JPWO2014148596A1 - Liquid crystal aligning agent, liquid crystal aligning film, and liquid crystal display element using the same - Google Patents

Abstract

Includes a unit structure represented by any one of the following formulas (I) and (II) that maintains afterimage erasing time and orientation regulation power, is highly transparent, and is less likely to accumulate charge due to asymmetry of AC drive Liquid crystal aligning agent containing each polyamic acid: (In the formula, R1 represents a tetravalent organic group constituting an aromatic tetracarboxylic acid, and R2 represents a tetravalent organic group constituting a tetracarboxylic acid. R3 and R4 each represent a specific divalent organic group constituting a diamine.), A liquid crystal alignment film, and a liquid crystal display device using the same.

Description

  The present invention relates to a liquid crystal aligning agent, a liquid crystal alignment film, and a liquid crystal display element using the same used in a liquid crystal display element driven by applying a parallel electric field to a substrate.

  Conventionally, liquid crystal devices have been widely used as display units for personal computers, mobile phones, television receivers, and the like. The liquid crystal device includes, for example, a liquid crystal layer sandwiched between an element substrate and a color filter substrate, a pixel electrode and a common electrode that apply an electric field to the liquid crystal layer, an alignment film that controls the alignment of liquid crystal molecules in the liquid crystal layer, and a pixel electrode A thin film transistor (TFT) or the like for switching an electric signal supplied to the device is provided. As a driving method of liquid crystal molecules, a vertical electric field method such as a TN method and a VA method, and a horizontal electric field method such as an IPS method and an FFS method are known. In general, the lateral electric field method in which an electrode is formed only on one side of the substrate and an electric field is applied in a direction parallel to the substrate is compared with a conventional vertical electric field method in which a liquid crystal is driven by applying a voltage to the electrodes formed on the upper and lower substrates. It is known as a liquid crystal display device having a wide viewing angle characteristic and capable of high-quality display.

  Although the horizontal electric field type liquid crystal cell has excellent viewing angle characteristics, since there are few electrode parts formed in the substrate, if the voltage holding ratio of the liquid crystal alignment film is weak, sufficient voltage is not applied to the liquid crystal and the display contrast Decreases. In addition, static electricity is easily accumulated in the liquid crystal cell, and charges are accumulated in the liquid crystal cell by application of an asymmetric voltage generated by driving, and these accumulated charges disturb the alignment of the liquid crystal, or afterimages and image sticking. The display quality of the liquid crystal element is significantly reduced. In particular, in the horizontal electric field method, since the distance between the pixel electrode and the common electrode is shorter than in the vertical electric field method, a strong electric field acts on the alignment film and the liquid crystal layer, and this inconvenience is likely to be remarkable. It was.

  On the other hand, the liquid crystal alignment film is generally formed by printing a liquid crystal aligning agent, performing drying and baking, and then performing a rubbing process. However, in a horizontal electric field type liquid crystal cell, the liquid crystal alignment film is formed only on one side of the substrate. Due to the electrode structure, the substrate has large irregularities, and an insulator such as silicon nitride is sometimes formed on the substrate surface, so a liquid crystal aligning agent having better printability than conventional aligning agents is required. It has been. Furthermore, as compared with the conventional liquid crystal cell, there is a problem that peeling or rubbing due to the rubbing process is likely to occur, and these peeling and scratches deteriorate the display quality. Furthermore, in a system in which liquid crystal molecules that are horizontally aligned with respect to the substrate are driven by lateral electrolysis, such as an IPS (In-Plane Switching) system, the alignment regulating power is also important. If the alignment regulating force is weak, the liquid crystal does not return to the initial state when the liquid crystal is driven for a long time, resulting in a decrease in contrast or burn-in.

Patent Document 1 discloses an amic acid unit derived from an aromatic tetracarboxylic acid as a liquid crystal aligning agent that is excellent in printability and rubbing resistance and has little afterimage and image sticking when used in such a lateral electric field drive liquid crystal element. And a liquid crystal aligning agent containing both amic acid units derived from alicyclic tetracarboxylic acid by copolymerization or mixing. Further, as a liquid crystal alignment agent for obtaining a liquid crystal alignment film having excellent liquid crystal alignment properties, alignment regulating power, rubbing resistance, high voltage holding ratio, and reduced charge accumulation, Patent Document 2 discloses a film alignment film. A liquid crystal aligning agent comprising: a low-resistance polyimide precursor having a volume resistivity of 1 × 10 ¹⁰ to 1 × 10 ¹⁴ Ωcm; and a highly-oriented polyimide precursor or polyimide having a specific structure; and A liquid crystal display element using this liquid crystal aligning agent is disclosed.
However, with the improvement in performance of liquid crystal display elements, the characteristics required for the liquid crystal alignment film are becoming strict, and it is difficult to satisfy all the required characteristics only with the conventional technology.

International Publication WO02 / 33481 Pamphlet International Publication WO 2004/53583 Pamphlet

With the spread of multifunctional mobile phones (smartphones) and tablet terminals in recent years, when displaying high-definition images and videos such as digital photos and videos on the liquid crystal display elements installed in these devices, TVs, PCs, etc. High-quality display performance equivalent to or better than that has been demanded. For example, since mobile phones and tablet terminals are basically powered by batteries, the demand for improved backlight light utilization efficiency, that is, transparency of the liquid crystal alignment film, has become stricter than before in terms of saving power consumption. ing.
In addition, new screen displays and backlights for mobile phones and tablet terminals are frequently turned on and off, and new issues that are different from conventional applications have emerged, such as being watched by users from the moment they are displayed. It was.

  Therefore, the present inventors paid attention to the asymmetry in the AC drive of the liquid crystal display element as a factor related to the display characteristics immediately after the start of display. That is, the present invention provides a liquid crystal alignment film that maintains high properties that have been conventionally required, in particular, an afterimage erasing time and alignment regulation power, and that has high transparency and is less susceptible to charge accumulation due to AC drive asymmetry. This is the issue.

  As a result of intensive studies to solve the above-mentioned problems, the inventors of the present invention disclosed a highly oriented polyimide precursor in the liquid crystal alignment film disclosed in Patent Document 2 as a divalent organic group having a diamine structure. It was found that when a specific diamine was used, the layer separation ability was improved and a liquid crystal alignment film having excellent characteristics was obtained, and the present invention was completed.

（Ｒ^１は、芳香族系テトラカルボン酸を構成しうる、下記構造（ＩＩＩ）及び（ＩＶ）：

から選ばれる４価の有機基を示し、
Ｒ^２は、テトラカルボン酸を構成しうる、下記構造（Ｖ）又は（Ｖ’）：

（Ｒ^５、Ｒ^６、Ｒ^７、Ｒ^８はそれぞれ独立に水素原子又はメチル基を示す）を有する４価の有機基を示し、
Ｒ^３は、ジアミンを構成しうる下記構造（ＶＩ）又は（ＶＩＩ）：

（Ｒ^１２は、炭素原子数２〜８のアルキレン基を示す）
を有する２価の有機基を示し、
Ｒ^４は、ジアミンを構成しうる下記構造（ＶＩＩＩ）：

（Ｒ^９、Ｒ^１０はそれぞれ独立に水素原子、メチル基、エチル基、メトキシ基、エトキシ基から選ばれ、Ｒ^１１はエーテル結合又はメチレン基であり、ａは１〜４の整数を表す）
又は下記構造（ＩＸ）：

(Ｒ^１３及びＲ^１４は、互いに独立して、炭素数１〜３のアルキレン基であり、Ｙ^１及びＹ^２は、互いに独立して、単結合、−Ｏ−、−Ｓ−又はエステル結合であり、Ｚは、酸素原子又は硫黄原子である）から選ばれる、２価の有機基を示す。）That is, the present invention contains at least one polyamic acid containing a unit structure represented by the following formula (I) and at least one polyamic acid containing a unit structure represented by the following formula (II). A liquid crystal aligning agent is provided.

(R ¹ can constitute an aromatic tetracarboxylic acid, the following structures (III) and (IV):

A tetravalent organic group selected from:
R ² can constitute a tetracarboxylic acid, and has the following structure (V) or (V ′):

A tetravalent organic group having (R ⁵ , R ⁶ , R ⁷ , R ⁸ each independently represents a hydrogen atom or a methyl group);
R ³ can constitute a diamine and has the following structure (VI) or (VII):

(R ¹² represents an alkylene group having 2 to 8 carbon atoms)
A divalent organic group having
R ⁴ represents the following structure (VIII) that can constitute a diamine:

(R ⁹ and R ¹⁰ are each independently selected from a hydrogen atom, a methyl group, an ethyl group, a methoxy group, and an ethoxy group, R ¹¹ is an ether bond or a methylene group, and a represents an integer of 1 to 4)
Or the following structure (IX):

(R ¹³ and R ¹⁴ are each independently an alkylene group having 1 to 3 carbon atoms, and Y ¹ and Y ² are each independently a single bond, —O—, —S— or an ester bond. And Z is an oxygen atom or a sulfur atom). )

  In a further aspect of the present invention, there are provided a liquid crystal alignment film formed by applying a rubbing treatment after applying the above liquid crystal aligning agent on a substrate, firing, and a liquid crystal display device using the same.

  According to the present invention, a liquid crystal alignment film, a liquid crystal alignment film, and a liquid crystal display element using the liquid crystal alignment film, which maintain high afterimage erasing time and alignment regulation power, have high transparency, and are less likely to accumulate charge due to asymmetry of AC driving. Is provided.

