U.S. patent application number 10/391758 was filed with the patent office on 2003-12-04 for container with stackable base.
This patent application is currently assigned to Graham Packaging Company, LP. Invention is credited to Trude, Gregory Allan.
Application Number | 20030221987 10/391758 |
Document ID | / |
Family ID | 28454672 |
Filed Date | 2003-12-04 |
United States Patent
Application |
20030221987 |
Kind Code |
A1 |
Trude, Gregory Allan |
December 4, 2003 |
Container with stackable base
Abstract
A stackable, heat processable, blow molded, plastic container is
disclosed. The container has a body that has top and bottom ends
and a tubular sidewall. The container also has a dome with a finish
having an opening. The dome is connected to the top end of the body
and the finish is adapted to engage a first closure. Finally, the
container has a base connected to the bottom end of the body. The
base is contoured to engage at least a portion of a protrusion on a
second closure, thus causing the two containers to be
stackable.
Inventors: |
Trude, Gregory Allan; (Seven
Valleys, PA) |
Correspondence
Address: |
VENABLE, BAETJER, HOWARD AND CIVILETTI, LLP
P.O. BOX 34385
WASHINGTON
DC
20043-9998
US
|
Assignee: |
Graham Packaging Company,
LP
York
PA
|
Family ID: |
28454672 |
Appl. No.: |
10/391758 |
Filed: |
March 20, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60365530 |
Mar 20, 2002 |
|
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|
Current U.S.
Class: |
206/508 |
Current CPC
Class: |
B65D 21/0231 20130101;
B65D 21/0222 20130101; B65D 79/0084 20200501; B65D 1/0276
20130101 |
Class at
Publication: |
206/508 |
International
Class: |
B65D 021/00; B65D
085/62 |
Claims
What is claimed is:
1. A stackable, heat processable, blow molded, plastic container
comprising: a body having top and bottom ends and a tubular
sidewall; a dome with a finish having an opening, the dome being
connected to the top end of the body, the finish adapted to engage
a first closure; and a base connected to the bottom end of the
body, the base being contoured to engage a portion of a protrusion
on a second closure.
2. The stackable, heat processable, blow molded, plastic container
of claim 1, wherein the protrusion defines a peripheral ring.
3. The stackable, heat processable, blow molded, plastic container
of claim 1, wherein the finish and the first closure threadedly
engage each other.
4. The stackable, heat processable, blow molded, plastic container
of claim 1, the second closure further comprising: an outer ring
portion; and an inner disc portion, wherein the protrusion is
formed on the outer ring portion.
5. The stackable, heat processable, blow molded, plastic container
of claim 1, the second closure further comprising: an outer ring
portion; and an inner disc portion, wherein the protrusion is
formed on the inner disc portion of the closure.
6. The stackable, heat processable, blow molded, plastic container
of claim 1, wherein the finish and the first closure sealingly
engage each other.
7. The stackable, heat processable, blow molded, plastic container
of claim 1, wherein the second closure is a press-fit lid.
8. The stackable, heat processable, blow molded, plastic container
of claim 1, wherein the second closure is attached to a second
container.
9. The stackable, heat processable, blow molded, plastic container
of claim 1, wherein the base of the container straddles the
protrusion of the second closure.
10. The stackable, heat processable, blow molded, plastic container
of claim 1, wherein the base further comprises: an annular standing
ring having an outer portion and an inner portion, the outer
portion merging with the substantially cylindrical sidewall; a
bottom wall defining a central concavity surrounded by the standing
ring; and an annular stacking ring interposed between the inner
portion of the annular standing ring and the bottom wall operative
to engage the portion of the protrusion of the second closure.
11. The stackable, heat processable, blow molded, plastic container
of claim 10, wherein the annular stacking ring has outer and inner
walls, the stacking ring being more elevated at the outer wall.
12. The stackable, heat processable, blow molded, plastic container
of claim 11, wherein the annular stacking ring angles downward from
the outer wall towards the inner wall.
13. The stackable, heat processable, blow molded, plastic container
of claim 12, wherein the angle from the outer wall to the inner
wall is between 1 and 15 degrees from horizontal.
14. The stackable, heat processable, blow molded plastic container
of claim 13 wherein the angle from the outer wall to the inner wall
is approximately 7 degrees from horizontal.
