JP2007514168A - Leakage detection method for sealed packaging - Google Patents

Abstract

The present invention relates to a method for detecting leaks in packaging. This method, (i) O 2 _- sensitive indicator, leak indicator layer present over the leak indicator layer, and (ii) the outer leak indicator layer O ₂ - a multilayer film comprising a barrier layer, O ₂ - Preparing a package by covering at least a portion of the sensitive product. A low O ₂ -environment is provided in the package. Leakage indicator layer. A low O ₂ -environment is provided in the package. Leak indicator layer is then, O 2 _- sensitive indicator, O 2 _- to emit radiation in an amount inversely proportional to the level of O ₂ present with sensitive indicator, O 2 _- is absorbed by the sensitive indicator Irradiated with light containing wavelength. Then, the multilayer film, O 2 _- is scanned while sensitive indicator emits radiation, scanning is carried out by sensing and comparing the amount of radiation emitted from at least two different regions of the multilayer film.

Description

  The present invention relates to a method for detecting leaks in a package comprising an oxygen-sensitive product, ie a package having a low oxygen content inside.

  Oxygen damages many products. Food, beverages, pharmaceuticals, medical devices, corrosive metals, analytical chemicals, electronic devices, and many other products can have a reduced shelf life, such as corrosion, when stored for long periods in the presence of oxygen. To counter this problem, packaging manufacturers have developed packaging materials and systems to protect these products by providing a packaging environment, i.e., an "upper space" with reduced oxygen levels. It was.

  Low oxygen levels can be obtained by packaging under vacuum or by replacing air and replacing the food with denatured air (low oxygen). In many cases, the low oxygen levels obtainable with these packaging systems are still insufficient to provide the desired shelf life.

  If a vacuum package or modified air package leaks and oxygen is put into the package, the oxygen content in the package will eventually increase, resulting in detrimental results for the shelf life of the product. It is known to use porphyrins as indicators that can inform the level of oxygen in the package. Porphyrins are excited by irradiation and the extent of subsequent radiation emission (ie, phosphorescence) is inversely proportional to the level of oxygen in the package. However, if the rate of oxygen ingress into the leaky package is slow, it may take a significant amount of time for the oxygen content inside the package to increase substantially. It is desirable to be able to quickly determine if the package is leaking immediately after the packaging is complete. It is also desirable to accurately determine the location of leakage in the packaging.

  The method of the present invention provides a means by which the presence of a leak and the location of the leak can also be determined in a vacuum package or modified air package without breaking the package. In this way, packaging leaks can be inspected repeatedly at different points in the distribution channel and also by the end consumer. This method can check for the presence of a package leak before there is any significant increase in oxygen levels inside the package.

  The method of the present invention involves the use of a multilayer film surrounding at least a portion of the product, the film having an oxygen barrier layer on the outside of a second film comprising an indicator material, such as porphyrin. If there is a leak in the film or in the seal to the film itself or in other components of the package, the porphyrin is inversely proportional to the oxygen content at that position by irradiation of the film to activate the porphyrin. Emits a certain amount of phosphorescence. Small leaks in the packaging do not phosphorize the porphyrin around the leak or cause it to phosphorize at a low level. This lack or reduced phosphorescence of phosphorescence can be detected as a “gray spot” by scanning the package. The scanning can be done manually, i.e. with the naked eye, or via machine images. In this way, immediately after packaging, the package can be inspected for the presence of leaks and, if a leak is found, can be repackaged immediately. Similarly, after shipping to distribution and / or retail locations, the packaging can be retested to determine the presence of leaks that may have occurred during handling or transport. Similarly, the consumer rechecks the product for leaks at the retail store to ensure that the packaging was effective in maintaining a low oxygen environment to prevent product degradation. You can also.

As a first aspect, the present invention relates to a method for detecting leakage in packaging. The method includes (A) (i) a leak indicator layer in which the O ₂ -sensitive indicator is present throughout the leak indicator layer, and (A) (ii) an O ₂ -barrier layer outside the leak indicator layer. A step of preparing a package by covering at least a part of an O ₂ -sensitive product with a multilayer film (A); a step of preparing a low O ₂ environment in the package (B); an O ₂ -sensitive indicator, O 2 _- to emit radiation in an amount inversely proportional to the level of O ₂ present with sensitive indicator, a leak indicator layer, O 2 _- irradiating with light including wavelengths absorbed by the sensitive indicator (C ); And the O ₂ -sensitive indicator scans the multilayer film while emitting radiation, and the scanning senses and compares the radiation dose emitted from at least two different regions of the multilayer film Step (D) to be performed is included. Preferably, at least 25% of the product is covered with film, more preferably at least 50%, more preferably at least 75%, more preferably 100%.

Preferably, the low O ₂ -environment is (i) collecting O ₂ inside the package by preparing the package together with an O ₂ -collecting agent, and (ii) exhausting air from within the package. And (iii) by performing at least one action selected from the group consisting of replacing atmospheric O ₂ in the package.

The results of sensing and comparing radiation emitted from at least two different scanning areas correlate with the absence of leakage in the package. Alternatively, the results of sensing and comparing radiation emitted from at least two different scanning areas correlate with the presence of at least one leak in the package. If leakage is detected, preferably, O ₂ in the packaging having at least one leakage - is sensitive product, is removed from the packaging, is repackaged in a new packaging.

  Leakage can include at least one hole in the multilayer film or at least one discontinuity in the seal to the film itself or other component of the packaging.

  Preferably, the package has a seal that is a heat seal.

Preferably, sensing and comparison is performed so that both the presence and location of at least one leak of air O _{2 in} the package can be determined.

Preferably, packaging, O ₂ in the bag made by sealing the multilayer film to itself - housing a sensitive product, and then the air is discharged from the bag, while discharging the air from the bag, Made by sealing the inner layer of the bag to itself across the open tip of the bag. Preferably, the multilayer film is in both a machine direction and a lateral direction in a manner further comprising heat shrinking the film after the inner layer of the bag is sealed to itself across the open tip of the bag. , At 185 ° F. with at least 5% free shrinkage. Preferably, the product comprises meat, more preferably red meat, more preferably beef, pork, lamb and / or chicken.

Alternatively, O 2 _- sensitive product is a non-food product such as a DVD.

  Optionally, the package includes a bottom forming portion and a lid stock that is sealed to the bottom forming portion, the lid stock including a multilayer film. Preferably, the bottom forming part is a tray, preferably a polystyrene tray, more preferably a polystyrene foam tray.

  In one preferred embodiment, the packaging includes denatured air.

In one preferred embodiment, O 2 _- sensitive indicator is printed on the film.

In one preferred embodiment, O 2 _- sensitive products, to collect the packaging inner O _2. Such products include beef, pork, chicken and fish.

In one preferred embodiment, packaging, O 2 _- comprises a tray with a barrier liner, the tray has a flange, O 2 _- sensitive products present on the tray, the multilayer film covers the product, Bonded to the tray flange.

