JP6492982B2 - Liquid crystal alignment agent, liquid crystal alignment film, and liquid crystal display element - Google Patents

Description

  The present invention relates to a liquid crystal aligning agent, a liquid crystal alignment film, and a liquid crystal display element. More specifically, the present invention relates to a liquid crystal aligning agent that gives a liquid crystal aligning film having good coatability particularly in an ink jet coating method, and a liquid crystal display element excellent in electrical characteristics.

  Currently, as a liquid crystal display element, a liquid crystal alignment film made of polyamic acid, polyimide, or the like is formed on a substrate surface provided with a transparent conductive film such as ITO (indium oxide-tin oxide) to form a substrate for a liquid crystal display element. The two are placed opposite to each other, and a nematic liquid crystal layer having positive dielectric anisotropy is formed in the gap between the substrates to form a sandwich cell, where the major axis of the liquid crystal molecules is from one substrate to the other. A TN type liquid crystal display element having a so-called TN (twisted nematic) type liquid crystal cell that is continuously twisted by 90 ° toward the substrate is known. Further, STN (Super Twisted Nematic) type liquid crystal display elements have been developed which have higher contrast than TN type liquid crystal display elements and have less viewing angle dependency. This STN type liquid crystal display element uses nematic liquid crystal blended with a chiral agent which is an optically active substance as liquid crystal, and the major axis of liquid crystal molecules is continuously twisted over 180 ° between substrates. The birefringence effect generated by the above is utilized.

  In recent years, a lateral electric field type in which two electrodes for driving a liquid crystal are arranged in a comb-like shape on one of a pair of substrates and an electric field parallel to the substrate surface is generated to control liquid crystal molecules. Liquid crystal display elements have been proposed. This element is generally called an in-plane switching type (IPS type) and is known to have a wide viewing angle. In particular, when an IPS type element is used in combination with an optical compensation film, the viewing angle characteristics can be further improved, and a wide viewing angle comparable to that of a cathode ray tube can be obtained without gradation inversion and color change. .

  In addition to these, there are vertical alignment type liquid crystal display elements called an MVA (Multi-Domain Vertical Alignment) method in which liquid crystal molecules having negative dielectric anisotropy are aligned perpendicularly to a substrate and a PVA (Patterned Vertical Alignment) method. It has been proposed (see Patent Document 1 and Non-Patent Document 1). These vertical alignment type liquid crystal display elements are excellent in view of manufacturing process, such as excellent viewing angle and contrast, and need not be rubbed in forming the liquid crystal alignment film.

  In recent years, the spread of liquid crystal televisions has progressed, and a large line called “seventh generation” is in operation. A larger “8th generation” line is also planned. Advantages of using a large line to increase the size of the substrate are that multiple panels can be obtained from a single substrate, reducing process time, reducing costs, and responding to the increase in size of the liquid crystal display element itself. Is mentioned. On the other hand, the disadvantage of increasing the size of the substrate is that it is difficult to ensure the uniformity of printing of the liquid crystal aligning agent over a large area. In particular, when film formation over a large area is performed by an offset printing machine that has been widely employed conventionally, there may be a problem in the electrical properties of the liquid crystal alignment film due to poor printing of the liquid crystal aligning agent. .

  In order to solve the above problems, studies have been made to use an inkjet coating method for forming a liquid crystal alignment film. The merit of the ink jet coating method is that the liquid crystal aligning agent used for printing is substantially equal to the amount of liquid actually applied, and therefore the amount of liquid crystal aligning agent used can be expected to be reduced. In addition, since a printing plate is not used, it is possible to reduce maintenance time, labor, and cost, such as eliminating the need for replacement and cleaning, and flexibility to cope with various panel sizes.

Japanese Patent Laid-Open No. 11-258605

“Liquid Crystal”, Vol. 3 (No. 2), p117 (1999)

  In order to produce a liquid crystal display element with a high yield on a large substrate manufactured by a large line, a liquid crystal aligning agent having better printability than ever has been required in an inkjet coating method. Furthermore, demands for improving display quality in recent years have become more severe. For example, a liquid crystal alignment film having characteristics higher than those up to now has been demanded.

The present invention has been made based on the above circumstances, and one of its purposes is to provide a liquid crystal aligning agent that provides a liquid crystal aligning film that is particularly excellent in printability by an ink jet coating method and excellent in electrical characteristics. is there.
Still other objects and advantages of the present invention will become apparent from the following description.

  The above objects and advantages of the present invention are, firstly, a liquid crystal aligning agent containing at least one polymer (A) selected from the group consisting of polyamic acid, polyimide and polyamic acid ester, and a solvent, It is achieved by a liquid crystal aligning agent characterized in that the solvent contains at least one selected from the group consisting of diethylene glycol propyl methyl ether and diethylene glycol butyl methyl ether.

  Secondly, the above objects and advantages of the present invention are achieved by a liquid crystal display device comprising a liquid crystal alignment film obtained from the above liquid crystal aligning agent.

  Since the liquid crystal aligning agent of this invention is excellent in the applicability | paintability especially when used for the inkjet coating method, it can improve the product yield in the manufacturing process by a large sized line. Moreover, the liquid crystal aligning film obtained from the liquid crystal aligning agent of this invention is excellent in an electrical property, and is suitable for applying to a liquid crystal display element.

  Hereinafter, the present invention will be described in detail.

  The liquid crystal aligning agent of the present invention contains at least one polymer (A) selected from the group consisting of polyamic acid, polyimide and polyamic acid ester as a polymer component, and the polymer (A) is dispersed in a solvent. Alternatively, it is prepared as a liquid composition obtained by dissolution.

≪Polymer (A) ≫
<Polyamic acid>
The polyamic acid in this invention can be obtained by making tetracarboxylic dianhydride and diamine react.

(Tetracarboxylic dianhydride)
Examples of tetracarboxylic dianhydrides used for the synthesis of polyamic acid include aliphatic tetracarboxylic dianhydrides, alicyclic tetracarboxylic dianhydrides, aromatic tetracarboxylic dianhydrides, and the like. Specific examples of these are:
Examples of the aliphatic tetracarboxylic dianhydride include 1,2,3,4-butanetetracarboxylic dianhydride;
Examples of the alicyclic tetracarboxylic dianhydride include 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentylacetic 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- No 1,2-dicarboxylic acid 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-tetraone, cyclohexanetetracarboxylic dianhydride Etc .;
Examples of the aromatic tetracarboxylic dianhydride include pyromellitic dianhydride and the like; respectively, and tetracarboxylic dianhydrides described in JP 2010-97188 A can be used. In addition, the said tetracarboxylic dianhydride can be used individually by 1 type or in combination of 2 or more types.

  The tetracarboxylic dianhydride used for the synthesis preferably contains an alicyclic tetracarboxylic dianhydride from the viewpoint of transparency and solubility in a solvent. Among alicyclic tetracarboxylic dianhydrides, 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, 2,4,6,8-tetracarboxybicyclo [3.3.0] octane-2: 4,6: Preferably, it contains at least one selected from the group consisting of 8-dianhydride and 1,2,3,4-cyclobutanetetracarboxylic dianhydride, and 2,3,5-tricarboxycyclopentylacetic acid dianhydride Thing, 2, , 6,8-tetracarboxybicyclo [3.3.0] octane-2: 4,6: 8-dianhydride and 1,2,3,4-cyclobutanetetracarboxylic dianhydride It is particularly preferred that it contains at least one of the above.

  As the tetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentylacetic acid dianhydride, 2,4,6,8-tetracarboxybicyclo [3.3.0] octane-2: 4,6: 8 -When including at least one selected from the group consisting of dianhydride and 1,2,3,4-cyclobutanetetracarboxylic dianhydride, the total content of these compounds is used for the synthesis of polyamic acid. It is preferably 10 mol% or more, more preferably 20 to 100 mol%, based on the total amount of tetracarboxylic dianhydride.

