CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent application Ser. No. 18/159,339, filed on Jan. 25, 2023, which is a continuation of U.S. patent application Ser. No. 16/594,524, filed on Oct. 7, 2019, now U.S. Pat. No. 11,565,867, issued Jan. 31, 2023, which is a continuation of U.S. patent application Ser. No. 15/074,791, filed on Mar. 18, 2016, now U.S. Pat. No. 10,435,223, issued Oct. 8, 2019, which is a continuation of U.S. patent application Ser. No. 13/415,831, filed on Mar. 8, 2012 (the '831 application, and published as US2013/0312368), now U.S. Pat. No. 9,731,884, issued Aug. 15, 2017.

The '831 application is a continuation-in-part of U.S. patent application Ser. No. 11/704,368, filed on Feb. 9, 2007, (the '368 application published as US 2008/0047964), now U.S. Pat. No. 8,584,879, issued Nov. 19, 2013.

The '831 application is also a continuation-in-part of U.S. patent application Ser. No. 11/704,318, filed Feb. 9, 2007 (the '318 application published as US2007/0199916), now abandoned.

The '831 application is also a continuation-in-part of U.S. patent application Ser. No. 13/412,572, filed on Mar. 5, 2012, now U.S. Pat. No. 9,145,223, issued Sep. 29, 2015, which is a continuation of U.S. patent application Ser. No. 11/704,338, filed Feb. 9, 2007, (the '338 application published as US 2007/0199915), now U.S. Pat. No. 8,127,955, issued Mar. 6, 2012.

The '831 application is also a continuation-in-part of U.S. patent application Ser. No. 13/284,907, filed Oct. 30, 2011, now abandoned.

The contents and disclosures of each of the aforementioned applications, their publications and patents are incorporated herein by reference thereto.

In addition to the priority applications listed above, the following patents and patent applications also contain related disclosure and are fully incorporated herein by reference: U.S. patent application Ser. No. 10/529,198, filed on Mar. 24, 2005, with a § 371 filing date of Dec. 15, 2005, now U.S. Pat. No. 8,152,010, issued Apr. 10, 2012; International Application No. PCT/NZ2003/000220, filed on Sep. 30, 2003; New Zealand Application Serial No. 521694, filed on Sep. 30, 2002; U.S. patent application Ser. No. 10/851,083, filed on May 24, 2004, now U.S. Pat. No. 7,543,713, issued Jun. 9, 2009; U.S. patent application Ser. No. 10/444,616, filed on May 23, 2003; U.S. patent application Ser. No. 10/124,734, filed on Apr. 17, 2002, now U.S. Pat. No. 6,612,451, issued Sep. 2, 2003; U.S. Provisional Patent Application No. 60/284,795, filed on Apr. 19, 2001; U.S. patent application Ser. No. 10/363,400, entitled “Semi-Rigid Collapsible Container”, filed Feb. 26, 2003, now U.S. Pat. No. 7,077,279, issued Jul. 18, 2006; International Application No. PCT/NZ01/00176, filed Aug. 29, 2001; New Zealand Application No. 506684, filed on Aug. 31, 2000 and entitled, “Semi-Rigid Collapsible Container”; New Zealand Application No. 512423, filed on Jun. 15, 2001 and entitled, “Semi-Rigid Collapsible Container”; International Application No. PCT/US2004/024581, filed on Jul. 30, 2004; U.S. Provisional Patent Application No. 60/551,771, filed on Mar. 11, 2004; and U.S. Provisional Application No. 60/491,179, filed on Jul. 30, 2003.

BACKGROUND OF THE INVENTION
1. Field of the Invention

The present invention relates generally to a hot-fill container structure that allows for the removal of vacuum pressure within the container, and more particularly, to a hot-fill container structure having an invertible vacuum panel deeply set into the base of the container. The present invention also relates to methods of making and processing containers having an invertible vacuum panel deeply set into the base of the container.

2. Related Art

So called “hot-fill” containers are known in the art. Plastic containers, such as PET containers, are filled with various liquid contents at an elevated temperature, typically around 185 degrees F. Once the liquid within the container cools, the volume of the contained liquid reduces, creating a vacuum within the container that pulls inwardly on the side and end walls of the container. This in turn leads to deformation of the plastic container if it is not constructed rigidly enough to resist the vacuum forces.

Typically, vacuum pressures have been accommodated by the use of vacuum panels that deflect inwardly under vacuum pressure. Known vacuum panels are typically located in the container sidewall and extend parallel to the longitudinal axis of the container, and flex inwardly under vacuum pressure toward the longitudinal axis.

It is also known in the prior art to have a flexible base region to provide additional vacuum compensation. All such known prior art containers, however, have substantially flat or inwardly recessed base surfaces that deflect further inward to compensate for the vacuum forces. Known flexible base regions have not been able to adequately compensate for the vacuum forces on their own (i.e., vacuum panels in the sidewall and/or or other reinforcing structures are still required).

Therefore, there remains a need in the art for plastic containers that overcome the aforementioned shortcomings of the prior art.

BRIEF SUMMARY OF THE INVENTIONS

The present invention relates to a polymeric or plastic container having an invertible pressure panel located in the container base. The pressure panel is movable from an initial, outwardly-inclined position, to an inverted, inwardly-inclined position, in order to reduce the volume of the container and accommodate for vacuum forces within the container. The entire pressure panel is set deeply into the base of the container, such that no portion of the pressure panel extends beyond the standing ring, regardless of whether the pressure panel is in the initial position or the inverted position. This configuration can allow the container to be supported by the standing ring regardless of whether the pressure panel is in the initial position or the inverted position.

Other plastic containers suitable for containing a liquid are disclosed in U.S. Pat. No. 5,261,544 issued to Weaver, Jr.; and U.S. Pat. No. 5,908,128 issued to Krishnakumar et al.

As disclosed in Weaver, Col. 5, lines 26-29, a polymeric container should be blow-molded with a minimum thickness of at least about 10 mils.

As disclosed in Krishnakumar, Col. 4, lines 17-24, a container of approximately 20 ounces in volume made from ‘bottle grade’ PET (having about 1.5% comonomer and an intrinsic viscosity of about 0.80) may have a side-wall thickness on the order of 0.4 mm, or 15.7 mils, in order to withstand containing a heated liquid.

According to one exemplary embodiment, the present invention relates to a plastic container comprising an upper portion including a finish defining an opening into the container, a lower portion including a base defining a standing surface, a sidewall extending between the upper portion and the lower portion, the sidewall defining a longitudinal axis, and at least one substantially transversely-oriented pressure panel located in the lower portion. The pressure panel can be movable between an outwardly-inclined position and an inwardly-inclined position to compensate for a change of pressure inside the container. The standing surface can define a standing plane, and the entire pressure panel can be located between the standing plane and the upper portion of the container when the pressure panel is in the outwardly-inclined position.

