As part of an international research project, scientists have investigated to what extent atmospheric plasma can be useful in the surface modification of wood-based materials. The results of this research are relevant for a large number of applications.
Agar plates with E. coli: in contrast to the uncoated wood (left), the wood with an APCVD coating with silver (right) has an antimicrobial effect.
Innovent e.V.
As part of an international research project, scientists from Innovent e.V. Technologieentwicklung Jena research institute (Germany), the Institut für Holztechnologie Dresden (IHD) and the Tomsk State University of Architecture and Building (Russia), together with partners from industry, have investigated the possible effects of atmospheric plasma on the surface properties of wood and wood-based materials for certain applications.
In the course of this research project, atmospheric plasma sources were used to produce thin, functional silicon oxide-based films on wood and wood-based materials. These films are only a few nanometres thin and therefore almost invisible to the human eye. Silicon oxide films can be used to influence the wetting properties of wood surfaces, from highly hydrophilic to highly hydrophobic. The scientists also succeeded in embedding special active ingredients in the films to specifically generate new surface properties that cannot be provided by a pure silicon oxide coating alone.
Improved adhesion for lacquering
It has been known for some time that plasma activation of plastics and hence also of plastic-based WPC materials can improve adhesion for subsequent bonding, printing or lacquering. Furthermore, scientists showed in experiments that the adhesion of subsequently applied varnishes or glazes also increases following plasma coating on wood. This had a particularly positive effect on lacquer adhesion when exposed to moisture. The artificial and natural weathering tests both showed that the thin plasma coating did not negatively affect the degree of gloss or colour change. Yet after weathering, the lacquer adhesion was still significantly higher than with conventionally coated comparison samples. The researchers see its potential mainly in the exterior application of wooden materials, in veneer processing and in window construction.
Antimicrobial coatings
The scientists were able to show that the specific embedding of active agents in plasma layers can lead to significant germicidal and partially fungicidal surface properties. The scientists see its use mainly in wooden products such as handrails or other special furniture products that are used in public areas with heavy pedestrian traffic. The weather-resistant coatings are also of interest for outdoor use, for example for panel products made of wood or WPC, as well as window construction, or even wooden spectacle frames or wristwatches.