Abrading – Flexible-member tool – per se – Laminate
Reexamination Certificate
1996-12-24
2001-10-09
Hail, III, Joseph J. (Department: 3723)
Abrading
Flexible-member tool, per se
Laminate
C451S534000, C451S538000, C451S539000, C051S293000
Reexamination Certificate
active
06299521
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a polishing sheet for use in grinding, polishing, cutting and otherwise machining metal, lens, semiconductor and liquid crystal substrates and other workpieces.
Prior art polishing sheets are generally classified into polishing sheets, known as grinding stone, obtained by mixing particulate or powdery abrasive grains for grinding, polishing and cutting with a binder and firing the mixture at elevated temperature and polishing sheets obtained by applying a mixture of abrasive grains and a binder onto a support of fabric, paper, film, fiber, non-woven fabric or the like to bind abrasive grains thereon.
All these polishing sheets are used by fixedly securing them to a polishing or grinding tool which can be rotated at a high speed.
All these polishing sheets, however, have the drawback that they do not perform well for polishing or grinding because the instant a high speed rotating polishing sheet is brought into contact with a workpiece, the polishing sheet is sprung off due to the lack of elasticity in a thickness direction. Polishing at a reduced number of revolutions was thus practiced, but this approach was not satisfactory in either polishing efficiency or precision.
As one improvement in this respect, matrixes based on relatively elastic natural rubber or synthetic rubber were sometimes used as a binder for abrasive grains. These matrixes are poor in bond to abrasive grains and heat resistance as a polishing sheet. None of currently available polishing sheets are truly practical.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a polishing sheet which has overcome the problems of prior art polishing sheets during high speed polishing or grinding operation and is improved in polishing efficiency and precision.
In a first embodiment, the present invention provides a polishing sheet comprising a support and an abrasive layer formed thereon with an adhesive layer interposed therebetween, characterized in that,
the adhesive layer is formed by a cured layer of a thermosetting and/or photo-curable adhesive composition based on at least one resin selected from the group consisting of
(A) an ethylene-vinyl acetate copolymer,
(B) a copolymer of ethylene, vinyl acetate, and an acrylate and/or methacrylate monomer,
(C) a copolymer of ethylene, vinyl acetate, and maleic acid and/or maleic anhydride,
(D) a copolymer of ethylene, an acrylate and/or methacrylate monomer, and maleic acid and/or maleic anhydride, and
(E) an ionomer resin in the form of an ethylene-methacrylic acid copolymer whose molecules are bonded by a metal ion.
In a second embodiment, the present invention provides a polishing sheet comprising a support and an abrasive layer formed thereon directly or with an adhesive layer interposed therebetween, characterized in that,
the abrasive layer comprises abrasive grains and a binder which is a thermosetting and/or photo-curable adhesive composition based on at least one resin selected from the group consisting of
(A) an ethylene-vinyl acetate copolymer,
(B) a copolymer of ethylene, vinyl acetate, and an acrylate and/or methacrylate monomer,
(C) a copolymer of ethylene, vinyl acetate, and maleic acid and/or maleic anhydride,
(D) a copolymer of ethylene, an acrylate and/or methacrylate monomer, and maleic acid and/or maleic anhydride, and
(E) an ionomer resin in the form of an ethylene-methacrylic acid copolymer whose molecules are bonded by a metal ion,
the abrasive grains being bound with a cured product of the adhesive composition.
In the second embodiment, it is preferred that the adhesive layer is also formed by a cured layer of either one of the above-defined resins (A) to (E).
In conjunction with a polishing sheet comprising a support and an abrasive layer formed thereon with an adhesive layer interposed therebetween, we have found that when the adhesive layer is formed by a cured product of a thermosetting adhesive composition based on the above-defined resin and preferably containing an organic peroxide as a curing agent (or crosslinking agent), or a photo-curable adhesive composition based on the above-defined resin and preferably containing a photosensitizer as a curing agent (or crosslinking agent), more preferably a thermosetting or photo-curable adhesive composition further comprising a silane coupling agent or an acryloxy, methacryloxy or allyl group-containing compound, there is obtained a polishing sheet which has overcome the above-mentioned drawbacks of prior art polishing sheets and is improved in polishing efficiency and precision. We have further found that similar results are also obtained when the above-defined thermosetting or photo-curable adhesive composition is used as a binder of the abrasive layer. The present invention is predicated on these findings.
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patent: 5573560 (1996-11-01), Kobayashi et al.
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Kotsubo Hidefumi
Morimura Yasuhiro
Bridgestone Corporation
Hail III Joseph J.
Nguyen George
Sughrue Mion Zinn Macpeak & Seas, PLLC
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