Functional properties of coatings based on novel waterborne polyurethane dispersions with green cosolvents

Three green sustainable cosolvents were used to produce polyurethane waterborne coatings. The effect of dihydrolevoglucosenone, gamma valerolactone and propylene carbonate on the performance of different coatings from a range of polyurethane structures with different hard segment content and different chain extender (a diol and a diamine) was studied. Properties of both synthesised polymers and water dispersions, like particle size distribution, stability, and pH, were carefully examined. The key properties of obtained coatings, including Koning hardness, specular gloss, hydrophobicity, abrasion resistance, adhesion or chemical resistance were detailly investigated to validate the use of these alternative green solvents in industrial coatings. The results indicated that the performance of materials based on sustainable cosolvents were equivalent to that of PUD coatings from commonly used cosolvent, N-methyl-2-pyrrolidone (NMP) maintaining a high gloss finished, as the properties of the dispersions keep optimal. Monomodal water dispersions with particle's diameter below 180 nm and stable for at least one month were achieved.