JP7509286B2 - Liquid crystal alignment agent - Google Patents

Description

The present invention relates to a liquid crystal alignment agent.

Conventionally, various driving methods have been developed for liquid crystal elements, with different electrode structures and physical properties of the liquid crystal molecules used. For example, various types of liquid crystal elements are known, such as TN type, STN type, VA type, in-plane switching type (IPS type), FFS type, and optically compensated bent type (OCB type). These liquid crystal elements have a liquid crystal alignment film for orienting the liquid crystal molecules. Polyamic acid and polyimide are used as materials for the liquid crystal alignment film, as they have good properties such as heat resistance, mechanical strength, and affinity with liquid crystal.

In liquid crystal alignment agents, the polymer components are dissolved in a solvent, and a liquid crystal alignment film is formed by applying the liquid crystal alignment agent to a substrate and heating it. Here, organic solvents in which the polymer is highly soluble, such as aprotic polar solvents such as N-methyl-2-pyrrolidone and γ-butyrolactone, are generally used as the solvent for the liquid crystal alignment agent. In addition, in order to improve the coatability (printability) of the liquid crystal alignment agent when it is applied to a substrate, an organic solvent with a relatively low surface tension, such as butyl cellosolve, is used in combination with the aprotic polar solvent (see, for example, Patent Document 1 and Patent Document 2).

The liquid crystal alignment agent can be applied to a substrate by a variety of methods, including spin coating, offset printing, and inkjet printing. For example, offset printing is generally performed by applying the liquid crystal alignment agent to a printing plate made of a resin such as APR (registered trademark), and using a transfer printing device to transfer the liquid crystal alignment agent onto the substrate by the printing plate (see, for example, Patent Document 3).

JP 2010-97188 A JP 2010-156934 A JP 2001-343649 A

Butyl cellosolve, which is commonly used to improve the coatability of liquid crystal alignment agents, tends to easily swell APR resin. Therefore, when a liquid crystal alignment agent containing butyl cellosolve is applied to a substrate by offset printing, there is a concern that repeated application to the printing plate will cause the printing plate to swell, resulting in a decrease in printability. In addition, the solvent component of the liquid crystal alignment agent is required to be such that polymers are unlikely to precipitate on the printing machine even when printing is performed continuously, and to have good printability (continuous printability).

The present invention has been made in consideration of the above problems, and one of its objectives is to provide a liquid crystal alignment agent that is less likely to cause swelling of the printing plate and has good printability.

As a result of intensive research into solving the problems of the conventional technology as described above, the inventors discovered that the above problems could be solved by using a specific organic solvent as a solvent, and thus completed the present invention. Specifically, the present invention provides the following liquid crystal alignment agent.

（式（３）中、Ｒ^７～Ｒ^１０は、それぞれ独立に、水素原子又は１価の有機基である。） In one aspect, the present invention provides a liquid crystal aligning agent comprising a polymer component and a specific solvent, the specific solvent being a compound represented by the following formula (3):

(In formula (3), R ⁷ to R ¹⁰ are each independently a hydrogen atom or a monovalent organic group.)

By using the above-mentioned specific solvent as the solvent component of the liquid crystal alignment agent, it is possible to obtain a liquid crystal alignment agent that is less likely to cause swelling of the printing plate. In addition, even when printing is performed continuously, polymers are less likely to precipitate on the printing machine, making it possible to improve printability.

The liquid crystal alignment film of the present invention is formed using a liquid crystal alignment agent containing the above-mentioned specific solvent, so that a uniform coating film can be formed and the film quality is good. Furthermore, when a liquid crystal element is manufactured using the above-mentioned liquid crystal alignment agent, printing defects can be reduced in the manufacturing process, resulting in improved product yield.

Below, we will explain each component contained in the liquid crystal alignment agent of the present invention, as well as other components that can be added as needed.

<Polymer Component>
The liquid crystal alignment agent of the present invention contains a polymer component. The main backbone of the polymer is not particularly limited, and examples thereof include the main backbone of polyamic acid, polyamic acid ester, polyimide, polysiloxane, polyester, polyamide, polybenzoxazole precursor, polybenzoxazole, cellulose derivative, polyacetal, polystyrene derivative, poly(styrene-phenylmaleimide) derivative, poly(meth)acrylate, etc. Here, (meth)acrylate means to include acrylate and methacrylate.

In terms of the high effect of improving printability by the specific solvent, it is preferable that the polymer component of the liquid crystal alignment agent is at least one selected from the group consisting of polyamic acid, polyamic acid ester, polyimide, and polyorganosiloxane. In addition, when preparing the liquid crystal alignment agent, one type of polymer may be used alone, or two or more types may be used in combination.

[Polyamic acid]
The polyamic acid in the present invention can be obtained, for example, by reacting a tetracarboxylic dianhydride with a diamine.

(Tetracarboxylic acid dianhydride)
Examples of the tetracarboxylic dianhydride used in the synthesis of the polyamic acid include aliphatic tetracarboxylic dianhydrides, alicyclic tetracarboxylic dianhydrides, aromatic tetracarboxylic dianhydrides, etc. Specific examples of these include aliphatic tetracarboxylic dianhydrides such as 1,2,3,4-butanetetracarboxylic dianhydride;
Examples of alicyclic tetracarboxylic dianhydrides include 1,2,3,4-cyclobutane tetracarboxylic dianhydride, 1,3-dimethyl-1,2,3,4-cyclobutane tetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentylacetic dianhydride, 1,3,3a,4,5,9b-hexahydro-5-(tetrahydro-2,5-dioxo-3-furanyl)-naphtho[1,2-c]furan-1,3-dione, 1,3,3a,4,5,9b-hexahydro-8-methyl-5-(tetrahydro-2,5-dioxo-3-furanyl)-naphtho[1, 2-c]furan-1,3-dione, 3-oxabicyclo[3.2.1]octane-2,4-dione-6-spiro-3'-(tetrahydrofuran-2',5'-dione), 5-(2,5-dioxotetrahydro-3-furanyl)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride, 3,5,6-tricarboxy-2-carboxymethylnorbornane-2:3,5:6-dianhydride, 2,4,6,8-tetracarboxybicyclo[3.3.0]octane-2:4,6:8-dianhydride, 4,9-dioxatricyclo[5.3.1.0 ^2,6 ]undecane-3,5,8,10-tetraone, cyclohexanetetracarboxylic dianhydride, and the like;
Examples of aromatic tetracarboxylic dianhydrides include pyromellitic dianhydride and the like; in addition, the tetracarboxylic dianhydrides described in JP-A-2010-97188 can be used. The tetracarboxylic dianhydrides can be used alone or in combination of two or more.

The tetracarboxylic dianhydride used in the synthesis is preferably one containing an alicyclic tetracarboxylic dianhydride, in that it can improve electrical properties, and can increase the solubility of the polymer in solvents including specific solvents, thereby improving printability. Among the alicyclic tetracarboxylic dianhydrides, 2,3,5-tricarboxycyclopentylacetic 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. It is preferable that the dianhydride contains at least one selected from the group consisting of 2,3,5-tricarboxycyclopentylacetic acid dianhydride, 2,4,6,8-tetracarboxybicyclo[3.3.0]octane-2:4,6:8-dianhydride, and 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride, and it is particularly preferable that the dianhydride contains at least one selected from the group consisting of 2,3,5-tricarboxycyclopentylacetic acid dianhydride, 2,4,6,8-tetracarboxybicyclo[3.3.0]octane-2:4,6:8-dianhydride, and 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride.

