LOW ROLLING resistance tyres make for lesser carbon emissions on the roads. Lanxess, Germany’s synthetic rubber producer and world’s largest manufacturer of NdPBR (neodymium polybutadiene), has made the processing of such energy-efficient tyres even easier with its newly launched NdPBR rubber grades.
Buna Nd 22 EZ and Buna Nd 24 EZ are characterised by high molar masses necessary to fabricate tyres with outstanding low rolling resistance, but are still exceptionally easy to process due to the new Lanxess rubber modification technology. Hence these new modified Nd-PBR grades represent attractive alternatives for the high performance Nd-PBR Buna CB22 and Buna CB24 rubbers already widely applied in the tyre industry. Both grades are now available in sample- and industrial size quantities.
“Within the last years, energy efficiency without negative influence on other properties has become one of the main issues in the tyre industry,“ says Kim Joo Sang, Head of the Performance Butadiene Rubbers business unit for the Asia-Pacific region at Lanxess, “as the transport sector is responsible for about 22% of carbon dioxide emissions globally, and about 15% in Singapore. However, energy-saving tyres can help to reduce CO2 emissions on our roads substantially, especially since our Nd-PBR rubbers are recognised as a key-enabler for the production of high performance tyres with a low rolling resistance and therefore reduced fuel consumption leading to less emissions.“
One of the key properties of these rubbers is their narrow polydispersity, which leads to higher molar mass. “The higher a rubber’s molar mass, the lower can be the trye‘s rolling resistance,” explains Kim. “So, high molecular weight Nd-PBR is superior to other PBR types with broader polydispersity in key properties such as rolling resistance and abrasion. However, high molar masses until now were correlated with high-Mooney viscosities, presenting a crucial hurdle to overcome in order to get the best performance out of regular high performance Nd-PBR rubbers. The processability of these high molecular weight polymers has been the key issue for years – and an important challenge for us to help our customers. For those who have long mastered to utilise the most sophisticated high molecular weight polymers, the new materials may provide an opportunity to gain productivity. Now we can offer our customers a promising solution utilising new Lanxess rubber modification technology.“
In technical terms, this modification technology of the new Nd-PBR grades Buna Nd 22 EZ and Buna Nd 24 EZ is designed to create long chain branching, which accelerates the fast and reliable incorporation of fillers into the rubber matrix and improves processing. In addition, a proprietary chemical modification of the chains enhances the rubber/filler interaction, especially with carbon black in sidewall compounds maintaining the dynamic performance of the tyres made with the new grades at the high level of Lanxess standard Nd-PBR grades. Nd-PBR is rarely used on its own but in blends with other polymers particularly solution SBR in tyre tread formulations using silica as the filler. It has been shown that the modification also enhances the inter polymer phase distribution. This will lead to improved distribution of the filler in the resultant compound. In addition, the Lanxess rubber experts have achieved a significant increase in the rubber’s tackiness on the mill – without adding any processing aids.
“Summing up, these new modified Nd-PBR grades Buna Nd 22 EZ and Buna Nd 24 EZ represent attractive alternatives for high performance rubbers such as Nd-PBR Buna CB22 and Buna CB24. They show similar properties but are characterised by considerably easier processing characteristics,“ states Kim. Buna Nd 22 EZ, for example, can be processed in the same way as Buna CB24, but matches the dynamic performance of the high-Mooney grade Buna CB22, whose processing was much more demanding.
Buna Nd 24 EZ gives performance levels roughly equivalent to Buna CB24, but is as easy to process as a cobalt-polybutadiene rubber. “This enables tyre manufacturers to take their products’ performance to the next level,“ says Kim. “And we believe, this is still not the end of the flagpole: Lanxess is not just the world‘s largest rubber supplier relying purely on sophisticated R&D alone. We are also proactively listening to the rubber industry – as can be seen in the fact that we are testing our new tyre rubbers using very relevant conditions in dedicated tire testing laboratories resulting in the outstanding performance of our AA concept tyre we presented in September 2012. We are still on the road to develop even ‘greener‘ tyre rubbers and put them on the road even faster.“
Meanwhile, the chemicals speciality firm is currently constructing what it claims as the world’s largest NdPBR plant in Singapore. For it, Lanxess is investing an estimated EUR200 million in a 140,000 metric tonnes per annum facility on Jurong Island. The facility will be the largest of its kind globally and will serve the growing market for “Green Tyres”, especially in Asia; and about 100 jobs will be created, the firm says.