STIFF AND IMPACT RESISTANT COMPOSITIONS CONTAINING POLYPROPYLENE OR POLY ETHYLENE-PROPYLENE COPOLYMER AND CALCIUM CARBONATE FOR CLOSURES

摘要

Stiff and impact resistant closures derived from the stiff and impact resistant blends including poly(propylene) or poly(ethylene/propylene) and calcium carbonate; stiff and impact resistant compositions including poly(propylene) or poly(ethylene/propylene) and calcium carbonate; methods for increasing stiffness and impact resistance of a poly(propylene) or poly(ethylene/propylene) resin, or a closure; and a method for measuring the impact strength of a closure or a resin at a reduced temperature are disclosed. A presently preferred blend contains from about 40 to about 60 weight percent of poly(propylene) or poly(ethylene/propylene) and from about 25 to about 35 weight percent of calcium carbonate particles treated with fatty acid, the treated particles having a particle size of from about 2.5 to about 3.5 microns.