Tear-off films are used to protect and preserve food before consumption. They are designed to be torn off from the container and become a detached piece of waste.
My idea is to make the film non-detachable from the container, even after the packaging has been opened.
Films are normally sealed on the edges of the container (Image 1). However, if you further seal the film on a "flap" (Image 2), the film will be still partially attached to the container after opening. In order to do so, the film passes through a "chink" in the flap, and it is then sealed on the bottom of it (Image 3). While you remove the film, the part attached to the bottom of the flap will be not torn off, since you would have to apply a force in the opposite direction.
VARIATION WITH PLASTIC LID
It is quite common to find containers having a plastic lid on top of the film, in order to close the container again after the film has been removed (Image 4).
In this case, my idea is to make the film itself take the function of a lid, as you can see in the video. The rigid lid is transformed into a frame, which holds the torn-off film and enables to close it again on the container.
In order to do so, there are the following features:
1) the lid/frame is attached to the container through the flap, which therefore becomes a hinge (the film is still sealed on the flap as described before).
2) The lid is hollow and it has a kind of small "hook" on the top front.
3) The film has a flap, which supports the tear-off operation. Moreover, this flap has a hole in the middle, so it can be "pinned" to the hook and become a single element together with the frame.
Note: the thickness of the film shall be chosen in order to be resistant to the tearing-off operation, as well as to act as a barrier to protect the food.