JPS6029726A - Liquid crystal display body - Google Patents

Abstract

PURPOSE:To improve flexural resistance and durability of liquid crystal display body made of a flexural substrate comprising plastic film, etc. by executing sealing to have dual structure with specified two kinds of sealing material. CONSTITUTION:Peripheral parts of plastic substrates 1, 1' comprising polyester resin film, etc. are sealed; the inside of the peripheral part contacting with the enclosed liquid crystal layer 2 is sealed 3 with a sealing agent (e.g. epoxy adhesive) having low water permeability, and a sealed part 4 comprising a sealing agent (e.g. silicone adhesive) having high adhesion to the substrate is provided to the outside of the sealed part 3. (5 is a sealed part; 6 is a gap material). By constructing, as described above, the sealed part to have a dual structure, penetration of gas and moisture into the liquid crystal at the inside sealed part 3 is prevented, moreover, both substrates 1, 1' are firmly bonded at the outside sealed part 4 without spoiling flexibility of both substrates.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a liquid crystal display using a flexible substrate such as a plastic film.

[Prior art]

Conventionally, proposals have been made to manufacture flexible liquid crystal display bodies using plastic substrates, but thermosetting epoxy resins that have a low reaction effect on liquid crystal compositions such as those used for ordinary glass substrates have been proposed. When used as a sealant for the above-mentioned plastic liquid crystal display, the adhesion to the plastic substrate is weak due to the lack of flexibility of the resin, so it is easy to peel off during processes such as assembling a large number of large substrates at the same time and then cutting them. etc., the reliability as a flexible display body was low.

On the other hand, when a flexible adhesive with high peel strength such as silicone or urethane is used for the sealing part, the silicone adhesive has high gas permeability and water vapor permeability, so pressure bubbles inside the liquid crystal layer may occur during durability tests. However, urethane-based adhesives have the disadvantage of being easy to form, and urethane-based adhesives have a large reaction influence on liquid crystal compositions, resulting in a short lifespan of liquid crystal displays.

〔the purpose〕

The present invention solves these drawbacks, and aims to ensure the lifespan and bending test resistance of liquid crystal displays using flexible substrates such as plastic substrates, and to facilitate production. The liquid crystal display of the present invention has a double-layered sealing structure, in which the first sealing side in contact with the liquid crystal is made of a resin with low water permeability, and the second sealing material on the outside thereof is flexible. It is made of resin that has strong adhesion to the substrate.

As an example of the second and first sealing materials, the second sealing material is used to strongly bond the flexible substrates to each other using a silicone adhesive, and the first sealing material, which serves as the liquid crystal inside, is bonded using an epoxy adhesive. It may be used as a drug. Epoxy adhesives have low reactivity with liquid crystal compositions and have very low gas permeability and moisture permeability. Furthermore, silicone adhesives have a high peel strength against flexible substrates such as plastic films, and can strongly bond flexible substrates together.

In such a double-structured sealing part, the second sealing material strongly adheres the flexible substrates to each other, and the first sealing material prevents gas and moisture from passing into the liquid crystal. .

Further, in the double seal portion, the seal on the liquid crystal side may be made of a resin that does not easily react with the liquid crystal, and the outer seal material may be made of a resin with low water permeability. In this case, as an example of the sealing material, the sealing material on the liquid crystal side is a silicone resin, and the outside thereof is an epoxy resin. The epoxy adhesive has a low reaction influence on the liquid crystal composition, and its gas permeability and moisture permeability are extremely low, ensuring reliability as a display.

Furthermore, silicone adhesives have high peel strength against plastic films and ensure the mechanical strength of the display.

Examples of the flexible substrate include polyester resin, cellulose resin, bolyate/'sulfon resin, polysulfone resin, acrylic resin, polyethylene terephthalate resin, phenoxy resin, and films made of the above resins. There are also multi-layered products made of the above resins and films. Other flexible substrates include the above-mentioned branutic resin and PVA film that contains a dichroic dye and has polarizing ability, and a polarizing plate type in which this PVA film and cellulose acetate film are laminated and integrated. In addition to a substrate in which a polarizer made of a K film is laminated together, a polarizing plate itself made of the above material, for example, is used.

Further, aluminum foil or an aluminum plate may be attached to one side, or aluminum QM or silver may be vapor-deposited or coated.

The thickness of such a substrate is approximately 0.025-15 mm.

