Polyvinyl Chloride English abbreviation pvc, can be made of ethylene, PVC Bags chlorine and catalyst by substitution reaction. PVC is widely used in all walks of life due to its fire and heat resistance. (Such as the famous Italian "Rody" jumping horse), curtains, rolling doors, PVC Bags auxiliary medical supplies, gloves, some food preservation paper, some fashion and so on.
Polyvinyl chloride is made from vinyl chloride monomer (VCM) polymerization. Because 57% of the mass of its molecules is chlorine. So it is less oil used in the same mass than other plastics, but because the relative density of the plastic is large and other energy is consumed in the process of chlorine production, Many applications have lost the advantage.
The use of more PVC production process is suspended polymerization production process. The pure water, liquefied VCM monomer and dispersant are added into the reaction kettle, then the initiator and other additives are added. After heating to a certain temperature, PVC Bags the VCM monomer undergoes free radical polymerization to produce PVC particles. The continuous agitation allows the particle size to be uniform and the resulting particles are suspended in water. There are suspension polymerization method, emulsion polymerization method and bulk polymerization method, mainly in suspension polymerization, accounting for about 80% of total PVC production. In addition, there are micro-suspension production PVC paste with resin, product performance and paste into the paste are good.
Suspension polymerization method to suspend the monomer droplets suspended in the water phase, the choice of oil-soluble initiator is dissolved in the monomer, PVC Bags the polymerization reaction in these droplets, the polymerization reaction in a timely manner by water absorption, in order to ensure These droplets are dispersed in the form of beads, need to add suspension stabilizers, such as gelatin, polyvinyl alcohol, methyl cellulose, hydroxyethyl cellulose and so on. The initiator uses organic peroxides and azo compounds such as diisopropyl peroxydicarbonate, dicyclohexyl peroxydicarbonate, diethylhexyl peroxydicarbonate and azobisisoheptanonitrile, PVC Bags even Nitrogen diisobutyronitrile and the like. The polymerization was carried out in a polymerization vessel equipped with a stirrer. After the polymerization, the material flows into the monomer recovery tank or stripper to recover the monomer. And then into the mixing kettle, washed and then centrifugal dehydration, drying that resin products. The vinyl chloride monomer should be removed from the resin as far as possible. For food packaging with PVC, free monomer content should be controlled at 1ppm or less. PVC Bags Polymerization to ensure that the required molecular weight and molecular weight distribution of the resin and to prevent burst polymerization, must control the polymerization process temperature and pressure. PVC Bags The particle size and particle size distribution of the resin are controlled by the stirring speed and the choice and dosage of the suspension stabilizer. The mass of the resin is characterized by particle size and particle size distribution, PVC Bags molecular weight and molecular weight distribution, apparent density, porosity, fisheye, PVC Bags thermal stability, color, impurity content and free flow of powder. Polymerization reactor is the main equipment, made of steel kettle body made of stainless steel or enamel, equipped with a stirrer and control the temperature of the heat transfer jacket, or internal cooling row, reflux condenser and so on. In order to reduce production costs, PVC Bags the reactor volume has been a few cubic meters, more than ten cubic meters to the large-scale development, the largest has reached 200m (see kettle reactor). Polymer can be used after repeated use. PVC made of polyvinyl alcohol and cellulose ethers as the suspension stabilizer is generally more loose, porous, surface area, easy to absorb plasticizer and plastic.