In one preferred embodiment, _{O 2} - barrier layer, 25 ℃, 0% RH, in 1atm (ASTM D 3985), has a 100cc ^/ m ^2/24 hours or less of oxygen transmission rate, _{O 2} - barrier Layers are polyester, polyamide, ethylene vinyl alcohol copolymer, polyvinyl alcohol homopolymer, polyvinyl chloride, polyvinylidene chloride homopolymer and copolymer, polyethylene naphthalate, polyacrylonitrile homopolymer and copolymer, liquid crystal polymer, SiO _x , carbon, metal And at least one material selected from the group consisting of metal oxides.

In one preferred embodiment, the O ₂ -sensitive indicator is at least selected from the group consisting of octaethylporphyrin, tetraphenylporphyrin, tetrabenzoporphyrin, or chlorin, bacteriochlorin, or a metallo derivative of this isobacteriochlorin. Contains one material.

In one preferred embodiment, the O ₂ -sensitive indicator comprises porphyrin.

  In one preferred embodiment, the film surrounds the food product.

  In one preferred embodiment, air is exhausted between the food and the film.

In one preferred embodiment, air is present between the food product and the multilayer film, and the air comprises O ₂ in an amount of less than 5% by weight.

In one preferred embodiment, the film is
i) an oxidizable organic compound and a transition metal catalyst,
ii) ethylenically unsaturated hydrocarbons and transition metal catalysts,
iii) a reduced form of a quinone, a photoreducible dye, or a carbonyl compound having absorption in the UV spectrum,
iv) a polymer backbone, a cyclic olefinic pendant, and a polymer having a linking group that connects the olefinic pendant to the polymer backbone;
v) a copolymer of ethylene and distorted cyclic alkylene, and vi) an ethylene / vinyl aralkyl copolymer,
vii) ascorbate,
viii) isoascorbate,
ix) sulfite,
x) ascorbate and a transition metal catalyst (wherein the catalyst comprises a single metal or salt of a transition metal or a compound, complex or chelate),
xi) transition metal complexes or chelates of polycarboxylic acids, salicylic acids, or polyamines,
and xii) tannin, and xiii) an O ₂ -catalyst comprising at least one material selected from the group consisting of reduced metals.

  In one preferred embodiment, the oxygen indicator and oxygen scavenger are present in the form of a blend. Preferably the blend is present in one layer of the film.

  In one preferred embodiment, the oxygen indicator is encapsulated with an adhesive.

  The accompanying figures illustrate several embodiments of the present invention.

  As used herein, terms such as “heat-shrinkable film”, “heat-shrinkable film” mean a film oriented in the solid state (in contrast, blown film is above the melting point of the polymer, Or oriented in the vicinity). The tension in heat shrinkable films increases with the application of heat when the film is restrained by shrinkage. As a consequence, the term “heat-shrinked” means that the film or a part thereof is in a heat-shrinked state, ie reduced (unsuppressed) or under increased tension (suppressed) in size. Means a heat-shrinkable film, or part thereof, exposed to heat as in Preferably, the heat shrinkable film is at least 5% at 185 ° C., more preferably at least 7%, even more preferably at least 10%, even more preferably at least 15%, even more preferably at least 20 % Total free shrinkage (ie machine direction + lateral direction) with free shrinkage in each direction (measured according to ASTM D2732). The total free shrinkage at 185 ° F. can be 10 to 150%, more preferably 20 to 120%, more preferably 40 to 100%.

  As used herein, the terms “inner surface layer” and “inner layer” refer to any layer of a multilayer film, both of which have a major surface directly adhered to another layer of the film.

  As used herein, the term “outer surface layer” means any film layer of a film whose major surface is directly bonded to another layer of the film and has no more than 1 and less than 2. The term includes single layer and multilayer films. In a multilayer film, there are two outer layers, each having a major surface that is adhered to only one other layer of the multilayer film. In a monolayer film, of course, there is only one layer, which is the outer surface layer of either of the two major surfaces that is not adhered to another layer of the film.

  As used herein, the term “inner layer” refers to the outer surface layer of a multilayer film packaging the product that is closest to the product with respect to the other layers of the multilayer film.

  As used herein, the term “outer layer” refers to the outer surface layer of a multilayer film packaging the product that is farthest from the product with respect to the other layers of the multilayer. Similarly, the “outer surface” of the bag is the surface away from the product packaged in the bag.

  As used herein, the term “glued” refers to films that are directly adhered to each other using heat sealing or other means, and to each other using an adhesive between the two films. Including film.

  Although the film used in the method of the present invention can be a single layer film or a multilayer film, the patch bag comprises at least two films laminated together. Preferably, the patch bag consists of a film comprising a total of 2 to 20 layers, more preferably 2 to 12 layers, and even more preferably 4 to 12 layers together. In general, the multilayer film used in the present invention is a film that has desirable properties for the particular packaging operation in which the film is used, such as overuse resistance (especially perforation resistance), modulus, seal strength, optics, etc. As long as it is provided, it can have any desired total thickness.

The term “low O ₂ -environment” as used in the present invention means that the air is being exhausted, replaced by another environment, or the O ₂ -catalyst activity reduces the O ₂ content. Means a denatured air environment inside the package. Preferably, the low O ₂ -environment has an O ₂ content of 0-5% by volume, more preferably 0-1% by volume. When the indicator is a palladium-containing porphyrin, preferably the low O ₂ -environment has an O ₂ content of 0-5% by volume, more preferably 0-1% by volume. When the indicator is a platinum-containing porphyrin, preferably the low O ₂ -environment has an O ₂ content of 0-0.1% by volume, more preferably 0-0.05% by volume.

Effective shielding to maintain a low O ₂ -environment is a problem with providing packaging with an effective O ₂ barrier layer. Material capable of providing a _{O 2} barrier layer required, 25 ° C., allowed 0% RH, at 1atm oxygen (ASTM D 3985), an oxygen permeability of up to 100cc ^/ m ^2/24 hours (OTR) material It is. Preferably, the oxygen barrier properties of the barrier layer is 25 ° C., 0% RH, at 1atm oxygen, allowing an OTR of maximum 50cc ^/ m ^2/24 hours. More preferably, the oxygen barrier property of the oxygen barrier layer, 25 ° C., 0% RH, at 1atm oxygen, allowing an OTR of maximum 25cc ^/ m ^2/24 hours. Most preferably, the oxygen barrier property of the oxygen barrier layer, 25 ° C., 0% RH, at 1atm oxygen, allowing OTR up 1cc ^/ m ^2/24 hours.

All polymeric materials can provide these penetration rates if their cross-sectional thickness is sufficient. 1 mil thick, 25 ° C., 0% RH, at 1atm oxygen, polyethylene having oxygen permeability of 2000cc ^/ m ^2/24 hours, when the cross-sectional thickness exceeds 20 mils, above, 25 ° C. , 0% RH, to meet the barrier requirements of 100cc ^/ m ^2/24 hours at 1atm oxygen. Materials that can provide oxygen barrier requirements with very thin cross-sectional thickness include polyesters, polyamides, ethylene vinyl alcohol copolymers, polyvinyl alcohol homopolymers, polyvinyl chloride, polyvinylidene chloride homopolymers and copolymers, polyethylene naphthalate , Polyacrylonitrile homopolymers and copolymers, and liquid crystal polymers. Furthermore, the oxygen barrier properties of the polymeric material can be increased by depositing a thin film of carbon, metal, metal oxide, silica and / or silicon oxide, and SiO _x . The barrier properties of the polymeric material can also be enhanced by melt blending the polymer with glass, clay, and / or a polymer having a relatively low oxygen transmission rate (ie, a relatively high oxygen barrier). It can also be increased by blending polymers, metals, metal halides and the like with oxygen scavengers.

