KR102000322B1 - Method for preparing polyimide varnish, and liquid crystal aligning agent - Google Patents

Abstract

A method for preparing a polyimide varnish which dissolves and contains polyimide to inhibit the generation of agglomerates to obtain a polyimide varnish having excellent printing properties, and a liquid crystal aligning agent using the obtained polyimide varnish.
A polyimide varnish prepared by imidizing each of the polyimide precursors in a solution containing two or more kinds of polyimide precursors and containing two or more kinds of polyimides dissolved therein is prepared or a polyimide precursor is prepared by mixing two or more kinds of polyimides in a powder state And the obtained polyimide powder mixed with two or more types of polyimides is dissolved in a solvent to prepare a polyimide varnish.

Description

METHOD FOR PREPARING POLYIMIDE VARNISH, AND LIQUID CRYSTAL ALIGNING AGENT [0001] The present invention relates to a method for preparing a polyimide varnish,

The present invention relates to a method for preparing a polyimide varnish and a liquid crystal aligning agent using the obtained polyimide varnish.

A film made of an organic material such as a polymer material is widely used as an interlayer insulating film or a protective film in an electronic device due to its ease of formation and insulation performance. As an organic material widely used in such an electronic device, polyimide is known.

For example, in a liquid crystal display element well known as a display device, a polyimide film is used as a liquid crystal alignment film. A liquid crystal display element has a structure in which liquid crystal molecules are sandwiched by a liquid crystal alignment film formed on each surface of a pair of substrates. A liquid crystal molecule aligned in a predetermined direction along the pretilt angle by the liquid crystal alignment film responds by a voltage applied to an electrode formed between the substrate and the liquid crystal alignment film.

This liquid crystal alignment film is generally produced by applying a so-called " rubbing treatment ", in which a surface of a polyimide film formed on a substrate on which an electrode is formed is rubbed by applying pressure to the surface thereof with rayon or nylon cloth.

A liquid crystal alignment film for VA (Vertical Alignment) in which no rubbing treatment is performed and a photo alignment film for orienting the liquid crystal by applying anisotropy to the film surface by irradiating with polarized UV are also attracting attention.

As a method of forming a polyimide film to be a liquid crystal alignment film on a substrate having an electrode formed thereon, a liquid crystal aligning agent containing a polyimide precursor such as polyamic acid (also referred to as polyamide acid) and prepared varnish is used, And then imidizing it on a substrate is known.

As another method, there is a method of dissolving polyimide that has been imidized in advance in a solvent to prepare a so-called solvent-soluble polyimide varnish, and forming a polyimide film by using the liquid crystal aligning agent using the polyimide varnish.

Among them, the method using a liquid crystal aligning agent using a solvent-soluble polyimide varnish has a feature that a polyimide film having good characteristics when used as a liquid crystal alignment film can be formed even at a relatively low temperature. However, the polyimide is inferior in solubility to an organic solvent in general as compared with polyamic acid or the like, and therefore, when imidation is carried out in advance, the printability on the substrate is lowered, which makes it difficult to form a uniform coating film have. In addition, there has been a case where insolubilization is made with respect to the conventional solvent used for the varnish and the polyimide can not be contained in the liquid crystal aligning agent.

As a method for solving such a problem, there has been proposed a method (for example, see Patent Document 1) of obtaining a liquid crystal aligning agent by blending a polyimide precursor into a varnish prepared by dissolving polyimide in a solvent.

Further, a method of obtaining a liquid crystal aligning agent by blending polyimide having different imidization rates (for example, see Patent Document 2 and Patent Document 3) has been proposed. These liquid crystal aligning agents form a polyimide film using phase separation to obtain a liquid crystal alignment film. However, the conventional liquid crystal aligning agent using phase separation tends to cause a problem that when the liquid crystal aligning agent is printed on a substrate for forming a coating film, it is whitened by moisture absorption to precipitate the aggregate. In addition, the phase separation property changes depending on the firing conditions after the application to the substrate, and the characteristics of the alignment film such as the formation tilt angle required for the liquid crystal alignment film and the voltage holding ratio (also referred to as VHR) There was also a problem.

As for the change of the characteristics of the alignment film, a method of preparing a varnish by using polyimide having a high imidization ratio and preparing the liquid crystal aligning agent by using the varnish is effective. As such a liquid crystal aligning agent, a liquid crystal aligning agent blended with a soluble polyimide using a specific diamine has been proposed (see, for example, Patent Document 4).

However, also in such a liquid crystal aligning agent, when the liquid crystal aligning agent is dried at the time of printing for forming a coating film on the substrate, there is a case that the aggregated matter is generated in a short time.

Further, in a liquid crystal display device using a liquid crystal alignment film, there is a case where gap unevenness occurs between the substrates holding the liquid crystal molecules.

Further, a liquid crystal alignment system containing a soluble polyimide using a high boiling point polar solvent has been proposed in order to solve the problems of printing and agglomeration as described above (see, for example, Patent Document 5). However, it is not said that the effect of the improvement is sufficient for the aggregates generated upon coating and drying on the substrate.

Japanese Patent Application Laid-Open No. 08-220541 Japanese Patent Application Laid-Open No. 09-297312 Japanese Laid-Open Patent Publication No. 09-311338 International Publication No. 2008/62877 pamphlet International Publication No. 2009/148100 pamphlet

As described above, there is a demand for a technique for providing a polyimide varnish which can suppress the occurrence of aggregates due to moisture absorption and is excellent in printability. A liquid crystal aligning agent which is prepared from a polyimide varnish and suppresses the generation of agglomerates, has excellent printing properties and is capable of forming a liquid crystal alignment film.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for preparing polyimide varnish which suppresses occurrence of agglomerates and is excellent in printing property.

It is also an object of the present invention to provide a liquid crystal aligning agent having excellent printability in which the occurrence of aggregates is suppressed by using the polyimide varnish obtained by the above preparation method.

The present invention has the following points.

(1) A process for preparing a polyimide varnish comprising imidizing each of the polyimide precursors in a solution containing two or more polyimide precursors and dissolving two or more polyimides.

(2) The method for preparing a polyimide varnish as described in (1) above, wherein the concentration of the polyimide precursor in the solution is 1 to 12 mass%.

(3) Imidization of the polyimide precursor in the solution is carried out after the solution containing the two or more kinds of polyimide precursors is prepared for 10 minutes to 12 hours after the completion of the step (1) or (2) ≪ / RTI >

(4) at least one of the two or more kinds of polyimide precursors is 1,2,3,4-cyclobutane tetracarboxylic acid dianhydride, 3,4-dicarboxy-1,2,3,4-tetrahydro (1) to (3), wherein the polyimide precursor is a polyimide precursor formed using at least one selected from the group consisting of an aromatic tetracarboxylic acid dianhydride and an aromatic tetracarboxylic acid dianhydride containing an aromatic ring, ≪ / RTI >

(5) A process for preparing a polyimide varnish comprising mixing two or more kinds of polyimides in powder form, dissolving the resulting polyimide powder in a solvent, and dissolving at least two kinds of polyimides.

(6) at least one of the two or more kinds of polyimides is at least one selected from 1,2,3,4-cyclobutane tetracarboxylic acid dianhydride, 3,4-dicarboxy-1,2,3,4-tetrahydro- (5), wherein the polyimide precursor is a polyimide obtained by imidizing a polyimide precursor formed by using at least one selected from the group consisting of 1-naphthalene succinic dianhydride and aromatic tetracarboxylic acid dianhydride containing an aromatic ring Preparation method of varnish.

(7) The process for producing a polyimide varnish as described in any one of (1) to (6) above, wherein the polyimide has a weight average molecular weight of 10,000 to 15,000.

(8) A polyimide varnish obtained by using the method for preparing a polyimide varnish according to any one of (1) to (4) above.

(9) A polyimide varnish obtained by using the process for preparing a polyimide varnish according to any one of (5) to (7).

(10) A liquid crystal aligning agent obtained by using the polyimide varnish according to (8) or (9).

(11) The liquid crystal aligning agent according to (10), further comprising at least one selected from the group consisting of N-methyl-2-pyrrolidone and? -Butyrolactone.

(12) A liquid crystal alignment film obtained from the liquid crystal aligning agent according to any one of (10) and (11).

(13) The liquid crystal alignment film according to (12), wherein the film thickness is 10 to 200 占 퐉.

(14) A liquid crystal display element comprising the liquid crystal alignment film according to (12) or (13).

According to the method for preparing a polyimide varnish of the present invention, it is possible to obtain a polyimide varnish which dissolves and contains polyimide, suppresses the generation of aggregates, has excellent printability and is easy to form a uniform coating film.

Further, by using the polyimide varnish obtained by the present invention, it is possible to provide a liquid crystal aligning agent containing polyimide, suppressing the generation of agglomerates, having excellent printability and being easy to form a uniform coating film.

The present inventors have conducted intensive studies and, as a result, have obtained the following findings and have completed the present invention.

That is, as disclosed in Patent Documents 2 and 3, conventionally, a liquid crystal aligning agent containing two or more polyimides is known, but a conventional polyimide varnish containing two or more types of polyimides is not limited to two or more types A solution containing a polyimide precursor is separately prepared, imidization is separately carried out in each solution, and then recovery of the polyimide and purification of the polyimide are performed for each of the obtained polyimide solutions do. Then, each of the obtained polyimides is dissolved in a solvent to obtain two or more kinds of polyimide solutions corresponding to the number of kinds of polyimide. Then, each polyimide solution is mixed to prepare a polyimide varnish containing two or more polyimides. In the polyimide varnish thus obtained, aggregates are generated in a comparatively short time, as shown in the comparative examples described later. Therefore, also in the case of the liquid crystal aligning agent using such a polyimide varnish, similarly, Thereby generating an aggregate.

DISCLOSURE OF THE INVENTION The present inventors have conducted intensive research to solve the above-mentioned difficulties of a conventional polyimide varnish containing two or more kinds of polyimides. As a result, it has been found that, in a solution containing two or more kinds of polyimide precursors, A polyimide varnish prepared by dissolving two or more kinds of polyimides respectively, or a method of mixing two or more types of polyimides in a powder state, and mixing the obtained polyimide powder with two or more types of polyimides The above problems can be solved by a method of dissolving them simultaneously in a solvent and preparing them.

It is not always clear why this problem can be solved by the method of preparing such a polyimide varnish, but it is considered as follows. That is, in the method of simultaneously imidizing two kinds of polyimide precursors in a solution containing two or more kinds of polyimide precursors, in the solution containing two or more kinds of polyimide precursors, the contained polyimide precursors interact with each other , Amide exchange with a part of the polyimide precursor occurs, and the compatibility is improved. As a result, the obtained polyimide varnish is considered to be excellent in printability and to inhibit the formation of aggregates.

The same applies to the method of mixing two or more kinds of polyimides in a powder state and simultaneously dissolving the obtained polyimide powder mixed with two or more types of polyimide in a solvent, and among the two or more kinds of polyimides, There is an unconverted polyimide precursor defined by the polyimide precursor. However, it is considered that such polyimide precursors interact with each other to cause amide exchange with a part of the polyimide precursor, thereby improving compatibility.

[Polyimide varnish and its preparation method]

In the present invention, the term " two or more kinds of polyimides " means that the structures of the polyimide precursors as the corresponding raw materials are different, respectively. That is, even if the tetracarboxylic acid dianhydride and the diamine, which are the raw materials of the polyimide precursor, are different from each other, or the combination of the same tetracarboxylic acid dianhydride and diamine is used, Lt; / RTI > precursor.

In the present invention, the polyimide precursor is a polyamic acid and / or a polyamic acid ester. In the present invention, a particularly preferable polyimide precursor is polyamic acid.

In the present invention, two or more kinds of polyimides or two or more kinds of polyimide precursors are usually two kinds, but in some cases, they may be three kinds or more, or four or more kinds.

In the method for preparing a polyimide varnish of the present invention, a solution containing two or more kinds of polyimide precursors corresponding to each of two or more types of polyimide to be contained is first prepared. Each of the polyimide precursors contained in the solution is formed from different combinations of tetracarboxylic acid dianhydrides or derivatives thereof and diamines and has a different structure from each other.

This solution is used as a reaction solution, and imidization of each polyimide precursor contained therein is carried out. As a result, a polyimide solution containing two or more polyimides is obtained. This polyimide solution can be used directly as the polyimide varnish of the present invention. Preferably, the polyimide is recovered from the obtained polyimide solution and the polyimide is purified, and then the polyimide varnish of the present invention is prepared by dissolving at least two kinds of polyimide in a solvent .

In the method for preparing a polyimide varnish of the present invention, imidization and subsequent recovery and purification can be performed only once, even if the polyimide varnish contains two or more kinds of polyimides. On the other hand, in the above-mentioned conventional method, it is necessary to imidize each solution containing two or more kinds of polyimide precursors, and thereafter carry out recovery and purification. Therefore, the production method of the polyimide varnish of the present invention can improve the production efficiency and reduce the amount of the solvent and catalyst required for the imidation, as compared with the conventional method. The process for preparing a polyimide varnish of the present invention has a great advantage in terms of production as compared with the conventional process.

The tetracarboxylic acid dianhydride or derivative thereof and the diamine to be used as raw materials in forming the polyimide precursor by polyimide are appropriately selected according to the polyimide varnish containing two or more polyimides to be produced .

As a method of preparing a solution containing two or more kinds of polyimide precursors, a solution containing a polyimide precursor corresponding to each of two or more kinds of polyimides contained in the polyimide varnish is prepared separately, Can be mixed.

