Patent Publication Number: US-9833938-B2

Title: Heat-set container and mold system thereof

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a 371 U.S. National Stage of International Application No. PCT/US2012/053354 filed on Aug. 31, 2012, which claims the benefit of U.S. Provisional Application No. 61/529,289, filed on Aug. 31, 2011. The contents of the above applications are incorporated herein by reference in their entirety. 
    
    
     FIELD 
     This disclosure generally relates to containers for retaining a commodity, such as a solid or liquid commodity. More specifically, this disclosure relates to a container having an optimized base design to provide a balanced vacuum and pressure response, while minimizing container weight. 
     BACKGROUND 
     This section provides background information related to the present disclosure which is not necessarily prior art. This section also provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features. 
     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 supplied in glass containers. Manufacturers and fillers, as well as consumers, have recognized that PET containers are lightweight, inexpensive, recyclable and manufacturable in large quantities. 
     Blow-molded plastic containers have become commonplace in packaging numerous commodities. 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   a           ρ   c     -     ρ   a         )     ×   100           
where ρ is the density of the PET material; ρa is the density of pure amorphous PET material (1.333 g/cc); and ρc is the density of pure crystalline material (1.455 g/cc).
 
     Container manufacturers 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 an injection molded 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 250° F.-350° F. (approximately 121° C.-177° C.), and holding the blown container against the heated mold for approximately two (2) to five (5) seconds. Manufacturers of PET juice bottles, which must be hot-filled at approximately 185° F. (85° C.), currently use heat setting to produce PET bottles having an overall crystallinity in the range of approximately 25%-35%. 
     Unfortunately, with some applications, as PET containers for hot fill applications become lighter in material weight (aka container gram weight), it becomes increasingly difficult to create functional designs that can simultaneously resist fill pressures, absorb vacuum pressures, and withstand top loading forces. According to the principles of the present teachings, the problem of expansion under the pressure caused by the hot fill process is improved by creating unique vacuum/label panel geometry that resists expansion, maintains shape, and shrinks back to approximately the original starting volume due to vacuum generated during the product cooling phase. 
     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. 
     SUMMARY 
     A heat-set container that defines a longitudinal axis is disclosed that includes a finish and a sidewall portion extending from the finish. The container also includes a base portion extending from the sidewall portion and enclosing said sidewall portion to form a volume therein for retaining a commodity. The base portion has a plurality of contact surfaces for supporting the container. The plurality of contact surfaces are spaced away from each other about the longitudinal axis. Also, the container includes a central pushup portion disposed in the base portion and extending generally toward the finish. The central pushup portion is substantially centered on the longitudinal axis, and the central pushup portion is moveable in response to internal vacuum pressure to decrease the volume. 
     A mold system is also disclosed for forming a heat-set container having a central pushup portion disposed in a base portion thereof. The central pushup portion is substantially centered on a longitudinal axis of the container and extends generally toward an interior of the container. The base portion has a plurality of contact surfaces for supporting the container. The plurality of contact surfaces are spaced away from each other about the longitudinal axis. The base portion is bound by a sidewall portion to hold a commodity. The mold system comprises a sidewall system for molding the sidewall portion of the container and a base system for molding the base portion of the container. The base system is operable to form an entirety of the base portion of the container including the central pushup portion and the plurality of contact surfaces. 
    
    
     
       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. 
