JPS5924403B2 - lcd cell - Google Patents

Description

[Detailed description of the invention] The present invention relates to a liquid crystal cell.

Generally, a liquid crystal cell is a cell in which a pair of glass substrates with predetermined NESA electrodes formed thereon are arranged facing each other at a predetermined interval, the periphery is sealed, and liquid crystal is sealed in the gap.

In some types of liquid crystal cells, polarizing plates are further placed on the front or front and rear sides of the cell, and when a voltage is applied to the electrodes, the orientation of the liquid crystal molecules changes to produce the desired display. It is configured. As sealing materials for liquid crystal cells used in this manner, inorganic adhesives such as low melting point glass, or organic adhesives such as epoxy resin, cyanoacrylate, and nylon adhesives have been proposed. The selection of these sealing materials is very important in terms of workability, adhesiveness, durability, etc., as well as the influence on the alignment and stability of liquid crystals. Inorganic sealing materials have the advantage of having little effect on liquid crystals and being excellent in durability, but the processing temperature is high (approximately 450° C. or higher), resulting in poor workability. On the other hand, organic adhesives are relatively easy to work with, but there are concerns about their effects on liquid crystals. Among organic adhesives, epoxy resin adhesives have good workability and excellent adhesive strength, but it is known that depending on the curing agent used, it has a negative effect on the alignment and lifespan of liquid crystals. This is also pointed out in Japanese Patent Laid-Open No. 51-120324. The present inventors studied the characteristics of various curing agents and found that phenol novolak resin, which is said to be a curing agent with excellent moisture resistance, is promising. However, it has been found that when a liquid crystal cell sealed with the resin-cured epoxy resin is left at 50° C. for a long time, the current consumption during lighting tends to increase. We believe that this phenomenon is due to impurities that are easily ionically dissociated entering the liquid crystal, lowering the impedance of the liquid crystal, and increasing the apparent current for liquid crystal alignment, and investigated the cause. Based on this knowledge, the present invention provides a liquid crystal cell with good liquid crystal orientation, little change in current consumption, and excellent moisture resistance.

Its feature is that it is a liquid crystal cell in which liquid crystal is filled between two electrode plates arranged opposite to each other and whose peripheral edges are sealed, and an epoxy resin adhesive with a curing agent of phenol novolak resin having 3 or more nuclear elements is used for the seal. It's about using it. In the present invention, as the epoxy resin, for example, bisphenol A type epoxy resin, phenol novolak epoxy resin, polyphenol type epoxy resin, alicyclic epoxy resin, etc. can be used. In addition, the phenol novolak resin with three or more nuclear bodies used as a curing agent has the general formula (wherein R is hydrogen, an alkyl group, a phenyl group, or a 2-(4-hydroxyphenyl) isopropyl group, and n is 1 or more. ).

Next, the present invention will be explained with reference to examples. Example 1 Phenyl 10009, 30% formalin 9209, 4 g of oxalic acid, and 100 g of water are placed in a flask and reacted at reflux temperature for 60 minutes. Next, 2.59 g of hydrochloric acid is added and condensed for 40 minutes.

Then, a large amount of cold water is added to stop the reaction, and the mixture is left to stand for 30 minutes. Next, water is removed using a siphon, and then 120
Leave it at ℃ for 2 hours to dehydrate and take out the produced resin.
The phenol novolac resin synthesized in this manner was well-structured, and it was confirmed by liquid chromatography that the phenol resin of n-0 to 20 and unreacted phenol were mixed together.

Therefore, the above phenolic resin was heated at 150°C and 1mmHg.
The relationship between the standing time, the amount of unreacted phenol, and the amount of phenolic resin with n of 0, 1, and 2 was investigated. The results were as shown in Table 1. These waterfalls 1-6
each resin 249 and bisphenol A with a molecular weight of about 900.
Type epoxy resin 1009, butyl cellosolve 609 1
Mix and stir at 00°C to completely dissolve. Next, the above solution 1009 was taken, 15 g of finely powdered silica was added as a filler, and 10 μm glass fiber 29 was added as a gap control material for the liquid crystal cell, and mixed with a crusher to prepare an adhesive.

The number of each adhesive prepared in this way. /1
Name it 61A~ya6A. Then, a liquid crystal cell was created using these adhesives in the following manner. Adhesive is printed by screen printing around the glass plate with the Nesa electrode and the alignment control film at predetermined positions.

12 "C" After leaving for 1 hour to dry the adhesive solvent, another glass plate with the Nesa electrode and alignment control film was aligned and bonded, and heated at 210°C while applying pressure.
Cure for 2 hours.

Polarizing plates were pasted on the front and back sides of the liquid crystal cell thus created, voltage was applied, and the current consumption of the liquid crystal cell during lighting was measured.

Furthermore, the current consumption of the liquid crystal cell was measured after the liquid crystal cell was left in a constant temperature bath at 50° C. for 1000 hours. The results were as shown in Table 2. From the table, it can be seen that the presence of low molecular weight components such as unreacted phenol and methylene diphenol has a large influence.

As for the characteristics of a liquid crystal cell, the current consumption after the above-mentioned 50°C, 1000 hour life test must be 2.0 μA or less. Therefore, the novolac type phenolic resin used as an adhesive must have three or more nuclear elements. Must be. Similarly,
A system using cresol ethylphenol, p-tertiarybutylphenol, p-phenylphenol, and bisphenol A was used as the raw materials for the phenolic resin.

As a result, it was found that in any case below a binuclear body, the current consumption was adversely affected. Although the truth behind this is not clear, it is related to the reactivity with the epoxy resin, and monomers and binuclear bodies have a low probability of reacting with the epoxy resin and being incorporated into the network structure, and are more likely to remain in the adhesive. It is thought that this is to do so.

Example 2 An epoxy resin adhesive containing the phenolic resin synthesized in Example 1 and another curing agent for comparison was prepared by mixing each material in a crusher according to the composition shown in Table 3.

A liquid crystal cell was prepared using these adhesives in the same manner as in Example 1. The curing conditions for the adhesive at this time are as shown in Table 3. In order to examine the moisture resistance of the adhesive, each of the prepared liquid crystal cells was left in a 6'C, 95% RH atmosphere, and the time until the seal portion of the cell began to peel off was measured.

As a result, in a cell using adhesive A67, which uses phenol novolac resin as a hardening agent, and Taki 8 (Table 3), 500
No peeling was observed even after the passage of time. On the other hand, cells using waterfalls 9, 10, 11 and 12 each have 38
It was cut off at 0 hours, 420 hours, 480 hours, and 360 hours. As described above, epoxy resin adhesives using phenol novolac resin as a curing agent have excellent moisture resistance as sealing materials.

Claims (1)

[Claims] 1. In a liquid crystal cell formed by filling liquid crystal between two electrode plates arranged opposite to each other and sealed at the periphery, a phenol novolac resin having 3 or more nuclear bodies is used as a curing agent, and this is sealed with an adhesive mixed with epoxy resin. A liquid crystal cell featuring