Recyclable Thermoformable Packaging Film With EVOH Barrier
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Solution Overview
Problem
Current packaging films for food and non-food products, especially those made of PA and PE, are not recyclable due to differences in Tm and Tg, and they lack the necessary mechanical strength and heat resistance for effective protection and thermoforming.
Innovation Solution
A thermoformable and recyclable packaging film with a structure that includes a barrier layer of ethylene vinyl alcohol (EVOH) and compatibilizer layers made of linear low-density polyethylene grafted with maleic anhydride, along with polyolefin-based base and functional layers, ensuring connectivity and enhanced mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If coextruded films made of PA and PE are used to provide barrier properties and heat resistance, then the packaging film achieves necessary protection and mechanical strength, but the films cannot undergo the same recycling cycles due to differences in Tm and Tg and are not considered recyclable
Solution Approach 1:
The invention extracts the EVOH barrier layer from the multi-material coextruded structure and isolates it as a separate functional layer within a predominantly polyolefin-based film. This allows the barrier function to be preserved while the bulk film structure remains compatible with polyolefin recycling processes, enabling the packaging to undergo standard recycling cycles despite containing the high-performance EVOH layer
Solution Approach 2:
The invention creates a composite film structure where a thin EVOH barrier layer (providing oxygen and moisture barrier properties) is integrated within a polyolefin-based matrix. This composite structure combines the benefits of EVOH's barrier performance with polyolefin's recyclability, achieving both protection and environmental sustainability
2Reliability
If a barrier layer with sufficient thickness is used to ensure proper protection, then the packaging achieves necessary barrier properties, but the film structure becomes heterogeneous and unsuitable for deep drawing and thermoforming
Solution Approach 1:
The invention applies the barrier function locally through a thin EVOH layer (at least 1 micron) positioned strategically within the film structure, rather than using thick barrier layers throughout. This localized approach provides sufficient protection for the product while maintaining the overall film's homogeneity and thermoformability, as the thin barrier layer does not significantly interfere with heat and pressure distribution during forming processes
3Reliability
If multiple layers are used to provide barrier and protective functions, then the packaging achieves necessary protection, but the film structure becomes complex and heterogeneous, reducing mechanical strength and creating recycling issues
Solution Approach 1:
The invention maintains film homogeneity by using a polyolefin-based structure for the majority of the film layers, with EVOH confined to a thin intermediate barrier layer. This homogeneous polyolefin matrix ensures consistent mechanical properties, flexibility, and structural integrity, while the thin EVOH layer provides barrier functionality without creating a complex multi-material structure that would compromise strength or recyclability
Data Source
AI summary
A thermoformable packaging film is provided for use in the packaging of food products such as meat and meat products, milk and dairy products, seafood, and bakery products, having an inner layer and an outer layer on the other side facing the food product to be placed in the film layers in which it is formed in the event that it becomes a package, and having a barrier layer in the middle. The packaging film includes a compatibilizer layer positioned between the inner layer and the barrier layer, as well as the outer layer and the barrier layer, to connect the other film layers, and the barrier layer is of ethylene vinyl alcohol material with a weight of at most 5% of the total packaging film weight and a thickness of at least 1 micron, with other layers from a polyolefin-based mono material.