WO2009148100A1

WO2009148100A1 - Liquid crystal aligning agent and liquid crystal display element using same

Info

Publication number: WO2009148100A1
Application number: PCT/JP2009/060200
Authority: WO
Inventors: 尚士鉄谷; 皇晶筒井; 啓文志田
Original assignee: 日産化学工業株式会社
Priority date: 2008-06-04
Filing date: 2009-06-03
Publication date: 2009-12-10
Also published as: CN102084287A; JPWO2009148100A1; KR101589328B1; TWI471656B; TW201011421A; KR20110020867A; JP5578075B2; CN102084287B

Abstract

Provided are a liquid crystal aligning agent with good whitening and printing performance which generates no aggregate that causes an uneven gap in a liquid crystal panel during printing while maintaining the good electric property of a polyimide alignment film, and a liquid crystal alignment film and a liquid crystal display element which are obtained by using the same. The liquid crystal aligning agent is characterized by containing a resin component containing polyimide obtained by imidizing a polyamic acid obtained by a reaction between a diamine component and a tetracarboxylic dianhydride, and a solvent component containing a pyrrolidone compound composed of N-ethyl-pirrolidone or N-cyclohexyl-2-pyrrolidone, and the liquid crystal alignment film and the liquid crystal display element are obtained by using the same.

Description

Liquid crystal alignment treatment agent and liquid crystal display element using the same

The present invention relates to a liquid crystal alignment treatment agent used for a liquid crystal display element, a liquid crystal alignment film using the same, and a liquid crystal display element.

A liquid crystal display element has a structure in which liquid crystal molecules are sandwiched between liquid crystal alignment films formed on a substrate, and is a display element utilizing the fact that liquid crystal molecules aligned in a certain direction by a liquid crystal alignment film respond with voltage. is there. This liquid crystal alignment film is generally produced by subjecting the surface of a polyimide film formed on a substrate with electrodes to a so-called “rubbing process” in which pressure is applied to the surface with rayon or nylon cloth. . In addition, VA (abbreviation for Vertical Alignment) alignment films that do not undergo rubbing treatment, and photo alignment films that align the liquid crystal by applying anisotropy to the film surface by irradiating polarized UV light have attracted attention.

As a means of forming a polyimide film on a substrate with electrodes, a method of creating a coating film using a solution of a polyimide precursor such as polyamic acid and imidizing on the substrate, and a polyimide that has been imidized in advance are used. And a method using a solution containing the same.

Among them, the method using a polyimide-containing solution was able to form a polyimide film with good characteristics when used as a liquid crystal alignment film, even when firing at a relatively low temperature. There is a problem that the strength of the film is low and the rubbing treatment tends to cause scratches or peeling of the film surface. Scratches and peeling on the surface of the liquid crystal alignment film are important problems because they cause display defects when the liquid crystal display element is formed. In addition, polyimide is generally inferior in solubility in organic solvents compared to polyamic acid and the like, so if imidized in advance, it may be difficult to form a uniform coating film. It may happen that the composition is insolubilized in a solvent commonly used for the agent and cannot be contained in the liquid crystal aligning agent. Therefore, the solubility of the polyimide contained in the liquid crystal aligning agent is also important. In addition, when a liquid crystal aligning agent containing polyimide is used, when printing on a substrate, the varnish containing polyimide is whitened by moisture absorption, or the varnish is dried on the printing plate and aggregates are generated. The problem was easy to happen.

In response to the above problems, a liquid crystal alignment treatment agent containing a diamine component having a specific structure has been proposed as an excellent liquid crystal alignment film rubbing resistance and polyimide solubility (for example, see Patent Document 1). ). As a method for suppressing the whitening phenomenon of varnish containing polyimide, it has been proposed to use N-vinylpyrrolidone or N-cyclohexylpyrrolidone for 50% or more of the solvent (for example, see Patent Document 2). However, a liquid crystal aligning agent that suppresses aggregates produced by drying of the varnish has not been proposed so far.

凝集 Agglomerates due to drying of the varnish are characterized by being easily generated at the edge of the printing plate. For this reason, even if some agglomerates are generated, there is no particular problem unless they are present in the pixel. However, in recent years, in order to realize a high-speed response of the liquid crystal panel, the narrowing of the panel is progressing. As described above, since the distance between the two substrates constituting the liquid crystal cell is narrowed, the agglomerates as described above, which were not a problem unless they existed in the pixel in the past, are caused by the gap unevenness of the panel. The number of cases has increased.

International Publication No. 2006/126555 Pamphlet Japanese Patent Laid-Open No. 5-117487

As a result of investigations by the present inventors, it has been found that aggregates that cause panel gap unevenness are generated regardless of the whitening phenomenon caused by moisture absorption of the varnish.
In view of the above situation, the present invention is a liquid crystal alignment treatment agent that maintains good electrical characteristics of a polyimide alignment film, has good whitening and printability, and does not generate aggregates that cause gap unevenness in a liquid crystal panel during printing. The purpose is to provide. Furthermore, in addition to characteristics such as whitening, printability, and aggregates, the liquid crystal alignment treatment agent is also excellent in long-term storage stability, and when used as a liquid crystal alignment film, it has excellent rubbing resistance and a liquid crystal tilt angle. An object of the present invention is to provide a liquid crystal alignment treatment agent that is high and has good alignment properties.

As a result of intensive studies to achieve the above object, the present inventors have completed the present invention. That is, the gist of the present invention is as follows.
1. A pyrrolidone compound comprising a resin component containing a polyimide obtained by imidizing a polyamic acid obtained by reacting a diamine component with tetracarboxylic dianhydride, and N-ethyl-2-pyrrolidone or N-cyclohexyl-2-pyrrolidone And a solvent component comprising: a liquid crystal aligning agent characterized by comprising:
2. 2. The liquid crystal aligning agent according to 1 above, wherein the pyrrolidone compound is N-ethyl-2-pyrrolidone, and the N-ethyl-2-pyrrolidone is 5 to 80% by mass of the solvent component.
3. 2. The liquid crystal aligning agent according to 1 above, wherein the pyrrolidone compound is N-cyclohexyl-2-pyrrolidone, and the N-cyclohexyl-2-pyrrolidone is 5 to 40% by mass of the solvent component.
4). 4. The liquid crystal aligning agent according to any one of 1 to 3 above, wherein the resin component is contained in an amount of 1 to 10% by mass and the solvent component is contained in an amount of 90 to 99% by mass.
5). 5. The liquid crystal aligning agent according to any one of the above 1 to 4, comprising diaminobenzene having a disubstituted amino group substituted with an alkenyl group having 2 or 3 carbon atoms as a diamine component.
6). 6. The liquid crystal aligning agent according to 5 above, wherein the diaminobenzene having a disubstituted amino group substituted with an alkenyl group having 2 or 3 carbon atoms is a diamine represented by the following formula [1].

7). 7. The liquid crystal aligning agent according to 6 above, wherein the diamine component further contains a diamine represented by the following formula.

(In the above formula, k represents an integer of 1 to 20.)
8). 7. The liquid crystal aligning agent according to 6 above, wherein the diamine represented by the formula [1] is contained in an amount of 20 to 90 mol% in all diamine components.
9. The liquid crystal aligning agent according to claim 8, wherein the diamine represented by the formula [32] is contained in an amount of 5 to 40 mol% in all diamine components.
10. 10. A liquid crystal alignment film obtained by applying and baking the liquid crystal aligning agent according to any one of 1 to 9 above on a substrate with an electrode.
11. 11. A liquid crystal display device having the liquid crystal alignment film as described in 10 above.

According to the liquid crystal alignment treatment agent of the present invention, a liquid crystal alignment film having good electrical characteristics can be obtained, and the occurrence of aggregates that cause gap unevenness of the liquid crystal panel during printing is suppressed, so that reliability of a narrow gap is improved. LCD panels with high yield can be produced with good yield.

