JP3267347B2 - Liquid crystal alignment agent - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal aligning agent. More specifically, the present invention relates to a liquid crystal aligning agent having good coatability during printing.

[0002]

2. Description of the Related Art Conventionally, a nematic liquid crystal having a positive dielectric anisotropy has a sandwich structure with a substrate having a transparent electrode having a liquid crystal alignment film made of polyimide or the like, and the major axis of the liquid crystal molecules is 90 to 270 between the substrates. 2. Description of the Related Art A liquid crystal display element (TN, STN type display element) having a TN or STN type liquid crystal cell which is twisted continuously is known. This T
The alignment of the liquid crystal in the N, STN type liquid crystal display element is formed by a liquid crystal alignment film subjected to a rubbing process.
This liquid crystal alignment film is applied using a printing method. If the film thickness unevenness during printing is large, specifically, the film thickness is ± 50 °.
There is a problem that the above-mentioned variation affects display characteristics and electric characteristics.

[0003]

An object of the present invention is to provide a liquid crystal aligning agent having a novel composition. Another object of the present invention is to solve the above-mentioned conventional problems and to provide a liquid crystal aligning agent having small thickness unevenness during printing. Still other objects and advantages of the present invention will become apparent from the following description.

[0004]

According to the present invention, the above objects and advantages of the present invention are as follows: (A) The reaction product of a tetracarboxylic dianhydride and a diamine.
At least one polymer, and (B) .gamma.-butyrolactone and N- methyl-2-pyrrolidone containing and N- methyl-2-pyrrolidone content selected from the a polyamic acid and soluble polyimide thing 0.1 And a mixed solvent in the range of .about.50% by weight.

[0005] The liquid crystal aligning agent of the present invention comprises a specific polymer (A) and a specific mixed solvent (B). The polyamic acid of the polymer (A) is obtained by reacting a tetracarboxylic dianhydride with a diamine in a solvent. Such tetracarboxylic dianhydrides include, for example, butanetetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride 2,3,5-tricarboxycyclopentylacetic dianhydride, 3,5,6-tricarboxynorbornane-2-acetic 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, 5- (2,5-dioxotetrahydrofural) -3-methyl-3-cyclohexene-1,2-dicarboxylic dianhydride, bicyclo [2,
Aliphatic and alicyclic tetracarboxylic dianhydrides such as 2,2] -oct-7-ene-2,3,5,6-tetracarboxylic dianhydride; pyromellitic dianhydride 3,3 ', 4,
4'-benzophenonetetracarboxylic dianhydride, 3,
3 ', 4,4'-biphenylsulfonetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 3 , 3 ', 4,4'-biphenylethertetracarboxylic 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) diphenyl sulfone dianhydride,
4,4′-bis (3,4-dicarboxyphenoxy) 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 ( An aromatic tetracarboxylic dianhydride such as (triphenylphthalic acid) -4,4′-diphenylmethane dianhydride can be mentioned.

Of these, butanetetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentylacetic dianhydride, 5- (2, 5-dioxotetrahydrofural) -3-methyl-3-cyclohexene-1,2-dicarboxylic dianhydride, 1,3,3a, 4,5,9b-hexahydro-5-tetrahydro-2,5-dioxo- 3-Furanyl) -naphtho [1,2-c] -furan-1,3-dione is preferred.

As the diamine compound, for example, p
Phenylenediamine, m-phenylenediamine, 4,
4'-diaminodiphenylmethane, 4,4'-diaminodiphenylethane, 4,4'-diaminodiphenylsulfide, 4,4'-diaminodiphenylsulfone,
4'-diaminodiphenyl ether, 1,5-diaminonaphthalene, 3,3-dimethyl-4,4'-diaminobiphenyl, 4,4'-diaminobenzanilide, 3,4'-
Diaminodiphenyl ether, 3,3′-diaminobenzophenone, 3,4′-diaminobenzophenone,
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, 9,9-
Bis (4-aminophenyl) fluorene, 4,4′-methylene-bis (2-chloroaniline), 2,2 ′, 5,
5'-tetrachloro-4,4'-diaminobiphenyl,
2,2'-dichloro-4,4'-diamino-5,5'-dimethoxybiphenyl, 3,3'-dimethoxy-4,4'-
Aromatic diamines such as diaminobiphenyl; aromatic diamines having a heteroatom such as diaminotetraphenylthiophene; 1,1-metaxylylenediamine; 1,3-
Propanediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, 1,4-diaminocyclohexane, isophoronediamine, tetrahydrodicyclopentadienylenediamine, hexahydro-4, Aliphatic or alicyclic diamines such as 7-methanoindanylene dimethylene diamine, tricyclo [6,2,1,0 ^2.7 ] -undecylenedimethyl diamine, 4,4'-methylene bis (cyclohexylamine);

