Method for powder coatings
AssigneeBASF SE
InventorsPeter D. Clark, Cynthia A. Stants, Richard J. Foukes
Life of this patent
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Abstract
The present invention relates to a thermoset powder coating composition and method of application. The coating includes a copolymer having a reactive functionality selected from the group consisting of epoxy, carboxy, and hydroxy functionalities and mixtures thereof, a suitable crosslinking agent capable of reaction with the reactive functionality on the copolymer, and an aliphatic or aromatic crystalline, hydroxyl containing compound having a melting point of between 30.degree. C. and 150.degree. C. and a flow control agent. The powder coating is a pigmented or clear coat powder composition applied over a primer layer.
Claims22
A method of coating a substrate with a thermoset powder coating composition comprising the steps of
- I) electrodepositing a primer layer on the surface of a metal substrate and
- II) applying over the previously applied electrodeposited primer layer, a layer of thermosetting powder coating composition including
- a) a film-forming resinous binder including
- i) a copolymer selected from the group consisting of epoxy, polyester, and acrylic copolymers having a reactive functionality selected from the group consisting of epoxy, carboxy, and hydroxy functionalities and mixtures thereof and
- ii) a crosslinking agent capable of reacting with the reactive functionality on the copolymer selected from the group consisting of aminoplasts, blocked aliphatic diisocyanates and blocked aromatic diisocyanates, polycarboxylic acids, acid anhydrides, dicyandiamide and its derivatives, polyphenols, polyamines, glycol urils, and mixtures thereof,
- b) a first flow control agent which is an aliphatic or aromatic crystalline hydroxyl containing compound having a melting point between 30.degree. C. and 150.degree. C., and
- c) a second flow control agent, different from the first flow control agent and
- III) curing both the primer layer and the thermosetting powder coating layer, by baking at a temperature above the melting point of the first flow control agent.
A method of coating a substrate with a thermoset powder comprising
- A) applying to a substrate a layer of a thermosetting powder coating composition including
- a) a film-forming resinous binder including
- i) a copolymer selected from the group consisting of epoxy, polyester, and acrylic copolymers having a reactive functionality selected from the group consisting of epoxy, carboxy, and hydroxy functionalities and mixtures thereof and
- ii) a crosslinking agent selected from the group consisting of aminoplasts, blocked aliphatic diisocyanates and blocked aromatic diisocyanates, polycarboxylic acids, acid anhydrides, dicyandiamide and its derivatives, polyphenols, polyamines, glycol urils, and mixtures thereof,
- b) a first flow control agent which is an aliphatic or aromatic crystalline hydroxyl containing compound having a melting point between 30.degree. C. and 150.degree. C., and
- c) a second flow control agent, different from the first flow control agent and
- III) curing both the powder coating layer by baking, at a temperature above the melting point of the first flow control agent.
A method for improving flow and leveling of a powder coating composition comprising
- A) forming a mixture by combining
- a) a film-forming resinous binder including
- i) a copolymer selected from the group consisting of epoxy, polyester, and acrylic copolymers, having a reactive functionality selected from the group consisting of epoxy, carboxy, and hydroxy and functionalities and mixtures thereof and
- ii) a crosslinking agent selected from the group consisting of aminoplasts, blocked aliphatic diisocyanates and blocked aromatic diisocyanates, polycarboxylic acids, acid anhydrides, dicyandiamide and its derivatives, polyphenols, polyamines, glycol urils, and mixtures thereof,
- b) a first flow control agent which is an aliphatic or aromatic crystalline hydroxyl containing compound having a melting point between 30.degree. C. and 150.degree. C., and
- c) a second flow control agent, different from the first flow control agent;
- B) extruding the mixture;
- C) pulverizing the extrudate to form a particulate blend of the thermoset powder coating composition;
- D) applying the powder coating composition to a substrate and
- E) curing the coating composition by baking at temperatures above the melting point of the first flow control agent.
Dependencies are inferred from the claim text.