Separation of polyethylene terephthalate and polyvinyl chloride using supercritical carbon dioxide
US5462973A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 13, 1994 |
| Grant date | Oct 31, 1995 |
| Priority date | — |
| Expiry date | Jul 13, 2014 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02W30/62
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
A method for separating co-mingled polymeric materials, in particular polyethylene terephthalate (PET) and polyvinyl chloride (PVC) is described. The process involves selectively dissolving a supercritical fluid into one of the materials at the appropriate temperature and pressure. Upon rapid reduction of the system pressure, the selected material foams providing a change in density. Under ambient conditions, the polymeric materials having a large density difference can be separated by means of aqueous separation and flotation. The preferred supercritical fluid for the process is carbon dioxide, and PVC is the material into which the supercritical fluid is preferentially dissolved.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.