The invention discloses a
polyurethane curing agent compounded by
diphenylmethane diisocyanate and hydroxyl compounds, which comprises the following raw materials in parts by weight: 28 parts to 33 parts of diphenyl-
methane-diisocyanate (MDI)
monomer, 1.5 parts to 2 parts of
trimethylolpropane, 0.5 part to 1.5 parts of
propanediol, 22 parts to 26 parts of hydroxyl
polymer compound, 0.5 part to 1 part of butyl cellosolve, 0.05 part to 0.1 part of
dibutyltin dilaurate, 6 parts to 9 parts of acetic
ether, 6 parts to 9 parts of
butyl acetate, 8 parts to 12 parts of dimethylbenzene and 8 parts to 12 parts of methylbenzene. The invention has the advantages that free MDI is low, and the
polyurethane curing agent has high stability when being stored at high and low temperature and does not turn white in high-wet weather; NCO in the curing agent is high, and when the
polyurethane curing agent is in cross-linking reaction with paint components containing the hydroxyl group, the reaction activity and the construction activation period can be met simultaneously, and the harness of paint films is higher; and the polyurethane curing agent can form into
coating films of different characteristicsafter normal temperature copolymerization by matching with the paint components containing the hydroxyl group. The invention has very excellent use characteristic and wide application fields.