New principles for the protection of wood: Impregnation with waterborne resins
A O Rapp, R-D Peek
The environmental impact of classical wood preservatives as well as the use of tropical wood species with high natural durability is regarded increasingly critically in the public. Therefore other partially new principles for the protection of wood, like chemical modification, or treatment with resins were examined especially in USA, Japan and in Europe with promising results predominantly in the lab scale. The work to be presented is focused on the feasibility to upgrade wood by a wide spectrum of water-borne resins under practical conditions of processing. The chemicals examined range from purely physically effective resins by hydrophobation and mechanical blockage up to such promising a chemical modification by their reactive groups. The behaviour of the resin solutions in a pressure process as well as the penetration parallel and orthogonal to the grain were investigated. Further, resin-uptake, improvement of hardness, and dimension stability, were examined. SEM studies are intended to show penetration pathways and linkage of the resins to the cell wall. Running tests on the investigation of the resistance against basidiomycetes and softrot fungi are not yet completed.