Polypropylene block-copolymer resin and process for producing it
US6306973A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 3, 2000 |
| Grant date | Oct 23, 2001 |
| Priority date | — |
| Expiry date | Feb 3, 2020 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC08F210/06
- WIPO fieldMacromolecular chemistry, polymers
- WIPO sectorChemistry
Abstract
Polypropylene block-copolymer resin exhibiting high melt tension and improved moldability with balanced stiffness and impact resistance may be molded at high speed into large-sized articles, including, stretched films, with good appearance and resistance to deformation. The block copolymer includes a higher molecular weight polypropylene segment, a lower molecular weight polypropylene segment and an ethylene .alpha.-olefin copolymer segment. When subjected to dissolution fractionation m paraxylene, a large proportion is insoluble at 23.degree. C. but soluble at 135.degree. C., and a smaller portion is soluble at 23.degree. C. The block copolymer has a melt flow rate of 0.01 to 5 g/10 min at 230 C. (2.16 kg) and a molecular weight distribution Mw/Mn of 6-20 and Mz/Mw of at least 3.5. A continuous multistage polymerization may be used to form the block copolymer.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.