At present, more PVC production processes are used in suspension polymerization production processes. The pure water, the liquefied VCM monomer and the dispersing agent are added to the reaction vessel, and then the initiator and other auxiliary agents are added. After the temperature is raised to a certain temperature, the VCM monomer undergoes radical polymerization to form PVC particles. Continued agitation results in uniform particle size and suspension of the resulting particles in water. Since the reaction is an exothermic reaction, an effective heat removal heat removal device must be provided: such as a jacketed cooling water or a top condenser. Moreover, because the density of PVC is greater than the density of VCM. As the PVC continues to form during the reaction, the volume of the liquid phase in the reactor will shrink continuously, and pure water must be continuously added to maintain proper pressure. At different polymerization temperatures, the degree of polymerization of VCM polymerized PVC is different. Controlling different polymerization temperatures can produce PVC resins of different grades (different grades with different degrees of polymerization).
The generated PVC slurry is removed from the residual VCM gas through a stripping tower (recycled by a recovery system and recycled with fresh VCM in a certain ratio), then subjected to centrifugal dehydration, dried in a drying bed, and sieved to be packaged into a product. Generally, the VCM content in the PVC powder after post-treatment is less than 1 PPM. The remaining polymerization processes, such as micro-suspension and emulsion polymerization processes, can produce PVC powder with a smaller particle size (10 microns, while the PVC powder produced by suspension polymerization generally has a particle size of 120-150 microns. Its properties and applications are slightly different) The PVC produced by the polymerization is unmodified PVC . Before making the final product, it is generally necessary to add various additives such as: heat stabilizer, ultraviolet stabilizer, lubricant, plasticizer, processing aid, impact modifier, thermal modifier, filler, and resistance. Burning agents, insecticides, foaming agents, smoke suppressants and various pigments.
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