Patent Publication Number: US-8113370-B2

Title: Plastic container having vacuum panels

Description:
FIELD 
     The present disclosure relates to vacuum side panels that control container deformation during reductions in product volume that occur during cooling of a hot-filled product. 
     BACKGROUND 
     The statements in this section merely provide background information related to the present disclosure and may not constitute prior art. Plastic containers, such as polyethylene terephthalate (“PET”), have become commonplace for the packaging of liquid products, such as fruit juices and sports drinks, which must be filled into a container while the liquid is hot to provide for adequate and proper sterilization. Because these plastic containers are normally filled with a hot liquid, the product that occupies the container is commonly referred to as a “hot-fill product,” and the container is commonly referred to as a “hot-fill container.” During filling of the container, the product is typically dispensed into the container at a temperature of at least 180° F. Immediately after filling, the container is sealed or capped, such as with a threaded cap, and as the product cools to room temperature, a negative internal pressure or vacuum forms within the sealed container. Although PET containers that are hot-filled have been in use for quite some time, such containers are not without their share of limitations. 
     One limitation of PET containers that receive a hot-filled product is that during cooling of the liquid product, the containers may undergo an amount of physical distortion. More specifically, a vacuum or negative internal pressure caused by a cooling and contracting internal liquid may cause the container body or sidewalls to deform in unacceptable ways to account for the pressure differential between the space inside of the container and the space outside, or atmosphere surrounding, the container. Containers with deformations are aesthetically unpleasing and may lack mechanical properties to ensure sustained container strength or sustained structural integrity while under a negative pressure. 
     Another limitation of PET containers that receive a hot-filled product is that they are not easily held by a hand of a handler, such as a consumer who is drinking the product directly from the container. For instance, intended container gripping areas typically located on the body of containers are not designed to conform to a user&#39;s hand while also accounting for the above-mentioned pressure differential resulting from hot-filled containers. 
     Another limitation of plastic containers, such as hot-fill containers, is that such containers may be susceptible to buckling during storage or transit. Typically, to facilitate storage and shipping of PET containers, they are packed in a case arrangement and then the cases are stacked case upon case on pallets. While stacked, each container is subject to buckling and compression upon itself due to direct vertical loading. Such loading may result in container deformation or container rupture, both of which are potentially permanent, which may then render the container and internal product as unsellable or unusable. 
     Yet another limitation with hot-filled containers lies in preserving the body strength of the container during the cooling process. One way to achieve container body strength is to place a multitude of vertical or horizontal ribs in the container to increase the moment of inertia in the body wall in select places. However, such multitude of ribs increases the amount of plastic material that must be used and thus contributes to the overall weight and size of the container. 
     SUMMARY 
     The present invention provides a hot-fillable, blow-molded plastic container suitable for receiving a liquid product that is initially delivered into the container at an elevated temperature. The container is subsequently sealed such that liquid product cooling results in a reduced product volume and a reduced pressure within the container. The container is lightweight compared to containers of similar size yet controllably accommodates the vacuum pressure created in the container. Moreover, the container provides excellent structural integrity and resistance to top loading from weight placed on top of the container. 
     Possessing a central vertical and a central horizontal axis, as well as a body or sidewall central horizontal axis, the container structure further employs an upper portion defining a mouth, a shoulder portion that is formed with and molded into the upper portion and that extends downward from the upper portion, a bottom portion forming a base, and a body or sidewall that extends between and joins the shoulder portion and the bottom portion. The sidewall further defines a pair of opposing columns that are oriented diagonally relative to the base and that are concave inward toward the container central vertical axis when the container is not sealed or filled with a liquid. When filled with a hot liquid that is then cooled, the opposing columns become concave inward to a lesser extent because the container interior undergoes and sustains an interior vacuum. Moreover, the body or sidewall defines a pair of opposing vacuum panels that are oriented diagonally relative to the base and that are formed with compound angles to conform to a palm of a human hand. A vacuum initiator, also called a hinge or groove, is coincident with a vacuum panel longitudinal centerline and is formed as part of each of the pair of opposing vacuum panels. 
