Synthesis, Characterization of Bio-based Polyol and Assess the Effectiveness of Bio-based Polyurethane Direct-to-metal Coating System

Abstract

Crude oil is neither a long-lasting energy source nor a raw material source, has a high consumption rate relative to a low regeneration rate and creates massive environmental disorders. Polyurethane is well known and is the most popular film forming material in the coating industry because of its better performance. A coconut oil-based polyol (biobased polyol) was synthesized and acid value, viscosity, reaction water release, oil length, FTIR spectrum, differential scanning calorimetry and colourimetric index were assessed during the synthesis. A series of pigmented wet paint samples were prepared by bio-based polyol and the optimum paint sample was selected among them based on drying time, pencil hardness, dry film thickness, cross hatch test and cylindrical mandrel blending. Two wet PU paint samples, representing commercially available crude oil-based polyols, were prepared to compare in the same aspects with a PU paint sample made with a bio-based polyol (BBP). According to the results, it was proven that bio-based PU paint showed equal magnitudes in film flexibility due to the cylindrical mandrel bending test, film hardness due to the pencil hardness test, substrate adhesion due to the crosshatch test and impact resistance. In some properties, bio-based PU exceeded at least one crude oil-based PU such as gloss, hard drying time and density. Meanwhile, bio-based PU systems must be improved in viscosity and water resistance to compete with artificial PU systems.