Compositions – Reductive bleachant – deoxidant – reductant – or generative – Deoxidant or oxygen scavenging
Reexamination Certificate
1999-06-03
2003-07-22
Mulcahy, Peter D. (Department: 1713)
Compositions
Reductive bleachant, deoxidant, reductant, or generative
Deoxidant or oxygen scavenging
C524S435000, C524S440000
Reexamination Certificate
active
06596191
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an oxygen absorbing composition having an oxygen absorbing ability in a low-humidity environment, and to an oxygen absorbing resin composition including such a composition and thermoplastic resin. More particularly, the present invention relates to an oxygen absorbing composition including iron powder and iodine, or an oxygen absorbing composition including iron powder, iodine and metal iodide, and also to an oxygen absorbing resin composition including the oxygen absorbing composition above and thermoplastic resin.
Furthermore, the present invention relates to a product preserving method using the aforementioned oxygen absorbing composition or oxygen absorbing resin composition, especially to a method of preserving medicines or foods etc. which are in a dry state and disfavoring moisture.
2. Description of Related Art
Conventionally, oxygen absorbers utilizing the oxidizing reaction of reduced metals have been widely known. In addition to reduced metal, these oxygen absorbers include metal halide as a catalyst for accelerating oxidizing reaction.
Oxygen absorbers of this type are placed in containers together with food or other products so as to maintain the freshness of such products. In other cases they are adhered to the inside of the containers for the purpose of preserving food or other products.
A typical oxygen absorber of this type is disclosed, for example, in the Japanese Patent (Kokoku) Publication No. SHO 56-33980. This oxygen absorber includes metal powder such as iron powder, and metal halide. More specifically, the oxygen absorber has a structure of metal powder coated with metal halide. An oxygen absorber of this type requires supply of water from the environment upon absorption of the oxygen, and therefore, is called a “moisture-dependent oxygen absorber.” Such an oxygen absorber is used for high water-content foods which permit use of water vaporizing from the preserved product.
On the other hand, in order to preserve dried foods etc. having a low water content (in other words, having low water activity), a typical oxygen absorber includes a water provider for supplying water needed for the oxygen absorbing reaction. An oxygen absorber of this type is known as a “self-reacting oxygen absorber” because it is capable of absorbing oxygen without depending on the water vaporing from the packaged substance. Such an oxygen absorber is disclosed in the Japanese Patent (Kokoku) Publication No. SHO 57-31449.
Furthermore, oxygen absorber packets, which are oxygen absorbing resin sheets wrapped in a gas-permeable packaging material and used as a label-, card-, or lid-type, or other types of oxygen absorber for deoxidizing and preserving food or other products are disclosed in the Japanese Patent Laid-Open Publications No. HEI 2-72851, No. HEI 7-137761, No. HEI 7-219430, etc.
However, if a self-reacting oxygen absorber holding water in itself is kneaded into resin, there is a concern that moisture held in the water-holding component might vaporize when heat is applied at the time the oxygen absorber is kneaded and made into a sheet. Furthermore, the vaporized moisture may produce foam inside the resin sheet and cause unevenness of the sheet upon extrusion, whereby formation of the sheet is made difficult.
Moreover, although a self-reacting oxygen absorber is capable of absorbing oxygen regardless of the relative humidity of the environment, moisture included in the oxygen absorber will inevitably vaporize during oxygen absorption and be transferred to the products preserved. Accordingly, there is a problem that the oxygen absorber may not be used if the products preserved are medicines and foods etc. which are in a dry state and disfavoring moisture.
Furthermore, in the case of a moisture-free oxygen absorber, it is possible to include moisture in the aforementioned oxygen absorber after It is kneaded with resin and made into a sheet. However, such a treatment requires a separate step in addition to the steps of manufacturing the oxygen absorber, and is therefore disadvantageous in the industrial manufacture. Furthermore, if an oxygen absorber provided with such a treatment is used for dried products, it is inevitable that moisture held in the oxygen absorber would vaporize and be transferred to the preserved product. Moreover, in the case of some preserved products, transfer of moisture may cause deterioration of taste (dampening), change in quality (powder formed into lumps), chemical change (hydrolysis) and other problems. Furthermore, there is a problem that moisture will vaporize from the oxygen absorber in the course of long-term preservation and the oxygen absorbing performance is reduced, whereby absorption of the oxygen intruding from outside of the container is prevented, the oxygen concentration inside the container is prevented, and the quality of the product preserved is consequently deteriorated.
Furthermore, in the case of an oxygen absorbing multilayered body comprising an oxygen absorbing resin composition as a middle layer, a barrier layer as an outer layer and a seal layer as an inner layer, it is quite difficult to keep moisture in the oxygen absorber layer which is provided as the middle layer.
Accordingly, application of conventional oxygen absorbing resin compositions has been substantially limited to high water-content products, while application to low water-content products has been difficult.
SUMMARY OF THE INVENTION
The inventors of the present invention discovered that a new oxygen absorber comprising either iron powder/iodine or iron powder/iodine/metal iodide is capable of rapid oxygen absorption without any water provider even in a low-humidity environment. Free from a concern that moisture may be absorbed by the products preserved, this new oxygen absorber is most suitable for the deoxidization and preservation of food in a dry state. The aforementioned oxygen absorber, which includes iodine or iodine/metal iodide, functions as an accelerator of the oxygen absorption reaction by iron.
The inventors of the present invention further discovered that especially iron powder coated with iodine or metal iodide salt may be favorably blended into resin, made into a sheet and thereafter drawn, and that such an oxygen absorbing resin composition is also capable of absorbing oxygen in a low-humidity environment.
As an oxygen absorber not requiring any water provider, the present invention permits preservation of products of a wider water-activity range. Especially, products having a water activity of 0.1 to 0.7, disfavoring moisture and requiring a dry environment of low humidity upon preservation, for example, dietary foods or powder- or granular-type medicines etc. may be preserved for a long time in a deoxidized state without any moisture being absorbed, whereby deterioration due to oxygen is prevented and the favorable quality of the products may be maintained.
Thus, the present invention provides an oxygen absorbing composition and an oxygen absorbing resin composition employing such oxygen absorbing composition, which demonstrate a sufficient deoxidizing performance even in a low-humidity environment.
Furthermore, the present invention provides a preserving method using an oxygen absorbing composition and an oxygen absorbing resin composition employing such oxygen absorbing composition.
More specifically, the present invention provides an oxygen absorbing composition which comprises iron powder and iodine.
Moreover, the present invention provides an oxygen absorbing composition comprising iron powder, iodine, and metal iodide.
The aforementioned metal iodide may be metal iodide of alkaline metal or metal iodide of alkaline earth metal.
Furthermore, the aforementioned metal iodide of alkaline metal or alkaline earth metal may be sodium iodide, potassium iodide, or calcium iodide.
Furthermore, the sum of the weights of iodine and metal iodide is 0.01 to 20 parts by weight per iron powder 100 parts by weight, and the weight ratio of iodine to metal iodide may
Nagata Masaki
Sakamoto Masaru
Mitsubishi Gas Chemical Company Inc.
Mulcahy Peter D.
Nixon & Peabody LLP
Stamper Adele M.
LandOfFree
Oxygen absorbing composition, oxygen absorbing resin... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Oxygen absorbing composition, oxygen absorbing resin..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Oxygen absorbing composition, oxygen absorbing resin... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3010084