JPS5826004B2 - LCD holding board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a means for improving the quality of initial homogeneous alignment, which can be used in liquid crystal display devices that require liquid crystal molecules to be homogeneously aligned in an initial state (unexcited state). The present invention relates to a liquid crystal holding substrate.

Conventionally, methods for improving the homogeneous alignment of liquid crystal molecules in the initial state include forming an obliquely evaporated film of silicon oxide or the like on a substrate, or forming a film of various surface treatment agents, organic polymers, etc. , a method of rubbing the film is known.

However, each of these known methods has drawbacks as described below.

That is, the orientation ability of an obliquely deposited film such as silicon oxide differs depending on the type of liquid crystal substance, and there are liquid crystal substances that do not align at all.

This is a very serious problem when using a mixture of various liquid crystals to improve the temperature characteristics or electro-optical characteristics of the liquid crystal.

In addition, in the method of forming a film of various surface treatment agents, organic polymers, etc. and then rubbing the film, the heat resistance of the film is low, so the film deteriorates due to heating during device assembly and the orientation deteriorates. Most of them have the following drawbacks, and only heat-resistant organic polymer films such as polyimide have good heat resistance for orientation regulation.

However, even in these heat-resistant polyimide polymers, if glass frit sealing is performed at 400'C to 450C after rubbing, alignment defects tend to occur when liquid crystal is encapsulated.

In particular, induced domains occur, making it difficult to obtain a liquid crystal display device with stable display characteristics.

This is because in conventional thermogravimetric analysis of polyimide polymers, weight loss is observed to begin at around 400°C, so heating causes changes in the surface state of the polymer film, impairing the rubbing effect, and changing the orientation state of the liquid crystal. It is thought that it can be changed.

JP-A-53-24 has been developed as a polymer film with stable orientation without any change in the film after heat treatment at 400°C or higher as described above.
A polyimide film having an isoindoroquinazolinedione ring is known as described in Japanese Patent Application No. 850, but this film has poor adhesion to the substrate surface, so the coating film is partially coated during the rubbing process. There was a drawback that peeling occurred, resulting in poor orientation such as the formation of domains.

The present inventors conducted studies to eliminate the above-mentioned drawbacks of the prior art, and as a result, they arrived at the present invention.

In other words, the present invention allows the molecular axis of the liquid crystal to be aligned parallel to the substrate surface and in the characteristic direction of the substrate surface, regardless of the liquid crystal substance, and this liquid crystal alignment regulating force has excellent heat resistance and A liquid crystal holding substrate with improved rubbing properties is provided, thereby providing a liquid crystal display device that is stable over time, has a long life, and has high performance without imposing restrictions on the assembly of liquid crystal display elements.

The present invention provides an electrode on the side facing the liquid crystal on a liquid crystal holding substrate, and on the substrate and the electrode, carboxylic acid anhydride, diamine, diamino monoamide, and diamino siloxane are added to the total amount of diamine, diamino monoamide, and diamino siloxane. 0.1 to 50 mol φ of diaminomonoamide
, a polyamic acid containing a siloxane bond obtained by reacting diaminosiloxane at 0.1 to 50 mol φ,
The present invention relates to a liquid crystal holding substrate formed by forming a film of polyimide (hereinafter referred to as polyimide) having a siloxane bond obtained by dehydration ring closure and an isoindoroquinazolinedione ring.

The polyamic acid containing a siloxane bond, which is a precursor of the polyimide used in the present invention, is a carboxylic acid anhydride, a diamine,
It is synthesized by the reaction of diaminomonoamide and diaminosiloxane.

These reactions are carried out under anhydrous conditions, preferably at temperatures of 50°C or less.

Regarding the reaction ratio of carboxylic anhydride, diamine, diaminomonoamide, and diaminosiloxane, it is preferable that the number of moles of carboxylic anhydride and the number of moles of diamine, diaminomonoamide, and diaminosiloxane be equimolar.

This reaction is carried out in the presence of a solvent such as dimethylformamide, dimethylacetamide, dimethylsulfoxide or N-methylpyrrolidone.

Examples of the carboxylic anhydride include pyromellitic anhydride, 2,3,6.7-naphthalenetetracarboxylic anhydride, 3.3',4.4'-diphenyltetracarboxylic anhydride, 1,2, 5,6-naphthalenetetracarboxylic anhydride, 2.2',3゜3'-diphenyltetracarboxylic anhydride, thiophene-2,3,4,5-tetracarboxylic anhydride, 2,2-bis( 3,4-biscarboxyphenyl)propane anhydride, 3,4-dicarboxyphenylsulfone anhydride, perylene-3,4,9,10 tetracarboxylic anhydride, bis(3,4-dicarboxyphenyl)ether anhydride 3.3', 4°4'-benzophenone tetracarboxylic acid anhydride and the like are used.

Examples of the diamine include m-phenylenediamine,
p-phenylenediamine, m-xylenediamine, p-
Xylene diamine, 4.4'-diaminodiphenyl ether, 4.4'-diaminodiphenylmethane, 3.3'
-dimethyl-4,4'-diaminodiphenylmethane, 3
, 3', 5,5'-tetramethyl-4,4'-diaminodiphenylmethane, 2°2'-bis(4-aminophenyl)propane, 4°4'-methylene dianiline, benzine, 4,4'- Diaminodiphenyl sulfide, 4.4
'-diaminodiphenylsulfone, 1,5-diaminonaphthalene, 3,3'-dimethylbenzine, 3,3'-dimethoxybenzine, diaminomonoamide, for example, 1,4-diaminobenzene-2-carbonamide,
4.4'-diaminodiphenyl ether-3-carbonamide and the like are used.

