Patent ID: 7084193

Claim:
A process for the preparation of a suspension of a particulate silica filler in a silicone material (SM) comprising: at least one type A polyorganosiloxane (POS) carrying alkenyl crosslinking groups Fa capable of reacting with the crosslinking groups Fb (SiH) of at least one type B POS, said POS A being taken on its own or mixed with at least one unreactive POS (E); and/or at least one type C POS carrying hydroxyl crosslinking groups Fc and/or groups OR (R=C 1 –C 20 alkyl) as precursors of the groups Fc, these crosslinking groups Fc being capable of reacting with other crosslinking groups Fc of this POS C or other POS Cs and with crosslinking groups of at least one crosslinking agent D, said POS C being taken on its own or mixed with at least one unreactive POS (E); or at least one unreactive POS (E), this suspension being usable for the production of compositions crosslinkable by polyaddition and/or polycondensation or antifoaming silicone compositions, said process comprising the steps of: a) treating and contacting all or part of the particulate filler which is a precipitated silica with at least one fraction (CA.I) of a compatibilizing agent (CA) added to a preparation medium in at least two separate fractions (CA.I) and (CA.II) which are quantitatively identical to or different from one another, water being present in a percentage weight ratio r=water/(water+silica): 60% <r<90%, b) adding all or part of the SM with the filler resulting from step a), c) optionally, drawing off at least part of the water and the by-products of the reaction of CA.I with SM, d) incorporating CA.II and any remaining SM, e) leaving the whole obtained in step d) to react, optionally under the action of heat, so that CA reacts with the silica filler, to give a product, and f) recovering the product obtained in step e).