Patent Application
20170137202
The invention relates to packaging, and more particularly, to modified atmosphere packaging.
The quality and shelf-life of many perishable products is critically dependent on the nature and quality of the packaging in which it is contained. For many food products, such as meats and cheeses, optimal preservation is obtained by removing as much atmosphere as possible and hermetically sealing the product. However, other food products, such as produce, continue to undergo respiration while being transported and stored, and will quickly perish and spoil if placed in a hermetically sealed container.
One approach is to use packing that is well ventilated, so that the atmosphere within the container approximates the ambient atmosphere, thereby allowing unimpeded respiration by the contained produce while it is transported and stored. This approach avoids the premature spoilage that can result from hermetic packaging, but does nothing to enhance or prolong the quality and shelf life of the produce beyond what would be obtained if the produce were not contained in a package.
Another approach is to enclose produce in packaging that allows only a very limited rate of gas exchange between the interior of the package and the surrounding environment. By tailoring the gas exchange rate to the specific type and quantity of contained produce, and taking into account the temperature and other factors, it is possible to induce a modified atmosphere within the package, whereby the oxygen level is reduced and the carbon dioxide level is increased, thereby slowing the metabolism of the produce and extending its shelf life without causing the contained produce to perish and spoil. This approach is generally referred to as modified atmosphere packaging (“MAP”). The result can be increased quality and longer shelf life, less waste from spoiled produce, better inventory control, and appreciable overall savings for the food industry at both the retail and wholesale levels.
MAP can be implemented in any of several ways. In some instances, MAP can be achieved simply by selecting an appropriate packaging material and controlling the thickness of the material so as to provide a limited permeability to oxygen and carbon dioxide. However, this approach places significant constraints on package size, packaging material, overall package strength and durability, and packaging costs. It is therefore applicable only to a limited range of circumstances.
Another approach is to use a packaging material that is essentially impermeable to gases, and to penetrate the material with one or more “microperforations,” typically having diameters measuring in the tens of microns to hundreds of microns. In this way, an optimal packaging material, and desired package size and type can be selected, and then the number, size, and placement of the micro-perforations can be adjusted so as to provide an optimal modified atmosphere for the enclosed type and quantity of produce.
While the microperforation approach to MAP has many advantages, the technology required to provide precise and consistent microperforations can be difficult and expensive to implement. Most practical implementations of MAP have depended on microperforation of a thin film or web, since these materials are easier to puncture, either with pins or with a relatively low power laser. Depending on the application, a flexible package may be constructed entirely from the microperforated web, which can be uniformly perforated, or perforated only in one more isolated “target areas.” If a more durable solution is required, a flexible package made from a microperforated web can be placed in an outer carton having large ventilation holes, and in some cases the ventilation holes can be provided in locations where they are likely to align with microperforated target areas. Nevertheless, this approach can be expensive, at least due to the requirement to provide both an inner bag and an outer carton, and it is susceptible to occlusion of the microperforations by the outer carton.
Yet another approach is to contain the produce in a rigid or semi-rigid package having an open top, and to seal the top with a microperforated film or web. This approach is effective for packages that are intended for single use, but the approach is problematic for applications where it is desirable to re-seal the package after initial use and to reestablish a modified atmosphere to prolong the shelf life of the remaining contents.
Some attempts have been made to provide a rigid or semi-rigid package with a re-sealable, rigid or semi-rigid lid that can provide a modified atmosphere for contained produce. It is typically not practical to microperforate a rigid or semi-rigid package using pins, because a pin that is strong enough to puncture a rigid or semi-rigid packaging wall is generally too large in diameter to be useful for modified atmosphere packaging. One approach is to provide a macroscopic opening in the rigid lid or the rigid base, and then cover the opening with a section of microperforated film or web. However, this approach is somewhat complex and costly because of the need to prepare and assemble at least three separate components.
