Treatment of wood with aminofunctional silanes for protection against wood destroying fungi

Different aminofunctional silanes were tested for their suitability to preserve wood against basidiomycetes in a mini-block experiment according to EN 113. High effectiveness against the brown rot fungus Coniophora puteana was maintained over prolonged exposure times of up to 18 weeks. Resistance against the white rot fungus Trametes versicolor was only enhanced in the initial phase of exposure ( 6 weeks); after longer exposure times of 18 weeks, considerable mass losses were observed. It was shown that the antifungal resistance was caused by the amino groups of the oligomeric silane systems, while alkyl groups, which influence the water uptake of wood, only had a minor impact. For effective protection, acidic conditions of the treatment solution were important; this promotes the formation of cationised amino groups ( ammonium). The silane quaternary ammonium compound (Si-QAC) 3-(trimethoxysilyl) propyldimethyloctadecyl ammonium chloride was applied in combination with an oligomeric silane system to incorporate quaternary ammonium sites into a SiO2 matrix via a sol-gel process. This combined treatment significantly enhanced the decay resistance of pine wood against C. puteana.