Patent ID: 7776237

Claim:
A process which comprises forming a film from an aqueous emulsion of a polymer with core/shell structure, and then removing water from the aqueous film, thereby forming a polymeric film, wherein the polymeric film produces a visual effect upon reflection of electromagnetic radiation, and wherein the emulsion polymer is obtained by polymerizing monomers in at least one first stage (core monomers), then polymerizing monomers in at least one further, second stage (transition stage), and finally polymerizing monomers in a third stage which form a filmable shell (shell monomers), where, based on the percentage constitution of the monomer mixtures of the three stages, at most 30% by weight of the monomers of the first stage are identical with those of the third stage, and at least 5% by weight of the monomers of the second stage are identical with, respectively, those of the first and those of the third stage, and not more than 60% by weight of the monomers of the second stage are monomers absent in the first stage and also absent in the third stage, wherein said polymeric film comprises a matrix and discrete polymer particles distributed in the matrix, wherein the shells form the matrix and the cores form the discrete polymer particles.