MXPA97008748A - A method and apparatus to manufacture an exfolia film - Google Patents

Abstract

The present invention relates to: A method for making an exfoliating film comprises providing a multiple layer film, exfoliating the film in a first portion and a second portion, treating the second portion to increase its gas permeability, and relaying the second portion. portion towards the first portion. In another aspect of the invention, an apparatus for making an exfoliating film comprises a means for exfoliating a film in a portion and a second portion, a means for treating the second portion for increasing its gas permeability, and a means for relaying the second portion. portion treated towards the first portion. Perforations, partial perforations and other film treatments can be made, and thus are advantageously used in connection with a second gas-permeable portion preferably of an exfoliating film without affecting a first gas-impermeable portion preferably of the same film.

Description

A METHOD AND APPARATUS TO MANUFACTURE ONE EXFOLIABLE FILM The present invention relates generally to films and sheets, especially for packaging applications such as packaging of fresh red meat or other foods or non-food products. Particularly this invention is directed to the packaging of food products, in such a way that the packaged product can be kept in a condition under certain circumstances and then become another condition. Specifically, packages according to the present invention are provided for the distribution of a product packaged in a medium low in oxygen, and for the introduction of oxygen to the surface of the product in a supermarket or other retail market. This introduction of oxygen is achieved both by the infiltration of oxygen through a film in contact with the surface of the product or through an exchange of atmospheric oxygen with a gaseous atmosphere low in oxygen contained around the product.

While a wide variety of food products can be packaged in accordance with the teachings of this invention, it is particularly advantageous in connection with fresh red meat packing, in such a way that the meat can be transported in a low oxygen atmosphere. say, preferably 0.5% 02 or less, more preferably 0.05% O2 or less, and then cause it to bloom as a bright red color when it is displayed as a market pack by exposure to oxygen.

Historically, large muscles (sub-primary or basic cuts) of meat are cut and packed in each supermarket. However, this may be insufficient and causes certain undesirable additional costs. For examples, all the cuts of the big ones. Muscles should be sold immediately. Instead, it would be better to allow the meat to be cut and packaged in a central facility that would benefit from economies of scale and then be sent to individual supermarkets, such as what is done with many poultry products.

In the past, the goal of central processing of fresh red meat has not been achieved because most consumers prefer to buy meat that has been reddened as a result of oxygen exposure. However, the flesh keeps its color flushed for one or three days only, and then turns into a brown color that is unpleasant to most consumers. Therefore, if the meat was cut and packed in a permeable gas film (sometimes referred to in the future as "permeable") as is typical in the retail market, in a central location and then sent to another location for its final sale, in all instances, by the time the package reaches the retail market, the meat will have undergone the transformation to brown and truly would be unsaleable.

Another problem that is associated with the use of a medium high in oxygen is that the package must contain a certain amount of atmosphere (high in oxygen), resulting in a tray that is only partially filled.

An alternative would be to cut and pack meat in a central location on a gas-impermeable film (sometimes referred to in the future as "waterproof") either under vacuum or vacuum and low oxygen gas irrigation, and then send the packing under refrigeration conditions (28 ° F to 45 ° F) to another location for final sale. The packaged meat would reach the retail market with a purple color that is typical of meat before exposing it to oxygen. Although this fresh purple flesh is very fresh, it has been shown that market efforts have proved difficult to prove to the consumer that the purple color is harmless have been difficult. In addition, if the gas impermeable film was a component of a conventional package having a tray that is overwrapped or covered with a film, and that it contains a low oxygen atmosphere (which would be suitable in this type of package), the waterproof film would have to be peeled off at the retail market and replaced with a permeable film in order to allow the meat to obtain a bright red color before being displayed to the consumer. Certainly this package would widely deny the benefits of a d < = central processing.

A variety of packages have been developed in an effort to provide a means of transporting meat in a low medium with oxygen and to introduce oxygen to the meat quickly and easily in a retail market immediately before displaying it to the consumer.

One approach to solving this problem has involved the development of exfoliating films. That is, films have been developed that quickly exfoliate into permeable or impermeable portions. This type of film is sealed to a support member, such as a tray containing the meat product, and thereby a gas impermeable package is formed for distribution. In the retail market, impervious portions of gas are exfoliated from the film leaving a permeable film sealed to the tray, and consequently a gas permeable package that allows the flesh to bloom a bright red color due to the exchange with oxygen atmospheric. An example of this approach is disclosed in U.S. Patent Application Serial No. 08 / 531,355 (Kocher et al.), Filed on September 20, 1995, entitled "Package with Shrink Film Lidstock", assigned to a common assignee with the present application and incorporated by reference herein in its entirety. A counterpart of the application of USSN 08/531, 355 has been published as European Patent Application EP 071899 Al, published on July 17, 1996, and incorporated by reference herein in its entirety. The peelable film can be spread on top of the contained product and can be sealed to the periphery of the tray as a lid, or the film can be heated and wrapped on the product under vacuum to form a vacuum package.

