Efficient and Semiefficient Vulcanization Systems Employing 2-(Morpholinodithio)-Benzothiazole Generated in Situ
Abstract The MBTS-N-(morpholinothio)phthalimide vulcanization system has been found to be effective in producing heat resistant semi-EV and EV cures in a variety of representative rubbers. When used as a direct replacement on a molar basis for 2-(morpholinodithio)benzothiazole (MDB), improvements in processing safety were found in all cases studied. In this respect it is most effective in NR, SBR, and NBR. The experimental system also generally gave slower-curing stocks. The heat resistance of the experimental stocks was found to be equal to or better than that of the MDB control stocks. Substantial improvements in heat resistance for both SBR and IIR unexpectedly resulted from the use of the MBTS—imide system. This result suggests that the nature of the crosslinks formed by the two vulcanization systems are to some extent different in these two elastomers. This, in turn, may reflect upon the mechanisms of crosslink formation.