The present invention is described in detail below.
The liquid crystal aligning agent of this invention is a processing agent which forms the liquid crystal aligning film used for a liquid crystal display element, and is obtained by imidating the polyamic acid obtained by making a diamine component and tetracarboxylic dianhydride react. It contains polyimide and N-ethyl-2-pyrrolidone or N-cyclohexyl-2-pyrrolidone. Although the structure of the polyimide used in the present invention is not particularly limited, a diamine component containing a diaminobenzene having a disubstituted amino group substituted with an alkenyl group having 2 or 3 carbon atoms (hereinafter referred to as a specific diamine), tetra The use of a polyimide obtained by imidizing a polyamic acid obtained by reacting with a carboxylic dianhydride component is particularly preferred because the solubility in an organic solvent is increased.

[Diamine component]
The diamine component (also simply referred to as diamine) used in the present invention is not particularly limited. The diamine can be used alone or in combination, and the type is not limited. Examples of the diamine include alicyclic diamines, aromatic diamines, heterocyclic diamines, and aliphatic diamines. Specific examples are shown below.

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

Examples of aromatic diamines include o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, 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′-dia Nostilbene, 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, bis [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-aminophenyl) te Lamethyldisiloxane, benzidine, 2,2'-dimethylbenzidine, 1,2-bis (4-aminophenyl) ethane, 1,3-bis (4-aminophenyl) propane, 1,4-bis (4-amino) Phenyl) 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-aminophen Xyl) 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 -Geoate, 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-bis [4- (4 -Aminophenoxy) phenoxy] butane, 1,5-bis [4- (4-aminophenoxy) phenoxy] pentane, 1,6-bis [4- (4-aminophenoxy) phenoxy] hexane, 1,7-bis [ 4- (4-aminophenoxy) phenoxy] heptane, 1,8-bis [4- (4-aminophenoxy) phenoxy] octane, 1,9-bis [4- (4-aminophenoxy) phenoxy] nonane, 1, And 10-bis [4- (4-aminophenoxy) phenoxy] decane.

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

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-methylheptane, 1,12-diaminododecane 1,18-diaminooctadecane, 1,2-bis (3-aminopropoxy) ethane and the like.

In the present invention, a diaminobenzene having a disubstituted amino group substituted with an alkenyl group having 2 or 3 carbon atoms (hereinafter also referred to as a specific diamine) is preferable as the diamine in order to increase the solubility of polyimide in an organic solvent. Used for. In particular, diaminobenzene having a disubstituted amino group substituted by a 2-propenyl group (hereinafter also referred to as an allyl group) represented by the following formula [1] is preferable.

In the diamine represented by the formula [1], the position of each substituent on the benzene ring is not particularly limited, but the positional relationship between the two amino groups is preferably meta or para. The more preferable specific example of this diamine is given below.

The formula [2] is 2,4-diamino-N, N-diallylaniline, the formula [3] is 3,5-diamino-N, N-diallylaniline, and the formula [4] is 2,5-diamino-N, N-diallylaniline. More preferably, the diaminobenzene is at least one selected from the group consisting of [2], [3] and [4]. Among these, the diaminobenzene is particularly preferably 2,4-diamino-N, N-diallylaniline.

In the present invention, the diamine component used as a raw material for polyimide may be only a specific diamine, or a combination of a specific diamine and one or more of other diamines. By making a diamine component for obtaining a polyimide contain a specific diamine, the solubility of the polyimide in an organic solvent is increased. Furthermore, problems such as scratches on the film surface and film peeling when the coating film is rubbed are improved.

The content of the specific diamine in the diamine component is preferably 20 mol (mol)% or more, more preferably 40 mol% or more, particularly 50 mol% or more. The higher the specific diamine content ratio in the diamine component, the higher the effect of suppressing scratches on the alignment film surface and the film peeling during the rubbing treatment. Moreover, the solubility with respect to the organic solvent of the polyimide obtained also becomes high. On the other hand, the diamine component may be only the specific diamine, but it is preferable to use a diamine other than the specific diamine because other characteristics required for the liquid crystal alignment film can be imparted. Therefore, the content of the specific diamine is more preferably 90 mol% or less. In particular, when a specific diamine and 4-aminobenzylamine, 3-aminobenzylamine, or 4-aminophenethylamine are used, the solubility of polyimide in an organic solvent increases, and a liquid crystal alignment treatment agent with excellent liquid crystal alignment is obtained. This is particularly preferable. The preferred content of 4-aminobenzylamine, 3-aminobenzylamine, or 4-aminophenethylamine in the diamine component is 10 mol% to 50 mol%.

Also, in order to increase the pretilt angle of the liquid crystal, a diamine having a specific substituent can be used in combination. As the substituent capable of increasing the pretilt angle of the liquid crystal, a long-chain alkyl group, a perfluoroalkyl group, an aromatic cyclic group, an aliphatic cyclic group, a combination of these, or a steroid skeleton group is preferable. Although the specific example of the diamine which has the said substituent is given to the following, it is not limited to this. In the structures exemplified below, j represents an integer of 5 to 20, preferably 9 to 17, and k represents an integer of 1 to 20, preferably 4 to 15.

Among the above diamines, the diamines of the formulas [5] and [32] are preferable because of excellent liquid crystal alignment. The diamines represented by the formulas [12] to [19] have a very high tilting ability, and are therefore suitably used for OCB (Optically ｍｐ Compensated Bend) alignment films and VA (Vertical Alignment) alignment films. As a preferred example, in a TN (Twisted Nematic) alignment film (pretilt 3 to 5 °), the diamine of formula [5] or [32] is 5 to 40 mol%, preferably 10 to 30 mol in the diamine component. %, OCB, VA alignment film (pretilt 10-90 °), the diamine of formula [12]-[19] may be contained in the diamine component in an amount of 5-60 mol%, preferably 10-40 mol%. It is not limited to this.

Among the above diamines, the diamine of formula [32] is particularly preferable because it has a high tilt angle and is excellent in liquid crystal alignment even when the rubbing conditions are weak when used in combination with the specific diamine. . Furthermore, the effect of increasing the pretilt angle of the liquid crystal as described above tends to be weakened when the liquid crystal aligning agent contains a large amount of N-ethyl-2-pyrrolidone or N-cyclohexyl-2-pyrrolidone. However, the diamine of the formula [32] has a characteristic that it is not easily affected by the above, and is suitable as a diamine component of the polyimide contained in the liquid crystal aligning agent of the present invention.

[Tetracarboxylic dianhydride component]
In the present invention, the tetracarboxylic dianhydride component used as a raw material for polyimide may be one type of tetracarboxylic dianhydride or a mixture of two or more types of tetracarboxylic dianhydrides. good.
However, even if it is a polyimide with a high imidization rate, a tetracarboxylic acid having an alicyclic structure or an aliphatic structure can be obtained because it is easy to obtain a polyimide with relatively high solubility and the voltage holding ratio of the liquid crystal cell can be increased. It is preferable to use an acid dianhydride.

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-like dianhydride.

Examples of the tetracarboxylic dianhydride having an alicyclic structure or an aliphatic structure include 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 3,4-dicarboxy-1,2,3,4 Use of tetrahydro-1-naphthalene succinic dianhydride or 1,2,3,4-butanetetracarboxylic dianhydride is particularly preferable because an alignment film excellent in liquid crystal alignment can be obtained.

Furthermore, when an aromatic tetracarboxylic dianhydride is used in combination with a tetracarboxylic dianhydride having an alicyclic structure or an aliphatic structure, the liquid crystal alignment is improved and the accumulated charge of the liquid crystal cell is reduced. This is preferable. Aromatic tetracarboxylic dianhydrides include pyromellitic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2,2 ′, 3,3′-biphenyltetracarboxylic acid Dianhydride, 2,3,3 ′, 4-biphenyltetracarboxylic dianhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, 2,3,3 ′, 4-benzophenonetetra Carboxylic dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, bis (3,4-dicarboxyphenyl) sulfone dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride And 2,3,6,7-naphthalenetetracarboxylic dianhydride and the like.

Aromatic tetracarboxylic dianhydrides include, among others, pyromellitic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride Or 1,4,5,8-naphthalenetetracarboxylic dianhydride is particularly preferred.

