Nanomaterials have a long tradition at Degussa. The company already has several decades of experience with AEROSIL® fumed silica and AEROXIDE® fumed alumina and titania which were established long before the term nanotechnology was coined. This field reached new importance in the year 2000 with the opening of the Nanomaterials Project House, which was transferred, as scheduled, to the internal start-up Degussa and integrated into the Creavis Technologies & Innovation strategic unit on January 1, 2003. Advanced Nanomaterials has been part of the Aerosil & Silanes Business Unit since early 2005.
Over the past two years, the objective of the group has successfully been changed from a clear focus on research & development to a commercial, application oriented marketing of nanomaterials in various fields of application. For the effective marketing of products, Degussa has been presented with the “Leadership in Nanomaterials Award” by the Business Communications Company, Inc. (BCC) in the United States. Headquartered in Norwalk, Connecticut, the market research company estimates that the market for nanomaterials will continue to experience strong growth in the future.
Degussa has continually expanded the spectrum of powders and dispersions based on established and well-tested processes. The new pilot production plant in Hanau allows products to be supplied by the ton. Advanced Nanomaterials sees itself not only in the role of the material supplier, but as a partner who advises and supports its customers in solving their application problems. In rapid succession, Advanced Nanomaterials has also begun to launch zinc oxide, cerium oxide and indium tin oxide (ITO) on the market, under the brand name AdNano®. These materials are in the qualification phase for a broad range of attractive applications.
Figure 1. Beginning in 2007, a new reactor will increase the capacity for zinc oxide to several 100 metric tons annually
New Benchmark In Sun Protection
Nanostructured zinc oxide is a particularly effective UVA filter, which both absorbs and reflects these maximum intensity solar wavelengths. Zinc oxide has a host of advantages over traditional organic systems. Of these, long-term stability and high temperature resistance are the most important for paint and polymer applications.
Additionally, because of its nanostructure, zinc oxide is transparent to visible wavelengths, and it doesn’t leach out. Degussa’s initial offering includes two types of material: AdNano® ZnO 20 is hydrophilic and has a specific surface of more than 20 square meters per gram.
The primary particles have a size of 25 nanometers (nm) and form aggregates of 80 to 200 nm. AdNano® Z805 is modified on the surface with trimethoxy octyl silane to make it hydrophobic.
Degussa's initial marketing efforts will focus on application as a UV filter in both cosmetic products and coatings. Colleagues from the Personal Care Business Unit have already successfully completed the market launch in cosmetics, where the ultra-pure zinc oxide will be marketed under the trade name TEGO SUN Z 500 (hydrophilic zinc oxide) and TEGO SUN Z 800 (hydrophobic zinc oxide).
UV protection in coatings for industries such as furniture and construction is a large field of application. The key to the success of these types of systems is optimal dispersion of the particles. Degussa has vast expertise in this area through Tego Chemie Service GmbH in Essen, which develops and markets additives and specialty bonding agents for the paint and printing ink industries.
Figure 2. As little as 1 percent zinc oxide in paint ensures reliable UV protection for wood
Special interfacial phenomena play an important role in these products. The expertise gained in this area can now be used to develop complete dispersions with zinc oxide and offer solutions tailored to specific customer systems. Typically a formulation with 1 percent zinc oxide yields the desired UV protection for wood.
Zinc oxide is also attractive for producers of packaging, who are seeing a sharp rise in demand for solutions allowing for transparency. Currently, Degussa is cooperating with various large producers of PET bottles.
These increasingly sought-after containers are manufactured by extrusion-blow molding, in which temperatures can reach a maximum of 572 °F (300 °C). Large quantities of organic UV filters must be added to the polymer in order to compensate for the fact that much of it evaporates during the manufacturing process. By contrast, the zinc oxide remains stable and integrated in the polymer matrix under these conditions.
Long Processing Time, Fast Curing
The advantages of zinc oxide do not stop there: Polyurethane coatings with 2 percent zinc oxide are proven to be superior for reducing yellowing problems. Nanostructured multi-functional ingredients can even do the seemingly contradictory: When added to paints, the time available for processing increases, while the coating fully cures faster than with conventional systems.
