Lignin-Laccase-Mediator-Systems (LLMS) for the Production of Binderless Medium Density Fiberboards (MDF)

Medium density fiberboards (MDF) are produced mainly by urea-formaldehyde resins (UF) as binding agent, which are synthesized from finite fossil resources. Those boards may emit critical amounts of formaldehyde, which can influence the health of humans and animals. In recent times the wood panel board industry is looking for alternative glues which contain less or no formaldehyde. In order to avoid potential formaldehyde emissions altogether it would be preferable not to use binders which are formaldehyde based at all. One possibility is to use natural binders or to activate the wood fibers’ own binding forces by applying Laccase-Mediator-Systems (LMS). As a support of the LMS interactions with wood fibers technical lignin can be added. In this study it was found out that the addition of technical lignin intensified the fiber to fiber bindings. Two Lignin-Laccase-Mediator-Systems (LLMS) were analysed by Gel-Permeation-Chromatography and Cyclic voltammetry. Later the LLMSs were tested in the pilot scale production of MDF. The determination of the physical technological properties revealed that the LLMS treated MDF have higher dimension stabilities than only LMS treated MDF and approximately the same thickness swelling after 24 h. The results indicate that the application of LLMSs have a high potential for natural bonded MDF.