Claims
- 1. A process for the manufacture of a self-opening polyethylene film bag stack comprising:
- extruding polyethylene polymer comprising high density polyethylene in an amount of at least about 50 wt. % based on the weight of said polymer into a tube and collapsing said tube into a flattened condition;
- corona treating front and back outside surfaces of said tube;
- severing and sealing said tube into individual bag length blanks having sealed ends;
- forming a stack of between about 25 to about 200 of said blanks in substantial registration with each other;
- cutting mouth openings into at least one end of said stack, said mouth openings defining an upper end of said bag stack; and
- applying a predetermined localized pressure to said stack with at least two pressurizing members having pressure application surfaces free of sharp edges to form compressed areas of decreased thickness in an upper region of said stack such that adjacent outer wall corona treated surfaces defined by said compressed area are releasably adhered together and adjacent inside wall surfaces defined by said compressed areas are not adhered together.
- 2. The process of claim 1 wherein said polyethylene polymer comprises high density polyethylene in an amount of at least about 75 wt. % based on the weight of said polyethylene polymer.
- 3. The process of claim 1 additionally comprising the step between said corona treating step and said severing step, of forming longitudinally extending side gussets in said tube.
- 4. The process of claim 1 wherein said step of applying localized pressure to said stack is conducted concurrently with said step of cutting said mouth openings in said stack.
- 5. The process of claim 1 wherein said step of applying localized pressure to said stack is conducted separately from said step of cutting said mouth openings in said stack.
- 6. The process of claim 1 wherein said step of applying localized pressure to said stack comprises contacting said stack with at least two cylindrical shaped pressurizing members having smooth radial shaped pressurizing surfaces.
- 7. The process of claim 1 wherein said step of applying localized pressure to said stack comprises contacting said stack with at least two cylindrical shaped pressurizing members having hemispherically shaped pressurizing surfaces.
- 8. The process of claim 1 wherein said pressurizing members are of a length adapted to compress said stack in an amount of at least about 30%.
- 9. The process of claim 8 wherein said pressurizing members are of a length adapted to compress said stack in an amount of between about 30% and about 50%.
- 10. The process of claim 1 wherein said corona treating step is conducted to provide a surface tension on said outside surfaces of said flattened tube in an amount greater than about 40 dynes/cm.
Parent Case Info
This application is a divisional of application Ser. No. 07/859,037, filed Mar. 27, 1992.
US Referenced Citations (17)
Foreign Referenced Citations (1)
Number |
Date |
Country |
55-6503 |
Feb 1980 |
JPX |
Divisions (1)
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Number |
Date |
Country |
Parent |
859037 |
Mar 1992 |
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