Patent Publication Number: US-9834359-B2

Title: Vacuum base for container

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is a U.S. National Phase Application under 35 U.S.C. 371 of International Application No. PCT/US2014/017424 filed on Feb. 20, 2014 and published as WO 2015/126404 A1 on Aug. 27, 2015. The entire disclosure of the above application is incorporated herein by reference. 
     FIELD 
     The present disclosure relates to a vacuum base for a container. 
     BACKGROUND 
     This section provides background information related to the present disclosure, which is not necessarily prior art. 
     As a result of environmental and other concerns, plastic containers, more specifically polyester and even more specifically polyethylene terephthalate (PET) containers, are now being used more than ever to package numerous commodities previously packaged in glass containers. Manufacturers and fillers, as well as consumers, have recognized that PET containers are lightweight, inexpensive, recyclable and manufacturable in large quantities. 
     Manufacturers currently supply PET containers for various liquid commodities, such as juice and isotonic beverages. Suppliers often fill these liquid products into the containers while the liquid product is at an elevated temperature, typically between 68° C.-96° C. (155° F.-205° F.) and usually at approximately 85° C. (185° F.). When packaged in this manner, the hot temperature of the liquid commodity sterilizes the container at the time of filling. The bottling industry refers to this process as hot filling, and containers designed to withstand the process as hot-fill or heat-set containers. 
     The hot filling process is acceptable for commodities having a high acid content, but not generally acceptable for non-high acid content commodities. Nonetheless, manufacturers and fillers of non-high acid content commodities desire to supply their commodities in PET containers as well. For non-high acid commodities, pasteurization and retort are the preferred sterilization processes. Pasteurization and retort both present a challenge for manufactures of PET containers in that heat-set containers cannot withstand the temperature and time demands required of pasteurization and retort. 
     Pasteurization and retort are both processes for cooking or sterilizing the contents of a container after filling. Both processes include the heating of the contents of the container to a specified temperature, usually above approximately 70° C. (approximately 155° F.), for a specified length of time (20-60 minutes). Retort differs from pasteurization in that retort uses higher temperatures to sterilize the container and cook its contents. Retort also applies elevated air pressure externally to the container to counteract pressure inside the container. The pressure applied externally to the container is necessary because a hot water bath is often used and the overpressure keeps the water, as well as the liquid in the contents of the container, in liquid form, above their respective boiling point temperatures. 
     PET is a crystallizable polymer, meaning that it is available in an amorphous form or a semi-crystalline form. The ability of a PET container to maintain its material integrity relates to the percentage of the PET container in crystalline form, also known as the “crystallinity” of the PET container. The following equation defines the percentage of crystallinity as a volume fraction: 
               %   ⁢           ⁢   Crystallinity     =         ρ   -     ρ   α           ρ   c     -     ρ   α         ×   100           
where ρ is the density of the PET material; ρ α  is the density of pure amorphous PET material (1.333 g/cc); and ρ c  is the density of pure crystalline material (1.455 g/cc).
 