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

(Diamine)
Examples of diamines used in the synthesis of polyamic acid include aliphatic diamines, alicyclic diamines, aromatic diamines, diaminoorganosiloxanes, etc. Specific examples of these diamines include aliphatic diamines such as metaxylylenediamine, 1,3-propanediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, 1,3-bis(aminomethyl)cyclohexane, etc.; alicyclic diamines such as 1,4-diaminocyclohexane, 4,4'-methylenebis(cyclohexylamine), etc.;

（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。 Examples of aromatic diamines include p-phenylenediamine, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl sulfide, 1,5-diaminonaphthalene, 2,2'-dimethyl-4,4'-diaminobiphenyl, 4,4'-diamino-2,2'-bis(trifluoromethyl)biphenyl, 4,4'-diaminodiphenyl ether, 1,3-bis(4-aminophenoxy)propane, 9,9-bis(4-aminophenyl)fluorene, 2,2-bis[4-(4-aminophenoxy)phenyl]phenyl]propane, 1,3-bis(4-aminophenyl)propane, 1,3-bis(4-aminophenyl)fluorene, 1,3-bis(4-aminophenyl)phenyl]propane ... nyl]hexafluoropropane, 4,4'-(p-phenylenediisopropylidene)bisaniline, 1,4-bis(4-aminophenoxy)benzene, 2,6-diaminopyridine, 3,6-diaminocarbazole, N,N'-bis(4-aminophenyl)-benzidine, 1,4-bis-(4-aminophenyl)-piperazine, 1-(4-aminophenyl)-2,3-dihydro-1,3,3-trimethyl-1H-inden-5-amine, 1-(4-aminophenyl)-2,3-dihydro-1,3,3-trimethyl-1H-inden-5-amine, Methyl-1H-inden-6-amine, 3,5-diaminobenzoic acid, cholestanyloxy-3,5-diaminobenzene, cholestenyloxy-3,5-diaminobenzene, cholestanyloxy-2,4-diaminobenzene, cholestanyl 3,5-diaminobenzoate, cholestanyl 3,5-diaminobenzoate, lanostannyl 3,5-diaminobenzoate, 3,6-bis(4-aminobenzoyloxy)cholestane, 4-(4'-trifluoromethoxybenzoyloxy)cyclohexyl-3,5-diaminobenzyl benzoate, 1,1-bis(4-((aminophenyl)methyl)phenyl)-4-heptylcyclohexane, 1,1-bis(4-((aminophenyl)methyl)phenyl)-4-(4-heptylcyclohexyl)cyclohexane, 2,4-diamino-N,N-diallylaniline, 4-aminobenzylamine, N-[4-(2-aminoethyl)phenyl]benzene-1,4-diamine, N-[4-(aminomethyl)phenyl]benzene-1,4-diamine, cinnamic acid structure-containing diamines and the following formula (D-1),

(In formula (D-1), X ^I and X ^II each independently represent a single bond, -O-, *-COO-, *-OCO-, or *-NH-CO- (the bond marked with "*" is bonded to a diaminophenyl group), R ^I and R ^II each independently represent an alkanediyl group having 1 to 3 carbon atoms, a is 0 or 1, b is an integer from 0 to 2, c is an integer from 1 to 20, n is 0 or 1, and m is 0 or 1. However, a and b cannot be 0 at the same time, and when X ^I is *-NH-CO-, n is 0.)
Compounds represented by the formula:
Examples of diaminoorganosiloxanes include 1,3-bis(3-aminopropyl)-tetramethyldisiloxane, and the diamines described in JP-A-2010-97188 can also be used. These diamines can be used alone or in combination of two or more.

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

The diamines used in the synthesis of polyamic acid preferably contain 30 mol% or more of aromatic diamines relative to the total diamines, more preferably 50 mol% or more, and particularly preferably 80 mol% or more.

(Synthesis of polyamic acid)
Polyamic acid can be obtained by reacting the above-mentioned tetracarboxylic dianhydride with a diamine, together with a molecular weight modifier, if necessary. The ratio of the tetracarboxylic dianhydride and the diamine used in the synthesis reaction of polyamic acid is preferably such that the acid anhydride group of the tetracarboxylic dianhydride is 0.2 to 2 equivalents per equivalent of the amino group of the diamine. Examples of the molecular weight modifier include acid monoanhydrides such as maleic anhydride, phthalic anhydride, and itaconic anhydride, monoamine compounds such as aniline, cyclohexylamine, and n-butylamine, and monoisocyanate compounds such as phenyl isocyanate and naphthyl isocyanate. The ratio of the molecular weight modifier used is preferably 20 parts by weight or less per 100 parts by weight of the total of the tetracarboxylic dianhydride and diamine used.

The synthesis reaction of the polyamic acid is preferably carried out in an organic solvent, preferably at a reaction temperature of -20°C to 150°C, and for a reaction time of 0.1 to 24 hours.
Examples of the organic solvent used in the reaction include aprotic polar solvents, phenolic solvents, alcohols, ketones, esters, ethers, halogenated hydrocarbons, and hydrocarbons. Particularly preferred organic solvents include one or more selected from the group consisting of N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, dimethylsulfoxide, γ-butyrolactone, tetramethylurea, hexamethylphosphortriamide, m-cresol, xylenol, halogenated phenols, and the specific solvents shown below, or a mixture of one or more of these with other organic solvents (e.g., butyl cellosolve, diethylene glycol diethyl ether, etc.). The amount (a) of the organic solvent used is preferably an amount such that the total amount (b) of the tetracarboxylic dianhydride and the diamine is 0.1 to 50% by weight based on the total amount (a+b) of the reaction solution.
In this manner, a reaction solution in which polyamic acid is dissolved is obtained. This reaction solution may be used as it is for the preparation of a liquid crystal aligning agent, or the polyamic acid contained in the reaction solution may be isolated and then used for the preparation of a liquid crystal aligning agent.

[Polyimide]
The polyimide of the present invention can be obtained by dehydrating and cyclizing the polyamic acid synthesized as described above to convert it into an imidized product. The polyimide may be a fully imidized product in which all of the amic acid structures of the polyamic acid precursor are dehydrated and cyclized, or a partially imidized product in which only a portion of the amic acid structures are dehydrated and cyclized, and in which the amic acid structure and the imide ring structure coexist. The polyimide of the present invention preferably has an imidization rate of 30% or more, more preferably 40 to 99%, and even more preferably 50 to 99%. This imidization rate is the ratio of the number of imide ring structures to the total number of amic acid structures and the number of imide ring structures of the polyimide, expressed as a percentage. Here, some of the imide rings may be isoimide rings.

The dehydration and ring-closing of the polyamic acid is preferably carried out by heating the polyamic acid or by dissolving the polyamic acid in an organic solvent, adding a dehydrating agent and a dehydration and ring-closing catalyst to the solution, and heating as necessary. Of these, the latter method is preferred.
In the method of adding a dehydrating agent and a dehydration ring-closing catalyst to a solution of a 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 used is preferably 0.01 to 20 moles per mole of the amic acid structure of the polyamic acid. The amount of the dehydration ring-closing catalyst used is preferably 0.01 to 10 moles per mole of the dehydrating agent used. The organic solvent used in the dehydration ring-closing reaction can be the organic solvents exemplified as those used in the synthesis of polyamic acid. The reaction temperature of the dehydration ring-closing reaction is preferably 0 to 180° C., and the reaction time is preferably 1.0 to 120 hours.

In this way, a reaction solution containing polyimide is obtained. This reaction solution may be used as is for the preparation of a liquid crystal alignment agent, or may be used for the preparation of a liquid crystal alignment agent after removing the dehydrating agent and the dehydration ring-closing catalyst from the reaction solution, or may be used for the preparation of a liquid crystal alignment agent after isolating the polyimide. These purification operations can be performed according to known methods. In addition, polyimide can also be obtained by imidizing a polyamic acid ester.

[Polyamic acid ester]
The polyamic acid ester of the present invention can be obtained, for example, by a method such as [I] reacting the polyamic acid obtained by the above synthesis reaction with an esterifying agent (e.g., methanol, ethanol, N,N-dimethylformamide diethyl acetal, etc.), [II] reacting a tetracarboxylic acid diester with a diamine in an organic solvent in the presence of a suitable dehydration catalyst (e.g., 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium halide, a phosphorus-based condensing agent, etc.), or [III] reacting a tetracarboxylic acid diester dihalide with a diamine in an organic solvent in the presence of a suitable base (e.g., pyridine, triethylamine, sodium hydroxide, etc.).
The polyamic acid ester contained in the liquid crystal aligning agent 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 in which the polyamic acid ester is dissolved may be used for preparing the liquid crystal aligning agent as it is, or the polyamic acid ester contained in the reaction solution may be isolated and then used for preparing the liquid crystal aligning agent.

The polyamic acid, polyamic acid ester, and polyimide obtained as described above preferably have a solution viscosity of 10 to 800 mPa·s, and more preferably 15 to 500 mPa·s, when made into a 10% by weight solution. The solution viscosity (mPa·s) of the polymer is a value measured at 25° C. using an E-type rotational viscometer for a 10% by weight polymer solution prepared using a good solvent for the polymer (e.g., γ-butyrolactone, N-methyl-2-pyrrolidone, etc.).
The polyamic acid, polyamic acid ester, and polyimide contained in the liquid crystal aligning agent of the present invention preferably have a weight average molecular weight in terms of polystyrene measured by gel permeation chromatography (GPC) of 500 to 100,000, more preferably 1,000 to 50,000.

