SELF-EMULSIFYING POLYISOCYANATE AND WATER-BASED COATING USING THE SAME

摘要

PROBLEM TO BE SOLVED: To provide a self-emulsifying polyisocyanate which affords a water- dispersed polyisocyanate having a sufficient pot life and gives a sufficient crosslining density when used as a curing agent and to provide a water-based coating. SOLUTION: The self-emulsifying polyisocyanate is obtained by reacting a compound (a) comprising a hydrophilic segment and a hydrophobic segment represented by formula: R1-A-B-OH, wherein A is a hydrophilic segment; B is a hydrophobic segment; and R1 is a monovalent organic group with an organic polyisocyanate (b), where the hydrophilic segment is a divalent organic group comprising a recurring unit bearing a hydrophilic polar group and the hydrophobic segment is a divalent organic group other than the hydrophilic segment. The water-based coating comprises this self-emulsifying polyisocyanate. Preferably, in the compound (a), the hydrophilic segment has a number-average mol.wt. of at lezst 300 and the hydrophobic segment has a number-average mol.wt. of at least 300. The organic polyisocyanate (b) is preferably one obtained by isocyanuration of hexamethylene diisocyanate or z urethane-modified product of hexamethylene diisocyanate.