JPH09281502A - Formation of liquid crystal vertically oriented film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simply and efficiently form a liquid crystal vertically oriented film by applying a coating solution containing a polysiloxane solution prepared by heating a reaction mixture containing a specific silicone compound, an alcohol and oxalic acid up to a specific state on an electrode base plate and thermally setting at a specific temp. SOLUTION: The reaction mixture containing the silicon compounds A and B expressed by formulas, Si(OR)4 and R<1> Si(OR)3 , the alcohol expressed by a formula, R<2> CH2 OH, and oxalic acid is produced. In the formulas, R expresses a 1-5C alkyl group, R<1> expresses a 3-20C non-substituted alkyl group and R<2> expresses hydrogen atom or the like. And the reaction mixture is heated at 50-180 deg.C while keeping the concn. of SiO2 to 0.5-10wt.% and the absence of water until the remaining quantity of the silicon compounds A and B becomes <=5mol%. The coating solution containing the polysiloxane solution produced in this way is applied on the electrode base plate and the resultant coating film is thermally setted at 80-400 deg.C.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an improvement in a liquid crystal vertical alignment film on an electrode substrate in a liquid crystal display device formed from a polymer solution of an alkoxy group-containing silicon compound.

[0002]

2. Description of the Related Art A commonly used liquid crystal display device comprises a liquid crystal and two electrode substrates facing each other with the liquid crystal interposed therebetween. Conventionally, a method of providing a film on an electrode substrate in a liquid crystal display device has been known as an effective method for vertically aligning liquid crystal molecules in a liquid crystal display device, and this film is called a liquid crystal vertical alignment film. There is. As an improved liquid crystal vertical alignment film, several films using an alkoxy group-containing silane as a raw material have been proposed.

In Japanese Patent Laid-Open No. 61-117524, at least one of the two electrode substrates in contact with the liquid crystal layer is coated with an organometallic compound such as tetrabutoxytitanium and heat-cured. A liquid crystal vertical alignment film is disclosed in which a monoalkyltrialkoxysilane such as octadecyltriethoxysilane is coated on a base film and then heat cured. The publication further discloses that the liquid crystal vertical alignment film has vertical reproducibility with good reproducibility, and the underlayer film stabilizes the liquid crystal vertical alignment film and improves adhesion and heat resistance to a substrate. Is explained.

JP-A-57-42019 discloses that tetraethoxysilane, dimethyldimethoxysilane, etc.
A silane having four alkoxy groups is subjected to ordinary hydrolysis and condensation polymerization with an acid catalyst or the like to produce a silanol-containing oligomer, and a ratio of 0.17 to 10 moles is used for 1 mole of the oligomer and the alkoxy group-containing silane. A long-chain alkyl group such as octadecyltriethoxysilane and an alkoxy group-containing silane are added to a solvent such as ethyl cellosolve to prepare a coating solution, the coating solution is coated on an electrode substrate, and then the coating film is coated at 100 to 250 ° C. A method of forming a vertical alignment film by thermosetting is disclosed. The publication describes that the coating liquid has excellent coatability, the alignment ability does not decrease in the heating step, and the obtained alignment film has excellent alignment properties for various liquid crystals.

In JP-A-57-56819, a carboxylic acid such as acetic acid or formic acid is reacted with a halogenated silane such as tetrachlorosilane to produce silicon carboxylate, and unreacted acetic acid is removed by distillation under reduced pressure. A solution of a silanol oligomer is produced by reacting silicon carboxylic acid with an alcohol such as ethyl alcohol.
Add an alkylsilane such as octadecyltriethoxysilane or perfluoroalkylsilane to a ratio of 10 to 20 to
A coating solution is prepared by reacting at 80 ° C., this coating solution is applied to the surface of the electrode substrate, and the coating film is applied to 10
A method of forming a vertical alignment film by thermosetting at 0 to 350 ° C. is disclosed. The publication describes that this alignment film can vertically align any liquid crystal, and the alignment is stable and the display quality is high.

[0006]

However, the vertical alignment film or the method for forming the same has not been sufficiently improved. The formation of the vertical alignment film described in JP-A-61-117524 requires a step of forming a base film made of a thermosetting material of an organometallic compound, and requires two coating and heating operations. As the vertical alignment film thus formed, a film having a sufficient thickness cannot be obtained, pinholes are likely to occur in the film, and the film has a short electrical life.