In addition, a solution containing a polyimide precursor corresponding to at least one of two or more polyimides contained in the polyimide varnish is prepared, and an isolated polyimide precursor corresponding to another polyimide is added to the solution to dissolve , It is also possible to prepare a solution containing two or more kinds of polyimide precursors.

An example of a method for preparing the polyimide varnish of the present invention will be described in more detail below.

In the method for preparing the polyimide varnish of the present invention, first, a tetracarboxylic acid dianhydride or a derivative thereof having a desired structure is selected, and corresponding diamines having a desired structure are selected. Then, they are reacted with each other in a suitable solvent and polymerized to obtain a polyimide precursor such as polyamic acid having a desired structure in a solution state. In the same manner, a plurality of kinds of solutions each containing a polyimide precursor having a different structure are obtained.

It is also possible to obtain a polyimide precursor in a solution state, recover the polyimide precursor in a solution, perform necessary purification and the like, and then use the recovered polyimide precursor in the preparation of the polyimide varnish. For example, the polyimide precursor may be dissolved again in a desired solvent, and a solution of the obtained polyimide precursor may be used in the preparation of the polyimide varnish.

In obtaining a polyimide precursor such as polyamic acid, it is preferable to use a tetracarboxylic acid dianhydride as the tetracarboxylic acid dianhydride or a derivative thereof having a desired structure.

In the process for preparing the polyimide varnish of the present invention, tetracarboxylic acid dianhydrides and diamines that can be selected are described in detail below.

≪ Tetracarboxylic acid dianhydride and derivatives thereof >

The tetracarboxylic acid dianhydride to be reacted with the diamine is not particularly limited in order to obtain the polyamic acid used in the process for preparing the polyimide varnish of the present invention. Specific examples thereof are given below.

Examples of the tetracarboxylic acid dianhydride having an alicyclic or aliphatic structure include 1,2,3,4-cyclobutane tetracarboxylic acid dianhydride, 1,2-dimethyl-1,2,3,4-cyclobutane tetra Carboxylic acid dianhydride, 1,3-dimethyl-1,2,3,4-cyclobutane tetracarboxylic acid dianhydride, 1,2,3,4-tetramethyl-1,2,3,4-cyclobutane Tetracarboxylic acid dianhydride, 1,2,3,4-cyclopentanetetracarboxylic acid dianhydride, 2,3,4,5-tetrahydrofuran tetracarboxylic acid dianhydride, 1,2,4,5- Cyclohexanetetracarboxylic acid dianhydride, 3,4-dicarboxy-1-cyclohexylsuccinic dianhydride, 3,4-dicarboxy-1,2,3,4-tetrahydro-1-naphthalenesuccinic dianhydride, 1 , 2,3,4-butanetetracarboxylic acid dianhydride, bicyclo [3,3,0] octane-2,4,6,8-tetracarboxylic acid dianhydride, 3,3 ', 4,4' - dicyclohexyltetracarboxylic acid dianhydride, 2,3,5-tricarboxycyclopentyl acetic acid dianhydride, 3,7-dibutyl-1,5-diene-cyclooctadiene -1,2,5,6-tetracarboxylic acid dianhydride, tricyclo [4.2.1.0 ^2,5] nonane -3,4,7,8 - tetracarboxylic acid -3,4: 7,8-2 anhydride, hexahydro cyclo ^{[6.6.0.1 2,7 .0 3,6 .1 9,14 .0} 10,13] hexadecane -4,5,11 , 12-tetracarboxylic acid-4,5: 11,12-2 anhydride, 4- (2,5-dioxotetrahydrofuran-3-yl) -1,2,3,4-tetrahydronaphthalene- , 2-dicarboxylic acid anhydride, and the like.

An aromatic tetracarboxylic acid dianhydride may be used. The aromatic tetracarboxylic acid dianhydride is a tetracarboxylic acid dianhydride containing an aromatic ring.

The aromatic tetracarboxylic acid dianhydride may be used in addition to the tetracarboxylic dianhydride having an alicyclic structure or an alicyclic structure. When the aromatic tetracarboxylic acid dianhydride is used as such, the liquid crystal alignment film formed from the liquid crystal aligning agent using the obtained polyimide varnish can improve the liquid crystal alignability and reduce the accumulated charge of the liquid crystal display element.

Examples of usable aromatic tetracarboxylic acid dianhydrides include pyromellitic dianhydride, 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, 2,2', 3,3'-biphenyltetracar 3,3 ', 4,4'-benzophenonetetracarboxylic acid dianhydride, 2,3,3', 4'-biphenyltetracarboxylic acid dianhydride, 3,3 ' (3,4-dicarboxyphenyl) ether dianhydride, bis (3,4-dicarboxyphenyl) sulfone dianhydride, 1,2,5,6-naphthalene tetracarboxylic dianhydride, Carboxylic acid dianhydride, and 2,3,6,7-naphthalenetetracarboxylic acid dianhydride.

Among them, the tetracarboxylic acid dianhydride may be 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride (CBDA), 3,4-dicarboxy-1,2,3,4-tetrahydro-1 (TDA), pyromellitic dianhydride (PMDA), 2,3,5-tricarboxycyclopentyl acetic acid dianhydride (TCA) and the like are preferably used. The polyamic acid obtained by using them is particularly preferable in the realization of polyimide varnish which is excellent in printing property and is inhibited from forming aggregates at the time of forming a coating film on a substrate. These tetracarboxylic acid dianhydrides are considered to be preferable for the interaction of the above-described polyimide precursors, in particular, for the amide exchange, and it is interpreted as exerting an effect of improving the printing property and the like.

The tetracarboxylic acid dianhydride is preferably used in consideration of the printing property of the obtained polyimide varnish and the effect of suppressing the formation of coagulated material at the time of forming a coating film and also the liquid crystal orientation of the liquid crystal alignment film formed from the liquid crystal aligning agent using the obtained polyimide varnish One or two or more of them may be used in combination in order to form one polyimide precursor, depending on the characteristics such as chargeability, voltage holding property, and accumulated charge.

When two or more kinds of tetracarboxylic acid dianhydrides are used in combination to form one kind of polyimide precursor, the above-mentioned 1,2,3,4-cyclobutane tetracarboxylic acid dianhydride (CBDA), 3, (TDA), pyromellitic dianhydride (PMDA), 2,3,5-tricarboxycyclopentyl acetic acid dianhydride (TCA ) Is preferably at least 10 mol% based on the total amount of the tetracarboxylic acid dianhydride. More preferably, it is at least 30 mol% of the entire tetracarboxylic acid dianhydride. In particular, 60 to 100 mol% is particularly preferable.

In the method for preparing a polyimide varnish of the present invention, a tetracarboxylic acid dialkyl ester which is a derivative of a tetracarboxylic acid dianhydride can be used to obtain a polyamic acid ester as a polyimide precursor. The tetracarboxylic acid dialkyl ester which can be used is not particularly limited. Specific examples thereof are given below.

Specific examples of the aliphatic tetracarboxylic acid diester include 1,2,3,4-cyclobutane tetracarboxylic acid dialkyl ester, 1,2-dimethyl-1,2,3,4-cyclobutane tetracarboxylic acid dialkyl ester, 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic acid dialkyl ester, 1,2,3,4-tetramethyl-1,2,3,4-cyclobutanetetracarboxylic acid dialkyl ester , 1,2,3,4-cyclopentanetetracarboxylic acid dialkyl ester, 2,3,4,5-tetrahydrofuran tetracarboxylic acid dialkyl ester, 1,2,4,5-cyclohexanetetracarboxylic acid di Alkyl esters, 3,4-dicarboxy-1-cyclohexylsuccinic acid dialkyl ester, 3,4-dicarboxy-1,2,3,4-tetrahydro-1-naphthalenesuccinic acid dialkyl ester, 1,2,3 , 4-butanetetracarboxylic acid dialkyl ester, bicyclo [3,3,0] octane-2,4,6,8-tetracarboxylic acid dialkyl ester, 3,3 ', 4,4'-dicyclohexyl Tetracarboxylic acid di Alkyl esters, 2,3,5-tricarboxycyclopentyl acetic acid dialkyl ester, cis-3,7-dibutylcycloocta-1,5-diene-1,2,5,6-tetracarboxylic acid dialkyl ester, tricyclo [4.2.1.0 ^2,5] nonane -3,4,7,8- tetracarboxylic acid -3,4: 7,8-di-alkyl ester, cyclo hexa [6.6.0.1 ^2,7 .0 ^{3, 6} .1 ^9,14 .0 ^10,13] hexadecane -4,5,11,12- tetracarboxylic acid 4,5: 11,12- di-alkyl ester, 4- (2,5-dioxotetrahydro Hydrofuran-3-yl) -1,2,3,4-tetrahydronaphthalene-1,2-dicarbonyl alkyl ester.

Examples of the aromatic tetracarboxylic acid dialkyl ester include pyromellitic acid dialkyl ester, 3,3 ', 4,4'-biphenyltetracarboxylic acid dialkyl ester, 2,2', 3,3'-biphenyltetracarboxyl Biphenyltetracarboxylic acid dialkyl ester, 3,3 ', 4,4'-benzophenonetetracarboxylic acid dialkyl ester, 2,3,3', 4 Bis (3,4-dicarboxyphenyl) ether dialkyl ester, bis (3,4-dicarboxyphenyl) sulfonyl alkyl ester, 1,2,5,6-naphthalene Tetracarboxylic acid dialkyl ester, and 2,3,6,7-naphthalenetetracarboxylic acid dialkyl ester.

<Diamine>

The diamine usable for the reaction with the tetracarboxylic acid dianhydride or the like in obtaining the polyimide precursor to be used in the process for preparing the polyimide varnish of the present invention is not particularly limited. It is preferable that selection is made to correspond to the structure of the desired polyimide precursor. Specific examples of selectable diamines are as follows.

Examples of the alicyclic diamine include 1,4-diaminocyclohexane, 1,3-diaminocyclohexane, 4,4'-diaminodicyclohexylmethane, 4,4'-diamino-3,3'-dimethyl Dicyclohexylamine, isophoronediamine, and the like.

Examples of the aromatic diamines include aromatic diamines such as o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, 2,4-diaminotoluene, 2,5-diaminotoluene, Diamino-2-methoxybenzene, 2,5-diamino-p-xylene, 1,3-diamino-4-chlorobenzene, 3,5-diaminobenzoic acid, , 5-dichlorobenzene, 4,4'-diamino-1,2-diphenylethane, 4,4'-diamino-2,2'-dimethylbibenzyl, 4,4'-diaminodiphenylmethane, 3,3'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 4,4'-diamino-3,3'-dimethyldiphenylmethane, 2,2'-diaminostilbene, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfide, 4,4'-diamine Diaminodiphenylsulfone, 4,4'-diaminobenzophenone, 1,3-bis (3-aminophenoxy) benzene, 1,3-bis Benzene, 1,4-bis (4-aminophenoxy) benzene, 3,5-bis Bis (4-aminophenoxy) methyl] propane, 2,2-bis [4- (4-aminophenoxy) benzene, Bis [4- (4-aminophenoxy) phenyl] propane, bis [4- Bis (4-aminophenyl) phenyl] sulfone, 1,1-bis (4-aminophenyl) cyclohexane, 4-aminophenyl) fluorene, 2,2-bis (3-aminophenyl) hexafluoropropane, 2,2- , 2,4-diaminodiphenylamine, 1,8-diaminonaphthalene, 1,5-diaminonaphthalene, 1,5-diaminoanthraquinone, 1,3-diaminopyrrene, 1,6-diamino Pyrene, 1,8-diaminopyrene, 2,7-diaminofluorene, 1,3-bis (4-aminophenyl) tetramethyldisiloxane, benzidine, 2,2'-dimethylbenzidine, (4-aminophenyl) ethane, 1 Bis (4-aminophenyl) pentane, 1,6-bis (4-aminophenyl) Bis (4-aminophenyl) heptane, 1,8-bis (4-aminophenyl) octane, 1,9- ) Decane, 1,3-bis (4-aminophenoxy) propane, 1,4-bis (4-aminophenoxy) butane, 1,5- (4-aminophenoxy) hexane, 1,7-bis (4-aminophenoxy) heptane, 1,8- Di (4-aminophenyl) butane-1,4-dioate, di (4-aminophenoxy) decane, di Di (4-aminophenyl) heptane-1, 7-dioate, di (4-aminophenyl) Di (4-aminophenyl) nonane-1,9-dioate, di (4-aminophenyl) Bis [4- (4-aminophenoxy) phenoxy] propane, 1,4-bis [4- Bis [4- (4-aminophenoxy) phenoxy] pentane, 1,6-bis [4- Phenoxy] phenoxy] heptane, 1,8-bis [4- (4-aminophenoxy) phenoxy] octane, 1,9- , 10-bis [4- (4-aminophenoxy) phenoxy] decane, and the like.

Examples of the aromatic-aliphatic diamine include diamines represented by the following formula [DAM].

[Chemical Formula 1]

(In the formula [DAM], Ar represents a benzene ring or a naphthalene ring, R ₁ represents an alkylene group having 1 to 5 carbon atoms, R ₂ Is a hydrogen atom or a methyl group.

Specific examples of the aromatic-aliphatic diamines include 3-aminobenzylamine, 4-aminobenzylamine, 3-amino-N-methylbenzylamine, Amino-N-methylphenethylamine, 3- (3-aminopropyl) aniline, 4- (3-aminopropyl) aniline, 3- 4- (4-aminobutyl) aniline, 3- (4-methylaminobutyl) aniline, 4- 3- (5-methylaminopentyl) aniline, 4- (5-methylaminopentyl) aniline, Aniline, 2- (6-aminonaphthyl) methylamine, 3- (6-aminonaphthyl) methylamine, 2- .

