Tough Auto Requirements Drive Fluoroelastomers Growth

Automotive applications dominate consumption of fluoroelastomers, and vehicle trends are fostering greater fluoroelastomer use. Material producers are launching tailored grades to make the most of the opportunity. “Most fluoroelastomers are used in applications where no other material can perform,” says John Scheirs, principal consultant at ExcelPlas Polymer Technology and Testing, Edithvale, Australia.

They stand up to a wide range of chemicals and can cope with temperatures of 250°C. This performance comes at a premium price, though, from around $20/lb for standard grades to $50/lb or more for some specialties.

So, even as automakers try to trim vehicle costs, they increasingly rely on high-priced but high-performance fluoroelastomers for critical seals, O-rings, and other components.

Changes under the hood are a key driver. Engines are running hotter. Some shaft seals and valve-stem seals now must work for long periods at 200°C, and intermittently handle temperatures up to 270°C, notes Scheirs. Con-sumers are demanding longer intervals between regular maintenance, such as oil changes; oils now contain alkali amine additives that extend fluid life but attack elastomers including standard fluoroelastomers. Other automotive fluids are expected to last the life of the vehicle. “‘Filled for life’ means ‘sealed for life,’” notes Dan Doolan, senior consultant at BRG Townsend, Mt. Olive, nj. And some carmakers now offer up-to-10-yr warranties, and so opt for durable fluoroelastomers to minimize claims.

Environmental regulations also play an important role, particularly in the U.S., notes Howard Blum, director at Kline & Co., Little Falls, nj. For instance, the California Air Resources Board’s LEV II rules, which go into effect in 2004, limit overall evaporative emissions from a vehicle to 0.5 g/24 h. This is spurring conversion of fuel-system seals and engine gaskets to fluoroelastomers, says Bob Grinwis, North America business manager for Solvay Solexis, Thorofare, nj, which was formed after Solvay purchased Ausimont. Air-intake-manifold gaskets are being switched from silicone to far-less-permeable fluoroelastomers, notes Bob Bernacki, Viton global business director for DuPont Dow Elastomers, Wilmington, de.

In addition, the increasing use of gasoline containing oxygenates (such as mtbe) that are tough on seals is fueling a move to specialty fluoroelastomers for components like fuel-injector O-rings.

A small, growing and changing market

Leading suppliers and market researchers estimate 2002 global fluoroelastomers consumption at 30 to 35 million lb, worth $400 million to $500 million. North America accounts for about 50% of demand, followed by Europe and then Japan. Automotive applications represent more than half of the global market.

Grinwis, Bernacki, and other observers expect worldwide volume growth of 3 to 5%/yr for the next few years. Demand for more expensive specialty fluoroelastomers — base-resistant, low-temperature, and peroxide-curing grades — should increase at double that rate.

Specialty fluoroelastomers, which now account for around 16% of the global market, should reach 25% by 2010 or sooner, says Bernacki. Grinwis wouldn’t be surprised if they represent around 40% of the market in five years.

At least 80% of fluoroelastomers now are molded, says Bernacki, with injection molding gaining favor over compression molding. It already represents half of production in Europe, he notes, and is rising in North America. A couple of materials makers also see a role for liquid injection molding (lim).

New technology transforms grade slates

DuPont Dow in July started up a plant in Dordrecht, the Netherlands, that inaugurates its Advanced Polymer Architecture (apa) process. The technique allows more precise control of molecular-weight distribution, branching, and chain-end configuration, while a new cure-site monomer provides faster and cleaner crosslinking. The company is upgrading its Viton line with “S” versions made via the apa process.

The new grades provide parts with superior compression-set resistance and sealability, greater resistance to stretching during automated assembly, lower water swell, and better acid resistance, without compromising heat resistance. They also mold and extrude better, cure faster, demold easier, and foul molds less. The new grades also promise to cut or eliminate postcure. They cost about 10% more than conventional versions, which remain on the market.

Also in July, Solvay Solexis brought onstream at Thorofare its first North American production unit for fluoroelastomers, a plant pioneering its High Stability process. The plant now is producing four Technoflon HS grades, and should add another two during 2003, says Grinwis. The materials offer the same low compression set as conventional grades, but require only a 1-h postcure instead of 12 to 24 h.

Solvay Solexis is utilizing proprietary peroxide-cure technology for low-temperature and base-resistant materials. It introduced in 2002 Technoflon PL 557, which provides a 50% improvement in permeation resistance at -30°C compared to previous grades, says Grinwis, for a slight premium in price. The company may debut by mid-year a base-resistant material that can handle about 15°C-lower temperatures.

The company also hopes to launch this year a material that incorporates nanoparticle ptfe. The grade overcomes the processing difficulties usually encountered with ptfe filler, says Grinwis. It is easy to mold and extrude, and improves permeation resistance by 50% compared to 70%-fluorine peroxide-cured materials containing mineral or carbon-black fillers, he adds.

Daikin, Osaka, Japan, will use new technology at a plant in Pierre-Benite, France, slated for start-up in early 2003.

The company is developing new chemistry for bisphenol grades, and is fine-tuning the technology for its peroxide-cured materials, says Bob Dixon, business manager for fluoroelastomers at Daikin America, Orangeburg, ny. It recently launched a grade targeted at meeting LEV II permeation standards at low temperatures. The company also hopes to have a lim grade on the market by the end of 2003.

In late November, Dyneon, Oakdale, mn, introduced MIP 8640X, the first of a family of products based on the company’s proprietary Multifunctional Improved Processing technology. The grade reportedly provides faster curing, superior compression-set resistance, and more versatility during processing. A higher-viscosity material, it nevertheless boasts better flow properties than conventional grades. MIP 8640X also is said to give smoother, higher-quality surfaces and increased hot-tear strength, while maintaining excellent dimensional stability.

The company also is developing a new class of high-performance, low-temperature fluoroelastomers, notes spokesman Doug Chirhart.

Meanwhile, Asahi Glass Fluoropolymers, Tokyo, has introduced Aflas SZ and SP base-resistant grades. They offer easier processing and less mold fouling, notes Evan Laganis, business and market development manager for Asahi Glass Fluoropolymers U.S.A., in Chadds Ford, pa. The materials rely on undisclosed, proprietary technology. The company also is working on grades suitable for lower temperatures.

Shin-Etsu Silicones, Tokyo, sees promise in lim, says Columbia, sc-based Claude McClure, national sales and marketing manager for Shin-Etsu Silicones of America. He notes that Sifel lim grades require 1 min or less of press cure at 150°C, and 4 h of postcure at 200°C, far shorter times than those typical for injection molding. The fluoroelastomer comes in hardnesses from 40 to 70 Shore A. Sifel maintains flexibility to -50°C and is base-resistant. The company hopes to debut, in the second half of this year, a peroxide-cure grade that has greater chemical resistance.