Abstract: Provided are a modified diphenylmethane diisocyanate (MDI) biuret curing agent and preparation method thereof, the curing agent being prepared by reacting dibasic alcohol, water and MDI in an organic solvent. The preparation method includes the steps of: firstly, using the dibasic alcohol to modify a part of MDI, dividing the metered water into multiple parts, and adding the water by multiple times; after adding the first part of water, reacting firstly under 70-100° C., then heating up to 120-140° C. for reaction; secondly, lowering the temperature to 70-100° C., adding the second part of water; and repeating the above processes until all the metered water is added, to produce the MDI curing agent with partial biuret structure. The curing agent is mainly used as the curing agent of polyurethane coating and adhesive agent, and has a higher NCO percentage and a slower curing speed than that of common MDI prepolymer curing agents.

Abstract: Provided are a modified diphenylmethane diisocyanate (MDI) biuret curing agent and preparation method thereof, the curing agent being prepared by reacting dibasic alcohol, water and MDI in an organic solvent. The preparation method includes the steps of: firstly, using the dibasic alcohol to modify a part of MDI, dividing the metered water into multiple parts, and adding the water by multiple times; after adding the first part of water, reacting firstly under 70-100° C., then heating up to 120-140° C. for reaction; secondly, lowering the temperature to 70-100° C., adding the second part of water; and repeating the above processes until all the metered water is added, to produce the MDI curing agent with partial biuret structure. The curing agent is mainly used as the curing agent of polyurethane coating and adhesive agent, and has a higher NCO percentage and a slower curing speed than that of common MDI prepolymer curing agents.