JPH10153784A - Spacer for liquid crystal display element, and liquid crystal display element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent generation of a white region around spacer due to abnormal orientations of liquid crystal and to obtain a liquid crystal display element having good display quality, by using a spacer for liquid crystal display element having a specific volumetric resistivity or above. SOLUTION: The spacer 9 for liquid crystal display element has a volumetric resistivity of >=10<15> Ω.cm. Consequently, the electrification property thereof is high and the orientation of liquid crystal molecules having strong polarizable property perpendicular to the surface of the spacer 9 by electrical attraction or repulsion, is made possible, thereby, the abnormal orientation is prevented. In such a case, insulating films 11 are formed respectively on the opposite surfaces of a pair of transparent electrodes 10 and for example, transparent conductive films 12 are patterned and formed by photolithography on the insulating films 11 of the respective substrates 10. Oriented films 13 consisting of, for example, polyimide films, are formed on the transparent conductive films 12 of the respective substrates 10. Next, the spacers 9 for the liquid crystal display element are sprayed on the oriented films 13 of the substrates. Adhesive layers are, thereafter, formed in the peripheral parts on the circumferences of the substrates by using sealing materials 14 to stick the substrates to each other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spacer for a liquid crystal display device and a liquid crystal display device capable of obtaining a liquid crystal display device having good display quality.

[0002]

2. Description of the Related Art Liquid crystal display devices are widely used in personal computers, portable electronic devices and the like. A liquid crystal display element is manufactured by injecting liquid crystal between two bonded transparent electrode substrates. In order to keep the gap between the transparent electrode substrates constant, a spacer is generally used.

In such a liquid crystal display device, it has been known for a long time that the orientation of liquid crystal molecules becomes irregular at the interface between the liquid crystal and the spacer, and the display quality may be degraded. In particular, in a liquid crystal display device using a super twisted nematic liquid crystal (STN liquid crystal) which has been actively used in recent years, such an abnormal alignment phenomenon of the liquid crystal is likely to occur.

When such an abnormal orientation occurs, a white area called light leakage appears around the spacer. If light leakage has occurred from the initial state, the contrast of the liquid crystal display screen is reduced, and the display quality is reduced. In the initial state, there is no light leakage, but when an electric shock or mechanical shock is applied, the liquid crystal display screen partially
For example, when light leakage occurs in the shape of an annual ring or the like, display quality is poor.

The phenomenon of light leakage occurs in the normally black mode normally used for STN liquid crystals because the orientation of the liquid crystal is fixed in the horizontal direction to the spacer surface (electric field direction) at the interface between the liquid crystal and the spacer. It is.
It is known that in order to prevent light leakage, it is effective to vertically align the liquid crystal around the spacer.

JP-A-6-67182 discloses a liquid crystal comprising a polymer obtained by polymerizing a polymerizable monomer or a polymerizable monomer mixture having a dielectric constant (ε) of 3.0 or more at room temperature. A technique for preventing abnormal alignment of liquid crystal using a display element spacer is disclosed.

However, this technique focuses only on the fact that abnormal alignment is caused by a difference in electrical characteristics between the liquid crystal and the spacer, and attempts to solve the problem by vertically aligning the liquid crystal around the spacer. Not a thing,
The performance of preventing abnormal orientation of the spacer itself was not simply represented.

[0008]

SUMMARY OF THE INVENTION In view of the above circumstances, it is an object of the present invention to provide a spacer for a liquid crystal display element which can effectively prevent light leakage, and a liquid crystal display element having good display quality. It is assumed that.

[0009]

SUMMARY OF THE INVENTION The present invention is a spacer for a liquid crystal display element having a volume resistivity of 10 ¹⁵ Ω · cm or more. Hereinafter, the present invention will be described in detail.

The spacer for a liquid crystal display element of the present invention has a volume resistivity of 10 ¹⁵ Ω · cm or more. If it is less than 10 ¹⁵ Ω · cm, the chargeability of the spacer is low and abnormal orientation cannot be prevented.

