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- Patents
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The role of research and development at Rhenotherm
We acquired our knowledge of fluoropolymers from the inventor of Teflon® - DuPont de Nemours. Over years, this well-founded knowledge was continually advanced. We continue to use our international experiences and contacts for this purpose.
In 1981
Rhenotherm was the first company in Europe that brought commercially available ETFE coatings on the market.
1984 Patent Stadtwerke [public utility company]
Rhenotherm developed a system consisting of a combination of fluoropolymers and an inorganic primary layer, with the primary layer operating according to the sacrificial anode principle. This system was developed specifically for flue gas desulfurization systems and was patented in 1985.
In 1985 / 1986
we developed our systems Jumbo I + II in cooperation with the company Hoechst and had them patented. In this context, we conducted research on a thick film version of fluoropolymers for use in the chemical industry. Thick film systems are based on fluorothermoplasts that are applied in several layers. At a certain point, the circumvention of physics is no longer possible, and gravity causes the layers to run off. In order to prevent this, we combine the polymers PFA and FEP. Both are suited for highest chemical demands and high temperatures. The idea is simple: PFA with a melting point of 307 – 310°C is applied as primary layer. Subsequently, the fluorothermoplast FEP – melting point 270°C – is used for further processing. When the FEP layer is sinter-fused, the PFA layer is no longer liquid and therefore cannot run off.
1986
Our laboratories continued their research:
- chemical resistances
- We used a cold finger to test different coatings for use in the chemical industry
In the process, we noticed the following phenomenon:
- Stress crack
A stress crack in the surface layer, caused by exposure to chemicals, is stopped by the carbon fiber reinforcement of the undercoating. Based on this discovery, we developed a system that features varying compounds.
As a result, in 1999,
- Jumbo III layers
we filed a patent application for Jumbo III. This patent (granted in 2002) is based on the Jumbo II system, which features a variety of filler materials. Different compounds fulfill different functions. For example, tensile stress in concrete is transferred using steel reinforcements. The same effect is achieved through the use of carbon fibers in the Jumbo III system. Embedded glass flakes extend the permeation distance. A similar effect is created by incorporating special pigments into fluoropolymers. This combination leads to our Jumbo III system.
- Jumbo II coating
- Comparison of filler materials
The picture on the right shows that the Jumbo III system achieves an improvement by a factor of 3 regarding permeation and diffusion, compared to an unfilled system. Permeation and diffusion are a function of partial pressure, which in turn is dependent on the increase in temperature during the application.
We distinguish between three different temperature situations:
a) Isotherm state: Diffusion is not of significance here, which means the service temperature can be relatively high.
b) Working temperature up to 120°C: We recommend our Jumbo II system, provided the medium is not highly diffusible.
c) Working temperature up to 160°C: We definitely recommend our Jumbo III system.
In all cases, it is necessary to know the exact operating conditions. In some cases, the application may have to be tested on samples. A corresponding design of the parts’ structural characteristics is equally important. We would be happy to advise you in these cases.
In the 1990s, Professor Dr. Barthlott studied and publicized the so-called lotus effect, which is widely known today. Those findings led to the development of our system called “Lotuflon” in 1998, for which we filed a patent application in 1999.
This system is based on the structural design of the lotus leaf.
- Lotus SEM
- Lotuflon SEM
We developed a double structure system.
A combination of a metallic or ceramic base structure with coating by a fluoropolymer that possesses a substructure.
2003
we obtained the patent.
The effect of such systems is measured using a water contact angle.
- Measuring the water contact angle
- Lady’s mantle leaf with water drops
We achieved roughly 145° with our Lotuflon system. The lotus leaf possesses an angle of 162°. The water contact angle of PTFE is roughly 110°.
2004
We participated in a research project on non-adhesive surfaces on the basis of tetraether lipid-coated metals. The project, backed by the German Bundesministerium für Bildung und Forschung [Federal Ministry for Education and Research], was a cooperation with the TU (Technische Universität) [technical university] Dresden (project management), the University of Halle, the IBA (Institut für Bioprozess- und Analysenmesstechnik) [Institute for Bioprocessing and Analytical Measurement Techniques] Heiligenstadt, and the company Nehlsen-BWB.
In the course of this research project, we acquired a high-resolution scanning electron microscope (SEM) with integrated backscattered electron detector (BSE detector) to illustrate material contrast, which may also be made available for externally processed orders.
- Scanning electron microscope (SEM)
- SEM micrograph: flame spray coating taken with two detectors
Since 2006,
we have been working with the Portuguese job coater Flupol LDA on the development of primer systems to replace the so-called chromium(VI) primers.
2007
Together with the TU Dresden and the company Flugzeuggalvanik Dresden, we are working on another government-backed research project, which will continue into the year 2010. The goal of this project is the creation of permanently textured, non-adhesive surfaces. As part of the project, a contact angle measuring system was purchased in order to better distinguish between structural differences where quality variations can no longer be made out with the naked eye. As evident in the picture, extremely high contact angles can now be determined more accurately.
