JPS60258517A - Liquid crystal display element - Google Patents

Abstract

PURPOSE:To obtain an excellent oriented film which has good adhesivensss, is resistant to heat in a rubbing treatment and does not crack even at a high temp. by using a coating liquid consisting particularly of ladder type polysiloxane, silanol compd. and org. solvent, etc. to form the oriented film on a transparent substrate. CONSTITUTION:The soln. prepd. by dissolving the ladder type polysiloxane having an org. group of the terminal cage type expressed by the formula together with the silanol compd. which is the hydrolyzate of the compd. expressed by the formula RSiX3 (R is an alkyl group of 1-18C, aryl-, alkenyl-, alkyl group contg. an epoxy group, etc., X is alkoxy group of 1-4C, halogen) and/or the formula Si(OR)4 (R is alkyl group of 1-4C) and if necessary, a curing catalyst in an org. solvent is coated on a substrate and is cured by heating. The surface thereof is rubbed and polished in a specified direction by which the oriented film is formed. Such oriented film is colorless and transparent, is highly resistant to the heat in the rubbing treatment, has good adhesiveness to the substrate, is low in the heating temp. for curing the coated film and does not crack at a high temp. Such oriented film is effective for all nematic liquid crystals and the mixture composed thereof and is used for a TV, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a liquid crystal display element, and more particularly to a liquid crystal alignment film. Generally, the liquid crystal often used in liquid crystal display elements is nematic liquid crystal.

Nematic liquid crystal has the property that its molecular axes are aligned in the same direction, and the alignment direction is parallel or perpendicular to the substrate surface. The alignment parallel to the substrate surface is called homogeneous alignment, and the alignment perpendicular to the substrate surface is called homeotropic alignment.

The present invention will be explained using homogeneous orientation as an example. Liquid crystal display is possible because liquid crystal molecules are already in a uniformly aligned state, and by changing the intensity of external electric fields, magnetic fields, heat, etc., the alignment state of liquid crystal molecules can be changed. be. Although there are various display methods such as a field effect type, the present invention is effective not only in these methods but also in all methods that require homogeneous orientation in the initial state.

Conventionally, the following methods have been used to cause liquid crystal molecules to assume homogeneous alignment in an initial state.

(Method of diagonally evaporating 11S i O, (2) Lap/Gluing method (12) Friction polishing the electrode substrate itself.

(b) A coating film is formed on the electrode substrate using a surface treatment agent, and the coating film is friction-polished.

(C) A coating film is formed on the electrode substrate using a cyrano coupling agent, and the coating film is friction-polished.

(d) A polyimide coating is formed on the electrode substrate, and the coating is friction-polished.

(e) A coating film is formed on the electrode substrate using an end-cage type polyladder type organosiloxane, and the coating film is friction-polished.

(a) A coating film is formed on the electrode substrate using terminal OH type polyladder type organosiloxane, and the coating film is friction-polished.

However, in the method (1) of obliquely vapor depositing 5i02, there may be differences in the ability to align the liquid crystal depending on the type of liquid crystal, or there may be no alignment at all. This is a problem when using a mixture of various liquid crystals to improve their various characteristics (temperature, etc.).

(2) (d), (b), and (C) have the disadvantage that the rubbing effect (liquid crystal orientation) becomes ineffective due to high temperature treatment during sealing around the substrate.

(21(d) has good heat resistance against the rubbing effect (orientation), but requires a high curing temperature of 400 to 450°C, and the substrate is limited to materials that can withstand high temperatures (glass etc.), making it generally The transparent organic polymer has the disadvantage that it cannot be used as a substrate.It also has the disadvantage that the coating film is colored yellowish brown, degrading the display quality.

(21(g) is JP-A No. 55-9527 and JP-A-Sho. 5
5-62427, which has good heat resistance against rubbing effect (orientation), but has poor adhesion to substrates (glass, etc.) and is difficult to clean the coating film during the assembly process of liquid crystal display elements. There are problems such as the coating sometimes peeling off.

(2) (A) is the method presented in JP-A-56-146120 and JP-A-57-56820;
+ Adhesion is improved compared to (g), but the coating film requires high temperatures of 250 to 400°C to cure, and the substrate is limited to materials that can withstand high temperatures (glass, etc.). has the disadvantage that it cannot be used as a substrate. Another drawback is that cracking occurs when this coating is exposed to high temperatures.

Therefore, the purpose of the present invention is to eliminate the above-mentioned drawbacks, to be colorless and transparent, to have heat resistance to rubbing treatment (orientation), to have adhesion to the substrate, to have a low heating temperature for curing the coating film, and to be able to withstand high temperatures. The object of the present invention is to provide an alignment film that does not cause cranking and is effective for all nematic liquid crystals and mixtures of liquid crystals.

