Heavy Duty Glass Flake Coatings for Arduous Anti-Corrosion Service

Abstract Glass flakes have been used for a number of years to reduce gas and moisture vapour diffusion through coating and paint films. Advances in glass flake production over more recent years, have allowed thinner and more consistent flakes to be produced. This has led to investigative work into the properties that can be attained by way of using glass flake as a performance improver. The work has investigated many materials both organic and inorganic and in many areas of use - such as tyres and even cosmetics. But, the biggest field of application is in organic resinous materials, not least of which, are those used in the area of corrosion protection for arduous service. Surprisingly, although the thin flakes (below 2 microns) are better performance improvers in most applications in some applications thick flakes (over 5 microns) are found to give better results. The high aspect ratio of a flake compared to fibres or granular fillers imparts unique properties to materials to which they are added but great care has to be taken in choosing addition level, thickness and size distribution to obtain the required result and for the optimisation of a particular characteristic. This work is tedious, time consuming and expensive but endeavour and patience can be amply rewarded. Areas of interest where the addition of glass flake can make significant improvements include; fire retardancy, mechanical reinforcement, UV light resistance, Tg and heat distortion, reduction in moisture vapour or gas percolation. Changes in the properties of thixotropy and viscosity, abrasion resistance, dimensional stability. Improved properties can be achieved not only in thermoset and thermoplastic materials such as unsaturated polyester, polypropylene and PTFE but also in materials such as paper and cement. However, these properties are combined to the greatest effect in paints and coatings used for corrosion protection and in particular heavy duty barrier coatings. Coatings produced using this technology have been shown to give outstanding performance and these have been used in industry, sometimes with good and sometimes exceptional result.