The present invention is described in detail below.
The liquid crystal aligning agent of this invention is a composition used for forming a liquid crystal aligning film, and the polyamic acid 1 (henceforth PAA1) which has a structural unit represented by general formula (I), and general formula ( II) and polyamic acid 2 (hereinafter referred to as PAA2) having a structural unit represented by formula (II).

  The content of PAA1 and PAA2 is 20 to 70% by mass, more preferably 40 to 60% by mass, and most preferably about 50% by mass, based on the total amount of both. That is, with respect to the total amount of PAA1 and PAA2, PAA2 is 80 to 30% by mass, more preferably 60 to 40% by mass, and most preferably about 50% by mass. If the amount of PAA1 is too small, the alignment property and alignment regulating force of the liquid crystal deteriorate, and if the amount of PAA2 is too small, the charge storage characteristics of the liquid crystal alignment film deteriorate. Each of PAA1 and PAA2 contained in the liquid crystal aligning agent of the present invention may be one type or two or more types. In addition, in order to obtain a liquid crystal alignment film in which charge accumulation hardly occurs due to asymmetry of alternating current drive, when a liquid crystal alignment film is prepared by mixing PAA1 and PAA2, these polyamic acids are liable to cause layer separation. It is considered preferable.

Polyamic acid 1 (PAA1)
PAA1 is a polyimide precursor (polyamic acid) having a high orientation component, and has a structural unit represented by the formula (I). A liquid crystal alignment film including these structures is excellent in liquid crystal alignment and alignment regulating power. R ^{1 in the} above formula (I) includes a tetravalent organic group constituting an aromatic tetracarboxylic acid, which may be used alone or in combination of two or more. Examples of tetracarboxylic acids having this structure include pyromellitic acid, 2,3,6,7-naphthalenetetracarboxylic acid, 1,2,5,6-naphthalenetetracarboxylic acid, 1,4,5,8-naphthalenetetra. Carboxylic acid, 2,3,6,7-anthracenetetracarboxylic acid, 1,2,5,6-anthracenetetracarboxylic acid, 3,3 ′, 4,4′-biphenyltetracarboxylic acid, 2,3,3 ′ , 4-biphenyltetracarboxylic acid, bis (3,4-dicarboxyphenyl) ether, 3,3 ′, 4,4′-benzophenonetetracarboxylic acid, bis (3,4-dicarboxyphenyl) sulfone, bis (3 , 4-Dicarboxyphenyl) methane, 2,2-bis (3,4-dicarboxyphenyl) propane, 1,1,1,3,3,3-hexafluoro-2,2′-bis ( , 4-dicarboxyphenyl) propane, bis (3,4-dicarboxyphenyl) dimethylsilane, bis (3,4-dicarboxyphenyl) diphenylsilane, 2,3,4,5-pyridinetetracarboxylic acid, 2, 6-bis (3,4-dicarboxyphenyl) pyridine and the like can be mentioned. From the viewpoint of reducing the orientation and afterimage characteristics of the liquid crystal, R ¹ is preferably a tetravalent organic group selected from the following structures. ,

この構造を有するテトラカルボン酸としては、ピロメリット酸、２，３，６，７−ナフタレンテトラカルボン酸、３，３’，４，４’−ビフェニルテトラカルボン酸、３，３’，４，４’−ベンゾフェノンテトラカルボン酸、ビス（３，４−ジカルボキシフェニル）エーテルなどが挙げられ、特にピロメリット酸がより好ましい。これらの芳香族系テトラカルボン酸は、ＰＡＡ１を構成する式（Ｉ）のＲ^１のうち、少なくとも５０モル％以上であればよく、７０モル％以上、８０モル％以上又は９０モル％以上であることが好ましい。

Examples of the tetracarboxylic acid having this structure include pyromellitic acid, 2,3,6,7-naphthalenetetracarboxylic acid, 3,3 ′, 4,4′-biphenyltetracarboxylic acid, 3,3 ′, 4,4. Examples include '-benzophenone tetracarboxylic acid and bis (3,4-dicarboxyphenyl) ether, and pyromellitic acid is particularly preferable. These aromatic tetracarboxylic acids may be at least 50 mol% or more of R ¹ of the formula (I) constituting PAA1, and are 70 mol% or more, 80 mol% or more, or 90 mol% or more. It is preferable.

又は式（ＶＩＩ）：

の何れか又は両方の２価の有機基を含む必要がある。上記式（ＶＩＩ）のＲ^１２は、好ましくは炭素原子数２〜８のアルキレン基であり、より好ましくは炭素原子数３〜６のアルキレン基、例えば、プロピレン基、ブチレン基、ペンテン基及びヘキセン基などが挙げられ、さらに好ましくは炭素原子数が４又は５のブチレン基又はペンテン基である。
本発明の１つの好ましい実施形態では、式（Ｉ）におけるＲ^３は、１，３−ビス（４−アミノフェノキシ）ベンゼン又は１，５−ビス（４−アミノフェノキシ）ペンタンを構成する２価の有機基である。
式（Ｉ）のＲ^３における、これら特定構造を有するＲ^３の比率は、１０〜１００モル％であることが好ましく、より好ましくは５０〜１００モル％である。この比率が少なすぎると、フリッカの変動特性が悪化する場合がある。上記の特定構造を有するＲ^３と混在させる、その他のＲ^３の構造は特に限定されない。In the formula (I), R ³ includes a divalent organic group constituting a diamine together with the —NH— moiety, and may be one type or a mixture of two or more types. Although not at least one of formula (VI):

Or Formula (VII):

It is necessary to include either or both of the divalent organic groups. R ^{12 in the} above formula (VII) is preferably an alkylene group having 2 to 8 carbon atoms, more preferably an alkylene group having 3 to 6 carbon atoms, such as a propylene group, a butylene group, a pentene group and a hexene group. More preferably, it is a butylene group or pentene group having 4 or 5 carbon atoms.
In one preferred embodiment of the present invention, R ³ in formula (I) is divalent constituting 1,3-bis (4-aminophenoxy) benzene or 1,5-bis (4-aminophenoxy) pentane. Organic group.
The ratio of R ³ having these specific structures in R ³ of formula (I) is preferably 10 to 100 mol%, more preferably 50 to 100 mol%. If this ratio is too small, flicker fluctuation characteristics may deteriorate. Mix and R ³ having the above specific structure, other structures of R ³ is not particularly limited.

