Rubber Field Info

Rubber Field Info

N-Nitrosamines and Accelerators

There is concern growing with the presence of nitrosamines in rubber articles. One source from the decomposition products of certain accelerators. The suspected nature of these materials centers on the carcinogenic concern. Unsafe derivatives of nitrosamines derive from accelerators containing secondary amines. The most commonly used accelerators that fall into this category are listed in figure:



In response to concerns about the potential carcinogenicity of certain nitrosamines, manufacturers in the rubber chemical industry have been actively working on developing alternative accelerators that offer equivalent curing characteristics while ensuring safety in relation to nitrosamine formation.

The alternatives gaining commercial importance include TBSI, TBzTD, and CLD. TBSI, not only improves resistance to reversion compared to the corresponding sulphenamide but also demonstrates excellent storage stability. Sulphenamides are prone to hydrolysis, which is a significant issue in high-temperature and high-humidity environments.

TBSI is frequently used as a substitute for MOR especially in steel cord skim stocks.

TBzTD, has the capability of producing nitrosamines; however, these nitrosamines are considered non-carcinogenic. With minor modifications, TBzTD can serve as a replacement for TMTD. It is advisable to use TBzTD at higher levels compared to TMTD to account for its higher molecular weight. Additionally, an increase in sulfur content is recommended.

CLD has emerged as a promising alternative to DTDM. This product does not generate nitrosamines. Recently, thiuram derivatives of disobutyl amine, namely tetraisobutylthiuram disulfide (TiBTD) and tetraisobutylthiuram monosulfide (TiBTM), have been introduced as potential substitutes for TMTD and TMTM, respectively.

While N-nitroso di-isobutylamine is considered carcinogenic, it is reported to be safer than the nitrosamines derived from TMTD and TMTM.


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