Rhenowave: Representative inline quality control for the production of black rubber compounds
Monday, 10. February 2014 Rhein Chemie is introducing Rhenowave, a new concept for controlling the quality of rubber compounds. The compounds are analyzed during extrusion (for example during straining or shaping) in a pulse transmission process with the help of ultrasound waves.
• Determining filler content, dispersion (> 10 µm) and distribution during extrusion
• Determining the distribution of Rhenogran AP (additive packages)
Rhein Chemie is introducing Rhenowave, a new concept for controlling the quality of rubber compounds. The compounds are analyzed during extrusion (for example during straining or shaping) in a pulse transmission process with the help of ultrasound waves. Nanoscale fillers such as carbon black and silica have particularly good damping properties for soundwaves in the range of 1 MHz to 20 MHz, so that the filler content can be determined with a precision of up to 1 phr. Unlike with many other analytical methods that use electromagnetic waves, carbon black does not disturb this process. As a result, even black compounds can be volumetrically analyzed. Owing to the sound scattering, large inhomogeneities (> 10 µm) can also be determined.
Using a marker with a high density, e.g. zinc oxide, the distribution of Rhenogran AP additionally can be monitored. Rhenogran AP products are customer-specific additive packages made from crosslinking chemicals, and are polymer-bound, dust-free and easily dispersible. Rhenowave is fast, both used alone or in combination with Rhenogran AP. Following the exit of the compound from the extruder, an assessment of the compound quality is performed within a few seconds (inline control). Where array technology is used, up to 100 percent of the compound can be analyzed. Small areas where compound quality is insufficient are recognized immediately rather than later in the product. The method is representative. With the aid of special ultrasound sensors, sensor distances of between 5 mm and max. 30 mm can be realized, depending on the compound and the compounding temperature T > 100 °C. This means that Rhenowave can be used in a production scale of 1,000 kg/h. Rhenowave is absolutely non-destructive.
On account of rising competitive pressure in the rubber processing industry, production processes are increasingly being accelerated to achieve higher productivity. “At the same time, the demands on the quality of rubber compounds also are on the rise,” says Dr. Andreas Schroeder, Innovation and Product Development, Rhein Chemie Rheinau GmbH. “To ensure low reject rates even under these conditions, the content, dispersion and distribution of the fillers, and the crosslinking chemicals must be evaluated rapidly and in representative fashion,” he adds.
Today, rubber compounds usually are characterized by their Mooney viscosities and their crosslinking and tensile stress elongation curves.These tests are destructive, meaning that only a very small percentage of the rubber compound < 0.1 % is tested. This kind of sampling therefore is not representative, but rather random. Areas displaying inadequate compound quality frequently are not detected. In addition, quality control is carried out offline, minutes, hours or even days after the compound is manufactured. As a result, errors in the compounding process are not identified until a late stage, let alone eliminated, so that in the worst case scenario rejects continue to be produced.
About Rhein Chemie
Rhein Chemie develops, produces and sells additives, specialty chemicals and service products for the rubber, lubricant and plastics industries. In fiscal 2012 Rhein Chemie achieved sales of EUR 344 million and has approximately 1,100 employees worldwide. The company is headquartered in Mannheim, Germany and has production facilities in Europe, Asia and North and South America. Rhein Chemie is a wholly owned subsidiary of the specialty chemicals group LANXESS, Cologne, Germany.
Mannheim, 10. February 2014
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