JPH11271736A - Substrate for plastic liquid crystal display element and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance optical characteristics, heat resistance and mechanical strength by sticking a polyether sulfone film having a specified thickness on one face or both faces of an amorphous polyolefin film having specified thickness with a transparent adhesive. SOLUTION: A polyether sulfone film 2 having 25-100 μm thickness is stuck to one face or both faces of an amorphous polyolefin film 1 having 150-300 μm thickness with a transparent adhesive to obtain the objective substrate for a plastic liq. crystal display element having 200-500 μm total thickness. As a preferable morpheme, a gas barrier layer 4 mainly consisting of silicon dioxide, aluminum oxide or magnesium oxide is preferably provided between at least one of the amorphous polyolefin film 1 and polyether sulfone film 2. A transparent electrically conductive thin film 5 made of indium tin oxide is preferably provided on the face of at least one polyether sulfone film 2 which is not in the side of the amorphous polyolefin film 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a substrate material for forming upper and lower electrode substrates used for a plastic liquid crystal display device.

[0002]

2. Description of the Related Art Liquid crystal display devices have been adopted as display devices for portable electronic devices such as calculators, digital watches, pagers, and cellular phones, taking advantage of their features such as thinness, light weight, and low power consumption. A liquid crystal display element is configured by sandwiching liquid crystal between two substrates having transparent electrodes formed on the surface, and arranging a polarizing plate on the outside of the liquid crystal. A conventional substrate uses a 1.1 mm thick glass plate. I have been. Recently, efforts have been made to reduce the thickness of the glass plate in order to further reduce the thickness and weight of the liquid crystal display element. However, as the glass becomes thinner, it becomes extremely fragile, and the target thickness is 0.5 mm or less. In such a case, production becomes difficult, and the product itself also lacks durability. Therefore, attempts have been made to employ a resin substrate instead of glass. A liquid crystal display element using such a resin for a substrate is called a plastic liquid crystal display element (abbreviated as plastic liquid crystal). The plastic liquid crystal uses a film made of resin and is processed by winding and unwinding in a roll-to-roll system (film liquid crystal). There is a device (sheet liquid crystal) which attempts to make effective use of the conventional technology and the device by using the production equipment described above, and this patent relates to a substrate for the sheet liquid crystal.

A sheet liquid crystal substrate needs to have a thickness of 200 μm or more. On the other hand, if it exceeds 500 μm, no problem occurs on the glass substrate, and the necessity is eliminated. Therefore,
The required thickness is a substrate having a thickness of 200 to 500 μm. To use as a substrate of a liquid crystal display element,
It is necessary to satisfy various requirements such as heat resistance and mechanical strength. A polyethersulfone film is promising as a material that satisfies those requirements, and is used as a substrate for film liquid crystal.
When the thickness is 200 μm or more, the yellowish color becomes strong and the birefringence becomes too large to be adopted. On the other hand, as a resin film which is colorless and transparent even at a thickness of 200 μm or more and has low birefringence and good properties, there is an amorphous polyolefin film. In this case, the heat resistance is low and the mechanical strength is inferior. Could not be obtained.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a substrate for a plastic liquid crystal display device having excellent optical characteristics, heat resistance and mechanical strength.

[0005]

