In The Plastic Modification Of Twin-screw Extruder, What Is The Difference Between Premixingandcompounding?

one sentence summary

Before the high polymer mixing host (such as twin-screw extruder, continuous mixer, Buss kneader, three-screw extruder, etc.), the modified materials (base materials, auxiliary materials, additives) are first mixed in the pre-mixing machine. Mix the ingredients in the middle, and the base material is operated below the melting point of the base resin;

Mixing - refers to above the main material port of the mixing host (including above the side feeding port), through the weighing scale (including weight loss scale, weight gain scale, solid volume pump, etc.) in the small blanking well (or bucket) to achieve coordination. ) to implement mixing (refining) in the host. The latter apparently wetting, dispersing, extruding and pelletizing above the melting point of the substrate.

The metering is called the compounding process.

With the technicalization, intelligence and digitization of modification plants, almost all upstream modification lines are equipped with weight loss scales.

Its advantages are:

Labor-enclosed operation, improved workshop conditions, and easy-to-pass enterprise EIA;

High precision and stable quality of special materials or masterbatches.

weakness is:

The one-time investment is large, and it may even exceed the host of the twin-screw extruder;

In the case of excessive powder or stickiness, the small blanking well (or bucket) is easy to bridge;

The lack of pre-wetting sequence, the large length-diameter ratio of the master batch twin-screw, and the complicated and harsh screw arrangement and combination of the twin-screw extruder.

Principles for selecting a premix process.

Reduce the one-time investment, give full play to the initiative of excellent technical personnel, explore the temperament of the main modified products, and explore the way to expand production in the future;

In the production of high-filled polyolefin masterbatch, additives such as polyolefin (powder) material, mineral powder, coupling and other additives should be pre-mixed in the high-mixer;

According to Chen Xinhua's senior engineer's point of view (see the formula photo below), it is premixed in the premixer (wetting the pigment), and then enters the extruder main engine for mixing and granulation (dispersion). Due to the guaranteed wetting time and effect, the mechanical internal force will further strengthen the wetting and dispersion, and the resulting color masterbatch will meet the needs of customers.

In the production of SPVC cable materials, it is very important to pre-mix loose PVC powder, plasticizer and composite stabilizer in high and low mixing!

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