Sealable bag having an integrated timer/sensor for use in vacuum packaging

Abstract

A vacuum bag comprises a first panel and a second panel, wherein each panel comprises a gas-impermeable base layer and a heat-sealable inner layer with at least one panel having a timer and/or sensor embedded or encapsulated by the inner layer. The timer and/or sensor can be used to monitor storage time, contents, and/or the condition of packaged products, or can be used to protect contents. This description is not intended to be a complete description of, or limit the scope of, the invention. Other features, aspects, and objects of the invention can be obtained from a review of the specification, the figures, and the claims.

Description

FIELD OF THE INVENTION

The present invention relates to bags for use in vacuum packaging and methods and devices for manufacturing bags for use in vacuum packaging.

BACKGROUND

Methods and devices for preserving perishable foods such as fish and meats, processed foods, prepared meals, and left-overs, and non-perishable items are widely known, and widely varied. Foods are perishable because organisms such as bacteria, fungus and mold grow over time after a food container is opened and the food is left exposed to the atmosphere. Most methods and devices preserve food by protecting food from organism-filled air. A common method and device includes placing food into a gas-impermeable plastic bag, evacuating the air from the bag using suction from a vacuum pump or other suction source, and tightly sealing the bag.

A bag for use in vacuum packaging can consist of a first panel and second panel, each panel consisting of a single layer of heat-sealable, plastic-based film (for example, polyethylene). The panels are sealed together along a substantial portion of the periphery of the panels by heat-sealing techniques so as to form an envelope. Perishable products, such as spoilable food, or other products are packed into the envelope via the unsealed portion through which air is subsequently evacuated. After perishable products are packed into the bag and air is evacuated from the inside of the bag, the unsealed portion is heated and pressed such that the panels adhere to each other, sealing the bag.

U.S. Pat. No. 2,778,173, incorporated herein by reference, discloses a method for improving the evacuation of air from the bag by forming channels in at least one of the panels with the aid of embossing techniques. Air escapes from the bag along the channels during evacuation. The embossing forms a pattern of protuberances on at least one of the panels. The protuberances can be discrete pyramids, hemispheres, etc., and are formed by pressing a panel using heated female and male dies. The first panel is overlaid on the second panel such that the protuberances from one panel face the opposite panel. The contacting peripheral edges of the panels are sealed to each other to form an envelope having an inlet at an unsealed portion of the periphery. The perishable or other products are packed into the envelope through the inlet, and the inlet is sealed. Thereafter, an opening is pierced in a part of the panel material that communicates with the channels, air is removed from the interior of the envelope through the channels and opening, and the opening is sealed. This type of bag requires two additional sealing steps after the perishable or other product is packed into the envelope. One further problem is that embossing creates impressions on the plastic such that indentations are formed on the opposite side of the panel

To avoid additional sealing steps, a vacuum bag is formed having a first panel and a second panel consisting of laminated films. Each panel comprises a heat-sealable inner layer, a gas-impermeable outer layer, and optionally, one or more intermediate layers. Such a bag is described in U.S. Pat. No. Re. 34,929, incorporated herein by reference. At least one film from at least one panel is embossed using an embossing mold to form protuberances and channels defined by the space between protuberances, so that air is readily evacuated from the vacuum bag.

U.S. Pat. No. 5,554,423, incorporated herein by reference, discloses still another bag usable in vacuum packaging. The bag consists of a first and second panel, each panel consisting of a gas-impermeable outer layer and a heat-sealable inner layer. A plurality of heat-sealable strand elements are heat bonded at regular intervals to the inner layer of either the first panel or the second panel. The spaces between strand elements act as channels for the evacuation of air. The strand elements are extruded from an extrusion head and heat bonded to the heat-sealable layer by use of pressure rolls. Separate equipment is required for producing strand elements, and a procedure of heat bonding a plurality of strand elements at regular intervals to the heat-sealable inner layer is complicated. Also, various shapes of pattern are hard to form using this process.

BRIEF DESCRIPTION OF THE FIGURES

Further details of embodiments of the present invention are explained with the help of the attached drawings in which:

FIG. 1A is a perspective view of a method for manufacturing a vacuum bag in accordance with one embodiment of the present invention;

FIG. 1B is a side view of the method shown in FIG. 1A illustrating the embossing method used in an embodiment of the present invention;

FIG. 1C is a close-up view of a portion of FIG. 1B;

FIG. 2 is a plan view of an exemplary timer/sensor on a panel in accordance with embodiments of the present invention, manufactured by the process shown in FIGS. 1A-1C;

FIG. 3 is a cross-section of a portion of a panel as illustrated in FIG. 2, according to an embodiment of the present invention; and

FIG. 4 is a perspective view of a vacuum bag in accordance with one embodiment of the present invention.

