Developments in high-performance fluoropolymer resins offer promise for new applications and expanded use in architectural, commercial, and protective coatings, a speaker at the American Coatings Conference (ACC) said during the conference program this week in Charlotte, N.C.
Winn Darden, AGC Chemicals Americas, addressing an ACC session on Protective Coatings presented by SSPC, reported on "Advances in Fluoropolymer Resins for Long-Life Coatings." Darden said these advances include water-borne dispersions of fluoroethylene vinyl ether (FEVE) resins, a type of fluoropolymer, and silanol-functional FEVE resins for demanding exterior applications that cure without the use of isocyanates.
The SSPC session on protective coatings also featured presentations on low-VOC colorants, the formulation of low-VOC protective coatings, new additives for environmentally friendly coatings, and the importance of independent product-performance verification.
The SSPC session was part of the AC Conference being presented in conjunction with the American Coatings Show. The events are sponsored by the American Coatings Association (formerly the National Paint & Coatings Association and Federation of Societies for Coatings Technology) and Vincentz Network, with show management by NurnbergMesse North America Inc
In his presentation, Darden first reviewed the development and use of high-performance coatings based on fluoropolymer resins-including the formulation of fluorourethane air-dry coatings for field application. Turning his attention to recent developments, he said water-borne dispersions of FEVE resins have been formulated into coatings that exhibit superior performance properties compared to previous water-borne coatings based on emulsions of FEVE resins. Coatings based on the emulsions tended to fare poorly in comparison to conventional solvent-based versions, exhibiting higher water sensitivity and inferior weatherability.
With the use of the dispersion chemistry, Darden said zero-VOC fluorourethane coatings can be formulated that offer comparable performance to conventional high-performance solvent-borne versions. Such dispersion-based coatings offer the potential for use in applications where solvent-based field-applied coatings are currently used, even in areas such as Southern California where regulations dictate very low VOC content.
The dispersion-based coatings also could replace solvent-borne coatings in sensitive applications where solvent odor is problematic, such as office buildings or hospitals. Additional markets include industrial maintenance coatings, and coatings for automotive and aerospace applications, he said.
Premium architectural-coatings blends
Darden also reviewed development work involving blends of FEVE resins with conventional resins such as acrylics, which offers the potential for formulations that deliver greatly enhanced weatherability in architectural coatings used in traditional residential and commercial markets. These one-component coatings have demonstrated strong weathering performance in formulations where the FEVE resin makes up approximately 20% of the coating's resin content, in blends with acrylic resins, he said.
Additional development work is focused on optimizing the most cost-effective FEVE addition levels, since architectural coatings based on these high-performance resins would carry a significantly higher price tag than conventional architectural paints and coatings, he said.
Darden said potential markets for these premium architectural coatings include "trade-sales" products for architectural and commercial uses, direct-to-metal coatings for light industrial applications, and decorative coatings for concrete. He said the decorative-concrete market presents particularly intriguing possibilities, due to the rapid growth of this market in recent years and the need for protection and enhancement of decorative concrete. This need is most acute in harsh environments, such as high-heat, high-UV settings, he said.
Non-isocyanate high-performance coatings
The most recent development in coatings based on FEVE resins, Darden said, is the formulation of high-performance silanol-functional products that can be manufactured without the use of an isocyanate to achieve cure in air-dry applications. This type of silane/fluoropolymer chemistry presents interesting possibilities for the use of high-performance fluoropolymer-based coatings in parts of Europe where isocyanates are prohibited due to concerns about their toxicity profile, Darden said. In addition, the technology offers potential in the U.S., in cases where non-isocyanate materials such as polysiloxanes are candidates for use in demanding architectural and protective applications.
In addition to long-term weatherability, these silanol-functional FEVE coatings exhibit a high degree of heat stability and chemical resistance, Darden said. With the right choice of additives, they offer potential use as antigraffiti coatings, and in traditional markets for high-performance fluoropolymer coatings: architectural, industrial maintenance, aerospace, and automotive.
The SSPC session on protective coatings also included the following presentations:
- Innovative Easy-Dispersing and Low-VOC Colorants, Romesh Kumar, Clariant Corp.;
- Formulating Very Low-VOC Fluoropolymer Latex Systems, Kurt Wood, Arkema Inc.;
- The VOC Odyssey: An Epic Tale of the Green World of Formulating Protective Coatings, Mike O'Donoghue, International Paint; and
- New Additives for Environmentally Friendly Coatings, John Du, BYK Chemie.