METHOD FOR PRODUCING PREFOAMED PARTICLE OF STYRENE-MODIFIED POLYETHYLENE RESIN AND FOAM MOLDED ARTICLE OF STYRENE-MODIFIED POLYETHYLENE RESIN

PROBLEM TO BE SOLVED: To provide a method for producing prefoamed particles of styrene-modified polyethylene resin by a depressurizing foaming method to give the prefoamed particles suppressed fluctuation of the foaming ratio.SOLUTION: The method for producing the prefoamed particles of the styrene-modified polyethylene resin comprises: a step (a) to disperse styrene-modified polyethylene resin particles in an aqueous dispersing medium together with a dispersant in a pressure vessel, and to put a foaming agent into the pressure vessel under stirring to rise the temperature of the vessel; a step (b) to impregnate the foaming agent to the styrene-modified polyethylene resin particles; and a step (c) to discharge a mixture containing the styrene-modified polyethylene resin particles and the aqueous dispersion medium to a space with a lower pressure than the pressure in the pressure vessel by opening an end of the pressure vessel, wherein a foaming agent same as the foaming agent used in the step (a) is additionally introduced into the system in the step (c).