[Polyorganosiloxane]
The polyorganosiloxane of the present invention can be obtained, for example, by hydrolyzing or hydrolyzing and condensing a hydrolyzable silane compound, preferably in the presence of a suitable organic solvent, water and a catalyst.

Examples of hydrolyzable silane compounds used in the synthesis of polyorganosiloxane include alkoxysilane compounds such as tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, trimethoxysilylpropylsuccinic anhydride, dimethyldimethoxysilane, and dimethyldiethoxysilane; 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, mercaptomethyltrimethoxysilane, mercaptomethyltriethoxysilane, 3-ureidopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-(3-cyclohexylamino)propyl ... )propyltrimethoxysilane and other nitrogen- and sulfur-containing alkoxysilane compounds; 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane and other epoxy group-containing silane compounds; 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropylmethyldimethoxysilane, 3-(meth)acryloxypropylmethyldiethoxysilane, vinyltrimethoxysilane, p-styryltrimethoxysilane and other unsaturated bond-containing alkoxysilane compounds. The hydrolyzable silane compounds may be used alone or in combination of two or more of these. Note that "(meth)acryloxy" includes "acryloxy" and "methacryloxy".

The hydrolysis and condensation reaction is carried out by reacting one or more of the above-mentioned silane compounds with water, preferably in the presence of a suitable catalyst and an organic solvent. In the reaction, the proportion of water used is preferably 1 to 30 moles per mole of the silane compounds (total amount). Examples of the catalyst used include acids, alkali metal compounds, organic bases (e.g., triethylamine and tetramethylammonium hydroxide), titanium compounds, and zirconium compounds. The amount of catalyst used varies depending on the type of catalyst, reaction conditions such as temperature, and should be set appropriately, but is preferably 0.01 to 3 moles per the total amount of silane compounds. Examples of organic solvents used include hydrocarbons, ketones, esters, ethers, and alcohols, and among these, it is preferable to use a water-insoluble or poorly water-soluble organic solvent. The proportion of the organic solvent used is preferably 50 to 1,000 parts by weight per 100 parts by weight of the total silane compounds used in the reaction.

The above hydrolysis and condensation reaction is preferably carried out by heating, for example, in an oil bath. In this case, the heating temperature is preferably 130°C or less, and the heating time is preferably 0.5 to 12 hours. After the reaction is completed, the organic solvent layer is separated from the reaction solution, and the solvent is removed to obtain polysiloxane.

When applied to a liquid crystal alignment agent for TN-type, STN-type or vertical alignment type liquid crystal display elements, a specific group such as a liquid crystal alignment group or a group having a photoalignment structure may be introduced into the side chain of the polyorganosiloxane. The method for synthesizing a polyorganosiloxane having such a specific group in the side chain is not particularly limited, but examples include a method in which an epoxy group-containing silane compound or a mixture of an epoxy group-containing silane compound and another silane compound is hydrolyzed and condensed to synthesize a polyorganosiloxane having an epoxy group, and then the obtained epoxy group-containing polyorganosiloxane is reacted with a carboxylic acid having the above-mentioned specific group. The reaction between the epoxy group-containing polyorganosiloxane and the carboxylic acid can be carried out according to a known method.

The polyorganosiloxane preferably has a weight average molecular weight (Mw) in terms of polystyrene measured by GPC in the range of 500 to 100,000, more preferably in the range of 1,000 to 30,000, and even more preferably in the range of 1,000 to 20,000. When the weight average molecular weight of the polyorganosiloxane 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 properties.

In the liquid crystal alignment agent of the present invention, the content ratio of the polymer selected from the group consisting of polyamic acid, polyamic acid ester, polyimide and polyorganosiloxane (the total amount when two or more types are contained) is preferably 50% by weight or more, more preferably 60% by weight or more, based on the total amount of the polymer components in the liquid crystal alignment agent. In addition, from the viewpoint of more suitably obtaining the effects of the present invention, it is preferable that the polymer component contains at least one selected from the group consisting of polyamic acid, polyamic acid ester and polyimide. The total content ratio of polyamic acid, polyamic acid ester and polyimide in the liquid crystal alignment agent is preferably 40% by weight or more, more preferably 60% by weight or more, based on the total amount of the polymer components in the liquid crystal alignment agent.

<Solvent>
The liquid crystal aligning agent of the present invention is a liquid composition in which a polymer component is dispersed or dissolved in a solvent. The liquid crystal aligning agent contains, as a solvent, at least one specific solvent selected from the group consisting of a solvent having a phosphorus atom (hereinafter also referred to as a "phosphorus-containing solvent"), N,N'-dimethylpropylene urea, tetrahydro-4H-pyran-4-one, tetramethylene sulfoxide, 3-methylcyclohexanone, 4-methylcyclohexanone, a compound represented by the following formula (1), a compound represented by the following formula (2), a compound represented by the following formula (3), and a compound represented by the following formula (10).

（式（１）中、Ｒ^４は、水素原子又は炭素数１～６のアルキル基である。式（２）中、Ｒ^５は、水素原子又は炭素数１～６のアルキル基であり、Ｒ^６は、炭素数２～４のアルカンジイル基である。式（３）中、Ｒ^７～Ｒ^１０は、それぞれ独立に、水素原子又は１価の有機基である。式（１０）中、Ｒ^１１～Ｒ^１３は、それぞれ独立に、水素原子又は炭素数１～３のアルキル基である。）

(In formula (1), R ⁴ is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. In formula (2), R ⁵ is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and R ⁶ is an alkanediyl group having 2 to 4 carbon atoms. In formula (3), R ⁷ to R ¹⁰ are each independently a hydrogen atom or a monovalent organic group. In formula (10), R ¹¹ to R ¹³ are each independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.)

（式（ｐ－１）～（ｐ－４）中、Ｘ^１及びＹ^１は、それぞれ独立に酸素原子又は硫黄原子である。Ｒ^１は、水素原子又は炭素数１～１０の１価の炭化水素基であり、Ｒ^２は、水素原子又は１価の有機基である。ただし、Ｒ^１とＲ^２とが相互に結合して環を形成していてもよい。Ｒ^３は、それぞれ独立に水素原子又は炭素数１～６のアルキル基であり、窒素原子に結合する２個のＲ^３が相互に結合して窒素原子とともに１価の窒素含有複素環基を形成していてもよい。ただし、Ｒ^１及びＲ^２は同時に水素原子にならず、Ｒ^２及びＲ^３は同時に水素原子にならない。ｍ，ｎ，ｋ及びｊは、それぞれ独立に１～３の整数である。ｍ，ｎ，ｋ，ｊが２又は３の場合、式中の複数のＲ^１，Ｒ^３は互いに同じでも異なってもよく、ｍ，ｎ，ｋ，ｊが１の場合、式中の複数のＲ^２は互いに同じでも異なってもよい。） [Phosphorus-containing solvent]
The phosphorus-containing solvent is not particularly limited as long as it is a compound having at least one phosphorus atom in the molecule, but is preferably at least one selected from the group consisting of compounds represented by each of the following formulas (p-1) to (p-4).

(In formulae (p-1) to (p-4), X ¹ and Y ¹ are each independently an oxygen atom or a sulfur atom. R ¹ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms, and R ² is a hydrogen atom or a monovalent organic group. However, R ¹ and R ² may be bonded to each other to form a ring. R ³ is each independently a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and two R ^3s bonded to a nitrogen atom may be bonded to each other to form a monovalent nitrogen-containing heterocyclic group together with the nitrogen atom. However, R ¹ and R ² are not hydrogen atoms at the same time, and R ² and R ³ are not hydrogen atoms at the same time. m, n, k, and j are each independently an integer of 1 to 3. When m, n, k, and j are 2 or 3, multiple R ^1s and R ^3s in the formula may be the same or different from each other, and when m, n, k, and j are 1, multiple R ^2s in the formula may be the same or different from each other.)

Here, in this specification, the term "hydrocarbon group" includes chain-shaped hydrocarbon groups, alicyclic hydrocarbon groups, and aromatic hydrocarbon groups. The term "chain-shaped hydrocarbon group" means a straight-chain hydrocarbon group and a branched hydrocarbon group that do not include a ring structure in the main chain and are composed only of a chain structure. However, they may be saturated or unsaturated. The term "alicyclic hydrocarbon group" means a hydrocarbon group that contains only an alicyclic hydrocarbon structure as a ring structure and does not contain an aromatic ring structure. However, it does not have to be composed only of an alicyclic hydrocarbon structure, and it also includes those that have a chain structure as a part of it. The term "aromatic hydrocarbon group" means a hydrocarbon group that contains an aromatic ring structure as a ring structure. However, it does not have to be composed only of an aromatic ring structure, and it may contain a chain structure or an alicyclic hydrocarbon structure as a part of it. In addition, in this specification, the term "organic group" means a group that contains carbon atoms, and may contain heteroatoms in the structure.

