Lastnosti površinskih premazov v odvisnosti od njegovih interakcij s termično modificiranim lesom

V Evropi so se razvili različni postopki termične modifikacije, za katere je značilno, da povečajo dimenzijsko stabilnost in biološko odpornost lesa. Odpornost termično modificiranega lesa proti fotodegradaciji pa ostaja bolj ali manj nespremenjena in površinska obdelava takega lesa je še vedno potrebna. V raziskavi smo proučili kompatibilnost devetih različnih premazov s termično modificiranim lesom rdečega bora (Pinus sylvestris L.). Z enoletnim staranjem v naravnih razmerah smo ugotovili, da se trajnost filmov premazov poveča, če so premazi naneseni na termično modificiran les. Ugotovili smo, da je razlog za to v spremenjenih lastnostih termično modificiranega lesa. Ta ima nižjo ravnovesno vlažnost, zmanjšano sposobnost absorpcije tekoče vode, povečano dimenzijsko stabilnost, boljšo UV-obstojnost in biološko odpornost, kot tudi boljše omakanje s premazi in globljo penetracijo premazov. Prav tako smo ugotovili, da so se sistemi s premazi na vodni osnovi po enoletnem staranju slabše izkazali kot sistemi s premazi na osnovi organskih topil, saj so bolj plesneli, filmi premazov pa bolj pokali. Dodajanje fotostabilizatorjev transparentnim premazom se je odrazilo v zmanjšanju luščenja in pokanja filmov premazov. Pigmentirani sistemi so bili v primerjavi s transparentnimi sistemi odpornejši. Rezultati večje trajnosti premaznih sistemov na termično modificiranem lesu so pokazali, da prilagoditev obstoječih premazov za les za uporabo na termično modificiranem lesu ni potrebna.Various heat treatment processes for wood modification have been developed in Europe, resulting in increase of dimensional stability and resistance to biological attack of wood. However, resistance of thermally modified wood against photodegradation remains almost the same and surface finishing of modified wood is still needed. The aim of research was to study compatibility of nine different coatings with thermally modified Scotch pine wood (Pinus sylvestris L.). One-year natural weathering test showed that the durability of coatings was increased when applied on thermally modified wood. This finding was explained by the changed characteristics of thermally modified wood, which, in comparison with unmodified wood, showed lower equilibrium moisture content, lower liquid water permeability, increased dimensional stability, better UV stability and resistance to blue stain fungi. Better wetting of thermally modified wood with coatings and deeper penetration of coatings into modified wood were observed as well. It was also established that after one year of weathering the systems with waterborne coatings showed inferior performance compared to the systems with solventborne finishes, exhibited by film cracking and moulding of the whole system. The addition of photostabilizers into the transparent coating formulation resulted in a decrease of flaking and cracking of the coating. Compared to the transparent systems, the pigmented systems proved as superior. The results of better performance of the systems thermally modified wood - coating compared to the systems unmodified wood - coating showed that adjustment of existing commercial coatings for use on thermally modified wood is not needed