Continuous process for expanding thermoplastic minipellets
US5753157A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 27, 1997 |
| Grant date | May 19, 1998 |
| Priority date | — |
| Expiry date | May 27, 2017 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC08J2323/10
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
The subject invention pertains to a continuous process for expanding thermoplastic minipellets, particularly polypropylene. The minipellets are continuously expanded by continuously charging and mixing water and minipellets in a slurry tank to form a slurry which is subsequently pressurized. A blowing agent such as butane is entrained into the pressurized slurry flow, which said slurry is then heated by a heating means, such as a shell and tube heat exchanger, to the softening point of the minipellets. The heated minipellets are given the time necessary for impregnation by permitting them to flow through one or more impregnation vessels. The impregnated minipellets are released through an orifice into an expansion vessel where the blowing agent flashes off, thereby expanding the minipellets.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.