Abstract: A silicone self-adhesive composition is comprised of (A) high viscosity organopolysiloxane raw rubber, (B) MQ resin, (C) organohydrogenpolysiloxane, (D) platinum catalyst, and (E) high vinyl content organopolysiloxane. It cures at relatively low temperature into an adhesive layer which has good adhesive properties and heat resistance, finding use as heat resistant adhesive tapes and labels.

Abstract: A silicone self-adhesive comprising an organopolysiloxane obtained by partial condensation of from 40 to 80 parts by weight of a diorganopolysiloxane containing at least an alkenyl group and a aryl group and correspondingly from 60 to 20 parts by weight of a copolymer which consists essentially of SiO.sub.2 units and R'.sub.3 SiO.sub.0.5 units, in which each R' represents a monovalent hydrocarbon group having not larger than 3 carbon atoms, at a mixing ratio by mole of from 1:0.3 to 1:1.5 and which has at least one hydroxyl group directly bonded to a silicon atom in the molecule, and an organohydrogenpolysiloxane used in an amount sufficient to give from 1 to 30 Si-H bonds per one vinyl group of the above ingredient. A catalytically effective amount of a platinum catalyst is added to the above self-adhesive. An self-adhesive tape or sheet using the above self-adhesive is also provided.

Abstract: The invention proposes use of ammonia water in place of a conventional caustic alkali or amine compound as a catalyst in the siloxane rearrangement reaction for the preparation of a silicone-based pressure-sensitive adhesive between a poly(diorganosiloxane) having a linear molecular structure and another organopolysiloxane composed mainly of the monofunctional organosiloxane units and tetrafunctional siloxane units. The ammonia water after completion of the reaction can be easily and completely removed by distillation so that the resultant adhesive product is free from any alkaline residue of the catalyst to be imparted with greatly improved stability against viscosity changes and excellent electrical properties along with high reproducibility of the product quality.

Abstract: The organopolysiloxane compositions comprising a dimethylpolysiloxane, an organohydrogenpolysiloxane, a silica filler, zinc carbonate, ceric oxide, and a platinum compound. They are useful for producing electrically insulating materials and fire-resistant materials with excellent heat stability and flame retardancy.