New Bifunctional Stabilization System for Hot Melt Adhesives, 1993 Hot Melt Symposium Proceedings

Dr. Neal J. Earhart

Dr. Douglas Horsey

Hot Melt Adhesives (HMA) are generally produced by the compounding of several components: polymers, tackifiers, and waxes or oils.

Due to their high compounding, storage, and application temperatures, hot melt adhesive formulations are extremely susceptible to thermal oxidation and degradation. Degradation of the overall formulation or an individual component can greatly affect the performance of a HMA. In order to inhibit thermooxidation, antioxidants are included in the formulation.

Antioxidants are classified by their mechanism of oxidation inhibition; chain terminating primary antioxidants and hydroperoxide decomposing secondary antioxidants. A synergistic effect is often observed when a primary and secondary antioxidant are used in combination.

This paper discusses a new bifunctional antioxidant system which has shown excellent performance in hydrocarbon tackifier based HMA formulations. This new antioxidant system combines a hindered phenol primary antioxidant with a hydrolytically stable phosphite secondary antioxidant. The level of performance, in terms of color and physical property control, attained with this bifunctional system cannot be achieved with conventional antioxidant systems.