Lightweight reinforced RIM polyurethane substrates are increasingly being specified for fully covered automotive applications such as interior door panels, instrument panels, and package shelves. In addition to offering a 30-40 % weight reduction over conventionally used substrate materials, consolidation in manufacturing steps are achieved by molding direct to polyvinylchloride (PVC), polyurethane (PU) and/or textile coverings. Weight reduction and consolidation of manufacturing steps lead to considerable part cost savings. Styling trends toward complex, deep drawn door panels, integrated with instrument panel modules, are easily fulfilled with low pressure RIM.
Existing RIM capital used to produce RRIM fascia, cladding, and body panels is suitable to manufacture low density RRIM substrates (LD-RRIM). The LD-RRIM process, which also incorporates particulate reinforcement in the liquid resin stream, reduces costs by up to 13% over low density structural RIM (LD-SRIM) which uses fiberglass mat inserts.
The LD-RRIM process uses two-stream lance cylinders for resin injection. It thus allows molders to take advantage of established RIM recycling technology by incorporating pulverized PVC covered LD-RRIM mold scrap into the original part. Covered polyurethane door panels, stripped of metal fixtures, can be granulated and pulverized using standard grinding equipment. The powdered plastic “regrind” can be added as an inexpensive extender, at the time of filler addition, to further reduce material costs. Of all one-step, covered door panel processes, the LD-RRIM approach is the only process that has demonstrated the incorporation of covered substrate scrap as regrind, without first separating the substrate from coverstock. The “regrind process” is a safe, simple, and economical method for recycling vinyl covered LD-RRIM polyurethane components.