石蜡对四氟乙烯分散聚合的影响

Influence of Paraffin on the Dispersion(Emulsion) Polymerization of Tetrafluoroethylene

分析了稳定剂石蜡对四氟乙烯分散聚合的聚合速度、分子量、固含量和初级粒径的影响,表明石蜡对聚合速度和分子量有正相关的影响,能够提高固含量并改善初级粒子大小和分布;同时讨论了四氟乙烯分散聚合系统中合适的石蜡含量,即水中石蜡的质量浓度20 g/L既能够满足聚合系统的需要而成本又较低。探讨了石蜡作为稳定剂的作用机理,并确定了石蜡的选用标准,即熔点40～65℃,碳原子数不少于12,杂质摩尔分数不超过引发剂的30%,此时易去除和回收石蜡。并指出树脂中微量石蜡的残留对于成型制品的危害,认为氟聚合物行业保证树脂质量品级的研究重点为石蜡品种的选择和微量残留的去除。

The effects of stabilizer paraffin on the polymerization rate, molecular weight, solid content and primary particle size of tetrafluoroethylene (TFE) dispersion polymerization were analyzed. The results showed that paraffin had a positive correlation with the polymerization rate and molecular weight, and could increase the solid content and improve the size and distribution of primary particles. The suitable paraffin content in PTFE dispersion polymerization system was discussed, resulting that when the mass concentration of paraffin in water was 20g/L, could meet the needs of the polymerization system and had low cost. Mechanism of the paraffin as the stabilizers was discussed, then determined the paraffin selection standard, melting point was 40~650℃, and the carbon atom number was not less than 12, the mole fraction of impurities was not more than 30% of the initiator, at this time, the paraffin removed and recycled easily. The harm of trace paraffin residues in the resin to the molding products was pointed out. The research emphasis of the fluoropolymer industry to ensure the quality of the resin was the selection of paraffin varieties and the removal of trace residues.