(Diamine)
Examples of the diamine used for the synthesis of the polyamic acid include aliphatic diamines, alicyclic diamines, aromatic diamines, diaminoorganosiloxanes, and the like. Specific examples of these diamines include, for example, metaxylylenediamine, 1,3-propanediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine and the like as aliphatic diamines;
Examples of alicyclic diamines include 1,4-diaminocyclohexane, 4,4′-methylenebis (cyclohexylamine), 1,3-bis (aminomethyl) cyclohexane and the like;

  Examples of aromatic diamines 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-diaminofluorene, 4,4′-diaminodiphenyl ether, 1,3-bis (4-aminophenoxy) propane, 2, 2-bis [4- (4-aminophenoxy) phenyl] propane, 9,9-bis (4-aminophenyl) fluorene, 2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane, 2 , 2-bis (4-aminophenyl) hexafluoropropane, 4,4 ′-(p-phenylenediisopropylpropylene Den) bisaniline, 4,4 ′-(m-phenylenediisopropylidene) bisaniline, 1,4-bis (4-aminophenoxy) benzene, 4,4′-bis (4-aminophenoxy) biphenyl, 2,6- Diaminopyridine, 3,4-diaminopyridine, 2,4-diaminopyrimidine, 3,6-diaminoacridine, 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 -Trimethyl-1H-indene-5-amine, 1- (4-aminophenyl) -2,3-dihydro-1,3,3-trimethyl-1H-indene-6-amine, 3,5-diaminobenzoic acid, Octadecanoxy-2,5-diaminobenzene, cholestanyloxy-3,5-diaminobenzene, cholestenyloxy-3,5-diaminobenzene, cholestanyloxy-2,4-diaminobenzene, cholestenyloxy-2,4- Diaminobenzene, 3,5-diaminobenzoate cholestanyl, 3,5-diaminobenzoate cholestenyl, 3,5-diaminobenzoate lanostannyl, 3,6-bis (4-aminobenzoyloxy) cholestane, 3,6-bis ( 4-aminophenoxy) cholestane, 4- (4′-trifluoromethoxybenzoyloxy) cyclohexane Xyl-3,5-diaminobenzoate, 4- (4′-trifluoromethylbenzoyloxy) cyclohexyl-3,5-diaminobenzoate, 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, 2,4-diamino-N, N-diallylaniline, 4-aminobenzylamine, 3-amino Benzylamine and the following formula (D-1)

（式（Ｄ−１）中、Ｘ^I及びＸ^IIは、それぞれ独立に、単結合、−Ｏ−、＊−ＣＯＯ−、＊−ＯＣＯ−又は＊−ＮＨ−ＣＯ−（但し、「＊」を付した結合手がジアミノフェニル基と結合する。）であり、Ｒ^Ｉ及びＲ^ＩＩは、それぞれ独立に、炭素数１〜３のアルカンジイル基であり、ａは０又は１であり、ｂは０〜２の整数であり、ｃは１〜２０の整数であり、ｎは０又は１であり、ｍは０又は１である。但し、ａ及びｂが同時に０になることはなく、Ｘ^Ｉが＊−ＮＨ−ＣＯ−の場合、ｎは０である。）
で表される化合物などを；
ジアミノオルガノシロキサンとして、例えば、１，３−ビス（３−アミノプロピル）−テトラメチルジシロキサンなどを、それぞれ挙げることができるほか、特開２０１０−９７１８８号公報に記載のジアミンを用いることができる。なお、これらのジアミンは、１種を単独で又は２種以上組み合わせて使用することができる。

(In Formula (D-1), X ^I and X ^II each independently represent a single bond, —O—, * —COO—, * —OCO— or * —NH—CO— (where “*” is And R ^I and R ^II are each independently an alkanediyl group having 1 to 3 carbon atoms, a is 0 or 1, and b is 0. C is an integer of 1 to 20, n is 0 or 1, and m is 0 or 1. However, a and b are not 0 at the same time, and X ^I is * In the case of -NH-CO-, n is 0.)
A compound represented by:
Examples of the diaminoorganosiloxane include 1,3-bis (3-aminopropyl) -tetramethyldisiloxane, and the like, and diamines described in JP 2010-97188 A can be used. In addition, these diamine can be used individually by 1 type or in combination of 2 or more types.

Examples of the divalent group represented by “—X ^I — (R ^I —X ^II ) _n —” in the formula (D-1) include an alkanediyl group having 1 to 3 carbon atoms, * —O—, * —COO—, * —O—C ₂ H ₄ —O—, or * —NH—CO— (however, a bond marked with “*” is bonded to a diaminophenyl group) are preferred.
Specific examples of the group “—C _c H _{2c + 1} ” include, for example, methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group. Group, n-nonyl group, n-decyl group, n-dodecyl group, n-tridecyl group, n-tetradecyl group, n-pentadecyl group, n-hexadecyl group, n-heptadecyl group, n-octadecyl group, n-nonadecyl group Group, n-eicosyl group and the like. The two amino groups in the diaminophenyl group are preferably in the 2,4-position or 3,5-position with respect to other groups.

  Specific examples of the compound represented by the formula (D-1) include compounds represented by the following formulas (D-1-1) to (D-1-4). .

なお、ジアミンとしては、これら化合物の１種を単独で又は２種以上を組み合わせて使用することができる。

In addition, as diamine, 1 type of these compounds can be used individually or in combination of 2 or more types.

  The diamine used when synthesizing the polyamic acid in the present invention preferably contains an aromatic diamine in an amount of 30 mol% or more, more preferably 50 mol% or more, and more preferably 80 mol% or more. It is particularly preferable.

In the case of using a liquid crystal aligning agent for a TN type, STN type or vertical alignment type liquid crystal display element, a diamine having a pretilt component may be used in order to impart good liquid crystal alignment. As the diamine having such a pretilt component, as the pretilt component, an alkyl group having 4 to 20 carbon atoms, a fluoroalkyl group having 4 to 20 carbon atoms, an alkoxy group having 4 to 20 carbon atoms, or a steroid having 17 to 51 carbon atoms. Examples thereof include a diamine having at least one selected from the group consisting of a group having a skeleton and a group in which a plurality of rings are bonded directly or via a linking group. Specifically, for example, dodecanoxy-2,4-diaminobenzene, tetradecanoxy-2,4-diaminobenzene, pentadecanoxy-2,4-diaminobenzene, hexadecanoxy-2,4-diaminobenzene, octadecanoxy-2,4-diaminobenzene , Dodecanoxy-2,5-diaminobenzene, tetradecanoxy-2,5-diaminobenzene, pentadecanoxy-2,5-diaminobenzene, hexadecanoxy-2,5-diaminobenzene, octadecanoxy-2,5-diaminobenzene, cholestanyloxy- 3,5-diaminobenzene, cholestenyloxy-3,5-diaminobenzene, cholestenyloxy-2,4-diaminobenzene, cholestanyl 3,5-diaminobenzoate, cholestenyl 3,5-diaminobenzoate, 3, Lanostanyl 5-diaminobenzoate, 3,6-bis (4-aminobenzoyloxy) cholestane, 3,6-bis (4-aminophenoxy) cholestane, 4- (4′-trifluoromethoxybenzoyloxy) cyclohexyl-3 , 5-Diaminobenzoate, 4- (4′-trifluoromethylbenzoyloxy) cyclohexyl-3,5-diaminobenzoate, 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) E) cyclohexane, diamines represented by the above formula (D-1), and the like. In addition, the diamine which has a pretilt component can be used individually by 1 type or in combination of 2 or more types.
The total amount of the diamine having a pretilt component is preferably 5 mol% or more, more preferably 10 mol% or more, based on the total diamine.

  When the liquid crystal alignment property is imparted by a photo-alignment method to the coating film prepared using the liquid crystal alignment agent of the present invention, a part or all of the polymer (A) used for the preparation of the liquid crystal alignment agent of the present invention, A polymer having a photoalignment structure is preferred. Here, the photo-alignment structure is a concept including both a photo-alignment group and a decomposition type photo-alignment part. Specifically, structures derived from various compounds that exhibit photoalignment by photoisomerization, photodimerization, photolysis, etc. can be adopted as the photoalignment structure, and for example, azobenzene or a derivative thereof is contained as a basic skeleton. An azobenzene-containing group, a group having a cinnamic acid structure containing cinnamic acid or a derivative thereof as a basic skeleton, a chalcone-containing group containing chalcone or a derivative thereof as a basic skeleton, a benzophenone-containing group containing benzophenone or a derivative thereof as a basic skeleton, Examples thereof include a coumarin-containing group containing coumarin or a derivative thereof as a basic skeleton, and a polyimide-containing structure containing polyimide or a derivative thereof as a basic skeleton.

