PROCESS FOR PRODUCING CRACKING-RESISTANT AND IMPACT-RESISTANT POLYSTYRENE Russian patent published in 2007 - IPC C08F279/02 C08L25/04 

FIELD: polymerization processes.

SUBSTANCE: cracking- and impact-resistant polystyrene is prepared via bulk prepolymerization or prepolymerization in presence of inert solvent accomplished by stirring solution of blended butadiene rubber and modifying rubber in styrene at elevated temperature until phase inversion in presence of molecular mass regulator is completed while initiating polymerization by organic peroxides or thermally, after which polymerization process in bulk or in aqueous suspension is completed. Specifically, modifying rubber is ethylene-propylene-diene rubber having Mooney viscosity (ML 1+8, 125°C) 26-25 taken in amount 1.0-1.5% based on the total weight of reactants, and prepolymerization of solution of blended butadiene and modifying rubbers in styrene results in forming rubber particles having average size 3.5 to 6.0 μm and characterized by content of gel 26-30% and gel swelling index in final polymer 11-16, whereas prepolymerization process is carried out to achieve conversion of styrene 24-35 wt %.

EFFECT: achieved high cracking resistance while preserving high impact resistance and good processing ability.

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