Dow Corning Corporation

Steven Patrick Mullan

Chi-long Lee

David Joseph Romenesko

Carl J Bilgrien

Herschel Henry Reese

A free-flowing silicone rubber powder, having an average particle size of 1 to 1000 microns and prepared by mixing a polydiorganosiloxane with a silica filler, is uniformly dispersed in a poly(phenylene ether) resin using conventional equipment, such as a single screw or, preferably, a twin screw extruder. When employed at relatively low concentrations, such as about 0.2 to 3 parts by weight of powder per 100 parts by weight of resin, a significant improvement in the processability is obtained, while modification at higher levels, such as 5 to 20 parts by weight of powder per 100 parts by weight of the resin results in a resin composition having greatly augmented impact resistance.

Poly(phenylene ether) resin modified with silicone rubber powder

Storage stable and gel-free organosiloxane compositions in the form of flowable powders are prepared by blending a high consistency polydiorganosiloxane into a quantity of fluidized reinforcing filler that is heated to a temperature of from 100.degree. to 200.degree. C. prior to or immediately following introduction of the polydiorganosiloxane. When silica is the reinforcing filler, the filler is typically treated with an anti-creping agent either prior to or during this blending process. The resultant mixture is heated while being subjected to shearing forces that reduce its average particle size to achieve a flowable powder.

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Sanford, MI, United States of America

Steven Patrick Mullan