German public-private partnership
creates easy-cleaning nano coating

BERLIN, Aug. 21, 2002 — Do you weep when dirt and calcium deposits dull those shiny chrome fixtures in your bathroom or kitchen? Do you wince when cleaning supplies leave your chrome glittering, but your hands red and chafed? All that could be a thing of the past.

That language might sound straight out of a 1950s women’s magazine, but the product, a chrome surface that repels water and dirt and makes cleanup a snap, is very much a 21st century development. It has been made possible thanks to a nanoparticle coating and a fruitful collaboration between public research and private industry.

One of the private parts of the equation, and the driving force behind the cleaner chrome, is Hansa Metallwerke, a kitchen and bathroom fixtures company based in Stuttgart, Germany, with operations in Europe and North America and annual gross revenue of $263 million.

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According to Michael Lutscher, head of product management at Hansa, the company was having problems with aggressive cleaning agents damaging chrome surfaces, especially in industrial use. Hansa wanted to coat those surfaces so that they would require little or no cleaning.

“We had heard about a technology called Sol-Gel making glass scratch resistant and we wanted to try it on chrome,” he said.

Problem was, it had never been done before and Hansa, while knowing a lot about manufacturing, didn’t know much about Sol-Gel. The company decided to use its connections with the University of Stuttgart and other related research institutions to look for partners that could turn its idea into reality.

It found them in the publicly funded Fraunhofer Institute for Production Technology and Automation (IPA) in Stuttgart and FEW Chemicals, based in the town of Wolfen.

“We divided up the duties clearly, putting the scientific knowledge of Fraunhofer and FEW in synch with our practical experience in industry,” said Hansa’s Lutscher.

FEW Chemicals joined the team because of its expertise in Sol-Gel technology. In the Sol-Gel process, aqueous/organic solutions (sols) of nanoscale Polysiloxane particles are generated. These inorganic/organic materials have several important advantages over conventional coatings. They are harder, more solvent resistant and less sensitive to heat, even when applied in layers of just a few microns in thickness.

The nanoparticles, which link to take on a net-like form, are “doped” with fluorine molecules. This makes them water resistant, since the contact areas between the water and the surface becomes much smaller. Calcium or dirt may remain behind after the water pearls off, but the Sol-Gel coating keeps even that from strongly adhering to the surface. Just a wipe with a rag and it’s clean.

That still left the challenge of getting the nanoparticle-infused coating to stick to a smooth chrome surface, which was IPA’s task. It solved the problem by developing a new treatment method for the metal. For the first time, a Sol-Gel coating could be applied to chrome, and it would stick.

“Our new coating works on a different principle than the so-called lotus effect,” said IPA’s Siegfried Berg, referring to the self-cleaning properties of rough surfaces, even though that roughness may be at the nanolevel. “We decided to address the problem from a chemical standpoint instead of changing the structure of the surface.”

In doing so, they avoided the problem of extreme surface fragility — the main hurdle to getting products based on the lotus effect to market.

Hansa, for its part, wasn’t interested in spending years on research. It had very practical reasons for developing the new fixtures: It wanted a product it could sell.

“In our industry, the market in saturated,” said Lutschert. “Right now we’re seeing companies in the fixtures business being driven out of the market. If you don’t come up with innovations, you’re going to follow them.”

He said the new chrome product line, which is in its final testing phases and should appear at trade shows in the spring, will bring the company a step forward both commercially and technologically. He said he has his partners to thank for that.

Such private-public partnerships are becoming more common in the world of German nanotech, according to Jochen Dressen, nanotechnology expert with the German Engineering Association. They are even actively encouraged by the German government’s nanotechnology initiative.

“Not only do you have a stronger team when people with different abilities come together,” he said, “but often working with industry can prove to be a motivating force for research institutions, who are used to mainly creating a lot of paper. But now they see their research actually turned into something.”


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