  Preferably, the multilayer film has a sealing layer, preferably a sealing layer comprising a heat-sealable material. Suitable examples of encapsulants include ethylene / alpha olefin copolymers, homogeneous ethylene / alpha olefin copolymers, ethylene / vinyl acetate copolymers, ethylene / alkyl acrylate copolymers, ethylene / arlylic acid copolymers, ionomers, propylene homopolymers and copolymers, butylene Polymers and copolymers, multicomponent ethylene / alpha-olefin interpenetrating networks, propylene homopolymer and propylene / ethylene copolymer blends, high density polyethylene, high density polyethylene and ethylene / vinyl acetate copolymer blends, high density polyethylene and low density polyethylene Olefinic polymers such as blends of any of these or blends of any of these materials; polyamides or copolyamides; Other suitable polymeric materials. The sealing layer in the various films disclosed below is arranged as an outer (surface) layer. This layer is generally located closest to the oxygen sensitive product and serves to provide a means for sealing the film itself or a barrier liner or the like (trayed product) during the packaging operation.

A luminescent compound is a compound that strongly absorbs electromagnetic radiation (EMR) at one frequency (excitation frequency) and emits EMR at the same or another frequency (radiation frequency). Luminescent compounds suitable as indicators in the present invention emit light only in the absence of O ₂ . More precisely, the indicators emit light upon exposure to their excitation frequency only when the O ₂ concentration falls below the threshold level. If the O ₂ concentration to which the indicator is exposed exceeds a threshold level, oxygen prevents or “extinguishes” luminescence.

  Porphyrin is a preferred indicator for use in the method of the present invention. Porphyrins include bioactive nitrogen compounds (eg, chlorophyll) that exist widely in nature, and synthetic nitrogen compounds that can be prepared by passing current through a mixture of ammonia, methane and water vapor. The structure of a porphyrin contains four pyrrole rings, together with four nitrogen atoms and two substitutable hydrogens where various metal atoms can be easily replaced. In the preferred porphyrins for use in the method of the invention, platinum or palladium replaces the replaceable hydrogen at the center of the compound. Two preferred porphyrin structures are shown immediately below.

Porphyrin compounds emit phosphorescence in the absence of oxygen (ie, O ₂ ) when irradiated with certain wavelengths of light, particularly long wavelength ultraviolet radiation. This phosphorescence is extinguished by O ₂ which limits the relative brightness or lifetime of the generated phosphorescent light. This light intensity or duration relationship is inversely proportional to the amount of O ₂ present. Platinum, palladium and other metalloporphyrins, however, also function with different sensitivity to different relative levels of oxygen and changes in oxygen concentration.

By appropriate selection of pendants, porphyrins can impart some solubility or dispersibility in different resins and / or inks. A suitable porphyrin can be dissolved or dispersed in the resin that is then introduced into the film layer, or on the surface of the O ₂ -barrier film it can be dissolved or dispersed in the next printed ink. can be, then, O 2 _- barrier film is used to make a package containing a low O ₂ levels in the packaging inside.

  The term “luminescent” as used herein includes any electromagnetic emission that can serve phosphorescence, fluorescence, or indicator function. When the emission frequency is in the visible spectrum, the indicator can be read by the machine or the human eye. When the emission frequency is not visible, the emission may be detected with a machine.

Luminescent compounds suitable for use in the present invention include any known or later discovered compounds having the functionality described herein. Furthermore, suitable luminescent compounds and compositions comprising them preferably further have one or more of the following characteristics:
a) Their response to changes in oxygen concentration is predictable, linear and completely reversible. Linearity is desirable for calibration and quantitative monitoring purposes. Reversibility allows oxygen concentration to be monitored at any stage of the packaging and storage process;
b) They are sensitive to oxygen concentrations within the target range. The range can include 0% to 5% oxygen, such as 0% to 1%, or 0 to 1000 ppm. Combinations of indicators with different ranges and sensitivities may be used to expand such ranges if desired;
c) They respond quickly to changes in oxygen concentration in the conditions in which they are used. The typical response time of luminescent compounds to changes in oxygen concentration is within 1 minute of environmental change over a temperature range of 0 ° C. to 25 ° C .;
d) They emit light over a range of frequencies that are easily monitored. When using an inexpensive check device, the indicator should have a suitable excitation and emission frequency, preferably visible frequency;
e) They are selectively responsive to changes in oxygen concentration and are insensitive to other gases that may penetrate the packaging material containing the dye, such as carbon dioxide;
f) They are stable under the conditions of use and storage. Light stability is desirable but not necessary. Temperature stability and stability against changes in humidity are desirable and preferred;
g) They are transparent or match in color with the packaging in which they are used. Color matching is important, for example, where the indicator may form all or part of the printed image. In embodiments where individual patches are used, transparency or color matching is usually not important;
h) they exhibit good coating and / or printability and / or are extrudable; and i) indicators are useful at relatively low concentrations to minimize the cost of the overall packaging material It is.

  Preferred luminescent compounds for use in the present invention include fluorescent or phosphorescent dyes that exhibit oxygen fire extinction. Phosphorescent dyes are preferred over fluorescent dyes for oxygen sensitivity because they have the characteristic of clearly separating excitation and emission frequencies. These frequencies are generally in the visible region of the spectrum and have a long excited lifetime. Phosphorescent dyes also have improved sensitivity to low levels of oxygen to facilitate monitoring.

  Compounds suitable as indicators in the context of the present invention are known in the art. For example, US Pat. Nos. 4,810,655 and 5,043,286 (Khalil et al.), Incorporated by reference, disclose suitable compounds and methods for their preparation. Such compounds include octaethylporphyrin, tetraphenylporphyrin, tetrabenzoporphyrin, or metallo derivatives of chlorin, bacteriochlorin, or isobacteriochlorin and their partially or fully fluorinated analogs. . Other suitable compounds include palladium coproporphyrin (PdCPP), platinum and palladium octaethylporphyrin (PtOEP, PdOEP), platinum and palladium tetraphenylporphyrin (PtTPP, PdTPP), camphorquinone (CQ), and erythrosine B (EB And xanthine type dyes. Other suitable compounds include ruthenium, osmium and iridium complexes with ligands such as 2,2'-bipyridine, 1,10-phenanthroline, 4,7-diphenyl-1,10-phenanthroline. Suitable examples of these include tris (4,7-diphenyl-1,10-phenanthroline) ruthenium (II) perchlorate, tris (2,2′-bipyridine) ruthenium (II) perchlorate, and tris (1, 10-phenanthroline) ruthenium (II) perchlorate. Perchlorate salts are particularly useful, but other counter ions that do not interfere with light emission may be used.