[0008]

Embedded image

(Wherein R is a hydrocarbon group having 1 to 12 carbon atoms such as a chain alkyl group such as a methyl group, an ethyl group or a propyl group, a cycloalkyl group such as a cyclohexyl group, or an aryl group such as a phenyl group). And p is 1 to 3,
q represents an integer of 1 to 20, respectively)

And the like. Of these, p-phenylenediamine, 4,4'-diaminodiphenylmethane, 4,4'-
Diaminodiphenyl ether, 2,2-bis [4- (4
-Aminophenoxy) phenyl] propane, 9,9-bis (4-aminophenyl) fluorene, 2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane, 2,2-bis (4-amino (Phenyl) hexafluoropropane is preferred. These can be used alone or in combination of two or more. These diamines may be used as they are, or may be used after being reduced again.

The above-mentioned organic solvent used in the reaction includes:
There is no particular limitation as long as it can dissolve the polyamic acid generated by the reaction. For example, γ-butyrolactone and N-methyl-2-pyrrolidone are preferably used. The amount of the organic solvent used is such that the total amount of the tetracarboxylic dianhydride and all the diamine compounds is 0.1 to 3 with respect to the total amount of the reaction solution.
Preferably, it is 0% by weight. The reaction temperature at this time is preferably 0 to 150 ° C, more preferably 0 to 100 ° C.

The use ratio of the tetracarboxylic dianhydride to the diamine compound is such that the acid anhydride group of the tetracarboxylic dianhydride is 0.2 to 1 equivalent of the amino group in the diamine compound.
To 2 equivalents, more preferably 0.3 to
1.2 equivalents.

The soluble polyimide used in the present invention is:
It is obtained by imidizing the above-mentioned polyamic acid by heating or in the presence of a dehydrating agent and an imidization catalyst. The reaction temperature when imidizing by heating is preferably 60 to 200 ° C, more preferably 100 to 17 ° C.
0 ° C. If the reaction temperature is lower than 60 ° C., the progress of the reaction is easily delayed, and if it exceeds 200 ° C., the molecular weight of the soluble polyimide may be greatly reduced. The reaction for imidization in the presence of a dehydrating agent and an imidization catalyst can be performed in the above-mentioned organic solvent. The reaction temperature is preferably always 0 to 180 ° C, more preferably 60 to 150 ° C.
° C. Acid anhydrides such as acetic anhydride, propionic anhydride, and trifluoroacetic anhydride can be used as the dehydrating agent. Further, as the imidation catalyst, for example, tertiary amines such as pyridine, collidine, lutidine, and triethylamine can be used, but are not limited thereto. The amount of the dehydrating agent used is preferably 1.6 to 20 mol per 1 mol of the repeating unit of the polyamic acid. The amount of the imidization catalyst used is preferably 0.5 to 10 mol per 1 mol of the dehydrating agent used.

The polyamic acid thus obtained,
Intrinsic viscosity of soluble polyimide [η _{in h} = (ln ηrel
/ C, C = 0.5 g / dl, 30 ° C., N-methyl-2-
In the following, the intrinsic viscosity is measured under the same conditions in pyrrolidone] is preferably 0.05 to 10 dl / g, more preferably 0.0 to 10 dl / g.
5 to 5 dl / g.

The organic solvent used as a reaction medium is in such an amount that a poor solvent such as alcohols, ketones, esters, ethers, halogenated hydrocarbons, and polymers that generate hydrocarbons are not precipitated. Can be used together. Such poor solvents include, for example, methyl alcohol,
Ethyl alcohol, isopropyl alcohol, cyclohexanol, ethylene glycol, propylene glycol, 1,4-butanediol, triethylene glycol, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, methyl acetate, ethyl acetate,
Butyl acetate, diethyl oxalate, diethyl malonate, diethyl ether, methyl cellosolve, ethyl cellosolve, ethylene glycol-n-propyl ether, ethylene glycol-i-propyl ether, butyl cellosolve, ethylene glycol dimethyl ether, ethylene glycol ethyl ether acetate, diethylene glycol dimethyl ether , Tetrahydrofuran, dichloromethane, 1,2-dichloroethane, 1,4-dichlorobutane, trichloroethane, chlorobenzene, o-dichlorobenzene, hexane, heptane, octane, benzene, toluene, xylene and the like.

