Curing of bisphenol A-based liquid epoxy resins with polyamine-2-mercaptobenzothiazole adducts and synthesis of the adducts

Polyaddition of triethylenetetraamine (TETA) to 2-mercaptobenzothiazole (MBT) carried out in the melt at 70-75 degreesC gave novel adducts (TM) which were liquids of low toxicity, low volatility and faint amine-like odor, insensitive to moisture, infusible (< 15 degreesC) and well miscible with epoxy resins (Table 1). When used to cure (at 20-100 degreesC) epoxy resins, the adducts proved to be more reactive than TETA, because of the catalytic effect of the -SH groups in MBT. The TM-cured epoxy resins exhibited satisfactory mechanical properties and good resistance to chemicals, heat and water (Tables 4-6). Crystalline adducts (MM), m.p. 78-84 degreesC, of methylenedianiline (MDA) to MBT were also prepared (Table 2). At 55 degreesC, the pot life of the MM-cured epoxy resin compositions was much shorter than that of the compositions with MDA only. The MM-cured compositions showed better mechanical and thermal properties as compared with those cured with MDA (Table 4). They can be used as adhesives, wet lay-up laminates.