To obtain a curing agent which has a reduced risk of ignition, etc., and cures an epoxy resin at an increased curing rate by compounding a hydrazine compound or its salt with water.
This curing agent is prepared by compounding 1 mol of a hydrazine compound of the formula: R1R2NNH2 or its salt with 0.3-2 mol, preferably 0.6-1.2 mol, of water. An epoxy resin in an amount of 100 pts.wt. is compounded with the curing agent in an equivalent ratio of epoxy groups to amino groups of 0.2-2.0, preferably 0.3-0.7, and if necessary 20-160 pts.wt., preferably 50-120 pts.wt., filler and reinforcement and additives such as an inorganic pigment, an organic pigment, a viscosity modifier, a levelling agent, an antifoaming agent, a coupling agent, a plasticizer, a diluent, a flame retardant, and an organic solvent and then is cured by heating to 40-120°C. In the formula, R1 is 1-4C linear or branched alkyl, phenyl or pyridyl; and R2 is H or 1-4C linear or branched alkyl.
TOMOTAKI YOSHIHISA
KITAJIMA TAKASHI
NABESHIMA AKIHIRO
Next Patent: POLYAMIDEIMIDE RESIN COMPOSITION AND COATING FILM- FORMING MATERIAL