BRIEF COMMUNICATION Epoxy-based paints from glycolysis products of postconsumer PET bottles: synthesis, wet paint properties and film properties Kevser Bal, Kerim Can U ¨ nlu¨, Is¸ ıl Acar, Gamze Gu¨c¸lu¨ Ó American Coatings Association 2017 Abstract Glycolysis of waste polyethylene terephtha- late (PET) flakes obtained from grinding postconsumer bottles was carried out at 180–190°C, and molar ratios of PET/EG were taken as 1/6. Reaction product was extracted by hot water, and water soluble crystallizable fraction and water insoluble fraction were obtained. These fractions were characterized by hydroxyl value determination. Water soluble crystallizable fraction obtained from glycolysis product was used for synthesis of PET-based epoxy resin. Two epoxy-based paints were prepared using different amounts of PET-based epoxy resin. Wet paint properties, and chemical and physical film properties of paints containing waste PET were determined. Increasing the rate of PET-based epoxy resin in paint formulation did not have a negative effect on the wet paint properties and dry film properties of epoxy-based paints containing waste PET. Keywords Epoxy resin, Polyethylene terephthalate, Depolymerization, Glycolysis, Paint Introduction Polyethylene terephthalate (PET) is a thermoplastic polyester produced by the reaction of terephthalic acid and ethylene glycol (EG) or dimethyl terephthalate (DMT) and EG, which is produced for many applica- tions, such as high-strength fibers, video and audio tapes, photographic and X-ray films, and various types of packaging materials such as soft drink bottles, due to its clarity, light weight, and selective gas permeabil- ity. 1–8 PET is one of the most extensively recycled polymeric materials, and PET recycling represents one of the most common examples of polymer recycling applications. 1,9 Since PET wastes have high resistance to the atmospheric and biological conditions, they cause significant visual pollution to the environ- ment. 5–7,10,11 In addition, the use of waste PET-based materials contributes to the conservation of energy and petrochemical raw materials. 3,8 PET collection and recycling has continued to increase over the last 25 years. In 2007, postconsumer PET collection rates reached 1.13 million tons and 1.7 million tons of PET were recycled in Europe in 2014. In the same year, 57% of PET bottles and containers placed in the market were collected for recycle. 12–14 There are two main approaches for the recycling of waste PET, namely mechanical and chemical recycling. Mechanical recycling is one of the main methods for recycling PET, but chemical recycling methods such as glycolysis, hydrolysis, aminolysis, aminoglycolysis, hydrolysis–gly- colysis, alcoholysis have also gained importance in recent years. 15 Glycolysis is a depolymerization meth- od commonly used in chemical recycling of waste PET. Different glycols such as ethylene glycol, 4,16 propylene glycol, 17,18 diethylene glycol, 17 triethylene glycol, 18 dipropylene glycol, 17 and glycol mixtures 18 were used in glycolysis process of waste PET in the literature. Oligomeric diols and bis(2-hydroxyethyl) terephthalate were obtained by glycolysis dependent on process conditions in these studies. 4,14 Glycolysis products of waste PET were used for the production of different polymeric coating binders, such as alkyd resins, 9,14,19,20 alkyd–amino resins, 17 and polyurethane resins, 21 as raw materials. A literature survey showed that there are two articles about usage of glycolysis products for synthesis of epoxy resin 22 and epoxyester resin. 4 However, there is no report on using of glycolysis products of waste PET for synthesis of epoxy-based paint and investigation of wet paint K. Bal, K. C. U ¨ nlu¨, I. Acar, G. Gu¨c¸lu¨(&) Department of Chemical Engineering, Faculty of Engineering, Istanbul University, 34320 Avcılar, Istanbul, Turkey e-mail: gguclu@istanbul.edu.tr J. Coat. Technol. Res. DOI 10.1007/s11998-016-9895-0