Specific examples of other diamine compounds constituting the structure of R ³ are listed below. p-phenylenediamine, 2,3,5,6-tetramethyl-p-phenylenediamine, 2,5-dimethyl-p-phenylenediamine, m-phenylenediamine, 2,4-dimethyl-m-phenylenediamine, 2, 5-diaminotoluene, 2,6-diaminotoluene, 2,5-diaminophenol, 2,4-diaminophenol, 3,5-diaminophenol, 3,5-diaminobenzyl alcohol, 2,4-diaminobenzyl alcohol, 4 , 6-diaminoresorcinol, 4,4′-diaminobiphenyl, 3,3′-dimethyl-4,4′-diaminobiphenyl, 3,3′-dimethoxy-4,4′-diaminobiphenyl, 3,3′-dihydroxy -4,4'-diaminobiphenyl, 3,3'-difluoro-4,4'-diaminobiphenyl, 3,3'-trif Fluoromethyl-4,4′-diaminobiphenyl, 3,4′-diaminobiphenyl, 3,3′-diaminobiphenyl, 2,2′-diaminobiphenyl, 2,3′-diaminobiphenyl, 4,4′-diaminodiphenylmethane, 3,3′-diaminodiphenylmethane, 3,4′-diaminodiphenylmethane, 2,2′-diaminodiphenylmethane, 2,3′-diaminodiphenylmethane, 4,4′-diaminodiphenyl ether, 3,3′-diaminodiphenyl ether, 3, 4'-diaminodiphenyl ether, 2,2'-diaminodiphenyl ether, 2,3'-diaminodiphenyl ether, 4,4'-sulfonyldianiline, 3,3'-sulfonyldianiline, bis (4-aminophenyl) silane, bis (3-aminophenyl) silane, dimethyl-bis (4-a Nophenyl) silane, dimethyl-bis (3-aminophenyl) silane, 4,4′-thiodianiline, 3,3′-thiodianiline, 4,4′-diaminodiphenylamine, 3,3′-diaminodiphenylamine, 3,4′- Diaminodiphenylamine, 2,2′-diaminodiphenylamine, 2,3′-diaminodiphenylamine, N-methyl (4,4′-diaminodiphenyl) amine, N-methyl (3,3′-diaminodiphenyl) amine, N-methyl (3,4'-diaminodiphenyl) amine, N-methyl (2,2'-diaminodiphenyl) amine, N-methyl (2,3'-diaminodiphenyl) amine, 4,4'-diaminobenzophenone, 3,3 '-Diaminobenzophenone, 3,4'-diaminobenzophenone, 1,4-diaminonaphthalene, 2,2'- Aminobenzophenone, 2,3'-diaminobenzophenone, 1,5-diaminonaphthalene, 1,6-diaminonaphthalene, 1,7-diaminonaphthalene, 1,8-diaminonaphthalene, 2,5-diaminonaphthalene, 2,6- Diaminonaphthalene, 2,7-diaminonaphthalene, 2,8-diaminonaphthalene, 1,2-bis (4-aminophenyl) ethane, 1,2-bis (3-aminophenyl) ethane, 1,3-bis (4 -Aminophenyl) propane, 1,3-bis (3-aminophenyl) propane, 1,4-bis (4-aminophenyl) butane, 1,4-bis (3-aminophenyl) butane, bis (3,5 -Diethyl-4-aminophenyl) methane, 1,4-bis (4-aminophenyl) benzene, 1,3-bis (4-aminophenyl) ben Zen, 1,4-bis (4-aminobenzyl) benzene, 1,3-bis (4-aminophenethyl) urea, N-methyl-2- (4-aminophenyl) ethylamine, 4,4 ′-[1, 4-phenylenebis (methylene)] dianiline, 4,4 ′-[1,3-phenylenebis (methylene)] dianiline, 3,4 ′-[1,4-phenylenebis (methylene)] dianiline, 3,4 ′ -[1,3-phenylenebis (methylene)] dianiline, 3,3 '-[1,4-phenylenebis (methylene)] dianiline, 3,3'-[1,3-phenylenebis (methylene)] dianiline, 1,4-phenylenebis [(4-aminophenyl) methanone], 1,4-phenylenebis [(3-aminophenyl) methanone], 1,3-phenylenebis [(4-aminophenyl) methanone ], 1,3-phenylenebis [(3-aminophenyl) methanone], 1,4-phenylenebis (4-aminobenzoate), 1,4-phenylenebis (3-aminobenzoate), 1,3-phenylenebis (4-aminobenzoate), 1,3-phenylenebis (3-aminobenzoate), bis (4-aminophenyl) terephthalate, bis (3-aminophenyl) terephthalate, bis (4-aminophenyl) isophthalate, bis ( 3-aminophenyl) isophthalate, N, N ′-(1,4-phenylene) bis (4-aminobenzamide), N, N ′-(1,3-phenylene) bis (4-aminobenzamide), N, N ′-(1,4-phenylene) bis (3-aminobenzamide), N, N ′-(1,3-phenylene) bis (3-aminobenzene) N, N′-bis (4-aminophenyl) terephthalamide, N, N′-bis (3-aminophenyl) terephthalamide, N, N′-bis (4-aminophenyl) isophthalamide, N, N′-bis (3-aminophenyl) isophthalamide, 9,10-bis (4-aminophenyl) anthracene, 4,4′-bis (4-aminophenoxy) diphenylsulfone, 2,2′-bis [4- (4-aminophenoxy) phenyl] propane, 2,2′-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane, 2,2′-bis (4-aminophenyl) hexafluoropropane, 2,2 '-Bis (3-aminophenyl) hexafluoropropane, 2,2'-bis (3-amino-4-methylphenyl) hexafluoropropane, 2,2' Bis (4-aminophenyl) propane, 2,2′-bis (3-aminophenyl) propane, 2,2′-bis (3-amino-4-methylphenyl) propane, 1,3-bis (3-amino) Phenoxy) propane, 1,4-bis (3-aminophenoxy) butane, 1,5-bis (3-aminophenoxy) pentane, 1,6-bis (3-aminophenoxy) hexane, 1,7- (3 -Aminophenoxy) heptane, 1,8-bis (3-aminophenoxy) octane, 1,9-bis (4-aminophenoxy) nonane, 1,9-bis (3-aminophenoxy) nonane, 1,10- ( 4-aminophenoxy) decane, 1,10- (3-aminophenoxy) decane, 1,11- (4-aminophenoxy) undecane, 1,11- (3-aminophenoxy) undecane 1,12- (4-aminophenoxy) dodecane, 1,12- (3-aminophenoxy) dodecane, bis (4-aminocyclohexyl) methane, bis (4-amino-3-methylcyclohexyl) methane, 3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, 1,10 -Diaminodecane, 1,11-diaminoundecane, 1,12-diaminododecane and the like can be mentioned. Of these, 4,4′-diaminodiphenylmethane, 1,3-bis (4-aminophenethyl) urea, and N-methyl-2- (4-aminophenyl) ethylamine are preferably used from the viewpoint of good orientation and the like. .
The other diamine compounds mentioned above are of one type depending on characteristics such as volume resistivity, rubbing resistance, ion density characteristics, transmittance, liquid crystal alignment characteristics, voltage holding characteristics and accumulated charges when used as a liquid crystal alignment film. Alternatively, two or more types can be mixed and used.

In the formula (VI), one or more arbitrary hydrogen atoms on the benzene ring may be substituted with a monovalent organic group other than the primary amino group. Examples of the monovalent organic group include an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a fluorine-containing alkyl group having 1 to 20 carbon atoms, and 2 carbon atoms. -20-containing fluorine-containing alkenyl group, C1-C20 fluorine-containing alkoxy group, cyclohexyl group, phenyl group, fluorine atom, or a group comprising a combination thereof. From the viewpoint of the orientation of the liquid crystal, an alkyl group having 1 to 4 carbon atoms, an alkenyl group having 2 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a fluorine-containing alkyl group having 1 to 4 carbon atoms, and 2 to 2 carbon atoms. A monovalent organic group selected from the group consisting of 4 fluorine-containing alkenyl groups and 1 to 4 carbon-containing fluorine-containing alkoxy groups is preferred. As a more preferred structure, the hydrogen atom on the benzene ring is unsubstituted.
Examples of the diamine having the structure of the above formula (VI) include 1,3-bis (4-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) benzene, etc. And 1,3-bis (4-aminophenoxy) benzene is preferred.

Polyamic acid 2 (PAA2)
PAA2 is a polyimide precursor (polyamic acid) that contributes to the charge storage characteristics of the liquid crystal alignment film, and has a structural unit represented by the general formula (II). The volume resistivity shown when the polyamic acid is used as a film is preferably 1 × 10 ¹⁰ to 1 × 10 ¹⁴ Ωcm. If this resistivity is too high, display burn-in and unevenness due to charge accumulation may occur, and if it is too low, the voltage holding characteristics may deteriorate.

R ^{2 in the} general formula (II) contains a tetravalent organic group constituting a tetracarboxylic acid, but it may be used alone or in combination of two or more. Examples of tetracarboxylic acids having this structure include 1,2,3,4-cyclobutanetetracarboxylic acid, 1,2,3,4-cycloheptanetetracarboxylic acid, 2,3,4,5-tetrahydrofurantetracarboxylic acid, 1,2,4,5-cyclohexanetetracarboxylic acid, 3,4-dicarboxy-1-cyclohexylsuccinic acid, 3,4-dicarboxy-1,2,3,4-tetrahydro-1-naphthalene succinic acid, bicyclo [3.3.0] octane-2,4,6,8-tetracarboxylic acid, 2,3,5 although such tricarboxy cyclopentyl acetic acid, from the viewpoint of the electrical characteristics of the resulting element, ^{R 2} is It is preferably a tetravalent organic group selected from the following structures (V) and (V ′),

（Ｒ^５、Ｒ^６、Ｒ^７、Ｒ^８はそれぞれ独立に水素原子又はメチル基を示す）
この構造を有するテトラカルボン酸としては、１，２，３，４−シクロブタンテトラカルボン酸または１，２，３，４−ブタンテトラカルボン酸二無水物またはそれらの誘導体などが挙げられ、特に１，２，３，４−シクロブタンテトラカルボン酸がより好ましい。これらのテトラカルボン酸は、ＰＡＡ２を構成する式（ＩＩ）のＲ^２のうち、少なくとも５０モル％以上であればよく、７０モル％以上、８０モル％以上又は９０モル％以上であることが好ましい。その他のＲ^２の構造は特に限定されないが、１，２，３，４−シクロヘプタンテトラカルボン酸、２，３，４，５−テトラヒドロフランテトラカルボン酸、１，２，４，５−シクロヘキサンテトラカルボン酸、３，４−ジカルボキシ−１−シクロヘキシルコハク酸、３，４−ジカルボキシ−１，２，３，４−テトラヒドロ−１−ナフタレンコハク酸、ビシクロ［３，３，０］オクタン−２，４，６，８−テトラカルボン酸、２，３，５−トリカルボキシシクロペンチル酢酸などを使用することができる。

(R ⁵ , R ⁶ , R ⁷ and R ⁸ each independently represents a hydrogen atom or a methyl group)
Examples of the tetracarboxylic acid having this structure include 1,2,3,4-cyclobutanetetracarboxylic acid, 1,2,3,4-butanetetracarboxylic dianhydride, or derivatives thereof. 2,3,4-cyclobutanetetracarboxylic acid is more preferred. These tetracarboxylic acids may be at least 50 mol% or more, preferably 70 mol% or more, 80 mol% or more, or 90 mol% or more of R ² of formula (II) constituting PAA2. . The structure of other R ² is not particularly limited, but 1,2,3,4-cycloheptanetetracarboxylic acid, 2,3,4,5-tetrahydrofurantetracarboxylic acid, 1,2,4,5-cyclohexanetetracarboxylic acid Acid, 3,4-dicarboxy-1-cyclohexylsuccinic acid, 3,4-dicarboxy-1,2,3,4-tetrahydro-1-naphthalene succinic acid, bicyclo [3,3,0] octane-2, 4,6,8-tetracarboxylic acid, 2,3,5-tricarboxycyclopentylacetic acid and the like can be used.

R ^{4 in the} formula (II) is a divalent organic group constituting a diamine, and these may be the same or different from each other, and may be used alone or in combination of two or more. May be. As diamines having these structures, p-phenylenediamine, m-phenylenediamine, 2,5-diaminotoluene, 2,6-diaminotoluene, 4,4′-diaminobiphenyl, 3,3′-dimethyl-4, 4'-diaminobiphenyl, 3,3'-dimethoxy-4,4'-diaminobiphenyl, diaminodiphenylmethane, diaminodiphenyl ether, 2,2'-diaminodiphenylpropane, bis (3,5-diethyl-4-aminophenyl) methane And aromatic diamines such as 1,3-bis (4-aminophenethyl) urea. Among these, from the viewpoint of afterimage characteristics, R ⁴ is preferably a divalent organic group independently selected from the following structures (VIII) and (IX).

