Development of a novel antisapstain product

As a biodegradable product, wood is vulnerable to attack by microorganisms that can degrade it and cause loss in value. To prevent their colonization, wood can be protected by the application of chemical preservatives. Environmental and economic pressure on currently used chemicals has led to a situation where considerable effort is now directed toward the development of new preservatives. Among the most promising products are products that contain alkylammonium compounds (AACs). Based on laboratory tests, didecyl dimethyl ammonium chloride (DDAC) has been described as one of the most effective AAC used as wood preservatives. However, there were situations in the practice, where AACs had problems. Despite investigations into the reasons for these problems, no clarification was accomplished. This thesis describes the process of the development of a new wood preservative that would, while improving the characteristics of AACs, meet the objectives of efficient control of fungal growth, low toxicity, less potential for environmental impact, and easier disposal of treated products withdrawn from service. The project was divided into five general phases. The experiments of the first phase were designed to test several potential fungicides against moulds and stains in order to eliminate less promising formulations. In Phase 2, the research was extended to other groups of fungi, such as soft rot, brown rot, white rot and DDAC tolerant species. In both phases tests were done on agar plates. In Phase 3, the most promising formulations from Phase 1 and Phase 2 were tested on a wood substrate to determine the minimum amount of preservative that would be effective against sapstain fungi and moulds. In Phase 4, active components and additives were combined together in larger volumes and product formulation stability was investigated. The potential product solution was then submitted for toxicological testing. In the last (fifth) phase, the relation between efficacy and the required coverage and retention were examined by a simulation of real spraying conditions in wood treatment pilot plant. Samples of lumber were sprayed in the pilot plant with the test product and then stored outside in the yard to see if moulds, fungi or sapstain would develop. The results of this thesis relate to a synergistic wood preservative composition comprising a quaternary ammonium compound and an additional second active component. The laboratory work on agar plates and the wood substrate, as well as field tests after pilot-plant spraying, have shown that the new product works. It has proved its capability for controlling a large spectrum of wood destroying microorganisms and counteracting the phenomena of the development of fungal resistance toward the applied active components.Applied Science, Faculty ofChemical and Biological Engineering, Department ofGraduat