crystal aligning agent to the total weight of the liquid crystal aligning agent other than the solvent) is appropriately selected in consideration of viscosity, volatility, etc., 1 to 10% by weight. That is, the liquid crystal aligning agent of the present invention is applied to the surface of the substrate as described later, and preferably is heated to form a coating film which becomes a liquid crystal alignment film or a liquid crystal alignment film. When the solid concentration is less than 1 wt% , The film thickness of this coating film becomes too small to obtain a good liquid crystal alignment film. On the other hand, when the solid concentration exceeds 10% by weight, the film thickness of the coating film becomes excessively large, so that a good liquid crystal alignment film can not be obtained, and further, the viscosity of the liquid crystal aligning agent increases and the coating property becomes poor.

A particularly preferable range of the solid concentration is different depending on the method used when the liquid crystal aligning agent is applied to the substrate. For example, in the case of the spinner method, the solid content concentration is particularly preferably in the range of 1.5 to 4.5% by weight. In the case of the printing method, it is particularly preferable that the solid concentration is in the range of 3 to 9 wt%, and the solution viscosity is in the range of 12 to 50 mPa · s accordingly. In the case of the ink-jet method, it is particularly preferable that the solid concentration is in the range of 1 to 5 wt%, and accordingly the solution viscosity is in the range of 3 to 15 mPa · s.

The temperature for preparing the liquid crystal aligning agent of the present invention is preferably 10 to 50 占 폚, more preferably 20 to 30 占 폚.

<Liquid Crystal Alignment Film and Liquid Crystal Display Device>

The liquid crystal alignment film of the present invention is formed by the liquid crystal aligning 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 aligning agent. The operation mode of the liquid crystal display element is not particularly limited, and can be applied to various driving methods such as IPS type, TN type, STN type, FFS type, VA type, OCB type, and the like.

Hereinafter, a method of manufacturing a liquid crystal display element of the present invention will be described, and a method of manufacturing a liquid crystal alignment film of the present invention will be described. The liquid crystal display element of the present invention can be produced, for example, by the following steps (1) to (3). In the step (1), the substrate to be used differs depending on a desired operation mode. Steps (2) and (3) are common to each operation mode.

[Process (1): Formation of coating film]

First, the liquid crystal aligning agent of the present invention is coated on a substrate, and then a coated film is formed on the substrate by heating the coated surface.

(1-1) For example, in the case of producing a TN type, STN type or VA type liquid crystal display device, first, two substrates on which a patterned transparent conductive film is formed are paired, and each transparent conductive film- , The liquid crystal aligning agent of the present invention is preferably applied by an offset printing method, a spin coating method, a roll coating method or an inkjet printing method, respectively. Examples of the substrate include glass such as float glass and soda glass; A transparent substrate made of plastic such as polyethylene terephthalate, polybutylene terephthalate, polyether sulfone, polycarbonate, and poly (alicyclic olefin) can be used. As the transparent conductive film to be formed on one surface of the substrate, an ITO film made of NESA film (a registered trademark of PPG Corporation of the US) or indium oxide-tin oxide (In ₂ O ₃ -SnO ₂ ) made of tin oxide (SnO ₂ ) . In order to obtain a patterned transparent conductive film, for example, a method of forming a pattern by photo-etching after forming a pattern-free transparent conductive film, a method of using a mask having a desired pattern in forming a transparent conductive film, have. When applying the liquid crystal aligning agent, a functional silane compound, a functional titanium compound or the like is preferably added to the surface of the substrate on which the coating film is to be formed, in order to improve the adhesion between the substrate surface and the transparent conductive film and the coating film The pre-treatment for pre-coating may be carried out.

Preheating (prebaking) is preferably performed for the purpose of preventing the liquid flow of the applied liquid crystal aligning agent after application of the liquid crystal aligning agent. The prebaking temperature is preferably 30 to 200 캜, more preferably 40 to 150 캜, particularly preferably 40 to 100 캜. The prebaking time is preferably 0.25 to 10 minutes, more preferably 0.5 to 5 minutes. Thereafter, the solvent is completely removed, and a post-baking step is carried out for the purpose of thermally modifying the acid structure present in the polymer as required. The post-baking temperature is preferably 80 to 300 占 폚, and more preferably 120 to 250 占 폚. The post baking time is preferably 5 to 200 minutes, more preferably 10 to 100 minutes. The film thickness of the film thus formed is preferably 0.001 to 1 占 퐉, and more preferably 0.005 to 0.5 占 퐉.

