Powder coating with non-crystalline and crystalline epoxy resins and curing agent
AssigneeRohm and Haas Company
InventorsWilliam G. Ruth, Stacy L. Greth, Carryll A. Seelig, Dean A. Schreffler
Life of this patent
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Abstract
Provided are low temperature curing thermosetting epoxy powder coating compositions comprising at least one non-crystalline epoxy resin, at least one crystalline epoxy resin, a curing agent, and a cure catalyst. Coatings made from such powder compositions exhibit a substantial reduction in bubble entrapment, enough to prevent a visible haze from forming in the coating, when cured at low temperatures demanded by brass substrates.
Claims12
A method for obtaining a bubble-free and visible haze-free coating on a substrate susceptible to outgassing and/or degradation upon heating, comprising applying a powder coating composition which comprises a film-forming blend of:
- a) at least one non-crystalline epoxy resin;
- b) at least 5% by weight and no more than 20% by weight, based on the weight of a) plus b), of at least one crystalline epoxy resin;
- and,
- c) a curing agent to facilitate curing of said composition to a thermoset state,
- on a surface of the substrate, and curing the powder coating on the substrate at temperatures below the substrate outgassing and/or degradation temperature until the coating reaches a thermoset state, wherein the coating film resulting on the substrate is without a visible haze.
Dependencies are inferred from the claim text.