Lid stock for “to go” containers is currently produced using 11 mil HIPS sheet at forming rates of 18-20 cycles per minute. The users of lid stock would like to have parts with better chemical resistance to reduce the occurrence of leaking lids when used in oily food applications. Using polypropylene would enhance ESCR properties, which would improve performance in many food contact applications. However, polypropylene alone has not been able to provide a cost effective solution because the typical minimum achievable gauge is 16-18 mil with forming rates of only 8-10 cycles per minute.
This part, produced with a blend of 85% PP/ 15% UPESTM resin has achieved part thicknesses of 11 mil and forming rates of 15+ cycles per minute, therefore providing a solution with enhanced ESCR properties at costs comparable to HIPS. In addition, the PP/UPES blend is able to produce 13% more parts using the same weight of resin because the density of the PP/UPES parts is lower than that of HIPS.