Alternative oxygen sensitive fluorescent materials include the following:
Rhenium complex-Re (I)
ReL (CO) ₃ NCR ⁺
(Where L = α-diimine, R = aliphatic group) (Analytical Chemistry 1995, 67, 1377-1380, incorporated herein by reference),
Erythrosine B (Analyst, Feb 1995, V120, p457, incorporated herein by reference),
Other porphyrin metals Zn
Lu (Lutetium)
Y
Sn
Pb
Pt
Pd
Hf
(J chem. Soc perkin trans, 2 1995, p103, incorporated herein by reference),
Ruthenium complex Ru (II) (J phys chem, 1995, 99, 3162-3167, incorporated herein by reference),
Ruthenium complex, also known as tris (2,2′-pipyridyl) Ru (II) dichloride, or RuBIPPY (Sensors and Actuators B 29, (1995) 251-257, incorporated herein by reference).

  A composition comprising one or more indicator compounds is preferably dissolved in a polymer carrier or solvent matrix (system). There are two reasons for this. One reason is that the solution achieves utilization of the indicator compound for maximum dispersion and thus maximum efficiency. Another is that aggregation of the indicator compound must be avoided due to the reverse interaction between the two indicator molecules resulting in self-extinguishing and reduced efficiency. It is well known that the polymer matrix affects the emission decay of the indicator (see J. Phys. Chem., 1995, 99, 3162-3167).

  The indicator composition can be selected for maximum solubility in the polymer or solvent system. By varying the ligand substituents, the solubility of the ligand indicator in the polymer or solvent matrix can be altered. For example, to select a porphyrin having the desired solubility in the polymer or solvent matrix, the non-fluorinated porphyrin may be replaced with a partially or fully fluorinated porphyrin, or tetraphenylporphyrin with octaethylporphyrin, etc. it can. Where the complex includes a counterion, the choice of counterion can affect the solubility of the compound in the polymer matrix.

One skilled in the art understands that very small amounts of indicator are required to achieve sufficient luminescence for good detection. The indicator compound is preferably used at a relatively low concentration to minimize the cost of the overall packaging material. A suitable concentration of the indicator compound can be from several μg / in ² (area) to several mg / in ² (area).

  Various embodiments of the present invention are based in part on the selection of the polymer or solvent system and the required concentration for the indicator compound. If the indicator is sufficiently heat stable, it can be effectively dissolved in the polymer and extruded. By adjusting the indicator concentration and the polymer thickness, an appropriate area concentration for observing luminescence can be achieved. In addition, the indicator and polymer system can be extruded in several ways to introduce it into a suitable solid. For example, the indicator can be dispersed in a single layer film or in one or multiple layers of a multilayer film that also includes a barrier layer or coating. Single or multilayer films can be cut to form an applique and bonded to a suitable backing material.

  If the indicator compound is more compatible with a particular solvent, it can be introduced into the solvent and / or ink system and effectively printed on a suitable film or substrate. As part of a suitable ink system, the indicator compound can be trap printed with graphics including an oxygen scavenging film.

To be effective in notifying the presence of a leak in the packaging, porphyrins, O ₂ in the film - is to be located inside the packaging with respect to the position of the barrier layer. In this way, upon irradiation (ie, upon excitation), the porphyrin emits phosphorescence at a level that is inversely proportional to O ₂ in the immediate vicinity. A package with a low internal O ₂ environment will strongly phosphorescent the porphyrin with O ₂ present around any small leak that extinguishes (or dims) the porphyrin phosphorescence in the immediate vicinity of the leak, thereby A leak is signaled by contrasting the absence of phosphorescence around the leak with a high level of phosphorescence at a distance from the leak. Relative phosphorescence is easily identified in the dark room under ultraviolet irradiation (eg, black light). Even relative hue / luminance differences can be easily identified with the use of a blue absorbing lens that further enhances the visual hue contrast.

By scanning this difference in phosphorescence level, small leaks can be identified as they appear as gray dots surrounded by shining areas. Put a very large amount of O ₂ into the package such that the leak is a large leak and the O ₂ level in the package is high enough to extinguish the phosphorylation activity of the porphyrin throughout the entire or substantial portion of the package The scan reveals the absence of this phosphorescence, thereby confirming the presence of one or more substantial leaks in the package.

By using the method of the present invention, even the presence of a small leak in the package can be detected almost immediately if a leak is present. In this way, the package can be tested for the presence of a leak as soon as the package is made, during which time, O 2 _- the sensitive product, is removed from the packaging are leaking, repackaging it And there is still an opportunity to retest this for the presence of one or more leaks. In this way, the number of leaking packages shipped from the packer can be reduced or eliminated.

  Packaging scans for the presence of one or more leaks can be done manually (ie, with the naked eye) or with automated imaging systems (eg, machine images) such as those available from Cognex or DVT. Can be done using. By using either system, packages determined to be leak free can be routed to circulation, and packages determined to be leaked are sent for repackaging. Automated imaging systems can be designed to be more sensitive than human eyes in detecting leaks, and can also be designed to identify the edges and surfaces of packages.

  The machine image uses a machine (eg a computer) combined with some form of image generator (eg a camera), in particular to determine whether a predetermined shape exists in the object being evaluated. To do. With an image generating device that senses the presence or absence of one or more predetermined shapes, the machine communicates with the operating device such that some motion or inactivity occurs. Thus, the operation may or may not occur depending on the content of the image sent from the camera to the computer. Image capture and processing can detect and take into account spatial relationships such as edges, hues, and the like. Machine video is well known, as is evident from educational courses that have been left to the subject. The textbook Image Processing, Analysis and Machine Vision by Sonka, et al., Which is incorporated by reference in its entirety. , Brooks / Cole Publishing, Pacific Grove, CA 1999.

  In the present invention, the oxygen-extinguishing porphyrin-containing layer in the package is irradiated with a wavelength of light that excites the porphyrin in order to cause phosphorescence. Irradiation is performed using the ultraviolet wavelength of UV-A black light, that is, around 360-400 nm. The presence of oxygen in the vicinity of the porphyrin extinguishes this phosphorescence. However, in the absence of oxygen, phosphorescence persists and is therefore visible. Phosphorescence from porphyrin is carmine red visible light at a wavelength around 660 nm.

  Scanning can be done manually using the naked eye. However, if machine image scanning is desired, it can be done with a suitable camera device coupled to a suitable computer. The image captured by the camera has three primary colors: black background, purple (from UV-A bulb) + excited, green light with red of hypoxic porphyrin (also from UV-A bulb) A combination of things that overflowed in small amounts. These colors are captured in each pixel information. Depending on the camera selected and its distance from the product, each pixel has a dimension of a few mils to 1/8 inch depending on the packaging surface.

  A computer (or the naked eye) can easily process images for color and intensity. Colors such as carmine red are easily identified. Visible edges, such as packaging edges, are pixels on one side of the border (eg, black background) and pixels not on the other side of the packaging surface (eg, purple and UV-A bulbs). Easily determined by comparison of green and / or red without oxygen). Within the visible boundaries of the package, the computer observes and compares the areas due to these red (oxygen-free colors) or UV-A black light bulb colors. The computer can be programmed to identify and ignore black individual random pixels on the red field as “noise”, but any extension of black within the visible red border of the packaging. If there is an area, appropriate action can be taken. An expanded area without a red color indicates the presence of oxygen, i.e. the presence of a leak. The computer may program to take action based on the identification of one or more black points in the red field to have the package undergo further inspection and / or transfer for repackaging. it can. In this way, the package is inspected for leaks (and repackaged if a leak is detected) so that the leaking package is not shipped from the packaging location.

