WO2013111836A1 - Method for preparing polyimide varnish, and liquid crystal aligning agent - Google Patents

Abstract

Provided are: a method for preparing a polyimide varnish, wherein a polyimide varnish which contains a polyimide dissolved therein and has excellent printability by suppressing generation of agglomerates; and a liquid crystal aligning agent which uses the thus-obtained polyimide varnish. A method wherein two or more kinds of polyimide precursors are respectively imidized in a solution that contains the polyimide precursors, thereby preparing a polyimide varnish which contains two or more kinds of polyimides dissolved therein; or alternatively, a method wherein two or more kinds of polyimides are mixed in a powder form and the thus-obtained polyimide powder, in which two or more kinds of polyimides are mixed, is dissolved in a solvent, thereby preparing a polyimide varnish.

Description

Preparation method of polyimide varnish and liquid crystal aligning agent

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 has been widely used as an interlayer insulating film, a protective film, and the like in electronic devices because of its ease of formation and insulation performance. Polyimide is known as an organic material frequently used in such electronic devices.

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. The liquid crystal display element has a structure in which liquid crystal molecules are sandwiched between liquid crystal alignment films formed on the surfaces of a pair of substrates. The display element utilizes the fact that liquid crystal molecules aligned in a certain direction with a pretilt angle by the liquid crystal alignment film respond by a voltage applied to an electrode provided between the substrate and the liquid crystal alignment film.

This liquid crystal alignment film is generally produced by performing a so-called “rubbing process” in which the surface of a polyimide film formed on a substrate with electrodes is rubbed against the surface with rayon or nylon cloth. Yes.
In addition, a liquid crystal alignment film for VA (Vertical Alignment: vertical alignment) that does not undergo rubbing treatment, and a photo alignment film that imparts anisotropy to the film surface by irradiating polarized UV and aligns the liquid crystal have attracted attention.

As a method of forming a polyimide film to be a liquid crystal alignment film on a substrate with electrodes, using a liquid crystal alignment agent using a varnish prepared containing a polyimide precursor such as polyamic acid (also referred to as polyamic acid), A method of producing the coating film and imidizing on the substrate is known.
As another method, there is a method in which a polyimide that has been imidized in advance is dissolved in a solvent to prepare a so-called solvent-soluble polyimide varnish, and a polyimide film is formed using a liquid crystal aligning agent using the polyimide varnish. is there.

Among these, the method of using a liquid crystal aligning agent using a solvent-soluble polyimide varnish can form a polyimide film having good characteristics when used as a liquid crystal aligning film even when firing at a relatively low temperature. It has the characteristics. However, since polyimide is generally inferior in solubility in organic solvents compared to polyamic acid, etc., when imidized in advance, printability on the substrate is reduced, and a uniform coating film is formed. May be difficult. Furthermore, it may become insoluble in the conventional solvent used for varnish, and it may become impossible to make a liquid crystal aligning agent contain a polyimide.

As a method for solving such a problem, a method of obtaining a liquid crystal aligning agent by blending a polyimide precursor with a varnish prepared by dissolving polyimide in a solvent has been proposed (for example, see Patent Document 1).
In addition, a method of obtaining a liquid crystal aligning agent by blending polyimides having different imidization ratios (see, for example, 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 aligning film. However, the conventional liquid crystal aligning agent using phase separation is liable to cause a problem of whitening due to moisture absorption and precipitation of aggregates during printing on a substrate for forming a coating film. Furthermore, the phase separation property changes depending on the baking conditions after being applied to the substrate, and the alignment film characteristics such as the pretilt angle formation characteristics and voltage holding characteristics (also referred to as VHR) required for the liquid crystal alignment film are obtained. There was also a problem that changed.

For such changes in alignment film properties, it is effective to prepare a varnish using polyimide having a high imidization rate and prepare a liquid crystal aligning agent using the varnish. 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, even in such a liquid crystal aligning agent, agglomerates may be generated within a short time by drying during printing for forming a coating film on the substrate.
Furthermore, in a liquid crystal display element using a liquid crystal alignment film, there is a problem that gap unevenness occurs between substrates that sandwich liquid crystal molecules.
In addition, a liquid crystal aligning agent containing a soluble polyimide using a high-boiling polar solvent has been proposed so as to improve the above-described problems of printability and aggregate formation (see, for example, Patent Document 5). However, the effect of improvement is not sufficient with respect to the agglomerates generated during coating and drying on the substrate.

Japanese Unexamined Patent Publication No. 08-220541 Japanese Unexamined Patent Publication No. 09-297312 Japanese Unexamined Patent Publication No. 09-311338 International Publication No. 2008/62877 Pamphlet International Publication No. 2009/148100 Pamphlet

As described above, there is a need for a technique that can suppress the generation of aggregates due to moisture absorption and provide a polyimide varnish excellent in printability. And the liquid crystal aligning agent which is prepared from a polyimide varnish, suppresses generation | occurrence | production of an aggregate, is excellent in printability, and can form a liquid crystal aligning film is calculated | required.

This invention is made | formed in view of the above situations, and the objective of this invention is suppressing the generation | occurrence | production of the aggregate and providing the preparation method of the polyimide varnish excellent in printability.
Moreover, the objective of this invention is providing the liquid crystal aligning agent excellent in printability by which generation | occurrence | production of the aggregate was suppressed using the polyimide varnish obtained using the said preparation method.

The present invention has the following gist.
(1) A method for preparing a polyimide varnish comprising imidizing each of the polyimide precursors in a solution containing two or more types of polyimide precursors, and dissolving and containing two or more types of polyimides.

(2) The method for preparing a polyimide varnish according to the above (1), wherein the concentration of the polyimide precursor in the solution is 1 to 12% by mass.
(3) The imidation of the polyimide precursor in the solution is carried out after 10 minutes to 12 hours have elapsed after preparing a solution containing the two or more types of polyimide precursors. The method for preparing a polyimide varnish as described in 2).

(4) At least one of the two or more types of polyimide precursors is 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 3,4-dicarboxy-1,2,3,4-tetrahydro (1) to (1) are polyimide precursors formed using at least one selected from the group consisting of -1-naphthalene succinic dianhydride and an aromatic tetracarboxylic dianhydride containing an aromatic ring. The method for preparing a polyimide varnish according to any one of 3).

(5) A method for preparing a polyimide varnish comprising mixing two or more types of polyimide in a powder state, dissolving the obtained polyimide powder in a solvent, and dissolving and containing two or more types of polyimide.

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

(7) The method for preparing a polyimide varnish according to any one of the above (1) to (6), wherein the polyimide has a weight average molecular weight of 10,000 to 150,000.

(8) A polyimide varnish obtained using the method for preparing a polyimide varnish according to any one of (1) to (4) above.
(9) A polyimide varnish obtained using the method for preparing a polyimide varnish according to any one of (5) to (7) above.

(10) A liquid crystal aligning agent obtained using the polyimide varnish described in (8) or (9) above.
(11) The liquid crystal aligning agent according to the above (10), further comprising at least one selected from the group consisting of N-methyl-2-pyrrolidone and γ-butyrolactone.

(12) A liquid crystal alignment film obtained from the liquid crystal aligning agent according to any of (10) or (11).
(13) The liquid crystal alignment film according to (12), wherein the film thickness is 10 to 200 μm.

(14) A liquid crystal display device 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 that dissolves and contains polyimide, suppresses the generation of aggregates, has excellent printability, and facilitates uniform coating film formation.

Furthermore, by using the polyimide varnish obtained by the present invention, it is possible to provide a liquid crystal aligning agent that contains polyimide, suppresses the generation of aggregates, has excellent printability, and facilitates uniform film formation. .

As a result of intensive studies, the present inventors have obtained the following knowledge and completed the present invention.
That is, as disclosed in Patent Document 2 and Patent Document 3, conventionally, a liquid crystal aligning agent containing two or more types of polyimide is known, but a conventional polyimide varnish containing two or more types of polyimide is Separately prepare solutions containing two or more kinds of polyimide precursors, perform imidization separately in each solution, and then perform polyimide recovery and purification of the polyimide for each of the obtained polyimide solutions. . And each obtained polyimide is dissolved in a solvent, and two or more types of polyimide solutions corresponding to the number of types of polyimide are obtained. Subsequently, each polyimide solution is mixed and the polyimide varnish containing 2 or more types of polyimide is prepared. In the polyimide varnish thus obtained, as shown in a comparative example to be described later, agglomerates are generated within a relatively short time. Therefore, in the liquid crystal aligning agent using such a polyimide varnish, similarly, Aggregates are generated within a relatively short time after the coating is formed.

The inventors of the present invention have made researches to solve the above-mentioned difficulties of the conventional polyimide varnish containing two or more kinds of polyimides, and in the solution containing two or more kinds of polyimide precursors, the polyimide precursors. A method for preparing a polyimide varnish containing two or more types of polyimide by mixing each body simultaneously with imidization, or mixing two or more types of polyimide in a powdered state, and mixing the two or more types of polyimide obtained. It has been found that the above-mentioned problems can be solved by a method in which the prepared polyimide powder is simultaneously dissolved in a solvent.

Although it is not always clear why the problem can be solved by the method of preparing such a polyimide varnish, it is considered as follows. That is, in the method of imidizing two types of polyimide precursors simultaneously in a solution containing two or more types of polyimide precursors, the polyimide precursors contained in each other are in a solution containing two or more types of polyimide precursors. As a result, amide exchange, etc. by some polyimide precursors occurs, so that compatibility is improved. As a result, the obtained polyimide varnish is considered to be excellent in printability and suppress the formation of aggregates. It is done.

The same applies to a method in which two or more types of polyimide are mixed in a powder state, and the obtained polyimide powder in which two or more types of polyimide are mixed is simultaneously dissolved in a solvent. There is an unconverted polyimide precursor that is determined by the imidization rate, but such polyimide precursors interact with each other, and amide exchange by a part of the polyimide precursor occurs, thereby improving compatibility. Conceivable. *

[Polyimide varnish and its preparation method]
In the present invention, the two or more kinds of polyimides mean those having different structures of polyimide precursors as corresponding raw materials. That is, the raw material of the polyimide precursor, which is different from the type of tetracarboxylic acid dihydrate and diamine, and those composed of the same tetracarboxylic acid dihydrate and diamine combination, each having a different ratio It becomes another kind of polyimide precursor.
In the present invention, the polyimide precursor is a polyamic acid and / or a polyamic acid ester. In the present invention, a particularly preferred 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 depending on circumstances, three or more kinds or even four or more kinds may be used. .

In the method for preparing a polyimide varnish of the present invention, first, a solution containing two or more types of polyimide precursors corresponding to each of two or more types of polyimide to be contained is prepared. Each polyimide precursor contained in the solution is formed from a different combination of tetracarboxylic dianhydride or its derivative and diamine, and has a different structure.

Using this solution as a reaction solution, the polyimide precursor contained therein is imidized using the solution. As a result, a polyimide solution containing two or more types of polyimide is obtained. This polyimide solution can be used as it is as the polyimide varnish of the present invention. Preferably, after the polyimide is recovered and the polyimide is purified from the obtained polyimide solution, the polyimide varnish of the present invention can be prepared by dissolving two or more types of polyimide in a solvent again. it can.

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

In forming a polyimide precursor to be converted to polyimide, the raw material tetracarboxylic dianhydride or its derivative and diamine may be appropriately selected according to the polyimide varnish containing two or more types of polyimide to be produced. it can.
As a method for preparing a solution containing two or more kinds of polyimide precursors, for two or more kinds of polyimides to be contained in a polyimide varnish, a solution containing a polyimide precursor corresponding to each is separately prepared, and the solutions are mixed with each other. Is possible.

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

An example of the method for preparing the polyimide varnish of the present invention will be described more specifically below.
In the method for preparing a polyimide varnish of the present invention, first, a tetracarboxylic dianhydride having a desired structure or a derivative thereof is selected, and a diamine having a desired structure is selected correspondingly. Next, they are reacted with each other in an appropriate solvent and polymerized to obtain a polyimide precursor such as polyamic acid having a desired structure in a solution state. Similarly, a plurality of types of solutions containing polyimide precursors having different structures are obtained.

