JP4900571B2 - Vertical liquid crystal aligning agent and vertical liquid crystal display element - Google Patents

Description

  The present invention relates to a vertical alignment type liquid crystal display element capable of reducing liquid crystal dropping unevenness and liquid crystal fusion portion unevenness in a liquid crystal dropping method (ODF). More specifically, the present invention relates to a vertical liquid crystal aligning agent that provides a vertical liquid crystal alignment film having a low residual voltage and a high voltage holding ratio, and a vertical liquid crystal display element including the vertical liquid crystal alignment film.

Currently, as a liquid crystal display element, a liquid crystal alignment film made of polyamic acid, polyimide, or the like is formed on the surface of a substrate on which a transparent conductive film is provided to form a liquid crystal display element substrate. A nematic liquid crystal layer having positive dielectric anisotropy is formed in a cell having a sandwich structure so that the major axis of the liquid crystal molecules is continuously twisted 90 degrees from one substrate to the other. A TN type liquid crystal display element having a so-called TN type (Twisted Nematic) liquid crystal cell is known.
Further, STN (Super Twisted Nematic) type liquid crystal display elements and vertical alignment type liquid crystal display elements, which have a higher contrast than TN type liquid crystal display elements and have less viewing angle dependency, have been developed. This STN type liquid crystal display element uses nematic liquid crystal blended with a chiral agent which is an optically active substance as liquid crystal, and the major axis of liquid crystal molecules is continuously twisted over 180 degrees between substrates. The birefringence effect generated by the above is utilized.

  In recent years, the development of new liquid crystal display elements has also been active, and as one of them, two electrodes for driving a liquid crystal are arranged in a comb shape on one substrate, and an electric field parallel to the substrate surface is arranged. A lateral electric field type liquid crystal display element that generates liquid crystal and controls liquid crystal molecules has been proposed (see Patent Document 1). This element is generally called an in-plane switching type (IPS type), and is known for its excellent wide viewing angle characteristics. Recently, an optical compensation film is used to further improve the wide viewing angle characteristics, so that it is possible to obtain a wide viewing angle comparable to that of a cathode ray tube without tone reversal or color change.

As a new liquid crystal display element different from the above, a vertical called the MVA (Multi domain Vertical Alignment) method or PVA (Patterned Vertical Alignment) method in which liquid crystal molecules having negative dielectric anisotropy are aligned perpendicularly to the substrate. Oriented liquid crystal display elements have been put into practical use. These MVA type and PVA type liquid crystal display elements are excellent not only in viewing angle and contrast, but also in the manufacturing process, such as not having to rub in the formation of the liquid crystal alignment film. Suitable for upsizing such as commercial use.
In general, in order to manufacture a liquid crystal display element, a step of injecting and filling liquid crystal into a gap (cell gap) between two substrates on which a liquid crystal alignment film is formed is necessary. For filling and filling the liquid crystal, a vacuum filling method in which liquid crystal is filled between substrates of a liquid crystal display element by utilizing a pressure difference between atmospheric pressure and vacuum is generally performed. Since a considerable amount of time is required for the liquid crystal to flow through the gap between the meters, it takes time for the manufacturing process, which is a big problem particularly in a large panel.

With the recent increase in substrate size, a liquid crystal dropping method (ODF method) has been developed in order to solve the problems in the above-described vacuum injection method. This is because the required amount of liquid crystal is dropped on the substrate on which the liquid crystal alignment film is formed, and bonded to the other substrate in a vacuum, and then the sealant for sealing the liquid crystal is UV-cured to cure the entire surface of the panel. This is a method capable of filling the liquid crystal. However, in this method, since the liquid crystal is directly dropped on the liquid crystal alignment film, the liquid crystal alignment film is loaded more drastically than the conventional vacuum injection method, and there are many liquid crystal dropping points. There has been a problem that alignment unevenness occurs in a liquid crystal dropping portion, a fusion portion of liquid crystals, and the like, resulting in a display defect of the liquid crystal display element. Generally, a vertical liquid crystal alignment film needs to express a hydrophobic component on the film surface in order to vertically align the liquid crystal. However, since the hydrophobic component weakens the interaction with the liquid crystal, the wettability of the liquid crystal is extremely high. It ’s bad. As a result, a strong load is applied when the liquid crystal is dropped or the liquid crystal is expanded, so that it is considered that alignment unevenness occurs. To date, this defect has been solved by optimizing the manufacturing process to reduce the load on the liquid crystal alignment film, such as reducing the amount of liquid crystal dripped and reducing the liquid crystal dripping pressure. With the increase in size, it has become impossible to suppress display defects by the suppression by the manufacturing process so far, and improvement from the liquid crystal alignment film has been demanded.
Japanese Patent Laid-Open No. 7-261181

  An object of the present invention is to provide a vertical liquid crystal aligning agent which can reduce liquid crystal alignment unevenness due to the ODF method by improving liquid crystal wettability in a vertical liquid crystal alignment film, and which provides a high voltage holding ratio and low residual DC. There is. Still other objects and advantages of the present invention will become apparent from the following description.

  According to the present invention, the above objects and advantages of the present invention are as follows. (I) The following formula (I-1)

Here, P ¹ and Q ¹ are tetravalent and divalent organic groups, respectively .
In represented by amic acid repeating unit and / or

ここで、Ａ^１およびＡ^２の少なくともいずれか一方はフッ素原子またはフッ化アルキル基であり、他方は水素原子またはアルキル基である、

ここで、Ａ ^３ およびＡ ^４ の少なくともいずれか一方はフッ素原子またはフッ化アルキル基であり、他方は水素原子またはアルキル基である、
で表わされる、フッ素原子を含有する４価の有機基を、１〜５０モル％で含有する前記液晶配向剤により達成される。
Here, P ² and Q ² are tetravalent and divalent organic groups, respectively.
A vertical alignment type liquid crystal aligning agent characterized by containing a polymer consisting of imide repeating units represented by:
P ¹ in the above formula (I-1) and P ² in the above formula (I-2) are each independently represented by the following formula (II-1 -1 ) or (II-1-2)

Wherein at least one hand of A ¹ and A ² is a fluorine atom or a fluorinated alkyl group and the other is a hydrogen atom or an alkyl group,

Here, at least one of A ³ and A ⁴ is a fluorine atom or a fluorinated alkyl group, and the other is a hydrogen atom or an alkyl group.
It is achieved by the liquid crystal aligning agent containing 1 to 50 mol% of a tetravalent organic group containing a fluorine atom represented by:

  According to the present invention, the above objects and advantages of the present invention are secondly achieved by a vertical liquid crystal display device comprising a vertical liquid crystal alignment film obtained from the vertical liquid crystal aligning agent. .