         FIGS. 1-5  are views illustrating exemplary embodiments of a container with various features of the present teachings, wherein  FIG. 1  is a perspective view,  FIG. 2  is a side view,  FIG. 3  is a front view,  FIG. 4  is a bottom view, and  FIG. 5  is a section view taken along the line  5 - 5  of  FIG. 4 ; 
         FIGS. 6-9  are views illustrating additional exemplary embodiments of a container with various features of the present teachings, wherein  FIG. 6  is a perspective view,  FIG. 7  is a side view,  FIG. 8  is a bottom view, and  FIG. 9  is a section view taken along the line  9 - 9  of  FIG. 8 ; 
         FIGS. 10-13  are views illustrating additional exemplary embodiments of a container with various features of the present teachings, wherein  FIG. 10  is a perspective view,  FIG. 11  is a side view,  FIG. 12  is a bottom view, and  FIG. 13  is a section view taken along the line  13 - 13  of  FIG. 12 ; 
         FIGS. 14-17  are views illustrating additional exemplary embodiments of a container with various features of the present teachings, wherein  FIG. 14  is a perspective view,  FIG. 15  is a side view,  FIG. 16  is a bottom view, and  FIG. 17  is a section view taken along the line  17 - 17  of  FIG. 16 ; 
         FIGS. 18 and 19  are views illustrating additional exemplary embodiments of a container with various features of the present teachings, wherein  FIG. 18  is a bottom view and  FIG. 19  is a section view taken along the line  19 - 19  of  FIG. 18 ; 
         FIGS. 20 and 21  are views illustrating additional exemplary embodiments of a container with various features of the present teachings, wherein  FIG. 20  is a bottom view and  FIG. 21  is a section view taken along the line  21 - 21  of  FIG. 20 ; 
         FIGS. 22 and 23  are views illustrating additional exemplary embodiments of a container with various features of the present teachings, wherein  FIG. 22  is a bottom view and  FIG. 23  is a section view taken along the line  23 - 23  of  FIG. 22 ; 
         FIGS. 24 and 25  are views illustrating additional exemplary embodiments of a container with various features of the present teachings, wherein  FIG. 24  is a bottom view and  FIG. 25  is a section view taken along the line  25 - 25  of  FIG. 24 ; 
         FIGS. 26A and 26B  are section and side views, respectively, of a base portion of a container according to additional exemplary embodiments of the present disclosure; 
         FIGS. 27A and 27B  are section and side views, respectively, of a base portion of a container according to additional exemplary embodiments of the present disclosure; 
         FIGS. 28A and 28B  are front and side views, respectively, of a generally rectangular container according to additional exemplary embodiments of the present disclosure; 
         FIGS. 29A and 29B  are perspective and bottom views, respectively, of a generally cylindrical container according to additional exemplary embodiments of the present disclosure; 
         FIGS. 30A and 30B  are perspective and bottom views, respectively, of a generally cylindrical container according to additional exemplary embodiments of the present disclosure; 
         FIGS. 31A and 31B  are views of additional exemplary embodiments of a container according to the present teachings, wherein  FIG. 31A  is a bottom view and  FIG. 31B  is a section view taken along the line  31 B- 31 B of  FIG. 31A ; 
         FIG. 32  is a perspective view of a mold system suitable for molding the container of the present disclosure; 
         FIGS. 33A-33C  is a series of graphs illustrating the relationship between strap inclination angle and volume displacement, the number of straps and radial strength, and the strap peak angle and volume displacement is a graph illustrating a relationship between dimensions of a strap of the container and a volume displacement of a hot-filled container; 
         FIG. 34  is a schematic section view of a container showing various curving surfaces of a central pushup portion thereof; 
         FIGS. 35A-35D  are schematic bottom views of a central pushup portion of a container according to teachings of the present disclosure; 
         FIG. 36  is a schematic section view of a container showing various shapes for straps thereof; and 
         FIG. 37-39  are schematic bottom views of the container showing various shapes for straps thereof. 
     
    
    
     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. Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. 
     The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms “a”, “an” and “the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “comprising,” “including,” and “having,” are inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed. 
     When an element or layer is referred to as being “on”, “engaged to”, “connected to” or “coupled to” another element or layer, it may be directly on, engaged, connected or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly engaged to”, “directly connected to” or “directly coupled to” another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
     Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as “first,” “second,” and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments. 
     Spatially relative terms, such as “inner,” “outer,” “beneath”, “below”, “lower”, “above”, “upper” and the like, may be used herein for ease of description to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the example term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. 
     This disclosure provides for a container being made of PET and incorporating a base design having an optimized size and shape that resists container loading and pressures caused by hot fill pressure and resultant vacuum, and helps maintain container shape and response. 
     It should be appreciated that the size and specific configuration of the container may not be particularly limiting and, thus, the principles of the present teachings can be applicable to a wide variety of PET container shapes. Therefore, it should be recognized that variations can exist in the present embodiments. That is, it should be appreciated that the teachings of the present disclosure can be used in a wide variety of containers, including rectangular, round, oval, squeezable, recyclable, and the like. 
