PURPOSE: The titled resin particles excellent in strength, elastic recovery, etc., and suitable as a cushion material, etc., prepared by extruding a resin through an extruder to give a molecular orientation along the longitudinal direction, comminuting the extrude into slim particles, impregnating the particles with a blowing agent and pre-expanding the particles.
CONSTITUTION: A thermoplastic synthetic resin such as polyethylene or polypropylene is heat-molten within an extruder and extruded through the nozzle into fiber. This fiber is stretched to give a molecular orientation such that the ratio of the molecular orientation in the longitudinal direction α to the molecular orientation in the direction crossing the longitudinal direction β (α/β) is 1.2W4. Next, the stretched fiber-form resin is comminuted into spheroidal or rod- like particles of which the length in the longitudinal direction is 1.2W5 times the longest length in the direction crossing the longitudinal direction. The obtained particles are impregnated with a blowing agent such as dichlorodifluoromethane and pre-expanded to form the purpose resin particles.
HIROZAWA KUNINORI
KUWABARA HIDEKI
SHIMADA SUMIO
