| 摘要 |
<p>PURPOSE:To enhance impact resistance, in the cut surface parallel to the circumferential direction of the side wall of a molded container and vertical to the surface of said side wall, by setting the double refractivity shown by the difference between the refractivity in the circumferential direction and the refractivity in a thickness direction to a specific value. CONSTITUTION:In preparing a deep draw molded container from a sheet composed of polyethylene terephthalate by a plug-assist method, the deep draw molded container is obtained by setting the diameter or width of a plug to 80% or less of the inner diameter of a mold and the double refractivity between the refractivity n1 in a circumferential direction and the refractivity n2 in a thickness direction is set at least to 0.05 in this container. Therefore, plug temp. is set to a temp. range from the glass transition temp. Tg of the sheet to Tg+90 deg.C. This deep draw molded container is obtained for the first time by a plug-assist method. In a conventional deep drawing molded container, the side wall of the container is molecularly oriented only in a longitudinal direction. Contrarily, since this container takes a biaxial orientation structure wherein a molecular chain is also oriented in the circumferential direction, no longitudinal cracking is generated and impact resistance is excellent.</p> |
