Abstract:
A molded polymeric container generally symmetric about a vertical axis includes at least two rows of panels disposed circumferentially around the body, the panels having central portions that are sufficiently flexible to be dimensionally responsive to changes in pressure within the container. At least one row of the panels has a margin having a horizontal width exceeding the vertical height, thus being laterally elongate with a height/width aspect ratio of less than one. The pressure responsive central portion of each laterally elongate panel is a smooth outwardly projecting dome from a peripheral root of a generally radially projecting wall defining the margins of circumferential rings and posts separating the panels. The outwardly projection domes of the laterally elongate panels can have a variety of shapes.

Description:
BACKGROUND  
       [0001]     1. Technical Field  
         [0002]     The present invention is directed to molded plastic bottles capable of being filled with liquids at elevated temperature. The present invention is particularly directed to such containers having at least two vertically spaced circumferential rows of pressure or vacuum responsive panels.  
         [0003]     The present invention particularly relates to blow-molded containers of biaxially oriented thermoplastic materials such as polyethylene terephthalate that are designed to be filled with a hot liquid or semi-liquid product and hermetically sealed, generally referred to as thin-walled, hot-fill containers. The invention pertains to improvements in the design of such containers intended to achieve a container side wall construction that provides enhanced support during filing and subsequent handling and, despite the low weight of polymer used to form the container, retains the desired container configuration despite the development of a partial vacuum within the container when capped and cooled.  
         [0004]     2. General Background  
         [0005]     It is well recognized that the exposure of any plastic container to elevated temperatures tends to soften the plastic material and make the container less resistant to deformation. It is also well known to thermally treat some plastic containers during manufacturing so that this tendency is diminished to the point that the containers do not deform when hot-filled. Such thin-walled, hot-fill containers are typically used for packaging beverages and other food products that must be placed in the container while hot, the containers being quickly capped to preserve the quality of the contents. During the filling process, the container and head space gasses are subjected to temperatures from the hot product. The container is capped container is then cooled at least to ambient temperature, and perhaps refrigerated, which causes the liquid contents and any head space gases to contract. This is reflected in a drop in internal pressure, or the development of an internal vacuum within the container, which can deform the container. It is well known to compensate for the temperature induced pressure change by providing the container with a plurality of panels having sufficient flexibility and/or elasticity to permit a change in container volume that will at least partially compensate for the pressure changes.  
         [0006]     Alberghini et al. U.S. Pat. No. 5,054,632 discloses a container that is intended to be hot-filled including at least two circumferential rows of essentially square panels providing controlled volumetric reduction of the container. A land or post separates each adjacent pair of panels in each row. The rows of panels are staggered with respect to each other such that the lands or posts of one row are vertically aligned with the center of the panels of any adjacent row. The design is said to distribute circumferentially the vertical and horizontal support for any label applied to the label panel of the container while still providing the desired panel movement in response to the existence of a partial vacuum within the container due to hot filling.  
         [0007]     Krishnakumar et al. U.S. Pat. Nos. 5,178,289 and 5,279,433 disclose hot-fill containers having a plurality of vertically elongated vacuum panel regions that are symmetrically disposed about a horizontal centerline of the container label panel. They also disclose hot-fill containers having a plurality of vertically paired, generally square vacuum panel regions that are symmetrically disposed about a horizontal centerline of the container label panel. Vertical stiffening ribs are provided between horizontally adjacent vacuum panel recesses or pairs. Additional vertical stiffening ribs are provided in the center of islands or spot label areas within the pairs of vacuum panel regions. The angular extent of the vacuum panel regions and spot label areas is said to be variable to adjust the resistance to barreling and/or to provide a squeezable container.  
         [0008]     Darr U.S. Pat. No. 5,690,244 discloses a unitary plastic bottle having a central axis, an upper dispensing end, a lower freestanding base, and a generally round side wall having upper and lower extremities respectively connected to the upper dispensing end and the lower freestanding base. The side wall of the container has at least three vertically spaced horizontal ribs of an annular shape extending around the container. The side wall also has at least twelve vertical ribs spaced circumferentially and extending between the horizontal ribs and cooperating therewith to define at least twelve essentially square panels spaced around the container between each adjacent pair of horizontal ribs, and the panels being capable of flexing inwardly to accommodate for shrinkage upon cooling after hot filling of the container.  
