Patent ID: 7927615

Claim:
A method of thickening a cosmetic comprising adding thereto a microgel, said microgel being produced via radical reverse phase emulsion polymerization of a mixture of water soluble monomers of a dialkylacrylamide represented by general formula (1) and an anionic acrylamide derivative represented by general formula (2) as follows: wherein R1 denotes a H or methyl group; R2 and R3, independent of each other, denote a methyl, ethyl, propyl, or isopropyl group; wherein R4 and R5, independent of each other, denote a H or methyl group, R6 denotes a straight chain or branched alkyl group having 1-6 carbon atoms, and X denotes a metal ion or NH3; dissolved in a dispersion phase in a polymerization system composition having an organic solvent or an oil component as the dispersion medium and water as the dispersion phase, wherein said polymerization system composition contains a surfactant and forms a single phase microemulsion or fine W/O emulsion said polymerization being carried out in a thermodynamically stable single microemulsion region or a metastable fine W/O emulsion region of a phase diagram for the polymerization system composition, wherein said microgel has: (a) an apparent viscosity of a microgel aqueous dispersion (0.5% mass percentage of the microgel at 25° C.) of 10,000 mPa·s or higher at a shear rate of 1.0 s −1 ; (b) an apparent viscosity of a microgel ethanol dispersion (0.5% mass percentage of the microgel at 25° C.) of 5,000 mPa·s or higher at a shear rate of 1.0 s −1 ; and (c) a dynamic elastic modulus of a microgel aqueous or ethanol dispersion having 0.5% (mass percentage) at 25° C. satisfying a relationship G′ (stored elastic modulus) greater than G″ (loss elastic modulus) at a strain of 1% or less and a frequency range of 0.01-10 Hz.