| 摘要 |
PROBLEM TO BE SOLVED: To obtain a styrene-based foamable resin particle not requiring aging, having slight change of a cell of a preexpanded styrene-based foamable resin particle, namely, hardly being affected by a storage condition and to provide a method for producing the styrene-based foamable resin particle. SOLUTION: This styrene-based foamable resin particle has <=100 voids/mm<2> at a distance of <=0.1mm from the surface in the radius direction on a section passing through the vicinity of the center of the styrene-based foamable resin particle within 0.1mm in the radius direction. In a method for producing the foamable resin particle by suspending a styrene-based monomer in an aqueous medium in the presence of a polymerization initiator and a suspending agent and adding a blowing agent to the suspension, an alkali metal persulfate or ammonium persulfate is added in such an amount as to become 0.5-30ppm based on the aqueous medium to the aqueous medium at the conversion ratio of the monomer of 0-30%. At a point of time when the conversion ratio of the polymerization is >=30%, an electrolyte is added in such an amount as to become 0.02-5.0mol/L based on the aqueous medium to the suspension to produce the objective styrene-based foamable resin particle. |