According to another exemplary embodiment, the present invention relates to a method of processing a plastic container, comprising the steps of (a) providing a plastic container having an upper portion including a finish, a sidewall, a lower portion including a base defining a standing surface, and a substantially transversely-oriented pressure panel located in the base; (b) introducing heated liquid contents into the plastic container with the pressure panel located in an outwardly-inclined position entirely between the standing surface and the upper portion; (c) capping the plastic container; and (d) moving the pressure panel to an inwardly-inclined position entirely between 30 the standing surface and the upper portion.

According to yet another exemplary embodiment, the present invention relates to a method of blow molding a plastic container, comprising the steps of (a) enclosing a softened polymer material within a blow mold defining a mold cavity, the blow mold comprising at least first and second side mold portions and a base mold portion; (b) inflating the polymer material within the blow mold to at least partially conform the polymer material to the blow mold cavity; and (c) displacing the base mold portion with respect to the first and second side mold portions to form a transverse pressure panel deeply set within a base portion of the plastic container.

Further objectives and advantages, as well as the structure and function of preferred embodiments will become apparent from a consideration of the description, drawings, and examples.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other features and advantages of the invention will be apparent from the following, more particular description of a preferred embodiment of the invention, as illustrated in the accompanying drawings wherein like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements.

FIG. 1 is a perspective view of an exemplary embodiment of a plastic container according to the present invention, shown with a pressure panel in an initial, outwardly-inclined position;

FIG. 2 is a side, sectional view of the plastic container of FIG. 1, shown with the pressure panel in the initial, outwardly-inclined position;

FIG. 3 is a side, sectional view of the plastic container of FIG. 1, shown with the pressure panel in an inverted, inwardly-inclined position;

FIG. 4 is a bottom view of the plastic container of FIG. 1;

FIG. 5 is a perspective view of another exemplary embodiment of a plastic container according to the present invention, shown with the pressure panel in the initial, outwardly-inclined position;

FIG. 6 is a bottom view of the plastic container of FIG. 5;

FIG. 7 is a perspective view of a portion of a plastic container according to yet another exemplary embodiment of the present invention, shown with the pressure panel in an initial, outwardly-inclined position;

FIG. 8 is a bottom view of the plastic container of FIG. 7;

FIG. 9 is a side, sectional view of a portion of the plastic container of FIG. 7, shown with the pressure panel in the initial, outwardly-inclined position;

FIG. 10 is a side, sectional view of a portion of the plastic container of FIG. 7, shown with the pressure panel in the inverted, inwardly-inclined position;

FIGS. 11A-11E schematically illustrate an exemplary method of processing a plastic container according to the present invention;

FIGS. 12A-12C schematically illustrate an exemplary method of forming a plastic container according to the present invention;

FIG. 13 is a side view of a portion of a plastic container according to another embodiment of the present invention;

FIG. 14 is a side, sectional view of the plastic container of FIG. 13, shown with the pressure panel in the initial, outwardly-inclined position;

FIG. 15 is a perspective view of the plastic container of FIG. 13, shown with the pressure panel in the initial, outwardly-inclined position;

FIG. 16 is a side, sectional view of a portion of a plastic container according to another embodiment of the present invention;

FIG. 17 is a perspective view of the plastic container of FIG. 16, shown with the pressure panel in the initial, outwardly-inclined position;

FIG. 18 is a side, sectional view of a portion of a plastic container according to another embodiment of the present invention;

FIG. 19 is a perspective view of the plastic container of FIG. 18, shown with the pressure panel in the initial, outwardly-inclined position;

FIG. 20 is a schematic representation of a system for handling plastic containers;

FIG. 21 is a schematic representation of handling plastic containers;

FIG. 22 illustrates a lower portion of a container similar to that shown in FIG. 7 according to an alternate embodiment;

FIG. 23 illustrates a lower portion of the container of FIG. 13 similar to the view shown in FIG. 8 according to an alternate embodiment;

FIG. 24 is a bottom plan view of FIG. 8 with planes C-C and D-D indicated;

FIG. 25 is a side section view of FIG. 15 taken along C-C;

FIG. 26 is a side section view of FIG. 15 taken along D-D;

FIG. 27A is a side view of the plastic container of FIG. 5;

FIGS. 27B and 27E are side sectional views of the plastic container of FIG. 6 through plane B-B;

FIGS. 27C and 27D are side sectional views of the plastic container of FIG. 6 through plane C-C;

FIG. 28 schematically depicts containers being filled and capped according to one embodiment of the invention;

FIG. 29 is a schematic plan view of an exemplary handling system that combines single containers with a container holding device according to an embodiment of the invention;

FIG. 30 is a front side elevation view of the handling system of FIG. 29;

FIG. 31 is an unfolded elevation view of a section of the combining portion of the handling system of FIG. 30 illustrating the movement of the actuators;

FIG. 32 is a schematic plan view of an activation portion of the handling system according to an alternate embodiment of the invention;

FIG. 33 is a detailed plan view of the activation portion of the handling system of FIG. 32;

FIG. 34 is an unfolded elevation view of a section of the activation portion of FIG. 32 illustrating the activation of the container and the removal of the container from the container holding device;

FIG. 35 is an enlarged view of a section of the activation portion of FIG. 34;

FIG. 36 is an enlarged view of the container holder removal section of FIG. 34; and,

FIG. 37 is the container of FIG. 2 with an overlay grid and measures.

FIG. 38 is a schematic representation of handling plastic containers.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the invention are discussed in detail below. In describing embodiments, specific terminology is employed for the sake of clarity. However, the invention is not intended to be limited to the specific terminology so selected. While specific exemplary embodiments are discussed, it should be understood that this is done for illustration purposes only. A person skilled in the relevant art will recognize that other components and configurations can be used without departing from the spirit and scope of the invention. All references cited herein are incorporated by reference as if each had been individually incorporated.

As discussed above, to accommodate vacuum forces during cooling of the liquid contents within a hot-fill container, plastic containers have typically included a series of vacuum panels located around the sidewall and/or in the base portion. The vacuum panels deform inwardly, and the base deforms upwardly, under the influence of the vacuum forces. This configuration attempts to prevent unwanted distortion elsewhere in the container. However, the container is still subjected to internal vacuum forces. The sidewalls and base merely provide a suitably resistant structure against that force. Additionally, the vacuum panels in the sidewall can undesirably detract from the appearance and feel of the container, and limit the design possibilities for the container.

