JPS5872923A - Liquid crystal display element - Google Patents

Abstract

PURPOSE:To obtain an oriented film which is superior in stability at a high temperature and in life, by applying the mixture of an alkyl alkoxysilane having a long chain alkyl group and a methyl hydrogen polysiloxane onto a film and heating it to perform the orientation treatment in respect to the oriented film where liquid crystal molecules are oriented vertically. CONSTITUTION:A transparent conductive film 2 is provided on a glass substrate 1, and an orientation control film 3 is formed on this film 2, and a liquid crystal layer 4 where liquid crystal molecules are preliminarily oriented vertically is held between these substrates 1, thus obtaining a liquid crystal display element. A toluene mixed liquid of a long-chain alkyl alkoxy silane and a methyl hydrogen polysiloxane is applied to orientation control films 3 brought into contact with the liquid crystal layer 4 to perform the orientation treatment. Heat-treated films 5 are provided by heating at 150-200 deg.C. By these films 6, various liquid crystals are oriented very well in comparison with the use of conventional Na<+> ion barrier layers 6 used on the surface of an SiO2 film.

Description

[Detailed description of the invention] This f! J is concerned with liquid crystal display elements that utilize alignment deformation of liquid crystal molecules that is caused by setting liquid crystal molecules in a −1 orientation state in advance and changing the intensity of electric field, magnetic field, heat, etc. Regarding alignment film.

Conventionally, the method of aligning liquid crystal molecules t-vertically uses a surfactant such as lecithin or hexadecyltrimethylammonium bromide as a substrate. 11, or mixing it with a liquid crystal material is known. However, in this method, the alignment treatment agent is likely to be liberated, so there are problems in terms of high-temperature stability of liquid crystal alignment and longevity.

In addition to the above, there are conventional silane coupling agents b, which are made by coating an organic chromium complex on a substrate and causing a reaction.

A method of causing liquid crystal molecules to be t-oriented is also known. This method is more advantageous than the above-mentioned method using a surfactant in terms of stability as an element.

There are drawbacks such as the following (I) (If) (To).

(1) In order to obtain a good alignment film, K requires the above-mentioned processing agent to be deposited only in a single layer on the substrate surface, there are many restrictions on coating conditions, and reproducibility is poor.

(Although the orientation deteriorates if two or more layers are attached) ω) Chromium complexes still have problems in terms of pollution.

Among the above problems, a method of adding tetraalkoxysilane to the silane coupling agent has been proposed as a method that seems to be a solution to the problem in item (1). However, when using this method, K
Well, I'm suffering from the negativity of orientation.

In order to prevent an increase in leakage current due to the life characteristics of the am* child,
This is especially necessary for devices using ester-based liquid crystals, which require vapor deposition of magnesium septate, tantalum oxide, etc. Therefore, the moldability is poor.

The purpose of the present invention is to eliminate the above-mentioned drawbacks of the prior art and to
It has excellent fabric properties, does not lose its alignment ability during the heating process during cell assembly, has excellent alignment properties for various liquid crystals, and has no leakage during long weather tests and humidification tests even during the device life. The object of the present invention is to provide a highly reliable alignment film with almost no increase in current.

The present invention has been made in this regard, and is applied as an alignment treatment agent for a substrate surface that comes into contact with liquid crystal.

Alkylalkoxysilane having a long chain alkyl group (A
S) Methyl hydrogen polysiloxane CH5)
Alternatively, it is characterized by using an alignment film coated with a mixture with a polysilmethylene compound (AlI3) and heat-treated at 150° C. or higher.

In the nine alignment treatment agents shown above, long-chain alkyl alkoxysilane (As) has the following general formula structure Rs: C
2t to C24 normal alkyl group R1e Rs:
Ct~C4 alkyl group methylhydrodienepolysiloxane (H5) Ka÷5i-0÷ ・・・・・・・
Song (2) 1 n: Natural number, C's meaning d 1oooo or less. The polysylmethylene compound (MS) is the following -R,:C1-C
The alkyl group or phenyl group of 4 rlL = natural number, preferably 10,000 or less.The compound of formula (1) may be used in a single layer or in a mixture of two or more ates. The same applies to the compounds of formulas (2) and (3) above.

The alkoxysilane represented by the above formula (1) and the above (8
) or the mixture of the alkoxysilane represented by the above formula (1) and the polysylmethylene represented by the above formula (3), the si atomic ratio "t" ”SiCES)
/Si CAS): Q, 1 to 8, SiCMS
VSi CAS>: A range of 0.2 to 10 is good in terms of liquid crystal orientation. In addition, liquid crystal orientation outside the above range is ! This is not good because the 1iIl orientation cannot be obtained.

The solvent for the composition according to the present invention is not particularly limited as long as the alkoxysilane and methylhydrodiene polysiloxane or polysilmethylene are dissolved at the same time; Alcohols such as ethyl cellosolve, polyhydric alcohol derivatives such as butyl cellosolve, and the like are useful because of their excellent solubility and coating properties. The blending ratio of the former is preferably within a range that does not impair coating properties and liquid crystal orientation, and generally the former is 80 to 99.9 wt%,
The latter 20~r: J1wt%.

Note that the alignment treatment agent is applied onto the substrate by a coating method such as a dip, spinner, or spray method, and then heat-treated in a dry atmosphere at 150° C. or higher, preferably 150° C. to 250° C. from the viewpoint of alignment stability. By doing so, an alignment film can be obtained, but
This is due to the reaction described below.The coating film described above can be formed by low-cost methods such as printing, shows very good alignment with various liquid crystals, and has a very good lifespan. be.