(Molecular weight regulator)
In synthesizing the polyamic acid, a terminal-modified polymer may be synthesized using an appropriate molecular weight regulator together with the tetracarboxylic dianhydride and diamine as described above. By using such a terminal-modified polymer, the coating property (printability) of the liquid crystal aligning agent can be further improved without impairing the effects of the present invention.

Examples of molecular weight regulators include acid monoanhydrides, monoamine compounds, monoisocyanate compounds, and the like. Specific examples thereof include acid monoanhydrides such as maleic anhydride, phthalic anhydride, itaconic anhydride, n-decylsuccinic anhydride, n-dodecylsuccinic anhydride, n-tetradecylsuccinic. Examples of acid anhydrides and n-hexadecyl succinic acid anhydrides include monoamine compounds such as aniline, cyclohexylamine, and n-butylamine; examples of monoisocyanate compounds include phenyl isocyanate and naphthyl isocyanate. it can.
The use ratio of the molecular weight regulator is preferably 20 parts by weight or less, and more preferably 10 parts by weight or less with respect to 100 parts by weight of the total of the tetracarboxylic dianhydride and diamine used.

<Synthesis of polyamic acid>
The ratio of the tetracarboxylic dianhydride and the diamine used in the polyamic acid synthesis reaction is 0.2 to 2 for the tetracarboxylic dianhydride acid anhydride group to 1 equivalent of the amino group of the diamine. The ratio which becomes an equivalent is preferable, and the ratio which becomes 0.3-1.2 equivalent is more preferable.
The polyamic acid synthesis reaction is preferably carried out in an organic solvent. The reaction temperature at this time is preferably −20 ° C. to 150 ° C., more preferably 0 to 100 ° C. The reaction time is preferably 0.1 to 24 hours, more preferably 0.5 to 12 hours.

Here, examples of the organic solvent include aprotic polar solvents, phenol solvents, alcohols, ketones, esters, ethers, halogenated hydrocarbons, hydrocarbons, and the like.
Specific examples of these organic solvents include aprotic polar solvents such as N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, N-ethyl-2-pyrrolidone, N, N- Dimethylacetamide, N, N-dimethylformamide, dimethylsulfoxide, γ-butyrolactone, tetramethylurea, hexamethylphosphortriamide and the like; phenolic solvents such as phenol, m-cresol, xylenol and halogenated phenol;

Examples of the alcohol 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, etc .; as esters, for example, ethyl lactate, butyl lactate, methyl acetate, ethyl acetate, butyl acetate, methyl methoxypropionate, ethyl ethoxypropionate, diethyl oxalate, diethyl malonate, Isoamyl propionate, isoamyl isobutyrate and the like;
Examples of ethers include diethyl ether, ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol-n-propyl ether, ethylene glycol-n-butyl ether, ethylene glycol dimethyl ether, ethylene glycol ethyl ether acetate, diethylene glycol dimethyl ether, diethylene glycol monomethyl ether, Diethylene glycol monomethyl ether acetate, diethylene glycol propyl methyl ether, diethylene glycol butyl methyl ether, tetrahydrofuran, diisopentyl ether, etc .;
Examples of the halogenated hydrocarbon include dichloromethane, 1,2-dichloroethane, 1,4-dichlorobutane, trichloroethane, chlorobenzene, o-dichlorobenzene, and the like. Examples of the hydrocarbon include hexane, heptane, octane, and benzene. , Toluene, xylene and the like; respectively.

Among these organic solvents, one or more selected from the group consisting of an aprotic polar solvent and a phenolic solvent (hereinafter referred to as organic solvent X), or one or more selected from organic solvent X, alcohol, ketone, It is preferable to use a mixture with one or more selected from the group consisting of esters, ethers, halogenated hydrocarbons and hydrocarbons (hereinafter, organic solvent Y). In the latter case, the use ratio of the organic solvent Y is preferably 50% by weight or less, more preferably 40% by weight or less, and still more preferably 30% by weight with respect to the total amount of the organic solvent X and the organic solvent Y. % Or less.
The amount of organic solvent used (a) is such that the total amount (b) of tetracarboxylic dianhydride and diamine is 0.1 to 50% by weight based on the total amount (a + b) of the reaction solution. It is preferable.

  As described above, a reaction solution obtained by dissolving polyamic acid is obtained. This reaction solution may be used as it is for the preparation of the liquid crystal aligning agent, may be used for the preparation of the liquid crystal aligning agent after isolating the polyamic acid contained in the reaction solution, or the isolated polyamic acid was purified. You may use for preparation of a liquid crystal aligning agent. When polyamic acid is dehydrated and cyclized into a polyimide, the above reaction solution may be directly subjected to dehydration and cyclization reaction, or may be subjected to dehydration and cyclization reaction after isolating the polyamic acid contained in the reaction solution. Alternatively, the isolated polyamic acid may be purified and then subjected to a dehydration ring closure reaction. Isolation and purification of the polyamic acid can be performed according to known methods.

<Polyimide>
The polyimide contained in the liquid crystal aligning agent of the present invention can be obtained by dehydrating and ring-closing imidizing the polyamic acid synthesized as described above.

  The polyimide may be a completely imidized product obtained by dehydrating and cyclizing all of the amic acid structure possessed by the polyamic acid that is the precursor, and only a part of the amic acid structure is dehydrated and cyclized, It may be a partially imidized product in which an imide ring structure coexists. The polyimide in the present invention preferably has an imidation ratio of 30% or more, more preferably 40 to 99%, and still more preferably 50 to 99%. This imidation ratio represents the ratio of the number of imide ring structures to the total of the number of polyimide amic acid structures and the number of imide ring structures in percentage. Here, a part of the imide ring may be an isoimide ring.

The polyamic acid is preferably dehydrated and closed by heating the polyamic acid, or by dissolving the polyamic acid in an organic solvent, adding a dehydrating agent and a dehydrating ring-closing catalyst to the solution, and heating the solution as necessary. . Of these, the latter method is preferred.
In the method of adding a dehydrating agent and a dehydrating ring-closing catalyst to the polyamic acid solution, for example, an acid anhydride such as acetic anhydride, propionic anhydride, or trifluoroacetic anhydride can be used as the dehydrating agent. It is preferable that the usage-amount of a dehydrating agent shall be 0.01-20 mol with respect to 1 mol of the amic acid structure of a polyamic acid. As the dehydration ring closure catalyst, for example, tertiary amines such as pyridine, collidine, lutidine, triethylamine and the like can be used. It is preferable that the usage-amount of a dehydration ring-closing catalyst shall be 0.01-10 mol with respect to 1 mol of dehydrating agents to be used. Examples of the organic solvent used in the dehydration ring-closing reaction include the organic solvents exemplified as those used for the synthesis of polyamic acid. The reaction temperature of the dehydration ring closure reaction is preferably 0 to 180 ° C, more preferably 10 to 150 ° C. 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 used for the preparation of the liquid crystal aligning agent as it is, may be used for the preparation of the liquid crystal aligning agent after removing the dehydrating agent and the dehydrating ring-closing catalyst from the reaction solution, and the liquid crystal after isolating the polyimide. You may use for preparation of an aligning agent, or you may use for preparation of a liquid crystal aligning agent, after purifying the isolated polyimide. These purification operations can be performed according to known methods.

<Polyamic acid ester>
The polyamic acid ester contained in the liquid crystal aligning agent of the present invention is synthesized, for example, by reacting the polyamic acid obtained by the above synthetic reaction with a hydroxyl group-containing compound, a halide, an epoxy group-containing compound, or the like. [II] a method of reacting a tetracarboxylic acid diester with a diamine, and [III] a method of reacting a tetracarboxylic acid diester dihalide with a diamine.

  Here, examples of the hydroxyl group-containing compound used in the method [I] include alcohols such as methanol, ethanol and propanol; phenols such as phenol and cresol. Examples of the halide include methyl bromide, ethyl bromide, stearyl bromide, methyl chloride, stearyl chloride, 1,1,1-trifluoro-2-iodoethane and the like, and as an epoxy group-containing compound, Examples thereof include propylene oxide. The tetracarboxylic acid diester used in the method [II] can be obtained, for example, by ring-opening the tetracarboxylic dianhydride exemplified in the synthesis of the polyamic acid using the above alcohols. The tetracarboxylic acid diester dihalide used in the method [III] can be obtained by reacting the tetracarboxylic acid diester obtained as described above with an appropriate chlorinating agent such as thionyl chloride. As the diamine used in the methods [II] and [III], the diamines exemplified in the synthesis of the polyamic acid can be used. The polyamic acid ester may have only an amic acid ester structure, or may be a partially esterified product in which an amic acid structure and an amic acid ester structure coexist.