Typically at a bottling plant, the containers are filled with a hot liquid and then capped before being subjected to a cold water spray, resulting in the formation of a vacuum within the container. The container structure needs to be able to cope with this vacuum force. U.S. patent application Ser. No. 10/529,198, filed on Dec. 15, 2005, the entire content of which is incorporated herein by reference, discloses hot-fill containers that provide for the substantial removal or substantial negation of the vacuum pressure within the containers. The disclosed containers include a transversely-oriented pressure panel located in the container base. The pressure panel is movable between an initial, outwardly inclined position, and an inverted, inwardly inclined position, in order to reduce the volume of the container and accommodate for vacuum forces within the container. The present invention relates to additional embodiments of this concept in which the pressure panel is set deeply into the base of the container, such that no portion of the pressure panel extends beyond the standing ring, regardless of whether the pressure panel is in the initial position or in the inverted position. This configuration can allow the container to be supported by the standing ring regardless of whether the pressure panel is in the initial position or the inverted position.

Referring to FIGS. 1-4, an exemplary embodiment of a plastic container 10 according to the present invention is shown. The container 10 can include an upper portion 12 including a finish 14 that defines an opening into the interior of the container 10. As shown, the finish 14 can include threads 16 or other structures adapted to secure a closure (not shown) onto the container 10. The container 10 can also include a lower portion 18 having a base 20, and a sidewall 22 extending between the upper portion 12 and the lower portion 18. The base 20 can define a standing surface 21 that is substantially flat and adapted to support the container 10 in a substantially upright position (e.g., with longitudinal axis A substantially perpendicular to the surface on which container 10 is resting).

In the exemplary embodiment shown, the sidewall 22 is substantially tubular and has a substantially circular transverse cross-sectional shape. Alternative cross-sectional shapes can include, for example, an oval transverse cross-section; a substantially square transverse cross-section; other substantially polygonal transverse cross-sectional shapes such as triangular, pentagonal, etc.; or combinations of curved and arced shapes with linear shapes. As will be understood by one of ordinary skill in the art, when the container 10 has a substantially polygonal transverse cross-sectional shape, the corners of the polygon are typically rounded or chamfered. Although the container 10 is shown as having reinforcing ribs or rings 23 in the sidewall 22 to resist paneling, dents and other unwanted deformation of the sidewall, particularly under vacuum force, other embodiments are possible where the sidewall 22 is substantially devoid of such features (e.g., the sidewall 22 can be smooth like that of a conventional glass container).

As best seen in FIG. 4, a portion of the base 20 can include a plurality of reinforcing ribs 24, however other embodiments with or without the reinforcing ribs 24 are possible.

The lower portion 18 of the container 10, and particularly the base 20, can include a substantially transversely-oriented pressure panel 26. The pressure panel 26 can be moved between an outwardly-inclined position (shown in FIGS. 1 and 2) and an inwardly-inclined position (shown in FIG. 3) in order to reduce the internal volume of the container 10 and compensate for any vacuum forces created within the container, for example, during the filling process. For example, the pressure panel 26 may substantially remove the internal vacuum that develops within the container 10 during a hot-fill process once the container 10 has been hot-filled, capped, and cooled.

As best seen in the sectional views of FIGS. 2 and 3, the pressure panel 26 can be deeply set into the container 10 in order to facilitate standing of the container 10 on its standing surface 21 regardless of whether the pressure panel 26 is located in the outwardly-inclined position (FIG. 2) or the inwardly-inclined position (FIG. 3). In other words, the entire pressure panel 26 structure can be located between the plane P of the standing surface 21 and the upper portion 12 of the container 10 when the pressure panel 26 is in the outwardly-inclined position (FIG. 2) and also when the pressure panel 26 is in the inwardly-inclined position (FIG. 3).

According to the exemplary embodiment shown in FIGS. 1-4, the lower portion 18 of the container 10 includes a concave outer wall portion 30 that extends from the lower end of the sidewall 22 to the standing surface 21. The standing surface may be a ring or annular portion as shown in FIG. 1, or may be discontinuous as shown in FIG. 5. The pressure panel 26 is deeply set into the lower portion 18 of the container 10 via an inner wall 32 that extends from the standing surface 21 to the pressure panel 26. The inner wall may therefore comprise an instep or hollow recessed portion between the pressure panel 26 and the standing surface 21. In the exemplary embodiment shown, the inner wall 32 is parallel or nearly parallel to the longitudinal axis A of the container 10, and provides the recessed portion with a concave annular ring shape; however, other configurations and/or inclinations of the inner wall 32 are possible that are not concave annular ring structures, and may have different angles as shown in FIGS. 18-19 with reference to the inner wall 1120. In addition, one of ordinary skill in the art will know that other configurations besides the inner wall 32 may be implemented to set the pressure panel 26 deeply into the lower portion 18. An annular, recessed channel 34 can be provided in the inner wall 32 adjacent the standing surface 21 to provide a further recessed concave ring structure in the inner wall 32. In the exemplary embodiment shown, the annular recessed channel has a substantially square or annular cross-section, however, other shapes are possible for the channel to be inwardly stepped. Channel 34 can act as a rib member and reinforce the foot portion or standing surface 21 and/or facilitate stacking of multiple containers on top of one another, depending on the shape and size of the finish 14 and/or closure.

In the exemplary embodiment of FIGS. 1-4, the standing surface 21, inner wall 32, and outer wall 30 are substantially continuous about the circumference of the container 10 (see FIG. 4). However, as shown in the alternative embodiment of FIGS. 5 and 6, and FIGS. 27A-27E, the container 10′ can have a standing surface 21, inner wall 32′, and outer wall 30′ that are discontinuous.

The pressure panel or inner annular wall 240 has an inner periphery 244 and an outer periphery 242, and is set, with respect to the longitudinal axis and the opening into the container, at an outward or downward angle prior to filling with a heated liquid. The outer annular wall includes support or foot portions 230 and the inner wall portions 32′ extend from the standing surfaces 21′ to the inner annular wall or pressure panel 240. Radial webs or straps 246 are uniformly spaced apart and separate each support 230. The web surface is closer to the finish than the footed contact surface, or expressed another way, the webs 246 are longitudinally displaced above the footed contact surface 21′. In addition, each support 230 has a larger arcuate extent than that of each radial web 246. The inner annular wall 240 extends within the concave outer annular wall 30′. The outer periphery 242 of the inner annular wall or pressure panel 240 merges with the inner wall 32′ of each of the supports 230, and radially or circumferentially with the plurality of spaced-apart, horizontally disposed, radial webs or straps 246 located adjacent the outer periphery 232 of the standing surface of the base. Each of the webs 246 extends between the supports 230 and connects to the container sidewall 22 in the lower portion 18 at an elevation above the horizontal plane “P” extending through the standing surface 21 to form radius 202 such that web surface 246 is visible from a side of the container. Preferably the inner annular wall 240 and the central dimple or push up 248 merge via an annular hinge 250 at the foot of the push-up, comprising radius 251.

