Rubber accelerator MBT crude product refining, filtration, washing and drying machine

Rubber accelerator MBT is a general-purpose accelerator, widely used in various rubbers. In natural rubber and general synthetic rubber, it has a rapid vulcanization promoting effect. In addition, it also has certain plasticizing and anti-aging properties and can be used as a retarder in chloroprene rubber. Meanwhile, its derivatives such as CZ, NS, DZ, NOBS, etc. have better performance in promoting rubber vulcanization. Rubber accelerator MBT is easily dispersed in rubber and does not cause pollution. It is mainly used for manufacturing tires, inner tubes, rubber belts, rubber shoes and industrial products, etc.

At present, in industry, the high-pressure method is generally used to produce rubber accelerator MBT. That is, aniline, sulfur and carbon disulfide react at high temperature (250-300℃) and high pressure (8.0-11.0Mpa) to obtain crude MBT. The MBT content in crude products is generally between 85% and 88%, which contains a considerable amount of resin and intermediate products. The presence of impurities limits the application of MBT. Therefore, crude MBT must be purified before it can be used as a commercial product, and the purification of MBT is particularly important. At present, there are mainly two methods for refining MBT: acid-base method and solvent method.

(1) Acid-base method

In the traditional acid-base method, air or oxygen is used as the oxidant. Although high-quality MBT products can be obtained, a large amount of odorous gases are produced during the production process, which is not conducive to the on-site environment and the occupational health of workers. Hydrogen peroxide is directly used as the oxidant. Although it can solve the problem of unpleasant odors, due to the strong oxidation capacity of hydrogen peroxide, it is difficult to determine the reaction endpoint, and MBT is prone to form DM, which in turn affects the quality of commercial-grade MBT.

(2) Solvent method

The crude MBT is extracted by liquid-liquid or solid-liquid extraction using organic solvents (such as toluene, carbon disulfide, aniline, chlorobenzene, methanol, etc., or a combination of several). Although the crude MBT can be refined, the purity of the obtained MBT product is low and it cannot be directly used as commercial-grade MBT for rubber vulcanization. When the MBT products obtained are used as disulfenamide raw materials at the same time, it will affect the product indicators of downstream disulfenamide accelerators.

Process Analysis of Crude Rubber Accelerator MBT Refining, Filtration, Washing and Drying Machine

The process of refining, filtering, washing and drying crude rubber accelerator MBT is a method for refining rubber accelerator MBT. The crude rubber accelerator MBT is dissolved in an alkaline solution at 30 to 90℃, and a complex oxidant composed of hydrogen peroxide and hydrogen peroxide slow-release agent is added. The reaction is stirred for 1 to 3 hours, and then filtered to obtain a clear and transparent MBT salt solution. Add acid solution to the MBT salt solution to adjust the pH to 6-7, then dehydrate and dry to obtain the pure light yellow rubber accelerator MBT.

(1) Prepare the salt solution of the crude high-pressure product of rubber accelerator MBT

The high-pressure product of rubber accelerator MBT was dissolved in a 30% ammonia water solution at 70℃, and water was added to form a 7% MBT-NH4 solution.

(2) Prepare the compound oxidant

Take 27% hydrogen peroxide and inositol hexaphosphate to prepare a 2% hydrogen peroxide solution. Add organic phosphates to the hydrogen peroxide solution and dissolve them thoroughly to obtain a complex oxidant.

(3) Crude rinsing process of rubber accelerator MBT

The impurities in the MBT-NH4 solution were removed by using a composite oxidant. The composite oxidant prepared in step 2 was added to the MBT-NH4 solution obtained in step 1. After stirring and reacting for 1.5 hours, a clear and transparent MBT-NH4 salt solution was obtained through filtration.

(4) Filtration, washing and drying process of rubber accelerator MBT solution

Add 8% dilute sulfuric acid by mass fraction to the clear and transparent MBT-NH4 salt solution obtained in step 3, adjust the pH value of the solution to 6-7, and dehydrate and dry to obtain high-purity light yellow MBT with a purity greater than 98.2%.

(5) The composite oxidant in the new process will not oxidize the MBT salt solution. After a period of reaction, it will automatically reach the endpoint. Therefore, there is no need to determine the endpoint, nor is there any concern that MBT will be oxidized to DM and affect the quality of MBT.

The crude refining production of rubber accelerator MBT adopts a filtration, washing and drying machine. The process flow is simple, significantly reducing the labor intensity of workers. At the same time, it stabilizes the product quality, enhances the safety of the entire process flow, and significantly improves the purification efficiency. The quality of refined MBT is significantly enhanced, and the purity of the products is all above 98%, which is very suitable for industrial production.