According to the method for forming a vertical alignment film described in JP-A-57-42019, a film having a sufficient thickness can be obtained. Although this film does not have pinholes, the liquid crystal vertical alignment ability is maintained. It has poor properties and requires a hydrolysis step and a subsequent mixing step to produce the coating solution used to form this film, and the production method is not simple, and the storage stability of the obtained coating solution is stable. The sex is not enough.

In the method of forming a vertical alignment film described in JP-A-57-56819, hydrogen chloride produced as a by-product of the reaction of a chlorine-containing substance such as chlorosilane as a raw material is subjected to the vacuum distillation step as described above. It remains in the produced liquid, corrodes the surrounding metal, and causes harm to the manufacture of a liquid crystal display device which requires particularly high purity. Further, the manufacturing of the coating solution also requires other steps, the manufacturing method is not simple, the end point of the reaction is difficult to confirm, and it is difficult to manufacture the coating solution of constant quality.

According to the present invention, an electrode substrate of a liquid crystal display device is provided with
It is intended to easily and efficiently form a liquid crystal vertical alignment film excellent in vertical alignment property of liquid crystal, its reproducibility, heat resistance and uniformity, and to form such a liquid crystal vertical alignment film. It is intended to provide a stable coating solution as an industrial product to be supplied and an efficient method for producing the same.

[0010]

Means for Solving the Problems The coating liquid used for forming the liquid crystal vertical alignment film of the present invention is represented by the following general formula (1) Si (OR) ₄ ... (1) (wherein R represents an alkyl group having 1 to 5 carbon atoms) and a silicon compound (A) represented by the following general formula (2) R ¹ Si (OR) ₃ (2) (wherein R ¹ represents an alkyl group having 3 to 20 carbon atoms, which is unsubstituted or has a fluorine atom substituent) , And R are the same as above.) And a silicon compound (B) represented by the following general formula (3) R ² CH ₂ OH. (3) (wherein R ² represents a hydrogen atom or an unsubstituted or substituted alkyl group having 1 to 12 carbon atoms). Coal (C) and oxalic acid (D) were added to the silicon compound (B) with respect to 1 mol of the silicon compound (A).
In a ratio of 0.05 to 0.43 mol, in a ratio of 0.5 to 100 mol of alcohol (C) to 1 mol of all alkoxy groups contained in silicon compound (A) and silicon compound (B), and silicon. A reaction mixture containing oxalic acid (D) in an amount of 0.2 to 2 moles based on 1 mole of all alkoxy groups contained in the compound (A) and the silicon compound (B) is formed, and the reaction mixture is formed therein. 0.5 converted from the silicon atom of
While maintaining the SiO ₂ concentration of 10% by weight and the absence of water, the total amount of the silicon compound (A) and the silicon compound (B) in the reaction mixture is 50 to 50 mol% until the total residual amount becomes 5 mol% or less. It consists of a solution of polysiloxane obtained by heating at 180 ° C.

The method for forming a liquid crystal vertical alignment film according to the present invention comprises applying the above-mentioned coating solution on the surface of an electrode substrate and thermally curing the coating film obtained by this application at 80 to 400 ° C. The liquid crystal vertical alignment film is formed in close contact with the surface of the electrode substrate. The polysiloxane solution is transparent and contains no gelled polysiloxane. Although a large amount of alcohol (C) and a relatively large amount of oxalic acid (D) coexist, the silicon compound (A) and the silicon compound (B) are heated in the reaction mixture in the absence of water. Is not generated by condensation of a hydrolyzate of the silicon compound (A) and the silicon compound (B). When a polysiloxane is produced from an alkoxysilane by a hydrolysis method in an alcohol solvent, turbidity occurs in the liquid as the hydrolysis proceeds, or a non-uniform polysiloxane is likely to be produced. It doesn't happen.

The above-mentioned polysiloxane according to the present invention has a complicated chemical structure and is difficult to specify, but it is probably an intermediate product produced by the reaction of the silicon compound (A) and the silicon compound (B) with oxalic acid (D). Since the alcohol (C) acts on the above to cause the polymerization to proceed, a silicon compound (A having a branched structure, a polymerization degree enough to form a solution, and a relatively uniform structure) It is considered that a polycondensate of polysiloxane of (1) and a silicon compound (B) is produced.

