SSA 分析技术在双向拉伸聚丙烯专用料生产过程中的应用

采用连续自成核退火法(SSA)对几种不同双向拉伸聚丙烯(BOPP)树脂进行了等规度及等规序列分布表征,研究了其结晶行为与成膜稳定性之间的关系,据此分析了中国石油兰州石化公司30万t/a聚丙烯装置初期所产BOPP产品在使用过程中存在易破膜问题的原因,并进行了装置聚合工艺参数的优化.结果表明,BOPP树脂的成膜稳定性取决于其等规度分布情况,即高等规度组分含量应较低,低等规度组分含量应较高,峰高比值(Ipeak1/Ipeak2)以小于1为宜；随着催化剂与外给电子体质量比(T/D)的增大,BOPP树脂的高等规度组分含量逐渐降低,中、低等规度组分含量相对上升,晶片厚度变薄,分布加宽,成膜性能得以改善.

Application of SSA analysis technique in biaxially oriented polypropylene specialty resin production

The isotacticity and its sequence distribution of several biaxially oriented polypropylene(BOPP) specialty resins were characterizated by successive self-nucleation annealing(SSA) method,and the relationship between crystallization and film forming performance was researched.On the basis of this,the cause for film breaking of BOPP resin manufactured in a 300kt/a polypropylene unit of Lanzhou Petrochemical Company occurred during its extruding was analyzed,and the process parameters of the polymerization were optimized.The results showed that the film forming stability of BOPP resin was dependent on the isotacticity sequence distribution,that was the content of high isotacticity molecules needed to be decreased,and the content of low isotacticity molecules needed to be increased.The IPeak1/IPeak2 ratio should be less than 1.With increasing the mass ratio of catalyst to external electron donor(T/D),the content of high isotacticity molecules decreased,the content of low and medium isotacticity molecules inceased,the lamellar became thinner,the isotacticity sequence distribution became broader,and the performance of film forming was improved.