With reference to
Laser perforation of rigid packaging can be even more problematic if the rigid packaging is laminated or coated with a separate, heat-activated sealant layer. With reference to
For modified atmosphere packaging, this type of rigid container 210 with laminated sealant layer 208 is attractive, because it excludes any possibility of unintended gas exchange during transport and pre-sale storage due to imperfect sealing of the lid 202 to the base 200. However, with reference to
What is needed, therefore, is a rigid, microperforated, modified atmosphere packaging container having a laminated sealant layer, wherein the container includes accurately reproducible microperforations with diameters in the range of 20 to 300 microns, the microperforations being uniform in diameter through both the rigid layer and the sealant layer of the container. What is further needed is a method of producing such a container.
A rigid, microperforated, modified atmosphere packaging container including a sealant layer is disclosed, as well as a method of producing the container, wherein the container includes accurately reproducible microperforations with diameters in the range of 20 to 300 microns, preferably between 40 and 250 microns, and wherein the microperforations are uniform in diameter within a tolerance of 10% along their lengths through both the rigid layer and the sealant layer of the container.
Rather than using a laser to create the one or more microperforations, the present invention uses micro-drills to create perforations of uniform diameter through both the rigid layer, which in embodiments is PET, and the sealant layer, which is various embodiments is polyacrylonitrile resin or polyester film. Depending on the application, the diameters of the microperforations are in the range of 20 microns to 300 microns, and preferably between 40 microns and 250 microns, with a hole diameter uniformity of better than plus or minus 10%.
The juncture between the lid and body of the disclosed container can be hermetically sealed during initial packaging by an appropriate combination of heat, pressure, and dwell time, so that the only gas exchange is through the accurately dimensioned microperforations. The one or more microperforations can be located in the base and/or lid of the container, and can be distributed in any convenient manner, including widely separated microperforations and/or microperforations concentrated in one or more “target areas.”
In some embodiments of the disclosed method, a backing support is temporarily positioned behind the wall or lid of the container in the region to be microperforated by the micro-drill. The backing support can be made from any convenient material, and can include a clearance hole to avoid contact with the micro-drill. In an automated, assembly-line production environment, each container lid or base is brought to a drilling station, its position is “registered” (for example by a low power laser and optical sensor), and the backing support is lowered into position. The microperforation(s) is/are then drilled, either by a single drill or by a plurality of drills acting simultaneously. The drill(s) and/or container lid or base can be moved after the initial drilling, and the drilling process can be repeated so as to provide the desired number of microperforations.
Embodiments of the present invention include internal wells or compartments that can be filled with differing contents. In some of these embodiments, the compartments are separated by partitions that rise to a level slightly below the lid, for example 1-2 mm below the lid, so that the contents are maintained in their respective compartments but air is able to flow throughout the package interior. In other of these embodiments, the partitions that divide the compartments extend to the lid, so that upon initial packaging the partitions are sealed to the lid by the sealant layers, creating hermetically isolated compartments that can each be ventilated by a customized configuration of microperforations so as to provide separately determined modified atmospheres in each of the compartments that are optimized for the intended contents thereof. Compartments intended to contain meat, cheese, dip, or some other content that does not benefit from respiration can be left without microperforations, so that the compartments are hermetically sealed.
One general aspect of the present invention is a rigid or semi-rigid container configured for modified atmosphere packaging of produce. The container includes a base and a lid, the lid being removably engageable and reengagable with the base so as to form a seal therebetween, the base and lid both being formed from laminated panels having outer rigid or semi-rigid layers laminated to inner sealant layers, the sealant layers being sealable to each other so as to form a hermetically sealed junction between the lid and the base. The container further includes at least one microperforation penetrating both laminated layers of one of the base and the lid, said microperforation having a length of at least 0.4 mm and a diameter between 20 microns and 300 microns, said diameter being uniform along a length of the microperforation within a tolerance of plus or minus 10%.
In embodiments, the outer layer of the laminated panel include PET, and/or the inner layer of the laminated panel includes at least one of polyacrylonitrile resin and polyester film. In certain embodiments, the diameter of the at least one microperforation is between 40 microns and 250 microns.
