JPH02221923A - Composition for forming transparent electrode protective film of liquid crystal display element and liquid crystal display element - Google Patents

Abstract

PURPOSE:To obtain the coating film which cures at a low temp., has excellent wettability and is free from repellent phenomena by forming the electrode protective film of a compsn. composed of specific terminal hydroxy ladder polysiloxane, specific org. metal compd. and solvent. CONSTITUTION:The transparent electrode protective film is formed by using the compsn. prepd. by dissolving the terminal hydroxy ladder polysiloxane which is expressed by general formula I (where R1 and R2 are hydrogen or monovalent hydrocarbon group; n is a positive integer) and in which >=55% of R1 and/or R2 of the general formula I consists of a phenyl group and the number average mol. wt. is 2,000 to 500,000 and the org. metal compd. expressed by general formula II (where M is a metal element; R' is hydrogen or monovalent hydrocarbon group; m is a positive integer) into the solvent. As a result, the protective film which is cured by a low-temp. heat treatment is formed and the long-life liquid crystal element is obtd. without increasing the sheet resistance value of the electrodes.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a composition for forming a transparent electrode protective film for a liquid crystal display element and a liquid crystal display element, and more particularly to a composition for forming a transparent electrode protective film for a liquid crystal display element, and more particularly to a composition for forming a transparent electrode protective film on a liquid crystal display element, and more particularly to a composition for forming a transparent electrode protective film on a liquid crystal display element. The present invention relates to a composition for forming a transparent electrode protective film and a liquid crystal display element in which a protective film is formed using the composition.

[Conventional technology]

Conventionally, when manufacturing liquid crystal display elements, a method has been used in which an alignment film made of an organic polymer such as polyimide is coated on a substrate having a patterned transparent electrode, and after alignment and alignment processing is performed, the element is assembled. It was getting worse. However, in recent years, as liquid crystal display elements have become larger, foreign matter that has gotten into pinholes in the alignment film or gaps between the elements, and spacers inserted between the substrates to maintain a constant gap can damage the alignment film. Display defects due to conduction between the upper and lower substrates caused by puncturing have become a problem.

Recently, as a means to solve this problem, methods of forming an insulating layer between the transparent electrode and the alignment film have been studied. For example, (1) forming an oxide film at low temperature by sputtering, (2) using alkoxysilane , a method has been adopted in which a solution containing alkoxytitanium and an organic polymer as a thickener is applied by a printing method or the like, and then heat-treated to form an oxide film.

However, method (1) requires expensive vacuum equipment and has the disadvantage of poor productivity due to batch processing, while method (2) requires high-temperature treatment to form an oxide film. There were drawbacks such as an increase in the sheet resistance of the transparent electrode.

[Problem to be solved by the invention]

As a method to solve this problem, the present inventors investigated a composition in which a terminal hydroxyl ladder polysiloxane and an organometallic compound were dissolved in a solvent, but the film formed from this composition had poor wettability. However, it has been found that when a composition for forming a liquid crystal alignment film is applied onto this protective film, repellency occurs.

The object of the present invention is to eliminate the drawbacks of the above-mentioned techniques, to provide a composition for forming a transparent electrode protective film of a liquid crystal display element, which can be cured by low-temperature heat treatment, the cured film has excellent wettability, and does not generate repellency. Another object of the present invention is to provide a liquid crystal display element using the same.

[Means to solve the problem]

As a result of intensive studies in view of the above problems, the present inventors found that a composition in which a specific terminal hydroxyl ladder polysiloxane and a specific organometallic compound are dissolved in a solvent is cured by low-temperature heat treatment, and the cured film is The inventors have discovered that a composition for forming a liquid crystal alignment film can form an excellent protective film for transparent electrodes without causing repellency when applied, and have arrived at the present invention.

That is, the present invention provides (a) - binding allowance (1) (in the formula, R8
and R2 is hydrogen or a monovalent hydrocarbon group, n is a positive integer), and 55% or more of R and/or R2 in the binding margin (1) consists of a phenyl group, a number Terminal hydroxyl ladder polysiloxane having an average molecular weight of 2°000 to 500,000, (b) - binding margin (II)
M(OR')m (II) (wherein M is a metal element, Ro is hydrogen or a monovalent hydrocarbon group, m
means a positive integer) and a composition for forming a transparent electrode protective film of a liquid crystal display element containing the solvent (C), and using the composition for forming a transparent electrode protective film. The present invention relates to a liquid crystal display element having a transparent electrode protective film formed thereon.