     Container manufactures use mechanical processing and thermal processing to increase the PET polymer crystallinity of a container. Mechanical processing involves orienting the amorphous material to achieve strain hardening. This processing commonly involves stretching a PET preform along a longitudinal axis and expanding the PET preform along a transverse or radial axis to form a PET container. The combination promotes what manufacturers define as biaxial orientation of the molecular structure in the container. Manufacturers of PET containers currently use mechanical processing to produce PET containers having approximately 20% crystallinity in the container&#39;s sidewall. 
     Thermal processing involves heating the material (either amorphous or semi-crystalline) to promote crystal growth. On amorphous material, thermal processing of PET material results in a spherulitic morphology that interferes with the transmission of light. In other words, the resulting crystalline material is opaque, and thus, generally undesirable. Used after mechanical processing, however, thermal processing results in higher crystallinity and excellent clarity for those portions of the container having biaxial molecular orientation. The thermal processing of an oriented PET container, which is known as heat setting, typically includes blow molding a PET preform against a mold heated to a temperature of approximately 120° C.-130° C. (approximately 248° F.-266° F.), and holding the blown container against the heated mold for approximately three (3) seconds. Manufacturers of PET juice bottles, which must be hot-filled at approximately 85° C. (185° F.), currently use heat setting to produce PET bottles having an overall crystallinity in the range of approximately 25%-35%. 
     After being hot-filled, the heat-set containers are capped and allowed to reside at generally the filling temperature for approximately five (5) minutes at which point the container, along with the product, is then actively cooled prior to transferring to labeling, packaging, and shipping operations. The cooling reduces the volume of the liquid in the container. This product shrinkage phenomenon results in the creation of a vacuum within the container. Generally, vacuum pressures within the container range from 1-300 mm Hg less than atmospheric pressure (i.e., 759 mm Hg-460 mm Hg). If not controlled or otherwise accommodated, these vacuum pressures result in deformation of the container, which leads to either an aesthetically unacceptable container or one that is unstable. 
     In many instances, container weight is correlated to the amount of the final vacuum present in the container after this fill, cap and cool down procedure, that is, the container is made relatively heavy to accommodate vacuum related forces. Similarly, reducing container weight, i.e., “lightweighting” the container, while providing a significant cost savings from a material standpoint, requires a reduction in the amount of the final vacuum. Typically, the amount of the final vacuum can be reduced through various processing options such as the use of nitrogen dosing technology, minimize headspace or reduce fill temperature. One drawback with the use of nitrogen dosing technology however is that the maximum line speeds achievable with the current technology is limited to roughly 200 containers per minute. Such slower line speeds are seldom acceptable. Additionally, the dosing consistency is not yet at a technological level to achieve efficient operations. Minimizing headspace requires more precession during filling, again resulting in slower line speeds. Reducing fill temperature is equally disadvantageous as it limits the type of commodity suitable for the container. 
     Typically, container manufacturers accommodate vacuum pressures by incorporating structures in the container sidewall. Container manufacturers commonly refer to these structures as vacuum panels. Traditionally, these paneled areas have been semi-rigid by design, unable to accommodate the high levels of vacuum pressures currently generated, particularly in lightweight containers. In some applications, these paneled areas may not be aesthetically pleasing. 
     Development of technology options to achieve an ideal balance of light-weighting and design flexibility are of particular interest. According to the principles of the present teachings, an alternative vacuum absorbing capability is provided within the container base. Traditional hot-fill containers accommodate nearly all vacuum forces within the body (or sidewall) of the container through deflection of the vacuum panels. These containers are typically provided with a rigid base structure that substantially prevents deflection thereof and thus tends to be heavier than the rest of the container. In contrast, Applicants utilize a lightweight base designed to accommodate nearly all vacuum forces. 