Considering the balance of properties such as polyimide solubility, liquid crystal orientation, voltage holding ratio, accumulated charge, tetracarboxylic dianhydride having an alicyclic structure or aliphatic structure, and aromatic tetracarboxylic The ratio with the acid dianhydride is preferably 90/10 to 50/50, more preferably 80/20 to 60/40, as the molar ratio of the former / the latter.

[Polyimide and its production method]
The polyimide used for the liquid-crystal aligning agent of this invention is a polyimide which imidized the polyamic acid obtained by making the above-mentioned diamine component and the tetracarboxylic dianhydride component react. Here, the polyamic acid can be obtained by mixing and reacting a tetracarboxylic dianhydride component and a diamine component in an organic solvent.

As a method of mixing the tetracarboxylic dianhydride component and the diamine component in an organic solvent, a solution in which the diamine component is dispersed or dissolved in the organic solvent is stirred, and the tetracarboxylic dianhydride component is used as it is or in an organic solvent. A method of adding by dispersing or dissolving in a solvent, a method of adding a diamine component to a solution in which a tetracarboxylic dianhydride component is dispersed or dissolved in an organic solvent, and a tetracarboxylic dianhydride component and a diamine component. The method of adding alternately etc. are mentioned. When the tetracarboxylic dianhydride component or the diamine component is composed of a plurality of types of compounds, the plurality of types of components may be preliminarily mixed, or may be individually polymerized sequentially.

The temperature at which the tetracarboxylic dianhydride component and the diamine component are subjected to a polymerization reaction in an organic solvent is usually 0 to 150 ° C., preferably 5 to 100 ° C., more preferably 10 to 80 ° C. When the temperature is higher, the polymerization reaction is completed earlier, but when it is too high, a high molecular weight polymer may not be obtained.

The polymerization reaction can be carried out at any concentration, but if the concentration is too low, it will be difficult to obtain a high molecular weight polymer, and if the concentration is too high, the viscosity of the reaction solution will become too high and uniform stirring will occur. Since it becomes difficult, the concentration of the total amount of the tetracarboxylic dianhydride component and the diamine component is preferably 1 to 50% by mass, more preferably 5 to 30% by mass. The initial stage of the polymerization reaction may be performed at a high concentration, and then an organic solvent may be added.

The organic solvent used in the above reaction is not particularly limited as long as the generated polyamic acid can be dissolved, but N-ethyl-2-pyrrolidone or N-cyclohexyl-2 which is an essential component for the liquid crystal aligning agent. -Pyrrolidone or other solvents may be used. Specific examples thereof include N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methylcaprolactam, dimethyl sulfoxide, tetramethyl urea, pyridine, dimethyl sulfone, hexamethyl sulfoxide, γ-butyrolactone, 1,3-dimethylimidazolidinone and the like can be mentioned. These may be used alone or in combination. Furthermore, even if the solvent does not dissolve the polyamic acid, it may be used by mixing with the above solvent as long as the produced polyamic acid does not precipitate. In addition, since water in the organic solvent inhibits the polymerization reaction and further causes hydrolysis of the generated polyamic acid, it is preferable to use a dehydrated and dried organic solvent as much as possible.

The ratio of the tetracarboxylic dianhydride component and the diamine component used for the polymerization reaction of the polyamic acid is preferably 1: 0.8 to 1: 1.2 in molar ratio, and this molar ratio is close to 1: 1. The molecular weight of the polyamic acid obtained increases. By controlling the molecular weight of this polyamic acid, the molecular weight of the polyimide obtained after imidation can be adjusted.

The molecular weight of the polyimide contained in the liquid crystal aligning agent of the present invention is not particularly limited, but in terms of the strength of the coating film and the ease of handling as a liquid crystal aligning agent, the weight average molecular weight is 2,000 to 200, 000 is preferred, more preferably 5,000 to 50,000.
The imidization of the polyamic acid obtained as described above can be performed by stirring in an organic solvent for 1 to 100 hours in the presence of a basic catalyst and an acid anhydride.

Examples of basic catalysts include pyridine, triethylamine, trimethylamine, tributylamine, and trioctylamine. Of these, pyridine is preferable because 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 because the obtained polyimide can be easily purified after imidization. As an organic solvent, the solvent used at the time of the polyamic acid polymerization reaction mentioned above can be used.

The imidation ratio of polyimide can be controlled by adjusting the amount of catalyst, reaction temperature, and reaction time. The amount of the basic catalyst at this time is preferably 0.2 to 10 times mol, more preferably 0.5 to 5 times mol of the amic acid group of the starting polyamic acid. The amount of the acid anhydride is preferably 1 to 30 times mol, more preferably 1 to 10 times mol of the amic acid group of the starting polyamic acid. The reaction temperature is preferably −20 to 250 ° C., more preferably 0 to 180 ° C.

Although the imidation ratio of the polyimide contained in the liquid crystal aligning agent of the present invention is not particularly limited, it is preferably 40% or more in consideration of electrical characteristics, and 60% or more is more preferable in order to obtain a high voltage holding ratio. More preferably, it is 80% or more.
Since the added catalyst or the like remains in the polyimide solution thus obtained, it is preferable to use the liquid crystal alignment treatment agent of the present invention after recovering and washing the specific polyimide.

The polyimide can be recovered by putting the solution after imidization into a poor solvent that is being stirred and precipitating the polyimide, followed by filtration. Examples of the poor solvent at this time include methanol, acetone, hexane, butyl cellosolve, heptane, methyl ethyl ketone, methyl isobutyl ketone, ethanol, toluene, and benzene. The recovered polyimide can also be washed with this poor solvent.
The polyimide recovered and washed in this way can be powdered by drying at room temperature or under normal pressure or reduced pressure.

[Liquid crystal aligning agent]
The liquid crystal alignment treatment agent of the present invention is a solution containing the above polyimide as a resin component and N-ethyl-2-pyrrolidone or N-cyclohexyl-2-pyrrolidone as a solvent component. In the present invention, it is necessary to use N-ethyl-2-pyrrolidone or N-cyclohexyl-2-pyrrolidone as a solvent component. Even when a pyrrolidone compound is used, for example, when N-methyl-2-pyrrolidone is used. As shown in a comparative example described later, whitening of the coating film and unevenness of the film thickness in the vicinity of the printing edge may occur, and it is difficult to achieve the object of the present invention.

The concentration of the solution constituting the liquid crystal alignment treatment agent can be appropriately changed by setting the thickness of the liquid crystal alignment film to be formed. The solvent component is preferably 9 to 99 with respect to 1 part by mass of the nonvolatile component such as the resin component. Part by mass, more preferably 11.5 to 49 parts by mass. When the solvent component is more than 99 parts by mass, it is difficult to form a uniform and defect-free coating film, and when it is less than 9 parts by mass, the storage stability of the solution may be deteriorated. The content of the solvent component in the liquid crystal aligning agent of the present invention is preferably 90 to 99% by mass, more preferably 92 to 98 parts by mass with respect to the entire liquid crystal aligning agent.

The resin component in the liquid crystal aligning agent of the present invention may be a mixture of two or more types of polyimides having different structures. In addition, polyamic acid and other types of resins are used together to the extent that electrical properties are not impaired, storage stability of the varnish is not deteriorated, and aggregates that cause gap unevenness of the liquid crystal panel are not generated during printing. May be. The amount of the resin used in combination is preferably 0.05 to 7 parts by mass, more preferably 0.1 to 4 parts by mass with respect to 1 part by mass of polyimide. The content of the resin component in the liquid crystal aligning agent of the present invention is preferably 1 to 10% by mass, more preferably 2 to 8% by mass, based on the entire liquid crystal aligning agent.

The solvent component in the liquid crystal aligning agent of the present invention may be only N-ethyl-2-pyrrolidone, but contains other solvents in order to ensure the solubility of the resin component and to control the coating property to the substrate. It is preferable to do. On the other hand, in the case of N-cyclohexyl-2-pyrrolidone, since the solubility of polyimide is inferior to that of N-ethyl-2-pyrrolidone, its content is determined from the viewpoint of long-term storage stability of the liquid crystal aligning agent. It is preferable to contain a solvent for ensuring the solubility of the resin component as the other solvent component.

