WO2000035304A1 - Catalytic process - Google Patents

Catalytic process Download PDF

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Publication number
WO2000035304A1
WO2000035304A1 PCT/GB1999/004100 GB9904100W WO0035304A1 WO 2000035304 A1 WO2000035304 A1 WO 2000035304A1 GB 9904100 W GB9904100 W GB 9904100W WO 0035304 A1 WO0035304 A1 WO 0035304A1
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WO
WIPO (PCT)
Prior art keywords
oxygen
package
catalyst
scavenging composition
oxygen scavenging
Prior art date
Application number
PCT/GB1999/004100
Other languages
French (fr)
Inventor
Amanda Maria Elsome
John Malcolm Gascoyne
Hugh Gavin Hamilton
Allin Sidney Pratt
Raj Rao Rajaram
Elizabeth Slade
Original Assignee
Johnson Matthey Public Limited Company
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Johnson Matthey Public Limited Company filed Critical Johnson Matthey Public Limited Company
Priority to AU15771/00A priority Critical patent/AU1577100A/en
Publication of WO2000035304A1 publication Critical patent/WO2000035304A1/en

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
    • B65D81/00—Containers, packaging elements, or packages, for contents presenting particular transport or storage problems, or adapted to be used for non-packaging purposes after removal of contents
    • B65D81/24—Adaptations for preventing deterioration or decay of contents; Applications to the container or packaging material of food preservatives, fungicides, pesticides or animal repellants
    • B65D81/26—Adaptations for preventing deterioration or decay of contents; Applications to the container or packaging material of food preservatives, fungicides, pesticides or animal repellants with provision for draining away, or absorbing, or removing by ventilation, fluids, e.g. exuded by contents; Applications of corrosion inhibitors or desiccators
    • B65D81/266—Adaptations for preventing deterioration or decay of contents; Applications to the container or packaging material of food preservatives, fungicides, pesticides or animal repellants with provision for draining away, or absorbing, or removing by ventilation, fluids, e.g. exuded by contents; Applications of corrosion inhibitors or desiccators for absorbing gases, e.g. oxygen absorbers or desiccants
    • A—HUMAN NECESSITIES
    • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
    • A23L—FOODS, FOODSTUFFS, OR NON-ALCOHOLIC BEVERAGES, NOT COVERED BY SUBCLASSES A21D OR A23B-A23J; THEIR PREPARATION OR TREATMENT, e.g. COOKING, MODIFICATION OF NUTRITIVE QUALITIES, PHYSICAL TREATMENT; PRESERVATION OF FOODS OR FOODSTUFFS, IN GENERAL
    • A23L3/00—Preservation of foods or foodstuffs, in general, e.g. pasteurising, sterilising, specially adapted for foods or foodstuffs
    • A23L3/34—Preservation of foods or foodstuffs, in general, e.g. pasteurising, sterilising, specially adapted for foods or foodstuffs by treatment with chemicals
    • A23L3/3409—Preservation of foods or foodstuffs, in general, e.g. pasteurising, sterilising, specially adapted for foods or foodstuffs by treatment with chemicals in the form of gases, e.g. fumigation; Compositions or apparatus therefor
    • A23L3/3418—Preservation of foods or foodstuffs, in general, e.g. pasteurising, sterilising, specially adapted for foods or foodstuffs by treatment with chemicals in the form of gases, e.g. fumigation; Compositions or apparatus therefor in a controlled atmosphere, e.g. partial vacuum, comprising only CO2, N2, O2 or H2O
    • A23L3/3427—Preservation of foods or foodstuffs, in general, e.g. pasteurising, sterilising, specially adapted for foods or foodstuffs by treatment with chemicals in the form of gases, e.g. fumigation; Compositions or apparatus therefor in a controlled atmosphere, e.g. partial vacuum, comprising only CO2, N2, O2 or H2O in which an absorbent is placed or used
    • A—HUMAN NECESSITIES
    • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
    • A23L—FOODS, FOODSTUFFS, OR NON-ALCOHOLIC BEVERAGES, NOT COVERED BY SUBCLASSES A21D OR A23B-A23J; THEIR PREPARATION OR TREATMENT, e.g. COOKING, MODIFICATION OF NUTRITIVE QUALITIES, PHYSICAL TREATMENT; PRESERVATION OF FOODS OR FOODSTUFFS, IN GENERAL
    • A23L3/00—Preservation of foods or foodstuffs, in general, e.g. pasteurising, sterilising, specially adapted for foods or foodstuffs
    • A23L3/34—Preservation of foods or foodstuffs, in general, e.g. pasteurising, sterilising, specially adapted for foods or foodstuffs by treatment with chemicals
    • A23L3/3409—Preservation of foods or foodstuffs, in general, e.g. pasteurising, sterilising, specially adapted for foods or foodstuffs by treatment with chemicals in the form of gases, e.g. fumigation; Compositions or apparatus therefor
    • A23L3/3418—Preservation of foods or foodstuffs, in general, e.g. pasteurising, sterilising, specially adapted for foods or foodstuffs by treatment with chemicals in the form of gases, e.g. fumigation; Compositions or apparatus therefor in a controlled atmosphere, e.g. partial vacuum, comprising only CO2, N2, O2 or H2O
    • A23L3/3427—Preservation of foods or foodstuffs, in general, e.g. pasteurising, sterilising, specially adapted for foods or foodstuffs by treatment with chemicals in the form of gases, e.g. fumigation; Compositions or apparatus therefor in a controlled atmosphere, e.g. partial vacuum, comprising only CO2, N2, O2 or H2O in which an absorbent is placed or used
    • A23L3/3436—Oxygen absorbent

