| 摘要 |
PURPOSE: To obtain a band having high strength and excellent longitudinal crack resistance by specifying the integral strength ratio of scattering strengths in the band lateral and lengthwise directions in the case of measuring the small angle X-ray scattering of a polypropylene band elongated in the lengthwise direction. CONSTITUTION: A banded material of a raw material containing polypropylene melted and extruded from the die 1 of an extruder is cooled to be solidified by a first cooling water tank 2, a banded raw fabric is obtained, then heated by a preheating tank 3, the temperature of the fabric is set to about 70-100 deg.C, and drawn by a first roll 4. At the first stage orientation, it is oriented about six to ten times between first roll 4 and second orientation rolls 5. At the second stage orientation, it is oriented 1.2-3 times between first and second orientation rolls 5 and 7 while heating by a second orientation tank 6. In this case, the integral strength ratio in the case of measuring small angle X-ray scattering becomes 2.0 or more. The orientation temperature of this case is generally below (7.5×orientation magnification + 40) deg.C and preferably (7.5×orientation magnification + 40)-(7.5×orientation magnification) deg.C. |
