Closure Liner Hydrogen Generation for Oxygen Scavenging
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Solution Overview
Problem
Current oxygen scavenging technologies in polymer containers, such as those using oxidizable solid materials, suffer from slow reaction rates, limited capacity, and issues like haze formation and discoloration, particularly in transparent PET packaging, which limits their application and recyclability.
Innovation Solution
A closure system with a hydrogen generating means that includes an active material reacting with moisture to produce molecular hydrogen, which reacts with oxygen in the container, using a polymeric matrix to control the release rate and a catalyst to enhance the scavenging reaction, ensuring minimal impact on the contents and extending shelf-life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If oxygen scavengers utilizing oxidizable solid materials are used, then oxygen scavenging function is achieved, but reaction rate is slow
Solution Approach 1:
The patent changes the chemical form of the active material from solid oxidizable materials to water-soluble metal salts or coordination compounds. This parameter change enables the material to dissolve and react rapidly with oxygen in aqueous environments, dramatically increasing the scavenging rate while maintaining effectiveness through controlled dissolution and catalytic activity.
Solution Approach 2:
The patent replaces the mechanical/solid-state oxidation process with a chemical dissolution and catalytic reaction mechanism. By using water-soluble metal salts that dissolve and form active catalytic species in solution, the system achieves much faster oxygen scavenging kinetics compared to solid material oxidation, effectively substituting a slower physical process with a faster chemical process.
2Productivity
If traditional oxygen scavengers are used, then oxygen is removed, but haze formation and discoloration occur in transparent packaging
Solution Approach 1:
The patent changes the physical and chemical parameters of the active material to water-soluble forms that do not cause haze or discoloration. By selecting metal salts and coordination compounds that fully dissolve and react in aqueous phases, the system achieves oxygen scavenging without the particulate matter or chemical byproducts that cause visual defects in transparent packaging.
Solution Approach 2:
The patent employs water-soluble metal salts that are consumed in the oxygen scavenging reaction, forming soluble byproducts that do not accumulate as visible deposits. These materials are designed to be completely utilized in the scavenging process, leaving no residual solid particles that would cause haze, effectively using consumable materials that disappear after serving their function.
3Reliability
If oxidizable solid materials are incorporated into the package, then oxygen scavenging is achieved, but the packaging material becomes discolored
Solution Approach 1:
The patent substitutes solid material oxidation with aqueous-phase catalytic oxidation using water-soluble metal salts. This replacement eliminates the need for solid oxidizable materials that cause discoloration, as the new system operates in solution and produces soluble byproducts that do not affect the visual appearance of the packaging.
Solution Approach 2:
The patent introduces water as an intermediary medium that dissolves the metal salt active material, enabling the oxygen scavenging reaction to proceed in aqueous solution. This intermediary allows the reaction to occur without solid material contact with the packaging, preventing discoloration while maintaining scavenging effectiveness through the dissolved and catalytically active metal species.
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 system effectively scavenges oxygen over an extended period, maintaining product freshness and safety while minimizing hydrogen presence to prevent container expansion and ensuring compatibility with both rigid and flexible containers.
Implementation Method 1
an active material arranged to generate molecular hydrogen on reaction with moisture
Implementation Method 2
permeable means diffusion of small molecules through a polymeric matrix by migrating past individual polymer chains
Implementation Method 3
a catalyst to enhance the scavenging reaction
Implementation Method 4
reaction between molecular hydrogen and molecular oxygen
Data Source
AI summary
A closure 40 for a container body includes a liner 46 which incorporates a hydrogen generating device comprising a hydride which generates hydrogen on contact with moisture. The liner may be an interference fit within the body 42. The liner 46 and other liners described may include control means for controlling passage of moisture to the hydrogen generating means and/or sealing means for sealing the closure to a container. In use, with the closure secured to a container, water vapor passes into liner 46 and contacts the hydride which generates hydrogen. A reaction between hydrogen and oxygen which has passed into the container takes place, catalysed by a catalyst, and water is produced. Thus, oxygen is scavenged.