| 摘要 |
The non-gusseted, side seamed expansible envelope of the present invention comprises a back panel, front panel and closure flap prepared from a single blank of paper or the like. The side seams are formed from a first pair of flaps foldably attached to the ends of the back panel and a second pair of flaps foldably attached to the ends of the front panel. Each of the side seam flaps are applied with diagonally oriented perforated lines that are located equidistant from the score line separating the front and back panels, and the second pair of side seam flaps are also applied with longitudinally oriented perforated lines which together with the diagonally oriented perforated lines provide the expansion characteristics of the envelope.
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