In order to facilitate movement (e.g., folding) of the pressure panel 26 between the outwardly-inclined position of FIG. 2 and the inwardly-inclined position of FIG. 3, pressure panel 26 can include a decoupling or hinge structure 36 that is located between the inner wall 32 and the pressure panel 26. In the exemplary embodiment shown, the hinge structure 36 comprises a substantially flat, non-ribbed region, that is susceptible to folding, however, other configurations of the hinge structure, such as a crease, are possible.

Referring now particularly to FIG. 4, the pressure panel 26 can comprise an initiator portion 40 and a control portion 42. Both the initiator portion 40 and control portion 42 can comprise part of the pressure panel 26 that folds when the pressure panel 26 is moved from its initial position in FIG. 2 to its inverted position in FIG. 3. The initiator portion 40 can be adapted to move or fold before the rest of the pressure panel 26 (e.g., before the control portion 42). In the exemplary embodiment shown, the control portion 42 is at a steeper angle to the standing plane P than the initiator portion 40, thereby resisting expansion of the pressure panel from the inverted state (FIG. 3) to the initial state (FIG. 2), for example, if the container 10 were accidentally dropped.

In order to maximize the amount of vacuum compensation from the pressure panel 26, it is preferable for at least the control portion 42 to have a steep angle of inclination with respect to the standing plane P. As shown in FIG. 2, the control portion 42 can be at a first angle alpha, with respect to the standing plane P. According to one exemplary embodiment, the first angle alpha, can be at least 10 degrees, and preferably is between about 30 degrees and about 45 degrees. According to this embodiment, the initiator portion 1 can be at a second angle beta, with respect to standing plane P, that is at least 10 degrees less than the first angle alpha.

When the pressure panel is inverted from the outward state (FIG. 2) to the inward state (FIG. 3), it can undergo an angular change that is approximately equal to its angle of inclination. For example, if the control portion 42 is initially set at an angle alpha, of about 10 degrees, it will provide an angular change of approximately 20 degrees. At such a low angle of inclination, however, it can be difficult to provide an adequate amount of vacuum compensation in a hot-filled container. Therefore it is preferable to provide the initiator portion 40 and control portion 42 with steeper angles. For example, with the control portion set at an angle alpha, of about 35 degrees, the pressure panel 26 will undergo an angular change of about 70 degrees upon inversion. According to this exemplary embodiment, the initiator portion 40 can be set at an angle beta, of about 20 degrees.

Referring to FIGS. 22-23, a base portion of a container according to an alternative embodiment is shown, wherein the control portion of the pressure panel comprises a substantially continuous conical area extending around the base. According to this embodiment, the initiator portion 140 and the control portion 142 are set at a common angle, such that they form a substantially uniform pressure panel 126. However, initiator portion 140 may still be configured to provide the least amount of resistance to inversion of pressure panel 126, such that it still provides an initial area of folding or inversion. For example, the initiator portion 140 may have a smaller material thickness than the control portion 142. According to the embodiment shown in FIGS. 22-23, initiator portion 140 causes the pressure panel 126 to begin inversion at its region of widest diameter, near the hinge structure 136.

Additional structures may be added to the pressure panel 126 in order to add further control over the inversion process. For example, the pressure panel 126 may be divided into fluted regions, as shown in FIGS. 6 and 7. As shown, the fluted regions 145 can be outwardly convex, resulting in inward creases 127 between each outward flute and evenly distributed around the container's longitudinal axis to create alternating regions of greater and lesser angular inclination. Referring to FIGS. 24-26 in particular, panel portions 145 that are convex outwardly, and evenly distributed around the central axis create regions of greater angular set 219 and regions of lesser angular set 218. The angular set in the midline 218 of each of the plurality of flutes 145 has lesser angular set gamma than the angular set delta in the plurality of creases 219 created between each fluted panel portion 145. This may provide for greater control over the inversion of the panel. Such geometry provides increased resistance to reversion of the panel, and a more even distribution of forces when in the inverted position. This type of geometry can provide increased resistance against the panel returning from the inward position (FIG. 10) to the outward position (FIG. 9), for example, if the container were dropped. The fluted configuration can also provide more even distribution of forces on the pressure panel 126. According to an alternative embodiment, the flutes can be inwardly concave. Inwardly directed flutes offer less resistance to initial inverting forces, coupled with increased resistance to reverting back to the original, outward position. In this way, they behave in much the same manner as ribs to prevent the panel being forced back out of the outwardly inclined position, but allow for hinge movement from the first outwardly inclined position to the inwardly inclined position. Such inwardly or outwardly directed flutes or projections function as ribs to increase the force required to invert the panel. Further details regarding the pressure panel and fluting are disclosed in co-pending U.S. patent application Ser. No. 10/529,198, filed on Dec. 15, 2005, the entire content of which is incorporated herein by reference.

FIGS. 13 to 15 show another exemplary embodiment of a container that can be used as described herein. The container includes an upper portion 1102, shoulder 1104, body 1106 and base 1108. The upper portion 1102 includes an opening into the container which may be closed and sealed, such as via a screw cap using thread 1112.

The container body 1106 in the present example includes ribs 1114 in a first region thereof and panels 1116 in second portions thereof. Panels 1116 in this example act as vacuum panels as discussed below and also facilitate gripping of the container by a consumer, but in other examples may be configured to serve only as grip panels and not pressure panels. In another example, vacuum panels may be placed in the container body separately from the grips or without the grips.

The container base 1108 includes standing ring or bearing surface 1118 on which the container rests when in an upright position. Adjacent the standing ring 1118 is a recess or instep forming a first wall 1120 which joins pressure panel or second wall 1124 via a hinge structure 1122. An inwardly projecting push-up or section 1126 is provided in the center of the base 1108. The panel or second wall 1124 may include creases 1128 as shown which aid control over the configuration of the panel or second wall 1124 as it moves between outwardly and inwardly inclined positions.

The container of FIGS. 13 to 15 is particularly adapted to hot-fill applications but may be used in other applications where there are changes in pressure inside the container.

