Aqueous silicone dispersions and their preparation

摘要

An aqueous dispersion comprises a silicone composition dispersed in an aqueous phase. The silicone composition comprises a product of a reaction of (a) an alkenyl-containing organopolysiloxane having an average per molecule of at least 2 alkenyl groups and (b) an Si H containing siloxane having an average per molecule of at least 2 Si H moieties. The dispersion also comprises a hydrosilylation catalyst, a polymeric film former and a surfactant of molecular weight below 1600. The composition is stabilised in dispersion form by the surfactant dissolved in the aqueous phase and the polymeric film former, and is capable of forming a tacky layer on drying.

主权项

1. An aqueous dispersion capable of forming a tacky layer on drying, the aqueous dispersion comprising:
A) a silicone composition dispersed in an aqueous phase, the silicone composition comprising a product of a reaction of;
(a) an alkenyl-containing organopolysiloxane having an average per molecule of at least 2 alkenyl groups,
wherein the alkenyl-containing organopolysiloxane (a) is a branched siloxane comprising:i) one or more units of the formula SiO4/2;ii) from 15 units to 995 units of the formula Rb2SiO2/2 where units i) and ii) may be inter-linked in any appropriate combination; andiii) units of the formula RaRb2SiO1/2 where each Ra substituent is selected from the group consisting of an alkyl group having from 1 to 6 carbon atoms and an alkenyl group having up to 6 carbon atoms and where each Rb substituent is selected from the group consisting of an alkyl group having from 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an aryl group, an alkoxy group, an acrylate group and a methacrylate group, and(b) an SiH containing siloxane having an average per molecule of at least 2 SiH moieties; B) a hydrosilylation catalyst; C) a polymeric film former; and D) a surfactant of molecular weight below 1600;
wherein the silicone composition A) is stabilised in dispersion form by the polymeric film former C) and the surfactant D) dissolved in the aqueous phase.