Alternating Polymer Laminate for Flexible Barrier Packaging
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Solution Overview
Problem
Current packaging materials face challenges in achieving high barrier properties against gases, aromas, and moisture while maintaining flexibility, toughness, and transparency, often requiring thick barrier layers that can be brittle and costly, and are not environmentally friendly.
Innovation Solution
A laminate structure with alternating layers of thermoplastic polymer blends, incorporating thermoplastic elastomers, is created using a one-step blown film extrusion process with water quenching and controlled blow-up ratio, resulting in a thin, flexible, and tough film with enhanced barrier properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thick barrier layers are used to achieve high barrier properties against gases, aromas, and moisture, then barrier performance is improved, but flexibility and toughness deteriorate
Solution Approach 1:
The barrier layer is segmented into multiple thin alternating layers of different polymers (e.g., PA and EVOH) with thicknesses of 1-20 μm each. This segmentation provides high barrier performance through the cumulative effect of multiple interfaces while maintaining flexibility because each individual thin layer remains ductile and can deform without cracking.
Solution Approach 2:
The invention uses composite material structures combining different polymers (PA/EVOH/PA or PA/PVDC/PA) in alternating thin layers. Each polymer contributes its specific barrier properties against different substances (oxygen, moisture, aromas), and the composite structure achieves superior overall barrier performance while the thin-layer architecture prevents brittleness.
2Strength
If barrier layer thickness is reduced to improve flexibility, then flexibility is improved, but barrier performance deteriorates
Solution Approach 1:
Instead of using a single thick barrier layer, the invention segments the barrier function into multiple thin alternating layers (1-20 μm each). The cumulative barrier effect of multiple layers compensates for the reduced thickness of individual layers, maintaining high barrier performance while ensuring each thin layer remains flexible and ductile.
Solution Approach 2:
The invention transitions from a single-dimensional thickness approach to a multi-dimensional layered architecture. By creating alternating layers of different polymers in the thickness direction, the structure achieves barrier performance through the combined effect of multiple interfaces and material properties rather than relying solely on increased thickness of a single layer.
3Reliability
If inorganic fillers are incorporated to improve gas barrier properties, then barrier performance is improved, but processing complexity and cost increase
Solution Approach 1:
The invention replaces expensive and complex inorganic filler incorporation processes with a more economical approach using organic polymer layers. The alternating polymer layers (PA/EVOH or PA/PVDC) provide gas barrier properties through their inherent molecular structure and interface effects, eliminating the need for costly inorganic fillers and complex secondary coating processes.
Solution Approach 2:
The invention changes the approach from adding inorganic fillers to modifying the polymer layer composition and structure. By selecting specific polymers (EVOH for oxygen barrier, PVDC for moisture and aroma barrier) and controlling layer thickness and sequence, the gas barrier properties are achieved through parametric optimization of organic materials rather than inorganic additive incorporation.
4Reliability
If inorganic coating is applied to improve barrier properties, then barrier performance is improved, but manufacturing complexity increases due to secondary processes
Solution Approach 1:
The invention merges the barrier function into the primary extrusion process by using alternating layers of barrier polymers (EVOH, PVDC) integrated with the structural polymer layers. This eliminates the need for separate secondary coating processes, as the barrier functionality is built-in during the single-step co-extrusion of the multi-layer structure.
Solution Approach 2:
The alternating polymer layers serve multiple functions simultaneously: PA layers provide structural integrity and moisture barrier, while EVOH layers provide oxygen barrier and PVDC layers provide aroma and moisture barrier. This multi-functionality is achieved in a single integrated structure without requiring separate coating processes for different barrier types.
Data Source
AI summary
Laminate structure comprising an alternating stack of layers from polymer blends AC and BD having the sequence -AC-[BD-AC-]n with n from 4 to 36, wherein the layer thickness of layers AC and layers BD is less than 3 μm, wherein A and B are thermoplastic polymers and C and D are thermoplastic elastomers, wherein the thermoplastic polymer B has functional barrier properties, wherein the amount of the thermoplastic elastomers C and D in the polymer blends AC and BD is each from 3 to 45 wt.-%, and polymer B and elastomer D are essentially incompatible.