In the above formula (p-1), examples of the monovalent hydrocarbon group having 1 to 10 carbon atoms for R ¹ include linear or branched alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, and decyl groups; alkenyl groups such as vinyl and allyl groups; alkynyl groups such as ethynyl groups; cycloalkyl groups such as cyclopentyl, cyclohexyl, and methylcyclohexyl groups; aryl groups such as phenyl, tolyl, and xylyl groups; and aralkyl groups such as benzyl, phenethyl, and styryl groups. Of these, R ¹ is preferably an alkyl group having 1 to 3 carbon atoms.

Examples of the monovalent organic group for ^R2 include monovalent hydrocarbon groups having 1 to 10 carbon atoms, groups containing a heteroatom-containing group between the carbon-carbon bond of the hydrocarbon group, groups in which the hydrocarbon group and a heteroatom-containing group are bonded, groups in which at least one hydrogen atom of these groups has been replaced with a substituent, a cyano group, and a formyl group.
Here, the heteroatom-containing group means a divalent or higher group having a heteroatom, and examples thereof include -O-, -CO-, -COO-, -CONR ^a - (R ^a is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, the same applies below), -NR ^a -, a trivalent nitrogen atom, -NR ^a CONR ^a -, -OCONR ^a -, -S-, -COS-, -OCOO-, -SO ₂ -, and the like. Examples of the substituent include a halogen atom, a nitro group, a cyano group, a hydroxyl group, and the like. Among the above, ^{R 2} is preferably an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 or 7 carbon atoms.

The alkyl group having 1 to 6 carbon atoms of R ³ may be linear or branched. The monovalent nitrogen-containing heterocyclic group formed by mutually bonding two R ^3s includes a group obtained by removing a hydrogen atom bonded to a nitrogen atom of a nitrogen-containing heterocyclic ring. Specific examples of the nitrogen-containing heterocyclic ring include a pyrrolidine ring and a piperidine ring, and the ring portion may have a substituent such as a halogen atom or an alkyl group. R ³ is preferably an alkyl group having 1 to 3 carbon atoms, more preferably a methyl group. X ¹ and Y ¹ are preferably oxygen atoms. m, n, k, and j are preferably 2 or 3, more preferably 3.

As the phosphorus-containing solvent, from the viewpoint of a higher effect of improving printability, it is preferable to use at least one selected from the group consisting of the compound represented by formula (p-1) and the compound represented by formula (p-3) among the above formulas (p-1) to (p-4), and it is more preferable to use the compound represented by formula (p-1).

Preferred specific examples of the phosphorus-containing solvent include the compounds represented by the following formulae (p-1-1) to (p-1-7), (p-3-1) and (p-3-2).

As the phosphorus-containing solvent, the compounds represented by the above formulas (p-1-1) to (p-1-4) and (p-3-1) are particularly preferred among the above because they have better printability. The phosphorus-containing solvents can be used alone or in combination of two or more.

[Compound represented by the above formula (1)]
In the above formula (1), examples of the alkyl group having 1 to 6 carbon atoms for R ⁴ include a methyl group, an ethyl group, a propyl group, a butyl group, etc., which may be linear or branched. Specific examples of the compound represented by the above formula (1) include 4-formylmorpholine, 4-acetylmorpholine, etc., and among these, 4-formylmorpholine is particularly preferred. The compounds represented by the above formula (1) may be used alone or in combination of two or more.

[Compound represented by the above formula (2)]
In the above formula (2), examples of the alkyl group having 1 to 6 carbon atoms for R ⁵ can be the same as those for R ⁴ in the above formula (1). Examples of the alkanediyl group having 2 to 4 carbon atoms for R ⁶ include an ethylene group, a propanediyl group, and a butanediyl group, which may be linear or branched. Specific examples of the compound represented by the above formula (2) include 3-methyl-2-oxazolidone, 3-ethyl-2-oxazolidone, 3-isopropyl-2-oxazolidone, and N-methyl-2-oxazinanone, and among these, 3-methyl-2-oxazolidone is particularly preferred. The compounds represented by the above formula (2) can be used alone or in combination of two or more.

[Compound represented by the above formula (3)]
In the above formula (3), examples of the monovalent organic group of R ⁷ to R ¹⁰ include an alkyl group having 1 to 10 carbon atoms, a group containing a heteroatom-containing group between the carbon-carbon bond of the alkyl group, a group in which the alkyl group and a heteroatom-containing group are bonded, and a group in which at least one hydrogen atom of these groups is replaced with a substituent. Specific examples of the heteroatom-containing group and the substituent can be applied to the explanation of R ² in the above formula (p-1). R ⁷ to R ¹⁰ may be the same or different from each other. R ⁷ to R ¹⁰ are preferably a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or -COR ^b (R ^b is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms). It is preferable that one of R ⁷ and R ¹⁰ is -COR ^b .

Specific examples of the compound represented by the above formula (3) include, for example, 2-furaldehyde, 3-furaldehyde, 5-methyl-2-furaldehyde, 5-methyl-3-furaldehyde, 4-methyl-2-furaldehyde, 4-methyl-2-furaldehyde, 5-hydroxymethyl-2-furaldehyde, etc., of which 5-methyl-2-furaldehyde is particularly preferred. The compounds represented by the above formula (3) can be used alone or in combination of two or more.

[Compound represented by the above formula (10)]
In the above formula (10), examples of the alkyl group having 1 to 3 carbon atoms for R ¹¹ to R ¹³ include a methyl group, an ethyl group, an n-propyl group, and an isopropyl group, among which a methyl group is preferred. Specific examples of the compound represented by the above formula (10) include lactamide, N,N-dimethyl lactamide, N,N-diethyl lactamide, N-methyl-N-propyl lactamide, N-ethyl lactamide, and N-isopropyl lactamide, among which N,N-dimethyl lactamide is particularly preferred. The compounds represented by the above formula (10) can be used alone or in combination of two or more.

As the specific solvent, from among the above, at least one selected from the group consisting of phosphorus-containing solvents, N,N'-dimethylpropylene urea, the compound represented by the above formula (1), and the compound represented by the above formula (2) is preferred, since it has better printability (particularly continuous printability). Note that the specific solvent can be used alone or in combination of two or more.

[Other solvents]
The liquid crystal alignment agent of the present invention may contain a solvent other than the specific solvent (hereinafter, also referred to as "other solvent"). Specific examples of other solvents include N-ethyl-2-pyrrolidone, N-(n-propyl)-2-pyrrolidone, N-isopropyl-2-pyrrolidone, N-(n-butyl)-2-pyrrolidone, N-(t-butyl)-2-pyrrolidone, N-(n-pentyl)-2-pyrrolidone, N-methoxypropyl-2-pyrrolidone, N-ethoxyethyl-2-pyrrolidone, N-methoxybutyl-2-pyrrolidone, 3-butoxy-N,N-dimethylpropanamide, 3 ... -N,N-dimethylpropanamide, 3-hexyloxy-N,N-dimethylpropanamide, isopropoxy-N-isopropyl-propionamide, n-butoxy-N-isopropyl-propionamide, 1,3-dimethyl-2-imidazolidinone, tetramethylurea, N-methyl-2-pyrrolidone, γ-butyrolactone, δ-valerolactone, γ-valerolactone, γ-caprolactone, N,N-diethylacetamide, γ-butyrolactam, N,N-di Examples of the solvent include methylformamide, N,N-dimethylacetamide, 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-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, diethylene glycol monoethyl ether acetate, dipropylene glycol monomethyl ether (DPM), diisobutyl ketone, isoamyl propionate, isoamyl isobutyrate, ethylene carbonate, and propylene carbonate. As for the other solvents, the above-mentioned ones can be used alone or in combination of two or more.

Regarding the specific solvent, all of the solvents contained in the liquid crystal alignment agent may be specific solvents, or only a portion of them may be specific solvents. The content ratio of the specific solvents (the total amount when two or more types are used, the same applies below) is preferably 1 to 80% by weight, more preferably 5 to 70% by weight, even more preferably 10 to 60% by weight, and particularly preferably 20 to 60% by weight, based on the total amount of the solvents contained in the liquid crystal alignment agent.

