Patent Application
20090166369
The present invention relates generally to a plastic container having a cover and a base, which when sealingly engaged together form a sealed storage area, and, more particularly, to container covers that telescope or articulate from a first position to a second position below or above the first position. Multiple covers of the plastic containers may be aligned together when stacked in a first position and may be locked together in a second position.
Rigid, thermoplastic food containers are generally known. Users often accumulate a large number of these containers in different sizes and shapes. When not in use, the containers are often stored haphazardly into drawers. In this case, the unused containers take up a great deal of room, and finding a matching base and cover in a disarranged drawer may be difficult. To avoid this, some users stack the containers in cabinets. While the bases of the containers usually nest and therefore take up less room than in a disorganized drawer, it may still be difficult to match a base with a cover. In addition, the covers may not stack and the covers may tend to topple down. When the containers are in use to store food, the containers are often stacked one on top of another in cabinets or in a refrigerator. These stacks may be precarious, and their fall may cause food to spill from the containers. Many users would find it desirable if the containers, whether empty or in use, could be stored in a manner space efficient, less precarious, and more structurally rigid. Related U.S. Provisional Patent Application No. 60/655,830, describes a system of interlocking covers for sealable plastic containers and is hereby incorporated by reference in its entirety.
During large-scale manufacturing, the covers may be transported in bulk before being separated out for individual packaging. During bulk handling, manufacturers would find it desirable if the covers would form a stack stable enough to resist the vertical and lateral movements caused by forces typically encountered during manufacturing operations. The present invention has as a general aim to provide containers that satisfy both users and manufacturers.
Users would find it desirable to provide containers that advantageously create a partial vacuum within the sealed storage area of the container during use. Still further, users would find desirable a cover that holds items in place within the container or that expands somewhat to accommodate larger items. Still further user would find it desirable to have covers that provide for cover interlocking while at the same time allow for stacking of additional containers on top of the cover of a first container. What is needed is a cover of improved flexibility that can provide these advantages.
In view of the foregoing, the present invention provides containers whose covers can be stacked together in two different ways. First, the covers can be stacked into an “aligned” stack. The aligned stack provides enough structural rigidity for bulk handling during manufacturing. Second, the covers can be stacked into a “locked” stack. The locked stack provides even more structural rigidity than does the aligned stack and is useful when storing unused covers.
In some embodiments, the cover includes a first closure portion, an engagement portion, and an alignment portion. The base includes a second closure portion. The first closure portion of the cover is sealingly engageable with the second closure portion of the base to define a substantially sealed, leak-proof, and re-sealable storage area for items such as food. The alignment portion of the cover is engageable with the alignment portion of a second cover to form an aligned cover stack. The engagement portion of the cover is engageable with the engagement portion of a second cover to form a locked cover stack.
Further, the covers of the present invention include articulation elements that allow the covers to easily flex upwardly or downwardly, sometimes referred to as articulate, either alone or when engaged with the base of the container. A protruding engagement portion of the cover may be articulated downwardly to the level of the top of the remaining portions of the cover.
The covers and bases can be economically constructed from relatively thin-gauge plastic so that the user can either wash them after use or dispose of them with the view that their purchase price allows them to be used as a consumable good. The container can be readily manufactured, for example, with conventional vacuum thermoforming equipment. The cover can be made from a semi-transparent material to ensure satisfactory visibility of the container's contents. The container can be suitable for refrigerator, freezer, microwave, and machine dishwasher use.
The features of the present invention will become apparent to one of ordinary skill in the art upon reading the detailed description, in conjunction with the accompanying drawings, provided herein.