The terminal hydroxy ladder polysiloxane represented by the above-mentioned binding margin (1) used in the present invention is selected from the viewpoint of preventing the occurrence of cissing, when R1 and/or R8 in -1G formula (I)
5% or more of phenyl groups, and from the viewpoint of viscosity and curability as a coating liquid, the number average molecular weight is 2,000 to 5.
00,000, preferably 10,000-50,000
is within the range of

The terminal hydroxyl ladder polysiloxane can be obtained by hydrolyzing phenyltrichlorosilane using a large amount of water, as shown in Japanese Patent Publication No. 58-50657, for example.
The resulting hydrolyzate is subjected to dehydration condensation polymerization in toluene using carbodiimides as a catalyst. In this case, R1 and R2 in the above-mentioned binding margin (1) are phenyl groups, but in the present invention, R+ and/or R2 are
In addition to the phenyl group, it may be an alkyl group such as a methyl group or an ethyl group, an aryl group such as a chlorophenyl group, or a hydrogen atom, and one or more of these may be contained in the molecule. Further, the terminal hydroxy ladder polysiloxanes can be used alone or in combination of two or more. The concentration of the terminal hydroxy ladder polysiloxane in the composition varies depending on its molecular weight and coating film thickness, but is preferably 5 to 20% by weight. -n in Tsukuriyo (1)
is usually an integer of 1 to 1000, preferably an integer of 5 to 500.

As the organometallic compound represented by the above-mentioned binding margin (II) used in the present invention, T i (OR' ) a, Z
r (OR”)4 , Ta (OR”)5 , In (
There are compounds such as OR')3 and Si(OR')4,
As R', CHz, Ct Hs, C3Ht,
There are CaI2, Cs H++, etc., CH,, C, HS
, iC3Ht , n Cm Ht, 1-C4H,, n
-C=Hq is preferred. - In the binding allowance (Il), m is
It is usually an integer of 2 to 6, preferably 3 to 5. Specific examples include tetraisopropoxytitanium, tetrabutoxyzirconium, tetraethoxyzirconium, pentaethoxytantalum, tributoxyindium, and tetraethoxysilane. These compounds react with the terminal hydroxyl group of the terminal hydroxyl ladder polysiloxane to form a Si-0-M bond and act as a crosslinking agent at low temperatures. Further, by adding it, the refractive index of the protective film to be formed can be controlled, and phenomena such as so-called Nesa black, in which the transparent electrode pattern is visible when not lit, can be prevented. When these organometallic compounds are used mainly as a crosslinking agent, the concentration of hydroxyl groups in the terminal hydroxyl ladder polysiloxane is 10%.
~100 mol% is preferable, and when the main purpose is to control the refractive index, an organometallic compound such as titanium or zirconium is used, and the ratio of the metal atom to the Si atom is 10 to 1 mol%.
It is preferable to set it to 00 mol%.

Solvents used in the present invention include N,N-dimethylacetamide, N-methyl-2-pyrrolidone butyl cellosolve, hexylene glycol, butyl cellosolve, N-
Examples include methyl-2-pyrrolidone and diethylene glycol.

The composition of the present invention can be obtained by dissolving the terminal hydroxyl ladder polysiloxane in a solvent at room temperature or higher temperature, then adding the organometallic compound and dissolving with stirring.

The composition of the present invention is applied onto a substrate on which a pattern of transparent electrodes is formed, for example, using a printing machine such as a roll coater, a spinner coater, etc. It is heat-treated with a plate or the like and used as a protective coating for the transparent electrode. The heat treatment time is preferably about 30 to 90 minutes in the case of an oven, and about 10 to 30 minutes in the case of a hot plate. Further, the thickness of the protective film to be formed is preferably 500 to 2000 from the viewpoint of dielectric strength.

〔Example〕

Hereinafter, the present invention will be explained in detail with reference to Examples.

