| 摘要 |
The plastic bubble packaging film is manufactured by bonding together two sheets of high density polyethylene (F1, F2) along two sets of joint lines set at right angles to each other and forming a network of sealed envelopes (14) that encapsulate the bubbles. The bond is effected in two successive stages by two pairs of fluted rolls (1a-1b, 7a-7b), one profiled circumferentially, the other axially, between which the sandwiched sheets are caused to pass. The surfaces of the rolls are heated in order to soften the sheets along the joint lines and enable the bond. On passing through the first pair of rolls, lenghtwise seals are effected so as to form tubular envelopes (13) into which air is blown, whereupon the smaller envelopes (14) are sealed off and the bubbles encapsulated by the transverse action of the second pair of rolls. |