Examples of the heterocyclic diamine include 2,6-diaminopyridine, 2,4-diaminopyridine, 2,4-diamino-1,3,5-triazine, 2,7-diaminodibenzofuran, 3 Diaminocarbazole, 2,4-diamino-6-isopropyl-1,3,5-triazine, 2,5-bis (4-aminophenyl) -1,3,4-oxadiazole And the like.

Examples of the aliphatic diamine include 1,2-diaminoethane, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, Diaminoethane, 1,8-diaminooctane, 1,9-diaminononane, 1,10-diaminodecane, 1,3-diamino-2,2-dimethylpropane, 1,6-diamino- Diamino-2,5-dimethylheptane, 1,7-diamino-4,4-dimethylheptane, 1,7-diamino-3-methylheptane, 1,9- Diamino-5-methyl nonane, 1,12-diaminododecane, 1,18-diaminooctadecane, 1,2-bis (3-aminopropoxy) ethane and the like.

In order to obtain a polyimide precursor such as polyamic acid, a diamine compound having an alkyl group, a fluorine-containing alkyl group, an aromatic ring, an aliphatic ring, a heterocyclic ring, You can. Specifically, diamines represented by the following formulas [DA-1] to [DA-40] can be exemplified.

(2)

(Of the formulas [DA-1] to [DA-5], R ₆ Is an alkyl group or a fluorine-containing alkyl group having 1 to 22 carbon atoms.)

(3)

(Of the formulas [DA-6] to [DA-9], S ₅ Is, -COO-, -OCO-, -CONH-, -NHCO- , -CH 2 -, -O-, and -CO-, or NH-, R ₆ Is an alkyl group or a fluorine-containing alkyl group having 1 to 22 carbon atoms.)

[Chemical Formula 4]

(Of the formulas [DA-10] and [DA-11], S ₆ Is -O-, -OCH ₂ -, -CH ₂ O-, -COOCH ₂ -, or CH ₂ OCO- and R ₇ Is an alkyl group, an alkoxy group, a fluorine-containing alkyl group or a fluorine-containing alkoxy group having 1 to 22 carbon atoms.

[Chemical Formula 5]

(Of the formulas [DA-12] to [DA-14], S ₇ Is, -COO-, -OCO-, -CONH-, -NHCO- , -COOCH 2 -, -CH 2 OCO-, -CH 2 O-, -OCH 2 -, or CH ₂ -, and, R ₈ Is an alkyl group, an alkoxy group, a fluorine-containing alkyl group or a fluorine-containing alkoxy group having 1 to 22 carbon atoms.

[Chemical Formula 6]

(Of the formulas [DA-15] and [DA-16], S ₈ -CO-, -OCO-, -CONH-, -NHCO-, -COOCH ₂ -, -CH ₂ OCO-, -CH ₂ O-, -OCH ₂ -, -CH ₂ -, -O- or NH-, R &lt; ₉ &gt; Is a fluorine group, a cyano group, a trifluoromethyl group, a nitro group, an azo group, a formyl group, an acetyl group, an acetoxy group, or a hydroxyl group.

(7)

[Chemical Formula 8]

(Of the formulas [DA-17] to [DA-20], R ₁₀ Is an alkyl group having 3 to 12 carbon atoms, and the cis-trans isomer of 1,4-cyclohexylene is a trans-isomer).

[Chemical Formula 9]

[Chemical formula 10]

(11)

Further, in obtaining a polyimide precursor such as polyamic acid, the following diamines may be used in combination with the selectable diamine.

[Chemical Formula 12]

(In the formula [DA-35], m is an integer of 0 to 3. In the formula [DA-38], n is an integer of 1 to 5).

[DA-31] and [DA-32] use a liquid crystal alignment film formed from the polyimide varnish obtained by the process for preparing a polyimide varnish of the present invention, The voltage holding ratio (VHR) of the liquid crystal display element can be improved.

The use of the diamines [DA-33] to [DA-38] is preferable because it is effective in reducing the accumulated charge of the obtained liquid crystal display element. Use of [DA-39] or [DA-40] is also preferable because it is effective in reducing the accumulated charge of the liquid crystal display element.

In addition, in obtaining a polyimide precursor such as polyamic acid, a diaminosiloxane and the like represented by the following formula [DA-41] can be exemplified as selectable diamines.

[Chemical Formula 13]

(In the formula [DA-41], m is an integer of 1 to 10.)

Further, in obtaining the polyimide precursor, the diamine is preferably used in the form of a single polyimide precursor in accordance with the properties of the liquid crystal alignment film formed from the liquid crystal aligning agent obtained by using the polyimide varnish, such as liquid crystal aligning property, voltage holding property, , It is possible to use one kind or a mixture of two or more kinds.

Next, in the method for preparing a polyimide varnish of the present invention, a known synthetic method may be used to obtain a polyimide precursor by reaction of a tetracarboxylic acid dianhydride with a diamine. For example, it is possible to use a method of reacting a tetracarboxylic acid dianhydride and a diamine in an organic solvent. This method is preferred because the reaction progresses relatively efficiently in an organic solvent and the generation of by-products is small.

The organic solvent used for the reaction of the tetracarboxylic acid dianhydride and the diamine is not particularly limited as long as the resulting polyamic acid can be dissolved. Specific examples include N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methylcaprolactam, dimethylsulfoxide, tetramethylurea, pyridine, dimethylsulfone, Propyl alcohol, isopropyl alcohol, methoxymethyl pentanol, dipentene, ethyl amyl ketone, methyl nonyl ketone, methyl ethyl ketone, methyl isobutyl ketone, methyl isopropyl ketone, methyl cellosolve, Ethyl cellosolve acetate, ethyl cellosolve acetate, butyl carbitol, ethyl carbitol, ethylene glycol, ethylene glycol monoacetate, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, propylene glycol, propylene glycol Glycol monoacetate, propylene glycol monomethyl ether, propylene glycol-tert-butyl ether, dipropylene glycol monomethyl ether, diethylene glycol, diethylene glycol monoacetate Diethylene glycol dimethyl ether, dipropylene glycol monoacetate monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monoacetate monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol Monoacetate monopropyl ether, 3-methyl-3-methoxybutyl acetate, tripropylene glycol methyl ether, 3-methyl-3-methoxybutanol, diisopropyl ether, ethyl isobutyl ether, diisobutylene, N-hexane, n-pentane, n-octane, diethyl ether, cyclohexanone, ethylene carbonate, isopropanol, n-butanol, isobutanol, Propylene carbonate, methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, n-butyl acetate, acetic acid pro Methoxypropionic acid, 3-methoxypropionic acid, 3-methoxypropionic acid, 3-methoxypropionic acid, 3-methoxypropionic acid, 3-methoxypropionic acid, Propyl propionate, butyl 3-methoxypropionate, diglyme or 4-hydroxy-4-methyl-2-pentanone. These may be used alone or in combination. The polyimide precursor such as polyamic acid or the like may be mixed with the solvent as long as the solvent does not dissolve the polyimide precursor and does not precipitate the resulting polyimide precursor.

Further, water in the organic solvent inhibits the polymerization reaction and causes hydrolysis of the resulting polyimide precursor. Therefore, it is preferable to use an organic solvent that is dehydrated and dried.

When the tetracarboxylic acid dianhydride and the diamine are reacted in the organic solvent, the solution in which the diamine is dispersed or dissolved in the organic solvent is stirred, and the tetracarboxylic acid dianhydride is dispersed or dissolved in the organic solvent as it is, It is possible to use the method of. On the contrary, a method of adding a diamine to a solution in which a tetracarboxylic acid dianhydride is dispersed or dissolved in an organic solvent, a method of alternately adding a tetracarboxylic acid dianhydride and a diamine, and the like can be mentioned. In the present invention, any of these methods may be used. When the tetracarboxylic acid dianhydride and / or diamine is composed of a plurality of compounds, they may be reacted in a preliminarily mixed state, or they may be reacted individually in a sequential manner, or the low molecular weight compounds reacted individually are mixed and reacted, May be used.

The temperature at which the tetracarboxylic acid dianhydride is reacted with the diamine can be arbitrarily selected within the range of -20 to 150 占 폚, but it is preferably within the range of -5 to 100 占 폚 in consideration of the reaction efficiency. The reaction can be carried out at an arbitrary concentration. However, if the concentration is too low, it becomes difficult to obtain a polyimide precursor having a high molecular weight. On the other hand, if the concentration is too high, the viscosity of the reaction liquid becomes too high, and it becomes difficult to perform uniform stirring. Therefore, it is preferably 1 to 50 mass%, more preferably 5 to 30 mass%. It is also possible to carry out the reaction at a high concentration in the initial stage of the reaction, and then add an organic solvent.

When the tetracarboxylic acid dianhydride is reacted with the diamine, the ratio of the molar ratio of the tetracarboxylic acid dianhydride to the diamine is preferably 0.8 to 1.2. As in the case of a typical polycondensation reaction, the closer the molar ratio is to 1, the larger the degree of polymerization of the resulting polymer. If the degree of polymerization is too small, the strength of the polyimide varnish film formed by the polyimide varnish is insufficient, and if the degree of polymerization is too large, the workability in forming the polyimide coating film may be deteriorated.

Next, in the method for preparing a polyimide varnish of the present invention, a solution containing a polyimide precursor is obtained, and each of the solutions is mixed to obtain one reaction solution. If necessary, the solution containing the polyimide precursor is diluted with a suitable solvent such as the solvent described above, and each of the solutions is mixed to obtain one reaction solution. The concentration of the polyimide precursor in the reaction solution is preferably 1 to 12 mass%.

When the concentration of the polyimide precursor in the reaction solution is lower than 1% by mass, the interaction between the polyimide precursors is weakened. In the polyimide varnish thus obtained, sufficient printing property improving effect and difficulty in forming aggregates at the time of forming a coating film Is not sufficiently realized, and the filtering property at the time of recovery of the powdery polyimide obtained in the middle is deteriorated. When the concentration of the polyimide precursor in the reaction solution is higher than 12 mass%, the efficiency of purification decreases when the polyimide obtained by imidization is recovered. The concentration of the polyimide precursor in the reaction solution is more preferably 3 to 10 mass%, and still more preferably 5 to 8 mass%.

In the method for preparing the polyimide varnish of the present invention, it is preferable that the reaction solution obtained as described above is allowed to elapse for 10 minutes to 12 hours before imidizing the respective polyimide precursors in the reaction solution, as described later Do. If the elapsed time to the imidization after the reaction solution is obtained is shorter than 10 minutes, the sufficient polyimide varnish can not sufficiently realize the effect of improving the printability or the difficulty of forming an aggregate at the time of forming a coating film. If the elapsed time exceeds 12 hours, it takes too much time to prepare the polyimide varnish, which lowers the productivity of the polyimide varnish. The elapsed time up to the imidization after the reaction solution is obtained is more preferably 30 minutes to 6 hours, and further preferably 1 to 5 hours. After the reaction solution is obtained, stirring of the reaction solution is preferably carried out until imidization. When it is desired to shorten the elapsed time until the imidization after the reaction solution is obtained, it is preferable that the temperature of the reaction solution is set to be higher than the room temperature, for example, to the extent that imidization does not proceed.

Next, in the method for preparing the polyimide varnish of the present invention, the respective polyimide precursors in the reaction solution described above are imidized, and each polyimide precursor is converted into polyimide to obtain two or more kinds of polyimide derived from each polyimide precursor To obtain a polyimide solution. This polyimide solution is in a state in which two or more polyimides are dissolved in a solvent, and the polyimide varnish of the present invention can be used as it is.

In this case, the imidization rate (dehydration termination rate) of each polyimide precursor does not necessarily have to be 100%, but it is preferably 40 to 90%, more preferably 45 to 85% The range can be adjusted.

Examples of the method for imidizing the polyimide precursor include heat imidization in which the reaction solution containing the polyimide precursor is heated as it is, and catalyst imidization in which the catalyst is added to the reaction solution containing the polyimide precursor.

In the reaction solution containing the polyimide precursor, the temperature at which the thermal imidization is carried out is preferably from 100 to 400 ° C, more preferably from 120 to 250 ° C, while the water generated by the imidization reaction is removed from the reaction system .

The catalyst imidation of the polyimide precursor can be carried out by adding a basic catalyst and an acid anhydride to the reaction solution containing the polyimide precursor and stirring at -20 to 250 ° C, preferably 0 to 180 ° C. The amount of the basic catalyst is 0.5 to 30 moles, preferably 2 to 20 moles, of the amide acid group, and the amount of the acid anhydride is 1 to 50 moles, preferably 3 to 30 moles, of the amide acid group.

Examples of the basic catalyst include pyridine, triethylamine, trimethylamine, tributylamine, trioctylamine, and the like. Of these, pyridine is preferable in that it has an appropriate basicity for promoting the reaction. As the acid anhydride, acetic anhydride, trimellitic anhydride, pyromellitic anhydride and the like can be given, and acetic anhydride is particularly preferable since purification after completion of the reaction is facilitated. The imidization rate by the catalyst imidization can be controlled by adjusting the catalyst amount, the reaction temperature and the reaction time.

Next, in the method for preparing a polyimide varnish of the present invention, the polyimide is preferably recovered from the obtained polyimide solution. The recovered polyimide is, for example, a powdery polyimide, and contains two or more polyimides having different structures corresponding to each of two or more kinds of polyimide precursors having different structures used.

