G.B. Patent Specification 910 513 d

G.B. Patent Specification 910 513 discloses the use of phosphonitrile halides in a process for the manufacture of stabilised high viscosity organopolysiloxane oils, which comprises preparing a fluid mixture of the halides with a hydroxyl-terminated diorganopolysiloxane and a triorganosilyl end-blocked diorganopolysiloxane with a viscosity from 1 to 10000mm2/s, followed by bringing the mixture in contact with a stream of air at room temperature, until the viscosity is stabilised and thereafter bringing the mixture in contact with a stream of air at a temperature of from 100 to 200° C. until the viscosity is stabilised