Process for preparing silicone rubber matrix composition

The present invention provides a process for the continuous preparation of a silicone rubber matrix composition using in situ silica treatment and twin screw extruder technology, the process comprising (a) introducing a hydrophobic treatment agent (C), a diorganopolysiloxane containing at least two alkenyl and/or alkynyl groups, and optionally water into a first static mixer, and then introducing it into a first twin screw extruder; (b) adding a reinforcing silica filler at a temperature of 20 DEG C to 80 DEG C and providing at least one vent opening to the atmosphere upstream and/or downstream of the inlet port of the reinforcing silica filler (B) to allow escape of present gases; (c) mixing in the extruder; (d) further mixing in the residence zone; (e) vacuum stripping at a temperature of at least 100 DEG C; and (f) introducing component (C) into the twin screw extruder between step (c) and step (d) and/or during step (d) to dilute and further hydrophobically treat the silica. Also provided are the resultin