In addition, after obtaining the polyimide precursor in a solution state, the polyimide precursor is recovered from the solution, and after necessary purification and the like, the recovered polyimide precursor may be used for the preparation of the polyimide varnish. Is possible. For example, the polyimide precursor can be dissolved again in a desired solvent, and the resulting polyimide precursor solution can be used to prepare a polyimide varnish.
In obtaining a polyimide precursor such as polyamic acid, it is preferable to use tetracarboxylic dianhydride as the tetracarboxylic dianhydride having a desired structure or a derivative thereof.

In the method for preparing a polyimide varnish of the present invention, tetracarboxylic dianhydrides and diamines that can be selected and diamine will be specifically described below.

<Tetracarboxylic dianhydride and its derivative>
In order to obtain the polyamic acid used in the method for preparing the polyimide varnish of the present invention, the tetracarboxylic dianhydride to be reacted with the diamine is not particularly limited. Specific examples are given below.

Examples of the tetracarboxylic dianhydride having an alicyclic structure or an aliphatic structure include 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2-dimethyl-1,2,3,4-cyclobutane. Tetracarboxylic dianhydride, 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-tetramethyl-1,2,3,4-cyclobutanetetra Carboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 2,3,4,5-tetrahydrofurantetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic Acid dianhydride, 3,4-dicarboxy-1-cyclohexylsuccinic dianhydride, 3,4-dicarboxy-1,2,3,4-tetrahydro-1-naphthalene succinic dianhydride, 1, , 3,4-Butanetetracarboxylic dianhydride, bicyclo [3,3,0] octane-2,4,6,8-tetracarboxylic dianhydride, 3,3 ′, 4,4′-dicyclohexyltetra Carboxylic dianhydride, 2,3,5-tricarboxycyclopentyl acetic acid dianhydride, cis-3,7-dibutylcycloocta-1,5-diene-1,2,5,6-tetracarboxylic dianhydride , Tricyclo [4.2.1.0 ^2,5 ] nonane-3,4,7,8-tetracarboxylic acid-3,4: 7,8-dianhydride, hexacyclo [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-dianhydride, 4- (2,5-di-oxo-tetrahydrofuran-3-yl) -1,2 3,4-tetrahydronaphthalene-1,2-dicarboxylic anhydride and the like.

Aromatic tetracarboxylic dianhydrides can also be used. An aromatic tetracarboxylic dianhydride is a tetracarboxylic dianhydride containing an aromatic ring.
The aromatic tetracarboxylic dianhydride can be used in addition to the tetracarboxylic dianhydride having the alicyclic structure or the aliphatic structure. If aromatic tetracarboxylic dianhydride is used in this way, the liquid crystal alignment film formed from the liquid crystal aligning agent using the resulting polyimide varnish will improve the liquid crystal alignment and reduce the accumulated charge of the liquid crystal display element. Can be made.

Examples of aromatic tetracarboxylic dianhydrides that can be used include pyromellitic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, and 2,2 ′, 3,3′-biphenyl. Tetracarboxylic dianhydride, 2,3,3 ′, 4′-biphenyltetracarboxylic dianhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, 2,3,3 ′, 4'-benzophenonetetracarboxylic dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, bis (3,4-dicarboxyphenyl) sulfone dianhydride, 1,2,5,6-naphthalene Examples thereof include tetracarboxylic dianhydride and 2,3,6,7-naphthalenetetracarboxylic dianhydride.

Among them, tetracarboxylic dianhydrides are 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA), 3,4-dicarboxy-1,2,3,4-tetrahydro-1-naphthalene. Use of succinic dianhydride (TDA), pyromellitic dianhydride (PMDA), 2,3,5-tricarboxycyclopentylacetic acid dianhydride (TCA) or the like is preferable. The polyamic acid obtained by using these is converted into polyimide, and is particularly suitable for realizing a polyimide varnish that has excellent printability and suppresses the formation of aggregates when a coating film is formed on the substrate. These tetracarboxylic dianhydrides are understood to be suitable for the interaction between the polyimide precursors described above, in particular, amide exchange, and are considered to exhibit effects such as improved printability.

Tetracarboxylic dianhydride is a liquid crystal alignment film formed from a liquid crystal aligning agent that uses the polyimide varnish obtained while considering the printability of the resulting polyimide varnish and the effect of suppressing the formation of aggregates during coating formation. In order to form one polyimide precursor according to characteristics such as liquid crystal orientation, voltage holding characteristics, and accumulated charge, one kind or two or more kinds can be used in combination.

When two or more kinds of tetracarboxylic dianhydrides are used in combination to form a single polyimide precursor, the above-described 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA), 3, 4-dicarboxy-1,2,3,4-tetrahydro-1-naphthalene succinic dianhydride (TDA), pyromellitic dianhydride (PMDA), 2,3,5-tricarboxycyclopentyl acetate dianhydride The use ratio of one kind of tetracarboxylic dianhydrides such as (TCA) is preferably 10 mol% or more of the total tetracarboxylic dianhydrides. More preferably, it is 30 mol% or more of the whole tetracarboxylic dianhydride. Among these, 60 to 100 mol% is particularly preferable.

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

Specific examples of the aliphatic tetracarboxylic acid diester include 1,2,3,4-cyclobutanetetracarboxylic acid dialkyl ester, 1,2-dimethyl-1,2,3,4-cyclobutanetetracarboxylic 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-tetrahydrofurantetracarboxylic acid dialkyl ester, 1,2,4,5-cyclohexanetetracarboxylic acid dialkyl ester, 3,4-dicarboxy- 1-cyclohexyl succinic acid dialkyl ester, 3,4-dicarboxy 1,2,3,4-tetrahydro-1-naphthalene succinic 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 dialkyl ester, 2,3,5-tricarboxycyclopentylacetic 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-dialkyl ester, hexacyclo [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-dialkyl ester, 4- (2,5-di-oxo-tetrahydrofuran-3-yl) -1,2, Examples include 3,4-tetrahydronaphthalene-1,2-dicarboxylic dialkyl 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′-biphenyltetracarboxylic acid dialkyl ester, 2,3,3 ′, 4′-biphenyltetracarboxylic acid dialkyl ester, 3,3 ′, 4,4′-benzophenone tetracarboxylic acid dialkyl ester, 2,3,3 ′, 4′-benzophenone tetracarboxylic acid dialkyl ester Bis (3,4-dicarboxyphenyl) ether dialkyl ester, bis (3,4-dicarboxyphenyl) sulfone dialkyl ester, 1,2,5,6-naphthalenetetracarboxylic acid dialkyl ester, 2,3,6, Dialkyl 7-naphthalenetetracarboxylate Ester, and the like.

<Diamine>
When obtaining the polyimide precursor used with the preparation method of the polyimide varnish of this invention, the diamine which can be used for reaction with tetracarboxylic dianhydride etc. is not specifically limited. Selection is preferably made to correspond to the desired polyimide precursor structure. Specific examples of diamines that can be selected are as follows.

Examples of alicyclic diamines include 1,4-diaminocyclohexane, 1,3-diaminocyclohexane, 4,4′-diaminodicyclohexylmethane, 4,4′-diamino-3,3′-dimethyldicyclohexylamine, isophorone diamine Etc.

Examples of aromatic diamines include o-phenylene diamine, m-phenylene diamine, p-phenylene diamine, 2,4-diaminotoluene, 2,5-diaminotoluene, 3,5-diaminotoluene, 1,4-diamino- 2-methoxybenzene, 2,5-diamino-p-xylene, 1,3-diamino-4-chlorobenzene, 3,5-diaminobenzoic acid, 1,4-diamino-2,5-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'-diamy Stilbene, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, 4,4'- Diaminobenzophenone, 1,3-bis (3-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) benzene, 3,5-bis (4- Aminophenoxy) benzoic acid, 4,4'-bis (4-aminophenoxy) bibenzyl, 2,2-bis [(4-aminophenoxy) methyl] propane, 2,2-bis [4- (4-aminophenoxy) Phenyl] hexafluoropropane, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, [4- (3-aminophenoxy) phenyl] sulfone, bis [4- (4-aminophenoxy) phenyl] sulfone, 1,1-bis (4-aminophenyl) cyclohexane, α, α′-bis (4- Aminophenyl) -1,4-diisopropylbenzene, 9,9-bis (4-aminophenyl) fluorene, 2,2-bis (3-aminophenyl) hexafluoropropane, 2,2-bis (4-aminophenyl) Hexafluoropropane, 4,4'-diaminodiphenylamine, 2,4-diaminodiphenylamine, 1,8-diaminonaphthalene, 1,5-diaminonaphthalene, 1,5-diaminoanthraquinone, 1,3-diaminopyrene, 1,6 -Diaminopyrene, 1,8-diaminopyrene, 2,7-diaminofluorene, 1,3-bis (4-amino Enyl) tetramethyldisiloxane, benzidine, 2,2′-dimethylbenzidine, 1,2-bis (4-aminophenyl) ethane, 1,3-bis (4-aminophenyl) propane, 1,4-bis (4 -Aminophenyl) butane, 1,5-bis (4-aminophenyl) pentane, 1,6-bis (4-aminophenyl) hexane, 1,7-bis (4-aminophenyl) heptane, 1,8-bis (4-aminophenyl) octane, 1,9-bis (4-aminophenyl) nonane, 1,10-bis (4-aminophenyl) decane, 1,3-bis (4-aminophenoxy) propane, 1,4 -Bis (4-aminophenoxy) butane, 1,5-bis (4-aminophenoxy) pentane, 1,6-bis (4-aminophenoxy) hexane, 1,7-bis (4- Aminophenoxy) heptane, 1,8-bis (4-aminophenoxy) octane, 1,9-bis (4-aminophenoxy) nonane, 1,10-bis (4-aminophenoxy) decane, di (4-aminophenyl) ) Propane-1,3-dioate, di (4-aminophenyl) butane-1,4-dioate, di (4-aminophenyl) pentane-1,5-dioate, di (4-aminophenyl) hexane-1, 6-dioate, di (4-aminophenyl) heptane-1,7-dioate, di (4-aminophenyl) octane-1,8-dioate, di (4-aminophenyl) nonane-1,9-dioate, di (4-aminophenyl) decane-1,10-dioate, 1,3-bis [4- (4-aminophenoxy) phenoxy] propane, 1,4-bi [4- (4-aminophenoxy) phenoxy] butane, 1,5-bis [4- (4-aminophenoxy) phenoxy] pentane, 1,6-bis [4- (4-aminophenoxy) phenoxy] hexane, , 7-bis [4- (4-aminophenoxy) phenoxy] heptane, 1,8-bis [4- (4-aminophenoxy) phenoxy] octane, 1,9-bis [4- (4-aminophenoxy) phenoxy Nonane, 1,10-bis [4- (4-aminophenoxy) phenoxy] decane, and the like.

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

(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, and R ₂ represents a hydrogen atom or a methyl group.

Specific examples of the aromatic-aliphatic diamine include 3-aminobenzylamine, 4-aminobenzylamine, 3-amino-N-methylbenzylamine, 4-amino-N-methylbenzylamine, 3-aminophenethylamine, 4 -Aminophenethylamine, 3-amino-N-methylphenethylamine, 4-amino-N-methylphenethylamine, 3- (3-aminopropyl) aniline, 4- (3-aminopropyl) aniline, 3- (3-methylaminopropyl) ) Aniline, 4- (3-methylaminopropyl) aniline, 3- (4-aminobutyl) aniline, 4- (4-aminobutyl) aniline, 3- (4-methylaminobutyl) aniline, 4- (4- Methylaminobutyl) aniline, 3- (5-aminopentyl) aniline, 4- (5-aminopen) L) aniline, 3- (5-methylaminopentyl) aniline, 4- (5-methylaminopentyl) aniline, 2- (6-aminonaphthyl) methylamine, 3- (6-aminonaphthyl) methylamine, 2- (6-Aminonaphthyl) ethylamine, 3- (6-aminonaphthyl) ethylamine and the like can be mentioned.

