Rubber vulcanization accelerator M, the full name of rubber vulcanization accelerator 2-mercaptobenzothiazole, is a general-purpose accelerator, widely used in various rubbers, and has rapid vulcanization acceleration in natural rubber and general synthetic rubber. In addition, it also has certain plasticizing and anti-aging properties, and can be used as a retarder in chloroprene rubber. With the rapid development of my country's automobile and tire industries, the demand for rubber vulcanization accelerators and their derivatives has been stimulated and stimulated.
At the same time, the production process of rubber accelerator M at home and abroad will produce a considerable amount of "three wastes". It is no exaggeration to say that the environmental pollution problem in the production process of rubber accelerator M has become the main bottleneck restricting its development. Therefore, how to develop It has become a hot topic in the rubber additives industry to develop a relatively clean process technology, and at the same time strengthen the treatment and recycling of the "three wastes" generated in the current production process. Facing this new situation, the engineers of ZhangHua Machinery innovated and researched and developed the barrel-cone filter, washing and drying machine, which solved the worries of customers and made ZhangHua's contribution to the national environmental protection cause.
At present, domestic production enterprises mainly adopt the aniline method, which uses aniline as raw material to react with carbon disulfide and sulfur, which is divided into high-pressure method and normal-pressure method.
Because the high-pressure method can realize continuous production, and the cost is low, it is favored in the industry. In recent years, most of the domestic production has chosen the high-pressure method. The high-pressure aniline method is to synthesize the three raw materials of aniline, CS2 and sulfur under high temperature and high pressure, and then undergo a series of post-treatment separation and purification to obtain the rubber accelerator M. Its classic process is as follows:
(1) First, aniline and CS2 are dissolved at 220-280C and 8.0-10.0MPa to react to obtain the crude product M;
(2) Then through a series of separation processes such as alkali dissolution, oxidation, filtration, acidification, dehydration, and drying to obtain the fine product M;
(3) According to different post-treatments, it can be divided into acid-base method and solvent method.
The high-pressure aniline production process has stable conditions, low cost, and high product quality, but there are still high raw material consumption and high intermittent production costs. The whole reaction process is performed intermittently, and the degree of continuous mechanization is low. Finally, the accelerator M and the solvent are removed or extracted by a centrifuge, solid-liquid separation, and drying are completed in multiple independent equipment. The operation is cumbersome and labor-intensive. Large quantity, poor operating environment, unstable product quality and other disadvantages. Furthermore, the use of centrifuges in the presence of organic solvents increases safety risks.
At the same time, there is a lot of wastewater discharge, high electricity load, high-pressure synthetic waste gas H2S and excess CS2 are not recycled, and the discharged hydrogen sulfide is seriously polluted. Therefore, further improving the yield of products, reducing costs, saving energy and reducing emissions have become urgent problems to be solved.
The new refining process of rubber vulcanization accelerator M fully utilizes raw materials, has low cost, simple process, energy saving and environmental protection.
The process steps of the three-in-one multi-functional filter washing and drying equipment developed and produced by Wuxi ZhangHua Machinery are as follows:
(1) Add the crude rubber vulcanization accelerator M sodium salt solution into the reaction kettle, add water to control the sodium salt mass concentration at 55-65%, add dilute sulfuric acid dropwise, and neutralize the pH of the solution to 7-10;
(2) Add extractant to the solution obtained in the previous process, then feed pure oxygen, the reaction temperature is controlled at 40-50°C, and the extractant is a mixed solution of water, 27.5wt% hydrogen peroxide and 93wt% sulfuric acid;
(3) Add dilute sulfuric acid to the solution obtained in step (2), adjust the pH value to 5-9, and the stirring motor speed of the three-in-one reactor is 50-60r/min;
(4) Then use the three-in-one multi-functional filter washing and drying equipment to first settle, wash, and then filter, wash, and dry again. After the post-treatment process, the high-quality rubber vulcanization accelerator M is obtained.
The technical advantages of the three-in-one multi-functional filter washing and drying equipment produced by ZhangHua Machinery:
(1) The new refining method makes full use of raw materials, low cost, energy saving and environmental protection, simple and easy process, and convenient for large-scale industrial production;
Pure oxygen is passed into the crude M sodium salt, and pure oxygen can catalyze the intermediate product benzothiazole and anilinobenzothiazole in the crude M sodium salt to continue to react with sulfur to generate M, thereby increasing the M content in the crude M, the method The raw materials are fully utilized and the cost is saved.
(2) High-quality rubber promotes M, bright in color, 0.5-1.5% higher in purity than the prior art, 2-4% higher in yield, 1-1.5 h shorter in oxidation time, and 200-400 yuan/ton lower in cost.
The special three-in-one multi-functional filter washing and drying equipment for the production of rubber vulcanization accelerator M realizes the mechanization and automation of the production line of rubber vulcanization accelerators purified by solvent method, effectively solves solvent volatilization, reduces production energy consumption, has safe operating environment, low labor intensity, and low operating costs. low merit. Aiming at the problem that the acid-alkali purification process will generate a large amount of wastewater, the three-in-one multi-functional filter washing and drying equipment developed and produced by Wuxi ZhangHua Machinery Co., Ltd. can greatly reduce the amount of wastewater.