Chemical recycling of PET: 2. Preparation of alkyd resins for air-curable high-solid paints

Recently, it was shown that recycled PET, mainly recovered from beverage bottles or films, can be used to produce monomers like terephthalic acid (TA) and ethylene glycol (EG) by hydrolysis, dimethyl terephthalate (DMT) and ethylene glycol (EG) by methanolysis or bis(hydroxyethyl) terephthalate, BHET, by glycolysis with ethylene glycol. It was also shown that PET can be used to prepare products of more complex composition, containing terephthalate and ethylene glycol units alone or along with units deriving from other monomers. Among the resins prepared from PET, only AST3 has a good behaviour at short times of contact (or for thinner films). The behaviour towards the resistance to gasoline is good for both the control resin and for AST3. Finally, the mechanical properties of paints derived from the AST3 resin were compared with those of paints prepared from the control. The results showed that most of the properties are similar, only the hardness is lower for the resin produced from recycled PET.