<Other ingredients>
The liquid crystal aligning agent of the present invention contains the polymer component and the solvent as described above, but may contain other components as necessary. Examples of such other components include compounds having at least one epoxy group in the molecule, functional silane compounds, photopolymerizable compounds, surfactants, fillers, defoamers, sensitizers, dispersants, antioxidants, adhesion aids, antistatic agents, leveling agents, antibacterial agents, etc. The blending ratio of these can be appropriately set according to the compound to be blended within a range that does not impair the effects of the present invention.

The solid content concentration in the liquid crystal alignment agent of the present invention (the ratio of the total weight of the components other than the solvent of the liquid crystal alignment agent to the total weight of the liquid crystal alignment agent) is appropriately selected taking into consideration viscosity, volatility, etc., but is preferably in the range of 1 to 10% by weight. That is, the liquid crystal alignment agent of the present invention is applied to the surface of a substrate as described below, and preferably heated to form a coating film that is a liquid crystal alignment film or a coating film that will become a liquid crystal alignment film. At this time, if the solid content concentration is less than 1% by weight, the thickness of the coating film becomes too small, making it difficult to obtain a good liquid crystal alignment film. On the other hand, if the solid content concentration exceeds 10% by weight, the thickness of the coating film becomes too large, making it difficult to obtain a good liquid crystal alignment film, and the viscosity of the liquid crystal alignment agent increases, tending to deteriorate the coating characteristics.

The particularly preferred range of solid content varies depending on the method used to apply the liquid crystal alignment agent to the substrate. For example, when using the spin coating method, a solid content range of 1.5 to 4.5% by weight is particularly preferred. When using the offset printing method, it is particularly preferred that the solid content range be 3 to 9% by weight, thereby resulting in a solution viscosity in the range of 12 to 50 mPa·s. When using the inkjet method, it is particularly preferred that the solid content range be 1 to 5% by weight, thereby resulting in a solution viscosity in the range of 3 to 15 mPa·s. The temperature at which the liquid crystal alignment agent is prepared is preferably 10 to 50°C, more preferably 20 to 30°C.

<Liquid crystal alignment film and liquid crystal element>
The liquid crystal alignment film of the present invention is formed by the liquid crystal alignment agent prepared as described above. The liquid crystal element of the present invention includes a liquid crystal alignment film formed by using the liquid crystal alignment agent. The driving mode of the liquid crystal in the liquid crystal element is not particularly limited, and it can be applied to various driving modes such as TN type, STN type, IPS type, FFS type, VA type, MVA type, and PSA type. The liquid crystal element of the present invention can be manufactured by a method including, for example, the following steps 1 to 3. In step 1, the substrate used differs depending on the desired driving mode. Steps 2 and 3 are common to each driving mode.

[Step 1: Formation of coating film]
First, the liquid crystal aligning agent of the present invention is applied onto a substrate, and then the applied surface is heated to form a coating film on the substrate.
(1-1) When manufacturing a TN type, STN type, VA type, MVA type or PSA type liquid crystal element, two substrates each having a patterned transparent conductive film are used as a pair, and a liquid crystal alignment agent is applied to the transparent conductive film-formed surface of each substrate, preferably by offset printing, spin coating, roll coater or inkjet printing. As the substrate, for example, a transparent substrate made of glass such as float glass or soda glass; or a plastic such as polyethylene terephthalate, polybutylene terephthalate, polyethersulfone, polycarbonate or poly(alicyclic olefin) can be used. As the transparent conductive film provided on one side of the substrate, a 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 ) or the like can be used.

After the liquid crystal alignment agent is applied, pre-heating (pre-baking) is preferably performed to prevent dripping of the applied alignment agent. The pre-baking temperature is preferably 30 to 200°C, and the pre-baking time is preferably 0.25 to 10 minutes. After that, a baking (post-baking) step is performed to completely remove the solvent and, if necessary, to thermally imidize the amic acid structure present in the polymer. The baking temperature (post-baking temperature) at this time is preferably 80 to 300°C, and the post-baking time is preferably 5 to 200 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, a liquid crystal alignment agent is applied to the electrode-forming surface of a substrate on which an electrode made of a transparent conductive film or metal film patterned into a comb-tooth shape is provided, and to one surface of an opposing substrate on which no electrode is provided, and then each applied surface is heated to form a coating film. The materials of the substrate and transparent conductive film used here, the coating method, the heating conditions after coating, the film thickness, etc. are the same as those in (1-1) above. As the metal film, for example, a film made of a metal such as chromium can be used.
In either case of (1-1) or (1-2) above, a liquid crystal alignment film or a coating film to become a liquid crystal alignment film is formed by applying a liquid crystal alignment agent onto a substrate and then removing the organic solvent.

[Step 2: Treatment for imparting alignment ability]
When a TN-type, STN-type, IPS-type or FFS-type liquid crystal display element is manufactured, a treatment is carried out to impart liquid crystal alignment ability to the coating film formed in the above step 1. This imparts the alignment ability of liquid crystal molecules to the coating film, forming a liquid crystal alignment film. Examples of the alignment ability imparting treatment include a rubbing treatment in which the coating film is rubbed in a certain direction with a roll wrapped with a cloth made of fibers such as nylon, rayon or cotton, and a photoalignment treatment in which the coating film is irradiated with polarized or non-polarized radiation. On the other hand, when a VA-type liquid crystal display element is manufactured, the coating film formed in the above step 1 can be used as a liquid crystal alignment film as it is, but the coating film may also be subjected to an alignment ability imparting treatment. The liquid crystal alignment film suitable for a VA-type 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 liquid crystal is disposed between the two substrates arranged opposite to each other to manufacture a liquid crystal cell. For example, the liquid crystal cell can be manufactured by (1) arranging two substrates opposite to each other with a gap therebetween so that the liquid crystal alignment film faces each other, bonding the peripheries of the two substrates together using a sealant, injecting liquid crystal into the substrate surface and the cell gap partitioned by the sealant, and then sealing the injection hole, or (2) applying a sealant to a predetermined location on one substrate on which the liquid crystal alignment film is formed, dropping liquid crystal into a few predetermined locations on the liquid crystal alignment film surface, bonding the other substrate so that the liquid crystal alignment film faces each other, and spreading the liquid crystal over the entire surface of the substrate (ODF method). It is desirable to further heat the manufactured liquid crystal cell to a temperature at which the liquid crystal used has an isotropic phase, and then slowly cool it to room temperature to remove the flow orientation during liquid crystal filling.

As the sealing agent, for example, an epoxy resin containing a hardener and aluminum oxide spheres as spacers can be used. As the liquid crystal, nematic liquid crystal and smectic liquid crystal can be mentioned, among which nematic liquid crystal is preferable, and for example, Schiff base liquid crystal, azoxy liquid crystal, biphenyl liquid crystal, phenylcyclohexane liquid crystal, ester liquid crystal, terphenyl liquid crystal, biphenylcyclohexane liquid crystal, pyrimidine liquid crystal, dioxane liquid crystal, bicyclooctane liquid crystal, cubane liquid crystal, etc. can be used. In addition, for example, cholesteric liquid crystal, chiral agent, ferroelectric liquid crystal, etc. can be added to these liquid crystals.

When manufacturing a PSA type liquid crystal display element, a liquid crystal cell is constructed in the same manner as above, except that a photopolymerizable compound is injected or dropped together with the liquid crystal. Then, the liquid crystal cell is irradiated with light while a DC or AC voltage is applied between the conductive films of the pair of substrates. Also, when a coating film is formed on a substrate using a liquid crystal alignment agent containing a photopolymerizable compound, a liquid crystal cell is constructed in the same manner as above, and then a liquid crystal element may be manufactured by going through a process of irradiating the liquid crystal cell with light while a DC or AC voltage is applied between the conductive films of the pair of substrates.

Then, by laminating a polarizing plate on the outer surface of the liquid crystal cell, the liquid crystal display element of the present invention can be obtained. Examples of the polarizing plate to be laminated on the outer surface of the liquid crystal cell include a polarizing film called an "H film" made by absorbing iodine while stretching and aligning polyvinyl alcohol, sandwiched between cellulose acetate protective films, and a polarizing plate made of the H film itself.

The liquid crystal element of the present invention can be effectively applied to various devices, for example, various display devices such as clocks, portable games, word processors, notebook computers, car navigation systems, camcorders, PDAs, digital cameras, mobile phones, smartphones, various monitors, and liquid crystal televisions, as well as light control films. In addition, the liquid crystal element formed using the liquid crystal alignment agent of the present invention can also be applied to retardation films.

