To produce a wide range of high-impact polystyrene (HIPS) with well-balanced mechanical properties and processability via the continuous bulk polymerization process using Toyo Engineering Corp. (TOYO)/Mitsui Chemicals Inc. technology. The process provides a swing production feature and is also capable of producing general purpose polystyrene (GPPS).
Styrene monomer, ground rubber chips and small amount of additives are fed to the rubber dissolver (1). The rubber chips are completely dissolved in the styrene. This rubber solution is sent to a rubber-solution-feed tank (2). The rubber solution from the tank is sent to the prepolymerizer (3) where it is prepolymerized, and the rubber morphology is established.
The prepolymerized solution is then polymerized in specially designed reactors (4) arranged in series. The polymerization temperature of the reactors is carefully controlled at a constant level to maintain the desired conversion rate. The heat of the polymerization is easily removed by a specially designed heat-transfer system.
The polymerization product, a highly viscous solution, is preheated (5) and transferred to the devolatilizers (6). Volatile components are separated from the polymer solution by evaporation under vacuum. The residuals are condensed (7) and recycled to the process. The molten polymer is pumped through a die (8) and cut into pellets by a pelletizer
Licensor: Toyo Engineering Corp. (TOYO)/Mitsui Chemicals Inc.