DETAILED DESCRIPTION

FIGS. 1A-1C illustrate one embodiment of a method for manufacturing a vacuum bag in accordance with the present invention. The vacuum bag comprises a first panel and a second panel, wherein each panel comprises a gas-impermeable base layer 108 and a heat-sealable inner layer 106 with at least one panel having a timer and/or sensor embedded inside the vacuum bag. A laminating roll 102 and a cooling roll 104 are arranged so that the heat-sealable inner layer 106 can be laminated to the gas-impermeable base layer 108 as the melt-extruded resin is cooled. As illustrated in FIG. 1C, the gap between the laminating roll 102 and the cooling roll 104 can be controlled according to specifications (for example, thickness) of a panel for use in vacuum packaging. The temperature of the cooling roll 104 is maintained in a range such that the melt-extruded resin is sufficiently cooled to form the desired pattern. For example, a temperature range of about −15° C. to about −10° C. can be sufficient to properly form the desired pattern. The temperature range of the cooling roll 104 can vary according to the composition of the resin, the composition of the gas-impermeable base layer 108, environmental conditions, etc. and can require calibration. Also, the cooling roll 104 can be sized to have a larger diameter than the laminating roll 102, thereby bringing the melt-extruded resin into contact with more cooled surface area. For example, the diameter of the cooling roll 104 can be about one-and-a-half to about three times as large (or more) as that of the laminating roll 102.

The heat-sealable inner layer 106 typically comprises a thermoplastic resin. For example, the melt-extruded resin can be comprised of polyethylene (E) suitable for preserving foods and harmless to a human body. A vacuum bag can be manufactured by overlapping two panels such that the heat-sealable inner layers 106 of the two panels can be brought into contact and heat can be applied to a portion of the periphery of the panels to form an envelope. The thermoplastic resin can be chosen so that the two panels strongly bond to each other when sufficient heat is applied.

The gas-impermeable base layer 108 is fed to the gap between the cooling roll 104 and the laminating roll 102 by a feeding means (not shown). The gas-impermeable base layer can be comprised of polyester, polyamide, ethylene vinyl alcohol (EVOH), nylon, or other material having similar properties and capable of being used in this manufacturing process, and also capable of being heated. The gas-impermeable base layer 108 can consist of one layer, or two or more layers. When employing a multilayer-structured base layer, it should be understood that a total thickness thereof is also adjusted within the allowable range for the total gas-impermeable base layer 108.

An extruder 110 is positioned in such a way that the melt-extruded resin is layered on the gas-impermeable base layer 108 by feeding the melt-extruded resin to the nip between the cooling roll 104 and the gas-impermeable base layer 108. The resin is fed through a nozzle 112 of the extruder 110. The temperature of the melt-extruded resin is dependent on the type of resin used, and can typically range from about 200° C. to about 250° C. The amount of resin to be extruded into the laminating unit 100 is dependent on the desired thickness of the heat-sealable inner layer 106.

A pattern fabricated on the circumferential surface of the cooling roll 104 in accordance with one embodiment of the present invention can include cavities for suspending timers and/or sensors for encapsulation by melt-extruded resin. Timers and/or sensors 124 can be seeded in cavities of the cooling roll 104, for example by a label machine 114 attached to the extruder 110. The resin melt-extruded by the nozzle 112 is pressed between the cooling roll 104 and the gas-impermeable base layer 108 and flows into the cavities of the cooling roll 104 and surrounds the timers and/or sensors. The timer and/or sensor can be any device capable of communicating information to a user. For example, active radio frequency identification tags (RFID), such as the PowerID Smart Active Labels (SAL) system manufactured by Power Paper Ltd. of Israel, contain batteries and can be used as disposable timers. Sensors such as the PowerID SALs can be user activated, are thin and flexible, and low-cost, while at the same time are non-toxic in case of package penetration. Alternatively, the timer and/or sensor can be connected with the gas-impermeable base layer 108, for example by adhesives, before the gas-impermeable base layer 108 is fed to the cooling roll 104, thereby eliminating the need for cavities of the cooling roll 104. Alternatively, the sensor can be a temperature sensor having chemistry that can change color if exposed to specific temperatures for prolonged periods of time. In this way a user can estimate the freshness of packaged foods or other degradable products. The resin quickly cools and solidifies with the timer and/or sensor impregnated or embedded in the resin, while adhering to the gas-impermeable base layer 108, thereby forming the heat-sealable inner layer 106 of the panel. The heat-sealable inner layer 106 can be formed while the resin is sufficiently heated to allow the resin to flow, thereby molding the resin, unlike other methods adopting a post-embossing treatment where the heat-sealable inner layer is drawn by a die or embossed between male and female components.

