Effects of ozone and UV on tire cord adhesion

Ozone exposure of resorcinol‐formaldehyde‐latex (RFL) dipped tire cords reduces adhesion because ozone attacks the double bonds in the butadiene component of the rubber latex in RFL and impairs its cocuring with the solid rubber compound. This mechanism also explains: (a) the ineffectiveness of chemical antiozonants or chloroprene latex as RFL additives, (b) the increased ozone sensitivity of RFL adhesion with progressive curing of RFL dip, and (c) the insensitivity to ozone of adhesion with RF‐EPDM adhesives. A major reduction in the rate of adhesion loss in either ozone (50 pphm, 50% RH) or UV (carbon arc, 4 hr) was demonstrated when small amounts of waxes (3% solids basis) were added to the RFL dip. The waxes protect the RFL adhesive by blooming to the surface of the adhesive treated cord.