PRE-EXPANDED POLYETHYLENE BEADS AND PROCESS FOR THE PRODUCTION THEREOF

摘要

Pre-expanded beads of a non-cross-linked polyethylene which comprise a resin mixture comprising a high-pressure low-density polyethylene, a linear low-density polyethylene and a linear high-density polyethylene as the base resin and which exhibits a single-peak V-shaped endothermic melting curve as determined by the use of a differential scanning calorimeter (DSC) where the temperature difference represented by the segment DE is 15 DEG C or above, when the peak point of the V-shaped curve is taken as A, the point at which the perpendicular drawn from A toward the temperature axis intersects the base line of the endothermic curve is taken as B, and the two points at which the straight line running parallel to the temperature axis and passing through the point C at which the segment AB of the above perpendicular is interiorly divided at a ratio of 9 : 1 intersects the endothermic curve are taken as D and E, respectively. The pre-expanded beads are usable for forming moldings having complicated shapes in molds and satisfy a necessary compression strength even when highly expanded.