Re-Pulpable Paperboard Packaging With Soluble Barrier Coating
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Solution Overview
Problem
Existing packaging materials for liquids and frozen foods are difficult to repulp due to the separation issues of plastic coatings from paperboard, and they lack effective moisture and oxygen barriers without using aluminum layers.
Innovation Solution
A packaging material with a water-soluble polymer layer, such as PVOH or starch, directly contacting an extruded polyolefin layer, providing a high moisture and oxygen barrier while facilitating repulpability, and a dispersion barrier layer on the print side for moisture resistance and printability, without additional aluminum or multiple polyolefin layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple polyolefin layers and aluminum foil are used to provide moisture and oxygen barrier, then barrier properties are improved, but repulpability deteriorates due to separation issues of plastic coatings from paperboard
Solution Approach 1:
The invention removes the aluminum foil layer and reduces multiple polyolefin layers to a single layer, extracting the problematic components that hinder repulpability while maintaining barrier functionality through alternative means
Solution Approach 2:
The invention changes the chemical composition parameters of the barrier layer by using water-soluble polymers (PVOH, starch, CMC) instead of traditional polyolefins and aluminum, enabling the barrier to provide protection while being compatible with repulping processes
2Ease of manufacture
If a water-soluble polymer layer is used between paperboard and polyolefin, then repulpability is improved, but barrier properties may be compromised
Solution Approach 1:
The invention creates a composite structure where water-soluble polymer layers are combined with a single polyolefin layer, achieving synergistic effects where the water-soluble polymer enables repulpability while the polyolefin provides enhanced barrier properties
Solution Approach 2:
The water-soluble polymer layer acts as an intermediary between the paperboard substrate and the polyolefin layer, facilitating the separation of polyolefin during repulping while maintaining the integrity and barrier function of the overall structure
3Reliability
If barrier coatings are applied on both inside and outside of fiber based material, then barrier properties are improved, but device complexity increases
Solution Approach 1:
The invention removes the outer barrier coating and aluminum foil layer, simplifying the overall structure while maintaining necessary barrier properties through the optimized combination of water-soluble polymer and single polyolefin layer
Solution Approach 2:
Instead of applying barrier coatings on both sides of the paperboard, the invention applies barrier functionality primarily on the inside surface through the water-soluble polymer and polyolefin combination, inverting the traditional approach of dual-sided coating
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 material achieves high oxygen and moisture barrier properties with reduced repulping rejects, allowing easy recycling and printability, while eliminating the need for aluminum and minimizing polyolefin usage.
Implementation Method 1
Without wishing to be bound to any theory, it is assumed that this might be due to the fact that a trans-crystalline structure may be formed at the interface between the polyolefin layer and the water-soluble polymer layer
Implementation Method 2
As used herein, a water-soluble polymer refers to a polymer that dissolves, disperses, or swells in water
Implementation Method 3
As used herein, a water-soluble polymer refers to a polymer that dissolves, disperses, or swells in water
Data Source
Figure 1~2
AI summary
The invention relates to a packaging material comprising: a paperboard substrate comprising a first and a second side, at least one barrier layer applied on the first side of the substrate, the barrier layer comprising a water-soluble polymer selected from the group of polyvinyl alcohol, a copolymer of ethylene and polyvinyl alcohol, starch, carboxymethylcellulose and combinations thereof in an amount of at least 50 weight%, based on the dry weight of the barrier layer, an extrusion coated layer of a polyolefin on the barrier layer, and at least one dispersion barrier layer applied on the second side of the substrate, which at least one dispersion barrier layer forms a printing surface of the packaging material. The invention further relates to a method of manufacturing a respective packaging material.