Styrene, Rubber, Ethyl benzene, Zinc Stearate and Liquid Paraffin are the starting materials used for high impact polystyrene manufacturing. Solution polymerization technique is used to polymerize styrene in ethyl benzene solvent and chain transfer agent. Rate of reaction increases due to the addition of rubber between the reaction stages. Therefore, the solvent present in this reaction slows the reaction and causes considerable chain termination. Styrene is polymerized in cascade of reactors in stepwise because removal of heat is one of the main problems.
HIPS (High impact polystyrene) plant can be divided into following sections
• Packing Section.
• This section again consists of
• Feed Preparation,
• Feed Storage
• Reactors (Polymerization).
High Impact Polystyrene manufacturing process flow diagram brief description:
Five continuous stirred tank reactors are used for the handling the polymerization operation. In which three are used for pre-polymerization and other two are used for improve polymerization. Unreacted styrene is removed from the product stream in separators and recycled. Preheater is used for heat recovery from the hot polymer. Impurities like high boiling fractions are removed by the devoltalizer equipment. Finally, the polymer is cooled and pelletized into solid pellets.