Improving the safety of rubber as a food contact material

6 Improving the safety of rubber as a food contact material 

Nitrosamines form as a result of the reaction of nitrosating agents with secondary amines in the rubber. One of the main sources of secondary amines is a number of the accelerators that are used in sulphur-based cure systems, the amines being breakdown products produced as a result of the chemical reactions taking place during vulcanisation. Specific examples of these accelerators, their secondary amine products (i.e. the nitrosatable compounds) and the nitrosamines derived from them, are given in Table 12.7. 

The main approaches that have been taken to ensure that the concentration of nitrosamines (and nitrosatable compounds) in a given rubber is as low as possible are as follows  

Re-compounding the rubber to wholly or partially substitute accelerators that produce secondary amines with those that do not, such as CBS, MBT and MBTS. 

Substitution of carbon black filler (or a significant part of it) with white reinforcing fillers (e.g. silica), as carbon black has also been found to act as a nitrosating agent. 

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