General purpose polystyrene, is based on styrene as a monomer through free radical polymerization or ionic polymerization obtained. Production methods are bulk polymerization, solution polymerization, suspension polymerization and emulsion polymerization. At present, the industrial production is mainly used in the suspension polymerization and bulk polymerization method.
1. The bulk polymerization method is that styrene monomer into the pre-reactor, and then add a small amount of additives and initiator, at 95 ~ 115 ℃ heating and stirring for pre-polymerization, to be converted to 20% to 35%, and then into the Continuous polymerization is carried out in a tower reactor with a stirrer. The polymerization temperature is increased to about 170 ° C to achieve complete conversion. A small amount of unreacted styrene is released from the top of the column and recycled. The polymer is continuously discharged from the bottom of the column and extruded into pellets to produce the finished product.
2. Suspension polymerization method Styrene-based monomer, water as a medium, gelatin or starch, polyvinyl alcohol, hydroxyethyl cellulose and other protective adhesive or magnesium carbonate, magnesium silicate, calcium phosphate and other insoluble inorganic salts are dispersed And maleic anhydride-styrene copolymer sodium salt as the dispersing agent, with benzoyl peroxide as the initiator, at about 85 ℃ to initiate polymerization. It is possible to carry out high-temperature polymerization at a high temperature of 100 ° C or higher in a high-pressure polymerization reactor without using an initiator. The polymer is washed, separated and dried to give a colorless and transparent bead-like resin.