Zhang Liqun, BUCT’s dean of material science and engineering, speaks at at the China Rubber Conference.

China's synthetic rubber imports are declining, but it should come as no surprise. 

The trend is beginning just as the country is stepping up its research and development efforts within the synthetic rubber sector, and working to establish itself as a leader in technology and materials. These combined efforts have led to increased production and, ultimately, larger export volumes.

It's a shift that seems to indicate a turning point for the domestic rubber industry, according to the China Rubber Industry Association.

China's synthetic rubber imports fell by 10.4 percent to 1.2 million metric tons in 2018, while exports rose by 9 percent to 153,000 tons, marking the reversal of a trend that had been building for several years.

China, last year, also stepped up its synthetic rubber production, increasing it by about 3 percent to 3.7 million tons, compared to 2017. Consumption throughout the country reached 4.9 million tons last year.

Averaging a 65 percent capacity-utilization rate in 2018, domestic suppliers now are able to meet the country's demand in all major synthetic rubber types, CRIA said. 

Among the imports, ethylene-propylene rubber, styrene-butadiene rubber, butadiene rubber and halobutyl rubber are the most popular, but ethylene-propylene rubber is the only elastomer type that showed import growth.

Technology is playing a key role in allowing China to increase synthetic rubber production. One of the projects involves construction of a smart plant that, by 2020, could reduce operational costs production cycle times and scrap rates by a third.

In March, Dawn Polymer started up its new HBNR facility in Yantai, China. The plant, which represents a $15.6 million investment, has a capacity of 3,000 tons per year, and makes use of technology developed by Beijing University of Chemical Technology.

BUCT is among China's leading developers of synthetic rubber new materials. It began working with Dawn in 2003, when a joint elastomer manufacturing site was established. This collaboration also fueled new applications at some of China's top tire makers.

For instance, nano clay-rubber, which was jointly developed with China's natural rubber major Hainan Rubber, has been used by Zhongce, Linglong and Aeolus since 2017. The material is said to have high cut- and wear-resistance, making it a good fit for aircraft or heavy-duty tires.

"It can increase tire life by at least 20 percent," Zhang Liqun, BUCT's dean of material science and engineering, said during his speech at the China Rubber Conference held in Guangzhou in March.

Able to achieve high dispersion at 60phr-or-above filling, BUCT's nano-silica rubber also is being used at Linglong and Aeolus. Goodyear has retrieved samples for testing as well, Zhang said.

In the area of chemically modified materials, Hainan Rubber has started mass producing epoxidized rubber. It has lower VOC emissions in the production process, and demonstrates good performance in stretch-induced crystallization and silica dispersion, according to Zhang. 

Epoxidized rubber, Zhang said, has been used in tire tread as "more epoxy groups mean better wet-skid resistance."

Bio-based elastomers, such as itaconate rubber, which are also changing the synthetic rubber landscape, Zhang said. Itaconate rubber can replace SBR or even acrylic rubber.

The first tire made from itaconate rubber already has been launched, according to experts at the China Rubber Conference. Further details about that development were not released.

Zhangdian Oriental Chemical plans to establish a pilot line for the material in Zibo, China, within the next few years. It is expected to have a capacity of about 1,000 tons per year.

In 2013, BUCT set up the world's first fully bio-based polyester elastomer unit capable of producing 100 tons of product each year. It is seeking a corporate partner to build a larger line with 1,000-ton annual capacity.

One of the biggest environmental challenges facing tire tread materials involves fine wear particles. According to Zhang, "such particles produced from tires in China each year can cover the area of France."

BUCT is looking at how to address this issue. It has partnered with the French Academy of Sciences and Chinese new materials firm Red Avenue to conduct further research on controlled degradation—good wear resistance without pollution. Red Avenue expects to open pilot line with 1,000 tons of annual capacity in Shanghai within the next two years.

Throughout China, thermoplastic vulcanizates are gaining popularity as a recyclable material. Dawn has completed China's first 10,000 tons-per-year facility for bromobutyl rubber/polypropyleneTPV. Its products are FDA-approved for use in medical rubber plugs. 

China's medical plug sector has a 1 billion unit annual capacity and consumes 15,000 tons of halobutyl rubber each year. 

"The new application is quite (promising)," Zhang said.

Dawn, BUCT and Zhongce also joined forces in November in the application of BIIR/PA TPV on automotive and bicycle inner tubes as air impervious liner. In the form of a dynamically vulcanized alloy, such material can raise airtight durability by 50 percent, compared with traditional materials, and reduce thickness from 1-1.5mm to 0.2-0.3mm. 

"The manufacturing process is revolutionized, too, as you no longer need a curing machine," Zhang said. "We'll likely finish the project in two months time." 

Measures to enhance the use of "greener" material are being taken on a national level as well. 

China, for instance, aims to plant 7.2 million square feet of dandelions for rubber extraction in border provinces Heilongjiang, Inner Mongolia and Xinjiang. So far, 2.2 million square feet of dandelions have been planted. Linglong, in 2017, invested $450 million to build a farm of its own.

For gutta percha, China hopes to shape it into a scaled industry within 10 years. The country already is commercializing gutta percha aircraft tires, which are said to have passed 397km/h high-speed dynamic simulation tests. 

Scrap rubber recycling also is attracting attention, including facilities for continuous vulcanization of scrap rubber using multi-stage screw extruders—technology developed by BUCT and commercialized by Nanjing, China-based Green Gold Giant Rubber & Plastic.

Units have been sold to six Chinese companies, among them Zhongce and state-owned scrap rubber processor BESG Xingyu, as well as Slovakia's Resumo. Each facility has 5,000 tons of annual capacity.

Still, Zhang believes research on synthetic rubber is less than satisfactory in China, citing the highly dispersed nature of the industry as one significant reason: "How can you ask a small company to spend more on research when it only has ($1.4 million in) annual profit?"

Furthermore, he urged synthetic rubber makers to reach out more to downstream firms and develop products based on their actual needs with computational materials design technology. 

Zhang listed a number of emerging areas for applications such as robotics, health care, smart transport and disaster prevention, where rubber already is used to make products such as synthetic muscle or skin and earthquake bearings.

"I see a lot of future growth points in those areas," he said. "We are entering a new age of materials genome."