JP2001270988A - Composition for oriented liquid crystal film, oriented liquid crystal film, its manufacturing method, and holding substrate liquid crystal for and liquid crystal display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composition for an oriented liquid crystal film which can retain the orientation even by curing at a temperature as low as 120 deg.C-160 deg.C and does generate a flaw and a chip by rubbing, a oriented liquid crystal film which exhibits images of high quality capable of obtaining a pretilt angle of >=4 deg. necessary for the super-twisted nematic (STN) use even by curing at a temperature as low as <=160 deg.C by using the composition, its manufacturing method, holding substrates for liquid crystals and a holding device for liquid crystals which use the oriented liquid crystal film and exhibit images of high quality. SOLUTION: The composition for a oriented liquid crystal film comprises a polyimide or its precursor whose residue has a repeating unit represented by formula (I) (wherein W is a tetravalent organic group; and R is a divalent organic group), at least part of W being a residue of 3,3',4,4'-benzophenonetetracarboxylic anhydride and at least part of R being a residue represented by formula (II) (wherein R1 and R2 are each independently a monovalent group), the oriented liquid crystal film, its manufacturing method, the liquid crystal holding substrates for liquid crystal, and the liquid crystal display are described.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a composition for a liquid crystal alignment film for controlling the alignment of liquid crystal, a liquid crystal alignment film and a method for producing the same,
The present invention relates to a liquid crystal holding substrate and a liquid crystal display device.

[0002]

2. Description of the Related Art A conventional liquid crystal display device employs a display system typified by a twisted nematic display system by using a transparent electrode made of ITO (indium tin oxide) or the like for each opposing substrate. . A liquid crystal alignment film is provided on the transparent electrode, and a polyimide-based liquid crystal alignment film (JP-A-55-10180, JP-A-63-259).
No. 515) is used. These are those which are applied on a substrate and dried at 180 to 350 ° C.,
It is obtained by performing a rubbing treatment by forming a polyimide film by dehydration and ring closure.

[0003] In recent years, the market for liquid crystal panels thin and lightweight for mobile phones has been expanding, and the use of plastic substrates for that purpose has been expanding. Since the plastic substrate has a problem in heat resistance, the liquid crystal alignment film has 160
There is a demand for low-temperature curing characteristics of not more than ℃. On the other hand, the dehydration and ring closure of polyamic acid mainly occurs in a temperature range of 120 ° C. to 160 ° C., and it is said that a polyimide varnish which has been imidized in advance is more preferable when curing at a low temperature of 160 ° C. or lower. However, the polyimide varnish has a problem that scratches and scraping occur during rubbing.

[0004] US Patent No. 5,670,609 discloses that
A polyimide liquid crystal alignment film comprising pyromellitic dianhydride and 2,2′-bis (perfluoroalkoxy) benzidine has been proposed, but it is not stated that the film is curable at a low temperature of less than 180 ° C.

[0005]

SUMMARY OF THE INVENTION The present invention solves the drawbacks of the prior art and provides an alignment function even at a low temperature of 120.degree. C. or more and 160.degree. C. or less, and is free from scratches and scraping during rubbing. It is intended to provide a composition for a liquid crystal alignment film. Further, the present invention provides a liquid crystal alignment film composition that can obtain a pretilt angle of 4 ° or more required for super twisted nematic (hereinafter abbreviated as STN) use even at a low temperature curing of 160 ° C or less. An object of the present invention is to provide a liquid crystal alignment film capable of displaying a high quality image and a method for manufacturing the same. Further, the present invention provides a liquid crystal sandwiching substrate and a liquid crystal sandwiching device which show a high quality image by using the above liquid crystal alignment film.

[0006]

In order to solve the above problems, the present invention uses the following means. That is, (1) General formula (I)

Embedded image (Wherein, W represents a tetravalent organic group and R represents a divalent organic group), and at least a part of W in the repeating unit is 3,3 ′ , 4,
4′-benzophenone tetracarboxylic dianhydride residue, wherein at least a part of R in the repeating unit is represented by the general formula (II):

Embedded image (Wherein, R ¹ and R ² are each independently a monovalent group). A composition for a liquid crystal alignment film, comprising polyimide or a precursor thereof, which is a residue represented by the formula:

(2) Of W in the repeating unit,
The composition for a liquid crystal alignment film according to the above (1), wherein at least 30 mol% or more is a residue of 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride. (3) at least 3 of R's in the repeating unit
The composition for a liquid crystal alignment film according to the above (1) or (2), wherein 0 mol% or more is a residue represented by the general formula (II).

(4) A liquid crystal alignment film obtained by rubbing a polyimide film formed from the composition for a liquid crystal alignment film according to (1), (2) or (3). (5) The composition for a liquid crystal alignment film according to (1), (2) or (3) is dried or closed at a temperature of 120 ° C. or more and 160 ° C. or less to form a polyimide film, and then subjected to a rubbing treatment. Manufacturing method of alignment film.

(6) A liquid crystal sandwiching substrate comprising the liquid crystal alignment film according to (4) or the liquid crystal alignment film obtained by the production method according to (6). (7) A liquid crystal display device comprising the liquid crystal sandwiching substrate according to (6).

