Effect of primary driers on oxidative drying of high-solid alkyd binder: Investigation of thickness effects by mechanical tests and infrared spectroscopy

Abstract

Catalytic activity of four primary driers was investigated in high-solid alkyd binder modified with tall oil fatty acids. The drying activity was established by mechanical tests. Infrared spectroscopy was used for detailed investigation of chemical changes during the autoxidation process. Due to strong thickness effect, the infrared study was performed using attenuated total reflectance (ATR) technique, which measures spectra of a thin layer from the interface sample/ATR crystal (down surface of the sample). Coatings of 30-wet thickness were found to be enough thin to be considered as a homogenously dried bulk with negligible effect of oxygen diffusion. It makes the 30-layers very suitable for determination of kinetic parameters of the autoxidation process. For the first time, ATR-IR experiments on several samples of the same composition but different film thickness were used for detailed investigation of the thickness effect.