Abstract
Direct adhesions of pre-cured rubber vulcanizates (EPDM or SBR) with uncured rubber compounds (SBR or EPDM) through vulcanization were carried out and their adhesive strength of the obtained samples were measured. The effect of the process oils on the adhesive strength between pre-cured EPDM and uncured SBR has been investigated in regard to several kind of process oils and their loadings in both rubbers. The adhesive strength among the two rubber components compounded with the aromatic process oil in all oils used here showed the highest strength of the adhesion. It was also shown that the strength of the adhesion increased with increasing the aromatic oil loading in the pre-cured EPDM and with decreasing that in the uncured SBR compound before the adhesion through vulcanization.
On the other hand, the adhesion of the pre-cured SBR with the uncured EPDM compound through vulcanization was not improved by compounding the various oils and by varying the oil loading. To improve the adhesion strength in such a case, the compounding of an adhesion promotor such as the system of the resorcinols and hexamethylene tetramine which are commercially available was found to be useful. Especially, an excellent adhesive strength is obtainable by compounding the adhesive promotor with specified accelerators to uncured EPDM compound.