     As shown in  FIGS. 1-5 , the present teachings provide a plastic, e.g. polyethylene terephthalate (PET), container generally indicated at  10 . The exemplary container  10  can be substantially elongated when viewed from a side and generally cylindrical when viewed from above and/or rectangular in throughout or in cross-sections (which will be discussed in greater detail herein). Those of ordinary skill in the art would appreciate that the following teachings of the present disclosure are applicable to other containers, such as rectangular, triangular, pentagonal, hexagonal, octagonal, polygonal, or square shaped containers, which may have different dimensions and volume capacities. It is also contemplated that other modifications can be made depending on the specific application and environmental requirements. 
     In some embodiments, container  10  has been designed to retain a commodity. The commodity may be in any form such as a solid or semi-solid product. In one example, a commodity may be introduced into the container during a thermal process, typically a hot-fill process. For hot-fill bottling applications, bottlers generally fill the container  10  with a product at an elevated temperature between approximately 155° F. to 205° F. (approximately 68° C. to 96° C.) and seal the container  10  with a closure before cooling. In addition, the plastic container  10  may be suitable for other high-temperature pasteurization or retort filling processes or other thermal processes as well. In another example, the commodity may be introduced into the container under ambient temperatures. 
     As shown in  FIGS. 1-5 , the exemplary plastic container  10  according to the present teachings defines a body  12 , and includes an upper portion  14  having a cylindrical sidewall  18  forming a finish  20 . Integrally formed with the finish  20  and extending downward therefrom is a shoulder portion  22 . The shoulder portion  22  merges into and provides a transition between the finish  20  and a sidewall portion  24 . The sidewall portion  24  extends downward from the shoulder portion  22  to a base portion  28  having a base  30 . In some embodiments, sidewall portion  24  can extend down and nearly abut base  30 , thereby minimizing the overall area of base portion  28  such that there is not a discernable base portion  28  when exemplary container  10  is uprightly-placed on a surface. 
     The exemplary container  10  may also have a neck  23 . The neck  23  may have an extremely short height, that is, becoming a short extension from the finish  20 , or an elongated height, extending between the finish  20  and the shoulder portion  22 . The upper portion  14  can define an opening for filling and dispensing of a commodity stored therein. The container can be a beverage container; however, it should be appreciated that containers having different shapes, such as sidewalls and openings, can be made according to the principles of the present teachings. 
     The finish  20  of the exemplary plastic container  10  may include a threaded region  46  having threads  48 , a lower sealing ridge  50 , and a support ring  51 . The threaded region provides a means for attachment of a similarly threaded closure or cap (not shown). Alternatives may include other suitable devices that engage the finish  20  of the exemplary plastic container  10 , such as a press-fit or snap-fit cap for example. Accordingly, the closure or cap engages the finish  20  to preferably provide a hermetical seal of the exemplary plastic container  10 . The closure or cap is preferably of a plastic or metal material conventional to the closure industry and suitable for subsequent thermal processing. 
     In some embodiments, the container  10  can comprise a lightweight base configuration  100  generally formed in base portion  28 . Base configuration  100  can comprise any one of a number of features that facilitate vacuum response, improve structural integrity, minimize container weight, and/or improve overall performance of container  10 . As discussed herein, base configuration  100  can be used in connection with any container shape, however, by way of illustration, containers having rectangular and cylindrical cross-sections will be examined. The base portion  28  functions to close off the bottom portion of the plastic container  10  to retain a commodity in the container  10 .  FIGS. 1-31B  illustrate a variety of base configurations  100  and base portions  28  as well, as will be discussed. 
     Referring back to  FIGS. 1-5 , the base portion  28  of the plastic container  10 , which extends inward from the body  12 , can comprise one or more contact surfaces  134  and a central portion  136 . In some embodiments, the contact surface(s)  134  is the area of the base portion  28  that contacts a support surface (e.g. shelf, counter, and the like) that in turn supports the container  10 . As such, the contact surface  134  may be a flat surface (an individual flat surface or a collection of separately spaced flat surfaces that each lie within a common plane. The contact surface  134  can also be a line of contact generally circumscribing, continuously or intermittently, the base portion  28 . 