Solvents for ensuring the solubility of the resin component include N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methylcaprolactam, 2-pyrrolidone, N-vinylpyrrolidone, dimethyl Examples thereof include sulfoxide, tetramethylurea, dimethylsulfone, hexamethylsulfoxide, γ-butyrolactone, 1,3-dimethyl-imidazolidinone. Among these, N-methyl-2-pyrrolidone, 1,3-dimethylimidazolidinone, and γ-butyrolactone are preferably used because of the high solubility of polyimide. Γ-butyrolactone is preferably used because it has an effect of suppressing whitening.

Examples of the solvent for controlling the coating property to the substrate include a solvent having a low surface tension. By appropriately mixing a solvent having a low surface tension with the solvent component, the coating film uniformity can be improved during application to the substrate.

Solvents having low surface tension include ethyl cellosolve, butyl cellosolve, ethyl carbitol, butyl carbitol, ethyl carbitol acetate, ethylene glycol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, 1-butoxy- 2-propanol, 1-phenoxy-2-propanol, diethylene glycol diethyl ether, propylene glycol monoacetate, propylene glycol diacetate, dipropylene glycol monomethyl ether, propylene glycol-1-monomethyl ether-2-acetate, propylene glycol-1-mono Ethyl ether-2-acetate, dipropylene glycol, 2- (2-ethoxypropoxy) propanol, lactate methyl ester, ethyl lactate Le, lactate n- propyl ester, lactate n- butyl ester, and the like lactic isoamyl ester. Among these, butyl cellosolve, ethyl carbitol, dipropylene glycol monomethyl ether, or diethylene glycol diethyl ether is particularly preferable from the viewpoint of applicability to the substrate.

When the solvent component contains the above-mentioned other solvent, the amount of N-ethyl-2-pyrrolidone or N-cyclohexyl-2-pyrrolidone is 0.5 parts by mass or more with respect to 1 part by mass of the resin component The improvement effect which suppresses generation | occurrence | production of the aggregate is seen, Preferably it is 1 to 80 weight part, More preferably, it is 2 to 70 weight part. In particular, N-ethyl-2-pyrrolidone is preferably used because it has excellent solubility of the resin component and thus excellent storage stability of the varnish, and varnish is not easily whitened even when moisture is absorbed. In the present invention, N-ethyl-2-pyrrolidone is preferably 5 to 80% by mass, more preferably 10 to 70% by mass, based on the entire solvent component. On the other hand, N-cyclohexyl-2-pyrrolidone is preferably 5 to 40% by mass, more preferably 10 to 30% by mass, based on the entire solvent component. Further, as described above, from the viewpoint of not reducing the effect of the diamine that increases the pretilt angle of the liquid crystal, N-ethyl-2-pyrrolidone is preferably 40% by mass or less of the total solvent component.

In addition, the solvent for ensuring the solubility of the resin component, when the amount is too large, whitening of the varnish or generation of foreign matter during printing, the content is preferably 80% by mass or less of the solvent component, more preferably Is 60% by mass or less. A solvent having a low surface tension improves the coating property to the substrate, but if the amount is too large, precipitation of the resin component occurs, so the content is preferably 60% by mass or less, more preferably 50% by mass of the solvent component. It is as follows. When a solvent for ensuring the solubility of the resin component is used in combination with a solvent having a low surface tension, the more preferable content of each solvent is 5 to 70% by mass of the solvent for ensuring the solubility of the resin component. The solvent having a low surface tension is 10 to 60% by mass, more preferably the solvent for ensuring the solubility of the resin component is 10 to 45% by mass, and the solvent having a low surface tension is 20 to 50% by mass. %.

Examples of the solvent composition in the liquid crystal aligning agent of the present invention include 5 to 80% by mass of N-ethyl-2-pyrrolidone, 5 to 70% by mass of a solvent for ensuring the solubility of the resin component, and a low surface. Mixed solvent with 10-60 mass% of solvent having tension; 10-70 mass% of N-ethyl-2-pyrrolidone, 10-45 mass% of solvent for ensuring the solubility of the resin component, low surface tension Mixed solvent having a solvent of 20 to 50% by mass; 5 to 40% by mass of N-ethyl-2-pyrrolidone, 5 to 70% by mass of a solvent for ensuring the solubility of the resin component, and 10 of a solvent having a low surface tension Mixed solvent of ˜60% by mass; N-ethyl-2-pyrrolidone is 10 to 40% by mass, the solvent for ensuring the solubility of the resin component is 10 to 45% by mass, and the solvent having a low surface tension is 20 to 50% by mass. % Mixed solvent; N-cyclohexyl -2-pyrrolidone in a mixed solvent of 5 to 40% by mass, a solvent for ensuring the solubility of the resin component in a range of 5 to 70% by mass, and a solvent having a low surface tension of 10 to 60% by mass; N-cyclohexyl-2- Examples thereof include a mixed solvent of 10 to 40% by mass of pyrrolidone, 10 to 45% by mass of a solvent for ensuring the solubility of the resin component, and 20 to 50% by mass of a solvent having a low surface tension.
In addition to the above, the liquid crystal aligning agent of the present invention may contain additives for improving the properties of the coating film.

Additives for improving coating properties include 3-aminopropylmethyldiethoxysilane, 3-phenylaminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, (aminoethylaminomethyl) phenethyltrimethoxysilane And silane coupling agents such as The addition of these silane coupling agents can further improve the adhesion of the coating film to the substrate, but if added too much, the polyimide used in the present invention and the polymer compound used in combination with it will cause aggregation. Therefore, the content of the silane coupling agent is preferably 0.1 to 20 parts by mass, more preferably 0.2 to 10 parts by mass with respect to 100 parts by mass of the resin component used in the present invention.

[Method for Preparing Liquid Crystal Alignment Treatment Agent]
The method for preparing the liquid crystal aligning agent of the present invention is not particularly limited as long as the contained components are in a uniform state in the liquid crystal aligning agent. For example, a polyimide powder is dissolved in an organic solvent to form a polyimide solution, and then diluted by adding an organic solvent to a desired concentration. In this dilution step, adjustment of the solvent composition for controlling the coating property to the substrate, addition of an additive for improving the properties of the coating film, and the like can be performed. Examples of the solvent for dissolving the polyimide powder include N-ethyl-2-pyrrolidone, N-cyclohexyl-2-pyrrolidone, and the solvents described above. The liquid crystal aligning agent obtained as described above is preferably filtered before being applied to the substrate.

The liquid crystal alignment treatment agent of the present invention can be applied to a substrate, dried and baked to form a coating film. By rubbing this coating film surface, it is used as a liquid crystal alignment film for rubbing. It is also used as a liquid crystal alignment film for VA or a photo alignment film that is not rubbed.

At this time, the substrate to be used is not particularly limited as long as it is a highly transparent substrate, and a glass substrate, a plastic substrate such as an acrylic substrate or a polycarbonate substrate can be used, and an ITO electrode for driving a liquid crystal is formed. It is preferable to use a new substrate from the viewpoint of simplification of the process. Further, in the reflection type liquid crystal display element, an opaque material such as a silicon wafer can be used as long as the substrate is only on one side, and in this case, a material that reflects light such as aluminum can be used.

Examples of the method for applying the liquid crystal aligning agent include spin coating, printing, and ink-jet methods. From the viewpoint of productivity, the flexographic printing method is widely used industrially, and the liquid crystal aligning treatment of the present invention. It is also preferably used in agents.

The drying process after applying the liquid crystal alignment treatment 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, the drying process is performed. Inclusion 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 the conveyance of the substrate or the like. As a specific example, 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 is employed.

The substrate coated with the liquid crystal aligning agent can be baked at an arbitrary temperature of 100 to 350 ° C., preferably 150 to 300 ° C., more preferably 180 to 250 ° C. When an amic acid group is present in the liquid crystal aligning agent, it changes from an amic acid to an imide depending on the baking temperature, but the liquid crystal aligning agent of the present invention does not necessarily need to be 100% imidized.

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 that 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.

