Multilayer Food Packaging with Separable Paper Intermediary
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Solution Overview
Problem
Existing multilayer food packaging materials are not recyclable due to irreversible bonding of layers, making mechanical recycling impossible and leading to thermal recycling, which is environmentally harmful.
Innovation Solution
A multilayer structure comprising a polar oxygen transmission barrier layer, an apolar water vapor barrier layer, and intermediate and outer layers made of paper, which allows for the formation of continuous layers without irreversible bonding, facilitating layer separation for recycling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional petroleum-based and aluminum-based multilayers are used for food packaging, then good barrier properties against oxygen, moisture and light are achieved, but the layers are irreversibly bonded together making mechanical recycling impossible
Solution Approach 1:
The multilayer structure is segmented into distinct functional layers (polar oxygen barrier layer, apolar water vapor barrier layer, intermediate layer, outer layer) that can be separated from each other. The intermediate layer acts as a separable interface that allows mechanical separation of the polar and apolar layers, enabling recycling while maintaining barrier properties through the specific arrangement of functional layers.
Solution Approach 2:
An intermediate layer is introduced between the polar oxygen barrier layer and the apolar water vapor barrier layer. This intermediate layer serves as a mediator that facilitates the bonding of incompatible polar and apolar layers while enabling their subsequent separation during recycling processes, thus resolving the contradiction between achieving good barrier properties and maintaining recyclability.
2Strength
If tie layers are implemented between polar and apolar layers to enhance inter-layer adhesion, then sufficient adhesion is achieved, but the complexity of recycling processes increases and layer separation becomes more difficult
Solution Approach 1:
The intermediate layer is designed with specific local properties that differ from both the polar and apolar layers. It has intermediate polarity and mechanical properties that allow it to bond sufficiently to both incompatible layers during manufacturing, while its distinct characteristics enable easy separation during recycling, thus avoiding the need for complex recycling processes.
Solution Approach 2:
The intermediate layer utilizes changes in physical and chemical parameters (polarity, surface energy, mechanical properties) to achieve different bonding behaviors in different stages. During manufacturing, its parameters allow strong adhesion to both polar and apolar layers; during recycling, these same parameters enable easy separation without requiring complex processing, thus reducing recycling process complexity.
3Object-affected harmful factors
If biodegradable polymers are used to create multilayers, then environmental sustainability is improved, but achieving good oxygen and moisture barrier properties becomes more difficult
Solution Approach 1:
The patent employs composite material construction by combining different biodegradable polymers with specific functional properties in a multilayer structure. The polar oxygen barrier layer uses a biodegradable polymer with low oxygen permeability, while the apolar water vapor barrier layer uses a biodegradable polymer with low water vapor permeability. The intermediate layer combines compatible polymers to ensure bonding, creating a composite structure that achieves excellent barrier properties while maintaining environmental sustainability through biodegradability.
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 provides excellent oxygen and water vapor barrier properties while enabling individual layer separation, thus allowing for conventional recycling and reducing environmental impact.
Implementation Method 1
at least one first layer (1), being polar and functioning as an oxygen transmission barrier
Implementation Method 2
at least one second layer (2), being apolar and functioning as a water vapor and/or humidity barrier
Implementation Method 3
at least one intermediate layer (3), located between a first and a second layer (2), substantially consisting of paper
Data Source
Figure 1~2
AI summary
A multilayer comprises at least one first layer, at least one second layer, at least one intermediary layer and at least one outer layer. The first layer functions as an oxygen transmission barrier and the second layer as water vapor and/or humidity barrier. The intermediate layer is compatible with both, the first and the second layer and makes it possible to form a multilayer from a first layer and a second layer. The outer layer is located on the outside of a first layer and/or of a second layer and is the outside facing layer of the multilayer.