By heating the coating film containing the solution of the polysiloxane coated on the electrode substrate, the volatile components are removed from the coating film, and the curing reaction of the polysiloxane proceeds in the coating film. An insoluble film is formed that adheres to the substrate surface and has excellent vertical orientation.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Examples of the alkyl group R contained in the general formulas (1) and (2) include methyl, ethyl,
Propyl, butyl, pentyl and the like can be mentioned, and preferred examples of the silicon compound (A) include tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane,
Tetrabutoxysilane etc. are mentioned. Among these, tetramethoxysilane and tetraethoxysilane are particularly preferable. These may be used alone or in combination of two or more.

Alkyl group R contained in the general formula (2)
Examples of ¹ include unsubstituted alkyl groups such as hexyl, heptyl, octyl, dodecyl, hexadecyl, octadecyl, and trifluoropropyl, heptafluoropentyl, heptafluoroisopentyl, tridecafluorooctyl, heptadecafluorodecyl, and the like. And an alkyl group having a fluorine atom substituent. Preferred examples of the silicon compound (B) include hexyltrimethoxysilane, hexyltriethoxysilane, heptyltrimethoxysilane, heptyltriethoxysilane, octyltrimethoxysilane, octyltriethoxysilane, dodecyltrimethoxysilane and dodecyltriethoxysilane. , Hexadecyltrimethoxysilane, hexadecyltriethoxysilane, octadecyltrimethoxysilane,
An unsubstituted alkyltrialkoxysilane such as octadecyltriethoxysilane, the following general formula (4) CF ₃ (CF ₂ ) _n CH ₂ CH ₂ Si (OR) ₃ ... (4) (however, n represents an integer of 0 to 17, and R represents 1 to
Represents an alkyl group having 5 carbon atoms. ) Trifluoropropyltrimethoxysilane, trifluoropropyltriethoxysilane, heptafluoropentyltrimethoxysilane, heptafluoropentyltriethoxysilane, tridecafluorooctyltrimethoxysilane, tridecafluorooctyltriethoxysilane, heptadeca fluoro decyl trimethoxysilane, heptadecafluoro linear alkyl trialkoxysilane having a fluorine atom substituent such as decyl triethoxysilane and heptafluoro isopentanol trimethoxysilane _{[(CF 3) 2 CFCH 2 CH} 2 Si (OCH 3) ₃ ] and other branched-chain alkyltrialkoxysilanes having a fluorine atom substituent. These silicon compounds may be used alone or in combination of two or more.

Examples of the unsubstituted alkyl group R ² contained in the general formula (3) are methyl, ethyl, propyl,
Butyl, pentyl, hexyl, heptyl, octyl and the like, and examples of the alkyl group R ² having a substituent include hydroxymethyl, methoxymethyl, ethoxymethyl, hydroxyethyl, methoxyethyl, ethoxyethyl and the like. Preferred alcohol (C)
Examples of include methanol, ethanol, propanol, n-butanol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, and the like. These silicon compounds may be used alone or in combination of two or more. Of these, ethanol is particularly preferable.

A homogeneous polysiloxane solution cannot be obtained from the reaction mixture containing 0.43 mol or more of the silicon compound (B) per mol of the silicon compound (A). And from the reaction mixture using 0.05 mol or less of the silicon compound (B) to 1 mol of the silicon compound (A),
A film showing vertical alignment cannot be obtained. Silicon compound (A)
0.05 to 0.25 of the silicon compound (B) with respect to 1 mol.
It is particularly preferred to use a molar amount.

If an amount of alcohol less than 0.5 mol is used per mol of all alkoxy groups contained in the silicon compound (A) and the silicon compound (B), it takes a long time to form the polysiloxane. The obtained polysiloxane-containing liquid does not form a film having high hardness. On the other hand, if more than 100 mol of alcohol is used per mol of all the alkoxy groups contained in the silicon compound (A) and the silicon compound (B), the resulting polysiloxane-containing liquid will lack the SiO ₂ concentration. However, it requires concentration before application and is not efficient. It is particularly preferable to use 1 to 50 mol of the alcohol (C) with respect to 1 mol of all the alkoxy groups contained in the silicon compound (A) and the silicon compound (B).

When oxalic acid (D) is used in an amount of less than 0.2 mol based on 1 mol of all alkoxy groups contained in the silicon compound (A) and the silicon compound (B), the obtained polysiloxane-containing liquid is In addition to not being able to obtain a film exhibiting vertical orientation, the hardness of the obtained film is low. On the contrary, when oxalic acid (D) is used in an amount of more than 2 mol per mol of all alkoxy groups contained in the silicon compound (A) and the silicon compound (B), the resulting polysiloxane-containing liquid is relatively Since it contains a large amount of oxalic acid (D), a film having the desired performance cannot be obtained from such a liquid. It is particularly preferable to use 0.25 to 1 mol of oxalic acid (D) with respect to 1 mol of all alkoxy groups contained in the silicon compound (A) and the silicon compound (B).

