Enhancing thermoplastic road-marking paints performance using sustainable rosin ester

The binder systems of conventional thermoplastic road-marking paint (TRM) formulations typically contain a thermoplastic resin and a liquid plasticizer/toughening agent. The liquid plasticizer often migrates to the paint surface and is leached away, negatively affecting the performance during its service life. The purpose of this study was to eliminate and/or reduce the liquid plasticizer from TRMs compositions by developing a sustainable thermoplastic resin compatible with the other resin types. To this end, a series of resins were prepared by reacting two bio-renewable based compounds including rosin ester compound, RE, with different amounts of epoxidized soybean oil, ESO via an esterification reaction. Various techniques were used to characterize ESO-treated RE. A variety of TRM paints were formulated by melt blending different types of resins, including; neat rosin ester, ESO-treated RE, hydrocarbon resin, and a mixture of both, and other essential components such as fillers and glass beads. The TRM coatings were then evaluated for softening point temperature (Tsp), color difference (ΔE), luminescence factor, β, before and after the heat stability test, and accelerated weathering performance. Taber abrasion, flow resistance, and cold impact resistance of the TRM samples were also determined. The drop-on glass beads retention of various samples was evaluated by means of a standard wash-ability test. The results revealed that the use of combination of sustainable ESO-treated RE and hydrocarbon-based resins improves the physical and mechanical properties of TRM materials thereby improving the compatibility between the components and increasing the toughness of TRM materials. The results also showed improved glass beads retention in the samples containing ESO-treated RE, probably as a result of interactions between the hydroxyl groups and some residual oxirane rings of the ESO compound with the hydroxyl groups on the glass beads’ surface.