In the case of recovering the polyimide, the polyimide solution may be put into a poor solvent for precipitation. Examples of the poor solvent used in the precipitation include methanol, acetone, hexane, butyl cellosolve, heptane, methyl ethyl ketone, methyl isobutyl ketone, ethanol, toluene, benzene and water. The polymer precipitated by charging into a poor solvent can be recovered by filtration and then dried at normal temperature or under reduced pressure at room temperature or by heating. In addition, when the polymer precipitated and recovered is redissolved in an organic solvent and the operation of reprecipitation and recovery is repeated 2 to 10 times, impurities in the polymer can be reduced. Examples of the poor solvent at this time include alcohols, ketones, hydrocarbons and the like, and it is preferable to use three or more poor solvents selected from these because the purification efficiency is further increased. Thus, two or more types of polyimide are contained to obtain purified powdery polyimide.

The molecular weight of each polyimide contained in the powdery polyimide is determined by the weight average molecular weight measured by GPC (Gel Permeation Chromatography) method, taking into consideration the strength of the film obtained by using the same, the workability at the time of forming a coating film and the uniformity of the coating film It is preferably from 5000 to 1000000, and more preferably from 10,000 to 150,000.

Next, in the method of preparing the polyimide varnish of the present invention, the powdery polyimide containing the recovered two or more kinds of polyimide can be obtained by reacting a polyimide powder in a solvent usable for the synthesis reaction of the polyimide precursor Soluble in a solvent. In the method for preparing a polyimide varnish of the present invention, a polyimide varnish can be prepared by dissolving two or more types of polyimide in a solvent.

Next, another example of a method for preparing polyimide varnish containing two or more kinds of polyimide of the present invention will be described.

In another example of the method for preparing a polyimide varnish of the present invention, a solution containing a polyimide precursor corresponding to each of two or more types of polyimide to be initially contained is prepared separately at the time of preparation of the polyimide varnish do. The polyimide precursors contained in each solution are formed from different combinations of tetracarboxylic acid dianhydrides or derivatives thereof and diamines and have different structures from each other.

First, for each of the solutions containing the polyimide precursor, imidization of the contained polyimide precursor is carried out. In this case, the imidization rate of the polyimide precursor varies depending on the purpose and purpose, but is preferably adjusted in the range of 40 to 90%, more preferably 45 to 85%. Two or more kinds of polyimides corresponding to the kind of the polyimide precursor are recovered, for example, in powder form.

Subsequently, the recovered plural kinds of powdery polyimides are mixed to obtain a mixed polyimide powder. It is preferable to mix such plural kinds of powdery polyimides as much as possible. For this reason, a mixing means such as stirring for 15 minutes or more with a stirrer or the like is used.

Then, the polyimide varnish of the present invention in which two or more kinds of polyimides are dissolved can be prepared by dissolving the obtained mixed polyimide powder in a solvent.

Another method of preparing the polyimide varnish of the present invention is a method of preparing two or more kinds of powdery polyimides separately and then mixing to obtain a mixed polyimide powder and then dissolving it in a solvent to prepare two or more poly To prepare a polyimide varnish in a state in which the polyimide is dissolved in a solvent. Two or more kinds of powdery polyimides are formed in different combinations of tetracarboxylic acid dianhydrides or derivatives thereof and diamines, and have different structures from each other.

As the solvent for dissolving the polyimide in powder form, N-methyl-2-pyrrolidone,? -Butyrolactone and the like are used.

In another example of the method of preparing the polyimide varnish of the present invention, the same tetracarboxylic acid dianhydrides and diamines as the selectable polyimide varnish can be used. Then, in the same manner as in the above-described method for preparing a polyimide varnish, a solution containing the polyimide precursor can be similarly prepared by reacting them.

The imidization of the polyimide precursor contained in each solution can be carried out in the same manner as the imidization in the reaction solution in the above-described method of preparing the polyimide varnish. The same can be applied to the recovery of polyimide. After obtaining the mixed polyimide powder using the recovered powdery polyimide powder, the mixed polyimide powder such as a solvent usable for the synthesis reaction of the polyimide precursor is dissolved and dispersed in the same manner as the above-described method for preparing the polyimide varnish Lt; / RTI &gt; In another example of the method for preparing a polyimide varnish of the present invention, a polyimide varnish of another example can be prepared while two or more polyimides are dissolved in a solvent.

[Liquid crystal aligning agent]

The liquid crystal aligning agent of the present invention is produced by using the polyimide varnish obtained by the method for preparing the polyimide varnish of the present invention. That is, the polyimide varnish obtained by the method of preparing the polyimide varnish of the present invention can be used as the liquid crystal aligning agent of the present invention as it is.

The liquid crystal aligning agent of the present invention may also be prepared by diluting the polyimide varnish obtained by the method for preparing a polyimide varnish of the present invention with a suitable solvent to be described later.

The liquid crystal aligning agent of the present invention may also be produced by further adding an additive to be described later to the polyimide varnish obtained by the method for preparing a polyimide varnish of the present invention.

The liquid crystal aligning agent of the present invention is a coating liquid for forming a liquid crystal alignment film used in a liquid crystal display element and is a solution in which a polymer such as polyimide contained in the polyimide varnish is dissolved in a solvent. The liquid crystal aligning agent of the present invention suppresses generation of agglomerates and is excellent in printing property.

The solid content concentration in the liquid crystal aligning agent of the present invention can be suitably changed according to the setting of the thickness of the liquid crystal alignment film formed using the same, but is preferably 0.5 to 10 mass%, more preferably 1 to 8 mass% Do. When the solid concentration is less than 0.5 mass%, it is difficult to form a uniform and defect-free coating film, while when it is more than 10 mass%, the storage stability of the solution may be deteriorated. The term "solid component" as used herein refers to a component from which a solvent is removed from a liquid crystal aligning agent, and means a polymer such as the above-mentioned polyimide or the like and additives described below.

The method for producing the liquid crystal aligning agent of the present invention is not particularly limited.

The polyimide varnish obtained by the process for preparing a polyimide varnish of the present invention can be used and, if necessary, it can be prepared by diluting it with a solvent to a desired concentration.

The solvent usable in the production of the liquid crystal aligning agent of the present invention is not particularly limited as long as it is a solvent for dissolving the resin component. Specific examples thereof are given below.

Specific examples of usable solvents include N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methylcaprolactam, 2- 3-methoxy-N, N-dimethylpropanamide, 3-methoxy-N, N-dimethylacetamide, N, N-dimethylformamide, N, N-dimethylformamide, N-methylpyrrolidone, N-vinylpyrrolidone, dimethylsulfoxide, tetramethylurea, pyridine, dimethylsulfone, hexamethylsulfoxide, N, N-dimethylpropanamide, 1,3-dimethyl-imidazolidinone, ethyl amyl ketone, methyl nonyl ketone, methyl ethyl ketone, methyl Methyl isopropyl ketone, cyclohexanone, ethylene carbonate, propylene carbonate, diglyme, 4-hydroxy-4-methyl-2-pentanone and the like. These may be used alone or in combination.

The content of the solvent in the liquid crystal aligning agent is 90 to 99% by mass, preferably 92 to 98% by mass with respect to the total amount (100% by mass) of the liquid crystal aligning agent.

The liquid crystal aligning agent of the present invention may contain an additive. Examples of the additive include a solvent or a compound that improves film thickness uniformity or surface smoothness when the liquid crystal aligning agent is applied, a compound that improves adhesion between the formed liquid crystal alignment film and the substrate, an antioxidant that improves thermal stability, And a light stabilizer that improves the light transmittance.

Specific examples of the solvent (poor solvent) for improving the uniformity of the film thickness and the surface smoothness include the following.

Examples of the solvent include isopropyl alcohol, methoxymethyl pentanol, methyl cellosolve, ethyl cellosolve, butyl cellosolve, methyl cellosolve acetate, ethyl cellosolve acetate, butyl carbitol, ethyl carbitol, ethyl But are not limited to, carbitol acetate, carbitol acetate, ethylene glycol, ethylene glycol monoacetate, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, propylene glycol, propylene glycol monoacetate, propylene glycol monomethyl ether, Monomethyl ether, diethylene glycol, diethylene glycol monoacetate, diethylene glycol dimethyl ether, dipropylene glycol monoacetate monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monoacetate monoethyl Ether, dipropylene glycol monopro Methyl ether, dipropylene glycol monoacetate monopropyl ether, 3-methyl-3-methoxybutyl acetate, tripropylene glycol methyl ether, 3-methyl-3-methoxybutanol, diisopropyl ether, ethyl isobutyl ether, di Propyl ether, dihexyl ether, 1-hexanol, n-pentane, n-pentane, n-octane, diethyl ether , Methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, n-butyl acetate, propylene glycol monoethyl ether acetate, methyl pyruvate, ethyl pyruvate, methyl 3-methoxypropionate, methylethyl 3-ethoxypropionate, Methoxypropionate, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, 1-ethoxy-2-propanol, Propoxy Propylene glycol monoacetate, propylene glycol diacetate, propylene glycol-1-monomethyl ether-2-acetate, propylene glycol-1-monoethyl ether-2-acetate, dipropylene glycol, And a solvent having a low surface tension such as 2- (2-ethoxypropoxy) propanol, lactic acid methyl ester, lactic acid ethyl ester, n-propyl lactate, n-butyl lactate, .

These poor solvents may be used alone or in combination. When such a solvent is used, it is preferably 5 to 80 mass%, more preferably 20 to 60 mass%, of the total solvent contained in the liquid crystal aligning agent.

Examples of the compound that improves film thickness uniformity and surface smoothness include a fluorine-based surfactant, a silicon-based surfactant, and a nonionic surface-active agent.

More specifically, for example, EF301, EF303, EF352 (manufactured by TOKEM PRODUCTS CO., LTD.), Megapack (registered trademark) F171, F173, R-30 (manufactured by Dainippon Ink & (Trade name) manufactured by Asahi Glass Co., Ltd.), FC430, FC431 (manufactured by Sumitomo 3M Co., Ltd.), Asahi Guard (registered trademark) AG710, Surflon (registered trademark) S-382, SC101, SC102, SC103, SC104, SC105, SC106 . The ratio of these surfactants to be used is preferably 0.01 to 2 parts by mass, more preferably 0.01 to 1 part by mass based on 100 parts by mass of the polymer component contained in the liquid crystal aligning agent.

Specific examples of the compound improving the adhesion between the liquid crystal alignment layer and the substrate include the following functional silane-containing compounds and epoxy group-containing compounds.

For example, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 2-aminopropyltrimethoxysilane, 2-aminopropyltriethoxysilane, N- (2-aminoethyl) -3 3-aminopropylmethyldimethoxysilane, 3-ureidopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, N-ethoxy (3-aminopropyl) Aminopropyltriethoxysilane, N-trimethoxysilylpropyltriethoxysilane, N-trimethoxysilylpropyltriethoxysilane, N-trimethoxysilylpropyltriethoxysilane, N-trimethoxysilylpropyltriethoxysilane, Amine, 10-trimethoxysilyl-1,4,7-triazadecane, 10-triethoxysilyl-1,4,7-triazadecane, 9-trimethoxysilyl-3,6-diazanonyl Acetate, 9-triethoxysilyl-3,6-diazanonyl acetate, N-benzyl-3-aminopropyltrimethoxysilane, N-benzyl-3-aminopropyltriethoxysilane, N- Bis (oxyethylene) -3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltriethoxysilane, N- Aminopropyltriethoxysilane, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, neo Pentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerin diglycidyl ether, 2,2-dibromoneopentyl glycol diglycidyl ether, 1,3,5,6 Tetraglycidyl-2,4-hexanediol, N, N, N ', N', -tetraglycidyl-m-xylylenediamine, 1,3-bis (N, N-diglycidylamino Methyl) cyclohexane, N, N, N ', N', -tetraglycidyl-4,4'-diaminodiphenylmethane and the like.

Specific examples of the compound that improves thermal stability include the following phenolic compounds and the like.

For example, 2,6-di-tert-butyl-p-cresol, 2,6-di-tert- butylphenol, 2,4,6-tris (3 ', 5'- Hydroxybenzyl) mesitylene, pentaerythritol tetrakis [3- (3 ', 5'-di-tert-butyl-4'-hydroxyphenyl) propionate], acetone bis (3,5- Di-tert-butyl-4-hydroxyphenyl) mercapol, 4,4'-methylenebis (2,6- Hydroxyphenyl) propionate, 4,4'-thiodi (2,6-di-tert-butylphenol), tris (3,5- Bis (3,5-di-tert-butyl-4-hydroxybenzyl) sulfide.

Examples of the compound that improves light resistance include hindered amine compounds shown below.

For example, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, Bis (1,1-dimethylethyl) -4-hydroxyphenyl] methyl] butyl malonate, 1 4- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy] ethyl] -4- [3- Propoxyphenyl) propionyloxy] -2,2,6,6-tetramethylpiperidine, and the like.

[Liquid crystal alignment film and liquid crystal display element]

The liquid crystal aligning agent of the present invention can be applied to a substrate and dried and fired to form a coating film. The liquid crystal alignment film can be formed by subjecting the coated film surface to an orientation treatment such as rubbing treatment or light irradiation. It is preferable to filter the liquid crystal aligning agent before applying it to the substrate.

The liquid crystal aligning agent of the present invention is excellent in printability while suppressing the generation of aggregates, and the liquid crystal alignment film formed therefrom is excellent in in-plane uniformity in properties such as film thickness and the like as a liquid crystal alignment film.

When the liquid crystal aligning agent of the present invention is applied to a substrate, a substrate having high transparency can be used as the substrate to be used. As such a substrate, for example, in addition to a glass substrate, a plastic substrate such as an acrylic substrate or a polycarbonate substrate can be used.

