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Multi-layer Laminate: Material Combinations for Octagonal-Sealed Bags
Release Date:
2026-03-11
Summary
The three-dimensional structure of octagonal stand-up pouches sets them apart from conventional pouch designs in terms of physical form, but their effectiveness in protecting food depends largely on the composition of the materials used. The design approach of multi-layer composite films allows for tailored material combinations based on the specific characteristics of different foods.
The Basic Framework of Composite Structures
The material structure of octagonal-sealed food bags consists of a multi-layer composite of functional films, with each layer serving a distinct purpose. The outer layer typically uses materials such as BOPP, BOPET, or BOPA to provide printability and surface abrasion resistance; The middle layer uses materials such as aluminum foil, metallized film, EVOH, or PVDC-coated film to block oxygen, water vapor, and light; the inner heat-seal layer uses CPP or PE to ensure heat-seal strength and safety for food contact.
This layered design allows the protective performance of the packaging to be adjusted by modifying the material and thickness of the middle layer, rather than relying on the properties of a single material.
Three Common Combination Routes
To meet the preservation requirements of different types of food, the material combinations used in gusseted pouches have evolved into three common configurations:
The first is the plastic-to-plastic composite type, with common structures such as nylon and polyethylene (NY/PE) or polyester and polyethylene (PET/PE). This type of packaging features a transparent or semi-transparent design, allowing the contents to be viewed directly, and is suitable for dry snacks, candies, and other general food products that do not require high-temperature processing.
The second type is the plastic-to-plastic high-temperature retort-resistant composite, featuring structures such as nylon and polypropylene (NY/CPP) or polyester and polypropylene (PET/CPP). This type of packaging can withstand high-temperature retort sterilization and is suitable for food categories requiring sterilization processes, such as ready-to-eat dishes and meat products.
The third type is the aluminum-plastic composite, with structures such as a combination of polyester, aluminum foil, and polyethylene (PET/AL/PE), or a combination of polyester, aluminum foil, and polypropylene (PET/AL/CPP). The addition of the aluminum foil layer significantly enhances oxygen barrier and light-blocking properties, making it suitable for foods with high fat content or those requiring light-protected storage, as well as certain pet foods.
Logic for Matching Materials and Content
When selecting materials, the material combination for octagonal-sealed bags must be tailored to the characteristics of the contents. For foods such as nuts, where fats are prone to oxidation, material combinations with low oxygen transmission rates should be selected; for products like coffee and tea, where aromas are easily lost, the packaging must offer high overall seal integrity and aroma retention; for frozen foods or those requiring high-temperature sterilization, the materials must possess both low-temperature and high-temperature resistance to prevent damage under extreme temperature conditions.
Additionally, the composite film must undergo a curing process prior to bag manufacturing to allow the adhesive molecules to fully cross-link, thereby achieving the desired peel strength. This process ensures the stability of the bond between the layers and is a critical step in preventing delamination or bag rupture during use. The logic behind the material selection for octagonal-seal bags is, at its core, “matching materials to the product”—the packaging structure serves the protection needs of the contents, and the two work together to ensure the safe storage and transportation of the food.
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