Rhein Chemie’s special chemicals are versatile problem solvers
The dithiophosphates from the Rhenocure line, for example, are used as non-discoloring accelerators for the rapid vulcanization of EPDM and diene rubber. Because dithiophosphates contain no nitrogen components, vulcanization produces no secondary amines that could be converted into carcinogenic nitrosamines. Dithiophosphates are in liquid form, but marketed by Rhein Chemie in silica-bound form. They are easy to handle and can be dispersed in a mixture homogeneously and without residues. Dithiophosphates are also available in polymer-bound form as Rhenogran®.
Rhein Chemie markets a number of vulcanization activators for crosslinking special elastomers. Rhenofit® CF (GE 1890), for instance, is a vulcanization activator for fluoroelastomers (FKM) characterized by low compression set values even at high temperatures. These elastomers result in mixtures that are stable in storage, reliable in processing and offer high degrees of crosslinking. Rhenofit® Na Stearate 80 is used together with Rhenogran® Diuron, or quaternary ammonium salts, as a crosslinking system for chlorocarboxyl polyacrylate rubber grades (ACM). These grades are particularly high crosslinking and generally require no post-vulcanization.
Polymer radicals produced during peroxide vulcanization react with the methacrylate groups in co-agents such as Rhenofit® EDMA/S and Rhenofit® TRIM/S, creating additional, reactive points for crosslinking. The degree of crosslinking in elastomers frequently can be significantly increased in this way, much more so than higher doses of peroxide can achieve. The vulcanizates show in some cases significantly higher hardness, modulus and tensile strength, and improved abrasion.