Polymer Multilayer with Separable Oxygen and Moisture Barriers
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Solution Overview
Problem
Conventional multilayer packaging materials are not recyclable due to irreversible bonding of layers, leading to environmental issues and thermal degradation of vinyl alcohol-rich polymers during hot-melt processing.
Innovation Solution
A multilayer structure comprising a first layer with a water-soluble polymer and a salt, providing an oxygen transmission barrier, and a second layer with a water vapor and/or humidity barrier, allowing separation and recycling in paper recycling streams, and using bio-degradable materials for environmental compatibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional multilayer packaging materials are used, then barrier performance is achieved, but recyclability is lost due to irreversible bonding of layers
Solution Approach 1:
The packaging structure is divided into separable layers: a water-soluble polymer layer (first layer) that can be detached from the barrier layer (second layer). This segmentation allows the barrier layer to be recycled independently while the water-soluble layer can be disposed of or composted, resolving the contradiction between maintaining barrier performance and enabling recyclability.
Solution Approach 2:
A water-soluble polymer layer acts as an intermediary between the user and the barrier layer. This intermediary layer provides the necessary adhesion and sealing functionality during use, but can be easily removed through water exposure, allowing the barrier layer to be recovered and recycled without contamination.
2Ease of manufacture
If vinyl alcohol-rich polymers are processed by hot-melt, then packaging functionality is achieved, but thermal degradation occurs due to negative difference between crystal melting temperature and degradation temperature
Solution Approach 1:
The patent changes the processing parameters by using water-soluble polymers that can be processed at lower temperatures through aqueous solutions rather than hot-melt processing. This parameter change avoids the thermal degradation issue while maintaining the ability to form functional packaging structures through controlled drying and film formation.
Solution Approach 2:
The patent replaces the thermal processing mechanism (hot-melt extrusion) with an aqueous processing mechanism. The water-soluble polymer is processed in water-based solutions and forms the final structure through evaporation and drying, substituting thermal energy with mass transfer and phase change of water, thereby avoiding polymer degradation.
3Ease of manufacture
If water-soluble polymer is used for recyclability, then separation is enabled, but processing temperature must be kept low to avoid degradation
Solution Approach 1:
The patent changes the processing approach from high-temperature hot-melt to low-temperature aqueous processing. The water-soluble polymer is dissolved in water at ambient or mildly elevated temperatures, allowing layer formation and subsequent easy separation without requiring high temperatures that would cause polymer degradation.
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 achieves high barrier performance for oxygen, water vapor, and humidity while being recyclable and environmentally friendly, suitable for packaging sensitive products like coffee, with layers separable at low temperatures for efficient recycling.
Implementation Method 1
The water-soluble polymer is able to form a solution with water as a solvent. The water-soluble polymer is cold soluble, meaning that the water-soluble polymer is soluble in cold water.
Implementation Method 2
The first layer comprises a salt. The salt can act as a lubricant.
Implementation Method 3
the first layer has an oxygen transmission barrier
Implementation Method 4
The second layer has a water vapor and/or humidity barrier.
Implementation Method 5
vinyl alcohol rich polymers are prone towards thermally induced degradation, this due to the fact, that the difference between their crystal melting temperature and their degradation temperature is often negative
Data Source
AI summary
A multilayer comprises at least one first layer and at least one second layer is provided. The first layer includes a water-soluble polymer, wherein the first layer has an oxygen barrier. Furthermore, the first layer comprises a salt. The salt can act as a lubricant. The second layer has a water vapor and/or humidity barrier. The multilayer can offer a high barrier-performance with respect to oxygen permeation and permeation of water/humidity. This enables for a broad applicability of the multilayer in various areas as e.g., in packing, in particular, for food packing, in particular for packing coffee.