Other exfoliating films include those disclosed in U.S. Patent Nos. 4,886,690 (Davis et al.) And 4,724,185 (SHAH), both assigned to an assignee in common with the present application and incorporated by reference herein throughout. its entirety Another example of an exfoliating material is disclosed in U.S. Patent No. 4,055,672 (Hirsch et al.).

However, a problem associated with these types of packages is that of the relatively low gas (especially oxygen) transmission rate of the permeable film portion after removing the impermeable portion. permeable of the exfoliating film has a much higher gas transmission rate (typically 5.00 to 25,000 cc / m2 / 24 hrs / atm to 73 ° F) than that of the complete film before exfoliation (typically 0 at 50 cc / m2 / 24 hrs / atm a73 ° F), the proportion of the transmission of the permeable film portion is still too low to cause a rapid flowering of the meat packed in a low oxygen gas atmosphere , except in areas of intimate contact between the permeable film and the meat.Thus, the seller is often in the need to wait for a relatively long period of time for the flowers to flourish. etes exfoliated or displaying the packages that after the beginning of the exhibition still have for some time an unpleasant purple flesh color.

Most other attempts to achieve the goal of central processing of fresh red meat have involved the development of a variety of dual network packages of the type that has a permeable film that covers the product of the meat and a waterproof film, the which is removed in the retail market and which covers the permeable film, wherein the permeable film and the impermeable film are discrete, discrete films. Examples of these are US Patents. Nos. 4,840,271 (Garwood) and 5,348,752 (Gorlich).

Examples of these types of packages include dual overwrap packages, wherein a permeable film is wrapped around the meat and its supporting member and an impermeable film is wrapped around the permeable film; dual lid gaskets including a permeable lid and a waterproof lid sealed to the periphery of the support member; and gaskets with a space permitting the introduction of a treatment gas, typically nitrogen, carbon dioxide or some mixture of the two between a permeable film adjacent to the meat product and a superior waterproof network. However, as is the case with the exfoliable films discussed above, each of these dual network packages limits the permeability of the permeable film. The typical gas transmission ratios for commercially available gas permeable films are from 5,000 to 25,000 cc / m2 / 24 hrs. / atm. at 73 ° F. This is usually too low to cause the rapid flowering of red meat by exchanging low oxygen gas and / or external gases through the film on the outside of the medium, and the indoor atmospheric oxygen at through the film in the inner package. These packages also require two steps of individual sealing in the perimeter of each network.

A development for additional packaging to allow central processing of fresh red meat includes a gas-impermeable top lid with a valve defined in the lid. The package may include a treatment gas between the packed meat and the top cover during dispensing, which is removed through the valve and replaced with an oxygen-rich gas. Although rapid flowering can occur with this system, it also has the disadvantages of iring employees trained in the retail market and relatively expensive equipment to exchange each package and thereby nullify the cost savings of a central processing facility. The presence of the valve also has the disadvantage of giving the package an appearance that is different from that which the consumer is accustomed to seeing in the meat package. In addition, a gas space between the meat product and the waterproof film is ired to maintain the burgeoning color that produces a packaging appearance that is not completely full.

Also another package developed to allow the central processing of fresh red meat is provided for a gas exchange and a rapid introduction of oxygen in which a waterproof upper network covers a permeable lower network, which includes areas not sealed in the seal of. the permeable network with the tray. However, intermittent sealing and unsealed areas are formed by an altered seal head comprising a series of sealing "fingers" in place of a conventional continuous sealing surface. However, this type of packaging presents the possibility of leakage of the purge of the unsealed portions of the seal. Likewise, the purge or moisture that results from condensation in the package can unpleasantly cause blocking of unsealed areas. Additionally, it is difficult to produce this package consistently.

It is therefore desirable to provide a package that allows the central processing of fresh red meat with the minimum processing ired in the retail market, which is similar in appearance - which consumers are accustomed to seeing in the packaging of the meat; which allows a rapid flowering of fresh red meat, and what can be assembled, filled and sealed in a central processing facility over conventional equipment.

One proposed solution is to provide perforations on the permeable portion of a multilayer film or lid in order to increase the full permeability of the permeable portion of the film. An example of this approach is found in U.S. Patent Application Serial No. 08 / 471,065 (Stockley et al.), Entitled "Dual Web Package Having Improsed Gaseous Exchange", assigned to a common transferee with the present application and incorporated by reference herein in its entirety. This would increase the rate of gas exchange from the interior of the package to the exterior medium and from the exterior medium to the interior of the package.