The vertical liquid crystal alignment film formed by the vertical liquid crystal aligning agent of the present invention can shorten the manufacturing process time and improve the yield by introducing a liquid crystal dropping method, so that it is optimal for large substrates and has excellent cost performance. It is suitable for obtaining an element. Furthermore, the vertical liquid crystal alignment film formed by the vertical liquid crystal aligning agent of the present invention is excellent in electrical characteristics and can be suitably used for constituting a liquid crystal display element.
The liquid crystal display element of the present invention can be effectively used in various devices, and is suitable for display devices such as a desktop computer, wristwatch, table clock, mobile phone, counting display board, word processor, personal computer, and liquid crystal television. Can be used.

  Hereinafter, the present invention will be described in detail.

As described above, the vertical alignment liquid crystal aligning agent of the present invention (hereinafter also referred to as “liquid crystal aligning agent of the present invention”) is an amic acid repeating unit represented by the above formula (I-1) and / or the above formula (I). -2) and a polymer composed of imide repeating units.
The polyamic acid comprising the above polyamic acid repeating unit is obtained by reacting a tetracarboxylic dianhydride and a diamine compound in an organic solvent. The tetracarboxylic dianhydride used is divided into those containing a fluorine atom that gives P ¹ in formula (I-1) and those containing no fluorine atom.

[Tetracarboxylic dianhydride]
Examples of tetracarboxylic dianhydrides containing no fluorine atom include butanetetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2-dimethyl-1,2, 3,4-cyclobutanetetracarboxylic dianhydride, 1,2-diethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-dimethyl-1,2,3,4-cyclobutanetetra Carboxylic dianhydride, 1,3-diethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-dichloro-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-tetramethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 1,2,4 5- Chlohexanetetracarboxylic dianhydride, 3,3 ′, 4,4′-dicyclohexyltetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentylacetic acid dianhydride, 1,2,4-tricarboxycyclopentyl Acetic acid dianhydride, 3,5,6-tricarboxynorbornane-2-acetic acid dianhydride, 2,3,4,5-tetrahydrofurantetracarboxylic dianhydride, 1,3,3a, 4,5,9b- Hexahydro-5 (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] -furan-1,3-dione, 1,3,3a, 4,5,9b-hexahydro-5 Methyl-5 (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] -furan-1,3-dione, 1,3,3a, 4,5,9b-hexahydro-5 Echi Ru-5 (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] -furan-1,3-dione, 1,3,3a, 4,5,9b-hexahydro-7- Methyl-5 (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] -furan-1,3-dione, 1,3,3a, 4,5,9b-hexahydro-7- Ethyl-5 (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] -furan-1,3-dione, 1,3,3a, 4,5,9b-hexahydro-8- Methyl-5 (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] -furan-1,3-dione, 1,3,3a, 4,5,9b-hexahydro-8- Ethyl-5 (tetrahydro-2,5-dioxo-3-furanyl) -na [1,2-c] -furan-1,3-dione, 1,3,3a, 4,5,9b-hexahydro-5,8-dimethyl-5 (tetrahydro-2,5-dioxo-3-furanyl ) -Naphtho [1,2-c] -furan-1,3-dione, 5- (2,5-dioxotetrahydrofural) -3-methyl-3-cyclohexene-1,2-dicarboxylic dianhydride, Aliphatic compounds such as bicyclo [2.2.2] -oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, compounds represented by the following formulas (1) and (2) And alicyclic tetracarboxylic dianhydrides;

(Wherein R ⁸ and R ¹⁰ represent a divalent organic group having an aromatic ring, R ⁹ and R ¹¹ represent a hydrogen atom or an alkyl group, and a plurality of R ⁹ and R ¹¹ are the same. But it may be different.)
Pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenylsulfone tetracarboxylic dianhydride, 1,4,5, 8-naphthalene tetracarboxylic dianhydride, 2,3,6,7-naphthalene tetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyl ether tetracarboxylic dianhydride, 3,3 ′, 4,4′-dimethyldiphenylsilanetetracarboxylic dianhydride, 3,3 ′, 4,4′-tetraphenylsilanetetracarboxylic dianhydride, 1,2,3,4-furantetracarboxylic dianhydride 4,4′-bis (3,4-dicarboxyphenoxy) diphenyl sulfide dianhydride, 4,4′-bis (3,4-dicarboxyphenoxy) diphenylsulfone dianhydride, 4,4′-bis ( 3,4-dicar Boxyphenoxy) diphenylpropane dianhydride, 3,3 ′, 4,4′-perfluoroisopropylidene diphthalic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, bis (Phthalic acid) phenylphosphine oxide dianhydride, p-phenylene-bis (triphenylphthalic acid) dianhydride, m-phenylene-bis (triphenylphthalic acid) dianhydride, bis (triphenylphthalic acid) -4 , 4′-diphenyl ether dianhydride, bis (triphenylphthalic acid) -4,4′-diphenylmethane dianhydride, ethylene glycol-bis (anhydro trimellitate), propylene glycol-bis (anhydro trimellitate) 1,4-butanediol-bis (anhydrotrimellitate), 1,6-hexanediol-bis (anhydride) Aromatic tetracarboxylic dianhydrides such as 1,8-octanediol-bis (anhydrotrimellitate), 2,2-bis (4-hydroxyphenyl) propane-bis (anhydrotrimellitate) Can be mentioned. These tetracarboxylic dianhydrides are used alone or in combination of two or more.
Among these tetracarboxylic dianhydrides, tetravalent organic compounds represented by the formula (IV-1) described in claim 2 are used as P ¹ of the amic acid repeating unit represented by the formula (I-1). A group of formula (IV)

