| 摘要 |
PURPOSE:To produce foamable particles which provide low-density foamed products without overfilling in molding, by effecting, in an aqueous medium, both the reaction of styrene/maleic anhydride copolymer resin particles with a compound containing active hydroxyl groups and the impregnation of the resin particles with a blowing agent. CONSTITUTION:Styrene/maleic anhydride copolymer resin particles are dispersed in water. To the resulting dispersion, are added a compound containing at least two active hydroxyl groups, in an amount corresponding to at least 0.025 mol% of the anhydride groups contained in said resin, and a volatile blowing agent. Then, the esterification and impregnation with the blowing agent are effected. With respect to said styrene/maleic anhydride copolymer resins, those having maleic anhydride contents of below 2wt% do not provide excellent heat resistance and those having maleic anhydride contents above 25wt% are difficult to impregnate with a blowing agent. As the compounds having at least two active hydroxyl groups, those having two hydroxyl groups are particularly preferred. |
