Method and device for cleaning an absorptive polyester

摘要

In a method for cleaning an absorptive polyester, the polymer is dissolved in a first solvent (12) and subsequently the polymer solution is brought into tight contact with a second solvent (41) in a turbulent shear field under the influence of strong shear forces. Here, the second solvent (41) represents a non-solvent for the absorptive polyester and is mixable with the first solvent (12) to an unlimited extent. Subsequently, the polymer suspension resulting from the addition of the second solvent (41) is conveyed onto or into a rotating, cylindrical screen body (71) of a drum shear screen (70) and then the moist polymer mass is removed from the screen body (71) and subsequently dried. The method is suitable for the production of absorptive polyester with a high degree of quality and may be performed in a cost-effective fashion on an industrial scale as well.

主权项

1. A process for purifying a resorbable polyester, comprising:
(a) dissolving the resorbable polyester in a first solvent to form a polymer solution, wherein the polyester is soluble in the first solvent; (b) intimately contacting the polymer solution with a second solvent under action of high shear forces in a turbulent shear field to form a polymer suspension, wherein the resorbable polyester is not soluble in the second solvent and the second solvent is miscible with the first solvent; (c) introducing the polymer suspension into a rotating, cylindrical screen body of a drum shear screen wherein said drum shear screen is obliquely positioned downward along its length relative to the horizontal plane of the body of the apparatus; (d) separating the polymer suspension into a moist polymer mass and a solvent mixture; (e) removing the solvent mixture through a liquid outlet; (f) conveying the moist polymer mass through the rotating, cylindrical screen body to a solid outlet of the drum shear screen wherein one or more helically attached conveyor rails and/or guide blades are present inside the rotating, cylindrical screen body; (g) separating the moist polymer mass from the screen body through and (h) drying the polymer mass to obtain a purified resorbable polyester.