German researchers develop furniture varnish based on vegetable oils, sugars

17-Apr-09

Fraunhofer researchers at the Institute for Wood Research, Wilhelm-Klauditz-Institut WKI (Braunschweig, Germany) have developed alternative furniture varnishes based on vegetable oils and sugars which is said to provide identical properties to the currently available petrochem-based varnishes and is economical to procduce. The furniture varnish contains roughly 50% renewable raw materials and offers the same hard-wearing, scratch proof and chemical resistance qualities as conventional varnishes. The new varnish is based on the chemical compound 1,3-propandiol, which is derived from glycerin. Glycerin in turn is the basic substance found in all vegetable oils, and is readily available as a byproduct of manufacturing processes for fatty acids and biodiesel, for example. The varnish uses comparatively cheap 1,3-propandiol as raw material instead of more expensive petrochemical feedstocks with no change in coating properties of the varnish. In the laboratory synthesis, the researchers transform 1,3-propandiol into polyurethane, which serves as a binder in hard, transparent, scratch-resistant varnishes. A good varnish needs to be hard, but also capable of amortizing shocks to a certain extent, so as to prevent damage to the item of furniture beneath the coating. The new varnish also contains no N-methyl-2-pyrrolidon (NMP), a solvent once widely used in polyurethane coatings. This substance is meanwhile known to have a toxic effect on the growing embryo and is classed throughout the EU as a hazardous chemical requiring a warning symbol on all products containing a concentration higher than five percent.