GB675057A - Improvements in or relating to organopolysilane resins - Google Patents

Abstract

In making an organopolysilane resin, in which the silicon atoms are interconnected and the remaining valencies are satisfied by phenyl and methyl radicals the average number of which are from 1.2 to 2, inclusive, per silicon atom, between 20 and 70 per cent of the total phenyl and methyl radicals being phenyl radicals, an alkali metal is reacted with the chloro-silane CH3.C6H5.SiCl2 or a chloro-silane mixture having the average formula (CH3)n.(C6H5)m.SiCl4-n-m, in which the value of n+m is from 1.2 to 2 inclusive and m/n+m is from 0.2 to 0.7. The reaction may be effected either by adding the alkali metal, such as sodium, potassium, caesium, rubidium or sodium-potassium eutectic, to the chlorosilane(s) or by adding the chlorosilane(s) to a dispersion of the alkali metal in an aliphatic or aromatic hydrocarbon, e.g. toluene and xylene, and at temperatures preferably between 50 DEG and 200 DEG C. The product may be conventionally purified from residual alkali metal and the alkali salts produced by the reaction. Chlorosilanes specified are CH3SiCl3, C6H5.SiCl3, C6H5.CH3.SiCl2, (C6H6)2.SiCl2, (CH3)2.SiCl2, (C6H5)3SiCl, (C6H5)2CH3.SiCl, C6H5.(CH3)2SiCl and (CH3)3SiCl. The thermoplastic products may be used in molten state or in solvents such as petroleum-naphtha, xylene or toluene, for coating surfaces. The resin thus applied may be thermally set by heating in air or other inert gas such as nitrogen or flue gas. The resins may also be used for electrical insulation and for thermoplastic moulding compositions. Catalysts may be used to increase rate of setting or to lower the temperature required to effect the setting. Examples are given.