Fluoropolymer Coatings for Architectural Applications
The fluorine atom has very unique properties, particularly very high electronegativity and low polarizability. As a result, carbon–fluorine bonds have higher energy and are stronger than C–H bonds. In addition, the incorporation of fluorine substituents into organic molecules can significantly affect their properties. In small molecules, enhanced acidity and lipophilicity can result, making these fluorine-substituted compounds ideal as pharmaceuticals. The oxidative stability, boiling point, polarity, and other electrochemical properties of organic molecules are also influenced by the incorporation of fluorine atoms. Fluorinated polymeric materials exhibit low surface energies, insulating properties, impermeability to gases, and high resistance to water, oils, chemicals, corrosion dirt pickups, UV radiation, chalking, etc.
These properties make fluoropolymers attractive as highly durable protective coatings in many different architectural coating formulations, particularly those intended for exterior applications due to the need for excellent weatherability. Fluoropolymers that are used as binders in coatings include polytetrafluoroethylene (PTFE, or Teflon®), fluorinated ethylene propylene (FEP), ethylene tetrafluoroethylene copolymer (ETFE), polyvinylfluroide (PVF), polyvinylidene fluoride (PVDF), and fluoroethylene vinyl ether (FEVE). PVDF and FEVE are the most widely used in architectural systems. Arkema (Kynar® and Solvay Solexis (Hylar®) are the two key manufacturers of PVDF, while AGC Chemicals produces FEVE (Lumiflon®). Typically, these materials are only sold to approved coating formulators (licensees).