Abstract:
A plastic container having a first portion, a second portion, and a waist between the first portion and the second portion. The waist includes a first angled portion coupled to the first portion, a second angled portion coupled to the second portion, and a curved portion connecting the first angled portion to the second angled portion for forming a deformable region for preventing a catastrophic failure of the waist when the plastic container is filled and capped and subjected to an external force.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates generally to a plastic container, and more particularly to a plastic container having controlled top load characteristics.  
         [0003]     2. Related Art  
         [0004]     Container waists are known to provide the necessary rigidity to prevent ovalization of the container sidewalls and/or dome. U.S. Pat. No. 5,303,834 discloses a recessed circumferential ring, known as a “waist,” in the side wall of the container to minimize shape distortion caused by filling with a hot product. This ring prevents a cylindrical container from ovalizing, especially in the tapered shoulder section of the container. However, such conventional container waists may not provide the requisite structure to prevent catastrophic failures of the dome caused by toploading.  
       BRIEF SUMMARY OF THE INVENTION  
       [0005]     Exemplary embodiments of the invention provide a plastic container having a first portion, a second portion, and a waist between the first portion and the second portion. The waist includes a first angled portion coupled to the first portion, a second angled portion coupled to the second portion, and a curved portion connecting the first angled portion to the second angled portion for forming a deformable region for preventing a catastrophic failure of the waist when the plastic container is filled and capped and subjected to an external force.  
         [0006]     In a further exemplary embodiment of the invention, to prevent a catastrophic failure of the waist of a plastic container, a deformable region controllably deforms in response to an external force, an internal pressure of the container increases radially, and a net vertical force is produced on a non-vertical surface of the container.  
         [0007]     In a further exemplary embodiment of the container, the second portion of the container has a body of the container, a bumper coupled to an upper portion of the body and a base coupled to a bottom portion of the body. In such an embodiment, the second angled portion of the waist extends from said bumper at an angle and the angle reduces when the container is subjected to the external force.  
         [0008]     Further objectives and advantages, as well as the structure and function of preferred embodiments will become apparent from a consideration of the description, drawings, and examples. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]     The foregoing and other features and advantages of the invention will be apparent from the following, more particular description of a preferred embodiment of the invention, as illustrated in the accompanying drawings wherein like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements.  
         [0010]      FIG. 1  depicts an exemplary embodiment of a container according to the present invention;  
         [0011]      FIG. 2A  depicts a cross-sectional view of an exemplary embodiment of a container according to the present invention;  
         [0012]      FIG. 2B  depicts a cross-sectional view of an exemplary embodiment of a container according to the present invention;  
         [0013]      FIG. 3  depicts schematically distribution of topload forces in an exemplary container embodying the present invention; and  
         [0014]      FIG. 4  depicts cross-sectional view of an exemplary embodiment of a container according to the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0015]     Embodiments of the invention are discussed in detail below. In describing embodiments, specific terminology is employed for the sake of clarity. However, the invention is not intended to be limited to the specific terminology so selected. While specific exemplary embodiments are discussed, it should be understood that this is done for illustration purposes only. A person skilled in the relevant art will recognize that other components and configurations can be used without parting from the spirit and scope of the invention. All references cited herein are incorporated by reference as if each had been individually incorporated.  
         [0016]      FIG. 1  depicts an exemplary embodiment of a container  10  according to an embodiment of the present invention. Container  10  may include an upper portion  11 , a lower portion  12 , a waist  13 , and a base  14 . Upper portion  11  may include a dome  15 , and a finish  16 , which has an opening  17  for receiving and pouring liquids. In an exemplary embodiment of the invention, dome  15  may be a bell-shaped dome. Lower portion  12  may include a container sidewall  18  that merges with base  14  and a label bumper  19  that merges with waist  13 . In an exemplary embodiment of the invention, container sidewall  18  may be substantially cylindrical.  
         [0017]     In an exemplary embodiment of the invention, as is sown in  FIG. 1 , for example, dome  15  of upper portion  11  may include vertical area  15   v  for labeling. In such an embodiment, vertical area  15   v  may contribute to optimizing toplaod resistance because the vertical surface is less likely to buckle during toploading, as will be explained in further detail below with respect to  FIG. 3 .  
