Validating chemical PA 6 recycling for automotive applications

Toray Industries signed an agreement with Honda Motor Co to jointly develop a chemical recycling technology for glass-fiber reinforced polyamide 6 parts recovered from end-of-life vehicles. The two have begun verifying this technology, which entails depolymerizing with subcritical water and regenerating the materials as caprolactam, a raw monomer.

The two companies focused on such subcritical water characteristics as its high permeability, dissolving power, and hydrolysis effect in resins in developing a technology that successfully depolymerizes PA 6 with that water. Subcritical water is water at high temperatures and pressures. It is free of catalysts, additives do not affect it, and it can depolymerize PA 6 in several dozen minutes to create high yields of raw monomer. Separating, refining, and repolymerizing that monomer makes it possible to regenerate PA 6 that performs like a virgin material.

The Japanese Ministry of the Environment adopted this technology for a fiscal 2023 project to establish a decarbonized circular economy system, including to validate recycling systems for plastics and other resources. Toray and Honda look to employ that project to set up a pilot facility with a processing capacity of 500 metric tons annually of raw resin, conducting validation testing with it.

The first step with this work is to recycle used automotive plastic parts into the same automotive materials. The two companies will develop depolymerization and monomer separation and refining technologies by employing intake manifolds as raw materials for engine intake system parts. They seek to apply these technologies for recycling chemicals in automotive resin parts by around 2027.

Down the track, they look to broaden the scope of their chemical recycling technology to encompass apparel, films, and other non-automotive applications. They also envisage inviting other companies to take part in their effort and a set up a chemical recycling scheme for PA 6 in Japan. This endeavor would help realization a circular economy and cut greenhouse gas emissions.