(1-2) In the case of manufacturing an IPS type liquid crystal display element, on the surface of the substrate on which the transparent conductive film patterned in the comb shape is formed, and the opposite substrate on which the conductive film is not formed, And an orientation agent are then applied, and then each coating surface is heated to form a coating film. The substrate and the transparent conductive film to be 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 preferable film thickness of the coating film to be formed are the same as in the above (1-1).

In any of the cases (1-1) and (1-2), a coating film to be an alignment film is formed by applying a liquid crystal aligning agent on a substrate and then removing the organic solvent. At this time, when the polymer contained in the liquid crystal aligning agent of the present invention is a polyamic acid or an imidized polymer having an imidazole ring structure and an arboric acid structure, the dehydration ring-closure reaction is further advanced by further heating after forming the coating film, Or may be a coated film.

[Process (2): rubbing treatment]

In the case of producing a TN type, STN type or IPS type liquid crystal display device, the coating film formed in the step (1) is subjected to a rubbing treatment in which a cloth made of fibers such as nylon, rayon and cotton is rubbed in a certain direction . Accordingly, the alignment ability of the liquid crystal molecules is imparted to the coating film to form a liquid crystal alignment film. On the other hand, in the case of manufacturing a VA type liquid crystal display device, the coating film formed in the above step (1) can be directly used as a liquid crystal alignment film, but the coating film may be rubbed.

The pretilt angle of a part of the liquid crystal alignment film is changed by irradiating a part of the liquid crystal alignment film with ultraviolet light to the liquid crystal alignment film formed as described above or a process in which a resist film is formed on a part of the surface of the liquid crystal alignment film, And then the resist film is removed so that the liquid crystal alignment film has a different liquid crystal aligning ability for each region. In this case, it is possible to improve the visual field characteristic of the obtained liquid crystal display element.

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

Two substrates on which the liquid crystal alignment film is formed as described above are prepared, and the liquid crystal is arranged between the two substrates arranged opposite to each other to manufacture a liquid crystal cell. Here, when the coating film is subjected to the rubbing treatment, the two substrates are opposed to each other such that the rubbing directions of the coating films are at a predetermined angle, for example, orthogonal or anti-parallel to each other.

To produce a liquid crystal cell, for example, the following two methods can be used.

The first method is a conventionally known method. First, two substrates are opposed to each other with a gap (cell gap) interposed therebetween so that the respective liquid crystal alignment films face each other, and the peripheral portions of the two substrates are bonded to each other using a sealant. The liquid crystal is injected and filled in the cell gap, and then the injection hole is sealed to manufacture a liquid crystal cell.

The second method is a so-called ODF (One Drop Fill) method. For example, an ultraviolet curable sealant 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 dropped onto a predetermined number of places on the liquid crystal alignment film surface, And the liquid crystal is spread over the entire surface of the substrate, and then the ultraviolet light is irradiated to the entire surface of the substrate to cure the sealant, thereby manufacturing a liquid crystal cell.

Regardless of the method, the liquid crystal cell manufactured as described above is further heated to a temperature at which the liquid crystal used is isotropic, and then gradually cooled to room temperature to remove the flow orientation at the time of filling the liquid crystal desirable.

The liquid crystal display element of the present invention can be obtained by bonding a polarizing plate to the outer surface of the liquid crystal cell.

As the sealing agent, for example, an epoxy resin containing a curing agent and an aluminum oxide sphere as a spacer can be used.

