Plasma Modification to Improve the Adhesion Resistance of the Wood Coating

In this study, the effect of plasma modification on improving the adhesion resistance of solvent-borne and waterborne polyurethane coatings in wood was evaluated. For this purpose, wood samples of poplar with a moisture content of 8% and dimensions of 2×10×15 (L×R×T) mm were prepared and their surfaces treated with plasma for 60, 120, 300 and 600 seconds. Then, the surfaces were coated with a solvent and waterborne polyurethane coatings and they were measured by a Pull-off adhesive strength. The results of the contact angle test indicate that the plasma treatment reduced the contact angle and increase the wettability of wood surface. Also, the results of adhesion test after plasma treatment showed that the lowest and highest parameter were related to the solvent-borne (2.9 Mpa) and waterborne (3.4 Mpa) coating respectively, one of the effective factors is increase the surface hydrophilicity of wood by plasma treatment. Plasma treatment had a significant effect on increasing adhesion, so that the adhesion is improved with increasing treatment time, and the highest change in the plasma's effect per unit time was the 60-second. Thus, it can be claimed that the ability of plasma treatment to improve the adhesion of coatings depends on the type of coating resin and plasma treatment time.