Turning to the drawings, wherein like reference numerals refer to like elements, an embodiment of the present invention is illustrated in
The cover 102 includes an engagement portion 106 that is lockingly engageable with the engagement portion of a second cover (not shown in
The cover 102 includes a first closure portion 310 (
As shown in
More particularly with reference to the engagement portion 106, the cover 102 illustrated in
A shown in
The engagement portion 106 can also be chosen to have a shape or otherwise include elements that provide an aligned or locked stack of covers 102 with rotational alignment. Rotation, as used herein, is defined about an axis A (
Other embodiments of the engagement portion may include one or more of the following features to enable engagement: convex portions or ribs, concave portions or ribs, linear or curvilinear undercuts, discrete snap elements or buttons, interference fits, textured surfaces, or elements that modify surface friction or tackiness at or around the point of engagement. The engaging areas that create a locking condition can be continuous about the engagement portions or discretely segmented about the engagement portions. In some embodiments, the force required to connect the cover and the second cover may differ substantially from the force required to disengage the covers. For instance, it may be beneficial during manufacturing that the force needed to connect the covers is less than the force required to separate the covers. As a result, the covers are relatively easy to connect during manufacturing, yet they will lock securely and not undesirably separate during the manufacturing process. To accomplish this, the protrusions on the engagement portion may be designed where, for a given protrusion, the upper protrusion edge comprises a gradual taper whereas the lower protrusion edge comprises a more abrupt shape. For example, in one embodiment, the shape of the protrusion may be similar to a barbed hook with gradual taper on the upper edge of the barb that would impart little resistance during engagement and with an abrupt shape on the lower edge of the barb that would impart relatively high resistance during disengagement. Conversely, it may be beneficial to design the engagement portion so that the force that needs to be applied to connect the covers is more than the force required to separate the covers, since the user may perceive that a high connecting force equates to satisfactory locking integrity, whereas a weak connecting force may lead the user to perceive that the cover stack lacks the integrity required to insure the expected organizational benefit. Thus, the high connecting force provides the perceived benefit, yet a lower disengagement force does not require that the user untowardly struggle during separation of covers. To accomplish this, the protrusions on the engagement portion may be designed where, for a given protrusion, the upper protrusion edge comprises an abrupt shape whereas the lower protrusion edge comprises a more gradual taper. For example, in one embodiment, the shape of the protrusion may be a reversed barb with an abrupt shape on the upper edge of the barb that would impart relatively high resistance during engagement and with a gradual taper on the lower edge of the barb that would impart little resistance during disengagement. Furthermore, during the process where the user applies force to aligned covers in a direction normal to the general cover plane so as to lock the covers together, the engagement portion can provide tactile or audible feedback upon locking. In this way, the user would sense that the covers are connected and that no further force need be applied.
More particularly with regard to the first closure portion 310 and the second closure portion 416 forming the sealing engagement of the cover 102 and the base 104,
The first and second closure portions 310 and 416 can be configured to be slightly different in size to form an interference fit therebetween. The interference fit between the first and second closure portions 310 and 416 can provide a sealing engagement between the closure portions. As a result, when the two pieces are abuttingly engaged, a positive seal can be formed between the first and second sealing surfaces around the perimeters of the base 104 and of the cover 102. The sealing engagement of the first and second closure portions 300 and 404 can be accompanied by an audible “snap” indicating that the container is securely closed.
The base 104 of
The cover 102 of
In
If a user of container 100 supplies a sustained downwardly directed force on the top of the engagement portion 106 while supporting the peripheral edge of the cover 102 at its first closure portion 310 the cover 102 is biased downwardly forcing the cover 102 to assume a downwardly directed generally conical shape. Since the cover 102 is formed from flexible material, a return force is imparted upon the cover 102 by the elastic properties of the material of the cover 102. This return force will urge the cover 102 to return to its neutral position.
In
In
Thus, the articulation element 108 provides additional flexibility to the cover 102 to allow the engagement portion 106 to move downwardly relative to the position of the engagement portion 106 when the cover is in the neutral position of
The articulation element 108 provides advantages to cover 102 over prior art covers. For example,
Other uses for the articulation feature of the cover 102 may include creating a partial vacuum seal in the container 100 of
The cover 102 can be made by various plastic molding processes, including but not limited to vacuum thermoforming and injection molding. Vacuum thermoforming of the cover 102 is typically the most economical means for forming the cover 102. As is well know in the art, vacuum thermoforming involves the heating a suitable plastic sheet of material to a temperature at which the sheet becomes formable into a shape that is set as the plastic sheet cools. As used herein, a suitable plastic sheet is a plastic sheet that may be readily used by the vacuum thermoforming process. The heated plastic sheet is made to conform to the surface features of a single surface “male” tool by drawing the heated sheet of plastic to the surface of the tool by the force of a vacuum applied to the tool. In vacuum thermoforming, the sealed air space between the heated plastic and mold is evacuated to draw the heated plastic to contact the single male surface of the mold.
Typically, however, in vacuum thermoforming, the thickness of the finished article formed by the process is nominally uniform. A side cross-section view through the vacuum thermoformed article reveals a substantially uniform thickness profile. The “bottom” surface of the heated plastic sheet that contacts the tool surface conforms to its shape. The “top” surface of the plastic element formed in the vacuum thermoforming process does not contact a tool surface and generally resides at a uniform distance from the bottom surface of the plastic article. Only nominal thinning of the plastic material occurs when it bends and stretches around curved mold features to conform to the path of the curved surfaces of these features. As used herein, a substantially uniform thicknesses in side cross-sectional profile is a thickness in a plastic article that is not sufficiently variable to preclude its manufacture with typical prior art single male surface vacuum thermoforming techniques. Conversely, a non-uniform thickness is a profile thickness in an article that varies enough to preclude the manufacture of the article with standard prior art vacuum thermoforming techniques requiring instead other plastic molding techniques such as injection molding.
