POLYURETHANE DISPERSION BASED COATINGS HAVING ENHANCED REMOVABILITY

摘要

The present invention provides a method for preparing an aqueous polyurethane dispersion comprising a polyurethane polymer, where the method comprises the step of (A) preparing a prepolymer from a reaction mixture comprising: (1) at least one polyisocyanate compound; (2) at least one polyol; and (3) ions of at least one alkali or alkaline earth metal; followed by the step of (B) contacting the prepolymer with a chain extending agent to form the polyurethane polymer. The present invention further provides an aqueous polyurethane dispersion comprising from 30% to 40%, by weight, of solids which comprise the polyurethane polymer and being prepared by the aforesaid method. A coating composition having enhanced removability and which comprises an aqueous polyurethane dispersion prepared according to the aforesaid method is also provided.

主权项

1. A method for preparing an aqueous polyurethane dispersion comprising a polyurethane polymer, said method comprising:
(A) preparing a prepolymer from a reaction mixture comprising:
(1) at least one polyisocyanate compound;(2) at least one polyol;(3) ions of at least one alkali or alkaline earth metal; and(4) optionally, at least one surfactant selected from the group consisting of a hydrophilic compound, an external surfactant, and combinations thereof; and (B) contacting the prepolymer with a chain extending agent to form the polyurethane polymer.