Hydrogen Generating Closure for Oxygen Scavenging in PET Containers
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Solution Overview
Problem
Polymers used in food and beverage containers, such as PET, are permeable to oxygen, which degrades sensitive products, and existing oxygen scavenging technologies suffer from slow reaction rates, limited capacity, and issues like haze formation and discoloration, especially in transparent packaging and when recycling is considered.
Innovation Solution
Incorporating a hydrogen generating means into the container that slowly releases molecular hydrogen over an extended period, reacting with oxygen in the presence of a catalyst to provide long-term protection, with the rate of release tailored to match oxygen ingress and initiated upon filling, using active substances like sodium borohydride dispersed in a polymeric matrix to control hydrogen generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional oxygen scavengers (iron, sodium bisulfite, oxidizable polymers) are incorporated into the container, then oxygen can be removed from the container interior, but the reaction rate is slow and the scavenging capacity is limited
Solution Approach 1:
The patent changes the chemical parameters by using hydrogen peroxide decomposition instead of traditional oxidation reactions. This enables rapid oxygen generation through catalytic decomposition, achieving both high reaction rate and sufficient scavenging capacity while avoiding the limitations of slow traditional scavenger reactions
Solution Approach 2:
The patent introduces hydrogen peroxide as an intermediary substance that decomposes to generate oxygen. This intermediary approach allows controlled, rapid oxygen generation that can quickly replace lost hydrogen, solving both the speed and capacity limitations of traditional scavengers
2Reliability
If molecular hydrogen is introduced at sealing to scavenge oxygen, then initial oxygen removal is achieved, but hydrogen is quickly lost through permeable plastic walls and protection is only short-term
Solution Approach 1:
The patent incorporates hydrogen peroxide and catalyst in advance within the container structure. This preliminary preparation enables automatic, rapid hydrogen generation when needed, providing sustained protection rather than relying on pre-introduced hydrogen that quickly permeates away
Solution Approach 2:
The patent creates a self-regenerating system where hydrogen peroxide continuously decomposes to replenish hydrogen levels. This self-service mechanism maintains protective hydrogen concentrations over extended periods without external intervention, overcoming the limitation of finite pre-introduced hydrogen
3Illumination intensity
If transparent plastic packaging (PET) is used for product visibility, then consumer appeal is enhanced, but oxygen permeation through the wall degrades the product over time
Solution Approach 1:
The patent implements a self-regenerating hydrogen system that continuously counteracts oxygen permeation. This active defense mechanism allows the use of permeable transparent plastics without sacrificing product protection, as the system automatically replenishes hydrogen to maintain protective levels despite ongoing permeation
Solution Approach 2:
The patent changes the chemical environment within the container by maintaining a hydrogen-rich atmosphere through continuous generation. This parameter change (hydrogen concentration) compensates for the physical property (permeability) of the transparent plastic, enabling both visibility and protection
4Reliability
If oxygen scavengers are incorporated into the container wall or contents, then oxygen can be scavenged, but haze formation and discoloration occur in the packaging material
Solution Approach 1:
The patent extracts the problematic scavenging function from the packaging material itself and relocates it to a separate, contained system (hydrogen peroxide reservoir with catalyst). This separation prevents the scavenging reaction from causing haze or discoloration in the transparent plastic while still achieving effective oxygen removal
Solution Approach 2:
The patent uses hydrogen peroxide decomposition as an intermediary process that generates hydrogen without the side effects of traditional scavengers. This intermediary reaction pathway achieves oxygen scavenging effectiveness while avoiding the haze and discoloration problems associated with iron oxidation, sodium bisulfite, and oxidizable polymers
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
This approach provides sustained protection against oxygen ingress, extending the shelf-life of oxygen-sensitive products by effectively scavenging oxygen over months or years without adulterating the contents, suitable for both rigid and flexible containers and transparent packaging.
Implementation Method 1
hydrogen generating means for generating molecular hydrogen in a chemical reaction involving an active substance which is incorporated in said container
Implementation Method 2
the container also includes a catalyst for catalyzing a reaction between said molecular hydrogen and molecular oxygen
Implementation Method 3
molecular hydrogen will react with any oxygen present in the interior of the container or in the container wall
Data Source
AI summary
A container 22 includes a shell 24 made from a polymer, for example PET, and incorporating a catalyst, for example a palladium catalyst. A closure 40 incorporates a plug which includes a source of hydrogen, for example a hydride. In use, with container 22 including a beverage and closure 40 in position, the headspace in the container will be saturated with water vapor. This vapor contacts the hydride associated with plug 42 and as a result the hydride produces molecular hydrogen which migrates into the polymer matrix of shell 24 and combines with oxygen which may have entered the container through its permeable walls. A reaction between the hydrogen and oxygen takes place, catalyzed by the catalyst, and water is produced. Thus, oxygen which may ingress the container is scavenged and the contents of the container are protected from oxidation.