Urea flow control agents for urethane paint prepared by reaction of an isocyanate-terminated prepolymer and an ethanolamine

摘要

Urethane-urea flow control agents are synthesized by a two-step process. First, an isocyanate-terminated urethane prepolymer is prepared by reacting a polyether polyol with a stoichiometric excess of a saturated cyclic aliphatic polyisocyanate. These isocyanate-terminated prepolymers are then modified by reaction with an ethanolamine to form urea endcapped flow control agents having number average molecular weight of between 1000 and 4000. These urea endcapped flow control agents can be blended with any urethane paint system and be compatible in structure. They have shown specifically superior compatibility with melamine cured high solids urethane paint systems. When blended with pigmented urethane paint at relatively small amounts, these flow control agents greatly reduce sagging while maintaining excellent leveling and viscosity properties of the paint.