  The reaction solution containing the polyamic acid ester may be used for the preparation of the liquid crystal aligning agent as it is, or may be used for the preparation of the liquid crystal aligning agent after removing the dehydrating agent and the dehydrating ring-closing catalyst from the reaction solution. May be used for preparing a liquid crystal aligning agent, or may be used for preparing a liquid crystal aligning agent after purifying the isolated polyamic acid ester. These purification operations can be performed according to known methods.

<Solution viscosity, reduced viscosity and weight average molecular weight>
The polyamic acid, polyimide and polyamic acid ester obtained as described above preferably have a solution viscosity of 10 to 800 mPa · s, when this is made into a solution having a concentration of 10% by weight. More preferably, it has a solution viscosity of s. In addition, the solution viscosity (mPa · s) of the above polymer is based on a polymer solution having a concentration of 10% by weight prepared using a good solvent for the polymer (eg, γ-butyrolactone, N-methyl-2-pyrrolidone, etc.). The value measured at 25 ° C. using an E-type rotational viscometer.
The reduced viscosity is not particularly limited as long as a uniform coating film can be formed, but is preferably 0.05 to 3.0 dl / g, and preferably 0.1 to 2.5 dl / g. Is more preferable, and it is still more preferable that it is 0.3-1.5 dl / g.
For the polyamic acid, polyimide and polyamic acid ester contained in the liquid crystal aligning agent of the present invention, the weight average molecular weight in terms of polystyrene measured by gel permeation chromatography (GPC) is preferably 500 to 100,000. More preferably, it is 000-50,000.

≪Solvent≫
The liquid crystal aligning agent of this invention contains at least 1 type (henceforth a specific solvent (B)) selected from the group which consists of diethylene glycol propyl methyl ether and diethylene glycol butyl methyl ether as a solvent component. By including such a specific solvent (B) in a liquid crystal aligning agent, it becomes what was excellent in the printability in the inkjet coating method especially.

  With respect to the specific solvent (B), the diethylene glycol propyl methyl ether may be either a linear or branched propyl group, and specific examples include diethylene glycol n-propyl methyl ether and diethylene glycol isopropyl methyl ether. It is done. Preferably, it is diethylene glycol isopropyl methyl ether. Further, as diethylene glycol butyl methyl ether, the butyl group portion may be either linear or branched, specifically, diethylene glycol n-butyl methyl ether, diethylene glycol isobutyl methyl ether, diethylene glycol sec-butyl methyl ether. Etc. Diethylene glycol n-butyl methyl ether is preferable. In addition, a specific solvent (B) can be used individually by 1 type or in combination of 2 or more types.

(Other solvents)
It is preferable that the liquid crystal aligning agent of this invention contains other solvents other than the said specific solvent (B) as a solvent component. Examples of the other solvent include a solvent capable of dissolving the polymer (A) contained in the liquid crystal aligning agent of the present invention (hereinafter also referred to as “first solvent”), and a poor solvent for the polymer (A). Thus, organic solvents other than the specific solvent (B) can be mentioned.
The first solvent may be a good solvent for the polymer (A), and preferred specific examples thereof include N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, and N-pentyl-2. -Pyrrolidone, 3-methoxy-N, N-dimethylpropionamide, N, N, 2-trimethylpropionamide, 3-butoxy-N, N-dimethylpropionamide, γ-butyrolactone, γ-butyrolactam, N, N-dimethyl Examples include formamide, N, N-dimethylacetamide, 1,3-dimethyl-2-imidazolidinone, N-ethyl-2-pyrrolidone, dimethyl sulfoxide, tetramethylurea, hexamethylphosphortriamide, m-cresol and the like. In addition, the 1st solvent can use said thing individually by 1 type or in mixture of 2 or more types.

  Examples of organic solvents other than the specific solvent (B) that are poor solvents for the polymer (A) include, for example, methyl 2-hydroxyisobutyrate, ethylene glycol monomethyl ether, butyl lactate, butyl acetate, and methylmethoxypropione. -Ethyl ethoxypropionate, ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol-n-propyl ether, ethylene glycol-i-propyl ether, ethylene glycol-n-butyl ether (butyl cellosolve), ethylene glycol dimethyl ether, Ethylene glycol ethyl ether acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether acetate, diethyl Glycol monoethyl ether acetate, dipropylene glycol monomethyl ether (DPM), diisobutyl ketone, isoamyl propionate, isoamyl isobutyrate, ethylene carbonate, propylene carbonate, diacetone alcohol, diethylene glycol diethyl ether, diisopentyl ether, propylene glycol A diacetate etc. can be mentioned. The said organic solvent can use the said thing individually by 1 type or in mixture of 2 or more types. Hereinafter, a group consisting of an organic solvent other than the specific solvent (B) and the specific solvent (B), which is a poor solvent for the polymer (A), is also referred to as a “second solvent”.

  The content ratio of the specific solvent (B) (the total amount when two or more are used) is a liquid crystal alignment from the viewpoint of suppressing the precipitation of the polymer (A) while improving the printability by the ink jet coating method. It is preferable to set it as 90 weight% or less with respect to the whole quantity of the solvent contained in an agent. More preferably, it is 85 weight% or less, More preferably, it is 80 weight% or less, Especially preferably, it is 75 weight% or less. The lower limit of the content ratio is not particularly limited, but is preferably 1% by weight or more.

From the viewpoint of suppressing the precipitation of the polymer (A), the content ratio of the first solvent is preferably 5% by weight or more, more preferably 10% by weight with respect to the total amount of the solvent contained in the liquid crystal aligning agent. % Or more, more preferably 20% by weight or more. Further, the upper limit value of the content ratio of the first solvent is preferably 95% with respect to the total amount of the solvent contained in the liquid crystal aligning agent from the viewpoint of suitably obtaining the effect of the addition of the specific solvent (B). % Or less, more preferably 90% by weight or less, and still more preferably 85% by weight or less.
Of the second solvent, the content of the organic solvent other than the specific solvent (B) is preferably 80% by weight or less, more preferably 70% by weight with respect to the total amount of the solvent contained in the liquid crystal aligning agent. % Or less, more preferably 50% by weight or less, and particularly preferably 30% by weight or less.
The ratio of the first solvent to the second solvent is such that the amount of the second solvent used relative to the amount of the first solvent used is 0.03 times (weight) or more from the viewpoint of improving the coating property to the substrate. Is preferable, and more preferably 0.05 times (weight) or more. Further, from the viewpoint of suppressing the precipitation of the polymer, it is preferably 2.5 times (weight) or less, and more preferably 2.0 times (weight) or less.

《Other ingredients》
The liquid crystal aligning agent of the present invention contains the polymer (A) and a solvent as described above, but may contain other components as necessary. Examples of such other components include other polymers other than the polymer (A), compounds having at least one epoxy group in the molecule (hereinafter referred to as “epoxy group-containing compound”), functional silane compounds, and the like. Can be mentioned.

[Other polymers]
The above other polymers can be used for improving solution properties and electrical properties. Examples of such other polymers include polyesters, polyamides, polyorganosiloxanes, cellulose derivatives, polyacetals, polystyrene derivatives, poly (styrene-phenylmaleimide) derivatives, poly (meth) acrylates, and the like. Among these, at least one polymer selected from the group consisting of polyester, polysiloxane, and poly (meth) acrylate is preferable, and polysiloxane is more preferable.

  Moreover, you may use the polymer which has a photo-alignment structure as said other polymer. Specifically, a polymer having a photoalignable group is preferable, and a polymer into which a group having a cinnamic acid structure is introduced as the photoalignable group is more preferable. Among these, a polysiloxane having a cinnamic acid structure can be preferably used because it is easy to introduce a photoalignable group into the polymer.

