Stock material or miscellaneous articles – Web or sheet containing structurally defined element or... – Adhesive outermost layer
Reexamination Certificate
2000-03-01
2002-03-19
Seidleck, James J. (Department: 1711)
Stock material or miscellaneous articles
Web or sheet containing structurally defined element or...
Adhesive outermost layer
C428S354000, C428S3550AC, C428S515000, C428S313900, C522S120000, C522S182000, C427S516000
Reexamination Certificate
active
06358606
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an acrylic pressure-sensitive adhesive double coated tape or sheet, an acrylic non-substrate pressure-sensitive adhesive transfer tape or sheet, and a method for manufacturing the same, and more particularly, to an acrylic pressure-sensitive adhesive double coated tape or sheet having good adhesive strength, holding power, and heat resistance, an acrylic non-substrate pressure-sensitive adhesive transfer tape or sheet having good adhesive strength, holding power, and heat resistance, and a method for manufacturing the same.
2. Description of the Prior Art
In an electric and electronic industry, a building and civil engineering industry, and an automobile industry, or the like, as higher performance and higher functionality of products and a variety of products have been required, the need for an adhesive or a pressure sensitive adhesive having high heat resistance, high adhesive capability, high reliability has been growing.
In recent years, in particular, from the viewpoint of improving workability and working environment, there has been an increase in the number of cases where various parts are bonded with the use of a tape-like or sheet-like pressure-sensitive adhesive (“pressure-sensitive adhesive” is hereinafter referred to as “adhesive”) instead of a liquid adhesive. Further, the adhesive tape or sheet is used not only for the use in an interim adhesion but also for the use in a permanent adhesion.
Further, from the viewpoint of easy disposal of wastes, instead of a conventional mechanical bond, the use of an adhesive double coated tape or sheet has increased. There has been expected that an adhesive tape has a comparatively large thickness of, for example, 0.5 mm to 2 mm.
Still further, as parts and apparatuses have been reduced in size, the need for the thickness of an adhesive double coated tape or sheet has become severe and there has also been expected the development of an adhesive double coated tape or sheet having characteristics described above and having no holding member (i.e., no substrate).
As a method for manufacturing an adhesive tape, a method has been adopted in which a solvent type adhesive or such a water borne adhesive as emulsion is applied to a substrate, such as a polyester film, paper, or the like. The solvent is then volatilized by heating to thereby crosslink and cure the adhesive.
However, since the conventional solvent type adhesive tape cured by heating does not have sufficient heat resistance and reliability after bonding, adhesive tapes cured with ultraviolet rays (for example, Japanese Published Unexamined Patent Application No. 63-268784 and Japanese Published Unexamined Patent Application No. 9-137142) have been developed.
However, it is difficult to obtain an adhesive tape having high adhesion and high heat resistance at the same time, and good workability such as thick coating performance, curing performance with ultraviolet rays, or the like. Hence, the development of a material or a process for solving this problem has been desired.
An object of the present invention is to solve the above problems of the prior art and to provide an adhesive tape or sheet having high adhesive strength, holding power, heat resistance, and good workability such as thick coating performance, curing performance with ultraviolet rays, and a method for manufacturing the same.
SUMMARY OF THE INVENTION
In order to accomplish the above mentioned object, the present invention presents a pressure-sensitive adhesive double coated tape or sheet having a three-layer structure comprising an adhesive layer, a substrate layer and an adhesive layer, each of which is manufactured by the use of a light-cured adhesive whose main components are a (metha)alkyl ester acrylate monomer, a polar functional group containing monomer, an acrylic polymer having a photo-active functional group, and a photopolymerization initiating agent, wherein the acrylic polymer having a photo-active functional group has an average molecular weight of 200,000 to 3,000,000 and the content of the photo-active functional group is 0.001 milli-equivalent/g to 0.5 milli-equivalent/g.
In this case, the adhesive forming the adhesive layer is a light-cured adhesive whose main components are the (metha)alkyl ester acrylate monomer, the polar functional group containing monomer, the acrylic polymer having a photo-active functional group, and the photopolymerization initiating agent. The adhesive forming the substrate layer is a light-cured adhesive comprising the adhesive forming the adhesive layer and inorganic hollow particles added thereto.
Further, the present invention presents a method for manufacturing a pressure-sensitive adhesive double coated tape or sheet having a three-layer structure comprising an adhesive layer, a substrate layer, and an adhesive layer, the method comprising the steps of:
applying the above mentioned light-cured adhesive to a sheet substrate to form the adhesive layer;
applying the above mentioned light-cured adhesive to the adhesive layer to form the substrate layer;
applying the above mentioned light-cured adhesive to form the adhesive layer; and
applying light to the adhesive layer, the substrate layer, and the adhesive layer to cure the three layers at the same time.
Still further, the present invention presents a non-substrate pressure-sensitive adhesive transfer tape or sheet manufactured by the use of a light-cured adhesive whose main components are a (metha)alkyl ester acrylate monomer, a polar functional group containing monomer, an acrylic polymer having a photo-active functional group, and a photopolymerization initiating agent, wherein the acrylic polymer having a photo-active functional group has an average molecular weight of 200,000 to 3,000,000 and the content of the photo-active functional group is 0.001 milli-equivalent/g to 0.5 milli-equivalent/g.
Still further, the present invention presents a method for manufacturing a non-substrate pressure-sensitive adhesive transfer tape or sheet, the method comprising the steps of:
applying the above mentioned light-cured adhesive to a sheet substrate to form an adhesive layer having a thickness of 10 &mgr;m to 2000 &mgr;m; and
applying light to the adhesive layer to cure it.
According to the present invention, a pressure-sensitive adhesive double coated tape or sheet having excellent heat resistance, adhesive strength, holding power, and in particular, excellent holding power at high temperatures can be obtained and can well be manufactured in mass production because it is excellent in thick coating performance and curing performance by ultraviolet rays.
DETAILED DESCRIPTION OF THE INVENTION
In order to accomplish the object described above, the inventors have investigated various kinds of materials and processes and have found the fact that a pressure-sensitive adhesive double coated tape or sheet, which is made by applying a light-cured adhesive whose main components are a (metha)alkylester acrylate monomer, a polar functional group containing monomer, an acrylic polymer having a photo-active functional group, and a photopolymerization initiating agent to a sheet substrate and by applying light thereto to polymerize it, has high adhesion, high holding power, high heat resistance and further good workability such as thick coating performance, curing performance by ultraviolet rays, and the like.
It was found that an acrylic polymer having an average molecular weight of 200,000 to 3,000,000 and a photo-active functional group content of 0.001 to 0.5 milli-equivalent/g functioned well as an acrylic polymer having a photo-active functional group. It was verified that a pressure-sensitive adhesive double coated tape or sheet made by the use of a light-cured adhesive containing this acrylic polymer showed excellent adhesive characteristics.
In other words, the use of the above mentioned light-cured adhesive makes it possible to produce an adhesive tape having excellent heat resistance, adhesive strength, holding power (in particular, h
Masuda Akiyoshi
Nate Kazuo
Sakai Takahiro
Bagwell Melanie D.
Birch & Stewart Kolasch & Birch, LLP
Seidleck James J.
Sliontec Corporation
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