Patent ID: 8410239

Claim:
An organopolysiloxane composition crosslinkable into a silicone foam having a density of less than 0.20 g/cm 3 , and a tensile strength of greater than 0.10 MPa; said composition consisting essentially of: (A) at least one polyorganosiloxane (A) having, per molecule, at least two C 2 -C 6 alkenyl radicals bonded to silicon and having a viscosity ranging from 10 to 300,000 mPa·s and said polyorganosiloxane (A) comprises end vinylsiloxy units, (B) at least one polyorganosiloxane (B) having, per molecule, at least two hydrogen atoms bonded to silicon and having a viscosity ranging from 1 to 5,000 mPa·s, (C) a catalytically effective amount of at least one platinum group metal catalyst (C), (D) at least one compound (D) selected from the group consisting of n-propanol, n-butanol, n-hexanol and n-octanol, (E) optionally, at least one diorganopolysiloxane oil (E) blocked at each end of its chain by a triorganosiloxy structural unit, the organic radicals of which bonded to silicon atoms are selected from among alkyl radicals having from 1 to 8 carbon atoms, 3,3,3-trifluoropropyl radicals, cycloalkyl radicals, and aryl radicals, (F) optionally, at least one inorganic and/or metal filler (F), (G) optionally, at least one additive (G), and (H) at least one polyorganosiloxane resin (H), with the provisio that: (1) said resin (H) is present in a proportion of at least 10% by weight, with respect to the total weight of the polyorganosiloxane (A) and of the polyorganosiloxane resin (H) (=ratio by weight (H)/[(A)+(H)]×100); and (2) said resin (H) comprises at least two different siloxyl structural units selected from among those of the following formulae (I) and (II): W a Z b SiO (4−(a+b))/2 (I) in which: the W symbols, which may be identical or different, are each a C 2 -C 6 alkenyl radical; the Z symbols, which may be identical or different, are each a nonhydrolyzable monovalent, optionally halogenated hydrocarbon radical that does not adversely affect the activity of the catalyst; a is 1 or 2, b is 0, 1 or 2 and the sum a+b is equal to 1, 2 or 3, and Z c SiO (4−c)/2 (II) in which Z is as defined above and c is equal to 0, 1, 2 or 3, and at least one of the structural units (I) or (II) is a T or Q unit, and with the further proviso that the viscosity of said composition is less than 15,000 mPa s, said composition being devoid of: (i) water, as porogenic agent generating, in the presence of a polysiloxane comprising hydride functional groups, gaseous hydrogen, (ii) polyorganosiloxane comprising hydroxyl groups, and (iii) cyclic polydiorganosiloxane comprising ≡SiH functional groups.