     Therefore, an object of the present teachings is to achieve the optimal balance of weight and vacuum performance of both the container body and base. To achieve this, in some embodiments, a hot-fill container is provided that comprises a lightweight, flexible base design that is easily moveable to accommodate vacuum, but does not require a dramatic inversion or snap-through, thus eliminating the need for a heavy sidewall or vacuum panels. Utilizing a lightweight base design to absorb vacuum forces enables an overall light-weighting, design flexibility, and permits use of a smooth, “glass-like,” aesthetically pleasing sidewall, which need not include vacuum panels. 
     SUMMARY 
     This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features. 
     The present teachings provide for a container including a finish, a shoulder portion, a sidewall, and a base portion. The finish defines an opening. The shoulder portion extends from the finish. The sidewall extends from the shoulder portion and defines a volume of the container. The base portion is at an end of the sidewall opposite to the shoulder portion. The base portion includes a primary standing ring and a secondary standing ring. The base portion is movable from an as-blown position to an expanded position and from the expanded position to a retracted position. In the as-blown and retracted positions the primary standing ring is configured to support the container upright. In the expanded position the secondary standing ring is configured to support the container upright. 
     The present teachings further provide for a container including a finish, a shoulder portion, a sidewall, and a base portion. The finish defines an opening. The shoulder portion extends from the finish. The sidewall extends from the shoulder portion and defines a volume of the container. The base portion is at an end of the sidewall opposite to the shoulder portion. The base portion is movable from an as-blown position to an expanded position, and from the expanded position to a retracted position. The base portion includes: a primary standing ring, a central zone, and a secondary standing ring between the primary standing ring and the central zone. The central zone is configured to move along a longitudinal axis of the container without flexing as the base portion moves from the as-blown position to the expanded position, and from the expanded position to the retracted position. In the as-blown and the retracted positions the primary standing ring is configured to support the container upright. In the expanded position the secondary standing ring extends out from within the container and beyond the primary standing ring in order to support the container upright. 
     The present teachings also provide for a container including a finish, a shoulder portion, a sidewall, a base portion, and a closure. The finish defines an opening. The shoulder portion extends from the finish. The sidewall extends from the shoulder portion and defines a volume of the container. The base portion is at an end of the sidewall opposite to the shoulder portion. The base portion is movable from an as-blown position to an expanded position, and from the expanded position to a retracted position. The base portion includes a primary standing ring, a central zone, and a secondary standing ring between the primary standing ring and the central zone. The closure is configured to couple with the finish to seal the container closed. The closure may include a vacuum seal indicator. The central zone is configured to move along a longitudinal axis of the container as the base portion moves from the as-blown position to the expanded position, and from the expanded position to the retracted position. In the as-blown and the retracted positions the primary standing ring is configured to support the container upright. In the expanded position the secondary standing ring extends out from within the container and beyond the primary standing ring in order to support the container upright. 
     Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary 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 illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure. 
         FIG. 1  is a side view of a container according to the present teachings; 
         FIG. 2  is a perspective view of a base portion of the container of  FIG. 1 ; 
         FIG. 3  is a bottom view of the base portion of the container of  FIG. 1 ; 
         FIG. 4  is a cross-sectional view taken along line  4 - 4  of  FIG. 3 ; 
         FIG. 5  illustrates movement of the base portion of the container of  FIG. 1  from an as-blown position to an extended position; 
         FIG. 6  illustrates the base portion of the container of  FIG. 1  in the as-blown position C, in a retracted position the base portion is at E 1 , E 2 , or at any point therebetween; 
         FIG. 7  is a perspective view illustrating the container of  FIG. 1  with another container stacked thereon, the container of  FIG. 1  has a modified finish and includes a closure; 
         FIG. 8  is a cross-sectional view taken along line  8 - 8  of  FIG. 7 ; 
         FIG. 9  is a graph illustrating displacement of the base portion of the container of  FIG. 1  versus vacuum pressure; and 
         FIG. 10  is a graph illustrating displacement of the base portion of a prior art container versus vacuum pressure. 
     
