Method for coating a textile medium

A process for coating a silicone composition (A), which is a precursor of an elastomer and is polyaddition-crosslinkable, onto a textile medium, said process comprising the following steps a), b) and c):

• a) preparing a silicone composition (A) which is a precursor of an elastomer and is polyaddition-crosslinkable, comprising:
• at least one linear or branched polyorganosiloxane (B) carrying alkenyl groups and comprising:
• 1) terminal siloxyl units of type M=(X)s(R)tSiO1/2 in which the radicals R, which are identical or different, correspond to a C1-C6 linear or branched alkyl group, optionally substituted, or a substituted or unsubstituted aryl group, and the radicals X correspond to alkenyl groups having 2 to 6 carbon atoms, with s=0 or 1, t=2 or 3 and s+t=3;
• and
• 2) siloxyl units, which are identical or different, of type D=(X)u(R1)vSiO2/2 in which the radicals R1 meet the same definition as for R, the radicals X correspond to alkenyl groups having 2 to 6 carbon atoms, with u=0 or 1, v=1 or 2 and u+v=2,
• with the condition that the polyorganosiloxane (B) comprises at least two radicals X per molecule;
• at least one linear or branched polyorganosiloxane (C) carrying one alkenyl group per molecule and comprising:
• 1) terminal siloxyl units, which are identical or different, of type M=(X)w(R2)xSiO1/2 in which the radicals X correspond to alkenyl groups having 2 to 6 carbon atoms, and the radicals R2 meet the same definition as for R, with w=0 or 1, x=2 or 3 and w+x=3;
• and
• 2) siloxyl units D=(X)y(R3)zSiO2/2 in which the radicals X correspond to alkenyl groups having 2 to 6 carbon atoms, and the radicals R3 meet the same definition as for R, with y=0 or 1, z=1 or 2 and y+z=2,
• with the condition whereby the polyorganosiloxane (C) comprises just one radical X per molecule;
• at least two hydrogenopolyorganosiloxanes (D), one (D-1) having a chain extender role and the other (D-2) having a crosslinking role:
• said chain extender hydrogenopolyorganosiloxane (D-1) comprising:
• 1) terminal siloxyl units of type M=(R4)2(H)SiO1/2 in which the radicals R4 meet the same definition as for R and
• 2) siloxyl units, which are identical or different, of type D=(R5)2SiO2/2 in which the radicals R5 meet the same definition as for R,
• with the condition that the chain extender hydrogenopolyorganosiloxane (D-1) comprises two SiH functional groups per molecule;
• said crosslinking hydrogenopolyorganosiloxane (D-2) comprising:
• 1) terminal siloxyl units of type M=(R6)2(H)SiO1/2 in which the radicals R6 meet the same definition as for R and
• 2) siloxyl units, which are identical or different, of type D=(R7)p(H)qSiO2/2 in which the radicals R7 meet the same definition as for R, with p=1 or 2, q=0 or 1 and p+q=2,
• with the condition whereby that the crosslinking hydrogenopolyorganosiloxane (D-2) comprises at least three SiH functional groups per molecule;
• at least one mineral filler (E);
• catalytically effective amount of at least one hydrosilylation catalyst (F);
• at least one crosslinking inhibitor (G);
• optionally at least one unreactive polyorganosiloxane (H) comprising:
• 1) terminal siloxyl units of type M=(R8)3SiO1/2 in which the radicals R8 meet the same definition as for R and
• 2) siloxyl units, which are identical or different, of type D=(R9)2SiO2/2 in which the radicals R9 meet the same definition as for R, and
• optionally a formulation additive (I),
• with the additional condition that the amounts of the polyorganosiloxanes (B), (C) and (D) are chosen so that the molar ratio r2 of the hydrogen atoms linked to the silicone of the crosslinking hydrogenopolyorganosiloxanes (D-2) for the alkenyl radicals linked to the silicon of the polyorganosiloxanes (B) and (C) is defined as follows:
• 0.10≦r2≦0.40,
• b) next, said silicone composition (A) is deposited continuously or discontinuously on said textile medium;
• and
• c) crosslinking said silicone composition (A) by heating and/or by infrared radiation.