Expandable modified resin beads, expanded modified resin beads, and foamed molded article formed from expanded modified resin beads

A method for producing an expandable modified resin bead, comprising a modified resin as a base resin and a physical blowing agent, wherein the modified resin comprises a continuous phase comprising an olefin resin and a dispersion phase, dispersed in the continuous phase, comprising a styrene resin,

• the method comprising:
• impregnating styrene-based monomers into a nuclear particle comprising the olefin resin and a dispersion diameter-enlarging agent capable of enlarging a volume average diameter of the dispersion phase;
• polymerizing the styrene-based monomers to obtain a modified resin bead having a continuous phase and a dispersion phase;
• and
• impregnating the resin bead with a physical blowing agent during or after polymerization of the styrene-based monomers,
• wherein
• the dispersion diameter enlarging agent comprises at least one substance selected from the group consisting of a methyl methacrylate-styrene copolymer, polystyrene, a styrene-based elastomer selected from a styrene-butadiene-styrene block copolymer, a styrene-isoprene-styrene block copolymer, and a hydrate of these block copolymers, rubber modified polystyrene, an ABS resin, an AES resin, polyvinyl chloride, and polyvinylidene chloride, in which the substance is different from the styrene resin of the dispersion phase.