In some complex process requirements of mixing extrusion, due to the raw materials or additives on the initial state, processing temperature, shear rate, material pressure and other processing conditions are quite different, there are mutual constraints, and even contradictory technological requirements. However, the screw speed of a single twin-screw extruder is the same, the temperature region between adjacent cylinders affects each other, and the establishment of pressure, the input of energy can not be realized independently completely according to the technological requirements. Therefore, separate the links with great difference in process requirements and complete on two extruders respectively, so as to eliminate the interaction between the functional areas. According to the two twin-screw extruders in the upper and lower stages of the specific process, they can be arranged differently on many parameters, such as screw L/D, screw rotation speed, extrusion pressure, screw outer diameter size and so on, so as to complete a complex extrusion process.

Typical application:

1. Thermal sensitive materials (crosslinker, foaming agent, etc.) or materials with large processing temperature: up stage, high temperature high rotation speed, completes compounding; down stage, adding low temperature material/additives, finishes compounding at low rotation speed, low temperature.

2. Devolatilization exhaust material: Up stage extruder finishes compounding extrusion, reaction extrusion or dissolved swelling extrusion at atmospheric pressure or micro positive pressure; Down stage extruder equipped with several vacuum exhaust chamber finishes devolatilization treatment to solvent or volatile matter at low rotation speed, high vacuum condition.

3. Long glass fiber reinforced material: up stage compounds resin, additives and filler, etc uniformly at high rotation speed; down stage added glass fiber, and disperses glass fiber uniformly at low rotation speed, so as to longer retain the length of the glass fiber.

4. silicone adhesive, etc multi-component, difficult-to-disperse material: up stage extruder equipped with multiple powder and liquid addition area mainly completes the addition and preliminary mixing of multi-component raw materials. Down stage extruder equipped with strong compounding screw structure completes the deep dispersion and mixing of each group of raw material.

Case description: