On-line surface modification of polypropylene fibers by corona treatment during melt-spinning

On-line corona treatment of polypropylene (pp) fibers during melt-spinning is studied. After extrusion of PP filaments, collected fiber tow is subject ed to corona treatment prior to drawing, crimping, and cutting into staple fibers, and wettability, antistatic, and friction properties of treated fib ers are characterized. Corona treatment results in an average decrease of 5 -10 degrees in the advancing contact angle and of 10-25 degrees in the rece ding contact angle for water on fibers. With amounts of spin finish lower t han 0.2% by weight of fiber, treated fibers have considerably better antist atic properties than untreated fibers. Treated fibers have an order of magn itude lower electrical resistance and about 50% less static charge build-up during carding than untreated fibers. In addition, there is a sharp change in wetting and friction properties of fibers with corona treatment when th e amount of spin finish is between 0.12 and 0.13 wt %. These effects are at tributed to improved wetting of the treated fibers by spin finishes, leadin g to a more uniform spreading of finish agents on the fiber surface.