Note: Descriptions are shown in the official language in which they were submitted.
CA 02555513 2003-02-26
PLASTIC CONTAINER
This application is a division of commonly owned Canadian Patent Application
Serial
Number 2,420,434 filed February 23, 2003.
DESCRIPTION
FIELD OF THE INVENTION
[0001] The present invention is directed to plastic containers. More
specifically, the
present invention relates to blow molded shaped plastic containers,
particularly beverage
containers. A first aspect of the present invention, as defined in the parent
application, is
directed to the panel design for hot fillable plastic containers, such as
those for hot fill beverages.
More specifically, this first aspect of the present invention is directed to a
panel design for hot
finable plastic containers having flat vacuum side panels. A second aspect of
the present
invention, as defined herein, is directed to mufti-Iayer plastic containers.
More specifically, this
aspect of the present invention is directed to plastic containers having a
seven layer polymer
structure. A third aspect of the present invention is directed to plastic
containers having the
panel design of the first aspect and the seven layer structure of the second
aspect of the present
invention.
BACKGROUND OF THE INVENTION
[0002] Hot filled containers are designed for packaging of liquids which must
be placed
in the container while hot to provide for adequate sterilization. During
filling, the container is
subjected to elevated temperatures of approximately 180° to 185°
F. (the product temperature)
and positive internal pressures of approximately 2 to 5 psi (the filling line
pressure). The
container is then capped, and as the product cools, a negative internal
pressure is formed in the
sealed container. The hot fill, however, can cause distortion and shrinkage of
the container. It is
desired that the volumetric shrinkage be limited to no greater than 1 %.
[0003] Many different types of containers have been created to receive a hot-
fill product
and meet the objectives of a minimum amount of thermal shrinkage and
distortion. However,
prior efforts to produce bottles for handling hot filling and to meet the
above objections have
necessarily included panels having indents, detents, protruding surfaces
and/or recessed surfaces
functioning as so-called vacuum panels for container stress relief.
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[0004] For example, U.S. Patent No. 4,863,046 (Collette et al.) discloses a
blow molded
container for receiving a hot fill product. The container in the '046 patent,
however, does not
have flat side panels but instead has a series of indents or recessed portions
and ribs in the side
panels in order to minimize shrinkage and increase longitudinal stiffness of
the panel section.
[0005] Another patent disclosing a plastic container with vacuum panels is
U.S. Patent
No. 5,704,503 (Krishnakumar). The container in the '503 patent also does not
have flat vacuum
panels, but instead requires longitude post ribs flanked by walls, in between
recessed vacuum
panels. Hoop ribs are also provided around the panel.
[0006] U.S. Patent No. 4,877,141 (Hayashi et al.) shows another type of vacuum
panels.
The '141 patent also does not have flat panels, but rather the panels have
stress absorbing strips
to prevent deformation of the container. Each panel is also surrounded by
outer sheaths.
[0007] Accordingly, these prior containers taught the need to have specially
designed
structures to accommodate volume changes upon cooling of hot filled products.
These
containers did not have flat vacuum panels.
[008] Therefore, one object of an embodiment of the present invention is to
provide a
flat vacuum panel structure, without the need for any such ribs or stress
absorbing strips. This
provides smooth sides for ease of label application and cleanness of
appearance, while still
maintaining a sufficient top load rating. The smooth sides also provide an
appealing feel for the
consumer, especially in the label area which does not suffer from the wrinkled
feel of labels on
prior containers.
[0009] Another aspect of plastic containers relates to the plastic polymer
used to mold
the container. Frequently, a multilayer polymer composition is used to provide
strength and
other benefits to the container.
[0010] For example, U.S. Patent No. 4,182,457 (Yamada) discloses a multi-layer
container and several embodiments thereof, including some with seven layers.
Some are
mentioned at columns 9 and 28 therein. These structures, however, have a
polyolefin as the
innermost layer. Polyolefins have been found to rapidly strip the limonene out
of fruit or citrus
juices. This adversely affects the taste of the juice as limonene and other
important flavor and
color components contribute to desirable tangy flavors and color of the
juices.
[0011] U.S. Patent No. 4,990,382 (Weissenstein et al.) discloses laminated
blow molded
containers which are said to provide a glass like appearance. The '382 patent
also discloses
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some containers with seven layer structures. In these containers, the interior
layer is a
polypropylene followed by a layer of adhesive, a barrier layer, another layer
of adhesive, a
relatively thick layer formed of regrind scrap containers, a third layer of
adhesive and an outside
gloss coat layer formed from plastic materials including ethylenelvinyl
alcohol copolymer
(EVOH) and nylon and mixtures thereof. Since this container has polypropylene,
a polyolefin,
as the inner most layer, the container will quickly strip the limonene and
other important flavor
and color components out of fruit juice therein and adversely affect the taste
and color of the
juice.
