Contre-mesures anti-adhérence pour les taches blanches composites en feuille d'aluminium, pénétration difficile de la colle
This issue is common in standard aluminum foil laminations. It occurs because aluminum foil has inherent pinholes, and adhesive curing is a relatively slow process. During curing, the adhesive may seep through the pinholes under the pressure of the wound roll, causing reverse adhesion (back-penetration).
Main Solutions:
Select Aluminum Foil with Fewer Pinholes:
l There is a direct correlation between foil thickness and the number of pinholes—thicker aluminum foil generally has fewer pinholes, making lamination easier.
l It is recommended to choose Grade A aluminum foil with a thickness of 6.5-7μm to minimize pinholes.
Use High-Viscosity Adhesives:
l Choose high-viscosity adhesives like polyurethane retort-grade adhesive or special high-viscosity adhesives for aluminum foil.
l Since aluminum foil lamination typically occurs at speeds of 100-150m/min, higher-viscosity adhesives with larger molecular weight and better leveling properties reduce seepage into pinholes, significantly mitigating reverse adhesion.
Control the Interval Between Laminations:
l When laminating PET/aluminum foil before adding the inner layer, manage the interval properly.
l The recommended intermediate curing time is 2-4 hours to ensure adequate adhesive performance and prevent seepage.