15. The stackable, heat processable, blow molded, plastic container
of claim 10, wherein the bottom wall of the base further comprises:
a plurality of external ribs having an external rib base disposed
upwardly into the central concavity and an external rib apex
disposed downwardly towards the stacking ring.
16. The stackable, heat processable, blow molded, plastic container
of claim 10, wherein the annular stacking ring has a shape in
radial cross-section which is one of square, rectangular,
triangular, frustoconical, semi-circular, and semi-circular.
17. The stackable, heat processable, blow molded, plastic container
of claim 16, wherein the protrusion of the second closure has a
shape in radial cross-section which is one of square, rectangular,
triangular, frustoconical, semi-circular, and semi-circular.
18. The stackable, heat processable, blow molded, plastic container
of claim 1, wherein the body comprises: a pair of flex panels for
accommodating internal changes in pressure and volume in the
container, the panels being disposed opposite one another in the
body and each panel being planar.
19. The stackable, heat processable, blow molded, plastic container
of claim 1, wherein the opening of the finish has a diameter that
is smaller than a width of the body.
20. The stackable, heat processable, blow molded, plastic container
of claim 1, further comprising ribs in the sidewall.
21. The stackable, heat processable, blow molded container of claim
1, wherein the first and second closures are identical.
22. The stackable, heat processable, blow molded, plastic container
of claim 10, wherein the annular stacking ring has a diameter that
is less than a width of the body.
23. A stack of heat processable, blow molded, plastic containers
comprising: a first container having a body having top and bottom
ends and a tubular sidewall, a dome with a finish having an
opening, the dome being connected to the top end of the body, and a
base connected to the bottom end of the body, the base having a
stacking ring; and a second container having a body having top and
bottom ends and a tubular sidewall, a dome with a finish having an
opening, the dome being connected to the top end of the body, a
closure having a protrusion and being adapted to engage the finish
of the second container, and a base connected to the bottom end of
the body, wherein the protrusion of the closure of the second
container is adapted to engage the stacking ring of the first
container.
24. The stack of heat processable, blow molded, plastic containers
of claim 23, wherein the dome of the second container creates an
indentation in the stack such that the base of the first container
only makes contact with the closure of the second container.
25. The stack of heat processable, blow molded, plastic containers
of claim 23, wherein the bodies of the first and second containers
have different widths.
26. The stack of heat processable, blow molded, plastic containers
of claim 25, wherein the openings of the first and second
containers have the same diameter.
27. The stack of heat processable, blow molded, plastic containers
of claim 25, wherein the closures of the first and second
containers have the same diameter.
28. A stackable, blow molded, plastic container comprising: a body
having top and bottom ends and a tubular sidewall; a dome with a
finish having an opening, the dome being connected to the top end
of the body, the finish adapted to engage a first closure; and a
base connected to the bottom end of the body, the base being
contoured to engage a portion of a protrusion on a second closure,
wherein one of the body, dome and base has a distortion resistant
structural element.
29. The stackable, blow molded, plastic container of claim 28,
wherein the distortion resistant structural element resists
distortion caused by one of hot-fill processing, retort processing
and pasteurization.
30. The stackable, blow molded, plastic container of claim 28 ,
wherein the base further comprises: an annular standing ring having
an outer portion and an inner portion, the outer portion merging
with the substantially cylindrical sidewall; a bottom wall defining
a central concavity surrounded by the standing ring; and an annular
stacking ring interposed between the inner portion of the annular
standing ring and the bottom wall operative to engage the portion
of the protrusion of the second closure.
31. The stackable, blow molded, plastic container of claim 30,
wherein the distortion resistant structural element resists
distortion caused by one of hot-fill processing, retort processing
and pasteurization.
32. A stack of blow molded, plastic containers comprising: a first
container having a body having top and bottom ends and a tubular
sidewall, a dome with a finish having an opening, the dome being
connected to the top end of the body, and a base connected to the
bottom end of the body, the base having a stacking ring; and a
second container having a body having top and bottom ends and a
tubular sidewall, a dome with a finish having an opening, the dome
being connected to the top end of the body, a closure having a
protrusion and being adapted to engage the finish of the second
container, and a base connected to the bottom end of the body,
wherein the protrusion of the closure of the second container is
adapted to engage the stacking ring of the first container, and one
of the dome, body and base of the first container has a distortion
resistant structural element.
