ABSTRACT
The present study is a part of an EUREKA-project - EU:455 Prowood - aiming to establish a general test and assessment methodology for environmentally friendly wood protection systems, and to apply the methodology for some actual formulations. These formulations comprise waterborne and toxicological acceptable pretreatments and paints, for which the protection efficiency and durability have to be verified. Wood panels with various pretreatments were top coated by two different, alkyd/acrylic based, trial paints. Three paints of conventional types - one alkydic, one acrylic and one alkyd/acrylic - were employed as reference top coatings. All types were exposed outdoors, while one of the trial paints, Tl, and the alkydic reference also were accelerated exposed in laboratory. The degradation of Tl was monitored periodically by means of Fourier Transform Infrared spectroscopy (FTIR) and X-ray Photo-electron Spectroscopy (XPS or ESCA). The FTIR measurements were performed by diffuse reflectance recordings of paint particles collected by abrasive paper; depth profiles were obtained from consecutive abrasions. Providing a careful specimen preparation, this extremely fast and cheep method is shown to give reasonable spectra. The analysis indicates e.g depletion of ester groups, crosslinking and formation of unsaturated groups, with only small variations as functions of depth. By XPS it is shown that the surface degradation differs from the “bulk” degradation. In addition the performance of all types of coated wood panels was evaluated by standardised inspection routines, where levels of gloss loss, fading, cracking, blistering, chalking, flaking, biological growth and soiling were estimated after one year outdoor and 3000 h accelerated exposure. Concluding from the results of spectroscopy and inspection, accelerated exposure yields similar degradation modes as outdoor exposure, except from effects of an exaggerated water load at accelerated exposure.
