For many automakers around the world, there is a strong desire or need to show an increasing amount of post-consumer-recycle (PCR) content in their vehicles, especially for polymeric materials. But finding PCR polymers that do not suffer from losses in physical, mechanical, and aesthetic properties has been difficult. Hence, for critical and safety-related applications, the maximum allowable recycled content necessarily has been kept low, and truly “green” (100%-recycled) applications have been quite limited in these materials. This has been especially true for the family of nylon thermoplastics, which are often used in applications with either safety and / or aesthetic requirements.
Since each passenger car built globally uses an average of 15 - 20 kg of nylon polymers, there is strong incentive to find a way to increase PCR content in components using these materials without losing properties. Fortunately, a new technology has been developed for nylon 6 resins to solve this problem. The process currently uses waste nylon 6 carpet as a feedstock - although provisions have been made to accept painted or unpainted, pigmented or unpigmented nylon 6 parts from other industries, including automotive. The process depolymerizes the nylon back to its caprolactam feedstock and in so doing chemically separates the nylon from other contaminants (e.g. latex backing). The caprolactam then is repolymerized into new “virgin” resin, which can be modified with fillers, additives, and colorants to create virgin-quality nylon 6 resins that are indistinguishable from those made from conventional caprolactam feedstock. A commercial-scale depolymerization plant that uses this process will be fully operational by October, 1999.
This paper will briefly discuss the new process, the products it produces, and the potential impact this could have on closed-loop recycling programs in the automotive industry.