Its called mounting adhesive film....
We use it a good bit for second surface prints on acrylic which look amazing when done. There are several brands of it with different qualities like permanent/removable and permanent/permanent adhesive, optically clear with some UV protection, etc. We mostly use Mactac Colortrans but we have also used a Seal branded one as well. Depending on the use we might print on a poster paper for a short term or cheaper product but if frequent cleaning is expected (the edges on paper will absorb moisture) then a wet strength paper or a synthetic material is in order.