The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 24, 2001
Filed:
Dec. 21, 1998
Borealis Technology Oy, Porvoo, FI;
Abstract
The invention relates to a process for the preparation of a creep-resistant polypropylene by means of the following steps: (a) copolymerizing propylene and ethylene into a random copolymer at 40 to 110° C. using: a catalyst system of the above-mentioned type; a portion of ethylene or C,-C,-&agr;-olefin leading to 1.0 to 10.0% by weight of ethylene repeating units in said random copolymer; and no or a minimal amount of hydrogen leading to a MFR,value of between 0.01 and 5.0 g/10 min for said random copolymer, if this step is performed first, or to a MFR,value for said polypropylene of between 0.05 and 0.40 g/10 min, if this step is performed after step (b); the proportion of random copolymer of this step being from 20 to 80% by weight of said polypropylene, (b) polymerizing propylene at 40 to 110° C. using: a catalyst system of the above-mentioned type; no or a minimal portion of ethylene leading to 0.0 to 1.0% by weight of ethylene repeating units in the polymer resulting from this step; and an amount of hydrogen leading to a MFR,value of between 30 and 300 g/10 min for said polymer, if this step is performed first, or to a MFR,value for said polypropylene of between 0.05 and 0.40 g/10 min, if this step is performed after step (a); the proportion of polymer of this step being from 80 to 20% by weight of said polypropylene.