Fabrication of solvent-based alkyd paint from disposable PET water bottles: A comparative study

Resumo

This comparative study aims to prepare alternative and cheap solvent-based paint using a waste PET-based alkyd resin synthesized from waste PET intermediate, suitable for coating applications. Waste PET flakes obtained from grinding post-consumer water bottles were depolymerized by the glycolysis reaction at atmospheric pressure. The depolymerization product was extracted by hot water, and a water-soluble crystallizable fraction (WSCF) and water-insoluble fraction (WIF) were obtained. WSCF was completely used instead of the diol component in the synthesis reaction of a four-component PET-based alkyd resin that has an oil content of 60%. Besides PET-based alkyd, reference alkyd without waste PET intermediate was also synthesized. Then, solvent-based paints were prepared using PET-based alkyd, reference alkyd, and commercial alkyd as binders. Wet paint properties and physical/chemical dry film properties of paints were determined. It was observed that the viscosity, density, hiding power, and particle size values of the paint prepared with waste PET-based alkyd were in the range suitable for paint applications, and the hiding power of waste PET-based alkyd paint was better than reference and commercial alkyd paints. Glossy, relatively soft, flexible paint films with excellent adhesion strength and impact resistance, and relatively high abrasion resistance were obtained from waste PET-based alkyd paints. It was observed that the resistance of waste PET-based alkyd paint to household chemicals was better than the paint prepared with commercial alkyd, and its resistance to ethyl alcohol, vinegar, and beverages was excellent. Waste PET-based alkyd paint was less affected by solvents than commercial alkyd paint. The environmental resistance of waste PET-based alkyd paint is excellent, and the oven-cured waste PET-based alkyd paint showed excellent resistance to corrosive conditions. The use of waste PET-based alkyd resin in the paint formulation did not cause any negative effects on the wet paint, physical/chemical surface coating properties, and chemical performance tests. As a result, PET-based alkyd paints, which are prepared using waste PET-based alkyd resins synthesized from the depolymerization intermediates of PET bottles, have the same or superior coating properties compared to commercial alkyd