Devolatilization
Devolatilization Line in Polymerization Post-process
The post-polymerization treatment devolatilization operation is another important application direction that reflects the special advantages of twin screw extruder.
Depending on the polymerization extrusion process, it is usually necessary to contain water, solvent, monomer, oligomer, reaction residual by-products and unstable end groups in various materials such as wet powder, glue, solution or melt after the reaction. The separation and recovery of the volatiles are sometimes accompanied by the addition of various additives and the refining and homogenization. This process is regarded as the post-polymerization treatment. Traditional or conventional equipment is often difficult to handle due to many complicated disadvantages such as high viscosity, phase change, and wall hanging. The special post-treatment twin screw machine can be used to achieve continuous and stable removal of various volatiles, greatly simplify the process, save energy, reduce costs, improve the operating environment and improve product quality. In most cases, it can be synchronized at one time. The extrusion granulation process is completed and the finished granules are directly obtained. A typical solvent evaporation type twin screw can handle a feedstock system having a solvent volatile content of up to 70-80%.
Typical Application
Chlorinated polypropylene de-70% carbon tetrachloride; PMMA de-monomer; K resin de- 50% cyclohexane; PPC polymer removal of 65% propylene oxide; PC copolymer devolatilization; PS copolymer devolatilization; The aryl ester is devolatilized; the polymer is detetrahydrofuran; the POM and fluoroplastic end groups are stabilized; and the excess portion is removed from the maleic anhydride graft system.
Flow chart of treatment of twin screw granulating unit after evaporation and devolatilization
1. Reaction kettle 2. Metering feed pump 3. Condensation tank 4. Multi-stage venting twin screw extruder 5. Second-stage twin screw extruder 6. Carrier injection 7. Water bath 8. Blower 9. Pelletizer 10. Finished product Silo 11. Weighing and bagging
Tandem Extruder
The first stage extruder is under normal pressure or slightly positive pressure for mixing extrusion, reactive extrusion or dissolution swelling extrusion. The second stage extruder is equipped with multiple vacuum venting chambers, to devolatilize solvents or volatiles in a low-speed, high-vacuum environment.
It is widely used in processing of aramid, and UHMWPE spinning etc.