Examples of the liquid crystal include nematic liquid crystals and smectic liquid crystals. Of these, nematic liquid crystals are preferable, and examples thereof include a cypher base liquid crystal, an agar watch liquid crystal, a biphenyl liquid crystal, a phenyl cyclohexane liquid crystal, , Terphenyl-based liquid crystals, biphenylcyclohexane-based liquid crystals, pyrimidine-based liquid crystals, dioxane-based liquid crystals, bicyclooctane-based liquid crystals, quaternary type liquid crystals and the like. Further, to these liquid crystals, for example, cholesteric liquid crystals such as cholesteryl chloride, cholesteryl nonanoate and cholesteryl carbonate; Chiral agents such as those sold under the trade names "C-15" and "CB-15" (Merck); p-decyloxybenzylidene-p-amino-2-methylbutyl cinnamate, or the like may be added and used.

As the polarizing plate to be bonded to the outer surface of the liquid crystal cell, a polarizing plate in which a polarizing film called "H film" in which iodine is absorbed while polyvinyl alcohol is oriented in a stretched polyvinyl alcohol is sandwiched between cellulose acetate protective films or a polarizing plate comprising H film itself .

The liquid crystal display element of the present invention can be effectively applied to various apparatuses and can be applied to various devices such as a clock, a portable game, a word processor, a notebook personal computer, a car navigation system, a camcorder, a PDA, , Smart phones, various monitors, liquid crystal televisions, and information displays.

[Example]

Hereinafter, the present invention will be described more specifically by way of examples, but the present invention is not limited to these examples.

The solution viscosity of each polymer solution and the imidization rate of polyimide in the synthesis examples were measured by the following methods.

[Solution viscosity of polymer solution]

The solution viscosity [mPa 占 퐏] of the polymer solution was measured with an E-type rotational viscometer at 25 占 폚 for a solution prepared by using a predetermined solvent at a polymer concentration of 10% by weight.

[Imidization Rate of Polyimide]

The polyimide solution was poured into pure water, and the obtained precipitate was sufficiently dried under reduced pressure at room temperature, then dissolved in deuterated dimethyl sulfoxide, and ¹ H-NMR was measured at room temperature using tetramethylsilane as a reference material. From the obtained ¹ H-NMR spectrum, the imidization rate [%] was determined by the equation shown in the following equation (1).

Imidization rate [%] = {(1-A ¹ ) / (A ² x?)} 100 ... (One)

In the formula (1), A ¹ is the peak area derived from the flotone of the NH group near the chemical shift of 10 ppm, A ² is the peak area derived from the other platons, and? The ratio of the number of other flowtones to one of the NH3 groups in the NH3 group).

<Synthesis of polyimide>

Synthesis Example 1: Synthesis of polyimide (PI-1)

(0.1 mole) of 2,3,5-tricarboxycyclopentyl acetic acid dianhydride (TCA) as tetracarboxylic acid dianhydride, 8.6 g (0.08 mole) of p-phenylenediamine (PDA) 10.5 g (0.02 mol) of cholestanyl diaminobenzoate (HCDA) was dissolved in 166 g of N-methyl-2-pyrrolidone (NMP) and the reaction was carried out at 60 DEG C for 6 hours to obtain a polyamic acid solution containing 20 wt% . A small amount of the obtained polyamic acid solution was collected and N-methyl-2-pyrrolidone was added thereto to give a solution having a polyamic acid concentration of 10% by weight, and the solution viscosity was 90 mPa.s.

Next, NMP was added to the obtained polyamic acid solution to prepare a solution having a polyamic acid concentration of 7 wt%, 11.9 g of pyridine and 15.3 g of acetic anhydride were added, and the dehydration ring-closure reaction was carried out at 110 DEG C for 4 hours. After the dehydration ring closure reaction, the solvent in the system was replaced with a new NMP (pyridine and anhydrous acetic acid used in the dehydration ring closure reaction were removed out of the system by this operation; 1) was obtained in an amount of 26% by weight. A small amount of the obtained polyimide solution was collected, and the viscosity of the solution measured by adding NMP to a solution having a polyimide concentration of 10 wt% was 45 mPa..

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

(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 4.0 g (0.02 mol) of 4,4'-diaminodiphenylmethane ) Was dissolved in 157 g of NMP, and the reaction was carried out at 60 DEG C for 6 hours to obtain a solution containing 20 wt% of polyamic acid. A small amount of the obtained polyamic acid solution was collected and NMP was added thereto to obtain a solution having a polyamic acid concentration of 10 wt%, and the solution viscosity was 110 mPa 측정.

