Abstract: Room temperature vulcanizable organopolysiloxane compositions comprising derivatives of silacycloalkanes are described and they unexpectedly display a reduction in viscosity prior to curing, a reduction in modulus after curing and favorable cure rates.

Abstract: Solventless and high solids-containing silicone pressure sensitive adhesive compositions having high peel adhesion and high tack are provided, comprising (A) a toluene-soluble resinous copolymer containing R.sub.3 SiO.sub.1/2 units and SiO.sub.4/2 units; (B) a vinyl-terminated polydiorganosiloxane; (C) a hydrogen-terminated polydiorganosiloxane; (D) a hydrosilation catalyst; and (E) from 0 to about 10 percent by weight of an organic solvent; provided that the combined viscosity of (B) and (C)is from about 10 to about 500 centipoises at 25.degree. C., the combined crosslink densities of (B) and (C) is from about 0.3 to about 5.0%, preferably 0.3 to about 2.0%, and the molar ratio of silicon-bonded hydrogen groups in (C) to silicon-bonded alkenyl groups in (B) is in the range of from about 0.8:1 to about 1.5:1 and preferably about 1:1.

Abstract: The present invention is directed to solvent free particulated platinum group metal silicone resin catalyst resulting from the spray drying of an organic solvent mixture of a platinum group metal complex, and an alkenyl containing organosiloxane resin. Heat curable organopolysiloxane compositions containing such particulated platinum group metal silicone resin catalyst are also provided.

Abstract: A method is provided for making a heat curable organopolysiloxane composition, such as a pressure sensitive adhesive composition by blending a benzene soluble resinous copolymer in the form of a spray dried particulate, comprising triorganosiloxy units, such as trimethylsiloxy units, and SiO.sub.2 units with a fluid network mixture of an alkenyl siloxane, a silicon hydride siloxane and a hydrosilylation catalyst.

Abstract: A free flowing silicone powder having a primary particle size in the range of 0.1-200 nm and an aggregate size of 10 nm to 200 microns which is a product formed by spray drying an organic solvent dispersion of an organosiloxane hydrolyzate having triorganosiloxy units and tetrasiloxy units.

Abstract: A method for making a substantially silanol-free silicone resin powder having a primary particle size in the range of about 0.1-200 nm and an aggregate particle size of 10 nm to 200 microns is provided. An organic solvent dispersion of an organosiloxane hydrolyzate having triorganosiloxy units and tetrasiloxy units is treated with an organo nitrogen compound, such as a silazane and thereafter spray dried. The substantially silanol-free organosilicon powder has been found useful in making heat curable organopolysiloxane compositions, such as pressure sensitive adhesives.

Abstract: Silicon hydrides substituted with oxygen containing radicals such as alkoxy, can be silylformylated with alkynes and carbon monoxide in the presence of a rhodium catalyst to produce silyl alkenyl acetals. The silyl alkenyl acetals are useful as plasticizers for organosilicon copolymers.

Abstract: A moisture curable solventless organopolysiloxane composition is provided useful as an adherent construction sealant. Improved cure rate, higher elongation at break values and lower modulus RTVs are achieved by using a bis(ureido)silane as a coupler and an aminoxysiloxane as a crosslinker for a silanol-terminated polydiorganosiloxane base polymer.