Here, the volume resistivity ρ is the reciprocal (ρ = 1 / σ) of the electric conductivity σ, and can be expressed by the following equation. ρ = R × (S / L) where R represents electric resistance, S represents cross-sectional area, and L represents
Represents a length.

Since the spacer for a liquid crystal display element of the present invention has a volume resistivity of 10 ¹⁵ Ω · cm or more, liquid crystal molecules having high chargeability and high polarizability are formed on the surface of the spacer by electric attraction or repulsion. Vertical alignment can be performed, whereby abnormal alignment can be prevented.

Examples of the spacer for a liquid crystal display element of the present invention include those in which the surface of fine particles is coated with an organic silane compound so that the volume resistivity is 10 ¹⁵ Ω · cm or more.

As the above-mentioned organic silane compound, for example,
Methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, methyltributoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, ethyltripropoxysilane, ethyltributoxysilane, propyltrimethoxysilane, propyltriethoxysilane, Propyltripropoxysilane,
Propyltributoxysilane, butyltrimethoxysilane, butyltriethoxysilane, butyltripropoxysilane, butyltributoxysilane, pentyltrimethoxysilane, pentyltriethoxysilane, pentyltripropoxysilane, pentyltributoxysilane, hexyltrimethoxysilane, Trialkoxylated alkylsilanes such as hexyltriethoxysilane, hexyltripropoxysilane and hexyltributoxysilane; trihalogenation such as methyltrichlorosilane, ethyltrichlorosilane, propyltrichlorosilane, butyltrichlorosilane, pentyltrichlorosilane and hexyltrichlorosilane Alkylsilane; (tridecafluoro-
Fluorinated alkylsilanes such as (1,1,2,2-tetrahydrooctyl) trichlorosilane and (3,3,3-trifluoropropyl) trichlorosilane.

As a method for coating the above-mentioned organic silane compound, for example, the above-mentioned organic silane compound is dissolved in an appropriate solvent, the fine particles are immersed in the solution, heated, filtered, and dried by heating to obtain the surface of the fine particles. For example, a method of forming a film of an organic silane compound can be used.

The fine particles are not particularly limited, and may be composed of an organic substance or an inorganic substance. These may be colorless and transparent.
It may be colored by an appropriate method.

The fine particles composed of the above organic substances are not particularly limited, and examples thereof include epoxy resins, phenol resins, melamine resins, unsaturated polyester resins, divinylbenzene polymers, divinylbenzene-styrene copolymers, divinylbenzene-acrylates. Examples thereof include copolymers, diallyl phthalate polymers, triallyl isocyanurate polymers, and those composed of a crosslinkable resin such as a benzoguanamine resin. Among them, melamine resin, divinylbenzene polymer, divinylbenzene-styrene copolymer, divinylbenzene-acrylate copolymer,
Those composed of diallyl phthalate and the like are preferred.

The fine particles made of the above-mentioned inorganic substance are not particularly limited. For example, silicate glass, borosilicate glass,
Examples include lead glass, soda-lime glass, alumina, and alumina silicate. Especially, what consists of silicate glass, borosilicate glass, etc. is preferable.

Examples of the colored fine particles include, for example,
Fine particles composed of the above-mentioned organic substances treated with a pigment, carbon black, a disperse dye, an acid dye, a basic dye, a metal oxide, etc .; Or carbonized and colored ones. When the material forming the fine particles itself has a color, it may be used as it is without coloring.

The solvent for dissolving the organic silane compound is preferably a solvent capable of dissolving the organic silane compound and having no active hydrogen that reacts with the organic silane compound. Examples of the solvent include benzene, toluene, and xylene. Aromatic solvents such as hexane, heptane, nonane, and decane; alcohols; mixed solvents of alcohol and water, and the like. In particular, when the organic silane compound has an alkoxyl group, the reactivity is lower than when the compound has a halogen atom.
It is preferable to use a mixed solvent of alcohol and water such as methanol, ethanol, propanol and butanol.