     The vacuum initiator or groove may further define vacuum initiator walls such that upon contraction of the container liquid content, the groove walls initiate movement toward the container central vertical axis. The walls of the vacuum panels are parallel to each other at approximately a horizontal centerline of the sidewall or vacuum panel structure when viewed as a container cross section. 
     The bottom portion may have a circumferential base recession or groove, which may be horizontal and define base groove walls. The base groove may be formed outside of the vacuum panel area and at a sufficient depth to permit vertical movement of the shoulder groove walls, and thus, the container. Similarly, the shoulder of the container may define a circumferential shoulder groove defining shoulder groove walls. The shoulder groove may be horizontal and at a sufficient depth to permit vertical movement of the shoulder groove walls, and thus, the container. 
     Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
    
    
     
       DRAWINGS 
       The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. 
         FIG. 1  is a perspective view of a container depicting a sidewall with vacuum panels and columns; 
         FIG. 2  is a side view of the container depicting a sidewall vacuum panel and expansion positions of the columns; 
         FIG. 3  is a side view of the container depicting a sidewall column and contraction positions of the vacuum panels; and 
         FIG. 4  is a cross-sectional view of the container depicting contraction positions of the vacuum panels and expansion position of the columns. 
     
    
    
     DETAILED DESCRIPTION 
     The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features. 
     Referring now to  FIGS. 1-4 , and first to  FIG. 1 , a hot-fill, blow molded plastic container  10  is depicted that exemplifies principles of the present invention. The container  10  is designed to be filled with a product, typically a liquid  11  such as a fruit juice or sports drink, while the product is in a hot state, such as at or above 180 degrees Fahrenheit. After filling, the container  10  is sealed, such as with a cap  20  and cooled. During cooling, the volume of the product in the container  10  decreases which in turn results in a decreased pressure, or vacuum, within the container  10 . While designed for use in hot-fill applications, it is noted that the container  10  is also acceptable for use in non-hot-fill applications. 
     Since the container  10  is designed for “hot-fill” applications, the container  10  is manufactured out of a plastic material, such as polyethylene terephthalate (“PET”), and is heat set such that the container  10  is able to withstand the entire hot-fill procedure without undergoing uncontrolled or unconstrained distortions. Such distortions may result from either or both of the temperature and pressure during the initial hot-filling operation or the subsequent partial evacuation of the container&#39;s interior as a result of cooling of the product. During the hot-fill process, the product may be, for example, heated to a temperature of about 180 degrees Fahrenheit or above and dispensed into the already formed container  10  at these elevated temperatures. 
     As depicted in  FIGS. 1-3 , the container  10  generally includes an upper portion  12 , which defines a mouth  14 , a shoulder portion  16  and a bottom portion  18 . As depicted, the shoulder portion  16  and the bottom portion  18  are substantially annular or circular in cross-section. A cap  20  engages threads  22  on the upper portion  12  to close and seal the mouth  14 . 
     Extending between the shoulder portion  16  and the bottom portion  18  is a sidewall or body  24  of the container  10 . As depicted in  FIGS. 1-4 , the body  24  has a variety of cross-sectional shapes. Near the transition between the shoulder portion  16  and the sidewall  24 , the cross-sectional shape is circular; however, within and throughout the sidewall  24  between the shoulder portion  16  and bottom portion  18 , the cross-sectional shape varies. At a top portion  26  of the sidewall  24  and a lower portion  28  of the sidewall  24 , the cross-sectional area is circular. However, between the shoulder portion  16  and the bottom portion  18 , the cross-sectional area varies due to employment of a recessed first vacuum panel  30  and a recessed second vacuum panel  32 , which together make up a pair of opposing vacuum panels  30 ,  32 . Similarly, the sidewall  24  employs a first column  34  and a second column  36  which make up a pair of opposing columns  34 ,  36  which are located between the vacuum panels  30 ,  32 . Because the vacuum panels  30 ,  32  and columns  34 ,  36  are opposing their respective selves, that is vacuum panel  30  faces vacuum panel  32  and column  34  faces column  34  across the container volume, they alternate or are staggered around the periphery or circumference of the sidewall  24  of the container  10  in the fashion of; first vacuum panel  30 , first column  34 , second vacuum panel  32 , second column  36 . 
