JPH0223317A - Liquid crystal display element - Google Patents

Abstract

PURPOSE:To eliminate the disorder of the orientation of liquid crystal due to the cohesion of spacer particles by carrying out a surface treatment for metal oxide particles by using at least one material selected among a titanium coupling agent, a silane coupling agent, and zircoaluminate. CONSTITUTION:An oriented film 3b on a transparent electrode substrate7 contains metal oxide particles 4, whose surfaces do not contact liquid crystal directly. The surfaces of the metal oxide particles 4 are treated with at least one surface treating agent selected among the titanium coupling agent, silane coupling agent, and zircoaluminate. Thus, the surfaces on the metal oxide particles 4 as spacers are treated. Consequently, spacer do not cohere, but are dispersed in the oriented film 3b, so the orientation disorder due to the cohesion of the spacers is eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to liquid crystal display elements. More specifically, the present invention relates to a liquid crystal display element that eliminates alignment film alignment of ferroelectric liquid crystal caused by agglomeration of spacer particles filled in the alignment film.

[Technical Background of the Invention J1- and Prior Art] Liquid crystal display elements conventionally used in watches, computer word processors, etc. have, as their basic structure, two transparent electrode substrates with an alignment film provided on the transparent electrodes. A negative conductor has a structure in which the liquid crystal is placed with the alignment film on the inside and the liquid crystal is sealed between them. Generally, in a liquid crystal display element, it is necessary to align the liquid crystals in a certain direction, that is, to align them, so in the above liquid crystal display element, an alignment film is provided to align the liquid crystal molecules.

In addition, in order to maintain a constant width of the gap (cell gap) between two opposing transparent electrode substrates, these liquid crystal display elements are made using glass fibers, glass beads, plastic beads, and metal oxide particles. etc. are often placed as spacers between both transparent electrode substrates. Since the spacer is provided between both transparent electrode substrates, it is present within the liquid crystal layer within the shell. However, when the spacer comes into direct contact with the liquid crystal, the surface of the spacer does not have the ability to align the liquid crystal like the surface of an alignment film, which causes the alignment of the liquid crystal to be disturbed at the interface between the liquid crystal and the spacer.

This alignment film deviation of the liquid crystal becomes significant, especially in the case of a ferroelectric liquid crystal display element using a ferroelectric liquid crystal that is difficult to align uniformly.

As a means to solve the above-mentioned problems,
Publication No. 36224 discloses that at least one of two transparent electrode substrates each having an alignment film provided on a transparent electrode has an alignment film containing a spacer, and the two transparent electrode substrates have an alignment film on the inner side. A liquid crystal display element is disclosed in which liquid crystal is sealed between two layers. In such a liquid crystal display element, the spacer does not come into direct contact with the liquid crystal, and only the surface of the alignment film comes into contact with the liquid crystal, so that the alignment of the liquid crystal is not disturbed from the interface between the liquid crystal and the spacer.

The alignment film of such a liquid crystal display element is formed by applying an alignment film forming material chamber 15 liquid in which particles serving as a spacer material are dispersed onto a transparent electrode substrate and heat-treating the liquid.

However, since it is difficult to sufficiently disperse the particles in this coating liquid, there is a drawback that particles agglomerate in the formed alignment film.

Therefore, although conventional liquid crystal display elements containing spacers in the alignment film can eliminate alignment film failure at the interface between the liquid crystal and the spacer, alignment film failure caused by agglomeration of the spacers poses a new problem. Become.

[Summary of the Invention] An object of the present invention is to provide a liquid crystal display element that eliminates alignment film failure of liquid crystal due to aggregation of spacer particles filled in the alignment film.

The above object of the present invention is that at least one of two transparent electrode substrates each having an alignment film on a transparent electrode has an alignment film containing metal oxide particles, and A liquid crystal display element in which an electrode substrate is arranged with an alignment film inside and a liquid crystal is sealed therebetween; the metal oxide particles are selected from the group consisting of a titanium coupling agent, a silane coupling agent, and a zircoaluminate. A liquid crystal display element characterized in that the surface is treated with at least one selected surface treatment agent can be achieved.

