Electret fibers and filter webs having a low level of extractable hydrocarbons

摘要

A method of making electret fibers, which method comprises the steps of:blending a polymeric material with a fluorochemical additive compound;extruding the blend at a temperature maintained below 290° C. to form extruded fibers; andannealing and charging the extruded fibers;wherein the polymeric material and extrusion conditions are selected such that the resulting fibers have a level of extractable hydrocarbon material that is less than about 3.0 weight percent based on the weight of the fibers.