    
    
     Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. 
     DETAILED DESCRIPTION 
     Example embodiments will now be described more fully with reference to the accompanying drawings. 
     With initial reference to  FIG. 1 , a container according to the present teachings is generally illustrated at reference numeral  10 . The container  10  generally includes a body portion  12 , a shoulder portion  14 , a finish  16 , and a base portion  18 . 
     The body portion  12  includes a sidewall  22 , which is cylindrical or generally cylindrical, and defines a volume  24  of the container  10 . The sidewall  22  is generally smooth and without vacuum panels, which advantageously provides the container  10  with a “glass-like” appearance. Between the body portion  12  and the base portion  18  is a first recessed ring  26 . Between the body portion  12  and the shoulder portion  14  is a second recessed ring  28 . 
     The shoulder portion  14  extends from the second recessed ring  28  towards the finish  16 . The shoulder portion  14  includes an outer diameter portion  30 , and a tapered surface  32 . The tapered surface  32  extends from the outer diameter portion  30  towards the finish  16 , and is tapered such that the tapered surface  32  has a progressively smaller diameter as it extends away from the outer diameter portion  30 . The tapered surface  32  extends from the outer diameter portion to neck  34 . 
     The finish  16  extends from the neck  34  and includes a first annular rib  36  and a second annular rib  38 . The first annular rib  36  is between the second annular rib  38  and the neck  34 . Each of the first annular rib  36  and the second annular rib  38  extend outward beyond an annular sidewall  40  of the finish  16 . 
     Extending outward from the annular sidewall  40  are threads  42 . The threads  42  are configured to cooperate with any suitable closure in order to close the container  10  by covering an opening defined by the finish  16 , which leads to the volume  24 . The annular sidewall  40  extends to an upper end  44  of the container  10  at which the opening is defined. The upper end  44  is opposite to a base end  46  of the container  10  at the base portion  18 . The finish  16  can be any suitable finish, such as a wide-mouth blow trim finish of any suitable size, such as about 43 mm or greater, or an injected finish of about 43 mm or smaller, for example. 
     The container  10  can be any suitable container, such as a blow-molded, biaxially oriented container with a unitary construction made from a single- or multi-layer material. An exemplary stretch-molding, heat-setting process for making the container  10  generally includes manufacture of a preform (not illustrated) of a suitable polyester material, such as a polyethylene terephalate (PET), having a shape known to those skilled in the art as being similar to a test-tube with a generally cylindrical cross-section and a length typically about fifty percent (50%) that of a height of the container  10 . 
     A machine (not illustrated) places the preform heated to a temperature between approximately 190° F. to 250° F. (approximately 88° C. to 121° C.) into a mold cavity having a shape similar to that of the container  10 . The mold cavity is heated to a temperature between approximately 250° F. to 350° F. (approximately 121° C. to 177° C.). A stretch rod apparatus (not illustrated) stretches or extends the heated preform within the mold cavity to a length approximately that of the container  10  thereby molecularly orienting the polyester material in an axial direction generally corresponding with the longitudinal axis A of the container  10 . When the stretch rod extends the preform, air with a pressure between 300 PSI to 600 PSI (2.07 MPa to 4.14 MPa) assists in extending the preform in the axial direction and expanding the preform in a circumferential or hoop direction thereby substantially conforming the polyester material to the shape of the mold cavity and further molecularly orienting the polyester material in a direction generally perpendicular to the axial direction, thus establishing the biaxial molecular orientation of the polyester material in most of the container. 
     Typically, material with the finish  16  and a sub-portion of the base portion  18  are not substantially molecularly oriented. The pressurized air holds the mostly biaxial molecularly oriented polyester material against the mold cavity for a period of approximately two to five seconds before removal of the container from the mold cavity. To achieve appropriate material distribution within the base portion  18 , an additional stretch-molding step substantially as taught by U.S. Pat. No. 6,277,321, which is incorporated herein by reference, may be used. Alternatively, other manufacturing methods using other conventional thermoplastic materials including, for example, high density polyethylene, polypropylene, polyethylene naphthalate (PEN), a PET/PEN blend or copolymer, and various multi-layer structures may be used to manufacture the container  10 . 
     For hot-fill bottling applications, bottlers generally fill the container  10  with a liquid or product at an elevated temperature between approximately 195° F. to 205° F. (approximately 90.5° C. to 96° C.) and seal the container  10  with a closure before cooling. As the sealed container  10  cools, a vacuum, or negative pressure, forms inside causing the container  10  to change shape, particularly the base portion  18  as described herein. In addition, the container  10  may be suitable for other high-temperature pasteurization or retort filling processes, or other thermal processes as well. 
     With continued reference to  FIG. 1 , and additional reference to  FIGS. 2-5 , the base portion  18  will now be described in detail, as well as movement of the base portion  18  in response to temperatures and pressures experienced by the container  10  during hot-filling of the container  10 .  FIGS. 1-4  illustrate the base portion  18  in an “as-blown” configuration approximately 72 hours after having been formed, and having been stored at normal conditions.  FIG. 5  illustrates the as-blown orientation of the base portion  18  at C.  FIG. 5  also illustrates the base portion  18  in an extended position and orientation at D, which is described in further detail herein. 
