CONTINOUS POLYMERIZATION PROCESS OF RUBBER-MODIFIED STYRENIC RESIN WITH GOOD FALLING DART IMPACT

摘要

Provided is a method for preparing continuously a rubber modified polystyrene resin which contains a dispersive rubber particle whose particle size distribution has a trimodal shape, and has a high grafting efficiency, a narrow distribution of molecular weight and excellent Izod impact strength and practical impact strength. The method comprises the steps of reacting a liquid supply material composition comprising three different kinds of synthetic butadiene polymers dissolved in a styrene-based monomer in a first reactor at 90-130 deg.C for 1-2 hours before the phase transition point to prepare a first polymer having a monomer conversion rate of 5-15 %; continuously injecting the first polymer into a second reactor to polymerize them at 110-145 deg.C for 1-2 hours to prepare a second polymer having a monomer conversion rate of 15-30 %; continuously injecting the second polymer into a third reactor to polymerize them at 140-160 deg.C for 0.5-1.5 hours to prepare a third polymer having a monomer conversion rate of 30-60 %; continuously injecting the third polymer into a fourth reactor to polymerize them at 150-180 deg.C to prepare a fourth polymer having a monomer conversion rate of 60-90 %; and injecting the fourth polymer into a volatile material remover to remove the unreacted monomer and a solvent. Preferably the three different kinds of synthetic butadiene polymers comprises 15-35 wt% of a styrene-butadiene block copolymer, 50-85 wt% of a low cis-polybutadiene rubber, and 15-35 wt% of a high cis-polybutadiene rubber.