Here, the definitions of R ¹ , R ² , R ³ , R ⁴ and R ⁵ are the same as those in the above formula (IV-1).
The tetracarboxylic dianhydride represented by these is preferable. Examples of such preferred tetracarboxylic dianhydrides include 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2-diethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-diethyl- 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-tetramethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 2,3,5-tri Carboxycyclopentyl acetic acid dianhydride, 1,2,4-tricarboxycyclopentyl acetic acid dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 1,2,4,5-cyclo Xanthatetracarboxylic dianhydride, 1,3,3a, 4,5,9b-hexahydro-8-methyl-5 (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c]- Furan-1,3-dione, 1,3,3a, 4,5,9b-hexahydro-8-ethyl-5 (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c]- An example is furan-1,3-dione. Among these, from the viewpoint of solubility and coating properties, 2,3,5-tricarboxycyclopentylacetic acid dianhydride, 1,2,4-tricarboxycyclopentylacetic acid dianhydride, 1,3,3a, 4, 5,9b-Hexahydro-8-methyl-5 (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] -furan-1,3-dione, 1,3,3a, 4 5,9b-Hexahydro-8-ethyl-5 (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] -furan-1,3-dione, 3,3 ′, 4,4 '-Benzophenone tetracarboxylic dianhydride and 1,2,3,4-cyclopentanetetracarboxylic dianhydride are particularly preferred. The tetracarboxylic dianhydride represented by the above formula (IV) is preferably contained in an amount of 10 mol% or more based on the total tetracarboxylic dianhydride, more preferably 20 mol% or more from the viewpoint of improving the properties, More preferably, it is at least mol%. At this time, as other tetracarboxylic dianhydrides, it is preferable to use alicyclic tetracarboxylic dianhydrides in order to sufficiently obtain the effect of the liquid crystal aligning agent of the present invention.

  On the other hand, the tetracarboxylic dianhydride containing a fluorine atom includes the following formula (II)

Here, at least one of A ¹ and A ² or at least one of A ³ and A ⁴ is a fluorine atom or a fluorinated alkyl group, and the other is a hydrogen atom or an alkyl group. Tetracarboxylic dianhydrides containing fluorine atoms are preferred.
Examples of the tetracarboxylic dianhydride containing a fluorine atom include 2,2-bis (1,3-dioxo-1,3-dihydroisobenzofuran-6-yl) -1,1,1,3,3. 3, -hexafluoropropane, 1-trifluoromethyl-2,3,5,6-benzenetetracarboxylic dianhydride and 1,4-ditrifluoromethyl-2,3,5,6-benzenetetracarboxylic acid Mention may be made of anhydrides. The fluorine-containing tetracarboxylic dianhydride is preferably used in an amount of 1 to 50 mol%, more preferably 20 to 50 mol% based on the total tetracarboxylic dianhydride in order to sufficiently obtain the effects of the present invention. preferable.

[Diamine compound]
The diamine compound used is divided into those containing a fluorine atom and those not containing a fluorine atom that give Q ¹ in formula (I-1). Examples of the diamine compound not containing a fluorine atom include p-phenylenediamine, m-phenylenediamine, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylethane, 4,4′-diaminodiphenyl sulfide, and 4,4 ′. -Diaminodiphenyl sulfone, 3,3'-dimethyl-4,4'-diaminobiphenyl, 4,4'-diaminobenzanilide, 4,4'-diaminodiphenyl ether, 1,5-diaminonaphthalene, 2,2'-dimethyl -4,4'-diaminobiphenyl, 5-amino-1- (4'-aminophenyl) -1,3,3-trimethylindane, 6-amino-1- (4'-aminophenyl) -1,3 3-trimethylindane, 3,4'-diaminodiphenyl ether, 3,3'-diaminobenzophenone, 3,4'-diaminoben Phenone, 4,4′-diaminobenzophenone, 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 [4- (4-aminophenoxy) phenyl] sulfone, 1,4-bis (4-aminophenoxy) benzene, 1,3-bis ( 4-aminophenoxy) benzene, 1,3-bis (3-aminophenoxy) benzene, 9,9-bis (4-aminophenyl) -10-hydroanthracene, 2,7-diaminofluorene, 9,9-bis ( 4-aminophenyl) fluorene, 4,4′-methylene-bis (2-chloroaniline), 2,2 ′, 5,5′-tetrachloro-4,4′-dia Minobiphenyl, 2,2′-dichloro-4,4′-diamino-5,5′-dimethoxybiphenyl, 3,3′-dimethoxy-4,4′-diaminobiphenyl, 1,4,4 ′-(p- Aromatic diamines such as phenyleneisopropylidene) bisaniline, 4,4 ′-(m-phenyleneisopropylidene) bisaniline, 4- (4-n-heptylcyclohexyl) phenoxy-2,4-diaminobenzene;
1,1-metaxylylenediamine, 1,3-propanediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, 4,4-diaminoheptamethylenediamine, 1 , 4-diaminocyclohexane, isophoronediamine, tetrahydrodicyclopentadienylenediamine, hexahydro-4,7-methanoindanylene methylenediamine, tricyclo [6.2.1.0 ^2,7 ] -undecylenedimethyldiamine, 4 Aliphatic and cycloaliphatic diamines such as 4,4'-methylenebis (cyclohexylamine);
2,3-diaminopyridine, 2,6-diaminopyridine, 3,4-diaminopyridine, 2,4-diaminopyrimidine, 5,6-diamino-2,3-dicyanopyrazine, 5,6-diamino-2,4 -Dihydroxypyrimidine, 2,4-diamino-6-dimethylamino-1,3,5-triazine, 1,4-bis (3-aminopropyl) piperazine, 2,4-diamino-6-isopropoxy-1,3 , 5-triazine, 2,4-diamino-6-methoxy-1,3,5-triazine, 2,4-diamino-6-phenyl-1,3,5-triazine, 2,4-diamino-6-methyl -S-triazine, 2,4-diamino-1,3,5-triazine, 4,6-diamino-2-vinyl-s-triazine, 2,4-diamino-5-phenylthiazole, 2,6- Aminopurine, 5,6-diamino-1,3-dimethyluracil, 3,5-diamino-1,2,4-triazole, 6,9-diamino-2-ethoxyacridine lactate, 3,8-diamino-6 Examples thereof include diamine compounds such as phenylphenanthridine, 1,4-diaminopiperazine, 3,6-diaminoacridine, and bis (4-aminophenyl) phenylamine. These diamine compounds can be used alone or in combination of two or more.
Among these diamine compounds, Q ¹ of the amic acid repeating unit represented by the formula (I-1) is represented by the formulas (V ₁ ) and (V ₂ ).

Here, R ⁶ is a divalent organic group having an alicyclic skeleton having 4 to 40 carbon atoms, and R ⁷ is an alkyl group having 10 to 20 carbon atoms and an alicyclic skeleton having 4 to 40 carbon atoms. X is a single bond, —O—, —CO—, —COO—, —OCO—, —NHCO—, —CONH—, —S—, a methylene group, 2 carbon atoms. Diamines represented by 6 to 6 alkylene groups and phenylene groups are preferred. Preferred examples of the diamine include compounds represented by the following formulas (3) to (5) as diamine compounds represented by the formula (V ₁ ), and examples of the diamine compound represented by the formula (V ₂ ): The compounds represented by (6) to (16) can be mentioned.

