| 摘要 |
PURPOSE:To contrive an improvement in working efficiency, by turning repelletized resin particles into a spherized and cross-linked states by heat-treating them and then foaming treatment is performed. CONSTITUTION:Raw material resin is heated, fused and extruded within an extruder 1, cut off by a rotary blade 11 in a dispersion medium and repelletized into particles of a predetermined size. The particles from which the dispersion medium separated are heat-treated within a heating tank 3 and spherized and/or crosslinked. Heat treatment is performed at the temperature above the softening point. Then the resin particles are introduced into a first foaming tank 4, agitated under existence of a foaming agent, heated and held at the temperature above the softening point of the resin particles, discharged under an atmosphere whose pressure is lower than the inside of the foaming tank 4 and made to foam. As for base board resin of synthetic resin particles, low density polyethylene or an ethylene-propylene random copolymer is desirable. |