     The base portion  18  generally includes a primary standing ring  110  at an outer diameter thereof. At an axial center  112  of the base portion  18  is a gate area  114 , which is generally circular. The longitudinal axis A of the container  10  extends through the axial center  112 . Extending from the axial center  112  and the gate area  114  is a center surface  116 . From the gate area  114 , the center surface  116  can extend inward in the direction of the body portion  12  and thus away from the base end  46 , as illustrated in  FIG. 5 . 
     A side surface  118  extends from the center surface  116  towards the base end  46 . The side surface  118  is angled such that it slopes away from the longitudinal axis A as the side surface  118  extends in the direction of the base end  46 . As illustrated in  FIGS. 2-4 , the side surface  118  includes ribbed portions  120 , which are recessed within the side surface  118 . 
     The side surface  118  extends from the center surface  116  to generally an inwardly extending portion  122 . With respect to an outer side of the base portion  18 , the inwardly extending portion  122  is generally concave. The center surface  116 , the side surface  118 , and the inwardly extending portion  122  (or at least a portion of the inwardly extending portion  122 ) generally define a central zone B of the base portion  18 , as illustrated in  FIGS. 4 and 5 . The central zone B has a planar area that is about 18% to about 28% of a total planar area of the base portion  18  as measured across the standing ring  110  along line T, which extends through the longitudinal axis A. For example, the central zone B can have a planar area that is about 23% of the total planar area of the base portion  18  as measured across the standing ring  110  along line T. 
     Surrounding the central zone B is an outer zone B′ of the base portion  18 . The outer zone B′ includes a convex portion  124  extending from the inwardly extending portion  122 . The convex portion  124  is convex with respect to an outer surface of the base portion  18 . The convex portion  124  provides a secondary standing ring/surface, as further described herein. In some instances, the convex portion  124  is thus also referred to herein as secondary standing ring/surface  124 . 
     A generally planar portion  126  extends from the convex portion  124 . From the convex portion  124  the generally planar portion  126  extends to a concave portion  128 , which is concave with respect to an outer surface of the base portion  18 . A convex portion  130 , which is convex with respect to an outer surface of the base portion  18 , is spaced apart from the concave portion  128 , and is connected thereto with a generally planar portion  132 . 
     Extending from the convex portion  130  away from the longitudinal axis A is another planar portion  134 . The planar portion  134  extends away from the longitudinal axis A to a concave portion  136 , which is generally concave with respect to an outer surface of the base portion  18 . Extending from the concave portion  136  is a convex portion  138 , which is generally convex with respect to an outer surface of the base portion  18 , and includes the primary standing ring  110 . 
     With particular reference to  FIG. 5 , the primary standing ring  110  is configured to support the container  10  upright on a first standing surface  150  when the base portion  18  is in the as-blown configuration C of  FIG. 5 , which is before the container  10  is filled, such as by hot-filling. When the container  10  is hot-filled, product heated to 195-205° F. (90.5-96° C.) is loaded into the container  10 , and then the finish  16  is quickly capped with a suitable closure, such as the closure  180  of  FIGS. 7 and 8 . Although the closure  180  is illustrated as a metal lug closure (and the finish  16  of  FIGS. 7 and 8  is modified to have internal threads  42 ), the closure  180  can be any suitable closure, such as a threaded plastic closure or a combi closure. 
     In response to receipt of the heated product and an increased pressure resulting from closing the container  10  with the closure  180 , the base portion  18  moves outward along the longitudinal axis A to the extended position D of  FIG. 5 . The central zone B does not flex as it moves along the longitudinal axis A to the extended position D. In contrast, portions of the base portion  18  in the outer zone B′ do flex. For example, the secondary standing ring  124  flexes outward beyond the primary standing ring  110  and the first standing surface  150 . The secondary standing ring  124  is configured to support the container  10  upright on a second standing surface  152  when the base portion  18  moves to the extended position D. When transitioning from the as-blown position C to the extended position D and the retracted position E 1 -E 2  (described herein), any tilting experienced by the container  10 , such as at the base portion  18 , will typically be less than about 2° (such as less than about 0.5°) as measured between longitudinal axis A and axis A′ of  FIG. 5 . 
     As the base portion  18  moves from the as-blown position C to the extended position D, the side surface  118  of the central zone B does not flex, but merely moves in a direction generally parallel to the longitudinal axis A. Therefore, angle A 1  of the side surface  118  relative to the longitudinal axis A remains constant as the base portion  18  moves from the as-blown position C to the extended position D. In contrast, angle A 2  of planar portion  126  relative to the longitudinal axis A, and angle A 3  of planar surface  134  relative to the longitudinal axis A, both decrease as the base portion  18  moves from the as-blown position C to the extended position D. Central zone B includes the ribbed portions  120 , which act as strengthening ribs to enhance the rigidity of the central zone B. 
     As the base portion  18  moves from the as-blown position C to the extended position D, various bend radii of the outer zone B′ change in response to flexing of the outer zone B′ generally outward. As illustrated in  FIG. 5 , bend radii R 1 -R 5  change as follows: R 1  increases (R 1  is generally at the primary standing ring  110 ); R 2  decreases (R 2  is generally at the concave portion  136 ); R 3  increases (R 3  is generally at the convex portion  130 ); R 4  increases (R 4  is generally at the concave portion  128 ); and R 5  decreases to provide the secondary standing ring (R 5  is generally at the convex portion  124 ). As the central zone B moves from the as-blown position C to the extended position D, distance D 1  measured from the gate area  114  to the first standing surface  150  decreases. 
     Movement of the base portion  18  from the as-blown position C to the extended position D in response to increased pressure can be summarized as follows: 
     
