One of the hottest stories in engineering plastics now isactually one of the oldest - nylons made from renewable resources.
Nylon 11 derived from castor oil was first developed bychemists at IG Farben in Germany in the 1940sin a drive to make fuels and industrial products from sources other thanpetroleum. The rights were acquired by an American chemical producer afterWorld War II and later sold to Elf Aquitainein France, which successfully commercializedthe material as Rilsan 11. It gained a market niche based on its uniqueproperty profile - and nothing to do with its environmental friendliness.
Rilsan 11 has been widely used for automotive applicationssuch as fuel line tubing, particularly in Europe,because of its combination of chemical resistance and good mechanicalproperties. Elf Aquitaine is now part ofArkema, which has expanded the product line.
At K 2007, BASF, whose chemists working for Farben haddeveloped the first castor nylon, announced introduction ofUltramid Balance nylon 6/10, which is about 60 percent based on sebacic acid, amaterial derived from castor oil.
"We have woken it up from a long sleep because the subjectof renewable raw materials has become important to our customers," says KurtHoefli, head of marketing for BASF's Engineering Plastics in Europe.The pitch: It has a relatively lowdensity for a nylon, with good low-temperature impact resistance and has greatdimensional stability due to its low water absorption.
At last June's National Plastics Exposition, two othercompanies announced availability of castor oil-derived nylons: DuPontand Evonik. DuPont's Zytel RS product family comprises all products based onnylon10/10 and nylon 6/10, including their copolymers and their alloys withother polymers. DuPont's nylon 10/10 contains 100 percent sebacic acid contentwhile nylon 6/10 contains 63 percent. The proportions can vary for differentapplications.
Award Winner
The DuPont Zytel RS 6/10 was an award winner at last month'sSociety of Plastics Engineers Automotive design competition.Denso Corp. specified the castor-oil derived polymer in a radiator end tank inthe 2010 Toyota Camry sedan. The requirements for the application weresignificant: exceptional heat resistance, durability and road salt resistance.
"Today's business climate - with demands for innovation inthe face of intense cost pressures - is driving the engineering community torethink the design and manufacture of automotive components and systems," saysPatrick Ferronato, global director, development and marketing for DuPontAutomotive Performance Materials. "It's challenging us all to use design andengineering strengths to the fullest and to drive a euro ~engineering strategy' beyondprocurement price - at the end of the day, we must be cost-neutral at best, andcollaboration for innovation is our best strategy to deliver economically andenvironmentally sustainable solutions."
Vestamid Terra is Evonik's brand name for its newlyintroduced polymers that are based partly or entirely from fatty acids. Themost important source is currently castor oil. Vestamid Terra DS is a100-percent bio-based nylon 10/10. Its property profile bridges the gap betweenhigh-performance long-chain nylons such as nylon 12 and nylon 12/12 and theshorter chain standard nylons 6 and 6/6. One particular target isglass-fiber-reinforced molding compounds. Vestamid Terra HS is a nylon 6/10that contains approximately 60 percent renewable raw materials.
Evonik is also forging ahead with the development of furthernylons 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 isreduction of the material's carbon footprint.
Rhodia's new nylon 6/10-based product line offers bothhigh-performance, as well as economically attractive solutions that contributeto a reduced environmental footprint. The production of nylon 6/10, in partfrom castor oil, requires 20 percent less fossil fuels than a conventionalnylon, while providing equivalent property performance.
The other argument for castor oil derivatives is that theydo not come from human or animal food streams. Castor oil is also used toproduce 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 beless 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.

Renewable Nylon Applications Start to Surge A