According to one hot-filling method using the container of FIGS. 13-15, the container is provided to a filling station with the second wall 1124 configured as shown in FIGS. 14 and 15. The container is then filled with hot or heated liquid and sealed, for example, using a screw cap. As the container cools, contents of the container (particularly the headspace), contract. This causes the pressure in the container to drop. Cooling may be accelerated, for example, by spraying the outside of the container with water.

To prevent unwanted deformation of the container caused by the reduction in internal pressure, one or both pressure panels 1116, 1124 are configured to move inwards to reduce the container volume and increase the internal pressure of the container. In one example, at least the panels 1116 provided in the container sidewall are adapted to move inwards through action of the vacuum force generated inside the container during cooling, and in another example the panel 1124 is adapted to move inward through action of the vacuum force generated inside the container during cooling. In a third example, both move inward, and in a further example, the container sidewalls are subjected to vacuum force prior to the base.

In the present example, panel 1124 is also configured to move to adjust the container volume. More particularly, panel 1124 is configured to invert about hinge structure 1122 from being outwardly inclined as shown in FIGS. 14 and 15 to being inwardly inclined (not shown).

Inversion of the panel 1124 may be initiated by engagement of a pusher or other external mechanical force against the base 1108, preferably the centrally located push-up 1126 of the base 1108. Additionally or alternatively, the panel 1124 may include an initiator portion that is configured to initiate or cause the rest of the panel to move between the outwardly and inwardly inclined positions. The initiator portion may reduce or obviate the need for a pusher, providing for movement of the panel 1124 due to the forces generated by the pressure differential between the inside and outside of the container. To this end, the initiator portion may have a lower angle of inclination than other portions of the panel 1124 relative to the standing plane formed by the standing ring 1118.

According to preferred embodiments, opposing vacuum panels 1116 are subjected to vacuum force prior to repositioning of the base. More preferably, the vacuum panels 1116 move inwards prior to movement of the second wall 30 or panel 1124 to the inwardly inclined position. Other methods of using containers as described herein can also be used with the container of FIGS. 13-15.

It will be noted that the instep or first wall 1120 is configured so as to elevate the panel 1124 and other portions of the base 1108 above the standing ring 1118 when the panel 1124 is outwardly inclined. Such a configuration provides improved container stability during the filling operations. However, the instep or first wall 1120 may be recessed to a lesser extent such that a portion of the base extends below the standing ring 1118 when the panel 1124 is outwardly inclined. As will be appreciated, this will mean that different portions of the container base 1108 act as the standing ring depending on whether the panel or second wall 1124 is inwardly or outwardly inclined.

The container shown in FIGS. 13 to 15 may also be used in pasteurisation processes. According to an example such process, the container is filled with the panel 1116, 1124 in the inward position and then sealed. The container and its contents are then heated, causing an increase in internal pressure. As a result of this the panels 1116, 1124 move to an outward position. After the heating stage of the pasteurisation process is completed and the container is cooled, the panels 1116, 1124 preferably revert to the inwardly inclined position.

According to preferred embodiments, different stages of the filling and/or pasteurisation processes may be performed at different stations within a filling or processing facility. To this end, the container may be conveyed in between stages or during a particular stage depending on system requirements and preferences.

As stated above, the containers according to the present invention may be manufactured with the base panel extending above or below the standing ring, providing for various degrees of container stability during the filling operations.

The process of positioning the moveable portion of a base of the container into a first filling position or to a second position after filling a hot product into the container and after creating a vacuum by cooling, may be further controlled by stabilizing the container in a holding device, or the containers may also be stabilized by supporting the neck of the container (FIG. 28), as discussed below.

The processing of a container, can be accomplished as part of a conveyor system. In one such system, as seen in FIG. 29, containers C can be conveyed singularly to a combining system that combines container holding devices and containers. The combining system of FIG. 29 includes a container in-feed 518a and a container holding device in-feed 520. As will be more fully described below, this system may be one way to stabilize containers with projected bottom portions that are unable to be supported by their bottom surfaces alone. Container in-feed 518a includes a feed scroll assembly 524, which feeds and spaces the containers at the appropriate spacing for merging containers C into a feed-in wheel 522a. Wheel 522a comprises a generally star-shaped wheel, which feeds the containers to a main turret system 530 and includes a stationary or fixed plate 523a that supports the respective containers while containers C are fed to turret system 530, where the containers are matched up with a container holding device H and then deactivated to have a projecting bottom portion.

Similarly, container holding devices H are fed in and spaced by a second feed scroll 526, which feeds in and spaces container holding devices H to match the spacing on a second feed-in wheel 528, which also comprises a generally star-shaped wheel. Feed-in wheel 528 similarly includes a fixed plate 528a for supporting container holding devices H while they are fed into turret system 530. Container holding devices H are fed into main turret system 530 where containers C are placed in container holding devices H, with holding devices H providing a stable bottom surface for processing the containers. In the illustrated embodiment, main turret system 530 rotates in a clock-wise direction to align the respective containers over the container holding devices fed in by star wheel 528. However, it should be understood that the direction of rotation may be changed. Wheels 522a and 528 are driven by a motor 529 (FIG. 30), which is drivingly coupled, for example, by a belt or chain or the like, to gears or sheaves mounted on the respective shafts of wheels 522a and 528.

Container holding devices H comprise disc-shaped members with a first recess with an upwardly facing opening for receiving the lower end of a container and a second recess with downwardly facing opening, which extends upwardly from the downwardly facing side of the disc-shaped member through to the first recess to form a transverse passage through the disc-shaped member. The second recess is smaller in diameter than the first so as to form a shelf in the disc-shaped member on which at least the perimeter of the container can rest. As noted above, when a container is deactivated, its vacuum panels will be extended or projecting from the bottom surface. The extended or projecting portion is accommodated by the second recess. In addition, the containers can then be activated through the transverse passage formed by the second recess, as will be appreciated more fully in reference to FIGS. 34-35 described herein.

In order to provide extra volume and accommodation of pressure changes needed when the containers are filled with a hot product, such as a hot liquid or a partly solid product, the inverted projection of the blow-molded containers should be pushed back out of the container (deactivated). For example, a mechanical operation employing a rod that enters the neck of the blow-molded container and pushes against the inverted projection of the blow-molded container causing the inverted projection to move out and project from the bottom of the base, as shown in FIGS. 34-35. Alternatively, other methods of deploying the inverted projection disposed inside a blow-molded container, such as injecting pressurized air into the blow-molded container, may be used to force the inverted projection outside of the container. Thus, in this embodiment, the blow-molded projection is initially inverted inside the container and then, a repositioning operation pushes the inverted projection so that it projects out of the container.