33. The stackable, blow molded, plastic container of claim 30,
wherein the distortion resistant structural element of the first
container comprises means for resisting distortion caused by
hot-fill processing of the container.
34. The stackable, blow molded, plastic container of claim 30,
wherein the distortion resistant structural element of the first
container comprises means for resisting distortion caused by retort
processing of the container.
35. The stackable, blow molded, plastic container of claim 30,
wherein the distortion resistant structural element of the first
container comprises means for resisting distortion caused by
pasteurization.
36. A method of manufacturing a plastic container adapted for use
with a selected heating process comprising: providing a body having
top and bottom ends and a tubular sidewall; providing a dome with a
finish having an opening, the dome being connected to the top end
of the body, the finish adapted to engage a first closure; and
providing a base connected to the bottom end of the body, the base
having a stacking ring contoured to engage a portion of a
protrusion on a second closure.
37. The method of claim 36, wherein the selected heating process
comprises hot-fill processing.
38. The method of claim 36, wherein the selected heating process
comprises retort processing.
39. The method of claim 36, wherein the selected heating process
comprises pasteurization.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates to a container having a stackable
base and a complementary closure. More particularly, the invention
is a base for a heat processable plastic container having a
stacking ring to engage a complementary protrusion on a closure of
a second container.
[0003] 2. Description of the Related Art
[0004] Known containers include bottles, jars, tubs and pails.
Closures for such containers include screw caps and press-fit lids,
and may be one structural piece or made of a plurality of
structural component pieces, exclusive of sealing rings and/or
liners. Such closures may include a raised peripheral ring around
the top to provide improved strength. Ribbed closures are known and
have a raised peripheral ring with vertical striations on the skirt
to facilitate gripping by a user. Ribbed closures may be made as
one piece structures or structures having a plurality of pieces.
Closures may include protective liners and sealing means including
but not limited to gaskets and liners.
[0005] One piece closure structures include screw caps and
press-fit lids, and may be employed to close bottles, jars, tubs,
and pails filled with foodstuffs and other consumer products. Two
piece closure structures include screw caps and lids, and have an
outer ring and an inner portion such as a disc. The outer ring may
be threaded and generally has an upper flange in which the inner
portion is seated. Examples of two piece closure structures include
the well-known canning jar lid and vacuum sealable lids seated in
ribbed rings. Complex closure structures include caps and lids and
may additionally include valves and measuring means. An example of
a complex closure is a laundry liquid container provided with a
screw cap fitted with a press valve.
[0006] Known containers can be stacked but stability of the stacked
containers is often inadequate because resistance to being tilted
is poor.
[0007] Accordingly, it is an object of the present invention to
provide a container, which can be stacked with similar or
dissimilar containers to provide a stable stack having greater
resistance to being tilted.
[0008] It is another object of the present invention to provide a
method for improving stackability of a plurality of containers.
SUMMARY OF THE INVENTION
[0009] The above and other objects of the invention can be
accomplished by an embodiment of a stackable, heat processable,
blow molded, plastic container having a body that has top and
bottom ends and a tubular sidewall. The container also has a dome
with a finish having an opening. The dome is connected to the top
end of the body and the finish is adapted to engage a first
closure. The container has a base connected to the bottom end of
the body. The base is contoured to engage a portion of a protrusion
on a second closure.
[0010] In another embodiment, a stack of heat processable, blow
molded, plastic containers includes a first container having a body
with top and bottom ends and a tubular sidewall. The first
container has a dome with a finish having an opening. The dome of
the first container can be connected to the top end of the body.
The first container also has a base connected to the bottom end of
the body. The base is contoured to engage a portion of the
protrusion of a second closure on the second container. The stack
further includes the second container having a body having top and
bottom ends and a tubular sidewall. The second container also has a
dome connected to the top end of the body with a finish having an
opening. The second container has a closure having a protrusion and
being adapted to engage a finish of the second container, and a
base connected to the bottom end of the body. The base of the first
container has a stacking ring contoured to engage a portion of the
protrusion of the closure of the second container. To be stackable,
the stacking ring of the first container is adapted to engage the
protrusion on the closure of the second container.
