One of the most critical parameters determining quality in flexible packaging production is the long-term preservation of bond strength between layers. Delamination, defined as the separation of film, foil, or paper layers after lamination, poses significant technical and commercial risks for manufacturers.

It not only compromises the physical integrity of the packaging but can also lead to loss of barrier properties, reduced shelf life, and customer complaints.

What Is Delamination?

Delamination occurs when two or more substrates fail to develop sufficient bond strength after lamination or when they separate over time under end-use conditions.

This issue is particularly critical in the following applications:

• Food packaging
• Retort and pasteurization applications
• Medical sterilization packaging
• Industrial packaging requiring chemical resistance

Main Causes of Delamination

1. Surface Tension Problems

In the lamination process, the interaction between the film and the adhesive, as well as the inherent strength of the adhesive’s molecular structure, plays a crucial role. Surface tension is defined as the property that allows a liquid surface to resist external forces due to the cohesive nature of its molecules.

When the adhesive comes into contact with the film, a contact angle is formed. A large contact angle indicates weak attraction between the liquid and solid, whereas a small contact angle indicates strong attraction. As the contact angle increases, the adhesive finds it more difficult to wet the surface, which may result in poor adhesion.

Improving these attraction forces can be achieved by ensuring that lamination films have appropriate corona treatment levels, applying inline corona treatment, or reducing the surface tension of liquids through suitable additives.

2. Incorrect Base Resin/Hardener Mixing Ratio

In two-component polyurethane adhesives, curing occurs through the reaction between isocyanate and polyol groups.

The polyol component contains free hydroxyl (-OH) groups that react with the isocyanate component, which contains free isocyanate (-NCO) groups and forms the main adhesive component.

During this irreversible reaction, chemical bonds form between the -OH and -NCO groups, resulting in a complex polymer structure. To ensure this reaction proceeds properly, optimal adhesive mixing conditions must be maintained. Incorrect mixing ratios are one of the most common causes of delamination.

3. Insufficient Coating Weight

Low coating weight may fail to create an adequate bonding area, particularly in high-barrier structures.

4. Incomplete Adhesive Curing

Depending on the adhesive system used, a specific waiting period is required after lamination before the structure can be further processed. This curing period is essential to prevent delamination.

Even when the adhesive is prepared correctly and applied within the recommended coating weight range, the chemical reactions must be allowed to proceed to completion. The required curing time depends on factors such as:

• The number of layers in the laminate structure
• The solvent composition of the adhesive system
• Environmental conditions such as temperature and humidity

Monitoring and maintaining optimized curing conditions are essential for achieving durable bond strength.

5. Inappropriate Process Parameters

• Lamination nip pressure
• Line speed
• Application temperature
• Ambient humidity
• Viscosity

6. Chemical Effects of the Filled Product

Acidic, oily, or alkaline products can adversely affect adhesive performance over time.

7. Incompatibility Between Ink and Adhesive Systems

Ink and adhesive are two fundamental components of flexible packaging systems. Chemical incompatibility between them is one of the leading causes of delamination.

When developing a packaging structure, the interactions between the chemicals and solvents contained in both the ink and adhesive systems must be carefully evaluated.

The printing ink must be compatible with the substrate and provide strong adhesion. During lamination, the liquid adhesive must not act as a solvent for the cured ink layer, and it must fully cover the printed surface to prevent pinhole formation.

Effects of Delamination on Production

Delamination is not merely a quality issue; it is also an operational risk that directly increases costs.

Major impacts include:

• Product returns and customer complaints
• Increased waste rates
• Line stoppages
• Reproduction costs
• Damage to brand reputation

How to Prevent Delamination Technically

A successful lamination process requires a systematic approach.

Process Control Steps

1. Measuring surface energy
2. Selecting the appropriate adhesive system
3. Verifying mixing ratios
4. Controlling coating weight
5. Optimizing curing conditions
6. Performing peel strength tests
7. Conducting end-use simulations

Why Is Peel Strength Critical?

Peel strength testing quantitatively measures the bond strength between two substrates and is one of the most important indicators of lamination quality.

However, a high peel strength value alone is not sufficient. What truly matters is whether this performance:

• Is maintained over time
• Resists temperature fluctuations
• Remains stable against chemical exposure

Makro Chemical’s Technical Approach

At Makro Chemical, we approach lamination challenges not only from a product perspective but also through a process engineering lens.

In our R&D laboratories, we conduct:

• Peel strength analyses
• Curing performance tests
• Chemical resistance studies
• Application optimizations

These capabilities enable us to develop the most suitable solutions for our customers’ specific production conditions.

Our goal is not merely to bond layers, but to deliver reliable and sustainable performance throughout your production line.

Conclusion

Considering food waste, hygiene requirements, and population growth, demand for flexible packaging continues to increase rapidly. In an industry driven by sustainability and efficient production methods, flawless manufacturing processes are essential to meet this growing demand quickly and reliably.

Delamination remains one of the most significant issues in flexible packaging systems because it can occur during production, filling, packaging, or post-filling stages and may negatively affect the shelf-life properties of the final product.

Permanent solutions can only be achieved by accurately identifying the root cause through a comprehensive evaluation of both raw material interactions and process parameters.

With nearly 30 years of experience and an R&D-driven approach, Makro Chemical provides flexible packaging manufacturers with more than adhesives—we deliver reliable performance.

Makro Chemical The Invisible Strength of Packaging