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Natural Sciences
and Technology

Functionalization of Surfaces

HAWK

Surface Modification of Wood and Wood Composites with Atmospheric Pressure Plasmas

Plasma applications have already been state-of-the-art technologies in a number of different industrial sectors, like the metal and plastic industries, for many years. At the HAWK, these processes are constantly under further development and expanded for use in other industrial sectors. The plasma treatment of wood and wood composites under atmospheric pressure, for example, is being developed into a market-ready process.

In conventional processing, wood and wood composites are often pre-treated, i.e. coated with a primer or sanded down, before they are processed any further with gluing, painting or varnishing, etc., to improve the adhesive properties of the surface. Problems such as these have already been solved in plastic and printing technology with the help of plasma technology for years. Plastic foil, for example, which is used to make regular plastic bags, is plasma-treated, making it possible to print on the foil in the first place.

Research has made it possible to transfer this process to wood and wood composites. The technical problems encountered here are a result of the different dielectric properties and the considerably thicker material of these substances.
In contrast to the few hundred micrometers of plastic used in plastic foil, it is necessary here to treat material thicknesses from up to 3-4 cm effectively under atmospheric pressure. The starting point for that is the dielectric barrier discharge under atmospheric pressure, whereby the work piece is taken through a plasma zone, which is formed between electrically isolated high-voltage electrodes at approximately 30 kV.

Compared with conventional treatment methods, this plasma treatment considerably increases the surface energies of wood and wood composites, which leads to improved adhesive properties for gluing and coating processes on these surfaces. In addition, this processing makes it possible to significantly increase the retention and penetration of preservatives and other modification reagents in wood veneers.
The most important research findings on this topic have been published in a number of different scientific journals (publication list).
This technology is an economical, environmentally friendly process that can be easily integrated into existing production processes and can be used for large as well as small-scale production.

For more detailed information and links to publications, please click here.