hydrazides of the formula or n -- ch . sub . 2 ch . sub . 2 conhnh . sub . 2 ). sub . 3 . sub . 2 n -- r -- n -- ch . sub . 2 ch . sub . 2 conhnh 2 ) 2 are good latent curing agents for epoxy resin , in the formula r is divalent hydrocarbon residue having 2 - 24 carbon atoms . the curing agents are useful in formulating novel storable one - package , heat - curable epoxy resin - based compositions .