Dow Corning Corporation

Dow Corning Europe Sa

Edouard Joseph

Klaus Kunz

Patrick Vandereecken

Giuseppina Conti

Robert Bonny

Ernst Gerlach

Dieter Zaulig

A hot melt sealant/adhesive composition is provided which comprises the following components&#x2014;Component A. a siloxane polymer composition comprising a) An organopolysiloxane which may comprise not less than two groups selected from i) silicon bonded alkenyl groups or ii) silicon-bonded hydroxyl groups and/or silicon bonded hydrolysable groups b) one or more fillers; and a cure system comprising c) a suitable catalyst and where required d) a suitable cross-linker adapted to react with component (a), catalysed with component (c); and either or both of components B. and C. wherein: &#x2014;B. is one or more hot melt resins; and C. is one or more waxes having a melt temperature of between 40 and 200&#xb0; C.; and/or an organic resin having a viscosity average molecular weight of from 200 to 6000 and a softening point of from 0&#xb0; C. and 150&#xb0; C.; wherein the total amount of components B and/or C in the composition is from 2 to 60% by weight of the whole composition.

Organosiloxane compositions

A polymer composition comprises a polymer matrix and a siloxane-containing additive which is substantially incompatible with the polymer matrix, wherein the siloxane of the additive has a hydroxy, alkoxy or epoxy functionality, and a functionality which is capable of bonding with a silicone elastomer-forming composition which is curable by a hydrosilylation reaction. The polymer matrix preferably comprises polyphenylenesulphide, and the additive preferably comprises hydroxy-terminated methylvinyl siloxane. The composition is capable of forming plastics articles to which cured silicone elastomers can adhere.

Polymer composition

Siloxane-based elastomer-forming compositions comprise a first a,w-dihydroxyl polydiorganosiloxane, a second a,w-dihydroxyl polydiorganosiloxane, a third a,w-dihydroxyl polydiorganosiloxane, an organosilicon compound having at least three silicon-bonded substituents selected from the group consisting of hydrogen and alkoxy groups, and a condensation catalyst. The number average molecular weight ratio of the first a,w-dihydroxyl polydiorganosiloxane to the second a,w-dihydroxyl polydiorganosiloxane is in the range of 20 to 80 and the number average molecular weight ratio of second a,w-dihydroxyl polydiorganosiloxane to the third a,w-dihydroxyl polydiorganosiloxane is in the range of 1 to 6. The molar ratio of the first a,w-dihydroxyl polydiorganosiloxane to the second a,w-dihydroxyl polydiorganosiloxane is in the range of 0.01 to 0.15 and the molar ratio of the second a,w-dihydroxyl polydiorganosiloxane to the third a,w-dihydroxyl polydiorganosiloxane is in the range of 0.2 to 2. These compositions are substantially solvent-free and result in elasomers having improved strength without fillers.

Elastomer-forming compositions

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Hofheim, Germany

Edouard Joseph