（Ｒ^９、Ｒ^１０はそれぞれ独立に水素原子、メチル基、エチル基、メトキシ基、エトキシ基から選ばれ、Ｒ^１１はエーテル結合又はメチレン基であり、ａは１〜４の整数を表す）

(R ⁹ and R ¹⁰ are each independently selected from a hydrogen atom, a methyl group, an ethyl group, a methoxy group, and an ethoxy group, R ¹¹ is an ether bond or a methylene group, and a represents an integer of 1 to 4)

(Ｒ^１３及びＲ^１４は、互いに独立して、炭素数１〜３のアルキレン基であり、Ｙ^１及びＹ^２は、互いに独立して、単結合、−Ｏ−、−Ｓ−又はエステル結合であり、Ｚは、酸素原子又は硫黄原子である。）
この構造を有するジアミンとしては、４，４’−ジアミノジフェニルメタン、３，３’−ジアミノジフェニルメタン、３，４’−ジアミノジフェニルメタン、２，２’−ジアミノジフェニルメタン、２，３’−ジアミノジフェニルメタン、４，４’−ジアミノジフェニルエーテル、３，３’−ジアミノジフェニルエーテル、３，４’−ジアミノジフェニルエーテル、２，２’−ジアミノジフェニルエーテル、２，３’−ジアミノジフェニルエーテル、１，３−ビス（４−アミノフェネチル）ウレアなどが挙げられる。これら特定構造を有するＲ^４の比率は、５０〜１００モル％であることが好ましく、この比率が少なすぎると、残像特性が悪化する場合がある。

(R ¹³ and R ¹⁴ are each independently an alkylene group having 1 to 3 carbon atoms, and Y ¹ and Y ² are each independently a single bond, —O—, —S— or an ester bond. And Z is an oxygen atom or a sulfur atom.)
Diamines having this structure include 4,4′-diaminodiphenylmethane, 3,3′-diaminodiphenylmethane, 3,4′-diaminodiphenylmethane, 2,2′-diaminodiphenylmethane, 2,3′-diaminodiphenylmethane, 4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 2,2'-diaminodiphenyl ether, 2,3'-diaminodiphenyl ether, 1,3-bis (4-aminophenethyl) urea Etc. The ratio of R ⁴ having these specific structures is preferably 50 to 100 mol%, and if this ratio is too small, the afterimage characteristics may deteriorate.

In addition, as long as the object of the present invention is not impaired, other diamines may be used in combination with R ⁴ having the above specific structure, and these may be used alone or in combination of two or more. Also good. Specific examples thereof include p-phenylenediamine, 2,3,5,6-tetramethyl-p-phenylenediamine, 2,5-dimethyl-p-phenylenediamine, m-phenylenediamine, and 2,4-dimethyl-m. -Phenylenediamine, 2,5-diaminotoluene, 2,6-diaminotoluene, 2,5-diaminophenol, 2,4-diaminophenol, 3,5-diaminophenol, 3,5-diaminobenzyl alcohol, 2,4 -Diaminobenzyl alcohol, 4,6-diaminoresorcinol, 4,4'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dimethoxy-4,4'-diaminobiphenyl, 3,3′-dihydroxy-4,4′-diaminobiphenyl, 3,3′-difluoro-4,4′-biphenyl, 3, 3'-trifluoromethyl-4,4'-diaminobiphenyl, 3,4'-diaminobiphenyl, 3,3'-diaminobiphenyl, 2,2'-diaminobiphenyl, 2,3'-diaminobiphenyl, 4,4 '-Sulfonyldianiline, 3,3'-sulfonyldianiline, bis (4-aminophenyl) silane, bis (3-aminophenyl) silane, dimethyl-bis (4-aminophenyl) silane, dimethyl-bis (3- Aminophenyl) silane, 4,4′-thiodianiline, 3,3′-thiodianiline, 4,4′-diaminodiphenylamine, 3,3′-diaminodiphenylamine, 3,4′-diaminodiphenylamine, 2,2′-diaminodiphenylamine 2,3′-diaminodiphenylamine, N-methyl (4,4′-diaminodiphenyl) amine, N-methyl (3,3′-diaminodiphenyl) amine, N-methyl (3,4′-diaminodiphenyl) amine, N-methyl (2,2′-diaminodiphenyl) amine, N-methyl (2,3′-diaminodiphenyl) ) Amine, 4,4′-diaminobenzophenone, 3,3′-diaminobenzophenone, 3,4′-diaminobenzophenone, 1,4-diaminonaphthalene, 2,2′-diaminobenzophenone, 2,3′-diaminobenzophenone, 1,5-diaminonaphthalene, 1,6-diaminonaphthalene, 1,7-diaminonaphthalene, 1,8-diaminonaphthalene, 2,5-diaminonaphthalene, 2,6-diaminonaphthalene, 2,7-diaminonaphthalene, 2, , 8-diaminonaphthalene, 1,2-bis (4-aminophenyl) ethane, 1,2-bis (3-amino Phenyl) ethane, 1,3-bis (4-aminophenyl) propane, 1,3-bis (3-aminophenyl) propane, 1,4-bis (4aminophenyl) butane, 1,4-bis (3- Aminophenyl) butane, bis (3,5-diethyl-4-aminophenyl) methane, 1,4-bis (4-aminophenyl) benzene, 1,3-bis (4-aminophenyl) benzene, 1,4- Bis (4-aminobenzyl) benzene, 1,3-bis (4-aminophenethyl) urea, N-methyl-2- (4-aminophenyl) ethylamine, 4,4 ′-[1,4-phenylenebis (methylene) )] Dianiline, 4,4 ′-[1,3-phenylenebis (methylene)] dianiline, 3,4 ′-[1,4-phenylenebis (methylene)] dianiline, 3,4 ′-[1,3- Feni Bis (methylene)] dianiline, 3,3 ′-[1,4-phenylenebis (methylene)] dianiline, 3,3 ′-[1,3-phenylenebis (methylene)] dianiline, 1,4-phenylenebis [ (4-aminophenyl) methanone], 1,4-phenylenebis [(3-aminophenyl) methanone], 1,3-phenylenebis [(4-aminophenyl) methanone], 1,3-phenylenebis [(3 -Aminophenyl) methanone], 1,4-phenylenebis (4-aminobenzoate), 1,4-phenylenebis (3-aminobenzoate), 1,3-phenylenebis (4-aminobenzoate), 1,3- Phenylenebis (3-aminobenzoate), bis (4-aminophenyl) terephthalate, bis (3-aminophenyl) terephthalate, (4-aminophenyl) isophthalate, bis (3-aminophenyl) isophthalate, N, N ′-(1,4-phenylene) bis (4-aminobenzamide), N, N ′-(1,3- Phenylene) bis (4-aminobenzamide), N, N ′-(1,4-phenylene) bis (3-aminobenzamide), N, N ′-(1,3-phenylene) bis (3-aminobenzamide), N, N′-bis (4-aminophenyl) terephthalamide, N, N′-bis (3-aminophenyl) terephthalamide, N, N′-bis (4-aminophenyl) isophthalamide, N, N′— Bis (3-aminophenyl) isophthalamide, 9,10-bis (4-aminophenyl) anthracene, 4,4′-bis (4-aminophenoxy) diphenylsulfone, 2,2′-bis [ -(4-aminophenoxy) phenyl] propane, 2,2'-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane, 2,2'-bis (4-aminophenyl) hexafluoropropane, 2, 2′-bis (3-aminophenyl) hexafluoropropane, 2,2′-bis (3-amino-4-methylphenyl) hexafluoropropane, 2,2′-bis (4-aminophenyl) propane, 2, 2′-bis (3-aminophenyl) propane, 2,2′-bis (3-amino-4-methylphenyl) propane, 1,3-bis (4-aminophenoxy) propane, 1,3-bis (3 -Aminophenoxy) propane, 1,4-bis (4-aminophenoxy) butane, 1,4-bis (3-aminophenoxy) butane, 1,5-bis (4-aminophen) Xyl) pentane, 1,5-bis (3-aminophenoxy) pentane, 1,6-bis (4-aminophenoxy) hexane, 1,6-bis (3-aminophenoxy) hexane, 1,7-bis (4-aminophenoxy) heptane, 1,7- (3-aminophenoxy) heptane, 1,8-bis (4-aminophenoxy) octane, 1,8-bis (3-aminophenoxy) octane, 1,9- Bis (4-aminophenoxy) nonane, 1,9-bis (3-aminophenoxy) nonane, 1,10- (4-aminophenoxy) decane, 1,10- (3-aminophenoxy) decane, 1,11- (4-aminophenoxy) undecane, 1,11- (3-aminophenoxy) undecane, 1,12- (4-aminophenoxy) dodecane, 1,12- (3-amino Phenoxy) dodecane. Bis (4-aminocyclohexyl) methane, bis (4-amino-3-methylcyclohexyl) methane, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, 1,10-diaminodecane, 1,11-diaminoundecane, 1,12-diaminododecane and the like. Of these, 1,3-bis (4-aminophenethyl) urea is preferably used from the viewpoint of good electrical characteristics and the like.

Synthesis of polyamic acid When polyamic acid used for PAA1 or PAA2 is obtained by reaction of tetracarboxylic dianhydride and diamine, a method of mixing tetracarboxylic dianhydride and diamine in an organic solvent and reacting them Is simple.
The organic solvent used in the above reaction is not particularly limited as long as the generated polyamic acid dissolves. Specific examples are N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methylcaprolactam, dimethyl sulfoxide, tetramethylurea, pyridine, dimethylsulfone, hexamethyl. Examples thereof include sulfoxide and γ-butyrolactone. 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.