  In addition, the polymer which has a photoalignment group is compoundable by a conventionally well-known method. For example, the polysiloxane having a photo-alignment group is a polysiloxane having an epoxy group and a carboxylic acid having a photo-alignment group, preferably in an organic solvent such as an ether, ester, or ketone, such as a quaternary ammonium salt. It can be synthesized by reacting in the presence of a catalyst.

  Specifically, the polysiloxane can be obtained, for example, by hydrolyzing and condensing a hydrolyzable silane compound. Examples of the silane compound used for the synthesis of polysiloxane include tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3- Glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltriethoxysilane, 3- (meth) acryloxypropyltrimethoxysilane, vinyltrimethoxysilane, etc. Of these, one of these can be used alone or in combination of two or more.

  The hydrolysis / condensation reaction can be carried out by reacting one or more of the above silane compounds with water, preferably in the presence of an appropriate catalyst and an organic solvent. In the hydrolysis / condensation reaction, the proportion of water used is preferably 0.5 to 100 mol, more preferably 1 to 30 mol, per 1 mol of the silane compound (total amount).

Examples of the catalyst used in the hydrolysis / condensation reaction include acids, alkali metal compounds, organic bases, titanium compounds, zirconium compounds and the like. The amount of catalyst used varies depending on the type of catalyst, reaction conditions such as temperature, and should be set as appropriate. For example, it is preferably 0.01 to 3 times the total amount of the silane compound. More preferably, it is 0.05-1 times mole.
Examples of the organic solvent used in the above hydrolysis / condensation reaction include hydrocarbons, ketones, esters, ethers, alcohols and the like. Among these, it is preferable to use a water-insoluble or poorly water-soluble organic solvent. The use ratio of the organic solvent is preferably 10 to 10,000 parts by weight, and more preferably 50 to 1,000 parts by weight with respect to a total of 100 parts by weight of the silane compounds used in the reaction.

  The hydrolysis / condensation reaction is preferably carried out by heating with, for example, an oil bath. In the hydrolysis / condensation reaction, the heating temperature is preferably 130 ° C. or lower, more preferably 40 to 100 ° C. The heating time is preferably 0.5 to 12 hours, and more preferably 1 to 8 hours. During heating, the mixture may be stirred or placed under reflux. Moreover, after completion | finish of reaction, it is preferable to wash | clean the organic-solvent layer fractionated from the reaction liquid with water. In this washing, washing with water containing a small amount of salt (for example, an aqueous ammonium nitrate solution of about 0.2% by weight) is preferable in that the washing operation is facilitated. The washing is performed until the washed aqueous layer becomes neutral, and then the organic solvent layer is dried with a desiccant such as anhydrous calcium sulfate or molecular sieve as necessary, and then the polysiloxane is removed by removing the solvent. Can be obtained. Moreover, the polysiloxane which has a reactive group can be obtained by making the obtained polysiloxane react with a reactive compound (for example, carboxylic acid etc. which have photo-orientation group).

  The polysiloxane contained in the liquid crystal aligning agent of the present invention preferably has a polystyrene-equivalent weight average molecular weight (Mw) measured by GPC in the range of 100 to 50,000, and in the range of 200 to 10,000. It is more preferable. When the weight average molecular weight of the polysiloxane is in the above range, it is easy to handle when producing a liquid crystal alignment film, and the obtained liquid crystal alignment film has sufficient material strength and characteristics.

  When the other polymer is added to the liquid crystal aligning agent, the blending ratio is preferably 50 parts by weight or less with respect to 100 parts by weight of the total polymer in the liquid crystal aligning agent, and 0.1 to 40 parts by weight. More preferably, it is more preferably 0.1 to 30 parts by weight.

The following aspects are mentioned as a preferable aspect about the polymer component contained in the liquid crystal aligning agent of this invention.
(I) An embodiment containing only the polymer (A) as a polymer component.
(II) An embodiment in which the polymer (A) and other polymer are contained as the polymer component, and the other polymer is polysiloxane.
Among these, the aspect of said (II) is preferable at a point with favorable electrical characteristics.
When polysiloxane is contained in the liquid crystal aligning agent, the blending ratio is 0.5 to 100 parts by weight with respect to the total of 100 parts by weight of the polymer (A) from the viewpoint of sufficiently obtaining the effect of improving printability and electrical characteristics. It is preferably 90 parts by weight, more preferably 1 to 85 parts by weight, and even more preferably 3 to 80 parts 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 substrate surface. 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, neopentyl glycol diglycidyl ether, 1 , 6-hexanediol diglycidyl ether, glycerin diglycidyl ether, trimethylolpropane triglycidyl ether, 2,2-dibromoneopentyl glycol diglycidyl ether, N, N, N ′, N′-tetraglycidyl-m-xylenediamine 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, N, N, N ′, N′-tetraglycidyl-4,4′-diaminodi Enirumetan, N, N-diglycidyl - benzylamine, N, N-diglycidyl - aminomethyl cyclohexane, N, N-diglycidyl - and cyclohexyl amine.
When these epoxy compounds are added to the liquid crystal aligning agent, the blending ratio is preferably 40 parts by weight or less, more preferably 0.1 to 30 parts by weight with respect to 100 parts by weight of the total of the polymers contained in the liquid crystal aligning agent. preferable.

[Functional silane compounds]
The functional silane compound can be used for the purpose of improving the printability of the liquid crystal aligning agent. Examples of such functional silane compounds include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 2-aminopropyltrimethoxysilane, 2-aminopropyltriethoxysilane, N- (2-aminoethyl). ) -3-Aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-ureidopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, N-ethoxycarbonyl-3- Aminopropyltrimethoxysilane, N-triethoxysilylpropyltriethylenetriamine, 10-trimethoxysilyl-1,4,7-triazadecane, 9-trimethoxysilyl-3,6-diazanonyl acetate, 9-trimethoxysilyl -3,6- Methyl azananoate, N-benzyl-3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, glycidoxymethyltrimethoxysilane, 2-glycidoxyethyltrimethoxysilane, 3-glycid And xylpropyltrimethoxysilane.
When these functional silane compounds are added to the liquid crystal aligning agent, the blending ratio 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 polymer.

  The solid content concentration in the liquid crystal aligning agent of the present invention (the ratio of the total weight of components other than the solvent of the liquid crystal aligning agent to the total weight of the liquid crystal aligning agent) is appropriately selected in consideration of viscosity, volatility, and the like. The range is preferably 1 to 10% by weight. That is, the liquid crystal aligning agent of this invention is apply | coated to a substrate surface so that it may mention later, Preferably the coating film which becomes a liquid crystal aligning film or a coating film used as a liquid crystal aligning film is formed by heating. At this time, when the solid content concentration is less than 1% by weight, the film thickness of the coating film becomes too small to obtain a good liquid crystal alignment film. On the other hand, when the solid content concentration exceeds 10% by weight, it is difficult to obtain a good liquid crystal alignment film due to excessive film thickness, and the viscosity of the liquid crystal aligning agent increases, resulting in poor coating characteristics. It becomes.

  The particularly preferable range of the solid content concentration varies depending on the method used when the liquid crystal aligning agent is applied to the substrate. For example, when the spin coating method is used, a solid content concentration of 1.5 to 4.5% by weight is particularly preferable. In the case of the offset printing method, it is particularly preferable that the solid content concentration is in the range of 3 to 9% by weight and thereby the solution viscosity is in the range of 12 to 50 mPa · s. In the case of the inkjet printing method, it is particularly preferable that the solid content concentration is in the range of 1 to 8% by weight, and thereby the solution viscosity is in the range of 3 to 20 mPa · s. The temperature at the time of preparing the liquid crystal aligning agent of this invention becomes like this. Preferably it is 10-50 degreeC, More preferably, it is 20-30 degreeC.

<Liquid crystal alignment film and liquid crystal display element>
The liquid crystal alignment film of the present invention is formed by the liquid crystal aligning agent prepared as described above. Moreover, the liquid crystal display element of this invention comprises the liquid crystal aligning film formed using the liquid crystal aligning agent of this invention. The drive mode to which the liquid crystal display element of the present invention is applied is not particularly limited, and can be applied to various drive modes such as a TN type, STN type, IPS type, FFS type, VA type, and MVA type. Below, while explaining the manufacturing method of the liquid crystal display element of this invention, the manufacturing method of the liquid crystal aligning film of this invention is demonstrated in the description.