In various embodiments, the base of the container is divided by partitions into a plurality of compartments. In some of these embodiments, a gap of at least 0.5 mm remains between tops of the partitions and the lid when the lid is engaged with the base. In other of these embodiments, the sealant layers on tops of the partitions are hermetically sealed to the sealant layer of the lid when the lid is engaged and sealed with the base, and the compartments are thereby hermetically isolated from each other. In some of these embodiments a rate of gas exchange between each compartment and a surrounding ambient atmosphere is separately controlled according to a number and configuration of microperforations provided in the compartment. And in some of these embodiments at least one of the compartments is hermetically isolated from the surrounding ambient atmosphere.
In embodiments, the container includes a plurality of microperforations. And in some of these embodiments, the plurality of microperforations are located in at least one localized target area on at least one of the base or lid, a largest dimension of said target areas being no greater than 25% of a smallest of a height, a width, and a depth of said container.
Another general aspect of the present invention is a method for manufacturing a rigid or semi-rigid container configured for modified atmosphere packaging of produce. The method includes providing a base and a lid, the lid being removably engageable and reengagable with the base so as to form a seal therebetween, the base and lid both being formed from laminated panels having outer rigid or semi-rigid layers laminated to inner sealant layers, the sealant layers being sealable to each other so as to form a hermetically sealed junction between the lid and the base. The method further includes using a micro-drill to drill at least one microperforation through both laminated layers of one of the base and the lid, said microperforation having a length of at least 0.4 mm and said micro-drill having a diameter between 20 microns and 300 microns.
Embodiments further include, before drilling said at least one microperforation, locating a rigid backing support behind at least a localized region of the base or lid where the microperforation is to be drilled so as to inhibit the base or lid from deforming during the drilling of the microperforation.
Some embodiments further includes conveying the lid or base to a drilling station, and registering a location of the lid or base, so that the location is accurately determined. And in some of these embodiments registering the location of the lid or base includes using at least one of a laser and a light sensor.
Various embodiments further include drilling a plurality of microperforations using a plurality of micro-drills, each of the microperforation having a length of at least 0.4 mm, each of the micro-drills having a diameter between 20 and 300 microns.
And certain embodiments further include moving at least one of the base or lid and the micro-drill, and drilling at least one more microperforation.
The features and advantages described herein are not all-inclusive and, in particular, many additional features and advantages will be apparent to one of ordinary skill in the art in view of the drawings, specification, and claims. Moreover, it should be noted that the language used in the specification has been principally selected for readability and instructional purposes, and not to limit the scope of the inventive subject matter.
The present invention is a rigid or semi-rigid, microperforated, modified atmosphere packaging container including a laminated sealant layer, as well as a method of making the container, wherein the container includes accurately reproducible microperforations with diameters in the range of 20 to 300 microns, preferably 40 to 250 microns, and wherein the microperforations are uniform in diameter throughout their lengths within a tolerance of plus or minus 10% through both through the rigid layer and the sealant layer of the container laminate.
As illustrated in
The juncture between the lid 202 and body 200 of the disclosed container can be hermetically sealed during initial packaging by an appropriate combination of heat, pressure, and dwell time, so that the only gas exchange is through the accurately dimensioned microperforations 306. The one or more microperforations 306 can be located in the base 200 of the container, as shown in
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The foregoing description of the embodiments of the invention has been presented for the purposes of illustration and description. Each and every page of this submission, and all contents thereon, however characterized, identified, or numbered, is considered a substantive part of this application for all purposes, irrespective of form or placement within the application.
This specification is not intended to be exhaustive. Although the present application is shown in a limited number of forms, the scope of the invention is not limited to just these forms, but is amenable to various changes and modifications without departing from the spirit thereof. One or ordinary skill in the art should appreciate after learning the teachings related to the claimed subject matter contained in the foregoing description that many modifications and variations are possible in light of this disclosure. Accordingly, the claimed subject matter includes any combination of the above-described elements in all possible variations thereof, unless otherwise indicated herein or otherwise clearly contradicted by context. In particular, the limitations presented in dependent claims below can be combined with their corresponding independent claims in any number and in any order without departing from the scope of this disclosure, unless the dependent claims are logically incompatible with each other.