Definitions

  • This invention relates to a method of removing small quantities of entrained oxygen from closed containers, sealed bags and the like (hereinafter called “sealed packages”) which contain oxidisable products, including perishable foodstuff, by utilisation of catalytic oxygen scavenging composition.
  • oxidisable product includes materials which are damaged by oxygen or spoiled by micro-organisations in the presence of oxygen.
  • the small quantities of entrained oxygen can be eliminated by including hydrogen in the sealed package to react with the entrained oxygen to produce water.
  • a quantity of hydrogen equal to or greater than that stoichiometrically required to combine with the entrained oxygen is introduced into the package along with an inert gas or gases either before or after sealing.
  • Such foodstuff preservation methods utilise catalysts which have high activity for combining hydrogen and oxygen to produce water.
  • Suitable catalysts include platinum group metals which conveniently can be impregnated on a finely divided inert porous support material. Such supported catalysts are commonly contained in sealed pouches or sachets of microporous film which are stuck on to the interior surface of the packaging material. Sealed pouches or sachets, however, suffer from the disadvantage that the sachet is liable to ruption with the catalyst getting onto the foodstuff.
  • An object of the present invention is to provide an improved oxygen scavenging system which obviates or mitigates the problems experienced with systems containing moisture and carbon dioxide.
  • a method of removing entrained oxygen in a sealed package containing an oxidisable product comprising (1) applying to a predetermined area of the intended inside surface of the package an oxygen scavenging composition comprising a mixture of a hydrophobic material and a catalyst which has a high activity for combining hydrogen and oxygen and (2) introducing into the package before or after sealing hydrogen and an inert gas or gases including carbon dioxide; the hydrogen being present in the package in sufficient amount to react with the entrained oxygen to form water.
  • the catalyst comprises a platinum group metal or combinations thereof.
  • the catalyst may be in the form of a finely divided unsupported material or it may be supported on a porous inert carrier.
  • the porous inert carrier is carbon, alumina, zirconia, silica, ceria, titania or an insoluble carbonate.
  • the hydrophobic material is a fluorocarbon polymer.
  • the fluorocarbon polymer is polytetrafluoroethylene, fluorinated ethylene-propylene copolymer, polychlorofiuoroethylene, polyvinylidene fluoride or mixtures thereof.
  • the oxygen scavenging composition contains a water-insoluble adhesive material.
  • the adhesive material is poly(vinylbutyral), nitrocellulose, ethyl cellulose, a polyurethane or a silicone material.
  • the oxygen scavenging composition contains one or more additives commonly used in ink compositions (including UV curable inks) such as one or more of plasticisers, fillers, driers, surfactants and pigments.
  • additives commonly used in ink compositions such as one or more of plasticisers, fillers, driers, surfactants and pigments.
  • the catalyst particles are partially encapsulated on the surface of the oxygen scavenging composition.
  • the oxygen scavenging composition comprises a minor weight amount of the hydrophobic material and a major weight amount of the catalyst.
  • the oxygen scavenging composition is applied to the intended inside surface of the package by printing, brushing, spraying or powder coating.
  • the oxygen scavenging composition comprises a label which is attached to the intended inside surface of the package.
  • the method of the present invention is particularly suitable for the preservation of perishable foodstuffs, especially moist perishable foodstuffs.
  • the present invention is a sealed package containing an oxidisable product from which package oxygen has been removed by the methods specified above.
  • the present invention is the use as an oxygen scavenger of a catalytic/hydrophobic composition as specified above.
  • the hydrophobic polymeric particles and catalyst particles may be blended by any convenient technique that will produce a uniform mixture.