  The liquid crystal display element of the present invention can be produced, for example, by the following steps (1) to (3). In step (1), the substrate to be used varies depending on the desired drive mode. Steps (2) and (3) are common to each drive mode.

[Step (1): Formation of coating film]
First, the liquid crystal aligning agent of this invention is apply | coated on a board | substrate, Then, a coating film is formed on a board | substrate by heating an application surface.
(1-1) When manufacturing a TN type, STN type, or VA type liquid crystal display element, a pair of two substrates provided with a patterned transparent conductive film is used as a pair on the surface where each transparent conductive film is formed. The liquid crystal aligning agent of the present invention is preferably applied by an offset printing method, a spin coating method, a roll coater method or an ink jet printing method, respectively. The liquid crystal aligning agent of this invention has the advantage which can exhibit especially favorable applicability | paintability (printability), when the inkjet printing method is employ | adopted as an application | coating method.

Here, as the substrate, for example, glass such as float glass or soda glass; a transparent substrate made of plastic such as polyethylene terephthalate, polybutylene terephthalate, polyethersulfone, polycarbonate, poly (cycloaliphatic olefin) can be used. As a transparent conductive film provided on one surface of the substrate, an NESA film (registered trademark of PPG, USA) made of tin oxide (SnO ₂ ), an ITO film made of indium oxide-tin oxide (In ₂ O ₃ —SnO ₂ ), etc. Can be used. In order to obtain a patterned transparent conductive film, for example, a method of forming a pattern by photo-etching 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, etc. be able to. When applying the liquid crystal aligning agent, in order to further improve the adhesion between the substrate surface and the transparent conductive film and the coating film, a functional silane compound or functional titanium is formed on the surface of the substrate surface on which the coating film is to be formed. You may give the pretreatment which apply | coats a compound etc. previously.

  After the application of the liquid crystal aligning agent, preheating (pre-baking) is preferably performed for the purpose of preventing dripping of the applied aligning agent. The pre-baking temperature is preferably 30 to 200 ° C, more preferably 40 to 150 ° C, and particularly preferably 40 to 100 ° C. The pre-bake time is preferably 0.25 to 10 minutes, and more preferably 0.5 to 5 minutes. Thereafter, the solvent is completely removed, and if necessary, a baking (post-baking) step is performed for the purpose of thermally imidizing the amic acid structure present in the polymer. The firing (post-bake) temperature is preferably 80 to 300 ° C, more preferably 120 to 250 ° C. The post-bake time is preferably 5 to 200 minutes, more preferably 10 to 100 minutes. The thickness of the film thus formed is preferably 0.001 to 1 μm, more preferably 0.005 to 0.5 μm.

  (1-2) When manufacturing an IPS type or FFS type liquid crystal display element, an electrode forming surface of a substrate provided with an electrode made of a transparent conductive film or a metal film patterned in a comb shape, and an electrode are provided. The liquid crystal aligning agent of this invention is each apply | coated to one surface of the counter substrate which is not, and then a coating film is formed by heating each application surface. About the material of the board | substrate used at this time and a transparent conductive film, the coating method, the heating conditions after application | coating, the patterning method of a transparent conductive film or a metal film, the pre-processing of a board | substrate, and the preferable film thickness of the coating film formed are the said ( It is the same as 1-1). As the metal film, for example, a film made of a metal such as chromium can be used.

  In both cases (1-1) and (1-2), after applying the liquid crystal aligning agent on the substrate, the organic solvent is removed to form a coating film that becomes the alignment film. At this time, when the polymer contained in the liquid crystal aligning agent of the present invention is a polyamic acid, a polyamic acid ester, or an imidized polymer having an imide ring structure and an amic acid structure Further, after the coating film is formed, the film may be further heated to cause the dehydration ring-closing reaction to proceed so that the coating film is more imidized.

[Step (I-2): Orientation ability imparting treatment]
When manufacturing a TN type, STN type, IPS type, or FFS type liquid crystal display element, the coating film formed in the step (I-1) is subjected to a treatment for imparting liquid crystal alignment ability. Thereby, the orientation ability of a liquid crystal molecule is provided to a coating film, and it becomes a liquid crystal aligning film. Examples of the treatment for imparting liquid crystal alignment ability include rubbing treatment in which a coating film is rubbed in a fixed direction with a roll wound with a cloth made of fibers such as nylon, rayon, and cotton, and polarized or non-polarized radiation is applied to the coating film. Examples include photo-alignment treatment for irradiation. On the other hand, when manufacturing a VA type liquid crystal display element, the coating film formed in the step (I-1) can be used as it is as a liquid crystal alignment film, but the coating film is subjected to an alignment ability imparting treatment. May be.

In the photo-alignment treatment, ultraviolet rays and visible rays including light having a wavelength of 150 to 800 nm can be used as radiation applied to the coating film, for example. When the radiation is polarized light, it may be linearly polarized light or partially polarized light. When the radiation used is linearly polarized light or partially polarized light, irradiation may be performed from a direction perpendicular to the substrate surface, an oblique direction, or a combination thereof. When non-polarized radiation is irradiated, the irradiation direction is an oblique direction.
As a light source to be used, for example, a low-pressure mercury lamp, a high-pressure mercury lamp, a deuterium lamp, a metal halide lamp, an argon resonance lamp, a xenon lamp, an excimer laser, or the like can be used. Ultraviolet rays in a preferable wavelength region can be obtained by means of using a light source in combination with, for example, a filter or a diffraction grating. The radiation dose is preferably 100 to 50,000 J / m ² , more preferably 300 to 20,000 J / m ² . Moreover, you may perform light irradiation with respect to a coating film, heating a coating film, in order to improve the reactivity. The temperature at the time of heating is 30-250 degreeC normally, Preferably it is 40-200 degreeC, More preferably, it is 50-150 degreeC.

  In addition, the liquid crystal alignment film after the rubbing treatment is further subjected to a treatment for changing the pretilt angle of a part of the liquid crystal alignment film by irradiating a part of the liquid crystal alignment film with ultraviolet rays, After forming a resist film in part, perform a rubbing process in a direction different from the previous rubbing process and then remove the resist film, so that the liquid crystal alignment film has different liquid crystal alignment capabilities for each region. Also good. In this case, it is possible to improve the visibility characteristics of the obtained liquid crystal display element. A liquid crystal alignment film suitable for a VA liquid crystal display element can also be suitably used for a PSA (Polymer sustained alignment) type liquid crystal display element.

[Step (3): Construction of liquid crystal cell]
Two substrates on which the liquid crystal alignment film is formed as described above are prepared, and a liquid crystal cell is manufactured by disposing a liquid crystal between the two substrates disposed to face each other. In order to manufacture a liquid crystal cell, the following two methods are mentioned, for example.
The first method is a conventionally known method. First, two substrates are arranged to face each other through a gap (cell gap) so that the respective liquid crystal alignment films face each other, and the peripheral portions of the two substrates are bonded together using a sealant, and the substrate surface and the sealant A liquid crystal cell can be manufactured by injecting and filling liquid crystal into the cell gap partitioned by the above, and then sealing the injection hole. The second method is a method called an ODF (One Drop Fill) method. For example, an ultraviolet light curable sealant is applied to a predetermined location on one of the two substrates on which the liquid crystal alignment film is formed, and liquid crystal is dropped at predetermined locations on the liquid crystal alignment film surface. After that, the other substrate is bonded so that the liquid crystal alignment film faces, and the liquid crystal is spread over the entire surface of the substrate, and then the entire surface of the substrate is irradiated with ultraviolet light to cure the sealant, thereby manufacturing a liquid crystal cell. can do. Regardless of which method is used, the liquid crystal cell produced as described above is further heated to a temperature at which the liquid crystal used takes an isotropic phase and then gradually cooled to room temperature. It is desirable to remove.

As the sealing agent, for example, an epoxy resin containing a curing agent and aluminum oxide spheres as a spacer can be used.
Examples of the liquid crystal include nematic liquid crystal and smectic liquid crystal. Among them, nematic liquid crystal is preferable. For example, Schiff base liquid crystal, azoxy liquid crystal, biphenyl liquid crystal, phenylcyclohexane liquid crystal, ester liquid crystal, terphenyl liquid crystal, biphenyl. Cyclohexane liquid crystals, pyrimidine liquid crystals, dioxane liquid crystals, bicyclooctane liquid crystals, cubane liquid crystals, and the like can be used. Further, cholesteric liquid crystals such as cholestyl chloride, cholesteryl nonate, and cholesteryl carbonate; chiral agents such as those sold under the trade names “C-15” and “CB-15” (manufactured by Merck & Co., Inc.). A ferroelectric liquid crystal such as p-decyloxybenzylidene-p-amino-2-methylbutylcinnamate may be added and used.