When the liquid crystal aligning agent of the present invention is used in the production of a liquid crystal display element, it is preferable to form a liquid crystal alignment film by using a substrate on which an ITO (Indium Tin Oxide) electrode for liquid crystal driving is formed. When a reflection type liquid crystal display device is manufactured, an opaque substrate such as a silicon wafer can be used as long as it is a substrate on only one side. In this case, a material that reflects light such as aluminum may be used as the electrode in this case.

The method of applying the liquid crystal aligning agent of the present invention on a substrate is not particularly limited, but industrially, screen printing, offset printing, flexographic printing, or inkjet printing are common methods. Examples of other coating methods include a dipping method, a roll coater method, a slit coater method, a spinner method, and a spraying method, and they may be used depending on the purpose.

The liquid crystal aligning agent of the present invention has good applicability even when the above coating method is used.

The drying process after coating the liquid crystal aligning agent is not necessarily required, but it is preferable that the drying process is included when the time from the application to the firing is not constant from substrate to substrate or when the substrate is not fired immediately after coating. The drying is not particularly limited as long as the solvent is evaporated to such an extent that the shape of the coated film is not deformed by transporting the substrate or the like. To give concrete examples, a method of drying on a hot plate at 50 to 150 ° C, preferably 80 to 120 ° C, for 0.5 to 30 minutes, preferably 1 to 5 minutes may be mentioned.

The baking of the substrate coated with the liquid crystal aligning agent can be carried out at any temperature of 100 to 350 ° C by heating means such as a hot plate, a heat circulation type oven, and an IR (infrared) type oven. The firing temperature is preferably 150 to 300 占 폚, and more preferably 180 to 250 占 폚. However, it is preferable that the baking is performed at a temperature higher by 10 DEG C or more than the heat treatment temperature such as seal hardening, which is required in the process of manufacturing a liquid crystal display device.

When the thickness of the coated film after firing is too large, the power consumption of the liquid crystal display element is deteriorated. When the thickness is too thin, the reliability of the liquid crystal display element may be deteriorated. Therefore, the thickness is preferably 10 to 200 nm, more preferably 50 To 100 nm.

Conventional rubbing apparatuses can be used for rubbing the coating film surface formed on the substrate as described above. The material of the rubbing cloth at this time may be cotton, rayon, nylon, and the like.

By using the liquid crystal aligning agent of the present invention, a liquid crystal display element can be produced by a known method after obtaining a substrate on which a liquid crystal alignment film is formed by the above-mentioned technique.

An example of the production of a liquid crystal display element will be described next.

A pair of substrates having a liquid crystal alignment film formed using the liquid crystal aligning agent of the present invention are prepared. Then, the pair of substrates are placed so as to have an arbitrary angle of 0 to 270 deg. In the rubbing direction with a spacer of preferably 1 to 30 mu m, more preferably 2 to 10 mu m interposed therebetween, To zero. Subsequently, liquid crystal is injected between the substrates and sealed. The method of enclosing the liquid crystal is not particularly limited, and examples thereof include a vacuum method in which liquid crystals are injected after reducing the pressure in the produced liquid crystal cell, and a dropping method in which the liquid crystal is dripped and sealed.

The liquid crystal display element thus produced has a liquid crystal alignment layer formed from the liquid crystal aligning agent of the present invention and has no gap unevenness between the substrates which sandwich the liquid crystal and has excellent display quality and high reliability.

Example

Hereinafter, the present invention will be described in further detail with reference to examples. The present invention is not limited to these examples.

The abbreviations of the compounds used in Examples and Comparative Examples are as follows.

&Lt; Tetracarboxylic acid dianhydride &gt;

CBDA: 1,2,3,4-Cyclobutane tetracarboxylic acid dianhydride

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

PMDA: pyromellitic acid dianhydride

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

TCA: 2,3,5-tricarboxycyclopentylacetic acid dianhydride

<Diamine>

4ABA: 4-aminobenzylamine

3ABA: 3-aminobenzylamine

2,4-DAA: 2,4-diamino-N, N-diallylamine

APC12: 1,3-Diamino-4-dodecyloxybenzene

APC18: 1,3-Diamino-4-octadecyloxybenzene

TPBP-2: 4- (trans-4-pentylcyclohexyl) benzamide 2 ', 4'-Phenylenediamine

p-PDA: p-phenylenediamine

Me-3ABA: 3 - ((N-methylamino) methyl) aniline

DABFr: 3,5-diaminobenzyl-2-

PCH7AB: 4- (trans-4-n-heptylcyclohexyl) -2,4-diaminobenzene

DDM: 4,4'-diaminodiphenylmethane

<Solvent>

NMP: N-methyl-2-pyrrolidone

GBL:? -Butyrolactone

BCS: butyl cellosolve

Various measuring methods and evaluation methods in the examples will be described below.

&Lt; Measurement of molecular weight &

The molecular weights of the polyamic acid and the polyimide were measured by a GPC (room temperature gel permeation chromatography) apparatus and the number average molecular weight and the weight average molecular weight were calculated as polyethylene glycol and polyethylene oxide conversion values.

GPC apparatus: manufactured by Shodex Corp. (GPC-101)

Column: manufactured by Shodex Co., Ltd. (serial of KD803, KD805)

Column temperature: 50 ° C

Eluent: N, N-dimethylformamide (30 millimoles / liter of lithium bromide-hydrate (LiBr.H ₂ O), 30 millimoles / liter of phosphoric anhydride crystal (o-phosphoric acid) Furan (THF) of 10 ml / l)

Flow rate: 1.0 ml / min

Standard samples for preparing a calibration curve: TSK standard polyethylene oxide (molecular weight about 900000, 150000, 100000, and 30000) manufactured by Tosoh Corporation and polyethylene glycol (molecular weight about 12000, 4000, and 1000) manufactured by Polymer Laboratories.

&Lt; Measurement of imidization rate &

The imidization rate of the polyimide was measured in the following manner.

20 mg of the polyimide powder was placed in an NMR sample tube, and 0.53 ml of deuterated dimethyl sulfoxide (DMSO-d ₆ , 0.05 mass% TMS (tetramethylsilane) mixture) was added to dissolve completely. The proton NMR at 500 MHz of this solution was measured with an NMR meter (JNM-ECA500) manufactured by Nippon Denshoku. A proton originating from a structure which does not change before and after imidation is defined as a reference proton and the proton peak integrated value derived from the NH group of the amic acid appearing in the vicinity of 9.5 to 10.0 ppm By using the following equation.

Imidization ratio (%) = (1 -? X / y) x 100

In the above formula, x is the proton peak integrated value derived from the NH group of amic acid, y is the peak integrated value of the reference proton, and? Is the NH group of the amic acid in the case of the polyamic acid (the imidization rate is 0% The ratio of the number of reference protons to one proton.

&Lt; Evaluation of agglomeration time &

About 0.1 ml of each polyimide varnish of the examples and comparative examples was dropped on a Cr substrate and left in an environment at a temperature of 23 占 폚 and a humidity of 45%. The vicinity of the end of the droplet was observed with a microscope every 10 minutes. In addition, observation was carried out at a magnification of 100 times. The time at which the agglomerates were generated was evaluated as the agglomeration start time, and the evaluation results of the polyimide varnishes of Examples and Comparative Examples are summarized in Table 1.

(Synthesis Example 1)

19.86 g (0.101 mol) of CBDA, 9.81 g (0.045 mol) of PMDA, 5.50 g (0.045 mol) of 4ABA as a diamine and 12.20 g (0.060 mol) of 2,4-DAA as a tetracarboxylic acid dianhydride component, And 13.16 g (0.045 mol) of APC12 were reacted in 242.1 g of NMP at room temperature for 18 hours to obtain a solution of 20 mass% of polyamic acid (PAA-1). The viscosity of this polyamic acid solution at 25 캜 was 597 mPa s. The molecular weight of this polyamic acid was Mn = 14224 and Mw = 36140.

(Synthesis Example 2)

21.84 g (0.111 mol) of CBDA, 4.42 g (0.020 mol) of PMDA, 3.30 g (0.027 mol) of 3ABA as diamine and 13.72 g (0.067 mol) of 2,4-DAA as tetracarboxylic acid dianhydride components, , 16.51 g (0.041 mol) of TPBP and 239.1 g of NMP were reacted at room temperature for 22 hours to obtain a solution having a concentration of polyamic acid (PAA-2) of 20 mass%. The viscosity of this polyamic acid solution at 25 캜 was 693 mPa s. The molecular weight of this polyamic acid was Mn = 20366 and Mw = 54052.

(Synthesis Example 3)

PDA was used as the diamine component, and 5.27 g (0.014 mol) of APC 18 was used as the tetracarboxylic acid dianhydride component, and 41.62 g (0.139 mol) of TDA, For 20 hours to obtain a solution having a concentration of polyamic acid (PAA-3) of 20 mass%. The viscosity of this polyamic acid solution at 25 캜 was 948 mPa s. The molecular weight Mn of this polyamic acid was 11244 and Mw = 22915.

(Synthesis Example 4)

4.61 g (0.024 mol) of CBDA, 6.26 g (0.025 mol) of BODA, 2.97 g (0.027 mol) of p-PDA as a diamine component and 1.83 g (0.015 mol) of 3ABA as a tetracarboxylic acid dianhydride component, 3.06 g (0.008 mol) of TPBP and 74.91 g of NMP were reacted at room temperature for 2 hours to obtain a solution having a concentration of polyamic acid (PAA-4) of 20 mass%. The viscosity of this polyamic acid solution at 25 캜 was 967 mPa s. The molecular weight Mn of this polyamic acid was 10845 and Mw = 26494.

(Synthesis Example 5)

9.51 g (0.048 mol) of CBDA as a tetracarboxylic acid dianhydride component, 4.77 g (0.035 mol) of Me-3ABA as a diamine component, 2.32 g (0.010 mol) of DABFr and 2.04 g ) And reacted in 74.6 g of NMP at room temperature for 2 hours to obtain a solution having a concentration of polyamic acid (PAA-5) of 20 mass%. The viscosity of this polyamic acid solution at 25 캜 was 584 mPa.. The molecular weight Mn of this polyamic acid was 11142 and Mw = 32633.

(Synthesis Example 6)

10.87 g (0.048 mol) of TCA as a tetracarboxylic acid dianhydride component, 4.33 g (0.040 mol) of p-PDA as a diamine component and 3.81 g (0.010 mol) of PCH7AB were used, (PAA-6) solution with a concentration of 20 wt%. The viscosity of the polyamic acid solution at 25 캜 was 685 mPa s. The molecular weight Mn of this polyamic acid was 11742 and Mw = 23111.

(Synthesis Example 7)

(Polylactic acid (PAA-7) was obtained by reacting 14.87 g (0.049 mol) of TDA as a tetracarboxylic acid dianhydride component and 9.91 g (0.05 mol) of DDM as a diamine component in 74.6 g of NMP at 50 DEG C for 20 hours. ) Concentration of 20 wt%. The viscosity of the polyamic acid solution at 25 캜 was 483 mPa.. The molecular weight Mn of this polyamic acid was 9835 and Mw = 20694.

(Example 1)

To 276.9 g of the polyamic acid solution (PAA-1) obtained in the same manner as in Synthesis Example 1, 378.1 g of NMP was added and diluted to prepare a polyamic acid solution (PAA-1-2) having a concentration of 8 mass%. Then, 401.6 g of NMP was added to 271.5 g of the polyamic acid solution (PAA-2) obtained in the same manner as in Synthesis Example 2 to dilute the polyamic acid solution (PAA-2-2) at a concentration of 8% by mass.

Subsequently, 315.0 g of PAA-1-2 and 135.0 g of PAA-2-2 were mixed. To this mixture solution (450.0 g) were added 24.73 g of acetic anhydride and 10.54 g of pyridine, followed by reaction at 50 ° C for 2 hours It was light. The obtained polyimide solution was cooled to room temperature and then charged into 1698 g of methanol, and the precipitated solid was recovered. Further, this solid was washed twice with methanol, and then dried under reduced pressure at 100 占 폚 to obtain an ocher-colored powder of polyimide (SPI-1). The polyimide had a number average molecular weight of 11529 and a weight average molecular weight of 31363. The imidization rate was 87%.

To 11.0 g of the obtained polyimide (SPI-1), 80.7 g of GBL was added and the mixture was stirred at 50 占 폚 for 20 hours. At the end of the stirring, the polyimide was completely dissolved. 23.8 g of GBL, 41.8 g of NMP and 62.7 g of BCS were added to this solution, and the mixture was stirred at 50 占 폚 for 20 hours to obtain a mixture containing 5.0 mass% of solid content (SPI-1), 47.5 mass% of GBL, 19.0 mass %, And a polyimide varnish having a BCS of 28.5% by mass. This polyimide varnish can be used as a liquid crystal aligning agent for forming a liquid crystal alignment film as it is. The agitation start time of the obtained polyimide varnish was evaluated according to the above-described evaluation method. The evaluation results are shown in Table 1.

(Example 2)

To 22.0 g of the polyamic acid solution (PAA-3) obtained in the same manner as in Synthesis Example 3, 33.0 g of NMP was added and diluted to prepare a polyamic acid solution (PAA-3-2) having a concentration of 8 mass%. Next, 220.0 g of the polyamic acid solution (PAA-1-2) obtained in the same manner as in Example 1 was mixed with 55.0 g of PAA-3-2. To 275.0 g of the mixed solution, 50.13 g of acetic anhydride and 23.31 g of pyridine And the mixture was allowed to react at 40 ° C for 3 hours to imidize. The obtained polyimide solution was cooled to room temperature, and then charged into 1186 g of methanol, and the precipitated solid was recovered. This solid was washed twice with methanol and then dried under reduced pressure at 100 占 폚 to obtain an ocher-colored powder of polyimide (SPI-2). The polyimide had a number average molecular weight of 9967 and a weight average molecular weight of 24637. The imidization rate was 94%.

