POLYSILOXANES

摘要

1482004 Polyolefin-filled polysiloxanes GENERAL ELECTRIC CO 8 Oct 1974 [26 Dec 1973] 43587/74 Headings C3P and C3T A polyolefin-filled vinylorganopolysiloxane comprises a continuous phase of ungrafted vinylorganopolysiloxane of 10 to 107 cp./25‹ C. having dispersed therein a discontinuous phase of a finely divided solid ungrafted polymer obtained by polymerizing an unsaturated monomer or mixture of monomers in the presence of the polysiloxane. The polymerization may be carried out in the presence of a free radical catalyst at a temperature sufficient to effect polymerization but insufficient to cause grafting on to the siloxane, e.g. 35-135‹ C. The composition may be used in conjunction with a hydrogen organopolysiloxane and a Pt catalyst to give an RTV composition; this may be stored as a 2-part pack, one part containing the filled vinyl siloxane, the Pt catalyst and any further, conventional, additives, the second the hydrogen siloxane. In Examples 1-3 vinyl acetate or styrene is polymerized at c. 90‹ C. in the presence of azobisisobutyronitrile or t-butyl peroctoate in a vinyl-terminated polydimethylsiloxane of 300 or 3500 cP./25‹ C. to give dispersions of which 40 wt. per cent is particulate polymer and the reported viscosities range from 1450 cP. to 195,000 cP. In Examples 4-7 these dispersions are mixed with 1À3-2À5 wt. per cent of a copolymer of Me 2 HSiO 0À5 and SiO 2 units and a catalyst of Pt complexed with Me 2 ViSiOSiMe 2 Vi or [MeViSiO] 4 to give rubbers.