Method of making a plastic film with integrated zipper closure, and plastic bag having an integrated zipper closure
A method of manipulating thermoplastic film to create integrated features and particularly relates to an improved method of manufacturing a packaging bag that is reclosable after initial opening. Multiple sections of thermoplastic film are layered on top of themselves to form a multi-layer portion of the thermoplastic film. The multi-layer portion may then be conglomerated into a unitary thicker portion of the film that can then be shaped into a closure strip. In order to form a bag, a second such closure strip may be made. The two closure strips are then aligned and the remaining open portions of the bag are then sealed such that the closure strips form a reclosable opening that may be opened and closed repeatedly.
1. A method comprising:
layering multiple first sections of thermoplastic film, wherein said multiple first sections are continuous and integral parts of said film, to form a first multi-layer portion;
using a first heated shaping die to heat and apply pressure to said multiple sections of said first multi-layer portion to transform said first multi-layer portion into a unitary first thicker portion of said film and simultaneously shape the unitary first thicker portion into a first closure strip;
layering multiple second sections of thermoplastic film, wherein said multiple second sections are continuous and integral parts of said film, to form a second multi-layer portion;
using a second heated shaping die to heat and apply pressure to said multiple sections of said second multi-layer portion to transform said second multi-layer portion into a unitary second thicker portion of said film and simultaneously shape the unitary second thicker portion into a second closure strip; and
placing the first and second closure strips in aligned positions allowing the closure strips to be engaged with each other to form a reclosable closure device.
2. The method of claim 1 , wherein the first and second closure strips are integral parts of the same piece of thermoplastic film.
3. The method of claim 2 , comprising folding the piece of thermoplastic film into a C-fold configuration that places the first and second closure strips in aligned positions.
4. The method of claim 3 , further comprising sealing the first and second closure strips together along opposite side edges thereof so as to form a bag.
5. The method of claim 1 , wherein the layering multiple second sections of thermoplastic film comprises folding the film multiple times in alternating opposite directions to form the second multi-layer portion having three or more layers.
6. The method of claim 1 wherein the heated shaping die heats and applies pressure to both sides of said multiple sections of said first multi-layer portion.
7. The method of claim 1 wherein the second heated shaping die heats and applies pressure to both sides of said multiple sections of said second multi-layer portion.
8. The method of claim 1 wherein said first closure strip is shaped by heating said first thicker portion and using vacuum.
9. The method of claim 1 wherein said second closure strip is shaped by heating said second thicker portion and using vacuum.
10. The method of claim 1 , further comprising forming a peel seal adjacent to the reclosable closure device.
11. A reclosable closure device formed via the method of claim 1 .
12. The method of claim 1 , wherein the first and second closure strips are integral parts of two discrete pieces of thermoplastic film.
13. The method of claim 12 , further comprising sealing a bottom edge and opposing side edges of the two discrete pieces of thermoplastic film thereof so as to form a bag.
14. The method of claim 1 , wherein at least one of the multiple first sections and the multiple second sections are disposed adjacent an edge of the thermoplastic film.
15. The method of claim 1 , wherein at least one of the multiple first sections and the multiple second sections are disposed in a location below the top edge of the thermoplastic film.
16. The method of claim 1 , wherein at least one of the multiple first sections and the multiple second sections comprise at least three layers.
17. The method of claim 1 wherein the first closure strip comprises a male element and the second closure strip comprises a female element.