EXPANDED STYRENE RESIN BEADS AND MOLDED OBJECT FORMED FROM EXPANDED STYRENE RESIN BEADS

摘要

Expanded styrene resin beads from which an in-mold expanded-bead molding having excellent fusion bonding among the expanded beads can be produced through a short cooling time by in-mold molding and which can attain an improvement in molding cycle. The expanded styrene resin beads are made of a styrene resin as the base resin and have an average bead diameter of 0.5-10 mm and an apparent density of 0.013-0.15 g/cm3. The expanded beads are characterized in that the expanded beads each has many dimples having a maximum diameter of 5-100 µm in the surface and that when the expanded beads are secondarily expanded under the conditions of a heating steam temperature of 107°C and a heating time of 120 seconds, then the secondary expansion ratio determined by dividing the apparent density of the expanded beads before the secondary expansion (g/cm3) by the apparent density of the expanded beads after the secondary expansion (g/cm3) satisfies the relationship (1). Secondary expansion ratio = -7.00 x {apparent density of expanded beads before secondary expansion (g/cm3)} + 1.61 (1)