| 摘要 |
PURPOSE:To permit the whole slit cutting process to be completely omitted and reduce the manufacturing costs of cushioning sheet by forming the non- fusible parts in the air blowing tubes to be passed through an expandable air bag and self-close valves therein in a simultaneous operation and using the same technique as in the non-fusible parts required for the tube formation. CONSTITUTION:A main area part 13 extending lengthwise along the middle of a tube film 11 consists of a central non-fusible part 14 and non-fusible side parts 15 extending sidewise to the film edges at predetermined intervals. The non-fusion treated tube film 11 is heat sealed to another tube film 12 with thus treated surface facing inward. The films 11 and 12 thus joined together are heat sealed at side edge 18 along the full length thereof with the non-fusible parts 15 left unsealed at intervals at the side edge 17 and these unsealed parts constitute self-close valves 19 and air blowing tubes 10. The air blowing tubes are spliced and inserted between two bag films 2 and 3 for forming the air bags 20 of an expandable cushioning sheet 1. |
