The automatic compounding system implements a process that we call the mixing process. This raises another question: What is the compounding process? In this article, we will briefly introduce it.
Here is the list of contents
What is compounding?
How to control the mixing time?
Blending is the process of homogenizing PVC resin with heat stabilizers, modifiers, lubricants, fillers, colorants, and other additives. The equipment used is mainly a high-speed kneader and cooling mixer. The process is not complicated, but the quality of mixing directly affects the normal production and quality of products. The process of mixing is to rely on mechanical force on the material generated by the friction between each other, shear force to refine the material, heating, so that some additives melt, covering the surface of PVC resin. PVC resin in the shear, friction refinement, the surface under the action of temperature is loose, porous, the additives adsorbed on the surface and reach uniformity, the temperature further increases, the surface of the particles melted, the density of particles The temperature further increases, the surface of the particles melts and the density of the particles increases.
High-speed mixer efficiency is higher, the time used is much shorter than the Z-type kneader, usually a mixing time of only 8 to 10 minutes, the material temperature rises quickly with the friction of stirring, in 8 to 10 minutes the temperature can rise to 120 ~ 140 ℃, generally by controlling the material temperature to control the mixing time, temperature control at 125 ~ 135 ℃ discharge, the material quickly into the cooling mixer. After the material is into the cold mixer, in the slow rotation of the stirring paddle, can be radial and part of the axial mixing, so that the cold material is in contact with the cooling jacket and away from the cooling surface of the hot material mixed, effective heat exchange so that the temperature of the material to reduce. Material temperature down to 45 ℃ or less, can be discharged from the discharge port.
The volume of the cold mixer should generally be more than twice the volume of the high mixer. This can ensure the continuity of the mixing process, to help obtain a uniform dry mix. The dry mix preparation process should be strictly controlled by process parameters. Some manufacturers tend to pay attention only to the quality of raw materials, formulations, as well as the process of extrusion molding process control, and the preparation of the mixing process does not pay enough attention. The actual production of many product quality fluctuations, that is caused by the dry mix preparation process is not strictly controlled or unreasonable.
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