Method for manufacturing general-purpose polyvinyl chloride (PVC) resin by suspension method
I. INTRODUCTION
Polyvinyl chloride (PVC) is a widely used plastic material with excellent physical and chemical properties, such as chemical resistance, good electrical insulation, high strength, etc. PVC can be used to produce a variety of products, such as pipelines, wires and cables, plates, profiles, and so on. In the field of raw materials for chemical production, suspension method is a commonly used method to produce PVC resin. In this paper, the manufacturing method of general-purpose PVC resin by suspension method will be introduced in detail.
II. Raw Materials and Formulation
1. Vinyl Chloride Monomer (VCM): VCM is the main raw material for the production of PVC, which is generally produced by the reaction of acetylene and hydrogen chloride.
2. initiator: the initiator is the substance that initiates the polymerization of VCM, usually using persulfate, redox initiator and so on.
3. dispersant: the role of the dispersant is to prevent agglomeration of PVC resin particles, commonly used dispersants are polyvinyl alcohol, methyl cellulose, etc..
4. Deionized water: used as a reaction medium, but also play a role in regulating the reaction temperature.
Three, manufacturing process
Suspension method of producing PVC resin process mainly includes the following steps:
1. polymerization reaction: VCM monomer, initiator, dispersant, deionized water and other raw materials into the polymerization kettle, at the appropriate temperature and pressure for polymerization reaction to generate PVC resin particles. The polymerization reaction generally adopts intermittent production mode.
2. Stripping: After the polymerization reaction, the reaction mixture is sent to the stripping tower, where the unreacted VCM monomer is removed from the PVC resin particles by steam.
3. Drying: PVC resin particles after vapor stripping contain a certain amount of moisture and need to be dried. Generally use fluidized bed dryer, with hot air to take away the moisture in the resin particles.
4. Screening: After drying, PVC resin particles need to be screened to separate particles of different sizes to obtain the required particle size distribution.
5. Packing: The sieved PVC resin granules are packed, usually in plastic bags or paper bags.
4. Precautions
1. Strictly control the temperature and pressure of polymerization reaction to ensure the quality and yield of the product.
2. The type and dosage of dispersant have important influence on the size and form of resin granules, which need to be adjusted according to the actual situation.
3. Appropriate temperature and air volume should be controlled during drying to avoid breakage and bonding of resin particles.
4. Clean and stable operation of the equipment should be maintained during the screening process to ensure the screening effect.
V. Conclusion
Suspension method is a commonly used method to produce general-purpose PVC resin, which has the advantages of stable product quality and low production cost. In the production process, it is necessary to strictly control each process parameter to ensure product quality and yield. At the same time, strengthening the maintenance and repair of the production equipment to improve the operating efficiency and service life of the equipment is also an important part of ensuring smooth production.
