SILANE/SILOXANE EMULSIONS FOR MASONRY SURFACES

摘要

An aqueous silane/siloxane emulsion comprising (a) 4 % to 50 % by weight of an alkylalkoxysilane of the formula Rn-Si-R<1>(4-n) wherein, R is a hydrocarbyl group containing from 1 to 20 carbon atoms; R<1> is an alkoxy group containing from 1 to 6 carbon atoms; and n is 1 or 2 (b) 15 % to 95 % by weight of water; (c) 0 % to 5 % by weight of an emulsifier which is an amine soap; and (d) 1 % to 30 % by weight of a siloxane which is either a polyalkylsiloxane produced from a monomer of the general formula R-Si-(OR<2>)3 where R is defined above and R<2> is a hydrocarbyl group having 1 or 2 carbon atoms; or a silicon fluid of the formula (R<3>XSiO4-x/2)y where R<3> is a hydrocarbyl group containing from 1 to 6 carbons atoms, x is 1 or 2 and y is 2 or more; with provisos that: when the siloxane is a polyalkylsiloxane and no emulsifier is present, a polymerisation catalyst which is a mixture of a benzenesulfonic acid and an alkali metal salt of a benzenesulfonic acid is employed to produce the polyalkylsiloxane; and when the siloxane is a silicone fluid at least 0.5 % by weight of emulsifier is present in the emulsion. A process for rendering permeable masonry water repellent by applying the emulsion to its surface and curing the composition.