That is, the present invention provides a liquid crystal display element containing, as a spacer, metal oxide particles surface-treated with at least one of a titanium coupling agent, a silane coupling agent, and a zircoaluminate in an alignment film. It is something to do.

In the liquid crystal display element of the present invention, the metal oxide particles serving as spacers are surface-treated, so that the spacers do not aggregate with each other but are dispersed and present in the alignment film. Therefore, there is no alignment film sagging caused by agglomeration of spacers.

Preferred embodiments of the present invention are listed below.

(1) The surface treatment agent substantially contains a molecule having at least one atom (group) selected from the group consisting of halogen, vinyl group, mercapto group, epoxy group, amino group, imino group, and impropenyl group. A liquid crystal display element characterized in that it contains as a component.

(2) A liquid crystal display element, wherein the surface treatment agent is a silane coupling agent.

(3) The metal oxide particles are silicon oxide (silica),
A liquid crystal display element comprising particles of at least one metal oxide selected from the group consisting of aluminum oxide (alumina), tungsten oxide, and titanium dioxide.

(4) A liquid crystal display element characterized in that the metal oxide particles described in IF are silicon oxide (silica).

(5) The average particle diameter d of the primary particles of the metal oxide particles is
A liquid crystal display element characterized in that 1.2 μm≦d≦6 μm.

(6) lii A liquid crystal display element, wherein the liquid crystal is a ferroelectric liquid crystal.

[Configuration of the Invention] The configuration of the liquid crystal display element of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a sectional view showing an example of the liquid crystal display element of the present invention. Transparent electrodes 2a, 2b, on transparent substrates 1a, lb,
The alignment films 3a and 3b are stacked in this order to constitute a transparent electrode substrate 6.7. Transparent electrode substrate 6.7
are arranged so that alignment films 3a and 3b face each other, and liquid crystal 5 is sealed between them. Transparent electrode substrate 7
The upper alignment film 3b contains metal oxide particles 4, so that the surface of the metal oxide particles 4 does not come into direct contact with the liquid crystal. In the liquid crystal display element of the present invention, the surface of the metal oxide particles 4 is treated with at least one surface treatment agent selected from the group consisting of a titanium coupling agent, a silane coupling agent, and a zircoaluminate. It is characterized by being metal oxide particles.

In the liquid crystal display element of the present invention, the metal oxide particles serving as spacers are surface-treated, so that the spacers do not aggregate with each other but are dispersed and present in the alignment film. Therefore, there is no alignment film tearing caused by aggregation of spacers.

The liquid crystal display element of the present invention includes not only the features shown in FIG. 1 but also all the features that are used in ordinary liquid crystal display elements, such as providing an electrical insulating layer, using a color filter, and providing a polarizing plate. It is possible.

The metal oxide that is the spacer material used in the liquid crystal display element of the present invention varies depending on the liquid crystal used, alignment film material, cell gap setting, etc., but representative examples include silicon oxide (silica), aluminum oxide ( (alumina), tungsten oxide, titanium oxide, etc. Among these, silicon oxide (silica) is the most preferred because it is easy to handle and has an appropriate particle size.

The particle size of the metal oxide particles varies depending on the liquid crystal used, alignment film material, cell gap setting, metal oxide used, etc., but is preferably from 1.2 μm to 6 μm.

The surface treating agent for surface treating the metal oxide particles is selected from titanium coupling agents, silane coupling agents and zircoaluminates. Among these, the silane coupling agent is the most preferred surface treating agent because of its good stability when surface treating silica, which is the most preferred metal oxide. In addition, atoms selected from the group consisting of halogen, vinyl group, mercapto group, epoxy group, amino group, imino group, and isopropenyl group (
A surface treatment agent containing as a substantial component a molecule having at least one group) can provide more effective surface treatment to metal oxide particles than one that does not have these molecules. Therefore, it is a preferred surface treatment agent.