The drying temperature after immersing the fine particles in the organic silane compound solution is preferably 10 to 250 ° C.
If the temperature is lower than 10 ° C., drying takes a long time, and if the temperature is higher than 250 ° C., the spacer may be deteriorated by heat. More preferably, it is 60 to 180 ° C. The heating time at this time is preferably 30 minutes to 10 hours. If the time is less than 30 minutes, the drying is insufficient, and if the time exceeds 10 hours, the spacer may be deteriorated by heat. More preferably, 1
~ 3 hours. When the drying temperature is set low, it is preferable to dry under a reduced pressure of 1 to 5 torr.

In the present invention, in order to improve the adhesiveness between the fine particles and the organic silane compound thin film formed on the surface thereof, and to form a relatively thin organic silane compound thin film uniformly on the surface of the fine particles. Further, a titanium oxide layer may be provided between the fine particles and the coating of the organic silane compound.

The shape of the spacer for a liquid crystal display element of the present invention is not particularly limited, and examples thereof include a true sphere, an elliptical sphere, and a column. When the spacer for a liquid crystal display element of the present invention has a true spherical shape, the diameter is preferably 0.1 to 100 μm. If it is less than 0.1 μm, the gap accuracy of the liquid crystal cell may be reduced, and if it exceeds 100 μm, it may be difficult to obtain a gap in the liquid crystal cell. More preferably, it is 1 to 30 μm.

When the spacer for a liquid crystal display element of the present invention has an elliptical sphere, the short diameter is preferably 0.1 to 100 μm. If the thickness is less than 0.1 μm, the gap accuracy of the liquid crystal cell decreases, and if it exceeds 100 μm, it may be difficult to obtain a gap in the liquid crystal cell. More preferably, 1 to 100
μm. Further, the ratio of the long diameter to the short diameter [(long diameter) / (short diameter)] is preferably 1.05 / 1 to 10/1. If the ratio is less than 1.05 / 1, the long diameter and the short diameter are substantially the same, and the gap accuracy may be reduced.
If it exceeds 0/1, the spacer is likely to break. More preferably, it is 1.05 / 1 to 5/1.

When the spacer for a liquid crystal display element of the present invention has a columnar shape, the diameter of the upper and lower bottom surfaces is preferably 0.5 to 200 μm. If it is less than 0.5 μm, the gap accuracy of the liquid crystal cell may decrease, and if it exceeds 200 μm,
The gap of the liquid crystal cell cannot be obtained. More preferably, 3 to
100 μm. Ratio of height and diameter of cylinder [(height)
/ (Diameter)] is preferably 1/1 to 50/1. 1/1
If it is less than the height, the height and the diameter are substantially the same, and the gap accuracy may be reduced. If it is more than 50/1, the spacer is easily broken. More preferably, 1/1 to 10 /
It is one.

The present invention 2 is a liquid crystal display device using the liquid crystal display device spacer of the present invention 1. The liquid crystal display device of the present invention 2 is, for example, the one shown in FIG.
For example, it is produced as follows.

First, an insulating film 11 made of, for example, SiO ₂ is formed on the opposing surfaces of the pair of transparent substrates 10, respectively, and a transparent conductive film made of, for example, ITO is formed on the insulating film 11 of each of the above substrates. 12 is formed by patterning by photolithography. An alignment film 13 made of, for example, a polyimide film is formed on the transparent conductive film 12 of each of the above substrates. Next, the liquid crystal display element spacers 9 are sprayed on the alignment film 13 on the substrate.

Thereafter, an adhesive layer is formed on the periphery of the substrate facing the above-mentioned substrate using a sealant 14 and bonded to the substrate on which the spacers are scattered.
Is injected between these substrates to form a liquid crystal cell. A liquid crystal display element is obtained by providing wiring in the formed liquid crystal cell.

