Polyisocyanate composition having high emulsifiability and stability, and aqueous coating composition comprising the composition

Abstract

Disclosed is a polyisocyanate composition which comprises: (a) a hydrophilic polyisocyanate comprising at least one base polyisocyanate selected from an aliphatic and/or an alicyclic diisocyanate, and a polyisocyanate derived therefrom, and a nonionic hydrophilic group, bonded to the polyisocyanate, containing therein 5 to 50 repeating ethylene oxide units in terms of the average number of the units, wherein the hydrophilic group is present in an amount of from 2 to 50% by weight, based on the total weight of the base polyisocyanate and the hydrophilic group; and (b) 0.5 to 20% by weight, based on the total weight of components (a) and (b), of a substantially water-free ionic surfactant. The polyisocyanate composition exhibits not only excellent dispersibility in water, but also exhibits high stability in the form of an aqueous dispersion thereof, since a reaction between the terminal isocyanate groups and water is suppressed. Further, a cold crosslinkable, two-pack aqueous urethane coating composition, which comprises an aqueous polyol as a main agent and the polyisocyanate composition as a curing agent, has not only excellent pot life characteristics, but also is capable of forming a coating which has excellent properties, such as excellent water resistance, so that such an aqueous coating composition can be advantageously used as various aqueous paints, adhesives, building materials and sealing materials.

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