| 摘要 |
PROBLEM TO BE SOLVED: To provide a packaging bag whose opening is surely hermetically sealed with ease and production is easy. SOLUTION: Flexible two sheets (one is referred to 11a, the other 11b) are superimposed to form a bag main body 1 having a closable opening at one end. Three cores (first core 2A, second core 2B, third core 2C), each of which is formed of a bandlike plate strip, are provided parallel with each other on the external surface of the one sheet 11a defining the opening, such that the first core 2A is situated along an edge of the opening 11 and a first groove 3A of a predetermine length and a second groove 3B of a predetermined length are defined between the cores. The width a of the first core 2A, which is the nearest to the opening 11, is greater than the widths b of the other cores. The sheets 11a and 11b are bent in such a manner that the cores are superimposed along the first groove serving as a fold line. Thus, the opening 11 is hermetically sealed.
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