The (possible) patent has some good details (https://patentimages.storage.googleapis.com/a4/8c/8c/934f5a5e98b7b6/EP3613603A1.pdf https://patentimages.storage.go

The (possible) patent has some good details (https://patentimages.storage.googleapis.com/a4/8c/8c/934f5a5e98b7b6/EP3613603A1.pdf https://patentimages.storage.googleapis.com/a4/8c/8c/934f5a5...) > The ink storage pipe includes an at least two-layer structure of an inner layer in contact with ink and a base layer, the base layer being formed of a paper base material and the inner layer being formed of a resin. The resin is preferably an acrylic resin, polystyrene, a fluorine resin, silicone or a mixture thereof. > In case of applying a resin film, the inner layer 4 has a thickness of typically 3 to 90 micrometre and preferably 5 to 60 micrometre. This honestly seems like the coke cans (https://youtu.be/uQHFQoFoxvQ?t=25 https://youtu.be/uQHFQoFoxvQ?t=25). In any case, this should be easier to recycle than the cans.