EVOH/EAA Blend Barrier Coatings for Oxygen Transmission Reduction
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Solution Overview
Problem
Current gas barrier coatings for polymeric films, such as PVDC and EVOH, face limitations in achieving high gas barrier properties while being environmentally friendly and cost-effective, as they require thick layers, are moisture-sensitive, or compromise recyclability and transparency.
Innovation Solution
A thin ethylene vinyl alcohol copolymer/ethylene acrylic acid copolymer blend (EVOH/EAA) barrier coating is applied, which reduces oxygen transmission rate by 80% or more and maintains water resistance, allowing for thinner packaging and easier recycling, without the need for thick layers or hazardous materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PVDC is used as a gas barrier coating to achieve high gas barrier properties, then the oxygen permeability is reduced, but the coating thickness must be greater than one micron which increases manufacturing time and facility footprint
Solution Approach 1:
The patent changes the chemical composition parameters of the barrier coating from PVDC to a blend of EVOH and EAA copolymers. This parameter change allows achieving high gas barrier properties with a thinner coating layer, thereby reducing the drying time and facility footprint while maintaining or improving barrier performance.
Solution Approach 2:
The patent uses a composite material system consisting of EVOH and EAA copolymers in specific ratios (30-70 wt% EVOH, 70-30 wt% EAA). This composite approach combines the oxygen barrier properties of EVOH with the moisture resistance and processability of EAA, achieving superior overall performance compared to pure PVDC coatings.
2Reliability
If PVDC is used as a gas barrier coating, then the gas barrier properties are improved, but poisonous dioxin can be generated when burning films which causes environmental and worker safety concerns
Solution Approach 1:
The patent eliminates the harmful byproduct generation entirely by replacing PVDC with EVOH/EAA copolymer blend. The new material system does not generate dioxin when incinerated, converting a harmful process into a safe one while maintaining the desired gas barrier function. This represents a fundamental material substitution that removes the harmful factor rather than managing it.
3Reliability
If EVOH is used as a gas barrier coating to achieve low oxygen permeability, then the oxygen barrier properties are improved, but the coating becomes moisture sensitive which compromises barrier properties at higher humidity
Solution Approach 1:
The patent creates a composite coating system where EVOH (providing oxygen barrier) is blended with EAA copolymer (providing moisture resistance). The synergistic interaction between these two polymers in specific ratios maintains stable barrier properties across varying humidity conditions, eliminating the moisture sensitivity issue of pure EVOH coatings.
4Reliability
If EVOH is used as a gas barrier coating, then the oxygen barrier properties are improved, but the coating shrinks when exposed to higher temperatures which compromises package integrity
Solution Approach 1:
The patent uses a composite of EVOH and EAA copolymers where the EAA component provides thermal stability and reduces shrinkage tendency. The blended system maintains dimensional stability at elevated temperatures while preserving the oxygen barrier properties of EVOH, solving the thermal shrinkage problem through material composition optimization.
5Reliability
If vacuum applied metal or metal oxide coating is used to reduce permeability to light, water, and oxygen, then the barrier properties are improved, but the coating is costly, opaque, and easily damaged reducing recyclability
Solution Approach 1:
The patent replaces expensive vacuum-deposited metal coatings with a cost-effective organic polymer coating system (EVOH/EAA blend). This polymer coating can be applied using conventional coating techniques rather than expensive vacuum deposition equipment, significantly reducing manufacturing costs while providing comparable or superior barrier properties.
Solution Approach 2:
The patent changes the material phase from inorganic metal/metal oxide to organic polymer materials. This parameter change enables the use of solution-based coating methods instead of vacuum deposition, reducing equipment costs and allowing for transparent, recyclable coatings that maintain excellent barrier properties.
Data Source
AI summary
A coated film with barrier properties can include a film comprising a layer selected from the group consisting of a polymer layer, vacuum applied coating, a printed layer, and a primer coating; an ethylene vinyl alcohol copolymer/ethylene acrylic acid copolymer blend (EVOH/EAA) barrier coating on the layer and comprising ethylene vinyl alcohol copolymer (EVOH) and ethylene acrylic acid copolymer (EAA) at a weight ratio of EVOH to EAA of 1.5:1 to about 6:1, wherein the EAA has an acrylic acid content of 10 wt % to 35 wt %; and wherein the coated film has percent reduction in oxygen transmission rate (23° C., 50% relative humidity) of 80% or greater relative to a same film without the EVOH/EAA barrier coating.