Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From silicon reactant having at least one...
Reexamination Certificate
2000-02-22
2001-05-29
Moore, Margaret G. (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From silicon reactant having at least one...
C528S031000, C525S431000, C525S474000, C525S476000, C525S477000, C524S538000, C524S540000, C524S588000
Reexamination Certificate
active
06239245
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
Not applicable.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not applicable.
REFERENCE TO A MICROFICHE APPENDIX
Not applicable.
FIELD OF THE INVENTION
This invention is directed to a resin additive that consists of a powdered silicone rubber, a curable resin composition that contains this powdered silicone rubber additive, and a cured resin that is obtained by curing the composition. More particularly, the invention is directed to a resin additive able to impart superior thermal shock resistance even in the case of resins that have absorbed moisture, a curable resin composition capable of forming a cured resin that has superior thermal shock resistance even after absorbing moisture, and a cured resin that has superior thermal shock resistance even after absorbing moisture.
BACKGROUND OF THE INVENTION
Numerous problems have been encountered by users of cured resins obtained by curing curable resin compositions, even though the electric characteristics such as the dielectric characteristic, the volume resistivity, and the insulation breakdown strength, as well as the mechanical characteristics such as bending strength, compressive strength, and impact strength, of such cured resins may be superior. For instance, when such resins are used as sealing agents for electric or electronic parts, repeated thermal shock results in the generation of gaps between the sealing resin and the part, or results in the generation of cracks in the sealing resin. This often occurs because the coefficient of thermal expansion of the resin is much greater than that of the electric or electronic part. Further, the part itself may be destroyed so that there occurs a conspicuous drop in the reliability of such parts.
Several solutions have been proposed for endowing cured resins with flexibility. In this regard, reference may be had to certain curable resin compositions of powder obtained by pulverizing silicone rubber containing linear organopolysiloxane blocks in the amount of 10 weight percent or greater, as in Japanese Patent Application Kokai No. Sho 58-219218; certain curable resin compositions of powdered silicone rubber which contain linear organopolysiloxane blocks in the amount of 10 weight percent or greater obtained by curing silicone rubber compositions in an aerosol state in a hot air draft, as in Japanese Patent Application Kokai No. Sho 59-96122; and certain curable resin compositions of powdered silicone rubber obtained by curing silicone rubber compositions in a disperse state in water, as in either Japanese Patent Application Kokai No. Sho 64-4614 or Japanese Patent Application Kokai No. Sho 64-51465.
However, even in these cases, the thermal shock resistance of resins obtained by curing the composition, has been insufficient, especially thermal shock resistance following the absorption of moisture.
BRIEF SUMMARY OF THE INVENTION
It is therefore an object of the invention to provide (i) a resin additive which is able to impart superior thermal shock resistance even in the case of resins that have absorbed moisture, (ii) a curable resin composition that is capable of forming a cured resin that has superior thermal shock resistance even after absorbing moisture, and (iii) a cured resin that has a superior thermal shock resistance even after absorbing moisture.
The resin additive is an additive powder with a mean particle size of 0.1 to 100 &mgr;m which has been prepared from a silicone rubber having a moisture absorption rate of 0.20 weight percent or less, after having been treated for 20 hours at a temperature of 121° C., a pressure of 2 atmospheres, and relative humidity of 100 percent. The curable resin composition is a composition that contains the resin additive, and the cured resin is a resin obtained by curing the curable resin composition.
These and other features of the invention will become apparent from a consideration of the detailed description.
REFERENCES:
patent: 5492945 (1996-02-01), Morita et al.
patent: 58-219218 (1983-12-01), None
patent: 59-096122 (1984-01-01), None
patent: 01004614 (1989-01-01), None
patent: 01051465 (1989-02-01), None
Furukawa Haruhiko
Kobayashi Kazuo
Morita Yoshitsugu
Ueki Hiroshi
DeCesare James L.
Dow Corning Toray Silicone Company, Ltd.
Moore Margaret G.
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