“NITROSAMINE SAFE” THIURAM DISULFIDE

Abstract

ABSTRACT An investigation into the technological performance of a new nitrosamine safe thiuram disulfide, tetraisononylthiuramdisulfide (TINTD), in natural rubber was undertaken. Initially, TINTD was synthesized from di(3,5,5-trimethylhexyl)amine. It was then demonstrated to function as a sulfur donor, a primary accelerator, and as a secondary accelerator when combined with sulfenamides. These investigations found that the long-branched alkyl chain on the nitrogen of TINTD and of its vulcanization breakdown product zinc diisononyldithiocarbamate (ZDNC) makes both chemical species very soluble in the elastomer. This high solubility of TINTD and ZDNC in the rubber makes TINTD highly attractive for use in soluble efficient vulcanization systems. In addition, the nature of the long-branched alkyl chain means that the formation of carcinogenic N-nitrosamine is difficult, and if formed, it is toxicologically much less hazardous in terms of both acute toxicity and metabolic activity. Thus, concerns of accelerator toxicity, irritant dermatitis from thiuram and dithiocarbamate, and type IV allergy may be reduced or totally eliminated. The curing efficiency of various thiuram disulfides was also investigated as a function of alkyl chain length and the degree of chain branching. The cure performance was found to be determined by both chain length and chain branching.