PROCESS FOR REMOVING THE SOLVENT OR SUSPENDING MEDIUM FROM POLYMERIC SOLUTIONS OR SUSPENSIONS; AND THE POLYMER, ORGANIC SOLVENT AND ORGANIC SUSPENDING MEDIUM RECOVERED THEREBY.

摘要

A process for removing organic solvent or suspending medium from a solution or suspension of a polymer in said solvent or suspending medium, which process comprises the following steps: (a) mixing in a stripping vessel the solution or suspension of the polymer in the organic solvent or suspending medium with vigorous stirring with water kept hot by the introduction of steam, the mixing being regulated so as lo maintain the resulting suspension of polymer in water at a temperature of about 5C. greater than the boiling temperature of the azeotrope of water and organic solvent or suspending medium, under the existing conditions, and allowing steam and organic solvent or suspending medium to escape from the mixture; (b)  stopping the mixing when the ratio of the water to the polymer has achieved a value in the range from 20 :1 to 6: 1 (c)  introducing, under the conditions specified in  step temperature to reach a value about 2C lower than the toiling temperature of the azeotrope of water and organic solvent or suspending medium, and allowing steam and organic solvent  or spending  medium  to  escape  from  the (d)  subjecting, under the conditions  specified in step (b),  the suspension  in  water of the substantially organic solvent free or organic suspending medium-free polymer to filtration so as to separate polymer crumbs and hot water (e) recycling the hot water from step (d) to the mixture being subjected to solvent-removal or organic suspending medium-removal until a polymer: water ratio of not more than 1 : 100 is reached in the mixture.