Edge Curling After Lamination? Try Low-temperature Thermal Lamination Film

Lamination should enhance the quality of printed materials, but often results in curling edges that fail to flatten. This not only affects aesthetics but also causes problems for subsequent processes such as die-cutting, hot stamping, and binding. Why does edge curling occur? And how can it be resolved?

Why do edges curl after lamination?

 The root cause of edge curling is the difference in thermal shrinkage rates between the film and the paper.

 
During lamination, heated rollers melt the hot melt adhesive in the thermal lamination film, causing both the film and paper to expand due to heat. During the cooling process after lamination, the shrinkage rate of the film is usually greater than that of the paper. The stress generated by shrinkage pulls the paper edges towards the film side, causing curling.

 
Curling is more likely to occur in the following situations:

• Paper is too thin (e.g., below 120g)
• Paper moisture content is too high
• Laminating temperature is too high (above 100℃)
• Film thermal shrinkage rate is too high
• Small printed material size, resulting in more concentrated stress at the edges

 

How does low-temperature pre-coated film solve the curling problem?

The laminating temperature of ordinary BOPP pre-coated film is usually between 105~115℃. High temperatures exacerbate film shrinkage, increasing the risk of curling. 

Low-temperature pre-coated film lowers the laminating temperature to 85~90℃. Lower temperatures offer three advantages:

• Less thermal expansion of the film, resulting in significantly reduced shrinkage stress upon cooling.
• Reduces paper deformation due to heat.
• Thinner or more sensitive papers can be successfully laminated without curling.

 

Other auxiliary measures: 

Besides using a low-temperature thermal lamination film, you can also:

• Treate the paper to balance its moisture content before lamination.
• Reduce lamination pressure.
• Check the unwinding tension to ensure consistent tension on both sides of the film.
• Flatten the film after lamination and allow it to cool completely before stacking
   

Summary

If you frequently encounter edge curling after lamination, especially with thin paper or high ambient humidity, it is recommended to try a low-temperature pre-coated film (85~90℃). This is often the simplest and most direct solution.

Guangdong EKO Film Manufacture Co., Ltd. Provides high quality low-temperature thermal lamination film. Contact us for sample testing.

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