Acrylic‐ester‐polyol based novel two‐component polyurethane clear coat: Evaluation of performance characteristics

Abstract

In the current study, a combination of acrylic polyol (AP) and ester polyol (EP) were synthesized and reacted at variable ratios with hexamethylene diisocyanates and isophorone diisocyanates to prepare a transparent two‐component polyurethane (PU) coating formulation. The formations of the polyol system, isocyanate system, and the PU systems were confirmed by 1H nuclear magnetic resonance and Fourier‐transform infrared spectroscopy. Transparency of the coatings was examined using haze, and gloss measurement, which showed acrylic‐ester‐polyurethane (aePU‐5 and aePU‐6) have 91.5% and 91.8% transparency and gloss of 90.3 and 90.7 GU respectively. The thermal properties like Tg and the thermal stability of the coatings were verified using differential scanning calorimetry, and thermogravimetric analysis respectively which was found to increase with increasing EP content and decreasing AP content which may be ascribed to improved compatibility of copolymers, and homogeneity in PU along with enhanced crosslinking density. The degree of adhesion of coating with the substrate was validated from lap‐shear, and cross‐cut tape test which showed improved performance at AP:EP ratio of 60:40. The coatings were found to exhibit resistance toward pencil hardness with aePU‐5 and aePU‐6 having the optimum resistance of 9H. The surface morphology and topography were observed under scanning electron microscopy, and atomic force microscopy, respectively. The outcome confirms the higher smoothness of the surfaces subjected to the increase in EP content. The PU system with 40 wt% AP content and 60 wt% EP designated as aePU‐5 was found to exhibit optimum performance.

Fabrication of Polyurethane/Laponite/Graphene Transparent Coatings with High Surface Hardness

“…Coatings are generally used as thin films that protect or decorate the surface of objects, and their hardness reflects the ability of coatings to resist physical damage such as scratches, squeezing, and other effects caused by external objects [10,11]. However, polyurethane has a lower hardness after curing, which can easily cause scratches on its surface due to squeezing and scratching, which can seriously affect the aesthetics and the protective performance of the coating [12,13]. Therefore, it is necessary to find a method to improve the scratch resistance of polyurethane transparent coatings without affecting the aesthetics and visibility thereof.…”