New technology for the continuous production of wood-based lightweight panels

Lightweight boards in the wood-based panel and furniture industry are not a new topic. First trials to reduce the density of PB and MDF boards were mentioned more than one decade ago. - Sandwich panels with faces from thick veneer, plywood, thin PB or MDF and cores made from honeycomb paper, very light wood species or foams are also state of the art since at least two decades. The fast growing market of knockdown furniture on the one hand and the increasing costs for energy and raw materials on the other hand are additional factors that make weight saving a primary economical objective for most panel producers. Moreover, customers demand more for ergonomically solutions regarding packaging and transportation. A new one-stage production process for sandwich panels with wood-based facings made from veneers, wood particles or fibres and a core consisting of expandable particles is presented. It could be integrated in existing continuous pressing lines for PB and MDF manufacturing keeping the advantages of this produc-tion technique in matter of efficiency. The manufacturing of lightweight sandwich panels in a continuous one-stage process should combine the production of the dense facings and the very light core layer. During the first stage of the hot pressing process, the mat surfaces are compacted to high densities and the resin cures in this state. In a second stage, the press is opened to the final panel thickness. In this stage, the foam material expands and forms the lightweight core. The core material itself acts also as a bonding matter to the facings. The lightweight panels that were produced at lab scale reveal mechanical properties that are comparable to recently used wood-based panels while obtaining a weight reduction of 30-50%.