Method for producing saponified ethylene-vinyl acetate copolymer
US6609528B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Aug 22, 2001 |
| Grant date | Aug 26, 2003 |
| Priority date | — |
| Expiry date | Dec 29, 2021 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC08F2800/10
- WIPO fieldMacromolecular chemistry, polymers
- WIPO sectorChemistry
Abstract
A method for producing a saponified ethylene-vinyl acetate copolymer, which comprises washing chips of a saponified ethylene-vinyl acetate copolymer. In this method, the chips containing impurities and methanol are introduced into a washing column through an upper portion thereof; water is introduced into the washing column through a lower portion thereof; while the methanol concentration in the solution in the upper portion of the column is maintained in the range of 25 to 45 wt % and the chips are allowed to fall (i.e. sink) from the upper portion of the column, methanol and water with at least a part of the impurities are discharged from the column through an upper portion thereof; and the chips are taken out of the column through a lower portion thereof with water that contains methanol in a lower concentration than the methanol concentration in the solution in the upper portion of the column. According to this method, a saponified ethylene-vinyl acetate copolymer is produced efficiently and safely, and visual imperfections are inhibited when the saponified copolymer is formed into a molded product such as a film.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.