Patent Application
20080302799
The application generally relates to metal food containers. The application relates more specifically to metal food containers with screw-top closures and methods of making the same.
Metal containers are used to store a variety of materials and objects. Some types of metal containers are used to store perishable material such as organic material, solid food, food having a liquid component, and liquids. These containers must often meet a variety of requirements depending on their intended use. For example, some containers must be able to withstand acidity of certain levels such that the container's intended contents do not compromise the container. Other containers must be able to successfully store liquid such that manipulation of the container during shipping and typical use do not cause the container to deform, break an airtight seal, and/or leak the container's contents. Yet other containers must be able to withstand food cooking processes involving the container.
While some containers are filled with uncooked food or pre-cooked food then sealed for later consumption, other containers are filled with uncooked food, the container is sealed, and the food is cooked or sterilized while sealed within the container. This process is commonly called a thermal retort process. Thermal retort processes often have certain advantages. First, cooking food within the container is often faster than cooking food outside of the container. Second, cooking the food inside the container helps to sterilize the food and the container. Third, end-users often appreciate pre-cooked food contents as preparation times are often shorter and more convenient. Fourth, sealing food contents then sterilizing via a thermal retort process helps maintain the seal and preserves the food contents.
Many conventional containers used with thermal retort processes use ends that may only be opened once and are not easily reclosed or resealed. For example, some conventional containers suitable for use with thermal retort processes are metal cans having an end designed for use with a can-opener. Other conventional containers suitable for use with thermal retort processes are metal cans having “pop-tops”, “pull tops”, convenience ends, or convenience lids. Thermal retort processes present challenges to the design and manufacture of reclosable and/or resealable metal cans. For example, the pressure and temperature rigors of the thermal retort process may compromise the seal with the thread structures. In addition, traditional methods of making metal food containers are often incompatible with the precise forming steps often required to create adequate reclosable structures (e.g., screw-top threads).
Therefore, it is desirable to provide a metal container having a reclosable feature. Further, it is desirable to provide a reclosable metal container suitable for use with thermal retort processes. Further, it is desirable to provide a reclosable metal container having a screw-top that end-users may conveniently open and reclose. Further, it is desirable to provide a reclosable metal container having threads and a closure capable of withstanding a thermal retort process.
What is needed is a container and/or method of making the same that satisfies one or more of these needs or provides other advantageous features. Other features and advantages will be made apparent from the present specification. The teachings disclosed extend to those embodiments that fall within the scope of the claims, regardless of whether they accomplish one or more of the aforementioned needs.
One embodiment relates to a food or drink container kit. The container kit includes a metal container including a round threaded neck having at least one integrally formed thread. The container kit also includes a metal press-on, twist-off closure comprising a round skirt including a gasket material located on at least a portion of the interior of the skirt, a seal forming between the neck and skirt when the closure is placed on the container and heated.
Another embodiment relates to a method for creating a metal container with a press-on, twist-off closure. The method includes providing a blank of material and forming a cup from the blank of material. The cup has a closed cup end, side walls, and an open cup end. The method further includes forming the closed cup end to create a neck and a primary container opening and forming at least one thread in the neck. The method yet further includes attaching a bottom part to the open cup end to form a metal body that is closed except for the primary container opening, such that once the metal container is filled, once the press-on, twist-off closure is pressed onto the neck, and once the container is heated, a seal is formed between the closure and the metal container.
Another embodiment relates to a container made by a process. The process includes filling a metal container with food, the container comprising a preservative coating lining interior surfaces of the container and a threaded neck having at least one integrally formed thread configured to receive a closure. The process further includes pressing a press-on, twist-off closure onto the threaded neck, the closure comprising an interior surface and a plastisol gasket material lining at least a portion of the interior surface, wherein after heating the closure a seal is created with the threaded neck, capable of withstanding a heating and cooling process such that the plastisol gasket material lining the interior surface of the closure resiliently engages the at least one integrally formed threads. The process yet further includes heating the container to sterilize the food contained within the container and to create a vacuum that provides a physical force that helps securably hold the closure onto the container.