One problem that arises with this approach is the difficulty of partially perforating a multilayer film, such that the impermeable portion remains unaffected in the first part of the packaging cycle (pre-sale) and the permeable portion includes perforations. after the exfoliation. This is a technical challenge to consistently drill a thin film to achieve this criterion. Clearly the perforations can not be through perforations, because this would nullify the objective of providing a package with extended shelving life, since oxygen would quickly enter the package. The practitioner can use dual networks in which one of the nets are drilled but this ires the use of two nets to form the lid of the package.

SUMMARY OF THE INVENTION The inventor found that perforations, partial perforations and other film treatments can be advantageously used in connection with the permeable portion of an exfoliating film without affecting an impermeable portion of the same film.

In an aspect of the invention, a method for manufacturing an exfoliable film comprises providing a multilayer film; the exfoliation of the film in a first portion and a second portion; the treatment of the second portion to increase its gas permeability; and relaying the second portion treated with the first portion.

In another aspect of the invention, an apparatus for manufacturing an exfoliating film comprising a means for exfoliating a film in a first portion and in a second portion; a means for treating the second portion to increase its gas permeability; and a means for relaying the second portion treated with the first portion.

Definitions As used herein, the term "film" refers to a thermoplastic material, generally in sheet or network form, that has more than one layer of polymeric or other materials that can be joined together by any suitable means well known in the art, for example, coextrusion, extrusion lamination, extrusion coating, conventional lamination, etc. The film is considered to be preferably less than 20 thousandths of thickness, more preferably less than 15 thousandths of thickness, so that it is less than 12 thousandths, 10 thousandths, 8 thousandths, 6 thousandths, 5 thousandths, 4 thousandths, 3 thousandths, 2 thousandths and 1 thousandth of thickness.

As used herein, the term "layer" refers to a discrete component of film that is coextensive with the film and has a substantially uniform composition.

As previously used herein, the phrase "gas permeable" refers to a film or a portion of film that admits at least 1,000 cc (cubic centimeters) of gas, such as oxygen, per square meter of film per period of 24 hours at 1 atmosphere and at a temperature of 73 ° F. More preferably, a film or gas permeable film portion that admits at least 5,000, more preferably at least 10,000, at least 15,000, 20,000, 25,000, 30,000, 35,000, 40,000, and 50,000, and more preferably from when less 100,000 cc of oxygen per square meter for a period of 24 hours at 1 atmosphere and at a temperature of 73 ° F. Typical gas transmission rates for films and permeable film portions according to the present invention vary from 1,000 to 100,000, preferably 5,000 to 95,000, such as 10,000 to 90,000, 15,000 to 85,000, 20,000 to 80,000, 25,000 to 75,000. , 30,000 to 70,000 and 40,000 ha. This 60,000 ce of oxygen per square meter over a period of 24 hours at 1 atmosphere and at a temperature of 73 ° F.

As used herein, the phrase "gas impervious" refers to a film or portion of film that admits less than 1000 ce of gas, such as oxygen, per square meter of film during a 24-hour period to 1 atmosphere and at a temperature of 73 ° F. More preferably, a film substantially impermeable to gas admits less than about 500, such as less than 300 and less than 100 cc of gas, more preferably even when it is less than about 50 cc, and more preferably less than 25 cc, such as less than 20 cc. , less than 15, less than 10, less than 5 and less than 1 ce of gas per square meter for a period of 24 hours at 1 atmosphere and at a temperature of 73 ° F.

Oxygen transmission values are determined in accordance with ASTM D-3985.

As used herein, the phrase "product support member" refers to a component of a package on or in which a product is placed. The meat products are typically placed in a tray-like packaging component comprising, for example, a polystyrene sheet material that has been thermally formed into a desired shape, to support the meat product. A product support member preferably includes a cavity in which the product is placed and a peripheral flange that provides a sealing surface for attaching the cap to the support member and thereby enclosing the product within the cavity.

As used herein, the term "joining force" and the like, generally refers to the strength with which two adjacent films or portions of films, or two layers of adjacent films, are connected. The binding force is measured by the force required to separate two films or portions of films or layers of films that are connected.

As used herein, the phrase "preferably exfoliated" and the like refers to the tendency of a multilayer film to exfoliate towards a predetermined layer / layer interface, and / or within a layer, of a of the movies or the portions of the films at the time of exfoliation. Preferential exfoliation is controlled by factors such as, for example, the structure and chemical nature of the film and the manner in which portions of the film or layers are joined.

As used herein, the terms "exfoliate", "exfoliate" and the like refer to the act of removing or separating one or more portions of film or layers from the multilayer film by mechanically or manually compressing and removing a portion of the film. film or layer or layers along a plane or interface of relatively low adhesion strength, or within a portion of film or layer having a cohesion within the relatively weak layer.