The diamine compounds represented by the formulas (V ₁ ) and (V ₂ ) are preferably used in an amount of 10 to 60 mol%, more preferably 20 to 50 mol%, based on the total diamine compounds.

  On the other hand, as a diamine compound containing a fluorine atom, the following formula (III)

Here, at least one of A ⁵ and A ⁶ is a fluorine atom or a fluorinated alkyl group, the other is a hydrogen atom or an alkyl group, and A ⁷ and A ⁸ are hexafluoropropylidene groups. The diamine compound represented is preferred. Examples of the fluorine-containing diamine compound include 4,4′-diamino-2,2′-bis (trifluoromethyl) biphenyl, 2,2-bis (4-aminophenyl) hexafluoropropane, and 2,2-bis [ 4- (4-aminophenoxy) phenyl] hexafluoropropane, 2,2-bis [4- (4-amino-2-trifluoromethylphenoxy) phenyl] hexafluoropropane, 4,4′-bis [(4- Mention may be made of amino-2-trifluoromethyl) phenoxy] -octafluorobiphenyl.
Such a fluorine-containing diamine compound is preferably used in an amount of 1 to 60 mol%, more preferably 10 to 40 mol% based on the total diamine.
The polymer having an imide repeating unit represented by the formula (I-2) of the present invention can be produced by dehydrating and ring-closing a polyamic acid composed of an amic acid repeating unit represented by the formula (I-1). it can.

[Synthesis of polyamic acid]
The ratio of tetracarboxylic dianhydride and diamine used in the polyamic acid synthesis reaction is 0.2 to 2.2 based on 1 equivalent of amino group of diamine and tetracarboxylic dianhydride acid anhydride group. A ratio of 0 equivalent is preferable, and a ratio of 0.8 to 1.2 equivalent is more preferable. The polyamic acid synthesis reaction is preferably performed in an organic solvent under a temperature condition of −20 ° C. to 150 ° C., more preferably 0 to 100 ° C.
Here, the organic solvent is not particularly limited as long as it can dissolve the synthesized polyamic acid. For example, 1-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, dimethyl sulfoxide And aprotic polar solvents such as γ-butyrolactone, tetramethylurea and hexamethylphosphortriamide; and phenolic solvents such as m-cresol, xylenol, phenol and halogenated phenol. The amount of organic solvent used (α) is such that the total amount (β) of tetracarboxylic dianhydride and diamine compound is 0.1 to 30% by weight based on the total amount of the reaction solution (α + β). It is preferable that

In addition, alcohols, ketones, esters, ethers, halogenated hydrocarbons, hydrocarbons, etc., which are poor solvents for polyamic acid, are used in combination with the organic solvent as long as the resulting polyamic acid does not precipitate. be able to. Specific examples of such poor solvents include, for example, methyl alcohol, ethyl alcohol, isopropyl alcohol, cyclohexanol, 4-hydroxy-4-methyl-2-pentanone, ethylene glycol, propylene glycol, 1,4-butanediol, triethylene glycol. , Ethylene glycol monomethyl ether, ethyl lactate, butyl lactate, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, methyl acetate, ethyl acetate, butyl acetate, methyl methoxypropionate, ethyl ethoxypropionate, diethyl oxalate, malon Acid diethyl, diethyl ether, ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol-n-propyl ether, ethylene glycol-i Propyl ether, ethylene glycol-n-butyl ether, ethylene glycol dimethyl ether, ethylene glycol ethyl ether acetate, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, tetrahydrofuran, dichloromethane 1,2-dichloroethane, 1,4-dichlorobutane, trichloroethane, chlorobenzene, o-dichlorobenzene, hexane, heptane, octane, benzene, toluene, xylene and the like.
As described above, a reaction solution obtained by dissolving polyamic acid is obtained. The reaction solution is poured into a large amount of poor solvent to obtain a precipitate, and the precipitate is dried under reduced pressure to obtain a polyamic acid. The polyamic acid can be purified by dissolving the polyamic acid again in an organic solvent and then precipitating with a poor solvent once or several times.

[End-modified polymer]
The polyamic acid polymer in the present invention may be a terminal-modified type having a controlled molecular weight. By using this terminal-modified polymer, the coating characteristics of the liquid crystal aligning agent can be improved without impairing the effects of the present invention. Such a terminal-modified polymer can be synthesized by adding an acid monoanhydride, a monoamine compound, a monoisocyanate compound or the like to the reaction system when synthesizing a polyamic acid. Here, as the acid monoanhydride, for example, maleic anhydride, phthalic anhydride, itaconic anhydride, n-decyl succinic anhydride, n-dodecyl succinic anhydride, n-tetradecyl succinic anhydride , N-hexadecyl succinic anhydride and the like. Examples of monoamine compounds include aniline, cyclohexylamine, n-butylamine, n-pentylamine, n-hexylamine, n-heptylamine, n-octylamine, n-nonylamine, n-decylamine, and n-undecylamine. N-dodecylamine, n-tridecylamine, n-tetradecylamine, n-pentadecylamine, n-hexadecylamine, n-heptadecylamine, n-octadecylamine, n-eicosylamine, etc. Can do. Examples of the monoisocyanate compound include phenyl isocyanate and naphthyl isocyanate.

[Imidized polymer]
The imidized polymer constituting the liquid crystal aligning agent of the present invention can be prepared by dehydrating and ring-closing the polyamic acid. The polyamic acid is dehydrated and closed by (i) a method in which the polyamic acid is heated, or (ii) the polyamic acid is dissolved in an organic solvent, and a dehydrating agent and a dehydrating ring-closing catalyst are added to this solution and heated as necessary. By the method. The reaction temperature in the method (i) of heating the polyamic acid is usually 50 to 300 ° C, preferably 120 to 250 ° C. When the reaction temperature is less than 50 ° C., the dehydration ring-closing reaction does not proceed sufficiently, and when the reaction temperature exceeds 200 ° C., the molecular weight of the imidized polymer obtained may decrease.

[Logarithmic viscosity of polymer]
The polyamic acid and / or imidized polymer thus obtained has a logarithmic viscosity (η _ln ) value of preferably 0.05 to 10 dl / g, more preferably 0.05 to 5 dl / g. .
The value of the logarithmic viscosity (η _ln ) in the present invention is determined by measuring the viscosity at 30 ° C. for a solution having a concentration of 0.5 g / 100 ml using N-methyl-2-pyrrolidone as a solvent. ).

