This thesis presents a comparison of the properties of surface systems on melamine-faced particleboards finished with either a single-coat polyurethane coating system or a conventional two-coat system. Test specimens were sanded with abrasive papers of different grit sizes (180, 240, and 400). The measurements included gloss level, colour, wet- and cured-film thickness, adhesion strength, resistance to cold liquids, and impact resistance. It was confirmed that, in the conventional two-coat process, gloss values increase with the grit size of the sanding paper, whereas this trend was not observed for the single-coat application. Specimens with a higher coating weight exhibited a lighter surface colour, and – as expected – the two-coat specimens showed the greatest wet- and cured-film thickness. The highest adhesion strength (3.05 MPa) was recorded for specimens IV 240 and IV 240 V. Both were made from white melamine-faced particleboard sanded with 240-grit paper; specimen IV 240 V had a slightly higher coating weight. For the single-coat specimens with a higher application weight, the proportion of adhesive failure in the adhesion test was significantly higher (up to 100%), whereas all conventional two-coat specimens exhibited 0% adhesive failure. Resistance to water and coffee was excellent in all specimens (rating 5), while differences in impact resistance indicated a slight advantage for the single-coat specimens with a higher coating weight. The study shows that an optimised single-coat application can achieve surface quality comparable to that of a two-coat coating system.
|
