The overall objective of this project is to develop a method for ultra-rapid weathering of paints based on plasma erosion, which should correlate with natural weathering results in terms of physical and chemical properties. This new method will be proposed for use in discriminating between good and bad paint performance at an early stage and in predicting the service life of coatings. An additional objective is to acquire information about the mechanisms of the degradation process by comparing plasma erosion and natural weathering.
Plasma erosion tests have been performed on several different paint systems and evaluated mainly by means of gloss and colour measurements. The combined UV and plasma exposure (first UV then plasma) has not given the improved correlation with natural weathering as expected. Although the desired correlation with natural weathering was found for some coating systems, it has not been possible to find a plasma condition that will give the desired correlation with natural weathering for all investigated paint systems. The use of plasma erosion method as a standard method for prediction of paint durability has therefore been considered as premature at present. More research and development is needed. Future research should focus on low power (no or low ion density) plasma and/or VUV exposure experiments for possible distinction between the relative performances of e.g. different grades of durable long-life polyester coatings.
Paint manufacturers recognise the importance of the durability of applied paint layers and are continually reformulating to obtain improved performance and minimised degradation. They are, however, faced with the problem of how to quantify this property of durability. The obvious method is to expose paint films to the weather and observe how rapidly they degrade. The main limitation to this method is the time it takes to obtain results. The more successful the paint industry is at producing long-life coatings, the more impracticable it becomes to test them by natural weathering. Rapid and reliable methods for predicting the durability of coatings are therefore needed. When using conventional weatherometers, it takes 6 months to a year to produce degradation equivalent to 10 years of natural weathering. Plasma erosion will produce the same degree of degradation in ten minutes that Q-UV or Xenon arc will produce in several thousand hours.
The work programme is divided into seven work packages, which include the preparation of paint samples; plasma erosion tests; comparative accelerated and natural weathering tests; and the physical and chemical characterisation of the exposed paint panels.y an
Funding SchemeCSC - Cost-sharing contracts
195 02 Märsta
593 25 Västervik
TW11 8LD Teddington