As a result of intensive studies aimed at providing the above-mentioned alignment film, the present inventors have discovered that a heat-cured coating film obtained from a composition of a ladder-type polysiloxane having a cage-shaped organic group and a silanol compound is subjected to a rubbing treatment. The inventors have discovered that an alignment film that satisfies the above requirements can be achieved by completing the present invention.

The present invention will be explained in detail below.

In the present invention, a ladder-type polyester having a terminal cage-type organic group represented by the general formula (where t-1J? is an organic group selected from alkyl, aryl, substituted alkyl, and substituted aryl, and the outside represents an integer) is used. The siloxane can be combined with the general formula R81X3 (R is a 01-C24 alkyl group, an aryl group, an alkenyl group, an alkyl group including an epoxy group, an aminoalkyl group, XUC, a ~C4 alkoxy group, or a halogen) and/or a general formula 5i ( OR)
A solution obtained by dissolving a silanol compound, which is a hydrolyzate of a compound of 4 (R is an alkyl group of 01 to C4), and, if necessary, a curing catalyst, in an organic solvent is applied to the substrate,
After heating and curing, the surface is rubbed and polished in a certain direction to form an alignment film.

Ladder type polysiloxanes having an organic group used in the present invention include phenyl ladder type polysiloxanes, tolyl ladder type polysiloxanes, black-mouthed phenyl ladder type polysiloxanes, bromophenyl ladder type polysiloxanes, and methyl/tolyl ladder type polysiloxanes.
Phenyl ladder type polysiloxane, isodutyl phenyl ladder type polysiloxane, isoamyl phenyl ladder type polysiloxane/, normal hexyl phenyl ladder type polysiloxane, methyl ladder type polysiloxane,
These include normal butyl ladder type polysiloxane, naphthyl ladder type polysiloxane, and diphenyl ladder type polysiloxane. Of these, phenyl ladder type polysiloxanes are preferred. These s9
The weight average molecular weight of remer is 1×1 in terms of polystyrene.
03~lXl0'. If the average molecular weight is less than 1XIO3, there will be no film-forming properties, and if it is more than 1x106, it will be difficult to dissolve in solvents.

The silanol compound that can be used in the present invention has the general formula RS Z
4 alkoxy group, halogen) and/or general formula 5i (
OR) and IR are hydrolysates of C7-C4 alkyl groups), and have a molecular weight that is soluble in solvents. Moreover, when using them as a mixture, the mixing ratio is arbitrary. These hydrolysates contain silane compounds [R51X, and/or
or Si(OR)4] in an organic solvent in the presence of an acid or a base.

The mixing ratio of the ladder type polysiloxane having an organic group and the silanol compound can be arbitrarily selected. If the proportion of silanol compounds is small, the heat resistance of the rubbing effect (orientation) of the coating film will be improved due to the properties of ladder-type polysiloxane having organic groups, but the adhesion between the coating film and the substrate will be poor, resulting in poor liquid crystal display Inconveniences such as peeling of the coating film occur during the element assembly process (cleaning of the coating film). Conversely, if the proportion of the silanol compound is high, the adhesion between the coating film and the substrate will improve depending on the properties of the silanol compound, but the heat resistance of the rubbing effect (orientation) of the coating film will deteriorate. Therefore, the mixing ratio can be determined by considering the balance between adhesion, rubbing effect (orientation), and heat resistance, and the mixing ratio of ladder-type polysiloxane having an organic group to silanol compound is usually 9:1. ~1:9, preferably 8:2 to 3:7.

In the present invention, a curing catalyst may or may not be used when forming the alignment film. When a catalyst is used, the curing conditions are low temperature (1
50℃ or less), and if not used, high temperature (15℃ or less) is sufficient.
0 to 400°C) is required. An example of an effective catalyst for low-temperature curing is U, l, 8-diazabicyclo[5゜4,O]-7-undece/, l,4-diazabicyclo[2,2,2') octane. , triethylamine, ethylenediamine, triethanolamine, butylamine, dibutylamine, hexylamine, and other amines; iron, lead, tin, antimony, cadmium, titanium, calcium, bismuth, zirconium, sodium, potassium, cesium, magnesium, and other organic metals Caldate; metal hydroxides such as lithium, sodium, potassium;
benzyltrimethylammonium hydroxide,
4 such as tetramethylammonium hydroxide
M ammonium salts; metal-containing compounds such as diptyltin diacetate, diptyltin dioctate, diptyltin dilaurate, and diptyltin malate; and acidic compounds such as p-toluenesulfonic acid, trichloroacetic acid, and phosphoric acid. The amount used is 0 based on the total weight of the ladder type polysiloxane having an organic group and the silanol compound.
．． 001 to 10 weight ratio is sufficient; if it is less than this, the curing temperature must be as high as 150 to 400°C.
When the amount is more than this, the coating film becomes too hard, causing problems such as cranking. Furthermore, when using a basic curing catalyst, it is effective to add acetic acid as a curing inhibitor, and the amount thereof is preferably 1 to 100 parts by weight, particularly preferably 5 to 50 parts by weight, per 1 part by weight of the catalyst. good.

