Aqueous silicone emulsion, of use as base for preparing a water-repellent and anti-adhesive paper coating, process for preparing an emulsion of this type and anti-adhesive coatings

摘要

The invention concerns an aqueous silicone emulsion for the preparation of anti-adherent coating on fibrous or non fibrous supports for example paper. Said emulsion comprises polyorganosiloxanes (POS) with Si-vinyl units and POS with SiH units, cross-linkable by polyaddition in the presence of a platinum catalyst. Known emulsions of this type are not stable and tend to be cross-linked prematurely and to produce a chemical foam. Said undesirable phenomena constitute a great nuisance for industrial machines used for anti-adherent paper coating. The invention solves this problem by proposing an emulsion having the following composition: POS A with the Si-Vi units, POS B with SiH units, platinum catalyst C, agent T for setting and maintaining pH between 5 and 9, preferably between 6 and 8; T being preferably a buffer solution (NaHCO₃); an emulsifying agent D (polyvinyl alcohol); optionally a polyaddition inhibitor E and optionally other additives F such as filler, biocide, antifoam, anti-freeze, colouring agent, synthetic latex and the like. The invention also concerns a method for preparing said emulsions and methods for coating supports, for example paper, using said emulsion. The invention is applicable for making paper anti-adherent.