Another embodiment relates to a food or drink storage apparatus. The storage apparatus includes a metal container including a round threaded neck having at least one integrally formed thread. The storage apparatus also includes a metal press-on, twist-off closure comprising a round skirt including a gasket material located on at least a portion of the interior of the skirt, a seal forming between the neck and skirt when the closure is placed on the container and heated.
Alternative exemplary embodiments relate to other features and combinations of features as may be generally recited in the claims.
The application will become more fully understood from the following detailed description, taken in conjunction with the accompanying figures, wherein like reference numerals refer to like elements, in which:
Before turning to the figures which illustrate the exemplary embodiments in detail, it should be understood that the application is not limited to the details or methodology set forth in the following description or illustrated in the figures. It should also be understood that the phraseology and terminology employed herein is for the purpose of description only and should not be regarded as limiting.
Referring generally to the figures, a metal container (i.e., a can) is shown having a threaded neck integrally formed from the metal of the container body. The threads are formed to fit a screw-top closure and the closure is a press-on/twist-off closure. The container is suitable for use with a thermal retort process. Referring still to the figures in general, a process of making a metal container is provided so that the integrally formed threads are formed from a relatively unworked or un-thinned portion of metal once the majority of the container body has been formed.
Referring to
According to an exemplary embodiment, the metal of container 1 is about 0.008 inches thick and is primarily made of tin plated steel. According to various other exemplary embodiments, the metal of container 1 is formed from steel having a working gauge range from about 0.006 inches thick to about 0.013 inches thick, or other available working ranges. According to various other alternative embodiments, container 1 may be formed of aluminum, tin free steel, and/or another metal material that may be used to form metal food containers. The material of container 1 may also be more or less thick along certain structures or locations of body 4. For example, in the middle of the side walls of container body 4, the material may be more thin than material closer to the top end or bottom end.
The top of container 1 and container body 4 angles inward to create a frusto-conical portion 8. A threaded neck 10 extends from the frusto-conical portion 8. According to an exemplary embodiment, frusto-conical portion 8 is angled around thirty-seven degrees from the vertical surfaces of body 4 and sized so that the diameter of the neck with a closure installed thereon is smaller than the diameter of body 4. According to various other embodiments, frusto-conical portion 8 is angled more or less than thirty-seven degrees from vertical. This sizing and structure may create an aesthetically pleasing container top, provide a user with increased leverage for opening the screw-top, and/or prevent the container top, threads, and closure from experiencing some amount of the unavoidable contact that containers typically have with adjacent containers or other structures during manufacture, shipping, and/or use. According to other various exemplary embodiments, frusto-conical portion 8 may not be present on the container, may be characterized as a cone-shaped shoulder area, or may take any other shape or size.
Referring to
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According to an exemplary embodiment, thread 14 is a single thread conforming to the Glass Packaging Institute's (GPI) glass finish designation number 465, last revised Feb. 5, 1999. According to other alternative embodiments, different thread designations or specifications may be used to create the container's threads (e.g., GPI glass finish designation number 2215, etc.).
Neck edge 16 will generally be curled or rounded to provide a suitable sealing surface (e.g., uniform and having some substantial diameter relative to the gauge of the container walls). Neck edge 16 may also be curled or rounded to provide a suitable surface for mouth contact or drinking. For example, neck edge 16 is shown as a curled neck edge, curling to the exterior of threaded neck 10. The exterior diameter of the neck and structures of the neck may be appropriately sized to allow the closure to function properly. According to an exemplary embodiment, the neck is sized per certain threading specifications (e.g., GPI glass finish designation number 2215, 465, etc.).
Referring to
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According to an exemplary embodiment, the metal of closure 40 is between about 0.006 inches and 0.008 inches thick. Closure underside or interior surface 41, along at least some of the closure skirt portion 44, is coated with a gasket or gasket material 50. According to an exemplary embodiment, gasket 50 is a plastisol material or compound applied to the top and side surfaces of closure underside 41. Materials other than plastisol may serve as the gasket. Plastisol may provide sufficient resistance to acids of food products that may come into contact with the plastisol, may permit hot-fill processes to produce a vacuum seal, and may withstand a heat-based sterilization or cooking process. A sufficient amount of the gasket material coats closure underside 41 such that the outer diameter of thread 14 is larger than the inner diameter of gasket 50. The plastisol compound does not contain preformed thread indents or receiving structures. Rather, steam or another application of heat is used to soften the plastisol material prior to pushing the material onto the threaded neck of the container. The difference between the diameter of the gasket material and the structures of threaded neck 10 cause the softened gasket 50 to move and flow around thread 14 so that many portions of threaded neck 10 are surrounded by gasket 50 such that the interface(s) between threaded neck 10 and gasket 50 form a hermetic seal. Following cooling of the plastisol, the plastisol stiffens or hardens to create a resilient foam that may act to maintain the hermetic seal with threads 14. The cooled plastisol may have a semi-permanent or permanent impression of the structures of the threaded neck such that the closure may be removed and/or reclosed or resealed with a twist-off or twist-on motion.