  • an aqueous suspension may be formed by conventional techniques, such as high shear mixing of a mixture of catalyst particles and an aqueous dispersion of hydrophobic polymer particles.
  • the aqueous suspension is then caused to aggregate (floe), such as by heating or adding a floccing agent.
  • aggregate such as by heating or adding a floccing agent.
  • Alternative methods of obtaining the blend of catalyst particles and hydrophobic polymer particles are disclosed in US Patents Nos. 4,185,131; 4,382,875; 4,851,377 and 4,927,514, the disclosures of which are incorporated herein by reference.
  • the sealed packages holding the oxygen scavenging composition and the perishable foodstuff or other oxidisable product may be in the form of plastic bags, metal cans, glass jars and the like or they may be made of plastic film materials, aluminium foil or combinations thereof as well as of paper or cardboard types of materials which in turn may be coated or impregnated with wax or plastic to provide generally air impervious and waterproof materials.
  • the oxygen scavenging composition of the present invention can be applied in a distributed manner on the interior surface of the packaging material thus providing an extended surface area of contact for the entrained oxygen and the hydrogen within the sealed package.
  • Such an extended area of contact is more difficult to achieve with pouches or sachets containing the catalyst due to restricted gas access to the catalyst.
  • the oxygen scavenger can be face down to the packaging material.
  • the oxygen scavengers of the invention can be used in other applications where small quantities of entrained oxygen can have a detrimental effect on oxidisable products.
  • the present invention can be applied usefully to the storage of chemicals, pharmaceuticals, clothes, skins, medical equipment, instruments, electronic components, artefacts, security packages (eg bank notes) and other oxidisable products.
  • the activity of the scavengers tested in the following Examples is expressed as the time (T 50 ) taken for the oxygen content of the test gas to be reduced by 50%.
  • Rh black flocced with 15wt% PTFE (Fluon GP1, Whitford Plastics Ltd) was dispersed in 39ml of a 1% polyurethane solution (lg polyurethane (Estane 5202F, B.F. Goodrich) made up to 1 OOg with methyl ethyl ketone/ethyl acetate (9: 1 )).
  • the suspension was subjected to high shear mixing for a period of 20 minutes. It was then sprayed on to 150 ⁇ m polyurethane film (Tuftane TFL-1EA, Lord Corporation) marked out with insulation tape into 2cm by 2cm squares and then left to air dry.
  • One label was removed from the sheet and tested for oxygen scavenging ability. This had a T 50 of 20 minutes and furthermore reduced the oxygen level to 0.08% in 180 minutes.
  • a further ink composition containing Pd black at an equivalent metal loading to the inks described in Examples 1 & 2 above was prepared.
  • Pd black was flocced with 9wt% PTFE and 0.53g of the catalyst was mixed with 39ml of 1% polyurethane solution (as described in Example 1).
  • the suspension was sprayed on to polyurethane sheet marked out into 2 x 2 cm squares and left to air dry. One of these labels was removed from the sheet and found to have a T 50 of 235 minutes.
  • An ink was prepared using 1.94g Pt:Ru black (50:50) flocced with 10wt% PTFE dispersed in 39ml of 1 % polyurethane solution (described in Example 1 ). The suspension was high shear mixed and subsequently sprayed on to a polyurethane sheet template of 2 x 2 cm squares, then left to air dry. One of the labels was tested and gave a T 50 value of 40 minutes and reduced the oxygen concentration in the test bag to 0.2% in 150 minutes.
  • a further ink was made using the Pt:Ru black catalyst (as detailed in Example 5), flocced with 20wt% PTFE. 1.94g of this catalyst was dispersed in 2% polyurethane solution (lg of polyurethane made up to 50g with methyl ethyl ketone/ethyl acetate (9:1)) and high shear mixed. The ink was sprayed on to a polyurethane sheet template of 2cm by 2cm squares and the labels left to air dry. One label was selected for testing and reduced the oxygen concentration to 0.52% after 270 minutes.

