VERBESSERUNGEN AN UND IN BEZUG AUF DIE RÜCKGEWINNUNG VON NATUR- UND SYNTHESEKAUTSCHUKEN

A process of recycling used sulphur-cured elastomeric materials comprising masticating the said elastomeric materials at temperatures below 50 DEG C with a novel chemical mixture which is capable of initiating proton exchange in a controlled manner and thereby open up or delink the vulcanised network of the elastomeric materials. The novel chemical mixture is made from the zinc salt of dimethyldithiocarbamate and mercaptobenzothiazole in the molar ratio in the range of 1:1 to 1:12 dispersed in diols and in the presence of stearic acid, zinc oxide and sulphur. This mixture, which may be termed the 'Delink' when blended with tyre crumbs or any other vulcanised crumbs in concentrations of 6 parts binder per 100 parts of rubber crumbs on a mill effectively delinks the vulcanised network and renders the compound ready for moulding and vulcanisation. The total milling period, which occurs at temperatures below 50 DEG C, takes only 7 to 10 minutes. Alternatively, the binder and tyre crumbs could be first mixed in an intermix and subsequently milled in an open mill. The obtained recycled rubber compounds display satisfactory levels of physical and dynamic characteristics. Such compounds can be directly used in moulded goods or in admixture with fresh compounds in tyres and related areas.