Adipic Dihydrazide (ADH)

Adipic Dihydrazide (ADH) is a bifunctional latent curing agent for epoxy resins, providing excellent latency at ambient temperature with activation above 120°C. ADH contains two active hydrazide groups (–NH–NH2) per molecule, each capable of ring-opening epoxy groups, with an equivalent weight of approximately 87 g/eq (based on –NH2 groups). ADH produces epoxy cured systems with notably high flexibility and toughness compared to amine-cured counterparts at similar crosslink density, because the hydrazone linkages formed during cure are inherently more flexible than conventional amine-epoxy bonds. ADH is particularly useful in waterborne epoxy systems, where its water solubility allows formulation of stable 1K or 2K aqueous systems without phase separation. It is also used in one-component adhesives and coatings where room-temperature latency is combined with moderate-temperature cure (120–150°C). Dosage is approximately 10–15 phr for standard BPA epoxy. ADH is a white, water-soluble powder with good stability at ambient conditions. Unlike aromatic amines or isocyanates, ADH has a relatively favorable toxicological profile, with no carcinogen classification, making it preferred in applications requiring lower occupational hazard risk.