Shin-etsu Chemical Co., Ltd.

Takeshi Mihama

Koji Futatsumori

Yasuaki Hara

Hisashi Aoki

Kiyohiro Kondow

Toshio Oba

Nobuyuki Hasebe

Fine spherical particles of cured silicone elastomer can be prepared by spray-drying an aqueous emulsion of a curable organopolysiloxane composition having a particle diameter not exceeding 20 .mu.m. The organopolysiloxane composition comprises preferably an organopolysiloxane having silicon-bonded vinyl groups, an organohydrogenpolysiloxane having silicon-bonded hydrogen atoms and a platinum catalyst so that curing of the composition may take place in the emulsion before spray-drying or in the course of spray-drying by the addition reaction between the silicon-bonded vinyl groups and the silicon-bonded hydrogen atoms.

Method for the preparation of fine spherical particles of silicone

So-called addition-type curable organopolysiloxane compositions curable by the hydrosilation reaction between vinyl groups of a dimethylpolysiloxane and hydrogen atoms directly bonded to the silicon atoms in a methylhydrogenpolysiloxane in the presence of a platinum catalyst can be imparted with a greatly increased pot life to have improved workability when the composition is admixed with a halogen- or alkoxy-substituted olefinic organic compound such as allyl halides, 1,3- and 2,3-dihalogenopropenes, 2-alkyl-3-halogenopropenes, 1,3- and 1,4-dihalogenobutenes-2 and alkyl allyl ethers as a moderator of the crosslinking reaction without any adverse effect on the curability of the composition.

Curable organopolysiloxane composition

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Takeshi Mihama