  And the liquid crystal display element of this invention can be obtained by bonding a polarizing plate on the outer surface of a liquid crystal cell. As a polarizing plate to be bonded to the outer surface of the liquid crystal cell, a polarizing film or an H film itself in which a polarizing film called an “H film” in which iodine is absorbed while stretching and aligning polyvinyl alcohol is sandwiched between cellulose acetate protective films The polarizing plate which consists of can be mentioned. When the rubbing treatment is performed on the coating film, the two substrates are arranged to face each other so that the rubbing directions in each coating film are at a predetermined angle, for example, orthogonal or antiparallel.

  The liquid crystal display element of the present invention can be effectively applied to various devices such as a desk calculator, wristwatch, table clock, mobile phone, counting display board, word processor, personal computer, liquid crystal television, portable game, car navigation. It can be used for display devices such as systems, camcorders, PDAs, digital cameras, smartphones, and various monitors.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

[Weight average molecular weight of polymer]
The weight average molecular weight Mw is a polystyrene equivalent value measured by gel permeation chromatography under the following conditions.
Column: Tosoh Co., Ltd., TSKgelGRCXLII
Solvent: Tetrahydrofuran Temperature: 40 ° C
Pressure: 68 kgf / cm ²
[Solution viscosity of polymer solution]
The solution viscosity [mPa · s] of the polymer solution was measured at 25 ° C. using an E-type rotational viscometer for a solution prepared to a polymer concentration of 10% by weight using a predetermined solvent.
In addition, the required amount of the raw material compound and the polymer used in the following examples was ensured by repeating the synthesis of the raw material compound and the polymer on the synthetic scale shown in the following synthesis examples as necessary.

[Synthesis of polyamic acid]
[Synthesis Example 1]
2,3,5-tricarboxycyclopentyl acetic acid dianhydride 112 g (0.50 mol) and 1,3,3a, 4,5,9b-hexahydro-8-methyl-5- (tetrahydro) as tetracarboxylic dianhydride -2,5-dioxo-3-furanyl) -naphtho [1,2-c] -furan-1,3-dione 157 g (0.50 mol) and p-phenylenediamine 95 g (0.88 mol) as the diamine compound ), 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl 32 g (0.10 mol), 3,6-bis (4-aminobenzoyloxy) cholestane 6.4 g (0.010 mol) ) And 4.0 g (0.015 mol) of octadecanoxy-2,5-diaminobenzene are dissolved in 960 g of N-methyl-2-pyrrolidone and reacted at 60 ° C. for 9 hours. It was. A small amount of the obtained polyamic acid solution (PA-1) was collected, N-methyl-2-pyrrolidone was added, and the solution viscosity measured as a solution having a concentration of 10% by weight was 58 mPa · s.

[Synthesis of polyorganosiloxane having epoxy group]
[Synthesis Example 2]
In a reaction vessel equipped with a stirrer, thermometer, dropping funnel and reflux condenser, 100.0 g of 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane (ECETS), 500 g of methyl isobutyl ketone and 10.0 g of triethylamine were added. Charged and mixed at room temperature. Next, 100 g of deionized water was dropped from the dropping funnel over 30 minutes, and the mixture was reacted at 80 ° C. for 6 hours while mixing under reflux. After completion of the reaction, the organic layer is taken out and washed with a 0.2 wt% aqueous ammonium nitrate solution until the water after washing becomes neutral, and then the solvent and water are distilled off under reduced pressure, whereby a polyorgano having an epoxy group is obtained. Siloxane was obtained as a viscous clear liquid.

[Synthesis of photoalignable polyorganosiloxane]
[Synthesis Example 3]
In a 100 mL three-necked flask, 9.3 g of the polyorganosiloxane having an epoxy group obtained in Synthesis Example 2 above, 26 g of methyl isobutyl ketone, 3 g of the following cinnamic acid derivative (K-1) and a trade name “UCAT 18X” (San Apro Co., Ltd.) ) A quaternary amine salt manufactured in.) 0.10 g was charged and stirred at 80 ° C. for 12 hours. After completion of the reaction, reprecipitation with methanol was performed, and the precipitate was dissolved in ethyl acetate to obtain a solution. This solution was washed with water three times, and then the solvent was distilled off to remove the photoalignable polyorganosiloxane compound (S -1) was obtained as a white powder. The photoalignable polyorganosiloxane compound (S-1) had a weight average molecular weight Mw of 3,500.

[Synthesis Example 4]
(Synthesis of Compound (K-2))

  To a 100 mL eggplant flask equipped with a reflux tube and a nitrogen introduction tube, 4.63 g of compound (A-1), 50 mL of thionyl chloride and 0.05 mL of N, N-dimethylformamide were added and refluxed for 1 hour. After completion of the reaction, the mixture was concentrated to dryness under reduced pressure, and then 75 mL of tetrahydrofuran was added (referred to as (A-2) solution). On the other hand, to a 100 mL three-necked flask equipped with a thermometer and a nitrogen introduction tube, 2.62 g of 4-hydroxycinnamic acid, 4.41 g of potassium carbonate, 38 mL of water, 19 mL of tetrahydrofuran and 0.15 g of tetrabutylammonium bromide were added to bring the temperature to 5 ° C. or lower. Ice-cooled. Subsequently, the previously prepared (Liquid A-2) was added dropwise over 30 minutes, and then returned to room temperature and stirred for 4 hours. After completion of the reaction, 100 mL of ethyl acetate and 200 mL of 1N hydrochloric acid were added for washing, followed by separation and washing with 100 mL of water three times. Next, the organic layer was dried over magnesium sulfate, filtered, concentrated under reduced pressure, and the precipitated white crystals were filtered and dried, yielding 1.8 g of compound (K-2).

[Synthesis Example 5]
(Synthesis of Compound (K-3))

  A 300 mL three-necked flask containing a stirrer was charged with 5.09 g of lithium chloride and 1.64 g of zinc chloride and purged with nitrogen. 120 ml of ethylenemagnesium chloride-tetrahydrofuran 1 mol / L solution was added thereto, stirred at room temperature for 1 hour, cooled to 0 ° C., 12.6 g of cyclooctanone was added dropwise thereto, and reacted at room temperature for 15 hours. (It shall be (A-5) liquid). Then, saturated ammonium chloride aqueous solution was dripped at the (A-5) liquid while ice bathing, and 300 mL of ethyl acetate was added. The organic layer was separated and washed with 300 mL of water three times, and then the organic layer was dried over magnesium sulfate. Then, 11.7g of compounds (A-3) were obtained by distilling a solvent off by concentration by a rotary evaporator and distilling a residue.

  In a 300 mL three-necked flask containing a stirrer, 10.9 g of the compound (A-3) was placed and placed in an ice bath at 0 ° C. Then, 134 mL of n-butyllithium-hexane 1.6 mol / L solution was dropped and stirred at 0 ° C. for 20 minutes, and then a solution of 13.9 g of methyl 4- (chlorocarbonyl) benzoate dissolved in 30 mL of tetrahydrofuran was added. The solution was added dropwise and stirred at 0 ° C. for 2 hours. Thereto, 5 mL of water was added dropwise, and 200 mL of ethyl acetate was added. The organic layer was separated and washed with 300 mL of water three times, and then the organic layer was dried over magnesium sulfate. Then, 13.4g of compounds (A-4) were obtained by concentration by a rotary evaporator.

  To a 100 mL three-necked flask containing a stirrer was added 9.55 g of compound (A-4), 30 g of methanol, 10 g of water, and 2.52 g of lithium hydroxide monohydrate, and the mixture was stirred for 1 hour at room temperature. 50 mL of ethyl acetate was added to the liquid. The organic layer was separated and washed once with 10 mL of diluted hydrochloric acid and 3 times with 50 mL of water, and then the organic layer was dried over magnesium sulfate. Then, it concentrated by the rotary evaporator and concentrated slowly until the internal volume became 20g, and the white solid which precipitated on the way was collect | recovered by filtration. This white solid was vacuum-dried to obtain 5.5 g of compound (K-3).

