| 摘要 |
PURPOSE:To obtain a high-bulk density vinyl chloride polymer, by polymerizing vinyl chloride in a vapor phase by the use of two radical catalysts having a 10-hour half-value temperature difference of at least a specified value. CONSTITUTION:A vinyl chloride (co)polymer is obtained by charging an autoclave with a mixture containing (i) a high-temperature-active radical catalyst and (ii) a low-temperature-active radical catalyst and having a 10-hour half-value temperature difference of at least 5 deg.C (preferably, 10-50 deg.C), an organic solvent which does not dissolve a vinyl chloride polymer (e.g., n-pentane); heating the mixture; continuously feeding, to this mixture, a vinyl chloride monomer and, if necessary, other monomers; and polymerizing the reaction mixture in a vapor phase at 40-80 deg.C under a polymerization pressure below the saturated vapor pressure of the vinyl chloride monomer. EFFECT:The polymer thus-produced is excellent in storage stability, sanitariness, handling and processability. |
