Factors Affecting The Mixing Of Internal Mixer
2023-03-16
Compared with open mixer mixing, internal mixer mixing has the advantages of short mixing time, high efficiency, high level of mechanization and automation, good rubber quality, low labor intensity, safe operation, small dust loss, and good environmental sanitation conditions, etc. Advantages, but the heat dissipation in the mixing chamber of the Internal Mixer is difficult, the mixing temperature is high and difficult to control, so that the temperature-sensitive rubber is limited, and it is not suitable for the mixing of light-colored rubber and frequently-changing types of rubber. In addition, the internal mixer needs to be equipped with the corresponding lower piece installation.
1. Glue quantity A reasonable amount of glue should be able to ensure that the rubber is subject to maximum friction and shearing in the mixing chamber, so that the compounding agent is evenly dispersed. The amount of glue loaded depends on the characteristics of the equipment and the characteristics of the glue. Generally, it is calculated based on the total volume of the mixing chamber and the filling factor, and the filling factor is 0.55~0.75. If the equipment has been used for a long time, due to the wear and tear of the mixing room, the filling factor can be taken as a large value, and the amount of glue can be increased. If the pressure of the upper bolt is relatively high, or the plasticity of the rubber material is relatively large, the amount of glue installed can also be increased accordingly. 2. Upper bolt pressure Increasing the pressure of the upper jacking bolt can not only increase the rubber loading capacity, but also make the contact and extrusion between the rubber material and the equipment and the parts inside the rubber material faster and more effective, and accelerate the process of mixing the compounding agent into the rubber, thereby Shorten the mixing time, improve production efficiency, and at the same time reduce the sliding of materials on the contact surface of the equipment, increase the shear stress on the rubber, improve the dispersion level of the compounding agent, and improve the quality of the rubber. Therefore, at present, measures to increase the diameter of the upper bolt air cylinder or increase the wind pressure are often taken to improve the mixing efficiency of the internal mixer and the quality of the rubber compound. 3. Rotor speed and rotor structure shape During the mixing process, the shear rate of the rubber material is proportional to the rotor speed. Improving the shear speed of the rubber material can shorten the mixing time, which is an important measure to improve the efficiency of the internal mixer. At present, the speed of the internal mixer has been increased from 20r/min to 40r/min, 60r/min, and up to 80r/min, which shortens the refining cycle from 12~15min to the shortest l~l.5min. In recent years, in order to meet the requirements of the mixing process, a multi-speed or variable-speed internal mixer has been used for mixing. The speed can be changed at any time according to the characteristics of the rubber material and the process requirements to obtain the best mixing effect. The structural shape of the rotor of the internal mixer has a serious impact on the mixing process. The ridges of the elliptical rotor of the internal mixer have been increased from two to four, which can play a more effective role in shearing and mixing. It can increase production efficiency by 25-30% and reduce energy consumption. In recent years, in addition to oval, internal mixers with triangular, cylindrical and other rotor shapes have been used in production. 4. Mixing temperature During the mixing process of the internal mixer, the heat generated is large and the heat dissipation is difficult, so the temperature of the rubber material rises quickly and the temperature is high. Generally, the refining temperature is 100-130 degrees, and 170-190 degrees are also used for high-temperature refining. This process has been used in the mixing of synthetic rubber. The debinding temperature is generally controlled at 125-125 degrees during slow-speed mixing. 135 degrees, and the deglue temperature reaches above 160 degrees during rapid banburying. Excessive mixing and high temperature will reduce the mechanical shearing effect on the rubber, make the mixing uneven, and intensify the thermo-oxidative cracking of rubber molecules, reduce the physical and mechanical properties of the rubber, and at the same time, promote the rubber and Excessive chemical separation between carbon blacks will generate too much gel, which will reduce the plasticity of the rubber material, and the surface of the rubber material will be rough, resulting in difficulties in calendering and extrusion processing. 5. Precedence of adding medicine Plastic rubber and masterbatch should be added first to form a whole, and then other compounding agents should be added in sequence. Solid softeners and small medicines are added before adding fillers such as carbon black to ensure sufficient mixing time. The liquid softener must be added after adding carbon black to avoid agglomeration of carbon black and make it difficult to disperse; super-accelerator and sulfur are added after the tablet machine cools down, or in the internal mixer during the second-stage mixing, but other The degumming temperature should be controlled below 100 degrees. 6. Mixing time The mixing time depends on various factors such as the performance characteristics of the internal mixer, the amount of glue loaded, and the formula of the glue. Mixing and increasing the time can improve the dispersion of the compounding agent, but if the time is too long, it will easily form over-mixing, and it will also affect the vulcanization characteristics of the rubber compound. At present, the mixing time of XM-250/20 internal mixer is 10~12min.We have Rubber Internal Mixer on sale, if you are interested, you can consult us.
