Abstract: Deaggregated highly disperse silicic acid, in which the average particle size is less than 100 nm, preferably less than 50 nm, is prepared by extremely high mechanical stress. The deaggregated silicic acid is employed as a filler in silicone rubber mixtures.

Abstract: The invention relates to a process for preparing polyorganosiloxanes which comprise substantially no cyclic components and have uniform molecular weight distribution by reacting organosilicon compounds which have no condensable groups in the presence of a catalyst which exclusively promotes equilibration and suppresses formation of cyclic components. The resulting polyorganosiloxanes have a linear or branched structure. They can either be used immediately, for example in silicone rubbers and silicone greases, as components in release agents, in impregnating agents, in antifoams, etc., or are starting compounds for preparing organofunctionally modified polysiloxanes which are obtained by hydrosilylation of the polyorganosiloxanes with hydrocarbons and/or organic polymers.

Abstract: The invention relates to a catalyst for preparing organosiloxanes and polyorganosiloxanes which are obtained primarily by polycondensation processes. The catalyst of the invention is a reaction product of phosphonitrilic chloride with a compound of the general formula ?R.sub.3 SiO(R.sub.2 SiO).sub.m !.sub.3 P.dbd.O (I), where R are, independently of one another, identical or different, unsaturated and/or saturated monovalent hydrocarbon radicals having from 1 to 6 carbon atoms or hydrogen, with the proviso that only one hydrogen atom is bound to each silicon atom and m has a value between 0 and 1000. Volatile chlorine-containing silicon compounds formed during the reaction can, if required, be completely or partially removed.

Abstract: Liquid polysiloxanes are used in defoamant preparations, as diffusion-resistant plasticizer oils, separation agents, or impregnation agents. The liquid polysiloxanes are obtained by reacting:(1) 100 parts by weight of the hydrolysis product of dimethyldichlorosilane having a viscosity of less than 200 mm.sup.2 /sec at 25.degree. C.;(2) 1-100 parts by weight of a polydiorganosiloxane having a viscosity of less than 200 mm.sup.2 /sec at 25.degree. C., of formula (I)R.sup.3.sub.c SiO.sub.(4-c)/2, (I)where each R.sup.3 is independently a substituted or unsubstituted hydrocarbon group with 1-30 carbon atoms, and c has mean value 1.9-3.0; and(3) 0.1-20 parts by weight of one or more compounds (a)-(d),where (a) is a silicon compound of formula (II)R.sup.4.sub.d SiX.sub.(4-d), (II)where R.sup.

Abstract: A process for preparing polyorganosiloxanes having a viscosity ranging from 0.2 to 10,000 Pas (at 20.degree. C.) by reaction of low molecular polyorganosiloxanols with each other or with oligomeric siloxanes in the presence of a catalyst system in a thin layer evaporator is disclosed. These products are silicone oils and silicone rubber polymers or starting materials for further modifications. The process is carried out at temperatures ranging from 80.degree. to 200.degree. C. and pressures ranging from 1 to 1000 mbar (abs.). The advantages include prevention of recycling through milder reaction conditions and reduction in the accumulation of intermediate fractions during product conversions.