| abstract |
The invention provides a waterborne blocked hyperbranched polyisocyanate cross-linking agent and a preparation method thereof. The preparation method comprises the steps of enabling an NCO tripolymer to react with N-substituted ethanolamine at low temperature by virtue of the difference of reaction activation energy of isocyanate groups (NCO), an amino group and a hydroxyl group to prepare an AB2-type intermediate containing two NCO groups and one hydroxyl group; and then, carrying out in-situ polymerization, blocking, neutralization and other processes on the AB2-type intermediate under the heating condition to obtain the waterborne blocked hyperbranched polyisocyanate cross-linking agent. Compared with a conventional synthesis process for a hyperbranched polymer, the preparation method has the advantages that a reaction process and a product structure are more easily controlled; in addition, due to the adopted hyperbranched structure of the cross-linking agent, all active groups which can be deblocked are located at the periphery of a high polymer and easily react with resin when cured, so that the curing efficiency is increased. |