Claims
- 1. A method of making plastic bags in line having reinforced hand holes comprising forming an elongated tube of plastic material with the molecular orientation of the plastic material extending in the longitudinal direction of the tube, forming a longitudinal gusset in the tube to define the upper ends of the bags, said gusset including a pair of foldback reinforcement panels defined between a pair of outer longitudinal fold lines which form the upper ends of the bags and an inner longitudinal fold line which connects inner ends of the foldback reinforcement panels, slitting the inner fold line to open the bags, flattening the tube to form front and back walls of the bags, sealing the longitudinal inner end of each foldback panel to the adjacent wall, while separating the foldback panels to prevent them from being sealed together, punching hand holes in the reinforced upper ends of the bags, forming transverse seals in the longitudinal webs to form side edges of the bags and separating the bags along the transverse seals, the bags having hand holes formed in the reinforced upper ends of the bags in which the molecular orientation of the plastic material extends parallel to the upper ends of the bags.
- 2. A method as set forth in claim 1 in which the separation of the foldback panels is achieved by interposing a cold metal plate between the foldback panels to prevent the panels from being sealed together.
BACKGROUND OF THE INVENTION
This invention relates to a novel method of making in an in-line production stream plastic carry out bags having hand holes reinforced by double ply plastic film in which the molecular orientation of the double ply reinforcing plastic material extends across the bags and generally parallel to the upper ends thereof.
The invention also relates to a plastic carry out bag made by said method.
Plastic bags are widely used by markets and department stores for packaging items purchased by shoppers. To hold down the cost, these shopping bags are generally made of thin film plastic material of suitable mechanical strength having aligned hand holes in the upper regions of the front and rear panels of the bag. The vulnerability of the hand holes to tearing limits the load that the bag can carry.
The hand holes of plastic shopping bags have been reinforced by patches and double ply material, but this adds appreciably to the cost of the bags because it has not been possible to produce such bags in an in-line production stream.
In the in-line production of plastic shopping bags, the shopping bags are generally made from an extruded tube of the plastic material with the lengths of the bags extending longitudinally in the machine direction and the upper ends of the bags extending transversely of the machine direction. Since the molecular orientation of the plastic material extends longitudinally in the machine direction, the hand holes are weak and easily torn and require reinforcement which cannot be achieved in conventional methods of in-line production of bags.
In the novel in-line production of plastic bags according to the present invention, the bags are made with the lengths of the bags extending transversely to the machine direction and the upper ends of the bags extending in the machine direction. In this way, the hand holes in the bags will be stronger and less likely to tear because the molecular orientation of the plastic material will extend across the bag generally parallel to the upper ends of the bags.
In addition, the hand holes are reinforced in the bags by a double ply reinforcement produced in the in-line production stream by forming a gusset in the upper ends of the bags, slitting the inner fold line of the gusset to form foldback reinforcement panels between the front and rear walls of the bags and sealing each foldback reinforcement panel to the adjacent wall of the bag. The hand holes are then punched through the reinforced upper ends of the bags, transverse seals are made in the tube to form the side edges of the bags and the tube is cut along the transverse seals to separate the individual bags.
The bags thus produced in an in-line production stream have hand holes reinforced by double ply plastic material with the molecular orientation of the double ply material extending across the bag and generally parallel to the upper ends of the bags.
As a further feature of the present invention, the bags can be provided with offset upper ends in the in-line process to facilitate opening the bags by forming the inner fold line of the gusset off-center between the fold lines which define the upper ends of the bags.
US Referenced Citations (7)
Foreign Referenced Citations (10)
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Patent Grant
4931033
