Stock material or miscellaneous articles – Structurally defined web or sheet – Including components having same physical characteristic in...
Reexamination Certificate
2000-05-23
2002-09-10
Kelly, Cynthia H. (Department: 1774)
Stock material or miscellaneous articles
Structurally defined web or sheet
Including components having same physical characteristic in...
C428S035700, C428S220000, C428S516000, C523S169000
Reexamination Certificate
active
06447892
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to packaging films, or more particularly to shrinkable, high gas barrier films containing an antifog composition for modified atmosphere packaging of foods and the like. The films are useful for producing a modified atmosphere package useful for the preservation and shelf life extension of food and non-food oxygen sensitive items.
2. Description of the Related Art
Containers have long been used to store and transfer perishable food prior to sale at a market where it will be purchased by the consumer. After perishable foods, such as meats, fruits, and vegetables, are prepared, they are placed into containers to preserve those foods for as long as possible. Maximizing the time in which the food remains preserved in the containers minimizes the amount of spoilage.
The environment around which the food is preserved is an important factor in the preservation process. Not only is maintaining an adequate temperature important, but the molecular and chemical content of the gases surrounding the food is significant as well. By providing an appropriate gas content to the environment surrounding the food, the food can be better preserved when maintained at the proper temperature or even when it is exposed to variations in temperature. This gives the food producer some assurance that the food will be in an acceptable condition when it reaches the consumer.
Preferred modified atmosphere packaging systems for foods, including raw meats, exposes these foods to extremely low levels of oxygen because it is well known that the freshness of meat can be preserved longer under anaerobic conditions than under aerobic conditions. Maintaining low levels of oxygen minimizes the growth and multiplication of aerobic bacteria.
Many multilayered films for modified atmosphere packaging systems are known. In this regard, U.S. Pat. No. 5,919,547 shows a laminate which delaminates into a substantially gas-impermeable portion and a gas-permeable portion. U.S. Pat. No. 6,060,136 teaches a multilayer film having first and second outer layers and an inner layer. The first and second outer layers comprise a homogeneous ethylene/alpha-olefin copolymer and the inner layer comprises a thermoplastic elastomer. This film is not taught to be heat shrinkable. U.S. Pat. No. 5,766,772 describes multi-layer heat-shrinkable film endowed with anti-fog properties having a different structure from this invention.
It would be advantageous to provide a multilayered packaging film which is heat shrinkable, sealable to a food container, an effective gas barrier and has effective antifog properties.
SUMMARY OF THE INVENTION
The invention provides a multilayered film which comprises a nylon film attached to a surface of an ethylene vinyl alcohol film and another nylon film attached to another surface of the ethylene vinyl alcohol film to form a composite; a surface of a polyolefin film attached to one of the nylon films via an intermediate adhesive, and an antifog composition on another surface of the polyolefin film or incorporated into the polyolefin film.
The invention also provides a process for producing a multilayered film which comprises coextruding a nylon film to a surface of an ethylene vinyl alcohol film and another nylon film to another surface of the ethylene vinyl alcohol film to form a composite; biaxially orienting the composite; laminating or coextruding a surface of a polyolefin film to one of the nylon films via an intermediate adhesive; and either applying an antifog composition onto another surface of the polyolefin film or incorporating an antifog composition into the polyolefin film.
The invention further provides a food package which comprises a container having an open portion and a multilayered film sealing the open portion; which multilayered film comprises a nylon film attached to a surface of an ethylene vinyl alcohol film and another nylon film attached to another surface of the ethylene vinyl alcohol film to form a composite; a surface of a polyolefin film attached to one of the nylon films via an intermediate adhesive, and an antifog composition on another surface of the polyolefin film or incorporated into the polyolefin film; the multilayered film being positioned such that the antifog composition is on the open portion.
The invention still further provides a multilayered film which comprises a shrinkable film attached to a surface of an oxygen barrier film and another shrinkable film attached to another surface of the oxygen barrier film to form a composite; a surface of a polyolefin film attached to one of the shrinkable films via an intermediate adhesive, and an antifog composition on another surface of the polyolefin film or incorporated into the polyolefin film.
The invention yet further provides a multilayered film which comprises a shrinkable film coated with an oxygen barrier coating and another shrinkable film attached to the oxygen barrier coating to form a composite; a surface of a polyolefin film attached to one of the shrinkable films via an intermediate adhesive, and an antifog composition on another surface of the polyolefin film or incorporated into the polyolefin film.
The multilayered packaging film of this invention is preferably heat shrinkable, sealable to a food container, an effective gas barrier and has effective antifog properties.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
In the production of the multilayered film according to the invention, first a nylon film is attached to a surface of an ethylene vinyl alcohol film and another nylon film attached to another surface of the ethylene vinyl alcohol film to form a composite.
The preferred nylon is a homopolymer or copolymer is selected from aliphatic polyamides and aliphatic/aromatic polyamides having a molecular weight of from about 10,000 to about 100,000. General procedures useful for the preparation of polyamides are well known to the art. Useful diacids for making polyamides include dicarboxylic acids which are represented by the general formula
HOOC-Z-COOH
wherein Z is representative of a divalent aliphatic radical containing at least 2 carbon atoms, such as adipic acid, sebacic acid, octadecanedioic acid, pimelic acid, suberic acid, azelaic acid, dodecanedioic acid, and glutaric acid. The dicarboxylic acids may be aliphatic acids, or aromatic acids such as isophthalic acid and terephthalic acid. Suitable diamines for making polyamides include those having the formula
H
2
N(CH
2
)
n
NH
2
wherein n has an integer value of 1-16, and includes such compounds as trimethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, octamethylenediamine, decamethylenediamine, dodecamethylenediamine, hexadecamethylenediamine, aromatic diamines such as p-phenylenediamine, 4,4′-diaminodiphenyl ether, 4,4′-diaminodiphenyl sulphone, 4,4′-diaminodiphenylmethane, alkylated diamines such as 2,2-dimethylpentamethylenediamine, 2,2,-trimethylhexamethylenediamine, and 2,4,4 trimethylpentamethylenediamine, as well as cycloaliphatic diamines, such as diaminodicyclohexylmethane, and other compounds. Other useful diamines include heptamethylenediamine, nonamethylenediamine, and the like.
Useful polyamide homopolymers include poly(4-aminobutyric acid) (nylon 4), poly(6-aminohexanoic acid) (nylon 6, also known as poly(caprolactam)), poly(7-aminoheptanoic acid) (nylon 7), poly(8-aminooctanoic acid)(nylon 8), poly(9-aminononanoic acid) (nylon 9), poly(10-aminodecanoic acid) (nylon 10), poly(11-aminoundecanoic acid) (nylon 11), poly(12-aminododecanoic acid) (nylon 12), as well as nylon 46, nylon 66 and nylon 69 and the like. Useful aliphatic polyamide copolymers include poly(hexamethylene adipamide) (nylon 6,6), poly(hexamethylene sebacamide) (nylon 6,10), poly(heptamethylene pimelamide) (nylon 7,7), poly(octamethylene suberamide) (nylon 8,8), poly(hexamethylene azelamide) (nylon 6,9), poly(nonamethylene azelamide) (nylon 9,9), poly(decamethylene azelamide) (nylon 10,9), caprolactam/hexamethylene adipamide copolymer
Gibboni David J.
Hatley Earl L.
Slotkin Alan
Ting Robert R.
Criss Roger H.
Honeywell International , Inc.
Kelly Cynthia H.
Nguyen Kimberly T.
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