Synthetic fiber replacing talc in PP parts

Silvia Bubenikova, development engineer at Milliken's European headquarters of Gent, Belgium, told PlasticsToday that the filler, called Hyperform HPR-803, is a synthetic mineral fiber. Milliken is known in the plastics industry for its clarifiers and nucleating agents but the company's history and the bulk of its business =is in the textiles industry. The fibers are less dense than talc, she said, and also improve a part's scratch resistance. When talc is replaced one-for-one by weight with these fibers, the mechanical properties of a part remain or are improved, she said, but at a lower part weight. Bubenikova spoke with PlasticsToday at last week's Plastics in automotive engineering event in Mannheim, Germany.

Though the fibers can see use in any polyolefin, she said the most likely application would be in polypropylene parts, and specifically interior automotive parts. PP has made huge inroads in the past decade in automotive interiors, and typically these interior parts are filled with talc, but scratching them can leave a white scar that exist for the life of a vehicles.

The fibers are translucent and can be easily colored, more so than talc, according to Bubenikova. Many fiber-filled parts (think glass fibers) need a surface film or other handling to achieve top-notch aesthetics, or simply are destined for applications out of a passenger's sight, but she said the surface finish of PP parts molded filled with these synthetic fibers is attractive enough for use in cars without such handling.