JPH08146433A - Spacer for liquid crystal display - Google Patents

Abstract

PURPOSE: To obtain the spacer not binding liq. crystal molecules regularly in the surface direction of the spacer and excellent in productivity and performance stability by using the spacer for a liq. crystal display with the surface roughened. CONSTITUTION: The surface of the spacer for a liq. crystal display is roughened by finely scratching the surface irregularly. Namely, the roughening is performed by mixing the spacer consisting of polymer grain with the ceramic grain, metallic grain and the glass fiber pieces used for the spacer and agitating the mixture. The glass fiber pieces are most adequately used in this case. The regular arrangement of the liq. crystal molecules in the spacer surface direction is avoided by the irregular scratches on spacer surface, and the molecules are positioned in the random directions with respect to the spacer surface. Consequently, the light leakage from around the spacer is prevented, and a liq. crystal display excellent in contrast is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display spacer, and more particularly to a liquid crystal display spacer made of polymer particles.

[0002]

2. Description of the Related Art In liquid crystal displays, spacers are used to control the distance between two glass substrates facing each other, that is, the thickness of a liquid crystal layer. As the spacer, spherical polymer particles are often used because they follow the expansion of the liquid crystal due to the temperature change of the environment.

Since the spacer is arranged in the liquid crystal layer between the glass substrates, it becomes a foreign substance for the liquid crystal material. Therefore, the alignment of the liquid crystal molecules regulated by the alignment film may be regulated by the spacer, and only the liquid crystal around the spacer cannot be controlled by turning the voltage on and off. In particular, liquid crystal molecules that are regularly bound to the surface direction of the spacer deteriorate the contrast as light leakage around the spacer in the dark field state.

Japanese Patent Application Laid-Open No. 4-264427 discloses that a composite particle in which fine particles are attached to the surface of spherical particles (spacer) is used as a spacer for solving this problem. In the spacer using the composite particles, the alignment of the liquid crystal around the spacer is disturbed by the fine particles adhering to the surface of the spherical particles, and the liquid crystal molecules are not regularly bound in the surface direction of the spacer. Avoid worsening.

[0005]

However, the spacer using the above-mentioned composite particles makes the manufacturing process very complicated, and fine particles adhering to the surface of the spherical particles fall off during use, resulting in display defects. May induce.
The present invention has been made by paying attention to the problems as described above, and on the condition that the liquid crystal molecules are not regularly bound to the surface direction of the spacer, the productivity is excellent, An object of the present invention is to provide a spacer for a liquid crystal display that does not cause a state change and has excellent performance stability.

[0006]

In order to achieve the above-mentioned object, the spacer for a liquid crystal display according to the present invention is characterized in that its surface is roughened. This roughening causes irregular fine scratches on the spacer surface, and the roughening treatment is performed by mixing the spacer made of polymer particles with ceramic particles, metal particles, glass fiber pieces for spacer use, and stirring. Good. The most suitable mixture in this mixing and stirring is a glass fiber piece.

The material of the spacer is not particularly limited as long as it is a resin, and examples thereof include a styrene / divinylbenzene copolymer and a benzoguanamine / melamine / formaldehyde condensate. Generally, the spacer has a particle size of 3 to 15 μm. The glass fiber is also used for spacers and the fiber diameter may be about 1 to 10 μm.

The rough surface treatment for forming irregular scratches on the spacer surface is carried out by appropriately mixing IPA and water with the spacer and the glass fiber in a ratio of 1: 1 to 4: 1 and stirring or sonicating. It may be dispersed with a washer. If the degree of scratches provided on the spacer surface is too small, the effect will be small, and if it is too large, the mechanical strength of the spacer will be reduced.
It may be controlled appropriately by changing the mixing ratio of the spacer and the glass fiber, the stirring time, and the like.

[0009]

[Operation] Roughening of the spacer surface causes irregular scratches to be formed on the spacer surface, which prevents the liquid crystal molecules from being regularly arranged in the spacer surface direction, and the liquid crystal molecules are not aligned on the spacer surface. You will be bound in a random direction. As a result, light leakage around the spacers is prevented, and a liquid crystal display with excellent contrast can be obtained. Here, the method of aligning or constraining the liquid crystal molecules is to form a scratch on the spacer surface. If the direction of the scratch is irregular, the direction in which the liquid crystal molecules are constrained is also irregular. It is obvious even considering so-called rubbing processing.

[0010]

【Example】

[Examples ~] For each Example ~, styrene
Divinylbenzene copolymer spacer (6 μm diameter) and 6
Glass fibers having a diameter of μm were mixed at a ratio shown in Table 1, IPA (isopropyl alcohol) and water were added, and the mixture was dispersed in an ultrasonic cleaner for the time shown in Table 1. After that, the spacer is taken out by centrifugation, and the liquid crystal panel (90 ° twist cell) is composed of the following components.
Then, the light leakage around the spacer was observed. The results of this observation are shown in Table 1.

Glass substrate: 50 mm square × 1.1 t surface polishing soda lime ITO: 20 Ω / □ Aligning agent: Nissan Chemical SE-150 film thickness 0.1 μ
m Liquid crystal: Merck ZLI-2293 Chiral agent: Merck C-15 Sealing agent: Mitsui Toatsu Structbond

[Comparative Example] A liquid crystal panel (9) having the same structure as that of the example without using the spacer (6 μm diameter) of the styrene / divinylbenzene copolymer as it is, that is, without roughening treatment
It was installed in a 0 ° twist cell), and light leakage around the spacer was observed. The results of this observation are shown in Table 1.

[Comparative Examples-] A spacer of styrene / divinylbenzene copolymer (diameter of 6 μm) and glass fiber of diameter of 6 μm were mixed, and Table 1 for each Comparative Example-
IPA and water were added in the proportions shown in Table 1 and dispersed in an ultrasonic cleaner for the time shown in Table 1. After that, the spacer was taken out by centrifugation and incorporated into a liquid crystal panel (90 ° twist cell) having the same structure as that of the example, and the light leakage around the spacer was observed. The results of this observation are shown in Table 1.

[0014]

[Table 1]

In Table 1, ∘ indicates a small amount of light leakage, Δ indicates a slight amount of light leakage, × indicates a large amount of light leakage, * indicates that light leakage is suppressed, but some spacers are destroyed, and # indicates a spacer. Shows that the mechanical strength of the cell deteriorates and unevenness occurs in the cell gap. Furthermore, when SEM observation of these spacers was carried out, irregular scratches were formed on the surface of all of the spacers of the example compared with the comparative example (untreated product). From the above results, it is possible to provide a spacer with less light leakage by changing the mixing and dispersion conditions of the spacer and the glass fiber.

[0016]

As can be understood from the above description, according to the spacer for a liquid crystal display of the present invention, the spacer for a liquid crystal display has irregular scratches on the surface due to the roughening of the surface. Therefore, it is possible to prevent the liquid crystal molecules from being regularly arranged in the spacer surface direction due to the scratches, prevent light leakage around the spacer from occurring, and provide a liquid crystal display excellent in contrast.

The spacer for a liquid crystal display according to the present invention does not require a complicated manufacturing process because the surface may be roughened by mixing and agitating it with ceramic particles, metal particles, glass fiber pieces and the like. It is excellent in productivity and prevents the liquid crystal molecules from being regularly arranged in the spacer surface direction due to scratches on the spacer surface. It does not change and has excellent performance stability.

Claims (1)

[Claims] 1. A spacer for a liquid crystal display, wherein the surface of the spacer used for the liquid crystal display is roughened.