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

Examples of aliphatic diamines include 1,2-diaminoethane, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, 1,10-diaminodecane, 1,3-diamino-2,2-dimethylpropane, 1,6-diamino-2,5-dimethylhexane, 1,7- Diamino-2,5-dimethylheptane, 1,7-diamino-4,4-dimethylheptane, 1,7-diamino-3-methylheptane, 1,9-diamino-5-methylnonane, 1,12-diaminododecane, Examples thereof include 1,18-diaminooctadecane and 1,2-bis (3-aminopropoxy) ethane.

Further, when obtaining a polyimide precursor such as polyamic acid, the diamine that can be selected has an alkyl group, a fluorine-containing alkyl group, an aromatic ring, an aliphatic ring, a heterocyclic ring, and a macrocyclic substituent composed of these in the side chain. A diamine compound may be used in combination. Specifically, diamines represented by the following formulas [DA-1] to [DA-40] can be exemplified.

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

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

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

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

(In formula [DA-15] and formula [DA-16], S ₈ represents —COO—, —OCO—, —CONH—, —NHCO—, —COOCH ₂ —, —CH ₂ OCO—, —CH ₂ O—, —OCH ₂ —, —CH ₂ —, —O—, or NH—, and R ₉ is fluorine, cyano, trifluoromethyl, nitro, azo, formyl, acetyl, acetoxy Group or hydroxyl group.)

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

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

(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] are liquid crystals that use a liquid crystal aligning film formed from a liquid crystal aligning agent that uses the polyimide varnish obtained by the polyimide varnish preparation method of the present invention. The voltage holding ratio (VHR) of the display element can be improved.
In addition, it is preferable to use the diamines [DA-33] to [DA-38] because they are effective in reducing the accumulated charge of the liquid crystal display element to be obtained. Furthermore, it is preferable to use [DA-39] or [DA-40] because it is effective in reducing the accumulated charge of the liquid crystal display element.

Furthermore, when obtaining a polyimide precursor such as polyamic acid, examples of a diamine that can be selected include diaminosiloxanes represented by the following formula [DA-41].

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

In obtaining the polyimide precursor, the diamine is a single polyimide precursor depending on the liquid crystal alignment properties of the liquid crystal alignment film formed from the liquid crystal aligning agent obtained using the polyimide varnish, voltage holding, accumulated charge and the like. In order to form a body, 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 synthesis method can be used to obtain a polyimide precursor by reaction of tetracarboxylic dianhydride and diamine. For example, it is possible to use a method in which tetracarboxylic dianhydride and diamine are reacted in an organic solvent. This method is preferable in that the reaction proceeds relatively efficiently in an organic solvent and generation of by-products is small.

The organic solvent used for the reaction of tetracarboxylic dianhydride and diamine is not particularly limited as long as the produced polyamic acid can be dissolved. Specific examples include N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methylcaprolactam, dimethylsulfoxide, tetramethylurea, pyridine, dimethylsulfone, hexamethylsulfoxide, γ- Butyrolactone, isopropyl alcohol, methoxymethylpentanol, dipentene, ethyl amyl ketone, methyl nonyl ketone, methyl ethyl ketone, methyl isoamyl ketone, methyl isopropyl ketone, methyl cellosolve, ethyl cellosolve, methyl cellosolve acetate, ethyl cellosolve acetate, butyl carbitol, Ethyl carbitol, ethylene glycol, ethylene glycol monoacetate, ethylene glycol monoisopropyl ether, ethylene glycol Nobutyl ether, propylene glycol, propylene 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, amyl acetate, butyl butyrate, butyl ether, diisobutyl ketone, methylcyclohexene, propyl ether, dihexyl ether, dioxane, n-hexane , N-pentane, n-octane, diethyl ether, cyclohexanone, ethylene carbonate, propylene carbonate, methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, n-butyl acetate, propylene glycol monoethyl ether, methyl pyruvate, pyruvic acid Ethyl, methyl 3-methoxypropionate, methyl ethyl 3-ethoxypropionate, ethyl 3-methoxypropionate, 3-ethoxypropionic acid, 3-metho Shipuropion acid, 3-methoxy propionic acid propyl, 3-methoxy propionic acid butyl, can be given diglyme or 4-hydroxy-4-methyl-2-pentanone and the like. These may be used alone or in combination. Moreover, even if it is a solvent which does not dissolve polyimide precursors, such as a polyamic acid, if it is the range which does not precipitate the produced | generated polyimide precursor, it can also be mixed and used for the said solvent.
In addition, since the water | moisture content in an organic solvent inhibits a polymerization reaction and causes the produced | generated polyimide precursor to hydrolyze, it is preferable to use what dehydrated and dried the organic solvent.

When reacting tetracarboxylic dianhydride and diamine in an organic solvent, the solution in which the diamine is dispersed or dissolved in the organic solvent is stirred, and the tetracarboxylic dianhydride is dispersed as it is or in the organic solvent. Alternatively, it is possible to use a method of dissolving and adding. Inversely, a method of adding diamine to a solution in which tetracarboxylic dianhydride is dispersed or dissolved in an organic solvent, a method of alternately adding tetracarboxylic dianhydride and diamine, and the like can also be mentioned. . Any of these methods may be used in the present invention. Moreover, when tetracarboxylic dianhydride and / or diamine are composed of a plurality of types of compounds, they may be reacted in a premixed state, may be individually reacted sequentially, or may be further reacted individually. The body may be mixed and reacted to form a high molecular weight body.

The temperature for reacting the tetracarboxylic dianhydride and the diamine can be arbitrarily selected within the range of −20 to 150 ° C., but in the range of −5 to 100 ° C. in consideration of the reaction efficiency. Is preferred. Moreover, reaction can be performed by arbitrary density | concentrations. However, if the concentration is too low, it is difficult to obtain a high molecular weight polyimide precursor. On the other hand, if the concentration is too high, the viscosity of the reaction solution becomes too high and uniform stirring becomes difficult. Therefore, it is preferably 1 to 50% by mass, more preferably 5 to 30% by mass. It is also possible to carry out the reaction at a high concentration at the beginning of the reaction and then add an organic solvent.

When the tetracarboxylic dianhydride and the diamine are reacted, the ratio of the number of moles of the tetracarboxylic dianhydride and the diamine is preferably 0.8 to 1.2. Similar to the normal polycondensation reaction, the closer the molar ratio is to 1, the higher the degree of polymerization of the polymer produced. When the degree of polymerization is too small, the strength of the polyimide coating film by the formed polyimide varnish is insufficient, and when the degree of polymerization is too large, workability at the time of forming the polyimide coating film may be deteriorated.

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

When the concentration of the polyimide precursor in the reaction solution is lower than 1% by mass, the interaction between the polyimide precursors becomes weak, and in the resulting polyimide varnish, sufficient printability improvement effect and aggregates at the time of coating film formation The characteristic that it is difficult to form is not fully realized, and the filterability at the time of recovery of the powdered polyimide obtained on the way is deteriorated. Moreover, when the density | concentration of the polyimide precursor in a reaction solution is higher than 12 mass%, when collect | recovering the polyimide obtained by imidation, the efficiency of refinement | purification will fall. The concentration of the polyimide precursor in the reaction solution is more preferably 3 to 10% by mass, and further preferably 5 to 8% by mass.

In the method for preparing a polyimide varnish of the present invention, the reaction solution obtained as described above is allowed to elapse for 10 minutes to 12 hours before imidizing each polyimide precursor in the reaction solution, as described later. Is preferred. When the elapsed time from the reaction solution to imidization is shorter than 10 minutes, the resulting polyimide varnish sufficiently realizes the effect of improving the printability and that it is difficult to form agglomerates during coating formation. Not. Moreover, when elapsed time exceeds 12 hours, preparation of a polyimide varnish will take time too much, and the productivity of a polyimide varnish will fall. The elapsed time until imidization after obtaining the reaction solution is more preferably 30 minutes to 6 hours, and further preferably 1 to 5 hours. Moreover, after obtaining the reaction solution, it is preferable that the reaction solution is stirred until imidization is performed. Moreover, when it is going to shorten the elapsed time until imidation after obtaining the reaction solution, it is preferable to raise the temperature of the reaction solution from room temperature, for example, in a range in which imidization does not proceed.

Next, in the method for preparing a polyimide varnish of the present invention, each polyimide precursor in the above reaction solution was imidized, each was converted to a polyimide, and two or more kinds of polyimides derived from each polyimide precursor were contained. A polyimide solution is obtained. This polyimide solution is a state in which two or more kinds of polyimides are dissolved in a solvent, and can be used as it is as the polyimide varnish of the present invention.
At this time, the imidization rate (dehydration ring closure rate) of each polyimide precursor is not necessarily 100%, and is preferably 40 to 90%, more preferably 45 to 85%, depending on the application and purpose. The range can be adjusted.

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

The temperature for thermal imidization in the reaction solution containing the polyimide precursor is 100 to 400 ° C., preferably 120 to 250 ° C., and it is performed while removing water generated by the imidation reaction from the reaction system. preferable.

The catalytic imidation of the polyimide precursor is performed 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. Can do. The amount of the basic catalyst is 0.5 to 30 mol times, preferably 2 to 20 mol times the amidic acid group, and the amount of the acid anhydride is 1 to 50 mol times, preferably 3 to 30 mol times the amido group. 30 mole times.

Examples of the basic catalyst include pyridine, triethylamine, trimethylamine, tributylamine, trioctylamine and the like, and among them, pyridine is preferable in that it has an appropriate basicity for proceeding with the reaction. Examples of the acid anhydride include acetic anhydride, trimellitic anhydride, pyromellitic anhydride, and the like. Among them, acetic anhydride is preferable in that purification after the completion of the reaction is easy. The imidization rate by catalytic imidation can be controlled by adjusting the amount of catalyst, reaction temperature, and reaction time.

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

When recovering polyimide, the polyimide solution may be poured into a poor solvent and precipitated. Examples of the poor solvent used for precipitation include methanol, acetone, hexane, butyl cellosolve, heptane, methyl ethyl ketone, methyl isobutyl ketone, ethanol, toluene, benzene, and water. The polymer put into a poor solvent and precipitated 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 collected by precipitation is redissolved in an organic solvent and reprecipitation and collection 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 kinds of poor solvents selected from these because purification efficiency is further improved. Thus, a purified powdery polyimide containing two or more types of polyimide is obtained.

The molecular weight of each polyimide contained in the powdered polyimide is the weight measured by the GPC (Gel Permeation Chromatography) method in consideration of the strength of the film obtained using the polyimide, the workability at the time of forming the coating film, and the uniformity of the coating film. The average molecular weight is preferably 5,000 to 1,000,000, more preferably 10,000 to 150,000.

Next, in the method for preparing a polyimide varnish of the present invention, the powdered polyimide containing two or more kinds of recovered polyimide dissolves the polyimide powder in the solvent that can be used for the above-described synthesis reaction of the polyimide precursor. It is dissolved in a solvent that can. And in the preparation method of the polyimide varnish of this invention, it can be set as the state which dissolved 2 or more types of polyimide in the solvent, and can prepare a polyimide varnish.

Next, another example of the method for preparing a polyimide varnish containing two or more kinds of polyimides of the present invention will be described.
In another example of the method for preparing a polyimide varnish of the present invention, when preparing a polyimide varnish, first, solutions each containing a polyimide precursor corresponding to each of two or more types of polyimide to be contained are separately prepared. Each of the polyimide precursors contained in each solution is formed from a different combination of tetracarboxylic dianhydride or its derivative and diamine, and has a different structure.

