Method for coating a tin-free silicon composition on a flexible medium

A method for coating a silicone composition X, which is a precursor of an elastomer and is crosslinkable by polycondensation reactions, onto a flexible substrate S which is made of textile, of paper, of polyvinyl chloride, of polyester, of polypropylene, of polyamide, of polyethylene, of polyurethane, of nonwoven fiberglass fabrics or of polyethylene terephthalate, the method comprising the following steps a), b), and c):

• a) preparing a silicone composition X that is crosslinkable to elastomer by polycondensation reactions, which contains no metal catalyst, and which comprises:
• a silicone base B comprising at least one polyorganosiloxane oil which is crosslinkable by polycondensation reaction so as to form a silicone elastomer, and
• a catalytically effective amount of at least one polycondensation catalyst A, which is a nonsilylated organic compound conforming to the general formula (I):
• in which
• the identical or different radicals R1 represent independently of one another a linear or branched monovalent alkyl group, a cycloalkyl group, a (cycloalkyl)alkyl group, the cyclic moiety being substituted or unsubstituted and optionally comprising at least one heteroatom or a fluoroalkyl group,
• the radical R2 represents a hydrogen atom, a linear or branched monovalent alkyl group, a cycloalkyl group, an alkyl group substituted by a cyclic moiety which is substituted or unsubstituted and optionally comprises at least one heteroatom, an aromatic group, an arylalkyl group, a fluoroalkyl group or an alkylamine or alkylguanidine group, and
• the radical R3 represents a linear or branched monovalent alkyl group, a cycloalkyl group, an alkyl group which is substituted by a cyclic moiety which is substituted or unsubstituted and optionally comprises at least one heteroatom, or an arylalkyl, fluoroalkyl, alkylamine or alkylguanidine group;
• when the radical R2 is not a hydrogen atom, the radicals R2 and R3 may can be joined to form a 3-, 4-, 5-, 6- or 7-membered aliphatic cyclic moiety optionally substituted by one or more substituents, and
• with the further condition that the radicals R1, R2, and R3 contain no silicon atom;
• b) then applying said silicone composition X continuously or discontinuously to said flexible substrate S, and
• c) crosslinking said silicone composition X in the presence of moisture provided by the ambient air or by prior addition of water, so as to form a silicone elastomer.