Dow Corning Corporation

Burt Michael Wrolson

Ronald Paul Gee

Brett Lee Zimmerman

Daniel J Halloran

Eric Jude Joffre

Randal Myron Hill

Vicky Sue Cobb

Virginia Kay O'Neil

James Anderson Beck

Cassie Emelia Cuthbert

A batch steam distillation process removes volatile siloxane oligomers from an emulsion containing siloxane polymers and volatile siloxane oligomers prepared by emulsion polymerization of volatile siloxane oligomers. In one embodiment, emulsions stripped of volatile siloxane oligomers are re-catalyzed to initiate condensation polymerization. In another embodiment, clear emulsions stripped of volatile siloxane oligomers are provided even though an antifoam is used in the stripping process.

Method of making silicone emulsions having low residual volatile siloxane oligomer content

Emulsions and latexes containing polymer particles with a diameter greater than 0.02 micron are prepared by (i) forming a microemulsion containing particles of oligomers with a diameter less than 0.02 micron by combining water, a surfactant, a hydride functional organosilicon oligomer or a mixture of such oligomers, and an alkenyl functional organosilicon oligomer or a mixture of such oligomers; (ii) adding a catalyst to the microemulsion; (iii) initiating polymerization of the oligomers; and (iv) continuing polymerization until an emulsion or latex is formed containing polymer particles with a diameter greater than 0.02 micron.

Polymerization of silicone microemulsions

Emulsions and microemulsions containing particles of siloxane polymers are prepared by an emulsion polymerization process involving (i) the formation of a mixture by combining a siloxane oligomer, an ionic surfactant, no nonionic surfactant, and water; (ii) agitating the mixture without using high shearing forces (homogenization) to form droplets of oligomer prior to polymerization that have an average diameter of greater than 10 micron/10,000 nanometer; (iii) adding a siloxane polymerization catalyst to the oligomer mixture; (iv) agitating the mixture without using high shearing forces; (v) polymerizing the oligomer to form new particles of polymer; and (vi) continuing step (v) until the polymer has increased in viscosity or molecular weight.

Anionic and cationic silicone emulsions

Dialkyl sulfonic acid catalysts such as dialkyl benzene sulfonic acids, dialkyl naphthalene sulfonic acids, salts of dialkyl benzene sulfonic acids, and salts of dialkyl naphthalene sulfonic acids, are used to prepare emulsions containing particles of organopolysiloxanes having an average particle diameter in the emulsion of at least one micron (&mgr;m) A silanol endblocked siloxane is used as an oligomer and has the structure

Emulsion containing silicone particles of large size

The viscosity of a solvent is modified by thickening the solvent with a silicone latex. A silicone latex having a plurality of crosslinked polysiloxane particles is first prepared by mixing the siloxane polymer, a surfactant, and water; emulsifying the mixture to a gel phase; diluting the emulsion with water; adding a cure package (i.e., a catalyst, a crosslinker, or both, or a self catalytic crosslinker); and then without removing the water from the latex and after the particles of siloxane polymer in the latex have been cured, mixing the latex and solvent to thicken the solvent, forming viscous liquids, gels, and pastes. Water in the latex thickened solvent composition can be stabilized by adding a silicone polyether during mixing of the latex and the solvent. These stabilized latex thickened solvent compositions have beneficial properties such as clarity, shelf stability, and ease of preparation; and therefore have wide areas of application, especially as additives in antiperspirants, deodorants, and other personal care applications.

Silicone polyether stabilized silicone latex solvent thickening

Described is a method of preparing microemulsions of organopolysiloxanes, by copolymerizing a cyclic siloxane and a polyfunctional silane, in an aqueous medium containing a nonionic surfactant, an anionic or cationic surfactant, and a catalyst, until the desired increase in molecular weight is obtained. The invention resides in controlling the gel content of the organopolysiloxanes in the microemulsion by control of the concentration of silane and concentration of silanol in the resulting organopolysiloxane, such that a functionality ratio .phi. results in formation of a gel-free polymer molecular weight distribution of finite organopolysiloxane species in the microemulsion.

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Midland, MI, United States of America

Burt Michael Wrolson