Dec 15 2005
Polyurethane flexible molded foams from Bayer MaterialScience AG have been used for years in vehicle interiors as an effective means of reducing noise. Located in the bulkhead cladding or under the carpet, they absorb solid- and air-borne noise. Bayer’s experts have now developed flame-resistant grades of the flexible molded foam Bayfit® Tec specially for the electrical industry. This innovation ensures noise reduction for high-end vacuum cleaners, dishwashers and other electrical devices.
"Unlike conventional insulating mats, polyurethane molded foams fill spaces exactly, even those with complex geometries. This enables them to absorb sound extremely effectively," explains Alfred Schulz of Bayer MaterialScience, an expert on Bayfit® foam systems. The foams can also be chemically adjusted so that they stick fast to the surrounding materials and do not slip even when subjected to severe vibrations. The result is very good vibration absorption. With the new grades of foam, the housing and engine of an electrical device, for example, can be largely separated from each other acoustically.
The flame-retardant properties of materials used in electrical devices are subject to particularly demanding requirements. "The new Bayfit® Tec grades for the electrical industry conform to HF-1 or HBF (HBF is the highest possible classification) according to the strict US fire safety standard UL 94," says Schulz. This test includes checking whether and how fast a foam test piece burns when it has been exposed to a naked flame for a minute and whether material dripping from the test piece due to heat ignites a layer of cotton wadding. The flame-retardant properties of Bayfit® Tec depend on special polyols containing finely dispersed polyurea. Its key benefit is the fact that the extremely finely distributed polyurea particles do not settle out. They exhibit stable sedimentation properties and therefore ensure consistent product quality. This also allows high fire classifications without the addition of halogenated flame retardants.
Bayfit® Tec can easily be combined with other materials e.g. heavy layers.
Cables and insert parts can be insert molded and thus fixed in position.
The sound-absorbent foams open up almost unlimited possibilities for designers, including even complex three-dimensional forms with sharp variations in thickness and long flow paths.