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The composition for a liquid crystal alignment film of the present invention comprises:
It contains polyimide or a polyimide precursor. This polyimide or polyimide precursor is preferably a tetracarboxylic dianhydride and a diamine compound preferably at 100 ° C. or less,
More preferably, it is obtained by reacting at 80 ° C. or lower. The term “polyimide precursor” refers to a substance which can be converted into a polyimide by ring closure, and generally includes a polyamic acid, a polyamic acid ester, a polyamic acid amide, a partially imidized product thereof, a polyimide precursor having a mixed structure thereof, and the like. Among them, polyamic acid, a partially imidized product thereof, and a mixture thereof are preferable. The polyimide and the polyimide precursor are preferably soluble in the solvent of the composition for a liquid crystal alignment film.

The polyimide or polyimide precursor used in the composition of the present invention has a repeating unit represented by the general formula (I) or a repeating unit as a precursor thereof. In the general formula (I), the tetravalent organic group represented by W is generally two acid anhydride groups (—CO—O—CO 2) of the tetracarboxylic dianhydride used as a raw material.
-), And the divalent organic group represented by R is generally a divalent compound of the diamine compound used as a raw material.
It is a residue excluding _two amino groups (-NH2).

In the present invention, at least some of the residues represented by W have a carbonyl group.
3 ', 4,4'-Benzophenonetetracarboxylic dianhydride residue. Thereby, good orientation can be exhibited even at the time of curing at a low temperature of 120 ° C. or more and 160 ° C. or less. In addition, at least a part of the diamine residue represented by R is a diamine having a 4,4′-diaminobiphenyl skeleton represented by the general formula (II). Good orientation characteristics can be exhibited even when the composition is not completely imidized by curing. That is, by having both structures together, the excellent effects of the present invention can be obtained.

In the present invention, in order to obtain even better orientation, 30 of the diamine residues represented by R
Preferably, at least mol% is represented by the general formula (II), more preferably at least 50 mol%. Examples of the monovalent group represented by R ¹ and R ² in the general formula (I) include a hydrogen atom, a fluorine atom, and a carbon atom having 1 to 10 carbon atoms.
An alkyl group, an alkoxy group having 1 to 10 carbon atoms, a perfluoroalkyl group having 1 to 10 carbon atoms, a perfluoroalkoxy group having 1 to 10 carbon atoms, etc., among which a hydrogen atom,-(CF ₂₎ n-CF ₃ or -O
_(CF 2) (is where n is an integer of 0 to 7) a group represented by n-CF ₃ are preferred. Preferred examples of the diamine compound giving the residue represented by the general formula (II) include 2,2
2′-bis (trifluoromethyl) -benzidine, 2,
2'-bis (trifluoromethoxy) -benzidine, 2
-Trifluoromethyl-benzidine, 2-trifluoromethoxy-benzidine, 2,2'-bis (pentafluoroethyl) -benzidine, 2,2'-bis (pentafluoroethoxy) -benzidine, 2-pentafluoroethyl-benzidine , 2-pentafluoroethoxy-benzidine, 2,2'-bis (heptafluoropropane) -benzidine, 2,2'-bis (heptafluoroproxy)
-Benzidine, 2-heptafluoropropane-benzidine, 2-heptafluoroproxy-benzidine, 2-pentafluoroethoxy-benzidine, 2,2'-bis (heptadecafluorooctane) -benzidine, 2,
2′-bis (heptadecafluorooctoxy) -benzidine, 2-heptadecafluorooctane-benzidine,
2-heptadecafluorooctoxy-benzidine and the like. These are used alone or in combination of two or more. In order to exhibit a high pretilt angle of 4 ° or more for STN applications, the content of the residue of the fluorine-containing diamine compound is preferably at least 30 mol%, more preferably at least 50%.

Other diamine compounds that can be used in the present invention include 2,3,5,6-tetramethyl-1,4-phenylenediamine, 2,3,5,6
-Tetraethyl-1,4-phenylenediamine, 2,
5, -dimethyl-1,4-phenylenediamine, 2,
5, -dimethyl-1,3-phenylenediamine, 2,
5, -diethyl-1,4-phenylenediamine, 2,
5, -diethyl-1,3-phenylenediamine, 1,4
Phenylenediamine, 2,4,6-trimethyl-1,
3-phenylenediamine, 2,4,6-triethyl-
1,3-phenylenediamine, 1,3-phenylenediamine, 2,2′-dimethyl-4,4′-diaminobiphenyl, 4,4′-diaminodiphenylsulfone, 3,4′-
Diaminodiphenyl sulfone, 3,3′-diaminodiphenyl sulfone, 4,4′-diaminodiphenyl sulfide, 3,4′-diaminodiphenyl sulfide, 3,
3′-diaminodiphenyl sulfide, bis (4- (3
-Aminophenoxy) phenyl) sulfone, bis (4-
(4-aminophenoxy) phenyl) sulfone, bis (4- (4-aminophenoxy) phenyl) sulfide, bis (4- (3-aminophenoxy) phenyl) sulfide, 4,4′-diaminodiphenyl ether,
3,4′-diaminodiphenyl ether, 3,3′-diaminodiphenyl ether, 2,4′-diaminodiphenyl ether, 4,4′-diaminodiphenylmethane,
2,4'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 3,3'-diaminodiphenylmethane, 2-bis (4- (4-aminophenoxy) phenyl) propane, 2,2-bis (4- (4 -Aminophenoxy) phenyl) hexafluoropropane, 2,2-bis (4- (3-aminophenoxy) phenyl) hexafluoropropane, 2,2-bis (4-aminophenoxy) hexafluoropropane, 1,6-hexa Methylenediamine, 1,8-octamethylenediamine, 1,10
-Decamethylenediamine, 1,12-dodecamethylenediamine, azelaic acid dihydrazide, sebacic acid dihydrazide, 2,6-naphthoic acid dihydrazide, 2,4'-
Diamino-3-methyl-stearylphenyl ether,
2,4′-diamino-3-methyl-laurylphenyl ether, 2,4′-diamino-3-methyl-palmitylphenyl ether, 2,4′-diamino-1-octyloxybenzene, 2,2-bis ( 4- (4-aminophenoxy) phenyl) octane, 2,2-bis (4- (4
-Aminophenoxy) phenyl) tridecane, 2,2-
Bis (4- (4-aminophenoxy) phenyl) pentadecane, bis (4- (4-aminobenzoyloxy) benzoic acid) octane, bis (4- (4-aminobenzoyloxy) benzoic acid) decane, bis (4- (4-aminobenzoyloxy) benzoic acid) dodecane, bis (4- (4
-Aminobenzoyloxy) benzoic acid) methylcyclohexane, bis (4- (4-aminobenzoyloxy) benzoic acid) methane, bis (4- (3-aminobenzoyloxy) benzoic acid) butane, diaminosiloxane, 1,3
-Di (3-aminopropyl) -1,1,3,3-tetramethyldisiloxane and the like, which may be used alone or in combination of two or more.

