JPS5821246B2 - LCD holding board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION In the present invention, nematic or cholesteric liquid crystal molecules are brought into a homogeneous (horizontal) alignment state in advance, and an electric field and
The present invention relates to a liquid crystal display device that utilizes alignment deformation of liquid crystal molecules caused by changing the intensity of a magnetic field, heat, etc., and is provided with means for improving the quality of initial homogeneous alignment.

Typical liquid crystal display systems include twisted nematic field effect display, flexiblex (induced birefringence field effect) display, dynamic scattering display, and cholesteric nematic transition dichroic display. method,
There are orientation vibration type display methods, etc.

However, it goes without saying that the present invention is effective not only in these display systems but also in all systems that require homogeneous alignment in the initial state (unexcited state).

Conventionally, a method is known in which liquid crystals are aligned using an obliquely vapor-deposited film of silicon oxide or the like.

However, there are differences in alignment ability depending on the type of liquid crystal substance, and it has been experimentally confirmed that there are some liquid crystal substances that cannot be fully aligned using the above-mentioned alignment method.

This poses a major problem when a mixture of various liquid crystals is used to improve the temperature characteristics or electro-optical characteristics of the liquid crystal.

Also known are methods for aligning liquid crystals by applying various surface treatment agents and rubbing treatment to organic polymer coatings.

However, known surface treatment agents and organic polymer coatings have low heat resistance due to the rubbing effect, so most of them have drawbacks such as poor orientation due to heating during device assembly or the influence of sealants. Therefore, the good heat resistance of the rubbing effect was limited to heat-resistant organic polymer coatings such as polyimide.

In addition, since these heat-resistant organic coatings are yellow and colored,
There was a problem with display quality.

In particular, for color display such as a cholesteric nematic transition type two-color display system, it is desirable that the alignment film be uncolored.

The present invention eliminates the above-mentioned drawbacks of the prior art, and makes it possible to orient the molecular axis of liquid crystal parallel to the substrate surface and in the characteristic direction of the substrate surface, regardless of the type of liquid crystal substance, and to improve the heat resistance of this liquid crystal alignment regulation. The object of the present invention is to provide a liquid crystal display device which is stable over time, has a long life, has high characteristics, is colorless, and has high display quality by not placing any restrictions on liquid crystal element assembly.

The present invention has been made in this regard, and by forming a film made of a ladder-type organosilicone polymer having a phenyl group or a nuclear-substituted phenyl group continuously on the substrate surface in contact with the liquid crystal, there is no coloring of the element. It is characterized by obtaining extremely high quality homogeneous orientation even after device assembly.

Ladder-type organosilicone polymers having phenyl groups or nuclear-substituted phenyl groups include polyphenylalkylsilsesquioxanes with the following structure, and are estimated to have a ladder structure based on X-ray diffraction, infrared absorption spectra, etc. .

However, R is a phenyl group or a nuclear-substituted phenyl group such as a halogenated phenyl group or a halogenated methylphenyl group, and even if a part of R is an alkyl group such as methyl, ethyl, propyl, butyl, or amylhexyl. good.

The glass substrate used is not particularly limited, although a layer such as spin-on glass formed on the side in contact with the liquid crystal to act as a barrier for Na + ions is better in terms of heat resistance for liquid crystal orientation.

The present invention will be explained below with reference to Examples.

Example 1 Polyphenylsilsesquioxane is dissolved in a solvent such as benzene, and this solution is applied using a spinner or the like to a glass substrate selectively coated with a transparent electrode such as indium oxide.

This is generally heated between 200°C and 300°C for 0.5 to 2 hours.

This coating film was uncolored, and by rubbing it, it was possible to obtain extremely good homogeneous alignment for various liquid crystals.

This rubbing effect does not deteriorate even after heat treatment at 450° C. for 1 hour, and element assembly using glass frit is possible.

Also, when the device was assembled using an epoxy adhesive that cured at 200° C. for 1 hour, no deterioration in alignment occurred.

Example 2 Polyphenylisobutylsilsesquioxane (C6H5
: 1C4H9=3:1) was dissolved in a solvent such as cyclohexane, a coating film was prepared in the same manner as in Example 1 using this solution, and this was subjected to a rubbing treatment.

This coating film was also uncolored and was able to obtain extremely good quality homogeneous alignment for various liquid crystals.

This rubbing effect does not deteriorate even after heat treatment at 450° C. for 1 hour, and element assembly using glass frit is possible.

Also, when the device was assembled using an epoxy adhesive that cured at 200° C. for 1 hour, no deterioration in alignment occurred.

