Modified Wood

Modified Wood with EXPK195

Various methods of wood modification have been developed over the past decades. For example, the acetylation (“Accoya”) process, the Belmadur process, modification processes based on melamine resins, various heat treatment processes and furfurylation processes have been brought to production maturity and made marketable. In recent years, the focus has been on developing methods of modification with phenolic resins that can stand comparison with the methods mentioned above.

Metadynea Austria has developed a low-molecular and yet extremely storage-stable phenolic resin, the EXPK195. It is an aqueous, approx. 60% solution of a modified phenolic resin with a low content of free phenol and formaldehyde and a very low average molecular weight, suitable for modifying solid wood in thicknesses of up to several cm.

The Department of Wood Biology and Wood Products at the University of Göttingen, headed by Prof. Holger Militz, used small wood samples to investigate the ability to penetrate the wood lumen and the wood cell walls, the fixation and the dimensional stability. During a high temperature process the resin will cure and build a 3-dimensional network in function of temperature and time. All tests showed extremely positive properties and suggest that upscaling from the laboratory to processes relevant to practice will be promising. Wood species like radiata pine, European beech wood, poplar, and others treated with EXPK195 showed increase in hardness especially more pronounced beech wood, almost 2 times.

The combination of EXPK195 with halogen-free flame retardants, which are characterized by high compatibility with phenolic resin, is particularly interesting. It should be emphasized that the flame retardant is not washed out by cold water washing when used together. Thus, with this treatment, flame retardancy, dimensional stability, hardness, moisture resistance, etc. are improved in the long term and appropriate for outdoor use.

Due to the current market situation, processes for solid wood modification and veneering processes are to be expected. Possible products: windows, doors, facades, patio deckings, hydraulic engineering, gardening and landscaping, parquet flooring and various special applications.

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