First, imidation of the contained polyimide precursor is performed for each of the solutions containing the polyimide precursor. In this case, the imidation ratio of the polyimide precursor varies depending on the application and purpose, but is preferably adjusted in the range of 40 to 90%, more preferably 45 to 85%. Then, two or more types of polyimides corresponding to the type of polyimide precursor are collected, for example, as powders.
Next, the collected plural kinds of powdery polyimides are mixed to obtain a mixed polyimide powder. Such a plurality of types of powdered polyimides are preferably mixed as much as possible. For this reason, a mixing means such as stirring for 15 minutes or more with a stirring bar or the like is used.
Next, 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.

The preparation method of another example of the polyimide varnish of the present invention is prepared by separately preparing two or more kinds of powdered polyimides, and then mixing them to obtain a mixed polyimide powder, and then dissolving it in a solvent. A polyimide varnish in which two or more types of polyimide are dissolved in a solvent is prepared. Two or more kinds of powdery polyimides are formed from different combinations of tetracarboxylic dianhydride or its derivative and diamine, and have different structures.
Here, N-methyl-2-pyrrolidone, γ-butyrolactone, or the like is used as a solvent for dissolving powdered polyimide.

In another example of the method for preparing the polyimide varnish of the present invention, the tetracarboxylic dianhydride and the diamine that can be selected can be the same as the method for preparing the polyimide varnish described above. And like the preparation method of the polyimide varnish mentioned above, they are made to react and the solution containing a polyimide precursor can be similarly prepared.

The imidation of the polyimide precursor contained in each solution can be performed in the same manner as the imidization in the reaction solution in the above-described method for preparing a polyimide varnish. The same applies to the recovery of polyimide. After obtaining the mixed polyimide powder using the recovered powdered polyimide, dissolve the mixed polyimide powder, such as a solvent that can be used for the synthesis reaction of the polyimide precursor, in the same manner as the polyimide varnish preparation method described above. It is dissolved in a solvent capable of In another example of the method for preparing a polyimide varnish of the present invention, two or more kinds of polyimides are dissolved in a solvent, and a polyimide varnish of another example can be prepared.

[Liquid crystal aligning agent]
The liquid crystal aligning agent of this invention is manufactured using the polyimide varnish obtained by the preparation method of the polyimide varnish of this invention. That is, the polyimide varnish obtained by the method for preparing the polyimide varnish of the present invention can be used as it is as the liquid crystal aligning agent of the present invention.
Moreover, the liquid crystal aligning agent of this invention can also be manufactured by diluting the polyimide varnish obtained by the preparation method of the polyimide varnish of this invention with the suitable solvent mentioned later.
Moreover, the liquid crystal aligning agent of this invention can also be manufactured by further adding the additive mentioned later to the polyimide varnish obtained by the preparation method of the polyimide varnish of this invention.
The liquid crystal aligning agent of this invention is a coating liquid for forming the liquid crystal aligning film used for a liquid crystal display element, and is a solution in which polymers, such as a polyimide contained in the said polyimide varnish, melt | dissolved in the solvent. The liquid crystal aligning agent of this invention is excellent in printability while suppressing generation | occurrence | production of the aggregate.

The solid content concentration in the liquid crystal aligning agent of the present invention can be appropriately changed depending on the setting of the thickness of the liquid crystal aligning film formed using the same, but is preferably 0.5 to 10% by mass. It is more preferable to set it as 8 mass%. When the solid content concentration is less than 0.5% by mass, it is difficult to form a uniform and defect-free coating film. When the solid content concentration exceeds 10% by mass, the storage stability of the solution may be deteriorated. The term “solid content” as used herein refers to a component obtained by removing the solvent from the liquid crystal aligning agent, and means a polymer such as polyimide as described above and an additive described later.

The manufacturing method of the liquid crystal aligning agent of this invention is not specifically limited.
When the polyimide varnish obtained by the method for preparing a polyimide varnish of the present invention is used, it can be produced by diluting it with a solvent to a desired concentration.

The solvent that can be used in the production of the liquid crystal aligning agent of the present invention is not particularly limited as long as it is a solvent that dissolves the resin component. Specific examples are given below.

Specific examples of solvents that can be used include N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methylcaprolactam, 2-pyrrolidone, N-ethyl-2-pyrrolidone, N -Vinylpyrrolidone, dimethyl sulfoxide, tetramethyl urea, pyridine, dimethyl sulfone, hexamethyl sulfoxide, γ-butyrolactone, 3-methoxy-N, N-dimethylpropanamide, 3-ethoxy-N, N-dimethylpropanamide, 3- Butoxy-N, N-dimethylpropanamide, 1,3-dimethyl-imidazolidinone, ethyl amyl ketone, methyl nonyl ketone, methyl ethyl ketone, methyl isoamyl ketone, methyl isopropyl ketone, cyclohexanone, ethylene carbonate, propylene carbonate Over DOO, 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 this invention can contain an additive. Examples of additives include solvents and compounds that improve the film thickness uniformity and surface smoothness when a liquid crystal aligning agent is applied, compounds that improve the adhesion between the liquid crystal alignment film to be formed and the substrate, and thermal stability. For example, an antioxidant for improving the light resistance, and a light stabilizer for improving the light resistance.
The following are mentioned as a specific example of the solvent (poor solvent) which improves the uniformity of film thickness and surface smoothness.

For example, isopropyl alcohol, methoxymethylpentanol, methyl cellosolve, ethyl cellosolve, butyl cellosolve, methyl cellosolve acetate, ethyl cellosolve acetate, butyl carbitol, ethyl carbitol, ethyl carbitol acetate, ethylene glycol, ethylene glycol monoacetate, ethylene glycol monoacetate Isopropyl ether, ethylene glycol monobutyl ether, propylene glycol, propylene glycol monoacetate, propylene glycol monomethyl ether, propylene glycol-tert-butyl ether, dipropylene glycol monomethyl ether, diethylene glycol, diethylene glycol monoacetate, diethylene glycol dimethyl ether, dip Pyrene 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, amyl acetate, butyl butyrate, butyl ether, diisobutyl ketone, methylcyclohexene, propyl ether, dihexyl Ether, 1-hexanol, n-hexane, n-pentane, n-octa , 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, methyl ethyl 3-ethoxypropionate Ethyl 3-methoxypropionate, 3-ethoxypropionic acid, 3-methoxypropionic acid, propyl 3-methoxypropionate, butyl 3-methoxypropionate, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, 1-butoxy-2-propanol, 1-phenoxy-2-propanol, propylene glycol monoacetate, propylene glycol diacetate, propylene glycol-1-monomethyl ether-2-acetate, propylene glycol -1-monoethyl ether-2-acetate, dipropylene glycol, 2- (2-ethoxypropoxy) propanol, lactate methyl ester, lactate ethyl ester, lactate n-propyl ester, lactate n-butyl ester, lactate isoamyl ester, etc. Examples thereof include a solvent having a low surface tension.

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

Examples of compounds that improve film thickness uniformity and surface smoothness include fluorine-based surfactants, silicone-based surfactants, and nonionic surfactants.
More specifically, for example, F-top (registered trademark) EF301, EF303, EF352 (manufactured by Tochem Products), MegaFac (registered trademark) F171, F173, R-30 (manufactured by Dainippon Ink and Co., Ltd.), Florard FC430 FC431 (manufactured by Sumitomo 3M), Asahi Guard (registered trademark) AG710, Surflon (registered trademark) S-382, SC101, SC102, SC103, SC104, SC105, SC106 (manufactured by Asahi Glass Co., Ltd.) and the like. The use ratio of these surfactants is preferably 0.01 to 2 parts by mass, more preferably 0.01 to 1 part by mass with respect to 100 parts by mass of the polymer component contained in the liquid crystal aligning agent. .

Specific examples of the compound that improves the adhesion between the liquid crystal alignment film 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-aminopropyltrimethoxysilane N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-ureidopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, N-ethoxycarbonyl-3-aminopropyltrimethoxysilane, N-ethoxy Carbonyl-3-aminopropyltriethoxysilane, N-triethoxysilylpropyltriethylenetriamine, N-trimethoxysilylpropyltriethylenetriamine, 10-trimethoxysilyl-1,4,7-triazadecane, 10-to Ethoxysilyl-1,4,7-triazadecane, 9-trimethoxysilyl-3,6-diazanonyl acetate, 9-triethoxysilyl-3,6-diazanonyl acetate, N-benzyl-3-aminopropyltri Methoxysilane, N-benzyl-3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltriethoxysilane, N-bis (oxyethylene) -3-amino Propyltrimethoxysilane, N-bis (oxyethylene) -3-aminopropyltriethoxysilane, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether , Polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerin diglycidyl ether, 2,2-dibromoneopentyl glycol diglycidyl ether, 1,3,5,6-tetra Glycidyl-2,4-hexanediol, N, N, N ′, N ′,-tetraglycidyl-m-xylenediamine, 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, N, N, N Examples include ', N',-tetraglycidyl-4,4'-diaminodiphenylmethane.

Specific examples of the compound that improves the thermal stability include the following phenol compounds.
For example, 2,6-di-tert-butyl-p-cresol, 2,6-di-tert-butyl-phenol, 2,4,6-tris (3 ′, 5′-di-tert-butyl-4 ′ -Hydroxybenzyl) mesitylene, pentaerythritol tetrakis [3- (3 ′, 5′-di-tert-butyl-4′-hydroxyphenyl) propionate], acetone bis (3,5-di-tert-butyl-4-hydroxy Phenyl) mercaptol, 4,4′-methylenebis (2,6-di-tert-butylphenol), methyl 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, 4,4′-thiodi (2,6-di-tert-butylphenol), tris (3,5-di-tert-butyl-4-hydroxybenzyl) isocyanuric acid, bis 3,5-di -tert- butyl-4-hydroxybenzyl) sulfide and the like.

Examples of compounds that improve light resistance include the following hindered amine compounds.
For example, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, bis (1,2,2,6 , 6-pentamethyl-4-piperidyl) [[3,5-bis (1,1-dimethylethyl) -4-hydroxyphenyl] methyl] butyl malonate, 1- [2- [3- (3,5- Di-tert-butyl-4-hydroxyphenyl) propionyloxy] ethyl] -4- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy] -2,2,6,6- Tetramethylpiperidine and the like can be mentioned.

[Liquid crystal alignment film and liquid crystal display element]
The liquid crystal aligning agent of the present invention can be applied to a substrate, dried and fired to form a coating film, and the coating film surface is subjected to an alignment treatment such as rubbing treatment or light irradiation to form a liquid crystal alignment film. can do. It is preferable to filter the liquid crystal aligning agent before applying to the substrate.
The liquid crystal aligning agent of the present invention suppresses the generation of aggregates and is excellent in printability, and the liquid crystal alignment film formed therefrom is excellent in in-plane uniformity of characteristics as a liquid crystal alignment film such as a film thickness. Yes.

When applying the liquid crystal aligning agent of this invention to a board | substrate, a highly transparent board | substrate can be used as a board | substrate to be used. As such a substrate, for example, a plastic substrate such as an acrylic substrate or a polycarbonate substrate can be used in addition to a glass substrate.
When using the liquid crystal aligning agent of this invention in manufacture of a liquid crystal display element, it is preferable to form a liquid crystal aligning film using the board | substrate with which the ITO (Indium Tin Oxide) electrode etc. for a liquid crystal drive were formed. In the case of manufacturing a reflective liquid crystal display element, an opaque substrate such as a silicon wafer can be used as long as only one substrate is used. In this case, a material that reflects light such as aluminum may be used for the electrode. it can.

The method for applying the liquid crystal aligning agent of the present invention on the substrate is not particularly limited, but industrially, methods such as screen printing, offset printing, flexographic printing, or ink jet method are common. As other coating methods, there are a dipping method, a roll coater method, a slit coater method, a spinner method, a spray method, and the like, and these may be used according to the purpose.
Even if the liquid crystal aligning agent of this invention is a case where the above apply | coating method is used, applicability | paintability is favorable.

