LATENT HARDENER FOR POLYURETHANE COMPOSITIONS AND PROCESS FOR PREPARING THEREOF Russian patent published in 1995 - IPC

FIELD: manufacture of thermosetting polymeric compositions having unlimited stability under standard conditions, which are used for enameling conductors. SUBSTANCE: the process uses a hardener of the general formula: R-[OCONHC₆H₄(CH₃)NHOCOC₆H₄(CH₃) wherein R is a polypropylenetriol having a molecular weight of 365-390. The hardener is prepared by reacting 2,4-toluylene diisocyanate or a mixture of toluylene diisocyanate isomers with tricresol at a molar ratio of 1:1.1-1.2 at 60 C for 1-1.5 hours and subsequently reacting with polyoxypropylene triol at a NCO to OH molar ratio of 1:1 at 60 C for 3-3.5 hours. To manufacture varnish compositions, the product may be supplied either in powder form after cooling to room temperature and grinding or as a solution in a suitable solvent (tricresol, acetate or acetone). EFFECT: improved properties of the latent hardener. 3 cl