       
         
           
               
               
               
             
               
                   
                   
               
             
            
               
                   
                 R 1   
                 Increase 
               
               
                   
                 R 2   
                 Decrease 
               
               
                   
                 R 3   
                 Increase 
               
               
                   
                 R 4   
                 Increase 
               
               
                   
                 R 5   
                 Decrease 
               
               
                   
                 A 1   
                 Constant/Generally 
               
               
                   
                   
                 Constant 
               
               
                   
                 A 2   
                 Decrease 
               
               
                   
                 A 3   
                 Decrease 
               
               
                   
                 D 1   
                 Decrease 
               
               
                   
                   
               
            
           
         
       
     
     Exemplary dimensions of the base portion  18  in the as-blown position C as compared to the extended position D are set forth below: 
     
       
         
           
               
               
               
               
             
               
                   
               
               
                   
                   
                 Exemplary 
                   
               
               
                   
                 Exemplary As-Blown 
                 Extended 
               
               
                 Feature 
                 Position C 
                 Position D 
                 Change 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 R 3   
                 0.097 
                 mm 
                 0.11 
                 mm 
                 +0.013 
                 mm 
               
               
                 R 5   
                 0.156 
                 mm 
                 0.139 
                 mm 
                 −0.017 
                 mm 
               
            
           
           
               
               
               
               
            
               
                 A 1   
                 37° 
                 37° 
                  0° 
               
               
                 A 2   
                 74° 
                 57° 
                 −17° 
               
               
                 A 3   
                 101°  
                 63° 
                 −38° 
               
            
           
           
               
               
               
               
               
               
               
            
               
                 D 1   
                 0.6 
                 mm 
                 0.25 
                 mm 
                 −0.35 
                 mm 
               
               
                   
               
            
           
         
       
     
