Process for preparing a styrenic resin

A process for preparing a styrenic resin by a continuous bulk or solution polymerization method, said resin having a rubber content of 0.1 to 4.5 wt. % which process comprises:

• (i) continuously charging into a reactor a feed containing 80 to 45 parts by weight of a vinyl aromatic monomer, 15 to 50 parts by weight of a vinyl cyanide monomer, 0 to 40 parts by weight of a copolymerizable monomer, and 0.1 to 6 parts by weight of a powdery rubber graft copolymer (A), based on a total of 100 parts by weight of said monomers, wherein said powdery rubber graft copolymer (A) has a weight average particle size of 0.05-0.8 .mu.m and is prepared by coagulating and drying a rubber graft copolymer latex (a), wherein said rubber graft copolymer latex (a) is made from graft polymerization of vinyl aromatic monomer and vinyl cyanide monomer in the presence of dienic rubber latex;
• (ii) charging to said reactor 0.1 to 10 parts by weight of an acrylic-based copolymer (B) based on a total of 100 parts by weight of said monomers, wherein said acrylic-based copolymer (B) is rigid and soluble in said monomers and is prepared from at least one monomer selected from methyl methacrylate and acrylonitrile, and a vinyl aromatic monomer, and wherein said acrylic-based copolymer (B) is added to said feed in an amount sufficient to facilitate the introduction of the feed into the reactor by preventing agglomeration of said copolymer (A) and thereby improving the dispersion of said copolymer (A) in said feed;
• (iii) polymerizing said feed in the presence of said acrylic-based copolymer (B) to a conversion of 40 to 90 wt. %;
• and (iv) removing the unreacted monomers and volatile components from the polymerized mixture.