In the present invention, the tetracarboxylic dianhydride that gives W in the general formula (I) includes 3,3 ′,
4,4′-benzophenonetetracarboxylic dianhydride is used as an essential component, and in addition, 1,2,3,4-butanetetracarboxylic dianhydride, 1,2,4,5-pentanetetracarboxylic dianhydride Anhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-
Cyclopentanetetracarboxylic dianhydride, 1,2,2
4,5-cyclohexanetetracarboxylic dianhydride, bicyclo (2,2,2) oct-7-ene-2,3,5
6-tetracarboxylic dianhydride, 3,4-dicarboxy-1,2,3,4-tetrahydro-1-naphthalene succinic dianhydride, pyromellitic dianhydride, 3,3 ′,
4,4′-biphenyltetracarboxylic dianhydride, 3,
3 ', 4,4'-diphenyl ether tetracarboxylic dianhydride, 2,2-bis (3,4-dicarboxylphenyl) hexafluoropropanoic dianhydride, octyl succinic dianhydride, dodecyl succinic dianhydride Anhydride, octylmalonic dianhydride, dimethylene bistrimellitate dianhydride, trimethylene bis trimellitate dianhydride, tetramethylene bis trimellitate dianhydride, pentamethylene bis trimellitate dianhydride, hexa Methylene bis trimellitate dianhydride, octamethylene bis trimellitate dianhydride, decamethylene bis trimellitate dianhydride, dodecamethylene bis trimellitate dianhydride, hexadecamethylene bis trimellitate dianhydride, Methylene-1,2-bis (1,3-dihydro-
1,3-dioxo-5-isobenzofuranyl) diether, propylene-1,3-bis (1,3-dihydro-
(1,3-dioxo-5-isobenzofuranyl) diether, 1,3-cyclohexanebistrimellitate dianhydride, 1,4-cyclohexanebistrimellitate dianhydride, 1,2-cyclohexanebistrimellitate acid Dianhydrides and the like can be used alone or in combination of two or more.

3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, when used in an amount of 30 mol% or more of the total W, can maintain a stable pretilt angle even at a low temperature curing of 120 ° C. to 160 ° C. 50 mol%
This is more preferable because the effect is even higher.

In the present invention, the ratio of the total number of moles of the diamine compound to the number of moles of the acid dianhydride is preferably in the range of 0.8 to 1.2, more preferably 1.0. Can be done. As the inert solvent that can be used at this time, it is not necessary to dissolve all of the above monomers, but one that dissolves the generated polyamic acid is preferable. For example, N-methyl-2-pyrrolidone, N ,
N-dimethylformamide, N, N-dimethylacetamide, γ-butyrolactone, ε-caprolactone, γ-
Examples thereof include caprolactone, γ-valerolactone, dimethyl sulfoxide, 1,4-dioxane, and cyclohexanone, and two or more of these may be used in combination.

In the present invention, the solid content concentration of the composition for a liquid crystal alignment film is preferably in the range of 1 to 20% by weight, more preferably 3 to 15% by weight. If the concentration is less than 1% by weight, the film thickness after application becomes too thin to obtain a good film in some cases. If the concentration exceeds 20% by weight, the viscosity becomes high. Coating characteristics tend to be poor.

Further, a solvent for improving the wettability to the printing medium can be added before or after the reaction. As these solvents, for example, ethyl cellosolov, ethyl cellosolov acetate, butyl cellosolov,
Butyl cellosolov acetate, xylene, toluene, 1
-Ethoxy-2-acetoxypropane, diisobutylketone, methyl-n-hexylketone and the like.

