Flexible packaging is one of the most common packaging methods. the structures of flexible packaging is the usage of laminating adhesive to bond different layers of film, foil, or paper together to form an effective structure to protect the goods within the packaging. The effectiveness of bonding and sealing of the different substrates will involve having the right adhesive mix ratio for film lamination, the right drying temperature and time, the right dyne level of the substrate. Some of the common coating and lamination adhesive issues include:
- Bubbling in lamination:
Substrates can have dust or unwanted particles on their surface which minimize the effectiveness of adhesives. Therefore, we should make sure the substrate surface is clean before substrates laminating. Furthermore, bubbling can be caused by the lack of unwind roll tension before the substrate enters the nip. The insufficient tension will allow air to get trapped between the substrates and form bubbles. Feeding the roll too quickly can also cause bubbles therefore if this is the case, slow down the roll feeding speed into the nip before the lamination happens. Lastly, bubbles can also be caused by low nip pressure or when the nip roller is too soft.
- Ink bleed:
Ink bleed can happen when you start the lamination process before the ink has the chance to be fully dried. Ink bleed can also be caused by ink incompatibility with the adhesive. Not only will ink bleed cause visual defects, but it will also affect the bonding strength of the lamination. The undried ink can form a chemical reaction with the adhesive. The reaction makes a weaker bond between the substrates. Therefore, leave more time for the ink to dry before you start the lamination process. Selecting the right combination of substrate, adhesive, and process is the key to a successful lamination. When defects occur, one or more settings may need to be adjusted to solve these issues. Megabond offers over twenty years of combined experience in PU adhesive and flexible packaging lamination.