Remaining 11 Specifically, a surface treating agent containing the following molecules as a substantial component is preferred.

C1l□<ll5IC,123,C112-CH5i(
OC2H5) a to 1h=clIsi (OC21140
LII:+)3C)13 (:1I2-CCOC3116Si (OCIL+)3
)1□NCJ4NIII: JrS i (OCIl+
)3C11゜112N(:J4NIIC3116S!(OCt13
)z]1□NC3+11;Sl (OC2)16):+
, Ca115NtlCtllaS! (OCI
Ii) 3! l5CJeSi(OC113):+,C
D, C+HaSi (OCI+3) 3 As the glass substrate, transparent electrode, and liquid crystal used in the liquid crystal display element of the present invention, known ones conventionally used in liquid crystal displays [7' can be used.

For example, a float glass with good smoothness can be used as a glass substrate, and indium oxide (In2) can be used as a transparent electrode.
o3), tin oxide (SnO2) and ITO (indium tin oxide).

Of course, the liquid crystal display element of the present invention is effective for obtaining good liquid crystal alignment even when using TN liquid crystal or STN liquid crystal, but the effect of the present invention is most effectively exhibited by ferroelectric This is a liquid crystal display element using a synthetic liquid crystal. As the ferroelectric liquid crystal, conventionally known ones can be used.

Specifically, the liquid crystals having margin-conducting properties are chiral smectic C phase (SmC"), H phase (SmH"), and 1 phase (SmH").
ml”), J phase (SmJ”), Ni phase (SmK”)
, G phase (SmG'') or F phase (SmF'').

For example, the following molecules are used as ferroelectric liquid crystals.

Alternatively, CN el+3 A specific liquid crystal composition is C5-10 manufactured by Chisso ■.
11, C5-1013, C3-1015, ZLI-3488, ZLI-3489 manufactured by Merck, Teikoku Kagaku Sangyo ■
HS-98P, HS-78P (both product names)
Examples include, but are not limited to, the following. There is no problem in adding dichroic dyes, viscosity reducers, etc. which are soluble in the liquid crystal to these liquid crystals.

Further, the alignment film material is appropriately selected depending on the liquid crystal used, but is preferably at least one organic polymeric substance selected from the group consisting of polyvinyl alcohol, gelatin, polyimide resin, polyamide resin, and polyester resin. The thickness of the alignment film also varies depending on the liquid crystal used, but is preferably 200 to 2000.

Next, a method for manufacturing the liquid crystal display element of the present invention will be described.

In manufacturing the liquid crystal display element of the present invention, metal oxide particles surface-treated with at least one surface treatment agent selected from the group consisting of a titanium coupling agent, a silane coupling agent, and a zircoaluminate, The alignment film forming material coating liquid dispersed therein is applied onto a transparent electrode substrate and further heat-treated to produce an alignment film containing the spacer.

An example of manufacturing the liquid crystal display element of the present invention will be described below in order.

First, the metal oxide particles of the spacer material are surface treated with a surface treatment agent. This treatment can be carried out, for example, by dispersing and suspending the metal oxide in a solvent, adding a treatment agent to this suspension, and causing a reaction. The metal oxide particles and surface treatment agent used are as described above.

The thus obtained surface-treated metal oxide is added and dispersed in a coating liquid in which the above-described resin for forming an alignment film is dissolved.

On the other hand, the above alignment film forming material coating liquid is applied onto a transparent electrode provided on a transparent substrate by a conventional method. The coating may be applied directly onto the transparent electrode, or an insulating layer may be provided on the transparent electrode and the coating may be applied thereon. The provided alignment film is preferably rubbed with synthetic fibers such as nylon, polyester, and polyacrylonitrile, and natural fibers such as cotton and wool.