The liquid crystal display element of the present invention is a liquid crystal display element obtained by obtaining a substrate with a liquid crystal alignment film from the liquid crystal aligning agent of the present invention by the method described above, and then preparing a liquid crystal cell by a known method. As an example of manufacturing a liquid crystal cell, an alignment treatment direction is 0 to 270 ° with a pair of substrates on which a liquid crystal alignment film is formed, preferably with a spacer of 1 to 30 μm, more preferably 2 to 10 μm. A method is generally used in which the angle is set at an arbitrary angle, the periphery is fixed with a sealant, and liquid crystal is injected and sealed. The method for enclosing the liquid crystal is not particularly limited, and examples thereof include a vacuum method of injecting liquid crystal after reducing the pressure inside the produced liquid crystal cell, and a dropping method of sealing after dropping the liquid crystal.

The liquid crystal display elements thus obtained include various types such as TN liquid crystal display elements, STN liquid crystal display elements, TFT liquid crystal display elements, OCB liquid crystal display elements, lateral electric field type liquid crystal display elements, and VA liquid crystal display elements. It is suitably used for a display element by the above method.

The present invention will be described in more detail with reference to the following examples, but the present invention should not be construed as being limited thereto.
Abbreviations used in Examples and Comparative Examples are as follows.

<Tetracarboxylic dianhydride>
CBDA: 1,2,3,4-cyclobutanetetracarboxylic dianhydride PMDA: pyromellitic dianhydride TDA: 3,4-dicarboxy-1,2,3,4-tetrahydro-1-naphthalene-2-succinic acid Anhydride <Diamine>
2,4-DAA: 2,4-Diamino-N, N-diallylaniline

p-PDA: p-phenylenediamine DDM: 4,4′-diaminodiphenylmethane BAPP: 1,5-bis (4-aminophenoxy) pentane C12DAB: 4-dodecyloxy-1,3-diaminobenzene C14DAB: 4-tetradecyl Oxy-1,3-diaminobenzene C18DAB: 4-octadecyloxy-1,3-diaminobenzene PCBA-PDA: 4- (t-4-pentylcyclohexyl) benzamide-2 ′, 4′-phenylenediamine

3-ABA: 3-Aminobenzylamine

<Organic solvent>
NMP: N-methyl-2-pyrrolidone NEP: N-ethyl-2-pyrrolidone NCP: N-cyclohexyl-2-pyrrolidone γBL: γ-butyrolactone DMI: 1,3-dimethylimidazolidinone BC: Butyl cellosolve DPM: Dipropylene glycol Monomethyl ether EC: Ethyl carbitol

<Measurement of molecular weight>
The molecular weight of the polyimide was measured with a GPC (normal temperature gel permeation chromatography) apparatus, and the number average molecular weight and weight average molecular weight were calculated 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, phosphoric acid / anhydrous crystal (o-phosphoric acid) is 30 mmol / L, tetrahydrofuran (THF) is 10ml / L)
Flow rate: 1.0 ml / min Standard sample for preparing a calibration curve: TSK standard polyethylene oxide (weight average molecular weight: about 900,000, 150,000, 100,000, 30,000) manufactured by Tosoh Corporation and polyethylene glycol (weight average molecular weight: about 12,000, manufactured by Polymer Laboratories) 4,000, 1,000).

<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% TMS mixture) was added and completely dissolved. This solution was measured for proton NMR at 500 MHz with an NMR measuring instrument (JNM-ECA500) manufactured by JEOL Datum. The imidation rate is determined by determining a proton derived from a structure that does not change before and after imidation as a reference proton, a peak integrated value of this proton, and a proton peak integrated value derived from the NH group of the amic acid that appears around 9.5 to 10.0 ppm. Was obtained by the following equation.
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.

(Synthesis Example 1)
As a tetracarboxylic dianhydride component, 13.53 g (0.069 mol) of CBDA, 6.54 g (0.030 mol) of PMDA, and 6.10 g (0.030 mol) of 2,4-DAA as a diamine component, Using 3.89 g (0.040 mol) of 3-ABA and 9.62 g (0.030 mol) of C14DAB, the reaction was performed in NMP162.7 g at 23 ° C. for 24 hours to obtain a polyamic acid solution.
331.8 g of NMP was added to 142.8 g of this polyamic acid solution for dilution, 21.5 g of acetic anhydride and 9.2 g of pyridine were added, and the mixture was reacted at a temperature of 50 ° C. for 3 hours to imidize.
The reaction solution was cooled to about room temperature and then poured into 1.8 l of methanol to recover the precipitated solid. The solid was washed several times with methanol and then dried under reduced pressure at a temperature of 100 ° C. to obtain a white powder of polyimide (SPI). The number average molecular weight of this polyimide was 13,472, and the weight average molecular weight was 35,859. Further, the imidization ratio was 89%.

(Synthesis Example 2)
131.3 g of γBL was added to 17.9 g of polyimide obtained in the same manner as in Synthesis Example 1, and the mixture was stirred at a temperature of 50 ° C. for 24 hours. The polyimide was completely dissolved at the end of stirring.
(Synthesis Example 3)
14.4 g of NEP was added to 1.6 g of polyimide obtained in the same manner as in Synthesis Example 1, and the mixture was stirred at a temperature of 50 ° C. for 24 hours. The polyimide was completely dissolved at the end of stirring.
(Synthesis Example 4)
14.4 g of NMP was added to 1.6 g of the polyimide obtained in Synthesis Example 1, and the mixture was stirred at a temperature of 50 ° C. for 24 hours. The polyimide was completely dissolved at the end of stirring.
(Synthesis Example 5)
To 1.6 g of the polyimide obtained in Synthesis Example 1, 8 g of γBL and 6.4 g of NCP were added and stirred at a temperature of 50 ° C. for 24 hours. The polyimide was completely dissolved at the end of stirring.

(Synthesis Example 6)
As a tetracarboxylic dianhydride component, 13.53 g (0.069 mol) of CBDA, 6.54 g (0.030 mol) of PMDA, and 7.12 g (0.035 mol) of 2,4-DAA as a diamine component, Using 3.89 g (0.040 mol) of 3-ABA and 10.19 g (0.025 mol) of PCBA-PDA, the reaction was carried out in NMP 169.1 g at 23 ° C. for 24 hours to obtain a polyamic acid solution.
To 150 g of this polyamic acid solution, 350 g of NMP was added for dilution, 21.74 g of acetic anhydride and 9.27 g of pyridine were added, and the mixture was reacted at 50 ° C. for 3 hours to imidize.
The reaction solution was cooled to about room temperature and then poured into 1.86 l of methanol to recover the precipitated solid. The solid was washed several times with methanol and then dried under reduced pressure at a temperature of 100 ° C. to obtain a white powder of polyimide (SPI). The number average molecular weight of this polyimide was 12,156, and the weight average molecular weight was 32,418. Moreover, the imidation ratio was 90%.

(Synthesis Example 7)
35.2 g of γBL was added to 4.8 g of polyimide obtained in the same manner as in Synthesis Example 6, and the mixture was stirred at a temperature of 50 ° C. for 24 hours. The polyimide was completely dissolved at the end of stirring.
(Synthesis Example 8)
As the tetracarboxylic dianhydride component, 15.1 g (0.05 mol) of TDA, 4.87 g (0.045 mol) of p-PDA and 1.88 g (0.005 mol) of C18DAB were used as the diamine component, and NMP The reaction was carried out in 123.3 g at 50 ° C. for 24 hours to obtain a polyamic acid solution.
To this polyamic acid solution, 350 g of NMP was added for dilution, 51.0 g of acetic anhydride and 23.7 g of pyridine were added, and the mixture was reacted at a temperature of 40 ° C. for 3 hours to imidize.
The reaction solution was cooled to about room temperature and then poured into 1.7 l of methanol, and the precipitated solid was recovered. The solid was washed several times with methanol and then dried under reduced pressure at a temperature of 100 ° C. to obtain a white powder of polyimide (SPI). The number average molecular weight of this polyimide was 9,273, and the weight average molecular weight was 18,815. Moreover, the imidation ratio was 84%.

