PRODUCTION OF FOAMED GRAIN OF POLYMER

摘要

PURPOSE:To obtain foamed grains of polymer having high foaming magnification and reduced in dispersion by using polymer grains containing an inorganic material as polymer grains and simultaneously feeding a mixed gas of carbon dioxide and inorganic gas and foaming the polymer grains while applying back pressure. CONSTITUTION:Polymer grains containing an inorganic material is dispersed into a dispersing medium in the presence of carbon dioxide in a closed vessel and heated at softening temperature of the grains or above to impregnate carbon dioxide into the polymer grains. Then the grains and dispersing medium are released from the vessel into low-pressure atmosphere while applying back pressure using a mixed gas containing carbon dioxide and inorganic gas having pressure higher than vapor pressure of carbon dioxide in the vessel at a mixed ratio of 3:7-9.5:0.5 to foam the grains.