| 摘要 |
Rigid cellular materials exhibiting closed cells and based on polyvinyl chloride are prepared by homogeneously mixing polyvinyl chloride, a heat-decomposable blowing agent, an organic polyisocyanate and a bituminous substance; heating the mixture in a mould to decompose the blowing agent, to expand and gel the polyvinyl chloride and to melt the bituminous substance; cooling the expanded material under pressure and removing it from the mould; and placing the expanded material in contact with hot water or water vapour to effect further expansion. In an example, expanded material is prepared from a paste comprising polyvinyl chloride, asphalt, toluene diisocyanate and di-iso-azobutyronitrile.ALSO:Rigid cellular materials exhibiting closed cells and based on polyvinyl chloride are prepared by homogeneously mixing polyvinyl chloride, a heat-decomposable blowing agent, an organic polyisocyanate and a bituminous substance; heating the mixture under pressure in a mould to decompose the blowing agent, to expand and gel the polyvinyl chloride and to melt the bituminous substance; cooling the expanded material under pressure and removing it from the mould; and placing the expanded material in contact with hot water or water vapour to effect further expansion. In an example, expanded material is prepared from a paste comprising polyvinyl chloride, asphalt, toluene diisocyanate and di-isoazobutyronitrile. |
