Food or edible material: processes – compositions – and products – Packaged or wrapped product – Three or more layered packaging materials
Reexamination Certificate
1997-11-14
2001-12-25
Pyon, Harold (Department: 1772)
Food or edible material: processes, compositions, and products
Packaged or wrapped product
Three or more layered packaging materials
C206S497000, C426S130000, C426S415000, C428S034900, C428S035400, C428S036600, C428S036700, C428S475800, C428S476900, C428S483000, C428S515000, C428S516000, C428S518000, C428S520000
Reexamination Certificate
active
06333061
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an article comprising a multilayer film suitable for packaging end use, especially a multilayer film suitable for use in the packaging of relatively hard, granular bulk products, such as dry pet food. The article comprises a heat seal of the film to itself or another film, preferably, in the form of a gusseted bag. The present invention also relates to packaged products in which the package comprises the article of the invention.
BACKGROUND OF THE INVENTION
For some time various products have been packaged in packages which comprise paper alone or paper in combination with a thermoplastic film. Such packaging has typically included a plurality of paper layers, with a relatively thin, flexible plastic film adhered to the inside paper layer, the film serving as a moisture and grease barrier. The paper provides the package with an exterior surface which is highly printable, as well as a stiffness which provides the packaging article, which is, for example, a gusseted bag, with an ability to be self-supporting and to provide the package with overall aesthetic qualities which consumers perceive as being desirable. Such paper packaging has been used in a variety of applications, particularly gusseted bags which are used in the packaging of dry granular material such as pet food, livestock feed, sugar, coffee, cookies, cereals, baking products such as cake mixes, crackers, chips, powdered milk, charcoal, cement, fertilizer, lime, pesticides, etc. The packaging can also be used to package cheese, in grated, ground, and/or block form.
More recently, paper-free plastic film packaging materials have been used for the packaging of a such products as pet food, etc. In order to obtain a desirable performance level, i.e., in terms of impact strength and toughness, such packaging films have contained relatively large quantities of polymers which are recognized for their toughness and impact resistance, such as polyamide, polyester, and polyacrylonitrile. However, these polymers are also relatively expensive. It would be desirable if a comparably tough, impact-resistant package could be made from less expensive polymers. Moreover, it would also be desirable to provide packaging which provides a high O
2
-barrier layer to increase the shelf-life of the product. In addition, in such plastic packaging, particularly in the packaging of hard, granular bulk products such as dry pet food, it has been found that “dimples” tend to form in the plastic, thereby creating a rough, dimpled appearance in the outside of the package. It would be desirable to provide packaging which avoids this “dimpling” effect. Finally, it would be desirable to provide such packaging which is also relatively stiff, e.g., capable of providing a self-supporting gusseted bag.
In the case of the packaging of food in paper packaging, particularly pet food, it has heretofore been desirable to mix antioxidant into the food product; otherwise the food tends to lose metabolizable energy, exhibit decreased acceptability, including undesirable odors and flavors, protein degradation, and the development of health hazards in the consuming animal. Thus, without antioxidant present, food packaged in paper packaging exhibits reduced shelf-life and/or reduced product quality. It would be desirable to provide a type of packaging which requires less antioxidant, or even no antioxidant, to be mixed with a food product within the package, without the detrimental effects associated with the oxidation of the food product. In this manner, the expense of providing the antioxidant as well as the mixing of the antioxidant with the food product, are both reduced or avoided, while maintaining a good shelf life for the packaged food product.
SUMMARY OF THE INVENTION
The present invention is directed to an article which is suitable for packaging end-use and which comprises a multilayer film. The majority of the multilayer film is made from relatively inexpensive polymers. Nevertheless, it has been found that the multilayer film can be provided with toughness and impact resistance characteristics which are adequate for the packaging of various product, including dry pet food. Moreover, it has been found that the multilayer film can be provided with toughness and impact resistance characteristics which are comparable to, or even superior to, plastic packaging materials which comprising higher amounts of more expensive polymers such as nylon, polyester, and polyacrylonitrile.
In addition, the multilayer film in the article of the present invention can be provided with an O
2
-barrier layer which increases the shelf life of, for example, a packaged food product therein. The presence of the O
2
-barrier layer reduces or eliminates the need to add antioxidants, etc. to a food product, such as pet food, to prevent the oxidative rancidity, off-flavors, and off-odors of the packaged food product. The multilayer film also can be provided with a stiffness which, if the multilayer film is converted to a gusseted bag which is self-supporting. The multilayer film can also be provided with: (a) high gloss, to provide a packaged product having enhanced aesthetic appeal; (b) high resistance to tear propagation; (c) printing on the surface of the film, and/or printing which is trapped between the layers of the film; and (d) high impact strength.
As a first aspect, the present invention is directed to a sealed article comprising a multilayer film. The multilayer film comprises at least 4 layers. The first film layer which is an inside film layer comprising at least one member selected from the group consisting of ethylene/alpha-olefin copolymer and polystyrene; the second film layer comprises at least one member selected from the group consisting of ethylene/unsaturated ester copolymer, anhydride-modified ethylene/alpha-olefin copolymer, anhydride-modified ethylene/ester copolymer, acid-modified ethylene/alpha-olefin copolymer, acid-modified ethylene/acid copolymer; the third film layer comprising at least one member selected from the group consisting of ethylene/alpha-olefin copolymer and polystyrene; the fourth film layer which is an outside layer comprising at least one member selected from the group consisting of ethylene homopolymer, ethylene/alpha-olefin copolymer, ethylene/vinyl alcohol copolymer, polyvinylidene chloride, polyamide, polyester, polyalkylene carbonate, polyacrylonitrile, and ethylene/unsaturated ester copolymer. At least 85 percent of the film, based on total film volume, is made of (i.e., consists of) at least on member selected from the group consisting of polyolefin homopolymer, polyolefin copolymer, ethylene/ester copolymer, polystyrene, styrene/butadiene copolymer, EVOH, PVDC, and polyacrylonitirile. This composition is preferably from about 85-100 volume percent; more preferably, from about 87 to 100; still more preferably 89-100; yet still more preferably, from about 90-100; even yet still more preferably, from about92-100; and even still more preferably, from about 95-100 volume percent. In addition, the film has a total thickness of at least 2 mils, and an impact strength of at least about 1.5 ft-lbs (preferably, at least 1.6 ft-lbs; more preferably, at least 1.7 ft-lbs). The article comprises a heat seal of the film to at least one member selected from the group consisting of itself and another film.
Preferably, the film has an impact strength of from about 1.5-20 fl-lb; more preferably, from about 2-5 ft-lb. Preferably, the film has a ball burst impact strength of from about 10 to 70 cm-kg, more preferably from about 20 to 60 cm-kg; still more preferably, from about 30 to 50 cm-kg.
Preferably, the first and third film layers further comprise ethylene/unsaturated ester copolymer. Preferably, the seal is a heat seal. Preferably, the article comprises a heat seal of the film to itself.
Preferably, the first film layer is directly adhered to the second film layer; the third layer is directly adhered to the second layer; the third layer is between the second layer and the fourth layer. Prefe
Cryovac Inc.
Hurley Jr. Rupert B.
Nolan Sandra M.
Pyon Harold
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