Novel Material and Process for Replacement of Lead Products

Lead is a soft, low melting point, high density, and inexpensivve material that can be easily shaped. All these attributes have made lead useful in appplications such as bullets, fishing rod sinkers, weights for balancing tires, hunting shots, etc. In spite of all these attractive properties, lead is a major environmental contaminant due to its toxicity. Leaed is toxic and cna be stored in biological tissues with devestating results. Extensive use of lead in common applications has resulted in this material winding up into the food chain (through its deposition on soil, waters, and plants). One high volume application of lead is in the automotive sector where lead is used as balancing weights (0.25 ounce to 3 ounce). When these weights fall off the wheels, it adds pure lead to the ground which is extremely toxic. As the lead is easy to melt and form, many of these weights are converted into weights for fishing line sinkers. Game hunting using lead shots has become another major source of environmental contamination where the unused lead is deposited all over the surface soil as well as wometimes in water. It is, therefore, of utmost importance that an environmentally benign substitute for lead that can be formed into complex shapes be quidkly established. Ideally if the substitute material can be recycled and if a part of it can degrade in an environmentally benign manner, it would provide a tremendous advantage. The Phase I project proposes to develop a conceptual composite material from a special spherical high density inorganic particulate material ( benign relative to lead) that is highly loaded in a special organic thermoplastic material. This special mix would have the density of lead-based allooys (around 11 g/cc), will be ingection moldable into complex shapes, have the ability to be recycled, and in special cases part of it can degrade in a benign menner. The success in Phase I will provide a material and process than will be capable of replacing lead-based alloys in numerous applications including tire balancing weights, shots used in hunting, bullets for test ranges, rediation shield, fishing line sinkers, etc. It is expected that lead will suffer the same fate as "asbestos" and its use wil be gradually phased out from numerous applications before 2010. This investigation will provide the US industry with an alternative material that has numerous attributes and is manufacturing friendly.