| 摘要 |
PURPOSE:To obtain expanded particles with hardly any residual expanded gas for insulating materials of LPG stockpiling tanks, by repelletizing styrene- maleic anhydride copolymer resin particles, impregnating the resultant pellets with a readily volatile foaming agent, coating the pellets with a triester, expanding the pellets while heating and treating the expanded pellets at a high temperature. CONSTITUTION:(A) A styrene-maleic anhydride copolymer resin particles obtained by a bulk polymerization method are repelletized. (B) A readily volatile foaming agent, preferably propane, butane or pentane is then impregnated into the resultant pellets at 50-70 deg.C, preferably about 60 deg.C. (C) The surfaces of the obtained expandable resin particles are subsequently coated with 0.1-1% triester consisting of glycerol and a 16-18C fatty acid, e.g. hardened soybean oil or oleic acid. (D) The pellets are heated to provide expanded particles. (E) The expanded particles are then treated at a high temperature of >=80 deg.C, preferably 80-110 deg.C to produce expanded particles for insulating materials of LPG stockpiling tanks with hardly any residual blowing gas.
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