偏氟乙烯乳液聚合的气液传质效果影响因素研究

推导了表征气液传质效果的K值计算方法,并研究了聚合釜装填量、搅拌桨型和转速等因素对气液传质效果的影响。结果表明,随着聚合釜装填量和搅拌转速的增大,K值增大,气液传质效果提高;在搅拌转速大于500r/min的情况下,桨型采用上层二叶平桨、下层二叶斜桨的方式明显比单层的二叶斜桨或二叶平桨的K值大,气液传质效果好。确定了5L釜偏氟乙烯(VDF)乳液聚合必需的良好搅拌效果的条件:装填量3L,搅拌转速700r/min,桨型采用上层二叶平桨和下层二叶斜桨;VDF聚合速率达到115g/(L·h),合成出固体质量分数20%、粒径分布窄、稳定性好的聚偏氟乙烯(PVDF)乳液。

Studies on the influencing factors of gas-liquid mass transfer in vinylidene fluoride emulsion polymerization

The calculating method of Kvalue indicating gas-liquid mass transfer effects is carried out. The effects of type and speed of agitator, and liquid volume on the Kvalue are investigated. The results show that the Kvalue increases with increasing of the liquid volume and the agitator speed, so the mass transfer effects improve. When the speed of agitator exceeds 500r/min, the mass transfer effects of agitator combining with flat and inclined paddle are better than those of monolayer of flat or inclined paddle. The optimum conditions for vinylidene fluoride emulsion polymerization in the 5L reactor are carried out as follows: liquid volume 3L, agitation speed 700r/min, and using combining agitator, so the vinylidene fluoride emulsion polymerization speed can be up to 115g/(L·h), the mass fraction of latex is 20%, and the polyvinylidene fluoride emulsion with narrow particle diameter distribution and good stability is then obtained.