[Vertical alignment type liquid crystal alignment agent]
Examples of the organic solvent constituting the liquid crystal aligning agent of the present invention include N-methyl-2-pyrrolidone, γ-butyrolactone, γ-butyrolactam, N, N-dimethylformamide, N, N-dimethylacetamide, 4-hydroxy- 4-methyl-2-pentanone, ethylene glycol monomethyl ether, butyl lactate, butyl acetate, methyl methoxypropionate, ethyl ethoxypropionate, ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol-n-propyl ether , Ethylene glycol-i-propyl ether, ethylene glycol-n-butyl ether (butyl cellosolve), ethylene glycol dimethyl ether, ethylene glycol ethyl ether acetate, diethylene glycol dimethyl Examples include ether, diethylene glycol diethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether acetate, and diethylene glycol monoethyl ether acetate.

  The solid content concentration in the liquid crystal aligning agent of the present invention is selected in consideration of viscosity, volatility, etc., but is preferably in the range of 1 to 10% by weight. That is, the liquid crystal aligning agent of the present invention is applied to the substrate surface to form a resin film that becomes a liquid crystal aligning film. When the solid content concentration is less than 1% by weight, the film thickness of the resin film is If the solid content concentration exceeds 10% by weight, the resin film becomes too thick to obtain a good liquid crystal alignment film. In addition, the viscosity of the liquid crystal aligning agent increases, resulting in poor coating characteristics.

The liquid crystal aligning agent of this invention may contain the functional silane containing compound and the epoxy compound from a viewpoint which improves the adhesiveness with respect to the substrate surface within the range which does not impair the target physical property. Examples of such functional silane-containing compounds include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 2-aminopropyltrimethoxysilane, 2-aminopropyltriethoxysilane, and N- (2-aminoethyl). -3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-ureidopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, N-ethoxycarbonyl-3-amino Propyltrimethoxysilane, N-ethoxycarbonyl-3-aminopropyltriethoxysilane, N-triethoxysilylpropyltriethylenetriamine, N-trimethoxysilylpropyltriethylenetriamine, 10-trimethoxysilyl- , 4,7-triazadecane, 10-triethoxysilyl-1,4,7-triazadecane, 9-trimethoxysilyl-3,6-diazanonyl acetate, 9-triethoxysilyl-3,6-diazanonyl acetate N-benzyl-3-aminopropyltrimethoxysilane, N-benzyl-3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltriethoxysilane, N -Bis (oxyethylene) -3-aminopropyltrimethoxysilane, N-bis (oxyethylene) -3-aminopropyltriethoxysilane, etc. can be mentioned.
The compounding ratio of these functional silane-containing compounds is 60 parts by weight or less, preferably 50 parts by weight or less with respect to 100 parts by weight of the total amount of polyamic acid and / or imidized polymer.

Examples of such epoxy compounds include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, and 1,6-hexane. diglycidyl ether, glycerin diglycidyl ether, 2,2-dibromo-neopentyl glycol diglycidyl ether, 1,3,5,6- tetraglycidyl-2,4-hexanediol, N, N, N ', N' - Tetraglycidyl-m-xylenediamine, N, N, N ′, N′-tetraglycidyl-2,2′-dimethyl-4,4′-diaminobiphenyl, N, N, N ′, N′-tetraglyci Le-4,4'-diaminobenzene, 1,3-bis (N, N-diglycidyl aminomethyl) cyclohexane, N, N, N ', N' - tetraglycidyl-4,4'-diaminodiphenylmethane, 3- (N-allyl-N-glycidyl) aminopropyltrimethoxysilane, 3- (N, N-diglycidyl) aminopropyltrimethoxysilane and the like can be mentioned. Particularly preferably, polyethylene glycol diglycidyl ether, N, N, N ′, N′-tetraglycidyl-4,4′-diaminodiphenylmethane, 1,3,5,6-tetraglycidyl-2,4-hexanediol, N, N, N ′, N′-tetraglycidyl-2,2′-dimethyl-4,4′-diaminobiphenyl, N, N, N ′, N′-tetraglycidyl-4,4′-diaminobenzene, 1,3 -Bis (N, N-diglycidylaminomethyl) cyclohexane and the like.
The compounding ratio of these epoxy compounds is 60 parts by weight or less, preferably 5 to 50 parts by weight with respect to 100 parts by weight of the total amount of polyamic acid and / or imidized polymer.

[Liquid crystal display element]
The vertical liquid crystal display element of the present invention can be manufactured, for example, by the following method.

(1) The liquid crystal aligning agent of the present invention is applied to one surface of a substrate provided with a patterned transparent conductive film by a method such as a roll coater method, a spinner method, a printing method, an ink jet method, etc. Is heated to form a coating film. Here, as the substrate, for example, a glass such as float glass or soda glass; a transparent substrate made of a plastic such as polyethylene terephthalate, polybutylene terephthalate, polyethersulfone, or polycarbonate can be used. As a transparent conductive film provided on one surface of the substrate, an NESA film (registered trademark of PPG, USA) made of tin oxide (SnO ₂ ), an ITO film made of indium oxide-tin oxide (In ₂ O ₃ —SnO ₂ ), etc. Can be used. For patterning these transparent conductive films, a photo-etching method or a method using a mask in advance is used. In applying the liquid crystal aligning agent, for example, a functional silane-containing compound or a functional titanium-containing compound can be applied in advance in order to further improve the adhesion between the substrate surface and the resin film. The heating temperature after application of the liquid crystal aligning agent is preferably 80 to 300 ° C, more preferably 120 to 250 ° C. The liquid crystal aligning agent of the present invention forms a resin film that becomes an alignment film by removing the organic solvent after coating. However, when imidization has not progressed completely, dehydration ring closure proceeds by further heating. It is also possible to obtain a more imidized resin film. The film thickness of the formed resin film is preferably 0.001 to 1 μm, more preferably 0.005 to 0.5 μm. Further, on the formed vertical liquid crystal alignment film, a structure may be formed using a photosensitive resin on a substrate by a technique as disclosed in JP-A-2002-327058. The straight liquid crystal alignment film may be formed on the substrate formed with the above-described method.

(2) Two substrates on which the vertical liquid crystal alignment film is formed as described above are manufactured, the two substrates are arranged to face each other with a gap (cell gap) therebetween, and the peripheral portions of the two substrates are sealed. A liquid crystal cell is formed by laminating using an agent, injecting and filling liquid crystal into the cell gap defined by the substrate surface and the sealing agent, and sealing the injection hole. And a liquid crystal display element is obtained by arrange | positioning a polarizing plate to the outer surface of a liquid crystal cell, ie, the transparent substrate side which comprises a liquid crystal cell.
Here, as the sealing agent, for example, an epoxy resin containing a curing agent and aluminum oxide spheres as a spacer can be used.