As used herein, the term "exfoliation force" refers to the amount of force, in pounds per inch, that is required to separate the two film portions or layers of a multiple layer film, and is measured in accordance with ASTM F904-91.

As used herein, the phrase "sealing film" refers to a film that is bonded in accordance with at least one of the outer surfaces of a product support member. Preferably, the sealing film is attached to the upper part as opposed to the lower outer surface of the support member, and more preferably is attached to a peripheral upper flange of the support member. Preferably, the sealing film is a film substantially impervious to gas.

As used herein, the phrase "ethylene / alpha-olefin copolymer" designates copolymers of ethylene with one or more comonomers selected from 1 to 20 carbon atoms of alpha-olefins, such as butane-1, pentane-1 , hexene-1, octane-1, methyl pentane and the like, wherein the polymer molecules comprise long chains with relatively few branches of side chains. These polymers are obtained by low pressure polymerization processes and the lateral branching present will be small compared to non-linear polyethylenes (e.g., LDPE, a low density polyethylene homopolymer). The ethylene / alpha-olefin copolymers generally have a density in the approximate range of - • to 0.86 gr./cc to approximately 0.94 g./cc. The term linear low density polyethylene. (LLDPE) is generally understood to include the group of ethylene / alpha-olefin copolymers falling within the density range from about 0.915 to about 0.94 gr./cc. Sometimes linear polyethylene in the density range of about 0.926 to about 0.94 is referred to as a linear density medium polyethylene (LMDPE). Ethylene / alpha-olefin low density copolymers can be referred to as very low density polyethylenes (VLDPE, typically used to refer to the • ethylene / butane copolymers that are available in the Union Carbide with a density in the range of about 0.88 to about 0.91 g / cc) and ultra-low density polyethylene (ULDPE, typically used to refer to the copolymers of ethylene / octane supplied by Dow).

The phrase "ethylene / alpha-olefin copolymer" also includes homogeneous polymers, such as homogeneous linear copolymer resins of metallocene catalyzed EXACT ™ obtainable from Exxon Chemical Company, of Baytown, Texas; Ethylene / alpha-olefin homogeneous linear copolymer resins from TAFMER ™ available from Mitsui Petrochemical Corporation; and homogeneous ethylene / alpha-olefin catalyzed long chain branch metallocene copolymers obtainable from The Dow Chemical Company, known as AFFINITY ™ resins. The phrase "homogeneous polymer" refers to polymerization reaction products of relatively narrow molecular weight distribution and relatively narrow composition distribution. The homogeneous polymers exhibit a relatively even sequence of the comonomers within a chain, a mirage of sequence distribution in all chains, and a length-of-all-chains, ie, a narrower molecular weight distribution. In addition, homogeneous polymers are typically prepared by using metallocene and other single site type catalysts instead of using Ziegler-Natta catalysts. These single site catalysts typically have a single type of catalytic site, which is believed to be the basis for the homogeneity of the polymers resulting from the polymerization.

Brief Description of the Drawings Next, a detailed description of the preferred embodiments of the invention, with reference to the accompanying drawings, wherein: Figure 1 is a schematic view of the process and apparatus of the invention; Figure 2 is a perspective view of a package that can be made using the invention; Y, Figures 3, 4 and 5 are partial cross-sectional views of a multilayer film partially exfoliated in accordance with the different embodiments of the invention.

Detailed Description of the Preferred Modalities The present invention is useful in the production of a multilayer film that can be used as a component in a tray type package suitable for the central processing of fresh red meat that includes a member or support tray of the gas impermeable product.; a first portion of gas impermeable film and a second portion of film sealed to the tray, which includes a means defined therein to provide gas exchange inside and outside the package.

More preferably, the package contains a gaseous atmosphere low in oxygen, such as, for example, a mixture of nitrogen / carbon dioxide. In this way the detachment of the portion of the impermeable film allows a release of the low oxygen atmosphere and the introduction of oxygen to the packaged meat product.

The means for gas exchange that is defined within the second portion of the film may be perforations that are exposed at the time of the release of the first portion of the impermeable film; a portion of the highly permeable film that provides an exceptionally high gas transmission area during the release of the first portion of the impermeable film; or partial perforations ("blind holes") that increase the proportion of oxygen transmission of the second portion of the film.

Figure 1 shows an apparatus comprising a means 1 for exfoliating a film 26 preferably co-extruded into a first portion 28 and a second portion 30; a means 2 for the treatment of the second portion 28 to increase the permeability of the gas; and a means 4 for relaying the second portion 30 treated to the first portion 28.

