Heat-seal coatings let paper, board and film be sealed to themselves or to another material without a separate adhesive. Water-based versions avoid solvent emissions and can support recyclable designs.
How they work
The coating is applied and dried on the press. Under heat and pressure in the sealing jaws, it softens, flows into the opposite surface and forms a bond as it cools.
Key properties
- Seal initiation temperature: the lowest temperature that gives a usable seal; lower means faster lines
- Seal strength: measured as force per width; set it for the pack, peelable or permanent
- Hot tack: strength while still hot, important on vertical form-fill-seal machines
- Blocking resistance: the coated reel must not stick in storage
Process tips
Dry fully on the press, control coat weight closely and test seals on the actual packaging line, since dwell time and jaw pressure change results.