         [0018]     Container  10  may be used to package a wide variety of liquid, viscous or solid products including, for example, juices, other beverages, yogurt, sauces, pudding, lotions, and soaps in liquid or gel form.  
         [0019]     In an exemplary embodiment of the invention, container  10  may be made by conventional blow molding processes including, for example, extrusion blow molding, stretch blow molding and injection blow molding.  
         [0020]     Further, container  10  may have a one-piece construction and may be prepared from a monolayer plastic material, such as a polyamide, for example, nylon; a polyolefin such as polyethylene, for example, low density polyethylene (LDPE) or high density polyethylene (HDPE), or polypropylene; a polyester, for example polyethylene terephthalate (PET), polyethylene naphtalate (PEN); or others, which can also include additives to vary the physical or chemical properties of the material. For example, some plastic resins can be modified to improve the oxygen permeability.  
         [0021]     Alternatively, the container may be prepared from a multilayer plastic material. In such an embodiment, the layers can be any plastic material, including virgin, recycled and reground material, and can include plastics or other materials with additives to improve physical properties of the container. In addition to the above-mentioned materials, other materials often used in multilayer plastic containers include, for example, ethylvinyl alcohol (EVOH) and tie layers or binders to hold together materials that are subject to delamination when used in adjacent layers. A coating may be applied over the monolayer or multilayer material, for example to introduce oxygen barrier properties. In an exemplary embodiment, the present container may be prepared from PET using a stretch blow molding process.  
         [0022]      FIG. 2A  depicts a cross-sectional view of an exemplary waist  20  according to an embodiment of the present invention. Waist  20  may include a first angled portion  21  that merges with a dome wall  24  of the upper portion a container, a second angled portion  22  that merges with the label bumper  25  of a lower portion of a container, and a curved portion  23  that connects the first angled portion  21  to the second angled portion  22 .  
         [0023]     In an exemplary embodiment of the invention, second angled portion  22  may merge with label bumper  25  on the lower portion of a container at an angle θ. In an exemplary embodiment of the invention, for container that is not undergoing an external force caused by toploading, for example, angle θ may be between about 90° and 135°, for example, approximately 117°. As an external force from toploading, for example, is applied to a container, angle θ may be reduced.  
         [0024]     As is shown in  FIG. 2A , second angled portion  22  may have two endpoints A 1 , B 1  that define a distance L 1A , which may be equal to the length of second angled portion  22 . In an exemplary embodiment of the invention, distance L 1A  may be between about 0.25 and 2.00 inches. In a further exemplary embodiment of the invention, distance L 1A  may be approximately 0.55 inches. Similarly, first angled portion may have two endpoints G 1 , H 1  that define a distance L 2A , which is equal to the length of the flat surface of first angled portion  21 . In an exemplary embodiment of the invention, distance L 2A  may be between about 0.00 and 1.75 inches. In a further exemplary embodiment of the invention, distance L 2A  may be approximately 0.15 inches. In an exemplary embodiment of the invention, L 1A  may be greater than L 2A .  
         [0025]     Further, as is shown in  FIG. 2A , curved portion  23  may have an innermost point  26  that defines a longitudinal axis L. In an exemplary embodiment of the invention, when an external force is applied to a container, for example, by toploading, curved portion  23  may displace axially about longitudinal axis L.  
         [0026]     In an alternate exemplary embodiment of the invention, as is shown in  FIG. 2B , second angled portion  22  may have a length L 1B  that may be defined as the radial distance from longitudinal axis L to the exterior point where curved portion  22   c  of second angled portion  22  meets vertical area  25   v  of label bumper  25 . Similarly, first angled portion  22  may have a length L 2B  that may be defined as the radial distance from longitudinal axis L to the exterior point where curved portion  21   c  of first angled portion  21  meets vertical area  24   v  of dome  24 . In such an embodiment, a ratio L 2B : L 1B  may be defined. In an exemplary embodiment of the invention, the ratio L 2B : L 1B  may 0 to 0.5. In a further exemplary embodiment of the invention, the ratio L 2B : L 1B  may be 0.375.  
