Chain-extendable crosslinkable urethane modified polyhydroxy oligomers and coating composition comprising same
AssigneeFord Motor Company
InventorsJoseph W. Holubka, Ray A. Dickie
Life of this patent
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Abstract
High solids, solvent-based resin composition comprises novel chain-extendable, crosslinkable urethane modified polyhydroxy oligomers, crosslinking agent and, preferably, catalyst(s). The composition cures at elevated temperature to provide a coating on a substrate, such as steel, which is highly resistant to corrosion, humidity and solvents and provides corrosion protection for the substrate. The novel oligomers can be the reaction product of a polyol with a half-blocked diisocyanate, wherein said polyol comprises three or more hydroxy, and the half-blocked diisocyanate comprises the reaction product of an organic diisocyanate with approximately one molar equivalent of a monofunctional blocking agent.
Claims19
A solvent-based resin composition comprising:
- A. chain-extendable crosslinkable urethane modified polyhydroxy oligomer containing no ester linkages and bearing three or more hydroxyl groups and a single blocked isocyanate group, comprising the reaction product of a polyol with a half-blocked diisocyanate, wherein said polyol comprises the reaction product of a diepoxide with a diol and bears four or more hydroxyl groups, and said half-blocked diisocyanate comprises the reaction product of an organic diisocyanate with monofunctional blocking agent;
- B. crosslinking agent reactive with hydroxy functionality and substantially unreactive with isocyanate functionality;
- and
- C. organic solvent.
A solvent-based resin composition comprising:
- A. a urethane modified polyhydroxy oligomer of molecular weight about 300 to 1100 containing no ester linkages and bearing three or more hydroxyl groups and a single blocked isocyanate group, comprising the reaction product of a polyol with a half-blocked diisocyanate, wherein said polyol bears four or more hydroxy groups and comprises the reaction product of an epoxy resin having molecular weight of about 100 to 600 and bearing two epoxy functionality, with alkanediol of two to twenty carbons bearing two terminal hydroxyl groups, and wherein said half-blocked diisocyanate comprises the reaction product of organic diisocyanate selected from the group consisting of toluene diisocyanate, isophorone diisocyanate and a mixture of them, with monofunctional blocking agent selected from the group consisting of alcohol, amide, phenol and a mixture of any of them, said oligomer having an unblocking temperature between about 100.degree. C. and about 190.degree. C.;
- B. crosslinking agent reactive with hydroxy functionality of said oligomer and substantially unreactive with free isocyanate functionality, selected from the group consisting of polyalkyl ethers of polymethylol melamines, said crosslinking agent and said oligomer being present in a weight ratio of about 1:1 to about 1:5, respectively;
- and
- C. organic solvent.
A method of making a corrosion, humidity and solvent resistant coating on a substrate, which method comprises applying to said substrate a solvent-based thermosetting coating composition comprising:
- A. a chain-extendable, crosslinkable urethane modified polyhydroxy oligomer containing no ester linkages and bearing three or more hydroxyl groups and a single blocked isocyanate group, comprising the reaction product of a polyol with a half-blocked diisocyanate, wherein said polyol bears four or more hydroxyl groups, and the half-blocked diisocyanate comprises the reaction product of an organic diisocyanate with monofunctional blocking agent, wherein said monofunctional blocking agent has a de-blocking temperature of between about 100.degree. C. and about 190.degree. C.;
- B. crosslinking agent reactive with said hydroxy functionality of said oligomer and substantially unreactive with said isocyanate functionality;
- and
- C. organic solvent;
- and heating said composition to at least about 100.degree. C. for a period of sufficient to cure said composition.
Dependencies are inferred from the claim text.