Method of manufacturing a (foamed) soft elastic silicone elastomer, especially for sealing purposes

摘要

The prodn. of foamed or unfoamed soft-elastic silicone elastomers (I), esp. for sealing applications, pref. for housing and cover seals, seals for cars etc., from a 2-component, addn.- crosslinked silicone system comprises mixing (A) component contg. (a1) a silicone polymer with at least 2 vinyl gps./mol., (a2) a Pt catalyst and (a3) fillers, colour pigments, adhesion improvers, antioxidants, reinforcing agents etc.; with (B) a crosslinker component contg. (b1) a hydrogen- siloxane and opt. (b2) other additives; in a 2-component mixing/metering system without external heating. At least one of the components (A, B) contains, as filler and extender, elastic microspheres (II) in the form of hollow spheres of expanded polymer (IIa) with an inorganic mineral coating (IIb). Pref. (II) consists of a polyacrylonitrile copolymer or polyvinylidene chloride copolymer with a particle size of not more than 200 (pref. 20-50) mu , coated with CaCO3. Catalyst (a2) is an organic Pt catalyst contg. 300-3000 (pref. 300-900) ppm Pt per 1000 g silicone polymer in the mixt. Pref. (b1) is a poly-hydrogensiloxane with a Si-H content of 15 mmoles/g.