Referring to FIG. 30, main turret system 530 includes a central shaft 530a, which supports a container carrier wheel 532, a plurality of radially spaced container actuator assemblies 534 and, further, a plurality of radially spaced container holder actuator assemblies 536 (FIG. 31). Actuator assemblies 534 deactivate the containers (extend the inverted projection outside the bottom surface of the container), while actuator assemblies 536 support the container holding devices and containers. Shaft 530a is also driven by motor 529, which is coupled to a gear or sheave mounted to shaft 530a by a belt or chain or the like. In addition, main turret system 530 includes a fixed plate 532a for supporting the containers as they are fed into container carrier wheel 532. However, fixed plate 532a terminates adjacent the feed-in point of the container holding devices so that the containers can be placed or dropped into the container holding devices under the force of gravity, for example. Container holding devices H are then supported on a rotating plate 532b, which rotates and conveys container holding devices H to discharge wheel 522b, which thereafter feeds the container holding devices and containers to a conveyor 518b, which conveys the container holding devices and containers to a filling system. Rotating plate 532b includes openings or is perforated so that the extendable rods of the actuator assemblies 536, which rotate with the rotating plate, may extend through the rotating plate to raise the container holding devices and containers and feed the container holding devices and containers to a fixed plate or platform 523b for feeding to discharge wheel 522b.

As best seen in FIG. 31, each actuator assembly 534, 536 is positioned to align with a respective container C and container holding device H. Each actuator assembly 534 includes an extendable rod 538 for deactivating containers C, as will be described below. Each actuator assembly 536 also includes an extendable rod 540 and a pusher member 542, which supports a container holding device, while a container C is dropped into the container holding device H and, further supports the container holding device H while the container is deactivated by extendable rod 538. To deactivate a container, actuator assembly 534 is actuated to extend its extendable rod 538 so that it extends into the container C and applies a downward force onto the invertible projection (512) of the container to thereby move the projection to an extended position to increase the volume of container C for the hot-filling and post-cooling process that follows. After rod 538 has fully extended the invertible projection of a container, rod 538 is retracted so that the container holding device and container may be conveyed for further processing.

Again as best seen in FIG. 31, while rod 538 is retracted, extendable rod 540 of actuator 536 is further extended to raise the container holding device and container to an elevation for placement on fixed plate or platform 523b of discharge wheel 522b. Wheel 522b feeds the container holding device and container to an adjacent conveyor 518b, which conveys the container holding device and container to filling portion 516 of the container processing system. Discharge wheel 522b is similar driven by motor 529, which is coupled to a gear or sheave mounted on its respective shaft.

Referring again to FIGS. 30 and 31, main turret assembly 530 includes an upper cam assembly 550 and a lower cam assembly 552. Cam assemblies 550 and 552 comprise annular cam plates that encircle shaft 530a and actuator assemblies 534 and 536. The cam plates provide cam surfaces to actuate the actuator assemblies, as will be more fully described below. Upper cam assembly 550 includes upper cam plate 554 and a lower cam plate 556, which define there between a cam surface or groove 558 for guiding the respective extendable rods 538 of actuator assemblies 534. Similarly, lower cam assembly 552 includes a lower cam plate 560 and an upper cam plate 562 which define there between a cam surface or groove 564 for guiding extendable rods 540 of actuator assemblies 536. Mounted to extendable rod 538 may be a guide member or cam follower, which engages cam groove or surface 558 of upper cam assembly 550. As noted previously, actuator assemblies 534 are mounted in a radial arrangement on main turret system 530 and, further, are rotatably mounted such that actuator assemblies 534 rotate with shaft 530a and container holder wheel 532. In addition, actuator assemblies 534 may rotate in a manner to be synchronized with the in-feed of containers C. As each of the respective actuator assemblies 534 is rotated about main turret system 530 with a respective container, the cam follower is guided by groove 558 of cam assembly 550, thereby raising and lowering extendable member 538 to deactivate the containers, as previously noted, after the containers are loaded into the container holding devices.

If the container holding devices are not used, the containers according to one embodiment of the invention may be supported at the neck of each container during the filling and capping operations to provide maximum control of the container processes. This may be achieved by rails R, which support the neck of the container, and a traditional cleat and chain drive, or any other known like-conveying modes for moving the containers along the rails R of the production line. The extendable projection 512 may be positioned outside the container C by an actuator as described above.

The process of repositioning the projection outside of the container preferably should occur right before the filling of the hot product into the container. According to one embodiment of the invention, the neck of a container would be sufficiently supported by rails so that the repositioning operation could force or pop the inverted base outside of the container without causing the container to fall off the rail conveyor system. In some instances, it may not be necessary to invert the projection prior to leaving the blow-molding operation and these containers are moved directly to a filling station. The container with an extended projection, still supported by its neck, may be moved by a traditional neck rail drive to the filling and capping operations, as schematically shown in FIG. 28.

Referring to FIGS. 32 and 33, one system for singularly activating containers C includes a feed-in scroll assembly 584, which feeds and, further, spaces the respective container holding devices and their containers at a spacing appropriate for feeding into a feed-in wheel 586. Feed-in wheel 586 is of similar construction to wheel 522b and includes a generally star-shaped wheel that feeds-in the container holders and containers to turret assembly 588. Turret assembly 588 is of similar construction to turret assembly 530 and includes a container holder wheel 590 for guiding and moving container holding devices H and containers C in a circular path and, further, a plurality of actuator assemblies 5104 and 5106 for removing the containers from the container holders and for activating the respective containers, as will be more fully described below. After the respective containers have been activated and the respective containers removed from the container holding devices, the holders are discharged by a discharge wheel 592 to conveyor 594 and the containers are discharged by a discharge wheel 596 to a conveyor 598 for further processing. Wheels 586, 592, and 596 may be driven by a common motor, which is drivingly coupled to gears or sheaves mounted to the respective shafts of wheels 586, 592, and 596.

As previously noted, turret assembly 588 is of similar construction to turret assembly 530 and includes container holder wheel 590, upper and lower cam assemblies 5100 and 5102, respectively, a plurality of actuator assemblies 5104 for griping the containers, and a plurality of actuator assemblies 5106 for activating the containers. In addition, turret system 588 includes a support plate 5107, which supports the container holders and containers as they are moved by turret system 588. As best seen in FIG. 33, container holder wheel 590, actuator assemblies 5104, actuator assemblies 5106, and plate 5107 are commonly mounted to shaft 588a so that they rotate in unison. Shaft 588a is similarly driven by the common motor, which is drivingly coupled to a gear or sheave mounted on shaft 588a.