[0012] Reissue Patent No. Re 34,546 (Deyrup) is directed to the use of high
density
linear polyethylene for containers and also generally discloses the use of
seven layer structures
for containers. Deyrup '546 recites for example a seven layer structure
including polyethylene,
adhesive, EVOH, adhesive, polyethylene, adhesive and polyamides or nylons.
While an
amorphous polycarboxlamide is used as an inner layer in some of the structures
of this patent,
neither a layer of polypropylene nor a layer of regrind is used.
[0013] Therefore, an object of the present invention is to provide a plastic
container
having a specific seven layer structure which is suitable for storage of
beverages of juices, dairy
products and combinations thereof and which will not adversely affect the
taste and color of the
beverages therein.
[0014] Still another object of the present invention is to provide a plastic
container
having a flat vacuum panel structure and a specific seven layer structure
which is suitable for
storage of beverages of juices, dairy products and combinations thereof.
SUMMARY OF THE INVENTION
[0015] The present invention is directed to plastic containers including those
formed by
blow molding, which are especially suitable for long-term storage of beverages
that are hot filled
into the containers.
[0016] In accordance with the parent application, the container has a
rectangular cross-
section body portion with four panels wherein each of the four panels is
relatively flat, but
flexible. These panels function as vacuum panels which buckle slightly
inwardly in response to
cooling of the hot filled liquid. The panels can move from a planar
configuration and a bowed
configuration in response to filling with hot product and cooling after
filling. By having virtually
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flat panels, label application to the container is simplified while providing
a smooth, aesthetically
pleasing look and feel.
[0017] In accordance with the present invention, the container has walls
formed of a
polymeric material having a seven layer structure of polypropylene, adhesive,
EVOH, adhesive,
regrind, adhesive, and amorphous nylon. Preferably, the polypropylene forms
the outside of the
container wall while the amorphous nylon forms the innermost layer which
contacts the contents
of the container. The amorphous nylon layer prevents the beverages from losing
their color and
taste, due to either scalping of key favor and color components out of the
juice and into the
plastic and/or imparting from the plastic off note plastic flavors into the
juice. The other layers
provide strength and a barrier layer for contaminants.
[0018] In another embodiment of the present invention, the container has the
flat panel
walls of the parent application and is formed as a polymeric material having
the seven layer
structure of the present application.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 is a perspective view of a beverage container of a first
embodiment of the
present invention.
[0020] FIG. 2 is an elevational view of the container of FIG. 1.
[0021] FIG. 3 is a top plan view of the container of FIG. 1.
[0022] FIG. 4 is a bottom plan view of the container of FIG. 1.
[0023] FIG. 5 is a perspective view of another example of a container of the
first
embodiment of the present invention.
[0024] FIG. 6 is an elevational view of the container of FIG. 5.
[0025] FIG. 7 is a cross-sectional view of the seven layers of the polymeric
material of a
container of a second embodiment of the present invention.
DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS
[0026] FIGS. 1-4 show a first embodiment of the present invention. This
embodiment is
directed to a plastic container 10, preferably a beverage bottle, for hot fill
liquids. The bottle
includes an open mouth 12 to receive hot finable liquids, a bell (or upper)
area or portion 13, and
a body (or lower) area or portion 15.
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[0027] Concerning the bell area 13, surrounding the mouth 12 is a neck 14 to
receive a
cap [not shown]. Preferably, the neck 14 has threads for screwing on the cap.
Below the neck is
a shoulder section 16 which increases generally in width from the neck to a
maximum point,
lower on the container. The width then decreases to a recessed area 18. Then,
below the
recessed area 18 is a first elevated ridge 20. This bell area helps to provide
an acceptable top
load rating for the container. The top load rating relates to the ability of
the container to have
other items, particularly other containers, stacked thereon. In this
embodiment, a top load rating
of at least 80 pounds has been achieved. The bell area 13 is able to provide
sufficient strength so
that it is not necessary for the body portion 15 to provide a means for
supporting a top load
weight which could include indents, detents, protruding surfaces and/or
recessed surfaces.
[0028] The body portion 15 is generally defined as follows. The body portion
15
includes below the first elevated ridge 20 a rectangular (longitudinally)
lower body portion or
panel section 22. Below the panel section 22 is a second elevated ridge 24 and
a base 26. As
shown, the elevated ridges 20 and 24 have a greater width (in transverse
bottle cross section)
than the panel section 22. Ridges 20 and 24 act to isolate the panel section
and allow the panel
section to act as vacuum panels. These ridges also act as bumpers for the
bottles to keep the
bottles flush to one another on a conveyor belt during filling and/or capping
and to keep them
moving along the conveyor belt. The ridges could also operate as protection
for a label located
only on the side panels. Base 26 preferably includes a recessed closed bottom
28 as shown in
FIG. 4 which moves inwardly to cooperate with the panel section 22 in order to
reduce the
negative pressure during product cooling.