In the present invention, the composition containing the obtained polyimide precursor is preferably used as it is as a composition for a liquid crystal alignment film. However, if necessary, a composition containing a polyimide subjected to a ring-closing reaction may be used. Can be.
The ring closing reaction is performed by (a) a method of heating a polyimide precursor,
(Ii) A method in which a dehydrating agent and a dehydration ring-closing catalyst are added to a polyimide precursor such as polyamic acid to cause a ring-closing reaction, and if necessary, further heating is performed.

In the method (a) obtained by heating, the reaction temperature is preferably 130 to 170 ° C. When the reaction temperature is lower than 100 ° C., the dehydration ring-closure reaction does not proceed sufficiently, and when the reaction temperature exceeds 200 ° C., the thermal imidization and the decrease in molecular weight are observed. In the method (b), as the dehydrating agent, for example, acid anhydrides such as acetic anhydride, propionic anhydride, and trifluoroacetic anhydride can be used. The amount of the dehydrating agent used is preferably 1 to 20 mol per 1 mol of the repeating unit of the polyimide precursor such as polyamic acid.

As the dehydration ring-closing catalyst, for example, tertiary amines such as pyridine, triethylamine, collidine and lutidine can be used. The amount of the dehydration ring-closing catalyst used is preferably 0.5 to 10 mol per 1 mol of the dehydrating agent. In addition, as an organic solvent used for the dehydration ring closure reaction, an organic solvent used for synthesizing a polyamic acid can be exemplified.

Examples of the method of forming the polyimide film as the liquid crystal alignment film include a spin coating method, an immersion method, a printing method, and a spraying method. The polyimide film is formed by a printing method which does not require a photolithography step and can be easily formed by patterning. The production of a resin film by a flexographic printing machine which easily retains the varnish and transfers a large amount to a printing medium is more preferable. The printing medium used at this time includes a plastic substrate, a glass substrate, a silicon wafer, and the like.

The composition for a liquid crystal alignment film of the present invention comprises a silane coupling agent for improving the adhesion to glass.
A coupling agent such as a titanium coupling agent can be added. Examples of the coupling agent include γ-
Aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltripropoxysilane, γ-aminopropyltributoxysilane,
γ-aminoethyltriethoxysilane, γ-aminoethyltrimethoxysilane, γ-aminoethyltripropoxysilane, γ-aminoethyltributoxysilane, γ-
Examples include aminobutyltriethoxysilane, γ-aminobutyltrimethoxysilane, γ-aminobutyltripropoxysilane, γ-aminobutyltributoxysilane, and the like, and examples of the titanium coupling agent include γ-aminopropyltrimethoxysilane. Ethoxytitanium, γ-aminopropyltrimethoxytitanium, γ-aminopropyltripropoxytitanium, γ-aminopropyltributoxytitanium, γ-aminoethyltriethoxytitanium, γ-aminoethyltrimethoxytitanium, γ-aminoethyltripropoxytitanium , Γ-aminoethyltributoxytitanium, γ-aminobutyltriethoxytitanium, γ-aminobutyltrimethoxytitanium, γ-aminobutyltripropoxytitanium, γ-aminobutyltributoxytitanium,
And the like. These may be used in combination of two or more. The amount used at this time is preferably 0.5 to 5% by weight of the resin.

When the composition for a liquid crystal alignment film of the present invention contains a polyimide precursor, a polyimide film is formed by heating, drying, and dehydration ring closure. The heating temperature is generally 100 to 3
It is 50 degreeC, Preferably it is 110-230 degreeC. Further, for a plastic substrate, it is preferable to heat in the range of 120 to 160 ° C. The heating time is usually 1 minute to 6 hours, preferably 1 minute to 3 hours. The thickness of the polyimide film to be formed is usually 0.01 to 3 μm, preferably 0.02 to 0.1 μm. The composition for a liquid crystal alignment film of the present invention can be applied, for example, as an insulating film for a semiconductor or a color filter protective film for a liquid crystal.

The composition for a liquid crystal alignment film of the present invention is applied onto a transparent electrode such as ITO (Indium Tin Oxide) or a transparent substrate such as glass or plastic film with silicon nitride by using a spinner, a printing machine or the like. If necessary, the resin film can be subjected to heat curing treatment. As the liquid crystal display element substrate on which the liquid crystal alignment film is formed, for example, other than glass such as fluorinate glass having good smoothness, polyethylene terephthalate,
Polyester such as polybutylene terephthalate, epoxy resin, phenol resin, polyimide, polycarbonate, polysulfone, polyether sulfone, polyetherimide, acetylcellulose, polyamino acid ester, heat-resistant resin such as aromatic polyamide, polystyrene,
Polyacrylate, polymethacrylate,
Plastic films formed from vinyl polymers such as polyacrylamide, polyethylene, and polypropylene, fluorine-containing resins such as polyvinylidene fluoride, and denatured products thereof, and the like can be given.

The polyimide film formed on the substrate is used as a liquid crystal alignment film by subjecting the surface to a rubbing treatment. A liquid crystal display device can be obtained by a known method using the liquid crystal sandwiching substrate having the liquid crystal alignment film obtained as described above. Liquid crystal sandwiching substrate As the liquid crystal sandwiched between the substrates, a material suitable for each of TN, STN, and TFT is used depending on the type of the liquid crystal display element.

A spacer is used to secure a gap between both alignment films. Glass fiber,
Glass beads, plastic beads, metal oxide particles such as alumina and silica are used.