  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, In this invention, any of these methods may be sufficient. Further, 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 reacted in a mixed state in advance or may be reacted individually and sequentially.

  The temperature at the time of making a tetracarboxylic dianhydride component and a diamine component react in an organic solvent is 0-150 degreeC normally, Preferably it is 5-100 degreeC, More preferably, it is 10-80 degreeC. 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 reaction can be carried out at any concentration, but if the concentration is too low, it is difficult to obtain a high molecular weight polymer, and if the concentration is too high, the viscosity of the reaction solution becomes too high and uniform stirring is difficult. Therefore, Preferably it is 1-50 mass%, More preferably, it is 5-30 mass%. The initial reaction may be carried out at a high concentration, and then an organic solvent may be added.

The ratio of the tetracarboxylic dianhydride component: diamine component used in the polyamic acid polymerization reaction is preferably 1: 0.8 to 1.2 in terms of molar ratio. Moreover, since the polyamic acid obtained by making an excessive diamine component may increase the coloring of a solution, when the coloring of a solution is worrisome, said ratio should just be 1: 0.8-1. . Similar to the normal polycondensation reaction, the closer the molar ratio is to 1: 1, the higher the molecular weight of the polyamic acid obtained. If the molecular weight of the polyamic acid is too small, the strength of the coating film obtained therefrom may be insufficient. Conversely, if the molecular weight of the polyamic acid is too large, the solution viscosity when the liquid crystal aligning agent is used as the coating solution is low. It may become too high, and the workability at the time of coating film formation and the uniformity of a coating film may worsen.
The weight average molecular weight of such a polyamic acid is preferably 5,000 to 300,000, more preferably 10,000 to 200,000, and the number average molecular weight is preferably 2,500 to 300,000. It is 150,000, More preferably, it is 5,000-100,000.

  If you do not want to include the solvent used for the polymerization of the polyamic acid in the liquid crystal aligning agent of the present invention, or if there are unreacted monomer components or impurities in the reaction solution and you want to remove them, the polyamic acid Perform precipitation recovery and purification. As the method, a method of adding the polyamic acid solution to a stirring poor solvent and recovering the precipitate is simple. Although it does not specifically limit as a poor solvent used for precipitation collection | recovery of polyamic acid, Methanol, acetone, hexane, butyl cellosolve, heptane, methyl ethyl ketone, methyl isobutyl ketone, ethanol, toluene, benzene etc. can be illustrated. The polyamic acid precipitated by introducing it into a poor solvent can be recovered by filtration, washing and drying at room temperature or under reduced pressure at normal temperature or under reduced pressure. If this powder is further dissolved in a good solvent and reprecipitation is repeated 2 to 10 times, the polyamic acid can be purified. When the impurities cannot be removed by a single precipitation recovery operation, it is preferable to perform this purification step. In this case, it is preferable to use three or more kinds of poor solvents such as alcohols, ketones, and hydrocarbons as the poor solvent because the purification efficiency is further increased. The precipitation recovery and purification operations described above can be performed in the same manner when synthesizing polyamic acid alkyl ester and polyimide described later.

  When the polyamic acid is partially or wholly imidized, the production method is not particularly limited, but the polyamic acid obtained by reacting tetracarboxylic dianhydride and diamine may be imidized as it is in a solution. it can. At this time, in order to convert a part or all of the polyamic acid into polyimide, a method of dehydrating and ring-closing by heating or a method of chemically ring-closing using a known dehydration and ring-closing catalyst is employed. In the method by heating, an arbitrary temperature of 100 ° C. to 300 ° C., preferably 120 ° C. to 250 ° C. can be selected. In the method of chemically ring-closing, for example, pyridine, triethylamine and the like can be used in the presence of acetic anhydride and the like, and the temperature at this time can be selected from -20 ° C to 200 ° C.

Liquid crystal aligning agent The form of the liquid crystal aligning agent of the present invention described below is a coating solution containing PAA1 and PAA2, but other forms are acceptable as long as a uniform thin film can be formed on the substrate. May be. In order to obtain a coating solution containing PAA1 and PAA2, the reaction solution of each polyamic acid may be mixed as it is, or after dissolving the solid polyamic acid in an organic solvent, it may be mixed. The polyamic acid may be mixed while being dissolved in an organic solvent. As described above, the mixing ratio of PAA1 and PAA2 is preferably 2: 8 to 7: 3, more preferably 3: 8 to 7: 3, and even more preferably, by mass ratio (PAA1: PAA2). Is from 4: 6 to 6: 4, particularly preferably about 5: 5. By setting these ratios within this range, a liquid crystal aligning agent having good liquid crystal alignment properties and electrical characteristics can be obtained.

  The organic solvent is not particularly limited as long as it can dissolve the resin component contained therein, but specific examples thereof include N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl- 2-pyrrolidone, N-methylcaprolactam, 2-pyrrolidone, N-ethylpyrrolidone, N-vinylpyrrolidone, dimethylsulfoxide, tetramethylurea, pyridine, dimethylsulfone, hexamethylsulfoxide, γ-butyrolactone, and the like. May be used alone or in combination.

  Moreover, even if it is a solvent which does not dissolve a resin component alone, it can be mixed with the liquid crystal aligning agent of the present invention as long as the resin component does not precipitate. In particular, 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, propylene glycol monoacetate, propylene glycol diacetate, propylene glycol-1-monomethyl ether-2-acetate, propylene glycol-1-monoethyl ether-2-acetate, dipropylene glycol, 2- (2-ethoxy Propoxy) solvents with low surface tension such as propanol, lactate methyl ester, lactate ethyl ester, lactate n-propyl ester, lactate n-butyl ester, lactyl isoamyl ester By mix whenever, when applied to a substrate are known to coating uniformity is improved, also suitably used in the liquid crystal aligning agent of the present invention.

Although the coating liquid which is the liquid crystal aligning agent of this invention can change solid content concentration suitably by the setting of the thickness of the liquid crystal aligning film to form, it is preferable to set it as 1-10 mass%. If it is less than 1% by mass, it is difficult to form a uniform and defect-free coating film, and if it exceeds 10% by mass, the storage stability of the solution may be deteriorated.
In addition, in order to improve the adhesion of the coating film to the substrate, an additive such as a silane coupling agent may be added to the liquid crystal aligning agent of the present invention, and other resin components may be added. .

The liquid crystal aligning agent of the present invention obtained as described above can be filtered as necessary, applied to a substrate, dried and baked to form a coating film. By performing alignment treatment such as irradiation, it can be used as a liquid crystal alignment film.
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, but from the viewpoint of productivity, the transfer printing method is widely used industrially. Are also preferably used.

  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 the conveyance of the substrate or the like. If a specific example is given, the method of drying on a hotplate of 50-150 degreeC, Preferably 80-120 degreeC for 0.5 to 30 minutes, Preferably it is 1 to 5 minutes is taken.

Although baking of a liquid crystal aligning agent can be performed at 100-350 degreeC arbitrary temperatures, Preferably it is 150 to 300 degreeC, More preferably, it is 200 to 250 degreeC. When the liquid crystal aligning agent contains a polyimide precursor, the conversion rate from the polyimide precursor to the polyimide varies depending on the baking temperature, but the liquid crystal aligning agent of the present invention does not necessarily need to be 100% imidized. However, baking is preferably performed at a temperature higher by 10 ° C. or more than the heat treatment temperature required for the liquid crystal cell manufacturing process, such as sealing agent curing.
If the thickness of the coating film after baking is too thick, it will be 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 5 to 300 nm, preferably 10 to 100 nm. It is.

Liquid crystal display element 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. . If an example of liquid crystal cell production is given, a pair of substrates on which a liquid crystal alignment film is formed are usually 1 to 30 μm, preferably 2 to 10 μm, and a rubbing direction is preferably 0 to 270 °. 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. An existing rubbing apparatus can be used for the rubbing treatment for the liquid crystal alignment film. Examples of the material of the rubbing cloth at this time include cotton, rayon, and nylon. 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.

  Thus, since the liquid crystal display element produced using the liquid crystal aligning agent of this invention is excellent in the orientation of a liquid crystal, alignment control power, and has the outstanding electrical property, it is a contrast fall or image sticking. A liquid crystal display device that is unlikely to occur can be obtained. Among these liquid crystal display elements, the liquid crystal display element is particularly preferably used for a horizontal electric field type liquid crystal display element in which seizure due to the alignment regulating force easily occurs.

  The details of the production method of the present invention will be described below with reference to experimental methods and results obtained by examining the composition and blending ratio of raw materials, and examples that are typical production methods. The present invention is not limited to these examples.

Explanation of abbreviations used in this example (tetracarboxylic dianhydride)
CA-1: pyromellitic dianhydride CA-2: 1,2,3,4-cyclobutanetetracarboxylic dianhydride CA-3: 3,4-dicarboxy-1,2,3,4-tetrahydro- 1-Naphthalene succinic dianhydride

(Diamine)
DA-1: 4,4′-diaminodiphenyl ether DA-2: 4,4′-diaminodiphenylmethane DA-3: 1,3-bis (4-aminophenethyl) urea DA-4: 1,3-bis (4- Aminophenoxy) benzene DA-5: 1,5-bis (4-aminophenoxy) pentane DA-6: 4,4'-diaminodiphenylamine DA-7: N-methyl-2- (4-aminophenyl) ethylamine DA- 8: 1,3-bis (4-aminophenoxy) propane

(Organic solvent)
NMP: N-methyl-2-pyrrolidone GBL: γ-butyrolactone BCS: Butyl cellosolve

Each measurement method is shown below.
(Transmittance measurement (Evaluation of luminous transmittance))
After the obtained liquid crystal aligning agent is filtered through a 1.0 μm filter, the aligning agent is spin-coated on a quartz substrate, dried on a hot plate at 50 ° C. for 5 minutes, and then baked at 230 ° C. for 30 minutes. A polyimide film having a thickness of 100 nm was formed. A double-sided tape was applied only on the two sides facing the coating surface of the substrate, and was bonded to a quartz substrate on which nothing was formed. Liquid paraffin was poured into the simple cell thus prepared, and the transmittance was measured using UV-3100PC manufactured by Shimadzu Corporation. Luminous transmittance was calculated from the obtained data, and a value of 96% or more was defined as “good” and less than 96% was defined as “bad”. The evaluation results are shown in Table 3.

