Patent ID: 7226977

Claim:
A composition comprising: a thermoplastic polyolefin produced by polymerizing propylene and optionally ethylene in a least one first polymerization reactor to form a propylene homopolymer or random copolymer; and polymerizing ethylene and propylene in the presence of said propylene homopolymer or random copolymer in at least one subsequent polymerization reactor to form an ethylene/propylene rubber, said thermoplastic polyolefin comprising, about 60 percent to about 80 percent by weight of a xylene insoluble fraction comprising propylene homopolymer or random copolymer; and about 20 percent to about 40 percent by weight of a xylene soluble fraction comprising ethylene/propylene rubber, said xylene soluble fraction containing from about 25 percent to about 45 percent by weight of ethylene; and said thermoplastic polyolefin composition having a melt flow rate of at least 20 dg/min without visbreaking; wherein the ratio r of the molecular weight of the xylene soluble fraction to the molecular weight of the xylene insoluble fraction is about 1.4 or less as measured by the equation: r =Mw (XS) /Mw (XIS) where: Mw (XS) is the weight average molecular weight (Mw) of said xylene soluble fraction, and MW (XIS) is the weight average molecular weight (Mw) of said xylene insoluble fraction.