Project: “Wood Preservative”

Development of a biocide-containing wood preservative with extended efficacy and without the release of hazardous substances.

To ensure the effectiveness of chemical wood preservatives against wood-destroying insects and fungi, these products often incorporate toxic agents or biocides. However, exposure to environmental factors like rain and humidity frequently causes these substances to leach into the environment, creating risks to human health and ecosystems. This project focused on developing a wood preservative in which the biocidal agents are securely immobilized on the wood’s surface and within its structure. By preventing the release of biocides, the solution not only improves environmental and health safety but also extends the preservative’s durability and effectiveness over time.

This objective was achieved through the combined action of the following effects:

• Anchoring and immobilization of the biocidal agent (boric acid) within the wood’s surface and internal structure, significantly enhancing leach resistance.
• Durable hydrophobization of the wood surface, minimizing moisture exposure and prolonging the effectiveness of the biocidal agent.
• Impregnation with strength-enhancing compounds (e.g., silicification) or chemical cross-linking of wood fibers, offering mechanical protection and increasing the structural integrity of the wood

To immobilize boric acid, its strong tendency to form hydroxyl complexes was utilized. By binding boric acid to hydrophobic polymers, the wood could be both biocidally treated and hydrophobized in a single technological step.

The surface polarity of the treated wood was effectively reduced with a final coating, minimizing water penetration into the wood. This coating also included UV-protective agents and compounds that enhanced the wood’s structural integrity.

The reinforcement of the wood structure served two purposes: Preventive mechanical protection against wood-destroying organisms by making the surface more resistant to infestation as well as Stabilization of affected areas in infested wood, providing additional structural support.

The biocidal efficacy of the boric acid formulations was tested on treated pine wood according to EN 113: “Test method for determining the preventive effectiveness against wood-destroying Basidiomycetes,” using Coniophora puteana as the test fungus. Additionally, an accelerated 28-day test involved inoculating the treated samples with a spore suspension of Aspergillus versicolor, Penicillium chrysogenum, Trichoderma virens, and Chaetomium globosum, followed by incubation at 37°C and 95% relative humidity. Fungal growth on the wood surfaces was then evaluated to assess biocidal effectiveness.

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ANSPRECHPARTNER:
Dr. Helfried Haufe
Fachsektion Dresden – “Funktionelle Schichten”
Tel.: 0351 / 2695 344
E-Mail: dresden@gmbu.de