(Synthesis Example 9)
94.0 g of NEP was added to 6.0 g of polyimide obtained in the same manner as in Synthesis Example 8, and the mixture was stirred at a temperature of 50 ° C. for 24 hours. The polyimide was completely dissolved at the end of stirring.
(Synthesis Example 10)
As the tetracarboxylic dianhydride component, 4.90 g (0.025 mol) of CBDA, 4.80 g (0.022 mol) of PMDA, and 9.91 g (0.05 mol) of DDM as the diamine component were used, and 55.5 g of NEP was used. In a mixed solvent of γBL55.5 g, a reaction was performed at room temperature for 5 hours to obtain a polyamic acid solution. The number average molecular weight of this polyamic acid was 11,067, and the weight average molecular weight was 26,270.
(Synthesis Example 11)
NEP and BC were added to 50 g of the polyamic acid solution obtained in Synthesis Example 10 to prepare 6% by mass of polyamic acid, 59% by mass of NEP, 20% by mass of γ-BL, and 15% by mass of BC.

(Synthesis Example 12)
As a tetracarboxylic dianhydride component, 15.01 g (0.05 mol) of TDA, 2.70 g (0.025 mol) of p-PDA as a diamine component, and 3.05 g (0.015 mol) of 2,4-DAA ), 4.08 g (0.01 mol) of PCBA-PDA was used and reacted in 140.8 g of NMP at 50 ° C. for 24 hours to obtain a polyamic acid solution.
To this polyamic acid solution, 331 g of NMP was added for dilution, 51.0 g of acetic anhydride and 23.7 g of pyridine were added, and the mixture was reacted at a temperature of 40 ° C. for 3 hours to imidize.
The reaction solution was cooled to about room temperature and then poured into 2.0 l of methanol to recover the precipitated solid. The solid was washed several times with methanol and then dried under reduced pressure at a temperature of 100 ° C. to obtain a white powder of polyimide (SPI). The number average molecular weight of this polyimide was 8,579, and the weight average molecular weight was 22,319. The imidation ratio was 87%.

(Synthesis Example 13)
94.0 g of γBL was added to 6.0 g of polyimide obtained in the same manner as in Synthesis Example 12, and the mixture was stirred at a temperature of 50 ° C. for 24 hours. The polyimide was completely dissolved at the end of stirring.
(Synthesis Example 14)
ΓBL and BC were added to 50 g of the polyamic acid solution obtained in Synthesis Example 10 to prepare 6% by mass of polyamic acid, 59% by mass of γBL, 20% by mass of NEP, and 15% by mass of BC.
(Synthesis Example 15)
As the tetracarboxylic dianhydride component, 19.41 g (0.099 mol) of CBDA, as the diamine component, 5.73 g (0.02 mol) of BAPP, 14.23 g (0.07 mol) of 2,4-DAA, Using 4.08 g (0.01 mol) of PCBA-PDA, the reaction was carried out in 236.2 g of NMP at 23 ° C. for 24 hours to obtain a polyamic acid solution.
To this polyamic acid solution, 434 g of NMP was added for dilution, 25.8 g of acetic anhydride and 11.0 g of pyridine were added, and the mixture was reacted at a temperature of 35 ° C. for 3 hours to imidize.
The reaction solution was cooled to about room temperature and then poured into 2.7 l of methanol to recover the precipitated solid. The solid was washed several times with methanol and then dried under reduced pressure at a temperature of 100 ° C. to obtain a white powder of polyimide (SPI). The number average molecular weight of this polyimide was 12,132, and the weight average molecular weight was 26,538. Moreover, the imidation ratio was 70%.

(Synthesis Example 16)
108.0 g of NEP was added to 12.0 g of polyimide obtained in the same manner as in Synthesis Example 15, and the mixture was stirred at a temperature of 50 ° C. for 24 hours. The polyimide was completely dissolved at the end of stirring.
(Synthesis Example 17)
As the tetracarboxylic dianhydride component, 19.41 g (0.099 mol) of CBDA, 14.23 g (0.07 mol) of 2,4-DAA and 8.77 g (0.03 mol) of C12DAB were used as the diamine component. , NMP (169.7 g) was reacted at 23 ° C. for 24 hours to obtain a polyamic acid solution.
To this polyamic acid solution, 494.9 g of NMP was added for dilution, 30.6 g of acetic anhydride and 13.1 g of pyridine were added, and the mixture was reacted at a temperature of 50 ° C. for 3 hours to imidize.
The reaction solution was cooled to about room temperature and then poured into 2.6 l of methanol to recover the precipitated solid. The solid was washed several times with methanol and then dried under reduced pressure at a temperature of 100 ° C. to obtain a white powder of polyimide (SPI). The number average molecular weight of this polyimide was 11,098, and the weight average molecular weight was 21,431. Moreover, the imidation ratio was 91%.
(Synthesis Example 18)
14.4 g of NEP was added to 1.6 g of polyimide obtained in the same manner as in Synthesis Example 17, and the mixture was stirred at a temperature of 50 ° C. for 24 hours. The polyimide was completely dissolved at the end of stirring.

(Example 1)
After cooling 20.23 g of the solution obtained in the same manner as in Synthesis Example 2 to 23 ° C., 8.67 g of γBL, 4.93 g of NEP and 14.78 g of BC were added, and the mixture was stirred at a temperature of 50 ° C. for 20 hours. After stirring, the mixture was cooled to 23 ° C. to obtain a uniform liquid crystal aligning agent. Table 1 shows the composition of the obtained liquid crystal aligning agent.

<Evaluation of voltage holding ratio>
About the said liquid-crystal aligning agent, the voltage holding rate of the liquid crystal cell was evaluated as follows.
A liquid crystal alignment treatment agent is spin-coated on a glass substrate with a transparent electrode, dried on a hot plate at a temperature of 70 ° C. for 70 seconds, and then baked on a hot plate at 210 ° C. for 10 minutes to form a coating film having a thickness of 100 nm. I let you. The surface of the coating film was rubbed with a rubbing apparatus having a roll diameter of 120 mm using a rayon cloth under the conditions of a roll rotation speed of 1000 rpm, a roll traveling speed of 50 mm / sec, and an indentation amount of 0.3 mm to obtain a substrate with a liquid crystal alignment film.
Prepare two sheets of this substrate, spray a 6μm spacer on the surface of one liquid crystal alignment film, print a sealant on it, and the other substrate faces the liquid crystal alignment film and the rubbing direction is perpendicular. After the lamination, the sealing agent was cured to produce an empty cell. Liquid crystal MLC-2003 (manufactured by Merck Japan) was injected into this empty cell by a reduced pressure injection method, and the injection port was sealed to obtain a twisted nematic liquid crystal cell.
A voltage of 4 V was applied to the liquid crystal cell at a temperature of 90 ° C. for 60 μs, the voltage after 16.67 ms was measured, and how much the voltage could be held was calculated as a voltage holding ratio. The voltage holding ratio was measured using a VHR-1 voltage holding ratio measuring device manufactured by Toyo Technica. The evaluation results are shown in Table 2.

<Measurement of tilt angle>
Using the liquid crystal cell obtained in the same manner as in the above <Production of liquid crystal cell>, the tilt angle of the liquid crystal was measured. For the measurement, TBA107 manufactured by Autronic was used. The measurement was performed before heating (23 ° C.) and under the condition that the liquid crystal cell was held at 60 ° C. The results are shown in Table 3.

<Evaluation of liquid crystal alignment in weak rubbing>
In the above <Evaluation of voltage holding ratio>, the liquid crystal cell was created under the same conditions except that the rubbing roller push-in was changed to 0.2 mm and the substrates were bonded so that the rubbing direction was 180 ° (anti-parallel). did. At that time, after liquid crystal injection, the presence / absence of liquid crystal orientation was observed from the injection port of the liquid crystal cell, and the following evaluation was performed.
○: Flow orientation is not observed.
Δ: Slight flow orientation is observed.
X: Many streaky flow orientations are observed.
The evaluation results are shown in Table 3.

<Evaluation of rubbing resistance>
In the above <Evaluation of voltage holding ratio>, rubbing was performed under the condition that the indentation of the rubbing roller was changed to 0.5 mm, and a substrate with a liquid crystal alignment film was prepared. The surface of the liquid crystal alignment film was observed with a laser microscope, and the following evaluation was performed visually.
○: Scraping and rubbing scratches hardly occur.
X: Waste or rubbing scratches are generated.
The evaluation results are shown in Table 3.

