Patent ID: 9714314
Date: 2017-07-25
CPC Classifications: C08F,C08L

Claim:
1. A core-shell copolymer impact modifier particle having a particle size between 170 and 350 nm and a pH between 6 and 7.5 comprising one polymeric rubber core comprising at least partially crosslinked isoprene or butadiene and optionally styrene, and at least two polymeric layers wherein at least one polymeric layer is an outermost thermoplastic shell layer having a Tg greater than 25° C., each layer having a different polymer composition, wherein at least one layer is a gradient zone produced in a polymerization stage reaction in which mostly a first monomer of styrene is incorporated during an initial stage of polymerization while increasing the amount of methyl methacrylate second monomer until mostly or entirely methyl methacrylate is incorporated during polymerization of a final stage, forming the gradient zone, and wherein the glass transition temperature of the polymeric core is under 0° C.