In other embodiments, chemicals such as silver chloride or silver halide, for example, can be added to the melt-extruded resin such that molecules of the chemicals are transparent to visible light in the absence of UV light (such as artificial light), thereby allowing the user to view the contents. When exposed to UV rays, as in direct sunlight, the molecules undergo a chemical process that causes them to change shape. The new molecular structure absorbs portions of the visible light, causing the film to darken. The number of molecules that change shape varies with the intensity of the UV rays. In this manner, contents of the vacuum bag can be protected from the harmful effects of UV rays. A laminated film formed by the heat-sealable inner layer 106 and gas-impermeable base layer 108 can be fed to a second cooling roll (not shown) for adding a second inner layer, thereby forming a barrier between the impregnated resin material and the packaged product.

In other embodiments, chemicals such as potassium permanganate, for example, can be added to the melt-extruded resin such that products that can spoil in the presence of ethylene can be preserved for a longer period as the ethylene is absorbed by the impregnated layer. A laminated film formed by the heat-sealable inner layer 106 and gas-impermeable base layer 108 can be fed to a second cooling roll for adding a second inner layer, thereby forming a barrier between the impregnated resin material and the packaged product that prevents chemicals from leaching into the product, while allowing ethylene gas to be absorbed through the barrier. One of ordinary skill in the art can appreciate the myriad different ways in which timers and/or sensors can be added to a vacuum bag.

FIG. 2 is a plan view of a panel 220 formed by the cooling roll 104 for use in a vacuum bag, in which the heat-sealable inner layer 106 is molded in such a way that a timer/sensor 124 is embedded in the heat-sealable inner layer 106. The timer/sensor 124 can be activated to measure the amount of time a product has been packed or stored. Optionally, a second timer/sensor 226 can be embedded in the heat-sealable inner layer 106 such that the temperature of the bag can be monitored. One of ordinary skill in the art can appreciate the different methods for monitoring the vacuum bag and the contents of the vacuum bag.

FIG. 3 is a cross-section of a portion of a panel 220 in accordance with one embodiment of the present invention. The heat-sealable inner layer 106, can range, for example, from about 0.5-4.0 mils in thickness between timers and/or sensors, while the gas-impermeable base layer 108 can range, for example, from about 0.5-8.0 mils in thickness. A second heat-sealable inner layer optionally added, can add an additional 0.5-4.0 mils in thickness.

The features and structures described above can be combined with other manufacturing techniques to form a valve or other structure, or tray, as described in the cross-referenced provisional applications, incorporated herein by reference. In other embodiments, the circumferential surfaces of the cooling rolls 104 described above can optionally include protuberances for forming perforations (not shown), such that a bag can be separated from a roll of bags by a customer.

FIG. 4 illustrates a bag for use in vacuum packaging in accordance with one embodiment of the present invention. The vacuum bag 450 comprises a first panel 220 and a second panel 422 overlapping each other. A timer and/or sensor is formed on the first panel 220 in accordance with an embodiment described above. The second panel 422 (or first panel 220) optionally includes channels (not shown) along a portion of the panel for evacuating air and other gases from the bag. The channels can be formed, for example, as described in the cross-referenced application “LIQUID-TRAPPING BAG FOR VACUUM PACKAGING,” incorporated herein by reference. The heat-sealable inner layer 106 and the gas-impermeable base layer 108 of the first and second panels 220,422 are typically made of the same material respectively, but can alternatively be made of different materials that exhibit heat-sealability and gas-impermeability respectively. As described above, the heat-sealable inner layer 106 is used as an inner layer and the gas-impermeable base layer 108 is used as an outer layer. The lower, left, and right edges of the first and the second panel 220,422 are bonded to each other by heating, so as to form an envelope for receiving a perishable or other product to be vacuum packaged. Once a perishable or other product is placed in the vacuum bag 450, air and/or other gases can be evacuated from the bag 450, for example by a vacuum sealing machine as described in U.S. Pat. No. 4,941,310, which is incorporated herein by reference. Once the air and/or other gases are evacuated to the satisfaction of the user, the inlet can be sealed by applying heat, thereby activating the heat-sealable inner layers 106 and bonding them together.