SUMMARY OF THE INVENTION The present invention has a thickness of 150 to 150 mm.
A plastic liquid crystal display element substrate in which a polyethersulfone film having a thickness of 25 to 100 μm is bonded to one or both sides of a 300 μm amorphous polyolefin film with a transparent adhesive, and the total thickness is 200 to 500 μm. is there. As a preferred form,
Silicon oxide between at least one of the amorphous polyolefin film and the polyethersulfone film,
A gas barrier layer containing aluminum oxide or magnesium oxide as a main component, a transparent conductive thin film made of indium tin oxide on at least one surface of the polyethersulfone film other than the amorphous polyolefin side, and a gas barrier This is a substrate for a plastic liquid crystal display element having a UV-curable epoxy acrylate-based cured coating layer between a layer and a polyethersulfone film. More preferably, a UV-curable epoxy acrylate-based cured film is provided between the transparent conductive thin film and the polyethersulfone film, and at least one surface has
This is a plastic liquid crystal display substrate having a V-curable epoxy acrylate-based cured coating layer. Furthermore, an amorphous polyolefin film and a polyethersulfone film are manufactured as continuous rolls by a melt extrusion method, bonded together, formed a gas barrier layer, formed a transparent conductive thin film, and formed a UV-curable epoxy acrylate-based cured coating layer. Is also a method of manufacturing a substrate for a plastic liquid crystal display element, which is processed in a continuous roll and then cut into single sheets.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The thickness of an amorphous polyolefin film used in the present invention is 150 to 300 μm. If the thickness is less than 150 μm, the effect of suppressing the deflection of the sheet substrate cannot be obtained. If the thickness exceeds 300 μm, it becomes difficult to wind up the sheet substrate by melt extrusion, and the workability thereafter is also poor. The thickness of the polyethersulfone film used in the present invention is 25 to 100 μm. 2
If it is less than 5 μm, wrinkles are apt to occur, making it difficult to produce by extrusion film forming method, and it is difficult to handle even in subsequent processing. 100
If it exceeds μm, in the case of laminating on one side only, the difference in properties such as thermal expansion from the amorphous polyolefin becomes large, and warpage or deformation occurs during heating, which is not preferable. In the case of laminating on both sides, the yellow color and the birefringence increase, which is not preferable.

An important property as a substrate for a liquid crystal display element is a gas barrier property. Therefore, it is possible to form a gas barrier film on the surface during the process of processing a single sheet into a liquid crystal display element, but the formation of the gas barrier layer is as follows:
It is more efficient and efficient to work in the state of a scroll. Moreover, when formed between the amorphous polyolefin film and the polyethersulfone film, the risk of impairing the gas barrier properties even if the surface is scratched or the like is reduced. In particular, the thinner the film, the more preferably it is carried out in the form of a roll, and the film is preferably formed on the polyethersulfone film side. For the gas barrier layer, a transparent thin film of an inorganic substance which is hardly affected by temperature and humidity is preferable, and a metal oxide thin film containing silicon oxide, aluminum oxide or magnesium oxide as a main component is preferable.

A transparent conductive thin film for forming a transparent electrode is required as a substrate for a liquid crystal display element. This thin film may also be formed during the process of processing a single sheet into a liquid crystal display element. Although it is possible, it is more efficient and efficient to form the transparent conductive thin film in the state of a roll. Also in this case, it is preferable that the film is formed in a roll as the film is particularly thin, and it is preferable that the film is formed on a polyethersulfone film before bonding. It is preferable to use indium tin oxide as the transparent conductive thin film.

[0009] In forming the gas barrier layer on the surface of the polyethersulfone film, if a UV-curable epoxy acrylate-based cured coating layer is formed on the surface of the polyethersulfone film, the adhesion of the gas barrier layer is improved. This is preferable because damage in the bonding step or the like can be prevented. In forming a transparent conductive thin film on the surface of the polyethersulfone film, if a UV-curable epoxy acrylate-based cured film is formed on the surface of the polyethersulfone film, the adhesion of the transparent conductive thin film is improved. This is preferable because damage in a bonding step or the like can be prevented, and conductivity, transparency, and durability as a transparent electrode for a liquid crystal display element are improved.

[0010]

