Esterified organosolv lignin as hydrophobic agent for use on wood products

Lignin from Spruce and Eucalyptus wood was isolated by organosolv process, and subsequently was chemically modified using a long aliphatic chain (12C) of dodecanoyl chloride as reagent, to obtain a hydrophobic lignin derivative to be used as protective agent on wood products. Each esterified lignin was applied on wood by two different methods In the first method, the lignin was applied as coating using for that a press moulding (current industrial processing technology) at two different conditions. The other method consisted in impregnation using acetone as solvent and immersing the samples during different periods of time. The chemical modification of lignins was confirmed by FTIR, GPC and DSC resulting in an increase of its molecular weight and great reduction of glass transition temperature, allowing to process lignin by press moulding besides improving the solubility in acetone. The wood hydrophobicity (WCA ≈ 140°), oleophobicity (OCA ≈ 120°) and stability against water and oil dramatically increase after treatments observed by dynamic contact angle analysis. Furthermore, the efficiency of treatments over time was confirmed by accelerated aging test. Aesthetical assessments, by meaning of color analysis (CIEL*a*b* system) showed significant differences between application methods, being more pronounced in case of coating treatments. Additionally, after aging test the color was quite stable.