A new series of cyclic 5-membered dithiocarbonates having urethane tether: Application as an adhesion promoter to epoxy-amine curing system

A new series of bifunctional DTC compounds having urethane linkage (DTC-urethanes 1), which can be easily obtained by reaction of DTC-OH with diisocyanate was investigated. Bifunctional DTC-urethanes 1 can be easily synthesized from DTC-OH by the addition reaction of hydroxyl group with diisocyanate. The reaction was effectively promoted by a catalytic amount of dibutyltindilaurate (DBTDL). The resin part comprised of Bis A-DGE and 1 was mixed with PPG-diamine to start the curing reaction. The curable formulation thus prepared was applied as an adhesive to steel-bonding. The formulation was applied between two steel plates and was cured at 50 °C for 24h, and the resulting specimen was subjected to the lap-shear test according to the standard procedure (ASTM D1002). It was observed that the facile synthesis of DTC-urethane based on the highly reliable reaction of DTC-OH with isocyanate gives an opportunity of a wide range of structural design for DTC-carrying molecules.