Abstract

A method of removing entrained oxygen in a sealed package containing an oxidisable product comprising (1) applying to a predetermined area of the intended inside surface of the package an oxygen scavenging composition comprising a mixture of a hydrophobic material and a catalyst which has a high activity for combining hydrogen and oxygen and (2) introducing into the package before or after sealing hydrogen and an inert gas or gases including carbon dioxide; the hydrogen being present in the package in sufficient amount to react with the entrained oxygen to form water. The catalyst comprises a platinum group metal or combinations thereof. The hydrophobic material is polytetrafluorethylene, fluorinated ethylene-propylene copolymer, polychlorofluoroethylene, polyvinylidene fluoride or mixtures thereof. The oxygen scavenging composition may contain a water-insoluble adhesive which may be poly(vinylbutyral), nitrocellulose, ethyl cellulose, a polyurethane or a silicone material.

Description

CATALYTIC PROCESS
This invention relates to a method of removing small quantities of entrained oxygen from closed containers, sealed bags and the like (hereinafter called "sealed packages") which contain oxidisable products, including perishable foodstuff, by utilisation of catalytic oxygen scavenging composition.
In this patent specification the term oxidisable product includes materials which are damaged by oxygen or spoiled by micro-organisations in the presence of oxygen.
It is well known that the deterioration of foodstuff due to oxidation and/or microbial spoilage can be reduced by storing the foostuff under anaerobic conditions. One means of achieving this is to place the foodstuff in a sealed package filled with an inert gas or gases such as nitrogen and/or carbon dioxide. It is very difficult, however, to completely exclude oxygen from the interior of the package with the result that this technique only serves to slow down the rate of deterioration of the foodstuff. If, however, the residual entrained oxygen, and also oxygen exuded by the foodstuff itself with time, in the sealed package can be removed or converted within the package after sealing, a substantially longer life is achieved for the foodstuff.
In a packaging system as described above, the small quantities of entrained oxygen can be eliminated by including hydrogen in the sealed package to react with the entrained oxygen to produce water. A quantity of hydrogen equal to or greater than that stoichiometrically required to combine with the entrained oxygen is introduced into the package along with an inert gas or gases either before or after sealing. Such foodstuff preservation methods utilise catalysts which have high activity for combining hydrogen and oxygen to produce water.
There are many catalysts which can be used in such oxygen scavenging applications.
Suitable catalysts include platinum group metals which conveniently can be impregnated on a finely divided inert porous support material. Such supported catalysts are commonly contained in sealed pouches or sachets of microporous film which are stuck on to the interior surface of the packaging material. Sealed pouches or sachets, however, suffer from the disadvantage that the sachet is liable to ruption with the catalyst getting onto the foodstuff.
We have found that a superior oxygen scavenging system can be obtained by admixing or impregnating a water-insoluble adhesive material with the catalyst in a particular manner and fixing the thus obtained composite on to the intended inside surface of the packaging material. Such an oxygen scavenger system is described in our co-pending application PCT/GB98/02189 which is incorporated herein by reference.
Whilst our above described oxygen scavenging system is a considerable improvement over the systems described in the prior art, we have found that there is a tendency towards earlier deterioration of catalytic activity in systems where a moist perishable foodstuff, e.g. cooked meat, is packaged in an atmosphere containing carbon dioxide.
An object of the present invention is to provide an improved oxygen scavenging system which obviates or mitigates the problems experienced with systems containing moisture and carbon dioxide.
According to the present invention there is provided a method of removing entrained oxygen in a sealed package containing an oxidisable product comprising (1) applying to a predetermined area of the intended inside surface of the package an oxygen scavenging composition comprising a mixture of a hydrophobic material and a catalyst which has a high activity for combining hydrogen and oxygen and (2) introducing into the package before or after sealing hydrogen and an inert gas or gases including carbon dioxide; the hydrogen being present in the package in sufficient amount to react with the entrained oxygen to form water.
Preferably, the catalyst comprises a platinum group metal or combinations thereof.