The liquid crystal display device of the present invention is not particularly limited except that it has the liquid crystal alignment film. As a structure of the liquid crystal display device, (1) a display pixel, a TFT, and an electrode group are formed on a substrate, and a liquid crystal alignment film is formed on the substrate via an insulating layer. (2) a liquid crystal display device provided with a deflecting means for changing a deflection characteristic for changing an optical characteristic of the liquid crystal layer, wherein the liquid crystal alignment film is formed of the composition for a liquid crystal alignment film; A) a pixel electrode is formed on a substrate by a scanning signal electrode, a video signal electrode, a pixel electrode, a common electrode, and a TFT, and a liquid crystal alignment film is disposed on the substrate via an insulating layer, and the liquid crystal layer is sandwiched between the substrates. The electrode group is configured to apply an electric field substantially parallel to the substrate surface to the liquid crystal layer, and the electrode group includes a deflecting unit that changes a deflection characteristic that changes an optical characteristic of the liquid crystal layer. Was In crystal display device, the liquid crystal alignment film wherein liquid crystal display device which is formed by a liquid crystal alignment film composition.

[0030]

Embodiments of the present invention will be described below. Synthesis Example 1 N-methyl-2-pyrrolidone (322.36 g) was added to a four-neck separable flask equipped with a thermometer, a stirrer, a cooling tube, and a nitrogen inlet tube, and 2,2′-bis (trifluoro) was added thereto. Methyl) -benzidine (32.023 g, 0.1 mol) was added and dissolved, followed by pyromellitic dianhydride.
15.268 g (0.07 mol), 3,3 ′, 4,4′-
Benzophenone tetracarboxylic dianhydride 9.607
After adding 2 g (0.03 mol) and stirring at room temperature for 16 hours, the viscosity was adjusted to obtain a 15% by weight polyamic acid varnish. The viscosity was 3500 in an E-type viscometer (25 ° C.)
mPa · s. After adding 1% by weight of the resin content of γ-aminopropyltriethoxysilane to the obtained polyamic acid varnish, the mixture was diluted with N-methyl-2-pyrrolidone and butyl cellosolve to obtain 4% by weight of polyamic acid varnish. The viscosity of the obtained polyimide varnish A is 3
It was 0 mPa · s.

Synthesis Example 2 334.54 g of N-methyl-2-pyrrolidone was added to a 4-neck separable flask equipped with a thermometer, a stirrer, a cooling tube and a nitrogen inlet tube, and 2,2'-bis was added thereto. (Trifluoromethyl) -benzidine (32.023 g, 0.1 mol) was added and dissolved, followed by pyromellitic dianhydride.
10.906 g (0.05 mol), 3,3 ′, 4,4′-
Benzophenone tetracarboxylic dianhydride 16.11
After adding 1 g (0.05 mol) and stirring at room temperature for 16 hours, the viscosity was adjusted to obtain a 15% by weight polyamic acid varnish. The viscosity was 4000 mPa · s. After adding 1% by weight of the resin content of γ-aminopropyltriethoxysilane to the obtained polyamic acid varnish, the mixture was diluted with N-methyl-2-pyrrolidone and butyl cellosolve to obtain 4% by weight of polyamic acid varnish. The viscosity of the obtained polyimide varnish B was 34 mPa · s.

Synthesis Example 3 334.54 g of N-methyl-2-pyrrolidone was added to a 4-neck separable flask equipped with a thermometer, a stirrer, a condenser tube and a nitrogen inlet tube, and 2,2'-bis was added thereto. After adding and dissolving 32.024 g (0.1 mol) of (trifluoromethyl) -benzidine, 32.222 g of 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride was obtained.
(0.1 mol), and the mixture was stirred at room temperature for 16 hours, and then the viscosity was adjusted to obtain a 15% by weight polyamic acid varnish. The viscosity was 3500 mPa · s. After adding 1% by weight of the resin content of γ-aminopropyltriethoxysilane to the obtained polyamic acid varnish, the mixture was diluted with N-methyl-2-pyrrolidone and butyl cellosolve to obtain 4% by weight of polyamic acid varnish. The viscosity of the obtained polyimide varnish C was 32 mPa · s.

Synthesis Example 4 182.38 g of N-methyl-2-pyrrolidone was added to a four-neck separable flask equipped with a thermometer, a stirrer, a condenser tube and a nitrogen inlet tube, and 2,2'-bis (tri Fluoromethoxy) -benzidine 28.179 g (0.08 mol), 4,4′-diaminodiphenyl ether 4.00
After adding 5 g (0.02 mol) and dissolving,
32.222 g (0.1 mol) of 3 ', 4,4'-benzophenonetetracarboxylic dianhydride was added, and 16
After stirring for an hour, the viscosity was adjusted to obtain a 15% by weight polyamic acid varnish. The viscosity was 3500 mPa · s. After adding 1% by weight of the resin content of γ-aminopropyltriethoxysilane to the obtained polyamic acid varnish, the mixture was diluted with N-methyl-2-pyrrolidone and butyl cellosolve to obtain 4% by weight of polyamic acid varnish.
The viscosity of the obtained polyimide varnish D was 28 mPa · s.

