Polysulphide polymer sealant composition and process

摘要

1 to 3.5 weight per cent of a compound where R1 and R11 are C1- 4 alkyl, R is C1- 7 alkylene, n is 2 or 3, n1 is 1 or 2 and n11 is 0 or 1 is used as an adhesion-promoting additive for curable liquid polysulphide polymers. It may be incorporated in the polymer or applied as a primer coat to a substrate to which the polymer is subsequently applied. Such polymers are described in U.S. Patent Specification 2,466,963. Specified curing agents therefor are polyepoxides, Pb, Ca and Ba peroxides, TeO2 and chromate salts. The polymer may also contain fillers, plasticizers, pigments, U.V. stabilizers and cure accelerators. Exemplary compositions contain stearic acid, chlorinated hydrocarbon plasticizer, hydrated silica and (a) calcium carbonate and stearate, TiO2 and sulphur or (b) carbon black, and are cured with PbO2.ALSO:The adhesion of coaings of polysulphide polymers to substrates is enhanced by using a mercaptoalkyl polyalkoxy silane wherein R' and R" are C1-4 alkyl groups, R is a C1-7 alkylene group, n is 1 or 2, n" is 0 or 1, n is 2 or 3 and n' + n" + n=4, as adhesion promoter which may be applied as a primer coat to the substrate or incorporated in the polysulphide polymer. The polysulphide polymers are those described in U.S. Patent 2,466,963 which are liquid polythiopolymercaptan polymers. Specified substrates are wood, glass and metals e.g. aluminium, iron, steel and zinc or chrome coated iron or steel.