| abstract |
A method for continuous preparation of a high consistency or liquid silicone rubber base does not cause abrasive wear of the extruder screw and of the extruder cylinder or blackening of the silicone rubber base even when the latter is admixed with such fillers as an inorganic filler in the form of a diatomaceous earth powder, quartz or a similar large-grained and hard substance, or with a fumed silica, sedimentary silica, or a similar reinforcing silica filler. The method comprises continuously kneading the following components in a multiple-stage shear type single-screw extruder: (A) a freely-flowable powdered silicone rubber mixture having its main components in the form of (a) a cross-linkable polydiorganosiloxane with a viscosity exceeding 1x105 mPaxs at 25 DEG C. and (b) an inorganic filler, and (B) a high consistency silicone rubber base having its main components in the form of (a) a cross-linkable polydiorganosiloxane with a viscosity exceeding 1x105 mPaxs at 25 DEG C. and (c) a reinforcing silica filler, or a liquid silicone rubber base having its main components in the form of (d) a cross-linkable polydiorganosiloxane with a viscosity below 1x105 mPaxs at 25 DEG C. and (c) a reinforcing silica filler. |