Patent Publication Number: US-2011073559-A1

Title: Hot-fill container having improved label support

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates generally to the field of plastic containers, and more particularly to plastic containers that are designed to accommodate volumetric expansion and contraction such as that inherent to the hot-fill packaging process or to packaging applications where internal pressurization is anticipated. 
     2. Description of the Related Technology 
     Many products that were previously packaged using glass containers are now being supplied in plastic containers, such as containers that are fabricated from polyesters such as polyethylene terephthalate (PET). 
     PET containers are typically manufactured using the stretch blow molding process. This involves the use of a preform that is injection molded into a shape that facilitates distribution of the plastic material within the preform into the desired final shape of the container. The preform is first heated and then is longitudinally stretched and subsequently inflated within a mold cavity so that it assumes the desired final shape of the container. As the preform is inflated, it takes on the shape of the mold cavity. The polymer solidifies upon contacting the cooler surface of the mold, and the finished hollow container is subsequently ejected from the mold. 
     Hot fill containers are designed to be used with the conventional hot fill process in which a liquid or semi-solid product such as fruit juice, sauce, salsa, jelly or fruit salad is introduced into the container while warm or hot, as appropriate, for sanitary packaging of the product. After filling, such containers undergo significant volumetric shrinkage as a result of the cooling of the product within the sealed container. Hot fill type containers accordingly must be designed to have the capability of accommodating such shrinkage. Typically this has been done by incorporating one or more vacuum panels into the side wall of the container that are designed to flex inwardly as the volume of the product within the container decreases as a result of cooling. Several vacuum panels are typically provided, with integral column structures interposed between the respective vacuum panels. The vacuum panel regions of conventional hot fill containers are usually recessed with respect to the adjacent columns. 
     In many cases, the needs of a manufacturer require that an adhesive or shrink-fit label be secured to the container over the vacuum panels. In order to avoid excessive crinkling or deformation of the label when the container is squeezed or when volumetric expansion or contraction occurs within the container, it is important that the vacuum panels and the container as a whole be designed to provide as much support for the label as possible. In some cases, one or more raised areas are provided within the vacuum panel for improved label support. These are typically referred to as islands. However, even containers having vacuum panels with islands typically have a significant amount of surface area that is not in direct contact with the label. Air gaps accordingly exist between the container and the label. In one conventional container having six vacuum panels that is marketed by the assignee of this invention, the ratio of the surface area under the label that is in direct contact with the label to the surface area under the label that is not in direct contact with the label is about 0.85. This is typical for containers of this type. 
     In terms of design priorities, conventional measures that can be taken to improve label support often have the unwanted effect of reducing the efficacy of the vacuum panels at accommodating volumetric expansion and contraction. The design of such containers is also often influenced by the aesthetic preferences of manufacturers, which in some instances can place limitations of the size of the vacuum panels and on structure for providing label support. 
     A need exists for an improved vacuum panel configuration for a plastic container that achieves optimal label support, vacuum uptake capacity and aesthetics. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an object of the invention to provide an improved vacuum panel configuration for a plastic container that achieves optimal label support, vacuum uptake capacity and aesthetics. 
     In order to achieve the above and other objects of the invention, a plastic container that is adapted for adjustment to internal volumetric changes includes a container body defining an internal space. The container body includes a main body portion having a plurality of vacuum panels disposed about an outer circumference thereof and a corresponding plurality of columns interposed between the vacuum panels. A label covers at least a portion of the vacuum panels and the columns. The label has a first portion having a first surface area that is in contact with the container and a second portion having a second surface area that is not in contact with the container. A ratio of the first surface area to the second surface area is at least 1.0. 
     A plastic container that is adapted for adjustment to internal volumetric changes according to a second aspect of the invention includes a container body defining an internal space. The container body has a main body portion having a plurality of vacuum panels disposed about an outer circumference thereof and a corresponding plurality of columns interposed between the vacuum panels. A label covers at least a portion of the vacuum panels and the columns. At least one of said columns comprises a raised transition portion that is integral with an adjacent vacuum panel. The raised transition portion extends radially outwardly with respect to an adjacent portion of the column, whereby the adjacent vacuum panel is elevated with respect to portions of the column in order to improve label support. 
     These and various other advantages and features of novelty that characterize the invention are pointed out with particularity in the claims annexed hereto and forming a part hereof. However, for a better understanding of the invention, its advantages, and the objects obtained by its use, reference should be made to the drawings which form a further part hereof, and to the accompanying descriptive matter, in which there is illustrated and described a preferred embodiment of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side elevational view of a container that is constructed according to a preferred embodiment of the invention; 
         FIG. 2  is a cross-sectional view taken along lines  2 - 2  in  FIG. 1 ; 
         FIG. 3  is a cross-sectional view taken along lines  3 - 3  in  FIG. 1 ; 
         FIG. 4  is a diagrammatical depiction of a label secured to the container as it is shown in  FIG. 2 ; and 
         FIG. 5  is a diagrammatical depiction of a label secured to the container as is shown in  FIG. 3 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S) 
     Referring now to the drawings, wherein like reference numerals designate corresponding structure throughout the views, and referring in particular to  FIG. 1 , a plastic container  10  that is constructed according to a preferred embodiment of the invention is adapted for adjustment to internal volumetric changes, such as those that typically occur during the hot fill process or for applications in which internal pressurization of the container  10  is anticipated. 
