Patent ID: 7507781
Filing Date: 2009-03-24
Classification: C08F,D21H,Y10S

Abstract:
1. A method of preparing a polymer by water-in-oil emulsion polymerization comprising: (a) preparing an oil phase comprising: at least one hydrocarbon; and a surfactant system wherein the surfactant system comprises at least one diblock or triblock surfactant to form an emulsion upon the addition of an aqueous phase; (b) preparing an aqueous phase comprising at least one ethylenically unsaturated anionic monomer and at least one ethylenically unsaturated anionic monomer and at least one ethylenically unsaturated nonionic monomer; (c) adding said aqueous phase (b) to said oil phase (c) to form an emulsion; and (d) causing the monomers in the emulsion to polymerize by free radical polymerization; wherein the diblock or triblock surfactant to monomer ratio is at least about 0.03 and the pH is adjusted to from about 2 to about 7 and wherein no additional crossing linking agent is added to the system, wherein the resulting polymer having a Huggins' constant (k′) determined between 0.0025 wt. % to 0.025 wt. % of said polymer in 0.01 m NaCl is greater than 0.75; and having a storage modulus (G′) for a 1.5 wt. % actives of said polymer solution at 4.6 Hz is greater tan 175 Pa.