Compatibility Improvement between Chlorinated Thermoplastic Rubber and Polychloroprene Adhesive

Abstract

Abstract Traditionally, it has been believed that there is an incompatibility between the chlorinated rubber surface and polychloroprene adhesives resulting in a lack of adhesion. However, in this study it has been shown that a polychloroprene adhesive (PCP30P) produces similar T-peel strength values when using a polyurethane (PU) adhesive in joints produced between a chlorinated thermoplastic SBS rubber and roughened leather. In both cases a cohesive failure mode within the rubber was obtained. This polychloroprene adhesive (PCP30P) contains a thermoreactive phenolic resin in its formulation. The nature of the resin greatly influences the viscoelastic properties of the polychloroprene adhesive. Thus, polychloroprene adhesive with no resin or with resins of a different nature do not produce suitable adhesive joints between the chlorinated rubber and the leather (Terpene phenolic resin (PCP30TP), a glycerol esther colofony resin (PCP30EC) and an aromatic hydrocarbon resin (PCP30AH) were studied). The interactions produced between the chlorinating agent and the adhesive were studied by ATR-IR on solid films of the polychloroprene adhesives and the tackifier resins previously immersed in the chlorinating solution (0.5 and 3 wt% TCI/MEK). All the polychloroprene adhesives were modified by the chlorinating agent, being capable of producing a good interaction with the chlorinated rubber surface at the interface. Therefore, the good performance of the PCP30P adhesive compared with the other polychloroprene adhesives has been ascribed to rheological behavior more similar to the PU adhesive assessed by DMTA. The PCP30P adhesive is the most elastic material among all the considered polychloroprene adhesives. This increased elasticity and better viscoelastic properties are imparted by the thermoreactive phenolic resin in its formulation.