     As the hot-filled product cools, temperature of the base portion  18  decreases, and an internal vacuum is created within the container. As a result, the base portion  18  moves from the extended position D to retracted position E 1 -E 2 , which includes position E 1 , E 2 , or any position between E 1  and E 2  illustrated in  FIG. 6 . For reference purposes,  FIG. 6  also illustrates the as-blown position C. The base portion  18  may move, for example, to position E 1 , which is beneath position C, to position E 2 , which is above and beyond position C, or to any point therebetween. 
     As the base portion  18  moves from the extended position D to the retracted position E 1 -E 2 , the central zone B moves along the longitudinal axis A in the direction of the finish  16 , but does not substantially flex. Central zone B includes the ribbed portions  120 , which act as strengthening ribs to enhance the rigidity of the central zone B. 
     Most of the flexing of the base portion  18  occurs at the outer zone B′. Therefore, angle A 1  remains constant, or generally constant, as the base portion  18  moves to the retracted position E 1 -E 2 . Angles A 2  and A 3  increase, however, as the base portion  18  moves to the retracted position E 1 -E 2 . As explained above, in the retracted position E 1 -E 2  the base portion  18  can be at E 1 , E 2 , or at any point therebetween. Thus for ease of reference in  FIG. 6 , angles A 1 , A 2 , and A 3  are each measured relative to illustrated position C, which is generally between E 1  and E 2 . 
     With respect to the bend radii R 1 -R 5 , they change as follows, which is generally opposite to the change that occurs during movement of the base portion  18  from the as-blown position C to the extended position D described above: R 1  decreases; R 2  increases; R 3  decreases; R 4  decreases; and R 5  increases. The distance that the gate area  114  is from the first standing surface  150  increases from D 1  in the as-blown position C to D 2  in the retracted position E 1 -E 2 . In the retracted position E 1 -E 2 , the base portion  18  extends an additional four millimeters, for example, into the container  10  as compared to the as-blown position C. 
     The primary standing ring  110  also moves slightly inward in the direction of the finish  16  to provide a third and final standing surface  154  for the container  10 . In general and as illustrated in  FIG. 6 , in the retracted position E 1 -E 2  the base portion  18  is recessed within the container  10  so that D 3 , measured between the standing surface  154  and about R 5  is greater than 0, and thus R 5  is above 154. Movement of the base portion  18  from the extended position D to the retracted position E 1 -E 2  due to vacuum response forces can be summarized as follows: 
     
       
         
           
               
               
               
             
               
                   
                   
               
             
            
               
                   
                 R 1   
                 Decrease 
               
               
                   
                 R 2   
                 Increase 
               
               
                   
                 R 3   
                 Decrease 
               
               
                   
                 R 4   
                 Decrease 
               
               
                   
                 R 5   
                 Increase 
               
               
                   
                 A 1   
                 Constant/Generally 
               
               
                   
                   
                 Constant 
               
               
                   
                 A 2   
                 Increase 
               
               
                   
                 A 3   
                 Increase 
               
               
                   
                 D 1   
                 Increase 
               
               
                   
                   
               
            
           
         
       
     
     Exemplary dimensions of the base portion  18  in the as-blown position C as compared to the retracted position E 1 -E 2  are set forth below: 
     
       
         
           
               
               
               
               
               
               
             
               
                   
                   
               
               
                   
                   
                   
                   
                 Exemplary 
                   
               
               
                   
                   
                   
                 Exemplary as-Blown 
                 Retracted 
               
               
                   
                 Feature 
                   
                 Position C 
                 Position E1-E2 
                 Change 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                 R 3   
                 0.097 
                 mm 
                 0.069 
                 mm 
                 −0.028 
               
               
                   
                 R 5   
                 0.156 
                 mm 
                 0.192 
                 mm 
                 +0.036 
               
            
           
           
               
               
               
               
               
            
               
                   
                 A 1   
                 37° 
                 37° 
                  0° 
               
               
                   
                 A 2   
                 74° 
                 76° 
                 +2° 
               
               
                   
                 A 3   
                 101°  
                 106°  
                 +5° 
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                 D 1   
                 0.6 
                 mm 
                 0.6 
                 mm 
                 0 
               
               
                   
                   
               
            
           
         
       
