| 摘要 |
PROBLEM TO BE SOLVED: To obtain a case where a gap can be easily formed between the rear sides of sheets that face each other and form the case. SOLUTION: Two sheets 12 face each other with the rear faces inside and gap forming margins 13 are extended from the open edges of the sheets other than the top open edges, and folded back on the rear faces of the sheets. The sheets have only the gas forming margins 13 that are overlaid on the rear faces of the sheets or the gap forming margins 13 and adhesive margins 4 to adhere the sheets together. A gap is formed between the rear faces of the sheets by the gap forming margins 13. |