Comparative Synthesis Example 1 To a four-neck separable flask equipped with a thermometer, a stirrer, a cooling tube and a nitrogen introducing tube, 182.38 g of N-methyl-2-pyrrolidone was added, and 2,2'-bis ( 17.612 g (0.05 mol) of trifluoromethyl) -benzidine, 5.40 of 4,4′-diaminodiphenyl ether
After adding 7 g (0.05 mol) and dissolving,
3 ', 4,4'-biphenyltetracarboxylic dianhydride
After adding 32.222 g (0.01 mol) and stirring at room temperature for 16 hours, the viscosity was adjusted to obtain a 15% by weight polyamic acid varnish. The viscosity was 3500 mPa · s. After adding 1% by weight of the resin content of γ-aminopropyltriethoxysilane to the obtained polyamic acid varnish, the mixture was diluted with N-methyl-2-pyrrolidone and butyl cellosolve to obtain 4% by weight of polyamic acid varnish.
The viscosity of the obtained polyamic acid varnish E is 20 mPa · s.
Met.

Comparative Synthesis Example 2 In a four-neck separable flask equipped with a thermometer, a stirrer, a cooling pipe and a nitrogen inlet pipe, p-phenylenediamine 1
0.814 g (0.1 mol) is dissolved in 154.29 g of N-methyl-2-pyrrolidone. To this, 16.414 g (0.1 mol) of 2,2-bis (3,4-dicarboxylphenyl) hexafluoropropanoic acid dianhydride was added, and after stirring at room temperature for 16 hours, the viscosity was adjusted.
% By weight of a polyamic acid varnish was obtained. The viscosity of the obtained polyamic acid varnish was 2500 mPa · s. After adding 1% by weight of the resin content of γ-aminopropyltriethoxysilane to the obtained polyamic acid varnish, N-methyl-2-varnish was added to obtain 4% by weight of polyamic acid varnish.
It was diluted with pyrrolidone and butyl cellosolve. The viscosity of the obtained polyamic acid varnish F was 20 mPa · s.

Comparative Synthesis Example 3 In a four-necked separable flask equipped with a thermometer, a stirrer, a cooling tube and a nitrogen inlet tube, 4,4'-diaminodiphenyl ether 20 in 225.74 g of N-methyl-2-pyrrolidone 20 After adding and dissolving 0.024 g (0.1 mol), 32.222 g (0.1 mol) of 1,2,3,4-butanetetracarboxylic dianhydride was added, and the mixture was stirred at room temperature for 16 hours. The viscosity was adjusted to obtain a polyamic acid varnish of 15% by weight. The viscosity was 2000 mPa · s. After adding 1% by weight of the resin content of γ-aminopropyltriethoxysilane to the obtained polyamic acid varnish, the mixture was diluted with N-methyl-2-pyrrolidone and butyl cellosolve to obtain 4% by weight of polyamic acid varnish.
The viscosity of the obtained polyamic acid varnish G is 23 mPa · s.
Met.

Example 1 The varnish A obtained in Synthesis Example 1 was spin-coated on a glass substrate on which an ITO electrode was formed, and heated on a hot plate at 80 ° C. for 2 minutes and in an oven at 160 ° C. for 90 minutes. Thus, a polyimide film having a thickness of 60 nm was obtained. The substrates were combined so that the orientation direction of the polyimide became 180 ° by rubbing treatment, and the periphery was sealed. The cell gap was 25 μm with the liquid crystal sealed, and a polyethylene terephthalate film was interposed. Nematic liquid crystal ZLI-2293 (trade name, manufactured by Merck) was injected between the substrates by a vacuum impregnation method. An isotropic treatment was performed at 110 ° C. for 20 minutes, which is a phase transition temperature of 85 ° C. or higher, to obtain a pretilt angle evaluation liquid crystal display element (hereinafter abbreviated as anti-parallel cell). The prepared liquid crystal display element had good orientation, and the pretilt angle was evaluated by a crystal rotation method to be 8.7 °.

Similarly, varnish A is spin-coated on a glass substrate on which an ITO electrode is formed, and hot plate 8
Heat treatment at 0 ° C. for 2 minutes—oven at 140 ° C. for 90 minutes, and separately for hot plate at 80 ° C. for 2 minutes—oven 120
A heat treatment at 90 ° C. for 90 minutes is carried out, and
Was obtained, and the orientation and the pretilt angle were evaluated. The results are summarized in Table 1.

Next, the varnish A was heated on a hot plate at 80 ° C. for 2 minutes—on an oven at 160 ° C. for 90 minutes on the substrate on which the ITO electrodes were formed so as to form 640 × 200 dots in the same manner as described above. A rubbing process is performed so that the orientation direction of the polyimide is 240 ° twist, and a cell gap is set to 6 μm in a liquid crystal sealed state, and a liquid crystal is injected. A display element was manufactured. The liquid crystal display element is 64
It can be driven with 0x200 dots, no domain is generated,
The contrast was good and the display quality was high.

Similarly, varnish A is spin-coated on a substrate on which a 640 × 200 dot ITO electrode is formed, and
A heat treatment at a hot plate of 80 ° C. for 2 minutes—an oven at 140 ° C. for 90 minutes, and a heat treatment at a temperature of a hot plate at 80 ° C. for 2 minutes—an oven at 120 ° C. for 90 minutes are separately performed to obtain a film thickness of 60
Then, a 240 ° twist cell was rubbed, a cell was assembled, and liquid crystal was injected to produce a liquid crystal display device. Table 2 shows the results of the display characteristics.

