Forecast of Hot Spots in China's Rubber Raw Material Sector      

By Xu Chunhua, China Rubber Industry Association (CRIA)
With the emerging commitment to low-carbon economy around the world, green manufacturing has become one of the strategic guidelines for the sustainable development of the rubber industry in China. Developing rubber raw materials with safety, energy conservation and environmental protection is the basis of green manufacturing.

1. The development pace of new rubber sectors is accelerated

Natural rubber is the major raw material for the rubber industry. Due to restrictions from natural conditions, however, more than 70% of the demand for natural rubber in China has to be satisfied by imports.
   Eucommia rubber is the only natural rubber resource with development prospects in the world today except Hevea natural rubber. Eucommia ulmoides planting area is around 350 000 hectares in China today, accounting for 99% of the world total. According to estimates, areas suitable for the planting of Eucommia ulmoides exceed 10 million hectares in China. Rubber composites using Eucommia rubber have excellent abrasion resistance, wet skid resistance, shock absorption and rolling resistance reduction. Eucommia rubber can be said to be an important material used as supplement to natural rubber. Through research and development for several dozen years, the Eucommia rubber extraction technology has made major advances. China will promote planting, extraction and comprehensive utilization in the Eucommia rubber industrial chain.
   Due to special features of Eucommia rubber, the development of trans 1,4 polyisoprene (TPI), which is called synthetic Eucommia rubber, has also made great strides. It is estimated that using 1 ton of TPI in making tires can reduce gasoline consumption by 10 liters and cut carbon dioxide emission by around 20 tons. TPI can bring about remarkable effects in minimizing rolling resistance and reducing carbon dioxide emission. The 30 000 t/a TPI production unit developed by the National Tie Process Control Engineering and Technology Center will start production at the Dipai New Material Industry Base in Laizhou of Shandong province, eastern China, aiming to supply a new synthetic rubber variety for green tire manufacturing in China.
   The ideal rubber stock for tires should have the integration of high abrasion resistance, low rolling resistance and wet skid resistance. The three factors are however somewhat contradictory to each other and it is hard to have them all for a single rubber. Nevertheless, the styrene, isoprene and butadiene rubber (SIBR) is regarded as the optimal solution to this problem today. SIBR developed by Sinopec Beijing Yanshan Petrochemical Company has already passed the assessment conducted by the Material Research and Testing Center of CRIA and experienced trial production of sedan radial tires in Qingdao Sailun Co Ltd. It is proved that process features of SIBR can meet processing requirements. The successful R&D and commercialization of SIBR will make great contributions to energy conservation, emission reduction and green development of the rubber processing industry in China.
   The manufacture of rubber-carbon black masterbatch stock through the liquid-phase continuous process can greatly shorten mixing time, cut equipment occupancy and reduce heat buildup. The hysteresis loss of stock is also much lower, the abrasion resistance is improved, the energy consumption is greatly reduced and pollution is much lower. It has therefore won warm applause from rubber processing enterprises.
   Polyurethane used to manufacture tires has extremely good abrasion resistance and puncture resistance. Due to its defects such as heat buildup, poor adhesion with rubber and poor wet skid resistance of stock, however, its application in tires has always been restricted. Guangzhou Bestry Technology Co Ltd has made breakthroughs in these key technologies in recent years and constructed a 100 000 pieces/year tire production line with polyurethane as tread stock. The company is also putting up a 400 000 pieces/year tire production line with polyurethane as tread stock today.

2. The green production of the rubber assistant industry makes steady steps ahead

Clean production technology is still a key to the development of the rubber assistant industry around the world. China's production technologies for RT-Base (4-PADPA) and antioxidant 4020 are already world leaders. The fully-closed process route for the production of silane coupling agents and the technology for the production of cobalt salt bonding promoters developed by China itself also hold a leading position in the world.
   Some Chinese enterprises have already submitted applications to the state for projects to develop clean production technologies for accelerator M. They expect to achieve clean production within 2-3 years, and complete a 50 000 t/a demonstration production line and promised to conduct dissemination in the entire sector.
   In traditional processes for sulfonamide accelerators, great quantities of salt-containing organic waste water are easily generated. For example, producing 1 ton of accelerator NS generates 8-10 tons of salt-containing organic waste water. Renovating the oxidization process and using oxygen or hydrogen peroxide to conduct the oxidization reaction can prevent the generation of salt-containing organic waste water, and the consumption of water in the whole production process can also be greatly reduced.
   In the development program for the period from 2006 to 2010, the Chinese government included the development of production technologies for insoluble sulfur with high heat stability and planned to fund the related development. Research organizations in China developed a single-step production process and constructed several production units with a capacity of 10 000 t/a. The successful development and dissemination of the process technology will put an end to the need to import great quantities of insoluble sulfur with high heat stability for radial tires in China.
   The technology of dispersing great quantities of powdery rubber assistants in small amounts of polymer carriers to make pre-dispersed masterbatch stock is a part of clean processes for the production of rubber assistants as final products and also for their application in downstream products. It is also a major renovation to the product type of rubber assistants. A 10 000 t/a unit using such technology has already been completed in China.
   Due to restricted zinc resources, price rises and EU environmental protection regulations, vulcanizing activators with little pollution and high activity to reduce the consumption of zinc oxide have become an important research issue. China has already developed high-tech products such as nanometer zinc oxide, nanometer inorganic filler zinc and organic zinc compounds. A solid step forward has therefore been made.

3. Equal emphasis is laid on the development of carbon black with low rolling resistance and silica white with high dispersion

The contribution made by tires to the rolling resistance of the entire vehicle can reach 20%-30%. In rubber stock for tires, in addition to raw rubber, the proportion of reinforcing materials such as carbon black and silica white can reach a maximum of around 30%. They have significant implications on the reduction of the rolling resistance.
   Carbon black with low rolling resistance can help to reduce the rolling resistance of tires by around 10% and lower the gasoline consumption by around 3%. Chinese companies have already developed DZ series and HM1107 carbon black varieties with low hysteresis qu