Melamine in Automotive Paint

Question:

Our plant is located in South Africa. I am curious about melamine in automobile paint and the way it is being used in the automobile factories.

If the paint work damaged in the automobile factory, can they put polyurethane in the melamine paint to promote curing? E. P.

1. Why is melamine part of the automobile original topcoat paint?
2. Can melamine be part of a refinish paint?

Answer:

Melamine is a heat-reactive resin added to coatings to increase mar resistance and improve weatherability. The “Super Alkyds” (alkyd-melamine) enamels used as automotive topcoats in the 1960s are prime examples of this technology. They were used by the auto makers who applied baking enamels. The newer melamine modified top coats, acrylic-melamine automotive enamels, are noted for their gloss retention. Today, many auto makers apply a color coat/clearcoat system, using a polyurethane clearcoat. There is nothing wrong with alkyd-melamine and acrylic-melamine enamels, they are still excellent topcoats.

As far as refinish enamels, alkyd-melamine and acrylic-melamine top coats can be used, but they must be baked. Most refinishers prefer to use catalyzed and other fast air-drying topcoats, since time is of the essence.

Acrylic-melamine, alkyd-melamine and polyurethanes enamels can be cured by infrared radiation. Although I haven’t tried it, I don’t believe you can just add a polyurethane to an alkyd melamine enamel to promote curing by infrared radiation. There would probably be a compatibility problem or a chemical reactivity problem.