Example 2 The varnish B obtained in Synthesis Example 2 was spin-coated on a glass substrate on which an ITO electrode was formed, and heated at 80 ° C. for 2 minutes to 160 ° C. for 90 minutes in the same manner as in Example 1. , 80 ℃ 2
Heat treatment at 140 ° C for 90 minutes, 80 ° C for 2 minutes -1
A heat treatment at 20 ° C. for 90 minutes is separately performed to obtain a film thickness of 60 n
m was obtained. An anti-parallel cell was manufactured in the same manner as in Example 1. The results of orientation and pretilt angle are:
The results are shown in Table 1. Similarly, varnish B was 640 × 200
Spin coating is performed on the substrate on which the dot ITO electrodes are formed, and the same as in Example 1, 80 ° C. for 2 minutes and −160 ° C. 90
Heat treatment at 80 ° C. for 2 minutes to 140 ° C. for 90 minutes, and heat treatment at 80 ° C. for 2 minutes to 120 ° C. for 90 minutes to obtain a polyimide film having a thickness of 60 nm.
The 0 ° twist cell was subjected to a rubbing treatment, a cell was assembled, a liquid crystal was injected, and a liquid crystal display device was produced. Table 2 shows the results of the display characteristics.

Example 3 The varnish C obtained in Synthesis Example 3 was spin-coated on a glass substrate on which an ITO electrode was formed, and heated at 80 ° C. for 2 minutes to 160 ° C. for 90 minutes in the same manner as in Example 1. , 80 ℃ 2
Heat treatment at 140 ° C for 90 minutes, 80 ° C for 2 minutes -1
A heat treatment at 20 ° C. for 90 minutes is separately performed to obtain a film thickness of 60 n
m was obtained. An anti-parallel cell was manufactured in the same manner as in Example 1. The results of orientation and pretilt angle are:
The results are shown in Table 1. Similarly, varnish C was 640 × 200
Spin coating is performed on the substrate on which the dot ITO electrodes are formed, and the same as in Example 1, 80 ° C. for 2 minutes and −160 ° C. 90
Heat treatment at 80 ° C. for 2 minutes to 140 ° C. for 90 minutes, and heat treatment at 80 ° C. for 2 minutes to 120 ° C. for 90 minutes to obtain a polyimide film having a thickness of 60 nm.
The 0 ° twist cell was subjected to a rubbing treatment, a cell was assembled, a liquid crystal was injected, and a liquid crystal display device was produced. Table 2 shows the results of the display characteristics.

Example 4 The varnish D obtained in Synthesis Example 4 was spin-coated on a glass substrate on which an ITO electrode was formed, and heated at 80 ° C. for 2 minutes to 160 ° C. for 90 minutes in the same manner as in Example 1. , 80 ℃ 2
Heat treatment at 140 ° C for 90 minutes, 80 ° C for 2 minutes -1
A heat treatment at 20 ° C. for 90 minutes is separately performed to obtain a film thickness of 60 n
m was obtained. An anti-parallel cell was manufactured in the same manner as in Example 1. The results of orientation and pretilt angle are:
The results are shown in Table 1.

Similarly, varnish D is spin-coated on a substrate on which a 640 × 200 dot ITO electrode is formed, and
Heat treatment at 80 ° C. for 2 minutes to 160 ° C. for 90 minutes, heat treatment at 80 ° C. for 2 minutes to 140 ° C. for 90 minutes, as in Example 1.
A heat treatment at 80 ° C. for 2 minutes to 120 ° C. for 90 minutes is separately performed to obtain a polyimide film having a thickness of 60 nm, a rubbing treatment is performed on a 240 ° twist cell, a cell is assembled, a liquid crystal is injected, and a liquid crystal display element is manufactured. did. Table 2 shows the results of the display characteristics.

Comparative Example 1 The varnish E obtained in Comparative Synthesis Example 1 was spin-coated on a glass substrate on which an ITO electrode was formed, and heated at 80 ° C. for 2 minutes to 160 ° C. for 90 minutes as in Example 1. Processing, 80
A heat treatment at 140 ° C. for 90 minutes and a heat treatment at 80 ° C. for 2 minutes to 120 ° C. for 90 minutes were separately performed to give a film thickness of 6
A polyimide film having a thickness of 0 nm was obtained, but the product treated at 120 ° C. had poor orientation. Table 1 summarizes the results of the orientation and the pretilt angle. Similarly, the varnish E is spin-coated on the substrate on which the 640 × 200 dot ITO electrode is formed, and heat-treated at 80 ° C. for 2 minutes to 160 ° C. for 90 minutes and 80 ° C. for 2 minutes as in Example 1. A heat treatment at 90 ° C. for 90 minutes and a heat treatment at 80 ° C. for 2 minutes to 120 ° C. for 90 minutes were separately performed to obtain a polyimide film having a thickness of 60 nm.
The rubbing treatment was performed on the twist cell, the cell was assembled, and liquid crystal was injected to produce a liquid crystal display device. Since the pretilt angle was low, it could not be used for a liquid crystal display element for STN. Table 2 shows the results of the display characteristics.

