Canadian Plastics

DuPont Sorona grows beyond apparel

By Rebecca Reid, managing editor   



Next time you're at the beach and you're caught ogling an attractive member of the opposite sex, you can easily cover for your wandering eyes by asking: "Is your swimsuit made from Sorona ?"...

Next time you’re at the beach and you’re caught ogling an attractive member of the opposite sex, you can easily cover for your wandering eyes by asking: “Is your swimsuit made from Sorona ?”

Since its commercial debut in 2002, DuPont Engineering Polymer’s Sorona 3GT fibre — which is made with Bio-PDO, derived from fermented corn sugar — has been used to weave fabric for bathing suits, outerwear and even underwear.

But this was only the first step in DuPont’s quest to reduce its dependence on petrochemical products. At the National Plastics Exhibition (NPE) 2006 in June in Chicago, the company announced that in 2007 plastics processors would have access to two engineered resins manufactured with Bio-PDO.

A new grade of Sorona as well as a thermoplastic elastomer sold under the firm’s Hytrel name, dubbed Hytrel made with renewable resources, will both incorporate Bio-PDO.

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For Sorona, Bio-PDO replaces 1,3 propane diol (PDO) and/or 1,4-butanediol (BDO), which is reacted with terephthalic acid, Nandan Rao, vice-president of technology for DuPont Performance Materials, explained. The result is a polymer comprised of 37 per cent renewable resources that processes and has properties similar to polybutylene terephthalate (PBT).

These include good strength, stiffness, surface appearance, glossiness and good dimensional stability. Target applications include automotive parts and components, electrical and electronics systems as well as industrial consumer products, he added. It will be commercially available by mid-2007.

Dupont’s Hytrel made with renewable resources , which will be available in the fourth quarter of 2007, is a two-phase thermoplastic polyester elastomer consisting of hard segments and soft segments. The soft-segments are made from a Bio-PDO-based polyol replacement and will comprise between 40 to 60 per cent of the resin, Rao said.

Improvements over current Hytrel include an increased temperature range and better elastic recovery, he noted.

Potential applications include extruded hose and tube automobile components, blow-molded boots for automotive constant-velocity joints, and injection molded parts like air bag doors and energy dampers. Hytrel will be available by the fourth quarter of 2007.

GENETIC ENGINEERING

The key ingredient to these new resins, Bio-PDO, is mass-manufactured by a genetically engineered micro-organism developed by DuPont and biotechnology firm, Genencor International, based in Palo Alto, Calif.

“We’ve long known about micro-organisms that convert glucose to glycerol, or glycerol to 1,3 propane diol — called PDO for short. [But] there was no single organism that did both,” Rao said.

This genetically engineered micro-organism is now part of the Bio-PDO manufacturing process, and is a technically tiny but key part of DuPont’s goal to derive 25 per cent of its revenue by non-depletable resources by 2010, Rao said. That’s because Bio-PDO can be manufactured using 40 per cent less energy than its petrochemical counterpart. If DuPont produces 100 million pounds of Bio-PD0 a year, as per its plan, it stands to save 10 million gallons of gasoline per year.

Production of Bio-PDO is scheduled to begin in late 2006 at a new facility in Loudon, Tenn., owned and operated by a joint venture between DuPont and Tate & Lyle BioProducts LLC.

Yet one question remains: In its new era of corporate responsibility, will DuPont pledge to keep Sorona fibre a secret from the manufacturers of men’s bathing suit briefs?

E.I. du Pont Canada Co. – Engineering Polymers Division (Mississauga, Ont.); (905) 821-5953; www.plastics.dupont.com; www.sorona.dupont.com

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