Methods for making flexible containers and associated products
Disclosed is a method for making a flexible container. The method implements an injection mold having a collapsible core that expands/moves to define the apertures and, in some embodiments, holds a flexible film in place during the injection mold process and collapses/moves back post-injection molding to allow for the flexible container to be readily removed from the die. In addition, the method described includes a post-injection molding anneal process that is implemented to allow the flexible film to shrink so as to provide for form-fitting of the film to the molded portion of the container.
1. A method for making a flexible container, the method comprising:
providing an injection mold comprising a male die and a corresponding female die;
inserting the male die into the female die, wherein the insertion defines a space between the male die and the female die;
moving a movable portion of the male die to thereby reduce a volume of the space;
injecting a container material in the space and curing the container material to create a molded part having at least one aperture;
moving the movable portion of the male die to thereby increase the volume of the space;
withdrawing the male die from the female die;
removing the molded part from the injection mold;
adhering at least one film to the molded part along a perimeter of the at least one aperture; and
annealing the container at a predetermined temperature and for a predetermined dwell time to thereby shrink the film to form-fit the container.
2. The method of claim 1 , wherein adhering the film further comprises disposing the film in the female die prior to inserting the male die into the female die and wherein curing the container material additionally provides for adhering the film to the molded part over the at least one aperture.
3. The method of claim 2 , wherein moving the movable portion of the male die further comprises moving the movable portion of the male die to thereby hold the film in place.
4. The method of claim 2 , wherein adhering the film further comprises providing for the film comprising a layered laminate of polypropylene, wherein a back layer of the film comprises a temperature-sensitive polymer that adheres to the container material during the curing of the container material.
5. The method of claim 1 , wherein adhering the film further comprises providing for the film to have a predetermined axial grain orientation to thereby affect shrinkage in a desired axial direction during annealing.
6. The method of claim 5 , wherein providing for the film to have the predetermined axial gain orientation further comprises predetermining the grain orientation based on at least one of (1) a type of film used, and (2) a geometry of the container or the at least one aperture.
7. The method of claim 1 , wherein injecting a container material in the space further comprises injecting the container material in the space, wherein the container material is one of polypropylene or polyethylene.
8. The method of claim 1 , wherein curing the container material further comprises curing the container material at a predetermined temperature in a range of 300 to 525 degrees Fahrenheit.
9. The method of claim 1 , wherein moving the movable portion of the male die further comprises closing the injection mold to affect mechanical movement of the movable portion of the male die.
10. The method of claim 1 , wherein moving the movable portion of the male die further comprises opening the injection mold to affect mechanical movement of the movable portion of the male die.
11. The method of claim 1 , wherein annealing the container at a predetermined temperature and for a predetermined dwell time further comprises selecting the predetermined temperature and the predetermined dwell time based on at least one of (1) a size of the container, and (2) a thickness of the film.
12. The method of claim 1 , wherein injecting the container material in the space to create a container having at least one aperture, further comprises injecting the container material in the space to create a container having two apertures, a first aperture opening in a first side portion and a bottom portion of the container and a second aperture opening in a second side portion and the bottom portion, wherein the first side portion is opposite the second side portion.
13. A method for making a flexible container, the method comprising:
providing an injection mold comprising a male die and a corresponding female die;
disposing a film in the female die;
inserting the male die into the female die, wherein the insertion defines a space between the male die and the female die;
moving a movable portion of the male die to thereby reduce a volume of the space and hold the film in place;
injecting a container material in the space to create a container having at least one aperture;
curing the container material, wherein curing the container material provides for adhering the film to the container material over the at least one aperture;
moving the movable portion of the male die to thereby increase the volume of the space;
withdrawing the male die from the female die;
removing the container from the male die; and
annealing the container at a predetermined temperature and for a predetermined dwell time to thereby shrink the film to form-fit the container.
14. The method of claim 13 , wherein disposing the film in the female die further comprises providing for the film to have a predetermined axial grain orientation when disposed in the female die to thereby affect shrinkage in a desired axial direction during annealing.
15. The method of claim 14 , wherein providing for the film to have the predetermined axial gain orientation further comprises predetermining the grain orientation based on at least one of (1) a type of film used, and (2) a geometry of the container or the at least one aperture.
16. The method of claim 13 , wherein disposing the film in the female die further comprises providing for the film comprising a layered laminate of polypropylene, wherein a back layer of the film comprises a temperature-sensitive polymer that adheres to the container material during the curing of the container material.
17. The method of claim 13 , wherein injecting a container material in the space further comprises injecting the container material in the space, wherein the container material is one of polypropylene or polyethylene.
18. The method of claim 13 , wherein curing the container material further comprises curing the container material at a predetermined temperature in a range of 300 to 525 degrees Fahrenheit.
19. The method of claim 13 , wherein moving the movable portion of the male die further comprises closing the injection mold to affect mechanical movement of the movable portion of the male die.
20. The method of claim 19 , wherein moving the movable portion of the male die further comprises opening the injection mold to affect mechanical movement of the movable portion of the male die.
21. The method of claim 13 , wherein annealing the container at a predetermined temperature and for a predetermined dwell time further comprises selecting the predetermined temperature and the predetermined dwell time based on at least one of (1) a size of the container, and (2) a thickness of the film.
22. The method of claim 13 , wherein injecting the container material in the space to create a container having at least one aperture, further comprises injecting the container material in the space to create a container having two apertures, a first aperture opening in both a first side portion and a bottom portion of the container and a second aperture opening in both a second side portion and the bottom portion of the container, wherein the first side portion is opposite the second side portion.
23. A method for making a molded part, the method comprising:
providing an injection mold comprising a male die and a corresponding female die;
inserting the male die into the female die, wherein the insertion defines a space between the male die and the female die;
moving a movable portion of the male die to thereby reduce a volume of the space;
injecting a container material in the space and curing the container material to create a molded part having at least one aperture, wherein moving the movable of the male die defines the at least one aperture;
moving the movable portion of the male die to thereby increase the volume of the space;
withdrawing the male die from the female die; and
removing the molded part from the injection mold, wherein moving the movable portion of the male die assists in removing the molded part from the injection mold.