The drying process after applying the liquid crystal aligning agent is not necessarily required, but if the time from application to baking is not constant for each substrate, or if baking is not performed immediately after application, a drying process is included. Is preferred. The drying is not particularly limited as long as the solvent is evaporated to such an extent that the shape of the coating film is not deformed by transporting the substrate or the like. Specific examples include 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.

Calcination of the substrate coated with the liquid crystal aligning agent can be performed at an arbitrary temperature of 100 to 350 ° C. by a heating means such as a hot plate, a thermal circulation oven, or an IR (infrared) oven. The firing temperature is preferably 150 to 300 ° C, more preferably 180 to 250 ° C. However, firing is preferably performed at a temperature higher by 10 ° C. or more than the heat treatment temperature required for the manufacturing process of the liquid crystal display element such as sealing agent curing.

If the thickness of the coating film after baking is too thick, it is disadvantageous in terms of power consumption of the liquid crystal display element, and if it is too thin, the reliability of the liquid crystal display element may be lowered, so it is preferably 10 to 200 nm, more preferably 50 to 100 nm.

For the rubbing treatment of the coating surface formed on the substrate as described above, an existing rubbing apparatus can be used. Examples of the material of the rubbing cloth at this time include cotton, rayon, and nylon.

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 with a liquid crystal aligning film by the method described above.

Next, an example of manufacturing a liquid crystal display element will be described.
A pair of substrates having a liquid crystal alignment film formed using the liquid crystal alignment agent of the present invention is prepared. Next, the pair of substrates is preferably placed with a spacer of 1 to 30 μm, more preferably 2 to 10 μm so that the rubbing direction is an arbitrary angle of 0 to 270 °, and the periphery is sealed with a sealant. Fix it. Next, liquid crystal is injected between the substrates and sealed. The method for enclosing the liquid crystal is not particularly limited, and examples thereof include a vacuum method in which liquid crystal is injected after reducing the pressure inside the manufactured liquid crystal cell, and a dropping method in which sealing is performed after dropping the liquid crystal.

The liquid crystal display device thus produced has a liquid crystal alignment film formed from the liquid crystal aligning agent of the present invention, has no gap unevenness between substrates that sandwich the liquid crystal, and has excellent display quality, Have high reliability.

The following examples further illustrate the present invention. The present invention is not construed as being limited to these.
Abbreviations such as compounds used in Examples and Comparative Examples are as follows.

<Tetracarboxylic dianhydride>
CBDA: 1,2,3,4-cyclobutanetetracarboxylic dianhydride TDA: 3,4-dicarboxy-1,2,3,4-tetrahydro-1-naphthalene succinic dianhydride PMDA: pyromellitic acid dianhydride Anhydride BODA: Bicyclo [3,3,0] octane-2,4,6,8-tetracarboxylic dianhydride TCA: 2,3,5-tricarboxycyclopentylacetic acid dianhydride

<Diamine>
4ABA: 4-aminobenzylamine 3ABA: 3-aminobenzylamine 2,4-DAA: 2,4-diamino-N, N-diallylaniline 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-methyl Amino) methyl) aniline DABFr: 3,5-diaminobenzyl-2-fluorolate PCH7AB: 4- (trans-4-normalheptylcyclohexyl) -2,4-diaminobenzene DDM: 4,4′-diaminodiphenylmethane

<Solvent>
NMP: N-methyl-2-pyrrolidone GBL: γ-butyrolactone BCS: Butyl cellosolve

Hereinafter, various measurement methods and evaluation methods in Examples will be described.
<Measurement of molecular weight>
The molecular weights of polyamic acid and polyimide were determined by measuring the polyimide and the like with a GPC (room temperature gel permeation chromatography) apparatus, and calculating the number average molecular weight and the weight average molecular weight as polyethylene glycol and polyethylene oxide equivalent values.
GPC device: manufactured by Shodex (GPC-101)
Column: manufactured by Shodex (series of KD803 and KD805)
Column temperature: 50 ° C
Eluent: N, N-dimethylformamide (as additives, lithium bromide-hydrate (LiBr · H ₂ O) is 30 mmol / L (liter), phosphoric acid / anhydrous crystal (o-phosphoric acid) is 30 Mmol / L, tetrahydrofuran (THF) 10 ml / L)
Flow rate: 1.0 ml / min Standard sample for preparing calibration curve: TSK standard polyethylene oxide (molecular weight: about 900,000, 150,000, 100,000, and 30000) manufactured by Tosoh Corporation, and polyethylene glycol (molecular weight: about 12,000, 4000, and 1000).

<Measurement of imidization ratio>
The imidation ratio of polyimide was measured as follows.
20 mg of 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 and completely dissolved. 500 MHz proton NMR of this solution was measured with an NMR measuring instrument (JNM-ECA500) manufactured by JEOL Datum. The imidation rate is determined based on protons derived from structures that do not change before and after imidation as reference protons, and the peak integrated value of these protons and proton peaks derived from NH groups of amic acid appearing in the vicinity of 9.5 to 10.0 ppm. It calculated | required by following Formula using the integrated value.
Imidization rate (%) = (1−α · x / y) × 100
In the above formula, x is the proton peak integrated value derived from the NH group of the amic acid, y is the peak integrated value of the reference proton, and α is one NH group proton of the amic acid in the case of polyamic acid (imidation rate is 0%). The number ratio of the reference protons.

<Evaluation of aggregation time>
About 0.1 ml of each polyimide varnish of Examples and Comparative Examples was dropped on a Cr substrate and left in an environment at a temperature of 23 ° C. and a humidity of 45%. The vicinity of the end of the droplet was observed with a microscope every 10 minutes. The observation was performed at a magnification of 100 times. The time when the aggregates were generated was evaluated as the aggregation start time, and the evaluation results of the polyimide varnishes of the examples and comparative examples are listed in Table 1.

(Synthesis Example 1)
As the tetracarboxylic dianhydride component, 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 diamine, 2,4-DAA Of APC12 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 polyamic acid (PAA-1) solution having a concentration of 20% by mass. It was. The viscosity of this polyamic acid solution at 25 ° C. was 597 mPa · s. Moreover, 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 as a tetracarboxylic dianhydride component, 3.30 g (0.027 mol) of 3ABA as a diamine, 2,4-DAA Was reacted at room temperature in 239.1 g of NMP at room temperature for 22 hours to obtain a solution of polyamic acid (PAA-2) with a concentration of 20% by mass using 13.72 g (0.067 mol) of TPBP and 16.51 g (0.041 mol) of TPBP. It was. The viscosity of this polyamic acid solution at 25 ° C. was 693 mPa · s. Moreover, the molecular weight of this polyamic acid was Mn = 20366 and Mw = 54052.

(Synthesis Example 3)
41.62 g (0.139 mol) of TDA was used as the tetracarboxylic dianhydride component, 13.63 g (0.126 mol) of p-PDA and 5.27 g (0.014 mol) of APC18 were used as the diamine component, and NMP238 In 20 g at room temperature to obtain a 20% by mass solution of polyamic acid (PAA-3). The viscosity of this polyamic acid solution at 25 ° C. was 948 mPa · s. Moreover, it was molecular weight Mn = 11244 of this polyamic acid, and Mw = 22915.

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

(Synthesis Example 5)
As tetracarboxylic dianhydride component, 9.51 g (0.048 mol) of CBDA, 4.77 g (0.035 mol) of Me-3ABA as a diamine component, 2.32 g (0.010 mol) of DABFr, CAB- 2 (2.04 g, 0.005 mol) was reacted in 74.6 g of NMP at room temperature for 2 hours to obtain a polyamic acid (PAA-5) solution having a concentration of 20% by mass. The viscosity of this polyamic acid solution at a temperature of 25 ° C. was 584 mPa · s. Moreover, it was molecular weight Mn = 11142, Mw = 32633 of this polyamic acid.

(Synthesis Example 6)
As the tetracarboxylic dianhydride component, 10.87 g (0.048 mol) of TCA, 4.33 g (0.040 mol) of p-PDA and 3.81 g (0.010 mol) of PCH7AB as diamine components were used, and NMP76 Reaction was carried out in 0.0 g at room temperature for 20 hours to obtain a polyamic acid (PAA-6) solution having a concentration of 20 wt%. The viscosity of this polyamic acid solution at a temperature of 25 ° C. was 685 mPa · s. The molecular weight of this polyamic acid was Mn = 11742 and Mw = 23111.

(Synthesis Example 7)
A polyamic acid is prepared by reacting TDA (14.87 g, 0.049 mol) as a tetracarboxylic dianhydride component and 9.91 g (0.05 mol) as a diamine component in NMP (74.6 g) at 50 ° C. for 20 hours. A solution of (PAA-7) having a concentration of 20 wt% was obtained. The viscosity of this polyamic acid solution at a temperature of 25 ° C. was 483 mPa · s. Moreover, it was molecular weight Mn = 9835 of this polyamic acid, and Mw = 20694.

(Example 1)
278.9 g of NMP was added to 276.9 g of the polyamic acid solution (PAA-1) obtained in the same manner as in Synthesis Example 1 and diluted to prepare a polyamic acid solution (PAA-1-2) having a concentration of 8% by mass. did. Next, 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 and diluted to obtain a polyamic acid solution (PAA-2-2) having a concentration of 8% by mass. Was prepared.
Next, 315.0 g of PAA-1-2 and 135.0 g of PAA-2-2 were mixed, and 24.73 g of acetic anhydride and 10.54 g of pyridine were added to 450.0 g of this mixed solution. It was made to react for time and imidized. The obtained polyimide solution was cooled to about room temperature and then poured into 1698 g of methanol to recover the precipitated solid. The solid was washed twice with methanol and then dried under reduced pressure at 100 ° C. to obtain an ocher powder of polyimide (SPI-1). The number average molecular weight of this polyimide was 11529, and the weight average molecular weight was 31363. The imidation ratio was 87%.

80.7 g of GBL was added to 11.0 g of the obtained polyimide (SPI-1), and the mixture was stirred at 50 ° C. for 20 hours. The polyimide was completely dissolved at the end of stirring. 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 ° C. for 20 hours. The solid content (SPI-1) was 5.0% by mass, GBL was 47.5% by mass, A polyimide varnish containing 19.0% by mass of NMP and 28.5% by mass of BCS 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 aggregation start time of the obtained polyimide varnish was evaluated according to the evaluation method described above. The evaluation results are shown in Table 1.

(Example 2)
32.0 g of NMP was added to 22.0 g of the polyamic acid solution (PAA-3) obtained in the same manner as in Synthesis Example 3 and diluted to prepare a polyamic acid solution (PAA-3-2) having a concentration of 8% by mass. did. 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, and 505.0 g of acetic anhydride was added to 275.0 g of this mixed solution. .13 g and pyridine 23.31 g were added and reacted at 40 ° C. for 3 hours to imidize. The obtained polyimide solution was cooled to about room temperature and then poured into 1186 g of methanol, and the precipitated solid was recovered. The solid was washed twice with methanol and then dried under reduced pressure at 100 ° C. to obtain an ocher powder of polyimide (SPI-2). The number average molecular weight of this polyimide was 9967, and the weight average molecular weight was 24637. The imidation ratio was 94%.

To 11.0 g of the obtained polyimide (SPI-2), 80.7 g of GBL was added and stirred at 50 ° C. for 20 hours. The polyimide was completely dissolved at the end of stirring. Furthermore, 23.7 g of GBL, 73.2 g of NMP, and 31.4 g of BCS were added to this solution, and the mixture was stirred at 50 ° C. for 20 hours. The solid content (SPI-2) was 5.0% by mass, GBL was 47.4% by mass, A polyimide varnish having NMP of 33.3 mass% and BCS of 14.3% 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 aggregation start time of the obtained polyimide varnish was evaluated according to the evaluation method described above. The evaluation results are shown in Table 1.

