Apprêt de surface en vue d'une enduction par des compositions d'organo silicium

In coating surfaces (see Division B2), the surface is first coated with a liquid organosilicon primer, which is then dried, and further coated with a curable siloxane composition which is reactive with the primer, and then cured. The primer is a silane, siloxane or silcarbane-siloxane containing per Si atom an average of from 0.2 to 1 Si-bonded H and from 0.3 to 3 Si-bonded acyloxy, hydrocarbonoxy or ether-containing hydrocarbonoxy radicals, any remaining Si valencies being satisfied by Si-bonded oxygen or hydrocarbon (saturated or unsaturated) or halohydrocarbon radicals. The functional radicals are preferably those which are readily hydrolysable at room temperature. The primers can be used alone or, preferably, as solvent solutions. The siloxane composition used may be any room temperature curing or heat curing composition, e.g. the combination of an acid-free diorganopolysiloxane, a silicate and a metal carboxylate, as disclosed in Specification 764,246; the combination of a diorganopolysiloxane containing Si-bonded -OH groups, 2-ethoxy-ethylsilicate and a metal carboxylate, as disclosed in Specification 844,128; the combination of an acid-free diorganopolysiloxane, an alkoxy-polysilicate and a condensation product of an aldehyde and an amine, as disclosed in U.S.A. Specification 2,833,742; the combination of an organohydrogen siloxane, a diorganopolysiloxane containing at least 2 SiOH groups and a metal carboxylate, as disclosed in Specification 804,199; the diacyloxy-terminated diorganopolysiloxanes disclosed in Specification 862,576; the foam-producing combination of a diorganopolysiloxane contain both SiOH and SiH and a stannous carboxylate, as disclosed in Specification 798,669; and the combination of a liquid vinyl-terminated diorganopolysiloxane, a copolymer of SiO2, Me3SiO0.5 and Me2 ViSiO0.5 units, a siloxane containing SiH and a Pt. catalyst, as disclosed in Specification 945,580 (Me= methyl and Vi=vinyl). In a typical example (1) the primer was made by reacting a trimethyl-siloxy-end-blocked-methyl hydrogen polysiloxane with vinyl-trimethoxysilane in the presence of chloroplatinic acid.ALSO:A process for coating surfaces comprises (1) applying to a surface a liquid coating of a primer comprising an organosilicon compound containing per Si atom an average of from 0,2 to 1 Si-bonded hydrogen and from 0,3 to 3 Si-bonded acyloxy, hydrocarbonoxy or ether-containing hydrocarbonoxy radicals, any remaining Si valencies being satisfied by Si-bonded ox