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Summary: PVC (specific purposes at section fourth) PVC (Polyvinyl Chloride, referred to as PVC), is China's first, the world's second largest general-purpose synthetic resin material with flame retardant, wear resistance, chemical corrosion resistance, mechanical products, transparency, electrical insulation and easy processing etc. excellent characteristics, at present, PVC has become one of the most widely used plastic varieties, widely used in industry, construction, agriculture, daily life, packaging, electric power, public utilities and other fields, and polyethylene (PE), polypropylene (PP), polystyrene (PS) and ABS are collectively referred to as the five general resin.
Polyvinyl chloride PVC is a non-toxic, odorless white powder. It has high chemical stability and good plasticity. In addition to a small number of organic solvents, temperature resistant to any concentration of hydrochloric acid, 90% sulfuric acid, 50 ~ 20% and 60% of the nitrate salts for caustic soda, also quite stable; poor thermal stability and light resistance of PVC, at 140 DEG to start the decomposition and release of hydrogen chloride (HCl) gas, causing discoloration of PVC. PVC good electrical insulation, generally does not burn, the flame can burn and release HCl, but leave the flame that is self extinguishing, is a "self extinguishing", "refractory" material. Based on the above characteristics, PVC is mainly used in the production of profiles, profiles, pipe fittings, plates, sheets, cable sheath, hard or soft tube, blood transfusion equipment and film and other fields.
Two, according to the classification of polyvinyl chloride according to the scope of application, PVC can be divided into: General PVC resin, high degree of polymerization of PVC resin, crosslinked PVC resin. The general PVC resin by polymerization of vinyl chloride monomer is formed under the action of initiator; high degree of polymerization of PVC resin is resin in the polymerization of vinyl chloride monomer added to the system, the chain growth polymerization crosslinking agent; PVC resin is added to the resin crosslinking agent containing dienes and polyenes in vinyl chloride monomer polymerization polymerization system. The general type of PVC because of simple preparation method, wide use, circulation on the spot market in the most common type of PVC resin, PVC resin with high degree of polymerization and crosslinking in the special field of application of more general. According to the method to distinguish the vinyl chloride monomer, can be divided into electric stone, and imported ethylene (EDC, VCM) monomer method (on the habits of the ethylene monomer and import system called ethylene method).
At present, most of the world is ethylene PVC, while in China, the main method is PVC. According to the polymerization method of vinyl chloride monomer, polyvinyl chloride is obtained by suspension method, emulsion method, bulk method and solution method. Suspension method with its simple production process, easy to control and large-scale production, product suitability is strong, is the main mode of production of PVC, from around the world, the suspension of PVC production accounts for about 80% of the total. Without water and dispersant polymerization, polymerization of postprocessing is simple, the product purity is high, but there are problems in the polymerization process of mixing and heat transfer, the production cost is high, is out of class technology, the production capacity of less than 10% of the total, China currently only Sichuan Yibin days of the original production of PVC using ontology method.
Emulsion polymerization with water as the dispersion medium, made of fine particles, thermal stability and electrical insulation is poor, suitable for paste resin production, mainly used in the manufacture of artificial leather, impregnated gloves, screens, paddy field boots, tool handles, wallpaper, flooring material, battery separator and play out, I PVC paste resin in the production of less than 4% of the total output of PVC. Solution polymerization is only used in the production of coatings or specialty products. In the United States, the use of a variety of polymerization method of production of resin ratio is: suspension 87.8%, emulsion and micro suspension method 6.4%, bulk polymerization method, solution method, 1.4%.
In China, more than 90% of the PVC is produced by suspension method. The production process and cost analysis of 1 three, PVC production process of PVC production mainly has two kinds of preparation technology, is a calcium carbide, calcium carbide, coal is mainly the production of raw materials and raw salt; two is ethylene method, the main raw material is oil. The international market mainly in the production of PVC ethylene method, while the domestic are rich in coal, oil, gas resources limited, mainly by carbide method, as of December 2007, China's PVC by calcium carbide accounted for more than 70% of total capacity. It is worth noting that, in the preparation of calcium carbide PVC, salt electrolysis hydrogen chloride for the production of PVC, sodium remaining for the production of caustic soda, therefore, chlorine and alkali actually had a symbiotic relationship, important factors to consider is the balance of chlor alkali industry in the process of the development of the. 2 cost analysis from the perspective of production costs, the two processes in different economic development cycle, the cost difference. Usually, in the international macro economy rapid development stage, due to high oil prices and higher ethylene production cost advantages, cost of electric stone is obvious; but once the international economy into recession, oil prices will be low, carbide method because of high energy consumption, electricity and so on price support, the cost advantage disappears. Since 2003, international oil prices rose sharply, to increase ethylene PVC cost, and the carbide process is affected by this small, resulting in device of domestic production of PVC by calcium carbide method the construction of a new round of upsurge, the carbide PVC production capacity is expanding rapidly, formed a great challenge to the ethylene production of PVC by ethylene method, many enterprises in the loss of the edge.
However, with the continued decline in crude oil prices in May 2008, the cost advantage of the ethylene method is obvious, and the manufacturers of the method of calcium carbide operation, or even unsustainable. The cost of calcium carbide is mainly composed of the cost of calcium carbide and hydrogen chloride