dispersions. Coatings with higher pigment volume
concentration, and containing a coalescent which has
good solvency for PVDF, showed dramatically improved
water-blister resistance and wet adhesion over aged PVDF
finishes. Several mechanisms may be operative in accounting for these results. Improvements in the adhesion
may also be obtained through the use of a variant hybrid
dispersion with lower Tg. This lower Tg version has the
added benefit that it may be formulated at very low VOC
content. Finally, the influence of surface topographic
features and composition of the PVDF finish were also
discussed, and found to play crucial roles in adhesion of
restoration coatings based on PVDF-acrylic hybrids.
ACKNOWLEDGMENTS
We would like to thank Dr. Mehdi Durali for the
synthesis of PVDF-acrylic hybrid emulsions. Also, the
technical help of Dr. Min Zheng, Wayne Skilton, and
Cynthia Hess is greatly appreciated. We would also like
to thank Dr. Gunter Moeller for helping with surface
roughness measurements. Finally, we would like to
thank Jerry Petersheim, new business development
engineer for Kynar® PVDF coatings, for encouraging
studies in this area.
References
( 1) Iezzi, R.A., “Fluoropolymer Coatings for Architectural Applications,”
Modern Fluoropolymers, John Wiley & Sons, p. 271, 1997.
( 2) Iezzi, R.A., Gaboury, S., and Wood, K., “Acrylic Fluoropolymer
Mixtures and Their Use in Coatings,” Prog. Org. Coat., 40, p. 55-
60 (2000).
( 3) Wood, K.A., “Optimizing the Exterior Durability of New
Fluoropolymer Coatings,” Prog. Org. Coat., 43, p. 207-213 (2001).
( 4) Gu, X., Nguyen, T., et al., “Surface and Interface Properties of
PVDF/Acrylic Copolymer Blends Before and After UV Exposure,”
Proc. 80th FSCT Annual Meeting, New Orleans, LA (2002).
( 5) Wood, K., Hedhli, L., and Willcox P.J., “Patterns of Erosion from
Acrylic and Fluoropolymer Coatings in Accelerated and Natural
Weathering Tests,” J. Coat. Technol., 74, No. 924, p. 63-68 (2002).
( 6) Faucheu, J., Wood, K., et al., “Relating Gloss Loss to Topographical
Features of a PVDF Coating,” J. Coat. Technol. Res., 3, No. 1,
p. 29-39 (2006).
( 7) Hinder, S., Lowe, C., and Watts, J., “An XPS and ToF-SIMS Investigation of the Outermost Nanometers of a Poly
(vinylidene di fluoride) Coating,” Prog. Org. Coat., 60, p. 255-
261 (2007) and references therein.
( 8) Funke, W., “Blistering of Paint Films and Filiform Corrosion,”
Prog. Org. Coat., 9, p. 29-46 (1981).
( 9) Hansen, C.M., “New Developments in Corrosion and Blister
Formation in Coatings,” Prog. Org. Coat., 26, p. 113-120 (1995).
( 10) Our unpublished studies of water uptake analysis of unpigmented coatings prepared from PVDF-acrylic hybrid dispersions
have shown that air-dried coatings typically contain 1–2% of
labile species, which are leached out of the coating during the
first cycle of water immersion.
( 11) Asbeck, W.K. and Van Loo, M., Industrial and Engineering
Chemistry, 41, p. 1470 (1949).
( 12) Van der Wel, G.K. and Adan, O.G.C., “Moisture in Organic
Coatings,” Prog. Org. Coat., 37, p. 1-14 (1999).
( 13) Baier, R.E., Shafrin, E. G., and Zisman, W.A., “Adhesion: Mechanisms
that Assist or Impede It,” Science, 162, p. 1360-1368 (1968).
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