To prepare a solution of polysiloxane, the above silicon compound (A), silicon compound (B), alcohol (C) are used.
Other than oxalic acid (D), if desired, for example, 2 to 20 mol% of the above silicon compound (A) and silicon compound (B) were not used with respect to 1 mol of the silicon compound (A). You may use alkoxysilane together as a modifier. Examples of preferred modifying agents include phenyltrimethoxysilane, phenyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-glycidoxypropyl. Trimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ
-Trialkoxysilanes such as methacryloxypropyltrimethoxysilane and γ-methacryloxypropyltriethoxysilane, and dialkoxysilanes such as dimethyldimethoxysilane and dimethyldiethoxysilane. These modifiers can lower the temperature for curing the coating on the electrode substrate and improve the adhesion of the film to the electrode substrate.

The reaction mixture containing the silicon compound (A), the silicon compound (B), the alcohol (C) and the oxalic acid (D) can be obtained by mixing these or by further adding the above-mentioned modifying agent to them. Can be formed. No water was added to the reaction mixture.
This reaction mixture is preferably heated as a solution-like reaction mixture. For example, oxalic acid (D) is added to alcohol (C) in advance to form an alcohol solution of oxalic acid, and then the solution and silicon compound are added. It is preferable to heat as a solution-like reaction mixture obtained by mixing (A), the silicon compound (B), the above-mentioned modifying agent and the like. Usually, in the reaction mixture of the silicon compound (A), the silicon compound (B), the alcohol (C) and the oxalic acid (D) in the above ratio, the silicon atom contained in the reaction mixture is converted into SiO ₂ and converted to 0.
It is contained in a concentration of 5 to 10% by weight. Also in the case of the reaction mixture containing the above-mentioned modifying agent, the silicon atom contained in this is changed to S.
The above-mentioned modifying agent is contained so as to have a concentration of 0.5 to 10% by weight in terms of iO ₂ . And during the heating of these reaction mixtures, these reaction mixtures are maintained at the above SiO ₂ concentration and the absence of water. This heating can be performed at a liquid temperature of 50 to 180 ° C. in a normal reactor, and preferably, for example, in a closed vessel or under reflux so that evaporation or volatilization of the liquid does not occur from the reactor. Be seen.

If the heating for producing the polysiloxane is carried out at a temperature lower than 50 ° C., a liquid having turbidity or insoluble matter is likely to be produced.
It is carried out at a higher temperature, and the higher the temperature, the shorter the time required for completion. However, heating above 180 ° C is inefficient with no additional benefit. There is no particular limitation on the heating time, for example, at 50 ° C. for about 8 hours,
Under reflux at 8 ° C., about 3 hours is sufficient, and usually when the remaining amount of the silicon compound (A) and the silicon compound (B) becomes 5 mol% or less with respect to the total charged amount. Heating is stopped. The total amount of the silicon compound (A) and the silicon compound (B) used is 5
The polysiloxane-containing liquid that remains in an amount of more than mol% is applied to the surface of the electrode substrate and then the coating film is heat-cured at 80 to 400 ° C., resulting in pinholes in the obtained film, or A film having sufficient hardness cannot be obtained.

The polysiloxane solution obtained by the above heating can be used as it is as a coating solution in the next coating step, but if desired, the solution obtained by concentrating or diluting it can be used as a coating solution. The liquid obtained by substituting the solvent of 1) can be used as a coating liquid, or the liquid obtained by mixing with a desired additive can be used as a coating liquid. Examples of this additive include solid inorganic fine particles such as colloidal fine particles, and other metal salts and metal compounds, which are convenient for adjusting the hardness of the film, the adhesion to the electrode substrate, the refractive index, and the like. Is.

The coating liquid used in the coating step is preferably a liquid containing therein 0.5 to 10% by weight of silicon atoms derived from the transparent solution of polysiloxane as calculated as SiO _2. When the SiO ₂ concentration is less than 0.5% by weight, the thickness of the film formed by one coating tends to be thin, and when this concentration is higher than 10% by weight, the storage stability of this coating solution is insufficient. It's easy to do. S of this coating liquid
The iO ₂ concentration is particularly preferably 2 to 8% by weight.

