Abstract: A technique and apparatus are disclosed for injection molding highly filled conductive resin compositions. These compositions include one or more of unsaturated polyester and vinyl ester resin; a copolymer having a terminal ethylene group; and at least about 50 weight percent of an inorganic particulate conductive filler, an initiator, and a rheological modifier to prevent phase separation between said resin and said conductive filler during molding. The method of the present invention allows these compositions to be molded into highly intricate and thin electrically and thermally conductive specimens without significant post process machining. The method involves the use of an injection molding apparatus that has a hopper with an auger having a vertical component in its positioning to feed into the feed throat of an injection molding machine which has a phenolic screw that has been modified to have a constant inner diameter and a constant flight depth.

Abstract: A technique and apparatus are disclosed for injection molding highly filled conductive resin compositions. These compositions include one or more of unsaturated polyester and vinyl ester resin; a copolymer having a terminal ethylene group; and at least about 50 weight percent of an inorganic particulate conductive filler, an initiator, and a rheological modifier to prevent phase separation between said resin and said conductive filler during molding. The method of the present invention allows these compositions to be molded into highly intricate and thin electrically and thermally conductive specimens without significant post process machining. The method involves the use of an injection molding apparatus that has a hopper with an auger having a vertical component in its positioning to feed into the feed throat of an injection molding machine which has a phenolic screw that has been modified to have a constant inner diameter and a constant flight depth.