| 摘要 |
PURPOSE:To obtain a drawn product of syndiotactic polypropylene with excellent transparency by drawing a molded item of polypropylene with syndiotactic structure and treating it with a gaseous hydrocarbon compd. CONSTITUTION:A polypropylene with syndiotactic structure, if necessary mixed with a stabilizer such an antioxidant as is used in the case of molding of isotactic polypropylene, is molded and then drawn. As a molded item to be drawn, a product with a relatively low degree of crystallinity is pref. as it is easily drawable and it is drawable at a high draw ratio. For example, a product with a relatively small strength of a diffraction line observed at a face distance of about 7.1 Angstrom is pref. used. A molded item satisfying this condition exhibits a larger cooling speed after heat melt molding. As the heating temp., a temp. which is 10 deg.C or lower than the m.p. of polypropylene used is pref. The drawn product as it is and under loaded condition is heated with a gaseous hydrocarbon compd. to make the lowered transparency better. |