Injection molding of a plastic article involves heating suitable plastic material in the form of pellets or granules until a melt is obtained. The melt is next forced into a split-die mold, sometimes referred to as a split-die tool, where it is allowed to “cool” into the desired shape. Both the bottom surface and the top surface of the plastic article are formable by the split-die mold. Thus, articles may by formed by the injection molding process that have side cross-sectional profiles of varying non-uniform thickness. After the plastic melt cools, the split-die mold is opened and the article is ejected. Since, the mold is separable, undercut surface on the plastic article may be relieved from the split-die mold when it is opened. Injection molding, well know in the art, is typically used to form plastic articles that have large undercuts and substantially varying thicknesses in side cross-sectional profile. As used herein undercuts are said to be large if a molded plastic article having undercut features is difficult or impossible to remove from a single-surface vacuum thermoforming mold after it is formed and cooled.
Since cover 102 as described, contains significant undercuts, such as included in upper protrusion 118 and lower protrusion 120 (
A method of forming the articulated cover of the present invention using vacuum thermoforming techniques is next described. As noted above, it is advantageous that the articulation element 108 of the cover 102 has a side cross-sectional profile thickness that is less than the thickness of the cover 102. As also noted above, typical vacuum thermoforming, techniques produce plastic articles that have substantially uniform thickness profiles.
In accordance with the principles of the present invention and as best seen in
In this manner, the living hinge of the cover 102 is formed. Since the plastic material overlying the open end 1127 of the mold indent 1126 is drawn into the rectangular cavity 1128 of the mold indent 1127, the overlying plastic material is elongated, stretched, and drawn into a “V” shaped feature that is less thick than the rest of the cover 102. By increasing the strength of the separate vacuum supplied to the mold indent 1126, the depth of the “V” shaped articulation element 108 may be increased and its thickness decreased. Thus, the living hinge at the vertex of the articulation element 108 may be decreased in thickness when compared to the thickness of the remaining portions of the cover 108. Advantageously, the thickness of the living hinge may be varied in this manner without the need for retooling of the thermoforming mold 11122.
The container 100 can be reusable, but it can also be constructed cheaply enough that consumers see it as a disposable item, with replacement covers 102 and bases 104 available separately for retail sale. The base 104 and the cover 102 can be fabricated by vacuum thermoforming a clarified polypropylene homopolymer material. In another embodiment, the container 100 may be fabricated by vacuum thermoforming a clarified random copolymer polypropylene material. Other plastic materials which would be suitable for fabricating the cover 102 and the base 104 of the container 100 by vacuum thermoforming include PS (polystyrene), CPET (crystalline polyethylene terephthalate), APET (amorphous polyethylene terephthalate), HDPE (high density polyethylene), PVC (polyvinyl chloride), PC (polycarbonate), and foamed polypropylene. The material used can be generally transparent to allow a user to view the contents of the container.
The container 100 may include a visual indication of closure between the cover 1102 and the base 104. The visual indication may be a color change in the area where the cover 102 engages the base 104. In one embodiment, the first closure portion 310 on the cover 102 may be a first color and the second closure portion 416 on the base 104 may be a second color. When the closure portions are engaged, the first and second colors produce a third color which is visible to the user to indicate that the container 100 is sealed.
The container 100 may include a rough exterior surface to reduce slipping and to improve grasping by the user, especially if the user's hands are wet or greasy.
The container 100 may include a self-venting feature. The pressure in the sealed container 100 may increase when the sealed container 100 and contents are heated in a microwave oven. Thus, the cover 102 may include a self-venting mechanism, which opens when the pressure in the container 100 exceeds a predetermined value.
The container 100 may be divided to separate foods in the container. A divider may be integral with the container 100 or may be a separate component. Either the base 104 only may include a divider or both the base 104 and the cover 102 may each include a divider. The divider located in the cover 102 may only partially engage the divider in the base 104 so as to provide splash protection, or it may fully engage the divider in the base 104 to provide varying degrees of inter-compartmental leak resistance.
The container 100 may include a strip indicating the temperature of the container 100 and its contents.
The use of the terms “a,” “an,” “the,” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise indicated.
While the invention is described herein in connection with certain preferred embodiments, there is no intent to limit the present invention to those embodiments. For example, those of skill in the art would recognize that may be formed such that the vertex of the articulation element 108 is above the top of the cover 108, that is the articulation elements 108 may be pointed upwardly. It is recognized that various changes and modifications to the described embodiments will be apparent to those skilled in the art upon reading the foregoing description, and that such changes and modifications may be made without departing from the spirit and scope of the present invention. Skilled artisans may employ such variations as appropriate, and the invention may be practiced otherwise than as specifically described herein. Accordingly, the intent is to cover all alternatives, modifications, and equivalents included within the spirit and scope of the invention. Moreover, any combination of the above described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/US07/67953 | 5/1/2007 | WO | 00 | 10/27/2008 |
| Number | Date | Country | |
|---|---|---|---|
| 60803675 | Jun 2006 | US |