The means 1 for the exfoliation of a film can include any device or process suitable for exfoliating the film 26, such as a manual exfoliation, a mechanical exfoliation device, adhesive tape or the like. The film will preferably be exfoliated in a relatively weak layer / layer interface, and / or within a predetermined layer of a multiple layer film. In the case of a weak layer / layer interface, such as for example a polymeric adhesive interface / EVOH, where EVOH is ethylene / vinyl alcohol copolymer, and the polymer adhesive is preferably a modified anhydride polyolefin.

Another example of this interface is a polyamide / polymeric adhesive interface, wherein the polyamide is preferably nylon 6.12 copolymer, nylon 6.66 copolymer, or a mixture of them, and the polymeric adhesive is of preferably a modified anhydride polyolefin.

The film 26 can be made by a suitable process, such as coextrusion, extrusion cover, lamination of extrusion or conventional lamination, although the film that is co-extruded is preferred. The movie examples Suitable for exfoliation are those "disclosed in European Patent Application EP 0721899 Al.

An example of a multiple layer structure A / B / C / D / C / B / A having a formula is generally as follows: 25PEI 80PA2 90 OB 80PA2 25PEI + / AD / + / + / + / AD / + 75PE2 20PA1 10 PA1 20PA1 75PE2 where: "1 PE1 = LMDPE, an octane-1 ethylene / copolymer with a density of 0.935 gm / cc and an octane-1 comonomer content of 2.5%, available from Dow as Dowlex ™ 2037, PE2 = ethylene / octane-1 copolymer with a density of 0.920 gm / cc and octane-1 content of 6% by weight, available from Dow as Dowlex ™ 2045, AD = polyolefin of anhydride grafted in ethylene-butane copolymer, available from DuPont as Bynel ™ CXA 4104, OB = ethylene / vinyl alcohol copolymer (ethylene of 44 mol%) available in EVALCA as E-151, PA1 = nylon 6.12 copolymer, available from EMS as Grilon ™ CF6S and, PA2 = Nylon copolymer of 6, 66, available from BASF as Ultramid ™ C-35.

Another example of a film suitable for exfoliation is that disclosed in U.S. Patent No. 4,724,185, and discloses a multiple layer structure A / B / C / B / A having a formula that it is generally as follows: polyolefin / adhesive / EVOH / adhesive / polyolefin wherein the polyolefin is a mixture of LLDPE, LMDPE and EVA (ethylene / vinyl acetate copolymer) and the adhesive is a polyolefin of anhydride grafting.

The means two for treating the second portion 28 can include any process or device suitable for the treatment of the second portion 28 to increase its gas permeability, including perforation or partial perforation by means of any suitable mechanism such as laser, electrostatic (spark) electrical) / flame, needle, or sharp particles, as shown in U.S. Patent Nos. 5,257,923 (Kagawa) and 5,352,108 (Kagawa et al.).

The perforations preferably range from about 5 to about 250 microns in diameter, more preferably from 25 to 125 microns, and more preferably from 75 to 100 microns in diameter. Ideally, the perforations are large enough to allow the passage of atmospheric gas through it (oxygen, nitrogen, carbon dioxide), but small enough to prevent the passage of liquids, dust or microbes. The perforations can be formed by any suitable means, including the use of mechanical / chemical or electrical devices. Unlimited examples of these devices include those that drill with a laser, electrostatic discharge, ultrasonic waves, flame discharge, a needle or combinations thereof. An electrostatic device employs electrostatic discharge and passing the second portion of the film 30 between a pair of electrodes, and transmitting electricity to one of the electrodes with sufficient voltage so that the electrode is discharged through the second portion of the peiiculus and toward the other electrode; with this the film is perforated.

The means 4 for re-rolling the second treated portion 30 towards the first portion 28 may include any suitable process or device, such as reheated rolls 4, pressure or both. Whichever means is used, the first and second portions must be re-rolled in such a way that they adhere to each other with sufficient adhesion to keep the two portions together during the production of a film package. , and also provide an exfoliable interface, which defines a relatively low adhesion resistance plane or interface) compared to the film remnant) between the two portions when the first portion is to be peeled off, as described in an additional detail. then. It is within the scope of the invention to relaminate the two portions by simply placing the second portion treated in such a manner as to make contact with the first portion. However, this is less preferred, there is already the possibility that the two portions become separated from one another during the packing cycle and a wrinkling or other unpleasant appearance in the finished package is caused.

In an alternative embodiment, the peelable interface of the re-rolled film may differ from the predetermined layer / layer interface of the multiple layer film in which the film was originally peeled, treated and re-rolled. Thus, the film can be exfoliated in an exfoliating interface, treated to increase the gas permeability in a second portion of film, re-rolled in the same interface, used to build a package and subsequently exfoliated in a different exfoliating interface. An example of this is described herein with respect to the embodiment of Figures 4 and 5.