EXAMPLES Example 1 Sumika Excel 4100, a polyethersulfone resin manufactured by Sumitomo Chemical Co., Ltd., was continuously formed into a 50 μm-thick polyethersulfone film by melt extrusion and wound up. The light transmittance is 89% at 600 nm,
It was 88% at 400 nm. The birefringence (retardation) was 5 nm according to the Senarmont compensator method. A resin containing UV-curable epoxy acrylate as a main component was applied to both surfaces of the polyethersulfone film to a thickness of 2 μm by a gravure coating method, and irradiated with ultraviolet rays (UV) to form a cured film. Silicon oxide was formed to a thickness of 1000 angstroms on the cured polyethersulfone film by a vacuum evaporation method to form a gas barrier layer. Further, indium tin oxide was formed on the other cured film surface by a sputtering method so that the surface resistance became 100Ω. An adhesive is applied to the gas barrier layer side of the polyethersulfone film having the gas barrier layer and the transparent conductive thin film, and arton resin manufactured by JSR Corporation as an amorphous polyolefin resin separately prepared by a melt extrusion method is used.
It was bonded to a film having a thickness of 0 μm. The total thickness was 325 μm. Light transmittance is 600n
It was 85% at m and 81% at 400 nm. Birefringence is
It was 5 nm. These optical characteristics can be adopted as a substrate for a liquid crystal display element. In addition, this substrate is 300 mm
The sheet was cut into a single piece of x300 mm and put into an existing production line for a liquid crystal display element for glass substrates, whereby a liquid crystal display element could be produced.

Example 2 50 μm continuously by melt extrusion
A m-thick polyethersulfone film was prepared and wound. The light transmittance was 89% at 600 nm and 88% at 400 nm. The birefringence (retardation) was 5 nm according to the Senarmont compensator method. This film was bonded to the amorphous polyolefin film side using the adhesive of Example 1 at the stage of the roll of the plastic liquid crystal display element substrate of Example 1 before being cut into sheets. The total thickness was 400 μm. The light transmittance was 83% at 600 nm and 79% at 400 nm. The birefringence was 10 nm. These optical characteristics can be adopted as a substrate for a liquid crystal display element. Further, this substrate was cut into 300 mm × 300 mm single sheets, and put into an existing glass substrate liquid crystal display element production line, whereby a liquid crystal display element could be produced. Compared to the substrate of Example 1, the warpage during heating was small, and the workability was improved.

[0012]

According to the present invention, a sheet substrate having a small yellowness and a small retardation required for a sheet liquid crystal can be obtained. Further, it becomes possible to economically form a gas barrier layer and a transparent conductive thin film.

[Brief description of the drawings]

FIG. 1

FIG. 4 is a sectional view of a configuration of a substrate according to the present invention.

[Explanation of symbols]

 1: amorphous polyolefin film 2: polyether sulfone film 3: adhesive layer 4: gas barrier layer 5: transparent conductive thin film 6: UV-curable epoxy acrylate cured film

Claims (7)

[Claims] 1. An amorphous polyolefin film having a thickness of 150 to 300 μm is coated on one or both sides with a thickness of 2
A 5-100 μm polyethersulfone film is laminated with a transparent adhesive, and the total thickness is 200-200 μm.
A substrate for a plastic liquid crystal display element having a thickness of 500 μm. 2. The substrate for a plastic liquid crystal display element according to claim 1, further comprising a gas barrier layer containing silicon oxide, aluminum oxide or magnesium oxide as a main component, between at least one of the amorphous polyolefin film and the polyether sulfone film. . 3. The substrate for a plastic liquid crystal display device according to claim 1, wherein a transparent conductive thin film made of indium tin oxide is provided on at least one surface of the polyethersulfone film which is not on the amorphous polyolefin side. 4. The substrate for a plastic liquid crystal display device according to claim 2, wherein a UV-curable epoxy acrylate-based cured coating layer is provided between the gas barrier layer and the polyether sulfone film. 5. The substrate for a plastic liquid crystal display device according to claim 3, wherein a UV-curable epoxy acrylate-based cured film is provided between the transparent conductive thin film and the polyethersulfone film. 6. A UV-curable epoxy acrylate-based cured coating layer on at least one surface.
A plastic liquid crystal display substrate as described in the above. 7. An amorphous polyolefin film and a polyethersulfone film are produced as continuous rolls by a melt extrusion method, bonded together, formed a gas barrier layer, formed a transparent conductive thin film, and a UV-curable epoxy acrylate-based cured coating layer. The method for producing a substrate for a plastic liquid crystal display element according to claim 1, wherein the substrate is formed into a continuous roll and then cut into sheets.