Rohm and Haas Company

Akzo Nobel Coatings International B.v.

Sabine Molitor-Limberg

Andrew T Daly

The present invention provides coating powders that enable improved filiform corrosion resistance in clear or tinted clear coating comprising an epoxy functional acrylic copolymer component having a Tof from 40&#xb0; C. to 90&#xb0; C. and chosen from a copolymer or copolymer mixture that comprises, based on the total weight of copolymerized monomers in the epoxy functional acrylic copolymer component, i) from 10 to 40 wt. % of one or more epoxy functional unsaturated monomer, e.g. glycidyl (meth)acrylate; ii) from 2.0 wt. % to 13 wt. %, preferably 12 wt. % or less, or, more preferably, 6 wt. % or less, of one or more hydrophobic acrylic monomer that has a mass solubility in water of 3.5 g/L or less and which would itself form a homopolymer having a glass transition temperature (T) of 50&#xb0; C. to 175&#xb0; C., e.g. a bicycloalkyl(meth)acrylate, and iii) the remainder of one or more nonionic comonomer that is not a hydrophobic acrylic monomer ii), e.g. methyl methacrylate; one or more crosslinker for the thermosetting acrylic copolymer; and, optionally, one or more adhesion promoter, e.g. epoxy resin, a light stabilizer, an ultraviolet (UV) absorber, and/or a hydrophobic submicron particle.

Epoxy functional acrylic coating powders and powder coatings therefrom having improved filiform corrosion resistance

The present invention provides coating powder compositions for making filiform corrosion resistant coatings, the compositions comprising particles or agglomerates which include, intimately mixed, each of one or more thermosetting acrylic copolymer, one or more crosslinker for the acrylic copolymer and one or more hydrophobic submicron particle additive, wherein the hydrophobic submicron particle additive comprises from 0.01 to 1.5 wt. %, based on the total weight of the coating powder. The hydrophobic submicron particle additive comprises a submicron inorganic oxide, e.g. fume silica or a metal oxide, and one or more organosilicon compound, e.g. polydimethylsiloxane. In addition, the invention provides filiform corrosion resistant clear coat or tinted clear coat powder coatings on metal, e.g. aluminum wheels or forged alloy substrates.

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Eslohe, Germany

Sabine Molitor-Limberg