Adhesion Effects in Bonding Rubber to Metal by Leukonat Adhesive

Abstract

1. In bonding of rubber to metal by Leukonat adhesive, the type of filler present in the rubber has a very great influence on the rubber-metal bond strength. 2. Active fillers of the gas channel black type in the rubber mixture increase the interaction of the rubber with the adhesive film. 3. Inactive fillers of the thermal black type have little influence on the interaction of the rubber with the adhesive film. 4. The results of the experiments suggest that Leukonat interacts chemically with active fillers present in the rubber during the bonding process. 5. The following empirical rule is formulated: high rubber-metal bond strength is obtained if the interaction of the adhesive film with the rubber is approximately of the same degree as with the metal. This rule is supported by the experimental data. 6. Sandblasting of the metal surface increases the true contact area by a factor of 1.5\2-2, while the bond strength is increased 20 to 100 times; this indicates that qualitative changes occur in the surface on sandblasting and that the nature of the metal-adhesive interaction is greatly changed in the process. It is difficult to explain this other than on the assumption that the charge of the double layer at the metal-adhesive boundary is increased, and in consequence the work of separation of this layer at the boundary is greater.