     
     Exemplary differences between the pressure response of extended position D and the vacuum response of the retracted position E 1 -E 2  are set forth below: 
     
       
         
           
               
               
               
               
               
             
               
                   
               
               
                   
                 Exemplary 
                 Exemplary 
                   
                   
               
               
                   
                 Pressure 
                 Vacuum 
               
               
                 Feature 
                 Response 
                 Response 
                 Change 
                 Result 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 R 3   
                 0.11 
                 mm 
                 0.069 
                 mm 
                 −0.041 
                 Decrease 
               
               
                 R 5   
                 0.139 
                 mm 
                 0.192 
                 mm 
                 +0.053 
                 Increase 
               
            
           
           
               
               
               
               
               
            
               
                 A 1   
                 37° 
                 37° 
                  0° 
                 Equal 
               
               
                 A 2   
                 57° 
                 76° 
                 19° 
                 Increase 
               
               
                 A 3   
                 63° 
                 106°  
                 43° 
                 Increase 
               
            
           
           
               
               
               
               
               
               
               
            
               
                 D 1   
                 0.25 
                 mm 
                 0.6 
                 mm 
                 0.35 mm 
                 Increase 
               
               
                   
               
            
           
         
       
     
     Movement of the base portion  18  from the as-blown position C to the extended position D, and to the retracted position E 1 -E 2  allows the container  10  to respond to the increased temperatures and pressures associated with, for example, hot fill applications, without having to include vacuum absorption features in the sidewall  22 . As a result, the sidewall  22  can have a generally smooth and “glass-like” appearance, as illustrated in  FIG. 1 , for example. Further, no base over-stroke operation is required with the container  10 . When transitioning from the as-blown position to the extended position and retracted position, any tilting experienced by the container  10  is less than about 2 degrees, such as less than about 0.5 degrees measured between the longitudinal axis A and A′. 
     At room temperature, there are between five and 15 inches Hg of residual vacuum in the filled and cooled container. This remaining vacuum is useful when the closure  180  is a metal lug style closure, as illustrated in  FIGS. 7 and 8 . For example, the closure  180  can include a freshness indicator/tamper evident button  182  at a center thereof ( FIG. 8 ). The button  182  is drawn inward when the container is unopened in response to vacuum pressures therein. When the container  10  is opened, the button  182  pops out, typically with an audible sound, which indicates to a consumer that the product inside the container  10  is fresh. Geometry of the base portion  18  can be optimized to work together with the closure  180  and the button  182  thereof in order to ensure that a proper amount of residual vacuum is present within the container  10  for the button  182  to operate properly. 
     With reference to  FIGS. 7 and 8 , the container  10  is illustrated with a second container  10 ′ stacked thereon. The container  10 ′ is similar to the container  10 , and thus features of the container  10 ′ that are in common with the container  10  are illustrated with the same reference numerals, but include the prime (′) symbol. In the retracted position E 1 -E 2 , the base portion  18 ′ of the container  10 ′ provides a stacking surface. Specifically, the generally planar portion  126 ′ of the container  10 ′ provides a standing surface for container  10 ′ atop the closure  180  of the container  10 . The closure  180  of container  10  can be received within the base portion  18 ′ such that generally planar portion  132 ′ of the container  10 ′, which is generally vertical in the retracted position E 1 -E 2  of  FIG. 8 , surrounds the closure  180  in order to securely receive the closure  180  within the base portion  18 ′ and prevent the container  10 ′ from sliding off of the closure  180 . 
       FIG. 9  is a graph of performance of an exemplary container  10  including base portion  18  according to the present teachings showing displacement of the sidewall  22  at various vacuum pressures.  FIG. 9  is a similar graph of a prior art container. As illustrated in  FIG. 9 , the prior art container experiences failure or an undesirable response at a sidewall thereof at about only 11.32 PSI and after about 72 ml of displacement. In contrast, the container  10  of the present teachings experiences reduced sidewall performance at about 11.55 PSI and after about 125 ml of displacement. 
     The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.