  Scanning is performed on some or all of the packaging. If machine image scanning is used, one means of scanning the entire package involves several cameras that simultaneously prepare one or more images that cover the entire surface of the package. Alternatively, a single camera can be combined with several means of scanning the entire package and the package can be rotated while looking at the camera, or the camera can be rotated around the package, and all sides of the package can be Or it can be used to obtain one or more videos covered together.

  Commercially available machine video hardware suitable for conformance to the present invention and supporting software is available from One Vision Drive, Natick, MA 01760-2059 Natick, Cognex Corporation, MA (contact: www. cognex.com or (508) 650-3000). Other sources of information for machine imaging devices are DVT US Headquarters, 1855 Satellite Blvd, Suite 100, Duluth, GA 30097-4061 (contact: www.dvtsensors.com or 770-814-7920) (DVT). Corporation). In addition, there are many companies that can assemble and customize such systems from available hardware and software. Thomas Register 2003 contains a 14-page company list under the heading “Machine Video”.

Automatic scan somewhere film, separately brighten the packaging black background, non-O ₂ - may be aided by the inclusion of suitable amount of a second ultraviolet fluorescent compound is sensitive. Of course, this second ultraviolet fluorescent compound must fluoresce at a frequency different from the phosphorescence frequency of the leak indicator compound. Examples of compounds that can be used as the second ultraviolet fluorescent compound include compounds classified as benzoxazole. A preferred benzoxazole is 2,5-thiophenediylbis (5-t-butyl-1,3-benzoxazole). For example, the compound absorbs short wavelength UV radiation that excites an oxygen sensitive fluorescent compound but emits high frequency light in the green-yellow range. The machine imaging system then determines the difference between the two wavelength emissions to identify the packaging edge that is the boundary between “grey” and “yellow-green”, and then the red emission of the oxygen sensitive fluorescent compound. Can be used to look for the relative intensity of. This further helps to identify the location of the leak along the edge of the package that appears the same as the “gray background” seen separately in the imaging system.

  In scanning multilayer films, optical or digital filters can be used to increase sensitivity to the excited emission wavelength (ie, the wavelength of phosphorescence emitted by the indicator compound). The excited emission wavelength can then be scanned by a raster system such as a television camera or captured as an optical image focused on a suitable array detector such as a CCD (Charge Coupled Device). it can. The captured image can then be analyzed for relative excitation emission intensity. For the appropriate wavelength, the gray area surrounded by the shining area represents leakage because the emission is oxygen extinguished in the immediate area, resulting in a gray area.

  To ensure complete coverage of the finished package, it is necessary to observe all sides. In one embodiment, several fixed light sources and fixed systems are used to fully view all sides of the finished package. Alternatively, a single light source and detector can be moved around the package for complete coverage of all sides. Alternatively, the finished package can be moved around within the field of view of a single fixed light source and fixed detector system to achieve full inspection of all sides.

In one embodiment, the indicator is in the film layer, about ^{0.001mg / m 2 ~20mg / m 2} , preferably, 0.01~2mg / ^{m 2,} more preferably, 0.1 to 1 mg / ^{m 2} More preferably, it is present in an amount of 0.2 to 0.5 mg / m ² . When scanning for leaks with the naked eye, additional indicators can make the machine imager more sensitive to color difference detection than the naked eye, so that machine images are used. Sometimes it is needed.

  The indicator can be blended together with the film layer, or can be printed on the inner surface of the film or between two film layers of a laminated multilayer film. When printed, the indicator is present in the ink composition. Although it is preferred to have an indicator present throughout the package, this need not be the case. For example, it may be preferable to provide an indicator only in areas where leakage often occurs, such as in a sealed area, i.e., an area subject to overuse. Oxygen scavengers can be used in the film as indicated above, but in some cases it is preferred that the film does not contain an oxygen scavenger and indeed the packaging is oxygen scavenger. It is preferable not to contain an agent.

Many “fresh” products, such as meat, can react with air O ₂ . That is, such a product is an effective O ₂ -catalyst. Such a product that collects O ₂ from the inside of the package can reduce the O ₂ concentration inside the package to a level that can be phosphorescent when irradiated with porphyrin.

The film used in the method of the present invention can further comprise an O ₂ -collecting agent in one or more layers inside the O ₂ -barrier layer of the film. The collector will maintain a low O ₂ level inside the package and ensure that the indicator layer will not hinder phosphorescence emission due to the presence of sufficient O ₂ in the package to extinguish the indicator. You can operate both. Furthermore, the presence of a film layer containing an O ₂ -capture agent allows the method of the present invention to be used because the O ₂ collection rate is significantly slower than the ability of O _{2 at} the leak location to extinguish the indicator at that location. It turns out that it does not impair the ability to do. A scavenger can also be present in the layer containing the indicator.

  For details on the structure and use of the indicator, particularly in relation to the use of the indicator in the packaging film, in addition to the detection of phosphorescence from the indicator in the packaging film, in particular in relation to the presence of an oxygen scavenger in the packaging film, see No. 09/875515, entitled “Oxygen Detection System for a Solid Article” (filed Jun. 6, 2001, U.S. Patent Publication No. 2003 / 0082321A1), which is hereby incorporated by reference in its entirety. Issue) was published on May 1, 2003).

  In these cases, the packaging finds the benefit of guaranteeing against the presence of oxygen by including an oxygen scavenger in the packaging within a low oxygen modified air packaging (MAP) or vacuum packaging (VP). . Packaging materials containing oxygen scavengers have recently grown and become increasingly sophisticated. For example, Spare et al. Have developed a transparent multilayer packaging film that introduces an oxygen scavenging composition into the layer. See U.S. Pat. Nos. 5,529,833, 5,350,622 and 5,310,497.

FIG. 1 shows a cross-sectional structure representing a packaged product for use in the method of the present invention. Packaged product 10, _{O 2} - has a sensitive product 12 - _{O 2} surrounded around by a multilayer film 14 including the barrier layer 16, the indicator layer 18 and the sealing layer 20. Although the multilayer film 14 generally surrounds the O ₂ -sensitive product 12, FIG. 1 shows only a portion of the cross section of the film 14. In FIG. 1, the indicator layer 18 is disposed “inside” the O ₂ -barrier layer 16, ie, the indicator layer 18 is relative to the O ₂ -barrier layer 18 on the outer surface 22 of the packaged product 10. It should be noted that it is located further inside. This, O 2 _- barrier layer 18, so prevents the atmospheric O ₂ to extinguish phosphorescence indicator layer 18 is important.