     In the embodiments of  FIGS. 1-5 , the base portion  28  includes four contact surfaces  134 , which are spaced away from each other about the longitudinal axis  150  of the container  10 . Also, in the embodiments shown, the contact surfaces  134  are arranged at the corners of the base portion  28 . However, it will be appreciated that there can be any number of contact surfaces  134  and the contact surfaces  134  can be disposed in any suitable position. 
     The base portion  28  can further include a central pushup portion  140 , which is most clearly illustrated in  FIGS. 4 and 5 . The central pushup portion  140  can be centrally located (i.e., substantially centered on the longitudinal axis  150 ). The central pushup portion  140  can extend generally toward the finish  20 . In some embodiments, the central pushup portion  140 , when viewed in cross section ( FIG. 5 ), is generally in the shape of a truncated cone having a top surface  146  that is generally parallel to the support surfaces  134 . The pushup portion  140  can also include side surfaces  148  that slope upward toward the central longitudinal axis  150  of the container  10 . The side surfaces  148  can be frusto-conic or can include a plurality of planar surfaces that are arranged in series about the axis  150 . 
     Other shapes of the central pushup portion  140  are within the scope of the present disclosure. For instance, as shown in  FIG. 13 , the pushup portion  140  can be partially frusto-conic and partially cylindrical. Also, as shown in  FIGS. 17, 23, and 25 , the pushup portion  140  can be generally frusto-conic with a plurality of ribs  171  that extend at an angle along the side surface  148  at equal spacing about the axis  150 . Moreover, as shown in  FIGS. 19 and 21 , the pushup portion  140  can be annular, so that a depending frusto-conic projects exteriorly along the axis  150 .  FIGS. 35A-35D  show additional shapes for the pushup portion  140  (in respective bottom views of the container  10 ). For instance, the top surface  146  can be defined by a plurality of convexly curved lines that are arranged in series about the axis ( FIG. 35A ), an octagon or other polygon ( FIG. 35B ), alternating convexly and concavely curved lines ( FIG. 35C ), and a plurality of concavely curved lines ( FIG. 35D ). The side surface(s)  148  can project therefrom to have a corresponding shape. 
     As shown in  FIG. 34 , the top surface  146  and/or the side surface(s)  148  can have a concave and/or convex contour. For instance, the top surface  146  can have a concave curvature (indicated at  146 ′) or a convex curvature (indicated at  146 ″). Additionally, the side surface  148  can have a concave curvature (indicated at  148 ′), a convex curvature (indicated at  148 ″), or a S-shaped combination concave and convex curvature (indicated at  148 ′″). This curvature can be present when the container  10  is empty. Also, the curvature can be the result of deformation due to vacuum loads inside the container  10 . 
     The side surface  148  can also be stepped in some embodiments. Also, the side surface  148  can include ribs, convex or concave dimples, or rings. 
     The exact shape of the central pushup  140  can vary greatly depending on various design criteria. For additional details about suitable shapes of central pushup  140 , attention should be directed to commonly-assigned U.S. patent application Ser. No. 12/847,050, which published as U.S. Patent Publication No. 2011/0017700, which was filed on Jul. 30, 2010, and which is incorporated herein by reference in its entirety. 
     The central pushup  140  is generally where the preform gate is captured in the mold when the container  10  is blow molded. Located within the top surface  146  is the sub-portion of the base portion  28 , which typically includes polymer material that is not substantially molecularly oriented. 
     The container  10  can be hot-filled and, upon cooling, a vacuum in the container  10  can cause the central pushup  140  to move (e.g., along the axis  150 , etc.) to thereby decrease the internal volume of the container  10 . The central pushup  140  can also resiliently bend, flex, deform, or otherwise move in response to these vacuum forces. For instance, the top surface  146  can be flat or can convexly curve without the vacuum forces, but the vacuum forces can draw the top surface  146  upward to have a concave curvature as shown in  FIG. 34 . Likewise, the side surfaces  148  can deform due to the vacuum to be concave and/or convex as shown in  FIG. 34 . Thus, the central pushup  140  can be an important component of vacuum performance of the container  10  (i.e., the ability of the container  10  to absorb these vacuum forces without losing its ability to contain the commodity, withstand top loading, etc.) 
