Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
2002-01-09
2004-11-02
Moore, Margaret G. (Department: 1712)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C427S387000, C524S425000, C524S588000, C528S015000, C528S031000, C528S032000
Reexamination Certificate
active
06811650
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 INVENTION
The present invention relates to an adhesive for silicone rubber that can be readily bonded to silicone rubber materials.
BACKGROUND OF THE INVENTION
Silicone rubber materials are well known as having excellent water repellency, weatherability, heat resistance, and the like properties. Liquid silicone rubbers are used as coating agents or film-forming agents on a variety of substrates. However, these silicone rubbers have poor adhesive properties, and are therefore adapted for use with silicone rubber adhesives. Japanese patent application publication Kokai No. 61-278580, equivalent to U.S. Pat. No. 4,766,193, describes a number of adhesives used with liquid silicone rubbers which comprise organic peroxides, condensation catalysts and organopolysiloxanes having alkenyl groups and hydroxyl or alkoxy groups bonded to silicon atoms.
Japanese patent application publication Kokai 62-90369, equivalent to U.S. Pat. No. 4,889,576, discusses a method of adhering silicone-coated pieces of fabric together by overlapping silicone rubber-coated fabrics and inserting into the overlap region a silicone rubber adhesive. The silicone rubber adhesive is either an addition curing composition containing a platinum-type catalyst or a radical-curing composition containing an organoperoxide type catalyst. The overlap region containing the silicone rubber adhesive is hot-cured during or after press-adhering. In particular, Japanese patent application publication Kokai 62-90369, equivalent to U.S. Pat. No. 4,889,576, discloses a silicone composition that is cured by an addition reaction, but this composition still has inadequate adhesion.
Japanese patent application publication Kokai 10-60281 discloses a silicone composition that contains calcium carbonate powder surface treated with a partially hydrolysed condensate of a tetraalkoxysilane. The silicone rubber composition, containing the calcium carbonate filler treated with a hydrolysed condensate of tetraalkoxysilanes, provides a low evolution of a hydrogen gas during its storage, and has superior fluidity and electrical characteristics and is said to prevent foaming during the storage of the composition. There is no teaching in this document that the composition can be used as an adhesive for silicone rubber, and the adhesion of this composition to silicone rubber is still inadequate.
As a result of research aimed at overcoming the aforementioned shortcomings, the inventors have developed the present invention based on the fact that adequate adhesion to silicone rubber can be obtained by utilising an addition reaction curable silicone composition containing calcium carbonate powder with a prescribed BET specific surface area.
Specifically, an object of the present invention is to provide an adhesive for silicone rubber that has good adhesion to silicone rubber materials.
DETAILED DESCRIPTION OF THE INVENTION
In accordance with the present invention there is provided a silicone rubber adhesive composition comprising the following components:
A. 100 parts by weight of an organopolysiloxane having an average of two or more alkenyl groups per molecule;
B. an organopolysiloxane having an average of two or more silicon bonded hydrogen atoms in each molecule, in an amount such that the molar ratio of silicon bonded hydrogen atoms in component B to alkenyl groups in component A is from 0.01 to 20, i.e. from 1:100 to 20:1;
C. From 5 to 200 parts by weight of a calcium carbonate powder selected from the group of untreated calcium carbonate, calcium carbonate treated with an organic acid and calcium carbonate treated with an ester of an organic acid, said calcium carbonate having a BET specific surface area of from 5 to 50 m
2
/g; and
D. a platinum-based catalyst, in an amount sufficient to effect curing of the composition.
The organopolysiloxane of component A is the principal ingredient of the adhesive. This component is characterized by having an average of two or more alkenyl groups per molecule. Examples of such alkenyl groups include vinyl, allyl, butenyl, pentenyl, hexenyl, and heptenyl groups, of which the vinyl group is preferred. Examples of organic groups bonded to silicon atoms other than the alkenyl groups in component A include methyl, ethyl, propyl, butyl, pentyl, hexyl, and other alkyl groups; phenyl, tolyl, xylyl, and other aryl groups; and 3-chloropropyl, 3,3,3-trifluoropropyl, and other alkyl halide groups, of which groups the methyl group is preferred. Component A may have a molecular structure that is linear, partially branched linear, branched, reticulated, or dendritic. The viscosity of component A at 25° C., is preferably from 100 to 1,000,000 mPa·s, and most preferably from 100 to 500,000 mPa·s.
