| 摘要 |
<p>A waterproof box or cover blank comprises a flat sheet (1) of non-waterproof corrugated paperboard, which has folding lines (6,7,8,9) and, if desired, incisions (2,3,4,5) for forming corner flaps (16, 17, 18, 19). Blank (1) is on both sides covered by a waterproof plastic film (10, 11), which films are joined by welding outside the external edges of blank (1). Plastic films (10,11) are loosely arranged, i.e. not attached to the flat sheet (1). Plastic films (10,11) are also bonded in slots (2, 3, 4, 5) and split centrally inside them, slots (2, 3, 4, 5) having a width to provide space for welding and slotting tools.</p> |
