| 摘要 |
A flat bottom plastic film bag includes triangular gusset portions formed by a plurality of parallel heat welds which fuse portions of opposed pleats together and cooperate with a transverse central bottom seam to form a flat bottom bag from a seamed or seamless plastic film tube. The longitudinal side and end walls of the bag are provided with heat embossed corrugations which enhance the freestanding characteristics of the bag and a transverse crease is formed along the fold line between the sidewalls of the bag and the bottom wall to enhance the bottom forming characteristics of the bag when it is snapped from a folded position to an opened position. The bag may be made by an improved process wherein a blown film tube is continuously slit sealed into a plurality of tubes which are reinflated, then collapsed to form opposed double pleat folds, followed by corrugation of the side and end walls of the tube, formation of the transverse crease defining the fold line between the bottom and sidewalls and, finally, formation of the gusset welds, the transverse bottom seal and perforation or cutoff to form the individual bags. |
