Process for producing polydiorganosiloxane based graft copolymers

A process for producing a polydiorganosiloxane-based graft copolymer with controlled particle size distributions, which comprises;

• (a) homogenizing an admixture to form an emulsion of polydiorganosiloxane particles, said admixture comprising:
• (i) polydiorganosiloxane of the formula:
• HO(R.sub.2 SiO).sub.x H
• wherein each R is a radical selected from the group consisting of alkyl and alkene radicals, and wherein the average x is between 10 and 100,
• (ii) a vinyl functional organosiloxane grafting agent,
• (iii) an emulsifying agent,
• (iv) a crosslinking agent, and
• (v) water,
• (b) maintaining the catalyzed emulsion at a temperature of from 1.degree. C. to 30.degree. C. at a pH of less than 5 until the desired molecular weight and level of crosslinking of the polydiorganosiloxane is obtained to form vinyl functional silicone rubber particles;
• and
• (c) graft polymerizing a vinyl monomer composition onto the resulting silicone rubber particles, whereby the polysiloxane-based graft copolymer has particle sizes ranging from 350 Angstroms to 9000 Angstroms.

A process for producing a polydiorganosiloxane-based graft copolymer with controlled particle size distributions, which comprises:

• (a) mixing at least two polydiorganosiloxane fluids each of the formula:
• HO(R.sub.2 SiO).sub.x H
• wherein each R is a radical selected from one group consisting of alkyl and alkene radicals and wherein at least two of said fluids have viscosity differences of at least 0.02 Pa.S at 25.degree. C. to form an admixture having a desired viscosity;
• (b) homogenizing said admixture to form emulsions;
• (c) polymerizing said polydiorganosiloxanes in the presence of catalyst, crosslinking agents and grafting agent to form vinyl functional silicone rubber particles, and;
• (d) graft polymerizing a vinyl monomer composition onto the resulting silicone particle, whereby the polysiloxane-based graft copolymer has particle size ranging from 350 Angstroms to 9000 Angstroms.

A process for producing a polyorganosiloxane based graft polymer with controlled particle size distributions, said process comprising:

• (a) preparing an aqueous emulsion by homogenizing a dihydroxy functional polydiorganosiloxane fluid;
• (b) polymerizing the polydiorganosiloxane in the presence of a vinyl functional grafting agent and a crosslinking agent to form silicone rubber particles having vinyl grafting sites;
• and
• (c) graft-polymerizing a vinyl monomer composition onto the resultant silicone rubber particles to form a polyorganosiloxane based graft polymer, whereby the polysiloxane-based graft copolymer has particle size ranging from 350 Angstroms to 9000 Angstroms.

A process for making a graft copolymer having controlled particle size distributions comprising:

• (a) preparing an emulsion by homogenizing dihydroxy functional polydiorganosiloxane polymers;
• (b) polymerizing and crosslinking the polydiorganosiloxane polymers in the presence of a vinyl functional grafting agent to form vinyl functional rubber particles;
• and
• (c) graft polymerizing at least one vinyl monomer on to the rubber particles to form a graft copolymer, whereby the polysiloxane-based graft copolymer has particle size ranging from 350 Angstroms to 9000 Angstroms.