1-k and 2-k PVDF hybrid dispersions for protective coating system topcoats

 
Aqueous hybrid dispersions of poly(vinylidene fluoride) (PVDF) and acrylic resins offer a way to achieve highly weatherable topcoats while meeting increasingly stringent VOC requirements. This paper describes new studies to evaluate several PVDF hybrid binders in 1-k and 2-k protective topcoat formulations, against two North American standards: SSPC Paint 36 for solventborne 2-k acrylic-urethane topcoats, and the new (2020) SSPC Paint 47 standard for fluoropolymer topcoats. The 2-k PVDF hybrid topcoats in particular, with standard urethane crosslinking, show chemical and abrasion resistance properties comparable to commercial 2-k acrylic-urethane coatings; and in cyclic corrosion tests of full 2-coat and 3-coat systems using epoxy primers, the performance with these waterborne topcoats is often comparable to systems with commercial solvent-based topcoats. Meanwhile both the 1-k and 2-k hybrid topcoats also demonstrate excellent gloss and color retention in both natural (Florida) and accelerated weathering testing, similar to the highest performing fluoropolymer architectural finishes.