Abstract:
A resilient microwavable container including a bowl and a selectively detachable snap on lid is disclosed. The lid includes a plurality of protrusions which snap over a pair of annular flanges extending outwardly from the bowl whereby a distinct clicking sound can be heard to verify the lid is properly attached.

Description:
BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The present invention generally relates to a container useful for storing and transporting items such as food and, more particularly, to a container including a bowl and a snap fit selectively detachable lid. 
     2. Description of the State of the Art 
     Containers, particularly those used for reheating foodstuffs in a microwave oven generally should be relatively low in cost and easy to utilize. Additionally, such containers should be versatile to use, that is, capable of withstanding drastically different environments such as occurs when transferring the container directly from the refrigerator or freezer to a microwave oven, for example. 
     With regard to these microwavable containers, while a primary focus in the art has been on providing a good seal between the lid and the bowl, relatively little attention has been paid to the physical integrity of the mechanical attachment between the lid and the bowl. Further, known commercially available microwavable containers fail to provide an audible sound which is indicative that the lid and the bowl are in sealing engagement upon attachment. 
     OBJECTS AND SUMMARY OF THE INVENTION 
     It is therefore a primary object of the present invention to provide a container including a bowl and a selectively detachable lid including a sealing arrangement which allows for relatively easy attachment and detachment. 
     Another object of the present invention is to provide a low cost, high production volume container made from a resilient material. 
     Still another object of the present invention is to provide a container which provides an audible sound upon attachment of the lid to the bowl which is indicative that a good seal has been made. 
     Still another object of the present invention is to provide a lid which resists inadvertent detachment from the corresponding bowl. 
     Yet another object of the present invention is to provide a resilient container which is useful in various environments such as refrigerator freezers and microwave ovens. 
     In accordance with the teachings of the present invention, a microwavable container is provided that includes a bowl and a selectively detachable lid, each having outwardly extending lips. The bowl and lid lip have at least one, and preferably, a series of protrusions and flanges thereon which slidingly engage each other during attachment and detachment of the lid from the bowl in such a manner that an audible clicking sound is made to verify that the container is sealed. The cooperation of the protrusions with the flanges, in the sealed position, resists inadvertent detachment of the lid from the bowl. In one embodiment, the bowl lip includes at least one substantially annular outwardly extending flange and the lid lip has at least one inwardly extending protrusion. In an alternative embodiment, the bowl lip includes at least one outwardly extending protrusion while the lid lip includes at least one inwardly extending flange. 
     The container of the present invention can be economically thermo-formed from any one of a number of known thermoplastic resins including but not limited to polyamides, polyacrylics, polyarylates, polycarbonates, polyesters, polyetherimides, polyetherketones, polyolefins, polyphenylenes, polyvinylchlorides, and various styrene and liquid crystal polymers, among others. 
     The various features, objects and advantages of the present invention should become still more apparent from a review of the following description of the drawings and invention in detail. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a disassembled perspective view of a container made in accordance with the teachings of the present invention; 
     FIG. 2 is a disassembled sectional view of the container of FIG. 1 taken along line  2 — 2 ; 
     FIG. 3 is an assembled perspective view of the container. 
     FIG. 4 is a disassembled perspective view of an alternative embodiment of a container made in accordance with the teachings of the present invention; and 
     FIG. 5 is a disassembled sectional view of the container of FIG. 4 taken along line  5 — 5 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring generally to FIG. 1, there is shown a container  10  including a bowl  12  and selectively detachable lid  14  formed in accordance with the teachings of the present invention. From the outset, it should be noted that while the container is illustrated generally as being round, the container may be of various other configurations such as oval, rectangular or square by way of non-limiting examples. 
     The bowl  12  generally includes a bottom  16  and a continuous side wall  18  extending vertically from the bottom defining a bowl cavity  88 . Integrally connected to the vertically extending sidewall is a substantially L-shaped continuous lip  20  including a first leg  24  which extends outwardly from the sidewall and a second leg  26  which extends downwardly from the first leg. The second leg  26  of the continuous lip includes a pair of spaced apart outwardly extending substantially annular flanges  80  and  82 , respectively. By “substantially annular” it is meant the flanges  80  and  82  should extend around a majority of the second leg, however the flanges need not be continuous. 
     As can be seen more clearly with reference to FIG. 3, the upper portion  22  of the sidewall  18  preferably includes an inwardly extending annular nub  28  which assists in confirming the sealing engagement between the lid and the bowl as will be described in greater detail below. 
     The lid  14  generally includes a body  30  having a peripherally disposed lip  32  which overlays a portion of the lip  20  provided on the bowl upon attachment. The lip  32  generally has an inverted U-shape in cross section including a first leg  34  which extends from the body, a second leg  36  and a web  38  disposed therebetween as shown most clearly in FIG.  3 . Extending inwardly from the second leg  36  of the lip  32  is a plurality of spaced apart circumferentially spaced protrusions  84 . The protrusions  84  which generally are disposed in proximity to the terminal edge  86  of the second leg  36  are preferably rounded to reduce the separation force required to detach the lid from the bowl. Preferably, the total number of protrusions will include at least 10 and, more preferably, will number 20 or more. As illustrated, it is also preferable that the protrusions  84  be spaced equidistantly about the lip  32 . 
