Patent ID: 6986729

Claim:
A method for manufacturing a zippered bag comprising the steps of: folding a sheet of film to provide first and second opposing face members, said first and second opposing face members having a bottom edge, first and second opposing side edges and opposing top edges; folding upper portions of said first and second opposing face members outward along reference lines, which respectively extend on said first and second opposing face members in parallel with said opposing top edges so as to be apart therefrom by a prescribed distance, to provide first and second folded portions with their inner surfaces exposed; heat-sealing said first and second opposing side edges together except said first and second folded portions; subjecting said first and second folded portions to an injection molding to form a male track on the inner surface exposed of one of said first and second folded portions and a female track on the inner surface exposed of an other of said first and second folded portions, said male track and said female track being placed along straight lines, which extend from respective side edges of said first and second folded portions to respective top edges thereof, said male track and said female track being engageable with each other to constitute a zipper; unfolding said first and second folded portions to bring the opposing side edges of the one of said first and second folded portions into contact with the opposing side edges of the other thereof to convert said first and second folded portions into first and second unfolded portions unfolded portions and engage said male track with said female track to keeping said zipper in a closed state so as to be oblique relative to said opposing top edges, thus providing upper and lower engaging points of the zipper; heat-sealing the opposing side edges of one of said first and second unfolded portions to the opposing side edges of an other thereof, respectively, to form a first upper-side heat-sealed portion including said lower engaging point and a second upperside heatsealed portion; and heat-sealing the top edges of said first and second unfolded portions together in a region from said upper engaging point to an upper end of said first upper-side heat-sealed portion, thus forming a nonsealed opening portion in a region from said upper engaging point to un upper end of said second upperside heatsealed portion.