First, a substrate with electrodes was prepared. The substrate is a glass substrate having a size of 30 mm × 50 mm and a thickness of 0.7 mm. On the substrate, an ITO electrode having a solid pattern constituting a counter electrode as a first layer is formed. On the counter electrode of the first layer, a SiN (silicon nitride) film formed by the CVD method is formed as the second layer. The second layer SiN film has a thickness of 500 nm and functions as an interlayer insulating film. On the second SiN film, a comb-like pixel electrode formed by patterning an ITO film as the third layer is arranged to form two pixels, a first pixel and a second pixel. ing. The size of each pixel is 10 mm long and about 5 mm wide. At this time, the first-layer counter electrode and the third-layer pixel electrode are electrically insulated by the action of the second-layer SiN film.

  The pixel electrode of the third layer has a comb-like shape configured by arranging a plurality of dog-shaped electrode elements whose central portion is bent. The width in the short direction of each electrode element is 3 μm, and the distance between the electrode elements is 6 μm. Since the pixel electrode forming each pixel is formed by arranging a plurality of bent-shaped electrode elements in the central portion, the shape of each pixel is not rectangular, but in the central portion like the electrode elements. It has a shape that bends and resembles a bold-faced koji. Each pixel is divided into upper and lower portions with a central bent portion as a boundary, and has a first region on the upper side of the bent portion and a second region on the lower side.

  When the first region and the second region of each pixel are compared, the formation directions of the electrode elements of the pixel electrodes constituting them are different. That is, when the rubbing direction of the liquid crystal alignment film described later is used as a reference, the electrode element of the pixel electrode is formed to form an angle of + 10 ° (clockwise) in the first region of the pixel, and the pixel in the second region of the pixel. The electrode element of the electrode is formed so as to form an angle of −10 ° (clockwise). That is, in the first region and the second region of each pixel, the directions of the rotation operation (in-plane switching) of the liquid crystal induced by the voltage application between the pixel electrode and the counter electrode are mutually in the substrate plane. It is comprised so that it may become a reverse direction.

  Next, after the obtained liquid crystal aligning agent is filtered through a 1.0 μm filter, an ITO film is formed on the back surface as the prepared substrate with electrodes and a counter substrate, and a columnar spacer having a height of 4 μm. Each of the glass substrates having was spin-coated. Subsequently, after drying for 5 minutes on a 50 degreeC hotplate, it baked for 30 minutes at 230 degreeC, and obtained the polyimide film on each board | substrate as a 70 nm-thick coating film. The polyimide film is rubbed with a rayon cloth in a predetermined rubbing direction (roll diameter 120 mm, rotation speed 500 rpm, moving speed 30 mm / sec, pushing amount 0.3 mm), and then irradiated with ultrasonic waves in pure water for 1 minute. And dried at 80 ° C. for 10 minutes.

  After that, using the two kinds of substrates with the liquid crystal alignment film, the rubbing directions are combined so that they are antiparallel, the periphery is sealed except for the liquid crystal injection port, and an empty cell having a cell gap of 3.6 μm is formed. Produced. After liquid crystal (MLC-2041, manufactured by Merck & Co., Inc.) was vacuum-injected into the empty cell at room temperature, the injection port was sealed to obtain an anti-parallel alignment liquid crystal cell. The obtained liquid crystal cell constitutes an IPS mode liquid crystal display element. Thereafter, the obtained liquid crystal cell was heated at 110 ° C. for 1 hour and allowed to stand overnight before being used for each evaluation.

(Afterimage evaluation)
The afterimage was evaluated using the following optical system and the like.
The prepared liquid crystal cell is installed between two polarizing plates arranged so that the polarization axes are orthogonal to each other, and the LED backlight is turned on with no voltage applied, so that the brightness of transmitted light is minimized. The arrangement angle of the liquid crystal cell was adjusted.

  Next, a VT curve (voltage-transmittance curve) was measured while applying an AC voltage with a frequency of 30 Hz to the liquid crystal cell, and an AC voltage with a relative transmittance of 23% was calculated as a drive voltage.

  In the afterimage evaluation, a DC voltage of 2 V was simultaneously applied to drive the liquid crystal cell by applying an AC voltage of 30 Hz with a relative transmittance of 23%, and the liquid crystal cell was driven for 60 minutes. Thereafter, the applied DC voltage value was set to 0 V, and only the application of the DC voltage was stopped, and in that state, driving was continued for another 30 minutes.

The afterimage evaluation was defined as “good” when the relative transmittance recovered to 25% or less by 60 minutes after the application of the DC voltage was stopped. When it took 30 minutes or more for the relative transmittance to recover to 25% or less, it was evaluated as “bad”.
And the afterimage evaluation according to the method mentioned above was performed on the temperature conditions of the state whose temperature of a liquid crystal cell is 23 degreeC. The evaluation results are shown in Table 3.

(Evaluation of charge accumulation by asymmetry of AC drive)
The prepared liquid crystal cell is installed between two polarizing plates arranged so that the polarization axes are orthogonal to each other, and the LED backlight is turned on with no voltage applied, so that the brightness of transmitted light is minimized. The arrangement angle of the liquid crystal cell was adjusted.
Next, a VT curve (voltage-transmittance curve) was measured while applying an AC voltage with a frequency of 30 Hz to the liquid crystal cell, and an AC voltage with a relative transmittance of 50% was calculated as a drive voltage.
The LED light was shielded from hitting the liquid crystal cell. Further, a rectangular wave of 20 mV at a frequency of 1 kHz was applied to the liquid crystal cell for 30 minutes.

  After that, the AC drive is performed so that the relative transmittance becomes 50% simultaneously with the lighting of the LED, the VF (voltage-flicker curve) curve immediately after the lighting is measured, and the offset voltage value that cancels the charge accumulation due to the asymmetry of the AC drive is calculated. Calculated. Thereafter, the amount of change in the minimum offset voltage value was measured every minute, and the maximum voltage value when changed from immediately after lighting to 30 minutes was calculated. At that time, when the amount of change in the maximum offset voltage exceeded 20 mV, it was defined as “bad” and evaluated. When the change amount of the maximum offset voltage did not exceed 20 mV, it was defined as “good” and evaluated.

(Afterimage evaluation by long-term driving)
Using this liquid crystal cell, an AC voltage of 8 VPP was applied for 100 hours at a frequency of 30 Hz in a constant temperature environment of 60 ° C. Thereafter, the pixel electrode and the counter electrode of the liquid crystal cell were short-circuited and left as it was at room temperature for one day.
After leaving, the liquid crystal cell is placed between two polarizing plates arranged so that the polarization axes are orthogonal, and the backlight is turned on with no voltage applied so that the brightness of the transmitted light is minimized. The arrangement angle of the liquid crystal cell was adjusted. Then, the rotation angle when the liquid crystal cell was rotated from the angle at which the second region of the first pixel became darkest to the angle at which the first region became darkest was calculated as an angle Δ. Similarly, for the second pixel, the second area was compared with the first area, and a similar angle Δ was calculated. Then, the average value of the angle Δ values of the first pixel and the second pixel was calculated as the angle Δ of the liquid crystal cell. When the value of the angle Δ of the liquid crystal cell exceeded 0.2 degrees, it was defined as “defective” and evaluated. When the value of the angle Δ of the liquid crystal cell did not exceed 0.2 degrees, it was defined as “good” and evaluated.

[Synthesis of polymer]
<Synthesis Example 1>
To a 200 ml four-necked flask equipped with a stirrer and a nitrogen inlet tube, 14.3 g (48.0 mmol) of DA-4 and 141.3 g of N-methyl-2-pyrrolidone were added and stirred and dissolved while feeding nitrogen. . While stirring this diamine solution, 10.05 g (46.0 mmol) of CA-1 and N-methyl-2-pyrrolidone were added so that the solid content concentration was 12% by mass, and the mixture was stirred at a water temperature for 20 hours to be polyamic. An acid solution (abbreviated as P1) was obtained. It was 271 mPa * s when the viscosity at 25 degrees C of this polyamic acid (P1) solution was confirmed with the E-type viscosity meter (made by the Toki Sangyo company).
11.72 g of N-methyl-2-pyrrolidone and 13.18 g of butyl cellosolve were added to 27.82 g of this polyamic acid (P1) solution to obtain a liquid crystal aligning agent having a P1 concentration of 6.0% by mass.

<Synthesis Example 2>
In a 50 ml four-necked flask equipped with a stirrer and a nitrogen inlet tube, DA-4 (3.04 g, 10.4 mmol), DA-2 (0.52 g, 3.1 mmol), N-methyl-2-pyrrolidone, 36. 3 g was added and dissolved by stirring while feeding nitrogen. While stirring this diamine solution, 2.64 g (12.5 mmol) of CA-1 and N-methyl-2-pyrrolidone were added so that the solid content concentration was 12% by mass, and the mixture was stirred at a water temperature for 20 hours to polyamic. An acid solution (abbreviated as P2) was obtained. It was 316 mPa * s when the viscosity at 25 degrees C of this polyamic acid (P2) solution was confirmed with the E-type viscosity meter (made by the Toki Sangyo company).
7.87 g of N-methyl-2-pyrrolidone and 8.58 g of butyl cellosolve were added to 34.3 g of this polyamic acid (P2) solution to obtain a liquid crystal aligning agent having a P2 concentration of 6.0% by mass.

