Preparation of Copper Rosinate Emulsion and Its Resistance against Wood Decay Fungi

IRG/WP 13-30619

Mingxin Zhang, Shujun Li, Qian Wang, Bo Li, Qiong Wu

A leaching-resistant water-borne copper preservative was prepared by means of the following three steps: (1) Gum rosin was saponified with potassium hydroxide. (2) The soap reacted with copper sulfate to form copper rosinate. (3) The copper rosinate was emulsified with a mixture of Tween 20 and Span 80. Poplar (Populus ussuriensis) wood was impregnated with 0.5%, 1.0%, 1.5%, or 2.0% of the copper rosinate emulsion. A two-week leaching test proved that the copper was well fixed in the wood, and the leaching rates of copper were only around 15%. Wood decay resistance was measured by a soil-block culture method with Trametes versicolor and Gloeophyllum trabeum as test fungi. All the wood blocks treated with high concentrations had strong decay resistance. Scanning electron microscopy coupled with energy dispersive X-ray analysis (SEM-EDX) confirmed that copper was still in the cell lumens of leached wood blocks even after 12-week fungal exposure, and some copper rosinate was hydrolyzed due to high humidity during the decay test.

Keywords: copper rosinate, emulsion, wood preservative, leachability, decay resistance

Conference: 13-06-16/20 Stockholm, Sweden

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