         [0009]     Ota et al U.S. Pat. No. 6,575,320 discloses a container suitable for hot-fill use with a body having a pair of body portions that are arranged in a longitudinal direction of the body one above the other. Each body portion has a substantially regular polygonal cross-section defined by a plurality of generally flat walls. The generally flat walls of each of the body portions include flexible walls and less-flexible walls, which are arranged alternately to each other in a circumferential direction of the body. When the container is filled with liquid contents at a high temperature and subsequently cooled to room temperature, a resultant pressure drop within the container is absorbed by the walls, initially by a primary inward deflection of the flexible walls and subsequently by a secondary inward deflection of the less-flexible walls  
         [0010]     Despite the variations disclosed in the prior art, there is a continuing need for an improved molded plastic container having a side wall that exhibits outstanding dimensional stability under the typical conditions experienced during and subsequent to hot-fill and capping. In particular there is a continuing need for such a container that will provide sufficient side wall stability and support to inhibit buckling in the event of side wall impact and will provide a more stable feel to the user of the container.  
       BRIEF SUMMARY  
       [0011]     A molded polymeric container of the present invention satisfies such needs by providing a unitary one-piece plastic container having a body that is generally symmetric about a vertical axis. The body includes at least two rows of panels disposed circumferentially around the body, the panels having central portions that are sufficiently flexible to be dimensionally responsive to changes in pressure within the container. At least one row of the panels has a horizontal width exceeding the vertical height, thus being laterally elongate and having a height/width aspect ratio of less than one. The laterally elongate panels can have a perimeter that is generally rectangular, ellipsoidal, or otherwise elongated in the horizontal direction. The pressure responsive central portion of each laterally elongate panel can be a smooth outwardly projecting dome having a variety of shapes. The edges of the dome can be at the root of a generally radially projecting wall defining the margins of the panel.  
         [0012]     Adjacent rows of panels can be separated from each other by a circumferential ring element of the body side wall joined smoothly to the generally radial projecting walls defining the upper and lower margins of the panels in the adjacent rows. Adjacent panels of each row can be separated from each other by generally vertical posts or lands that have outer surfaces continuous at least at one end with a circumferential ring element. The posts separating the laterally elongate panels in one row can be aligned with the centers of the panels in an adjacent row to achieve a staggered alignment of panels. The side wall of a container can include rows of pressure responsive panels all of which are exclusively laterally elongate. Alternatively, the laterally elongated pressure responsive panels can be included as only a single row adjacent at least one other row of panels having a height/width aspect ratio of at least one.  
         [0013]     The side wall configuration achieved by the incorporation of the laterally elongate pressure responsive panels exhibits exceptionally stable geometry from manufacture through typical hot-fill conditions and subsequent storage despite the use of a modest amount of polymer to form the container. The scope of the containers that can be constructed with side wall of the present invention will become more apparent from the following description and accompanying drawings detailing illustrative examples of the present invention. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. Moreover, in the figures, like referenced numerals designate corresponding parts throughout the different views. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]      FIG. 1  is a side elevation view of a molded polymeric container of the present invention including a plurality of rows of laterally elongated pressure responsive panels.  
         [0015]      FIG. 2  is a sectional view taken along line  2 - 2  in  FIG. 1 .  
         [0016]      FIG. 3  is a sectional view taken along line  3 - 3  in  FIG. 1 .  
         [0017]      FIG. 4  is a perspective view of another molded polymeric container of the present invention including a plurality of rows of pressure responsive panels, only one of which contains laterally elongated pressure responsive panels.  
         [0018]      FIG. 5  is a side elevation view of another molded polymeric container of the present invention including a plurality of rows of pressure responsive panels, only one of which contains laterally elongated pressure responsive panels.  
