Recycling of Mixed Color Automotive Thermoplastics

A method for recycling of mixed color automotive thermoplastic scrap into appearance automotive interior parts has been developed and shown to satisfy the following three requirements: 1) material performance 2) color appearance, and 3) economically sound. The technique developed is based on minimal separation of the colors into hues (groups of similar colors) and repigmenting to the desired color. The studies included computer formulations, laboratory verifications and plant runs. Plant runs were carried out to produce automotive interior doors (base level S-truck) with polypropylene (PP) regrind and B-pillar 325 parts with acrylonitrile-butadiene-styrene (ABS) regrind at the Delphi - Adrian plant. Two colors, ruby red and medium gray, were selected because they are the most difficult colors to match. The results of the plant runs demonstrated that color matching can be successfully achieved. The total color difference in CIELAB color space (DE) of the recycled automotive parts to GM color standards was less than 0.87 with compositions of 20% and 30% of a one hue dominant PP and ABS regrind fraction at less than 2% pigment loading. The recycled automotive parts also met other requirements for mechanical and physical properties specified by the GM standards including GM's UV resistance requirements.