By Xiao Ming
Isobutylene-isoprene rubber (IIR) could be mainly divided into ordinary IIR and halogenated isobutylene-isoprene rubber (HIIR). While having general features of ordinary IIR, HIIR – mainly produced by solution continuum method – is superior in reactivity, curing speed, heat resistance, etc. Hence rapid development in recent years and a good choice for producing tubeless tires’ sealing layer, radial tires and medical bottle stoppers. At present, most ordinary IIR producers adopt slurry process.
Production
There were five domestic IIR producers at the end of December 2021, boasting a combined capacity of 505 000 t/a and mainly distributed in North China, East China and Northeast China. More specifically, Sinopec Yanshan Petrochemical Company (Sinopec Yanshan) introduced technology from Italian PI in 1999 to construct a 30 000 t/a ordinary IIR unit, and the company’s IIR capacity rose to 135 000 t/a in 2021. Currently it is the largest IIR producer in China. Zhejiang Cenway New Materials Co., Ltd. (Zhejiang Cenway) constructed a 50 000 t/a IIR unit in 2010, utilizing domestic technology and expanding capacity to 100 000 t/a in 2021. The company, producing both ordinary IIR and HIIR, currently is a major IIR supplier in China.
In 2013, Liaoning Panjin Heyun New Materials Co., Ltd. introduced the slurry process from Russia and constructed a 60 000 t/a IIR unit, which has halted production since 2016. In 2020, Zhejiang Cenway subsidiary Panjin Cenway New Materials Co., Ltd. restarted the unit and expanded its capacity to 100 000 t/a. In 2015, Formosa Ningbo Co., Ltd. constructed a 50 000 t/a IIR unit, mainly producing ordinary IIR (A351) and currently not running. Shandong Chambroad Sinopoly New Material Co., Ltd. (Shandong Chambroad) constructed a 50 000 t/a IIR unit in 2015, and a 70 000 t/a brominated IIR unit in 2021, when the company’s IIR capacity rose to 120 000 t/a.
Domestic output of IIR has increased in recent years, reaching 138 000 tons in 2017. In 2021, the output was up 34.25% YoY to 294 000 tons, with ordinary IIR output accounting for 23.6% and HIIR output taking up 76.4%. Production of ordinary IIR and HIIR for 2021 grew 117.2% YoY and 37.6% YoY, respectively.
Import
Import volume of IIR saw ups and downs from 2017 to 2021, hitting the lowest of 217 700 tons in 2021, down 23.35% from the highest in 2020 (see Figure 1 for details), according to customs statistics. Import volume of HIIR showed a downward trend because of China’s increasing HIIR output. China imported IIR mainly from Russia, Saudi Arabia and Singapore during 2017-2021, with volume from the three making up 63.34% of the total and reaching 137 900 tons, both in 2021. Table 1 shows main HIIR import sources from 2017 to 2021.
Figure 1 China’s IIR import from 2017 to 2021
Export
Export volume of IIR fell and then increased during 2017-2021. In detail, China exported 16 640.25 tons of IIR in 2017, including 11 018.23 tons of ordinary IIR (66.21% of the total) and 5 622.02 tons of HIIR (33.79%). IIR export volume was up 96.4% YoY to 37 690.11 tons in 2021, when export volume of ordinary IIR reached 14 653.3 tons, occupying 38.88% of the total and soaring 91.33% YoY (HIIR export, 23 036.81 tons, 61.12% of the total, up 99.77% YoY).
In 2021, China exported 28 230.68 tons of IIR – taking up 74.9% of the total and up 173.71% YoY – to Hong Kong of China (2 550.14 tons, 6.77% of the total, up 757.59% YoY), Thailand (8 293.89 tons, 22.01% of the total, up 155.62% YoY), Pakistan (4 532.41 tons, 12.03% of the total, up 42.93% YoY), Vietnam (3 788.06 tons, 10.05% of the total, up 153.65% YoY), Indonesia (3 426.91 tons, 9.09% of the total, up 406.39% YoY), South Korea (3 175.78 tons, 8.43% of the total, up 268.15% YoY) and Canada (2 463.49 tons, 6.54% of the total, up 333.36% YoY). IIR exported via general trade totaled 32 396.51 tons in 2021, making up 85.95% of the total and up 109.91% YoY.
Consumption
Domestic apparent consumption of IIR fluctuated from 2017 to 2021, down 2.03% YoY to 474 000 tons in 2021, when IIR self-sufficiency rate was 62.03% (see Figure 2 for details). More specifically, ordinary IIR consumption reached 138 800 tons, and HIIR consumption totaled 335 200 tons. Further, ordinary IIR’s self-sufficiency rate was 50.07% in 2021, lower than 67% of HIIR’s. Around 85% of IIR was absorbed by tire firms, 10% by producers of medical bottle stoppers and 5% by other industries. Spurred by auto and pharmaceutical industries, urbanization and other factors, domestic demand for IIR is forecast to grow stably, and may reach 550 000 tons in 2026, including 440 000 tons of HIIR.
Figure 2 China’s IIR consumption and self-sufficiency rate during 2017-2021
Problems
At present, difficulties facing domestic IIR companies mainly involve backward state of technologies generally introduced from Italy or Russia, small capacity of production units, high production costs, product homogeneity, unstable product quality, lack of high-end products, etc. In addition, overcapacity may become a big problem in the next few years. Zhejiang Cenway plans to expand its IIR capacity to 150 000 t/a. Shandong Chambroad is constructing a 150 000 t/a unit, and phase I 70 000 t/a project has been put into production. If all new units come on stream as scheduled, domestic IIR capacity is forecast to reach 635 000 t/a in 2026, when demand may be only 550 000 tons, resulting in overcapacity and more intense competition.
Suggestions
Enterprises should greatly develop advanced, efficient and energy-saving technologies to produce HIIR, a main development direction but currently with a relatively low degree of self-sufficiency. Existing technologies and equipment should be upgraded to reduce environmental pollution, realize cleaner production and improve technical level of the whole IIR industry.
Low-level and redundant projects should be avoided, given that domestic IIR capacity may be excess in the next few years. Varieties of IIR products should be diversified, and serious product homogeneity should be solved, both by means of R&D of new products like star-branched butyl rubber; graphene, carbon nano tube and IIR/HIIR composites; etc. In addition, IIR firms are advised to strengthen cooperation with downstream companies, improve product quality, propel export trade, improve competitiveness in international markets, etc.