     Various factors have been found for the base portion  28  that can enhance such vacuum performance. In conventional applications, it has been found that material can be trapped or otherwise urged into the pushup portion of the base. The amount of material in these conventional applications is often more than is required for loading and/or vacuum response and, thus, represents unused material that adds to container weight and cost. This can be overcome by tailoring the pushup diameter (or width in terms of non-conical applications) and/or height to achieve improved loading and/or vacuum response from thinner materials. That is, by maximizing the performance of the central pushup  140 , the remaining container portions need not be designed to withstand a greater portion of the loading and vacuum forces, thereby enabling the overall container to be made lighter at a reduced cost. When all portions of the container are made to perform more efficiently, the container can be more finely designed and manufactured. 
     To this end, it has been found that by reducing the diameter of central pushup  140  and increasing the pushup height thereof, the material can be stretched more for improved performance. With reference to  FIG. 5 , each container  10  having pushup  140  defines several dimensions, including a pushup width Wp (which is generally a diameter of the entrance of central pushup  140 ), a pushup height Hp (which is generally a height from the contact surface  134  to the top surface  146 ), and an overall base width Wb (which is generally a diameter or width of base portion  28  of container  10 ). Based on performance testing, it has been found that relationships exist between these dimensions that lead to enhanced performance. Specifically, it has been found that a ratio of pushup height Hp to pushup width Wp of about 1:1.3 to about 1:1.4 is desirable (although ratios of about 1:1.0 to about 1:1.6 and ratios of about 1:1.0 to about 1:1.7 can be used). Moreover, a ratio of pushup width Wp to overall base width Wb of about 1:2.9 to about 1:3.1 is desirable (although ratios of about 1:2.9 to about 1:3.1 and ratios of about 1:1.0 to about 1:4.0 can be used). Moreover, in some embodiments, central pushup  140  can define a major diameter (e.g. typically equal approximately to the pushup width Wp or the diameter at the lowermost portion of central pushup  140 ). The central pushup  40  can further define a minor diameter (e.g. typically equal to the diameter of the top surface  146  or the width at the uppermost portion of central pushup  140 ). The combination of this major diameter and minor diameter can result in the formation of a truncated conical shape. Moreover, in some embodiments, the surface of this truncated conical shape can define a draft angle of less than about 45 degrees relative to central longitudinal axis  150 . It has been found that this major diameter or width can be less than about 50 mm and the minor diameter or width can be greater than about 5 mm, separately or in combination. 
     In some embodiments shown in  FIGS. 8 and 9 , the container  10  can include an inversion ring  142 . The inversion ring  142  can have a radius that is larger than the central pushup  140 , and the inversion ring  142  can completely surround and circumscribe the central pushup  140 . In the position shown in  FIGS. 8 and 9  and under certain internal vacuum forces, the inversion ring  142  can be drawn upward along the axis  150  away from the plane defined by the contact surface  134 . However, when the container  10  is formed, the inversion ring  142  can protrude outwardly away from the plane defined by the contact surface  134 . The transition between the central pushup  140  and the adjacent inversion ring  142  can be rapid in order to promote as much orientation as near the central pushup  140  as possible. This serves primarily to ensure a minimal wall thickness for the inversion ring  142 , in particular at the contact surface  134  of the base portion  28 . At a point along its circumferential shape, the inversion ring  142  may alternatively feature a small indentation, not illustrated but well known in the art, suitable for receiving a pawl that facilitates container rotation about the central longitudinal axis  150  during a labeling operation. 
     In some embodiments, as illustrated throughout the figures and notably in  FIGS. 28A-31A , the container  10  can further comprise one or more straps  170  formed along and/or within base portion  28 . As can be seen throughout  FIGS. 1-25 , straps  170  can be formed as recessed portions that are visible from the side of container  10 . That is, straps  170  can be formed such that they define a surface (i.e., a strap surface  173  that defines a strap axis of the respective strap  170 ). The strap surface  173  can be offset at a strap distance Ds ( FIG. 2 ) from contact surface(s)  134  in the Z-axis (generally along central longitudinal axis  150  of container  10 ). In some embodiments, this offset Ds between straps  170  and contact surface  134  can be in the range of about 5 mm to about 25 mm. Also, the strap surface  173  can extend transverse to the axis  150  to terminate adjacent the sidewall portion  24 . The periphery of the straps  170  can contour so as to transition into the sidewall portion  24  and/or the contact surfaces  134 . 
