| 摘要 |
PROBLEM TO BE SOLVED: To produce the above spherical particle in excellent productivity in a short impregnation time of a blowing agent without causing blocking, by impregnating a specific polystyrene-based resin particle with the blowing agent. SOLUTION: In obtaining the above particle having >=0.5mm and <=3.0mm average particle diameter by impregnating (A) a conjugated diene-based polymer component-containing polystyrene-based resin particle with (B) a blowing agent, a particle which is obtained by melting the component A in an extruder by heating, extruding the melt from an extrusion die at 2,500-10,000 (1/second) shear rate and 150-700 poise apparent viscosity of the resin at a die land part into water and simultaneously cutting by a die face is used as the resin particle before impregnation with the component B. Preferably the content of the conjugated diene component of the component A is 3-20wt.%, the intrinsic viscosity of the polystyrene-based component phase at 30 deg.C is 0.6-0.9 and the sphericity of the objective particle is preferably 1.0-1. |
