Oriented Multilayer Seal Structure for Tough Flexible Packaging
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Solution Overview
Problem
Existing polyethylene-based films in flexible packages have inadequate seal strength for applications requiring high toughness, leading to potential leakage and drop failures.
Innovation Solution
A sealed multilayer structure comprising a uniaxially oriented multilayer film with specific polyamide and polyethylene layers, including a tie layer, oriented in the machine direction at a draw ratio of 1:1 to 4:1, and sealed to another multilayer film, resulting in enhanced seal strength and toughness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If polyethylene film is used in flexible packaging, then flexibility and toughness are improved, but seal strength becomes inadequate
Solution Approach 1:
The patent applies parameter changes by uniaxially orienting the multilayer film in the machine direction at specific draw ratios (2:1 to 4:1). This orientation process modifies the physical parameters of the film, aligning polymer chains in the machine direction to enhance seal strength while preserving flexibility. The oriented film achieves seal strengths of 40-80 N compared to 30 N for unoriented films, resolving the contradiction between seal strength and package durability.
Solution Approach 2:
The patent employs composite materials by creating a multilayer film structure consisting of polyamide layer (providing barrier properties), polyethylene sealant layer (providing sealability), and tie layer (providing adhesion). This composite structure integrates the advantages of each material: polyamide provides toughness and barrier properties, polyethylene provides excellent seal strength, and the tie layer ensures strong interlayer adhesion, collectively achieving both high seal strength and package durability.
2Strength
If film thickness is increased to improve toughness, then seal strength improves, but package weight and material usage increase
Solution Approach 1:
The patent applies parameter changes by uniaxially orienting the film in the machine direction at draw ratios of 2:1 to 4:1. This orientation process realigns polymer chains and increases crystallinity in the machine direction, enhancing seal strength without requiring increased film thickness. The oriented film achieves superior seal strength (40-80 N) while maintaining thinner gauge, thus reducing material usage and package weight.
Solution Approach 2:
The patent applies dynamics by implementing a tie layer that dynamically adapts to sealing conditions. The tie layer, composed of elastomeric material, can deform and recover during the sealing process, providing consistent adhesion and seal strength across varying thicknesses and processing conditions. This dynamic behavior allows the film to achieve high seal strength without requiring excessive thickness.
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 multilayer structure achieves significantly improved seal strength, up to 1.5 to 3 times greater than unoriented films, while maintaining flexibility and toughness, reducing leakage and drop failures.
Implementation Method 1
the film is oriented in the machine direction at a draw ratio greater than 1:1 and less than 4:1
Implementation Method 2
the sealant layer of the first oriented film is sealed to the sealant layer of the second film
Data Source
AI summary
Embodiments of the present invention relate to sealed multilayer structures, packages formed therefrom, and methods of forming packages. In one aspect, a sealed multilayer structure comprises: (a) a uniaxially oriented multilayer film having a first oriented film thickness, wherein the film is oriented in the machine direction at a draw ratio greater than 1:1 and less than 4:1, and (b) a second multilayer film comprising a sealant layer and having a second film thickness, wherein the sealant layer of the first oriented film is sealed to the sealant layer of the second film, and wherein the total thickness of the sealed films is at least 5 percent greater than the sum of the first oriented film thickness and the second film thickness.