<Evaluation of drying speed>
It spin-coated so that it might become a film thickness of 100 nm on the glass substrate (henceforth Cr board | substrate) which vapor-deposited said liquid crystal aligning agent (it abbreviate | omitted Cr board | substrate) (size 10cm x 10cm). Thereafter, at a temperature of 23 ° C. and a humidity of 45%, the time from when the spin coating was completed until the film was uniformly dried was measured. The result was 340 seconds.

<Evaluation of whitening characteristics>
About 0.1 ml of each liquid crystal alignment treatment agent was dropped on the Cr substrate and left in an environment at a temperature of 23 ° C. and a humidity of 45%. The vicinity of the end and the center of the droplet were observed with a microscope every hour. The observation was performed at a magnification of 100 times near the edge of the droplet and at a magnification of 50 times near the center of the droplet. The case where aggregates were observed near the edge and center of the droplet within 6 hours was evaluated as x, and the case where the aggregates were not observed after 6 hours was evaluated as ◯. The results are shown in Table 2.

<Evaluation of uneven printing>
Flexographic printing was performed on a Cr substrate washed with the above liquid crystal alignment treatment agent using an alignment film printer (“Angstromer” manufactured by Nissha Printing Co., Ltd.) (tact time 30 seconds). First, after performing the idling operation 10 times, printing was started, and the 10th printed board was used for observation. The substrate after printing was allowed to stand on a hot plate at 80 ° C. for 5 minutes, and the coating film was temporarily dried. The vicinity of the printing edge after the temporary drying was observed with an optical microscope ("ECLIPSE ME600" manufactured by Nikon Corporation) at a magnification of 50 times. The results are shown in Table 2.

<Foreign matter evaluation during printing>
Printing was performed using the same apparatus as described above. After performing the idling 10 times, the printing machine was stopped for 1 minute and the printing plate was dried. Thereafter, one Cr substrate was printed and fired in the same manner as described above. The fired substrate was observed in the vicinity of the printing edge with a confocal laser microscope ("VL2000" manufactured by Lasertec Co., Ltd.). If there was no foreign material of 3 µm or less near the printing edge, ○, did. The results are shown in Table 2.

<Evaluation of storage stability>
The liquid crystal aligning agent was stored at −20 ° C. for 2 months, and “O” indicates that there is no precipitation and varnish white turbidity, and “X” indicates that there is precipitation and varnish white turbidity.

(Example 2)
After cooling 21.00 g of the solution obtained in the same manner as in Synthesis Example 2 to 23 ° C., 3.87 g of γBL, 10.21 g of NEP and 15.32 g of BC were added, and the mixture was stirred at a temperature of 50 ° C. for 20 hours. After stirring, the mixture was cooled to 23 ° C. to obtain a uniform liquid crystal aligning agent. The composition of the obtained liquid crystal aligning agent is summarized in Table 1.
Using this liquid crystal alignment treatment agent, the voltage holding ratio, tilt angle, liquid crystal alignment property, rubbing resistance, drying speed, whitening characteristics, printing unevenness, foreign matter during printing, and storage stability were evaluated in the same manner as in Example 1. . The results are shown in Tables 2 and 3.

(Example 3)
After cooling 18.77 g of the solution obtained in the same manner as in Synthesis Example 2 to 23 ° C., 7.08 g of γBL, 4.80 g of NCP and 14.40 g of BC were added, and the mixture was stirred at a temperature of 50 ° C. for 20 hours. After stirring, the mixture was cooled to 23 ° C. to obtain a uniform liquid crystal aligning agent. The composition of the obtained liquid crystal aligning agent is summarized in Table 1.
Using this liquid crystal alignment treatment agent, the voltage holding ratio, tilt angle, liquid crystal alignment property, rubbing resistance, drying speed, whitening characteristics, printing unevenness, foreign matter during printing, and storage stability were evaluated in the same manner as in Example 1. . The results are shown in Tables 2 and 3.

Example 4
After cooling 19.49 g of the solution obtained in the same manner as in Synthesis Example 2 to 23 ° C., 3.28 g of γBL, 9.60 g of NCP and 14.40 g of BC were added, and the mixture was stirred at a temperature of 50 ° C. for 20 hours. After stirring, the mixture was cooled to 23 ° C. to obtain a uniform liquid crystal aligning agent. Table 1 shows the composition of the obtained liquid crystal aligning agent.
Using this liquid crystal alignment treatment agent, the voltage holding ratio, tilt angle, liquid crystal alignment property, rubbing resistance, drying speed, whitening characteristics, printing unevenness, foreign matter during printing, and storage stability were evaluated in the same manner as in Example 1. . The results are shown in Tables 2 and 3.

(Example 5)
After cooling the solution obtained in the same manner as in Synthesis Example 3 to about room temperature, 2.66 g of NEP and 8.00 g of BC were added, and the mixture was stirred at a temperature of 50 ° C. for 20 hours. After stirring, the mixture was cooled to 23 ° C. to obtain a uniform liquid crystal aligning agent. Table 1 shows the composition of the obtained liquid crystal aligning agent.
Using this liquid crystal alignment treatment agent, the voltage holding ratio, tilt angle, liquid crystal alignment property, rubbing resistance, drying speed, whitening characteristics, printing unevenness, foreign matter during printing, and storage stability were evaluated in the same manner as in Example 1. . The results are shown in Tables 2 and 3.

(Example 6)
After cooling 20 g of the solution obtained in the same manner as in Synthesis Example 7 to about room temperature, 8.8 g of γBL, 4.8 g of NEP, and 14.4 g of BC were added, and the mixture was stirred at a temperature of 50 ° C. for 20 hours. After stirring, the mixture was cooled to 23 ° C. to obtain a uniform liquid crystal aligning agent. Table 1 shows the composition of the obtained liquid crystal aligning agent.
Using this liquid crystal alignment treatment agent, the voltage holding ratio, tilt angle, liquid crystal alignment property, rubbing resistance, drying speed, whitening characteristics, printing unevenness, foreign matter during printing, and storage stability were evaluated in the same manner as in Example 1. . The results are shown in Tables 2 and 3.

(Example 7)
After cooling 20 g of the solution obtained in the same manner as in Synthesis Example 7 to about room temperature, 4.0 g of γBL, 14.4 g of NEP, and 9.6 g of BC were added, and the mixture was stirred at a temperature of 50 ° C. for 20 hours. After stirring, the mixture was cooled to 23 ° C. to obtain a uniform liquid crystal aligning agent. Table 1 shows the composition of the obtained liquid crystal aligning agent.
Using this liquid crystal alignment treatment agent, the voltage holding ratio, tilt angle, liquid crystal alignment property, rubbing resistance, drying speed, whitening characteristics, printing unevenness, foreign matter during printing, and storage stability were evaluated in the same manner as in Example 1. . The results are shown in Tables 2 and 3.

(Example 8)
20 g of the solution obtained in Synthesis Example 9 and 80 g of the solution obtained in Synthesis Example 11 were stirred at 23 ° C. for 20 hours. After the stirring, a uniform liquid crystal aligning agent was obtained. Table 1 shows the composition of the obtained liquid crystal aligning agent.
Using this liquid crystal alignment treatment agent, the voltage holding ratio, tilt angle, liquid crystal alignment property, rubbing resistance, drying speed, whitening characteristics, printing unevenness, foreign matter during printing, and storage stability were evaluated in the same manner as in Example 1. . The results are shown in Tables 2 and 3.

Example 9
20 g of the solution obtained in Synthesis Example 13 and 80 g of the solution obtained in Synthesis Example 14 were stirred at 23 ° C. for 20 hours. After the stirring, a uniform liquid crystal aligning agent was obtained. Table 1 shows the composition of the obtained liquid crystal aligning agent.
Using this liquid crystal alignment treatment agent, the voltage holding ratio, tilt angle, liquid crystal alignment property, rubbing resistance, drying speed, whitening characteristics, printing unevenness, foreign matter during printing, and storage stability were evaluated in the same manner as in Example 1. . The results are shown in Tables 2 and 3.

