Stock material or miscellaneous articles – Hollow or container type article – Polymer or resin containing
Reexamination Certificate
1999-05-06
2002-05-14
Pyon, Harold (Department: 1772)
Stock material or miscellaneous articles
Hollow or container type article
Polymer or resin containing
C428S457000, C252S188280, C206S524600
Reexamination Certificate
active
06387461
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to novel compositions and processes of scavenging oxygen to improve product quality and shelf life of oxygen sensitive materials. The compositions can be formed into films, coatings, 3-dimensional solids, fibers, webs, and shaped products or structures which are incorporated into, applied to, or otherwise become a part of a container structure.
BACKGROUND OF THE INVENTION
In order to enhance preservation, it is standard practice to package food and other materials within laminated packaging material that generally includes a barrier layer, that is, a layer having a low permeability to oxygen. The sheet material can be thin, in which event it is wrapped around the material being packaged, or it can be sufficiently thick that it forms a shaped container body that is provided with a lid or other separate closure. The polymeric sheet material may constitute some or all of the interior exposed surface area of the container or its closure means.
It is known to include an oxygen scavenger agent in sheet material. The oxygen scavenger agent reacts with oxygen that is trapped in the package or that permeates into the package. This is described in, for instance, U.S. Pat. Nos. 4,536,409 and 4,702,966 and the prior art discussed in these references. U.S. Pat. No. 4,536,409, for example, describes cylindrical containers formed from such sheet material and provided with metal lids.
When the container is formed of a glass or metal body and is provided with a hermetically sealed metal closure, the permeation of oxygen through the body and the closure is theoretically impossible because of the impermeability of the materials forming the body and closure. As a practical matter, metal cans can reliably prevent oxygen ingress. However, some oxygen ingress may occur by diffusion through the gasket or the like positioned between a container body and its lid or end portion. It has long been recognized that when conventional containers of these types are used for the storage of oxygen sensitive materials, the shelf life of the stored materials is very limited. The quality of the packaged material tends to deteriorate over time, in part because dissolved oxygen typically is present in the container from the time it is filled; and in part due to oxygen ingress which occurs during storage.
When the container is a can, the can end or other closure often includes push and pull components which are manipulated by pushing and/or pulling to permit removal of a fluid or other material from the container without removing the entire closure from the container. These push or pull components are often defined by discontinuities or lines of weakness in the panel of the closure. Problems that can arise at these lines of weakness or discontinuities include the risk of permeation of oxygen into the container and the risk of oxidation corrosion of the metal where the normal protective lacquer coating is ruptured at the lines of weakness or discontinuities.
It is desirable to extend shelf life or packaged products using materials capable of being fabricated into or as part of a film, liner material, closure, gasket or other member of a package intended for storage of oxygen sensitive products.
Various types of oxygen scavengers have been proposed for this purpose. For example, it is well known to package iron powder in a sachet for this purpose. See Mitsubishi Gas Chemical Company, Inc.'s literature titled “Ageless®—A New Age in Food Preservation” (date unknown). These materials require the addition of water soluble salts to enhance the oxygen scavenging rate. However, in the presence of moisture, the salts, and iron and its oxides tend to migrate into liquids, producing off-flavors. Similarly, U.S. Pat. No. 4,536,409 issued to Farrell et al. recommends potassium sulphite as a scavenger, with similar results.
It is known in the art that ascorbic acid derivatives (ascorbic acid, its alkali metal salts, optical isomers, and derivatives thereof) as well as sulfites, bisulfites, phenolics, etc. can be oxidized by molecular oxygen, and can thus serve as an oxygen scavenging material. For example, U.S. Pat. No. 5,075,362, issued to Hofeldt et al., discloses the use of ascorbate compounds in container closures as oxygen scavengers.
U.S. Pat. No. 5,284,871 issued to Graf relates to the use of an oxygen scavenging composition made of a solution of a reducing agent and dissolved species of copper which are blended into foods, cosmetics and pharmaceuticals. Copper ascorbate is used in the examples. The reference indicates that relatively high levels of Cu
2+
(~5 ppm) are required in the food for scavenging to be effective but if small amounts of the Cu
2+
are used, it may combine with oxygen in the packaged food to cause food spoilage. In order to avoid spoilage, one is required to reduce the amount of headspace O
2
by some other means such as by partially flushing the container with an inert gas (See U.S. Pat. No. 5,284,871 at Col. 5, lines 32-39). A paper by E. Graf, “Copper (II) Ascorbate: A Novel Food Preservation System”, Journal of Agricultural Food Chemistry, Vol. 42, pages 1616-1619 (1994) identifies copper gluconate as a preferred raw material.
The scientific literature (See “Polymer Compositions Containing Oxygen Scavenging Compounds”, Teumac, F. N.; et al. WO 91/17044, published Nov. 4, 1991, filed on May 1, 1991) discloses that oxidation rates of ascorbate compounds can be increased by the use of catalysts. Typical catalysts for ascorbic acid and its derivatives are water soluble transition metal salts.
In each of the above references, the active component of the oxygen scavenging systems utilized agents which readily transfer into the food or other packaged product or materials or which produce oxidation by-products which are known to adversely affect a wide range of packaged material.
It is highly desired to provide an effective oxygen scavenging composition which has a high oxygen absorption rate and capacity.
It is also highly desired to provide an effective oxygen scavenging composition which has a high oxygen absorption rate and capacity and which does not adversely effect the color, taste or smell of packaged material.
It is further desired to provide an effective oxygen scavenging composition which has the active oxygen scavenger material contained within a carrier suitable for forming at least a part of a package or container article and to have the material provide effective scavenging activity and capacity.
It is still further desired to provide an effective oxygen scavenging composition which is thermally stable and, thereby, capable of being formed and processed at elevated temperatures.
SUMMARY OF THE INVENTION
The present invention is directed to a composition comprising a carrier having uniformly distributed therein an oxygen scavenging system capable of exhibiting high initial oxygen scavenging activity and enhanced oxygen scavenging capacity while avoiding undue migration of the components of the composition and its oxidation by product(s) from the carrier. The inhibition to migration significantly reduces or eliminates adverse effects of color, taste and smell of packaged articles which are in contact with or contained in a container having said composition. Specifically, the present composition comprises a carrier having a combination of hydroxosulfitometalate and a transition metal ion source, as fully described herein below.
The present invention is further directed to shaped structures containing or derived from the subject composition. Such structures can comprise one or more layers of a film suitable for forming a closed package (e.g., pouch) as well as semi rigid or rigid containers, including closures, such as closure sealants, closure gaskets, fluid-applied sealant compositions (e.g., melt-applied crown cap gasket compositions), cap liner discs, and the like, formed with or containing the subject composition.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention is directed to an oxygen scavenging com
Ebner Cynthia Louise
Hallock John Scott
Cryovac Inc.
Hon Sow-Fun
Pyon Harold
Quatt Mark B.
LandOfFree
Oxygen scavenger compositions 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 scavenger compositions, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Oxygen scavenger compositions will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2842941