Additional favorable characteristics are the higher final hardness and improved water repellency, which is achieved through hydrophobic adjustment. This allows less water to remain on coatings, resulting in less soiling of the surfaces.
The initial reactor for manufacture of zinc oxide in Hanau-Wolfgang was designed for a volume of metric tons per month. It has since been modified for two reasons: to increase production, and to achieve higher flexibility for the manufacture of various types of zinc oxide. Because demand for zinc oxide is likely to continue to grow, Degussa is planning to build a new reactor, scheduled to take up operation in 2007 and provide several hundred metric tons per year for the market.
The Finest Ceria Available Commercially
Degussa sees great market potential in the ultra-precise surface treatment of wafers for the integrated circuit industry. With chemical-mechanical planarization/polishing (CMP), the topographical unevenness of silicon oxide, polysilicon and metallic surfaces can be removed.
This prepares the layers for the subsequent lithographical deposition steps and prevents depth-of-focus problems during irradiation of the photosensitive surfaces.
Chips, whose structures are already in the nano-range, can therefore be made to be faster, smaller, and more efficient. With the size of electronic components continually shrinking, layers must be increasingly smooth.
This can be achieved through use of dispersions made of AEROSIL®, AEROXIDE® Alu C fumed alumina, and increasingly, cerium oxide (ceria).
Figure 3. Ceria is suitable for the ultra-precise surface preparation of wafers, which is a prerequisite for increasingly more powerful chips
An important step of CMP is shallow trench isolation (STI) technology. In STI, the silicon substrate is covered with a layer of silicon nitride, then structured and etched. CMP is used to remove all excess oxide from the top of the silicon nitride layer. Under the trade name AdNano® Ceria, Degussa manufactures the world’s finest cerium oxide, which allows the insulating layers and circuit paths of a microchip to be polished atomically smooth. This material is also now manufactured by the ton.
Production, which is scheduled to be transferred from the start-up Advanced Nanomaterials to the Aerosil & Silanes Business Unit at the beginning of 2007, is planned to be expanded by the addition of a new reactor at the Rheinfelden site.
The nano-structured cerium oxide combines a host of positive properties that make it an ideal material for CMP. These include a high rate of material removal, which is accompanied by a low defect rate and a highly planar surface. Additionally, the material provides high selectivity and high stability in dispersions. The size of the primary particles of AdNano® Ceria is below 10 nm, while the aggregates are less than 200 nm.
Nano-scale indium tin oxide by Degussa, or AdNano® ITO, also holds potential for providing substantial new business opportunities. The basis for various innovative applications for AdNano ITO is its transparency, combined with infrared radiation (IR) absorbency and electrical conductivity characteristics. These properties allow interesting applications such as films that reduce solar radiation in automobile windshields and the windows of buildings, thereby helping to conserve energy by reducing the need for air conditioning. The ITO particles can also be added to paints and coatings, which can enable an antistatic and highly transparent surface.
In the future, ITO layers will also be used for flexible or even rollable displays. Most of today's screens are still built on a rigid glass substrate, which is then sputter coated with indium tin oxide. But while these ITO layers have excellent electrical and optical properties, they have limited mechanical flexibility and are expensive to produce. In the future, the expensive deposition processes could be replaced by a simple printing process. ITO coatings give applications a large measure of design freedom, and also provide significant advantages in terms of scratch resistance.
Two and one half years after the start of Advanced Nanomaterials, the potential for success continues to accelerate: The new materials have been as well-received on the market as the problem-solving expertise which supports them. As part of the Aerosil & Silanes Business Unit, Advanced Nanomaterials is able to utilize the production infrastructure required for effective scale-up, expertise in applied technology, and excellent market access. For its part, Aerosil & Silanes profits from new products and advanced technologies, which will help sustain the innovative power and favourable market position of the business unit in the long term. The result combines the advantages of a small, flexible start-up with the strengths of an established business unit. In this sense, the conversion from former project house to operative business unit has been a success.