Rotomolding process with reduced cycle times
US7201864B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jul 8, 2004 |
| Grant date | Apr 10, 2007 |
| Priority date | — |
| Expiry date | Nov 5, 2024 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC08L2205/025
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
The cycle time for a rotomolding process is improved through the use of a molding material comprising a blend of at least two polyethylenes having narrow molecular weight distributions and homogeneous comonomer distributions. Alternatively, the molding temperature may be reduced to conserve energy and reduce energy costs. The polyethylene blend also has a narrow molecular weight distribution of less than 3 and a density of from 0.930 to 0.950 g/cc. Rotomolded parts prepared from the blend composition have excellent impact resistance and are also resistant to warpage. A preferred process employs a blend composition which contains a blend component having a higher molecular weight and a lower density than another blend component—this blend may be used to prepare rotomolded parts with warpage resistance and improved environmental stress crack resistance (ESCR). A highly preferred process uses a blend composition which further contains a minor amount (from 0.5 to 10 weight %) of a third ethylene blend component which has a higher molecular weight and density—this highly preferred composition may be used to prepare rotomolded parts having warpage resistance, very good ESCR and comparati…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.