Patent ID: 6867242
Filing Date: 2005-03-15
Classification: C08K,C09K

Abstract:
1. A process for carrying out impregnation and/or for preparing a coating which gives release and is leaktight employed at the engine block/cylinder head interface of engines and applied to sheet gaskets, comprising: 1 employing a silicone composition comprising: A 100 parts by weight of at least one polyorganosiloxane (POS) crosslinkable by the cationic and/or radical route and via crosslinking functional groups (CFGs), these CFGs being identical to or different from one another and being selected from the group consisting of at least one functional unit of heterocyclic nature having one or more electron-donating atoms, at least one ethylenically unsaturated functional unit that is substituted by at least one electron-donating atom which enhances the basicity of the π system, and mixtures thereof; B from 0.01 to 10 parts by weight of at least one initiator salt (PI) which is a borate of an onium of an element from groups 15 to 17 of the Periodic Classification or of an organometallic complex of an element from groups 4 to 10 of the Periodic Classification,  a cationic entity of said borate being selected from the group consisting of: (1) onium cations of formula (I):  in which formula: (2) the oxoisothiochromanium cations having the formula:  where the R (3) sulfonium cations where the cationic entity comprises at least one of: with the proviso that: in which Ar 1 and Ar 2 have the meanings given above with respect to the formula (III.1), including the possibility of connecting directly between them only one of the Ar 1 radicals to A 2 according to the way indicated above with respect to the definition of the additional condition in force when t=1 in the formula (II) involving the Y′ residue; (4) organometallic salts cations of formula (IV):  in which formula: C 1 to 50 parts by weight of at least one reactive diluent selected from the group consisting of a nonorganosilicon organic compound, and an organosilicon comprising, in its structure, at least one CFG as defined above and at least one secondary functional group (SFG) other than a CFG but capable of reacting chemically with a CFG; D 0 to 10 parts by weight of at least one pigment; E 0 to 100 parts by weight of a filler of inorganic nature; F 0 to 10 parts by weight of at least one photosensitizer; G 0 to 10 H 0 to 5 parts by weight of an adhesion promoter; 2 applying this composition to a support, and 3 crosslinking the applied composition by photochemical and/or thermal activation and/or under an electron beam.