<Synthesis Example 3>
DA-5 (22.68 g, 79.2 mmol), DA-6 (10.52 g, 52.8 mmol), N-methyl-2-pyrrolidone 310. 1 g was added and dissolved by stirring while feeding nitrogen. While stirring the diamine solution, 27.21 g (124.7 mmol) of CA-1 and N-methyl-2-pyrrolidone were added so that the solid concentration was 12% by mass, and the mixture was stirred at a water temperature for 20 hours to be polyamic. An acid solution (abbreviated as P3) was obtained. It was 278 mPa * s when the viscosity at 25 degrees C of this polyamic acid (P3) solution was confirmed with the E-type viscosity meter (made by the Toki Sangyo company).
132.3 g of N-methyl-2-pyrrolidone and 134.5 g of butyl cellosolve were added to 271.4 g of this polyamic acid (P3) solution to obtain a liquid crystal aligning agent having a P3 concentration of 6.0% by mass.

<Synthesis Example 4>
18.5 g (92.0 mmol) of DA-1 and 211.4 g of N-methyl-2-pyrrolidone were added to a 300 ml four-necked flask equipped with a stirrer and a nitrogen introduction tube, and dissolved while stirring while feeding nitrogen. . While stirring this diamine solution, 17.56 g (89.5 mmol) of CA-2 and N-methyl-2-pyrrolidone were added so that the solid concentration was 12% by mass, and the mixture was stirred at a water temperature for 20 hours to be polyamic. An acid solution (abbreviated as P4) was obtained. It was 301 mPa * s when the viscosity at 25 degrees C of this polyamic acid (P4) solution was confirmed with the E-type viscosity meter (made by the Toki Sangyo company).
3.05 g of N-methyl-2-pyrrolidone solution containing 9.86 g of N-methyl-2-pyrrolidone and 1.0% by mass of 3-aminopropyltriethoxysilane in 25.2 g of this polyamic acid (P4) solution And 12.71 g of butyl cellosolve were added to obtain a liquid crystal aligning agent having a P4 concentration of 6.0% by mass.

<Synthesis Example 5>
To a 100 ml four-necked flask equipped with a stirrer and a nitrogen inlet tube, 6.15 g (31.0 mmol) of DA-2 and 70.65 g of N-methyl-2-pyrrolidone were added and stirred and dissolved while feeding nitrogen. . While stirring this diamine solution, 6.01 g (30.5 mmol) of CA-2 and N-methyl-2-pyrrolidone were added so that the solid content concentration was 12% by mass, and the mixture was stirred at a water temperature for 20 hours to be polyamic. An acid solution (abbreviated as P5) was obtained. It was 130 mPa * s when the viscosity at 25 degrees C of this polyamic acid (P5) solution was confirmed with the E-type viscosity meter (made by Toki Sangyo Co., Ltd.).
18.05 g of this polyamic acid (P5) solution 7.05 g of N-methyl-2-pyrrolidone and 2.18 g of N-methyl-2-pyrrolidone solution containing 1.0% by mass of 3-aminopropyltriethoxysilane. And 9.09 g of butyl cellosolve were added to obtain a liquid crystal aligning agent having a P5 concentration of 6.0% by mass.

<Synthesis Example 6>
DA-2 (4.02 g, 20.3 mmol) and DA-3 (2.60 g, 8.7 mmol) N-methyl-2-pyrrolidone (70.8 g) in a 100 ml four-necked flask equipped with a stirrer and a nitrogen inlet tube Was stirred and dissolved while feeding nitrogen. While stirring this diamine solution, 5.61 g (28.5 mmol) of CA-2 and N-methyl-2-pyrrolidone were added so that the solid concentration was 12% by mass, and the mixture was stirred at a water temperature for 5 hours to be polyamic. An acid solution (abbreviated as P6) was obtained. It was 249 mPa * s when the viscosity at 25 degrees C of this polyamic acid (P6) solution was confirmed with the E-type viscosity meter (made by Toki Sangyo Co., Ltd.).
18.13 g of this polyamic acid (P6) solution was 6.45 g of N-methyl-2-pyrrolidone and 2.13 g of N-methyl-2-pyrrolidone solution containing 1.0% by mass of 3-aminopropyltriethoxysilane. And 8.87 g of butyl cellosolve were added to obtain a liquid crystal aligning agent having a P6 concentration of 6.0% by mass.

<Synthesis Example 7>
DA-3 (10.6 g, 35.4 mmol) and DA-7 (3.55 g, 23.6 mmol) N-methyl-2-pyrrolidone (136.2 g) in a 100 ml four-necked flask equipped with a stirrer and a nitrogen inlet tube Was stirred and dissolved while feeding nitrogen. While stirring the diamine solution, 11.3 g (57.6 mmol) of CA-2 and N-methyl-2-pyrrolidone were added so that the solid content concentration was 10% by mass, and the mixture was stirred at a water temperature for 5 hours to be polyamic. An acid solution (abbreviated as P7) was obtained. It was 154 mPa * s when the viscosity at 25 degrees C of this polyamic acid (P7) solution was confirmed with the E-type viscosity meter (made by Toki Sangyo Co., Ltd.).
8.49 g of N-methyl-2-pyrrolidone solution containing 38.69 g of N-methyl-2-pyrrolidone and 1.0% by mass of 3-aminopropyltriethoxysilane in 58.97 g of this polyamic acid (P7) solution And 35.38 g of butyl cellosolve were added to obtain a liquid crystal aligning agent having a P7 concentration of 6.0% by mass.

<Synthesis Example 8>
In a 100 ml four-necked flask equipped with a stirrer and a nitrogen inlet tube, 3.80 g (13.0 mmol) of DA-4 and 3.35 g (13.0 mmol) of DA-8 were placed, and N-methyl-2-pyrrolidone 54 0.07 g was added and dissolved by stirring while feeding nitrogen. While stirring this diamine solution under water cooling, 2.84 g (13.0 mmol) of CA-1 and 18.0 g of N-methyl-2-pyrrolidone were added, and the mixture was stirred under water cooling under nitrogen atmosphere for 3 hours. Thereafter, 2.29 g (11.7 mmol) of CA-2 and 18.0 g of N-methyl-2-pyrrolidone were added and stirred to dissolve, and stirred for 3 hours under water cooling to obtain a solution of polyamic acid (A8). It was. It was 164 mPa * s when the viscosity at 25 degrees C of this polyamic acid (A8) solution was confirmed with the E-type viscosity meter (made by Toki Sangyo Co., Ltd.).
20.77 g of N-methyl-2-pyrrolidone and 10.06 g of butyl cellosolve were added to 20.77 g of this polyamic acid (P8) solution to obtain a liquid crystal aligning agent having a P8 concentration of 6.0% by mass.

<Synthesis Example 9>
DA-4 (4.38 g, 15.0 mmol), DA-8 (2.58 g, 10.0 mmol), and N-methyl-2-pyrrolidone (70.00) were added to a 100 ml four-necked flask equipped with a stirrer and a nitrogen inlet tube. 94 g was added and dissolved by stirring while feeding nitrogen. While stirring the diamine solution, 5.13 g (24.0 mmol) of CA-1 and N-methyl-2-pyrrolidone were added so that the solid concentration was 12% by mass, and the mixture was stirred at a water temperature for 20 hours to be polyamic. An acid solution (abbreviated as P9) was obtained. It was 202 mPa * s when the viscosity at 25 degrees C of this polyamic acid (P9) solution was confirmed with the E-type viscosity meter (made by Toki Sangyo Co., Ltd.).
8.21 g of N-methyl-2-pyrrolidone and 9.91 g of butyl cellosolve were added to 21.44 g of this polyamic acid (P9) solution to obtain a liquid crystal aligning agent having a P9 concentration of 6.0% by mass.

<Synthesis Example 10>
DA-4 (3.04 g, 10.0 mmol), DA-8 (4.03 g, 15.0 mmol), N-methyl-2-pyrrolidone, 72. 74 g was added and dissolved by stirring while feeding nitrogen. While stirring this diamine solution, 5.31 g (24.0 mmol) of CA-1 and N-methyl-2-pyrrolidone were added so that the solid concentration would be 12% by mass. An acid solution (abbreviated as P10) was obtained. It was 395 mPa * s when the viscosity at 25 degrees C of this polyamic acid (P10) solution was confirmed with the E-type viscosity meter (made by the Toki Sangyo company).
8.20 g of N-methyl-2-pyrrolidone and 9.46 g of butyl cellosolve were added to 20.42 g of this polyamic acid (P10) solution to obtain a liquid crystal aligning agent having a P10 concentration of 6.0% by mass.

<Synthesis Example 11>
In a 100 ml four-necked flask with a stirrer and a nitrogen inlet tube, 1.54 g (5.30 mmol) DA-4, 3.04 g (10.6 mmol) DA-5, 2.11 g DA-6 (10 .6 mmol) and 71.33 g of N-methyl-2-pyrrolidone were added and dissolved by stirring while feeding nitrogen. While stirring this diamine solution, 5.46 g (25.0 mmol) of CA-1 and N-methyl-2-pyrrolidone were added so that the solid content concentration was 12% by mass, and the mixture was stirred at a water temperature for 20 hours to polyamic. An acid solution (abbreviated as P11) was obtained. It was 895 mPa * s when the viscosity at 25 degrees C of this polyamic acid (P11) solution was confirmed with the E-type viscosity meter (made by Toki Sangyo Co., Ltd.).
10.20 g of N-methyl-2-pyrrolidone and 9.57 g of butyl cellosolve were added to 20.57 g of this polyamic acid (P11) solution to obtain a liquid crystal aligning agent having a P11 concentration of 4.6% by mass.

