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Two new RIM polymers for fascia have been developed which provide significant improvements in processing and performance over commercial polyurethane/polyurea fascia systems. These polymers combine improved filler technology with new chemistries to yield a painted surface quality within five “DOI” units of steel, and they exhibit improved dimensional stability, without sacrificing low temperature impact strength. Compositional modifications of polyurethane precursors provide these benefits in polyurethane/polyurea (PU/UREA) RIM polymers. This chemistry yields high performance fascia desired by the automotive industry. Polyurea RIM systems, adapted from body panel technology, provide these same desirable characteristics and additionally offer the potential for self-release unassisted by external mold release agents. The increased cost of polyurea RIM chemistry is partially compensated by higher productivity.

Improved reaction injection molded (RIM) polyurea polymers for fascia have been developed which provide significantly longer mold fill times while maintaining the fast cure times sought by molders. These polymers have been formulated for use with or without fillers. In either case (filled or unfilled), surface quality comparable to painted steel can be achieved. Material performance data such as heat sag, low temperature impact, coefficient of linear thermal expansion and moisture absorption are compared for RIM polyurea and a commercial thermoplastic copolyester. The data illustrate that RIM polyurea fascia can be processed on existing equipment. These polymers provide superior performance over polyurethane/urea and equal performance with an economic advantage over injection molded engineering thermoplastic.

Reaction injection molded polyurethane chemistry has evolved to provide improved properties and processing while meeting competitive cost pressures. The concept of making parts thinner to reduce mass, thus costs, has been introduced previously and has been commercially reduced to practice. Now, the incorporation of light weight microspheres into RIM parts lowers specific gravity equal to that of TPO, about 0.92 gm/cc. Meeting performance requirements with thinner and lighter RIM materials while retaining the superior paintability and design flexibility of RIM has now been demonstrated. New understanding of polymer performance and continued development of filler technology make these unique and effective composites possible. Properties, processing, and field experience with these systems will be discussed.