The invention discloses a high-functionality hydroxyl-terminated
polyurethane aqueous dispersion as well as a preparation method and application thereof. The preparation method comprises the following steps: adding aliphatic diisocyanate, polyvalent
alcohol, a hydrophilic chain-extending agent and a catalyst into a reaction kettle; carrying out temperature rise reaction under the protection of
nitrogen gas and cooling when the NCO percent of a
system reaches a theoretical value; dropwise adding an
acetone solution of a dihydric
alcohol chain-extending agent and a crosslinking agent, continuously reacting and diluting with
acetone when the NCO percent of the
system reaches the theoretical value; cooling, and adding
triethylamine for neutralizing; adding water for dispersing, and adding alcamines compounds for terminating; finally, carrying out post chain extending by using ethidene
diamine to obtain the hydroxyl-terminated
polyurethane aqueous dispersion. According to the high-functionality hydroxyl-terminated
polyurethane aqueous dispersion disclosed by the invention, an alcamines terminating agent with polyhydroxy functionality is adopted, and a polyhydroxy functional group is introduced on a polyurethane
chain segment by a terminating reaction of an amine group and an NCO group; the obtained aqueous dispersion has the advantages of high
solid content,
small particle size and
stable storage; a two-component waterborne
polyurethane coating prepared by the high-functionality hydroxyl-terminated polyurethane terminating dispersion has the characteristics of high
drying speed of the
coating, excellent medium resistance and environment friendliness of a product.