Reducing molecular weight distribution of polyether glycols by short-path distillation
US5302255A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 15, 1992 |
| Grant date | Apr 12, 1994 |
| Priority date | — |
| Expiry date | Sep 15, 2012 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S159/16
- WIPO fieldChemical engineering
- WIPO sectorChemistry
Abstract
Polyether glycols, especially poly(tetramethylene ether) glycol (PTMEG) having a narrow molecular weight distribution of about 1.25 to 1.80, or dispersity of 1.05 to 1.90, are made by a process involving distilling the low molecular weight fraction in unit operations including at least one short-path distillation evaporator. Two short-path distillation evaporators, in series, are desirable if significant narrowing of the PTMEG is required. In these units, PTMEG is subjected to temperatures in the range of 270.degree.-400.degree. C. with the hold-up time varying between 10-200 seconds. The required vacuum to force the separation of the low molecular weight PTMEG varies between 0.001 mm and 1.0 mbar. PTMEG residue from the distillation unit is also characterized by its low water content and low concentration of oligomeric cyclic ethers.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.