| 摘要 |
PROBLEM TO BE SOLVED: To form a gored bag out of sheets, each having one surface to which heat bond is not effective, by means of heat-bonding. SOLUTION: The bag 1 is formed by superposing a front side sheet 2a and a back side sheet 2b on each other, whose respective inner faces are thermally weldable, and has a gore 11 whose bottom or both side edges orthogonal to the bottom are folded inside. The joints between the front side sheet 2a and the back side sheet 2b are heat-bonded. In this bag 1, even in the range of notches 4, 4 provided at opposed positions of double portions located inside a quadruply superposed portion of the sheets at the corners where the side edges and the bottom edges cross one another, the thermally weldable faces of the front side sheet 2a and the back side sheet 2b are heat-bonded to each other.
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