JPH01243027A - Spacer material for liquid crystal display element and production thereof - Google Patents

Abstract

PURPOSE:To uniformize the cell cap of the liquid crystal display element and to obtain the liquid crystal display element which is made of film substrates and exhibits uniform responsiveness without unequal colors by providing coating layers of an epoxy-modified nylon resin having semi-curable adhesiveness on the surfaces of polymer beads. CONSTITUTION:The epoxy-modified nylon 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 spacer 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, and a method for manufacturing the same.

(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.

In addition, in the method of injecting liquid crystal using a pressure difference between the empty cell container and the external pressure after vacuum evacuation, a phenomenon is observed in which excess liquid crystal enters due to the deflection of 782, 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 that have adhesive properties for these have been devised (e.g., Japanese Patent Application Laid-Open No. 61-83520), but they have poor adhesion to the polyimide alignment film that serves as the adhesive surface of the substrate, so a large amount of spacer agents are required. If it is not enclosed, 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 makes the cell gap uniform in conventional liquid crystal display elements, especially liquid crystal display elements using low rigidity substrates such as plastic films, and achieves uniform response without color unevenness. As a result of research into a spacer agent that would allow the upper and lower substrates to be bonded together in order to obtain the film-substrate liquid crystal display element shown in the figure,
By coating the surface of a conventional polymer bead spacer agent with an epoxy-modified nylon resin that has good adhesion to polyimide using a mechanochemical method or an interfacial reaction method, a spacer agent with strong adhesive properties can be obtained. Based on this knowledge, we conducted various studies and completed the present invention.

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

The epoxy-modified nylon resin used as an adhesive in the present invention includes 2 to 50 parts by weight of epoxy resin and 50 parts by weight of nylon resin.
~98 parts by weight, and the epoxy resin has two or more epoxy groups in one molecule, such as glycidyl ether type such as bisphenol type epoxy resin and novolak type epoxy resin, aromatic epoxy, cycloaliphatic type epoxy, etc. The ester type, ether ester type, or glycidylamine type is used.

The preferred nylon resin is one that can dissolve 2% or more in methanol at temperatures above room temperature and below the boiling point, such as nylon 6,
Copolymers such as nylon 66, nylon 610, or nylon 11 are used, such as Bratamide H105 manufactured by Dr. Brate, Seidel 6 and 63 manufactured by DuPont.

The mixing ratio of epoxy resin and nylon resin is preferably in the range of 98 to 50 parts by weight, corresponding to 2 to 50 parts by weight of epoxy resin. If the ratio of epoxy resin is greater than this range, the adhesiveness will decrease and the nylon resin will If the ratio is too large, the resulting spacer agent is insufficient in terms of heat resistance and liquid crystal resistance. In addition, dicyandiamide is added to the epoxy resin as necessary.
Curing agents such as diaminodiphenylsulfone may also be used.

As a solvent for the adhesive, methanol, benzyl alcohol, trichloroethylene, acetone, toluene, ethylene glycol monomethyl ether, acetic acid ethylene glycol monomethyl ether, and mixtures thereof can be used.

This method involves coating the surface of polymer beads with the epoxy-modified nylon resin obtained in this way.
First, surface modification was performed using a mechanochemical method.

First, the B-stage fine particles of this adhesive, preferably a particle size of 2t! Fine particles of n~0.1 am are created. 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 mm, 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 epoxy-modified nylon 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 form an adhesive layer on the surface of the polymer beads.

Specifically, an uncured epoxy-modified nylon resin is emulsified with water using an emulsifier.

To form an emulsion, uncured epoxy-modified nylon resin containing an emulsifier is heated and stirred at high speed, and water is gradually added to form an emulsion.

In addition to adding the above-mentioned curing agent, thermosetting polymer beads such as benzoguanamine resin spheres, cross-linked polystyrene resin spheres, etc. having a uniform core particle size of around 10 mm are added to form an emulsion. The particles are hardened onto the surface of the parent particles and separated from the water using filtration, centrifugation or the like. After drying, a spacer agent having a coating layer of the epoxy-modified nylon 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 solution of Epicoat "828 (manufactured by Shell) as an epoxy resin and Seidel 61 (manufactured by DuPont) as a nylon resin dissolved in a mixed solvent of methanol/benzyl alcohol (80/20) was mixed at a ratio of 4:6. An epoxy-modified nylon resin adhesive was obtained.

This was dried at 130°C, then ground and classified using a jet mill to obtain B-stage fine particles with an average particle diameter of about 1. This was coated onto spherical benzoguanamine resin particles having an average particle diameter of 10 square meters using a hybridization system (Yinara Kikai Seisakusho) by adjusting the mixing ratio so that the film thickness was 1-.

The resulting spacer agent was evenly distributed on a transparent film substrate for a liquid crystal display element at a rate of approximately 200 pieces per CD, and the upper substrate was stacked and thermocompression bonded at 160°C to create a TN (twisted nematic) mode liquid crystal display element. As a result, there was no bulge in the substrate when the liquid crystal was injected, and a uniform gap thickness was obtained over the entire area, and when the liquid crystal was driven, a good display was obtained.

<Example 2> DER542 (manufactured by Dow Chemical Company) as epoxy resin
A solution in which 30 parts by weight of nylon resin was dissolved in 40 parts by weight of methyl ethyl ketone was mixed with a solution in which 70 parts by weight of Seidel 63 (manufactured by DuPont) as a nylon resin was dissolved in a mixed solvent of 400 parts by weight of methanol and 100 parts by weight of triclene. death,
An adhesive solution was obtained. To this was added an ether type or ester type nonionic surfactant as an emulsifier, and while heating and stirring at high speed, water was added little by little to form a W10 type emulsion. By adding more water, O
/ Phase inversion to W-type emulsion. At this time, high-speed stirring was continued to make the particles fine and uniform, and a curing agent of dicyandiamide was added thereto, as well as spherical benzoguanamine resin particles having an average particle size of 10 or so as a matrix. In this way, a spacer agent was prepared in which an adhesive layer of epoxy-modified nylon resin was formed on the surface of the core polymer beads, and the spacer agent was incorporated into a liquid crystal display element, and the result was good.

<Comparison Example> B-stage epoxy resin particles (average particle size 1:lzm) and spherical benzoguanamine resin particles with an average particle size of 10 tln were placed on a transparent plastic film substrate at approximately 200 mL per IC.
After measuring and dispersing the moisture, the upper substrate was stacked and thermocompression bonded at 150° C., but the upper and lower substrates were not bonded together.

Therefore, when 300 to 400 pieces were dispersed per 1 c1j, 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 polymer bead spacers, 6 is a liquid crystal, and 7 is an epoxy-modified nylon resin adhesive. 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 the precision of the gap layer when used alone, so they are used together with polymer beads, and the amount of adhesive particles is quite large, causing a decrease in contrast. Although there were defects such as causing 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 epoxy-modified nylon resin having semi-curable adhesive properties on the surface of polymer beads. (2) A method for producing a spacer agent for a liquid crystal display element according to claim 1, characterized in that the epoxy-modified nylon resin is coated using a mechanochemical method. (3) Claim 1 characterized in that the epoxy-modified nylon resin is coated using an interfacial reaction method.
A method for producing a spacer agent for a liquid crystal display element as described in 2.