Bayer Aktiengesellschaft

Gunther Maass

Hans Joachim Lucking

Hans Sattlegger

Hans-Heinrich Moretto

Manfred Beck

Bruno Degen

Karl Brandle

Manfred Schulze

Karl-Heinz Rudolph

Werner Buchner

Karl-Friedrich Thom

Joachim Maas

Klaus Seyfried

Hans-Joachim Lucking

This invention relates to a process for the preparation of organosiloxanes, in particular those containing a high proportion of low molecular weight cyclic and chain structured organosiloxanes, preferably cyclic dimethylsiloxanes, by hydrolysis of the corresponding organochlorosilanes, in which a high proportion of gaseous hydrogen chloride is formed at the same time.

Process for the preparation of organosiloxanes

The present invention relates to a process for the preparation of trioganosilyl-terminated polydiorganosiloxanes by basic polymerization of cyclic diorganopolysiloxanes and triorganosilyl-terminated siloxanes, wherein, before the polymerization, a part of the cyclic diorganosiloxane is distilled off in the presence of the polymerization catalyst at a temperature which is at least 10.degree. C. below the polymerization temperature.

Preparation of polydiorganosiloxanes having terminal triorganosilyl

In a plastic organosiloxane molding composition which in the absence of water is capable of being stored and in the presence of moisture is cross-linked to a rubber, the composition comprising a hydroxypolydiorganosiloxane, a nitrogen base and heavy metal compound as cross-linking catalyst, and a cross-linking agent, the improvement which comprises employing as the cross-linking agent a compound of the formula ##STR1## or a partial hydrolysis product thereof, wherein R is an optionally substituted alkyl, alkenyl or aryl group,

Storable crosslinkable organopolysiloxane molding compositions

In the preparation and working up of a SiOC-linked polysiloxane/polycarbonate copolymer comprising reacting an .alpha.,.omega.-dihalogenopolysiloxane with an .alpha.,.omega.-dihydroxy-oligocarbonate in the presence of a tertiary amine and a solvent, and subsequently separating off the resulting copolymer from the reaction mixture additionally containing the amine, amine hydrochloride and organic solvent, the improvement which comprises subjecting the reaction mixture to steam distillation whereby the copolymer remains behind. Advantageously, the copolymer reaction solution is added to an aqueous solution having a pH of 7 to 8 whereby the amine and hydrogen chloride also distill over. If a surface active agent is present in the aqueous solution the product will be of very fine particle size.

Working up polysiloxane/polycarbonate copolymers

In the preparation of a cyclic diphenylsiloxane of the formula ##STR1## WHEREIN N IS 3 OR 4, BY HYDROLYSIS OF A DIPHENYLDIHALOGENOSILANE, THE IMPROVEMENT WHICH COMPRISES ADDING THE DIPHENYLDIHALOGENOSILANE, IN THE PRESENCE OF AN ORGANIC, APROTIC SOLVENT TO AN AQUEOUS BASIC SOLUTION, THE BASE BEING EMPLOYED IN AN AMOUNT WHICH IS AT LEAST STOICHIOMETRICALLY EQUIVALENT TO THE HALOGEN CONTENT, WHEREBY THE CYCLIC DIPHENYLSILOXANE IS OBTAINED IN HIGH YIELD AND PURITY. The base is preferably lithium hydroxide, potassium hydroxide or sodium hydroxide and is used in the form of an at least 5 molar solution, about 2.1 to 2.5 equivalents being used per mole of diphenyldihalogenosilane.

Preparation of cyclic diphenylsiloxanes

In the preparation of cyclic and linear organosiloxanes by reacting an organohalogenosilane with a compound of the formula

Preparation of organosiloxanes

A polysiloxane composition which can be cross-linked under atmospheric conditions and which consists essentially of: A. 100 parts by weight of an .alpha.,.omega.-dihydroxymethylphenylpolysiloxane with about 7-15 mole % of diphenylsiloxy units or about 14-28 mole % of methylphenylsiloxy units, and having a viscosity of between about 1,000 and 500,000 cSt (at 20.degree. C), b. about 1 to 40 parts by weight of an uncoated reinforcing filler consisting essentially of SiO.sub.2 having a specific surface area of about 40 to 500 m.sup.2 /g by the BET method, and C. about 1 to 10 parts by weight of a cross-linking agent of the formula

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Bergisch-Gladbach, Germany

Gunther Maass