ES370792A1 - Plastics bags manufacture - Google Patents

Abstract

A plough or gusset opener comprising a wire 8 and a part 6 of diamond cross-section (Fig. 2) is provided to separate opposed seals e.g. 5a, 5b that may have inadvertantly become sealed together e.g. 5c during their formation e.g. when forming block-bottomed bags. As shown, a folded plastics web 1 having a pleat 2 coated with a yeat-seal inhibitor on its outer surface e.g. printing ink passes to a first heat-sealing station where double V-shaped seals 5, e.g. an example of such a seal being 5a, 5d, are formed to extend partly across the pleat 2 to leave a small separation adjacent the pleat fold 9 wherein the wire 8 may lie. As the web 1 moves intermittently towards a second station providing transverse seals 13, the part 6 progressively separates the opposed arms e.g. 5a, 5b of the V-shaped seals, e.g. 5a, 5d. The wire 8 which is anchored to a support 10, passes through tubing (7, Fig. 2) brazed into a groove along the inner edge of the part 6 to be anchored to a support 11 via a tension adjustor 12. The web 1 may comprise side-gussetted, lay-flat tubing which may be cut longitudinally to form two rows of bag or transversely midway between the transverse seals 13 to form half-sized bags. The bags may be only partly severed from each other. The web may comprise films of polythene, polypropylene copolymers of ethylene or propylene with other olefines or unsaturated monomers, polyethylene terephthalate or vinylidene chloride copolymers. The film may bear a heat-seal coating on its inner surface and be used for packaging cut loaves.