Abstract: Novel, high solids urethane clearcoat compositions having improved flow characteristics by the incorporation of a flow control system composed of urea thixotrope/acrylic microgel additives. The urea thixotrope constituent is prepared by reacting a polyether polyol with a stoichiometric excess of a saturated cyclic aliphatic polyisocyanate to produce isocyanate-terminated prepolymers. These prepolymers are then modified by reaction with an ethanolamine to form urea end-capped thixotropes which are compatible in structure with any urethane clearcoat system. A combination of one of these urea thixotropes and a polymethyl methacrylate microgel of fine particle size is used effectively to reduce sagging of high solids urethane clearcoat systems. In fact, the combination of the two components produces a synergistic effect which is greater than that expected from any one of the components in the flow control system.

Abstract: Novel, high solids urethane clearcoat compositions having improved flow characteristics by the incorporation of a flow control system composed of urea thixotrope/silica additives. The urea thixotrope constituent is prepared by reacting a polyether polyol with a stoichiometric excess of a saturated cyclic aliphatic polyisocyanate to produce isocyanate-terminated prepolymers. These prepolymers are then modified by reaction with an ethanolamine to form urea endcapped thixotropes which are compatible in structure with any urethane clearcoat system. A combination of one of these urea thixotropes and a finely divided transparent silica is used effectively to reduce sagging of high solids urethane clearcoat systems. In fact, the combination of the two components produces a synergistic effect which is greater than that expected from any one of the components in the flow control system.

Abstract: 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.

Abstract: Waterborne acrylic copolymer-melamine enamels have a long storage life at room temperature and yet are curable at relatively low temperatures when containing suitable sulfamate ester curing agents such as ethyl N,N-dimethylsulfamate.

Abstract: Novel, low viscosity, high solids paint compositions have been created which provide durable, high gloss surface finishes when they are applied to and cured over suitable substrates. The paints are based on urethane binder resins formed by initially reacting a hindered piperidinol ultraviolet stabilizer with a stoichiometric excess of aliphatic polyisocyanate. This reaction product is in turn reacted with a stoichiometric excess of polyether polyols. The paint compositions are cured by crosslinking the urethane binder resins at the unreacted functional hydroxyl groups of the polyol constituents by means of acid catalyzed, melamine formaldehyde crosslinking agents. Cure can generally be fully accomplished in a short time at temperatures below about 250.degree. F. The cured paint has piperidine groups chemically incorporated within its molecular structure to effectively inhibit the degradation of the urethane linkages and the loss of gloss by ultraviolet radiation.