聚丙烯硬弹性膜的挤出流延工艺及拉伸成孔性

以某进口均聚聚丙烯(PP)(PP1)为原料,通过挤出流延工艺制备了PP1硬弹性膜并在130℃下对其进行热处理,研究了挤出温度、流延辊转速及温度、热处理温度和时间等工艺参数对PP1硬弹性膜弹性回复率的影响,得到了最佳工艺条件,即挤出温度为195℃、流延辊温度及转速分别为90℃,26 r/min,热处理温度和时间分别为145℃,30 min。将该工艺应用于分子量及其分布与PP1基本相似的国产PP(PP2),发现由此工艺制备的PP2硬弹性膜的弹性回复率可达94.6%,与PP1硬弹性膜相差不大。通过冷热单向拉伸将PP1和PP2硬弹性膜制备成微孔膜,发现两者具有相似且优异的微孔结构。在此基础上,通过扫描电子显微镜研究了冷热拉伸工艺参数对PP2微孔膜拉伸成孔性的影响。结果表明,当冷拉伸倍数为15%,热拉伸倍数为100%,冷热拉伸速率均为50 mm/min时,制备的PP2微孔膜形成了完整规则的多孔结构。

Extrusion Casting Process and Micro-pore Stretching Forming of PP Hard Elastic Membrane

Taking some imported polypropylene (PP) (PP1) as raw material,PP1 hard elastic membrane was prepared by us-ing extrusion casting process and treated at 130℃. The relationships between elastic recovery rate of PP1 membrane and process parameters (such as extrusion temperature,casting roller temperature and rotational speed,annealing temperature and duration) were investigated to obtain optimum processing conditions as 195℃ for extrusion temperature,90℃ for casting roller temperature and 26 r/min for its rotational speed and annealing at 145℃ for 30 min. The optimum processing conditions were used for domestic PP (PP2) with similar molecular weight and distribution as PP1,then PP2 hard elastic membrane was prepared. It is found that the elastic recovery rate of PP2 membrane is 94.6%,which is similar with that of PP1 membrane. Microporous membrane of PP1 and PP2 were prepared by cold-hot stretching,which showed similar and excellent microporous structure. Furthermore,scanning elec-tronic microscopy was utilized to study the influences of cold-hot stretching process on porous property of PP2 membrane. It is found that an uniformed,well-developed microporous structure can be achieved for PP2 membrane when cold stretching ratio is 15%,hot stretching ratio is 100% and cold-hot stretching ratio is 50 mm/min.