◎ Yang Honghui
“China is a big rubber auxiliary producer. Rubber auxiliary products are fine chemicals. The production of most of the varieties, especially vulcanization accelerator, all involves flammable, explosive and toxic materials or solvents. At present, almost all the production of rubber auxiliaries adopts the traditional intermittent tank production process, which has safety and environmental protection hazards. The ‘3·21’ Xiangshui Explosion Accident has sounded the alarm for rubber auxiliary enterprises.” On March 26, at the parallel forum of innovative leading of “2019 China Rubber Conference” held by CRIA in Guangzhou, Wang Zhiqiang, general manager of Weilin New Materials Technology Co., Ltd., said that micro-chemical technology, as a new development direction in chemical engineering discipline, was an important method to realize green, safe and efficient chemical process, and in the past two years, it had made important breakthroughs in the industrialization of rubber auxiliary industry and should be vigorously promoted.
Wang Zhiqiang stated that the current bottlenecks restricting the technical development of rubber auxiliary industry were mainly as follows: first, the heat transfer efficiency of traditional tank reactor was such low that the production of many products could only be fed by dripping, resulting in long production cycle and low production efficiency of products; second, the tank reacting mode had poor mass transfer effect, low product yield and many by-products, whose “three wastes” were more difficult to handle; third, for the traditional intermittent process, the exhaust gas emission was discontinuous, resulting in unstable gaseous phase concentration, etc. and bringing great difficulties to VOCs control; fourth, the level of equipment automation control was low, the production safety factor was low, and there were batch differences in product quality, etc.
As far as the current situation is concerned, there are many shortcomings in the utilization of traditional production modes, which will result in unreasonable resource utilization, further increase material waste and pollute the environment. Therefore, the utilization of fine chemical control for chemical industry is very important. It can make up for the shortcomings of traditional industries, and protect the environment at the same time.
Micro-chemical technology was developed in the mid-1990s by the combination of microelectronics and chemical engineering. It is a high-tech that realizes green synthesis and separation through process enhancement. It mainly adopts new equipment such as microfluidic control equipment, micro-reaction equipment, micro-mixing equipment, micro-separation equipment, micro-heat-exchange equipment, etc., based on the features of micro-scale flow controllability and efficient hybrid delivery, to effectively improve the apparent rate of reaction and separation process, greatly reduce equipment size, and improve the safety of the process. It features small mixing scale, fast mixing rate, small equipment size, small occupied space, large specific surface area, high transfer coefficient, safe process, easy control, short residence time, high production efficiency, small amplification effect, small industrialization risk, etc., and is one of the research hotspots of many scientific research institutions and enterprises at home and abroad.
Wang Zhiqiang gave a detailed introduction to the applied research of micro-chemical technology of Weilin New Materials Co., Ltd. in the continuous production of rubber accelerators M, DM and TBzTD.
In the application of M production, firstly, it has achieved continuous production and improved production efficiency. In multi-tank tandem continuous production, the residence time in micro-mixer is only 2 seconds, and that in tandem reactor tank is 0.5 hour. Compared with the time of traditional process batch of 8-10 hours, the production efficiency is increased by about 20 times. Secondly, the product yield and purity are improved, the one-time yield is increased to 92%, and the initial melting point is increased to 176 °C. Thirdly, the closed continuous production has reduced VOCs emissions.
In the application of DM production, firstly, it has achieved continuous production and reduced VOCs emissions. Secondly, the production efficiency and reaction speed are improved, and reaction time is shortened. Thirdly, the yield is improved and the reaction process is strengthened. The product yield is increased from 95% to over 98%, reducing the production of by-products. Fourthly, the quality is improved, and the initial melting point of product is increased to 173 °C.
In the application of TBzTD production, firstly, it has achieved continuous production and reduced VOCs emissions. Secondly, the production efficiency and reaction speed are improved, and reaction time is shortened. Thirdly, the yield is improved and the reaction process is strengthened. The product yield is increased from 95% to over 99%, reducing the production of by-products and reducing wastewater treatment costs. Fourthly, the quality is improved, and the initial melting point of product is increased to 132 °C.
Finally, Wang Zhiqiang concluded that the micro-chemical technology had the following main advantages in the production of rubber auxiliary: first, it can achieve precise control of chemical production process, including production cycle, reaction temperature and material ratio, etc. It can reduce human operating error by automatically and continuously precise control. It has excellent mass transfer and heat transfer effects, which can improve the reaction selectivity and reduce the generation of by-products. It can also shorten reaction time and improve production efficiency. Second, it can achieve a more safe, reliable, green and environmentally friendly chemical production. Its closed and continuous production reduces the emission of VOCs; the liquid holdup is small, which is safer and controllable; the material consumption is reduced, the COD concentration in wastewater is reduced, and the biochemical treatment is easier.
Wang Zhiqiang remarked that the application of micro-chemical technology enabled the production of rubber auxiliary to be safe, efficient, fast and continuously controllable, and it was a high-tech very suitable for production conversion and comprehensive promotion. In the past two years, rubber auxiliary enterprises have done a lot of research and exploration in micro-chemical production. Last year, they made major breakthroughs in industrialization. The micro-reaction channel production lines have achieved industrialization for 10,000 tons/year anti-aging agent TMQ of Shandong Stair Chemical & Technology Co., Ltd., and 5,000 tons/year accelerator TBzTD of Weilin New Materials Technology Co., Ltd. At the same time, the micro-chemical reaction technology has laid a good foundation for the realization of intelligence after making the production of auxiliaries be continuous and automated. He believed that with the constant deepening of micro-chemical technology research and industrialization promotion, the rubber auxiliary industry would usher in a comprehensive upgrade of safety, environmental protection and intelligence, and the era of Industry 4.0 era was close at hand.