Examples of the liquid crystal include nematic liquid crystal and smectic liquid crystal. Among them, nematic liquid crystal is preferable, for example, Schiff base liquid crystal, azoxy liquid crystal, biphenyl liquid crystal, phenyl cyclohexane liquid crystal, ester liquid crystal, terphenyl liquid crystal, biphenyl cyclohexane liquid crystal, pyrimidine liquid crystal, dioxane liquid crystal, bicyclooctane. Type liquid crystal, cubane type liquid crystal and the like can be used. Further, for these liquid crystals, for example, cholesteric liquid crystals such as cholestyl chloride, cholesteryl nonate, cholesteryl carbonate, and chiral agents such as those sold under the trade names “C-15” and “CB-15” (manufactured by Merck). Etc. can also be used. Furthermore, a ferroelectric liquid crystal such as p-decyloxybenzylidene-p-amino-2-methylbutylcinnamate can also be used.
Further, as a polarizing plate to be bonded to the outer surface of the liquid crystal cell, a polarizing film or an H film in which a polarizing film called an H film that absorbs iodine while sandwiching and stretching polyvinyl alcohol is sandwiched between cellulose acetate protective films. The polarizing plate which consists of itself can be mentioned.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.
Various measurements in Reference Examples, Examples and Comparative Examples were performed by the following methods.

(1) Evaluation of liquid crystal wettability When a contact angle between a liquid crystal and an alignment film was measured after dropping a liquid crystal (MLC-2038 manufactured by Merck) on a substrate coated with an alignment film (film thickness: 80 nm), the contact angle was measured. Of 15 degrees or less was considered good wettability.
(2) Measurement of voltage holding ratio After applying a voltage of 5 V to the liquid crystal display element at 60 ° C. with an application time of 60 microseconds and a span of 167 microseconds, the voltage holding ratio 167 milliseconds after the application release was measured. .
(3) Measurement of residual voltage A voltage of 17.0 V DC was applied to the liquid crystal display element at an ambient temperature of 100 ° C. for 20 hours and allowed to cool at room temperature for 15 minutes immediately after the DC voltage was turned off. Was determined by the flicker elimination method. At this time, the case where the residual voltage was 800 mV or less was considered good.
(4) Confirmation of Vertical Alignment When the voltage of the vertical alignment liquid crystal display element was turned off and the state when a 4 V AC voltage was applied was visually observed, the case where there was no light leakage or poor alignment was considered good.

Synthesis Example 1 (Synthesis of polyamic acid)
As tetracarboxylic dianhydride, 13.3 g (0.06 mol) of 2,3,5,6-benzenetetracarboxylic dianhydride and 9.0 g of 2,3,5-tricarboxycyclopentylacetic acid dianhydride ( 0.04 mol), p-phenylenediamine 3.2 g (0.03 mol) as a diamine compound, 4,4′-diamino-2,2′-bis (trifluoromethyl) biphenyl 9.6 g (0.03 mol) ) And 20.9 g (0.04 mol) of the compound represented by the above formula (7) were dissolved in 185 g of N-methyl-2-pyrrolidone and reacted at 40 ° C. for 4 hours. The reaction solution was then poured into a large excess of methyl alcohol to precipitate the reaction product. Thereafter, it was washed with methyl alcohol and dried at 40 ° C. under reduced pressure for 15 hours to obtain 32.9 g of a polyamic acid having a logarithmic viscosity of 1.21 dl / g (referred to as “polyamic acid (PA-1)”). It was.

Synthesis Example 2 (Synthesis of polyamic acid)
As the diamine compound, 19.2 g (0.06 mol) of 4,4′-diamino-2,2′-bis (trifluoromethyl) biphenyl and 20.9 g (0.04 mol) of the compound represented by the above formula (7) ) Was used in the same manner as in Synthesis Example 1 to obtain 59.1 g of a polyamic acid having a logarithmic viscosity of 1.16 dl / g (referred to as “polyamic acid (PA-2)”).

Synthesis Example 3 (Synthesis of polyamic acid)
As the diamine compound, 4.9 g (0.045 mol) of p-phenylenediamine, 4.8 g (0.015 mol) of 4,4′-diamino-2,2′-bis (trifluoromethyl) biphenyl, and the above formula (7 In the same manner as in Synthesis Example 1 except that 20.9 g (0.04 mol) of the compound represented by formula (1) is used, a polyamic acid having a logarithmic viscosity of 1.31 dl / g (hereinafter referred to as “polyamic acid (PA-3)”). 49.9 g).

Synthesis Example 4 (Synthesis of polyamic acid)
The diamine compound is represented by 4.3 g (0.04 mol) of p-phenylenediamine, 10.0 g (0.03 mol) of 2,2-bis (4-aminophenyl) hexafluoropropane, and the above formula (7). A polyamic acid having a logarithmic viscosity of 1.02 dl / g (referred to as “polyamic acid (PA-4)”) as in Synthesis Example 1 except that 15.7 g (0.03 mol) of the compound was used. 48. 5 g was obtained.

Synthesis Example 5 (Synthesis of polyamic acid)
As a diamine compound, 6.4 g (0.03 mol) of 2,2′-dimethyl-4,4′-diaminobiphenyl, 12.8 g of 4,4′-diamino-2,2′-bis (trifluoromethyl) biphenyl ( 0.04 mol) and a polyamic acid having a logarithmic viscosity of 1.11 dl / g in the same manner as in Synthesis Example 1 except that 15.7 g (0.03 mol) of the compound represented by the above formula (7) was used. 42.2 g of “polyamic acid (PA-5)”.

Synthesis Example 6 (Synthesis of polyamic acid)
As a diamine compound, 8.5 g (0.04 mol) of 2,2′-dimethyl-4,4′-diaminobiphenyl, 10.0 g (0.03 mol) of 2,2-bis (4-aminophenyl) hexafluoropropane In the same manner as in Synthesis Example 1 except that 15.7 g (0.03 mol) of the compound represented by the above formula (7) was used, a polyamic acid having a logarithmic viscosity of 1.09 dl / g (hereinafter referred to as “polyamic acid ( PA-7) ”) was obtained.

Synthesis Example 7 (Synthesis of polyamic acid)
As tetracarboxylic dianhydride, 2,3,5,6-benzenetetracarboxylic dianhydride 13.1 g (0.06 mol) and 1,2,3,4-cyclobutanetetracarboxylic dianhydride 7.8 g 30.4 g of a polyamic acid (this is referred to as “polyamic acid (PA-7)”) having a logarithmic viscosity of 1.22 dl / g was obtained in the same manner as in Synthesis Example 1 except that (0.04 mol) was used. .

