Blends of polycarbonate with rubber and monovinylidene aromatic copolymers

Claim 1

A heterogeneous blend comprising the following components: (1) a polycarbonate of a dihydric phenol blended with (2) a rubber component, (3) an anhydride copolymer of a monovinylidene aromatic monomer and an α,β-ethylenically unsaturated anhydride and (4) a compatible polymer of a polar monomer other than an anhydride; said rubber component containing a copolymer of a rubber polymer blocked or grafted with a portion of the anhydride copolymer and/or the polymer of the polar monomer wherein said block or graft copolymer is present in an amount sufficient to measurably increase the impact resistance of the blend, said polar monomer being a polymerizable ethylenically unsaturated organic compound which bears a polar group having a group moment in the range from about 1.4 to about 4 Debye units determined in accordance with Smyth, C. P., Dielectric Behavior and Structure, McGraw-Hill Book Company, Inc., New York (1955), said component being present in proportions such that the blend has (a) a Gardner Dart impact strength of at least about 100 inch-pounds, (b) a notched Izod impact strength of at least about 3 foot-pounds/inch of notch, (c) a heat resistance of at least about 225° F. as determined by ASTM D-648 (unannealed at 66 pounds per square inch) and (d) a processability (injection pressure) less than about 7500 pounds per square inch at a mold fill time of 2.5 seconds as determined by the test procedure for Injection Pressure set forth in footnote (10) of Table I hereof.