The medium 3 is shown as an alternative or auxiliary reaming medium, and may include corona treatment or adhesive application or both, in either or both of portions 28 and 30. As shown in Figure 1, the surface interior of portion 28 is treated with crown. The treatment with crowns, dyes or both can be used alone or in conjunction with the heat and / or pressure means, as provided by the press rolls 4. These press rolls 4 are preferably reheated, and preferably exert pressure on the portions 28 and 30.

In this way, any of the aforementioned means, corona treatment, adhesives, heat and pressure, can be used alone or in any suitable combination to re-laminate the first and second portions of the film together.

Example 1 A seven-layer film as described in "European Patent Application EP 0721899 Al was exfoliated by applying Scoth® adhesive tape to the two outer surfaces of the film, and breaking the film into a polymeric adhesive interface / polyamide in a first impervious portion and a second permeable portion, then processed along the upper and lower rollers, the second permeable portion was micro-perforated by means of electric spark media, then the two portions were reflowed by a treatment of corona on a surface of each portion just before reattaching the first and second portions with a crown, treating a surface of each portion just before reassembling the first and second portions with their respective treated surfaces in contact with each , under pressure of the press rolls reheated.

The single network film that is now re-rolled with the micro-perforated permeable portion was sealed along the perimeter flange of barrier foam trays on a Ross 3180 machine at a temperature of 255 ° F, at 80 psi (pound per square inch), for 1.0 seconds. The packages were cut and then a corner of the film stretched over each package. The first impermeable portion of the film of each package was peeled off by exfoliating the initiation point of the corner. The film was cleanly exfoliated, leaving a second permeable micro-perforated portion as the remainder of the tray lid.

Example 2 A film such as that of Example 1 was tested with fresh ground beef in a low oxygen package. A plurality of expanded polystyrene trays, manufactured by W.R. Grace & Co.-Conn., Under the designation BT972, were each filled with 1.5 pounds of ground beef and gas / vacuum irrigated to result in sealed packages containing less than 0.1% oxygen each. The packages were stored in a dark warehouse at 35 ° F for 14 days. The packages were exfoliated to allow air to enter and the meat to convert from purple to red in less than 45 minutes. The film exfoliated acceptably and both the subjective (panel of five people) and objective means (Hunter's colorimeter) judged the meat as acceptable.

Referring to the drawings, Figures 2 and 3 illustrate gaskets with a film lid that can be exfoliated by exfoliating the first gas impermeable film portion from a second gas permeable perforated film portion. These multi-layered films allow simplified packing operation, using conventional single flange trays, or vacuum, or preferably vacuum and gas-flushed with a low oxygen atmosphere and sealing a simple network of tray flange in a only step of sealing. For retail sale, the first portion of Gas impermeable film is exfoliated by revealing a second portion of gas permeable perforated film having a gas transmission rate of preferably at least 50,000 cc / mz / 24 hrs. / atm. at 73 ° F, which allows a quick release of the low oxygen atmosphere and the introduction of oxygen to achieve a rapid flowering of the product of the packed meat.

In Figure 2, a package 10 that is made using a multiple layer film according to the present invention includes a support member or tray 12 having side walls 14 and a base 16 defining an interior cavity 18 for receiving the product. 20. A peripheral flange 22 is defined around the upper portions of the side walls 14. The multiple layer film 26 is sealed to the tray in the flange 22.

Figure 3 is a cross sectional view of a portion of a package 50 as the package 10 of Figure 20, which includes a tray 52 having side walls 54 and a base not shown and which defines a cavity 58 for receiving a product. A peripheral flange 62 is defined around the upper portions of the side walls 54, with the film 66 sealed to the flange 62. For the present embodiment, the film 66 is a single coextruded multiple layer film, which can be exfoliated within of the permeable and impermeable portions. Films that can be exfoliated in this manner are well known in the art and examples have been given earlier in this description. These films are formed, for example, by coextruding a multiple layer film including two layers immediately adjacent to each other that demonstrate a weak adhesion force between them.

Adhesion resistances are equated to exfoliate the forces required to separate the permeable and impermeable portions of the film. The exfoliation forces of preference are between the range of about 0.001 to about 2.5 pounds, more preferably 0.01 to 2 pounds, as 0.05 to 1.5 pounds, and 0.1 to 1 pounds. Typically, exfoliation is initiated through a thermal seal on the perimetric flange of the product support member. The initiating force of the exfoliation will in some way be generally higher than the exfoliation force. For example, if the exfoliation force is about 0.5 pounds / inches, the exfoliation initiation force will typically be between 1.0 and 1.5 pounds / inch. In this way, the film 66 is exfoliated in a gas impermeable upper portion 68 and in a gas permeable inner portion 70, as shown.