     Upon joining the lid  14  to the bowl  12 , the protrusions  84  snap over both annular flanges  80  and  82  thereby assisting in securing the lid to the bowl. As the protrusions snap over the annular flanges, the snap action provides a distinctive clicking sound which provides an auditory indication that the interfitting seal between the lid and bowl has been accomplished. This so-called interfitting seal occurs when the first leg  34  of lip  32  is advanced over the annular nub  28  until the sealing point engages the inner surface of the side wall  18 , as shown in FIG.  3 . 
     A rigid tab member  40  designed to resist bending at the point of attachment to the sealing lip  32  is provided and extends outwardly from the second leg  36 . The tab member  40  which is substantially triangular in shape is shown as including a floor  42  and a peripheral edge  44 . The floor  42  is provided with a plurality of spaced apart upstanding ribs  46  including a first rib  50  disposed along a longitudinal center line drawn through the tab as designated by reference numeral  48 . Disposed on opposite sides of the first rib, are second and third ribs  52  and  54 , respectively, which extend angularly away from the longitudinal center line  48 . Each of the ribs are defined by rather abrupt edges which further enhance the structural rigidity of the tab member. 
     The ribs are positioned at specific locations to maximize the tab&#39;s rigidity and thereby enhance the transfer of separation forces from the tab member to the sealing region, i.e., enhance the releasability of the lid from the bowl when desired. For example, the first rib  50  includes a first transverse edge relative to the floor which extends at an angle of between about  3 ° to about  7 ° from the longitudinal center line and a second transverse edge extending at an angle of between about −3° to about −7° from the longitudinal center line. Thus, the first rib is generally trapezoidal in shape. 
     The second rib  52  includes a first transverse edge extending at an angle of between about 8° to about 12° from the longitudinal center line  48  and a second transverse edge extending at an angle of between about 20° to about 40° from the longitudinal center line. The third rib  54  which is the mirror image of the above described second rib extends at an angle of between about −8° to about −12° along a first transverse edge and at an angle of between about −20° to about −40° from the longitudinal center line along a second transverse edge. Thus, as shown and described with regard to the preferred angular orientations, the second and third ribs extend angularly away from the longitudinal center line and are substantially triangular in shape. 
     It should be noted that the negative degree designations (−°) relative to the longitudinal center line are utilized herein for clarity and to emphasize that the second and third ribs are preferably mirror images of each other. As such, one skilled in the art should readily recognize, for example, that −3° is equivalent to 357° and −7° is equivalent to 353° utilizing standard radius expressions. 
     According to a preferred embodiment, each of the upstanding ribs include a first end  70  terminating proximate to the lip  32  and a second end  72  terminating proximate to the peripheral edge  44  of the tab. The upstanding ribs are generally sloped upwardly from the second end to the first end at an average inclination of between about 12° to 18° such that the ribs join the lip  32  near the junction  76  between the web  38  and second leg  36 . The peripheral edge of the tab member preferably includes a downturned flange  74  which extends below the floor  42  and thus provides a barrier to prevent a user&#39;s thumb or finger from sliding off of the tab member. 
     In order to remove the lid from the bowl, the user pulls up on the tab member  40  to break the interfitting seal  5 . As the lid is pulled away from the bowl, the protrusions  84  are thus pulled over the annular flanges  80  and  82  thus causing the same clicking sound as is heard upon attachment of the lid. 
     Referring to FIG. 4, there is shown an alternative embodiment of the container  10 . According to this embodiment, a series of protrusions  84   a  are disposed on the second leg  26  of the bowl&#39;s lip  20  and the substantially annular flanges  80   a  and  82   a  extend inwardly from the second leg  36  of the lid&#39;s lip  32 . Thus, the flanges  80   a  and  82   a  respectively snap over the protrusions  84   a  which results in the unique clicking sound heard upon attachment and detachment of the lid from the bowl. In other respects, the container is preferably the same as the container shown in FIGS.  1 - 3 . 
     As should be understood upon review of the foregoing description, the lid and bowl assembly forming the container are provided with a significant mechanical resistance to undesired detachment of the lid from the bowl. However, the mechanical resistance offered by the annular flanges and protrusions do not substantially increase the separation force required to break the interfitting seal when detachment of the lid from the bowl is desired. Further, the audible clicking sound which is heard upon attachment of the lid to the bowl clearly indicates to the user that a sealing relationship between the components has been accomplished. 
     As noted, while the lid and bowl may be thermo-formed from any one of a number of different polymeric materials, a polypropylene homopolymer optionally including a slip agent is considered to be preferable. Bu utilizing a polypropylene homopolymer, the lid and bowl can be thermo-formed to have an average thicknesses of between about 10 to 50 mils and still offer the necessary structural integrity. 
     While it will be apparent that the preferred embodiments of the invention disclosed are well calculated to fulfill the objects stated, it will be appreciated that the invention is susceptible to modification, variation and change without departing from the spirit thereof.