Preparation and performance of new leaching-resistant copper sulfide-based wood preservatives

The aim of this study was to develop a new type of micronized copper-based wood preservative that would improve the problem of easy leaching of copper ions associated with other copper-containing wood preservatives. Micronized copper sulfide (CuS) is simple to prepare, provides good anti-fungal protection, and is leaching resistant. The stability of micronized CuS, the extent of leaching of copper ions from wood, and the effect before and after deliberate leaching on antifungal efficacy were investigated. When the retention of CuS was 4.8 kg/m³, the wood mass loss rate after infection with Trametes versicolor, Gloeophyllum trabeum, or Neolentinus lepideus fungi was < 10%, and when the retention was 2.16 kg/m³, only 1.87% was leached. Then, micronized copper sulfide azole (CuSA) was developed to provide comprehensive protection against wood decay fungi, especially copper-resistant fungus Rhodonia placenta. Preservative effects and changes in the chemical and micromechanical properties of the treated wood were investigated. When the retention of CuSA was 1.92 kg/m³, the mass loss from leached wood blocks after exposure to Rhodonia placenta fungi was only 3.51%. There were a few significant effects on the chemical and micromechanical properties of treated wood. This study provides a new approach to the design and preparation of effective wood preservatives with less leaching.