Package making – Methods – With adsorption or absorption of contents
Reexamination Certificate
1999-06-24
2001-05-22
Gerrity, Stephen F. (Department: 3721)
Package making
Methods
With adsorption or absorption of contents
C053S432000, C053S1110RC, C252S188280
Reexamination Certificate
active
06233907
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates generally to a method and system of packaging oxygen sensitive materials, and particularly to a method and system for triggering an oxygen scavenging component of a container for containing oxygen sensitive materials.
It is well known that limiting the exposure of oxygen sensitive products to oxygen maintains and enhances the quality and shelf life of the product. For instance, by limiting the oxygen exposure of oxygen sensitive food products in the packaging system, the quality of the food product is maintained and spoilage is reduced. In addition, such packaging also keeps the product in inventory longer, thereby reducing costs incurred from waste and having to restock. At present, commonly used packaging systems include modified atmosphere packaging (MAP) and vacuum packaging in conjunction with oxygen barrier films. In these instances, reduced oxygen environments are employed at the time of packaging, while the oxygen barrier film reduces the amount of oxygen that physically enters the package during storage.
U.S. Pat. No. 5,211,875 to Speer et al. and PCT publication WO 94/12590 disclose methods and compositions for scavenging oxygen. The “oxygen scavenger” materials disclosed by Speer et al. are compositions which consume, deplete or reduce the amount of oxygen from a given environment.
Oxygen scavenging materials are useful in MAP and barrier packaging environments. However, problems are encountered when the oxygen scavenging material is a component of the inner wall of a pre-formed container. The difficulty arises in exposing the internal oxygen scavenging component to a uniform dosage of actinic radiation so that consistent initiation of oxygen scavenging activity across the internal surface is achieved.
The need remains for an effective method of triggering the oxygen scavenging activity of an internal oxygen scavenging component of a pre-formed container.
“Trigger” and the like herein mean that process defined in U.S. Pat. No. 5,211,875, whereby oxygen scavenging is initiated by exposing a composition, film, etc. to actinic radiation having a wavelength of less than about 750 nm at an intensity of at least about 1.6 mW/cm
2
or an electron beam at a dose of at least about 0.2 megarads, wherein after initiation the oxygen scavenging rate is at least about 0.05 cc oxygen per day per gram of oxidizable organic compound for at least two days after oxygen scavenging is initiated. Preferred is a method offering a short “induction period” (the time that elapses, after exposing the oxygen scavenging component to a source of actinic radiation, before initiation of the oxygen scavenging activity begins) so that the oxygen scavenging component can be activated at or immediately prior to use during filling and sealing of the container with an oxygen sensitive material; a method wherein the oxygen scavenging material is substantially consistently triggered across the entire internal surface of the preformed container; a method which is simple and readily incorporated into existing packaging procedures; and a method which is readily incorporated in-line into existing packaging systems.
SUMMARY OF THE INVENTION
According to a first aspect of the invention, a method for triggering an oxygen scavenging component of a container comprises the steps of providing a container defining an internal space and having an internal oxygen scavenging component comprising an oxidizable organic compound; and exposing said oxygen scavenging component to a source of actinic radiation, positioned within said internal space, at a wavelength, intensity, and residence time so as to provide a dose of actinic radiation sufficient to activate said oxygen scavenging component.
In a second aspect of the invention, a method for packaging an oxygen sensitive material, comprises the steps of providing containers each defining an internal space and having an internal oxygen scavenging component comprising an oxidizable organic compound; positioning a source of actinic radiation in said internal space of said containers; exposing said oxygen scavenging component to a dose of actinic radiation from said source of actinic radiation so as to provide containers each having a activated oxygen scavenging component; and feeding said containers to means for filling and sealing said containers so as to provide sealed containers wherein said oxygen scavenging component scavenges oxygen from said internal space.
In a third aspect of the invention, an apparatus for triggering an oxygen scavenging component of a container comprises means for emitting actinic radiation sufficient to activate an oxygen scavenging material comprising an oxidizable organic compound; and means for positioning a container defining an internal space and having an oxygen scavenging component relative to said means for emitting so as to position said means for emitting in said internal space of said container, whereby said internal oxygen scavenging component is exposed to a substantially uniform dose of actinic radiation from said means for emitting.
In a fourth aspect of the invention, a packaging system comprises means for emitting actinic radiation; means for positioning containers, said containers having an oxygen scavenging component and defining an internal space for containing an oxygen sensitive material, relative to said means for emitting with said means for emitting in said internal space whereby said oxygen scavenging component is exposed to a dose of actinic radiation; means for filling said containers with an oxygen sensitive material and for sealing said container containing said material; and means for conveying said containers from said means for emitting to said means for filling, whereby said containers are filled and sealed and said oxygen scavenging component scavenges oxygen from said internal space.
REFERENCES:
patent: 5021515 (1991-06-01), Cochran et al.
patent: 5089323 (1992-02-01), Nakae et al.
patent: 5211875 (1993-05-01), Speer et al.
patent: 5310497 (1994-05-01), Ve Speer et al.
patent: 5350622 (1994-09-01), Speer et al.
patent: 5378428 (1995-01-01), Inoue et al.
patent: 5399289 (1995-03-01), Speer et al.
patent: 5417255 (1995-05-01), Sanfilippo et al.
patent: 5425896 (1995-06-01), Speer et al.
patent: 5498364 (1996-03-01), Speer et al.
patent: 5776361 (1998-07-01), Katsumoto et al.
patent: 5799463 (1998-09-01), Kasiba
patent: 5811027 (1998-09-01), Speer et al.
patent: 5811144 (1998-09-01), Bordeleau et al.
patent: 5911910 (1999-06-01), Becraft et al.
patent: 0 355 982 (1990-02-01), None
patent: 0 451 762 A2 (1991-10-01), None
patent: WO 94/12590 (1994-06-01), None
Japanese Abstract Hei 5-247276; Nakamura et al.; Mar. 4, 1992; “Oxygen Barrier Resin Composition”.
Japanese Abstract Hei 5-51048; Masuda et al.; Aug. 13, 1991; “Oxygen Barrier Resin Composition, Manufacturing Process and Packaging Material Thereof”.
Japanese Abstract Hei 5-51049; Tomatsuri et al.; Aug. 13, 1991; “Sheet and Container Possessing Oxygen Barrier Property”.
Japanese Abstract Hei 5 32277, Yasunaga, Dec. 28, 1990; “Method for Removal of Oxygen Remained in a Package and a Package Member”.
Carey Michael J.
Cook, Jr. Philip H.
Miranda Nathanael R.
Thomas Jeffrey A.
Cryovac Inc.
Gerrity Stephen F.
Quatt Mark B.
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