[0011] In yet another embodiment, a stackable, blow molded plastic
container has a body, dome and base. One of the body, dome and base
has a distortion resistant structural element that is capable of
resisting distortion caused by subsequent hot-fill, retort, or
pasteurization processes.
[0012] Yet another embodiment provides a method for manufacturing a
plastic container adapted for use with filling processes which are
conducted at elevated temperatures such as hot-fill processing,
retort processing, pasteurization, and the like. The method
includes the steps of providing a body, dome and base of the
container. The base includes a stacking ring that is contoured to
engage a closure of a second container.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 shows an exemplary embodiment of a stackable, heat
processable, blow molded, plastic container according to the
present invention;
[0014] FIG. 2 is a perspective view of an exemplary embodiment of a
base of a plastic container according to the present invention;
[0015] FIG. 3 is a detailed view of an exemplary embodiment of a
base of a plastic container according to the present invention;
[0016] FIG. 4 is a detailed view of an exemplary embodiment of a
base of a plastic container according to the present invention;
[0017] FIG. 5 illustrates an exemplary embodiment of a stacking
arrangement according to the present invention;
[0018] FIGS. 6A, 6B, 6C, 6D, and 6E are partial cross-sectional
views showing alternative embodiments of container bottoms having
bases with the stackable contoured structure of the invention mated
with protrusions of a closure of a second container having contour
variations in which:
[0019] the base shown in FIG. 6A has an indented angled
cross-section mated with a protrusion shown as an angled
protrusion;
[0020] the base shown in FIG. 6B has an indented rectangular
cross-section mated with a protrusion shown as a rectilinear
protrusion; and
[0021] the base shown in FIG. 6C has an indented frustoconical
cross-section mated with a protrusion shown as a rectilinear
protrusion;
[0022] the base shown in FIG. 6D has an indented triangular
cross-section mated with a protrusion shown as a triangular
protrusion;
[0023] the base shown in FIG. 6E has an indented semi-circular
cross-section mated with a protrusion shown as a semi-circular
protrusion;
[0024] FIG. 7 illustrates an exemplary embodiment of a stacking
arrangement according to the present invention;
[0025] FIG. 8A shows an exemplary embodiment of a closure according
to the present invention;
[0026] FIG. 8B shows an exemplary embodiment of a closure according
to the present invention; and
[0027] FIG. 9 shows a perspective view of an exemplary embodiment
of a plastic container according to the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0028] Heat processable, blow molded containers are designed to
withstand the rigors of filling processes including without
limitation: hot-fill processing, retort processing and
pasteurization. The use of plastic, particularly blow molded
polyethylene terephthalate (PET), in the manufacture of such
containers has become commonplace and presents opportunities for
creating unique design characteristics. However, design
restrictions imposed to allow for heat-processing simultaneously
presents particular challenges for achieving useful modifications.
This is true with most of the other common materials used to make
such plastic containers, for example polyolefins.
[0029] The hot-fill process is the procedure by which containers
are filled with a beverage or some other liquid at a high
temperature and capped soon thereafter. As the beverage or liquid
cools within the container, stresses and strains develop in the
container due to changes in the volume of the contents.
[0030] In retort processing, a container is filled at ambient
temperature and capped, heated to high temperatures, for example,
260.degree. F. at super-baric pressures (i.e., up to 45 psi) and
then cooled back to ambient temperatures.
[0031] Pasteurization involves filling a container with a liquid or
other substance that has an elevated temperature, for example,
140.degree. F., and then raising the temperature to high
temperatures, such as, 220.degree. F. to 240.degree. F. and then
allowing the container and its contents to cool to ambient
temperature.
[0032] Heat processable containers are subjected to varying
internal pressures and volumetric changes (depending on the heat
process used) due to higher processing temperatures, and therefore,
expansion of the contained products and associated vapors. Without
structural support, heat processing can cause plastic containers to
distort in a commercially-unacceptable manner. Improved base
construction can prevent the base of a plastic container from
undergoing excessive outward deflection, i.e., deflection below the
container standing ring.