To 11.0 g of the obtained polyimide (SPI-2), 80.7 g of GBL was added and the mixture was stirred at 50 占 폚 for 20 hours. At the end of the stirring, the polyimide was completely dissolved. To this solution, 23.7 g of GBL, 73.2 g of NMP and 31.4 g of BCS were added and stirred at 50 占 폚 for 20 hours to obtain 5.0 mass% of solid content (SPI-2), 47.4 mass% of GBL, 33.3 mass %, And a polyimide varnish having a BCS of 14.3 mass%. This polyimide varnish can be used as a liquid crystal aligning agent for forming a liquid crystal alignment film as it is. The agitation start time of the obtained polyimide varnish was evaluated according to the above-described evaluation method. The evaluation results are shown in Table 1.

(Example 3)

To 15.0 g of the polyamic acid solution (PAA-4) obtained in the same manner as in Synthesis Example 4, 22.5 g of NMP was added and diluted to prepare a polyamic acid solution (PAA-4-2) having a concentration of 8 mass%. Next, 87.5 g of the polyamic acid solution (PAA-1-2) obtained in the same manner as in Example 1 was mixed with 37.5 g of PAA-4-2. To 125.0 g of this mixed solution, 13.26 g of acetic anhydride and 10.28 g of pyridine And the mixture was allowed to react at 50 DEG C for 2 hours to imidize. The obtained polyimide solution was cooled to room temperature and then charged into 509 g of methanol, and the precipitated solid was recovered. Further, this solid was washed twice with methanol, and then dried under reduced pressure at 100 占 폚 to obtain an ocher-colored powder of polyimide (SPI-3). The polyimide had a number average molecular weight of 5185 and a weight average molecular weight of 20,781. The imidization rate was 50%.

To 7.0 g of the obtained polyimide (SPI-3), 58.3 g of GBL was added and the mixture was stirred at 50 占 폚 for 20 hours. At the end of the stirring, the polyimide was completely dissolved. To this solution, 8.2 g of GBL, 26.6 g of NMP and 39.9 g of BCS were added and stirred at 50 占 폚 for 20 hours to obtain 5.0 mass% of solids (SPI-3), 47.5 mass% of GBL, 19.0 mass %, And a polyimide varnish having a BCS of 28.5% by mass. This polyimide varnish can be used as a liquid crystal aligning agent for forming a liquid crystal alignment film as it is. The agitation start time of the obtained polyimide varnish was evaluated according to the above-described evaluation method. The evaluation results are shown in Table 1.

(Example 4)

To 15.0 g of the polyamic acid solution (PAA-5) obtained in the same manner as in Synthesis Example 5, 22.5 g of NMP was added and diluted to prepare a polyamic acid solution (PAA-5-2) having a concentration of 8 mass%. Next, 87.5 g of the polyamic acid solution (PAA-1-2) obtained in the same manner as in Example 1 was mixed with 37.5 g of PAA-5-2. To 125.0 g of this mixed solution, 13.31 g of acetic anhydride and 10.31 g of pyridine And the mixture was allowed to react at 50 DEG C for 2 hours to imidize. The obtained polyimide solution was cooled to room temperature and then charged into 513 g of methanol, and the precipitated solid was recovered. Further, this solid was washed twice with methanol, and then dried under reduced pressure at 100 占 폚 to obtain an ocher-colored powder of polyimide (SPI-4). The polyimide had a number average molecular weight of 9996 and a weight average molecular weight of 26884. The imidization rate was 65%.

58.3 g of GBL was added to 7.0 g of the obtained polyimide (SPI-4), and the mixture was stirred at 50 占 폚 for 20 hours. At the end of the stirring, the polyimide was completely dissolved. To this solution, 8.2 g of GBL, 26.6 g of NMP and 39.9 g of BCS were added and stirred at 50 占 폚 for 20 hours to obtain 5.0 mass% of solids (SPI-4), 47.5 mass% of GBL, 19.0 mass %, And a polyimide varnish having a BCS of 28.5% by mass. This polyimide varnish can be used as a liquid crystal aligning agent for forming a liquid crystal alignment film as it is. The agitation start time of the obtained polyimide varnish was evaluated according to the above-described evaluation method. The evaluation results are shown in Table 1.

(Example 5)

21.08 g of acetic anhydride and 8.99 g of pyridine were added to 350.0 g of the polyamic acid solution (PAA-1-2) obtained in the same manner as in Example 1, and the mixture was reacted at 50 DEG C for 2 hours to imidate. The obtained polyimide solution was cooled to room temperature and then charged into 1330 g of methanol, and the precipitated solid was recovered. Further, this solid was washed twice with methanol, and then dried under reduced pressure at 100 占 폚 to obtain an ocher-colored powder of polyimide (SPI-5). The polyimide had a number average molecular weight of 10920 and a weight average molecular weight of 31108. The imidization rate was 80%.

22.26 g of acetic anhydride and 9.49 g of pyridine were added to 400.0 g of the polyamic acid solution (PAA-2-2) obtained in the same manner as in Example 1, and the mixture was allowed to react at 50 ° C for 2 hours to imidize. The obtained polyimide solution was cooled to room temperature and then charged into 1511 g of methanol, and the precipitated solid was recovered. Further, this solid was washed twice with methanol, and then dried under reduced pressure at 100 占 폚 to obtain an ocher-colored powder of polyimide (SPI-6). The polyimide had a number average molecular weight of 13306 and a weight average molecular weight of 35,615. The imidization rate was 100%.

Then, 7.7 g of SPI-5 and 3.3 g of SPI-6 were mixed, 80.7 g of GBL was added, and the mixture was stirred at 50 占 폚 for 20 hours. At the end of the stirring, the polyimide was completely dissolved. Further, 23.8 g of GBL, 41.8 g of NMP and 62.7 g of BCS were added to this solution, and the mixture was stirred at 50 占 폚 for 20 hours to obtain a solid content (SPI-5 + SPI-6) of 5.0% by mass, a GBL of 47.5% A polyimide varnish having an NMP of 19.0 mass% and a BCS of 28.5 mass% was obtained. This polyimide varnish can be used as a liquid crystal aligning agent for forming a liquid crystal alignment film as it is. The agitation start time of the obtained polyimide varnish was evaluated according to the above-described evaluation method. The evaluation results are shown in Table 1.

(Example 6)

52.68 g of acetic anhydride and 24.50 g of pyridine were added to 110.0 g of the polyamic acid solution (PAA-1-2) obtained in the same manner as in Example 1, and the mixture was reacted at 40 ° C for 3 hours to imidate. The obtained polyimide solution was cooled to room temperature and then charged into 1185 g of methanol, and the precipitated solid was recovered. Further, this solid was washed twice with methanol, and then dried under reduced pressure at 100 占 폚 to obtain an ocher-colored powder of polyimide (SPI-7). This polyimide had a number average molecular weight of 9781 and a weight average molecular weight of 24985. The imidization rate was 95%.

48.18 g of acetic anhydride and 22.41 g of pyridine were added to 100.0 g of the polyamic acid solution (PAA-3-2) obtained in the same manner as in Example 2, and the mixture was reacted at 40 占 폚 for 3 hours to imidize. The obtained polyimide solution was cooled to room temperature and then poured into 1140 g of methanol, and the precipitated solid was recovered. Further, this solid was washed twice with methanol, and then dried under reduced pressure at 100 占 폚 to obtain a white powder of polyimide (SPI-8). This polyimide had a number average molecular weight of 1,1262 and a weight average molecular weight of 2,6984. The imidization rate was 90%.

Then, 7.7 g of SPI-7 and 3.3 g of SPI-8 were mixed, 80.7 g of GBL was added, and the mixture was stirred at 50 占 폚 for 20 hours. At the end of the stirring, the polyimide was completely dissolved. To this solution, 23.7 g of GBL, 73.2 g of NMP and 31.4 g of BCS were added and stirred at 50 占 폚 for 20 hours to obtain 5.0 mass% of solids (SPI-7 + SPI-8), 47.4 mass% of GBL, And 33.3% by mass of BCS and 14.3% by mass of BCS, respectively. This polyimide varnish can be used as a liquid crystal aligning agent for forming a liquid crystal alignment film as it is. The agitation start time of the obtained polyimide varnish was evaluated according to the above-described evaluation method. The evaluation results are shown in Table 1.

(Example 7)

14.04 g of acetic anhydride and 10.88 g of pyridine were added to 50.0 g of the polyamic acid solution (PAA-4-2) obtained in the same manner as in Example 3, and the mixture was allowed to react at 50 ° C for 2 hours to imidize. The obtained polyimide solution was cooled to room temperature, and then poured into 539 g of methanol, and the precipitated solid was recovered. Further, this solid was washed twice with methanol, and then dried under reduced pressure at 100 占 폚 to obtain an ocher-colored powder of polyimide (SPI-9). This polyimide had a number average molecular weight of 5901 and a weight average molecular weight of 24,156. The imidization rate was 50%.

Next, 4.9 g of the polyimide (SPI-5) obtained in the same manner as in Example 5 and 2.1 g of SPI-9 were mixed, 58.3 g of GBL was added, and the mixture was stirred at 50 DEG C for 20 hours. At the end of the stirring, the polyimide was completely dissolved. Further, 8.2 g of GBL, 26.6 g of NMP and 39.9 g of BCS were added to this solution, and the mixture was stirred at 50 占 폚 for 20 hours to obtain a solid content (SPI-5 + SPI-9) of 5.0% by mass, GBL of 47.5% A polyimide varnish having an NMP of 19.0 mass% and a BCS of 28.5 mass% was obtained. This polyimide varnish can be used as a liquid crystal aligning agent for forming a liquid crystal alignment film as it is. The agitation start time of the obtained polyimide varnish was evaluated according to the above-described evaluation method. The evaluation results are shown in Table 1.

(Example 8)

14.45 g of acetic anhydride and 11.20 g of pyridine were added to 50.0 g of the polyamic acid solution (PAA-5-2) obtained in the same manner as in Example 4, and the mixture was allowed to react at 50 ° C for 2 hours to imidate. The obtained polyimide solution was cooled to room temperature and then charged into 559 g of methanol, and the precipitated solid was recovered. Further, this solid was washed twice with methanol, and then dried under reduced pressure at 100 占 폚 to obtain an ocher-colored powder of polyimide (SPI-10). The polyimide had a number average molecular weight of 11133 and a weight average molecular weight of 23773. The imidization rate was 65%.

Next, 4.9 g of the polyimide (SPI-5) obtained in the same manner as in Example 5 and 2.1 g of SPI-10 were mixed, 58.3 g of GBL was added, and the mixture was stirred at 50 占 폚 for 20 hours. At the end of the stirring, the polyimide was completely dissolved. To this solution, 8.2 g of GBL, 26.6 g of NMP and 39.9 g of BCS were added and stirred at 50 占 폚 for 20 hours to obtain 5.0 mass% of solid content (SPI-5 + SPI-10), 47.5 mass% of GBL, A polyimide varnish having an NMP of 19.0 mass% and a BCS of 28.5 mass% was obtained. This polyimide varnish can be used as a liquid crystal aligning agent for forming a liquid crystal alignment film as it is. The agitation start time of the obtained polyimide varnish was evaluated according to the above-described evaluation method. The evaluation results are shown in Table 1.

(Example 9)

To 22.0 g of the polyamic acid solution (PAA-6) obtained in the same manner as in Synthesis Example 6, 33.0 g of NMP was added and diluted to prepare a polyamic acid solution (PAA-6-2) having a concentration of 8 wt%. Next, 220.0 g of the polyamic acid solution (PAA-1-2) obtained in the same manner as in Example 1 was mixed with 55.0 g of PAA-6-2, and 27.07 g of acetic anhydride and 27.00 g of pyridine were added to 275.0 g of this mixed solution , And reacted at 40 ° C for 3 hours to imidize. The obtained polyimide solution was cooled to room temperature and then charged into 1260 g of methanol, and the precipitated solid was recovered. Further, this solid was washed twice with methanol, and then dried under reduced pressure at 100 占 폚 to obtain an ocher-colored powder of polyimide (SPI-11). The polyimide had a number average molecular weight of 10739 and a weight average molecular weight of 23009. The imidization rate was 87%.

To 11.0 g of the obtained polyimide (SPI-11), 80.7 g of GBL was added and the mixture was stirred at 50 DEG C for 20 hours. At the end of the stirring, the polyimide was completely dissolved. To this solution, 23.7 g of GBL, 73.2 g of NMP and 31.4 g of BCS were added and the mixture was stirred at 50 캜 for 20 hours to obtain a solid content (SPI-11) of 5.0 wt%, GBL of 47.4 wt%, NMP of 33.3 wt% A polyimide varnish having a BCS of 14.3 wt% was obtained. This polyimide varnish is directly used as a liquid crystal aligning agent for forming a liquid crystal alignment film. The agitation start time of the obtained polyimide varnish was evaluated according to the above-described evaluation method. The evaluation results are shown in Table 1.

(Example 10)

11.71 g of acetic anhydride and 5.45 g of pyridine were added to 50.0 g of the polyamic acid solution (PAA-6-2) obtained in the same manner as in Example 9, and the mixture was reacted at 50 ° C for 3 hours to imidize the solution. The obtained polyimide solution was cooled to room temperature and then charged into 187 g of methanol, and the precipitated solid was recovered. Further, this solid was washed twice with methanol, and then dried under reduced pressure at 100 占 폚 to obtain an ocher-colored powder of polyimide (SPI-12). This polyimide had a number average molecular weight of 9879 and a weight average molecular weight of 21571. [ The imidization rate was 86%.