     Before continuing with a description of the container sidewall  24 , a brief description of the shoulder portion  16  and bottom portion  18  will be provided. The container shoulder portion  16  is generally of a conical shape with a narrower cross section that joins or forms into the upper portion  12  while the opposite end of the shoulder portion  16  has a larger cross section and meets with the sidewall  24 . The shoulder portion  16  may be equipped with one or more recessed ribs or grooves that are circular or elliptical, such as groove  38  and groove  40 . Between the shoulder portion  16  and the sidewall  24 , a transition groove  42  may exist. The grooves  38 ,  40 ,  42  may have groove walls. For instance, groove  38  may have groove walls  44 ,  46 , groove  40  may have groove walls  48 ,  50 , and groove  42  may have groove walls  52 ,  54 . As depicted in  FIGS. 1-3 , grooves  38 ,  40  may be elliptical, or non-horizontal and non-parallel to the bottom portion  18 , while groove  42  may be circular, horizontal and parallel to the bottom portion  18  or surface upon which the container may rest. The bottom portion  18  of the container may have a chime  56  located between a contact ring  58 , which contacts a surface upon which the container rests, and a bottom groove  60 . Like the other grooves in the container  10 , the bottom groove  60  has groove walls  62 ,  64 . 
     There are advantages to the grooves  38 ,  40 ,  42  and  60 . For instance, because the grooves are formed by their respective groove walls, as noted above, which project toward a container interior volume, additional strength is added to the container sidewall  24  because the material&#39;s moment of inertia is increased at the location of the grooves  38 ,  40 ,  42  and  60 . The grooves  38 ,  40 ,  42  and  60  are also known as strengthening ribs  38 ,  40 ,  42  and  60 . There is another advantage to the grooves  38 ,  40 ,  42  and  60 , and in particular, groove  42  and groove  60 . The horizontally arranged grooves  42 ,  60  are able to receive and absorb a vertically-applied, compressive load  23 , such as may be imparted on the container cap  20  when the container  10  is part of a case or pallet of containers, which may then become top-loaded with another case or pallet of containers. Because the container  10  contains the horizontal grooves  42  and  60 , the container  10  will not buckle under a shock load of a case or pallet of containers, when applied within container buckling limits. Although grooves  38 ,  40  are not horizontally arranged, they are still capable of absorbing vertical loading, especially in instances such as when one case or pallet of containers is released onto another case or pallet of containers, as in the case of an initial shock load. In such a scenario, buckling may be prevented. Additionally, the grooves  38 ,  40  act as strengthening ribs and provided circumferential strength to the shoulder portion  16  of the container  10 . 
     A description of the container sidewall  24  will now be presented.  FIGS. 1-3  depict a container sidewall  24  that employs opposing vacuum panels  30 ,  32 , which are generally oval in shape and extend vertically between the shoulder portion  16  and the bottom portion  18  of the container  10 . In the present teachings, the vacuum panels  30 ,  32  are identical, thus when only one is described, one will appreciate that the other is identical in function and structure. The first and second vacuum panels  30 ,  32  are located opposite one another such that they are generally facing each another. Thus, the “first” and “second” designations may also be thought of as “front” and “rear,” respectively; however, such designations are merely used for differentiation purposes and not to designate actual front and rear portions of the container  10 . Furthermore, while the vacuum panels  30 ,  32  generally face each other, they are not a “reflected image” or “mirror image” of each other. More specifically, the vacuum panels  30 ,  32  are arranged or angled in the same direction, thus forming an “X” when viewed through the container  10 . The significance of such an arrangement is that an even vacuum “squeeze” is experienced by the sidewall  24 . 