The liquid crystal aligning agent of the present invention contains γ-butyrolactone and N-methyl-2-pyrrolidone and has a content of N-methyl-2-pyrrolidone of 0.1 to 50% by weight, preferably 1 to 40% by weight. It contains the mixed solvent (B) in the range of% by weight. When the content of N-methyl-2-pyrrolidone is 0.5.
When the content is less than 1% by weight, the variation of the film thickness exceeds ± 50 °, and when the content of N-methyl-2-pyrrolidone exceeds 50% by weight, the film thickness unevenness due to the film whitening increases. .

The mixed solvent (B) in the present invention may contain other solvents, if necessary, in addition to γ-butyrolactone and N-methyl-2-pyrrolidone. The content of such another solvent is preferably about 80% by weight or less based on the whole mixed solvent (B).

Examples of such other solvents include N, N-
Aprotic polar solvents such as dimethylacetamide, N, N-dimethylformamide, dimethylsulfoxide, tetramethylurea, hexamethylphosphoramide; m
Phenolic solvents such as cresol, xylenol, phenol and halogenated phenol; and the above-mentioned alcohols, ketones, esters, ethers, halogenated hydrocarbons and hydrocarbons.

Further, the liquid crystal aligning agent of the present invention can contain a functional silane-containing compound for the purpose of improving the adhesion between the polyamic acid and / or the soluble polyimide and the substrate.

Examples of the functional silane-containing compound include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 2-aminopropyltrimethoxysilane, 2-aminopropyltriethoxysilane, and N- (2-aminopropyltrimethoxysilane). Ethyl) -3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-ureidopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, N-ethoxycarbonyl-3 -Aminopropyltrimethoxysilane, N-ethoxycarbonyl-3-aminopropyltriethoxysilane, N-triethoxysilylpropyltriethylenetriamine, N-trimethoxysilylpropyltriethylenetriamine, 1
0-trimethoxyisyl-1,4,7-triazadecane, 10-triethoxysilyl-1,4,7-triazadecane, 9-trimethoxysilyl-3,6-diazanonyl acetate, 9-triethoxysilyl- 3,6-diazanonyl acetate, N-benzyl-3-aminopropyltrimethoxysilane, N-benzyl-3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, N-phenyl-3 -Aminopropyltriethoxysilane, N-bis (oxyethylene) -3-aminopropyltrimethoxysilane, N-bis (oxyethylene) -3-aminopropyltriethoxysilane and the like.

A liquid crystal display device obtained by using the liquid crystal aligning agent of the present invention can be manufactured, for example, by the following method. First, the liquid crystal aligning agent of the present invention is applied on the transparent conductive film side of the substrate provided with the transparent conductive film by printing, preferably at 80 to 200 ° C, more preferably at 120 to 200 ° C.
To form a coating film. This coating is usually 0.001 to 1 μm, preferably 0.005 to 0.5.
μm.

The coating film formed as described above is subjected to a rubbing treatment with a roll around which a cloth made of a synthetic fiber such as nylon is wound, thereby forming a liquid crystal alignment film. As the substrate, for example, a transparent substrate made of glass such as float glass or soda glass, or a plastic film such as polyethylene terephthalate, polybutylene terephthalate, polyether sulfone, or polycarbonate can be used.

As the transparent conductive film, a NESA film made of SnO ₂ , an ITO film made of In ₂ O ₃ —SnO ₂ and the like can be used. A method using a mask in advance is used. When applying the liquid crystal aligning agent,
In order to further improve the adhesiveness between the substrate and the transparent conductive film and the coating film, a functional silane-containing compound, titanate, or the like may be applied on the substrate or the transparent conductive film in advance.

The two substrates having the liquid crystal alignment film formed thereon are opposed to each other so that the rubbing directions are orthogonal or antiparallel, the peripheral portion between the substrates is sealed with a sealant, and the liquid crystal is filled. Then, the filling hole is sealed to form a liquid crystal cell, and the liquid crystal display element is formed by bonding both surfaces of the liquid crystal cell such that the polarization directions thereof coincide with or perpendicular to the rubbing direction of the liquid crystal alignment film of the substrate.

