How to Correctly Use Holographic Films in Food Packaging
In the flexible packaging industry, polyethylene (PE) has become the universal "jack-of-all-trades" for inner layer materials due to its excellent heat-sealing performance and cost advantages. However, the physical and chemical properties of materials dictate that no single film is truly omnipotent. If the characteristics of the product contents do not perfectly match the material, even the most exquisitely designed packaging will face a severe quality crisis during its shelf life.
High-Temperature Retort Pouches Must Not Use PE
When working with clients producing ready-to-eat foods, braised meats, or wet pet food, we frequently hear the question: "Can we just use a standard aluminum-plastic composite structure?"If the food requires sterilization at 121°C or even higher temperatures after filling, using PE as the inner layer is a fatal mistake.
From the perspective of polymer properties, the low-density polyethylene (LDPE) or linear low-density polyethylene (LLDPE) conventionally used for the inner layer of flexible packaging typically has a melting point between 110°C and 130°C. This means that once placed in a high-temperature and high-pressure retort autoclave, the PE layer will soften or even partially melt.
The direct consequence is that the packaging will suffer severe bursting post-sterilization, wrinkling at the seals, or delamination of the once-tight composite layers due to the inner layer's deformation. Therefore, in this specific sector, the inner layer must be replaced with high-temperature-resistant Cast Polypropylene (CPP). A slight misstep in material selection often results in a 100% defect rate during subsequent production line testing.
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High-Volatility Contents Will Penetrate PE
Another easily overlooked scenario occurs when packaging high-fat foods (like certain nuts and heavy-oil sauces) and foods rich in volatile aromatic compounds (like premium spices, specialty coffees, or essential oil food additives).
PE is inherently a non-polar polymer, granting it a natural affinity for equally non-polar oils and organic volatiles. If PE is used directly as the inner layer, the oils and aromatic components in the food will slowly penetrate the PE layer during long-term storage.
This not only alters the product's flavor profile but, more critically, causes the PE layer to swell. This physical alteration drastically weakens the heat-seal strength, causing an otherwise sturdy package to split open easily during transit. For products with extreme demands for aroma retention and oil resistance, we typically recommend introducing co-extruded films containing EVOH or Nylon, or utilizing specific ionomers to replace standard PE, effectively locking in the product's core flavor.
How Lepu Ensures Your Packaging is Perfect
The complexity of materials science lies in the fact that a film exhibiting perfect metrics in a laboratory will often show a completely different "temperament" once it enters the actual lamination, curing, and pouch-making processes. Choosing the wrong inner material will not only ruin a batch of products but also severely damage your brand's market reputation.
At Lepu, we never blindly push standardized, off-the-shelf solutions. We understand that the pH value, oil content, sterilization conditions, and shelf-life requirements of every food product are entirely unique.
Backed by profound expertise in packaging engineering, we conduct rigorous content compatibility analysis at the very beginning to provide you with precise structural customization. Whether you require functional packaging with specialized barrier properties or conventional pouches pursuing maximum cost-effectiveness, Lepu ensures stable processes and reliable quality as your product transitions from R&D prototyping to mass production.
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If you are currently struggling with leaking packages, bursting bags, or a shelf life that falls short of expectations, it might just be your material structure sounding an alarm. Feel free to communicate with us anytime for a professional diagnostic solution.