Example 1 (A) Synthesis of terminal hydroxy ladder polysiloxane Phenyltrichlorosilane (C6H5S i Cf3)
58.18 g (0,275 mol) and methyltrichlorosilane (CH3S i Cl13') 33.63
g (0°225 mol) in 200 m diethyl ether
Dissolved in l. Meanwhile, put 11 ion-exchanged water into Yotsuro flask 21, attach a stirrer, cooler, and thermometer,
The flask was cooled to 20° C. or lower in a water bath, and the above ether solutions of phenyltrichlorosilane and methyltrichlorosilane were added dropwise through a dropping funnel to effect hydrolysis. The reaction temperature was kept at 20°C or less, and the dropwise addition was completed in 4 hours. Stirring was stopped, and the reaction solution separated into two layers was put into a separating funnel and the ether layer was taken out. The ether layer was washed with ion-exchanged water until it became neutral, and then dried over anhydrous sodium sulfate overnight. Thereafter, the ether was removed, and the mixture was placed in a vacuum dryer and dried at 60°C for 2 hours. The obtained white powder showed an 10H absorption at 350OCT11-1 and a 5t-0-3t absorption at 1130cl' and 1135cm-' in its IR spectrum. Its number average molecular weight was about 1,000.

Next, 10 g of the white powder hydrolyzate was weighed into a Mitsuro flask equipped with a reflux condenser, a stirrer, and a thermometer.
30 ml of toluene was added as a solvent and dissolved to form a uniform layer. 4.1 g of dicyclohexylcarbodiimide as a condensation catalyst was added and dissolved in this, and the mixture was reacted at 110"C under stirring and reflux for 2 hours. After the reaction, precipitation of a carbon derivative was observed in the reaction vessel. The reaction was completed. After that, the reaction mixture was allowed to cool, the urinary direa derivative was suction filtered, and the polymer was precipitated by pouring it into 10 times the volume of methanol, which was then filtered and dried under reduced pressure.The number average molecular weight of the obtained polymer was is 50.00
0, and its rR spectrum includes 3500 cm-
Absorption due to 10H was observed in ', confirming that it was a terminal hydroxyl ladder polysiloxane.

Next, using phenyltrichlorosilane and methyltrichlorosilane alone as starting materials, they were reacted by the above method to synthesize terminal hydroxypolyphenyl ladder polysiloxane and terminal hydroxypolymethyl ladder polysiloxane. When measuring the IR spectra of these polymers, all of them show 5
Absorption of i-0-3i was observed. Furthermore, the terminal hydroxy polymethyl ladder polysiloxane is 1260c+r'
(The absorption based on 5i-CHx is close to 3030cl, and the terminal hydroxypolyphenyl ladder polysiloxane is
Absorption based on the CH stretching vibration of the phenyl group was observed in '.

IR of terminal hydroxy polymethyl ladder polysiloxane
Based on the peak intensity ratio of 1260cm-' of 5i-CHZ to 113Qcm-' of 5i-0-3i in the chart, the terminal synthesized from phenyltrichlorosilane (0,225 mol) and methyltrichlorosilane (0,275 mol) Hydroxy Ladder Polysiloxane 126
Comparing the peak intensity ratio of 0 cm-'/1130 cm-, the value of the peak intensity ratio of terminal hydroxy ladder polysiloxane synthesized from phenyltrichlorosilane (0,225 mol) and methyltrichlorosilane (0,2'75 mol) is It was found to be about 45% of the peak intensity ratio value of the terminal hydroxy polymethyl ladder polysiloxane. Also, since there is a peak at 3030 cm-', this polymer is terminal hydroxypolyphenylmethyl ladder polysiloxane, and the proportion of phenyl groups is 55%.
It will be.

(B) Preparation and evaluation of composition for forming a protective film 5 g of the terminal hydroxypolyphenylmethyl ladder polysiloxane obtained above was weighed into a four-eye flask equipped with a reflux condenser, a stirrer, a thermometer, and a dropping funnel. Then, 60 g of N,N-dimethylacetamide and 30 g of hexylene glycol were added as a solvent, and the mixture was stirred and dissolved. Next, 5 g of a 10% by weight isopropyl alcohol solution of tetraisopropoxytitanium was added dropwise from the dropping funnel with stirring, and the mixture was stirred and mixed at room temperature for about 2 hours to obtain a composition for forming a protective film. The solid content concentration of this composition is 5.1% by weight (200°C/2
hr drying) and the viscosity at 25°C was 40 centipoise.

