Analysis of Delamination in Multi-Layer Plastic Films

Challenges and Solutions: 

Analysis of Delamination in Multi-Layer Plastic Films After Solvent-Free Laminating

The use of multi-layer plastic films in packaging applications has gained significant traction due to their superior barrier properties and versatility. However, a common issue that arises in the production of these films, especially after solvent-free laminating, is delamination. This article analyzes the causes of delamination in solvent-free laminated films and presents potential solutions to this challenge.

Delamination refers to the separation of the layers in a laminated film, which can compromise the integrity, performance, and appearance of the packaging. This issue can occur during processing, storage, or even use, leading to product spoilage and increased waste.

Causes of Delamination:

1)Inadequate Adhesion:
One of the primary reasons for delamination is insufficient adhesion between the layers. This can result from improper processing conditions, such as inadequate temperature, pressure, or dwell time during the laminating process.

2)Material Compatibility:
The choice of materials used in the lamination process plays a critical role. If the materials have incompatible surface energies or insufficient bonding characteristics, they may not adhere properly.

3)Environmental Factors:
Factors such as humidity, temperature fluctuations, and exposure to chemicals can weaken the bond between layers. Moisture ingress can particularly be detrimental, leading to hydrolytic degradation of the adhesive.

4)Mechanical Stress:
During handling, transportation, or end-use, mechanical stress can lead to delamination if the film is not robust enough to withstand the forces applied.

Implementing Improved Adhesives ?

Utilizing advanced adhesive formulations designed for solvent-free applications can enhance adhesion. These adhesives often provide better performance under varying environmental conditions.

1. Select the Appropriate Type of Adhesive
Assess Requirements: Choose the appropriate type of adhesive based on the application environment (such as temperature, humidity, and chemical exposure).
Compatibility Testing: Ensure that the selected adhesive is compatible with the materials used (such as PE, PET, CPP, etc.).

2. Optimize the Formulation
Improve Formulation: Use the latest adhesive formulations, adding enhancers (like tackifiers or antioxidants) to improve bonding performance.
Adjust Viscosity: Modify the viscosity of the adhesive to suit the coating process and ensure even application.

3. Adjust Processing Parameters
Temperature and Pressure: Optimize temperature and pressure during coating and curing processes to achieve the best adhesion.
Coating Method: Use an appropriate coating method (such as gravure, spray, or doctor blade) to ensure uniform application of the adhesive.

4. Pre-Treatment
Surface Treatment: Treat the substrate surface (such as corona treatment, plasma treatment, or chemical treatment) to increase surface energy and enhance adhesive bonding.
Clean the Substrate: Ensure the substrate surface is free from dust, oil, or other contaminants to improve adhesive performance.

5. Testing and Evaluation
Adhesion Strength Testing: Regularly conduct adhesion strength tests (such as shear strength, peel strength, etc.) during production to assess the performance of the adhesive.
Environmental Adaptability Testing: Perform durability tests under various environmental conditions to ensure the adhesive performs well in actual usage.

6. Training and Best Practices
Employee Training: Train personnel on the characteristics of the adhesive and its importance in production.
Information Sharing: Establish a feedback mechanism to share issues and improvement suggestions regarding adhesive use.

7. Continuous Improvement
Feedback Mechanism: Create a feedback loop to collect insights from customers and production lines to continuously optimize adhesive performance.
Investment in R&D: Invest in research and development of new materials and technologies to continually seek ways to improve adhesion strength.

How to Choose the Right Type of Adhesive to Meet Specific Needs ?
 

1. Evaluate the Application Environment
Temperature Range: Determine the temperature range of the environment where the product will be used, and select an adhesive that maintains performance within that range.
Humidity Conditions: Consider the performance of the product in humid environments and choose an adhesive with good moisture resistance.
Chemical Exposure: If the packaging material will come into contact with specific chemicals (such as oils, acids, or bases), select an adhesive that has chemical resistance.

2. Determine the Type of Substrate
Material Compatibility: Understand the types of substrates being used (such as PE, PET, CPP, aluminum foil, etc.), and choose an adhesive that has good bonding performance with them.
Surface Treatment: If the substrate has undergone special treatments (such as corona treatment), ensure that the selected adhesive can bond well with the treated surface.

3. Choose the Type of Adhesive
Water-Based Adhesives: Environmentally friendly and low-odor, suitable for food packaging and general applications.
Solvent-Based Adhesives: Provide strong initial bonding strength, suitable for applications requiring quick curing, but be mindful of volatile organic compounds (VOCs).
Hot Melt Adhesives: Melt upon heating and solidify upon cooling, suitable for fast production lines and high-performance applications.
Solvent-Free Adhesives: Ideal for environmentally sensitive applications, usually offering good bonding performance and durability.

4. Consider Adhesion Strength and Curing Time
Initial and Final Adhesion Strength: Determine the required bonding strength and choose an adhesive that provides sufficient adhesion during both initial application and long-term use.
Curing Time: Consider the speed of the production line and select an adhesive with a curing time that matches the production efficiency.

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