[0033] These improved bases typically include, at least, a standing
ring and a central concavity, known as a push-up, to prevent
distortion. The presence of a standing ring and a push-up in the
heat processable container may reduce the container's stackability
because there is not a large surface area in the base of the
container to make contact with another container. Stackability may
be further reduced if the container has an upper end or closure or
the like that also fails to provide a large surface area to mate
with the base of another container. In that situation, the surface
areas of the base and the upper portion of another container must
align for the containers to stack.
[0034] In such an arrangement, although the containers are
stackable, they are not likely to be capable of being tilted. To
improve the tiltability of such a stack of containers, the base of
the container, more particularly, the portion of the standing ring
that mates with closure of another container can be contoured so as
to straddle a closure of another container.
[0035] As used herein, the phrase straddle is intended to include
essentially any straddling engagement, i.e., surface area
engagement, since an engagement of even about 1% of the protrusion
by the base is somewhat effective to improve stackability of such
containers. In exemplary embodiments, the engagement is greater
than about 50% of the protrusion and can be near 100%.
[0036] For example, in embodiments where a first container is a
tubular jar and is stacked in mating engagement on a protrusion of
round screw cap of a second container, the percent of straddling
engagement, i.e., surface area engagement, would be determined as
follows. In this example, the base of the tubular jar has the
contour of an indented annular ring in a bottom view having inner
and outer diameters and having the radial cross-section of a
rectangle of 2 mm by 4 mm which is open on one of the 4 mm sides so
as to straddle the peripheral rim of the screw cap. In this
example, the protrusion of the screw cap has inner and outer
diameters which are approximately equivalent to those of the
indented annular ring contour of the base, has about a 4 mm
difference between its outer and inner diameters, and is raised
about 2 mm from a central flat portion of the screw cap. Thus, the
percent of straddling engagement, i.e., surface area engagement, of
the indented annular ring of such a base on such a protrusion would
be approximately 100%, that is, a substantial mating engagement. In
other exemplary embodiments, the indented annular ring in the
container base and protrusion on the closure may have dimensions of
about 2 mm.times.6 mm. Variations from substantial mating
engagement may be due to (a) differences in the radial
cross-sectional shapes of the base and the peripheral rim, (b)
differences in respective diameters, (c) differences in the
completeness with which the base covers the periphery of the
protrusion; and (d) varying tolerances during the manufacturing
process.
[0037] Referring now to the figures, FIG. 1 shows an exemplary
embodiment of a stackable, heat processable, blow molded container
10 that can include a base 16 (and complementary closure) for
improving the stackability and tiltability of a stack of
containers. Container 10 can have a body 11 formed by sidewall 12.
Body 11 can have a width W measured by the width of sidewall 12 at
its widest point. Sidewall 12 can be tubular. As referred to
herein, tubular means non-tapered and can include cross sections
which may be substantially cylindrical, square, or other shapes.
For example, as shown in FIG. 1, sidewall 12 is substantially
cylindrical. As shown in FIG. 9, sidewall 12 can be substantially
square. This and other exemplary embodiments can be shown in
further detail in U.S. patent application Ser. No. 10/366,617,
which is incorporated herein by reference in its entirety and is
owned by the assignee of the present invention.
[0038] Sidewall 12 can include a pair of flex panels 73a and 73b
(as shown in FIG. 7) that can be opposite one another in body 11
and each flex panel 73a and 73b can be planar. Sidewall 12 can also
include a plurality of sidewall ribs 74 (as shown in FIG. 7).
Sidewall ribs 74 can be horizontal or vertical (not shown).
Particular embodiments of body 11 that include flex panels 73a, 73b
and sidewall ribs 74 are shown in U.S. Pat. No. 6,439,413, which is
incorporated herein by reference in its entirety and is owned by
the assignee of the present invention.
[0039] Container 10 can also have a dome 13 that can merge with
sidewall 12. Dome 13 can have a finish 14 that can define an
opening 15 for filling and pouring the contents of container 10.
Dome 13 can be a conventional dome, meaning dome 13 narrows
sidewall 12 to finish 14. Finish 14 can be adapted to receive
closure 50 (shown in FIG. 5) as discussed in detail below.
