Tear resistant separable end-connected bags
AssigneeUnion Carbide Corporation
InventorsCharles R. Walitalo, Alvin E. Ericson
Life of this patent
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Abstract
Continuous strip closed-bottom open-mouthed packaging bags are produced by continually making, at spaced intervals in a continuous flattened tubular oriented plastic film supply, a transversely extending heat seal to define a bag bottom, and, adjacent each heat seal, perforating the two plies of the film supply with a blade heated to effect annealing of the edges of the perforations and having a serrated cutting edge with spaced deep recesses to define connecting tabs between perforations.
Claims6
A method for making a sheet of flexible oriented plastic film material comprising the steps of:
- (a) forming a continuous strand of separable edge-connected flexible oriented plastic film sheets by
- advancing a continuous length of said material to a sheet perforating station;
- cutting elongate perforations with a heated blade through said material transversely to the direction of its advance;
- forming interperforation tabs, one between each two of and in linear alignment with said elongate perforations, tear-oriented into one sheet of each two said sheets and connecting each sheet to a contiguous sheet in the strand;
- simultaneously with forming said tabs annealing the cut edges of said perforations;
- and
- (b) tear-removing said film sheets from said continuous strand.
A method for making packaging bags of flexible oriented plastic film material comprising the steps of:
- (a) forming a continuous strand of separable end-connected flexible oriented plastic film packaging bags by
- (i) advancing a continuous length of flattened flexible plastic film tubing having opposed walls in contact with each other to a bag forming station;
- (ii) forming, at the bag forming station, a heat seal transversely across the flattened flexible plastic film tubing to seal the opposed walls thereof into a bag bottom;
- (iii) cutting elongate perforations with a heated blade through said tubing to define interperforation tabs of tubing material linearly aligned with the perforations, tear-directed into the tubing material adjacent said bag bottom, said perforations being substantially parallel to said bag bottom forming heat seal, to form a bag mouth joined to the tubing material adjacent said bag bottom by said interperforation tabs;
- (iv) annealing the cut edges of said perforations with said heated blade simultaneously with said cutting;
- (v) repeating the steps (i) and (iv) and
- (b) tear-removing said bags from said continuous strand.
A method for forming a continuous strand of separable end-connected flexible plastic film packaging bags comprising the steps of:
- advancing a preselected length of flattened flexible plastic film tubing having opposed walls in contact with each other to a bag forming station;
- forming a heat seal transversely across the flattened flexible plastic film tubing to seal the opposed walls thereof into a bag bottom;
- cutting elongate perforations through said tubing to define interperforation tabs of tubing material linearly aligned with the perforations, tear-directed into the tubing material adjacent said bag bottom, said perforations being substantially parallel to said heat seal to form a bag mouth joined to the tubing material adjacent said bag bottom by said interperforation tabs;
- and
- simultaneously with forming said tabs annealing the cut edges of said perforations.
Dependencies are inferred from the claim text.