Next, 8.8 g of SPI-5 and 2.2 g of SPI-12 were mixed, 80.7 g of GBL was added, and the mixture was stirred at 50 占 폚 for 20 hours. At the end of the stirring, the polyimide was completely dissolved. 5.0 wt% of solid content (SPI-5 + SPI-12), 47.4 wt% of GBL and 33.3 g of NMP were added to this solution and 23.7 g of GBL, 73.2 g of NMP and 31.4 g of BCS were added and stirred at 50 캜 for 20 hours. wt%, and BCS of 14.3 wt%. This polyimide varnish is directly used as a liquid crystal aligning agent for forming a liquid crystal alignment film. The agitation start time of the obtained polyimide varnish was evaluated according to the above-described evaluation method. The evaluation results are shown in Table 1.

(Example 11)

100.0 g of the polyamic acid solution (PAA-3-2) obtained in the same manner as in Example 2 and 100.0 g of the polyamic acid solution (PAA-5-2) obtained in the same manner as in Example 4 were mixed, 43.14 g of acetic anhydride and 20.06 g of pyridine were added and reacted at 50 캜 for 3 hours to imidate. The obtained polyimide solution was cooled to room temperature and then charged into 834 g of methanol, and the precipitated solid was recovered. Further, this solid was washed twice with methanol, and then dried under reduced pressure at 100 占 폚 to obtain an ocher-colored powder of polyimide (SPI-13). The polyimide had a number average molecular weight of 9986 and a weight average molecular weight of 20016. [ The imidization rate was 70%.

To 11.0 g of the obtained polyimide (SPI-13), 80.7 g of GBL was added and the mixture was stirred at 50 占 폚 for 20 hours. At the end of the stirring, the polyimide was completely dissolved. To this solution, 23.7 g of GBL, 73.2 g of NMP and 31.4 g of BCS were added and stirred at 50 캜 for 20 hours to obtain a solid content (SPI-13) of 5.0 wt%, GBL of 47.4 wt%, NMP of 33.3 wt% A polyimide varnish having a BCS of 14.3 wt% was obtained. This polyimide varnish is directly used as a liquid crystal aligning agent for forming a liquid crystal alignment film. The agitation start time of the obtained polyimide varnish was evaluated according to the above-described evaluation method. The evaluation results are shown in Table 1.

(Example 12)

5.5 g of the polyimide (SPI-8) obtained in the same manner as in Example 6 and 5.5 g of the polyimide (SPI-10) obtained in the same manner as in Example 8 were mixed and 80.7 g of GBL was added and stirred at 50 DEG C for 20 hours . At the end of the stirring, the polyimide was completely dissolved. To this solution, 23.7 g of GBL, 73.2 g of NMP and 31.4 g of BCS were added and stirred at 50 캜 for 20 hours to obtain a solid content (SPI-8 + SPI-10) of 5.0 wt%, GBL of 47.4 wt%, NMP of 33.3 wt%, and BCS of 14.3 wt%. This polyimide varnish is directly used as a liquid crystal aligning agent for forming a liquid crystal alignment film. The agitation start time of the obtained polyimide varnish was evaluated according to the above-described evaluation method. The evaluation results are shown in Table 1.

(Example 13)

To 40.0 g of the polyamic acid solution (PAA-7) obtained in the same manner as in Synthesis Example 7, 60.0 g of NMP was added and diluted to prepare a polyamic acid solution (PAA-7-2) having a concentration of 8 wt%. Next, 100.0 g of the polyamic acid solution (PAA-2-2) obtained in the same manner as in Example 1 was mixed with 100.0 g of PAA-7-2, 18.28 g of acetic anhydride and 14.17 g of pyridine were added to 200.0 g of this mixed solution And imidized by reacting at 50 ° C for 3 hours. The obtained polyimide solution was cooled to room temperature and then charged into 814 g of methanol, and the precipitated solid was recovered. Further, this solid was washed twice with methanol, and then dried under reduced pressure at 100 占 폚 to obtain an ocher-colored powder of polyimide (SPI-14). This polyimide had a number average molecular weight of 10917 and a weight average molecular weight of 22582. The imidization rate was 85%.

To 11.0 g of the obtained polyimide (SPI-14), 80.7 g of GBL was added and the mixture was stirred at 50 占 폚 for 20 hours. At the end of the stirring, the polyimide was completely dissolved. To this solution, 23.7 g of GBL, 73.2 g of NMP and 31.4 g of BCS were added and stirred at 50 占 폚 for 20 hours to obtain a solid content (SPI-14) of 5.0 wt%, GBL of 47.4 wt%, NMP of 33.3 wt% A polyimide varnish having a BCS of 14.3 wt% was obtained. This polyimide varnish is directly used as a liquid crystal aligning agent for forming a liquid crystal alignment film. The agitation start time of the obtained polyimide varnish was evaluated according to the above-described evaluation method. The evaluation results are shown in Table 1.

(Example 14)

16.38 g of acetic anhydride and 7.62 g of pyridine were added to 100.0 g of the polyamic acid solution (PAA-7-2) obtained in the same manner as in Example 13, and the mixture was reacted at 50 ° C for 3 hours to imidize the solution. The obtained polyimide solution was cooled to room temperature and then charged into 345 g of methanol, and the precipitated solid was recovered. Further, this solid was washed twice with methanol, and then dried under reduced pressure at 100 ° C to obtain an ocher-colored powder of polyimide (SPI-15). This polyimide had a number average molecular weight of 1,0003 and a weight average molecular weight of 2,093. The imidization rate was 83%.

Next, 5.5 g of the polyimide (SPI-6) obtained in the same manner as in Example 5 and 5.5 g of SPI-15 were mixed, 80.7 g of GBL was added, and the mixture was stirred at 50 캜 for 20 hours. At the end of the stirring, the polyimide was completely dissolved. To this solution, 23.7 g of GBL, 73.2 g of NMP and 31.4 g of BCS were added and stirred at 50 캜 for 20 hours to obtain a solid content (SPI-6 + SPI-15) of 5.0 wt%, GBL of 47.4 wt%, NMP of 33.3 wt%, and BCS of 14.3 wt%. This polyimide varnish is directly used as a liquid crystal aligning agent for forming a liquid crystal alignment film. The agitation start time of the obtained polyimide varnish was evaluated according to the above-described evaluation method. The evaluation results are shown in Table 1.

(Example 15)

100.0 g of the polyamic acid solution (PAA-4-2) obtained in the same manner as in Example 3 and 100.0 g of the polyamic acid solution (PAA-7-2) obtained in the same manner as in Example 13 were mixed, 22.46 g of acetic anhydride and 17.40 g of pyridine were added and reacted at 50 占 폚 for 3 hours to imidate. The obtained polyimide solution was cooled to room temperature and then charged into 840 g of methanol, and the precipitated solid was recovered. This solid was washed twice with methanol and dried under reduced pressure at 100 占 폚 to obtain an ocher-colored powder of polyimide (SPI-16). This polyimide had a number average molecular weight of 9765 and a weight average molecular weight of 21724. The imidization rate was 61%.

To 11.0 g of the obtained polyimide (SPI-16), 80.7 g of GBL was added and the mixture was stirred at 50 占 폚 for 20 hours. At the end of the stirring, the polyimide was completely dissolved. To this solution, 23.7 g of GBL, 73.2 g of NMP and 31.4 g of BCS were added and stirred at 50 DEG C for 20 hours to obtain a solid content (SPI-16) of 5.0 wt%, GBL of 47.4 wt%, NMP of 33.3 wt% A polyimide varnish having a BCS of 14.3 wt% was obtained. This polyimide varnish is directly used as a liquid crystal aligning agent for forming a liquid crystal alignment film. The agitation start time of the obtained polyimide varnish was evaluated according to the above-described evaluation method. The evaluation results are shown in Table 1.

(Example 16)

5.5 g of the polyimide (SPI-9) obtained in the same manner as in Example 7 and 5.5 g of the polyimide (SPI-15) obtained in the same manner as in Example 14 were mixed and 80.7 g of GBL was added and stirred at 50 DEG C for 20 hours . At the end of the stirring, the polyimide was completely dissolved. To this solution, 23.7 g of GBL, 73.2 g of NMP and 31.4 g of BCS were added and stirred at 50 DEG C for 20 hours to obtain a solid content (SPI-9 + SPI-15) of 5.0 wt%, GBL of 47.4 wt%, NMP of 33.3 wt%, and BCS of 14.3 wt%. This polyimide varnish is directly used as a liquid crystal aligning agent for forming a liquid crystal alignment film. The agitation start time of the obtained polyimide varnish was evaluated according to the above-described evaluation method. The evaluation results are shown in Table 1.

(Comparative Example 1)

80.7 g of GBL was added to 11.0 g of the polyimide (SPI-5) obtained in the same manner as in Example 5, and the mixture was stirred at 50 캜 for 20 hours. At the end of the stirring, the polyimide was completely dissolved. To this solution, 23.8 g of GBL, 41.8 g of NMP and 62.7 g of BCS were added and the mixture was stirred at 50 占 폚 for 20 hours to obtain 5.0 mass% of solid content (SPI-5), 47.5 mass% of GBL, 19.0 mass %, And a BCS of 28.5% by mass.

80.7 g of GBL was added to 11.0 g of the polyimide (SPI-6) obtained in the same manner as in Example 5, and the mixture was stirred at 50 占 폚 for 20 hours. At the end of the stirring, the polyimide was completely dissolved. To this solution, 23.8 g of GBL, 41.8 g of NMP and 62.7 g of BCS were added and stirred at 50 占 폚 for 20 hours to obtain 5.0 mass% of solids (SPI-6), 47.5 mass% of GBL, 19.0 mass %, And a BCS of 28.5% by mass.

Next, 140 g of the polyimide solution (SPI-5 concentration 5.0% by mass) obtained above and 60 g of polyimide solution (SPI-6 concentration 5.0% by mass) were mixed and stirred at room temperature for 2 hours, A polyimide varnish having 5.0 mass% of solid component (SPI-5 + SPI-6), 47.5 mass% of GBL, 19.0 mass% of NMP and 28.5 mass% of BCS was obtained. The agitation start time of the obtained polyimide varnish was evaluated according to the above-described evaluation method. The evaluation results are shown in Table 1.

(Comparative Example 2)

80.7 g of GBL was added to 11.0 g of the polyimide (SPI-7) obtained in the same manner as in Example 6, and the mixture was stirred at 50 DEG C for 20 hours. At the end of the stirring, the polyimide was completely dissolved. To this solution, 23.7 g of GBL, 73.2 g of NMP and 31.4 g of BCS were added and the mixture was stirred at 50 占 폚 for 20 hours to obtain 5.0 mass% of solids (SPI-7), 47.4 mass% of GBL, 33.3 mass %, And a BCS of 14.3 mass%.

80.7 g of GBL was added to 11.0 g of the polyimide (SPI-8) obtained in the same manner as in Example 6, and the mixture was stirred at 50 占 폚 for 20 hours. At the end of the stirring, the polyimide was completely dissolved. To this solution, 23.8 g of GBL, 41.8 g of NMP and 62.7 g of BCS were added and the mixture was stirred at 50 캜 for 20 hours to obtain 5.0 mass% of solids (SPI-8), 47.4 mass% of GBL, 33.3 mass %, And a BCS of 14.3 mass%.

Next, 140 g of the polyimide solution (SPI-7 concentration 5.0% by mass) obtained above and 60 g of a polyimide solution (SPI-8 concentration 5.0% by mass) were mixed and stirred at room temperature for 2 hours, 5.0% by mass of solid content (SPI-7 + SPI-8), 47.4% by mass of GBL, 33.3% by mass of NMP and 14.3% by mass of BCS. The agitation start time of the obtained polyimide varnish was evaluated according to the above-described evaluation method. The evaluation results are shown in Table 1.

(Comparative Example 3)

58.3 g of GBL was added to 7.0 g of the polyimide (SPI-9) obtained in the same manner as in Example 7, and the mixture was stirred at 50 占 폚 for 20 hours. At the end of the stirring, the polyimide was completely dissolved. To this solution, 8.2 g of GBL, 26.6 g of NMP and 39.9 g of BCS were added and stirred at 50 占 폚 for 20 hours to obtain a solid content (SPI-9) of 5.0 mass%, a GBL of 47.5 mass%, an NMP of 19.0 mass %, And a BCS of 28.5% by mass.

58.3 g of GBL was added to 7.0 g of the polyimide (SPI-5) obtained in the same manner as in Example 5, and the mixture was stirred at 50 占 폚 for 20 hours. At the end of the stirring, the polyimide was completely dissolved. To this solution, 8.2 g of GBL, 26.6 g of NMP and 39.9 g of BCS were added and stirred at 50 占 폚 for 20 hours to obtain a solid content (SPI-5) of 5.0 mass%, a GBL of 47.5 mass% and an NMP of 19.0 mass %, And a BCS of 28.5% by mass.

Next, 140 g of the polyimide solution (concentration of SPI-5 of 5.0% by mass) obtained above and 60 g of polyimide solution (concentration of SPI-9 of 5.0% by mass) were mixed and stirred at room temperature for 2 hours, 5.0% by mass of solid content (SPI-5 + SPI-9), 47.5% by mass of GBL, 19.0% by mass of NMP and 28.5% by mass of BCS. The agitation start time of the obtained polyimide varnish was evaluated according to the above-described evaluation method. The evaluation results are shown in Table 1.