Synthesis Example 8 (Synthesis of polyamic acid)
As the diamine compound, 4.9 g (0.045 mol) of p-phenylenediamine, 4.8 g (0.015 mol) of 4,4′-diamino-2,2′-bis (trifluoromethyl) biphenyl, and the above formula (7 In the same manner as in Synthesis Example 6 except that 20.9 g (0.04 mol) of the compound represented by formula (1) is used, a polyamic acid having a logarithmic viscosity of 1.27 dl / g (referred to as “polyamic acid (PA-8)”). 47.7 g was obtained.

Synthesis Example 9 (Synthesis of polyamic acid)
2,3,5,6-benzenetetracarboxylic dianhydride 13.1 g (0.06 mol) and 1,2,3,4-cyclobutanetetracarboxylic dianhydride 7.8 g as tetracarboxylic dianhydride (0.04 mol), 3.2 g (0.03 mol) of p-phenylenediamine as a diamine compound, 10.0 g (0.03 mol) of 2,2-bis (4-aminophenyl) hexafluoropropane, and the above formula Except that 20.9 g (0.04 mol) of the compound represented by (7) was used, a polyamic acid having a viscosity of 1.18 dl / g (this was referred to as “polyamic acid (PA-9)” in the same manner as in Synthesis Example 1. To obtain 51.3 g.

Synthesis Example 10 (Synthesis of polyamic acid)
As the diamine compound, 4.9 g (0.045 mol) of p-phenylenediamine, 5.0 g (0.015 mol) of 2,2-bis (4-aminophenyl) hexafluoropropane and the above formula (7) are used. 42. A polyamic acid having a logarithmic viscosity of 1.13 dl / g (referred to as “polyamic acid (PA-10)”) in the same manner as in Synthesis Example 9 except that 20.9 g (0.04 mol) of the compound was used. 3 g was obtained.

Synthesis Example 11 (Synthesis of polyamic acid)
As the diamine compound, 6.4 g (0.03 mol) of 2,2′-dimethyl-4,4′-diaminobiphenyl, 9.6 g of 4,4′-diamino-2,2′-bis (trifluoromethyl) biphenyl ( 0.03 mol) and a polyamic acid having a logarithmic viscosity of 1.24 dl / g (this is the same as in Synthesis Example 9) except that 20.9 g (0.04 mol) of the compound represented by the above formula (7) was used. 46.3 g of “polyamic acid (PA-11)”.

Synthesis Example 12 (Synthesis of polyamic acid)
As the diamine compound, 5.9 g (0.03 mol) of 4,4-diaminodiphenylmethane, 13.4 g (0.04 mol) of 2,2-bis (4-aminophenyl) hexafluoropropane, and the above formula (7) are used. A polyamic acid having a logarithmic viscosity of 1.33 dl / g (referred to as “polyamic acid (PA-12)”) in the same manner as in Synthesis Example 9 except that 15.7 g (0.03 mol) of the above compound was used. 50.3 g was obtained.

Synthesis Example 13 (Synthesis of polyamic acid)
As the diamine compound, 7.9 g (0.04 mol) of 4,4-diaminodiphenylmethane, 9.6 g (0.03 mol) of 4,4′-diamino-2,2′-bis (trifluoromethyl) biphenyl and the above formula Except that 15.7 g (0.03 mol) of the compound represented by (7) was used, a polyamic acid having a logarithmic viscosity of 1.09 dl / g (hereinafter referred to as “polyamic acid (PA-13)” was obtained in the same manner as in Synthesis Example 9. 43.8 g).

Synthesis Example 14 (Synthesis of polyamic acid)
As tetracarboxylic dianhydride, 9.8 g (0.045 mol) of 2,3,5,6-benzenetetracarboxylic dianhydride, 4,4- (2,2-hexafluoroisopropylidene) diphthalic anhydride 6.7 g (0.015 mol) and 2,3,5-tricarboxycyclopentyl acetic acid dianhydride 9.0 g (0.04 mol), and p-phenylenediamine 6.5 g (0.06 mol) as a diamine compound And a polyamic acid having a logarithmic viscosity of 1.06 dl / g in the same manner as in Synthesis Example 1 except that 20.9 g (0.04 mol) of the compound represented by the above formula (7) was used. PA-14) ”) was obtained.

Synthesis Example 15 (Synthesis of polyamic acid)
2,3,5,6-benzenetetracarboxylic dianhydride 6.5 g (0.03 mol), 4,4- (2,2-hexafluoroisopropylidene) diphthalic anhydride as tetracarboxylic dianhydride A logarithmic viscosity of 1.36 dl was obtained in the same manner as in Synthesis Example 14 except that 13.3 g (0.03 mol) and 2,3,5-tricarboxycyclopentylacetic acid dianhydride 9.0 g (0.04 mol) were used. / G of polyamic acid (referred to as “polyamic acid (PA-15)”) 24.3 g.

Comparative Example 1 (Synthesis of polyamic acid)
As tetracarboxylic dianhydride, 10.9 g (0.05 mol) of 2,3,5,6-benzenetetracarboxylic dianhydride and 11.2 g of 2,3,5-tricarboxycyclopentylacetic acid dianhydride ( 0.05 mol), 8.7 g (0.08 mol) of p-phenylenediamine as a diamine compound, and 10.5 g (0.02 mol) of the compound represented by the above formula (7) were added to N-methyl-2- It was dissolved in 185 g of pyrrolidone and reacted at 40 ° C. for 4 hours. The reaction solution was then poured into a large excess of methyl alcohol to precipitate the reaction product. Thereafter, it was washed with methyl alcohol and dried at 40 ° C. under reduced pressure for 15 hours to obtain 24.7 g of a polyamic acid having a logarithmic viscosity of 1.32 dl / g (referred to as “polyamic acid (PA-16)”). It was.

Comparative Example 2
As tetracarboxylic dianhydride, 13.1 g (0.06 mol) of 2,3,5,6-benzenetetracarboxylic dianhydride and 1,2,3,4-cyclobutanetetracarboxylic dianhydride7. 8 g (0.04 mol), 4.3 g (0.04 mol) of p-phenylenediamine as a diamine compound, 5.9 g (0.03 mol) of 4,4-diaminodiphenylmethane, and the above formula (7) 15.7 g (0.03 mol) of the compound was dissolved in 185 g of N-methyl-2-pyrrolidone and reacted at 40 ° C. for 4 hours. The reaction solution was then poured into a large excess of methyl alcohol to precipitate the reaction product. Thereafter, it was washed with methyl alcohol and dried at 40 ° C. under reduced pressure for 15 hours to obtain 25.2 g of a polyamic acid having a logarithmic viscosity of 1.14 dl / g (referred to as “polyamic acid (PA-17)”). It was.

