Evaluation of aesthetic durability of waterborne polyurethane coatings applied on wood for interior applications

Water-based coatings applied on wood are increasingly used for the respect of environmental legislation. The advantages of the reduced impact on the user and the environment are progressively associated to a high level of quality of coatings, comparable to solvent-based coatings. One of the requirements of coatings for furniture and interiors is the wide variety of aesthetic finishes and the ability to maintain a long-term appearance, colour and gloss stability in weathering and mechanical damage. In this work, the durability of waterborne polyurethane coatings with different aesthetic properties has been investigated. The samples were artificially weathered by ultraviolet radiation exposure. Colour and gloss measurements were carried out to evaluate aesthetic changes. Fourier Transform Infrared Spectroscopy was used to determine any chemical degradation of the polymer bonds. Taber test and falling abrasive test have been used to simulate the coating abrasion and erosion respectively. Gloss retention and weight loss were measured for the different coatings. Environmental scanning electron microscopy has been used to study the surface morphology after the damage. The obtained results highlighted the differences between transparent and pigmented coatings and the influence of initial surface roughness and gloss properties on coatings mar resistance.