| Abstract [eng] |
Nowadays from the industrial point of view, aesthetic view and service life of the wood products, which are exploited in outdoor conditions, is an important indicator [1,2]. Clear wood coatings, which are mostly used to express the natural texture and colour of the wood, have a low resistance against harmful atmospheric factors. However, small amount of inorganic nanoparticles, e.g. most commonly used zinc oxide (ZnO), cerium dioxide (CeO2) and titanium dioxide (TiO2) incorporated in transparent water-based coating stucture have a promising photostability of the coating system against harmful atmospheric factors and especialy – against ultraviolet light rays. Moreover, there is a theory, that increasing the amount of nanoparticles in coating structure, the latter’s can penetrate and distribute preferably in wood surface layers which can lead to the different interlock strength, but it's not yet well investigated. Thats why the main task of this work is to evaluate ZnO and CeO2 nanoparticles, as additives of inorganic metal oxide, impact on the adhesion stregth of clear water-based acrylic wood coating (AK) to surface of softwood. For the research the samples of pine (Pinus sylvestris L.) wood were used with dimensions of 45×45×20 mm. Pine wood samples were defect free, kiln dried, radialcutand sanded (120-grit, by FEPA). In order to reduce the influence of wood anatomy and surface processing, the average wood density, surface grain direction, moisture content, number of the annual rings per 1 cm were evaluated. Early and latewood surface roughness parameters Ra, Rz and Rmax were measured using contact stylus profilometer „Mahr Marsurf PS1“. Later, pine wood samples were coated with transparent water-based acrylic (AK) wood coatingcontaining six different concentrations of the ZnO and CeO2 nanoparticles (up to 5 %). The adhesion strength was assessed using the pull-off method. After the each test, the nature of the fracture was evaluated visually. It was determined that increasing concentration of ZnO and CeO2 nanoparticles in AK coating structure, the adhesion strength to pine wood surface change significantly. CeO2 nanoparticles, incorporated into acrylic coating, increased the adhesion properties of the coating. The highest adhesion stength was observed when the amount of CeO2 nanoparticles in coating structure was 5%. However, the results of ZnO nanoparticles in acrylic coating structure did not demonstrate such a good adhesion strength as with CeO2 nanoparticles additives. |