The above polysiloxane solution can be applied onto the electrode substrate by a conventional method such as a dipping method, a spin coating method, a brush coating method, a roll coating method or a flexographic printing method. The coating film formed on the electrode substrate may be heat-cured as it is, but prior to this, it is dried at room temperature to 80 ° C., preferably 50 to 80 ° C., and then 8
It is heated at 0 to 400 ° C, preferably 100 to 350 ° C. About 5 to 60 minutes is sufficient as the heating time. When the heating temperature is lower than 80 ° C., the hardness and chemical resistance of the obtained coating are likely to be insufficient. Thermal curing at a temperature higher than 350 ° C., particularly higher than 400 ° C. is not preferable because the vertical alignment performance is deteriorated. These heatings can be performed by a conventional method, for example, using a hot plate, an oven, a belt furnace or the like.

The thickness of the cured film is usually 100 to 2000.
Adjusted to Å. If the film thickness is less than 100Å, pinholes are likely to be formed, and the liquid crystal display device having the film is liable to suffer from deterioration of current-carrying stability and liquid crystal display defects. Meanwhile 2000
If it is thicker than Å, the uniformity of the surface of the film is deteriorated and cracks are likely to occur in the film.

[0027]

EXAMPLES Solutions of the polysiloxanes of the Examples and Comparative Examples were prepared and the stability of the solutions and the performance of the membranes obtained from them were tested. Example 1 Ethanol 5 in a 4-neck reaction flask equipped with a reflux tube.
Add 2.8 g, and add oxalic acid 2 to this ethanol with stirring.
An ethanol solution of oxalic acid was prepared by adding 0.0 g little by little. The solution is then heated to its reflux temperature and 21.8 g of tetraethoxysilane and 4.9 g of octadecyltriethoxysilane are added to the solution under reflux.
Was added dropwise. Even after the dropping is completed, heat under reflux for 5
After continuing for a period of time, the mixture was cooled and 75 g of butyl cellosolve was added to prepare a polysiloxane solution (L-1) having a SiO ₂ concentration of 4% by weight.

When this solution was analyzed by gas chromatography, no alkoxysilane monomer was detected. Example 2 Ethanol 5 in a 4-neck reaction flask equipped with a reflux tube.
2.3 g of oxalic acid was added to this ethanol with stirring.
An ethanol solution of oxalic acid was prepared by adding 0.5 g little by little. The solution is then heated to its reflux temperature and 21.8 g of tetraethoxysilane and tridecafluorooctyltrimethoxysilane [CF ₃ (CF ₂ ) ₅ CH ₂ CH ₂ Si (OCH ₃ ) _{3 are} added to this solution under reflux. ]
5.5 g of the mixture was added dropwise. After the dropping, heating was continued under reflux for 5 hours and then cooled, and butyl cellosolve 75 g was added.
Was added to prepare a solution of polysiloxane having a SiO ₂ concentration of 4% by weight (L-2).

When this solution was analyzed by gas chromatography, no alkoxysilane monomer was detected. Example 3 Ethanol 5 in a 4-neck reaction flask equipped with a reflux tube.
2.6 g of oxalic acid was added to this ethanol with stirring.
An ethanol solution of oxalic acid was prepared by adding 0.5 g little by little. The solution is then heated to its reflux temperature and 21.8 g of tetraethoxysilane and tridecafluorooctyltrimethoxysilane [CF ₃ (CF ₂ ) ₅ CH ₂ CH ₂ Si (OCH ₃ ) _{3 are} added to this solution under reflux. ]
A mixture of 2.7 g and octadecyltriethoxysilane 2.5 g was added dropwise. After completion of the dropping, heating was continued under reflux for 5 hours and then cooled, and 75 g of butyl cellosolve was added to prepare a polysiloxane solution (L-3) having a SiO ₂ concentration of 4% by weight.

When this solution was analyzed by gas chromatography, no alkoxysilane monomer was detected. Example 4 Ethanol 4 was added to a 4-neck reaction flask equipped with a reflux tube.
Add 9.7 g, and add oxalic acid 2 to this ethanol with stirring.
An ethanol solution of oxalic acid was prepared by adding 0.0 g little by little. The solution is then heated to its reflux temperature and 19.4 g of tetraethoxysilane and tridecafluorooctyltrimethoxysilane [CF ₃ (CF ₂ ) ₅ CH ₂ CH ₂ Si (OCH ₃ ) _{3 are} added to this solution under reflux. ]
10.9 g of the mixture was added dropwise. After completion of the dropping, heating was continued under reflux for 5 hours and then cooled, and butyl cellosolve 75 was added.
A solution of polysiloxane (L-4) having a SiO ₂ concentration of 4% by weight was prepared by adding g.

