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Leverkusen, Germany, 2010/10/27 - Fully automated coffee machines that make fresh cappuccino, caffè latte, espresso and other specialty drinks by the cup using pads and capsules have long since replaced the plain old coffee pot in many companies and households. FRA: DE Frankfurt: LXS
And it is highly likely that, while indulging in their passion, coffee lovers are benefiting from an inconspicuous component of these machines that is made of the high-performance LANXESS elastomer Therban. A rubber seal measuring just under five centimeters developed by seal specialist Eriks GmbH (Bielefeld) for a major component supplier ensures that pressurized coffee machines stay tightly sealed at the crucial point. The HNBR elastomer Therban triumphed over many competitors such as EPDM and fluororubbers for use in this application.
Demand for espresso and coffee made using pads and capsules is extremely high at the moment. According to the German Coffee Association in Hamburg, sales of pad and capsule systems increased by around 15 percent in Germany alone in 2009. Consumption of individual portions of coffee has risen ten-fold since 2004, with consumers attaching more importance to lifestyle, convenience and quality. This is reflected in the success of fully automated coffee machines that specialize in such portions. “These are highly complex devices with sophisticated mechanics and electronics,” explained Oliver Lips, head of Applications Advice and Sales in the Eriks sealing technology division.
The rubber components have specific challenges to master. “All seals must be made of materials that not only meet food regulations – at least FDA-compliant according to 21 CFR 177.2600,” said Lips, “but are also resistant to a variety of media. Most sealing elements come into contact with oils from coffee beans or with milk fat and have to withstand contact with cleaning products, descalers and hot steam. Modern machines press boiling water through the powder at pressures of up to 16 bar.”
This exceeds the capabilities of many rubber materials. “Non-polar, saturated rubbers such as EPDM are resistant to steam, but not fat. By contrast, standard fluoroelastomers withstand contact with cleaning products and oils, but not long-term steam exposure. Special steam-resistant grades are available, but they are usually expensive,” added Lips. The HNBR elastomer Therban, on the other hand, combines good resistance to the above challenges with an attractive price, according to the sealing expert. “Because it contains polar nitrile monomers, Therban is actually well protected against swelling in non-polar media,” confirmed Dr. Andreas Bischoff from the LANXESS Center of Excellence for Therban who advises his customers on all aspects of this versatile high-performance elastomer. “And due to its saturated molecular backbone, the elastomer also exhibits longer-lasting protection against aggressive cleaning products and premature aging under the high temperatures of pressurized steam.”
The Therban seal must also overcome considerable mechanical challenges. Each of the many times that the pad or capsule carrier is sealed, the component must travel a substantial distance and must always be free of dead space for hygiene reasons. What’s more, steam must not escape from the machine under any circumstances. “It is therefore very important for the sealing material to maintain its good dynamic properties over a long period, even at high operating temperatures,” said Oliver Lips. Here, too, Therban outshines fluoroelastomers.
“The design of the seal must also be tailored to the intended use,” added Lips. Eriks therefore actively supported the customer in both selecting the optimal material and designing the sealing element.
LANXESS (lanxess.com) is a leading specialty chemicals company with sales of EUR 5.06 billion in 2009 and currently around 14,400 employees in 23 countries. The company is represented at 42 production sites worldwide. The core business of LANXESS is the development, manufacturing and marketing of plastics, rubber, intermediates and specialty chemicals.