     Container  10  is preferably fabricated from a material such as polyethylene terephthalate (PET) using a conventional reheat stretch blow molding process. It includes a bottom portion  12 , a threaded upper finish portion  14 , a dome or bell portion  16  and a main body portion  18 . The main body portion  18  is preferably substantially cylindrical in shape and has a plurality of vacuum panels  20  disposed about an outer circumference of the main body portion  18 . A corresponding plurality of columns  22  is provided, with each column  22  being interposed between two adjacent vacuum panels  20 . 
     In the preferred embodiment, the vacuum panels  20  have an hourglass shape with relatively wide upper and lower portions and a relatively narrow central portion as viewed in side elevation, and the columns  22  have a complementary bow shape having a relatively wide central portion and relatively narrow upper and lower portions. The vacuum panels  20  and the columns  22  are preferably arranged in a repeating pattern that extends about the entire circumference of the main body portion  18 . 
     The vacuum panels  20  are preferably configured so as to have no island or other raised portion defined therein. Accordingly, the entire surface area of each of the vacuum panels  20  is available for flexion in order to accommodate vacuum uptake during the hot fill process. 
     Each of the vacuum panels  20  is preferably slightly convex as viewed in transverse cross-section as shown in  FIGS. 2 and 3 , with a transverse radius of curvature that is preferably substantially constant longitudinally from the top of the vacuum panel  20  to the bottom of the vacuum panel  20 . 
     As may be seen in  FIGS. 2 and 3 , the main body portion  18  as viewed in any horizontal cross-section includes a maximum outer radius R MAX . As viewed in horizontal cross-section, it will be seen that each of the columns  22  includes a central raised portion  26  that represents the maximum outer radius, a pair of raised transition portions  28  that are integral with an adjacent vacuum panel  20  and a pair of recessed portions  30  that are positioned between the central raised portion  26  and a raised transition portions  28 . Each of the raised transition portions  28  extends radially outwardly with respect to an adjacent portion of the column  22 , namely the recessed portion  30 , so that the adjacent vacuum panel  20  is elevated with respect to portions of the column  22  in order to improve label support. 
     Accordingly, in the preferred embodiment each of the columns  22  has a W-shaped cross-section that provides enhanced label support. Additionally, the W-shaped cross sections of the columns  22  create an accordion effect permitting expansion of the main body portion  18  and additional vacuum uptake capacity together with the vacuum uptake capacity that is provided by the flexible vacuum panels  20 . 
     Each of the vacuum panels  20  further has a maximum depth D VP  with respect to the maximum outer radius R MAX  of the main body portion  18  within the same horizontal cross-section. This represents the maximum depth of the main body portion  18 . Preferably, the maximum depth of the main body portion  18  as expressed as a ratio with respect to the maximum outer radius R MAX  is no greater than about 0.2. More preferably, this ratio is no greater than about 0.1. 
     The recessed portions  30  of the columns  22  have a maximum depth D R , and the raised transition portions  28  have a minimum depth D OT . Preferably, the ratio of D R  to D OT  is within a range of about 1 to about 2. The vacuum panels  20  have a length L VP  and the columns  22  have a length L C  as viewed in horizontal cross-section. 
     Referring briefly to  FIGS. 4 and 5 , it will be seen that container  10  further includes a label  24  that covers at least a portion of both the vacuum panels  20  and the columns  22 . Label  24  preferably extends about an entire circumference of the main body portion  18 . In the preferred embodiment, label  24  covers substantially all of the surface area of the vacuum panels  20  and the columns  22 . 
     Label  24  has a first portion having a first surface area that is in contact with the container  10 , and more specifically the main body portion  18 , and a second portion having a second surface area that is not in direct contact with the main body portion  18 . As may be seen in  FIG. 5 , which is a representation of how the label  24  fits the main body portion  18  of the container  10  as viewed in cross-section along lines  3 - 3  in  FIG. 1 , the label  24  is in direct contact with the main body portion  18  in areas C VP  over the vacuum panels  20  and in areas C C  over a central raised portion  26  of each of the columns  22 . The label  24  is not in direct contact with the main body portion  18  in areas N R  that overlay portions of the raised transition portions  28  and the intermediate recessed portions  30  of the columns  22 . Accordingly, a very high percentage of the label  24  is in direct contact with the main body portion  18 , with only a small air gap between the label  24  and the main body portion  18  existing over the outermost portions of the columns  22 . 
     Preferably, the ratio of the first surface area to the second surface area is at least 1.0. More preferably, the ratio of the first surface area to the second surface area is at least 1.3, and most preferably the ratio of the first surface area to the second surface area is at least 1.6. 
     The main body portion  18  of the container  10  accordingly undergoes very little depth change when squeezed, which minimizes crinkling and the potential for initiation of delamination of the label  24 . 
     It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.