[0040] Container 10 can also have a base 16 that can be contoured
so as to straddle closure 50 of another container as shown in FIGS.
5 and 7. As shown in FIG. 2, base 16 can have standing ring 20 for
contact with a horizontal surface (not shown) on which the
container can rest. Base 16 can also have bottom wall 26 that
defines a central concavity 26a known as a push-up. Stacking ring
23 can be interposed between standing ring 20 and bottom wall 26.
Stacking ring 23 can be a continuous ring, but in another exemplary
embodiment, stacking ring 23 need not be complete and may have
gaps. In yet another embodiment, stacking ring 23 can have an
incomplete radial cross-section because stacking ring 23 can adjoin
flat portion 28 of labeling lug 29. As shown in FIG. 3, stacking
ring 23 can have a diameter D.sub.2 that extends across stacking
ring 23 on center. In an exemplary embodiment, sidewall width W
greater than stacking ring diameter D.sub.2.
[0041] Standing ring 20 can have outer portion 21 that can merge
base 16 with sidewall 12. Standing ring 20 can also have inner
portion 22 that can merge with outer wall 24 of stacking ring 23.
Stacking ring 23 can include inner wall 25 that can merge with
bottom wall 26. In an exemplary embodiment, at least a portion of
outer wall 24 and inner wall 25 can be vertical, i.e.,
substantially parallel to sidewall 12. Push-up 26a can have a
plurality of support ribs 27 extending radically from the central
concavity. Support ribs 27 can have a base disposed upwardly into
the central concavity and an apex disposed downwardly towards
stacking ring 23.
[0042] As shown in FIG. 3, support ribs 27 can have a trapezoidal
shape. In an alternative support ribs 27 can have a pyramidal
shape. In yet an alternative exemplary embodiment, push-up 26a does
not include support ribs 27. This and other exemplary embodiments
of base 16 are shown in U.S. patent application Ser. No.
10/366,574, which is incorporated herein by reference in its
entirety and is owned by the assignee of the present invention.
[0043] FIG. 4 shows a detailed cross-section of stacking ring 23.
In an exemplary embodiment, stacking ring 23 can be angled downward
at an angle .alpha. from outer wall 25 to inner wall 24. Angle
.alpha. can be between 1.degree. and 15.degree. from horizontal.
More particularly, angle .alpha. can be approximately 7.degree.
from horizontal.
[0044] As shown in FIG. 5, stacking ring 23 can mate with
protrusion 51 of closure 50 to provide the desired stackability and
tiltability. Closure 50 can mate with stacking ring 23 by aligning
protrusion 51 with stacking ring 23. In such a mating engagement,
the stacking ring 23 of container 10 can straddle the protrusion 51
of closure 50. Specifically, standing ring 20 can surround
peripheral wall 52 of closure 50. Closure 50 can have a diameter
D.sub.3 that is measured across the center of protrusion 51. In an
exemplary embodiment, closure diameter D.sub.3 is approximately
equal to stacking ring diameter D.sub.2.
[0045] In an exemplary embodiment, closure 50 can be one contiguous
piece (as shown in FIG. 5), such as a press-fit or screw-on lid or
the like, and protrusion 51 can form a peripheral ring around
closure 50. In another exemplary embodiment, as shown in FIG. 8B,
closure 50 can be a two-part closure. Closure 50 can have inner
disc portion 82 and a ring 81. In this embodiment, protrusion 51
can be formed on ring 81. In another embodiment, as shown in FIG.
8A, protrusion 51 can be formed on inner disc portion 82. In either
embodiment, ring 81 can have a substantially vertical skirt 84 with
internal threads (not shown) to threadedly engage a finish of
another container. Skirt 84 can have external vertical striations
83 to aid gripping.
[0046] FIGS. 6A, 6B, 6C, 6D and 6E are partial cross-sectional
views showing alternative embodiments of container 10 having bases
16 with the stackable contoured structure of the invention mated
with protrusions 51 of closure 50 having contour variations.