The catalyst may be in the form of a finely divided unsupported material or it may be supported on a porous inert carrier. Suitably, the porous inert carrier is carbon, alumina, zirconia, silica, ceria, titania or an insoluble carbonate.
Preferably the hydrophobic material is a fluorocarbon polymer. Conveniently, the fluorocarbon polymer is polytetrafluoroethylene, fluorinated ethylene-propylene copolymer, polychlorofiuoroethylene, polyvinylidene fluoride or mixtures thereof.
Preferably, the oxygen scavenging composition contains a water-insoluble adhesive material. Conveniently, the adhesive material is poly(vinylbutyral), nitrocellulose, ethyl cellulose, a polyurethane or a silicone material.
Suitably, the oxygen scavenging composition contains one or more additives commonly used in ink compositions (including UV curable inks) such as one or more of plasticisers, fillers, driers, surfactants and pigments..
Preferably, the catalyst particles are partially encapsulated on the surface of the oxygen scavenging composition.
Further preferably, the oxygen scavenging composition comprises a minor weight amount of the hydrophobic material and a major weight amount of the catalyst.
In one embodiment of the invention, the oxygen scavenging composition is applied to the intended inside surface of the package by printing, brushing, spraying or powder coating.
In another embodiment of the invention the oxygen scavenging composition comprises a label which is attached to the intended inside surface of the package.
The method of the present invention is particularly suitable for the preservation of perishable foodstuffs, especially moist perishable foodstuffs. From another aspect, the present invention is a sealed package containing an oxidisable product from which package oxygen has been removed by the methods specified above.
From yet another aspect, the present invention is the use as an oxygen scavenger of a catalytic/hydrophobic composition as specified above.
It is believed, although we do not wish to be limited to any expression of theory, that the inclusion of a hydrophobic polymer in the oxygen scavenging composition reduces the build up of water within the structure of the catalyst thus allowing continued access to the metal surface for the reactant gases and as such prevents the progressive reduction in catalyst activity with systems not containing hydrophobic polymers.
The hydrophobic polymeric particles and catalyst particles may be blended by any convenient technique that will produce a uniform mixture. For example, an aqueous suspension may be formed by conventional techniques, such as high shear mixing of a mixture of catalyst particles and an aqueous dispersion of hydrophobic polymer particles. The aqueous suspension is then caused to aggregate (floe), such as by heating or adding a floccing agent. Alternative methods of obtaining the blend of catalyst particles and hydrophobic polymer particles are disclosed in US Patents Nos. 4,185,131; 4,382,875; 4,851,377 and 4,927,514, the disclosures of which are incorporated herein by reference.
The sealed packages holding the oxygen scavenging composition and the perishable foodstuff or other oxidisable product may be in the form of plastic bags, metal cans, glass jars and the like or they may be made of plastic film materials, aluminium foil or combinations thereof as well as of paper or cardboard types of materials which in turn may be coated or impregnated with wax or plastic to provide generally air impervious and waterproof materials.
From a practical aspect, the oxygen scavenging composition of the present invention can be applied in a distributed manner on the interior surface of the packaging material thus providing an extended surface area of contact for the entrained oxygen and the hydrogen within the sealed package. Such an extended area of contact is more difficult to achieve with pouches or sachets containing the catalyst due to restricted gas access to the catalyst. From an economical aspect, it is an advantage to have a simple system whereby the catalyst, the hydrophobic polymer and adhesive can be printed, brushed, sprayed or powder coated onto the interior of the surface of the packaging material or attached as a precoated label to the interior surface of the packaging material. In the case of porous labels the oxygen scavenger can be face down to the packaging material.
Although the present invention has been described mainly with reference to the preservation of perishable foodstuff, the oxygen scavengers of the invention can be used in other applications where small quantities of entrained oxygen can have a detrimental effect on oxidisable products. For example, the present invention can be applied usefully to the storage of chemicals, pharmaceuticals, clothes, skins, medical equipment, instruments, electronic components, artefacts, security packages (eg bank notes) and other oxidisable products.
