| 摘要 |
PROBLEM TO BE SOLVED: To provide a beautiful packaging container having almost no uneven sections for which the softening temperature has not to be so strictly controlled when a sheet is formed by adopting synthetic resin sheet of constant elastic force and tension in a wide heating temperature zone. SOLUTION: When the synthetic resin sheet 13 is formed of a three-layer structure constituted of a core layer 14 composed of a resin composed of a polyethylene terephthalate as a main component, on both sides of which skin layers 15, 15 constituted of the polyethylene terephthalate are laminated, the IV of respective skin layers 15 is defined as 0.5-1.2 (d1/g), and the IV of the core layers 14 is defined as 70-90% of the IV of the skin layers 15, and the thickness of the core layer 14 is formed thicker than those of the skin layers 15. |