  FIG. 2 illustrates an overview of a preferred method for producing the multilayer film described in Tables I-VIII below. In the method shown in FIG. 2, solid polymer beads (not shown) are fed to a plurality of extruders 30 (for simplicity, only one extruder is shown). Inside the extruder 30, the polymer beads are sent, melted and degassed, and the resulting bubble-free melt is then sent to the die head 32 and extruded through an annular die, 10-30 mils thick. More preferably, the tube 34 is 15-25 mils thick.

  After cooling or quenching by spraying water from the cooling ring 36, the tube 34 is crushed with a pinch roll 38 and then fed through an irradiated cylindrical ceiling 40 surrounded by a shielding 42, where the tube 34 is And irradiated with high-energy electrons (ie, ionizing radiation) from the core transformer accelerator 44. The tubular 34 is guided to the roll 146 through the irradiation cylindrical ceiling 40. Preferably, the tubular 34 is irradiated to a level of about 4.5 MR.

  After irradiation, the irradiated tubular 48 is guided to the nip roll 50 and subsequently the tubular 48 is slightly expanded into trapped bubbles 52. However, in the trapped bubble 52, the tube is not significantly stretched in the machine direction because the surface speed of the nip roll 54 is approximately the same as the nip roll 50. Furthermore, the irradiated tube 48 is inflated enough to prepare a substantially circular tube without significant lateral orientation, ie without stretching.

The slightly expanded, irradiated tube 48 is passed through the vacuum chamber 56 and then sent to the coating die 58. The second tubular film 170 is melt extruded from the coating die 58 and coated onto the slightly swollen irradiated tube 48 to form a two-layer tubular film 62. Second tubular film 60 preferably, O ₂ without through the ionizing radiation - including barrier layers. Further details of the coating process described above are shown in US Pat. No. 4,278,738 (Brax et al.), Which is incorporated herein by reference in its entirety.

  After irradiation and coating, the two-layer tubular film 62 is wound on a take-up roll 64. Thereafter, the take-up roll 64 is removed and mounted as a rewind roll 66 in the second step in the finally desired tubular film manufacturing method. The two-layer tubular film 62 is unwound from the unwind roll 66 and passed over the guide roll 68, and then the two-layer tubular film 62 is passed through a warm water bath tank 70 containing warm water 72. The crushed, irradiated, coated tubular film 62 is warm water 72 (having a temperature of about 210 ° F.) for a holding time of at least about 5 seconds, ie, a period of time to bring the film to the desired temperature for biaxial orientation. Sunk into. Thereafter, the irradiated tubular film 62 is guided to the nip roll 74 and the bubble 76 is blown to stretch the tubular film 62 laterally. Further, while blowing, ie, stretching laterally, the nip roll 78 stretches the tubular film 62 in the machine direction so that the nip roll 78 has a surface speed that is faster than the surface speed of the nip roll 74. As a result of transverse stretching and longitudinal stretching, an irradiated and coated biaxially oriented blown tubular film 80 is produced, which is preferably in a ratio of about 1: 1.5 to 1: 6. Stretched and stretched at a ratio of about 1: 1.5 to 1: 6. More preferably, the stretching and stretching are each performed in a ratio of about 1: 2 to 1: 4. The result is a biaxial orientation of about 1: 2.25 to 1:36, more preferably 1: 4 to 1:16. While the bubble 76 is held between the pinch rolls 74 and 78, the blown tubular film 80 is crushed by the roll 82 and then carried by the nip roll 78 and the transverse guide roll 84, and then on the take-up roll 86. It is rolled up. The idler roll 88 ensures good winding.

  The polymer component used to produce a multilayer film for use in the manufacture of bags, lids, etc., for use in the present invention, is also typically a component of other additives included in such compositions. An appropriate amount may be included. These are anti-blocking agents (such as talc), slip agents (such as fatty acid amides), fillers, pigments and dyes, irradiation stabilizers (including oxidation-resistant agents), fluorescent additives (materials that fluoresce under UV irradiation) And additives known to those skilled in the art of packaging films, such as antistatic agents, elastomers, viscosity modifiers (fluoropolymer processing aids, etc.).

Multilayer films for use in the method of the present invention are preferably irradiated to cause crosslinking and, in addition, corona treated to roughen the surfaces of the films that are bonded together. As can be seen in the method of FIG. 2, the film is made by extruding the quenched and irradiated substrate before additional layers are extrusion coated thereon. Since the indicators (including porphyrin indicators) may be permanently inactivated when subjected to irradiation at a level of 70 kGy, ie the general level of substrate irradiation, the layer containing the porphyrin is preferably , Only in one or more of the layers of the extrusion coating, so that these layers are not irradiated. Preferably, porphyrins, _{O 2} - are contained inside the binding layer of the barrier layer (tie layer).

  In the irradiation method, the film is subjected to energy irradiation treatment such as corona discharge, plasma, flame, ultraviolet ray, X-ray, gamma ray, and beta ray, and high energy electron treatment that causes cross-linking between molecules of the irradiated material. It is done. Irradiation of polymer films is disclosed in US Pat. No. 4,064,296 (Bornstein et al.), Which is incorporated herein by reference in its entirety. Bornstein et al. Disclose the use of ionizing radiation to crosslink polymers present in the film.

  Dose represents radiation unit “RAD”, or 1 MR, together with 1 million RADS, also known as Megarad, also known as “MR”, known to those skilled in the art. Along with 10 kiloGray, reference is made with respect to the radiation unit kiloGray (kGy). Suitable doses of high energy electrons range from about 16 to 166 kGy, more preferably from about 40 to 90 kGy, and even more preferably from 55 to 75 kGy. Preferably, the irradiation is performed with an electron accelerator and the dose is determined by standard dosimetry methods. Other accelerators such as van der graph or resonant transformers may be used. The radiation is not limited to electrons from the accelerator because any ionizing radiation can be used.

  As used herein, the terms “corona treatment” and “corona discharge treatment” refer to subjecting a surface of a thermoplastic material, such as a polyolefin, to corona discharge, ie, a gas such as air in the vicinity near the film surface. By ionization, ionization initiated by a high voltage passing through a nearby electrode is meant to cause oxidation and changes to the film surface, such as surface roughening.

  US Pat. No. 4,120,716 discloses corona treatment of polymeric materials to improve the adhesive properties of polyethylene surfaces by corona treatment to oxidize the polyethylene surface, which is incorporated herein by reference in its entirety. (Bonet) (issued October 17, 1978). US Pat. No. 4,879,430 (Hoffman), which is incorporated herein by reference in its entirety, also describes an inner surface of a fiber to increase meat adhesion for adhesion of meat to protein material. Discloses the use of corona discharge for the treatment of plastic fibers for use in cooking meat in its package with a corona treatment. Corona discharge is a preferred treatment for multilayer films used to make the patch bags of the present invention, but plasma treatment of the film may also be used.

  The multilayer film is preferably used in the method of the present invention by heat sealing a tubular film (i.e., with no back seams or seams) to make an overlaid flat back, which is an end seal bag or a side seal bag. Converted into a bag for. Similarly, the two parts of the flat film can be sealed together to make a U-seal pouch, or the flat film can be folded over itself to make a side seal bag or L-seal bag Can be sealed. One or more patches can be provided on the bag. End seals, side seals, and L-seal bags, and patches thereon, are described in US Pat. No. 6,383,537 B1, named “Patch Bag Having Overhanging, Bonded Patches”, which is incorporated herein by reference in its entirety. Is disclosed.

