Abstract: A high impact strength, flexible bag comprises a bag formed from spaced confronting walls of flexible sheet material joined together at the margins thereof to form a sealed enclosed space only partially filled with a liquid which is to be dispensed from the bag. There is immersed in the body of the liquid within the bag an open-cellular compressible body which extends throughout most of the liquid in the bag when the bag is lying on a horizontal support surface. The structure defining the open cells of the compressible body form such a substantial obstruction to the outward flow of liquid in the bag when a sudden external force is applied to the bag that the liquid therein cannot flow outward to rupture the bag walls.

Abstract: A unique preferably Y-shaped tear line-forming perforation is formed in the sealed marginal portion of a flat bag made of confronting panels of synthetic plastic material sealed together at marginal portions thereof. The perforation is formed with a unique bag-puncturing tool having a faceted, tapered tool head having preferably only three straight longitudinally extending bag-cutting edges converging to a bag-puncturing point at the end of the tool head.

Abstract: A roll of flattened tubular synthetic plastic stock is unwound by the pulling force of clamping devices mounted on a vertically movable frame and engaging the opposite faces of still flattened portions of the tubular stock. The unwound flattened tubular stock is preferably advanced downwardly between bag slitting, wall separating and bag sealing devices also carried by the framework. A lower pair of clamping members forms a temporary seal along the entire width of the tubular stock at a point adjacent to but above the bottom margin of a bag-forming portion thereof until a permanent seal is formed beneath the same and above another pair of lower clamping members which engage the upper margin of a previously filled bag-forming portion of the same. A lower slitting device slits the bag between the latter pairs of clamping members while the clamping members are in operative position.