PURPOSE: To obtain foamable polyolefinic resin particles excellent in fusibility by heating polyolefinic resin particles, an expanding agent, a suspending agent, and water under stirring in a closed pressure vessel, and releasing the resultant dispersion into a reduced pressure atmosphere, followed by washing with a specific solution.
CONSTITUTION: This foamable polyolefinic resin particles are obtained by heating polyolefinic resin particles, an inorganic suspending agent (an inorganic weak acid salt of an alkaline earth metal), and water under stirring in the presence of an expanding agent to a softening temperature of the resin or above in a closed pressure vessel, releasing the contents of the vessel into an atmosphere having a lower pressure than in the vessel, and washing the resulting contents with an aqueous solution of a mono- or bi-valent mineral acid. The polyolefinic resin particles may preferably be those containing an inorganic filler. The inorganic suspending agent may, for example, include tribasic calcium phosphate and calcium pyrophosphate.
OKUWA TERUYA
YAGI TOSHIO
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