[Synthesis Example 6]
In a 100 mL three-necked flask, 9.3 g of polyorganosiloxane having an epoxy group obtained in Synthesis Example 2 above, 26 g of methyl isobutyl ketone, 5.8 g of Compound (K-2) obtained in Synthesis Example 4 above, and the trade name “UCAT” 18X "(a quaternary amine salt manufactured by San Apro Co., Ltd.) was charged, and the mixture was stirred at 80 ° C for 12 hours. After completion of the reaction, reprecipitation with methanol was performed, and the precipitate was dissolved in ethyl acetate to obtain a solution. This solution was washed with water three times, and then the solvent was distilled off to remove the photoalignable polyorganosiloxane compound (S -2) was obtained as white powder. The weight-average molecular weight Mw of the photoalignable polyorganosiloxane compound (S-2) was 3,600.

[Synthesis Example 7]
In a 100 mL three-necked flask, 9.3 g of the polyorganosiloxane having an epoxy group obtained in Synthesis Example 2 above, 26 g of methyl isobutyl ketone, 5.8 g of (K-2) obtained in Synthesis Example 4 above, and in Synthesis Example 5 above 1.8 g of the obtained (K-3) and 0.10 g of a trade name “UCAT 18X” (a quaternary amine salt manufactured by San Apro Co., Ltd.) were charged and stirred at 80 ° C. for 12 hours. After completion of the reaction, reprecipitation with methanol was performed, and the precipitate was dissolved in ethyl acetate to obtain a solution. This solution was washed with water three times, and then the solvent was distilled off to remove the photoalignable polyorganosiloxane compound (S -3) was obtained as white powder. The weight-average molecular weight Mw of the photoalignable polyorganosiloxane compound (S-3) was 3,500.

[Example 1]
To the polyamic acid solution (PA-1) obtained in Synthesis Example 1, 8 parts by weight of the photoalignable polyorganosiloxane (S-1) obtained in Synthesis Example 3 is added to 100 parts by weight of the polyamic acid, Further, N-methyl-2-pyrrolidone and diethylene glycol isopropyl methyl ether were added, and the solvent composition was N-methyl-2-pyrrolidone: diethylene glycol isopropyl methyl ether = 30: 70 (weight ratio) and a solid content concentration of 3.0% did. This was filtered through a filter having a pore size of 0.2 μm and subjected to the following evaluation.

<Evaluation of inkjet coating properties>
As a substrate on which the liquid crystal aligning agent is applied, a glass substrate with a transparent electrode made of ITO is heated on a hot plate at 200 ° C. for 1 minute, and then subjected to ultraviolet / ozone cleaning, so that the contact angle of water on the transparent electrode surface is 10 The one immediately after setting the temperature below was used.
The liquid crystal aligning agent prepared above (after filtration) was applied onto the transparent electrode surface of the glass substrate with the transparent electrode using an inkjet coating machine (manufactured by Shibaura Mechatronics Co., Ltd.). The coating conditions at this time were 2,500 times / (nozzle / minute), and two reciprocations (total four times) at a discharge amount of 250 mg / 10 seconds. The coating film having an average film thickness of 0.1 μm was formed by heating after standing for 1 minute after coating. The obtained coating film was observed with the naked eye under irradiation of an interference fringe measuring lamp (sodium lamp) to evaluate unevenness and repellency. The heating temperature is 50 ° C., 60 ° C., and 80 ° C. When neither unevenness nor repellency is observed at any temperature, the ink-jet coating property is “good A (）)”, and unevenness and / or repellency is achieved at one heating temperature. “Good B (◯)” when unevenness is seen, “Yes (△)” when unevenness and / or repellency is seen at two heating temperatures, and unevenness and / or repellency is seen at all heating temperatures In the case of “bad (×)”. The ink-jet coating property of the liquid crystal aligning agent of this example was “good B (◯)”.

<Manufacture of liquid crystal cells>
A liquid crystal cell for evaluating liquid crystal orientation and voltage holding ratio was produced as follows. In the production of the liquid crystal cell, the liquid crystal aligning agent was applied by a spin coating method, which is to enable comparison with a comparative example described later, which is inferior in ink jet coatability.

The liquid crystal aligning agent prepared above (after filtration) is applied by spin coating on the transparent electrode surface of the glass substrate with a transparent electrode made of an ITO film, pre-baked on an 80 ° C. hot plate for 1 minute, and then A coating film having an average film thickness of 0.1 μm was formed by post-baking on a hot plate at 200 ° C. for 10 minutes. The same operation was repeated to produce a pair (two) of substrates having a coating film on the transparent conductive film. Thereafter, the substrate surface on the side having the coating film is irradiated with polarized ultraviolet rays of 1,000 J / m ² from a direction perpendicular to the substrate surface using a Hg-Xe lamp and a Grand Taylor prism, and a liquid crystal having a film thickness of 0.1 μm. A pair of substrates having an alignment film was obtained.
After applying an epoxy resin adhesive containing aluminum oxide spheres having a diameter of 5.5 μm to each outer edge of the pair of substrates having the liquid crystal alignment film, the liquid crystal alignment film surfaces are stacked and pressure-bonded so as to face each other. Cured. Next, a nematic liquid crystal (MLC-6601, manufactured by Merck & Co., Inc.) was filled between the pair of substrates from the liquid crystal inlet, and then the liquid crystal inlet was sealed with an acrylic photo-curing adhesive to produce a liquid crystal cell. .

<Evaluation of voltage holding ratio>
A voltage of 5 V was applied to the liquid crystal cell obtained above with an application time of 60 microseconds and a span of 167 milliseconds, and then the voltage holding ratio after 167 milliseconds from release of application was measured. The measuring apparatus used was VHR-1 manufactured by Toyo Corporation. When this value is 95% or more, the voltage holding ratio is “good A (）)”, and when it is less than 95% and 93% or more, the voltage holding ratio “good B (◯)” is less than 93%. The voltage holding ratio was “good (Δ)”, and the case where the evaluation was impossible was evaluated as “bad (×)”. The voltage holding ratio of the liquid crystal cell of this example was “good (◎)”. there were.

[Examples 2 to 11 and Comparative Examples 1 to 4 and Comparative Example 6]
In the above Example 1, a liquid crystal aligning agent was prepared and various evaluations were performed in the same manner as in Example 1 except that the polymers and solvents shown in Table 1 below were used. The evaluation results are shown in Table 1 below.
[Example 12 and Comparative Example 5]
In Example 1 above, except that the polymer and the solvent were each of the type and amount shown in Table 1 below, and that the rubbing treatment was performed instead of the photo-alignment treatment in the production of the liquid crystal cell. In the same manner as in Example 1, a liquid crystal aligning agent was prepared and various evaluations were performed. The rubbing treatment was performed using a rubbing machine having a roll around which a nylon cloth was wound, at a roll rotation speed of 1,000 rpm, a stage moving speed of 25 mm / sec, and a hair foot pushing length of 0.4 mm. The evaluation results are shown in Table 1 below.

In Table 1, the abbreviations of the compounds have the following meanings.
IPDM: Diethylene glycol isopropyl methyl ether BDM: Diethylene glycol n-butyl methyl ether NMP: N-methyl-2-pyrrolidone BC: Butyl cellosolve DPM: Dipropylene glycol monomethyl ether DEDG: Diethylene glycol diethyl ether

  As shown in Table 1, in each of Examples 1 to 12, the printability and the voltage holding ratio by the inkjet coating method were evaluated as “good A (◎)” or “good B (◯)”. On the other hand, in the comparative example, at least one of the printability by the ink jet coating method and the voltage holding ratio was inferior to that of the example.

Claims (3)

A liquid crystal aligning agent comprising at least one polymer (A) selected from the group consisting of polyamic acid, polyimide and polyamic acid ester, and a solvent,
The solvent contains at least one selected from the group consisting of diethylene glycol propyl methyl ether and diethylene glycol butyl methyl ether ;
Furthermore, the liquid crystal aligning agent characterized by including the polysiloxane which has a photo-alignment group . The liquid crystal aligning film formed using the liquid crystal aligning agent of Claim 1 . A liquid crystal display device comprising the liquid crystal alignment film according to claim 2 .