(Example 3)
22.5 g of NMP was added to 15.0 g of the polyamic acid solution (PAA-4) obtained in the same manner as in Synthesis Example 4 and diluted to prepare a polyamic acid solution (PAA-4-2) having a concentration of 8% by mass. did. 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, and 125.0 g of this mixed solution was mixed with 13 acetic anhydride. .26 g and 10.28 g of pyridine were added and reacted at 50 ° C. for 2 hours to imidize. The obtained polyimide solution was cooled to about room temperature, and then poured into 509 g of methanol, and the precipitated solid was recovered. The solid was washed twice with methanol and then dried under reduced pressure at 100 ° C. to obtain an ocher powder of polyimide (SPI-3). The number average molecular weight of this polyimide was 5185, and the weight average molecular weight was 20781. Moreover, the imidation ratio was 50%.
To 7.0 g of the obtained polyimide (SPI-3), 58.3 g of GBL was added and stirred at 50 ° C. for 20 hours. The polyimide was completely dissolved at the end of stirring. Furthermore, GBL8.2g, NMP26.6g, and BCS39.9g were added to this solution, and it stirred at 50 degreeC for 20 hours, solid content (SPI-3) was 5.0 mass%, GBL was 47.5 mass%, A polyimide varnish containing 19.0% by mass of NMP and 28.5% by mass of BCS 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 aggregation start time of the obtained polyimide varnish was evaluated according to the evaluation method described above. The evaluation results are shown in Table 1.

(Example 4)
22.5 g of NMP was added to 15.0 g of the polyamic acid solution (PAA-5) obtained in the same manner as in Synthesis Example 5 and diluted to prepare a polyamic acid solution (PAA-5-2) having a concentration of 8% by mass. did. 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, and 125.0 g of this mixed solution was mixed with acetic anhydride 13 .31 g and 10.31 g of pyridine were added and reacted at 50 ° C. for 2 hours to imidize. The obtained polyimide solution was cooled to about room temperature, and then poured into 513 g of methanol, and the precipitated solid was recovered. The solid was washed twice with methanol and then dried under reduced pressure at 100 ° C. to obtain an ocher powder of polyimide (SPI-4). The number average molecular weight of this polyimide was 9996, and the weight average molecular weight was 26884. Moreover, the imidation ratio was 65%.
To 7.0 g of the obtained polyimide (SPI-4), 58.3 g of GBL was added and stirred at 50 ° C. for 20 hours. The polyimide was completely dissolved at the end of stirring. Furthermore, GBL8.2g, NMP26.6g, and BCS39.9g were added to this solution, and it stirred at 50 degreeC for 20 hours, solid content (SPI-4) was 5.0 mass%, GBL was 47.5 mass%, A polyimide varnish containing 19.0% by mass of NMP and 28.5% by mass of BCS 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 aggregation start time of the obtained polyimide varnish was evaluated according to the evaluation method described above. The evaluation results are shown in Table 1.

(Example 5)
To 350.0 g of the polyamic acid solution (PAA-1-2) obtained in the same manner as in Example 1, 21.08 g of acetic anhydride and 8.99 g of pyridine were added and reacted at 50 ° C. for 2 hours to imidize. The obtained polyimide solution was cooled to about room temperature and then poured into 1330 g of methanol, and the precipitated solid was recovered. The solid was washed twice with methanol and then dried under reduced pressure at 100 ° C. to obtain an ocher powder of polyimide (SPI-5). The number average molecular weight of this polyimide was 10920, and the weight average molecular weight was 31108. The imidation ratio was 80%.

To 260.0 g of the polyamic acid solution (PAA-2-2) obtained in the same manner as in Example 1, 22.26 g of acetic anhydride and 9.49 g of pyridine were added and reacted at 50 ° C. for 2 hours to imidize. The obtained polyimide solution was cooled to about room temperature and then poured into 1511 g of methanol, and the precipitated solid was recovered. The solid was washed twice with methanol and then dried under reduced pressure at 100 ° C. to obtain an ocher powder of polyimide (SPI-6). The number average molecular weight of this polyimide was 13306, and the weight average molecular weight was 35615. Moreover, the imidation ratio was 100%.

Next, 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 ° C. for 20 hours. The polyimide was completely dissolved at the end of stirring. 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 ° C. for 20 hours. The solid content (SPI-5 + SPI-6) was 5.0% by mass, and GBL was 47.5% by mass. %, NMP was 19.0 mass%, and BCS was 28.5 mass%. This polyimide varnish can be used as a liquid crystal aligning agent for forming a liquid crystal alignment film as it is. The aggregation start time of the obtained polyimide varnish was evaluated according to the evaluation method described above. The evaluation results are shown in Table 1.

(Example 6)
To 110.0 g of the polyamic acid solution (PAA-1-2) obtained in the same manner as in Example 1, 52.68 g of acetic anhydride and 24.50 g of pyridine were added and reacted at 40 ° C. for 3 hours to imidize. The obtained polyimide solution was cooled to about room temperature and then poured into 1185 g of methanol, and the precipitated solid was recovered. The solid was washed twice with methanol and then dried under reduced pressure at 100 ° C. to obtain an ocher powder of polyimide (SPI-7). The number average molecular weight of this polyimide was 9781, and the weight average molecular weight was 24985. Moreover, the imidation ratio 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 ° C. for 3 hours to imidize. The obtained polyimide solution was cooled to about room temperature and then poured into 1140 g of methanol to recover the precipitated solid. Further, this solid was washed twice with methanol and then dried under reduced pressure at 100 ° C. to obtain a white powder of polyimide (SPI-8). The number average molecular weight of this polyimide was 11,262, and the weight average molecular weight was 26984. Moreover, the imidation ratio was 90%.

Next, 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 ° C. for 20 hours. The polyimide was completely dissolved at the end of stirring. Further, 23.7 g of GBL, 73.2 g of NMP and 31.4 g of BCS were added to this solution, and the mixture was stirred at 50 ° C. for 20 hours. The solid content (SPI-7 + SPI-8) was 5.0% by mass, and GBL was 47.4% by mass. A polyimide varnish having NMP of 33.3 mass% and BCS of 14.3 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 aggregation start time of the obtained polyimide varnish was evaluated according to the evaluation method described above. The evaluation results are shown in Table 1.

(Example 7)
To 50.0 g of the polyamic acid solution (PAA-4-2) obtained in the same manner as in Example 3, 14.04 g of acetic anhydride and 10.88 g of pyridine were added and reacted at 50 ° C. for 2 hours to imidize. The obtained polyimide solution was cooled to about room temperature and then poured into 539 g of methanol, and the precipitated solid was recovered. The solid was washed twice with methanol and then dried under reduced pressure at 100 ° C. to obtain an ocher powder of polyimide (SPI-9). The number average molecular weight of this polyimide was 5901, and the weight average molecular weight was 24156. Moreover, the imidation ratio was 50%.

Next, 4.9 g of 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 ° C. for 20 hours. The polyimide was completely dissolved at the end of stirring. 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 ° C. for 20 hours. The solid content (SPI-5 + SPI-9) was 5.0% by mass, and GBL was 47.5% by mass. %, NMP was 19.0 mass%, and BCS was 28.5 mass%. This polyimide varnish can be used as a liquid crystal aligning agent for forming a liquid crystal alignment film as it is. The aggregation start time of the obtained polyimide varnish was evaluated according to the evaluation method described above. The evaluation results are shown in Table 1.

(Example 8)
To 450.0 g of the polyamic acid solution (PAA-5-2) obtained in the same manner as in Example 4, 14.45 g of acetic anhydride and 11.20 g of pyridine were added and reacted at 50 ° C. for 2 hours to imidize. The obtained polyimide solution was cooled to about room temperature and then poured into 559 g of methanol, and the precipitated solid was recovered. The solid was washed twice with methanol and then dried under reduced pressure at 100 ° C. to obtain an ocher powder of polyimide (SPI-10). The number average molecular weight of this polyimide was 11133, and the weight average molecular weight was 23773. Moreover, the imidation ratio was 65%.

Next, 4.9 g of 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 ° C. for 20 hours. The polyimide was completely dissolved at the end of stirring. 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 ° C. for 20 hours. The solid content (SPI-5 + SPI-10) was 5.0% by mass, and GBL was 47.5% by mass. %, NMP was 19.0 mass%, and BCS was 28.5 mass%. This polyimide varnish can be used as a liquid crystal aligning agent for forming a liquid crystal alignment film as it is. The aggregation start time of the obtained polyimide varnish was evaluated according to the evaluation method described above. The evaluation results are shown in Table 1.

Example 9
32.0 g of NMP was added to 22.0 g of the polyamic acid solution (PAA-6) obtained in the same manner as in Synthesis Example 6 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 acetic anhydride 58. 07 g and 27.00 g of pyridine were added and reacted at 40 ° C. for 3 hours to imidize. The obtained polyimide solution was cooled to about room temperature and then poured into 1260 g of methanol, and the precipitated solid was recovered. The solid was washed twice with methanol and then dried under reduced pressure at 100 ° C. to obtain an ocher powder of polyimide (SPI-11). The number average molecular weight of this polyimide was 10739, and the weight average molecular weight was 23,093. The imidation ratio was 87%.
To 11.0 g of the obtained polyimide (SPI-11), 80.7 g of GBL was added and stirred at 50 ° C. for 20 hours. The polyimide was completely dissolved at the end of stirring. Further, 23.7 g of GBL, 73.2 g of NMP and 31.4 g of BCS were added to this solution, and the mixture was stirred at 50 ° C. for 20 hours. The solid content (SPI-11) was 5.0 wt%, GBL was 47.4 wt%, and NMP was 33.3%. A polyimide varnish having 3 wt% and 14.3 wt% BCS was obtained. This polyimide varnish becomes a liquid crystal alignment agent for forming a liquid crystal alignment film as it is. The aggregation start time of the obtained polyimide varnish was evaluated according to the evaluation method described above. The evaluation results are shown in Table 1.

(Example 10)
To 50.0 g of the polyamic acid solution (PAA-6-2) obtained in the same manner as in Example 9, 11.71 g of acetic anhydride and 5.45 g of pyridine were added and reacted at 50 ° C. for 3 hours to imidize. The obtained polyimide solution was cooled to about room temperature and then poured into 187 g of methanol, and the precipitated solid was recovered. The solid was washed twice with methanol and then dried under reduced pressure at 100 ° C. to obtain an ocher powder of polyimide (SPI-12). The number average molecular weight of this polyimide was 9879, and the weight average molecular weight was 21571. Moreover, the imidation ratio 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 ° C. for 20 hours. The polyimide was completely dissolved at the end of stirring. Further, 23.7 g of GBL, 73.2 g of NMP and 31.4 g of BCS were added to this solution, and the mixture was stirred at 50 ° C. for 20 hours. The solid content (SPI-5 + SPI-12) was 5.0 wt%, GBL was 47.4 wt%, and NMP was 33 A polyimide varnish having a content of 0.3 wt% and a BCS of 14.3 wt% was obtained. This polyimide varnish becomes a liquid crystal alignment agent for forming a liquid crystal alignment film as it is. The aggregation start time of the obtained polyimide varnish was evaluated according to the evaluation method described above. 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. Then, 43.14 g of acetic anhydride and 20.06 g of pyridine were added to 200.0 g of this mixed solution, and reacted at 50 ° C. for 3 hours to imidize. The obtained polyimide solution was cooled to about room temperature and then poured into 834 g of methanol to recover the precipitated solid. The solid was washed twice with methanol and then dried under reduced pressure at 100 ° C. to obtain an ocher powder of polyimide (SPI-13). This polyimide had a number average molecular weight of 9,986 and a weight average molecular weight of 2,016. Moreover, the imidation ratio was 70%.
80.7 g of GBL was added to 11.0 g of the obtained polyimide (SPI-13), and the mixture was stirred at 50 ° C. for 20 hours. The polyimide was completely dissolved at the end of stirring. Further, 23.7 g of GBL, 73.2 g of NMP and 31.4 g of BCS were added to this solution and stirred at 50 ° C. for 20 hours. The solid content (SPI-13) was 5.0 wt%, GBL was 47.4 wt% and NMP was 33. A polyimide varnish having 3 wt% and 14.3 wt% BCS was obtained. This polyimide varnish becomes a liquid crystal alignment agent for forming a liquid crystal alignment film as it is. The aggregation start time of the obtained polyimide varnish was evaluated according to the evaluation method described above. The evaluation results are shown in Table 1.