         [0027]      FIG. 3  depicts a cross-sectional view of an exemplary embodiment of container  30 . In such an embodiment, container  30  has improved topload characteristics when filled and capped. Topload refers to external forces that are applied to sealed containers as they are packed and shipped. Filled containers are typically packed in bulk in cardboard boxes, or plastic wrap, or both. A bottom row of packed filled containers is likely to support several upper tiers of filled containers, and potentially, several upper boxes of filled containers. Therefore, it is important that the containers have a top loading capability that is sufficient to prevent distortion from the intended container shape.  
         [0028]     Conventional containers have exhibited a limited ability to withstand top loading during filling, capping and stacking for transportation. Overcoming these problems is important because it would decrease the likelihood of a container&#39;s top or shoulder being crushed, as well as inhibiting ovalization in this area. It is important to be able to stack containers so as to maximize the use of shipping space. Due to the weight of liquid-filled containers, the boxes often need reinforcing such as egg crate dividers to prevent crushing of the containers. The vulnerability of the containers to crushing can be increased by the deformation resulting from the added weight on the stacked containers.  
         [0029]     As shown in  FIGS. 3-4 , improvement in topload characteristics is achieved by the present invention through a controlled failure of the waist to eliminate catastrophic buckling of the container walls and increase internal resistance.  
         [0030]      FIG. 4  depicts a cross-sectional view of an exemplary embodiment of a waist  40  that is subjected to an external force, such a toploading. As shown in  FIG. 4 , the solid lines represent an exemplary waist  40  that may be part of a container that is capped and filled, but has not been subject to an external force, while the dashed lines represent an exemplary waist  40  that may be part of a container that is capped and filled, and has been subjected to an external force TL. When a container comprising waist  40  is subject to an external force TL, such as toploading, a downward force may be exerted on the dome  44 . As the external force TL is applied, an innermost point  46  of curved portion  43  of waist  40  may displace about a longitudinal axis L, and may cause second angled portion  42  to deform. When this occurs, for example, second angled portion  42  may sag inward and the angleθ, may be reduced to approximately 45 to 134°. In a further exemplary embodiment of the invention, the angle θ, may be reduced to approximately 90°.  
         [0031]     In an exemplary embodiment of the invention, this improvement may be achieved through an effective “weakening” of the waist. In an exemplary embodiment of the invention as shown in  FIG. 3 , when the external force, such as a top load force C is applied to a container, the plastic is able to deflect and/or deform about endpoints A and B in the waist as shown by the arrows marked D. This deflection, in a filled and capped container, raises the internal pressure of the container labeled E. An increase in the internal pressure will resist the top load C by producing a net vertical force, labeled F, across all non-vertical surfaces of the container. In other words, when a top load C is applied to container  30 , container  30  will yield vertically in such a way to maximize the displacement of internal volume, increase the internal pressure of container  30  and therefore optimize topload resistance.  
         [0032]     In contrast to the present invention, prior containers have generally used a rigid waist portion specifically designed to resist deformation, i.e., be strengthened rather than weakened. Although this strengthening can prevent ovalization, when a topload force is applied, deformation must occur in some other portion of the container. This deformation can result in catastrophic buckling at the weakest point of the container, which may be in the dome sidewall or base, particularly where plastic in these regions is made thin during a molding process. By intentionally weakening the waist to permit a more predictable deflection or folding, the present invention takes advantage of the resulting internal pressure developed within the container to create a force resistant to toploading and catastrophic buckling of the container.  
         [0033]     The embodiments illustrated and discussed in this specification are intended only to teach those skilled in the art the best way known to the inventors to make and use the invention. Nothing in this specification should be considered as limiting the scope of the present invention. All examples presented are representative and non-limiting. The above-described embodiments of the invention may be modified or varied, without departing from the invention, as appreciated by those skilled in the art in light of the above teachings. It is therefore to be understood that, within the scope of the claims and their equivalents, the invention may be practiced otherwise than as specifically described.