GB769669A - A process of preparing organopolysiloxane compositions - Google Patents

Abstract

In making an organopolysiloxane by hydrolysing one or more silanes of the general formula RnSiX4-n, wherein each R is a monovalent hydrocarbon or halogenated hydrocarbon radical, X is a hydrolysable radical and n has a value from 1 to 2, the hydrolysis is effected in the presence of styrene in amount such that the hydrolysis product is in solution therein, and the styrene solution is thereafter separated from the aqueous phase and any hydrolysis by-products. The term styrene includes styrene, a -methylstyrene, chlorostyrene, bromostyrene, vinyltoluene, divinylbenzene and mixtures thereof, and the amount used may range from 1 to 99 per cent by weight of the finished product. Silanes specified are dimethyldichloro-, vinylphenyldiethoxy-, diphenyldiacetoxy-, octadecyltri-, chloro-, cyclohexyldichloro -, methyldichloro -, chlorophenylmethyldichloro -, trifluoromethyl - phenyltrifluoro -, bromoxenyltrichloro - and tolylmethyldichloro-silanes and phenylmethylsilazanes; and these may be used with unsubstituted silanes, e.g. silicon tetrachloride, ethyl silicate or trichlorosilane, or with R3SiX silanes. The hydrolysis may be effected by adding the silane(s) to a mixture of styrene and water, and preferably a polymerization inhibitor, e.g. tertiary butyl catechol, and carrying out the hydrolysis at temperatures below the reflux temperature of the styrene. Alternatively, the water may be added to a styrene solution of the silane(s). If desired minor amounts of other solvents, e.g. ethanol, may be added. In examples, siloxane solutions are made in the above manner from (1) methyltrichloro-, phenyltrichloro-, dimethyldichloro- and diphenyl-dichlorosilanes; (2) butyltrichlorosilane; (3) dimethyldichloro-, phenyltrichloro- and methyltrichloro-silanes; (4) dimethyldichloro,- chlorophenyltrichloro- and vinyltrichloro-silanes. The solution from (1) was added to a maleic anhydride polyester resin in amounts varying from 1 to 50 per cent by weight of polysiloxane calculated on the total composition, and cured; The solution from (2) was added to styrene monomer or a partial polymerisate thereof and then polymerized. The compositions may be incorporated in any compatible organic resin, whether synthetic or natural.