JPH01243028A - Spacer material for liquid crystal display element and production thereof - Google Patents

Abstract

PURPOSE:To uniformize the cell gap of the liquid crystal display element and to obtain the liquid crystal display element which is made of film substrates and exhibits the uniform responsiveness without unequal colors by providing coating layers of an amino-modified polyester resin having semi-curable adhesiveness on the surfaces of polymer beads. CONSTITUTION:The amino-modified polyester resin having the good adhesiveness to polyimide is coated on the surfaces of spacer materials 4, 5 consisting of the polymer beads by a mechanochemical technique or interfacial reaction method. The adhesive agents 7 of the surface coating layers of the space materials 4, 5 adhere securely to the oriented films of the polyimide if the spacer materials 4, 5 obtd. in such a manner are used and, therefore, the upper and lower substrates 1 do not bulge and dent. The uniform gap is thereby obtd. even with the large-area glass or film substrates 1. The large-area liquid crystal display element which is free from the unequal colors and exhibits the uniform response speed without exerting adverse influence on the liquid crystal 6 is thus obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a spacer agent for uniformizing the gap between upper and lower substrates of a liquid crystal display element.

(Prior technology) Glass fibers and polymer beads have traditionally been used as spacers for liquid crystal display elements, but none of them have adhesive properties on their own, and are effective in resisting forces that compress the substrate. However, it had no effect on forces that widened the gap thickness. Therefore, when creating a large-area liquid crystal display element using a glass substrate or a liquid crystal display element using a plastic film substrate, if the upper and lower substrates are warped as shown in Figure 3, the spacer agent in step 5 is used to create gaps due to the warpage of the substrate. occurs and is useless. In the figure, 1 and 2 are glass or plastic film substrates, 3 is a sealant, 4 and 5 are spacer agents, and 6 is a liquid crystal. Furthermore, in the method of injecting liquid crystal using a pressure difference between the empty cell container and the external pressure after vacuum evacuation, there is a phenomenon in which excess liquid crystal enters due to deflection of the substrate, causing the liquid crystal display element to swell as shown in Figure 3. This may cause a decrease in response speed or uneven display.

In addition, these conventional spacer agents do not have adhesive properties themselves, so they easily move within the liquid crystal.
Due to the process of attaching polarizing plates and the subsequent compression of the substrate by pressing it with your fingers, the spacer agent gathers in one place, making the gaps between the liquid crystal display elements uneven, resulting in defects such as uneven color and uneven response. This caused a decline in display quality.

Spacer agents (for example, Japanese Unexamined Patent Application Publication No. 81-83520) that have adhesive properties for these have been devised, but they have poor adhesion to the polyimide alignment film that forms the contact surface of the substrate, so a large amount of spacer agents are required. If you do not include it, it will not be effective,
It has not yet been put into practical use because it causes disclination (alignment defect) of liquid crystals and reduces contrast.

(Problems to be Solved by the Invention) The present invention aims to uniformize the cell gap of conventional liquid crystal display elements, especially liquid crystal display elements using substrates with low rigidity such as plastic ink film, and to achieve uniform response without color unevenness. In order to obtain a film substrate liquid crystal display element that exhibits high properties, we conducted research to find a spacer agent that would allow the upper and lower substrates to be bonded together.As a result of our research, we developed an amino-modified surface agent that has good adhesion with polyimide on the surface of the conventional polymer bead spacer agent. They discovered that a spacer agent with strong adhesiveness could be obtained by coating polyester resin using a mechanochemical method or an interfacial reaction method.Based on this knowledge, they conducted various studies and completed the present invention. This is what led to this.

(Means for Solving Problems) The present invention is a spacer agent for a liquid crystal display element, characterized by having a coating layer of an amino-modified polyester resin having semi-curable adhesive properties on the surface of polymer beads.

The amino-modified polyester resin used as an adhesive in the present invention mainly contains a combination of terephthalic acid and ethylene glycol and/or tetramethylene glycol, and further contains 5 to 50% of isophthalic acid and/or sebacic acid and polytetramethylene ether glycol. This is an adhesive composition in which a polyfunctional aziridine compound is added as a curing agent to a terminal carboxylic acid polyester composition copolymerized in weight%. In addition to this composition, polyfunctional epoxy compounds, polyfunctional cyanate ester compounds, etc. can also be added.

In the method of coating the surface of polymer beads with the amino-modified polyester resin thus obtained, first, the surface was modified by a mechanochemical method.

First, B-stage fine particles of this adhesive, preferably fine particles with a particle size of 2 to 0.1, are prepared. Regarding this method, the adhesive may be obtained by drying the adhesive in a drying oven and then pulverizing with a mill or the like, or it may be granulated by methods such as spray drying or high-speed stirring, or a mixture of both methods may be used.

These adhesive fine particles are sprinkled onto thermosetting polymer beads such as benzoguanamine resin spheres, cross-linked polystyrene resin spheres, etc., with a uniform particle size of around 10 beads, using a mixing and dispersing action. A mixture state is formed, and mechanical and thermal energy due to impact is applied to the particles to form a film, thereby obtaining an adhesive layer of amino-modified polyester resin.

If the particle size distribution of the particles after film-forming treatment is too wide to be suitable for use, it is also possible to uniformize the particle size distribution by wet or dry classification.

Although the spacer agent of the present invention can be obtained as described above, it is also possible to use an interfacial reaction method as shown below as a coating method.

This interfacial reaction method involves adding a water-soluble curing agent to an uncured adhesive emulsion and adding polymer beads to obtain an adhesive on the surface of the polymer beads.