Spreading density of the spacer 9 for the liquid crystal display element
As 10 to 1000 pieces / mm ^TwoIs preferred. 10
Pieces / mm^TwoIf it is less than the value, no gap of the liquid crystal cell will appear.
1000 pieces / mm^TwoExceeds
The contrast may be reduced due to the laser.

[0030]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Examples 1 and 2 An organic silane compound was dissolved in toluene so that the treatment amount shown in Table 1 was obtained, and organic black fine particles (pigment dispersion type,
Average particle diameter 6.25 μm, standard deviation 0.25 μm) 10
Then, 0 g was immersed and heated in a 55 ° C. water bath with stirring for 1 hour. After filtration, the film was heated in a drier at 180 ° C. for 2 hours under vacuum to form a film of an organic silane compound on the surface of the fine particles, thereby obtaining a spacer for a liquid crystal display device.

Example 3 and Comparative Examples 1 and 2 Uncolored fine particles (Micropearl SPN-206, average particle diameter 6.0 μm, standard deviation 0.24 μm, manufactured by Sekisui Fine Chemical Co., Ltd.) were used as organic fine particles. A spacer for a liquid crystal display element was obtained in the same manner as in Example 1 except that the organic silane compound was used so that the treatment amount shown in Table 1 was obtained.

Using the obtained spacer for a liquid crystal display element,
Evaluation was performed by the following method, and the results are shown in Table 1. Evaluation method (1) Preparation of liquid crystal cell On one surface of a pair of transparent glass plates (50 mm x 50 mm),
SiO by CVD method _TwoA film is deposited, and SiO_Twofilm
Transparent electrode substrate ITO on the entire surface by sputtering
Formed. Further, patterning by etching
Was. A spin core is placed on the ITO film of the pair of transparent glass plates.
Polyimide intermediate (SE-150, Nissan
(Manufactured by Gakusha) and firing at 250 ° C for 30 minutes.
A polyimide alignment film was formed. After this, the upper and lower substrates
The upper and lower liquid crystals are 240 degrees from each other
Rubbing was performed in a direction that would be appropriate.

On one side of this transparent substrate, the obtained spacer for liquid crystal display was added at a ratio of 30 g to 1 liter of a mixed solution of water / isopropanol = 70/30 to obtain a dispersion. After spraying on one side of this transparent substrate so as to have a density of 120 / mm ² , heating and drying,
Peripheral sealant (base agent SE4500, curing agent T, HAVE
N CHEMICAL Co., Ltd.) by screen printing, forming a sealant around the perimeter and bonding both,
It was cured at 160 ° C. for 90 minutes to produce an empty cell. The gap at this time was 6.1 μm. A liquid crystal (ZLI-2293, manufactured by Merck) containing a predetermined amount of a chiral agent was injected into the empty cell thus obtained to prepare a liquid crystal cell, and further heat-treated at 95 ° C. for 30 minutes. .

(2) Light-Emission Property After applying an AC voltage of 80 V for 10 seconds to the liquid crystal cell obtained in this manner, the ratio (%) of the light-emitted spacers among all the scattered spacers was obtained. evaluated.

[0036]

[Table 1]

[0037]

As described above, the spacer for a liquid crystal display element of the present invention has almost no abnormal orientation when used in a liquid crystal display element, and has good light leakage prevention. The liquid crystal display device using the spacer for a liquid crystal display device of the present invention has almost no abnormal alignment (light leakage) and good liquid crystal display quality.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of a liquid crystal display device of the present invention.

FIG. 2 is a diagram schematically showing a liquid crystal display element spacer and liquid crystal molecules of the present invention.

[Explanation of symbols]

 Reference Signs List 8 liquid crystal molecule 9 spacer for liquid crystal display element 10 transparent substrate 11 insulating film 12 transparent conductive film 13 alignment film 14 sealant

Claims (2)

[Claims] 1. A spacer for a liquid crystal display element having a volume resistivity of 10 ¹⁵ Ω · cm or more. 2. A liquid crystal display device comprising the liquid crystal display device spacer according to claim 1.