The following examples serve to illustrate certain embodiments and aspects of the present invention but are not intended to imply any limitation of the scope of the invention.
In order to check the oxygen scavenging compositions for catalytic activity, a test procedure was developed which utilised apparatus to determine a change in oxygen concentration versus time. Ham or damp tissues were put into a Tedlar gas bag (maximum volume 1dm3) to provide a moist atmosphere before adding typically 300cm3 carbon dioxide
9cm3 hydrogen (i.e. 3%) and 2.4cm3 oxygen (i.e. 0.8%).
Notes
1. The activity of the scavengers tested in the following Examples is expressed as the time (T50) taken for the oxygen content of the test gas to be reduced by 50%.
2. In each Example, the reduction in oxygen content was measured beyond T50 but each experiment was stopped before total oxygen removal was achieved. EXAMPLE 1
0.8g of Rh black flocced with 15wt% PTFE (Fluon GP1, Whitford Plastics Ltd) was dispersed in 39ml of a 1% polyurethane solution (lg polyurethane (Estane 5202F, B.F. Goodrich) made up to 1 OOg with methyl ethyl ketone/ethyl acetate (9: 1 )). The suspension was subjected to high shear mixing for a period of 20 minutes. It was then sprayed on to 150μm polyurethane film (Tuftane TFL-1EA, Lord Corporation) marked out with insulation tape into 2cm by 2cm squares and then left to air dry. One label was removed from the sheet and tested for oxygen scavenging ability. This had a T50 of 20 minutes and furthermore reduced the oxygen level to 0.08% in 180 minutes.
EXAMPLE 2
An ink comprising 0.96g Pt black flocced with 8wt% PTFE dispersed in 39ml of 1% polyurethane solution (as described in Example 1 ) was high shear mixed for 20 minutes and then sprayed on to 150μm polyurethane film previously marked out with a template of 2cm x 2cm labels. The labels were left to air dry. One label was removed from the sheet and was found to have a T50 value of 45 minutes. Furthermore it reduced the oxygen concentration to 0.167% in 180 minutes.
EXAMPLE 3
A further ink composition containing Pd black at an equivalent metal loading to the inks described in Examples 1 & 2 above was prepared. Pd black was flocced with 9wt% PTFE and 0.53g of the catalyst was mixed with 39ml of 1% polyurethane solution (as described in Example 1). The suspension was sprayed on to polyurethane sheet marked out into 2 x 2 cm squares and left to air dry. One of these labels was removed from the sheet and found to have a T50 of 235 minutes.
EXAMPLE 4
10% Pd supported on carbon (moisture content 57%) was flocced with 30wt% PTFE. 4.29g of this catalyst was mixed with 39ml of 5% polyurethane solution (5g polyurethane made up to 50g with methyl ethyl ketone/ethyl acetate (9:1)). The ink was immediately sprayed on to a 150μm polyurethane sheet template of 2cm x 2cm squares and left to air dry. One of these labels was chosen at random and tested for oxygen scavenging ability. This label had a T5o of 11 minutes and furthermore reduced the oxygen concentration to 0.12% in 105 minutes.
EXAMPLE 5
An ink was prepared using 1.94g Pt:Ru black (50:50) flocced with 10wt% PTFE dispersed in 39ml of 1 % polyurethane solution (described in Example 1 ). The suspension was high shear mixed and subsequently sprayed on to a polyurethane sheet template of 2 x 2 cm squares, then left to air dry. One of the labels was tested and gave a T50 value of 40 minutes and reduced the oxygen concentration in the test bag to 0.2% in 150 minutes.
EXAMPLE 6
A further ink was made using the Pt:Ru black catalyst (as detailed in Example 5), flocced with 20wt% PTFE. 1.94g of this catalyst was dispersed in 2% polyurethane solution (lg of polyurethane made up to 50g with methyl ethyl ketone/ethyl acetate (9:1)) and high shear mixed. The ink was sprayed on to a polyurethane sheet template of 2cm by 2cm squares and the labels left to air dry. One label was selected for testing and reduced the oxygen concentration to 0.52% after 270 minutes.
EXAMPLE 7
lg of 10% Pt on carbon flocced with 30wt% PTFE was mixed with 4.7g of carbon (Ceca) and 15.3g of 2% poly(vinyl butyral) (lg PVB (B79, Monsanto) dissolved in 49g diethylene glycol monoethyl ether) using a triple roll mill. The ink was screen-printed using a 305 counts per inch mesh on to polyurethane sheet to produce a 2 x 2 cm square label. The label gave a T50 of 22 minutes and reduced the oxygen concentration to 0.22% after 45 minutes. EXAMPLE 8
lg of Pt:Ru black (50:50) flocced with 10wt% PTFE was high shear mixed on a triple roll mill with 2g of carbon (Ceca) and lOg terpineol. A small amount of the ink was printed on to polyurethane sheeting and left to air dry. A 2cm x 2cm square was cut from the sheet and this label tested for oxygen scavenging activity. The label gave a T50 value of 115 minutes and reduced the oxygen concentration in the bag to 0.058% after 70 hours.

