Coating compositions, dielectric coatings formed therefrom, and methods of preparing dielectric coatings

A method of forming a dielectric coating comprising:

• a) applying a powder coating composition over at least a portion of a substrate, the powder coating composition comprising:
• i) an epoxy functional polymer comprising an amount within a range of from 30 to 50 weight % of the powder coating composition, based on the total resin solids weight of the powder coating composition, wherein the epoxy functional polymer is a diglycidyl ether of Bisphenol A;
• ii) a poly-carboxylic acid functional polyester polymer reactive with the epoxy functional polymer and which comprises an acid value of less than 100 mg KOH/g;
• and
• iii) a poly-carboxylic acid functional (meth)acrylate polymer reactive with the epoxy functional polymer,
• wherein, if a colorant is present, the powder coating composition comprises 35 weight % or less of the colorant, based on the total solids weight of the coating composition, and
• wherein a weight ratio of the poly-carboxylic acid functional polyester to the poly-carboxylic acid functional (meth)acrylate polymer is 1:1 or greater;
• and
• b) curing the powder coating composition to form a coating,
• wherein the coating has a dielectric strength of greater than 2.5 kV at a dry film thickness of less than 8 mils.

A powder coating composition for preparing a dielectric coating comprising:

• a) an epoxy functional polymer;
• b) a poly-carboxylic acid functional polyester polymer reactive with the epoxy functional polymer and which comprises an acid value of less than 100 mg KOH/g;
• and
• c) a poly-carboxylic acid functional (meth)acrylate polymer reactive with the epoxy functional polymer,
• wherein, if a colorant is present, the powder coating composition comprises 35 weight % or less of the colorant, based on the total solids weight of the coating composition,
• wherein a weight ratio of the poly-carboxylic acid functional polyester to the poly-carboxylic acid functional (meth)acrylate polymer is 1:1 or greater,
• wherein the powder coating composition comprises 30 to 50 weight % of the epoxy functional polymer and 30 to 50 weight % of the poly-carboxylic acid functional polyester polymer, based on the total resin solids weight of the powder coating composition, and
• wherein (i) the coating composition further comprises d) an isocyanate functional crosslinker reactive with a hydroxyl functional reaction product obtained from the epoxy functional polymer, poly-carboxylic acid functional polyester polymer, and poly-carboxylic acid functional (meth)acrylate polymer and/or (ii) a coating formed from the powder coating composition has a dielectric strength of greater than 2.5 kV at a dry film thickness of less than 8 mils.