Major US plastics producers are unveiling a full palette of “green” engineering plastics that run the gamut from corn-based to flame-retardant systems based on nonhalogenated materials and low-emission plastics for use in auto interiors.
DuPont Engineering Polymers reviewed its plans for environmental and other areas in exclusive briefings with Design News at their corporate headquarters in Wilmington, DE. Many of the plans relate to announcements made in conjunction with K 2007, the giant German plastics show, which will be held in Düsseldorf, Germany in mid-October. Separately, GE Plastics announced a new suite of nonhalogenated resin packages in a press conference on June 6.
The biggest bet is coming on biobased feedstocks that will be sold as high-strength polyesters and elastomers. “We believe the biological process can fully compete with the petrochemical route to plastic building blocks,” says Nandan Rao, technology director for DuPont high-performance materials. Biobased engineering plastics are in the beta testing stage and will be announced later this year.
It was disclosed in the briefing that the biobased elastomer may go to market as a consumer product, specifically as a polymer used in an engineered “breathable” film used in fabrics for outdoor wear. “People can see the value in this kind of product,” says Thomas Oury, DuPont’s business manager, Flexible Solutions - Americas. “DuPont Active Layer is a recyclable product. And it is already getting a huge market interest because of this feature. The recent work of DuPont in biobased materials is likely to open ways for us to develop and market a renewable resource-based DuPont Active Layer. But this is a longer term perspective, and at this stage it is too early to say when this will be available in the market.” Another major application for this material is surgical gowns.
Elastomers Versus Rubber
The recyclability of thermoplastic elastomers in general is a growing marketing pitch in applications where they compete against thermoset rubber.
Thermoplastic elastomers are more expensive than rubbers, but costs can be reduced through part integration and faster processing times. One of the DuPont announcements is the opening of a new multilayer extrusion line at its European Technical Center in Geneva, Switzerland, to expand elastomer applications. In one prototype application, a multilayer coolant pipe is extruded in nylon and adhesive as a replacement for rubber. The nylon provides mechanical stability while the inner layer of adhesive resin reduces permeability.
Another development is new grades of polyacetal which meet interior emission standards originating in Europe. New grades of Delrin reduce emissions by about 90 percent . Typical applications are gears for drives and actuators, window-lift systems, door-lock housings, safety-belt guides, and various knobs and push buttons. Kathleen P. Schodt, technical consultant to the Delrin business, said the tougher interior emission standards are expected to migrate to the United States.
Also new, and particularly important for electrical/electronic products sold in Europe, are new halogen-free V0 grades that eliminate brominated materials. The new new compounds that are halogen free, Zytel nyon and Rynite polyester, are V0 at 0.8 m. The Glow-Wire Ignitability Temperature of Rynite RE19041 is 775°C. Target applications for the Rynite are in printers, lamp sockets, and electronic components.
“Sustainabilty” is one of the major goals outlined by Timothy P. McCann, DuPont’s’ vice president of sales and marketing for engineering polymers. Other goals are lightweighting and reduced automotive emissions, automotive safety, improved product performance, and the trend toward what McCann described as human connectivity, or the explosion in products like cell phones, personal digital assistants and laptops.
GE Plastics announced a new halogen-free portfolio of its Starflam products aimed at electrical and electronics products. “Many different industries face increasingly stringent environmental requirements on the use of halogenated flame retardants,” said Nitin Apte, general manager of the LNP compounding unit of GE Plastics. “Until now there were no good alternatives to traditional reinforced polyamides.”
One of the early users is Winchester Elecronics, Wallingford, CT, which was looking for a material that could be used for surface mounting of connectors on to printed circuit boards. The process had to meet lead-free and halogen-free requirements. Winchester is using Starflam UF-1006 HW 227, a high-temperature nylon with 30 percent glass fiber reinforcement. It replaces a polybutylene terephthalate (PBT) resin.
The new flame retardant chemistries at DuPont and GE Plastics are proprietary.
GE Plastics also announced new Stat-Loy alloy compounds that have low volatile organic compound (VOC) outgassing and low leachable ions. Stat-Loy compounds combine an insulative base resin with an inherently conductive polymer to provide permanent anti-static performance.