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AssigneeGeneral Motors Corporation
InventorsRobert A. Ottaviani, William T. Short, Donald J. Hart
Estimating the term…
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.
A sprayable high solids urethane clearcoat composition comprising a urethane binder resin, a partially methylolated melamine cross-linking agent, and a flow control system consisting of a urethane-urea polymer and silica particles, said flow control system being added in an amount between 7 to 15 weight percent of said composition to improve the flow properties of the urethane clearcoat, said urethane-urea polymer constituent being a reaction product of an isocyanate-terminated polyether urethane prepolymer and an ethanolamine selected from the group consisting of monoethanolamine, diethanolamine, and triethanolamine.
A sprayable polyurethane clearcoat composition containing at least about 50 weight percent nonvolatile constituents comprising a urethane binder resin being a reaction product of an aliphatic poly-isocyanate and a stoichiometric excess with respect to the polyisocyanate of polyether polyols, a partially methylolated melamine cross-linking agent and an amount between 7 to 15 weight percent of said composition of a flow control system consisting of a combination of a urethane-urea polymer and fine particle size silica, said flow control system reducing sagging of the urethane clearcoat when applied to vertically oriented substrates, said urethane-urea polymer being a reaction product of an isocyanate-terminated prepolymer prepared by the reaction of one or more polyether polyols with an excess of a diisocyanate and an ethanolamine selected from the group consisting of monoethanolamine, diethanolamine, and triethanolamine.
A sprayable polyurethane clearcoat composition containing at least about 50 weight percent nonvolatile constituents which composition produces a durable surface finish when applied to and cured over a suitable substrate, said composition comprising a urethane binder resin being a reaction product of an aliphatic polyisocyanate and a stoichiometric excess with respect to the polyisocyanate of polyether polyols, a partially methylolated melamine cross-linking agent and a flow control system consisting of a combination of a urethane-urea polymer and fine particle size silica in a ratio between 1:3 to 4:1, said flow control system when added in an amount between 7 to 15 weight percent of said clearcoat composition reducing sagging of said clearcoat when applied to vertically oriented substrates without adversely affecting the viscosity and gloss properties, said urethane-urea polymer being a reaction product of an isocyanate-terminated prepolymer prepared by the reaction of one or more polyether polyols with an excess of a diisocyanate and an ethanolamine selected from the group consisting of monoethanolamine, diethanolamine, and triethanolamine.
Dependencies are inferred from the claim text.