         [0019]      FIG. 6  is a detail side elevation view of a portion of another molded polymeric container of the present invention including a plurality of rows of laterally elongate pressure responsive panels having central domed portions which are generally saddle shaped. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0020]     A container  10  of the present invention is shown in  FIG. 1  to be generally symmetric about a vertical axis Y, and has an open mouth  12  surrounded by a lip  14  intended to cooperate with a cap, not shown, to seal the container and contents. A cap-engaging finish  16  is located below the lip  14 , which is illustrated to have the form of a spiral thread  18 . The particular form of the finish  16  can be varied to include a range of thread styles or even be replaced with any number of non-threaded finishes designed to accept a crown type or other cap. A pilfer ring  20  can be located immediately below the finish  16  to engage a pilfer-indicating band of a cap. A support ring  22  can be provided below the pilfer ring  20  that facilitates handling of the container  10  as well as the handling of the parison or preform from which the container  10  is formed. A neck portion  24  is located immediately below the support ring.  
         [0021]     A shoulder portion  26  extends outward and downward from a lower margin of the neck portion  24 . The shoulder portion  26  can include an indented hoop ring  28  to provide added strength to the container  10 . A bumper ring  30  can be provided at a lower margin of the shoulder portion  26  that can define the maximum radius R of the container sidewall  32  measured from the axis Y. A lower margin of the bumper ring  30  can also define the upper margin  34  of a label receiving portion  36  that is intended to receive a separate label, not shown. The label can be a sheet of plastic, paper, or other similar material of suitable dimension that can surround the entire sidewall  32  of the container  10 . The label typically covers the container  10  from the upper margin  34  down to the lower margin  38  of the label receiving portion  36 . The label receiving portion  36  can also include one or more reinforcing hoop rings  40 . The hoop rings  40  can be circumferentially continuous such as upper hoop ring  39  or can be discontinuous such as lower hoop ring  41 . A plurality of vacuum compensation panels  42  can also be provided within the label receiving portion  36  of the sidewall  32 . A convex heal portion  44  extends downward from the container sidewall  32  generally to an annular contact ring  46  that supports the container  10  with respect to any underlying surface. The annular contact ring  46  can include or be replaced by a plurality of downward projections, not shown, forming discrete feet upon which the container  10  can stand upon any underlying surface.  
         [0022]     The vacuum compensation panels  42  are arranged in a plurality of circumferential rows  44   a ,  44   b ,  44   c , etc. At least one of the rows  44  contains vacuum compensation panels  42 ′ that have a horizontal width W that exceeds the vertical height H so that the panels  42 ′ appear to be laterally elongated as shown in  FIG. 1 . While the panels  42 ′ appear in  FIG. 1  as generally rectangular, it will be appreciated that other laterally elongated shapes are possible such as elliptical. A circumferential ring element  46  separates each adjacent pair of circumferential rows  44  of panels  42 . Vertical posts  48  separate adjacent panels  42  within each row  44 . Edges  50  and  52  of the circumferential ring elements  46  and vertical posts  48  can respectively define the vertical and horizontal margins of the vacuum compensation panels  42 . The outermost surfaces  54  and  56  of the circumferential ring elements  46  and vertical posts  48 , respectively, can form a smoothly continuous cylindrical surface  58  situated at radius R′ from the Y axis as shown in  FIG. 2 , which is a horizontal cross-section of the container  10 . R′ is generally only slightly smaller than R.  
         [0023]     The vacuum compensation panels  42 ′ can be seen in horizontal cross-section in  FIG. 2  to have a smooth outwardly projecting dome  60 , which can be defined by a radius line R 1  having a center of radius  62  situated between the axis Y and the cylindrical surface  58 . The edges  64  of the dome  60  can be at the root of the generally radially projecting wall  66  of the posts  48  defining the lateral margins of the panel  42 ′. The radius R 1  can range considerably in value, from at least about 0.2 to about 2 times the size of the radius R′ of the surface  58  of the label receiving portion  36 . The variation of the radius R 1  can occur within each dome  60  so that the curve as seen in  FIG. 2  can be elliptical, oval, or otherwise generally smoothly outwardly bulging as well as circular.  
         [0024]     The smooth outwardly projecting dome  60  of the vacuum compensation panels  42 ′ can also be seen in vertical cross-section in  FIG. 3  to be defined by a radius line R 2  having a center of radius  68 . The radius R 2  can also range considerably in value, from at least about 0.2 to about 2 times the size of the radius R′ of the surface  58  of the label receiving portion  36 . The edges  70  of the dome  60  can be at the root of the generally radially projecting wall  72  of the circumferential ring elements  46  defining the elevational margins of the panel  42 ′. The radii R 1  and R 2  need not be of the same size and so the centers of radius  62  and  68  need not be coincident, however they can be. The centers of radius  62  and  68  can be located on a radius line from the Y axis passing through the center of the panel  42 ′.  
