Improved Adhesion of EPDM Sulfur Vulcanizates to RFL-Treated Fabrics
Abstract EPDM stocks containing 5-norbornene-2,3-dicarboxylic anhydride and cobalt naphthenate, when sulfur vulcanized onto RFL-treated fabrics, show a significant increase in peel adhesion properties. EPDM's containing ENB, as the termonomer, have been found to give the best results. The accelerator is an important part of the total adhesion system. Only the slower curing types are applicable, such as sulfenamides and thiazoles. Both soluble and insoluble sulfur yield equivalent adhesion properties, but the insoluble form has the advantage of producing a higher modulus stock. This adhesion system is applicable to only RFL-treated fabrics in which the latex is a styrene-butadiene-vinyl pyridine type. Reduction of compounded stock cost is possible by increased filler loadings or by the use of a skim coat technique, while still providing improved adhesion properties. Variations in both carbon black and oil levels produce corresponding changes in modulus development and curing time. These properties can be used to predict adhesion results.