PP2400的流变性能对BOPP成膜性能的影响

本文研究了ＰＰ２４００的流变性能对其ＢＯＰＰ成膜性能的影响。通过与进口ＰＰ进行对比试验，发现ＰＰ２４００的分子量高、粘度大、熔体强度较大。正是由于分子量较高，导致粘度较高，ＰＰ２４００料的塑化度减小，影响了塑化的均匀性，从而造成挤出性能的恶化。指出问题的关键在于如何处理好粘度与熔体强度之间的平衡关系。掺混进口ＢＯＰＰ料，可降低体系的挤出粘度，提高塑化的均匀性，使厚片的厚度与宽度控制精确，并使厚片内应力均匀，对后续成膜工艺相当重要。加大口模长度，延长ＰＰ分子链的松弛时间对改善厚片质量进而提高成膜性能有所裨益。适当提高挤出厚片时的挤出温度，将能改善体系的流动性能，提高塑化的均匀性，减小出口膨胀率

The Effect of the Rheological Property of PP2400 on BOPP Film Formation

The effect of the rheological property of PP2400 on BOPP film formation is studied in this paper.It was found by comparison with imported PP that PP2400 had high molecular weight,apparent viscosity and melt strength.Precisely because of the high molecular weight,the viscosity increased and the plastification of PP2400 decreased,the uniformity of the plastification was thus being affected and made the extrusion processability bad.The keypoint consists in striking a proper balance between the viscosity and melt strength.Blending with imported BOPP compound could decrease the extrusion viscosity of the blend system,increase the uniformity of plastification,make the thickness and width of the sheet under control,and the internal stress of the sheet was thus more uniform,being important for succeeding film formation.To increase the length of mouthpiece and prolong the relaxation time of PP molecular chain would improve the quality of the sheet and the film formation.A suitable increase of the extrusion temperature for the sheet would improve the flowability of the blend system and the uniformity of the plastification,and decrease the outlet expansion ratio.