Process for recovery of bisphenol-A from thermoplastic polymer containing dihydric phenol units
US5675044A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 1, 1996 |
| Grant date | Oct 7, 1997 |
| Priority date | — |
| Expiry date | Jul 1, 2016 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02W30/62
- WIPO fieldOrganic fine chemistry
- WIPO sectorChemistry
Abstract
A method of recovering dihydric phenol, particularly bisphenol-A, from compositions containing the reaction residue of bisphenol-A units which method comprises: PA1 a. granulating a bisphenol-A containing polymer; PA1 b. treating the particles with an alcohol, or any other organic swelling solvent miscible with water and easily distilled off from an aqueous solution, preferably a C.sub.1 -C.sub.10 alcohol for a time sufficient to swell the particles; PA1 c. contacting the swelled particles with a ammoniacal solution at a temperature of at least about 25.degree. C. depending on the swelling solvent employed in order to selectively sever the ester bonds of the bisphenol-A residue units; PA1 d. separating the liquid phase from the solid phase; PA1 e. distilling ammonia and swelling solvent from the liquid phase of d. above, thus obtaining an essentially aqueous solution with dissolved urea and partially precipitated bisphenol-A; PA1 f. adding sufficient water to the residue of e. above to precipitate bisphenol-A thereby forming a liquid and solid phase; PA1 g. recovering the solid phase of bisphenol-A; and PA1 h. drying the bisphenol-A. Since urea is soluble in water, urea goes into s…
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