Preparation and characterization of water-borne alkyd-amino baking coatings based on waste PET

The recycling of polyethylene terephthalate (PET) is the most attractive method for PET waste management because it not only decreases the load on landfill space, but also provides opportunities for reducing the use of raw petrochemical products. Therefore, in this investigation, waste PET was glycolyzed using neopentyl glycol in the presence of 0.5% zinc acetate as a trans-esterification catalyst at 220℃. The water-borne alkyd was successfully synthesized through polyesterification of the glycolyzed PET with tall oil fatty acid, phthalic anhydride, pentaerythritol, isophthalic acid, benzoic acid and trimellitic anhydride. Furthermore, the water-borne alkyd-amino baking coatings were prepared from the water-borne alkyd based on waste PET and melamine formaldehyde resin curing agents and applied on tinplate. The water-borne alkyd-amino baking coatings exhibited overall good performance properties except for alkali resistance due to hydrolysis of ester bonds.

聚对苯二甲酸乙二醇酯（polyethylene terephthalate, PET）的回收利用是PET废弃物处理中最具吸引力的途径，其不仅可降低填埋场的承载负荷，还能为减少石油化工原料的使用创造条件。据此，本研究以新戊二醇为醇解剂，以0.5%的乙酸锌作为酯交换催化剂，在220℃条件下对废弃PET进行醇解反应。将醇解后的PET与妥尔油脂肪酸、邻苯二甲酸酐、季戊四醇、间苯二甲酸、苯甲酸及偏苯三酸酐进行聚酯化反应，成功合成了水性醇酸树脂。进一步以该废弃PET基水性醇酸树脂与三聚氰胺甲醛树脂固化剂复配，制备得到水性醇酸-氨基烘烤涂料，并将其施涂于马口铁基材表面。该水性醇酸-氨基烘烤涂料整体性能优异，但因酯键水解问题，耐碱性能存在缺陷。