Method for producing polylactic acid and apparatus used therefor
US5880254A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 8, 1996 |
| Grant date | Mar 9, 1999 |
| Priority date | — |
| Expiry date | Jul 8, 2016 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02P20/582
- WIPO fieldMacromolecular chemistry, polymers
- WIPO sectorChemistry
Abstract
A method for producing a polylactic acid includes the steps of (a) crystallizing polylactic acid pellets obtainable by direct polymerization of lactic acid or ring-opening polymerization of lactide; and (b) removing low-molecular components having a weight-average molecular weight of 1,000 or less in the resulting crystallized, solid polylactic acid pellets by gasifying the low-molecular components to obtain polylactic acids with substantially no low-molecular components. In this method, an apparatus for removing low-molecular components in polylactic acid pellets includes a crystallizing means for maintaining a temperature between equal to or higher than a glass transition temperature of polylactic acid pellets and equal to or lower than the melting point thereof, while fluidizing the polylactic acid pellets; and a reactor for allowing a heated inert gas and/or heated air to pass through the resulting crystallized, solid polylactic acid pellets obtained by the crystallizing means.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.