When seeking foolproof protection, aluminum foil composite film is often the undisputed choice. However, the very properties of this material present extreme challenges to its manufacturing process—loose winding and roll-off have become bottlenecks restricting production efficiency and product quality.
To fundamentally address this issue, we must address the core process. This article will reveal an efficient and reliable solution: optimizing the "glue transfer ratio" to precisely control the glue application amount (within process limits) and simultaneously implementing the "aluminum film inner rewinding" method.
Understanding Aluminum Foil Laminated Film
Aluminum foil laminated film is typically produced using a dry lamination process, combining aluminum foil with films such as BOPP, PET, NY, PE, and CPP. While this multi-material structure offers excellent performance, it also presents significant challenges to the rewinding process due to the varying physical properties of each layer (such as hardness and stretch).
The Root of the Problem: Why is Rewinding So Difficult?
- Understanding the Glue Application and "Hidden" Non-Drying: Many people focus solely on the target glue application amount, overlooking the key to achieving it: the glue transfer ratio. An inappropriate adhesive transfer ratio can cause the actual adhesive amount to deviate from the intended amount. Excessive adhesive not only increases costs but also creates a "lubricating layer" during winding due to excess solvent residue and slow curing, leading to interlayer slippage and a loose core.
- Aluminum foil's rigidity stress: Aluminum foil is stiff and difficult to bend. If used as the outer layer of a winding web, its significant rebound stress can push against the softer inner layer, directly causing web runout or edge stringing.
- Unbalanced tension matching: Each layer responds differently to tension, making a uniform winding tension difficult to meet the requirements of all materials, exacerbating uneven internal stress.
Solution: Dual precision control from "glue" to "winding"
1. Key: Optimizing the "glue transfer ratio" to precisely reduce glue application
- What is the glue transfer ratio?
In an anilox roller coating system, the glue transfer ratio refers to the ratio of the amount of glue transferred to the substrate to the total amount of glue carried by the anilox roller cells. It is influenced by a variety of factors, including adhesive viscosity, solids content, blade pressure and angle, and substrate surface condition.
- How to Operate?
- Diagnosis: When winding is loose, first determine whether the current glue application is too high. Then, systematically examine factors affecting the transfer ratio: Is the adhesive viscosity optimal? Is the scraper worn or applying inappropriate pressure? Is the substrate surface tension within the specified range?
- Optimization: Optimize these parameters to improve the stability and efficiency of the transfer ratio. The goal is to use an anilox roller with the correct mesh size and a stable, high transfer ratio to consistently control the actual glue application at the lower end of the process range (for example, from 3.5 g/m² to 2.8-3.0 g/m²).
- Precise glue control: Avoids glue waste and ensures a uniform adhesive layer thickness.
- Fast curing: A thinner, more uniform adhesive layer means less residual solvent, faster curing, and higher initial tack during winding, fundamentally reducing the risk of interlayer slippage.
- Cost-to-quality win-win: Reduce costs and improve winding quality while maintaining laminate strength.
2. Structural Optimization: Unwaveringly Adopt "Aluminum Film Inner Winding"
- Core Concept: Let material properties serve production, not create obstacles.
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Key Operational Tips: When winding, place the rigid aluminized film or aluminum foil layer as the inner core, and the soft, flexible heat-sealing layer (PE/CPP) on the outside.
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Stress Absorption: The outer heat-sealing layer acts like a sponge, absorbing and cushioning stress generated by the inner aluminum foil.
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Automatic Web Correction: The soft outer layer conforms to and compensates for minor alignment errors, completely eliminating roll deviation.
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Perfect Roll Shape: Achieve perfect rolls with neat edges and a tight structure.
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Practical Summary: When facing the challenges of winding aluminum foil composite films, a systematic solution far outweighs single parameter adjustments.
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First Step: Thoroughly examine and optimize your glue transfer ratio; this is the key to precisely controlling glue application and achieving "dry" winding.
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The decisive step: Changing the winding direction, adopting the golden rule of "aluminum film inside, heat seal layer outside."
By combining precise control of the adhesive with a scientifically designed roll structure, you can not only completely eliminate the problems of loose rolls and roll slippage, but also enter a new era of high-quality production with greater efficiency, stability, and lower costs.