Metal-based wood preservative systems

Whilst the heavy metal-based wood preservatives have insect protection capability, the organic and organ-metallic systems require the addition of a specific insecticide. 

The voluntary withdrawal of chromated copper arsenate (CCA) as a wood preservative for domestic applications was driven by public concerns over its health and environmental profile. In its place have risen two competing systems, the amine copper quat (ACQ) system and the copper azole system. Both systems avoid using heavy metals such as chromium and arsenic and rely on the co-biocidal effects of copper and organic biocides. The elimination of CCA has created many opportunities for oleochemicals as preservative companies try to develop formulations that are not only environmentally friendly but can also match the preservative performance of CCA [66]. The ACQ system is based on didecyldimethyl ammonium bicarbonate and has produced a significant demand for ClO-based amine and quat. The azole systems use biocides such as tebuconazole and propiconazole in combination with copper ethanolamine complexes. Ethoxylated amines [67] and amine oxides [68] have been described as providing improved performance in azole-based systems. Other copper systems have employed ethoxylated diamines [69] and amine oxides [70] to enhance performance. 

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