When this solution was analyzed by gas chromatography, no alkoxysilane monomer was detected. Comparative Example 1 Ethanol 6 was added to a 4-neck reaction flask equipped with a reflux tube.
4.9 g, tetraethoxysilane 21.8 g, and tridecafluorooctyltrimethoxysilane [CF ₃ (CF ₂ ).
5.6 g of ₅ CH ₂ CH ₂ Si (OCH ₃ ) ₃ ] was added and mixed uniformly. Then, 7.6 g of water and 0.1 g of nitric acid as a catalyst were added to this solution, and after stirring and mixing for 30 minutes, 75 g of butyl cellosolve was added to the solution of polysiloxane having a SiO ₂ concentration of 4% by weight (L- 5)
Was prepared.

Comparative Example 2 Ethanol 6 was added to a 4-neck reaction flask equipped with a reflux tube.
5.5 g, tetraethoxysilane 21.8 g and octadecyltriethoxysilane 5.0 g were added and uniformly mixed. Next, 7.6 g of water and 0.
After adding 1 g and stirring and mixing for 30 minutes, add 75 g of butyl cellosolve to obtain 4 wt% SiO ₂
A solution of polysiloxane having a concentration (L-6) was prepared.

Comparative Example 3 Ethanol 6 was added to a 4-neck reaction flask equipped with a reflux tube.
2.7 g, tetraethoxysilane 19.4 g and trideca
Fluorooctyltrimethoxysilane [CF_Three(CF_Two)
_FiveCH_TwoCH_TwoSi (OCH_Three)_Three] 10.9g was added and
Mixed together. Then 6.9 g of water and a catalyst were added to this solution.
0.1 g of nitric acid was added, and after stirring and mixing for 30 minutes,
4% by weight by adding 75 g of butyl cellosolve
SiO _Two A solution of polysiloxane having a concentration (L-
7) was prepared.

Comparative Example 4 Ethanol 6 was added to a 4-neck reaction flask equipped with a reflux tube.
2.7 g and 19.4 g of tetraethoxysilane were added and mixed with stirring. Next, 6.9 g of water and 0.1 g of nitric acid as a catalyst were added to this solution, and after stirring and mixing for 30 minutes, tridecafluorooctyltrimethoxysilane [CF] was added.
₃ (CF ₂ ) ₅ CH ₂ CH ₂ Si (OCH ₃ ) ₃ ] 10.9 g
Was added and mixed uniformly. A solution of polysiloxane having a SiO ₂ concentration of 4% by weight (L-8) was prepared by adding 75 g of butyl cellosolve.

Example 5 The polysiloxane solutions (L-1) to (L-8) described above were left to stand in a glass container at 23 ° C. for 3 months in a sealed state. During that time, the presence or absence of turbidity or precipitation generated in the solution was observed, and the results shown in Table 1 were obtained. In the table, ○ indicates that no change was observed at 3 months after the above exposure, △ indicates cloudiness at 1 month after the above exposure, and × indicates 2 weeks after the above exposure. It means that cloudiness occurred within. (L-6) produced a white precipitate in 7 days,
(L-7) became cloudy when the solution was prepared, and (L-8)
Produced cloudiness in 7 days. In the same table, the amount of the silicon compound (B) with respect to the amount of the silicon compound (A) used for preparing the solution is shown in a molar ratio.

[0036]

[Table 1] Table 1 Solution Mor ratio Stability Film formability L-1 0.11 ○ ○ L-2 0.11 ○ ○ L-3 0.11 ○ ○ L-4 0.25 ○ ○ L-5 0.11 △ ○ L-6 0.11 × △ L- 7 0.25 × ×L-8 0.25 × △ The results shown in Table 1 are the solutions of the polysilixane of the examples.
Are all good, whereas the hydrolysis method of Comparative Example
(L-5) to (L-6) polysiloxane prepared by
All of the solutions in Table 1 show poor stability.

Example 6 The conductive material of indium-tin oxide (ITO) and the electrode plate made of a glass plate covering the conductive material were coated on the glass plate (L-1) to (L-8). A siloxane solution was applied by a spin coater and then dried at 80 ° C. to form a coating film on the glass plate, and the surface of the coating film was observed to test the film forming properties of these solutions. The results are shown in Table 1. In the table, ◯ indicates that the coating film is uniform, Δ indicates that pinholes are partially generated in the coating film, and × indicates that the coating film is repelled.