The diaminosiloxane used in the present invention has the general formula (where R is a divalent hydrocarbon group, R1, R2, R3 and R4 are monovalent hydrocarbon groups, and n is an integer of 1 or more).

) are used, examples of which include the following compounds.

For the carboxylic acid anhydride, diamine, diaminomonoamide, and diaminosiloxane, aromatic compounds are preferably used in terms of heat resistance.

Two or more of the carboxylic acid anhydrides, diamines, diaminomonoamides, and diaminosiloxanes may be used in combination.

The ratio of diaminomonoamide and diaminosiloxane contained in diamine, diaminomonoamide and diaminosiloxane is from 0.1 to the total amount of diamine, diaminomonoamide and diaminosiloxane from the viewpoint of adhesion, heat resistance and stability. 50 moles or more, and diaminosilo*xane is said to be 0.1 to 50 moles φ.

The above-mentioned polyamic acid is applied onto the substrate and electrodes by dipping the polyamic acid into a 0.01 to 40 weight φ solution of dimethylformamide, dimethylacetamide, dimethyl sulfoxide, N-methylpyrrolidone, etc. It is applied by a spinner method, a spray method, a printing method, a brush coating method, etc.

100'C~400℃ after coating, preferably 250℃
The above polyamic acid is dehydrated and ring-closed by heat treatment at 0°C to obtain a polyimide film.

Polyimide has a siloxane bond and an isoindoroquinazolinedione ring, and this polyimide contains the following structural units (1), (2), and (3).

In structural units (1) to (3), Ar is, for example, an aromatic residue, Y is S02 or CO, R is a divalent hydrocarbon group, R
' is a monovalent hydrocarbon group, R1 is a tetravalent group, R2 is a divalent hydrocarbon group, and m is an integer of 1 or more.

Hereinafter, the present invention will be specifically explained with reference to Examples and Comparative Examples.

Example I 0.1 mol of 1,3-bis(aminopropyl)-tetramethyldisiloxane and 4,4' in N-methylpyrrolidone
-diaminodiphenyl ether 0.8 mol, 4,4'
-diaminodiphenyl ether-3-carbonamide o
, i mole and 0.1 mole of 3.3', 4.4'-benzophenonetetracarboxylic acid anhydride are condensed to form a siloxane bond and a siloxane bond which is a precursor of a polyimide having an isoindoquinazolinedione ring. A 10% by weight N-methylpyrrolidone solution of polyamic acid having the following formula was applied using a spinner onto a glass substrate on which indium oxide electrodes were formed.

After coating, ring closure was performed by heating at 300° C. for 2 hours to form a polyimide film having a siloxane bond and an isoindoroquinazolinedione ring to a thickness of 80 OA.

Thereafter, the squeeze coating was rubbed in a certain direction with gauze, but no peeling occurred in the coating.

In addition, using a pair of substrates having the above-mentioned rubbed coating, a liquid crystal display cell was prepared by heat-pressing at 450°C for 30 minutes using a low-melting glass frit, liquid crystal was sealed, and the orientation was observed. The orientation was good.

Comparative Example I 0.9 mol of 4,4'-diaminodiphenyl ether, 0.1 mol of 4,4'-diaminodiphenyl ether-3-carbonamide and 3.3 mol in N-methylpyrrolidone
Using a 10% by weight N-methylpyrrolidone solution of polyamic acid, which is a precursor of polyimide having an isoindoquinazolinedione ring obtained by condensing 1.0 mol of ',4,4'-benzophenonetetracarboxylic acid anhydride, A polyimide film having an isoindoroquinazolinedione ring was formed to a thickness of 800 mm by processing in the same manner as in Example 1 above.

Thereafter, when a rubbing process was performed in exactly the same manner as in Example 1, partial peeling occurred from the substrate.

Further, when a liquid crystal display cell was produced in the same manner as in Example 1, poor alignment was observed in some parts.

As shown in the Examples and Comparative Examples, the polyimide film having a siloxane bond and an isoindoroquinazolinedione ring in the present invention exhibits excellent adhesion to the substrate and can withstand all kinds of rubbing treatment conditions.

In addition, the heat resistance of the liquid crystal alignment regulating force is extremely excellent at 450°C or higher, so if the liquid crystal sandwiching substrate of the present invention is used, there will be no restrictions on liquid crystal element assembly such as frit seals, and it will be stable over time and have a long life. A liquid crystal display device with high characteristics can be obtained.

Claims (1)

[Claims] 1 An electrode is provided on the side facing the liquid crystal on the liquid crystal sandwiching substrate, and carboxylic acid anhydride, diamine, diaminomonoamide, and diaminosiloxane are placed on the substrate and the electrode.
A polyamic acid containing a siloxane bond obtained by reacting diaminomonoamide in an amount of 0.1 to 50 moles and diaminosiloxane in an amount of 0.1 to 50 moles φ with respect to the total amount of diaminomonoamide and diaminosiloxane is dehydrated and ring-closed. A liquid crystal sandwiching substrate formed by forming a polyimide film having the obtained siloxane bond and an indoroquinazolinedione ring.