When the liquid crystal display is intended to be shaped like a book, a thickness of about 0.025 mm to 1 mm is preferable. Further, a thickness of approximately 0.05 to 0.02 mm is suitable. [Example 1] FIG. 1 shows a plan view of the liquid crystal display of the present invention, and FIG. 2 shows a cross-sectional view. In FIG. 1, 1.1' is a plastic substrate, 2 is a liquid crystal composition, a sealed portion with a three-layer epoxy adhesive, and 4 is a sealed portion with a silicone adhesive. Further, 5 is a sealing agent that covers the liquid crystal injection port portion, and 6 is a gap agent for maintaining the liquid crystal layer thickness evenly at -Vc. By forming the sealing portion into a double structure as shown in d1 above, the silicone adhesive can compensate for the lack of adhesion strength to plastic films, which is a drawback of the epoxy adhesive. Furthermore, the silicone adhesive shown in FIG. 1 does not necessarily have to be continuous in the form of a bag, and even if it is continuous as shown in FIG. 3 or FIG. 4, it can sufficiently function.

On the other hand, the structure shown in Figure 1, in which the Nubesa part with a liquid crystal composition of K 11 is made of silicone adhesive, and the outer part made of epoxy adhesive, has good reliability and also maintains considerable strength. be done. However, when subjected to a strong bending test, it is easy to get damaged from the ends, and its strength is inferior to that of the above-mentioned structure.

As a method of forming the double structure of the seal part mentioned above,
Screen-print epoxy adhesive on one board and clean-print KFi silicone adhesive on the other board, then combine the two boards and heat to harden the adhesive. A double structure can be formed.

[Example 2] A polyether sulfonate film with a thickness of 100 μm was used as a plastic film substrate, and an indium oxide-tin oxide based transparent conductive N film with a thickness of about 500 μm was formed thereon by low-temperature sputtering. Next, predetermined turns were formed by photolithography, an alignment agent was applied thereon, and after firing, the turns were rubbed in a predetermined direction with gauze.

Next, screen print epoxy adhesive on one substrate, clean print KVi silicone adhesive on one substrate, sprinkle spacers, then combine the two substrates and heat to harden the adhesive. I let it happen. This cell was filled with a liquid crystal substance by vacuum injection, and the injection port was sealed with a room temperature curing epoxy adhesive [7].

FIG. 5 shows the bending resistance of the cell thus produced. The number of durability varies depending on the bending radius, but when bent to a radius larger than 100 #Im, it has a durability of more than 10,000 times, which is a practical level. It can be seen that this result is much better than that of a structure with only epoxy seal.

In addition, if the seal part is composed of a double seal in which the sealing material on the liquid crystal layer side is silicone-based resin and the outer sealing material is epoxy-based resin, the characteristic curve in Figure 5 has the characteristics shown by the dotted line. It shows characteristics that are between the points close to and the solid line characteristic curve, and the characteristics are better than those in which the seal part is made of only epoxy resin, but they are not as good as those with the opposite configuration. In addition, the liquid crystal does not react with the seal, and the sealing material on the outside of the double seal prevents moisture and harmful substances from entering the liquid crystal, making it difficult for the liquid crystal to deteriorate.

Although the electric camellia and the alignment film are omitted in the drawings, an electric contact is formed on the substrate, and an alignment film of a predetermined thickness is laminated thereon and subjected to alignment treatment.

〔effect〕

As explained above, the plastic liquid crystal display with a double seal as in the present invention has high reliability during bending, no peeling of the upper and lower films during the 4 ft process, and is flexible and high quality. It is possible to stably produce high-quality liquid crystal displays.

[Brief explanation of drawings]

1 and 2 show a plan view and a sectional view of an embodiment of the invention. 5 and 4 show plan views of another embodiment. FIG. 5 shows the durability of a liquid crystal display according to an embodiment of the present invention during a bending test. 1.1' ... Upper and lower substrates 2 ... Liquid crystal layer 3 ... Sealing part (epoxy resin) 4,, 4Z
41'...Seal part (silicon resin>5.
... Sealing Department and above Applicant Epson Corporation Agent Patent Attorney Mogami Mufu

Claims (2)

[Claims] (1) In a liquid crystal display comprising at least a liquid crystal layer, a pair of flexible substrates that sandwich the liquid crystal layer, and a sealing part, the sealing part is connected to a first sealing material on the liquid crystal layer side and a sealing material on the outside thereof. The second sealing material has a double structure, and the second sealing material is made of a resin that has strong adhesion to the substrate, and the second sealing material is made of a resin that has low water permeability. A liquid crystal display. (2) the second sealing material is made of silicone resin;
1. According to claim 1, the first sealing material is an epoxy resin. F? Crystal display.