Example 12
5.5 g of polyimide (SPI-8) obtained in the same manner as in Example 6 and 5.5 g of polyimide (SPI-10) obtained in the same manner as in Example 8 were mixed, and 80.7 g of GBL was added. Stir at 20 ° C. for 20 hours. The polyimide was completely dissolved at the end of stirring. Further, 23.7 g of GBL, 73.2 g of NMP and 31.4 g of BCS were added to this solution, and the mixture was stirred at 50 ° C. for 20 hours. The solid content (SPI-8 + SPI-10) was 5.0 wt%, GBL was 47.4 wt%, and NMP was 33 A polyimide varnish having a content of 0.3 wt% and a BCS of 14.3 wt% was obtained. This polyimide varnish becomes a liquid crystal alignment agent for forming a liquid crystal alignment film as it is. The aggregation start time of the obtained polyimide varnish was evaluated according to the evaluation method described above. The evaluation results are shown in Table 1.

(Example 13)
60.0 g of NMP was added to 40.0 g of the polyamic acid solution (PAA-7) obtained in the same manner as in Synthesis Example 7 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. 28 g and 14.17 g of pyridine were added and reacted at 50 ° C. for 3 hours to imidize. The obtained polyimide solution was cooled to about room temperature and then poured into 814 g of methanol to recover the precipitated solid. The solid was washed twice with methanol and dried under reduced pressure at 100 ° C. to obtain an ocher powder of polyimide (SPI-14). The number average molecular weight of this polyimide was 10917, and the weight average molecular weight was 22582. Moreover, the imidation ratio was 85%.
To 11.0 g of the obtained polyimide (SPI-14), 80.7 g of GBL was added and stirred at 50 ° C. for 20 hours. The polyimide was completely dissolved at the end of stirring. Further, 23.7 g of GBL, 73.2 g of NMP and 31.4 g of BCS were added to this solution and stirred at 50 ° C. for 20 hours. The solid content (SPI-14) was 5.0 wt%, GBL was 47.4 wt% and NMP was 33. A polyimide varnish having 3 wt% and 14.3 wt% BCS was obtained. This polyimide varnish becomes a liquid crystal alignment agent for forming a liquid crystal alignment film as it is. The aggregation start time of the obtained polyimide varnish was evaluated according to the evaluation method described above. The evaluation results are shown in Table 1.

(Example 14)
To 100.0 g of the polyamic acid solution (PAA-7-2) obtained in the same manner as in Example 13, 16.38 g of acetic anhydride and 7.62 g of pyridine were added and reacted at 50 ° C. for 3 hours to imidize. The obtained polyimide solution was cooled to about room temperature and then poured into 345 g of methanol, and the precipitated solid was recovered. The solid was washed twice with methanol and then dried under reduced pressure at 100 ° C. to obtain an ocher powder of polyimide (SPI-15). The number average molecular weight of this polyimide was 10003, and the weight average molecular weight was 21093. Further, the imidization ratio was 83%.
Next, 5.5 g of 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 ° C. for 20 hours. The polyimide was completely dissolved at the end of stirring. Further, 23.7 g of GBL, 73.2 g of NMP and 31.4 g of BCS were added to this solution, and the mixture was stirred at 50 ° C. for 20 hours. The solid content (SPI-6 + SPI-15) was 5.0 wt%, GBL was 47.4 wt%, and NMP was 33 A polyimide varnish having a content of 0.3 wt% and a BCS of 14.3 wt% was obtained. This polyimide varnish becomes a liquid crystal alignment agent for forming a liquid crystal alignment film as it is. The aggregation start time of the obtained polyimide varnish was evaluated according to the evaluation method described above. 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. Then, 22.46 g of acetic anhydride and 17.40 g of pyridine were added to 200.0 g of this mixed solution, and reacted at 50 ° C. for 3 hours to imidize. The obtained polyimide solution was cooled to about room temperature and then poured into 840 g of methanol, and the precipitated solid was recovered. The solid was washed twice with methanol and then dried under reduced pressure at 100 ° C. to obtain an ocher powder of polyimide (SPI-16). The number average molecular weight of this polyimide was 9765, and the weight average molecular weight was 21724. Moreover, the imidation ratio was 61%.
To 11.0 g of the obtained polyimide (SPI-16), 80.7 g of GBL was added and stirred at 50 ° C. for 20 hours. The polyimide was completely dissolved at the end of stirring. Further, 23.7 g of GBL, 73.2 g of NMP and 31.4 g of BCS were added to this solution and stirred at 50 ° C. for 20 hours. The solid content (SPI-16) was 5.0 wt%, GBL was 47.4 wt% and NMP was 33. A polyimide varnish having 3 wt% and 14.3 wt% BCS was obtained. This polyimide varnish becomes a liquid crystal alignment agent for forming a liquid crystal alignment film as it is. The aggregation start time of the obtained polyimide varnish was evaluated according to the evaluation method described above. The evaluation results are shown in Table 1.

(Example 16)
5.5 g of polyimide (SPI-9) obtained in the same manner as in Example 7 and 5.5 g of polyimide (SPI-15) obtained in the same manner as in Example 14 were mixed, and 80.7 g of GBL was added. Stir at 20 ° C. for 20 hours. The polyimide was completely dissolved at the end of stirring. Further, 23.7 g of GBL, 73.2 g of NMP and 31.4 g of BCS were added to this solution and stirred at 50 ° C. for 20 hours. The solid content (SPI-9 + SPI-15) was 5.0 wt%, GBL was 47.4 wt% and NMP was 33 A polyimide varnish having a content of 0.3 wt% and a BCS of 14.3 wt% was obtained. This polyimide varnish becomes a liquid crystal alignment agent for forming a liquid crystal alignment film as it is. The aggregation start time of the obtained polyimide varnish was evaluated according to the evaluation method described above. The evaluation results are shown in Table 1.

(Comparative Example 1)
To 11.0 g of polyimide (SPI-5) obtained in the same manner as in Example 5, 80.7 g of GBL was added and stirred at 50 ° C. for 20 hours. The polyimide was completely dissolved at the end of stirring. Further, 23.8 g of GBL, 41.8 g of NMP, and 62.7 g of BCS were added to this solution and stirred at 50 ° C. for 20 hours. The solid content (SPI-5) was 5.0% by mass, GBL was 47.5% by mass, A polyimide solution having NMP of 19.0% by mass and BCS of 28.5% by mass was obtained.
To 11.0 g of polyimide (SPI-6) obtained in the same manner as in Example 5, 80.7 g of GBL was added and stirred at 50 ° C. for 20 hours. The polyimide was completely dissolved at the end of stirring. 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 ° C. for 20 hours. The solid content (SPI-6) was 5.0% by mass, GBL was 47.5% by mass, A polyimide solution having NMP of 19.0% by mass and BCS of 28.5% by mass was obtained.
Next, 140 g of the polyimide solution obtained above (SPI-5 concentration is 5.0 mass%) and 60 g of the polyimide solution (SPI-6 concentration is 5.0 mass%) are mixed and stirred at room temperature for 2 hours. A polyimide varnish having a solid content (SPI-5 + SPI-6) of 5.0% by mass, GBL of 47.5% by mass, NMP of 19.0% by mass and BCSga of 28.5% by mass was obtained. The aggregation start time of the obtained polyimide varnish was evaluated according to the evaluation method described above. The evaluation results are shown in Table 1.

(Comparative Example 2)
GBL80.7g was added to 11.0g of polyimides (SPI-7) obtained by carrying out similarly to Example 6, and it stirred at 50 degreeC for 20 hours. The polyimide was completely dissolved at the end of stirring. Furthermore, GBL23.7g, NMP73.2g, and BCS31.4g were added to this solution, and it stirred at 50 degreeC for 20 hours, solid content (SPI-7) was 5.0 mass%, GBL was 47.4 mass%, A polyimide solution having NMP of 33.3% by mass and BCS of 14.3% by mass was obtained.
GBL80.7g was added to 11.0g of polyimides (SPI-8) obtained by carrying out similarly to Example 6, and it stirred at 50 degreeC for 20 hours. The polyimide was completely dissolved at the end of stirring. 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 ° C. for 20 hours. The solid content (SPI-8) was 5.0% by mass, GBL was 47.4% by mass, A polyimide solution having NMP of 33.3% by mass and BCS of 14.3% by mass was obtained.
Next, 140 g of the polyimide solution obtained above (SPI-7 concentration 5.0 mass%) and 60 g polyimide solution (SPI-8 concentration 5.0 mass%) were mixed and stirred at room temperature for 2 hours. Thus, a polyimide varnish having a solid content (SPI-7 + SPI-8) of 5.0% by mass, GBL of 47.4% by mass, NMP of 33.3% by mass, and BCS of 14.3% by mass was obtained. The aggregation start time of the obtained polyimide varnish was evaluated according to the evaluation method described above. The evaluation results are shown in Table 1.

(Comparative Example 3)
To 7.0 g of polyimide (SPI-9) obtained in the same manner as in Example 7, 58.3 g of GBL was added and stirred at 50 ° C. for 20 hours. The polyimide was completely dissolved at the end of stirring. Furthermore, GBL8.2g, NMP26.6g, and BCS39.9g were added to this solution, and it stirred at 50 degreeC for 20 hours, solid content (SPI-9) was 5.0 mass%, GBL was 47.5 mass%, A polyimide solution having NMP of 19.0% by mass and BCS of 28.5% by mass was obtained.
To 7.0 g of polyimide (SPI-5) obtained in the same manner as in Example 5, 58.3 g of GBL was added and stirred at 50 ° C. for 20 hours. The polyimide was completely dissolved at the end of stirring. Furthermore, GBL8.2g, NMP26.6g, and BCS39.9g were added to this solution, and it stirred at 50 degreeC for 20 hours, solid content (SPI-5) was 5.0 mass%, GBL was 47.5 mass%, A polyimide solution having NMP of 19.0% by mass and BCS of 28.5% by mass was obtained.
Next, 140 g of the polyimide solution obtained above (SPI-5 concentration 5.0 mass%) and 60 g polyimide solution (SPI-9 concentration 5.0 mass%) were mixed and stirred at room temperature for 2 hours. Thus, a polyimide varnish having a solid content (SPI-5 + SPI-9) of 5.0% by mass, GBL of 47.5% by mass, NMP of 19.0% by mass, and BCS of 28.5% by mass was obtained. The aggregation start time of the obtained polyimide varnish was evaluated according to the evaluation method described above. The evaluation results are shown in Table 1.

(Comparative Example 4)
To 7.0 g of polyimide (SPI-10) obtained in the same manner as in Example 8, 58.3 g of GBL was added and stirred at 50 ° C. for 20 hours. The polyimide was completely dissolved at the end of stirring. Furthermore, GBL8.2g, NMP26.6g, and BCS39.9g were added to this solution, and it stirred at 50 degreeC for 20 hours, solid content (SPI-10) was 5.0 mass%, GBL was 47.5 mass%, A polyimide solution having NMP of 19.0% by mass and BCS of 28.5% by mass was obtained.
GBL58.3g was added to 7.0g of polyimides (SPI-5) obtained by carrying out similarly to Example 5, and it stirred at 50 degreeC for 20 hours. The polyimide was completely dissolved at the end of stirring. Furthermore, GBL8.2g, NMP26.6g, and BCS39.9g were added to this solution, and it stirred at 50 degreeC for 20 hours, solid content (SPI-5) was 5.0 mass%, GBL was 47.5 mass%, A polyimide solution having NMP of 19.0% by mass and BCS of 28.5% by mass was obtained.
Next, 140 g of the polyimide solution obtained above (SPI-5 concentration is 5.0 mass%) and 60 g of the polyimide solution (SPI-10 concentration is 5.0 mass%) are mixed and stirred at room temperature for 2 hours. Thus, a polyimide varnish having a solid content (SPI-5 + SPI-10) of 5.0% by mass, GBL of 47.5% by mass, NMP of 19.0% by mass, and BCS of 28.5% by mass was obtained. The aggregation start time of the obtained polyimide varnish was evaluated according to the evaluation method described above. The evaluation results are shown in Table 1.