The results shown in Table 1 are (L-6) to Comparative Example.
It is shown that the solution of the polysiloxane (L-8) has not only sufficient stability but also insufficient film forming property. Example 7 After the test of Example 6, the coating is applied at the temperature given in Table 2 to 6
By heating for 0 minutes, a thermosetting film was formed on the electrode substrate.

Next, two electrode substrates were bonded together with the surface having the above-mentioned thermosetting film inside, with a spacer of 50 μm sandwiched between them, and the internal void formed by this was used as the product name of ZLI-4792 manufactured by Merck. A liquid crystal display cell was produced by injecting and sealing the liquid crystal marked with. The vertical alignment of the liquid crystal was tested by observing the prepared cell in a crossed nicols state under a polarizing microscope and observing the isogery state in the microscope field. Further, this vertical alignment property was similarly tested after the cells were heat-treated at 100 ° C. for 10 minutes.

Separately, a polarizing plate was attached to the cell prepared in the same manner as above, and the orientation of the liquid crystal was tested by visually observing the transmitted light state of the cell. This orientation is 1
The same test was performed after heat treatment at 00 ° C. for 10 minutes. The results of these tests are shown in Table 2. In the table, for the vertical alignment, ○ indicates that a clear isogyre is observed, the liquid crystal of the cell exhibits good vertical alignment, and Δ indicates that the center of the isogyre is displaced.
The liquid crystal of the cell shows a slightly weak vertical alignment, and ×
The marks indicate that no isogyre was observed and the liquid crystal of the cell did not exhibit vertical alignment. Also, in the table,
Regarding Orientation, ○ indicates that the liquid crystal of the cell shows uniform orientation, Δ indicates that the liquid crystal of the cell shows slightly disordered orientation, and × indicates that the liquid crystal of the cell does not show orientation. .

[0041]

[Table 2] Table 2 Solution used Thermosetting temperature Vertical orientation Orientation (℃) Before heat treatment After heat treatment Before heat treatment After heat treatment L-1 180 ○ ○ ○ ○ L-1 300 ○ ○ ○ ○ L-1 450 △ △ ○ ○ L-2 180 ○ ○ ○ ○ L-3 180 ○ ○ ○ ○ L-4 180 ○ ○ ○ ○ L-5 180 × × × × L-6 180 ○ △ △ × L-7 180 △ △ × × L-8 180 ○ ○ △ △ The results shown in Table 2 are: Even if the solution of (L-1) of the example is used, when a thermosetting film is formed at a temperature of 450 ° C.,
This shows that the liquid crystal vertical alignment of this film is not sufficient. Further, it is shown that the solutions of the polysiloxanes of (L-5) to (L-8) of the comparative example are not sufficient in vertical alignment and alignment.

[0042]

EFFECTS OF THE INVENTION According to the present invention, a coating solution can be efficiently prepared by only mixing raw materials and performing heat treatment once. Since it is stable for more than 6 months, it can be supplied as an industrial product. This coating solution can be applied to conventionally used electrode substrates. Then, the liquid crystal vertical alignment film can be easily formed on the electrode substrate simply by applying the coating liquid to the electrode substrate, drying it if necessary, and then thermally curing it.

The liquid crystal alignment film of the present invention exhibits excellent liquid crystal vertical alignment and alignment uniformity, and has durability so that its performance does not deteriorate even when heated. Further, if necessary, a so-called rubbing treatment of rubbing with a cloth made of nylon, cotton, rayon, or the like can be applied to the surface of the formed alignment film to form a film with better vertical alignment. .

The liquid crystal alignment film of the present invention is effective for various liquid crystals which have been conventionally used. Then, the coating liquid of the present invention can be used in a conventionally used method for manufacturing a liquid crystal display cell.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takeshi Hosoya 1 722, Tsuboi-cho, Funabashi-shi, Chiba Central Research Laboratory, Nissan Chemical Industries, Ltd.

