Patent ID: 7105602

Claim:
A processing aid for thermoplastic resin having a weight average molecular weight of 10,000 to 300,000, which is obtained by multi-step emulsion-polymerizing a composition consisting essentially of 0.1 to 5% by weight of a (meth)acrylate having an oxygen atom in addition to an ester bond, 10 to 99.9% by weight of another alkyl acrylate, and 0 to 89.9% by weight of another vinyl monomer copolymerizable therewith, in the presence of an organic peroxide having a tertiary-butyl peroxy group as a polymerization initiator, wherein the other vinyl monomer copolymerizable therewith is at least one vinyl monomer selected from the group consisting of alkyl (meth)acrylates, aromatic vinyls, acrylonitrile and methacrylonitrile, and wherein an amount of the organic peroxide having a tertiary-butyl peroxy group is 0.1 to 5 parts by weight based on 100 parts by weight of the entire monomers.