新型气固相法CPVC制备工艺的研究

以经力化学改性的PVC树脂为原料,通过低温等离子体生成自由基Cl.,在气固流化床中制备CPVC,考察了输入电压、体系压力、氯气流量、反应时间、惰性气体等因素对CPVC氯含量的影响,讨论了反应体系温度的控制,并采用扫描电镜对CPVC产物进行了表征。结果表明:①经过力化学改性后的PVC树脂颗粒粒径有较大程度的减小,比表面积增大,且树脂皮膜和结晶区被破坏,有利于氯化反应;②较佳的制备工艺条件为输入电压900V,常压,氯气流量3L/min,反应时间30min,不加入氩气;③输入电压是影响CPVC氯含量的主要因素;④当CPVC的含氯质量分数超过68%后,反应速率快速下降;⑤试验制得的CPVC呈现疏松的不规则雪片状结构,初级粒子、聚集体、亚颗粒等多层次的结构已经完全消失,皮膜也被彻底破坏,比表面积较大。

Research on the preparation process of CPVC by a novel gas-solid phase method

By using mechanochemically modified PVC resin as raw materials and generating free radical CI · through low-temperature pasma, CPVC was prepared in a gas-solid fluidized bed. Influences of input voltage, pressure, chlorine flow, reaction time and inert gases on the chlorine contents in CPVC were investigated. The control on reaction temperature was discussed, and SEM was used to characterize CPVC products. The results showed that： （1） mechanochemically modified PVC had characteristics of greatly decreased particle size, increased specific surface area and fractured skin and crystalline structure, was apt to be chlorinated; （2） the better process conditions were as follows： input voltage 900 V, chlorine flow 3 L/min, reaction time 30 min, no argon adding; （3） input voltage was the main factor of influencing the chlorine contents in CPVC;（4） the reaction rate decreased abruptly after the chlorine contents in CPVC were more than 68 wt% ; （5） the CPVC obtained showed loose irregular flake structure, the multi-layered structure composed of primary particle, aggregate and sub-particle had completely disappeared, its skin was also completely de- stroyed, and the specific surface areas were bigger.