Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
1999-09-01
2001-03-27
Sikes, William L. (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
C349S158000, C349S098000, C349S117000, C349S112000
Reexamination Certificate
active
06208397
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an optical member of a tacky layer additional provision type capable of being peeled without causing any injury of a liquid-crystal cell at the time of mistaken adhesive bonding, or the like, and excellent in durability of an adhesive state so as to be adapted for formation, or the like, of a liquid-crystal display, and a resin type cell substrate therefor.
The present application is based on Japanese Patent Application No. Hei. 10-267464, which is incorporated herein by reference.
2. Description of the Related Art
An optical material such as a polarizing plate, a phase-difference plate, an elliptically polarizing plate formed by lamination thereof, or the like, used in a liquid crystal display (LCD) is a key device for the LCD. A method of adhesively bonding the optical material to a liquid-crystal cell in a state of an optical member in which a tacky layer of an acrylic type adhesive, or the like, is added in advance to the optical material is used for the purposes of preventing the quality from varying, improving efficiency in assembling the LCD, and so on.
In the above description, if alien substances such as contaminations, air bubbles, etc. are mixed in a portion when the optical member is adhesively bonded to the liquid-crystal cell, the portion causes visibility failure. Accordingly, the optical member must be peeled or released from the liquid-crystal cell because of the mistaken adhesive bonding so that the liquid-crystal cell can be recycled. The mistaken adhesive bonding is generally found in examination steps, or the like, in a process following the adhesive bonding of the optical member. Accordingly, the optical member is generally peeled or released from the liquid-crystal cell when at least several hours have passed after the adhesive bonding. In some cases, the optical member may be peeled or released from the liquid-crystal cell when a month or more has passed.
The background-art optical member, however, had a problem that variations in cell gaps and injuries such as damage of a cell substrate, etc. were caused by the flexibility, or the like, of the cell substrate when the optical member was peeled or released from the liquid-crystal cell using a resin substrate as the cell substrate. If the adhesive force is reduced so that good releasability is given, there arises another problem that peeling or rising occurs in the optical member or marks made by foaming are generated in the adhesively bonded interface because of the influence of moisture and heat when the optical member is used practically for the LCD, or the like.
SUMMARY OF THE INVENTION
An object of the present invention is to develop an optical member which is capable of being peeled without causing any injury of a liquid cell using a resin substrate as a cell substrate and without causing any injury of the cell substrate at the time of mistaken adhesive bonding, or the like, to thereby make it possible to recycle the liquid-crystal cell and which exhibits stable adhesive characteristic in an adhesively bonded state to thereby prevent defects such as peeling, rising, foaming, etc., from occurring even in the case where the liquid-crystal cell is of a thin type or of a large-size type, and to develop the cell substrate therefor.
According to the present invention, there are provided: an optical member including an optical material either one of or each of two surfaces of which is coated with a tacky layer having an initial adhesive force of not smaller than 400 g per 25 mm on the basis of 90° peeling from a resin substrate and having an adhesive force of not smaller than 1000 g per 25 mm after heating at 70° C. for 5 hours; a cell substrate comprising a resin substrate having an initial adhesive force of not smaller than 400 g per 25 mm on the basis of 90° peeling from a tacky layer provided on an optical material and having an adhesive force of not smaller than 1000 g per 25 mm after heating at 70° C. for 5 hours; and a liquid-crystal display wherein such an optical member as described above is adhesively bonded, through a tacky layer of the optical member, to either one of or each of two surfaces of a liquid-crystal cell formed by use of such a cell substrate as mentioned above.
According to the present invention, it is possible to obtain an optical member and a resin type cell substrate, in which, even when the liquid crystal cell using a resin substrate as a cell substrate is thin or large in size, adhesive force is moderate so that the optical member can be peeled or released easily without causing any injury of the liquid-crystal cell and without causing any injury of the resin substrate at the time of mistaken adhesive bonding. Accordingly, the liquid-crystal cell can be recycled. Further, the optical member exhibits stable adhesive characteristic in an adhesively bonded state so that defects such as peeling, rising, foaming, etc. hardly occur. Accordingly, it is possible to obtain a resin type cell substrate therefor; and a liquid-crystal display excellent in quality and durability.
Features and advantages of the invention will be evident from the following detailed description of the preferred embodiments described in conjunction with the attached drawings.
REFERENCES:
patent: 4358494 (1982-11-01), Akimoto et al.
patent: 4387133 (1983-06-01), Ichikawa et al.
patent: 5880800 (1999-03-01), Mikura et al.
Satake Masayuki
Shimodaira Kiichi
Sugawa Hiroshi
Umehara Toshiyuki
Nitto Denko Corporation
Sikes William L.
Sughrue Mion Zinn Macpeak & Seas, PLLC
Ton Toan
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