| 摘要 |
<p>PROBLEM TO BE SOLVED: To eliminate a possibility that either a core paper inside a cardboard sheet or adhering part in it is decreased in its strength or peeled off at an early time even under an environment of its use where humidity is high or water leakage occurs and the cardboard sheet can be fully washed with water to enable itself to be washed by several times even under a case in which the cardboard sheet is stained in a cardboard box assembled from a flat-plate cardboard raw material comprised of a cardboard sheet formed into a predetermined developed shape corresponding to an assembled state of the cardboard box and a pair of front and rear water-proof films for use in covering two front and rear surfaces of the cardboard sheet over each of these entire surfaces. SOLUTION: A circumferential edge of a cardboard box raw material BF is provided with a water-proof seal means S for use in sealing a circumferential edge end surface De not covered by water-proof covering films C, C of the cardboard sheet D over these entire circumferences from outside.</p> |