The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples.

The solution viscosity of each polymer solution, the imidization rate of polyimide, the weight average molecular weight, and the epoxy equivalent in the synthesis examples were measured by the following methods.
[Solution Viscosity of Polymer Solution (mPa·s)] A solution prepared by adjusting the polymer concentration to 10% by weight using a prescribed solvent was measured at 25° C. using an E-type rotational viscometer.
[Imidization rate of polyimide] A polyimide solution was poured into pure water, and the resulting precipitate was thoroughly dried under reduced pressure at room temperature, then dissolved in deuterated dimethyl sulfoxide and subjected to ^1H -NMR measurement at room temperature using tetramethylsilane as a standard substance. From the obtained ^1H -NMR spectrum, the imidization rate [%] was calculated using the following formula (1).
Imidization rate [%] = (1 - ^A1 / ^A2 x α) x 100 ... (1)
(In formula (1), ^A1 is the peak area derived from the NH group proton appearing at a chemical shift of about 10 ppm, ^A2 is the peak area derived from other protons, and α is the ratio of the number of other protons to one NH group proton in the polymer precursor (polyamic acid).)
[Weight average molecular weight Mw of polymer] This is a polystyrene equivalent value measured by gel permeation chromatography under the following conditions.
Column: TSKgel GRCXLII, manufactured by Tosoh Corporation
Solvent: Tetrahydrofuran Temperature: 40°C
Pressure: 68 kgf/ ^cm2
[Epoxy equivalent] Measured by the hydrochloric acid-methyl ethyl ketone method described in JIS C 2105.

<Synthesis of Polymer>
[Synthesis Example 1: Synthesis of polyimide (PI-1)]
22.4 g (0.1 mol) of 2,3,5-tricarboxycyclopentylacetic dianhydride (TCA) as a tetracarboxylic dianhydride, 8.6 g (0.08 mol) of p-phenylenediamine (PDA) as a diamine, and 10.5 g (0.02 mol) of cholestanyl 3,5-diaminobenzoate (HCDA) as a diamine were dissolved in 166 g of N-methyl-2-pyrrolidone (NMP) and reacted at 60° C. for 6 hours to obtain a solution containing 20% by weight of polyamic acid. A small amount of the obtained polyamic acid solution was taken, and NMP was added to make a solution with a polyamic acid concentration of 10% by weight. The solution viscosity was measured and found to be 90 mPa·s.
Next, NMP was added to the obtained polyamic acid solution to obtain a solution with a polyamic acid concentration of 7% by weight, and 11.9 g of pyridine and 15.3 g of acetic anhydride were added to perform a dehydration ring-closing reaction at 110° C. for 4 hours. After the dehydration ring-closing reaction, the solvent in the system was replaced with fresh NMP (by this operation, the pyridine and acetic anhydride used in the dehydration ring-closing reaction were removed from the system. The same applies below.), thereby obtaining a solution containing 26% by weight of polyimide (PI-1) with an imidization rate of about 68%. A small amount of the obtained polyimide solution was taken, and NMP was added to obtain a solution with a polyimide concentration of 10% by weight. The solution viscosity was measured and was 45 mPa·s. Next, the reaction solution was poured into a large excess of methanol to precipitate the reaction product. The precipitate was washed with methanol and dried at 40° C. under reduced pressure for 15 hours to obtain polyimide (PI-1).

[Synthesis Example 2: Synthesis of polyimide (PI-2)]
22.5 g (0.1 mol) of TCA as a tetracarboxylic dianhydride, 7.6 g (0.07 mol) of PDA as a diamine, 5.2 g (0.01 mol) of HCDA, and 4.0 g (0.02 mol) of 4,4'-diaminodiphenylmethane (DDM) were dissolved in 157 g of NMP and reacted at 60°C for 6 hours to obtain a solution containing 20% by weight of polyamic acid. A small amount of the obtained polyamic acid solution was taken and NMP was added to make a solution with a polyamic acid concentration of 10% by weight, and the solution viscosity was measured to be 110 mPa·s.
Next, NMP was added to the obtained polyamic acid solution to obtain a solution with a polyamic acid concentration of 7% by weight, and 16.6 g of pyridine and 21.4 g of acetic anhydride were added to perform a dehydration ring-closing reaction at 110° C. for 4 hours. After the dehydration ring-closing reaction, the solvent in the system was replaced with fresh NMP to obtain a solution containing 26% by weight of polyimide (PI-2) with an imidization rate of about 82%. A small amount of the obtained polyimide solution was taken, and NMP was added to obtain a solution with a polyimide concentration of 10% by weight. The solution viscosity was measured to be 62 mPa·s. Next, the reaction solution was poured into a large excess of methanol to precipitate the reaction product. The precipitate was washed with methanol and dried at 40° C. under reduced pressure for 15 hours to obtain polyimide (PI-2).

[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-dianhydride (BODA) as a tetracarboxylic dianhydride, 8.6 g (0.08 mol) of PDA as a diamine, and 10.4 g (0.02 mol) of HCDA were dissolved in 176 g of NMP and reacted at 60° C. for 6 hours to obtain a solution containing 20% by weight of polyamic acid. A small amount of the obtained polyamic acid solution was taken and NMP was added to make a solution with a polyamic acid concentration of 10% by weight, and the solution viscosity was measured to be 103 mPa·s.
Next, NMP was added to the obtained polyamic acid solution to obtain a solution with a polyamic acid concentration of 7% by weight, and 11.9 g of pyridine and 15.3 g of acetic anhydride were added to perform a dehydration ring-closing reaction at 110° C. for 4 hours. After the dehydration ring-closing reaction, the solvent in the system was replaced with fresh NMP to obtain a solution containing 26% by weight of polyimide (PI-3) with an imidization rate of about 71%. A small amount of the obtained polyimide solution was taken, and NMP was added to obtain a solution with a polyimide concentration of 10% by weight. The solution viscosity was measured and was 57 mPa·s. Next, the reaction solution was poured into a large excess of methanol to precipitate the reaction product. The precipitate was washed with methanol and dried at 40° C. under reduced pressure for 15 hours to obtain polyimide (PI-3).

[Synthesis Example 4: Synthesis of polyimide (PI-4)]
As tetracarboxylic dianhydrides, 110 g (0.50 mol) of TCA and 160 g (0.50 mol) of 1,3,3a,4,5,9b-hexahydro-8-methyl-5-(tetrahydro-2,5-dioxo-3-furanyl)naphtho[1,2-c]furan-1,3-dione, as diamines, 91 g (0.85 mol) of PDA, 25 g (0.10 mol) of 1,3-bis(3-aminopropyl)tetramethyldisiloxane and 25 g (0.040 mol) of 3,6-bis(4-aminobenzoyloxy)cholestane, as well as 1.4 g (0.015 mol) of aniline as a monoamine, were dissolved in 960 g of NMP and reacted at 60° C. for 6 hours to obtain a solution containing a polyamic acid. A small amount of the obtained polyamic acid solution was taken, and NMP was added to make a solution having a polyamic acid concentration of 10% by weight. The solution viscosity was measured and found to be 60 mPa·s.
Next, 2,700 g of NMP was added to the obtained polyamic acid solution, and 390 g of pyridine and 410 g of acetic anhydride were added to carry out a dehydration ring-closing reaction at 110° C. for 4 hours. After the dehydration ring-closing reaction, the solvent in the system was replaced with fresh γ-butyrolactone to obtain about 2,500 g of a solution containing 15% by weight of polyimide (PI-4) with an imidization rate of about 95%. A small amount of this solution was taken, and NMP was added to obtain a solution with a polyimide concentration of 10% by weight. The solution viscosity was measured to be 70 mPa·s. Next, the reaction solution was poured into a large excess of methanol to precipitate the reaction product. The precipitate was washed with methanol and dried at 40° C. under reduced pressure for 15 hours to obtain polyimide (PI-4).

