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Visible-light curable latex and heavily pigmented coating systems

Exploitable results

Through the 1990s, the paint and coatings industry has made significant advances in the areas of safer and more sophisticated manufacturing practices as well as environmentally friendly products. One of the current trends is the switch from solvent borne to water-based technology, which however, needs to be improved in order to lead to products with optimum properties and extended applications. In the 3 years of VISLATEX, a realistic and cost efficient solution was suggested, by introducing an innovative approach that allows for slow curing under the influence of visible light or UV radiation. This was accomplished by combining the technology of polymer coatings and films with the proper aspects of photochemical technology, which led to the production of materials with improved properties and zero VOC content. The main target of the project was to provide a binder system with a post cure possibility, and the pertinent work was implemented through three main phases: - Development of proper binders, which were used in the production of photocrosslinkable waterborne coatings and 100% solids-heavily, pigmented coatings. - Development of photoinitiators, which absorb light in the visible (or near visible) region and are suitable for production of either colourless or white coatings after cure completion. - Development of latex and heavily pigmented coatings that can be cured when exposed to UV or visible light. A range of novel, well characterised polymeric materials, bearing special photochemically active sites have been produced and successfully incorporated into a variety of coating formulations. Suitable photoinitiators, of reasonable cost, which function in the presence of titanium dioxide, are not inhibited by oxygen and lead to colourless products, have been identified. The mechanism of the photoinitiation of the cross-linking reactions, which take place in the polymer films, has been studied in detail and the thermal and mechanical properties of the cured films have been evaluated. Recycling of the results and subsequent improvements have indicated the most efficiently curing polymer-photoinitiator combination. The performance of optimisation loops led to the design and ultimately the production of polymeric coating materials with improved properties compared to the ones existing in the market. As a matter of fact, some preliminary customer trials have proved the great potential for the application of pigmented coatings in the industry. Apart from the technological accomplishments, the significant scientific findings that were delivered during the project should also be highlighted. VISLATEX results are being disseminated throughout the European and worldwide scientific community, via lectures, talks, and publications, while the industrially valuable knowledge has been protected through appropriate patenting. The successful outcome of VISLATEX project as it is outlined above has just set the basis for the next steps towards further developments. The industrial partners are now in the process of commercialisation of new coatings suitable for household (waterborne latex coatings) and industrial (heavily pigmented metal coatings) applications. These novel products are based on formulations which by taking advantage of the special photochemical technology that has been developed during the project, indeed achieve both zero VOC levels and improved performance.