According to an exemplary embodiment, gasket 50 specifically comprises a plastisol compound that may be characterized as a “508 compound” or similar material. Gasket 50 may be a liquid applied gasket or any other suitable gasket material.
Referring to
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A blank may be formed from the lubricated raw material or otherwise provided (step 802). The blank may be sized such that the blank may be formed to create the container body. Blanks may be formed using a variety of processes including cutting processes. For example, the blanks may be formed using a press cut-activity. A cupping press machine may cut a blank that is shaped like a disk. Once a blank has been formed or otherwise provided, the blank is formed into a cup (step 804). This cup forming activity may take place within the same machine and close-in-time to the blank cutting step. For example, a single machine may act in a double action; a first action may cut the blank and a second action may form the cup. A cup may then be ejected and advanced to the can handling system.
The cup formed from the blank may be a relatively short or squat cup. The bottom of the cup will be approximately the same metal thickness as the original blank. The sides of the cup may be worked slightly and may be thinner than the original metal of the blank. Depending on the target height of the metal container, the cup will be subjected to a drawn and ironed process that forms the container body shape from the cup (step 806). The container body shape may be formed using a machine generally referred to in the art as a “bodymaker.” This machine works or forms the cup with a punch and ironing rings in a progression to form the shape and size of the container's body walls. While this drawn and ironed process allows the container to be formed to a height taller than the cup, the ironing reduces the wall thickness and often results in the walls being too thin and/or brittle to reliably form fine and precise structures such as threads. The base of the formed container, however, is still approximately the same metal thickness as the original blank (i.e., the original cup base is still the base of the formed container as of this step, and is relatively unworked and un-thinned). This relatively unworked or un-thinned container base may be reliably formed into the thread. So, the base of the formed container shape, or the cup bottom, becomes the top of the final container body and the container neck is formed using the base of the formed container (step 808). During this step or another step, the container neck may be cut to create the primary container opening that the closure will cover. According to various exemplary embodiments, the primary container opening may be cut prior to forming the neck from the base of the formed container.
After the neck has been formed and the primary container opening has been cut, threading may be formed from the container neck (step 810). The threading may be formed using an interior press, an exterior press, and/or any other suitable thread forming process. The threads may be formed to fit a press-on twist-off closure. According to an exemplary embodiment, the thread or threads may also be formed such that a threaded neck and thread metal thickness of about at least 0.007 inches is maintained. In addition to maintaining a certain thickness of the metal, it may be important to maintain a certain low percentage of thinning. For example, while the sides of the container may be thinned during the drawing process down to about forty percent of the original thickness of the blank, the metal used to form the threaded neck and the threads should not be thinned by more than ten percent of the original blank thickness. According to an exemplary embodiment, no portion of the threaded neck and/or threads are thinned more than 12 percent and maintain a thickness of about at least 0.007 inches. According to various alternative embodiments, greater thinning percentages (e.g., thread thinning of greater than 12 percent, thinning of up to 30 percent, etc.) may be used to create the threaded neck and/or threads. According to yet other various embodiments, container wall and/or thread thickness may be less than 0.007 inches.
According to various exemplary embodiments, the threading will be thick enough and resilient enough to withstand various typical thread forming and container handling processes. The threading should be prominent enough so that when human applied rotation of the closure relative to the container body occurs, the threads provide enough leverage in the plastisol to break the vacuum seal (e.g., around 20 inHg) holding the closure onto the container body. The threading may thereby be configured to allow the consumer easy initial access to the container contents and thereafter allow the consumer to reclose the container with sufficient thread-provided leverage and threading accuracy to create a liquid-type seal (i.e., substantially watertight) upon reclosure.
