Aqueous dispersion of structured polymer in core / crust, its preparation procedure and its application in coatings

摘要

Aqueous polymer dispersion comprising polymer particles structured in core / cortex, capable of being obtained by emulsion polymerization of at least two monomer compositions 1 and 2, in at least two stages, said dispersion being characterized in that said demonomeric compositions 1 and 2 produce polymers P1 and P2 that have respective glass transition temperatures Tg1 and Tg2 being Tg1 less than or equal to 30 ° C and Tg2 being greater than or equal to 80 ° C, and varying the difference Tg2-Tg1 from 50 to 200 ° C, and said polymerization being performed in presence of at least one anionicophosphate surfactant, and have: a) either in the polymer phase P1, b) or in the polymer phases P1 and P2, with the condition in this case that the weight ratio: phosphate anionic surfactant in P1 / phosphate anionic surfactant of P2 is greater than 1, the weight rate of said phosphate anionic surfactant ranging from 0.5 to 5% by weight, with res pertaining to the total weight of monomers of said dispersion, with said phase P1 representing a rate that is going to be 75 to 85% by weight of the total P1 + P2, and P2 representing a rate ranging from 15 to 25% by weight of the total of P1 + P2.