     At least a portion of the strap surface  173  can extend substantially parallel to the plane of the contact surfaces  134  as shown in  FIGS. 1-4 . Also, in some embodiments illustrated in  FIGS. 10-12 , at least a portion o the strap surface  173  can be partially inclined at a positive angle relative to the contact surface  134 . The angle can be less than 15 degrees in some embodiments. The angle can be greater than 15 degrees in other embodiments. 
       FIG. 36  shows various shapes that the straps  170  can have. For instance, the straps can concavely contour in the transverse direction (indicated at  170 ′), can convexly contour in the transverse direction (indicated at  170 ″), or can have one or more steps in the transverse direction (indicated at  170 ′″). 
       FIGS. 37-39  show how the straps can be shaped in plan view. For instance, the strap can have a sinusoidal shape (indicated at  170 ″″ in  FIG. 37 ) or the strap can include steps that expand or contract the strap in the transverse direction moving away from the axis  150  (indicated at  170 ′″″ in  FIG. 37 ). Moreover, the strap can taper inward or outward in the transverse direction (indicated at  170 ″″″ in  FIG. 39 ). Additionally, the straps can be arranged in a pinwheel shape (indicated at  170 ′″″″ in  FIG. 38 ). 
     The shape, dimensions, and other features of the straps  170  can depend upon container shape, styling, and performance criteria. Moreover, it should be recognized that the offset (along the axis  15 ) of one strap  170  can differ from the offset of another strap  170  on a single container to provide a tuned or otherwise varied load response profile. Straps  170  can interrupt contact surface  134 , thereby resulting in a plurality of contact surfaces  134  (also known as a footed or segmented standing surface). Because of the offset nature of straps  170  and their associate shape, size, and inclination (as will be discussed), straps  170  is visible from a side view orientation and formable via simplified mold systems (as will be discussed). 
     It has been found that the use of straps  170  can serve to reduce the overall material weight needed within base portion  28 , compared to conventional container designs, while simultaneously providing sufficient and comparable vacuum performance. In other words, straps  170  have permitted containers according to the principles of the present teachings to achieve and/or exceed performance criteria of conventional containers while also minimizing container weight and associated costs. 
     In some embodiments, container  10  can include at least one strap  170  disposed in base portion  28 . However, in alternative designs, additional straps  170  can be used, such as two, three, four, five, or more. Multiple straps  170  can radiate from the central pushup portion  140  and the longitudinal axis  150 . In some embodiments, the straps  170  can be equally spaced apart about the axis  150 . 
     Typically, although not limiting, rectangular containers ( FIGS. 1-28B ) may employ two or more even-numbered straps  170 . The straps  170  can, in some embodiments, bisect the midpoint (i.e., the middle region) of the respective sidewall. Stated differently, the strap  170  can intersect the respective sidewall approximately midway between the adjacent sidewalls. If the sidewall portion  24  defines a different polygonal cross section (taken perpendicular to the axis  150 ), the straps  170  can similarly bisect the sidewalls. 
     Similarly, although not limiting, cylindrical containers ( FIGS. 29A-30B ) may employ three or more odd-numbered or even-numbered straps  170 . As such, straps  170  can be disposed in a radial orientation such that each of the plurality of straps  170  radiates from a central point of base portion  28  to an external edge of the container  10  (e.g. adjacent sidewall portion  24 ). It should be noted, however, that although straps  170  may radiate from a central point, that does not mean that each strap  170  actually starts at the central point, but rather means that if a central axis of each strap  170  was extended inwardly they would generally meet at a common center. The relationship of the number of straps used to radial strength of container  10  has shown an increasing radial strength with an increasing number of straps used (see  FIG. 23B ). 
     It should also be noted that strap  170  can be used in conjunction with the aforementioned central pushup  140 , which would thereby interrupt straps  170 . However, alternatively, it should be noted that benefits of the present teachings may be realized using straps  170  without central pushup  140 . 