Looking at FIGS. 34-36, actuator assemblies 5104 and 5106 are similarly controlled by upper and lower cam assemblies 5100 and 5102, to remove the containers C from the container holding devices H and activate the respective containers so that the containers generally assume their normal geometrically stable configuration wherein the containers can be supported from their bottom surfaces and be conveyed on a conventional conveyor. Referring to FIG. 34, each actuator assembly 5104 includes actuator assembly 534 and a container gripper 5108 that is mounted to the extendable rod 538 of actuator assembly 534. As would be understood, grippers 5108 are, therefore, extended or retracted with the extension or retraction of extendable rods 538, which is controlled by upper cam assembly 5100.

Similar to upper cam assembly 550, upper cam assembly 5100 includes an upper plate 5110 and a lower plate 5112, which define therebetween a cam surface or recess 5114, which guides guide members 572 of actuator assemblies 5104 to thereby extend and retract extendable rods 538 and in turn to extend and retract container grippers 5108. As the containers are conveyed through turret assembly 588, a respective gripper 5108 is lowered onto a respective container by its respective extendable rod 538. Once the gripper is positioned on the respective container, actuator assemblies 5106 are then actuated to extend their respective extendable rods 5116, which extend through plate 5107 and holders H, to apply a compressive force onto the invertible projections of the containers to move the projections to their recessed or retracted positions to thereby activate the containers. As would be understood, the upward force generated by extendable rod 5116 is counteracted by the downward force of a gripper 5108 on container C. After the activation of each container is complete, the container then can be removed from the holder by its respective gripper 5108.

Referring to FIGS. 34-35, each actuator assembly 5106 is of similar construction to actuator assemblies 534 and 536 and includes a housing 5120, which supports extendable rod 5116. Similar to the extendable rods of actuator assemblies 534 and 536, extendable rod 5116 includes mounted thereto a guide 5122, which engages the cam surface or recess 5124 of lower cam assembly 5102. In this manner, guide member 5122 extends and retracts extendable rod 5116 as it follows cam surface 5124 through turret assembly 588. As noted previously, when extendable rod 5116 is extended, it passes through the base of container holding device H to extend and contact the lower surface of container C and, further, to apply a force sufficient to compress or move the invertible projection its retracted position so that container C can again resume its geometrically stable configuration for normal handling or processing.

The physics of manipulating the activation panel P or extendable rod 5116 is a calculated science recognizing 1) Headspace in a container; 2) Product density in a hot-filled container; 3) Thermal differences from the fill temperature through the cooler temperature through the ambient storage temperature and finally the refrigerated temperature; and 4) Water vapor transmission. By recognizing all of these factors, the size and travel of the activation panel P or extendable rod 5116 is calculated so as to achieve predictable and repeatable results. With the vacuum removed from the hot-filled container, the container can be light-weighted because the need to add weight to resist a vacuum or to build vacuum panels is no longer necessary. Weight reduction of a container can be anticipated to be approximately 10%.

FIGS. 16 and 17 show a container according to another embodiment. Many of the features of this embodiment are the same or substantially the same as those of the embodiment of FIGS. 13 to 15 and like references have been used to aid clarity. Only features that differ from the embodiment of FIGS. 13 to 15 will be described.

As shown in FIGS. 16 and 17, the container of this embodiment includes first and second panels 1116 on two opposing faces of the sidewall thereof, at least one of which is a vacuum panel.

FIGS. 18 and 19 show another embodiment of a container that is substantially identical to the container of FIGS. 16 and 17 and again only points of difference will be described.

Notably, in the embodiment of FIGS. 18 and 19, the first wall or instep 1120 is inclined at a lesser angle than in the embodiment of FIGS. 16 and 17. As will be appreciated, other angles of inclination may also be used.

The operation or preferred use of the containers of FIGS. 16 and 17, and FIGS. 18 and 19, is substantially identical to that described in relation to the embodiment of FIGS. 13 to 15.

Referring to FIGS. 11A-11E, an exemplary method of processing a plastic container according to the present invention is shown. Prior to processing, the container 10 may be formed (e.g., blow molded) with the pressure panel 26 in the inwardly-inclined position. According to this embodiment, a force can be applied to the pressure panel 26 in order to move the pressure panel 26 into the outwardly-inclined position. For example, as shown in FIGS. 11A and 11B, a first mechanical pusher 50 can be introduced through the opening in the container finish 14 and forced downwardly on the pressure panel 26 in order to move it to the outwardly-inclined position (shown in FIG. 11C). One of ordinary skill in the art will know that other types of mechanical or other forces can alternatively be used to move the pressure panel 26 into the outwardly-inclined position. Alternatively, the container 10 can be initially formed with the pressure panel 26 located in the outwardly-inclined position.

Referring to FIG. 11C, the container 10 can be filled with liquid contents when the pressure panel 26 is located in the outwardly-inclined position. Particularly, the container 10 can be “hot-filled” with the liquid contents at an elevated temperature, for example, 185 degrees C. As shown in FIG. 11C, the liquid contents can be introduced into the container 10 via a filling nozzle 52 inserted through the opening in the container finish 10, although one of ordinary skill in the art will know that any number of known filling devices and techniques can be implemented. According to an alternative embodiment, the first mechanical pusher 50 and the filling nozzle 52 can be the same instrument.

Referring to FIG. 11D, once the container 10 has been filled to the desired level, the filling nozzle 52 can be removed, and a cap 54 can be applied to the container finish 14. Any number of capping techniques and devices known in the art can be used to apply the cap 54 to the container finish 14. Next the container 10 can be cooled, for example, by spraying the container 10 with cool water, or alternatively, by leaving the container 10 in ambient conditions for a sufficient amount of time. As the container 10 and its contents cool, the contents tend to contract. This volumetric change inside the sealed container 10 can create a vacuum force within the container 10.

In order to alleviate all or a portion of the vacuum forces within the container 10, the pressure panel 26 can be moved from the outwardly-inclined position of FIG. 11D to the inwardly-inclined position of FIG. 11E. For example, following filling, capping, and cooling of the container 10, an external force can be applied to the pressure panel 26, for example, by a second mechanical pusher 56, as shown in FIG. 11D. Alternatively, the pressure panel 26 can be moved by the creation of relative movement of the container 10 relative to a punch or similar apparatus, in order to force the pressure panel 26 into the inwardly-inclined position. Alternatively, the pressure panel 26 can invert to the inwardly-inclined position under the internal vacuum forces within the sealed container 10. For example, all or a portion of the pressure panel 26 (e.g., the initiator portion) can be made flexible enough to cause the pressure panel 26 to invert under the internal vacuum forces.

