POLYPROPYLENE RESIN FOAMED PARTICLES AND METHOD FOR PRODUCING SAME

• Main Authors: MOCHIZUKI, Yoshiyuki, ITOI, Akihiro
• Format: Patent
• Language: English; French; German
• Published: 26.02.2020
• Subjects: AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F,C08G; CHEMISTRY; COMPOSITIONS BASED THEREON; GENERAL PROCESSES OF COMPOUNDING; METALLURGY; ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; WORKING-UP

Provided is polypropylene-based resin expanded particles which make it possible to obtain a gray in-mold foamed molded product whose color is uniform and excellent in color tone. The polypropylene-based resin expanded particles, which are uniform and excellent in color tone, are produced by (i) dispersing polypropylene-based resin particles and carbon dioxide into an aqueous dispersion medium in a closed vessel, the polypropylene-based resin particles containing carbon black and at least one selected from magnesium hydroxide and magnesium carbonate, the carbon black and the at least one selected from magnesium hydroxide and magnesium carbonate having been added to a polypropylene-based resin; (ii) heating a dispersion slurry obtained in (i) to a temperature not less than a softening temperature of the polypropylene-based resin particles and pressurizing the dispersion slurry; and (iii) then releasing the polypropylene-based resin particles into a region at a pressure lower than an internal pressure of the closed vessel.