Improvement in epoxy adhesives by introducing thiirane groups Investigation of reaction mechanism based on the model reaction

摘要

The ring opening reactions of phenyl glycidyl ether (PGE) and/or phenoxymethylthiirane (PT) and primary amines were investigated. Aniline, cyclohexylamine and n-octylamine were used as primary amines. The initial reaction rate of PT with aniline was larger than that of PGE with aniline, but PT did not react quantitatively due to existence of an equlibrium reaction in the former system. The reaction of PGE with aniline proceeded via addition and produced the 2:1 adduct as a final product, whereas addition and oligomerization reactions occurred competitively in the reation of PT with aniline. The initial reaction of PGE was accelerated in the presence of PT and vice versa, and PT reacted quantitatively. These results indicated that the reaction of PGE was accelerated by thiolate anion and that the equilibrium reaction was retarded by PGE. The reaction behaviors of three-membered rings with other primary amines were similar to those with aniline. The improvement in the curing rate of epoxy adhesives by introducing thiirane groups could be explained in terms of the synergistic effect on enhancement in ring-opening reactivities of three-membered rings.