EXTON, PA. - In a move that demonstrates the versatility of compounding, LNP Engineering Plastics Inc. has developed a family of plastic compounds that are so heavy they have created a packaging problem for the company. LNP designed a new line of high-specific-gravity composites to replace lead in a variety of applications, in automotive and consumer products.
Lead has a specific gravity of 11.3, and LNP's Thermocomp HSG resins have a specific gravity as high as 10, according to Jack Maher, Thermocomp product marketing manager. For comparison, GE Plastics said its Heavy Valox compounds have a specific gravity of 1.8.
``These products are like Heavy Valox on steroids. The key to these products is the compounding technology and the binding of the resins to the heavy fillers,'' Maher said.
The first products in the line are based on several resins with as much as an 80 percent filler, said George Niznik, LNP's vice president and director of re-search and development. Niznik declined to identify the filler, but he said it is not a heavy metal, and is a chemically inert, environmentally benign material that can be wetted fully by the resin.
LNP has found applications for the composites in consumer electronics, where one customer has replaced lead in a fly wheel on a tape drive. Another customer has used the heavyweight product to reduce resonance in cassette tapes, and one uses it to replace lead in an inertia activator for an automotive seat belt, Maher said.
However, Maher sees the sports market as one of the best for LNP's new products. Environmental activists have cited lead shot and lead left in water systems by fishermen as growing outdoor environmental hazards.
``This product is a perfect replacement for lead in bullets and shot and in fishing tackle, as an alternative to lead in sinkers,'' Maher said.
LNP supplies the compounds based on 14 resins, including polypropylene, nylon and polyetheretherketones, Maher said. However, the nylon grades have seen the greatest demand, he said.
The compounds are available with specific gravities of 1.5-10, and cost $2-$14.37 per pound. They can be injection molded or extruded. Even at their relatively high costs, Maher said, they are competitive because they can be molded in finished shapes, where metal products often require machining.
However, Maher said LNP has a problem: LNP's traditional shipping methods - bags and gaylords - are designed for compounds with typical specific gravities of less than 1.
``We have been thinking of shipping these one pellet at a time,'' joked Richard J. Burns, executive vice president and chief operating officer.
While declining to be specific, Maher said LNP has sought advice in packaging and shipping its HSG products from outside the plastics industry, in industries that deal with heavier products.