Claims

1. A method of removing entrained oxygen in a sealed package containing an oxidisable product comprising (1) applying to a predetermined area of the intended inside surface of the package an oxygen scavenging composition comprising a mixture of a hydrophobic material and a catalyst which has a high activity for combining hydrogen and oxygen and (2) introducing into the package before or after sealing hydrogen and an inert gas or gases including carbon dioxide; the hydrogen being present in the package in sufficient amount to react with the entrained oxygen to form water.
2. A method as claimed in claim 1 wherein the catalyst comprises a platinum group metal or combinations thereof.
3. A method as claimed in claim 1 or claim 2 wherein the catalyst is in finely divided unsupported form.
4. A method as claimed in claim 1 or claim 2 wherein the catalyst is supported on a porous inert carrier.
5. A method as claimed in claim 4 wherein the porous inert carrier is carbon, alumina, zirconia, silica, ceria, titania or an insoluble carbonate.
6. A method as claimed in any one of the preceding claims wherein the hydrophobic material is a fluorocarbon polymer.
7. A method as claimed in claim 6 wherein the fluorocarbon polymer is polytetrafluoroethylene, fluorinated ethylene-propylene copolymer, polychlorofluoroethylene, polyvinylidene fluoride or mixtures thereof.
8. A method as claimed in any one of the preceding claims wherein the oxygen scavenging composition contains a water-insoluble adhesive material.
9. A method as claimed in claim 8 wherein the adhesive material is poly(vinylbutyral), nitrocellulose, ethyl cellulose, a polyurethane or a silicone material.
10. A method as claimed in any one of the preceding claims wherein the oxygen scavenger contains one or more additives commonly used in ink compositions.
11. A method as claimed in claim 10 wherein the additive is one or more of plasticisers, fillers, driers, surfactants and pigments.
12. A method as claimed in any one of the preceding claims wherein the catalyst particles are partially encapsulated on the surface of the oxygen scavenging composition.
13. A method as claimed in any one of the preceding claims wherein the oxygen scavenging composition comprises a minor weight amount of the hydrophobic material and a maj or weight amount of the catalyst.
14. A method as claimed in any one of the preceding claims wherein the oxygen scavenging composition is applied to the intended inside surface of the package by printing, brushing, spraying or powder coating.
15. A method as claimed in any one of claims 1 to 13 wherein the oxygen scavenging composition comprises a label which is attached to the intended inside surface of the package.
16. A method as claimed in any one of the preceding claims wherein the oxidisable product is a perishable foodstuff.
17. A method as claimed in claim 16 wherein the oxidisable product is a moist perishable foodstuff.
18. A sealed package containing an oxidisable product from which package oxygen has been removed by the method claimed in any one of claims 1 to 17.
PCT/GB1999/004100 1998-12-11 1999-12-10 Catalytic process WO2000035304A1 (en)

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2007059903A1 (en) * 2005-11-22 2007-05-31 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Composite system, associated use and method for the oxygen-free packaging of items susceptible to oxidation
WO2011112696A3 (en) * 2010-03-12 2011-11-24 Amcor Limited Container having an oxygen scavenging activation system
US9108176B2 (en) 2010-06-25 2015-08-18 Amcor Limited Oxygen scavenging system for a container
US9289938B2 (en) 2010-03-12 2016-03-22 Amcor Limited Container having oxygen scavenging system

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