Recent advances in perfluoropolyether (PFPE) resin technology for high solids, weather resistant polyurethanes for automotive (OEM) and heavy duty coatings are presented. In the former case, polyfunctional OH-terminated PFPE resins can be successfully blended with commercially available blocked iso- cyanates leading to high solids (70–80 wt.%) monocomponent polyurethanes with high density of cross-linking. Formulations containing PFPE resins and mixed hexamethylene diisocyanate/isophorone diisocyanate (HDI/IPDI) blocked isocyanates were prepared and char- acterized according to OEM specifications; the performances of fluorinated coatings were compared with those of reference acrylic solvent-borne coatings. Clearcoats were applied over conventional OEM basecoats (car body painting) and polyester powder coatings (wheels painting). The remarkable improvement of anticorrosion performances, acid and mar resistance and durability of painting system was reached maintaining its good aesthetic aspect. Fluorinated films showed excellent stain release properties conferring to final painting system, the self-cleaning behaviour typical for PFPE coatings. In the latter case, the use of dihydroxy terminated PFPE oligomers having properly selected molecular weights and bimodal molecular weight distribution allowed the preparation of really high solid (80–90 wt.% dry) low viscosity formulations with aliphatic and cycloaliphatic hydrogenated polyisocyanates. The compositions were able to cross-link rapidly even at temperatures below 20◦C giving fully transparent, chemically resistant and easy-cleanable coatings. The coating physical properties like hardness, glass transition temperature (Tg) and elongation can be optimized by tuning the hardener composition (HDI/IPDI ratio) as well as the molecular weight of the PFPE. White pigmented, high gloss finishes were also prepared and evaluated as protective barrier coating for heavy duty paints working in highly corrosive environments.

New developments in perfluoropolyether resins technology: high solid and durable polyurethanes for heavy duty and clear OEM coatings

DELUCCHI, MARINA
2001-01-01

Abstract

Recent advances in perfluoropolyether (PFPE) resin technology for high solids, weather resistant polyurethanes for automotive (OEM) and heavy duty coatings are presented. In the former case, polyfunctional OH-terminated PFPE resins can be successfully blended with commercially available blocked iso- cyanates leading to high solids (70–80 wt.%) monocomponent polyurethanes with high density of cross-linking. Formulations containing PFPE resins and mixed hexamethylene diisocyanate/isophorone diisocyanate (HDI/IPDI) blocked isocyanates were prepared and char- acterized according to OEM specifications; the performances of fluorinated coatings were compared with those of reference acrylic solvent-borne coatings. Clearcoats were applied over conventional OEM basecoats (car body painting) and polyester powder coatings (wheels painting). The remarkable improvement of anticorrosion performances, acid and mar resistance and durability of painting system was reached maintaining its good aesthetic aspect. Fluorinated films showed excellent stain release properties conferring to final painting system, the self-cleaning behaviour typical for PFPE coatings. In the latter case, the use of dihydroxy terminated PFPE oligomers having properly selected molecular weights and bimodal molecular weight distribution allowed the preparation of really high solid (80–90 wt.% dry) low viscosity formulations with aliphatic and cycloaliphatic hydrogenated polyisocyanates. The compositions were able to cross-link rapidly even at temperatures below 20◦C giving fully transparent, chemically resistant and easy-cleanable coatings. The coating physical properties like hardness, glass transition temperature (Tg) and elongation can be optimized by tuning the hardener composition (HDI/IPDI ratio) as well as the molecular weight of the PFPE. White pigmented, high gloss finishes were also prepared and evaluated as protective barrier coating for heavy duty paints working in highly corrosive environments.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11567/383121
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