Specifically, an uncured amino-modified polyester resin is emulsified with water using an emulsifier.

To make an emulsion, uncured amino-modified polyester resin containing an emulsifier is heated and stirred at high speed, and water is gradually added thereto to make an emulsion. In addition to adding the above-mentioned curing agent thereto, cured resin spheres with a uniform core particle size of around 10 mm, such as benzoguanamine resin spheres, are added.
Thermosetting polymer beads, such as cross-linked polystyrene resin spheres, are added to harden the emulsion particles onto the surface of the core host particles, which are then separated from the water by filtration, centrifugation, or the like. After drying, a spacer agent having a coating layer of the amino-modified polyester resin of the present invention is obtained.

A cross-sectional view of the spacer agent obtained as described above is shown in FIG.

This is sprinkled on a glass or film substrate, in fact, on a rubbed polyimide alignment film, and the upper substrate is superimposed and thermocompression bonded to harden the adhesive layer on the surface of the spacer agent. A liquid crystal display element is obtained by filling the created void with liquid crystal.

<Example 1> A terminal carboxylic acid with an average molecular weight ff of 110.000, consisting of terephthalic acid, isophthalic acid, and sebacic acid as acidic components in a molar ratio of 4:3:3 and as glycol components as ethylene glycol and tetramethylene glycol in a molar ratio of 1:1. Acid polyester resin with 20% dioxane solution 100%
An amino-modified polyester resin adhesive was obtained by adding 2 parts by weight of trimethylolpropane tri-β and aziridinyl propionate to the weight part. This was dried in a spray dryer at 80°C, then ground in a jet mill,
The particles were classified into B-stage fine particles with an average particle diameter of about 1.

This was coated onto spherical benzoguanamine resin particles having an average particle size of 10 mm using a hybridization system (Nara Kikai Seisakusho) by adjusting the mixing ratio so that the film thickness was uniform.

Approximately 200 spacers were applied to a transparent plastic film substrate for a liquid crystal display element per IC.
TN (
When we created a twisted nematic (twisted nematic) mode liquid crystal display element, we were able to obtain a uniform gap thickness throughout the entire substrate without bulging when the liquid crystal was injected, and when the liquid crystal was driven, a good display was obtained.

<Example 2> Same as Example 1 An amino-modified polyester resin adhesive was obtained.

To this was added an ether type or ester type nonionic surfactant as an emulsifier, and water was added little by little while heating and stirring at high speed to form a W10 type emulsion. By further adding water, the phase is inverted to an OZW type emulsion. At this time, high-speed stirring was continued to make the particles fine and uniform, and a curing agent of an aziridine compound was added thereto, as well as spherical benzoguanamine resin particles having an average particle size of 1O- to serve as a matrix. In this way, an adhesive layer of amino-modified polyester resin was formed on the surface of the spherical benzoguanamine resin serving as the core.

The spacer agent thus obtained was evenly distributed on a transparent film substrate for a liquid crystal display element at a rate of about 200 pieces per CD, and the upper substrate was stacked and thermocompression bonded at 150°C to form a TN (twisted nematic) mode liquid crystal display element. When created, there was no bulge in the substrate when the liquid crystal was injected, a uniform gap thickness was obtained over the entire area, and when the liquid crystal was driven, a good display was obtained.

Comparison Example: B-stage epoxy resin particles (average particle size 13 IEn) and spherical benzoguanamine resin particles with an average particle size of 10 nodes were heated and dispersed on a transparent plastic film substrate at about 200°C per IC, and the upper substrate was stacked and heated at 150°C. When I tried thermocompression bonding, the upper and lower substrates were not bonded together.

Therefore, when 300 to 400 particles were dispersed per CD, they were barely adhered, but when liquid crystal was injected, severe disclination occurred.

(Effects of the Invention) FIG. 1 shows a cross-sectional view of a liquid crystal display element produced using a spacer agent obtained by the method of the present invention.

1 and 2 are glass or plastic film substrates, 3 is a sealant, 4 and 5 are spacers made of polymer beads, 6 is a liquid crystal, and 7 is an adhesive made of amino-modified polyester resin. By using this spacer agent, (a) The adhesive of the surface coating layer of the spacer agent firmly adheres to the polyimide alignment film, so the upper and lower substrates will not bulge or dent, and even large-area glass or film substrates can be used. A uniform gap was obtained, and a large-area liquid crystal display element that exhibited uniform response speed without any color unevenness without adversely affecting the liquid crystal could be obtained.

(b) In addition, conventional adhesive particles do not provide accurate gap thickness when used alone, so they are used together with polymer beads, and the amount of particles is quite large, causing a decrease in contrast. Although there were defects such as causing the occurrence of disclination, the spacer agent of the present invention combines these two elements and has a high adhesive strength, so the disadvantage that only a small amount of spraying is required has been overcome.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a liquid crystal display element using a spacer agent obtained according to the present invention. FIG. 2 is a cross-sectional view of the spacer agent obtained according to the present invention. FIG. 3 is a sectional view showing a conventional liquid crystal display element.

Claims (3)

[Claims] (1) A spacer agent for a liquid crystal display element, comprising a coating layer of an amino-modified polyester resin having semi-curable adhesive properties on the surface of polymer beads. (2) The method for producing a spacer agent for a liquid crystal display element according to claim 1, characterized in that the amino-modified polyester resin is coated using a mechanochemical method. (3) A method for producing a spacer agent for a liquid crystal display element according to claim 1, characterized in that the amino-modified polyester resin is coated using an interfacial reaction method.