[0029] Preferably, the panel section 22 has a transverse cross-sectional shape
which is
square but is not limited to this shape. More preferably, the panel section
has four flat side
panels which are rectangular. Typically, the side panels are substantially
identical in size, shape,
thickness and composition. In a further embodiment, the mold line (not shown)
for the container
is located on two opposing side panels, as opposed to in the corners. In this
embodiment, these
opposing side panels may be slightly thicker than the other side panels.
[4030] Each side panel 30 is not only flat but flexible and has no ribs,
stress absorbing
strips, recessed areas, or other similar obstructions to panel bowing. Each of
the side panels
preferably has smooth corners 34 between the two panels. A label can then be
smoothly and
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easily applied to the bottle. For example, a label 36 could extend from the
top shoulder 16 to
base 26. The present invention, however, is not limited to the size or length
of the label.
[0031] While FIGS. 1-4 show the side panels having a long longitudinal length,
the
panels can be of any length as for example shown in FIGS. 5-6. In these
figures, side panel 38
has a much shorter height. Otherwise, the plastic container of FIGS. 5-6 is
essentially the same
as the container shown in FIGS. 1-4.
[0032] The second embodiment of the present invention is directed to a plastic
container
formed of a polymeric material and having a seven layer structure. FIG. 7 is a
cross-sectional
view of the seven layers in the plastic polymeric material of the walls of the
container. In this
embodiment, the plastic polymeric material has four structural layers and
three adhesive layers.
[0033] As shown in FIG. 7, the exterior surface 102 of the container of this
embodiment
is made of polypropylene, such as a virgin polypropylene. The mid-outer layer
104 is an
adhesive. The mid-interior layer 106 is ethylene-vinyl alcohol polymer (EVOH).
The next layer
108 is another layer of adhesive. 'The next layer 110 is a re-grind layer. It
is an interior,
sandwiched layer. This is a "scrap" of the seven layer co-extrusion which has
been collected and
ground into polymer. Preferably the bulk of the co-extrusion is the re-grind
material, making up
to approximately 70 percent of the total thickness of the extrusion. The next
layer is another
adhesive layer 112. These layers act as a barrier to keep contaminants from
the beverage and to
give strength to the container. As a result, the beverage within the container
will have a longer
shelf life than other containers with such a combination of layers. The
contact or innermost layer
114 is a polyamide, such as an amorphous nylon. It is the amorphous nylon
layer which contacts
the contents of the container, such as a beverage within the container. The
nylon layer does not
strip the limonene and other important flavor and color components out of the
beverage. As a
result, a fruit or citrus containing beverage will maintain its tangy flavor
and color longer and
will not have a plastic taste.
[0034] 'The following is an example of a plastic container having a seven
layer
construction in accordance with this embodiment of the present invention.
Preferably, for a 12-
ounce container such as shown in FIG. 1, the weight of the bare bottle is 27
grams. Materials
used included a polypropylene (Marlex~) manufactured by Phillips, manufacturer
No. RGN-020;
an EVOH (Soarnol~) from Soarus, manufacturer No. DCF3203F; and a nylon from
Dupont
(Selar~), manufacturer No. PA3426. An adhesive from Dupont (Bynel~),
manufacturer No.
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CXA SOE571, was used for each of the adhesive layers. These materials were
used in a
polymeric composition having the composition shown in Table 1 to produce a
plastic beverage
container in accordance with the present invention.
TABLE 1
Lad r Material Target Thickness(in)% of thickness
Outer Virgin Polypropylene 0.006 20
Mid-outer Adhesive 0.0004 1.3
Mid-inner EVOH 0.0006 (minimum) 2
Mid-inner Adhesive 0.0004 1.3
1
Inner Regrind 0.0216 72
Lower-inner Adhesive 0.0004 1.3
Contact Amorphous Nylon 0.0006 (minimum) 2
[0035] When being used to manufacture a container, typically the polymeric
material of
this embodiment initially is in the form of a parison which is extruded into a
preform and blow
molded into the desired shape. It is contemplated that this will be done in a
conventional manner
which is well known to those skilled in the art. The present invention is not
limited to a method
of extrusion or blow molding.
[0036] In a third embodiment of the present invention, a beverage container of
the first
embodiment, such as that shown in FIGS. 1-6 and described above, is formed of
a polymeric
material having a seven layer structure of the second embodiment, such as that
shown in FIG. 7
and described above. This combination is especially suitable for hot filled
beverages,
particularly those which are susceptible to development of off flavors when
stored for long time
periods such as for about six months or more in polymeric containers. The
combination is also
useful for containers for beverages containing 10 weight percent or more of
fruit or citrus juice.
Further, the combination is useful for beverages containing fruit or citrus
juice and dairy
products, such as for example a smoothie beverage with yogurt and fruit juice.
In a preferred
embodiment, the smoothie beverage includes yogurt, approximately 50 weight
percent of fruit
juice and other additives.
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[0037] It will be understood that the embodiments of the present invention
which have
been described are illustrative of some of the applications of the principles
of the present
invention. Numerous modifications may be made by those skilled in the art
without departing
from the true spirit and scope of the invention.
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