     The first and second vacuum panels  30 ,  32  exhibit a generally inward, arcuate shape from top to bottom between the shoulder portion  16  and the bottom portion  18 , as depicted in  FIGS. 1 and 3 . This arcuate shape may also be described as concave inward and as defining a generally oval shape. Furthermore, the oval shape may also be considered helix or helical shaped, since the vacuum panels  30 ,  32  are “twisted” and formed with compound angles. The vacuum panels  30 ,  32  are slanted or tilted such that their longitudinal centerline or longitudinal axis forms an angle that is not ninety degrees with the contact ring  58  of the bottom portion  18 . The contact ring  58  is that portion of the container  10  that contacts a surface upon which the container  10  rests.  FIG. 3  exemplifies that the sidewall  24  of the container  10  also has an approximate horizontal midpoint axis  66  at which vacuum panel  30  and vacuum panel  32  define a minimum distance across the volume of the container  10 .  FIG. 4  depicts the minimum distance between the parallel vacuum panels  30 ,  32  when not subjected to a vacuum pressure. 
     As depicted in  FIGS. 1 and 3 , the vacuum panels  30 ,  32  are also arcuately shaped in a transverse direction, or a direction parallel to a surface upon which the container  10  would rest, such that the arcuate shape is generally inwardly directed or concave. Because the vacuum panels  30 ,  32  are structured to employ such compound angles, a person handling the container  10  can grasp the container  10  with, for example, his or her right hand and the right palm will settle into or conform to the sidewall  24 , such as at location  25  of the vacuum panel  30 . Furthermore, the vacuum panels  30 ,  32  are diagonally arranged on the body or sidewall  24  of the container  10 , and thus, are able to traverse or cover a larger area of the container sidewall  24 . The advantage to such an arrangement is that the vacuum panels  30 ,  32  may be made larger than if they were arranged vertically. Additionally, because the vacuum panels  30 ,  32  are diagonal and angled across the body or sidewall  24  with respect to a horizontal surface, and larger than strictly vertical vacuum panels, fewer of them on a container may be necessary. Moreover, angled vacuum panels  30 ,  32  may have a wider or longer distance  27  across a width of a single vacuum panel  30 , as depicted in  FIG. 2 , which results in a vacuum panel  30  that is more responsive to an internal vacuum pressure within the container  10  as opposed to a panel that is not as wide, and thus stronger and more resistant to a vacuum pressure. Still yet, larger concave inward vacuum panels  30 ,  32  may provide an area large enough to accommodate a human palm to facilitate container holding. 
     The first vacuum panel  30  is equipped with a first vacuum panel hinge or groove  68 , also known as a first vacuum panel initiator  68  or simply as a first initiator  68 . Similarly, the second vacuum panel  32  is equipped with a second vacuum panel hinge or groove  70 , also known as a second vacuum panel initiator  70  or second initiator  70 . The first and second initiators  68 ,  70  are called such because upon a liquid  11  beginning to cool within the container  10 , the volume of the container  10  will begin to be increasingly displaced due to the contraction of the container  10  along the first and second initiators  68 ,  70 . Thus, the first and second initiators  68 ,  70  are the locations within the first and second vacuum panels  30 ,  32  of the sidewall  24  where the vacuum within the container  10  begins to alter the position of the vacuum panels  30 ,  32  just before the balance of the vacuum panels  30 ,  32  begins to move. More specifically, the walls  74  of the first initiator  68  and the walls  76  of the second initiator  70  will begin to be drawn toward the interior of the container  10 , such as toward the container central vertical axis  78 , as depicted with phantom lines  80 ,  82 . Upon initial movement of the first and second initiators  68 ,  70 , the balance of the vacuum panels  30 ,  32 , beginning with the portions closest to the initiators  68 ,  70 , will then begin to move toward the central vertical axis  78 , that is, toward an interior of the volume of the container  10 . 
     Separating the first vacuum panel  30  from the second vacuum panel  32  is the pair of diametrically opposed columns  34 ,  36  and it is the placement and shape of the columns  34 ,  36  relative to the vacuum panels  30 ,  32  which, in one instance, permits the vacuum panels  30 ,  32  to move toward the central vertical axis  78  and to cause the columns  34 ,  36  to move away from the central vertical axis  78 . Located on opposing sides of the container  10 , the columns  34 ,  36  are depicted in  FIGS. 1-4  to be located at each end of the vacuum panels  30 ,  32 . Furthermore, the columns  34 ,  36  are outwardly arcuate or semi-circular and resist deformation inward toward the central vertical axis  78  when the volume of the container  10  is subjected to a vacuum from a cooling liquid  11 . Moreover, the arcuate columns  34 ,  36  are also shaped to accommodate part of the palm of a person who holds the container  10 . 