Claims (3)

[Claims] 1. The following general formula (1) Si (OR) ₄ ... (1) (wherein R has 1 to 5 carbon atoms) Represents an alkyl group) and a silicon compound (A) represented by the following general formula (2) R ¹ Si (OR) ₃ (2) ( Provided that R ¹ represents an alkyl group having 3 to 20 carbon atoms, which is unsubstituted or has a fluorine atom substituent, and R is the same as the above). , The following general formula (3) R ² CH ₂ OH (3) (wherein R ² represents a hydrogen atom or 1 to 12 carbon atoms). Which represents an unsubstituted or substituted alkyl group) and oxalic acid (D) are silicified with respect to 1 mol of the silicon compound (A). Elementary compound (B)
In a ratio of 0.05 to 0.43 mol, in a ratio of 0.5 to 100 mol of alcohol (C) to 1 mol of all alkoxy groups contained in silicon compound (A) and silicon compound (B), and silicon. A reaction mixture containing oxalic acid (D) in an amount of 0.2 to 2 moles based on 1 mole of all alkoxy groups contained in the compound (A) and the silicon compound (B) is formed, and the reaction mixture is formed therein. 0.5 converted from the silicon atom of
While maintaining the SiO ₂ concentration of 10% by weight and the absence of water, the total amount of the silicon compound (A) and the silicon compound (B) in the reaction mixture is 50 to 50 mol% until the total residual amount becomes 5 mol% or less. By heating at 180 ° C., a solution of the resulting polysiloxane is produced, and then a coating solution containing the solution of the polysiloxane is applied to the surface of the electrode substrate, and the coating film obtained by this application is applied to 80 ° C. ~ 4
A method of forming a liquid crystal vertical alignment film in close contact with the surface of the electrode substrate, which comprises heat curing at 00 ° C. 2. The following general formula (1) Si (OR) ₄ ... (1) (wherein R has 1 to 5 carbon atoms) Represents an alkyl group) and a silicon compound (A) represented by the following general formula (2) R ¹ Si (OR) ₃ (2) ( Provided that R ¹ represents an alkyl group having 3 to 20 carbon atoms, which is unsubstituted or has a fluorine atom substituent, and R is the same as the above). , The following general formula (3) R ² CH ₂ OH (3) (wherein R ² represents a hydrogen atom or 1 to 12 carbon atoms). Which represents an unsubstituted or substituted alkyl group) and oxalic acid (D) are silicified with respect to 1 mol of the silicon compound (A). Elementary compound (B)
In a ratio of 0.05 to 0.43 mol, in a ratio of 0.5 to 100 mol of alcohol (C) to 1 mol of all alkoxy groups contained in silicon compound (A) and silicon compound (B), and silicon. A reaction mixture containing oxalic acid (D) in an amount of 0.2 to 2 moles based on 1 mole of all alkoxy groups contained in the compound (A) and the silicon compound (B) is formed, and the reaction mixture is formed therein. 0.5 converted from the silicon atom of
While maintaining the SiO ₂ concentration of 10% by weight and the absence of water, the total amount of the silicon compound (A) and the silicon compound (B) in the reaction mixture is 50 to 50 mol% until the total residual amount becomes 5 mol% or less. A coating liquid containing a solution of polysiloxane obtained by heating at 180 ° C. for forming a liquid crystal vertical alignment film on the surface of an electrode substrate. 3. The following general formula (1) Si (OR) ₄ ... (1) (wherein R has 1 to 5 carbon atoms) Represents an alkyl group) and a silicon compound (A) represented by the following general formula (2) R ¹ Si (OR) ₃ (2) ( Provided that R ¹ represents an alkyl group having 3 to 20 carbon atoms, which is unsubstituted or has a fluorine atom substituent, and R is the same as the above). , The following general formula (3) R ² CH ₂ OH (3) (wherein R ² represents a hydrogen atom or 1 to 12 carbon atoms). Which represents an unsubstituted or substituted alkyl group) and oxalic acid (D) are silicified with respect to 1 mol of the silicon compound (A). Elementary compound (B)
In a ratio of 0.05 to 0.43 mol, in a ratio of 0.5 to 100 mol of alcohol (C) to 1 mol of all alkoxy groups contained in silicon compound (A) and silicon compound (B), and silicon. A reaction mixture containing oxalic acid (D) in an amount of 0.2 to 2 moles based on 1 mole of all alkoxy groups contained in the compound (A) and the silicon compound (B) is formed, and the reaction mixture is formed therein. 0.5 converted from the silicon atom of
While maintaining the SiO ₂ concentration of 10% by weight and the absence of water, the total amount of the silicon compound (A) and the silicon compound (B) in the reaction mixture is 50 to 50 mol% until the total residual amount becomes 5 mol% or less. A method for producing a coating liquid for forming a liquid crystal vertical alignment film on the surface of an electrode substrate, which comprises heating at 180 ° C.