Dual Injection Molding and Automotive Glazing

This paper outlines the requirements for obtaining a transparent PC-PMMA sandwich composite for use in an automotive glazing application. It is shown that transparency can be maintained if turbulent interfacial mixing is kept to a minimum through slow injection and careful matching of the skin and core material rheologies. If significant interfacial mixing is present then the difference in refractive indices of the two materials must be less than ± 0.002 for transparency to be maintained. The melt temperature difference between skin and core material can be no more than ± 30°C otherwise thermal degradation occurs along with difficulties in achieving full cavity fill.