A pair of transparent electrode substrates each having at least one of them a transparent electrode substrate made of a transparent substrate, a transparent electrode, and an alignment film containing a spacer, manufactured as described above, are sandwiched between liquid crystals with the alignment film facing inside. Compare it with .

Of course, the liquid crystal display element of the present invention can be provided with structures provided in conventional liquid crystal display elements, such as a polarizing plate, an electrical insulating layer, and a color filter, depending on the purpose of use.

Next, examples of the present invention, comparative examples, and comparative tests between the two will be described.

However, the present invention is not limited to this example.

[Example 1] Silica particles (particle size: 2 μm) Ig manufactured by Catalysts & Chemical Industry ■ were dispersed in 150 g of N-methyl-2-pyrrolidinone, and silane coupling agent KBM4 manufactured by Shin-Etsu Silicone ■ was added to this.
0.5 g of 03 was added, and the mixture was reacted at 110° C. for 1.5 hours with stirring. After the reaction was completed, the mixture was decanted three times with N-methyl-2-pyrrolidinone and then with acetone, and then dried at 80° C. for 1 hour. The surface-treated silica fine particles thus obtained were added to an N-methyl-2-pyrrolidinone solution (2 wt %) of polyimide LX5400 manufactured by E1 Tatekasei ■ at a concentration of 0.0% per 1 g of solvent.
It was added at a ratio of 3 mg and dispersed by ultrasonication.

This solution was applied onto a transparent electrode of a glass substrate using a spin cord, heated at 320° C. for 1 hour, and then rubbed with a polyester cloth. On the other hand, apart from this transparent electrode substrate, an N-methyl-2-pyrrolidinone solution (2 wt%) of the above polyimide LX5400 containing no silica particles was applied on the transparent electrode of the glass substrate in the same manner as above, followed by heat treatment and rubbing. A treated transparent electrode substrate was created. These two transparent electrode substrates were bonded together so that the alignment films faced each other to form a cell.

Ferroelectric liquid crystal C31013 (phenyl ester type) manufactured by Chisso Corporation was injected into this cell at 100℃, and then the temperature was reduced to about ℃.
The liquid crystal display element of the present invention was obtained by slow cooling at a rate of 1/min.

Comparative Example 1 A liquid crystal display element was obtained in exactly the same manner as in Example 1, except that the cosilica fine particles were not subjected to surface treatment.

A comparative test was conducted between Example 1 and Comparative Example 1 described above. First, in order to compare the dispersion of the two spacers,
- The number of aggregates composed of three or more water particles per 1 mm2 was measured.

Comparative Example 1 Table 1 Cell gap (μm) 94 ±0.09 Number of aggregates (pieces/mm2) Approximately 21 Next, in order to compare the state of orientation of both liquid crystals, the cells were observed under orthogonal Nicolization. .

The results are shown in Table 2.

Below is a margin Table 2 Observation results No zigzag defects were observed Example 1 Uniform orientation was observed 1a, 1b
=Glass substrates 2a, 2b: Transparent electrodes 3a, 3b: Alignment film 4: Metal oxide particles 5: Liquid crystal 6.7: Transparent electrode substrate comparative example I Patent applicant where zigzag defects of S number were observed Fuji Photo Film Co., Ltd. Company agent Patent attorney
Hatao Yanagawa As is clear from the above comparative tests 1 and 2, in the liquid crystal display element of the present invention, since the spacer is surface-treated,
Spacers do not form aggregates in the alignment film. Therefore, the alignment film of the liquid crystal caused by agglomeration of the spacers does not occur, and a uniform alignment state of the liquid crystal can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view schematically showing a configuration example of a liquid crystal display element of the present invention.

Claims (1)

[Claims] 1. At least one of two transparent electrode substrates each having an alignment film provided on the transparent electrode has an alignment film containing metal oxide particles, and the two transparent electrode substrates are arranged with the alignment film inside. A liquid crystal display element comprising: a liquid crystal sealed between the metal oxide particles; A liquid crystal display element characterized by being subjected to a treatment.