Three new polyester resin formulations for automotive SMC are said to incorporate reactive toughening that dramatically reduces "paint pops" without sacrificing stiffness or strength. Toughness is built into the resin backbone, not achieved by adding rubber. Ashland Composite Polymers, Dublin, Ohio, supplies the resin "A" and "B" sides plus the recipe for the full SMC formulation. These are said to be the first low-density SMC systems based on a toughened resin. Arotran 720 is a toughened "medium-density" Class A system that reportedly gives 90% fewer paint pops than standard Class A SMC by the mandrel bend test. Surface quality is comparable to standard Class A SMC, but the density is 1.55 g/cc vs. the typical 1.9 g/cc. Also new are two toughened, structural low-density SMC systems. Arotran 760 is one with 1.2 g/cc density, utilizing hollow microspheres. Arotran 740 achieves 1.3 g/cc without microspheres, using instead a combination of nano-clay and conventional filler.
Ashland Specialty Chemical Co.
900 Wilshire #110 Troy, MI 48084-1600
Phone (248) 244-9120 Fax (248) 244-8756