Method for the preparation of organopolysiloxane free from acid catalyst residue

A method for the preparation of an organopolysiloxane free from residue of acid catalyst, which method comprises the successive steps of:

• (a) subjecting a mixture of organosiloxane oligomers to a siloxane rearrangement reaction in the presence of sulfuric acid or fuming sulfuric acid as a catalyst to effect polymerization of the organosiloxanes to equilibrium to give an organopolysiloxane containing residue of the acid;
• (b) admixing and agitating the acid residue-containing organopolysiloxane with water to affect hydrolysis of the acid residue bonded to the organopolysiloxane molecules;
• (c) subjecting the water-admixed organopolysiloxane to phase separation into an aqueous phase and a phase of the organopolysiloxane to discard the aqueous phase;
• and
• (d) washing the organopolysiloxane freed from the aqueous phase with water;
• wherein the amount of water admixed in step (b) is in the range from 30% to 100% by weight based on the amount of acid catalyst used in step (a).