Novel, Water-Based Fluorinated Polymers with Excellent Anti-Graffiti Properties

摘要

In this paper we will describe novel aqueous, crosslinkable fluorinated polymers that form coatings with excellent anti-graffiti properties. The synthesis and the surface and bulk properties of these coatings are discussed. Using particle size measurements and free monomer analysis the emulsion polymerisation process is described in some detail. The incorporation of fluorine is studied by Gradient Polymer Elution Chromatography (GPEC). The surface properties of these coatings are characterised in terms of their surface tension as calculated from static contact angle measurements and the distribution of the fluorine atoms throughout the coating is measured by X-ray Photoelectron Spectroscopy (XPS). Atomic Force Microscopy (AFM) studies provide information about the development of the surface morphology in time and can, to some extent, be correlated with the anti-graffiti properties. The crosslink density is determined by Dynamic Mechanical Thermal Analysis (DMTA) and the effect of crosslinking on the bulk properties is considered. The crosslinking between the fluorinated polymers and isocyanate crosslinkers is monitored using infrared (IR) spectroscopy and the effect of the curing conditions on the anti-graffiti properties is discussed. The contribution of the concentration of fluorine and crosslinking groups on the anti-graffiti properties is highlighted and found to have a strong effect on the anti-graffiti properties. The reduced mobility because of the high crosslink density prevents the graffiti from penetrating the coating while the low surface tension makes easy removal of the graffiti possible. This combined action of surface and bulk properties gives these coatings their excellent anti-graffiti properties.