Process for producing polydiorganosiloxane based graft copolymers

A process for producing a polydiorganosiloxane based graft copolymer is provided. The process involves producing an emulsion of crosslinked polydiorganosiloxane by admixing dihydroxyfunctional polydiorganosiloxane, an emulsifying agent, and water; polymerizing the polydiorganosiloxane in the presence of an acid catalyst, a cross linking agent and a grafting agent to form silicone rubber particles having functional sites, and graft polymerizing a vinyl functional monomer onto the resulting silicone particles. The process provides several advantages in a rubber particle size control thereby resulting in better control of the properties of the resulting graft copolymer.