         [0025]     Another molded polymeric container  10 ′ is shown in  FIG. 4  to have many of the features of the previously described container  10  including a side wall  32  that includes a plurality of rows  44  of pressure responsive vacuum compensation panels  42 . Only one of the rows  44   b  contains laterally elongated pressure responsive panels  42 ′ of the character described above. The panels  42  in row  44   a  are shown to include a cylindrical wall segment  74  inset with respect to the side wall  32  by a distance determined by the radial dimension of the edge  76 . A central island  78  can be provided in the wall segment  74  to provide additional support for any surrounding label. A circumferential ring element  46  separates row  44   a  from row  44   b  while vertical posts  48  separate the panels  42  within each row  44 . The vertical posts  48  separating the panels  42 ′ are shown to be vertically aligned with the central island  78  within the wall segment  74  of panel  42 . As in  FIG. 1 , the outermost surfaces  54  and  56  of the circumferential ring elements  46  and vertical posts  48 , respectively, can form a smoothly continuous cylindrical surface  58  situated at radius R′ from the Y axis.  
         [0026]     Yet another molded polymeric container  10 ″ is shown in  FIG. 5  to have many of the features of the previously described containers  10  and  10 ′ including a side wall  32  that includes a plurality of rows  44  of laterally elongated pressure responsive vacuum compensation panels  42 ′ and  42 ″. The panels  42 ′ in rows  44   a  and  44   c  include corners defined by a smaller corner radius  80  while the panels  42 ″ include corners defined by a somewhat larger corner radius  82  so as to appear more elliptical-like with a horizontal axis that is greater in length that the vertical axis. The panels  42 ′ and  42 ″ within each row  44  are separated from each other by vertical posts  48  that extend continuously between the upper hoop ring  39  and the lower hoop ring  41 . As in  FIGS. 1 and 4 , the outermost surfaces  54  and  56  of the circumferential ring elements  46  and vertical posts  48 , respectively, can form a smoothly continuous cylindrical surface  58  situated at radius R′ from the Y axis.  
         [0027]     The curves generating the smooth surface of the domes  60  can be even more complex curves generated from a series of radii R 1  and R 2  rather than merely one or two radii.  FIG. 6  is a close-up detail view of a variation of the label receiving portion  36  of the container  10  wherein the domes  60  are formed by a complex series of curves to achieve a generally saddle shape. That is, a vertical mid-line  84  of the domes  60  seen in  FIG. 6  has a very large radius, almost linear, central portion  86  blended with a very small radius upper and lower margin  88 . A typical vertical section line  90  on either side of the vertical mid-line  84  reveals a large radius but inwardly curving central portion  92  that is blended again to very small radius upper and lower margins  88 . A horizontal mid-line  94  of the domes  60  seen in  FIG. 6  has a central portion with a radius that is somewhat smaller than radius R′ of the surface  58  blended with much smaller radius lateral edges  96 . The total appearance of the domes  60  seen in  FIG. 6  is one that includes both convex and concave elements, which together appear as four rounded corner protrusions  98  joined together by a smooth saddle shaped surface  100 , which can exhibit a wide range of pressure/vacuum compensation characteristics.  
         [0028]     The containers  10 ,  10 ′, and  10 ″ are intended to show but not exhaust the variations in structure that are possible using the laterally elongated pressure responsive vacuum compensation panels  42  of the present invention. The configurations achievable by the incorporation of the laterally elongate pressure responsive panels  42  exhibit exceptionally stable geometry from manufacture through typical hot-fill conditions and subsequent storage despite the use of a modest amount of polymer to form the containers  10 . The various side walls  32  provide superior label support, added top load capability, and very favorable handling characteristics even when opened. Thus, the foregoing description the embodiments shown in the Figures should be regarded as merely illustrative rather than limiting, and the following claims, including all equivalents, are intended to define the spirit and scope of this invention.