As the sealant, for example, an epoxy resin containing a hardening agent and aluminum oxide spheres as spacers can be used. As the liquid crystal, a nematic liquid crystal, a smectic liquid crystal, and among them, a liquid crystal that forms a nematic liquid crystal are preferable. For example, a Schiff base liquid crystal, an azoxy liquid crystal, a biphenyl liquid crystal, a phenylcyclohexane liquid crystal, an ester liquid crystal, and a terphenyl liquid crystal are preferable. Liquid crystals, biphenylcyclohexane-based liquid crystals, pyrimidine-based liquid crystals, dioxane-based liquid crystals, bicyclooctane-based liquid crystals, cubane-based liquid crystals, and the like are used. In addition, cholesteric liquid crystals such as cholesteryl chloride, cholesteryl nonaate, and cholesteryl carbonate, and trade names C-15, CB
-15 (Merck Ltd.) can also be used by adding a chiral agent or the like. In addition, ferroelectric liquid crystals such as p-decyloxybenzylidene-p-amino-2-methylbutylcinnamate can be used.

As a polarizing plate used outside the liquid crystal cell, a polarizing plate in which a polarizing film called an H film in which polyvinyl alcohol is stretched and oriented and iodine is absorbed and sandwiched by a cellulose acetate protective film, or the H film itself is used. And the like.

[0027]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. The thickness of the liquid crystal alignment film was measured using a stylus-type film thickness meter (Alpha Step), and the thickness on the liquid crystal alignment film applied surface and its variation were evaluated.

Synthesis Example 1 2,4.8 g of 2,3,5-tricarboxycyclopentylacetic acid dianhydride and 21.6 g of p-phenylenediamine were converted to γ.
-Butyrolactone / N-methyl-2-pyrrolidone = 50
/ 50 (weight ratio) of 988 g, and reacted at room temperature for 6 hours. The reaction mixture was then poured into a large excess of methanol, causing the reaction product to precipitate. Thereafter, the resultant was washed with methanol and dried at 40 ° C. under reduced pressure for 15 hours to obtain 60.2 g of polyamic acid Ia having an intrinsic viscosity of 1.44 dl / g.

Synthesis Example 2 30.0 g of the polyamic acid Ia obtained in Synthesis Example 1 was added to 5
It was dissolved in 70 g of γ-butyrolactone, 21.6 g of pyridine and 16.74 g of acetic anhydride were added, and an imidization reaction was performed at 120 ° C. for 3 hours. Next, the reaction solution was precipitated in the same manner as in Synthesis Example 1 to obtain 24.0 g of polyimide IIa having an intrinsic viscosity of 1.35 dl / g.

Synthesis Example 3 A polyamic acid Ib was obtained in the same manner as in Synthesis Example 1 except that 39.6 g of 4,4′-diaminodiphenylmethane was used as the diamine in Synthesis Example 1, and further synthesized using this polyamic acid Ib. An imidization reaction was carried out in the same manner as in Example 2 to obtain a polyimide IIb2 having an intrinsic viscosity of 1.16 dl / g.
2.2 g were obtained.

Synthesis Example 4 The same procedure as in Synthesis Example 1 was carried out except that the tetracarboxylic dianhydride was changed to 39.22 g of cyclobutanetetracarboxylic dianhydride, and the intrinsic viscosity was 1.26 dl / g.
50.5 g of polyamic acid Ic was obtained.

Synthesis Example 5 In Synthesis Example 1, tetracarboxylic dianhydride was changed to 1,3,
3a, 4,5,9b-Hexahydro-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-
c] Polyamic acid Id was obtained in the same manner as in Synthesis Example 1 except that 60.0 g of furan-1,3-dione was used, and an imidization reaction was carried out in the same manner as in Synthesis Example 2 using this polyamic acid Id. 22.2 g of polyimide IId having an intrinsic viscosity of 1.16 dl / g were obtained.

Synthesis Example 6 The procedure of Synthesis Example 1 was repeated, except that the tetracarboxylic dianhydride was changed to 43.6 g of pyromellitic dianhydride, and the intrinsic viscosity was 1.66 dl / g.
60.5 g of e were obtained.