Stacking ring 23 of base 16 shown in FIG. 6A has an intended angled
cross-section mated with protrusion 51 shown as an angled
protrusion. Stacking ring 23 of base 16 shown in FIG. 6B has an
intended rectangular cross-section mated with protrusion 51 shown
as a rectangular protrusion. Stacking ring 23 of base 16 shown in
FIG. 6C has an indented frustoconical cross-section mated with
protrusion 51 shown as a rectilinear protrusion. Stacking ring 23
of base 16 shown in FIG. 6D has an indented triangular
cross-section mated with a protrusion 51 shown as a triangular
protrusion. Stacking ring 23 of base 16 shown in FIG. 6E has an
indented semi-circular cross-section mated with protrusion 51 shown
as a semi-circular protrusion. As will be appreciated by persons
skilled in the art, the configurations illustrated in FIGS. 6A-6E
are non-limiting and other configurations can be used. Further, it
will be appreciated that the objects of the invention can be
achieved without the stacking ring 23 and protrusion 51 having
identical shapes. For example, the rectangular protrusion 51 (FIG.
6B) can mate with an angled stacking ring 23 (FIG. 6A).
[0047] FIG. 7 shows an exemplary embodiment of a stack 70 of
containers 71, 72 according to the present invention. Stack 70 can
include top container 71 and bottom container 72. Top container 71
can include base 16 that is contoured, thus forming a stacking ring
as described in FIGS. 2-6, to straddle a protrusion on closure 50
of bottom container 72, as described in any of FIGS. 5, 6 and 8. In
the mating arrangement shown in FIG. 7, sidewall width W is greater
than stacking ring diameter D.sub.2 and stacking ring diameter
D.sub.2 is equal to closure diameter D.sub.3, thus causing the top
container to straddle the bottom container. This straddling has the
effect of improving stackability and tiltability.
EXAMPLE
[0048] The significantly improved resistance to tilting of a stack
of containers according to the present invention was demonstrated
in the following tests conducted on containers, which were bottles
fitted with two piece screw caps. The containers were equivalent
except that the "control containers" did not have a base according
to the present invention defined in their bottoms. The "stackable
containers" according to the invention had bases as illustrated in
FIGS. 2-5 and 6A.
[0049] A two-piece 63 mm ribbed closure was employed which included
a plastic ring having a peripheral rim with a raised annular
section with a 65.9 mm outer diameter and a 54 mm inner diameter,
and a metal disk positioned within and retained by the ring. The
raised annular section had a radial cross-sectional shape, which
was generally rectangular and extended vertically above the plane
of the metal disk by about 2 mm. The width of the longer leg of the
rectangle was about 6 mm. Containers according to the invention
which were provided with a base had a complementary radial
cross-sectional shape and not only engaged and straddled the
peripheral rim of the container below it in a stack but featured a
mating engagement because of the complimentary shapes, dimensions,
and diameters.
[0050] A plastic jar weighing 50 grams.+-.1 gram and having an
overflow volume of 705 cc.+-.20 cc was modified to have a stackable
base according to the invention, i.e., "stackable container".
Unmodified jars provided the "control containers". Water weighing
686 grams at ambient temperature was filled into both types of
containers.
[0051] The empty and water-filled containers were stacked 2, 3, or
4 high on a horizontal surface and each stack's resistance to being
tilted was tested by tilting the surface in a controlled manner.
Table 1, which follows gives the degree from vertical, tolerated by
each stack before the top container fell from the stack. As a
practical matter, the falling of one container was generally
accompanied by toppling of the entire stack.
1TABLE 1 Comparison of Degrees from Vertical Tolerated by the Stack
Indicated Control Containers: Stackable Containers: Number/Stack
Empty Filled Empty Filled 2 15 20 30 35 3 12 15 25 28 4 9 10 17
22
[0052] As can be readily seen from the data of Table 1, a stack of
"stackable containers" according to the invention had a
significantly a greater resistance to toppling when tilted than a
stack of "control containers" whether empty of filled with water.
Such improved stackability is clearly advantageous to retailers in
general and grocers in particular.
[0053] It is understood that various other modifications will be
apparent to and can be readily made by those skilled in the art
without departing from the scope and spirit of the present
invention. Accordingly, it is not intended that the scope of the
claims appended hereto be limited to the description set forth
above but rather that the claims be construed as encompassing all
of the features of patentable novelty which reside in the present
invention, including all features which would be treated as
equivalents thereof by those skilled in the art to which the
invention pertains.
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