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US 4,291,138 AGranted
Production of modified polypropylenes
AssigneeMitsubishi Petrochemical Co., Ltd.
InventorsHideo Sato, Toshio Yagi
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Abstract
A modified polypropylene having improved impact resistance is obtained by producing, in the presence of a stereoregular polymerization catalyst and in three steps, two types of polypropylene blocks formed stepwise at different temperatures and then poly(ethylene or ethylene/propylene) block, the polymerization temperatures employed and the quantities of polymers produced in each step being in specific ranges.
Claims11
A process for producing a modified polypropylene in the presence of a stereoregular polymerization catalyst which comprises, in combination:
- Step 1 wherein propylene is polymerized at a temperature of not higher than 60.degree. C. to produce 0.5 to 30% by weight of a crystalline propylene polymer on the basis of the total polymerization product obtained in Steps 1 through 3;
- Step 2 wherein propylene is further polymerized at a temperature which is at least 10.degree. C. higher than that of Step 1 to produce 60 to 95% by weight of a crystalline propylene polymer on the basis of the total polymerization product in Steps 1 through 3, the quantity of the crystalline propylene polymer being the total quantity through Steps 1 and 2;
- and
- Step 3 wherein a member selected from the group consisting of ethylene and an ethylene-propylene mixture is polymerized to produce 5 to 40% by weight of an ethylene polymer on the basis of the total polymerization product in Steps 1 through 3, the ethylene content in the resulting ethylene polymer being 100 to 20% by weight.
1 more element
Dependencies are inferred from the claim text.