China eyes new grip on EV sector with high-performance rare-earth rubber

China’s high-performance rare-earth rubber faces a commercial test as manufacturers seek to expand its use in electric vehicle (EV) and heavy-duty tyres, with market data suggesting it commands a higher price than conventional synthetic rubber.

Rare-earth cis-butadiene rubber grade ND9106 was quoted at 22,500 yuan (US$3,400) per tonne in China during the week from October 26 to November 1, compared with 16,660 yuan per tonne for conventional BR9000 in Shandong province, according to market data published by the China Rubber Industry Association on November 2.

For tyre manufacturers, rare-earth rubber offers better wear resistance, greater strength and lower rolling resistance. The expansion of domestic production could help make the material more widely available.

A 100,000-tonne-a-year production facility at Dushanzi Petrochemical Company in Karamay, Xinjiang Uygur autonomous region, completed a successful trial run on June 27, producing premium-grade rare-earth cis-butadiene rubber, according to an announcement by the Chinese Academy of Sciences’ Changchun Institute of Applied Chemistry on July 16.

The institute supported the technology’s industrialisation, describing the achievement as a “major breakthrough” in China’s proprietary rare-earth catalytic rubber technology and saying its core technologies were “fully under domestic control”.

The project would help meet “urgent demand for high-end grades” of rare-earth cis-butadiene rubber, support the development of China’s petrochemical new-materials industry and help “safeguard supply-chain security”, the announcement said.

The material is particularly relevant to EV tyres, as electric cars tend to be heavier than comparable petrol-powered vehicles and deliver high torque during acceleration, placing greater demands on tyre durability.

Low rolling resistance reduces the energy lost as tyres deform and roll along the road, while wear and fatigue resistance can extend tyre life under repeated mechanical stress.

Heavy-duty vehicles also benefit from rubber that can withstand high loads, repeated deformation and heat build-up. Greater resistance to tearing and fatigue can help improve tyre durability under demanding operating conditions.

The same combination of strength, wear resistance and durability could also be relevant to military tyres and other high-performance rubber components, although the institute has not disclosed details about supplying the material for weapons or military vehicles.

Compared with conventional nickel-based butadiene rubber, the rare-earth version offers greater wear resistance and strength, better resistance to fatigue and tearing, improved low-temperature performance, less heat build-up and lower rolling resistance, according to the institute.

The technology enables domestic production of BR1240 and BR1260, two national-standard grades of rare-earth cis-butadiene rubber that differ in Mooney viscosity, a standard measure of rubber viscosity and processability.

The rubber is made by polymerising butadiene using a rare-earth catalyst, which helps control the polymer’s molecular structure and, in turn, its mechanical properties.

The project translates decades of laboratory research into a reliable industrial process.

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A second-generation production technology developed by a team led by researcher Bi Jifu incorporates automated operations and domestically developed technology and equipment.

The team addressed several technical challenges, including precise control of catalyst structure, catalyst preparation, tolerance of different feedstocks and the integration of long-chain branching and functionalisation.

The South China Morning Post has contacted Bi’s team for comment.

The industrial breakthrough builds on more than six decades of research at the institute.

Its work on rare-earth-catalysed rubber dates to 1964, when scientists Ouyang Jun and Shen Zhiquan published a paper on the catalytic activity of rare-earth compounds in stereospecific polymerisation. The institute described it as the first international publication on using rare-earth catalysts to produce butadiene rubber.

In 1982, the institute’s work on stereospecific polymerisation catalysed by rare-earth complexes won second prize in China’s National Natural Science Award, laying the foundation for further research and industrial applications.

Researchers including Bi, Jiang Liansheng and Zhang Xuequan subsequently conducted thousands of scale-up experiments and dozens of pilot trials to develop an industrial process package based on domestically developed technology.

The institute said its work had progressed “from addressing urgent needs of the national economy” to “supporting the modernisation of national defence”.

Its earlier defence-related work included developing liquid polysulphide rubber used as a binder for composite solid propellants, a material that supported China’s “two bombs, one satellite” programme.