2,2,4-TRIMETHYL-1,2-DIHYDROQUINOLINE (TMQ) is a widely used antioxidant which provides very good protection vs. heat and oxygen aging.  Used extensively in the tire and non-tire rubber compounding markets, this material is effective in EPR/EPDM, NBR, polybutadiene, polyisoprene, SBR as well as natural rubber formulations.  TMQ does cause slight staining and discoloration.