Comparative Example 2 The varnish F obtained in Comparative Synthesis Example 2 was spin-coated on a glass substrate on which an ITO electrode was formed, and heated at 80 ° C. for 2 minutes to 160 ° C. for 90 minutes in the same manner as in Example 1. Processing, 80
A heat treatment at 140 ° C. for 90 minutes and a heat treatment at 80 ° C. for 2 minutes to 120 ° C. for 90 minutes were separately performed to give a film thickness of 6
A 0 nm polyimide film was obtained. An anti-parallel cell was manufactured in the same manner as in Example 1. As a result, streaks occurred in the polyimide film during the rubbing treatment. Table 1 summarizes the results of the orientation and the pretilt angle. Similarly, varnish F was added to 640
Spin coating is performed on the substrate on which the × 200 dot ITO electrode is formed, and the same as in Example 1, -16 ° C. for 2 minutes
Heat treatment at 0 ° C. for 90 minutes, 80 ° C. for 2 minutes, −140 ° C. 90
Heat treatment at 80 ° C. for 2 minutes and heat treatment at −120 ° C. for 90 minutes to obtain a polyimide film having a thickness of 60 nm, rubbing the 240 ° twist cell, assembling the cell, injecting liquid crystal, A liquid crystal display device was manufactured. Since the pretilt angle was low, it could not be used for a liquid crystal display element for STN. Table 2 summarizes the results of the display characteristics.
Shown in

Comparative Example 3 The varnish G obtained in Comparative Synthesis Example 2 was spin-coated on a glass substrate on which an ITO electrode was formed, and heated at 80 ° C. for 2 minutes to 160 ° C. for 90 minutes in the same manner as in Example 1. Processing, 80
A heat treatment at 140 ° C. for 90 minutes and a heat treatment at 80 ° C. for 2 minutes to 120 ° C. for 90 minutes were separately performed to give a film thickness of 6
A polyimide film having a thickness of 0 nm was obtained, but the product treated at 120 ° C. had poor orientation. An anti-parallel cell was manufactured in the same manner as in Example 1. Table 1 summarizes the results of the orientation and the pretilt angle. Similarly, the varnish G is spin-coated on the substrate on which the 640 × 200 dot ITO electrode is formed, and heat-treated at 80 ° C. for 2 minutes to 160 ° C. for 90 minutes and 80 ° C. for 2 minutes as in Example 1. A heat treatment at 90 ° C. for 90 minutes and a heat treatment at 80 ° C. for 2 minutes to 120 ° C. for 90 minutes were separately performed to obtain a polyimide film having a film thickness of 60 nm and 240 ° C.
The twist cell was rubbed, the cell was assembled, and liquid crystal was injected to produce a liquid crystal display device. Since the pretilt angle was low, it could not be used for a liquid crystal display element for STN. Table 2 shows the results of the display characteristics.

[0048]

[Table 1]

[0049]

[Table 2]

[0050]

According to the composition for a liquid crystal alignment film of the present invention,
A good alignment function can be obtained even under low-temperature curing conditions of 120 ° C. to 160 ° C., and a high-quality liquid crystal display device free from scratches and scraping during rubbing can be provided. In addition, the liquid crystal alignment film of the present invention and the method for producing the same use the liquid crystal alignment film composition described above and are required to be used as a super twisted nematic (STN) 4 ° even at a low temperature of 160 ° C. or lower.
It is possible to show a high-quality image that can obtain the above pretilt angle. Further, the liquid crystal holding substrate and the liquid crystal holding device of the present invention show a high quality image by using the above liquid crystal alignment film.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Naoki Okuda 4-3-1, Higashicho, Hitachi City, Ibaraki Prefecture Hitachi Chemical DuPont Microsystems Co., Ltd. Yamazaki Development Center F-term (reference) MB01 4F071 AA60 AF35 AH12 AH19 BA02 BB02 BC02 4J002 CM041 GP00 GQ00

Claims (7)

[Claims] 1. A compound of the general formula (I) (Wherein, W represents a tetravalent organic group and R represents a divalent organic group), and at least a part of W in the repeating unit is 3,3 ′ , 4,
4′-benzophenonetetracarboxylic dianhydride, wherein at least a part of R in the repeating unit is a compound represented by the general formula (II): (Wherein, R ¹ and R ² are each independently a monovalent group). A composition for a liquid crystal alignment film, comprising polyimide or a precursor thereof, which is a residue represented by the formula: 2. The composition for a liquid crystal alignment film according to claim 1, wherein at least 30 mol% or more of W in the repeating unit is a residue of 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride. object. 3. The composition for a liquid crystal alignment film according to claim 1, wherein at least 30 mol% or more of R in the repeating unit is a residue represented by the general formula (II). 4. A liquid crystal alignment film obtained by rubbing a polyimide film formed from the composition for a liquid crystal alignment film according to claim 1, 2 or 3. 5. A composition for a liquid crystal alignment film according to claim 1, 2 or 3, which is dried or closed at a temperature of 120 ° C. or more and 160 ° C. or less to form a polyimide film and then rubbing. Manufacturing method. 6. A liquid crystal sandwiching substrate comprising a liquid crystal alignment film according to claim 4 or a liquid crystal alignment film obtained by the production method according to claim 5. 7. A liquid crystal display device comprising the liquid crystal holding substrate according to claim 6.