How polyvinyl chloride is made

How is polyvinyl chloride made? Explain the production process of polyvinyl chloride in detail

polyvinyl chloride (PVC) is a synthetic resin widely used in the fields of construction, electronics, medical and consumer goods. It has good chemical resistance, abrasion resistance and high strength, so it is widely used in the production of pipes, floors, window frames and other products. How is PVC made? We will analyze the production process of PVC in detail.

1. PVC Basic Raw Material-Vinyl Chloride Monomer

The main component of polyvinyl chloride is vinyl chloride monomer (VCM,Vinyl Chloride Monomer). This chemical is usually synthesized by chlorinating ethylene. Ethylene (C2H4) is a light hydrocarbon compound commonly found in natural gas or petroleum, while chlorine (Cl2) is obtained by electrolysis of seawater. The preparation of vinyl chloride involves the reaction of ethylene with chlorine to form vinyl chloride. In the production of vinyl chloride, the control of reaction conditions plays an important role in the purity and production efficiency of the final vinyl chloride.

2. Polymerization-Polyvinyl Chloride Synthesis

After vinyl chloride monomer is synthesized, it is converted into polyvinyl chloride through polymerization reaction. The polymerization process usually uses two common methods of free radical polymerization or suspension polymerization. Free radical polymerization methods are commonly used to produce higher molecular weight PVC, while suspension polymerization is suitable for the production of more detailed granular PVC. The specific polymerization reaction includes initiating a free radical reaction of vinyl chloride monomer at a certain temperature and pressure to promote the growth of vinyl chloride molecules, and finally form a long-chain polymer of polyvinyl chloride.

Suspension polymerization is the most common method in the production of polyvinyl chloride. It is carried out by dispersing vinyl chloride monomer in water and starting the polymerization reaction by adding a certain initiator (such as peroxide). Polyvinyl chloride particles generated in the polymerization process will be suspended in the water phase, and finally granular polyvinyl chloride products can be obtained through filtration, drying and other treatments.

3. PVC post-treatment-removal of impurities and adjustment performance

After the polymerization reaction is completed, the obtained polyvinyl chloride is not a final product that can be directly used, and some post-treatment steps are required. These steps include removing impurities such as unreacted vinyl chloride monomer, stabilizer, plasticizer, etc., and adjusting the physical properties of polyvinyl chloride.

The residual vinyl chloride monomer is removed by distillation and other technologies to ensure the purity of polyvinyl chloride products. Then, by adding different additives, such as heat stabilizers, anti-ultraviolet agents, plasticizers, etc., the processability and performance of polyvinyl chloride can be adjusted. For example, the addition of plastic plasticizers can improve the flexibility of polyvinyl chloride, making it suitable for different production applications.

4. PVC applications

PVC has excellent chemical stability, corrosion resistance and good processing performance, so it is widely used in many fields. For example, in the construction industry, PVC is used in the manufacture of pipes, window frames, cable sheaths, etc.; in the medical industry, it is used in the production of blood transfusion bags, pharmaceutical containers, catheters and other medical devices; and in the field of consumer goods, PVC is also commonly used in flooring materials, toys and daily household goods.

With the advancement of technology, the production process and product performance of PVC are continuously optimized, and its application will be further expanded to a wider range of fields such as environmental protection and automobiles in the future.

Conclusion

Through a detailed analysis of the problem of "how polyvinyl chloride is made", we can see that the production process of polyvinyl chloride involves multiple links, including the synthesis of vinyl chloride monomer, the implementation of polymerization reactions, and post-processing. And the deployment of additives. With its excellent performance, polyvinyl chloride has become an indispensable material in modern industry, and with the continuous development of technology, its application prospects will be more extensive.