Cross-linked EZO Frangible Blend for Vacuum Skin Packaging
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Solution Overview
Problem
Current vacuum skin packaging (VSP) solutions require complex and expensive bottom structures to achieve easy opening, which limits the use of simple and cost-effective support materials, and there are concerns about improper fracture propagation leading to encapsulation when the easy-opening frangible blend is incorporated in the top web.
Innovation Solution
A cross-linked thermoplastic multilayer film is used as a top web in VSP applications, comprising a heat-sealable outer layer, a layer directly adhered to it, and an optional thermoplastic layer, with a cross-linked EZO frangible blend of chemically or physically incompatible polymers, allowing for easy opening without encapsulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the easy-opening frangible blend is incorporated in the top web, then the bottom structure can be simplified, but improper fracture propagation leading to encapsulation may occur
Solution Approach 1:
The patent applies local quality by creating distinct layers with specific functions: the outer heat-sealable layer provides sealing, the intermediate layer contains the frangible blend for controlled fracture, and the inner thermoplastic layer provides structural support. This localized functional distribution enables reliable fracture propagation while simplifying the bottom structure.
Solution Approach 2:
The patent uses composite materials by combining chemically or physically incompatible polymers in the frangible blend layer. This composite structure ensures controlled delamination and fracture propagation through the seal layer when force is applied, preventing encapsulation while maintaining package integrity during normal use.
2Strength
If the top web is cross-linked to improve implosion resistance, then formability and sealing are enhanced, but easy opening performance may deteriorate
Solution Approach 1:
The patent segments the top web into multiple layers with the frangible blend positioned in an intermediate layer. This segmentation allows the cross-linked outer layer to provide implosion resistance while the frangible layer remains capable of controlled fracture for easy opening, resolving the contradiction between strength and ease of operation.
Solution Approach 2:
The patent changes the physical and chemical parameters of different layers: the outer layer is cross-linked to enhance strength and implosion resistance, while the frangible blend layer maintains specific polymer compatibility characteristics that enable controlled delamination. This parameter differentiation allows both high strength and easy opening performance.
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 solution provides reliable and consistent easy opening performance without encapsulation, even when the top web is cross-linked, and reduces manufacturing complexity and costs by simplifying the bottom structure, while maintaining high implosion resistance and formability.
Implementation Method 1
The third system is based on a 'cohesive failure' mechanism. In this latter system, easy opening is achieved by internal rupture of a seal layer or of an adjacent layer that, during opening of the package, breaks along a plane parallel to the layer itself.
Implementation Method 2
a product is placed on the support, that can be flat or shaped, e.g., tray-shaped, bowl-shaped or cup-shaped (called 'bottom' web), and the supported product is then passed to a chamber where a 'top' web is first drawn upward against a heated dome and then draped down, upon and around the product, and against the support, the space between the upper film and the support having been evacuated by differential air pressure.
Data Source
Figure 1a~1b
Figure 2a~2b
Figure 3a~3b
AI summary
The present invention relates to cross-linked vacuum skin packaging (VSP) films used as top webs for VSP packages endowed with easy opening features and to VSP packages obtained therefrom. The films of the invention comprise at least one layer of a frangible blend of incompatible polymers. The easy-to-open VSP packages obtained therefrom may advantageously include very simple and cheap supports.