| 摘要 |
PROBLEM TO BE SOLVED: To provide polypropylene resin pre-expanded particles that gives an expansion-molded product having a high expansion magnification, a glossy surface and a small dimensional shrinkage even when an inorganic gas expanding agent is used. SOLUTION: The polypropylene resin pre-expanded particles are obtained by dispersing polypropylene resin particles in an aqueous dispersion medium in a pressure-resistant container, introducing an inorganic gas as an expanding agent, heating and pressurizing the container to a temperature equal to or higher than the softening temperature of the polypropylene resin particles, and releasing the particles to a zone at a pressure lower than the inner pressure of the pressure-resistant container. The pre-expanded resin particles contain, with respect to 100 parts by weight of a polypropylene resin, (a) 0.001 to 0.5 part by weight of an inorganic substance, water of crystallization of which shows a dehydration start temperature of 200°C or higher, (b) 0.005 to 0.5 part by weight of a fatty acid amide, (c) 0.0001 to 0.5 part by weight of a silicate compound, and (d) 0.005 to 0.5 part by weight of a trivalent organic phosphorus compound. COPYRIGHT: (C)2010,JPO&INPIT |
