Curing of cyanates with primary amines

The reaction of 4-tert-butyl phenylcyanate and aniline was analysed with th e help of HPLC, MALDI-TOF and FT-IR. It was found that the main reaction pr oducts are aryloxy- and arylamino-substituted triazines. A number of side p roducts were identified, which consist of triazine-, isourea-, guanidine- a nd cyanamide-structural elements. Three basic types of reactions are propos ed: (i) stepwise addition of amino- and cyanate- or isourea- groups to form isourea- and guanidine-chains, (ii) ring closure to form aryloxy and aryla mino substituted triazines and (iii) formation of cyanamide structures by a bstraction of phenols from isoureas or amines from guanidines. The curing r eaction of the liquid difuctional cyanate Primaset LeCy with several difunc tional amines was characterized by DSC. All amines accelerate the curing pr ocess, where a large range of reactivities for the at least two-stage react ion was detected. Furthermore, glass transition temperatures of cured cyana te-amine copolymers above 200 degreesC were measured by DMA. Although the t hermal behaviour is slightly worse than that of neat polycyanurates, high p erformance thermosets with easy and adjustable processing are obtained that are attractive for use as adhesives, casting or laminating resins.