Experience Summary of PVC Blending Process Impact

Experience Summary of PVC Blending Process Impact

Author: PVC Maniac-Song Xiufeng

Main manifestations:

1. Add different raw materials to formula and change path of materials in mixer to achieve effect of initial distribution. The speed of this process is not critical. The speed is slow and work is done for a long time, but generated heat energy is reduced.

2, shear dispersion, other raw materials that are easy to agglomerate, cut and collide with high-speed blades to achieve purpose of dispersion. For example, CFE that has not been used for a long time can be pulverized at a certain speed in a mixer, and ultra-fine calcium powder can be used at high speed to increase accumulation volume of calcium powder by several times.

3, collision friction dispersion. This process mainly applies to fats and oils. At high speed, materials collide and rub against each other, which disperses materials with poor viscosity and polarity. This is equivalent to what I understand as process of making soap. No matter how big block is, it cannot withstand friction. For example, 1 piece of PE wax with a melting point of 110 degrees is mixed with PVC + calcium powder at a high speed of 900 rpm. When temperature reaches 60 degrees Celsius, material is clearly active and hydrophobic.

The finer polyethylene wax, worse effect. If speed is reduced to 60 rpm, a stabilizer is added, mixer is heated to 90 degrees and mixed for 20 minutes, then material is basically not hydrophobic. That is, grease does not disperse at all and can be wrapped with calcium powder. In this experiment, I personally believe that lubrication does not necessarily require a high temperature to dissipate, and can be done in a short time if speed is high enough.

4. Collision absorption dispersion - calcium powder. The particles of PVC resin powder are larger than resin, and discharge of cut volume of precipitate is too large. In high-mixing mixer, relative air resistance is large, and relative velocity of resin in state of large particles must be much higher than that of calcium powder. It is beneficial to absorb calcium powder during high and low speed collisions. At same time, friction and collision between them produces a thermal effect. The higher speed of mixer in this process, more obvious it is. (temperature and absorption). The trajectory effect is also fairly obvious. For example: use 10kg of resin, 2kg of superfine calcium powder, mix in mixer at 900 speed, and calcium powder will basically disappear at 60 degrees. In same experiment, speed was reduced to about 400 and effectiveness of calcium powder was evident. Although time is used for a long time, energy consumption has not decreased. There is no effect either (it takes a long time to reach 60 degrees after slowing down). Example 2, I often change blade structure of high mixer penterprises, and structure of blade makes material path too smooth. When calcium powder path and resin path are in same direction, relative impact speed decreases. The mixing time is long and degree of mixing is clearly poor.

I love main reasons and features for adding keys to top. When calcium powder particles are small enough, larger collision force, more absorbed by resin, larger amount of calcium powder absorbed by resin, more obvious effect of dispersion on subsequent processing. Calcium powder can be regarded as a plasticizing dispersion accelerator for PVC. At same time, some calcium powder will penetrate into structure of molecular chain of resin. Improve physical properties of PVC. Above is initial link of distribution and dispersion.

The source of thermal energy is directly proportional to speed. proportional to time. Not proportional to power consumption.

So, there are two things I don't like: ① slow speed (the so-called can mix tons of monsters), ② mixing disc blades.

The disc type is designed to pressurize and mix raw materials, and process is easy to agglomerate. But it can be used. The so-called cold mixer is a large equipment. I really can't agree with big cold mixer mixing crushed materials, it should be possible, I feel it is used to mix resin powder, theory doesn't make sense.

Experience Summary of PVC Blending Process Impact

Recommended Reading: PVC/PVC Blending Technology Principle and Practical Operation

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