The container end opposite the neck (i.e., the can bottom end) may be fixably enclosed (step 812) after a variety of steps in the process. According to an exemplary embodiment, a container bottom end part is attached to the container end opposite the neck (i.e., the can bottom end shown in
After both the top end and bottom end of the container are formed, the container may be filled (step 814). While the open container may be filled with any variety of materials or contents, the container is filled with food according to an exemplary embodiment. The food may be pre-cooked, partially pre-cooked, warmed, or cool. According to an exemplary embodiment, the container is hot-filled.
Once the container has been filled, the closure may be pressed onto the threaded neck (step 816). Step 816 may include heating the closure prior to and/or during the activity of pressing the closure onto the threaded neck. According to an exemplary embodiment, the closure is a press-on, twist-off closure lined with a plastisol material. The plastisol may be partially fluid, softened, and/or heated prior to pushing the closure onto the threads such that the friction between the plastisol material and the threaded structures is low enough to allow the closure to be fully applied (i.e., installed, slidably installed, rotatably installed) and/or formed around the threads (e.g., pressed onto the threads). According to an exemplary embodiment, steam or hot air may be applied to the closure to adequately soften the plastisol material prior to pressing the closure onto the threads. According to various exemplary embodiments, the steam temperature applied to the closure is around 190 degrees Fahrenheit to 210 degrees Fahrenheit.
The container may be subjected to a thermal retort process (step 818). A thermal retort process may generally be characterized as a process of subjecting the filled and closed container to a cooking or sterilization process having different heat, time, and pressure variables sufficient to substantially sterilize the interior and contents of the food container. Some thermal retort processes may be overpressure thermal retort processes where pressure outside the container is substantially matched or slightly exceeded relative to the pressure that builds on the inside of the container due to heating a sealed container. Overpressure thermal retort processes may generally include inserting a filled and closed container (or group of containers) into a retort vessel that heats the container via steam, water, or a combination of steam and water and provides overpressure to prevent container deformation or breakage due to pressure build-up inside the container.
During a thermal retort process, the container and the food inside the container will be brought to a temperature of about at least 200 degrees Fahrenheit. According to various exemplary embodiments, a thermal retort process may include bringing the container to a temperature of between 220 degrees Fahrenheit and 260 degrees Fahrenheit. According to yet other embodiments, a thermal retort process includes bringing the container to a temperature of at least 240 degrees Fahrenheit. According to a preferred embodiment, the container and closure should be able to withstand a thermal retort process of about 250 degrees Fahrenheit with about 32 pounds per square inch of overriding pressure for a period of about 45 minutes and a 3 pounds per square inch differential between overriding pressure and internal pressure. Processing step 818 may also include steps of controllably ramping up temperature, cooking, and then controllably bringing temperature down or dropping temperature so that a strong vacuum (e.g., 20 inHg to 25 inHg,) is formed between the closure and container body that substantially holds the closure onto the neck and maintains the hermetic seal. According to various other exemplary embodiments, a weaker or stronger vacuum may be created and maintained.
The specifications of the thermal retort process will vary depending on the food being cooked, the machinery (e.g., retort vessel) being used, the amount of agitation used with the heat, and any number of other variables. It may be desirable to cook different types of food to certain different minimum temperatures for certain different minimum amounts of time to ensure sterilization. A container and closure of the present application should be able to withstand a variety of typical temperature, time, and pressure levels such that the container may be considered suitable for use with a thermal retort process for a wide variety of foodstuffs, including, for example, adult nutritional drinks, to those skilled in the art of food sterilization using a retort process.
During the manufacturing process, the metal container may also be washed and coated as required for workability, cleanliness of the container, and longevity of the container surfaces when subjected to container contents, liquids, and/or air.
Referring to
According to one alternative embodiment, it may be desirable to pre-coat the interior of a metal food container to ensure that a thorough and even application of protective coating is applied to the interior of the container. Using pre-coated blanks of material, however, it may be desirable to form the container using a process other than a drawn and ironed process described above. In this process, a container may be formed using one or more steps to form the basic shape of the container. More particularly, a metal container using pre-coated material may be made by the process of forming a container body from a blank of pre-coated metal, forming a threaded neck from a top end of the container body to create an integrally formed thread configured to receive a closure, and filling the container body with foodstuffs. Once filled, the process may further include pushing a closure onto the threaded neck, the closure and the threaded neck creating a hermetic seal when subjected to a heating and cooling process such that a plastisol material lining the interior of the closure resiliently engages the threads and a vacuum provides a physical force to hold the closure onto the container top end.
