Renewable Nylon Applications Start to Surge

One of the hottest stories in engineering plastics now is actually one of the oldest - nylons made from renewable resources.
Nylon 11 derived from castor oil was first developed by chemists at IG Farben in Germany in the 1940s in a drive to make fuels and industrial products from sources other than petroleum. The rights were acquired by an American chemical producer after World War II and later sold to Elf Aquitaine in France, which successfully commercialized the material as Rilsan 11. It gained a market niche based on its unique property profile - and nothing to do with its environmental friendliness.
Rilsan 11 has been widely used for automotive applications such as fuel line tubing, particularly in Europe, because of its combination of chemical resistance and good mechanical properties. Elf Aquitaine is now part of Arkema, which has expanded the product line.
At K 2007, BASF, whose chemists working for Farben had developed the first castor nylon, announced introduction of Ultramid Balance nylon 6/10, which is about 60 percent based on sebacic acid, a material derived from castor oil.
"We have woken it up from a long sleep because the subject of renewable raw materials has become important to our customers," says Kurt Hoefli, head of marketing for BASF's Engineering Plastics in Europe. The pitch:  It has a relatively low density for a nylon, with good low-temperature impact resistance and has great dimensional stability due to its low water absorption.
At last June's National Plastics Exposition, two other companies announced availability of castor oil-derived nylons: DuPont and Evonik. DuPont's Zytel RS product family comprises all products based on nylon10/10 and nylon 6/10, including their copolymers and their alloys with other polymers. DuPont's nylon 10/10 contains 100 percent sebacic acid content while nylon 6/10 contains 63 percent. The proportions can vary for different applications.
Award Winner
The DuPont Zytel RS 6/10 was an award winner at last month's Society of Plastics Engineers Automotive design competition. Denso Corp. specified the castor-oil derived polymer in a radiator end tank in the 2010 Toyota Camry sedan. The requirements for the application were significant: exceptional heat resistance, durability and road salt resistance.
"Today's business climate - with demands for innovation in the face of intense cost pressures - is driving the engineering community to rethink the design and manufacture of automotive components and systems," says Patrick Ferronato, global director, development and marketing for DuPont Automotive Performance Materials. "It's challenging us all to use design and engineering strengths to the fullest and to drive ‘engineering strategy' beyond procurement price - at the end of the day, we must be cost-neutral at best, and collaboration for innovation is our best strategy to deliver economically and environmentally sustainable solutions."
Vestamid Terra is Evonik's brand name for its newly introduced polymers that are based partly or entirely from fatty acids. The most important source is currently castor oil. Vestamid Terra DS is a 100-percent bio-based nylon 10/10. Its property profile bridges the gap between high-performance long-chain nylons such as nylon 12 and nylon 12/12 and the shorter chain standard nylons 6 and 6/6. One particular target is glass-fiber-reinforced molding compounds. Vestamid Terra HS is a nylon 6/10 that contains approximately 60 percent renewable raw materials.
Evonik is also forging ahead with the development of further nylons from renewables based on palm kernel and rapeseed oils. On Nov. 30, Rhodia introduced its own castor oil-derived nylon,6/10.
Carbon Footprint
The big reason for the surge in castor oil nylons is reduction of the material's carbon footprint.
Rhodia's new nylon 6/10-based product line offers both high-performance, as well as economically attractive solutions that contribute to a reduced environmental footprint. The production of nylon 6/10, in part from castor oil, requires 20 percent less fossil fuels than a conventional nylon, while providing equivalent property performance.
The other argument for castor oil derivatives is that they do not come from human or animal food streams. Castor oil is also used to produce soaps, lubricants, hydraulic and brake fluids, paints, dyes, coatings, inks, waxes and polishes, pharmaceuticals and perfumes.
And long-term, it's hoped that bio-derived feedstocks may be less expensive than the highly volatile petrochemical feedstocks. At the least, it's hoped that the costs may be more predictable.
Editor's Note: Nylon, which was discovered in the 1930s by DuPont, is commonly called polyamide in Europe.