Problems of resorcin elimination from adhesive systems for steel cords

Urethanes of various lengths of alkyl chain (Table 1) have been synthesized and used, together with acrylamide, for melamine-formaldehyde resins modification (Table 2). Melamine-formaldehyde resin of higher content of methylene groups (M-CH 2 ) (Table 2) was also elaborated. The resins, spread on calcium silicate, were used as the systems improving the adhesion of rubber to brass plated steel cords with the aim to eliminate toxic resorcin resins from such systems. The results of rheometric measurements of rubber blends containing the resins discussed as well as the results of investigations of strength properties of vulcanizates obtained (Table 3) were presented. The effects of ageing conditions and the type of melamine resin in the blend on the strength of rubber-brass plated steel cord joint were characterized. From the point of view of all the features investigated, the optimal appeared to be the resin modified with butyl urethane or acrylamide. Although M-CH 2 resin showed better strength properties but needed much longer time of vulcanization.