(Example 10)
60 g of the solution obtained in the same manner as in Synthesis Example 16 was cooled to about room temperature, 20 g of DMI and 20 g of EC were added, and the mixture was stirred at a temperature of 50 ° C. for 20 hours. After stirring, the mixture was cooled to 23 ° C. to obtain a uniform liquid crystal aligning agent. Table 1 shows the composition of the obtained liquid crystal aligning agent.
Using this liquid crystal alignment treatment agent, the voltage holding ratio, tilt angle, liquid crystal alignment property, rubbing resistance, drying speed, whitening characteristics, printing unevenness, foreign matter during printing, and storage stability were evaluated in the same manner as in Example 1. . The results are shown in Tables 2 and 3.

(Example 11)
60 g of the solution obtained in the same manner as in Synthesis Example 16 was cooled to about room temperature, 10 g of NMP and 30 g of BC were added, and the mixture was stirred at a temperature of 50 ° C. for 20 hours. After stirring, the mixture was cooled to 23 ° C. to obtain a uniform liquid crystal aligning agent. Table 1 shows the composition of the obtained liquid crystal aligning agent.
Using this liquid crystal alignment treatment agent, the voltage holding ratio, tilt angle, liquid crystal alignment property, rubbing resistance, drying speed, whitening characteristics, printing unevenness, foreign matter during printing, and storage stability were evaluated in the same manner as in Example 1. . The results are shown in Tables 2 and 3.

Example 12
The solution obtained in the same manner as in Synthesis Example 18 was cooled to about room temperature, 2.66 g of NEP and 8.00 g of BC were added, and the mixture was stirred at a temperature of 50 ° C. for 20 hours. After stirring, the mixture was cooled to 23 ° C. to obtain a uniform liquid crystal aligning agent. Table 1 shows the composition of the obtained liquid crystal aligning agent.
Using this liquid crystal alignment treatment agent, the voltage holding ratio, tilt angle, liquid crystal alignment property, rubbing resistance, drying speed, whitening characteristics, printing unevenness, foreign matter during printing, and storage stability were evaluated in the same manner as in Example 1. . The results are shown in Tables 2 and 3.

(Comparative Example 1)
After cooling the solution obtained in the same manner as in Synthesis Example 4 to 23 ° C., 2.66 g of NMP and 8.00 g of BC were added and stirred at a temperature of 50 ° C. for 20 hours. After stirring, the mixture was cooled to 23 ° C. to obtain a uniform liquid crystal aligning agent. The composition of the obtained liquid crystal aligning agent is summarized in Table 1.
Using this liquid crystal alignment treatment agent, the voltage holding ratio, tilt angle, liquid crystal alignment property, rubbing resistance, drying speed, whitening characteristics, printing unevenness, foreign matter during printing, and storage stability were evaluated in the same manner as in Example 1. . The results are shown in Tables 2 and 3. No foreign matter was observed, but whitening and film thickness unevenness were observed.

(Comparative Example 2)
After cooling 19.49 g of the solution obtained in the same manner as in Synthesis Example 2 to 23 ° C., 3.28 g of γBL, 9.60 g of NMP and 14.40 g of BC were added, and the mixture was stirred at a temperature of 50 ° C. for 20 hours. After stirring, the mixture was cooled to 23 ° C. to obtain a uniform liquid crystal aligning agent. Table 1 shows the composition of the obtained liquid crystal aligning agent.
Using this liquid crystal alignment treatment agent, the voltage holding ratio, tilt angle, liquid crystal alignment property, rubbing resistance, drying speed, whitening characteristics, printing unevenness, foreign matter during printing, and storage stability were evaluated in the same manner as in Example 1. . The results are shown in Tables 2 and 3. Although the whitening characteristics were good and no foreign matter was observed, film thickness unevenness was observed.

(Comparative Example 3)
After cooling 19.49 g of the solution obtained in the same manner as in Synthesis Example 2 to 23 ° C., 9.03 g of γBL, 9.13 g of BC and 9.13 g of DPM were added, and the mixture was stirred at a temperature of 50 ° C. for 20 hours. After stirring, the mixture was cooled to 23 ° C. to obtain a uniform liquid crystal aligning agent. Table 1 shows the composition of the obtained liquid crystal aligning agent.
Using this liquid crystal alignment treatment agent, the voltage holding ratio, tilt angle, liquid crystal alignment, rubbing resistance, drying speed, whitening characteristics, printing unevenness, foreign matter during printing, and storage stability were evaluated in the same manner as in Example 1. . The results are shown in Tables 2 and 3. Although the whitening characteristics were good, film thickness unevenness occurred and foreign matter was also observed.

(Example 13)
The solution obtained in the same manner as in Synthesis Example 5 was cooled to about room temperature, 6.40 g of NCP and 9.60 g of BC were added, and the mixture was stirred at a temperature of 50 ° C. for 20 hours. After stirring, the mixture was cooled to 23 ° C. to obtain a uniform liquid crystal aligning agent. Table 1 shows the composition of the obtained liquid crystal aligning agent.
Using this liquid crystal alignment treatment agent, the voltage holding ratio, tilt angle, liquid crystal alignment property, rubbing resistance, drying speed, whitening characteristics, printing unevenness, foreign matter during printing, and storage stability were evaluated in the same manner as in Example 1. . The results are shown in Tables 2 and 3.

Since the liquid crystal aligning agent of the present invention has good voltage holding characteristics and does not generate aggregates that cause gap unevenness of the liquid crystal panel during printing, a narrow gap liquid crystal panel can be produced with high yield. Therefore, the liquid crystal display element produced using the liquid crystal aligning agent of the present invention can be a highly reliable liquid crystal display device, such as a TN liquid crystal display element, an STN liquid crystal display element, a TFT liquid crystal display element, and an OCB liquid crystal display. It is suitably used for display elements of various systems such as elements, horizontal electric field type liquid crystal display elements, VA liquid crystal display elements.
It should be noted that the entire contents of the specification, claims, and abstract of Japanese Patent Application No. 2008-146792 filed on June 4, 2008 are incorporated herein as the disclosure of the specification of the present invention. Is.

Claims

A pyrrolidone compound comprising a resin component containing a polyimide obtained by imidizing a polyamic acid obtained by reacting a diamine component with tetracarboxylic dianhydride, and N-ethyl-2-pyrrolidone or N-cyclohexyl-2-pyrrolidone And a solvent component comprising: a liquid crystal aligning agent characterized by comprising:
The liquid crystal aligning agent according to claim 1, wherein the pyrrolidone compound is N-ethyl-2-pyrrolidone, and the N-ethyl-2-pyrrolidone is 5 to 80% by mass of the solvent component.
The liquid crystal aligning agent according to claim 1, wherein the pyrrolidone compound is N-cyclohexyl-2-pyrrolidone, and the N-cyclohexyl-2-pyrrolidone is 5 to 40% by mass of the solvent component.
4. The liquid crystal aligning agent according to claim 1, wherein the resin component is contained in an amount of 1 to 10% by mass and the solvent component is contained in an amount of 90 to 99% by mass.
5. The liquid crystal aligning agent according to claim 1, wherein the diamine component is diaminobenzene having a disubstituted amino group substituted with an alkenyl group having 2 or 3 carbon atoms.
The liquid crystal aligning agent of Claim 5 whose diaminobenzene which has a disubstituted amino group substituted by the C2-C3 alkenyl group is diamine represented by following formula [1].
The liquid-crystal aligning agent of Claim 6 in which a diamine component contains the diamine represented by following formula [32] further.

(In the above formula, k represents an integer of 1 to 20.)
The liquid crystal aligning agent according to claim 6, wherein the diamine represented by the formula [1] is contained in an amount of 20 to 90 mol% in all diamine components.
Furthermore, the liquid crystal aligning agent according to claim 8, wherein the diamine represented by the formula [32] is contained in an amount of 5 to 40 mol% in all diamine components.
A liquid crystal alignment film obtained by applying and baking the liquid crystal aligning agent according to any one of claims 1 to 9 on a substrate with an electrode.
A liquid crystal display element having the liquid crystal alignment film according to claim 10.