浅谈PVC树脂中残留VCM脱吸的影响因素及改进措施

Introduction to factors influencing the desorption of residual VCM from PVC resin and improvement measures for it

通过PVC树脂中VCM脱吸机理和影响因素的分析 ,提出了改进措施 :(1)减少分散剂用量、加入低分子质量、低醇解度的聚乙烯醇 (LL - 0 2 ) ;(2 )在聚合配方中添加NH3·H2 O和NH4 HCO3;(3)当聚合釜压力降为 0 .15～ 0 .2 0MPa时加终止剂 (此时转化率在 85 %以下 )终止反应。采取改进措施后 ,改进了PVC树脂颗粒的皮膜结构 ,使PVC树脂中残留的VCM含量小于 5× 10 -6,达到了无毒级PVC树脂的要求。

Through analyzing on the mechanism of the desorption of VCM from PVC resin and its ,influencing factors the following improvement measures are proposed:(1)reducing the using amount of dispersant agents,adding poly(vinyl alcohol) (LL-02) with low molecular weight and low alcoholysis degree;(2)adding NH 3·H 2O and NH 4HCO 3 to the polymerization composition;and (3)adding terminator when pressure reduces to 0.15～0.20 MPa (with conversion ≤85%) to terminate polymerization reaction.After modification,the surface structure of PVC resin particle is improved,the residual VCM content in PVC resin reduces to less than 5 ppm,meeting the requirement of non-toxic class resin.