[Synthesis Example 5: Synthesis of polyimide (PI-5)]
22.4 g (0.1 mol) of TCA as a tetracarboxylic dianhydride, 8.6 g (0.08 mol) of PDA as a diamine, 2.0 g (0.01 mol) of DDM, and 3.2 g (0.01 mol) of 4,4'-diamino-2,2'-bis(trifluoromethyl)biphenyl were dissolved in 324 g of NMP and reacted at 60°C for 4 hours to obtain a solution containing 10% by weight of polyamic acid.
Next, 360 g of NMP was added to the obtained polyamic acid solution, and 39.5 g of pyridine and 30.6 g of acetic anhydride were added to carry out a dehydration ring-closing reaction at 110° C. for 4 hours. After the dehydration ring-closing reaction, the solvent in the system was replaced with fresh NMP to obtain a solution containing 10% by weight of polyimide (PI-5) with an imidization rate of about 93%. A small amount of the obtained polyimide solution was taken and the solution viscosity was measured to be 30 mPa·s. Next, the reaction solution was poured into a large excess of methanol to precipitate the reaction product. The precipitate was washed with methanol and dried under reduced pressure at 40° C. for 15 hours to obtain polyimide (PI-5).

[Synthesis Example 6: Synthesis of polyimide (PI-6)]
Except for changing the diamines used to 0.08 mol of 3,5-diaminobenzoic acid (3,5DAB) and 0.02 mol of cholestanyloxy-2,4-diaminobenzene (HCODA), a polyamic acid solution was obtained in the same manner as in Synthesis Example 1. A small amount of the obtained polyamic acid solution was taken and NMP was added to make a solution with a polyamic acid concentration of 10 wt %, and the solution viscosity was measured to be 80 mPa·s.
Next, imidization was carried out in the same manner as in Synthesis Example 1 above, to obtain a solution containing 26% by weight of polyimide (PI-6) with an imidization rate of about 65%. A small amount of the obtained polyimide solution was taken, and NMP was added to make a solution with a polyimide concentration of 10% by weight, and the solution viscosity was measured to be 40 mPa·s. Next, the reaction solution was poured into a large excess of methanol to precipitate the reaction product. The precipitate was washed with methanol and dried under reduced pressure at 40° C. for 15 hours to obtain polyimide (PI-6).

[Synthesis Example 7: Synthesis of polyamic acid (PA-1)]
200 g (1.0 mol) of 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CB) as a tetracarboxylic dianhydride and 210 g (1.0 mol) of 2,2'-dimethyl-4,4'-diaminobiphenyl as a diamine were dissolved in a mixed solvent of 370 g of NMP and 3,300 g of γ-butyrolactone, and the mixture was reacted at 40°C for 3 hours to obtain a polyamic acid solution having a solid content concentration of 10% by weight and a solution viscosity of 160 mPa·s. Next, this polyamic acid solution was poured into a large excess of methanol to precipitate the reaction product. The precipitate was washed with methanol and dried under reduced pressure at 40°C for 15 hours to obtain polyamic acid (PA-1).

[Synthesis Example 8: Synthesis of polyamic acid (PA-2)]
A polyamic acid solution having a solid content concentration of 10% by weight and a solution viscosity of 170 mPa·s was obtained by the same method as in Synthesis Example 7 above, except that the tetracarboxylic dianhydride used was 0.9 mol of pyromellitic dianhydride (PMDA) and 0.1 mol of CB, and the diamine used was 0.2 mol of PDA and 0.8 mol of 4,4′-diaminodiphenyl ether (DDE). Next, this polyamic acid solution was poured into a large excess of methanol to precipitate the reaction product. The precipitate was washed with methanol and dried under reduced pressure at 40° C. for 15 hours to obtain polyamic acid (PA-2).

[Synthesis Example 9: Synthesis of polyamic acid (PA-3)]
7.0 g (0.031 mol) of TCA as a tetracarboxylic dianhydride and 13 g of a compound represented by the following formula (R-1) as a diamine (corresponding to 1 mol per mol of TCA) were dissolved in 80 g of NMP and reacted at 60° C. for 4 hours to obtain a solution containing 20% by weight of polyamic acid (PA-3). The solution viscosity of this polyamic acid solution was 2,000 mPa·s. The compound represented by the following formula (R-1) was synthesized according to the description of JP-A-2011-100099. Next, this polyamic acid solution was poured into a large excess of methanol to precipitate the reaction product. The precipitate was washed with methanol and dried at 40° C. under reduced pressure for 15 hours to obtain polyamic acid (PA-3).

[Synthesis Example 10: Synthesis of polyorganosiloxane (APS-1)]
In a reaction vessel equipped with a stirrer, a thermometer, a dropping funnel and a 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 charged and mixed at room temperature. Next, 100 g of deionized water was dropped from the dropping funnel over 30 minutes, and then the reaction was carried out at 80 ° C. for 6 hours while stirring under reflux. After the reaction was completed, the organic layer was taken out and washed with a 0.2 wt% aqueous ammonium nitrate solution until the water after washing became neutral, and then the solvent and water were distilled off under reduced pressure to obtain a reactive polyorganosiloxane (EPS-1) as a viscous transparent liquid. When ¹ H-NMR analysis was performed on this reactive polyorganosiloxane (EPS-1), a peak based on the epoxy group was obtained at a chemical shift (δ) of about 3.2 ppm according to the theoretical intensity, and it was confirmed that no side reaction of the epoxy group occurred during the reaction. The weight average molecular weight Mw of the resulting reactive polyorganosiloxane was 3,500 and the epoxy equivalent was 180 g/mol.
Next, 10.0 g of reactive polyorganosiloxane (EPS-1), 30.28 g of methyl isobutyl ketone as a solvent, 3.98 g of 4-dodecyloxybenzoic acid as a reactive compound, and 0.10 g of UCAT 18X (trade name, manufactured by San-Apro Co., Ltd.) as a catalyst were charged into a 200 mL three-neck flask, and the reaction was carried out under stirring at 100 ° C. for 48 hours. After the reaction was completed, ethyl acetate was added to the reaction mixture, and the resulting solution was washed with water three times, and the organic layer was dried using magnesium sulfate, and the solvent was then distilled off to obtain 9.0 g of liquid crystal aligning polyorganosiloxane (APS-1). The weight average molecular weight Mw of the obtained polymer was 9,900.

[Synthesis Example 11: Synthesis of polyorganosiloxane (PS1)]
Into a reaction vessel equipped with a stirrer, a thermometer, a dropping funnel, and a reflux condenser, 31 g of p-styryltrimethoxysilane, 70 g of tetrahydrofuran, 33 g of triethylamine, and 25 g of deionized water were added and mixed at room temperature. Next, the mixture was reacted at 60° C. for 3 hours while stirring under reflux. After the reaction was completed, the organic layer was taken out, 60 g of diethylene glycol diethyl ether was added, and the mixture was concentrated by heating. The mixture was concentrated until the solid content concentration reached 30%, to obtain a diethylene glycol diethyl ether solution of polysiloxane (PS1).
[Synthesis Examples 12 and 13]
Diethylene glycol diethyl ether solutions of polyorganosiloxanes (PS-2) and (PS-3) were obtained in the same synthesis method as in Synthesis Example 11, except that the raw materials used were as shown in Table 1 below. The weight average molecular weights Mw of the obtained polyorganosiloxanes are also shown in Table 1 below.

In Table 1, the abbreviations of the raw material silane compounds have the following meanings:
STTMS: p-styryltrimethoxysilane ECETMS: 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane PTMS: phenyltrimethoxysilane

[Reference Example 1]
<Preparation of Liquid Crystal Alignment Agent>
Polyimide (PI-1) was used as a polymer, and trimethyl phosphate (PTM), N-methyl-2-pyrrolidone (NMP) and butyl cellosolve (BC) were added as solvents to obtain a solution with a solvent composition of PTM:NMP:BC=20:40:40 (weight ratio) and a solid content concentration of 6.5% by weight. The solution was filtered using a filter with a pore size of 1 μm to prepare a liquid crystal alignment agent (S-1). The liquid crystal alignment agent (S-1) is mainly for manufacturing a vertical alignment type liquid crystal display element.

<Evaluation of Swelling Properties of Printing Plate>
The liquid crystal alignment agent (S-1) was used to evaluate the ease of swelling (swelling characteristics) of the APR plate. The APR plate is a resin plate formed of a liquid photosensitive resin in which the ultraviolet irradiated portion is cured, and is generally used as a printing plate for liquid crystal alignment film printers. When the liquid crystal alignment agent and the APR plate are brought into contact with each other, the APR plate is less likely to swell, meaning that the liquid crystal alignment agent is less likely to penetrate into the APR plate during printing, and the printability is good. The swelling characteristics were evaluated by immersing the APR plate in the liquid crystal alignment agent for one day and measuring the weight change of the APR plate before and after immersion. At this time, when the weight increase rate (swelling rate) of the APR plate is less than 4%, the APR plate is evaluated as being less likely to swell and good (○), and when the increase rate is 4% or more, the APR plate is evaluated as being easily swelled and bad (×). As a result, in this example, the swelling rate was 3.5%, and the swelling characteristics were "good (○)". The swelling rate was calculated using the following formula (2).
Swelling ratio [%] = (W ² - W ¹ /W ¹ ) × 100 ... (2)
(In formula (2), ^W1 is the weight of the APR plate before immersion, and ^W2 is the weight of the APR plate after immersion.)

