Improvement of polyolefin film by alternately stacking different kinds of thin, oriented polymers

制备了取向等规丙烯(IPP)和聚乙烯(PE)交替堆积的复合膜，但其拉伸模数和强度等物理性能不高，难以在实际应用中使用。为了改善其性能，我们发现有三个主要障碍需要克服：第一，需要使iPP和PE各自的层数尽可能薄，在拉伸前它们的单层数可能小于0.1 mm。在本研究中，通过交替堆积所谓的IPP和PE的凝胶来制备堆积膜，这些凝胶是通过结晶这些聚合物从溶液中形成的。当IPP和PE凝胶交替堆积时，各自的凝胶表面相当粗糙，因此很难使各层的厚度均匀，特别是当每层都很薄的时候。由于IPP和PE的拉伸温度不同，选择合适的温度同时拉伸较高是一个难题。结果表明，在130ﾟC-140ﾟC的温度范围内，两种聚合物都能同时顺利拉伸。第二个需要解决的问题是选择和控制合适的拉伸温度。另一个需要克服的问题是将所制备的堆叠凝胶膜拉伸得更高。这与上述两个问题密切相关。

The composite films in which oriented isotactic propylene (iPP) and polyethylene (PE) were alternately stacked in layr were prepared, but their physical properties such as tensile modulus and strength were not high enough to be endurable in practical use. To improve the properties, we found there are three main hurdles to overcome.Firstly, it is needed that respective layrs of iPP and PE are as thin as possible, maybe their single layr is less than 0.1 mm before drawn. In the present study, a stacked film was prepared by piling alternately the so-called 'gels' of iPP and PE which were made by crystallization these polymers from solution. When gels of iPP and PE were alternately stacked, surfaces of respective gels were rather rough, and hence it was very difficult to make the thickness of individual layrs uniform, especially when each layr was thin. A technique to make individual layrs thin and their surface flat must be developed.Since tempertature where high draw-ratio can be achieved differs between iPP and PE,it was problem to choose an appropriate temperature to draw them highly at the same time. From the present results, it was found that both polymers were smoothly drawn at the same time in the temperature range of 130ﾟC-140ﾟC.Selection and control of an appropriate drawing temperature are the second problem to be solved.Another issue to be overcome is to draw highly the stacked gel-film thus prepared. This is closely related to the above two issues.