The coating solution solvent that can be used in the present invention may be any solvent that can dissolve the ladder-type polysiloxane having an organic group and the silanol compound, such as alcohol-based, ester-based, ketone-based, ether-based, aromatic-based, Halodanated hydrocarbon-based solvents, non-aqueous polar solvents, etc. are preferable. For example, ethanol, ethyl acetate, methyl ethyl ketone, inglovir ether, tetrahydrofuran, benzene, anisole,
Examples include fluor, chlorobenzene, and N-methylpyrrolidone. Dissolve the polymer in the above solvent and
．． 01 to 30, and using this as a coating liquid, it is applied to a substrate by a brush coating method, a spin coating method, a spray method, a printing method, a dipping method, or the like.

The coating film curing temperature in the present invention is 50 to 400°C,
When using a curing catalyst, a low temperature of 50 to 150°C is sufficient;
When no catalyst is used, a high temperature of 150 to 400°C is required.

Thickness of alignment film obtained by the present invention [0,01-10
μm is usually good, particularly preferably 0.1 to 3 μm.

Further, its surface is friction-polished in a certain direction with cotton cloth or the like.

Liquid crystals that can be used in the present invention include azoxy type compounds,
Thick base type liquid crystals, such as general formula azo type liquid crystals, such as general formula compounds, taphenyl type liquid crystals, such as general formula chlorohexane type liquid crystals, such as general formula compounds, etc., cholesterol type liquid crystals, and mixtures thereof. In addition, 0.0
1 to 5% by weight of a cholesterol compound, an optically active substance, etc. may be added.

Examples of the substrate used in the present invention include soda glass, quartz glass, Sin, coated soda glass, and colorless transparent organic polymer films (for example, pET films). In particular, since the alignment film of the present invention can be cured at low temperatures, a high-quality alignment film can be produced even on a colorless and transparent organic polymer film, which was impossible with conventional polyimide.

The transparent electrode used in the present invention is obtained by depositing a transparent conductive film containing tin oxide, indium oxide, etc. as a product on the above-mentioned substrate by vacuum evaporation.

The liquid crystal containment sealant used in the present invention may be either an organic sealant or an inorganic sealant.

When the substrate is a colorless transparent organic polymer film, a low temperature curing organic sealant (epoxy type) is used from the viewpoint of heat resistance.

Thus, according to the present invention, it is colorless and transparent, has good heat resistance to rubbing treatment (orientation), does not generate cracks at high temperatures, has good adhesion to the substrate, has a low curing temperature, and is completely resistant to heat. A liquid crystal display element having an alignment film effective for liquid crystals and liquid crystal mixtures is provided.

The liquid crystal display element of the present invention can be used as a display element for various devices by combining reliable alignment with a polarizer or a reflective plate. Examples include display elements such as liquid crystal televisions, electronic computers, wristwatches that require water resistance, thin plastic liquid crystal televisions, thin plastic electronic computers, thin plastic watches, and thin plastic displays.

Next, the present invention will be specifically explained using Examples and Comparative Examples. All parts and units in each example are based on weight.

Example 1 In the accompanying drawings, a transparent electrode 2.1' is shown inside a substrate 1.1'.
2' was selectively vacuum deposited. Next, a ladder type siloxane having a phenyl group and Mg are placed on the substrate and the transparent electrode.
A coating film having a weight ratio of 1:1 with 5i(OEt)s hydrolyzate was formed as follows. That is, a ladder type polysiloxane having a phenyl group having a weight average molecular weight of lXl0' and MeSi(OEt) having a weight average molecular weight of 2xlo''.
A mixture with a hydrolyzate of 3 and a composition of 1:1 by weight was mixed with N-
Dissolved in a mixed solvent of methylpyrrolidone, tetrahydrofuran and monochlorobenzene (weight ratio 3:2:5),
A solution having a polymer concentration of 15% was prepared, and 2 g of 1.8-diazabicyclo-[5゜4.0l-7-undecene was added to the polymer as a curing catalyst, and acetic acid was added as a curing inhibitor to the polymer in an amount of 8% as a curing catalyst. A double amount was added to prepare a coating solution.

