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US 4,061,694 AGranted
Low temperature impact strength molding compositions
AssigneeDart Industries Inc.
InventorEugene Gennaro Castagna
Life of this patent
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Abstract
Polypropylene molding compositions of improved impact strength are obtained by subjecting certain block copolymers of ethylene and propylene to controlled oxidative degradation.
Claims14
A polypropylene molding resin of improved low temperature impact strength obtained in a process comprising
- I. providing a block copolymer having a melt flow rate in the range of from about 0.5 to about 1.5 grams per 10 minutes at 230.degree. C and containing
- a. from about 60 to about 95 percent by weight of a polypropylene block and
- b. from about 5 to about 40 percent by weight of a block of a random copolymer of ethylene and another .alpha.-olefin, wherein the content of ethylene derived units in said random copolymer block ranges between 30 and 60 weight percent,
- Ii. contacting said block copolymer with an oxygen containing compound selected from air, elemental oxygen, inorganic peroxide, organic peroxide, or mixtures thereof;
- melting and working the mixture of oxygen containing compound and block copolymer in a high shear zone to subject the mixture to substantial oxidative degradation, and
- Iii. recovering a polymer product having a melt flow rate which is higher than that of the block copolymer provided in Step I.
3 more elements
Dependencies are inferred from the claim text.