Factors Influencing Mixing Effect of Internal Mixer
Time: 2019-01-22 09:43:18Copyfrom: Wuxi Tengyu Environmental Protection Technology Co
The type and number of edges of the rotor have high shearing speed, but the heating rate is high, the mixing time is shortened, and the mixing quality is affected. Affected by the type of rotor, the shear dispersion zone is between the rotor edge and the mixing chamber. It has a wide range of forces, large shear force, high efficiency and good mixing quality. The meshing type is that the dispersed zone is between the two rotors. The shear force is small, the heat generation is low, and the mixing time is long and the dispersing effect is good.
2. Top bolt pressure
The function of top bolt is to keep the rubber in the mixing working area of the mixing chamber. Insufficient pressure will cause the rubber to slide on the wall of the mixing chamber and the surface of the rotor. Appropriate pressure can reduce the void in the material and increase the contact force. Pressure will increase the temperature of the compound and the mixing power. The filling capacity is insufficient, the top bolt pressure can not fully play its role, and the rubber is unevenly dispersed.
Each rubber has its optimum mixing temperature range. The type and amount of raw rubber, reinforcing agent and softener determine the mixing temperature rise. At the same temperature, the longer the mixing time, the better the dispersion.
4. Filling capacity
It depends on the effective volume of the mixer itself. The type of raw rubber in formula, the dosage of reinforcing filler and plasticizer. If the plasticity of raw rubber is high, the loading quantity should be larger. The filling coefficient (weight) is between 0.65 and 0.75, and the necessary shear force can not be obtained when the filling quantity is insufficient.
5. The order and effect of feeding are different.
In the automatic system mixing, the basic choice (using multi-stage mixing, according to the requirements of the compound) is raw rubber-extractor-adding filler/compounding agent-pressing-extracting-adding softener-pressing-extracting-extracting and discharging.
The rotational speed is proportional to the shear rate, and the homogeneous mixing is accelerated when the shear rate is large. Increasing the rotational speed will increase the temperature of the rubber, resulting in the decrease of the viscosity and shear stress of the rubber.
The mixing time is related to the amount of filling and the temperature rise of formula. The mixing temperature affects the mixing time. The speed of mixer and the pressure of top plug also affect the mixing time. Therefore, the auxiliary time and feeding time can be shortened as far as possible in the mixing process.
8. Cooling water
Cooling water temperature is generally set at 15 degrees. Low viscosity rubber is not easy to be cooled by hot water. It is easy to stick the rotor. High viscosity rubber is cooled by hot water. Increasing cooling water temperature can shorten mixing time, reduce energy consumption and improve production efficiency.