The foregoing description of preferred embodiments of the present invention has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obviously, many modifications and variations will be apparent to the practitioner skilled in the art. The embodiments were chosen and described in order to best explain the principles of the invention and its practical application, thereby enabling others skilled in the art to understand the invention for various embodiments and with various modifications that are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the following claims and their equivalence.

Claims

1. A bag adapted to receive an article, comprising: a first panel defining at least one molded portion; a second panel; and the first panel and the second panel secured together to form the bag; wherein the at least one molded includes at least one of a timer and a sensor.

2. A bag adapted to receive an article, comprising: a first panel having: a first outer layer; and a first inner layer connected with the first outer layer, the first inner layer including at least one of a timer and a sensor integrally formed with the first inner layer; and a second panel connected with the first panel such that the first panel and the second panel form an envelope having an inlet, the second panel having: a second outer layer; and a second inner layer connected with the second outer layer.

3. The bag of claim 2, wherein the first outer layer and the second outer layer comprise a gas-impermeable material.

4. The bag of claim 3, wherein the gas-impermeable material is one of polyester, polyamide, ethylene vinyl alcohol, and nylon.

5. The bag of claim 2, wherein the first inner layer and the second inner layer comprise a thermoplastic resin.

6. The bag of claim 5, wherein the thermoplastic resin is polyethylene.

7. The bag of claim 2, wherein the first inner layer includes at least one timer.

8. The bag of claim 7, wherein the at least one timer is an active radio frequency identification tag.

9. The bag of claim 2, wherein the first inner layer includes at least one sensor.

10. The bag of claim 9, wherein the at least one sensor is a temperature sensor.

11. The bag of claim 9, wherein the at least one sensor is a temperature sensor.

12. The bag of claim 2, wherein the first inner layer includes UV activated chemicals.

13. The bag of claim 12, wherein the UV activated chemical is one or both of silver chloride and silver halide.

14. The bag of claim 2, wherein the first inner layer includes at least one chemical for preserving the article.

15. The bag of claim 14, wherein the chemical is potassium permanganate.

16. A bag adapted to receive an article, comprising: a first panel including: a first gas-impermeable layer; and a first inner layer laminated to the first gas-impermeable layer, the first inner layer having at least one of a timer and a sensor; a second panel including: a second gas-impermeable layer; and a second inner layer laminated to the second gas-impermeable layer; and wherein the first panel is connected with the second panel to form an envelope such that the first inner layer opposes the second inner layer, the envelope including a heat-sealable opening for evacuating gas.

17. A heat-sealable bag adapted to receive an article, comprising: a first panel including: a first gas-impermeable layer; at least one first intermediate layer connected with the first gas-impermeable layer; and a first inner layer laminated to the at least one first intermediate layer, the first inner layer having at least one of a timer and a sensor; and a second panel including: a second gas-impermeable layer; at least one second intermediate layer connected with the second gas-impermeable layer; and a second inner layer laminated to the at least one second intermediate layer; wherein the first panel is connected with the second panel to form an envelope such that the first inner layer opposes the second inner layer, the envelope including a heat-sealable opening for evacuating gas.

18. The bag of claim 17, wherein the first gas-impermeable layer and the second gas-impermeable layer comprise one of polyester, polyamide, ethylene vinyl alcohol, and nylon.

19. The bag of claim 17, wherein the first inner layer and the second inner layer comprise a thermoplastic resin.

20. The bag of claim 19, wherein the thermoplastic resin is polyethylene.

21. The bag of claim 17, wherein the first inner layer includes at least one timer.

22. The bag of claim 21, wherein the at least one timer is an active radio frequency identification tag.

23. The bag of claim 17, wherein the first inner layer includes at least one sensor.

24. The bag of claim 23, wherein the at least one sensor is a temperature sensor.

25. The bag of claim 23, wherein the at least one sensor is a temperature sensor.

26. The bag of claim 17, wherein the first inner layer includes UV activated chemicals.

27. The bag of claim 26, wherein the UV activated chemical is one or both of silver chloride and silver halide.

28. The bag of claim 17, wherein the first inner layer includes at least one chemical for preserving the article.

29. The bag of claim 28, wherein the chemical is potassium permanganate.

30. A system for forming a bag including a three-dimensional structure formed on at least one panel, comprising: an implant including at least one of a timer and a sensor; a cooling roll having one or more structures for positioning the implant; a laminating roll; a backing material; and a flowable material that can be flowed into the one or more structures to envelop the implant, the flowable material adhering to the backing material.