A coating gives paper its own sealing layer. Uncoated paper usually seals to a film that carries the sealant. Coated paper brings the sealant with it, so it can seal directly to trays, films, and blisters.
The coating layout changes how the paper behaves. Grid and pattern coatings cover part of the surface and leave uncoated areas that help the paper stay breathable. An allover coating covers the full surface, which lowers the paper's porosity. If you sterilize with EtO, confirm gas exchange and aeration with an allover-coated web in your cycle.
A good heat-seal coating, sealed within the right window, is designed to separate at the seal instead of tearing the paper, which keeps fiber tear and loose fibers to a minimum when the package is opened. Check the peel on your own tray or film during seal trials.
Typical applications include
- Rigid-tray lidding
- Blister lidding
- Paper-to-film seals