Polypropylene Barrier Lidding Film for Peelable Food Containers
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Solution Overview
Problem
Conventional peelable container lids face issues with strong adhesion, leading to difficulty in removal and potential delamination, while weak adhesion results in premature removal due to incidental causes, and existing films often fail to provide a balanced moisture and gas barrier with desirable adhesive characteristics.
Innovation Solution
A multilayer composite film with a polymeric base layer, an organic thin barrier layer, an ethylene polymer-based adhesive layer, and a heat seal layer, specifically using ethylene vinyl acetate copolymer, which is applied through extrusion coating to ensure a robust yet peelable bond with a balanced adhesive characteristic.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the adhesion of the lidding film to the container is made strong, then the film provides firm bonding and prevents premature removal, but the film becomes difficult to remove and may delaminate leaving residue on the container
Solution Approach 1:
The lidding film is divided into multiple functional layers with distinct properties: a polypropylene base layer for structural integrity, a barrier layer for moisture and oxygen protection, an adhesive layer for controlled bonding, and a heat seal layer for sealing. This segmentation allows each layer to optimize its specific function while working together to achieve both strong adhesion and clean removal.
Solution Approach 2:
The invention uses a composite multilayer structure combining different materials (polypropylene, barrier materials, adhesive polymers, and heat seal materials) to achieve properties that no single material could provide alone. The composite structure enables simultaneous achievement of strong adhesion, barrier protection, and clean peelability.
2Ease of operation
If the adhesion to the container mouth is made weak, then the film can be easily removed, but the film can be removed inadvertently or prematurely by incidental causes such as pressure and movement
Solution Approach 1:
Different regions and layers of the lidding film have different adhesive properties tailored to their specific functions. The adhesive layer is formulated with specific tack and bonding strength to provide reliable attachment under normal conditions while allowing controlled removal. The heat seal layer provides localized strong bonding at the seal perimeter while the center portion maintains peelability.
3Reliability
If a highly effective moisture and/or gas barrier layer is included, then the film provides excellent barrier properties, but the film preparation becomes difficult and adhesive characteristics are compromised
Solution Approach 1:
The barrier function is separated into a dedicated barrier layer with specific thickness and material composition optimized for moisture and oxygen protection. This layer is distinct from the adhesive and heat seal layers, allowing independent optimization of barrier performance without compromising adhesive properties. The segmented structure simplifies the formulation and processing of each individual layer.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The film achieves a durable and complete peel-off without residue, providing excellent moisture and oxygen barrier properties while maintaining structural integrity and ease of removal, suitable for diverse container compositions.
Implementation Method 1
a heat seal layer which is thermally adhered to the circumference of the container mouth, provides a seal removable by peeling
Implementation Method 2
an organic barrier layer that provides excellent moisture and/or oxygen barrier
Data Source
AI summary
Multi-layer films suitable as sealable or peelable sheet that can be used for closing foodstuff containers are described. These multi-layer films includes a polymeric substrate layer and a seal or a peel-seal layer. The multilayer composite film preferably includes four component layers, namely in order, a polymeric base layer for mechanical strength, a thin organic barrier layer, an ethylene polymer-based adhesive layer, and a heat seal layer including an ethylene copolymer, such as ethylene vinyl acetate copolymer. The film is useful as a peelable heat sealable lid for containers of diverse polymer compositions storing various products such as foodstuffs and pharmaceuticals.