<Evaluation of Printing Properties>
The liquid crystal alignment agent (S-1) prepared above was evaluated for printability (continuous printability) when printing was performed continuously on a substrate. The evaluation was performed as follows. First, using a liquid crystal alignment film printer (manufactured by Nihon Photo Printing Co., Ltd., Angstromer type "S40L-532"), the liquid crystal alignment agent (S-1) was printed on the transparent electrode surface of a glass substrate with a transparent electrode made of an ITO film under the condition that the amount of liquid crystal alignment agent (S-1) was dropped on the anilox roll in a reciprocating manner of 20 drops (about 0.2 g). Printing on the substrate was performed 20 times at 1-minute intervals, using a new substrate.
Next, the liquid crystal alignment agent (S-1) was dispensed (one way) on the anilox roll at 1 minute intervals, and the anilox roll and the printing plate were brought into contact with each other (hereinafter, referred to as "idle run") for a total of 10 times (during this time, printing on the glass substrate was not performed). Note that this idle run was performed in order to intentionally perform printing of the liquid crystal alignment agent under harsh conditions.
After 10 idle runs, the main printing was performed using a glass substrate. In the main printing, after the idle run, five substrates were inserted at 30-second intervals, and each substrate after printing was heated (pre-baked) at 80° C. for 1 minute to remove the solvent, and then heated (post-baked) at 200° C. for 10 minutes to form a coating film with a thickness of about 80 nm. The printability (continuous printability) was evaluated by observing this coating film with a microscope at a magnification of 20 times. The evaluation was as follows: continuous printability "good (○)" when no polymer precipitation was observed from the first main printing after the idle run; continuous printability "fair (△)" when polymer precipitation was observed in the first main printing after the idle run but was not observed during five main printings; and continuous printability "poor (×)" when polymer precipitation was observed even after five main printings were repeated. As a result, in this example, the continuous printability was "good (○)". In addition, it has been found through experiments that in the case of a liquid crystal alignment agent with good printability, the precipitation of the polymer improves (disappears) while the substrate is continuously fed in. Furthermore, the number of idle runs was changed to 15, 20, and 25, and the printability of the liquid crystal alignment agent was evaluated in the same manner as above for each run. In this example, the results were "good (○)" when the idle runs were 15 and 20, and "fair (△)" when the idle runs were 25.

[Reference Examples 2 to 31 and Comparative Examples 1 to 5]
Except for changing the type and composition of the polymer and the solvent used as shown in Table 2 below, liquid crystal alignment agents (S-2) to (S-31) and (SR-1) to (SR-5) were prepared in the same manner as in Reference Example 1. In addition, the swelling characteristics and printability of the printing plate were evaluated for each liquid crystal alignment agent in the same manner as in Reference Example 1. The results are shown in Table 2 below.

In Table 2, for those (Reference Examples 18 to 31) in which two types of polymers were used as polymer components, the proportion (weight ratio) of each polymer relative to 100 parts by weight of the total amount of the polymer used is also shown. Of the liquid crystal alignment agents, (S-2) to (S-17), (SR-1) to (SR-5) are mainly for the manufacture of vertical alignment type liquid crystal display elements, (S-18) to (S-23) are mainly for the manufacture of TN type liquid crystal display elements, and (S-24) is mainly for the manufacture of IPS type liquid crystal display elements, (S-29) to (S-31) are mainly for the manufacture of vertical alignment type liquid crystal display elements by the photoalignment method, and (S-25) to (S-28) are mainly for the manufacture of PSA type liquid crystal display elements. In Table 2, the numerical values of the solvent composition indicate the blending proportion (weight ratio) of each compound with respect to the total amount of the solvent used in the preparation of the liquid crystal alignment agent (the same applies to Tables 3 to 5 below). The symbols of the solvent composition have the following meanings.
a: Trimethyl phosphate b: Triethyl phosphate c: Hexamethylphosphoric triamide d: N-methyl-2-pyrrolidone e: N-ethyl-2-pyrrolidone f: γ-butyrolactone g: γ-valerolactone h: δ-valerolactone i: N,N-diethylacetamide j: Butyl cellosolve k: Diethylene glycol diethyl ether l: Propylene glycol monomethyl ether acetate

[Reference Examples 32 to 52]
Except for changing the type and composition of the polymer and the solvent used as shown in Table 3, liquid crystal alignment agents (S-32) to (S-52) were prepared in the same manner as in Reference Example 1. In addition, the swelling characteristics and printability of the printing plate were evaluated for each liquid crystal alignment agent in the same manner as in Reference Example 1. The results are shown in Table 3.

In Table 3, for those in which two types of polymers were used as the polymer component (Reference Examples 40 to 43, 50 to 52), the proportion (weight ratio) of each polymer used relative to 100 parts by weight of the total amount of the polymers used is also shown. In addition, among the liquid crystal alignment agents, (S-32) to (S-39) and (S-44) to (S-49) are mainly for manufacturing vertical alignment type liquid crystal display elements, and (S-40) to (S-43) and (S-50) to (S-52) are mainly for manufacturing TN type liquid crystal display elements. In Table 3, the symbols of the solvent composition have the following meanings. d and j are the same as those in Table 2 above.
m: N,N'-dimethylpropylene urea n: 4-formylmorpholine o: 3-methyl-2-oxazolidone p: tetrahydro-4H-pyran-4-one r: tetramethylene sulfoxide s: 3-methylcyclohexanone t: 4-methylcyclohexanone

[Examples 53 to 55, Reference Example 56]
Except for changing the polymer components and the type and composition of the solvent used as shown in Table 4 below, liquid crystal alignment agents (S-53) to (S-56) were prepared in the same manner as in Reference Example 1. In addition, the swelling characteristics and printability of the printing plate were evaluated for each liquid crystal alignment agent in the same manner as in Reference Example 1. The results are shown in Table 4 below.

In Table 4, for those in which two types of polymers were used as polymer components (Example 55, Reference Example 56), the proportion (weight ratio) of each polymer used relative to 100 parts by weight of the total amount of polymers used is also shown. Among the liquid crystal alignment agents, (S-53) and (S-54) are primarily for the manufacture of vertical alignment type liquid crystal display elements, while (S-55) and (S-56) are primarily for the manufacture of TN type liquid crystal display elements. In Table 4, the symbols for the solvent compositions have the following meanings. d and j are the same as those in Table 2 above.
q: 5-methyl-2-furaldehyde u: N,N-dimethyl lactamide (compound represented by the following formula (10-1))

[Reference Examples 57 to 60]
Liquid crystal alignment agents (S-57) to (S-60) were prepared in the same manner as in Reference Example 1 above, except that the polymers used and the types and compositions of the solvents were changed as shown in Table 5 below. In addition, for each liquid crystal alignment agent, the swelling characteristics and printability of the printing plate were evaluated in the same manner as in Reference Example 1 above. The results are shown in Table 5 below. In Table 5, the numerical values in the column for polymer component indicate the proportion (weight ratio) of each polymer used relative to 100 parts by weight of the total amount of the polymers used. The symbols (d, m, j) for the solvent compositions are the same as in Tables 2 and 3 above.

The above results show that the liquid crystal alignment agents containing the above-mentioned specific solvents (Reference Examples 1 to 52, 56 to 60 and Examples 53 to 55) are less likely to cause the printing plate to swell and have good continuous printability. In contrast, the comparative examples not containing the above-mentioned specific solvents were inferior to the Examples and Reference Examples in either swelling properties or continuous printability.

Claims (3)

Contains a polymer component and a specific solvent,
The specific solvent is a liquid crystal aligning agent which is a compound represented by the following formula (3).

(In formula (3), R ⁷ to R ¹⁰ are each independently a hydrogen atom or a monovalent organic group. However, one of R ⁷ and R ¹⁰ is —COR ^b . R ^b is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. ) The liquid crystal alignment agent according to claim 1, wherein the polymer component contains at least one polymer selected from the group consisting of polyamic acid, polyamic acid ester, polyimide, and polyorganosiloxane. The liquid crystal alignment agent according to claim 1 or 2, wherein the content of the specific solvent is 1 to 80% by weight based on the total amount of the solvent in the liquid crystal alignment agent.