The portion of the film 70 defined perforations 72 therein, which extend through the gas permeable portion 70 of the film. At the time of the exfoliation it is observed that the portion of the impermeable film 68 is substantially free of perforations. In an alternative embodiment, the perforations extending substantially in connection with the present invention but not completely through the permeable portion can also be beneficially used, these are commonly referred to as blind perforations.

In this way, when the impermeable portion 68 is exfoliated, the perforations 72 are defined within the remaining permeable portion 70 which allows a rapid exchange of gases and a consequent flowering of the product of the packaged meat.

Also within the scope of the present invention, although less preferred, there is provided a multiple layer film that is exfoliated into two portions, each comprising an inherent impermeable material, with the portion that is directly sealed to the support member having This alternative is less preferred because the inherent permeability of a portion of the permeable film also aids gas exchange.In areas of intimate contact of the film with the meat, a portion of perforated film that is made of an inherent impermeable material it prevents the flowering of the meat, except in the specific areas of perforation, in this way it is a non-flowering area that contains areas with flowering points, and due to the expense involved in the coextrusion of the two gas impermeable layers in a single film of multiple layer, where a layer will be subsequently perforated to become per It is generally preferred that the perforated portion be made of an inherently permeable material.

Figures 4 and 5 illustrate the packages with the films that can be exfoliated by exfoliating a first gas impervious film portion, as well as a part of a second perforated gas permeable film portion of the remaining part of the film. second portion of the movie.

Figure 4 discloses a. package 100 according to the present invention, which includes a product support member or tray 112 having side walls 114 and a base (not shown) defining an interior cavity 118 for receiving the product. A peripheral flange 122 is defined around the upper portions of the side walls 114. The multiple layer film 126 is sealed to the tray in the flange 122. For the present embodiment, the film 126 includes the portion of the gas impermeable film. 128 and the portion of the gas permeable film 130 having perforations 132 defined therein. The portion of the film 130 is capable of exfoliating into two separate components of the film, if the force required to exfoliate the portion of the film 130 into two separate components of the film is less than the force required to exfoliate the film. portion of the gas impermeable film 128 a and the portion of the gas permeable film 130.

That is, in accordance with a modality of pr v r. and invention, the portion of the film 130 was previously stored in the tcr -r. -. = > the movie 128, was rc and then relayed to the pnnon of the imperfect film 12c. However, as opposed to the peyic > As shown above, the portion of the irc-rmeatle 118 film can not quickly exfoliate from the one hundred of the film 130 to a relatively strong interlamellar anion which is criginated between the two portions at r. In this way, the adhesion strength between the portions of the film 1 fi and 130 is greater than the force of the film portion 130 of the film 130 so that any attempt can be made to reduce the size of the film 130. - Leaving the portion of the film 118 results in a failure n conesión and / or exfcii? an ie inaracapa of the portion of the film 131 -n _; ss separate components l: superior imposing 12 • - remains measured to the The immense lid film and the itfericr component 135 remain sealed to the banana tray.

Figure 5 includes a package 4C0 of confi rm: ad_cn: re_tt- invention, the r l: lve a member of: ~ rn for the product or tray 412 having side walls 414 and a base (not shown) that defines an interior cavity 418 to receive the product. A peripheral flange 422 is defined around the upper portions of the neutral pads 414. The multiple layer film 426 is attached to the tray in the flange 422. For the present rcaalidae, a 426 scale includes a portion of the film. qae is permeable to the gas 418 and a portion of the permeable gas layer layer 430 having perforations 42_ n- is defined therein. The peel of the film 430 is capable of exfoliating into two separate components of the film, if the force required to melt the portion of the film into separate components, ie the film is less than the force that is applied to the film. it requires for exfeliac the portion of the film impervious to the gas 428 to the-per c of the gas-permeable film 431.

That is to say, on the basis of the present invention, the portion of the 43C film was previously sold out of the pedestal of 428, was drilled, and the teams laughed in Iraq. A film impermear ie no. If, at the same time, you are going to go through the movie 66 before you start the movie, you can not quickly exfoliate the portion of the film 430 because A relatively strong interlaminar bond between the two portions was created at the time of re-rolling, so the resistance to adhesion between the portions 423 and 430 is greater than the interlayer adhesion strength d, e the portion of the film 430 such that any attempt to detach the film from the film 426 results in the interlayer exfoliation of the film portion 430 into separate layers 436 and 4 8 8. Thus the upper layer 436 remains attached to the portion of the waterproof film 428 and the lower layer 438 remains sealed to the flange of the tray 422.

The second portion of the film of the present invention is preferably an aterial permeable to ozone. Typically, the materials suitable for the present permeable film may include any material that can be sealed to the support member, such as polymers, especially copolymers or propylene homopolymers, or polyethylene, or any of a variety of ethylene copolymers, for example. , copolymer of vinyl acetate / ethylene, copolymer and / or ethylene, acrylic / ethylene acrylic resin, including neutral salt: each metal thereof and alpha-olefin / ethylene copolymer. a wide variety of permeable structures.

