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30. Oct 2018 | Raw materials

Nature meets wood coatings

Every two years, the wood coatings community comes together to discuss the latest technical developments as well as regulatory affairs. But most importantly, the PRA Woodcoatings Congress 2018 showed again that it is a family meeting.

Miriam Peralta from Lubrizol receives the Holbrow Medal for the best paper at the woodcoatings congress from Peter Collins. (Picture: Jan Gesthuizen)

Most trends influencing the wood coatings market are similar to the ones in other coatings areas such as automotive paints or corrosion protection. However, PRA’s 11th Woodcoatings Congress showed that nonetheless many nuances are different. One example is the topic of bio-based coatings that was quite visible during the congress.

During a poll, the attendees of this year’s conference were asked about the share of bio-based materials they expect to be using in their formulations in ten years. 45 % of all voters expected to use 10 – 30 %. While this is clearly more than today and would lead to a growing market for this type of raw materials, this is of course not the most ambitious expectation. However, 23 % of voters assumed a usage of 30 - 50 % bio-based material and 9 % even more than 50 %. This means that there is a number of players who aim for ambitious targets.

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Poll results from the woodcoatings congress

Several lectures addressed bio-based materials and illustrated that – in some cases – the technology is further along than one would expect. Presentations on bio-based fire retardants, silyated linseed oils, nano- and microfibrilated cellulose or binders based on itaconic acid showed there are many suitable materials out there, just waiting to be used.

Water-borne wood coatings have room for growth

However, in terms of sustainability there is still a lot to do in other areas, too. For example, the share of water-borne formulations is still relatively low as Thomas Bernhofer from Synthomer exemplified during his presentation. He explained that currently only about 35 % of DIY trim paints are water-based. The industrial sector is even worse, here you will find only around 15 % water-borne wood coatings.

Bernhofer said that he expects the share will most likely to rise in the future since regulations like National Emission Ceilings (NEC 2020/30) will probably reduce VOC boundaries to 50 mg/l or even 30 mg/l, which is much lower than today’s 130 mg/L.  As he explained, this could lead to a more extensive usage of water-borne wood coatings, since the stricter benchmarks are already met by most water-borne systems. In countries with stricter regulations like Denmark or the Netherlands the water-borne-share is already at 90 % and more, Bernhofer underlined.

More durable wood coatings needed

However, as the polls showed, the major issues for the wood coatings industry are seen somewhere else. Asked for the biggest pull for innovations, more than 50 % of the attendees voted for higher durability. Accordingly, most attendees voted for chemical resistance being the most important property that needs to be improved in water-borne wood coatings.

This was at least partially reflected in the presentation by this year’s winner of the congress award. Miriam Peralta of Lubrizol received the Holbrow Medal, given out by the Oil & Colour Chemists’ Association (OCCA). In her talk she presented findings that could lead to increased aesthetic values of polyamide-based polyurethanes while maintaining the high durability and resistance that polyurethanes are known for. Lubrizol compensated chemical features of polyamide polyols that are responsible for their typically high melting points and high glass transition temperatures as well for being relatively hard polyols.

Glossy coatings are out of date

As Peralta explained, a major driver behind this development was the rising demand for matt coatings. Coatings formulated with this kind of polyurethanes showed good self-matting behaviour. Even though the matting had its limits at around 16 GU at 60°, the usage of matting agents could be reduced if an even higher matting is necessary. This could, as Miriam Peralta explained, reduce the negative impacts that using a high amount of silica or other matting agents could bring.

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Poll results from the woodcoatings congress

Maybe even more important than the lectures is the opportunity to speak personally to experts from the industry. The event in Amsterdam underlined that, within the coatings industry, the wood coatings community is possibly one of the most communicative ones. Some people described the event as a big family meeting. At times, it certainly felt like one.

Jan Gesthuizen

Disclaimer: The PRA Woodcoatings congress was organised in collaboration of PRA and Vincentz Network. The latter is publishing European Coatings and hosting its own conferences, trade fairs and seminars as well as events for major players in the coatings industry.

Book tip:

The comprehensive standard work Wood Coatings from Jorge Prieto and Jürgen Kiene focuses on interior and exterior coatings for wood and wood-based materials.

EC Library The Rheology Handbook

Books

The Rheology Handbook

Already in its 5th edition, this standard work describes the principles of rheology clearly, vividly and in practical terms. The book includes the rheology of additives in waterborne dispersions and surfactant systems. Not only it is a great reference book, it can also serve as a textbook for studying the theory behind the methods. The practical use of rheology is presented in the areas quality control, production and application, chemical and mechanical engineering, materials science and industrial research and development. After reading this book, the reader should be able to perform tests with rotational and oscillatory rheometers and interpret the results correctly.

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