New Nd-BR Grade Enables Eco-Friendly Tyres

Specialty chemicals group Lanxess AG is extending its range of highly elastic neodymium-polybutadiene (Nd-BR) rubbers with a grade of particularly high viscosity – Buna CB 21. This product, whose Mooney viscosity of 73 MU is unique among commercially available grades in this rubber family, features outstanding rebound resilience and particularly low heat buildup, making Buna CB 21 an ideal product for cutting the rolling resistance of car tires–which saves fuel consumption.The reduction in fuel consumption, in turn, cuts down the discharge of CO2 and lowers the impact on the environment. This is a key feature of great significance, particularly with respect to the efficiency labeling of tires that has already been mandated by the European Parliament.

Dr. Thomas Gross, rubber expert at Lanxess’ Performance Butadiene Rubbers business unit, said:

Buna CB 21 enables us to meet the pressing need of many of our customers for a synthetic rubber with particularly good rebound resilience. After the positive feedback from the sampling for our trial product, we are now also ‘officially’ incorporating this rubber into our range. We are especially pleased that this coincides with the centenary of synthetic rubber and naturally we hope that Buna CB 21 will be one of the successes of the century.

The rebound resilience of a rubber – closely linked to heat buildup under stress – is critical for rubber products subjected to dynamic loads. It is an indication of how economically an elastomer uses energy during deformation. High rebound resilience indicates that a rubber transfers a large proportion of the mechanical energy that is introduced, or releases this after loading, without converting it into heat and therefore wasting it.

Rubber molecules that are as long as possible and have a uniform length/molecular weight are ideal for high rebound values. This makes a material of this type suitable for achieving a further significant decrease in tire rolling resistance – essentially the proportion of drive energy converted into heat by rolling as a result of inevitable deformation – compared to products filled with silica.

Gross says:

Thanks to our advanced production technology, our Nd-BR elastomers feature a particularly narrow molecular weight distribution. As a result, they contain relatively low proportions of lightweight plasticizing and heavy viscosity-enhancing molecules. We therefore don’t need to sacrifice good rebound values for solution viscosity levels that are too high. This enables us to bring onto the market a neodymium polybutadiene, Buna CB 21, that offers unique rebound resilience levels and extremely low heat buildup.

The new elastomer is initially being produced for the worldwide market at the Dormagen site. Further Lanxess production facilities such as those at Port Jérôme, France, and Orange, United States, also have the technical capability to manufacture the product and can be called upon if necessary.◊

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