DURAWOOD

"Development of a cost-effective, durable coating system with low fungicide content for wood surfaces using Plasma Discharge"

 Partecipanti

Mappa

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 Obiettivo del progetto (Objective)

'For wood to compete with other materials and be attractive to customers, a durability of treated wood facades of at least 5-8 years renovation-free should be guaranteed. New EC legislation (2004/42/EC) requires the replacement of solvent-borne coating systems with water-borne coatings for outdoor wood preservation purposes. Wooden facades treated with water-borne coatings are more susceptible to discolouring and damage by mould and blue stain fungi. Mould fungi grow mainly on the surface of the paint film and harm the appearance of wood surfaces via their pigmented spores. Blue-stain fungi are capable of colonising the surface as well as the wood and wood-coating interface. They can penetrate the coating film enzymatically and mechanically, thereby damaging its protective functioning against the elements, leading to costly repair work after only a few years of service life. In order to sustain the use of wood in the face of growing competition from other materials, a need exists for cost-effective wood protection methods free from toxic preservatives, but which are capable of offering comparing durability. This project will develop a cost-effective, ecological, high performance wood coating system, offering low fungicide content. It is long known that the interaction of wood with water can lead to dimensional instability and accelerated bio, and weathering degradation. A variety of techniques have been investigated to achieve water repellent characteristics of wood surfaces, from liquid reagents, to thermal and chemical applications. A very promising technique to hydrophobize wood surfaces is the use of electrical gas discharges (plasma). This project will build on past research in this area to arrive at a DURAWOOD system that meets market needs in terms of price, durability and environmental protection. The RTD results will contribute to the continued growth of the EU wood industry, especially in light of global competition and new material alternatives.'

Introduzione (Teaser)

EU-funded scientists developed a novel pre-treatment technology to enhance the performance of coatings for outdoor wood products. Requiring much less energy and using water-based rather than solvent-based coatings makes it eco-friendly as well.

Descrizione progetto (Article)

Wood products for outdoor use are treated with coatings to protect against moisture and sunlight. European Commission legislation now calls for the replacement of solvents in coatings with water to eliminate the release of hazardous emissions from volatile organic compounds (VOCs) into the atmosphere. However, wood treated with water-borne coatings is more susceptible to fungi and weathering and it also tends to discolour easily. EU-funded scientists working on the DURAWOOD project enhanced the adhesion to wood of water-borne coatings, waterproofing performance and biocidal activity through the innovative application of plasma discharge technology.

Plasma treatment is already widely used in industry to activate the surfaces of plastics, textiles, glass and metals as a pre-treatment for coatings and other processes. However, standard atmospheric pressure discharge systems that are favourable to low-pressure ones requiring a vacuum are not easily applied to thick pieces of wood. They rely on placing the material between two electrodes and modifying the surface through high-frequency electrical discharges. Due to the very high resistance of wood, the extreme voltages needed consume a significant amount of energy and raise safety concerns.

DURAWOOD researchers employed planar electrodes in which the electrical current and ionised gas are confined to a thin layer above the electrode for high-volume power density to generate a high concentration of reactive species. By adjusting the conditions of the diffuse coplanar surface barrier discharge (DCSBD) treatment, the DURAWOOD system can either increase the wettability (hydrophilicity) of wood to enhance water borne coating adhesion or increase the initial water repellence (hydrophobicity) to block moisture absorption. The treatment even has significant inherent biocide activity on fungi already present in the wood, considered a potential initial decontamination effect.

Project outcomes enable cost-effective and improved application of environmentally friendly water-borne coatings to outdoor wood products for enhanced durability. Market uptake of the DURAWOOD technology will be encouraged by European Commission legislation to minimise the use of VOCs emitted by solvent based coatings and carbon dioxide emissions associated with the conventional pre-treatment processes. Both producers and consumers will have important benefits.