     As illustrated in the several figures, straps  170  can define any one or a number of shapes and sizes having assorted dimensional characteristics and ranges. However, it has been found that particular strap designs can lead to improved vacuum absorption and container integrity. By way of non-limiting example, it has been found that straps  170  can define a strap plane or central axis  172  that is generally parallel to contact surface  134  and/or a surface upon which container  10  sits, thereby resulting in a low strap angle. In other embodiments, strap plane/axis  172  can be inclined relative to contact surface  134  and/or the surface upon which container  10  sits, thereby resulting in a high strap angle. In some embodiments, this inclined strap plane/axis  172  can be inclined such that a lowest-most portion of inclined strap plane/axis  172  is toward an inbound or central area of container  10  and a highest-most portion of inclined strap plane/axis  172  is toward an outbound or external area of container  10  (e.g. adjacent sidewall portion  24 ). Examples of such inclination can be seen in  FIGS. 26B and 27B . 
     Low strap angles (e.g.,  FIGS. 1-4 ) provide base flexibility resulting in base flex that displaces volume through upward deflection. This upward deflection will be enhanced under vertical load providing additional volume displacement, transitioning to positive pressure to maximize filled capped topload. This complementary “co-flex base” technology provides volume displacement &amp; filled capped topload performance thereby resulting in a “lightweight panel-less” container configuration for multi-serve applications. Conversely, a high strap angle (e.g.,  FIGS. 26B and 27B ) provides base rigidity resulting in a base that enhances vertical and horizontal load bearing properties. Rectangular container designs provide sufficient volume displacement. This complementary “rigid-base” technology provides enhanced handling properties on fill-lines and tray distribution offerings thereby resulting in a “lightweight tray capable” container configuration for multi-serve applications. 
     By way of non-limiting example, it has been found that an inclination angle α ( FIG. 19 ) of strap plane/axis  172  of about 0 degrees to about 30 degrees (i.e. strap angle) can provide improved performance. This strap angle α can be measured in a side cross-section take along strap plane or axis  172  relative to a horizontal reference plane or axis as shown in  FIG. 19 . However, it should be recognized that other strap angles may be used and/or the direction of inclination can be varied. The relationship of inclination angle α to volume displacement of container  10  has shown an increasing volume displacement with a decreasing inclination angle α (see  FIG. 33A ). 
     With particular reference to  FIGS. 26A-27B , it should be noted that strap  170  can further define or include a secondary contour or shape when viewed generally along strap plane or axis  172 . That is, when viewing from the side of the container  10 , the strap  170  can define a peaked shape or trapezoid shape adjacent the sidewall portion  24  having a raised central area and downwardly extending side surfaces (see  FIGS. 26B and 27B ) as opposed to defining a generally flat, single plane. The trapezoidally shaped portion can be planar also and disposed at a draft angle relative to a horizontal (imaginary) reference line. This draft angle can be between 0 degrees and 45 degrees. In some embodiments, this section of the strap  170  can have a triangular shape that further provides improved vacuum response and structural integrity while simultaneously permitting reduction in material weight and costs. By way of non-limiting example, it has been found that a peak  175  of the strap  170  ( FIGS. 19, 26B and 27B ) can define a peak angle β ( FIG. 19 ) relative to a vertical or perpendicular reference line in the range of about 0 degrees to 90 degrees (flat strap  170 ). In some embodiments, peak angle β can define a range of about 1 degree to about 45 degrees. However, it should be recognized that other angles may be used and/or the direction and overall shape of strap  170  can be varied. The relationship of peak angle β to volume displacement of container  10  has shown an increasing volume displacement with a decreasing peak angle β (see  FIG. 23C ). 
     In some embodiments, as illustrated in  FIGS. 1, 29B, and 30B , base portion  28  can further comprise one or more ribs  180  formed in (e.g., entirely within) or along strap  170 . Ribs  180  can include an inwardly-directed channel (recessed toward the interior of the container  10 ) or outwardly-directed channel (projecting outward from the interior of the container  10 ). Also, the rib  180  can be contained entirely within the respective strap  170  or can extend out of the respective strap  170  in some embodiments. The ribs  180  can serve to tune or otherwise modify the vacuum response characteristics of straps  170 . In this way, ribs  180  serve to modify the response profile of one or more straps  170 . With reference to the several figures, ribs  180  can follow one of a number of pathways, such as a generally V-shaped pathway ( FIGS. 29B, 30B ). In some embodiments, these pathways can define a pair of arcuate channels  182  terminating at a central radius  184 . 