According to various other exemplary embodiments, the interior and/or exterior of the container are coated with a preservative coating after the container is formed or substantially formed. According to yet other exemplary embodiments, the container is pre-coated and then coated with one or more post-forming coats. Coating may be applied via spraying or any other suitable method. Different coatings may be provided for different food applications. The coating material may be a vinyl, polyester, epoxy, and/or other suitable preservative spray. The coating, for example, may be a spray epoxy such as PPG Z12215L, sold by PPG Industries, Inc. According to other embodiments, the coating may be a coating such as sold by Valspar Coatings (e.g., coating number 6256-069, etc.).
According to various exemplary embodiments, a user of various embodiments of a metal container described throughout this application may open the container by applying an opening torque to the closure, container body, and/or other structures of the container to rotatably remove the closure. Using the thread indents or molds created in the plastisol, the thread surfaces should be able to slide along the interfacing plastisol such that the closure is directed upward by the spiral or helix nature of the threads. With enough twisting, the closure will be directed upward until the hermetic seal between the closure and the container will be broken and the vacuum inside the container will be released. If the closure has a safety-button type incorporated, a safety-button formerly depressed when the vacuum was maintained will pop-up to indicate to the user that the seal has been broken.
According to any preferred embodiment, although the container includes a closure at the top end, and a bottom end part at the bottom end, the container embodies a 2-piece can in that one continuous blank of material forms the container body, neck, and threads and a vertical seam or weld line does not run down the side wall of the container. According to various alternative embodiments, the container may be a three-piece can wherein a flat blank or sheet of material is shaped or bent until a first side and a second side of the shaped sheet may be welded together.
As the container and the food inside the container are heated, the inside of the container is sterilized so that the food does not spoil. When the container begins cooling, the closure is fixed to the threads by the plastisol cooling and a negative pressure relationship or a vacuum that develops on the container interior. As the plastisol cools, it hardens and forms around the threads of the container and resembles a resilient foam. As the container interior cools, a vacuum creates a physical force that provides a seal between the closure and the rest of the container interior.
It should be understood that the phrase “food” used to describe various embodiments of this disclosure may refer to dry food, moist food, liquid, or any other drinkable or edible material, regardless of nutritional value.
According to various other embodiments, a container kit may be provided utilizing various containers and closures described herein.
While the exemplary embodiments illustrated in the figures and described herein are presently preferred, it should be understood that these embodiments are offered by way of example only. Accordingly, the present application is not limited to a particular embodiment, but extends to various modifications that nevertheless fall within the scope of the appended claims. The order or sequence of any processes or method steps may be varied or re-sequenced according to alternative embodiments.
It is important to note that the construction and arrangement of the container as shown in the various exemplary embodiments is illustrative only. Although only a few embodiments have been described in detail in this disclosure, those skilled in the art who review this disclosure will readily appreciate that many modifications are possible (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters, mounting arrangements, use of materials, colors, orientations, etc.) without materially departing from the novel teachings and advantages of the subject matter recited in the claims. For example, elements shown as integrally formed may be constructed of multiple parts or elements, the position of elements may be reversed or otherwise varied, and the nature or number of discrete elements or positions may be altered or varied. Accordingly, all such modifications are intended to be included within the scope of the present application. The order or sequence of any process or method steps may be varied or re-sequenced according to alternative embodiments. In the claims, any means-plus-function clause is intended to cover the structures described herein as performing the recited function and not only structural equivalents but also equivalent structures. Other substitutions, modifications, changes and omissions may be made in the design, operating conditions and arrangement of the exemplary embodiments without departing from the scope of the present application.
It should be noted that although the figures herein may show a specific order of method steps, it is understood that the order of these steps may differ from what is depicted. Also, two or more steps may be performed concurrently or with partial concurrence. It is understood that all such variations are within the scope of the application.