(Comparative Example 5)
To 11.0 g of polyimide (SPI-5) obtained in the same manner as in Example 5, 80.7 g of GBL was added and stirred at 50 ° C. for 20 hours. The polyimide was completely dissolved at the end of stirring. Further, 23.7 g of GBL, 73.2 g of NMP and 31.4 g of BCS were added to this solution and stirred at 50 ° C. for 20 hours. The solid content (SPI-5) was 5.0 wt%, GBL was 47.4 wt% and NMP was 33. A polyimide solution with 3 wt% and BCS 14.3 wt% was obtained.
GBL80.7g was added to 11.0g of polyimides (SPI-12) obtained by carrying out similarly to Example 10, and it stirred at 50 degreeC for 20 hours. The polyimide was completely dissolved at the end of stirring. 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 ° C. for 20 hours. The solid content (SPI-12) was 5.0 wt%, GBL was 47.4 wt% and NMP was 33. A polyimide solution with 3 wt% and BCS 14.3 wt% was obtained.
Next, 160 g of polyimide solution (SPI-5 concentration 5.0 wt%) and 40 g of polyimide solution (SPI-12 concentration 5.0 wt%) were mixed and stirred at room temperature for 2 hours to obtain a solid content (SPI-5 + SPI-12) 5 An alignment material having 0.0 wt%, GBL 47.4 wt%, NMP 33.3 wt%, and BCS 14.3 wt% was obtained. A polyimide varnish was obtained. The aggregation start time of the obtained polyimide varnish was evaluated according to the evaluation method described above. The evaluation results are shown in Table 2.

(Comparative Example 6)
GBL80.7g was added to 11.0g of polyimides (SPI-8) obtained by carrying out similarly to Example 6, and it stirred at 50 degreeC for 20 hours. The polyimide was completely dissolved at the end of stirring. Further, 23.7 g of GBL, 73.2 g of NMP and 31.4 g of BCS were added to this solution, and the mixture was stirred at 50 ° C. for 20 hours. The solid content (SPI-8) was 5.0 wt%, GBL was 47.4 wt%, and NMP was 33. A polyimide solution with 3 wt% and BCS 14.3 wt% was obtained.
GBL80.7g was added to 11.0g of polyimides (SPI-10) obtained by carrying out similarly to Example 8, and it stirred at 50 degreeC for 20 hours. The polyimide was completely dissolved at the end of stirring. Further, 23.8 g of GBL, 41.8 g of NMP, and 62.7 g of BCS were added to this solution, followed by stirring at 50 ° C. for 20 hours. The solid content (SPI-10) was 5.0 wt%, GBL was 47.4 wt%, and NMP was 33. A polyimide solution with 3 wt% and BCS 14.3 wt% was obtained.
Next, 100 g of polyimide solution (SPI-8 concentration 5.0 wt%) and 100 g of polyimide solution (SPI-10 concentration 5.0 wt%) were mixed and stirred at room temperature for 2 hours to obtain a solid content (SPI-8 + SPI-10) 5 An alignment material having 0.0 wt%, GBL 47.4 wt%, NMP 33.3 wt%, and BCS 14.3 wt% was obtained. A polyimide varnish was obtained. The aggregation start time of the obtained polyimide varnish was evaluated according to the evaluation method described above. The evaluation results are shown in Table 2.

(Comparative Example 7)
To 11.0 g of polyimide (SPI-6) obtained in the same manner as in Example 5, 80.7 g of GBL was added and stirred at 50 ° C. for 20 hours. The polyimide was completely dissolved at the end of stirring. Further, 23.7 g of GBL, 73.2 g of NMP, and 31.4 g of BCS were added to this solution, followed by stirring at 50 ° C. for 20 hours. The solid content (SPI-6) was 5.0 wt%, GBL was 47.4 wt%, and NMP was 33. A polyimide solution with 3 wt% and BCS 14.3 wt% was obtained.
To 11.0 g of polyimide (SPI-15) obtained in the same manner as in Example 14, 80.7 g of GBL was added and stirred at 50 ° C. for 20 hours. The polyimide was completely dissolved at the end of stirring. Further, 23.8 g of GBL, 41.8 g of NMP and 62.7 g of BCS were added to this solution and stirred at 50 ° C. for 20 hours. The solid content (SPI-15) was 5.0 wt%, GBL was 47.4 wt% and NMP was 33. A polyimide solution with 3 wt% and BCS 14.3 wt% was obtained.
Next, 100 g of polyimide solution (SPI-6 concentration 5.0 wt%) and 100 g of polyimide solution (SPI-15 concentration 5.0 wt%) were mixed and stirred at room temperature for 2 hours to obtain a solid content (SPI-6 + SPI-15) 5 An alignment material having 0.0 wt%, GBL 47.4 wt%, NMP 33.3 wt%, and BCS 14.3 wt% was obtained. A polyimide varnish was obtained. The aggregation start time of the obtained polyimide varnish was evaluated according to the evaluation method described above. The evaluation results are shown in Table 2.

(Comparative Example 8)
GBL80.7g was added to 11.0g of polyimides (SPI-9) obtained by carrying out similarly to Example 7, and it stirred at 50 degreeC for 20 hours. The polyimide was completely dissolved at the end of stirring. Further, 23.7 g of GBL, 73.2 g of NMP and 31.4 g of BCS were added to this solution and stirred at 50 ° C. for 20 hours. The solid content (SPI-9) was 5.0 wt%, GBL was 47.4 wt% and NMP was 33. A polyimide solution with 3 wt% and BCS 14.3 wt% was obtained.
To 11.0 g of polyimide (SPI-15) obtained in the same manner as in Example 14, 80.7 g of GBL was added and stirred at 50 ° C. for 20 hours. The polyimide was completely dissolved at the end of stirring. Further, 23.8 g of GBL, 41.8 g of NMP and 62.7 g of BCS were added to this solution and stirred at 50 ° C. for 20 hours. The solid content (SPI-15) was 5.0 wt%, GBL was 47.4 wt% and NMP was 33. A polyimide solution with 3 wt% and BCS 14.3 wt% was obtained.
Next, 100 g of polyimide solution (SPI-9 concentration 5.0 wt%) and 100 g of polyimide solution (SPI-15 concentration 5.0 wt%) were mixed and stirred at room temperature for 2 hours to obtain a solid content (SPI-9 + SPI-15) 5 An alignment material having 0.0 wt%, GBL 47.4 wt%, NMP 33.3 wt%, and BCS 14.3 wt% was obtained. A polyimide varnish was obtained. The aggregation start time of the obtained polyimide varnish was evaluated according to the evaluation method described above. The evaluation results are shown in Table 2.

In Tables 1 and 2, a column for preparing a polyimide varnish is provided. In Examples 1 to 4, 9, 11, 13, and 15, two types of polyimide precursor solutions are mixed to obtain a reaction solution. Obtained and imidized as it is, a polyimide solution in which two kinds of polyimides were dissolved in a solvent was obtained, and a polyimide varnish was prepared. 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 kinds of powdered polyimides were separately prepared, mixed, and then dissolved in a solvent, and two kinds of polyimide were dissolved in the solvent. A polyimide solution is obtained and a polyimide varnish is prepared. 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 powdered polyimides were prepared separately, and each was dissolved in a solvent to obtain two kinds of polyimide solutions, and then each polyimide solution was mixed to obtain two kinds of polyimides. A polyimide varnish is prepared by obtaining a polyimide solution in which is dissolved in a solvent. The varnish preparation methods of Comparative Examples 1 to 8 are described as “III” in Table 1.

In the column of components in Tables 1 and 2, the polyamic acid solutions (PAA-1 to PAA-7) used in Examples and Comparative Examples are listed as main components.

As shown in Table 1, the polyimide varnishes of Examples 1 to 4, 9, 11, 13 and 15 are comparative examples in which the polyamic acid solutions (PAA-1 to PAA-7) used are the same and the varnish preparation methods are different. Compared with 1 to 8, it was found that the aggregation start time was longer and the generation of aggregates during the formation of the coating film hardly occurred.
Similarly, in the polyimide varnishes of Examples 5 to 8, 10, 12, 14 and 16, the polyamic acid solutions (PAA-1 to PAA-7) used were the same, and Comparative Examples 1 to 8 having different varnish preparation methods were used. In comparison, it was found that the aggregation start time was long and the generation of aggregates during the formation of the coating film hardly occurred.

From the above, it was found that the polyimide varnishes of Examples 1 to 16 can provide a liquid crystal aligning agent in which aggregates are hardly generated when a coating film is formed.
In addition, it was found that the liquid crystal aligning agents using the polyimide varnishes of Examples 1 to 4 are particularly suitable for suppressing the generation of aggregates during the formation of the coating film.

The polyimide varnish obtained by the method for preparing a polyimide varnish of the present invention is suitably used as a liquid crystal aligning agent having characteristics that it is excellent in printability and is difficult to form an aggregate during coating film formation.
In addition, a liquid crystal display element having a liquid crystal alignment film formed using the liquid crystal aligning agent of the present invention has a high display quality with excellent display uniformity, and displays a large liquid crystal TV or a high-definition image. It can use suitably as a display element for portable information terminals, such as a smart phone.

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

Claims (14)

1. A method for preparing a polyimide varnish comprising imidizing each of the polyimide precursors in a solution containing two or more types of polyimide precursors, and dissolving and containing two or more types of polyimides.
2. The method for preparing a polyimide varnish according to claim 1, wherein the concentration of the polyimide precursor in the solution is 1 to 12% by mass.
3. The polyimide according to claim 1 or 2, wherein the imidization of the polyimide precursor in the solution is performed after 10 minutes to 12 hours have elapsed after preparing the solution containing the two or more types of polyimide precursors. Preparation method of varnish.
4. At least one of the two or more types of polyimide precursors is 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 3,4-dicarboxy-1,2,3,4-tetrahydro-1-naphthalene The polyimide precursor formed by using at least one selected from the group consisting of succinic dianhydride and aromatic tetracarboxylic dianhydride containing an aromatic ring. Preparation method of polyimide varnish as described in 2.
5. A method for preparing a polyimide varnish comprising mixing two or more types of polyimide in a powder state, dissolving the mixed polyimide powder in a solvent, and dissolving and containing two or more types of polyimide.
6. At least one of the two or more types of polyimides is 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 3,4-dicarboxy-1,2,3,4-tetrahydro-1-naphthalene succinate. 6. The polyimide obtained by imidizing a polyimide precursor formed using at least one selected from the group consisting of an acid dianhydride and an aromatic tetracarboxylic dianhydride containing an aromatic ring. Preparation method of polyimide varnish.
7. The method for preparing a polyimide varnish according to any one of claims 1 to 6, wherein the polyimide has a weight average molecular weight of 10,000 to 150,000.
8. A polyimide varnish obtained by using the method for preparing a polyimide varnish according to any one of claims 1 to 7.
9. A polyimide varnish obtained by using the method for preparing a polyimide varnish according to any one of claims 5 to 7.
10. Liquid crystal aligning agent obtained using the polyimide varnish of Claim 8 or 9.
11. The liquid crystal aligning agent according to claim 10, further comprising at least one selected from the group consisting of N-methyl-2-pyrrolidone and γ-butyrolactone.
12. A liquid crystal alignment film obtained from the liquid crystal aligning agent according to claim 10 or 11.
13. The liquid crystal alignment film according to claim 12, wherein the film thickness is 10 to 200 μm.
14. A liquid crystal display device comprising the liquid crystal alignment film according to claim 12.