<Synthesis Example 13>
In a 200 ml four-necked flask equipped with a stirrer and a nitrogen inlet tube, 17.75 g (62.0 mmol) of DA-5 was added, 139.1 g of N-methyl-2-pyrrolidone was added, and the mixture was stirred and dissolved while feeding nitrogen. It was. While stirring this diamine solution under water cooling, 12.91 g (59.2 mmol) of CA-1 was added, and N-methyl-2-pyrrolidone was further added so that the solid content concentration was 12% by mass. The mixture was stirred for 20 hours while heating at 50 degrees to obtain a solution of polyamic acid (A1). It was 530 mPa * s when the viscosity at 25 degrees C of this polyamic acid (P12) solution was confirmed with the E-type viscosity meter (made by Toki Sangyo Co., Ltd.).
5.6 g of N-methyl-2-pyrrolidone solution containing 43.95 g of N-methyl-2-pyrrolidone and 1.0% by mass of 3-aminopropyltriethoxysilane in 50.00 g of this polyamic acid (P12) solution And 24.89 g of butyl cellosolve were added to obtain a liquid crystal aligning agent having an A1 concentration of 4.5 mass%.

<Synthesis Example 12>
In a 200 ml four-necked flask equipped with a stirrer and a nitrogen inlet tube, 7.97 g (40.0 mmol) of DA-6 was added, 98.6 g of N-methyl-2-pyrrolidone was added, and the mixture was stirred and dissolved while feeding nitrogen. It was. While stirring this diamine solution under water cooling, 6.96 g (35.5 mmol) of CA-2 and 35.9 g of N-methyl-2-pyrrolidone were added, and the mixture was stirred under water cooling for 3 hours under a nitrogen atmosphere. Thereafter, 1.98 g (10.0 mmol) of DA-2 and 17.9 g of N-methyl-2-pyrrolidone were added and dissolved by stirring. After DA-6 is dissolved, 3.00 g (10.0 mmol) of CA-3 and 26.9 g of N-methyl-2-pyrrolidone are added, and the mixture is again stirred under a nitrogen atmosphere for 3 hours under water cooling to polyamic. A solution of acid (P13) was obtained. It was 165 mPa * s when the viscosity at 25 degrees C of this polyamic acid (P12) solution was confirmed with the E-type viscosity meter (made by the Toki Sangyo company).
4.9 g of an N-methyl-2-pyrrolidone solution containing 10.55 g of N-methyl-2-pyrrolidone and 1.0% by mass of 3-aminopropyltriethoxysilane in 50.00 g of this polyamic acid (P13) solution. And 16.37 g of butyl cellosolve were added to obtain a solution having a P13 concentration of 6.0% by mass.

<Example 1>
The polyamic acid solution (P1) obtained in Synthesis Example 1 and the polyamic acid solution (P4) obtained in Synthesis Example 4 are mixed in an amount such that the mass ratio is 50:50, and the polyamic acid solution (A-1) is mixed. Obtained.

<Example 2>
The polyamic acid solution (P1) obtained in Synthesis Example 1 and the polyamic acid solution (P5) obtained in Synthesis Example 5 are mixed in an amount such that the mass ratio is 50:50, and the polyamic acid solution (A-2) is mixed. Obtained.

<Example 3>
The polyamic acid solution (P2) obtained in Synthesis Example 2 and the polyamic acid solution (P6) obtained in Synthesis Example 6 were mixed in an amount such that the mass ratio was 50:50, and the polyamic acid solution (A-3) was mixed. Obtained.

<Example 4>
The polyamic acid solution (P3) obtained in Synthesis Example 3 and the polyamic acid solution (P6) obtained in Synthesis Example 6 were mixed in an amount such that the mass ratio was 30:70, and the polyamic acid solution (A-4) was mixed. Obtained.

<Example 5>
The polyamic acid solution (P11) obtained in Synthesis Example 11 and the polyamic acid solution (P7) obtained in Synthesis Example 7 are mixed in an amount such that the mass ratio is 30:70, and the polyamic acid solution (A-5) is mixed. Obtained.

<Example 6>
The polyamic acid solution (P9) obtained in Synthesis Example 9 and the polyamic acid solution (P6) obtained in Synthesis Example 6 were mixed in an amount such that the mass ratio was 40:60, and the polyamic acid solution (A-6) was mixed. Obtained.

<Example 7>
The polyamic acid solution (P9) obtained in Synthesis Example 9 and the polyamic acid solution (P7) obtained in Synthesis Example 7 were mixed in an amount such that the mass ratio was 40:60, and the polyamic acid solution (A-7) was mixed. Obtained.

<Comparative Example 1>
The polyamic acid solution (P13) obtained in Synthesis Example 13 was used as Comparative Example (B-1) and used for evaluation.

<Comparative Example 2>
The polyamic acid solution (P4) obtained in Synthesis Example 4 was used as a comparative example (B-2) for evaluation.

<Comparative Example 3>
The polyamic acid solution (P8) obtained in Synthesis Example 8 was used as a comparative example (B-3) and used for evaluation.

<Comparative example 4>
The polyamic acid solution (P13) obtained in Synthesis Example 13 and the polyamic acid solution (P12) obtained in Synthesis Example 12 are mixed in an amount such that the mass to weight ratio is 20:80, and the polyamic acid solution (B-4) is mixed. Got.

<Comparative Example 5>
The polyamic acid solution (P10) obtained in Synthesis Example 10 and the polyamic acid solution (P6) obtained in Synthesis Example 6 were mixed in an amount such that the mass ratio was 40:60, and the polyamic acid solution (B-5) was mixed. Obtained.

Table 1 shows the ratio of tetracarboxylic dianhydride component and diamine component for P1 to P13 used in the preparation of the polyamic acid solutions in Examples 1 to 7 and Comparative Examples 1 to 5.
Table 2 shows the mixing ratio of each polyamic acid solution in Examples 1 to 7 and Comparative Examples 1 to 5.
Furthermore, the films prepared using the polyamic acid solutions of Examples 1 to 7 and Comparative Examples 1 to 5, and the luminous transmittance evaluation obtained by the liquid crystal cell, the afterimage evaluation, the afterimage evaluation by long-term driving, the AC driving The results of charge accumulation value evaluation by asymmetry are shown in Table 3.

  As described above, the polyamic acid of the present invention produced in Examples 1 to 6 is good in any of luminous transmittance evaluation, afterimage evaluation, afterimage evaluation by long-term driving, and charge accumulation value evaluation by asymmetry of AC driving. Although the polyamic acid produced in Comparative Examples 1 to 4 showed a poor result in any of the above evaluation items, the polyamic acid of the present invention was evaluated particularly in charge accumulation value evaluation by asymmetry of AC drive. A significant difference from the performance of the acid was obtained.

Claims (7)

A liquid crystal comprising at least one polyamic acid containing a unit structure represented by the following formula (I) and at least one polyamic acid containing a unit structure represented by the following formula (II) Alignment agent.

(R ¹ can constitute an aromatic tetracarboxylic acid, the following structures (III) and (IV):

A tetravalent organic group selected from:
R ² can constitute a tetracarboxylic acid, and has the following structure (V) or (V ′):

A tetravalent organic group having (R ⁵ , R ⁶ , R ⁷ , R ⁸ each independently represents a hydrogen atom or a methyl group);
R ³ represents the following structure (VI) that can constitute a diamine:

Or Formula (VII):

(R ¹² represents an alkylene group having 2 to 8 carbon atoms)
A divalent organic group having
R ⁴ represents the following structure (VIII) that can constitute a diamine:

(R ⁹ and R ¹⁰ are each independently selected from a hydrogen atom, a methyl group, an ethyl group, a methoxy group, and an ethoxy group, R ¹¹ is an ether bond or a methylene group, and a represents an integer of 1 to 4)
Or the following structure (IX)

(In the formula, R ¹³ and R ¹⁴ are each independently an alkylene group having 1 to 3 carbon atoms, and Y ¹ and Y ² are each independently a single bond, —O—, —S— or An ester bond, and Z represents an oxygen atom or a sulfur atom). )   The content ratio of the polyamic acid component composed of the unit structure represented by the formula (I) and the polyamic acid component composed of the unit structure represented by the formula (II) is from 2: 8 to 7: by mass ratio. The liquid crystal aligning agent of Claim 1 which is 3. The R ³ in the formula (I) is a divalent organic group capable of constituting 1,3-bis (4-aminophenoxy) benzene or 1,5-bis (4-aminophenoxy) pentane. 2. A liquid crystal aligning agent according to 2. The liquid crystal aligning agent according to any one of claims 1 to 3, wherein R ⁴ in the formula (II) is an organic group constituting diaminodiphenyl ether, diaminodiphenylmethane, or bis (4-aminophenethyl) urea. R ¹ in the formula (I) is an organic group capable of constituting pyromellitic acid, and R ² in the formula (II) is an organic group capable of constituting a cyclobutanetetracarboxylic acid. A liquid crystal aligning agent according to claim 1.   The liquid crystal aligning film formed by performing the rubbing process after apply | coating and baking the liquid crystal aligning agent as described in any one of Claims 1-5 on a board | substrate.   The liquid crystal display element using the liquid crystal aligning film formed by performing the rubbing process after apply | coating and baking the liquid crystal aligning agent as described in any one of Claims 1-5 on a board | substrate.