Examples of organopolysiloxanes which may be utilised as component A include polydimethylsiloxanes in which both ends of the molecular chain are blocked by dimethylvinylsiloxy terminal groups; dimethylsiloxane/methylvinylsiloxane copolymers in which both ends of the molecular chain are blocked by dimethylvinylsiloxy terminal groups; dimethylsiloxane/methylvinylsiloxane copolymers in which both ends of the molecular chain are blocked by trimethylsiloxy terminal groups; organopolysiloxanes comprising siloxane units expressed by the formula (CH
3
)
3
SiO
1/2
, siloxane units expressed by the formula (CH
3
)
2
(CH
2
═CH)SiO
1/2
, and siloxane units expressed by the formula Sio
4/2
; organopolysiloxanes obtained by methods in which some or all of the methyl groups of these organopolysiloxanes are substituted by alkyl groups such as ethyl, propyl, and the like, aryl groups, such as phenyl, tolyl, and the like, or alkyl halide groups such as 3,3,3-trifluoropropyl or the like; organopolysiloxanes obtained by methods in which some or all of the vinyl groups of these organopolysiloxanes are substituted by allyl, propenyl, or other alkenyl groups; and mixtures of two or more of these organopolysiloxanes.
Component B is an organopolysiloxane which functions as the cross-linking agent of the adhesive of the present invention. Component B is characterized by having an average of two or more silicon bonded hydrogen atoms (i.e. Si—H bonds) per molecule. The silicon bonded hydrogen atoms may be anywhere on the organopolysiloxane that forms component B, for example they may be on silicon atoms forming part of a terminal group at the end of the organopolysiloxane chain or on silicon atoms in non-terminal groups such as silicon atoms in the backbone of the organopolysiloxane polymer chain or, when present, in side chains of the organopolysiloxane polymer. The organic groups bonded to the silicon atoms in component B may include methyl, ethyl, propyl, butyl, pentyl, hexyl, and other alkyl groups; phenyl, tolyl, xylyl, and other aryl groups; and 3-chloropropyl, 3,3,3-trifluoropropyl, and other alkyl halide groups, of which the methyl group is preferred. Component B may have a linear, partially branched linear, branched, reticulated, or dendritic molecular structure. The viscosity of component B at 25° C., is preferably from 1 to 1,000,000 mPa·s, but most preferably from 1 to 10,000 mPa·s.
Examples of organopolysiloxanes which may be utilised as Component B include polydimethylsiloxanes in which both ends of the molecular chain are blocked by dimethyl hydrogen siloxy terminal groups; polymethyl hydrogen siloxanes in which both ends of the molecular chain are blocked by trimethylsiloxy terminal groups; dimethylsiloxane/methyl hydrogen siloxane copolymers in which both ends of the molecular chain are blocked by trimethylsiloxy terminal groups; cyclic polymethyl hydrogen siloxanes; organopolysiloxanes comprising siloxane units expressed by the formula (CH
3
)
2
HSiO
1/2
and siloxane units expressed by the formula SiO
4/2
Component B may also be an organopolysiloxane as described above in which some or all of the methyl groups have been replaced by alternative
Nishiumi Wataru
Shinmi Hideo
Takuman Osamu
Dow Corning Toray Silicones, Ltd.
McKellar Robert L.
McKellar Stevens, PLLC
Moore Margaret G.
Zimmer Marc S
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