FIG. 3 shows a barrier film with a tray 118 having an O ₂ -barrier liner film 116 adhered to its inner surface, an O ₂ -sensitive product 111 (such as minced meat) disposed in the tray 118, and a tray flange 113. A cross-sectional view of a portion of a packaged product 117 that includes a multilayer lid film 110 adhered or sealed to 116 is shown. The multi-layer lid film 110 has an outer O ₂ -barrier layer 120 and an inner seal and indicator layer 122. The upper space 124 includes low O ₂ denatured air. The barrier liner film 116 can be single or multilayer in the composition and includes an oxygen barrier layer of the type disclosed herein. Suitable olefinic sealants, including olefinic materials of the type disclosed herein, can form separate layers in the barrier liner. A common five-layer configuration for the barrier liner 116 is an olefin polymer or copolymer / binder / EVOH / binder / olefin polymer or copolymer.

  Table I below provides preferred multilayer film structures for use in the present invention, including the composition, thickness, and general function of each film layer. The film, extruded from an annular die and then extrusion coated, is in the form of a seamless tube, has a total thickness of approximately 2.4 mils, at 185 ° F., 20% in the machine direction and transverse direction Showed a total free shrinkage of 33%.

  In Table I, LLDPE # 1 is DOWLEX® 2045 linear low density polyethylene, obtained from Dow Chemical Company of Midland, Michigan. LLDPE # 2 is ESCORENE® LL3003.32, a linear low density polyethylene, obtained from Exxon Chemical company of Baytown, Texas. SSPE # 1 is an AFFINITY® PL1280 metallocene catalyzed ethylene / octene copolymer having a density of 0.900 g / cc and a melt index of 6 g / 10 min and was obtained from Dow. HDPE # 1 is Fortiflex® T60-500-119 high density polyethylene, obtained from Solvay Polymers, of Deer Park, Texas. EVA # 1 is ESCORENE® LD 318.92 ethylene / vinyl acetate copolymer, having a melt index of 2.0, a density of 0.930 g / cc and a vinyl acetate monomer content of 9%, Exxon Corporation Obtained from EBA # 1 is an SP1802 ethylene / butyl acrylate copolymer containing 18% butyl acrylate and was obtained from Chevron Chemical Company, of Houston, Texas.

  Table II below lists other preferred multilayer film structures for use in the present invention having a total thickness of 3 mils, 185 ° F., and 28% free shrink in the machine direction and 36% in the cross direction. provide.

  Table III below lists other thicknesses for use in the present invention having a total thickness of about 2.2 mils and a free shrinkage of about 31% in the machine direction and about 44% in the transverse direction at 185 ° F. A preferred multilayer film structure is provided.

  Table IV below shows other preferred multilayer films for use in the present invention having a total thickness of 2.3 mils, 185 ° F., 25% in the machine direction and 41% in the transverse direction. Provide structure.

  Table V below shows other preferred multilayer film structures for use in the present invention having a total thickness of 2 mils, 185 ° F., 31% in the machine direction and 46% in the transverse direction. provide.

  Table VI below shows other preferred multilayer films for use in the present invention having a total thickness of 2.2 mils, 185 ° F., 36% in the machine direction and 51% in the transverse direction. Provide structure.

  In Tables II-VI, SSPE1 was a Dow Affinity® PL1280 ethylene / octene copolymer having a density of 0.900 g / cc and a melt index of 6 g / 10 min. SSPE2 was Dow Affinity® PL1850 with a density of 0.902 g / cc and a melt index of 3 g / 10 min. SSCPE3 is a DPF 1150.01 single-site catalyzed ethylene / octene copolymer having a density of 0.901 g / cc and a melt index of 0.9 g / 10 min and was obtained from Dow. LLDPE1 was Exxon ESCORENE® LL3003.32 linear low density polyethylene with a density of 0.9175 g / cc and a melt index of 3.2 g / 10 min. LLDPE2 was Dow Attane® 4203 with a density of 0.905 g / cc and a melt index of 0.8 g / 10 min. LLDPE3 was Dow Dowlex® 2045.03 linear low density polyethylene having a density of 0.92 g / cc and a melt index of 1.1 g / 10 min. LLDPE4 was an Exceed® 4518 PA ethylene / hexene copolymer with a density of 0.918 g / cc and a melt index of 4.5 g / 10 min. LDPE is a Ruxell® V3401 ethylene / octene copolymer having a density of 0.911 g / cc and a melt index of 5.7-7.5 g / 10 min and was obtained from Huntsman. EVA1 is an LD-713.93 ethylene / vinyl acetate copolymer with a vinyl acetate content of 15%, a density of 0.933 g / cc and a melt index of 3.5 g / 10 min, obtained from Exxon. . EVA2 is an Escorene® LD761.36 ethylene / vinyl acetate copolymer having a density of 0.95 g / cc, a melt index of 5.7 g / 10 min, and a vinyl acetate content of 28%, ExxonMobil From ExxonMobil. EVA3 is an Escorene® LD 318.92 ethylene / vinyl acetate copolymer with a density of 0.93 g / cc, a melt index of 2 g / 10 min, and a vinyl acetate content of 9%, from ExxonMobil obtained. EVA4 is an Elvax® 3128 ethylene / vinyl acetate copolymer having a density of 0.928 g / cc, a melt index of 2 g / 10 min, and a vinyl acetate content of 8.9% and is manufactured by DuPont (DuPont). ). EMA is an EMAC SP 1305 ethylene / methyl acrylate copolymer with a 20% methyl acrylate content, a density of 0.944 g / cc and a melt index of 2 g / 10 min, obtained from Exxon. EPD is a Vistalon® 7800 ethylene / propylene / diene terpolymer having a density of 0.87 g / cc and a melt index of 1.5 g / 10 min, obtained from Exxon. VDC / MA is a SARAN® MA-134 vinylidene chloride / methyl acrylate copolymer, obtained from Dow. Epoxidized soybean oil is PLAS-CHEK® 775 epoxidized soybean oil and was obtained from Bedford Chemical Division of Ferro Corporation, of Walton Hills, Ohio. The bu-A / MA / bu-MA terpolymer is a METABLEN® L-1000 butyl acrylate / methyl methacrylate / butyl methacrylate terpolymer and is available from Elf Corporation (Elf Atochem North America, Inc., of 2000 Market Street, From Philadelphia, Pennsylvania 19103). MB1 is an FSU 93E polyethylene masterbatch with slip agent and antiblocking agent having a density of 0.975 g / cc and a melt index of 7.5 g / 10 min, obtained from A. Schulman . MB2 is a 180637 light cream masterbatch with a density of 1.25 g / cc and was obtained from Ampacet.

  In the films of Tables I-VI above, the layer identified as the “indicator” layer is the preferred layer for blending the indicator with the polymer that makes up the particular layer. Of course, this is not the only layer that can be used as an indicator layer. Further, the indicator can be printed on either the inner surface of the film or on the irradiated substrate prior to extrusion coating, for example, so that the print is captured between the layers of the multilayer film.