     The plastic container  10  of the present disclosure is a blow molded, biaxially oriented container with a unitary construction from a single or multi-layer material. A well-known stretch-molding, heat-setting process for making the one-piece plastic container  10  generally involves the manufacture of a preform (not shown) of a polyester material, such as polyethylene terephthalate (PET), having a shape well known to those skilled in the art similar to a test-tube with a generally cylindrical cross section. An exemplary method of manufacturing the plastic container  10  will be described in greater detail later. 
     Referring to  FIG. 32 , exemplary embodiments of a mold system  306  for blow molding the container  10  is illustrated. The mold system  306  can be employed for the manufacture of container geometries, namely base geometries, that could not be previously made. As illustrated in  FIG. 32 , in some embodiments, the mold system  306  can comprise a base system  310  disposed in operably connection with a sidewall system  320 . Base system  310  can be configured for forming generally an entire portion of base portion  28  of container  10  and extends radially and upward until a transition to sidewall portion  24 . Base system  310 , in some embodiments, can maintain a temperature that is different from sidewall system  320 —either hotter or colder than sidewall system  320 . This can facilitate formation of container  10  to speed up or slow down the relative formation of the base portion  28  of container  10  during molding. 
     In some embodiments, base system  310  can comprise a lower pressure cylinder to extend and retract a push up member  323  (shown in phantom in  FIG. 32 ). The push up member  323  can be used to extend or otherwise stretch central pushup  140  axially toward the interior of the container  10 . As seen in  FIG. 32 , push up member  323  can be centrally disposed in base system  310 . Also, the push up member  323  can have a retracted position, wherein the push up member  323  is close to flush with surrounding portions of the base system  310 , and an extended position (shown in phantom), wherein the push up member  323  can extend away from surrounding portions of the base system  310 . In the extended position, the push up member  323  can engage the preform during forming and urge preform upward (e.g. inwardly) to form central pushup  140 . Also, following formation of central pushup  140 , push up member  323  can be retracted to permit demolding of the final container  10  from the mold. In some additional embodiments, push up member  323  of base system  310  can be paired with a counter stretch rod, if desired. 
     An exemplary blow molding method of forming the container  10  will now be described. A preform version of container  10  includes a support ring, which may be used to carry or orient the preform through and at various stages of manufacture. For example, the preform may be carried by the support ring, the support ring may be used to aid in positioning the preform in a mold cavity  321  ( FIG. 32 ), or the support ring may be used to carry an intermediate container once molded. At the outset, the preform may be placed into the mold cavity  321  such that the support ring is captured at an upper end of the mold cavity  320 . In general, the mold cavity has an interior surface corresponding to a desired outer profile of the blown container. More specifically, the mold cavity according to the present teachings defines a body forming region, an optional moil forming region and an optional opening forming region. Once the resultant structure (hereinafter referred to as an intermediate container) has been formed, any moil created by the moil forming region may be severed and discarded. It should be appreciated that the use of a moil forming region and/or opening forming region are not necessarily in all forming methods. 
     In one example, 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 the mold cavity. The mold cavity may be 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 intermediate container thereby molecularly orienting the polyester material in an axial direction generally corresponding with the central longitudinal axis of the container  10 . While the stretch rod extends the preform, air having 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 in 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 intermediate container. The pressurized air holds the mostly biaxial molecularly oriented polyester material against the mold cavity for a period of approximately two (2) to five (5) seconds before removal of the intermediate container from the mold cavity. This process is known as heat setting and results in a heat-resistant container suitable for filling with a product at high temperatures. 
     Alternatively, other manufacturing methods, such as for example, extrusion blow molding, one step injection stretch blow molding and injection blow molding, using other conventional materials including, for example, high density polyethylene, polypropylene, polyethylene naphthalate (PEN), a PET/PEN blend or copolymer, and various multilayer structures may be suitable for the manufacture of plastic container  10 . Those having ordinary skill in the art will readily know and understand plastic container manufacturing method alternatives. 
     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 invention. 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 invention, and all such modifications are intended to be included within the scope of the invention.