Adhesive Application
Joining separate flexible webs using a dried adhesive layer allows the creation of multi-layer barrier films with high optical clarity. This converting process, known as dry bond lamination, involves applying a liquid adhesive to one substrate and passing it through a drying oven to evaporate the carrier solvent before combining it with a second substrate. The dried tacky layer is then pressed against the second web in a heated nip to form a strong, immediate bond.
By removing the solvent beforehand, the process prevents solvent entrapment in non-porous webs like polyester and aluminum foil, which would otherwise weaken the structure or cause odors in food packaging.
Process Variable
Temperature and pressure within the laminating nip dictate the final bond strength and optical quality of the multi-layer structure. Operators must maintain the oven temperature high enough to remove all residual solvent while avoiding thermal deformation of thin polymeric films. If the web speed or tension is incorrect, the material can curl or develop optical defects like tunneling and blistering after winding.
Material Compatibility
Material compatibility extends across a wide variety of substrates including paper, aluminum foil, and oriented polypropylene. Since the adhesive is completely dry before the webs meet, the process works well for non-porous barriers that would otherwise trap moisture or solvent. Manufacturers rely on this method to produce high-barrier structures for food packaging that require sterilizing or boiling.
