The invention relates to an aqueous blocked
isocyanate curing agent, a preparation method therefor and an aqueous
coating material. The aqueous blocked
isocyanate curing agent comprises the followingraw materials: a polyisocyanate
trimer, methoxy
polyethylene glycol, polyether
diol, a blocking agent, a cosolvent,
alkali metal alkoxide and a neutralizer, wherein the polyisocyanate is at least oneselected from an aliphatic polyisocyanate
trimer and an aromatic polyisocyanate
trimer, the methoxy
polyethylene glycol is one selected from polyglycol
ether monoalcohols with the molecular weight of300 to 2,000, and the polyether
diol has the molecular weight of 120 to 1,000. The aqueous blocked
isocyanate curing agent can react with resin with active groups such as amino resin and
polyester resin in a
coating formula, a large number of
soft segment structures are introduced into a
coating film, the energy release of the coating film during stone
impact stressing can be retarded, and then, the stone
impact resistance of the coating film is improved, so that the coating film can have stone
impact resistance under the condition of low film thickness.