This coating solution was coated on the substrate and transparent electrode, and heated at 150°C for 2 hours.
The mixture was heated for a period of time to form a cured coating film. This film was rubbed to form an alignment film 3.3', a sealing layer 5 was made around the substrate with a glass frit adhesive with the alignment film side facing inside, and then a thick liquid crystal mixture 4 was injected. Afterwards, the injection port was finally sealed. Next, the substrate 1. A liquid crystal display element was fabricated by attaching polarizing plates 6 and 6' to the outside of 1' so that the polarization axes were arranged at 90 degrees.

As a result, the liquid crystal showed good alignment. Other results were also good as shown in Table 1.

Examples 2 to 7 Alignment films with other compositions were made under the same conditions as in Example 1 as shown in Table 1. As shown in Table 1, the results showed good orientation and other properties.

Comparative Examples 1 to 3 As the alignment film, polyimide, terminal cage type phenyl ladder type polysiloxane (Jfw=5X10'') or terminal OB
type phenyl ladder type polysiloxane (Mw=7X
10"), and was treated in the same manner as in Example 1. As shown in Table 1, there were problems with the color and physical properties of the alignment film.

[Brief explanation of drawings]

The accompanying drawing is a cross-sectional view of a liquid crystal display element. In the figure, 2 and 1' are substrates, 2 and 2' are transparent electrodes, 3 and 3' are alignment films, 4 is a liquid crystal, 5 is a sealing layer, and 6 and 6' are polarizing plates. Procedural amendment July 17, 1980 Manabu Shiga, Commissioner of the Patent Office1, Indication of the case, Patent Application No. 114385, filed in 1982,2, Name of the invention, liquid crystal display element3, Relationship to the case responsible for the amendment, Patent application Address: 3-35-58 Sakashita, Itabashi-ku, Tokyo, 4th Director, 107 (1) The scope of the specification and claims will be corrected as stated in the attached sheet. (2) Replace “C24” on page 10, line 6 of the specification with F C
+g j and "Correct 1. (3) Change "C2o" on the last line of page 11 of the specification to F C+A
Correct it to Jl. (4) In the formula on page 16, line 12 of the specification, [-N-0] τ, "-N=↓ O" is stopped. Attached Patent Claims ``1. A terminal cage-shaped organic group represented by the general formula % (where R is an organic group selected from alkyl, aryl, substituted alkyl, and tetra-substituted aryl, and n represents an integer) A coating film consisting of a ladder-type polysiloxane, a silanol compound, an organic solvent, and, if necessary, a curing catalyst, is applied onto a transparent substrate, the resulting coating film is heat-treated, and then rubbed and polished in a certain direction to achieve orientation. A liquid crystal display element characterized in that it is a film.2 The silanol compound is R51Xs (R is C1 to
A patent characterized in that it is a hydrolyzate of a CI8 alkyl group, aryl group, alkenyl group, alkynyl group, alkyl group or aminoalkyl group including an epoxy group, where X represents an alkoxy group of 01 to C4 or a halogen) A liquid crystal display element according to claim 1. 3. The silanol compound is 5i(OR)4 (R is CI~
2. The liquid crystal display element according to claim 1, wherein the liquid crystal display element is a hydrolyzate of C4 alkyl group.

Claims (1)

[Scope of Claims] 1. A ladder having a terminal cage-shaped organic group represented by the general formula (where R represents an organic group selected from alkyl, aryl, substituted alkyl, and substituted aryl, and represents an ntri integer) A coating solution consisting of type polysiloxane, a silanol compound, an organic solvent, and if necessary a curing catalyst is applied onto a transparent substrate, and the resulting coating film is heat-treated and then rubbed and polished in a certain direction to form an alignment film. A liquid crystal display element characterized by: 2 The silanol compound is R51X, (R is CI to C
A patent characterized in that the product is a hydrolyzate of 24 alkyl groups, aryl groups, alkenyl groups, alkynyl groups, alkyl groups including epoxy groups, or aminoalkyl groups (X represents a C8 to C4 alkoxy group or halogen) A liquid crystal display element according to claim 1. 3. The liquid crystal display element according to claim 1, wherein the silanol compound is a hydrolyzate of 5i(OR), (R represents a C. to C4 alkyl group). The liquid crystal display element according to item 1.