Comparative Example 3
As tetracarboxylic dianhydride, 19.6 g (0.1 mol) of 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 5.4 g (0.05 mol) of p-phenylenediamine as a diamine compound, 4.0 g (0.02 mol) of 4,4-diaminodiphenylmethane and 15.7 g (0.03 mol) of the compound represented by the above formula (7) were dissolved in 185 g of N-methyl-2-pyrrolidone. The reaction was carried out at 4 ° C. for 4 hours. The reaction solution was then poured into a large excess of methyl alcohol to precipitate the reaction product. Thereafter, it was washed with methyl alcohol and dried at 40 ° C. under reduced pressure for 15 hours to obtain 41.7 g of polyamic acid having a logarithmic viscosity of 1.03 dl / g (referred to as “polyamic acid (PA-18)”). It was.

Reference example 1
The polyamic acid (PA-1) obtained in Synthesis Example 1 is dissolved in an N-methyl-2-pyrrolidone / butyl cellosolve mixed solvent (weight ratio 50/50) to obtain polyethylene glycol diglycidyl ether (epoxy compound 1: molecular weight of about 400) was dissolved in 40 parts by weight of the polymer 100 to obtain a solution having a solid content concentration of 4% by weight. This solution was filtered using a filter having a pore size of 1 μm to prepare the vertical liquid crystal aligning agent of the present invention.
The vertical liquid crystal aligning agent is applied on a transparent conductive film made of an ITO film provided on one surface of a glass substrate having a thickness of 1 mm by applying the film-forming composition with a spinner and drying at 200 ° C. for 60 minutes. A film having a dry film thickness of 0.08 μm was formed.

  Next, after applying an epoxy resin adhesive containing aluminum oxide spheres having a diameter of 5.5 μm to the outer edges of the pair of transparent electrodes / transparent electrode substrates having the liquid crystal alignment film of the liquid crystal alignment film coated substrate, the liquid crystal alignment film The adhesive was cured by overlapping and pressing so that the surfaces were opposed. Next, a negative type liquid crystal (MLC-2038, manufactured by Merck & Co., Inc.) is filled between the substrates through the liquid crystal injection port, and then the liquid crystal injection port is sealed with an acrylic photo-curing adhesive, and polarizing plates are formed on both sides of the substrate. Were laminated to prepare a liquid crystal display element. With respect to the obtained liquid crystal display element, vertical alignment properties, voltage holding ratio and residual voltage were evaluated.

  Similarly, the liquid crystal aligning agent of the present invention prepared as described above is applied onto an ITO substrate having a thickness of 1.5 mm using a spinner, and a coating film is formed in the same manner as in the production of a liquid crystal display element. did. 8 μl of negative liquid crystal (MLC-2038, manufactured by Merck & Co., Inc.) is dropped on the obtained liquid crystal alignment film-formed substrate using a syringe with a needle tip diameter of 0.5 mm, and the alignment film when 50 seconds have elapsed after the dropping. And the liquid crystal contact angle was measured. The evaluation results are shown in Table 1. Since the liquid crystal aligning agent obtained by this invention has a low contact angle with a liquid crystal, it was confirmed that the liquid crystal wetting spreadability is good, and it has a high voltage holding ratio and a low residual voltage.

Reference Examples 2 to 47 , Examples 1 to 8, Comparative Examples 1 to 13
According to the prescription shown in the following table, the polyamic acid polymer and the epoxy group-containing compound (epoxy compounds 1 to 3) shown in the table are dissolved in an N-methyl-2-pyrrolidone / butyl cellosolve mixed solvent to obtain a solid content concentration of 4.0%. A liquid crystal aligning agent of the present invention was prepared by filtering the solution through a filter having a pore size of 1 μm. Using each of the thus prepared liquid crystal aligning agents, a film was formed on the substrate surface in the same manner as in Reference Example 1, and a liquid crystal display element was produced using the substrate on which the liquid crystal aligning film was formed. . Then, the contact angle with the liquid crystal, the vertical alignment, the voltage holding ratio, and the residual voltage were evaluated. The results are shown in Table 1.

Claims (4)

(I) The following formula (I-1)

Here, P ¹ and Q ¹ are tetravalent and divalent organic groups, respectively.
And / or (ii) the following formula (I-2)

Here, P ² and Q ² are tetravalent and divalent organic groups, respectively.
A vertical alignment type liquid crystal aligning agent containing a polymer composed of imide repeating units represented by:
P ¹ in the above formula (I-1) and P ² in the above formula (I-2) are each independently represented by the following formula (II-1 -1 ) or (II-1-2)

Here, at least one of A ¹ and A ² are off Tsu atom or a fluorinated alkyl group and the other is a hydrogen atom or an alkyl group,

Here, at least one of A ³ and A ⁴ is a fluorine atom or a fluorinated alkyl group, and the other is a hydrogen atom or an alkyl group.
The said liquid crystal aligning agent characterized by containing 1-50 mol% of tetravalent organic groups containing fluorine atom represented by these.
P ¹ in the above formula (I-1) and P ² in the above formula (I-2) are each independently represented by the following formula (IV-1)

Here, R ¹ , R ² , R ³ , R ⁴ and R ⁵ are each independently a monovalent organic group containing no hydrogen atom or fluorine atom,
The liquid crystal aligning agent of Claim 1 which contains at least 1 sort (s) of the tetravalent organic group represented by at least 10 mol%. Q ¹ in the above formula (I-1) and Q ² in the above formula (I-2) are each independently represented by the following formulas (V-1) and (V-2)

Here, R ⁶ is a divalent organic group having an alicyclic skeleton having 4 to 40 carbon atoms, and R ⁷ is an alkyl group having 10 to 20 carbon atoms and an alicyclic skeleton having 4 to 40 carbon atoms. X is a single bond, —O—, —CO—, —COO—, —OCO—, —NHCO—, —CONH—, —S—, a methylene group, 2 carbon atoms. An alkylene group of ˜6 and a phenylene group ,
The liquid crystal aligning agent of Claim 1 or 2 which contains 10-60 mol% of bivalent organic groups represented by these . Vertical liquid crystal display element characterized by having a vertical liquid crystal alignment film obtained from the vertical alignment type liquid crystal alignment agent according to any one of claims 1-3.