Subsequently, NMP was added to the obtained polyamic acid solution to prepare a solution having a polyamic acid concentration of 7 wt%, and 16.6 g of pyridine and 21.4 g of acetic anhydride were added, followed by dehydration ring closure reaction at 110 DEG C for 4 hours. After the dehydration ring closure reaction, the solvent in the system was replaced with a fresh NMP solvent to obtain a solution containing 26% by weight of polyimide (PI-2) having an imidization rate of about 82%. A small amount of the obtained polyimide solution was collected and NMP was added thereto to obtain a solution having a polyimide concentration of 10% by weight, and the solution viscosity was 62 mPa 占 퐏.

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

24.9 g (0.10 mol) of 2,4,6,8-tetracarboxybicyclo [3.3.0] octane-2: 4, 6: 8-2 anhydride (BODA) as tetracarboxylic acid dianhydride, 8.6 g (0.08 mole) of HCDA and 10.4 g (0.02 mole) of HCDA were dissolved in 176 g of NMP and reacted at 60 占 폚 for 6 hours to obtain a solution containing 20 mass% of polyamic acid. A small amount of the obtained polyamic acid solution was collected and NMP was added thereto to obtain a solution having a polyamic acid concentration of 10% by weight, and the solution viscosity was 103 mPa 占 퐏.

Next, NMP was added to the obtained polyamic acid solution to prepare a solution having a polyamic acid concentration of 7 wt%, 11.9 g of pyridine and 15.3 g of acetic anhydride were added, and the dehydration ring-closure reaction was carried out at 110 DEG C for 4 hours. After the dehydration ring closure reaction, the solvent in the system was replaced with a fresh NMP solvent to obtain a solution containing 26% by weight of polyimide (PI-3) having an imidization rate of about 71%. A small amount of the obtained polyimide solution was collected and NMP was added thereto to obtain a solution having a polyimide concentration of 10 wt%, and the solution viscosity was 57 mPa 측정.

&Lt; Preparation of liquid crystal aligning agent &

[Example 1]

NMP, ethylene glycol mono-n-butyl ether (BC) and N-pentyl-2-pyrrolidone (NPP) were added as a solvent to a solution containing 100 parts by weight of the polyimide PI- To prepare a solution having NMP: BC: NPP = 30: 50: 20 (weight ratio) and a solid content concentration of 6.5% by weight. This solution was filtered using a filter having a pore diameter of 1 탆 to prepare a liquid crystal aligning agent (S-1).

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

(S-2) to (S-18) and (SR-1) were obtained in the same manner as in Example 1, except that the polyimide used and the solvent composition were changed as shown in Table 1, ) To (SR-4) were prepared.

&Lt; Evaluation of printability >

The printability of each of the liquid crystal aligning agents prepared above was evaluated. The evaluation was carried out as follows. First, with respect to each of the prepared liquid crystal aligning agents, using a liquid crystal alignment film printing machine (Nippon Shinyu Satsuki Satsuki Co., Ltd .; &quot; S40L-532 &quot; The dropping amount was applied on the surface of the transparent electrode of the glass substrate with transparent electrode made of ITO film under the condition of 20 round trip (about 0.2 g). The application to the substrate was carried out 20 times while using a new substrate at intervals of one minute.

Subsequently, a liquid crystal aligning agent was dispensed (one way) on the anilox roll at intervals of one minute, and an operation of bringing the anilox roll and the printing plate into contact with each other (hereinafter referred to as air operation) was performed 10 times in total , And printing on a glass substrate is not performed). This co-operation is not performed in a normal manufacturing process of the liquid crystal display element but is an operation performed to intentionally perform printing on the substrate of the liquid crystal aligning agent under severe conditions.

