MX9603599A - Process to stop a polymerization reaction by n-nitroamines non-precursor agents. - Google Patents

Abstract

The present invention refers to a process to stop polymerization reactions, which are performed in emulsion or in aqueous medium, by N-nitroamines non-precursor agents. Among typical monomers or monomer mixtures to manufacture synthetic rubbers which can be employed in the polymerization process there are included, for instance, dienes, which can be alternatively mixed with mono-olefins capable to produce copolymerization. The monomers, which polymerization is stopped by this process, are: conjugated and vinyl aromatic dienes; it has been determined that nitroamines are carcinogenic compounds, due to which it is an object of the claimed process to prevent formation of these compounds or of those which can generate them during said polymerization eactions.Polymerization reactions were carried out comparing the behavior of several stopping agents commonly utilized in this industry, with the behavior of new stopping agents, assessing the presence of N-nitroamine compounds, and properties of the obtained rubbers, which were among others: Mooney viscosity, tensile strength and elongation. According to the obtained results, it was determined that a process for stopping a polymerization reaction which comprises contacting a polymerizable composition with a stopping agent, i.e., a benzothiazole derivative, which can have as a substitute a higher or lower alkyl of straight or branched chain, and an alkali metal or ammonium, does not generate N-nitroamine precursor agents, and maintains the properties of synthetic rubber produced from the aforementioned reactions.