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TPO (thermoplastic olefin) composite for rear bumper back beams was developed. In this study, the composition of PP (polypropylene), rubber and mineral fillers was optimized to minimize the intrusion and the failure after crash. The optimization of the composition was achieved using the mixture design of experiments. The physical properties of TPO composites with various compositions were investigated and the effect of each material on the crash performance of back beam was studied through CAE (computer-aided engineering). The back beams made of the optimized TPO composite for a subcompact car were prepared for the ECE 42 crash test and the TPO-based back beam showed even better performance than conventional PC/PBT-based counterpart. In addition, the newly developed composite has delivered a 15 ~ 40% cost saving and 4 ~ 10% weight reduction versus conventional PC/PBT and GMT (glass mat-reinforced thermoplastic).

Physical properties of waterborne soft feel coatings for instrument panel were investigated. Soft feel coatings give warm and velvet touch for cold and hard plastic materials. A waterborne soft feel coating is composed of two parts. Part A contains polyester polyurethane dispersion (PE-PUD), OH-functional water dispersible polyurethane resin (PC-PUD) and OH-functional water dispersible alkyd resin (OH-PA). Part B contains hydrophilic hexamethylene diisocyanate trimer (HHDI). The soft feeling of a coated panel is related with the amounts of PC-PUD and OH-PA. The physical properties of coated panel are controlled by the NCO/OH ratio from Part A and Part B. The results from all reliability tests satisfied soft feeling, scratch, chemical resistance and fogging.

Physical properties of sprayed polyurethane skin for instrument panel were investigated. Optimized sprayed PU(polyurethane) composition for instrument panel was determined by reaction speed measurement, which were polyol of 6000 molecular weight and modified MDI (NCO=25%). For making sprayed PU skin, raw material was sprayed from 15 cm of distance, at 15 g/min of spraying rate, on 70°C of mold, with 75°C of raw material. Sprayed PU skin had lower density than PVC skin when investigating cross sections of skins using scanning electron microscope (SEM). But the reliability test results satisfied all the specification requirements like scratch, chemical resistance, contamination resistance and fogging. Tensile strength, hardness and elongation of sprayed PU skin were slightly changed during heat aging, but the changing rate was much smaller than those of PVC skin.