Several steps toward recovery
Going for the green
All OEMs are getting green, and not just in their fascias. As part of its policy to increase the post-consumer-recycle (PCR) content of materials used in its vehicles, Ford Motor Co. is using "the auto industry's first" green powertrain component molded from a repolymerized and recyclable nylon 6 resin. The application—a two-piece, engine-mounted, 5.4-L throttle-body adapter manufactured by Visteon Corp.—was designed and developed by Visteon Corp.'s Energy Transformation Systems Group to use a new repolymerized polymer developed by Honeywell, whose feedstock is produced by recycling carpeting and other nylon waste. According to Honeywell, this is the first time that material containing recycled content has been used on a high-performance part in the automotive industry, and the application represents the first commercial use of Infinity repolymerized nylon 6 resin, introduced by Honeywell a year ago, in the automotive industry.
Replacing a sand-cast and machined aluminum part, the throttle-body adapter will be available on Econoline vans, F-Series trucks, and Excursion SUVs with 5.4-L engine packages. Use of nylon for the adapter reduces mass by 510 g (18 oz) and tooling costs by 20% vs. aluminum due to the elimination of various machining and secondary-finishing operations. The use of Infinity nylon 6 in the adapter was cost-competitive compared to the use of virgin nylon 6 resin. Ford claims the new component meets all performance requirements of the aluminum adapter, including NVH, torque, and durability. Visteon anticipates manufacturing more than 130,000 of the 33%-glass filled, injection-molded part annually.
Producing a high-performance, engine-mounted part from recycled plastic has not been practical until recently. The recycling of polymers involves melt reprocessing of thermoplastics, a process that almost always leads to some sort of property degradation. With each heat cycle, further degradation can occur. Because of the potential for property loss, and the uncertainly over which properties will degrade and by how much on each molding cycle, it has been deemed too risky to include recycled content in parts used in high-performance or critical applications.
 RETAIN can be used in a variety of applications, including defroster grilles, speaker grilles, steering column shrouds, and interior trim (applications are shown in prototypes). |
Honeywell claims that what makes Infinity resin different from other thermoplastics with recycled content is that the material has been chemically renewed, not simply mechanically recycled (melt processed). Rather, high-quality nylon 6 resin has first been depolymerized—a process that "unzips" the molecular structure of the polymer into its constituent monomers (in this case, caprolactam)—and then the monomers are used to rebuild a new nylon 6 polymer from the ground up.
The result is another high-performance nylon 6 polymer with the performance, aesthetic, and processing attributes of virgin nylon 6, plus the environmental benefit of PCR content, according to Honeywell. This recycled nylon can be further compounded with additive, fillers, and colorant for customization and can be used in any application that currently uses virgin nylon 6 without property loss, if properly processed.
In the patented process by which Infinity is created, post-consumer carpeting is collected, sorted, and the nylon 6 carpeting is segregated from other types of carpeting by recyclers. A unique infrared scanner was developed for the separation purpose. Next, the nylon 6 carpeting is shipped to a recycling plant where it is fed into the recycling system, which also can accommodate molded nylon 6 parts with or without paint—and other nylon 6 waste. The carpet and parts are subjected to super-heated steam, which first separates the nylon 6 from other materials and contaminants (such as carpet backing), additional polymers, paints, fillers, etc., and then depolymerizes the polymer back into its caprolactam precursor. The caprolactam is then triple-filtered for purity and shipped to a nylon-processing plant where the recycled monomer is combined with virgin monomer and repolymerized back into a renewed nylon 6 polymer capable of surviving the high-temperature and chemically aggressive underhood environment. The waste materials separated from the nylon resin can also be recycled into other production processes.
With plants in Geleen, the Netherlands, and Augusta, GA, DSM Engineering Plastics is the world's second largest producer of caprolactam, accounting for about 15% of the material. The company's Akulon ReCap is a family of recycled nylons produced using the caprolactam depolymerization process. The first engine cover to use the material is slated for a production vehicle.
Recycled nylon has been widely used for a number of years but almost all of the products have been based on post-industrial fiber waste from spinning operations that are then remelted and blended to produce compounds. This process produces a cost-effective material that is suitable to numerous applications but does not normally meet the quality standards for virgin nylon. Materials based on post-industrial materials are typically only available in mineral and/or glass reinforced black compounds and not in colored or unreinforced materials.
Since Akulon ReCap products are based on virgin quality recycled caprolactam, they do not suffer the quality concerns that accompany post-industrial materials. They can be compounded in an array of colors and formulations.
Chemically recycling nylon waste into renewed resin offers a number of environmental benefits. At full capacity, the recycling plant is capable of diverting an estimated 115 million kg (250 million lb) of nylon carpeting, nylon waste, and worn parts annually that would otherwise be destined for landfill, reducing petroleum consumption and pollution that would otherwise be generated in producing virgin caprolactam. DSM claims that reduction in oil consumption would be enough to heat 100,000 average U.S. homes for a year. Repolymerizing nylon 6 resin also promotes closed-loop recycling and helps make nylon 6 production a sustainable and renewable process since nylon is being made from nylon, not from oil, which is just about as close to perpetual motion as we can get in 2001.
