| 摘要 |
PURPOSE:To obtain hollow spheres of pitch having broad particle size distribution at a low cost, by pulverizing pitch mixed with a foaming agent and thermally expanding the pulverized pitch in a specific liquid heat medium, thereby enabling expansion of pitch in high heat-transmission efficiency while preventing the fusion of pitch spheres. CONSTITUTION:The objective hollow pitch spheres can be produced by pulverizing a coal-based or petroleum-based pitch mixed with a foaming agent (e.g. a solvent-type foaming agent such as benzene, toluene, xylene, etc., or decomposition-type foaming agent such as azobisisobutyronitrile) and heating and foaming the pulverized pitch in a heat-medium which is liquid at the foaming temperature and essentially free from compatibility to said pitch and foaming agent. USE:High-temperature heat-insulation material for electric furnace, furnace material for nuclear reactor, filler for electrically conductive plastics, composite material of metal and inorganic substance, filler for molding compound, etc.
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