The inversion of the pressure panel 26 from the outwardly-inclined position to the inwardly-inclined position reduces the internal volume of the container 10, and thereby increases the pressure inside the sealed container 10. This can alleviate any vacuum created within the container 10 due to the hot-fill process. This can also remedy any deformation of the container 10 that was caused as a result of the internal vacuum.

As shown in FIGS. 11A-E, the entire pressure panel 26 is above the plane P of the standing surface 21 (see FIG. 11C) of the container 10. As a result of this configuration, the containers 10 according to the present invention can be stored, transported, and capped/filled, etc., all while standing on the standing surface 21. This can eliminate the need for any adapters or other devices to stabilize the container 10 in the upright position. This can also make the containers 10 of the present invention more readily adapted for use with conventional, existing container transports, capping and filling stations, and storage facilities.

Referring to FIGS. 12A-C, an exemplary method of blow molding a plastic container according to the present invention is shown. Referring to FIG. 12A, the method includes enclosing a softened polymer material (such as PET, PEN, PP, blends thereof, and other suitable materials known in the art) within a blow mold. In the exemplary embodiment shown, the polymer material comprises a plastic container preform 60. However, according to an alternative embodiment, the polymer material can comprise a tube of extruded polymer material, for example, as used in the known process of “extrusion blow molding.”

The blow mold can comprise two or more side mold portions 62, 64, and a base mold portion 66. The side mold portions 62, 64 can move from an open position (not shown) in which the side mold portions are separated from one another, to a closed position, shown in FIGS. 12A-C. In the closed position, shown, the side mold portions 62, 64 define a mold cavity 68 having an open bottom. The mold cavity 68 corresponds to the shape of a plastic container to be molded therein. The base mold portion 66 is located in the open bottom region of the mold cavity 68 and is movable with respect to the side mold portions 62, 64 in the vertical direction (as viewed in FIGS. 12A-C) between the retracted position shown in FIGS. 12A and 12B, and the extended position shown in FIG. 12C. Mechanical, pneumatic, hydraulic, or other means known in the art can be implemented to move the base mold portion 66 between the retracted and extended positions.

A stretch rod 70 can be inserted into the neck portion of the softened preform 60, and can be used to stretch or elongate the preform 60. Air or another medium can be expelled from the stretch rod 70 or other device to at least partially inflate the preform 60 into conformity with the mold cavity 68 in what is commonly known in the art of stretch blow molding as a “pre-blow” step. Preferably, the preform 60 is inflated into substantially complete conformity with the mold cavity 68 while the base mold portion 66 is in the retracted position, as shown in FIG. 12B. In order to stretch blow mold the container from the partially inflated volume, it is commonly known in the art of stretch blow molding to increase the pressure during the final blowing step in order to force the plastic material into complete conformity with the mold cavity 68. This can eliminate the need for the polymer material to expand deeply into tight corners, narrow spaces, etc., that are associated with the deeply-set pressure panel of the present invention. This can avoid resultant thin or weak spots in the formed container.

While the polymer material is still in a softened state, the base mold portion 66 can be displaced upwardly into the mold cavity 68 to form a transverse pressure panel deeply set within the base portion of the plastic container (see, for example, the base 20 and pressure panel 26 of FIGS. 1-4). Air can continue to be expelled to blowing pressure into the stretch rod in the blow mold cavity during displacement of the base mold portion 66 to the extended position, or alternatively, the supply of air can be turned off. Referring to FIGS. 1-4, by “deeply set” it is meant that the pressure panel 26 is located entirely between the standing plane P and the upper portion 12 of the container when the pressure panel 26 is in the outwardly-inclined position (FIG. 2) and when it is in the inwardly-inclined position (FIG. 3). In the exemplary embodiment of FIGS. 12A-C, the base mold portion 66 moves substantially along the longitudinal axis of the plastic container being formed in the mold cavity 68, however, other orientations are possible.

Once the plastic container has been formed in the mold cavity 68, the base mold portion 66 can return to the retracted position, and the side mold portions 62, 64 can separate to release the formed container.

By utilizing the blow molding method of the present invention, it is possible to initially form the general container shape with a generally flat bottom portion, and then deflect the bottom upwardly at orientation temperature. As a result, the container base and deeply-set pressure panel can be of improved material thickness and uniformity. In addition, the base and pressure panel can be multi-axially stretch oriented to provide increased strength without the attendant thinness or weakness at the heel portion of the bottle.

The base of the plastic container according to the present invention is preferably crystallized to some extent. Some degree of crystallinity and/or biaxial orientation can be achieved normally during the blow molding process. However, crystallization can be promoted through heat setting of the container. For example, the walls and base of the mold can be held at an elevated temperature to promote crystallization. When the container is heat set at a temperature of about 180 degrees F., the container sidewalls, base, pressure panel, etc., can be typically crystallized to about 20%. This degree of crystallinity is typical for a blow molding process and does not represent a significant amount of heat setting or increased crystallinity or orientation, as compared with a typically prepared container. However, the properties of the base and pressure panel of the present invention can be advantageously enhanced by heat setting the container, and particularly the base and pressure panel, at ever higher temperatures. Such temperatures can be, for example, greater than 250 degrees F. and can be 325 degrees F. or even higher. When these elevated heat set temperatures are utilized, crystallinity can be increased to greater than 20% or 25% or more. One drawback of increasing crystallinity and biaxial orientation in a plastic container is that this process introduces opacity into the normally clear material. However, unlike bases in prior art containers, which can require a crystallinity of 30% or more, utilizing crystallinities of as low as 22-25% with a base structure according to the present invention can achieve significant structural integrity, while maintaining the substantial clarity of a base that is preferred by manufacturers, packagers and consumers.

U.S. Pat. Nos. 4,465,199; 3,949,033; 4,378,328; and 5,004,109, all of which are incorporated herein by reference, disclose further details relating to blow molding methods utilizing displaceable mold portions. The methods disclosed in these references can also be implemented to form plastic containers according to the present invention. According to an alternative embodiment of the invention, the plastic container can be removed from the blow mold prior to forming the deeply-set pressure panel. Outside of the mold, the pressure-panel and related structure(s) can be formed in the base of the plastic container using a mandrel or similar device. U.S. Pat. No. 4,117,062, the entire content of which is incorporated herein by reference, provides further details on this type of post-mold processing.

The embodiments illustrated and discussed in this specification are intended only to teach those skilled in the art the best way known to the inventors to make and use the invention. Nothing in this specification should be considered as limiting the scope of the present invention. All examples presented are representative and non-limiting. The above-described embodiments of the invention may be modified or varied, without departing from the invention, as appreciated by those skilled in the art in light of the above teachings. It is therefore to be understood that, within the scope of the claims and their equivalents, the invention may be practiced otherwise than as specifically described.