The obtained composition was applied onto a silicon wafer using a spinner, heat treated at 150°C for 1 hour, and then heated for 3 hours.
Heat treatment was performed at 00°C for 1 hour to form a film with a thickness of 2000 mm. depositing 2 mn of 1M electrodes on the coating;
When the dielectric breakdown voltage was measured, it showed a withstand voltage of about 100V.

Next, the above composition was applied by a printing method onto a 300 x 150 mm glass substrate on which a transparent electrode pattern of 640 x 200 dots was formed, and then heat treatment was performed in the same manner as above, and a thickness of 1
000 people were coated.

An 800-layer polyimide alignment film was formed on the film, a cell was assembled, and the alignment state when voltage was applied was observed. As a result, no defective alignment or Nesa black due to conduction between the upper and lower substrates was observed. In addition, in the cell assembly process, a liquid crystal alignment film composition (manufactured by Hitachi Chemical Co., Ltd., LX-140
No repellency occurred when 0-04) was applied onto a transparent electric scratch protective coating.

Comparative Example 1 A terminal with a number average molecular weight of 20,000 was prepared in the same manner as in Example 1(A) except that only methyltrichlorosilane was used instead of phenyltrichlorosilane and methyltrichlorosilane. Hydroxy polymethyl ladder siloxane was synthesized. In addition, 5 g of this was weighed into the same flask as in Example 1 (B),
As a solvent, 60 g of N-methyl-2-pyrrolidone and 30 g of butyl cellosolve were added and dissolved with stirring, and then 5 g of a 10% butyl cellosolve solution of tetrabutoxyzirconium was added dropwise from the dropping funnel with stirring.
The mixture was stirred and mixed for a period of time to obtain a composition for forming a protective film. The solid content concentration of the obtained composition was 4.9% by weight (2% by weight at 200°C).
The viscosity at 25° C. was 20 centivoise.

When the film properties of this composition were evaluated in the same manner as in Example 1 (B), the dielectric strength voltage was 45 V/1000 people. However, when the alignment film composition was applied, repellency occurred.

Comparative Example 2 In Example 1 (A), a number average molecular weight of ff 120,000 was prepared in the same manner as in Example 1 (A) except that phenyltrichlorosilane and methyltrichlorosilane were used in a molar ratio of 1:1. A terminal hydroxy polyphenylmethyl ladder polysiloxane was synthesized. Further, 5 g of this was weighed into the same flask as in Example 1 (B), and 60 g of N-methyl-2-pyrrolidone and 30 g of butyl cellosolve were added as solvents and dissolved with stirring. Furthermore, 5 g of 10% butyl cellosolve solution of tetrabutoxyzirconium
was added dropwise from the dropping funnel while stirring, and the mixture was stirred and mixed at room temperature for about 2 hours to obtain a composition for forming a protective film. The solid content concentration of the obtained composition was 4.9% by weight (drying at 200°C for 2 hours), and the viscosity at 25°C was 20 centivoise.

When an alignment film was applied on a protective film prepared by applying and curing this composition, repellency occurred in a part of the coating film.

〔Effect of the invention〕

According to the composition for forming a transparent electrode protective film of a liquid crystal display element of the present invention, a transparent electrode protective film can be formed by a simple application method and cured by low-temperature heat treatment, so that the sheet resistance of the transparent electrode can be There is no rise in the temperature, and it is possible to prevent poor alignment and blackness due to conduction between the upper and lower substrates. Furthermore, the protective film formed using this composition for forming a transparent electrode protective film remains unchanged even when an alignment film composition is applied thereon.
Since no scratching occurs, the life and reliability of liquid crystal display elements and liquid crystal display boards produced using the composition can be improved.

Claims (1)

[Claims] 1. (a) General formula (I) ▲ Numerical formulas, chemical formulas, tables, etc. ▼ (I) (In the formula, R_1 and R_2 are hydrogen or a monovalent hydrocarbon group, and n is a positive integer. ), and the general formula (
I) in which 55% or more of R_1 and/or R_2 consists of phenyl groups, and the number average molecular weight is 2,000 to 50
0,000, (b) general formula (II) M(OR')_m(II) (wherein M is a metal element, R' is hydrogen or a monovalent hydrocarbon group, m is 1. A composition for forming a transparent electrode protective film of a liquid crystal display element, comprising an organometallic compound represented by (meaning a positive integer) and (c) a solvent. 2. A liquid crystal display element having a transparent electrode protective film formed using the composition for forming a transparent electrode protective film according to claim 1.