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Replacement of CONVENTIONAL GLAZE on tiles and other high temperature processed materials with with novel hybrid coating

Final Report Summary - NOVACOAT (Replacement of CONVENTIONAL GLAZE on tiles and other high temperature processed materials with with novel hybrid coating)

In the NOVACOAT project, novel, inorganic-organic hybrid coatings were investigated in order to deliver a durable, low temperature coating that would eventually replace the glaze layer in twice-fired wall tile manufacturing. Hybrid coatings are particularly appealing because of the reduced temperature at which they are cured allowing the use of organic dyes and new decoration effects or functional effects currently not available with traditional inorganic based glaze coatings. Compared to the organic polymer coatings the hybrid coatings often provide a higher abrasion resistance and chemical resistance, which are important factors in wall tile applications.

The new effects that were explored in the NOVACOAT project included fluorescent, basic red and true trichromatic colours as well as holographic effects. Trichromatic printing in combination with decoration techniques such as traditional ink jet printing would allow any colour and design to be achieved by combining just three or four colours (cyan, magenta, yellow and black). This would represent a highly efficient method of decoration for ceramic producers. Also, the use of a low temperature coating process can significantly reduce the manufacturing cost. For instance, no second firing is required potentially reducing the carbon dioxide (CO2) impact of those products. The above mentioned features should stimulate a growth in niche products that Small and medium-sized enterprises (SMEs) are best placed to exploit. However, these novel coating materials have to retain important key features normally associated with wall tiles, such as strength, hygienic and aesthetic features.

In the NOVACOAT project, several hybrid coating compositions have been developed to suit the specific requirements of ceramic tiles production and use. Although improvements in specific properties have been obtained, the 'best' coating developed in this project failed to meet the expected specifications. In particular, the NOVACOAT coating failed to achieve the high chemical (alkali, acid) and abrasion resistance required, making the hybrid tiles unsuitable for use in bathrooms and kitchens. Accordingly, the consortium concluded that although promising aesthetic results were obtained the hybrid coating developed by NOVACOAT project requires further development before it can be used for commercial applications.

Interestingly, in the last six months of the project new hybrid coatings were introduced in the market, indicating an increasing interest of commercial glaze suppliers in trying to meet the desire of tile manufactures to develop innovative solutions for decoration.

For instance, a well-established glaze supplier has presented a coating called Hydro at the 2007 Cevisama exposition. The coating is aimed for third firing applications. The consortium was also made aware of a hybrid coating from an Italian company that was recently introduced to the tile market. However, no sample material of this coating could be obtained. The Hydro coating was evaluated as a benchmarking exercise for the NOVACOAT. The chemical resistance of the Hydro coating was higher than of the 'best' water-based NOVACOAT coating. Also, the coating could be used in combination with organic dyes providing possibility to create tricromatic decorations. However, the abrasion resistance and adhesion on the (glazed) tile surface of the Hydro coating did not meet the specified performance. These new products confirm the interest in the ceramic tile market for this type of products. However, in common with the NOVACOAT material developed in this project, even the commercially introduced products still have weaknesses that will limit the scope of a commercial use in tile applications. Accordingly, the dissemination of the NOVACOAT project focussed on describing the challenges faced by the consortium, in order to improve the durability of the current hybrid coatings and to stimulate the Research and development (R&D) efforts in the field.

Although the NOVACOAT coatings did not reach the commercially acceptable specifications, the project made significant advances in understanding and exploiting the new design possibilities of hybrid coatings. This should provide noteworthy competitive advantages for the participating tile manufacturers when hybrid coatings that will meet the specifications become commercially available. Another important achievement of the project is the development of a new entirely water based formulation for the NOVACOAT coating, with chemical and mechanical properties similar to the organic based coating previously commercialised by EPG.

Wider objectives included promoting novel technologies to meet industrial requirements. Beyond the business opportunity for the participating companies, the NOVACOAT project also contributed to transferring novel technologies to the tile manufacturers and vice versa. For instance, the German SME manufacturer of the hybrid coating for metallurgical applications (EPG) successfully used the VELA, a deposition technology currently in use for glazing ceramic tiles and produced by EUR, thus improving competitiveness of the sector and helping to maintain and expand current employment levels.

The NOVACOAT project demonstrated the aesthetic potential of hybrid coatings as well as the remaining limitations compared to the hardness and chemical resistance of inorganic glaze coatings. Although the tiles with the NOVACOAT coating are not commercially acceptable due to the low alkali resistance, the designs proposed and demonstrated in this project together with the factory pilot trials provided a solid basis for the companies to develop their operational and marketing strategies if / when hybrid coatings with sufficient mechanical properties start to appear in the market. Although neither the NOVACOAT nor the Hydro coatings have met all of the specified requirements, the activities suggest that significant developments in the low temperature coating field can be expected in the coming years.

The developing hybrid and nanocoatings have the potential to meet the challenging high specifications regarding the chemical and abrasion resistance in wall tile applications. With the growing interest in the marketplace, a commercially acceptable solution can be expected in the near future. The results and conclusions of the NOVACOAT project will be disseminated via conferences and technical papers (three technical papers to be submitted for publication) to the public in order to promote interest in further developing the hybrid coating technology to such a stage that it can be widely adopted by the manufacturing base. However, the tile manufacturers that took part in this project will have a significant advantage in knowing how to fully exploit the decoration possibilities of such coatings.

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