The present invention will be explained below using examples.

Example 1 As shown in Table 1, a long chain alkyl alkoxysilane and a methylhydrodiene polysiloxane having a molecular weight of about 1000 were combined. Using toluene as a solvent, the amount of the sum of long-chain fulkylalkoxysilane and meffi, hydrogen polyaxane relative to the solvent is 2 wt%. Using this solution, a transparent conductive layer H2 of, for example, indium oxide is selectively formed and spin-coated onto a glass substrate 1, as shown in FIG. This was heat-treated for 200 CI hours to form an alignment film 3.
shall be. The thickness of this alignment film is approximately αOOS μm. After that, maintain the distance between the boards at 8^m.

Liquid crystal 4t-sealed with adhesive 5. This substrate provided good homeotropic alignment for various nematic liquid crystals. Even when various cholesteric liquid crystals are used, good homeotropic distribution is achieved.

direction was obtained.

This orientation effect can be achieved by using epoxy adhesive at 150°C2.
The time was maintained even after the device assembly process.

The life of the device using the above substrate is determined by weather test and 70°C.
Even after about 200 hours in the 95% fat humidification test, there was almost no increase in leakage current, which was good.

Table 1 - Vertical alignment of liquid crystal ◯: Good △: Slightly poor Example 2 As shown in Table 2, a long chain alkyl alkoxysilane and methylpolysilmethylene having a molecular weight of about 800 were combined. Using toluene as a tU agent, the amount of the sum of long-chain alkyl alkoxysilane and methylpolysylmethylene relative to the solvent is:
It is 2wt%.

Using this solution, assemble and examine the device in the same manner as in Example 1.
Similar results as in Example 1 were obtained.

Liquid crystal vertical alignment ○: Good Δ: Slightly poor*: Mixture of methylpolysylmethylene and long-chain alkyl alkoxysilane (#S) CAS 160'O phenylpolysilmethylene was combined. Toluene is used as a solvent, and the amount of the sum of long-chain alkyl alkoxysilane and 7-enylpolysylmethylene is 2 wt% relative to the solvent.

Using this liquid, an element was assembled in the same manner as in Example 1 and an elbow test was performed, and the same results as in Example 1 were obtained.

Liquid crystal vertical alignment O: Good Δ: Slightly poor*: Phenylpolysylmethylene (MS) and long chain alkyl alkoxy (
As) Mixture of silanes The various liquid crystals here include Schiff base liquid crystals.

Biphenyl liquid crystal Azooxy liquid crystal, azo liquid crystal, ester liquid crystal, phenylcyclohexane liquid crystal, phenylpyridine liquid crystal, and cholesteric liquid crystal obtained by adding an optically active substance to the above nematic liquid crystal.Furthermore, there is no liquid crystal such as dichroic dye. These liquid crystals, including mixed liquid crystals to which substances have been added, include those with positive and negative anisotropy of electric conductivity, and both were investigated.

According to the present invention, it is possible to obtain a practical-level single-direction alignment film that is excellent in orientation and display performance and has good life characteristics.

It becomes possible to produce liquid crystal display elements with new functions such as color display.

Liquid crystal display elements that require high-quality alignment include two-color display systems manufactured by cholesteric-nematic transition, and Flex-Ya (manufactured by birefringence field effect).
There are display methods such as a hybrid orientation-induced birefringence field effect display method, a dynamic scattering display method, and an orientation vibration display method.

However, it goes without saying that the present invention is effective not only in these display systems but also in all systems that require a strong orientation in the initial state III (unexcited state, N14).
Cholesteri, ri, ne, chi in %.

Compared to the currently mainstream twisted nematic field effect display system, the transition type two-color display system requires no polarizing plate, has lower product costs, and can display any color using dichroic dyes. This method has some advantages and is likely to become mainstream in the future, but in this method, liquid crystal molecules t-! Keeping the liquid crystal molecules in the -1 alignment state has the advantage that the driving voltage can be lowered compared to the case where the liquid crystal molecules are kept in the homogeneous alignment state.

[Brief explanation of drawings]

FIG. 1 shows the basic configuration of the above-mentioned device using the liquid crystal alignment film of the present invention, and FIGS. 2 and 3 show Nα+ ions formed entirely by oxides such as 5dJ2 on the surface of the glass substrate in contact with the liquid crystal. FIG. 2 is a cross-sectional view of an element in which a barrier layer is provided to further enhance alignment ability. 1...Glass substrate 2...Transparent conductive film 5...
・Orientation control film 4...Liquid crystal layer 5...Adhesive 6...Na+ ion barrier layer

Claims (1)

[Scope of Claims] t. A liquid crystal sandwiching substrate that sandwiches a liquid crystal to form a liquid crystal holding element, comprising an alkyl alkoxysilane having a long-chain alkyl group on the side of the substrate in contact with the liquid crystal and a methylhydrodiene polysiloxane. A mixture or a mixture of an alkyl alkoxysilane having a long-chain alkyl group and polysylmethylene is coated with a heat-treated film obtained by heating the mixture at 150°C to 200°C. Liquid crystal display element. 2. The alkylalkoxysilane having a long-chain alkyl group has the structure of the following general formula (1) and Rt: '
11~C normyl alkyl group R,,R,:C,~C
The alkyl group methyl hydride i-diene polysiloxane of No. 4 has the structure shown in the following general formula. The liquid crystal display element according to claim 1, wherein the polysylmethylene compound has a structure represented by the following general formula (3). Base m: natural number