Chemical recycling of laminate films composed of polyamide and polyethylene with water at high temperature and pressure

In order to establish a decomposition and recycling technique of a laminate film consisting of nylon-6 and polyethylene layers, we investigated the conditions to decompose nylon-6 layer to a monomer of epsilon-caprolactam and, at the same time, to recover polyethylene layer as pure polyethylene using water at high temperature and pressure at 300 similar to 350 degrees C and 8.6 similar to 16.5 MPa. At first, we confirmed that nylon-6 alone was hydrolyzed to epsilon-caprolactam without any catalyst at 330 degrees C, 12.9 MPa (vapor pressure of water), and 30 min of the reaction time. Next, the laminate him was hydrolyzed at the same temperature and pressure conditions, and we found that nylon-6 was decomposed into epsilon-caprolactam. This product was dissolved in water soon. On the other hand, polyethylene was stable under this condition and could be collected as a solid because polyethylene was insoluble in water. The yield of epsilon-caprolactam was 94% and the yield and purity of polyethylene were 95% and almost 100%, respectively.