Liquid purification or separation – Processes – Chemical treatment
Patent
1995-07-13
1999-09-28
Anthony, Joseph D.
Liquid purification or separation
Processes
Chemical treatment
210750, 25218828, 2521881, 25218823, 25218825, 252397, 426107, 4284111, C02F 170, C09K 1500, C01B 302, B01D 1904
Patent
active
059582545
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to compositions for reducing the oxygen concentration present in an atmosphere or liquid (often referred to as oxygen scavenging). In one particular application, the compositions are used in or in association with food packaging.
BACKGROUND OF THE INVENTION
A wide variety of foods and other materials are susceptible to loss in quality during storage under atmospheric levels of oxygen. The damage can arise from chemical oxidation of the product, from microbial growth, and from attack by vermin--much of which may be avoided by reducing the oxygen availability in the environment of the materials. In the field of packaging, relatively low-oxygen atmospheres have traditionally been generated by vacuum packing and inert gas flushing. Such methods are not, however, generally applicable for various reasons. For example: thorough inert gas flushing of food packages; occlusion of air; which may have desorbed from the food or entered the package by leakage or permeation.
As a consequence there has been much interest in chemical techniques for generating low-oxygen atmospheres and deoxygenating liquid or semi-liquid foods. Thus, there are approaches based on the use of oxidisable solids, for example porous sachets containing iron powder. In another technique, oxidisable MXD-6 Nylon is blended with polyester in the walls of blow-moulded containers--the effectiveness of this depends on the presence of a cobalt salt catalyst, moreover the speed of oxygen removal is limited by the oxygen permeability of the polyester. Further methods include sandwiching crystalline oxidisable material between the layers of multilayer containers, and including a catalyst for the reaction of oxygen with hydrogen in a sandwich arrangement as above or as a deposit on the inner surface of the package.
Heterogeneous systems such as described above do not, however, adequately meet the general needs of the packaging industry, largely because they are often oxygen-sensitive prior to use or can be activated only under restricted conditions of, for example, temperature or humidity. One method which might be used to provide oxygen scavenging in packages as required, is disclosed in Rooney, M. L., Chemistry and Industry, Mar. 20, 1982, pp. 197-198. This method involves the inclusion of a photooxidizable rubber and a photosensitising dye into a polymer film packaging material and then exposing it to visible light. Similar methods are disclosed in Rooney, M. L. and Holland, R. V., Chemistry and Industry, Dec. 1979, pp. 900-901 and Rooney, M. L., Journal of Food Science, Vol. 47, No. 1, pp. 291-2294, 298. However, whilst these methods initiate oxygen scavenging upon illumination, they require constant illumination of the package in order to maintain the scavenging effect. U.S. Pat. No. 5,211,875 proposes an alternative method intended to avoid the problem of oxygen-sensitivity prior to use, involving an oxidizable organic compound (typically 1, 2-polybutadiene)and a transition metal catalyst (typically cobalt salt). Oxygen scavenging is initiated by exposing the composition to an electron beam, or ultraviolet or visible light.
SUMMARY OF THE INVENTION
However, the inclusion of a transition metal catalyst has a number of disadvantages including added cost, solubility difficulties, and a "gritty" appearance and reduced transparency of films made from such compositions. Some transition metal catalysts are also considered toxic and may not, therefore, be used with food.
The present invention avoids the disadvantages of including a transition metal catalyst. It may be based on plastic or other polymer-based compositions which can be activated as required, to effect reduction of ambient oxygen levels. The oxygen scavenging effect of the present invention also does not depend upon constant illumination with visible light.
Accordingly, in a first aspect the present invention provides a solid phase composition for reducing the concentration of ground state molecular oxygen present in an atmosphere or liquid, co
REFERENCES:
patent: 3615454 (1971-10-01), Cescon et al.
patent: 3768976 (1973-10-01), Hu et al.
patent: 3941759 (1976-03-01), Taylor et al.
patent: 4282111 (1981-08-01), Ciuba
patent: 4356301 (1982-10-01), Gleim
patent: 4555473 (1985-11-01), Dueber et al.
patent: 4847001 (1989-07-01), Cuisia et al.
patent: 4942112 (1990-07-01), Monroe et al.
patent: 5043166 (1991-08-01), Barenholz et al.
patent: 5098945 (1992-03-01), Pitteloud et al.
patent: 5147604 (1992-09-01), Ciuba et al.
patent: 5211875 (1993-05-01), Speer et al.
patent: 5354486 (1994-10-01), Evans
Rooney, M. L., "Measuring Packaging Film Attributes" Food Australia 41(8), Aug. 1989, pp. 880-881.
Holland et al., "New methods of measuring permeabilities of packaging films", CSIRO Fd. Res. Q. 1981, 41 pp. 47-50.
Rooney, M. L., "Photosensitive oxygen scavenger films: an alternative to vacuum packaging" CSIRO Fd. Res. Q 1983, 43 pp. 9-11.
Rooney, M. L., "New methods of maintaining product quality through packaging interaction" PA 1990--Session B-2.
Kirk-Othmer (1978) "Anthraquinone" Encyclopaedia of Chemical Technology (3rd Ed.) vol. 2, pp. 700-757.
Kirk-Othmer (1978) "Dyes, sensitizing" Encyclopaedia of Chemical Technology (3rd Ed.) vol. 8, pp. 393-408.
Rooney, M. L. (1995) "Active Food Packaging" pp. 1-33.
Rooney, M. L. (1995) "Active Food Packaging" pp. 74-110.
"Singlet Oxygen: An Intermediate in the Inhibition of Oxygen Permeation Through Polymer Films", by Michael L. Rooney et al, Chemistry and Industry, Dec. 15, 1979, pp. 900-901.
"Oxygen Scavenging from Air in Packaging Headspaces by Singlet Oxygen Reactions in Polymer Media", by Michael L. Rooney, Journal of Food Science, vol. 47, No. 1, Jan.-Feb. 1982, pp. 291-294, 298.
"Oxygen Scavenging: A Novel Use of Rubber Photo-Oxidation", by Michael L. Rooney, Chemistry and Industry, Mar. 20, 1982, pp. 197-198.
Patent Abstracts of Japan, C-138, p. 153, JP,A,57-145107, Sep. 8, 1982.
Anthony Joseph D.
Commonwealth Scientific and Industrial Research Organization
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