The oxygen absorbing inclusion is in the form of a water impermeable, but water vapour and gas permeable, envelope containing water vapour or hydrogen-activated finely particulate compounds.
The UK-based firm said it could operate in free water without the fill material migrating with the product and is intended to be placed on the inner surface of the primary packaging.
A water impermeable membrane is described as providing a “fully effective barrier to the passage of water, either as a free liquid or as an aqueous solution and its associated dissolved solutes”.
Use in free aqueous liquids
Current oxygen absorbers in the marketplace are effective in removing the oxygen within the head space and that dissolved in the product, maintaining oxygen at low residual levels.
But they are unable to be used in free aqueous liquids as the outer envelope containing the oxygen absorbing material is porous to liquid water, according to the patent.
“The inundation in aqueous liquids, whether it be partial or temporary, of the active oxygen absorbing fill materials in question, will either severely reduce their efficacy or render them entirely ineffective,” said Emco.
Suitable fill materials include as the active component finely comminuted iron metal, ascorbic acid, calcium ascorbate, sodium ascorbate, sodium erythorbate or finely comminuted palladium metal.
All the materials, except palladium metal, require water in order to react with oxygen and remove it from the atmosphere.
The palladium metal acts as a catalyst in the presence of hydrogen, combining it with oxygen and removing oxygen from the headspace in the form of water vapour.
The European patent was filed in June this year and published this month while the UK patent was filed last year.
Material design
Emco said the envelope material is designed to allow the transmission of water vapour, oxygen and hydrogen that enable the fill material formulations to best perform.
In particular embodiments, the liquid water impermeable layer may be a water impermeable layer of polyamide (PA) film, with a thickness of 8μηη - 20μηη, as other polymers are unable to provide the same performance requirements.
The gauge of PA film, deployed in the laminate, is determined by the water vapour transmission rate (WVTR) and oxygen transmission rate (OTR) required by the performance demands of the fill material formulation imposed by the packed product and will vary from products.
EMCO Packaging Systems specialises in active and intelligent packaging, oxygen absorbing technology and the supply of diagnostic equipment including gas analysis and leak detection equipment.