Other films useful in the method of the present invention are multilayer films such as Cryovac Inc. for packaging of fluids or pumpable foods in pouches made in vertical forming / filling / sealing devices. FS (trademark) film. This type of film has a general structure:
Encapsulant / binder / nylon / EVOH / nylon / binder / encapsulant (wherein the encapsulant includes any disclosed herein and the binder layer is anhydrous) A modified polymer olefinic or amide based adhesive, the nylon layer comprising any polyamide or copolyamide and the EVOH (ethylene / vinyl alcohol copolymer) layer functioning as an oxygen barrier layer). The oxygen scavenger can be suitably included as a layer within the film structure described above, and the oxygen indicator can be present in any one or more layers inside the EVOH layer, or of the barrier layer. It can be printed on any of the aforementioned interlayers inside the EVOH layer or on the encapsulant layer of the film.

  Although the present invention has been described in connection with the preferred embodiments, it will be understood that modifications and variations may be utilized without departing from the principles and scope of the invention, as will be readily appreciated by those skilled in the art. Should be. Accordingly, such modifications are possible within the scope of the claims.

FIG. 2 schematically shows a bag-type packaged product for use in the method of the present invention, the package comprising an O ₂ -sensitive product surrounded by a multilayer film, part of which is illustrated in a cross-sectional view. It is a figure which shows the outline of the manufacturing method of the film for use in this invention. FIG. ₂ is a cross-sectional view of a tray-type package product for use in the present invention, where the package includes an O ₂ -sensitive product on which a multilayer film lid film is present.

Claims (29)

(A) (i) A leak indicator in which the O ₂ -sensitive indicator is present throughout the leak indicator layer
Layer, and (ii) the leak indicator layer outside of O ₂ - in the multilayer film comprising a barrier layer, O 2 _- preparing a package by covering at least part of the sensitive products,
(B) providing a low O ₂ environment in the package;
(C) the leak indicator layer, said with the O ₂ - irradiation with light having a wavelength that is absorbed by the sensitive indicator, thereby O ₂ - sensitive indicator, O 2 _- of the O ₂ present with sensitive indicator Emitting radiation in an amount inversely proportional to the level;
(D) While the O ₂ -sensitive indicator emits radiation, the multilayer film is scanned, and the scanning senses and compares the radiation dose emitted from at least two different areas of the multilayer film. A method for detecting leakage in a package, comprising: Low O ₂ environment
(I) O 2 _- by providing the packaging with scavenger, to collect the packaging inner O _2,
(Ii) exhausting air from within the package; and (iii) replacing atmospheric O _{2 in the} package;
The method of claim 1, wherein the method is provided by performing at least one act selected from the group consisting of:   The method of claim 1, wherein the results of sensing and comparing radiation emitted from at least two different scanning regions correlate with the absence of leakage in the package.   The method of claim 1, wherein the results of sensing and comparing radiation emitted from at least two different scanning regions correlate with the presence of at least one leak in the package. O ₂ of the packaging in which at least one leak - sensitive product, is removed from the packaging, is repackaged by the new packaging method of claim 4.   The method of claim 4, wherein the leak comprises at least one hole in the multilayer film.   The method of claim 4, wherein the leak comprises at least one discontinuity of the seal to the film itself or other components of the package.   The method of claim 7, wherein the seal is a heat seal. The method of claim 1, wherein sensing and comparing are performed such that both the presence and location of atmospheric O ₂ leakage into the at least one package can be determined. Packaging, O ₂ in the bag made by sealing the multilayer film to itself - housing a sensitive product, and then the air is discharged from the inner bag, while discharging the air from the bag, the bag A method according to claim 1 made by sealing the inner layer of the bag to itself across the open tip of the bag.   After the multilayer film has at least 5% free shrinkage at 185 ° F. in both the machine direction and the transverse direction, after the inner layer of the bag is sealed to itself across the opening tip of the bag The method of claim 10, further comprising heat shrinking the film.   The method of claim 11, wherein the product comprises meat. The method of claim 1, wherein the O ₂ -sensitive product is a non-food product.   The method of claim 1, wherein the packaging comprises a bottom forming portion and a lid stock sealed to the bottom forming portion, the lid stock comprising a multilayer film.   The method of claim 14, wherein the packaging comprises denatured air. The method of claim 1, wherein the O ₂ -sensitive indicator is printed on a film. The method of claim 1, wherein the O ₂ -sensitive product collects O ₂ inside the package. The method of claim 17, wherein the O ₂ -sensitive product comprises a food product. The packaging includes a tray with an O ₂ barrier liner, the tray has a flange, an O ₂ -sensitive product is present on the tray, a multilayer film is present over the product, and The method of claim 1, wherein the method is adhered to a tray flange. O ₂ barrier layer, 25 ° C., 0% RH, in 1atm (ASTM D 3985), has a 100cc ^/ m ^2/24 hours or less of oxygen transmission rate, the _{O 2} barrier layer, polyester, polyamide, ethylene vinyl From the group consisting of alcohol copolymers, polyvinyl alcohol homopolymers, polyvinyl chloride, homopolymers and copolymers of polyvinylidene chloride, polyethylene naphthalate, polyacrylonitrile homopolymers and copolymers, liquid crystal polymers, SiO _x , carbon, metals, and metal oxides The method of claim 1, comprising at least one material selected. O 2 _- sensitive indicator comprises octaethylporphyrin, tetraphenylporphyrin, tetrabenzoporphyrin, or chlorins, bacteriochlorins, or at least one material selected from the group consisting of metallo derivatives of the iso-bacteriochlorins, claim The method according to 1. O 2 _- sensitive indicator comprises a porphyrin, a method according to claim 1.   The method of claim 1, wherein the film surrounds the food product.   The method of claim 1, wherein the atmosphere is vented between the food and the film. The method of claim 1, wherein an atmosphere exists between the food and the multilayer film, and the atmosphere comprises O ₂ in an amount less than 5% by weight. Film
i) an oxidizable organic compound and a transition metal catalyst,
ii) ethylenically unsaturated hydrocarbons and transition metal catalysts,
iii) a reduced form of a quinone, a photoreducible dye, or a carbonyl compound having absorption in the UV spectrum,
iv) a polymer backbone, a cyclic olefinic pendant, and a polymer having a linking group that connects the olefinic pendant to the polymer backbone;
v) a copolymer of ethylene and distorted cyclic alkylene, and vi) an ethylene / vinyl aralkyl copolymer,
vii) ascorbate,
viii) isoascorbate,
ix) sulfite,
x) ascorbate and a transition metal catalyst (wherein the catalyst comprises a single metal or salt of a transition metal or a compound, complex or chelate),
xi) transition metal complexes or chelates of polycarboxylic acids, salicylic acids, or polyamines,
The method of claim 1, further comprising an O ₂ -catalyst comprising xii) tannin, and xiii) at least one material selected from the group consisting of reduced metals.   27. The method of claim 26, wherein the oxygen indicator and oxygen scavenger are present in the form of a blend.   28. The method of claim 27, wherein the blend is present in one layer of the film.   The method of claim 1, wherein the oxygen indicator is encapsulated with an adhesive.

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