Example 1 The polymer Ia obtained in Synthesis Example 1 was converted to γ-butyrolactone /
It was dissolved in N-methyl-2-pyrrolidone (= 95/5, weight ratio) to obtain a solution having a solid content of 5% by weight, and this solution was filtered through a filter having a pore size of 1 μm to prepare a liquid crystal aligning agent solution. This solution was applied on a transparent electrode surface on a glass substrate with a transparent electrode made of an ITO film using a liquid crystal alignment film coating printer, and dried at 180 ° C. for 1 hour. When the in-plane film thickness was measured using a stylus-type film thickness meter, a uniform film thickness was obtained with an average value of 600 ° and a variation of ± 25 °.

Examples 2 to 8 The same procedures as in Example 1 were carried out except that the polyamic acid and the soluble polyimide obtained in Synthesis Examples 2 to 6 were used to prepare a liquid crystal aligning agent having the solvent composition shown in Table 1. Printing was performed in the same manner. The in-plane film thickness was measured, and the results are shown in Table 1.

[0036]

[Table 1]

Comparative Example 1 Printing was performed in the same manner as in Example 1 except that the solvent was changed to γ-butyrolactone using the soluble polyimide IIa obtained in Synthesis Example 2, and the average value of the in-plane film thickness was obtained. Is 61
0 ° and the variation was as large as ± 80 °.

Comparative Example 2 Printing was performed in the same manner as in Example 1 except that the soluble polyimide IIa obtained in Synthesis Example 2 was used and the solvent was changed to N-methyl-2-pyrrolidone. The average value of the thickness was 600 ° and the variation was as large as ± 120 °.

[0039]

According to the liquid crystal alignment agent of the present invention, a liquid crystal alignment film having a small thickness unevenness at the time of printing and particularly suitable for a TN or STN type liquid crystal display device can be obtained. Further, the liquid crystal display device having a liquid crystal alignment film formed using the liquid crystal alignment agent of the present invention can provide SH (Su) by selecting a liquid crystal to be used.
per Homeotropic), ferroelectric and antiferroelectric liquid crystal display devices. Furthermore, a liquid crystal display device having an alignment film formed using the liquid crystal alignment agent of the present invention has excellent liquid crystal alignment and reliability, and can be effectively used for various devices, such as a desk calculator, a wrist watch, a table clock,
Used for display devices such as coefficient display boards, word processors, personal computers, and liquid crystal televisions.

────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Yusuke Tsuda 2--11-24 Tsukiji, Chuo-ku, Tokyo Japan Synthetic Rubber Co., Ltd. (72) Inventor Nobuo Bessho 2-11-24 Tsukiji, Chuo-ku, Tokyo Japan Synthetic Rubber Co., Ltd. (56) References JP-A-2-4224 (JP, A) JP-A-58-223149 (JP, A) JP-A-3-188449 (JP, A) JP-A-61-275352 ( JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) G02F 1/1337

Claims (4)

(57) [Claims] (A) at least one polymer selected from a polyamic acid and a soluble polyimide, which is a reaction product of a tetracarboxylic dianhydride and a diamine; and (B) γ-butyrolactone and N-methyl-2- liquid crystal aligning agent characterized that you applied by the content of the containing pyrrolidone and N- methyl-2-pyrrolidone mixed solvent is in the range of 0.1 to 50 wt%, Tona Risoshite printing method. 2. The mixed solvent further contains another solvent.
The other solvent is less than about 80% by weight of the total mixed solvent.
The liquid crystal aligning agent according to claim 1. 3. The method according to claim 2, wherein the other solvent is butyl cellosolve or ethyl.
The liquid crystal aligning agent according to claim 2, which is lucellosolve. 4. The method of claim 1, wherein the tetracarboxylic dianhydride is butanetate.
Lacarboxylic dianhydride, 1,2,3,4-cyclobutane
Toracarboxylic dianhydride, 2,3,5-tricarboxy
Clopentyl acetic acid dianhydride, 5- (2,5-dioxote)
Trahydrofural) -3-methyl-3-cyclohexene
-1,2-dicarboxylic dianhydride or 1,3,3a, 4,
5,9b-hexahydro-5-tetrahydro-2,5-di
Oxo-3-furanyl) -naphtho [1,2-c] furan
The liquid crystal aligning agent according to claim 1, which is -1,3-dione.