Investigation in the Pyrolysis of Polyester Coated on Aluminum-Based Beverage: Thermodynamic Properties, Product and Mechanism

Abstract

ABSTRATCPolyester coatings on the surface of aluminum cans were selected as raw materials. Thermogravimetric analysis, elemental analysis, Fourier transform infrared spectrometer and pyrolysis gas chromatography/mass spectrometry were used to study the pyrolysis behavior and pyrolysis products of the polymer components coated on the aluminum cans. TG analysis showed that pyrolysis of the coatings mainly occurred at 250~540 °C, with a weight loss of about 25% for blue and green, and a lower weight loss of 15% for yellow. The effect of pyrolysis temperature on the pyrolysis products of polyester coatings was investigated using PY-GC/MS. The results showed that the main products of pyrolysis included four major groups: oxygenated compounds, aromatic compounds, nitrogenous compounds and aliphatic hydrocarbons. Oxygenated compounds and aromatic compounds were the main products in the pyrolysis products of paints, such as neopentyl glycol, phthalic anhydride, toluene and styrene. At 600 °C, the aromatic compounds, oxide-containing reached 57~67% and 20~27%, respectively. The carbon numbers of the pyrolysis products of polyester coatings were concentrated in the C5~C8 range. In addition, the pyrolysis principles of the three main components of polyester coatings (polyester resins, amino resins, and acrylic resins) were postulated.

Keywords: Aluminum cans, pyrolysis, Polymer coating, Pyrolysis products