Hot/cold mixing unit for PVC

日期:2019/6/6 8:44:19 / 阅读: / 来源:本站

Hot/cold mixing unit for PVC
(1) Mixing with a hot mixer. Any PVC product formulation consists of several or even dozens of different raw materials. All kinds of raw materials, including PVC resin, stabilizer, impact enhancer, processing aid, lubricant and colorant, must be mixed. Evenly. This requires a mixing process that is compatible with it. The quality of the material mix directly affects the quality of the product, which is a key process in PVC processing.
The hot mixer is a closed vertical equipment, which has the characteristics of high speed, high efficiency and uniform mixture. It is composed of mixing chamber, liquid automatic heating spray device, paddle, baffle, discharge port, machine base and transmission. The composition of the device, the volume of 300L resin and the auxiliary agent enters the mixing chamber from the upper part, and the industrial leaves at the bottom of the mixing chamber are stirred and mixed at a speed of 400/800min, and the material is centrifugally driven.
The effect rises along the wall of the mixing chamber, and falls into the center of the mixing chamber after hitting the baffle, so that the stirring is repeated repeatedly to quickly disperse the components. The heat is generated by friction between the material and the material, and between the material and the chamber wall, so that the material quickly reaches the mixing end temperature. The main points of the hot mixing process are as follows.
1 metering. The components were accurately weighed according to the ratio of the formulation.
2 feeding sequence. After the sieved PVC resin is placed in the mixing chamber, the stabilizer is first mixed with it, followed by the impact enhancer, processing aid, lubricant and colorant. If a liquid stabilizer is added, it should be preheated to about 50 °C, and then slowly added. If the hot mixer is equipped with a liquid spray device, it is mixed and sprayed, and the effect is better. Must pay attention: colorants
Improperly applied, it will cause agglomeration in the material, affecting the dispersion; the addition time of the impact enhancer should be added after the liquid stabilizer PVC resin is first mixed, such as MBS and liquid additives, MBS will first absorb the liquid auxiliary. This will increase the difficulty of mixing MBS and PVC and affect the uniform dispersion of MBS in PVC.
3 mixing temperature and time. The material is thoroughly mixed, stirred and sheared in a high-speed mixer. After reaching the end temperature of 110 °C-115 °C in 7 min-8 min, it is stirred and cooled in a cold mixing machine, and can be fed into the extruder hopper at 40 °C. It should be noted that the hot mixing temperature must be strictly controlled, the highest end temperature should not exceed 120 ° C, the summer room temperature is high, should also be appropriately reduced, otherwise the material
Decomposes overheating and a coking accident occurs.

作者:admin


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