Example 3 Poly(m-chlorophenyl)silsesquioxane (one of the nuclear-substituted phenyl groups) was dissolved in a solvent such as benzene, and this solution was used to create a coating film in the same manner as in Example 1. was subjected to rubbing treatment.

This coating film was also uncolored and was able to obtain homogeneous alignment for various liquid crystals.

This rubbing effect does not deteriorate even after heat treatment at 450° C. for 1 hour, and element assembly using glass frit is possible.

Also, when the device was assembled using an epoxy adhesive that cured at 200° C. for 1 hour, no deterioration in alignment occurred.

Comparative Example 1 Linear polymer type polyphenylmethylsiloxane (C6
Using a toluene solution of H5:CH3=7.3=1),
A coating film was prepared in the same manner as in Example 1 and textured by rubbing.

Due to this coating film, the number of liquid crystals that are homogeneously aligned is limited, and most liquid crystals are vertically aligned.

Also, in the case of homogeneously aligned liquid crystals, the heat resistance of this rubbing effect is low and cannot be put to practical use.

Comparative Example 2 An ethanol solution of phenyltriethoxysilane was applied to a glass substrate selectively coated with a transparent electrode such as indium oxide, heated at 200° C. for 1 hour, and then rubbed.

This coating film homogeneously aligns various liquid crystals, but the heat resistance and adhesive stain resistance of this rubbing effect are low.
The rubbing effect was completely lost even after heat treatment at 0° C. for 1 hour and when assembling the device using epoxy adhesive K1 that cured at 200° C. for 1 hour.

Comparative Example 3 An N-methylpyrrolidone solution of polyimide manufactured by DuPont is applied to a glass substrate selectively coated with a transparent electrode such as indium oxide using a spinner or the like.

This was heated at 250° C. for 1 hour to cure the film, and the film was rubbed.

Although this coating film aligns various liquid crystals well, the coating film is yellow and colored, and there is a problem in display quality.

Furthermore, this rubbing effect does not pose a problem when the device is assembled using epoxy resin that is cured at 200°C for 1 hour, but
Heat treatment at 50° C. for 1 hour induces domains (orientation defects) at the electrode edges during operation.

(For the above example words, the responsiveness of the liquid crystal alignment element to various liquid crystals is shown in the table.

The rubbing film of linear polymer-type silicone resin has a strong tendency to homeotropically (vertically) align liquid crystal molecules, whereas the ladder-type organosilicone polymer rubbing film with phenyl groups according to the present invention can homogeneize various liquid crystals extremely well. Orient.

Furthermore, while the heat resistance of the rubbing effect of the surface treatment film using phenyltriethoxysilane is low, the ladder-type organosilicone polymer rubbing film with phenyl groups according to the present invention has excellent heat resistance of the rubbing effect and adhesive stain resistance. The coating film is also colorless and has high display quality.

Here, various types of liquid crystals include Schiff-based liquid crystals, biphenyl-based liquid crystals, azooxy-based liquid crystals, azo-based liquid crystals, ester-based liquid crystals, phenylcyclohexane-based liquid crystals, phenylpyrimidine-based liquid crystals, cholesterol derivative liquid crystals, mixtures thereof, or non-liquid crystals. Contains liquid crystals containing optically active substances and mixed liquid crystals.

Note that the glass substrates used in the above Examples and Comparative Examples have a spin-on glass layer formed on the side in contact with the liquid crystal.

It goes without saying that the homogeneous alignment produced by the uncolored alignment film of the present invention improves the characteristics of the display device, such as uniform display, constant viewing angle direction, constant electro-optic effect threshold, and improved response characteristics. However, since the alignment film is not colored,
In particular, display quality can be improved in color display and the like.

[Brief explanation of the drawing]

The figure is a cross-sectional view of a liquid crystal display cell. DESCRIPTION OF SYMBOLS 1... Glass substrate, 2... Transparent conductive film, 3... Alignment control film, 4... Liquid crystal, 5
... Sealing agent, 6 ... Polarizing plate.

Claims (1)

[Claims] 1. In a liquid crystal holding substrate that sandwiches a liquid crystal to constitute a liquid crystal display device, an electrode formed on the surface of the liquid crystal holding substrate in contact with the liquid crystal, and a phenyl group or A liquid crystal sandwiching substrate comprising a ladder-type organosilicone polymer film having a nuclear-substituted phenyl group. 2. The liquid crystal holding substrate according to claim 1, wherein the ladder-type organosilicone polymer film having a phenyl group or a nuclear-substituted phenyl group is polyphenylalkylsilsesquioxane.