Patent ID: 8859096

Claim:
A granular pumice comprising: a surface coated with a hydrophobic coating, wherein the coating comprises a mixture of a silane and a siloxane; wherein the silane is: A1) a silane of the general formula: R 3 —Si—(OR 2 ) 3 ; where: R 2 is a methyl or ethyl radical; and R 3 is: an alkyl radical having from 3 to 12 carbon atoms; or an aminoalkyl radical having from 1 to 6 carbon atoms; or a radical of the general formula H 2 N—(CH 2 ) x R 4 —(CH 2 ) y —, where: R 4 is an oxygen, sulfur, —NH—, or —NH—CH 2 —CH 2 —NH— radical; x≧2; and y≧2; or a radical of the general formula: (R 2 O) 3 Si—(CH 2 ) x —NH—(CH 2 ) x —, where R 2 and x are as defined above; where n is an integer from 1 to 5, or wherein the siloxane is: A2) a siloxanol of the general formula: where: R 5 is a methyl or phenyl radical, with at least 90% of the radicals R 5 being methyl radicals; and m=20 to 250; and wherein the mixture comprises: the silane compound as per A1); and the siloxanol compound as per A2); where a ratio of A1) to A2) is kept so that one SiOH group of the compound A2) corresponds to from >1 to 3 OR 2 groups of the compound A1); and where R 2 is an alkyl radical having from 1 to 4 carbon atoms.