Process for the preparation of creep-resistant polypropylene block copolymers
US6221974A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 21, 1998 |
| Grant date | Apr 24, 2001 |
| Priority date | — |
| Expiry date | Dec 21, 2018 |
Classification
- Technology area (CPC F)Mechanical Engineering; Lighting; Heating
- CPC primaryF16L57/02
- WIPO fieldMechanical elements
- WIPO sectorMechanical engineering
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.degree. C. using: a catalyst system of the above-mentioned type; a portion of ethylene or C.sub.4 -C.sub.10 -.alpha.-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.sub.10 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.sub.2 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.degree. 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.sub.2 value of between 30 and 300 g/10 min for said polymer, if this step is performed first, or to a MFR.sub.2 …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.