Methods for making flexible containers and associated products
Presented 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 the form-fitting of the film to the molded portion of the container.
1. A flexible container, the flexible container comprising:
a molded part having at least one aperture, wherein the molded part is formed within an injection mold comprising a male die having a central axis and a corresponding female die, wherein (i) the male die is inserted into the female die to define a space between the male die and the female die, (ii) a moveable portion of the male die is moved away from the central axis to thereby reduce a volume of the space, (iii) a container material is injected in the space, and (iv) the container material is cured to create the molded part; and
at least one film adhered to the molded part along a perimeter of the at least one aperture, wherein the molded part and the at least one film are annealed at a predetermined temperature and for a predetermined dwell time to shrink the at least one film to form-fit the flexible container.
2. The flexible container of claim 1 , wherein, in response to curing the container material, (v) the movable portion of the male die is moved towards the central axis to thereby increase the volume of space, (vi) the male die is withdrawn from the female die, and (vii) the molded part is removed from the injection mold.
3. The flexible container of claim 1 , the least one film is adhered to the molded part by disposing the film in the female die prior to inserting the male die into the female die and wherein the container material is cured to adhere the film to the molded part along the perimeter of the at least one aperture.
4. The flexible container of claim 2 , wherein the movable portion of the male die is moved away from the central axis to thereby further hold the film in place.
5. The flexible container of claim 2 , wherein the at least one film further comprises a layered laminate polypropylene.
6. The flexible container of claim 5 , wherein the layered laminate polypropylene includes a back layer comprising a temperature-sensitive polymer that adheres to the container material during the curing of the container material.
7. The flexible container of claim 1 , the at least one film is configured with a predetermined axial grain orientation to thereby affect shrinkage in a desired axial direction during annealing.
8. The flexible container of claim 7 , wherein the predetermined axial grain orientation is predetermined based on at least one of (1) a film used, and (2) a geometry of the flexible container or the at least one aperture.
9. The flexible container of claim 1 , wherein the container material is one of polypropylene or polyethylene.
10. The flexible container of claim 1 , wherein the container material is cured at a predetermined temperature in a range of 300 to 525 degrees Fahrenheit.
11. The flexible container of claim 1 , wherein the movable portion of the male die is moved away from the central axis by closing the injection mold to affect mechanical movement of the movable portion of the male die away from the central axis.
12. The flexible container of claim 2 , wherein the movable portion of the male die is moved towards the central axis by opening the injection mold to affect mechanical movement of the movable portion of the male die towards the central axis.
13. The flexible container of claim 1 , wherein the molded part and the at least one film are annealed at a predetermined temperature and for a predetermined dwell time, wherein the temperature and the dwell time are selected based on at least one of (1) a size of the container, and (2) a thickness of the film.
14. The flexible container of claim 1 , wherein the molded part includes a first aperture opening in a first side portion and a bottom portion of the flexible 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.