Rubber Chemicals from Cyclic Amines. II Dithioamines and Sulfenamides as Accelerators and Curing Agents

Dithioamines and sulfenamides derived from various cyclic amines were evaluated as accelerators and vulcanizing agents. Structural variations of these compounds are correlated with their scorch delaying properties, accelerating activity and vulcanization efficiency, employing the Mooney Viscometer and the Monsanto Oscillating Disk Rheometer. The relative cure characteristics differed with changes in the basic structure of the compounds, and with the size and type of the cyclic amine moiety. However, the piperidine derivatives consistently showed longer scorch delay and slower mean cure rate than the corresponding derivatives of pyrrolidine, hexamethylenimine or heptamethylenimine. In the case of the thiazolyl sulfenamides, the type of substitution in the thiazolyl group also influenced scorch delay. An empirical relation was observed between the effect of concentration of the thiazolyl sulfenamides on scorch delay and the results of differential thermal analyses of sulfenamide and sulfur blends.