(Comparative Example 4)

58.3 g of GBL was added to 7.0 g of the polyimide (SPI-10) obtained in the same manner as in Example 8, and the mixture was stirred at 50 DEG C for 20 hours. At the end of the stirring, the polyimide was completely dissolved. To this solution, 8.2 g of GBL, 26.6 g of NMP and 39.9 g of BCS were added and stirred at 50 占 폚 for 20 hours to obtain 5.0 mass% of solids (SPI-10), 47.5 mass% of GBL and 19.0 mass %, And a BCS of 28.5% by mass.

58.3 g of GBL was added to 7.0 g of the polyimide (SPI-5) obtained in the same manner as in Example 5, and the mixture was stirred at 50 DEG C for 20 hours. At the end of the stirring, the polyimide was completely dissolved. To this solution, 8.2 g of GBL, 26.6 g of NMP and 39.9 g of BCS were added and stirred at 50 占 폚 for 20 hours to obtain a solid content (SPI-5) of 5.0 mass%, a GBL of 47.5 mass% and an NMP of 19.0 mass %, And a BCS of 28.5% by mass.

Next, 140 g of the polyimide solution (concentration of SPI-5 of 5.0% by mass) obtained above and 60 g of polyimide solution (concentration of SPI-10 of 5.0% by mass) were mixed and stirred at room temperature for 2 hours, 5.0% by mass of solid content (SPI-5 + SPI-10), 47.5% by mass of GBL, 19.0% by mass of NMP and 28.5% by mass of BCS. The agitation start time of the obtained polyimide varnish was evaluated according to the above-described evaluation method. The evaluation results are shown in Table 1.

(Comparative Example 5)

80.7 g of GBL was added to 11.0 g of the polyimide (SPI-5) obtained in the same manner as in Example 5, and the mixture was stirred at 50 캜 for 20 hours. At the end of the stirring, the polyimide was completely dissolved. To this solution, 23.7 g of GBL, 73.2 g of NMP and 31.4 g of BCS were added and the mixture was stirred at 50 ° C for 20 hours to obtain a solid content (SPI-5) of 5.0 wt%, GBL of 47.4 wt%, NMP of 33.3 wt% A polyimide solution with BCS of 14.3 wt% was obtained.

80.7 g of GBL was added to 11.0 g of the polyimide (SPI-12) obtained in the same manner as in Example 10, and the mixture was stirred at 50 占 폚 for 20 hours. At the end of the stirring, the polyimide was completely dissolved. To this solution, 23.8 g of GBL, 41.8 g of NMP and 62.7 g of BCS were added and stirred at 50 DEG C for 20 hours to obtain a solid content (SPI-12) of 5.0 wt%, GBL of 47.4 wt%, NMP of 33.3 wt% A polyimide solution with BCS of 14.3 wt% was obtained.

Next, 160 g of the polyimide solution (SPI-5 concentration 5.0 wt%) and 40 g of the polyimide solution (SPI-12 concentration 5.0 wt%) were mixed and stirred at room temperature for 2 hours to obtain a solid (SPI- 12) 5.0 wt%, GBL 47.4 wt%, NMP 33.3 wt%, and BCS 14.3 wt%. Polyimide varnish was obtained. The agitation start time of the obtained polyimide varnish was evaluated according to the above-described evaluation method. The evaluation results are shown in Table 2.

(Comparative Example 6)

80.7 g of GBL was added to 11.0 g of the polyimide (SPI-8) obtained in the same manner as in Example 6, and the mixture was stirred at 50 占 폚 for 20 hours. At the end of the stirring, the polyimide was completely dissolved. To this solution, 23.7 g of GBL, 73.2 g of NMP and 31.4 g of BCS were added and stirred at 50 DEG C for 20 hours to obtain a solid content (SPI-8) of 5.0 wt%, GBL of 47.4 wt%, NMP of 33.3 wt% A polyimide solution with BCS of 14.3 wt% was obtained.

80.7 g of GBL was added to 11.0 g of the polyimide (SPI-10) obtained in the same manner as in Example 8, and the mixture was stirred at 50 캜 for 20 hours. At the end of the stirring, the polyimide was completely dissolved. To this solution, 23.8 g of GBL, 41.8 g of NMP and 62.7 g of BCS were added and stirred at 50 DEG C for 20 hours to obtain a solid content (SPI-10) of 5.0 wt%, GBL of 47.4 wt%, NMP of 33.3 wt% A polyimide solution with BCS of 14.3 wt% was obtained.

Next, 100 g of a polyimide solution (SPI-8 concentration 5.0 wt%) and 100 g of a polyimide solution (SPI-10 concentration 5.0 wt%) were mixed and stirred at room temperature for 2 hours to obtain a solid component (SPI- 10) 5.0 wt%, GBL 47.4 wt%, NMP 33.3 wt%, and BCS 14.3 wt%. Polyimide varnish was obtained. The agitation start time of the obtained polyimide varnish was evaluated according to the above-described evaluation method. The evaluation results are shown in Table 2.

(Comparative Example 7)

80.7 g of GBL was added to 11.0 g of the polyimide (SPI-6) obtained in the same manner as in Example 5, and the mixture was stirred at 50 占 폚 for 20 hours. At the end of the stirring, the polyimide was completely dissolved. To this solution, 23.7 g of GBL, 73.2 g of NMP and 31.4 g of BCS were added and stirred at 50 DEG C for 20 hours to obtain a solid content (SPI-6) of 5.0 wt%, GBL of 47.4 wt%, NMP of 33.3 wt% A polyimide solution with BCS of 14.3 wt% was obtained.

80.7 g of GBL was added to 11.0 g of the polyimide (SPI-15) obtained in the same manner as in Example 14, and the mixture was stirred at 50 占 폚 for 20 hours. At the end of the stirring, the polyimide was completely dissolved. To this solution, 23.8 g of GBL, 41.8 g of NMP and 62.7 g of BCS were added and stirred at 50 DEG C for 20 hours to obtain a solid content (SPI-15) of 5.0 wt%, GBL of 47.4 wt%, NMP of 33.3 wt% A polyimide solution with BCS of 14.3 wt% was obtained.

Next, 100 g of a polyimide solution (SPI-6 concentration 5.0 wt%) and 100 g of a polyimide solution (SPI-15 concentration 5.0 wt%) were mixed and stirred at room temperature for 2 hours to obtain a solid component (SPI- 15) 5.0 wt%, GBL 47.4 wt%, NMP 33.3 wt%, and BCS 14.3 wt%. Polyimide varnish was obtained. The agitation start time of the obtained polyimide varnish was evaluated according to the above-described evaluation method. The evaluation results are shown in Table 2.

(Comparative Example 8)

80.7 g of GBL was added to 11.0 g of the polyimide (SPI-9) obtained in the same manner as in Example 7, and the mixture was stirred at 50 占 폚 for 20 hours. At the end of the stirring, the polyimide was completely dissolved. To this solution, 23.7 g of GBL, 73.2 g of NMP and 31.4 g of BCS were added and stirred at 50 ° C for 20 hours to obtain a solid content (SPI-9) of 5.0 wt%, GBL of 47.4 wt%, NMP of 33.3 wt% A polyimide solution with BCS of 14.3 wt% was obtained.

80.7 g of GBL was added to 11.0 g of the polyimide (SPI-15) obtained in the same manner as in Example 14, and the mixture was stirred at 50 占 폚 for 20 hours. At the end of the stirring, the polyimide was completely dissolved. To this solution, 23.8 g of GBL, 41.8 g of NMP and 62.7 g of BCS were added and stirred at 50 DEG C for 20 hours to obtain a solid content (SPI-15) of 5.0 wt%, GBL of 47.4 wt%, NMP of 33.3 wt% A polyimide solution with BCS of 14.3 wt% was obtained.

Next, 100 g of a polyimide solution (SPI-9 concentration 5.0 wt%) and 100 g of a polyimide solution (SPI-15 concentration 5.0 wt%) were mixed and stirred at room temperature for 2 hours to obtain a solid component (SPI- 15) 5.0 wt%, GBL 47.4 wt%, NMP 33.3 wt%, and BCS 14.3 wt%. Polyimide varnish was obtained. The agitation start time of the obtained polyimide varnish was evaluated according to the above-described evaluation method. The evaluation results are shown in Table 2.

In Examples 1 to 4, 9, 11, 13, and 15, two types of polyimide precursor solutions were mixed to obtain a reaction solution The polyimide varnish is imidized as it is and a polyimide solution obtained by dissolving the two kinds of polyimide in a solvent is obtained to prepare a polyimide varnish. The varnish preparation methods of Examples 1 to 4, 9, 11, 13 and 15 are described as "I" in Table 1.

In Examples 5 to 8, 10, 12, 14 and 16, two types of powdery polyimides were separately prepared, mixed and dissolved in a solvent, and two types of polyimides were dissolved in a solvent To obtain a polyimide solution to prepare a polyimide varnish. The varnish preparation methods of Examples 5 to 8, 10, 12, 14 and 16 are described as "II" in Table 1.

In Comparative Examples 1 to 8, two kinds of powdery polyimides were prepared separately, and each of them was dissolved in a solvent to obtain two types of polyimide solutions. Thereafter, the respective polyimide solutions were mixed, A polyimide solution obtained by dissolving polyimide in a solvent is obtained to prepare a polyimide varnish. The varnish preparation methods of Comparative Examples 1 to 8 are described in Table 1 as &quot; III &quot;.

In addition, in the columns of the components shown in Tables 1 and 2, the polyamic acid solutions (PAA-1 to PAA-7) used in Examples and Comparative Examples were described as main components.

As shown in Table 1, the polyimide varnishes of Examples 1 to 4, 9, 11, 13 and 15 were the same as those of the polyamic acid solutions (PAA-1 to PAA-7) 1 to 8, it was found that the coagulation start time was long and the occurrence of coagulation at the time of formation of the coating film was hard to occur.

Likewise, the polyimide varnishes of Examples 5 to 8, 10, 12, 14 and 16 were the same as those of Comparative Examples 1 to 8 in which the polyamic acid solutions (PAA-1 to PAA-7) , It was found that the aggregation start time was long and the occurrence of aggregates at the time of forming the coating film was hard to occur.

From the above, it was found that the polyimide varnishes of Examples 1 to 16 can provide a liquid crystal aligning agent hard to cause aggregation at the time of forming the coating film.

It was also found that the liquid crystal aligning agents using the polyimide varnishes of Examples 1 to 4 were particularly preferable for suppressing the generation of agglomerates at the time of formation of the coating film.

Industrial availability

The polyimide varnish obtained by the method for preparing a polyimide varnish of the present invention is preferably used as a liquid crystal aligning agent having a feature of being excellent in printing property and hardly forming an aggregate at the time of forming a coating film.

The liquid crystal display device having a liquid crystal alignment film formed using the liquid crystal aligning agent of the present invention is excellent in uniformity of display and has a high display quality and can be used as a liquid crystal TV of a large size or a smart phone displaying a high- It can be preferably used as a display device for a portable information terminal.

The entire contents of the specification, claims and abstract of Japanese Patent Application No. 2012-014416 filed on January 26, 2012 are hereby incorporated herein by reference and the disclosure of the specification of the present invention is hereby incorporated by reference.

Claims (14)

A method for preparing a liquid crystal aligning agent using a polyimide varnish obtained by dissolving two or more kinds of polyimides obtained by imidizing each of the polyimide precursors in a solution containing two or more kinds of polyimide precursors. The method according to claim 1,
Wherein the concentration of the polyimide precursor in the solution is 1 to 12 mass%. The method according to claim 1,
Wherein the imidization of the polyimide precursor in the solution is carried out after 10 to 12 hours have elapsed after preparing a solution containing the two or more kinds of polyimide precursors. The method according to claim 1,
Wherein at least one of the two or more kinds of polyimide precursors is 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride, 3,4-dicarboxy-1,2,3,4-tetrahydro-1- Wherein the liquid crystal aligning agent is a polyimide precursor formed by using at least one selected from the group consisting of naphthalene succinic dianhydride and aromatic tetracarboxylic acid dianhydride containing an aromatic ring. A method for preparing a polyimide varnish comprising mixing two or more kinds of polyimides in a powder state, dissolving the mixed polyimide powder in a solvent, and dissolving two or more kinds of polyimides. 6. The method of claim 5,
Wherein at least one of the two or more kinds of polyimides is at least one selected from the group consisting of 1,2,3,4-cyclobutane tetracarboxylic acid dianhydride, 3,4-dicarboxy-1,2,3,4-tetrahydro-1-naphthalene Wherein the polyimide precursor is formed by imidizing a polyimide precursor formed by using at least one member selected from the group consisting of succinic acid dianhydride and aromatic tetracarboxylic acid dianhydride containing an aromatic ring. 5. The method according to any one of claims 1 to 4,
Wherein the polyimide has a weight average molecular weight of 10,000 to 15,000. A liquid crystal aligning agent obtained by the method for preparing a liquid crystal aligning agent according to any one of claims 1 to 4. The method according to claim 5 or 6,
Wherein the polyimide has a weight average molecular weight of 10000 to 150000. A polyimide varnish obtained by using the method for preparing polyimide varnish according to claim 5 or 6. 9. The method of claim 8,
Further, a liquid crystal aligning agent containing at least one selected from the group consisting of N-methyl-2-pyrrolidone and? -Butyrolactone. A liquid crystal alignment film obtained from the liquid crystal alignment agent according to claim 8. 13. The method of claim 12,
A liquid crystal alignment film having a film thickness of 10 to 200 m. A liquid crystal display element comprising the liquid crystal alignment film according to claim 12.