JPS58166323A - Production of liquid crystal electrooptic element - Google Patents

Abstract

PURPOSE:To improve the package strength of a titled element by treating the peripheral part of polyester substrate enclosing a liquid crystal with an alkali, and treating the same with a silane coupling agent, then joining the substrate by means of an org. adhesive. CONSTITUTION:Polyethylene terephthalate has good transparency and resistance to solvent, but has poor adhesive strength. The adhesive strength to peeling thereof can be improved without spoiling the transparency by treating the same with a silane coupling agent after an alkali treatment. In the case of using an org. adhesive of polyester, there is no need for the coupling treatment but in the case of using an org. adhesive of epoxy, silicone or urethane, the effect by the coupling treatment is remarkable. The alkali treatment is accomplished by using an aq. soln. contg. 20% NaOH, treating the substrate for 30sec-5min treatment time at 60-80 deg.C, washing the same in tapping water right after the treatment and drying the substrate.

Description

[Detailed description of the invention] The present invention relates to a method for manufacturing a liquid crystal electro-optical element.

In particular, the present invention relates to a method of manufacturing a liquid crystal electro-optical element suitable for improving the package strength of an element using a plastic film as a substrate.

Liquid crystal electro-optical elements have been manufactured using glass substrates, but efforts to use plastic as substrates have been made immediately after the start of research for practical use of liquid crystals. However, the current situation is that it has not yet become a marketable product.

One reason for this is that there was no material that could be used as a suitable plastic substrate. Liquid crystals have such strong dissolving power that they are generally considered to be highly polar solvents, so they dissolve many plastics.

The only film material with good transparency and excellent solvent resistance is polyester resin encased in polyethylene terephthalate (abbreviated as PET). However, polyester resin material has poor adhesive properties, and it is difficult to obtain effective adhesive strength, so liquid crystal cells using polyester resin as the substrate are not commercially available. Not yet. Especially as a substrate for liquid crystal cells.
When a plastic film with a thickness of about 0 to 300 #m is used, a peeling force is applied, which is significantly different from the case of a glass substrate. For members bonded using general KII adhesive, the strength against peeling is the lowest at the adhesive part, and PE
In the case of polyester resin such as T, there is a problem in that the adhesive part peels off with a small amount of force because it has poor adhesive properties.

The present invention has been made to eliminate these problems of the prior art, and an object of the present invention is to provide a method for manufacturing a liquid crystal electro-optical element with improved strength against peeling.

The present invention has found that when a polyester resin film is treated with alkali, the peel adhesive strength is improved without impairing transparency, and furthermore, that the peel adhesive strength is further increased by coupling treatment after the alkali treatment. Results are achieved and friends are achieved.

In the present invention, a preferred embodiment is that the polyester resin film is PET, and that a silane-based coupling agent is used for the coupling treatment.

By subjecting the polyester resin to alkali treatment and coupling treatment, variations in peel adhesion strength are reduced when films are bonded using an organic adhesive, and the reliability of the device can be improved. Furthermore, the types of materials that are effective as organic adhesives can be increased. That is, in the case of only alkali treatment, it is possible to increase the peel strength by using a polyester resin as the organic adhesive, but other organic adhesives do not have a significant effect. However, by performing a coupling treatment after the alkali treatment, the peel strength can be greatly improved even when an epoxy-based, silicone-based, or urethane-based organic adhesive is used.

Examples 1 to 9 Using a polyethylene terephthalate film (Lumirror manufactured by Toshi Co., Ltd.) having a thickness of 250/jm, alkali treatment and coupling agent treatment were performed by the following method.

(1) Alkali treatment: Treatment was performed using a 20% NaOH aqueous solution under varying conditions such that the degree of treatment S was 60 to 80C9 and the treatment time was 30 seconds to 5 minutes, immediately washed with running water, and then dried.

Q) Coupling agent treatment: 1% of r-glycidoxyprobyltrimethoxysilane (A-187 manufactured by Nippon Enika)
After immersing in benzene solution for 1 minute, lift it up for 12 minutes.
Dry at 0r, lb.

After the above-described treatment, a strip test piece with a width of 1611 and a length of 10 was cut out and glued.

Two sheets are pasted together over a length of 551, the adhesion is strengthened, and T
It was subjected to a peeling test. The test was 1 in 25r! The remaining 5 samples were measured. Pulling speed 1
Measurement was made using an autograph manufactured by Shimadzu Corporation at 0+w/-.

The adhesive used is EP-106 (Cemedine).

The curing conditions were 140 tl' and 20 minutes. The test results are shown in Table 1.

Tatami Comparative Example was bonded with EP-106 without alkali treatment or coupling treatment.

Examples 10 to 18 The alkali treatment conditions were fixed at 20% NaOH, 80C, and 1 minute, and the same coupling treatment as in Example 1 was performed, followed by bonding using the adhesive shown in Table 2. Third test result
Shown in the table.

Table 2 Comparative Example 1 The same film used in the example was treated with 20% NaOH, g
oc and treated for 1 minute to prepare 'lj<' adhesive test pieces.

EP-106 was used as the adhesive.

Comparative Example 2 Examples 1 to 9 were prepared for the same film used in Examples.
A T-peel adhesion test piece was prepared by applying only the coupling agent treatment shown in . As an adhesive.

BP-106 was used.

Tt for the test piece of Comparative Example 1.2! <Examples 1 to 9>
Table 4 shows the results obtained using the same method as shown in Table 4.

No. 41!

Claims (1)

[Claims] 1. A method for manufacturing a liquid crystal electro-optical element, which comprises a step of bonding a peripheral substrate covered with a liquid crystal tube substrate and surrounded by liquid crystal, wherein the substrate is a polyester film, and at least four liquid crystals are formed on the substrate. After the surrounding peripheral area is subjected to alkali treatment and then subjected to coupling treatment. 4! Joined using organic adhesive! A method for manufacturing a liquid crystal electro-optical element. 2. The method for manufacturing a liquid crystal electro-optical element according to claim 1, wherein the polyester resin film is polyethylene terephthalate. 3.1￥I The method for manufacturing a liquid crystal electro-optical element according to claim 1, wherein the coupling treatment is Milan coupling treatment. 4. In claim 1, “the organic adhesive is
A method for producing a liquid crystal electro-optical element made of a polyester resin, a urethane resin, a silicone resin, a mixture thereof, or a crosslinked product thereof.