The invention belongs to the technical field of foamed
polypropylene, and relates to a preparation method of foamed
polypropylene beads, which comprises the following steps: (1) adding
polypropylene particles, a dispersion medium, a dispersing agent and a dispersing aid into a closed high-pressure-resistant kettle, and conducting stirring to form a dispersion
system; (2) conducting heating to a certain temperature, and conducting filling with a certain amount of CO2; and (3) releasing the dispersion to normal pressure to obtain foamed polypropylene beads, conducting washing with cleaning water, conducting dehydrating, and conducting
drying to obtain a foamed polypropylene bead finished product. The polypropylene particles comprise the following components in percentage by weight: 94 to 99.94 percent of polypropylene, 0.01 to 2 percent of a
crystallization nucleating agent, 0.02 to 4 percent of an
organophosphate compound and 0.03 to 0.3 percent of a
cell nucleating agent. The polypropylene particles used in the invention contain
organophosphate compounds, and have the effect of inhibiting the particles from
caking in a kettle or the beads from
caking outside the kettle in the high-temperature and high-pressure kettle type foaming process, so that the use amount of a dispersing agent can be reduced, the content of attachments on the surface of the foamed polypropylene bead finished product is lower than 200ppm, and a
water vapor molded part is lower in
sintering pressure and excellent in apparent quality.