     As depicted best in  FIG. 2 , the lengths of the columns  34 ,  36  extend from the shoulder portion  16  to the bottom portion  18  with the width of the columns  34 ,  36  varying over their length. As depicted in  FIG. 3 , the column  36  (from the shoulder portion  16  to the bottom portion  18 ) decreases in width to about its longitudinal midpoint and thereafter increases in width. This width variation may be generally symmetrical about a horizontal midpoint axis  66  of the column portions  34 ,  36  and present an hourglass silhouette of the column portions  34 ,  36 . In alternative embodiments, the widths of the column portions  34 ,  36  need not vary so much over their lengths, as described above, but instead the widths of the columns  34 ,  36  may remain more constant along the length of the columns from the shoulder portion  16  to the bottom portion  18 . 
     As depicted best in  FIG. 2 , the column portions  34 ,  36  exhibit a shape which is generally inwardly curved or concave when the container  10  is initially formed and before it is filled with a hot liquid. Upon hot-filling, capping and permitting the container  10  to cool, the radius of curvature in the columns  34 ,  36  will decrease. That is, the columns  34 ,  36  will more closely approach a vertical position to account for the contracting vacuum panels  30 ,  32 , which move toward the central vertical axis  78  during cooling. Because the columns more closely approach a vertical position, the ability of the container  10  to support a vertical load improves, thus when cases or pallets of the containers  10  are hot-filled and capped, they may better support stacking arrangements. 
     The transition between the columns  34 ,  36  and the vacuum panels  30 ,  32  is a step downward of sorts, or rather a decrease in the radial distance to the central vertical axis  78 , as is evident in  FIG. 4  at locations  35 . This transition defines a step downward from the columns  34 ,  36  to the vacuum panels  30 ,  32  because the columns  34 ,  36  are located at a greater radial distance from the central vertical axis  78  of the container  10  than the vacuum panels  30 ,  32 . 
     The container  10  as previously described generally addresses the container  10  as it is originally formed. The discussion will now focus on changes in the structure after hot-filling the container  10 . After a hot liquid product  11  is filled into the container  10 , the container  10  is immediately capped and begins cooling, and thus the product within the container  10  begins decreasing in volume. This reduction in product volume produces a reduction in pressure within the container  10  and begins to exert forces on the interior wall(s) of the container  10 . The vacuum panels  30 ,  32  of the container  10  controllably accommodate this pressure reduction by being pulled or contracted inward toward the central vertical axis  78 , as depicted using phantom lines  80 ,  82  in  FIG. 3 . The overall external surface area of the container  10  that the two vacuum panels  30 ,  32  occupy facilitates the ability of the vacuum panels  30 ,  32  to accommodate a significant amount of the reduced pressure or vacuum. Moreover, the inwardly recessed curved surface of the vacuum panels  30 ,  32 , formed by compound angles, are configured such that they absorb or account for at least 50% of the reduced pressure or vacuum, and preferably at least 65%, and most preferably about 85%, upon cooling of the liquid. 
     As the vacuum panels  30 ,  32  move or contract inwardly toward the central vertical axis  78 , the generally circular shape of the body or sidewall  24  permits or causes the columns  34 ,  36  to deflect radially outward from their non-filled position and into a more upright orientation. This phenomenon is depicted with phantom lines  84 ,  86  in  FIG. 2 . Additionally, a decorative embossed motif or word, such as a company name or drink name, may be molded into the columns  34 ,  36  to enhance vertical strength. 
     Because of the significant reduction in vacuum pressure of the container  10  after cooling, the container  10  has a greater propensity to not retain outwardly induced, but inwardly directed, dents which normally occur during handling or shipping. Containers with higher resultant vacuum pressures (and therefore less vacuum accommodation) tend to retain or hold such dents as a result of the vacuum forces themselves. The novel shape of the container  10  further lends the container  10  to light weighting as the vacuum panels  30 ,  32 , given their orientation, require less material than if a circular sidewall were used in their place.