IMPROVED RUBBER MODIFIED MONOVINYLIDENE AROMATIC POLYMER COMPOSITIONS

摘要

The present invention is an improved rubber-modified polymeric composition comprising: (a) a continuous matrix phase comprising an interpolymer of a monovinylidene aromatic monomer and an ethylenically unsaturated nitrile monomer; and (b) from 5 to 40 weight percent, based on the total weight of said polymeric composition, of a rubber in the form of discrete rubber particles dispersed in said matrix, wherein the dispersed rubber particles comprise: (1) at least 33 weight percent based on the total rubber content, of a mass rubber particle component having a volume average particle diameter o f from 0.15 to 0.40 micron; (2) from 15 to 67 weight percent based on the tota l rubber content, of a small-particle emulsion rubber component having a volum e average diameter of from 0.05 to 0.30 micron; and (3) from 0 to 35 weight percent based on the total rubber content, of a large emulsion particle rubb er component having a volume average diameter of from greater than 0.30 to 2.0 micron; wherein the rubber particles of the composition have an average ligh t absorbance ratio of less than 1.4.