Patent ID: 8668915
Filing Date: 2014-03-11
Classification: A61K,A61P,A61Q,C08F,C09D

Abstract:
1. A process for preparing a composition comprising an oil phase, an aqueous phase, at least one emulsifying system of the water-in-oil (W/O) type, at least one emulsifying system of the oil-in-water (O/W) type, in the form of a self-invertible latex, said composition comprising from 20% to 70% by weight of a branched or crosslinked polyelectrolyte, wherein said polyelectrolyte is a copolymer (P) of acrylamide with 2-acrylamido-2-methylpropanesulfonic acid partially or totally salified in a form of a salt selected from the group consisting of a sodium salt, a potassium salt and an ammonium salt, said process comprising the following steps: (a) preparing an aqueous phase (A) comprising acrylamide, 2-acrylamido-2-methylpropanesulfonic acid partially or totally salified in the form of a sodium salt, or of a potassium salt or of an ammonium salt, and, optionally, hydrophilic additives, said preparing of aqueous phase (A) comprising: (i) forming a solution by placing in water, acrylamide, said optional hydrophilic additives and 2-acrylamido-2-methylpropanesulfonic acid in a form of a salt selected from the group consisting of a sodium salt, a potassium salt and an ammonium salt, (ii) to said solution, adding free 2-acrlyamido-2-methylpropanesulfonic acid and an alkaline agent selected from the group consisting of sodium hydroxide, potassium hydroxide and aqueous ammonia, said free 2-acrlyamido-2-methylpropanesulfonic acid and said alkaline agent being added in alternating portions to said solution such that said solution has a pH that remains greater than 1 and less than 3, to obtain a first aqueous mixture A1 having a pH greater than 1 and less than 3, and (iii) adjusting the pH of said first aqueous mixture A1 to a pH between 5 and 6.5 to obtain said aqueous phase (A) and adding a branching or crosslinking agent; (b) emulsifying said aqueous phase (A), in an organic phase comprising a surfactant system of the water-in-oil (W/O) type, the oil intended to be present in the final composition, optionally a volatile oil, and optional hydrophobic additives, to form a water-in-oil emulsion (B), said water-in-oil emulsion (B) comprising monomers; (c) polymerizing the monomers in said water-in-oil emulsion (B), said polymerizing being initiated by introducing a free-radical initiator into said emulsion (B), to form an inverse latex (L1) of said copolymer (P); optionally, (d) concentrating by distillation of said inverse latex (L1) of said copolymer (P) until said volatile oil has been removed, to form an inverse latex (L2) of said copolymer (P); and (e) introducing an emulsifying system of the oil-in-water (O/W) type at a temperature below 50° C., in said inverse latex (L1) of said copolymer (P), or optionally in said inverse latex (L2) of said copolymer (P), to form a self-invertible inverse latex (L3) of said copolymer (P).