Bio-Based Polyurethane Coatings: A Review

Polyurethanes are one of the most important multifunctional polymers that are widely used in the manufacture of hard and soft foams, adhesives, coatings, films and other products. Polyurethanes are usually synthesized by the reaction between isocyanates and polyols. However, concerns over declining oil resources, environmental pollution, and the price of oil-based materials have led to significant efforts to develop polyurethanes and polyols from biorenewable sources, especially in the adhesive and coating industries. In the present study, a wide ranges of vegetable oils used in the preparation of polyurethanes are reviewed and the chemical structures and synthesis methods of polyol, polyisocyanates and bio-based polyurethanes from vegetable oils are investigated. Then the properties of adhesives and coatings based on biomaterials are disscussed and compared with the properties of commercial adhesives. Studies show that the type of vegetable oil, NCO / OH ratio, flexibility and the presence of other additives are the most important parameters that affects the performance of polyurethane adhesives and coatings.