Verfahren zur Molekulargewichtsreduzierung hochmolekularer Polyäthylene in der Pulverphase

摘要

LOW MOLECULAR WEIGHT POLYETHYLENE. M1-. Controlled reduction of the mol.wt. of high mol.wt. polyethylene (limiting viscosity number (LVN) = 3.5 to 5 dl/g) by oxidation at 110-135 degrees C of finely powdered material (10 mu to 2 mm dia) dampened with 0.1-20 (pref. 1-10) wt.% of a solvent. Esp. useful for reducing polyethylenes of density >0.94 g/mm3 to a LUV of 1.5 to 3.5 to facilitate processing. Similar to known processes for degrading polypropylene or polyisobutylene, the equipment required is less massive and expensive than mechanical degradation by extrusion or milling, and less solvent wastage/recovery is involved than with solution oxidation techniques. The degree of degradation is easily controlled by varying temperature or residence time in the dampened (and partially compacted) powder zone.