The first portion of the pellet: the permeable inlet of the present invention can be any suitable barrier layer, film or sheet which is similar to the gas in permeate, the congener is the congener, so that a fresh meat product. vane content: in another low oxygen atmosphere has an improved shelf life unlike a package that does not have the barrier layer. The polymeric materials which have barrier and gas properties for use in the present invention include ethylene vinyl alcohol copolymer, copolymer and vinylidene chloride. tt-YDCi c: mc is vinyl chloride chloride vinyl chloride? viniiinede > copelimer c of acriiat; of methyl, polyaide: ccpcliareide, e polyester and copeliester. A waterproof portion has the structure of: PXa ^ E One year, a variety of film films was p : rn: r ci ~ m i: er - - of the invention. More likely, the film used will contain at least three layers: a sealer layer, a barrier layer and an outer layer of abuse. Acemas, you can also include the inner layers as the adhesive layers - the layers of: being. Also, sheets of sealable films and non-forming materials such as polyester or nailaly or niaxially oriented are within the scope of the present invention. These sheets can be produced by corona treatment or any other suitable process.

For all modalities, the product support member should be waterproof, but can be chosen from a variety of designs and compositions available Ckcmerciaimente. That is, the product support gold can be formed from a rigid polymer, a polymer coated with tarrera sealer, a foam polymer covered with barrier sealer, or a pulp covered with barrier seliader or cardboard tray . If it is foamed, a tarrera film should be included, at least copper the inner surface of the tray in order to avoid the exit of the gas from the residual center of the gasket. The pelica to the face sealer for the tray can be, for example, the one disclosed in European Patent Publication 0 707 955 A1 published on April 24, 19 '* 6, incorporated herein by reference. in its entirety.

The scope of the invention is defined by means of the claims appended hereto and their equivalents c.

Claims (20)

1. a method for making an exfoliating film comprising: a) providing a multi-layer film; b) exfoliate the film in a first portion and in a second portion; c treat the second per ónon to increase its permeability to gas, and; d) relaying the second portion treated towards the first portion., i.

The method of the first claim, in a: nde the exfcliable movie is coexnuy.

3. The method of claim 1, wherein the expliable film has a prime, a layer and a second layer; the first and second layers are adjacent to each other and form an interiaminar interface exfoliated between the adjacent layers.

4. The method of claim 3, wherein the first adjacent layer comprises a polyethylene homopolymer or copolymer, and the second adjacent layer comprises a material selected from the group consisting of polyamide, copolyamide, pestle, copolyester, propylene homopolymer and -opclimero ae _. "pileno.

5. The method of claim 1, wherein the second portion is treated by piercing the second portion after the film has been exfoliated, and before the film is licked.

6. The method of claim 1, wherein the second portion is treated by partial perforation of the second portion after which ..

7. The method of claim 1, wherein the first portion and the second portion are joined together by the corona treatment to a surface of the first portion, and contacting the treated surface of the first anointing in the region. portion.

8. The method of claim 1, wherein the first portion and the second portion are relaminated together by the corona treatment to a surface of the second portion, and contacting the treated surface with corona of the second portion - in the first portion. portion.

9. The method of claim 1, wherein the first portion and the second portion are relaminated by thermally sealing the first and second portions.

10. The method of claim 9, wherein the first and second portions are thermally sealed under pressure.

11. The method of claim 1, wherein the crime portion and the second portion are relaminated by sealing joints ultrasonically to the first and second portions.

12. The method of claim 1, wherein the first portion and the second portion are rewound together by applying an adhesive to a surface of the first portion and contacting the treated surface of the first portion with the rest.

13. The method of claim 1, wherein the first portion and the second portion are relaid together by applying an adhesive to a surface of the second portion and contacting the surface of the second portion with the first one to be feared.

14. The method of claim 1, wherein the larger portion comprises a gas-impermeable material. 1-5.

The method of the rei? Nai -? ciar. 1, wherein the second portion comprises a gas-free material.

16. an apparatus for exfoliating film comprising: a medium for exfoliating the film in a first portion and in a second period; ba m medium to, treat the first portion to increase its permeability to gas, and; c a means for relaying the second portion to the first by?.

17. The apparatus of claim 11, wherein the means for exfoliating a film in a first portion and a second portion comprises a device that breaks the film along the peelable interface in a first and second portion.

18. The apparatus of claim 11, wherein the means for treating the permeable portion to increase its gas permeability comprises an electrostatic perforator.

19. The apparatus of claim 11, wherein the means for relaying the first treated portion to the second portion comprises the corona treater.

20. The apparatus of claim 1, wherein the means for relaying the first treated portion to the second portion comprises reheated press rolls.