A Versatile New Resin System for Class A Body Panels

Advances in surface appearance, production efficiencies and overall part quality are required to keep thermoset composites competitive as key materials for the automotive industry. In response to these challenges, a versatile molding resin has been designed to meet the demanding requirements of the Nineties. Polyester resin MR 13006 lends itself well to the production of SMC, TMC and BMC molded parts. Class A surfaces have been obtained consistently with combinations of MR 13006 and Neulon T Plus^R. Diffracto^R and Loria^R readings under 85 along with good mechanical properties are achievable.

Compounds formulated with the MR 13006/Neulon T Plus^R combination can be molded by either compression or injection techniques, and they are characterized by fast cure rates and wide molding “windows.” High-quality surfaces can be obtained with a range of formulations and molding conditions, making these systems very well suited to commercial molding operations.

A study was conducted via a design of experiments to optimize compound formulations. The DOE resulted in the following conclusions: 1) a higher filler loading gave improved surface quality; 2) surface quality was inversely proportional to glass content and 3) directly proportional to filler loading. The optimum formulation projected by the design should yield excellent surface quality while maintaining good mechanical properties and SMC moldability.