Low temperature curable melamine containing coating composition and the use thereof
View Patent ↗The present invention is directed to a melamine containing coating composition curable at ambient temperatures and suitable for coating plastic substrates. The present invention is also directed to a process for coating plastic substrates with a melamine containing coating composition curable at ambient temperatures.
1. A process for producing a coating on a substrate, said process comprising the steps of:
(A) mixing components of a coating composition to form a pot mix, wherein said coating composition consists of:
i) a crosslinkable component consisting of 15 to 99 weight percent of total solid weight of the crosslinkable component a polyester having hydroxyl crosslinkable groups and a weight average molecular weight in a range of from 1500 to 100,000, and 1 to 35 weight percent of total solid weight of the crosslinkable component a melamine having crosslinkable groups selected from an —NH group, a hydroxyl group, or a combination thereof; and
ii) a crosslinking component consisting of a polyisocyanate compound having two or more isocyanate groups that react with the crosslinkable groups at temperatures in a range of from 40° F. (4° C.) to 200° F. (93° C.);
iii) one or more pigments or effect pigments; and
iv) one or more additives selected from conductive additives, viscosity adjuster, catalyst, one or more solvents, or a combination thereof;
wherein said coating composition is formulated as a primer, or a color matched primer;
(B) applying the pot mix over the substrate to form a layer; and
(C) curing the layer on the substrate to form said coating.
2. The process of claim 1 , wherein the crosslinkable component consists of 15 to 99 weight percent of total solid weight of the crosslinkable component the polyester having hydroxyl crosslinkable groups and a weight average molecular weight in a range of from 1500 to 100,000, and 1 to 15 weight percent of total solid weight of the crosslinkable component the melamine having crosslinkable groups selected from an —NH group, a hydroxyl group, or a combination thereof.
3. The process of claim 1 , wherein in the step c) the layer is cured at temperatures in a range of from 40° F. (4° C.) to 200° F. (93° C.).
4. The process of claim 3 , wherein the layer is cured at temperatures in a range of from 50° F. (10° C.) to 150° F. (66° C.).
5. The process of claim 3 , wherein the layer is cured at temperatures in a range of from 65° F. (18° C.) to 122° F. (50° C.).
6. The process of claim 1 , wherein the polyisocyanate compound is a diisocyanate, a diisocyanate trimer, a triisocyanate, a triisocyanate trimer, or a combination thereof.
7. The process of claim 1 , wherein the melamine is selected from monomeric melamine, alkylated melamine, polymeric melamine-formaldehyde resin, alkylated polymeric melamine-formaldehyde resin, or a combination thereof.
8. The process of claim 1 , wherein the substrate is of metal, plastic, or composite plastic materials.
9. The process of claim 1 , wherein the substrate is of plastic materials.
10. The process of claim 1 , wherein the substrate is an automotive vehicle, or an automotive part.
11. The process of claim 1 , wherein the substrate is an electronic device, or an electronic device part.
12. The process of claim 1 wherein said coating composition is an automotive OEM (original equipment manufacturing) or refinish primer.