After ten times of operation, the printing was performed using a glass substrate. In this printing, five substrates were placed at intervals of 30 seconds after the blank operation, each substrate coated with the liquid crystal aligning agent was heated (prebaked) at 80 DEG C for 1 minute to remove the solvent, and then heated at 200 DEG C for 10 minutes (Post-baking) to form a coating film having a film thickness of about 80 nm. The printability was evaluated by observing the pattern edge portion (outer peripheral portion of the print pattern) of this coating film with a microscope having a magnification of 20 times. In the evaluation, a precipitate was observed in the case of no precipitate (regarded as polyimide) from the first printing after the co-operation to be excellent (O), and a precipitate was observed in the first printing after co-operation, (?) When the precipitate was lost during the printing, and the case where the precipitate was observed even after the main printing was repeated 5 times was evaluated as poor (X). The evaluation results are shown in Table 1 below. In the liquid crystal aligning agent having good printability, it is experimentally confirmed that the precipitate is lost (lost) while the substrate is continuously fed.

The printability of the liquid crystal aligning agent was evaluated by carrying out the same operation as above except that the number of times of the air operation was changed 15 times, 20 times, and 25 times. The evaluation results are shown together in Table 1 below.

&Lt; Evaluation of Drying Level of Membrane Surface &

In the evaluation of the printability, the dried level of the film surface after the pre-baking was evaluated. Evaluation was made as good (O) when no stickiness remained when the film surface reached the hand, and poor (X) when stickiness remained. The evaluation results are shown in Table 1 below. Here, the evaluation was made using the substrate of this printing performed after 10 times of ball operation.

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

With respect to the printability, no precipitate was observed from the first printing after the ten idling cycles in all of the liquid crystal aligning agents of the examples. This was the same after 15 ball operations. In addition, when the number of times of the ball operation was increased by 20 times and 25 times, the precipitates were observed in the first printing of this printing, but the precipitates disappeared until the end of the fifth printing. From these results, it was found that the liquid crystal aligning agent of the Examples hardly generates precipitates during printing and has good printability.

On the contrary, in Comparative Example 1 in which the solvent components were NMP and BC, no precipitate was lost during the main printing after 10 times of the operation and until the end of the main printing of 5 times. Further, it was confirmed that, in addition to NMP and BC as a solvent component, it contained a compound g having 2 carbon atoms of a hydrocarbon group bonded to the nitrogen atom of the pyrrolidone ring (Comparative Example 2) and a compound h having 6 carbon atoms 3) and compound i having 8 carbon atoms (Comparative Example 4), precipitates were not observed in this printing after 10 idling cycles. However, if the number of idle operations is increased by 15 cycles, When precipitates were observed and increased by 25 cycles, the precipitates were not lost until the end of the main printing of 5 times. This is because when the number of carbon atoms of the hydrocarbon group bonded to the nitrogen atom of the pyrrolidone ring is 2 or less, the compound tends to be more volatile than the compounds d, e, and f, and precipitation tends to occur. On the other hand, , the concentration of the pyrrolidone ring in the solvent molecule is lower than in the case of using e, f, so that the solubility of the polyimide is lowered and the precipitation is liable to occur, and as a result, the printing property is not so good .

The drying level of the surface of the coated film after prebaking was good in all of the examples. On the other hand, in Comparative Examples 3 and 4, in Comparative Examples 1 to 4, in which evaluation of printability was comparatively good, the drying level of the coating film surface was poor.

Claims (5)

A liquid crystal aligning agent containing a solvent containing at least one polymer selected from the group consisting of polyamic acid and polyimide and a pyrrolidone derivative (p) represented by the following formula (1)

(In the formula (1), R ¹ is a hydrocarbon group having 4 or 5 carbon atoms and may contain an oxygen atom in the middle of the carbon chain in the hydrocarbon group.) The method according to claim 1,
Wherein the content of the pyrrolidone derivative (p) is 10% by weight or more based on the total amount of the solvent. The method according to claim 1,
Wherein the polymer is at least one of 2,3,5-tricarboxycyclopentyl acetic acid dianhydride and 2,4,6,8-tetracarboxybicyclo [3.3.0] octane-2: 4,6: 8-2 anhydride. Wherein the liquid crystal aligning agent is at least one selected from the group consisting of polyamic acid and polyimide obtained by reacting tetracarboxylic acid dianhydride containing one of N, A liquid crystal alignment film formed using the liquid crystal aligning agent according to any one of claims 1 to 3. A liquid crystal display element comprising the liquid crystal alignment film according to claim 4.